4,908 research outputs found
QCD sum rule analysis of excited mass parameter
The mass parameter of orbitally excited baryons is calculated by
using QCD sum rule in the framework of heavy quark effective theory. Two kinds
of interpolating current for the excited heavy baryons are introduced. It is
obtained that GeV for the non-derivative
current and GeV for the current with
derivative. These results are consistent with experimental data.Comment: 12 pages, 3 figures, to appear in PL
Wandering globular clusters: the first dwarf galaxies in the universe?
In the last decade we witness an advent of new types of dwarf stellar systems
in cluding ultra-compact dwarfs, ultra-faint dwarf spheroidals, and exotic
globular clusters, breaking the old simple paradigm for dwarf galaxies and
globular clusters. These objects become more intriguing, and understanding of
these new findings be comes more challenging. Recently we discovered a new type
of large scale structure in the Virgo cluster of galaxies: it is composed of
globular clusters. Globular clusters in Virgo are found wandering between
galaxies (intracluster globular clusters) as well as in galaxies. These
intracluster globular clusters fill a significant fraction in the area of the
Virgo cluster and they are dominated by blue globular clusters. These
intracluster globular clusters may be closely related with the first dwarf
galaxies in the universe.Comment: 6 pages, 3 figures, Conference Proceedings: "A Universe of Dwarf
Galaxies", 14-18 June 2010, Lyon, Franc
An immunohistochemical study of the pancreatic endocrine cells of the Korean golden frog, Rana plancyi chosenica
The regional distribution and quantitative frequency of pancreatic endocrine cells were demonstrated in the Korean golden frog (Rana plancyi chosenica Okada), which is known as a Korean endemic species, for the first time by immunohistochemical methods using specific mammalian antisera to insulin, glucagon, somatostatin and human pancreatic polypeptide (PP). In the pancreas of the Korean golden frog, all four endocrine cell types were demonstrated. Insulin- and glucagon-positive cells were located in the pancreas as single cells or islet-like clusters, respectively. Somatostatin-containing cells were also dispersed in the pancreas as single cells or clusters but in the case of clusters, they are exclusively situated in the marginal regions of insulin- or glucagon-positive cell clusters. PP-containing cells were also distributed as single cells or clusters. Clusters consisted of PP-positive cells are distributed as a core type and a marginally distributed type. Overall, there were 40.84±3.81% insulin-, 26.02±1.71% glucagon-, 7.63±2.09% somatostatin- and 25.51±3.26% PP-IR cells
Storm surge, wave, and inundation simulation in the bay of Bengal
Bangladesh's geographical and land characteristics along the coastal area has created the most disastrous country by tropical cyclones originating in the Bay of Bengal and associated with the storm surges. During the past 61 years (1950-2011), India Meteorology Department (IMD) was observed 902 events from deep depression (tropical\ud
storm) up to super cyclonic storm (tropical cyclone category 5) with average 5 storms per year. This condition is strengthening storm surge and increasing sea level to the sudden inundation and flooding along the Bangladesh coast. Consequently, the storm surge and sea level rise are the key factor of coastal damage. Therefore, it is critical to estimate the future storm surges in a changing climate for vulnerability study and adaptation strategy. In this study, numerical simulations are performed to validate the storm surge induced by the 1991 Bangladesh cyclone, one of the deadliest cyclone in the Bay of Bengal using an atmosphere-waves-ocean integrated modelling system. Then, further numerical experiments are performed to estimate the future storm surges in 2050 and 2080 and inundation map for Bangladesh's disaster management strategy
Wintertime extreme storm waves in the East sea (Japan sea): Numerical experiments of storm wave overtopping in the Fushiki port, the Toyama bay
In the winter East Sea (ES), storm waves due to winter storms (e.g. extratropical cyclones) under the context of the cold and dry East Asian winter monsoon are frequently reported causing extensive coastal damages along the coasts of Korea and Japan. In February 2008, abnormal storm waves due to a moving low propagating from the west off Hokkaido, Japan, to the south and southwest caused severe coastal damages along the Toyama Bay coast. In this study, we perform numerical experiments on wave overtopping and run-up in the Fushiki Port, Toyama Bay, where the long North-Breakwater was heavily damaged by the storm waves in February 2008. The experiments are conducted using an open-source Gerris flow solver (Gfs) based on modified non-linear shallow-water equation with adaptive mesh refinement (AMR) method and wet-dry scheme for the potential extreme storm waves of 6.78 m and 18.28 sec obtained from statistical analysis and wind wave modeling. The refined mesh efficiently resolves the complicated coastline and coastal structures in the Fushiki Port. The results show that the Fushiki Port would be overtopped and flooded by extreme storm waves if the North-Breakwater does not function properly after being damaged. Also the storm waves would overtop seawalls and sidewalls of the Manyou Pier behind the North-Breakwater. The results also depict that AMR method and wet-dry scheme capture the coastline and coastal structure very well while keeping the computational load efficiently
Wintertime extreme storm waves in the East sea (Japan sea): Estimation of extreme storm waves in the Toyama bay, Japan
In the winter East Sea (ES), abnormal high waves due to the cold and dry East Asian winter monsoon and winter storms (extratropical cyclones) are often reported causing large coastal damages along the coasts of ES. In February 2008, abnormal storm waves due to a developed atmospheric low pressure system propagating from the west off Hokkaido, Japan, to the south and southwest throughout the ES caused extensive damages along the central coast of Japan and along the east coast of Korea. In this study, we investigate a potential extreme storm wave, Yorimawari Waves in Japanese, in the Toyama Bay where the coastal structures were heavily damaged by the storm waves in February 2008. Three factors for wind wave growing, such as wind intensity, duration and fetch, are investigated for their extreme conditions based on historical data and empirical formula. Then, numerical experiments are conducted to estimate extreme wave characteristics in the Toyoma Bay using a meso-scale non-hydrostatic meteorological model, WRF, and a spectral wave model, WAVEWATCH III. The results from numerical experiments depict the potential significant wave height of 6.78 m and corresponding wave period of 18.28 sec at the Fushiki-Toyama Port in the Toyama Bay
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Visualization Tools for Design Support in SFF 437
When considering the use of SFF, there are many questions a designer might ask. What model orientation should be used, will the model have adequate aesthetic and functional properties, is the STL file suitable for transfer to the SFF machine? These questions could be answered by a comprehensive design support system for SFF. This paper addresses a number of components for such a system that can be met through the use of visualization tools. These include: 1. Visualization of surface roughness 2. Visualization of characteristic features (e.g. surface macro-texture) 3. Visual simulation of fabrication Example applications of these tools are presented together with a status review of their implementation to date. It is envisaged that these tools will be incorporated into an already existing network-based preprocessor used for visualization, repair and slicing of STL files. The direction of future work is also discussed which will include the visual representation of functionally graded materials (connected with FEM results).Mechanical Engineerin
Some Parameter Boundaries Governing Microgravity Pool Boiling Modes
Pool boiling experiments were conducted in microgravity on five space shuttle flights, using a flat plate heater consisting of a semitransparent thin gold film deposited on a quartz substrate that also acted as a resistance thermometer. The test fluid was R-113, and the vapor bubble behavior at the heater surface was photographed from beneath as well as from the side. Each flight consisted of a matrix of three levels of imposed heat flux and three levels of initial bulk liquid subcooling. In many of the total of 45 experiments, steady nucleate boiling was observed from 16-mm movie films, where a large vapor bubble formed and remained slightly removed from the heater surface, with small vapor bubbles growing on the heater surface, and on contact coalescing with the large bubble. Computations of the forces associated with the momentum transfer in this process, which counters the Marangoni convection effects tending to impel the large bubble toward the heater surface, have been completed for all cases where applicable. The modes of pool boiling observed with successive increases in levels of heat flux in microgravity are categorized as: (i) minimum or incipient nucleate boiling; (ii) nucleate boiling with vigorous motion of the bubbles adjacent and parallel to the heater surface, impelled by Marangoni convection effects; (iii) nucleate boiling followed by coalescence with a neighboring large vapor bubble; (iv) partial dryout of the heater surface, in parallel with nucleate boiling; (v) complete dryout. The boundaries between these modes are delineated graphically as a function of the imposed heat flux and initial bulk liquid subcooling, together with the levels of the forces holding the large bubbles, acting as vapor reservoirs, away from the heater surface for the steady nucleate boiling mode.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72880/1/annals.1362.017.pd
The Beta Generalized Exponential Distribution
We introduce the beta generalized exponential distribution that includes the
beta exponential and generalized exponential distributions as special cases. We
provide a comprehensive mathematical treatment of this distribution. We derive
the moment generating function and the th moment thus generalizing some
results in the literature. Expressions for the density, moment generating
function and th moment of the order statistics also are obtained. We discuss
estimation of the parameters by maximum likelihood and provide the information
matrix. We observe in one application to real data set that this model is quite
flexible and can be used quite effectively in analyzing positive data in place
of the beta exponential and generalized exponential distributions
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