Weak Localization Effect in Superconductors by Radiation Damage

Large reductions of the superconducting transition temperature $T_{c}$ and the accompanying loss of the thermal electrical resistivity (electron-phonon interaction) due to radiation damage have been observed for several A15 compounds, Chevrel phase and Ternary superconductors, and $\rm{NbSe_{2}}$ in the high fluence regime. We examine these behaviors based on the recent theory of weak localization effect in superconductors. We find a good fitting to the experimental data. In particular, weak localization correction to the phonon-mediated interaction is derived from the density correlation function. It is shown that weak localization has a strong influence on both the phonon-mediated interaction and the electron-phonon interaction, which leads to the universal correlation of $T_{c}$ and resistance ratio.Comment: 16 pages plus 3 figures, revtex, 76 references, For more information, Plesse see http://www.fen.bilkent.edu.tr/~yjki

DiGeorge Syndrome: a not so rare disease

INTRODUCTION: The DiGeorge Syndrome was first described in 1968 as a primary immunodeficiency resulting from the abnormal development of the third and fourth pharyngeal pouches during embryonic life. It is characterized by hypocalcemia due to hypoparathyroidism, heart defects, and thymic hypoplasia or aplasia. Its incidence is 1:3000 live births and, despite its high frequency, little is known about its natural history and progression. ←This is probably due to diagnostic difficulties and the great variety of names used to describe it, such as velocardiofacial, Shprintzen, DiGeorge, and CATCH 22 Syndromes, as well as conotruncal facial anomaly. All represent the same genetic condition, chromosome 22q11.2 deletion, which might have several clinical expressions. OBJECTIVES: To describe clinical and laboratorial data and phenotypic characteristics of patients with DiGeorge Syndrome. METHODS: Patients underwent standard clinical and epidemiological protocol and tests to detect heart diseases, facial abnormalities, dimorphisms, neurological or behavioral disorders, recurrent infections and other comorbidities. RESULTS: Of 14 patients (8m - 18y11m), only one did not have 22q11.2 deletion detected. The main findings were: conotruncal malformation (n = 12), facial abnormalities (n = 11), hypocalcemia (n = 5) and low lymphocyte count (n=2). CONCLUSION: The authors pointed out the necessity of DGS suspicion in all patient presenting with heart defects, facial abnormalities (associated or not with hypocalcemia), and immunological disorders because although frequency of DGS is high, few patients with a confirmed diagnosis are followed up

A New Method of Probing the Phonon Mechanism in Superconductors including MgB2_{2}

Weak localization has a strong influence on both the normal and superconducting properties of metals. In particular, since weak localization leads to the decoupling of electrons and phonons, the temperature dependence of resistance (i.e., $\lambda_{tr}$) is decreasing with increasing disorder, as manifested by Mooij's empirical rule. In addition, Testardi's universal correlation of $T_{c}$ (i.e., $\lambda$) and the resistance ratio (i.e., $\lambda_{tr}$) follows. This understanding provides a new means to probe the phonon mechanism in superconductors including MgB$_{2}$. The merits of this method are its applicability to any superconductors and its reliability because the McMillan's electron-phonon coupling constant $\lambda$ and $\lambda_{tr}$ change in a broad range, from finite values to zero, due to weak localization. Karkin et al's preliminary data of irradiated MgB$_{2}$ show the Testardi correlation, indicating that the dominant pairing mechanism in MgB$_{2}$ is the phonon-mediated interaction.Comment: 9 pages, latex, 3 figure

Do Interventions Designed to Support Shared Decision-Making Reduce Health Inequalities? : A Systematic Review and Meta-Analysis

Copyright: © 2014 Durand et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background: Increasing patient engagement in healthcare has become a health policy priority. However, there has been concern that promoting supported shared decision-making could increase health inequalities. Objective: To evaluate the impact of SDM interventions on disadvantaged groups and health inequalities. Design: Systematic review and meta-analysis of randomised controlled trials and observational studies.Peer reviewe

Coocorrência de mutações nos genes PTPN11 e SOS1 na síndrome de Noonan: este achado prediz um fenótipo mais grave?

Noonan syndrome (NS) is an autosomal dominant disorder, with variable phenotypic expression, characterized by short stature, facial dysmorphisms and heart disease. Different genes of the RAS/MAPK signaling pathway are responsible for the syndrome, the most common are: PTPN11, SOS1, RAF1, and KRAS. The objective of this study was to report a patient with Noonan syndrome presenting mutations in two genes of RAS/MAPK pathway in order to establish whether these mutations lead to a more severe expression of the phenotype. We used direct sequencing of the PTPN11, SOS1, RAF1, and KRAS genes. We have identified two described mutations in heterozygosity: p.N308D and p.R552G in the genes PTPN11 and SOS1, respectively. The patient has typical clinical features similar to the ones with NS and mutation in only one gene, even those with the same mutation identified in this patient. A more severe or atypical phenotype was not observed, suggesting that these mutations do not exhibit an additive effect.A síndrome de Noonan (SN) é uma doença gênica autossômica dominante, com expressão clínica variável, caracterizada por baixa estatura, dismorfismos faciais e cardiopatia. Diferentes genes da via de sinalização RAS/MAPK são responsáveis pela síndrome, sendo as mais frequentes: PTPN11, SOS1, RAF1 e KRAS. O objetivo deste estudo foi relatar um paciente com SN que apresenta mutações em dois genes da via RAS/MAPK a fim de estabelecer se essas mutações levam a uma expressão mais grave do fenótipo. Utilizou-se sequenciamento direto dos genes PTPN11, SOS1, RAF1 e KRAS. Foram identificadas duas mutações em heterozigose previamente descritas: p.N308D e p.R552G nos genes PTPN11 e SOS1, respectivamente. A paciente apresenta quadro clínico típico semelhante ao dos pacientes com SN e mutação em um único gene, mesmo naqueles com a mesma mutação identificada na paciente. Não foi observado um fenótipo mais grave ou atípico na paciente, sugerindo que as mutações não apresentam um efeito aditivo

Tegumentary manifestations of Noonan and Noonan-related syndromes

OBJECTIVES: Noonan and Noonan-related syndromes are common autosomal dominant disorders with neuro-cardio-facial-cutaneous and developmental involvement. The objective of this article is to describe the most relevant tegumentary findings in a cohort of 41 patients with Noonan or Noonan-related syndromes and to detail certain aspects of the molecular mechanisms underlying ectodermal involvement. METHODS: A standard questionnaire was administered. A focused physical examination and a systematic review of clinical records was performed on all patients to verify the presence of tegumentary alterations. The molecular analysis of this cohort included sequencing of the following genes in all patients: PTPN1, SOS1, RAF1, KRAS, SHOC2 and BRAF. RESULTS: The most frequent tegumentary alterations were xeroderma (46%), photosensitivity (29%), excessive hair loss (24%), recurrent oral ulcers (22%), curly hair (20%), nevi (17%), markedly increased palmar and plantar creases (12%), follicular hyperkeratosis (12%), palmoplantar hyperkeratosis (10%), café-au-lait spots (10%) and sparse eyebrows (7%). Patients with mutations in PTPN11 had lower frequencies of palmar and plantar creases and palmar/plantar hyperkeratosis compared with the other patients. CONCLUSIONS: We observed that patients with mutations in genes directly involved in cell proliferation kinase cascades (SOS1, BRAF, KRAS and RAF1) had a higher frequency of hyperkeratotic lesions compared with patients with mutations in genes that have a more complex interaction with and modulation of cell proliferation kinase cascades (PTPN11)

A New Interpretation of Flux Quantization

We study the effect of Aharonov-Bohm flux on the superconducting state in metallic cylinders. Although Byers and Yang attributed flux quantization to the flux-dependent minimum of kinetic energies of the Cooper pairs, it is shown that kinetic energies do not produce any discernible oscillations in the free energy of the superconducting state (relative to that of normal state) as a function of the flux. This result is indeed anticipated by the observation of persistent current in normal metal rings at low temperature. Instead, we have found that pairing interaction depends on the flux, leading to flux quantization. When the flux $(\Phi$) is given by $\Phi=n\times hc/2e$ (with integer n), the pairing interaction and the free energy become unchanged (even n) or almost unchanged (odd n), due to degenerate-state pairing resulting from the energy level crossing. As a result, flux quantization and Little-Parks oscillations follow.Comment: Revtex, 10 pages, 6 figures, For more information, send me an e-mail at [email protected]

Conclusive quantum steering with superconducting transition edge sensors

Quantum steering allows two parties to verify shared entanglement even if one measurement device is untrusted. A conclusive demonstration of steering through the violation of a steering inequality is of considerable fundamental interest and opens up applications in quantum communication. To date all experimental tests with single photon states have relied on post-selection, allowing untrusted devices to cheat by hiding unfavourable events in losses. Here we close this "detection loophole" by combining a highly efficient source of entangled photon pairs with superconducting transition edge sensors. We achieve an unprecedented ~62% conditional detection efficiency of entangled photons and violate a steering inequality with the minimal number of measurement settings by 48 standard deviations. Our results provide a clear path to practical applications of steering and to a photonic loophole-free Bell test.Comment: Preprint of 7 pages, 3 figures; the definitive version is published in Nature Communications, see below. Also, see related experimental work by A. J. Bennet et al., arXiv:1111.0739 and B. Wittmann et al., arXiv:1111.076

Three-dimensionally Ordered Macroporous Structure Enabled Nanothermite Membrane of Mn2O3/Al

Mn2O3 has been selected to realize nanothermite membrane for the first time in the literature. Mn2O3/Al nanothermite has been synthesized by magnetron sputtering a layer of Al film onto three-dimensionally ordered macroporous (3DOM) Mn2O3 skeleton. The energy release is significantly enhanced owing to the unusual 3DOM structure, which ensures Al and Mn2O3 to integrate compactly in nanoscale and greatly increase effective contact area. The morphology and DSC curve of the nanothermite membrane have been investigated at various aluminizing times. At the optimized aluminizing time of 30 min, energy release reaches a maximum of 2.09 kJ∙g−1, where the Al layer thickness plays a decisive role in the total energy release. This method possesses advantages of high compatibility with MEMS and can be applied to other nanothermite systems easily, which will make great contribution to little-known nanothermite research

Potential for Prebiotics as Feed Additives to Limit Foodborne Campylobacter Establishment in the Poultry Gastrointestinal Tract

Campylobacter as an inhabitant of the poultry gastrointestinal tract has proven to be difficult to reduce with most feed additives. In-feed antibiotics have been taken out of poultry diets due to the negative reactions of consumers along with concerns regarding the generation of antibiotic resistant bacteria. Consequently, interest in alternative feed supplements to antibiotics has grown. One of these alternatives, prebiotics, has been examined as a potential animal and poultry feed additive. Prebiotics are non-digestible ingredients by host enzymes that enhance growth of indigenous gastrointestinal bacteria that elicit metabolic characteristics considered beneficial to the host and depending on the type of metabolite, antagonistic to establishment of pathogens. There are several carbohydrate polymers that qualify as prebiotics and have been fed to poultry. These include mannan-oligosaccharides and fructooligosaccharides as the most common ones marketed commercially that have been used as feed supplements in poultry. More recently, several other non-digestible oligosaccharides have also been identified as possessing prebiotic properties when implemented as feed supplements. While there is evidence that prebiotics may be effective in poultry and limit establishment of foodborne pathogens such as Salmonella in the gastrointestinal tract, less is known about their impact on Campylobacter. This review will focus on the potential of prebiotics to limit establishment of Campylobacter in the poultry gastrointestinal tract and future research directions