Hydrobiological variables as a regulatory factor on the abundance of heterotrophic flagellates in an urban pond     

Begum  Moni  Jewel  Md. Abu Sayed  Haque  Md. Ayenuddin  Khatun  Mst. Samsad 《中国海洋湖沼学报》2019,37(3):1030-1036

The seasonal abundance of flagellates has been monitored over a period of 1 year from December2013 to November 2014(divided into 4 conjugative seasons namely winter, spring, summer, and autumn) in an experimental pond located in Rajshahi City Corporation area, Bangladesh. To our knowledge, this study is the first to shed light on the occurrence and possible interrelationships among heterotrophic flagellates(HF),bacteria and zooplankton in Bangladesh and the result obtained by this study will be beneficial for similar water ecosystem all over the world. Standard methods were used to determine the prescribed hydrological parameters and zooplankton cell density. Maximum HF abundance(14 346.00 cells/mL) was found in the spring and the minimum(5 215.00 cells/mL) occurred in the summer. Inverse to HF, significantly(P0.05)higher zooplankton abundance was found during the winter(782.00±47.62 cells/mL) and the lowest value was found in the autumn(448.00±39.15 cells/mL). Whereas similar to the HF, total bacterial abundance was significantly higher during the spring((2.25±1.05)×10~5 cells/mL) and lower in the summer((0.79±0.06)×105 cells/mL). Multivariate analyses(ANOSIM and MDS) have shown significant seasonal differences for cell numbers where MDS ordination plot and cluster analysis based on similarity in the genera abundance of HF revealed overlapping condition between winter and spring. Canonical correspondence analysis(CCA) also showed a distinct separation among the genera based on the prevailing hydrological situation and indicated that temperature, pH, BOD_5, and NO_3~- were the most important environmental variables in determining the observed variation in HF community structure. Among the biological factors, zooplankton showed negative but total bacteria were positively correlated with HF abundance.  相似文献   

People and community as constituent parts of hazards: the significance of societal dimensions in hazards analysis     

C. Emdad Haque  David Etkin 《Natural Hazards》2007,41(2):271-282

Nature-triggered hazards and disasters have traditionally been treated only from the lens of geophysical and biophysical processes, implying that the root cause of large-scale death and destruction lies in the natural domain rather than in a coupled human–environment system. Conceptually, the physical domain has been seen as discrete and separate from human entities, and solutions were sought in the technological intervention and control of the physical environment—solutions that often ended up being less effective than hoped for and sometimes even counter productive. At all levels, institutions have directed and redirected most of their financial and logistical resources into the search for scientific and engineering solutions without allocating due attention and resources towards the assessment of effects and effectiveness of the applications of such technological outcomes. However, over the last two decades, forceful criticisms of the ‘dominant’ technocratic approach to hazards analysis have appeared in the literature and consequently there has not only been a shift in thinking of causation of disaster loss in terms of human vulnerability, but also newer questions have arisen regarding distinguishing between the ‘physical exposure’ of people to threats and societal vulnerability, and linking them with propensity to hazards loss. Though the vulnerability/resilience paradigm has largely replaced the hazards paradigm within the social sciences and much of the professional emergency and disaster management communities, this shift of thinking has not progressed to much of the physical science community, decision-makers and the public, who have not yet accepted the idea that understanding and using human and societal dimensions is equally or more important than trying to deal and control nature through the use of technology. This special issue is intended to further the idea that the aspects of community and peoples’ power to mitigate, to improve coping mechanisms, to respond effectively, and recover with vigor against the environmental extremes are of paramount conceptual and policy importance.  相似文献   

Preface     

C. Emdad Haque  David Etkin 《Natural Hazards》2007,41(2):269-270

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Climatic changes and desertification in some regions of the Middle East     

Shamsul Haque Alvi 《GeoJournal》1995,37(4):483-488

It is generally believed that more than 100 tropical countries are suffering from desertification or land degradation as a result of climatic changes. There is also concern that the rising temperature would lead to further environmental degradation and cause economic, social and other environmental impacts (1) in the Middle East. This paper is a modest attempt to investigate temperature and rainfall data in three countries of the Middle East (Oman, Bahrain, and Sudan) to determine if any change has taken place in the weather conditions. The short term environmental impact of the GulfWar in 1991 has been included in the study.The study confirms that temperatures are rising and rainfall is decreasing in Oman (2, 3) and other two countries, leading to increasing desertification processes. Here, following Hume and Kelly (4) desertification is taken to mean degradation in dryland regions or the permanent decline in the potential of the land to support biological activity and hence human welfare. A brief geographical discussion of Oman, Bahrain, and Sudan precedes a detailed analysis of temperatures and rainfall regimen in all three countries.  相似文献   

Laboratory modelling of shear behaviour of soft joints under constant normal stiffness conditions   总被引：1，自引：0，他引：1  

B. Indraratna  A. Haque  N. Aziz 《Geotechnical and Geological Engineering》1998,16(1):17-44

Shear behaviour of regular sawtooth rock joints produced from casting plaster are investigated under constant normal stiffness (CNS) conditions. Test results obtained in this investigation are also compared with the constant normal load (CNL) tests. It is observed that the peak shear stress obtained under CNL conditions always underestimates the peak shear stress corresponding to the CNS condition. Plots of shear stress against normal stress show that a nonlinear (curved) strength envelope is acceptable for soft rock joints subjected to a CNS condition, in comparison with the linear or bilinear envelopes often proposed for a CNL condition. Models proposed by Patton (1966) and Barton (1973) have also been considered for the predictions of peak shear stress of soft joints under CNS conditions. Although Patton's model is appropriate for low asperity angles, it overestimates the shear strength in the low to medium normal stress range at higher asperity angles. In contrast, while Barton's model is realistic for the CNL condition, it seems to be inappropriate for modelling the shear behaviour of soft joints under CNS conditions. The effect of infill material on the shear behaviour of the model joints is also investigated, and it is found that a small thickness of bentonite infill reduces the peak stress significantly. The peak shear stress almost approached that of the shear strength of infill when the infill thickness to asperity height ratio (t/a) reached 1.40. This paper also introduces an original, empirical shear strength envelope to account for the change in normal stress and surface degradation during CNS shearing. © Rapid Science Ltd. 1998  相似文献   

Hydrologic characteristics of floods in Ganges–Brahmaputra–Meghna (GBM) delta     

Akm Saiful Islam  Anisul Haque  Sujit Kumar Bala 《Natural Hazards》2010,54(3):797-811

In the middle of 2007, a severe flood affected the People’s Republic of Bangladesh. This is a natural disaster that takes people’s lives, destroys livestock, infrastructures and communication systems and, damages crops and fish ponds. Despite many adverse impacts, the flood situation is an accepted phenomenon to the citizens of Bangladesh, due to the immense increase of soil fertility due to the flood, plus, the recharge of aquifer, ecosystem and fish. The flood of 2007 was the 5th major flood of the last 20 years when more than thirty-five percent of the area of the country was inundated with flood water. As in the past, the flood of 2007 had its own significance. The geography of the country contains a floodplain delta of three major river basins: the Ganges, the Brahmaputra and the Meghna (GBM). The mean monthly rainfall plot from the TRMM satellite data has shown that for both the Meghna and Brahmaputra basins, the rainfall was higher during July 2007 than any other months of the last 2 years. This excess rainfall had accumulated in the Brahmaputra and Meghna rivers and carried downstream to Bangladesh. This was the main cause of the flooding in 2007. The first crossing above the danger level of the river waters was observed at Durgapur station of the Someswari and at Sunamganj station of the Surma on the nineteenth of July, 2007 inside Bangladesh. In terms of magnitude of the peak and duration of the flood, the Brahmaputra was higher in 2007 than during 2004. However, the Ganges river water level never crossed the danger level during flood of 2007. The Meghna was lower during the flood peak for the duration of the flood in 2007. The year–to-year variability in both the magnitude and duration of the flood suggests changes in rainfall and landuse pattern of the catchment.  相似文献   

Shear flow driven counter rotating vortices in an inhomogeneous dusty magnetoplasma     

W. Masood  Arshad M. Mirza  Aisha Ijaz  Q. Haque 《Astrophysics and Space Science》2014,349(2):829-834

The coupling of Shukla-Varma (SV) and convective cell modes is discussed in the presence of non-Boltzmannian electron response and parallel equilibrium shear flow. In the linear case, a new dispersion relation is derived and analyzed. It is found that the coupled SV and convective cell modes destabilize in the presence of electron shear flow. On the other hand, in the nonlinear regime, it is shown that Shukla-Varma mode driven counter rotating vortices can be formed for the system under consideration. It is found that these vortices move slowly by comparison with the ion acoustic or electron drift-wave driven counter rotating vortices. The relevance of the present investigation with regard to space plasmas is also pointed out.  相似文献   

Current-driven Alfvén waves in dusty magnetospheric plasmas     

S. Ali Shan  Q. Haque  H. Saleem 《Astrophysics and Space Science》2014,349(1):285-291

It is shown that the sheared flow of electrons and ions in the presence of heavy stationary dust gives rise to unstable Alfvén waves. The coupling of newly studied low frequency electrostatic current-driven mode with the electromagnetic Alfvén and drift waves is investigated. The instability conditions and the growth rates of both inertial and kinetic Alfvén waves are estimated. The theoretical model is applied to the night side boundary regions of Jupiter’s magnetosphere which contain positive dust. The growth rates increase with increase in sheared flow speed. In the nonlinear regime, both inertial and kinetic Alfvén waves form dipolar vortices whose speed and amplitude depend upon the magnitude of the zero-order current.  相似文献   

Development of analytical models to estimate the increase in pile capacity with time (pile setup) from soil properties     

Haque  Md. Nafiul  Abu-Farsakh  Murad Y. 《Acta Geotechnica》2019,14(3):881-905

This paper presents the analyses of twelve prestressed concrete (PSC) instrumented test piles that were driven in different bridge construction projects of Louisiana in order to develop analytical models to estimate the increase in pile capacity with time or pile setup. The twelve test piles were driven mainly in cohesive soils. Detailed soil characterizations including laboratory and in situ tests were conducted to determine the different soil properties. The test piles were instrumented with vibrating wire strain gauges, piezometers, pressure cells that were monitored during the whole testing period. Several static load tests (SLTs) and dynamic load tests were conducted on each test pile at different times after end of driving (EOD) to quantify the magnitude and rate of setup. Measurements of load tests confirmed that pile capacity increases almost linearly with the logarithm of time elapsed after EOD. Case pile wave analysis program was performed on the restrikes data and was used along with the load distribution plots from the SLTs to evaluate the increase in skin friction capacity of individual soil layers along the length of the piles. The logarithmic linear setup parameter “A” for unit skin friction was calculated of the 70 individual clayey soil layers and was correlated with different soil properties such as undrained shear strength (S_u), plasticity index, vertical coefficient of consolidation (c_v), over consolidation ratio and sensitivity (S_t). Nonlinear multivariable regression analyses were performed, and three different empirical models are proposed to predict the pile setup parameter “A” as a function of soil properties. For verification, the subsurface soil conditions and setup information for additional 18 PSC piles collected from local database were used to compare the measured versus predicted “A” parameters from the proposed models, which showed good agreement.

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Effects of convective available potential energy,temperature and humidity on the variability of thunderstorm frequency over Bangladesh     

Wahiduzzaman  Md  Ali  Md. Arfan  Luo  Jing-Jia  Wang  Yu  Uddin  Md. Jalal  Shahid  Shamsuddin  Islam  A. R. M. Towfiqul  Mondal  Sanjit Kumar  Siddiki  Ubaydur Rahaman  Bilal  Muhammad  Qiu  Zhongfeng  Dambul  Ramzah  Eibek  Kutubuddin  Haque  Md. Emdadul 《Theoretical and Applied Climatology》2022,147(1-2):325-346

Theoretical and Applied Climatology - The present study examines the effects of convective available potential energy (CAPE), temperature and humidity on the spatiotemporal variation of...  相似文献