Sunspot rotation. I. A consequence of flux emergence

Context. Solar eruptions and high flare activity often accompany the rapid rotation of sunspots. The study of sunspot rotation and the mechanisms driving this motion are therefore key to our understanding of how the solar atmosphere attains the conditions necessary for large energy release. Aims. We aim to demonstrate and investigate the rotation of sunspots in a 3D numerical experiment of the emergence of a magnetic flux tube as it rises through the solar interior and emerges into the atmosphere. Furthermore, we seek to show that the sub-photospheric twist stored in the interior is injected into the solar atmosphere by means of a definitive rotation of the sunspots. Methods. A numerical experiment is performed to solve the 3D resistive magnetohydrodynamic (MHD) equations using a Lagrangian-Remap code. We track the emergence of a toroidal flux tube as it rises through the solar interior and emerges into the atmosphere investigating various quantities related to both the magnetic field and plasma. Results. Through detailed analysis of the numerical experiment, we find clear evidence that the photospheric footprints or sunspots of the flux tube undergo a rotation. Significant vertical vortical motions are found to develop within the two polarity sources after the field emerges. These rotational motions are found to leave the interior portion of the field untwisted and twist up the atmospheric portion of the field. This is shown by our analysis of the relative magnetic helicity as a significant portion of the interior helicity is transported to the atmosphere. In addition, there is a substantial transport of magnetic energy to the atmosphere. Rotation angles are also calculated by tracing selected fieldlines; the fieldlines threading through the sunspot are found to rotate through angles of up to 353 degrees over the course of the experiment

Dielectric properties measurements of brown and white adipose tissue in rats from 0.5 to 10 GHz

Brown adipose tissue (BAT) plays an important role in whole body metabolism and with appropriate stimulus could potentially mediate weight gain and insulin sensitivity. Although imaging techniques are available to detect subsurface BAT, there are currently no viable methods for continuous acquisition of BAT energy expenditure. Microwave (MW) radiometry is an emerging technology that allows the quantification of tissue temperature variations at depths of several centimeters. Such temperature differentials may be correlated with variations in metabolic rate, thus providing a quantitative approach to monitor BAT metabolism. In order to optimize MW radiometry, numerical and experimental phantoms with accurate dielectric properties are required to develop and calibrate radiometric sensors. Thus, we present for the first time, the characterization of relative permittivity and electrical conductivity of brown (BAT) and white (WAT) adipose tissues in rats across the MW range 0.5-10GHz. Measurements were carried out in situ and post mortem in six female rats of approximately 200g. A Cole-Cole model was used to fit the experimental data into a parametric model that describes the variation of dielectric properties as a function of frequency. Measurements confirm that the dielectric properties of BAT (εr = 14.0-19.4, σ = 0.3-3.3S/m) are significantly higher than those of WAT (εr = 9.1-11.9, σ = 0.1-1.9S/m), in accordance with the higher water content of BAT

Older female children experience poorer quality of life when levels of perceived racial bias are high

Background: Individuals with sickle cell disease (SCD) experience significant health problems that result in unpredictable pain episodes and frequent healthcare utilization. Disparities in clinical care and emergency room visits in which medical providers mistrust the severity of reported pain symptoms may contribute to health-related stigma. In addition to stigma related to seeking care for acute pain, racism is a source of stigma with associated systemic inequities for this majority Black population. There is currently limited research into the effects of health-related stigma and racial bias on the underserved SCD population; however, the small body of research has found barriers to healthcare utilization, greater pain burden, and increased emotional distress. There is little known about the influence of health-related stigma and racial bias on quality of life (QOL) of children with SCD. The present study assessed these relationships, and additionally, we sought to understand whether there were differences in this relationship with regards to demographic factors (e.g., age, gender). / Methods: Data was collected from African-American children with SCD aged 8 - 16 years (57% male, 63% HbSS) who received care at a medical center in the United States. Sixty-three percent of children were receiving chronic transfusion therapy or pheresis and 37% were receiving hydroxyurea therapy. Children completed the Childhood Stigma Scale (adapted for SCD), the Child Perceptions of Racism in Children and Youth scale (PRaCY), and the Pediatric Quality of Life Inventory for SCD (PedsQL). Caregivers provided demographic information. / Results: We first assessed whether age, gender, and health-related stigma predicted QOL and demonstrated a significant overall model, F(7, 22) = 4.59, p = .003, r = .46. Health-related stigma (p = .007) predicted QOL, but neither age or gender were significant predictors. The next model assessed whether age, gender, and racial bias predicted QOL and demonstrated a significant overall model, F(7, 22) = 4.59, p < .001, r = .52. Specifically, age (p = .03), but neither gender or racial bias were significant predictors. Of interest, there was a significant interaction between age, gender, and racial bias (p = .02), which indicated that males generally had higher QOL that did not differ as a function of racial bias or age. Similarly, females who reported low levels of racial bias had higher QOL that did not differ as a function of age. In contrast, females who reported high levels of racial bias had QOL that differed as a function of age. Specifically, older female children who reported high levels of perceived racial bias had poorer QOL (see Figure 1)

The influence of perceived racial bias and health-related stigma on quality of life among children with sickle cell disease

OBJECTIVES: Individuals with sickle cell disease (SCD) experience significant health problems that may result in unpredictable pain episodes and frequent healthcare utilization. Disparities in clinical care may contribute to health-related stigma and racial bias for this majority African-American/Black population. There is less known about the influence of health-related stigma and racial bias on the health-related quality of life (HRQOL) of children with SCD. In the present study, we assessed these relationships and identified differences across demographic factors (i.e. age, gender). DESIGN: Data was collected from African American children with SCD aged 8–16 years (57% male, 63% HbSS). Children completed the Childhood Stigma Scale (adapted for SCD), the Child Perceptions of Racism in Children and Youth scale, and the Pediatric Quality of Life Inventory Sickle Cell Disease Module. Caregivers provided demographic information. RESULTS: In the first regression model, health-related stigma (p = .007) predicted HRQOL, but neither age nor gender were significant predictors. In the second regression model, age (p = .03) predicted HRQOL, but neither gender nor racial bias were significant predictors. Of interest, there was a significant interaction between age, gender, and racial bias (p = .02). Specifically, older girls who reported high levels of perceived racial bias had poorer HRQOL. CONCLUSIONS: Our study highlights the need for increased awareness about the effects of health-related stigma and racial bias on HRQOL for children with SCD, particularly for older girls who endorse racial bias. Our findings will guide future stigma and bias reduction interventions that may meet the needs of older girls with SCD

Motion-light parametric amplifier and entanglement distributor

We propose a scheme for entangling the motional mode of a trapped atom with a propagating light field via a cavity-mediated parametric interaction. We then show that if this light field is subsequently coupled to a second distant atom via a cavity-mediated linear-mixing interaction, it is possible to transfer the entanglement from the light beam to the motional mode of the second atom to create an EPR-type entangled state of the positions and momenta of two distantly-separated atoms.Comment: 9 pages, 8 figures, REVTe

Dark States and Interferences in Cascade Transitions of Ultra-Cold Atoms in a Cavity

We examine the competition among one- and two-photon processes in an ultra-cold, three-level atom undergoing cascade transitions as a result of its interaction with a bimodal cavity. We show parameter domains where two-photon transitions are dominant and also study the effect of two-photon emission on the mazer action in the cavity. The two-photon emission leads to the loss of detailed balance and therefore we obtain the photon statistics of the cavity field by the numerical integration of the master equation. The photon distribution in each cavity mode exhibits sub- and super- Poissonian behaviors depending on the strength of atom-field coupling. The photon distribution becomes identical to a Poisson distribution when the atom-field coupling strengths of the modes are equal.Comment: 15 pages including 7 figures in Revtex, submitted to PR

New variable separation approach: application to nonlinear diffusion equations

The concept of the derivative-dependent functional separable solution, as a generalization to the functional separable solution, is proposed. As an application, it is used to discuss the generalized nonlinear diffusion equations based on the generalized conditional symmetry approach. As a consequence, a complete list of canonical forms for such equations which admit the derivative-dependent functional separable solutions is obtained and some exact solutions to the resulting equations are described.Comment: 19 pages, 2 fig

Src-mediated coupling of focal adhesion kinase to integrin αvβ5 in vascular endothelial growth factor signaling

Vascular endothelial growth factor (VEGF) promotes vascular permeability (VP) and neovascularization, and is required for development. We find that VEGF-stimulated Src activity in chick embryo blood vessels induces the coupling of focal adhesion kinase (FAK) to integrin αvβ5, a critical event in VEGF-mediated signaling and biological responsiveness. In contrast, FAK is constitutively associated with β1 and β3 integrins in the presence or absence of growth factors. In cultured endothelial cells, VEGF, but not basic fibroblast growth factor, promotes the Src-mediated phosphorylation of FAK on tyrosine 861, which contributes to the formation of a FAK/αvβ5 signaling complex. Moreover, formation of this FAK/αvβ5 complex is significantly reduced in pp60c-src-deficient mice. Supporting these results, mice deficient in either pp60c-src or integrin β5, but not integrin β3, have a reduced VP response to VEGF. This FAK/αvβ5 complex was also detected in epidermal growth factor-stimulated epithelial cells, suggesting a function for this complex outside the endothelium. Our findings indicate that Src can coordinate specific growth factor and extracellular matrix inputs by recruiting integrin αvβ5 into a FAK-containing signaling complex during growth factor–mediated biological responses

Comparative compositions of grain of tritordeum, durum wheat and bread wheat grown in multi-environment trials

Three genotypes each of bread wheat, durum wheat and tritordeum were grown in randomized replicated field trials in Andalusia (Spain) for two years and wholemeal flours analysed for a range of components to identify differences in composition. The contents of all components that were determined varied widely between grain samples of the individual species and in most cases also overlapped between the three species. Nevertheless, statistically significant differences between the compositions of the three species were observed. Notably, tritordeum had significantly higher contents of protein, some minerals (magnesium and iron), total phenolics and methyl donors. Tritordeum also had higher levels of total amino acids (but not asparagine) and total sugars, including raffinose. By contrast, bread wheat and tritordeum had similar contents of the two major dietary fibre components in white flour, arabinoxylan and β-glucan, with significantly lower contents in durum wheat

A position-momentum EPR state of distantly-separated trapped atoms

We propose a scheme for preparing an EPR state in position and momentum of a pair of distantly-separated trapped atoms. The scheme utilizes the entangled light fields output from a nondegenerate optical parametric amplifier. Quantum state exchange between these fields and the motional states of the trapped atoms is accomplished via interactions in cavity QED.Comment: 5 pages, 2 figures, submitted to Phys. Rev.