Comparison of Randomized Multifocal Mapping and Temporal Phase Mapping of Visual Cortex for Clinical Use

fMRI is becoming an important clinical tool for planning and guidance of surgery to treat brain tumors, arteriovenous malformations, and epileptic foci. For visual cortex mapping, the most popular paradigm by far is temporal phase mapping, although random multifocal stimulation paradigms have drawn increased attention due to their ability to identify complex response fields and their random properties. In this study we directly compared temporal phase and multifocal vision mapping paradigms with respect to clinically relevant factors including: time efficiency, mapping completeness, and the effects of noise. Randomized, multifocal mapping accurately decomposed the response of single voxels to multiple stimulus locations and made correct retinotopic assignments as noise levels increased despite decreasing sensitivity. Also, multifocal mapping became less efficient as the number of stimulus segments (locations) increased from 13 to 25 to 49 and when duty cycle was increased from 25% to 50%. Phase mapping, on the other hand, activated more extrastriate visual areas, was more time efficient in achieving statistically significant responses, and had better sensitivity as noise increased, though with an increase in systematic retinotopic mis-assignments. Overall, temporal phase mapping is likely to be a better choice for routine clinical applications though random multifocal mapping may offer some unique advantages for selected applications

Two-dimensional localized structures in harmonically forced oscillatory systems

Two-dimensional spatially localized structures in the complex Ginzburg–Landau equation with 1:1 resonance are studied near the simultaneous presence of a steady front between two spatially homogeneous equilibria and a supercritical Turing bifurcation on one of them. The bifurcation structures of steady circular fronts and localized target patterns are computed in the Turing-stable and Turing-unstable regimes. In particular, localized target patterns grow along the solution branch via ring insertion at the core in a process reminiscent of defect-mediated snaking in one spatial dimension. Stability of axisymmetric solutions on these branches with respect to axisymmetric and nonaxisymmetric perturbations is determined, and parameter regimes with stable axisymmetric oscillons are identified. Direct numerical simulations reveal novel depinning dynamics of localized target patterns in the radial direction, and of circular and planar localized hexagonal patterns in the fully two-dimensional system

Energy use and CO2 emissions of sweet potato production in Tarlac, Philippines

In this study, the energy use and carbon dioxide (CO2) emission of sweet potato production in Tarlac, Philippines were evaluated. Data were collected from 180 farmers using structured survey questionnaires and face to face interview. Accordingly, the total input and output energy of sweet potato production was 29326.78 and 53885.90 MJ ha-1, respectively. Chemical fertilizers and diesel fuel provided the biggest portion of the total energy consumption in sweet potato production. The energy use efficiency, specific energy and energy productivity was 1.84, 1.95 MJ kg-1 and 0.51 kg MJ-1. Indirect and non-renewable forms of energy dominated the share of the total input energy. The total GHG emission of sweet potato production was 1432.18 kg CO2eq ha-1 (0.095 kg CO2 kg-1). Non-renewable sources of energy such as diesel fuel and chemical fertilizers were the main contributors of GHGs emission at 53.35% and 43.36%, respectively. The use of renewable sources of input energy can lead to lesser GHG emission, more sustainable and environment-friendly agricultural production system for sweet potato. Energy management should be considered as vital strategy for resource conservation, climate protection and to promote sustainable agriculture for sweet potato production

Demyelination and axonal preservation in a transgenic mouse model of Pelizaeus-Merzbacher disease

It is widely thought that demyelination contributes to the degeneration of axons and, in combination with acute inflammatory injury, is responsible for progressive axonal loss and persistent clinical disability in inflammatory demyelinating disease. In this study we sought to characterize the relationship between demyelination, inflammation and axonal transport changes using a Plp1-transgenic mouse model of Pelizaeus-Merzbacher disease. In the optic pathway of this non-immune mediated model of demyelination, myelin loss progresses from the optic nerve head towards the brain, over a period of months. Axonal transport is functionally perturbed at sites associated with local inflammation and 'damaged' myelin. Surprisingly, where demyelination is complete, naked axons appear well preserved despite a significant reduction of axonal transport. Our results suggest that neuroinflammation and/or oligodendrocyte dysfunction are more deleterious for axonal health than demyelination per se, at least in the short ter

Environmental performance of farmer-level corn production systems in the Philippines

Four corn production systems at farmer-level of operation were evaluated. Environmental performance such as energy use, energy efficiency, greenhouse gas emission (GHG) and carbon efficiency were determined. Data were collected from 60 corn producing farmers using survey questionnaires and face to face interview. The input energy to produce an output energy of 69,714.06 and 73,029.60 MJ/ha for sun drying and mechanical drying, respectively, were 22,346.27, 31, 469.75, 22, 399.05 and 31,522.53 MJ/ha for systems 1 (manual harvesting and sun drying), 2 (manual harvesting and mechanical drying), 3 (mechanical harvesting and sun drying) and 4 (mechanical harvesting and mechanical drying), respectively.  The highest energy input was observed for system 4 followed by system 2 because of the additional energy input of kerosene fuel during mechanical drying.  Non-renewable and indirect forms of energy had contributed most to the total input energy in all corn production systems.  In all systems evaluated, chemical fertilizer had the highest share in energy input followed by diesel fuel. Lower GHG emissions were measured for system 1 and 3 at 1276.5 and 1309.60 kg CO2eq per ha, respectively than system 2 and 4 at 2101.9 and 2135.0 kg CO2eq per ha due to additional non-renewable energy input like kerosene during mechanical drying.  A kilogram of dried corn grain emitted 0.27 to 28 kg CO2eq for system 1 and 3 and increased further to 0.42 to 0.43 kg CO2eq for systems 2 and 4.  The net carbon sequestered for systems 1, 2, 3 and 4 was 1785.98, 1662.36, 1776.94 and 1653.33 kg C/ha, respectively. The highest carbon efficiency ratio was observed for system 1 at 6.13 followed by system 3 at 5.98 due to non-utilization of fossil fuel during drying.  Generally, all corn production systems evaluated did not emit carbon beyond the carbon produced and sequestered in corn itself as indicated by their positive net carbon ratio

Amnion cells engineering: A new perspective in fetal membrane healing after intrauterine surgery?

In this study we aimed to set up an in vitro culture of the rabbit amnion in order to support in vivo fetal membrane healing capacity following fetoscopy. Fetal membranes were collected from a mid- gestational rabbit, and cultured on collagen support material for 14 days. 34 rabbits at 22 - 23 days gestational age ( GA) underwent fetoscopy. The entry site was randomly allocated to 4 closure technique study groups: group I, human amnion membrane ( n = 23); group II, collagen foil ( n = 16); group III, collagen plug ( n = 19), and group IV, collagen plug with cultured amnion cells ( n = 19). In all groups membrane access sites were additionally sealed with fibrin sealant, and the myometrium was closed with sutures. Fetal survival, amnion membrane integrity, and the presence of amniotic fluid were evaluated at 30 days GA. Cultures showed good survival in the collagen support material. Increased cellularity, survival and proliferations were observed. The amnion at the access site resealed in 58 - 64% of cases in groups II - IV, but none of the tested techniques was significantly better than the other. Histological examination indirectly revealed the anatomic repair of the membranes, since no entrapment of the membranes could be demonstrated in the myometrial wound. Copyright (c) 2006 S. Karger AG, Basel