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- Desa Mohamed, Mohamed Nor bin
(författare)
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Characterisation of Urban Rainfall in Kuala Lumpur, Malaysia
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rainfall characteristics of Kuala Lumpur, Malaysia, are studied in space and time; on a large scale, 550 km2, and long term scale to find out the monsoon influence, and on urban basin scale, 23 km2, to determine dynamic properties of rainfalls and spatial correlations, and on a point scale to determine the probabilities of very high rain intensities. The importance of spatial and temporal variability of rainfall was investigated applying cross correlation on long term historical rainfalls from Kuala Lumpur, Malaysia. Data from six rain gauges distributed over an area of 450 km2 were used. The annual and monthly rainfall correlation structures depict a pronounced effect of the monsoon. The variability of rainfall is parallel to the monsoon direction, which is perpendicular to the sea coast. The coefficient of variation for the monthly rainfalls is higher than for the annual rainfalls by a factor of two. Eight short term rainfall storms of 60 minute duration over the 23 km2 urban basin were studied to derive the average areal reduction factor curve. The results indicate that the structure of single rainfall cells is not very different from that in other climate regions. The areal reduction was well pronounced for a small urban catchment used in this study. Dynamic properties of 30 fully synchronised short term rainfall storms were investigated. The results showed significant correlation between storm velocities and observed wind velocities on the ground. The storm movements were rather slow. There was no correlation between storm movement and high altitude wind direction. The average storm velocity was 2.6 m/s compared to a mean velocity of 12 m/s obtained in high latitude regions by other investigators. A two-dimensional advection diffusion model was applied to two short term rainfall events for predicting rainfall intensities of one, three and five minutes ahead. The results enabled a reasonable physical explanation of model parameters. In addition, advection of the two rainfall events was carried out. However the results were not promising for prediction purposes. Partial duration series of short term rainfall storms recorded by seven rain gauges were analysed and empirical relationships for rainfall depths and intensity ratios as dependent variables against duration time as the independent variable were determined. The intensity-duration-frequency and the depth-duration-frequency relationship were applied to a surrounding area. Results showed that a modified intensity-duration-frequency relationship accounting for hourly rainfall intensities at the position under consideration is better than the depth-duration-frequency relationship.
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| 8. |
- Babiker-Mohamed, H, et al.
(författare)
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Alpha 1-microglobulin is mitogenic to human peripheral blood lymphocytes. Regulation by both enhancing and suppressive serum factors
- 1990
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Ingår i: Immunobiology. - 1878-3279. ; 180:2-3, s. 221-234
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Tidskriftsartikel (refereegranskat)abstract
- Human alpha 1-microglobulin (alpha 1-m), a 26 kilodalton serum glycoprotein, was found to exert mitogenic effects on human peripheral blood lymphocytes (PBL) in serum-free medium. Purified T cells, but not B cells, responded with proliferation to alpha 1-m, but only in the presence of monocytes. The mitogenic activity could be partially neutralized by a mouse monoclonal antibody against alpha 1-m. The mitogenicity was species-specific, since alpha 1-m homologues from rats, guinea pigs and rabbits had no effect on human PBL. In a previous study, no effect of alpha 1-m was seen on PBL in the presence of 20% serum, and, therefore, we studied the influence of different concentrations of serum on the alpha 1-m-induced mitogenicity. Thus, human serum enhanced the mitogenic effects of alpha 1-m on human PBL at 1% concentration (v/v) and suppressed the effects at 10%. The suppressing effect of serum at 10%, but not the enhancing effect at 1%, seemed to be conserved among several species. To test the effect of serum proteins of different molecular sizes, human autologous serum was separated by gel chromatography on Sephadex G-200 into four fractions. Fractions 1 and 2 (roughly containing proteins larger than 100 kilodaltons) suppressed the mitogenic effects of alpha 1-m, while fractions 3 and 4 enhanced the stimulation by alpha 1-m, at 0.5% and concentrations above. It is concluded that the mitogenic effect of alpha 1-m on lymphocytes is regulated by several serum factors, both enhancing and suppressive, that does not have any proliferative effect of their own. It can be speculated that the balance between enhancing and suppressing co-factors in the blood determines the degree of the stimulation of lymphocytes by alpha 1-m. This is compatible with an immunomodulatory role for alpha 1-m, in spite of its relatively constant plasma levels in health and disease.
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| 9. |
- Babiker-Mohamed, H, et al.
(författare)
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Characterization of monoclonal anti-alpha 1-microglobulin antibodies : binding strength, binding sites, and inhibition of lymphocyte stimulation
- 1991
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 1365-3083 .- 0300-9475. ; 34:5, s. 655-666
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Tidskriftsartikel (refereegranskat)abstract
- Eleven monoclonal antibodies (MoAb) directed against the immunoregulatory plasma glycoprotein alpha 1-microglobulin were characterized. The MoAb were produced in mice immunized with a mixture of alpha 1-microglobulin homologues from man, guinea pig, rat and rabbit. Using radioimmunoassay, western blotting, affinity chromatography, and Scatchard analysis, the affinities and binding sites of the MoAb were analysed. All antibodies were more or less cross-reactive, but most showed a major specificity for one or two of the alpha 1-microglobulin homologues. None of the antibodies was directed against the carbohydrate moiety of alpha 1-microglobulin. Six of the MoAb had high affinity for the antigen and four of these were directed towards the same part of the molecule though differing in their species specificity. Five showed lower affinity for the antigen and were mainly directed towards epitopes on other parts of the molecule. Only some of the antibodies could block the proliferation of lymphocytes induced by human alpha 1-microglobulin. The blocking efficiency of the different antibodies was similar when tested on the stimulation of human or mouse lymphocytes, suggesting that the same part of the alpha 1-microglobulin molecule is responsible in both species. The magnitude of blocking by the different MoAb was not related to their affinities, emphasizing the importance of where on the alpha 1-microglobulin molecule, rather than how strongly, they bind. The binding of the strongest blocking antibody was shown to be directed to a C-terminal peptide of rat alpha 1-microglobulin, indicating that this part of alpha 1-microglobulin is important for the mitogenic effects. Thus the panel of anti-alpha 1-microglobulin MoAb should be a valuable tool for structural and functional studies of alpha 1-microglobulin.
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| 10. |
- Babiker-Mohamed, H, et al.
(författare)
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Mitogenic effect of alpha 1-microglobulin on mouse lymphocytes. Evidence of T- and B-cell cooperation, B-cell proliferation, and a low-affinity receptor on mononuclear cells
- 1990
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 32:1, s. 37-44
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Tidskriftsartikel (refereegranskat)abstract
- Human alpha 1-m microglobulin (alpha 1-m), a low molecular weight plasma protein, was found to exert mitogenic effects on mouse lymphocytes from lymph nodes and spleen. The stimulatory effects appeared to be strain-restricted: alpha 1-m induced a varying degree of proliferation of lymphocytes from three strains, whereas one strain responded poorly. Experiments with lymphocyte subpopulations showed only weak stimulatory effects of alpha 1-m on purified T and B lymphocytes cultivated alone. The addition of mitomycin-treated cells of the other subpopulation could not restore the proliferative responses in either T or B lymphocytes. Strong stimulations were recorded only when both T and B lymphocytes were present, indicating that the T and B lymphocytes cooperate to achieve the proliferation. However, FACS studies on cultured splenocytes indicated that the proliferating cells are predominantly B lymphocytes. These data extend our earlier findings of a mitogenic effect of alpha 1-m on guinea pig lymphocytes. Furthermore, results were obtained indicating the presence of a receptor on mononuclear cells. Iodine-labelled alpha 1-m was bound to mononuclear cells prepared from spleens, and the binding could be blocked by an excess of non-labelled alpha 1-m. Scatchard plotting of the data gave an equilibrium constant of 0.7 x 10(5)/M for the binding between alpha 1-m and the receptor. Together with the documented inhibitory activity of alpha 1-m on antigen-driven proliferation of lymphocytes, these results suggest an immunoregulatory role for alpha 1-m.
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| 11. |
- Bagiev, G. L., et al.
(författare)
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Industrial marketing
- 1995
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Annan publikation (övrigt vetenskapligt/konstnärligt)
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| 14. |
- Bosch, Jan, et al.
(författare)
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Framework Problems and Experiences
- 1999
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Ingår i: Building Application Frameworks. - : Wiley & Sons. - 0471248754 ; , s. 55-82
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 15. |
- Brandén, Lars J., et al.
(författare)
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A peptide nucleic acid–nuclear localization signal fusion that mediates nuclear transport of DNA
- 1999
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Ingår i: Nature Biotechnology. - : Springer Science and Business Media LLC. - 1087-0156 .- 1546-1696. ; 17:8, s. 784-787
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Tidskriftsartikel (refereegranskat)abstract
- We have combined a peptide nucleic acid (PNA) with the SV40 core nuclear localization signal (NLS), to create a bifunctional PNA–NLS peptide. The PNA–NLS peptide increased the nuclear uptake of oligonucleotides and enhanced the transfection efficacy of plasmids. Gene expression from an enhanced green fluorescent protein plasmid and a lacZ plasmid was preserved when hybridized to PNA–NLS. In combination with the transfection agent polyethyleneimine, we have improved both the nuclear translocation of fluorescence-marked oligonucleotides, and the efficacy of plasmid transfection, up to eightfold. The technique obviates the use of cumbersome coupling procedures of the vector due to DNA–PNA duplex formation or displacement of the antisense plasmid DNA strand by a PNA molecule.
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| 33. |
- Chaib, Mohamed, et al.
(författare)
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Teacher’s Responsiveness Towards IT-based Learning
- 1997
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper discusses some basic aspects of computer-based education in Sweden. Reporting the results of three ongoing studies conducted at the University of Jšnkšping, the central roles played by the teachers in computer-based education is thoroughly analysed. The studies reported in this paper were all conducted at the comprehensive school level. In the first one, studentsÕ communicative interactions in front of the computer were compared to the interaction occurring in other forms of activities. The second study is concerned with the analysis of how students communicate between themselves when working with different types of software. Finally the third study is related to the analysis of teachersÕ Social representations of information technology in educational settings. In all three studies, we found evidence for the central roles teachers are playing in the process of monitoring communicative interactions in front of the computer. Our discussion will particularly address this aspect of IT-based learning. We furthermore find evidence for teachers ambivalence and confused representations of the computer as a technological teaching device. From these empirical evidence we discuss, in this paper, some possible outcomes for computer based learning in the future. We will particularly pay attention to the necessity of a better understanding and enhancing of teachersÕ preparedness for the roles they are expected to play in this important educational issue.
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| 38. |
- Diab, Khaled Mohamed
(författare)
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Quantification of skeletal, muscular and kinematics parameters in scoliosis : methodological and clinical studies
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation presents new methods derived for precise evaluation of a number of anatomical and functional variables of the complex thoracospinal deformity in scoliosis. By consensus the scoliotic angle at the frontal plane is measured on radiographs using the Cobb method. Another way of measuring this angle, the Ferguson method, although evidently more accurate than the Cobb, is not in use. The Cobb method uses only the declination of the upper and the lower vertebra of the curve to measure the degree of the curve. The Ferguson method uses the centroid of these two vertebrae and of the apical one to define the angle. In a derived new method the geometrical, i.e., the true, centre of the three vertebrae is defined on antero-posterior radiographs of the spine to delineate the scoliotic angle. Comparison of the measurements by the three methods in three groups of radiographs with different degrees of scoliosis shows that the new method gives higher accuracy and better repeatability than the two other methods. Studies on the vertebral growth under normal and pathological conditions are based on measurements of the vertebral height at different points of interest on radiographs, since there is no method for evaluation of the vertebral volume. A new stereological method is presented which allows estimation of the vertebral volume in vivo. The volume of one isolated normal and one scoliotic vertebra was measured in a model study using frontal and lateral radiographs and one CT-scan of each. The height of the vertebrae was measured at five points on the radiographs and was expressed as weighted circumferential height. Then the area of the vertebral body was measured using a grid on the CT-scan of the vertebra and the volume was calculated using the Cavallieri method. The accuracy of the measurements with the new method was high compared with serial CT-scans of the whole vertebra. The applicability of the method was evaluated in a series of scoliotic patients who had undergone posterior spinal instrumentation and fusion. The results showed that the weighted circumferential height of the three vertebrae had increased significantly at the last follow up on average 3 years after the operation. Also the volume of the apical vertebra was found to have increased, though not significantly. It is concluded that the proposed method provides accurate evaluation of vertebral body volume changes. The role of the intercostal muscles in the development of the thoracospinal deformity in scoliosis and of the respiratory movements of the thoracic cage is well recognised, but poorly studied because of lack of an accurate method for measurement of the surface area of the muscles and hence, indirectly, their function. In a model study the surface area of the intercostal muscles was evaluated in ultrasonographs and CT-scans by measurement of the area of their image either from the perpendiculars or by tracing. In both cases measurements of the surface area from the perpendiculars gave more accurate results than by tracing. The applicability of the method was tested in one healthy person during maximal inhalation and exhalation and no significant difference was found between the left and the right side during maximal inhalation or at full exhalation nor between full inhalation and exhalation for either side. To investigate if quantitative whole body movement analysis is a suitable method for motor control research a model study was developed to evaluate the kinematics of different spinal segments and of shoulder-link and pelvis displacement. Fourteen girls participated in the study; eight with right convex adolescent idiopathic scoliosis and six age-matched normal controls. The subjects were asked to stand on two force plates, and seventeen passive reflective markers were attached to certain anatomical landmarks on the dorsal aspect of their body. Six surface EMG electrodes were attached to the paraspinal and hip abductor muscles. The subjects were instructed to perform standardised voluntary trunk rotation and side bending to the left and right side. Simultaneous recording of the displacement of the markers with signals from plate forms recording the ground reaction force and the muscle activity was done. The results showed that the scoliotic group had a different way and strategy for orientation of different spinal segments displacement during voluntary trunk movements with a significant difference in the amplitude of the displacement of the centre of mass during side bending and during rotation of the trunk, compared with the control group. The resulting horizontal shear forces showed a significant difference between the two groups during side bending of the trunk, which was not the same during trunk rotation. The EMG study of the recorded activities from the paraspinal muscles and hip abductor muscles showed a different patterns and large variability between subjects and between the trials of each subject. In conclusion, this type of investigation helps to understand better the co-ordination of different body segments during voluntary movements and provides an adequate tool for investigation of spine movements and other trunk movements in normal as well as in scoliotic subjects.
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| 41. |
- Elneihoum, Ali Mohamed
(författare)
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Ischemic Cerebrovascular Disease: Risk Factors and Outcome Predictors with special reference to the role of leukocytes and inflammatory mediators
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ischemic cerebrovascular disease (CVD) is usually a consequence of atherosclerosis and is the commonest cause of stroke. The identification of risk factors and outcome predictors and the initiation of preventive measures constitute the cornerstone of efforts to reduce the risk of stroke and improve outcome. The trend for long-term outcome after stroke and the predictors of this outcome were evaluated in the light of data accumulated during the first four years after the founding of the Malmö Stroke Registry in 1989. Early predictors of ischemic CVD were studied in middle-aged, apparently healthy individuals, from the Malmö Prevention Project cohort. Since leukocytes are believed to play important parts regarding the risk and outcome of ischemic CVD, their possible involvement was the focus of special interest in this study. Although stroke incidence remained unchanged during the first four years of the Malmö stroke registry (1989-92), there was a trend toward a decline in the long-term recurrence and mortality rates following stroke. The long-term outcome predictors were evaluated. The age-standardized recurrence-free survival rate differs significantly between different residential areas in the city. In middle-aged, apparently healthy individuals, apart from traditional risk factors, a history of calf pain while walking (OR 1.9; p=0.002), a high serum uric acid level (OR 1.2; p<0.05) were found to be significant predictors of future ischemic CVD. In subjects with asymptomatic atherosclerosis (n=156), plasma levels of leukocyte activation markers neutrophil protease 4 (NP4), neutrophil gelatinase associated lipocalin (NGAL), tumor necrosis factor a (TNFa) and soluble TNF receptor-1 (sTNFR-1) were related to atherosclerosis risk factors (age, blood pressure, history of hypertension, and smoking). Patients with acute ischemic CVD (n=120) manifested higher plasma levels of NP4, NGAL and sTNFR-1 than did controls. During 4-year follow-up of patients with ischemic CVD (n=144) plasma levels of leukocyte activation markers at the time of acute cerebral ischemia, NGAL (OR 3.6; p<0.05) and sTNFR-1 (OR 2.0; p<0.01), were independent predictors of cardiovascular mortality. In conclusion, despite the observed trend of improving long-term outcome following stroke, the burden of this disease is still high. The observed variation of the long-term stroke free survival rate between different residential areas of the same city might be due to intra-urban differences in risk factor exposure or might indicate the importance of sociodemographic factors vis-à-vis long-term prognosis after stroke. Apart from traditional factors predicting ischemic CVD, the routine use of a simple questionnaire on calf pain while walking, and determination of the serum uric acid level might help in identifying those at high risk of ischemic CVD. Leukocyte activation seems to be an important factor both in atherosclerosis and ischemic CVD, and regarding outcome after ischemic CVD. The plasma levels of leukocyte activation markers might be useful in risk assessment, and possible targets for therapeutic medical intervention.
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| 42. |
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Ethnicity and the state in Eastern Africa
- 1998
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Anathematized and outlawed by African nationalism early in the postcolonial period, ethnicity has now eclipsed nationalism. It has proved by far the most potent force for political mobilization. The studies in this volume provide ample evidence of this potency of ethnicity. The authors focus on ethnicity's relationship to the state and try to account for the twists and turns that mark the history of this relationship.
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| 47. |
- Gabra, Mohamed, et al.
(författare)
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Development of a sugar cane residue feeding system for a cyclone gasifier
- 1998
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 15:2, s. 143-153
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Tidskriftsartikel (refereegranskat)abstract
- For the smooth and continuous operation of a cyclone gasifier, the fuel must be fed continuously and without interruption or large fluctuations. A feeding system for bagasse/cane trash powder was therefore designed, built and tested. It consisted of a feeding bin with four feeder screws in the bottom which deliver the fuel to two downcomers from which the fuel is injected by steam into the gasifier. During the first tests, the low bulk density and cohesive characteristics of a crushed bagasse/cane trash powder were found to cause an accumulation of the fuel in the feeding system, creating difficulties for the flow into the gasifier. In addition, once the flow of the crushed bagasse/cane trash powder is interrupted by a build-up in the downcomer channels, the crushed bagasse/cane trash powder becomes progressively compacted into a dense structure, resulting in blockage of the discharge. It was found possible to eliminate this problem by changing the shape of the slivers of the crushed bagasse/cane trash powder to render them more homogeneous. This was achieved by pelletizing the crushed bagasse or cane trash before grinding it to powder.
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| 48. |
- Gabra, Mohamed, et al.
(författare)
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Evaluation of new process options for co-generation in the sugar industry
- 1996
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Ingår i: 1996 International Gas Turbine and Aeroengine Congress and Exhibition. - : American Society of Mechanical Engineers. - 9780791878750
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Konferensbidrag (refereegranskat)abstract
- Biomass fuelled combined cycle with gas turbine for co-generation, has the promise of being able to produce electricity at competitive cost. The sugar cane industries in the developing countries are targets for near term-applications of this technology. Different options for increasing the electricity generation in the sugar mills by using more advanced steam process and combined cycle technology, using cane trash and bagasse as a fuel for has been analyzed. The TPC sugar mill in Tanzania was selected as a case study for investigation. Introduction of a combined gas turbine/steam turbine process will make it possible to increase the electricity output from 2.5 MW to 30 MW at this plant during milling season. By using cane trash as fuel during the off-season period, the electricity generation can be increased by a factor of 20 compared to what is generated at TPC sugar factory today. The financial evaluation indicated that the annual profit would range from USS 3.5 million for the advanced steam process with 6.5 years pay-back time, to be US$ 4.7 million for the combined gas turbine/steam turbine process with 6.8 years pay-back time
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| 49. |
- Gabra, Mohamed
(författare)
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Sugarcane Residual Fuels : a viable substitute for fossil fuels in the Tanzanian sugar industry
- 1995
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Ingår i: Renewable Energy for Development. - 1101-8267. ; 8:2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Before harvesting cane fields, cane wastes with an energy equivalent of up to four barrels of oil per acre are usually burnt. In many developing countries, this energy could be used to reduce dependence on fossil fuels as well as reduce the negative effects of global warming. A study at the Tanganyika Planting Company (TPC) sugar mill in Tanzania illustrates the possibilities of increasing power generation in a manner that is both economically and environmentally advantageous.
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