Other Phases (other + phase)

Distribution by Scientific Domains

Selected Abstracts

A Note on the Interdependence between Hypothesis Generation and Information Search in Conducting Analytical Procedures,

Stephen K. Asare
Abstract This study examines the linkage among the initial hypothesis set, the information search, and decision performance in performing analytical procedures. We manipulated the quality of the initial hypothesis set and the quality of the information search to investigate the extent to which deficiencies (or benefits) in either process can be remedied (or negated) by the other phase. The hypothesis set manipulation entailed inheriting a correct hypothesis set, inheriting an incorrect hypothesis set, or generating a hypothesis set. The information search was manipulated by providing a balanced evidence set to auditors (i.e., evidence on a range of likely causes including the actual cause - analogous to a standard audit program) or asking them to conduct their own search. One hundred and two auditors participated in the study. The results show that auditors who inherit a correct hypothesis set and receive balanced evidence performed better than those who inherit a correct hypothesis set and did their own search, as well as those who inherited an incorrect hypothesis set and were provided a balanced evidence set. The former performance difference arose because auditors who conducted their own search were found to do repeated testing of non-errors and truncated their search. This suggests that having a correct hypothesis set does not ensure that a balanced testing strategy is employed, which, in turn, diminishes part of the presumed benefits of a correct hypothesis set. The latter performance difference was attributable to auditors' failure to generate new hypotheses when they received evidence about a hypothesis that was not in the current hypothesis set. This demonstrates that balanced evidence does not fully compensate for having an initial incorrect hypothesis set. These findings suggest the need for firm training and/or decision aids to facilitate both a balanced information search and an iterative hypothesis generation process. [source]

Role of GABAA inhibition in modulation of pyramidal tract neuron activity during postural corrections

Zinaida A. Tamarova
Abstract In a previous study we demonstrated that the activity of pyramidal tract neurons (PTNs) of the motor cortex is modulated in relation to postural corrections evoked by periodical tilts of the animal. The modulation included an increase in activity in one phase of the tilt cycle and a decrease in the other phase. It is known that the motor cortex contains a large population of inhibitory GABAergic neurons. How do these neurons participate in periodic modulation of PTNs? The goal of this study was to investigate the role of GABAA inhibitory neurons of the motor cortex in the modulation of postural-related PTN activity. Using extracellular electrodes with attached micropipettes, we recorded the activity of PTNs in cats maintaining balance on a tilting platform both before and after iontophoretic application of the GABAA receptor antagonists gabazine or bicuculline. The tilt-related activity of 93% of PTNs was affected by GABAA receptor antagonists. In 88% of cells, peak activity increased by 75 50% (mean SD). In contrast, the trough activity changed by a much smaller value and almost as many neurons showed a decrease as showed an increase. In 73% of the neurons, the phase position of the peak activity did not change or changed by no more than 0.1 of a cycle. We conclude that the GABAergic system of the motor cortex reduces the posture-related responses of PTNs but has little role in determining their response timing. [source]

Social Networks and Entrepreneurship

Arent Greve
We study network activities of entrepreneurs through three phases of establishing a firm in four countries. Entrepreneurs access people in their networks to discuss aspects of establishing and running a business. We find that entrepreneurs build networks that systematically vary by the phase of entrepreneurship, analyzing number of their discussion partners, and the time spent networking. Entrepreneurs talk with more people during the planning than other phases. Family members are present in their networks in all phases, particularly among those who took over an existing firm. However, women use their kin to a larger extent than men, and even more than men when they take over an existing firm. Experienced entrepreneurs have the same networking patterns as novices. Moreover, these networking patterns are the same in all countries. However, there are country differences in size of discussion networks and time spent networking. [source]

Overwinter mass loss of snowshoe hares in the Yukon: starvation, stress, adaptation or artefact?

Summary 1Overwinter mass loss can reduce energetic requirements in mammals (Dehnel's phenomenon). Alternatively, mass loss can result from food limitation or high predation risk. 2We use data from fertilizer, food-supplementation and predator-exclusion experiments in the Yukon during a population cycle from 1986 to 1996 to test the causes of overwinter mass loss by snowshoe hares (Lepus americanus). In all years, some hares on control sites gained mass overwinter. During the increase phase the majority gained mass, but in all other phases the majority lost mass. 3Snowshoe hares weighing < 1000 g in autumn always gained mass overwinter, as did the majority that weighed 1000,1400 g. Hares weighing > 1800 g in autumn usually lost mass. 4Snowshoe hares on the predator-exclosure + food site gained mass overwinter in all years. Hares on the food-supplementation sites lost mass during the decline but gained mass in all other phases. Fertilization had little effect on mass dynamics. 5Snowshoe hares were more likely to lose mass during winters with low survival rates. Snowshoe hares on the predator-exclosure treatments were more likely to gain mass than were hares on control sites. 6Overwinter mass loss was correlated with maximum snow depth. At equivalent snow depths, hares on food-supplemented areas lost 98 g ( 146 SE) less on average than hares on the controls and predator-exclosure treatment. 7Bone-marrow fat was related to body mass and cause of death. Small hares had the lowest marrow fat. Hares killed by humans had higher marrow fat than those killed by predators; hares that simply died had the lowest marrow fat. Hares on food-supplemented sites had the highest kidney and marrow fat. 8Overwinter-mass loss for snowshoe hares is explained interactively by winter conditions, food supply, predation risk and autumn mass. Some snowshoe hares lost mass overwinter in all years and on all treatments, suggesting that reducing body mass may facilitate survival, especially in cases where foraging costs are high energetically or increase predation risk. [source]

Phase relations in the Ba,Sr,Co,Fe,O system at 1273,K in air

Zhn Yng
Selected compositions of the Ba,Sr,Co,Fe,O system were synthesized from powders by the solid-state reaction method. Samples were equilibrated at 1273,K for 36,000,s in air. The resulting powders were characterized by X-ray diffraction (XRD) at room temperature and by high-temperature in situ XRD. The phases present in the BaxSr1,xCoyFe1,yO3,, system are outlined for 1273,K in air. For most of the quaternary compositions, the cubic perovskite is formed, except for the compositions with x = 1 (excluding y = 0.4), y = 1 and x, y = 0.8, where the phases mainly show hexagonal distortions, and x, y = 0, for which a predominant cubic phase is mixed with other phases. [source]

Cooperative use of unmanned sea surface and micro aerial vehicles at Hurricane Wilma

Robin R. Murphy
On Oct. 24, 2005, Hurricane Wilma, a category 5 storm, made landfall at Cape Romano, Florida. Three days later, the Center for Robot-Assisted Search and Rescue at the University of South Florida deployed an iSENYS helicopter and a prototype unmanned water surface vehicle, AEOS-1, to survey damage in parts of Marco Island, 14 km from landfall. The effort was the first known use of unmanned sea surface vehicles (USVs) for emergency response and established their suitability for the recovery phase of disaster management by detecting damage to seawalls and piers, locating submerged debris (moorings and handrails), and determining safe lanes for sea navigation. It provides a preliminary domain theory of postdisaster port and littoral inspection with unmanned vehicles for use by the human,robot interaction community. It was also the first known demonstration of the strongly heterogeneous USV,micro aerial vehicle (MAV) team for any domain. The effort identified cooperative UAV,USV strategies and open issues for autonomous operations near structures. The effort showed that the MAV provided a much-needed external view for situation awareness and provided spotting for areas to be inspected. Concepts of operations for USV damage inspection and USV,MAV cooperation emerged, including a formula for computing the human,robot ratio: Nh = (2 Nv) + 1, where Nh is the number of humans and Nv is the number of vehicles. The outstanding research issues span three areas: challenges for USVs operating near littoral structures, general issues for USV,MAV cooperation, and new applications. It is expected that the lessons learned will be transferrable to defense and homeland safety and security applications, such as port security, and other phases of emergency response, including rescue. 2008 Wiley Periodicals, Inc. [source]

Occlusal phase of gum-chewing strokes

H. Hayasaki
summary, The occlusal phase of chewing is especially interesting because food particles are being pulverized in this phase. For efficient chewing the upper and lower teeth must come together in a congruent fashion with less variation than in other phases. To examine this expectation the chewing motions of 28 women were recorded optoelectrically, and their frontal and sagittal angles of the closing and following opening strokes were measured at 30 mm (3-D linear distance) of opening. Closing strokes were more stable than opening strokes. The frontal angle was correlated with the sagittal angle during closing. The opening and closing sagittal angles were moderately correlated, and the opening and closing frontal angles were negatively correlated at the intersubject level. No direct association was found between the closing strokes and following opening strokes at the intra-subject level. These results suggest that closing strokes are more stable than opening strokes, resulting in efficient mastication. [source]

Effects of Prenatal Ethanol Exposure on Hypothalamic-Pituitary-Adrenal Function Across the Estrous Cycle

ALCOHOLISM, Issue 6 2009
Ni Lan
Background:, Rats prenatally exposed to ethanol (E) typically show increased hypothalamic-pituitary-adrenal (HPA) responses to stressors in adulthood. Importantly, prenatal ethanol may differentially alter stress responsiveness in male and female offspring, suggesting a role for the gonadal hormones in mediating the effects of ethanol on HPA activity. We investigated the role of ethanol-induced changes in hypothalamic-pituitary-gonadal (HPG) activity in the differential HPA regulation observed in E compared to control females across the estrous cycle. Methods:, Peripheral hormones and changes in central neuropeptide mRNA levels were measured across the estrous cycle in adult female offspring from E, pair-fed (PF) and ad libitum-fed control (C) dams. Results:, Ethanol females showed normal estrous cyclicity (vaginal smears) but delayed sexual maturation (vaginal opening). Both HPG and HPA activity were differentially altered in E (and in some cases, PF) compared to control females as a function of estrous cycle stage. In relation to HPG activity, E and PF females had higher basal and stress estradiol (E2) levels in proestrus compared to other phases of the cycle, and decreased GnRH mRNA levels compared to C females in diestrus. Further, E females had greater variation in LH than PF and C females across the cycle, and in proestrus, only E females showed a significant LH increase following stress. In relation to HPA activity, both basal and stress CORT levels and overall ACTH levels were greater in E than in C females in proestrus. Furthermore, AVP mRNA levels were increased overall in E compared to PF and C females. Conclusions:, These data demonstrate ethanol-induced changes in both HPG and HPA activity that are estrous phase-specific, and support the possibility that changes in HPA activity in E females may reflect differential sensitivity to ovarian steroids. E females appear to have an increased HPA sensitivity to E2, and a possible shift toward AVP regulation of HPA activity. That PF were similar to E females on some measures suggests that nutritional effects of diet or food restriction played a role in mediating at least some of the changes observed. [source]

Raman spectroscopy of Bi-Te thin films

V. Russo
Abstract The deposition of micro- and nanocrystalline bismuth telluride thin films with tailored structure and composition is of interest in view of improving the well-known material thermoelectric properties. Only a few works exist that discuss Raman scattering of Bi2Te3 crystals and films, while a Raman characterization of other phases, i.e. other lesser known compounds of the Bi-Te system, such as tsumoite (BiTe) and pilsenite (Bi4Te3), is still completely lacking. We here present a Raman investigation of Bi-Te polycrystalline thin films with controlled structure (stoichiometry and growth orientation), morphology and phase composition, produced by nanosecond pulsed laser deposition. Interpretation of Raman spectra from Bi-Te films was supported by scanning electron microscopy, energy dispersive spectroscopy (EDS) and X-Ray diffraction measurements, together with the predictions of the group theory. In this way, the first Raman characterization of Bi-rich phases (namely BiTe and Bi4Te3) has been obtained. For Bi-Te compositions characterized by a high Bi or Te content, Raman spectra reveal that segregation of elemental Bi or Te occurs. Copyright 2008 John Wiley & Sons, Ltd. [source]

Thermophysical Properties of Complex Rare-Earth Zirconate Ceramic for Thermal Barrier Coatings

Liu Ling
Two complex rare-earth zirconates (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4 and (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 for thermal barrier coatings (TBCs) were synthesized by the coprecipitation method. Their phase composition, microstructure, and thermophysical properties were investigated. X-ray diffractometry results revealed that single-phase (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4 and (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 with pyrochlore structure were prepared, and the scanning electron microscopy results showed that the microstructures of the products were dense and no other phases existed among the grains. With the temperature increasing, the thermal expansion coefficient (CTE) of the ceramics increased, while the thermal conductivity decreased. The results indicated that the CTE of (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 was slightly higher than that of (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4 and the thermal conductivity of (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 was lower than that of (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4. These results imply that the thermophysical properties of (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 are better than that of (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4 as the material for the ceramic layer in the TBC system. [source]

Preparation of Highly Dispersed Ultrafine Barium Titanate Powder by Using Microbial-Derived Surfactant

Hidehiro Kamiya
To uniformly disperse ultrafine BaTiO3 particles with a stoichiometric composition and several tens of nanometers in diameter to primary particles during the sol,gel synthesis process, a new aqueous surfactant with a high hydrophilic group density and special cis-structure was prepared from a microbial product and added to solution before the sol,gel synthesis reaction. Because of the rapid formation of large and porous aggregates which were 30,50 ,m in diameter in suspension without addition of this unique structural surfactant, the prepared ultrafine BaTiO3 particles caused rapid sedimentation in suspension. The addition of the surfactant in the range of 7.1 wt% for the synthesized BaTiO3 particles made it possible to decrease the size of the aggregates in suspension as well as the sedimentation velocity while maintaining the stoichiometric composition. The optimum additive content to obtain the minimum aggregate size of about 100,200 nm in diameter and the highest dispersion stability in suspension while maintaining the stoichiometric composition of prepared ultrafine BaTiO3 particles without other phases was determined at about 7.1 wt%. Because the excess addition of this surfactant at more than 8.5 wt% inhibited the uniform synthesis of BaTiO3 particles, an amorphous phase with a highly specific surface area and a BaCO3 phase formed in the synthesized particles. [source]

Petrology of Martian meteorite Northwest Africa 998

This 456-gram, partially fusion-crusted meteorite consists of (by volume) ,75% augite (core composition Wo39En39Fs22), ,9% olivine (Fo35), ,7% plagioclase (Ab61An35) as anhedra among augite and olivine, ,3.5% low-calcium pyroxenes (pigeonite and orthopyroxene) replacing or forming overgrowths on olivine and augite, ,1% titanomagnetite, and other phases including potassium feldspar, apatite, pyrrhotite, chalcopyrite, ilmenite, and fine-grained mesostasis material. Minor secondary alteration materials include "iddingsite" associated with olivine (probably Martian), calcite crack fillings, and iron oxide/hydroxide staining (both probably terrestrial). Shock effects are limited to minor cataclasis and twinning in augite. In comparison to other nakhlites, NWA 998 contains more low-calcium pyroxenes and its plagioclase crystals are blockier. The large size of the intercumulus feldspars and the chemical homogeneity of the olivine imply relatively slow cooling and chemical equilibration in the late- and post-igneous history of this specimen, and mineral thermometers give subsolidus temperatures near 730 C. Oxidation state was near that of the QFM buffer, from about QFM-2 in earliest crystallization to near QFM in late crystallization, and to about QFM + 1.5 in some magmatic inclusions. The replacement or overgrowth of olivine by pigeonite and orthopyroxene (with or without titanomagnetite), and the marginal replacement of augite by pigeonite, are interpreted to result from late-stage reactions with residual melts (consistent with experimental phase equilibrium relationships). Apatite is concentrated in planar zones separating apatite-free domains, which suggests that residual magma (rich in P and REE) was concentrated in planar (fracture?) zones and possibly migrated through them. Loss of late magma through these zones is consistent with the low bulk REE content of NWA 998 compared with the calculated REE content of its parent magma. [source]

The possible factors affecting suicide attempts in the different phases of the menstrual cycle

Abstract, This study was designed to investigate whether there is a relationship between the menstrual cycle and suicide attempts, and to determine the factors affecting suicide attempts in different phases of the menstrual cycle. The study sample included 52 women who were admitted to the emergency room because of a suicide attempt. The incidence of suicide attempts in menstrual follicular phase (MFP) was significantly higher than in other phases. No significant difference of socio-demographic and clinical characteristics was observed between MFP and the other phases. Also, hormone levels of patients who attempted suicide were not different from those of healthy control subjects. In spite of the fact that suicide attempts were often made in MFP, there was substantial difficulty in explaining why this frequency was different than other phases. Furthermore, the event may be linked to low estrogen and progesterone levels in this phase. It has, however, been thought that hormonal effects cannot be responsible alone for suicide attempts. [source]

Polymorphism of CaTeO3 and solid solutions CaxSr1,,,xTeO3

Berthold Stger
Single crystals and microcrystalline samples of the calcium tellurate(IV) phases ,-, ,-, ,,- and ,-CaTeO3 as well as of two solid solutions CaxSr1,,,xTeO3 (x = 0.55 and 0.77) have been synthesized and characterized by X-ray diffraction and thermal analysis. A comparative description of the structures and the relations between the polymorphs is given. The main building units of the hitherto unknown structures are isolated [TeIVO3]2, units and [(Ca,Sr)Ox] (x = 6,8) polyhedra. All structures exhibit channels in which the TeIV electron lone pairs protrude. The low-temperature phase ,-CaTeO3 is stable up to 1168,K. It exhibits nearly cylindrical channels (diameter ,,4,) and differs structurally from the other phases, whereas the metastable high-temperature phases are closely related to each other. They feature oval channels (shortest and longest diameter ,,2 and 8,). ,-CaTeO3 can be described as an order,disorder (OD) structure of two non-polar layers with layer groups p121/m1 and p1211. The ,-CaTeO3 crystal under investigation consists of two polytypes with a maximum degree of order. The two phases CaxSr1,,,xTeO3 (x = 0.55 and 0.77) are isostructural to the MDO1 polytype of ,-CaTeO3. ,-CaTeO3 shows a distinct reversible phase transition at ,,293,K. The low-temperature modification ,,-CaTeO3 as well as its high-temperature modification ,-CaTeO3 can be considered as threefold superstructures along [100] based on the MDO1 polytype of ,-CaTeO3. [source]

Structural basis for the phase transitions of Cs2HgCl4

Bagautdin Bagautdinov
The a0 b0 2c0 twofold superstructure of dicaesium mercury tetrachloride, Cs2HgCl4, at T = 120,K has been determined by single-crystal X-ray diffraction using synchrotron radiation. Lattice parameters were found as a = 9.7105,(2), b = 7.4691 (1), c = 26.8992 (4) , and , = 90.368,(1) with the supercell space group P21/c. Refinements on 1828 observed unique reflections converged to R = 0.053 (wR = 0.057) using anisotropic temperature factors for all atoms. This phase is the stable phase of Cs2HgCl4 below 163,K. A quantitative comparison is made of the distortions of the 2c0 superstructure with the undistorted phase that is stable at room temperature, and with the 3c0 and 5a0 superstructures that are stable at temperatures between 163,K and room temperature. The principal difference between the 2c0 superstructure and all other phases of Cs2HgCl4 is that the Cs cations are displaced away from the centers of their coordination polyhedra in the 2c0 superstructure. The structural basis for the driving force of the series of phase transitions in this compound is found in the variations of the environments of Cs atoms and in the variations of the distortions of the HgCl4 tetrahedra. [source]

Speciation of heavy metals in sediments from Baihua Lake and Aha Lake

Xian-fei Huang
Abstract Baihua Lake and Aha Lake are both drinking-water sources for Guiyang City, the capital of Guizhou Province in southwestern China. In the present research, chemical speciation of chromium (Cr), copper (Cu) and zinc (Zn) in the sediments from these two lakes was studied based on the sequential extraction procedure developed by Tessier et al., and organic matter (OM) was determined by ignition method. The results obtained are as follows:1 The organic matter amounts in sediments from Baihua Lake and Aha Lake ranged from 11.62 to 18.02% and 8.48 to 13.90%, respectively;2 Cr and Zn were mainly distributed in residual phase, while Cu mainly existed in oxidizable and residual phases;3 Levels of Cu distributed in oxidizable phase in sediments from Baihua Lake were higher than those from Aha Lake;4 Mobility, bioavailability, and toxicity of Cu were low in comparison with Zn and Cr, because Cu was mainly distributed in oxidizable and residual phases in which heavy metals mobility was lower than in the other phases. The Pearson's correlation coefficient between organic matter and Cr in oxidizable phase of the 20 sediment samples collected from the two lakes was up to 0.604 (p < 0.01). Copyright 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Cell death induction by isothiocyanates and their underlying molecular mechanisms

BIOFACTORS, Issue 2 2006
Yoshimasa Nakamura
Abstract An important and promising group of compounds that have a chemopreventive property are organosulfur compounds, such as isothiocyanates (ITCs). In recent years, it has been shown that ITCs induce apoptosis in various cancer cell lines and experimental rodents. During the course of apoptosis induction by ITC, multiple signal-transduction pathways and apoptosis intermediates are modulated. We have also clarified the molecular mechanism underlying the relationship between cell cycle arrest and apoptosis induced by benzyl isothiocyanate (BITC), a major ITC compound isolated from papaya. The exposure of cells to BITC resulted in the inhibition of the G2/M progression that coincided with not only the up-regulated expression of the G2/M cell cycle arrest-regulating genes but also the apoptosis induction. The experiment using the phase-specific synchronized cells demonstrated that the G2/M phase-arrested cells are more sensitive to undergoing apoptotic stimulation by BITC than the cells in other phases. We identified the phosphorylated Bcl-2 as a key molecule linking the p38 MAPK-dependent cell cycle arrest with the JNK activation by BITC. We also found that BITC induced the cytotoxic effect more preferentially in the proliferating normal human colon epithelial cells than in the quiescent cells. Conversely, treatment with an excessive concentration of BITC resulted in necrotic cell death without DNA ladder formation. This review addresses the biological impact of cell death induction by BITC as well as other ITCs and the involved signal transduction pathways. [source]