38,239 research outputs found
The optimal synapse for sparse, binary signals in the rod pathway:Neural Computation
No full textThe sparsity of photons at very low light levels necessitates a nonlinear synaptic transfer function between the rod photoreceptors and the rod-bipolar cells. We examine different ways to characterize the performance of the pathway: the error rate, two variants of the mutual information, and the signal-to-noise ratio. Simulation of the pathway shows that these approaches yield substantially different performance at very low light levels and that maximizing the signal-to-noise ratio yields the best performance when judged from simulated images. The results are compared to recent data.</p
From line to dots: an improved computerised rod and frame system for testing subjective visual vertical and horizontal
No full textBackground Perception of subjective visual vertical (SVV) and horizontal (SVH) has traditionally been measured by rotating a mechanical rod either with or without a frame present. The computerised rod and frame (CRAF) system has previously only been used to measure SVV. We have expanded the use of this system by testing its feasibility to measure SVH. This was done by comparing two groups of subjects (n = 103) randomly assigned to be tested for SVV or SVH. Findings Preliminary results showed a higher than expected percentage of individuals with SVH errors < 0.5°. This was attributed to additional visual cues provided by the changing appearance of the rod as it approached the horizontal. A solution to this problem was sought by replacing the rod by two dots to mark its ends. In a second investigation 30 subjects were tested using both the "rod as line" and "rod as dots" presentation. Bland and Altman analysis showed no difference between the rod and dots presentations in the measurement of SVV, but confirmed a fixed error of -0.93° between rods and dots for SVH. Changing the rod from a line to dots in the computer system resulted in errors for both SVV and SVH that were comparable to previous studies using manual systems. Conclusions The computerized rod and frame system may be improved by replacement of the line with two dots. This reduces clues provided to the subject by the appearance of the rod on the screen
Modelling Rod-like Flexible Biological Tissues for Medical Training
No full textThis paper outlines a framework for the modelling of slender rod-like biological tissue structures in both global and local scales. Volumetric discretization of a rod-like structure is expensive in computation and therefore
is not ideal for applications where real-time performance is essential. In our approach, the Cosserat rod model is introduced to capture the global shape changes, which models the structure as a one-dimensional entity, while the
local deformation is handled separately. In this way a good balance in accuracy and efficiency is achieved. These advantages make our method appropriate for
the modelling of soft tissues for medical training applications
Letter from Carl T. Hayden to C. H. Gensler, Havasupai Reservation
No full textLetter from Carl T. Hayden to C. H. Gensler, Havasupai Indian Reservation, regarding Hualapai and Cataract Canyons geography
Experimental investigation into the turbulence flowfield of in-flight round jets
No full textIn this paper, insight is provided into the modeling of single-point and two-point statistics of a subsonic round jet discharged into a moving ambient medium. An experimental campaign has been performed comprising two round, unheated air flows: a central jet at Mach number equal to 0.6 surrounded by a slower flight flow. Constant-temperature hot-wire anemometry was used to measure both the axial and radial velocity fluctuations within the turbulent jet flowfield. A Mach 0.6 jet was discharged into the flight flow, which ranged from zero up to Mach 0.3. The data show that the degree to which the jet stretches with increasing flight velocity can be discerned with the knowledge of the decay of the mean velocity field downstream of the end of the jet’s potential core. This stretching factor can then be used to predict the changes in the static jet turbulence statistics for the in-flight case. Additionally, in the region of high-turbulence kinetic energy, the two-point statistics can be estimated using information about the single-point statistics and the local mean velocity. Empirical models for the in-flight jet’s shear stresses, cross-correlations, and power spectral density functions are presented and compared with those derived for the static jet case
Involvement of the lamin rod domain in heterotypic lamin interactions important for nuclear organization
No full textThe nuclear lamina is a meshwork of intermediate-type filament proteins (lamins) that lines the inner nuclear membrane. The lamina is proposed to be an important determinant of nuclear structure, but there has been little direct testing of this idea. To investigate lamina functions, we have characterized a novel lamin B1 mutant lacking the middle approximately 4/5 of its alpha-helical rod domain. Though retaining only 10 heptads of the rod, this mutant assembles into intermediate filament-like structures in vitro. When expressed in cultured cells, it concentrates in patches at the nuclear envelope. Concurrently, endogenous lamins shift from a uniform to a patchy distribution and lose their complete colocalization, and nuclei become highly lobulated. In vitro binding studies suggest that the internal rod region is important for heterotypic associations of lamin B1, which in turn are required for proper organization of the lamina. Accompanying the changes in lamina structure induced by expression of the mutant, nuclear pore complexes and integral membrane proteins of the inner membrane cluster, principally at the patches of endogenous lamins. Considered together, these data indicate that lamins play a major role in organizing other proteins in the nuclear envelope and in determining nuclear shape
Letter from Charles H. Burke to Carl Hayden
No full textLetter from Charles H. Burke to Carl T. Hayden about mining on Diné (formerly Navajo) national land
Piston Rod Connection
No full textPatent for a connector between a cross-head and a piston-rod that reduces strain by using a double taper and binder elements in line with the thrust of the piston-rod to prevent fractures and breaks as a result of the end thrust
Letter from John H. Page to Carl Hayden
No full textLetter from John H. Page to Carl T. Hayden regarding his company's rights to build a railway if they choose to
Intent to Speed: Cyclical Production, Topicality and the 1950s Hot Rod Movie
No full textThis essay tracks the emergence, consolidation and dissolution of the short cycle of hot rod movies that was exhibited from 1956 to 1958. The aim is to explore this cycle’s connection to topical issues and show how filmmakers used timely subjects. The essay examines the media frenzy that whirled around the subculture of hot rodding and the sensationalist marketing strategies used to promote the films, which are linked to exhibition in drive-in theatres. There is an extraordinary mismatch between the thrills promised by the sales pitch for the films and the pedestrian action of the films themselves. While showing intent to speed, few examples of the cycle actually delivered on the promise to thrill. Finally, questions of turnover and the speed of production are considered. What draws these areas of interest together is a series of enquiries about what made hot rods and hot rod culture useful to film producers and audiences
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