6,374 research outputs found
Geothermal studies - Yellowstone National Park /test site 11/, Wyoming
Summary report of diamond drilling in thermal areas of Yellowstone National Park, and method for determining heat flow in thermal area
Statistical Searches for Microlensing Events in Large, Non-Uniformly Sampled Time-Domain Surveys: A Test Using Palomar Transient Factory Data
Many photometric time-domain surveys are driven by specific goals, such as
searches for supernovae or transiting exoplanets, which set the cadence with
which fields are re-imaged. In the case of the Palomar Transient Factory (PTF),
several sub-surveys are conducted in parallel, leading to non-uniform sampling
over its footprint. While the median PTF field has been imaged 40 times in \textit{R}-band,
have been observed 100 times. We use PTF data to
study the trade-off between searching for microlensing events in a survey whose
footprint is much larger than that of typical microlensing searches, but with
far-from-optimal time sampling. To examine the probability that microlensing
events can be recovered in these data, we test statistics used on uniformly
sampled data to identify variables and transients. We find that the von Neumann
ratio performs best for identifying simulated microlensing events in our data.
We develop a selection method using this statistic and apply it to data from
fields with 10 -band observations, light curves,
uncovering three candidate microlensing events. We lack simultaneous,
multi-color photometry to confirm these as microlensing events. However, their
number is consistent with predictions for the event rate in the PTF footprint
over the survey's three years of operations, as estimated from near-field
microlensing models. This work can help constrain all-sky event rate
predictions and tests microlensing signal recovery in large data sets, which
will be useful to future time-domain surveys, such as that planned with the
Large Synoptic Survey Telescope.Comment: 13 pages, 14 figures; accepted for publication in ApJ. fixed author
lis
Magnetic Susceptibility of Multiorbital Systems
Effects of orbital degeneracy on magnetic susceptibility in paramagnetic
phases are investigated within a mean-field theory. Under certain crystalline
electric fields, the magnetic moment consists of two independent moments, e.g.,
spin and orbital moments. In such a case, the magnetic susceptibility is given
by the sum of two different Curie-Weiss relations, leading to deviation from
the Curie-Weiss law. Such behavior may be observed in d- and f-electron systems
with t_{2g} and Gamma_8 ground states, respectively. As a potential application
of our theory, we attempt to explain the difference in the temperature
dependence of magnetic susceptibilities of UO_2 and NpO_2.Comment: 4 pages, 3 figure
Coupling between Smectic and Twist Modes in Polymer Intercalated Smectics
We analyse the elastic energy of an intercalated smectic where
orientationally ordered polymers with an average orientation varying from layer
to layer are intercalated between smectic planes. The lowest order terms in the
coupling between polymer director and smectic layer curvature are added to the
smectic elastic energy. Integration over the smectic degrees of freedom leaves
an effective polymer twist energy that has to be included into the total
polymer elastic energy leading to a fluctuational renormalization of the
intercalated polymer twist modulus. If the polymers are chiral this in its turn
leads to a renormalization of the cholesteric pitch.Comment: 8 pages, 1 fig in ps available from [email protected] Replaced
version also contains title and abstract in the main tex
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Chemical analyses and preliminary interpretation of waters collected from the CGEH No. 1 geothermal well at Coso, California
The chloride-rich water obtained in 1967 from the shallow (114.3 m) Coso Hot Springs well No. 1 comes from a deep aquifer with a temperature at least as high as about 240/sup 0/ and possibly higher than 275/sup 0/C. Similar, but slightly diluted and cooled chloride-rich water enters the 1477-meter deep CGEH No. 1 well drilled in 1977 about 3.2 km to the west of the 1967 well. From the data in hand the Coso geothermal system appears to be a hot water type. The surface expression of fumarole and acid sulfate pools and shallow steam wells gives a false indication of an extensive vapor dominated system because upward convecting, boiling alkaline-chloride waters do not reach the surface
Photonic Clusters
We show through rigorous calculations that dielectric microspheres can be
organized by an incident electromagnetic plane wave into stable cluster
configurations, which we call photonic molecules. The long-range optical
binding force arises from multiple scattering between the spheres. A photonic
molecule can exhibit a multiplicity of distinct geometries, including
quasicrystal-like configurations, with exotic dynamics. Linear stability
analysis and dynamical simulations show that the equilibrium configurations can
correspond with either stable or a type of quasi-stable states exhibiting
periodic particle motion in the presence of frictional dissipation.Comment: 4 pages, 3 figure
Structural Controls on Crustal Fluid Circulation and Hot Spring Geochemistry Above a Flat‐Slab Subduction Zone, Peru
Hot spring geochemistry from the Cordillera Blanca and Cordillera Huayhuash, Peru, reveal the influence of crustal‐scale structures on geothermal fluid circulation in an amagmatic region located above a flat‐slab subduction zone. To test the influence of contrasting modes of faulting in these regions, springs were targeted along the Cordillera Blanca detachment fault, within its hanging wall, in the footwall of the detachment, and in the Cordillera Huayhuash. Hot springs along the Cordillera Blanca detachment fault zone are associated with recent extension and normal faulting, and those in its footwall and the Cordillera Huayhuash are located in the Marañon fold and thrust belt where compressional structures dominate. Springs along and in the hanging wall of the Cordillera Blanca detachment fault yield brackish‐saline, alkaline‐chloride waters, with oxygen, hydrogen, carbon, and chlorine stable isotope values that suggest mixing between meteoric groundwater and saline brine affected by high water‐rock interaction. Geothermometry reservoir temperature estimates (RTEs) of 91–226°C indicate maximum flow path depths of 8.7 or 11 km, depending on geothermal gradient, associated with the Cordillera Blanca detachment fault. In contrast, springs in the footwall and in the Cordillera Huayhuash exhibit a wide range of water types with an isotopic affinity to meteoric water, suggesting a greater influence from shallow groundwater and less water‐rock interaction. For these springs, RTEs of 40–98°C correspond to much shallower circulation (1.6–4 km). Results indicate that the Cordillera Blanca detachment system accommodates significantly deeper circulation of crustal fluids compared to other regional compressional structures
Density-functional-based predictions of Raman and IR spectra for small Si clusters
We have used a density-functional-based approach to study the response of silicon clusters to applied electric fields. For the dynamical response, we have calculated the Raman activities and infrared (IR) intensities for all of the vibrational modes of several clusters (SiN with N=3-8, 10, 13, 20, and 21) using the local density approximation (LDA). For the smaller clusters (N=3-8) our results are in good agreement with previous quantum-chemical calculations and experimental measurements, establishing that LDA-based IR and Raman data can be used in conjunction with measured spectra to determine the structure of clusters observed in experiment. To illustrate the potential of the method for larger clusters, we present calculated IR and Raman data for two low-energy isomers of Si10 and for the lowest-energy structure of Si13 found to date. For the static response, we compare our calculated polarizabilities for N=10, 13, 20, and 21 to recent experimental measurements. The calculated results are in rough agreement with experiment, but show less variation with cluster size than the measurements. Taken together, our results show that LDA calculations can offer a powerful means for establishing the structures of experimentally fabricated clusters and nanoscale systems
Minimising pain in farm animals: the 3S approach - ‘Suppress, Substitute, Soothe'
Recently, the French National Institute for Agricultural Research appointed an expert committee to review the issue of pain in food-producing farm animals. To minimise pain, the authors developed a ‘3S' approach accounting for ‘Suppress, Substitute and Soothe' by analogy with the ‘3Rs' approach of ‘Reduction, Refinement and Replacement' applied in the context of animal experimentation. Thus, when addressing the matter of pain, the following steps and solutions could be assessed, in the light of their feasibility (technical constraints, logistics and regulations), acceptability (societal and financial aspects) and availability. The first solution is to suppress any source of pain that brings no obvious advantage to the animals or the producers, as well as sources of pain for which potential benefits are largely exceeded by the negative effects. For instance, tail docking of cattle has recently been eliminated. Genetic selection on the basis of resistance criteria (as e.g. for lameness in cattle and poultry) or reduction of undesirable traits (e.g. boar taint in pigs) may also reduce painful conditions or procedures. The second solution is to substitute a technique causing pain by another less-painful method. For example, if dehorning cattle is unavoidable, it is preferable to perform it at a very young age, cauterising the horn bud. Animal management and constraint systems should be designed to reduce the risk for injury and bruising. Lastly, in situations where pain is known to be present, because of animal management procedures such as dehorning or castration, or because of pathology, for example lameness, systemic or local pharmacological treatments should be used to soothe pain. These treatments should take into account the duration of pain, which, in the case of some management procedures or diseases, may persist for longer periods. The administration of pain medication may require the intervention of veterinarians, but exemptions exist where breeders are allowed to use local anaesthesia (e.g. castration and dehorning in Switzerland). Extension of such exemptions, national or European legislation on pain management, or the introduction of animal welfare codes by retailers into their meat products may help further developments. In addition, veterinarians and farmers should be given the necessary tools and information to take into account animal pain in their management decision
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