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Bose-Einstein Condensation: Building the Testbeds to Study SuperfluidityNaik, Devang S. 11 September 2006 (has links)
Since Feynman's realization of using quantum systems to investigate quantum dynamics, interest in creating controllable quantum systems to simulate condensed matter phenomenon has been high. With the realization of BECs in 1995, the realization of a relatively clean testbed for simulating some of these phenomenon became a reality.
My PhD research has been an exploration of the production and use of Bose-Einstein Condensates for the study of superfluidity. The first 3 years have been spent in the actual building of a Na BEC apparatus. During this time, we’ve implemented a distinct technique to trap ultra cold Na atoms, i.e. the Optically Plugged Trap. In the process, we have shown how atoms in a linear trap can show spin metastability and thus maintain a nonequilibrium state for long periods of time.
In studying the interaction of ultra-cold atoms with light, we have developed a technique to measure the velocity distribution of atoms using a standing optical wave (Bragg Spectroscopy). Alongside this, we have also created optical traps for atoms in which we can change to shape of the trap itself to probe different condensed matter systems. The eventual goal being the investigation of condensed matter physics, specifically superfluidity, using ultra-cold atoms.
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IDENTIFICATION OF DROUGHT-RELATED QUANTITATIVE TRAIT LOCI (QTLs) IN SUGARCANE (Saccharum spp.) USING GENIC MARKERSSharma, Vivek 2009 May 1900 (has links)
Population based association studies in crops that were established by domestication and
early breeding can be a valuable basis for the identification of QTLs. A case control
design in a population is an ideal way to identify maximum candidate sites contributing
to a complex polygenic trait such as drought. In the current study, marker loci associated
with drought related QTLs were identified in sugarcane (Saccharum spp), one of the
most complex crop genomes, with its polyploid nature (>8), chromosome number
(>100) and interspecific origin. The objectives of this investigation were: 1)
development of genic markers, which can be used for marker-assisted selection of
drought tolerant genotypes of sugarcane. 2) genotypic characterization of sugarcane
population at drought related loci using EST-SSR markers. Using 55 microsatellite
markers, 56 polymorphisms were scored among 80 modern sugarcane genotypes.
Homogeneity of the population was confirmed by determining the distribution of allele
frequencies obtained by random genomic microsatellite markers. This analysis was
conducted in the STRUCTURE program and the population was divided in 3 subgroups
based on the allelic distribution. Phenotypic data to evaluate drought tolerance among
the genotypes was collected by measuring chlorophyll content, chlorophyll fluorescence,
leaf temperature and leaf relative water content. A generalized linear model in SPSS was
used to find association between marker loci and phenotypic data. Markers with
significant association (P 0.001 level) with the trait were subjected to linear regression
to screen the spurious associations. Based on the results, 21 EST-SSR markers and 11 TRAP markers related to drought-defining physiological parameters were considered as
genuine associations in this study. Fifty-six polymorphisms produced by 13 EST-SSR
primers were used to produce genetic similarity matrix for 80 genotypes. Dendrogram
prepared from this genetic similarity matrix will be useful in selecting parents carrying
diversity at drought specific loci.
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Ion Crystals Produced by Laser and Sympathetic Cooling in a Linear RF Ion TrapZhu, Feng 2010 December 1900 (has links)
A detailed investigation of ion crystals produced by laser and sympathetic cooling in a linear RF trap has been conducted.
The laser cooling methods were examined and applied to the trapped ^24Mg^(positive) ions. The crystals produced by the laser cooling were studied, including the dependence on RF voltage, end cap DC voltage, laser power and laser frequency. By manipulating the different RF voltages and endcap DC voltages, the structure phase transition of the ion crystals was observed.
In addition, the sympathetic cooling of different ion species with the laser cooled 24Mg^(positive) was carried out. In this process, the mixed Mg^(positive) and He^(positive) crystals were created andidentified, and mixed Mg^(positive) and H2^(positive) crystals were produced. The effect of an unwanted chemical reaction of Mg^(positive) and H2 was observed and minimized. After sympathetic cooling of light ion species, the sympathetic cooling of heavy molecular ions such as fullerene ions was also carried out. The efficiencies and final temperature in both cases are very different. Theoretically to interpret the results, molecular dynamics simulations of the laser cooling and sympathetic cooling were implemented. And the simulations were compared with the experimental results.
In the process of carrying out this research, the optics were rebuilt to provide reliable UV sources for the photoionization and laser cooling of Mg ions. The imaging
system was reconfigured to take the images of ion crystals. New elements were added tin the ion trap to improve the ability to manipulate ions.
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Abatement Strategies and Disease Assessment for Feral Hogs in East TexasSumrall, Samuel Aaron 2011 May 1900 (has links)
Feral hogs (Sus scrofa) are considered an exotic, free-ranging ungulate distributed within numerous countries and continents to include the United States. The reproductive efficiency, lack of predators, land use practices for domestic livestock (e.g., feeding stations, introduced water sources, intense cropping practices, etc.), and diet are leading factors in the expansion of feral hogs throughout their range. Feral hogs negatively impact floral and faunal communities, agricultural lands, and residential and recreational areas to include concerns with public safety and disease transmission. My study objectives were to (1) assess feral hog abatement strategies by (A) evaluating trap designs with the inclusion of electrical fencing, and (B) evaluating candidate baits for feral hog-specificity, and (2) assess prevalence levels for feral hog diseases. I evaluated 3 corral trap designs differing in the addition of electric fence configurations. Feral hog capture success data were collected and used to determine trap design efficacy. Treatments evaluated included (A) control corral trap with no electrical configurations, (B) corral trap with 1 electrical leg, and (C) corral trap with 2 electrical legs. ANOVA analyses suggest no differences (df = 2, P = 0.758) between trap designs; however, length of trapping effort (i.e., the number of days that trapping occurred) was a significant (df = 6, P < 0.001) factor in determining trap success. Pre-baiting was an important factor in observed trapping success. Trapping success declined after fourth day of continuous trapping. I recommend short, intensive trapping efforts (e.g., <4 days) when using corral traps in feral hog abatement programs. I also evaluated 14 candidate baits (with and without repellant) replicated 40 times to determine feral hog specificity. Three evaluated baits (i.e., PIGOUT™ strawberry, corn, and rice) were selected (df = 2, P < 0.05) more frequently by feral hogs than other combinations. Non-target species (e.g., raccoons) visited baits with repellants less (df = 2, P < 0.05) than baits without repellants. Repellant had no direct impact on feral hog visitation at bait sites. Trapping data also suggests that grains commonly farmed in local or regional areas are more likely to be consumed by feral hogs and, therefore considered in baiting options. Finally, of 412 feral hogs captured, 86 were sampled for prevalence of pseudorabies and Brucella suis. The prevalence of pseudorabies and B. suis was 20.9% and 13.9%, respectively within the study area. Based on disease study results, I recommend that natural resource managers take necessary precautions to protect themselves by wearing protective equipment and equipment and properly cooking feral hog meat. Additionally, resource managers should properly administer vaccinations to domestic and companion animals, and restricting domestic and companion animals from areas of high risk (e.g., carcasses of dead hogs and wallows).
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Effect of Thinning on Ground-dwelling Beetle Communities in a Taiwania PlantationHung, Mei-jhu 26 July 2005 (has links)
The spatial distribution and monthly fluctuation of beetle species were studied in the experimental forests of Liu-Kuei Station, Taiwan Forestry Research Institute, Taiwan. Beetles were surveyed using pitfall traps from January to December, 2004. Our result showed that species richness, abundance and Shannon diversity of beetles were significant higher in Natural Forest than those of the others, and species richness and abundance were lowest in Taiwania Plantation. The composition and trophic structure of beetle community in the Thinning Plantation resulting from thinning were compared with that in the Taiwania Plantation and natural forest. Beetles communities of Natural Forest, Taiwania Plantation and Thinning Plantation were separated from each other by ordination (PCA), meaning three forest stands have distinct species assemblages. The three group assemblages were also revealed by cluster analysis. The ground-surface air humidity, litter litter depth and herbs cover were major environment factors influencing the beetle distribution. The relative size of trophic guilds in the Thinning Plantation has changed compared to Taiwania Plantation. Detritivores increased significantly in the Thinning Plantation, suggested an increase of nutrient-cycle in the Plantation. Eight dominant beetle families that were Carabidae, Scarabaeidae, Curculionidae, Staphylinidae, Scydmaenidae, Erotylidae, Nitidulidae and Biphyllidae showed different pattern of population fluctuation. The peak mainly from March to June, and Curculionidae, Scarabaeidae, Nitidulidae also show a moderate peak in August and September. In the two plantation areas, most dominant taxa showed a similarly fluctuation patterns, which are slightly different to those of Natural Forest.
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Temporal and Spatial Variability of Organic Carbon Isotopic Compositions of Particles Collected from Sediment Traps in the Western Okinawa TroughChuang, Tzu-Shen 14 July 2000 (has links)
Abstract
This study is to investigate the spatial and temporal variabilities of geochemical and carbon isotopic compositions of particles collected in the region off northeast Taiwan. Organic carbon isotopic compositions (d13Corg), total organic carbon content (TOC) and C/N ratio were determined in sediment particles collected at different water depths from three time-series sediment traps (at T12, T13, and T18 stations, respectively). The results showed abnormally high mass fluxes than those previously found. Generally they increase with water depths, implying both the transport from Lanyang-Hsi River and the resuspension from the seafloor. TOC contents range from 0.5 to 1.5wt% and decrease with depths. This can be attributed to changes in the surface productivity, lateral transport and organic preservation. The organic carbon isotopic compositions range between -21 and -25o/oo, which falls well within the d13Corg values of continental margin sediments. The lower d13Corg values at T12 station than those at T13 station can be attributed to the large terrestrial inputs. It is noted that d13Corg values decrease with depths, suggesting a significant contribution of the horizontal transport of particles to the settling process.
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Settling Particulates on the Continental Slope off Northeast Taiwan ¡GMass Flux ¡AGrain Size Distribution and Disequilibrium between Lead-210 and Polonium-210Hung, Gwo-Wei 01 February 2001 (has links)
Previous studies have shown that the continental shelf and slope area off
northeastern Taiwan is a region where the material exchange processes between the
East China Sea and open ocean are most rigorous under the influences of the
Kuroshio and the monsoons. In order to understand the topographic effects on the
particulate flux and the transport path of the settling particles in this region, this study
has conducted a series of field measurements using time-series sediment traps and
current meters as tools. The temporal and spatial variations on the current, the
particulate flux and the particle-size distribution as well as the activity and flux of
210 Pb and 210 Po are presented in this thesis.
The biological productivity and the runoff of main rivers from Taiwan were not
correlated with the particulate fluxes in our study area. However, the variations of
the particulate flux in the canyon and on the slope areas were clearly affected by the
tidal currents, showing good positive correlation with their amplitudes. The
particulate, 210 Pb and 210 Po fluxes all showed an increase toward the ocean bottom but
a decrease away from the shore, suggesting that the transports of particle and particle
reactive elements were strongly influenced by the lateral transport process in the study
area. Highest fluxes were observed in the Mien-Hua Canyon(MHC) and the lower
slope southwest of the canyon. Intermediate values were observed in the South
Okinawa Trough and the North Mien-Hua Canyon(NMHC). The intercanyon slope
and the shallow traps in the NMHC had lowest values. The particulates and
particle reactive elements were transported out of the shelf or upper slope area
essentially through the MHC toward the slope southwest of the canyon. The NMHC
and the intercanyon area were not major pathways for these materials. The fluxes of
particle, 210 Pb and 210 Po in the study area were generally at least an order of
magnitude greater than those observed from other continental margins in the world,
except for the lowest values at the intercanyon station and the shallow water in the
NMHC. Thus the continental margin off northeastern Taiwan is one of the most
important areas for material exchanges with open oceans in the world.
The trapped particulates were mainly silt with variable sand fractions. High
sand contents were observed in the MHC and the lower slope southwest of the canyon,
the intermediate values were in the outlet of the MHC and the NMHC, and the lowest
in the South Okinawa Trough. This shows that the sand content decreases awayfrom the shore. On the contrary, silt and clay fractions in percent increase away
from the shore. Under the influence of tidal currents, the settling sand particles in
the MHC and its adjacent lower slope were laterally transported from resuspended
sandy sediments of the continental shelf and upper slope area adjoining the head of
the MHC. The fluxes of sand, silt and clay all decreased toward the South Okinawa
Trough but increased toward the bottom. This particle-size distribution pattern also
reflected the effect of lateral transport process in the study area.
Variations of the 210 Pb activity in this study area were generally correlated
inversely with the particulate flux and the sand content, indicating the effect of
dilution of the mass flux and the sand content, but were positively correlated with the
silt and clay contents because they were major 210 Pb scavengers. No apparent
correlations of 210 Po with the mass flux and the three particle-size fractions were
observed, suggesting that the variation of 210 Po activity was not related to the mass
fluxes or the three particle-size fractions.
High 210 Pb activities were found to be associated with high contents of POC, Mn
and Fe. Correlations of 210 Pb with both Mn and Fe indicate that the oxide and
hydroxide precipitates of Mn and Fe supplied from sediments on the continental shelf,
upper slope area and submarine hydrothermal activities might serve as important
mechanisms for enhanced 210 Pb scavenging. The relationship between the 210 Pb
activity and the POC content might reflect either the settling mode of the fine particles
incorporated with fecal pellets or aggregates, or sharing the same source with fine
particles. The variatio ns of 210 Po activity were not correlated with Mn, Fe, major
components or biogenic components, implying that the association of 210 Po with
biogenic components might be masked by the enormous terrigenous materials.
Except for the upper-trap samples collected at the intercanyon slope and the
NMHC, the 210 Po activity was lower than the 210 Pb activity with 210 Po/210 Pb ratios less
than unity. Based on comparisons of 210 Pb and 210 Po with relevant parameters and
references of past studies, we can propose several possible mechanisms to explain
why the ratios were less then unity: 1. 210 Pb was preferentially scavenged by
advecting and settling particulates of terrigenous origin. 210 Po, known to be
biophilic, might remain associated with the suspended organic particulates which
could be dissolved or not settling. Moreover, the oxide and hydroxide precipitates of
Mn and Fe in the study area would further enhance the scavenging of 210 Pb. 2. The
particulates in suspension were favorable for differentiation between 210 Pb and 210 Ponuclides while those settled in sediments would allow them to grow toward the
secular equilibrium. Therefore, the trapped particulates might be in frequent
suspension and short in deposited sediments during their lateral transport. 3. The
210 Pb supplied from the East Asia aerosol in large quantity was accumulated in water
column abd carried by the Kuroshio to the study area. The intrusion and eddies of
Kuroshio off northeastern Taiwan could bring large amount of 210 Pb into the region of
continental shelf and slope, allowing particulates to scavenge 210 Pb more effectively
from the surrounding water.
The upper trap in the NMHC and that in the intercanyon site yield lowest
particulate flux but highest POC content. With less terrigenous material and more
biogenic components in these samples, 210 Po/210 Pb ratios were greater than unity and
variations of 210 Pb activity were hardly correlated with those of POC contents but
were inversely correlated with those of Mn contents. However, the 210 Po activities
of upper trap at the intercanyon site were well positively correlated with POC and PIC
contents, indicating effects of the fresh biogenic particles.
Based on the mass balance calculations of particulate and 210 Pb fluxes, current
data and other related data gathered in this study, we may infer the sedimentation
dynamics and transport path of the settling particles below 300m depth in the study
area. Under the influence of tidal oscillation, terrigenous sediments on the shelf and
the shelf break as well as the upper slope would be resuspended and carried into the
MHC and transported further away. Most of the sand particles would deposit in the
canyon while part of the silt and clay would be transported to the South Okinawa
Trough directly and the rest to the lower slope southwest of the MHC. The
particulate flux at the lower slope southwest of MHC might also have a portion of
particulates swept from the upper slope by the Kuroshio eddies. As the NMHC and
the intercanyon sites are located in the central area of the Kuroshio eddies, the
particulates from the continental shelf and upper slope area would be blocked,
resulting in very low particulate fluxes. High particulate fluxes observed in the
lower NMHC trap should largely be due to resuspension of the sediments from the
banks of the canyon.
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Pb-210 and Po-210 radioactive disequilibrium in particulates of the western South Okinawa TroughTsai, Kang-Ling 02 September 2002 (has links)
In order to understand the source, transport pathway and sink of settling particulates in the sea off northeast Taiwan, three moorings with six sediment traps (about 100 m and 300 m above bottom) were deployed on the northern slope of the Ilan ridge (T17S and T18S) and in the South Okinawa trough (T19S). The mooring deployed at T17S was lost due to a connecting ring which was rusted and broken. The duration of the mooring was 6 months (late November, 1999 to early May, 2000) with sampling intervals at 15 days each. When the moorings were recovered, seawater samples were collected for filtration near each station and a box core at T19S was also taken so that the settling particulates, suspended particulates and bottom sediments can be compared for their characteristics.
The results show that higher apparent mass fluxes were observed in January, February and early April, 2000 at T18S. The apparent mass fluxes vary between 11 and 91 g/m2/d at T18S, and between 6 and 22 g/m2/d at T19S. The time-series variations of the Pb-210 activity are between 46 and 76 dpm/g at T18S, and between 79 and 122 dpm/g at T19S, the values of which are much higher than those of T18S. The temporal Po-210 variations range between 18 and 90 dpm/g at T18S, and from 65 to 193 dpm/g at T19S. The Po-210 activity and its variation are greater at T19S than at T18S. The 210Po/210Pb activity ratios are less than unity at about 0.8 at T18S, and greater than unity at about 1.3 at T19S. The total Po-210 activity in all water columns varies between 0.2 and 16 dpm/100kg while the total Pb-210 activity varies between 28 and 43 dpm/100kg. The mean total 210Po/210Pb activity ratio is about 0.3, indicating that Po-210 was easily scavenged and removed from water columns by particulate matter. The box core taken at T19S has Po-210 activity ranging from 54 to 121 dpm/g and Pb-210 activity from 51 to 90 dpm/g. The 210Po/210Pb activity ratio is greater than unity in the upper 6 cm, indicating an excess of Po-210 activity. Below 6 cm Po-210 and Pb-210 are nearly at equilibrium.
The 210Po/210Pb activity ratios in the water columns observed after the first deployments were higher than those observed after the second deployments. However, the 210Po/210Pb activity ratios of the settling particulates collected from the first trap deployments were lower than those from the second trap deployments. These changes might be attributed to earthquakes which occurred mainly before the second mooring period. These earthquakes could have caused a large quantity of terrigenous particulates with higher 210Po/210Pb activity ratio to be transported out to the study area in addition to resuspended shelf and slope sediments. These settling particulates, being enriched in organic matter with higher activity ratio, could preferentially scavenge Po-210 from the water column, resulting in much higher 210Po/210Pb activity ratios.
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Geochemistry of Settling Materials in the Northern South China SeaTsai, Li-shan 12 September 2007 (has links)
The time-series sediment traps were deployed in the northern South China Sea (NSCS) to collect settling particles to study the spatial and temporal variations of particle fluxes, particle sources and particle compositions. Each recovered sample was analyzed to determine the particle flux, major compositions (OM, Carbonate, opal and lithogenic materials) and trace metals (Al, Fe, Mn, Cd, Zn). The data were employed to elucidate the biochemical processes in controlling particle and chemical fluxes.
The results show that the particle fluxes vary significantly in time and space, and were apparently related to terrestrial inputs and monsoon-effected processes. Episodic events such as typhoon and earthquakes also effected the fluxes considerably. Vertical fluxes generally decreased with depth for biogenic components (POC, carbonate, opal) but increased with depth for the lithogenic component. Most lithogenic fluxes below the surface were likely derived from lateral transport and decreased with distance away from Taiwan Island. Biogenic fluxes in surface layers were generally higher in winter than in otherseasons, which may be resulted from the elevated primary production in winter. Typhoons also enhanced biogenic fluxes in surface layers but biogenic fluxes were diluted in deep layers by strong lithogenic fluxes.
Carbonate dominated the biogenic fluxes in the upper layer and may play as the major ballast in the transportation of biogenic materials through the water column. The C/N ratios of organic matter increased generally with depth implying that nitrogen was preferentially decayed over carbon through the water column. Lithogenic elements such as Al, Fe, Mn were
closely correlated and increased in fluxes with depth. However, microelements associated with biogenic materials (Cd, Zn) displayed a significant decrease in content with depth, showing a rapid recycling in water columns.
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Biogenic Particle Transport in the Gaoping Submarine Canyon off Southwestern Taiwan- Comparison of T6KP and T7KP Sediment TrapsLin, Yi-Jiun 04 September 2009 (has links)
Submarine canyons are common features on continental margins worldwide. They are important natural conduits for transfer of terrigenous sediments to the deep sea, and thus, preferential pathways for shelf-slope exchange. The purpose of this study is to understand the biogenic particle transport in the seasons according two sediment trap moorings deployed in the Gaoping submarine canyon. The T6KP mooring was deployed in dry season while the T7KP mooring was deployed in wet season. Two typhoons, Kalmaegi and Fung Wong, invaded Taiwan during 16-18 and 26-29 July within the deployment of T7KP. We discussed the influence of rainfall and river discharge on biogenic particle transport based on results of the two sediment traps. The foraminiferal abundance in sediment traps in comparison with plankton tows was discussed regarding the particle transport mechanism of the water column in the Gaoping submarine canyon.
The biogenic particle transport was a tide-dominated situation and displayed a periodic variation in dry season. In wet season, fine grain fraction (less than 63 micro meter) was dominant in the particle size and sedimentary condition was flood-dominated. The sedimentary condition was back to the tide-dominated state approximately 15 days after Kalmaegi typhoon (16-18, July). The activities of 210Pb and 234Th in the lower trap of T7KP mooring were an order less than that in T6KP mooring, indicating particles scavenge nuclides of the water column less effectively in wet season than in dry season. The absolute abundances of foraminifera in the canyon revealed that the biogenic particle was influenced by the terrigenous input and was different between dry and wet seasons. Seasonal variations of total flux and relative abundance of living foraminifera were evident in the upper 200 m water column near the Gaoping submarine canyon. Therefore, the seasonal variations of living foraminifera might be reflected on the biogenic particle transport in different seasons in the Gaoping submarine canyon.
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