409 research outputs found
Social license to automate batteries? Australian householder conditions for participation in Virtual Power Plants
Energy companies and new aggregation businesses have recently promoted Virtual Power Plants (VPPs) to solve many problems in energy systems by aggregating and coordinating rooftop solar and household batteries to act in unison. If successful, they could support deployment of renewable generation into electricity distribution networks and enable households to access multiple value streams for their assets, through participation in markets for wholesale energy and system services and payments for network support. However, while residential battery purchase may be more financially attractive if combined with VPP participation, households remain cautious about participation. This paper examines the social factors behind this gap between industry promise and the very low household uptake of VPPs in Australia. We present the key findings from a qualitative study (n = 47) of Australian residential energy users' motivations towards, and conditions for, participation in a hypothetical battery-based virtual power plant. We find that users' willingness to participate in a VPP is affected by their motivations for solar and battery purchase. In particular, VPP participation can conflict with goals of independence from the grid and security of supply. Furthermore, the financial benefits may be more attractive to households who have not already embarked on a ‘sustainability journey’ by purchasing solar and/or a battery. We also find that environmental and social benefits can help motivate VPP participation, provided transparency and fairness in the distribution of benefits are assured through regulation or operation by a trusted broker
Determinants of short-period heart rate variability in the general population
Decreased heart rate variability (HRV) is associated with a worse prognosis in a variety of diseases and disorders. We evaluated the determinants of short-period HRV in a random sample of 149 middle-aged men and 137 women from the general population. Spectral analysis was used to compute low-frequency (LF), high-frequency (HF) and total-frequency power. HRV showed a strong inverse association with age and heart rate in both sexes with a more pronounced effect of heart rate on HRV in women. Age and heart rate-adjusted LF was significantly higher in men and HF higher in women. Significant negative correlations of BMI, triglycerides, insulin and positive correlations of HDL cholesterol with LF and total power occurred only in men. In multivariate analyses, heart rate and age persisted as prominent independent predictors of HRV. In addition, BMI was strongly negatively associated with LF in men but not in women, We conclude that the more pronounced vagal influence in cardiac regulation in middle-aged women and the gender-different influence of heart rate and metabolic factors on HRV may help to explain the lower susceptibility of women for cardiac arrhythmias. Copyright (C) 2001 S. Karger AG, Basel
Sensitivity studies for the cubic-kilometre deep-sea neutrino telescope KM3NeT
The observation of high-energy neutrinos from astrophysical sources would
substantially improve our knowledge and understanding of the non-thermal
processes in these sources, and would in particular pinpoint the accelerators
of cosmic rays. The sensitivity of different design options for a future
cubic-kilometre scale neutrino telescope in the Mediterranean Sea is
investigated for generic point sources and in particular for some of the
galactic objects from which TeV gamma emmission has recently been observed by
the H.E.S.S. atmospheric Cherenkov telescope. The effect of atmospheric
background on the source detection probabilities has been taken into account
through full simulation. The estimated event rates are compared to previous
results and limits from present neutrino telescopes.Comment: 4 pages, 1 figure, contribution of the 30th International Cosmic Ray
conferenc
Characteristics and outcome of patients with ST elevation versus non-ST elevation myocardial infarction: results of the MONICA Augsburg Myocardial Infarction Registry 1985–1995
Novel conopeptides of the I-superfamily occur in several clades of cone snails
The I-superfamily of conotoxins represents a new class of peptides in the venom of some Conus species. These toxins are characterized by four disulfide bridges and inhibit or modify ion channels of nerve cells. When testing venoms from 11 Conus species for a functional characterization, blocking activity on potassium channels (like Kv1.1 and Kv1.3 channels, but not Kv1.2 channels) was detected in the venom of Conus capitaneus, Conus miles, Conus vexillum and Conus virgo. Analysis at the cDNA level of these venoms using primers designed according to the amino acid sequence of a potassium channel blocking toxin (ViTx) from C. virgo confirmed the presence of structurally homologous peptides in these venoms. Moreover, peptides belonging to the I-superfamily, but with divergent amino acid sequences, were found in Conus striatus and Conus imperialis. In all cases, the sequences of the precursors' prepro-regions exhibited high conservation, whereas the sequences of the mature peptides ranged from almost identical to highly divergent between species. We then performed phylogenetic analyses of new and published mitochondrial 16S rDNA sequences representing 104 haplotypes from these and numerous other Conus species, using Bayesian, maximum-likelihood, maximum-parsimony and neighbor-joining methods of inference. Cone snails known to possess I-superfamily toxins were assigned to five different major clades in all of the resulting gene trees. Moreover, I-superfamily conopeptides were detected both in vermivorous and piscivorous species of Conus, thus demonstrating the widespread presence of such toxins in this speciose genus beyond evolutionary and ecological groups
Influence of NixMn1−x thickness and composition on the Curie temperature of Ni in NixMn1−x/Ni bilayers on Cu3Au(001)
We present a magneto-optical Kerr effect study of epitaxial bilayers
consisting of Ni and NixMn1−x on Cu3Au(001). The bottom Ni layer, the NixMn1−x
layer thickness and its chemical composition were changed and the Curie
temperature of the system was determined. We focused on two different regimes
of NixMn1−x composition, namely a Mn-rich with x between 0.25 and 0.5, and a
Ni-rich with x around 0.7. In these two composition ranges, a NixMn1−x
overlayer exhibits a different effect on the Curie temperature of the Ni
layer. While Mn-rich NixMn1−x layers reduce the Curie temperature of the Ni
underlayer, Ni-rich NixMn1−x layers enhance the Curie temperature with respect
to the pure Ni film. This is attributed to changes in the effective thickness
of the Ni layer by exchange interactions with the NixMn1−x overlayer
Short- and intermediate-term survival after extracorporeal membrane oxygenation in children with cardiac disease
ObjectivesIn children with cardiac disease, common indications for extracorporeal membrane oxygenation (ECMO) include refractory cardiopulmonary resuscitation (E-CPR), failure to separate from cardiopulmonary bypass (OR-ECMO), and low cardiac output syndrome (LCOS-ECMO). Despite established acceptance, ECMO outcomes are suboptimal with a survival between 38% and 55%. We evaluated factors associated with significantly increased survival in cardiac patients requiring ECMO.MethodsWe conducted a retrospective investigation of consecutive patients undergoing ECMO between 2006 and 2010. Demographic, pre-ECMO, ECMO, and post-ECMO parameters were analyzed. Neurologic outcomes were assessed with the pediatric overall performance category scale at the latest follow-up.ResultsThere were 3524 admissions, 95 (3%) of which necessitated ECMO; 40 (42%) E-CPR, 31 (33%) OR-ECMO, and 24 (25%) LCOS-ECMO. The overall hospital survival was 73%. The within-groups hospital survival was 75% in E-CPR, 77% OR-ECMO and 62% LCOS-ECMO. In the multivariable logistic regression analysis, chromosomal anomalies (odds ratio [OR], 8; 95% confidence interval [CI], 2-35), single ventricle (OR ,6; 95% CI, 3-33), multiple ECMO runs (OR, 15; 95% CI, 4-42), higher 24-hour ECMO flows (OR, 8; 95% CI, 4-22), decreased lung compliance (OR, 5; 95% CI, 2-16), and need for plasma exchange (OR, 5; 95% CI, 3-18) were all significant factors associated with mortality. From the univariate analysis, a common parameter associated with mortality within all groups was intracranial hemorrhage. At 1.9 years (0.9, 2.9) of follow-up, 66% were still alive, and 89% of survivors had normal function or only mild neurodevelopmental disability.ConclusionsECMO was successfully used in children with cardiac disease with 73% and 66% short- and intermediate-term survival, respectively. The majority of the survivors had normal function or only a minimal neurodevelopmental deficit
Magnetostatic coupling of 90° domain walls in Fe19Ni81/Cu/Co trilayers
The magnetic interlayer coupling of Fe19Ni81/Cu/Co trilayered microstructures
has been studied by means of x-ray magnetic circular dichroism in combination
with photoelectron emission microscopy (XMCD-PEEM). We find that a parallel
coupling between magnetic domains coexists with a non-parallel coupling
between magnetic domain walls (DWs) of each ferromagnetic layer. We attribute
the non-parallel coupling of the two magnetic layers to local magnetic stray
fields arising at DWs in the magnetically harder Co layer. In the magnetically
softer FeNi layer, non-ordinary DWs, such as 270° and 90° DWs with overshoot
of the magnetization either inwards or outwards relative to the turning
direction of the Co magnetization, are identified. Micromagnetic simulations
reveal that in the absence of magnetic anisotropy, both types of overshooting
DWs are energetically equivalent. However, if a uniaxial in-plane anisotropy
is present, the relative orientation of the DWs with respect to the anisotropy
axis determines which of these DWs is energetically favorable
Iron porphyrin molecules on Cu(001): Influence of adlayers and ligands on the magnetic properties
The structural and magnetic properties of Fe octaethylporphyrin (OEP)
molecules on Cu(001) have been investigated by means of density functional
theory (DFT) methods and X-ray absorption spectroscopy. The molecules have been
adsorbed on the bare metal surface and on an oxygen-covered surface, which
shows a reconstruction. In order to allow
for a direct comparison between magnetic moments obtained from sum-rule
analysis and DFT we calculate the dipolar term , which is also
important in view of the magnetic anisotropy of the molecule. The measured
X-ray magnetic circular dichroism shows a strong dependence on the photon
incidence angle, which we could relate to a huge value of , e.g. on
Cu(001) amounts to -2.07\,\mbo{} for normal incidence leading to a
reduction of the effective spin moment . Calculations have also
been performed to study the influence of possible ligands such as Cl and O
atoms on the magnetic properties of the molecule and the interaction between
molecule and surface, because the experimental spectra display a clear
dependence on the ligand, which is used to stabilize the molecule in the gas
phase. Both types of ligands weaken the hybridization between surface and
porphyrin molecule and change the magnetic spin state of the molecule, but the
changes in the X-ray absorption are clearly related to residual Cl ligands.Comment: 17 figures, full articl
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