14,774 research outputs found
Local Density Approximation Description of Electronic Properties of Wurtzite Cadmium Sulfide (w-CdS)
We present calculated, electronic and related properties of wurtzite cadmium
sulfide (w-CdS). Our ab-initio, non-relativistic calculations employed a local
density functional approximation (LDA) potential and the linear combination of
atomic orbitals (LCAO). Following the Bagayoko, Zhao, and Williams (BZW)
method, we solved self-consistently both the Kohn-Sham equation and the
equation giving the ground state density in terms of the wave functions of the
occupied states. Our calculated, direct band gap of 2.47 eV, at the point, is
in excellent agreement with experiment. So are the calculated density of states
and the electron effective mass. In particular, our results reproduce the peaks
in the conduction band density of states, within the experimental
uncertainties.Comment: 22 Pages 4 Figure
International Growth And Human Resource Management Challenges: A Review Of Hewlett-Packards Efforts To Maintain The HP Way
This case is about Hewlett-Packard, its culture, and the problems the company encountered as it made a journey from a domestic firm to an international organization. The case discusses how the culture was created, developed, and perhaps lost during the company battle to stay in the top of the computer, test and measurement instrument markets. This case discusses the national and international challenges that HP has to deal with and the changes the company has to make in order to save the HP way
The medicalisation of disabled children and young people in child sexual abuse: impacts on prevention, identification, response and recovery in the United Kingdom
Understandings of disability are situated within social, political and economic circumstances. Internationally, medical conceptualisations of disability prevail, influencing policy and practice, creating a discourse which encourages categorisation, diagnosis and prescribed ways of understanding behaviour. This body of knowledge has a profound influence, providing powerful explanatory models of disability. Such discourse excludes other ways of knowing, with little attention paid to competences and the construction of worlds especially from the perspectives of disabled children themselves. This article draws upon a small number of UK qualitative studies which have examined disabled child abuse and included the experiences of disabled children. These studies have highlighted how medicalised notions of disability have led to both medicalised and psychiatrised responses to abuse, which have ill-served disabled children. It could be argued that medicalisation has led to disabled children being labelled as either ‘too disabled’ to be abused or ‘not disabled enough’ to receive an appropriate response which meets their needs; they are also sometimes regarded as showing signs of mental ill health when such signs are more likely to be an understandable manifestation of the trauma of abuse. Evidence collected indicate that much can be learnt from understanding the construction of disabled childhoods and how our current limited exploration of this affects how society prevents, identifies and responds to disabled child abuse and associated trauma. Drawing upon disabled children’s recommendations to ‘see me, hear me and understand me’, this article will argue that in order to protect disabled children and support them to recover from abuse, we need to move away from a tick-box culture of medicalising, categorising, psychiatrising and ‘othering’ to a greater understanding of disabled children’s worlds, and to a rights-based model of disabled child protection whereby we challenge the increased barriers to support faced by disabled children who have experienced abuse
Switchable Genetic Oscillator Operating in Quasi-Stable Mode
Ring topologies of repressing genes have qualitatively different long-term
dynamics if the number of genes is odd (they oscillate) or even (they exhibit
bistability). However, these attractors may not fully explain the observed
behavior in transient and stochastic environments such as the cell. We show
here that even repressilators possess quasi-stable, travelling-wave periodic
solutions that are reachable, long-lived and robust to parameter changes. These
solutions underlie the sustained oscillations observed in even rings in the
stochastic regime, even if these circuits are expected to behave as switches.
The existence of such solutions can also be exploited for control purposes:
operation of the system around the quasi-stable orbit allows us to turn on and
off the oscillations reliably and on demand. We illustrate these ideas with a
simple protocol based on optical interference that can induce oscillations
robustly both in the stochastic and deterministic regimes.Comment: 24 pages, 5 main figure
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Search for lepton flavour violation in the eμ continuum with the ATLAS detector in √s = 7 TeV pp collisions at the LHC
This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e^± μ^∓ continuum using 2.1 fb^(−1) of data collected by the ATLAS detector in √s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95 % C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eμX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for m_t=95 GeV to 30 fb for m_t=1000 GeV
Chiral QCD, General QCD Parameterization and Constituent Quark Models
Several recent papers -using effective QCD chiral Lagrangians- reproduced
results obtained with the general QCD parameterization (GP). These include the
baryon 8+10 mass formula, the octet magnetic moments and the coincidental
nature of the "perfect" -3/2 ratio between the magnetic moments of p and n.
Although we anticipated that the GP covers the case of chiral treatments, the
above results explicitly exemplify this fact. Also we show by the GP that -in
any model or theory (chiral or non chiral) reproducing the results of exact
QCD- the Franklin (Coleman Glashow) sum rule for the octet magnetic moments
must be violated.Comment: 10 pages, Latex; abridged version (same results), removed some
reference
Self-stimulated Emission of Undulator Radiation
We attract attention that interaction of particle in downstream undulator
with its own wavelet emitted in upstream undulator could be as strong as with
the frictional field in undulator itself. This phenomenon could be used for
enhancement of signal from pickup undulators in optical stochastic cooling
methods as well as for increase of damping.Comment: 3 pages, 2 figure
Identification of senescence and death in Emiliania huxleyi and Thalassiosira pseudonana: Cell staining, chlorophyll alterations, and dimethylsulfoniopropionate (DMSP) metabolism
We measured membrane permeability, hydrolytic enzyme, and caspase-like activities using fluorescent cell stains to document changes caused by nutrient exhaustion in the coccolithophore Emiliania huxleyi and the diatom Thalassiosira pseudonana, during batch-culture nutrient limitation. We related these changes to cell death, pigment alteration, and concentrations of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) to assess the transformation of these compounds as cell physiological condition changes. E. huxleyi persisted for 1 month in stationary phase; in contrast, T. pseudonana cells rapidly declined within 10 d of nutrient depletion. T. pseudonana progressively lost membrane integrity and the ability to metabolize 5-chloromethylfluorescein diacetate (CMFDA; hydrolytic activity), whereas E. huxleyi developed two distinct CMFDA populations and retained membrane integrity (SYTOX Green). Caspase-like activity appeared higher in E. huxleyi than in T. pseudonana during the post-growth phase, despite a lack of apparent mortality and cell lysis. Photosynthetic pigment degradation and transformation occurred in both species after growth; chlorophyll a (Chl a) degradation was characterized by an increase in the ratio of methoxy Chl a : Chl a in T. pseudonana but not in E. huxleyi, and the increase in this ratio preceded loss of membrane integrity. Total DMSP declined in T. pseudonana during cell death and DMS increased. In contrast, and in the absence of cell death, total DMSP and DMS increased in E. huxleyi. Our data show a novel chlorophyll alteration product associated with T. pseudonana death, suggesting a promising approach to discriminate nonviable cells in nature
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