311 research outputs found
Global Journalist: Photojournalists on working through a pandemic (2020)
In these highlights of a March 20, 2020 Global Journalist webinar, three photographers for West Coast news outlets discuss the challenges they face to keeping the public informed and themselves safe during the COVID-19 pandemic. Hosts: Kat Duncan, Trevor Hook. Guests: Kent Porter, Paige Cornwell, Carlos Gonzalez
Evaluation of the relative potential for contact and doffing transmission of SARS-CoV-2 by a range of personal protective equipment materials
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—the causative agent of coronavirus disease 2019 (COVID-19)—has caused a global public health emergency. Personal protective equipment (PPE) is the primary defence against viral exposure in healthcare and community settings. However, the surfaces of PPE materials may trap virus for contact transmission or through laden aerosols generated during removal of PPE, through cleaning or during movement. In this study, the relative efficacy of current PPE materials in terms of virion adsorption to materials and their antiviral potency, has been evaluated on a wide range of PPE for the first time, including four polymer glove types, two types of scrubs, apron material, a mask, visor and a selection of other commercial polymers and products. Although differences in virion adsorption to the test materials were observed, none of the existing polymer-based PPE resulted in more than tenfold reduction in the SARS-CoV-2 titre within either 10min or 30min contact period. The wettability and surface chemistry of the test materials were analysed to investigate any correlations with their surface physicochemical properties. While no correlation was found between wettability and viral retention under air flow challenge, one secondary ion of m/z 101.03 (+) and three secondary ions of m/z 31.98 (−), 196.93 (−) and 394.33 (+) in ToF–SIMS data of the test materials showed positive and negative correlations with the viral retention, respectively, which was identified by PLS regression model, suggesting that the surface chemistry plays a role in determining the extent of virion adsorption. Our findings outline the material aspects that influence the efficacy of current PPE against SARS-CoV-2 transmission and give suggestions on the development of novel simple polymer-based PPE for better infection protection
The first multi-wavelength campaign of AXP 4U 0142+61 from radio to hard X-rays
For the first time a quasi-simultaneous multi-wavelength campaign has been
performed on an Anomalous X-ray Pulsar from the radio to the hard X-ray band.
4U 0142+61 was an INTEGRAL target for 1 Ms in July 2005. During these
observations it was also observed in the X-ray band with Swift and RXTE, in the
optical and NIR with Gemini North and in the radio with the WSRT. In this paper
we present the source-energy distribution. The spectral results obtained in the
individual wave bands do not connect smoothly; apparently components of
different origin contribute to the total spectrum. Remarkable is that the
INTEGRAL hard X-ray spectrum (power-law index 0.79 +/- 0.10) is now measured up
to an energy of ~230 keV with no indication of a spectral break. Extrapolation
of the INTEGRAL power-law spectrum to lower energies passes orders of magnitude
underneath the NIR and optical fluxes, as well as the low ~30 microJy (2 sigma)
upper limit in the radio band.Comment: 6 pages, 1 figure. To be published in the proceedings of the
conference "Isolated Neutron Stars: from the Interior to the Surface" (April
24-28, 2006, London, UK), eds. S. Zane, R. Turolla and D. Pag
Gemini/GMOS Imaging of Globular Cluster Systems in Five Early-type Galaxies
This paper presents deep high quality photometry of globular cluster (GC)
systems belonging to five early-type galaxies covering a range of mass and
environment. Photometric data were obtained with the Gemini North and Gemini
South telescopes in the filter passbands g', r', and i'. The combination of
these filters with good seeing conditions allows an excellent separation
between GC candidates and unresolved field objects. Bimodal GC colour
distributions are found in all five galaxies. Most of the GC systems appear
bimodal even in the (g' -r') vs (r' -i') plane. A population of
resolved/marginally resolved GC and Ultra Compact Dwarf candidates was found in
all the galaxies. A search for the so-called "blue tilt" in the
colour-magnitude diagrams reveals that NGC 4649 clearly shows that phenomenon
although no conclusive evidence was found for the other galaxies in the sample.
This "blue tilt" translates into a mass-metallicity relation given by Z \propto
M^0.28\pm0.03 . This dependence was found using a new empirical (g' -i') vs
[Z/H] relation which relies on an homogeneous sample of GC colours and
metallicities. This paper also explores the radial trends in both colour and
surface density for the blue (metal-poor) and red (metal-rich) GC
subpopulations. As usual, the red GCs show a steeper radial distribution than
the blue ones. Evidence of galactocentric colour gradients is found in some of
the GC systems, being more significant for the two S0 galaxies in the sample.
Red GC subpopulations show similar colours and gradients to the galaxy halo
stars in their inner region. A GC mean colour-galaxy luminosity relation,
consistent with [Z/H] \propto L_B ^0.26\pm0.08, is present for the red GCs. An
estimate of the total GC populations and specific frequency SN values is
presented for NGC 3115, NGC 3379, NGC 3923 and NGC 4649.Comment: 23 pages, 13 figures and 9 tables. Tables A1 and A2 will be published
in full online only. Accepted for publication in MNRA
Quantum phase transitions from topology in momentum space
Many quantum condensed matter systems are strongly correlated and strongly
interacting fermionic systems, which cannot be treated perturbatively. However,
physics which emerges in the low-energy corner does not depend on the
complicated details of the system and is relatively simple. It is determined by
the nodes in the fermionic spectrum, which are protected by topology in
momentum space (in some cases, in combination with the vacuum symmetry). Close
to the nodes the behavior of the system becomes universal; and the universality
classes are determined by the toplogical invariants in momentum space. When one
changes the parameters of the system, the transitions are expected to occur
between the vacua with the same symmetry but which belong to different
universality classes. Different types of quantum phase transitions governed by
topology in momentum space are discussed in this Chapter. They involve Fermi
surfaces, Fermi points, Fermi lines, and also the topological transitions
between the fully gapped states. The consideration based on the momentum space
topology of the Green's function is general and is applicable to the vacua of
relativistic quantum fields. This is illustrated by the possible quantum phase
transition governed by topology of nodes in the spectrum of elementary
particles of Standard Model.Comment: 45 pages, 17 figures, 83 references, Chapter for the book "Quantum
Simulations via Analogues: From Phase Transitions to Black Holes", to appear
in Springer lecture notes in physics (LNP
Synthesis of novel chlorhexidine spheres with controlled release from a UDMA-HEMA resin using ultrasound
China Scholarship Counci
Towards intensive parenting? Changes in the composition and determinants of mothers' and fathers' time with children 1992-2006
Contemporary expectations of good parenting hold that focused, intensive parental attention is essential to children's development. Parental input is viewed as a key determinant in children's social, psychological and educational outcomes, with the early years particularly crucial. However, increased rates of maternal employment mean that more parents are juggling work and family commitments and have less non-work time available to devote to children. Yet studies find that parental childcare time has increased over recent decades. In this paper, we explore the detail of this trend using data from the Australian Bureau of Statistics (ABS) Time Use Survey (TUS), 1992 and 2006. To investigate whether discourses on intensive parenting are reflected in behaviour, we examine a greater range of parent-child activities than has been undertaken to date, looking at trends in active childcare time (disaggregated into talk-based, physical and accompanying care activities); time in childcare as a secondary activity; time spent in the company of children in leisure activities; and time spent in the company of children in total. We also investigate whether the influence of factors known to predict parental time with children (gender, education, employment status and the age of children) have changed over time. We contextualize our analyses within social and economic trends in Australia and find a compositional change in parental time, with more active childcare occurring within less overall time, which suggests more intensive, child-centred parenting. Fathers' parent-child time, particularly in physical care, increased more than mothers' (from a much lower base), and tertiary education no longer predicts significantly higher childcare time. © London School of Economics and Political Science 2014
The twilight of the Liberal Social Contract? On the Reception of Rawlsian Political Liberalism
This chapter discusses the Rawlsian project of public reason, or public justification-based 'political' liberalism, and its reception. After a brief philosophical rather than philological reconstruction of the project, the chapter revolves around a distinction between idealist and realist responses to it. Focusing on political liberalism’s critical reception illuminates an overarching question: was Rawls’s revival of a contractualist approach to liberal legitimacy a fruitful move for liberalism and/or the social contract tradition? The last section contains a largely negative answer to that question. Nonetheless the chapter's conclusion shows that the research programme of political liberalism provided and continues to provide illuminating insights into the limitations of liberal contractualism, especially under conditions of persistent and radical diversity. The programme is, however, less receptive to challenges to do with the relative decline of the power of modern states
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