Conductance fluctuations in the presence of spin scattering

Electron transport through disordered systems that include spin scatterers is studied numerically. We consider three kinds of magnetic impurities: the Ising, the XY and the Heisenberg. By extending the transfer matrix method to include the spin degree of freedom, the two terminal conductance is calculated. The variance of conductance is halved as the number of spin components of the magnetic impurities increases. Application of the Zeeman field in the lead causes a further halving of the variance under certain conditions.Comment: to be published in Phys. Rev.

Intramolecular C–H and C–F Bond Oxygenation by Site-Differentiated Tetranuclear Manganese Models of the OEC

The dangler manganese center in the oxygen-evolving complex (OEC) of photosystem II plays an important role in the oxidation of water to dioxygen. Inspired by the structure of the OEC, we synthesized a series of site-differentiated tetra-manganese clusters [LMn_3(PhPz)_3OMn][OTf]_x (2: x= 2; 3: x = 1) that features an apical manganese ion—distinct from the others—that is appended to a trinuclear manganese core through an μ4-oxygen atom bridge. This cluster design was targeted to facilitate studies of high-valent Mn-oxo formation, which is a proposed step in the mechanism for water oxidation by the OEC. Terminal Mn-oxo species—supported by a multinuclear motif—were targeted by treating 2 and 3 with iodosobenzene. Akin to our previously reported iron complexes, intramolecular arene hydroxylation was observed to yield the C–H bond oxygenated complexes [LMn3(PhPz)_2(OArPz)OMn][OTf]x (5: x = 2; 6: x = 1). The fluorinated series [LMn_3(F_2ArPz)_3OMn][OTf]_x (8: x = 2; 9: x = 1) was also synthesized to mitigate the observed intramolecular hydroxylation. Treatment of 8 and 9 with iodosobenzene results in intramolecular arene C–F bond oxygenation as judged by electrospray ionization mass spectrometry. The observed aromatic C–H and C–F hydroxylation is suggestive of a putative high-valent terminal metal-oxo species, and it is one of the very few examples capable of oxygenating C–F bonds

A 10-Year Experience in Intraoperative Parathyroid Hormone Measurements for Primary Hyperparathyroidism: A Prospective Study of 91 Previous Unexplored Patients

Introduction. Primary hyperparathyroidism (PHP) is characteristically determined by high levels of calcium and high or inappropriate levels of parathyroid hormone (PTH). Technological advances have dramatically changed the surgical technique over the years once intraoperative parathyroid hormone (IOPTH) assay had allowed for focused approaches. Objective. To evaluate our 10-year experience in employing a rapid intraoperative PTH assay for PHP. Methods. A prospective cohort of 91 PHP-operated patients in a tertiary institution in São Paulo, Brazil, from June 2000 to April 2011. Results. We had 85 (93.4%) successful parathyroidectomies, 6 (6.6%) failed parathyroidectomies in 91 previous unexplored patients, and 5 (100%) successful remedial surgeries. The IOPTH was true-positive in 88.5%, true-negative in 7.3%, false-positive in 2.1%, and false-negative in 2.1% of the procedures. IOPTH was able to obviate additional exploration or to ask for additional exploration in 92 (95.8%) procedures. Conclusion. The IOPTH revealed to be an important technological adjunct in the current parathyroid surgery for PHP

Effectiveness of method improvements to reduce variability of brood termination rate in honey bee brood studies under semi-field conditions

Quantitative assessments of adverse effects of plant protection products on honey bee brood (Apis mellifera L.) may be carried out according to the methods given by the OECD Guidance Document No. 75 (2007). In recent years a number of studies displayed a strong variability in brood termination rates, a key endpoint. Due to these variances no definite conclusions regarding potential brood effects were possible, and the studies needed to be repeated. Due to this, attempts to improve the methodology were initiated by the Working Group ‘Honey bee brood' of the German AG Bienenschutz. In 2011, honey bee brood studies adapted to these identified possible improvements resulted in better results compared to historical data. Based on the analysed results, the working group recommends to improve the method by using bigger colonies with more brood, using 4 instead of 3 replicates for better interpretation of data, starting the study early in the season, avoiding major modifications of the colonies shortly before application and using larger tunnels with effective crop areas preferably > 80 m². To carry out quicker brood cell assessments to reduce stress for the colonies, it is recommended to use digital brood assessment, which allows marking a higher number of cells (e.g. 200 to 400 cells)

Total Parathyroidectomy with Presternal Intramuscular Autotransplantation in Renal Patients: A Prospective Study of 66 Patients

Surgical treatment of secondary (SHPT) and tertiary hyperparathyroidism (THPT) may involve various surgical approaches. The aim of this paper was to evaluate presternal intramuscular autotransplantation of parathyroid tissue as a surgical option in SHPT and THPT treatment. 66 patients with renal chronic disease underwent surgery from April 2000 to April 2005 at Universidade Federal São Paulo, Brazil. There were 38 SHPT patients (24 women/14 men), mean age of 39.yrs (range: 14–58), and 28 THPT patients (14 women/14 men), mean age of 43.4 yrs (range: 24–62). Postoperative average followup was 42.9 months (range: 12–96). Postoperative intact PTH increased throughout followup from 73.5 pg/mL to 133 pg/mL on average from 1st to the 5th year, respectively, in SHPT and from 54.9 pg/mL to 94.7 pg/mL on average from 1st to 5th year, respectively, in THPT group. Definitive hypoparathyroidism was observed in 4 (6.06%) patients and graft-dependent recurrence in 6 (9.09%). Presternal intramuscular autotransplantation of parathyroid tissue is a feasible and safe surgical option in SHPT and THPT treatment

Parathyroid hormone values obtained with immunometric assays depend on the amino-terminal antibody specificity

Introduction of 2nd generation immunometric assays for the measurement of serum parathyroid hormone (PTH), turned them more available, simple and rapid. These methods, based on double identification of the PTH molecule, supposedly measure the intact, bioactive molecule, with the sequence 1-84. Recent works showed that they also measure forms with amino-terminal deletions, like the 7-84 form, which are not able to activate the traditional PTH receptor (PTH1R). Thus, an important practical aspect is the definition of the PTH forms measured by the immunometric assays, a fact that depends on the specificity of the antibodies employed. In this report we compare the results obtained with an in-house immunofluorometric assay that presents a cross-reactivity of 50% with the 7-84 PTH sequence, and two commercial 2nd generation assays, that react 100%. In a first study, 135 samples were measured using our assay and an electrochemiluminescent assay, resulting in a correlation coefficient of 0.961 (P<0.0001) and medians of 35.0 and 51.0ng/L (P<0.0001). In a second study, 252 samples were analyzed using our assay and an immunochemiluminometric assay, resulting in a correlation of 0.883 (P<0.0001) and medians of 36.0 and 45.5ng/L (P<0.0001). In both studies results obtained with the in-house assay were significantly lower, as expected by the specificity of the anti-amino-terminal antibody employed. Our data support the need of a precise description of the specificity of the amino-terminal antibodies employed in 2nd generation PTH assays in order to better compare results and define normal ranges.A introdução de ensaios imunométricos (EIM) de 2ª geração, tornaram a medida de paratormônio (PTH) sérico mais disponível, simples e rápida, aumentando sua utilização. Esses métodos, baseados em dupla identificação da molécula de PTH, mediriam supostamente a molécula intacta, bioativa, de seqüência 1-84. Recentes trabalhos mostraram que eles também medem formas com deleções amino-terminais, como a forma 7-84, que não ativam o receptor tradicional de PTH (PTH1R). Em função disto, um aspecto prático importante é a definição das formas de PTH medidas pelos EIM, sendo que estas dependem da especificidade dos anticorpos empregados. Neste trabalho, comparamos um ensaio imunofluorométrico por nós desenvolvido, que apresenta reatividade cruzada de 50% com a seqüência 7-84 do PTH, com dois ensaios comerciais de 2ª geração, que reagem 100%. Numa 1ª. comparação, 135 amostras de soro foram dosadas com o nosso ensaio e com um ensaio eletroquimioluminescente, obtendo-se uma correlação de 0,961 (P<0,0001) e medianas de 35,0 e 51,0ng/L (P<0,001). Numa 2ª. comparação, 252 amostras foram dosadas com nosso ensaio e com um ensaio imunoquimioluminométrico, obtendo-se uma correlação de 0,883 (P<0,0001) e medianas de 36,0 e 45,5ng/L (P<0,0001). Em ambos os casos, os dados obtidos com nosso ensaio foram significativamente mais baixos, dados condizentes com a especificidade do anticorpo amino-terminal empregado. Nossos dados reiteram a necessidade de descrição precisa da especificidade dos anticorpos amino-terminais empregados em ensaios de PTH de 2ª geração, de maneira a melhor comparar resultados e definir faixas de normalidade.Instituto FleuryUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUNIFESP, EPMSciEL

Effective magnetization damping for a dynamical spin texture in metallic ferromagnet

An additional magnetization damping for an inhomogeneous spin texture in metallic ferromagnets is calculated on the basis of the s–d exchange model. The effect of conduction electrons on the magnetization dynamics is accounted for the case of slowly varying spin texture within adiabatic approximation by using a coordinate transformation to the local quantization axis. The moving magnetic vortex in a circular nanodot made of permalloy is considered as an example. The dependence of the damping on the dot geometrical sizes is obtained. It is found that the additional damping can reach up to 50% of magnitude of the phenomenological Gilbert damping in the Landau–Lifshitz equation of magnetization motion and should be taken into account for any inhomogeneous spin texture dynamics in ferromagnetic metals