223 research outputs found

    Free choice activates a decision circuit between frontal and parietal cortex

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    We often face alternatives that we are free to choose between. Planning movements to select an alternative involves several areas in frontal and parietal cortex that are anatomically connected into long-range circuits. These areas must coordinate their activity to select a common movement goal, but how neural circuits make decisions remains poorly understood. Here we simultaneously record from the dorsal premotor area (PMd) in frontal cortex and the parietal reach region (PRR) in parietal cortex to investigate neural circuit mechanisms for decision making. We find that correlations in spike and local field potential (LFP) activity between these areas are greater when monkeys are freely making choices than when they are following instructions. We propose that a decision circuit featuring a sub-population of cells in frontal and parietal cortex may exchange information to coordinate activity between these areas. Cells participating in this decision circuit may influence movement choices by providing a common bias to the selection of movement goals

    Comparative efficacy of topical tetraVisc versus lidocaine gel in cataract surgery

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    <p>Abstract</p> <p>Background</p> <p>To compare the clinical efficacy of lidocaine 2% with tetracaine 0.5% for cataract surgery.</p> <p>Methods</p> <p>In a randomized, multi-surgeon, controlled clinical trial,122 consecutive cataract cases eligible for topical anesthesia, were randomly assigned to receive lidocaine 2% gel (1 ml) or tetracaine solution 0.5% (TetraVisc, 0.5 ml) before clear corneal phacoemulsification. Main outcome measure was visual analog scale (0 to 10), which was used to measure intra-operative pain. Secondary outcome measures included patients' discomfort due to tissue manipulation and surgeon graded patients' cooperation. Duration of surgery and intra-operative complications were also recorded.</p> <p>Results</p> <p>The mean age in TetraVisc (TV) group was 70.4 years and in the lidocaine gel group (LG) it was 70.6 years (p = 0.89). Patient reported mean intra-operative pain scores by visual analog scale were 0.70 ± 0.31 in TV group and 1.8 ± 0.4 in LG group (<it>P </it>< 0.001). Mean patient cooperation was also marginally better in the TV group (8.3 ± 0.3) compared to LG group (8.4 ± 0.6) (P = 0.25). 96% of patients in TV group showed intra-operative corneal clarity compared to 91% in LG group. TV group had less (1 out of 61 patients, 1.6%) intra-operative complications than LG group (3 out of 61 patients, 4.8%). No anesthesia related complications were noted in either group</p> <p>Conclusion</p> <p>Topical TetraVisc solution was superior to lidocaine 2% gel for pain control in patients undergoing clear corneal phacoemulsification. Lidocaine 2% gel is similar to TetraVisc in patient comfort and surgeon satisfaction.</p> <p>Trial Registration</p> <p><b>Clinical trials number</b>: ISRCTN78374774</p

    An assessment of the eye care workforce in Enugu State, south-eastern Nigeria

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    <p>Abstract</p> <p>Background</p> <p>The availability and distribution of an appropriate eye care workforce are fundamental to reaching the goals of "VISION 2020: The right to sight", the global initiative for the elimination of avoidable blindness launched jointly by the World Health Organization and the International Agency for the Prevention of Blindness with an international membership of nongovernmental organizations, professional associations, eye care institutions and corporations. Periodic evaluation of these parameters is important in the journey towards achieving these goals. The objectives of the study were to determine the availability and distribution of human resources for eye care delivery in Enugu Urban, south-eastern Nigeria.</p> <p>Methods</p> <p>The study was designed as a cross-sectional descriptive survey, the setting for which was all public and privately owned eye care facilities in Enugu Urban, Enugu State, south-eastern Nigeria, in October 2006. The health map of Enugu Urban and the hospital register of the Public Health Department of the Enugu State Ministry of Health were used to identify the eye health care facilities in Enugu Urban. A structured, pretested, researcher-administered questionnaire was used to capture data on cadre and distribution of the eye care personnel in these facilities.</p> <p>Relevant population data were obtained from the Enugu Regional Office of the National Population Commission. Descriptive statistical analysis was used to generate percentages and proportions. Eye care personnel-to-population ratios were calculated and compared to World Health Organization recommendations.</p> <p>Results</p> <p>Out of Enugu State's population of three million, Enugu Urban accounts for 22%. The population of Enugu Urban is distributed between the three-component Local Government Areas comprising Enugu North (31%), Enugu South (30%) and Enugu East (39%). There are 45 eye care facilities (public: 31 (69%); private: 14 (31%)) employing 252 eye care workers (public: 226 (90%); private: 26 (10%)) aged 18 to 63 (mean = 36.1 years, SD = 2 years) comprising males (36: 14%) and females (216: 86%), giving a male-to-female sex ratio of 1:6. The available eye care workforce is unevenly distributed between Enugu North (128: 51%), Enugu South (65: 26%) and Enugu East (59: 23%) Local Government Areas.</p> <p>Conclusion</p> <p>Using broad and crude World Health Organization standards for minimum provider-to-population ratios, there is a sufficient eye care workforce in Enugu Urban. However, the maldistribution of the workforce creates a major barrier to uptake of eye care services. Policy modifications could reverse this maldistribution.</p

    Redistribution of Actin during Assembly and Reassembly of the Contractile Ring in Grasshopper Spermatocytes

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    Cytokinesis in animal cells requires the assembly of an actomyosin contractile ring to cleave the cell. The ring is highly dynamic; it assembles and disassembles during each cell cleavage, resulting in the recurrent redistribution of actin. To investigate this process in grasshopper spermatocytes, we mechanically manipulated the spindle to induce actin redistribution into ectopic contractile rings, around reassembled lateral spindles. To enhance visualization of actin, we folded the spindle at its equator to convert the remnants of the partially assembled ring into a concentrated source of actin. Filaments from the disintegrating ring aligned along reorganizing spindle microtubules, suggesting that their incorporation into the new ring was mediated by microtubules. We tracked incorporation by speckling actin filaments with Qdots and/or labeling them with Alexa 488-phalloidin. The pattern of movement implied that actin was transported along spindle microtubules, before entering the ring. By double-labeling dividing cells, we imaged actin filaments moving along microtubules near the contractile ring. Together, our findings indicate that in one mechanism of actin redistribution, actin filaments are transported along spindle microtubule tracks in a plus-end–directed fashion. After reaching the spindle midzone, the filaments could be transported laterally to the ring. Notably, actin filaments undergo a dramatic trajectory change as they enter the ring, implying the existence of a pulling force. Two other mechanisms of actin redistribution, cortical flow and de novo assembly, are also present in grasshopper, suggesting that actin converges at the nascent contractile ring from diffuse sources within the cytoplasm and cortex, mediated by spindle microtubules

    Characteristics of Different Systems for the Solar Drying of Crops

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    Solar dryers are used to enable the preservation of agricultural crops, food processing industries for dehydration of fruits and vegetables, fish and meat drying, dairy industries for production of milk powder, seasoning of wood and timber, textile industries for drying of textile materials. The fundamental concepts and contexts of their use to dry crops is discussed in the chapter. It is shown that solar drying is the outcome of complex interactions particular between the intensity and duration of solar energy, the prevailing ambient relative humidity and temperature, the characteristics of the particular crop and its pre-preparation and the design and operation of the solar dryer
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