1,125 research outputs found
Properties of protective oxide scales containing cerium on Incoloy 800H in oxidizing and sulfidizing environments. I. Constant-extension-rate study of mechanical properties
Space partitioning by symbiotic shrimp species cohabitating in the mushroom coral Heliofungia actiniformis at Semporna, eastern Sabah
Multi-particle effects in non-equilibrium electron tunnelling and field emission
We investigate energy resolved electric current from various correlated host
materials under out-of-equilibrium conditions. We find that, due to a combined
effect of electron-electron interactions, non-equilibrium and multi-particle
tunnelling, the energy resolved current is finite even above the Fermi edge of
the host material. In most cases, the current density possesses a singularity
at the Fermi level revealing novel manifestations of correlation effects in
electron tunnelling. By means of the Keldysh non-equilibrium technique, the
current density is calculated for one-dimensional interacting electron systems
and for two-dimensional systems, both in the pure limit and in the presence of
disorder. We then specialise to the field emission and provide a comprehensive
theoretical study of this effect in carbon nanotubes.Comment: 22 pages, 8 figures (eps files
Search for the electric dipole excitations to the multiplet in Sn
The odd-mass Sn nucleus was investigated in nuclear resonance
fluorescence experiments up to an endpoint energy of the incident photon
spectrum of 4.1 MeV at the bremsstrahlung facility of the Stuttgart University.
More than 50 mainly hitherto unknown levels were found. From the measurement of
the scattering cross sections model independent absolute electric dipole
excitation strengths were extracted. The measured angular distributions
suggested the spins of 11 excited levels. Quasi-particle phonon model
calculations including a complete configuration space were performed for the
first time for a heavy odd-mass spherical nucleus. These calculations give a
clear insight in the fragmentation and distribution of the , , and
excitation strength in the low energy region. It is proven that the
component of the two-phonon quintuplet built on
top of the ground state is strongly fragmented. The theoretical
calculations are consistent with the experimental data.Comment: 10 pages, 5 figure
Observation of isotonic symmetry for enhanced quadrupole collectivity in neutron-rich 62,64,66Fe isotopes at N=40
The transition rates for the 2_{1}^{+} states in 62,64,66Fe were studied
using the Recoil Distance Doppler-Shift technique applied to projectile Coulomb
excitation reactions. The deduced E2 strengths illustrate the enhanced
collectivity of the neutron-rich Fe isotopes up to N=40. The results are
interpreted by the generalized concept of valence proton symmetry which
describes the evolution of nuclear structure around N=40 as governed by the
number of valence protons with respect to Z~30. The deformation suggested by
the experimental data is reproduced by state-of-the-art shell calculations with
a new effective interaction developed for the fpgd valence space.Comment: 4 pages, 2 figure
Synchronized turbo apoptosis induced by cold-shock
In our research on the role of apoptosis in the pathogenesis of the autoimmune disease systemic lupus erythematosus (SLE), we aim to evaluate the effects of early and late apoptotic cells and blebs on antigen presenting cells. This requires the in vitro generation of sufficiently large and homogeneous populations of early and late apoptotic cells. Here, we present a quick method encountered by serendipity that results in highly reproducible synchronized homogeneous apoptotic cell populations. In brief, granulocytic 32Dcl3 cells are incubated on ice for 2 h and subsequently rewarmed at 37°C. After 30–90 min at 37°C more than 80–90% of the cells become early apoptotic (Annexin V positive/propidium iodide negative). After 24 h of rewarming at 37°C 98% of the cells were late apoptotic (secondary necrotic; Annexin V positive/propidium iodide positive). Cells already formed apoptotic blebs at their cell surface after approximately 20 min at 37°C. Inter-nucleosomal chromatin cleavage and caspase activation were other characteristics of this cold-shock-induced process of apoptosis. Consequently, apoptosis could be inhibited by a caspase inhibitor. Finally, SLE-derived anti-chromatin autoantibodies showed a high affinity for apoptotic blebs generated by cold-shock. Overall, cold-shock induced apoptosis is achieved without the addition of toxic compounds or antibodies, and quickly leads to synchronized homogeneous apoptotic cell populations, which can be applied for various research questions addressing apoptosis
Parents' underestimation of their child's weight status. Moderating factors and change over time: A cross-sectional study
BACKGROUND: Parents' underestimation of their child's weight status can hinder active participation in overweight prevention programs. We examined the level of agreement between the parents' perception of their child's weight status and the child's actual weight status, moderating factors, and change over time. METHODS: This cross-sectional study used data collected in 2009 (n = 8105), 2013 (n = 8844) and 2017 (n = 11,022) from a community-based survey conducted among parents of children age 2-12 years in the Netherlands. Parents classified their perception of their child's weight status on a 5-point Likert scale. In 2009 and 2013, the child's BMI was calculated from self-reported data by parents. The level of agreement between the parent's perception of the weight status and the actual weight status was examined using Cohen's kappa. The role of demographic factors on parents' perception were examined using logistic regression. RESULTS: In 2009, 2013 and 2017, 6%, 6% and 5% of the parents, respectively, classified their child as heavy/extremely heavy. In 2009 and 2013, 64.7% and 61.0% of parents, respectively, underestimated the weight status of their overweight child. This was even higher among parents of obese children. Overall, the agreement between the parents' perception and the actual weight status improved from 2009 (kappa = 0.38) to 2013 (kappa = 0.43) (p<0.05), but remained unsatisfactory. The parents' underestimation of their child's overweight/obesity status was associated with the child's age in 2009 and 2013 (2-7 years; OR: 0.18), the child's gender in 2009 (male; OR: 0.55), and the parents' education level in 2009 (middle and high education; OR: 0.56 and 0.44 respectively). CONCLUSIONS: Parents' underestimation of their child's weight status remains alarmingly high, particularly among parents of young, obese children. This underestimation is a barrier to preventing childhood overweight/obesity. Healthcare professionals should take this underestimation into consideration and should actively encourage parents to take steps to prevent overweight/obesity in their children
Lifetime determination of excited states in Cd-106
Two separate experiments using the Differential Decay Curve Method have been performed to extract mean lifetimes of excited states in 106 Cd. The inedium-spin states of interest were populated by the Mo-98(C-12, 4n) Cd-106 reaction performed at the Wright Nuclear Structure Lab., Yale University. From this experiment, two isomeric state mean lifetimes have been deduced. The low-lying states were populated by the Mo-96(C-13, 3n)Cd-106 reaction performed at the Institut fur Kernphysik, Universitat zu Koln. The mean lifetime of the I-pi = 2(1)(+) state was deduced, tentatively, as 16.4(9) ps. This value differs from the previously accepted literature value from Coulomb excitation of 10.43(9) ps
Strong fragmentation of low-energy electromagnetic excitation strength in Sn
Results of nuclear resonance fluorescence experiments on Sn are
reported. More than 50 transitions with MeV were
detected indicating a strong fragmentation of the electromagnetic excitation
strength. For the first time microscopic calculations making use of a complete
configuration space for low-lying states are performed in heavy odd-mass
spherical nuclei. The theoretical predictions are in good agreement with the
data. It is concluded that although the E1 transitions are the strongest ones
also M1 and E2 decays contribute substantially to the observed spectra. In
contrast to the neighboring even Sn, in Sn the
component of the two-phonon quintuplet built on top of
the 1/2 ground state is proved to be strongly fragmented.Comment: 4 pages, 3 figure
Are we overestimating the niche? Removing marginal localities helps ecological niche models detect environmental barriers
Correlative ecological niche models (ENMs) estimate species niches using occurrence records and environmental data. These tools are valuable to the field of biogeography, where they are commonly used to infer potential connectivity among populations. However, a recent study showed that when locally relevant environmental data are not available, records from patches of suitable habitat protruding into otherwise unsuitable regions (e.g., gallery forests within dry areas) can lead to overestimations of species niches and their potential distributions. Here, we test whether this issue obfuscates detection of an obvious environmental barrier existing in northern Venezuela – that of the hot and xeric lowlands separating the Penınsula de Paraguana from mainland South America. These conditions most likely promote isolation between mainland and peninsular populations of three rodent lineages occurring in mesic habitat in this region. For each lineage, we calibrated optimally parameterized ENMs using mainland records only, and leveraged existing habitat descriptions to assess whether those assigned low suitability values corresponded to instances where the species was collected within locally mesic conditions amidst otherwise hot dry areas. When this was the case, we built an additional model excluding these records. We projected both models onto the peninsula and assessed whether they differed in their ability to detect the environmental barrier. For the two lineages in which we detected such problematic records, only the models built excluding them detected the barrier, while providing additional insights regarding peninsular populations. Overall, the study reveals how a simple procedure like the one applied here can deal with records problematic for ENMs, leading to better predictions regarding the potential effects of the environment on lineage divergence
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