23,766 research outputs found
A theory of hyperfinite sets
We develop an axiomatic set theory -- the Theory of Hyperfinite Sets THS,
which is based on the idea of existence of proper subclasses of big finite
sets. We demonstrate how theorems of classical continuous mathematics can be
transfered to THS, prove consistency of THS and present some applications.Comment: 28 page
Collisional damping of surface waves in the solar corona
The damping of surface waves by viscosity and heat conduction is evaluated. For the solar corona, it is found that surface waves dissipate efficiently only if their periods are shorter than a few tens of seconds and only if the background magnetic field is less than about 10 Gauss. Heating of quiet coronal regions is possible if the coronal waves have short periods, but they cannot heat regions of strong magnetic field, such as coronal active region loops
Mollusca of the Illinois River, Arkansas
The Illinois River is in the Ozark region of northwestern Arkansas and eastern Oklahoma. A survey of the Illinois River in Arkansas produced nine species and one morphological subspecies of gastropods, three species of sphaeriid clams, and 23 species of unionid mussels. Museum records resulted in another two species and an ecophenotype of the Unionidae. This represents the first published survey of molluscan species from the Illinois River in Arkansas
The Gordon-Haus effect for modified NLS solitons
Random jitter in the soliton arrival time (the Gordon-Haus effect) is
analyzed for solitons being solutions of the integrable modified nonlinear
Schroedinger equation. It is shown that the mean square fluctuation of the
soliton position depends on the soliton parameters which can be properly
adjusted to suppress the Gordon-Haus jitter.Comment: LaTeX, 7 pages, 3 figures, to be published in Europhys. Let
Early diffusion evidence of retrograde transsynaptic degeneration in the human visual system
We investigated whether diffusion tensor imaging (DTI) indices of white matter integrity would offer early markers of retrograde transsynaptic degeneration (RTD) in the visual system after stroke
Objective: We investigated whether diffusion tensor imaging (DTI) indices of white matter integrity
would offer early markers of retrograde transsynaptic degeneration (RTD) in the visual system
after stroke.
Methods: We performed a prospective longitudinal analysis of the sensitivity of DTI markers of
optic tract health in 12 patients with postsynaptic visual pathway stroke, 12 stroke controls,
and 28 healthy controls. We examined group differences in (1) optic tract fractional anisotropy
(FA-asymmetry), (2) perimetric measures of visual impairment, and (3) the relationship between
FA-asymmetry and perimetric assessment.
Results: FA-asymmetry was higher in patients with visual pathway lesions than in control groups.
These differences were evident 3 months from the time of injury and did not change significantly
at 12 months. Perimetric measures showed evidence of impairment in participants with visual
pathway stroke but not in control groups. A significant association was observed between
FA-asymmetry and perimetric measures at 3 months, which persisted at 12 months.
Conclusions: DTI markers of RTD are apparent 3 months from the time of injury. This represents
the earliest noninvasive evidence of RTD in any species. Furthermore, these measures associate
with measures of visual impairment. DTI measures offer a reproducible, noninvasive, and sensitive
method of investigating RTD and its role in visual impairment
Dietary modifications for infantile colic
Infantile colic can be defined as periods of inconsolable, unexplained, and incessant crying in a seemingly healthy infant that, quite understandably, leads to exhausted, frustrated, and concerned parents seeking to comfort their child (Landgren 2010).
The prevalence of excessive crying varies according to the definition used although, most often, it peaks during the second month of life,with a prevalence of 1.5%to 11.9%(Reijneveld 2001).Traditionally, the definition of the condition was based on the rule of
three (Wessel 1954): that is, unexplained episodes of paroxysmal crying for more than three hours per day, for three days per week, for at least three weeks. More recently a new definition has been proposed. It refers to a clinical condition of fussing and crying for at least one week in an otherwise healthy infant (Hyman 2006). Colic can be graded as mild, moderate, or severe, though there is no consensus for this classification. Colic can affect up to 10% to 30% of infants worldwide (Clifford 2002; Rosen 2007)
On charged impurity structures in liquid helium
The thermoluminescence spectra of impurity-helium condensates (IHC) submerged in superfluid helium have
been observed for the first time. Thermoluminescence of impurity-helium condensates submerged in superfluid
helium is explained by neutralization reactions occurring in impurity nanoclusters. Optical spectra of excited
products of neutralization reactions between nitrogen cations and thermoactivated electrons were rather different
from the spectra observed at higher temperatures, when the luminescence due to nitrogen atom recombination
dominates. New results on current detection during the IHC destruction are presented. Two different mechanisms
of nanocluster charging are proposed to describe the phenomena observed during preparation and warmup
of IHC samples in bulk superfluid helium, and destruction of IHC samples out of liquid helium
Periodic and Quasi-Periodic Compensation Strategies of Extreme Outages caused by Polarization Mode Dispersion and Amplifier Noise
Effect of birefringent disorder on the Bit Error Rate (BER) in an optical
fiber telecommunication system subject to amplifier noise may lead to extreme
outages, related to anomalously large values of BER. We analyze the Probability
Distribution Function (PDF) of BER for various strategies of Polarization Mode
Dispersion (PMD) compensation. A compensation method is proposed that is
capable of more efficient extreme outages suppression, which leads to
substantial improvement of the fiber system performance.Comment: 3 pages, 1 figure, Submitted to IEEE Photonics Letter
Corporate venture capitalists and independent venture capitalists: what do they know, who do they know, and should entrepreneurs care?
While a strong stream of research has examined the value-added by venture capitalists and some recent research has also explored the value added by corporate venture capitalists, the value-added provided by these two types of investors for their portfolio companies has not been compared systematically. This study proposes to make such an evaluation by comparing the social capital based and knowledge-based forms of value added provided by independent and corporate venture capitalists to their portfolio firms. Employing primary data collected from U.S. technology-based new firms that had recently received both corporate venture capital and independent venture capital funding, the present study demonstrates that the value-adding contributions of corporate venture capital and independent venture capital investors are different but complementary.Arthur M. Blank Center kr Entrepreneurship
Babson College, Babson Park, Manachueetts 02457-0310
Kauffinan Center for Entrepreneurial Leadership
Kansas City. Missouri 64112-2776
Co-spcesoerd by
Hunter Centre for Entrepreneurship @ Strathclyde
University of Strathclyde. Glasgow. Scotland
Scottish Enterprise, Glasgow; Scotland
The Entrepreneurial Exchange, Hamilton, Scotland
Linc Scotland, Glasgow, Scotland
Glasgow City Council. Glasgow Scotlan
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