Woptic: optical conductivity with Wannier functions and adaptive k-mesh refinement

We present an algorithm for the adaptive tetrahedral integration over the Brillouin zone of crystalline materials, and apply it to compute the optical conductivity, dc conductivity, and thermopower. For these quantities, whose contributions are often localized in small portions of the Brillouin zone, adaptive integration is especially relevant. Our implementation, the woptic package, is tied into the wien2wannier framework and allows including a many-body self energy, e.g. from dynamical mean-field theory (DMFT). Wannier functions and dipole matrix elements are computed with the DFT package Wien2k and Wannier90. For illustration, we show DFT results for fcc-Al and DMFT results for the correlated metal SrVO$_3$.Comment: 14 pages, 10 figures. Changes from v1: corrected prefactor of optical conductivity; minor changes for readabilit

Cubic interaction parameters for t2g Wannier orbitals

Many-body calculations for multi-orbital systems at present typically employ Slater or Kanamori interactions which implicitly assume a full rotational invariance of the orbitals, whereas the real crystal has a lower symmetry. In cubic symmetry, the low-energy $t_{2g}$ orbitals have an on-site Kanamori interaction, albeit without the constraint $U = U' + 2J$ implied by spherical symmetry ($U$: intra-orbital interaction, $U'$: inter-orbital interaction, $J$: Hund's exchange). Using maximally localized Wannier functions we show that deviations from the standard, spherically symmetric interactions are indeed significant for $5d$ orbitals ($\sim25$ for BaOsO$_3$ ; $\sim12$ if screening is included), but less important for $3d$ orbitals ($\sim6\%$ for SrVO$_3$; $\sim1\%$ if screened).Comment: 9 pages, 3 figures, 6 tables; as publishe

Laboratory Bounds on Electron Lorentz Violation

Violations of Lorentz boost symmetry in the electron and photon sectors can be constrained by studying several different high-energy phenomenon. Although they may not lead to the strongest bounds numerically, measurements made in terrestrial laboratories produce the most reliable results. Laboratory bounds can be based on observations of synchrotron radiation, as well as the observed absences of vacuum Cerenkov radiation. Using measurements of synchrotron energy losses at LEP and the survival of TeV photons, we place new bounds on the three electron Lorentz violation coefficients c_(TJ), at the 3 x 10^(-13) to 6 x 10^(-15) levels.Comment: 18 page

Produção de gado de corte e acúmulo de matéria seca em sistemas de integração lavoura: pecuária em presença e ausência de trevo branco e nitrogênio.

O trabalho foi conduzido com o objetivo de verificar a influência da adubação nitrogenada em uma pastagem de azevém (Lolium multiflorium L.) e aveia (Avena strigosa Scherb) em presença e ausência de trevo branco (Trifolium repens L.), conferida pelo acúmulo e produção de matéria seca, ganho médio diário, ganho de peso vivo e carga animal no sistema de integração lavoura-pecuária sob sistema de plantio direto. A cultura antecessora da pastagem foi a soja (Glycine Max L.). O delineamento experimental foi em blocos completos ao acaso, com parcelas subdivididas e três repetições. Nas parcelas, foram testadas quatro doses de nitrogênio (0, 100, 200 e 300 kg.ha-1) e nas subparcelas, a combinação de presença e ausência de trevo branco. A elevação das doses crescentes de N aumentaram de forma linear crescente o acúmulo e a produção de matéria seca da pastagem. A carga animal e o ganho de peso vivo por hectare de bovinos aumentaram com o incremento de nitrogênio. Os resultados demonstram o efeito da adubação nitrogenada no acúmulo diário, na produção de matéria seca, carga animal e no ganho de peso vivo

Measurements of heavy ion beam losses from collimation

The collimation efficiency for Pb ion beams in the LHC is predicted to be lower than requirements. Nuclear fragmentation and electromagnetic dissociation in the primary collimators create fragments with a wide range of Z/A ratios, which are not intercepted by the secondary collimators but lost where the dispersion has grown sufficiently large. In this article we present measurements and simulations of loss patterns generated by a prototype LHC collimator in the CERN SPS. Measurements were performed at two different energies and angles of the collimator. We also compare with proton loss maps and find a qualitative difference between Pb ions and protons, with the maximum loss rate observed at different places in the ring. This behavior was predicted by simulations and provides a valuable benchmark of our understanding of ion beam losses caused by collimation.Comment: 12 pages, 20 figure

Vergleich internationaler Konsensus-Empfehlungen zur Erkennung des präsymptomatischen Hochrisikopatienten für den Herzinfarkt in Deutschland

Summary : The recommendations of the International Task Force for the Prevention of Coronary Heart Disease/International Atherosclerosis Society (ITF/IAS), the US-American Adult Treatment Panel III of the National Cholesterol Education Programs (ATP III) and the 3rd Joint European Guidelines (3JE) for the prevention coronary heart disease (CHD) show good agreement in tertiary prevention. All three guidelines recommend that patients with manifest CHD should have a blood pressure below 140/90 mm Hg and LDL-cholesterol below 2.6 mmol/l (100 mg/dl). By contrast, the three recommendations differ with respect to the prevention of cardiovascular events in asymptomatic high risk patients (secondary prevention), notably in the strategy to be used for risk assessment. Both the ITF/IAS guidelines and the 3JE guidelines can be adapted and realized in the various European countries. We therefore compared the prognostic values of the three recommendations by applying them to the data of male participants of the Prospective Cardiovascular Münster (PROCAM) Study. The ITF/IAS recommendations show the highest specificity (94.5%), positive predictive value (32.0%) and diagnostic efficacy (90.5%); the 3JE guidelines have the highest sensitivity (64.6%) but lowest specificity (77.9%), positive predictive value (17.5%) and diagnostic efficacy (77.0%). The application of the 3JE recommendations would target 25% of German men aged 35-65 years as cardiovascular high risk patients, by contrast to 7.5% through application of the ITF/IAS guidelines. In view of the limited resources in the public health systemthe application of the ITF/IAS guidelines in Germany appears more appropriat

Pan-Africanism: a contorted delirium or a pseudonationalist paradigm? Revivalist critique

This essaic-article goes against established conventions that there is anything ethno-cultural (and hence national) about the so-called African tribes. Drawing largely from the culture history of precolonial/prepolitical Africans—that is, the Bantu/Cushitic-Ethiopians (Azanians)—the author has demonstrated vividly that far from being distinct ethno-culture national communities, the so-called tribes of African states are better considered subculture groups, whose regional culture practices erstwhile paid tribute to their nation’s main culture center in Karnak. For example, using the culture symbols and practices of some local groups and linking them to the predynastic and dynastic Pharaonic periods, I argued that there is compelling evidence against qualifying Africa’s tribes as distinct ethno-culture national entities. In genuine culture context, I stressed that the Ritual of Resurrection and its twin culture process of the mummification of deceased indigenous Pharaohs tend to suggest that the object of the Bantu/Cushitic-Ethiopians national culture was life (in its eternal manifestation) and then resurrection later, and that there are recurring (culturally sanctioned) ethical examples among the culture custodians of these subculture groups that generally pay tribute to the overarching culture norm. Furthermore, the fact that the Ritual of Resurrection began in the Delta region and ended at the Sources of the Nile, where the spirit of the deceased indigenous Pharaohs was introduced into the spiritual world of their ancestors, contradicts conventional perceptions that ancient Egypt was a distinct national community isolated from precolonial/prepolitical Africa/Azania