bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of drought across central Sudan using UNEP dryness ratio
Authors: Elagib Nadir Ahmed
Published: August 2009

The objective of this paper is to improve our perception of drought in central Sudan. This has been realized by detailing the changes that occurred in the dryness ratio (rainfall/potential evapotranspiration) of the United Nations Environment Programme (UNEP) during the period 1941–2005. Eight representative stations of the area were selected and their dryness ratios examined on annual and monthly bases. A trend towards intensifying and more recurrent drought has been found. This trend is particularly significant in the arid areas. Statistically significant increase in areal coverage of drought has occurred. Substantial changes took place in the severity and frequency of drought between 1941–1970 and 1971–2005 over the whole area. Moreover, the early to mid-1970s, mid-1980s, early 1990s and early 2000s were determined as common drought years and were among the driest 10 years. The analysis also revealed high and generally increasing inter-annual variability of the dryness ratio. There is not a dominant short-term persistence in the data, as assessed by the lag-one serial correlation coefficient. Early forecast of the moisture condition during the rest of the season could merely be accomplished at small scale in the area. These results indicate that drought in the study area is irregular.
A formal statistical model for pooled analysis of extreme floods
Authors: Kjeldsen Thomas R. , Jones David A.
Published: August 2009

This paper describes a formal statistical model underlying the region-of-influence method routinely used in regional frequency analysis of hydrological extremes, and is an improvement to the existing Flood Estimation Handbook (FEH) method for pooled frequency analysis of annual maximum flows in the UK. Specification of a pooling-group method requires three issues to be resolved: how to define hydrological similarity, the size of pooling groups and calculation of the pooled L-moment ratios. Because these issues are interrelated, an exploratory and iterative study has been undertaken before arriving at the final version of the method. Improvements provided by the model are: (1) that it allows an increased weight to be given to a gauged catchment when it is itself the target location and (2) it does not require identification of a homogeneous region, since the expected differences between the L-moment ratios within a pooling group are explicitly accounted for. Using annual maximum series from 602 gauged rural catchments, a comparison of candidate methods shows that the new method performs better than these others, including the FEH method. While the numerical comparison suggests that the improvement is 4%, and thus only minor, arguments are given for why this is a misleading conclusion.
Model-based pH monitor for sensor assessment
Authors: van Schagen Kim , Rietveld Luuk , Veersma Alex , Babuška Robert
Published: August 2009

Owing to the nature of the treatment processes, monitoring the processes based on individual online measurements is difficult or even impossible. However, the measurements (online and laboratory) can be combined with a priori process knowledge, using mathematical models, to objectively monitor the treatment processes and measurement devices. The pH measurement is a commonly used measurement at different stages in the drinking water treatment plant, although it is a unreliable instrument, requiring significant maintenance. It is shown that, using a grey-box model, it is possible to assess the measurement devices effectively, even if detailed information of the specific processes is unknown.
EDTA and electricity synergetic catalyzed Fe3 + /H2O2 process for amoxicillin oxidation
Authors: Shen Ting-Ting , Li Xiao-Ming , Tang Yu-Fang , Wang Juan , Yue Xiu , Cao Jian-Bin , Zheng Wei , Wang Dong-Bo , Zeng Guang-Ming
Published: August 2009

Three oxidation processes for amoxicillin wastewater pretreatment such as Electro-Fe3 + (EDTA)/H2O2 (EDTA: ethylenediaminetetraacetic acid), Fe3 + (EDTA)/H2O2 and Electro-Fe3 + /H2O2 were simultaneously discussed at pH of 7.0 (±0.1). It was found that the above processes could achieve 78%, 64%, 33% chemical oxygen demand (CODcr) removal, and 86%, 70%, 47% amoxicillin degradation respectively. Moreover, the results of biodegradability (biological oxygen demand (BOD5)/CODcr ratio) showed that the Electro-Fe3 + (EDTA)/H2O2 process was a promising way to pretreat antibiotic wastewater due to the biodegradability of the effluent improved to 0.48 compared with the cases of Fe3 + (EDTA)/H2O2 (0.40) and Electro-Fe3 + /H2O2 process (0.12). Therefore, it was reasonable to note that EDTA and electricity showed synergetic effect on the oxidation process. Additionally, infrared spectra (IR) were applied to concisely propose a potential degradation way of amoxicillin. The characteristic changes of H2O2 and EDTA in the oxidation process were also investigated in detail.
Consequences to water suppliers of collecting rainwater on housing estates
Authors: Gires Auguste , de Gouvello Bernard
Published: August 2009

The collection, storage and use of rainwater from roofs reduce the need for potable water. However, if water suppliers are to decrease their infrastructure costs as well as their operational costs (due to water savings), the rainwater system has to provide most of the time a significant percentage of the water demand. This paper adopts the viewpoint of the water suppliers and investigates how reliable this source of water is in the case of a housing estate, considering WC flushing as the only water demand. A housing estate was modelled and different realistic input scenarios (water demand for WC flushing, storage capacity, roof area, and rainfall) were defined. Three indicators were exhibited. The variability generated by each input on the indicators was evaluated. The indicators were estimated for 63 homogeneously distributed French cities. Among the indicators exhibited in this paper, the most relevant one is the percentage of water supplied from the tank that is secured during 95% of the days of the simulation. The main conclusion is that the optimum way of determining the storage capacity of the rainwater collection system is not the same from the viewpoint of the users than from the viewpoint of the water suppliers. Indeed, water suppliers tend to require bigger tanks in order to take into account the rainwater collection systems in their management plan.
Application of combined membrane biological reactor and electro-oxidation processes for the treatment of landfill leachates
Authors: Aloui Fathi , Fki Firas , Loukil Slim , Sayadi Sami
Published: August 2009

Landfill leachate (LFL) is a very complex wastewater that poses considerable hazards to local communities and the environment. With this concern in mind, the present study was undertaken to investigate the performance of an aerobic membrane bioreactor treating raw LFL from Djebel Chekir (Tunisia) discharge. The LFL samples collected from this site were found to be highly loaded with organic matter, ammonia, salts, greases, phenols and hydrocarbons. Important removals of chemical oxygen demand (COD) and NH4+-N were attained after 44 days of treatment at optimum conditions for the membrane and with organic loading rates (OLR) of 1.9 and 2.7 grams COD per litter and day. This treatment allowed for an important detoxification of the landfill leachates and a significant elimination of the microorganisms. Electrochemical oxidation using Pi/Ti was applied as a post-treatment and after the biological process in order to reduce the residual ammonia and COD. At a pH value of 9, current density of 4 A dm−2 and electrolysis time of 60 minutes, COD and ammonia nitrogen were reduced to 1,000 mg L−1 and 27 mg L−1, respectively. COD and NH4+-N removals were accompanied by significant detoxification.
Selection of variables for on-line monitoring, diagnosis, and control of anaerobic digestion processes
Authors: Molina F. , Castellano M. , García C. , Roca E. , Lema J. M.
Published: August 2009

This work aims to systematize the study of indicators for two types of wastewaters: carbohydrate-based and protein-based synthetic wastewaters. Characterization of steady states and dynamic response analysis against disturbances were carried out using both a factorial discriminant analysis (FDA) and a phenomenological analysis, respectively. This research seeks reconciling both sets of indicators in order to optimize resources and provide a minimal cost in instrumentation for its implementation at industrial scale. According to the results of this research, the best indicators for the two types of wastewaters, considering both process steady states and organic load perturbations are: Biogas flow rate or Methane flow rate, and Hydrogen concentration in the biogas; Volatile fatty acids and Partial alkalinity in the liquid phase.
Cellular nicotinamide adenine dinucleotide (NADH) as an indicator of bacterial metabolic activity dynamics in activated sludge
Authors: Wos M. L. , Pollard P. C.
Published: August 2009

In this study, native fluorescent nicotinamide adenine dinucleotide (NADH) was used as a direct indicator of bacterial metabolic activity in activated sludge. Specific NADH concentration was dynamic and varied between 106–108 molecules per bacterial cell. Low concentrations (106–107 NADH molecules cell−1) indicate efficient bacterial metabolic activity while high concentrations (107–108 NADH molecules cell−1) indicate inefficient bacterial metabolic activity. Specific [NADH] did not correlate to changes in dissolved organic carbon, but increases correlated to decreases in oxygen uptake rates. Perhaps a lack of oxygen as the terminal electron acceptor prevented efficient reoxidization of NADH to NAD+, which resulted in an accumulation of NADH within the cells. Also, significant amounts of NADH were released and accumulated into the extracellular medium of metabolically active E. coli cells in log phase. Such overflow metabolism may be the product of favourable conditions. Thus, the flux of both specific intracellular and extracellular [NADH] indicates the dynamics of bacterial metabolic activity in activated sludge.
Quantification of sewer system infiltration using δ18O hydrograph separation
Authors: Prigiobbe V. , Giulianelli M.
Published: August 2009

The infiltration of parasitical water into two sewer systems in Rome (Italy) was quantified during a dry weather period. Infiltration was estimated using the hydrograph separation method with two water components and δ18O as a conservative tracer. The two water components were groundwater, the possible source of parasitical water within the sewer, and drinking water discharged into the sewer system. This method was applied at an urban catchment scale in order to test the effective water-tightness of two different sewer networks. The sampling strategy was based on an uncertainty analysis and the errors have been propagated using Monte Carlo random sampling. Our field applications showed that the method can be applied easily and quickly, but the error in the estimated infiltration rate can be up to 20%. The estimated infiltration into the recent sewer in Torraccia is 14% and can be considered negligible given the precision of the method, while the old sewer in Infernetto has an estimated infiltration of 50%.
Removal of organics from different types of landfill leachate by ozonation
Authors: Žgajnar Gotvajn A. , Derco J. , Tišler T. , Cotman M. , Zagorc-Končan J.
Published: August 2009

The objective of this investigation was determination of feasibility of ozonation for treatment of leachates from municipal landfill. Efficiency of ozonation was determined for two leachates, different in age, composition and toxicity. We have studied the impact of ozonation time on removal of organics. The efficiency of treatment was monitored by COD, BOD5 and DOC analyses, removal of nitrogen compounds, as well as changes in toxicity. Therefore, acute toxicity tests with luminiscent bacteria Vibrio fischeri, Daphnia magna and nitrifying organisms of activated sludge (ammonium oxidation) were performed prior and after ozonation experiments. It has been confirmed that longer time of ozonation does not bring significantly better results regarding treatment of young leachate (36% in 20 minutes, 42% in 120 minutes). Two steps kinetics observed resulted in minor detoxification regarding luminiscent bacteria and no changes in effects to daphnids. More effective was ozonation of the stabilized leachate. Removal of COD reached 50% in 80 minutes and 65% in 120 minutes. Detoxification was also observed. Presented research confirmed, that ozonation itself was not effective treatment methods for investigated types of leachates for reduction of their hazardous impacts to meet regulatory effluent limits.
Pilot study on control of phytoplankton by zooplankton coupling with filter-feeding fish in surface water
Authors: Ma Hua , Cui Fuyi , Liu Zhiquan , Fan Zhenqiang
Published: August 2009

A pilot-scale facility was originally designed to control phytoplankton in algae-laden reservoir water characterized by summer cyanobacteria blooms (mainly Microcystis flos-aquae). The system made good use of the different food habits of Daphnia magna and silver carp. Zooplankton (Daphnia magna), filter-feeding fish (silver carp), and zooplankton (Daphnia magna) were stocked in three separated tanks in sequence, respectively. Thus, single-cell phytoplankton and some Microcystis flos-aquae in small size were first grazed by Daphnia magna in the first tank, and in the second tank phytoplankton larger than 10 μm were filtered by silver carp, and the concentration of the remaining phytoplankton was further reduced to a rather low level by Daphnia magna in the third tank. The results showed that the system had good removal efficiencies of phytoplankton and chlorophyll a, 86.85% and 59.41%, respectively, and permanganate consumption (CODMn) and turbidity were lowered as well. A high phytoplankton removal efficiency and low cost indicated that the system had a good advantage in pre-treating algae-laden source water in drinking water works.
A case study: bulk organic matters and nitrogen removal from reclaimed water by enhanced direct injection-well groundwater recharge system
Authors: Xuan Zhao , Xuzhou Cheng , Meng Zhang
Published: August 2009

A new kind of artificial groundwater recharge approach named enhanced direct injection-well recharge (EnDir), consisting of short-term artifical vadose treatment and long-term aquifer treatment, is put forward and demonstrated in Beijing. The results reveal that granular activated carbon (GAC) could remove bulk organic matters with the DOC value decrease from 6.0 mg/L to 4.6 mg/L. The short-term vadose treatment of EnDir exhibited additional organic carbon removal and effective nitrification. DOC and AOX values were reduced to 4.1 mg/L and 56.8μg/L respectively. Ammonia-N of 3.81 mg/L was converted into equivalent nitrate-N. The long-term aquifer treatment offers favorable denitrification and lower nitrate-N content in the aquifer. The bulk parameters of DOC, SUVA, AOX and ammonia-N detected in the monitoring wells are as the same level as that of local groundwater. Brief financial analysis demonstrated the promising economic aspects of EnDir system in Beijing.
Water resource use and management by the United States forest products industry
Authors: Wiegand P. S. , Flinders C. A. , Ice G. G. , Malmberg B. J. , Fisher R. P.
Published: August 2009

The connections between forest products operations and water resources in the United States is considered and, where possible, quantified. Manufacture of wood, pulp, and paper products and the influences of forest management and forest products manufacture on water quality are discussed. Most fresh water in the US originates in forested areas. Responsible harvesting strategies, best management practices, and forest re-growth combine to minimize or eliminate changes in water availability and degradation of water quality due to harvesting. Relative to alternative land uses and large-scale disturbance events, forested areas produce the highest quality of fresh water. Water inputs for the manufacture of forest products total about 5.8 billion m3 per year, an amount equal about 0.4% of the surface and groundwater yield from timberland. Approximately 88% of water used in manufacturing is treated and returned directly to surface waters, about 11% is converted to water vapor and released during the manufacturing process, and 1% is imparted to products or solid residuals. Extensive study and continued monitoring of treated effluents suggest few or no concerns regarding the compatibility of current effluents with healthy aquatic systems.
State Policy Climates for College Student Success: An Analysis of State Policy Documents Pertaining to College Persistence and Completion
Authors: McLendon Michael K. , Tuchmayer Jeremy B. , Park Toby J
Published: August 2009

This article reports the findings of an exploratory analysis of state policy climates for college student persistence and completion. We performed an analysis of more than 100 documents collected from 8 states chosen largely on the basis of their performance on past Measuring Up reports. Our analysis of governors' state-of-the-state addresses, state Master Plans, and performance-funding programs produced several notable findings. Although we had assumed that states that perform better in retaining and graduating their college students would likely have state policy climates that espouse greater support for college student success, our analysis provided some evidence that it is the lower-performing states, in fact, whose policy climates espouse more support for these goals. We also found evidence of rising political support across all states for increased college persistence and completion, although the rate of growth of support has risen fastest over the past 8 years in low-performing states. We examine some of the implications of these findings, and present several directions that future research might take in studying state policy climates for college student success.
College Persistence among Undocumented Students at a Selective Public University: A Quantitative Case Study Analysis
Authors: Flores Stella M. , Horn Catherine L.
Published: August 2009

Texas House Bill 1403, which was passed in 2001, is the first in-state resident tuition (ISRT) policy to benefit undocumented students in the United States. Seven years later, the literature includes virtually no empirical evidence of the persistence patterns of students who have enrolled in postsecondary institutions as beneficiaries of the in-state resident tuition policies in Texas, and in the United States in general. This study represents one of the first research studies to provide a quantitative analysis of the persistence behavior of ISRT policy eligible students at a large selective public institution in Texas. The findings, while not generalizable to all postsecondary institutions with this population, provocatively suggest that ISRT recipients are remaining in college at rates similar to those of their Latino peers who are U.S. citizens and legal residents. The study addresses the implications of this policy for selective institutions and makes suggestions for further research.
The Study of Institutional Practices Related to Student Persistence
Authors: Ziskin Mary , Hossler Don , Kim Sooyeon
Published: August 2009

Using literature and illustrations drawn from a pilot study, this article explores the theoretical and methodological challenges entailed in the study of student retention. We center the discussion around two important efforts to expand the theoretical base and scope for research in this area: Berger's (2000) concept of colleges and universities as optimizers of cultural capital and Bensimon's (2007) recent critique of the narrowness of the frames that predominate student retention research. By way of exploring these issues through a concrete example, the article presents an overview of processes and findings from a funded pilot study of institutional policies and practices surrounding student retention. This exploration—part essay, part research report—leads us ultimately to pose two central questions on which, we suggest, future research should build: What are institutions doing to improve student retention? and How do institutions intervene in the workings of cultural capital in higher education?
Innovation in the Indian Semiconductor Industry: The Challenge of Sectoral Deepening
Authors: Keller William W. , Pauly Louis W.
Published: August 2009

Seeking to build on related successes in other information technology sectors, the government of India has signaled its intent to transform the country's performance in microelectronics. Facing a young and expanding population, India needs to create manufacturing jobs in promising industries, and it needs to build out from its limited high-technology base. Semiconductors are foundational in this regard. Today, there is much discussion within India about the link between semiconductors and innovation in bio-electronics, alternative energy production and storage, and various micro- and nano-devices. The government's contemporary attempt to promote the building of infrastructure for manufacturing and applied research in semiconductors highlights reasons for hope. So too does the remarkable talent now available in the Indian diaspora. But significant impediments, especially in postsecondary and graduate-level education, must still be overcome if the necessary human capital is to be developed, equipped, and deployed effectively.
On the effect of chemical reaction, heat and mass transfer on nonlinear MHD boundary layer past a porous shrinking sheet with suction
Authors: Muhaimin I. , Kandasamy Ramasamy , Hashim I. , Khamis Azme
Published: August 2009

This work is concerned with magnetohydrodynamic viscous flow due to a shrinking sheet in the presence of suction. The cases of two dimensional and axisymmetric shrinking are discussed. The governing boundary layer equations are written into a dimensionless form by similarity transformations. The transformed coupled nonlinear ordinary differential equations are numercally solved by using an advanced numeric technique. Favorability comparisons with previously published work are presented. numerical results for the dimensionless velocity, temperature and concentration profiles are obtained and displayed graphically for pertinent parameters to show interesting aspects of the solution.
Universal equations of unsteady two-dimensional MHD boundary layer whose temperature varies with time
Authors: Boricic Zoran , Nikodijevic Dragisa , Obrovic Branko , Stamenkovic Zivojin
Published: August 2009

This paper concerns with unsteady two-dimensional temperature laminar magnetohydrodynamic (MHD) boundary layer of incompressible fluid. It is assumed that induction of outer magnetic field is function of longitudinal coordinate with force lines perpendicular to the body surface on which boundary layer forms. Outer electric filed is neglected and magnetic Reynolds number is significantly lower then one i.e. considered problem is in inductionless approximation. Characteristic properties of fluid are constant because velocity of flow is much lower than speed of light and temperature difference is small enough (under 50?C ). Introduced assumptions simplify considered problem in sake of mathematical solving, but adopted physical model is interesting from practical point of view, because its relation with large number of technically significant MHD flows. Obtained partial differential equations can be solved with modern numerical methods for every particular problem. Conclusions based on these solutions are related only with specific temperature MHD boundary layer problem. In this paper, quite different approach is used. First new variables are introduced and then sets of similarity parameters which transform equations on the form which don't contain inside and in corresponding boundary conditions characteristics of particular problems and in that sense equations are considered as universal. Obtained universal equations in appropriate approximation can be solved numerically once for all. So-called universal solutions of equations can be used to carry out general conclusions about temperature MHD boundary layer and for calculation of arbitrary particular problems. To calculate any particular problem it is necessary also to solve corresponding momentum integral equation.
School effectiveness: Literature review
Authors: Teodorovic Jelena
Published: August 2009

In this paper, the reader embarks on the first part of the review of school effectiveness research. The aim of the review is to offer a clearer picture on whether, which, and how much teacher and school variables impact student achievement, as there is currently no wider and accepted consensus on this matter, in spite of the wealth of various school effectiveness studies. An introduction is followed by a section on fragmented research paradigms. Four subsequent sections describe and critique findings from these paradigms, namely from student background, input-output, effective-schools, and instructional effectiveness studies. The paper concludes with the section on synthesis of findings, which implicate student background variables as the most important for student achievement, followed by instruction and teacher-related variables (in very poor developing countries, input-output factors are also relevant for student success). Subsequent paper will showcase more recent school effectiveness studies that use appropriate methodology and conceptual framework for identification of the most important school effectiveness factors.
Learning approaches and studies of effect of environmental factors
Authors: Mirkov Snezana
Published: August 2009

There is a presentation of 3P model of learning (Presage-Process-Product), which comprises learning approaches placed in a wider context of the set of variables related to personality, environment, process and outcomes of learning. Three approaches to learning - surface, deep and achievement-oriented - consist of motives and the corresponding learning strategies. There is a discussion of the findings and implications of a great deal of research using the instruments based on this model. We analyzed research findings about the effect of instruction on learning approaches acquired by pupils, and especially students. It is shown how based on learning approach employed by pupils it is possible to draw conclusions about the quality of instruction. Testing the instruments on various samples indicates that the model is applicable in different cultures. Cross-cultural research opened up the problem of relation between memorising and understanding. Further research is necessary, both empirical and theoretical, that is, development of conceptualization of these constructs, and especially their role in education. Perspectives for further research also open up in the direction of studying various factors connected with personality and their relations with learning approaches. The role of learning approaches of teachers in developing the learning approaches of pupils is yet to be examined.
Content of teachers' stereotypes about adolescents
Authors: Djeric Ivana
Published: August 2009

Discourse on 'problematic behavior' of the young in adolescence period is often present in lay, media, professional and scientific public. In this research, we performed empirical testing of the psychological concept of 'storm and stress', which is manifested by stereotypes about adolescents as rebels. The goal was to establish whether teachers hold stereotypes about younger adolescents as a social group and what the content of the stereotype is. Research participants were 193 teachers teaching the seventh grade in ten Belgrade primary schools. Factor analysis method established the presence of several factors, which reflect the psychological content and meaning of teachers' stereotypes about younger adolescents. The results of our research point out: (a) that stereotypes of teachers about younger adolescents stand in partial correspondence with the content of a widely distributed concept of 'storm and stress'; (b) that this concept is mostly loaded with a negative perception of pupils on the part of teachers and (c) that teachers less often perceive pupils through the prism of some positive qualities. That is, teachers think that these positive qualities are not 'typical' qualities of adolescents if they are observed as a group. Interviewed teachers hold stereotypes about younger adolescents, but intensity and valence of stereotypes vary depending on the nature of obtained factors.
Maps and virtual geo-presentations in contemporary instruction
Authors: Vemic Mirceta
Published: August 2009

This paper analyses the basic questions regarding cartographic visualization in instruction, where traditional maps, atlases and globes were considered only as simple visual aids belonging together with original objects and pictures, while cartographers elevated them to a higher cognitive level, labelling them 'eye of geography', 'sediment of the entire knowledge', 'philosopher's stone', or the very 'foundation' of geography. Maps were always required to be correct, comprehensive, clear, understandable, legible, to have nice appearance and format, which suggests the 'invariability' of maps, although the technique and technology change. Contemporary computer technology changed the cartographic picture in the form of virtual geo-presentations and geographic information systems. Through mutual comparison with traditional maps it is easier to discern all the aspects of their application in contemporary instruction. This paper particularly analyses epistemological, semiotic, methodological and didactic-methodical aspects of maps and virtual geo-presentations, with the emphasis on their perceptive possibilities. By introducing the teacher with the aforementioned aspects, they are demystified, didactic process is elevated and a wider application in contemporary instruction opens up, either with respect to content presentation or application of direct mapping through exercises, workshops, seminar or graduation papers. Knowledge adopted in this way influences creation of a higher level of creative thinking, that is, visual thinking.
On the Use of Factor-Analytic Multinomial Logit Item Response Models to Account for Individual Differences in Response Style
Authors: Johnson Timothy R. , Bolt Daniel M.
Published: August 2009

Multidimensional item response models are usually implemented to model the relationship between item responses and two or more traits of interest. We show how multidimensional multinomial logit item response models can also be used to account for individual differences in response style. This is done by specifying a factor-analytic model for latent responses at the category level. This permits traits and response style to be separated into separate but possibly correlated factors when properly identified by the factor structure. Special cases of this model can be viewed as generalizations of some unidimensional multinomial logit item response models. In this article, we describe and demonstrate the specification and implementation of these models to account for individual differences in response style that would otherwise compromise the validity of the measurement model.
Quantitative 3D characterisation of graphite morphology in cast iron – correlation between processing, microstructure and properties
Authors: Velichko Alexandra , Mücklich Frank
Published: August 2009

Cast irons with different graphite morphologies were thoroughly analysed and their influence on the electrical properties was studied. Graphite morphology was analysed with focused ion beam tomography. The graphite crystal structure, nucleation and growth mechanisms were studied using chemical analysis and thin foils observations with transmission electron microscopy. Quantitative three-dimensional characterisation of the shape and spatial connectivity, as well as the growth mechanisms provided understanding of the structure of the different graphite morphologies and allowed the estimation of their influence on the effective properties using simulations directly on the tomographic data. First correlations between manufacturing parameters, spatial microstructure and effective properties were suggested for advanced material development and non-destructive quality control.
Structure, stresses and stress relaxation of TiN/Cu multilayer and nanocomposite coatings
Authors: Köstenbauer Harald , Hofer Anna M. , Fontalvo Gerardo A. , Keckes Jozef , Mitterer Christian
Published: August 2009

Structural evolution, residual stresses, and stress relaxation at elevated temperatures were investigated for sputtered TiN/Cu multilayer films with a bilayer thickness between 100 and 800 nm, as well as nanocomposite films with a Cu content up to 30 at.%, to illuminate the effect of adding a soft metal to a hard nitride. In the nanocomposites the Cu domain size increases with rising Cu content from 7 to 22 nm at the expense of the TiN grain size, while it is strongly related to the bilayer thickness in the multilayers at constant TiN domain size. Films were thermally cycled in vacuum from room temperature up to 650 °C. Stresses during heating are governed by thermo-elastic behaviour and at temperatures above 300 °C by plastic deformation of the Cu phase and stress relaxation of both Cu and TiN, whereas the cooling phase is determined by thermo-elasticity, plastic deformation of the Cu phase and eventually tensile crack formation.
Surface modifications and their effect on the nickel release rate in nickel–titanium shape memory alloys
Authors: Heßing Christian , Pohl Michael
Published: August 2009

Several means of modifying surfaces of nickel – titanium have been investigated to gather information on how topography and the nickel release rates can be influenced. Electrolytically etched nickel – titanium surfaces show a very fine structure but show the highest nickel release of all modified surfaces. Electropolishing reduces the initial roughness of the material and lowers the Ni release due to very thick oxide films emerging in the course of the process of electropolishing. Further enhancement of the oxide layer can be achieved by oxidation in dry air or in a selectively oxidising atmosphere. Selectively oxidised samples exhibit the smallest Ni release of all modified surfaces.
Technology and mechanical properties of advanced γ-TiAl based alloys
Authors: Wallgram Wilfried , Schmölzer Thomas , Cha Limei , Das Gopal , Güther Volker , Clemens Helmut
Published: August 2009

The present paper summarizes our progress in establishing a novel production technology for -TiAl components to be used in advanced aircraft engines. In the beginning the main emphasis is put on the design of a -TiAl based alloy which exhibits excellent hot-workability. Then, the development of a “near conventional” hot-die forging route for this type of intermetallic material is described. Finally, the effect of two-step heat-treatments on the microstructure and the mechanical properties is discussed. Because of the small “deformation window” hot-working of -TiAl alloys is a complex and difficult task and, therefore, isothermal forming processes are favoured. In order to increase the deformation window a novel Nb and Mo containing -TiAl based alloy (TNMTM alloy) was developed, which solidifies via the β-phase and exhibits an adjustable β/B2-phase volume fraction. Due to high volume fractions of -phase at elevated temperatures the alloy can be hot-die forged under near conventional conditions, which means that conventional forging equipment with minor and inexpensive modifications can be used. Examples for the fabrication of -TiAl components employing a near conventional forging route are given. With subsequent heat-treatments balanced mechanical properties can be achieved. The results of tensile and creep tests conducted on forged and subsequently heat-treated TNMTM material are presented.
Influence of an apparent r-curve on strength and fracture statistics of ceramic laminates
Authors: Lube Tanja , Pascual Javier , Danzer Robert
Published: August 2009

Laminates with strong interfaces and having compressive residual stresses in the outer layer are designed to have high strength and high reliability. Bending strength tests on such laminate specimens were performed and compared with tests made on monolithic specimens made from the outer layer material. In both types of specimens fracture started from similar flaws, but the laminate specimens showed a higher strength and Weibull modulus. In the case of the monolithic material the toughness is constant but in the case of the laminates it increases – due to the action of the residual stresses – with crack extension (i. e. it is an apparent toughness).

The influence of the apparent toughness curve on the fracture statistics is discussed. It is also shown that the statistics of the laminate can be determined using the statistics of the monolithic material, if the influence of the residual stresses on the toughness and strength is properly taken into account.
Avoiding grain defects in single crystal components by application of a heat conductor technique
Authors: Ma Dexin , Bührig-Polaczek Andreas
Published: August 2009

During single crystal solidification in turbine blades, grain defects are often formed in the platform region with abrupt variation in cross-section. In order to reduce grain defects arising from component geometries an HC (Heat Conductor) technique was developed. In the production process for ceramic shell moulds, a graphite heat conductor of excellent heat conductivity is inserted close to the inner corner of the platform. This effectively extracts local heat from this critical region during directional solidification. Numerical simulations show that by using HC the thermal condition in the platform region can be significantly improved. The single crystal growth in the blade body can spread into the platform more quickly before the melt at the platform extremity becomes deeply undercooled. Structural investigations reveal a remarkable reduction in grain defect formation, providing confirmation of the effectiveness of the HC technique in improving the casting quality of single crystal components.
Role of corticosteroid Injections versus Physiotherapy for the Treatment of Painful Stiff Shoulder: A Randomised Control Trial
Authors: Nahar Shamsun , Islam Monirul , Hakim M Aliha , Ullah AKM Anwar
Published: August 2009

Study Question: among local corticosteroid injections and physiotherapy, which is the more effective treatment for painful stiff shoulder? Objective: To compare the effectiveness of corticosteroid injections with physiotherapy for the treatment of painful stiff shoulder. Design: Randomised trial. Setting: Physical Medicine Outpatient Department (OPD) of BSMMU and NITOR Subjects: Total 119 patients reported to the Outpatient Department (OPD) of NITOR and BSMMU with pain and stiffness in shoulder were enrolled in the trial. Interventions: Patients were randomly allocated to 6 weeks of treatment either with corticosteroid injections (62) or physiotherapy (57). Main outcome measures: Outcome assessments were carried out 3, 7, 13, 26, and 52 weeks after randomisation; some of the assessments were done by an observer blind to treatment allocation. Primary outcome measures were the success of treatment as measured by scores on scales measuring improvement in the main complaint and pain, and improvement in scores on a scale measuring shoulder disability. Results: At 7 weeks 47 (76%) out of 62 patients treated with injections were considered to be treatment successes compared with 26 (45%) out of 57 treated with physiotherapy (difference between groups were 31%, 95% confidence interval 14% to 48%). The difference in improvement favoured those treated with corticosteroids in nearly all outcome measures; these differences were statistically significant. At 26 and 52 weeks differences between the groups were comparatively small. Adverse reactions were generally mild. Conclusions: The beneficial effects of corticosteroid injections administered by the physicians for treatment of painful stiff shoulder are superior to those of physiotherapy. The differences between the intervention groups were mainly the result of the comparatively faster relief of symptoms that occurred in patients treated with injections. Adverse reactions of injections were generally mild. DOI: http://dx.doi.org/10.3329/bjn.v24i1.3034 Bangladesh Journal of Neuroscience 2008; Vol. 24 (1) : 1-8
Initial Neurologic Symptoms Among Bangladeshi Multiple Sclerosis Patients
Authors: Miah Md Bahadur Ali , Sheikh Abdul Kader , Khan Akhlaque Hosain , Islam Md Rafiqul , Ullah AKM Anwar , Mohammad Quazi Deen
Published: August 2009

This study was undertaken in the Department of Neurology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, from January 2002 to December 2003. The objective of this study was to determine the initial neurologic symptoms of multiple sclerosis among Bangladeshi patients. A total of 25 respondents of multiple sclerosis patients as cases selected by McDonald et al. (2001) diagnostic criteria for multiple sclerosis were enlisted during the study period. The clinical details, investigations of the respondents were reviewed. Data were recorded in predesigned data collection sheet. Out of 25 cases, male patients were 12 (48%) and females were 13 (52%), ratio being 1:1.08. Majority of the patients presented at second, third and fourth decades of life. Most of the patients (56%) had acute onset, followed by subacute (28%) and insidious (16%). Certain clinical characteristics among Bangladeshi multiple sclerosis patients are noteworthy, namely, number of male and female patients almost equal (48% vs 52%), a higher rate of impaired vision (optic nerve involvement, 64%), motor weakness (92%), sphincteric disturbances (92%) and a lower rate of brainstem and cerebellar involvement. Painful tonic spasm was a prominent feature among Bangladeshi patients with multiple sclerosis (8 out of 25, 32%). Out of 25 patients, one (4%) expired due to aspiration pneumonia. Twenty four (96%) survived. Among them 9 (36%) has restricted activity, 7 (28%) were bedridden, 5 (20%) were chairbound, 2 (8%) had minor disability and were in work and 1 (4%) was completely normal. DOI: http://dx.doi.org/10.3329/bjn.v24i1.3035 Bangladesh Journal of Neuroscience 2008; Vol. 24 (1) :9-16
Dyslipidaemia in Cortical Versus Subcortical Infarction
Authors: Sarker Tarun Kanti , Kuddus Md Ruhul , Khan Md Rezaul Karim , Ullah AKM Anwar , Islam Md Rafiqul , Haque Anisul
Published: August 2009

Objectives: The aim of the study was to predict risk of cerebral infarction either cortical or lacunar in population having dyslipidaemia and to create awareness regarding it as a risk factor for ischaemic stroke and to take preventive measures for the prevention of a first or recurrent ischaemic stroke. Method: This study was conducted in the Department of Nurology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka from March to October, 2006. This study included 30 acute ischaemic stroke patients diagnosed by history, clinical findings and confirmed by CT/MRI scan of head within 2 weeks of attack. Both man and woman age ranging from 40-90 years were eligible to enter into the study. The same number of age and sex matched nonstroke patients who gave blood for analysis were included as control. Result: In this study among other risk factors total serum cholesterol was raised in both cortical and lacunar infarct in 50% of cases in comparison to 33.3% controls (P<0.05). LDL-cholesterol levels were raised in both cortical and lacunar infarct in 50% of cases compared to 30% controls (P<0.05). HDL-cholesterol levels were significantly low in cases (70%) compared to control subjects (26.7%). It was significantly low in cases of cortical infarct (77.3%) compared to 50% cases of lacunar infarct (P<0.01). Serum triglyceride levels were raised in 60% of case group and 26.7% of control subjects (P<0.01). Serum triglyceride levels were raised in 54.5% cases of cortical infarcts compared to 75% cases of lacunar infarcts. Conclusion: The results indicate an association between dyslipidaemia and the risk of ischaemic stroke, specially cortical type. Dyslipidaemia more related to cortical infarct than subcortical infarct. Low level of HDL-cholesterol was related to cortical infarct but not with subcortical infarct. DOI: http://dx.doi.org/10.3329/bjn.v24i1.3037 Bangladesh Journal of Neuroscience 2008; Vol. 24 (1) : 24-33
Smoking and Ischemic Stroke
Authors: Uddin Md Jalal , Mondol Badrul Alam , Ahmed Shahrukh , Ullah AKM Anwar , Jabbar MA , Mohammad Quazi Deen
Published: August 2009

This case control observational study was conducted in Neurology Department of Dhaka Medical College Hospital (DMCH) to determine the relation of smoking with ischemic stroke. Fifty cases & 50 controls were selected following certain inclusion & exclusion criteria. The results of the study showed that mean age of ischemic stroke was 63.58 ± 10.22 years. Ischemic stroke was more common in male (M:F=2.57:1). Majority of the ischemic stroke came from middle class economic condition. Habit of smoking was equally present in case & control groups (54% & 52%) respectively. However duration of smoking was significantly longer (P< 0.01) in ischemic stroke patients (35.26 ± 9.97 yrs.) than the control group (24.12 ± 7.32 yrs.). The number of cigarette sticks taken per day was 15 ± 1.2 in stroke patients and 6 ± 1.5 per day in the control group with a significant difference between them (P< 0.01). Longer duration & increased number of cigarette sticks smoking were significantly associated with ischemic stroke (P< 0.01 & P< 0.01). DOI: http://dx.doi.org/10.3329/bjn.v24i1.3041 Bangladesh Journal of Neuroscience 2008; Vol. 24 (1) : 50-54
Obstetric anesthesia: Spinal Sub-arachnoid Blockade
Authors: Ahmad Nezamuddin
Published: August 2009

doi: 10.3329/bjog.v23i1.3048Bangladesh J Obstet Gynaecol, 2008; Vol. 23(1) : 1-2
Society News: Vol.23(1)
Authors: Begum Firoza
Published: August 2009

doi: 10.3329/bjog.v23i1.3058   Bangladesh J Obstet Gynaecol, 2008; Vol. 23(1) : 40-41
Discordance Between Self-report of Physician Diagnosis and Administrative Database Diagnosis of Arthritis and Its Predictors
Authors: SINGH JASVINDER A.
Published: August 2009

Objective.

To study predictors of discordance between self-reported physician diagnosis and administrative database diagnosis of arthritis.

Methods.

A cohort of all veterans who utilized Veterans Integrated Service Network (VISN)-13 medical facilities were mailed a questionnaire that included patient self-report of physician diagnosis of arthritis and questions regarding demographics, functional limitation, and SF-36V (a validated version of the Medical Outcomes Study Short-Form 36). Kappa coefficient was used to assess the extent of agreement between self-report of physician diagnosis and administrative database definitions that incorporated International Classification of Diseases (ICD) codes and use of medications for arthritis. We identified predictors of overall discordance between self-report and administrative database diagnosis using multivariable logistic regression analyses.

Results.

Among 70,334 eligible veterans surveyed, 19,749 subjects had an ICD diagnosis of arthritis in the administrative database in the year prior to the survey; 34,440 answered the arthritis question and 18,464 self-reported a physician diagnosis of arthritis. Kappa coefficient showed slight to fair agreement of 0.19–0.32 between self-report and administrative database definitions of arthritis. We found significantly higher overall discordance among veterans with more comorbidities, greater age, worse functional status, lower use of outpatient and inpatient services, lower education level, and among single medical-site users.

Conclusion.

Low level of agreement between self-report and database diagnosis of arthritis and its significant association with patient demographic, clinical, and functional characteristics highlights the limitation of use of these strategies for identification of patients with arthritis in epidemiological studies.