Formation of an r8-Dominant Si Material.

The rhombohedral phase of Si (r8-Si), a promising semiconducting material, is formed by indentation together with the body-centered cubic phase (bc8-Si). Using a novel sample preparation method, x-ray diffraction is used to determine the relative volume of these phases in indented Si and allow observation of a distorted unit cell along the direction of indentation loading. Theoretical calculations together with these observations suggest the indent contains an intrinsic compression of ∼4 GPa that stabilizes the r8 phase.

Identification of a novel, fast-acting GABAergic antidepressant.

Current pharmacotherapies for depression exhibit slow onset, side effects and limited efficacy. Therefore, identification of novel fast-onset antidepressants is desirable. GLO1 is a ubiquitous cellular enzyme responsible for the detoxification of the glycolytic byproduct methylglyoxal (MG). We have previously shown that MG is a competitive partial agonist at GABA-A receptors. We examined the effects of genetic and pharmacological inhibition of GLO1 in two antidepressant assay models: the tail suspension test (TST) and the forced swim test (FST). We also examined the effects of GLO1 inhibition in three models of antidepressant onset: the chronic FST (cFST), chronic mild stress (CMS) paradigm and olfactory bulbectomy (OBX). Genetic knockdown of Glo1 or pharmacological inhibition using two structurally distinct GLO1 inhibitors (S-bromobenzylglutathione cyclopentyl diester (pBBG) or methyl-gerfelin (MeGFN)) reduced immobility in the TST and acute FST. Both GLO1 inhibitors also reduced immobility in the cFST after 5 days of treatment. In contrast, the serotonin reuptake inhibitor fluoxetine (FLX) reduced immobility after 14, but not 5 days of treatment. Furthermore, 5 days of treatment with either GLO1 inhibitor blocked the depression-like effects induced by CMS on the FST and coat state, and attenuated OBX-induced locomotor hyperactivity. Finally, 5 days of treatment with a GLO1 inhibitor (pBBG), but not FLX, induced molecular markers of the antidepressant response including brain-derived neurotrophic factor (BDNF) induction and increased phosphorylated cyclic-AMP response-binding protein (pCREB) to CREB ratio in the hippocampus and medial prefrontal cortex (mPFC). Our findings indicate that GLO1 inhibitors may provide a novel and fast-acting pharmacotherapy for depression.

The structure of CO2 hydrate between 0.7 and 1.0 GPa.

A deuterated sample of CO2 structure I (sI) clathrate hydrate (CO2·8.3 D2O) has been formed and neutron diffraction experiments up to 1.0 GPa at 240 K were performed. The sI CO2 hydrate transformed at 0.7 GPa into the high pressure phase that had been observed previously by Hirai et al. [J. Phys. Chem. 133, 124511 (2010)] and Bollengier et al. [Geochim. Cosmochim. Acta 119, 322 (2013)], but which had not been structurally identified. The current neutron diffraction data were successfully fitted to a filled ice structure with CO2 molecules filling the water channels. This CO2+water system has also been investigated using classical molecular dynamics and density functional ab initio methods to provide additional characterization of the high pressure structure. Both models indicate the water network adapts a MH-III "like" filled ice structure with considerable disorder of the orientations of the CO2 molecule. Furthermore, the disorder appears to be a direct result of the level of proton disorder in the water network. In contrast to the conclusions of Bollengier et al., our neutron diffraction data show that the filled ice phase can be recovered to ambient pressure (0.1 MPa) at 96 K, and recrystallization to sI hydrate occurs upon subsequent heating to 150 K, possibly by first forming low density amorphous ice. Unlike other clathrate hydrate systems, which transform from the sI or sII structure to the hexagonal structure (sH) then to the filled ice structure, CO2 hydrate transforms directly from the sI form to the filled ice structure.

Interaction between cognitive and motor cortico-basal ganglia loops during decision making: a computational study.

In a previous modeling study, Leblois et al. (2006) demonstrated an action selection mechanism in cortico-basal ganglia loops based on competition between the positive feedback, direct pathway through the striatum and the negative feedback, hyperdirect pathway through the subthalamic nucleus. The present study investigates how multiple level action selection could be performed by the basal ganglia. To do this, the model is extended in a manner consistent with known anatomy and electrophysiology in three main areas. First, two-level decision making has been incorporated, with a cognitive level selecting based on cue shape and a motor level selecting based on cue position. We show that the decision made at the cognitive level can be used to bias the decision at the motor level. We then demonstrate that, for accurate transmission of information between decision-making levels, low excitability of striatal projection neurons is necessary, a generally observed electrophysiological finding. Second, instead of providing a biasing signal between cue choices as an external input to the network, we show that the action selection process can be driven by reasonable levels of noise. Finally, we incorporate dopamine modulated learning at corticostriatal synapses. As learning progresses, the action selection becomes based on learned visual cue values and is not interfered with by the noise that was necessary before learning.

Design, calibration, and performance of a uniaxial pressure cell for neutron scattering studies of quantum magnetism.

We provide an overview of a pressure cell designed to apply uniaxial pressure to single crystals for the study, by neutron scattering techniques, of strongly correlated magnetic systems and, in particular, quantum magnets. A detailed overview of the pressure cell components, their requirements, and links to the scientific and technical specifications are presented. The pressure cell is able to accommodate a 200 mm3 single crystal that can be pressurized up to 2 GPa at cryogenic temperatures. The pressure cell is consistent with the requirements of inelastic neutron scattering and, importantly, neutron polarization analysis. A particular strength of the uniaxial pressure cell is the highly uniform and low background for a wide scattering angle of 360° horizontally and ±20° vertically. We show the performance of the uniaxial pressure cell using a relevant neutron scattering instrument, the polarized diffuse scattering instrument, D7. The experiments confirm that the cell complies with the scientific and technical requirements. This uniaxial pressure cell will provide a useful additional tool in the sample environment suite available for the study of quantum magnetism.

Cage occupancies in the high pressure structure H methane hydrate: a neutron diffraction study.

A neutron diffraction study was performed on the CD(4) : D(2)O structure H clathrate hydrate to refine its CD(4) fractional cage occupancies. Samples of ice VII and hexagonal (sH) methane hydrate were produced in a Paris-Edinburgh press and in situ neutron diffraction data collected. The data were analyzed with the Rietveld method and yielded average cage occupancies of 3.1 CD(4) molecules in the large 20-hedron (5(12)6(8)) cages of the hydrate unit cell. Each of the pentagonal dodecahedron (5(12)) and 12-hedron (4(3)5(6)6(3)) cages in the sH unit cell are occupied with on average 0.89 and 0.90 CD(4) molecules, respectively. This experiment avoided the co-formation of Ice VI and sH hydrate, this mixture is more difficult to analyze due to the proclivity of ice VI to form highly textured crystals, and overlapping Bragg peaks of the two phases. These results provide essential information for the refinement of intermolecular potential parameters for the water-methane hydrophobic interaction in clathrate hydrates and related dense structures.

The distorted close-packed crystal structure of methane A.

We have determined the full crystal structure of the high-pressure phase methane A. X-ray single-crystal diffraction data were used to determine the carbon-atom arrangement, and neutron powder diffraction data from a deuterated sample allowed the deuterium atoms to be located. It was then possible to refine all the hydrogen positions from the single-crystal x-ray data. The structure has 21 molecules in a rhombohedral unit cell, and is quite strongly distorted from the cubic close-packed structure of methane I, although some structural similarities remain. Full knowledge of this structure is important for modeling of methane at higher pressures, including in relation to the mineralogy of the outer solar system. We discuss interesting structural parallels with the carbon tetrahalides.

Calculation of one-electron redox potentials revisited. Is it possible to calculate accurate potentials with density functional methods?

Density Functional calculations have been performed to calculate the one-electron oxidation potential for ferrocene and the redox couples for a series of small transition metal compounds of the first-, second-, and third-row elements. The solvation effects are incorporated via a self-consistent reaction field (SCRF), using the polarized continuum model (PCM). From our study of seven different density functionals combined with three different basis sets for ferrocene, we find that no density functional method can reproduce the redox trends from experiment when referencing our results to the experimental absolute standard hydrogen electrode (SHE) potential. In addition, including additional necessary assumptions such as solvation effects does not lead to any conclusion regarding the appropriate functional. However, we propose that if one references their transition metal compounds results to the calculated absolute half-cell potential of ferrocene, they can circumvent the additional assumptions necessary to predict a redox couple. Upon employing this method on several organometallic and inorganic complexes, we obtained very good correlation between calculated and experimental values (R(2) = 0.97), making it possible to predict trends with a high level of confidence. The hybrid functional B3LYP systematically underestimates the redox potential; however, the linear correlation between DFT and experiment is good (R(2) = 0.96) when including a baseline shift. This protocol is a powerful tool that allows theoretical chemists to predict the redox potential in solution of several transition metal complexes a priori and aids in the rational design of redox-active catalysts.

Magnetic and structural changes in LaCo0.9Mn0.1O3 at high pressure.

The structural and magnetic properties of LaCo0.9Mn0.1O3 have been studied as a function of pressure by neutron powder diffraction and DC magnetometry. The material is confirmed to exhibit rhombohedral R [Formula: see text] c symmetry between ambient pressure and 6 GPa. We have determined the bulk modulus B 0 of the sample using a second-order Birch-Murnaghan equation of state which yielded: B 0 = 140(9) GPa and V [Formula: see text]. We report a non-linear increase of the Curie temperature T C from an ambient pressure value of 224.7 K to ∼236 K at a pressure of 4 GPa. Finally, we confirm the glassy-like nature of the magnetism in LaCo0.9Mn0.1O3, which is maintained throughout the pressure range explored.

A suite-level review of the neutron powder diffraction instruments at Oak Ridge National Laboratory.

The suite of neutron powder diffractometers at Oak Ridge National Laboratory (ORNL) utilizes the distinct characteristics of the Spallation Neutron Source and High Flux Isotope Reactor to enable the measurements of powder samples over an unparalleled regime at a single laboratory. Full refinements over large Q ranges, total scattering methods, fast measurements under changing conditions, and a wide array of sample environments are available. This article provides a brief overview of each powder instrument at ORNL and details the complementarity across the suite. Future directions for the powder suite, including upgrades and new instruments, are also discussed.

Future directions in high-pressure neutron diffraction.

The ability to manipulate structure and properties using pressure has been well known for many centuries. Diffraction provides the unique ability to observe these structural changes in fine detail on lengthscales spanning atomic to nanometre dimensions. Amongst the broad suite of diffraction tools available today, neutrons provide unique capabilities of fundamental importance. However, to date, the growth of neutron diffraction under extremes of pressure has been limited by the weakness of available sources. In recent years, substantial government investments have led to the construction of a new generation of neutron sources while existing facilities have been revitalized by upgrades. The timely convergence of these bright facilities with new pressure-cell technologies suggests that the field of high-pressure (HP) neutron science is on the cusp of substantial growth. Here, the history of HP neutron research is examined with the hope of gleaning an accurate prediction of where some of these revolutionary capabilities will lead in the near future. In particular, a dramatic expansion of current pressure-temperature range is likely, with corresponding increased scope for extreme-conditions science with neutron diffraction. This increase in coverage will be matched with improvements in data quality. Furthermore, we can also expect broad new capabilities beyond diffraction, including in neutron imaging, small angle scattering and inelastic spectroscopy.

Nerve fiber degeneration following a single experimental cerebral concussion in the rat.

This study has demonstrated widespread nerve fiber degeneration (nfd) following experimental cerebral concussion (ECC) in the rat by use of the Fink-Heimer modification of the Nauta--Gygax silver staining method for impregnation of degenerating axons. Beginning approximately 1 mm rostral to the optic chiasm and progressing caudally to the level of the cervical spinal cord and sampling at 600 micrometers intervals, 60 of the most prominent neuronal structures showing nfd have been identified and tend to be associated with 3 sites of injury; the coup, the contrecoup and the craniocervical junction. The duration of ECC was compared to the extent of nfd observed.

When does metoclopramide facilitate transpyloric intubation?

Postpyloric feeding probably reduces the incidence of tracheobronchial aspiration and improves feeding tolerance. However, duodenal intubation is often unsuccessful in critically ill patients due to gastric atony. Metoclopramide improves gastric emptying. In a pilot study, 12 adult patients were administered 10 to 20 mg of intravenous metoclopramide after weighted nasal feeding tubes had failed to spontaneously pass distal to the pylorus. In no patient did metoclopramide induce transpyloric passage of the tube. A randomized prospective study involving 10 adult patients was conducted to examine the effect of preinsertion intravenous metoclopramide on transpyloric intubation. All patients had failed to achieve spontaneous duodenal intubation. Five patients received 20 mg of metoclopramide 10 min prior to nasal insertion of a weighed feeding tube. Five control patients received no premedication. Four metoclopramide patients achieved duodenal intubation immediately. In none of the control patients did transpyloric intubation occur (p = 0.048). Metoclopramide, administered after nasogastric intubation, is ineffective in promoting transpyloric advancement of feeding tubes. There is a significant increase in transpyloric intubation when metoclopramide is administered prior to tube insertion.

Effects of erythropoietin on strength and functional status of patients on hemodialysis.

The strength, endurance, and functional status of 15 anemic (HCT 21.2 +/- 4.6) hemodialysis patients was quantified prior to the administration of erythropoietin (epoetin) and after the anemia was partially corrected (HCT 35.4 +/- 2.3). Subjects showed significant increases in strength, measured isometrically (p < .01) and isokinetically (p < .01 at four of five speeds). They also demonstrated improved endurance and rated their functional ability higher. Anemia contributes to significant debilitation in hemodialysis patients and, when reversed with epoetin therapy, results in significantly improved muscle function and endurance.

Congenital esotropia.

The prognosis for congenital esotropia remains guarded. Monofixation syndrome currently is the best widely reported result following surgery. The reoperation rate in congenital esotropia (including reoperations for horizontal misalignment, dissociated vertical deulation, and inferior oblique overaction) also is high, approaching 50%. The role of very early surgical intervention needs to be examined further and could result in dramatic improvement in the long-term outcomes associated with congenital esotropia.

Clinical decision making by experienced and inexperienced pediatric physical therapists for children with diplegic cerebral palsy.

BACKGROUND AND PURPOSE: This qualitative study was designed to explore, identify, and describe clinical decision-making processes used by pediatric physical therapists. SUBJECTS: Clinical decision-making processes of three experienced therapists and three inexperienced therapists were assessed as they worked with 18 children with diplegia. METHODS: Retrospective think-aloud procedures were used to elicit verbalizations, which were transcribed, coded, and analyzed. RESULTS: Four characteristics of clinical decision making were identified: (1) Movement scripts provided insights into the clinical application of cognitive schemata based on previous experiences, (2) procedural changes occurred rapidly during within-session decision making, (3) psychosocial sensitivity was important for positive interaction during therapy, and (4) self-monitoring appeared to be pivotal in making clinical decisions as therapists self-assessed their practice. Contrasting data illustrated similarities and differences of experienced and inexperienced clinicians. CONCLUSION AND DISCUSSION: Findings are generally consistent with existing clinical decision-making literature and provide important information for physical therapy practice, research, and education.

Exogenous PGF(2)alpha enhanced GnRH-induced LH release in postpartum cows.

This study evaluated the effect of exogenous PGF(2)alpha on circulating LH concentrations in postpartum multiparous (n = 32) and primiparous (n = 46) Brahman cows. The cows were randomly allotted within parity and calving date to receive 0, 1, 2 or 3 mg im PGF(2)alpha (alfaprostol)/100 kg body weight (BW), with or without GnRH on Day 30 after calving. Blood samples were collected at weekly intervals from calving through treatment. Serum progesterone concentrations were determined using RIA procedures to assure that only anestrous cows were treated. Sterile marker bulls were maintained with cows on Coastal bermudagrass pastures until the first estrus was detected. Multiparous cows had a shorter (P < 0.05) interval from calving to estrus than did primiparous cows. Serum LH was affected by time (P < 0.0001), PGF(2)alpha dose (P < 0.0002), GnRH (P < 0.0001), parity by PGF(2)alpha dose (P < 0.0003), PGF(2)alpha dose by GnRH (P < 0.0009), parity by GnRH (P < 0.0008), and by parity by PGF(2)alpha dose by GnRH (P < 0.0005). Multiparous cows not receiving GnRH had higher mean serum LH (P < 0.02), LH peak pulse height (P < 0.03), and area under the LH release curve (P < 0.03) compared with primiparous cows. The number of LH pulses/6 h was greater (P < 0.06) in multiparous than primiparous cows, and was greater (P < 0.02) in multiparous cows receiving 3 mg/100 kg BW than in cows receiving 2 mg/100 kg BW, but not in the controls or in cows receiving 1 mg/100 kg BW. Exogenous GnRH resulted in increased (P < 0.0001) serum LH concentrations in all cows, and LH was enhanced (P < 0.0009) by simultaneous treatment with PGF(2)alpha. Primiparous cows had a greater response (P < 0.0005) to PGF(2)alpha and GnRH compared with multiparous cows. Pituitary release of LH in response to GnRH was enhanced by simultaneous exposure to PGF(2)alpha in Day 30 postpartum cows.

Response to environmental temperatures in Brahman calves during the first compared to the second day after birth.

Brahman calves (n = 28) were used to evaluate the effect of environmental temperature during the 1st or 2nd d after birth. Calves were removed from their dams within 30 min of birth (newborn; D0) before suckling or at 20 h of age and fasted for 4 h before treatment (day-old; D1). Calves were placed in either a warm (W; 25 degrees C) or a cold (C; 5 degrees C) environment for 2 h and either maintained in or transferred to, respectively, W for 22 h. Blood samples were collected via jugular catheters at 15-min intervals beginning at initial placement in W or C through 3 h and at 4, 5, 6, 8, 10, 12, 14, 18, and 24 h. Rectal temperature (Tr) was recorded with each sample. Following the 60-min and 12-h samples, each calf was administered 1 liter of colostrum from its dam. Serum or plasma was analyzed for glucose, lactate, plasma urea nitrogen, triglycerides, nonesterified fatty acids, insulin, cortisol, triiodothyronine (T3), and thyroxine (T4). Rectal temperature of D0C calves was lower (P less than .05) than that of other calves from 75 min through 3 h. Insulin, lactate, T3, and plasma urea nitrogen concentrations were not different among all calves. Higher (P less than .01) cortisol and T4 concentrations were observed in D0 than in D1 calves. Cortisol (P less than .008) and nonesterified fatty acid (P less than .05) levels were greater in C than in W calves. All D0 calves had lower (P less than .0001) glucose concentrations than D1 calves until the 12-h feeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of exogenous glucose or colostrum on body temperature, plasma glucose, and serum insulin in cold-stressed, newborn Brahman calves.

The effects of ambient temperature and source of exogenous energy (glucose or colostrum) on the ability of newborn Brahman calves to maintain rectal temperature (RT) were determined. All calves were removed from dams within 30 min of birth, before suckling. Calves were catheterized and placed in either a warm (25 degrees C) or cold (5 degrees C) environment for 150 min and given either colostrum or glucose. This resulted in four groups (warm colostrum, n = 7; cold colostrum, n = 7; warm glucose, n = 6; cold glucose, n = 6). Blood samples and RT were obtained at 15-min intervals during warm or cold through 150 min, when calves were removed from cold, and at 180, 240, and 300 min. After 60 min, each calf was given either 1 L of colostrum (38 degrees C) from its dam or glucose (38 degrees C) infusion of 750 mg/kg BW. Plasma glucose concentrations were determined by enzymatic techniques and serum insulin concentrations by RIA. Calves exposed to cold or warm air temperatures had similar declines in rectal temperature from 0 to 60 min. Colostrum-fed, cold calves had a greater (P less than .07) decrease in RT than did colostrum-fed, warm calves from 75 through 150 min; glucose-infused warm and cold calves had intermediate decreases in RT. Plasma glucose increased (P less than .0001) in glucose-infused compared with colostrum-fed calves at 75 min, but glucose-infused calves had lower (P less than .02) glucose levels from 180 to 300 min. Higher (P less than .05) glucose concentrations

Evaluation of luteolysis and estrous synchronization by a prostaglandin analog (Luprostiol) in Brahman cows and heifers.

A trial was conducted to evaluate the ability of a prostaglandin analog, Luprostiol (LP), to synchronize estrus in Brahman cows and heifers. Animals were injected with either 0, 3.75, 7.5, 15 or 30 mg LP or 500 micrograms cloprostenol (CLP) on d 8 or 9 after estrus (d 0). All concentrations of LP (greater than 0 mg) and CLP caused luteolysis in cows and heifers, as indicated by a decline (P less than .01) in serum progesterone concentration after injection. Animals receiving 0 or 3.75 mg LP had a longer (P less than .04) interval to estrus after injection than did animals in other treatment groups. The proportion of animals exhibiting estrus by 120 h after injection was influenced by dose of LP (P less than .0001; 0, 3.75 mg less than 7.5, 15 and 30 mg and CLP) but not by age. Cows had a lower (P less than .01) progesterone concentration than heifers on d 10, 11 and 12 after LP-induced estrus. Progesterone concentration was lowest (P less than .01) on d 10, 11 and 12 after LP-induced estrus in cows given 15 mg LP or CLP. First-service conception rate was similar between cows and heifers, but it was lower (P less than .01) in animals given 15 or 30 mg LP. Both estrogen and LH concentrations were decreased (P less than .01) at the time of estrus by the 15 and 30 mg of LP. Luprostiol can cause luteolysis and estrous synchrony in Brahman cattle.(ABSTRACT TRUNCATED AT 250 WORDS)