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Downward Direction (downward + direction)
Selected AbstractsMedial septal modulation of the ascending brainstem hippocampal synchronizing pathways in the anesthetized ratHIPPOCAMPUS, Issue 1 2006Jesse Jackson Abstract Independent and combined electrical stimulation pairings of the medial septum (MS), posterior hypothalamus (PH), and reticular pontine oralis (RPO) of the brainstem were performed in the acute urethane anesthetized rat, while recording field activity from electrodes in either the stratum oriens or stratum moleculare of the hippocampal formation. Theta frequency and power were measured during independent stimulation of each nuclei and during combined stimulation using three pairings: (1) MS,PH (2) MS,RPO and (3) PH,RPO. Each pairing consisted of parameters known to elicit theta of a high frequency for one nucleus, and parameters known to elicit a low frequency for the second nucleus. This methodology allowed us to observe whether one nucleus preferentially modulated theta activity in the hippocampus in terms of frequency and power. The MS was observed to reset theta frequency in both the upward and downward direction when stimulated in combination with either the PH (Experiment 1) or the RPO (Experiment 2). In Experiment 3 (PH,RPO), the structure receiving the higher intensity stimulation had the predominate effect on theta frequency. With MS stimulation combinations, the power of the elicited theta activity was found to increase over the independent stimulation in some cases during Experiment 1. Likewise, in Experiment 2, the combined stimulation produced a power that in most cases was significantly greater than that measured during the independent stimulations. This effect was not observed with PH and RPO stimulation combinations. The combined stimulation of the PH and RPO yielded a power similar to the independent PH stimulations. The findings support the following conclusions: (1) the major theta generating activity of the ascending brainstem synchronizing pathways involves projections from the RPO to the PH, relayed through the MS, to the hippocampal formation; and (2) that the MS directly controls theta amplitude and secondarily translates the level of ascending brainstem activity into the appropriate frequency of hippocampal theta. © 2005 Wiley-Liss, Inc. [source] Bearing capacity of two interfering footingsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 3 2008Jyant Kumar Abstract By using an upper bound limit analysis in conjunction with finite elements and linear programming, the ultimate bearing capacity of two interfering rough strip footings, resting on a cohesionless medium, was computed. Along all the interfaces of the chosen triangular elements, velocity discontinuities were employed. The plastic strains were incorporated using an associated flow rule. For different clear spacing (S) between the two footings, the efficiency factor (,,) was determined, where ,, is defined as the ratio of the failure load for a strip footing of given width in the presence of the other footing to that of a single isolated strip footing having the same width. The value of ,, at S/B = 0 becomes equal to 2.0, and the maximum ,, occurs at S/B = ,Scr/B. For S/B,Scr/B, the ultimate failure load for a footing becomes almost half that of an isolated footing having width (2B + S), and the soil mass below and in between the two footings deforms mainly in the downward direction. In contrast, for S/B>Scr/B, ground heave was noticed along both the sides of the footing. As compared to the available theories, the analysis provides generally lower values of ,, for S/B>Scr/B. Copyright © 2007 John Wiley & Sons, Ltd. [source] RETORTABILITY of THIN-WALLED ALUMINUM CONTAINERS PRESSURIZED WITH ADDED LIQUID NITROGEN (LN2)JOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2003G.B. AWUAH ABSTRACT Studies were conducted to investigate the effect of initial container pressure on heat penetration parameters using flexible aluminum containers. A pilot scale liquid nitrogen dispenser, regulated to discharge a fine stream of liquid nitrogen (LN2), provided approximately 10 to 15 psi pressure within the container prior to end-over-end processing in a computer-controlled retort using water immersion with 32 psi over pressure. Thermal process parameters including the heating rate index (fh), lag factor (jh), the cumulative lethality (Fo), cook-value (Co) and the overall heat transfer coefficient (Uo) were examined in relation to retort temperature (241,261F), rpm (0,15 rpm) and product initial temperature (54,121F) using 5% w/w bentonite suspension with or without liquid nitrogen. Generally, containers with added liquid nitrogen had no impact on evaluated data compared to their counterparts without LN2 under similar experimental conditions. Estimated overall heat transfer coefficient (Uo) compared favorably with published data, while the Co/Fo ratio decreased with increasing temperatures as expected. Product cold spot location migrated in either upward or downward direction depending on the mode of heat transfer. Although added LN2 generally had no limiting effect on both heat transfer and heat penetration data, processing aluminum containers with high initial pressure at high retort temperatures could create excessively high internal pressure that could compromise container seam integrity. [source] Assessing giftedness with the WISC-III and the SB-IVPSYCHOLOGY IN THE SCHOOLS, Issue 5 2002Michael Simpson The Wechsler Intelligence Scale for Children,Third Edition (WISC-III) and the Stanford-Binet Intelligence Scale,Fourth Edition (SB-IV), were administered to 20 gifted children and 20 non-gifted children to examine the extent of the difference in IQ scores obtained on the two tests and whether order effects were present. Results show that the SB-IV Composite Score was significantly higher than the WISC-III Full Scale IQ for both groups. However, for the gifted group, unlike the non-gifted group, this difference achieved significance only when the SB-IV was administered first. When either IQ test was administered to the gifted students for the first time, without the confound of a learning influence, there was no significant difference in mean scores. However, when both tests were administered, it was found that the SB-IV influenced the WISC-III Full Scale IQ in a downward direction whereas the WISC-III influenced the SB-IV Composite Score in an upward direction. © 2002 Wiley Periodicals, Inc. [source] Mathematical model for mixing index in gas,solid fluidized bed: an analysisASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010Abanti Sahoo Abstract An available theoretical model for mixing index in gas-solid fluidized bed has been analyzed for further modification and improvement. Assumption of 50% bed material moving in the upward direction and rest 50% in the downward direction considered for the above model (the counter-flow circulation model) has been analyzed for optimum result. A computer program was run for different bed conditions by varying operating parameters, namely, the mixture composition, fractions of bed materials, minimum fluidization velocity of the jetsam particles and that of the bed materials (i.e. mixture of the jetsam and the flotsam particles). The developed model was solved by finite difference (central differencing). Fraction of the bed material moving in the upward direction was varied from 0 to 100% and the minimum fluidization velocity was varied within the Umf of the flotsam to that of the jetsam particles (i.e. 0.465,1.0335 m/s). Optimum fraction of bed materials with respect to its distribution (as per the earlier proposed model) in the upward and downward streams during the fluidization process was found to be 20 and 80%, respectively. The modified model was validated by conducting experiments on fluidization and studying the mixing characteristics of regular homogeneous materials (sago) in a 15 × 100 cm cylindrical column. Fairly good agreement was observed between the values of mixing index obtained from the proposed modified model and the experimental observations. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Medial septal modulation of the ascending brainstem hippocampal synchronizing pathways in the freely moving ratHIPPOCAMPUS, Issue 1 2006Brian H. Bland Abstract Rats implanted with hippocampal recording electrodes were tested in a wheel-running apparatus under three conditions: (1) independent electrical stimulation of the medial septal nucleus (MS); (2) independent electrical stimulation of the posterior hypothalamic nucleus (PH); and (3) combined electrical stimulation of the MS and PH using pairings of two stimulation conditions, 7 or10 Hz stimulation of the MS, and a low- or high-intensity PH stimulation. Quantitative measures of running speed were taken, and hippocampal recordings were subjected to fast-Fourier transform analysis. Electrical stimulation of the PH induced wheel-running behavior; running speed and the accompanying hippocampus (HPC) theta frequency increased with increase in stimulation intensity. Electrical stimulation of the MS failed to induce wheel-running behavior despite the fact that HPC theta was induced at the frequency of the applied stimulation (7 and 10 Hz). Electrical stimulation of the MS reset the frequency of HPC theta induced by PH stimulation in both the upward and downward directions and increased theta power, while wheel-running speed was modulated in a downward direction only. © 2005 Wiley-Liss, Inc. [source] Divergent selection and realized heritability for growth in the Japanese scallop, Patinopecten yessoensis JayAQUACULTURE RESEARCH, Issue 9 2010Jun Liang Abstract In order to improve the production and accurately estimate response to selection, divergent selection for growth in shell height was conducted in a cultured population of the Japanese scallop Patinopecten yessoensis. Applying the same selection intensity ± 1.756 in upward and downward directions, three groups including two selected groups of Fast and Slow and one non-selected Control group were created, which were reared under the same environmental conditions at any stage. Differences always significantly existed among the three groups (P<0.05), except for larvae at day 1 and at day 5, and in the order of Fast>Control>Slow. The average standardized response to selection (SR), realized heritability (hR2) and genetic gain (GG) was 0.473%, 0.269% and 7.85% for the Fast group and 0.381%, 0.217% and 6.60% for the Slow group respectively. Moreover, significant differences (P<0.05) were detected between the fast and the slow lines in both SR and hR2, providing evidence for an asymmetric response in two directions. Performance in shell height is improved by 7.85% in the fast line after one generation selection, suggesting that mass selection for faster growth in a cultured population of the Japanese scallop is effective. [source] | ||||||||||