3,153 research outputs found
RAGE-Based strategies for the control of gene expression
The Cre/loxP site-specific recombinase system evolved within bacteriophage PI as a
mechanism to maintain correct unit copy segregation of the prophage within host
cells. This thesis reports the application of this system to regulate gene expression in
murine cells. To achieve the regulation of gene expression a novel floxed STOP
cassette was designed, constructed and tested in murine embryonic fibroblasts (EF)
and embryonic stem (ES) cells. It was shown that the floxed STOP cassette could be
used successfully to regulate the transcription of the Enhanced Green Fluorescent
Protein (EGFP) marker gene in ES cells. However, no expression of the EGFP gene
could be detected at the protein level and several reasons for this observation are
discussed.The floxed STOP cassette was also utilised in strategies to achieve conditional
expression of the tumour suppressor gene p53. A complex array of biological
functions have been assigned to p53. For example, p53 is known to be involved in
the regulation of apoptosis, multiple cell cycle checkpoints and the onset of
replicative cellular senescence. The development of novel approaches to achieve
conditional p53 expression should be a valuable tool and permit further investigation
into the pleiotropic nature of p53 function. Therefore, the floxed STOP cassette was
used to regulate the expression of a p53 cDNA in p53 null primary EF cells in vitro.
The upregulation of p53 expression after Cre administration was detected, but at a
low frequency, by immunohistochemistry. The response of EF cells to the
expression of p53 in terms of replicative cellular senescence was also characterised,
including the first description of senescence-associated (3-galactosidase expression in
any murine cell. The floxed STOP technology was also used in an attempt to
regulate the expression of the endogenous murine p53 gene in vivo. The successful
integration of the floxed STOP cassette, via an inducible gene targeting strategy, into
the murine p53 locus of ES cells is reported.Two methods were explored to achieve regulated expression of Cre recombinase in
vitro, the novel technology of recombinant adenoviridiae and the identification of
embryonal stem cell differentiation state-specific promoter regulatory sequences.In conclusion, this thesis has explored the feasibility of using Cre/loxP-based
technologies to regulate gene expression. Several test plasmids were constructed and
characterised and all demonstrated that the application of floxed STOP-based
approaches is not as straightforward as suggested by the relatively small body of
literature in this field
Beyond the Fairytale: The Real Story of Homelessness
Childhood memories are important for those who are caught in the confines of poverty and homelessness. This is a qualitative and phenomenological research study with a focus on the narratives of five African American women who were previously homeless. The first research question identified emerging themes. Five main themes were acknowledged: family interactions, education, abuse and violence, nutrition, and the effects of stability in childhood. The two part second research question referred to the negative power of systems that vilify and curtail transformative growth, as well as community input to solve issues of poverty and homelessness. The study was conducted in Saint Paul, Minnesota and four of the five women interviewed received social services from a local day shelter program. Each woman agreed to participate in a three hour-long interview. Data analysis of the interviews revealed that childhood issues carried through to later years. It was important for those interviewed to have the correct problem solving tools to overcome adversity. Usually poverty is defined as the lack of financial resources. It was found that in order to reduce homelessness, society has to broaden the definition to the inability of a person to find correct, current, and useful information that has the means to change their financial and emotional status. The common threads of homelessness and poverty identify the need for governmental entitlement changes. The scourge of poverty can be viewed from a perspective of a challenge that is both feasible and ultimately manageable
Anisotropic scaling of remotely sensed drainage basins: the differential anisotropy scaling technique
International audienceWe investigate the statistical properties of dendritic drainage areas from diverse geological environments (Deception Canyon, Utah and the Loess Plateau, China) using narrow band visible ASTER satellite images. We show that from 240 m to 7680 m, the isotropic (angle integrated) energy spectra E(k) of all the fields closely follow a power law form: E(k)?k?? where k is a wave number and ? a scale invariant exponent. In spite of this good isotropic scaling, images with very similar ?'s and similar isotropic multifractal exponents have distinct textures; we suggest that the differences are primarily due to anisotropy, which is nevertheless scaling. We develop the new "Differential Anisotropy Scaling" technique to characterize this scale-by-scale (differential) anisotropy and we test it on simulated anisotropic scaling fields. The method gives useful characterizations of the scale by scale anisotropy irrespective of whether or not the analyzed field is scaling. When the anisotropy is not too strong, the parameters can be interpreted as scale invariant anisotropy exponents. Viewed as a method of estimating these exponents, it has the advantage of relying on two linear regressions rather than on complex higher dimensional nonlinear ones. When applied to dendritic drainage basins we find that they have distinct anisotropies characterized by differential anisotropy stretching and rotation parameters as well as by a distinct absolute anisotropy at the reference scale of 960 m. Our new method allows us to statistically distinguish, not only between two geologically different drainage basins (the China Loess Plateau and Utah Deception Canyon), but also between different regions of the same China drainage system
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Repercussions of the Atlantic Slave Trade: The Interior of the Bight of Biafra and the African Diaspora
Can the palatability of healthy, satiety-promoting foods increase with repeated exposure during weight loss?
Repeated exposure to sugary, fatty, and salty foods often enhances their appeal. However, it is unknown if exposure influences learned palatability of foods typically promoted as part of a healthy diet. We tested whether the palatability of pulse containing foods provided during a weight loss intervention which were particularly high in fiber and low in energy density would increase with repeated exposure. At weeks 0, 3, and 6, participants (n = 42; body mass index (BMI) 31.2 ± 4.3 kg/m²) were given a test battery of 28 foods, approximately half which had been provided as part of the intervention, while the remaining half were not foods provided as part of the intervention. In addition, about half of each of the foods (provided as part or not provided as part of the intervention) contained pulses. Participants rated the taste, appearance, odor, and texture pleasantness of each food, and an overall flavor pleasantness score was calculated as the mean of these four scores. Linear mixed model analyses showed an exposure type by week interaction effect for taste, texture and overall flavor pleasantness indicating statistically significant increases in ratings of provided foods in taste and texture from weeks 0 to 3 and 0 to 6, and overall flavor from weeks 0 to 6. Repeated exposure to these foods, whether they contained pulses or not, resulted in a ~4% increase in pleasantness ratings. The long-term clinical relevance of this small increase requires further study.T32 AT000815 - NCCIH NIH HH
On two 10th order mock theta identities
We give short proofs of conjectural identities due to Gordon and McIntosh
involving two 10th order mock theta functions.Comment: 5 pages, to appear in the Ramanujan Journa
Large Scale Structures a Gradient Lines: the case of the Trkal Flow
A specific asymptotic expansion at large Reynolds numbers (R)for the long
wavelength perturbation of a non stationary anisotropic helical solution of the
force less Navier-Stokes equations (Trkal solutions) is effectively constructed
of the Beltrami type terms through multi scaling analysis. The asymptotic
procedure is proved to be valid for one specific value of the scaling
parameter,namely for the square root of the Reynolds number (R).As a result
large scale structures arise as gradient lines of the energy determined by the
initial conditions for two anisotropic Beltrami flows of the same helicity.The
same intitial conditions determine the boundaries of the vortex-velocity tubes,
containing both streamlines and vortex linesComment: 27 pages, 2 figure
T-Cap Pull-Off and Bending Behavior for Stitched Structure
The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is a structural concept that was developed by The Boeing Company to address the complex structural design aspects associated with a pressurized hybrid wing body aircraft configuration. An important design feature required for assembly is the integrally stitched T-cap, which provides connectivity of the corner (orthogonal) joint between adjacent panels. A series of tests were conducted on T-cap test articles, with and without a rod stiffener penetrating the T-cap web, under tension (pull-off) and bending loads. Three designs were tested, including the baseline design used in largescale test articles. The baseline had only the manufacturing stitch row adjacent to the fillet at the base of the T-cap web. Two new designs added stitching rows to the T-cap web at either 0.5- or 1.0-inch spacing along the height of the web. Testing was conducted at NASA Langley Research Center to determine the behavior of the T-cap region resulting from the applied loading. Results show that stitching arrests the initial delamination failures so that the maximum strength capability exceeds the load at which the initial delaminations develop. However, it was seen that the added web stitching had very little effect on the initial delamination failure load, but actually decreased the initial delamination failure load for tension loading of test articles without a stiffener passing through the web. Additionally, the added web stitching only increased the maximum load capability by between 1% and 12.5%. The presence of the stiffener, however, did increase the initial and maximum loads for both tension and bending loading as compared to the stringerless baseline design. Based on the results of the few samples tested, the additional stitching in the T-cap web showed little advantage over the baseline design in terms of structural failure at the T-cap web/skin junction for the current test articles
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