19,716 research outputs found
Transitive and Co-Transitive Caps
A cap in PG(r,q) is a set of points, no three of which are collinear. A cap
is said to be transitive if its automorphism group in PGammaL(r+1,q) acts
transtively on the cap, and co-transitive if the automorphism group acts
transtively on the cap's complement in PG(r,q). Transitive, co-transitive caps
are characterized as being one of: an elliptic quadric in PG(3,q); a
Suzuki-Tits ovoid in PG(3,q); a hyperoval in PG(2,4); a cap of size 11 in
PG(4,3); the complement of a hyperplane in PG(r,2); or a union of Singer orbits
in PG(r,q) whose automorphism group comes from a subgroup of GammaL(1,q^{r+1}).Comment: To appear in The Bulletin of the Belgian Mathematical Society - Simon
Stevi
Social cost considerations and legal constraints in implementing modular integrated utility systems
Social costs associated with the design, demonstration, and implementation of the Modular Integrated Utility System are considered including the social climate of communities, leadership patterns, conflicts and cleavages, specific developmental values, MIUS utility goal assessment, and the suitability of certian alternative options for use in a program of implementation. General considerations are discussed in the field of socio-technological planning. These include guidelines for understanding the conflict and diversity; some relevant goal choices and ideas useful to planners of the MIUS facility
Nonflammable, antistatic, and heat-sealable film
Antistatic, heat-sealable, nonflammable films prepared from polyvinylidene fluoride and polyvinylidene chloride resin
Modulation of endoglin expression in islets of langerhans by VEGF reveals a novel regulator of islet endothelial cell function
BACKGROUND: Endoglin/CD105 is an auxiliary receptor for transforming growth factor-β with established roles in vascular remodelling. It has recently been shown that heterozygous endoglin deficiency in mice decreases insulin secretion in an animal model of obesity, highlighting a potential role for endoglin in the regulation of islet function. We have previously identified two different populations of endoglin expressing cells in human and mouse islets which are: (i) endothelial cells (ECs) and (ii) islet mesenchymal stromal cells. The contribution of islet EC endoglin expression to islet development and sensitivity to VEGF is unknown and is the focus of this study. RESULTS: In vitro culture of mouse islets with VEGF164 for 48 h increased endoglin mRNA levels above untreated controls but VEGF did not modulate VEGFR2, CD31 or CD34 mRNA expression or islet viability. Removal of EC-endoglin expression in vivo reduced islet EC area but had no apparent effect on islet size or architecture. CONCLUSION: EC-specific endoglin expression in islets is sensitive to VEGF and plays partial roles in driving islet vascular development, however such regulation appears to be distinct to mechanisms required to modulate islet viability and size
Liquid mercury cathode electron bombardment ion thrusters Summary report, 1 Aug. 1964 - 31 Oct. 1966
Life tests of liquid mercury cathodes for electron bombardment ion thruster
Community-linked maternal death review (CLMDR) to measure and prevent maternal mortality: a pilot study in rural Malawi.
In Malawi, maternal mortality remains high. Existing maternal death reviews fail to adequately review most deaths, or capture those that occur outside the health system. We assessed the value of community involvement to improve capture and response to community maternal deaths
Transients Among Binaries with Evolved Low-Mass Companions
We show that stable disk accretion should be very rare among low-mass X-ray
binaries and cataclysmic variables whose evolution is driven by the nuclear
expansion of the secondary star on the first giant branch. Stable accretion is
confined to neutron-star systems where the secondary is still relatively
massive, and some supersoft white dwarf accretors. All other systems, including
all black-hole systems, appear as soft X-ray transients or dwarf novae. All
long-period neutron-star systems become transient well before most of the
envelope mass is transferred, and remain transient until envelope exhaustion.
This complicates attempts to compare the numbers of millisecond pulsars in the
Galactic disk with their LMXB progenitors, and also means that the pulsar spin
rates are fixed in systems which are transient rather than steady, contrary to
common assumption. The long-period persistent sources Sco X-2, LMC X-2, Cyg X-2
and V395 Car must have minimum companion masses > 0.75 Msun if they contain
neutron stars, and still larger masses if they contain black holes. The
companion in the neutron-star transient GRO J1744-2844 must have a mass <0.87
Msun. The existence of any steady sources at all at long periods supports the
ideas that (a) the accretion disks in many, if not all, LMXBs are strongly
irradiated by the central source, and (b) mass transfer is thermally unstable
in long-period supersoft X-ray sources.Comment: 10 pages, Latex, 1 ps figure, Ap.J., accepted Feb. 15, 199
Stabilized high-power laser system for the gravitational wave detector advanced LIGO
An ultra-stable, high-power cw Nd:YAG laser system, developed for the ground-based gravitational wave detector Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory), was comprehensively characterized. Laser power, frequency, beam pointing and beam quality were simultaneously stabilized using different active and passive schemes. The output beam, the performance of the stabilization, and the cross-coupling between different stabilization feedback control loops were characterized and found to fulfill most design requirements. The employed stabilization schemes and the achieved performance are of relevance to many high-precision optical experiments
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