Context-specific adaptation of vertical vergence to correlates of eye position

Vertical phoria (vertical vergence in the absence of binocular feedback) can be trained to vary with non-visual cues such as vertical conjugate eye position, horizontal conjugate eye position and horizontal vergence. These prior studies demonstrated a low-level association or coupling between vertical vergence and several oculomotor cues. As a test of the potential independence of multiple eye-position cues for vertical vergence, context-specific adaptation experiments were conducted in three orthogonal adapting planes (midsagittal, frontoparallel, and transverse). Four vertical disparities in each of these planes were associated with various combinations of two specific components of eye position. Vertical disparities in the plane were associated with horizontal vergence and vertical conjugate eye position; vertical disparities in the frontoparallel plane were associated with horizontal and vertical conjugate eye position; and vertical disparities in the transverse plane were associated with horizontal vergence and horizontal conjugate eye position. The results demonstrate that vertical vergence can be adapted to respond to specific combinations of two different sources of eye-position information. The results are modeled with an association matrix whose inputs are two classes of eye position and whose weighted output is vertical vergence.     

Noninvasive measurement of distal radius instability

Except for subjective clinical criteria, there is no formal definition of distal radius fracture instability in the literature. The purposes of this ex vivo biomechanical study were (1) to provide an objective mechanical definition of fracture instability and (2) to demonstrate a noninvasive method that allows for direct measurement of instability. The following 3 questions are addressed: (1) Can the stability of distal radius fractures be measured using computed tomography (CT)? (2) Are the stability measurements reproducible? (3) How does external fixation change stability? A CT technique is described that was used to measure displacement of fracture fragments and measure the compliance of ex vivo distal radius fractures before and after external fixation. Validation studies of the CT technique revealed a mean coefficient of variation of 0.38. There was a linear relationship between measured and known displacements for all 3 orthogonal planes (coefficient of determination 0.99; p < .01). There was significant fracture displacement with loads as small as 20 N. The slope of the load-displacement curve (structural compliance) provided a quantitative measure of fracture instability. Fracture compliance decreased up to 69% after application of an external fixator.     

Serotonin-deficient mutants and male mating behavior in the nematode Caenorhabditis elegans

Defining a behavior that requires the function of specific neurons in the free-living nematode Caenorhabditis elegans can allow one to screen for mutations that disrupt the specification or function of those neurons. We identified serotonin-immunoreactive neurons required for tail curling or "turning" behavior exhibited by C. elegans males during mating. Males mutant in three different genes that reduce serotonin expression, cat-1, cat-4, and bas-1, exhibited defects in turning behavior similar to those of wild-type males in which these neurons were ablated. The turning defect of cat-4 males was rescued by exogenous serotonin, consistent with the idea that their behavioral defect is caused by a lack of serotonin. While the serotonin-deficient mutants we analyzed shared certain behavioral traits, they were blocked for serotonin synthesis at different steps. Analysis of these and additional serotonin-deficient mutants may help us understand how a neuron controls the expression of a serotonergic phenotype.     

Applying a critical approach to investigate barriers to digital inclusion and online social networking among young people with disabilities

Despite the seeming ubiquity of young people's Internet use, there are still many for whom access to the Internet and online social networking remains inequitable and patterned by disadvantage. The connection between information technology and young people with disabilities is particularly under‐researched. This article contributes to the field of critical information systems research by exposing significant barriers and facilitators to Internet accessibility for young people with disabilities. It uses Bourdieu's critical theory to explore how the unequal distribution of resources shapes processes of digital inclusion for young people with disabilities. It highlights access needs and experiences that are both disability and non‐disability related. The article draws on interviews in South Australia with 18 young people aged 10–18 years with a physical disability (such as cerebral palsy) or acquired brain injury and with 17 of their family members. Interviews evaluated participants' and parents' reflections on the benefits of a home‐based, goal‐oriented intervention to increase the young person's Internet use for social participation purposes. The Bourdieuian analysis demonstrated how varying levels of accrued individual and family offline capital resources are related to digital/online resources and disability‐specific online resources. This revealed how unequal resources of capital can influence technology use and hence digital inclusion for young people with disabilities. Our study demonstrates that young people with particular types of disabilities require intensive, personalised and long‐term support from within and beyond the family to ‘get online’. We conclude that Internet studies need to more frequently adopt critical approaches to investigate the needs of users and barriers to information technology use within sub‐groups, such as young people with disabilities. © 2016 John Wiley & Sons Ltd     

Virulence of Aspergillus fumigatus double mutants lacking restriction and an alkaline protease in a low-dose model of invasive pulmonary aspergillosis

To investigate the pathogenicity of Aspergillus fumigatus mutants lacking putative virulence factors, we have developed a new murine model of invasive pulmonary aspergillosis based on neutropenia, the major factor predisposing patients to this infection. Mice were treated with cyclophosphamide and inoculated by the intranasal route with 5 x 10(3) conidia, a significant reduction from inoculum levels used in previous models. Evidence for the production of the extracellular alkaline protease (Alp) in lung tissue was obtained by using a fungal transformant harboring an alp::lacZ reporter gene fusion. The pathogenicities of single mutant strains lacking either Alp or the ribotoxin restrictocin and of a double mutant strain lacking both proteins were assessed in this infection model. There were no significant differences between the mutant and the wild-type strains in terms of mortality or histological-features. Inoculations with mixtures of conidia showed that the double mutant strain is slightly less virulent than the wild-type strain. We conclude that Alp and restrictocin are not important virulence determinants in pulmonary infection.     

Synthesis of 6-aziridinylbenzimidazole derivatives and their in vitro antitumor activities

In search for new antitumor agents, twelve 6-aziridinylbenzimidazole derivatives were synthesized and their cytotoxicities were tested against three cancer cell lines (mouse lymphocytic leukemia P388 and B16, and human gastric carcinoma SNU-16). From 4-amino-3-nitrotoluene as the starting material, 2-(acetoxymethyl)benzimidazoles (5a-d) were obtained by Phillips reaction. These benzimidazoles were then reacted with Fremy's salt to give a mixture of three 2-(acetoxymethyl) (8a-c) and four 2-(hydroxymethyl)benzimidazole-4,7-diones (9a-d). Addition of these quinones with aziridine afforded 6-aziridinyl-2-(acetoxymethyl) (10a-c) and 6-aziridinyl-2-(hydroxymethyl)benzimidazole-4,7-diones (11a-d). Utilizing 2-(hydroxymethyl)benzimidazole-4,7-diones (9b,d), esters 10d and 13e-h were prepared by the sequential reactions of esterification and addition. The synthesized compounds show potent cytotoxicity against all of three cell lines tested. The cytotoxicities of 10a-d or 11a-d against SNU-16 were superior to those of 13e-h, and were equal to or slightly higher than that of mitomycin C. Compounds 11a-d were slightly more cytotoxic than 10a-d in all cell lines tested.     

Chiasma interference as a function of genetic distance

For many organisms, meiotic double crossing over is less frequent than expected on the assumption that exchanges occur at random with respect to each other. This "interference," which can be almost total for nearby intervals, diminishes as the intervals in which the double crossovers are scored are moved farther apart. Most models for interference have assumed, at least implicitly, that the intensity of interference depends inversely on the physical distance separating the intervals. However, several observations suggest that interference depends on genetic distance (Morgans) rather than physical distance (base pairs or micrometers). Accordingly, we devise a model in which interference is related directly to genetic distance. Its central feature is that recombinational intermediates (C's) have two fates--they can be resolved with crossing over (Cx) or without (Co). We suppose that C's are distributed at random with respect to each other (no interference); interference results from constraints on the resolution of C's. The basic constraint is that each pair of neighboring Cx's must have between them a certain number of Co's. The required number of intervening Co's for a given organism or chromosome is estimated from the fraction of gene conversions that are unaccompanied by crossover of flanking markers. The predictions of the model are compared with data from Drosophila and Neurospora.     

Neurochemical alterations in asymptomatic abstinent cocaine users: a proton magnetic resonance spectroscopy study

Cocaine can cause a variety of neuropsychiatric and neurobehavioral complications; however, it is uncertain whether cocaine causes persistent cerebral structural and neurochemical abnormalities in asymptomatic users. We studied 52 African-American men (26 human immunodeficiency virus-negative asymptomatic heavy cocaine users and 26 normal subjects). Ventricle-to-brain ratio (VBR) and white matter lesions (WML) were quantified on magnetic resonance imaging. N-acetyl-containing compounds (NA), total creatine, choline-containing compounds, myo-inositol, and glutamate + glutamine were measured with in vivo proton magnetic resonance spectroscopy, VBR and WML were not significantly different in the cocaine users compared to the normal controls. Elevated creatine (+7%; p = .05) and myo-inositol (+18%; p = .01) in the white matter were associated with cocaine use. NA, primarily a measure of N-acetyl aspartate and neuronal content, was normal. Normal NA suggest no neuronal loss or damage in the brain regions examined in these cocaine users. Therefore, we conclude that neurochemical abnormalities observed might result from alterations in nonneuronal brain tissue.