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Search Results: 1 - 10 of 3019 matches for " Dennis Orgill "
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A set of genes previously implicated in the hypoxia response might be an important modulator in the rat ear tissue response to mechanical stretch
Vishal Saxena, Dennis Orgill, Isaac Kohane
BMC Genomics , 2007, DOI: 10.1186/1471-2164-8-430
Abstract: With the use of AE, the hypoxia gene set was the most important at a highly significant level. A co-expression network analysis showed that important co-regulated members of the hypoxia pathway include a glucose transporter (slc2a8), heme oxygenase, and nitric oxide synthase2 among others.It appears that the hypoxia pathway may be an important modulator of response of soft tissue to forces. This finding gives us insights not only into the underlying biology, but also into clinical interventions that could be designed to mimic within wounded tissue the effects of forces without all the negative effects that forces themselves create.Worldwide, wounds pose a major health issue. Lower extremity ulcers alone cost the US Medicare system $1.5 billion. Unless wound therapies see a large improvement, we will see escalating treatment costs and morbidity as the population ages and as the incidence of diabetes and obesity increases. An understanding of the mechanisms underlying wound healing will shed light on how normal physiology adapts to changes in the normal homeostatic environment. The vacuum assisted closure (VAC) device (KCI, San Antonio Texas) is a relatively new modality in wound healing. Although the device has been shown to accelerate wound healing, its mode of action remains to be proven convincingly. Figure 1 shows the application of the device. This involves packing a polyurethane sponge into the wound bed and then sealing the wound including the sponge with an occlusive dressing that has one outlet tube going to a vacuum (a vacuum of about 115 mmHg is applied through the tube). Theories about how this device obtains its efficacy range from a reduction in bacterial load [1] to a reduction in edema. The blowup in Figure 1 shows that with the application of the vacuum the skin is pulled into the intra-strut spacings of the sponge thereby stretching the skin.In an earlier publication, we have used a numerical model to show how the imposition of the vacuum forces the
Contact Geometry of Hyperbolic Equations of Generic Type
Dennis The
Symmetry, Integrability and Geometry : Methods and Applications , 2008,
Abstract: We study the contact geometry of scalar second order hyperbolic equations in the plane of generic type. Following a derivation of parametrized contact-invariants to distinguish Monge-Ampère (class 6-6), Goursat (class 6-7) and generic (class 7-7) hyperbolic equations, we use Cartan's equivalence method to study the generic case. An intriguing feature of this class of equations is that every generic hyperbolic equation admits at most a nine-dimensional contact symmetry algebra. The nine-dimensional bound is sharp: normal forms for the contact-equivalence classes of these maximally symmetric generic hyperbolic equations are derived and explicit symmetry algebras are presented. Moreover, these maximally symmetric equations are Darboux integrable. An enumeration of several submaximally symmetric (eight and seven-dimensional) generic hyperbolic structures is also given.
Invariant Yang-Mills connections over Non-Reductive Pseudo-Riemannian Homogeneous Spaces
Dennis The
Physics , 2007, DOI: 10.1090/S0002-9947-09-04797-7
Abstract: We study invariant gauge fields over the 4-dimensional non-reductive pseudo-Riemannian homogeneous spaces G/K recently classified by Fels & Renner (2006). Given H compact semi-simple, classification results are obtained for principal H-bundles over G/K admitting: (1) a G-action (by bundle automorphisms) projecting to left multiplication on the base, and (2) at least one G-invariant connection. There are two cases which admit nontrivial examples of such bundles and all G-invariant connections on these bundles are Yang-Mills. The validity of the principle of symmetric criticality (PSC) is investigated in the context of the bundle of connections and is shown to fail for all but one of the Fels-Renner cases. This failure arises from degeneracy of the scalar product on pseudo-tensorial forms restricted to the space of symmetric variations of an invariant connection. In the exceptional case where PSC is valid, there is a unique G-invariant connection which is moreover universal, i.e. it is the solution of the Euler-Lagrange equations associated to any G-invariant Lagrangian on the bundle of connections. This solution is a canonical connection associated with a weaker notion of reductivity which we introduce.
Contact Geometry of Hyperbolic Equations of Generic Type
Dennis The
Mathematics , 2008, DOI: 10.3842/SIGMA.2008.058
Abstract: We study the contact geometry of scalar second order hyperbolic equations in the plane of generic type. Following a derivation of parametrized contact-invariants to distinguish Monge-Ampere (class 6-6), Goursat (class 6-7) and generic (class 7-7) hyperbolic equations, we use Cartan's equivalence method to study the generic case. An intriguing feature of this class of equations is that every generic hyperbolic equation admits at most a nine-dimensional contact symmetry algebra. The nine-dimensional bound is sharp: normal forms for the contact-equivalence classes of these maximally symmetric generic hyperbolic equations are derived and explicit symmetry algebras are presented. Moreover, these maximally symmetric equations are Darboux integrable. An enumeration of several submaximally symmetric (eight and seven-dimensional) generic hyperbolic structures is also given.
Conformal geometry of surfaces in the Lagrangian--Grassmannian and second order PDE
Dennis The
Mathematics , 2010, DOI: 10.1112/plms/pdr023
Abstract: Of all real Lagrangian--Grassmannians $LG(n,2n)$, only $LG(2,4)$ admits a distinguished (Lorentzian) conformal structure and hence is identified with the indefinite M\"obius space $S^{1,2}$. Using Cartan's method of moving frames, we study hyperbolic (timelike) surfaces in $LG(2,4)$ modulo the conformal symplectic group $CSp(4,R)$. This $CSp(4,R)$-invariant classification is also a contact-invariant classification of (in general, highly non-linear) second order scalar hyperbolic PDE in the plane. Via $LG(2,4)$, we give a simple geometric argument for the invariance of the general hyperbolic Monge--Amp\`ere equation and the relative invariants which characterize it. For hyperbolic PDE of non-Monge--Amp\`ere type, we demonstrate the existence of a geometrically associated ``conjugate'' PDE. Finally, we give the first known example of a Dupin cyclide in a Lorentzian space.
General Theory of Economics: CDR Supply Side Scientific Growth Law Unveiled  [PDF]
Dennis Ridley
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.815223
Abstract: The capitalism (C), democracy (D) and rule of law (R)CDR global invariant hypothesis was previously demonstrated for year 2014 cross country per capita real gross domestic product adjusted for purchasing power parity (G). Consistent with the principle of parsimony, the CDR index explained G with only these three variables. This paper re-estimates the model for the last 22 years of available data. The result is model parameters that are a set of global time invariant constants. These constants constitute the global time invariant CDR index defined by the vector inner (dot) product of the global constants and country C, D, R and C·D·R. This establishes the CDR global time invariant hypothesis. Exogenous and endogenous components of capital are decoupled to calculate and explain the values and roles of new ideas versus old capital stock. Based on the unitary entrepreneurship elasticity of G, the theoretical optimal reinvestment in capital stock is validated by empirical gross fixed capital formation. Together, these place economic growth on a scientific basis. Because of the absence of explicit definitions in the extant literature for concepts such as capitalist, capitalism, entrepreneurship and other consequential terminologies, they are clarified in concise nomenclature.
Active Transport of the Ubiquitin Ligase MID1 along the Microtubules Is Regulated by Protein Phosphatase 2A
Beatriz Aranda-Orgillés, Johanna Aigner, Melanie Kunath, Rudi Lurz, Rainer Schneider, Susann Schweiger
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003507
Abstract: Mutations in the MID1 protein have been found in patients with Opitz BBB/G syndrome (OS), which is characterised by multiple malformations of the ventral midline. MID1 is a microtubule-associated protein that stabilizes microtubules and, in association with the regulatory subunit of protein phosphatase 2A (PP2A), α4, provides ubiquitin ligase activity for the ubiquitin-specific modification of PP2A. Using Fluorescence Recovery After Photobleaching (FRAP) technology, we show here that MID1 is actively and bi-directionally transported along the microtubules, and that this movement is directly linked to its MAP kinase and PP2A-mediated phosphorylation status. Intact transport depends on both kinesins and dyneins and is inhibited upon colcemide treatments. MID1 proteins carrying missense mutations in the α4 binding domain still bind the microtubules but cannot be actively transported. Likewise, knock-down of the α4 protein, inhibition of PP2A activity by okadaic acid and fostriecin or the simulation of permanent phosphorylation at Ser96 in MID1 stop the migration of MID1-GFP, while preserving its microtubule-association. In summary, our data uncover an unexpected and novel function for PP2A, its regulatory subunit α4 and PP2A/α4/mTOR signaling in the active transport of the MID1 ubiquitin ligase complex along the cytoskeleton. Furthermore, a failure in the microtubule directed transport of this protein complex would be an attractive mechanism underlying the pathogenesis of OS in patients with B-box1 mutations.
Urban Vulnerabilities in the Kathmandu Valley, Nepal: Visualizations of Human/Hazard Interactions  [PDF]
Keshav Bhattarai, Dennis Conway
Journal of Geographic Information System (JGIS) , 2010, DOI: 10.4236/jgis.2010.22012
Abstract: Excessive unplanned urban growth leads to many vulnerabilities and impacts on urban environments to varying degrees. However, the majority of the extant literature focuses on the problems related to location and socioeconomic conditions, rather than vulnerability processes and related environmental degradation. This paper analyzes the scope of urban vulnerabilities for five rapidly urbanizing and highly-congested cities in the Kathmandu Valley, Nepal. First, the historic context of the Valley’s uncontrolled urbanization sets the scene. Second, the optic is narrowed to focus upon the geographical features of the resultant urbanized Valley landscape that includes spatial arrangements and of houses, population densities, road networks, vehicular densities, garbage problems, and available open spaces. Additionally, seismic vulnerabilities in the urban areas are also considering in this examination. Third, three-dimensional visualizations of selected urban locations are presented to differentiate between vulnerable and relatively safe locations. The intent of this research is to contribute to the methodological understanding of human/hazards interactions in rapidly urbanizing cities of the Third World, which share similar socioeconomic conditions and environmental con-texts.
The Use of Life Narrative and Living Standard Measurement Survey Data in the Study of Poverty in the Caribbean: A Resolution of Conflicting Epistemologies  [PDF]
Dennis A. V. Brown
Sociology Mind (SM) , 2013, DOI: 10.4236/sm.2013.33030
Abstract:

The paper examines the compatibility or usefulness of fit between epistemologically disparate quantitative survey data and qualitative life narrative data gleaned in the study of poverty in the Caribbean. It aims to find out whether or not the different approaches to the understanding of reality on which the two methodologies are based preclude the integration of their findings as a means of furthering understanding of the dynamics of Caribbean poverty. The analysis draws on Country Poverty Studies conducted in the territory of Grenada in the Eastern Caribbean. It is centered on the demographic measure of fertility, a measure of chronic illnesses by socioeconomic status and life narrative interviews conducted around the themes of poverty, family and life experiences with select poor households across the country. Fertility was measured using parity of women aged <15 - 30+. Statistical analyses were done using cross tabulations. The findings indicate that the hermeneutic understanding of the life narratives, and the causal explanatory accounts provided by the positivist quantitative data, allow for understanding of negative health seeking behaviour on the part of the poor, not provided by the quantitative data by themselves. They also provide insight into the synergy between family, reproductive behaviour, labour market status and chronic poverty in the Caribbean region that would not have been possible through the use of the positivist quantitative method by itself.

Social Pressure on Patient Decision Making through Shifting Mental Models: Presenting Evidence to Patients  [PDF]
Dennis J. Mazur
Sociology Mind (SM) , 2015, DOI: 10.4236/sm.2015.52010
Abstract: In humans, the processes of thinking or making decisions are usually based on mental models. Some of these mental models are designed to represent how humans think and decide, while others aim to improve their thinking and decision making. In decision making related to a patient’s health and medical care, high courts aim to protect the patient’s right to be involved in this process, while societal forces attempt to control costs associated with health and medical decision making. This paper examines legal, decision making, and social theories regarding the societal forces that attempt to influence the grounds upon which a patient thinks and decides about his or her health and medical care.
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