Fluid percussion injury transiently increases then decreases brain oxygen consumption in the rat

The oxygen consumption (VO2 microL/h/mg) of sham and of traumatized rat brains within 30 min and 6 h after a lateral fluid percussion injury (FPI) was measured with the Cartesian microrespirometer. Brain slices were cut at the plain of injury and site-specific 20-60-microg cores of tissue were transferred to the microrespirometer. In sham brains, the cortical VO2 (CVO2) was 13.78+/-0.64 and the hippocampal VO2 (HPVO2) was 11.20+/-0.58 microL/h/mg (p<0.05). Within 30 min of the injury, the respective values of 16.89+/-0.55 and 14.91+/-0.06 were significantly increased (p<0.05). The combined VO2 (CVO2, HPVO2) of 12.49+/-0.06 microL/h/mg in shams was significantly less than the combined VO2 of 15.90+/-0.59 microL/h/mg at 30 min post FPI (p<0.001). The maximal CVO2 of 19.49+/-1.10 microL/h/mg and the maximal HPVO2 of 15.98+/-0.99 microL/h/mg were both obtained from the ipsilateral side of the injury. Whereas the contralateral cortical value for injured brains was not significantly different from that of the shams, both ipsilateral and contralateral hippocampal values were significantly greater than that of the shams in response to injury (p<0.05). By 6 h postinjury, the combined VO2 had dropped to 10.01+/-0.84 microL/h/mg but was not significantly lower than the sham values. The data indicate that normal CVO2 is greater than normal HPVO2. The FPI produces significant increases in both CVO2 and HPVO2. Also, while the immediate increase in CVO2 appears to be injury-site dependent, that is, regional, the increase in HPVO2 appears to be global.

Synthesis and Redox and Photophysical Properties of Benzodifuran-Spiropyran Ensembles

Two benzodifuran (BDF)-coupled spiropyran (SP) systems and their BDF reference compounds were obtained in good yields through HuisgenMeldalSharpless click chemistry and then subjected to investigation of their electrochemical and photophysical properties. In both SP and merocyanine (MC) forms of the coupled molecules, the BDF-based emission is quenched to around 1 of the quantum yield of emission from the BDF reference compounds. Based on electrochemical data, this quenching is attributed to oxidative electron-transfer quenching. Irradiation at 366nm results in ring opening to the MC forms of the BDF-coupled SP compounds and the SP reference compound with a quantum efficiency of about 50. The rate constants for the thermal ring closing are approximately 3.4x103s1. However, in the photostationary states the MC fractions of the coupled molecules are substantially lower than that of the reference SP compound, attributed to the observed acceleration of the ring-closing reaction upon irradiation. As irradiation at 366nm invariably also excites higher-energy transitions of the BDF units in the coupled compounds, the ring-opening reaction is accelerated relative to the SP reference, which results in lower MC fractions in the photostationary state. Reversible photochromism of these BDF-coupled SP compounds renders them promising in the field of molecular switches.

Fast Update of Conditional Simulation Ensembles

Gaussian random field (GRF) conditional simulation is a key ingredient in many spatial statistics problems for computing Monte-Carlo estimators and quantifying uncertainties on non-linear functionals of GRFs conditional on data. Conditional simulations are known to often be computer intensive, especially when appealing to matrix decomposition approaches with a large number of simulation points. This work studies settings where conditioning observations are assimilated batch sequentially, with one point or a batch of points at each stage. Assuming that conditional simulations have been performed at a previous stage, the goal is to take advantage of already available sample paths and by-products to produce updated conditional simulations at mini- mal cost. Explicit formulae are provided, which allow updating an ensemble of sample paths conditioned on n ≥ 0 observations to an ensemble conditioned on n + q observations, for arbitrary q ≥ 1. Compared to direct approaches, the proposed formulae proveto substantially reduce computational complexity. Moreover, these formulae explicitly exhibit how the q new observations are updating the old sample paths. Detailed complexity calculations highlighting the benefits of this approach with respect to state-of-the-art algorithms are provided and are complemented by numerical experiments.

Analyses of maternal and child mortality rates of five West African countries: Cote d'Ivoire, Guinea, Liberia, Senegal, Sierra Leone

After traveling to a small country in West Africa last summer, I became interested in learning more about the maternal, infant, and child death rates of that particular region of the continent. For the purposes of this paper I limited the number of countries that would be included in this research to five: Cote d'Ivoire, Guinea, Liberia, Senegal, and Sierra Leone. There are three hypotheses that were considered when conducting the research for this paper. The first was that there is no difference in the under five mortality rates for Cote d'Ivoire, Guinea, Liberia, Senegal, and Sierra Leone. The second hypothesis was that there is no difference in the female literacy rates for Cote d'Ivoire, Guinea, Liberia, Senegal, and Sierra Leone. The final hypothesis was that there is no difference in the male literacy rates for Cote d'Ivoire, Guinea, Liberia, Senegal, and Sierra Leone. The data used were collected from publicly available sources that include the CIA World Factbook, the WHO website, the UNICEF website, the Penn World Data table, and the World Bank website. The p-values that were calculated for all three hypotheses were found to be very significant, and all three of the null hypotheses were rejected. ^

A time-slice study in Heinrich Stadial 1 and Mid Holocene sediment cores off northern Senegal

Sediment dynamics in limnic, fluvial and marine environments can be assessed by granulometric and rock-magnetic methodologies. While classical grain-size analysis by sieving or settling mainly bears information on composition and transport, the magnetic mineral assemblages reflect to a larger extent the petrology and weathering conditions in the sediment source areas. Here, we combine both methods to investigate Late Quaternary marine sediments from five cores along a transect across the continental slope off Senegal. This region near the modern summer Intertropical Convergence Zone is particularly sensitive to climate change and receives sediments from several aeolian, fluvial and marine sources. From each of the investigated five GeoB sediment cores (494-2956 m water depth) two time slices were processed which represent contrasting climatic conditions: the arid Heinrich Stadial 1 (~ 15 kyr BP) and the humid Mid Holocene (~ 6 kyr BP). Each sediment sample was split into 16 grain-size fractions ranging from 1.6 to 500 µm. Concentration and grain-size indicative magnetic parameters (susceptibility, SIRM, HIRM, ARM and ARM/IRM) were determined at room temperature for each of these fractions. The joint consideration of whole sediment and magnetic mineral grain-size distributions allows to address several important issues: (i) distinction of two aeolian sediment fractions, one carried by the north-easterly trade winds (40-63 µm) and the other by the overlying easterly Harmattan wind (10-20 µm) as well as a fluvial fraction assigned to the Senegal River (< 10 µm); (ii) identification of three terrigenous sediment source areas: southern Sahara and Sahel dust (low fine-grained magnetite amounts and a comparatively high haematite content), dust from Senegalese coastal dunes (intermediate fine-grained magnetite and haematite contents) and soils from the upper reaches of the Senegal River (high fine-grained magnetite content); (iii) detection of partial diagenetic dissolution of fine magnetite particles as a function of organic input and shore distance; (iv) analysis of magnetic properties of marine carbonates dominating the grain-size fractions 63-500 µm.