94 research outputs found
Extremal Black Holes As Fundamental Strings
We show that polarization dependent string-string scattering provides new
evidence for the identification of the Dabholkar-Harvey (DH) string solution
with the heterotic string itself. First, we construct excited versions of the
DH solution which carry arbitrary left-moving waves yet are annihilated by half
the supersymmetries. These solutions correspond in a natural way to
Bogomolny-bound-saturating excitations of the ground state of the heterotic
string. When the excited string solutions are compactified to four dimensions,
they reduce to Sen's family of extremal black hole solutions of the toroidally
compactified heterotic string. We then study the large impact parameter
scattering of two such string solutions. We develop methods which go beyond the
metric on moduli space approximation and allow us to read off the subleading
polarization dependent scattering amplitudes. We find perfect agreement with
heterotic string tree amplitude predictions for the scattering of corresponding
string states. Taken together, these results clearly identify the string states
responsible for Sen's extremal black hole entropy. We end with a brief
discussion of implications for the black hole information problem.Comment: 38 pages, 1 encapsulated postscript figure, uses harvmac.tex and
epsf.te
A Survey Evaluating Extent of Undergraduate Medical Education Regarding Sex-Based Differences in Pathophysiology
Introduction
A historical gap in research on sex differences in health outcomes has led to a lack of education on sex-based differences in pathophysiology. The primary objective of this research study was to survey pathophysiology professors of medical schools in the United States (US) to understand the current extent to which the impact of sex on disease is included in the pre-clinical curricula of undergraduate medical institutions in the US.
Methods
A survey tool was created via literature review to assess the extent of education on sex-based differences in pathophysiology. This survey was distributed using the Qualtrics electronic platform to the head professor of pathophysiology at each of the 141 Liaison Committee on Medical Education (LCME) accredited medical schools in the United States.
Results
The survey response rate was 14.9%. The most taught topics were epidemiology of most common cancers affecting each sex and risk factors for development of osteoporosis between different sexes. Sex-based differences in zolpidem dosing, smoking cessation, and the physiologic mechanism of narcotic addiction had the least curricular coverage. 28.57% of faculty and 38.10% of faculty agree and somewhat agree, respectively, their institution provides faculty development for teaching about topics relating to sex differences in pathophysiology. Medical students are primarily evaluated on their knowledge of sex pathophysiology in the form of written examination, followed by evaluation by standardized patients, and lastly faculty observed patient interactions.
Discussion
Curricular topics relating to sex-based differences in pathophysiology are taught to varying degrees in medical school preclinical curricula. Improved efforts can be made to increase instruction on specific topics and to support faculty development in teaching about sex-based differences in disease evaluation and management, enhancing the education of the next generation of physicians and facilitating better care for patients
A novel role for thrombopoietin in regulating osteoclast development in humans and mice
Emerging data suggest that megakaryocytes (MKs) play a significant role in skeletal homeostasis. Indeed, osteosclerosis observed in several MK-related disorders may be a result of increased numbers of MKs. In support of this idea, we have previously demonstrated that MKs increase osteoblast (OB) proliferation by a direct cell-cell contact mechanism and that MKs also inhibit osteoclast (OC) formation. As MKs and OCs are derived from the same hematopoietic precursor, in these osteoclastogenesis studies we examined the role of the main MK growth factor, thrombopoietin (TPO) on OC formation and bone resorption. Here we show that TPO directly increases OC formation and differentiation in vitro. Specifically, we demonstrate the TPO receptor (c-mpl or CD110) is expressed on cells of the OC lineage, c-mpl is required for TPO to enhance OC formation in vitro, and TPO activates the mitogen-activated protein kinases, Janus kinase/signal transducer and activator of transcription, and nuclear factor-kappaB signaling pathways, but does not activate the PI3K/AKT pathway. Further, we found TPO enhances OC resorption in CD14+CD110+ human OC progenitors derived from peripheral blood mononuclear cells, and further separating OC progenitors based on CD110 expression enriches for mature OC development. The regulation of OCs by TPO highlights a novel therapeutic target for bone loss diseases and may be important to consider in the numerous hematologic disorders associated with alterations in TPO/c-mpl signaling as well as in patients suffering from bone disorders
The Bekenstein Formula and String Theory (N-brane Theory)
A review of recent progress in string theory concerning the Bekenstein
formula for black hole entropy is given. Topics discussed include p-branes,
D-branes and supersymmetry; the correspondence principle; the D- and M-brane
approach to black hole entropy; the D-brane analogue of Hawking radiation, and
information loss; D-branes as probes of black holes; and the Matrix theory
approach to charged and neutral black holes. Some introductory material is
included.Comment: 53 pages, LaTeX. v3: Typos fixed, minor updates, references added,
brief Note Added on AdS/CF
Reduction without reduction: Adding KK-monopoles to five dimensional stationary axisymmetric solutions
We present a general method to add KK-monopole charge to any asymptotically
flat stationary axisymmetric solution of five dimensional General Relativity.
The technique exploits the underlying SL(3,R) invariance of the system by
identifying a particular element of the symmetry group which changes the
asymptotic boundary condition and adds KK-monopole charge. Furthermore, we
develop a set of technical tools which allow us to apply the SL(3,R)
transformations to solutions produced by the Inverse Scattering method. As an
example of our methods, we construct the exact solution describing a static
black ring carrying KK-monopole charge.Comment: 36 pages, 3 figures, LaTeX, minor typos fixe
Brane Baldness vs. Superselection Sectors
The search for intersecting brane solutions in supergravity is a large and
profitable industry. Recently, attention has focused on finding localized forms
of known `delocalized' solutions. However, in some cases, a localized version
of the delocalized solution simply does not exist. Instead, localized separated
branes necessarily delocalize as the separation is removed. This phenomenon is
related to black hole no-hair theorems, i.e. `baldness.' We continue the
discussion of this effect and describe how it can be understood, in the case of
Dirichlet branes, in terms of the corresponding intersection field theory. When
it occurs, it is associated with the quantum mixing of phases and lack of
superselection sectors in low dimensional field theories. We find surprisingly
wide agreement between the field theory and supergravity both with respect to
which examples delocalize and with respect to the rate at which this occurs.Comment: 26 pages, ReVTeX, 2 figures, reference added, version to appear in
PR
Gauge Theory and the Excision of Repulson Singularities
We study brane configurations that give rise to large-N gauge theories with
eight supersymmetries and no hypermultiplets. These configurations include a
variety of wrapped, fractional, and stretched branes or strings. The
corresponding spacetime geometries which we study have a distinct kind of
singularity known as a repulson. We find that this singularity is removed by a
distinctive mechanism, leaving a smooth geometry with a core having an enhanced
gauge symmetry. The spacetime geometry can be related to large-N Seiberg-Witten
theory.Comment: 31 pages LaTeX, 2 figures (v3: references added
Genital HSV-2 Infection Induces Short-Term NK Cell Memory
NK cells are known as innate immune cells that lack immunological memory. Recently, it has been shown that NK cells remember encounters with chemical haptens that induce contact hypersensitivity and cytomegalovirus infection. Here, we show the existence of NK cell memory following HSV-2 infection. Stimulation with HSV-2 Ags led to higher IFNÎł production in NK cells that were exposed 30 days previously to HSV-2, compared to NK cells from naĂŻve mice. More importantly, this increased production of IFNÎł in NK cells was independent of B- and T- lymphocytes and specific for the HSV-2 Ags. We also showed that previously exposed NK cells in a B- and T-lymphocyte free environment mediate protection against HSV-2 infection and they are necessary for the protection of mice against HSV-2 infection. Collectively, NK cells remember prior HSV-2 encounters independent of B- and T- lymphocytes leading to protection against HSV-2 mediated morbidity and mortality upon re-exposure
Strategies to Integrate Genomic Medicine into Clinical Care: Evidence from the IGNITE Network
The complexity of genomic medicine can be streamlined by implementing some form of clinical decision support (CDS) to guide clinicians in how to use and interpret personalized data; however, it is not yet clear which strategies are best suited for this purpose. In this study, we used implementation science to identify common strategies for applying provider-based CDS interventions across six genomic medicine clinical research projects funded by an NIH consortium. Each projectâs strategies were elicited via a structured survey derived from a typology of implementation strategies, the Expert Recommendations for Implementing Change (ERIC), and follow-up interviews guided by both implementation strategy reporting criteria and a planning framework, RE-AIM, to obtain more detail about implementation strategies and desired outcomes. We found that, on average, the three pharmacogenomics implementation projects used more strategies than the disease-focused projects. Overall, projects had four implementation strategies in common; however, operationalization of each differed in accordance with each studyâs implementation outcomes. These four common strategies may be important for precision medicine program implementation, and pharmacogenomics may require more integration into clinical care. Understanding how and why these strategies were successfully employed could be useful for others implementing genomic or precision medicine programs in different contexts
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