2,530 research outputs found
Deformation of generic submanifolds in a complex manifold
This paper shows that an arbitrary generic submanifold in a complex manifold
can be deformed into a 1-parameter family of generic submanifolds satisfying
strong nondegeneracy conditions. The proofs use a careful analysis of the jet
spaces of embeddings satisfying certain nondegeneracy properties, and also make
use of the Thom transversality theorem, as well as the stratification of
real-algebraic sets. Optimal results on the order of nondegeneracy are given.Comment: 24 page
Mapping Genes for Fatness and Growth on Pig Chromosome 13: A Search in the Region Close to the Pig PIT1 Gene
Previous research has shown that the PIT1 gene in several pig populations and the chromosomal region near PIT1 in some pig populations has been significantly associated with fatness and growth on pig chromosome 13. To confirm these previous results and to clarify the role of the PIT1 gene in controlling pig fatness and growth, this research project was focused on studying the chromosomal region close to the PIT1 gene. The ISU Chinese x U.S. pig families were used and the traits analyzed were birth weight, 21-day weight, 42-day weight, longissimus muscle area, backfat thickness at several locations, meat color, marbling and firmness on the carcass, and growth rate for selected time periods. The total number of F2 pigs used ranged from 241 to 330. Significant evidence of a genetic marker for first rib backfat thickness was detected approximately 20 centimorgans (cM) from the PIT1 gene. Evidence of a genetic marker for birth weight was detected at the estimated PIT1 position. These results confirmed the previous published research on pig chromosome 13 for the birth weight but suggest that other genes in the region may be partly responsible for the earlier results on the backfat thickness
Validity and equivalence of the SF-12v2 Health Survey for a Chinese Population
Poster Session 3: no. 124/1264Conference Theme: Integrating HRQOL in Health Care Policy, Research, and Practic
The near-synchronous polar V1432 Aql (RX J1940.1-1025): Accretion geometry and synchronization time scale
The magnetic Cataclysmic Variable (mCV) V1432 Aql (RX 1940.1-1025) belongs to
the four-member subclass of near-synchronous polars with a slight
non-synchronism (<2 %) between the spin period of the white dwarf and the
binary period. In these systems the accretion geometry changes periodically
with phase of the beat cycle. We present the application of a dipole accretion
model for near-synchronous systems developed by Geckeler & Staubert (1997a) to
extended optical and X-ray data. We detect a significant secular change of the
white dwarf spin period in V1432 Aql of dP_spin/dt = -5.4 (+3.7/-3.2) 10-9 s/s
from the optical data set alone. This corresponds to a synchronization time
scale tau_sync = 199 (+441/-75) yr, comparable to the time scale of 170 yr for
V1500 Cyg. The synchronization time scale in V1432 Aql is in excellent
agreement with the theoretical prediction from the dominating magnetic torque
in near-synchronous systems. We also present period analyses of optical CCD
photometry and RXTE X-ray data, which argue against the existence of a 4000 s
period and an interpretation of V1432 Aql as an intermediate polar. The dipole
accretion model also allows to constrain the relevant parameters of the
accretion geometry in this system: the optical data allow an estimate of the
dimensionless parameter (R_t0'/R_wd)1/2 sin(beta) = 3.6 (+2.7/-1.1), with a
lower limit for the threading radius of R_t0' > 10 R_wd (68% confidence).Comment: 12 pages, 10 figures, 6 tables accepted by A&
Analytic and Gevrey Hypoellipticity for Perturbed Sums of Squares Operators
We prove a couple of results concerning pseudodifferential perturbations of
differential operators being sums of squares of vector fields and satisfying
H\"ormander's condition. The first is on the minimal Gevrey regularity: if a
sum of squares with analytic coefficients is perturbed with a
pseudodifferential operator of order strictly less than its subelliptic index
it still has the Gevrey minimal regularity. We also prove a statement
concerning real analytic hypoellipticity for the same type of
pseudodifferential perturbations, provided the operator satisfies to some extra
conditions (see Theorem 1.2 below) that ensure the analytic hypoellipticity
Observations of the transient X-ray source 4U0115+63
Results of HEAO-2 pointed observations and Ariel 5 All Sky Monitor observations of the X-ray transient 4U0115+63 are presented. The transient source pulses with a period of 3.6136 s + or - .0004 s, has a hard spectrum typical of an X-ray binary pulsar, and has a broad iron line emission feature. A discussion of the transient behavior is given and inferences are made concerning the nature of the X-ray source based on the pointed data
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