Production of few-layer phosphorene by liquid exfoliation of black phosphorus

We report the liquid exfoliation of black phosphorus to form few-layer phosphorene nanosheets.</p

AtomSim: web-deployed atomistic dynamics simulator

AtomSim, a collection of interfaces for computational crystallography simulations, has been developed. It uses forcefield-based dynamics through physics engines such as the General Utility Lattice Program, and can be integrated into larger computational frameworks such as the Virtual Neutron Facility for processing its dynamics into scattering functions, dynamical functions etc. It is also available as a Google App Engine-hosted web-deployed interface. Examples of a quartz molecular dynamics run and a hafnium dioxide phonon calculation are presented

Black Phosphorus with Near-Superhydrophic Properties and Long-Term Stability in Aqueous Media

Black phosphorus is a two-dimensional material that has potential applications in energy storage, high frequency electronics and sensing, yet it suffers from instability in oxygenated and/or aqueous systems. Here we present the use of a polymeric stabilizer which prevents the degradation of nearly 68% of the material in aqueous media over the course of ca. 1 month

Competition for Cooperation: variability, benefits and heritability of relational wealth in hunter-gatherers

Many defining human characteristics including theory of mind, culture and language relate to our sociality, and facilitate the formation and maintenance of cooperative relationships. Therefore, deciphering the context in which our sociality evolved is invaluable in understanding what makes us unique as a species. Much work has emphasised group-level competition, such as warfare, in moulding human cooperation and sociality. However, competition and cooperation also occur within groups; and inter-individual differences in sociality have reported fitness implications in numerous non-human taxa. Here we investigate whether differential access to cooperation (relational wealth) is likely to lead to variation in fitness at the individual level among BaYaka hunter-gatherers. Using economic gift games we find that relational wealth: a) displays individual-level variation; b) provides advantages in buffering food risk, and is positively associated with body mass index (BMI) and female fertility; c) is partially heritable. These results highlight that individual-level processes may have been fundamental in the extension of human cooperation beyond small units of related individuals, and in shaping our sociality. Additionally, the findings offer insight in to trends related to human sociality found from research in other fields such as psychology and epidemiology

The Extragalactic Distance Database: All Digital HI Profile Catalog

An important component of the Extragalactic Distance Database (EDD) at http://edd.ifa.hawaii.edu is a group of catalogs related to the measurement of HI line profile parameters. One of these is the All Digital HI catalog which contains an amalgam of information from new data and old. The new data results from observations with Arecibo and Parkes telescopes and with the Green Bank Telescope (GBT), including continuing input since the award of the NRAO Cosmic Flows Large Program. The old data has been collected from archives, wherever available, particularly the Cornell University Digital HI Archive, the Nancay Telescope extragalactic HI archive, and the Australia Telescope archive. The catalog currently contains information on ~15,000 profiles relating to ~13,000 galaxies. The channel - flux per channel files, from whatever source, are carried through a common pipeline. The derived parameter of greatest interest is W_m50, the profile width at 50% of the mean flux. After appropriate adjustment, the parameter W_mx is derived, the linewidth which statistically approximates the peak to peak maximum rotation velocity before correction for inclination, 2 V_max sin(i).Comment: 19 pages, 22 figures, Astronomical Journal (anticipated 2009, December

Sexual selection protects against extinction

Reproduction through sex carries substantial costs, mainly because only half of sexual adults produce offspring. It has been theorised that these costs could be countered if sex allows sexual selection to clear the universal fitness constraint of mutation load. Under sexual selection, competition between (usually) males, and mate choice by (usually) females create important intraspecific filters for reproductive success, so that only a subset of males gains paternity. If reproductive success under sexual selection is dependent on individual condition, which depends on mutation load, then sexually selected filtering through ‘genic capture’ could offset the costs of sex because it provides genetic benefits to populations. Here, we test this theory experimentally by comparing whether populations with histories of strong versus weak sexual selection purge mutation load and resist extinction differently. After evolving replicate populations of the flour beetle Tribolium castaneum for ~7 years under conditions that differed solely in the strengths of sexual selection, we revealed mutation load using inbreeding. Lineages from populations that had previously experienced strong sexual selection were resilient to extinction and maintained fitness under inbreeding, with some families continuing to survive after 20 generations of sib × sib mating. By contrast, lineages derived from populations that experienced weak or non-existent sexual selection showed rapid fitness declines under inbreeding, and all were extinct after generation 10. Multiple mutations across the genome with individually small effects can be difficult to clear, yet sum to a significant fitness load; our findings reveal that sexual selection reduces this load, improving population viability in the face of genetic stress

The SAMI Galaxy Survey: Bayesian Inference for Gas Disk Kinematics using a Hierarchical Gaussian Mixture Model

We present a novel Bayesian method, referred to as Blobby3D, to infer gas kinematics that mitigates the effects of beam smearing for observations using Integral Field Spectroscopy (IFS). The method is robust for regularly rotating galaxies despite substructure in the gas distribution. Modelling the gas substructure within the disk is achieved by using a hierarchical Gaussian mixture model. To account for beam smearing effects, we construct a modelled cube that is then convolved per wavelength slice by the seeing, before calculating the likelihood function. We show that our method can model complex gas substructure including clumps and spiral arms. We also show that kinematic asymmetries can be observed after beam smearing for regularly rotating galaxies with asymmetries only introduced in the spatial distribution of the gas. We present findings for our method applied to a sample of 20 star-forming galaxies from the SAMI Galaxy Survey. We estimate the global H$\alpha$ gas velocity dispersion for our sample to be in the range $\bar{\sigma}_v \sim$[7, 30] km s$^{-1}$. The relative difference between our approach and estimates using the single Gaussian component fits per spaxel is $\Delta \bar{\sigma}_v / \bar{\sigma}_v = - 0.29 \pm 0.18$ for the H$\alpha$ flux-weighted mean velocity dispersion.Comment: 23 pages, 12 figures, accepted for MNRA

The SAMI galaxy survey: gas velocity dispersions in low-z star-forming galaxies and the drivers of turbulence

We infer the intrinsic ionized gas kinematics for 383 star-forming galaxies across a range of integrated star formation rates (SFR ∈ [10−3, 102] M⊙ yr−1) at z ≲ 0.1 using a consistent 3D forward-modelling technique. The total sample is a combination of galaxies from the Sydney-AAO Multiobject Integral field Spectrograph (SAMI) Galaxy survey and DYnamics of Newly Assembled Massive Objects survey. For typical low-z galaxies taken from the SAMI Galaxy Survey, we find the vertical velocity dispersion (σv,z) to be positively correlated with measures of SFR, stellar mass, H I gas mass, and rotational velocity. The greatest correlation is with SFR surface density (ΣSFR). Using the total sample, we find σv,z increases slowly as a function of integrated SFR in the range SFR ∈ [10−3, 1]  M⊙ yr−1 from 17 +- 3 to 24 +- 5 km s−1 followed by a steeper increase up to σv,z ∼80 km s−1 for SFR ≳ 1 M⊙ yr−1. This is consistent with recent theoretical models that suggest a σv,z floor driven by star formation feedback processes with an upturn in σv,z at higher SFR driven by gravitational transport of gas through the disc.The SAMI Galaxy Survey is based on observations made at the AAT. The SAMI was developed jointly by the University of Sydney and the Australian Astronomical Observatory. The SAMI input catalogue is based on data taken from the SDSS, the GAMA Survey, and the VST ATLAS Survey. The SAMI Galaxy Survey is supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions, through project number CE170100013, the Australian Research Council Centre of Excellence for All-sky Astrophysics, through project number CE110001020, and other participating institutions. The SAMI Galaxy Survey website is http://sami-survey.org/. DBF and KG acknowledge support from the Australian Research Council Discovery Program grant DP160102235. DBF acknowledges support from Australian Research Council Future Fellowship FT170100376. LC is the recipient of an Australian Research Council Future Fellowship (FT180100066) funded by the Australian Government. MRK acknowledges support from Australian Research Council Future Fellowship FT180100375, and from a Humboldt Research Award from the Alexander von Humboldt Foundation. JJB acknowledges support of an Australian Research Council Future Fellowship (FT180100231). CF acknowledges funding provided by the Australian Research Council (Discovery Projects DP170100603 and Future Fellowship FT180100495), and the Australia-Germany Joint Research Cooperation Scheme (UADAAD). BG is the recipient of an Australian Research Council Future Fellowship (FT140101202). MSO acknowledges the funding support from the Australian Research Council through a Future Fellowship (FT140100255). JvdS is funded under JBH’s ARC Laureate Fellowship (FL140100278)