1,102 research outputs found
Lunar resource evaluation and mine site selection
Two scenarios in this evaluation of lunar mineral resources and the selection of possible mining and processing sites are considered. The first scenario assumes that no new surface or near-surface data will be available before site selection (presumably one of the Apollo sites). The second scenario assumes that additional surface geology data will have been obtained by a lunar orbiter mission, an unmanned sample return mission (or missions), and followup manned missions. Regardless of the scenario, once a potentially favorable mine site has been identified, a minimum amount of fundamental data is needed to assess the resources at that site and to evaluate its suitability for mining and downstream processing. Since much of the required data depends on the target mineral(s), information on the resource, its beneficiation, and the refining, smelting, and fabricating processes must be factored into the evaluation. The annual capacity and producing lifetime of the mine and its associated processing plant must be estimated before the resource reserves can be assessed. The available market for the product largely determines the capacity and lifetime of the mine. The Apollo 17 site is described as a possible mining site. The use of new sites is briefly addressed
Black Hole Mergers in Galactic Nuclei Induced by the Eccentric Kozai-Lidov Effect
Nuclear star clusters around massive black holes are expected to be abundant
in stellar mass black holes and black hole binaries. These binaries form a
hierarchical triple system with the massive black hole at the center.
Gravitational perturbations from the massive black hole can cause high
eccentricity excitation. During this process, the eccentricity may approach
unity, and the pericenter distance may become sufficiently small that
gravitational wave emission drives the binary to merge. In this paper, we
consider a simple proof of concept and explore the effect of the eccentric
Kozai-Lidov mechanism for unequal mass binaries. We perform a set of Monte
Carlo simulations on BH-BH binaries in galactic nuclei with quadrupole and
octupole-level secular perturbations, general relativistic precession, and
gravitational wave emission. For a nominal number of steady-state BH-BH
binaries, our model gives a total merger rate ,
depending on the assumed density profile. Thus, our model potentially competes
with other dynamical mechanisms, such as the dynamical formations and mergers
of BH binaries in globular clusters or dense nuclear clusters without a massive
black hole. We provide predictions for the distributions of these LIGO sources
in galactic nuclei.Comment: 10 pages, 12 figures, accepted to Ap
Effects of strain on the electronic structure of VO_2
We present cluster-DMFT (CTQMC) calculations based on a downfolded
tight-binding model in order to study the electronic structure of vanadium
dioxide (VO_2) both in the low-temperature (M_1) and high-temperature (rutile)
phases. Motivated by the recent efforts directed towards tuning the physical
properties of VO_2 by depositing films on different supporting surfaces of
different orientations we performed calculations for different geometries for
both phases. In order to investigate the effects of the different growing
geometries we applied both contraction and expansion for the lattice parameter
along the rutile c-axis in the 3-dimensional translationally invariant systems
miming the real situation. Our main focus is to identify the mechanisms
governing the formation of the gap characterizing the M_1 phase and its
dependence on strain. We found that the increase of the band-width with
compression along the axis corresponding to the rutile c-axis is more important
than the Peierls bonding-antibonding splitting
Can Virialization Shocks be Detected Around Galaxy Clusters Through the Sunyaev-Zel'dovich Effect?
In cosmological structure formation models, massive non-linear objects in the
process of formation, such as galaxy clusters, are surrounded by large-scale
shocks at or around the expected virial radius. Direct observational evidence
for such virial shocks is currently lacking, but we show here that their
presence can be inferred from future, high resolution, high-sensitivity
observations of the Sunyaev-Zel'dovich (SZ) effect in galaxy clusters. We study
the detectability of virial shocks in mock SZ maps, using simple models of
cluster structure (gas density and temperature distributions) and noise
(background and foreground galaxy clusters projected along the line of sight,
as well as the cosmic microwave background anisotropies). We find that at an
angular resolution of 2'' and sensitivity of 10 micro K, expected to be reached
at ~ 100 GHz frequencies in a ~ 20 hr integration with the forthcoming ALMA
instrument, virial shocks associated with massive M ~ 10^15 M_Sun clusters will
stand out from the noise, and can be detected at high significance. More
generally, our results imply that the projected SZ surface brightness profile
in future, high-resolution experiments will provide sensitive constraints on
the density profile of cluster gas.Comment: 15 pages, submitted to Ap
Wide-Range Optical CMOS-Based Diagnostics
Colorimetric, chemiluminescence and refractive index based diagnostics are some of the most important sensing techniques in biomedical science and clinical medicine. Conventionally laboratories and medical clinics rely on bulky and dedicated equipment for each diagnostic technique independently. In this paper, we present CMOS sensor based solutions, comprising a single photon avalanche detector array and photodiode array. The CMOS platform offers low cost integration and wide range of light-based diagnostic techniques, leading to development of point-of-care devices
Distortion of Gravitational-Wave Packets Due to their Self-Gravity
When a source emits a gravity-wave (GW) pulse over a short period of time,
the leading edge of the GW signal is redshifted more than the inner boundary of
the pulse. The GW pulse is distorted by the gravitational effect of the
self-energy residing in between these shells. We illustrate this distortion for
GW pulses from the final plunge of black hole (BH) binaries, leading to the
evolution of the GW profile as a function of the radial distance from the
source. The distortion depends on the total GW energy released and the duration
of the emission, scaled by the total binary mass, M. The effect should be
relevant in finite box simulations where the waveforms are extracted within a
radius of <~ 100M. For characteristic emission parameters at the final plunge
between binary BHs of arbitrary spins, this effect could distort the simulated
GW templates for LIGO and LISA by a fraction of 0.001. Accounting for the wave
distortion would significantly decrease the waveform extraction errors in
numerical simulations.Comment: accepted for publication in Physical Review
Retinal Adaptation to Object Motion
Due to fixational eye movements, the image on the retina is always in motion, even when one views a stationary scene. When an object moves within the scene, the corresponding patch of retina experiences a different motion trajectory than the surrounding region. Certain retinal ganglion cells respond selectively to this condition, when the motion in the cell's receptive field center is different from that in the surround. Here we show that this response is strongest at the very onset of differential motion, followed by gradual adaptation with a time course of several seconds. Different subregions of a ganglion cell's receptive field can adapt independently. The circuitry responsible for differential motion adaptation lies in the inner retina. Several candidate mechanisms were tested, and the adaptation most likely results from synaptic depression at the synapse from bipolar to ganglion cell. Similar circuit mechanisms may act more generally to emphasize novel features of a visual stimulus
Agmatine and Agmatine Analogs in the Treatment of Epilepsy, Seizure, and Electroconvulsive Disorders
Pharmaceutical preparations containing of agmatine, congeners, analogs or derivatives thereof for use in preventing or treating epilepsy, seizures and other electroconvulsive disorders are provided. Embodiments include administering an effective amount of agmatine, an agmatine analog or a pharmaceutically acceptable salt thereof to a human subject in need of treatment or prevention of epilepsy, seizure or other electroconvulsive disorder to treat, reduce, or prevent the disorder in the subject
Merger rates of intermediate-mass black hole binaries in nuclear star clusters
Repeated mergers of stellar-mass black holes (BHs) in dense star clusters can
produce intermediate-mass black holes (IMBHs). In particular, nuclear star
clusters at the centers of galaxies have deep enough potential wells to retain
most of the BH merger products, in spite of the significant recoil kicks due to
anisotropic emission of gravitational radiation. These events can be detected
in gravitational waves (GWs), which represent an unprecedented opportunity to
reveal IMBHs. In this paper, we analyze the statistical results of a wide range
of numerical simulations, which encompass different cluster metallicities,
initial BH seed masses, and initial BH spins, and we compute the merger rate of
IMBH binaries. We find that merger rates are in the range
-\,Gpc\,yr depending on IMBH masses. We also compute
the number of multi-band detections in ground-based and space-based
observatories. Our model predicts that a few merger events per year should be
detectable with LISA, DECIGO, ET, and LIGO for IMBHs with masses \lesssim
1000\msun, and a few tens of merger events per year with DECIGO, ET, and LIGO
only.Comment: 11 pages, 6 figure
Compounds of Use in the Treatment of Epilepsy, Seizure, and Electroconvulsive Disorders
The present invention provides pharmaceutical preparations and the uses thereof for preventing and/or treating seizures and other electroconvulsive disorders by administering a pharmaceutically effective amount of a therapeutic compound . . .
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