8,772 research outputs found
Tensile testing apparatus
An improved mechanical extensometer is described for use with a constant load creep test machine. The dead weight of the extensometer is counterbalanced by two pairs of weights connected through a pulley system and to rod extension and leading into the furnace where the test sample is undergoing elevated temperature (above 500 F.) tensile testing. Novel gripper surfaces, conical tip and flat surface are provided in each sampling engaging platens to reduce the grip pressure normally required for attachment of the extensometer to the specimen and reduce initial specimen bending normally associated with foil-gage metal testing
Evaluation of a hybrid, anisotropic, multilayered, quadrilateral finite element
A multilayered finite element with bending-extensional coupling is evaluated for: (1) buckling of general laminated plates; (2) thermal stresses of laminated plates cured at elevated temperatures; (3) displacements of a bimetallic beam; and (4) displacement and stresses of a single-cell box beam with warped cover panels. Also, displacements and stresses for flat and spherical orthotropic and anisotropic segments are compared with results from higher order plate and shell finite-element analyses
A First Comparison of SLOPE and Other LIGO Burst Event Trigger Generators
A number of different methods have been proposed to identify unanticipated
burst sources of gravitational waves in data arising from LIGO and other
gravitational wave detectors. When confronted with such a wide variety of
methods one is moved to ask if they are all necessary, i.e. given detector data
that is assumed to have no gravitational wave signals present, do they
generally identify the same events with the same efficiency, or do they each
'see' different things in the detector? Here we consider three different
methods, which have been used within the LIGO Scientific Collaboration as part
of its search for unanticipated gravitational wave bursts. We find that each of
these three different methods developed for identifying candidate gravitational
wave burst sources are, in fact, attuned to significantly different features in
detector data, suggesting that they may provide largely independent lists of
candidate gravitational wave burst events.Comment: 10 Pages, 5 Figures, Presented at the 10th Gravitational Wave Data
Analysis Workshop (GWDAW-10), 14-17 December 2005 at the University of Texas,
Brownsvill
Unexpected phase locking of magnetic fluctuations in the multi-k magnet USb
The spin waves in the multi-k antiferromagnet USb soften and become quasielastic well below the antiferromagnetic ordering temperature TN. This occurs without a magnetic or structural transition. It has been suggested that this change is in fact due to dephasing of the different multi-k components: a switch from 3-k to 1-k behavior. In this work, we use inelastic neutron scattering with tridirectional polarization analysis to probe the quasielastic magnetic excitations and reveal that the 3-k structure does not dephase. More surprisingly, the paramagnetic correlations also maintain the same clear phase correlations well above TN (up to at least 1.4TN)
Exhaustive Suzuki-Miyaura Reactions of Polyhalogenated Heteroarenes with Alkyl Boronic Pinacol Esters
A novel Suzuki-Miyaura protocol is described that enables the exhaustive alkylation of polychlorinated pyridines. This method facilitates a formal synthesis of normuscopyridine and the rapid assembly of a dumbbell shaped portion of a [2]rotaxane
Search for Gravitational Waves from Intermediate Mass Binary Black Holes
We present the results of a weakly modeled burst search for gravitational waves from mergers of non-spinning intermediate mass black holes (IMBH) in the total mass range 100-450 solar Mass and with the component mass ratios between 1:1 and 4:1. The search was conducted on data collected by the LIGO and Virgo detectors between November of 2005 and October of 2007. No plausible signals were observed by the search which constrains the astrophysical rates of the IMBH mergers as a function of the component masses. In the most efficiently detected bin centered on 88 + 88 solar Mass , for non-spinning sources, the rate density upper limit is 0.13 per Mpc(exp 3) per Myr at the 90% confidence level
A case of a single intracranial vertebral artery and cerebral infarct
The vertebral arteries are commonly affected by anatomical variation. This variation ranges from slight asymmetry in arterial diameter between the right and left sides to complete absence of a vertebral artery on one side. Asymmetry in diameter is a common observation, although complete absence of the artery is rare. Herein, we report on a 79-year-old male anatomical donor who, upon brain removal, was found to have a single intracranial vertebral artery which was the sole source of the basilar artery. During dissection of the neck, both right and left vertebral arteries were identified arising from the subclavian arteries. The vertebral arteries were dissected from the transverse foramina and followed into the skull. The right vertebral artery terminated by supplying the spinal cord, consistent with the distribution of the posterior spinal artery. Such vascular anomalies are clinically significant, as they may lead to abnormal patterns of sensory-motor deficiencies in stroke and are at risk of iatrogenic injury during surgical procedures
Raman study of the Verwey transition in Magnetite at high-pressure and low-temperature; effect of Al doping
We report high-pressure low-temperature Raman studies of the Verwey
transition in pure and Al-doped magnetite (Fe_3O_4). The low temperature phase
of magnetite displays a number of additional Raman modes that serve as
transition markers. These transition markers allow one to investigate the
effect of hydrostatic pressure on the Verwey transition temperature. Al-doped
magnetite Fe_2.8Al_0.2O_4 (TV=116.5K) displays a nearly linear decrease of the
transition temperature with an increase of pressure yielding dP/dT_V = -0.096
GPa/K. In contrast pure magnetite displays a significantly steeper slope of the
PT equilibrium line with dP/dT_V = -0.18 GPa/K. The slope of the PT equilibrium
lines is related to the changes of the molar entropy and molar volume at the
transition. We compare our spectroscopic data with that obtained from the
ambient pressure specific heat measurements and find a good agreement in the
optimally doped magnetite. Our data indicates that Al doping leads to a smaller
entropy change and larger volume expansion at the transition. Our data displays
the trends that are consistent with the mean field model of the transition that
assumes charge ordering in magnetite.Comment: 17 pages, 3 figure
Unconventional magnetic phase separation in -CoVO
We have explored the magnetism in the non-geometrically frustrated spin-chain
system -CoVO which possesses a complex magnetic exchange
network. Our neutron diffraction patterns at low temperatures (
= 6.6 K) are best described by a model in which two magnetic
phases coexist in a volume ratio 65(1) : 35(1), with each phase consisting of a
single spin modulation. This model fits previous studies and our observations
better than the model proposed by Lenertz in J. Phys. Chem. C 118,
13981 (2014), which consisted of one phase with two spin modulations. By
decreasing the temperature from , the minority phase of our
model undergoes an incommensurate-commensurate lock-in transition at =
5.6 K. Based on these results, we propose that phase separation is an
alternative approach for degeneracy-lifting in frustrated magnets
Hostility and cellular aging in men from the Whitehall II cohort.
Hostility is associated with a significantly increased risk of age-related disease and mortality, yet the pathophysiological mechanisms involved remain unclear. Here we investigated the hypothesis that hostility might impact health by promoting cellular aging
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