Electron and field interactions with thin films and surfaces Final report

Electron and field interactions with thin films and surface

High-pressure synthesis of superconducting Nb{1-x}B2 (x = 0-0.48) with the maximum Tc = 9.2 K

Superconductivity with Tc above 9 K was found in metal-deficient NbB2 prepared under 5 GPa, while no clear superconductivity was observed down to 3 K in stoichiometric NbB2. The superconductivity was observed above x = 0.04 in Nb1-xB2. and the lattice parameters also changed abruptly at x = 0.04. As x increased, the transition temperature Tc slightly rose and fell with the maximum value of 9.2 K at x = 0.24 for the samples sintered at 5 GPa and 1200 C. The Tc-value changed in the range from 7 K to 9 K, depending on the sintering pressure. A series of Ta1-xB2 (0 =< x =< 0.24) was also synthesized under high pressure to examine a special effect of high-pressure synthesis.Comment: 24 pages including 2 tables and 7 figures, accepted for publication in Physica

Hole Superconductivity in MgB2Mg B_2: a high TcT_c cuprate without Cu

The theory of hole superconductivity explains high temperature superconductivity in cuprates as driven by pairing of hole carriers in oxygen $p\pi$ orbitals in the highly negatively charged $Cu-O$ planes. The pairing mechanism is hole undressing and is Coulomb-interaction driven. We propose that the planes of $B$ atoms in $Mg B_2$ are akin to the $Cu-O$ planes without $Cu$, and that the recently observed high temperature superconductivity in $Mg B_2$ arises similarly from undressing of hole carriers in the planar boron $p_{x,y}$ orbitals in the negatively charged $B^-$ planes. Doping $Mg B_2$ with electrons and with holes should mirror the behavior of underdoped and overdoped high $T_c$ cuprates respectively. We discuss possible ways to achieve higher transition temperatures in boron compounds based on this theory.Comment: A section on isotope effect has been added, as well as other minor change

p38-MK2 signaling axis regulates RNA metabolism after UV-light-induced DNA damage

UV-light-induced DNA damage affects RNA metabolism but the underlying signalling pathways are largely unexplored. Here, the authors show that UV light triggers p38-MK2-mediated phosphorylation of the NELF complex, promoting its release from chromatin and concurrent transcriptional elongation

Heterogeneity and Disorder: Contributions of Rolf Landauer

Rolf Landauer made important contributions to many branches of science. Within the broad area of transport in disordered media, he wrote seminal papers on electrical conduction in macroscopically inhomogeneous materials, as well as fundamental analyses of electron transport in quantum mechanical systems with disorder on the atomic scale. We review here some of these contributions. We also briefly describe some main events in his personal and scientific life.Comment: 10 pages, 3 figures; presented on the occasion when Rolf Landauer was awarded, posthumously, the inaugural ETOPIM Medal at the ETOPIM 8 Conference, which took place during 7--12 June, 2009 in Rethymnon, Cret

Síndrome de Cushing: una causa infrecuente de hiperglucemia.

El síndrome de Cushing ectópico (SCE) se produce como resultado de la producción de la hormona adrenocorticotropa (ACTH) desde neoplasias extrahipofisarias. El SCE es un problema médico poco frecuente y difícil de diagnosticar. Se presenta el caso de un varón de 55 años, fumador activo, sin antecedentes médicos relevantes, que acude al servicio de urgencias por polidipsia y poliuria. Finalmente, tras diversas pruebas complementarias, se establece el juicio clínico de síndrome de Cushing secundario a un carcinoma de célula pequeña

Neonatal jaundice and its management: knowledge, attitude and practice of community health workers in Nigeria

BACKGROUND: Neonatal jaundice (NNJ) is still a leading cause of preventable brain damage, physical and mental handicap, and early death among infants in many communities. Greater awareness is needed among all health workers. The objective of the study was to assess the knowledge of primary health care workers about the description, causes, effective treatment, and sequelae of NNJ. METHODS: The setting was a local government area i.e. an administrative district within the south-western part of Nigeria. Community health workers in this area were interviewed by means of a self-administered questionnaire which focused on awareness and knowledge of neonatal jaundice and its causes, treatment and complications. RESULTS: Sixty-six community health workers participated in the survey and male-to-female ratio was 1:5. Their work experience averaged 13.5 (SD 12.7) years. Only 51.5% of the respondents gave a correct definition of NNJ. 75.8 % knew how to examine for this condition while 84.9 % knew at least two of its major causes in our environment. Also, only 54.5 % had adequate knowledge of effective treatment namely, phototherapy and exchange blood transfusion. Rather than referring affected babies to hospitals for proper management, 13.4 %, 10.4 % and 3 % of the participants would treat with ineffective drugs, natural phototherapy and herbal remedies respectively. None of the participants knew any effective means of prevention. CONCLUSION: Primary health care workers may have inadequate knowledge and misconceptions on NNJ which must be addressed concertedly before the impact of the condition on child health and well-being can be significantly reduced. We recommend regular training workshops and seminars for this purpose

Recent Progress in the Computational Many-Body Theory of Metal Surfaces

In this article we describe recent progress in the computational many-body theory of metal surfaces, and focus on current techniques beyond the local-density approximation of density-functional theory. We overview various applications to ground and excited states. We discuss the exchange-correlation hole, the surface energy, and the work function of jellium surfaces, as obtained within the random-phase approximation, a time-dependent density-functional approach, and quantum Monte Carlo methods. We also present a survey of recent quasiparticle calculations of unoccupied states at both jellium and real surfaces.Comment: 17 pages, 1 figure, to appear in Comput. Phys. Commu