1,073 research outputs found
The brachyopoid Hadrokkosaurus bradyi from the early Middle Triassic of Arizona, and a phylogenetic analysis of lower jaw characters in temnospondyl amphibians
The holotype of the brachyopoid temnospondyl Hadrokkosaurus bradyi, represented by a right lower jaw ramus, is re−ex−
amined based upon new data and revision of various morphological features. Additional fragmentary jaw material re−
ferred to this species is briefly described. Prominent features are a large postsymphyseal foramen that is anteriorly open,
and prearticular and surangular buttresses for support of the articular. Brachyopoid characters include a long and robust
postglenoid area formed by surangular and prearticular, anterior and posterior keels on at least some marginal dentary
teeth, and subtriangular outline of the adductor fossa in dorsal view. Five features of the holotype ramus, long thought to
be at odds with its brachyopoid or temnospondyl nature, are critically re−evaluated. A phylogenetic analysis of lower jaw
characters in temnospondyls retrieves most of the clades found in more comprehensive data sets, but the statistical node
support is low. Brachyopoids are monophyletic, with Hadrokkosaurus emerging as their most basal taxon
Unified model of hyperthermia via hysteresis heating in systems of interacting magnetic nanoparticles
We present a general study of frequency and magnetic field dependence of the
specific heat power produced during field-driven hysteresis cycles in magnetic
nanoparticles with relevance to hyperthermia applications in biomedicine.
Employing a kinetic Monte-Carlo method with natural time scales allows us to go
beyond the assumptions of small driving field amplitudes and negligible
inter-particle interactions, which are fundamental to applicability of the
standard approach based on linear response theory. The method captures the
superparamagnetic and fully hysteretic regimes and the transition between them.
Our results reveal unexpected dipolar interaction-induced enhancement or
suppression of the specific heat power, dependent on the intrinsic statistical
properties of particles, which cannot be accounted for by the standard theory.
Although the actual heating power is difficult to predict because of the
effects of interactions, optimum heating is in the transition region between
the superparamagnetic and fully hysteretic regimes
The tetrapod Caerorhachis bairdi Holmes and Carroll from the Lower Carboniferous of Scotland
The tetrapod Caerorhachis bairdi, probably from the Pendleian Limestone Coal
Group in the Scottish Midland Valley, is redi agnosed and redescribed, and its affinities are
discussed. Caerorachis was originally interpreted as a temnospondyl amphibian, based on
characters that are now regarded as primitive for tetrapods, or of uncertain polarity. Several
features of Caerorhachis (e.g. gastrocentrous vertebrae, curved trunk ribs, reduced dorsal iliac
blade, L-shaped tarsal intermedium) are observed in certain primitive amniotes. In particular,
Caerorhachis resembles ‘anthracosaurs’, generally considered to be among the most primitive of
stem-group amniotes.
The phylogenetic position of Caerorhachis is considered in the light of recently published cladistic
analyses of Palaeozoic tetrapods. Most analyses place Caerorhachis at the base of, or within, ‘anthra-
cosaurs’. When multiple, equally parsimonious solutions are found, its ‘anthracosaur’ affinities are
shown in at least some trees, and are supported by several informative and, generally, highly
consistent characters. Alternative phylogenetic placements (e.g. sister taxon to temnospondyls) are
usually less well corroborated.
If the fundamental evolutionary split of most early tetrapods into stem-group lissamphibians (e.g.
temnospondyl s) and stem-group amniotes (e.g. ‘anthracosaurs’) is accepted, then the revised
interpretation of Caerorhachi s sheds light on near-ancestral conditions for Amniota
Opportunity Zones Providing Opportunity for Whom?: How the Current Regulations Are Failing and a Solution to Uplift Communities
In 2017, the newly enacted Tax Cuts and Jobs Act created an incentive for taxpayers to invest in Qualified Opportunity Zones— census tracts that consist of low-income communities. These investments, which are incentivized via lucrative tax deferral benefits, are intended to uplift communities and leave them in a better position than they were pre-investment. However, the initiative lacks regulation requiring investments to actually benefit low-income areas, resulting in money going to places that do not need help, while communities that are in need may face displacement. This is a result of many wealthy investors finding that luxury projects are the easiest to finance, while others have even lobbied to have state officials designate specific plots of lands, that are not low-income at all, as Opportunity Zones. This Note explores how the Opportunity Zone legislation contributes to the pervasive income and wealth disparities in America and proposes additional regulations that could result in meaningful investments that benefit underserved communities
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Genetic Toolkit for Assessment and Prediction of Population-Level Impacts of Bridge Construction on Birds
Recent studies have highlighted alarming rates of declines in bird populations across the country. The State of California is home to over 650 resident and migrant avian species. Legislation for protecting these species has existed for over a century now, yet tools for identifying populations and understanding seasonal movement remain limited. Recently, genetic and genomic tools have provided a method for understanding population structure, allowing for more informed delineation of management units. The goal of this project was to create a genetic toolkit for identifying breeding populations and assigning individuals to those populations. Ultimately, such tools could be used to assess population-level impacts when there are conflicts with birds at infrastructure construction sites. As a test case, we sequenced entire genomes for 40 individual Anna’s hummingbirds (Calypte anna) from across the state. Based on this initial data, we found low levels of differentiation between sampled locations, suggesting that C. anna in California are not subdivided into different population units. However, there was a weak signal of geography suggesting there may be localized genetic differences in a small proportion of the genome. Follow-up work will focus on a broader sampling across the state of California to clarify any possible population subdivision or geographical patterns of differentiation.View the NCST Project Webpag
Discovery of a giant radio halo in a new Planck galaxy cluster PLCKG171.9-40.7
We report the discovery of a giant radio halo in a new, hot, X-ray luminous
galaxy cluster recently found by Planck, PLCKG171.9-40.7. The radio halo was
found using Giant Metrewave Radio Telescope observations at 235 MHz and 610
MHz, and in the 1.4 GHz data from a NRAO Very Large Array Sky Survey pointing
that we have reanalyzed. The diffuse radio emission is coincident with the
cluster X-ray emission, has an extent of ~1 Mpc and a radio power of ~5x 10^24
W/Hz at 1.4 GHz. Its integrated radio spectrum has a slope of alpha~1.8 between
235 MHz and 1.4 GHz, steeper than that of a typical giant halo. The analysis of
the archival XMM-Newton X-ray data shows that the cluster is hot (~10 keV) and
disturbed, consistent with X-ray selected clusters hosting radio halos. This is
the first giant radio halo discovered in one of the new clusters found by
Planck.Comment: 9 pages, 8 figures and 4 tables. Corrected Figure 7. Matches ApJ
published versio
Discovery of a radio relic in the low mass, merging galaxy cluster PLCK G200.9-28.2
Radio relics at the peripheries of galaxy clusters are tracers of the elusive
cluster merger shocks. We report the discovery of a single radio relic in the
galaxy cluster PLCK G200.9-28.2 (, ) using the Giant Metrewave Radio Telescope at 235 and 610 MHz and
the Karl G. Jansky Very Large Array at 1500 MHz. The relic has a size of Mpc, an arc-like morphology and is located at 0.9 Mpc from the
X-ray brightness peak in the cluster. The integrated spectral index of the
relic is . The spectral index map between 235 and 610 MHz shows
steepening from the outer to the inner edge of the relic in line with the
expectation from a cluster merger shock. Under the assumption of diffusive
shock acceleration, the radio spectral index implies a Mach number of
for the shock. The analysis of archival XMM Newton data shows that
PLCK G200.9-28.2 consists of a northern brighter sub-cluster, and a southern
sub-cluster in a state of merger. This cluster has the lowest mass among the
clusters hosting single radio relics. The position of the Planck Sunyaev
Ze'ldovich effect in this cluster is offset by 700 kpc from the X-ray peak in
the direction of the radio relic, suggests a physical origin for the offset.
Such large offsets in low mass clusters can be a useful tool to select
disturbed clusters and to study the state of merger.Comment: 10 pages, 7 figures, 4 tables. Accepted for publication in MNRA
Beamlike models for the analyses of curved, twisted and tapered horizontal-axis wind turbine (HAWT) blades undergoing large displacements
Abstract. Continuous ongoing efforts to better predict the mechanical behaviour of complex beamlike structures, such as wind turbine blades, are motivated by the need to improve their performance and reduce the costs. However, new design approaches and the increasing flexibility of such structures make their aeroelastic modelling ever more challenging. For the structural part of this modelling, the best compromise between computational efficiency and accuracy can be obtained via schematizations based on suitable beamlike elements. This paper addresses the modelling of the mechanical behaviour of beamlike structures which are curved, twisted and tapered in their unstressed state and undergo large displacements, in- and out-of-plane cross-sectional warping, and small strains. A suitable model for the problem at hand is proposed. Analytical and numerical results obtained by its application are presented and compared with results from 3D FEM analyses
A Non-Sequential Representation of Sequential Data for Churn Prediction
We investigate the length of event sequence giving best predictions
when using a continuous HMM approach to churn prediction from sequential
data. Motivated by observations that predictions based on only the few most recent
events seem to be the most accurate, a non-sequential dataset is constructed
from customer event histories by averaging features of the last few events. A simple
K-nearest neighbor algorithm on this dataset is found to give significantly
improved performance. It is quite intuitive to think that most people will react
only to events in the fairly recent past. Events related to telecommunications occurring
months or years ago are unlikely to have a large impact on a customer’s
future behaviour, and these results bear this out. Methods that deal with sequential
data also tend to be much more complex than those dealing with simple nontemporal
data, giving an added benefit to expressing the recent information in a
non-sequential manner
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