3,993 research outputs found
Geometrical optics limit of stochastic electromagnetic fields
A method is described which elucidates propagation of an electromagnetic field generated by a stochastic, electromagnetic source within the short wavelength limit. The results can be used to determine statistical properties of fields using ray tracing methods
SDF1-A Facilitates Linā/Sca1+ Cell Homing following Murine Experimental Cerebral Ischemia
Background
Hematopoietic stem cells mobilize to the peripheral circulation in response to stroke. However, the mechanism by which the brain initiates this mobilization is uncharacterized.
Methods
Animals underwent a murine intraluminal filament model of focal cerebral ischemia and the SDF1-A pathway was evaluated in a blinded manner via serum and brain SDF1-A level assessment, Linā/Sca1+ cell mobilization quantification, and exogenous cell migration confirmation; all with or without SDF1-A blockade.
Results
Bone marrow demonstrated a significant increase in Linā/Sca1+ cell counts at 24 hrs (272Ā±60%; P<0.05 vs sham). Mobilization of Linā/Sca1+ cells to blood was significantly elevated at 24 hrs (607Ā±159%; P<0.05). Serum SDF1-A levels were significant at 24 hrs (Sham (103Ā±14), 4 hrs (94Ā±20%, pā=āNS) and 24 hrs (130Ā±17; p<0.05)). Brain SDF1-A levels were significantly elevated at both 4 hrs and 24 hrs (113Ā±7 pg/ml and 112Ā±10 pg/ml, respectively; p<0.05 versus sham 76Ā±11 pg/ml). Following administration of an SDF1-A antibody, Linā/Sca1+ cells failed to mobilize to peripheral blood following stroke, despite continued up regulation in bone marrow (stroke bone marrow cell count: 536Ā±65, blood cell count: 127Ā±24; p<0.05 versus placebo). Exogenously administered Linā/Sca1+ cells resulted in a significant reduction in infarct volume: 42Ā±5% (stroke alone), versus 21Ā±15% (Stroke+Linā/Sca1+ cells), and administration of an SDF1-A antibody concomitant to exogenous administration of the Linā/Sca1+ cells prevented this reduction. Following stroke, exogenously administered Linā/Sca1+ FISH positive cells were significantly reduced when administered concomitant to an SDF1-A antibody as compared to without SDF1-A antibody (10Ā±4 vs 0.7Ā±1, p<0.05).
Conclusions
SDF1-A appears to play a critical role in modulating Linā/Sca1+ cell migration to ischemic brain
Minimally Invasive Mitral Valve Surgery III: Training and Robotic-Assisted Approaches.
Minimally invasive mitral valve operations are increasingly common in the United States, but robotic-assisted approaches have not been widely adopted for a variety of reasons. This expert opinion reviews the state of the art and defines best practices, training, and techniques for developing a successful robotics program
Minimally Invasive Mitral Valve Surgery I: Patient Selection, Evaluation, and Planning.
Widespread adoption of minimally invasive mitral valve repair and replacement may be fostered by practice consensus and standardization. This expert opinion, first of a 3-part series, outlines current best practices in patient evaluation and selection for minimally invasive mitral valve procedures, and discusses preoperative planning for cannulation and myocardial protection
Minimally Invasive Mitral Valve Surgery II: Surgical Technique and Postoperative Management.
Techniques for minimally invasive mitral valve repair and replacement continue to evolve. This expert opinion, the second of a 3-part series, outlines current best practices for nonrobotic, minimally invasive mitral valve procedures, and for postoperative care after minimally invasive mitral valve surgery
Cataclysmic Variables from SDSS II. The Second Year
The first full year of operation following the commissioning year of the
Sloan Digital Sky Survey has revealed a wide variety of newly discovered
cataclysmic variables. We show the SDSS spectra of forty-two cataclysmic
variables observed in 2002, of which thirty-five are new classifications, four
are known dwarf novae (CT Hya, RZ Leo, T Leo and BZ UMa), one is a known CV
identified from a previous quasar survey (Aqr1) and two are known ROSAT or
FIRST discovered CVs (RX J09445+0357, FIRST J102347.6+003841). The SDSS
positions, colors and spectra of all forty-two systems are presented. In
addition, the results of follow-up studies of several of these objects identify
the orbital periods, velocity curves and polarization that provide the system
geometry and accretion properties. While most of the SDSS discovered systems
are faint (>18th mag) with low accretion rates (as implied from their spectral
characteristics), there are also a few bright objects which may have escaped
previous surveys due to changes in the mass transfer rate.Comment: Accepted for publication in The Astronomical Journal, Vol. 126, Sep.
2003, 44 pages, 25 figures (now with adjacent captions), AASTeX v5.
Serologic Evidence for Novel Poxvirus in Endangered Red Colobus Monkeys, Western Uganda
Enzyme-linked immunosorbent assay, Western blot, and virus neutralization assays indicated that red colobus monkeys in Kibale National Park, western Uganda, had antibodies to a virus that was similar, but not identical, to known orthopoxviruses. The presence of a novel poxvirus in this endangered primate raises public health and conservation concerns
The economic and innovation contribution of universities: a regional perspective
Universities and other higher education institutions (HEIs) have come to be regarded as key sources of knowledge utilisable in the pursuit of economic growth. Although there have been numerous studies assessing the economic and innovation impact of HEIs, there has been little systematic analysis of differences in the relative contribution of HEIs across regions. This paper provides an exploration of some of these differences in the context of the UKās regions. Significant differences are found in the wealth generated by universities according to regional location and type of institution. Universities in more competitive regions are generally more productive than those located in less competitive regions. Also, traditional universities are generally more productive than their newer counterparts, with university productivity positively related to knowledge commercialisation capabilities. Weaker regions tend to be more dependent on their universities for income and innovation, but often these universities under-perform in comparison to counterpart institutions in more competitive regions. It is argued that uncompetitive regions lack the additional knowledge infrastructure, besides universities, that are more commonly a feature of more competitive regions
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