13,726 research outputs found
Binomial Difference Ideal and Toric Difference Variety
In this paper, the concepts of binomial difference ideals and toric
difference varieties are defined and their properties are proved. Two canonical
representations for Laurent binomial difference ideals are given using the
reduced Groebner basis of Z[x]-lattices and regular and coherent difference
ascending chains, respectively. Criteria for a Laurent binomial difference
ideal to be reflexive, prime, well-mixed, perfect, and toric are given in terms
of their support lattices which are Z[x]-lattices. The reflexive, well-mixed,
and perfect closures of a Laurent binomial difference ideal are shown to be
binomial. Four equivalent definitions for toric difference varieties are
presented. Finally, algorithms are given to check whether a given Laurent
binomial difference ideal I is reflexive, prime, well-mixed, perfect, or toric,
and in the negative case, to compute the reflexive, well-mixed, and perfect
closures of I. An algorithm is given to decompose a finitely generated perfect
binomial difference ideal as the intersection of reflexive prime binomial
difference ideals.Comment: 72 page
3-D KINETIC CHARACTERISTICS OF OBESE CHILDREN AND NORMAL WEIGHT CHILDREN DURING NORMAL WALKING
Previous researches on obese children walking gait have been mainly focused on the kinematic characteristics, and little focused on the kinetic characteristics. The aim of this study is to identify and compare the kinetic characteristics of the walking gait of obese children with those of normal weight children
GeV {\gamma}-ray Emission Detected by Fermi-LAT Probably Associated with the Thermal Composite Supernova Remnant Kesteven 41 in a Molecular Environment
Hadron emission from supernova remnant (SNR)-molecular cloud (MC) association
systems has been widely regarded as a probe of the shock-accelerated cosmic-ray
protons. Here, we report on the detection of a {\gamma}-ray emission source,
with a significance of 24{\sigma} in 0.2-300 GeV, projected to lie to the
northwest of the thermal composite SNR Kesteven 41, using 5.6 years of
Fermi-Large Area Telescope (LAT) observation data. No significant long-term
variability in the energy range 0.2--300 GeV is detected around this source.
The 3{\sigma} error circle, 0.09 degree; in radius, covers the 1720MHz OH maser
and is essentially consistent with the location of the V_{LSR} ~-50 km/s MC
with which the SNR interacts. The source emission has an exponential cutoff
power-law spectrum with a photon index of 1.9+/-0.1 and a cutoff energy of
4.0+/-0.9 GeV, and the corresponding 0.2-300 GeV luminosity is ~1.3*10^36 erg/s
at a distance of 12 kpc. There is no radio pulsar in the 3{\sigma} circle
responsible for the high {\gamma}-ray luminosity. While the inverse Compton
scattering scenario would lead to a difficulty in the electron energy budget,
the source emission can naturally be explained by the hadronic interaction
between the relativistic protons accelerated by the shock of SNR Kesteven 41
and the adjacent northwestern MC. In this paper, we present a list of Galactic
thermal composite SNRs detected at GeV {\gamma}-ray energies by Fermi-LAT is
presented
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