Showing 1–12 of 14 results
A two level mutation-selection model of cultural evolution and diversity
Cultural evolution iرایگان!
Cultural evolution is a complex process that can happen at several levels. At the level of individuals in a population, each human bears a set of cultural traits that he or she can transmit to its offspring (vertical transmission) or to other members of his or her society (horizontal transmission). The relative frequency of a cultural trait in a population or society can thus increase or decrease with the relative reproductive success of its bearers (individual’s level) or the relative success of transmission (called the idea’s level). This article presents a mathematical model on the interplay between these two levels. The first aim of this article is to explore when cultural evolution is driven by the idea’s level, when it is driven by the individual’s level and when it is driven by both. These three possibilities are explored in relation to (a) the amount of interchange of cultural traits between individuals, (b) the selective pressure acting on individuals, (c) the rate of production of new cultural traits, (d) the individual’s capacity to remember cultural traits and to the population size. The aim is to explore the conditions in which cultural evolution does not lead to a better adaptation of individuals to the environment. This is to contrast the spread of fitness-enhancing ideas, which make individual bearers better adapted to the environment, to the spread of ‘‘selfish’’ ideas, which spread well simply because they are easy to remember but do not help their individual bearers (and may even hurt them). At the same time this article explores in which conditions the adaptation of individuals is maximal. The second aim is to explore how these factors affect cultural diversity, or the amount of different cultural traits in a population. This study suggests that a larger interchange of cultural traits between populations could lead to cultural evolution not improving the adaptation of individuals to their environment and to a decrease of cultural diversity.
Climate Change, Human Impacts, and the Resilience of Coral Reefs
the ecosystem goodsرایگان!
the ecosystem goods and services they provide to maritime tropical and oral reefs are critically important for subtropical nations . Yet reefs are in serious decline; an estimated 30% are already severely damaged, and close to 60% may be lost by 2030 . There are no pristine reefs left . Local successes at protecting coral reefs over the past 30 years have failed to reverse regionalscale declines, and global management of reefs must undergo a radical change in emphasis and implementation if it is to make a real difference. Here, we review current knowledge of the status of coral reefs, the human threats to them now and in the near future, and new directions for research in support of management of these vital natural resources. Until recently, the direct and indirect effects of overfishing and pollution from agriculture and land development have been the major drivers of massive and accelerating decreases in abundance of coral reef species, causing widespread changes in reef ecosystems over the past two centuries . With increased human populations and improved storage and transport systems, the scale of human impacts on reefs has grown exponentially. For example, markets for fishes and other natural resources have become global, supplying demand for reef resources far removed from their tropical sources .
Climate change, related hazards and human settlements
The assessments of tرایگان!
The assessments of the Intergovernmental Panel on Climate Change (IPCC, 2007) have demonstrated that the climate is changing and the future will see higher sea levels, more heat waves, intense storms and heavy precipitation events and extension of drought areas. These climate hazards are having impacts on human settlements causing major loss of life, social disruption and economic hardship. Recent literature has demonstrated that the problem is more rather than less critical. Linking of climate change adaptation with disaster risk reduction is important and starting to happen although there are significant barriers. Less developed countries and the poorest people in all countries are those most at risk and usually with the least capacity to adapt and reduce risk. A new international research initiative, Integrated Research on Disaster Risk: addressing the challenge of natural and humaninduced environmental hazards (including climate change) has been established to meet the needs of providing an enhanced research base on which to develop and implement public policies .
Emerging Stormwater Controls for Critical Source Areas
An extensive literatرایگان!
An extensive literature review and survey of past and current drainage design practices during a recent EPA – funded research project found that design standards have not changed significantly during the past 25 years, but that there has been a shift towards the use of more sophisticated design tools (Pitt, et al. 1999). Unfortunately, current practices were identified as inadequately addressing water quality issues, even though almost all survey respondents recognized the significance of wet weather flow impacts. The use of long-term continuous simulation and addressing small storms that can be responsible for important receiving water quality problems is a recommended improvement in current design practices. Important changes in urban water management will also be needed in coming years to balance the needs for both water quality and quantity control in developing areas. This recent EPA research, along with many other current literature sources, found that it is possible and best to develop stormwater management design guidelines based on local rain conditions. Small events, making up the majority of rain events, commonly exceed bacteria and metal criteria, but are relatively easy to control through simple infiltration or on-site reuse of the stormwater. Moderate sized rains, however, are responsible for the majority of the runoff volumes and pollutant discharges. The runoff from these events can also be significantly reduced, but certainly not eliminated, through infiltration, but larger flows will have to be treated to reduce pollutant concentrations and excessive discharge rates. Large rains that approach and may exceed the capacities of the drainage system produce little of the annual flows and are rare. In addition, significant pollutant concentration reductions during these large events would be difficult and very expensive because of the very large flows involved. However, runoff flow rates should be reduced to produce instream flowrate distributions less than critical values in order to protect in-stream habitat.
Evaluating the influence of physical, economic and managerial factors on sheet erosion in rangelands of SW Spain by performing a sensitivity analysis on an integrated dynamic model
An integrated dynamiرایگان!
An integrated dynamic model was used to evaluate the influence of climatic, soil, pastoral, economic and managerial factors on sheet erosion in rangelands of SW Spain (dehesas). This was achieved by means of a variancebased sensitivity analysis. Topsoil erodibility, climate change and a combined factor related to soil water storage capacity and the pasture production function were the factors which influenced water erosion the most. Of them, climate change is the main source of uncertainty, though in this study it caused a reduction in the mean and the variance of long-term erosion rates. The economic and managerial factors showed scant influence on soil erosion, meaning that it is unlikely to find such influence in the study area for the time being. This is because the low profitability of the livestock business maintains stocking rates at low levels. However, the potential impact of livestock, through which economic and managerial factors affect soil erosion, proved to be greater in absolute value than the impact of climate change. Therefore, if changes in some economic or managerial factors led to higher stocking rates in the future, significant increases in erosion rates would be expected.
Geomorphologic hazards for Vanyar Dam with emphasis on the reactivation of Tabriz fault, northwest Iran
Shahid Madani or Vanرایگان!
Shahid Madani or Vanyar Dam is being construction on Aji Cahy River, to the north of Tabriz. It has been built on the upper red formation of Miocene. This lithology generally consists of sandstones, conglomerates, clays, and gypsum. Salt domes are also located underneath the reservoir area behind the dam. The slopes beside the reservoir are not stable. Unexpected events, such as subsidence, could occur after the reservoir is filled causing destruction to infrastructure. However, the most serious event could be the infiltration of water into the Tabriz fault. This fault has not been reactivated for over 220 years and it is thought that the infiltration of water from the reservoir could cause the two sides of the fault plane to move. It is thought that the displacement of the fault could cause an earthquake of more than 6.5 on the Richter scale. To try and prevent this fault reactivating, filling of reservoir is proposed to be undertaken gradually.
Paleoseismicity and new seismicity studies in Azerbaijan and the necessity for seismic zonation
Azerbaijan is the siرایگان!
Azerbaijan is the site of convergent plate collisions along the Alpine-Himalayan active mountain belt. Brittle faults in the Azerbaijan area are mostly Cenozoic in or younger. The data presented demonstrate clearly that geological structures are commonly repeated at all scales from outcrop to regional. In order to forecast earthquake activity we need to determine the past history of faults. A fault that is active is likely to move again. The great earthquakes of 6 May 1930 at 22 h 34 m. 24s (GMT) with M = 7.3 (the Salmas Earthquake), of 4 January 1780 with M = 7.7 (the Tabriz Earthquake) and of 21 June 1990 at a few minutes after midnight (local time) with a magnitude 7.4 (the Zanjan-Roudbar Earthquake) and located about 320 km NE of Tabriz, caused about 40 to 50 thousand deaths. 60000 were injured and 50000 to 60000 made homeless. These earthquakes have ruptured progressively from east to west. Consequently, there is a probability of a large earthquake occurrence in the North Tabriz Fault (NTF) and the central part of Tabriz to Khoy-Salmas fault. The average recurrence interval is estimated to be 250-300 years; more than 60-80 destructive earthquakes have been described in the 1000-1200 years in the history of Azerbaijan. Therefore, as there is a likelihood of large and dangerous earthquakes in Tabriz, micro-seismic zonation of the Tabriz and other seismic regions of Azerbaijan should be included in future construction planning of the country and it will be effective for the macroeconomic and industrial planning of the country.
Study the developments of international responsibility arising from environmental damage
Given the increasingرایگان!
Given the increasing importance of the environmental debate and the conservation and its conservation, the Issue of international Governments responsibility, is also very important in this issues. Since about the environment in different dimension and levels, many of the actions should not be performed, and some of the deeds and actions required to be done. (Criminal activity and non activity about environment). Surely this actions and non actions will be effective when will be accompanied with enforcement. There is doubt that we should know the introduction and enforcement of any provision by accepting International responsibility for related country. Of course this may seem so obvious and widespread that there is no need for talk and discussion about necessity of its existence. But it is important to remember that unfortunately, according to various causes, international responsibility arising from environmental damage Similar to other environmental issues, entered the realm of international law are rules by passing over a very long time and many ups and downs. In this way, we cannot still mention that topics of international responsibility in the field of environment is created completely and efficiently and will be used. Meanwhile, in recent years, many changes have occurred in different field and in the field of international responsibility arising from environmental damage, that we can have a lot of discussion about it and for making more efficient about this responsibility system in the field of environment, this developments and innovations must be known and used. In this paper we try to summarize the latest achievements in the field of international law with brief look at the past and more emphasis and attention to recent developments about international responsibility arising from environmental damage and based on the Basel Convention on pollution caused by transportation and excretion of hazardous waste.
The relationship between shear wave velocity, temperature, attenuation and viscosity in the shallow part of the mantle
Surface wave tomograرایگان!
Surface wave tomography, using the fundamental Rayleigh wave velocities and those of higher modes between 1 and 4 and periods between 50 and 160 s, is used to image structures with a horizontal resolution of ∼250 km and a vertical resolution of ∼50 km to depths of ∼300 km in the mantle .A new model, PM_v2_2012, obtained from 3× 106 seismograms, agrees well with earlier lower resolution models. It is combined with temperature estimates from oceanic plate models and with pressure and temperature estimates from the mineral compositions of garnet peridotite nodules to generate a number of estimates of SV(P, T) based on geophysical and petrological observations alone. These are then used to estimate the unrelaxed shear modulus and its derivatives with respect to pressure and temperature, which agree reasonably with values from laboratory experiments. At high temperatures relaxation occurs, causing the shear wave velocity to depend on frequency. This behaviour is parameterised using a viscosity to obtain a Maxwell relaxation time. The relaxation behaviour is described using a dimensionless frequency, which depends on an activation energy E and volume Va. The values of E and Va obtained from the geophysical models agree with those from laboratory experiments on high temperature creep. The resulting expressions are then used to determine the lithospheric thickness from the shear wave velocity variations. The resolution is improved by about a factor of two with respect to earlier models, and clearly resolves the thick lithosphere beneath active intracontinental belts that are now being shortened. The same expressions allow the three dimensional variations of the shear wave attenuation and viscosity to be estimated.
Uncertainty assessment of climate change impacts on the hydrology of small prairie wetlands
With increasing evidرایگان!
With increasing evidences of climate change in the prairie region, there is an urgent need to understand the future climate and the responses of small prairie wetlands. This study integrated two regional climate models (RCMs), two weather generators and a distributed hydrological model to examine uncertainties in hydrological responses to climate change in the Assiniboia watershed, Canada. Comparing to baseline conditions (1971–2000), annual water yield and evapotranspiration in the period of 2041–2070 were generally unchanged, while annual reservoir storage was generally reduced. However, projected hydrological regimes were less consistent at monthly level, particularly for March and July. Such uncertainties in simulated hydrological responses were derived from the implementations of different integrated downscaling methods, reflecting our imperfect knowledge of the future climate. We identified a warming temperature trend from climatic projections, but had less confidence in the future pattern of precipitation. Uncertainties in integrated downscaling were primarily derived from the choice of RCM, and were amplified through the incorporation of different weather generators. Results of any climate change study based on only one RCM and/or one weather generator should be interpreted with caution, and the ensemble framework should be advised to generate a comprehensive vision of the future climate. This study demonstrated that the incorporation of precipitation occurrence change contributed to a full translation of RCM outputs, but also introduced additional uncertainty. A balance is thus desired between the information loss and the additional uncertainty in order to effectively utilize RCM outputs .
ارائه روشی تلفیقی مبتنی بر الگوریتم كلونی مصنوعی زنبور عسل و پردازش تصویر برای شناسایی شکستگی ها در نمودار تصویری
شکستگی ها در مخازن ن...رایگان!
شکستگی ها در مخازن نفتی حوزه زاگرس نقش بنیادین در مهاجرت و تولید هیدروکربورها دارند. یکی از ابزارهای بسیار قوی برای مطالعه و شناسایی شکستگی ها در پیرامون چاه ها، نمودارهای تصویری است. این نمودارها اطلاعات مهمی درباره جهت گیری، ژرفا و نوع شکستگی های طبیعی فراهم میکنند. امروزه روش دقیقی برای شناسایی خودکار شکستگی ها از روی این نمودارها در مخازن کربناتی ایران وجود ندارد و تفسیر این نمودارها بیشتر به صورت دستی انجام میگیرد. بر این اساس در صورت نبود تجربه کافی، تفسیر با خطا روبه رو خواهد شد. هدف از مطالعه حاضر، معرفی و به کارگیری روشهای پردازش تصویر و الگوریتم کلونی مصنوعی زنبور عسل، برای پیدا کردن خودکار شکستگی ها در نمودارهای تصویری است. در این روش ابتدا با استفاده از یک روش ردهبندی، محل مربوط به شکستگی از درون تصویر استخراج میشود. سپس با استفاده از الگوریتم کلونی مصنوعی زنبورعسل، شیب، آزیموت و موقعیت ژرفی شکستگی ها از روی محل استخراج شده تعیین میشود. این روش روی نمودار تصویری FMSمربوط به یک چاه از میادین جنوب ایران پیاده سازی شده است. نتایج به صورت نمودار تراکم ژرفی، نمودار گلسرخی و استریونت شکستگی های شناسایی شده، نمایش داده شده است. نتایج حاصل کارایی راهکار پیشنهاد شده را نشان میدهد.
ارزیابی خواص پتروفیزیکی سازند آسماری میدان نفتی بزرگ مارون واقع درجنوب غرب کشور با استفاده از نگارهای چاه پیمایی
هدف از پژوهش حاضر بر...رایگان!
هدف از پژوهش حاضر بررسی کیفیت میدان نفتی مارون واقع در جنوب غرب کشور با استفاده از مطالعات پتروفیزیكی است. برای این منظور با استفاده از نگاره های چاه پیمایی و اطلاعات مغزه 1211داده نقطه ای و به کمک نرم افزار ،Geologپارامترهای پتروفیزیكی سازند آسماری در سه حلقه چاه B ،Aو Cاین میدان نفتی مورد ارزیابی قرار گرفت. با استفاده از نمودارهای متقاطع نوترون- چگالی و ،M-Nسنگ شناسی غالب سازند از نوع کربناته و به مقدار کمتر ماسه سنگ و شیل تشخیص داده شد. میزان تخلخل موثر متوسط سازند نیز در چاه های B ،Aو Cبه ترتیب برابر با 9/45 ،10/17و 8/15درصد و اشباع شدگی آب (Sw) سازند کمتری در فواصل سازنده ای ماسه سنگی نسبت به کربناته بدست آمد. براساس نتایج تحقیق کیفیت این مخزن درمجموع، متوسط و در فواصل عمقی ماسه سنگی از کیفیت بهتر و درنتیجه امكان عملیات تولید نفت بهتری برخوردار است.