Natural hazards lead to unexpected and often dire situations for people who have few resources and little control over the environment in which they live. Kutubdia, an island in the southeastern part of Bangladesh, experiences frequent natural hazards that impact the livelihoods of its people and put them in vulnerable situations. The research elaborated here is the result of 300 household surveys collected from persons in Kutubdia's fishing communities. The surveys investigated the perception and consequences of natural hazards on the fishing communities. The results indicated that the experience of natural hazards—cyclones, erosion, and flooding are examples—have increased over the years. Coastal erosion displaced seventy‐two (24 percent) fishers, forcing them to relocate their houses several times and imposing multiple challenges on their lives. Literacy was not associated with perceptions of environmental changes or changes in fishing. However, young fishers—less than forty years of age—perceived that environmental changes had affected fish catch more than their older colleagues. 相似文献
Abstract The paper discusses aspects of the isotopic composition (tritium and stable isotopes) of precipitation, which was monitored from 2000 to 2003 at 12 stations in Syria. The seasonal variations in δ18O are smaller at the western stations than at the eastern ones due to low seasonal temperature variations. A good correlation between δ2H and δ18O was obtained for each station, and the slopes of the local meteoric water lines are significantly lower than the Global Meteoric Water Line. Values of d-excess decrease from 19‰ at the western stations to 13‰ at the eastern ones, indicating the influence of precipitation generated by air masses coming from the Mediterranean Sea. A reliable altitude effect represented by depletion of heavy stable isotopes (δ18O and δ2H), of about??0.21‰ and??1.47‰ per 100 m elevation, respectively, was observed. Monthly tritium contents in precipitation, and seasonal variations, are less at the western stations than at the eastern ones. The weighted mean tritium values are between 3 and 9 TU, and increase with distance from the Syrian coast by 1 TU/100 km. Citation Al Charideh, A. R. & Abou Zakhem, B. (2010) Distribution of tritium and stable isotopes in precipitation in Syria. Hydrol. Sci. J.55(5), 832–843. 相似文献
The currently adopted rainfall-based design flood estimation method in Australia, known as design event approach (DEA), has a flaw that is widely criticized by the hydrologists. The DEA is based on the assumption that a rainfall depth of a certain frequency can be transformed to a flood peak of the same frequency by adopting the ‘representative values’ of other model input variables, such as temporal patterns and losses. To overcome the limitation associated with the DEA, this paper develops stochastic model inputs to apply Monte Carlo simulation technique (MCST) for design flood estimation. This uses data from 86 pluviograph stations and six catchments from eastern New South Wales (NSW), Australia, to regionalize the distributions of various input variables (e.g., rainfall duration, inter-event duration, intensity and temporal patterns and loss and routing characteristics) to simulate thousands of flood hydrographs using a nonlinear runoff routing model. The regionalized stochastic inputs are then applied with the MCST to two catchments in eastern NSW. The results indicate that the developed MCST provide more accurate flood quantile estimates than the DEA for the two test catchments. The particular advantage of the new MCST and stochastic design input variables is that it reduces the subjectivity in the selection of model input values in flood modeling. The developed MCST can be adapted to other parts of Australia and other countries. 相似文献
In present study a turbocharged, medium duty compression ignition engine was alternatively fuelled with biodiesel to investigate the changes in particulate matter composition, relative to that taken with diesel fuel. The engine was operated on an AC electrical dynamometer in accordance with an 8-mode, steady-state cycle. The numbers of particles were estimated through electrical low pressure impactor, while sulfates and trace metals were analyzed by ion chromatography and inductively coupled plasma-atomic emission spectroscopy, respectively. Nitric oxides and nitrogen dioxides were measured separately using SEMTECH-DS. Experimental results revealed that, on account of elevated ratios of nitrogen dioxide to nitrogen oxides, mean accumulation mode particles were 42 % lower with biodiesel. On the other hand, nuclei mode particles were higher with biodiesel, owing to heterogeneous nucleation and accounting for an increase in sulfate emissions up to 8 % with biodiesel as compared to diesel. On the average, trace metal emissions were significantly reduced showing 65–85.4 % reduction rates with biodiesel, relative to its counterpart. Further to this, individual congeners such as iron, calcium, and sodium were the predominant elements of the trace metals emitted from engine. The mean relative decrease in iron and calcium was 89–97.8 and 77.6–87 %, respectively, while the relative rise in sodium was in the range of 29–46 % with biodiesel. Further, elements such as zinc, chromium, and aluminum showed substantial abatement, whereas potassium, magnesium, and manganese exhibited irregular trends on account of variable engine loads and speeds during the various modes of cycle. 相似文献
The Gamow-Teller strength distribution function, B(GT), for the odd Z parent 51V, N?Z=5, up to 30 MeV of excitation energy in the daughter 51Ti is calculated in the domain of proton-neutron Quasiparticle Random Phase Approximation (pn-QRPA) theory. The pn-QRPA results are compared against other theoretical calculations, (n, p) and high resolution (d, 2He) reaction experiments. For the case of (d, 2He) reaction the calibration was performed for 0≤Ej≤5.0 MeV, where the authors stressed that within this excitation energy range the ΔL=0 transition strength can be extracted with high accuracy for 51V. Within this energy range the current pn-QRPA total B(GT) strength 0.79 is in good agreement with the (d, 2He) experiment’s total strength of 0.9±0.1. The pn-QRPA calculated Gamow-Teller centroid at 4.20 MeV in daughter 51Ti is also in good agreement with high resolution (d, 2He) experiment which placed the Gamow-Teller centroid at 4.1±0.4 MeV in daughter 51Ti. The low energy detailed Gamow-Teller structure and Gamow-Teller centroid play a sumptuous role in associated weak decay rates and consequently affect the stellar dynamics. The stellar weak rates are sensitive to the location and structure of these low-lying states in daughter 51Ti. The calculated electron capture rates on 51V in stellar matter are also in good agreement with the large scale shell model rates. 相似文献
Gamow-Teller (GT) transitions play a preeminent role in the collapse of stellar core in the stages leading to a Type-II supernova. The microscopically calculated GT strength distributions from ground and excited states are used for the calculation of weak decay rates for the core-collapse supernova dynamics and for probing the concomitant nucleosynthesis problem. The B(GT) strength for 57Zn is calculated in the domain of proton-neutron Quasiparticle Random Phase Approximation (pn-QRPA) theory. No experimental insertions were made (as usually made in other pn-QRPA calculations of B(GT) strength function) to check the performance of the model for proton-rich nuclei. The calculated B(GT) strength distribution is in good agreement with measurements and shows differences with the earlier reported shell model calculation. The pn-QRPA model reproduced the measured low-lying strength for 57Zn better in comparison to the KB3G interaction used in the large-scale shell model calculation. The stellar weak rates are sensitive to the location and structure of these low-lying states in daughter 57Cu. The structure of 57Cu plays a sumptuous role in the nucleosynthesis of proton-rich nuclei. The primary mechanism for producing such nuclei is the rp-process and is believed to be important in the dynamics of the collapsing supermassive stars. Small changes in the binding and excitation energies can lead to significant modifications of the predictions for the synthesis of proton rich isotopes. The ??+-decay and electron capture (EC) rates on 57Zn are compared to the seminal work of Fuller, Fowler and Newman (FFN). The pn-QRPA calculated ??+-decay rates are generally in good agreement with the FFN calculation. However at high stellar temperatures the calculated ??+-decay rates are almost half of FFN rates. On the other hand, for rp-process conditions, the calculated electron capture (??+-decay) rates are bigger than FFN rates by more than a factor 2 (1.5) and may have interesting astrophysical consequences. 相似文献
Palaeontology was established as a science in the Victorian era, yet has roots that stretch deeper into the recesses of history. More than 2000 years ago, the Greek philosopher Aristotle deduced that fossil sea shells were once living organisms, and around 500 ad Xenophanes used fossils to argue that many areas of land must have previously been submarine. In 1027, the Persian scholar Avicenna suggested that organisms were fossilized by petrifying fluids; this theory was accepted by most natural philosophers up until the eighteenth century Enlightenment, and even beyond. The late 1700s were notable for the work of Georges Cuvier who established the reality of extinction. This, coupled with advances in the recognition of faunal successions made by the canal engineer William Smith, laid the framework for the discipline that would become known as palaeontology. As the nineteenth century progressed, the scientific community became increasingly well organized. Most fossil workers were gentleman scientists and members of the clergy, who self‐funded their studies in a new and exciting field. Many of the techniques used to study fossils today were developed during this ‘classical’ period. Perhaps the most fundamental of these is to expose a fossil by splitting the rock housing it, and then conduct investigations based upon the exposed surface ( Fig. 1 ). This approach has served the science well in the last two centuries, having been pivotal to innumerable advances in our understanding of the history of life. Nevertheless, there are many cases where splitting a rock in this way results in incomplete data recovery; those where the fossils are not flattened, but are preserved in three‐dimensions. Even the ephemeral soft‐tissues of organisms are occasionally preserved in a three‐dimensional state, for example in the Herefordshire, La Voulte Sûr Rhone and Orsten ‘Fossil Lagerstätten’ (sites of exceptional fossil preservation). These rare and precious deposits provide a wealth of information about the history of life on Earth, and are perhaps our most important resource in the quest to understand the palaeobiology of extinct organisms. With the aid of twenty‐first century technology, we can now make the most of these opportunities through the field of ‘virtual palaeontology’—computer‐aided visualization of fossils. Figure 1 Open in figure viewer PowerPoint A split nodule showing the fossil within, in this case a cockroachoid insect. Fossil 4 cm long (From Garwood & Sutton, in press ). 相似文献
Bangladesh is one of the most vulnerable countries to natural disasters such as droughts in the world. The pre-monsoon Aus rice in Bangladesh depends on rainfall and is threatened by increasing droughts. However, limited information on the changes in Aus rice as well as droughts hamper our understanding of the country’s agricultural resilience and adaption to droughts. Here, we collected all the official statistical data of Aus rice at the district level from 1980 to 2018, and examined the inter... 相似文献
