Improving PV Module Efficiency Through Cooling

The Solarbacks researched and designed a variety of cooling methods that could be used to improve the efficiency of photovoltaics. These cooling methods can be separated into two categories: active and passive methods. The active cooling method of hydraulic cooling and the passive cooling methods of heat sinks (fins), optical coatings, thermosyphons, phase change materials, and thermoelectric generators were all taken into consideration as potential cooling methods. Passive cooling methods were preferred because the use of electricity required for the cooling mechanism would reduce the net electricity and subsequent profit from the panels. Two variations of hydraulic cooling were researched: water spraying and the use of closed channels along the back of the panel. Both water spraying and closed channels along the back of the panel could effectively cool down photovoltaics, but the energy required to pump the necessary amount of water would exceed the additional power generated from cooling. Both variations would also require significant capital cost and would be difficult to scale up. Two passive methods – thermosyphons and phase change materials – were researched but not tested as a final design. Thermosyphons use heat from the panel to boil a working fluid, increased buoyancy moves the fluid upwards where excess heat is released into the environment, condensing the fluid back into a liquid. This starts the process over again. Thermosyphons have been proven to work effectively for concentrated photovoltaic systems; however, the layout of typical solar farms is not conducive for thermosyphons if they utilize a solar tracking system. Chosen phase change materials would have a melting point that is within the operating range of the heated solar panel, and would cool the panel through conductive heat transfer from the back of the panel to the phase change material. When put in thermal contact with the panel, the panel’s temperature would not exceed the melting temperature of the material until all of it had melted. This method was disregarded because once the material had melted, the panel would no longer be cooled. Additional passive methods were researched and tested. Ideal optical coatings reflect any solar irradiance that is not used by the panel to produce electricity, however, the coatings researched and tested produced minimal cooling. The coating Solarbacks tested was a thin sheet of mylar (saran wrap). The average cooling produced by the saran wrap was about 2.4oC. However, most of this cooling is thought to be a result of a thermosyphon effect because the saran wrap was elevated off the surface of the panel rather than being directly attached. This elevation likely induced forced convection with the outside air to cool the panel. Fins as a heat sink work by increasing the surface area that heat can be dissipated from. One of the biggest disadvantages to fins is that their efficacy is strongly dependent on ambient conditions. The fins tested by Solarbacks were 1” tall, spaced 1” from each other, and placed on a 1/8” aluminum sheet and attached to the photovoltaic panel using a thermal mastic. The approximate cost of materials per panel would be around $28 when materials are purchased in bulk for a 1/32” thickness extruded fin. Testing showed that fins could cool the panel 14oC during peak temperatures and increase power output by about 5.52Thermal electric generators (TEGs) use electrically dissimilar semiconductors to produce an electric current. When put in thermal contact with the back of the panel, the generator would use any excess heat to produce electricity. The heat TEGs use to produce electricity could help cool the panel to some degree, but their main contribution is the additional electricity they generate. This additional electricity would outweigh the losses due to heating and increase the profitability of each solar panel. If the back of a panel was covered with TEGs and a 20oC temperature difference was maintained for 8 hr. a day in New Mexico, the TEGs would produce an additional 0.778 kWh/day. The biggest disadvantage to using TEGs is the capital cost. Using typical TEG dimensions (40mm*40mm), 536 of them would need to be bought per panel with each TEG costing about$2.92. Larger TEGs could be produced to fit to back of each panel and could reduce this capital cost significantly. Overall, TEGs with fins provides the greatest amount of panel cooling and additional power production. There is an average of a 12.1°C temperature difference along a panel with this solution installed. Using manufacturer data, an estimated 135W can be produced from the TEGs at a 20°C temperature differential along the TEGs. However, when payout for this method is considered, it would take nearly 31 years. Purchasing additional panels that produce the same amount of power as the TEGs would have a payout period of less than 6 years. TEGs with fins at their current cost is not an economic alternative to purchasing more panels despite its cooling and power production capabilities

Peripheral nerve injury increases glutamate-evoked calcium mobilization in adult spinal cord neurons

BACKGROUND: Central sensitization in the spinal cord requires glutamate receptor activation and intracellular Ca2+ mobilization. We used Fura-2 AM bulk loading of mouse slices together with wide-field Ca2+ imaging to measure glutamate-evoked increases in extracellular Ca2+ to test the hypotheses that: 1. Exogenous application of glutamate causes Ca2+ mobilization in a preponderance of dorsal horn neurons within spinal cord slices taken from adult mice; 2. Glutamate-evoked Ca2+ mobilization is associated with spontaneous and/or evoked action potentials; 3. Glutamate acts at glutamate receptor subtypes to evoked Ca2+ transients; and 4. The magnitude of glutamate-evoked Ca2+ responses increases in the setting of peripheral neuropathic pain. RESULTS: Bath-applied glutamate robustly increased [Ca2+]i in 14.4 ± 2.6 cells per dorsal horn within a 440 x 330 um field-of-view, with an average time-to-peak of 27 s and decay of 112 s. Repeated application produced sequential responses of similar magnitude, indicating the absence of sensitization, desensitization or tachyphylaxis. Ca2+ transients were glutamate concentration-dependent with a Kd = 0.64 mM. Ca2+ responses predominantly occurred on neurons since: 1) Over 95% of glutamate-responsive cells did not label with the astrocyte marker, SR-101; 2) 62% of fura-2 AM loaded cells exhibited spontaneous action potentials; 3) 75% of cells that responded to locally-applied glutamate with a rise in [Ca2+]i also showed a significant increase in AP frequency upon a subsequent glutamate exposure; 4) In experiments using simultaneous on-cell recordings and Ca2+ imaging, glutamate elicited a Ca2+ response and an increase in AP frequency. AMPA/kainate (CNQX)- and AMPA (GYKI 52466)-selective receptor antagonists significantly attenuated glutamate-evoked increases in [Ca2+]i, while NMDA (AP-5), kainate (UBP-301) and class I mGluRs (AIDA) did not. Compared to sham controls, peripheral nerve injury significantly decreased mechanical paw withdrawal threshold and increased glutamate-evoked Ca2+ signals. CONCLUSIONS: Bulk-loading fura-2 AM into spinal cord slices is a successful means for determining glutamate-evoked Ca2+ mobilization in naïve adult dorsal horn neurons. AMPA receptors mediate the majority of these responses. Peripheral neuropathic injury potentiates Ca2+ signaling in dorsal horn

Improving PV Module Efficiency Through Cooling

The Solarbacks researched and designed a variety of cooling methods that could be used to improve the efficiency of photovoltaics. These cooling methods can be separated into two categories: active and passive methods. The active cooling method of hydraulic cooling and the passive cooling methods of heat sinks (fins), optical coatings, thermosyphons, phase change materials, and thermoelectric generators were all taken into consideration as potential cooling methods. Passive cooling methods were preferred because the use of electricity required for the cooling mechanism would reduce the net electricity and subsequent profit from the panels. Two variations of hydraulic cooling were researched: water spraying and the use of closed channels along the back of the panel. Both water spraying and closed channels along the back of the panel could effectively cool down photovoltaics, but the energy required to pump the necessary amount of water would exceed the additional power generated from cooling. Both variations would also require significant capital cost and would be difficult to scale up. Two passive methods – thermosyphons and phase change materials – were researched but not tested as a final design. Thermosyphons use heat from the panel to boil a working fluid, increased buoyancy moves the fluid upwards where excess heat is released into the environment, condensing the fluid back into a liquid. This starts the process over again. Thermosyphons have been proven to work effectively for concentrated photovoltaic systems; however, the layout of typical solar farms is not conducive for thermosyphons if they utilize a solar tracking system. Chosen phase change materials would have a melting point that is within the operating range of the heated solar panel, and would cool the panel through conductive heat transfer from the back of the panel to the phase change material. When put in thermal contact with the panel, the panel’s temperature would not exceed the melting temperature of the material until all of it had melted. This method was disregarded because once the material had melted, the panel would no longer be cooled. Additional passive methods were researched and tested. Ideal optical coatings reflect any solar irradiance that is not used by the panel to produce electricity, however, the coatings researched and tested produced minimal cooling. The coating Solarbacks tested was a thin sheet of mylar (saran wrap). The average cooling produced by the saran wrap was about 2.4oC. However, most of this cooling is thought to be a result of a thermosyphon effect because the saran wrap was elevated off the surface of the panel rather than being directly attached. This elevation likely induced forced convection with the outside air to cool the panel. Fins as a heat sink work by increasing the surface area that heat can be dissipated from. One of the biggest disadvantages to fins is that their efficacy is strongly dependent on ambient conditions. The fins tested by Solarbacks were 1” tall, spaced 1” from each other, and placed on a 1/8” aluminum sheet and attached to the photovoltaic panel using a thermal mastic. The approximate cost of materials per panel would be around $28 when materials are purchased in bulk for a 1/32” thickness extruded fin. Testing showed that fins could cool the panel 14oC during peak temperatures and increase power output by about 5.52Thermal electric generators (TEGs) use electrically dissimilar semiconductors to produce an electric current. When put in thermal contact with the back of the panel, the generator would use any excess heat to produce electricity. The heat TEGs use to produce electricity could help cool the panel to some degree, but their main contribution is the additional electricity they generate. This additional electricity would outweigh the losses due to heating and increase the profitability of each solar panel. If the back of a panel was covered with TEGs and a 20oC temperature difference was maintained for 8 hr. a day in New Mexico, the TEGs would produce an additional 0.778 kWh/day. The biggest disadvantage to using TEGs is the capital cost. Using typical TEG dimensions (40mm*40mm), 536 of them would need to be bought per panel with each TEG costing about$2.92. Larger TEGs could be produced to fit to back of each panel and could reduce this capital cost significantly. Overall, TEGs with fins provides the greatest amount of panel cooling and additional power production. There is an average of a 12.1°C temperature difference along a panel with this solution installed. Using manufacturer data, an estimated 135W can be produced from the TEGs at a 20°C temperature differential along the TEGs. However, when payout for this method is considered, it would take nearly 31 years. Purchasing additional panels that produce the same amount of power as the TEGs would have a payout period of less than 6 years. TEGs with fins at their current cost is not an economic alternative to purchasing more panels despite its cooling and power production capabilities

Fast, large volume, GPU enabled simulations for the Ly-alpha forest: power spectrum forecasts for baryon acoustic oscillation experiments

High redshift measurements of the baryonic acoustic oscillation scale (BAO) from large Ly-alpha forest surveys represent the next frontier of dark energy studies. As part of this effort, efficient simulations of the BAO signature from the Ly-alpha forest will be required. We construct a model for producing fast, large volume simulations of the Ly-alpha forest for this purpose. Utilising a calibrated semi-analytic approach, we are able to run very large simulations in 1 Gpc^3 volumes which fully resolve the Jeans scale in less than a day on a desktop PC using a GPU enabled version of our code. The Ly-alpha forest spectra extracted from our semi-analytical simulations are in excellent agreement with those obtained from a fully hydrodynamical reference simulation. Furthermore, we find our simulated data are in broad agreement with observational measurements of the flux probability distribution and 1D flux power spectrum. We are able to correctly recover the input BAO scale from the 3D Ly-alpha flux power spectrum measured from our simulated data, and estimate that a BOSS-like 10^4 deg^2 survey with ~15 background sources per square degree and a signal-to-noise of ~5 per pixel should achieve a measurement of the BAO scale to within ~1.4 per cent. We also use our simulations to provide simple power-law expressions for estimating the fractional error on the BAO scale on varying the signal-to-noise and the number density of background sources. The speed and flexibility of our approach is well suited for exploring parameter space and the impact of observational and astrophysical systematics on the recovery of the BAO signature from forthcoming large scale spectroscopic surveys.Comment: 16 pages, 11 figures, accepted to MNRA

Speckle tracking as a method to measure hemidiaphragm excursion

Introduction: Diaphragm excursion measured via ultrasound may be an important imaging outcome measure of respiratory function. We developed a new method for measuring diaphragm movement and compared it to the more traditional M‐mode method. Methods: Ultrasound images of the right and left hemidiaphragms were collected to compare speckle tracking and M‐mode measurements of diaphragm excursion. Speckle tracking was performed using EchoInsight (Epsilon Imaging, Ann Arbor, Michigan). Results: Six healthy subjects without a history of pulmonary diseases were included in this proof‐of‐concept study. Speckle tracking of the diaphragm is technically possible. Unlike M‐mode, speckle tracking carries the advantage of reliable visualization and measurement of the left hemidiaphragm. Conclusions: Speckle tracking accounted for diaphragm movement simultaneously in the cephalocaudad and mediolateral directions, unlike M‐mode, which is 1‐dimensional. Diaphragm speckle tracking may represent a novel, more robust method for measuring diaphragm excursion, especially for the left hemidiaphragm. Muscle Nerve 55: 125–127, 2017Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135149/1/mus25380.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135149/2/mus25380_am.pd

Concert recording 2018-02-22

[Track 1]. Full tilt / Anthony DiLorenzo -- [Track 2]. Great Lakes octet. I. Shimmering under the sunlight [Track 3]. II. Frozen under winter skies [Track 4]. III. Storm-tossed [Track 5]. IV. Spring horizon / Eric Ewazen -- [Track 6]. Wayfaring stranger / arranged by Chris Woods -- [Track 7]. On a hymnsong of Philip Bliss / David Holsinger translated by William Harbinson -- [Track 8]. Allegretto from Sinfonietta / Leoš Lanáček arranged by Cory Mixdorf -- [Track 9]. October / Eric Whitacre arranged by Christopher E. Hass -- [Track 10]. Fanfare for paratroopers / Paul Creston arranged by Philip Jameson

Young Adults with Cleft Lip and Palate: Are They Receiving Team Services?

It is widely acknowledged that a team approach is preferred practice and contributes to optimizing the surgical, dental, speech and psychosocial outcomes for individuals with CLP. Young adulthood often marks the transition from child-centered interdisciplinary care to adult-centered care. There is a paucity in literature relating to the transition of care for young adults with CLP. The purpose of this survey research is therefore to explore the CLP team practices regarding young adults with CLP

Stimulus Motion Propels Traveling Waves in Binocular Rivalry

State transitions in the nervous system often take shape as traveling waves, whereby one neural state is replaced by another across space in a wave-like manner. In visual perception, transitions between the two mutually exclusive percepts that alternate when the two eyes view conflicting stimuli (binocular rivalry) may also take shape as traveling waves. The properties of these waves point to a neural substrate of binocular rivalry alternations that have the hallmark signs of lower cortical areas. In a series of experiments, we show a potent interaction between traveling waves in binocular rivalry and stimulus motion. The course of the traveling wave is biased in the motion direction of the suppressed stimulus that gains dominance by means of the wave-like transition. Thus, stimulus motion may propel the traveling wave across the stimulus to the extent that the stimulus motion dictates the traveling wave's direction completely. Using a computational model, we show that a speed-dependent asymmetry in lateral inhibitory connections between retinotopically organized and motion-sensitive neurons can explain our results. We argue that such a change in suppressive connections may play a vital role in the resolution of dynamic occlusion situations

GAA repeat expansion mutation mouse models of Friedreich ataxia exhibit oxidative stress leading to progressive neuronal and cardiac pathology

Friedreich ataxia (FRDA) is a neurodegenerative disorder caused by an unstable GAA repeat expansion mutation within intron 1 of the FXN gene. However, the origins of the GAA repeat expansion, its unstable dynamics within different cells and tissues, and its effects on frataxin expression are not yet completely understood. Therefore, we have chosen to generate representative FRDA mouse models by using the human FXN GAA repeat expansion itself as the genetically modified mutation. We have previously reported the establishment of two lines of human FXN YAC transgenic mice that contain unstable GAA repeat expansions within the appropriate genomic context. We now describe the generation of FRDA mouse models by crossbreeding of both lines of human FXN YAC transgenic mice with heterozygous Fxn knockout mice. The resultant FRDA mice that express only human-derived frataxin show comparatively reduced levels of frataxin mRNA and protein expression, decreased aconitase activity, and oxidative stress, leading to progressive neurodegenerative and cardiac pathological phenotypes. Coordination deficits are present, as measured by accelerating rotarod analysis, together with a progressive decrease in locomotor activity and increase in weight. Large vacuoles are detected within neurons of the dorsal root ganglia (DRG), predominantly within the lumbar regions in 6-month-old mice, but spreading to the cervical regions after 1 year of age. Secondary demyelination of large axons is also detected within the lumbar roots of older mice. Lipofuscin deposition is increased in both DRG neurons and cardiomyocytes, and iron deposition is detected in cardiomyocytes after 1 year of age. These mice represent the first GAA repeat expansion-based FRDA mouse models that exhibit progressive FRDA-like pathology and thus will be of use in testing potential therapeutic strategies, particularly GAA repeat-based strategies. © 2006 Elsevier Inc. All rights reserved