3,645 research outputs found
Constraining the nuclear equation of state at subsaturation densities
Only one third of the nucleons in Pb occupy the saturation density
area. Consequently nuclear observables related to average properties of nuclei,
such as masses or radii, constrain the equation of state (EOS) not at
saturation density but rather around the so-called crossing density, localised
close to the mean value of the density of nuclei: 0.11 fm.
This provides an explanation for the empirical fact that several EOS quantities
calculated with various functionals cross at a density significantly lower than
the saturation one. The third derivative M of the energy at the crossing
density is constrained by the giant monopole resonance (GMR) measurements in an
isotopic chain rather than the incompressibility at saturation density. The GMR
measurements provide M=1110 70 MeV (6% uncertainty), whose extrapolation
gives K=230 40 MeV (17% uncertainty).Comment: 4 pages, 4 figure
The development of a juvenile porcine augmented renal clearance model through continuous infusion of lipopolysaccharides : an exploratory study
Augmented renal clearance (ARC) as observed in the critically ill (pediatric) population can have a major impact on the pharmacokinetics and posology of renally excreted drugs. Although sepsis has been described as a major trigger in the development of ARC in human critically ill patients, mechanistic insights on ARC are currently lacking. An appropriate ARC animal model could contribute to reveal these underlying mechanisms. In this exploratory study, a state of ARC was induced in 8-week-old piglets. Conscious piglets were continuously infused over 36 h with lipopolysaccharides (LPS) from Escherichia coli (O111:B4) to induce sepsis and subsequently trigger ARC. To study the dose-dependent effect of LPS on the renal function, three different doses (0.75, 2.0, 5.0 mu g/kg/h) were administered (two male piglets/dose, one sham piglet), in combination with fluid administration (0.9% NaCl) at 6 ml/kg/h. Single boluses of renal markers, i.e., creatinine [40 mg/kg body weight (BW)], iohexol (64.7 mg/kg BW), and para-aminohippuric acid (PAH, 10 mg/kg BW) were administered intravenously to evaluate the effect of LPS on the renal function. Clinical parameters were monitored periodically. Blood sampling was performed to determine the effect on hematology, neutrophil gelatinase-associated lipocalin, and prostaglandin E-2 plasma levels. All piglets that were continuously infused with LPS displayed an elevated body temperature, heart rhythm, and respiratory rate similar to 1-3 h after start of the infusion. After infusion, considerably higher total body clearances of iohexol, creatinine, and PAH were observed, independent of the administration of LPS and/or its dose. Since also the sham piglet, receiving no LPS, demonstrated a comparable increase in renal function, the contribution of fluid administration to the development of ARC should be further evaluated
In-situ Plasma Studies using a Direct Current Microplasma in a Scanning Electron Microscope
Microplasmas can be used for a wide range of technological applications and
to improve our understanding of fundamental physics. Scanning electron
microscopy, on the other hand, provides insights into the sample morphology and
chemistry of materials from the mm-down to the nm-scale. Combining both would
provide direct insight into plasma-sample interactions in real-time and at high
spatial resolution. Up till now, very few attempts in this direction have been
made, and significant challenges remain. This work presents a stable direct
current glow discharge microplasma setup built inside a scanning electron
microscope. The experimental setup is capable of real-time in-situ imaging of
the sample evolution during plasma operation and it demonstrates localized
sputtering and sample oxidation. Further, the experimental parameters such as
varying gas mixtures, electrode polarity, and field strength are explored and
experimental - curves under various conditions are provided. These
results demonstrate the capabilities of this setup in potential investigations
of plasma physics, plasma-surface interactions, and materials science and its
practical applications. The presented setup shows the potential to have several
technological applications, e.g., to locally modify the sample surface (e.g.,
local oxidation and ion implantation for nanotechnology applications) on the
m-scale.Comment: LG, DC, and RDM contributed equally to this work. The videos
mentioned in the manuscript can be found in the Zenodo repository linked in
the pape
Characterizing a cluster's dynamic state using a single epoch of radial velocities
Radial velocity measurements can be used to constrain the dynamical state of
a stellar cluster. However, for clusters with velocity dispersions smaller than
a few km/s the observed radial velocity distribution tends to be dominated by
the orbital motions of binaries rather than the stellar motions through the
potential well of the cluster. Our goal is to characterize the intrinsic
velocity distribution of a cluster from a single epoch of radial velocity data,
even for a cluster with a velocity dispersion of a fraction of a km/s, using a
maximum likelihood procedure. Assuming a period, mass ratio, and eccentricity
distribution for the binaries in the observed cluster this procedure fits a
dynamical model describing the velocity distribution for the single stars and
center of masses of the binaries, simultaneously with the radial velocities
caused by binary orbital motions, using all the information available in the
observed velocity distribution. We find that the fits to the intrinsic velocity
distribution depend only weakly on the binary properties assumed, so the
uncertainty in the fitted parameters tends to be dominated by statistical
uncertainties. Based on Monte Carlo simulations we provide an estimate of how
these statistical uncertainties vary with the velocity dispersion, binary
fraction, and the number of observed stars, which can be used to estimate the
sample size needed to reach a specific accuracy. Finally we test the method on
the well-studied open cluster NGC 188, showing that it can reproduce a velocity
dispersion of only 0.5 km/s using a single epoch of the multi-epoch radial
velocity data. If the binary period, mass ratio, and eccentricity distribution
of the observed stars are roughly known, this procedure can be used to correct
for the effect of binary orbital motions on an observed velocity distribution.
[Abridged]Comment: 11 pages, 6 figures, accepted by A&
Intermittent Surface Oxygenation Results in Similar Mitochondrial Protection and Maintenance of Aerobic Metabolism as Compared to Continuous Oxygenation during Hypothermic Machine Kidney Machine Perfusion
Short bubble and subsequent surface oxygenation is an innovative oxygenation technique and alternative for membrane oxygenation during hypothermic machine perfusion (HMP). The metabolic effect of the interruption of surface oxygenation for 4 h (mimicking organ transport) during HMP was compared to continuous surface and membrane oxygenation in a pig kidney ex situ preservation model. After 30 min of warm ischemia by vascular clamping, a kidney of a ±40 kg pig was procured and subsequently preserved according to one of the following groups: (1) 22-h HMP + intermittent surface oxygenation ( = 12); (2) 22-h HMP + continuous membrane oxygenation ( = 6); and (3) 22-h HMP + continuous surface oxygenation ( = 7). Brief perfusate O uploading before kidney perfusion was either obtained by direct bubble (groups 1, 3) or by membrane (group 2) oxygenation. Bubble oxygenation during minimum 15 min was as efficient as membrane oxygenation in achieving supraphysiological perfusate pO levels before kidney perfusion. Metabolic tissue analysis (i.e., lactate, succinate, ATP, NADH, and FMN) during and at the end of the preservation period demonstrated similar mitochondrial protection between all study groups. Short bubble and subsequent intermittent surface oxygenation of the perfusate of an HMP-kidney might be an effective and cheap preservation strategy to protect mitochondria, eliminating the need/costs of a membrane oxygenator and oxygen source during transport
Free surface flows emerging from beneath a semi-infinite plate with constant vorticity
The free surface flow past a semi-infinite horizontal plate in a finite-depth fluid is considered. It is assumed that the fluid is incompressible and inviscid and that the flow approaches a uniform shear flow downstream. Exact relations are derived using conservation of mass and momentum for the case where the downstream free surface is flat. The complete nonlinear problem is solved numerically using a boundary integral method and these waveless solutions are shown to exist only when the height of the plate above the bottom is greater than the height of the uniform shear flow. Interesting results are found for various values of the constant vorticity. Solutions with downstream surface waves are also considered, and nonlinear results of this type are compared with linear results found previously. These solutions can be used to model the flow near the stern of a (two-dimensional) ship
Record Maximum Oscillation Frequency in C-face Epitaxial Graphene Transistors
The maximum oscillation frequency (fmax) quantifies the practical upper bound
for useful circuit operation. We report here an fmax of 70 GHz in transistors
using epitaxial graphene grown on the C-face of SiC. This is a significant
improvement over Si-face epitaxial graphene used in the prior high frequency
transistor studies, exemplifying the superior electronics potential of C-face
epitaxial graphene. Careful transistor design using a high {\kappa} dielectric
T-gate and self-aligned contacts, further contributed to the record-breaking
fmax
A simple model for the evolution of disc galaxies: The Milky Way
A simple model for the evolution of disc galaxies is presented. We adopt
three numbers from observations of the Milky Way disc, the local surface mass
density, the stellar scale length (of the assumedly exponential disc) and the
amplitude of the (assumedly flat) rotation curve, and physically, the (local)
dynamical Kennicutt star formation prescription, standard chemical evolution
equations assuming and a model for spectral evolution of stellar populations.
We can determine the detailed evolution of the model with only the addition of
standard cosmological scalings with time of the dimensional parameters. A
surprising wealth of detailed specifications follows from this prescription
including the gaseous infall rate as a function of radius and time, the
distribution of stellar ages and metallicities with time and radius, surface
brightness profiles at different wavelengths, colours etc. At the solar
neighbourhood stars start to form ago at an increasing rate
peaking 4 billion years ago and then slowly declining in good agreement with
observations. The mean age of long lived stars at the solar neighbourhood is
about . The local surface density of the stars and gas are 35 and , respectively. The metallicity distribution of the stars at
the solar radius is narrow with a peak at .Both a
Salpeter IMF and a Chabrier IMF are consistent with observations. Comparisons
with the current and local fossil evidence provides support for the model which
can then be used to assess other local disc galaxies, the evolution of disc
galaxies in deep optical surveys and also for theoretical investigations such
as simulations of merging disc galaxies (abbreviated).Comment: acceppted for publication in MNRA
A global database for metacommunity ecology, integrating species, traits, environment and space
The use of functional information in the form of species traits plays an important role in explaining biodiversity patterns and responses to environmental changes. Although relationships between species composition, their traits, and the environment have been extensively studied on a case-by-case basis, results are variable, and it remains unclear how generalizable these relationships are across ecosystems, taxa and spatial scales. To address this gap, we collated 80 datasets from trait-based studies into a global database for metaCommunity Ecology: Species, Traits, Environment and Space; âCESTESâ. Each dataset includes four matrices: species community abundances or presences/absences across multiple sites, species trait information, environmental variables and spatial coordinates of the sampling sites. The CESTES database is a live database: it will be maintained and expanded in the future as new datasets become available. By its harmonized structure, and the diversity of ecosystem types, taxonomic groups, and spatial scales it covers, the CESTES database provides an important opportunity for synthetic trait-based research in community ecology
Fermenting Feminism
"Fermenting Feminism brings together artists whose work responds to what it means to bring fermentation and feminism into the same critical space. These are works that approach fermentation through intersectional and trans-inclusive feminist frameworks, and works that approach feminisms through the metaphor and material practice of fermentation. As both a metaphor and a physical process, fermentation embodies bioavailability and accessibility, preservation and transformation, inter-species symbiosis and coevolution, biodiversity and futurity, harm reduction and care." -- p. [1]
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