860 research outputs found
Recommended from our members
Factors Affecting Habitat Quality for Wintering Wood Thrushes in a Coffee Growing Region in Honduras
Amongst the diversity of taxa that occur in the Neotropics, 200 migratory bird species that breed in temperate North America can be found. Many of these populations have seen significant declines since the 1960s. The Wood Thrush, Hylocichla mustelina, is one such species. Shade coffee and other agroforestry practices show potential for benefiting migratory species, but the quality of coffee habitat and optimal habitat characteristics for Wood Thrushes remain unknown.
I surveyed a spatially complex, agricultural landscape in Honduras outside the recognized winter range of the Wood Thrush and radio-tagged 46 individuals within rustic coffee farms during the winters of 2012 and 2013. I used telemetry data to calculate metrics of habitat quality based on survival and persistence while also collecting detailed vegetation measurements across the landscape and within each home-range. Mixed-effects models were used to explore the relationship of survival, transience, movement, and home-range size to habitat class and microhabitat variables.
Estimates for all four habitat quality metrics fell within the range of previous studies and were significantly related to habitat attributes. Structure, edge habitat, and shade coffee played a key role determining habitat quality.
The variables associated with higher habitat quality in this study suggest that rustic coffee farms have potential to support wintering wood thrush populations. However, estimates of survival may be overly optimistic in the presence of transients, transforming highly fragmented landscapes into winter sinks. This study highlights several gaps in current scientific knowledge about some of the most essential questions of Wood Thrush winter ecology
Probit models for capture-recapture data subject to imperfect detection, individual heterogeneity and misidentification
As noninvasive sampling techniques for animal populations have become more
popular, there has been increasing interest in the development of
capture-recapture models that can accommodate both imperfect detection and
misidentification of individuals (e.g., due to genotyping error). However,
current methods do not allow for individual variation in parameters, such as
detection or survival probability. Here we develop misidentification models for
capture-recapture data that can simultaneously account for temporal variation,
behavioral effects and individual heterogeneity in parameters. To facilitate
Bayesian inference using our approach, we extend standard probit regression
techniques to latent multinomial models where the dimension and zeros of the
response cannot be observed. We also present a novel Metropolis-Hastings within
Gibbs algorithm for fitting these models using Markov chain Monte Carlo. Using
closed population abundance models for illustration, we re-visit a DNA
capture-recapture population study of black bears in Michigan, USA and find
evidence of misidentification due to genotyping error, as well as temporal,
behavioral and individual variation in detection probability. We also estimate
a salamander population of known size from laboratory experiments evaluating
the effectiveness of a marking technique commonly used for amphibians and fish.
Our model was able to reliably estimate the size of this population and
provided evidence of individual heterogeneity in misidentification probability
that is attributable to variable mark quality. Our approach is more
computationally demanding than previously proposed methods, but it provides the
flexibility necessary for a much broader suite of models to be explored while
properly accounting for uncertainty introduced by misidentification and
imperfect detection. In the absence of misidentification, our probit
formulation also provides a convenient and efficient Gibbs sampler for Bayesian
analysis of traditional closed population capture-recapture data.Comment: Published in at http://dx.doi.org/10.1214/14-AOAS783 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Effects of Heat Exposure on Body Water Assessed using Single-Frequency Bioelectrical Impedance Analysis and Bioimpedance Spectroscopy
International Journal of Exercise Science 10(7): 1085-1093, 2017. The purpose of this study was to determine if heat exposure alters the measures of total body water (TBW), extracellular water (ECW), and intracellular water (ICW) in both single-frequency bioelectrical impedance analysis (BIA) and bioimpedance spectroscopy (BIS). Additionally, we sought to determine if any differences exist between the BIA and BIS techniques before and after brief exposure to heat. Body water was evaluated for twenty men (age=24±4 years) in a thermoneutral environment (22°C) before (PRE) and immediately after (POST) 15 min of passive heating (35°C) in an environmental chamber. The mean difference and 95% limits of agreement at PRE demonstrated that BIS yielded significantly higher body water values than BIA (all p0.05; 0.2±1.5kg). Additionally, the ES of the mean differences at POST were trivial to small and the r-values were high (r≥0.96). When analyzing the changes in body water before and after heat exposure, POST values for BIS were significantly higher than PRE (all
Interactions with Prompt Problems: A New Way to Teach Programming with Large Language Models
Large Language Models (LLMs) have upended decades of pedagogy in computing
education. Students previously learned to code through \textit{writing} many
small problems with less emphasis on code reading and comprehension. Recent
research has shown that free code generation tools powered by LLMs can solve
introductory programming problems presented in natural language with ease. In
this paper, we propose a new way to teach programming with Prompt Problems.
Students receive a problem visually, indicating how input should be transformed
to output, and must translate that to a prompt for an LLM to decipher. The
problem is considered correct when the code that is generated by the student
prompt can pass all test cases. In this paper we present the design of this
tool, discuss student interactions with it as they learn, and provide insights
into this new class of programming problems as well as the design tools that
integrate LLMs.Comment: accepted for CHI 202
The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III
The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg2 of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg2 of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg2; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra
Direct Measurement of Supra-Physiological Levels of Ascorbate in Plasma using a Nanophotometer
High dose intravenously administered vitamin C (ascorbate) is currently being tested in clinical trials as an adjuvant to current standard of care therapies in a variety of cancers. Intravenous infusion is used with a goal to achieve supraphysiological ascorbate concentrations in blood of at least 20 mM, 300 to 500 times normal healthy concentrations (0.04-0.08 mM). These trials need quick and easy access to information on the levels of ascorbate achieved in the blood to make clinical decisions. Previous methods that quantify ascorbate levels in blood require extensive preparation, time, and materials that may not always be present in clinical settings. We developed a new approach to meet this need using direct UV spectroscopy with a nanophotometer. The only preparation required is centrifugation of whole blood to separate the red blood cells from plasma. No more than 3 microliters of plasma are needed; the approach can determine the concentration of ascorbate in the range of 3 – 35 mM; the method is fast and efficient. This approach has already been deployed to gather this information in a clinical trial with lung cancer patients
Aerocapture Systems Analysis for a Neptune Mission
A Systems Analysis was completed to determine the feasibility, benefit and risk of an aeroshell aerocapture system for Neptune and to identify technology gaps and technology performance goals. The systems analysis includes the following disciplines: science; mission design; aeroshell configuration; interplanetary navigation analyses; atmosphere modeling; computational fluid dynamics for aerodynamic performance and aeroheating environment; stability analyses; guidance development; atmospheric flight simulation; thermal protection system design; mass properties; structures; spacecraft design and packaging; and mass sensitivities. Results show that aerocapture is feasible and performance is adequate for the Neptune mission. Aerocapture can deliver 1.4 times more mass to Neptune orbit than an all-propulsive system for the same launch vehicle and results in a 3-4 year reduction in trip time compared to all-propulsive systems. Enabling technologies for this mission include TPS manufacturing; and aerothermodynamic methods for determining coupled 3-D convection, radiation and ablation aeroheating rates and loads
Understanding the thermo-mechanical behaviour of solid oxide fuel cell anodes using synchrotron X-ray diffraction
The formation of cermet materials via the addition of electrolyte ceramic to metal-based electrodes has become widely adopted in solid oxide fuel cell fabrication due to its benefits in maximizing triple-phase boundary densities, whilst mitigating bulk thermal expansion mismatch between electrode and electrolyte layers. This work improves thermo-mechanical understanding via examination of nickel-based anode materials using synchrotron X-ray diffraction; two cermet materials are studied: Ni-YSZ and Ni-GDC, with comparison to a ceramic-free Ni sample. Findings conclude that although the ceramic addition has minor effects on the cubic Ni structure within isothermal environments, stress induced by the different thermal properties within the cermet materials results in a shifted Ni thermal expansion peak on passing the Curie point. Moreover, extended cycling of the Ni-YSZ sample suggests that low-temperature operation (ca. 600 °C) may require several thermal cycles, or extended dwell times, to alleviate residual Ni stresses, this has potential implications for SOFC design and operation strategies
Dendritic silver self-assembly in molten-carbonate membranes for efficient carbon dioxide capture
Membranes for CO2 capture should offer high permeant fluxes to keep membrane surface area small and material requirements low. Ag-supported, dual-phase, molten-carbonate membranes routinely demonstrate the highest CO2 fluxes in this class of membrane. However, using Ag as a support incurs high cost. Here, the non-equilibrium conditions of permeation were exploited to stimulate the self-assembly of a percolating, dendritic network of Ag from the molten carbonate. Multiple membrane support geometries and Ag incorporation methods were employed, demonstrating the generality of the approach, while X-ray micro-computed tomography confirmed that CO2 and O2 permeation stimulated self-assembly. We report the highest flux of Ag-supported molten-salt membranes to date (1.25 ml min−1 cm−2 at 650 °C) and ultrahigh permeability (9.4 × 10−11 mol m−1 s−1 Pa−1), surpassing the permeability requirement for economically-competitive post-combustion CO2 capture, all whilst reducing the membrane-volume-normalised demand for Ag by one order of magnitude
- …