2,931 research outputs found
Analysis and use of VAS satellite data
A series of interrelated investigations has examined the analysis and use of VAS (VISSR Atmospheric Sounder) satellite data. A case study of VAS-derived mesoscale stability parameters suggested that they would have been a useful supplement to conventional data in the forecasting of thunderstorms on the day of interest. However, the meteorological significance of small or short lived stability features was uncertain. A second investigation examined the roles of first guess and VAS radiometric data in producing sounding retrievals. The radiance data often did not have a decisive influence on the final satellite soundings. Broad-scale patterns of the first guess, radiances, and retrievals frequently were similar, whereas small scale retrieval features, especially in the dew points, were often of uncertain origin
Analysis and use of VAS satellite data
Four interrelated investigations have examined the analysis and use of VAS satellite data. A case study of VAS-derived mesoscale stability parameters suggested that they would have been a useful supplement to conventional data in the forecasting of thunderstorms on the day of interest. A second investigation examined the roles of first guess and VAS radiometric data in producing sounding retrievals. Broad-scale patterns of the first guess, radiances, and retrievals frequently were similar, whereas small-scale retrieval features, especially in the dew points, were often of uncertain origin. Two research tasks considered 6.7 micron middle tropospheric water vapor imagery. The first utilized radiosonde data to examine causes for two areas of warm brightness temperature. Subsidence associated with a translating jet streak was important. The second task involving water vapor imagery investigated simulated imagery created from LAMPS output and a radiative transfer algorithm. Simulated image patterns were found to compare favorably with those actually observed by VAS. Furthermore, the mass/momentum fields from LAMPS were powerful tools for understanding causes for the image configurations
Scaling Functions for Baby Universes in Two-Dimensional Quantum Gravity
We apply the recently proposed transfer matrix formalism to 2-dimensional
quantum gravity coupled to minimal models. We find that the
propagation of a parent universe in geodesic (Euclidean) time is accompanied by
continual emission of baby universes and derive a distribution function
describing their sizes. The limit is generally
thought to correspond to classical geometry, and we indeed find a classical
peak in the universe distribution function. However, we also observe dramatic
quantum effects associated with baby universes at finite length scales.Comment: 20 pages, 6 figures (not included, available upon request), PUPT-142
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Self-potential observations during hydraulic fracturing
The self-potential (SP) response during hydraulic fracturing of intact Sierra granite was investigated in the laboratory. Excellent correlation of pressure drop and SP suggests that the SP response is created primarily by electrokinetic coupling. For low pressures, the variation of SP with pressure drop is linear, indicating a constant coupling coefficient (Cc) of -200 mV/MPa. However for pressure drops >2 MPa, the magnitude of the Cc increases by 80% in an exponential trend. This increasing Cc is related to increasing permeability at high pore pressures caused by dilatancy of micro-cracks, and is explained by a decrease in the hydraulic tortuosity. Resistivity measurements reveal a decrease of 2% prior to hydraulic fracturing and a decrease of {approx}35% after fracturing. An asymmetric spatial SP response created by injectate diffusion into dilatant zones is observed prior to hydraulic fracturing, and in most cases this SP variation revealed the impending crack geometry seconds before failure. At rupture, injectate rushes into the new fracture area where the zeta potential is different than in the rock porosity, and an anomalous SP spike is observed. After fracturing, the spatial SP distribution reveals the direction of fracture propagation. Finally, during tensile cracking in a point load device with no water flow, a SP spike is observed that is caused by contact electrification. However, the time constant of this event is much less than that for transients observed during hydraulic fracturing, suggesting that SP created solely from material fracture does not contribute to the SP response during hydraulic fracturing
The extent of violence inflicted on adolescent Aboriginal girls in the Northern Territory
Background:
Australian Aboriginal and Torres Strait Islander women are at very high risk of violence but there is little evidence about the age at which their higher exposure to violence commences. The aim of this study was to investigate violence inflicted on Aboriginal girls during childhood and adolescence, relative to Aboriginal boys and non-Aboriginal girls.
Methods:
This was a retrospective cohort study using de-identified administrative data for NT residents aged 0-17âyears. This study used linked hospital and child protection data to investigate hospitalization for injury caused by assault and substantiated child maltreatment involving violence (physical and sexual abuse).
Results:
The incidence of assault hospitalization and substantiated physical/sexual abuse was much higher for Aboriginal than non-Aboriginal adolescents but similar for girls and boys to about age ten, then increased much more for Aboriginal girls than boys. In the 14-17 age-group, assault hospitalization incidence was 125% higher for Aboriginal girls than boys but 56% lower for non-Aboriginal girls than boys. 4.6% of Aboriginal girls were hospitalized (30.9% more than once) for assault between twelfth and eighteenth birthdays, compared to 3.4% of Aboriginal boys and 0.3% of non-Aboriginal girls. The incidence of assault hospitalization during adolescence was over three times higher for Aboriginal children who had substantiated child maltreatment during childhood.
Conclusion:
The very high levels of violence suffered by Aboriginal women commence in the pre-teen years. Non-Aboriginal girls are âprotectedâ from the rising levels of violence that boys experience as they progress through adolescence, but Aboriginal girls are not afforded such protection
New renewably-sourced polyesters from limonene-derived monomers
The functionalisation of limonene has enabled the synthesis of two renewably-sourced monomers for the formation of terpene-derived polyesters. Three methods for the synthesis of the novel hydroxy-acid 6 are reported and their green-credentials scrutinised through comparison of their sustainability-metrics. Step-growth homo-polymerisation of 6 is demonstrated to yield a low molecular weight (2.6 kDa) novel polyester with 100% of its carbon content originating from the terpene starting material. The corresponding diol 2 is shown to act as a co-monomer with a renewable diacid. The resultant polyesters display impressive Mns of up to 30 kDa with Tgs between â6 and 24 °C. These materials have been shown to depolymerise under basic conditions for reclamation of the diol monomer 2
Targeted muscle reinnervation for the management of pain in the setting of major limb amputation
The life altering nature of major limb amputations may be further complicated by neuroma formation in up to 60% of the estimated 2 million major limb amputees in the United States. This can be a source of pain and functional limitation of the residual limb. Pain associated with neuromas may limit prosthetic limb use, require reoperation, lead to opioid dependence, and dramatically reduce quality of life. A number of management options have been described including excision alone, excision with repair, excision with transposition, and targeted muscle reinnervation. Targeted muscle reinnervation has been shown to reduce phantom limb and neuroma pain for patients with upper and lower extremity amputations. It may be performed at the time of initial amputation to prevent pain development or secondarily for the treatment of established pain. Encouraging outcomes have been reported, and targeted muscle reinnervation is emerging as a leading surgical technique for pain prevention in patients undergoing major limb amputations and pain management in patients with pre-existing amputations
Towards a nonsupersymmetric string phenomenology
Over the past three decades, considerable effort has been devoted to studying the rich and diverse phenomenologies of heterotic strings exhibiting spacetime supersymmetry. Unfortunately, during this same period, there has been relatively little work studying the phenomenologies associated with their nonsupersymmetric counterparts. The primary reason for this relative lack of attention is the fact that strings without spacetime supersymmetry are generally unstable, exhibiting large one-loop dilaton tadpoles. In this paper, we demonstrate that this hurdle can be overcome in a class of tachyon-free four-dimensional string models realized through coordinate-dependent compactifications. Moreover, as we shall see, it is possible to construct models in this class whose low-lying states resemble the Standard Model (or even potential unified extensions thereof)âall without any light superpartners, and indeed without supersymmetry at any energy scale. The existence of such models thus opens the door to general studies of nonsupersymmetric string phenomenology, and in this paper we proceed to discuss a variety of theoretical and phenomenological issues associated with such nonsupersymmetric strings. On the theoretical side, we discuss the finiteness properties of such strings, the general characteristics of their mass spectra, the magnitude and behavior of their one-loop cosmological constants, and their interpolation properties. By contrast, on the phenomenological side, the properties we discuss are more model-specific and include their construction techniques, their natural energy scales, their particle and charge assignments, and the magnitudes of their associated Yukawa couplings and scalar masses
Deriving snow water equivalent using cosmic-ray neutron sensors from the COSMOS-UK network for modelling snowmelt floods
The COSMOS-UK sensor network has the potential to provide new insights into extreme snowfall and snowmelt
events in the UK and to improve the modelling of snowmelt floods. The network consist of approximately 50
measurement sites, each equipped with a Cosmic-Ray Neutron Sensor (CRNS). A number of these sites additionally
include a âSnowFoxâ sensor for measuring snow water equivalent (SWE) and an ultrasonic snow depth sensor.
Although the CRNS is currently used to produce estimates of soil moisture, it is also sensitive to water
held as a snowpack. Moreover, the large (hundreds of metres) footprint of the CRNS potentially allows representative
measurements of SWE even for inhomogeneous snowpacks. However, to date, there has been little attempt
to produce snow products using the COSMOS-UK network, and soil moisture estimates during snowfall events
are simply removed from the record.
Here, a method is developed for using the COSMOS-UK network to derive snow products for the UK,
where shallow, ephemeral snowpacks are the norm. The challenges posed by noise from the random nature of
cosmic ray events, and the problem of separating the snow signal from moisture within the soil, are discussed. A
comparison is made of SWE derived from the COSMOS-UK network and modelled using the snow hydrology
component of the Grid-to-Grid (G2G) distributed hydrological model, and the effect on simulated river flows
discussed
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