Size and shape constancy in consumer virtual reality

With the increase in popularity of consumer virtual reality headsets, for research and other applications, it is important to understand the accuracy of 3D perception in VR. We investigated the perceptual accuracy of near-field virtual distances using a size and shape constancy task, in two commercially available devices. Participants wore either the HTC Vive or the Oculus Rift and adjusted the size of a virtual stimulus to match the geometric qualities (size and depth) of a physical stimulus they were able to refer to haptically. The judgments participants made allowed for an indirect measure of their perception of the egocentric, virtual distance to the stimuli. The data show under-constancy and are consistent with research from carefully calibrated psychophysical techniques. There was no difference in the degree of constancy found in the two headsets. We conclude that consumer virtual reality headsets provide a sufficiently high degree of accuracy in distance perception, to allow them to be used confidently in future experimental vision science, and other research applications in psychology

Rationale and design of decision: a double-blind, randomized, placebo-controlled phase III trial evaluating the efficacy and safety of sorafenib in patients with locally advanced or metastatic radioactive iodine (RAI)-refractory, differentiated thyroid cancer

<p>Abstract</p> <p>Background</p> <p>The incidence of thyroid cancer and the number of patients who die from this disease are increasing globally. Differentiated thyroid cancer (DTC) is the histologic subtype present in most patients and is primarily responsible for the increased overall incidence of thyroid cancer. Sorafenib is a multikinase inhibitor that targets several molecular signals believed to be involved in the pathogenesis of thyroid cancer, including those implicated in DTC. In phase II studies of patients with DTC, sorafenib treatment has yielded a median progression-free survival (PFS) of 58 to 84 weeks and disease control rates of 59% to 100%. The DECISION trial was designed to assess the ability of sorafenib to improve PFS in patients with locally advanced or metastatic, radioactive iodine (RAI)-refractory DTC.</p> <p>Methods/design</p> <p>DECISION is a multicenter, double-blind, randomized, placebo-controlled phase III study in patients with locally advanced/metastatic RAI<b>-</b>refractory DTC. Study treatment will continue until radiographically documented disease progression, unacceptable toxicity, noncompliance, or withdrawal of consent. Efficacy will be evaluated every 56 days (2 cycles), whereas safety will be evaluated every 28 days (1 cycle) for the first 8 months and every 56 days thereafter. Following disease progression, patients may continue or start sorafenib, depending on whether they were randomized to receive sorafenib or placebo, at investigator discretion. Patients originally randomized to receive sorafenib will be followed up every 3 months for overall survival (OS); patients originally randomized to receive placebo will be followed up every month for 8 months after cross-over to sorafenib. The duration of the trial is expected to be 30 months from the time the first patient is randomized until the planned number of PFS events is attained. The primary endpoint is PFS; secondary endpoints include OS, time to disease progression, disease control rate, response rate, duration of response, safety, and pharmacokinetic analysis.</p> <p>Discussion</p> <p>The DECISION study has been designed to test whether sorafenib improves PFS in patients with locally advanced or metastatic RAI-refractory DTC.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov Identifier: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00984282">NCT00984282</a>; EudraCT: 2009-012007-25.</p

Magnitude, precision, and realism of depth perception in stereoscopic vision

Our perception of depth is substantially enhanced by the fact that we have binocular vision. This provides us with more precise and accurate estimates of depth and an improved qualitative appreciation of the three-dimensional (3D) shapes and positions of objects. We assessed the link between these quantitative and qualitative aspects of 3D vision. Specifically, we wished to determine whether the realism of apparent depth from binocular cues is associated with the magnitude or precision of perceived depth and the degree of binocular fusion. We presented participants with stereograms containing randomly positioned circles and measured how the magnitude, realism, and precision of depth perception varied with the size of the disparities presented. We found that as the size of the disparity increased, the magnitude of perceived depth increased, while the precision with which observers could make depth discrimination judgments decreased. Beyond an initial increase, depth realism decreased with increasing disparity magnitude. This decrease occurred well below the disparity limit required to ensure comfortable viewing

Structural Insights into the Evolution of a Non-Biological Protein: Importance of Surface Residues in Protein Fold Optimization

Phylogenetic profiling of amino acid substitution patterns in proteins has led many to conclude that most structural information is carried by interior core residues that are solvent inaccessible. This conclusion is based on the observation that buried residues generally tolerate only conserved sequence changes, while surface residues allow more diverse chemical substitutions. This notion is now changing as it has become apparent that both core and surface residues play important roles in protein folding and stability. Unfortunately, the ability to identify specific mutations that will lead to enhanced stability remains a challenging problem. Here we discuss two mutations that emerged from an in vitro selection experiment designed to improve the folding stability of a non-biological ATP binding protein. These mutations alter two solvent accessible residues, and dramatically enhance the expression, solubility, thermal stability, and ligand binding affinity of the protein. The significance of both mutations was investigated individually and together, and the X-ray crystal structures of the parent sequence and double mutant protein were solved to a resolution limit of 2.8 and 1.65 Å, respectively. Comparative structural analysis of the evolved protein to proteins found in nature reveals that our non-biological protein evolved certain structural features shared by many thermophilic proteins. This experimental result suggests that protein fold optimization by in vitro selection offers a viable approach to generating stable variants of many naturally occurring proteins whose structures and functions are otherwise difficult to study

What Do We Know About Neuropsychological Aspects Of Schizophrenia?

Application of a neuropsychological perspective to the study of schizophrenia has established a number of important facts about this disorder. Some of the key findings from the existing literature are that, while neurocognitive impairment is present in most, if not all, persons with schizophrenia, there is both substantial interpatient heterogeneity and remarkable within-patient stability of cognitive function over the long-term course of the illness. Such findings have contributed to the firm establishment of neurobiologic models of schizophrenia, and thereby help to reduce the social stigma that was sometimes associated with purely psychogenic models popular during parts of the 20th century. Neuropsychological studies in recent decades have established the primacy of cognitive functions over psychopathologic symptoms as determinants of functional capacity and independence in everyday functioning. Although the cognitive benefits of both conventional and even second generation antipsychotic medications appear marginal at best, recognition of the primacy of cognitive deficits as determinants of functional disability in schizophrenia has catalyzed recent efforts to develop targeted treatments for the cognitive deficits of this disorder. Despite these accomplishments, however, some issues remain to be resolved. Efforts to firmly establish the specific neurocognitive/neuropathologic systems responsible for schizophrenia remain elusive, as do efforts to definitively demonstrate the specific cognitive deficits underlying specific forms of functional impairment. Further progress may be fostered by recent initiatives to integrate neuropsychological studies with experimental neuroscience, perhaps leading to measures of deficits in cognitive processes more clearly associated with specific, identifiable brain systems

Dynamic Effective Connectivity of Inter-Areal Brain Circuits

Anatomic connections between brain areas affect information flow between neuronal circuits and the synchronization of neuronal activity. However, such structural connectivity does not coincide with effective connectivity (or, more precisely, causal connectivity), related to the elusive question “Which areas cause the present activity of which others?”. Effective connectivity is directed and depends flexibly on contexts and tasks. Here we show that dynamic effective connectivity can emerge from transitions in the collective organization of coherent neural activity. Integrating simulation and semi-analytic approaches, we study mesoscale network motifs of interacting cortical areas, modeled as large random networks of spiking neurons or as simple rate units. Through a causal analysis of time-series of model neural activity, we show that different dynamical states generated by a same structural connectivity motif correspond to distinct effective connectivity motifs. Such effective motifs can display a dominant directionality, due to spontaneous symmetry breaking and effective entrainment between local brain rhythms, although all connections in the considered structural motifs are reciprocal. We show then that transitions between effective connectivity configurations (like, for instance, reversal in the direction of inter-areal interactions) can be triggered reliably by brief perturbation inputs, properly timed with respect to an ongoing local oscillation, without the need for plastic synaptic changes. Finally, we analyze how the information encoded in spiking patterns of a local neuronal population is propagated across a fixed structural connectivity motif, demonstrating that changes in the active effective connectivity regulate both the efficiency and the directionality of information transfer. Previous studies stressed the role played by coherent oscillations in establishing efficient communication between distant areas. Going beyond these early proposals, we advance here that dynamic interactions between brain rhythms provide as well the basis for the self-organized control of this “communication-through-coherence”, making thus possible a fast “on-demand” reconfiguration of global information routing modalities

Evaluation of an outpatient diabetes Education Programme

The aim of this study was to evaluate a four-session multidisciplinary outpatient diabetes education programme using positive change in knowledge of diabetes, self-management behaviours, perceptions of wellness, body mass index and blood glucose control as indicators of programme efficacy. The participants were 24 patients (mean age 74 years, 17 male) with non-insulin- dependent diabetes mellitus. Data on their knowledge of diabetes, self- management behaviours, perceptions of wellness and body mass index were collected pre-programme and post-programme and at a 3-month follow-up. Glycosylated haemoglobin as a measure of blood glucose control was tested pre-programme and 3 months later. Analysis by Wilcoxon signed ranks test showed improvement in exercise behaviour between pre-programme and post- programme (