Mechanisms of perceptual learning of depth discrimination in random dot stereograms.

Perceptual learning is a training induced improvement in performance. Mechanisms underlying the perceptual learning of depth discrimination in dynamic random dot stereograms were examined by assessing stereothresholds as a function of decorrelation. The inflection point of the decorrelation function was defined as the level of decorrelation corresponding to 1.4 times the threshold when decorrelation is 0%. In general, stereothresholds increased with increasing decorrelation. Following training, stereothresholds and standard errors of measurement decreased systematically for all tested decorrelation values. Post training decorrelation functions were reduced by a multiplicative constant (approximately 5), exhibiting changes in stereothresholds without changes in the inflection points. Disparity energy model simulations indicate that a post-training reduction in neuronal noise can sufficiently account for the perceptual learning effects. In two subjects, learning effects were retained over a period of six months, which may have application for training stereo deficient subjects.

Whole-body motion discrimination in the visually impaired

Visually impaired people show superior abilities in various perception tasks such as auditory attention, auditory temporal resolution, auditory spatial tuning, and odor discrimination. However, with the use of psychophysical methods, auditory and olfactory detection thresholds typically do not differ between visually impaired and sighted participants. Using a motion platform we investigated thresholds of passive whole-body motion discrimination in nine visually impaired participants and nine age-matched sighted controls. Participants were rotated in yaw, tilted in roll, and translated along the y-axis at two different frequencies (0.3 Hz and 2 Hz). An adaptive 3-down 1-up staircase procedure was used along with a two-alternative direction (leftward vs. rightward) discrimination task. Superior performance of visually impaired participants was found in the 0.3 Hz roll tilt condition. No differences between the visually impaired and controls were observed in all other types of motion. The superior performance in the 0.3 Hz roll tilt condition could reflect differences in the integration of extra-vestibular cues and increased sensitivity towards changes in the direction of the gravito-inertial force. In the absence of visual information, roll tilts entail a more pronounced risk of falling, and this could eventually account for the group difference. It is argued that differences in experimental procedures (i.e. detection vs. discrimination of stimuli) explain the discrepant findings across perceptual tasks comparing blind and sighted participants.

Light-quark and gluon jet discrimination in pp collisions at √s=7 TeV with the ATLAS detector

A likelihood-based discriminant for the identification of quark- and gluon-initiated jets is built and validated using 4.7 fb−1 √ of proton–proton collision data at √s = 7 TeV collected with the ATLAS detector at the LHC. Data sampleswith enriched quark or gluon content are used in the construction and validation of templates of jet properties that are the input to the likelihood-based discriminant. The discriminating power of the jet tagger is established in both data and Monte Carlo samples within a systematic uncertainty of ≈ 10–20 %. In data, light-quark jets can be tagged with an efficiency of ≈ 50% while achieving a gluon-jet mis-tag rate of ≈ 25% in a pT range between 40 GeV and 360 GeV for jets in the acceptance of the tracker. The rejection of gluon-jets found in the data is significantly below what is attainable using a Pythia 6Monte Carlo simulation, where gluon-jet mis-tag rates of 10% can be reached for a 50% selection efficiency of light-quark jets using the same jet properties.

Self-motion direction discrimination in the visually impaired

Despite the close interrelation between vestibular and visual processing (e.g., vestibulo-ocular reflex), surprisingly little is known about vestibular function in visually impaired people. In this study, we investigated thresholds of passive whole-body motion discrimination (leftward vs. rightward) in nine visually impaired participants and nine age-matched sighted controls. Participants were rotated in yaw, tilted in roll, and translated along the interaural axis at two different frequencies (0.33 and 2 Hz) by means of a motion platform. Superior performance of visually impaired participants was found in the 0.33 Hz roll tilt condition. No differences were observed in the other motion conditions. Roll tilts stimulate the semicircular canals and otoliths simultaneously. The results could thus reflect a specific improvement in canal–otolith integration in the visually impaired and are consistent with the compensatory hypothesis, which implies that the visually impaired are able to compensate the absence of visual input.

Rescue of neonatal cardiac dysfunction in mice by administration of cardiac progenitor cells in utero

Striated preferentially expressed gene (Speg) is a member of the myosin light chain kinase family. We previously showed that disruption of the Speg gene locus in mice leads to a dilated cardiomyopathy with immature-appearing cardiomyocytes. Here we show that cardiomyopathy of Speg(-/-) mice arises as a consequence of defects in cardiac progenitor cell (CPC) function, and that neonatal cardiac dysfunction can be rescued by in utero injections of wild-type CPCs into Speg(-/-) foetal hearts. CPCs harvested from Speg(-/-) mice display defects in clone formation, growth and differentiation into cardiomyocytes in vitro, which are associated with cardiac dysfunction in vivo. In utero administration of wild-type CPCs into the hearts of Speg(-/-) mice results in CPC engraftment, differentiation and myocardial maturation, which rescues Speg(-/-) mice from neonatal heart failure and increases the number of live births by fivefold. We propose that in utero administration of CPCs may have future implications for treatment of neonatal heart diseases.

Housing Discrimination in Metropolitan America: Findings from the Latest National Paired Testing Study

During the summer and fall of 2000, local fair housing organizations in twenty major metropolitan areas nationwide conducted a total of 4,600 paired tests, directly comparing the treatment that African Americans and Hispanics receive to the treatment that whites receive when they visit real estate or rental offices to inquire about available housing. This study, which was sponsored by the U.S. Department of Housing and Urban Development and conducted by the Urban Institute, provides the most complete and up-to-date information available about the persistence of housing market discrimination against African American and Hispanic homeseekers in large urban areas of the United States today and about the progress we have made in combating discrimination over the last decade.

Discrimination in Metropolitan Housing Markets Phase II: Asians and Pacific Islanders

This report documents the results of a an 11-city paired testing study by the Department of Housing and Urban Development of housing discrimination against Asian- Americans and Pacific Islanders. The study shows that one out of every five Asians and Pacific Islanders attempting to buy or rent a home are discriminated against, a rate similar to that of African Americans and Hispanics.

Discrimination in Metropolitan Housing Markets: National Results from Phase 1 of the Housing Discrimination Study (HDS)

The Housing Discrimination Study 2000 (HDS 2000) is the third nationwide effort sponsored by HUD to measure the amount of discrimination faced by minority home seekers. This report provides national estimates of discrimination faced by African Americans and Hispanics in 2000 as they searched for housing in the sales and rental markets. It also provides an accurate measure of how housing discrimination has changed since 1989. The report shows large decreases between 1989 and 2000 in the level of discrimination experienced by Hispanics and African Americans seeking to a buy a home. There are, however, worrisome upward trends of discrimination in the areas of geographic steering in home sales for African Americans and the amount of help agents provide to Hispanics with obtaining financing. There has also been a modest decrease in discrimination toward African Americans seeking to rent a unit. This downward trend, however, has not been seen for Hispanic renters. Hispanic renters now are more likely to experience discrimination in their housing search than do African American renters.

Other Things Being Equal: A Paired Testing Study of Discrimination in Mortgage Lending

This article summarizes a recently completed study, funded by the U.S. Department of Housing and Urban Development (HUD) and conducted by the Urban Institute, of discrimination against black and Hispanic homebuyers when they visit mortgage lending institutions in two major metropolitan markets to make pre-application inquiries. It represents the first application of paired testing to rigorously measure discrimination in the mortgage lending process. The paired tests disclosed significant levels of adverse treatment on the basis of race and ethnicity, with African Americans and Hispanics receiving less information and assistance than comparable whites, even at this very early stage in the application process.

Discrimination in Metropolitan Housing Markets: Phase 3 - Native Americans

This paper documents the results of a pilot paired testing program to examine the treatment of Native Americans by real estate agents in rental housing markets in three states and owner-occupied housing markets in one state. The study finds that the level of discrimination experienced by Native Americans in rental markets exceed those experienced by Hispanics, Blacks, and Asian-Americans.

Real-time image processing for crop/weed discrimination in maize fields

This paper presents a computer vision system that successfully discriminates between weed patches and crop rows under uncontrolled lighting in real-time. The system consists of two independent subsystems, a fast image processing delivering results in real-time (Fast Image Processing, FIP), and a slower and more accurate processing (Robust Crop Row Detection, RCRD) that is used to correct the first subsystem's mistakes. This combination produces a system that achieves very good results under a wide variety of conditions. Tested on several maize videos taken of different fields and during different years, the system successfully detects an average of 95% of weeds and 80% of crops under different illumination, soil humidity and weed/crop growth conditions. Moreover, the system has been shown to produce acceptable results even under very difficult conditions, such as in the presence of dramatic sowing errors or abrupt camera movements. The computer vision system has been developed for integration into a treatment system because the ideal setup for any weed sprayer system would include a tool that could provide information on the weeds and crops present at each point in real-time, while the tractor mounting the spraying bar is moving

Validation of microsatellite markers for cytotype discrimination in the model grass Brachypodium distachyon

Brachypodium distachyon (2n = 2x = 10) is a small annual grass species where the existence of three different cytotypes (10, 20 and 30 chromosomes) has long been regarded as a case of autopolyploid series, with x = 5. However, it has been demonstrated that the cytotypes assumed to be polyploids represent two separate Brachypodium species recently named as B. stacei (2n = 2x = 20) and B. hybridum (2n = 4x = 30). The aim of this study was to find a PCR-based alternative approach that could replace standard cytotyping methods (i. e., chromosome counting and flow cytometry) to characterize each of the three Brachypodium species. We have analyzed with four microsatellite (SSR) markers eighty-three Brachypodium distachyon-type lines from varied locations in Spain, including the Balearic and Canary Islands. Within this set of lines, 64, 4 and 15 had 10, 20 and 30 chromosomes, respectively. The surveyed markers produced cytotype-specific SSR profiles. So, a single amplification product was generated in the diploid samples, with non-overlapping allelic ranges between the 2n = 10 and 2n = 20 cytotypes, whereas two bands, one in the size range of each of the diploid cytotypes, were amplified in the 2n = 30 lines. Furthermore, the remarkable size difference obtained with the SSR ALB165 allowed the identification of the Brachypodium species by simple agarose gel electrophoresis.

Subtle atomic group discrimination in the RNA minor groove

As a problem in molecular recognition and for drug discovery, great interest has developed around the possibility that RNA structures could be discriminated by peptides and other small molecules. Although small peptides have been shown to have the capacity to discriminate specific bulges and loops in RNA molecules, discrimination of double helical regions by a peptide binder has not been reported. Indeed, the most accessible part of an RNA helix is the minor groove, and fundamental stereochemical considerations have suggested that discrimination of at least some base pairs would be difficult in the minor groove. Here we report the design and isolation of a peptide binder that manifests the most subtle kind of discrimination of base pair differences in the RNA minor groove. Functional discrimination of a single atomic group is demonstrated as well as the difference between two different angular orientations of the same group. This report of RNA helix discrimination by a peptide binder suggests a richer potential for RNA minor groove recognition than previously thought.