text:
Q: servicestack - caching a service response using redis I have a servicestack service which when called via the browser (restful) Url ex:http://localhost:1616/myproducts, it works fine.
The service method has RedisCaching enabled. So first time it hits the data repository and caches it for subsequent use.
My problem is when I try calling it from a c# client via Soap12ServiceClient. It returns the below error:
Error in line 1 position 183. Expecting element '<target response>'
from namespace 'http://schemas.datacontract.org/2004/07/<target namespace>'..
Encountered 'Element'  with name 'base64Binary',
namespace 'http://schemas.microsoft.com/2003/10/Serialization/'.

Below is my Client code:
 var endpointURI = "http://mydevelopmentapi.serverhostingservices.com:1616/";
 using (IServiceClient client = new Soap12ServiceClient(endpointURI))
 {
    var request = new ProductRequest { Param1 = "xy23432"};
    client.Send<ProductResponse>(request);
 }

It seems that the soapwsdl used is giving the problem, but I appear to have used the defaults as generated by servicestack..
Any help will be much appreciated.
Update
I was able over come this error by changing the cache code at the service end:
Code that returned error at client end:
return RequestContext.ToOptimizedResultUsingCache(this.CacheClient, cacheKey,
       () =>
       new ProductResponse(){CreateDate = DateTime.UtcNow,
                    products = new productRepository().Getproducts(request)
     });

Code that works now:
var result = this.CacheClient.Get<ProductResponse>(cacheKey);
            if (result == null)
            {
                this.CacheClient.Set<ProductResponse>(cacheKey, productResult);
                result = productResult;
            }
return result;

But I am still curious to know why the first method (RequestContext.ToOptimizedResultUsingCache) returned error at c# client?

A: But I am still curious to know why the first method (RequestContext.ToOptimizedResultUsingCache) returned error at c# client?
From what I can tell, the ToOptimizedResultUsingCache is trying to pull a specific format (xml, html, json, etc) out of the cache based on the RequestContext's ResponseContentType (see code here and here). When using the Soap12ServiceClient the ResponseContentType is text/html (not sure if this is correct/intentional within ServiceStack). So what ToOptimizedResultUsingCache is pulling out of the cache is a string of html. The html string is being returned to the Soap12ServiceClient and causing an exception.
By pulling directly out of the cache you are bypassing ToOptimizedResultUsingCache's 'format check' and returning something the Soap12ServiceClient can handle.
** If you are using Redis and creating your key with UrnId.Create method you should see a key like urn:ProductResponse:{yourkey}.html

A: Thanks for your response paaschpa.
I revisited the code and I was able to fix it. Since your response gave me the direction,  I have accepted your answer. Below is my fix.
I moved the return statement from RequestContext to the response DTO.
Code which throws error  when used via c# client (code was returning entire requestcontext):
return RequestContext.ToOptimizedResultUsingCache(this.CacheClient, cacheKey,
       () =>
       new ProductResponse(){CreateDate = DateTime.UtcNow,
                    products = new productRepository().Getproducts(request)
     });

Fixed Code (return moved to response DTO):
RequestContext.ToOptimizedResultUsingCache(this.CacheClient, cacheKey,
       () => {
               return new ProductResponse(){CreateDate = DateTime.UtcNow,
               products = new productRepository().Getproducts(request)
              }
     });


text:
Birds of the Gambia and Senegal.
Barlow, Clive, et al.
London: Christopher Helm/A & C Black, (2006. revised reprint). Octavo, paperback, colour illustrations, maps. A practical field guide to Gambia illustrated with 48 stunning colour plates, depicting each species in all its plumages. These plates are supplemented by useful line drawings and figures. The introduction provides an overview of the..... More
Wild Rwanda: where to watch birds, primates and other wildlife.
Behrens, Ken et al.
Barcelona: Lynx Edicions, 2015. Octavo, paperback, colour photographs, maps. Illustrated with over 160 spectacular photographs showcasing the region's beautiful landscapes, mammals, and birds. This guide provides the intrepid traveller with detailed maps, full chapters on biogeography and trip planning, a specialties section covering the region's best mammals and birds, and..... More
Birding Ethiopia: a guide to the country's birding sites.
Behrens, Ken, Keith Barnes and Christian Boix.
Barcelona: Lynx Edicions, 2010. Octavo, paperback, colour photographs, maps. This new site guide, which is illustrated with maps and photographs, shows where to find the remarkable birds of endemic-rich Ethiopia.	More
Threatened plants of the Cayman Islands: the red list.
Burton, Frederic J.
Kew: Royal Botanic Garden Edinburgh, 2008. Octavo, paperback and CD-ROM, colour photographs and maps. The first Red List assessment of the entire Cayman Islands flora, covering all 415 species and varieties considered to be native to the Cayman Islands. A comprehensive field guide to the unique plants of the Cayman..... More
The birds of southern Mozambique.
Clancey, Phillip A.
Westville: African Bird Book Publishing, (1996. revised edition). Octavo, paperback, colour plates, photographs, maps.	More
A birdwatchers' guide to the Canary Islands.
Clarke, Tony and David Collins.
Perry: Prion, 1996. Octavo, paperback, illustrations. Provides detailed information on birding sites on this island archipelago, each site entry giving location and access, accommodation, birding strategy and species expected to be seen. Also includes a selective bird list giving brief details on the distribution and status of the uncommon birds..... More
The birds of Zambia: an atlas and handbook.
Dowsett, Robert J. et al.
Belgium: Tauraco Press, 2008. Octavo, paperback, colour photographs, maps. This book presents detailed accounts of the more than 750 species known (among which there are 100 migrants from the northern hemisphere) in Zambia. Extensive fieldwork by the authors and many collaborators means that the maps (for all species except vagrants)..... More
Kalahari: wild Africa.
Fischer, Lorenz A. and Judith Burri.
Munich: Bucher Verlag, 2007. Large quarto, dustwrapper, colour photographs. The author and the award-winning photographer spent months in vast stretches of Africa to capture spectacular shots of animals and natural environments, places such as the Okavango Delta, Victoria Falls and the famous savannahs.	More
Wildlife in pictures.
Hayman, Craig.
Chatswood: New Holland Publishers, 2015. Quarto, dustwrapper, colour photographs. Having lived and worked as a safari guide in some of Africa's most spectacular wilderness areas, author Craig Hayman has been able to capture many dramatic and intimate moments in the lives of some of the world's most inspiring animals. This..... More
Red Data List of southern African plants.
Hilton-Taylor, Craig.
Claremont: National Botanical Institute, 1996. Quarto, laminated boards,	More
Africa on Safari.
Illman, Kym and Tonya.
Berkshire: Papadakis, 2015. Quarto, dustwrapper, colour photographs. The drama and beauty of the African plains are on full show in this superb collection of images. Photographers Kym and Tonya lllman present an intimate insight into Earth's greatest wilderness, spending thousands of hours on safari in Kenya, Tanzania, Rwanda, Botswana, Zimbabwe..... More
Relentless enemies: lions and buffalo.
Joubert, Dereck.
Washington DC: National Geographic Society, 2006. Quarto, dustwrapper, colour photographs by Beverly Joubert. The tawny lion slinks through golden grass, stealthy and sinuous, utterly concentrated on the hunt, a perfect predator awaiting only the instant when pure instinct triggers the rush, the spring, the ferocious slash of sharp claws and..... More
Animals of the Serengeti and Ngorongoro Conservation Area.
Kennedy, Adam Scott and Vicki Kennedy.
Princeton: Princeton University Press, 2014. Octavo, paperback, colour photographs, maps. Spectacularly illustrated by 146 colour photographs, this book is a remarkable look at the mammals and reptiles most likely to be encountered in the famous Serengeti National Park and Ngorongoro Crater. Accessible text coupled with an easy-to-use format, makes this..... More
Birds of Kenya's Rift Valley.
Kennedy, Adam Scott.
Princeton: Princeton University Press, 2014. Octavo, paperback, colour photographs, map. Covers four major national parks - Lake Nakuru, Lake Bogoria, Mount Longonot, and Hell's Gate - as well as smaller outstanding wildlife areas. Looks at over 300 bird species most likely to be encountered on safari in this world-famous region..... More
Wildflowers of Namaqualand: a Botanical Society guide.
le Roux, Annelise.
Cape Town: Struik Publishers, (2015. fourth edition). Octavo, paperback with plastic cover, colour photographs. Namaqualand (Afrikaans: Namakwaland) is an arid region of Namibia and South Africa. Namaqualand is justifiably famous for the floral wonderland it becomes in spring, comprising some 3,800 species, of which 28% are endemic. This book introduces..... More
A complete guide to the snakes of southern Africa.
Marais, Johan.
Johannesburg: Struik, (2004. second edition). Small quarto, paperback, colour photographs, text illustrations, maps. This detailed and comprehensive guide to the 151 snakes indigenous to southern Africa covers all essential aspects of snake biology and behaviour. This edition has been updated, revised and expanded to include at least 11 newly discovered..... More
Atlas of the vegetation of Madagascar (Atlas de La vegetation de Madagascar).
Moat, Justin and Paul Smith.
Kew: Royal Botanic Gardens, 2007. Folio, laminated boards, colour photographs, colour maps. Text in English and French. A unique publication for Madagascar with detailed descriptions of each vegetation type, illustrated with diagrams and colour photographs. This book provides an introduction to Madagascar's unique vegetation.	More
Bitter roots: the search for healing plants in Africa.
Osseo-Asare, Abena Dove.
Chicago: University of Chicago Press, 2014. Octavo, paperback, black and white photographs, maps. For over a century, plant specialists worldwide have sought to transform healing plants from African countries into pharmaceuticals, resulting in many long and enduring conflicts. In this book, Osseo-Asare draws on public records and extensive interviews with..... More
All the way home: stories from an African Wildlife Sanctuary.
Peek, Bookey.
Bowden: East Street Publications, 2007. Octavo, paperback, colour photographs. Stories from Stone Hills Wildlife Sanctuary in Zimbabwe. See also stock id [33957].	More
African safari: into the great game reserves.
Pickford, Peter and Beverly Pickford.
Oxford: John Beaufoy Publishing, (2016. second edition). Quarto, dustwrapper, colour photographs. African Safari is an exploration of all that the word safari encompasses, from journeys on horseback and dugout canoes, the quiet drifting of a balloon and the tension of waiting on foot to the smell of dung, soil and..... More
Battle for the president's elephants: life, lunacy and elation in the African bush.
Pincott, Sharon.
Auckland Park: Jacana Media, 2012. Octavo, paperback, colour photographs. Searching for something more than her high-flying executive life was offering, Sharon Pincott traded her First World existence to start a new life with The Presidential Elephants of Zimbabwe, the country's flagship clan of over 450 wild elephants. She knew nothing..... More
The essential Africa.
Poliza, Michael.
Kempen: teNeues, 2007. Quarto, laminated boards, colour photographs. Collection of magnificent photographs taken by Micheal Poliza in Southern Africa.	More
Botswana: safari companion.
Pons, Alain and Christine Baillet.
Herts: Evans Mitchell Books, 2006. Quarto, paperback, colour photographs, maps. Botswana is a landlocked country at the very heart of Southern Africa. The terrain is predominately flat to gently rolling tablelands while the Kalahari Dessert covers much of the south west. Because of a national policy of conservation, and the..... More
Complete birds of Seychelles.
Ramen, Narainsamy and Adrian Skerrett.
Mauritius: Authors, 2016. Quarto, dustwrapper, colour photographs. Highly accomplished bird photographer Narainsamy Ramen teams up with Adrian Skerrett, author of many Seychelles books. Together they have produced a grand celebration of the birds of these islands. All sixty-species that breed in Seychelles are illustrated in a wonderful Series of colour..... More
SASOL 300 easy-to-see birds.
Reynolds, Chevonne and Nicholas Tye.
Cape Town: Struik Publishers, 2015. Octavo, paperback, colour photographs and illustrations. This practical, straightforward guide to some of the most commonly seen birds in southern Africa is aimed at beginner birders, or even juniors. Less daunting than a full-blown field guide, it's handy and accessible, combining simple text with clear..... More

redpajama_set_name: RedPajamaCommonCrawl


text:
Q: Permitted function types in Pandoc filters I have a complex html document that I've read into pandoc, and I'm trying to write filters that will isolate the content I'm after. Some examples of this are dropping certain Divs entirely, or replacing Tables by just the content of their rows.
I was told on the pandoc mailing list that the existence of an instance Walkable a b => Walkable a [b] means you can also write functions of type Block -> [Block] and represnt the omitting of elements as []. This works, but I don't understand why, which is my question:
The way I understood it, the signature of walk (which turns functions into filters), (a -> a) -> b -> b, meant that using a function of type Block -> [Block] would not compile, since that doesn't fit the (a -> a) bit of the signature. Also in my understanding, the existence of instance Walkable a b => Walkable a [b] just describes how walk behaves when confronted with a list instead of a single element to apply f :: a -> a to. I don't see how it's related to what happens when f is of type a -> [a].

A: When f is Block -> [Block], as you notice, walk f won't type check. But toJSONFilter f will.  To see why, check out the source for ToJSONFilter in Text.Pandoc.JSON.  It contains the instance:
instance Data a => ToJSONFilter (a -> [a]) where
  toJSONFilter f = BL.getContents >>=
    BL.putStr . encode . (bottomUp (concatMap f) :: Pandoc -> Pandoc) .
    either error id . eitherDecode'

So we can apply toJSONFilter to a Block -> [Block] function.
How does it work? As you can see, bottomUp (which wraps a function from syb) is being used behind the scenes, instead of walk. bottomUp is defined in Text.Pandoc.Generic as
bottomUp :: (Data a, Data b) => (a -> a) -> b -> b
bottomUp f = everywhere (mkT f)

Since Block is an instance of Data, we can use bottomUp to promote a [Block] -> [Block] function to a Pandoc -> Pandoc.  f was Block -> [Block], but concatMap f is [Block] -> [Block], so we use that.
Hope that answers your question.  Note that because of the use of syb generics, this approach will not perform as well as one that uses Walk.  So there is some room for improvement in the pandoc API.

redpajama_set_name: RedPajamaStackExchange


text:
UT, Tennessee Press Association Announce 2013 Newspaper Contest Winners
View all the posts from July 19, 2013
Newspaper writers, editors, designers, and publishers won top awards today in the Tennessee Press Association's 2013 newspaper contest, co-sponsored by UT.
The Tennessean (Nashville), The Jackson Sun, the Elizabethton Star, the Manchester Times, the Standard Banner (Jefferson City), and the Herald and Tribune (Jonesborough) won the top general excellence awards at the association's awards luncheon held in Nashville.
General excellence honors are based on total points accumulated for awards in five categories, based on average weekly circulation.
This marks the fourth year in a row that The Jackson Sun has won the general excellence award. This also marks the third year in a row that The Tennessean has won in its category.
For the second year in a row, the results produced a tie. This year, the Manchester Times and the Standard Banner shared the general excellence award in their circulation category.
The Washington Newspaper Publishers Association judged a total of 1,485 entries from seventy-four of the association's 121 member newspapers. UT has co-sponsored the annual contest since 1940.
Other highlights:
The Tennessean received nine first-place honors in its circulation category, for best single feature, community lifestyles, best sports coverage, best graphics and/or illustrations, editorials, best personal column, best education reporting, best special issue, or section and best website.
The Elizabethton Star received eight first-place awards for make-up and appearance, local features, community lifestyles, best sports coverage, best spot news coverage, best business coverage, best education reporting, and best website.
The university's Edward J. Meeman Foundation honored newspapers for their accomplishments in editorial writing and public service journalism with $250 awards in the categories of editorials, best single editorial, and public service.
Newspapers receiving Meeman awards:
The Tennessean, The Leaf-Chronicle (Clarksville), The Tullahoma News, the Hickman County Times (Centerville), and The Portland Leader, editorials
The Commercial Appeal (Memphis), The Leaf-Chronicle, the Southern Standard (McMinnville), the Daily News (Memphis), and The Leader (Covington), best single editorial
The Chattanooga Times Free Press, The Daily Times (Maryville), The Tullahoma News, the Standard Banner, and the Herald and Tribune, public service
The foundation was established in 1968 at UT to fund the contests, provide professional critiques of journalists' work, and support journalism students and faculty.
Additional top winners in the overall contest:
The Chattanooga Times Free Press, for local features, best sports writing, best personal humor column, best business coverage, headline writing, and public service
The Herald and Tribune, for best single feature, community lifestyles, best spot news coverage, investigative reporting, best business coverage, and public service
The Commercial Appeal, for Sunday editions, best single editorial, best spot news coverage, investigative reporting, best news photograph, and best feature photograph
A complete list of winners is available here (pdf).
Charles Primm (865-974-5180, charles.primm@tennessee.edu)
Robyn Gentile (865-584-5761, rgentile@tnpress.com)
Tennessee Press Association


text:
Вороже́я (в верхнем и среднем течении — Левая Ворожея или Выргыргывеем; ) — река в Чукотском автономном округе России, правый приток Анадыря. Протекает по территории Анадырского района. Длина реки составляет 70 км.

Название
Русское название Ворожея происходит от одноимённой сопки, имя который связано с предсказанием погоды по состоянию облачности над её вершиной. Чукотское Выргыргывээм означает «шумная река»: выргыргын — «шум» и вээм — «река».

Описание
Начинается от слияния верховий на высоте 545 м над уровнем моря восточнее горы Выргыргыней, на Щучьем хребте. В верхней половине течёт преимущественно на юг, в нижней — на юго-запад. Впадает в Анадырь на высоте 69 м над уровнем моря напротив урочища Чукотское.

Данные водного реестра
По данным государственного водного реестра России, Ворожея относится к Анадыро-Колымскому бассейновому округу, водохозяйственный участок реки — Анадырь от истока до впадения реки Майн. Речной бассейн реки — Анадырь.

Код объекта в государственном водном реестре — 19050000112119000108607.

Примечания

Притоки Анадыря
Реки Анадырского района

redpajama_set_name: RedPajamaWikipedia


text:
La virodamina è un endocannabinoide che in vivo agisce come antagonista del recettore cannabinoide CB1 e come agonista del recettore cannabinoide CB2.

Biosintesi
Non è ancora stato chiarito come la virodamina sia prodotta, immagazzinata o degradata. Comunque la sua abilità di bloccare il trasporto dell'anandamide suggeriscono che possa condividere qualche via catabolica con quest'ultima.

La virodamina potrebbe essere sintetizzata a partire da una molecola di etanolamina legata ad acido arachidonico in posizione SN-2: questa molecola potrebbe divenire virodamina in seguito ad una reazione di transfosfatidilazione catalizzata dalla fosfolipasi D. Esiste anche la possibilità che la virodamina possa essere prodotta a partire dall'anandamide da una reazione spontanea o catalizzata enzimaticamente: è infatti possibile che la molecola vada incontro ad un riarrangiamento chimico presso la porzione di etanolamina a partire da un legame di tipo amidico ad un legame estere.

La comprensione di questi meccanismi richiede ulteriori approfondimenti.

Bibliografia
 Porter AC, Sauer JM, Knierman MD, Becker GW, Berna MJ, Bao J, Nomikos GG, Carter P, Bymaster FP, Leese AB, Felder CC. Characterization of a Novel Endocannabinoid, Virodhamine, with Antagonist Activity at the CB1 Receptor. J Pharmacol Exp Ther. 2002 Jun;301(3):1020-4. Testo completo in forma gratuita
 Markey et al., 2000.

Voci correlate
 Cannabinoidi
 Endocannabinoidi

Cannabinoidi
Eicosanoidi
Neurotrasmettitori


Product information "Tattoo Design of Japan"
Tattoo Design of Japan - Jyorai: This is an amazing book of designs from Horikoi a tattooer who has lived and worked in amongst the Yakuza for many years, who recieved his name from Horiyoshi III. The work is of the highest quality of traditional Japanese tattoo design. A truly inspiring book and an absolute must for all into Japanese tattooing. The book contains primarily full colour plates, but also has smaller sections of line drawings and photos of his work. Brilliant!!
Related links to "Tattoo Design of Japan"


Do you want your 'I do' to be the same as everyone else's 'I do'? Wouldn't you prefer yours to reflect your individuality and personal preferences? Why have the same script and wording as thousands of other couples? Instead, by working with me as your celebrant, I can help you to achieve the perfect ceremony and one which will be memorable for all the right reasons – simply because it was about you as a couple and was not just a standard script which had your names inserted at key points.
You may choose to incorporate a symbolic ritual such as hand-fasting, a rose ceremony or a sand ceremony; perhaps lighting a unity candle or 'jumping the broom'. I can guide and advise you through these options and help you to make your choices. You would not be allowed such elements within a civil marriage but there are no boundaries within a celebrant-led ceremony. Similarly, why not have your beloved pet dog with the wedding rings attached to his/her collar? After all, if your canine friend is a special part of your lives, make them a special part of your big day too!
vows you had previously made to each other. Whatever your reason for wanting to renew your vows, I am here to create the perfect ceremony.
I am delighted to also offer destination weddings, for couples who wish to celebrate their ceremony on far-flung shores but without all the anxiety which often accompany overseas marriage laws and requirements! Please contact me to find out how I can help you to have your dream wedding abroad.
In order to complete the legal formalities before a Wedding Ceremony or Civil Partnership Ceremony, you need to book an appointment at your local Register Office. Having worked previously as a Local Authority Registrar, I can guide you as to exactly what you need to do to fulfil these legal preliminaries.
From myself and all the Family we would like to thank you again for the lovely service you did for us yesterday.
Everyone was very moved by it all and we have had many comments to say it was the best funeral they had every been to.


1. WOMEN ARE CONFIDENT. I've always known women are confident, but this year I saw that confidence expressed in new and visible ways. Two examples: doctoral student Larisa Pataraia and student Mariam Perishvili showed great confidence when they stood up at Ilia University in Tbilisi, in the Republic of Georgia. In front of their peers, the U.S. Ambassador, the university president, faculty and administration. Larisa made an impassioned call to action for gender equality. Mariam spoke to the room about how she feels "good enough, strong enough, capable enough," proclaiming, "I am the only person that can define what I am and I am not cut out for; and YES, I am just good enough." How confident are you feeling? Do you know you are good enough?
2. MAKING WORK FIT INTO YOUR LIFE IS STILL NOT EASY. No matter how much we talk about it, and how many strategies myself and others give, women are still struggling to make work fit into their life goals. Work/Life balance is the topic I am asked most frequently about around the world. Yes, it's tough, but women everywhere ARE making it work and you can too. Women are making the choices that work best for them and their families, I know you are too. Here is a brief, new post I wrote sharing three additional thoughts on the topic based on the questions I was asked this year.
3. WOMEN DO SUPPORT WOMEN IN GENEROUS WAYS. I began to have my doubts about this when many women I reached out to did not respond, or promised to follow up and didn't. But I learned that when you connect with women who share your values, commitment and goals, they'll go to extremes to enable your success. We ran a crowd funding campaign this year to raise money to be able to provide copies of UNDETERRED to university students, and raised $32,000 in 17 days. Much of it was from women, including two very generous friends of mine, Darcy Howe and Teresa Kellett. Four women in particular opened the door to huge opportunities for me this year: Molly Rydzynski at the U.S. Embassy in Tbilisi, Georgia; Colleen Larsen of Business Engage in South Africa; Laura Tapia Navarro at P&G in Mexico; and Susana Robles Garcia who enabled the funding for the Spanish translation of UNDETERRED. Not only did they make speaking engagements happen for me, they attended the sessions with me, drove me around, fed me and supported me in more ways than I can ever thank them for. Who are you supporting?
4. REJECTION IS HARD. This year was as hard as it was good. For all the opportunities I had, there were plenty of others I did not get. As much as I try to figure out the lack of response, I often cannot determine the reason. So while I continue trying to learn from what doesn't go well, I am much more inclined to focus on pursing opportunities where things flow easily. I've learned that its impossible to give up when you believe strongly in what you are doing and when you have support from those who love and are aligned with your goals. So like the women I work with, I'm choosing to be undeterred!
5. MEN ARE SUPPORTING WOMEN. I walked into a university classroom in the Republic of Georgia expecting a room full of women students. Instead I was greeted by around 45 men who wanted to learn more about how they could be more supportive of the women they knew they'd be working with when they graduated. I moderated a panel with male CEOs at an economic forum in Abu Dhabi and my panelists shared what they and their organizations were doing to advance women, as well as some personal realizations about their roles as fathers, husbands and managers. In Mexico, I conducted a session for mostly male managers at P&G on how they could be more personally engaged in encouraging the success of the women on their teams. In each of these instances, I encountered men who understand the business case for the advancement of women and as importantly, they are personally committed to gender parity.
I am more inspired every day by the women and men I am privileged to meet, and people like you I connect with on thewaywomenwork.com. I end this year even more committed to my mission of unleashing the business and professional success of women around the world. I know a big part of what I do in 2016 will be to work with more men, sharing specific things they can do to help women advance and succeed in the workplace.
How about you? How was your year? What were your learnings? What does 2016 look like for you?


ESG are working with one of the most established brands in the recruitment industry with over 30 years of experience, this firm are extremely well-placed to give you the best start to your Recruitment Consultant career as a Graduate Trainee.
They have aided the digital and technological transformation of big brands, start-ups, scale-ups and blue-chip companies over the last 3 decades, enabling them to expand and grow, whilst providing unrivalled, exceptional technology talent with a highly consultative, efficient service from their Recruitment Consultants.
The IT market is fast-paced, forward-thinking and this recruitment consultancy has adapted and grown in parallel with this. With offices in 15 countries covering Europe, Asia and the USA, they currently employ circa 2000 people and they are keen to continue this growth with the addition of driven, outgoing Graduate level hires to join as Trainee IT Recruitment Consultants.
You could be working across both contract and permanent vacancies from the best Junior IT talent starting out in the industry to Senior IT appointments and C-level executive hires. They also cover roles within HR and Financial Services recognising development of teams and companies in the Digital age.
Do you think you like the idea of beginning your Graduate career here?
If so, please apply to the ESG Team with your updated CV and they will be in touch to discuss your application in more detail, if you're successful in the screening process.


text:
Celebrity News September 07, 2018
Cardi B's Sweet Words About Husband Offset at Jeremy Scott Fashion Show
Cardi B is making the rounds during New York Fashion Week.
Last night, the "Bodak Yellow" rapper sat front row at the Tom Ford Fashion Show, then showed support to her husband Offset as he walked in Jeremy Scott's show.
"Extra" spoke with Cardi B at Scott's show, where she gushed about her man. She said, "I'm a proud wife. I wish I could bring my baby and say, 'Look at your daddy.'"
She added, "I love him. He's really like a real friend to me… He's like my family."
Where was their 1-month-old bundle of joy, Kulture? The 25-year-old shared, "She's in my hotel room… my little baby."
#CelebrityNews#CardiB#Offset
MTV VMAs! Cardi B Reveals New 'Do on First Post-Baby Red Carpet
Cardi B & Offset Welcome Baby Girl — Find Out Her Name!
Cardi B & Offset Secretly Married


Do you want to make money online taking paid surveys? Here is a list of 15 best survey sites that will pay you in cash sent through PayPal.
Are you looking for money making ideas? These 16 companies will give you free sign up bonus from $1 to $10 when you become a new member.
They say that billionaires are not born, but they are made. These books will help you nurture a billionaire attitude and an entrepreneurial mind.


George School Orientation Weekend! This weekend is orientation weekend for all first year students. Students will have the opportunity to enjoy team-building activities outdoors on South Lawn on Saturday, September 8. The Club Fair will also take place on Sunday, September 9 and allow students to learn about and sign up for the clubs and student initiatives available at George School. Full Weekend Schedule.
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text:
\section{Introduction}

A large variety of topics rely on our understanding of the formation and
evolution of dwarf galaxies.  In the $\Lambda$CDM cosmology, galaxies form
hierarchically by cooling and condensation of the baryons within dark-matter
haloes that gradually merge \citep{White1978}. Strong efforts are therefore
concentrated on counting, characterising, and quantifying the impact of the earliest
and smallest of these galactic systems from the local universe to the
reionisation period \citep[e.g.][]{Tolstoy2009, Wise2014, Sawala2016,
  Simon2019, Torrealba2019}.

The Sextans dwarf spheroidal galaxy (dSph) was discovered by
\citet{Irwin1990}. At a distance of $\sim$ 90 kpc, it is one of the closest
satellites of the Milky Way \citep{Mateo1995, Lee2003, Battaglia2011}. Its late
discovery is the consequence of its large extent on the sky with a tidal radius
of $120 \pm 20$ arcmin \citep{Cicuendez2018} and low surface brightness of
$\sigma_0 = 18.2 \pm 0.5$ mag/arcmin$^{2}$ \citep{IrwinHatzidimitriou1995} making it a challenging galaxy to characterise given the large fraction of
Milky Way interlopers.

The analysis of the colour magnitude diagram (CMD) of Sextans reveals a stellar
population which is largely dominated by stars older than $\sim$11Gyr
\citep{Lee2009}, with evidence for radial metallicity and age gradients, the
oldest stars forming the most spatially extended component \citep{Lee2003,
  Battaglia2011, Okamoto2017, Cicuendez2018}.

Spectroscopic follow-up in Sextans started in 1991 at medium--low resolution in
the region of the calcium triplet (CaT, 8498, 8542 and
8662 \AA). \citet{DaCosta1991} identified six galaxy members and derived a mean
metallicity of [Fe/H] $= -1.7 \pm 0.25$ dex. \citet{Suntzeff1993} increased the
sample of galaxy members up to 43 and revised the galaxy peak metallicity to $-2.05
\pm 0.04$ dex. The enhanced multiplexing power of a new generation of spectrographs with over $\sim$ 30\arcmin\
fields of
view opened up the possibility to
analyse hundreds of stars at once. Spectroscopy in the region of the Mg I triplet
(5140-5180 \AA) and the CaT absorption features were used for rough chemical
tagging and to investigate the mass profile of  Sextans, as well as the possible existence
of kinematically distinct stellar populations at its centre
\citep{Walker2006a, Walker2009a, Battaglia2011}. Sextans is thought to be about
0.4 Gyr away from its pericentre (r$_{\rm{peri}}$ $\sim$ 75 kpc) moving towards
its apocentre (r$_{\rm{apo}}$ $\sim$ 132 kpc), and its orbit seems inconsistent
with a membership to the vast polar structure of Galactic satellites
\citep{Casetti-Dinescu2018, Fritz2018}. Until recently, no statistically
significant distortions or signs of tidal disturbances had been found down to very
low surface brightness limit \citep{Cicuendez2018}, but combined reanalysis
of the spectroscopic membership and deep photometry have revealed the presence of a
ring-like structure that is interpreted as the possible sign of a merger
\citep{Cicuendez2018b}.

One thread of studies traces the formation and evolution of galaxies by
exploring their chemical evolution as preserved in stellar abundance patterns.
Comparison between galaxies of very different star formation histories also
offers important insight into poorly understood nucleosynthetic origins such as
for the neutron capture elements
\citep[e.g.][]{Tolstoy2009,Jablonka2015,Mashonkina2017,Ji2019,Reichert2020}. Here,
spectroscopic multiplex again plays a fundamental role allowing to switch from
the pioneer ensembles of a few stars per galaxy that had elemental abundances
and abundance ratios \citep[e.g.][]{Hill1995,Shetrone2001, Shetrone2003} to
statistically significant samples.  A step forward arose from Keck/DEIMOS
medium-resolution (R$\sim$7000) spectroscopy, with about 35 Sextans stars with
delivered abundances of $\alpha$-elements (Mg, Si, Ca, Ti) at accuracies better
than 0.3 dex \citep{Kirby2011a}. This sample has recently been completed with
Cr, Co, and Ni abundances \citep{Kirby2018}. The number of remaining open
questions in Sextans is nevertheless very large. In particular, its low
metallicity range ([Fe/H]$\le -2.$) is still uncovered. Only a few extremely
metal-poor stars have been targeted in this galaxy \citep{Aoki2009, Tafelmeyer2010}. The mean
trend and scatter at fixed [Fe/H] of the abundance ratios still need to be
investigated over the full chemical evolution of Sextans.

The VLT/FLAMES fibre-spectrograph has already been transformative in addressing
similar questions in other dSphs. The Dwarf Abundances and Radial velocity team
(DART) targeted the Fornax and Sculptor dSphs \citep{Letarte2010,
  hill2019}. The present paper presents the DART high-resolution spectroscopic sample
of Sextans. In the following, we present the analysis of a sample of 81 Sextans
stars that have been observed in the central region of Sextans at high
resolution (R$\sim$20,000) with VLT/FLAMES (GIRAFFE and UVES). This is the
largest sample of red giant branch (RGB) stars dedicated to a chemical analysis, and allows us to address questions related to both stellar nucleosynthesis and galaxy
evolution.

\section{Observations and data reduction}

Our targets are RGBs located in the central
25\arcmin\  field of the Sextans dSph. About half of the sample is
composed of RGBs previously identified as Sextans members based on their radial
velocities measured from medium-resolution spectra around the calcium triplet
\citep{Battaglia2011}. The rest of the sample was selected from the
position of the stars in the CMD of Sextans. The
spatial distribution of our sample stars is presented in
Fig. \ref{Star_Location}, while Fig. \ref{CMD} displays their location along the
RGB $V$ versus $V-I$ plane.

We gathered high-resolution (R$\sim$20'000) spectra of 101 stars in the HR10,
HR13, and H14 gratings of the multi-fibre spectrograph FLAMES/GIRAFFE installed at
the VLT (ESO Program 171.B-0588(A)). The observations were conducted in three runs
from March to December 2004 and led to a total exposure time of 30 hours and 17
minutes. Two fibres were linked to the red arm of the UVES spectrograph, yielding
R $\sim$ 47 000 spectra of two stars, S05-5 and S08-229, over the
$\lambda$ $\sim$ 4800-6800 \AA\ range. Table \ref{obs} summarises the characteristics
of the gratings and the corresponding exposure times.

\begin{figure}
   \centering
   \includegraphics[width=\hsize]{Stars_location.pdf}
   \caption{Spatial distribution of the DART spectroscopic
     observations in Sextans. The grey points show the stars
     observed around the CaT survey \citep{Battaglia2011}. The blue circles
     correspond to the probable members of this medium-resolution
     sample, while the green points are the stars of our high-resolution
     sample (see Table \ref{Photo_param} for the values of RA and
     DEC).  The black ellipse represents the tidal radius of Sextans
     calculated by \cite{Cicuendez2018}.}
         \label{Star_Location}
\end{figure}

\begin{figure}
  \centering
  \includegraphics[width=\hsize]{CMD_col_zoom.pdf}
      \caption{Colour-magnitude diagram of the Sextans stars. The blue and green points are in as in Fig. \ref{Star_Location}.
      The black dots correspond to Sextans photometry taken with the CFH12K CCD camera at Canada-France-Hawaii
      Telescope  \citep[CFHT;][]{Lee2003}.}
         \label{CMD}
\end{figure}

In each MEDUSA plate, 16 (in HR10) and 19 (in HR13, HR14) fibres were
dedicated to the sky background. Five fibres were allocated to
simultaneous wavelength calibration in HR10 and HR13, but not in HR14
to prevent pollution from the argon lines which saturate at wavelength
longer than 6500 \AA. Nevertheless, in some cases these
wavelength calibration spectra have also polluted their closest
neighbour stellar spectra in HR10 and HR13.  The spectra of 25 stars are
affected by this problem; they are indicated in Table
\ref{Photo_param}. For those stars, we discarded the polluted spectra
(HR10 and/or HR13) from further abundance analysis.
Three more stars have one or two missing parts of their spectra: S05-70
and S05-78 have no HR10 spectrum and S08-274 has only a HR10 spectrum. This
information is also reported in Table \ref{Photo_param}.

\begin{table}
\small
\centering
\begin{tabular}{lccc}
 \hline
 Grating & HR10 & HR13 & HR14\\
 \hline
$\Delta \lambda$  &  $\sim$5340-5620 \AA  & $\sim$6120-6400 \AA  & $\sim$6300-6700 \AA\\
 Resolution & 19800  &  22500  &  17740 \\
 Exposure Time &  36080 s &  43566 s  & 29400 s\\
\hline
\end{tabular}
\caption{Summary of the observations: The three gratings of the GIRAFFE observations are indicated as well as their wavelength coverage ($\Delta \lambda$)  and total exposure times.
Two fibres were simultaneously connected for the total exposure time to the red arm of UVES with a central wavelength of $\sim$5800~$\AA$ and a resolution of 47000.}
\label{obs}
\end{table}

The data reduction has been performed with the ESO GIRAFFE Pipeline version
2.8.9. For each science frame, we used the corresponding bias, dark, and
flat-field frames, as well as arc lamp spectrum.  For the sky subtraction, we
used the routine of M. Irwin \citetext{priv.\ comm.}, which creates an average sky
spectrum from the sky fibres. This average sky spectrum was then subtracted from
each target spectrum after appropriate scaling in order to match the sky
features in each fibre. We extracted the individual spectra with the task
\textit{scopy} in \verb+IRAF+.  The heliocentric velocities were calculated and
possible shifts were corrected before the individual subexposures were averaged
with \textit{scombine} in \verb+IRAF+ with an averaged sigma clipping algorithm that removes remaining cosmic rays and bad pixels.

The signal-to-noise ratio (S/N) per pixel of each of our 101 spectra was estimated
with the \verb+IRAF+ task \textit{splot} in three continuum regions: [5456.6\AA
  , 5458.94\AA], [6193.47\AA , 6197.74\AA], and [6520.0\AA , 6524.4\AA] for
HR10, HR13, and HR14, respectively.  The results are presented in
Table~\ref{Atmospheric_param_from_photometry}.

The spectra were normalised with the routine of M. Irwin \citetext{priv.\ comm.}, which consists in an iterative process of spectrum filtering. The routine detects
the lines through asymmetric k-sigma clipping and they are masked to fit the
continuum.

\section{Selection of the Sextans members from the GIRAFFE sample}

We derived the stellar radial velocities from the 1D reduced spectra with
\verb+DAOSPEC+ \footnote{DAOSPEC has been written by P.B. Stetson for the
  Dominion Astrophysical Observatory of the Herzberg Institute of Astrophysics,
  National Research Council, Canada.}  \citep{StetsonPancino2008}, which
cross-correlates all the detected lines with an input line list that we took as
in \citet{Tafelmeyer2010}.  The radial velocities in each grating (HR10, HR13,
HR14) and their mean are provided in Table \ref{vrad_HR} and shown in Figure
\ref{Vrad_histo}.

\begin{figure}
  \centering
  \includegraphics[width=\hsize]{Vrad_distribution.pdf}
  \caption{Radial velocity distribution of our stars (black solid line). The
    dashed red line corresponds to the mean radial velocity from
    \citet{Battaglia2011} based on 174 probable members: $v_{sys, \ helio} =
    226.0 \pm 0.6$ km/s. The two solid red lines represent the $\pm 3 \sigma$
    interval within which the membership zone is defined.}
  \label{Vrad_histo}
\end{figure}

The Sextans members were selected by requiring that their radial velocities fall within 3$\sigma$ of the galaxy systemic velocity derived by
\citet{Battaglia2011}, $226.0 \pm 0.6$ km/s, $\sigma = 8.4 \pm 0.4$ km/s.
Twelve stars were identified as background or foreground interlopers; they are
indicated as \textit{Non-member (}v\textit{)} in Table \ref{Photo_param}. Our
final cleaned sample has a mean velocity and dispersion of v$_{\rm sys, \rm
  helio} = 224.9 \pm 1.9 $ km/s, $\sigma = 7.7 \pm 0.5$ km/s in perfect
agreement with \citet{Battaglia2011}.

The dataset has been acquired over a time period of 1 month, and this time delay between
the HR10 and HR13/HR14 spectra allowed us to look for binaries.  These  were
identified based on radial velocities derived in each grism differing by more
than 1$\sigma$, the error on the velocity. This corresponded to differences in
velocities of $\Delta$v$_{\mathrm{rad, HR}}$ between 7 and 35 km/s.  A total of
$13$ binary systems were identified in this way, for which the mean radial
velocities in Table \ref{Photo_param} are preceded by a tilde symbol. We also
identified five carbon stars with a strong C$_2$ band head. A preliminary analysis shows
that these are CEMP-s stars. Further investigation of these stars is postponed to another
paper.

Five stars (S05-72, S08-321, S08-111, S08-301, and S08-293) with overly poor-quality
spectra and very unstable solutions for their abundances have also been removed
from our investigation. These latter stars usually fall at the margins of the photometric
RGB and are classified as \textit{Non-member (c)} in Table
\ref{Photo_param}.
As a result of the above selection, our final sample encompasses 81 RGB Sextans stars.

\section{Stellar atmosphere models}

Our full sample is distributed along the Sextans RGB down to the horizontal branch
level, that is, reaching uncommonly faint magnitudes for high-resolution
spectroscopic analyses.  For that reason, the elemental abundances of the GIRAFFE
sample were derived by synthesis based on a $\chi^{2}$ minimisation procedure,
which can balance the derivation of the chemical abundances over the widest
possible wavelength range at once. This procedure is described in
Sect. \ref{synth}.  Two stars were sufficiently bright to be fed to
UVES. These have been analysed in a classical way, which is detailed in Sect. \ref{uves},
based on the equivalent widths of their individual absorption lines.

In both cases, we adopted the MARCS 1D spherical atmosphere models, which were
downloaded from the MARCS web site\footnote{marcs.astro.uu.se}
\citep{Gustafsson2008}, and interpolated using the code of Thomas Masseron available
on the same website. We assumed standard values of [$\alpha$/Fe] following the
Galactic disc and halo, namely +0.4 for [Fe/H]$\leq$ $-1.5$, $+0.3$ for
[Fe/H]=$-0.75$, $+0.2$ for [Fe/H]=$-0.54$, $+0.1$ for [Fe/H]=$-0.25,$ and $+0.0$
for [Fe/H] $\geq$ 0.0.

\section{Photometric parameters}

The photometric estimates of the stellar parameters $T_\mathrm{eff}$, \ensuremath{\log g}, and v$_{\rm turb}$\ were
based on the ESO 2.2m WFI $V$ and $I$-band magnitudes \citep{Tolstoy2004,
  Battaglia2006, Battaglia2011}, as well as on the $J$, $H$, $Ks$ WFCAM LAS UKIRT
photometry calibrated onto the 2MASS photometric system
\citep{Skrutskie2006}. These magnitudes are provided in Table \ref{Photo_param}.

For each star, the photometric effective temperature is taken as the
simple average of the four colour temperatures $T_{\rm V-I}$, $T_{\rm
  V-J}$, $T_{\rm V-H}$, and $T_{\rm V-K}$ obtained with the
calibration of \citet{Ramirez2005}.  When possible, the metallicity
estimate from the CaT was used as initial iron abundance; otherwise we
adopted the mean metallicity of the Sextans stellar population,
[Fe/H]=$-1.9$, as given by \citet{Battaglia2011}.  We used $E_{B-V}
= 0.0477$ \citep{Schlegel1998} and the reddening law, $A_{V} =
3.24\ E_{B-V}$, of \citet{cardelli1989}.  The stellar surface
gravities were estimated from the stellar effective temperature and
the bolometric correction calculated as in \citet{Alonso1999}. We
adopted a distance of 90 kpc \citep{Tafelmeyer2010, Battaglia2011}, a
0.8 M$_{\sun}$ stellar mass for our sample stars and
\ensuremath{\log g}$_\sun=4.44$, $T_\mathrm{eff}$$_\sun$ = 5790 K, and M$_{Bol, \sun} = 4.75$.
The micro-turbulence velocities were derived according to the
empirical relation v$_{\rm turb}$ = 2.0 $-$ 0.2 $\times$ \ensuremath{\log g}\ of
\citet{AnthonyTwarog2013}. The effective temperature for each colour,
the bolometric corrections and initial metallicities are provided in
Table \ref{Atmospheric_param_from_photometry}.

These photometric parameters were the final ones for the GIRAFFE sample, while
$T_\mathrm{eff}$\ and v$_{\rm turb}$\ could be further spectroscopically adjusted for the two stars
observed with UVES as described in Sect. \ref{uves}.

\section{Analysis of the two stars observed with UVES}
\label{uves}

S05-5 and S08-229 were sufficiently bright to be allocated to two of the eight
UVES fibres of the FLAMES configuration. These stars were analysed in the same
way as in our previous publications on high-resolution spectroscopic studies in
dwarf spheroidal galaxies \citep[e.g.][]{Letarte2006, Letarte2010,
  Tafelmeyer2010, Jablonka2015, hill2019}.  The abundance analysis has been
performed using the local thermodynamical equilibrium (LTE) code \textit{CALRAI}
first developed by \citet{Spite1967} (see also \citet{Cayrel1991} for the atomic
part), and continuously updated over the years. We summarise the main steps
below.

\subsection{Measurements}
\label{sec:eqw}

The absorption features were measured following the line list of
\citet{Tafelmeyer2010} which combines those of \citet{Letarte2010} and
\citet{Cayrel2004}. The equivalent widths were measured with
DAOSPEC. As DAOSPEC fits absorption lines with Gaussians
that have a fixed FWHM, the equivalent widths of strong lines with prominent wings
are systematically underestimated.  Therefore, lines with equivalent widths larger
than 180~m$\AA$ were discarded. Table \ref{tab:uves_eqw} lists the lines and their equivalent widths.
The present analysis focuses on the elements derived in the HR10, HR13, and
  HR14 grisms. A discussion of the other elements accessible thanks to the
  UVES wavelength coverage and high resolution is deffered to a forthcoming
  paper.

\subsection{Final atmospheric parameters and error estimates}
\label{sec:specparams}

The convergence to our final effective temperatures and the microturbulence
velocities (v$_{\rm turb}$) presented in Table \ref{Stellar_param} was achieved
iteratively, as a trade off between minimising the trends of metallicity derived
from the \ion{Fe}{I} lines with excitation potentials and equivalent widths on the one
hand and minimising the difference between photometric and spectroscopic
temperatures on the other hand.  Starting from the initial photometric
parameters we adjusted $T_\mathrm{eff}$\ and v$_{\rm turb}$\ allowing for deviation by no more than 2
$\sigma$ (the uncertainty) of the slopes. This yielded new metallicities which
were then fed back into the photometric calibration to get new photometric
temperatures and gravities.  No more than two or three iterations were needed to
converge to our final atmospheric parameters.

The predicted equivalent widths rather than the observed ones were considered in
this procedure, because the errors on the measurements can bias the slope of the
diagnostic plots \citep[see][]{magain84}. However, the surface gravities were kept
fixed to their photometric values due to the small number of \ion{Fe}{II} lines
and possible NLTE effects, which might affect the ionisation equilibrium.

The final abundances are calculated as the weighted mean of the abundances
  obtained from the individual lines, where the weights are the inverse
  variances of the single line abundances. These variances were propagated by
  \textit{CALRAI} from the estimated errors on the corresponding equivalent
  widths. They are listed in Table \ref{tab:UVES_abund}. Table \ref{tab:atmoerr} provides the errors on the abundances linked to the
  uncertainties on atmospheric parameters for the two stars observed with UVES.

\section{Analysis of the GIRAFFE sample}
\label{synth}

\subsection{Synthetic grid}

\noindent {\bf [Fe/H]:} To determine [Fe/H], a library of synthetic spectra covering the HR10, HR13, and
HR14 wavelength regions was created with \verb+MOOG+ \footnote{ \texttt{MOOG}
  \citep{Sneden1973} is a \texttt{FORTRAN} code designed to perform a variety of
  LTE line analyses and spectrum synthesis with the aim being to help with determination of the stellar
  chemical composition. The basic equations of the stellar line
  analysis in LTE are used following the formulation of Edmonds (1969).  Much of
  the \texttt{MOOG} code follows in a general way the \texttt{WIDTH} and
  \texttt{SYNTHE} codes of R. L. Kurucz (http://kurucz.harvard.edu/).} (August
2010 Version). The stellar spectra were generated at the resolution R=40000,
over  4200K $\leq$ $T_\mathrm{eff}$ $\leq$ 5300K  with a step of 50
K,   0.5 $\leq$ \ensuremath{\log g} $\leq$ 2.5 with a step of 0.1 dex,
 $1.4 \leq$ v$_{\rm turb}$ $\leq 2.0$ with a step of 0.2 km/s,
and  $-4.0 \leq $[Fe/H] $ \leq -0.5$ with a step of
0.1 dex.\\

\noindent {\bf Elemental abundances:} To derive the other elemental abundances,
          [X/H], we created two sets of synthetic spectra at given
          $T_\mathrm{eff}$, \ensuremath{\log g}, v$_{\rm turb}$, and [Fe/H]. The
          first set of synthetic spectra covered an interval of 6 dex in [X/H],
          from [X/H] $= -5.0$ to [X/H] $= 1.0$ , in $0.5$ dex steps. The second
          set covered only 2 dex in [X/H] but with steps of $0.05$ dex and was
          centred on the first estimated [X/H] of the star under analysis. \\

The resolution of the synthetic spectra was adjusted to those of the observed
spectra, i.e. to resolving powers $R=19800$ for HR10, $22500$ for HR13, and
$17740$ for HR14, by convolution with Gaussians with FWHM=$15.2$, $13.3$, and
$16.9$~\kms, and was then normalised with \verb+MOOG+. A number of different
macroscopic mechanisms can broaden the stellar absorption features. The dominant
one in our case is the instrumental broadening. However, as is often the case,
applying this instrumental broadening to theoretical spectra is insufficient.
Macro-turbulence and possible rotation need to be taken into account.  These
corrections were estimated on the four brightest stars of the GIRAFFE sample for
which both a classical analysis based on line equivalent widths and the spectral
synthesis could be independently performed (see Sect. \ref{eqwsynth}). For this
particular purpose, we only considered the \ion{Fe}{I} lines. We found that an
additional broadening by $\sigma$=9.0 km/s, 7.9 km/s and 7.6 km/s Gaussians for
the HR10, HR13, and HR14 gratings, respectively, resulted in the best agreement
in metallicities between the two types of analyses.  These broadenings were
therefore applied to the synthetic spectra for the three respective setups.

\subsection{Synthesis principles}

The elemental abundances of the GIRAFFE sample stars were  derived by
synthesis based on a $\chi^{2}$ minimisation procedure, in which
\begin{equation}
\chi^{2} = \sum\limits_{i=1}^N  \dfrac{(y_{\rm obs, i} - y_{\rm mod, i})^{2}}{y_{\rm mod, i}}
 \end{equation}

where $i$ is the pixel index and $y$ the normalized flux of this pixel in the
observed $y_{\rm obs, i}$ spectrum as well as in the model synthetic $y_{\rm mod,
  i}$ one.

For each chemical species, a global $\chi^{2}$ was calculated for all detected
lines. The match between the synthetic and observed spectra was estimated in
windows centred on the lines with widths of 22 pixels in HR10 and HR13 (1.05\AA), and
28 pixels (1.35\AA) in HR14. The width of these windows were calculated as 1.75
$\times$ FWHM, with FWHM being the spectral resolution of the grating under
consideration.

The final $\chi^{2}$ value was summed over the lines in the three wavelength bands :
\begin{equation}\label{eqn:chi2_tot}
\chi^{2}_{\rm tot} = \left( \sum\limits_{\rm HR10} \chi^{2}\right) \ + \left(\sum\limits_{\rm HR13} \chi^{2}\right) \ + \left(\sum\limits_{\rm HR14} \chi^{2}\right)
\end{equation}.

\subsection{Iron abundance}

Starting from the \ion{Fe}{I} line list of \citet{Tafelmeyer2010}, we discarded
the weakest lines which would be overly altered by the noise or
blended. This selection ensures that our sample stars, spanning a large portion
of the RGB, are all analysed in a homogeneous way. Our final line list is
presented in Table \ref{Linelist}. It encompasses 50 \ion{Fe}{I} lines: 20 in
HR10, 21 in HR13, and 9 in HR14. The HR13 and HR14 grisms have a small
overlapping region. The lines in common were considered in the HR13 part only,
taking advantage of its higher resolution.

For each star of photometric $T_\mathrm{eff}$, \ensuremath{\log g}, and v$_{\rm turb}$, we selected the closest
synthetic spectra with these parameters, namely with $T_\mathrm{eff}$\ within 50 K and
\ensuremath{\log g}\ within 0.1 dex. We interpolated them at the value of v$_{\rm turb}$.  The
$\chi^{2}$ values were then calculated for [Fe/H] varying from $-4.0$ to $-0.5$
in steps of 0.1 dex. Finally, the $\chi^{2}$-[Fe/H] relation was interpolated to
a $0.01$~dex step level in order to properly locate the minimum of the relation.  The
corresponding metallicities are given in Table \ref{Stellar_param}.

We note that the maximum differences in $T_\mathrm{eff}$\ and \ensuremath{\log g}\ between the
photometric stellar parameters and the values adopted in the grid are
$25$~K and $0.05$~dex, respectively. These differences are smaller than the
systematic errors on the photometric estimates.

Re-inserting the final value of [Fe/H] into the colour--temperature
formula does not significantly affect the effective temperatures. The
maximum difference $\Delta T_\mathrm{eff}$ with respect to the initial
estimate is $45$~K, which is twice smaller than the systematic errors.
Therefore, we kept the initial effective photometric temperatures.

\subsection{Elemental abundances}

Once [Fe/H] was determined, we derived the abundances of the rest of the
elements using the same chi-squared minimisation procedure as for the
metallicity.  Again, the $\chi^{2}$-[X/H] relation was interpolated to reach a
[X/H] step of 0.01 dex.
Thanks to the wavelength coverage of our spectra we were able to
derive abundances of ten elements: Mg, Ca, Sc, Ti, Cr, Mn, Co, Ni, Ba, and Eu.

We took into account the hyperfine structure for the odd atomic number isotopes :
\ion{Sc}{II} \citep{Prochaska2000}, \ion{Mn}{I} (from Kurucz
database\footnote{available at
  http://kurucz.harvard.edu/linelists.html} as in \citet{North2012}),
\ion{Co}{I} \citep{Prochaska2000}, \ion{Ba}{II} \citep{Prochaska2000}, and
\ion{Eu}{II} (\citet{Lawler2001} as in \citet{VanderSwaelmen2013}).
The complete line list with wavelengths, excitation potentials,
oscillator strengths, and $C_6$ constants is presented in
Table~\ref{Linelist}.  The hyperfine components are indicated in
italics and their corresponding lines are followed by the text
`\textit{(equi)}'.  The abundances are given in Tables
\ref{Abundances_A}, \ref{Abundances_B}`, and \ref{Abundances_C}. The
solar abundances from \citet{GrevesseSauval1998} are repeated in the
first line of these three tables.
Figure \ref{spectra} presents three examples of observed and  synthetic best fits that span
the range of S/N encountered in this study.

\begin{figure*}
\includegraphics[width=\hsize]{Plot_partspec_HR10_revised.pdf}
\caption{Part of the HR10 spectrum of S08-6 (top), S08-242 (middle) and S05-67
  (bottom) in black with their synthetic best fits over-plotted in red.  A set
  of lines used in abundance determination are indicated for each star.  The
  stars are ranked from top to bottom by decreasing signal-to-noise ratios:
  $83$, $38$, and $23$.}
\label{spectra}
\end{figure*}

Figure \ref{spectra} presents three examples of observed and  synthetic best fits that span
the range of S/N encountered in this study.

\subsection{Error budget}
The errors on the abundances derived for the GIRAFFE sample, reported as
error bars in all figures, correspond to the quadratic sum of the systematic
errors and the random errors defined below and indicated in Tables
\ref{Abundances_A}, \ref{Abundances_B}, and \ref{Abundances_C}.

\begin{itemize}
\renewcommand{\labelitemi}{$\bullet$}
\item Systematic errors

Taking as systematic errors a typical variation of $\pm$ 100 K in effective
temperatures, which accurately represents (75\% of our sample) the maximum variation
in $T_\mathrm{eff}$\ from one colour to the other, we re-derived the stellar parameters and
abundances for each star. We obtained small systematic shifts: between $0.04$
and $0.075$ for the  surface gravities, and an average of $0.01$~\kms on
the micro-turbulence velocities.  The systematic errors on [Fe/H] range from $0.1$
to $0.17$~dex, with an increasing trend with decreasing effective
temperature. For the other abundances, the smaller systematic errors are found
for Mg, Sc, Ti, and Eu with $0.05$~dex on average and the larger for Cr and Mn
with $0.2$~dex on average. Examples are provided in Fig.~\ref{Err_FeH_XFe}.

We also considered the effect of the uncertainty on the distance of
Sextans, which is $\sim \pm$ $5$~kpc around our adopted value \citep{Irwin1990,
  Lee2003}.  This translates into an uncertainty of $0.05$~dex on the surface
gravities, and corresponds to the same order of magnitude as
varying the effective temperatures by $\pm$ 100 K.\\

   \begin{figure}[!h]
   \centering
   \includegraphics[width=\hsize]{Pascale_sys_random_err_XH.pdf}
   \caption{Distribution of the systematic and random errors as a function of S/N and effective temperature. These
     examples are shown for the elements for which we have the largest number of detections.
      We refer to the main text for a detailed definition of these errors.}
      \label{Err_FeH_XFe}
   \end{figure}

\item Random errors

Variations in S/Ns may well impact the results
differently depending on the atmospheric parameters and the chemical
enrichment of the stars. Our sample spans more than 1 dex in [Fe/H]
and 1000 K in $T_\mathrm{eff}$.

The random errors on the abundances were therefore estimated from Monte Carlo
simulations. For each star, at given $T_\mathrm{eff}$, \ensuremath{\log g}, v$_{\rm turb}$, and [Fe/H], we generated
1000 spectra with the same S/N as the observed spectrum. The
abundances were then determined on these simulated noisy spectra.
The adopted random error corresponds to the standard deviation of the Gaussian function that best fits the distribution of the  1000 obtained abundances.
Figure \ref{Err_FeH_XFe} presents some example of these randoms errors on [Fe/H] and [X/H]
as a function of S/N.
From one set to the another, the higher the effective temperature and surface gravity, the
larger the impact of the noise, because the lines are smaller.

Based on this exercise, we only considered the abundances of
stars for which we have spectra of S/N $>$ 10  as secure. Indeed, regardless of the reliability of the metallicities, the errors on the other elements can reach $1$~dex,
hampering any reliable interpretation.

\end{itemize}

\section{How well do we perform ?}

The purpose of this section is to assess the quality of our analysis and also to
check that previously published stellar abundances in Sextans can be combined with our work
to provide a robust view of Sextans' chemical evolution.

\subsection{Comparison with the medium-resolution CaT sample}

Calcium triplet metallicity estimates are available for a subset of 32 stars
with S/N $> 10$ \citep{Battaglia2011}. Figure \ref{FeH_CaT_vs_FeH_Synth}
presents a comparison between the [Fe/H] estimates of this latter study and
ours.  The agreement is excellent with a mean difference of $0.0014$~dex and a
standard deviation of $0.137$~dex. This comparison led us to discard from
further analysis two stars with $\Delta$[Fe/H]$> 0.4$ dex common to both
studies: S08-75 and S08-59, identified with triangles in
Fig. \ref{FeH_CaT_vs_FeH_Synth}.  A closer look indeed reveals that the
metallicity of S08-75 is based on only nine iron lines because its spectra have
been polluted by simultaneous calibration fibres in HR10 and HR13.  The position
of S08-59 on the CMD of Sextans sheds doubt on its RGB status; it is most likely
a horizontal branch star.

\begin{figure}
\centering
\includegraphics[width=\hsize]{Comp_FeH_CaT_vs_FeH_Synth.pdf}
\caption{Comparison between the CaT metallicity estimates and the
  [Fe/H] values derived from spectral synthesis (SYNTH). The size of the points
  is a function of the S/N of the spectra.  The two stars
  S08-75 and S08-59, which have been discarded from further analysis
  (see text) are identified with triangles. We highlight in red the
  stars which have been independently analysed with a classical method based on
  equivalent widths and which are in Fig.\ref{FeH_Fit_Eqw}.}
\label{FeH_CaT_vs_FeH_Synth}
\end{figure}

\subsection{Equivalent width versus synthesis}
\label{eqwsynth}

Given that the chemical abundances in the literature are generally derived with
methods based on equivalent widths, but also, and more specific to this work,
because two of our sample stars were gathered with UVES and analysed in this
classical way, it is important to check for the existence of any significant bias
between this type of analysis and the spectral synthesis (`SYNTH').

To this aim, a subsample of 11 bright (V$<$ 19 mag) stars (S08-3, S08-6,
S05-10, S08-38, S08-239, S08-241, S08-242, S07-69, S05-60, S08-246, and S08-183)
from the GIRAFFE sample was independently analysed with \textit{CALRAI}
in the same way as our two UVES stars. We refer to this method as ``EQW'' in the following.  The only difference with the analysis of the UVES
stars is that we fixed $T_\mathrm{eff}$\ to its photometric value. Only the turbulence
velocity v$_{\rm turb}$\ was determined by requesting a null slope (within the fit uncertainties
resulting from the measurement errors) of the relation between the abundances
and equivalent widths of the individual \ion{Fe}{I} lines. The line list and equivalent widths are
provided in Table \ref{tab:eqw}.

Figure \ref{FeH_Fit_Eqw} summarises the comparison between the two methods, EQW
and SYNTH, for the determination of \ion{Fe}{I}. The sizes of the symbols are proportional to the spectrum average S/Ns.  The dashed lines are
placed at $\pm 0.1$ dex of the $x=y$ line. There is a tendency for the EQW
\ion{Fe}{I} abundances to be slightly higher -- by $\sim$0.08 dex on average,
with a standard deviation of 0.09 dex -- than the SYNTH metallicities.

Even if this difference falls well within the error bars, it is interesting to
try and understand its origin.  Different factors can be invoked and they are
sometimes combined: a variety of S/Ns, the use of different
line lists, and different ways of deriving the micro-turbulence velocities
between the two techniques (requesting a null slope comparing \ion{Fe}{I}
abundances and equivalents widths for EQW, while it is estimated from an
empirical relation linked to \ensuremath{\log g}\ for SYNTH).  To illustrate this latter
point, the relation between the differences in [Fe/H] and the variations in v$_{\rm turb}$\
is shown in Fig.~\ref{Delta_FeH_vs_Delta_vturb}: a difference in v$_{\rm turb}$\ of
$0.1$~\kms can result in a $\Delta $[Fe/H] $\geq 0.1$ dex.  The star S05-60
has the largest metallicity difference between EQW and SYNTH. As a
matter of fact, the micro-turbulence velocities differ by $0.3$~\kms between the
two methods.

The case of the star S08-6 illustrates the influence of the linelist. The
difference of $0.1$ dex between the EQW and SYNTH results,
[Fe/H]$_{\rm EQW} = -1.5$ and [Fe/H]$_{\rm SYNTH} = -1.6$, is reduced
  to $0.03$~dex simply by using the exact same \ion{Fe}{I} line
  list. In this case, [Fe/H] $_{\rm SYNTH} = -1.53$ dex.

   \begin{figure}
   \centering
   \includegraphics[width=\hsize]{Comp_Fit_EqW_FeH.pdf}
      \caption{Comparison between the
        metallicity derived from our synthesis code, [Fe/H]$_{\rm SYNTH}$,
      and with a classical method based on the equivalent widths of the individual
      iron lines Fe/H]$_{\rm EQW}$ (see text). The solid line traces the line of
        equality while the dashed lines indicate a variation by $\pm 0.1$ dex. The
        size of the black circles increases with the S/N of the spectra.}
        \label{FeH_Fit_Eqw}
   \end{figure}

\begin{figure}
   \centering
   \includegraphics[width=\hsize]{Delta_FeH_vs_Delta_vturb.pdf}
      \caption{Differences between the metallicities obtained by the
        EQW and SYNTH methods as a function of the differences of the
        stellar micro-turbulence velocities. }
        \label{Delta_FeH_vs_Delta_vturb}
   \end{figure}

Figure \ref{Comp_XH_EQW_SYNTH_all_El} provides a comparison of the
two techniques for three $\alpha$-elements Mg, Ca, and
\ion{Ti}{II}. These are the elements for which we have the largest number of detections, providing
a reliable comparison. Here, again the abundances resulting from the two techniques are
perfectly consistent within the error bars.

\begin{figure}
\centering
\includegraphics[width=\hsize]{Comp_XH_EQW_SYNTH_all_El.pdf}
\caption{Comparison between the abundances of three $\alpha$-elements derived by the EQW  and SYNTH methods. The
solid line traces the line of equality while the dashed lines indicate a
variation by $\pm$ 0.1 dex around this line.}
\label{Comp_XH_EQW_SYNTH_all_El}
\end{figure}

\subsection{Comparison with literature}

\label{comp_giraffe}
S08-3 is the brightest star of the GIRAFFE sample. It has also
been observed with HIRES at the Keck I telescope at a resolution of
R$\sim$34000 and analysed by \citet{Shetrone2001}. There are ten
elements in common between the three independent types of analyses,
SYNTH, EQW in this work, and
\citet{Shetrone2001}. Figure~\ref{S08-3_common} presents a
comparison of the results from these analyses.  The median of the difference between the studies is 0.09
dex with a minimum at 0.01 dex and a maximum at 0.30 dex, all well
within the error bars.

\begin{figure}
   \centering
        \includegraphics[width=\hsize]{S08-3_common_XH_3studies_FORPAPER.pdf}
      \caption{Elemental abundances of the star S08-3. The green circles refer to this study,
      the blue stars come from \cite{Shetrone2001}, and the magenta squares are from the EQW analysis.}\label{S08-3_common}
   \end{figure}

In conclusion, the tests we performed confirm that the choice of one or the
other technique to derive the elemental abundances is a source of only minor variation
in the results, and we did not find any bias or deviation that would exceed the
uncertainties on the abundances. Therefore, we confidently combine our UVES/EQW
and GIRAFFE/SYNTH analyses with previously published results in following
discussion.

\section{Results}

\subsection{Metallicity distribution function}

The metallicity distribution function of our FLAMES sample stars is presented in
Figure \ref{MDF}. The Sextans members (green solid line) are compared to the
DART medium-resolution Ca triplet survey \citep[blue solid
  line;][]{Battaglia2011}. Our distribution peaks around [Fe/H] = $-1.8$ dex and
is almost completely included in the CaT distribution. Keeping only the stars
with CaT metallicity estimates, we obtain the filled green area peaking at the
same [Fe/H] value as the original CaT distribution.  Our full dataset is on
average slightly more metal-rich than the full CaT DART survey. This is most
likely a consequence of the different spatial distribution of the two samples
(see Figure \ref{Star_Location}) and the presence of a radial gradient in
Sextans \citep{Lee2009, Battaglia2011}. Our field is centrally concentrated
(diameter of 25\arcmin), while the DART CaT survey covers FLAMES fields
distributed from the centre to near the tidal radius of Sextans.
\citet{Revaz2018} have shown that gas tend to concentrate in the central regions
of the dwarf spheroidal galaxies which consequently have the longest star
formation activity. Indeed the analysis of the colour-magnitude diagrams
indicates progressively longer timescales of star formation towards the galaxy
centre \citep{Lee2009}. Therefore, our central FLAMES field is probing the full
chemical evolution of Sextans as illustrated by the fact that we cover a very
large metallicity range, from $-3.2$ to $-1.5$~dex.

Among the stars with $S/N \ge 10$ spectra, two are found at [Fe/H] $\le -3:$
S05-94 and S08-257. Two more have [Fe/H] $\sim -2.90$, namely S08-71 and S11-97, which
makes them eligible, within the uncertainties, for membership of the class of extremely
metal-poor stars. Indeed, S11-97 has been reobserved with UVES at a
resolution of $\sim 40 000$ and is confirmed as an EMP (Lucchesi et al., in
prep).

  \begin{figure}
   \centering
   \includegraphics[width=\hsize]{MDF_CaT.pdf}
      \caption{Metallicity distribution function of the Sextans stars. Following the same
      colour code as in Figs. \ref{Star_Location} and \ref{CMD}. The blue solid line
      corresponds to the probable members of the CaT DART sample
      \citep{Battaglia2011}, while the green solid line shows our high-resolution sample. The filled
      green area corresponds to the subsample of our members previously studied in CaT.}
         \label{MDF}
   \end{figure}

\subsection{$\alpha$-elements}
\label{alpha}

Three $\alpha$-elements are accessible in our wavelength range:
\ion{Mg}{I} (1 line), \ion{Ca}{I} (13 lines), and Ti at its two
ionization levels, \ion{Ti}{I} (4 lines) and \ion{Ti}{II} (4
lines). The distribution of [$\alpha$/Fe] as a function of [Fe/H] is
presented in Fig.~\ref{AlphaFe} for Sextans and the Milky Way
stars. Only stars with S/N$>$10 spectra are considered.  Our study
significantly increases the existing samples at high resolution with 46 new
stars in [Mg/Fe], 37 in [Ca/Fe], and 34 in [Ti/Fe].

The comparison samples taken from the literature come from works
conducted at high spectroscopic resolution, at the exception of
\citet{Kirby2010II} with R$\sim$7000. In order to keep the level of
accuracy in abundance ratios as homogeneous as possible between the
different references, we restricted the sample of \citet{Kirby2010II}  to
the eight stars with error on [Fe/H] $\leq 0.12$ dex. The star S15-19 was analysed by both \citet{Aoki2009} and \citet{Honda2011}. We
consider the abundances of the latter study. We refer the reader to
Lucchesi et al. (in prep) for a full reanalysis of the sample of
\citet{Aoki2009}.

\subsubsection{\ion{Ti}{I} versus \ion{Ti}{II}}
Due to the weakness of the \ion{Ti}{I} lines, we were only able to derive the [\ion{Ti}{I}/Fe] abundance
ratio  in four stars (S05-47, S08-3, S08-6, S08-38), while
[\ion{Ti}{II}/Fe] could be calculated in 32 stars. Still, the result on
[\ion{Ti}{I}/Fe] for S05-47 is extremely uncertain as it relies on a single
line.  The three other stars show lower [\ion{Ti}{I}/Fe] than
[\ion{Ti}{II}/Fe] but the estimates  agree within the error bars.
In the following, [Ti/Fe] is taken as  [\ion{Ti}{II}/Fe] similarly to our previous studies.

\begin{figure}
\centering
\includegraphics[width=\hsize]{AlphaFe_R.pdf}
\caption{Distribution of [Mg/Fe], [Ca/Fe], and [Ti/Fe] as a function
  of [Fe/H] for the Sextans dSph (in green).
The circles are the new stars
  from our Giraffe sample; the squares display the re-analysed sample
  of \citet{Shetrone2003}; the stellar symbols stand for the dataset of
  \citet{Aoki2009}, the down-pointing triangles for \citet{Kirby2010II}, the right-pointing
  triangles for \citet{Tafelmeyer2010}, and the diamond from
  \citet{Honda2011}. The Milky Way comparison sample shown in grey encompasses
\citet{Venn2004, Cayrel2004, Francois2007, Gratton2003, Cohen2006, Cohen2008, Cohen2013, Honda2004B, Reddy2006, Yong2013, Lai2007, Spite2005, Aoki2005, Aoki2007, Barklem2005, Ishigaki2013}.}
\label{AlphaFe}
\end{figure}

\subsubsection{Comparison between $\alpha$-elements and impact of the SNeIa}
Figure \ref{AlphaFe} shows the common trend between the three $\alpha$-elements and
[Fe/H]: a plateau at constant [$\alpha/Fe$] with [Fe/H] followed by a
  decrease down to subsolar values.   The scatter in abundance ratios
  scales with the number of lines of each element usable in the analysis and the
  S/N of the spectra. This is particularly true for [Mg/Fe], for which the
scatter at fixed [Fe/H] and the error bars are the largest.  Regarding the stars
  with subsolar [Mg/Fe] values, three are particularly noticeable, S08-282,
  S08-280, and S05-47, in order of increasing [Fe/H], with [Mg/Fe] $< -0.5$.
While the exact Mg abundance for these stars is not yet secure,  as
  uncertainties are large, the comparison with other stars in the sample at
similar atmospheric parameters confirms their low values: S08-282 ($T_\mathrm{eff}$=5044K,
\ensuremath{\log g}=1.96, 1.61, [Fe/H]=$-1.96$) was compared to S05-84 (5048K, 1.92, 1.62,
$-1.96$; [Mg/Fe] = 0.5), and S05-47 (4654K,1.28, 1.74, $-1.64$) to S08-242
(4657K, 1.44, 1.44, $-1.71$; [Mg/Fe] = +0.05).

The trend seen in Fig.~\ref{AlphaFe} is formed by a plateau at
[$\alpha$/Fe]$\sim 0.4$ ended by the so-called knee, which is the [Fe/H] origin
of the decrease in [$\alpha$/Fe] with increasing metallicity, corresponding to
the time when, after a decrease in the galaxy star formation rate, the
contribution of the SNeIa starts to dominate the chemical composition of the
ISM. This new FLAMES sample offers for the first time a large
number of stars with abundances derived at sufficient accuracy to estimate the
location of this knee in Sextans at [Fe/H] $\sim -2$~dex.

The galaxy star formation history shapes the morphology of the [$\alpha$/Fe]
versus [Fe/H] diagram. The similar position of the knee reveals similar star formation
efficiency in the first few gigayears of the galaxy evolution, while the slope of the
decrease in [$\alpha$/Fe] is determined by the balance between the mass of
metals ejected by the SNeIa on the one hand and by the SNeII on the other
hand. Therefore, past the peak of its star formation rate, a system with
extended star formation history will lead to a decrease in [$\alpha$/Fe] versus
[Fe/H] with a smaller slope than a galaxy that is quenched sharply. As a
consequence, it is quite informative to compare the decreasing [$\alpha$/Fe]
branches of the classical dwarfs.

The { position of the knee in the Carina dSph is still  an open issue,
most probably because of the overlap of stellar populations coming from the
three different star formation episodes. It was tentatively detected between
$-2.7$ and $-2.3$~dex \citep{Lemasle2012, Venn2012}, however not confirmed by
\cite{Norris2017}. The spectroscopic samples of other dSphs, such as those of
Draco and Ursa Minor, are still too small to robustly locate their knees
\citep{CohenHuang2009, CohenHuang2010}. The Fornax and Sculptor dSphs, for which
there exists sufficiently large spectroscopic samples, are therefore the two
systems that are comparable to Sextans \citep{Letarte2010, hill2019}.  The
Sextans and Sculptor dSphs have formed stars for 4 to 6 Gyrs, respectively
\citep{Lee2009,deBoer2011}, while the period of star formation in Fornax is more
extended, beyond 12 Gyr even if at a low final rate \citep{deBoer2012b}. Figure
\ref{AlphaKnee} compares the corresponding [$\alpha$/Fe] versus [Fe/H] patterns,
and provides a detailed view of the knee region.  Formally, the position of the
Sextans knee is slightly below those of Sculptor \citep[$\sim
  -1.8$][]{Tolstoy2009}, and Fornax \citep[$\sim -1.9$][]{Hendricks2014a}.  In
practice these values are essentially identical given the uncertainty on both
[Fe/H] and on the exact position of the knee due to the scatter in [$\alpha$/Fe]
at fixed metallicity. This is an impressive agreement given that these galaxies
span a factor of $\sim$50 in final stellar masses and a range of dynamical
status (Sculptor 2.3 $\times$ 10$^6$ M$_{\star}$ ($\sigma$ = 9.2 km/s), Sextans
0.44$\times$ 10$^6$ M$_{\star}$ ($\sigma$ = 7.9 km/s), Fornax 20$\times$ 10$^6$
M$_{\star}$ ($\sigma$ = 11.7 km/s); \cite{McConnachie2012}).  It provides
evidence that, in the first gigayears, the star formation efficiency (the mass
of newly born stars per unit gas mass) of the three galaxies was very
similar. This period of time corresponds to the initial merging sequence of
small galactic units building the galaxy potential well, which will then be
massive enough (or not) to resist the UV-background heating
\citep{Revaz2018}. In other words, up to the knee, the star formation processes
are essentially dominated by the smaller building blocks. The chemical evolution
past the knee then reflects the in-situ star formation when the mass of the
systems is already in place. This part depends on the degree to which the
galaxies have been impacted (quenched) by the UV background.  As expected from
the length of their star formation histories, the slope of the [$\alpha$/Fe]
versus [Fe/H] branches is steeper for Sextans than for Sculptor and Fornax.

\begin{figure}
\centering
\includegraphics[width=\hsize]{AlphaFe_knee.pdf}
\caption{Comparison between the three classical dwarfs, Sextans (green), Sculptor
  (blue), and Fornax (red), and the Milky Way (grey) in the region of the knee in [$\alpha$/Fe].}
\label{AlphaKnee}
\end{figure}

\subsection{Iron-peak elements}

 The number of stars for which the abundances could be determined is smaller
 than for the $\alpha$ elements: 20 stars for Cr, 5 stars for Mn, 2 stars for Co, and
 6 stars for Ni, as a consequence of the weakness of the lines and the large differences in
 the S/Ns of the spectra.

   \begin{figure}

   \includegraphics[width=\hsize]{ScNiCoFe_R.pdf}
      \caption{Abundance ratio for the iron-peak elements Sc, Ni, and Sc for the Sextans dSph in green
in comparison with the Milky-Way population in grey. Symbols are as in Fig.\ref{AlphaFe}.}
      \label{ScNiCoFe}
   \end{figure}

Figure \ref{ScNiCoFe} presents the abundance ratios of Sc, Ni, and Co to Fe.
These have been derived from three lines of \ion{Sc}{II}, 6 lines of \ion{Ni}{I},
and one line of \ion{Co}{I}. The production of Sc is dominated by SNeII
\citep{Woosley2002, Battistini2015}, and therefore, as expected, [Sc/Fe] follows the same
trend with [Fe/H] as the $\alpha$-elements. The case of Ni and Co is different
because these elements can also be largely produced by SNeIa
\citep{Timmes2003,Travaglio2005}. The $\sim 2$ Gyr of star formation history
of Sextans, albeit with a sharp drop in SFR beyond the explosion timescale of
SNeIa, makes it an ideal system to witness their nucleosynthesis imprint.
\cite{Kirby2019} conducted an analysis of the Cr, Ni, and Co abundance
trends in dwarf spheroidals in order to constrain the nature of the SNeIa
progenitors. In particular, they compared the theoretical yields of
  Chandrasekhar-mass SNIa and sub-Chandrasekhar-mass models to existing
  observed abundances in dwarf galaxies. Figure \ref{ScNiCoFe} confirms the
decline of [Co/Fe] and [Ni/Fe] past [Fe/H]$\ge -2$.  This implies that the
production of Ni and Co is lower than the yield of Fe in SNeIa. Our conclusions agree with those of
 \cite{Kirby2019}, in that while the observation of [Co/Fe] is
compatible with most of the models, the decrease in [Ni/Fe]  down to
  subsolar values favours the explosion of double degenerate
sub-Chandrasekhar-mass white dwarfs \citep{Shen2018,Bravo2019}.  This nevertheless
requires conformation with NLTE calculations when they become available.

Figure \ref{CrMnFe} shows the two other iron-peak elements that we were able to
measure, \ion{Cr}{I} (3 lines) and \ion{Mn}{I} (4 lines).  \cite{North2012}
derived the abundance of Mn for the same stars as the present analysis. The results of their study agree with ours within 1$\sigma$ uncertainties. Therefore, for the sake of
homogeneity Fig.~\ref{CrMnFe} displays the results of the synthetic approach of
this work.

Both Cr and Mn closely follow the Milky Way trends. There are no NLTE
calculations available for the range of stellar atmospheric parameters covered
by our sample, either for Cr or for Mn.  Nevertheless,
\citet{BergemannCescutti2010} show that the steady increase of [Cr/Fe]
with metallicity observed for the MW metal-poor stars is an artefact of
neglecting NLTE effects in the line formation of Cr. These NLTE corrections are
positive and move [Cr/Fe] close the solar value over the full range of
metallicities. Given the similar behaviour of the metal-poor population in dwarfs
and the Milky Way, there are good reasons to believe that NLTE is also at the
origin of the low [Cr/Fe] values at [Fe/H] $\le -2$. The fact that [Cr/Fe] is
again solar beyond the position of the knee in Sextans suggests that the
production of chromium is very similar in SNeII and SNeIa.

Departures from LTE have been studied by \cite{Bergemann2008} and
  \cite{Bergemann2019} for slightly hotter stars than our sample and for
different lines from those in our list but in the same metallicity
range. The NLTE abundances of Mn were systematically higher than the
LTE abundances by up to 0.6 dex. This is probably more than needed for
our sample in Sextans to place the sequence of [Mn/Fe] on the solar sequence. if confirmed,
similarly to Cr, the production of Mn should be very similar in SNeII and SNeIa.

   \begin{figure}
   \centering
   \includegraphics[width=\hsize]{CrMnFe_R.pdf}
      \caption{Distribution of [Cr/Fe] (top panel) and [Mn/Fe] (bottom panel) for stars in Sextans and
      the Milky Way. Symbols are as in Fig.~\ref{AlphaFe}.}
         \label{CrMnFe}
   \end{figure}

\subsection{Neutron-capture elements}

We were able to analyse two neutron-capture process elements: \ion{Ba}{II} (2 lines)
measured for 39 stars and \ion{Eu}{II} (1 line) obtained for 7 stars. These
elements are produced in the rapid (r-) and the slow (s-) neutron capture
processes.

   \begin{figure}[!h]
   \centering
   \includegraphics[width=\hsize]{BaEuFe_R_comp.pdf}
      \caption{Distributions of [Ba/Fe] (top panel), [Eu/Fe] (middle panel), and
        [Ba/Eu] (bottom panel)  for stars in Sextans (green), Fornax (red),
          Sculptor (blue), and the Milky Way (grey). The upper limit on Eu of
        \cite{Honda2011} for S15-19 at [Fe/H] $\sim -3$ is indicated with an
        arrow.}
         \label{BaEu}
   \end{figure}

Figure \ref{BaEu} presents the evolution of [Ba/Fe], [Eu/Fe], and [Ba/Eu] as a
function of [Fe/H]. The Sextans stars follow the trend of the MW stars in
[Ba/Fe], with a plateau very slightly above the solar level following the $\sim$
1 dex initial scatter between Fe/H]$\sim -3$ and [Fe/H]$\sim -2.5$. We were only
  able to measure europium for a few stars. These sample the solar plateau in
  barium. There is a small but clear decrease of [Eu/Fe] at [Fe/]$\ge -2$,
  indicating that the production of iron progressively overtakes that of Eu, as
  expected from the decrease in star formation rate and the growing impact of
  the explosions of SNeIa.  There is a slight increasing trend of [Ba/Eu] with
  [Fe/H], inversely reflecting the variation of [Eu/Fe] with [Fe/H], with all
  values [Ba/Eu] below [Fe/H] $\sim -1.5$ being subsolar indicating that below
  [Fe/H]$\sim -2$, barium is produced either entirely or mainly by the
  r-process. The low-metallicity asymptotic giant branch stars (AGBs) are
  sufficiently numerous at Fe/H]$\ge -2$ that [Ba/Eu] increases by the addition
    of the s-process elements. Sextans's chemical evolution does not extend as
    far as that of Sculptor; in particular, there is no star in the $-1.5$ to
    $-1$ [Fe/H] range.  However, between [Fe/H]= $-2.3$ and $-1.5$ the two
    galaxies share the same chemical trends, implying similar fractions of SNeIa
    and low-metallicity AGBs \citep{hill2019}. The comparison with Fornax is
    more difficult due to the lack of measurements of europium. Nevertheless, in
    the same low-metallicity range, Fornax does show the same plateau at
    [Ba/Fe]$\sim$0, confirming the universal timescale of the onset and rise of
    the s-process \citep{Lemasle2014}

\section{Summary and conclusions}

We present an analysis of the FLAMES dataset, targeting the central
25\arcmin\ region of the Sextans dSph. This dataset is the
third  part of the ESO large program 171.B-0588(A) obtained by the
Dwarf galaxy Abundances and Radial-velocities Team (DART) together with the
Fornax and Sculptor galaxies \citep{Letarte2010,hill2019}.  A total of 101
stars have been gathered with the HR10, HR13, and H14 gratings of the multi-fibre
spectrograph FLAMES/GIRAFFE. Two fibres were linked to the red arm of the UVES
spectrograph.

Our sample is composed of RGB stars down to V$\sim$20.5 mag, the
level of the horizontal branch in Sextans. Spectra in the
CaT region are also available for some of them \citep{Battaglia2011}, with first estimates of their
metallicity. The rest of the sample was photometrically selected as
corresponding to the position of Sextans in the $V$,$I$ colour-magnitude
diagram. We provide [Fe/H] determination for 81 stars, which cover the wide
metallicity range [Fe/H]=$-$3.2 to $-$1.5 dex. After a thorough investigation
of the random and systematic errors, we deliver accurate abundances of three
$\alpha$-elements (Mg, Ca and Ti), five iron-peak elements (Sc, Cr, Mn, Co, and Ni),
and two neutron-capture elements (Ba and Eu).
Despite the small stellar mass of Sextans, its stellar population
reveals a  rich chemical evolution involving core collapse and
Type Ia supernovae, as well as low metallicity AGBs.

The analysis of the $\alpha$-elements reveals a plateau at
[$\alpha$/Fe]$\sim$0.4 followed by decrease, corresponding to the time when the
contribution of the SNeIa begins to dominate the chemical composition of the
ISM. This new FLAMES sample offers for the first time a  large
number of stars with abundances derived at sufficient accuracy to estimate the
location of the knee in Sextans at [Fe/H]$\sim -2$ dex, very close
to both the Sculptor and Fornax dSphs, despite their
very different masses and star formation histories. This provides evidence that,
in the first gigayears, the star formation of the three galaxies followed similar
processes, such as the accretion of smaller building-blocks before the period
of reionisation.

[Sc/Fe] follows the same trend with [Fe/H] as the $\alpha$-elements,
confirming that its production is dominated by SNeII. Ni and Co can be
produced by SNeII and SNeIa.  We confirm the decline of [Co/Fe] and
[Ni/Fe] past [Fe/H]$\ge -2$, implying that the production of Ni and
Co in SNeIa is lower than that of Fe.  While the observation of
[Co/Fe] is compatible with most of the models of SNeIa, the decrease
in [Ni/Fe] favours the explosion of double degenerate
sub-Chandrasekhar-mass white dwarfs. The fact that [Cr/Fe] is solar
and [Mn/Fe] is flat beyond the position of the knee in Sextans
suggests that the production of chromium and manganese is very similar
in SNeII and SNeIa.

The stellar population of Sextans follows the same trend as the Milky Way stars
in [Ba/Fe], with a plateau at solar level following the initial scatter below
[Fe/H]$\sim -3$. The trend of [Ba/Eu] with [Fe/H] indicates that below [Fe/H]
$\sim -2$, barium is produced either entirely or at least principally by the rapid neutron
capture channel. The low- metallicity AGBs are sufficiently numerous at Fe/H]
  $\sim -2$  that [Ba/Eu] increases by the addition of the s-process elements. In the
  metallicity region covered by the three galaxies, Sculptor, Fornax, and Sextans
  share the same trends, suggesting similar fractions of SNeIa and low-metallicity
  AGBs in their early evolution.

\begin{acknowledgements} The authors are indebted to the International Space Science Institute (ISSI),
Bern, Switzerland, for supporting and funding the international teams "First
stars in dwarf galaxies" and "Pristine''.  RT, PJ, PN, and CL also thank the Swiss
National Science Foundation for its support.
\end{acknowledgements}

\bibliographystyle{aa}

redpajama_set_name: RedPajamaArXiv


text:
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This set of Lesson Plans consists of approximately 113 pages of tests, essay questions, lessons, and other teaching materials.
Name: _________________________ Period: ___________________
This test consists of 15 multiple choice questions and 5 short answer questions.
1. What did Elias notice about the man in the field when he was following him afterward?
(a) His enery was drained.
(b) He was himself.
(c) He was pretending.
(d) He was a friend.
2. Where was Julian's family from, according to the telling of his story by Don Juan?
(a) Mexico City.
(b) Baja.
(c) Nogales.
(d) Iquitos.
3. Where does Elias serve as a sorcerer who interacts with people, according to the book?
(a) Peru.
(b) Columbia.
(c) Northern Mexico.
(d) Southern Mexico.
4. What is the name of Don Juan's teacher from whom Don Juan has learned how to become a sorcerer?
(a) Julian.
(b) Don Matus.
(c) Elias.
(d) Ricardo.
5. Understanding the __________ means moving beyond the comprehensible, according to the teaching of Don Juan, but Carlos is confused.
(a) Commitment.
(b) Truth.
(c) Passion.
(d) Abstract cores.
6. How many eyes does the mysterious figure have, the one that Don Juan can see, though no one else can?
(a) Three.
(b) None.
(c) Two.
(d) One.
7. ___________ is the procedure by which a person can directly connect with the powers of intent and with the shift in perception.
(a) Dreaming.
(b) Apprenticeship.
(c) Sleep.
(d) Sorcerey.
8. What is the illness which overtook Julian and caused him to shift not only his perspective, but also his direction in life?
(a) Cancer.
(b) He didn't have an illness.
(c) Tuberculosis.
(d) Pneumonia.
9. ___________ can be described and can be represented, according to Don Juan, but intent can not.
(a) Nature.
(b) God.
(c) Spirit.
(d) Earth.
10. Belisario says that in order for Don Juan to escape, he needs to follow him to _____________ and become a sorcerer.
(a) Phoenix.
(b) Mexico City.
(c) Durango.
(d) Nogales.
11. ________ protected Don Juan from the harsh onslaughts of thought that were coming from Julian.
(a) Don Matus.
(b) Elias.
(c) Carlos.
(d) No one.
12. Carlos and Don Juan leaves his home in order to go to ________ where they begin to discuss the moods of stalking.
(a) Iquitos.
(c) Sonora.
13. What happened to Julian when he met the woman the next day in the field in order to become intimate with her?
(a) She died.
(b) She began hitting him.
(c) He began to hit her.
(d) He died.
14. What does Julian join before he has his powerful experience with spirit knocking on his door?
(a) Medicine man.
(b) Acting troupe.
(c) Ritual circle.
(d) Apprenticeship.
15. This abstract core involves learning to stalk oneself or dusting off the ______ with intent, according to the writing.
(a) Intention.
(b) Permission.
(c) Link.
(d) Alignment.
1. Elias was _________ to a city when he came upon a well-dressed man in a field, who was seducing a woman.
2. Who had saved Julian by dreaming him, by seeing him, and by stalking him, according to the story in this book?
3. Where does Julian end up which is where his life ends and the spirit knocks on his door?
4. Don Juan says that ________ was an excellent dreamer and stalker, according to his own opinions and memories.
5. There is an unmeasurable, indescribable force that sorcerers call _________, according to the book.
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