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Search Results: 1 - 10 of 1584 matches for " migratory waves "
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New evidence for human occupation of the northern Tibetan Plateau, China during the Late Pleistocene
BaoYin Yuan,WeiWen Huang,David Zhang
Chinese Science Bulletin , 2007, DOI: 10.1007/s11434-007-0357-z
Abstract: The described stone artifacts are recovered from the 70 m-high terrace (4600 m a.s.l.) at the southeastern shore of the Siling Co on the northern Tibetan Plateau. The terrace was formed during the Interstadial period before the LGM, ca. 40–30 ka B.P. based on paleoenvironmental research. The Paleoliths from the Siling Co provide evidence for early human occupation of the northern Tibetan Plateau. They show technological and typological affinities with the European Middle Paleolithic suggesting that the early human occupation here might relate to migratory waves during the Late Pleistocene that dispersed humans across the Old World.
Immigrant Detention Centres in Spain: a critical assessment
Adriana Jarrín Morán,Dan Rodríguez García,Javier de Lucas
Revista CIDOB d'Afers Internacionals , 2012,
Abstract: This paper presents a critical examination of the management of irregular migration flows in Spain and the legal principles and administrative practices implemented by the State in the process of expulsion that legitimise the existence of Immigrant Detention Centres (CIE). It also provides a description of the current situation of the CIE, and reports on the most recent proposals made by the Spanish government to improve the management of CIE in response to pressure exerted by civil society organisations, especially after public protests regarding the death of two inmates in December 2011 and January 2012.
The Herdsmen's Dilemma
Karma Ura
Journal of Bhutan Studies , 2002,
Abstract: Migratory herding is still an important part of the livelihood ofa significant section of the Bhutanese people; but it wascentral to our traditional pastoral economy. Cattle, grazingland, labour and cultivatable land were the four primarysources of wealth in the past. A balance among these fourfactors of production had to be struck for the agrarian societyto be sustained. Obviously, the area of grazing land, and thenumber of cattle depended on it, could not have been so largeas it was if forests were allowed to grow with rampant vigour,as we do now.Migratory herding embodies considerable empirical knowledgeabout ecology, climate and topography among the herdsmen,although this is not widely acknowledged. This fund ofknowledge have enabled the herdsmen to know the bestgrazing places and the most nutritious plants, which can beforaged by being at the right place in the right time, bymoving with precision. Being always out in the open, theherdsmen, and to some degree their cattle, have acuteperceptions of weather patterns. They have an acute sense oftiming to move from one place to another to avoid frost at apasture, or snowfall on a pass, or to escape the vampirishexperiences of ticks and leeches drilling into their eyes, noses,and groins.
Does Money Fly? The Economic Value of Migratory Birdwatching in Xochimilco, Mexico  [PDF]
Daniel A. Revollo-Fernández
Modern Economy (ME) , 2015, DOI: 10.4236/me.2015.66061
Abstract: This paper estimates the economic value that national and international birdwatchers have to keep an urban wetland in this case, Xochimilco (Mexico), as a place of rest, food and/or shelter for migratory birds from North America. For this purpose, it is resorted to surveys and contingent valuation that estimates the willingness to pay (WTP) per year of these watchers. The best estimate indicates that national watchers are willing to pay approximately US $79 per year, while international, US $296. Using these estimates, it is calculated that the economic value of the bird migration environmental service for this urban wetland is located between US $2836 and US $3999 per hectare. This found value can work as an input for decision makers when faced with projects and/or policies that may face different objectives.
Gravitational Waves: Present Status and Future Prospectus  [PDF]
Naseer Iqbal, Showkat Monga
Natural Science (NS) , 2014, DOI: 10.4236/ns.2014.65033
Abstract:

Remarkable progress has been made during recent years on the development of gravitational wave detectors. The review describes the present status and future prospectus of the gravitational wave astronomy. The main theme is to review the prominent long baseline detectors in operation around the world and proposed baseline and space-borne interferometers. Looking to the future, the major upgrades to the ground based detectors and new planned detectors will be completed over the coming years, which will create a network of detectors with the significantly improved sensitivity required to detect gravitational waves. Beyond this, the concept and design of possible future “third generation” gravitational-wave detectors will be discussed. Sources such as coalescing compact binary systems, neutron stars in low-mass X-ray binaries, stellar collapses and pulsars are all possible candidates for detection.

A presen?a de imigrantes de países do Cone Sul no Brasil: medidas e reflex?es
Sala, Gabriela Adriana;Carvalho, José Alberto Magno de;
Revista Brasileira de Estudos de Popula??o , 2008, DOI: 10.1590/S0102-30982008000200006
Abstract: this article estimates migratory balances of persons born in argentina, bolivia, chile, paraguay and uruguay in the 1980s and 1990s and who migrated to brazil. statistics were developed for brazil as a whole and for the brazilian states that have the highest proportions of populations of these immigrants. factors that may have affected the changes in volume and composition shown by immigrants from southern cone countries between 1980 and 2000 are also analyzed.
Capillary Wave’s Depth Decay  [PDF]
Kern E. Kenyon
Natural Science (NS) , 2014, DOI: 10.4236/ns.2014.616112
Abstract: Depth decay rates for pressure and velocity variations of a propagating capillary wave are found to be significantly different from each other, and neither one is expected to have the classical exponential character. To obtain these results Bernoulli’s equation along streamlines in the steady reference frame is combined with the force balance on fluid particles in the cross-stream direction: a pressure gradient offsets the centrifugal force on particles moving along a curved path. The two starting equations for pressure and velocity are nonlinear, but two linear first order ordinary differential equations are produced from them, one for each variable, and they can be integrated immediately. A full solution awaits further information on the non-constant coefficient, the radius of curvature function for the streamlines, either from observations or another theory.
Transparency of Cosmic Radio Waves Caused by Seismic and Volcano Activities  [PDF]
S. Koshevaya, Yu. Kotsarenko, J. A. Escobedo, A. Kotsarenko, V. Yutsis
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2014, DOI: 10.4236/jemaa.2014.611034
Abstract: The generation of different waves in the atmosphere and ionosphere caused by seismic and volcano activities has changed the transparency for cosmic radio waves. It is possible to analyze two cases: the first case caused by the atmospheric acoustic wave, which creates a periodic structure of the electron density in the ionosphere. It is shown that the resonant passing of the radio waves takes place, when the length of the acoustic wave is equal to one or a few lengths of the radio wave. The second case produces the electron density decrease in the F-layer of the ionosphere resulting in an increase in the transparency of the ionosphere for cosmic radio waves. The review of these phenomena is provided in this work and both cases have been confirmed experimentally.
Impact of the Waves on the Sea Surface Roughness under Uniform Wind Conditions: Idealized Cases for Uniform Winds (Part I)  [PDF]
José Augusto P. Veiga, M?nica R. Queiroz
Atmospheric and Climate Sciences (ACS) , 2015, DOI: 10.4236/acs.2015.53024
Abstract: The effect of the surface gravity waves over sea surface roughness length (z0) is investigated from several idealized numerical experiments with the Wave-Watch-III (WW3) model. The WW3 model is combined with a simplified model to estimate z0, CD, u* and U10 as function of the sea state. The impacts related to the presence of the ocean waves over z0 are obtained from conditions of growing (young waves) and mature seas (old waves). The wave spectrum is obtained from WW3 model for each idealized simulation under uniform wind conditions. Uniform wind experiments range from 15 to 45 m/s. The simplified algorithm determines z0, CD, u* and U10 for cases of young waves, old waves and by the Charnock method. The results show that when the ocean is characterized by young waves, both z0 and CD (drag coefficient) increase while U10 is reduced. In Charnock case, the values of z0, CD and U10 have no dependence with the presence of gravity waves. Experiments using winds higher than 30 m/s result in young waves’ CD values higher than the CD value for old waves. Even for young waves CD values are high for cases of strong winds. The results also show that in experiments using winds higher than 30 m/s the dependence between CD and wave age becomes stronger, which is in accordance with other studies.
Reproducción de peces y consideración de ambientes en eventos de crecidas en el río Portuguesa, Venezuela
Rodríguez-Olarte,Douglas; Kossowski,Christophe;
Bioagro , 2004,
Abstract: the reproduction of fishes in flooding events in the portuguesa river, venezuela, is reported. in the high plainlands (about 100 meter above sea level) and only at specific water speeds (higher than 0.59 m/s) eggs presenting embryonic stages between the four-cell-embryo and the phase of independent movement of the embryo were collected, suggesting that reproductive events occurred in a specific section of river associated to the geomorphological transition from foothills to the high plainlands. the eggs were incubated in laboratory and it was obtained mainly species of characiformes and siluriformes which are migratory fishes that make local movements of ascent and descent at the time of flooding. two basic aspects in the reproduction of fishes during floods are considered: magnitude of the water flow and areas of flood downstream. the regional fluvial ecosystems are put under severe impacts (dams, deforestation) that affect the survival of great part of ichthyofauna that reproduces during events of flooding. a special management of the section of the portuguesa river is suggested where the reproductive events take place.
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