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51.
52.
Mahmud Sultan Sumana Ferdausi Mahojabin Mohsin Md Khan Md. Hasinur Rahaman 《Natural Hazards》2022,111(2):1863-1884
Natural Hazards - The knowledge of the climate pattern for a particular region is important for taking appropriate actions to alleviate the impact of climate change. It is also equally important... 相似文献
53.
Tanvir N. R. Le Floc’h E. Christensen L. Caruana J. Salvaterra R. Ghirlanda G. Ciardi B. Maio U. D’Odorico V. Piedipalumbo E. Campana S. Noterdaeme P. Graziani L. Amati L. Bagoly Z. Balázs L. G. Basa S. Behar E. De Cia A. Valle M. Della De Pasquale M. Frontera F. Gomboc A. Götz D. Horvath I. Hudec R. Mereghetti S. O’Brien P. T. Osborne J. P. Paltani S. Rosati P. Sergijenko O. Stanway E. R. Szécsi D. Tot́h L. V. Urata Y. Vergani S. Zane S. 《Experimental Astronomy》2021,52(3):219-244
Experimental Astronomy - At peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors are massive stars, they provide a tracer... 相似文献
54.
Amati L. O’Brien P.T. Götz D. Bozzo E. Santangelo A. Tanvir N. Frontera F. Mereghetti S. Osborne J. P. Blain A. Basa S. Branchesi M. Burderi L. Caballero-García M. Castro-Tirado A. J. Christensen L. Ciolfi R. De Rosa A. Doroshenko V. Ferrara A. Ghirlanda G. Hanlon L. Heddermann P. Hutchinson I. Labanti C. Le Floch E. Lerman H. Paltani S. Reglero V. Rezzolla L. Rosati P. Salvaterra R. Stratta G. Tenzer C. 《Experimental Astronomy》2021,52(3):183-218
Experimental Astronomy - THESEUS, one of the two space mission concepts being studied by ESA as candidates for next M5 mission within its Comsic Vision programme, aims at fully exploiting Gamma-Ray... 相似文献
55.
R. G. Abraham M. R. Merrifield R. S. Ellis N. R. Tanvir J. Brinchmann 《Monthly notices of the Royal Astronomical Society》1999,308(2):569-576
The frequency of barred spiral galaxies as a function of redshift contains important information on the gravitational influence of stellar discs in their dark matter haloes and may also distinguish between contemporary theories for the origin of galactic bulges. In this paper we present a new quantitative method for determining the strength of barred spiral structure, and verify its robustness to redshift-dependent effects. By combining galaxy samples from the Hubble Deep Field North with newly available data from the Hubble Deep Field South, we are able to define a statistical sample of 46 low-inclination spiral systems with I 814 W <23.2 mag. Analysing the proportion of barred spiral galaxies seen as a function of redshift, we find a significant decline in the fraction of barred spirals with redshift. The redshift distribution of 22 barred and 24 non-barred spirals with suitable inclinations is inconsistent with their being drawn from the same distribution at the 99 per cent confidence level. The physical significance of this effect remains unclear, but several possibilities include dynamically hotter (or increasingly dark-matter-dominated) high-redshift discs, or an enhanced efficiency in bar destruction at high redshifts. By investigating the formation of the 'orthogonal' axis of Hubble's classification tuning fork, our result complements studies of evolution in the early–late sequence, and pushes to later epochs the redshift at which the Hubble classification sequence is observed to be in place. 相似文献
56.
A. D. Mackey A. M. N. Ferguson M. J. Irwin N. F. Martin A. P. Huxor N. R. Tanvir S. C. Chapman R. A. Ibata G. F. Lewis A. W. McConnachie 《Monthly notices of the Royal Astronomical Society》2010,401(1):533-546
We report on deep imaging of a remote M31 globular cluster, MGC1, obtained with Gemini/GMOS. Our colour–magnitude diagram for this object extends ∼5 mag below the tip of the red-giant branch and exhibits features consistent with an ancient metal-poor stellar population, including a long, well-populated horizontal branch. The red-giant branch locus suggests MGC1 has a metal abundance [M/H]≈−2.3 . We measure the distance to MGC1 and find that it lies ∼160 kpc in front of M31 with a distance modulus μ= 23.95 ± 0.06 . Combined with its large projected separation of R p = 117 kpc from M31, this implies a deprojected radius of R gc = 200 ± 20 kpc , rendering it the most isolated known globular cluster in the Local Group by some considerable margin. We construct a radial brightness profile for MGC1 and show that it is both centrally compact and rather luminous, with MV =−9.2 . Remarkably, the cluster profile shows no evidence for a tidal limit and we are able to trace it to a radius of at least 450 pc, and possibly as far as ∼900 pc. The profile exhibits a power-law fall-off with exponent γ=−2.5 , breaking to γ=−3.5 in its outermost parts. This core-halo structure is broadly consistent with expectations derived from numerical models, and suggests that MGC1 has spent many gigayears in isolation. 相似文献
57.
Determinants of farmers’ choice of adaptation methods to climate change in the Nile Basin of Ethiopia 总被引:6,自引:0,他引:6
Temesgen Tadesse Deressa Rashid M. Hassan Claudia Ringler Tekie Alemu Mahmud Yesuf 《Global Environmental Change》2009,19(2):248-255
This study identifies the major methods used by farmers to adapt to climate change in the Nile Basin of Ethiopia, the factors that affect their choice of method, and the barriers to adaptation. The methods identified include use of different crop varieties, tree planting, soil conservation, early and late planting, and irrigation. Results from the discrete choice model employed indicate that the level of education, gender, age, and wealth of the head of household; access to extension and credit; information on climate, social capital, agroecological settings, and temperature all influence farmers’ choices. The main barriers include lack of information on adaptation methods and financial constraints. 相似文献
58.
Qiang Dai Dawei Han Miguel A. Rico‐Ramirez Lu Zhuo Nergui Nanding Tanvir Islam 《水文研究》2015,29(7):1704-1716
Radar‐based estimates of rainfall are affected by many sources of uncertainties, which would propagate through the hydrological model when radar rainfall estimates are used as input or initial conditions. An elegant solution to quantify these uncertainties is to model the empirical relationship between radar measurements and rain gauge observations (as the ‘ground reference’). However, most current studies only use a fixed and uniform model to represent the uncertainty of radar rainfall, without consideration of its variation under different synoptic regimes. Wind is such a typical weather factor, as it not only induces error in rain gauge measurements but also causes the raindrops observed by weather radar to drift when they reach the ground. For this reason, as a first attempt, this study introduces the wind field into the uncertainty model and designs the radar rainfall uncertainty model under different wind conditions. We separate the original dataset into three subsamples according to wind speed, which are named as WDI (0–2 m/s), WDII (2–4 m/s) and WDIII (>4 m/s). The multivariate distributed ensemble generator is introduced and established for each subsample. Thirty typical events (10 at each wind range) are selected to explore the behaviours of uncertainty under different wind ranges. In each time step, 500 ensemble members are generated, and the values of 5th to 95th percentile values are used to produce the uncertainty bands. Two basic features of uncertainty bands, namely dispersion and ensemble bias, increase significantly with the growth of wind speed, demonstrating that wind speed plays a considerable role in influencing the behaviour of the uncertainty band. On the basis of these pieces of evidence, we conclude that the radar rainfall uncertainty model established under different wind conditions should be more realistic in representing the radar rainfall uncertainty. This study is only a start in incorporating synoptic regimes into rainfall uncertainty analysis, and a great deal of more effort is still needed to build a realistic and comprehensive uncertainty model for radar rainfall data. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
59.
60.
Mirza A. T. M. Tanvir Rahman Ratan Kumar Majumder Syed Hafizur Rahman Md. Abdul Halim 《Environmental Earth Sciences》2011,63(2):363-373
Twenty groundwater samples were collected from two different areas in Satkhira Sadar Upazila to identify the source of salinity
in deep groundwater aquifer. Most of the analyzed groundwater is of Na–Cl–HCO3 type water. The trends of anion and cation are Cl− > HCO3
− > NO3
− > SO4
2− and Na+ > Ca2+ > Mg2+ > K+, respectively. Groundwater chemistry in the study area is mainly governed by rock dissolution and ion exchange. The dissolved
minerals in groundwater mainly come from silicate weathering. The salinity of groundwater samples varies from ~1 to ~5%, and
its source is possibly the paleo-brackish water which may be entrapped during past geologic periods. 相似文献