1,032 research outputs found
Project Management for E-Commerce Businesses
Companies implement different framework and strategies while developing a website. They invest a large amount of money in assessing the prospective market. Therefore, it becomes crucial to analyze the various steps that are important for a good project management of websites. The Ecommerce business world is much more complex. The companies now need to react quickly to global challenges and changing business environments. The research aims to answer and define the best project management techniques to keep the website running in the controlled and complex project environment
Development of an Analysis and Design Optimization Framework for Marine Propellers
In this thesis, a framework for the analysis and design optimization of ship propellers is developed. This framework can be utilized as an efficient synthesis tool in order to determine the main geometric characteristics of the propeller but also to provide the designer with the capability to optimize the shape of the blade sections based on their specific criteria.
A hybrid lifting-line method with lifting-surface corrections to account for the three-dimensional flow effects has been developed. The prediction of the correction factors is achieved using Artificial Neural Networks and Support Vector Regression. This approach results in increased approximation accuracy compared to existing methods and allows for extrapolation of the correction factor values. The effect of viscosity is implemented in the framework via the coupling of the lifting line method with the open-source RANSE solver OpenFOAM for the calculation of lift, drag and pressure distribution on the blade sections using a transition κ-ω SST turbulence model.
Case studies of benchmark high-speed propulsors are utilized in order to validate the proposed framework for propeller operation in open-water conditions but also in a ship’s wake
The Role of Body Image, Dieting, Self-Esteem and Binge Eating in Health Behaviors
Society’s obsession with an idealized thin body type has led to many individuals to seek several different, often harmful, methods to reach their body goals. Current research shows links between body image and self-esteem as well as that between dieting and binge eating-with many researchers finding that extreme dieting can lead to binge eating. The aim of this research was to assess the relationships between body image, dieting, binge eating and self-esteem to understand the ways these factors interact with each other. For this purpose, 60 female participants aged 18-26 years were recruited from Eastern Illinois University and asked to fill out four surveys measuring body image, dieting, binge eating and self-esteem. Results of the surveys suggest that under the certain circumstances, the relationship between body image and dieting was mediated by self-esteem. Furthermore, the relationship between dieting and self-esteem was mediated by binge eating
Stable gene transfer of CCR5 and CXCR4 siRNAs by sleeping beauty transposon system to confer HIV-1 resistance
<p>Abstract</p> <p>Background</p> <p>Thus far gene therapy strategies for HIV/AIDS have used either conventional retroviral vectors or lentiviral vectors for gene transfer. Although highly efficient, their use poses a certain degree of risk in terms of viral mediated oncogenesis. Sleeping Beauty (SB) transposon system offers a non-viral method of gene transfer to avoid this possible risk. With respect to conferring HIV resistance, stable knock down of HIV-1 coreceptors CCR5 and CXCR4 by the use of lentiviral vector delivered siRNAs has proved to be a promising strategy to protect cells from HIV-1 infection. In the current studies our aim is to evaluate the utility of SB system for stable gene transfer of CCR5 and CXCR4 siRNA genes to derive HIV resistant cells as a first step towards using this system for gene therapy.</p> <p>Results</p> <p>Two well characterized siRNAs against the HIV-1 coreceptors CCR5 and CXCR4 were chosen based on their previous efficacy for the SB transposon gene delivery. The siRNA transgenes were incorporated individually into a modified SB transfer plasmid containing a FACS sortable red fluorescence protein (RFP) reporter and a drug selectable neomycin resistance gene. Gene transfer was achieved by co-delivery with a construct expressing a hyperactive transposase (HSB5) into the GHOST-R3/X4/R5 cell line, which expresses the major HIV receptor CD4 and and the co-receptors CCR5 and CXCR4. SB constructs expressing CCR5 or CXCR4 siRNAs were also transfected into MAGI-CCR5 or MAGI-CXCR4 cell lines, respectively. Near complete downregulation of CCR5 and CXCR4 surface expression was observed in transfected cells. During viral challenge with X4-tropic (NL4.3) or R5-tropic (BaL) HIV-1 strains, the respective transposed cells showed marked viral resistance.</p> <p>Conclusion</p> <p>SB transposon system can be used to deliver siRNA genes for stable gene transfer. The siRNA genes against HIV-1 coreceptors CCR5 and CXCR4 are able to downregulate the respective cell surface proteins and thus confer resistance against viral infection by restricting viral entry. These studies have demonstrated for the first time the utility of the non-viral SB system in conferring stable resistance against HIV infection and paved the way for the use of this system for HIV gene therapy studies.</p
Structure and Stability of the Indian Power Transmission Network
We present the study on the Indian power transmission network using the
framework of a complex network and quantify its structural properties. For
this, we build the network structure underlying the Indian power grid, using
two of its most prevalent power lines. We construct an equivalent model of an
exponential network and study its structural changes with changes in two
parameters related to redundancy and dead-ends. Then we analyze its stability
against cascading failures by varying these two parameters using the link
failure model. This helps to gain insight into the relation of network topology
to its stability, and indicates how the optimum choice of these parameters can
result in a power grid structure with minimum failed links. We apply the same
model to study the robustness of the Indian power grid against such failures.
In this case, we find that when a link connected to a generator fails, it
results in a cascade that spreads in the grid until it is split into two
separate stable clusters of generators and consumers, with over one-third of
its nodes nonfunctionaComment: 19 pages, 11 figure
J021659-044920: a relic giant radio galaxy at z ~ 1.3
We report the discovery of a relic Giant Radio Galaxy (GRG) J021659-044920 at
redshift that exhibits large-scale extended, nearly co-spatial,
radio and X-ray emission from radio lobes, but no detection of Active Galactic
Nuclei core, jets and hotspots. The total angular extent of the GRG at the
observed frame 0.325 GHz, using Giant Metrewave Radio Telescope observations is
found to be 2.4 arcmin, that corresponds to a total projected linear
size of 1.2 Mpc. The integrated radio spectrum between 0.240 and 1.4 GHz
shows high spectral curvature ( 1.19) with sharp steepening above
0.325 GHz, consistent with relic radio emission that is 8
10 yr old. The radio spectral index map between observed frame 0.325 and
1.4~GHz for the two lobes varies from 1.4 to 2.5 with the steepening trend from
outer-end to inner-end, indicating backflow of plasma in the lobes. The
extended X-ray emission characterized by an absorbed power-law with photon
index 1.86 favours inverse-Compton scattering of the Cosmic Microwave
Background (ICCMB) photons as the plausible origin. Using both X-ray and radio
fluxes under the assumption of ICCMB we estimate the magnetic field in the
lobes to be 3.3 G. The magnetic field estimate based on energy
equipartition is 3.5 G. Our work presents a case study of a rare
example of a GRG caught in dying phase in the distant Universe.Comment: 10 pages, 5 figures, 3 tables. Published in MNRAS. Corrected typos
and added a referenc
From brain to earth and climate systems: Small-world interaction networks or not?
We consider recent reports on small-world topologies of interaction networks
derived from the dynamics of spatially extended systems that are investigated
in diverse scientific fields such as neurosciences, geophysics, or meteorology.
With numerical simulations that mimic typical experimental situations we have
identified an important constraint when characterizing such networks:
indications of a small-world topology can be expected solely due to the spatial
sampling of the system along with commonly used time series analysis based
approaches to network characterization
Progesterone significantly enhances the mobility of boar spermatozoa
Progesterone released from the cumulus cells of the oocyte causes a number of physiological responses in human sperm cells including hyperactivation, acrosome reaction and chemotaxis. We employed a validated sperm mobility assay, which involves measuring the ability of sperm to penetrate an inert cell separation solution over time, to assess the ability of progesterone to enhance the mobility of boar spermatozoa. Cells maximally penetrate the solution over 50 minutes. 100nM progesterone significantly (P = 0.01) increased the mobility of non-capacitated sperm cells causing a doubling in the rate at which the cells penetrated through the cell separation solution (control half maximal penetration rate [Km] = 18.0±2.2; +100nM progesterone Km = 8.8±0.8min). Similarly, capacitated cells penetrated at a rate (Km = 19.2±3.0 min) not significantly different from non-capacitated cells and 100nM progesterone also significantly increased the rate of penetration of capacitated cells (Km = 9.5±1.0 min, P<0.05). The T-type voltage gated calcium channel blocker mibefradil (30mM) significantly inhibited both the control and progesterone enhanced mobility in non-capacitated and capacitated sperm. Only capacitated cells showed a significant increase in the acrosome reaction in response to 100nM progesterone (control non-reacted = 75±4%, +100nM progesterone non-reacted = 47±10%). Western blot analysis confirmed that there was an increase in the total protein tyrosine phosphorylation levels in capacitated cells. In conclusion, we have demonstrated that 100nM progesterone accelerates the mobility of boar sperm cells through an inert cell separation solution in an extracellular calcium dependent manner
Hawkes process as a model of social interactions: a view on video dynamics
We study by computer simulation the "Hawkes process" that was proposed in a
recent paper by Crane and Sornette (Proc. Nat. Acad. Sci. USA 105, 15649
(2008)) as a plausible model for the dynamics of YouTube video viewing numbers.
We test the claims made there that robust identification is possible for
classes of dynamic response following activity bursts. Our simulated timeseries
for the Hawkes process indeed fall into the different categories predicted by
Crane and Sornette. However the Hawkes process gives a much narrower spread of
decay exponents than the YouTube data, suggesting limits to the universality of
the Hawkes-based analysis.Comment: Added errors to parameter estimates and further description. IOP
style, 13 pages, 5 figure
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