Optical physics: Supercavity lasing
Nature 541, 7636 (2017). doi:10.1038/541164a
Authors: Mikhail Rybin & Yuri Kivshar
Light in a laser is confined in the form of standing waves. By engineering such waves, scientists have designed an optical system that enhances this confinement, producing a compact laser that emits a high-quality beam. See Letter p.196
Nature Physics 13, 10 (2017). doi:10.1038/nphys3929
Authors: C. J. Olson Reichhardt & C. Reichhardt
Simple models have given us surprising insight into how animals flock, but most assume they do so through a homogeneous landscape. Colloidal experiments now suggest that a little disorder can have unexpected — and spectacular — effects.
Author(s): Mirjam Weilenmann, Lea Kraemer, Philippe Faist, and Renato Renner
Two notions of entropy are connected using a method reliant on basic properties common to both systems.
[Phys. Rev. Lett. 117, 260601] Published Thu Dec 22, 2016
Author(s): Hridesh Kedia, David Foster, Mark R. Dennis, and William T. M. Irvine
A prediction of divergence-free knotted vector fields from complex scalar fields has consequences for studies of magnetic fields in complex patterns.
[Phys. Rev. Lett. 117, 274501] Published Thu Dec 29, 2016
A map of chaos emerging in a Bose-Einstein condensate provides a rare glimpse of the behavior in a system of many quantum particles.
[Physics] Published Thu Jan 12, 2017
Thanks for all the amazing BAHFest proposals, Londonites! We'll have our selections done shortly, and then tickets will be on sale!
Allora, vediamo se ho capito bene. Il Capo politico, ma sarebbe meglio dire “il proprietario”, del Movimento per la Democrazia Diretta™ indice una elezione online per far confermare la propria decisione di tirare fuori il Movimento dall’EFDD, il Gruppo più euroscettico del Parlamento Europeo, e farlo aderire all’ALDE, il Gruppo più filoeuropeista di tutti, che da sempre professa idee opposte a quelle dell’EFDD. Il Movimento scopre infatti di non avere più lavoro da fare insieme all’EFDD e quindi di andare verso altri lidi. Ok.
La decisione di indire l’elezione viene presa dal Capo e pochi altri senza interpellare i parlamentari del Movimento, che nel 2014 sono stati eletti da 5.800.000 cittadini italiani perché li rappresentassero al Parlamento Europeo. Ma questi elettori e i loro eletti non contano. Nel Movimento per la Democrazia Diretta™ infatti prevale la votazione convocata dal Capo, su un quesito deciso dal Capo stesso, cui votano circa 41.000 persone, cioè circa lo 0,7 % dei quasi sei milioni di elettori del 2014. Il 78% di questi 41.000 fortunati decide di dire “SI” al Capo (chi l’avrebbe mai detto?). Il Movimento quindi decide di aderire all’ALDE in un mirabile tripudio della Democrazia Diretta™.
Sennonché c’è un piccolo intoppo. E cioè che l’ALDE, che non segue i Principi della Democrazia Diretta™ ma funziona secondo i biechi principi della democrazia rappresentativa, non ha un Capo: ha un presidente. Viene fuori che il presidente aveva raggiunto l’intesa col Capo del Movimento per il passaggio all’ALDE, senza decidere sul punto assieme agli altri parlamentari del proprio Gruppo. Molti parlamentari dell’ALDE a questo punto, capendo che i propri elettori sarebbero stati molto scontenti di ricevere il Movimento nel proprio Gruppo, fanno quello che sono pagati per fare e cioè rappresentano i propri elettori opponendosi alla entrata del Movimento, nonostante il loro presidente, non Capo, avesse già una intesa con il Capo del Movimento. Cioè fanno sentire la propria voce per rappresentare i propri elettori anche se questo avrebbe probabilmente scontentato i vertici del proprio Gruppo. Maledetti anarchici!
A questo punto il Movimento per la Democrazia Diretta™ rischia di rimanere senza Gruppo e quindi di perdere peso e finanziamenti all’interno del Parlamento Europeo. A quel punto cosa fa? Essendo il Movimento per la Democrazia Diretta™ uno si aspetterebbe una nuova votazione sul sito del Movimento. Invece no: il Capo fa una telefonata con il presidente della EFDD e si mette d’accordo per ritornare in quel Gruppo, nonostante ne fosse uscito per conflitti non sanabili due giorni prima.
Non è dato capire se gli europarlamentari siano stati consultati sul punto o se invece vengano mossi dentro o fuori dai Gruppi come in una specie di transumanza politica. Il 78% dei votanti sul sito, invece, che il giorno prima aveva deciso di andare nell’ALDE adesso si ritrova nuovamente nel Gruppo più lontano esistente dalla stessa ALDE.
Insomma, mi sa che se la Democrazia Diretta™ è questa io mi tengo la mia antiquata democrazia rappresentativa.
Santé
100 Illustrators that all Illustrators should know: #59
Frank Frazetta (1928-2010)
Country: USA
Famous for: Conan the Barbarian, John Carter of Mars, Tarzan, Sword and Sorcery, Fantasy and Science-Fiction illustration, Comics, Paperback Novel covers, LP covers
Influenced: William Stout, Dave Stevens, Jeff Jones, Bernie Wrightson, Michael Kaluta, Barry Windsor-Smith, Capcom, Nintendo, John Buscema, Mark Schultz, Ken Kelly, Boris Vallejo, Justin Sweet, Brad Rigney, Richard Corben, Mike Mignola, Roy Krenkel, Angelo Torres, Al Williamson, Shane Glines, John Kricfalusi, Arthur Suydam, Paul Bonner, Simon Bisley, Claire Wendling, Bruce Timm, Frank Miller, Frank Cho, Adam Hughes, Steven Spielberg, George Lucas, Robert Rodriguez, Guillermo Del Toro, Alan Lee, John Howe, the Hildebrandt Brothers, Joe Jusko, Marc Silvestri, Michael Whelan, Fantasy, Sci-Fi and Comic art (and the genres themselves) as a whole, Illustration as a whole
Influenced by: Howard Pyle, Gustave Doré, Franklin Booth, Willy Pogany, Zedenek Burian, Wally Wood, Roy Krenkel, Angelo Torres, Al Williamson, J. Allen St. John, Norman Lindsey, Heinrich Kley, N.C. Wyeth, Hal Foster, Frederic Remington
Born Frazzetta (he would later remove one ‘Z’) in 1928 in Brooklyn, Frank Frazetta was a renowned American illustrator of Science Fiction, Fantasy and comics. Encouraged in his art-making from an early age by his grandmother, Frank was what many may consider a child prodigy, and attended the Brooklyn Academy of Fine Arts at the young age of 8; a place Frazetta says he learned more from his friends there as opposed to his professor, Michel Falanga. Frazetta broke into the comics industry at age 16, inking interior pages of humor and gag comics in the mid and early 40s, later working in genres such as western, fantasy, mystery and horror. By the early 1950s, Frank started working for EC comics, among other publications, often collaborating with friends and mentors such as Roy Krenkel and Al Williamson. In 1964, Frazetta would create one of his breakout illustrations; a caricature of Beatles member, Ringo Starr for an ad in Mad Magazine. This illustration caught the eye of United Artists, and was approached for several movie posters during this time. However, his most iconic paintings were done for another big market of the time; Paperback novel covers. In the 60s, 70s and 80s, Frazetta painted a slew of masterpiece covers for stories such as Conan the Barbarian, John Carter of Mars and Tarzan, the likes of which revitalized the entire fantasy genre of illustration and storytelling. During this time, he’d also contribute to Warren’s publications such as Eerie, Creepy, Blazing Combat and Vampirella. Some of his iconic pieces, The Death Dealer, Dark Kingdom, and The Brain were repurposed for album covers in the late 70s for bands such as Molly Hatchet and Nazareth. In the early 80s, Frazetta also collaborated with experimental and underground animator Ralph Bakshi for an animated feature called Fire and Ice. Frazetta was inducted into the Will Eisner Comic Book Hall of Fame in 1995, the Jack Kirby Hall of Fame in 1999, The Society of Illustrators Hall of Fame in 1998, and was named Spectrum Fantastic Art’s first Grand Master in 1995.
Besides Rockwell, Frazetta is among the most prolific and iconic illustrators to ever live and is perhaps the most widely cited specific artist influence in the entire illustration and comic industry. He reinvented the entire fantasy art scene and became an inspiration for newcomers to break into the field and has left an unmistakable mark on pop culture as a whole as a result, influencing properties such as Star Wars to the Legend of Zelda and everything in between. Frazetta passed away at the age of 82 at his home in Florida and his works have been since purchased by collectors or reside in the Frazetta Museum in East Stroudsburg, PA, of which I highly recommend a visit.
Heya guys, not my own art (obviously) but I’ve resumed those ‘100 illustrators every illustrator must know’ posts again, check ‘em out!
Hey guys! Been doing posts on 100 influential illustrators, and finally had my chance to do a long write-up on Frazetta! Check ‘em out!
Ogni paese si costruisce una serie di miti e leggende per poter definirsi tale. Questi miti (oggi le chiamerebbero post-truth) servono a tenere coeso il paese soprattutto nei momenti di difficoltà. Serve anche per dare al cittadino quel senso di superiorità rispetto agli altri popoli per poter andare avanti ogni mattina e mentire a se stessi con il solito mantra tribale: si nasce sempre nel posto migliore, con la lingua più bella, il cibo più buono ecc. Il Regno Unito non fa eccezione e credo di aver individuato i tre più grandi miti che reggono il paese. Se questi miti venissero sfatati o discussi il Regno Unito crollerebbe su se stesso. Ciò ovviamente è impossibile perché queste sono bufale ataviche, imparate cioè fin dall’infanzia, come nell’imprinting di Konradiana memoria.
Una nazione non è fatta solo di tre miti, certo, ma questi tre elencati qui sopra sicuramente contribuiscono alla maggior parte della mentalita’ collettiva britannica e contribuiscono enormemente a molte delle scelte che i governi fanno. Inclusa la Brexit.
The echo of “You can do whatever you want” still rang in my ears.This is something that he learnt from his father and I consider is one of the three biggest lies that Western high school students are taught and need to recnounce as undergraduates.
Robert McNamara was the brightest of a group of ten military analysts who worked together in Air Force Statistical Control during World War II and who were hired en masse by Henry Ford II in 1946. They became a strategic planning unit within Ford, initially dubbed the Quiz Kids because of their seemingly endless questions and youth, but eventually renamed the Whiz Kids, thanks in no small part to the efforts of McNamara.
There were ‘four McNamara steps to changing the thinking of any organisation’: state an objective, work out how to get there, apply costings, and systematically monitor progress against the plan. In the 1960s, appointed by J.F. Kennedy as Secretary of Defense after just a week as Chair of Ford, McNamara created another Strategic Planning Unit in the Department of Defense, also called the Whiz Kids, with a similar ethos of formal analysis. McNamara spelled out his approach to defence strategy: ‘We first determine what our foreign policy is to be, formulate a military strategy to carry out that policy, then build the military forces to conduct that strategy.’
Obsessed with the ‘formal and the analytical’ to select and order data, McNamara and his team famously developed a statistical strategy for winning the Vietnam War. ‘In essence, McNamara had taken the management concepts from his experiences at the Ford Motor Company, where he worked in a variety of positions for 15 years, eventually becoming president in 1960, and applied them to his management of the Department of Defense.’
But the gap between the ideal and the reality was stark. Colin Powell describes his experience on the ground in Vietnam in his biography:
Secretary McNamara...made a visit to South Vietnam. Every quantitative measurement, he concluded, after forty-eight hours there, shows that we are winning the war. Measure it and it has meaning. Measure it and it is real. Yet, nothing I had witnessed . . . indicated we were beating the Viet Cong. Beating them? Most of the time we could not even find them.
McNamara’s slide-rule commandos had devised precise indices to measure the immeasurable. This conspiracy of illusion would reach full flower in the years ahead, as we added to the secure-hamlet nonsense, the search-and-sweep nonsense, the body-count nonsense, all of which we knew was nonsense, even as we did it.
McNamara then used the same principles to transform the World Bank’s systems and operations. Sonja Amadae, a historian of rational choice theory, suggests that, ‘over time . . . the objective, cost-benefit strategy of policy formation would become the universal status quo in development economics—a position it still holds today.’ Towards the end of his life, McNamara himself started to acknowledge that, ‘Amid all the objective-setting and evaluating, the careful counting and the cost-benefit analysis, stood ordinary human beings [who] behaved unpredictably.’Ben Ramalingam, Aid on the Edge of Chaos, Oxford University Press, 2013. pp. 45-46.
Come si fa a dimostrare che ³√2 è irrazionale? Semplice. Supponiamo che ³√2 = a/b. Elevando al cubo, abbiamo a³ = 2b³ = b³ + b³, il che è impossibile per l’Ultimo Teorema di Fermat. (l’umorismo dei matematici è sempre
The post Come dimostrare che la radice cubica di 2 è irrazionale [Pillole] appeared first on Il Post.
Jacopo.bertolottiThis sort of explain how I landed a permanent position at a Physics department :-)
Jacopo.bertolottiCome fosse Antani.
The cute-as-a-jingle phrase “a chicken is a Dirac limit of a tyrannosaur” emerges in the final section of a study called “Diagonalizing the genome II: toward possible applications,” by Satyan L. Devadoss and Jack Morava.
A chicken.
Here’s the full passage in which that phrase crops up:
“Branching in descent diagrams can be modeled by specialization in the sense of algebraic geometry, defined (for example) by fixing some parameter. In the language of stratified spaces this corresponds to moving from the interior of some region to its boundary: something like a phase change (like water to ice). In such a cartoon description, a chicken is a Dirac limit of a tyrannosaur, in which many of its genetic parameters tend to zero. At this level of vagueness, there is reason to work with codimension than with probability: evolutionary events are highly unlikely, and in reasonable models will have effective probability zero; but in geometry any subspace of positive codimension has measure, and hence probability, zero. The modern theory of phase change in condensed matter physics has developed powerful tools for the study of such transitions (viewed as moving towards a stratum boundary, eg of some phenotype), but in current work there is usually only one such event in focus at a given moment. Evolution forces us to consider long concatenations of such events, and trees are a natural tool for their book-keeping.”
(Thanks to Mason Porter for bringing this to our attention.)
BONUS (distantly related, as most things are): “Pretty Good Gravity, by Jack Morava.
L’altro giorno pensavo alla recente (ri)polarizzazione tra Est e Ovest in Europa e mi sono reso conto che a guardar bene la mappa di questa divisione politica e culturale è rimasta inalterata per gli ultimi 2000 anni. Quello che vediamo oggi, la contrapposizione tra Occidente filoatlantista per fare un esempio geopolitico e Oriente filorusso, ha le radici in decisioni politiche prese quasi 2000 anni prima.
Ma andiamo con ordine: c’è stato un solo momento nella storia umana in cui Europa Occidentale e Orientale sono state unite politicamente e culturalmente e questo fu durante la massima espansione dell’Impero Romano. Pensiamo agli imperi di Adriano e Traiano. Costantino sposta la capitale da Roma a Costantinopoli. Nel frattempo il cristianesimo, o meglio una corrente del cristianesimo, viene dichiarato religione di Stato. Da questo momento in poi la storia d’Europa è inestricabilmente legata alla religione cristiana. La divisione però avviene quando una parte dell’Impero crolla sotto le invasioni dei barbari. In quella parte dell’Impero vi era uno dei cinque patriarchi, quello di Roma (gli altri erano a Costantinopoli, Antiochia, Alessandria e Gerusalemme) che si è trovato improvvisamente senza controparte politica (l’ultimo imperatore d’Occidente fu deposto nel 476). Chi occupa il vuoto sono le tribù germaniche prima e poi i Franchi più tardi. Il Patriarca di Roma allora non può fare altro che usare questi nuovi attori per sopravvivere. Nel frattempo con l’invasione araba e la caduta dell’Esarcato d’Africa i patriarcati di Alessandria, Antiochia e Gerusalemme perdono il loro potere di rappresentanza. Alla fine dei giochi chi rimane sono solo due patriarchi, quello di Roma e quello di Costantinopoli. La divisione geografica e politica non fa che enfatizzare quella culturale e religiosa: da una parte latinofoni e barbari, dall’altra grecofoni e romani. L’Europa occidentale è stata quasi completamente germanizzata mentre quella orientale è ancora legata ai valori dell’impero romano ma per poco perché gli arabi premono da sud. Quindi avvenne naturalmente in questo contesto lo scisma del 1054. Il patriarcato di Roma ha raggiunto talmente tanto potere grazie all’alleanza con i franchi che si può permettere di lasciare la Chiesa Cattolica Romana. Lo so, sembra incredibile pensarla in questo modo perché in Occidente abbiamo avuto il lavaggio del cervello su questa cosa per secoli, ma fu Roma la chiesa eretica e scissionista, non il contrario. Gli ortodossi infatti considerano se stessi, ed a ragione, come gli unici depositari della tradizione della Chiesa Cattolica Romana. La Chiesa Cattolica Occidentale ha preso una strada diversa nel corso dei secoli associandosi ai franchi e creando il papismo, ovvero la supremazia del potere religioso su quello secolare. Fino al 1453 invece nell’Impero Bizantino abbiamo il cesaropapismo, ovvero l’imperatore è a capo della chiesa e dell’impero allo stesso tempo.
La cosa interessante è che se non fosse stato per la conquista araba dell’Esarcato d’Africa e dell’Asia Minore non avremmo avuto una cosi marcata polarizzazione tra i due maggiori patriarcati. Comunque sia andata nel 1054 c’è lo scisma e di fatto la cultura occidentale si divide non solo politicamente ma anche religiosamente in due. L’Oriente rimane attaccato alle proprie tradizioni, ortodosso infatti, e non cambia quasi per niente fino ai nostri giorni. Infatti i riti religiosi rimangono quasi invariati e il cesaropapismo rimane un caposaldo dell’equilibrio politico orientale fino ai giorni nostri.
Infatti nel frattempo la Chiesa Ortodossa si espande a Nord prima con i bulgari poi con le popolazioni che formeranno il nucleo delle culture slave odierne. Costantinopoli si sposta culturalmente a nord spinta dai turchi che nel 1453 la invadono per sempre. Mosca diventa la seconda Costantinopoli o come si dice la Terza Roma. In effetti non hanno tutti i torti: c’è un filo conduttore che porta da Roma a Mosca. I russi sono, a ragione, gli ultimi depositari di due dei tratti più salienti della tradizione romana: l’ortodossia e il cesaropapismo. Lo tsar non è altro che l’impersonificazione dell’imperatore bizantino e, a parte la parentesi sovietica, si ritrova di nuovo con Putin. E non è un caso che l’influenza russa in medioriente rifletta ancora questo: gli alleati russi sono storicamente stati l’Egitto, la Siria, l’Armenia ovvero tutti paesi dove le comunità cristiano ortodosse sono ancora rilevanti.
Il potere politico occidentale invece ha avuto una storia policentrica travagliata spostando il suo centro in varie capitali europee fino ad arrivare oltreoceano a Washington che a ragione dovrebbe essere considerata come l’erede dell’Impero Romano d’Occidente. Ed eccoci alla Guerra Fredda, che altro non è se non la riproposizione dello scontro tra Franchi e Bisanzio e frutto dello scisma del 1054. L’Italia si trova al confine in questa guerra dei due mondi, sempre divisa tra i due blocchi: lo era nel 700 d.c. come lo era nel 1945. L’Impero d’Oriente ha sempre avuto un piede sul territorio italiano nonostante si trovi nel blocco occidentale. Lo abbiamo visto durante la Guerra Fredda ma lo vediamo pure oggi con i tanti filoputiniani del Bel Paese.
In un certo senso Russia e Nato non possono rifuggire da questo loro ruolo impostogli dalla storia. Sono tutti attori di un teatrino i cui fili sono retti dalla storia, ovvero da decisioni prese migliaia di anni prima e su cui non hanno alcun controllo.
A fundamental manifestation of wave scattering in a disordered medium is the highly complex intensity pattern the waves acquire due to multi-path interference. Here we show that these intensity variations can be entirely suppressed by adding disorder-specific gain and loss components to the medium. The resulting constant-intensity (CI) waves in such non-Hermitian scattering landscapes are free of any backscattering and feature perfect transmission through the disorder. An experimental demonstration of these unique wave states is envisioned based on spatially modulated pump beams that can flexibly control the gain and loss components in an active medium.
Moving particles with no memory can group together in complex flock configurations using only instantaneous cues.
[Physics] Published Thu Dec 08, 2016
“Our experience of explaining polarimetry to the general public is that they frequently ask how molecules rotate light, which is difficult to explain using non-technical language. Therefore we were keen to find an analogous large scale system which mimicked the polarimeter and used everyday left- and right-handed objects.”
– explain Claire Saxon, Scott Brindley, Nic Jervis, Graeme R. Jones, E. David Morgan, and Christopher A. Ramsden of the School of Chemistry and Physics, Lennard-Jones Laboratories, Keele University, UK. Between them, they have developed the world’s first “Pastarimeter” – inspired by an idea from the late Nobel Laureate Sir Robert Robinson, OM PRS FRSE, whom, whilst working at the University of Sydney in 1914, had shown that short lengths of left- or right-handed screw threads packed into a tube would rotate a stream of water flowing down the tube – perhaps in some ways analogous to the way that chiral molecules rotate light.
“We are now pleased to report that we have succeeded in repeating this experiment and confirming Robinson’s observations. The major stumbling block in the past has been the availability of a left- and right-handed threaded material with a suitably deep thread. We have now found a remarkably cheap and disposable source in our local supermarket in the form of pasta fusilli. Surprising as it may seem, these are available from various retailers in both left- and right-handed forms.”
• See: The World’s First “Pastarimeter”: An Analogous Demonstration of Polarimetry Using Pasta Fusilli J. Chem. Educ., 2002, 79 (10), p 1214.
• Note: Their paper notes an interesting example of how identical molecules – identical that is except for the direction in which they twist – can have wildly differing properties. They cite the case of carvone – a molecule which tastes of spearmint when it twists in one direction and caraway in the other.
• Assignment [optional]: Which other types of pasta exhibit chirality? [references here]
• Also see: Pasta’s place in the history of superconductivity
• Also don’t miss: ‘A taste for anelloni’ from the University of Warwick, UK (using Möbius pasta to illustrate the mysteries of ring-shaped polymers).
• And finally [chirality-in-the-news related] : Help find Jeremy the ‘lefty’ snail a mate , BBC News, Oct. 2016
Still want more pasta analogies? . . .
See Nuclear Pasta (a type of degenerate matter found within the crusts of neutron stars) at Wikipedia :
“When the gnocchi phase is compressed, as would be expected in deeper layers of the crust, the electric repulsion of the protons in the gnocchi is not fully sufficient to support the existence of the individual spheres, and they are crushed into long rods, which, depending on their length, can contain many thousands of nucleons. Immersed in a neutron liquid, these rods are known as the spaghetti phase. Further compression causes the spaghetti phase rods to fuse, and form sheets of nuclear matter. This is called the lasagna phase.”
Jacopo.bertolottiIt's time you and I have "the talk"!
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Drawn with great humility and thanks to one of my favorite people. Scott did all of the real work, and I threw in some dirty jokes. So, hey, a pretty good deal all around.
Also,
Wednesday Book Reviews!
Our Magnificent Bastard Tongue (McWhorter)
I’m still on this McWhorter kick. This one was good, but not as good as some of the others. It’s about English and its interactions with other languages. The bulk of the book is about the idea that repeated conquests of English speakers resulted in English being particularly simplified in terms of its grammar, especially compared to related languages. There is also a large section on a proposed link between Celtic and English grammar, and even a section positing links between German and Hebrew. The latter idea is based on the work of Theo Vennemann, whose ideas are (as far as I could tell from google and wikipedia) found to be interesting but probably wrong. Because it’s McWhorter, there’s also a long lament about the popular usage of the Sapir-Whorf hypothesis. You get the feeling that his later book “The Language Hoax” was a great unburdening of linguistic angst.
An Extraordinary Time (Levinson)
<a href="https://www.amazon.com/gp/product/0062645358/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0062645358&linkCode=as2&tag=ss00a2-20&linkId=2c7c808d43f64
The transmission of a wave through a randomly chosen `pile of plates' typically decreases exponentially with the number of plates, a phenomenon closely related to Anderson localisation. In apparent contradiction we construct disordered planar permittivity profiles which are complex-valued (i.e. have reactive and dissipative properties) that appear to vary randomly with position, yet are one-way reflectionless for all angles of incidence and exhibit a transmission coefficient of unity. We contrast these complex-valued 'random' planar permittivity profiles with a family of real-valued, two-way reflectionless and perfectly transmitting disordered permittivity profiles that function only for a single angle of incidence and frequency.
Questo articolo vi arriva gratuitamente e senza pubblicità grazie alle donazioni dei lettori. Se vi piace, potete farne una anche voi (o fare un microabbonamento) per incoraggiarmi a scrivere ancora. Ultimo aggiornamento: 2016/12/09 7:20.Addio a John Glenn, primo americano nello spazio, pilota di guerra, senatore, candidato alla Casa Bianca, eroe del Right Stuff 1921-2016 pic.twitter.com/v3SjvOtQtr— Gianni Riotta (@riotta) December 8, 2016
@GenChuckYeager 1/2 Sir, a prominent Italian journalist (@riotta) argues that John Glenn was 1st US astronaut and Shepard/Grissom's flights— Paolo Attivissimo (@disinformatico) December 9, 2016
@GenChuckYeager 2/2 don't count as space flights because they were suborbital. They passed the Karman line.Could you weigh in on the matter?— Paolo Attivissimo (@disinformatico) December 9, 2016
@disinformatico @HomerHickam 1959:FAI agreed space was 50 miles 4 security:each country owned that air space.I've seen curvature of earth.— Chuck Yeager (@GenChuckYeager) December 9, 2016
Shepard fece volo suborbitale, orbita lambiva atmosfera. Glenn primo US orbita solo spazio. Poi fate voi ragazzi come vi piace e Buon Natale— Gianni Riotta (@riotta) December 8, 2016
John Glenn lifted the hopes of a nation when he orbited the Earth, and his contributions will forever be remembered: https://t.co/l3neUbeuA3 pic.twitter.com/HIWOudvCjn— NASA (@NASA) December 8, 2016
Holographic free-electron light source
Nature Communications, Published online: 2 December 2016; doi:10.1038/ncomms13705
Controlling the generation of light in nano-scale systems is a challenging task and is of growing importance. Here, Li et al. propose a means of controlling the wavefront of light emanating from a single nano scale emitter by holographic principles using a plasmonic metasurface.
Jacopo.bertolottiSo sad and so true :-(
Doron Zeilberger cast a wary glance at the social gathering habits of his fellow mathematicians. He wrote a little, gleeful diatribe about it:
Opinion 104: The Shocking State of Contemporary “Mathematics”, and the Meta-Shocking Fact that Very Few People Are Shocked
I just came back from attending the 1052nd AMS (sectional) meeting at Penn State, last weekend, and realized that the Kingdom of Mathematics is dead. Instead we have a disjoint union ofnarrow specialties, and people who know everything about nothing, and nothing about anything (except their very narrow acre). Not only do they know nothing besides their narrow expertise, they don’t care!
The “meeting” was not really a meeting. It was many mini-meetings! 22 of them, running in parallel and in complete oblivion of each other. All that they shared was the coffee, tea, and donuts. That’s a little reassuring that an algebraic combinatorialist has at least one thing in common with an algebraic geometer, a q-serieser, and a Heat-kernel group theorist: they all drink coffee (or tea), and eat donuts! But that’s about it….
Each speaker had a special session associated with his narrow specialty, so naturally between 20 to 30 people for each talk were a captive audience. It would be really in bad taste to play hookey on the talk of the organizer of your special session….
You can’t really blame the audience for not showing up, since they were probably burnt out from countless previous invited talks where they didn’t understand a word, or from reading the very technical abstracts of the current talks. Most speakers have no clue how to give a general talk. They start out, very nicely, with ancient history, and motivation, for the first five minutes, but then they start racing into technical lingo that I doubt even the experts can fully follow.
Please! Expand these first five minutes into fifty minutes, tell us about the history, background, motivation, and you don’t have to even mention your own results.
BONUS (possibly related): Claire Kamp Dush’s “How Structural Equation Modeling is Ruining Family Research”
