138,410 research outputs found
Comparison between TeV and non-TeV BL Lac Objects
BL Lacertae objects (BL Lacs) is the dominant population of TeV emitting
blazars. In this work, we investigate whether there is any special
observational properties for TeV sources. To do so, we will compare the
observational properties of TeV detected BL Lacs (TeV BLs) and non-TeV detected
BL Lac objects (non-TeV BLs). From the 3rd /LAT catalog (3FGL), we can
get 662 BL Lacs, out of which, 47 are TeV BLs and 615 are non-TeV BLs. Their
multi-wavelength flux densities (, , ,
), photon spectral indexes (,
), and effective spectral indexes (
and ) are compiled from the available literatures. Then the
luminosities (, ,
, ) are calculated. From
comparisons, we found that TeV BLs are different from low-synchrotron-peaked
BLs (LSP) and intermediate-synchrotron-peaked BLs (ISP), but TeV BLs show
similar properties as high-synchrotron-peaked BLs (HSP). Therefore, we
concentrated on comparison between TeV HSP BLs and non-TeV HSP BLs. Analysis
results suggest that TeV HSP BLs and non-TeV HSP BLs show some differences in
their and , while their other
properties are quite similar
Axial Anomaly and the Nucleon Spin
In this letter, we have taken a particular Lagrangian, which was introduced
to resolve U(1) problem, as an effective QCD Lagrangian, and have derived a
formula of the quark content of the nucleon spin. The difference between quark
content of the proton (\Delta\Sigma_p) and that of the neutron (\Delta\Sigma_n)
is evaluated by this formula. Neglecting the higher-order isospin corrections,
this formula can reduce to Efremov's results in the large N_c limit.Comment: (1) A few changes and corrections made following Referee. (2) The
difference between quark content of the proton (\Delta\Sigma_p) and that of
the neutron (\Delta\Sigma_n) is evaluated. Neglecting the higher-order
isospin corrections, this formula can reduce to Efremov's results in the
large N_c limi
Experimental investigation of a double-diffused MOS structure
Self-aligned polysilicon gate technology was applied to double-diffused MOS (DMOS) construction in a manner that retains processing simplicity and effectively eliminates parasitic overlap capacitance because of the self-aligning feature. Depletion mode load devices with the same dimensions as the DMOS transistors were integrated. The ratioless feature results in smaller dimension load devices, allowing for higher density integration with no increase in the processing complexity of standard MOS technology. A number of inverters connected as ring oscillators were used as a vehicle to test the performance and to verify the anticipated benefits. The propagation time-power dissipation product and process related parameters were measured and evaluated. This report includes (1) details of the process; (2) test data and design details for the DMOS transistor, the load device, the inverter, the ring oscillator, and a shift register with a novel tapered geometry for the output stages; and (3) an analytical treatment of the effect of the distributed silicon gate resistance and capacitance on the speed of DMOS transistors
Experimental investigation of a shielded complementary Metal-Oxide Semiconductor (MOS) structure
A shielded integrated complimentary MOS transistor structure is described which is used to prevent field inversion in the region not occupied by the gates and which permits the use of a thinner field oxide, reduces the chip area, and has provision for simplified multilayer connections. The structure is used in the design of a static shift register and results in a 20% reduction in area
Formation time distribution of dark matter haloes: theories versus N-body simulations
This paper uses numerical simulations to test the formation time distribution
of dark matter haloes predicted by the analytic excursion set approaches. The
formation time distribution is closely linked to the conditional mass function
and this test is therefore an indirect probe of this distribution. The
excursion set models tested are the extended Press-Schechter (EPS) model, the
ellipsoidal collapse (EC) model, and the non-spherical collapse boundary (NCB)
model. Three sets of simulations (6 realizations) have been used to investigate
the halo formation time distribution for halo masses ranging from dwarf-galaxy
like haloes (, where is the characteristic non-linear mass
scale) to massive haloes of . None of the models can match the
simulation results at both high and low redshift. In particular, dark matter
haloes formed generally earlier in our simulations than predicted by the EPS
model. This discrepancy might help explain why semi-analytic models of galaxy
formation, based on EPS merger trees, under-predict the number of high redshift
galaxies compared with recent observations.Comment: 7 pages, 5 figures, accepted for publication in MNRA
Pair Interaction Potentials of Colloids by Extrapolation of Confocal Microscopy Measurements of Collective Structure
A method for measuring the pair interaction potential between colloidal
particles by extrapolation measurement of collective structure to infinite
dilution is presented and explored using simulation and experiment. The method
is particularly well suited to systems in which the colloid is fluorescent and
refractive index matched with the solvent. The method involves characterizing
the potential of mean force between colloidal particles in suspension by
measurement of the radial distribution function using 3D direct visualization.
The potentials of mean force are extrapolated to infinite dilution to yield an
estimate of the pair interaction potential, . We use Monte Carlo (MC)
simulation to test and establish our methodology as well as to explore the
effects of polydispersity on the accuracy. We use poly-12-hydroxystearic
acid-stabilized poly(methyl methacrylate) (PHSA-PMMA) particles dispersed in
the solvent dioctyl phthalate (DOP) to test the method and assess its accuracy
for three different repulsive systems for which the range has been manipulated
by addition of electrolyte.Comment: 35 pages, 14 figure
- …
