352 research outputs found
Experimental Measurements of Binder Wave Speeds using Wavenumber Decomposition
Prior work has provided few wave speed measurements for the binder materials commonly used with plastic- bonded energetics. Furthermore, those measurements that have been reported are largely based upon rudimentary, \u27pitch and catch\u27 methodologies, which involve sending a pulse from one transducer to another transducer at a set distance apart and measuring the time of flight. Given this, a more rigorous method for determining longitudinal and shear wave speeds in this important class of materials was desired. In this work, material wave speeds are recovered by measuring the vibrational response of a 2D line across the surface of a beam in response to a mechanical excitation and analyzing the data in the frequency-wavenumber domain
The Development and Validation of a Mental Toughness Scale for Adolescents
The present study examined the validity of a newly developed instrument, the Mental Toughness Scale for Adolescents (MTS-A), which examines the attributes of challenge, commitment, confidence (abilities and interpersonal) and control (life and emotion). The six factor model was supporting using Exploratory Factor Analysis (EFA, n = 373) and Confirmatory Factor Analysis (CFA, n = 372). In addition, the mental toughness attributes correlated with adolescents’ academic motivation and engagement (n = 439), well-being (depression and anxiety) (n = 279) and test anxiety (n = 279), indicating relations with a number of affective, cognitive and behavioural dispositions, and demonstrating relevance in education and potentially mental health contexts
A new type 2 copper cysteinate azurin: Involvement of an engineered exposed cysteine in copper binding trough internal rearrangement
The double mutant H117G/N42C azurin exhibits tetragonal type 2 copper site characteristics with Cys(42) as one of the copper ligands as concluded from spectroscopic evidence (UV-visible, EPR, and resonance Raman). Analysis of the kinetics of copper uptake by the apoprotein by means of stopped flow spectroscopy suggests that the solvent-exposed CyS42 assists in binding the metal ion and carrying it over to the active site where it becomes coordinated by, among others, a second cysteine, Cys(112). A structure is proposed in which the loop from residue 36 to 47 has rearranged to form a tetragonal type 2 copper site with Cys(42) as one of the ligands. The process of copper uptake as observed for the double mutant may be relevant for a better understanding of the way copper chaperones accept and transfer metal ions in the living cell.Macromolecular Biochemistr
The Moderating Effect of Mental Toughness: Perception of Risk and Belief in the Paranormal
This research demonstrates that higher levels of mental toughness provide cognitive-perceptual processing advantages when evaluating risk. No previous research, however, has examined mental toughness in relation to perception of risk and paranormal belief (a variable associated with distorted perception of causality and elevated levels of perceived risk). Accordingly, the present paper investigated relationships between these factors. A sample of 174 participants completed self-report measures assessing mental toughness, general perception of risk, and paranormal belief. Responses were analyzed via correlations and moderation analyses. Results revealed that mental toughness correlated negatively with perception of risk and paranormal belief, whereas paranormal belief correlated positively with perception of risk. For the moderation effects, simple slopes analyses indicated that high levels of MT and subfactors of commitment and confidence reduced the strength of association between paranormal belief and perceived risk. Therefore, MT potentially acts as a protective factor among individuals who believe in the paranormal, reducing the tendency to perceive elevated levels of risk
Galaxy Clusters Selected with the Sunyaev-Zel'dovich Effect from 2008 South Pole Telescope Observations
We present a detection-significance-limited catalog of 21 Sunyaev-Zel'dovich
selected galaxy clusters. These clusters, along with 1 unconfirmed candidate,
were identified in 178 deg^2 of sky surveyed in 2008 by the South Pole
Telescope to a depth of 18 uK-arcmin at 150 GHz. Optical imaging from the
Blanco Cosmology Survey (BCS) and Magellan telescopes provided photometric (and
in some cases spectroscopic) redshift estimates, with catalog redshifts ranging
from z=0.15 to z>1, with a median z = 0.74. Of the 21 confirmed galaxy
clusters, three were previously identified as Abell clusters, three were
presented as SPT discoveries in Staniszewski et al, 2009, and three were first
identified in a recent analysis of BCS data by Menanteau et al, 2010; the
remaining 12 clusters are presented for the first time in this work. Simulated
observations of the SPT fields predict the sample to be nearly 100% complete
above a mass threshold of M_200 ~ 5x10^14 M_sun/h at z = 0.6. This completeness
threshold pushes to lower mass with increasing redshift, dropping to ~4x10^14
M_sun/h at z=1. The size and redshift distribution of this catalog are in good
agreement with expectations based on our current understanding of galaxy
clusters and cosmology. In combination with other cosmological probes, we use
the cluster catalog to improve estimates of cosmological parameters. Assuming a
standard spatially flat wCDM cosmological model, the addition of our catalog to
the WMAP 7-year analysis yields sigma_8 = 0.81 +- 0.09 and w = -1.07 +- 0.29, a
~50% improvement in precision on both parameters over WMAP7 alone.Comment: 19 pages, 9 figures, 4 appendice
Measurement of neutral current e+/-p cross sections at high Bjorken x with the ZEUS detector
The neutral current e+/-p cross section has been measured up to values of
Bjorken x of approximately 1 with the ZEUS detector at HERA using an integrated
luminosity of 187 inv. pb of e-p and 142 inv. pb of e+p collisions at sqrt(s) =
318GeV. Differential cross sections in x and Q2, the exchanged boson
virtuality, are presented for Q2 geq 725GeV2. An improved reconstruction method
and greatly increased amount of data allows a finer binning in the high-x
region of the neutral current cross section and leads to a measurement with
much improved precision compared to a similar earlier analysis. The
measurements are compared to Standard Model expectations based on a variety of
recent parton distribution functions.Comment: 39 pages, 9 figure
Combined QCD and electroweak analysis of HERA data
A simultaneous fit of parton distribution functions (PDFs) and electroweak
parameters to HERA data on deep inelastic scattering is presented. The input
data are the neutral current and charged current inclusive cross sections which
were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In
addition, the polarisation of the electron beam was taken into account for the
ZEUS data recorded between 2004 and 2007. Results on the vector and
axial-vector couplings of the Z boson to u- and d-type quarks, on the value of
the electroweak mixing angle and the mass of the W boson are presented. The
values obtained for the electroweak parameters are in agreement with Standard
Model predictions.Comment: 32 pages, 10 figures, accepted by Phys. Rev. D. Small corrections
from proofing process and small change to Fig. 12 and Table
Search for a narrow baryonic state decaying to and in deep inelastic scattering at HERA
A search for a narrow baryonic state in the and
system has been performed in collisions at HERA with the ZEUS detector
using an integrated luminosity of 358 pb taken in 2003-2007. The search
was performed with deep inelastic scattering events at an centre-of-mass
energy of 318 GeV for exchanged photon virtuality, , between 20 and 100
. Contrary to evidence presented for such a state around 1.52
GeV in a previous ZEUS analysis using a sample of 121 pb taken in
1996-2000, no resonance peak was found in the invariant-mass
distribution in the range 1.45-1.7 GeV. Upper limits on the production cross
section are set.Comment: 16 pages, 4 figures, accepted by Phys. Lett. B. Minor changes from
journal reviewing process, including a small correction to figure
Determinants of exocrine pancreatic function as measured by fecal elastase-1 concentrations (FEC) in patients with diabetes mellitus
<p>Abstract</p> <p>Objective</p> <p>Recently it has been shown that there is not only endocrine insufficiency in diabetic patients, but a frequent co-morbidity of both, the endocrine and exocrine pancreas. The present study was performed to further analyse the determinants of exocrine pancreatic function in patients with diabetes mellitus.</p> <p>Methods</p> <p>The records of 1992 patients with diabetes mellitus who had been treated in our hospital during a 2-year period were re-evaluated. Defined parameters were documented in standardized data sheets. Records were further checked for the results of imaging procedures of the pancreas. In 307 patients FEC had been performed and documented. Only these patients were included in further evaluation.</p> <p>Results</p> <p>FEC was inversely correlated with diabetes duration and HbA1c-levels but not with age. C-peptide levels correlated positively with FEC. BMI and FEC were also significantly correlated. There was no correlation between diabetes therapy and exocrine pancreatic function as there was no correlation with any concomitant medication. The presence of diabetes-associated antibodies was not related to FEC. According to the documented data 38 were classified as type-1 diabetes (12.4%), 167 as type-2 (54.4%), and 88 patients met the diagnostic criteria of type-3 (28.7%). Fourteen patients could not be classified because of lacking information (4.6%).</p> <p>Conclusions</p> <p>Exocrine insufficiency might be explained as a complication of diabetes mellitus. However, it is more likely that type-3 diabetes is much more frequent than previously believed. Consequently the evaluation of exocrine function and morphology should be included into the clinical workup of any diabetic patient at least at the time of manifestation.</p
The concept of RNA-assisted protein folding: the role of tRNA
We suggest that tRNA actively participates in the transfer of 3D information from mRNA to peptides - in addition to its well-known, "classical" role of translating the 3-letter RNA codes into the one letter protein code. The tRNA molecule displays a series of thermodynamically favored configurations during translation, a movement which places the codon and coded amino acids in proximity to each other and make physical contact between some amino acids and their codons possible. This specific codon-amino acid interaction of some selected amino acids is necessary for the transfer of spatial information from mRNA to coded proteins, and is known as RNA-assisted protein folding
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