3,673 research outputs found
Comparison of Periglacial Block Fields and Talus Slopes in South-Central Pennsylvania and Northern Maryland
Relict periglacial boulder fields, or block fields, are scattered across south-central Pennsylvania and northern Maryland (e.g. Potter and Moss, 1968; Denn et al 2018). This pilot study uses a combination of digital analyses using Google Earth Pro and fieldwork to investigate block fields at different scales. Fieldwork focused on two block fields, which were compared with fieldwork conducted on two talus slopes. The block fields studied were Raven Rock Hollow in Maryland and River of Rocks at Hawk Mountain in Pennsylvania, and the talus slopes were located at Catoctin Mountain, Maryland and Waggoner’s Gap, Pennsylvania. The importance of geomorphic processes on formation of block fields compared to talus slopes was examined as part of this pilot study
Cal Poly Nano Hydro
This projects goal was to design, construct, and test a machine capable of generating a usable amount of energy from naturally flowing water. The device conceived for this purpose is a portable raft with a turbine mounted to the underside. The turbine is mated directly to a low angular velocity generator which outputs to a power electronics system on shore. Using a Gorlov Helical turbine, this proof-of-concept is designed to output ~50 Watts of electricity to charge a battery for later use. Possible applications for this device include camping in remote locations, supplemental power generation for a home, or for powering off-the-grid locations in developing countries
Neutrino-induced deuteron disintegration experiment
Cross sections for the disintegration of the deuteron via neutral-current
(NCD) and charged-current (CCD) interactions with reactor antineutrinos are
measured to be 6.08 +/- 0.77 x 10^(-45) cm-sq and 9.83 +/- 2.04 x 10^(-45)
cm-sq per neutrino, respectively, in excellent agreement with current
calculations. Since the experimental NCD value depends upon the CCD value, if
we use the theoretical value for the CCD reaction, we obtain the improved value
of 5.98 +/- 0.54 x 10^(-45) for the NCD cross section. The neutral-current
reaction allows a unique measurement of the isovector-axial vector coupling
constant in the hadronic weak interaction (beta). In the standard model, this
constant is predicted to be exactly 1, independent of the Weinberg angle. We
measure a value of beta^2 = 1.01 +/- 0.16. Using the above improved value for
the NCD cross section, beta^2 becomes 0.99 +/- 0.10.Comment: 22pages, 9 figure
Understanding Hadley Cell Expansion versus Contraction: Insights from Simplified Models and Implications for Recent Observations
This study seeks a deeper understanding of the causes of Hadley Cell (HC) expansion, as projected under global warming, and HC contraction, as observed under El Niño. Using an idealized general circulation model, the authors show that a thermal forcing applied to a narrow region around the equator produces “El Niño–like” HC contraction, while a forcing with wider meridional extent produces “global warming–like” HC expansion. These circulation responses are sensitive primarily to the thermal forcing’s meridional structure and are less sensitive to its vertical structure. If the thermal forcing is confined to the midlatitudes, the amount of HC expansion is more than three times that of a forcing of comparable amplitude that is spread over the tropics. This finding may be relevant to recently observed trends of rapid tropical widening.
The shift of the HC edge is explained using a very simple model in which the transformed Eulerian mean (TEM) circulation acts to diffuse heat meridionally. In this context, the HC edge is defined as the downward maximum of residual vertical velocity in the upper troposphere Ď–max *; this corresponds well with the conventional Eulerian definition of the HC edge. In response to a positive thermal forcing, there is anomalous diabatic cooling, and hence anomalous TEM descent, on the poleward flank of the thermal forcing. This causes the HC edge (Ď–max *) to shift toward the descending anomaly, so that a narrow forcing causes HC contraction and a wide forcing causes HC expansion
Some Ranking and Selection Criteria for Determining Sample Sizes in Two Different Models for a Drug Combination Problem
1 online resource (PDF, 26 pages
Candida Urinary Tract Infection: Pathogenesis
Candida species are unusual causes of urinary tract infection (UTI) in healthy individuals, but common in the
hospital setting or among patients with predisposing diseases and structural abnormalities of the kidney and
collecting system. The urinary tract may be invaded in either an antegrade fashion from the bloodstream or
retrograde via the urethra and bladder. Candida species employ a repertoire of virulence factors, including
phenotypic switching, dimorphism, galvano - and thigmotropism, and hydrolytic enzymes, to colonize and then
invade the urinary tract. Antegrade infection occurs primarily among patients predisposed to candidemia. The
process of adherence to and invasion of the glomerulus, renal blood vessels, and renal tubules by Candida
species was elegantly described in early histopathologic studies. Armed with modern molecular biologic
techniques, the various virulence factors involved in bloodborne infection of the kidney are gradually being
elucidated. Disturbances of urine flow, whether congenital or acquired, instrumentation of the urinary tract,
diabetes mellitus, antimicrobial therapy, and immunosuppression underlie most instances of retrograde
Candida UTI. In addition, bacterial UTIs caused by Enterobacteriaceae may facilitate the initial step in the
process. Ascending infections generally do not result in candidemia in the absence of obstruction
Candida Urinary Tract Infection: Pathogenesis
Candida species are unusual causes of urinary tract infection (UTI) in healthy individuals, but common in the
hospital setting or among patients with predisposing diseases and structural abnormalities of the kidney and
collecting system. The urinary tract may be invaded in either an antegrade fashion from the bloodstream or
retrograde via the urethra and bladder. Candida species employ a repertoire of virulence factors, including
phenotypic switching, dimorphism, galvano - and thigmotropism, and hydrolytic enzymes, to colonize and then
invade the urinary tract. Antegrade infection occurs primarily among patients predisposed to candidemia. The
process of adherence to and invasion of the glomerulus, renal blood vessels, and renal tubules by Candida
species was elegantly described in early histopathologic studies. Armed with modern molecular biologic
techniques, the various virulence factors involved in bloodborne infection of the kidney are gradually being
elucidated. Disturbances of urine flow, whether congenital or acquired, instrumentation of the urinary tract,
diabetes mellitus, antimicrobial therapy, and immunosuppression underlie most instances of retrograde
Candida UTI. In addition, bacterial UTIs caused by Enterobacteriaceae may facilitate the initial step in the
process. Ascending infections generally do not result in candidemia in the absence of obstruction
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Western North Pacific tropical cyclone model tracks in present and future climates
Western North Pacific tropical cyclone (TC) model tracks are analyzed in two large multimodel ensembles, spanning a large variety of models and multiple future climate scenarios. Two methodologies are used to synthesize the properties of TC tracks in this large data set: cluster analysis and mass moment ellipses. First, the models' TC tracks are compared to observed TC tracks' characteristics, and a subset of the models is chosen for analysis, based on the tracks' similarity to observations and sample size. Potential changes in track types in a warming climate are identified by comparing the kernel smoothed probability distributions of various track variables in historical and future scenarios using a Kolmogorov-Smirnov significance test. Two track changes are identified. The first is a statistically significant increase in the north-south expansion, which can also be viewed as a poleward shift, as TC tracks are prevented from expanding equatorward due to the weak Coriolis force near the equator. The second change is an eastward shift in the storm tracks that occur near the central Pacific in one of the multimodel ensembles, indicating a possible increase in the occurrence of storms near Hawaii in a warming climate. The dependence of the results on which model and future scenario are considered emphasizes the necessity of including multiple models and scenarios when considering future changes in TC characteristics
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