46 research outputs found
Structure and Phase transitions of Yukawa balls
In this review, an overview of structural properties and phase transitions in
finite spherical dusty (complex) plasma crystals -- so-called Yukawa balls --
is given. These novel kinds of Wigner crystals can be directly analyzed
experimentally with video cameras. The experiments clearly reveal a shell
structure and allow to determine the shell populations, to observe metastable
states and transitions between configurations as well as phase transitions. The
experimental observations of the static properties are well explained by a
rather simple theoretical model which treats the dust particles as being
confined by a parabolic potential and interacting via an isotropic Yukawa pair
potential. The excitation properties of the Yukawa balls such as normal modes
and the dynamic behavior, including the time-dependent formation of the crystal
requires, in addition, to include the effect of friction between the dust
particles and the neutral gas. Aside from first-principle molecular dynamics
and Monte Carlo simulations several analytical approaches are reviewed which
include shell models and a continuum theory. A summary of recent results and
theory-experiment comparisons is given and questions for future research
activities are outlined.Comment: Invited review, submitted to Contrib. Plasmas Physic
Phototherapy and exchange transfusion for neonatal hyperbilirubinaemia
The purpose of this document is to address the current lack of consensus regarding the management of hyperbilirubinaemia in neonates in South Africa. If left untreated, severe neonatal hyperbilirubinaemia may cause kernicterus and ultimately death and the severity of neonatal jaundice is often underestimated clinically. However, if phototherapy is instituted timeously and at the correct intensity an exchange transfusion can usually be avoided. The literature describing intervention thresholds for phototherapy and exchange transfusion in both term and preterm infants is therefore reviewed and specific intervention thresholds that can be used throughout South Africa are proposed and presented graphically. A simplified version for use in a primary care setting is also presented. All academic heads of neonatology departments throughout South Africa were consulted in the process of drawing up this document and consensus was achieved
The NCI Imaging Data Commons as a platform for reproducible research in computational pathology
Background and Objectives: Reproducibility is a major challenge in developing
machine learning (ML)-based solutions in computational pathology (CompPath).
The NCI Imaging Data Commons (IDC) provides >120 cancer image collections
according to the FAIR principles and is designed to be used with cloud ML
services. Here, we explore its potential to facilitate reproducibility in
CompPath research.
Methods: Using the IDC, we implemented two experiments in which a
representative ML-based method for classifying lung tumor tissue was trained
and/or evaluated on different datasets. To assess reproducibility, the
experiments were run multiple times with separate but identically configured
instances of common ML services.
Results: The AUC values of different runs of the same experiment were
generally consistent. However, we observed small variations in AUC values of up
to 0.045, indicating a practical limit to reproducibility.
Conclusions: We conclude that the IDC facilitates approaching the
reproducibility limit of CompPath research (i) by enabling researchers to reuse
exactly the same datasets and (ii) by integrating with cloud ML services so
that experiments can be run in identically configured computing environments.Comment: 13 pages, 5 figures; improved manuscript, new experiments with P100
GP
Electron and Photon Scattering on Three-Nucleon Bound States
A big spectrum of processes induced by real and virtual photons on the 3He
and 3H nuclei is theoretically investigated through many examples based on
nonrelativistic Faddeev calculations for bound and continuum states. The modern
nucleon-nucleon potential AV18 together with the three-nucleon force UrbanaIX
is used. The single nucleon current is augmented by explicit pi- and rho-like
two-body currents which fulfill the current continuity equation together with
the corresponding parts of the AV18 potential. We also employ the Siegert
theorem, which induces many-body contributions to the current operator. The
interplay of these different dynamical ingredients in the various
electromagnetic processes is studied and the theory is compared to the
experimental data. Overall we find fair to good agreement but also cases of
strong disagreement between theory and experiment, which calls for improved
dynamics. In several cases we refer the reader to the work of other groups and
compare their results with ours. In addition we list a number of predictions
for observables in different processes which would challenge this dynamical
scenario even more stringently and systematically.Comment: 154 pages, 80 figures includes as ps files, 21 additional figures as
jpeg file
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers âŒ99% of the euchromatic genome and is accurate to an error rate of âŒ1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
The SS Cavalry Brigade and its operations in the Soviet Union, 1941-1942
EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Time Out: National Perspectives on Sport and the Covid-19 Lockdown
Chapter 12: Why the NBA Shut Down First: How Partisan Polarization Informs Sports and Public Health, pp. 169-185 is written by University of Nebraska at Omaha professor Daniel N. Hawkins and Andrew M. Lindner. Access this chapter at https://digitalcommons.unomaha.edu/socanthfacpub/27/
In the edited collection Time Out: National Perspectives on Sport and the Covid-19 Lockdown, practitioners and international scholars explore the impact of the global Covid-19 health pandemic on sport from various local and national perspectives. It is part of a two-volume Covid-19 and Sport series that tackles the effects of the global lockdown on sport during March and April 2020, when restrictions were at their most severe and the human toll at its peak in many countries. The chapters provide a comprehensive overview of the immediate consequences of the Covid-19 lockdown on local and national sport. This book presents a variety of interdisciplinary perspectives in a total of twenty-two individual chapters, organized around four main themes. In the first two sections, the authors address the response by professional sports within national contexts. In section three, the authors explore the effects and responses of the Covid-19 lockdown on leisure and amateur sports. The final section assesses the effect of the pandemic on national policies and media.https://digitalcommons.unomaha.edu/socanthfacbooks/1001/thumbnail.jp
Relative distribution, diversity, and bloodmeal sources of mosquitoes and known vectors of Rift Valley fever phlebovirus in three differing ecosystems in Bura, Tana River County, Kenya
Environmental modifications disturb the equilibrium of mosquito populations, altering the risk of mosquito-borne diseases. Mosquito distribution, diversity, and bloodmeal sources were examined to compare Rift Valley fever (RVF) risk among irrigated, riverine, and pastoral ecosystems in Bura, Tana River County, Kenya, between September 2014 and June 2015. Thirty-eight households and 21 irrigation fields were selected for the study. Mosquitoes were trapped with carbon dioxide-impregnated CDC traps, one trap per household and three traps per irrigated field, and morphologically identified using taxonomic keys. Host DNA was extracted from engorged females and cytochrome b genes amplified by PCR to identify sources of bloodmeals. A total of 21,015 mosquitoes were collected; 5742 within households in the 3 ecosystems and 15,273 within irrigated fields. Mosquitoes collected within irrigated fields belonged to 8 genera and 37 species, while those from households within the irrigation scheme belonged to 6 genera and 29 species. Collections from riverine and pastoral households belonged to five and four genera, respectively. The most abundant genera in the irrigated fields were Aedes (21%) and Mansonia (22%), while Anopheles (43%) was the most abundant within households. Most mosquitoes in riverine and pastoral households belonged to Anopheles (76%) and Aedes (65%) genera, respectively. Seasonal variation driven by rainfall was evidenced by spikes in mosquito numbers within irrigated and riverine ecosystems. Host species identification revealed that goats and humans were the main sources of bloodmeal. There was an overall increase in mosquito abundance and diversity as a result of the presence of the irrigated ecosystem in this county, and an increased availability of highly RVF-susceptible hosts as a result of the establishment and concentration of residential areas, promoting potential vectorâhost contacts. These results highlight the impact of anthropogenic changes on mosquito ecology, potentially heightening the risk of transmission and maintenance of RVF in this region