نتایج جستجو برای: stream gradient
تعداد نتایج: 182720 فیلتر نتایج به سال:
Recent models on speech perception propose a dual-stream processing network, with a dorsal stream, extending from the posterior temporal lobe of the left hemisphere through inferior parietal areas into the left inferior frontal gyrus, and a ventral stream that is assumed to originate in the primary auditory cortex in the upper posterior part of the temporal lobe and to extend toward the anterio...
Question: How can vegetation gradients be described in riparian zones located in a species-rich mountain range and how do these gradients explain the variation found in the vegetation? Location: Hottentots Holland Mountains, Western Cape, South Africa. Methods: Three gradients (geographic, longitudinal, lateral) were defined to describe the complex vegetation patterns found here. The gradients ...
To define whether the beta diversity of stream invertebrate communities in New Zealand exhibits geographical variation unexplained by variation in gamma diversity and, if so, what mechanisms (productivity, habitat heterogeneity, dispersal limitation, disturbance) best explain the observed broad-scale beta diversity patterns. We sampled 120 streams across eight regions (stream catchments), spann...
We examined habitat factors related to reach-scale brook trout Salvelinus fontinalis counts of four size classes in two headwater stream networks within two contrasting summers in Connecticut, USA. Two study stream networks (7.7 and 4.4 km) were surveyed in a spatially continuous manner in their entirety, and a set of Bayesian generalised linear mixed models was compared. Trout abundance was be...
A computational model is proposed in order to explain how bottom-up and top-down signals are combined into a unified perception of figure and background. The model is based on the interaction between the ventral and the dorsal stream. The dorsal stream computes saliency based on boundary signals provided by the simple and the complex cortical cells. Output from the dorsal stream is projected to...
Title of document: INTERREGIONAL DIFFERENCES IN STREAM ECOSYSTEM RESPONSES TO URBANIZATION: CAUSES AND CONSEQUENCES Ryan Michael Utz, Doctor of Philosophy, 2010 Directed by: Dr. Robert H. Hilderbrand Program of Marine, Estuarine and Environmental Science Stream ecosystems are profoundly degraded by watershed urbanization. Hydrologic, geomorphic, chemical and thermal adjustment following urban d...
[1] We present stable oxygen isotope ratio (dO) measurements on deep-dwelling planktonic foraminifera from thewesternmargin of the North Atlantic in order to reconstruct the latitude at which the Gulf Stream separated from the western boundary of the Atlantic Ocean in the past. The modern separation latitude can be reconstructed within one degree from dO measured on the fossil shells of deep-dw...
Ionospheric two-stream waves and gradient-drift waves nonlinearly drive a large-scale (D.C.) current in the E-region ionosphere. This current flows parallel to, and with a comparable magnitude to, the fundamental Pedersen current. Evidence for the existence and magnitude of wave-driven currents derives from a theoretical understanding of E region waves, supported by a series of nonlinear 2-D si...
We examined UV-B radiation flux and its environmental control within and among streams of northern Michigan. UV-B flux was estimated in streams by plastic dosimetry strips, which allow for the simultaneous and repeated in situ measurement of solar radiation. During the summer of 2004, UV-B flux was measured across depth gradients and along longitudinal transects in seven streams, which were cho...
The aim of this study was to examine the effects of salinity on the survival and growth of a freshwater mussel Unio crassus, from a Mediterranean stream (Sarıçay Stream) in south-west Anatolia, Turkey, which has highly variable environmental conditions and a salinity gradient. A total of 250 similarly-sized U. crassus were collected from a stream in the species’ native range and transferred in ...
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