The effects of transients on photospheric and chromospheric power distributions

We have observed a quiet Sun region with the Swedish 1-meter Solar Telescope (SST) equipped with CRISP Imaging SpectroPolarimeter. High-resolution, high-cadence, H$\alpha$ line scanning images were taken to observe different layers of the solar atmosphere from the photosphere to upper chromosphere. We study the distribution of power in different period-bands at different heights. Power maps of the upper photosphere and the lower chromosphere show suppressed power surrounding the magnetic-network elements, known as "magnetic shadows". These also show enhanced power close to the photosphere, traditionally referred to as "power halos". The interaction between acoustic waves and inclined magnetic fields is generally believed to be responsible for these two effects. In this study we explore if small-scale transients can influence the distribution of power at different heights. We show that the presence of transients, like mottles, Rapid Blueshifted Excursions (RBEs) and Rapid Redshifted Excursions (RREs), can strongly influence the power-maps. The short and finite lifetime of these events strongly affects all powermaps, potentially influencing the observed power distribution. We show that Doppler-shifted transients like RBEs and RREs that occur ubiquitously, can have a dominant effect on the formation of the power halos in the quiet Sun. For magnetic shadows, transients like mottles do not seem to have a significant effect in the power suppression around 3 minutes and wave interaction may play a key role here. Our high cadence observations reveal that flows, waves and shocks manifest in presence of magnetic fields to form a non-linear magnetohydrodynamic system.Comment: 11 pages, 11 Figures, 4 movies (will be available online in ApJ). ApJ (accepted

Geomagnetic storm effects on GPS based navigation

The energetic events on the sun, solar wind and subsequent effects on the Earth's geomagnetic field and upper atmosphere (ionosphere) comprise space weather. Modern navigation systems that use radio-wave signals, reflecting from or propagating through the ionosphere as a means of determining range or distance, are vulnerable to a variety of effects that can degrade the performance of the navigational systems. In particular, the Global Positioning System (GPS) that uses a constellation of earth orbiting satellites are affected due to the space weather phenomena. <br><br> Studies made during two successive geomagnetic storms that occurred during the period from 8 to 12 November 2004, have clearly revealed the adverse affects on the GPS range delay as inferred from the Total Electron Content (TEC) measurements made from a chain of seven dual frequency GPS receivers installed in the Indian sector. Significant increases in TEC at the Equatorial Ionization anomaly crest region are observed, resulting in increased range delay during the periods of the storm activity. Further, the storm time rapid changes occurring in TEC resulted in a number of phase slips in the GPS signal compared to those on quiet days. These phase slips often result in the loss of lock of the GPS receivers, similar to those that occur during strong(>10 dB) L-band scintillation events, adversely affecting the GPS based navigation

Methodology development for evaluation of selective-fidelity rotorcraft simulation

This paper addressed the initial step toward the goal of establishing performance and handling qualities acceptance criteria for realtime rotorcraft simulators through a planned research effort to quantify the system capabilities of 'selective fidelity' simulators. Within this framework the simulator is then classified based on the required task. The simulator is evaluated by separating the various subsystems (visual, motion, etc.) and applying corresponding fidelity constants based on the specific task. This methodology not only provides an assessment technique, but also provides a technique to determine the required levels of subsystem fidelity for a specific task

Elasticity-mediated self-organization and colloidal interactions of solid spheres with tangential anchoring in a nematic liquid crystal

Using laser tweezers and fluorescence confocal polarizing microscopy, we study colloidal interactions of solid microspheres in the nematic bulk caused by elastic distortions around the particles with strong tangential surface anchoring. The particles aggregate into chains directed at about 30 degrees to the far field director and, at higher concentrations, form complex kinetically trapped structures. We characterize the distance and angular dependencies of the colloidal interaction forces.Comment: 6 pages, 5 figure

Visualisation of an entangled channel spin-1 system

Co-variance matrix formalism gives powerful entanglement criteria for continuous as well as finite dimensional systems. We use this formalism to study a mixed channel spin-1 system which is well known in nuclear reactions. A spin-j state can be visualized as being made up of 2j spinors which are represented by a constellation of 2j points on a Bloch sphere using Majorana construction. We extend this formalism to visualize an entangled mixed spin-1 system.Comment: 4 pages,4 figure

Association and correlation of thyroid dysfunction with anemia types in pregnant women of northern Andhra Pradesh, India

Background: Thyroid dysfunction is a common disorder in pregnancy along with anemia. But no study has evaluated the association between them. To estimate the prevalence of thyroid dysfunction and its association with anemia types in pregnant women during 1st trimester.Methods: Three hundred and eighty pregnant women with <12 weeks of gestational age were selected for the study with no history of thyroid dysfunction and anemia. All the pregnant women were classified into A, euthyroid and B, thyroid dysfunction groups. The B group was again subdivided into hypothyroid, subclinical hypothyroid (SCH), hyperthyroid according to nature of dysfunction. 5 ml of blood sample was collected from all subjects to analyse thyroid hormones and erythrocyte indices.Results: Out of 380 subjects, euthyroid was found to be 77.9%, and rest 22.1% were with thyroid dysfunction. Out of 84 thyroid dysfunction, hypothyroid was found to be 7.9%, SCH 13.9% and hyperthyroid was 0.3%. Out of 296 euthyroid women, anemia was identified in 97 pregnant women (32.8%) whereas in thyroid dysfunction women it was 43 women out of 84 (51.2%) which is a statistically significant. Significantly higher frequency of microcytic hypochromic anemia and normocytic normochromic anemia types were also found in thyroid dysfunction groups compared to euthyroid group (p<0.05). However, no significance between the thyroid dysfunction groups, Statistically significant difference was observed in the Hb concentration, RBC count, MCV, MCH and PCV between euthyroid and different thyroid dysfunction conditions (p<0.05). A statistically significant positive correlation was found between fT4 and erythrocyte indices.Conclusions: As fT4 and TSH correlated with erythrocyte indices, it is advisable to screen for thyroid dysfunction and vice versa so as to prevent the complications associated with anemia and thyroid dysfunction

Prevalence of thyroid dysfunction in pregnant women and the need for universal screening: an observational study in Northern Andhra Pradesh population

Background: The maternal thyroid dysfunction is associated with adverse outcomes such as miscarriage, preterm delivery, preeclampsia, postpartum haemorrhage in mother whereas increased risk of impaired neurological development in foetus. The present study was designed with an aim to determine the prevalence of thyroid dysfunction and the need for universal screening in pregnant women.Methods: Three hundred and eighty pregnant women between 8-36 weeks of gestation with age group 20-32 years were recruited. Serum free T3, free T4 and TSH levels were assayed by chemiluminescence method. The pregnant women were classified into euthyroid, subclinical hypothyroid (SH), overt hypothyroid (OH) and overt hyperthyroid groups based on the results obtained in the study.Results: In the present study, the mean ± SD age (in years) and BMI of all pregnant women was 23.9±3.9 and 22.9±1.6 respectively. The maternal age was high in OH and overt hyperthyroid and was statistically significant (p&lt;0.05). Similarly, women with high BMI were prone to OH than normal BMI (p&lt;0.05). The prevalence of thyroid dysfunction was found to be 18.7%. The prevalence of hypothyroidism was 17.4% in which the SH was 13.4% and overt hypothyroidism 3.9%, but overt hyperthyroidism was 1.3%. TSH levels increased with the advancement of gestational age from 2.72±1.85 in first trimester to 3.4±2.05 µIU/mL in third trimester, and the difference was statistically significant (p&lt;0.05). Finally, it was also noticed that the prevalence of raised TSH in high-risk pregnant women was high compared to low-risk women (35.6% vs 5.1%) relative risk (RR) 7.64, 95% confidence interval (CI) 4.62-12.65, (p&lt;0.0001). However, 14 out of 51 (27.5%) with SH were in low-risk group.Conclusions: The present study states that the prevalence of thyroid dysfunction was 18.7% and also emphasizes the importance of screening all pregnant women for thyroid dysfunction rather than targeted high-risk pregnant women to prevent both maternal and fetal morbidity