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 $Fermi$/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 ($F_{\rm R}$, $F_{\rm O}$, $F_{\rm X}$, $F_{\gamma}$), photon spectral indexes ($\alpha_{\rm X}^{\rm ph}$, $\alpha_{\gamma}^{\rm ph}$), and effective spectral indexes ($\alpha_{\rm RO}$ and $\alpha_{\rm OX}$) are compiled from the available literatures. Then the luminosities ($\log\,{\nu}L_{\rm R}$, $\log\,{\nu}L_{\rm O}$, $\log\,{\nu}L_{\rm X}$, $\log\,{\nu}L_{\gamma}$) 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 $\alpha_{\rm RO}$ and $\alpha_{\gamma}^{\rm ph}$, while their other properties are quite similar

High efficiency, low cost thin GaAs solar cells

The feasibility of fabricating space-resistant, high efficiency, light-weight, low-cost GaAs shallow-homojunction solar cells for space application is demonstrated. This program addressed the optimal preparation of ultrathin GaAs single-crystal layers by AsCl3-GaAs-H2 and OMCVD process. Considerable progress has been made in both areas. Detailed studies on the AsCl3 process showed high-quality GaAs thin layers can be routinely grown. Later overgrowth of GaAs by OMCVD has been also observed and thin FaAs films were obtained from this process

Shallow-homojunction GaAs solar cells

Single-crystal GaAs shallow-homojunction solar cells on GaAs or Ge substrates, without Ga sub 1-x Al sub x As window layers, that have conversion efficiencies exceeding 20% at AM1 (17% at AMO). Using a simple theoretical model, good fits were obtained between computer calculations and experimental data for external quantum efficiency and conversion efficiency of cells with different values of n+ layer thickness. The calculations not only yield values for material properties of the GaAs layers composing the cells but will also permit the optimization of cell designs for space and terrestrial applications. Preliminary measurements indicate that the shallow-homojunction cells are resistant to electron irradiation. In the best test so far, bombardment with 1 x 10 to the 16th power/sq cm fluence of 1 MeV electrons reduced the short-circuit current by only about 6%

Modeling two-state cooperativity in protein folding

A protein model with the pairwise interaction energies varying as local environment changes, i.e., including some kinds of collective effect between the contacts, is proposed. Lattice Monte Carlo simulations on the thermodynamical characteristics and free energy profile show a well-defined two-state behavior and cooperativity of folding for such a model. As a comparison, related simulations for the usual G\={o} model, where the interaction energies are independent of the local conformations, are also made. Our results indicate that the evolution of interactions during the folding process plays an important role in the two-state cooperativity in protein folding.Comment: 5 figure