On the Borderline of Pauling\u27s Bond Order Concept: Metal-Metal Bonding in Icosahedral Chains of Metal-Rich Tantalum Sulfides

Metal-metal bonding in the icosahedral metal-rich sulfides of Ta is considered from the point of view of extended Hückel calculations via Mullikan overlap populations and from the point-of-view of Pauling bond order. It is found that the two approaches are generally consistent, but that the overlap populations provide a more sensitive estimate of reaction energies. The results are consistent with a strong stabilization of the icosahedral clusters by central atom to icosahedral metal atom bonding and a weak destabilization (relative to the disproportionation products) by the icosahedral metal atom bonds

A Bayesian model for identifying hierarchically organised states in neural population activity

Neural population activity in cortical circuits is not solely driven by external inputs, but is also modulated by endogenous states. These cortical states vary on multiple time-scales and also across areas and layers of the neocortex. To understand information processing in cortical circuits, we need to understand the statistical structure of internal states and their interaction with sensory inputs. Here, we present a statistical model for extracting hierarchically organized neural population states from multi-channel recordings of neural spiking activity. We model population states using a hidden Markov decision tree with state-dependent tuning parameters and a generalized linear observation model. Using variational Bayesian inference, we estimate the posterior distribution over parameters from population recordings of neural spike trains. On simulated data, we show that we can identify the underlying sequence of population states over time and reconstruct the ground truth parameters. Using extracellular population recordings from visual cortex, we find that a model with two levels of population states outperforms a generalized linear model which does not include state-dependence, as well as models which only including a binary state. Finally, modelling of state-dependence via our model also improves the accuracy with which sensory stimuli can be decoded from the population response

A conservation assessment of the amphibians and reptiles of the Forêt d’Ambre Special Reserve, north Madagascar

We surveyed the lowland rainforest of the Forêt d’Ambre Special Reserve in north Madagascar for amphibians and reptiles. We recorded a total of 20 amphibian and 39 reptile species via opportunistic searching and pitfall trapping in the first published survey to focus on this area. Consequently most of the species found were new records for the area. Approximately half of the species (51 %) were only found in relatively undisturbed areas of forest and 61 % appear to be restricted to lowland rainforest below 900 m elevation. The most vulnerable elements of this herpetofauna are the three species that appear to be locally endemic to Forêt d’Ambre (according to the current knowledge): Boophis baetkei, Brookesia sp. nov., and Rhombophryne sp. nov. An additional 25 species are considered regional endemics, 14 species are threatened according to the 2007 Red List of Threatened Species and 15 species are listed on the CITES appendices. This paper contributes to the current understanding of Malagasy patterns of biodiversity by documenting the composition, geographical and ecological distribution of the herpetofauna found at this site. Despite its protected status, currently the Reserve is not being managed sufficiently as it is subject to numerous human - induced environmental problems resulting in habitat destruction and should therefore be considered a high conservation management priority. Herein, we provide conservation and development recommendations for this highly diverse site of herpetological importance. Furthermore, we provide an updated and revised species list of the amphibians and reptiles of Montagne d’Ambre National Park and a species list for the private Fontenay Nature Park

SCORPIO-II: Spectral indices of weak Galactic radio sources

In the next few years the classification of radio sources observed by the large surveys will be a challenging problem, and spectral index is a powerful tool for addressing it. Here we present an algorithm to estimate the spectral index of sources from multiwavelength radio images. We have applied our algorithm to SCORPIO (Umana et al. 2015), a Galactic Plane survey centred around 2.1 GHz carried out with ATCA, and found we can measure reliable spectral indices only for sources stronger than 40 times the rms noise. Above a threshold of 1 mJy, the source density in SCORPIO is 20 percent greater than in a typical extra-galactic field, like ATLAS (Norris et al. 2006), because of the presence of Galactic sources. Among this excess population, 16 sources per square degree have a spectral index of about zero, suggesting optically thin thermal emission such as Hii regions and planetary nebulae, while 12 per square degree present a rising spectrum, suggesting optically thick thermal emission such as stars and UCHii regions.Comment: 12 pages, 11 figures, accepted by MNRA

Psychological Distress and Well-Being among Students of Health Disciplines: The Importance of Academic Satisfaction

Background: Research on the mental health of students in health disciplines mainly focuses on psychological distress and nursing and medical students. This study aimed to investigate the psychological well-being and distress and related factors among undergraduate students training in eight different health-related tracks in Geneva, Switzerland. Methods: This cross-sectional study used established self-filled scales for anxiety, depression, stress, psychological well-being, and study satisfaction. Descriptive statistics and hierarchical regression analyses were applied. Results: In October 2019, out of 2835 invited students, 915 (32%) completed the survey. Lower academic satisfaction scores were strongly associated with depression (β = −0.26, p < 0.001), anxiety (β = −0.27, p < 0.001), and stress (β = −0.70, p < 0.001), while higher scores were associated with psychological well-being (β = 0.70, p < 0.001). Being female was strongly associated with anxiety and stress but not with depression or psychological well-being. Increased age was associated with enhanced psychological well-being. The nature of the academic training had a lesser impact on mental health and the academic year had none. Conclusion: Academic satisfaction strongly predicts depression, anxiety, stress, and psychological well-being. Training institutions should address the underlying factors that can improve students’ satisfaction with their studies while ensuring that they have access to psychosocial services that help them cope with mental distress and enhance their psychological well-bein

Experimental characterization of frequency dependent squeezed light

We report on the demonstration of broadband squeezed laser beams that show a frequency dependent orientation of the squeezing ellipse. Carrier frequency as well as quadrature angle were stably locked to a reference laser beam at 1064nm. This frequency dependent squeezing was characterized in terms of noise power spectra and contour plots of Wigner functions. The later were measured by quantum state tomography. Our tomograph allowed a stable lock to a local oscillator beam for arbitrary quadrature angles with one degree precision. Frequency dependent orientations of the squeezing ellipse are necessary for squeezed states of light to provide a broadband sensitivity improvement in third generation gravitational wave interferometers. We consider the application of our system to long baseline interferometers such as a future squeezed light upgraded GEO600 detector.Comment: 8 pages, 8 figure

Further Sunyaev-Zel'dovich observations of two Planck ERCSC clusters with the Arcminute Microkelvin Imager

We present follow-up observations of two galaxy clusters detected blindly via the Sunyaev-Zel'dovich (SZ) effect and released in the Planck Early Release Compact Source Catalogue. We use the Arcminute Microkelvin Imager, a dual-array 14-18 GHz radio interferometer. After radio source subtraction, we find a SZ decrement of integrated flux density -1.08+/-0.10 mJy toward PLCKESZ G121.11+57.01, and improve the position measurement of the cluster, finding the centre to be RA 12 59 36.4, Dec +60 04 46.8, to an accuracy of 20 arcseconds. The region of PLCKESZ G115.71+17.52 contains strong extended emission, so we are unable to confirm the presence of this cluster via the SZ effect.Comment: 4 tables, 3 figures, revised after referee's comments and resubmitted to MNRA