243 research outputs found
The etiology of esophageal cancer in high- and low- risk areas of Jiangsu province, China
No full text [Background]Esophageal cancer (EC) remains one of the most common and fatal malignancies worldwide. The geographic variation in EC occurrence is striking, and China is an area with one of the highest incidences of EC. A number of epidemiological studies have been conducted toward EC in the past decades, results suggested that tobacco smoking, alcohol drinking, unhealthy dietary factors and chronic injuries of the esophageal mucosa are important in the development of this disease. Genetic polymorphisms in enzymes involved in metabolism of carcinogens may also influence individual susceptibility. However, the effects of major lifestyle and hereditary risk factors on the development of EC remain poorly understood in China. Moreover, little attention has been paid to the etiological heterogeneity between similar areas with great risk gradient. [Methods]From 2003 to 2007, a large population-based case-control study of EC has been conducted in a selected high-risk area and a selected low-risk area of Jiangsu Province, one of the highest cancer incidence areas in China. In total, 1,520 cases and 3,879 controls were recruited. In this thesis, we evaluated the role of major lifestyle factors such as tobacco smoking, alcohol drinking and dietary factors, as well as inherited determinants including family history of cancer and genetic polymorphisms of alcohol-metabolizing related genes on the risk of EC. In addition, we investigated how much of the risk gradient between two areas could be explained by variation in the distributions of major risk factors. [Results] Tobacco smoking and alcohol drinking moderately increased the risk of EC, while the positive associations were only found among men but not among women. Dietary factors were observed to play important roles in the development of EC. Specific dietary habits i.e., fast eating speed, and hot eating and/or drinking substantially elevated EC risk and could explain more than 20% of EC cases each. High intake of salty foods and fried foods, low consumption of raw garlic were also observed to increase the risk of EC. In addition to environmental and lifestyle factors, we confirmed that a positive family history can significantly increase EC risk, and found the inheritance may modify the effect of some unhealthy lifestyles. Moreover, we further explored the relationship between EC and single nucleotide polymorphismsof ADH1B, ADH1C and ALDH2 genes. Results showed that the slow metabolizing ADH1B G allele, ADH1C G allele and ALDH2 A allele significantly increased EC risk among moderate-to-heavy alcohol drinkers, and a significant interaction was observed between ALDH2 gene and alcohol consumption. Lastly, we found that more than 60% of EC cases could be attributable to major lifestyle risk factors in the study population; furthermore, dissimilar distribution of several lifestyle factors, together with variations of hereditary factors may be largely responsible for the incidence difference between two study areas. [Conclusion]The findings in this thesis confirm that unhealthy lifestyles including smoking, alcohol drinking and some dietary factors are the predominant risk factors of EC in China, and a large proportion of incidence difference between regions at varying risk could be attributed to the different prevalence of lifestyle factors. As most of the identified risk factors are modifiable, these could be translated into risk reduction prevention programs in China, and a substantial proportion of new EC cases are expected to be prevented by eliminating or avoiding these risk factors in the population. </p
Numerical Analysis and Modelling of Transmission Systems for Hybrid Electric Vehicles and Electric Vehicles
No full textInterest in hybrid electric vehicles (HEVs) and electric vehicles (EVs) has
increased rapidly over recent years from both industrial and academic viewpoints
due to increasing concerns about environmental pollution and global oil usage. In
the automotive sector, huge efforts have been invested in vehicle technology to
improve efficiency and reduce carbon emissions with, for example, hybrid and
electric vehicles. This thesis focuses on one design area of these vehicles – the
transmission – with the aim of investigating the potential benefits of improved
transmissions for HEVs and EVs.
For HEVs, a novel transmission developed by Nexxtdrive based on a twin
epicyclic design is analysed using a matrix method and its performance is
compared with the more common single epicyclic arrangement used successfully
in the Toyota Prius. Simulation models are then used to compare the performance
of a typical HEV passenger car fitted with these two transmissions over standard
driving cycles. The conclusion is that the twin epicyclic offers substantial
improvements of up to 20% reduction in energy consumption, though the benefits
are sensitive to the driving cycle used.
For EVs, most designs to date have used a single fixed ratio transmission, and
surprisingly little research has explored whether multi-geared transmissions offer
any benefits. The research challenge is whether it is possible to optimise the
usage of the electric motor in its region of high efficiency by controlling the
transmission. Simulation results of two EV examples confirm that energy
consumption benefits are indeed achievable – of between 7 and 14% depending
on the driving cycle.
Overall, the original aspects of this work – the analysis and modelling the twin
epicyclic gearbox; the analysis and modelling the twin epicyclic system in a vehicle
and a comparison of the results with single epicyclic system; and the analysis and
modelling of EVs with and without a transmission system of varying levels of
complexity – have shown that there are worthwhile performance benefits from
using improved transmission designs for low carbon vehicles
Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Dynamical Evidence of a Spiral-Arm-Driving and Gap-Opening Protoplanet from SAO 206462 Spiral Motion
No full textIn the early stages of planetary system formation, young exoplanets gravitationally interact with their surrounding environments and leave observable signatures on protoplanetary disks. Among these structures, a pair of nearly symmetric spiral arms can be driven by a giant protoplanet. For the double-spiraled SAO 206462 protoplanetary disk, we obtained three epochs of observations spanning 7 yr using the Very Large Telescope’s SPHERE instrument in near-infrared J-band polarized light. By jointly measuring the motion of the two spirals at three epochs, we obtained a rotation rate of −0.°85±0.°05yr−1. This rate corresponds to a protoplanet at 66±3 au on a circular orbit dynamically driving both spirals. The derived location agrees with the gap in ALMA dust-continuum observations, indicating that the spiral driver may also carve the observed gap. What is more, a dust filament at ∼63 au observed by ALMA coincides with the predicted orbit of the spiral-arm-driving protoplanet. This double-spiraled system is an ideal target for protoplanet imaging
Checklist of the mosses of sub-Saharan Africa
No full text2939 moss taxa are listed for sub-Saharan Africa and adjacent islands, with distribution by country. Each distribution record is supported by a literature reference. The following new combinations are made: Calyptrochaeta cristata (Hedw.) O’Shea, Groutiella elimbata (Thér) O’Shea, Meiothecium undulatum (Ren. & Card.) O’Shea, Orthodontium ruwenzorensis (Thér. & Nav.) O’Shea, Pohlia lacouturei (Thér.) O’Shea, Sematophyllum corticolum (Aongstr.) O’Shea, Sematophyllum dixonii (Thér.) O’Shea, Sematophyllum nanopyxis (Geh.) O’Shea, Sematophyllum rigescens (Card.) O’Shea, and Thamnobryum malgachum (Card.) O’Shea
Draft genome of the filarial nematode parasite Brugia malayi
No full textParasitic nematodes that cause elephantiasis and river blindness threaten hundreds of millions of people in the developing world. We have sequenced the approximately 90 megabase (Mb) genome of the human filarial parasite Brugia malayi and predict approximately 11,500 protein coding genes in 71 Mb of robustly assembled sequence. Comparative analysis with the free-living, model nematode Caenorhabditis elegans revealed that, despite these genes having maintained little conservation of local synteny during approximately 350 million years of evolution, they largely remain in linkage on chromosomal units. More than 100 conserved operons were identified. Analysis of the predicted proteome provides evidence for adaptations of B. malayi to niches in its human and vector hosts and insights into the molecular basis of a mutualistic relationship with its Wolbachia endosymbiont. These findings offer a foundation for rational drug design
The historie of the world, [electronic resource] : in five books. The first. Intreating of the beginning and first ages of the same, from the Creation unto Abraham. The second. Of the times from the birth of Abraham to the destruction of the Temple of Solomon. The third. From the destruction of Jerusalem to the Time of Philip of Macedon. The fourth. From the reign of Philip of Macedon to the establishing of that kingdom in the race of Antigonus. The fifth. From the settled rule of Alexanders successors in the East, untill the Romans (prevailing over all) made conquest of Asia and Macedon. /
No full textWith added engraved title page signed: "Ren. Elstracke sculpsit." and dated 1666; headpieces, initials.Ben Jonson's stanzas "The mind of the front" follows general t.p.Engraved portrait of Raleigh signed: "Sim. Pass. sculp.", "Comp Holland inv."Title page in red and black.Includes indexes.Numerous errors in paging.The [16] leaves of plates include 8 engraved maps (one signed: "Guili. Hole fecit.") mounted as double plates.Reproduction of original in: Birmingham Central Reference Library (Birmingham, England).Wing (2nd ed.)Electronic reproduction
New and interesting Campylopus records from South Africa
No full textNew records are presented based on a collection of Campylopus specimens made by the second author in the Western Cape Province of South Africa. The austral species Campylopus clavatus (R. Brown) Wils. in Hook. and Campylopus vesticaulis Mitt. are reported for the first time for Africa, and Campylopus acuminatus Mitt. var. kirkii (Mitt.) J.-P. Frahm is recorded for the second time for Africa. Campylopus arctocarpus (Hornsch.) Mitt. ssp. madegassus (Besch.) J.-P. Frahm is reported for the first time for the Republic of South Africa, and this is the southernmost record of this species. Campylopus simii Schelpe is not synonymous with C. julaceus Jaeg. ssp. arbogastii (Ren. & Card.) J.-P. Frahm but combined here as new as a variety of C. pilifer Brid
Relative power and sample size analysis on gene expression profiling data
No full textBackground: With the increasing number of expression profiling technologies, researchers today are confronted with choosing the technology that has sufficient power with minimal sample size, in order to reduce cost and time. These depend on data variability, partly determined by sample type, preparation and processing. Objective measures that help experimental design, given own pilot data, are thus fundamental. Results: Relative power and sample size analysis were performed on two distinct data sets. The first set consisted of Affymetrix array data derived from a nutrigenomics experiment in which weak, intermediate and strong PPARα agonists were administered to wild-type and PPARα-null mice. Our analysis confirms the hierarchy of PPARα-activating compounds previously reported and the general idea that larger effect sizes positively contribute to the average power of the experiment. A simulation experiment was performed that mimicked the effect sizes seen in the first data set. The relative power was predicted but the estimates were slightly conservative. The second, more challenging, data set describes a microarray platform comparison study using hippocampal δC-doublecortin-like kinase transgenic mice that were compared to wild-type mice, which was combined with results from Solexa/Illumina deep sequencing runs. As expected, the choice of technology greatly influences the performance of the experiment. Solexa/Illumina deep sequencing has the highest overall power followed by the microarray platforms Agilent and Affymetrix. Interestingly, Solexa/Illumina deep sequencing displays comparable power across all intensity ranges, in contrast with microarray platforms that have decreased power in the low intensity range due to background noise. This means that deep sequencing technology is especially more powerful in detecting differences in the low intensity range, compared to microarray platforms. Conclusion: Power and sample size analysis based on pilot data give valuable information on the performance of the experiment and can thereby guide further decisions on experimental design. Solexa/Illumina deep sequencing is the technology of choice if interest lies in genes expressed in the low-intensity range. Researchers can get guidance on experimental design using our approach on their own pilot data implemented as a BioConductor package, SSPA http://bioconductor.org/packages/release/bioc/html/SSPA.html
The impact of heat waves on mortality.
No full textBACKGROUND: Heat waves have been linked with an increase in mortality, but the associated risk has been only partly characterized. METHODS: We examined this association by decomposing the risk for temperature into a "main effect" due to independent effects of daily high temperatures, and an "added" effect due to sustained duration of heat during waves, using data from 108 communities in the United States during 1987-2000. We adopted different definitions of heat-wave days on the basis of combinations of temperature thresholds and days of duration. The main effect was estimated through distributed lag nonlinear functions of temperature, which account for nonlinear delayed effects and short-time harvesting. We defined the main effect as the relative risk between the median city-specific temperature during heat-wave days and the 75th percentile of the year-round distribution. The added effect was defined first using a simple indicator, and then a function of consecutive heat-wave days. City-specific main and added effects were pooled through univariate and multivariate meta-analytic techniques. RESULTS: The added wave effect was small (0.2%-2.8% excess relative risk, depending on wave definition) compared with the main effect (4.9%-8.0%), and was apparent only after 4 consecutive heat-wave days. CONCLUSIONS: Most of the excess risk with heat waves in the United States can be simply summarized as the independent effects of individual days' temperatures. A smaller added effect arises in heat waves lasting more than 4 days
Multi-Agent Coordination and Control under Information Asymmetry with Applications to Collective Load Transport
No full textabstract: Coordination and control of Intelligent Agents as a team is considered in this thesis.
Intelligent agents learn from experiences, and in times of uncertainty use the knowl-
edge acquired to make decisions and accomplish their individual or team objectives.
Agent objectives are defined using cost functions designed uniquely for the collective
task being performed. Individual agent costs are coupled in such a way that group ob-
jective is attained while minimizing individual costs. Information Asymmetry refers
to situations where interacting agents have no knowledge or partial knowledge of cost
functions of other agents. By virtue of their intelligence, i.e., by learning from past
experiences agents learn cost functions of other agents, predict their responses and
act adaptively to accomplish the team’s goal.
Algorithms that agents use for learning others’ cost functions are called Learn-
ing Algorithms, and algorithms agents use for computing actuation (control) which
drives them towards their goal and minimize their cost functions are called Control
Algorithms. Typically knowledge acquired using learning algorithms is used in con-
trol algorithms for computing control signals. Learning and control algorithms are
designed in such a way that the multi-agent system as a whole remains stable during
learning and later at an equilibrium. An equilibrium is defined as the event/point
where cost functions of all agents are optimized simultaneously. Cost functions are
designed so that the equilibrium coincides with the goal state multi-agent system as
a whole is trying to reach.
In collective load transport, two or more agents (robots) carry a load from point
A to point B in space. Robots could have different control preferences, for example,
different actuation abilities, however, are still required to coordinate and perform
load transport. Control preferences for each robot are characterized using a scalar
parameter θ i unique to the robot being considered and unknown to other robots.
With the aid of state and control input observations, agents learn control preferences
of other agents, optimize individual costs and drive the multi-agent system to a goal
state.
Two learning and Control algorithms are presented. In the first algorithm(LCA-
1), an existing work, each agent optimizes a cost function similar to 1-step receding
horizon optimal control problem for control. LCA-1 uses recursive least squares as
the learning algorithm and guarantees complete learning in two time steps. LCA-1 is
experimentally verified as part of this thesis.
A novel learning and control algorithm (LCA-2) is proposed and verified in sim-
ulations and on hardware. In LCA-2, each agent solves an infinite horizon linear
quadratic regulator (LQR) problem for computing control. LCA-2 uses a learning al-
gorithm similar to line search methods, and guarantees learning convergence to true
values asymptotically.
Simulations and hardware implementation show that the LCA-2 is stable for a
variety of systems. Load transport is demonstrated using both the algorithms. Ex-
periments running algorithm LCA-2 are able to resist disturbances and balance the
assumed load better compared to LCA-1.Dissertation/ThesisMasters Thesis Electrical Engineering 201
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