The correspondence between small-scale coronal structures and the evolving solar magnetic field

Solar coronal bright points, first identified in soft X-rays as X-ray Bright Points (XBPs), are compact, short lived and associated with small bipolar magnetic flux. Contradictory studies have suggested that XBPs are either a primary signature of the emerging flux spectrum of the quiet Sun, or that they are representative of the disappearance of pre-existing flux. Results are presented using coordinated data obtained during recent X-ray sounding rocket flights on 15 August and 11 December 1987 to determine the correspondence of XBPs with time-series, ground based observations of evolving bipolar magnetic structures, He-I dark points, and the network. The results are consistent with the view that coronal bright points are more likely to be associated with the annihilation of pre-existing flux than with emerging flux

The observation of possible reconnection events in the boundary changes of solar coronal holes

Coronal holes are large scale regions of magnetically open fields which are easily observed in solar soft X-ray images. The boundaries of coronal holes are separatrices between large scale regions of open and closed magnetic fields where one might expect to observe evidence of solar magnetic reconnection. Previous studies by Nolte and colleagues using Skylab X-ray images established that large scale (greater than or equal to 9 x 10(4) km) changes in coronal hole boundaries were due to coronal processes, i.e., magnetic reconnection, rather than to photospheric motions. Those studies were limited to time scales of about one day, and no conclusion could be drawn about the size and time scales of the reconnection process at hole boundaries. Sequences of appropriate Skylab X-ray images were used with a time resolution of about 90 min during times of the central meridian passages of the coronal hole labelled Coronal Hole 1 to search for hole boundary changes which can yield the spatial and temporal scales of coronal magnetic reconnection. It was found that 29 of 32 observed boundary changes could be associated with bright points. The appearance of the bright point may be the signature of reconnection between small scale and large scale magnetic fields. The observed boundary changes contributed to the quasi-rigid rotation of Coronal Hole 1

Plasma properties of hot coronal loops utilizing coordinated SMM and solar research rocket observations

Three improvements in photographic x-ray imaging techniques for solar astronomy are presented. The testing and calibration of a new film processor was conducted; the resulting product will allow photometric development of sounding rocket flight film immediately upon recovery at the missile range. Two fine grained photographic films were calibrated and flight tested to provide alternative detector choices when the need for high resolution is greater than the need for high sensitivity. An analysis technique used to obtain the characteristic curve directly from photographs of UV solar spectra were applied to the analysis of soft x-ray photographic images. The resulting procedure provides a more complete and straightforward determination of the parameters describing the x-ray characteristic curve than previous techniques. These improvements fall into the category of refinements instead of revolutions, indicating the fundamental suitability of the photographic process for x-ray imaging in solar astronomy

Solar X-ray Astronomy Sounding Rocket Program

Several broad objectives were pursued by the development and flight of the High Resolution Soft X-Ray Imaging Sounding Rocket Payload, followed by the analysis of the resulting data and by comparison with both ground based and space based observations from other investigators. The scientific objectives were: to study the thermal equilibrium of active region loop systems by analyzing the X-ray observations to determine electron temperatures, densities, and pressures; by recording the changes in the large scale coronal structures from the maximum and descending phases of Cycle 21 to the ascending phase of Cycle 22; and to extend the study of small scale coronal structures through the minimum of Cycle 21 with new emphasis on correlative observations

Low prevalence of Plasmodium falciparum antigenaemia among asymptomatic HAART-treated adults in an urban cohort in Uganda

<p>Abstract</p> <p>Background</p> <p>Presumptive treatment of malaria is common practice in malaria endemic resource-limited settings. With the changing epidemiology of malaria and the introduction of artemisinin-based combination therapy (ACT), there is increasing need for parasite-based malaria case management to prevent unnecessary use of anti-malarial medicines, improve patient care in parasite-positive patients and identify parasite-negative patients in whom another diagnosis must be sought. Although parasitological confirmation by microscopy or alternatively by malaria rapid diagnostic tests (RDTs) is recommended in all patients suspected of malaria before treatment, gaps remain in the implementation of this policy in resource-limited settings. There is need to evaluate the use of RDTs among highly active anti-retroviral therapy (HAART)-treated people living with HIV (PLHIV).</p> <p>Methods</p> <p>Within an urban prospective observational research cohort of 559 PLHIV initiated on HAART and cotrimoxazole prophylaxis between April, 2004 and April, 2005, 128 patients with sustained HIV-RNA viral load < 400 copies/ml for four years were evaluated, in a cross-sectional study, for asymptomatic malaria infection using a histidine-rich protein-2 (HRP-2) RDT to detect <it>Plasmodium falciparum </it>antigen in peripheral blood. Patients with positive RDT results had microscopy performed to determine the parasite densities and were followed for clinical signs and symptoms during the subsequent six months.</p> <p>Results</p> <p>Of the 128 asymptomatic patients screened, only 5 (4%) had asymptomatic <it>P. falciparum </it>antigenaemia. All the patients with positive HRP2 RDT results showed malaria parasites on thick film with parasite densities ranging from 02-15 malaria parasites per high power field. None of the patients with positive RDT results reported signs and symptoms of malaria infection during the subsequent six months.</p> <p>Conclusions</p> <p>In an urban area of low to moderate stable malaria transmission, there was low HRP2 P. <it>falciparum </it>antigenaemia among PLHIV after long-term HAART and cotrimoxazole prophylaxis. Parasite-based malaria diagnosis (PMD) is recommended among PLHIV that are on long-term anti-retroviral therapy. RDTs should be utilized to expand PMD in similar settings where microscopy is unavailable.</p

Correspondence between solar fine-scale structures in the corona, transition region, and lower atmosphere from collaborative observations

The Soft X-Ray Imaging Payload and the High Resolution Telescope and Spectrograph (HRTS) instrument were launched from White Sands on 11 December 1987 in coordinated sounding rocket flights to investigate the correspondence of coronal and transition region structures, especially the relationship between X-ray bright points (XBPs) and transition region small spatial scale energetic events. The coaligned data from X-ray images are presented along with maps of sites of transition region energetic events observed in C IV (100,000 K), HRTS 1600 A spectroheliograms of the T sub min region and ground based magnetogram and He I 10830 A images

Increasing Food Production in Drylands Using Agrivoltaics

In the desert, native plants respond to the hottest part of the day by either closing their stomata, which would stop photosynthesis, or by simply reducing their photosynthesis rates due to heat stress. Soil water resources are also impacted due to significant evaporation. If plants have more shade during the day, will they photosynthesize more in the afternoon than plants without shade? Will these plants with shade transpire less, and thus need to be watered less? This study takes a look at plants which have grown under a photovoltaics array (a new agriculture practice called agrivoltaics) as well as plants which have grown in the open (modeling traditional agriculture practices). It was hypothesized the agrivoltaics practice will benefit plants by providing them shade and retaining soil moisture during the day as well as benefiting the photovoltaics by keeping them cooler to increase their efficiency. This study was designed to determine whether growing under the photovoltaic panels is beneficial, by collecting and analyzing data on photosynthesis (carbon uptake) and transpiration (water loss) rates of 8+ different species. These measurements will help answer which plants are best suited for being planted in an agrivoltaics installation

Assessing the presence of Wuchereria bancrofti in vector and human populations from urban communities in Conakry, Guinea

The Global Programme to Eliminate Lymphatic Filariasis was launched in 2000 with the goal of interrupting transmission of lymphatic filariasis (LF) through multiple rounds of mass drug administration (MDA). In Guinea, there is evidence of ongoing LF transmission, but little is known about the most densely populated parts of the country, including the capital Conakry. In order to guide the LF control and elimination efforts, serological and entomological surveys were carried out to determine whether or not LF transmission occurs in Conakry.; The prevalence of circulating filarial antigen (CFA) of Wuchereria bancrofti was assessed by an immuno-chromatography test (ICT) in people recruited from all five districts of Conakry. Mosquitoes were collected over a 1-year period, in 195 households in 15 communities. A proportion of mosquitoes were analysed for W. bancrofti, using dissection, loop-mediated isothermal amplification (LAMP) assay and conventional polymerase chain reaction (PCR).; CFA test revealed no infection in the 611 individuals examined. A total of 14,334 mosquitoes were collected; 14,135 Culex (98.6 %), 161 Anopheles (1.1 %) and a few other species. Out of 1,312 Culex spp. (9.3 %) and 51 An. gambiae (31.7 %) dissected, none was infected with any stage of the W. bancrofti parasite. However, the LAMP assay revealed that 1.8 % of An. gambiae and 0.31 % of Culex spp. were positive, while PCR determined respective prevalences of 0 % and 0.19 %.; This study revealed the presence of W. bancrofti DNA in mosquitoes, despite the apparent absence of infection in the human population. Although MDA interventions are not recommended where the prevalence of ICT is below 1 %, the entomological results are suggestive of the circulation of the parasite in the population of Conakry. Therefore, rigorous surveillance is still warranted so that LF transmission in Conakry would be identified rapidly and adequate responses being implemented

Carrier generation and transport in bulk heterojunction films processed with 1,8-octanedithiol as a processing additive

Improved performance of polymer-based solar cells based on poly[2,6-(4,4-bis-(2-ethylhexyl)- 4H -cyclopenta[2,1-b;3,4- b???] dithiophene)-alt-4,7-(2,1,3-benzo-thiadiazole)] PCPDTBT has been obtained by using 1,8-octanedithiol (ODT) as a processing additive in the polymer solution used to spin cast the bulk heterojunction films. Although ultrafast spectroscopy studies indicate that the carrier losses are reduced in the films processed with ODT [similar to the reduced carrier losses after thermal annealing of bulk heterojunction (BHJ) materials made from P3HT:PCBM], the magnitude of the reduction is not sufficient to explain the observed factor of 2 increase in the power conversion efficiency. From the analysis of carrier transport in field effect transistors, we find increased electron mobility in the PCPDTBT: PC70 BM composites when fabricated with ODT, which is indicative of enhanced connectivity of PC70 BM networks. The improved electron mobility appears to be the primary origin of the improved power conversion efficiency in BHJ films.open453

ESD Terms and Definitions (Version 12)

Basic terms related to engineering system