2,591 research outputs found
Some inconsistencies of the finite element method as applied to inelastic response
The inadequacy of a two noded beam-column element with a linear axial and a cubic transverse displacement field for inelastic analysis is demonstrated. For complete equilibrium satisfaction in the linear elastic range a three noded beam-column element is shown to be consistent. Next, the sensitivity of the inelastic response to numerical solutions of the inelastic response of a cantilever beam resulting from approximate integration of strain energy are brought out and finally, consequences of this on the nonlinear transient response of structures are considered
Ultracold Neutral Plasmas
Ultracold neutral plasmas, formed by photoionizing laser-cooled atoms near
the ionization threshold, have electron temperatures in the 1-1000 kelvin range
and ion temperatures from tens of millikelvin to a few kelvin. They represent a
new frontier in the study of neutral plasmas, which traditionally deals with
much hotter systems, but they also blur the boundaries of plasma, atomic,
condensed matter, and low temperature physics. Modelling these plasmas
challenges computational techniques and theories of non-equilibrium systems, so
the field has attracted great interest from the theoretical and computational
physics communities. By varying laser intensities and wavelengths it is
possible to accurately set the initial plasma density and energy, and
charged-particle-detection and optical diagnostics allow precise measurements
for comparison with theoretical predictions. Recent experiments using optical
probes demonstrated that ions in the plasma equilibrate in a strongly coupled
fluid phase. Strongly coupled plasmas, in which the electrical interaction
energy between charged particles exceeds the average kinetic energy, reverse
the traditional energy hierarchy underlying basic plasma concepts such as Debye
screening and hydrodynamics. Equilibration in this regime is of particular
interest because it involves the establishment of spatial correlations between
particles, and it connects to the physics of the interiors of gas-giant planets
and inertial confinement fusion devices.Comment: 89 pages, 54 image
Understanding Everyday Relationship Work: The Development of a Relationship Maintenance Scale
Relationship maintenance behaviors contribute to the longevity of intimate relationships, yet existing scales are limited. Available measurement tools are primarily constrained to the Relationship Maintenance Strategy Measure (RMSM) and its further revisions. Covering a number of domains, conceptual overlap with other aspects of an intimate relationship (e.g., household division of labor) may exist. Our cross-sectional exploratory study included participants from 60 countries (n=8,162) who completed an online survey. Participants were diverse in their relationship status, age, sexual orientation, and race/ethnicity. From their responses, we developed a parsimonious and brief measure of relationship maintenance (8 items) through exploratory and then confirmatory factor analyses. Results indicated that the Relationship Maintenance Scale (RMS) shows initial evidence of reliability and validity. The RMS may have utility in working with couples and families. Future research should seek to re-test its use with varied samples, such as couples seeking relationship support
Violence against Asians: When Is Racial Hate a Crime?
In this article we focus on the mass shootings of Asian women at Atlanta spas. After the perpetrator killed six Asian women, he told the police that he wanted to eliminate “all Asians” and spoke of the “temptation” of the massage parlors and spas. We ask at what point will these forms of anti-Asian violence first be acknowledged, and then seen as a clear and present danger? To answer these questions we trace the historical roots in US history, and domestic and foreign policies of such violence. We reflect on a history of imperial politics, the means and methods of writing global power, including armed conflicts with and in Japan, Korea, and Vietnam, and the more recent US-China rivalry and antagonism. Second, we argue that divisions and hierarchizations as articulated through these policies are political technologies of control of subjects and territories which are bounded for capture and for experimentation toward the reproduction of a global order of the West and the Rest. In sum, we suggest that the asymmetrical and unequal sexualized landscapes and Othering that produce such violences ought to be critiqued, disrupted, and publicly challenged
Bose-Einstein Condensation of Sr Through Sympathetic Cooling with Sr
We report Bose-Einstein condensation of Sr, which has a small,
negative s-wave scattering length (\,). We overcome the poor
evaporative cooling characteristics of this isotope by sympathetic cooling with
Sr atoms. Sr is effective in this role in spite of the fact that
it is a fermion because of the large ground state degeneracy arising from a
nuclear spin of , which reduces the impact of Pauli blocking of
collisions. We observe a limited number of atoms in the condensate
() that is consistent with the value of and the
optical dipole trap parameters.Comment: 4 pages, 4 figure
Runaway evaporation for optically dressed atoms
Forced evaporative cooling in a far-off-resonance optical dipole trap is
proved to be an efficient method to produce fermionic- or bosonic-degenerated
gases. However in most of the experiences, the reduction of the potential
height occurs with a diminution of the collision elastic rate. Taking advantage
of a long-living excited state, like in two-electron atoms, I propose a new
scheme, based on an optical knife, where the forced evaporation can be driven
independently of the trap confinement. In this context, the runaway regime
might be achieved leading to a substantial improvement of the cooling
efficiency. The comparison with the different methods for forced evaporation is
discussed in the presence or not of three-body recombination losses
World Religions and Spirituality Project: Emerging Church
Description of the Emerging Church for the World Religion and Spirituality Project
Ultracold Neutral Plasmas
Ultracold neutral plasmas are formed by photoionizing laser-cooled atoms near
the ionization threshold. Through the application of atomic physics techniques
and diagnostics, these experiments stretch the boundaries of traditional
neutral plasma physics. The electron temperature in these plasmas ranges from
1-1000 K and the ion temperature is around 1 K. The density can approach
cm. Fundamental interest stems from the possibility of
creating strongly-coupled plasmas, but recombination, collective modes, and
thermalization in these systems have also been studied. Optical absorption
images of a strontium plasma, using the Sr
transition at 422 nm, depict the density profile of the plasma, and probe
kinetics on a 50 ns time-scale. The Doppler-broadened ion absorption spectrum
measures the ion velocity distribution, which gives an accurate measure of the
ion dynamics in the first microsecond after photoionization.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004,
Nice (France
Temporal discrimination: Mechanisms and relevance to adult-onset dystonia
Temporal discrimination is the ability to determine that two sequential sensory stimuli are separated in time. For any individual, the temporal discrimination threshold (TDT) is the minimum interval at which paired sequential stimuli are perceived as being asynchronous; this can be assessed, with high test-retest and inter-rater reliability, using a simple psychophysical test. Temporal discrimination is disordered in a number of basal ganglia diseases including adult-onset dystonia, of which the two most common phenotypes are cervical dystonia and blepharospasm. The causes of adult-onset focal dystonia are unknown; genetic, epigenetic, and environmental factors are relevant. Abnormal TDTs in adult-onset dystonia are associated with structural and neurophysiological changes considered to reflect defective inhibitory interneuronal processing within a network which includes the superior colliculus, basal ganglia, and primary somatosensory cortex. It is hypothesized that abnormal temporal discrimination is a mediational endophenotype and, when present in unaffected relatives of patients with adult-onset dystonia, indicates non-manifesting gene carriage. Using the mediational endophenotype concept, etiological factors in adult-onset dystonia may be examined including (i) the role of environmental exposures in disease penetrance and expression; (ii) sexual dimorphism in sex ratios at age of onset; (iii) the pathogenesis of non-motor symptoms of adult-onset dystonia; and (iv) subcortical mechanisms in disease pathogenesis
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