Entangled single-wire NiTi material: a porous metal with tunable superelastic and shape memory properties

NiTi porous materials with unprecedented superelasticity and shape memory were manufactured by self-entangling, compacting and heat treating NiTi wires. The versatile processing route used here allows to produce entanglements of either superelastic or ferroelastic wires with tunable mesostructures. Three dimensional (3D) X-ray microtomography shows that the entanglement mesostructure is homogeneous and isotropic. The thermomechanical compressive behavior of the entanglements was studied using optical measurements of the local strain field. At all relative densities investigated here ($\sim$ 25 - 40$\%$), entanglements with superelastic wires exhibit remarkable macroscale superelasticity, even after compressions up to 25$\%$, large damping capacity, discrete memory effect and weak strain-rate and temperature dependencies. Entanglements with ferroelastic wires resemble standard elastoplastic fibrous systems with pronounced residual strain after unloading. However, a full recovery is obtained by heating the samples, demonstrating a large shape memory effect at least up to 16% strain.Comment: 31 pages, 10 figures, submitted to Acta Materiali

Molecular evolutionary rates are not correlated with temperature and latitude in Squamata: an exception to the metabolic theory of ecology?

The metabolic theory of ecology stipulates that molecular evolutionary rates should correlate with temperature and latitude in ectothermic organisms. Previous studies have shown that most groups of vertebrates, such as amphibians, turtles and even endothermic mammals, have higher molecular evolutionary rates in regions where temperature is high. However, the association between molecular evolutionary rates and temperature or latitude has never been tested in Squamata. We used a large dataset including the spatial distributions and environmental variables for 1,651 species of Squamata and compared the contrast of the rates of molecular evolution with the contrast of temperature and latitude between sister species. Using major axis regressions and a new algorithm to choose independent sister species pairs, we found that temperature and absolute latitude were not associated with molecular evolutionary rates. This absence of association in such a diverse ectothermic group questions the mechanisms explaining current pattern of species diversity in Squamata and challenges the presupposed universality of the metabolic theory of ecology

Mode-coupling and nonlinear Landau damping effects in auroral Farley-Buneman turbulence

The fundamental problem of Farley-Buneman turbulence in the auroral $E$-region has been discussed and debated extensively in the past two decades. In the present paper we intend to clarify the different steps that the auroral $E$-region plasma has to undergo before reaching a steady state. The mode-coupling calculation, for Farley-Buneman turbulence, is developed in order to place it in perspective and to estimate its magnitude relative to the anomalous effects which arise through the nonlinear wave-particle interaction. This nonlinear effect, known as nonlinear ``Landau damping'' is due to the coupling of waves which produces other waves which in turn lose energy to the bulk of the particles by Landau damping. This leads to a decay of the wave energy and consequently a heating of the plasma. An equation governing the evolution of the field spectrum is derived and a physical interpration for each of its terms is provided

Publisher Correction: The impact of endothermy on the climatic niche evolution and the distribution of vertebrate diversity.

In the version of this Article originally published, in Fig. 3a the first boundary was incorrectly labelled the "K/T boundary"; it should have read the "K/Pg boundary". The two equations in the main text were incorrectly omitted from the HTML. In the description of the posterior distribution of an ancestral state, the normal distribution was incorrectly described as being "assigned as prior to the node value"; it should have read "assigned as calibration to the node value". In the associated equation (the second equation in the text), the denominator of the last term was incorrectly given as "Node prior"; it should have read "Node calibration". In the same equation, the numerator of the third term on the right-hand side of the equation contained incorrect superscript notation on the x and this is shown in the full equation in the notice below.In the Acknowledgements, the following two sentences were incorrectly omitted: "The authors thank the Vital-IT facilities of the Swiss Institute of Bioinformatics for the computational support" and "This work was funded by the University of Lausanne and the Swiss National Science Foundation (CRSIII3-147630) to N.S." In the Author contributions section, the first sentence was incorrectly given as "J.R. designed the study. J.R., N.S. and D. Silvestro designed the methodology and ran the analyses"; it should have read "J.R., D.S. and N.S. designed the study and the methodology". In the Supplementary Information, all three instances of the word "prior" were incorrect and should have read "calibration".These errors have now been corrected in all versions of the Article

Chorus source region localization in the Earth's outer magnetosphere using THEMIS measurements

Discrete ELF/VLF chorus emissions, the most intense electromagnetic plasma waves observed in the Earth's radiation belts and outer magnetosphere, are thought to propagate roughly along magnetic field lines from a localized source region near the magnetic equator towards the magnetic poles. THEMIS project Electric Field Instrument (EFI) and Search Coil Magnetometer (SCM) measurements were used to determine the spatial scale of the chorus source localization region on the day side of the Earth's outer magnetosphere. We present simultaneous observations of the same chorus elements registered onboard several THEMIS spacecraft in 2007 when all the spacecraft were in the same orbit. Discrete chorus elements were observed at 0.15–0.25 of the local electron gyrofrequency, which is typical for the outer magnetosphere. We evaluated the Poynting flux and wave vector distribution and obtained chorus wave packet quasi-parallel propagation to the local magnetic field. Amplitude and phase correlation data analysis allowed us to estimate the characteristic spatial correlation scale transverse to the local magnetic field to be in the 2800–3200 km range

Non-diffusive resonant acceleration of electrons in the radiation belts

International audienceWe describe a mechanism of resonant electron acceleration by oblique high-amplitude whistlerwaves under conditions typical for the Earth radiation belts. We use statistics of spacecraftobservations of whistlers in the Earth radiation belts to obtain the dependence of the angle hbetween the wave-normal and the background magnetic field on magnetic latitude k. According tothis statistics, the angle h already approaches the resonance cone at k 15 and remains close to itup to k 30–40 on the dayside. The parallel component of the electrostatic field of whistlerwaves often increases around k 15 up to one hundred of mV/m. We show that due to thisincrease of the electric field, the whistler waves can trap electrons into the potential well via waveparticle resonant interaction corresponding to Landau resonance. Trapped electrons then move withthe wave to higher latitudes where they escape from the resonance. Strong acceleration is favoredby adiabatic invariance along the increasing magnetic field, which continuously transfers theparallel energy gained to perpendicular energy, allowing resonance to be reached and maintained.The concomitant increase of the wave phase velocity allows for even stronger relative accelerationat low energy <50 keV. Each trapping-escape event of electrons of 10 keV to 100 keV results inan energy gain of up to 100 keV in the inhomogeneous magnetic field of the Earth dipole. Forelectrons with initial energy below 100 keV, such rapid acceleration should hasten their drop intothe loss-cone and their precipitation into the atmosphere. We discuss the role of the consideredmechanism in the eventual formation of a trapped distribution of relativistic electrons for initialenergies larger than 100 keV and in microbursts precipitations of lower energy particles

Higher vitamin D dietary intake is associated with lower risk of alzheimer&#039;s disease: a 7-year follow-up

BACKGROUND: Hypovitaminosis D is associated with cognitive decline among older adults. The relationship between vitamin D intakes and cognitive decline is not well understood. Our objective was to determine whether the dietary intake of vitamin D was an independent predictor of the onset of dementia within 7 years among women aged 75 years and older.METHODS: Four hundred and ninety-eight community-dwelling women (mean, 79.8 3.8 years) free of vitamin D supplements from the EPIDemiology of OSteoporosis Toulouse cohort study were divided into three groups according to the onset of dementia within 7 years (ie, no dementia, Alzheimer\u27s disease [AD], or other dementias). Baseline vitamin D dietary intakes were estimated from self-administered food frequency questionnaire. Age, body mass index, initial cognitive performance, education level, physical activity, sun exposure, disability, number of chronic diseases, hypertension, depression, use of psychoactive drugs, and baseline season were considered as potential confounders. RESULTS: Women who developed AD (n = 70) had lower baseline vitamin D intakes (mean, 50.3 19.3 mug/wk) than nondemented (n = 361; mean intake = 59.0 29.9 mug/wk, p = .027) or those who developed other dementias (n = 67; mean intake = 63.6 38.1 mug/wk, p = .010). There was no difference between other dementias and no dementia (p = .247). Baseline vitamin D dietary intakes were associated with the onset of AD (adjusted odds ratio = 0.99 [95% confidence interval = 0.98-0.99], p = .041) but not with other dementias (p = .071). Being in the highest quintile of vitamin D dietary intakes was associated with a lower risk of AD compared with the lower 4 quintiles combined (adjusted odds ratio = 0.23 [95% confidence interval = 0.08-0.67], p = .007). CONCLUSIONS: Higher vitamin D dietary intake was associated with a lower risk of developing AD among older women

Gait speed, body composition, and dementia. The EPIDOS-Toulouse cohort

BACKGROUND: Slow gait speed (GS) predicts dementia, but this association might be mediated by body composition parameters like total fat mass (TFM) or total lean mass (TLM). The aim of the study was to evaluate whether GS, TLM, and TFM were associated factors with an increased risk for subsequent dementia in community-dwelling older women.METHODS: A case-control study was nested in the EPIDemiologie de l\u27OSteoporose cohort. GS (at usual pace more than 6 m), TLM, and TFM (assessed by dual energy x-ray absorptiometry) were measured at baseline. Cognitive performance was evaluated at baseline and at 7 years of follow-up. The presence of dementia was assured by two blinded memory experts based on best practice and validated criteria. Multivariate logistic regression models assessed the association of GS, TLM, and TFM with dementia risk. RESULTS: Of the initial 1,462 women, 75 years old and older, 647 (43.4%) were cognitively intact at baseline and had a full cognitive assessment at 7 years (145 of them developed dementia). Controlled for covariates (demographics, physical activity, self-reported disabilities, and comorbidities), GS was an independent associated factor for subsequent dementia as a continuous variable (odds ratio [OR] 2.28, 95% CI: 1.32-3.94) and as a categorized variable (OR 2.38, 95% CI: 1.28-4.43 highest vs lowest quartile). Neither interaction with GS nor a statistically significant association with dementia risk was found for TLM and TFM. CONCLUSIONS: GS was an independent associated factor for subsequent dementia not mediated by TLM or TFM

North western Alps Holocene paleohydrology recorded by flooding activity in Lake Le Bourget, France and possible relations with Mont-Blanc glaciers fluctuations

International audienceA 14-m long piston core was retrieved from Lake Le Bourget, NWAlps (France), in order to provide a continuous record of flooding events of the Rhone River during the Holocene. The selection of the coring site was based on high resolution seismic profiling, in an area with limited mass wasting deposits and accumulated proximal Rhone River inter-and underflow deposits. The age-depth model of this core is based on (i) 14 AMS radiocarbon dates, (ii)radionuclide dating(137Cs) and (iii) the identification of historical data (flood events, eutrophication of the lake).The sedimentary record dates back to 9400 cal BP, and includes a thin mass wasting event deposited around 4500 cal BP. A multi-proxy approach was used to track the evolution and origin of clastic sedimentation during the Holocene, in order to identify periods of higher hydrologic al activity in the catchment area. Spectrophotometry was used to detect fluctuations in clastic supply and the study of clay minerals (especially the Illite crystallinity index) allowed locating the main source area of fine grained clastic particles settling at the lake after flood events. This dataset highlights up to 12 periods of more intense flooding events over the last 9400 years in Lake Le Bourget and shows that the main source area of clastic particles during this period is the upper part of the Arve River drainage basin. This part of the catchment area drains several large glaciers from the Mont-Blanc Massif, and fluctuations in Rhone River flood supply in Lake Le Bourget is interpreted as resulting essentially from Mont-Blanc Glacier activity during the Holocene.The comparison of clastic sedimentationin Lake Le Bourget with periods of increasing land use and periods of Alpine glacier and mid-European lake level fluctuations, suggest that the core LDB04 clastic record in Lake Le Bourget is a continuous proxy of the Holocene hydrologic al history of the NW Alps

Dietary Vitamin D Intake and Muscle Mass in Older Women. Results from a Cross-Sectional Analysis of the Epidos Study

Objectives: Vitamin D intake may prevent physical performance decline through prevention of muscle mass loss. Our objective was to determine whether low dietary intakes were associated with low muscle mass (MM). Design and participants: Cross-sectional analysis of 1989 community-dwelling women (mean age 80.5 +/- 3.8years) from the EPIDemiologie de l\u27OSteoporose (EPIDOS) study were assessed at baseline. Measurements: Low intakes of vitamin D (&lt;70 mu g/week) were estimated from the weekly dietary vitamin D intakes (self-administered food frequency questionnaire). Low MM was defined according to the appendicular skeletal muscle mass index assessed using Dual Energy X-ray Absorptiometry, divided by square height of less than 5.45 kg/m(2). Usual gait speed defined physical performance. Age, sun exposure, co-morbidities, education level, living arrangements, recreational physical activity, dietary protein and calcium intakes, bone mineral density, handgrip strength, and body mass index were considered as potential confounders. Multivariate logistic regression analyses assessed the association between low vitamin D intakes and low MM. Results: Two-hundred and nine (10.5%) women with low MM were compared to 1,780 women with normal MM. In final model, obesity/overweight (Adjusted Odds Ratios, aOR=0.09; 95%CI [0.05-0.17]), malnutrition (aOR=3.90; 95%CI [2.74-5.54]) and low handgrip strength (aOR=2.33; 95%CI [1.44-3.77]; p&lt;0.001) were statistically associated with a low MM status. Conclusion: No association with low MM has been reported regarding low dietary intakes of vitamin D