2,705 research outputs found

    Time Constants of Heating and Cooling in the Eastern Water Dragon. Physignathus Lesueurii and Some Generalizations About Heating and Cooling in Reptiles

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    In keeping with other reptiles, core temperature of the lizard Physignathus lesueurii responds more rapidly to a step function increase in temperature than to a corresponding decrease. 2. Observations on twelve species (five families) of non-Chelonian reptiles heating and cooling in air and water show that strongly predictable relationships exist between thermal time constants and body size. Chelonia show a different pattern. 3. These observations are compared with the predictions of a simple model which, although not sufficiently complex to simulate physiological changes, provides insight into the relative importance of the physical and biological factors which underlie the observed relationships

    Detection of functional PTEN lipid phosphatase protein and enzyme activity in squamous cell carcinomas of the head andeck, despite loss of heterozygosity at this locus

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    The human tumour suppressor gene PTEN located at 10q23 is mutated in a variety of tumour types particularly metastatic cases and in the germline of some individuals with Cowdens cancer predisposition syndrome. We have assessed the status of PTEN and associated pathways in cell lines derived from 19 squamous cell carcinomas of the head and neck. Loss of heterozygosity is evident at, or close to the PTEN gene in 5 cases, however there were no mutations in the remaining alleles. Furthermore by Western analysis PTEN protein levels are normal in all of these SCC-HN tumours and cell lines. To assess the possibility that PTEN may be inactivated by another mechanism, we characterized lipid phosphatase levels and from a specific PIP3 biochemical assay it is clear that PTEN is functionally active in all 19 human SCCs. Our data strongly suggest the possibility that a tumour suppressor gene associated with development of SCC-HN, other than PTEN, is located in this chromosomal region. This gene does not appear to be MXI-1, which has been implicated in some other human tumour types. PTEN is an important negative regulator of PI3Kinase, of which subunit alpha is frequently amplified in SCC-HN. To examine the possibility that PI3K is upregulated by amplification in this tumour set we assessed the phosphorylation status of Akt, a downstream target of PI3K. In all cases there is no detectable increase in Akt phosphorylation. Therefore there is no detectable defect in the PI3K pathway in SCC-HN suggesting that the reason for 3q26.3 over-representation may be due to genes other than PI3K110α. © 2001 Cancer Research Campaign http://www.bjcancer.co

    Enhanced radiative strength in the quasi-continuum of 117Sn

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    Radiative strength functions of 117Sn has been measured below the neutron separation energy using the (3He,3He'gamma) reactions. An increase in the slope of the strength functions around E_gamma= 4.5 MeV indicates the onset of a resonance-like structure, giving a significant enhancement of the radiative strength function compared to standard models in the energy region 4.5 <= E_gamma <= 8.0 MeV. For the first time, the functional form of this resonance-like structure has been measured in an odd tin nucleus below neutron threshold in the quasi-continuum region.Comment: 4 pages, 3 figure

    An urban sprawl index based on multivariate and Bayesian factor analysis with application at the municipality level in Valencia

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    [EN] Urban sprawl is now a common and threatening phenomenon in Europe, severely affecting environmental and economic sustainability. An analytical characterization and measurement of urban sprawl are required to gain a better understanding of the phenomenon and to propose the possible solutions. Traditional factor analysis techniques, especially Principal Component Analysis and Factor Analysis, have been commonly used. In this paper, we additionally test Independent Component Analysis with the aim to obtain a multidimensional characterization of the sprawl phenomenon. We also use Bayesian Factor Analysis to obtain a single (unidimensional) measuring index of sprawl, which also allows us to obtain the uncertainty of the inferred index, in contrast to traditional approaches. All these techniques have been applied to study the phenomenon of urban sprawl at the municipality level in Valencia, Spain using a wide set of variables related to the characteristics and patterns of urban land use.Gielen, E.; Riutort-Mayol, G.; Palencia Jiménez, JS.; Cantarino-Martí, I. (2017). An urban sprawl index based on multivariate and Bayesian factor analysis with application at the municipality level in Valencia. Environment and Planning B Planning and Design. 1-27. doi:10.1177/2399808317690148S12

    Hummingbirds Budget Energy Flexibly in Response to Changing Resources

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    A key component of individual fitness is the ability to manage energy stores in response to variable resource availability, but because directly measuring energy budgets is difficult, daily energy management is rarely measured. Hummingbirds\u27 energy management is relatively simple to model compared to other endotherms because they have high mass‐specific metabolic rates and store little fat. We determined which aspects of the hummingbird daily energy budget (i.e. thermoregulation, daytime activity costs, night‐time costs) change at the individual level in response to environmental variation. We found that daily energy expenditure varied threefold in two populations of broad‐billed hummingbirds (Cynanthus latirostris). Our model indicated the energy budget was distributed in the following proportions: daytime activity, 59% (range 22%–84%); thermoregulation, 23% (11%–32%); basal metabolism, 7% (3%–16%); and night‐time energy, 17% (6%–37%). Activity costs were higher at the hotter, homogeneous site and during the early‐wet season at both sites. Increased daily energy expenditure was related to decreased nectar availability and not significantly related to temperature or bird mass. With climate change, the indirect energetic costs of shifting resources could have greater impacts on endotherm energy budgets than direct costs such as thermoregulation. Increased foraging and activity costs could decrease the energy available to birds for somatic repair and reproduction, potentially causing differential fitness across seasons and sites

    Photoactivation experiment on 197Au and its implications for the dipole strength in heavy nuclei

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    The 197Au(gamma,n) reaction is used as an activation standard for photodisintegration studies on astrophysically relevant nuclei. At the bremsstrahlung facility of the superconducting electron accelerator ELBE (Electron Linear accelerator of high Brilliance and low Emittance) of Forschungszentrum Dresden-Rossendorf, photoactivation measurements on 197Au have been performed with bremsstrahlung endpoint energies from 8.0 to 15.5 MeV. The measured activation yield is compared with previous experiments as well as with calculations using Hauser-Feshbach statistical models. It is shown that the experimental data are best described by a two-Lorentzian parametrization with taking the axial deformation of 197Au into account. The experimental 197Au(gamma,n) reaction yield measured at ELBE via the photoactivation method is found to be consistent with previous experimental data using photon scattering or neutron detection methods.Comment: 9 page

    Evolution of level density step structures from 56,57-Fe to 96,97-Mo

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    Level densities have been extracted from primary gamma spectra for 56,57-Fe and 96,97-Mo nuclei using (3-He,alpha gamma) and (3-He,3-He') reactions on 57-Fe and 97-Mo targets. The level density curves reveal step structures above the pairing gap due to the breaking of nucleon Cooper pairs. The location of the step structures in energy and their shapes arise from the interplay between single-particle energies and seniority-conserving and seniority-non-conserving interactions.Comment: 9 pages, including 5 figure

    Clinical Public Health Integration in Medical School Curriculum: Transitioning Medical Student Training from Medical Problems to Health Solutions

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    The current chronic disease burden, growing health disparities, and evolution of our healthcare system require that medical students be equipped with basic public health education to effectively manage patients, navigate the healthcare system, and advocate for health(1,2,3,4,5,6). The Institute of Medicine and the AAMC emphasize the need for physicians to be trained in public health(1,8). The inaugural year of the revised curriculum at The George Washington University School of Medicine and Health Sciences (GW SMHS) represented a first step at the institution to integrate clinical public health into medical education. As part of this process, the Clinical Public Health (CLiPH) Working Group, a student formed curriculum advisory board, was created to give real time feedback and assess the Public Health & Health Policy theme curriculum in the first year at GW SMHS. The project objectives were: 1.) To review and evaluate the effectiveness of the public health theme curriculum in the first year of the revised curriculum, including first year medical students’ perceptions and knowledge of the public health theme. 2.) To develop a proposal to maximize opportunities and achieve better integration of the public health theme into the curriculum. The group aims toward clinical public health integration across the four year medical degree curriculum and better collaboration with the GW Milken School of Public Health (SPH) to create an expanded scope of practice within public health for practicing physicians. Over the summer, the working group engaged with multiple stakeholders to forward the clinical public health agenda at GW SMHS. To conduct the curriculum assessment, the students developed a template and the group reviewed over fifty sessions, in the Public Health & Health Policy Theme, Clinical Skills and Reasoning Course (CSR), and intersession activities. Outside research was done to supplement resources to recommend and improve integration of the clinical public health material into the revised preclinical curriculum. Recommended revisions and developments were sent to faculty stakeholders as resources for the revision process of the curriculum. Future work to revise the curriculum should include study of the evolution of students’ knowledge, attitudes, and beliefs surrounding clinical public health and the impact it has on their development as a physician. To better inform the development of the curriculum and how best to engage students with clinical public health, major stakeholders, such as health departments, community stakeholders, public health experts, and most importantly students should continue to be a part of the dialogue

    A simple method for freeze-fracture of monolayer cultures.

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