148 research outputs found
Comparison of existing aneurysm models and their path forward
The two most important aneurysm types are cerebral aneurysms (CA) and
abdominal aortic aneurysms (AAA), accounting together for over 80\% of all
fatal aneurysm incidences. To minimise aneurysm related deaths, clinicians
require various tools to accurately estimate its rupture risk. For both
aneurysm types, the current state-of-the-art tools to evaluate rupture risk are
identified and evaluated in terms of clinical applicability. We perform a
comprehensive literature review, using the Web of Science database. Identified
records (3127) are clustered by modelling approach and aneurysm location in a
meta-analysis to quantify scientific relevance and to extract modelling
patterns and further assessed according to PRISMA guidelines (179 full text
screens). Beside general differences and similarities of CA and AAA, we
identify and systematically evaluate four major modelling approaches on
aneurysm rupture risk: finite element analysis and computational fluid dynamics
as deterministic approaches and machine learning and assessment-tools and
dimensionless parameters as stochastic approaches. The latter score highest in
the evaluation for their potential as clinical applications for rupture
prediction, due to readiness level and user friendliness. Deterministic
approaches are less likely to be applied in a clinical environment because of
their high model complexity. Because deterministic approaches consider
underlying mechanism for aneurysm rupture, they have improved capability to
account for unusual patient-specific characteristics, compared to stochastic
approaches. We show that an increased interdisciplinary exchange between
specialists can boost comprehension of this disease to design tools for a
clinical environment. By combining deterministic and stochastic models,
advantages of both approaches can improve accessibility for clinicians and
prediction quality for rupture risk.Comment: 46 pages, 5 figure
Water and Development: An Evaluation of World Bank Support, 1997-2007, Volume 1
The Independent Evaluation Group at the World Bank has evaluated a decade of the Bank's water lending and grants in terms of overall shifts in the water portfolio and project performance, as well as successes and failures in addressing water resource management, environment, water use and service delivery, and institutions and water. The Bank increased its lending for water during the period and has generally seen improvements in project performance; however, IWRM has made limited progress in client countries, environmental restoration has been underemphasized by the Bank, sanitation needs much greater attention, and support for institutional reform and capacity building has had limited success
Doctor of Philosophy
dissertationThe rapidly decreasing of costs of sequencing is revolutionizing genetics. Two applications of next-generation sequencing data are of particular importance in this regard. First, high-throughput sequencing now offers a fast and inexpensive means to investigate the genomes and genetics of nonmodel organisms. Second, human personalgenomics data offer a unique opportunity for discovering the genetic basis of human traits and diseases. My PhD research has focused on developing computational methods to study genetics using next-generation sequencing data. In the first chapter of my thesis, I present a series of genome-based studies of the venomous cone snail Conus bullatus, a source of pharmaceutically important small cysteine-rich peptides called conopeptides or conotoxins. Using high-coverage transcriptome sequence from its venom duct together with low-coverage genomic reads, I have developed new methods to characterize key genomic traits in the absence of a complete reference genome, including genome size, sequence diversity, repeat content and mobile element densities. I have also developed an in silico transcriptomics pipeline for conotoxin discovery, and have used it to identify novel conotoxins as well as candidate enzymes that are likely to be involved in the posttranslational processing of conotoxins. In the second and the third chapters of my thesis, I describe a probabilistic disease-gene search algorithm VAAST (the Variant Annotation, Analysis and Search ! ! Tool) for finding damaged genes and their disease-causing variants; I also describe a powerful new extension to the original code-base called VAAST 2.0. In these chapters, I demonstrate that VAAST is both an accurate rare Mendelian disease-gene finder and a powerful means for identifying genes and alleles underlying common diseases. I have also carried systematic population-genetic simulations in order to benchmark the performance of VAAST and VAAST 2.0 under different genetic scenarios, and these demonstrate that VAAST 2.0 is the most robust and broadly applicable method available today for identification of genes involved in common genetic diseases such as breast cancer, hypertriglyceridemia and Crohn disease
Morphology parameters for intracranial aneurysm rupture risk assessment
OBJECTIVEâThe aim of this study is to identify image-based morphological parameters that
correlate with human intracranial aneurysm (IA) rupture.
METHODSâFor 45 patients with terminal or sidewall saccular IAs (25 unruptured, 20 ruptured),
three-dimensional geometries were evaluated for a range of morphological parameters. In addition
to five previously studied parameters (aspect ratio, aneurysm size, ellipticity index, nonsphericity
index, and undulation index), we defined three novel parameters incorporating the parent vessel
geometry (vessel angle, aneurysm [inclination] angle, and [aneurysm-to-vessel] size ratio) and
explored their correlation with aneurysm rupture. Parameters were analyzed with a two-tailed
independent Student's t test for significance; significant parameters (P < 0.05) were further examined
by multivariate logistic regression analysis. Additionally, receiver operating characteristic analyses
were performed on each parameter.
RESULTSâStatistically significant differences were found between mean values in ruptured and
unruptured groups for size ratio, undulation index, nonsphericity index, ellipticity index, aneurysm
angle, and aspect ratio. Logistic regression analysis further revealed that size ratio (odds ratio, 1.41;
95% confidence interval, 1.03â1.92) and undulation index (odds ratio, 1.51; 95% confidence interval,
1.08â2.11) had the strongest independent correlation with ruptured IA. From the receiver operating
characteristic analysis, size ratio and aneurysm angle had the highest area under the curve values of
0.83 and 0.85, respectively.
CONCLUSIONâSize ratio and aneurysm angle are promising new morphological metrics for IA
rupture risk assessment. Because these parameters account for vessel geometry, they may bridge the
gap between morphological studies and more qualitative location-based studies
Variability and decadal trends in the Isfjorden (Svalbard) ocean climate and circulation â An indicator for climate change in the European Arctic
Isfjorden, a broad Arctic fjord in western Spitsbergen, has shown significant changes in hydrography and inflow of Atlantic Water (AW) the last decades that only recently have been observed in the Arctic Ocean north of Svalbard. Variability and trends in this fjordâs climate and circulation are therefore analysed from observational and reanalysis data during 1987 to 2017. Isfjorden experienced a shift in summer ocean structure in 2006, from AW generally in the bottom layer to AW (with increasing thickness) higher up in the water column. This shift, and a concomitant shift to less fast ice in Isfjorden are linked to positive trends in the mean sea surface temperature (SST) and volume weighted mean temperature (VT) in winter (SSTw/VTw: 0.7 ± 0.1/0.9 ± 0.3 °C 10 yrâ1) and summer (SSTS/VTS: 0.7 ± 0.1/0.6 ± 0.1 °C 10 yrâ1). Hence, the local mean air temperature shows similar trends in winter (1.9 ± 0.4 °C 10 yrâ1) and summer (0.7 ± 0.1 °C 10 yrâ1). Positive trends in volume weighted mean salinity in winter (0.21 ± 0.06 10 yrâ1) and summer (0.07 ± 0.05 10 yrâ1) suggest increased AW advection as a main reason for Isfjordenâs climate change. Local mean air temperature correlates significantly with sea ice cover, SST, and VT, revealing the fjordâs impact on the local terrestrial climate. In line with the shift in summer ocean structure, Isfjorden has changed from an Arctic type fjord dominated by Winter Deep and Winter Intermediate thermal and haline convection, to a fjord dominated by deep thermal convection of Atlantic type water (Winter Open). AW indexes for the mouth and Isfjorden proper show that AW influence has been common in winter over the last decade. Alternating occurrence of Arctic and Atlantic type water at the mouth mirrors the geostrophic control imposed by the Spitsbergen Polar Current (carrying Arctic Water) relative to the strength of the Spitsbergen Trough Current (carrying AW). During high AW impact events, Atlantic type water propagates into the fjord according to the cyclonic circulation along isobaths corresponding to the winter convection. Tides play a minor role in the variance in the currents, but are important in the side fjords where exchange with the warmer Isfjorden proper occurs in winter. This study demonstrates that Isfjorden and its ocean climate can be used as an indicator for climate change in the Arctic Ocean. The used methods may constitute a set of helpful tools for future studies also outside the Svalbard Archipelago.publishedVersio
Water in the Arab World
This volume is intended to serve as a water handbook. It represents the collective knowledge about water resources management acquired over recent years, both within the World Bank water team and with counterparts working in the Arab countries of North Africa and the Middle East (MNA). The chapters offer a cornucopia of ideas and themes. Some chapters are based on background papers prepared for the 2007 "MNA Development Report on Water." Others draw on sector work prepared at the request of client countries. Yet others summarize observations based on study tours or other learning events sponsored by the World Bank. Upon reviewing this lodestone of embedded knowledge, we realized that bringing together our observations and analyses could serve a useful purpose for public officials, other practitioners, academics, and students who are interested in learning more about the complexities of managing water resources management in one of the driest parts of the world
Ontology learning for the semantic deep web
Ontologies could play an important role in assisting users in their search for Web pages. This dissertation considers the problem of constructing natural ontologies that support users in their Web search efforts and increase the number of relevant Web pages that are returned. To achieve this goal, this thesis suggests combining the Deep Web information, which consists of dynamically generated Web pages and cannot be indexed by the existing automated Web crawlers, with ontologies, resulting in the Semantic Deep Web. The Deep Web information is exploited in three different ways: extracting attributes from the Deep Web data sources automatically, generating domain ontologies from the Deep Web automatically, and extracting instances from the Deep Web to enhance the domain ontologies. Several algorithms for the above mentioned tasks are presented. Lxperimeiital results suggest that the proposed methods assist users with finding more relevant Web sites. Another contribution of this dissertation includes developing a methodology to evaluate existing general purpose ontologies using the Web as a corpus. The quality of ontologies (QoO) is quantified by analyzing existing ontologies to get numeric measures of how natural their concepts and their relationships are. This methodology was first applied to several major, popular ontologies, such as WordNet, OpenCyc and the UMLS. Subsequently the domain ontologies developed in this research were evaluated from the naturalness perspective
SIMULATING CONSUMABLE ORDER FULFILLMENT VIA ADDITIVE MANUFACTURING TECHNOLOGIES
Operational availability of naval aircraft through material readiness is critical to ensuring combat power. Supportability of aircraft is a crucial aspect of readiness, influenced by several factors including access to 9B Cognizance Code (COG) aviation consumable repair parts at various supply echelons. Rapidly evolving additive manufacturing (AM) technologies are transforming supply chain dynamics and the traditional aircraft supportability construct. As of June 2022, there are 595 AM assets within the Navyâs inventoryâall for research and development purposes. This report simulates 9B COG aviation consumable fulfillment strategies within the U.S. Indo-Pacific sustainment network for a three-year span, inclusive of traditional supply support avenues and a developed set of user-variable capability inputs. Simulated probabilistic demand configurations are modeled from historical trends that exploit a heuristic methodology to assign a âprintabilityâ score to each 9B COG requirement, accounting for uncertainty, machine failure rates, and other continuous characteristics of the simulated orders. The results measure simulated lead time across diverse planning horizons in both current and varied operationalized AM sustainment network configurations. This research indicates a measurable lead time reduction of approximately 10% across all 9B order lead times when AM is employed as an order fulfillment source for only 0.5% of orders.NPS Naval Research ProgramThis project was funded in part by the NPS Naval Research Program.Lieutenant Commander, United States NavyApproved for public release. Distribution is unlimited
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