SOI N-Channel Field Effect Transistors, CHT-NMOS80, for Extreme Temperatures

Extreme temperatures, both hot and cold, are anticipated in many of NASA space exploration missions as well as in terrestrial applications. One can seldom find electronics that are capable of operation under both regimes. Even for operation under one (hot or cold) temperature extreme, some thermal controls need to be introduced to provide appropriate ambient temperatures so that spacecraft on-board or field on-site electronic systems work properly. The inclusion of these controls, which comprise of heating elements and radiators along with their associated structures, adds to the complexity in the design of the system, increases cost and weight, and affects overall reliability. Thus, it would be highly desirable and very beneficial to eliminate these thermal measures in order to simplify system's design, improve efficiency, reduce development and launch costs, and improve reliability. These requirements can only be met through the development of electronic parts that are designed for proper and efficient operation under extreme temperature conditions. Silicon-on-insulator (SOI) based devices are finding more use in harsh environments due to the benefits that their inherent design offers in terms of reduced leakage currents, less power consumption, faster switching speeds, good radiation tolerance, and extreme temperature operability. Little is known, however, about their performance at cryogenic temperatures and under wide thermal swings. The objective of this work was to evaluate the performance of a new commercial-off-the-shelf (COTS) SOI parts over an extended temperature range and to determine the effects of thermal cycling on their performance. The results will establish a baseline on the suitability of such devices for use in space exploration missions under extreme temperatures, and will aid mission planners and circuit designers in the proper selection of electronic parts and circuits. The electronic part investigated in this work comprised of a CHT-NMOS80 high temperature N-channel MOSFET (metal-oxide semiconductor field-effect transistor) device that was manufactured by CISSOID. This high voltage, medium-power transistor is fabricated using SOI processes and is designed for extreme wide temperature applications such as geothermal well logging, aerospace and avionics, and automotive industry. It has a high DC current capability and is specified for operation in the temperature range of -55 C to +225

What is the potential of oligodendrocyte progenitor cells to successfully treat human spinal cord injury?

<p>Abstract</p> <p>Background</p> <p>Spinal cord injury is a serious and debilitating condition, affecting millions of people worldwide. Long seen as a permanent injury, recent advances in stem cell research have brought closer the possibility of repairing the spinal cord. One such approach involves injecting oligodendrocyte progenitor cells, derived from human embryonic stem cells, into the injured spinal cord in the hope that they will initiate repair. A phase I clinical trial of this therapy was started in mid 2010 and is currently underway.</p> <p>Discussion</p> <p>The theory underlying this approach is that these myelinating progenitors will phenotypically replace myelin lost during injury whilst helping to promote a repair environment in the lesion. However, the importance of demyelination in the pathogenesis of human spinal cord injury is a contentious issue and a body of literature suggests that it is only a minor factor in the overall injury process.</p> <p>Summary</p> <p>This review examines the validity of the theory underpinning the on-going clinical trial as well as analysing published data from animal models and finally discussing issues surrounding safety and purity in order to assess the potential of this approach to successfully treat acute human spinal cord injury.</p

Retinoid X receptor gamma signaling accelerates CNS remyelination

The molecular basis of CNS myelin regeneration (remyelination) is poorly understood. We generated a comprehensive transcriptional profile of the separate stages of spontaneous remyelination that follow focal demyelination in the rat CNS and found that transcripts that encode the retinoid acid receptor RXR-γ were differentially expressed during remyelination. Cells of the oligodendrocyte lineage expressed RXR-γ in rat tissues that were undergoing remyelination and in active and remyelinated multiple sclerosis lesions. Knockdown of RXR-γ by RNA interference or RXR-specific antagonists severely inhibited oligodendrocyte differentiation in culture. In mice that lacked RXR-γ, adult oligodendrocyte precursor cells efficiently repopulated lesions after demyelination, but showed delayed differentiation into mature oligodendrocytes. Administration of the RXR agonist 9-cis-retinoic acid to demyelinated cerebellar slice cultures and to aged rats after demyelination caused an increase in remyelinated axons. Our results indicate that RXR-γ is a positive regulator of endogenous oligodendrocyte precursor cell differentiation and remyelination and might be a pharmacological target for regenerative therapy in the CNS

Analysis of water resources in Safford, Arizona.

Safford Valley, Arizona obtains irrigation water from a combination of surface water and ground water. Sometimes during the summer both surface and ground water are not enough for crop demands. Ground water is very high in dissolved solids. Every year approximately 200,000 tons of dissolved solids are deposited on the crop lands in the irrigation water. The total annual irrigation water requirement in the valley, as estimated by the Blaney-Criddle method, is 241,000 acre-feet. Diverted water plus pumpage is 210,000 acre-ft. per year. Total net annual water use in the valley, as estimated by a water budget equation, is 107,000 acre-ft. Diverted plus pumped water less the net volume of water • represents water lost to seepage from the valley. Historical data records were used to generate data by a lag-one Markov process using statistical parameters from five different periods. The generated data were then used to estimate storage capacity of a proposed reservoir by flow-mass curve analysis. The 100-year flood was estimated by flood frquency analysis using three different frequency distributions. The extreme flood, as plotted on Gumbel, arithmetic and log-normal probability paper was found to be 78,000, 75,000 and 126,000 cubic feet per second (cfs), respectively. Three water management alternatives were suggested for the purpose of improving water use in the basin. The alternative that was more efficient in irrigation practices was recommended.hydrology collectio

Phenological characteristics of different Poplar species at Yassoj Experimental Station

In order to collect and study the morphological- phenological characteristics and ecological requirements of different poplars, 40 most successful clones were selected from Selection Nursery and transferred into Mother Individual collection by 5*5 and 4*4 m intervals for open and closed crown species, respectively, using five seedlings for each planting line. The collection is located in western Iran, near Yasooj in Kohgiluye and Buyerahmad province. The studied growth characteristics contained of diameter and height which recorded at the end of growth period. The phenological phenomena consisted of were flower, leaf, seed development and leaf fall. Furthermore, daily maximum and minimum temperature data was recorded all over the growth period. The results showed that the poplar biotic activity usually starts at March and ends at November. The phenological phenomena at different poplar species and clones started in different dates due to variation in species and clones genetic characteristics and climate condition which varied from few days to few weeks. Beginning of phenological phenomena of a species is usually correlated to air temperature (maximum, minimum and average) at beginning of growth period, whereas its end is often correlated to photoperiodism and minimum air temperature. Leaf discolor and fall date at different poplar species varied from 6th September to 6th November due to shorter day time and cooler air temperature. The species P. alba and P. euramericana started their phenological activities earlier than the other species and the clones of P. alba and P. deltoides had longest biotic activities. The clones of P. alba were more sensetive to forest, whereas the clones of P. euramericana and P. deltoides were very sensetive to pests, particularly to beetle xylophagus (Melanophila sp.). About 70% of P. euramericana clones were complete died due to damage caused by this pest

Generation of three induced Pluripotent Stem Cell lines from individuals with Hypomyelination with Atrophy of Basal Ganglia and Cerebellum caused by a c.745G>A (p.D249N) autosomal dominant mutation in TUBB4A

Mutations in tubulin alpha 4a (TUBB4A) result in a spectrum of leukodystrophies, including Hypomyelination with atrophy of basal ganglia and cerebellum (H-ABC), resulting from a recurring mutation p.Asp249Asn (TUBB4AD249N). H-ABC presents with dystonia, motor and cognitive impairment and pathological features of hypomyelination and loss of cerebellar and striatal neurons. We have generated three induced pluripotent stem cell (iPSC) lines from fibroblast and peripheral blood mononuclear cells (PBMCs) of individuals with TUBB4AD249N mutation. The iPSCs were assessed to confirm a normal karyotype, pluripotency, and trilineage differentiation potential. The iPSCs will allow for disease modeling, understanding mechanisms and testing of therapeutic targets

Cx43 hemichannels contribute to astrocyte-mediated toxicity in sporadic and familial ALS

Connexin 43 (Cx43) gap junctions and hemichannels mediate astrocyte intercellular communication in the central nervous system under normal conditions and contribute to astrocyte-mediated neurotoxicity in amyotrophic lateral sclerosis (ALS). Here, we show that astrocyte-specific knockout of Cx43 in a mouse model of ALS slows disease progression both spatially and temporally, provides motor neuron (MN) protection, and improves survival. In addition, Cx43 expression is up-regulated in human postmortem tissue and cerebrospinal fluid from ALS patients. Using human induced pluripotent stem cell–derived astrocytes (hiPSC-A) from both familial and sporadic ALS, we establish that Cx43 is up-regulated and that Cx43-hemichannels are enriched at the astrocyte membrane. We also demonstrate that the pharmacological blockade of Cx43-hemichannels in ALS astrocytes using GAP 19, a mimetic peptide blocker, and tonabersat, a clinically tested small molecule, provides neuroprotection of hiPSC-MN and reduces ALS astrocyte-mediated neuronal hyperexcitability. Extending the in vitro application of tonabersat with chronic administration to SOD1G93A mice results in MN protection with a reduction in reactive astrocytosis and microgliosis. Taking these data together, our studies identify Cx43 hemichannels as conduits of astrocyte-mediated disease progression and a pharmacological target for disease-modifying ALS therapies