## on [not] making tea

Posted in Travel with tags , , , , , , , , , , , , on November 14, 2021 by xi'an

By chance, when looking for information on the film that usually appears on top of tea brews (!), I came upon this highly ranked blog entry of a security expert explaining how not to make tea. Which did not seem completely right in my tea-oholic eyes..! Not that the following rambling is of any relevance whatsoever!

On the agreement side, it is indeed hard to get decent tea in most places, the primary reason being a lack of understanding that very hot water is needed. The worst being these cafés where they bring you a cup of (definitely not hot) water with a tea bag on the side! I used to travel with my own kettle to avoid this issue, but I am striving to carry as little stuff as possible and hence gave up on that habit. Instead, I often take a thermos bottle that contains an infuser: all that is needed is hot water!

On the disagreement side, the obvious resolution of most complaints about poor quality tea, “herbal teas” that are not tea, tea bags in general, &tc., is to carry your own loose tea. It is light and keeps well and cannot disappoint. And can be brewed several times, especially oolongs. The section about milk is beyond discussion as tea with milk is another beverage altogether. I certainly enjoy drinking duh-wali-chai  in India and am even making some at home from time to time, but otherwise I stopped putting milk in my tea during the first COVID lockdown. (Which also considerably simplified my tea consumption when travelling: all that is needed is hot water!) The main issue is however in using boiling water. Which is almost never recommended for brewing tea! Especially green and Darjeeling teas. Instead of using water above 90⁰, one should stay below 90⁰… Especially when running several brews. Not only this keeps the bitterness under control but it avoids loosing oxygen and CO² contained in the water.

As an aside, this film/sheen is the result of “an interfacial reaction of polyphenols and other components in the tea that bond with ions in the water”.

## back to W

Posted in pictures, Statistics, Travel, University life with tags , , , , , , , , , , , , on October 3, 2021 by xi'an

## significant changepoint? [poor statistics]

Posted in pictures, Statistics, Travel with tags , , , , , , , on May 5, 2021 by xi'an

A rather short-shighted item of news in Libération on road deaths rising in March 2021 for the first time since the beginning of lockdown in March 2020. The increase is by 22 persons, which is arguably not statistically significant (although terribly significant for the victims and their families) and somehow to be expected when considering the figures are averages over 12 months, hence representing the new volume of driving induced by the lockdown measures like work-at-home, closed schools, cancelled winter vacations. At best the following figures should see a plateau. More globally, this huge dip in the number of deaths, bringing us back to the 1920’s figures!,  is to be celebrated, alas with no prospect that this lower rate will resist a return to higher levels of activity.

## récits du vieux royaume [book review]

Posted in Books, pictures with tags , , , , , , on April 18, 2021 by xi'an

Following my enthusiastic reading of Jaworski’s Gagner la Guerre at the start of the first lockdown last year (!), I read this March the short stories at the beginning of a single volume called Récits du Vieux Royaume, which I found even better for the care in the writing style, the originality and diversity of the stories, the strong connection with traditional folklore and with the woes and worries of rural people, some of which could have been those of my not-so-remote ancestors, the mostly subtle insertion of details on the . (The connection with role game scenarios is close to invisible here.) It is only when reaching the second half of this book that I realised it contained the book I had bought and read last year. Rather than additional jewels…

“Elle racontait des histoires anciennes, des chroniques séculaires, des légendes à demi oubliées, ensevelies dans un passé fabuleux. Elle racontait la Geste de Leodegar le Resplendissant, ses batailles, ses victoires, l’union des clans autour du jeune héros habité par le souffle d’un dieu. Elle racontait le Vieux Royaume à l’époque de sa splendeur, Chrysophée aux murailles dorées, la prospérité et l’harmonie des campagnes, les forteresses orgueilleuses des trois duchés. Aux heures froides de la nuit elle racontait parfois les heures terribles de la guerre des Grands Vassaux, les morts marchant mêlés aux vivants dans les armées de Malvern, Chrysophée incendiée dans le soir, les derniers héros de Leomance, de Kahad Burg et de Valanael, ivres d’horreur et de désespoir, livrant combat pour défendre la berge de la Listrelle..”

## hands-on probability 101

Posted in Books, Kids, pictures, Statistics, University life with tags , , , , , , , , , on April 3, 2021 by xi'an

When solving a rather simple probability question on X validated, namely the joint uniformity of the pair

$(X,Y)=(A-B+\mathbb I_{A

when A,B,C are iid U(0,1), I chose a rather pedestrian way and derived the joint distribution of (A-B,C-B), which turns to be made of 8 components over the (-1,1)² domain. And to conclude at the uniformity of the above, I added a hand-made picture to explain why the coverage by (X,Y) of any (red) square within (0,1)² was uniform by virtue of the symmetry between the coverage by (A-B,C-B) of four copies of the (red) square, using color tabs that were sitting on my desk..! It did not seem to convince the originator of the question, who kept answering with more questions—or worse an ever-changing question, reproduced in real time on math.stackexchange!, revealing there that said originator was tutoring an undergrad student!—but this was a light moment in a dreary final day before a new lockdown.