Magnetic Tension of Sunspot Fine Structures

The equilibrium structure of sunspots depends critically on its magnetic topology and is dominated by magnetic forces. Tension force is one component of the Lorentz force which balances the gradient of magnetic pressure in force-free configurations. We employ the tension term of the Lorentz force to clarify the structure of sunspot features like penumbral filaments, umbral light bridges and outer penumbral fine structures. We compute vertical component of tension term of Lorentz force over two active regions namely NOAA AR 10933 and NOAA AR 10930 observed on 05 January 2007 and 12 December 2006 respectively. The former is a simple while latter is a complex active region with highly sheared polarity inversion line (PIL). The vector magnetograms used are obtained from Hinode(SOT/SP). We find an inhomogeneous distribution of tension with both positive and negative signs in various features of the sunspots. The existence of positive tension at locations of lower field strength and higher inclination is compatible with the uncombed model of the penumbral structure. Positive tension is also seen in umbral light bridges which could be indication of uncombed structure of the light bridge. Likewise, the upward directed tension associated with bipolar regions in the penumbra could be a direct confirmation of the sea serpent model of penumbral structures. Upward directed tension at the PIL of AR 10930 seems to be related to flux emergence. The magnitude of the tension force is greater than the force of gravity in some places, implying a nearly force-free configuration for these sunspot features. From our study, magnetic tension emerges as a useful diagnostic of the local equilibrium of the sunspot fine structures.Comment: 06 pages, 6 figures; Accepted for publication in the Astronomy & Astrophysics as a "Letter to the Editor

Circulating interleukin-10 and risk of cardiovascular events: a prospective study in the elderly at risk

<p><b>Objective:</b> The goal of this study was to examine the association of the antiinflammatory interleukin-10 (IL-10) with risk of cardiovascular disease (CVD).</p> <p><b>Methods and Results:</b> In the PROSPER (PROspective Study of Pravastatin in the Elderly at Risk) cohort, we related baseline concentrations of circulating IL-10 to risk of CVD events in a nested case (n=819)-control (n=1618) study of 3.2 years of follow-up. Circulating IL-10 showed few strong associations with classical risk factors but was positively correlated with IL-6 and C-reactive protein. IL-10 was positively associated with risk of CVD events (odds ratio [OR] 1.17, 95% CI 1.05 to 1.31 per unit increase in log IL-10) after adjusting for classical risk factors and C-reactive protein. Furthermore, IL-10 was associated more strongly with CVD risk among those with no previous history of CVD (OR 1.42, 95% CI 1.18 to 1.70), compared with those with previous CVD (OR 1.04, 95% CI 0.90 to 1.19; P=0.018). Overall, IL-10 showed a modest ability to add discrimination to classical risk factors (C-statistic +0.005, P=0.002).</p> <p><b>Conclusion:</b> Baseline circulating levels of the antiinflammatory IL-10 are positively associated with risk of CVD among the elderly without prior CVD events, although the association is less evident in those with a history of CVD. Additional epidemiological and mechanistic studies investigating the role of IL-10 in CVD are warranted.</p&gt

On the estimate of magnetic non-potentiality of sunspots derived using Hinode SOT/SP observations: Effect of polarimetric noise

The accuracy of Milne-Eddington (ME) inversions, used to retrieve the magnetic field vector, depends upon the signal-to-noise ratio (SNR) of the spectro-polarimetric observations. The SNR in real observations varies from pixel to pixel, therefore the accuracy of the field vector also varies over the map. The aim of this work is to study the effect of polarimetric noise on the inference of magnetic field vector and the magnetic non-potentiality of a real sunspot. To this end, we use Hinode SOT/SP vector magnetogram of a real sunspot NOAA 10933 as an input to generate synthetic Stokes profiles under ME model assumptions. We then add normally-distributed polarimetric noise of the level 0.5\% of continuum intensity to these synthetic profiles and invert them again using ME code. This process is repeated 100 times with different realizations of noise. It is found that within most of the sunspot area (> 90% area) the spread in the (i) field strength is less than 8 Gauss, (ii) field inclination is less than 1 degree, and (iii) field azimuth is less than 5 degrees. Further, we determine the uncertainty in the magnetic non-potentiality of a sunspot as determined by the force-free parameter alpha_g and Spatially Averaged Signed Shear Angle (SASSA). It is found that for the sunspot studied here these parameters are alpha_g = -3.5 +/- 0.37 (x 10^{-9} m^{-1}) and SASSA = -1.68 +/- 0.014 degrees. This suggests that the SASSA is a less dispersion non-potentiality parameter as compared to alpha_g. Further, we examine the effect of increasing noise levels viz. 0.01, 0.1, 0.5 and 1% of continuum intensity and find that SASSA is less vulnerable to noise as compared to alpha_g parameter.Comment: Astrophysical Journal (In Press) 29 pages, 5 figures (scatterplots do not appear in soft-copy but appear on laser-printer

Responsiveness of the innate immune system and glucose concentrations in the oldest old

Abstract Patients with diabetes mellitus show in-creased risk of infectious disease as well as dis-turbances in innate immunity. In critical care settings, hyperglycemia is associated with increased risk of sepsis. It is unclear whether elevated glucose concen-trations and innate immunity are associated in a non-clinical setting. We aimed to assess the association between glucose concentrations and innate immune response in the oldest old, who are at increased risk of both disturbed glucose metabolism as well as infec-tious disease. This study was part of the Leiden 85-plus Study. In 562 subjects aged 85 years old of the general population, venous blood samples were taken for measurement of morning glucose, C-reactive protein (CRP) and glycated hemoglobin (HbA1c). The innate immune response was assessed by performing ex vivo whole blood lipopolysaccharide (LPS) stimulation for production capacity of tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), interleukin 1-beta (IL1-β), interleukin 10 (IL-10) and interleukin 1 receptor antagonist (IL-1Ra). Using linear regression analysis, cross-sectional analysis between glucose and cytokine production capacity was performed. We found a significant negative association between glucose concentrations, but not HbA1c, and cytokine response capacity in four out of five measured cytokines (all p<0.05). Both glucose and HbA1c were positively associated with circulat-ing levels of CRP. Higher glucose concentrations in non-diabetic elderly are associated with lower innate immune response. As elderly show increased vulner-ability for disturbances in glucose metabolism as well as infectious disease, this relation could be of clinical significance

The incidence and risk factors for new onset atrial fibrillation in the PROSPER study

Aims Atrial fibrillation/flutter (AF) is the most common arrhythmia in older people. It associates with reduced exercise capacity, increased risk of stroke, and mortality. We aimed to determine retrospectively whether pravastatin reduces the incidence of AF and whether any electrocardiographic measures or clinical conditions might be risk factors for its development. Methods and results The PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) was a randomized, double-blind controlled trial that recruited 5804 individuals aged 70-82 years with a history of, or risk factors for, vascular disease. A total of 2891 were allocated to pravastatin and 2913 to placebo; mean follow-up was 3.2 years. Electrocardiograms (ECGs), which were recorded at baseline, annually thereafter, and at run-out, were processed by computer and reviewed manually. In all, 264 of 2912 (9.1%) of the placebo group and 283 of 2888 (9.8%) of the pravastatin-treated group developed AF [hazard ratio 1.08 (0.92,1.28), P = 0.35)]. Multivariate analysis showed that PR and QTc intervals, age, left ventricular hypertrophy, and ST-T abnormalities were related to development of AF after adjustment for many variables including alcohol consumption, which itself was univariately predictive of developing AF. Previous myocardial infarction on the ECG was not a risk factor. A history of vascular disease was strongly linked with developing AF but not diabetes and hypertension. Conclusion Pravastatin does not reduce the incidence of AF in older people at risk of vascular disease, at least in the short-medium term. Risk factors for AF include older age, prolongation of PR or QTc intervals, left ventricular hypertrophy, and ST-T abnormalities on the EC

CRISP Spectropolarimetric Imaging of Penumbral Fine Structure

We discuss penumbral fine structure in a small part of a pore, observed with the CRISP imaging spectropolarimeter at the Swedish 1-m Solar Telescope (SST), close to its diffraction limit of 0.16 arcsec. Milne-Eddington inversions applied to these Stokes data reveal large variations of field strength and inclination angle over dark-cored penumbral intrusions and a dark-cored light bridge. The mid-outer part of this penumbra structure shows 0.3 arcsec wide spines, separated by 1.6 arcsec (1200 km) and associated with 30 deg inclination variations. Between these spines, there are no small-scale magnetic structures that easily can be be identified with individual flux tubes. A structure with nearly 10 deg more vertical and weaker magnetic field is seen midways between two spines. This structure is co-spatial with the brightest penumbral filament, possibly indicating the location of a convective upflow from below.Comment: Accepted for publication in ApJL 17 Oct 2008. One Figure adde

Handgrip strength at midlife and familial longevity

Low handgrip strength has been linked with premature mortality in diverse samples of middle-aged and elderly subjects. The value of handgrip strength as marker of "exceptional" human longevity has not been previously explored. We postulated that the genetic influence on extreme survival might also be involved in the muscular strength determination pathway. Therefore, the objective of this study was to assess the muscle strength in a sample of middle-aged adults who are genetically enriched for exceptional survival and comparing them to a control group. We included 336 offspring of the nonagenarian from the Leiden Longevity Study who were enriched for heritable exceptional longevity, and 336 of their partners were used as controls. The Leiden Longevity study was a prospective follow up study of long-living siblings pairs together with their offspring and their partners. Handgrip strength was used as a proxy for overall muscle strength. No significant difference in handgrip strength was seen between the offspring of the nonagenarian and their partners after adjustment for potential confounders including body compositions, sum score of comorbidities, medication use, smoking and alcohol history. The main determinants of midlife handgrip strength were age, gender, total body percentage fat and relative appendicular lean mass. Although midlife handgrip strength has previously been shown to be an important prognostic indicator of survival, it is not a marker of exceptional familial longevity in middleaged adults. This finding suggests that genetic component of susceptibility to extreme survival is likely to be separate from that of muscular strength

Resolving the Azimuthal Ambiguity in Vector Magnetogram Data with the Divergence-Free Condition: Application to Discrete Data

We investigate how the divergence-free property of magnetic fields can be exploited to resolve the azimuthal ambiguity present in solar vector magnetogram data, by using line-of-sight and horizontal heliographic derivative information as approximated from discrete measurements. Using synthetic data we test several methods that each make different assumptions about how the divergence-free property can be used to resolve the ambiguity. We find that the most robust algorithm involves the minimisation of the absolute value of the divergence summed over the entire field of view. Away from disk centre this method requires the sign and magnitude of the line-of-sight derivatives of all three components of the magnetic field vector.Comment: Solar Physics, in press, 20 pages, 11 figure

Early-life environment influencing susceptibility to cytomegalovirus infection: evidence from the Leiden Longevity Study and the Longitudinal Study of Aging Danish Twins

SUMMARYHuman cytomegalovirus (CMV) is a common herpesvirus establishing lifelong persisting infection, which has been implicated in immunosenescence and mortality in the elderly. Little is known about how and when susceptibility to CMV infection is determined. We measured CMV seroprevalence in two genetically informative cohorts. From the Leiden Longevity Study (LLS) we selected long-lived sib-pairs (n=844) and their middle-aged offspring and the offspring's partners (n=1452). From the Longitudinal Study of Aging Danish Twins (LSADT) 604 (302 pairs) same-sex monozygotic (MZ) and dizygotic (DZ) twins aged 73-94 years were included (n=302 pairs). Offspring of the long-lived LLS participants had significantly lower seroprevalence of CMV compared to their partners (offspring: 42% vs. partners: 51%, P=0·003). Of 372 offspring living with a CMV-positive partner, only 58% were infected. The corresponding number for partners was 71% (P<0·001). In the LSADT, MZ and DZ twins had high and similar CMV-positive concordance rates (MZ: 90% vs. DZ: 88%, P=0·51) suggesting that shared family environment accounts for the similarity within twin pairs. Our findings suggest that susceptibility to CMV infection - even under continuous within-partnership exposure - appears to be more strongly influenced by early-life environment than by genetic factors and adult environment.Pathophysiology, epidemiology and therapy of agein