3,468 research outputs found
A Note on Solid-State Maxwell Demon
Starting from 2002, at least two kinds of laboratory-testable, solid-state
Maxwell demons have been proposed that utilize the electric field energy of an
open-gap n-p junction and that seem to challenge the validity of the Second Law
of Thermodynamics. In the present paper we present some arguments against the
alleged functioning of such devices.Comment: 9 pages, 4 figures. Foundations of Physics, forthcoming. arXiv admin
note: substantial text overlap with arXiv:1101.505
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Leveraging Epidemiology to Improve Risk Assessment.
The field of environmental public health is at an important crossroad. Our current biomonitoring efforts document widespread exposure to a host of chemicals for which toxicity information is lacking. At the same time, advances in the fields of genomics, proteomics, metabolomics, genetics and epigenetics are yielding volumes of data at a rapid pace. Our ability to detect chemicals in biological and environmental media has far outpaced our ability to interpret their health relevance, and as a result, the environmental risk paradigm, in its current state, is antiquated and ill-equipped to make the best use of these new data. In light of new scientific developments and the pressing need to characterize the public health burdens of chemicals, it is imperative to reinvigorate the use of environmental epidemiology in chemical risk assessment. Two case studies of chemical assessments from the Environmental Protection Agency Integrated Risk Information System database are presented to illustrate opportunities where epidemiologic data could have been used in place of experimental animal data in dose-response assessment, or where different approaches, techniques, or studies could have been employed to better utilize existing epidemiologic evidence. Based on the case studies and what can be learned from recent scientific advances and improved approaches to utilizing human data for dose-response estimation, recommendations are provided for the disciplines of epidemiology and risk assessment for enhancing the role of epidemiologic data in hazard identification and dose-response assessment
Ion acceleration and anomalous transport in the near wake of a plasma limiter
Ion acceleration and anomalous transport were studied experimentally in the near wake region of an electrically floating disk limiter immersed in two different types of collisionless, supersonically flowing, magnetized plasmas: the first initially quiescent, the second initially turbulent. Ion densities and velocity distributions were obtained using a nonperturbing laser induced fluorescence diagnostic. Large-amplitude, low-frequency turbulence was observed at the obstacle edge and in the wake. Rapid ion and electron configuration space transport and ion velocity space transport were observed. Configuration space and velocity space transport were similar for both quiescent and turbulent plasma-obstacle systems, suggesting that plasma-obstacle effects outweigh the effects of initial plasma turbulence levels
Women's perceptions and experiences of breastfeeding support: A metasynthesis
Background: Both peer and professional support have been identified as important to the success of breastfeeding. The aim of this metasynthesis was to examine womenâs perceptions and experiences of breastfeeding support, either professional or peer, in order to illuminate the components of support that they deem âsupportiveâ.
Methods: The metasynthesis included studies of both formal or âcreatedâ peer and professional support for breastfeeding women but excluded studies of family or informal support. Qualitative studies were included as well as large scale surveys if they reported the analysis of qualitative data gathered through open ended responses. Primiparous and multiparous women who initiated breastfeeding were included. Only studies published in English, in peer reviewed journals and undertaken between 1990 and December 2007 were included. After assessment for relevance and quality, 31 studies were included in the metasynthesis. Meta-ethnographic methods were used to identify categories and themes.
Results: The metasynthesis resulted in four categories comprising a total of 20 themes. The synthesis indicates that support for breastfeeding occurs along a continuum from authentic presence at one end, perceived as effective support, to disconnected encounters at the other, perceived as ineffective or even discouraging and counterproductive. Second, the synthesis identified a facilitative approach, versus a reductionist approach as contrasting styles of support women experienced as helpful or unhelpful.
Conclusions: The findings of this metasynthesis emphasise the importance of person-centred communication skills and of relationships in supporting a woman to breastfeed. Organisational systems and services that facilitate continuity of care/r, for example continuity of midwifery care or peer support models, are more likely to facilitate an authentic presence
Findings from an online survey of family carer experience of the management of challenging behaviour in people with intellectual disabilities, with a focus on the use of psychotropic medication
Background: There is relatively little published data that report the experiences and views of family carers of people with intellectual disabilities who display challenging behaviour who are prescribed psychotropic medication. / Materials and methods: An online structured questionnaire was created by the Challenging Behaviour Foundation, a UK charity, and family carers of people with intellectual disability. Questions concerned the management of challenging behaviour and asked family carers about their experiences and views on the use of psychotropic medication. Responses were gathered between August and October 2016. Results are summarised using descriptive and inferential statistics and descriptive analysis of freeâtext comments. / Findings: Ninetyânine family carers completed the survey. Family carers reported gaps in the holistic and proactive management of challenging behaviour. Whilst some felt involved in decisions around psychotropic medication prescribing, others described feeling marginalised and lacking information and influence. The decision to prescribe psychotropic medication evoked complex emotions in family carers and medication use was associated with mixed outcomes in those prescribed. Family carers identified areas of good practice and those areas where they believe improvements are needed. / Conclusions: Psychotropic medication should be only one option in a multimodal approach to challenging behaviour, but this may not always be reflected in current practice. Greater effort needs to be made to ensure that services are equipped to provide optimum care and to embed shared decisionâmaking into routine practice
Redefining the effect of salt on thermophilic starter cell viability, culturability and metabolic activity in cheese
peer-reviewedThis study investigated the differential effect of salt concentration in the outside and inside layers of
brine salted cheeses on viability, culturability and enzyme activity of starter bacteria. The high-salt
environment of the outside layer caused a sharp decrease in L. helveticus viability as measured by
traditional plate counts. Remarkably, this was associated with lower release of intracellular enzymes
(LDH), reduced levels of proteolysis and larger membrane integrity as measured by flow cytometry (FC)
following classical Live/Dead staining. FC analysis of light scattering properties highlighted a significant
reduction in size and granularity of the microbiota located in the cheese surface, suggestive of cell
shrinkage and condensation of internal macromolecules probably due to hyperosmotic stress. The
microbiota of the cheese surface were found to experience greater oxidative stress, as measured by FC
analysis of the total levels of reactive oxygen species, compared to that of the interior layer. These results
lead us to postulate that the physiology and health status of the microbiota were significantly different in
the outer and inner layers of the cheese. The hyperosmotic environment of the outer layer resulted in
reduced cell lysis, as measurable by assays based upon membrane integrity, but rather triggered cell
death via mechanisms involving cell shrinkage and ROS-mediated damage of vital intracellular components.
This study challenges the current thinking on how salt controls microbial activity in ripening
cheese, especially in cheeses which are brine salted as local variations in biochemical ripening indices
can differ significantly from the outside to the inside of a ripening cheese
Report of radio interference test on Fifth Dimension, Inc. multicoder, model no. HDA4M-839, serial no. 7243
Electromagnetic interference and susceptibility testing of multicoder compliance to radio interference requirement
Adjustable levels of strong turbulence in a positive/negative ion plasma
Positive/negative ion plasmas, composed of Ba+, SF6â, and residual electrons, were observed to display characteristics of strong turbulence.Experiments on the UCI Q machine linked the presence of negative ions (and the depletion of electrons) with large density fluctuations (ÎŽn/nâ1), largeâamplitude, lowâfrequency electrostatic noise (fâ€20 kHz), and rapid transport of ions across magnetic field lines (Dâ„â104 cm2/sec). Ion velocity distributions were heated parallel to and cooled perpendicular to the confining magnetic field. The partial pressure of gaseous SF6 was shown to serve as a regulator of plasma turbulence. Turbulence levels could be smoothly varied from quiescent states (ÎŽn/nâ0.01) to strongly turbulent states (ÎŽn/nâ1)
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