• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 638
  • 218
  • 133
  • 77
  • 42
  • 39
  • 20
  • 13
  • 10
  • 9
  • 8
  • 8
  • 7
  • 5
  • 5
  • Tagged with
  • 1454
  • 174
  • 165
  • 163
  • 137
  • 114
  • 100
  • 95
  • 93
  • 87
  • 70
  • 70
  • 67
  • 66
  • 66
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Micro PIV and Numerical Investigation of a Micro-Couette Blood Flow

Mehri, Rym 22 June 2012 (has links)
The purpose of this thesis is to design a physical microchannel model for micro-Couette blood flow that provides constant and controlled conditions to study and analyze Red Blood Cell (RBC) aggregation. The innovation of this work is that the Couette blood flow is created by the motion of a second fluid with different properties, thereby entraining the blood. The experimental work is coupled with three-dimensional numerical simulations performed using a research Computational Fluid Dynamic (CFD) Solver, Nek5000, based on the spectral element method, while the experiments are conducted using a micro Particle Image Velocimetry (μPIV) system with a double frame CCD camera and an inverted laser imaging microscope. The design of the channel (150 × 33 μm and 170 × 64 μm microchannels) is based on several parameters determined numerically, such as the velocity and viscosity ratios and the degree of miscibility between the fluids, and the resulting configurations are fabricated in the laboratory using standard photolithography methods. The microchannel designed numerically is then tested experimentally, first, with a Newtonian fluid (glycerol), then with RBC suspensions to be compared to the simulations results. It was found that, numerically, using a velocity ratio of 4 between the two fluids, a third of the channel thickness corresponds to the blood layer. Within that range, it can be concluded, that the velocity profile of the blood layer is approximately linear as confirmed by experimental tests, resulting in the desired profile to study RBC aggregation in controlled conditions. The effect of several parameters, such as the hematocrit and the shear rate, on the RBC aggregates and the velocity profile is investigated, through experiments on the RBC suspensions. The final goal of this research is to ensure the compatibility of the results between the experiments and the Newtonian numerical model for several ranges of shear rate with the future intention of finding an accurate method to be able to quantitatively analyze aggregates and determine the number of RBC in each aggregate depending on the flow conditions (the shear rate).
182

Utilization of Dynamic Attributes in Resource Discovery for Network Virtualization

Amarasinghe, Heli 16 July 2012 (has links)
The success of the internet over last few decades has mainly depended on various infrastructure technologies to run distributed applications. Due to diversification and multi-provider nature of the internet, radical architectural improvements which require mutual agreement between infrastructure providers have become highly impractical. This escalating resistance towards the further growth has created a rising demand for new approaches to address this challenge. Network virtualization is regarded as a prominent solution to surmount these limitations. It decouples the conventional Internet service provider’s role into infrastructure provider (InP) and service provider (SP) and introduce a third player known as virtual network Provider (VNP) which creates virtual networks (VNs). Resource discovery aims to assist the VNP in selecting the best InP that has the best matching resources for a particular VN request. In the current literature, resource discovery focuses mainly on static attributes of network resources highlighting the fact that utilization on dynamic attributes imposes significant overhead on the network itself. In this thesis we propose a resource discovery approach that is capable of utilizing the dynamic resource attributes to enhance the resource discovery and increase the overall efficiency of VN creation. We realize that recourse discovery techniques should be fast and cost efficient, enough to not to impose any significant load. Hence our proposed scheme calculates aggregation values of the dynamic attributes of the substrate resources. By comparing aggregation values to VN requirements, a set of potential InPs is selected. The potential InPs satisfy basic VN embedding requirements. Moreover, we propose further enhancements to the dynamic attribute monitoring process using a vector based aggregation approach.
183

Eliciting and Aggregating Forecasts When Information is Shared

Palley, Asa January 2016 (has links)
<p>Using the wisdom of crowds---combining many individual forecasts to obtain an aggregate estimate---can be an effective technique for improving forecast accuracy. When individual forecasts are drawn from independent and identical information sources, a simple average provides the optimal crowd forecast. However, correlated forecast errors greatly limit the ability of the wisdom of crowds to recover the truth. In practice, this dependence often emerges because information is shared: forecasters may to a large extent draw on the same data when formulating their responses. </p><p>To address this problem, I propose an elicitation procedure in which each respondent is asked to provide both their own best forecast and a guess of the average forecast that will be given by all other respondents. I study optimal responses in a stylized information setting and develop an aggregation method, called pivoting, which separates individual forecasts into shared and private information and then recombines these results in the optimal manner. I develop a tailored pivoting procedure for each of three information models, and introduce a simple and robust variant that outperforms the simple average across a variety of settings.</p><p>In three experiments, I investigate the method and the accuracy of the crowd forecasts. In the first study, I vary the shared and private information in a controlled environment, while the latter two studies examine forecasts in real-world contexts. Overall, the data suggest that a simple minimal pivoting procedure provides an effective aggregation technique that can significantly outperform the crowd average.</p> / Dissertation
184

Effects of Prickly Pear Nectar on Blood Glucose and Platelet Aggregation in a Type 2 Model of Diabetes

Russell, Danielle, Ritz, Patricia January 2009 (has links)
Class of 2009 Abstract / OBJECTIVES: An estimated 26.3 million Americans have Diabetes Mellitus (DM). Currently six classes of agents are approved for the treatments of Type 2 DM. Problems with current options have led to searches for new medications and adjunctive therapy. Prickly pear (Opuntia species) has been traditionally used by Mexicans and Pima Indians for the treatment of DM. This is a retrospective analysis of data obtained from a randomized placebo-controlled prospective experiment in 28 Type 2 DM rodents (ZDF). There were 2 negative control groups which consisted of non-DM rodents and ZDFs; each receiving water. The positive control group consisted of ZDFs who received rosiglitazone 4.75 mg/kg/day. The treatment group consisted of ZDFs who received 5-10 mL/kg/dose of Opuntia ficus indica (Jugo De Nopal) liquid, given twice daily. Weight, blood glucose and platelet aggregation were recorded and analyzed. At baseline, there were no significant differences in weight or blood glucose among ZDF groups. The lean control rodents had significantly lower blood glucose compared to the ZDF rodents (p<0.001). Treatment with Jugo de Nopal resulted in a statistically significant reduction in blood glucose (p<0.001), with a mean decrease in blood glucose of 7%. All treatment groups demonstrated a significant weight gain, however, the prickly pear group had significantly less weight gain than the rosiglitazone group (p=0.028). CONCLUSIONS: There was not a significant difference among the treatment groups with regard to platelet responsiveness. Further studies are necessary to determine the efficacy of prickly pear as a blood glucose lowering agent.
185

Modulating the aggregation of alpha-synuclein and prion protein with small molecules.

Fonseca Ornelas, Luis Eduardo 14 February 2016 (has links)
No description available.
186

Algoritmus pro automatizovanou kartografickou generalizaci shluků budov metodou agregace / Algorithm for automated building simplification using aggregation

Svobodová, Jana January 2012 (has links)
Algorithm for automated building simplification using aggregation Abstract Diploma thesis deals with automated cartographic generalization. The main aim is to propose a new generalization algorithm for building aggregation. The first part brings summary of existing algorithms for building aggre- gation. Then the new algorithm is presented: at first, auxiliary data structu- res and algorithms are presented, then cartographic and geometric require- ments are defined. New algorithm is based on the principle of straight skeleton construction. Outer vertices are removed from constructed straight skeletons and those structures are aggregated. The aggregated polygon is reconstructed from ag- gregated structures. The second part is focused on implementation and results evaluation. The algorithm is implemented using open-source libraries CGAL, Boost and Shapelib. The results and confrontation with SW ArcGIS are discus- sed in conclusion of the thesis. 1
187

Samoorganizace a optické vlastnosti malých molekulárních agregátů / Selforganization and optical properties of small molecular aggregates

Sláma, Vladislav January 2013 (has links)
The work deals with the description of carotenoid aggregation in water solutions. The main interactions which are involved in aggregation were analyzed and an efficient way of description of carotenoid aggregation, which leads to a speed up the computation, has been introduced. In addition, two different methods for calculation probability distribution of catotenoids configurations in solutions with variable water concentration were elaborated, and their advantages and disadvantages were discussed. Absorption spectra were calculated from these distributions, and they were compared with the experimental results. The influence of water on formation of different types of aggregates, and its impact on the shape of absorption spectra was also discussed. Results of this study will be used as a base of other, more accurate, description of carotenoids aggregation, which will include other weaker interactions between carotenoids.
188

Localization and Mutational Analysis of the Nuclear and Aggregation-Prone Ime4 Protein in Saccharomyces cerevisiae

Dehon, Patricia M 15 December 2012 (has links)
In Saccharomyces cerevisiae, Ime4 is a protein that is induced during meiosis and has a primary role in regulating sporulation in starving diploids. One function of Ime4 is methylation of adenosine residues within mRNA transcripts. Recent studies have shown Ime4 to be induced in haploids during the mating response, although its role in mating has not been determined. In this report, I identify the subcellular localization of Ime4 during the mating response through treatment with alpha factor. A plasmid containing IME4-GFP under the control of the medium strength promoter CYC1 was created in order to express the protein in a controlled manner. Lastly, mutational analysis was conducted to determine which regions of the protein were necessary for its nuclear localization, aggregation, and sporulation function.
189

Social and Basking Behaviors in Juvenile, Captive-Raised Northern Diamondback Terrapins (Malaclemys terrapin terrapin)

Rife, Alexis January 2007 (has links)
Thesis advisor: Eric Strauss / Thesis advisor: Peter Auger / Northern Diamondback Terrapin (Malaclemys terrapin terrapin) hatchlings from the Great Marsh of Barnstable, Massachusetts on Cape Cod were studied as part of a headstarting program at Boston College. Although headstarting programs are relatively common methods to revive wild turtle populations, concern exists over the ability of headstarted terrapins to exhibit normal behavior when released into the wild. Observations of terrapins in the wild and in the laboratory suggest that terrapins are highly social and that these social interactions are modulated by kinship relations. This study investigated the social behavior of juvenile terrapins while they were basking on a restricted site. Groups of familiar kin and nonkin, and unfamiliar kin and nonkin were tested. Familiar kin were found to bask in larger groups and showed a willingness to share the limited basking site. Unfamiliar nonkin also interacted, but were more aggressive. Unfamiliar kin and familiar nonkin were not distinguishable in their behaviors. These results suggest that terrapins form social groups based on both familiarity and relatedness. Learning how captive headstarted terrapins form social groups and share resources may provide key information for their survival and recovery efforts in Massachusetts. / Thesis (BS) — Boston College, 2007. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Biology. / Discipline: College Honors Program.
190

The Driving Forces of Peptide Aggregation: A Study of the Yeast Sup35 Prion Fragment GNNQQNY

Lebo, Kevin January 2008 (has links)
Thesis advisor: Jianmin Gao / Protein aggregation can be highly detrimental to organisms, and has been associated with diseases including Alzheimer's, Huntington's, type II diabetes, and transmissible spongiform encephalopathies such as Mad Cow disease. There is no single amino acid sequence responsible for aggregation into amyloid-like structures, but rather a large range of amyloidogenic peptides have been discovered. A fragment of the yeast Sup35 prion, GNNQQNY, has been found to aggregate using a "dry, steric zipper" structure. This study looks at mutants of GNNQQNY in order to elucidate the exact contributions of various amino acids to the aggregation process. / Thesis (BS) — Boston College, 2008. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Chemistry. / Discipline: College Honors Program.

Page generated in 0.097 seconds