949 research outputs found
Type IIA Moduli Stabilization
We demonstrate that flux compactifications of type IIA string theory can
classically stabilize all geometric moduli. For a particular orientifold
background, we explicitly construct an infinite family of supersymmetric vacua
with all moduli stabilized at arbitrarily large volume, weak coupling, and
small negative cosmological constant. We obtain these solutions from both
ten-dimensional and four-dimensional perspectives. For more general
backgrounds, we study the equations for supersymmetric vacua coming from the
effective superpotential and show that all geometric moduli can be stabilized
by fluxes. We comment on the resulting picture of statistics on the landscape
of vacua.Comment: 48 pages, 2 figures, LaTeX. v2: references added. v3: minor comments
& references adde
A Passive Monitoring System in Assisted Living Facilities: 12-Month Comparative Study
The GE QuietCareÂź passive monitoring system uses advanced motion sensor technology that learns the daily living patterns of senior community residents and sends alerts when certain out-of-the-ordinary events occur. This study compared falls, hospitalizations, care level changes, and resident attrition between two similar assisted living facilities where one facility adopted the QuietCareÂź monitoring system and the other did not over a 12-month period. Average falls per week were significantly lower in the QuietCareÂź facility than the control facility. There was also a trend toward fewer weekly hospitalizations in the QuietCareÂź facility. There was higher resident retention at the QuietCareÂź facility. This study provides evidence of direct benefits to both the resident and the facility for the use of QuietCareÂź. There was a significant reduction in the number of falls, as well as a general facility performance improvement measured by care level consistency and higher resident retention rates
Aluminium substitution induced superstructures in Mg1-xAlxB2 (x = 0.0 to 0.50): An X-ray diffraction study
The physical property characterization of Al doped Mg1-xAlxB2 system with x =
0.0 to 0.50 is reported. The results related to phase formation, structural
transition, resistivity R(T) and magnetization M(T) measurements are discussed
in detail. It is shown that the addition of electrons to MgB2 through Al
results in loss of superconductivity. Also seen is a structural transition
associated with the collapse of boron layers reflected by the continuous
decrease in the c parameter. The main emphasis in this paper is on slow scan
X-ray diffraction (XRD) results, which confirm the existence of a
superstructure along the c-direction for the x = 0.50 sample. The appearance of
some additional peaks, viz. [103], [004], [104] and [112], results in doubling
of the lattice parameter along the c-axis. This possibly indicates the
alternative ordering of Al and Mg in MgAlB4 separated by hexagonal boron layers
but still maintaining the same hexagonal AlB2 type structure.Comment: 17 Pages Text + Figs. To appear in Physica
Composição corporal de cĂĄlcio e fĂłsforo do Ăștero gestante e da glĂąndula mamĂĄria de ovelhas Santa InĂȘs
Shear-induced dynamics of polymeric globules at adsorbing homogeneous and inhomogeneous surfaces
A Measurement of Psi(2S) Resonance Parameters
Cross sections for e+e- to hadons, pi+pi- J/Psi, and mu+mu- have been
measured in the vicinity of the Psi(2S) resonance using the BESII detector
operated at the BEPC. The Psi(2S) total width; partial widths to hadrons,
pi+pi- J/Psi, muons; and corresponding branching fractions have been determined
to be Gamma(total)= (264+-27) keV; Gamma(hadron)= (258+-26) keV, Gamma(mu)=
(2.44+-0.21) keV, and Gamma(pi+pi- J/Psi)= (85+-8.7) keV; and Br(hadron)=
(97.79+-0.15)%, Br(pi+pi- J/Psi)= (32+-1.4)%, Br(mu)= (0.93+-0.08)%,
respectively.Comment: 8 pages, 6 figure
The composition of the protosolar disk and the formation conditions for comets
Conditions in the protosolar nebula have left their mark in the composition
of cometary volatiles, thought to be some of the most pristine material in the
solar system. Cometary compositions represent the end point of processing that
began in the parent molecular cloud core and continued through the collapse of
that core to form the protosun and the solar nebula, and finally during the
evolution of the solar nebula itself as the cometary bodies were accreting.
Disentangling the effects of the various epochs on the final composition of a
comet is complicated. But comets are not the only source of information about
the solar nebula. Protostellar disks around young stars similar to the protosun
provide a way of investigating the evolution of disks similar to the solar
nebula while they are in the process of evolving to form their own solar
systems. In this way we can learn about the physical and chemical conditions
under which comets formed, and about the types of dynamical processing that
shaped the solar system we see today.
This paper summarizes some recent contributions to our understanding of both
cometary volatiles and the composition, structure and evolution of protostellar
disks.Comment: To appear in Space Science Reviews. The final publication is
available at Springer via http://dx.doi.org/10.1007/s11214-015-0167-
The state of the Martian climate
60°N was +2.0°C, relative to the 1981â2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes
Exotic state photoproduction
It is shown that the list of unusual mesons planned for a careful study in
photoproduction can be extended by the exotic states with which should be looked for in the decay
channels in the reactions and . The full classification of the states by their
quantum numbers is presented. A simple model for the spin structure of the , , and reaction amplitudes is formulated and the tentative estimates of the
corresponding cross sections at the incident photon energy
GeV are obtained: b, b, b, and b. The problem of the
signal extraction from the natural background due to the other production channels is discussed. In particular the estimates are
presented for the , , and reaction cross sections.
Our main conclusion is that the search for the exotic
states is quite feasible at JEFLAB facility. The expected yield of the events in a 30-day run at the 100% detection
efficiency approximates events.Comment: 19 pages, revtex, 1 figure in postscipt, some comments and references
added, a few minor typos corrected, to be published in Phys. Rev.
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