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On the seventh anniversary of her mother’s passing, Billie Lourd, the talented actress widely known for her role in “Scream Queens,” took to Instagram to pay a touching tribute to her late mother, Carrie Fisher. In a heartwarming post, Lourd shared a sweet childhood snapshot of herself and her mom, accompanied by a heartfelt caption expressing her ongoing grief and the profound impact her mother had on her life.
A Yearning for Connection
Lourd began her caption by acknowledging the passing of seven years since her mother’s death, humorously adding, “but who’s counting? Me, I guess?” She candidly revealed that each anniversary brings a different manifestation of her grief, evoking a range of emotions such as rage, sorrow, emptiness, guilt, and everything in between. This year, however, she woke up feeling grateful and coined the term “griefull” to describe this unique blend of grief and gratitude.
The Power of Grief
Grief has transformed Lourd’s perspective on life, infusing it with a newfound sense of appreciation. She finds herself savoring every moment of joy as if it were her last, cherishing the experiences she shares with her two children, Kingston and Jackson, whom she shares with her husband Austen Rydell. Lourd recounted a touching moment when she held her napping daughter and tears of joy welled up in her eyes. In that moment, she felt her mother’s presence, akin to the warmth of the sun on a summer day.
A Sparkle of Griefull
Lourd expressed that while she misses her mother every day, she also feels her constant presence. She believes that her mother lives among the stars, illuminating her life with sparkle. In her tribute, Lourd extended her love and support to all those grieving and hoped that amidst the complex emotions grief brings, everyone could find a little sparkle of “griefull.”
Remembering Carrie Fisher
Carrie Fisher, renowned for her iconic portrayal of Princess Leia in the Star Wars franchise, tragically passed away in 2016 following a medical emergency on a flight from London to Los Angeles. After being rushed to the Ronald Reagan UCLA Medical Center, Fisher was placed on a ventilator but succumbed to her condition four days later at the age of 60. The devastating loss of Fisher was compounded by the passing of her mother, Debbie Reynolds, just one day later.
Messages of Support
Lourd’s heartfelt tribute to her mother resonated with her fans and fellow celebrities. Actress Lily Collins, daughter of Genesis drummer Phil Collins, responded, “So beautifully said and felt.” Frances Bean Cobain, daughter of Kurt Cobain and Courtney Love, remarked, “moving with our grief is the most life-affirming thing we can do because it is the event that makes life so damn precious.” The outpouring of love and support from fans on this difficult anniversary was palpable.
Since her mother’s passing, Lourd has made it a tradition to post touching tributes to her “momby” on each anniversary. These tributes serve as a way for Lourd to honor her mother’s extraordinary life and enduring legacy. In May, Lourd accepted a posthumous star on the Hollywood Walk of Fame in Fisher’s name, praising Princess Leia as a symbol of strength, grace, wit, and femininity. Lourd expressed her gratitude for the character that her mother brought to life and how it has become a cherished family heirloom.
Passing the Torch
Lourd also shared how she has developed a deep love for Leia and the Star Wars universe since her mother’s passing. From initially being reluctant to watch the films, she has become an “obsessive Star Wars fan.” Lourd has passed down her love for Princess Leia to her children, Kingston and Jackson. Although they won’t have the chance to meet their grandmother, Lourd takes solace in the fact that they will know a piece of her through the iconic character. Leia has become a symbol of hope and inspiration, not just for Lourd’s family, but for countless fans who continue to be touched by her mother’s portrayal.
A Lasting Legacy
Lourd expressed her appreciation for the enduring love fans have for Princess Leia, knowing that it will continue to be passed on from generation to generation. She shared her experience at Star Wars Celebration, where she witnessed mothers, daughters, and even grandmothers dressed up as Leia, paying homage to her mother’s impact. Lourd recognizes that her mother’s legacy lives on, inspiring and resonating with people of all ages.
Billie Lourd’s heartfelt tribute to her late mother, Carrie Fisher, on the seventh anniversary of her passing, serves as a powerful reminder of the enduring bond between a mother and daughter. Lourd’s ability to find gratitude within her grief and share her experiences with her own children is a testament to the impact Fisher had on her life. As fans and loved ones continue to honor Fisher’s memory, her legacy as Princess Leia remains a symbol of strength, inspiration, and resilience for generations to come.


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domain: hobby


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Whenever I think of a young woman’s journey to an uncertain destiny, I usually think of David Palme’s Emergence – especially if the girl is under 15, has the power to take a life and is a master of disguise, diplomacy and martial arts.
Patience is the seventh seventh seventh daughter of the space captain who first came to Imaculata (we are looking here at 249th generation, 7000 years of genetic material). She’s the daughter of the rightful heir to the kingdom, the Heptarch. But she and her father serve the current ruler as diplomats. And slaves.
“Your first responsibility is the greatest good for all the world. Only when that is secure can you care for private loves and comforts and power. The King’s House is all the world.”
Her entire life, her father has protected her from her destiny. But, when he dies and his head is harvested to serve the king, she’s must run for her life, and face a destiny that has been prophesied for generations. A destiny that that will save the world – or destroy it.
She was destined to mate with Unwyrm. When Heffiji was asked who or what Unwyrm was, he replied:
“It was a large wormlike animal with vestigial wings that fanned out just like geblings’ fingers, with a head as proportionately tiny as the head of a dwelf, and with a body as long and lithe as a gaunt. Its belly looked loose and open, as if loose sections of bowel were protruding.
When Heffiji at last quieted down, Angel spoke softly from his place by the fire. “Wyrms,” he said. “The earliest colonists called them that, and killed them all, even though there was evidence that they lived communally and buried their dead. They were too frightening, they awakened too many human fears. And now they’re extinct.”
“Except one,” said Patience. “That’s what Unwyrm is, isn’t he? The last of the wyrms.”
“Not quite,” said Ruin, who looked exhausted and defeated. “We geblings named him, didn’t we? Unwyrm.
Not-wyrm. Not our father; our brother. We didn’t remember that he looked like this, didn’t remember what a wyrm was. But now it’s clear enough. Just like the second-generation gnat that killed off the other gnats and waited to mate again with the Earth wheat. That’s what Unwyrm is doing. Waiting to mate again with a human being.”
On her journey she is accompanied by Angel, her tutor, a fat boat owner, two Giblins (who are the true kings of the Giblin race), River – a head in a jar who helps navigate the treacherous waters and his monkey and eagle. And Will, a Revolutionary and one of the Giblin’s slave.
I highly recommend this book. The story is compelling and well paced, the characters complex, and the world believable.
Humans have lived on Imakulata for millenia, originating there as a Greek Orthodox religious colony. They are the ascendant race of this incredible world, maintaining an uneasy distance from the aboriginal geblings, taking the empathic gaunts as whores and catamites, enslaving the small-headed and small-brained dwelfs. Since the time of the first colonists, the Heptarchs have ruled in a seldom-broken line of descent. The Starship Captain’s prophecy holds that the seventh seventh seventh daughter of the first Heptarch will become the mother of Kristos, to either be the savior or the destroyer of humanity on Imakulata. Patience is that prophesied daughter, the only living child of the rightful Heptarch, Lord Peace. But Peace belongs to a second-generation usurper. He serves as a diplomatic slave to the man in the Heptarch’s seat. Peace teaches his daughter that the Heptarch’s House is the whole world, and that deposing the sitting Heptarch would only bring about bloody civil war. So Patience learns the arts of diplomacy from her father and from his slave Angel, the last of the Wise. Angel is the only Wise to have returned from Cranning, to where all the Wise had followed an undeniable call years ago, to restore to Lord Peace the ability to father a daughter. Together, Angel and Peace teach Patience how to perfectly mask her emotions, how to speak every language spoken on Imakulata, how to kill with the skills of an assassin, how to be impeccably loyal to the ruling Heptarch.
But the Heptarch cannot trust Peace and Patience because of what the Starship Captain’s prophecy has foretold for their destinies. He holds father and daughter effectively hostage by never letting both leave the Heptarch’s House at once, and perpetually monitors their behavior and words. Thus Patience grows up never having had a single unguarded moment with her father, and Peace’s slave becomes more her father than Peace himself. When the aging Lord Peace dies, Patience flees the Heptarch and the certain death he intends for her. She rejoins Angel, and in the company of a religious Vigilant, a pair of Geblings and a coarse river woman, they journey toward Cranning, from where the Unwyrm calls to her, seeking life for his race and death for humanity. Aided by a dwelf whose home is the storehouse for all the knowledge of the Wise and by a pair of empathic gaunts, Patience travels toward the fulfillment of her destiny — to either bear the ancient Unwyrm’s children or to slay him in his lair.
I loved the Geblings, they are such social creatures, always touching, communicating, calling each other when a task needs to be done.
She remembered so clearly how it felt, when she was each of the first few gebling kings. Yet now she felt nothing. It was like reaching out with her hand, only to discover that her hand had been cut off. She watched them wistfully, grieving that she could never know them except in the vicarious memories that came to her through the scepter. And the geblings went about their business, not knowing who she was, not guessing that she was the one living human who knew what it was like to be a gebling, who could understand the constant fellowship that gave them their anchor in the world. How did I find the courage to live before, when I never knew what it was to know another person?
And they despise humans for their aloofness, their solitude, until they get to know what technologies the humans have designed:
“But now, well, he keeps telling me that solitude is the foundation of true wisdom, that all the brilliant thoughts in this house come as the desperate cry of one human being to another, saying, Know me, live with me in the world of my mind.”
It’s a tale about invaders from space (the humans) and the way they handled the local intelligent indigenous species. Through the stone implanted in her brain, Patience has access to all her ancestor’s memories, all the way to the Starship captain who mated with a local worm (who called him, seduced him) and gave birth to Unwyrm and the first Geblings.
“If human beings are all monsters, why should I sacrifice anything for them?”
“Because they are beautiful monsters…, And when they live in a network of peace and hope, when they trust the world and their deepest hungers are fulfilled, then within that system, that delicate web, there is joy. That is what we live for, to bind the monsters together, to murder their fear and give birth to their beauty.”
The captain managed to pass a warning when giving the prophecy. His right hand wrote that the daughter 249 generations down the line will be the life mate of the Unwyrm but with his left hand he wrote: “save my daughter”.
Card’s Imakulata is a complex world in both the biological and social senses. This novel could have been twice its actual length if Card had taken the detail to a higher level. The style Card chose, though, gives Wyrms the feeling of myth, of a legend common to all of humanity’s subconscious. The self, the soul, the question of right and wrong differing from good and bad, are just some of the perplexing problems that Card sparks the philosopher in all of us to think about. Card seamlessly interweaves adventure with the most unsolvable problems of the mind. Wyrms carries special appeal to those who are fans of the Ender books, but could serve equally well as an introduction to Card’s work for any reader seeking thought-provoking, solid speculative fiction.

domain: literature


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Designer: Juneau Luxe
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Limited inventory available. Free shipping on orders over $100!

domain: design


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Operated by ?
A tapestry takes different threads and colors, and weaves them together into a beautiful design. That’s what this Italy tour—Italian Tapestry—does. It weaves together Italy’s most famous cities, its must-see attractions, and its marvelous scenery to create a wonderful vacation. Overnight on Venice Island, and in Florence, Siena, Rome, and Sorrento. Visit each city’s well-known landmarks and attractions, such as St. Mark’s Square in Venice; the Academy of Fine Arts with Michelangelo’s David in Florence; the Piazza del Campo in Siena, where the Palio medieval-style horse race is held; and St. Peter’s Basilica, the Sistine Chapel, and the Colosseum in Rome, where you can imagine what it was like to partake in the deadly gladiatorial fights. Plus, Globus has worked hard behind the scenes to get you front and center at many of these sights with special VIP access.
Other highlights of this Italy tour include a jetfoil ride from Sorrento to the world-famous Isle of Capri, where you’ll ride the funicular to the village for a guided tour and a visit to Augustus Gardens. . In Pompeii, a guided walking tour introduces you to the excavations of the city both destroyed and preserved by an eruption of Mount Vesuvius in 79 AD—an amazingly detailed look into life around 2,000 years ago at the peak of the Roman Empire.
All of this—plus a gondola serenade in Venice, a balsamic vinegar tasting near Modena, and a farewell dinner with a taste of Limoncello at a Sorrento restaurant—come together perfectly to create an Italy vacation like no other.
Please note: Please note: 2021 itinerary is based on 2020 and is subject to change, but by booking today you will lock in your price. Full details will be confirmed in September 2020.
Welcome dinner at a local restaurant; guided walking tour, visit St. Mark’s Square, Doges’ Palace, and the Bridge of Sighs; glassblower demonstration; gondola serenade
MODENA [LF] Acetaia Leonardi balsamic vinegar tasting
FLORENCE Guided walking tour, visit Michelangelo’s David and Signoria Square
SIENA Guided walking tour, admire the Duomo and visit Piazza del Campo
PIENZA Visit this UNESCO World Heritage Site
ROME Guided sightseeing, visit the Vatican Museums and Sistine Chapel, St. Peter’s Square and Basilica, and the Colosseum
POMPEII Guided walking tour of the excavations
CAPRIFunicular ride; guided sightseeing, visit Augustus Gardens
SORRENTO Farewell dinner with a taste of Limoncello at a local restaurant
Plan ahead and get our best prices! Get 10% off the tour portion of your holiday when you book a 2021 Globus tour in North or South America or Europe.See all tours in offer
Inside visits and special features are shown in UPPERCASE in the tour description, including admission charges where applicable.
Total meals included:
Welcome to Venice! At 5 pm, meet your Tour Director and traveling companions for a welcome dinner at a local restaurant.
Enjoy a PRIVATE BOAT RIDE and meet your Local Guide for a walking tour. Visit ST. MARK’S SQUARE with its Byzantine basilica, lavish DOGES’ PALACE, and the BRIDGE OF SIGHS. Also watch a skilled GLASSBLOWER fashion delicate objects in an age-old tradition. Sit back and relax during LF a GONDOLA SERENADE, the best way to explore the canals. Later, on an optional excursion, discover the picturesque island of Burano.
A special treat today is a LF BALSAMIC VINEGAR TASTING at the renowned Acetaia Leonardi near Modena. Continue through the fertile Po area and the Apennine Mountains into Italy’s most popular region, Tuscany, and arrive in Florence, “Cradle of the Renaissance.” Tonight is your chance to join an optional dinner to try out Tuscan specialties.
Today’s Distance: 205 mi / 330 km
Meet your Local Guide, and visit the ACADEMY OF FINE ARTS with Michelangelo’s celebrated David. Continue your walking tour through the historic center and stand in awe in front of the the magnificent cathedral, admire Giotto’s Bell Tower and the Baptistry’s heavy bronze “Gates of Paradise,” and sculpture-studded SIGNORIA SQUARE. Afterward, you may wish to shop for Florentine leather goods and gold jewelry, sold by the ounce. Arrive in Siena, the city where the world-famous Palio, the spectacular medieval-style horse race, is held twice a year.
Today’s Distance: 62 mi / 100 km
Your guided walking tour takes you inside the historic ramparts to the PIAZZA DEL CAMPO, one of Europe’s greatest medieval squares. The Palazzo Pubblico and its Torre del Mangia surround the shell-shaped piazza. Next, drive along Via Cassia, named after the antique road leading to Rome, and stop in Pienza, famous for pecorino cheese. This picturesque town has been listed as a UNESCO World Heritage Site, thanks to a member of the Piccolomini family who became Pope Pius II in the 15th century and redesigned the town in perfect renaissance style. Tonight, in the “Eternal City,” why not sign up for an optional dinner with local specialties at one of Rome’s famous restaurants.
Today’s Distance: 155 mi / 250 km
Guided sightseeing starts with a visit to the VATICAN MUSEUMS and SISTINE CHAPEL with Michelangelo’s ceiling paintings and The Last Judgment, followed by a visit to monumental ST. PETER’S SQUARE and BASILICA to admire Michelangelo’s Pietà. Then, enjoy views of other major sites as you drive to the Roman Forum to visit the ancient COLOSSEUM, where gladiators once fought. An optional walking tour with a Local Guide is available to further explore Rome's famous sites.
Take a scenic drive southward along the Highway of the Sun. Arrive in fascinating POMPEII, the Roman city both destroyed and preserved by an eruption of Mount Vesuvius in 79 AD. Your Local Guide will walk you past patrician homes, public baths, and commercial districts that strikingly recall day-to-day life when Rome was at the apex of her power. Overnight in the charming, bayside resort of Sorrento.
Today’s Distance: 174 mi / 280 km
Speed across the glittering bay by JETFOIL to the world-famous Isle of Capri. Ride the FUNICULAR to beautiful Capri village where guided sightseeing includes a visit to AUGUSTUS GARDENS. Free time to explore the little shops on the pretty piazzetta before returning to Sorrento. The remainder of the day is at leisure, and this evening, LF farewell dinner with a taste of Limoncello at a local restaurant celebrates your Italian stay.
. Your vacation ends with breakfast this morning. The nearest airport is Naples.
It may occasionally be necessary to use alternative hotels of a similar standard to those shown.
Hotel B4 Bellini is situated in an elegant 18th-century patrician palazzo in the Cannareggio quarter, transformed into a hotel at the turn of the last century. Inside, the luxurious splendour of the 18th and 19th centuries lives on in the ancient marbles and magnificent Murano glass chandeliers, all set against rich period decor. The restaurant offers local specialties served in a dining room illuminated by splendidly decorated windows, guests can also relax comfortably and sip a cocktail in the enclosed garden. Free Wi-Fi internet access is available in all guestrooms and public areas of the hotel.
This classic Florentine style 60-room hotel boasts a great location with easy access and offers free Wi-Fi access throughout. There is a small but comprehensive fitness center, a bar and a traditional Italian restaurant featuring local cuisine and a variety of seasonal dishes.
Impressive Eight-story Hotel with contemporary interiors throughout.
A 250 room centrally located hotel in the Prati area within pleasant walking distance along the River Tiber to historic Castel Sant'Angelo. The hotel has an elegant restaurant, cozy sitting rooms, and an American bar.
The Grand Hotel Vesuvio, built and furnished in a modern style, is located in a charming position, overlooking the enchanting Bay of Naples and right opposite Vesuvius. It offers a large swimming pools with separate section for children, gardens, extensive lemon and orange groves, wide lounges, conference rooms, garage, parking, solarium, children's playground, free shuttle bus into town, 4, restaurants, 3 bars. The hotel reflects the typical Sorrentine style with ample common spaces dotted by imressive marble columns and mosaic flooring. Out of 225 rooms, 105 overlooks the see while the rest face the lavish inner garden.
Our expert Tour Directors help you get the most out of every place you visit - and have a 96% customer satisfaction rating.
We’re delighted to have achieved the Good Housekeeping Reader Recommended endorsement for customer experience.
We are a member of ABTA and our flight-inclusive holidays are protected by ATOL. If your holiday is cancelled for any reason, you’ll receive a full refund.

domain: travel


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That looks a bit fishy: Woman claims she was horrified after 'finding a live WORM in her Morrisons fish pie'
- Helen Khoiova said she was about to microwave the pie when she saw the worm
- The computer programmer, 43, from Paignton, Devon, had bought the ready meals from a Morrisons branch in Totnes, when she was too ill to cook
- A spokesman said it must have slipped through 'rigorous inspection processes'
This is the sickening moment a woman claims she saw a live worm crawling around in her ready meal.
Helen Khoiova said she was about to microwave the £5 Morrisons fish pie when she saw something frantically wriggling underneath the packaging.
She said: 'My stomach turned upside down. I could see it was moving. I will never shop there again.
Computer programmer Helen Khoiova bought the ready meal from her local Morrisons branch in Totnes, Devon, when she was too ill to cook
'It makes me feel sick just thinking of it.'
She then filmed what she said was the worm crawling around inside the packaging as proof.
The 43-year-old computer programmer explained that she had not been well so had bought the pies from a branch in Totnes so she didn't have to cook.
Disturbingly, the discovery came after she'd already eaten another pie from the same batch.
She said she was about to microwave the £5 Morrisons fish pie when she saw something frantically wriggling underneath the packaging. She said it made her feel 'sick' just thinking about it
She said she has tried to contact Morrisons CEO David Potts personally about the ready meal horror but has so far had no luck.
She now intends to complain again after the store's customer service team failed to get in touch with her.
A spokesman for Morrisons said: 'Worms occur naturally in all fish and the vast majority of the time are identified and removed during the skinning or packaging processes.
A spokesman for Morrisons said the worm must have slipped through the store's 'rigorous inspection processes'
'However, very occasionally one will slip through the rigorous inspection processes we have and it appears this was the case here.
'We will look into why this was not found.
'We will contact the customer and apologise for the inconvenience and will send them a gesture of good will.'
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domain: news


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I'm back!!! With a commission for
!! I wanted to break back in to art with something smaller with lots of rests in between. It's pathetic, really, how tough drawing is for me all the sudden. I'm really happy with how this turned out, though! I LOVE the designs, here!
I really hope you like it, ~TheTater
Image Use and Characters ©
Art © You may NOT use, upload redistribute or manipulate this art or these characters in ANY way, shape or form!! You may ONLY use this artwork if you are the commissioner!


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Jim Bundschu in the Rhinefarm vineyard, Vineburg (Sonoma), Calif., circa 1970s Rhinefarm Vineyards Cabernet Sauvignon, Sonoma Valley Vintage Reserve; Sonoma Valley Vintage Reserve Rhinefarm Vineyards Cabernet Sauvignon
Gundlach Bundschu Winery Luna Imaging, Inc. 2702 Media Center Drive Los Angeles, CA 90065-1733 http://www.lunaimaging.com)
Sonoma County Library, 211 E Street, Santa Rosa, CA 95404 https://sonomalibrary.org The Sonoma County Library makes no assertions as to ownership of any original copyrights to digitized images and can claim only physical ownership of the image(s) described in this records. However, these images are intended for Personal or Research use only. Any other kind of use, including, but not limited to commercial or scholarly publication in any medium or format, public exhibition, or use online or in a web site, may be subject to additional restrictions including but not limited to the copyrights held by parties other than the Library. USERS ARE SOLELY RESPONSIBLE for determining the existence of such rights and for obtaining any permissions and/or paying associated fees necessary for the proposed use. Preferred credit line is: Courtesy, the Sonoma County Library. Please see additional reproduction and reuse information at https://sonomalibrary.org/locations/sonoma-county-history-and-genealogy-library/order-photo .
Shows Jim Bundschu of Gundlach Bundschu Winery standing next to a century plant at the edge of a Rhinefarm vineyard. Gundlach Bundschu Winery in Vineburg, California, in the Sonoma Valley, was founded in 1858 by Jacob Gundlach as J. Gundlach & Co.; the winery closed in 1919 due to Prohibition. Between the end of Prohibition and 1970, most of the land was sold and the remaining vineyards produced grapes sold to other wineries. Jim Bundschu, great grandson of Jacob Gundlach's business partner and successor, Charles Bundschu, resurrected the winery in 1970 under the name Vineburg Wine Company, and in 1973, restored the name Bundschu Gundlach Winery. Photographer unknown. GNIS 15 Title supplied by cataloger. Local History Digital Resources Project (LHDRP) (2010/2011) Grant provided to the Sonoma County Library through the Library Services and Technology Act (LSTA) and the California State Library Services. Digitized as part of the 2010-2011 Local History Digital Resource Project sponsored by the California State Library. A version of this digital item available through the Calisphere website http://www.calisphere.universityofcalifornia.edu); a finding aid for the Calisphere collection is availble through the Online Archives of California http://www.oac.cdlib.org High resolution master image (600ppi) RGB Adobe Photoshop CS4 Macintosh
1 photographic print black and white 13 x 18 cm. image/jp2 39280640 image/tiff 8 600 Uncompressed 4000 3271

domain: history


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Privatizing public schools involves changing school words to reflect a business-like environment. There’s nothing wrong with these words in general, but when applied to schools, they change the nature of schooling and the way we look at teachers and students. Business-like terms used with schools increased during the 1980s and 1990s. They are so frequent […]
What’s Scary to Kids: Having Dyslexia and Being Held Back in Third Grade!
You thought I forgot Halloween because I posted earlier today? No. Here is an old post that is unfortunately still relevant today. There is no point in rewriting what is already said. Happy Halloween! Have fun and stay safe out there! ___________________________________________________________________ With certain states jumping on the retention bandwagon, even though we know retention […]
Special Education and Vendors–Quality Concerns
Why must school districts rely on outside companies to hire school workers in special education? Isn’t there more room for error when they hire through unregulated companies? This is a practice that appears to have started with No Child Left Behind and should fall by the wayside now that NCLB is defunct–since the Every Student […]
Who’s Accountable for Students with Disabilities When Things Go Wrong?
Now that the Every Student Succeeds Act has passed, and the power to run public schools has shifted to the local school districts and the state, will that mean more accountability on their part when things go wrong in the classroom? Consider the Peck Community School in Holyoke, Massachusetts, a public school for students with […]

domain: sociology


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Viñales – haven for nature-lovers and hikers
Viñales in the western part of Cuba, in Pinar del Rio province, is a rural town, but still one of the most popular tourist destinations of the whole country. The draw is the surrounding nature and national park, with valleys, limestone monoliths (mogotes) and tobacco fields. Viñales Valley is also on Unesco world heritage list for its natural beauty. When we visited in October, which is still considered as part of the rainy season, the nature was amazingly green and lush. The town itself is nice as well, with colorful colonial-era houses lining the narrow streets. Typically the houses have verandas in front of them, with a pair of rocking chairs for chilling out. In this post we introduce activities in Viñales and explain how to go hiking in the beautiful valleys without a tour or guide.
Viñales is first and foremost an outdoors destination – most of the activities available take place outside in the nature. Will it be horseback riding, exploring caves or hiking, the stunning nature is the thing in this rural pearl of Cuba. So don’t let the appearances fool you – when arriving in Viñales, you’ll see lines of restaurants and bars offering cheap mojitos and happy hour deals. Viñales is touristic for sure, but in a very laid-back way, and most of the visitors go there to relax and enjoy the nature, not to party. It’s also a genuinely rural town, with farming done in the old fashioned way. You’ll see oxcarts, workhorses and self-built farming tools instead of modern machines and tractors. There are cowboys with outfits that could be out of a western movie, and of course chicken running across streets and pigs oinking and taking mud baths in the courtyards.
Hiking in Viñales without tours or guides
We are not big fans of guided tours, and thus decided to skip the guided hikes and horseback riding also in Viñales. Luckily it’s well possible and totally free to head to the valleys and national park on foot, without a guide. There are not marked hiking routes tough, so you’ll need a map (and gps) to get around. We once again trusted on Maps.me offline map application, that quite well shows the dirt roads and paths around Viñales. However, we were not able to walk the route we planned in advance, because we ran into a huge mud pool that we could not find a way around, and into a stream-crossing without any kind of a bridge. Still, the hikes we made were very rewarding. It might actually be possible to hitchhike through the mud and water on a horse-back, if and when local horse-men pass by, but we didn’t try this ourselves.
Day hike in valleys around Viñales
A long day hike (19,50 km) took us to some great viewpoints, past towering mogotes in Valley of Dos Hermanas and to the Mural of Prehistory. The aim was to make a circular hike through Valle de la Guasasa valley, walking west on the northern side of Mogote del Valle and back to Viñales through Cueva de la Vaca cave. However, we needed to turn back due to a huge mud lake. First and last parts of the hike are along a main road, so you could try to hitchhike that part and make the walk shorter if you’d like. Check out this map of our hike, and utilize also Maps.me to plan yours!
Hike through Cueva de la Vaca cave
The shortest way from Viñales to Valle de la Guasasa in the northern side of the town is through Cueva de la Vaca cave. The cave is just a 1,7 km walk away from the town center, first along Calle Adela Azcuy, then through Finca Raul Reyes ranch / cafe. The path to the cave turns right after a small lake. Continuing straight and then left, you’ll find a climbing wall and a viewpoint. To reach the cave, a short climb up is needed, but it’s not too difficult. The cave is not long and very easy to walk through, but bring a torch as it’s really dark inside. On the other side the ascent to the valley is rather steep, and it seems that most of people hiking to the cave return the same way they came. However the scramble down is worth it, as the valley is very beautiful and quiet.
Our plan was to hike north until the dirt road that goes to Camino al Palmarito by the main road, but a small muddy river with no bridge over it cut our way. We actually saw a couple of cowboys going over on horses, but didn’t dare to ask if they could give us a ride. However, there are several other paths as well, and we simply walked back a bit and then turned towards the main road. Check out a map of this 8 km circular hike. This hike could be easily combined to a long day hike with the first route we introduced, if only the mud lake would be dryer (maybe during the dry season?), or if you could get a ride over it.
How to prepare for hiking in Viñales
Hiking in the valleys around Viñales is mostly very easy, and no special gear is needed, just wear sporty clothes and good walking shoes. You might need to go over or under some barbed wire fences, and getting to caves and view points requires climbing up quite steep and rocky paths. Expect the weather be hot and humid, so take a lot of water, wear a hat and use sun screen. Pack some lunch or snacks if you like, a torch for caves, and of course your phone with maps and a camera for capturing the stunning scenery.
Other activities in Viñales
Alongside hiking, horseback riding is one of the most popular activities in Viñales, and without a doubt a great way to explore the valleys and enjoy the views. With a horse it’s possible to go through muddy areas and cross streams easily, and to go further away than on foot. If you could go on your own, it would sure be fantastic, but I suppose it’s only possible to ride with a guide. However, people have reported that the guided tours are nice as well.
Another popular activities are guided tours to underground cave systems and to tobacco plantations and cigar factories. There is a large cave system around Viñales, and part of the caves are filled with water and only accessible with boat. Some caves lead through the limestone mountains, and can be accessed without guides or fees. Growing and drying tobacco leaves, as well as rolling cigars is a big business in this part of Cuba. On tours you’ll get to see and hear how all this works. We didn’t try a tour, just peaked inside a tobacco factory in Viñales, but taking pictures was not allowed.
When to go and where to stay
Viñales, as well as whole Cuba, can be visited year around, but take into account that the rainy season lasts roughly from June to November, and in autumn also hurricanes can occur. The dry season is the most popular time, and holiday seasons like Christmas time, Easter and summer bring the most visitors to the island. To avoid to crowds and enjoy the island as its most greenest, the end of the rainy season is perfect. When we visited in October, there were some rains, but not on daily basis and they only lasted for a very short time. Mostly the weather was sunny and beautiful.
The best way of accommodation in Cuba is staying in guesthouses called casa particular. These home-stays usually offer clean and nice rooms with own bathroom, and decently priced, filling meals are available too. Most of the casas are nowadays in Airbnb (join via this link and get a discount of your first stay), but you will always find one also without booking in advance. In Viñales there are hundreds of casas particulares, according to some sources even two thousand! When arriving, or already when on the way, the locals will ask if you have an accommodation already, and also the casa owners usually can and will recommend a casa of their friends or relatives in your next destination. We booked in advance only the first nights in Cuba, since we wanted to have some flexibility in our schedule, and had no issues at all with finding accommodation.

domain: geography


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Abstinence-Only Sex Ed Rears Its Head in the Trump Administration: Here's What We Should Do to Stop It
April 19, 2018
This question of when exactly the levees will break under the torrent of misinformation and mendacity of the Trump administration and sweep away the health and well-being of vulnerable populations might at first blush seem largely theoretical; however, it is anything but. Take, for instance, the Trump administration's repeated attacks on reproductive and sexual health programs, particularly around family planning and comprehensive sexual education. In a cruel, yet wholly foreseeable irony, our 45th president -- a man who has been accused of sexual assault by more than 20 women, is on his third marriage, and is currently being sued by an adult film actress with whom he likely had an affair shortly after his current wife gave birth to his youngest son -- has appointed a cadre of militant abstinence-only, anti-abortion, anti-contraception crusaders to positions of leadership within the Department of Health and Human Services (HHS).
This group, led by recently appointed acting deputy assistant secretary for population affairs Valerie Huber, has done everything in its power to roll back the objectively successful, evidence-based sexual education and family planning programs implemented by the Obama administration and replace them with programming centered on "sexual risk avoidance," which is essentially a rebranded form of abstinence-only education.
Huber has been at the forefront of the movement to resurrect abstinence-only education under the banner of sexual risk avoidance for more than a decade, serving as the president of the abstinence-only professional association Ascend (formerly the National Abstinence Education Association) and running abstinence-only education programs for the state of Ohio in the mid-2000s, which researchers at Case Western Reserve University found, "contain false information" about abortion and contraception, "misrepresent religious convictions as scientific fact," "perpetuate destructive, inaccurate gender stereotypes," and fail to provide information for LGBTQ populations.
As it concerns LGBTQ youth, Huber and other abstinence-only advocates would like the public to believe that their programming is based on "universally transferable principles" that work equally well with lesbian, gay, bisexual, transgender, and questioning teens as with their their heterosexual, cisgender counterparts. However, as recently as June 2016, Huber and Ascend released a report that used student responses to a survey to claim that teens do not want and should not be subjected to sexual education that focuses on "controversial topics," such as "LGBTQ lifestyles," "gender identity," or anything that would "promote sexual activity that causes pregnancy."
With federal sex education policy being driven by a woman who promotes the idea that the mere existence of LGBTQ individuals is controversial and that the only acceptable framing of sex is as a means to pregnancy, LGBTQ Americans are increasingly going to have to look to alternative methods of sex education. Researcher Javontae Lee Williams, M.P.H., and his colleagues at Widener University in Philadelphia have begun working on another way for the LGBT community -- particularly black men who have sex with men (MSM) -- to engage in a continuing sex ed of sorts into their 20s and 30s, covering a whole host of topics that aren't touched on in even the most comprehensive sex ed curriculums, and which can be accessed using a smartphone.
This pilot program, called Making Sex Ed Relevant, is part of the ACCELERATE! Initiative funded by ViiV Healthcare and designed to engage MSM in Baltimore and Jackson, Mississippi, in a way that builds community, reduces HIV transmission, and makes sex ed fun.
"Our approach is to center our conversation [pertaining to] black men and sexuality around pleasure. We want to say that there is joy around sex," Williams told TheBody.
Not being tethered to federal funding or the restrictions that come with working in a middle school or high school has allowed Williams and his fellow researchers to create more expansive and in-depth sex ed information.
"This program isn't designed to be Sex Ed 101", Williams said. "Our target demographic is black men ages 18 and older, particularly between 25 and 35. This is grown men having a grown men conversation that doesn't have to be filtered through the language of academia. These guys are ready for Oral Sex 301, not the basics."
The program will consist of both a more traditional toolkit with lessons to be delivered piecemeal among communities and a smartphone app that will allow users to engage with people across the country around the content that speaks to them and their sexuality, enabling them to go on deep dives with the help of trained facilitators who will be guiding the discussion. With this digital resource, the app's creators are hopeful that they can reach both geographically and ideologically isolated communities, where people may feel there is no one with whom they can be open and honest about their sex lives.
Ultimately, we all must hope that, in the near future, similar privately funded and LGBTQ-focused sex ed programs are developed, particularly with an eye toward positively impacting teens and young adults, Because, under the watchful, bigoted eye of the Trump administration, federal funding probably won't be developing them.
Drew Gibson is a freelance writer and a policy associate at AIDS United in Washington, D.C. You can follow him on Twitter at @SuppressThis or visit his blog "Virally Suppressed," which covers a multitude of issues related to public health and social justice.
This article was provided by TheBody.
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Finally, FINALLY we are real homesteaders. Before we were just playing around, thinking that canning a couple pears and owning some useless cats and a farm dog qualified us. But no longer do we have to pretend. Because… we have livestock. More specifically, CHICKENS. I have been desperate to own poultry for years now, and one of the requirements that I made when we decided to move our here was that I would get my own birds. Half the work was already done for us, because our Knob property had a massive chicken coop in good condition. To make it functional, we needed to build an enclosed yard that would keep the chickens in and chicken killers out. It’s been a long project, but I’m very happy to say that the final results should keep out even the most persistent predator.
Poll: who makes a better chicken, Ian or Lydia? Cast your vote in the comments!
Lucky for us, we had plenty of work groups come over several weeks that were able to help us with different stages of construction. Without them, the two of us would be slogging through the snow trying to get that yard done.
And suddenly…the coop was complete and move-in ready. Check back in a few days to read about our adventures buying chickens from our neighbor, releasing them into the coop, and seeing if we can get their moist little bodies to produce eggs for us after all.


Napa Valley’s newest AVA — Coombsville, designated in 2011 — is also its most significant tasting-room desert. The downtown-adjacent area is home to some top wineries and vineyards, but few are open to the public. An exception is Covert Estate, an ambitious new collaboration between three winemaking families who collectively produce four wine labels here: Azur, Empreinte, Nicholson Jones and Covert.
French-born winemaker Julien Fayard does beautiful work with Bordeaux varieties, crafting them in a plush, embracing style with serious backbone, much like his mentor Philippe Melka. But he has equal passion rosé — a passion he inherited from his family, owners of Château Sainte Marguerite in the rosé capital of the world, Provence.
The dramatic winery, which is indeed covert — its striking, ultra-modern building is hidden within a hill — features a lavish tasting lounge next to the cellar. The view over the chilly, misty Coombsville region is gorgeous. Tasting experiences here, led by hospitality director Kristi Devine, last about an hour and a half, including a tour, and typically include wines from all four labels. Guests can choose between two price tiers. For $35 per person, you’ll taste wines ranging in price from $32 to $250, and for $75 you’ll tastes wines from $75–$250. Either way, it’s a pricey experience, best suited to small groups. Don’t come if you just want to taste; this is geared toward potential buyers.
WHAT TO TRY: The sleeper hit is the Empreinte Sauvignon Blanc. On paper, it sounds excessive: $75 a bottle, aged for 18 months in new oak. But the wine has all the creamy textural lushness of oak with none of the new wood’s confectionary flavors. It’s explosively tropical, wafting lychee and yuzu, recalling a pina colada without feeling over the top.


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Britain’s ‘recovery’ went into reverse today, a “stunning blow to the Government” according to the Evening Standard. Howard Archer of IHS Global Insight said: “This is a stunningly bad outcome”. Hetal Mehta of Daiwa Capital Markets Europe said: “This is an absolute disaster for the economy”.
George Osborne said: “There is no question of changing a fiscal plan that has established international credibility on the back of one very cold month. That would plunge Britain back into a financial crisis. We will not be blown off course by bad weather”.
Baldrick Osborne might well have said: “I have a cunning plan” or perhaps “Crisis? What crisis”.

domain: economics


Your Local Scheme
Guinevere Road Neighbourhood Watch scheme. I am starting this due to the recent attempted break in of our shed in Guinevere Road, and to let other people that live in the road that we will all look out for each other. Our first priorities will be to lobby the council to install anti-theft measures from our road into the King George V Playing Field.
- the scheme doesn't have a website


text:
We theoretically and experimentally investigate a time-domain digital pre-equalization (DPEQ) scheme for bandwidth-limited optical coherent communication systems, which is based on feedback of channel characteristics from the receiver-side blind and adaptive equalizers, such as least-mean-squares (LMS) algorithm and constant or multi- modulus algorithms (CMA, MMA). Based on the proposed DPEQ scheme, we theoretically and experimentally study its performance in terms of various channel conditions as well as resolutions for channel estimation, such as filtering bandwidth, taps length, and OSNR. Using a high speed 64-GSa/s DAC in cooperation with the proposed DPEQ technique, we successfully synthesized band-limited 40-Gbaud signals in modulation formats of polarization-diversion multiplexed (PDM) quadrature phase shift keying (QPSK), 8-quadrature amplitude modulation (QAM) and 16-QAM, and significant improvement in both back-to-back and transmission BER performances are also demonstrated.
© 2014 Optical Society of America
With the advent of high speed digital-to-analog converter (DAC), signal generation based on DAC becomes an attractive method due to the simple configuration and flexible signal generation capability, and it has been attracting a great deal of interest in recent years for the transmission of 100G and beyond [1–8]. DAC for signal generation allows the software-defined optics (SDO) with arbitrary waveform generation, which can be used for signal software switch in different modulation formats [1–6]. On the other hand, it also allows the digital signal processing (DSP) at the transmitter side (Tx) with pre-compensation or pre-equalizations [3–10]. One of the first electronic pre-equalization technologies for chromatic dispersion was demonstrated in 5,120 km transmission for a 10 Gb/s Differential Phase Shift Keying (DPSK) system . In order to achieve high speed signal generation, the industrial research communities have made great effort to increase the bandwidth and sample rate of DAC.
However, the 3-dB analog bandwidth of state-of-the-art DACs is still much less than the half of its sample rate, which means that the generated signals suffer the distortions caused by the bandwidth limitation, especially for generated signals with high baud rate. Meanwhile, when it operates at high baud rate, other opto-electronic devices, such as the electrical drivers and modulators which work beyond their specified bandwidth, can further suppress the signal spectrum. Due to such cascade bandwidth narrowing effect, the system performance is seriously degraded by inter-symbol interference (ISI), noise and inter-channel crosstalk enhancement [5–8]. Electrical domain pre-equalization for the bandwidth-limitation impairments, which is a well-known technique in optical communication, has been widely utilized in recent publications [5–8, 10–17]. The first pre-equalization of the filtering penalty for the 43 Gb/s optical DQPSK signals is reported in  using DAC. In previous works [5–8], zero-forcing frequency domain equalizations are carried out to pre-equalize the linear band-limiting effects. The inverse transfer function of DAC and other opto-electronic devices is measured by calculating the fast Fourier transform (FFT) of both transmitted and received binary data using a known training signal sequence. However, from the perspective of system implementation, such approach may not be easily utilized in current 100G or 400G systems since an additional DSP block at the receiver needs to be developed to deal with the channel estimation. Furthermore, to remove the fluctuation caused by signal and noise randomness, more than 100 measurements are required to be carried out for averaging [6–8]. Also, a strict time-domain synchronization is also required in . On the other hand, to increase the measurement accuracy in the high frequency region, the spectrum of the De Bruijin binary PSK signal needs special process with pre-emphasized .
Alternatively, a time-domain pre-equalization method can be a good solution [11–17]. In most band-limited systems, adaptive equalizers are used for ISI equalization at the receiver side (post-equalization). Theoretically, in a zero-ISI system, the receiver-side linear adaptive equalizers approach the channel inverse within the sampling rate of equalization taps, to compensate the bandwidth limitation [11–24]. In fact, this channel inverse is also effective for pre-equalization. It is worth noting that, we use the channel here describing the transfer function of the transmitter hardware, but not the outside plant of the transmitter. The linear equalizers used in the receiver side is a good tool for channel estimation, which has been employed in digital cable television (CATV) and wireless transmission system for pre-equalizations [11–14]. Significant signal BER gain can be obtained using this method. Numerical results in  also show that the pre-equalization outperforms post equalization-only in band-limited system with narrowband filtering impairments. In optical coherent communication system, such as constant modulus algorithm (CMA), multi-modulus algorithm (MMA) or decision-directed least-mean-squares (DD-LMS), these adaptive equalizers’ transfer function is naturally modeled with the inverse Jones matrices of the channel [24–26]. However, when there is no polarization mode dispersion (PMD), the frequency response of these adaptive equalizers is just the inverse transfer functions of the channel. With this feature in mind, one can simply get the inverse of channel transfer function for pre-equalization. Since the adaptive equalizers are blind to the data pattern, different with the scheme used in [5, 6], there is no need to do data pattern alignment. Only clock recovery is need for symbol synchronization. Compared to the prior arts, the proposed method, featuring no additional DSP, no precise symbol alignment, is advantageous for system implementations. Using this scheme, recently we have demonstrated the improved performance for DAC generated signals . We also realized a band-limited 480-Gb/s dual-carrier PDM-8QAM transmission and have demonstrated the BER performance improvements by experimental results in .
In this paper, we extend our study by both theoretical analysis and experimental demonstration on this digital pre-equalization (DPEQ) scheme for bandwidth-limited signals in optical communication systems. The linear pre-equalization is based on the receiver-side blind and adaptive equalizers for channel estimation, such as least-mean-squares (LMS) algorithm and constant or multi- modulus algorithms (CMA, MMA). Based on the proposed channel estimation scheme, we theoretically and experimentally study the DPEQ performances under different implementation conditions, such as filtering bandwidth, taps length and OSNR. For bandwidth-limited systems, improved bit-error ratio (BER) performance can be obtained by using DPEQ compared with post-equalization only scheme. As a proof of the concept, the performance improvements by DPEQ are demonstrated by both simulation and experiment results. By using the high speed 64GSa/s DAC with pre-equalization, both improved back-to-back and transmission BER performances of 40-Gbuad polarization-diversion multiplexed (PDM) quadrature phase shift keying (QPSK), 8-quadrature amplitude modulation (QAM) and 16-QAM are obtained.
2. The principle of digital time-domain pre-equalization based on receiver-side adaptive equalizer
2.1 The principle of DPEQ
Figure 1 shows the principle of the proposed pre-equalization by leveraging the estimated inverse channel given by the receiver-side adaptive equalizer, which comes with two stages. The first stage is the channel estimation, where a data X(t) without pre-equalization is transmitted and passes through the channel H(t). The channel is band-limited with a channel response of H(t), which cause the signal distortion with ISI due to the narrow filtering effect. In a coherent optical system, such channel response H(t) represents an end-to-end transfer function taking the analog bandwidths of the DAC, the driver, the modulator at the transmitters, and that of the photo-detector and the analog-to-digital convertor (ADC) at the receivers into consideration. Again, it is worth noting that, we use the channel here describing the transfer function of the transmitter hardware, but not the outside plant of the transmitter.
Assuming the noise n(t) is additive white Gaussian noise (AWGN), then the received signal can be expressed as21–23], to compensate the channel distortion, we can employ a linear filter with adjustable taps to equalize the received signal24]. These two algorithms are widely adopted in optical coherent communication system. Since CMA- and LMS-based equalizers take both ISI and noise into account in the filter taps updating, the final goal is to find the optimal filter Q(t) having minimum MSE. In our case, we can minimize the noise in order to obtain the exact channel response. Assuming the noise n(t) is small and negligible, we can remove the noise part in Eq. (2) and have
Considering the common CMA or DD-LMS equalizer in coherent optical communication system, in which four T/2-spaced FIRs are used as the channel equalizer with T-spaced updating and detector loop. The error function is approaching zero during the convergence, therefore, ISI can approach zero at the T sampling points when noise is negligible.
Since only T sampling points are calculated during the updating and convergence, the output symbols of equalizer Q(t) after convergence (ISI is 0 at the T sampling points) can be expressed asEqs. (3) and (4), we have
Here the H(f) is the frequency response of the bandwidth-limited channel. It shows that the frequency response of the equalizer is the inverse of the channel response H(f) within the Nyquist bandwidth when the noise is negligible. In this way, for the T/2-spaced DD-LMS with T-spaced detection and updating loop, the channel response within Nyquist bandwidth can be estimated, otherwise, it approaches 1. Therefore, a time-domain pre-equalization method can be employed based on the receiver-side adaptive equalizer. For optical coherent transmission system, one can simply records the FIR tap coefficients the output of those commonly-used linear equalizers (such as CMA, CMMA and DD-LMS equalizers), and feedback that information to the transmitter for pre-equalization.
Note that the analysis above excludes the factor of noise, which, however, represents in real systems. On the other hand, as analyzed in [21–23], the performance of channel estimation by adaptive filter is significantly affected by the filter taps length and also the OSNR in channel. Therefore, considering all the factors, the channel inverse calculated by adaptive filter taps is a function of channel response, noise level, taps length, which can be expressed as
As analyzed in [21–23], the benefit of the pre-equalization can be proved by the smaller MSE of the recovered signal compared with post-equalization-only case in symbol detection systems. Assuming filter taps is long enough and the step size is small enough, one can obtain an optimal filter taps, which has the minimum MSE based on the MMSE criterion algorithms as
Therefore, the minimum MSE of pre-equalization case is smaller than post-equalization only case when the channel is bandwidth limited with narrow filtering effect. Lager gain can be obtained using the pre-equalization for narrower filtering bandwidth. Equation (8) gives a qualitative analysis of the factors that affect the estimation results. The estimated channel response is determined by the OSNR, taps length and bandwidth. The required OSNR or taps length can be different under different BER tolerance and different channel response. One should adjust and optimize these factors for practical use.
2.2 Implementation of DPEQ for coherent optical system
Figure 2 shows the principle of channel estimation for the proposed DPEQ at the transmitter. The linear pre-equalization is based on the receiver-side blind and adaptive equalizers for channel estimation. We first use the DAC to generate the mQAM data without pre-equalization for channel estimation. Since the bandwidth limitation impairment is mainly caused by the DAC, the electrical drivers, the modulator, the receiver-side PDs and the analog-to-digital converter (ADC), only single-polarization signal is used to avoid the polarization crosstalk. One continuous-wave (CW) lightwave external-cavity-laser (ECL) is used as both the signal source and the local oscillator (LO) for the self-homodyne coherent detection. In this case, the traditional post-equalization methods for polarization demultiplexing, e.g., CMA and DD-LMS, are actually the channel equalizers for the bandwidth limitation impairment, which can be used for channel estimation. The amplitude frequency response of these equalizers is the inverse transfer function of the channel. The DD-LMS loop, which is after CMA for pre-convergence, consists of four complex-valued, N-tap, finite-impulse-response (FIR) filters for equalization. After convergence, these FIR filters achieved the steady state. After normalization and frequency symmetrization, the time domain FIR for pre-equalization can be regenerated. It is worth noting that, although the m-QAM data is used as training sequence, we do not need to know the symbol information. The only information needed for the training sequence is the modulation formats. On the other hand, as analyzed in section 1, in order to get the highly accurate channel response, we should keep the noise negligible. Thus, the channel estimation can be implemented under high OSNR condition using back to back (BTB) measurement. Since the channel estimation is based on the commonly-used linear equalizers in regular coherent receiver-side DSP, the proposed method, featuring no additional DSP, is promising for system implementation.
3. Numerical simulation results
To investigate the performance of DPEQ for band-limited signal in optical coherent system and the impact of different implementation conditions, such as the filtering bandwidth, OSNR, receiver-side adaptive equalizer tap length, step value and modulation formats, a numerical simulation model is firstly setup to emulate various operating situations. The system setup configuration consists of both DSP units and electro and optical components at transmitter (Tx) and receiver (Rx) sides for the DPEQ.
3.1 System model setup
Figure 3 shows the numerical simulation model setup for DPEQ based on receiver-side adaptive equalizer using commercial optical simulation software. The input data consists of 4 components (Real and imaginary data in X and Y polarizations). These data components drive two I/Q modulators for signal modulation. The data components are generated by using Tx DSP without and with DPEQ as shown in Fig. 3. For data without DPEQ, the data components are generated by mQAM mapping. For DPEQ case, a time-domain pre-equalization is applied by convolution with a FIR, which is the inverse of channel response. The I/Q modulators are ideal with two parallel Mach-Zehnder modulators, which are both biased at the null point and driven at linear region. The phase difference between the upper and the lower branch of the I/Q modulator is controlled at π/2. After modulation, the two polarization signals are combined and transmitted together.
As a proof of concept, we use two pairs of low-pass filters (totally 4 LPFs) after data generation to simulate the bandwidth limitation effect. The LPFs are identical, which are general 3-order Bessel low pass filter with adjusted 3-dB bandwidth. Except the LPFs, other components, such as the driver and I/Q modulator, are ideal without any bandwidth limitation. The electrical drivers are identical and ideal without noise figure. One external cavity laser (ECL) is used as the light source with the linewidth of 100 kHz. The AWGN is added after the polarization multiplexing with different OSNR value.
For the receiver-side, the polarization and phase diversity coherent detection is employed using one polarization diversity optical hybrid and four balanced photo detectors (PDs). One ECL is used as local oscillator (LO) at the same frequency of ECL used in the Tx and linewidth of LO is also 100 kHz. The balanced PDs are based on PIN model with 1 A/W responsivity and 10 × 10−12 A/(Hz)0.5 thermal noise figure. The bandwidth of the PDs is wide enough with 1x baud rate pass-band. The analog to digital converter (ADC) is ideal with 2x sampling rate. After that, the receiver-side DSP is applied based on the regular optical digital coherent DSP blocks [24–26], including clock recovery, the channel equalization and polarization demultiplexing based on T/2 CMA and DD-LMS and carrier recovery. The bit-error-ratio (BER) is measured after the equalizations and decision. In simulation, the data baud rate is set at 32-Gbaud. Errors are counted over 1 million bits, and OSNR is loaded with 0.1-nm noise resolution bandwidth in the simulation model.
For pre-equalization, the implementation is based on the scheme proposed in Section 2.2, where the channel estimation is based on the filter taps of adaptive equalizer (CMA or DD-LMS) under the high OSNR, single-polarization, self-coherent detection conditions. Since the four LPFs are identical, the channel estimation for X polarization. is the same with Y polarization. We can use the same FIR for the four port Xi, Xq, Yi and Yq data pre-equalization. As analyzed in Section 2.1, the channel estimation performance is a function of channel bandwidth, tap length, and OSNR. Therefore, in the following simulations, we will study the impact of these key factors.
3.2 DPEQ performance under different LPF bandwidth
We first study the DPEQ performance of the 32-GBaud PDM-QPSK signals under different LPF bandwidth and compared with those in the post-EQ only case. To simulate the bandwidth limitation effect, we set the LPFs under different one-sided 3-dB electrical bandwidth (EBW). To obtain the channel response, we use the channel estimation method proposed in Section 2.2 based on the DD-LMS.
Figure 4(a) shows the transfer function of the LPF with 7-GHz EBW. Figure 4(b) shows the frequency response of CMA/ DD-LMS and also the regenerated FIR for pre-equalization. The ideal channel inverse of 7-GHz EBW LPF is also plotted in Fig. 4(b). The DD-LMS taps response is calculated under 45-dB OSNR and the taps length is 33. The updating step size is set at 5 × 10−4. From Fig. 4(b), we can see that the taps response matches well with the ideal channel inverse using our proposed channel estimation method. Therefore, we can use the generated FIR for pre-equalization based on the response of DD-LMS. For QPSK signal, the response of DD-LMS is the same with that of CMA since the constellations of QPSK are within the same modulus. Figures 4(c) and 4(d) shows the magnitude and phase frequency response of DD-LMS taps. We can see that, the phase of the DD-LMS taps is linear. The FIR response shape is liked “M” in Fig. 4(b). It is determined by the adaptive equalization scheme used. The T/2-spaced FIR taps are used; therefore, the frequency response can cover a 2 Nyquist frequency range (from −32 to 32GHz for a 32GBuaud signal). However, since only T sampling points are calculated during the updating and convergence, zero–ISI needs only to be achieved at the sampling points and thus the response of the FIR approaches the channel inverse only within the Nyquist bandwidth.
Figure 5 shows the signal spectrum of the 32-GBaud QPSK signals under different stages without and with pre-equalization. The spectrum of ideal 32-Gbaud QPSK signal without bandwidth limitation is shown in Fig. 5(a). The spectrum of the 32-Gbaud QPSK signal under 7-GHz LPF is shown in the Fig. 5(b). Figures 5(c) and 5(d) shows the signal with pre-equalization using time-domain FIR shown in Fig. 4(b) before and after the 7-GHz LPF. We can see that, the high frequency components within the Nyquist bandwidth is enhanced after pre-equalization.
Figure 6(a) shows the back-to-back (BTB) BER results of the 32-GBaud PDM-QPSK signal without and with DPEQ under different filtering different filtering bandwidth (7-GHz and 9-GHz EBW). Without pre-equalization, the system performance suffers degradation caused by ISI under significant bandwidth limitation as analyzed in Eqs. (9)–(11). There are about 4.5-dB and 2.5-dB OSNR improvements for signal generation using proposed DPEQ for 7-GHz and 9-GHz filtering, respectively. Insets (i) and (ii) show the eye diagrams of recovered signal without and with DPEQ for 7-GHz EBW filtering under the OSNR of 16 dB.
Figure 6(b) shows the OSNR penalty at BER of 1 × 10−2 for 32-GBaud PDM-QPSK without and with DPEQ under different filtering bandwidth from 4 GHz to 16 GHz. Inset (i) shows frequency response of generated FIR based on the estimated channel inverse using DD-LMS under different filtering bandwidth. We can see that, the OSNR penalty increase with the decrease of LPF bandwidth. The OSNR penalty can be larger than 6-dB when the EBW of LPF smaller than 6 GHz. However, the OSNR penalty in the DPEQ case is still lower than 2 dB even though the EBW is as small as 4 GHz. When using the proposed DPEQ method, the OSNR penalty is lower than 0.5 dB for EBW of LPF lager than 6 GHz. From the results, we can see that, large OSNR improvement can be obtained by using the proposed DPEQ method. These simulation results are in good agreement with the theoretical analysis in Section 2.1.
3.3. The impact of adaptive equalizer taps length
As analyzed in Section 2, the inverse channel calculated by adaptive filter is affected by the tap length. In practice, the taps length should sufficiently large enough so that the equalizer spans the length of ISI. However, since the FIR has a finite length, the linear equalizer cannot completely eliminate ISI. However, as the length of taps L increase, the residual ISI can be reduced. Therefore, the inverse channel estimation can be more accurate with longer tap length.
Figures 7(a)–7(d) show the frequency response of the DD-LMS taps compared with the ideal channel inverse of the LPF with 7-GHz EBW with different taps length in channel estimation. For the 5- taps DD-LMS, the response difference is even larger than 5 dB at the frequency of ± 16 GHz ( ± 0.5 Baud rate). We can see that, with the tap length increases, the frequency response of DD-LMS matches the ideal channel inverse closer and closer, especially at the high-frequency response within the Nyquist bandwidth.
The pre-equalization performance of the FIR generated by different length of DD-LMS tap under different channel filtering bandwidth is also studied as shown in Fig. 6(e). Here, the DD-LMS taps response is calculated at 45-dB OSNR and the taps updating step size is set at 5 × 10−4. The tap length is only changed for channel estimation and DPEQ FIR generation. The OSNR after pre-equalization is kept at 14 dB. For BER measurement, the post equalization for all cases is the same with 33-taps DD-LMS. Therefore, the performance differences are only influent by the channel filtering bandwidth and the channel estimation tap length. We can see that, for 7-GHz channel filtering, the required DD-LMS taps length should larger than 13 for channel estimation and DPEQ FIR generation. For 9-GHz, 9 taps DD-LMS is enough for channel estimation. However, for 6-GHz filtering, the required taps length should be larger than 17. That is, for narrower channels, the required tap length for channel estimation at the adaptive equalizer would be larger. This is because the tap length should be large enough so that the equalizer can cover the length of ISI in order to obtain accurate channel estimation.
3.4. The impact of OSNR on channel estimation
As analyzed in Eqs. (6) and (9) of Section 2.1, we know that the noise should approach 0 to get the exact inverse channel by using an adaptive equalizer. However, in practice, the noise always exists and cannot be removed. Therefore, the frequency response of adaptive equalizer by MMSE method always has difference with the ideal channel inverse. In this section, we study the impact of the OSNR on channel estimation in simulation.
Figure 8(a) shows the frequency response of generated FIR based on the DD-LMS taps at different OSNR for channel estimation. As analyzed in Eq. (9), the frequency response of the adaptive equalizer is the inverse of noise-loaded band-limited channel added with noise power. Therefore, as shown in Fig. 8(a), the frequency response of FIR under low OSNR is far away from the ideal channel inverse due to the large noise power, especially for high-frequency components with in Nqyuist bandwidth. Here, we keep the DD-LMS with a tap length of 33 and the updating step size of 5 × 10−4. When the channel estimation is under OSNR of 13dB, the frequency response difference compared with ideal channel inverse is larger than 6 dB at the frequency of ± 16 GHz ( ± 0.5 Baud rate). The difference decreases with the increase of OSNR for channel estimation. These results are in good agreement with analysis in Section 2.1. Figure 7(b) shows the BER performance of DPEQ based on channel estimation at different OSNR for different channel filtering bandwidth. The BER of 32-GBaud PDM-QPSK signal with DPEQ is measured at a fixed OSNR of 14 dB. Figure 7 reveals that, first, the DPEQ performance is improved with the increasing of OSNR for channel estimation. It can be proved by the results in Fig. 7(b) and also the analysis in Section 2, since the response of DPEQ approaches the ideal channel inverse with the decreasing of noise. Second, the noise power has more significant influence on the DPEQ performance when estimating narrower channels. We can see that, for 6-GHz filtering bandwidth, the gain of DPEQ is the highest by increasing the OSNR for channel estimation from 13 to 30 dB. Therefore, higher OSNR is required for channel estimation under narrower filtering channel bandwidth.
3.5The pre-equalization for Nyquist and super-Nyquist WDM cases
In above simulation and analysis, the ideal signals are without any spectrum shaping for WDM transmission. For practical use, one may apply nearly rectangular Nyquist for a more tight WDM system. In the Nyqusit WDM (N-WDM) system, the carrier frequency spacing is equal to the signal baud rate to form a zero guard-band frequency-division multiplexing. On the other hand, recently, the super-Nyquist WDM (SN-WDM) transmission has also attracted lots of research interest [27–31]. In the SN-WDM system, one can use narrow spectrum shaping to multiplexing the signals in frequency domain with carrier spacing less than baud rate. To realize the SN-WDM, instead of using pre-equalization to compensate the narrow filtering, one can use additional DSP in the receiver side to suppress the enhanced noise and crosstalk after regular channel post-equalization with the multi-symbol detection, such as maximum-likelihood sequence detection (MLSD). The performance of MLSD with quadrature duo-binary (QDB) processing in filtered optical communication systems, especially for the SN-WDM systems has been previously investigated in [27–31]. Here, we compare the performances with or without pre-equalization using different processing techniques in both single channel and WDM under different carrier spacing.
Using the same implementation of DPEQ for coherent system descripted in section 2.2, we can also do the pre-equalization for Nyquist spectrum shaped signals. Using the simulation setup in Fig. 3, we send the Nyquist signal with roll-off of 0 for channel estimation. Fig. 9 shows the spectrum of 32-GBaud Nyquist QPSK signals under different stages without and with pre-equalization. The spectrums of ideal 32-Gbaud Nyquist QPSK signal before and after the 7-GHz LPF are shown in Figs. 9(a) and 9(b). Figures 9(c) and 9(d) shows the signal with pre-equalization using time-domain FIR shown before and after the 7-GHz LPF, respectively.
Figure 10(a) shows the frequency response of the DD-LMS taps under the 45-dB OSNR and with tap length of 33. From Fig. 10(a), we can see that the taps response also matches well with the ideal channel inverse using our proposed channel estimation method. Therefore, we can use the generated FIR for pre-equalization based on the response of DD-LMS.
Figure 10(b) shows the BTB BER results of the 32-GBaud Nyquist QPSK signals versus OSNR in single channel and N-WDM case with or without DPEQ. The carrier spacing is kept at 32-GHz in N-WDM case. The roll-off factor is 0. We also measure the BER of N-WDM signals under the 7-GHz narrow filtering without DPEQ but using the previously reported QDB processing with MLSD as a comparison. Several conclusions can be made from Fig. 10(b). First, without pre-equalization, the system performance suffers degradation caused by ISI under significant bandwidth limitation as analyzed above. There are about 4.5-dB OSNR improvements for signal generation using proposed DPEQ for 7-GHz filtering at the BER of 1x10−3, with Nyquist spectrum shaping as shown in Fig. 9. Second, for the N-WDM case, there is about 0.5-dB penalty due to the channel crosstalk for the signals with DPEQ. Since the signals without DPEQ are greatly suppressed at high spectrum components, the crosstalk is smaller in N-WDM case. Negligible OSNR penalty is observed for the N-WDM signal without DPEQ. However, the BER performance N-WDM signal with DPEQ is still better than that without DPEQ. About 4-dB OSNR improvement are obtained by using DPEQ in N-WDM cases. Finally, compared with the results using QDB processing with MLSD, the DPEQ still shows better performances in N-WDM case with 1-dB OSNR improvement. Since the QDB processing with MLSD using additional DSP to equalize the ISI, the BER performance is better than that using only regular QPSK DSP in narrow filtering case. About 3-dB OSNR improvement can be observe under the 7-GHz narrow filtering in N-WDM case as shown in Fig. 10(b). However, it is worth noting that the QDB processing with MLSD requires additional DSP with a considerable increase in computational complexity [27–31].
The BER results of WDM signals under narrow filtering with different carrier spacing are shown in Fig. 10(c). The signal baud rate is kept at 32-GBaud, with roll-off factor of 0 and the carrier spacing is changed from 38 to 24-GHz. As shown in Fig. 10(c), the BER performance of pre-equalized signal drops quickly as the channel spacing narrows down with more severe inter-channel interference (ICI) brought by neighboring channels. Therefore DPEQ schemes are not best choice for the situation that strong ICI exists, when the channel spacing is smaller than the baud rate in super-Nyquist WDM cases. For carrier spacing larger than and equal to 32GHz (WDM or N-WDM cases), the DPEQ shows the best performances under both 7-GHz and 9-GHz narrow filtering. However, for signals in SN-WDM case with carrier spacing less than 32-GHz, the QDB processing with MLSD shows the best performance compared under the narrow filtering. Therefore, the QDB processing with MLSD shows better ICI tolerance capability for SN-WDM cases and it is widely used in previously SN-WDM reports [27–31].
4. Experiment results
As a proof of concept, Fig. 11 shows the experimental setup of the 40-Gbaud PM-QPSK/8QAM/16QAM generation based on high speed DAC with adaptive pre-equalization, transmission and coherent detection in a 50-GHz WDM grid. Eight tunable external cavity lasers (ECLs) ECL1 to ECL8 as 8 channels are used in our system with the linewidth less than 100 kHz and the output power of 14.5 dBm. The carrier-spacing of ECLs is 50 GHz. Before the independent in-phase and quadrature (I/Q) modulation, the odd and even channels are implemented with two sets of polarization-maintaining optical couplers (PM-OCs). The QPSK/8QAM/16QAM signals with 40-GBaud are generated by a 64-GSa/s DAC. The 3-dB analog bandwidth of the DAC is about 11.3-GHz. As shown in Fig. 8, the inphase (I) and quadrature (Q) data are generated by the Tx DSP blocks. The transmitted data is firstly mapped to m-QAM (m: 4/8/16), then up-sampled to 2 Sa/symbol. The pre-equalization is implemented to for the up-sampled data to compensate the bandwidth limitation impairment caused by the DAC, the drivers, the I/Q modulator and the ADC. In our case, the DPEQ is implemented and the FIR is obtained by the adaptive scheme as shown in Fig. 2. The polarization multiplexing of the signal is realized by the polarization multiplexer, which comprises a PM-OC, an optical delay line to provide a delay of 150 symbols, and a polarization beam combiner (PBC) to recombine the signal. The even and odd channels are modulated and polarization multiplexed individually. Then, they are combined by a 3-dB optical coupler. At the receiver side, the polarization and phase diversity coherent detection is employed. Here, the linewidth of receiver-side local oscillator (LO) is around 100kHz. A digital oscilloscope with the sample rate of 80GSa/s and bandwidth of 30GHz is used for analog-to-digital conversion (ADC) before offline processing.
The results of channel estimation and pre-equalization are shown in Fig. 12.First, we use the 64-GSa/s DAC generate the QPSK data without pre-equalization for channel estimation to get the channel transfer function as shown in Fig. 2. Since the bandwidth limitation impairment is mainly caused by the DAC, the electrical drivers, the modulator and the ADC, only single- polarization signal is used to avoid the polarization crosstalk. Self-homodyne coherent detection is applied using the same CW lightwave (ECL1) as both the signal source and the LO source. Figures 12(a) and 12(b) show the frequency response of 33-taps FIR filter Hxx in DD-LMS and the regenerated FIR for DPEQ, which indicates the inverse transfer functions of the channel. It is worth noting that, the same source is used in channel estimation only for convenience and also easy operation, since no frequency offset is needed for channel estimation. However, it is not the central to this technique, since the frequency offset can be compensated before the channel estimation. Other parts of the experiment, such as back to back and transmission performance measurement are done using different lasers
Figure 13 shows the back-to-back (BTB) BER performance versus the OSNR for single carrier 40-Gbaud PM-QPSK, PM-8QAM, and PM-16QAM signal with and without pre-equalization, respectively. Here, 33-taps FIR filters are used. We can see that, about 3.5dB, 2.5dB and 1.5dB OSNR improvement can be obtained at the BER of 1 × 10−3 by DPEQ based on DD-LMS method for the 40-Gbaud PM-QPSK/8QAM/16QAM signals, respectively. As a comparison, we also plot the theoretical BER curves in these figures. The BER results of signals with a previously reported frequency domain pre-equalization (FD Pre-eq) method [5, 6] are also plotted. We can see that, the results of the proposed DPEQ has similar performance with the frequency domain method, since both scheme use the signals with very high OSNR for channel estimation. On the other hand, we also observe the OSNR penalties compared with the theoretical performances. About 1.5, 2.5 and 4.5-dB OSNR penalties are observed for signals with pre-equalization compared with the theoretical curves. Since higher modulation formats require higher OSNR and they are more sensitive to the ISI, the pre-equalization shows less effective for the high modulation formats.
Figure 14(a) shows the experiment results of BTB BER results of 40-Gbaud PM-QPSK/8QAM/16QAM with adaptive pre-equalization versus the tap length N of Hxx used in DD-LMS. Here, we keep QPSK as the training data modulation format and the OSNR of these signals measured is 16, 21.5 and 25-dB for 40-Gbaud PM-QPSK, 8QAM and 16QAM. From Fig. 13, we can see that, QPSK is less sensitive to the tap length, and 9 taps is sufficient for pre-equalization. However, higher modulation formats 8QAM and 16QAM requires more taps for pre-equalization.
Figure 14(b) shows the transmission BER performance with and without pre-equalization for the 8 channels WDM PM-QPSK/8QAM/16QAM signals. The combined 8 channels WDM signals are launched into a re-circulating transmission loop, which consists of 5 spans of 85-km conventional SMF-28 with average loss of 18.5 dB and chromatic dispersion (CD) of 17 ps/km/nm, loop switches (SWs), optical coupler (OC), and Erbium-doped fiber amplifier (EDFA)-only amplification without optical dispersion compensation. In the loop, we place one wavelength-selected switch (WSS) programmed as an optical band-pass filter to suppress the ASE noise. The BER of WDM PM-QPSK, 8QAM, and 16QAM signals without and with pre-equalization versus the transmission distance is shown in Fig. 14(b). Longer distance can be achieved for signal with pre-equalization. Without DPEQ, the system performance is seriously degraded by ISI, noise enhancement and inter-channel crosstalk due to the bandwidth limitation and filtering effect. The system performance can be improved by reducing these bandwidth limiting impairments using the proposed DPEQ scheme.
Finally, we measure the DPEQ performances for the Nyquist signals in N-WDM cases. The 40GBuad Nqyuist signal with roll-off factor of 0 is generated by the 64GSa/s DAC for test. Figures 15(a) and 15(b) shows the FFT spectrum of the Nyquist signals after coherent detection and ADC sampling without and with proposed DPEQ, respectively. As shown in Fig. 15(b), we can see that the Nyquist signals are pre-compensated with flat spectrum shape with DPEQ. Figure 15(c) shows the BTB BER results versus OSNR for the Nyquist 40GBaud PDM-QPSK signals in SC and N-WDM cases without and with DPEQ. Again, improved OSNR performances can be observed by using the DPEQ scheme. Therefore, the proposed DPEQ method is also effective for the Nyquist signals in N-WDM case.
We theoretically and experimentally investigate the time-domain DPEQ scheme for bandwidth-limited signals in optical coherent communication systems. Based on the proposed channel estimation scheme, we theoretically and experimentally study the DPEQ performances under different implementation conditions, such as filtering bandwidth, taps length, and OSNR. For bandwidth-limited systems, improved BER performance can be obtained by using DPEQ compared with post-equalization only scheme. As a proof of the concept, the performance improvements by DPEQ are demonstrated by both simulation and experiment results.
This work was partially supported by NNSF of China (No. 61325002, 61250018, No. 61177071), “863” projects under grants 2012AA011303 and 2013AA010501, The National Key Technology R&D Program (2012BAH18B00), Key Program of Shanghai Science and Technology Association (12dz1143000)), and the China Scholarship Council (201206100076).
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