1,533 research outputs found
szomorujatek 5 felvonásban - Ărta Shakespeare - fordĂtotta Szász Károly
Debreczeni Városi SzĂnház. Kedden, 1901. Ă©vi november hĂł 26-án.Debreceni Egyetem Egyetemi Ă©s Nemzeti Könyvtá
Observation of out-of-phase bilayer plasmons in YBa_2Cu_3O_7-delta
The temperature dependence of the c-axis optical conductivity \sigma(\omega)
of optimally and overdoped YBa_2Cu_3O_x (x=6.93 and 7) is reported in the far-
(FIR) and mid-infrared (MIR) range. Below T_c we observe a transfer of spectral
weight from the FIR not only to the condensate at \omega = 0, but also to a new
peak in the MIR. This peak is naturally explained as a transverse out-of-phase
bilayer plasmon by a model for \sigma(\omega) which takes the layered crystal
structure into account. With decreasing doping the plasmon shifts to lower
frequencies and can be identified with the surprising and so far not understood
FIR feature reported in underdoped bilayer cuprates.Comment: 7 pages, 3 eps figures, Revtex, epsfi
Eosinophilia in patients infected with the human immunodeficiency virus
The prevalence and significance of peripheral blood eosinophilia in patients infected with the human immunodeficiency virus (HIV) were evaluated. Fifteen of 119 consecutive patients had absolute eosinophil counts of > 450/mm3. During a mean follow-up period of 419 days eosinophilia could be identified as secondary to a parasitic infection in only one patient. Correlation with disease stage showed a higher rate of advanced disease in patients with absolute eosinophilia. In a multivariate regression analysis, only low CD4+ cell counts, not the CDC disease stage or the use of antiretroviral therapy or primary prophylaxis, contributed significantly to the prevalence of eosinophilia. It is concluded that expen-sive laboratory investigations in asymptomatic patients with advanced-stage HIV disease are neither necessary nor cost effectiv
Hole depletion and localization due to disorder in insulating PrBa2Cu3O7-d: a Compton scattering study
The (mostly) insulating behaviour of PrBa2Cu3O7-d is still unexplained and
even more interesting since the occasional appearance of superconductivity in
this material. Since YBa2Cu3O7-d is nominally iso-structural and always
superconducting, we have measured the electron momentum density in these
materials. We find that they differ in a striking way, the wavefunction
coherence length in PrBa2Cu3O7-d being strongly suppressed. We conclude that Pr
on Ba-site substitution disorder is responsible for the metal-insulator
transition. Preliminary efforts at growth with a method to prevent disorder
yield 90K superconducting PrBa2Cu3O7-d crystallites.Comment: 4 pages, 3 figures, revised version submitted to PR
Urban transportation: Perspectives on mobility and choice
A study of urban transportation systems are presented characterized by intensive scrutiny of many ideas, philosophies, and academic perspectives. This report is intended to communicate some dimensions of the urban transportation problem to the general public
Greenhouse gas implications of mobilizing agricultural biomass for energy: a reassessment of global potentials in 2050 under different food-system pathways
Global bioenergy potentials have been the subject of extensive research and continued controversy. Due to vast uncertainties regarding future yields, diets and other influencing parameters, estimates of future agricultural biomass potentials vary widely. Most scenarios compatible with ambitious climate targets foresee a large expansion of bioenergy, mainly from energy crops that needs to be kept consistent with projections of agriculture and food production. Using the global biomass balance model BioBaM, we here present an assessment of agricultural bioenergy potentials compatible with the Food and Agriculture Organization's (2018) 'Alternative pathways to 2050' projections. Mobilizing biomass at larger scales may be associated with systemic feedbacks causing greenhouse gas (GHG) emissions, e.g. crop residue removal resulting in loss of soil carbon stocks and increased emissions from fertilization. To assess these effects, we derive 'GHG cost supply-curves', i.e. integrated representations of biomass potentials and their systemic GHG costs. Livestock manure is most favourable in terms of GHG costs, as anaerobic digestion yields reductions of GHG emissions from manure management. Global potentials from intensive livestock systems are about 5 EJ/yr. Crop residues can provide up to 20 EJ/yr at moderate GHG costs. For energy crops, we find that the medium range of literature estimates (~40 to 90 EJ/yr) is only compatible with FAO yield and human diet projections if energy plantations expand into grazing areas (~4–5 million km2) and grazing land is intensified globally. Direct carbon stock changes associated with perennial energy crops are beneficial for climate mitigation, yet there are—sometimes considerable—'opportunity GHG costs' if one accounts the foregone opportunity of afforestation. Our results indicate that the large potentials of energy crops foreseen in many energy scenarios are not freely and unconditionally available. Disregarding systemic effects in agriculture can result in misjudgement of GHG saving potentials and flawed climate mitigation strategies
Unadulterated spectral function of low energy quasiparticles: Bi-2212, nodal direction
Fitting the momentum distribution photoemission spectra to the Voigt profile
appears to be a robust procedure to purify the interaction effects from the
experimental resolution. In application to Bi-2212 high-Tc cuprates, the
procedure reveals the true scattering rate at low binding energies and
temperatures, and, consequently, the true value of the elastic scattering.
Reaching the minimal value ~ 16 meV, the elastic scattering does not reveal a
systematic dependence on doping level, but is rather sensitive to impurity
concentration, and can be explained by the forward scattering on out-of-plane
impurities. The inelastic scattering is found to form well-defined
quasiparticles with the quadratic and cubic energy dependence of the scattering
rate above and below Tc, respectively. The observed energy-temperature
asymmetry of the scattering rate is also discussed.Comment: 4 revtex pages, 4 figure
Gridded soil surface nitrogen surplus on grazing and agricultural land: Impact of land use maps
Excess N application on agricultural land greatly impacts the environment in multiple ways, driven by population growth and improving quality of human diets. Therefore, it is essential to quantify the sources of the emissions of N compounds and their determinants (e.g. biological N fixation (BNF), mineral fertilizer, manure N and N deposition) to develop adequate mitigation measures. Here we aim at comprehensively mapping and quantifying N fluxes on agricultural land to analyze these sources on different scales. As underlying grazing land maps used for such calculations are fairly different in terms of methodology and definition and thus spatial extent and pattern, we investigate how this diversity in grazing land maps affects quantification of N indicators. We compared three different global grazing land maps and analyzed the propagation of differences to discrepancies in N indicators calculated from them. We discovered that (i) area differences propagated to high discrepancies in N surplus mostly in Asia, and to a minor extent also in Europe and Northern Africa. (ii) BNF constitutes an important translator for differences on grazing land to N indicators, while also being a source of further uncertainty, which warrants further scrutiny. (iii) A more inclusive definition of grazing land results in overall less N surplus given the larger areas included but allows to provide a more comprehensive estimate of the influence of human activity on the N cycle. This study is the first to provide an in-depth analysis of the effect of grazing land and agricultural land area differences on various N budget terms and N indicator calculation, highlighting opportunities for further research, and the importance of a comprehensive accounting of N surplus when using an inclusive definition of grazing land
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