Mathematical models of magnetospheric convection and its coupling to the ionosphere

Mathematical models of magnetospheric convection and its coupling to ionospher

Dual spacecraft observations of lobe magnetic field perturbations before, during and after plasmoid release

This study examines a data set returned by IMP 8 and Geotail on January 29, 1995 during a substorm which resulted in the ejection of a plasmoid. The two spacecraft (s/c) were situated in the north lobe of the tail and both observed a traveling compression region (TCR). We show that in this instance dual s/c measurements can be used to model all three dimensions of the underlying plasmoid and to estimate its rate of expansion. For this event plasmoid dimensions of ΔX ∼18, ΔY ∼30, and ΔZ ∼10 Re are determined from the IMP 8 and Geotail observations. Furthermore, a factor of ∼2 increase in the amplitude of the TCR occurred in the 1.5 min it took to move from IMP 8 to Geotail. Modeled using conservation of magnetic flux, this increase in lobe compression implies that the underlying plasmoid was expanding at a rate of ∼140 km/s. Finally, a reconfiguration of the lobe magnetic field followed plasmoid ejection which moved magnetic flux tubes into the wake behind the plasmoid where they would become available to feed the reconnection region

Cluster electric current density measurements within a magnetic flux rope in the plasma sheet

[1] On August 22, 2001 all 4 Cluster spacecraft nearly simultaneously penetrated a magnetic flux rope in the tail. The flux rope encounter took place in the central plasma sheet, beta(i) similar to1-2, near the leading edge of a bursty bulk flow. The "time-of-flight'' of the flux rope across the 4 spacecraft yielded V-x similar to 700 km/s and a diameter of similar to1 R-e. The speed at which the flux rope moved over the spacecraft is in close agreement with the Cluster plasma measurements. The magnetic field profiles measured at each spacecraft were first modeled separately using the Lepping-Burlaga force-free flux rope model. The results indicated that the center of the flux rope passed northward ( above) s/c 3, but southward (below) of s/c 1, 2 and 4. The peak electric currents along the central axis of the flux rope predicted by these single-s/c models were similar to15-19 nA/m(2). The 4-spacecraft Cluster magnetic field measurements provide a second means to determine the electric current density without any assumption regarding flux rope structure. The current profile determined using the curlometer technique was qualitatively similar to those determined by modeling the individual spacecraft magnetic field observations and yielded a peak current density of 17 nA/m(2) near the central axis of the rope. However, the curlometer results also showed that the flux rope was not force-free with the component of the current density perpendicular to the magnetic field exceeding the parallel component over the forward half of the rope, perhaps due to the pressure gradients generated by the collision of the BBF with the inner magnetosphere. Hence, while the single-spacecraft models are very successful in fitting flux rope magnetic field and current variations, they do not provide a stringent test of the force-free condition

Dietary intake, lung function and airway inflammation in Mexico City school children exposed to air pollutants

<p>Abstract</p> <p>Introduction</p> <p>Air pollutant exposure has been associated with an increase in inflammatory markers and a decline in lung function in asthmatic children. Several studies suggest that dietary intake of fruits and vegetables might modify the adverse effect of air pollutants.</p> <p>Methods</p> <p>A total of 158 asthmatic children recruited at the Children's Hospital of Mexico and 50 non-asthmatic children were followed for 22 weeks. Pulmonary function was measured and nasal lavage collected and analyzed every 2 weeks. Dietary intake was evaluated using a 108-item food frequency questionnaire and a fruit and vegetable index (FVI) and a Mediterranean diet index (MDI) were constructed. The impact of these indices on lung function and interleukin-8 (IL-8) and their interaction with air pollutants were determined using mixed regression models with random intercept and random slope.</p> <p>Results</p> <p>FVI was inversely related to IL-8 levels in nasal lavage (p < 0.02) with a significant inverse trend (test for trend p < 0.001), MDI was positively related to lung function (p < 0.05), and children in the highest category of MDI had a higher FEV₁(test for trend p < 0.12) and FVC (test for trend p < 0.06) than children in the lowest category. A significant interaction was observed between FVI and ozone for FEV₁and FVC as was with MDI and ozone for FVC. No effect of diet was observed among healthy children.</p> <p>Conclusion</p> <p>Our results suggest that fruit and vegetable intake and close adherence to the Mediterranean diet have a beneficial effect on inflammatory response and lung function in asthmatic children living in Mexico City.</p

New Perspectives on Substorm Injections

There has been significant progress in understanding substorm injections since the Third International Conference on Substorms in 1996. Progress has come from a combination of new theories, quantitative modeling, and observations--particularly multi-satellite observations. There is now mounting evidence that fast convective flows are the mechanism that directly couples substorm processes in the mid tail, where reconnection occurs, with substorm processes the inner magnetosphere where Pi2 pulsations, auroral breakups, and substorm injections occur. This paper presents evidence that those flows combined with an earthward-propagating compressional wave are responsible for substorm injections and discusses how that model can account for various substorm injection signatures

Effect of the anti-retroviral drug, rilpivirine, on human subcutaneous adipose cells and its nutritional management using quercetin

Rilpivirine, a recently developed drug of choice for initial treatment of HIV-1 infection, can greatly reduce HIV-related inflammation, but in turn, may be associated with adverse secondary effects, including disturbances in lipid metabolism and ultimately in adipose tissue distribution and function. In recent years, research findings on the benefits of anti-oxidant foods and supplements have been employed in counter-acting both oxidative stress as well as inflammation in order to reduce the adverse side effects of anti-retroviral therapy. One such natural flavonoid which possesses anti-inflammatory and anti-oxidative properties is quercetin. This study investigated the effect of quercetin in overcoming the side effects incurred due to rilpivirine administration. The results show substantial reduction in the accumulation of triglyceride levels in a dose- and time- dependent manner for adipose cells treated with either rilpivirine or quercetin alone and in combination, as evidenced by morphological pictures and quantitative measurement of triglycerides throughout the differentiation process. Levels of inflammatory markers such as resistin and IL-8 were increased as compared to the untreated cells. No significant changes in leptin were observed on treatment of adipose cells with rilpivirine alone and its levels were almost comparable to control. Levels of oxidative markers like superoxide dismutase, catalase and glutathione were also decreased. Treatment with quercetin showed a decrease in the inflammatory status and an increase in the oxidative status of adipose cells, thereby, exhibiting its anti-inflammatory and anti-oxidative properties. However, further assessment of lipid metabolism and adipose tissue function in patients administered with rilpivirine-based regimes is advisable considering that totally neutral effects of rilpivirine on lipid homeostasis cannot be anticipated from the current study in vitro. It is concluded that rilpivirine causes an anti-adipogenic and pro-inflammatory response pattern but only at high concentrations, whereas quercetin has been observed to decrease inflammation and restore the levels of anti-oxidant enzyme

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe