Science/AAAS | Science Magazine : Previous Issues

La datation U-Th (Uranium-Thorium) des croûtes carbonatées révèle l’origine néandertalienne de l’art pariétal ibérique.

▻http://science.sciencemag.org/content/359/6378/912.full

http://img.lemde.fr/2018/02/22/0/0/750/525/534/0/60/0/625fffa_8483-15hmc1e.khap.JPG https://d2ufo47lrtsv5s.cloudfront.net/content/sci/359/6378/912/F1.medium.gif

L’étendue et la nature du comportement symbolique chez les Néandertaliens sont obscures. Bien que des preuves de l’ornementation du corps de Néandertal aient été proposées, toutes les peintures rupestres ont été attribuées aux humains modernes. Ici, nous présentons les résultats de datation pour trois sites en Espagne qui montrent que l’art rupestre a émergé en Ibérie sensiblement plus tôt que prévu. Les datations uranium-thorium (U-Th) sur des croûtes carbonatées recouvrent des âges minimums pour un motif linéaire rouge à La Pasiega (Cantabrie), un pochoir à main à Maltravieso (Estrémadure) et des spéléothèmes peints en rouge à Ardales (Andalousie). Collectivement, ces résultats montrent que l’art pariétal en Ibérie est âgé de plus de 64,8 mille ans (ka). Cet art rupestre est le plus ancien daté à ce jour et précède d’au moins 20 ka l’arrivée des humains modernes en Europe, ce qui implique la paternité de l’homme de Neandertal.

L’étude détaillée :
▻http://www.sciencemag.org/content/359/6378/912/suppl/DC1

La réaction de certains préhistoriens qui souhaitent vraiment voir « la tête » de certains de leurs confrères opposés à ce que Néandertal soit capable de symbolisme , ici :
▻http://science.sciencemag.org/content/359/6378/852.full

Et plus, sérieusement, quelques doutes sur les possibles erreurs de datations car l’uranium aurait pu être lessivé #Ludovic_Slimak #cnrs #Michel_Fontugne #Laboratoire_des_sciences_du_climat_et_de_l'environnement
▻http://www.lemonde.fr/sciences/article/2018/02/22/neandertal-est-il-le-premier-auteur-de-peintures-rupestres_5261139_1650684.h

#Préhistoire #art_pariétal #Néandertal # Université_de_Southampton #D_L_Hoffmann #Paul_Pettitt #Université_de_Durham #J_Zilhão #Université_de_Barcelone #64000bp

Un pas de plus vers la reconnaissance de l’#anthropocène comme nouvelle ère géologique avec ce papier dans Science de l’Anthropocene Working Group.

The Anthropocene is functionally and stratigraphically distinct from the Holocene
▻http://www.sciencemag.org/content/351/6269/aad2622.full

The appearance of manufactured materials in sediments, including aluminum, plastics, and concrete, coincides with global spikes in fallout radionuclides and particulates from fossil fuel combustion. Carbon, nitrogen, and phosphorus cycles have been substantially modified over the past century. Rates of sea-level rise and the extent of human perturbation of the climate system exceed Late Holocene changes. Biotic changes include species invasions worldwide and accelerating rates of extinction. These combined signals render the Anthropocene stratigraphically distinct from the Holocene and earlier epochs.

’Case is made’ for Anthropogenic Epoch
▻http://www.bbc.com/news/science-environment-35259194

“Within the Working Group - and we have 37 members - I think the majority of them now agree that we are living in an interval we should call the Anthropocene. There’s still some discussion as to whether it should be a formal or informal unit, but we’d like to have a specific definition. And a majority of the group are moving towards the mid-20th Century for the start of this new epoch.”

[...]

Ultimately it will be down to the International Commission on Stratigraphy to accept - or not - the “Anthropocene Epoch” as an additional unit in the official time scheme used to describe the planet’s 4.6 billion years of history.

Lotka-Volterra c’est fini
▻http://www.sciencemag.org/content/349/6252/aac6284

Across ecosystems globally, pyramid structure becomes consistently more bottom-heavy, and per capita production declines with increasing biomass. These two ecosystem-level patterns both follow power laws with near ¾ exponents and are shown to be robust to different methods and assumptions.

#recherche #écologie #écosystèmes #proie-prédateur #loi_de_puissance

(une version plus digeste (?) ici ▻https://www.washingtonpost.com/news/energy-environment/wp/2015/09/03/researchers-may-have-just-stumbled-upon-a-mathematical-secret-to-how)

Estimating the reproducibility of psychological science
▻http://www.sciencemag.org/content/349/6251/aac4716

http://www.sciencemag.org/content/349/6251/aac4716/F1.small.gif

One of the central goals in any scientific endeavor is to understand causality. Experiments that seek to demonstrate a cause/effect relation most often manipulate the postulated causal factor. Aarts et al. describe the replication of 100 experiments reported in papers published in 2008 in three high-ranking psychology journals. Assessing whether the replication and the original experiment yielded the same result according to several criteria, they find that about one-third to one-half of the original findings were also observed in the replication study.

#Réplication #SHS

Sea Levels Could Rise At Least 20 Feet | Climate Central
▻http://www.climatecentral.org/news/sea-levels-rise-20-feet-19211

Even if world manages to limit global warming to 2°C — the target number for current climate negotiations — sea levels may still rise at least 6 meters (20 feet) above their current heights, radically reshaping the world’s coastline and affecting millions in the process.

That finding comes from a new paper published on Thursday in Science that shows how high sea levels rose the last time carbon dioxide levels were this high.
[…]
“Even if we meet that 2°C target, in the past with those types of temperatures, we may be committing ourselves to this level of sea level rise in the long term,” Andrea Dutton, a geochemist at the University of Florida and one of the study’s co-authors, said. “The decisions we make now about where we want to be in 2100 commit us on a pathway where we can’t go back. Once these ice sheets start to melt, the changes become irreversible.”

L’article (du moins le résumé, le reste derrière #paywall)
Sea-level rise due to polar ice-sheet mass loss during past warm periods
▻http://www.sciencemag.org/content/349/6244/aaa4019

OUTLOOK
Our present climate is warming to a level associated with significant polar ice-sheet loss in the past, but a number of challenges remain to further constrain ice-sheet sensitivity to climate change using paleo–sea level records. Improving our understanding of rates of GMSL rise due to polar ice-mass loss is perhaps the most societally relevant information the paleorecord can provide, yet robust estimates of rates of GMSL rise associated with polar ice-sheet retreat and/or collapse remain a weakness in existing sea-level reconstructions. Improving existing magnitudes, rates, and sources of GMSL rise will require a better (global) distribution of sea-level reconstructions with high temporal resolution and precise elevations and should include sites close to present and former ice sheets. Translating such sea-level data into a robust GMSL signal demands integration with geophysical models, which in turn can be tested through improved spatial and temporal sampling of coastal records.

Further development is needed to refine estimates of past sea level from geochemical proxies. In particular, paired oxygen isotope and Mg/Ca data are currently unable to provide confident, quantitative estimates of peak sea level during these past warm periods. In some GMSL reconstructions, polar ice-sheet retreat is inferred from the total GMSL budget, but identifying the specific ice-sheet sources is currently hindered by limited field evidence at high latitudes. Given the paucity of such data, emerging geochemical and geophysical techniques show promise for identifying the sectors of the ice sheets that were most vulnerable to collapse in the past and perhaps will be again in the future.

http://www.sciencemag.org/content/349/6244/aaa4019/F1.large.jpg

Quelques canulars mémorables, pour la science - Arrêt sur images
▻http://www.arretsurimages.net/articles/2015-06-02/Quelques-canulars-memorables-pour-la-science-id7770

L’objectif déclaré de Bohannon : s’attaquer à la « pseudo-science » constituée par certaines études sur les régimes alimentaires, et à ses canaux de diffusion. Le journaliste-biologiste n’en est pas à son coup d’essai en matière de vraies-fausses études. En octobre 2013, il avait révélé comment il était parvenu à faire accepter la publication d’un faux article sur une méthode de lutte contre le cancer à 157 journaux (sur 304 sollicités).

Rédigés en mauvais anglais, truffés d’erreurs et signés de pseudonymes générés automatiquement, les articles portaient sur une molécule présente dans le lichen, censée inhiber la croissance de cellules tumorales. John Bohannon ne les a pas soumis à n’importe quelles revues : il a ciblé les journaux scientifiques en libre-accès (en ligne). Ces derniers, nés en réponse au monopole des grands éditeurs scientifiques, sont l’objet d’un débat : côté pile, ils permettent à des lecteurs qui ne sauraient s’offrir les coûteux abonnement aux grandes revues (parfois plus de 4000 euros par an) d’avoir accès à des travaux de recherche, mais côté face, le système attire son lot d’entrepreneurs peu scrupuleux, qui font payer d’importantes sommes d’argent à de jeunes chercheurs en mal de publications, sans assurer de relecture par un comité de pairs. C’est sur ce second aspect que le canular de Bohannon a mis le doigt de façon spectaculaire.

En plus d’un article (un vrai, cette fois), Bohannon a exposé son forfait dans une savoureuse carte interactive :

liste des journaux selon l’outcome :
▻http://www.sciencemag.org/content/342/6154/60/suppl/DC1
papier :
►http://www.sciencemag.org/content/342/6154/60.full

Facebook Said Its Algorithms Do Help Form Echo Chambers. And the Tech Press Missed It. | Zeynep Tufekci via @antoniocasilli
▻http://www.huffingtonpost.com/zeynep-tufekci/facebook-algorithm-echo-chambers_b_7259916.html

http://i.huffpost.com/gen/2938642/images/o-ZEYNEP-TUFEKCI-FB-facebook.jpg

Four of nine planetary boundaries now crossed
▻http://www.pierrejoris.com/blog/?p=12737

http://www.pierrejoris.com/blog/wp-content/uploads/2015/01/PB_FIG33_globaia_dotted-e1421415509437.jpg

Four of nine planetary boundaries have now been crossed as a result of human activity, says an international team of 18 researchers in the journal Science. The four are: climate change, loss of biosphere integrity, land-system change, altered biogeochemical cycles. The scientists say that two of these, climate change and biosphere integrity, are “core boundaries” – significantly altering either of these would “drive the Earth System into a new state”. The team will present their findings in seven seminars at the World Economic Forum in Davos (21-25 January).

L’article de Science (le résumé, le reste derrière #paywall)

Planetary boundaries : Guiding human development on a changing planet
▻http://www.sciencemag.org/content/early/2015/01/14/science.1259855

The planetary boundaries framework defines a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth System. Here, we revise and update the planetary boundaries framework, with a focus on the underpinning biophysical science, based on targeted input from expert research communities and on more general scientific advances over the past 5 years. Several of the boundaries now have a two-tier approach, reflecting the importance of cross-scale interactions and the regional-level heterogeneity of the processes that underpin the boundaries. Two core boundaries—climate change and biosphere integrity—have been identified, each of which has the potential on its own to drive the Earth System into a new state should they be substantially and persistently transgressed.

Genomes reveal start of Ebola outbreak

▻http://www.sciencemag.org/content/345/6200/989.full

When the young woman arrived at the Kenema Government Hospital in Sierra Leone in late May, she had high fever and had just miscarried. The hospital suspected she had contracted Lassa fever, because the viral disease is endemic in the region and often causes miscarriages. But Ebola virus disease, another hemorrhagic fever illness, had been spreading in neighboring Guinea for months, so when she began bleeding profusely, staff tested her for that virus as well. The results were positive, making her the first confirmed case of Ebola in Sierra Leone.

The young woman, who eventually recovered, is now at the heart of a tragic but potentially important research tale. In a paper online this week in Science, a collaboration led by Stephen Gire and Pardis Sabeti of Harvard University and the Broad Institute in Cambridge, Massachusetts, report sequencing and analyzing the genomes of Ebola virus samples from 78 people in Sierra Leone who were diagnosed with Ebola between late May and mid-June, including the young woman who came to Kenema’s hospital. The 99 complete sequences—some patients were sampled more than once—provide insights into how the virus is changing during the outbreak, which could help improve current diagnostic tests and, in the long term, guide researchers working on vaccines and treatments.

#ebola

World population stabilization unlikely this century
▻http://www.sciencemag.org/content/early/2014/09/17/science.1257469

Analysis of these data reveals that, contrary to previous literature, world population is unlikely to stop growing this century. There is an 80% probability that world population, now 7.2 billion, will increase to between 9.6 and 12.3 billion in 2100

au lieu des prévisions précédentes à 9 milliards (désolé je n’ai pas accès au texte complet)
#population

Study: Left alone with their thoughts, people choose electric shock
▻http://www.latimes.com/science/sciencenow/la-sci-sn-people-alone-thoughts-mind-dislike-electric-shocks-20140703-story

“But what is striking is that simply being alone with their own thoughts for 15 minutes was apparently so aversive that it drove many participants to self-administer an electric shock that they had earlier said they would pay to avoid."

Just think: The challenges of the disengaged mind
▻http://www.sciencemag.org/content/345/6192/75.abstract
#concentration #solitude

Genomic surveillance elucidates #Ebola #virus origin and #transmission during the 2014 outbreak
▻http://www.sciencemag.org/content/early/2014/08/27/science.1259657.full

This West African variant likely diverged from Middle African lineages ~2004, crossed from Guinea to Sierra Leone in May 2014, and has exhibited sustained human-to-human transmission subsequently, with no evidence of additional zoonotic sources. Since many of the #mutations alter protein sequences and other biologically meaningful targets, they should be monitored for impact on diagnostics, vaccines, and therapies critical to outbreak response.

Ebola virus mutating rapidly as it spreads
▻http://www.nature.com/news/ebola-virus-mutating-rapidly-as-it-spreads-1.15777

Further comparisons suggest that the virus that caused the outbreak separated from those that caused past Ebola outbreaks about 10 years ago. It had accumulated more than 395 mutations between that time and June, when the researchers collected the last samples included in today’s analysis.

The virus amassed 50 mutations during its first month, the researchers found. They say there is no sign that any of these mutations have contributed to the unprecedented size of the outbreak by changing the characteristics of the Ebola virus — for instance, its ability to spread from person to person or to kill infected patients. But others are eager to examine these questions.

And such risks rise as the virus continues to spread. “The longer we allow the outbreak to continue, the greater the opportunity the virus has to mutate, and it’s possible that it will mutate into a form that would be an even greater threat than it is right now,” says Charles Chiu, an infectious-disease physician at the University of California, San Francisco.

Cinq coauteurs d’une étude sur Ebola ont été tués par le virus avant sa publication
par Jean-Yves Nau,
le 28 août 2014
►http://m.slate.fr/story/91505/cinq-coauteurs-etude-ebola-tues-virus

C’est une publication sans précédent qui vient d’être mise en ligne sur le site de la revue américaine Science. Une double première. D’abord, parce qu’elle met en lumière la dynamique génétique intime des innombrables isolats du virus Ebola qui progressent actuellement en Afrique de l’Ouest. Ensuite, parce que cinq de ses signataires sont morts avant de voir leurs noms publiés dans la prestigieuse revue de l’American Association for Advancement of Sciences.

Cinq morts sur cinquante-huit auteurs, cinq morts infectés par le virus contre lequel ils luttaient. L’article avait été adressé pour publication à la rédaction en chef de Science le 5 août. Après relectures par des pairs, il a été accepté le 21 août et est donc publié sept jours plus tard. Quatre auteurs sont morts avant sa rédaction finale, le cinquième pendant la relecture.

Les cinquante-trois auteurs toujours vivants rendent hommage à leurs collègues en fin de publication :
« In memoriam : de manière tragique, cinq des coauteurs, qui ont grandement contribué au maintien de la santé publique et à l’effort de recherche en Sierra Leone, ont contracté le virus Ebola durant leur travail et ont été vaincus par la maladie avant la publication de cette étude. Nous voulons honorer leur mémoire. »

Ils avaient pour noms Mohamed Fullah, Mbalu Fonnie, Alex Moigboi, Alice Kovoma et Humarr Khan. Tous travaillaient à l’hôpital gouvernemental de Kenema, en Sierra Leone. (...)

Ce travail a été mené sur 99 isolats de virus Ebola obtenus après des prélèvements de sang effectués chez 78 malades de Sierra Leone. Après une série d’analyses génomiques particulièrement sophistiquées effectuées en un temps record, la communauté scientifique internationale dispose, pour la première fois depuis la découverte du virus en 1976, de données sur les mécanismes de reproduction et de mutation du virus.

Les chercheurs confirment pour la première fois avec des preuves moléculaires l’hypothèse avancée par des chercheurs français selon laquelle le virus Ebola qui sévissait jusqu’alors en Afrique centrale a divergé pour donner celui qui frappe aujourd’hui l’Afrique de l’Ouest –sans doute véhicule par des #chauves-souris frugivores porteuses saines. Ils confirment également qu’un seul type de virus est à l’origine de l’épidémie actuelle, qui a émergé fin 2013 en Guinée.

Report : Dogs Eating Dead Bodies Of Ebola Victims On Liberian Streets
▻http://atlanta.cbslocal.com/2014/08/27/report-dogs-eating-dead-bodies-of-ebola-victims-on-liberian-street

The New Dawn reports that the Liberian government buried bodies of those suspected to have died from Ebola a few weeks ago in Johnsonville Township, outside of Monrovia. A number of dogs were reportedly seen pulling the bodies out of the graves and eating the remains.

Des courants marins empêchent la hausse des températures à la surface du globe (étude) - Techniques de l’Ingénieur
▻http://www.techniques-ingenieur.fr/actualite/environnement-thematique_191/des-courants-marins-empechent-la-hausse-des-temperatures-a-la-s
▻http://www.techniques-ingenieur.fr/actualite/environnement-thematique_191/des-courants-marins-empechent-la-hausse-des-temperatures-a-la-surface-du-globe-etude-article_287542/figures/media_287542_media2/courant10.jpg

An Infographic That Maps 2,000 Years of Cultural History in 5 Minutes | Design | WIRED

▻http://www.wired.com/2014/08/an-infographic-that-maps-2600-years-of-cultural-history-in-5-minutes

Fascinant. On se demande quoi faire en cartographie après avoir vu ça...

▻https://www.youtube.com/watch?v=4gIhRkCcD4U

Ah, Hollywood. Our glowing beacon of modern hope and dreams. But before Hollywood, there was New York, and before New York there was Berlin, Paris, Rome and Greece. History’s most creative people have always flocked to cultural and intellectual hubs, and now, thanks to an amazing visualization from researchers at the University of Texas at Dallas, we can see how that migration has changed over time.

http://www.wired.com/wp-content/uploads/2014/08/cultural-migration-trends.gif

Last week in the journal Science, the researchers (led by University of Texas at Dallas art historian Maximilian Schich) published a study that looked at the cultural history of Europe and North America by mapping the birth and deaths of more than 150,000 notable figures—including everyone from Leonardo Da Vinci to Ernest Hemingway. That data was turned into an amazing animated infographic that looks strikingly similar to the illustrated flight paths you find in the back of your inflight magazine. Blue dots indicate a birth, red ones means death.

#cartographie #visualisation #culture #cartographie_animée

Plus d’humains, moins d’invertébrés
▻http://www.lapresse.ca/actualites/sciences/201407/24/01-4786524-plus-dhumains-moins-dinvertebres.php

Face au quasi-doublement du nombre d’êtres humains sur la Terre depuis 40 ans, le nombre d’#insectes, de vers et de crustacés a baissé de 45%, estiment des chercheurs dans une étude parue jeudi dans la revue Science.

Les invertébrés —tous les #animaux qui ne possèdent pas de colonne vertébrale— sont des êtres indispensables à la Terre : ils pollinisent les cultures, réduisent les insectes nuisibles, filtrent l’eau et nourrissent le sol de nutriments.

Les chercheurs estiment que 322 espèces de vertébrés ont disparu dans les cinq derniers siècles. Les espèces restantes comptent en outre 25% d’individus en moins.

« Nous avons été très surpris de découvrir que les pertes chez les invertébrés étaient similaires à celles d’animaux plus grands, car nous pensions jusqu’à présent que les invertébrés étaient plus résistants », a expliqué Ben Collen, de l’University College London, coauteur de l’étude.

Deux facteurs contribuent à la disparition des invertébrés, selon les chercheurs : la perte d’habitat et le #changement_climatique.

Une autre étude publiée dans le même numéro de Science décrit un rapport de cause à effet entre la disparition d’espèces animales et l’augmentation des #conflits, du crime organisé et de l’exploitation des enfants à l’échelle mondiale.

La destruction d’emplois et la pénurie alimentaire pourraient provoquer directement une hausse du trafic d’êtres humains, selon cette étude menée par des chercheurs de l’Université de Californie à Berkeley.

« Cet article décrit le déclin de la faune comme une source, et non un symptôme, de conflits sociaux », explique l’auteur principal, le professeur Justin Brashares.

« Des milliards de gens dépendent directement et indirectement des ressources sauvages de viande pour leurs revenus et leur subsistance, et cette ressource diminue », dit-il.

À titre d’exemples, le chercheur relève que les activités de piraterie au large de la Somalie ont pour origine un conflit sur les droits de pêche.

Les deux papiers :
Defaunation in the #Anthropocene
▻http://www.sciencemag.org/content/345/6195/401
Wildlife decline and social conflict
▻http://www.sciencemag.org/content/345/6195/376

#biodiversité

We can’t count on plants to slow down global warming
▻http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/may/09/cant-count-on-plants-slowing-global-warming

The authors note that many experiments have shown the increased CO2 usually helps stimulate photosynthesis and plant growth. Some of this extra CO2 ends up in the soils where it is unable to participate as a greenhouse gas.

The current authors went a step further though. They asked what happens to the carbon after it is in the soils. We know that microbes decompose soil matter and thereby release the carbon back to the air. Will this process increase, decrease, or stay the same as the climate warms and climate change progresses? It is important because soil stocks (the amount of carbon contained in soil) is determined by a balance between the influx and outflux of carbon.

The authors found that increased CO2 in the atmosphere actually increased the outflux of carbon dioxide from the soils. That is, it increased the rate of decomposition. In the long run, the increases in influx and outflux will essentially balance out. This suggests that there will be little help from the biosphere for us humans – plants will not take up our emissions.

The authors have two competing hypotheses behind the physical mechanisms that drive the decomposition. They told me that it is possible the plants close their stomata (the tiny pores which allow water and CO2 to pass into and out of leaves). As the stomata close, the soils become wetter and microbial activity increases. The authors also think that as atmospheric CO2 increases, soil microbes respond by decomposing older soil carbon. They call this a “priming effect” which is a natural buffering mechanism that slows carbon accumulation in soils.

Author Dr. Bruce Hungate from the Center for Ecosystem Science and Society told me,

“ These results add to an increasingly clear picture that natural carbon sinks are finite. In particular, the soil carbon sink driven by rising CO2 concentrations has probably been overestimated. Natural land ecosystems are unlikely to sequester as much carbon as we had hoped. We should not expect nature to mop up the atmosphere for us. We have long thought soils to be a stable, safe place to store carbon, but our results show that soil carbon is not as stable as we previously thought .”

This all goes to show that it is really up to us humans, the emitters of greenhouse gases to take the lead on fixing the problem we started. The earlier we take action, the easier it will be.

▻http://www.sciencemag.org/content/344/6183/508.abstract

#climat #carbone #plantes

La #soundscape_ecology, ou étudier un écosystème par le son.

Eavesdropping on Ecosystems
▻http://www.sciencemag.org/content/343/6173/834.full

Sueur and his colleagues weren’t interested in exactly which species were calling. Instead, he says they wanted “to take a global measure of the acoustic output of the community.” Their goal was an algorithm that could boil hours of acoustic data down to a single number describing how an ecosystem’s acoustic energy is distributed across the frequency spectrum and over time.

[...]

The boom in sound-recording studies poses a challenge familiar in other fields: a glut of data. Pijanowsky’s lab alone has amassed about 85 terabytes of sound—more than 100,000 hours—in just 5 years. “This is a science that’s plagued by the big data challenges that you see in, say, genetics,” he says. Many researchers already have libraries of field recordings that, if played in real time, would be longer than their careers. “We know that we’re not going to be able to listen to it all,” says computer scientist Michael Towsey of the Queensland University of Technology in Brisbane, Australia.

To get around that problem, he’s developing ways to navigate soundscapes by sight, creating color-coded spectrograms that trained eyes can interpret at a glance. Towsey describes the visualizations as “#acoustic_weather” charts. Some show how the spectrum of sounds shifts over a single day, while others assemble daily records into long-term snapshots to capture changes between seasons or years. That’s akin to studying the “#acoustic_climate,” he notes. And “when we start thinking about the acoustic climate, then we can start thinking about acoustic climate change.” Year-to-year comparisons could eventually highlight subtle and potentially problematic changes, he predicts, such as changing rain patterns or shifts in bird activity.

http://www.sciencemag.org/content/343/6173/834/F6.large.jpg

Computer scientist Michael Towsey combines 8 months of continuous recordings at a research station in Brisbane, Australia, into a single image. Colors indicate different acoustic indices. At dawn (left curve), a morning bird chorus (blue) is obvious during the Australian spring and early summer (October through December), but fades later in the year. Horizontal green streaks indicate heavy rainfall in January and February. At dusk (right curve), cicada activity is evident in the spring and summer months (green); by winter, the night is increasingly silent.

#ecologie #sons #field_recording #biodiversite #eco-acoustique

« A riderless bicycle can automatically steer itself so as to recover from falls. The common view is that this self-steering is caused by gyroscopic precession of the front wheel, or by the wheel contact trailing like a caster behind the steer axis. We show that neither effect is necessary for self-stability. »

Résumé : la science ne sait toujours pas pourquoi les bicyclettes ne tombent pas.

▻http://www.sciencemag.org/content/332/6027/339

#physique #vélo

La #forêt amazonienne inventoriée pour la première fois
▻http://lemonde.fr/planete/article/2013/10/17/la-foret-amazonienne-inventoriee-pour-la-premiere-fois_3497885_3244.html

Difficile de se figurer ce que représente l’Amazonie, plus vaste aire de forêt tropicale humide et plus grand réservoir de biodiversité au monde, qui s’étend sur près de 6 millions de km2 et sur neuf pays. Pour la première fois, une équipe internationale de chercheurs a dressé l’inventaire des arbres qui peuplent ce bassin, afin d’en connaître la diversité, la rareté et la richesse, dans une étude publiée dans la revue Science, vendredi 18 octobre.

Il en résulte que la forêt amazonienne est composée de près de 390 milliards d’arbres appartenant à environ 16 000 espèces différentes. Parmi elles, 227 (soit 1,4 % du total) sont hyper dominantes et totalisent plus de la moitié des individus, alors que les 11 000 essences rares décomptées représentent seulement 0,12 % des spécimens.

▻http://www.sciencemag.org/content/342/6156/1243092

« On a cartographié chaque parcelle, étudié le sol, mesuré la hauteur et la circonférence de chaque arbre et prélevé des échantillons de bois pour les analyser en laboratoire », décrit Daniel Sabatier, chercheur spécialiste de la forêt amazonienne à l’Institut de recherche pour le développement, qui a participé à l’étude. Les données ont été regroupées dans le réseau international Amazon Tree Diversity Network. Une extrapolation – grâce à un modèle de distribution des abondances – a finalement permis d’obtenir des statistiques sur l’ensemble du bassin.

▻http://testweb.science.uu.nl/Amazon/atdn

http://s2.lemde.fr/image/2013/10/17/534x0/3497992_5_e306_les-1-170-parcelles-de-1-hectare-examinees-par_0a02cd24ce4fd9a9be63924f481e8065.jpg

Who’s Afraid of Peer Review ? — John Bohannon (Science)
►http://www.sciencemag.org/content/342/6154/60.full

est-ce facile de publier dans des journaux scientifiques ? Un chercheur fabrique des articles faux (de façon flagrante), les envoie à 400 journaux, et regarde qui accepte de les publier (moyennant finances).

Journals published by Elsevier, Wolters Kluwer, and Sage all accepted my bogus paper. (...) The Elsevier journal that accepted the paper, Drug Invention Today, is not actually owned by Elsevier, says Tom Reller, vice president for Elsevier global corporate relations: “We publish it for someone else.”

#publication #open_access #recherche #spam #flagrant_délit