Knowledge-Driven Contrast Gain Control is Characterized by Two Distinct Electrocortical Markers

Sensitivity to variations in luminance (contrast) is fundamental to perception because contrasts define the edges and textures of visual objects. Recent research has shown that contrast sensitivity, in addition to being controlled by purely stimulus-driven mechanisms, is also affected by expectations and prior knowledge about the contrast of upcoming stimuli. The ability to adjust contrast sensitivity based on expectations and prior knowledge could help to maximize the information extracted when scanning familiar visual scenes. In the present study we used the event-related potentials (ERP) technique to resolve the stages that mediate knowledge-driven aspects of contrast gain control. Using groupwise independent components analysis and multivariate partial least squares, we isolated two robust spatiotemporal patterns of electrical brain activity associated with preparation for upcoming targets whose contrast was predicted by a cue. The patterns were sensitive to the informative value of the cue. When the cues were informative, these patterns were also able to differentiate among cues that predicted low-contrast targets and cues that predicted high-contrast targets. Both patterns were localized to parts of occipitotemporal cortex, and their morphology, latency, and topography resembled P2/N2 and P3 potentials. These two patterns provide electrophysiological markers of knowledge-driven preparation for impending changes in contrast and shed new light on the manner in which top-down factors modulate sensory processing

Solving the Traveling Telescope Problem with Mixed Integer Linear Programming

The size and complexity of modern astronomical surveys has grown to the point where, in many cases, traditional human scheduling of observations are tedious at best and impractical at worst. Automated scheduling algorithms present an opportunity to save human effort and increase scientific productivity. A common scheduling challenge involves determining the optimal ordering of a set of targets over a night subject to timing constraints and time-dependent slew overheads. We present a solution to the `Traveling Telescope Problem' (TTP) that uses Mixed-Integer Linear Programming (MILP). This algorithm is fast enough to enable dynamic schedule generation in many astronomical contexts. It can determine the optimal solution for 100 observations within 10 minutes on a modern workstation, reducing slew overheads by a factor of 5 compared to random ordering. We also provide a heuristic method that can return a near-optimal solution at significantly reduced computational cost. As a case study, we explore our algorithm's suitability to automatic schedule generation for Doppler planet searches.Comment: 21 pages, 5 figure

Периферическая невропатия при рассеянном склерозе. Клинические и электрофизиологические аспекты

Nicolae Testemitanu State Medical and Pharmaceutical University, Institute of Neurology and Neurosurgery, Medical and Sanitary Department of the Information and Security ServiceLa un lot de 50 de pacienţi, cu scleroză multiplă clinic şi imagistic definită, au fost studiate manifestările clinice şi electrofiziologice de afectare a fibrelor nervilor periferici. Deşi semnele clinice de neuropatie la aceşti pacienţi se determină doar ocazional, examenul de stimulodetecţie frecvent (în 28% din cazuri) pune în evidenţă existenţa subclinică a unei neuropatii periferice, manifestate prin diminuarea vitezei de conducere, majorarea latenţei distale şi latenţei răspunsurilor tardive (undei-F). Procesul patologic în cadrul sclerozei multiple nu se limitează la demielinizarea fibrelor sistemului nervos central, dar se extinde şi la radiculele nervoase, fibrele motorii şi sensorii ale nervilor periferici.В группе из 50 больных рассеянным склерозом были исследованы клинические и электрофизиологические проявления поражения волокон периферических нервов. Несмотря на то, что у этих больных клинические признаки невропатии определяются лищь изредка, при исследовании проведения нервных импульсов выявлено частое (в 28% случаях) доклиническое проявление периферической невропатии, проявляющейся снижением скорости проведения, увеличением дистальной латентности и латентности поздних ответов (F-волны). Патологический процесс при рассеянном склерозе не ограничивается демиелинизацией волокон центральной нервной системы, он распространяется и на нервные корешки спинного мозга и на двигательные и чувствительные волокна периферических нервов

Ipigrix (ipidacrin) in the complex treatment of patients with idiopathic axonal polyneuropathy

Department of Neurology, Institute of Neurology and Neurosurgery, Nicolae Testemitsanu State University of Medicine and Pharmacy, Chisinau, the Republic of MoldovaBackground: Peripheral neuropathy is a frequent nosologic unit, its prevalence being estimated as 2-8% of the population. Polyneuropathy treatment is especially difficult in the axonal forms cases. To study the effectiveness of the medicines acting on the pathogenetic evolution of the polyneuropathy is very important. The objectives of the study have been to assess the efficiency of ipigrix (ipidacrin) with regard to the clinical state of the patients with idiopathic axonal polyneuropathy (IAP) and to determine its influence on electromyographic indices. Material and methods: 2 groups of 30 patients with IAP have been examined in an open controlled trial. In the complex treatment of the patients of group A ipigrix (ipidacrin) has been added – 15 mg (1.5% solution – 1.0 ml) intramuscularly for 20 days. The patients of group B have received a standard treatment. Results: After the course of the treatment in the both studied groups the improvement has been recorded both in clinic and electromyographic indices. But the statistically significant changes have been observed only in group A – in the patients who have additionally received ipidacrin. These changes have been related to the significant increase of the nerve conduction velocity in motor and sensory fibers of peripheral nerves. Conclusions: ipigrix (ipidacrin) positively influences and improves the clinical outcomes and electromyographic indices in the patients with IAP. It can be successfully used in the complex treatment of axonal polyneuropathies of other determined etiologies (diabetic, alcoholic, uremic, etc.)

Robot-Assisted Prostate Brachytherapy

Abstract: In contemporary brachytherapy procedures, needle placement at the desired target is challenging due to a variety of reasons. A robot-assisted brachytherapy system can potentially improve needle placement and seed delivery, resulting in enhanced therapeutic delivery. In this paper we present a 16 DOF (degrees-of-freedom) robotic system (9DOF positioning module and 7DOF surgery module) developed and fabricated for prostate brachytherapy. Strategies to reduce needle deflection and target movement were incorporated after extensive experimental validation. Provisions for needle motion and force feedback were included into the system for improving robot control and seed delivery. Preliminary experimental results reveal that the prototype system is sufficiently accurate in placing brachytherapy needles

Mind your step: the effects of mobile phone use on gaze behavior in stair climbing

Stair walking is a hazardous activity and a common cause of fatal and non-fatal falls. Previous studies have assessed the role of eye movements in stair walking by asking people to repeatedly go up and down stairs in quiet and controlled conditions, while the role of peripheral vision was examined by giving participants specific fixation instructions or working memory tasks. We here extend this research to stair walking in a natural environment with other people present on the stairs and a now common secondary task: Using one's mobile phone. Results show that using the mobile phone strongly draws one's attention away from the stairs, but that the distribution of gaze locations away from the phone is little influenced by using one's phone. Phone use also increased the time needed to walk the stairs, but handrail use remained low. These results indicate that limited foveal vision suffices for adequate stair walking in normal environments, but that mobile phone use has a strong influence on attention, which may pose problems when unexpected obstacles are encountered

Quantum information processes in protein microtubules of brain neurons

We study biologically ‘orchestrated’ coherent quantum processes in collections of protein microtubules of brain neurons, which correlate with, and regulate, neuronal synaptic and membrane activity. In this situation the continuous Schrodinger evolution of each such process terminates in accordance with the specific Diosi-Penrose (DP) scheme of ‘objective reduction’ (‘OR’) of the quantum state. This orchestrated OR activity (‘Orch OR’) is taken to result in moments of conscious awareness and/or choice. We analyze Orch OR in light of advances and developments in quantum physics, computational neuroscience and quantum biology. Much attention is also devoted to the ‘beat frequencies’ of faster microtubule vibrations as a possible source of the observed electroencephalographic (‘EEG’) correlates of consciousness