Universal method for separating spin pumping from spin rectification voltage of ferromagnetic resonance

We develop a method for universally resolving the important issue of separating spin pumping from spin rectification signals in bilayer spintronics devices. This method is based on the characteristic distinction of spin pumping and spin rectification, as revealed in their different angular and field symmetries. It applies generally for analyzing charge voltages in bilayers induced by the ferromagnetic resonance (FMR), independent of FMR line shape. Hence, it solves the outstanding problem that device-specific microwave properties restrict the universal quantification of the spin Hall angle in bilayer devices via FMR experiments. Furthermore, it paves the way for directly measuring the nonlinear evolution of spin current generated by spin pumping. The spin Hall angle in a Py/Pt bilayer is thereby directly measured as 0.021±0.015 up to a large precession cone angle of about 20°.

Impact of the HPV-positivity definition on the prognostic value of HPV status in patients with locally advanced squamous cell carcinoma of the head and neck

BACKGROUND AND PURPOSE

This study re-evaluated the prognostic value of HPV status for loco-regional control (LRC), metastases-free survival (MFS), and survival (OS) in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). A modified definition of HPV positivity was used in the current study compared to the authors' previous study.

PATIENTS AND METHODS

In the previous study of the same 170 patients, a tumor was defined as HPV-positive if it showed a positive in situ hybridization result in ≥10% of tumor cells and/or positive p16 immunostaining. In the current analysis, tumors were considered HPV-positive only if they showed positive results for both in situ hybridization and p16 immunostaining. In addition to HPV status, the same 11 potential prognostic factors were investigated for treatment outcomes as in the preceding study.

RESULTS

In the multivariate analysis of the current study, HPV positivity was significantly associated with improved LRC [risk ratio (RR) 9.78; p<0.001], MFS (RR 7.17; p=0.008), and OS (RR 6.61; p<0.001). In the previous study, HPV positivity was associated with LRC (RR 2.34; p=0.014) and OS (RR 2.19; p=0.019), but not with MFS (RR 2.04; p=0.11).

CONCLUSIONS

Applying the new definition of HPV positivity, the impact of HPV status on the prognosis of patients irradiated for locally advanced SCCHN was more prominent than in our previous study and associated with all three investigated endpoints.

Nanoscale imaging of InN segregation and polymorphism in single vertically aligned InGaN/GaN multi quantum well nanorods by tip-enhanced Raman scattering

Vertically aligned GaN nanorod arrays with nonpolar InGaN/GaN multi quantum wells (MQW) were grown by MOVPE on c-plane GaN-on-sapphire templates. The chemical and structural properties of single nanorods are optically investigated with a spatial resolution beyond the diffraction limit using tip-enhanced Raman spectroscopy (TERS). This enables the local mapping of variations in the chemical composition, charge distribution, and strain in the MQW region of the nanorods. Nanoscale fluctuations of the In content in the InGaN layer of a few percent can be identified and visualized with a lateral resolution below 35 nm. We obtain evidence for the presence of indium clustering and the formation of cubic inclusions in the wurtzite matrix near the QW layers. These results are directly confirmed by high-resolution TEM images, revealing the presence of stacking faults and different polymorphs close to the surface near the MQW region. The combination of TERS and HRTEM demonstrates the potential of this nanoscale near-field imaging technique, establishing TERS as a very potent, comprehensive, and nondestructive tool for the characterization and optimization of technologically relevant semiconductor nanostructures.

[Femoral osteonecrosis - Ahlbaeck's disease]

Osteonecrosis of the knee can present as a spontaneous, primary (SPON) or a secondary clinical entity (SON). The natural history of SPON follows a course of several sequential stages which seem to be irreversible in later stages of both entities. Early diagnosis of ON is crucial and the earlier the stage of the lesion at the time of diagnosis, the better the prognosis. Clinically, early diagnosis and treatment of ON might prevent unnecessary surgery in cases with a concomitant degenerative meniscal tear. From a medicolegal viewpoint early-stage ON should be ruled out prior to surgery as arthroscopy has recently been associated with ON. Recent biopsy studies showed that SPONK is most likely caused by insufficiency fractures which seem to appear as osteonecrotic lesions in later stages of the disease due to failed bone healing.

Probing local strain and composition in Ge nanowires by means of tip-enhanced Raman scattering

Local strain and Ge content distribution in self-assembled, in-plane Ge/Si nanowires grown by combining molecular beam epitaxy and the metal-catalyst assisted-growth method were investigated by tip-enhanced Raman scattering. We show that this technique is essential to study variations of physical properties of single wires at the nanoscale, a task which cannot be achieved with conventional micro-Raman scattering. As two major findings, we report that (i) the Ge distribution in the (001) crystallographic direction is inhomogeneous, displaying a gradient with a higher Ge content close to the top surface, and (ii) in contrast, the (uncapped) wires exhibit essentially the same small residual compressive strain everywhere along the wire.

Piezoresponse force microscopy at sub-room temperatures

Piezoresponse force microscopy is demonstrated at temperatures between -80 °C and +120 °C using a commercial room temperature atomic force microscope upgraded with a home-built cooling/heating-stage. We applied temperature-ramp-synchronized piezoresponse force microscope (PFM) for tracing the temperature dependence of the formation of ferroelectric domains. The potential of our sub-room temperature PFM is demonstrated by investigating the formation and evolution of ferroelectric domains in RbHSO4 as a function of temperature and time, respectively.

Fractures of the thoracic spine in patients with minor trauma: comparison of diagnostic accuracy and dose of biplane radiography and MDCT

OBJECTIVES

To investigate the accuracy of biplane radiography in the detection of fractures of the thoracic spine in patients with minor trauma using multidetector computed tomography (MDCT) as the reference and to compare the dose of both techniques.

METHODS

107 consecutive trauma patients with suspected fractures of the thoracic spine on physical examination were included. All had undergone biplane radiography first, followed by a MDCT scan between October 2008 and October 2012. A fourfold table was used for the classification of the screening test results. Both the Chi-square test (χ(2)) and the mean dose-length product (DLP) were used to compare the diagnostic methods.

RESULTS

MDCT revealed 77 fractures in 65/107 patients (60.7%). Biplane radiography was true positive in 32/107 patients (29.9%), false positive in 19/107 patients (17.8%), true negative in 23/107 (21.5%) and false negative in 33/107 patients (30.8%), showing a sensitivity of 49.2%, a specificity of 54.7%, a positive predictive value (PPV) of 62.7%, a negative predictive value (NPV) of 41.1%, and an accuracy of 51.4%. The presence of a fracture on biplane radiography was highly statistical significant, if this was simultaneously proven by MDCT (χ(2)=7.6; p=0.01). None of the fractures missed on biplane radiography was unstable. The mean DLP on biplane radiography was 14.5mGycm (range 1.9-97.8) and on MDCT 374.6mGycm (range 80.2-871).

CONCLUSIONS

The sensitivity and the specificity of biplane radiography in the diagnosis of fractures of the thoracic spine in patients with minor trauma are low. Considering the wide availability of MDCT that is usually necessary for taking significant therapeutic steps, the indication for biplane radiography should be very restrictive.

Thermoelectric detection of spin waves

We report on the thermoelectric detection of spin waves in Permalloy stripes via the anomalous Nernst effect. Spin waves are locally excited by a dynamic magnetic field generated from a microwave current flowing in a coplanar waveguide placed on top of a Permalloy stripe, which acts as a waveguide for spin waves. Electric contacts at the ends of the Permalloy stripe measure a dc voltage generated along the stripe. Magnetic field sweeps for different applied microwave frequencies reveal, with a remarkable signal-to-noise ratio, an electric voltage signature characteristic of spin-wave excitations. The symmetry of the signal with respect to the applied magnetic field direction indicates that the anomalous Nernst effect is responsible; Seebeck effects, anisotropic magnetoresistance, and voltages due to spin-motive forces are excluded. The dissipation of spin waves causes local heating that drains into the substrate, giving rise to a temperature gradient perpendicular to the sample plane, resulting in the anomalous Nernst voltage.

Association of nutritional status, plasma, albumin levels and pulmonary function in cystic fibrosis

BACKGROUND & AIMS

Malnutrition is related with pulmonary disease. The aim was to analyze the association of lung function respectively to nutritional status, identified pulmonary pathogens and socioeconomic condition of patients attending a pediatric CF reference center.

METHODS

Cross-sectional study performed with CF patients aged 6 to 18 years attending a CF-Center in southern Brazil. Nutritional status, plasma albumin level and pulmonary bacterial colonization were assessed. The outcome studied was forced expiratory volume in 1 second (FEV1).

RESULTS

Eighty-five patients were included in this study. FEV1 was significantly associated with body mass index (BMI) percentiles, plasma albumin level and methicillin resistant Staphylococcus aureus (MRSA) pulmonary colonization. Regression analysis showed that BMI below the 10th percentile was associated with a 25.58% drop in FEV1, and plasma albumin levels equal to or lower than 4.1 mg/dL was associated with 18.6% FEV1 reduction. FEV1 was 14.4% lower in the MRSA infected patients. Plasma albumin of 4.25 mg/dL predicted FEV1 of 60% with 76.9% sensitivity and 72.2% specificity, and 85.7% accuracy. The socioeconomic status was not association with pulmonary function.

CONCLUSION

BMI below the 10th percentile and albumin below 4.1 mg/dL were predictors of low FEV1. Chronic MRSA infection was associated with lower FEV1. Longitudinal studies may better complement these results.