An overview of photovoltaic applications in space

An overview is given of the uses of photovoltaic (PV) power in space. The contribution of PV systems on unmanned, low Earth orbit and inner planetary missions is noted. The development of PV technology along the two paths of high efficiency and high power is discussed. The importance of increasing the service life of PV systems is covered

NAMA Negotiations in the WTO and Preference Erosion: Concerns of Bangladesh and Other Regional LDCs

The ongoing negotiations on non-agricultural market access (NAMA) in the WTO are expected to lead to substantive reductions in the tariff rates on industrial goods in both the developed and the developing countries. Although an agreement on the formula and coefficient(s) is yet to be reached, it is becoming increasingly clear that countries are moving towards a differentiated swiss-type formula with deeper cuts for higher tariffs. The July (2004) Framework Agreement stipulated that LDCs will not be required to undertake any tariff reduction commitments under the NAMA. However, LDCs are likely to suffer substantive tariff preference erosion as a consequence of NAMA negotiations since any tariff reduction by the developed countries will result in a fall in the preferential margins currently enjoyed by the LDCs under the various GSP schemes operated by the developed countries. Consequently, the competitive edge currently enjoyed by the LDCs by taking advantage of the preferential treatment under the various GSP schemes is set to suffer erosion. This is a major concern for Bangladesh and other LDCs in the Asia-Pacific region. This paper attempts to make an estimate about the range of preferential erosion for Bangladesh given her current trade pattern and preferential treatment enjoyed by her exports. The paper finds that for Bangladesh, the preferential erosion could be substantial (e.g. $42.1 million worth of net preference erosion in the EU alone for RMG products under one of the possible scenarios). Reduced preference margin will also undermine future competitiveness in the developed country markets. It is also to be noted that tariff reductions under NAMA will have positive implications for Bangladesh in the US market where most of Bangladesh’s industrial goods do not enjoy GSP treatment. Thus, tariff reduction under NAMA is expected to have diverse implications for Bangladesh’s export of industrial goods. NAMA, thus, may increase Bangladesh’s competitive edge vis-à-vis Caribbean and Sub-Sahara African countries which are currently enjoying zero-tariff access for apparels under the AGOA and the CBI. The paper reviews some of the proposals that are being discussed to address the possible negative consequences of preference erosion for the LDCsWTO-General Council, NAMA, Bangladesh

HEAT TRANSFER AND CHEMICAL PROCESSES IN CHEMICAL VAPOR DEPOSITION REACTOR FOR SYNTHESIS OF CARBON NANOTUBES

A small-scale model of a CVD reactor was built. Axial and radial of major species concentrations and temperature profiles were obtained with a micro gas chromatograph and a fine thermocouple. Those temperature and species concentrations revealed detailed thermal and chemical structures of the CVD reactor. The concentrations of argon plus hydrogen, methane, and C2Hx (C2H2 + C2H4 + C2H6) resulting from xylene decomposition were measured along the CVD at different temperatures. Ferrocene was added to xylene to investigate the effect of a catalyst on composition profiles. The results with ferrocene indicated an increase in CH4 and C2Hx concentrations. At 1000 C and above, the increase of C2Hx concentration is higher than that for CH4. The effect of ferrocene was very minor on the concentration of the gases. Finally composition and temperature profiles were measured and plotted for the radial direction at X=75 cm and T=1200 C. The overall rate constant for the gas-phase reaction was calculated based on the measured species concentration data using the Benson and Shaw reaction mechanism. Our study showed that the Benson and Shaw mechanism could be used in the temperature range lower than 800 C. Also the effect of hydrogen in the syntheses of CNTs, in the CVD reactor using xylene and ferrocene, was studied. Both single-step and two-step methods were applied. In the single-step method, the ferrocene was dissolved in the xylene. In the two step-method the catalyst preparation step was performed first; ferrocene powder was placed in the preheater for a certain period of time and carried by a mixture of argon and hydrogen at fixed concentration to get catalyst nanoparticles deposited on the reactor wall. Xylene then was injected to the reactor. To study the effect of hydrogen, the synthesized materials were observed by SEM and TEM. The results showed that the presence of hydrogen is essential for CNTs to be synthesized by the CVD method, and also the concentration of hydrogen in the reactor has a great effect on the quality of CNTs. The yield of CNTs in the two-step method was slightly higher than that in the one-step method

Trade Potential in SAFTA: An Application of Augmented Gravity Model

The present paper investigates the trade creation and trade diversion effects of a number of RTAs, with special focus on the SAFTA, by using a gravity model. Apart from the traditional gravity variables, the model is augmented by some other import variables (e.g. bilateral exchange rate, bilateral free trade agreement). To capture the individual country effect, along with the impact of overall RTA, a set of additional dummy variable has been introduced. The model developed in this paper is estimated by using panel data approach with country-pair specific as well as year specific fixed effects. Two stages estimation technique is deployed to arrive at the estimates. The first stage is estimated using Tobit Model, while OLS is applied in the second stage. The study finds significant intra-bloc export creation in SAPTA; however, at the same time there is evidence of net export diversion in the SAPTA. Bangladesh, India and Pakistan are expected to gain from joining the RTA, while Nepal, Maldives and Sri Lanka are likely to be negatively affected. Among the other RTAs covered under the present study, AFTA, NAFTA, SADC, MERCOSUR, CAN, EAC are associated with intra-bloc export creation and net export diversion. EU and Bangkok agreement (APTA) are found to be intra-bloc export diverting and net export diverting. BIMSTEC is found to be intra-bloc export diverting but there is no evidence of net export creation or diversion. Although none of the RTAs covered by the study was found to be net export creating, more than one third of the members of these RTAs are found to be positively affected by joining the RTAs.Trade potential, SAFTA, RTA, Gravity Model, Bangladesh, India, Pakisthan, Sri Lanka, Nepal, Maldives

Application of Decline Curve Analysis to Unconventional Reservoir

The oil and gas industry has been dealing with the unconventional reservoirs for about only two decades. Consequently, many challenges remain in evaluating the unconventional reservoirs. A few of these obstacles are the absence of the adequate production history, understanding the fluid flow regime after hydraulic fracturing, and estimating the drainage volume of the reservoir. One of the essential elements for evaluation of the oil and reservoir is to estimate the production rates over time in order to investigate the economic potential of the project. Decline Curve Analysis (DCA) is most common the methodology for predicting the production rates over the time based on past production data. However, conventional DCA methods cannot be applied to unconventional reservoir due to lack of sufficient and consistent past production history. Accordingly, several DCA methods (Arps, PLE, SPED, and Duong) have been proposed to estimate the production over time for unconventional reservoirs. However, their reliability and accuracy remain uncertain. In this problem report, field production data from hydraulically fractured horizontal wells completed in Marcellus Shale will be analyzed using different DCA methods for unconventional reservoirs. Accordingly, this will lead to a better understanding which DCA method can provide accurate predictions of the future production rates from the unconventional reservoirs

NAMA negotiations in the WTO and preference erosion: concerns of Bangladesh and other regional LDCs

The ongoing negotiations on non-agricultural market access (NAMA) in the WTO are expected to lead to substantive reductions in the tariff rates on industrial goods in both the developed and the developing countries. Although an agreement on the formula and coefficient(s) is yet to be reached, it is becoming increasingly clear that countries are moving towards a differentiated swiss-type formula with deeper cuts for higher tariffs. The July (2004) Framework Agreement stipulated that LDCs will not be required to undertake any tariff reduction commitments under the NAMA. However, LDCs are likely to suffer substantive tariff preference erosion as a consequence of NAMA negotiations since any tariff reduction by the developed countries will result in a fall in the preferential margins currently enjoyed by the LDCs under the various GSP schemes operated by the developed countries. Consequently, the competitive edge currently enjoyed by the LDCs by taking advantage of the preferential treatment under the various GSP schemes is set to suffer erosion. This is a major concern for Bangladesh and other LDCs in the Asia-Pacific region. This paper attempts to make an estimate about the range of preferential erosion for Bangladesh given her current trade pattern and preferential treatment enjoyed by her exports. The paper finds that for Bangladesh, the preferential erosion could be substantial (e.g. $42.1 million worth of net preference erosion in the EU alone for RMG products under one of the possible scenarios). Reduced preference margin will also undermine future competitiveness in the developed country markets. It is also to be noted that tariff reductions under NAMA will have positive implications for Bangladesh in the US market where most of Bangladesh’s industrial goods do not enjoy GSP treatment. Thus, tariff reduction under NAMA is expected to have diverse implications for Bangladesh’s export of industrial goods. NAMA, thus, may increase Bangladesh’s competitive edge vis-à-vis Caribbean and Sub-Sahara African countries which are currently enjoying zero-tariff access for apparels under the AGOA and the CBI. The paper reviews some of the proposals that are being discussed to address the possible negative consequences of preference erosion for the LDCs

Die Rolle der HLA Klasse II-Antikörper im Pathomechanismus der transfusionsassoziierten akuten Lungeninsuffizienz

Die transfusionsassoziierte akute Lungeninsuffizienz (TRALI) ist die Haupttodesursache bei Bluttransfusionen in den USA und anderen Nationen. Über 90% aller untersuchten TRALI-Fälle, welche aus Originalarbeiten sowie dem Hämovigilanzregister stammen, zeigen einen Nachweis von HLAAntikörpern im Spenderplasma und das Vorhandensein des korrespondierenden Antigens beim Empfänger. Hierbei handelte es sich in einer Vielzahl der Fälle um Antikörper gegen HLA-Klasse II-Merkmale. Das korrespondierende Antigen tragen aber weder Granulozyten noch Endothelzellen, was eine direkte Aktivierung dieser Zellen ausschließt. Beide Zelltypen können zwar theoretisch im aktivierten Zustand HLA-Klasse IIAntigene exprimieren, aber in vivo gibt es bislang keine Hinweise bzw. Belege hierfür. Ein alternativer Mechanismus über die Aktivierung von Monozyten wurde daher in Erwägung gezogen. In der vorliegenden Arbeit konnten wir anhand von in vitro und ex vivo Untersuchungsmethoden einen indirekten Aktivierungsweg der TRALI über Monozyten nachweisen. Den Monozyten kann dadurch eine zentrale Rolle im Pathomechanismus der HLA Klasse II-induzierten TRALI zugeschrieben werden. Monozyten wurden durch die Inkubation mit korrespondierenden HLA Klasse II Antikörpern aktiviert. In diesem aktiviertem Zustand waren sie fähig, Zytokine freizusetzen, die neutrophile Granulozyten aktivieren, die wiederum zu einer Störung der endothelialen Lungenbarriere führten. In unserem ex vivo Rattenlungenmodell führte die HLA Klasse IIantikörperabhängige Monozytenaktivierung in einer klinisch relevanten Zeit zu einem ausgeprägtem Lungenödem, wenn das Lungenendothel zwei Stunden vor Versuchsbeginn mit LPS voraktiviert wurde und neutrophile Granulozyten anwesend waren. Unsere Daten lassen die Vermutung zu, dass in einer Vielzahl der TRALI-Fälle Monozyten zelluläre Schlüsselfiguren sind und dass HLA Klasse II Antikörper TRALI durch eine Kaskade auslösen, welche durch eine Monozytenaktivierung eingeleitet wird. Desweiteren lassen die Daten den Schluss zu, dass die TRALI-Pathogenese einem Schwellenmodell folgt. Die Ergebnisse dieser Arbeit unterstützen den kürzlich gefassten Entschluss, mehrfach schwangere Frauen von der Plasmaspende auszuschließen.Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated death in the United States and other countries. In about 90% of all TRALI cases, human leucocyte antibodies have been identified in the implicated blood donor and the cognate antigens were found on the recipients’ blood cells. Most of these antibodies are HLA class II antibodies. The corresponding antigens are usually not expressed on neutrophils or endothelial cells. This fact excludes a direct activation of neutrophils by these antibodies. Both types of cells are theoretically able to express HLA class II molecules on their surface in an activated state. However, there are no in vivo data proving this. Of note, it remains unclear how HLA class II-antibodies can induce TRALI. Alternative mechanisms leading to TRALI have been proposed, but the available evidence strongly suggests that donor leucocyte antibodies may initiate a reaction cascade via monocytes. In this study, we identify by in vitro and ex vivo experimental methods, human monocytes as a primary target in HLA class II induced TRALI. Because of these findings, monocytes gain a central role in HLA class II induced of TRALI. Monocytes become activated with matched HLA class II-antibodies and are capable of activating neutrophils which, in turn, lead to a disturbance of the endothelial barrier. In our ex vivo rodant model, HLA class II antibodydependent monocyte activation induced a severe pulmonary edema in a relevant period of time, whenever neutrophils are present and the endothelium was preactivated by LPS. Our experimental data suggest that in most TRALI cases, monocytes are cellular key players, because HLA class II antibodies induce TRALI by a reaction cascade, which starts with an activation of monocytes. Furthermore, our data support the previous assumption that TRALI pathogenesis follows a threshold model. The experimental data of this work support the current decision to avoid plasma from immunized donors, such as women with a history of pregnancy, from future donation

UNDERGRADUATE MATHEMATICS STUDENTS’ ATTITUDES TOWARD USING E-LEARNING IN SAUDI ARABIA

Title from document title page. Document formatted into pages: contains 98 p.:ill. Includes abstract.The main objective of this study was to investigate the attitudes of undergraduate mathematics students in Saudi Arabia towards online mathematics education. Comparisons were made among male, female, underclassmen, and upperclassmen undergraduate mathematics students at the University of Tabuk (UT). Of 161 students enrolled in the mathematics program, 118 mathematics students responded to the survey. The sample consisted of 57 male and 61 female students. A 2 x 2 ANOVA test was used to reveal any statistically significant differences between the various groups based on gender and educational level. The findings showed that underclassmen did not differ significantly from upperclassmen in their attitudes toward online mathematics, male students did not differ significantly from female students in their attitudes toward online mathematics, and there was no significant interaction between educational level and gender in terms of the students’ attitudes toward online mathematics education