Spatio-Temporal Characteristics of Global Warming in the Tibetan Plateau during the Last 50 Years Based on a Generalised Temperature Zone - Elevation Model

Temperature is one of the primary factors influencing the climate and ecosystem, and examining its change and fluctuation could elucidate the formation of novel climate patterns and trends. In this study, we constructed a generalised temperature zone elevation model (GTEM) to assess the trends of climate change and temporal-spatial differences in the Tibetan Plateau (TP) using the annual and monthly mean temperatures from 1961-2010 at 144 meteorological stations in and near the TP. The results showed the following: (1) The TP has undergone robust warming over the study period, and the warming rate was 0.318°C/decade. The warming has accelerated during recent decades, especially in the last 20 years, and the warming has been most significant in the winter months, followed by the spring, autumn and summer seasons. (2) Spatially, the zones that became significantly smaller were the temperature zones of -6°C and -4°C, and these have decreased 499.44 and 454.26 thousand sq km from 1961 to 2010 at average rates of 25.1% and 11.7%, respectively, over every 5-year interval. These quickly shrinking zones were located in the northwestern and central TP. (3) The elevation dependency of climate warming existed in the TP during 1961-2010, but this tendency has gradually been weakening due to more rapid warming at lower elevations than in the middle and upper elevations of the TP during 1991-2010. The higher regions and some low altitude valleys of the TP were the most significantly warming regions under the same categorizing criteria. Experimental evidence shows that the GTEM is an effective method to analyse climate changes in high altitude mountainous regions

Control of composition and structure for molybdenum nitride films synthesized using ion beam assisted deposition

The purpose of the research described in this article was to synthesize molybdenum nitride films with well‐defined structures and stoichiometries using ion beam assisted deposition (IBAD). Approximately 400 nm thick films were prepared by the evaporative deposition of molybdenum while simultaneously bombarding the growing film with low energy (250–1000 eV) nitrogen ions. The effects of ion‐to‐atom arrival rate ratio, ion angle of incidence, and ion energy on the film composition and phase constituents were examined. The film nitrogen to molybdenum stoichiometry increased linearly with increasing arrival rate ratio irrespective of the ion energy and varied significantly with changes in the ion angle of incidence. The latter was interpreted based on sputtering and reflection effects. The phase constituents were functions of all of the deposition parameters investigated. We propose that a single parameter, the effective energy density per deposited atom, can account for the effects of ion energy, mass, and angle of incidence. The effective energy density is approximately the ion energy divided by the ion range. The range incorporates the effects of ion mass and angle of incidence, as well as the energy. For low energy ions the energy density per depositing atom is proportional to E1/2, a dependence that it shares with other models that have been developed to account for phase formation during IBAD. The advantage of the energy density treatment is that it has a more obvious influence on the temperature in the growth zone, a factor controlling phase formation. © 1995 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69720/2/JAPIAU-77-10-5138-1.pd

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum