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1

Homogenization of periodic systems with large potentials  

Microsoft Academic Search

We consider the homogenization of a system of second-order equa- tions with a large potential in a periodic medium. Denoting by † the period, the potential is scaled as †¡2. Under a generic assumption on the spectral properties of the associated cell problem, we prove that the solution can be approximately factorized as the product of a fast oscillating cell

Grégoire Allaire; Yves Capdeboscq; Andrey Piatnitski; Vincent Siess; M. Vanninathan

2004-01-01

2

Calculations in support of a potential definition of large release  

SciTech Connect

The Nuclear Regulatory Commission has stated a hierarchy of safety goals with the qualitative safety goals as Level I of the hierarchy, backed up by the quantitative health objectives as Level II and the large release guideline as Level III. The large release guideline has been stated in qualitative terms as a magnitude of release of the core inventory whose frequency should not exceed 10{sup -6} per reactor year. However, the Commission did not provide a quantitative specification of a large release. This report describes various specifications of a large release and focuses, in particular, on an examination of releases which have a potential to lead to one prompt fatality in the mean. The basic information required to set up the calculations was derived from the simplified source terms which were obtained from approximations of the NUREG-1150 source terms. Since the calculation of consequences is affected by a large number of assumptions, a generic site with a (conservatively determined) population density and meteorology was specified. At this site, various emergency responses (including no response) were assumed based on information derived from earlier studies. For each of the emergency response assumptions, a set of calculations were performed with the simplified source terms; these included adjustments to the source terms, such as the timing of the release, the core inventory, and the release fractions of different radionuclides, to arrive at a result of one mean prompt fatality in each case. Each of the source terms, so defined, has the potential to be a candidate for a large release. The calculations show that there are many possible candidate source terms for a large release depending on the characteristics which are felt to be important.

Hanson, A.L.; Davis, R.E.; Mubayi, V.

1994-05-01

3

How Large Are Cognitive Gender Differences?  

ERIC Educational Resources Information Center

|This study applied meta-analysis techniques to the gender studies cited by Maccoby and Jacklin and assessed the magnitude of cognitive gender differences. Results indicated that gender differences in verbal, quantitative, and visual-spatial ability were very small. (Author/APM)|

Hyde, Janet Shibley

1981-01-01

4

Zooplankton as Potential Indicators of Biotic Condition in Large Rivers  

Microsoft Academic Search

As part of the Environmental Monitoring and Assessment Program (EMAP), supported by the U.S. Environmental Protection Agency, we are examining zooplankton diversity and abundance in three large rivers (Missouri, Ohio, and upper Mississippi). These rivers are particularly interesting because of large differences in their hydrologic patterns, resulting primarily from their different management strategies. Preliminary data from summer 2004 surveys of

K. A. Medley; J. E. Havel; J. D. Jack

2005-01-01

5

Lichtheimia Species Exhibit Differences in Virulence Potential  

PubMed Central

Although the number of mucormycosis cases has increased during the last decades, little is known about the pathogenic potential of most mucoralean fungi. Lichtheimia species represent the second and third most common cause of mucormycosis in Europe and worldwide, respectively. To date only three of the five species of the genus have been found to be involved in mucormycosis, namely L. corymbifera, L. ramosa and L. ornata. However, it is not clear whether the clinical situation reflects differences in virulence between the species of Lichtheimia or whether other factors are responsible. In this study the virulence of 46 strains of all five species of Lichtheimia was investigated in chicken embryos. Additionally, strains of the closest-related genus Dichotomocladium were tested. Full virulence was restricted to the clinically relevant species while all strains of L. hyalospora, L. sphaerocystis and Dichotomocladium species were attenuated. Although virulence differences were present in the clinically relevant species, no connection between origin (environmental vs clinical) or phylogenetic position within the species was observed. Physiological studies revealed no clear connection of stress resistance and carbon source utilization with the virulence of the strains. Slower growth at 37°C might explain low virulence of L. hyalospora, L. spaherocystis and Dichotomocladium; however, similarly slow growing strains of L. ornata were fully virulent. Thus, additional factors or a complex interplay of factors determines the virulence of strains. Our data suggest that the clinical situation in fact reflects different virulence potentials in the Lichtheimiaceae.

Schwartze, Volker U.; Hoffmann, Kerstin; Nyilasi, Ildiko; Papp, Tamas; Vagvolgyi, Csaba; de Hoog, Sybren; Voigt, Kerstin; Jacobsen, Ilse D.

2012-01-01

6

Accuracy potential of large-format still-video cameras  

NASA Astrophysics Data System (ADS)

High resolution digital stillvideo cameras have found wide interest in digital close range photogrammetry in the last five years. They can be considered fully autonomous digital image acquisition systems without the requirement of permanent connection to an external power supply and a host computer for camera control and data storage, thus allowing for convenient data acquisition in many applications of digital photogrammetry. The accuracy potential of stillvideo cameras has been extensively discussed. While large format CCD sensors themselves can be considered very accurate measurement devices, lenses, camera bodies and sensor mounts of stillvideo cameras are not compression techniques in image storage, which may also affect the accuracy potential. This presentation shows recent experiences from accuracy tests with a number of large format stillvideo cameras, including a modified Kodak DCS200, a Kodak DCS460, a Nikon E2 and a Polaroid PDC-2000. The tests of the cameras include absolute and relative measurements and were performed using strong photogrammetric networks and good external reference. The results of the tests indicate that very high accuracies can be achieved with large blocks of stillvideo imagery especially in deformation measurements. In absolute measurements, however, the accuracy potential of the large format CCD sensors is partly ruined by a lack of stability of the cameras.

Maas, Hans-Gerd; Niederoest, Markus

1997-07-01

7

Coupling between Cortical Potentials from Different Areas  

Microsoft Academic Search

At any instant, the electroencephalogram can be classified as to (i) polarity and (ii) direction of change in polarity. This classification provides a way to measure coupling between cortical areas. The technique is simple, yet of wide potential utility for studying functional relationships between cortical areas. The results of applying this technique suggest how the potentials giving rise to the

Enoch Callaway; Peter R. Harris

1974-01-01

8

Lichtheimia Species Exhibit Differences in Virulence Potential  

Microsoft Academic Search

Although the number of mucormycosis cases has increased during the last decades, little is known about the pathogenic potential of most mucoralean fungi. Lichtheimia species represent the second and third most common cause of mucormycosis in Europe and worldwide, respectively. To date only three of the five species of the genus have been found to be involved in mucormycosis, namely

Volker U. Schwartze; Kerstin Hoffmann; Ildikó Nyilasi; Tamás Papp; Csaba Vágvölgyi; Sybren de Hoog; Kerstin Voigt; Ilse D. Jacobsen

2012-01-01

9

Assessment of large-scale flood events by different indicators  

NASA Astrophysics Data System (ADS)

An analysis of real large-scale flood events reveals that there is considerable variation in the return periods of the discharges within a river basin. The assessment of the return period of the whole event has thus to be evaluated on the basis of the overall impact of the event. For example, a frequency analysis of a series of annual flood damages (loss accumulation) would enable us to assign an exceedance probability to each event. However, in practise, time series of losses or other impact variables are hardly available or their usage is limited due to changes in time of the land use of the areas prone to inundation and their assets (building values, assets of companies and infrastructure). Using a reach at the River Rhine between the gauges Maxau and Rees as an example, a probabilistic model for the calculation of flood risks has been set up. The model is based on a flood classification at the river Rhine, which is then combined with flood frequency, correlation and regression analyses. Inundation areas are calculated by means of a hydraulic transformation. In the framework of a Monte-Carlo-Simulation 100 flood scenarios were derived and different impact parameters were determined, i.e. the total inundated area, the inundated settlement and industrial area, the exposed population as well as the potential damage to residential buildings as estimated by the loss model FLEMOps. The impact analyses were further used to construct a frequency distribution of each impact variable. By these the return periods of a number of historical flood events and a few static flood scenarios that were used for hazard mapping were estimated. The results will be discussed in the context of risk transfer systems and risk communication issues.

Thieken, A. H.; Merz, B.; Apel, H.

2009-04-01

10

Central ridge of Newfoundland: Little explored, potential large  

SciTech Connect

The Central ridge on the northeastern Grand Banks off Newfoundland represents a large area with known hydrocarbon accumulations and the potential for giant fields. It covers some 17,000 sq km with water less than 400 m deep. The first major hydrocarbon discovery on the Newfoundland Grand Banks is giant Hibernia field in the Jeanne d'Arc basin. Hibernia field, discovered in 1979, has reserves of 666 million bbl and is due onstream in 1997. Since Hibernia, 14 other discoveries have been made on the Grand Banks, with three on the Central ridge. Oil was first discovered on Central Ridge in 1980 with the Mobil et al. South Tempest G-88 well. In 1982 gas was discovered with the Mobil et al. North Dana I-43 well 30 km northeast of the earlier discovery. In 1983 gas and condensate were discovered with the Husky-Bow Valley et al. Trave E-87 well 20 km south of the South Tempest well. These discoveries are held under significant discovery licenses and an additional 2,400 sq km are held under exploration licenses. The paper discusses the history of the basin, the reservoir source traps, and the basin potential.

Silva, N.R. De (Canada-Newfoundland Offshore Petroleum Board, Newfoundland, St. Johns (Canada))

1993-10-25

11

Individual skill differences and large-scale environmental learning.  

PubMed

Spatial skills are known to vary widely among normal individuals. This project was designed to address whether these individual differences are differentially related to large-scale environmental learning from route (ground-level) and survey (aerial) perspectives. Participants learned two virtual environments (route and survey) with limited exposure and tested on judgments about relative locations of objects. They also performed a series of spatial and nonspatial component skill tests. With limited learning, performance after route encoding was worse than performance after survey encoding. Furthermore, performance after route and survey encoding appeared to be preferentially linked to perspective and object-based transformations, respectively. Together, the results provide clues to how different skills might be engaged by different individuals for the same goal of learning a large-scale environment. PMID:16719662

Fields, Alexa W; Shelton, Amy L

2006-05-01

12

Finite difference analysis of electrically large parabolic reflector antennas  

Microsoft Academic Search

A reflector antenna is analyzed using the finite-difference method (FD). The induced current densities on an axially symmetric parabolic reflector are rigorously calculated. The measured equation of invariance (MEI) is used to terminate the FD mesh very close to the reflector surface. To take advantage of the axial symmetry, the theory of coupled-azimuthal potentials (CAPs) is employed. Illustrative results are

Yong-Lun Luo; Kwai-Man Luk; Kenneth K. Mei; Edward Kai-Ning Yung

2002-01-01

13

Near-field of coaxial jets with large density differences  

Microsoft Academic Search

The paper describes an experimental investigation of coaxial jets with large density differences. Measurements by various\\u000a techniques show that density effects on the flow dynamics are taken into account to first order by considering the specific\\u000a outer to inner jet momentum flux ratio M and not separately the density and velocity ratios. A regime of recirculation occurs for M higher

M. Favre-Marinet; E. B. Camano; J. Sarboch

1999-01-01

14

Potential Formation and Thermal Insulation between Different Temperature Plasmas  

Microsoft Academic Search

Potential formation and reduction of electron heat flow between different temperature plasmas are studied by particle simulations. It is found that the amplitude and even the polarity of the potential difference is controlled by the ion to electron thermal velocity ratio. When the ion thermal speed is smaller than the electron thermal speed, the positive potential jump from the cold

Seiji Ishiguro

1987-01-01

15

Assessing carbon dynamics in semiarid ecosystems : Balancing potential gains with potential large rapid losses  

SciTech Connect

Photosynthesis and respiration are the largest fluxes into and out of the biosphere (Molles 1999). Consequently, small changes in these fluxes can potentially produce large changes in the storage of carbon in the biosphere. Terrestrial carbon fluxes account for more than half of the carbon transferred between the atmosphere and the earth's surface (about 120 GigaTons/year), and current stores of carbon in terrestrial ecosystem are estimated at 2060 GigaTons. Increasing attention is being focused on the role of managing and sequestering carbon in the terrestrial biosphere as a means for addressing global climate change (IGBP, 1998; U.S. Department of Energy, 1999). Terrestrial ecosystems are widely recognized as a major biological scrubber for atmosphereic CO{sub 2} and their ability to finction as such can be increased significantly over the next 25 years through careful manipulation. The potential for terrestrial carbon gains has been the subject of much attention (Dixon et al., 1994; Masera et al. 1997; Cao and Woodward, 1998; DeLucia et al. 1999). In contrast to other strategies for reducing net carbon emissions, terrestrial sequestration has the potential for rapid implementation. Strategies that focus on soil carbon are likely to be effective because in addition to being a storage pool of carbon, soil carbon also improves site productivity through improving soil quality (e.g., water retention and nutrient availability). The carbon pool in soils is immense and highly dynamic. The flux of carbon into and out of soils is one of the largest uncertainties in the total mass balance of global carbon (NRC, 1999; La1 et al., 1998; Cambardella, 1998). Reducing these uncertainties is key to developing carbon sequestration strategies. Soil carbon pools have been greatly depleted over recent centuries, and there is potential to increase storage of carbon in these soils through effective land management. Whereas carbon in vegetation can be managed directly through land use, carbon in soils generally must be managed indirectly through manipulation of vegetation and nutrients. Land management as well as climate changes have the potential to increase soil carbon, but also could trigger large soil carbon losses. Recently, the importance of accounting for countervailing losses in assessing potential amounts of terrestrial carbon that can be sequestered has been highlighted (Schlesinger, 1999; Walker et al., 1999). Realistic assessment of terrestrial carbon sequestration strategies must consider net results of an applied strategy, not simply projected carbon gains. In addition, large, rapid losses of carbon resulting from carbon management strategies could exacerbate the global warming rather than mitigating it. Such potential losses include rapid loss of carbon in vegetation due to fire and rapid loss of soil carbon triggered by reductions in ground cover (e.g., fire, drought). Therefore, strategies for terrestrial carbon sequestration must determine how to increase terrestrial carbon while minimizing the risk of large-scale catastrophic losses. Our objectives in this paper are to (1) highlight approaches that are being considered in terms of terrestrial carbon sequestration, (2) highlight case studies for which large losses of carbon may occur, and (3) suggest future directions and application for terrestrial carbon sequestration.

Breshears, D. D. (David D.); Ebinger, M. H. (Michael H.); Unkefer, P. J. (Pat J.)

2001-01-01

16

The density field of coaxial jets with large velocity ratio and large density differences  

Microsoft Academic Search

This paper describes an experimental investigation of the density field of coaxial jets with large density differences. These flows are characterised by a low velocity–high density inner jet surrounded by a high velocity–low density annular jet. The density field was determined by a thermo-anemometric method based on a new version of an aspirating probe. Measurements show that mixing is directly

M. Favre-Marinet; E. B. Camano Schettini

2001-01-01

17

Information Processing Potentials in Large-Scale Operations.  

National Technical Information Service (NTIS)

In the study of large organizations, the information, communication, and governing processes have been extremely difficult to formulate. Towards such a formulation, the strategy of the Leviathan studies has been to pursue two lines of attack--theoretical ...

B. K. Rome S. C. Rome

1966-01-01

18

Germination Responses to Water Potential in Neotropical Pioneers Suggest Large-seeded Species Take More Risks  

PubMed Central

Background and Aims In neotropical forests, very small-seeded pioneer species (<0·1 mg seed mass) recruit preferentially in small tree fall gaps and at gap edges, but large-seeded pioneers do not. Since water availability is related to gap size, these differences in microsite preference may reflect in part species-specific differences in germination at reduced water potentials. Methods For 14 neotropical pioneer species, the hypothesis is tested that small-seeded species, with shallow initial rooting depths, reduce the risks associated with desiccation by germinating more slowly and at higher water potentials than large-seeded species. Key Results Germination occurred both more quickly and at lower water potentials with increasing seed mass. For example, Ochroma pyramidale (seed mass 5·5 mg) had a time to 50 % germination (T50) of 2·8 d and a median base potential for germination (?b50) of ?1·8 MPa while Clidemia quinquenervia (seed mass 0·017 mg) had a T50 of 17·6 d and ?b50 of ?1·1 MPa. Conclusions These data suggest that small-seeded species germinate only in comparatively moist microsites, such as small canopy gaps, which may reduce the risk of drought-induced mortality. Conversely, large-seeded species are able to germinate in the drier environment of large gaps, where they benefit by enhanced seedling growth in a high irradiance environment. The positive association of seed size and canopy gap size for optimal seedling establishment is maintained by differential germination responses to soil water availability coupled with the scaling of radicle growth rate and seed size, which collectively confer greater drought tolerance on large-seeded species.

Daws, Matthew I.; Crabtree, Lora M.; Dalling, James W.; Mullins, Christopher E.; Burslem, David F. R. P.

2008-01-01

19

Peru onshore-deepwater basins should have large potential  

Microsoft Academic Search

Perupetro`s recent announcement that 13 offshore exploration blocks of nearly 1 million acres each will be offered for bids in the fourth quarter of 1998 has reawakened interest in this extensive, largely unexplored area. The new government policy, combined with the results of modern, deep-probing seismic surveys, has already led to a stepped-up search for oil and gas that will

F. Zuniga-Rivero; J. A. Keeling; H. Hay-Roe

1998-01-01

20

Zeta potential of different lithotypes in Shenfu coal  

Microsoft Academic Search

The zeta potential of different lithotypes of two coals with high content of inertinite in Shenfu Coalfield has been studied.\\u000a Moreover, the effects of pH value and the addition of surfactants and inorganic salts on zeta potential have also been discussed.\\u000a It has been concluded that the zero potential point (ZPP) of vitrain is between about 3.30 and 3.40 of

Xinqian Shu; Shuquan Zhu; Zuna Wang; Jingqiu Xu; Lingmei Ge

1997-01-01

21

A micropump based on water potential difference in plants  

Microsoft Academic Search

In land plants, water vapor diffuses into the air through the stomata. The loss of water vapor creates a water potential difference\\u000a between the leaf and the soil, which draws the water upward. Quantitatively, the water potential difference is 1–2 MPa which\\u000a can support a water column of 100–200 m. Here we present the design and operation of a biomimetic micropump. The

Jing Min Li; Chong Liu; Kai Ping Zhang; Xue Ke; Zheng Xu; Chun Yu Li; Li Ding Wang

22

Large Scale Predictions of Potential Post-fire Erosion  

NASA Astrophysics Data System (ADS)

High-severity wildfires are of increasing concern because of their potential for initiating flash floods and surface erosion, degrading water quality, and reducing reservoir capacity. In many areas fire suppression has increased fuel accumulations and hence the potential for high-severity wildfires. Land management agencies are undertaking programs to reduce fuel loadings and the associated risk of high-severity wildfires, but the areas needing treatment greatly exceed the available funding. It is therefore necessary to determine which areas should have a higher priority for such treatments. Similarly, when wildfires do occur there is an immediate need to determine which areas should have the highest priority for post-fire rehabilitation treatments. One criterion for allocating treatments is the potential risk of post-fire erosion, but to be effective this assessment needs to be carried out at a broad scale. This paper presents a procedure and initial results for predicting spatially-explicit, post-fire erosion risks at the hillslope scale for forest and shrub lands across the western U.S. Our approach utilizes existing physical models and datasets in a GIS framework. The model for predicting erosion is GeoWEPP, the Geographical interface for the Water Erosion Prediction Project (WEPP). The primary inputs for GeoWEPP include climate, topography, soils, and land cover/land use. Daily climate inputs were generated with Cligen, which is a stochastic weather generator distributed with WEPP. A 30-m digital elevation model, STATSGO-derived soils data, and vegetation cover were obtained from the U.S. Forest Service's LANDFIRE project. Since recent research has shown that percent ground cover is a dominant control on post-fire erosion rates, we generated a spatially-explicit map of post-fire ground cover by first using historic weather data to determine the 1000-hr fuel moisture values when fuel conditions were at 98-100% ERC (Energy Released Component). These fuel moisture values were fed into FOFEM (First Order Fire Effects Model) to obtain spatially-explicit predictions of percent ground cover, and this provided the additional land cover/land use information needed by GeoWEPP. The predicted erosion rates are comparable to measured values in the Colorado Front Range, but are much too high for the higher rainfall areas along the Pacific Coast. This pattern indicates that precipitation is having a pre-dominant effect on predicted post-fire erosion rates, especially in areas that are projected to burn at low severity. Hence the predicted erosion rates will be most useful in relative terms at the local and possibly regional scale, while comparisons between regions may be of more limited validity.

Miller, M. E.; MacDonald, L. H.

2005-12-01

23

Evaluation of potential runaway generation in large-tokamak disruptions  

SciTech Connect

A detailed evaluation of various potential mechanisms for the generation of strong runaway beams during disruptions of largetokamak devices, including TFTR, JET, DIIID and ITER, is performed based on typical operating parameters of these devices and the presently accepted disruption model. The main results include: (1) In the existing devices, the evaporative preicer'' process by itself can lead to sizable runaway beams in disruptions of high-current-medium-to-low-ne discharges. In ITER, such runaways are expected mainly for discharges with ne values sizably smaller than the projected typical ones. (2) Runaway generation also may occur during post-thermal-quench period through the untrapping of trapped hot-thermal electrons remaining from the pre-thermal-quench plasma; this process may be directly important in particular in disruptions of high-T[sub e] discharges with details depending on the time required for reclosure of the magnetic surfaces. Both processes (1) and (2) will occur and be completed mostly during the initial few 100 [mu]sec after the thermal quench. (3) Subsequently, close collisions of runaways with cold plasma electrons generally will lead to an exponential growth ( avalanching'') of runaway populations generated by processes (1) and/or (2) and/or others; this process will be effective in particular during the current quench phase and will continue until the resulting runaway beam will carry essentially all of the remaining discharge current. In presently existing devices, possible avalanche factors of up to 10[sup 2]--10[sup 5] may be expected; in ITER, avalanche factors of up to 10[sup 10]--10[sup 15] -- if not properly suppressed -- are expected to lead to strong runaway beams in most disruptions, except those at particularly high densities. At the same time, avalanching will shift the main part of their energy spectrum down to relatively low energies around 10--20 MeV, and may sizably change the spatial distribution of the runaways.

Fleischmann, H.H.; Zweben, S.J. (Princeton Univ., NJ (United States). Plasma Physics Lab. Cornell Univ., Ithaca, NY (United States). School of Applied and Engineering Physics)

1993-06-01

24

Adaptive differences in the body proportions of large felids.  

PubMed

Body proportions of eight species of large felids were studied and the relationship between their morphology, habitat structure and habitat utilization was analyzed. Both Panthera onca and Neofelis nebulosa are exclusive forest dwellers (found exclusively in high densly structured habitats). These felids have the relatively shortest anterior limbs and lumbar spine. In addition, P. onca has the relatively shortest posterior limbs of the large felids, while the posterior limbs of N. nebulosa are relatively long when compared with those of P. onca which seems to be an adaptation for jumping. All large fields use the anterior limbs to make primary contact with their prey. In addition, the prey taken by the forest fields can exceed their own body weight. On the other hand, the cheetah is found in low structured habitats (savanna), and it has the relatively longest limbs and lumbarspine of the large felids. But the cheetah's prey usually weigh less than its own body weight. The cheetah also employs a 'rapid pursuit phase' in hunting and is capable of overtaking its prey. The lion, however, was found to have the body proportions of a forest felid, yet it also resides in low structured habitats. It is postulated that the utilization of large prey by the lion limits the possibilities for morphological adaptations for speed. To increase hunting efficiency, reproductive success, and territorial defense on the plains, lions form prides. PMID:973541

Gonyea, W J

1976-01-01

25

Oxidation-reduction potentials of different chlorophylls in methanol  

Microsoft Academic Search

It was found that the reversible decolorisation of some chlorophylls upon the subsequent addition of ferric and ferrous salts, as originally measured by Rabinowtich and Weiss for chlorophyll a, proceeded at a reproducible oxidation-reduction potential.\\u000a\\u000aA marked difference was found to occur between the redox potentials of the bacterial pigments and those of the green plant pigments.\\u000a\\u000aApart from these

J. C. Goedheer; G. H. Horreus de Haas; P. Schuller

1958-01-01

26

Adaptive differences in the body proportions of large felids  

Microsoft Academic Search

Body proportions of eight species of large felids were studied and the relationship between their morphology, habitat structure and habitat utilization was analyzed. Both Panthera onca and Neofelis nebulosa are exclusive forest dwellers (found exclusively in high densly structured habitats). These felids have the relatively shortest anterior limbs and lumbar spine. In addition, P. onca has the relatively shortest posterior

William J. Gonyea

1976-01-01

27

Energetic recoils in UO2 simulated using five different potentials  

SciTech Connect

This report presents the results of classical molecular dynamics simulations of the diffuse pre-melting transition, melting, and defect production by 1 keV U recoils in UO2 using five different rigid-ion potentials. The experimentally-observed pre-melting transition occurred for all five cases. For all the potentials studied, dynamic defect annealing is highly effective and is accompanied by replacement events on the anion sublattice. The primary damage state after ~15 ps consists of isolated Frenkel pairs and interstitial and vacancy clusters of various sizes. The average displacement energy varies from ~28 to ~83 eV and the number of Frenkel pairs is different by a factor of three depending on the choice of potential. The size and spatial distribution of vacancy and interstitial clusters is drastically different for the potentials studied. The results provide statistics of defect production. They point to a pressing need to determine defect formation, migration and binding energies in UO2 from first principles and to develop reliable potentials based on this data for simulating microstructural evolution in nuclear fuel under operating conditions.

Devanathan, Ramaswami; Yu, Jianguo; Weber, William J.

2009-05-07

28

Comparison of different proximity potentials for asymmetric colliding nuclei  

NASA Astrophysics Data System (ADS)

Using the different versions of phenomenological proximity potential as well as other parametrizations within the proximity concept, we perform a detailed comparative study of fusion barriers for asymmetric colliding nuclei with asymmetry parameter as high as 0.23. In all, 12 different proximity potentials are robust against the experimental data of 60 reactions. Our detailed study reveals that the surface energy coefficient as well as radius of the colliding nuclei depend significantly on the asymmetry parameter. All models are able to explain the fusion barrier heights within ±10% on the average. The potentials due to Bass 80, AW 95, and Denisov DP explain nicely the fusion cross sections at above- as well as below-barrier energies.

Dutt, Ishwar; Puri, Rajeev K.

2010-06-01

29

Comparison of different proximity potentials for asymmetric colliding nuclei  

SciTech Connect

Using the different versions of phenomenological proximity potential as well as other parametrizations within the proximity concept, we perform a detailed comparative study of fusion barriers for asymmetric colliding nuclei with asymmetry parameter as high as 0.23. In all, 12 different proximity potentials are robust against the experimental data of 60 reactions. Our detailed study reveals that the surface energy coefficient as well as radius of the colliding nuclei depend significantly on the asymmetry parameter. All models are able to explain the fusion barrier heights within +-10% on the average. The potentials due to Bass 80, AW 95, and Denisov DP explain nicely the fusion cross sections at above- as well as below-barrier energies.

Dutt, Ishwar; Puri, Rajeev K. [Department of Physics, Panjab University, Chandigarh 160014 (India)

2010-06-15

30

New Feature Selection Algorithm based on Potential Difference  

Microsoft Academic Search

The new Potential Difference Algorithm for feature selection is a data pre-processing algorithm. Data preprocessing is one of the study topics in data mining. Normally, raw data is just a collection of nonsense numbers. The decision could not make based on the raw data. The algorithms related to data mining and data analysis need some pre-processed data. The quality of

Guangyuan Liu; Yu Liu; Liyan Dong; Senmiao Yuan; Yongli Li

2007-01-01

31

Gender Differences in Chemosensory Perception and Event-related Potentials  

Microsoft Academic Search

The present study investigated chemosensory gender differences by means of ratings of total nasal chemosensory intensity, unpleasantness and sensory irritation and simultaneous recordings of chemosensory event-related potentials (CSERPs) for three concentrations of the olfactory\\/trigeminal stimulus pyridine in 19 women and 17 men, all young adults. Results show that, compared to men, women gave higher intensity and unpleasantness ratings, in particular

Jonas K. Olofsson; Steven Nordin

2004-01-01

32

Abnormalities of nasal potential difference measurement in Liddle's syndrome.  

PubMed Central

In Liddle's syndrome, a rare inherited form of hypertension, epithelial sodium channel mutations appear to cause high blood pressure by increasing sodium reabsorption through sodium channels in the renal distal tubule. This increase in channel activity has not been confirmed previously by in vivo measurement. We have made transnasal potential difference measurements (effective in detection of increased sodium channel activity in cystic fibrosis) in three brothers with genetically proven Liddle's syndrome, their unaffected sister, and 40 normotensive controls. Maximum potential difference after 2 wk off treatment in the affected brothers was -30.4+/-1.2 mV (values mean+/-SD, lumen-negative with respect to submucosa) and was significantly more lumen-negative than that of the control group (-18.6+/-6.8 mV, P = 0.0228) or the unaffected sister (-18.25 mV, P < 0.01). The change in potential difference after topical application of 10(-)4 M amiloride was greater in the Liddle's patients, 14.0+/-2.1 mV, than in controls (7.9+/-3.9 mV, P = 0.0126) or the unaffected sister (5.5 mV, P < 0.05). This is the first in vivo demonstration of increased sodium channel activity in Liddle's syndrome. If these results are confirmed in other kindreds with this condition, then nasal potential difference measurements could provide a simple clinical test for Liddle's syndrome.

Baker, E; Jeunemaitre, X; Portal, A J; Grimbert, P; Markandu, N; Persu, A; Corvol, P; MacGregor, G

1998-01-01

33

GENDER DIFFERENCES IN ORGANIZATIONAL LEADERSHIP A Large Sample Study  

Microsoft Academic Search

In order to investigate possible gender differences in organizational leadership behavior, a diverse sample of North American male and female managers (n=1,800) matched for organization, management level, job function, and management experience were com- pared on 22 leadership behaviors and 3 effectiveness measures. Outcome measures were assessed using a 360-degree strategy in which each manager was evaluated by self, boss,

Robert I. Kabacoff

2010-01-01

34

Correlation of variations in intraluminal pressure and potential differences in the perfused colen.  

PubMed Central

To investigate the nature of variations in the large intestine potential differences, a continuous perfusion of isotonic saline was carried out in the colon of 14 rats. Intraluminal pressure and potential differences between the lumen and the peritoneal cavity were continuously and simultaneously recorded, while impedance of the system and respiration were also constantly monitored. To obtain a quantitative evaluation of the data, Fast Fouier Transform was performed on the signals and their derivatives which were auto- and cross-correlated. While there was no obvious relation between pressure and potential in the unperfused colon, there was clear visual qualirative evidence that, during steady state conditions of perfusion, an increase in intraluminal pressure was accompanied by a decrease in potential differences, while impedance of the recording system remained unchanged. Computer analysis disclosed four narrow ranges of stable frequencies for both pressure and potential. They were centred around 0-3, 1-75, 10-7, and 75 cycles per minute, the latter being synchronous with respiration. It is concluded that the variations of potential differences recorded during perfusion, a well-know phenomenon, are not electrical artefacts: the fast rhythm is probably induced by respiration, which increases intracolonic pressure and that, in turn, reduces the absolute value of potential differences, which remain negative mucosa versus serosa. The slower rhythms are synchronous for pressure and potential. Mechanisms responsible for the decrease in potential related to the increase in pressure remain unknown.

Postaire, J G; Gerard, J; Devroede, G; Van Houtte, N

1977-01-01

35

Injury differences between small and large overlap frontal crashes.  

PubMed

Because small overlap impacts have recently emerged as a crash mode posing great injury risk to occupants, a detailed analysis of US crash data was conducted using the NASS/CDS and CIREN databases. Frontal crashes were subcategorized into small overlap impact (SOI) and large overlap impact (LOI) using crash and crush characteristics from the datasets. Injuries to head, spine, chest, hip and pelvis, and lower extremities were parsed and compared between crash types. MAIS 3+ occupants in NASS/CDS and CIREN demonstrated increased incidence of head, chest, spine, and hip/pelvis injuries in SOI compared to LOI. In NASS/CDS, subgaleal hematoma represented 48.6% of SOI head injury codes but 27.6% in LOI. Cervical spine posterior element fractures also represented greater proportions of SOI spine injuries (e.g., facet fractures: 27.8 vs. 14.0%), and proximal femur fractures represented a greater proportion of hip/pelvis injuries (e.g., intertrochanteric fracture: 32.5 vs. 11.8%). Tarsal/metatarsal fractures were a lesser proportion of lower extremity injuries in SOI compared to LOI. Occupant contact points inducing these injuries were observed in CIREN cases in some instances without compartment intrusion. These injuries suggest the substantial role of occupant kinematics in SOI which may induce suboptimal occupant restraint interaction. PMID:22105392

Hallman, Jason J; Yoganandan, Narayan; Pintar, Frank A; Maiman, Dennis J

2011-01-01

36

Separation of large mammalian ventricular myosin differing in ATPase activity.  

PubMed

To investigate a possible heterogeneity of human ventricular myosin, papillary muscles of patients with valvular dysfunction were examined using a modified native gel electrophoresis. Myosin was separated into 2 components termed VA and VB, whereby the VA to VB proportion appeared to depend on the ventricular load. The proportion of the faster migrating band VA was correlated (P<0.05) with end-diastolic pressure and the aortic pressure-cardiac index product. The regression based on these variables accounted for 67% of the variation in VA (R2=0.67). The VA proportion was, however, not significantly correlated with cardiac norepinephrine concentration. The ATPase activity of the 2 components of myosin was assessed from the Ca3(PO4)2 precipitation by incubating the gel in the presence of ATP and CaCl2. The ATPase activity of VA was 60% of that of VB. The VA and VB forms were observed also in the cat (31.4% VA), dog (32.1% VA), pig (28.5% VA), wild pig (33.7% VA), and roe deer (30.5% VA). VA and VB were not detected in the rat exhibiting the 3 isoforms V1, V2, and V3, rabbit (100% V3), and hare (86% V1). The data demonstrate a heterogeneity of large mammalian ventricular myosin, whereby an increased cardiac load appeared to be associated with a higher myosin VA proportion that exhibited a reduced ATPase activity. PMID:17612641

Rupp, Heinz; Maisch, Bernhard

37

Injury Differences Between Small and Large Overlap Frontal Crashes  

PubMed Central

Because small overlap impacts have recently emerged as a crash mode posing great injury risk to occupants, a detailed analysis of US crash data was conducted using the NASS/CDS and CIREN databases. Frontal crashes were subcategorized into small overlap impact (SOI) and large overlap impact (LOI) using crash and crush characteristics from the datasets. Injuries to head, spine, chest, hip and pelvis, and lower extremities were parsed and compared between crash types. MAIS 3+ occupants in NASS/CDS and CIREN demonstrated increased incidence of head, chest, spine, and hip/pelvis injuries in SOI compared to LOI. In NASS/CDS, subgaleal hematoma represented 48.6% of SOI head injury codes but 27.6% in LOI. Cervical spine posterior element fractures also represented greater proportions of SOI spine injuries (e.g., facet fractures: 27.8 vs. 14.0%), and proximal femur fractures represented a greater proportion of hip/pelvis injuries (e.g., intertrochanteric fracture: 32.5 vs. 11.8%). Tarsal/metatarsal fractures were a lesser proportion of lower extremity injuries in SOI compared to LOI. Occupant contact points inducing these injuries were observed in CIREN cases in some instances without compartment intrusion. These injuries suggest the substantial role of occupant kinematics in SOI which may induce suboptimal occupant restraint interaction.

Hallman, Jason J.; Yoganandan, Narayan; Pintar, Frank A.; Maiman, Dennis J.

2011-01-01

38

Antioxidant potential of different plum cultivars during storage.  

PubMed

Plums, the most commonly consumed fruits from Romania, are fruits rich in bioactive compounds, such as antioxidants. This research work was carried out to investigate the antioxidant potential of twelve plum cultivars, fresh and stored during 10days at 4°C by using different methods (DPPH, ORAC and erythrocyte resistance to haemolysis). The contents of total phenolic compounds and total anthocyanins were also determined by specific spectrometric methods. Significant differences between fresh and stored plum cultivars (p<0.05) were found. Storage at 4°C resulted in an increase in antioxidant potential and anthocyanins content of the autumn plum varieties. Autumn plum varieties also showed a higher antioxidant capacity than summer varieties, as assessed by the ORAC and the haemolysis resistance assays. Our results suggest that, even after storage, plums could be a good source of antioxidants, which may provide health-promoting effects for humans. PMID:24176372

Mihalache Arion, Cristina; Tabart, Jessica; Kevers, Claire; Niculaua, Marius; Filimon, R?zvan; Beceanu, Dumitru; Dommes, Jacques

2013-09-20

39

Acylglycerol structure of peanut oils of different atherogenic potential  

Microsoft Academic Search

Detailed investigation was made of the triacylglycerol structure of native, simulated, and interesterified peanut oils, which\\u000a had previously been shown to differ markedly in their atherogenic potential. By means of chromatographic and stereospecific\\u000a analyses, it was shown that the more atherogenic native oil contains a significantly greater proportion of triacylglycerols\\u000a with linoleic insn-2-position and arachidic, behenic, and lignoceric acids insn-3-position

J. J. Myher; L. Marai; A. Kuksis; D. Kritchevsky

1977-01-01

40

Gastric Transmucosal Potential Difference: Effect of Antisecretory and Gastroprotective Drugs  

Microsoft Academic Search

1.Ion transport and electrical resistance of the gastric mucosa are responsible for the generation of the transmucosal potential difference (PD), which is considered an index of mucosal integrity.2.The aim of the present work was to study the effect of some antisecretory and gastroprotective agents on PD in stomachs damaged by ethanol.3.Control PD values measured in anesthetized rats were 35 to

Viera Nosál'ová; Anna Babul'ová; Viktor Bauer

1998-01-01

41

OBTAINING POTENTIAL FIELD SOLUTIONS WITH SPHERICAL HARMONICS AND FINITE DIFFERENCES  

SciTech Connect

Potential magnetic field solutions can be obtained based on the synoptic magnetograms of the Sun. Traditionally, a spherical harmonics decomposition of the magnetogram is used to construct the current- and divergence-free magnetic field solution. This method works reasonably well when the order of spherical harmonics is limited to be small relative to the resolution of the magnetogram, although some artifacts, such as ringing, can arise around sharp features. When the number of spherical harmonics is increased, however, using the raw magnetogram data given on a grid that is uniform in the sine of the latitude coordinate can result in inaccurate and unreliable results, especially in the polar regions close to the Sun. We discuss here two approaches that can mitigate or completely avoid these problems: (1) remeshing the magnetogram onto a grid with uniform resolution in latitude and limiting the highest order of the spherical harmonics to the anti-alias limit; (2) using an iterative finite difference algorithm to solve for the potential field. The naive and the improved numerical solutions are compared for actual magnetograms and the differences are found to be rather dramatic. We made our new Finite Difference Iterative Potential-field Solver (FDIPS) a publicly available code so that other researchers can also use it as an alternative to the spherical harmonics approach.

Toth, Gabor; Van der Holst, Bart; Huang Zhenguang [Center for Space Environment Modeling, University of Michigan, Ann Arbor, MI 48109 (United States)

2011-05-10

42

Collision between immiscible drops with large surface tension difference  

NASA Astrophysics Data System (ADS)

Immiscible drop collision, as occurring in fuel-oxidizer sprays or in the release of certain fire-extinguishing agents, tends to exhibit a much richer behavior with respect to miscible drops collision thanks to the formation of a liquid-liquid interface during impact. For instance, in near-head-on diesel-water drop collisions, ``overlaying'' may occur in which the diesel oil flows from the collision point around the water drop to gather at the opposite location of the drop. To simulate this class of multi-material flows, the combined volume-of-fluid / level set methodology that sharply captures a single liquid-gas interface (Sussman et al, J. of Comp. Phys., 2007) needs to be duplicated for a second, independent interface. In this presentation, we will show that simulation results are not affected by the reconstruction order of the interfaces, as in other surface capturing methods. We will also propose different numerical solutions to treat surface tension in the triple point computational cells, and examine the characteristics of the flow developing at the contact line between the two liquids and air in overlaying head-on collisions.

Arienti, Marco; Li, Xiaoyi; Soteriou, Marios; Sussman, Mark

2009-11-01

43

The radiative forcing potential of different climate geoengineering options  

NASA Astrophysics Data System (ADS)

Climate geoengineering proposals seek to rectify the Earth's current and potential future radiative imbalance, either by reducing the absorption of incoming solar (shortwave) radiation, or by removing CO2 from the atmosphere and transferring it to long-lived reservoirs, thus increasing outgoing longwave radiation. A fundamental criterion for evaluating geoengineering options is their climate cooling effectiveness, which we quantify here in terms of radiative forcing potential. We use a simple analytical approach, based on energy balance considerations and pulse response functions for the decay of CO2 perturbations. This aids transparency compared to calculations with complex numerical models, but is not intended to be definitive. It allows us to compare the relative effectiveness of a range of proposals. We consider geoengineering options as additional to large reductions in CO2 emissions. By 2050, some land carbon cycle geoengineering options could be of comparable magnitude to mitigation "wedges", but only stratospheric aerosol injections, albedo enhancement of marine stratocumulus clouds, or sunshades in space have the potential to cool the climate back toward its pre-industrial state. Strong mitigation, combined with global-scale air capture and storage, afforestation, and bio-char production, i.e. enhanced CO2 sinks, might be able to bring CO2 back to its pre-industrial level by 2100, thus removing the need for other geoengineering. Alternatively, strong mitigation stabilising CO2 at 500 ppm, combined with geoengineered increases in the albedo of marine stratiform clouds, grasslands, croplands and human settlements might achieve a patchy cancellation of radiative forcing. Ocean fertilisation options are only worthwhile if sustained on a millennial timescale and phosphorus addition may have greater long-term potential than iron or nitrogen fertilisation. Enhancing ocean upwelling or downwelling have trivial effects on any meaningful timescale. Our approach provides a common framework for the evaluation of climate geoengineering proposals, and our results should help inform the prioritisation of further research into them.

Lenton, T. M.; Vaughan, N. E.

2009-08-01

44

Potential theory for shock reflection by a large-angle wedge  

PubMed Central

When a plane shock hits a wedge head on, it experiences a reflection, and then a self-similar reflected shock moves outward as the original shock moves forward in time. Experimental, computational, and asymptotic analysis has shown that various patterns of reflected shocks may occur, including regular and Mach reflection. However, most fundamental issues for shock reflection phenomena have not been understood, such as the transition among the different patterns of shock reflection; therefore, it is essential to establish a global existence and stability theory for shock reflection. On the other hand, there has been no rigorous mathematical result on the global existence and stability of solutions to shock reflection, especially for potential flow, which has widely been used in aerodynamics. The theoretical problems involve several challenging difficulties in the analysis of nonlinear partial differential equations including elliptic-hyperbolic mixed type, free-boundary problems, and corner singularity, especially when an elliptic degenerate curve meets a free boundary. Here we develop a potential theory to overcome these difficulties and to establish the global existence and stability of solutions to shock reflection by a large-angle wedge for potential flow. The techniques and ideas developed will be useful to other nonlinear problems involving similar difficulties.

Chen, Gui-Qiang; Feldman, Mikhail

2005-01-01

45

Resolving the Difference in Electric Potential within a Charged Macromolecule  

NASA Astrophysics Data System (ADS)

The difference of the electric potential between the middle and end of polystyrene sulfonate (PSS-) chain is discovered experimentally. Using a pH-responsive fluorophore attached to these two locations on the PSS- chain, the local pH value was determined by single molecule fluorescence technique: photon counting histogram (PCH). By the observation of a very high accumulation of proton (2-3 orders of magnitude in concentration) at the vicinity of the PSS- as the result of the electrostatic attraction between the charged chain and protons, the electric potential of the PSS- chain is determined. A higher extent of counterion adsorption is discovered at the middle of the PSS- chain than the chain end. The entropy effect of the counterion adsorption is also discovered - upon the dilution of protons, previously adsorbed counterions are detached from the chain.

Luo, Shuangjiang; Yang, Jingfa; Zhao, Jiang

2013-03-01

46

Comparing different coarse-grained potentials for star polymers.  

PubMed

We compare different coarse-grained single-blob models for star polymers. We find that phenomenological models inspired by the Daoud-Cotton theory reproduce quite poorly the thermodynamics of these systems, even if the potential is assumed to be density dependent, as done in the analysis of experimental results. Using the numerically determined coarse-grained potential, we also determine the minimum value f(c) of the functionality of the star polymer for which a fluid-solid transition occurs. By applying the Hansen-Verlet criterion we find 35 < f(c) ? 40. This result is confirmed by an analysis that uses the modified (reference) hypernetted chain method and is qualitatively consistent with previous work. PMID:23556746

Menichetti, Roberto; Pelissetto, Andrea

2013-03-28

47

Comparing different coarse-grained potentials for star polymers  

NASA Astrophysics Data System (ADS)

We compare different coarse-grained single-blob models for star polymers. We find that phenomenological models inspired by the Daoud-Cotton theory reproduce quite poorly the thermodynamics of these systems, even if the potential is assumed to be density dependent, as done in the analysis of experimental results. Using the numerically determined coarse-grained potential, we also determine the minimum value fc of the functionality of the star polymer for which a fluid-solid transition occurs. By applying the Hansen-Verlet criterion we find 35 < fc <~ 40. This result is confirmed by an analysis that uses the modified (reference) hypernetted chain method and is qualitatively consistent with previous work.

Menichetti, Roberto; Pelissetto, Andrea

2013-03-01

48

Magnetopause Shape and Polar Cap Potential Under Large Solar Wind Dynamic Pressure  

NASA Astrophysics Data System (ADS)

We use three-dimensional MHD (magnetohydrodynamics) simulations to study the shape of the day side magnetopause under conditions of relatively large solar wind dynamic pressure (around or above 10nPa). Our MHD code is a finite-difference code accurate to second order in space and time and solves the MHD equations on a spherical coordinate grid. We produce a simulated magnetosphere by running the code in constant solar wind conditions and allow the solution to asymptotically approach a near-constant solution. The magnetopause shape is determined by locating the last closed field lines in the GSE x-y plane at various azimuthal angles. The subsolar radius of the magnetopause agrees well with published models. More extensive details on the shape of the magnetopause off the subsolar line will be reported. From the extent of the magnetopause on the equatorial flanks, we also estimate the dawn-to-dusk electric field potential across the magnetopause.

Cable, S.; Lin, C. S.

2007-12-01

49

The radiative forcing potential of different climate geoengineering options  

NASA Astrophysics Data System (ADS)

Climate geoengineering proposals seek to rectify the Earth's current radiative imbalance, either by reducing the absorption of incoming solar (shortwave) radiation, or by removing CO2 from the atmosphere and transferring it to long-lived reservoirs, thus increasing outgoing longwave radiation. A fundamental criterion for evaluating geoengineering options is their climate cooling effectiveness, which we quantify here in terms of radiative forcing potential. We use a simple analytical approach, based on the global energy balance and pulse response functions for the decay of CO2 perturbations. This aids transparency compared to calculations with complex numerical models, but is not intended to be definitive. Already it reveals some significant errors in existing calculations, and it allows us to compare the relative effectiveness of a range of proposals. By 2050, only stratospheric aerosol injections or sunshades in space have the potential to cool the climate back toward its pre-industrial state, but some land carbon cycle geoengineering options are of comparable magnitude to mitigation "wedges". Strong mitigation, i.e. large reductions in CO2 emissions, combined with global-scale air capture and storage, afforestation, and bio-char production, i.e. enhanced CO2 sinks, might be able to bring CO2 back to its pre-industrial level by 2100, thus removing the need for other geoengineering. Alternatively, strong mitigation stabilising CO2 at 500 ppm, combined with geoengineered increases in the albedo of marine stratiform clouds, grasslands, croplands and human settlements might achieve a patchy cancellation of radiative forcing. Ocean fertilisation options are only worthwhile if sustained on a millennial timescale and phosphorus addition probably has greater long-term potential than iron or nitrogen fertilisation. Enhancing ocean upwelling or downwelling have trivial effects on any meaningful timescale. Our approach provides a common framework for the evaluation of climate geoengineering proposals, and our results should help inform the prioritisation of further research into them.

Lenton, T. M.; Vaughan, N. E.

2009-01-01

50

Effect of large ion angular momentum spread and high current on inertial electrostatic confinement potential structures  

Microsoft Academic Search

Prior inertial electrostatic confinement (IEC) studies have assumed that very low angular momentum (zero in the ideal case) is necessary to achieve a potential well structure capable of trapping energetic ions in the center of a spherical device. However, the present study shows that high-current ion beams having large-angular-momentum spread can also form deep potential well traps

Ivon V. Tzonev; John M. DeMora; George H. Miley

1995-01-01

51

Pre-anthesis ovary development determines genotypic differences in potential kernel weight in sorghum.  

PubMed

Kernel weight is an important factor determining grain yield and nutritional quality in sorghum, yet the developmental processes underlying the genotypic differences in potential kernel weight remain unclear. The aim of this study was to determine the stage in development at which genetic effects on potential kernel weight were realized, and to investigate the developmental mechanisms by which potential kernel weight is controlled in sorghum. Kernel development was studied in two field experiments with five genotypes known to differ in kernel weight at maturity. Pre-fertilization floret and ovary development was examined and post-fertilization kernel-filling characteristics were analysed. Large kernels had a higher rate of kernel filling and contained more endosperm cells and starch granules than normal-sized kernels. Genotypic differences in kernel development appeared before stamen primordia initiation in the developing florets, with sessile spikelets of large-seeded genotypes having larger floret apical meristems than normal-seeded genotypes. At anthesis, the ovaries for large-sized kernels were larger in volume, with more cells per layer and more vascular bundles in the ovary wall. Across experiments and genotypes, there was a significant positive correlation between kernel dry weight at maturity and ovary volume at anthesis. Genotypic effects on meristem size, ovary volume, and kernel weight were all consistent with additive genetic control, suggesting that they were causally related. The pre-fertilization genetic control of kernel weight probably operated through the developing pericarp, which is derived from the ovary wall and potentially constrains kernel expansion. PMID:19228817

Yang, Zongjian; van Oosterom, Erik J; Jordan, David R; Hammer, Graeme L

2009-02-19

52

Pre-anthesis ovary development determines genotypic differences in potential kernel weight in sorghum  

PubMed Central

Kernel weight is an important factor determining grain yield and nutritional quality in sorghum, yet the developmental processes underlying the genotypic differences in potential kernel weight remain unclear. The aim of this study was to determine the stage in development at which genetic effects on potential kernel weight were realized, and to investigate the developmental mechanisms by which potential kernel weight is controlled in sorghum. Kernel development was studied in two field experiments with five genotypes known to differ in kernel weight at maturity. Pre-fertilization floret and ovary development was examined and post-fertilization kernel-filling characteristics were analysed. Large kernels had a higher rate of kernel filling and contained more endosperm cells and starch granules than normal-sized kernels. Genotypic differences in kernel development appeared before stamen primordia initiation in the developing florets, with sessile spikelets of large-seeded genotypes having larger floret apical meristems than normal-seeded genotypes. At anthesis, the ovaries for large-sized kernels were larger in volume, with more cells per layer and more vascular bundles in the ovary wall. Across experiments and genotypes, there was a significant positive correlation between kernel dry weight at maturity and ovary volume at anthesis. Genotypic effects on meristem size, ovary volume, and kernel weight were all consistent with additive genetic control, suggesting that they were causally related. The pre-fertilization genetic control of kernel weight probably operated through the developing pericarp, which is derived from the ovary wall and potentially constrains kernel expansion.

Yang, Zongjian; van Oosterom, Erik J.; Jordan, David R.; Hammer, Graeme L.

2009-01-01

53

Ultracold inelastic three-body collision rates for different two-body potentials with identical spectra  

NASA Astrophysics Data System (ADS)

We present a computational study of the way in which three-body observables differ for systems with identical two-body bound state energies and phase shifts. Using standard techniques arising from supersymmetric quantum mechanics [1], we construct a two-body potential with identical phase shifts, but different numbers of bound states. We consider model potentials with masses corresponding to Yb+Yb+H as an example. The mass ratio between Yb and H makes the computation much simpler. We scan through a large range of the two-body scattering length (identical for each potential) and note the differences in three-body loss rates. [4pt] [1] D. Baye and J. M. Sparenberg, Phys. Rev. Lett. 73, 2789-2792 (1994)

Meyer, Edmund; Esry, Brett

2011-06-01

54

Ocular Vestibular Evoked Myogenic Potential Using Different Test Stimuli  

PubMed Central

Aim. Ocular Evoked Myogenic Potential (oVEMP) are short latency potentials evoked by higher acoustic stimulation. In this study, we aimed at comparing the click, 500?Hz mixed modulated, and 500?Hz short duration tone burst stimuli using oVEMP. Material. Click, 500?Hz mixed modulated and 500?Hz short duration tone burst stimuli were used for the study. Method. Conventional sampling and conveneint study design were used. Sixty healthy subjects underwent contralateral oVEMP testing maintaining 30 degrees upward gaze. Single channel electrode montage was applied to record oVEMP response. Results. On statistical analysis the three stimuli evoked equal response rates (100%), and when latency of n1 and p1 and peak-peak amplitude were compared, the click evoked showed significantly early latency and lower peak-peak amplitude than the 500?Hz stimuli. Five hundred Hz stimuli did not show significant difference in latency and peak-peak amplitude of n1-p1. Discussion. Thus, 500?Hz stimuli can evoke better latency and peak-peak amplitude. oVEMP has good clinical significance in diagnosing subjects with vestibular dysfunction. To add to the sensitivity of the oVEMP test, 500?Hz stimuli may also be used as it can evoke better oVEMP responses in clinical population with good morphology.

Deepak, Dessai Teja; Bhat, Jayashree S.; Kumar, Kaushlendra

2013-01-01

55

Segregation distortion causes large-scale differences between male and female genomes in hybrid ants  

PubMed Central

Hybridization in isolated populations can lead either to hybrid breakdown and extinction or in some cases to speciation. The basis of hybrid breakdown lies in genetic incompatibilities between diverged genomes. In social Hymenoptera, the consequences of hybridization can differ from those in other animals because of haplodiploidy and sociality. Selection pressures differ between sexes because males are haploid and females are diploid. Furthermore, sociality and group living may allow survival of hybrid genotypes. We show that hybridization in Formica ants has resulted in a stable situation in which the males form two highly divergent gene pools whereas all the females are hybrids. This causes an exceptional situation with large-scale differences between male and female genomes. The genotype differences indicate strong transmission ratio distortion depending on offspring sex, whereby the mother transmits some alleles exclusively to her daughters and other alleles exclusively to her sons. The genetic differences between the sexes and the apparent lack of multilocus hybrid genotypes in males can be explained by recessive incompatibilities which cause the elimination of hybrid males because of their haploid genome. Alternatively, differentiation between sexes could be created by prezygotic segregation into male-forming and female-forming gametes in diploid females. Differentiation between sexes is stable and maintained throughout generations. The present study shows a unique outcome of hybridization and demonstrates that hybridization has the potential of generating evolutionary novelties in animals.

Kulmuni, Jonna; Seifert, Bernhard; Pamilo, Pekka

2010-01-01

56

Inventory studies of hydroelectric power plants: the methodological differences for small and large power plants.  

National Technical Information Service (NTIS)

The hydroelectric potential handbook produced by ELETROBRAS provides procedures to guides the hydro power studies of river sites. In this paper, a critical analysis of these procedures is carried out, for both large and small hydro power plants, pin point...

S. V. Bajay C. B. Martinez

1991-01-01

57

Redox potential difference between Desulfovibrio vulgaris and Clostridium beijerinckii flavodoxins.  

PubMed

The redox potential of the flavin mononucleotide (FMN) hydroquinones for one-electron reduction in the Desulfovibrio vulgaris ( D. vulgaris) flavodoxin ( E sq/hq for FMNH (*)/FMNH (-)) was calculated using the crystal structure of the relevant hydroquinone form and compared to the results of the Clostridium beijerinckii ( C. beijerinckii) flavodoxin. In D. vulgaris and C. beijerinckii flavodoxins, the protein side chain causes significant downshifts of 170 and 240 mV in E sq/hq, respectively. In the C. beijerinckii flavodoxin, the E sq/hq downshift because of the protein side chain is essentially compensated by the counter influence of the protein backbone ( E sq/hq upshift of 260 mV). However, in the D. vulgaris flavodoxin, the corresponding protein backbone influence on E sq/hq is significantly small, i.e., less than half of that in the C. beijerinckii flavodoxin. In particular, there is a significant difference in the influence of the protein backbone of the so-called 60s loop region between the two flavodoxins. The E sq/hq difference can be best explained by the lower compensation of the side chain influence by the backbone influence in the D. vulgaris flavodoxin than in the C. beijerinckii flavodoxin. PMID:18355044

Ishikita, Hiroshi

2008-03-21

58

An International Randomized Multicenter Comparison of Nasal Potential Difference Techniques  

PubMed Central

Background: The transepithelial nasal potential difference (NPD) is used to assess cystic fibrosis transmembrane conductance regulator (CFTR) activity. Unreliability, excessive artifacts, and lack of standardization of current testing systems can compromise its use as a diagnostic test and outcome measure for clinical trials. Methods: To determine whether a nonperfusing (agar gel) nasal catheter for NPD measurement is more reliable and less susceptible to artifacts than a continuously perfusing nasal catheter, we performed a multicenter, randomized, crossover trial comparing a standardized NPD protocol using an agar nasal catheter with the same protocol using a continuously perfusing catheter. The data capture technique was identical in both protocols. A total of 26 normal adult subjects underwent NPD testing at six different centers. Results: Artifact frequency was reduced by 75% (P < .001), and duration was less pronounced using the agar catheter. The measurement of sodium conductance was similar between the two catheter methods, but the agar catheter demonstrated significantly greater CFTR-dependent hyperpolarization, because ? zero Cl- + isoproterenol measurements were significantly more hyperpolarized with the agar catheter (224.2 ± 12.9 mV with agar vs 18.2 ± 9.1 mV with perfusion, P < .05). Conclusions: The agar nasal catheter approach demonstrates superior reliability compared with the perfusion nasal catheter method for measurement of NPD. This nonperfusion catheter method should be considered for adoption as a standardized protocol to monitor CFTR activity in clinical trials.

Solomon, George M.; Konstan, Michael W.; Wilschanski, Michael; Billings, Joanne; Sermet-Gaudelus, Isabelle; Accurso, Frank; Vermeulen, Francois; Levin, Elina; Hathorne, Heather; Reeves, Ginger; Sabbatini, Gina; Hill, Aubrey; Mayer-Hamblett, Nicole; Ashlock, Melissa; Clancy, John Paul

2010-01-01

59

[Frontal evoked potentials and sensitivity to methylphenidate. Individual differences].  

PubMed

Auditory evoked potentials (AEPs) were recorded from 2 sites (Cz and Fz) on 17 subjects while awake. Five sound intensities were used (40-50-60-70-80 dB). Regression slopes relating AEP amplitude (N1-P2 component) to stimulus intensity were used to describe augmentation or reduction (A/R) of amplitude with increasing intensity. The individual differences thereby obtained have been related with the individual responsiveness to methylphenidate (MPD) measured by the modifications of polygraphic sleep parameters after absorption of this substance. The sleep parameters were recorded under 3 conditions: N1, night of habituation; N2, reference night (placebo); N3, night after 20 mg of methylphenidate (MPD); nights 2 and 3 consisted of a double blind cross-over. For the placebo condition, the lower the A/R slope while awake (and particularly the Fz slope), the higher the sleep efficiency, with scarcity of nocturnal awakening and precocity of the morning awakening. Individual differences concerning MPD responsiveness measured with sleep parameter modifications are significantly correlated with the frontal A/R slopes: the wakefulness effect of MPD increases as the frontal A/R slope weakens while a paradoxal drowsiness effect is observed at the other extreme (frontal augmenters). Moreover, sleep modifications due to the first night effect show similarities with those due to MPD and are correlated in the same way with frontal A/R slopes. PMID:6463312

Bruneau, N; Laffont, F; Roux, S; Autret, A; Cathala, H P

1984-06-01

60

Assessment of economically optimal water management and geospatial potential for large-scale water storage  

NASA Astrophysics Data System (ADS)

Assessment of economically optimal water management and geospatial potential for large-scale water storage Weerasinghe, Harshi; Schneider, Uwe A Water is an essential but limited and vulnerable resource for all socio-economic development and for maintaining healthy ecosystems. Water scarcity accelerated due to population expansion, improved living standards, and rapid growth in economic activities, has profound environmental and social implications. These include severe environmental degradation, declining groundwater levels, and increasing problems of water conflicts. Water scarcity is predicted to be one of the key factors limiting development in the 21st century. Climate scientists have projected spatial and temporal changes in precipitation and changes in the probability of intense floods and droughts in the future. As scarcity of accessible and usable water increases, demand for efficient water management and adaptation strategies increases as well. Addressing water scarcity requires an intersectoral and multidisciplinary approach in managing water resources. This would in return safeguard the social welfare and the economical benefit to be at their optimal balance without compromising the sustainability of ecosystems. This paper presents a geographically explicit method to assess the potential for water storage with reservoirs and a dynamic model that identifies the dimensions and material requirements under an economically optimal water management plan. The methodology is applied to the Elbe and Nile river basins. Input data for geospatial analysis at watershed level are taken from global data repositories and include data on elevation, rainfall, soil texture, soil depth, drainage, land use and land cover; which are then downscaled to 1km spatial resolution. Runoff potential for different combinations of land use and hydraulic soil groups and for mean annual precipitation levels are derived by the SCS-CN method. Using the overlay and decision tree algorithms in GIS, potential water storage sites are identified for constructing regional reservoirs. Subsequently, sites are prioritized based on runoff generation potential (m3 per unit area), and geographical suitability for constructing storage structures. The results from the spatial analysis are used as input for the optimization model. Allocation of resources and appropriate dimension for dams and associated structures are identified using the optimization model. The model evaluates the capability of alternative reservoirs for cost-efficient water management. The Geographic Information System is used to store, analyze, and integrate spatially explicit and non-spatial attribute information whereas the algebraic modeling platform is used to develop the dynamic optimization model. The results of this methodology are validated over space against satellite remote sensing data and existing data on reservoir capacities and runoff. The method is suitable for application of on-farm water storage structures, water distribution networks, and moisture conservation structures in a global context.

Weerasinghe, Harshi; Schneider, Uwe A.

2010-05-01

61

Reduction of the field-aligned potential drop in the polar cap during large geomagnetic storms  

NASA Astrophysics Data System (ADS)

We have studied photoelectron flows and the inferred field-aligned potential drop in the polar cap during five large geomagnetic storms, which occurred in the periods when the photoelectron observations in the polar cap are available near the apogee of the Fast Auroral SnapshoT satellite (~4000 km) at solar maximum, and the footprint of the satellite paths in the polar cap was under sunlit conditions most of the time. In contrast to the ~20 V potential drop during geomagnetically quiet periods at solar maximum identified by Kitamura et al. (2012), the field-aligned potential drop frequently became smaller than ~5 V during the main and early recovery phases of the large geomagnetic storms. This result indicates that the acceleration of ions by a field-aligned potential drop in the polar cap and the lobe region is smaller during the main and early recovery phases of large geomagnetic storms compared to during geomagnetically quiet periods. Since ions with large flux originating from the cusp/cleft ionosphere convect into the polar cap during geomagnetic storms, the net escaping electron number flux should increase to balance the enhanced ion outflows under small field-aligned current conditions. The magnitude of the field-aligned potential drop would be reduced to let larger part of photoelectrons escape.

Kitamura, N.; Seki, K.; Nishimura, Y.; Hori, T.; Terada, N.; Ono, T.; Strangeway, R. J.

2013-08-01

62

Influence of perfusate temperature on nasal potential difference.  

PubMed

Nasal potential difference (NPD) quantifies abnormal ion transport in cystic fibrosis. It has gained acceptance as an outcome measure for the investigation of new therapies. To quantify the effect of solution temperature on NPD, we first examined the effect of switching from room temperature (20-25°C) to warmed (32-37°C) solutions and vice versa during each perfusion step. Secondly, standard protocols were repeated at both temperatures in the same subjects. Changing solution temperature did not alter NPD during perfusion with Ringer's solution (<1 mV) (p>0.1). During perfusion with zero chloride solution, changing from room temperature to warmed solutions tended to decrease absolute NPD (i.e. it became less negative) by 0.9 mV (p>0.1); changing from warmed to room temperature increased NPD by 2.1 mV (p<0.05). During isoprenaline perfusion, changing from room temperature to warmed solutions increased NPD by 1.5 mV (p<0.01) and from warmed to room temperature decreased NPD by 1.4 mV (p<0.05). For full protocols at room temperature or warmed in the same subjects, mean values were similar (n = 24). During warmed perfusion, group results for total chloride response had a larger standard deviation. As this increased variability will probably decrease the power of trials, this study suggests that solutions at room temperature should be recommended for the measurement of NPD. PMID:23100510

Bronsveld, Inez; Vermeulen, François; Sands, Dorotha; Leal, Teresinha; Leonard, Anissa; Melotti, Paola; Yaakov, Yasmin; de Nooijer, Roel; De Boeck, Kris; Sermet, Isabelle; Wilschanski, Michael; Middleton, Peter G

2012-10-25

63

Identifying potential environmental impacts of large-scale deployment of dedicated bioenergy crops in the UK  

Microsoft Academic Search

There is momentum, globally, to increase the use of plant biomass for the production of heat, power and liquid transport fuels. This review assesses the evidence base for potential impacts of large-scale bioenergy crop deployment principally within the UK context, but with wider implications for Europe, the USA and elsewhere. We focus on second generation, dedicated lignocellulosic crops, but where

Rebecca L. Rowe; Gail Taylor

2009-01-01

64

Potential of large-scale algal culture for biomass and lipid production in arid lands  

Microsoft Academic Search

The applicability of large-scale algal culture was examined to alleviate food-protein shortages, fossil fuel price increases, pollution of waters, soils, and the atmosphere by direct and indirect human activities. The main effort was to examine the potential use of microalgae as a source of lipids. It was concluded that: (1) algal mass culture may be economically competitive with other land

Z. Dubinsky; T. Berner; S. Aaronson

1978-01-01

65

NYU researchers identify new potential therapeutic target for diffuse large B-cell lymphoma:  

Cancer.gov

Researchers from the NYU Cancer Institute, an NCI-designated cancer center at NYU Langone Medical Center, have discovered a new potential therapeutic target for Diffuse Large B-Cell Lymphoma (DLBCL), the most aggressive and common type of lymphoma in adults. The new study, published in the November 23 issue of Nature, reveals the underlying molecular mechanism contributing to the development of lymphomagenesis.

66

Gender differences, polypharmacy, and potential pharmacological interactions in the elderly  

PubMed Central

OBJECTIVE: This study aims to analyze pharmacological interactions among drugs taken by elderly patients and their age and gender differences in a population from Porto Alegre, Brazil. METHODS: We retrospectively analyzed the database provided by the Institute of Geriatric and Gerontology, Porto Alegre, Brazil. The database was composed of 438 elderly and includes information about the patients' disease, therapy regimens, utilized drugs. All drugs reported by the elderly patients were classified using the Anatomical Therapeutic and Chemical Classification System. The drug-drug interactions and their severity were assessed using the Micromedex® Healthcare Series. RESULTS: Of the 438 elderly patients in the data base, 376 (85.8%) used pharmacotherapy, 274 were female, and 90.4% of females used drugs. The average number of drugs used by each individual younger than 80 years was 3.2±2.6. Women younger than 80 years old used more drugs than men in the same age group whereas men older than 80 years increased their use of drugs in relation to other age groups. Therefore, 32.6% of men and 49.2% of women described at least one interaction, and 8.1% of men and 10.6% of women described four or more potential drug-drug interactions. Two-thirds of drug-drug interactions were moderate in both genders, and most of them involved angiotensin-converting enzyme inhibitor, non-steroidal anti-inflammatory, loop and thiazide diuretics, and ?-blockers. CONCLUSION: Elderly patients should be closely monitored, based on drug class, gender, age group and nutritional status.

Venturini, Carina Duarte; Engroff, Paula; Ely, Luisa Scheer; de Araujo Zago, Luisa Faria; Schroeter, Guilherme; Gomes, Irenio; De Carli, Geraldo Attilio; Morrone, Fernanda Bueno

2011-01-01

67

The effect of X-rays on the potential difference across frog's skin  

Microsoft Academic Search

K~OPP (19~4) shows that the vitality, injury, recovery and death of a frog's skin can be studied by measuring the potential difference across the skin. The greater its vitality, the greater will be the potential difference; and if the skin is injured, the potential difference will be decreased. The absence of any potential difference across the skin has been taken

Marvin M. D. Williams

1930-01-01

68

Evaluating Potential for Large Releases from CO2 StorageReservoirs: Analogs, Scenarios, and Modeling Needs  

SciTech Connect

While the purpose of geologic storage of CO{sub 2} in deep saline formations is to trap greenhouse gases underground, the potential exists for CO{sub 2} to escape from the target reservoir, migrate upward along permeable pathways, and discharge at the land surface. Such discharge is not necessarily a serious concern, as CO{sub 2} is a naturally abundant and relatively benign gas in low concentrations. However, there is a potential risk to health, safety and environment (HSE) in the event that large localized fluxes of CO{sub 2} were to occur at the land surface, especially where CO{sub 2} could accumulate. In this paper, we develop possible scenarios for large CO{sub 2} fluxes based on the analysis of natural analogues, where large releases of gas have been observed. We are particularly interested in scenarios which could generate sudden, possibly self-enhancing, or even eruptive release events. The probability for such events may be low, but the circumstances under which they might occur and potential consequences need to be evaluated in order to design appropriate site selection and risk management strategies. Numerical modeling of hypothetical test cases is needed to determine critical conditions for such events, to evaluate whether such conditions may be possible at designated storage sites, and, if applicable, to evaluate the potential HSE impacts of such events and design appropriate mitigation strategies.

Birkholzer, Jens; Pruess, Karsten; Lewicki, Jennifer; Tsang,Chin-Fu; Karimjee, Anhar

2005-09-19

69

Altered ion channel conductance and ionic selectivity induced by large imposed membrane potential pulse.  

PubMed Central

The effects of large magnitude transmembrane potential pulses on voltage-gated Na and K channel behavior in frog skeletal muscle membrane were studied using a modified double vaseline-gap voltage clamp. The effects of electroconformational damage to ionic channels were separated from damage to lipid bilayer (electroporation). A 4 ms transmembrane potential pulse of -600 mV resulted in a reduction of both Na and K channel conductivities. The supraphysiologic pulses also reduced ionic selectivity of the K channels against Na+ ions, resulting in a depolarization of the membrane resting potential. However, TTX and TEA binding effects were unaltered. The kinetics of spontaneous reversal of the electroconformational damage of channel proteins was found to be dependent on the magnitude of imposed membrane potential pulse. These results suggest that muscle and nerve dysfunction after electrical shock may be in part caused by electroconformational damage to voltage-gated ion channels.

Chen, W; Lee, R C

1994-01-01

70

Macroscale description of electrokinetic flows at large zeta potentials: Nonlinear surface conduction  

NASA Astrophysics Data System (ADS)

For highly charged dielectric surfaces, the asymptotic structure underlying electrokinetic phenomena in the thin-double-layer limit reshuffles. The large counterion concentration near the surface, associated with the Boltzmann distribution in the diffuse layer, supports appreciable tangential fluxes appearing as effective surface currents in a macroscale description. Their inevitable nonuniformity gives rise in turn to comparable transverse currents, which, for logarithmically large zeta potentials, modify the electrokinetic transport in the electroneutral bulk. To date, this mechanism has been studied only using a weak-field linearization. We present here a generic thin-double-layer analysis of the electrokinetic transport about highly charged dielectric solids, which is not restricted to weak fields. We identify the counterion concentration amplification with the emergence of an internal boundary layer—within the diffuse part of the double layer—characterized by distinct scaling of ionic concentrations and electric field. In this multiscale description, surface conduction is conveniently localized within the internal layer. Our systematic scheme thus avoids the cumbersome procedure of retaining small asymptotic terms which change their magnitude at large zeta potentials. The electrokinetic transport predicted by the resulting macroscale model is inherently accompanied by bulk concentration polarization, which in turn results in nonlinear bulk transport. A novel fundamental subtlety associated with this intrinsic feature, overlooked in the weak-field approximation, has to do with the ambiguity of the “particle zeta potential” concept: In general, even uniformly charged surfaces are characterized by a nonuniform zeta-potential distribution. This impairs the need for a careful identification of the dimensionless number representing the transition to large zeta potentials.

Schnitzer, Ory; Yariv, Ehud

2012-08-01

71

Macroscale description of electrokinetic flows at large zeta potentials: nonlinear surface conduction.  

PubMed

For highly charged dielectric surfaces, the asymptotic structure underlying electrokinetic phenomena in the thin-double-layer limit reshuffles. The large counterion concentration near the surface, associated with the Boltzmann distribution in the diffuse layer, supports appreciable tangential fluxes appearing as effective surface currents in a macroscale description. Their inevitable nonuniformity gives rise in turn to comparable transverse currents, which, for logarithmically large zeta potentials, modify the electrokinetic transport in the electroneutral bulk. To date, this mechanism has been studied only using a weak-field linearization. We present here a generic thin-double-layer analysis of the electrokinetic transport about highly charged dielectric solids, which is not restricted to weak fields. We identify the counterion concentration amplification with the emergence of an internal boundary layer--within the diffuse part of the double layer--characterized by distinct scaling of ionic concentrations and electric field. In this multiscale description, surface conduction is conveniently localized within the internal layer. Our systematic scheme thus avoids the cumbersome procedure of retaining small asymptotic terms which change their magnitude at large zeta potentials. The electrokinetic transport predicted by the resulting macroscale model is inherently accompanied by bulk concentration polarization, which in turn results in nonlinear bulk transport. A novel fundamental subtlety associated with this intrinsic feature, overlooked in the weak-field approximation, has to do with the ambiguity of the "particle zeta potential" concept: In general, even uniformly charged surfaces are characterized by a nonuniform zeta-potential distribution. This impairs the need for a careful identification of the dimensionless number representing the transition to large zeta potentials. PMID:23005765

Schnitzer, Ory; Yariv, Ehud

2012-08-15

72

Measurement of electrostatic potential fluctuation using heavy ion beam probe in large helical device  

SciTech Connect

Heavy ion beam probe (HIBP) for large helical device (LHD) has been improved to measure the potential fluctuation in high-temperature plasmas. The spatial resolution is improved to about 10 mm by controlling the focus of a probe beam. The HIBP is applied to measure the potential fluctuation in plasmas where the rotational transform is controlled by electron cyclotron current drive. The fluctuations whose frequencies change with the time constant of a few hundreds of milliseconds and that with a constant frequency are observed. The characteristics of the latter fluctuation are similar to those of the geodesic acoustic mode oscillation. The spatial profiles of the fluctuations are also obtained.

Ido, Takeshi; Shimizu, Akihiro; Nishiura, Masaki; Nakano, Haruhisa; Ohshima, Shinsuke; Kato, Shinji; Hamada, Yasuji; Yoshimura, Yasuo; Kubo, Shin; Shimozuma, Takashi; Igami, Hiroe; Takahashi, Hiromi; Toi, Kazuo; Watanabe, Fumitake [National Institute for Fusion Science, Gifu 509-5292 (Japan)

2008-10-15

73

Overview of large N QCD with chemical potential at weak and strong coupling  

NASA Astrophysics Data System (ADS)

In this note we summarize the results from a longer article on obtaining the QCD phase diagram as a function of the temperature and chemical potential at large Nc and large Nf in the weak coupling limit ? ? 0, and the strong coupling limit ? ? ?. The weak coupling phase diagram is obtained from the Polyakov line order parameter, and the quark number, calculated using 1-loop perturbation theory for QCD formulated on S1 × S3. The strong coupling phase diagram is obtained from the same observables calculated at leading order in the lattice strong coupling and hopping parameter expansions. We show that the matrix models in these two limits agree at temperatures and chemical potentials which are not too high, such that observables in the strongly-coupled theory can be obtained from the observables in the weakly-coupled theory, and vice versa, using a simple transformation of variables.

Hollowood, Timothy J.; Myers, Joyce C.

2013-04-01

74

Potential impact of wind farms on territories of large eagles in southeastern Spain  

Microsoft Academic Search

Although wind farms in Spain have increased in numbers in recent years, their impact on birds, particularly large raptors,\\u000a has received relatively little attention in the scientific literature. We study the potential impact of 72 wind energy developments\\u000a planned for the south-east of Spain covering 128 golden eagle and 152 Bonelli’s eagle territories using nearest neighbour\\u000a distances (NND) as an

J. E. MartinezJ; J. F. Calvo; J. A. Martínez; I. Zuberogoitia; E. Cerezo; J. Manrique; G. J. Gómez; J. C. Nevado; M. Sánchez; R. Sánchez; J. Bayo; A. Pallarés; C. González; J. M. Gómez; P. Pérez; J. Motos

2010-01-01

75

Ionization potentials of neutral atoms and positive ions in the limit of large atomic number  

Microsoft Academic Search

The many-electron Schrödinger equation allows one to make predictions for the nonrelativistic ionization potentials of both highly charged positive atomic ions and neutral atoms in the limit of large atomic number Z . Beginning with theoretical configuration interaction data on both Li- and Be-like positive atomic ions by K.T. Chung [Phys. Rev. A 45, 7766 (1992); Phys. Rev. A 47,

Nicolás A. Cordero; Norman H. March; Julio A. Alonso

2007-01-01

76

Large-scale purification and long-term stability of human butyrylcholinesterase: a potential bioscavenger drug  

Microsoft Academic Search

Butyrylcholinesterase from human plasma (HuBChE) is a potential drug candidate for detoxification of certain harmful chemicals that contain carboxylic or phosphoric acid ester bonds. Large quantities of purified HuBChE, displaying a high stability upon long-term storage, are required for the evaluation of its therapeutic capacity and its pharmaceutical properties. Several modifications of a previously reported procedure enabled us to purify

Jacob Grunwald; Dino Marcus; Yoel Papier; Lily Raveh; Zipora Pittel; Yacov Ashani

1997-01-01

77

The radiative forcing potential of different climate geoengineering options  

Microsoft Academic Search

Climate geoengineering proposals seek to rectify the Earth's current and potential future radiative imbalance, either by reducing the absorption of incoming solar (shortwave) radiation, or by removing CO2 from the atmosphere and transferring it to long-lived reservoirs, thus increasing outgoing longwave radiation. A fundamental criterion for evaluating geoengineering options is their climate cooling effectiveness, which we quantify here in terms

T. M. Lenton; N. E. Vaughan

2009-01-01

78

The radiative forcing potential of different climate geoengineering options  

Microsoft Academic Search

Climate geoengineering proposals seek to rectify the Earth's current and potential future radiative imbalance, either by reducing the absorption of incoming solar (short- wave) radiation, or by removing CO2 from the atmosphere and transferring it to long-lived reservoirs, thus increasing outgoing longwave radiation. A fundamental criterion for evaluating geoengineering options is their climate cooling effectiveness, which we quantify here in

T. M. Lenton; N. E. Vaughan

2009-01-01

79

Contribution potential of glaciers to water availability in different climate regimes  

PubMed Central

Although reliable figures are often missing, considerable detrimental changes due to shrinking glaciers are universally expected for water availability in river systems under the influence of ongoing global climate change. We estimate the contribution potential of seasonally delayed glacier melt water to total water availability in large river systems. We find that the seasonally delayed glacier contribution is largest where rivers enter seasonally arid regions and negligible in the lowlands of river basins governed by monsoon climates. By comparing monthly glacier melt contributions with population densities in different altitude bands within each river basin, we demonstrate that strong human dependence on glacier melt is not collocated with highest population densities in most basins.

Kaser, Georg; Grosshauser, Martin; Marzeion, Ben

2010-01-01

80

SURVIVAL AND REPRODUCTIVE POTENTIAL OF DIFFERENT COHORTS OF Calomys venustus  

Microsoft Academic Search

In order to determine winter survival and reproductive potential in cohort 2 (C2) and cohort 3 (C3) of Calomys venustus we compared these parameters between individuals of these cohorts and their offspring. Forty six males (13 C2 and 33 C3) and 29 females (21 C2 and 8 C3) were observed from June to September to determine winter survival. There were

María D. Gomez; María C. Provensal; Jaime J. Polop

2007-01-01

81

Age differences in visual evoked potential estimates on interhemishperic transfer  

Microsoft Academic Search

Twenty-six younger (ages 18-36 years) and 19 older (ages 60-88 years) healthy right-handed men and women were tested for interhemispheric transfer by using visual evoked potentials to laterally presented checkerboards. Interhemispheric transfer time (IHTT) was estimated by subtracting latencies for both P100 and N160 peaks of the waveform contralateral to the stimulus from the waveform ipsilateral to the stimulus for

Matthew J. Hoptman; Richard J. Davidson; Adalsteinn Gudmundsson; Ronald T. Schreiber; William B. Ershler

1996-01-01

82

Differences in Characteristics of the ERP System Selection Process Between Small or Medium and Large Organizatons  

Microsoft Academic Search

In this paper we detail the results from an empirical study concerning differences in characteristics of the ERP system selection process between small or medium and large sized organizations. In particular we address the fields of software packages considered and chosen, the weights assigned to different selection criteria, the persons involved in this process, the methods employed and implementation characteristics

Edward Bernroider; Stefan Koch

2000-01-01

83

Compact Finite Difference Time Domain Absorbing Boundary Conditions for Electrically Large Waveguide Modeling  

Microsoft Academic Search

This work extends a previous effort in optimizing the compact finite difference time domain algorithm for modeling electrically large waveguides by investigating the effect of their electrical size on perfectly matched layer absorbing boundary conditions. Sensitivity analysis is conducted via an optimization procedure where actual finite difference time domain simulations serve as input, and optimum perfectly matched layer parameters serve

Mohammed F. Hadi

2009-01-01

84

Whitefly control potential of Eretmocerus parasitoids with different reproductive modes  

Microsoft Academic Search

Whiteflies (Homoptera; Aleyrodidae) are amongst the key pests of vegetable, ornamental, and agronomic crops throughout the world. Because of failing and expensive chemical control, much research has been directed at developing biological control by searching for efficient natural enemies of whiteflies. Among different categories of natural enemies, parasitoids have been efficient control agents and cost effective. The aim of the

M. J. Ardeh

2005-01-01

85

ABC and Variability Accounting Differences and potential benefits of integration  

Microsoft Academic Search

Activity-Based Costing (ABC) started out as a vehicle for (i) improved product costing for use in pricing, switched later to (ii) profit priorities using hierarchies of cost assignment, and now focuses on (iii) accounting for capacity constraints situations.Firstly, the paper demonstrates that the data requirements for these three different uses of ABC can be met by recording the following characteristics

Poul Israelsen

1994-01-01

86

Sugar potential of different Jerusalem artichoke cultivars according to harvest  

Microsoft Academic Search

Crop growth and development and yield of Jerusalem artichoke were studied in field crops harvested periodically during 2 years. Investigations were carried out on two topics: (i) cultivation of different Jerusalem artichoke cultivars, (ii) optimization of analytical procedures for sugars determination in order to select cultivar and harvest period for optimization of sugar production. Agronomic investigations have shown this crop

S. Schorr-Galindo; J. P. Guiraud

1997-01-01

87

Utilization of different types of dietary fibres by potential probiotics.  

PubMed

A better understanding of the functionality of probiotics and dietary fibres with prebiotic activity is required for the development of improved synbiotic preparations. In this study, utilization of ?(2-1) fructans, galactooligosaccharides, and plant polysaccharides as prebiotics by lactobacilli, bifidobacteria, and pediococci was investigated. Our results demonstrate that prebiotics with linear chains consisting of galactose units are better utilized by probiotics than are those consisting of glucose and fructose units, and the ability of probiotic bacteria to utilize prebiotics is strain-specific. In addition, rye fructooligosaccharides represent a prebiotic fibre that supports the growth of a wide range of probiotic cultures and as such has a potential to improve the successfulness of probiotic treatments. This study also demonstrates dietary fibre utilization by pediococci and provides data supporting the possible use of pediococci as a probiotic in synbiotic combinations. PMID:21958046

Mei, Gui-Ying; Carey, Christine M; Tosh, Susan; Kostrzynska, Magdalena

2011-10-01

88

Large anti-HER2/neu liposomes for potential targeted intraperitoneal therapy of micrometastatic cancer  

PubMed Central

Effective targeting and killing of intraperitoneally disseminated micrometastases remains a challenge. Objective/Methods In this work, we evaluated the potential of antibody-labeled PEGylated large liposomes as vehicles for direct intraperitoneal (i.p.) drug delivery with the aim to enhance the tumor-to-normal organ ratio and to improve the bioexposure of cancer cells to the delivered therapeutics while shifting the toxicities toward the spleen. These targeted liposomes are designed to combine: (1) specific targeting to and internalization by cancer cells mediated by liposome-conjugated tumor-specific antibodies, (2) slow clearance from the peritoneal cavity, and (3) shift of normal organ toxicities from the liver to the spleen due to their relatively large size. Results Conjugation of anti-HER2/neu antibodies to the surface of large (approximately 600 nm in diameter) PEGylated liposomes results in fast, specific binding of targeted liposomes to cancer cells in vitro, followed by considerable cellular internalization. In vivo, after i.p. administration, these liposomes exhibit fast, specific binding to i.p. cancerous tumors. Large liposomes are slowly cleared from the peritoneal cavity, and they exhibit increased uptake by the spleen relative to the liver, while targeted large liposomes demonstrate specific tumor uptake at early times. Although tissue and tumor uptake are greater for cationic liposomes, the tumor-to-liver and spleen-to-liver ratios are similar for both membrane compositions, suggesting a primary role for the liposome’s size, compared to the liposome’s surface charge. Conclusions The findings of this study suggest that large targeted liposomes administered i.p. could be a potent drug-delivery strategy for locoregional therapy of i.p. micrometastatic tumors.

Sofou, Stavroula; Enmon, Richard; Palm, Stig; Kappel, Barry; Zanzonico, Pat; McDevitt, Michael R.; Scheinberg, David A.; Sgouros, George

2011-01-01

89

Vermicomposting potential of Perionyx sansibaricus (Perrier) in different waste materials  

Microsoft Academic Search

The decomposition efficiency of Perionyx sansibaricus (Perrier) for vermicomposting was evaluated by using a variety of wastes such as agriculture waste, farm yard manure and urban solid waste. Vermicomposting resulted in significant increase in total N (80.8–142.3%), phosphorous (33.1–114.6%) and potassium (26.3–125.2%), whereas decrease in organic C (14.0–37.0%) as well as C:N ratio (52.4–69.8%) in different experimental beddings. P. sansibaricus

Surendra Suthar

2007-01-01

90

Potential pathogens and effective disinfectants on public telephones at a large urban United States university.  

PubMed

Telephones can carry potential bacterial pathogens, posing a risk for transfer of pathogens to users' hands. This study examined 25 mouthpieces of public telephones at a large urban U.S. university located in an area of rising incidence of community-acquired staphylococcal infections. Coagaulase-negative staphylococci were most commonly isolated (64% of mouthpieces). Potential pathogens isolated included Staphylococcus aureus, vancomycin-susceptible Enterococcus, and Klebsiella ozaenae. The efficacy of disinfectants on reducing bacterial counts on telephone mouthpieces was also investigated. Staphyloccocus aurens, Pseudomonas aeruginosa, and Enterococcusfaecalis were inoculated onto mouthpieces and challenged with disinfectant wipes. Bacterial counts were reduced substantially for all three organisms by wipes containing either 70% isopropyl alcohol, 1.84% sodium hypochlorite, or quaternary ammonium compounds. The sodium hypochlorite-based cleaner demonstrated 100% efficacy at removing or killing test organisms from telephone mouthpieces. These data suggest that tested cleaners may be appropriate and needed for public telephone disinfection. PMID:19192741

Annand, John W; Bajaj, Nikesh; Sheth, Anand; Burgess, Jaqqwon; Brooke, Joanna S

91

Quantitative potential measurements of nanoparticles with different surface charges in liquid by open-loop electric potential microscopy  

NASA Astrophysics Data System (ADS)

Local potential distribution plays important roles in physical, chemical and biological processes at a solid/liquid interface. However, the measurement of a local potential distribution in liquid has been a long-standing challenge, which has hindered understanding of the mechanisms for the various interfacial phenomena. Recently, we have developed a method to overcome this problem [Kobayashi et al., Rev. Sci. Instrum. 81, 123705 (2010)], which is referred to as open-loop electric potential microscopy (OL-EPM). Here, we present its first application to quantitative measurements of local potential distribution in liquid. In OL-EPM, an ac bias voltage is applied between a tip and sample and the first and second harmonic cantilever oscillations induced by the electrostatic force are detected and used for the calculation of a potential value. In the equation for the potential calculation, here we introduce a correction factor to cancel out the error caused by the difference in the deflection sensitivity to the first and second harmonic electrostatic forces. With the improved method, we have performed potential measurements of two types of latex beads with different surface charges. The measured potential difference between the different types of latex beads approximately corresponds to their zeta potential difference, which demonstrates the quantitative capability of OL-EPM.

Kobayashi, Naritaka; Asakawa, Hitoshi; Fukuma, Takeshi

2011-08-01

92

Decay process of a large surface potential of Alq{sub 3} films by heating  

SciTech Connect

In order to clarify the decaying process of a large surface potential of as-deposited Alq{sub 3} films on a metal electrode by heating and photoexposure, Kelvin probe method and optical second harmonic generation (SHG) measurement were employed. The change of surface potential during heating was not in accordance with the change of SH intensity at a temperature lower than 100 deg. C. For heating at less than 100 deg. C and photoexposure, x-ray diffractions showed no change. We discussed these results from a viewpoint of the disordering of orientational polar structure of Alq{sub 3} molecules and the injection of electrons from metal electrodes. Then the following model was suggested. The potential decay process of Alq{sub 3} films on aluminum (Al) electrodes by heating was found to be due to electron injection from Al electrode into Alq{sub 3} films, which does not accompany the structural change of Alq{sub 3} films in the region of temperature lower than 100 deg. C, though the crystallization of Alq{sub 3} evaporated film was suggested at a temperature higher than 100 deg. C. On the other hand, the disordering of polar structure of Alq{sub 3} film that does not accompany the structural change was elucidated as the potential decay process by photoexposure.

Kajimoto, Norifumi; Manaka, Takaaki; Iwamoto, Mitsumasa [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

2006-09-01

93

Individual differences in fear potentiated startle in behaviorally inhibited children.  

PubMed

Behavioral inhibition (BI) is a temperament characterized during early childhood by increased fearfulness to novelty, social reticence to unfamiliar peers, and heightened risk for the development of anxiety. Heightened startle responses to safety cues have been found among behaviorally inhibited adolescents who have an anxiety disorder suggesting that this measure may serve as a biomarker for the development of anxiety amongst this risk population. However, it is unknown if these aberrant startle patterns emerge prior to the manifestation of anxiety in this temperament group. The current study examined potentiated startle in 7-year-old children characterized with BI early in life. High behaviorally inhibited children displayed increased startle magnitude to safety cues, particularly during the first half of the task, and faster startle responses compared to low behaviorally inhibited children. These findings suggest that aberrant startle responses are apparent in behaviorally inhibited children during early childhood prior to the onset of a disorder and may serve as a possible endophenotype for the development of anxiety. © 2013 Wiley Periodicals, Inc. Dev Psychobiol. PMID:23341151

Barker, Tyson V; Reeb-Sutherland, Bethany C; Fox, Nathan A

2013-01-22

94

Characterization of Different Functionalized Lipidic Nanocapsules as Potential Drug Carriers  

PubMed Central

Lipid nanocapsules (LNC) based on a core-shell structure consisting of an oil-filled core with a surrounding polymer layer are known to be promising vehicles for the delivery of hydrophobic drugs in the new therapeutic strategies in anti-cancer treatments. The present work has been designed as basic research about different LNC systems. We have synthesized—and physico-chemically characterized—three different LNC systems in which the core was constituted by olive oil and the shell by different phospholipids (phosphatidyl-serine or lecithin) and other biocompatible molecules such as Pluronic® F68 or chitosan. It is notable that the olive-oil-phosphatidyl-serine LCN is a novel formulation presented in this work and was designed to generate an enriched carboxylic surface. This carboxylic layer is meant to link specific antibodies, which could facilitate the specific nanocapsule uptake by cancer cells. This is why nanoparticles with phosphatidyl-serine in their shell have also been used in this work to form immuno-nanocapsules containing a polyclonal IgG against a model antigen (C-reactive protein) covalently bounded by means of a simple and reproducible carbodiimide method. An immunological study was made to verify that these IgG-LNC complexes showed the expected specific immune response. Finally, a preliminary in vitro study was performed by culturing a breast-carcinoma cell line (MCF-7) with Nile-Red-loaded LNC. We found that these cancer cells take up the fluorescent Nile- Red molecule in a process dependent on the surface properties of the nanocarriers.

Sanchez-Moreno, Paola; Ortega-Vinuesa, Juan Luis; Martin-Rodriguez, Antonio; Boulaiz, Houria; Marchal-Corrales, Juan Antonio; Peula-Garcia, Jose Manuel

2012-01-01

95

Improving High School Students' Understanding of Potential Difference in Simple Electric Circuits  

ERIC Educational Resources Information Center

|This paper reports two studies into the understanding of the concept of potential difference in the current-potential difference-resistance context among 8th-12th graders (Study 1), and the efficiency of a learning device derived from Social Judgment Theory (Study 2). These two studies showed that: (a) when asked to infer potential difference

Liegeois, Laurent; Chasseigne, G'erard; Papin, Sophie; Mullet, Etienne

2003-01-01

96

Vascular large conductance calcium-activated potassium channels: Functional role and therapeutic potential  

Microsoft Academic Search

Large-conductance Ca2+-activated K+ channels (BKCa or maxiK channels) are expressed in different cell types. They play an essential role in the regulation of various cell functions.\\u000a In particular, BKCa channels have been extensively studied in vascular smooth muscle cells, where they contribute to the control of vascular\\u000a tone. They facilitate the feedback regulation against the rise of intracellular Ca2+, membrane

Birgit Eichhorn; Dobromir Dobrev

2007-01-01

97

Five potential principles for understanding cultural differences in relation to individual differences  

Microsoft Academic Search

This paper deals with psychological differences between two cultures, with respect to the differences between individuals in those same cultures. Five principles are presented which describe either actual or probable empirical relationships between within- and between-culture differences, and a possible theoretical account is given for each of the presumed differences. (1) The differences between “cultures” seem “bigger” than the actual

Paul Rozin

2003-01-01

98

Systematic study of the fusion barriers using different proximity-type potentials for N=Z colliding nuclei: New extensions  

SciTech Connect

By using 14 different versions and parametrizations of a proximity potential and two new versions of the potential proposed in this paper, we perform a comparative study of fusion barriers by studying 26 symmetric reactions. The mass asymmetry eta{sub A}=((A{sub 2}-A{sub 1}/A{sub 2}+A{sub 1})), however, is very large. Our detailed investigation reveals that most of the proximity potentials reproduce experimental data within +-8% on average. A comparison of fusion cross sections indicates that Bass 80, AW 95, and Denisov DP potentials have a better edge than other potentials. We also propose new versions of the proximity potential as well as Denisov parametrized potential. These new versions improve agreement with the data.

Dutt, Ishwar; Puri, Rajeev K. [Department of Physics, Panjab University, Chandigarh 160 014 (India)

2010-04-15

99

Systematic study of the fusion barriers using different proximity-type potentials for N=Z colliding nuclei: New extensions  

NASA Astrophysics Data System (ADS)

By using 14 different versions and parametrizations of a proximity potential and two new versions of the potential proposed in this paper, we perform a comparative study of fusion barriers by studying 26 symmetric reactions. The mass asymmetry ?A=((A2-A1)/(A2+A1)), however, is very large. Our detailed investigation reveals that most of the proximity potentials reproduce experimental data within ±8% on average. A comparison of fusion cross sections indicates that Bass 80, AW 95, and Denisov DP potentials have a better edge than other potentials. We also propose new versions of the proximity potential as well as Denisov parametrized potential. These new versions improve agreement with the data.

Dutt, Ishwar; Puri, Rajeev K.

2010-04-01

100

Infants use different mechanisms to make small and large number ordinal judgments.  

PubMed

Previous research has shown indirectly that infants may use two different mechanisms--an object tracking system and an analog magnitude mechanism--to represent small (<4) and large (?4) numbers of objects, respectively. The current study directly tested this hypothesis in an ordinal choice task by presenting 10- to 12-month-olds with a choice between different numbers of hidden food items. Infants reliably chose the larger amount when choosing between two exclusively small (1 vs. 2) or large (4 vs. 8) sets, but they performed at chance when one set was small and the other was large (2 vs. 4) even when the ratio between the sets was very favorable (2 vs. 8). The current findings support the two-mechanism hypothesis and, furthermore, suggest that the representations from the object tracking system and the analog magnitude mechanism are incommensurable. PMID:22608189

vanMarle, Kristy

2012-05-17

101

Differences in seed rain composition in small and large fragments in the northeast Brazilian Atlantic Forest.  

PubMed

Tropical forests are seriously threatened by fragmentation and habitat loss. The impact of fragment size and forest configuration on the composition of seed rain is insufficiently studied. For the present study, seed rain composition of small and large forest fragments (8-388?ha) was assessed in order to identify variations in seed abundance, species richness, seed size and dispersal mode. Seed rain was documented during a 1-year period in three large and four small Atlantic Forest fragments that are isolated by a sugarcane matrix. Total seed rain included 20,518 seeds of 149 species of trees, shrubs, palms, lianas and herbs. Most species and seeds were animal-dispersed. A significant difference in the proportion of seeds and species within different categories of seed size was found between small and large fragments. Small fragments received significantly more very small-sized seeds (<0.3?cm) and less large-seeded species (>1.5?cm) that were generally very rare, with only one species in small and eight in large fragments. We found a negative correlation between the inflow of small-sized seeds and the percentage of forest cover. Species richness was lower in small than in large fragments, but the difference was not very pronounced. Given our results, we propose changing plant species pools through logging, tree mortality and a high inflow of pioneer species and lianas, especially in small forest fragments and areas with low forest cover. Connecting forest fragments through corridors and reforestation with local large-seeded tree species may facilitate the maintenance of species diversity. PMID:22372687

Knörr, U C; Gottsberger, G

2012-02-28

102

Theoretical and experimental investigation of heat conduction for large temperature differences at arbitrary Knudsen number  

Microsoft Academic Search

The plane steady-state heat conduction in monatomic gases at large temperature differences was studied. An approximate solution of the Boltzman equation, based on a two-sided Maxwellian velocity distribution function and the model of Maxwellian molecules, was investigated. This solution, obtained by using Maxwell's moment method, can be used to determine macroscopic quantities of state for arbitrary Knudsen numbers. A plane

D. Braun

1976-01-01

103

Finite Difference Thermoelastic Analysis of Suspended Cables Including Extensibility and Large Sag Effects  

Microsoft Academic Search

This paper presents and validates an original and practical finite difference model to investigate the thermoelastic response of suspended cables. The mathematical formulations are provided for various loading cases. The model includes the effects of cable extensibility and large sag, as well as variability of temperature gradients and thermal properties of the cable along its arc-length. The formulations are programmed

Najib Bouaanani; Paul Marcuzzi

2011-01-01

104

Student Engagement at a Large Suburban Community College: Gender and Race Differences  

ERIC Educational Resources Information Center

Previous research shows that there are individual differences in academic achievement associated with gender and race. Research also suggests that student engagement is an important determinant of student outcomes/achievement. The present study explored student engagement at an extra-large community college. It specifically investigated possible…

Sontam, Varalakshmi; Gabriel, George

2012-01-01

105

Large magnetocrystalline anisotropy in bilayer transition metal phases from first-principles full-potential calculations  

NASA Astrophysics Data System (ADS)

The computational framework of this study is based on the local-spin-density approximation with first-principles full-potential linear muffin-tin orbital calculations including orbital polarization (OP) correction. We have studied the magnetic anisotropy for a series of bilayer CuAu(I)-type materials such as FeX, MnX (X=Ni,Pd,Pt), CoPt, NiPt, MnHg, and MnRh in a ferromagnetic state using experimental structural parameters to understand the microscopic origin of magnetic-anisotropy energy (MAE) in magnetic multilayers. Except for MnRh and MnHg, all these phases show perpendicular magnetization. We have analyzed our results in terms of angular momentum-, spin- and site-projected density of states, magnetic-angular-momentum-projected density of states, orbital-moment density of states, and total density of states. The orbital-moment number of states and the orbital-moment anisotropy for FeX (X=Ni,Pd,Pt) are calculated as a function of band filling to study its effect on MAE. The total and site-projected spin and orbital moments for all these systems are calculated with and without OP when the magnetization is along or perpendicular to the plane. The results are compared with available experimental as well as theoretical results. Our calculations show that OP always enhances the orbital moment in these phases and brings them closer to experimental values. The changes in MAE are analyzed in terms of exchange splitting, spin-orbit splitting, and tetragonal distortion/crystal-field splitting. The calculated MAE is found to be in good agreement with experimental values when the OP correction is included. Some of the materials considered here show large magnetic anisotropy of the order of meV. In particular we found that MnPt will have a very large MAE if it could be stabilized in a ferromagnetic configuration. Our analysis indicates that apart from large spin-orbit interaction and exchange interaction from at least one of the constituents, a large crystal-field splitting originating from the tetragonal distortion is also a necessary condition for having large magnetic anisotropy in these materials. Our calculation predicts large orbital moment in the hard axis in the case of FePt, MnRh, and MnHg against expectation.

Ravindran, P.; Kjekshus, A.; Fjellvåg, H.; James, P.; Nordström, L.; Johansson, B.; Eriksson, O.

2001-04-01

106

Potential of large diameter MgF2 single crystal grown by Czochralski method  

NASA Astrophysics Data System (ADS)

Magnesium fluoride (MgF2) single crystal is expected as the alternative of Quartz for polarizing materials in high power lithography system. MgF2 is anisotropic crystal and its physical properties are different along each crystal axes. Therefore it is difficult to make large diameter single crystal by using Bridgman method which is mainly used for growth of fluoride crystals. We have been studying on making large diameter and high quality single crystal by using Czochralski (CZ) method [1,2]. Previously we reported the stable growth of it with 150mm diameter. This time we succeeded to grow the crystal with over 200mm diameter. Additionally, by improving the purification process and growth process, we succeeded to reduce 75 percent of the amount of color center induced by irradiation of ArF laser.

Hashimoto, Yasuhiro; Ikeda, Yuichi; Ariyuki, Masao; Mochizuki, Naoto; Nawata, Teruhiko

2011-10-01

107

Beyond-mean-field behavior of large Bose-Einstein condensates in double-well potentials  

NASA Astrophysics Data System (ADS)

For the dynamics of Bose-Einstein condensates (BECs), differences between mean-field (Gross-Pitaevskii) physics and N-particle quantum physics often disappear if the BEC becomes larger and larger. In particular, the time scale for which both dynamics agree should thus become larger if the particle number increases. For BECs in a double-well potential, we find both examples for which this is the case and examples for which differences remain even for huge BECs on experimentally realistic short time scales. By using a combination of numerical and analytical methods, we show that the differences remain visible on the level of expectation values even beyond the largest possible numbers realized experimentally for BECs with ultracold atoms.

Gertjerenken, Bettina; Weiss, Christoph

2013-09-01

108

Solid lipid nanoparticles: continuous and potential large-scale nanoprecipitation production in static mixers.  

PubMed

This work aimed at developing continuous and scalable nanoprecipitation synthesis of solid lipid nanoparticles (SLN) by mixing lipids acetonic solution with water using static mixers. The developed platform exhibited good control over the nanoprecipitation process and enabled the production of SLN below 200 nm at a throughput of 37.5-150 g/h (for 25 mg/ml lipid solution at a flow rate of 25-100 ml/min). Among the several process parameters investigated, the lipid concentration played primary role in influencing the size of the SLN and higher lipid concentration resulted in relatively larger particles. Fenofibrate, a model drug, has been successfully loaded into the SLN. Our work demonstrates the potential of applying static mixing-nanoprecipitation for continuous and large scale production of SLN. PMID:22326649

Dong, Yuancai; Ng, Wai Kiong; Shen, Shoucang; Kim, Sanggu; Tan, Reginald B H

2012-01-25

109

Nonhost Resistance of Barley to Different Fungal Pathogens Is Associated with Largely Distinct, Quantitative Transcriptional Responses1[W][OA  

PubMed Central

Nonhost resistance protects plants against attack by the vast majority of potential pathogens, including phytopathogenic fungi. Despite its high biological importance, the molecular architecture of nonhost resistance has remained largely unexplored. Here, we describe the transcriptional responses of one particular genotype of barley (Hordeum vulgare subsp. vulgare ‘Ingrid’) to three different pairs of adapted (host) and nonadapted (nonhost) isolates of fungal pathogens, which belong to the genera Blumeria (powdery mildew), Puccinia (rust), and Magnaporthe (blast). Nonhost resistance against each of these pathogens was associated with changes in transcript abundance of distinct sets of nonhost-specific genes, although general (not nonhost-associated) transcriptional responses to the different pathogens overlapped considerably. The powdery mildew- and blast-induced differences in transcript abundance between host and nonhost interactions were significantly correlated with differences between a near-isogenic pair of barley lines that carry either the Mlo wild-type allele or the mutated mlo5 allele, which mediates basal resistance to powdery mildew. Moreover, during the interactions of barley with the different host or nonhost pathogens, similar patterns of overrepresented and underrepresented functional categories of genes were found. The results suggest that nonhost resistance and basal host defense of barley are functionally related and that nonhost resistance to different fungal pathogens is associated with more robust regulation of complex but largely nonoverlapping sets of pathogen-responsive genes involved in similar metabolic or signaling pathways.

Zellerhoff, Nina; Himmelbach, Axel; Dong, Wubei; Bieri, Stephane; Schaffrath, Ulrich; Schweizer, Patrick

2010-01-01

110

Fatty acid profiles of muscle from large yellow croaker (Pseudosciaena crocea R.) of different age  

PubMed Central

We investigated the fatty acid profiles of muscle from large yellow croaker (Pseudosciaena crocea R.) of different age. One- and two-year-old fish were cultured in floating net cages and sampled randomly for analysis. Moisture, protein, lipid and ash contents were determined by methods of Association of Analytical Chemist (AOAC) International. Fatty acid profile was determined by gas chromatography. Crude protein, fat, moisture and ash contents showed no significant differences between the two age groups. The contents of total polyunsaturated fatty acids and docosahexaenoic acid (DHA) were significantly higher and eicosapentaenoic acid (EPA) content was significantly lower in the two-year-old large yellow croaker than in the one-year-old (P<0.05). No significant differences were observed in the contents of total saturated fatty acids and monounsaturated fatty acids, or the ratio of n-3/n-6 fatty acids among the large yellow croakers of the two age groups. We conclude that large yellow croakers are good food sources of EPA and DHA.

Tang, Hong-gang; Chen, Li-hong; Xiao, Chao-geng; Wu, Tian-xing

2009-01-01

111

Reactant concentration difference induced microstructure transformation of large-area vapor-grown carbon nanofibers  

NASA Astrophysics Data System (ADS)

We explore the effect of mass transport on the microstructure formation of chemical-vapor-deposited carbon nanofibers (CNFs), considering the decrease in carbon source gas concentration along the large-area substrate surface. The microstructures of the CNFs grown along the substrate are transformed from porous, to platelet, to herringbone, and exhibit increased graphite ordering. A model for CNF growth under different reactant concentrations is suggested. The results indicate the critical role of mass transport on the CNF growth mechanism and suggest that adjusting the reactant concentration is an easy way of controlling the CNF microstructures during large-area synthesis.

Tang, Xian; Xie, Zhiyong; Yang, Piaopiao; Liu, Chunxuan; Huang, Dong; Huang, Qizhong

2013-10-01

112

Toward large N thermal QCD from dual gravity: The heavy quarkonium potential  

SciTech Connect

We continue our study on the gravity duals for strongly coupled large N QCD with fundamental flavors both at zero and nonzero temperatures. The gravity dual at zero temperature captures the logarithmic runnings of the coupling constants at far IR and the almost conformal, albeit strongly coupled, behavior at the UV. The full UV completion of gauge theory is accomplished in the gravity side by attaching an anti-de Sitter cap to the IR geometry described in our previous work. Attaching such an anti-de Sitter cap is highly nontrivial because it amounts to finding the right interpolating geometry and sources that take us from a gravity solution with nonzero three-form fluxes to another one that has almost vanishing three-form fluxes. In this paper we give a concrete realization of such a scenario, completing the program advocated in our earlier paper. One of the main advantages of having such a background, in addition to providing a dual description of the required gauge theory, is the absence of Landau poles and consequently the UV divergences of the Wilson loops. The potential for the heaviest fundamental quark-antiquark pairs, which are like the heavy quarkonium states in realistic QCD, can be computed and their linear behavior at large separations and zero temperature could be demonstrated. At small separations the expected Coulombic behavior appears to dominate. On the other hand, at nonzero temperatures interesting properties like heavy quarkonium-type suppressions and melting are shown to emerge from our gravity dual. We provide some discussions of the melting temperature and compare our results with the charmonium spectrum and lattice simulations. We argue that, in spite of the large N nature of our construction, certain model-independent predictions can be made.

Mia, Mohammed; Dasgupta, Keshav; Gale, Charles; Jeon, Sangyong [Ernest Rutherford Physics Building, McGill University, 3600 University Street, Montreal Quebec, H3A 2T8 (Canada)

2010-07-15

113

Potential consequences of climate change for primary production and fish production in large marine ecosystems  

PubMed Central

Existing methods to predict the effects of climate change on the biomass and production of marine communities are predicated on modelling the interactions and dynamics of individual species, a very challenging approach when interactions and distributions are changing and little is known about the ecological mechanisms driving the responses of many species. An informative parallel approach is to develop size-based methods. These capture the properties of food webs that describe energy flux and production at a particular size, independent of species' ecology. We couple a physical–biogeochemical model with a dynamic, size-based food web model to predict the future effects of climate change on fish biomass and production in 11 large regional shelf seas, with and without fishing effects. Changes in potential fish production are shown to most strongly mirror changes in phytoplankton production. We project declines of 30–60% in potential fish production across some important areas of tropical shelf and upwelling seas, most notably in the eastern Indo-Pacific, the northern Humboldt and the North Canary Current. Conversely, in some areas of the high latitude shelf seas, the production of pelagic predators was projected to increase by 28–89%.

Blanchard, Julia L.; Jennings, Simon; Holmes, Robert; Harle, James; Merino, Gorka; Allen, J. Icarus; Holt, Jason; Dulvy, Nicholas K.; Barange, Manuel

2012-01-01

114

Fatty acid profiles of muscle from large yellow croaker ( Pseudosciaena crocea R.) of different age  

Microsoft Academic Search

We investigated the fatty acid profiles of muscle from large yellow croaker (Pseudosciaena crocea R.) of different age. One- and two-year-old fish were cultured in floating net cages and sampled randomly for analysis. Moisture,\\u000a protein, lipid and ash contents were determined by methods of Association of Analytical Chemist (AOAC) International. Fatty\\u000a acid profile was determined by gas chromatography. Crude protein,

Hong-gang Tang; Li-hong Chen; Chao-geng Xiao; Tian-xing Wu

2009-01-01

115

pi^+ - pi^0 mass difference and S parameter in the large N_f QCD  

Microsoft Academic Search

In the framework of the Schwinger-Dyson equation and the Bethe-Salpeter\\u000aequation in the improved ladder approximation, we calculate the S parameter and\\u000aan analogue of the \\\\pi^+ - \\\\pi^0 mass difference \\\\Delta m_\\\\pi^2 \\\\equiv\\u000am_{\\\\pi^+}^2 -m_{\\\\pi^0}^2 as well as the NG boson decay constant f_\\\\pi on the\\u000asame footing in the large N_f QCD, through the difference between the vector

Masayasu Harada; Masafumi Kurachi; Koichi Yamawaki

2005-01-01

116

Influences of Source Heterogeneity and Potential Temperature on the Generation of Basalts from the North Atlantic Large Igneous Province  

NASA Astrophysics Data System (ADS)

Source heterogeneity and mantle potential temperature are important factors affecting the mantle melting process and must be adequately accounted for to interpret the compositions of mantle-derived melts derived from a variety of tectonomagmatic settings. Several previous studies have attempted to simplify the problem by modeling the melting of a homogeneous source, or by creating 1-D melting models of a heterogeneous source (i.e. solid-solid source mixing). The results of these studies are limited as the latter approach places no constraints on pressures and extents of melting while the former approach does not account for the role of non- peridotite lithologies in the source. We have begun investigating 2-D models using a modified version of the REEBOX polybaric melting model of [1] in an attempt to gain insight into melt compositions related to the effects of the melting process (related to potential temperature) while simultaneously identifying the chemical effects of source heterogeneity. This new model incorporates experimentally - determined melt productivity functions, melting reactions and solidus pressures for eclogite and peridotite source lithologies. At a given potential temperature, model outputs produce grids in trace element and isotope space that reflect variable mixing of melts derived from eclogite and peridotite source lithologies at different segregation pressures from the melting column. Consequently, we are able to qualitatively assess relative pressures and extents of melting within the melting column for comparison with basalt compositions. To better understand the influences of source heterogeneity and potential temperature within the North Atlantic Large Igneous Province, we apply this model to volcanic products from the Paleocene rifted margin of Greenland and the modern ridge system. In the case of the east Greenland flood basalts, variations in contributions from a source involving highly depleted peridotite and eclogite and changes in potential temperatures can be distinguished. These insights are useful in constraining the nature of the chemical and thermal anomaly associated with the ancestral Iceland plume. (1) Fram and Lesher, 1993, Nature, v 363, p 712-714

Brown, E. L.; Lesher, C. E.

2007-12-01

117

Potential biases in the detection of planetary systems with large transit timing variations  

NASA Astrophysics Data System (ADS)

The transit timing variations (TTVs) technique provides a powerful tool to detect additional planets in transiting exoplanetary systems. In this Letter, we show how transiting planets with significant TTVs can be systematically missed, or catalogued as false positives, by current transit search algorithms, unless they are in multitransit systems. If the period of the TTVs, PTTV, is longer than the time baseline of the observations and its amplitude, ATTV, is larger than the timing precision limit of the data, transiting planet candidates are still detected, but with incorrect ephemerides. Therefore, they will be discarded during follow-up. When PTTV is shorter than the time baseline of the observations and ATTV is sufficiently large, constant period search algorithms find an average period for the system, which results in altered transit durations and depths in the folded light curves. Those candidates can get subsequently discarded as eclipsing binaries, grazing eclipses or blends. Also, for large enough ATTV values, the transits can get fully occulted by the photometric dispersion of the light curves. These detection biases could explain the observed statistical differences between the frequency of multiple systems among planets detected via other techniques and those detected via transits. We suggest that new transit search algorithms allowing for non-constant period planets should be implemented.

García-Melendo, E.; López-Morales, M.

2011-10-01

118

Large Extracellular Loop of Tetraspanin as a Potential Vaccine Candidate for Filariasis  

PubMed Central

Lymphatic filariasis affects nearly 120 million people worldwide and mass preventive chemotherapy is currently used as a strategy to control this infection. This has substantially reduced the incidence of the infection in several parts of the world. However, a prophylactic vaccine would be more effective in preventing future infections and will supplement the mass chemotherapy efforts. Unfortunately, there is no licensed vaccine available currently to prevent this infection. Molecules expressed on the surface of the parasite are potential candidates for vaccine development as they are exposed to the host immune system. In this study we show that the large extracellular loop of tetraspanin (TSP LEL), a protein expressed on the cuticle of Brugia malayi and Wuchereria bancrofti is a potential vaccine candidate. Our results showed that BmTSP LEL is expressed on the surface of B. malayi infective third stage larvae (L3) and sera from human subjects who are putatively immune to lymphatic filariasis carry high titer of IgG1 and IgG3 antibodies against BmTSP LEL and WbTSP LEL. We also showed that these antibodies in the sera of human subjects can participate in the killing of B. malayi L3 in an antibody dependent cell-mediated cytotoxicity mechanism. Vaccination trials in mice showed that close to 64% protection were achieved against challenge infections with B. malayi L3. Immunized animals showed high titer of anti-WbTSP LEL IgG1, IgG2a and IgG2b antibodies in the sera and IFN-? secreting cells in the spleen. Onchocerca volvulus another filarial parasite also expresses TSP LEL. Cross-reactivity studies showed that IgG1 antibody in the sera of endemic normal subjects, recognize OvTSP LEL. Similarly, anti-OvTSP LEL antibodies in the sera of subjects who are immune to O. volvulus were also shown to cross-react with rWbTSP LEL and rBmTSP LEL. These findings thus suggested that rTSP LEL can be developed as a potential vaccine candidate against multiple filarial infections.

Dakshinamoorthy, Gajalakshmi; Munirathinam, Gnanasekar; Stoicescu, Kristen; Reddy, Maryada Venkatarami; Kalyanasundaram, Ramaswamy

2013-01-01

119

Monitoring Freshwater Biodiversity at Large Scales: An Assessment of Potential Indicators  

NASA Astrophysics Data System (ADS)

Conservation of freshwater biodiversity is a priority for both government agencies and national and international conservation organizations. A number of large-scale conservation plans specifically targeting freshwater biodiversity have been, or will soon be, implemented across the globe. Although numerous potential biodiversity indicators have been proposed for monitoring the status of freshwater ecosystems, few of these indicators have been evaluated. Choice of indicator is especially problematic in many parts of the developing world, where biodiversity data are sparse in general and budgets are limited. In contrast, many developed countries have created freshwater biological assessment programs, which are generally based on measuring aspects of macroinvertebrate assemblages. However, macroinvertebrate-based assessments have not been generally applied to biodiversity conservation, and the extent to which macroinvertebrate-based measures reflect trends or responses in other taxa is unclear. We reviewed the extensive biodiversity and bioassessment literature to identify a practical set of biodiversity indicators for monitoring the success of freshwater conservation plans. After defining the properties that such indicators should possess, we concluded that no single extant indicator can adequately assess the biodiversity status of freshwater fauna. We highlight areas for further research and suggest combinatorial approaches that may prove adequate in the interim.

Simmons, T.; Hawkins, C. P.; Thieme, M.

2005-05-01

120

Gender Differences in Sexual Attitudes and Behaviors: A Review of Meta-Analytic Results and Large Datasets  

Microsoft Academic Search

Gender differences in sexual attitudes and behaviors are typically believed to be large, yet recent evidence suggests that some gender differences in sexuality are much smaller than common knowledge would suggest. This article reviews gender differences in sexual attitudes and behaviors as reported by major meta-analyses and large datasets. In particular, this article reviews gender differences in heterosexual intercourse, masturbation,

Jennifer L. Petersen; Janet Shibley Hyde

2011-01-01

121

A protein folding potential that places the native states of a large number of proteins near a local minimum  

Microsoft Academic Search

BACKGROUND: We present a simple method to train a potential function for the protein folding problem which, even though trained using a small number of proteins, is able to place a significantly large number of native conformations near a local minimum. The training relies on generating decoys by energy minimization of the native conformations using the current potential and using

Mukesh Chhajer; Gordon M Crippen

2002-01-01

122

Large differences in the diabatic heat budget of the tropical UTLS in reanalyses  

NASA Astrophysics Data System (ADS)

We present the time mean heat budgets of the tropical upper troposphere (UT) and lower stratosphere (LS) as simulated by five reanalysis models: MERRA, ERA-Interim, CFSR, JRA-25/JCDAS, and NCEP/NCAR. The simulated diabatic heat budget in the tropical UTLS differs significantly from model to model, with substantial implications for representations of transport and mixing. Large differences are apparent both in the net heat budget and in all comparable individual components, including latent heating, heating due to radiative transfer, and heating due to parameterised vertical mixing. We describe and discuss the most pronounced differences. Although they may be expected given difficulties in representing moist convection in models, the discrepancies in latent heating are still disturbing. We pay particular attention to discrepancies in radiative heating (which may be surprising given the strength of observational constraints on temperature and tropospheric water vapour) and discrepancies in heating due to turbulent mixing (which have received comparatively little attention).

Wright, J. S.; Fueglistaler, S.

2013-04-01

123

The measurement and evaluation of the contact potential difference between various powders and a metal  

Microsoft Academic Search

Experimental and theoretical studies were conducted on the measurement and evaluation of the contact potential difference between various powders and a metal. The apparent dielectric constant of the powder layer that appeared in the theory was also measured and compared with some theoretical models. It was confirmed that the apparent contact potential difference of a polymer powder is proportional to

Hiroaki Masuda; Takayuki Itakura; Kuniaki Gotoh; Tohru Takahashi; Takashi Teshima

1995-01-01

124

Precipitating electron fluxes formed by a magnetic field aligned potential difference  

Microsoft Academic Search

A model is developed in which a magnetic field aligned potential difference is assumed to accelerate electrons downward into the atmosphere. It is pointed out that the upgoing backscattered electrons produced by this electron beam may process insufficient kinetic energy to overcome the hypothetical potential difference. These electrons will be reflected downward to appear as members of a precipitating electron

David S. Evans

1974-01-01

125

Regulation of translational efficiency by different splice variants of the Disc large 1 oncosuppressor 5'-UTR.  

PubMed

Human Disc large (DLG1) has been demonstrated to be involved in the control of cell polarity and maintenance of tissue architecture, and is frequently lost in human tumours. However, the mechanisms controlling DLG1 expression are poorly understood. To further examine the regulation of DLG1 expression, we analysed the 5' ends of DLG1 transcripts by rapid amplification of cDNA ends polymerase chain reaction. We identified an alternative splicing event in the 5' region of DLG1 mRNA that generates transcripts with two different 5' untranslated regions (5'-UTRs). We show by reporter assays that the DLG1 5'-UTR containing an alternatively spliced exon interferes with the translation of a downstream open reading frame (ORF). However, no significant differences in mRNA stability among the DLG1 5'-UTR variants were observed. Sequence analysis of the additional exon present in the larger DLG1 5'-UTR showed the presence of an upstream short ORF which is lost in the short version of the 5'-UTR DLG1. By mutagenesis and luciferase assays, we analysed the contribution of this upstream short ORF in reducing translation efficiency, and showed that its disruption can revert, to some extent, the negative regulation of large 5'-UTR. Using computational modelling we also show that the large DLG1 5'-UTR isoform forms a more stable structure than the short version, and this may contribute to its ability to repress translation. This represents the first analysis of the 5' region of the DLG1 transcripts and shows that differential expression of alternatively spliced 5'-UTRs with different translational properties could result in changes in DLG1 abundance. PMID:21595829

Cavatorta, Ana L; Facciuto, Florencia; Valdano, Marina Bugnon; Marziali, Federico; Giri, Adriana A; Banks, Lawrence; Gardiol, Daniela

2011-06-13

126

Ultraviolet single-photons on demand and entanglement of photons with a large frequency difference  

SciTech Connect

We investigate an efficient scheme for generating ultraviolet single-photons ({approx}300 nm). The scheme combines the highly efficient single-photon four-wave mixing scheme and fast developing quantum dot single-photons on demand source technology. We show that near maximum, entanglement between two well matched ultraslowly propagating single-photon wave packets can be achieved. This study may lead to research and development opportunities in highly efficient entanglement schemes using photons of very large frequency difference, quantum information processing, and single-photon metrology and single-photon counting sensors in the uv spectra region.

Wu Ying [Electron and Optical Physics Division, NIST, Gaithersburg, Maryland 20899 (United States); State Key Laboratory for Laser Technique and Physics Department, Huazhong University of Science and Technology, Wuhan 430074 (China); Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071 (China); Payne, M.G.; Hagley, E.W.; Deng, L. [Electron and Optical Physics Division, NIST, Gaithersburg, Maryland 20899 (United States)

2004-12-01

127

Mirror Energy Differences at Large Isospin Studied through Direct Two-Nucleon Knockout.  

PubMed

The first spectroscopy of excited states in ^{52}Ni (T_{z}=-2) and ^{51}Co (T_{z}=-3/2) has been obtained using the highly selective two-neutron knockout reaction. Mirror energy differences between isobaric analogue states in these nuclei and their mirror partners are interpreted in terms of isospin nonconserving effects. A comparison between large-scale shell-model calculations and data provides the most compelling evidence to date that both electromagnetic and an additional isospin nonconserving interactions for J=2 couplings, of unknown origin, are required to obtain good agreement. PMID:23992059

Davies, P J; Bentley, M A; Henry, T W; Simpson, E C; Gade, A; Lenzi, S M; Baugher, T; Bazin, D; Berryman, J S; Bruce, A M; Diget, C Aa; Iwasaki, H; Lemasson, A; McDaniel, S; Napoli, D R; Ratkiewicz, A; Scruton, L; Shore, A; Stroberg, R; Tostevin, J A; Weisshaar, D; Wimmer, K; Winkler, R

2013-08-16

128

Mirror Energy Differences at Large Isospin Studied through Direct Two-Nucleon Knockout  

NASA Astrophysics Data System (ADS)

The first spectroscopy of excited states in Ni52 (Tz=-2) and Co51 (Tz=-3/2) has been obtained using the highly selective two-neutron knockout reaction. Mirror energy differences between isobaric analogue states in these nuclei and their mirror partners are interpreted in terms of isospin nonconserving effects. A comparison between large-scale shell-model calculations and data provides the most compelling evidence to date that both electromagnetic and an additional isospin nonconserving interactions for J=2 couplings, of unknown origin, are required to obtain good agreement.

Davies, P. J.; Bentley, M. A.; Henry, T. W.; Simpson, E. C.; Gade, A.; Lenzi, S. M.; Baugher, T.; Bazin, D.; Berryman, J. S.; Bruce, A. M.; Diget, C. Aa.; Iwasaki, H.; Lemasson, A.; McDaniel, S.; Napoli, D. R.; Ratkiewicz, A.; Scruton, L.; Shore, A.; Stroberg, R.; Tostevin, J. A.; Weisshaar, D.; Wimmer, K.; Winkler, R.

2013-08-01

129

Open circuit (mixed) potential changes upon contact between different inert electrodes-size and kinetic effects.  

PubMed

We investigate the principle of the open circuit potential (OCP) change upon a particle collision event based on mixed potential theory and confirmed by a mimic experiment in which we studied the changes in the OCP when two different electrodes (Pt and Au) are brought into contact in a solution that contains some irreversible redox couples. A micrometer-sized Au ultramicroelectrode, when connected in parallel to a Pt micro- or nanoelectrode, showed clearly measurable OCP changes whose magnitude matches well with that predicted by a simplified mixed potential theory for a pair of different electrode materials. On the basis of the study, each electrode establishes a different mixed potential involving two or more half reactions that have different heterogeneous electron transfer kinetics at different electrodes and the OCP changes are very sensitive to the relative ratio of the rate constant of the individual half reaction at different materials. PMID:23240811

Park, Jun Hui; Zhou, Hongjun; Percival, Stephen J; Zhang, Bo; Fan, Fu-Ren F; Bard, Allen J

2013-01-04

130

Potential temperature, upwelling rate and eclogite in the formation of the North Atlantic large igneous province  

NASA Astrophysics Data System (ADS)

The volumes and compositions of basalts generated by adiabatic decompression melting of the Earth’s mantle depend on mantle potential temperature (T_P), upwelling rate and the fertility of the mantle source. The relative importance of these factors in generating the high productivity magmatism of the Paleogene - Recent North Atlantic large igneous province (NAIP) remains controversial. Each has been proposed as a primary factor in the region. To assess the significance of these mechanisms in NAIP magmatism, we apply our forward melting model, REEBOX PRO, which simulates the melting of a heterogeneous source comprised of peridotite and eclogite lithologies. The model accounts for the thermodynamics of adiabatic decompression melting of a heterogeneous source using constraints from laboratory melting experiments. Input values of T_P and eclogite abundance are used to calculate the buoyancy of the mantle source and maximum upwelling rates. Source buoyancy constrains the maximum amount of eclogite in the mantle source that can ascend beneath the rift axis. All melts generated within the melting regime are pooled to form magmatic crust according to the residual column method. Using the model, variations in magmatic crustal thickness (from geophysics) as a function of eclogite content (from geochemistry) can be related to T_P and upwelling rate. Models with no thermal anomaly, that call on either enhanced upwelling rates due to plate separation (edge - driven convection) or the melting of abundant (> 30%) eclogite at “ambient” T_P (1325 °C), cannot generate the observed igneous crustal thicknesses around the province. Rather, elevated mantle T_P (minimum thermal anomaly ~ 85 - 195 °C) and associated buoyancy - driven upwelling are needed to explain the volume of igneous crust in the province. Involvement of eclogite, while necessary to explain the compositions of many NAIP lavas, does not significantly enhance melt production. These factors, coupled with the long history of high productivity magmatism in the region (~ 56 Ma), point toward a sustained thermal anomaly that is most likely conveyed from deeper mantle.

Brown, E. L.; Lesher, C. E.

2010-12-01

131

Large Differences in Aging Phenotype between Strains of the Short-Lived Annual Fish Nothobranchius furzeri  

PubMed Central

Background A laboratory inbred strain of the annual fish Nothobranchius furzeri shows exceptionally short life expectancy and accelerated expression of age markers. In this study, we analyze new wild-derived lines of this short-lived species. Methodology/Principal Findings We characterized captive survival and age-related traits in F1 and F2 offspring of wild-caught N. furzeri. Wild-derived N. furzeri lines showed expression of lipofuscin and neurodegeneration at age 21 weeks. Median lifespan in the laboratory varied from to 20 to 23 weeks and maximum lifespan from 25 to 32 weeks. These data demonstrate that rapid age-dependent decline and short lifespan are natural characteristics of this species. The N. furzeri distribution range overlaps with gradients in altitude and aridity. Fish from more arid habitats are expected to experience a shorter survival window in the wild. We tested whether captive lines stemming from semi-arid and sub-humid habitats differ in longevity and expression of age-related traits. We detected a clear difference in age-dependent cognitive decline and a slight difference in lifespan (16% for median, 15% for maximum lifespan) between these lines. Finally, we observed shorter lifespan and accelerated expression of age-related markers in the inbred laboratory strain compared to these wild-derived lines. Conclusions/Significance Owing to large differences in aging phenotypes in different lines, N. furzeri could represent a model system for studying the genetic control of life-history traits in natural populations.

Benedetti, Mauro; Roncaglia, Paola; Cattaneo, Antonino; Domenici, Luciano; Cellerino, Alessandro

2008-01-01

132

Milky Way potentials in cold dark matter and MOdified Newtonian Dynamics. Is the Large Magellanic Cloud on a bound orbit?  

Microsoft Academic Search

We compute the Milky Way potential in different cold dark matter (CDM) based models, and compare these with the MOdified Newtonian Dynamics (MOND) framework. We calculate the axial ratio of the potential in various models, and find that isopotentials are less spherical in MOND than in CDM potentials. As an application of these models, we predict the escape velocity as

Xufen Wu; Benoit Famaey; Gianfranco Gentile; Hagai Perets; Hongsheng Zhao

2008-01-01

133

Communication between multiple large earthquakes at different spatial scales across and beyond the Tibetan Plateau  

NASA Astrophysics Data System (ADS)

While seismicity is common on the Tibetan Plateau, the year 2008 was unusual in that several large dip-slip earthquakes occurred widely distributed across the Plateau. Four large primary normal faults (Mw 6.3 to 7.1) ruptured in different parts of the Plateau between January and October 2008, and the devastating Mw 7.9 thrust faulting Wenchuan earthquake occurred at the steep eastern margin in May. Another thrust event (Mw 6.3) occurred in the Qaidam Basin in November 2008, followed nine months later by a similar, shallower event at the same location. The extensional moment release in 2008 alone more than doubled that during the preceding 40 years. In this study we address possible reasons for this widespread seismicity in terms of triggering by other large events, exploring static and dynamic triggering from spatial scales of kilometres to thousands of kilometres. Static stress analysis can explain local clusters of earthquakes, for instance the four earthquakes (Mw 6.0-6.7) that occurred from 2004 to 2008 in Zhongba County. Stress models incorporating postseismic viscoelastic relaxation in addition to coseismic stress changes are consistent with the 1997 Mw 7.5 Manyi earthquake having triggered the 2001 Mw 7.9 Kokoxili earthquake ~200 km away by increasing stress near the hypocentre on a westerly splay of the main Kunlun fault rupture. We test whether quasi-static stress changes due to viscoelastic relaxation following these two large strike-slip earthquakes may have triggered some of the distant dip-slip events in 2008, and find that (a) only some of the events lie in areas of stress increase, and (b) the magnitude of the stress changes is very small (< 0.03 bars for the normal faults). We also investigate whether dynamic stresses from large earthquakes could have caused a transient weakening of the lower crust beneath the Plateau, resulting in an accelerated rate of interseismic motion and thus delayed triggering of earthquakes. Many lines of geophysical evidence suggest that the lower crust of Tibet is weakened by the presence of partial melts, and we explore whether large amplitude surface waves propagating across the Plateau may facilitate further localized or distributed weakening. We seek evidence for surface deformation transients and enhanced seismicity rates that may accompany such triggered episodes. Candidate source earthquakes are the Manyi and Kokoxili earthquakes on the Plateau itself and the 2004 Mw 9.2 Sumatra earthquake 2000 km away, whose rupture directivity was towards Tibet.

Ryder, I. M.; Burgmann, R.

2011-12-01

134

Kinematical evidence for physically different classes of large-scale coronal EUV waves  

NASA Astrophysics Data System (ADS)

Context. Large-scale wavelike disturbances have been observed in the solar corona in the EUV range since more than a decade. The physical nature of these so-called "EIT waves" is still being debated controversially. The two main contenders are on the one hand MHD waves and/or shocks, and on the other hand magnetic reconfiguration in the framework of an expanding CME. There is a lot of observational evidence backing either one or the other scenario, and no single model has been able to reproduce all observational constraints, which are partly even contradictory. This suggests that there may actually exist different classes of coronal waves that are caused by distinct physical processes. Then, the problems in interpreting coronal waves would be mainly caused by mixing together different physical processes. Aims: We search for evidence for physically different classes of large-scale coronal EUV waves. Methods: Kinematics is the most important characteristic of any moving disturbance, hence we focus on this aspect of coronal waves. Identifying distinct event classes requires a large event sample, which is up to now only available from SOHO/EIT. We analyze the kinematics of a sample of 176 EIT waves. In order to check if the results are severely affected by the low cadence of EIT, we complement this with high-cadence data for 17 events from STEREO/EUVI. In particular, we focus on the wave speeds and their evolution. Results: Based on their kinematical behavior, we find evidence for three distinct populations of coronal EUV waves: initially fast waves (v ? 320 km s-1) that show pronounced deceleration (class 1 events), waves with moderate (v ? 170-320 km s-1) and nearly constant speeds (class 2), and slow waves (v ? 130 km s-1) showing a rather erratic behavior (class 3). Conclusions: The kinematical behavior of the fast decelerating disturbances is consistent with nonlinear large-amplitude waves or shocks that propagate faster than the ambient fast-mode speed and subsequently slow down due to decreasing amplitude. The waves with moderate speeds are consistent with linear waves moving at the local fast-mode speed. Thus both populations can be explained in terms of the wave/shock model. The slow perturbations with erratic behavior, on the other hand, are not consistent with this scenario. These disturbances could well be due to magnetic reconfiguration.

Warmuth, A.; Mann, G.

2011-08-01

135

Generation and homodyne detection of continuous-variable entangled optical beams with a large wavelength difference  

NASA Astrophysics Data System (ADS)

We present a scheme for generating and homodyne detecting of continuous-variable entanglement of bright optical beams with a large wavelength difference by utilizing an optical parametric oscillator (OPO) and an optical parametric amplifier (OPA) simultaneously. Entangled optical beams at 0.8 and 1.5 ?m are generated from the OPA; the seed beams injected in the OPA as well as the local oscillators at the two wavelengths needed for homodyne detection are provided by the OPO. The entangler is a ring resonator involving a second-order nonlinear crystal that is pumped from two opposite directions. In one direction the pump power is above the oscillation threshold and the optical nonlinear resonator operates as an OPO. In the other direction the pump power is below the threshold and it operates as a phase-sensitive frequency nondegenerate optical parametric amplifier. Our scheme combines the advantages of both OPO and OPA quantum optical devices and opens another avenue for preparation and homodyne detection of high quality bright entangled light with a large wavelength difference.

Guo, Xiaomin; Xie, Changde; Li, Yongmin

2011-08-01

136

Generation and homodyne detection of continuous-variable entangled optical beams with a large wavelength difference  

SciTech Connect

We present a scheme for generating and homodyne detecting of continuous-variable entanglement of bright optical beams with a large wavelength difference by utilizing an optical parametric oscillator (OPO) and an optical parametric amplifier (OPA) simultaneously. Entangled optical beams at 0.8 and 1.5 {mu}m are generated from the OPA; the seed beams injected in the OPA as well as the local oscillators at the two wavelengths needed for homodyne detection are provided by the OPO. The entangler is a ring resonator involving a second-order nonlinear crystal that is pumped from two opposite directions. In one direction the pump power is above the oscillation threshold and the optical nonlinear resonator operates as an OPO. In the other direction the pump power is below the threshold and it operates as a phase-sensitive frequency nondegenerate optical parametric amplifier. Our scheme combines the advantages of both OPO and OPA quantum optical devices and opens another avenue for preparation and homodyne detection of high quality bright entangled light with a large wavelength difference.

Guo Xiaomin; Xie Changde; Li Yongmin [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China)

2011-08-15

137

Giant Aerosol Particles as a Potential Source of Supercooled Large Drops in Wintertime Stratiform Clouds  

NASA Astrophysics Data System (ADS)

Supercooled large drops (SLD) can pose a significant hazard for aviation because they tend to accumulate behind the leading edge of the wings where deicing mechanisms are lacking. Even when present in small amounts, SLD can cause significant ice buildup that degrades aircraft performance through decreased lift and increased drag. Multiple studies have demonstrated that warm rain processes are prevalent, or even dominant, in mixed-phase stratiform clouds containing SLD, but the formation mechanism for SLD has not been suitably demonstrated. We investigate the possibility that SLD form upon giant (diameter > 2m) aerosol particles, using observations collected with the National Center for Atmospheric Research's (NCAR) C130 aircraft during the second Alliance Icing Research Study (AIRSII). The observations are used to quantify and compare SLD in the clouds and giant aerosol particles in the clear air. Four of the six flights investigated have comparable numbers of SLD and giant aerosol particles; the other two flights have SLD concentrations several orders of magnitude less than the observed number of giant aerosol particles. No difference in the atmospheric or cloud conditions is found to explain the disparity in the results, but chemical analysis of collected giant aerosol particles reveals significant daily variability in their chemical composition. Surprisingly, the majority of giant aerosol particles collected on some flights were composed of salt. Backward air trajectories computed from the observation sites using numerical weather prediction model data suggest a local source of these giant salt particles rather than long-range transport from the oceans.

Lasher-Trapp, S.; Anderson-Bereznicki, S.; Twohy, C. H.

2005-12-01

138

How to know and choose online games: differences between current and potential players.  

PubMed

This study investigated how different adolescent players acquire game information and the criteria they use in choosing online games and found that (1) current players generally use comprehensive information sources more than potential players do; (2) current players rely on free trials and smooth display of motion graphics as choice criteria more than potential players do; (3) potential players rely on the look of advertisements more than current players do; (4) both current and potential players most likely use word-of-mouth and gaming programs on TV as information sources; and (5) endorser attractiveness is ranked the least important among six choice criteria by both current and potential players. PMID:18085974

Teng, Ching-I; Lo, Shao-Kang; Wang, Pe-Cheng

2007-12-01

139

Use of an Automatic Methane Potential Test System for evaluating the biomethane potential of sugarcane bagasse after different treatments.  

PubMed

A multi-channel analyzer was used to evaluate biogas potential of sugarcane bagasse (SCB). The Automatic Methane Potential Test System contained fifteen parallel reactors and the same number of gas flow meters attached to the acquisition system. The set of reactors - gas flow meters gave reproducible results during anaerobic digestion of chemically defined carbon source and the units were used to evaluate the biomethane potential of SCB after different pretreatments, such as treatment with water, acid, acid followed by enzymatic treatment and acid followed by treatment with inactive enzymes. Combined pretreatment with 2% sulphuric acid and enzymatic hydrolysis (3.5% enzymes) resulted in conversion of 79% to monomeric sugars present in SCB. SCB treated with acid followed by enzymatic hydrolysis achieved the methane yield of 200 NL per kg VS(added). Enzymatic saccharification of acid pretreated SCB resulted in increase of methane yield by 16±5% compared to that from acid treated SCB. PMID:22446055

Badshah, Malik; Lam, Duong Minh; Liu, Jing; Mattiasson, Bo

2012-03-03

140

Forecasting Ocean Uptake of CO2: A Small Difference Between Large Numbers  

NASA Astrophysics Data System (ADS)

It is incredible how well we know present and past carbon cycle budgets (including the ocean uptake of CO2), based on observed atmospheric CO2 time series, emission inventories, and precise isotopic and O/N measurements. But none of these can be used to forecast future oceanic CO2 uptake. Neither can paleo variations: the inhabited Earth has never experienced this much greenhouse forcing. To forecast uptake, we need to compute a small difference between large numbers: about 92 PgC into and 90 PgC out of the ocean annually. The IPCC acknowledges that these gross fluxes are uncertain to 20 percent (at best), but does not note the ramifications of this uncertainy. We show here that as little as a 3 percent change in emission and deposition fluxes (globally averaged over countless regional chemical and physical variations) could double the rate of atmospheric CO2 increase or just as easily change its sign to a net CO2 ocean emission. This is not a forecast, of course, but a simple sensitivity analysis. At the moment we cannot be certain even what the sign of the net ocean CO2 flux will be in a few decades. Most of the research done so far cannot improve on this alarming uncertainty, because past fluxes can not be extrapolated into a non-linear future. This small difference is a very large loose cannon. It is critical that vastly increased attention be given to quantifying the factors that control both exchange velocities and delta-pCO2 values. The goal should be that each factor is well enough quantified that at least the functional form of its impact on exchange fluxes can be incorporated into regionally-specific climate models. Improving exchange velocity models requires the development of instruments that can complement the current LiCor instruments at measuring CO2 fluxes via eddy covariance, with fewer (or at least different) sensitivity and noise problems. Viable options exist.

Huebert, B. J.

2007-12-01

141

Olfactory Event-Related Potentials Reflect Individual Differences in Odor Valence Perception  

Microsoft Academic Search

Investigating the neural substrates of perceived quality in olfaction using different odorants is intrinsically difficult. By utilizing individual differences in perceived quality of the odor of androstenone, we obtained a continuum of individual differences in rated valence of the same stimulus allowing investigations of its manifestation in the olfactory event-related potentials (ERPs). In an initial group consisting of 43 individuals

Johan N. Lundstrom; Suzi Seven; Mats J. Olsson; Benoist Schaal; Thomas Hummel

2006-01-01

142

Alternative transcription start site selection leads to large differences in translation activity in yeast.  

PubMed

mRNA levels do not accurately predict protein levels in eukaryotic cells. To investigate contributions of 5' untranslated regions (5' UTRs) to mRNA-specific differences in translation, we determined the 5' UTR boundaries of 96 yeast genes for which in vivo translational efficiency varied by 80-fold. A total of 25% of genes showed substantial 5' UTR heterogeneity. We compared the capacity of these genes' alternative 5' UTR isoforms for cap-dependent and cap-independent translation using quantitative in vitro and in vivo translation assays. Six out of nine genes showed mRNA isoform-specific translation activity differences of greater than threefold in at least one condition. For three genes, in vivo translation activities of alternative 5' UTR isoforms differed by more than 100-fold. These results show that changing genes' 5' UTR boundaries can produce large changes in protein output without changing the overall amount of mRNA. Because transcription start site (TSS) heterogeneity is common, we suggest that TSS choice is greatly under-appreciated as a quantitatively significant mechanism for regulating protein production. PMID:23105001

Rojas-Duran, Maria F; Gilbert, Wendy V

2012-10-25

143

Three different group I introns in the nuclear large subunit ribosomal DNA of the amoeboflagellate Naegleria.  

PubMed Central

We have amplified the large subunit ribosomal DNA (LSUrDNA) of the 12 described Naegleria spp. and of 34 other Naegleria lineages that might be distinct species. Two strains yielded a product that is longer than 3 kb, which is the length of the LSUrDNA of all described Naegleria spp. Sequencing data revealed that the insert in one of these strains is a group I intron without an open reading frame (ORF), while the other strain contains two different group I introns, of which the second intron has an ORF of 175 amino acids. In the latter ORF there is a conserved His-Cys box, as in the homing endonucleases present in group I introns in the small subunit ribosomal DNA (SSUrDNA) of Naegleria spp. Although the group I introns in the LSUrDNA differ in sequence, they are more related to each other than they are to the group I introns in the SSUrDNA of Naegleria spp. The three group I introns in the LSUrDNA in Naegleria are at different locations and are probably acquired by horizontal transfer, contrary to the SSUrDNA group I introns in this genus which are of ancestral origin and are transmitted vertically.

De Jonckheere, J F; Brown, S

1998-01-01

144

A comparison of crystal–melt interfacial free energies using different Al potentials  

Microsoft Academic Search

We have calculated the crystal–melt interfacial stiffnesses using simulations with three different interatomic potentials for Al, and from these derived the anisotropic crystal–melt interfacial free energies. We find that there is a strong dependence of the results on the potential, and that this dependence cannot be explained by the usual Turnbull relation between the interfacial free energy and the latent

James R. Morris; Mikhail I. Mendelev; D. J. Srolovitz

2007-01-01

145

Relationship between Visual Evoked Potentials and Subjective Differences between Emotional Expressions in “Face Diagrams”  

Microsoft Academic Search

The relationship between visual evoked potentials resulting from substitution of one image of a human “face diagram” for another and assessment of perceived differences between the emotional expressions of these faces were studied. Emotions were altered by changing the curvature of the mouth and\\/or the slope of the brows. Unlike the traditional approach, in which visual evoked potentials are recorded

Ch. A. Izmailov; S. G. Korshunova; E. N. Sokolov

2001-01-01

146

A numerical study of the large-period limit of a Zakharov-Shabat eigenvalue problem with periodic potentials  

NASA Astrophysics Data System (ADS)

Deconinck and Kutz (2006 J. Comput. Phys. 219 296-321) developed an efficient algorithm for solving the Zakharov-Shabat eigenvalue problem with periodic potentials numerically. It is natural to use the same algorithm for solving the problem for non-periodic potential (decaying potentials defined over the whole real line) using large periods. In this paper, we propose the use of a specific value of the Floquet exponent. Our numerical results indicate that it can produce accurate results long before the period becomes large enough for the analytical convergence results of Gardner (1997 J. Reine Angew. Math. 491 149-81) to be valid. We also illustrate the rather complicated path to convergence of some nonlinear Schrödinger potentials.

Olivier, C. P.; Herbst, B. M.; Molchan, M. A.

2012-06-01

147

Effect of photoelectrons on boom-satellite potential differences during electron beam ejection  

SciTech Connect

Data taken on the SCATHA satellite at geosynchronous altitudes during periods of electron beam ejection in sunlight showed that the potential difference between an electrically isolated boom and the satellite main body was a function of beam current, energy, and boom-sun angle. The potential difference decreased as the boom area illuminated by the sun increased; the maximum and minimum potential differences were measured when minimum and maximum boom areas, respectively, were exposed to the sun. It is shown that photoelectrons, created on the boom, could be engulfed in the electrostatic field of the highly charged satellite main body. Theoretical calculations made using a simple current balance model showed that these electrons could provide a substantial discharging current to the main body and cause the observed variations in the potential difference between the main body and the booms. copyright American Geophysica Union 1987

Lai, S.T.; Cohen, H.A.; Aggson, T.L.; McNeil, W.J.

1987-11-01

148

Characterization of Nasal Potential Difference in cftr Knockout and F508del-CFTR Mice  

PubMed Central

Background Treatments designed to correct cystic fibrosis transmembrane conductance regulator (CFTR) defects must first be evaluated in preclinical experiments in the mouse model of cystic fibrosis (CF). Mice nasal mucosa mimics the bioelectric defect seen in humans. The use of nasal potential difference (VTE) to assess ionic transport is a powerful test evaluating the restoration of CFTR function. Nasal VTE in CF mice must be well characterized for correct interpretation. Methods We performed VTE measurements in large-scale studies of two mouse models of CF—B6;129 cftr knockout and FVB F508del-CFTR—and their respective wild-type (WT) littermates. We assessed the repeatability of the test for cftr knockout mice and defined cutoff points distinguishing between WT and F508del-CFTR mice. Results We determined the typical VTE values for CF and WT mice and demonstrated the existence of residual CFTR activity in F508del-CFTR mice. We characterized intra-animal variability in B6;129 mice and defined the cutoff points for F508del-CFTR chloride secretion rescue. Hyperpolarization of more than -2.15 mV after perfusion with a low-concentration Cl- solution was considered to indicate a normal response. Conclusions These data will make it possible to interpret changes in nasal VTE in mouse models of CF, in future preclinical studies.

Saussereau, Emilie Lyne; Roussel, Delphine; Diallo, Siradiou; Debarbieux, Laurent; Edelman, Aleksander; Sermet-Gaudelus, Isabelle

2013-01-01

149

Large genomic differences between the morphologically indistinguishable diplomonads Spironucleus barkhanus and Spironucleus salmonicida  

PubMed Central

Background Microbial eukaryotes show large variations in genome structure and content between lineages, indicating extensive flexibility over evolutionary timescales. Here we address the tempo and mode of such changes within diplomonads, flagellated protists with two nuclei found in oxygen-poor environments. Approximately 5,000 expressed sequence tag (EST) sequences were generated from the fish commensal Spironucleus barkhanus and compared to sequences from the morphologically indistinguishable fish parasite Spironucleus salmonicida, and other diplomonads. The ESTs were complemented with sequence variation studies in selected genes and genome size determinations. Results Many genes detected in S. barkhanus and S. salmonicida are absent in the human parasite Giardia intestinalis, the most intensively studied diplomonad. For example, these fish diplomonads show an extended metabolic repertoire and are able to incorporate selenocysteine into proteins. The codon usage is altered in S. barkhanus compared to S. salmonicida. Sequence variations were found between individual S. barkhanus ESTs for many, but not all, protein coding genes. Conversely, no allelic variation was found in a previous genome survey of S. salmonicida. This difference was confirmed by sequencing of genomic DNA. Up to five alleles were identified for the cloned S. barkhanus genes, and at least nineteen highly expressed S. barkhanus genes are represented by more than four alleles in the EST dataset. This could be explained by the presence of a non-clonal S. barkhanus population in the culture, by a ploidy above four, or by duplications of parts of the genome. Indeed, genome size estimations using flow cytometry indicated similar haploid genome sizes in S. salmonicida and G. intestinalis (~12 Mb), whereas the S. barkhanus genome is larger (~18 Mb). Conclusions This study indicates extensive divergent genome evolution within diplomonads. Genomic traits such as codon usage, frequency of allelic sequence variation, and genome size have changed considerably between S. barkhanus and S. salmonicida. These observations suggest that large genomic differences may accumulate in morphologically indistinguishable eukaryotic microbes.

2010-01-01

150

The determination of gravitational potential differences from satellite-to-satellite tracking  

Microsoft Academic Search

A new, rigorous model is developed for the difference of gravitational potential between two close earth-orbiting satellites\\u000a in terms of measured range-rates, velocities and velocity differences, and specific forces. It is particularly suited to regional\\u000a geopotential determination from a satellite-to-satellite tracking mission. Based on energy considerations, the model specifically\\u000a accounts for the time variability of the potential in inertial space,

Christopher Jekeli

1999-01-01

151

The Contribution Potential of Glaciers and Snow Cover to River Runoff in Different Climate Regimes  

NASA Astrophysics Data System (ADS)

Glaciers and seasonal snow cover are expected to change their water storage capacity under the changing climate conditions. The potential to modify river runoff of both the storage capacity and its variability differs in different climate regimes and decreases downriver. The lack of appropriate data records and model performance leaves us with only vague ideas for most river systems worldwide. We present a simple method to assess the contribution potential of glaciers and seasonal snow cover to river runoff from data sets available worldwide. Respective results are presented in simple and worldwide comparable plots. Examples are given for major river systems in different latitudes and on different continents.

Kaser, G.; Grosshauser, M.; Marzeion, B.

2009-12-01

152

When species' ranges meet: assessing differences in habitat selection between sympatric large carnivores.  

PubMed

Differentiation in habitat selection among sympatric species may depend on niche partitioning, species interactions, selection mechanisms and scales considered. In a mountainous area in Sweden, we explored hierarchical habitat selection in Global Positioning System-collared individuals of two sympatric large carnivore species; an obligate predator, the Eurasian lynx (Lynx lynx), and a generalist predator and scavenger, the wolverine (Gulo gulo). Although the species' fundamental niches differ widely, their ranges overlap in this area where they share a prey base and main cause of mortality. Both lynx and wolverines selected for steep and rugged terrain in mountainous birch forest and in heaths independent of scale and available habitats. However, the selection of lynx for their preferred habitats was stronger when they were forming home ranges and they selected the same habitats within their home ranges independent of home range composition. Wolverines displayed a greater variability when selecting home ranges and habitat selection also varied with home range composition. Both species selected for habitats that promote survival through limited encounters with humans, but which also are rich in prey, and selection for these habitats was accordingly stronger in winter when human activity was high and prey density was low. We suggest that the observed differences between the species result primarily from different foraging strategies, but may also depend on differences in ranging and resting behaviour, home range size, and relative density of each species. Our results support the prediction that sympatric carnivores with otherwise diverging niches can select for the same resources when sharing main sources of food and mortality. PMID:23242426

Rauset, Geir Rune; Mattisson, Jenny; Andrén, Henrik; Chapron, Guillaume; Persson, Jens

2012-12-14

153

The potential of large-scale open-sea cultivation of benthic algae  

Microsoft Academic Search

There is an area of open water about 200 miles long and 20 miles wide along the Florida Gulf coast that is eminently adapted to large-scale mariculture of tropical benthic algae. It is suggested that this is a unique area for the development of a large-scale system of planting, harvesting, and processing certain fast-growing tropical marine algae of value as

H. J. Humm

1979-01-01

154

Age-Dependent Telomere Attrition as a Potential Indicator of Racial Differences in Renal Growth Patterns  

Microsoft Academic Search

Background: Racial differences in the predilection to salt sensitivity may arise from different renal growth patterns. To test this idea, we monitored age-dependent telomere attrition rate, reflecting largely the replicative history of somatic cells, in the outer renal cortex and the inner renal medulla of African Americans and Caucasians. Methods: Telomere length, determined by the mean length of the terminal

L. Tchakmakjian; J. P. Gardner; P. D. Wilson; M. Kimura; J. Skurnick; H. R. Zielke; A. Aviv

2004-01-01

155

Sex Differences on "g" and Non-"g" Intellectual Performance Reveal Potential Sources of STEM Discrepancies  

ERIC Educational Resources Information Center

|The analysis of sex differences in cognitive abilities is largely confusing because these differences are masked by the pervasive influence of the general factor of intelligence (g). In this study a battery of five reasoning tests (abstract [AR], numerical [NR], verbal [VR], mechanical [MR], and spatial [SR]) was completed by a sample of 3233…

Lemos, Gina C.; Abad, Francisco J.; Almeida, Leandro S.; Colom, Roberto

2013-01-01

156

Analytical solitary-wave solutions of the generalized nonautonomous cubic-quintic nonlinear Schroedinger equation with different external potentials  

SciTech Connect

A large family of analytical solitary wave solutions to the generalized nonautonomous cubic-quintic nonlinear Schroedinger equation with time- and space-dependent distributed coefficients and external potentials are obtained by using a similarity transformation technique. We use the cubic nonlinearity as an independent parameter function, where a simple procedure is established to obtain different classes of potentials and solutions. The solutions exist under certain conditions and impose constraints on the coefficients depicting dispersion, cubic and quintic nonlinearities, and gain (or loss). We investigate the space-quadratic potential, optical lattice potential, flying bird potential, and potential barrier (well). Some interesting periodic solitary wave solutions corresponding to these potentials are then studied. Also, properties of a few solutions and physical applications of interest to the field are discussed. Finally, the stability of the solitary wave solutions under slight disturbance of the constraint conditions and initial perturbation of white noise is discussed numerically; the results reveal that the solitary waves can propagate in a stable way under slight disturbance of the constraint conditions and the initial perturbation of white noise.

He Junrong; Li Huamei [Department of Physics, Zhejiang Normal University, Jinhua, Zhejiang 321004 (China)

2011-06-15

157

Potential of mean force of association of large hydrophobic particles: towards the nanoscale limit  

PubMed Central

The potentials of mean force (PMFs) were determined, in both water with the TIP3P water model and in vacuo, for systems involving formation of nonpolar dimers composed of bicyclooctane, adamantane (both an all-atom model and a sphere with the radius of 3.4 Å representing adamantane), and fullerene, respectively. A series of umbrella-sampling molecular dynamics simulations with the AMBER force field were carried out for each pair, under both environmental conditions. The PMFs were calculated by using the Weighted Histogram Analysis Method (WHAM). The results were compared with our previously-determined PMF for neopentane. The shape of the PMFs for dimers of all four nonpolar molecules is characteristic of hydrophobic interactions with contact and solvent-separated minima, and desolvation maxima. The positions of all these minima and maxima change with the size of the nonpolar molecule; for larger molecules they shift toward larger distances. Comparison of the PMFs of the bicyclooctane, adamantane, and fullerene dimers in water and in vacuo shows that hydrophobic interactions in each dimer are different from that for the dimer of neopentane. Interactions in the bicyclooctane, adamantane, and fullerene dimers are stronger in vacuo than in water. These dimers cannot be treated as classical spherical hydrophobic objects. The solvent contribution to the PMF was also computed by subtracting the PMF determined in vacuo from that in explicit solvent. The solvent contribution to the PMFs of bicyclooctane, adamantane, and fullerene is positive as opposed to that of neopentane. The water molecules in the first solvation sphere of both adamantane and neopentane dimers are more ordered compared to bulk water, with their dipole moments pointing away from the surface of the dimers. The average number of hydrogen bonds per water molecule in the first hydration shell of adamantane is smaller compared to that in bulk water, but this shell is thicker for all-atom adamantane than for neopentane or a spherical model of adamantane. In the second hydration shell, the average number of hydrogen bonds is greater compared to that in bulk water only for neopentane and a spherical model of adamantane but not for the all-atom model. The strength of the hydrophobic interactions shows a linear dependence on the number of carbon atoms both in water and in vacuo. Smaller nonpolar particles interact more strongly in water than in vacuo. For larger molecules such as bicyclooctane, adamanatane and fullerene, the reversed tendency is observed.

Makowski, Mariusz; Czaplewski, Cezary; Liwo, Adam; Scheraga, Harold A.

2010-01-01

158

Evaluation of light regulatory potential of Calvin cycle steps based on large-scale gene expression profiling data  

Microsoft Academic Search

Although large-scale gene expression data have been studied from many perspectives, they have not been systematically integrated to infer the regulatory potentials of individual genes in specific pathways. Here we report the analysis of expression patterns of genes in the Calvin cycle from 95 Arabidopsis microarray experiments, which revealed a consistent gene regulation pattern in most experiments. This identified pattern,

Ning Sun; Ligeng Ma; Deyun Pan; Hongyu Zhao; Xing Wang Deng

2003-01-01

159

Large Vestibular Evoked Myogenic Potentials in Response to Bone-Conducted Sounds in Patients with Superior Canal Dehiscence Syndrome  

Microsoft Academic Search

Dehiscence of the superior semicircular canal is a ‘new’ vestibular entity. Among these patients, the vestibular evoked myogenic potentials (VEMP) in response to air-conducted sounds are large. In the present study, VEMP in response to bone-conducted sounds were studied in 5 normal subjects, in 3 patients after (unilateral) labyrinthectomy and in 4 patients with (unilateral) superior canal dehiscence syndrome. The

Krister Brantberg; Lennart Löfqvist; Per-Anders Fransson

2004-01-01

160

Registration of N6202 soybean germplasm with high protein, good yield potential, large seed and diverse pedigree  

Technology Transfer Automated Retrieval System (TEKTRAN)

‘N6202’ soybean [Glycine max (L.,) Merr.] was cooperatively developed and released by the USDA-ARS and the North Carolina Agricultural Research Service in 2009 as a Maturity Group VI germplasm with high-protein seed, good yield potential, large-seed size, and diverse pedigree. The unusual combinati...

161

Mechanism of large oscillations of anodic potential during anodization of silicon in H 3PO 4\\/HF solutions  

Microsoft Academic Search

Effect of large oscillations of electrical potential during anodic polarization of silicon in electrolytes composed of phosphoric and hydrofluoric acids has been reported. The oscillations last hours without damping if experimental conditions are optimal. Changes of temperature, anodic current density, intensity of stirring, etc. quench them or convert into less periodic ones. The oscillations are of very high amplitude (typically

V Parkhutik; E Matveeva; R Perez; J Alamo; D Beltrán

2000-01-01

162

Landslide is a Landslide is a Landslide...Or Is It. Defining Landslide Potential Across Large Landscapes.  

National Technical Information Service (NTIS)

Not all landslides are created equal. Some have the potential to run out to streams and others do not. Some are likely to simplify and damage stream habitat, and others can be important sources of gravel and large wood, fundamental components of habitat c...

K. Burnett

2008-01-01

163

Structure of different within-plate magmatic system of large igneous provinces  

NASA Astrophysics Data System (ADS)

It is generally accepted that formation of continental large igneous provinces (LIPs) is linked with ascending of mantle superplumes. However, it is not clear yet why and how magmatic systems appeared and functionated. It is known that LIPs are formed by numerous magmatic centers, which imply existence of individual magmatic systems beneath them. Such a situation can be explained by presence of protuberances (local plumes) on the surface of extended superplume heads, where processes of adiabatic melting occurred give rise to formation of magmatic systems. Newly-formed melts on their way to the surface pass through complicate system of conduits and transitional magma chambers, where they were undergone by different processes of crystallizing differentiation, mixing, assimilation of wall-rocks, etc. According to data available, three major levels of transitional magmatic chambers, linked by systems of feeder conduits (dikes), occurred within the crust. Each of them is responsible for transformation of a primary melt in different extent: The lowest level with the largest chambers, located along boundary between upper margin of the plume head and incumbent rigid lithosphere; they are responsible for the underplating phenomenon. Processes of contamination mantle-derived magmas by crustal material can play essential role here, especially in the late Archean and early Paleoproterozoic when they led to appearance of specific mantle-crustal magmas of siliceous high-Mg series (SHMS), which formed large igneous provinces with numerous mafic-iltramafic layered intrusions (Sharkov, Bogina, 2006). It suggests that formation of this series was linked with "floating up" of chambers (batches) of high-temperature ultramafic magmas through the upper part of lithospheric mantle and mafic lower crust by zone refinement mechanism, i.e. by melting material of the chamber's roof and crystallization at their bottoms. As a result, the primary melt gradually enriched in crustal material; portions of such series of melts periodically arrived into hardening transitional magma chambers of the middle level. Very likely that such structure of magmatic systems was typical also for the earliest Moon's magnesian suite magmatism, where such type layered mafic-ultramafic intrusions was found (Snyder et al., 1995). (2) Processes at the middle level are easy to understand on example of large layered mafic-ultramafic intrusions which are represent hardened transition magma chambers. Crystallizing differentiation as well as mixing of periodically arrived into hardening intrusive chambers fresh portions of magmas with evolved melts in it occurred here. Specific type of transitional magma chambers are represented by huge bimodal anorthosite-rapakivi granite complexes (ARGCs), typical for the Mesoproterozoic. They were formed under conditions of unusually thick (70-80 km at the moment) continental crust. Geological, geochemical and isotope data evidence that melting in the mantle and silicic crust occurred here simultaneously above local mantle plumes. It suggests that melting of the crust's material occurred above sill-like intrusions of basaltic melt which were led to appearance of large magma chambers, where mafic and sialic melts coexisted; such chambers represented now as ARGCs. By contrast to continental crust, under conditions of thin oceanic crust processes at the low and middle levels of magmatic systems are united, and layered mafic-ultramafic intrusions occurred directly between the ultramafic mantle and rocks of the upper crust, play role of the lower oceanic crust, how it is easily to observe on example of ophiolite associations. (3) The shallow level - subvolcanic chambers (usually sills), from which melts arrive to the surface, forming individual volcanoes and lava plateaus. Processes of contamination of wall rocks and crystallizing differentiation are very limited here due to small size of bodies and, accordingly, low heat keeping and quickly hardening. So, primary magmatic melt can reach the surface very rare; as a rule, it had undergone

Sharkov, E.

2009-04-01

164

Tetraploid and hexaploid wheat varieties reveal large differences in expression of alpha-gliadins from homoeologous Gli-2 loci  

PubMed Central

Background ?-gliadins form a multigene protein family encoded by multiple ?-gliadin (Gli-2) genes at three genomic loci, Gli-A2, Gli-B2 and Gli-D2, respectively located on the homoeologous wheat chromosomes 6AS, 6BS, and 6DS. These proteins contain a number of important celiac disease (CD)-immunogenic domains. The ?-gliadins expressed from the Gli-B2 locus harbour fewer conserved CD-epitopes than those from Gli-A2, whereas the Gli-D2 gliadins have the highest CD-immunogenic potential. In order to detect differences in the highly CD-immunogenic ?-gliadin fraction we determined the relative expression level from the homoeologous Gli-2 loci in various tetraploid and hexaploid wheat genotypes by using a quantitative pyrosequencing method and by analyzing expressed sequence tag (EST) sequences. Results We detected large differences in relative expression levels of ?-gliadin genes from the three homoeologous loci among wheat genotypes, both as relative numbers of expressed sequence tag (EST) sequences from specific varieties and when using a quantitative pyrosequencing assay specific for Gli-A2 genes. The relative Gli-A2 expression level in a tetraploid durum wheat cultivar ('Probstdorfer Pandur') was 41%. In genotypes derived from landraces, the Gli-A2 frequency varied between 12% and 58%. In some advanced hexaploid bread wheat cultivars the genes from locus Gli-B2 were hardly expressed (e.g., less than 5% in 'Lavett') but in others they made up more than 40% (e.g., in 'Baldus'). Conclusion Here, we have shown that large differences exist in relative expression levels of ?-gliadins from the homoeologous Gli-2 loci among wheat genotypes. Since the homoelogous genes differ in the amount of conserved CD-epitopes, screening for differential expression from the homoeologous Gli-2 loci can be employed for the pre-selection of wheat varieties in the search for varieties with very low CD-immunogenic potential. Pyrosequencing is a method that can be employed for such a 'gene family-specific quantitative transcriptome profiling'.

Salentijn, Elma MJ; Goryunova, Svetlana V; Bas, Noor; van der Meer, Ingrid M; van den Broeck, Hetty C; Bastien, Thomas; Gilissen, Luud JWJ; Smulders, Marinus JM

2009-01-01

165

Implicit Large Eddy Simulation of Flow over a Corrugated Dragonfly Wing Using High-Order Spectral Difference Method  

NASA Astrophysics Data System (ADS)

Implicit large eddy simulations of flow over a corrugated dragonfly wing at a Reynolds number of 34,000 at high angles of attack have been investigated with a high-order unstructured spectral difference Navier-Stokes solver. The computational results are compared with a recent experimental study by Hu et al. Both 2D and 3D simulations are carried out to assess how realistic and reliable the 2D simulations are in comparison with 3D simulations. At the angle of attack of 16 degrees, the 2D simulation failed to predict the stall observed in the experiment, while the 3D simulation correctly predicted the stall. In addition, the 3D simulation predicted a mean lift coefficient within 5% of the experimental data. We plan to compute at least another angle of attack and compare with the experimental data. The numerical simulations demonstrated the potential of the high-order SD method in large eddy simulation of physically complex problems.

Wang, Z. J.

2009-11-01

166

Transepithelial potential differences and sodium fluxes in isolated perfused gills of the mangrove crab Ucides cordatus  

Microsoft Academic Search

Marked differences in transepithelial potential difference (TEP) and unidirectional sodium fluxes were observed in isolated, perfused posterior gills 5 and 6 of the hyper–hyporegulating crab Ucides cordatus. Gills were perfused with a saline which closely matched the composition of the crab's haemolymph, and bathed with 9, 17, 26 and 34‰ seawater (SW). In 26‰ SW, TEPs were small and similar

C. B. R. Martinez; R. R. Harris; M. C. F. Santos

1998-01-01

167

Interannual variation in climate-potential net primary productivity relationships in differing ecosystems of California  

Microsoft Academic Search

The seasonality and interannual variation in potential net primary production (NPP) were examined in differing vegetation types in California over three years of contrasting precipitation using co-registered maps of climate, vegetation, and 1km biweekly NDVI derived from high resolution satellite AVHRR data. Differences in seasonality of the vegetation types (annual grassland, chamise chaparral, deciduous oak woodland, and evergreen oak) were

G. W. Koch; J. T. Randerson

1994-01-01

168

A tale of two skyrmions: The nucleon's strange quark content in different large N c limits  

Microsoft Academic Search

The nucleon's strange quark content comes from closed quark loops, and hence should vanish at leading order in the traditional large Nc (TLNC) limit. Quark loops are not suppressed in the recently proposed orientifold large Nc (OLNC) limit, and thus the strange quark content should be non-vanishing at leading order. The Skyrme model is supposed to encode the large Nc

Aleksey Cherman; Thomas D. Cohen

2006-01-01

169

Gender differences in sexual attitudes and behaviors: a review of meta-analytic results and large datasets.  

PubMed

Gender differences in sexual attitudes and behaviors are typically believed to be large, yet recent evidence suggests that some gender differences in sexuality are much smaller than common knowledge would suggest. This article reviews gender differences in sexual attitudes and behaviors as reported by major meta-analyses and large datasets. In particular, this article reviews gender differences in heterosexual intercourse, masturbation, pornography use, attitudes toward premarital sex, and gender differences in same-gender sexuality. Evolutionary psychology, social cognitive learning theory, and social structural theory are explored as possible explanations for gender differences in sexuality. PMID:21409712

Petersen, Jennifer L; Hyde, Janet Shibley

2011-03-01

170

Potential impacts of precipitation change on large-scale patterns of tree diversity  

Microsoft Academic Search

Forests are globally important ecosystems host to outstanding biological diversity. Widespread efforts have addressed the impacts of climate change on biodiversity in these ecosystems. We show that a metacommunity model founded on basic ecological processes offers direct linkage from large-scale forcing, such as precipitation, to tree diversity patterns of the Mississippi-Missouri River System and its subregions. We quantify changes in

M. Konar; R. Muneepeerakul; S. Azaele; E. Bertuzzo; A. Rinaldo; I. Rodriguez-Iturbe

2010-01-01

171

Clustering of Tropopause Penetrating Clouds: A Potential Test of Large-scale Convection in Climate Models  

Microsoft Academic Search

Advanced Infrared Sounder (AIRS) data taken with a 13 km diameter field of view show the presence of thousands of cloud-tops colder than 210 K each day in the tropical oceans. Based on spectrally resolved water lines in the upper troposphere and lower stratosphere a large fraction of these deep convective clouds penetrates the tropopause and thus become Tropopause Penetrating

H. H. Aumann; A. Ruzmaikin; S. G. Desouza-Machado

2009-01-01

172

Giant Aerosol Particles as a Potential Source of Supercooled Large Drops in Wintertime Stratiform Clouds  

Microsoft Academic Search

Supercooled large drops (SLD) can pose a significant hazard for aviation because they tend to accumulate behind the leading edge of the wings where deicing mechanisms are lacking. Even when present in small amounts, SLD can cause significant ice buildup that degrades aircraft performance through decreased lift and increased drag. Multiple studies have demonstrated that warm rain processes are prevalent,

S. Lasher-Trapp; S. Anderson-Bereznicki; C. H. Twohy

2005-01-01

173

Ethnic differences in cytokine gene polymorphisms: potential implications for cancer development  

Microsoft Academic Search

Differences in incidence and outcome of cancer among ethnic groups may be explained by biological and\\/or socio-economic factors.\\u000a Genetic variations that affect chronic inflammation, a potentially important risk factor for carcinogenesis, may differ across\\u000a ethnic groups. Such differences may help explain cancer disparities among these groups. Single nucleotide polymorphisms (SNPs)\\u000a within cytokine genes can affect cytokine levels and the degree

Jovanny Zabaleta; Barbara G. Schneider; Kelli Ryckman; Pleasant F. Hooper; M. Constanza Camargo; M. Blanca Piazuelo; Rosa A. Sierra; Elizabeth T. H. Fontham; Pelayo Correa; Scott M. Williams; Augusto C. Ochoa

2008-01-01

174

Active and total microbial communities in forest soil are largely different and highly stratified during decomposition  

PubMed Central

Soils of coniferous forest ecosystems are important for the global carbon cycle, and the identification of active microbial decomposers is essential for understanding organic matter transformation in these ecosystems. By the independent analysis of DNA and RNA, whole communities of bacteria and fungi and its active members were compared in topsoil of a Picea abies forest during a period of organic matter decomposition. Fungi quantitatively dominate the microbial community in the litter horizon, while the organic horizon shows comparable amount of fungal and bacterial biomasses. Active microbial populations obtained by RNA analysis exhibit similar diversity as DNA-derived populations, but significantly differ in the composition of microbial taxa. Several highly active taxa, especially fungal ones, show low abundance or even absence in the DNA pool. Bacteria and especially fungi are often distinctly associated with a particular soil horizon. Fungal communities are less even than bacterial ones and show higher relative abundances of dominant species. While dominant bacterial species are distributed across the studied ecosystem, distribution of dominant fungi is often spatially restricted as they are only recovered at some locations. The sequences of cbhI gene encoding for cellobiohydrolase (exocellulase), an essential enzyme for cellulose decomposition, were compared in soil metagenome and metatranscriptome and assigned to their producers. Litter horizon exhibits higher diversity and higher proportion of expressed sequences than organic horizon. Cellulose decomposition is mediated by highly diverse fungal populations largely distinct between soil horizons. The results indicate that low-abundance species make an important contribution to decomposition processes in soils.

Baldrian, Petr; Kolarik, Miroslav; Stursova, Martina; Kopecky, Jan; Valaskova, Vendula; Vetrovsky, Tomas; Zifcakova, Lucia; Snajdr, Jaroslav; Ridl, Jakub; Vlcek, Cestmir; Voriskova, Jana

2012-01-01

175

Large diffuse halos in time-dependent space-charge potentials with colored noise  

SciTech Connect

We explore the potential impact of colored noise on space-charge-induced halo formation. By coupling particle orbits to parametric resonance, colored noise due to space-charge fluctuations and/or imperfections in the beamline can eject particles to much larger amplitudes than would be inferred from parametric resonance alone.

Courtlandt Bohn and Ioannis V. Sideris

2003-05-22

176

Troll horizontal well tests demonstrate large production potential from thin oil zones  

SciTech Connect

This paper presents the results of two long-term horizontal well tests in the Troll field. Planning and evaluation of the tests and simulation of and consequences on field development are summarized. The two tests demonstrated significant production potential from 12- to 22-m oil columns and verified the pretest assumption that one horizontal well could replace four vertical wells.

Seines, K.; Lien, S.C.; Haug, B.T. (Norsk Hydro A/S, Oslo (Norway))

1994-05-01

177

Large-scale controls on potential respiration and denitrification in riverine floodplains  

PubMed Central

Restoration measures of deteriorated river ecosystems generally aim at increasing the spatial heterogeneity and connectivity of these systems in order to increase biodiversity and ecosystem stability. While this is believed to benefit overall ecological integrity, consequences of such restoration projects on biogeochemical processes per se (i.e. ecosystem functioning) in fluvial systems are rarely considered. We address these issues by evaluating the characteristics of surface water connection between side arms and the main river channel in a former braided river section and the role and degree of connectivity (i.e. duration of surface water connection) on the sediment biogeochemistry. We hypothesized that potential respiration and denitrification would be controlled by the degree of hydrological connectivity, which was increased after floodplain restoration. We measured potential microbial respiration (SIR) and denitrification (DEA) and compared a degraded floodplain section of the Danube River with a reconnected and restored floodplain in the same river section. Re-establishing surface water connection altered the controls on sediment microbial respiration and denitrification ultimately impacting potential microbial activities. Meta-variables were created to characterize the effects of hydrology, morphology, and the available carbon and nutrient pools on potential microbial processing. Mantel statistics and path analysis were performed and demonstrate a hierarchy where the effects of hydrology on the available substrates and microbial processing are mediated by the morphology of the floodplain. In addition, these processes are highest in the least connected sites. Surface water connection, mediated by morphology regulates the potential denitrification rate and the ratio of N2O to N2 emissions, demonstrating the effects of restoration in floodplain systems.

Welti, Nina; Bondar-Kunze, Elisabeth; Singer, Gabriel; Tritthart, Michael; Zechmeister-Boltenstern, Sophie; Hein, Thomas; Pinay, Gilles

2012-01-01

178

Potential impacts of the Deepwater Horizon oil spill on large pelagic fishes  

NASA Astrophysics Data System (ADS)

Biogeographical analyses provide insights on how the Deepwater Horizon oil spill impacted large pelagic fishes. We georeferenced historical ichthyoplankton surveys and published literature to map the spawning and larval areas of bluefin tuna, swordfish, blue marlin and whale shark sightings in the Gulf of Mexico with daily satellite-derived images detecting surface oil. The oil spill covered critical areas used by large pelagic fishes. Surface oil was detected in 100% of the northernmost whale shark sightings, in 32.8 % of the bluefin tuna spawning area and 38 % of the blue marlin larval area. No surface oil was detected in the swordfish spawning and larval area. Our study likely underestimates the extend of the oil spill due to satellite sensors detecting only the upper euphotic zone and the use of dispersants altering crude oil density, but provides a previously unknown spatio-temporal analysis.

Frias-Torres, Sarrah; Bostater, Charles R., Jr.

2011-10-01

179

Sensitivity analysis of 18 different potential evapotranspiration models to observed climatic change at German climate stations  

Microsoft Academic Search

Potential evapotranspiration models very often are important part of hydrological catchment models to calculate potential\\u000a evapotranspiration (PET) which then is used to estimate actual evapotranspiration considering the soil moisture status. As\\u000a many different approaches exist, the question arises in which way the choice of the PET model affects the impact of climate\\u000a change on the calculated water balance? Therefore, 18

Helge Bormann

2011-01-01

180

Anaerobic treatability and biogas production potential studies of different agro-industrial wastewaters in Turkey  

Microsoft Academic Search

The anaerobic treatability and methane generation potential of the wastewaters of the three important agro-industries in Turkey, namely, cheese-making, poultry breeding and the olive-oil mill industries were studied. Biochemical methane potential (BMP) experiments were conducted for different initial chemical oxygen demand (COD) concentrations. The results indicate that anaerobic treatment was possible for all the wastewaters studied and the biogas produced

Göksel N. Demirer; Metin Duran; Engin Güven; Örgen Ugurlu; Ulas Tezel; Tuba H. Ergüder

2000-01-01

181

Termites: a potentially large source of atmospheric methane, carbon dioxide, and molecular hydrogen  

Microsoft Academic Search

Termites are emitting large quantities of CHâ, COâ, and Hâ into the atmosphere, especially in cleared tropical forest areas. Researchers estimate that these annual global emissions could amount to 0.3 trillion lb of CHâ, 11 trillion lb of COâ (more than twice the net global input from fossil-fuel combustion), and 0.4 trillion lb of Hâ. However, they stress that because

P. R. Zimmerman; J. P. Greenberg; S. O. Wandiga; P. J. Crutzen

1982-01-01

182

Potential of CERN large hadron collider to study high-energy-density states in matter  

Microsoft Academic Search

Numerical simulations have shown that the powerful 7TeV proton beams that will be generated at the CERN Large Hadron Collider (LHC) will be a very efficient tool to create samples of High-Energy-Density (HED) matter including strongly coupled plasmas. These plasmas are abundant in nature as they exist in starts, brown dwarfs and giant planets that makes study of such systems

N. A. Tahir; A. Shutov; I. V. Lomonosov; V. Gryaznov; A. R. Piriz; D. H. H. Hoffmann; V. E. Fortov; V. Kain; R. Schmidt

2006-01-01

183

A microsatellite linkage map of rainbow trout (Oncorhynchus mykiss) characterized by large sex-specific differences in recombination rates.  

PubMed Central

We constructed a genetic linkage map for a tetraploid derivative species, the rainbow trout (Oncorhynchus mykiss), using 191 microsatellite, 3 RAPD, 7 ESMP, and 7 allozyme markers in three backcross families. The linkage map consists of 29 linkage groups with potential arm displacements in the female map due to male-specific pseudolinkage arrangements. Synteny of duplicated microsatellite markers was used to identify and confirm some previously reported pseudolinkage arrangements based upon allozyme markers. Fifteen centromeric regions (20 chromosome arms) were identified with a half-tetrad analysis using gynogenetic diploids. Female map length is approximately 10 M, but this is a large underestimate as many genotyped segments remain unassigned at a LOD threshold of 3.0. Extreme differences in female:male map distances were observed (ratio F:M, 3.25:1). Females had much lower recombination rates (0.14:1) in telomeric regions than males, while recombination rates were much higher in females within regions proximal to the centromere (F:M, 10:1). Quadrivalent formations that appear almost exclusively in males are postulated to account for the observed differences.

Sakamoto, T; Danzmann, R G; Gharbi, K; Howard, P; Ozaki, A; Khoo, S K; Woram, R A; Okamoto, N; Ferguson, M M; Holm, L E; Guyomard, R; Hoyheim, B

2000-01-01

184

Commercial processed food may have endocrine-disrupting potential: soy-based ingredients making the difference.  

PubMed

Processed and packaged food items as well as ready-to-eat snacks are neglected and poorly characterised sources of human exposure to endocrine-disrupting chemicals (EDCs). In this study we investigated the presence of xenoestrogens in commercially processed and packaged Finnish foods, arising from substances deliberately added or inadvertently contaminating the food, substances formed as a result of food processing, or substances leaching from food packaging materials. Samples were obtained in three separate batches of equivalent products from both a supermarket and a local representative of a global chain of hamburger restaurants and extracted by a solid-phase extraction method. Their endocrine-disrupting potential was determined by yeast bioluminescent assay, using two recombinant yeast strains Saccharomyces cerevisiae BMAEREluc/ER? and S. cerevisiae BMA64/luc. In this test system, the majority of samples (both foodstuffs and wrappers) analysed proved negative. However, all batches of industrially prepared hamburgers (but not those obtained from a hamburger restaurant) as well as pepper salami significantly induced luciferase activity in the BMAEREluc/ER? yeast strain indicating the presence of xenoestrogens, with estradiol equivalents of these products ranging from 0.2 to 443 pg g(-1). All three products contained soy-based ingredients, which apparently accounted for, or at least contributed to, their high estrogenic activity, since no signal in the assay was observed with extracts of the packaging material, while two different soy sauces tested yielded an intense signal (28 and 54 pg ml(-1) estradiol-equivalent). These findings imply that by and large chemicals arising in the processing or packaging of foodstuffs in Finland constitute an insignificant source of xenoestrogens to consumers. However, soy-derived ingredients in certain food items might render the entire products highly estrogenic. The estrogenic activity of soy is attributed to isoflavones whose health effects - though widely considered beneficial - are controversial. As hamburgers are a popular type of food among children, the findings are noteworthy and possibly of concern. PMID:23886479

Omoruyi, Iyekhoetin Matthew; Kabiersch, Grit; Pohjanvirta, Raimo

2013-07-26

185

The Effective Group Potential, a New Method for the Study of Spectrum in Large Molecules: Tests and Perspectives  

SciTech Connect

The new method, called effective group potential, which generalizes the concept of effective core potential by including in a potential the effects of many atoms ligand, is used to calculate transition energies. Three molecules containing a metal atom (Cu, Cr, Ni) surrounded by NH3 ligands have been studied. It is shown that by replacing the NH3 group by an effective group potential, the characteristic transitions energies are very well reproduced at various ab initio levels. The transitions studied are transitions between open shells on the metallic center but also ligand to metal transitions where, though unexpected, quite reliable results were also obtained. This method is thus very well suited for the study of the spectrum of a large molecule under the condition that a separation between an active part plus some spectator groups can be made, a condition satisfied in most organometallic molecules as well as in biological molecules.

Heully, Jean-Louis; Poteau, Romuald; Berasaluce, Sandra; Alary, Fabienne

2002-03-22

186

Differential effects of muscimol upon the firing frequency of large and small amplitude antidromic dorsal root action potentials in rat spinal cord in vitro.  

PubMed

The effects of bath applied muscimol upon spontaneous and evoked antidromic activity recorded from lumbar dorsal roots was investigated in hemisected, isolated preparations of rat spinal cord. In magnesium free medium containing 0.1 microM 4-aminopyridine, bursts of high amplitude (up to 1 mV), dorsal root reflexes were recorded. These were blocked by low concentrations of muscimol (2-5 microM). Higher concentrations (5-20 microM) of muscimol caused a concentration-dependent increase in the frequency of small amplitude (<200 microV) spontaneous dorsal root action potentials. The possibility that the large and small amplitude extracellular action potentials reflect activity in large and small diameter dorsal root axons, and that these respond in different ways to the GABA(A) agonist muscimol, is discussed. PMID:12231431

Bagust, J; Willis, W D

2002-09-20

187

Does One Soros Make a Difference? A Theory of Currency Crises with Large and Small Traders  

Microsoft Academic Search

Do large investors increase the vulnerability of a country to speculative attacks in the foreign exchange markets? To address this issue, we build a model of currency crises where a single large investor and a continuum of small investors independently decide whether to attack a currency based on their private information about fundamentals. Even abstracting from signalling, the presence of

Giancarlo Corsetti; Amil Dasgupta; Stephen Morris; Hyun Song Shin

2004-01-01

188

Large-scale copy number variants (CNVs) detected in different ethnic human populations  

Microsoft Academic Search

The large-scale copy-number variations (CNVs) in the human genome are associated with developmental disorders and susceptibility to diseases. More importantly, CNVs may represent a major genetic component of our phenotypic diversity. Following the development of methodologies and introduction of new research platforms, accumulation of the nature and pattern of CNVs from normal populations has progressed. The examination of relatively large

N. Takahashi; Y. Satoh; M. Kodaira; H. Katayama

2008-01-01

189

Global distribution of large submarine canyons: Geomorphic differences between active and passive continental margins  

Microsoft Academic Search

The aim of this study is to assess the global occurrence of large submarine canyons to provide context and guidance for discussions regarding canyon occurrence, distribution, geological and oceanographic significance and conservation. Based on an analysis of the ETOPO1 data set, this study has compiled the first inventory of 5849 separate large submarine canyons in the world ocean. Active continental

Peter T. Harris; Tanya Whiteway

2011-01-01

190

Cytokeratin positivity in anaplastic large cell lymphoma: a potential diagnostic pitfall in misdiagnosis of metastatic carcinoma  

PubMed Central

Cytokeratin (pan) and epithelial membrane antigen (EMA) were considered as commonly useful epithelial markers to distinguish cancer from lymphoma, but the expression of cytokeratin (pan) and EMA had also been seen in some lymphomas. Here, we presented an unusual case of anaplastic large cell lymphoma (ALCL) absence of some lymphoid markers (Including CD3, CD20, Pax-5, CD45Ro) and positive for cytokeratin (pan) and EMA, which was misdiagnosed as metastatic carcinoma. Our case suggested that the epithelial markers (including cytokeratin and EMA) show an overlap with that of ALCL, which represented a diagnostic pitfall for confusing ALCL with metastatic carcinoma.

Zhang, Qingfu; Ming, Jian; Zhang, Siyang; Li, Bo; Han, Xue; Qiu, Xueshan

2013-01-01

191

Measurement of nasal potential difference in adult cystic fibrosis, Young's syndrome, and bronchiectasis.  

PubMed Central

Previous work confirmed the abnormal potential difference between the undersurface of the inferior nasal turbinate and a reference electrode in cystic fibrosis, but the technique is difficult and the results show overlap between the cystic fibrosis and the control populations. In the present study the potential difference from the floor of the nose has therefore been assessed in normal subjects, as well as in adult patients with cystic fibrosis, bronchiectasis and Young's syndrome. Voltages existing along the floor of the nasal cavity were recorded. The mean potential difference was similar in controls (-18 (SD 5) mv) and in patients with bronchiectasis (-17 (6) mv) and Young's syndrome (-20 (6) mv). The potential difference in cystic fibrosis (-45 (8) mv) was significantly different from controls (p less than 0.002) and there was no overlap between the cystic fibrosis values and values obtained in normal and diseased controls. This simple technique therefore discriminates well between patients with cystic fibrosis and other populations, raising the possibility of its use to assist in diagnosis.

Alton, E W; Hay, J G; Munro, C; Geddes, D M

1987-01-01

192

A large-cavity zeolite with wide pore windows and potential as an oil refining catalyst.  

PubMed

Crude oil is an important feedstock for the petrochemical industry and the dominant energy source driving the world economy, but known oil reserves will cover demand for no more than 50 years at the current rate of consumption. This situation calls for more efficient strategies for converting crude oil into fuel and petrochemical products. At present, more than 40% of oil conversion is achieved using catalysts based on faujasite; this zeolite requires extensive post-synthesis treatment to produce an ultrastable form, and has a large cavity accessible through four 0.74-nm-wide windows and thus limits the access of oil molecules to the catalytically active sites. The use of zeolites with better accessibility to their active sites should result in improved catalyst efficiency. To date, two zeolites with effective pore diameters exceeding that of faujasite have been reported, but their one-dimensional pore topology excludes use in oil refining. Similarly, zeolites with large pores and a three-dimensional pore topology have been reported, but in all these materials the pore openings are smaller than in faujasite. Here we report the synthesis of ITQ-21, a zeolite with a three-dimensional pore network containing 1.18-nm-wide cavities, each of which is accessible through six circular and 0.74-nm-wide windows. As expected for a zeolite with this structure, ITQ-21 exhibits high catalytic activity and selectivity for valuable products in preliminary oil refining tests. PMID:12152074

Corma, Avelino; Díaz-Cabañas, María J; Martínez-Triguero, Joaquín; Rey, Fernando; Rius, Jordi

2002-08-01

193

NREL Confirms Large Potential for Grid Integration of Wind, Solar Power (Fact Sheet)  

SciTech Connect

To fully harvest the nation's bountiful wind and solar resources, it is critical to know how much electrical power from these renewable resources could be integrated reliably into the grid. To inform the discussion about the potential of such variable sources, the National Renewable Energy Laboratory (NREL) launched two key regional studies, examining the east and west sections of the U.S. power grid. The studies show that it is technically possible for U.S. power systems to integrate 20%-35% renewable electricity if infrastructure and operational improvements can be made.

Not Available

2011-10-01

194

Analysis of Problem of High Power Fiber Laser Combining for Arbitrary Large Optical Phase Differences  

NASA Astrophysics Data System (ADS)

Coherent laser beam combining is potentially attractive way to increase the combined beam brightness beyond the limits imposed on single-mode lasers by technological bounds. The active control of every individual laser beam characteristics is more flexible but essentially more complicated in both, necessary equipment and service. Passive phase locking is an attractive alternative, since it does not need external management and leads to strong simplification of the system. A specific feature of fiber amplifiers and lasers is that they possess optical path differences (OPD) of many wavelengths magnitude. Cold-cavity theory predicts in this case fast decline in efficiency of coherent fiber laser beam combining with number of lasers. Experiments, in contrast, demonstrated in such systems that high degree of phasing takes place for laser arrays of up to 16 lasers. As lasers are strong non-linear systems, explanation of this discrepancy should rely on a role of non-linear effects: gain saturation and intensity-dependent index. Besides, since the gain band width is significantly broader than the distance between spectral lines responding to different longitudinal modes, it is a freedom in adjusting laser wavelength to a value, which corresponds to a best balance between gain and loss of laser radiation. As a first step, we consider a fiber laser array with external global coupling, which means that the same fraction of the combined laser beam is returned into the each element of the array. In this case, every laser in the array is operated as an injection controlled (slave) laser. The specific features of Yb-doped fiber lasers were taken into account in our model: 1) existence of multiple longitudinal modes; 2) typically low-Q cavity used in these lasers. This approach allows us to quantify the mechanism of laser wavelength self-adjustment taking into account the effect of gain saturation. Taking the injection signal intensity within limits of locking range, the output signal was studied as a function of wavelength detuning and small signal gain magnitude. Then the maximal phase locking efficiency is found numerically as a function of coupling strength and of optical pumping intensity at random values of the OPD for laser arrays of variable size. Just the gain saturation effect taken into account in our model leads to comparatively slow reduction of the maximal phase locking efficiency with the laser array size.

Napartovich, A. P.; Elkin, N. N.; Vysotsky, D. V.

2010-10-01

195

Energetic recoils in UO{sub 2} simulated using five different potentials  

SciTech Connect

This report presents the results of classical molecular dynamics simulations of the diffuse premelting transition, melting, and defect production by 1 keV U recoils in UO{sub 2} using five different rigid ion potentials. The experimentally observed premelting transition occurred for all five cases. For all the potentials studied, dynamic defect annealing is highly effective and is accompanied by replacement events on the anion sublattice. The primary damage state after {approx}15 ps consists of isolated Frenkel pairs and interstitial and vacancy clusters of various sizes. The average displacement energy varies from {approx}28 to {approx}83 eV and the number of Frenkel pairs is different by a factor of 3 depending on the choice of potential. The size and spatial distribution of vacancy and interstitial clusters is drastically different for the potentials studied. The results provide statistics of defect production. They point to a pressing need to determine defect formation, migration, and binding energies in UO{sub 2} from first principles and to develop reliable potentials based on this data for simulating microstructural evolution in nuclear fuel under operating conditions.

Devanathan, Ram; Yu Jianguo; Weber, William J. [Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, MS K8-87, Richland, Washington 99352 (United States)

2009-05-07

196

Epigenetic Signatures Associated with Different Levels of Differentiation Potential in Human Stem Cells  

Microsoft Academic Search

BackgroundThe therapeutic use of multipotent stem cells depends on their differentiation potential, which has been shown to be variable for different populations. These differences are likely to be the result of key changes in their epigenetic profiles.Methodology\\/Principal Findingsto address this issue, we have investigated the levels of epigenetic regulation in well characterized populations of pluripotent embryonic stem cells (ESC) and

Pablo Aranda; Xabier Agirre; Esteban Ballestar; Enrique J. Andreu; José Román-Gómez; Inés Prieto; José Ignacio Martín-Subero; Juan Cruz Cigudosa; Reiner Siebert; Manel Esteller; Felipe Prosper

2009-01-01

197

Estimating Demand Response Market Potential Among Large Commercialand Industrial Customers:A Scoping Study  

SciTech Connect

Demand response is increasingly recognized as an essentialingredient to well functioning electricity markets. This growingconsensus was formalized in the Energy Policy Act of 2005 (EPACT), whichestablished demand response as an official policy of the U.S. government,and directed states (and their electric utilities) to considerimplementing demand response, with a particular focus on "price-based"mechanisms. The resulting deliberations, along with a variety of stateand regional demand response initiatives, are raising important policyquestions: for example, How much demand response is enough? How much isavailable? From what sources? At what cost? The purpose of this scopingstudy is to examine analytical techniques and data sources to supportdemand response market assessments that can, in turn, answer the secondand third of these questions. We focus on demand response for large(>350 kW), commercial and industrial (C&I) customers, althoughmany of the concepts could equally be applied to similar programs andtariffs for small commercial and residential customers.

Goldman, Charles; Hopper, Nicole; Bharvirkar, Ranjit; Neenan,Bernie; Cappers, Peter

2007-01-01

198

Potential impacts of precipitation change on large-scale patterns of tree diversity  

NASA Astrophysics Data System (ADS)

Forests are globally important ecosystems host to outstanding biological diversity. Widespread efforts have addressed the impacts of climate change on biodiversity in these ecosystems. We show that a metacommunity model founded on basic ecological processes offers direct linkage from large-scale forcing, such as precipitation, to tree diversity patterns of the Mississippi-Missouri River System and its subregions. We quantify changes in tree diversity patterns under various projected precipitation patterns, resulting in a range of responses. Uncertainties accompanying global climate models necessitate the use of scenarios of biodiversity. Here we present results from scenarios with the largest losses and gains in tree diversity. Our results suggest that species losses under scenarios with the most dramatic contractions tend to be greater in magnitude, spatial extent, and statistical significance than gains under alternative scenarios. These findings are expected to have important implications for conservation policy and resource management.

Konar, M.; Muneepeerakul, R.; Azaele, S.; Bertuzzo, E.; Rinaldo, A.; Rodriguez-Iturbe, I.

2010-11-01

199

Termites: a potentially large source of atmospheric methane, carbon dioxide, and molecular hydrogen  

SciTech Connect

Termites are emitting large quantities of CH/sub 4/, CO/sub 2/, and H/sub 2/ into the atmosphere, especially in cleared tropical forest areas. Researchers estimate that these annual global emissions could amount to 0.3 trillion lb of CH/sub 4/, 11 trillion lb of CO/sub 2/ (more than twice the net global input from fossil-fuel combustion), and 0.4 trillion lb of H/sub 2/. However, they stress that because of many uncertainties, the acutal production of these gases could vary by a factor of two; i.e., methane production could range from 0.2 to 0.7 trillion lb. Occurring on about two-thirds of the earth's

Zimmerman, P.R.; Greenberg, J.P.; Wandiga, S.O.; Crutzen, P.J.

1982-11-01

200

Potential Impacts of Precipitation Change on Large-Scale Patterns of Tree Diversity  

NASA Astrophysics Data System (ADS)

Forests are globally important ecosystems host to outstanding biological diversity. Widespread efforts have addressed the impacts of climate change on biodiversity in these ecosystems. We show that a metacommunity model founded on basic ecological processes offers direct linkage from large-scale forcing, such as precipitation, to tree diversity patterns of the Mississippi-Missouri River System and its sub-regions. We quantify changes in tree diversity patterns under various projected precipitation patterns, resulting in a range of responses. Uncertainties accompanying global climate models necessitate the use of scenarios of biodiversity. Here, we present results from scenarios with the largest losses and gains in tree diversity. Our results suggest that species losses under scenarios with the most dramatic contractions tend to be greater in magnitude, spatial extent, and statistical significance than gains under alternative scenarios. These findings are expected to have important implications for conservation policy and resource management.

Konar, M.; Muneepeerakul, R.; Azaele, S.; Bertuzzo, E.; Rinaldo, A.; Rodriguez-Iturbe, I.

2010-12-01

201

Comparison of methane production potential, biodegradability, and kinetics of different organic substrates.  

PubMed

The methane production potential, biodegradability, and kinetics of a wide range of organic substrates were determined using a unified and simple method. Results showed that feedstocks that contained high energy density and easily degradable substrates exhibited high methane production potential and biodegradability. Lignocellulosic biomass with high content of fibrous compositions had low methane yield and biodegradability. Feedstocks with high lignin content (?15%, on a TS basis) had low first-order rate constant (0.05-0.06 1/d) compared to others. A negative linear correlation between lignin content and experimental methane yield (or biodegradability) was found for lignocellulosic and manure wastes. This could be used as a fast method to predict the methane production potential and biodegradability of fiber-rich substrates. The findings of this study provided a database for the conversion efficiency of different organic substrates and might be useful for applications of biomethane potential assay and anaerobic digestion in the future. PMID:24140354

Li, Yeqing; Zhang, Ruihong; Liu, Guangqing; Chen, Chang; He, Yanfeng; Liu, Xiaoying

2013-10-02

202

Detection and Reduction of Precipitation Effects in Geoelectrical Potential Difference Data  

NASA Astrophysics Data System (ADS)

Geoelectrical fluctuations are the end product of several geophysical phenomena. In particular geoelectrical signals measured in seismically active areas can be attributed to stress and strain changes, associated with earthquakes. In order to study the geoelectrical potential difference changes associated with the earth's crustal activities, it is important to discriminate from other noises because they are generally weak. The complexity of this problem has suggested the development of advanced statistical methods to investigate the heterogeneous nature of these fluctuations. In this paper we analyzed the time dynamics of short-term variability of geoelectrical field measured at Kiyosumi station, located in southern part of Boso peninsula, Japan. We tried to apply principal component analysis (PCA) and singular spectral analysis (SSA) to detect and reduce precipitation effects which are the most intense noise in geoelectrical potential difference data. The results show an application of PCA to two orthogonal electric data can detect the precipitation and SSA has a potential to remove the precipitation effects.

Saito, Shota; Hattori, Katsumi; Kaida, Daishi; Yoshino, Chie; Han, Peng; Febriani, Febty

203

Comparative transforming potential of different human papillomaviruses associated with non-melanoma skin cancer  

SciTech Connect

It is well established that high-risk human papillomaviruses (HPVs) that infect mucosal epithelia are the causative agents of cervical cancer. In contrast, the association of cutaneo-tropic HPV types with the development of non-melanoma skin cancer (NMSC) is less well defined. In this study, we have analysed the in vitro transforming potential of various cutaneous HPV types. Using oncogene cooperation assays with activated ras, we have shown that diverse cutaneous types, including 12, 14, 15, 24, 36 and 49, have significant transforming potential. Interestingly, most of this activity appears to be encoded by the E6 gene product. In contrast, the common HPV-10 exhibits no significant transforming potential in these assays. This difference may be a reflection of different patterns of cellular localization, with transforming E6s being nuclear and non-transforming being cytoplasmic. These results provide molecular support for a role of these viruses in the development of certain human malignancies.

Massimi, Paola; Thomas, Miranda [International Centre for Genetic Engineering and Biotechnology, Padriciano 99, I-34012 Trieste (Italy); Bouvard, Veronique [Infections and Cancer Biology Group, International Agency for Research on Cancer - World Health Organization, 150 Cours Albert Thomas, 69372 Lyon (France); Ruberto, Irene [International Centre for Genetic Engineering and Biotechnology, Padriciano 99, I-34012 Trieste (Italy); Campo, M. Saveria [Division of Pathological Sciences, Institute of Comparative Medicine, University of Glasgow, Garscube Estate, Glasgow G61 1QH (United Kingdom); Tommasino, Massimo [Infections and Cancer Biology Group, International Agency for Research on Cancer - World Health Organization, 150 Cours Albert Thomas, 69372 Lyon (France); Banks, Lawrence [International Centre for Genetic Engineering and Biotechnology, Padriciano 99, I-34012 Trieste (Italy)], E-mail: banks@icgeb.org

2008-02-20

204

Interpretation of fluctuation of transmural potential difference across the proximal small intestine  

PubMed Central

The duodenal transmural potential difference (pd) has been studied in isolated vascular-perfused preparations of canine stomach and duodenum. There was no quantitative correlation between the magnitude of the intraluminal pressure change and pd but fluctuations of pd in these preparations were related to duodenal slow wave activity.

Wingate, David; Green, Roger; Symes, John; Pilot, Marianne

1974-01-01

205

The measurement of regular and irregular surface cracks using the alternating current potential difference technique  

Microsoft Academic Search

The alternating current (AC) potential difference technique for measuring the growth of regular and irregular surface cracks is described. This technique is based on injecting high frequency alternating current into the metal specimen and measuring the change in voltage on the surface produced by the presence of a crack. The high frequency current tends to flow in a thin layer

1995-01-01

206

A modified technique for measurement of nasal transepithelial potential difference in infants  

Microsoft Academic Search

Objective: To establish a method for measuring nasal transepithelial potential difference (PD) in infants. Study design: A modified infant method (smaller catheter size, reduced flow rates, and shorter protocol time) was compared with an established adult nasal PD method in 10 adult volunteers (4 with cystic fibrosis [CF]). Nasal PD was measured in 13 infants with a possible diagnosis of

Peadar G. Noone; Darin G. Bosworth; Vicky A. LeGrys; Michael R. Knowles; Pierre M. Barker

2001-01-01

207

How to Help Children with Learning Differences Reach Their Full Potential  

ERIC Educational Resources Information Center

|This article is the third part of a 10-part series that explores Attention Deficit Hyperactivity Disorder (ADHD). It offers and discusses tips on how to help children with learning differences reach their full potential. These include: (1) start with good nutrition; (2) be sure your child is exercising; (3) make sure your child is getting enough…

Lavoie, Theresa

2008-01-01

208

Transglucosylation potential of six sucrose phosphorylases toward different classes of acceptors  

Microsoft Academic Search

In this study, the transglucosylation potential of six sucrose phosphorylase (SP) enzymes has been compared using eighty putative acceptors from different structural classes. To increase the solubility of hydrophobic acceptors, the addition of various co-solvents was first evaluated. All enzymes were found to retain at least 50% of their activity in 25% dimethylsulfoxide, with the enzymes from Bifidobacterium adolescentis and

Dirk Aerts; Tom F. Verhaeghe; Bart I. Roman; Christian V. Stevens; Tom Desmet; Wim Soetaert

2011-01-01

209

Large-scale profiling and identification of potential regulatory mechanisms for allelic gene expression in colorectal cancer cells.  

PubMed

Allelic variation in gene expression is common in humans and this variation is associated with phenotypic variation. In this study, we employed high-density single nucleotide polymorphism (SNP) chips containing 13,900 exonic SNPs to identify genes with allelic gene expression in cells from colorectal cancer cell lines. We found 2 monoallelically expressed genes (ERAP2 and MYLK4), 32 genes with an allelic imbalance in their expression, and 13 genes showing allele substitution by RNA editing. Among a total of 34 allelically expressed genes in colorectal cancer cells, 15 genes (44.1%) were associated with cis-acting eQTL, indicating that large portions of allelically expressed genes are regulated by cis-acting mechanisms of gene expression. In addition, potential regulatory variants present in the proximal promoter regions of genes showing either monoallelic expression or allelic imbalance were not tightly linked with coding SNPs, which were detected with allelic gene expression. These results suggest that multiple rare variants could be involved in the cis-acting regulatory mechanism of allelic gene expression. In the comparison with allelic gene expression data from Centre d'Etude du Polymorphisme Humain (CEPH) family B cells, 12 genes showed B-cell specific allelic imbalance and 1 noncoding SNP showed colorectal cancer cell-specific allelic imbalance. In addition, different patterns of allele substitution were observed between B cells and colorectal cancer cells. Overall, our study not only indicates that allelic gene expression is common in colorectal cancer cells, but our study also provides a better understanding of allele-specific gene expression in colorectal cancer cells. PMID:23064046

Lee, Robin Dong-Woo; Song, Min-Young; Lee, Jong-Keuk

2012-10-10

210

Nonuniform radio-frequency plasma potential due to edge asymmetry in large-area radio-frequency reactors  

SciTech Connect

In small area capacitive reactors, the rf and dc components of the plasma potential can be assumed to be uniform over all the plasma bulk because of the low plasma resistivity. In large area reactors, however, the rf plasma potential can vary over a long range across the reactor due to rf current flow and the nonzero plasma impedance. A perturbation in rf plasma potential, due to electrode edge asymmetry or the boundary of a dielectric substrate, propagates along the resistive plasma between capacitive sheaths. This is analogous to propagation along a lossy conductor in a transmission line and the damping length of the perturbation can be determined by the telegraph equation. Some consequences are the following: (i) The spatial variation in sheath rf amplitudes causes nonuniform rf power dissipation near to the reactor sidewalls. (ii) The surface charge and potential of a dielectric substrate can be negative and not only positive as for a uniform rf plasma potential. The variation of sheath dc potential across a dielectric substrate causes nonuniform ion energy bombardment. (iii) The self-bias voltage depends on the plasma parameters and on the reactor and substrate dimensions - not only on the ratio of electrode areas. (iv) The nonuniform rf plasma potential in presence of the uniform dc plasma potential leads to nonambipolar dc currents circulating along conducting surfaces and returning via the plasma. Electron current peaks can arise locally at the edge of electrodes and dielectric substrates. Perturbations to the plasma potential and currents due to the edge asymmetry of the electrodes are demonstrated by means of an analytical model and numerical simulations.

Howling, A.A.; Sansonnens, L.; Ballutaud, J.; Hollenstein, Ch.; Schmitt, J.P.M. [Centre de Recherches en Physique des Plasmas Ecole Polytechnique Federale de Lausanne, PPH-Ecublens, CH-1015 Lausanne (Switzerland); Unaxis Displays, 5 Rue Leon Blum, F-91120 Palaiseau (France)

2004-11-15

211

Spectroscopic study of the ?-potential of the system Li3D+He at large separations  

NASA Astrophysics Data System (ADS)

We have studied the Li3D+He interaction in the ? molecular state by measurements of the absorption line wing profiles of the upper Li transition 2 P 3 D, ? 610 nm. Measurements of absolute cross sections normalized to the integrated line absorption have been performed in a two step laser pump and probe scheme in the detuning range ±300 cm-1 to both sides of the line center. The analysis of the blue wing on the basis of the quantummechanical theory of the collisional line broadening shows, that the experimental 3 D? potential energy curve is less repulsive in the asymptotic range R?15 20 a.u. than predicted from semiempirical model calculations of Pascale.

Behmenburg, W.; Makonnen, A.; Findeisen, M.

1993-12-01

212

A tale of two skyrmions: The nucleon's strange quark content in different large N limits  

NASA Astrophysics Data System (ADS)

The nucleon's strange quark content comes from closed quark loops, and hence should vanish at leading order in the traditional large N (TLNC) limit. Quark loops are not suppressed in the recently proposed orientifold large N (OLNC) limit, and thus the strange quark content should be non-vanishing at leading order. The Skyrme model is supposed to encode the large N behavior of baryons, and can be formulated for both of these large N limits. There is an apparent paradox associated with the large N behavior of strange quark matrix elements in the Skyrme model. The model only distinguishes between the two large N limits via the N scaling of the couplings and the Witten Wess Zumino term, so that a vanishing leading order strange matrix element in the TLNC limit implies that it also vanishes at leading order in the OLNC limit, contrary to the expectations based on the suppression/non-suppression of quark loops. The resolution of this paradox is that the Skyrme model does not include the most general type of meson meson interaction and, in fact, contains no meson meson interactions which vanish for the TLNC limit but not the OLNC. The inclusion of such terms in the model yields the expected scaling for strange quark matrix elements.

Cherman, Aleksey; Cohen, Thomas D.

2006-10-01

213

Radial velocities for different spectral lines of B and A supergiants in our Galaxy and in the Large Magellanic Cloud  

Microsoft Academic Search

Coudé spectra of 23 early-type supergiants (16 of them belong to our Galaxy and 7 to the Large Magellanic Cloud (LMC)) were measured to study the radial velocities of all metallic and non-metallic lines in relation to their EP + IP (high excitation + ionization potential). The identified elements of the spectra do not show any systematic dependence (gradient) of

E. Kontizas; M. Kontizas

1981-01-01

214

Plasma Simulation Using the Streamlined DARWIN Field Model with Applications to the Generation of Large Transient Potentials Within Anisotropic Plasmas.  

NASA Astrophysics Data System (ADS)

BEAGLE/GYMNOS, a two and one-half dimensional r-z particle-in-cell plasma simulation code using the Darwin limit of Maxwell's equations, is applied to the generation and control of transient potentials within anisotropic plasmas. The Darwin limit neglects the part of the displacement current which generates electromagnetic waves. Previous implementations of the Darwin model suffered from ambiguous boundary conditions needed in the vector decomposition of plasma source terms for the field equations. Use of the streamlined Darwin field model obviates the need for these troublesome vector decompositions, but results in a set of coupled partial differential equations. Applying the dynamic alternating-direction implicit (DADI) method to the coupled set of equations yields a fast and efficient field solution. Analysis of the DADI method as applied to coupled PDE's is presented, along with a comparison between DADI and the biconjugate gradient method. The code is applied to the generation and control of large electric potentials within mirror-confined plasmas. Suddenly applying a magnetic field at the midpoint of a mirror cell containing a low-density, high electron temperature plasma generates large potentials due to charge separation as the electrons respond to the mirror force. The resulting potential contours may prove useful for accelerating beams of heavy ions for inertial fusion applications. The results of simulations are presented and compared with those of analytic theory.

Larson, David Jeffrey

215

Potential fluctuation associated with the energetic-particle-induced geodesic acoustic mode in the Large Helical Device  

NASA Astrophysics Data System (ADS)

Geodesic acoustic modes (GAM) driven by energetic particles are observed in the Large Helical Device (LHD) by a heavy ion beam probe. The GAM localizes near the magnetic axis. It is confirmed that the energetic-particle-induced GAM is accompanied by an electrostatic potential fluctuation and radial electric field fluctuation. The amplitude of the potential fluctuation is several hundred volts, and it is much larger than the potential fluctuation associated with turbulence-induced GAMs observed in the edge region in tokamak plasmas. The energetic-particle-induced GAM modulates the amplitude of the density fluctuation in a high-frequency range. The observed GAM frequency is constant at the predicted GAM frequency in plasmas with reversed magnetic shear. On the other hand, it shifts upwards from the predicted GAM frequency in plasmas with monotonic magnetic shear.

Ido, T.; Shimizu, A.; Nishiura, M.; Nakamura, S.; Kato, S.; Nakano, H.; Yoshimura, Y.; Toi, K.; Ida, K.; Yoshinuma, M.; Satake, S.; Watanabe, F.; Morita, S.; Goto, M.; Itoh, K.; Kubo, S.; Shimozuma, T.; Igami, H.; Takahashi, H.; Yamada, I.; Narihara, K.; LHD Experiment Group

2011-07-01

216

Anaplastic large cell lymphoma: a potential pitfall in the differential diagnosis of melanoma.  

PubMed

The diagnosis of metastatic melanoma can be complicated by absent characteristic cytology, melanin, or antigen expression in a suspect tumor, putting the pathologist at risk for incorrectly diagnosing recurrent melanoma while missing a second malignancy. We report a 69-year-old man with a history of acral melanoma, metastatic to inguinal nodes, presenting with an ipsilateral thigh nodule. Histology showed a proliferation of pleomorphic cells in the dermis and subcutis, suspicious for melanoma. S100, Melan-A, and HMB-45 immunohistochemistry were negative. However, microphthalmia-associated transcription factor and CD117 labeled the neoplasm, prompting consideration of a late metastatic melanoma with loss of antigen expression. Subsequent immunolabeling for CD4, CD43, and CD30 and clonal T-cell gene rearrangements enabled the correct diagnosis of cutaneous anaplastic large cell lymphoma. This case illustrates a pitfall in evaluating tumors in patients with known metastatic melanoma, and emphasizes the need for broad-spectrum immunohistochemistry in cases that are not clear-cut. PMID:23368872

Pulitzer, Melissa; Brady, Mary Sue; Blochin, Elen; Amin, Bijal; Teruya-Feldstein, Julie

2013-02-01

217

Potentiation of large conductance KCa channels by niflumic, flufenamic, and mefenamic acids.  

PubMed Central

Large conductance calcium-activated K+ (KCa) channels are rapidly activated by niflumic acid dose-dependently and reversibly. External niflumic acid was about 5 times more potent than internal niflumic acid, and its action was characterized by an increase in the channel affinity for [Ca2+], a parallel left shift of the voltage-activation curve, and a decrease of the channel long-closed states. Niflumic acid applied from the external side did not interfere with channel block by charybdotoxin, suggesting that its site of action is not at or near the charybdotoxin receptor. Accordingly, partial tetraethylammonium blockade did not interfere with channel activation by niflumic acid. Flufenamic acid and mefenamic acid also stimulated KCa channel activity and, as niflumic acid, they were more potent from the external than from the internal side. Fenamates applied from the external side displayed the following potency sequence: flufenamic acid approximately niflumic acid >> mefenamic acid. These results indicate that KCa channels possess at least one fenamatereceptor whose occupancy leads to channel opening.

Ottolia, M; Toro, L

1994-01-01

218

Potential nucleation scavenging of smoke particles over large fires: A parametric study  

SciTech Connect

During hypothesized nuclear exchanges massive fires may be ignited and inject large amounts of smoke into the atmosphere. Considerable evidence has been accumulated to suggest that nucleation scavenging where smoke particles serve as cloud condensation nuclei (CCN) may be an important mechanism for incorporating these particles into cloud water. The fraction of smoke particles that act as CCN depends on the cloud environment as well as the affinity of the smoke particles to water. A numerical model of the detailed microphysics of condensation growth on aerosol and cloud drop distributions is employed to produce a parametric study of the dependence of nucleation to a range of conditions. We consider aerosol number concentrations of 10/sup 9//m/sup 3/ to 10/sup 13//m/sup 3/, updraft speeds from 1 to 100 m/s and aerosol particles from fully water soluble to insoluble but wettable. The study provides insight into how well we must characterize smoke particles in order to predict the fraction that act as CCN given the dynamical environment.

Edwards, L.L.; Penner, J.E.

1987-08-01

219

Communalities and differences in fear potentiation between cardiac defense and eyeblink startle.  

PubMed

This study examines similarities and differences in fear potentiation between two protective reflexes: cardiac defense and eyeblink startle. Women reporting intense fear of animals but low fear of blood or intense fear of blood but low fear of animals viewed pictures depicting blood or the feared animal for 6 s in 2 separate trials in counterbalanced order. An intense burst of white noise, able to elicit both a cardiac defense response and a reflexive startle blink, was presented 3.5 s after picture onset. Both cardiac and blink responses were potentiated when highly fearful individuals viewed fearful pictures. However, differences appeared concerning picture order. This pattern of results indicates communalities and differences among protective reflexes that are relevant for understanding the dynamics of emotional reflex modulation. PMID:19572906

Sánchez, María B; Guerra, Pedro; Muñoz, Miguel A; Mata, José Luís; Bradley, Margaret M; Lang, Peter J; Vila, Jaime

2009-07-01

220

Potential Synaptic Connectivity of Different Neurons onto Pyramidal Cells in a 3D Reconstruction of the Rat Hippocampus  

PubMed Central

Most existing connectomic data and ongoing efforts focus either on individual synapses (e.g., with electron microscopy) or on regional connectivity (tract tracing). An individual pyramidal cell (PC) extends thousands of synapses over macroscopic distances (?cm). The contrasting requirements of high-resolution and large field of view make it too challenging to acquire the entire synaptic connectivity for even a single typical cortical neuron. Light microscopy can image whole neuronal arbors and resolve dendritic branches. Analyzing connectivity in terms of close spatial appositions between axons and dendrites could thus bridge the opposite scales, from synaptic level to whole systems. In the mammalian cortex, structural plasticity of spines and boutons makes these “potential synapses” functionally relevant to learning capability and memory capacity. To date, however, potential synapses have only been mapped in the surrounding of a neuron and relative to its local orientation rather than in a system-level anatomical reference. Here we overcome this limitation by estimating the potential connectivity of different neurons embedded into a detailed 3D reconstruction of the rat hippocampus. Axonal and dendritic trees were oriented with respect to hippocampal cytoarchitecture according to longitudinal and transversal curvatures. We report the potential connectivity onto PC dendrites from the axons of a dentate granule cell, three CA3 PCs, one CA2 PC, and 13 CA3b interneurons. The numbers, densities, and distributions of potential synapses were analyzed in each sub-region (e.g., CA3 vs. CA1), layer (e.g., oriens vs. radiatum), and septo-temporal location (e.g., dorsal vs. ventral). The overall ratio between the numbers of actual and potential synapses was ?0.20 for the granule and CA3 PCs. All potential connectivity patterns are strikingly dependent on the anatomical location of both pre-synaptic and post-synaptic neurons.

Ropireddy, Deepak; Ascoli, Giorgio A.

2011-01-01

221

Epigenetic Signatures Associated with Different Levels of Differentiation Potential in Human Stem Cells  

PubMed Central

Background The therapeutic use of multipotent stem cells depends on their differentiation potential, which has been shown to be variable for different populations. These differences are likely to be the result of key changes in their epigenetic profiles. Methodology/Principal Findings to address this issue, we have investigated the levels of epigenetic regulation in well characterized populations of pluripotent embryonic stem cells (ESC) and multipotent adult stem cells (ASC) at the trancriptome, methylome, histone modification and microRNA levels. Differences in gene expression profiles allowed classification of stem cells into three separate populations including ESC, multipotent adult progenitor cells (MAPC) and mesenchymal stromal cells (MSC). The analysis of the PcG repressive marks, histone modifications and gene promoter methylation of differentiation and pluripotency genes demonstrated that stem cell populations with a wider differentiation potential (ESC and MAPC) showed stronger representation of epigenetic repressive marks in differentiation genes and that this epigenetic signature was progressively lost with restriction of stem cell potential. Our analysis of microRNA established specific microRNA signatures suggesting specific microRNAs involved in regulation of pluripotent and differentiation genes. Conclusions/Significance Our study leads us to propose a model where the level of epigenetic regulation, as a combination of DNA methylation and histone modification marks, at differentiation genes defines degrees of differentiation potential from progenitor and multipotent stem cells to pluripotent stem cells.

Ballestar, Esteban; Andreu, Enrique J.; Roman-Gomez, Jose; Prieto, Ines; Martin-Subero, Jose Ignacio; Cigudosa, Juan Cruz; Siebert, Reiner; Esteller, Manel; Prosper, Felipe

2009-01-01

222

Computation of action potential propagation and presynaptic bouton activation in terminal arborizations of different geometries.  

PubMed Central

Action potential propagation in axons with bifurcations involving short collaterals with synaptic boutons has been simulated using SPICE, a general purpose electrical circuit simulation program. The large electrical load of the boutons may lead to propagation failure at otherwise uncritical geometric ratios. Because the action potential gradually fails while approaching the branch point, the electrotonic spread of the failing action potential cannot depolarize the terminal boutons above an assumed threshold of 20 mV (Vrest = 0 mV) for the presynaptic calcium inflow, and therefore fails to evoke transmitter release even for boutons attached at short collaterals. For even shorter collaterals the terminal boutons can again be activated by the spread of passive current reflected at the sealed end of the bouton which increases the membrane potential above firing threshold. The action potential is then propagated in anterograde fashion into the main axon and may activate the terminal bouton on the other collateral. Differential activation of the synaptic boutons can be observed without repetitive activation of the main axon and with the assumption of uniform membrane properties. Axon enlargements above a critical size at branch points can increase the safety factor for propagation significantly and may serve a double function: they can act both as presynaptic boutons and as boosters, facilitating invasion of the action potential into the terminal arborizations. The architecture of the terminal arborizations has a profound effect on the activation pattern of synapses, suggesting that terminal arborizations not only distribute neural information to postsynaptic cells but may also be able to process neural information presynaptically.

Luscher, H R; Shiner, J S

1990-01-01

223

Multicomponent interparticle-potential lattice Boltzmann model for fluids with large viscosity ratios  

NASA Astrophysics Data System (ADS)

This work focuses on an improved multicomponent interparticle-potential lattice Boltzmann model. The model results in viscosity-independent equilibrium densities and is capable of simulating kinematic viscosity ratios greater than 1000. External forces are incorporated into the discrete Boltzmann equation, rather than through an equilibrium velocity shift as in the original Shan and Chen (hereafter, SC) model. The model also requires the derivation of a momentum conserving effective velocity, which is substituted into the equilibrium distribution function and applies to both the single- and multiple-relaxation-time formulations. Additionally, higher-order isotropy is used in the calculation of the fluid-fluid interaction forces to reduce the magnitude of spurious currents (i.e., numerical errors) in the vicinity of interfaces. First, we compare the model to the SC model for static bubble simulations. We demonstrate that the model results in viscosity-independent equilibrium bubble densities for a wide range of kinematic viscosities, which is not the case for the SC model. Furthermore, we show that the model is capable of simulating stable bubbles for kinematic viscosity ratios greater than 1000 (when higher-order isotropy is used), whereas the SC model is known to be limited to kinematic viscosity ratios on the order of 10. Next we verify the model for surface tension via Laplace's law and show that the model results in the same surface tension values for a range of kinematic viscosities and kinematic viscosity ratios of 10, 100, and 1000. The model is also verified for layered cocurrent flow though parallel plates. We show that the simulated velocity profiles preserve continuity at the interface for kinematic viscosity ratios ranging from 0.001 to 1000 and that the model accurately predicts nonwetting and wetting phase relative permeability for kinematic viscosity ratios of 0.01 to 100.

Porter, Mark L.; Coon, E. T.; Kang, Q.; Moulton, J. D.; Carey, J. W.

2012-09-01

224

An Aspergillus chitosanase with potential for large-scale preparation of chitosan oligosaccharides.  

PubMed

A chitosan-degrading fungus, designated Aspergillus sp. Y2K, was isolated from soil. The micro-organism was used for producing chitosanase (EC 3.2.1.132) in a minimal medium containing chitosan as the sole carbon source. The induced chitosanase was purified to homogeneity from the culture filtrate by concentration and cationic SP-Sepharose chromatography. The purified enzyme is a monomer with an estimated molecular mass of 25 kDa by SDS/PAGE and of 22 kDa by gel-filtration chromatography. pI, optimum pH and optimum temperature values were 8.4, 6.5 and 65-70 degrees C, respectively. The chitosanase is stable in the pH range from 4 to 7.5 at 55 degrees C. Higher deacetylated chitosan is a better substrate. Chitin, xylan, 6-O-sulphated chitosan and O-carboxymethyl chitin were indigestible by the purified enzyme. By endo-splitting activity, the chitosanase hydrolysed chitosan to form chitosan oligomers with chitotriose, chitotetraose and chitopentaose as the major products. The enzyme hydrolyses chitohexaose to form chitotriose, while the chitopentaose and shorter oligomers remain intact. The N-terminal amino acid sequence of the enzyme was determined as YNLPNNLKQIYDDHK, which provides useful information for further gene cloning of this enzyme. A 275 g-scale hydrolysis of chitosan was performed. The product distribution was virtually identical to that of the small-scale reaction. Owing to the simple purification process and high stability of the enzyme, it is potentially valuable for industrial applications. PMID:11115392

Cheng, C Y; Li, Y K

2000-12-01

225

Vestibular-evoked myogenic potentials in three patients with large vestibular aqueduct.  

PubMed

An enlarged vestibular aqueduct (LVA) is a common congenital inner ear anomaly responsible for some unusual vestibular and audiological symptoms. Most of the cases show bilateral early onset and progressive hearing loss in children. The gross appearance on CT scan of the inner ear is generally normal. However, precise measurements of the inner ear components reveal abnormal dimensions, which may account for the accompanying auditory and vestibular dysfunction. Despite extensive studies on hearing and the vestibular apparatus, saccular function is not studied. To our knowledge this is the first report of saccular malfunction in three patients with LVA by means of vestibular evoked myogenic potentials. Conventional audiograms revealed bilateral severe sensorineural hearing loss in two patients and mixed type hearing loss in one patient. Two of the patients complained about vertigo and dizziness but vestibular assessments of the patients showed normal results. The diagnosis had been made by high-resolution CT scans and MR images of the skull that showed LVA in the absence of other anomalies. The VEMP threshold measured from the ear with LVA in two patients with unilateral enlargement of the vestibular aqueduct was 75-80 dB nHL whereas the threshold from normal ears was 95 dB nHL. The third patient with mixed type hearing loss and bilateral LVA had VEMP responses despite a big air-bone gap in the low frequency range. The VEMP in this patient was greater in amplitude and lower in threshold in the operated ear (the patient had a tympanoplasty which did not improve her hearing). These findings and results of other patients with Tullio phenomenon and superior semicircular canal dehiscence, who also showed lower VEMP threshold, confirmed the theory of a 'third window' that allows volume and pressure displacements, and thus larger deflection of the vestibular sensors, which would cause the vestibular organ to be more responsive to sound and pressure changes. PMID:15051138

Sheykholeslami, Kianoush; Schmerber, Sébastien; Habiby Kermany, Mohammad; Kaga, Kimitaka

2004-04-01

226

Differences between the nodes of Ranvier of large and small diameter fibres in the P.N.S  

Microsoft Academic Search

Summary The architecture of nodes of Ranvier in the spinal nerve roots of the rabbit has been examined. It has been shown that the nodes of large diameter fibres (mean 12 µm) are structurally different from those of small diameter fibres (mean 3 µm) on the basis of differences in the degree of axonal constriction, the frequent packing of axoplasmic

Cedric S. Raine; F. Kennedy

1982-01-01

227

Gender differences in colorectal cancer screening and incidence in large nationwide, population-based cohorts  

Microsoft Academic Search

Background. A few studies have reported gender differences along the colorectal cancer (CRC) continuum but none has done so longitudinally to compare a cancer and a non-cancer populations.^ Objectives and Methods. To examine gender differences in colorectal cancer screening (CRCS); to examine trends in gender differences in CRC screening among two groups of patients (Medicare beneficiaries with and without cancer);

Peter Nathaniel Abotchie

2010-01-01

228

Age difference in numeral recognition and calculation: an event-related potential study.  

PubMed

In this study, we investigated the age difference in numeral recognition and calculation in one group of school-aged children (n = 38) and one of undergraduate students (n = 26) using the event-related potential (ERP) methods. Consistent with previous reports, the age difference was significant in behavioral results. Both numeral recognition and calculation elicited a negativity peaking at about 170-280 ms (N2) and a positivity peaking at 200-470 ms (pSW) in raw ERPs, and a difference potential (dN3) between 360 and 450 ms. The difference between the two age groups indicated that more attention resources were devoted to arithmetical tasks in school-aged children, and that school-aged children and undergraduate students appear to use different strategies to solve arithmetical problems. The analysis of frontal negativity suggested that numeral recognition and mental calculation impose greater load on working memory and executive function in schoolchildren than in undergraduate students. The topography data determined that the parietal regions were responsible for arithmetical function in humans, and there was an age-related difference in the area of cerebral activation. PMID:17364561

Xuan, Dong; Wang, Suhong; Yang, Yilin; Meng, Ping; Xu, Feng; Yang, Wen; Sheng, Wei; Yang, Yuxia

2007-01-01

229

Antioxidative and antiinflammatory potential of different functional drink concepts in vitro.  

PubMed

The present study was undertaken to investigate the antioxidative effects of three different functional drink concepts especially designed to improve the body's performance and function and to possess high antioxidant activities. The concepts based on the mixture of various plant ingredients were: (1) eQ - equalize your nutrient balance, brain line [acerola-dragon fruit], (2) eQ - equalize your nutrient balance, beauty line [honey-pepper] and (3) Let's get red [intense]. By using a cell-based test assay, the study investigated the potential of the functional drinks to inactivate reactive superoxide anion radicals generated by inflammation-mediating cells as well as the effect on basal metabolism of these cells (antioxidant and antiinflammatory potential). In addition, by using a cell-free test assay the potential of the drinks to inactivate free exogenous superoxide anion radicals (scavenger effect) was investigated. The data presented here demonstrate the different radical scavenging, antioxidant and anti-inflammatory potential of the functional drink concepts. In particular Let's get red [intense] turned out to be the most potent drink in this respect and demonstrated marked efficacy in scavenging, antioxidant and antiinflammatory action. PMID:18979495

Dartsch, Peter C; Kler, Adolf; Kriesl, Erwin

2009-02-01

230

Phenomenon of labyrinth weal with Low static pressure difference and large clearance  

Microsoft Academic Search

Absract  The low pressure axial flow fans with an outer ring, used for cooling automobile radiators, have a significantly large tip\\u000a clearance between the ring tip and the fan shroud. It has been found that the turbulent reverse flow, or leakage flow, which\\u000a occurs at the tip clearance, greatly affects the fan performance and noise level. Therefore, in order to improve

K. Kimura; H. Ohta; K. Aoki

2003-01-01

231

Profit efficiency sources and differences among small and large U.S. commercial banks  

Microsoft Academic Search

Profit efficiency is an econometric financial performance measure of how well actual profitability compares to a best-practice\\u000a frontier. We compare the profit efficiency of small (under $100 million in total assets), medium, and large (over $1 billion)\\u000a commercial banks for the period 1995 to 2001 and examine the sources of profit efficiency for each. We also consider whether\\u000a banks of

Aigbe Akhigbe; James McNulty

2005-01-01

232

Large-scale synthesis, characterization and microwave absorption properties of carbon nanotubes of different helicities  

SciTech Connect

Carbon nanotubes of high helicity (H-HCNTs, Sample A) have been synthesized in large-scale by pyrolysis of acetylene at 450 deg. C over Fe nanoparticles derived from coprecipitation/hydrogen reduction method. With controlled introduction of hydrogen during acetylene pyrolysis, CNTs of low helicity (L-HCNTs, Sample B) and worm-like CNTs (Sample C) were obtained in large quantities. The yields of the CNTs products are high, especially that of H-HCNTs (ca. 7474%). The complex permittivity and permeability of Composites A, B, and C that contain Samples A, B and C (30 wt%) were measured in the 2-18 GHz frequency range. Good absorption of electromagnetic wave (reflection loss<-20 dB) was observed in the 7.18-10.68 and 7.5-10.7 GHz range over Composites B and C (2.0-3.0 mm thickness), respectively. Thus, through the suggested route, CNTs can be produced easily and selectively in large quantities. The lightweight materials can be utilized for microwave absorption. - Graphical abstract: FESEM image of Sample B and reflection loss versus frequency of Composite B (containing 30 wt% of Sample B) in the range of 2-18 GHz.

Qi Xiaosi; Yang Yi [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Zhong Wei, E-mail: wzhong@nju.edu.c [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Deng Yu [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Au Chaktong [Chemistry Department, Hong Kong Baptist University (Hong Kong); Du Youwei [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China)

2009-10-15

233

Performance assessment of different constraining potentials in computational structure prediction for disulfide-bridged proteins.  

PubMed

The presence of disulfide bonds in proteins has very important implications on the three-dimensional structure and folding of proteins. An adequate treatment of disulfide bonds in de-novo protein simulations is therefore very important. Here we present a computational study of a set of small disulfide-bridged proteins using an all-atom stochastic search approach and including various constraining potentials to describe the disulfide bonds. The proposed potentials can easily be implemented in any code based on all-atom force fields and employed in simulations to achieve an improved prediction of protein structure. Exploring different potential parameters and comparing the structures to those from unconstrained simulations and to experimental structures by means of a scoring function we demonstrate that the inclusion of constraining potentials improves the quality of final structures significantly. For some proteins (1KVG and 1PG1) the native conformation is visited only in simulations in presence of constraints. Overall, we found that the Morse potential has optimal performance, in particular for the ?-sheet proteins. PMID:21864792

Kondov, Ivan; Verma, Abhinav; Wenzel, Wolfgang

2011-05-27

234

Contact Potential Difference Techniques as Probing Tools in Tribology and Surface Mapping  

Microsoft Academic Search

Contact potential differences techniques have been adapted for continuous nondestructive monitoring of changes in the electron\\u000a work function of a rubbing surface. The method can be used to investigate tribological materials for a wide range of conditions,\\u000a including changes in load, sliding speed, and environment, with or without lubrication. It relies on the sensitivity of the\\u000a work function to the

Anatoly Zharin

2010-01-01

235

Effects of gadolinium ions upon rat prostatic cancer cell lines of markedly different metastatic potential  

Microsoft Academic Search

The effects of gadolinium chloride, a non-specific blocker of mechanosensitive ion channels (MSICs), upon the motility and proliferation of two Dunning rat prostatic tumour cell lines of markedly different metastatic potential were investigated. Gadolinium (2–10 ?M) caused a dose-dependent increase in the distance moved in ‘wound’ assays over a 48-h testing period. The highly metastatic MAT-LyLu cell line was significantly

Jason Verrall; Scott P Fraser; Mustafa B. A Djamgoz

1999-01-01

236

Flash visual evoked potentials at 2-year-old infants with different birth weights  

Microsoft Academic Search

Background  Increased prevalence of visual impairments has been reported in preterm populations. However, it remains unclear about the\\u000a long-term visual electrophysiological outcomes and their association with visual cognitive functions in premature infants.\\u000a We investigated visual electrophysiological outcome of 2-year-old infants of different birth weights by flash visual evoked\\u000a potentials (FVEPs) in order to explore the correlation between visual cognitive functions and

Jing-Jing Feng; Ting-Xue Wang; Chen-Hao Yang; Wei-Ping Wang; Xiu Xu

2010-01-01

237

Potentials and constraints of different types of soil moisture observations for flood simulations in headwater catchments  

Microsoft Academic Search

Flood generation in mountainous headwater catchments is governed by rainfall intensities, by the spatial distribution of rainfall\\u000a and by the state of the catchment prior to the rainfall, e.g. by the spatial pattern of the soil moisture, groundwater conditions\\u000a and possibly snow. The work presented here explores the limits and potentials of measuring soil moisture with different methods\\u000a and in

Axel Bronstert; Benjamin Creutzfeldt; Thomas Graeff; Irena Hajnsek; Maik Heistermann; Sibylle Itzerott; Thomas Jagdhuber; David Kneis; Erika Lück; Dominik Reusser; Erwin Zehe

238

Silver\\/silver chloride electrodes for measurement of potential difference in human bronchi  

Microsoft Academic Search

BACKGROUNDAn easy and reliable method to measure potential difference (PD) in the lower airways would be of interest in the field of cystic fibrosis. We have developed silver\\/silver chloride (Ag\\/AgCl) electrodes to measure PD in the lower airways.METHODSTo validate this technique the nasal PD measured with Ag\\/AgCl electrodes and with conventional perfused electrodes was compared in 16 patients. The range

Isabelle Fajac; Jacques Lacronique; Alain Lockhart; Josette Dall’Ava-Santucci; Daniel J Dusser

1998-01-01

239

Sex differences in brain maturation as measured using event-related potentials.  

PubMed

Little is known about how sex influences functional brain maturation. The current study investigated sex differences in the maturation of event-related potential (ERP) amplitudes during an auditory oddball task (N = 170; age = 6-17 years). Performance improved with age. N200 amplitude declined with age: parietal sites showed earlier development than temporal and frontal locations. Girls showed greater bilateral frontal P300 amplitude development, approaching the higher values observed in boys during childhood. After controlling for age, right frontal P300 amplitude was associated with reaction time in girls. The findings demonstrate sex differences in ERP maturation in line with behavioral and neuroimaging studies. PMID:22799761

Sumich, Alexander L; Sarkar, Sagari; Hermens, Daniel F; Ibrahimovic, Almira; Kelesidi, Katerina; Wilson, Daniel; Rubia, Katya

2012-01-01

240

Large-scale, high-resolution electrophysiological imaging of field potentials in brain slices with microelectronic multielectrode arrays  

PubMed Central

Multielectrode arrays (MEAs) are extensively used for electrophysiological studies on brain slices, but the spatial resolution and field of recording of conventional arrays are limited by the low number of electrodes available. Here, we present a large-scale array recording simultaneously from 4096 electrodes used to study propagating spontaneous and evoked network activity in acute murine cortico-hippocampal brain slices at unprecedented spatial and temporal resolution. We demonstrate that multiple chemically induced epileptiform episodes in the mouse cortex and hippocampus can be classified according to their spatio-temporal dynamics. Additionally, the large-scale and high-density features of our recording system enable the topological localization and quantification of the effects of antiepileptic drugs in local neuronal microcircuits, based on the distinct field potential propagation patterns. This novel high-resolution approach paves the way to detailed electrophysiological studies in brain circuits spanning spatial scales from single neurons up to the entire slice network.

Ferrea, E.; Maccione, A.; Medrihan, L.; Nieus, T.; Ghezzi, D.; Baldelli, P.; Benfenati, F.; Berdondini, L.

2012-01-01

241

Shock-induced plasticity in tantalum single crystals: Interatomic potentials and large-scale molecular-dynamics simulations  

NASA Astrophysics Data System (ADS)

We report on large-scale nonequilibrium molecular dynamics simulations of shock wave compression in tantalum single crystals. Two new embedded atom method interatomic potentials of Ta have been developed and optimized by fitting to experimental and density functional theory data. The potentials reproduce the isothermal equation of state of Ta up to 300 GPa. We examined the nature of the plastic deformation and elastic limits as functions of crystal orientation. Shock waves along (100), (110), and (111) exhibit elastic-plastic two-wave structures. Plastic deformation in shock compression along (110) is due primarily to the formation of twins that nucleate at the shock front. The strain-rate dependence of the flow stress is found to be orientation dependent, with (110) shocks exhibiting the weaker dependence. Premelting at a temperature much below that of thermodynamic melting at the shock front is observed in all three directions for shock pressures above about 180 GPa.

Ravelo, R.; Germann, T. C.; Guerrero, O.; An, Q.; Holian, B. L.

2013-10-01

242

Bacterial genome adaptation to niches: Divergence of the potential virulence genes in three Burkholderia species of different survival strategies  

PubMed Central

Background Two closely related species Burkholderia mallei (Bm) and Burkholderia pseudomallei (Bp) are serious human health hazards and are potential bio-warfare agents, whereas another closely related species Burkholderia thailandensis (Bt) is a non-pathogenic saprophyte. To investigate the genomic factors resulting in such a dramatic difference, we first identified the Bm genes responsive to the mouse environment, and then examined the divergence of these genes in Bp and Bt. Results The genes down-expressed, which largely encode cell growth-related proteins, are conserved well in all three species, whereas those up-expressed, which include potential virulence genes, are less well conserved or absent notably in Bt. However, a substantial number of up-expressed genes is still conserved in Bt. Bm and Bp further diverged from each other in a small number of genes resulting from unit number changes in simple sequence repeats (ssr) in the homologs. Conclusion Our data suggest that divergent evolution of a small set of genes, rather than acquisition or loss of pathogenic islands, is associated with the development of different life styles in these bacteria of similar genomic contents. Further divergence between Bm and Bp mediated by ssr changes may reflect different adaptive processes of Bm and Bp fine-tuning into their host environments.

Kim, H Stanley; Schell, Mark A; Yu, Yan; Ulrich, Ricky L; Sarria, Saul H; Nierman, William C; DeShazer, David

2005-01-01

243

Membrane potential difference and intracellular cation concentrations in human placental trophoblast cells in culture.  

PubMed Central

1. The electrochemical gradients for Na+ and K+ were assessed in a cell culture model of trophoblast differentiation. 2. Membrane potential difference (Em), intracellular water and Na+ and K+ contents were measured in choriocarcinoma cells (JAr cell line; 96% of which are undifferentiated trophoblast cells) and in mononucleate and multinucleate (differentiated) cytotrophoblast cells isolated from the human placenta at term. 3. There was a significant fall in Em from -57 mV in JAr cells, to -48 and -40 mV in mono-and multinucleate cytotrophoblast cells, respectively. Treatment with ouabain (1 mM for 15 min) depolarized the JAr cell membrane by 15 mV but did not affect cytotrophoblast cell membrane potential. 4. Intracellular K+ concentration was similar in JAr, mono- and multinucleate cytotrophoblast cells but Na+ concentration was higher in mononucleate cytotrophoblast cells compared with JAr cells. 5. Ouabain treatment (3 mM for 15 min) caused a small increase (4.5%) in cell water in mononucleate cytotrophoblast cells but lowered K+ (approximately 30%) and increased Na+ concentration (approximately 125%) in all the trophoblast cells studied. 6. The K+ equilibrium potential (EK) was more negative than Em in all cells and the difference between EK and Em was smaller in JAr cells (-25 mV) than in mono- and multinucleate cytotrophoblast cells (-33 and -43 mV, respectively). 7. The Na+ equilibrium potential (ENa) was positive in the trophoblast cells and the difference between ENa and Em was 122, 100 and 100 mV in JAr, mono- and multinucleate cytotrophoblast cells, respectively. 8. These results suggest that the electrochemical gradient for K+ is affected by the stage of trophoblast cell differentiation. In contrast, the electrochemical gradient for Na+ is similar in mono- and multinucleate cytotrophoblast cells. Images Figure 1

Greenwood, S L; Clarson, L H; Sides, M K; Sibley, C P

1996-01-01

244

Large amplitude bending motion in CsOH, studied through ab initio-based three-dimensional potential energy functions  

NASA Astrophysics Data System (ADS)

The large-amplitude bending motion in CsOH, a ‘classical’ molecule whose microwave spectrum was first recorded in 1967, has been studied ab initio. The three-dimensional potential energy surface has been calculated at the RCCSD(T)_DK3/[QZP + g ANO-RCC (Cs, O, H)] level of theory and employed in MORBID calculations of the rotation-vibration energies and intensities. The ground electronic state is 1Cs(OH)?. Hence, the bending potential is shallow and gives rise to large-amplitude bending motion. The ro-vibrationally averaged structural parameters, determined as expectation values over MORBID wavefunctions, are 0 = 2.3987 Å, 0 = 0.9754 Å, and 0 = 163°. Although the averaged structure in the vibrational ground state is far from being linear, the Yamada-Winnewissi-linearity parameter for CsOH is ?0?-1.0, the value characteristic for a linear molecule.

Hirano, Tsuneo; Derpmann, Valerie; Nagashima, Umpei; Jensen, Per

2010-10-01

245

Monitoring for potential adverse effects of prenatal gene therapy: use of large animal models with relevance to human application.  

PubMed

Safety is an absolute prerequisite for introducing any new therapy, and the need to monitor the consequences of administration of both vector and transgene to the fetus is particularly important. The unique features of fetal development that make it an attractive target for gene therapy, such as its immature immune system and rapidly dividing populations of stem cells, also mean that small perturbations in pregnancy can have significant short- and long-term consequences. Certain features of the viral vectors used, the product of the delivered gene, and sometimes the invasive techniques necessary to deliver the construct to the fetus in utero have the potential to do harm. An important goal of prenatal gene therapy research is to develop clinically relevant techniques that could be applied to cure or ameliorate human disease in utero on large animal models such as sheep or nonhuman primates. Equally important is the use of these models to monitor for potential adverse effects of such interventions. These large animal models provide good representation of individual patient-based investigations. However, analyses that require defined genetic backgrounds, high throughput, defined variability and statistical analyses, e.g. for initial studies on teratogenic and oncogenic effects, are best performed on larger groups of small animals, in particular mice. This chapter gives an overview of the potential adverse effects in relation to prenatal gene therapy and describes the techniques that can be used experimentally in a large animal model to monitor the potential adverse consequences of prenatal gene therapy, with relevance to clinical application. The sheep model is particularly useful to allow serial monitoring of fetal growth and well-being after delivery of prenatal gene therapy. It is also amenable to serially sampling using minimally invasive and clinically relevant techniques such as ultrasound-guided blood sampling. For more invasive long-term monitoring, we describe telemetric techniques to measure the haemodynamics of the mother or fetus, for example, that interferes minimally with normal animal behaviour. Implanted catheters can also be used for serial fetal blood sampling during gestation. Finally, we describe methods to monitor events around birth and long-term neonatal follow-up that are important when considering human translation of this therapy. PMID:22648778

Mehta, Vedanta; Abi-Nader, Khalil N; Carr, David; Wallace, Jacqueline; Coutelle, Charles; Waddington, Simon N; Peebles, Donald; David, Anna L

2012-01-01

246

Large-scale integration of wind power into different energy systems  

Microsoft Academic Search

The paper presents the ability of different energy systems and regulation strategies to integrate wind power. The ability is expressed by the following three factors: the degree of electricity excess production caused by fluctuations in wind and Combined Heat and Power (CHP) heat demands, the ability to utilise wind power to reduce CO2 emission in the system, and the ability

Henrik Lund

2005-01-01

247

A Large Gene Cluster Encoding Several Magnetosome Proteins Is Conserved in Different Species of Magnetotactic Bacteria  

Microsoft Academic Search

In magnetotactic bacteria, a number of specific proteins are associated with the magnetosome membrane (MM) and may have a crucial role in magnetite biomineralization. We have cloned and sequenced the genes of several of these polypeptides in the magnetotactic bacterium Magnetospirillum gryphiswaldense that could be assigned to two different genomic regions. Except for mamA, none of these genes have been

KAREN GRUNBERG; CATHRIN WAWER; BRADLEY M. TEBO; DIRK SCHULER

2001-01-01

248

The search for large parity-violating energy differences finds fruit in thiosubstituted DNA analogues  

NASA Astrophysics Data System (ADS)

Earlier calculations of parity-violating energy differences between enantiomers (PVEDs) have produced values for typical biomolecules no larger than 10 -20 hartree, corresponding to 10 -17kT at 298 K, but in this paper we report PVEDs of 10 -17 hartree, corresponding to 10 -14kT, for thiosubstituted DNA analogues.

MacDermott, A. J.; Tranter, G. E.; Trainor, S. J.

1992-06-01

249

[Temperature compensation strategy and implementation for photoelectric modulation interferometer with large optical path difference].  

PubMed

For temperature drift in hypervelocity photoelectric modulation interferometer, a control model of temperature compensation is presented including voltage and phase compensation. First, according to the similar and modeling theory, an equivalent circuit model of mechanical properties of hypervelocity photoelectric modulation interferometer was established, the impact of temperature drift on its resonance frequency was analyzed, a mathematical model was set up, which contains drive voltage, frequency and resonance frequency, and the control method was determined for high optical path difference to get steady. Then, a digital method including voltage and phase compensation is given for optical path difference deviation control, which merges the DPLL and program of voltage and phase compensation. Finally, the control method was tested through experiment system. A test between drive control system including voltage and phase compensation and traditional drive control system was executed, using a laser doppler vibrometer to record the amount of change in optical path difference within 3 hours. Results show that the optical path difference deviation caused by temperature drift in long term is reduced by about 50%. PMID:23905367

Wang, Yan-Chao; Wang, Zhi-Bin; Zhang, Ji-Long; Chen, You-Hua

2013-05-01

250

Myoelectric activity along human gastrocnemius medialis: different spatial distributions of postural and electrically elicited surface potentials.  

PubMed

It has recently been shown that motor units in human medial gastrocnemius (MG), activated during standing, occupy relatively small territories along the muscle's longitudinal axis. Such organisation provides potential for different motor tasks to produce differing regional patterns of activity. Here, we investigate whether postural control and nerve electrical stimulation produce equal longitudinal activation patterns in MG. Myoelectric activity, at different proximal-distal locations of MG, was recorded using a linear electrode array. To ensure differences in signal amplitude between channels did not result from local, morphological factors two experimental protocols were completed: (i) quiet standing; (ii) electrical stimulation of the tibial nerve. Averaged, rectified values (ARVs) were calculated for each channel in each condition. The distribution of signals along electrode channels was described using linear regression and differences between protocols at each channel determined as the ratio between mean ARV from standing: stimulation protocols. Ratio values changed systematically across electrode channels in seven (of eight) participants, with larger values in distal channels. The distribution of ARV along MG therefore differed between experimental conditions. Compared to fibres of units activated during MG nerve stimulation, units activated during standing may have a tendency to be more highly represented in the distal muscle portion. PMID:22967836

Hodson-Tole, Emma F; Loram, Ian D; Vieira, Taian M M

2012-09-08

251

Growth differentiation factor 15 in different stages of heart failure: potential screening implications.  

PubMed

Identification of individuals in the early stage of heart failure (HF) may allow earlier initiation of disease-modifying treatment. We evaluated concentrations of the growth differentiation factor (GDF)-15 at different stages and its potential screening value in 208 subjects. Plasma GDF-15 was measured by using an enzyme-linked immunosorbent assay. GDF-15 was positively correlated with the stages of HF (r=0.804, p<0.001). In distinguishing patients with stage B HF, the area under the curve was 0.873 (p<0.001). These findings indicate that GDF-15 concentration was elevated with the progressing stages of HF and might have potential screening implications for stage B HF. PMID:20860541

Wang, Fangfang; Guo, Yanhong; Yu, Haiyi; Zheng, Lingbing; Mi, Lin; Gao, Wei

2010-09-23

252

Dynamical properties for an ensemble of classical particles moving in a driven potential well with different time perturbation  

NASA Astrophysics Data System (ADS)

We consider dynamical properties for a time-dependent potential well.The time-dependent potential well is described by different nonlinear functions.Average properties are characterised as function of the control parameters.

da Costa, Diogo Ricardo; Caldas, I. L.; Leonel, Edson D.

2013-10-01

253

Flat tree-level inflationary potentials in the light of cosmic microwave background and large scale structure data  

SciTech Connect

We use cosmic microwave background (CMB) and large scale structure (LSS) data to test a broad and physically well-motivated class of inflationary models: those with flat tree-level potentials (typical in supersymmetry). The non-trivial features of the potential arise from radiative corrections which give a simple logarithmic dependence on the inflaton field, making the models very predictive. We also consider a modified scenario with new physics beyond a certain high energy cut-off showing up as non-renormalizable operators (NRO) in the inflaton field. We find that both kinds of models fit CMB and LSS data remarkably well, with very few free parameters. Besides, many of these models naturally predict a reasonable number of e-folds. A robust feature of these scenarios is the smallness of tensor perturbations (r{approx}<10{sup -3}). The NRO case can give a sizable running of the spectral index while achieving a sufficient number of e-folds. We use Bayesian model comparison tools to assess the relative performance of the models. We believe that these scenarios can be considered as a standard physical class of inflationary models, on a similar footing to monomial potentials.

Ballesteros, G; Casas, J A; Espinosa, J R; Ruiz de Austri, R [IFT-UAM/CSIC, UAM, Cantoblanco, 28049 Madrid (Spain); Trotta, R, E-mail: guillermo.ballesteros@uam.es, E-mail: alberto.casas@uam.es, E-mail: jose.espinosa@cern.ch, E-mail: rruiz@delta.ft.uam.es, E-mail: rxt@astro.ox.ac.uk [Astrophysics Department, Oxford University, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom)

2008-03-15

254

Large difference between two methods of calculating the integrated fermi function in superallowed ?-decays  

NASA Astrophysics Data System (ADS)

The integrated statistical rates for superallowed 0+-0+ ?-transitions evaluated according to the most widely used methods proposed by Behrens-Jänecke-Bühring and Towner-Hardy are compared. It is shown that both calculations are in essential agreement up to mass A=38. However, for heavier nuclei there is a discrepancy. The disagreement, which increases with increasing Z, ranges from 0.07% for 42Sc to as much as 0.13% for 54Co and is larger than the errors attached to f-values due to uncertainties in W0 (these being about 0.03-0.04%). Moreover, such differences are either comparable to or even larger than the uncertainties in t and ?c. The disagreement is attributed to the different evaluations of the second-forbidden nuclear matrix elements. The choice of the parameters used in both methods is also discussed.

Szybisz, L.; Silbergleit, V. M.; Sidelnik, J. I.

1983-03-01

255

Modeling the large-scale water balance impact of different irrigation systems  

Microsoft Academic Search

(1) In this study, two parameterizations for different irrigation techniques have been implemented in a regional climate model. These implementations allow for a comparative study of water use and land-atmosphere interactions associated with traditional flood irrigation—a widespread but highly water-inefficient practice—and water-conserving drip irrigation. Both parameterizations yield realistic results for coupled climate simulations, and do so without the need to

J. P. Evans; B. F. Zaitchik

2008-01-01

256

Modeling the large-scale water balance impact of different irrigation systems  

Microsoft Academic Search

In this study, two parameterizations for different irrigation techniques have been implemented in a regional climate model. These implementations allow for a comparative study of water use and land–atmosphere interactions associated with traditional flood irrigation—a widespread but highly water-inefficient practice—and water-conserving drip irrigation. Both parameterizations yield realistic results for coupled climate simulations, and do so without the need to reproduce

J. P. Evans; B. F. Zaitchik

2008-01-01

257

Supplier involvement in automotive component design: are there really large US Japan differences?  

Microsoft Academic Search

Typical descriptions of Japanese supplier management portray first-tier suppliers as partners in product development from the early concept stages of design, whereas US first-tier suppliers are provided detailed specifications and blueprints and build to print. This paper examines US\\/Japan differences in supplier involvement in design based on a 1993 survey of 143 Japanese and 189 US automotive component suppliers. The

Jeffrey K. Liker; Rajan R. Kamath; S. Nazli Wasti; Mitsuo Nagamachi

1996-01-01

258

Cross-polar cap potential difference, auroral electrojet indices, and solar wind parameters  

SciTech Connect

The cross-polar cap potential difference {Phi} (KRM) is estimated from ground magnetic perturbation data through the magnetometer inversion method of Kamide, Richmond, and Matsushita (FRM), combined with an empirical ionospheric conductance distribution estimated from the DMSP X ray image data. A significant correlation is found between {Phi} (KRM) and the AE(12) index. {Phi} (KRM) is then compared with the potential difference estimated from a more direct method of the satellite electric field measurements and also with {Phi}(IMF) is found to be linearly correlated with {Phi} (IMF) based on solar wind parameters. {Phi} IMF is found to be linearly correlated with {Phi}(KRM), as {Phi}(IMF) = 29.8 + 0.999 {Phi} (KRM), with the highest correlation obtained for a 40-min lag in the interplanetary magnetic field (IMF). Note that {Phi}(IMF) is systematically larger than {Phi} (KRM) by 30 kV, suggesting the possibility that the theoretical method overestimates the cross-polar cap potential difference. During steady southward IMF periods were steady {Phi} (IMF) variations are expected, significant fluctuations in calculated {Phi} (KRM) values are obtained. Since the decrease in {Phi} (KRM) is closely associated with enhancements in auroral particle precipitation during these periods, a highly correlative relation between {Phi} (IMF) and {Phi} (KRM) cannot be deduced unless the phases of substorms are taken into account. The overall high correlation between them, however, supports the view expressed by Wolf et al. (1986) that directly driven processes are more important than unloading processes during disturbed periods.

Ahn, B.H. (Kyungpook National Univ., Taegu (Korea) Univ. of Colorado, Boulder (United States)); Kamide, Y. (Kyoto Sangyo Univ., (Japan)); Kroehl, H.W.; Gorney, D.J. (Aerospace Corp., Los Angeles, CA (United States))

1992-02-01

259

Intraurban Differences in the Use of Ambulatory Health Services in a Large Brazilian City  

PubMed Central

A major goal of health systems is to reduce inequities in access to services, that is, to ensure that health care is provided based on health needs rather than social or economic factors. This study aims to identify the determinants of health services utilization among adults in a large Brazilian city and intraurban disparities in health care use. We combine household survey data with census-derived classification of social vulnerability of each household’s census tract. The dependent variable was utilization of physician services in the prior 12 months, and the independent variables included predisposing factors, health needs, enabling factors, and context. Prevalence ratios and 95% confidence intervals were estimated by the Hurdle regression model, which combined Poisson regression analysis of factors associated with any doctor visits (dichotomous variable) and zero-truncated negative binomial regression for the analysis of factors associated with the number of visits among those who had at least one. Results indicate that the use of health services was greater among women and increased with age, and was determined primarily by health needs and whether the individual had a regular doctor, even among those living in areas of the city with the worst socio-environmental indicators. The experience of Belo Horizonte may have implications for other world cities, particularly in the development and use of a comprehensive index to identify populations at risk and in order to guide expansion of primary health care services as a means of enhancing equity in health.

Lima-Costa, Maria Fernanda; Proietti, Fernando Augusto; Cesar, Cibele C.; Macinko, James

2010-01-01

260

Expression of Twist gene in human hepatocellular carcinoma cell strains of different metastatic potential  

Microsoft Academic Search

Summary  In order to investigate the role of Twist gene in the metastasis of hepatocellular carcinoma (HCC), total RNA was respectively\\u000a extracted from three HCC cell strains with different metastatic potentials, HepG2, MHCC-97L and MHCC-97H. The first strand\\u000a cDNA was synthesized by reverse transcription, which was then used as template to perform fluorescent quantitative polymerase\\u000a chain reaction (FQ-PCR). The quantity of

Qian Zhu; Hubo Xu; Qian Xu; Wei Yan; De’an Tian

2008-01-01

261

Different effect of Rho kinase inhibition on calcium signaling in rat isolated large and small arteries.  

PubMed

In addition to its role in the regulation of artery contraction, Rho kinase (ROCK) was reported to be involved in the cytosolic calcium response to vasoconstrictor agonists in rat aorta and superior mesenteric artery (SMA). However, it remains to be determined whether ROCK also contributes to calcium signaling in resistance arteries, which play a major role in blood pressure regulation. The investigation of the effect of ROCK inhibition on the calcium and contractile responses of rat resistance mesenteric artery (RMA), in comparison with aorta and SMA, indicated that the calcium response to noradrenaline was inhibited by the ROCK inhibitor Y-27632 in aorta and SMA but not in RMA. The effect of Y-27632 on the calcium signal was unaffected by cytochalasin-D. ROCK activation in noradrenaline-stimulated arteries was confirmed by the inhibition of myosin light chain phosphorylation by Y-27632. Moreover, noradrenaline-induced calcium signaling was similarly inhibited by nimodipine in aorta, SMA and RMA, but nimodipine sensitivity of the contraction increased from the aorta to the RMA, suggesting that the contraction was controlled by different sources of calcium. In pressurized RMA, Y-27632 and H-1152 depressed pressure-induced calcium responses and abolished myogenic contraction. These results stress the important differences in calcium signaling between conductance and resistance arteries. PMID:22948674

Martinsen, Anneloes; Yerna, Xavier; Rath, Géraldine; Gomez, Elvira Leon; Dessy, Chantal; Morel, Nicole

2012-09-01

262

Gravity wave kinetic, potential, and vertical fluctuation energies as indicators of different frequency gravity waves  

NASA Astrophysics Data System (ADS)

An advantage of examining atmospheric gravity waves using high vertical-resolution radiosonde data over other measurement techniques is that horizontal wind, temperature, and vertical ascent rate can be measured directly. This allows the kinetic, potential, and vertical velocity fluctuation energies to be derived independently. Each of these gravity wave energies is shown to have sensitivity to different gravity wave frequencies. Observed correlations among these energies are consistent with this, and simulations of these correlations are shown to constrain gravity wave frequency spectra. The climatology of these energies shows quite different variations with month of the year and with latitude such that the vertical fluctuation energy seems to be a better indicator of convectively forced higher-frequency gravity waves.

Geller, Marvin A.; Gong, Jie

2010-06-01

263

P300 EVENT RELATED POTENTIAL IN NORMAL HEALTHY CONTROLS OF DIFFERENT AGE GROUPS  

PubMed Central

P300 event related potential was recorded in 115 healthy controls with a mean age of35.9±14.81 years and a male : female ratio of 72 : 43. There was significant difference in the P300 latency in < 40 years as compared to ? 40 years group (p< 0.001). There was no significant difference between males and females. There was a strong positive correlation between age and P300 latency (p< 0.001). The regression equation for P300 latency was Y=287.9+1.492x with an SEE of 20.2 (where Y is the P300 latency in ms, x is the age in years, SEE is the standard error of estimate). There was a negative correlation between age and P300 amplitude which was significant in ? 40 years age group while in > 40 years age group it was not significant.

Shukla, R.; Trivedi, J.K.; Singh, R.; Singh, Y.; Chakravorty, P.

2000-01-01

264

Estimating sugarcane yield potential using an in-season determination of normalized difference vegetative index.  

PubMed

Estimating crop yield using remote sensing techniques has proven to be successful. However, sugarcane possesses unique characteristics; such as, a multi-year cropping cycle and plant height-limiting for midseason fertilizer application timing. Our study objective was to determine if sugarcane yield potential could be estimated using an in-season estimation of normalized difference vegetative index (NDVI). Sensor readings were taken using the GreenSeeker® handheld sensor from 2008 to 2011 in St. Gabriel and Jeanerette, LA, USA. In-season estimates of yield (INSEY) values were calculated by dividing NDVI by thermal variables. Optimum timing for estimating sugarcane yield was between 601-750 GDD. In-season estimated yield values improved the yield potential (YP) model compared to using NDVI. Generally, INSEY value showed a positive exponential relationship with yield (r(2) values 0.48 and 0.42 for cane tonnage and sugar yield, respectively). When models were separated based on canopy structure there was an increase the strength of the relationship for the erectophile varieties (r(2) 0.53 and 0.47 for cane tonnage and sugar yield, respectively); however, the model for planophile varieties weakened slightly. Results of this study indicate using an INSEY value for predicting sugarcane yield shows potential of being a valuable management tool for sugarcane producers in Louisiana. PMID:22969359

Lofton, Josh; Tubana, Brenda S; Kanke, Yumiko; Teboh, Jasper; Viator, Howard; Dalen, Marilyn

2012-06-04

265

Estimating Sugarcane Yield Potential Using an In-Season Determination of Normalized Difference Vegetative Index  

PubMed Central

Estimating crop yield using remote sensing techniques has proven to be successful. However, sugarcane possesses unique characteristics; such as, a multi-year cropping cycle and plant height-limiting for midseason fertilizer application timing. Our study objective was to determine if sugarcane yield potential could be estimated using an in-season estimation of normalized difference vegetative index (NDVI). Sensor readings were taken using the GreenSeeker® handheld sensor from 2008 to 2011 in St. Gabriel and Jeanerette, LA, USA. In-season estimates of yield (INSEY) values were calculated by dividing NDVI by thermal variables. Optimum timing for estimating sugarcane yield was between 601–750 GDD. In-season estimated yield values improved the yield potential (YP) model compared to using NDVI. Generally, INSEY value showed a positive exponential relationship with yield (r2 values 0.48 and 0.42 for cane tonnage and sugar yield, respectively). When models were separated based on canopy structure there was an increase the strength of the relationship for the erectophile varieties (r2 0.53 and 0.47 for cane tonnage and sugar yield, respectively); however, the model for planophile varieties weakened slightly. Results of this study indicate using an INSEY value for predicting sugarcane yield shows potential of being a valuable management tool for sugarcane producers in Louisiana.

Lofton, Josh; Tubana, Brenda S.; Kanke, Yumiko; Teboh, Jasper; Viator, Howard; Dalen, Marilyn

2012-01-01

266

How does error correction differ from error signaling? An event-related potential study.  

PubMed

It has been a question of debate whether immediate error corrections in speeded forced-choice reaction time tasks require an error detection signal from the performance monitoring system or whether they reflect delayed correct responses that are executed after the premature error like in a horserace. In contrast, signaling the error by pressing a response button that is unrelated to the primary task is based on error detection. The present study investigates the similarities and differences between immediate error corrections and signaling responses by means of behavioral and event-related potential data. In a within-subject design, participants performed two sessions of the flanker task. In one session, errors had to be corrected by immediately pressing the correct response, in the other session, errors had to be signaled by pressing an error signaling button. Compared to the signaling session, in the correction session, more errors and error corrections were made, reaction times were shorter, and the amplitude of the error-related negativity (ERN) was reduced. Whereas the error significance did not seem to differ across session, participants have most likely reduced the motor threshold in the correction session to enable efficient immediate corrections. This interpretation is supported by the lateralized readiness potentials and is consistent with the response conflict monitoring hypothesis of the ERN. The present study demonstrates that differences in error corrections may be attributable to differences in motor threshold. We conclude that the error signaling procedure is a more direct and reliable way to behaviorally test the functional integrity of the performance monitoring system than the instruction to correct errors. The consequences for studies in patients and with pharmacological challenges are discussed. PMID:16483557

Ullsperger, Markus; von Cramon, D Yves

2006-02-17

267

Potentiation of large conductance, Ca2+-activated K+ (BK) channels by ?5?1 integrin activation in arteriolar smooth muscle  

PubMed Central

Injury/degradation of the extracellular matrix (ECM) is associated with vascular wall remodelling and impaired reactivity, a process in which altered ECM–integrin interactions play key roles. Previously, we found that peptides containing the RGD integrin-binding sequence produce sustained vasodilatation of rat skeletal muscle arterioles. Here, we tested the hypothesis that RGD ligands work through ?5?1 integrin to modulate the activity of large conductance, Ca2+-activated K+ (BK) channels in arteriolar smooth muscle. K+ currents were recorded in single arteriolar myocytes using whole-cell and single-channel patch clamp methods. Activation of ?5?1 integrin by an appropriate, insoluble ?5?1 antibody resulted in a 30–50% increase in the amplitude of iberiotoxin (IBTX)-sensitive, whole-cell K+ current. Current potentiation occurred 1–8 min after bead–antibody application to the cell surface. Similarly, the endogenous ?5?1 integrin ligand fibronectin (FN) potentiated IBTX-sensitive K+ current by 26%. Current potentiation was blocked by the c-Src inhibitor PP2 but not by PP3 (0.1–1 ?m). In cell-attached patches, number of open channels × open probability (NPo) of a 230–250 pS K+ channel was significantly increased after FN application locally to the external surface of cell-attached patches through the recording pipette. In excised, inside-out patches, the same method of FN application led to large, significant increases in NPo and caused a leftward shift in the NPo–voltage relationship at constant [Ca2+]. PP2 (but not PP3) nearly abolished the effect of FN on channel activity, suggesting that signalling between the integrin and channel involved an increase in Ca2+sensitivity of the channel via a membrane-delimited pathway. The effects of ?5?1 integrin activation on both whole-cell and single-channel BK currents could be reproduced in HEK 293 cells expressing the BK channel ?-subunit. This is the first demonstration at the single-channel level that integrin signalling can regulate an ion channel. Our results show that ?5?1 integrin activation potentiates BK channel activity in vascular smooth muscle through both Ca2+- and c-Src-dependent mechanisms. This mechanism is likely to play a role in the arteriolar dilatation and impaired vascular reactivity associated with ECM degradation.

Wu, Xin; Yang, Yan; Gui, Peichun; Sohma, Yoshiro; Meininger, Gerald A; Davis, George E; Braun, Andrew P; Davis, Michael J

2008-01-01

268

Individual differences in interhemispheric transfer time (IHTT) as measured by event related potentials.  

PubMed

The present study examined possible gender differences in interhemisperic transfer time (IHTT), as measured by event related potentials (ERPs). Using visual half-field presentations of letter pairs in a match/no-match paradigm, N1 latency was measured for each visual half-field and hemisphere. IHTTs were determined by subtracting the "direct" (i.e., contralateral or non-callosal) pathway N1 latency from the "indirect" (i.e., callosal) pathway N1 latency. Based on studies showing gender differences in corpus callosum size and function, we hypothesized that females would show more symmetric and faster overall transfer times than males. Results showed faster right-to-left IHTT across all participants, but females had more symmetric IHTT and shorter overall IHTT--primarily due to significantly shorter left-to-right times compared to males. Little support was found for the influence of hemisphere (i.e., "direct" pathway) response, or potential lateralization of function, on the length of IHTT in either direction. PMID:17499316

Moes, Paul E; Brown, Warren S; Minnema, Michael T

2007-03-27

269

The role of the transbranchial potential difference in hyperosmotic regulation of the shore crab Carcinus maenas  

NASA Astrophysics Data System (ADS)

When isolated gills of the shore crab Carcinus maenas were bathed and perfused with identical solutions on both sides (50 % sea water), a spontaneous transepithelial potential difference (PD) of some millivolts (hemolymph side negative) was established. This PD is of active nature and requires the metabolism of the living cell, since it uses its own sources of energy in addition to organic nutrients offered in the flow of artificial hemolymph. Addition of sodium cyanide and dinitrophenole to bathing and perfusion medium resulted in reversible breakdown of PDs in a concentration-dependent mode. In posterior gills of C. maenas, the potential differences were more negative compared to data measured in anterior gills of the same individuals. These results are correlated with higher specific activities of Na-K-ATPase in posterior gills. Experiments with triamterene indicate that sodium uptake in C. maenas is sensitive to this diuretic drug, when applied on the apical side of the epithelial cell. The results obtained show that active uptake of sodium from medium to blood across the gills is performed by a complex mechanism including participation of several basal and apical transport steps.

Winkler, Andreas

1986-03-01

270

Liquid Hole-Multipliers: A potential concept for large single-phase noble-liquid TPCs of rare events  

NASA Astrophysics Data System (ADS)

A novel concept is proposed for large-volume single-phase noble-liquid TPC detectors for rare events. Both radiation-induced scintillation-light and ionization-charge are detected by Liquid Hole-Multipliers (LHM), immersed in the noble liquid. The latter may consist of cascaded Gas Electron Multipliers (GEM), Thick Gas Electron Multiplier (THGEM) electrodes or others, coated with CsI UV-photocathodes. Electrons, photo-induced on CsI by primary scintillation in the noble liquid, and event-correlated drifting ionization electrons are amplified in the cascaded elements primarily through electroluminescence, and possibly through additional moderate avalanche, occurring within the holes. The resulting charge-signals or light-pulses are recorded on anode pads or with photosensors - e.g. gaseous photomultipliers (GPM), respectively. Potential affordable solutions are proposed for multi-ton dark-matter detectors; open questions are formulated for validating this dream.

Breskin, Amos

2013-10-01

271

The "Large" in Large Igneous Provinces: Using Digital Geological Maps to Determine the Area, Magma Flux, and Potential Environmental Impact of the Wrangellia Flood Basalts  

NASA Astrophysics Data System (ADS)

Large igneous provinces (LIPs), such as continental flood basalts and oceanic plateaus, are formed by relatively short duration, massive outpourings of basalt in intraplate settings. Their emplacement has been associated with global climatic and biotic change (e.g., end-Permian Siberian LIP). The magmatic products of a LIP typically cover an area >1 Mkm2, however erosion and exhumation may substantially reduce the original area and volume of a LIP, especially oceanic plateaus that have been tectonically dispersed during accretion (e.g., Caribbean, Wrangellia). The availability of digital geologic maps from government geologic surveys now allows for measuring the precise areal distribution of remnant LIP-products, which is essential information for estimating total volumes and ultimately potential environmental effects. The Wrangellia flood basalts represent one of the best-exposed accreted oceanic plateaus on Earth. This Triassic LIP is exposed in numerous fault-bound blocks in a belt extending discontinuously for 2300 km in the Pacific Northwest of North America. It contains exposures of submarine and subaerial volcanic rocks representing composite stratigraphic thicknesses of 3.5-6 km. From recently compiled digital geologic maps (British Columbia, Yukon, Alaska), the mapped exposures of the Wrangellia flood basalts are relatively small (25,256 km2 with 75% from Vancouver Island), which leads to minimum calculated erupted volumes of up to 1.4 x 105 km3 and an estimated magma flux of 0.03 km3/yr. The original areal distribution was substantially greater, perhaps by an order of magnitude or more, as the outcrop extent does not include regions covered by younger strata and surficial deposits nor does it account for the volcanic component of the terrane that may have been subducted. However, even this minimum volumetric output rate is comparable to recent estimates of long-term volumetric eruption rates for ocean islands such as Iceland (0.02-0.04 km3/yr) and Hawaii (0.02-0.08 km3/yr) [1]. The Wrangellia flood basalts were emplaced during a single phase of tholeiitic volcanism at ca. 230 Ma, possibly within as few as 2 Myr, onto preexisting submerged arc crust in equatorial latitudes in the eastern Panthalassic Ocean. This age corresponds to the Carnian-Norian boundary of the Upper Triassic [2], a time of global-scale climatic and biotic crisis, which was followed by strong radiation of the dinosaurs. A combination of precise U-Pb geochronology of the Wrangellia basalts, area/magma flux estimates (including integration of geophysical seismic reflection profiles to account for plutonic components) and quantification of the associated volatile production will be required to fully evaluate this potential link between volcanic activity and global environmental impacts. [1] White, S.M. et al. (2006) Geochemistry Geophysics Geosystems, 7, Q03010, doi: 10.1029/2005GC001002. [2] Furin, S. et al. (2006) Geology 34, 1009-1012, doi: 10.1130/G22967A.1.

Scoates, J. S.; Greene, A. R.; Weis, D. A.

2010-12-01

272

Annual surveys of larval Ambystoma cingulatum reveal large differences in dates of pond residency  

SciTech Connect

Effective sampling of pond-dwelling larval stages of the federally listed Ambystoma cingulatum (Flatwoods Salamander) requires sufficient knowledge of when larvae are present and how best to sample them. Through systematic sampling with active and passive sampling techniques, we found dipnetting to be significantly more effective than three types of passive traps. During surveys for Flatwoods Salamander larvae at Fort Stewart Military Installation, GA in 2005 and 2006, we found that pond residency varied by at least 1.5 months between the 2 years due to the timing of pond filling. In addition, our latest capture on 23 May 2005 was about 2 weeks later than previously recorded at any site range-wide. A simple growth model was used to evaluate likely hatching dates based on significant rain events, observed sizes at capture, and likely growth rates. This analysis suggested that the primary dates of hatching occurred in late February 2005 and early January 2006, a difference that corresponds to that seen in the residency of the latest larval stages. A review of the survey records for Fort Stewart for the past 13 years shows a steep decline in the number of occupied ponds from near 20 to a single pond for the past two years (the only documented breeding success in a natural pond since 1999).

Bevelhimer, Mark S [ORNL; Giffen, Neil R [ORNL; Stevenson, Dirk [Ft Stewart Fish and Wildlife Branch

2008-05-01

273

A Large Gene Cluster Encoding Several Magnetosome Proteins Is Conserved in Different Species of Magnetotactic Bacteria  

PubMed Central

In magnetotactic bacteria, a number of specific proteins are associated with the magnetosome membrane (MM) and may have a crucial role in magnetite biomineralization. We have cloned and sequenced the genes of several of these polypeptides in the magnetotactic bacterium Magnetospirillum gryphiswaldense that could be assigned to two different genomic regions. Except for mamA, none of these genes have been previously reported to be related to magnetosome formation. Homologous genes were found in the genome sequences of M. magnetotacticum and magnetic coccus strain MC-1. The MM proteins identified display homology to tetratricopeptide repeat proteins (MamA), cation diffusion facilitators (MamB), and HtrA-like serine proteases (MamE) or bear no similarity to known proteins (MamC and MamD). A major gene cluster containing several magnetosome genes (including mamA and mamB) was found to be conserved in all three of the strains investigated. The mamAB cluster also contains additional genes that have no known homologs in any nonmagnetic organism, suggesting a specific role in magnetosome formation.

Grunberg, Karen; Wawer, Cathrin; Tebo, Bradley M.; Schuler, Dirk

2001-01-01

274

Large strain rate-dependent response of elastomers at different strain rates: convolution integral vs. internal variable formulations  

NASA Astrophysics Data System (ADS)

Two different viscoelastic frameworks adapted to large strain rate-dependent response of elastomers are compared; for each approach, a simple model is derived. Within the Finite Linear Viscoelasticity theory, a time convolution integral model based on an extension to solid of the K-BKZ model is proposed. Considering the multiplicative split of the deformation gradient into elastic and inelastic parts, an internal variable model based on a large strain version of the Standard Linear Solid model is considered. In both cases, the strain energy functions involved are chosen neo-Hookean, and then each model possesses three material parameters: two stiffnesses and a viscosity parameter. These parameters are set to ensure the equivalence of the model responses for uniaxial large strain quasi-static and infinitely fast loading conditions, and for uniaxial rate-dependent small strain loading conditions. Considering their responses for different Eulerian strain rates, their differences are investigated with respect to the strain rate; more specifically, both stiffness and dissipative properties are studied. The comparison reveals that these two models differ significantly for intermediate strain rates, and a closing discussion highlights some issues about their foundations and numerical considerations.

Petiteau, J.-C.; Verron, E.; Othman, R.; Le Sourne, H.; Sigrist, J.-F.; Barras, G.

2013-08-01

275

Potential Large Animal Models for Gene Therapy of Human Genetic Diseases of Immune and Blood Cell Systems  

PubMed Central

Genetic mutations involving the cellular components of the hematopoietic system—red blood cells, white blood cells, and platelets—manifest clinically as anemia, infection, and bleeding. Although gene targeting has recapitulated many of these diseases in mice, these murine homologues are limited as translational models by their small size and brief life span as well as the fact that mutations induced by gene targeting do not always faithfully reflect the clinical manifestations of such mutations in humans. Many of these limitations can be overcome by identifying large animals with genetic diseases of the hematopoietic system corresponding to their human disease counterparts. In this article, we describe human diseases of the cellular components of the hematopoietic system that have counterparts in large animal species, in most cases carrying mutations in the same gene (CD18 in leukocyte adhesion deficiency) or genes in interacting proteins (DNA cross-link repair 1C protein and protein kinase, DNA-activated, catalytic polypeptide in radiation-sensitive severe combined immunodeficiency). Furthermore, we describe the potential of these animal models to serve as disease-specific, preclinical models for testing the efficacy and safety of clinical interventions such as hematopoietic stem cell transplantation or gene therapy approaches before their use in humans with the corresponding disease.

Bauer, Thomas R.; Adler, Rima L.; Hickstein, Dennis D.

2009-01-01

276

Very large difference in electronic communication of dimetal species with heterobiphenylene and heteroanthracene units.  

PubMed

Two neutral compounds having [Mo2] units linked by squarate dianions, [Mo2(DAniF)3]2(mu4-C4O4) (DAniF = N,N'-di(p-anisyl)formamidinate) (1) and [Mo2(DmCF3F)3]2(mu4-C4O4) (DmCF3F = N,N'-di(m-trifluoromethylphenyl)formamidinate) (2), as well as the singly oxidized compound {[Mo2(DmCF3F)3]2(mu4-C4O4)}SbF6 (3) and the doubly oxidized species {[Mo2(DAniF)3]2(mu4-C4O4)}(TFPB)2 (TFPB = [B(3,5-(CF3)2C6H3)4]-) (4), were synthesized and structurally characterized. Electrochemical measurements of the two neutral species showed only very weak electronic interactions between the two dimolybdenum units linked by the squarate anion in contrast to what was observed in dioxolene analogues having C6 instead of C4 rings (J. Am. Chem. Soc. 2006, 128, 3281) which led to differences in comproportionation constants of over 108. In the squarate species, the pi electrons are localized within the carbonyl and dimetal units in the heterometallic six-membered Mo2O2C2 rings to minimize the antiaromaticity in the central C4 square. The oxidized species 3 and 4 are electronically localized in the time scale of the physical measurements. Calculations at the DFT level suggested that the energy mismatch of the frontier orbitals of the linker and dimetal units contributes to the weak communication between the Mo2 units. For the doubly oxidized complex 4, DFT calculations gave a J value of -130 cm(-1) which suggests that the two unpaired electrons are only weakly antiferromagnetically coupled, as shown by magnetic studies (J = -121 cm(-1)). PMID:18076161

Cotton, F Albert; Murillo, Carlos A; Young, Mark D; Yu, Rongmin; Zhao, Qinliang

2007-12-13

277

Racial differences in clinical use of cinacalcet in a large population of hemodialysis patients.  

PubMed

Background/Aims: African-Americans with end-stage renal disease receiving dialysis have more severe secondary hyperparathyroidism than Whites. We aimed to assess racial differences in clinical use of cinacalcet. Methods: This retrospective cohort study used data from DaVita, Inc., for 45,589 prevalent hemodialysis patients, August 2004, linked to Centers for Medicare & Medicaid Services data, with follow-up through July 2007. Patients with Medicare as primary payer, intravenous vitamin D use, or weighted mean parathyroid hormone (PTH) level >150 pg/ml at baseline (August 1-October 31, 2004) were included. Cox proportional hazard modeling was used to evaluate race and other demographic and clinical characteristics as predictors of cinacalcet initiation, titration, and discontinuation. Results: Of 16,897 included patients, 7,674 (45.4%) were African-American and 9,223 (54.6%) were white; 53.2% of cinacalcet users were African-American. Cinacalcet was prescribed for 47.7% of African-Americans and 34.5% of Whites, and for a greater percentage of African-Americans at higher doses at each PTH strata. After covariate adjustment, African-Americans were more likely than Whites to receive cinacalcet prescriptions (hazard ratio 1.17, p < 0.001). The direction and magnitude of this effect appeared to vary by age, baseline PTH, and calcium, and by elemental calcium use. African-Americans were less likely than Whites to have prescriptions discontinued and slightly more likely to undergo uptitration (hazard ratio 1.09, 95% confidence interval 0.995-1.188), but this relationship lacked statistical significance. Conclusion: Cinacalcet is prescribed more commonly and at higher initial doses for African-Americans than for Whites to manage secondary hyperparathyroidism. © 2013 S. Karger AG, Basel. PMID:23899621

Newsome, Britt B; Kilpatrick, Ryan D; Liu, Jiannong; Zaun, David; Solid, Craig A; Nieman, Kimberly; St Peter, Wendy L

2013-07-30

278

Advances towards using finger/toenail dosimetry to triage a large population after potential exposure to ionizing radiation  

PubMed Central

Rapid and accurate retrospective dosimetry is of critical importance and strategic value for the emergency medical response to a large-scale radiological/nuclear event. One technique that has the potential for rapid and accurate dosimetry measurements is electron paramagnetic resonance (EPR) spectroscopy of relatively stable radiation-induced signals (RIS) in fingernails and toenails. Two approaches are being developed for EPR nail dosimetry. In the approach using ex vivo measurements on nail clippings, accurate estimation of the dose-dependent amplitude of the RIS is complicated by the presence of mechanically-induced signals (MIS) that are generated during the nail clipping. Recent developments in ex vivo nail dosimetry, including a thorough characterization of the MIS and an appreciation of the role of hydration and the development of effective analytic techniques, have led to improvements in the accuracy and precision of this approach. An in vivo nail dosimetry approach is also very promising, as it eliminates the problems of MIS from the clipping and it has the potential to be an effective and efficient approach for field deployment. Two types of EPR resonators are being developed for in vivo measurements of fingernails and toenails.

He, Xiaoming; Gui, Jiang; Matthews, Thomas P.; Williams, Benjamin B.; Swarts, Steven G.; Grinberg, Oleg; Sidabras, Jason; Wilcox, Dean E.; Swartz, Harold M.

2011-01-01

279

Reconstruction of Oomycete Genome Evolution Identifies Differences in Evolutionary Trajectories Leading to Present-Day Large Gene Families  

PubMed Central

The taxonomic class of oomycetes contains numerous pathogens of plants and animals but is related to nonpathogenic diatoms and brown algae. Oomycetes have flexible genomes comprising large gene families that play roles in pathogenicity. The evolutionary processes that shaped the gene content have not yet been studied by applying systematic tree reconciliation of the phylome of these species. We analyzed evolutionary dynamics of ten Stramenopiles. Gene gains, duplications, and losses were inferred by tree reconciliation of 18,459 gene trees constituting the phylome with a highly supported species phylogeny. We reconstructed a strikingly large last common ancestor of the Stramenopiles that contained ?10,000 genes. Throughout evolution, the genomes of pathogenic oomycetes have constantly gained and lost genes, though gene gains through duplications outnumber the losses. The branch leading to the plant pathogenic Phytophthora genus was identified as a major transition point characterized by increased frequency of duplication events that has likely driven the speciation within this genus. Large gene families encoding different classes of enzymes associated with pathogenicity such as glycoside hydrolases are formed by complex and distinct patterns of duplications and losses leading to their expansion in extant oomycetes. This study unveils the large-scale evolutionary dynamics that shaped the genomes of pathogenic oomycetes. By the application of phylogenetic based analyses methods, it provides additional insights that shed light on the complex history of oomycete genome evolution and the emergence of large gene families characteristic for this important class of pathogens.

Seidl, Michael F.; Van den Ackerveken, Guido; Govers, Francine; Snel, Berend

2012-01-01

280

Evaluating the Potential of Retrieving Vertically-Resolved Cloud Drop Microphysical Properties From APS/RSP Polarization Measurements Combined With Lidar and Radar Using Large-Eddy Simulations  

NASA Astrophysics Data System (ADS)

Multi-spectral, multi-directional polarimetric measurements, such as those made by the Aerosol Polarimetry Sensor (APS) on the forthcoming Glory satellite mission, coupled with co-located CALIPSO/CLOUDSAT lidar and radar measurements have great potential in retrieving accurate information about cloud droplet number concentrations and the vertical distribution of cloud liquid water content, which are crucial quantities for studies on, e.g., indirect aerosol effects. A cloud retrieval algorithm making use of such a combination of measurements has been developed and tested on measurements of an aircraft-mounted version of APS, the Research Scanning Polarimeter (RSP),in combination with aircraft-based lidar and radar measurements. However, validating the retrieval results can be challenging due to lack of validation data or the difficulty of interpreting and comparing retrieval results from different instruments. In this presentation we present an additional validation approach in which APS/RSP, lidar and radar measurements are simulated based on large-eddy simulations of marine stratocumulus fields in various atmospheric conditions. By comparing the quantities retrieved from these simulated measurement with the true values from the large-eddy simulations, we will demonstrate the potential and limitations of this retrieval approach.

Cairns, B.; van Diedenhoven, B.; Ackerman, A. S.

2009-12-01

281

Variations of surface water extent and water storage in large river basins: A comparison of different global data sources  

NASA Astrophysics Data System (ADS)

For the period 2003-2004 and for six large river basins, the present study compares monthly time series of multi-satellite-derived surface water extent with other independent global data sets related to land water dynamics, such as water mass variations monitored by GRACE, simulated surface and total water storage from WGHM, water levels from altimetry, and GPCP precipitation estimates. In general, the datasets show a strong agreement with each other at seasonal timescale. In particular, over the Amazon and the Ganges basins, analysis of seasonal phase differences and hysteresis behavior between surface water extent, water level and storage reveal the complex relations between water extent and storage variations and the different effects of water transport processes within large river basins. The results highlight the value of combining multi-satellite techniques for retrieving surface water storage dynamics.

Papa, F.; Güntner, A.; Frappart, F.; Prigent, C.; Rossow, W. B.

2008-06-01

282

Differences in kainate receptor involvement in hippocampal mossy fibre long-term potentiation depending on slice orientation.  

PubMed

Long-term potentiation (LTP) is a well-established experimental model used to investigate the synaptic basis of learning and memory. LTP at mossy fibre - CA3 synapses in the hippocampus is unusual because it is normally N-methyl-d-aspartate (NMDA) receptor-independent. Instead it seems that the trigger for mossy fibre LTP involves kainate receptors (KARs). Although it is generally accepted that pre-synaptic KARs play an essential role in frequency facilitation and LTP, their subunit composition remains a matter of significant controversy. We have reported previously that both frequency facilitation and LTP can be blocked by selective antagonism of GluK1 (formerly GluR5/Glu(K5))-containing KARs, but other groups have failed to reproduce this effect. Moreover, data from receptor knockout and mRNA expression studies argue against a major role of GluK1, supporting a more central role for GluK2 (formerly GluR6/Glu(K6)). A potential reason underlying the controversy in the pharmacological experiments may reside in differences in the preparations used. Here we show differences in pharmacological sensitivity of synaptic plasticity at mossy fibre - CA3 synapses depend critically on slice orientation. In transverse slices, LTP of fEPSPs was invariably resistant to GluK1-selective antagonists whereas in parasagittal slices LTP was consistently blocked by GluK1-selective antagonists. In addition, there were pronounced differences in the magnitude of frequency facilitation and the sensitivity to the mGlu2/3 receptor agonist DCG-IV. Using anterograde labelling of granule cells we show that slices of both orientations possess intact mossy fibres and both large and small presynaptic boutons. Transverse slices have denser fibre tracts but a smaller proportion of giant mossy fibre boutons. These results further demonstrate a considerable heterogeneity in the functional properties of the mossy fibre projection. PMID:22564530

Sherwood, John L; Amici, Mascia; Dargan, Sheila L; Culley, Georgia R; Fitzjohn, Stephen M; Jane, David E; Collingridge, Graham L; Lodge, David; Bortolotto, Zuner A

2012-04-27

283

Japanese fermented soybean food as the major determinant of the large geographic difference in circulating levels of vitamin K2  

Microsoft Academic Search

Increasing evidence indicates a significant role for vitamin K in bone metabolism and osteoporosis. In this study, we found a large geographic difference in serum vitamin K2 (menaquinone-7; MK-7) levels in postmenopausal women. Serum MK-7 concentrations were 5.26 ± 6.13 ng\\/mL (mean ± SD) in Japanese women in Tokyo, 1.22 ± 1.85 in Japanese women in Hiroshima, and 0.37 ±

Masao Kaneki; Stephen J. Hedges; Takayuki Hosoi; Saeko Fujiwara; Anthony Lyons; St. John Crean; Nobuhiko Ishida; Mamoru Nakagawa; Masahiro Takechi; Yoshihisa Sano; Yuzo Mizuno; Shinjiro Hoshino; Mariko Miyao; Satoshi Inoue; Kiyomi Horiki; Masataka Shiraki; Yasuyoshi Ouchi; Hajime Orimo

2001-01-01

284

Wavelet analysis of corneal endothelial electrical potential difference reveals cyclic operation of the secretory mechanism  

NASA Astrophysics Data System (ADS)

The corneal endothelium is a fluid-transporting epithelium. As other similar tissues, it displays an electrical potential of ˜1 mV (aqueous side negative) across the entire layer [transendothelial potential difference (TEPD)]. It appears that this electrical potential is mainly the result of the transport of anions across the cell layer (from stroma to aqueous). There is substantial evidence that the TEPD is related linearly to fluid transport; hence, under proper conditions, its measure could serve as a measure of fluid transport. Furthermore, the TEPD is not steady; instead, it displays a spectrum of frequency components (0-15 Hz) recognized recently using Fourier transforms. Such frequency components appear due to charge-separating (electrogenic) processes mediated by epithelial plasma membrane proteins (both ionic channels and ionic cotransporters). In particular, the endothelial TEPD oscillations of the highest amplitude (1-2 Hz) were linked to the operation of so-called sodium bicarbonate cotransporters. However, no time localization of that activity could be obtained with the Fourier methodology utilized. For that reason we now characterize the TEPD using wavelet analysis with the aim to localize in time the variations in TEPD. We find that the mentioned high-amplitude oscillatory components of the TEPD appear cyclically during the several hours that an endothelial preparation survives in vitro. They have a period of 4.6 ± 0.4 s on average (n=4). The wavelet power value at the peak of such oscillations is 1.5 ± 0.1 mV2 Hz on average (n = 4), and is remarkably narrow in its distribution.

Cacace, V. I.; Montalbetti, N.; Kusnier, C.; Gomez, M. P.; Fischbarg, J.

2011-09-01

285

Transglucosylation potential of six sucrose phosphorylases toward different classes of acceptors.  

PubMed

In this study, the transglucosylation potential of six sucrose phosphorylase (SP) enzymes has been compared using eighty putative acceptors from different structural classes. To increase the solubility of hydrophobic acceptors, the addition of various co-solvents was first evaluated. All enzymes were found to retain at least 50% of their activity in 25% dimethylsulfoxide, with the enzymes from Bifidobacterium adolescentis and Streptococcus mutans being the most stable. Screening of the enzymes' specificity then revealed that the vast majority of acceptors are transglucosylated very slowly by SP, at a rate that is comparable to the contaminating hydrolytic reaction. The enzyme from S. mutans displayed the narrowest acceptor specificity and the one from Leuconostoc mesenteroides NRRL B1355 the broadest. However, high activity could only be detected on l-sorbose and l-arabinose, besides the native acceptors d-fructose and phosphate. Improving the affinity for alternative acceptors by means of enzyme engineering will, therefore, be a major challenge for the commercial exploitation of the transglucosylation potential of sucrose phosphorylase. PMID:21798524

Aerts, Dirk; Verhaeghe, Tom F; Roman, Bart I; Stevens, Christian V; Desmet, Tom; Soetaert, Wim

2011-06-24

286

Kinetic and geometric isotope effects originating from different adsorption potential energy surfaces: Cyclohexane on Rh(111)  

NASA Astrophysics Data System (ADS)

Novel isotope effects were observed in desorption kinetics and adsorption geometry of cyclohexane on Rh(111) by the use of infrared reflection absorption spectroscopy, temperature programmed desorption, photoelectron spectroscopy, and spot-profile-analysis low energy electron diffraction. The desorption energy of deuterated cyclohexane (C6D12) is lower than that of C6H12. In addition, the work function change by adsorbed C6D12 is smaller than that by adsorbed C6H12. These results indicate that C6D12 has a shallower adsorption potential than C6H12 (vertical geometric isotope effect). The lateral geometric isotope effect was also observed in the two-dimensional cyclohexane superstructures as a result of the different repulsive interaction between interfacial dipoles. The observed isotope effects should be ascribed to the quantum nature of hydrogen involved in the C-H...metal interaction.

Koitaya, Takanori; Shimizu, Sumera; Mukai, Kozo; Yoshimoto, Shinya; Yoshinobu, Jun

2012-06-01

287

Differences between synaptic plasticity thresholds result in new timing rules for maximizing long-term potentiation.  

PubMed

The fundamental observation that the temporal spacing of learning episodes plays a critical role in the efficiency of memory encoding has had little effect on either research on long-term potentiation (LTP) or efforts to develop cognitive enhancers. Here we review recent findings describing a spaced trials phenomenon for LTP that appears to be related to recent evidence that plasticity thresholds differ between synapses in the adult hippocampus. Results of tests with one memory enhancing drug suggest that the compound potently facilitates LTP via effects on 'high threshold' synapses and thus alters the temporally extended timing rules. Possible implications of these results for our understanding of LTP substrates, neurobiological contributors to the distributed practice effect, and the consequences of memory enhancement are discussed. This article is part of a Special Issue entitled 'Cognitive Enhancers'. PMID:22820276

Lynch, Gary; Kramár, Enikö A; Babayan, Alex H; Rumbaugh, Gavin; Gall, Christine M

2012-07-20

288

Effects of sucrose concentration on the developmental potential of human frozen-thawed oocytes at different stages of maturity  

Microsoft Academic Search

BACKGROUD: Success of human oocyte cryopreservation depends on multiple cryobiological factors that could influence the developmental potential of the oocytes. The objective of this study was to examine the effects of different sucrose concentrations on the developmental potential of human frozen- thawed oocytes at different maturity stages. METHODS: A total of 355 oocytes collected from small follicles were randomly divided

Z. J. Chen; M. Li; Y. Li; L. X. Zhao; R. Tang; Y. Sheng; X. Gao; C. H. Chang

2004-01-01

289

Simulated environmental criticalities affect transglutaminase of Malus and Corylus pollens having different allergenic potential.  

PubMed

Increases in temperature and air pollution influence pollen allergenicity, which is responsible for the dramatic raise in respiratory allergies. To clarify possible underlying mechanisms, an anemophilous pollen (hazel, Corylus avellana), known to be allergenic, and an entomophilous one (apple, Malus domestica), the allergenicity of which was not known, were analysed. The presence also in apple pollen of known fruit allergens and their immunorecognition by serum of an allergic patient were preliminary ascertained, resulting also apple pollen potentially allergenic. Pollens were subjected to simulated stressful conditions, provided by changes in temperature, humidity, and copper and acid rain pollution. In the two pollens exposed to environmental criticalities, viability and germination were negatively affected and different transglutaminase (TGase) gel bands were differently immunodetected with the polyclonal antibody AtPng1p. The enzyme activity increased under stressful treatments and, along with its products, was found to be released outside the pollen with externalisation of TGase being predominant in C. avellana, whose grain presents a different cell wall composition with respect to that of M. domestica. A recombinant plant TGase (AtPng1p) stimulated the secreted phospholipase A(2) (sPLA(2)) activity, that in vivo is present in human mucosa and is involved in inflammation. Similarly, stressed pollen, hazel pollen being the most efficient, stimulated to very different extent sPLA(2) activity and putrescine conjugation to sPLA(2). We propose that externalised pollen TGase could be one of the mediators of pollen allergenicity, especially under environmental stress induced by climate changes. PMID:21847612

Iorio, Rosa Anna; Di Sandro, Alessia; Paris, Roberta; Pagliarani, Giulia; Tartarini, Stefano; Ricci, Giampaolo; Serafini-Fracassini, Donatella; Verderio, Elisabetta; Del Duca, Stefano

2011-08-17

290

Proficiency Differences in Syntactic Processing of Monolingual Native Speakers Indexed by Event-related Potentials  

PubMed Central

While anecdotally there appear to be differences in the way native speakers use and comprehend their native language, most empirical investigations of language processing study university students and none have studied differences in language proficiency which may be independent of resource limitations such as working memory span. We examined differences in language proficiency in adult monolingual native speakers of English using an event-related potential (ERP) paradigm. ERPs were recorded to insertion phrase structure violations in naturally spoken English sentences. Participants recruited from a wide spectrum of society were given standardized measures of English language proficiency, and two complementary ERP analyses were performed. In between-groups analyses, participants were divided, based on standardized proficiency scores, into Lower Proficiency (LP) and Higher Proficiency (HP) groups. Compared to LP participants, HP participants showed an early anterior negativity that was more focal, both spatially and temporally, and a larger and more widely distributed positivity (P600) to violations. In correlational analyses, we utilized a wide spectrum of proficiency scores to examine the degree to which individual proficiency scores correlated with individual neural responses to syntactic violations in regions and time windows identified in the between-group analyses. This approach also employed partial correlation analyses to control for possible confounding variables. These analyses provided evidence for the effects of proficiency that converged with the between-groups analyses. These results suggest that adult monolingual native speakers of English who vary in language proficiency differ in the recruitment of syntactic processes that are hypothesized to be at least in part automatic as well as of those thought to be more controlled. These results also suggest that in order to fully characterize neural organization for language in native speakers it is necessary to include participants of varying proficiency.

Pakulak, Eric; Neville, Helen J.

2010-01-01

291

Mechanism of milk secretion: milk composition in relation to potential difference across the mammary epithelium.  

PubMed

1. In conscious lactating goats a significant correlation was found between blood-milk potential difference (p.d.) and milk [lactose] such that in goats with a lower milk [lactose], milk was more negative with respect to blood.2. When mannose was substituted for glucose in the substrate mixture of isolated perfused goat mammary glands, milk yield and milk [lactose] fell while milk [Na] and [K] increased; in parallel experiments the blood-milk p.d. changed such that milk became more negative with respect to blood. These changes were reversed following the addition of glucose.3. When milk was made hypertonic by the addition of hyperosmotic sucrose or lactose solutions, water entered milk osmotically and milk became electrically less negative or even positive with respect to blood in goats, cows and guinea-pigs.4. No effect on p.d. was apparent following the addition of isosmotic sucrose to milk in goats.5. When milk was held in the teat of goats by a pneumatic cuff around the base of the teat, no effect on p.d. was apparent when hyperosmotic sucrose was introduced into this teat pouch.6. It is suggested that waterflow-induced potentials (the streaming potential and the transport number effect) can be induced across the mammary epithelium.7. In goats exogenous oxytocin lowered milk [lactose] and blood-milk p.d. became less negative with respect to blood.8. In non-lactating and mastitic glands of goats the blood-milk p.d. was within 0.5-2.5 mV of zero.9. The effects of oxytocin, and the low p.d. in non-lactating and mastitic glands, are compatible with the view that in such circumstances there is a paracellular pathway across the mammary epithelium which partially short-circuits the two sides.10. It is suggested that, with water being drawn osmotically into milk to dilute newly formed lactose, waterflow-induced potentials may be responsible for establishing the normal p.d. across the apical membrane of the secretary cell, thereby keeping milk [K] and [Na] lower than in intracellular fluid. PMID:903903

Peaker, M

1977-09-01

292

Potential effects of climate change on the water level, flora and macro-fauna of a large neotropical wetland.  

PubMed

Possible consequences of climate change in one of the world's largest wetlands (Ibera, Argentina) were analysed using a multi-scale approach. Climate projections coupled to hydrological models were used to analyse variability in wetland water level throughout the current century. Two potential scenarios of greenhouse gas emissions were explored, both resulting in an increase in the inter-annual fluctuations of the water level. In the scenario with higher emissions, projections also showed a long-term negative trend in water-level. To explore the possible response of biota to such water-level changes, species-area relationships of flora and aerial censuses of macro-fauna were analysed during an extraordinary dry period. Plant species richness at the basin scale was found to be highly resistant to hydrological changes, as the large dimension of the wetland acts to buffer against the water-level variations. However, local diversity decreased significantly with low water levels, leading to the loss of ecosystem resilience to additional stressors. The analysis of macro-fauna populations suggested that wetland provides refuge, in low water periods, for the animals with high dispersal ability (aquatic and migratory birds). On the contrary, the abundance of animals with low dispersal ability (mainly herbivorous species) was negatively impacted in low water periods, probably because they are required to search for alternative resources beyond the wetland borders. This period of resource scarcity was also related to increased mortality of large mammals (e.g. marsh deer) around water bodies with high anthropogenic enrichment and cyanobacteria dominance. The synergy between recurrent climatic fluctuations and additional stressors (i.e. biological invasions, eutrophication) presents an important challenge to the conservation of neotropical wetlands in the coming decades. PMID:23874446

Úbeda, Bárbara; Di Giacomo, Adrian S; Neiff, Juan José; Loiselle, Steven A; Poi, Alicia S Guadalupe; Gálvez, José Ángel; Casco, Silvina; Cózar, Andrés

2013-07-09

293

Complete tumor encapsulation on magnetic resonance imaging: a potentially useful imaging biomarker for better survival in solitary large hepatocellular carcinoma.  

PubMed

The aim of this study was to determine the prognostic value of complete tumor encapsulation as visualized on magnetic resonance imaging (MRI) in patients with a solitary large hepatocellular carcinoma (HCC) beyond the Milan criteria for liver transplantation (LT). Between December 2000 and March 2011, 57 patients who had a solitary HCC exceeding 5 cm in diameter at the time of initial MRI before any treatment were identified. MRI images of the patients were independently reviewed by 2 experienced readers for the presence of complete tumoral encapsulation. The medical records of the patients were reviewed for an outcome analysis. Thirty of the 57 patients had completely encapsulated HCC according to MRI. There was excellent interobserver agreement between the 2 readers for the assessment of complete encapsulation (?=0.86). Overall survival was significantly longer for patients with completely encapsulated HCC versus patients with incompletely or nonencapsulated tumors (P<0.001), and this included a subanalysis of 33 patients who received locoregional treatment (LRT; P=0.04). The presence of complete encapsulation was a strong predictor for survival in these patients according to both univariate [hazard ratio (HR)=0.24, 95% confidence interval (CI)=0.12-0.52, P<0.001] and multivariate analyses (HR=0.25, 95% CI=0.07-0.85, P=0.03). The rates of down-staging (P<0.001) and eventual LT (P=0.02) after LRT were also significantly higher in the patients with completely encapsulated tumors. In conclusion, complete tumor encapsulation on MRI is a potentially useful predictor for favorable biology in patients with a solitary large HCC. This new imaging biomarker may have a role in treatment selection for patients whose tumors exceed the Milan criteria size limits. PMID:23280814

Lu, David S; Siripongsakun, Surachate; Kyong Lee, Jeong; Wei, Sindy H; Cheng, Phillip M; Sabounchi, Saman; Lee, Jong Seok; Raman, Steven; Tong, Myron J; Busuttil, Ronald W; Sayre, James

2013-03-01

294

Electromagnetic phase differences in the coherent backscattering enhancement mechanism for random media consisting of large nontransparent spheres.  

PubMed

Phase curves of intensity are calculated for light scattering in media randomly packed with large nontransparent spheres (x=125), the surfaces of which reflect according to the Fresnel equations. We consider three values of refractive index: m = 0.73 + i5.93 (metal Al), 1.6 + i1.72 (metal Fe), and 1.5 + i0.1 (black glass). We use a Monte Carlo ray-tracing approach. Different kinds of electromagnetic phase differences of reciprocal trajectories are investigated for the second and third orders of scattering; the highest orders give comparatively small contributions due to the backward-scattering indicatrix of large nontransparent spheres. We find that the main electromagnetic phase difference between the direct and time-reversal (reciprocal) trajectories is the outer phase difference that depends only on the relative positions of the first and last points of the ray reflections and the phase angle. The inner phase difference is connected with the changing path length of the ray inside the medium. This depends on the particle size and the phase angle that is the angle between the source and receiver from the scatterer, i.e., 180 degrees minus the scattering angle. The inner phase difference can give oscillations in the phase curve consisting of second-order components if the medium consists of strictly monodisperse spheres. Usually the coherent backscattering enhancement is calculated ignoring the shadow-hiding effect. We show that accounting for the shadowing of the reciprocal trajectory is important for the formation of the backscattering effect. The third-order scattering surge is a superposition of wide and narrow opposition spikes that correspond to two different types of scattering trajectories, closed and opened ones. The first type is due to scattering by two particles; the second one corresponds to scattering by three particles. PMID:17334449

Stankevich, Dmitriy; Istomina, Larissa; Shkuratov, Yuriy; Videen, Gorden

2007-03-20

295

Uniform ac field in anisotropic bar and alternating current potential difference stress measurement  

NASA Astrophysics Data System (ADS)

Some theoretical and experimental studies are presented on magnetostrictive anisotropy (stress induced anisotropy) in a long circular steel bar. An explicit analytical solution to the problem of uniform axial alternating current (ac) distribution in a cylindrical bar which retains magnetic and electrical anisotropy was established. By relating the stress level to the amount of magnetic anisotropy in the material, an electromagnetic stress model was then developed for cylindrical bars under uniaxial stress using the analytical solution. For the application of this model, experimental stress measurements on mild steel bars with different radii were conducted based on the alternating current potential difference (ACPD) technique. During the test, a form of alternating current field measurement (ACFM) instrumentation, known as the ACFM crack microgauge, was used to inject a uniform ac current into the steel bars and to measure the electrical field on the bar surface. The ACPD stress measurement results showed that the theoretical stress model could predict the stress values with the calibration of a magnetic anisotropic parameter.

Zhou, Jianwei; Chen, Kaisheng; Dover, William D.

1999-07-01

296

Interplay of optical potential and condensate properties for bosons in different optical lattice geometries  

NASA Astrophysics Data System (ADS)

Motivated by the availability of optical lattices with tunable geometries in experiments, we compute different physical properties such as condensate fraction, fluctuation and depletion of the condensate density and quasi-particle velocity as a function of the interparticle interaction strength for bosons in different 2D optical potentials that correspond to square, triangular and honeycomb geometries. Our results demonstrate an interplay of these features with that of the coordination number and underlying lattice geometries. A triangular lattice, which has a coordination number z = 6, shows larger condensate fraction and fluctuation of the condensate density, along with a low depletion of the ground state occupancy. The other candidates, namely the square lattice (z = 4) and honeycomb lattice (z = 3) occupy second and third places, respectively, with regard to these properties. The quasi-particle velocities for these geometries follow a similar pattern as that of the condensate fraction data. The observations are explained by the behaviour of the low-energy quasi-particle density of states. Finally, to make the role of lattice geometry obvious, we include a discussion on a kagome lattice, which in spite of having the same coordination number as that of a square lattice, i.e. z = 4, yields a significantly low condensate fraction than that of the square lattice for all values of the interacting strength.

Barman, Apurba; Basu, Saurabh

2012-05-01

297

Different Electrostatic Potentials Define ETGE and DLG Motifs as Hinge and Latch in Oxidative Stress Response?  

PubMed Central

Nrf2 is the regulator of the oxidative/electrophilic stress response. Its turnover is maintained by Keap1-mediated proteasomal degradation via a two-site substrate recognition mechanism in which two Nrf2-Keap1 binding sites form a hinge and latch. The E3 ligase adaptor Keap1 recognizes Nrf2 through its conserved ETGE and DLG motifs. In this study, we examined how the ETGE and DLG motifs bind to Keap1 in a very similar fashion but with different binding affinities by comparing the crystal complex of a Keap1-DC domain-DLG peptide with that of a Keap1-DC domain-ETGE peptide. We found that these two motifs interact with the same basic surface of either Keap1-DC domain of the Keap1 homodimer. The DLG motif works to correctly position the lysines within the Nrf2 Neh2 domain for efficient ubiquitination. Together with the results from calorimetric and functional studies, we conclude that different electrostatic potentials primarily define the ETGE and DLG motifs as a hinge and latch that senses the oxidative/electrophilic stress.

Tong, Kit I.; Padmanabhan, Balasundaram; Kobayashi, Akira; Shang, Chengwei; Hirotsu, Yosuke; Yokoyama, Shigeyuki; Yamamoto, Masayuki

2007-01-01

298

Differences in female individual reproductive potential among three stocks of winter flounder, Pseudopleuronectes americanus  

NASA Astrophysics Data System (ADS)

Potential annual fecundity (PAF) and skipped spawning of winter flounder, Pseudopleuronectes americanus, were compared among the three stocks in United States waters and between two spawning seasons. Winter flounder have group-synchronous oocyte development and determinate fecundity. These characteristics enable estimation of PAF just prior to spawning by enumeration of the late-vitellogenic cohort of oocytes, in this case employing the autodiametric method. There was a low level of down-regulation, which was limited to fish in the earlier stages of vitellogenesis. Estimates of PAF increased substantially with female size and age, ranging from < 0.5 million to > 5 million eggs per female. Fecundity at size decreased with increasing latitude. On average, fish from the Southern New England (SNE) stock had the highest individual fecundities at length and Gulf of Maine (GOM) the lowest, but differences varied among the years. Fecundity at length of fish from Georges Bank (GB) was intermediate to these two stocks and displayed less variability at size; however, GB fish grow faster so they had the highest relative fecundity at age. Skipped spawning also exhibited geographic differences; it was infrequent (< 2%) overall, but observed in the two coastal stocks (GOM more than SNE) in both years and was not observed in the GB stock. Fecundity at size between the two years was more similar for SNE fish, but all three stocks were synchronized with higher PAF in 2011 than 2010. Comparisons to previously published estimates suggest fecundity is highly variable in this species. Overall, different rates of reproductive productivity exist among individuals of the three stocks.

McElroy, W. David; Wuenschel, Mark J.; Press, Yvonna K.; Towle, Emilee K.; McBride, Richard S.

2013-01-01

299

Hemispheric Lateralization of Event-Related Brain Potentials in Different Processing Phases during Unimanual Finger Movements  

PubMed Central

Previous functional MRI and brain electrophysiology studies have studied the left-right differences during the tapping tasks and found that the activation of left hemisphere was more significant than that of right hemisphere. In this study, we wanted to delineate this lateralization phenomenon not only in the execution phase but also in other processing phases, such as early visual, pre-executive and post-executive phases. We have designed a finger-tapping task to delineate the left-right differences of event related potentials (ERPs) to right finger movement in sixteen right handed college students. The mean amplitudes of ERPs were analyzed to examine the left-right dominance of cortical activity in the phase of early visual process (75-120ms), pre-execution (175-260ms), execution (310-420ms) and post-execution (420-620ms). In the execution phase, ERPs at the left electrodes were significantly more pronounced than those at the right electrodes (F3 > F4, C3 > C4, P3 > P4, O1 > O2) under the situation without comparing the central electrodes (Fz, Cz, Pz, and Oz). No difference was found between left and right electrodes in other three phases except the C3 electrode still showed more dominant than C4 in the pre- and post-execution phase. In conclusion, the phenomenon of brain lateralization occur major in the execution phase. The central area also showed the lateralization in the pre- and post-execution to demonstrate its unique lateralized contributions to unilateral simple finger movements.

Meng, Ling-Fu; Lu, Chiu-Ping; Li, Yi-Wen

2008-01-01

300

Experimental Investigation on the difference between the plasma potential and the floating potential of the cylindrical probe in an inductively coupled plasmas  

NASA Astrophysics Data System (ADS)

The difference between plasma potential (Vp) and floating potential (Vf) is of interest because it directly relate to ion energy inciding to a floating wall or silicon wafer. F. F. Chen et. al. [F.F. Chen and D. Arnush, Phys. Plasmas, 8, 5051(2001)] show that the potential difference between them in cylindrical probe is a function of plasma density. However, F. F. Chen et. al. assumed that the electron energy distribution function(EEDF) is Maxwellian and the EEDF is constant against RF powers. To investigate the effect of the EEDF on the potential difference in inductively coupled plasma, the electron energy distribution functions (EEDF) are measured at low pressure (2 and 10mTorr). The EEDFs are bi-Maxwellian EEDFs with two temperatures below the ionization energy of the electrons. It is found that the difference (Vp - Vf) is not constant but a strong function of plasma density as Chen¡¯s theoretical results and the theoretical potential difference lies within those calculated by high electron temperature and low electron temperature. The results of our experiment agree qualitatively with F. F. Chen's theory

Lee, Wonki; Oh, Sejin; Jang, S. H.; Choi, I. J.; Chinwook, Chinwook

2004-09-01

301

Denitrification potential of different land-use types in an agricultural watershed, lower Mississippi valley  

USGS Publications Warehouse

Expansion of agricultural land and excessive nitrogen (N) fertilizer use in the Mississippi River watershed has resulted in a three-fold increase in the nitrate load of the river since the early 1950s. One way to reduce this nitrate load is to restore wetlands at suitable locations between croplands and receiving waters to remove run-off nitrate through denitrification. This research investigated denitrification potential (DP) of different land uses and its controlling factors in an agricultural watershed in the lower Mississippi valley (LMV) to help identify sites with high DP for reducing run-off nitrate. Soil samples collected from seven land-use types of an agricultural watershed during spring, summer, fall and winter were incubated in the laboratory for DP determination. Low-elevation clay soils in wetlands exhibited 6.3 and 2.5 times greater DP compared to high-elevation silt loam and low-elevation clay soils in croplands, respectively. DP of vegetated-ditches was 1.3 and 4.2 times that of un-vegetated ditches and cultivated soils, respectively. Soil carbon and nitrogen availability, bulk density, and soil moisture significantly affected DP. These factors were significantly influenced in turn by landscape position and land-use type of the watershed. It is evident from these results that low-elevation, fine-textured soils under natural wetlands are the best locations for mediating nitrate loss from agricultural watersheds in the LMV. Landscape position and land-use types can be used as indices for the assessment/modeling of denitrification potential and identification of sites for restoration for nitrate removal in agricultural watersheds. ?? 2006 Elsevier B.V. All rights reserved.

Ullah, S.; Faulkner, S. P.

2006-01-01

302

Interactions between oestrogen and the renin angiotensin system - potential mechanisms for gender differences in Alzheimer's disease  

PubMed Central

Interactions between oestrogen and the renin angiotensin system (RAS) are reviewed and explored from the perspective where these interactions may modulate risk of developing Alzheimer’s disease (AD). AD is more prevalent in women than men, partly attributed to women’s increased life expectancy; however underlying vascular differences may also contribute to AD risk. The RAS is a key regulator of blood pressure (BP). Pharmacological inhibition of angiotensin converting enzyme (ACE) and blockade of angiotensin II type 1 receptors (AT1R) are widely used to treat hypertension. Variation in components of the RAS such as ACE, neprilysin (NEP) and AT1R have been reported in AD, some of which may also directly alter AD neuropathology with changes in amyloid beta (A?) levels, cognitive decline and neuroinflammation. Recently, RAS inhibiting drugs have been shown to attenuate the incidence, progression and pathology of AD. Oestrogen is also thought to prevent hypertension by reducing the vasoconstrictive actions of the RAS. Reduced oestrogen levels in women during the menopausal transition may therefore increase their risk of hypertension and/or RAS-mediated changes to cerebrovascular or AD pathology. Specifically, oestrogen prevents the production and action of angiotensin II (Ang II), thought to exert harmful effects of the RAS in both hypertension and AD, while also potentially facilitating RAS-mediated A? degradation. These oestrogen-RAS interactions may partly explain current conflicting findings regarding oestrogen depletion and hormone therapy with respect to AD risk. Clinical trials targeting either the RAS or oestrogen systems for AD prevention and treatment should perhaps give closer attention to key biochemical components of these pathways as potential confounders to primary and secondary outcome measures.

O'Hagan, Thomas Simon; Wharton, Whitney; Kehoe, Patrick Gavin

2012-01-01

303

Analysis of the nuclear potential for heavy-ion systems through large-angle quasi-elastic scattering  

NASA Astrophysics Data System (ADS)

A study on the surface diffuseness parameter of the nuclear potential for the reactions of 208Pb with 48Ti, 54Cr, 56Fe, 64Ni, and 70Zn is performed using large-angle quasi-elastic scattering experimental data. Diffuseness parameters that are considerably lower than the standard value of around 0.63 fm are required in order to fit the experimental data at deep sub-barrier energies, except for the 54Cr+208Pb system, where the required diffuseness parameter is in satisfactory agreement with (but still lower than) the standard value. Furthermore, when the energies of the experimental data used in the fittings are increased from the deep sub-barrier region to the energies closer to the Coulomb barrier height, the best fitted diffuseness parameters also increase. The increase in the obtained diffuseness parameters as the energies are increased also seems to have a possible tendency to be a function of the charge product of the target and projectile nuclei. We find that the phenomenon of threshold anomaly might explain our findings here. The increase in the diffuseness parameters could also due to dynamical effects, for example, due to neutron movements.

Inche Ibrahim, M. L.; Zamrun, Muhammad; Kassim, Hasan Abu

2013-02-01

304

Estimating the Potential Impacts of Large Mesopredators on Benthic Resources: Integrative Assessment of Spotted Eagle Ray Foraging Ecology in Bermuda  

PubMed Central

Declines of large sharks and subsequent release of elasmobranch mesopredators (smaller sharks and rays) may pose problems for marine fisheries management as some mesopredators consume exploitable shellfish species. The spotted eagle ray (Aetobatus narinari) is the most abundant inshore elasmobranch in subtropical Bermuda, but its predatory role remains unexamined despite suspected abundance increases and its hypothesized specialization for mollusks. We utilized a combination of acoustic telemetry, benthic invertebrate sampling, gut content analysis and manipulative experiments to assess the impact of spotted eagle rays on Bermudian shellfish resources. Residency and distribution of adult spotted eagle rays was monitored over two consecutive summers in Harrington Sound (HS), an enclosed inshore lagoon that has historically supported multiple recreational and commercial shellfish species. Telemetered rays exhibited variable fidelity (depending on sex) to HS, though generally selected regions that supported relatively high densities of potential mollusk prey. Gut content analysis from rays collected in HS revealed a diet of mainly bivalves and a few gastropods, with calico clam (Macrocallista maculata) representing the most important prey item. Manipulative field and mesocosm experiments with calico clams suggested that rays selected prey patches based on density, though there was no evidence of rays depleting clam patches to extirpation. Overall, spotted eagle rays had modest impacts on local shellfish populations at current population levels, suggesting a reduced role in transmitting cascading effects from apex predator loss. However, due to the strong degree of coupling between rays and multiple protected mollusks in HS, ecosystem-based management that accounts for ray predation should be adopted.

Ajemian, Matthew J.; Powers, Sean P.; Murdoch, Thaddeus J. T.

2012-01-01

305

An investigation into the role that a transverse magnetic field plays in the formation of large anode sheath potentials  

SciTech Connect

A 9.25 A low-pressure (45{endash}55 mTorr) hollow cathode arc discharge has been used to simulate plasma processes that occur at the anode of magnetoplasmadynamic accelerators used for space propulsion applications. The interest in the near-anode region is related to findings of past research, which indicate that large anode sheath potentials can drive as much as 70{percent} of the input electrical power into the anode, thus degrading thrust efficiency. Presented here are results that essentially characterize the behavior of the near-anode plasma as a function of a transverse magnetic field. Plasma diagnostics included single Langmuir probe techniques, emission spectroscopy, and water calorimetry for anode heat flux measurements. Phenomenological arguments based on measurements taken suggest that observed changes in anode fall voltage are related to variations in the measured local electron number density as the magnetic field is varied. This behavior is attributed to the variations in the measured ionization rate, which is shown to be a nonlinear function of transverse magnetic field. {copyright} {ital 1996 American Institute of Physics.}

Foster, J.E.; Gallimore, A.D. [The Plasmadynamics and Electric Propulsion Laboratory, The University of Michigan, Ann Arbor, Michigan 48109 (United States)

1996-11-01

306

A Large-Scale Investigation of Lateralization in Cortical Anatomy and Word Reading: Are There Sex Differences?  

PubMed Central

Although left hemisphere language specialization is one of the most widely reported findings in human neuropsychology, some studies have found evidence for more bilateral language organization in women. We report findings of a large scale, multi-task investigation of sex differences in both structural asymmetries and lateralization of word reading. Two hundred participants were tested in eight divided visual field lexical tasks, and each received a structural MRI scan. We examined whether there was evidence for sex differences in overall measures of neuroanatomical and behavioral lateralization, in specific language tasks and brain regions, and in variation in asymmetry within and across tasks and brain regions. There was very little evidence for sex differences on any behavioral measure. The few indications of sex differences in the current report accounted for 2% or less of the individual variation in asymmetry and could not be replicated in independent subsamples. No sex differences were observed in the asymmetry of structures in Broca’s and Wernicke’s area such as pars triangularis, pars opercularis, the planum temporale, planum parietale, or Heschl’s gyrus. There were also no sex differences in the variability of neuroanatomical asymmetries within or between brain regions. However, a significant relationship between planum temporale and behavioral asymmetry was restricted to men.

Chiarello, Christine; Welcome, Suzanne E.; Halderman, Laura K.; Towler, Stephen; Julagay, Janelle; Otto, Ronald; Leonard, Christiana M.

2011-01-01

307

Potential change during intercalation of sulfuric acid in host carbons with different textures  

Microsoft Academic Search

From the electric potential changes, the intercalation reaction of sulfuric acid in graphite was divided into two elemental processes: the charging process of the interface between graphite layer and intercalated sulfuric acid in pure stages, which corresponded to a steep increase in potential, and the stage transformation process caused by further intercalation, which showed a plateau on the potential change

Norio Iwashita; Hiroshi Shioyama; Michio Inagaki

1995-01-01

308

Differences in evoked potentials during the active processing of sound location and motion.  

PubMed

Difference in the processing of motion and static sounds in the human cortex was studied by electroencephalography with subjects performing an active discrimination task. Sound bursts were presented in the acoustic free-field between 47° to the left and 47° to the right under three different stimulus conditions: (i) static, (ii) leftward motion, and (iii) rightward motion. In an active oddball design, subject was asked to detect target stimuli which were randomly embedded within a stream of frequently occurring non-target events (i.e. 'standards') and rare non-target stimuli (i.e. 'deviants'). The respective acoustic stimuli were presented in blocks with each stimulus type presented in either of three stimulus conditions: as target, as non-target, or as standard. The analysis focussed on the event related potentials evoked by the different stimulus types under the respective standard condition. Same as in previous studies, all three different acoustic stimuli elicited the obligatory P1/N1/P2 complex in the range of 50-200 ms. However, comparisons of ERPs elicited by static stimuli and both kinds of motion stimuli yielded differences as early as ~100 ms after stimulus-onset, i.e. at the level of the exogenous N1 and P2 components. Differences in signal amplitudes were also found in a time window 300-400 ms ('d300-400 ms' component in 'motion-minus-static' difference wave). For motion stimuli, the N1 amplitudes were larger over the hemisphere contralateral to the origin of motion, while for static stimuli N1 amplitudes over both hemispheres were in the same range. Contrary to the N1 component, the ERP in the 'd300-400 ms' time period showed stronger responses over the hemisphere contralateral to motion termination, with the static stimuli again yielding equal bilateral amplitudes. For the P2 component a motion-specific effect with larger signal amplitudes over the left hemisphere was found compared to static stimuli. The presently documented N1 components comply with the results of previous studies on auditory space processing and suggest a contralateral dominance during the process of cortical integration of spatial acoustic information. Additionally, the cortical activity in the 'd300-400 ms' time period indicates, that in addition to the motion origin (as reflected by the N1) also the direction of motion (leftward/ rightward motion) or rather motion termination is cortically encoded. These electrophysiological results are in accordance with the 'snap shot' hypothesis, assuming that auditory motion processing is not based on a genuine motion-sensitive system, but rather on a comparison process of spatial positions of motion origin (onset) and motion termination (offset). Still, specificities of the present P2 component provides evidence for additional motion-specific processes possibly associated with the evaluation of motion-specific attributes, i.e. motion direction and/or velocity which is preponderant in the left hemisphere. PMID:23499852

Richter, Nicole; Schröger, Erich; Rübsamen, Rudolf

2013-03-14

309

Differences in rural and urban driver-injury severities in accidents involving large-trucks: an exploratory analysis.  

PubMed

This study explores the differences between urban and rural driver injuries (both passenger-vehicle and large-truck driver injuries) in accidents that involve large trucks (in excess of 10,000 pounds). Using 4 years of California accident data, and considering four driver-injury severity categories (no injury, complaint of pain, visible injury, and severe/fatal injury), a multinomial logit analysis of the data was conducted. Significant differences with respect to various risk factors including driver, vehicle, environmental, road geometry and traffic characteristics were found to exist between urban and rural models. For example, in rural accidents involving tractor-trailer combinations, the probability of drivers' injuries being severe/fatal increased about 26% relative to accidents involving single-unit trucks. In urban areas, this same probability increased nearly 700%. In accidents where alcohol or drug use was identified as being the primary cause of the accident, the probability of severe/fatal injury increased roughly 250% percent in rural areas and nearly 800% in urban areas. While many of the same variables were found to be significant in both rural and urban models (although often with quite different impact), there were 13 variables that significantly influenced driver-injury severity in rural but not urban areas, and 17 variables that significantly influenced driver-injury severity in urban but not rural areas. We speculate that the significant differences between rural and urban injury severities may be at least partially attributable to the different perceptual, cognitive and response demands placed on drivers in rural versus urban areas. PMID:15935320

Khorashadi, Ahmad; Niemeier, Debbie; Shankar, Venky; Mannering, Fred

2005-09-01

310

Protein and mRNA characterization in human colorectal carcinoma cell lines with different metastatic potentials.  

PubMed

Metastasis, the important characteristic of malignant tumors, is closely associated with a series of changes in the expressions of genes and proteins. In this study, we compared mRNA and protein expressions in a pair of human colorectal carcinoma cell lines named SW620 and SW480 with different metastatic potentials by suppression subtractive hybridization and 2-dimensional gel electrophoresis combined with the matrix-assisted laser desorption/ionization time-of-flight mass spectrometer. After suppression subtractive hybridization and differential screening, 24 differentially expressed gene fragments were obtained, including 9 known genes and 15 novel genes. Nine known genes, such as Cytochrome C, Oxidase II and III, Serum amyloid A, Mitotic Control Protein dis3, Eukaryotic Translation Initiation Factor 4A, function in the process of growth and differentiation, transcription, apoptosis, signal transduction. Six novel genes were found to locate in chromosome 5. Northern blot further confirmed the results. For protein analysis, 16 significantly different protein spots were detected using 2-dimensional gel electrophoresis and peptide mass fingerprinting analysis. The results were confirmed by Western blot. The peptide mass fingerprintings of spots were then compared with the NCBI and SWISS PROT database. The differentially expressed proteins included Galectin-1, Annexin A1, Casein kinase 2, Cytochrome c oxidase subunit VIb, S-100D calcium-binding protein, which may be involved in cell differentiation and proliferation, signal transduction, cell adhesion and migration, and tumor evasion of immune responses. An analysis of these genes and proteins reiterated much of our understanding of the metastatic process and also offered some identified targets without previously characterized functions, especially the novel metastasis associated genes, to be further investigated. Moreover, the results of the phenotypic function-related expression mapping analysis at the mRNA and protein level revealed obvious complementarities, providing important clues for further study of the molecular mechanism of metastasis, metastasis control and possible targets for cancer gene therapy. PMID:17882654

Liang, Li; Qu, Lijuan; Ding, Yanqing

2007-09-01

311

Mass flux through solid 4He induced by chemical potential differences  

NASA Astrophysics Data System (ADS)

The thermo-mechanical effect and also direct mass injection have been used to create chemical potential differences between two reservoirs of superfluid 4He connected to each other through superfluid-filled Vycor rods in series with solid hcp 4He. An increasing DC flux of atoms takes place through the solid-filled cell with decreasing temperature below asymp 600 mK That flux falls abruptly in the vicinity of 75-80 mK, but increases again at lower temperatures. These experiments, done in collaboration with M Ray, will be briefly reviewed as will our studies of the growth of solid 4He where it is seen that it is impossible to add density to a solid freshly made at 60 mK and samples freshly made near 60 mK do not allow mass flux, even when raised in temperature to 200 mK Solids created above asymp 300 mK and cooled to 60 mK accept added density and demonstrate finite mass flux. Relationships to theoretical work and other solid helium work will be briefly discussed.

Hallock, R. B.

2012-12-01

312

Event-related potentials findings differ between children and adults during arithmetic-fact retrieval.  

PubMed

Some cognitive abilities of arithmetical calculation depend on retrieval of arithmetic facts from long-term memory. Arithmetic-fact retrieval has been studied in adults through Event-Related Potentials (ERP) experiments. Such information in children, however, has been scarce. It has been reported that from the age of 9 years, children employ a memory retrieval strategy for solving simple multiplication problems. The present study compared arithmetical-fact retrieval in children and adults while they were being subjected to ERP recording. The subjects were asked to make judgments about solutions to simple multiplication problems. Both groups of participants displayed the so-called arithmetic N400 effect for incorrect solutions relative to correct solutions. Adults showed a posterior N400 effect, while children showed a widely distributed N400 effect. Children displayed a larger amplitude and longer latency arithmetic N400 component than adults; this observation could be due to children exerting greater effort involving more widespread cortical activation than adults to solve the experimental problems. The Late Positive Component (LPC), which follows the arithmetic N400 and has been described previously in adult subjects, was observed in the present adult subjects, but was present in children only for correct solutions. These results may indicate that, relative to adults, children showed slower memory retrieval and a different pattern of a verification mechanism for correct and incorrect solutions. PMID:19897015

Prieto-Corona, Belén; Rodríguez-Camacho, Mario; Silva-Pereyra, Juan; Marosi, Erzsébet; Fernández, Thalía; Guerrero, Vicente

2009-11-06

313

Ribotypes and virulence gene polymorphisms suggest three distinct Listeria monocytogenes lineages with differences in pathogenic potential.  

PubMed Central

A total of 133 Listeria monocytogenes isolates were characterized by ribotyping and allelic analysis of the virulence genes hly, actA, and inlA to uncover linkages between independent phylogenetic and specific virulence markers. PCR-restriction fragment length polymorphisms revealed 8 hly, 11 inl4, and 2 actA alleles. The combination of these virulence gene alleles and ribotype patterns separated L. monocytogenes into three distinct lineages. While distinct hly and inlA alleles were generally found to cluster into these three lineages, actA alleles segregated independently. These three phylogenetic lineages were confirmed when 22 partial actA DNA sequences were analyzed. The clinical history of the L. monocytogenes strains showed evidence for differences in pathogenic potential among the three lineages. Lineage I contains all strains isolated during epidemic outbreaks of listeriosis, while no human isolates were found in lineage III. Animal isolates were found in all three lineages. We found evidence that isolates from lineages I and III have a higher plaquing efficiency than lineage II strains in a cell culture assay. Strains from lineage III also seem to form larger plaques than strains from lineage II. A distinctive ribotype fragment and unique 16S rRNA gene sequences furthermore suggest that lineage III might represent a L. monocytogenes subspecies. None of the 20 human isolates available but 11% of our animal isolates were grouped in this lineage, indicating that strains in this lineage might have reduced virulence for humans.

Wiedmann, M; Bruce, J L; Keating, C; Johnson, A E; McDonough, P L; Batt, C A

1997-01-01

314

Antimicrobial potential of Ricinus communis leaf extracts in different solvents against pathogenic bacterial and fungal strains  

PubMed Central

Objective To investigate the in vitro antimicrobial activities of the leaf extract in different solvents viz., methanol, ethanol and water extracts of the selected plant Ricinus communis. Methods Agar well diffusion method and agar tube dilution method were carried out to perform the antibacterial and antifungal activity of methanol, ethanol and aqueous extracts. Results Methanol leaf extracts were found to be more active against Gram positive bacteria (Bacillus subtilis: ATCC 6059 and Staphylococcus aureus: ATCC 6538) as well as Gram negative bacteria (Pseudomonas aeruginosa: ATCC 7221 and Klebsiella pneumoniae) than ethanol and aqueous leaf extracts. Antifungal activity of methanol and aqueous leaf extracts were also carried out against selected fungal strains as Aspergillus fumigatus and Aspergillus flavus. Methanolic as well as aqueous leaf extracts of Ricinus communis were effective in inhibiting the fungal growth. Conclusions The efficient antibacterial and antifungal activity of Ricinus communis from the present investigation revealed that the methanol leaf extracts of the selected plant have significant potential to inhibit the growth of pathogenic bacterial and fungal strains than ethanol and aqueous leaf extracts.

Naz, Rabia; Bano, Asghari

2012-01-01

315

Physiological Effects of Two Different Postactivation Potentiation Training Loads on Power Profiles Generated During High Intensity Cycle Ergometer Exercise  

Microsoft Academic Search

The purpose of this study was to investigate whether postactivation potentiation (PAP) would have any effect on high intensity cycle ergometer performance. Two different squatting exercises of different loads were presented in a random fashion prior to ergometric exercise. Seven male rugby players volunteered to participate in the study. There were no significant differences observed between peak power output (PPO)

Sian Parry; Stuart Hancock; Matthew Shiells; Louis Passfield; Bruce Davies; Julien S. Baker

2008-01-01

316

Recruitment potential of two perennial grasses with different growth forms at a semiarid-arid transition zone  

Microsoft Academic Search

The objective of this study was to quantify differences in recruitment potential (seed production, seed presence in the soil) for two congeneric perennial grasses (Bouteloua gracilis, Bouteloua eriopoda (Poaceae)) that dominate adjacent arid and semiarid grassland biomes. It was hypothesized that these species have different recruitment strategies at the biome transition zone that are related to differences in their growth

DEBRA P. C. PETERS

2002-01-01

317

Investigation on the Plasma-Induced Emission Properties of Large Area Carbon Nanotube Array Cathodes with Different Morphologies  

PubMed Central

Large area well-aligned carbon nanotube (CNT) arrays with different morphologies were synthesized by using a chemical vapor deposition. The plasma-induced emission properties of CNT array cathodes with different morphologies were investigated. The ratio of CNT height to CNT-to-CNT distance has considerable effects on their plasma-induced emission properties. As the ratio increases, emission currents of CNT array cathodes decrease due to screening effects. Under the pulse electric field of about 6 V/?m, high-intensity electron beams of 170–180 A/cm2 were emitted from the surface plasma. The production mechanism of the high-intensity electron beams emitted from the CNT arrays was plasma-induced emission. Moreover, the distribution of the electron beams was in situ characterized by the light emission from the surface plasma.

2011-01-01

318

Auditory Evoked Potentials and Hand Preference in 6-Month-Old Infants: Possible Gender-Related Differences in Cerebral Organization  

Microsoft Academic Search

Normal 6-month-old infants (10 male and 10 female) were studied to determine if cortical auditory evoked potentials recorded to probe stimuli during verbal and musical stimulus presentation provided an index of cerebral functional organization. Furthermore, evoked potential left–right amplitude asymmetries were examined in relation to gender differences and hand-reaching preference in these infants. Six-month-old girls exhibited evoked potential amplitude asymmetries

Janet L. Shucard; David W. Shucard

1990-01-01

319

The molecular signature of mediastinal large B-cell lymphoma differs from that of other diffuse large B-cell lymphomas and shares features with classical Hodgkin lymphoma  

Microsoft Academic Search

Mediastinal large B-cell lymphoma (MLBCL) is a recently identified subtype of diffuse large B-cell lymphoma (DLBCL) that char- acteristically presents as localized tu- mors in young female patients. Although MLBCL has distinctive pathologic fea- tures, it clinically resembles the nodular sclerosis subtype of classical Hodgkin lymphoma (cHL). To elucidate the molecu- lar features of MLBCL, we compared the gene expression

Kerry J. Savage; Stefano Monti; Jeffery L. Kutok; Giorgio Cattoretti; Donna Neuberg; Laurence de Leval; Paul Kurtin; Paola Dal Cin; Christine Ladd; Friedrich Feuerhake; Ricardo C. T. Aguiar; Sigui Li; Gilles Salles; Francoise Berger; Wen Jing; Geraldine S. Pinkus; Thomas Habermann; Riccardo Dalla-Favera; Lee Harris; Jon C. Aster; Todd R. Golub; Margaret A. Shipp

2003-01-01

320

Differences of Circulating Inflammatory Markers between Large- and Small Vessel Disease in Patients with Acute Ischemic Stroke.  

PubMed

Background: The difference of inflammatory response between the pathogenesis of cerebral large- and small vessel disease after stroke remains unclear. In present study, we aim to determine the association of circulating inflammatory markers with different stroke subtype. Methods: 99 patients with non-cardioembolic stroke were divided into large artery atherosclerosis (LAA) and small-artery occlusion (SAO) according to TOAST classification. A panel of plasma inflammatory markers including leukocyte, lymphocyte, CRP, fibrinogen, D-dimer, CD40L, IFN-?, IL-1?, IL-1?, IL-6, IL-8, IL-17 and TNF-? were measured within 72 hours following cerebral ischemia. The relation of their levels in plasma with stroke subtype was further studied. All statistical data analysis was performed by SPSS 17.0 software. Results: We found that only CRP were closely associated with stroke subtype (p<0.05). Compared to SAO subgroup, the plasma levels of CRP was higher in LAA subgroup (p<0.05). The predictive efficiency of CRP more than 3.2 for LAA was 85.7% sensitivity. The influencing factor of CRP includes IL-6, lymphocyte, fibrinogen and D-dimer. Conclusion: LAA had a stronger activation of inflammation than SAO in the pathogenesis, which was associated with the changes of CRP. PMID:23983602

Zeng, Lili; He, Xiaosong; Liu, Jianrong; Wang, Ling; Weng, Suiqing; Wang, Yongting; Chen, Shengdi; Yang, Guo-Yuan

2013-08-22

321

Estimating the potential impacts of large mesopredators on benthic resources: integrative assessment of spotted eagle ray foraging ecology in Bermuda.  

PubMed

Declines of large sharks and subsequent release of elasmobranch mesopredators (smaller sharks and rays) may pose problems for marine fisheries management as some mesopredators consume exploitable shellfish species. The spotted eagle ray (Aetobatus narinari) is the most abundant inshore elasmobranch in subtropical Bermuda, but its predatory role remains unexamined despite suspected abundance increases and its hypothesized specialization for mollusks. We utilized a combination of acoustic telemetry, benthic invertebrate sampling, gut content analysis and manipulative experiments to assess the impact of spotted eagle rays on Bermudian shellfish resources. Residency and distribution of adult spotted eagle rays was monitored over two consecutive summers in Harrington Sound (HS), an enclosed inshore lagoon that has historically supported multiple recreational and commercial shellfish species. Telemetered rays exhibited variable fidelity (depending on sex) to HS, though generally selected regions that supported relatively high densities of potential mollusk prey. Gut content analysis from rays collected in HS revealed a diet of mainly bivalves and a few gastropods, with calico clam (Macrocallista maculata) representing the most important prey item. Manipulative field and mesocosm experiments with calico clams suggested that rays selected prey patches based on density, though there was no evidence of rays depleting clam patches to extirpation. Overall, spotted eagle rays had modest impacts on local shellfish populations at current population levels, suggesting a reduced role in transmitting cascading effects from apex predator loss. However, due to the strong degree of coupling between rays and multiple protected mollusks in HS, ecosystem-based management that accounts for ray predation should be adopted. PMID:22802956

Ajemian, Matthew J; Powers, Sean P; Murdoch, Thaddeus J T

2012-07-03

322

A large population of king crabs in Palmer Deep on the west Antarctic Peninsula shelf and potential invasive impacts  

PubMed Central

Lithodid crabs (and other skeleton-crushing predators) may have been excluded from cold Antarctic continental shelf waters for more than 14 Myr. The west Antarctic Peninsula shelf is warming rapidly and has been hypothesized to be soon invaded by lithodids. A remotely operated vehicle survey in Palmer Deep, a basin 120 km onto the Antarctic shelf, revealed a large, reproductive population of lithodids, providing the first evidence that king crabs have crossed the Antarctic shelf. DNA sequencing and morphology indicate the lithodid is Neolithodes yaldwyni Ahyong & Dawson, previously reported only from Ross Sea waters. We estimate a N. yaldwyni population density of 10 600 km?2 and a population size of 1.55 × 106 in Palmer Deep, a density similar to lithodid populations of commercial interest around Alaska and South Georgia. The lithodid occurred at depths of more than 850 m and temperatures of more than 1.4°C in Palmer Deep, and was not found in extensive surveys of the colder shelf at depths of 430–725 m. Where N. yaldwyni occurred, crab traces were abundant, megafaunal diversity reduced and echinoderms absent, suggesting that the crabs have major ecological impacts. Antarctic Peninsula shelf waters are warming at approximately 0.01°C yr?1; if N. yaldwyni is currently limited by cold temperatures, it could spread up onto the shelf (400–600 m depths) within 1–2 decades. The Palmer Deep N. yaldwyni population provides an important model for the potential invasive impacts of crushing predators on vulnerable Antarctic shelf ecosystems.

Smith, Craig R.; Grange, Laura J.; Honig, David L.; Naudts, Lieven; Huber, Bruce; Guidi, Lionel; Domack, Eugene

2012-01-01

323

A large population of king crabs in Palmer Deep on the west Antarctic Peninsula shelf and potential invasive impacts.  

PubMed

Lithodid crabs (and other skeleton-crushing predators) may have been excluded from cold Antarctic continental shelf waters for more than 14 Myr. The west Antarctic Peninsula shelf is warming rapidly and has been hypothesized to be soon invaded by lithodids. A remotely operated vehicle survey in Palmer Deep, a basin 120 km onto the Antarctic shelf, revealed a large, reproductive population of lithodids, providing the first evidence that king crabs have crossed the Antarctic shelf. DNA sequencing and morphology indicate the lithodid is Neolithodes yaldwyni Ahyong & Dawson, previously reported only from Ross Sea waters. We estimate a N. yaldwyni population density of 10 600 km(-2) and a population size of 1.55 × 10(6) in Palmer Deep, a density similar to lithodid populations of commercial interest around Alaska and South Georgia. The lithodid occurred at depths of more than 850 m and temperatures of more than 1.4°C in Palmer Deep, and was not found in extensive surveys of the colder shelf at depths of 430-725 m. Where N. yaldwyni occurred, crab traces were abundant, megafaunal diversity reduced and echinoderms absent, suggesting that the crabs have major ecological impacts. Antarctic Peninsula shelf waters are warming at approximately 0.01°C yr(-1); if N. yaldwyni is currently limited by cold temperatures, it could spread up onto the shelf (400-600 m depths) within 1-2 decades. The Palmer Deep N. yaldwyni population provides an important model for the potential invasive impacts of crushing predators on vulnerable Antarctic shelf ecosystems. PMID:21900324

Smith, Craig R; Grange, Laura J; Honig, David L; Naudts, Lieven; Huber, Bruce; Guidi, Lionel; Domack, Eugene

2011-09-07

324

Realistic models of amorphous silica:?A comparative study of different potentials  

NASA Astrophysics Data System (ADS)

The creation of realistic models of amorphous silica has been studied using the Monte Carlo based method of Wooten, Winer, and Weaire, where the bond-topology is optimized with respect to an interatomic potential model. The commonly used Keating potentials are compared and their strengths and weaknesses are assessed. The mean oxygen bond-angle obtained using these potentials turned out to be too small. A modification of the potential parameters is shown to correct this feature and thus produce better results when used with the Wooten-Winer-Weaire method.

von Alfthan, S.; Kuronen, A.; Kaski, K.

2003-08-01

325

Potential Risks of Heavy Metal Pollution in Greenhouse Soils Cultivated for Different Periods  

Microsoft Academic Search

Assessing the concentration of potentially harmful heavy metals in the soil of greenhouses is important in order to evaluate the potential risks to humans. These risks may be higher in soils to which fertilizers have been applied over many years. To investigate this risk, the concentrations of copper (Cu), chromium (Cr), cadmium (Cd), lead (Pb) and zinc (Zn) were measured

Xia Huang; Tingxuan Li; Haiying Yu; Zicheng Zheng; Xizhou Zhang; Ping Huang

2011-01-01

326

Integral representation of voltage in half-plane conductor with embedded crack by D.C. potential difference method  

NASA Astrophysics Data System (ADS)

Non destructive testing (NDT) has been used to ensure safety in public structure and public space. D.C. potential difference method, one of the NDT, is used to detect a crack in a conductive material. In this paper we obtain an exact solution for model equation for D.C. potential difference method, which is the Laplace equation with an embedded crack in two dimensional half-space by using singular integral equation and angular potential. The solution can be computed and is useful for actual investigation of a crack.

Akira, Sasamoto; Krutitskii, P. A.

2013-10-01

327

The characteristics of the nematode faunas in subtidal sediments of a large microtidal estuary and nearshore coastal waters differ markedly  

NASA Astrophysics Data System (ADS)

The present study examines traditional paradigms regarding the differences between faunas in estuaries vs coastal waters. The ecological characteristics of the free-living nematode faunas of nearshore, subtidal sediments in downstream and upstream areas of the large, microtidal Swan River Estuary are compared with those similarly recorded seasonally in subtidal sediments along an adjacent part of the coast of temperate south-western Australia. Overall, the nematode species richness recorded in the upstream (38) and downstream estuarine areas (58) and from throughout the estuary (61) were substantially less than in marine waters (75). In addition, the value for Simpson's diversity index was marginally less in the estuary and the dominance of the most abundant species greater. In contrast, the mean nematode species richness and diversity in individual cores followed the reverse trend, reflecting a combination of less variability among the species compositions and far greater densities in the cores from estuarine sediments. Furthermore, the mean density (numbers 10 cm -2) was far higher in both upstream (341) and downstream (903) areas of the estuary than in marine waters (87). Although the compositions of the assemblages in upstream and downstream estuarine areas differed markedly from each other at the species, genus and family levels, these differences were less pronounced than those between either of these areas and marine waters. The trophic compositions at the moderately sheltered and fully exposed marine sites differed from that in both areas of the estuary, whereas that at the most sheltered marine site was similar to that in the downstream estuarine area, with both containing substantial proportions of epistrate-grazing species. The variations among the species richness, diversity, densities and taxonomic and trophic compositions of nematode assemblages in the sediments of the two estuarine areas and nearby marine waters appear to reflect differences in 1) salinity regimes, 2) extents of exposure to wave action and its related effects and 3) amounts and types of food available to nematodes.

Hourston, M.; Potter, I. C.; Warwick, R. M.; Valesini, F. J.

2011-07-01

328

Similarities and differences between a large meandering river and an anabranching river: the Ucayali and Amazon River cases  

NASA Astrophysics Data System (ADS)

The Ucayali is one of the largest freely meandering rivers in the world and its planform migration produces complex meander shapes dominated by not only fluvial erosion but mainly geotechnical processes since changes on water stage are appreciable compared to medium- and small-meander rivers. The Amazon is one of the largest anabranching rivers in the world and it is formed by the confluence of the anabranching Marañon River together with the meandering Ucayali River. The seasonal increase and decrease in water and sediment discharges from the Amazonian lowland rivers produce changes in the river’s planform configuration, river flooding, and streambank erosion affecting nearby towns and navigation and shoaling issues. Even though, extensive work has been dedicated to understand both river systems, there is still no absolute understanding of their physically-based formation processes and dynamics, especially at large scales as these lowland Amazonian rivers. The Ucayali Meandering River migrates at greater rates than the Amazon Anabranching River mainly due to their single channel condition; however localized secondary channels of the latter could behave as meandering channels dominating and modifying the planform dynamics of the entire anabranching system. Insights on how a large meandering river (Ucayali) is similar and at the same time different from an anabranching river (Amazon) will be described herein. A team composed of the Earth Processes & Environmental Flows Group (EPEF) at the University of Pittsburgh and the Directorate of Hydrology and Navigation (DHN) from the Peruvian Navy is working towards gathering information and field measurements concerning the dynamics of the Amazonian rivers. Therefore, based on three-dimensional velocity and bed morphodynamic measurements (performed in both river systems using acoustic profilers and echo sounders respectively) combined with mathematical hydrodynamic models, some insights on the flow structure, bed morphology and planform dynamics of large meandering and anabranching systems are presented.

Abad, J. D.; Paredes, J. R.; Montoro, H.

2010-12-01

329

Fog Forecasting using Synergy between Models of different Complexity: Large-Eddy Simulation, Column modelling and Limited Area Modelling  

NASA Astrophysics Data System (ADS)

Fog is a hazardous weather phenomenon with a large impact on the environment and human life. In particular the transportation sector is vulnerable to fog; but fog is also important for agriculture, for leaf-wetness duration in particular, and for humans with asthma or related diseases. In addition, fog and low level clouds govern to a large extent the radiation balance of the polar regions in summer, and as such fog also influences the regional climate. Hence a thorough understanding of the fog governing processes is essential. However, due to the complexity and small scale nature of the relevant physical processes, the current understanding is relatively poor, as is our ability to forecast fog. In order to improve our knowledge, and to identify key deficiencies in the current state of the art fog forecasting models, we present an experiment in which the synergy between models of different complexity and observations is used to evaluate model skill. Therefore, an observed case study (Cabauw; The Netherlands) of a well developed radiation fog will be innovatively run with a large eddy simulation model which allows us to evaluate the key issue of turbulent mixing. In addition, operational and research column models (PAFOG; Duynkerke, 1991) will be employed to evaluate their skill on the local scale, while at the limited area models WRF-NMMFOG (Mueller et al 2010) and COSMO-FOG will be evaluated on their skill for the regional scale. Special focus will be given to the representation of the boundary-layer vertical structure and turbulence in the latter two model types versus the LES results with its solid physical ground.

Steeneveld, G. J.; Masbou, M.; van Heerwaarden, C. C.; Mohr, C.; Schneider, W.; Müller, M.; Bott, A.; Holtslag, A. A. M.

2010-07-01

330

Testing different ecological scenarios in a temperate estuary: a contribution towards the implementation of the Ecological Potential assessment.  

PubMed

The concept of Ecological Potential was explored using the macrobenthic communities of the Mondego estuary (Portugal). Different scenarios (loss of a primary producer and intertidal habitat, and habitat modification due to hydromorphological changes and continued press perturbation) were tested to predict changes in the biology if hydromorphological pressures could be reversed, assuming that differences with and without the pressure could indicate the potential. Results showed noticeable changes in the system biology in each scenario. The approach followed, indicates that when data sets exist, differences in the measurement of ecological status with and without the hydromorphological change could be a way forward to determine the potential. In the particular case of the Mondego estuary, the South arm (physically unaltered water body) proved to be richer than the North (HMWB). For the Ecological Potential determination, the South arm could thus be used to derive and adjust future reference conditions for the North. PMID:23628548

Veríssimo, Helena; Patrício, Joana; Teixeira, Heliana; Carriço, Ana; Marques, João Carlos

2013-04-28

331

Production of very high potential differences by intracloud lightning discharges in connection with terrestrial gamma ray flashes  

NASA Astrophysics Data System (ADS)

Terrestrial gamma-ray flashes (TGFs) have been correlated with an early development stage of high altitude positive intracloud (+IC) flashes in which the negative leader propagates up toward the upper positive charge region, while the positive leader propagates down toward the lower negative charge region. The resultant bidirectional leaders develop electrical potential differences in the vicinity of their heads with respect to the ambient potential distribution created by the thundercloud charges. These potential differences are believed to be of essential importance for the generation of TGFs. Using electrostatic calculations and a three-dimensional Cartesian fractal model, we quantify these potential differences produced in a developing +IC lightning discharge for given thunderstorm electric configurations. We present a case of a +IC lightning discharge in a realistic thunderstorm configuration that leads to a very high (˜300 MV) potential difference and show how a delay in the development of the negative leader with respect to the positive one in a bidirectional leader system can facilitate a high potential difference in the negative leader head region.

Mallios, Sotirios A.; Celestin, Sebastien; Pasko, Victor P.

2013-02-01

332

Altitude Distribution of the Auroral Acceleration Potential Determined from Cluster Satellite Data at Different Heights  

SciTech Connect

Aurora, commonly seen in the polar sky, is a ubiquitous phenomenon occurring on Earth and other solar system planets. The colorful emissions are caused by electron beams hitting the upper atmosphere, after being accelerated by quasistatic electric fields at 1-2 R{sub E} altitudes, or by wave electric fields. Although aurora was studied by many past satellite missions, Cluster is the first to explore the auroral acceleration region with multiprobes. Here, Cluster data are used to determine the acceleration potential above the aurora and to address its stability in space and time. The derived potential comprises two upper, broad U-shaped potentials and a narrower S-shaped potential below, and is stable on a 5 min time scale. The scale size of the electric field relative to that of the current is shown to depend strongly on altitude within the acceleration region. To reveal these features was possible only by combining data from the two satellites.

Marklund, Goeran T.; Sadeghi, Soheil; Karlsson, Tomas; Lindqvist, Per-Arne [Space and Plasma Physics, School of Electrical Engineering, KTH, SE 10044 Stockholm (Sweden); Nilsson, Hans [Swedish Institute of Space Physics, Box 812, SE 981 28 Kiruna (Sweden); Forsyth, Colin; Fazakerley, Andrew [Mullard Space Science Laboratory, University College, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom); Lucek, Elizabeth A. [Space and Atmospheric Physics Group, Blacket Laboratory, Imperial College, London (United Kingdom); Pickett, Jolene [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242-1479 (United States)

2011-02-04

333

Species differences in the induction of time-dependent potentiation of insulin secretion.  

PubMed

The secretory responsiveness of the pancreatic beta-cell can be markedly improved by prior short term exposure to a stimulatory glucose level. Termed time-dependent potentiation (TDP), priming, or sensitization, this phenomenon has been documented to occur in both human and rat islets and my involve, at least in part, information flow in the phospholipase C and protein kinase C (PKC) signal transduction pathway. In contrast to human and rat islets, however, mouse islets fail to exhibit TDP in response to priming with high glucose. In the present series of studies, we explored in more detail the conditions and stimulants necessary for the induction of TDP in mouse islets and compared these responses with those obtained in rat islets. In agreement with previous reports, high (15 mM) glucose alone primed the rat beta-cell, but not the mouse beta-cell, to subsequent restimulation with 15 mM glucose. However, muscarinic stimulation of mouse islets with carbachol (100 microM) in the presence of 15 mM glucose primed the beta-cell to a subsequent 15-mM glucose stimulus. In addition, prior exposure to 50 nM of the PKC activator tetradecanoyl phorbol acetate dramatically amplified the subsequent insulin secretory responses of mouse islets to 15 mM glucose. In contrast to its significant inhibitory effect on glucose-induced insulin release from rat islets, the PKC inhibitor staurosporine (50 nM) had not effect on 15 mM glucose-induced release from control or prior glucose-exposed mouse islets. However, staurosporine significantly reduced the priming effect of tetradecanoyl phorbol acetate or carbachol on 15 mM glucose-induced insulin secretion from mouse islets. These findings emphasize the dramatic species differences that exist in the capacity of prior high glucose stimulation to induce TDP in rat and, presumably, human islets, on the one hand, and mouse islets, on the other. They also serve to emphasize the role of phosphoinositide hydrolysis and PKC activation in the induction of TDP. PMID:8612499

Zawalich, W S; Zawalich, K C

1996-05-01

334

Differential Osmosensing Signalling Pathways and G-protein Involvement in Human Cervical Cells with Different Tumour Potential  

Microsoft Academic Search

Previous studies show that the regulatory volume decrease (RVD) in human cervical cells with different tumour potential may be mediated by different ion channels. The signalling events involved in regulating these channel activities are not clear. To screen the possible mechanisms involved in cell volume regulation in these cells, we examine intracellular mechanisms and second messengers listed as follows: phospholipase

Meng-Ru Shen; Cheng-Yang Chou; Min-Lee Wu; Ko-En Huang

1998-01-01

335

Potential impact of benzodiazepine use on the rate of hip fractures in five large European countries and the United States.  

PubMed

Benzodiazepine use increases the risk of falls and has been associated with an increased risk of hip fractures. Our aim was to estimate the possible population impact of the use of benzodiazepines on the rate of hip fracture in France, Germany, Italy, Spain, the United Kingdom, and the United States. We conducted a literature review to estimate the pooled relative risk (RR) for hip fractures and use of benzodiazepines. Prevalence rates of benzodiazepine use in 2009 were calculated for each country using the IMS MIDAS database and three public databases in Denmark, the Netherlands, and Norway. Both the RR and prevalence rates were used for calculation of population attributable risks (PARs) of hip fractures associated with benzodiazepine use. The literature review showed an increased risk of hip fractures in benzodiazepine users (RR = 1.4, 95 % CI 1.2-1.6). Rate of benzodiazepine use showed considerable differences between countries, ranging from 4.7 % to 22.3 % of population ever in a 1-year period. These are reflected in results for the PARs; estimated attributions of benzodiazepines to the rate of hip fractures were 1.8 %, 95 % CI 1.1-2.6 (Germany); 2.0 %, 95 % CI 1.2-2.8 (United Kingdom); 5.2 %, 95 % CI 3.2-7.3 (Italy); 7.4 %, 95 % CI 4.5-10.0 (France); 8.0 %, 95 % CI 4.9-11.0 (United States); and 8.2 %, 95 % CI 5.1-12.0 (Spain). PAR estimates suggest that the potential attribution of benzodiazepine use on the population rate of hip fractures in the five specified European countries and the United States varies between 1.8 % and 8.2 %. During the next phase of the IMI-PROTECT study, a comparison with individual patient data will show whether this approach is valid. PMID:22566242

Khong, T P; de Vries, F; Goldenberg, J S B; Klungel, O H; Robinson, N J; Ibáñez, Luisa; Petri, H

2012-05-08

336

Analysis of adverse events of potential autoimmune aetiology in a large integrated safety database of AS04 adjuvanted vaccines.  

PubMed

Newly licensed vaccines against human papillomavirus (HPV) and hepatitis B (HBV), and several vaccines in development, including a vaccine against genital herpes simplex virus (HSV), contain a novel Adjuvant System, AS04, composed of 3-O-desacyl-4' monophosphoryl lipid A and aluminium salts. Given the background incidence of autoimmune disorders in some of the groups targeted for immunisation with these vaccines, it is likely that autoimmune events will be reported in temporal association with vaccination, even in the absence of a causal relationship. The objective of this integrated analysis was to assess safety of AS04 adjuvanted vaccines with regard to adverse events (AEs) of potential autoimmune aetiology, particularly in adolescents and young adults. All randomised, controlled trials of HPV-16/18, HSV and HBV vaccines were analysed in an integrated analysis of individual data (N = 68,512). A separate analysis of the HPV-16/18 vaccine trials alone was also undertaken (N = 39,160). All data were collected prospectively during the vaccine development programmes (mean follow-up of 21.4 months), and included in the analysis up to a pre-defined data lock point. Reporting rates of overall autoimmune events were around 0.5% and did not differ between the AS04 and control groups. The relative risk (AS04/control) of experiencing any autoimmune event was 0.98 (95% confidence intervals 0.80, 1.21) in the integrated analysis and 0.92 (0.70, 1.22) in the HPV-16/18 vaccine analysis. Relative risks calculated overall, for disease category or for individual events were close to 1, and all confidence intervals around the relative risk included 1, indicating no statistically significant difference in event rates between the AS04 and control groups. This integrated analysis of over 68,000 participants who received AS04 adjuvanted vaccines or controls demonstrated a low rate of autoimmune disorders, without evidence of an increase in relative risk associated with AS04 adjuvanted vaccines. PMID:18845199

Verstraeten, Thomas; Descamps, Dominique; David, Marie-Pierre; Zahaf, Toufik; Hardt, Karin; Izurieta, Patricia; Dubin, Gary; Breuer, Thomas

2008-12-01

337

Investigation of candidate genes for glycolytic potential of porcine skeletal muscle: Association with meat quality and production traits in Italian Large White pigs  

Microsoft Academic Search

The objective of this study was to investigate the association of DNA markers in candidate genes for glycolytic potential on meat quality parameters (pH1, pHu, glycogen and lactate content and glycolytic potential of semimembranosus muscle) and estimated breeding values (EBVs) for average daily gain, lean cuts, back fat thickness, ham weight, and feed:gain ratio in 272 Italian Large White pigs.

L. Fontanesi; R. Davoli; L. Nanni Costa; F. Beretti; E. Scotti; M. Tazzoli; F. Tassone; M. Colombo; L. Buttazzoni; V. Russo

2008-01-01

338

Is splash erosion potential species specific? Measuring of splash erosion potential under forest in different succession stages along a biodiversity gradient in the humid subtropics  

NASA Astrophysics Data System (ADS)

It is widely accepted that (forest) vegetation is a key control for the type and intensity of soil erosion. The current paradigm is that natural or quasi-natural vegetation protects the soil from erosion and that agricultural vegetation or land use generally enhances erosion. The latter was in focus of most research during the last decades and less interest was paid on natural systems, which are more difficult to study. Nevertheless, afforestation is widely used as a measure of soil protection against soil erosion. Rainfall can be highly erosive particularly in the humid subtropics. Regarding climate change, also precipitation regime may change in direction to even more severe storms and higher rainfall intensities; it is a research field of growing importance. Key mechanisms of a vegetation cover in reducing or enhancing erosion are modifications of drop-size distribution, retention of raindrop impact on the soil and changes in amount and spatial distribution of rainfall at the ground surface. Controlling determinants are rainfall intensity, drop size distribution, drop fall velocity, height of the canopy as well as density of the canopy, crown and leaf traits, LAI and coverage by a litter layer. Large drops are supposed to be significant sources of splash detachment in forests (Brandt 1989; Vis 1986). However, the mechanisms of reducing (or enhancing?) splash detachment under forest in relation to species richness and species composition are not well understood. Some studies indicate that raindrop impact is species specific (Calder 2001; Nanko et al. 2006) and some neglect the effects of species specific impacts (Foot & Morgan 2005). Our research uses different methods of rainfall characterization (splash cups, tipping-bucket rain gauge, laser distrometer) to reveal the described mechanisms from the canopy through different vegetation layers to the ground. First results of splash cup measurements (revised after Ellison 1947) show that sand loss under vegetation is 2.5 times higher than in open field despite the fact that only 60 percent of open field rainfall reaches the ground. The results also indicate that sand loss is a function of the age of the specific forest stand and the variability of sand loss under different species with respect to space and time. These and future results will help managing afforestation projects in giving implications which of the species (resp. species compositions) may reduce most effectively potential splash erosion. References: Brandt, C. J. (1989): The size distribution of throughfall drops under vegetation canopies. Catena 16, p. 507-524. Calder, I. R. (2001): Canopy processes: implications for transpiration, interception and splash induced erosion, ultimately for forest management and water resources. Plant Ecology 153, p. 203-214. Ellison, W. D. (1947): Soil Erosion Studies - Part II. Soil Detachment Hazard by Raindrop Splash. Agricultural Engineering 28, p. 197-201. Foot, K.; Morgan, R. P. C. (2005): The role of leaf inclination, leaf orientation and plant canopy architecture in soil particle detachment by raindrops. Earth Surface Processes and Landforms 30, p. 1509-1520. Nanko, K.; Hotta, N. & Suzuki, M. (2006): Evaluating the influence of canopy species and meteorological factors on throughfall drop size distribution. Journal of Hydrology 329, p. 422-431. Vis, M. (1986): Interception, drop size distributions and rainfall kinetic energy in four colombian forest ecosystems. Earth Surface Processes and Landforms 11, p. 591-603.

Geißler, C.; Kühn, P.; Scholten, T.

2009-04-01

339

Structural Rationalization of a Large Difference in RNA Affinity Despite a Small Difference in Chemistry between Two 2'-O-Modified Nucleic Acid Analogs  

SciTech Connect

Chemical modification of nucleic acids at the 2'-position of ribose has generated antisense oligonucleotides (AONs) with a range of desirable properties. Electron-withdrawing substituents such as 2'-O-[2-(methoxy)ethyl] (MOE) confer enhanced RNA affinity relative to that of DNA by conformationally preorganizing an AON for pairing with the RNA target and by improving backbone hydration. 2'-Substitution of the ribose has also been shown to increase nuclease resistance and cellular uptake via changes in lipophilicity. Interestingly, incorporation of either 2'-O-[2-(methylamino)-2-oxoethyl]- (NMA) or 2'-O-(N-methylcarbamate)-modified (NMC) residues into AONs has divergent effects on RNA affinity. Incorporation of 2'-O-NMA-T considerably improves RNA affinity while incorporation of 2'-O-NMC-T drastically reduces RNA affinity. Crystal structures at high resolution of A-form DNA duplexes containing either 2'-O-NMA-T or 2'-O-NMC-T shed light on the structural origins of the surprisingly large difference in stability given the relatively minor difference in chemistry between NMA and NMC. NMA substituents adopt an extended conformation and use either their carbonyl oxygen or amino nitrogen to trap water molecules between phosphate group and sugar. The conformational properties of NMA and the observed hydration patterns are reminiscent of those found in the structures of 2'-O-MOE-modified RNA. Conversely, the carbonyl oxygen of NMC and O2 of T are in close contact, providing evidence that an unfavorable electrostatic interaction and the absence of a stable water structure are the main reasons for the loss in thermodynamic stability as a result of incorporation of 2'-O-NMC-modified residues.

Pattanayek, R.; Sethaphong, L.; Pan, C.; Prhavc, M.; Prakash, T.P.; Manoharan, M.; Egli, M. (Tennessee); (Isis Pharmaceuticals Inc.); (Alnylam Pharmaceuticals,); (Vanderbilt)

2010-03-08

340

Differences in the cytogenetic alteration profiles of diffuse large B-cell lymphoma among Chinese and American patients.  

PubMed

To study the similarities and differences of cytogenetic alterations in diffuse large B-cell lymphoma (DLBCL) between Asian and Caucasian patients, we compared the cytogenetic profiles of Chinese and American DLBCL cases by analyzing conventional karyotypes and select fluorescence in situ hybridization (FISH) findings. We used interphase FISH analyses to determine the incidence of the t(14;18) and BCL6 and MYC rearrangements. Immunohistochemical analysis was used to categorize the lymphomas into the germinal center B-cell-like (GCB) or non-GCB-DLBCL subtypes, according to the Hans algorithm. Our data suggested that Chinese patients had cytogenetic profiles for GCB-DLBCL that differed from those of their American counterparts; specifically, the Chinese GCB patients exhibited greater frequencies of BCL6 rearrangements and gains of 1q and 11q but lower incidence of the t(14;18). Non-GCB-DLBCL in both the Chinese and American patients was characterized by recurrent gains of 3/3q and 18/18q. The incidences of both BCL6 rearrangement and t(14;18) were similar in Chinese and American non-GCB-DLBCL cases. PMID:23849050

Chen, Yan; Dave, Bhavana J; Zhu, Xiongzeng; Chan, Wing C; Iqbal, Javeed; Sanger, Warren G; Fu, Kai

2013-05-01

341

Molecular View of Cholesterol Flip-Flop and Chemical Potential in Different Membrane Environments  

Microsoft Academic Search

The relative stability of cholesterol in cellular membranes and the thermodynamics of fluctuations from equilibrium have important consequences for sterol trafficking and lateral domain formation. We used molecular dynamics computer simulations to investigate the partitioning of cholesterol in a systematic set of lipid bilayers. In addition to atomistic simulations, we undertook a large set of coarse grained simulations, which allowed

W. F. Drew Bennett; Justin L. MacCallum; Marlon J. Hinner; Siewert J. Marrink; D. Peter Tieleman

2009-01-01

342

Study of fusion probabilities with halo nuclei using different proximity based potentials  

NASA Astrophysics Data System (ADS)

We study fusion of halo nuclei with heavy targets using proximity based potentials due to Aage Winther (AW) 95, Bass 80 and Proximity 2010. In order to consider the extended matter distribution of halo nuclei, the nuclei radii borrowed from cross section measurements are included in these potentials. Our study reveals that the barrier heights are effectively reduced and fusion cross sections are appreciably enhanced by including extended radii of these nuclei. We also find that the extended sizes of halos contribute towards enhancement of fusion probabilities in case of proton halo nuclei, but, contribute to transfer or break-up process rather than fusion yield in case of neutron halo nuclei.

Kumari, Raj

2013-11-01

343

The large-scale evolution by generating new genes from gene duplication; similarity and difference between monoploid and diploid organisms.  

PubMed

On the basis of the concept of biological activity, the large-scale evolution by generating new genes from gene duplication is theoretically compared between the monoploid organism and the diploid organism. The comparison is carried out not only for the process of generating one new gene but also for the process of generating two or more kinds of new genes from successive gene duplication. This comparison reveals the following difference in evolutionary pattern between the monoploids and diploids. The monoploid organism is more suitable to generate one or two new genes step by step but its successive gene duplication is obliged to generate smaller sizes of genes by the severer lowering of biological activity or self-reproducing rate. This is consistent with the evolutionary pattern of prokaryotes having steadily developed chemical syntheses, O?-releasing photosynthesis and O?-respiration in the respective lineages. On the other hand, the diploid organism with the plural number of homologous chromosome pairs has a chance to get together many kinds of new genes by the hybridization of variants having experienced different origins of gene duplication. Although this strategy of hybridization avoids the severe lowering of biological activity, it takes the longer time to establish the homozygotes of the more kinds of new genes. During this long period, furthermore different types of variants are accumulated in the population, and their successive hybridization sometimes yields various styles of new organisms. This evolutionary pattern explains the explosive divergence of body plans that has occasionally occurred in the diploid organisms, because the cell differentiation is a representative character exhibited by many kinds of genes and its evolution to the higher hierarchy constructs body plans. PMID:21402082

Otsuka, Jinya

2011-03-12

344

From a different perspective: principles, practice and potential of bistatic radar  

Microsoft Academic Search

Bistatic radar systems have been studied and built since the earliest days of radar. They have the advantages that the receivers are passive, and hence undetectable. The receiving systems are also potentially simple and cheap. Bistatic radar may have a counter-stealth capability, since target shaping to reduce monostatic RCS will in general not reduce the bistatic RCS. In spite of

H. D. Griffiths

2003-01-01

345

Predicting Reading Growth with Event-Related Potentials: Thinking Differently about Indexing "Responsiveness"  

ERIC Educational Resources Information Center

The purpose of this study was to determine if event-related potential (ERP) data collected during three reading-related tasks (Letter Sound Matching, Nonword Rhyming, and Nonword Reading) could be used to predict short-term reading growth on a curriculum-based measure of word identification fluency over 19 weeks in a sample of 29 first-grade…

Lemons, Christopher J.; Key, Alexandra P. F.; Fuchs, Douglas; Yoder, Paul J.; Fuchs, Lynn S.; Compton, Donald L.; Williams, Susan M.; Bouton, Bobette

2010-01-01

346

Potential fire behavior in pine flatwood forests following three different fuel reduction techniques  

Microsoft Academic Search

A computer modeling study to determine the potential fire behavior in pine flatwood forests following three fuel hazard reduction treatments: herbicide, prescribed fire and thinning was conducted in Florida following the 1998 wildfire season. Prescribed fire provided immediate protection but this protection quickly disappeared as the rough recovered. Thinning had a similar effect on fireline intensity. Herbicides produced a dramatic

Patrick Brose; Dale Wade

2002-01-01

347

Microstates in language-related brain potential maps show noun-verb differences  

Microsoft Academic Search

Brain processing of grammatical word class was studied analyzing event-related potential (ERP) brain fields. Normal subjects observed a randomized sequence of single German nouns and verbs on a computer screen, while 20-channel ERP field map series were recorded separately for both word classes. Spatial microstate analysis was applied, based on the observation that series of ERP maps consist of epochs

Thomas H. Koenig; Dietrich Lehmann

1996-01-01

348

Predicting Reading Growth with Event-Related Potentials: Thinking Differently about Indexing "Responsiveness"  

ERIC Educational Resources Information Center

|The purpose of this study was to determine if event-related potential (ERP) data collected during three reading-related tasks (Letter Sound Matching, Nonword Rhyming, and Nonword Reading) could be used to predict short-term reading growth on a curriculum-based measure of word identification fluency over 19 weeks in a sample of 29 first-grade…

Lemons, Christopher J.; Key, Alexandra P. F.; Fuchs, Douglas; Yoder, Paul J.; Fuchs, Lynn S.; Compton, Donald L.; Williams, Susan M.; Bouton, Bobette

2010-01-01

349

Beta-actin in human colon adenocarcinoma cell lines with different metastatic potential  

Microsoft Academic Search

Human colon adenocarcinoma LS180 parental cell line and selected variants, characterized by dif- ferent metastatic capacity were used to examine, whether a correlation exists between ?-actin ex- pression, its subcellular distribution and metastatic potential of these cells. Cytosolic fraction (su- pernatant 105 000 × g), isolated from the tumor cells was used as a source for actin quantification. The higher

Dorota Nowak; Aneta Skwarek-Maruszewska; Magdalena Zemanek-Zboch; Maria Malicka-B?aszkiewicz

2005-01-01

350

Potential job applicant reactions to employee drug testing: The effect of program characteristics and individual differences  

Microsoft Academic Search

An experiment varied two aspects of employee drug-testing programs: the purpose of the program (to rehabilitate or to punish) and the drug-testing selection method (for due cause or random and mandatory). Dependent variables were potential job applicants' attitudes toward, intention to apply to, and willingness to accept a job offer from the company. Although the manipulations had no effects, several

J. Michael Crant; Thomas S. Bateman

1993-01-01

351

Event-related potentials index cognitive style differences during a serial-order recall task  

Microsoft Academic Search

Working memory and attentional inhibition processes (jointly symbolized here as WM\\/I) have been proposed to explain cognitive style differences in Field Dependence–Independence (FDI). FI relative to FD subjects have been found to use more effectively WM\\/I to operate on task-relevant information. The purpose of this study was to determine whether cognitive style differences are revealed as differences in ERP activity

Patrick E. Goode; Phil H. Goddard; Juan Pascual-Leone

2002-01-01

352

Study of the Spin/Orbit Term of the Spherical Optical Model Potential by Means of Large Angle Fast Neutron Elastic Scattering Angular Distribution Measurements.  

National Technical Information Service (NTIS)

The study of differential cross section angular distributions for neutron elastic scattering at large angles is a sensitive method for testing the effect of the choice of the numerical value of the spin-orbit term of the optical model potential. This is o...

E. Ramstroem B. Trostell

1978-01-01

353

Evaluation of the Potential Impact of Age and Gender-Specific Pharmacokinetic Differences on Tissue Dosimetry  

Microsoft Academic Search

The physiological and biochemical processes that determine the tissue concentration time courses (pharmacokinetics) of xenobiot- ics vary, in some cases significantly, with age and gender. While it is known that age- and gender-specific differences have the po- tential to affect tissue concentrations and, hence, individual risk, the relative importance of the contributing processes and the quantitative impact of these differences

Harvey J. Clewell; P. Robinan Gentry; Tammie R. Covington; Ramesh Sarangapani; Justin G. Teeguarden

2004-01-01

354

Growth, stomatal resistance, and transpiration of Aloe vera under different soil water potentials  

Microsoft Academic Search

Aloe vera (Sábila) is used in folklore medicine and commercial cosmetology products in many countries. Little is known about the plant's physiological, growth, and yield responses under different irrigation regimes. The plant has a crassulacean acid metabolism (CAM) that allows water conservation within the tissue, and therefore, resistance to high water stress. A. vera plants were submitted to different irrigation

R. Rodríguez-García; D. Jasso de Rodríguez; J. A. Gil-Marín; J. L. Angulo-Sánchez; R. H. Lira-Saldivar

2007-01-01

355

Gender Differences in Characteristics Desired in a Potential Sexual and Marriage Partner  

Microsoft Academic Search

Only recently have researchers recognized that the qualities that are considered desirable in a short-term sexual partner may differ from those sought in a long-term marriage partner. To investigate this hypothesis, and to explore gender differences in what are considered to be sexually as opposed to maritally desirable characteristics, 70 men and women ranked a set of 23 characteristics in

Pamela C. Regan; Ellen Berscheid

1997-01-01

356

A comparative study of sub-barrier fusion using different proximity based potentials  

NASA Astrophysics Data System (ADS)

We study fusion probabilities at sub-barrier energies using potentials due to AW 95, Bass 80, Denisov DP and Proximity 2010. The fusion reactions for 16O+70,72Ge, 27Al+70,72Ge, 40Ca+48,50Ti, 40Ca+58,62Ni, 32S+90,96Zr and 40Ca+90,96Zr are studied at sub-barrier energies. We find that our theoretical calculations using all these proximity based potentials nicely explain the sub-barrier fusion cross-sections for the reaction series of O+Ge. However, small deviations are observed in sub-barrier region in case of other reactions and are attributed to deformed shape of the nuclei, surface vibrations and multi-neutron transfer channels.

Kumari, Raj

2013-04-01

357

Spin density contribution to heavy ion potentials using different nucleonic densities  

SciTech Connect

Within the Skyrme energy density formalism, an analytical formula for the spin density part of the heavy ion interaction potential is obtained for 1s-0d shell nuclei by using the shell model density consistently. Comparisons are made with similar results for the parametrized Fermi density distribution which are useful for their later use in the calculations of fusion cross sections. {copyright} {ital 1997} {ital The American Physical Society}

Sharma, M.K.; Kumar, H.; Puri, R.K.; Gupta, R.K. [Centre of Advanced Study in Physics, Panjab University, Chandigarh 160014 (India)

1997-08-01

358

Bilateral differences in brain potentials from the two cerebral hemispheres in relation to laterality and stuttering  

Microsoft Academic Search

An analysis of brain potential records simultaneously obtained from the right and left occipital region showed that alpha waves in the two hemispheres are out of phase a greater percent of the time in ambidextrous and left-handed subjects than in right-handed subjects; also that there is less unilateral blocking in the right-handed group. Records from two stutterers showed a degree

D. B. Lindsley

1940-01-01

359

Event-related potentials findings differ between children and adults during arithmetic-fact retrieval  

Microsoft Academic Search

Some cognitive abilities of arithmetical calculation depend on retrieval of arithmetic facts from long-term memory. Arithmetic-fact retrieval has been studied in adults through Event-Related Potentials (ERP) experiments. Such information in children, however, has been scarce. It has been reported that from the age of 9 years, children employ a memory retrieval strategy for solving simple multiplication problems. The present study

Belén Prieto-Corona; Mario Rodríguez-Camacho; Juan Silva-Pereyra; Erzsébet Marosi; Thalía Fernández; Vicente Guerrero

2010-01-01

360

A Different Form of Long-Lasting Potentiation Revealed in Tissue Plasminogen Activator Mutant Mice  

Microsoft Academic Search

The establishment of hippocampal long-term potentiation (LTP) requires protein and mRNA synthesis, suggesting that neuronal activity resulting in LTP initiates a cascade of gene expression. The expression of the gene for the extracellular serine protease tissue plasminogen activator (t-PA) is induced during LTP. Here we analjlze long-lasting LTP (L-LTP, >4 hr) in CA1 hippocampal slices of mice homozygous for disrupted

Uwe Frey; Michael Miiller; Dietmar Kuhl

1996-01-01

361

Simultaneous projection and detection system of four different frequencies for microwave imaging reflectometry in Large Helical Device  

SciTech Connect

A simultaneous projection/detection system of four different frequencies for microwave imaging reflectometry (MIR) was developed for three-dimensional observation of electron density fluctuations in the Large Helical Device (LHD). The microwave with four frequency components at 60.410, 61.808, 63.008, and 64.610 GHz is projected in a continuous-wave mode to illuminate the target LHD plasma. A two-dimensional horn-antenna mixer array (2D HMA) receives the reflected wave from the plasma as well as the wave from the local oscillator operating at 55.800 GHz. The first intermediate frequency (IF) signals at 4.610, 6.008, 7.208, and 8.810 GHz were confirmed to be obtained by downconversion of these microwaves using the 2D HMA. Each of these first IF components is filtered from each other and downconverted again for the superheterodyne detection. It was confirmed that both the amplitudes and the phases of the detected signals reflect the fluctuations in LHD plasmas.

Yoshinaga, T.; Nagayama, Y.; Tsuchiya, H. [National Institute for Fusion Science, 322-6 Oroshi, Toki 509-5292 (Japan); Kuwahara, D.; Tsuji-Iio, S. [Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro 152-8550 (Japan); Yamaguchi, S. [Kansai University, 3-3-35 Yamate, Suita 564-8680 (Japan); Kogi, Y. [Fukuoka Institute of Technology, 3-30-1 Wajiro-Higashi, Fukuoka 811- 0295 (Japan); Mase, A. [Kyushu University, 6-1 Kasuga-Koen, Kasuga 816-8680 (Japan)

2010-10-15

362

Functional Magnetic Resonance Imaging Shows Potential for Predicting Individual Differences in Fatigue Vulnerability.  

National Technical Information Service (NTIS)

Fatigue from sleep loss exerts deleterious effects on group performance, and some individuals are more affected than others. Underlying pattern of cortical activation may partially account for such individual differences. The present research utilized fMR...

J. A. Caldwell J. K. Smith J. L. Caldwell Q. Mu M. George

2004-01-01

363

Large-Scale Gene Expression Profiling of Discrete Brain Regions: Potential, Limitations, and Application in Genetics of Aggressive Behavior  

Microsoft Academic Search

Many behavioral geneticists are interested in unraveling the molecular mechanisms underlying aggressive behavior. So far, most scientists have based their search for aggression-related genes on a preliminary functional hypothesis. Large-scale gene expression profiling techniques, such as serial analysis of gene expression (SAGE) and DNA microarrays, now enable the screening of expression levels of thousands of genes simultaneously, allowing the identification

Dorine E. M. Feldker; E. Ronald de Kloet; Menno R. Kruk; Nicole A. Datson

2003-01-01

364

Focused ion beam induced local modifications of the contact potential difference of n- and p-doped silicon  

Microsoft Academic Search

Kelvin probe microscopy (KPM) has been used to investigate n-doped and p-doped silicon processed with a Ga+ focused ion beam (FIB) for doses up to 2.5 × 1018 cm-2. KPM measurements reveal that FIB processing induces dose dependent, highly localized modifications of the contact potential difference (CPD) within the previously homogeneous silicon specimens. Significant characteristic differences in the CPD are

M. A. Stevens-Kalceff; D. P. Kruss

2009-01-01

365

Focused ion beam induced local modifications of the contact potential difference of n- and p-doped silicon  

Microsoft Academic Search

Kelvin probe microscopy (KPM) has been used to investigate n-doped and p-doped silicon processed with a Ga+ focused ion beam (FIB) for doses up to 2.5 × 1018 cm?2. KPM measurements reveal that FIB processing induces dose dependent, highly localized modifications of the contact potential difference (CPD) within the previously homogeneous silicon specimens. Significant characteristic differences in the CPD are

M A Stevens-Kalceff; D P Kruss

2009-01-01

366

Ionic basis of the different action potential configurations of single guinea-pig atrial and ventricular myocytes.  

PubMed Central

Single myocardial cells were enzymatically dispersed from guinea-pig atria and ventricles. At 25 degrees C, atrial cell action potentials differed significantly from ventricular cell action potentials in duration (atrial = 141 ms, ventricular = 497 ms) and over-shoot (atrial = +36 mV, ventricular = +42 mV). Action potentials of atrial and ventricular cells responded differently to changes in external K+ concentration ([K+]o). Elevation of [K+]o from 6 to 11 mM depolarized atrial cells but produced no significant change in action potential duration; similar changes in [K+]o depolarized ventricular cells and produced a significant shortening of the action potential duration. Voltage-clamp experiments were performed to investigate the ionic basis underlying the different action potential configurations of single atrial and ventricular myocytes. A single-micropipette voltage-clamp technique was used, employing either extremely small-tip diameter pipettes, without internal cell dialysis (Hume & Giles, 1983), or larger tip diameter pipettes, with internal dialysis (Hamill, Marty, Neher, Sakmann & Sigworth, 1981). Two significant differences in background K+ conductance in single atrial and ventricular myocytes were observed: (i) the isochronal (5 s) current-voltage relationship of single ventricular myocytes exhibited a region of prominent negative slope conductance and elevation of [K+]o produced cross-over; a negative slope conductance region was absent in atrial cells and elevation of [K+]o produced very little cross-over of isochronal current-voltage relationships, and (ii) hyperpolarizing voltage pulses applied from holding potentials of -50 mV elicited inward current in ventricular cells which decayed with time; similar voltage-clamp pulses in atrial cells elicited inward currents which fail to decay. Single K+ channel current measurements confirmed the existence of different resting K+ channel properties in single atrial and ventricular myocytes. Resting K+ channels in both cell types had similar single channel conductances (30-32 pS with [K+]o = 145 mM) but ventricular K+ channels had significantly slower gating kinetics compared to atrial K+ channels (ventricular K+ channel mean open time = 223 ms; atrial K+ channel mean open time = 1 ms at Vr (resting membrane potential) -20 mV). The plateau and duration of the guinea-pig ventricular action potential was insensitive to high concentrations of tetrodotoxin (3 X 10(-5) M) but extremely sensitive to external Ca2+ concentration ([Ca2+]o). The second inward Ca2+ current (iCa) density was estimated in small atrial and ventricular myocytes of similar diameter and length.(ABSTRACT TRUNCATED AT 400 WORDS) Images Plate 1

Hume, J R; Uehara, A

1985-01-01

367

The large-leaved Kudingcha (Ilex latifolia Thunb and Ilex kudingcha C.J. Tseng): a traditional Chinese tea with plentiful secondary metabolites and potential biological activities.  

PubMed

In China, Kudingcha has been used for almost 2,000 years as a tea to quench thirst, remove phlegm, refresh the mind, and improve eyesight. The group of large-leaved Kudingcha is coveted for its potential effects on lipid metabolism, which are attributed to the presence of characteristic ingredients. This contribution reviews studies from the past few decades regarding the plant characteristics, ethnobotanical usages, chemical constituents, and related biological activities of the large-leaved Kudingcha (Ilex latifolia Thunb and Ilex kudingcha C.J. Tseng). Triterpenoids, phenolic acids, flavonoids, and essential oils are the main metabolites in the large-leaved Kudingcha, and these ingredients protect the vascular system, regulate lipid metabolism, and have antioxidant, hypoglycemic, and anti-tumor effects. Moreover, large-leaved Kudingcha shares several properties with the popular green tea and the Yerba maté from South America. PMID:23529541

Li, Li; Xu, Li J; Ma, Gui Z; Dong, Yin M; Peng, Yong; Xiao, Pei G

2013-03-26

368

Recent progress on phospholipases: different sources, assay methods, industrial potential and pathogenicity.  

PubMed

Significant studies on phospholipases optimization, characterization, physiological role and industrial potential have been conducted worldwide. Some of them have been directed for biotechnological advances such as gene discovery and functional enhancement by protein engineering. Others reported phospholipases as virulence factor and major cause of pathophysiological effects. A general overview on phospholipase is needed for the identification of new reliable and efficient phospholipase, which would be potentially used in number of industrial and medical applications. Phospholipases catalyse the hydrolysis of one or more ester and phosphodiester bonds of glycerophospholipids. They vary in site of action on phospholipid which can be used industrially for modification/production of new phospholipids. Catalytically active phospholipase mainly use phosphatidylcholine as major substrate, but they can also show specificity with other phospholipids. Several accurate phospholipase assay methods are known, but a rapid and reliable method for high-throughput screening is still a challenge for efficient supply of superior phospholipases and their practical applications. Major application of phospholipase is in industries like oil refinery, health food manufacturing, dairy, cosmetics etc. All types of phospholipases can be involved as virulence factor. They can also be used as diagnostic markers for microbial infection. The importance of phospholipase in virulence is proven and inhibitors of the enzyme can be used as candidate for preventing the associated disease. PMID:21302142

Ramrakhiani, Lata; Chand, Subhash

2011-02-08

369

Identification of conserved potentially regulatory sequences of the SRY gene from 10 different species of mammals.  

PubMed

We have sequenced the 5' region of the SRY gene from human, chimpanzee, sheep, and mouse and from four additional mammalian species, not previously characterized (gorilla, gazelle, rat, and guinea pig). In order to identify conserved DNA elements potentially involved in the regulation of the SRY gene, the newly determined sequences were analyzed and compared to all mammalian SRY promoter sequences available at present. Ten highly conserved potential regulatory elements have been identified in all 10 species (AP1, Barbie, GATA, Gfi1, cMyb, vMyb, NF1, Oct1, Sp1, and SRY). The known function of several of these regulatory elements fits well with the known expression of the SRY gene. However, except for the highly conserved coding HMG motif, only a short region close to the initiation of transcription in the human SRY is conserved in the exact position along the gene in all the species analyzed. This lack of sequence identity at the orthologous positions is consistent with the suggested rapid evolution of the SRY gene. This relative lack of homology contrasts with a high sequence identity of the putative regulatory sequences found within each taxonomic group of species (primates, bovids, and rodents), which supports a common mechanism of SRY expression and possibly also a similar function. PMID:9571157

Margarit, E; Guillén, A; Rebordosa, C; Vidal-Taboada, J; Sánchez, M; Ballesta, F; Oliva, R

1998-04-17

370

Mechanisms of action of bisphosphonates: similarities and differences and their potential influence on clinical efficacy  

Microsoft Academic Search

Summary  Bisphosphonates (BPs) are well established as the leading drugs for the treatment of osteoporosis. There is new knowledge\\u000a about how they work. The differences that exist among individual BPs in terms of mineral binding and biochemical actions may\\u000a explain differences in their clinical behavior and effectiveness.\\u000a \\u000a \\u000a \\u000a Introduction  The classical pharmacological effects of bisphosphonates (BPs) appear to be the result of two

R. G. G. Russell; N. B. Watts; F. H. Ebetino; M. J. Rogers

2008-01-01

371

Regional differences in HIV prevalence among drug users in China: potential for future spread of HIV?  

PubMed Central

Background Drug use and in particular injecting drug use has been at the forefront of the explosive spread of HIV in general populations in many countries in Asia. There is concern that also in China increased HIV incidence in drug users might spark off a generalized epidemic in the wider population. Close monitoring of HIV incidence and risk factors in drug users is therefore important to be able to target interventions effectively. Second generation surveillance was launched to assess HIV prevalence and risk behaviours jointly with the purpose of describing trends and predicting future developments. To assess whether these goals were fulfilled among drug users in China we provide an analysis of risk factors for HIV infection and of regional differences in HIV prevalence. Methods We analysed data collected in 2005 in 21 drug user second generation surveillance sentinel sites from 14 provinces in China. We used random effects logistic regression to test for risk factors for HIV infection and regional differences. Results The overall HIV-1 antibody prevalence was 5.4% (279/5128); 4.9% among injecting drug users (IDU) not sharing needles and 3.7% among non-injecting drug users. We found substantial heterogeneity among the surveillance sites with prevalence rates ranging between 0% and 54%. HIV status was strongly affected by the regional prevalence of HIV. Risk behaviours were highly prevalent in regions where HIV prevalence is still low. The distribution of duration of drug use in different sites indicated different stages of the drug use epidemics. Conclusion ]Regional differences in HIV prevalence in China reflect different stages of the drug use and HIV epidemics rather than differences in risk behaviours. Therefore, outbreaks of HIV among drug users in regions where prevalence is still low can be expected in the future. However, methodological limitations of surveillance embedded into routine systems limit the usability of existing data. More standardized approaches to data collection in secondary generation HIV surveillance are necessary to better understand regional differences in risk behaviour and prevalence and to design targeted intervention for those regions at risk of experiencing outbreaks.

Kretzschmar, Mirjam; Zhang, Weidong; Mikolajczyk, Rafael T; Wang, Lan; Sun, Xinhua; Kraemer, Alexander; Lv, Fan

2008-01-01

372

Effect of Aquasorb and Organic Compost Amendments on Soil Water Retention and Evaporation with Different Evaporation Potentials and Soil Textures  

Microsoft Academic Search

Aquasorb PR3005A, a hydrophilic polymer (a salt copolymer polyacrylamide), and garden waste compost were added to a loamy sand and a loam soil in pots to assess their impact upon soil physical properties at two different evaporation potentials. Compost was mulched and incorporated, the Aquasorb was incorporated, and their effect on temperature and amelioration of soil water content and evaporation

M. Taban; S. A. R. Movahedi Naeini

2006-01-01

373

Cryopreservation of cultured periosteum: Effect of different cryoprotectants and pre-incubation protocols on cell viability and osteogenic potential  

Microsoft Academic Search

Evidence has accumulated that periosteal cells have a great potential to regenerate bone. We have demonstrated that cultured periosteum (CP) in membrane form is an effective device to regenerate alveolar bone. To increase the availability of CP in a clinical environment, an effective cryopreservation protocol for CP has been developed. In this study, three different cryoprotectants (Me2SO, glycerol, and ethylene

Junji Mase; Hirokazu Mizuno; Kunihiko Okada; Kensuke Sakai; Daiki Mizuno; Kazutada Usami; Hideaki Kagami; Minoru Ueda

2006-01-01

374

Potentially lethal damage repair and its inhibitory effect of caffeine in two yolk sac tumor cell lines with different radiosensitivities  

Microsoft Academic Search

Purpose: In order to investigate the role of potentially lethal damage repair (PLDR) in cellular radiosensitivity, PLDR and its inhibitory effect by caffeine was examined. In addition, cell cycle distribution was also examined. Materials and methods: Two rat yolk sac tumor cell lines, NMT-1 and NMT-1R, with different radiosensitivities in vitro were used. The capacity for PLDR was examined using

Tetsuo Akimoto; Norio Mitsuhashi; Hiroko Matsumoto; Hideyuki Sakurai; Katsuya Maebayashi; Keiko Higuchi; Miwako Nozaki; Hideo Niibe

1999-01-01

375

Carbon Mineralization Potential in Soils of Different Habitats in the Semiarid Horqin Sandy Land: A Laboratory Experiment  

Microsoft Academic Search

Soil organic carbon mineralization potential in four different sandy habitats (shifting, semi-fixed, fixed sand dune, and interdunal lowland) and the effects of litter addition from shrubs and annual plants on soil microbial respiration were measured using a laboratory soil incubation experiment. Soil samples were collected from beneath and outside the canopies of shrubs in all habitats. Soils were incubated for

Yongzhong Su; Halin Zhao; Yulin Li; Jianyuan Cui

2004-01-01

376

The investigation of Toxocara canis eggs in coats of different dog breeds as a potential transmission route in human toxocariasis  

Microsoft Academic Search

This study was undertaken to determine the prevalence of Toxocara canis eggs on the coats of dogs (a potential etiological factor for human toxocariasis) and to see if there were mainly a dog breed and coat type effects for the presence of eggs on the coat. Hair samples were collected from the different breeds of 51 domestic pet dogs and

M. Aydenizöz-Özkayhan; B. B. Ya?c?; S. Erat

2008-01-01

377

Improving Students' Ability to Intuitively Infer Resistance from Magnitude of Current and Potential Difference Information: A Functional Learning Approach  

ERIC Educational Resources Information Center

The study examined the knowledge of the functional relations between potential difference, magnitude of current, and resistance among seventh graders, ninth graders, 11th graders (in technical schools), and college students. It also tested the efficiency of a learning device named "functional learning" derived from cognitive psychology on the…

Chasseigne, Gerard; Giraudeau, Caroline; Lafon, Peggy; Mullet, Etienne

2011-01-01

378

Potential Difference Applied to the Measurement of Small Fatigue Crack Growth at Notches in Ti-6Al-4V.  

National Technical Information Service (NTIS)

Several fatigue tests carried out on a Ti-6Al-4V alloy containing machined and polished notches to evaluate the growth of short cracks are described. The potential difference method is used, together with a surface replication technique, to characterize t...

M. D. Halliday A. F. Blom C. J. Beevers

1989-01-01

379

Selection for Unequal Densities of Sigma70 Promoter-like Signalsin Different Regions of Large Bacterial Genomes  

SciTech Connect

The evolutionary processes operating in the DNA regions that participate in the regulation of gene expression are poorly understood. In Escherichia coli, we have established a sequence pattern that distinguishes regulatory from nonregulatory regions. The density of promoter-like sequences, that are recognizable by RNA polymerase and may function as potential promoters, is high within regulatory regions, in contrast to coding regions and regions located between convergently-transcribed genes. Moreover, functional promoter sites identified experimentally are often found in the subregions of highest density of promoter-like signals, even when individual sites with higher binding affinity for RNA polymerase exist elsewhere within the regulatory region. In order to investigate the generality of this pattern, we have used position weight matrices describing the -35 and -10 promoter boxes of E. coli to search for these motifs in 43 additional genomes belonging to most established bacterial phyla, after specific calibration of the matrices according to the base composition of the noncoding regions of each genome. We have found that all bacterial species analyzed contain similar promoter-like motifs, and that, in most cases, these motifs follow the same genomic distribution observed in E. coli. Differential densities between regulatory and nonregulatory regions are detectable in most bacterial genomes, with the exception of those that have experienced evolutionary extreme genome reduction. Thus, the phylogenetic distribution of this pattern mirrors that of genes and other genomic features that require weak selection to be effective in order to persist. On this basis, we suggest that the loss of differential densities in the reduced genomes of host-restricted pathogens and symbionts is the outcome of a process of genome degradation resulting from the decreased efficiency of purifying selection in highly structured small populations. This implies that the differential distribution of promoter-like signals between regulatory and nonregulatory regions detected in large bacterial genomes confers a significant, although small, fitness advantage. This study paves the way for further identification of the specific types of selective constraints that affect the organization of regulatory regions and the overall distribution of promoter-like signals through more detailed comparative analyses among closely-related bacterial genomes.

Huerta, Araceli M.; Francino, M. Pilar; Morett, Enrique; Collado-Vides, Julio

2006-03-01

380

Analysis of Large-Scale Secondary Data in Higher Education Research: Potential Perils Associated with Complex Sampling Designs  

Microsoft Academic Search

Most large-scale secondary data sets used in higher education research (e.g., NPSAS or BPS) are constructed using complex survey sample designs where the population of interest is stratified on a number of dimensions and oversampled within certain of these strata. Moreover, these complex sample designs often cluster lower level units (e.g., students) within higher level units (e.g., colleges) to achieve

Scott L. Thomas; Ronald H. Heck

2001-01-01

381

On the factors behind large Labrador Sea tides during the last glacial cycle and the potential implications for Heinrich events  

Microsoft Academic Search

Labrador Sea (LS) tidal elevations over the last glacial cycle are investigated in a near-global numerical model that accurately captures the present-day tides. From ?65 ka to ?7 ka, the modeled elevations at the debouchement point of the Hudson Strait ice stream in the LS are exceptionally large, comparable to the largest elevations seen anywhere in the present-day ocean. New

Brian K. Arbic; Jerry X. Mitrovica; Douglas R. MacAyeal; Glenn A. Milne

2008-01-01

382

Measurements of spatial structure of plasma potential and density fluctuations by multichannel heavy ion beam probe on large helical device  

SciTech Connect

Heavy ion beam probe (HIBP) on large helical device is currently equipped with three channel detectors, which can observe three spatial points simultaneously inside the plasma with resolution of {approx}10 mm. The beam trajectories and observation point location are calculated numerically and optimized allowing for the identification of the mode structure in multichannel (up to 9) HIBP measurements. The calculations show that the radial and poloidal wavenumbers can be identified by proper changing and choosing of the beam energy and trajectory.

Ohshima, Shinsuke; Ido, Takeshi; Shimizu, Akihiro; Nishiura, Masaki; Nakano, Haruhisa [National Institute for Fusion Science, 322-6, Oroshi-cho, Toki, Gifu 509-5292 (Japan)

2008-10-15

383

Increased expression of the large GTPase dynamin 2 potentiates metastatic migration and invasion of pancreatic ductal carcinoma  

Microsoft Academic Search

Pancreatic ductal tumors invade local parenchyma and metastasize to distant organs. Src-mediated tyrosine kinase signaling pathways promote pancreatic ductal adenocarcinoma (PDAC) metastasis, though the molecular mechanisms supporting this invasive process are poorly understood and represent important and novel therapeutic targets. The large GTPase Dynamin 2 (Dyn2), a Src-kinase substrate, regulates membrane–cytoskeletal dynamics although it is yet to be defined if

R D Eppinga; E W Krueger; S G Weller; L Zhang; H Cao; M A McNiven

2012-01-01

384

Hemispheric Lateralization of Event-Related Brain Potentials in Different Processing Phases during Unimanual Finger Movements  

Microsoft Academic Search

Previous functional MRI and brain electrophysiology studies have studied the left-right differences during the tapping tasks and found that the activation of left hemisphere was more significant than that of right hemisphere. In this study, we wanted to delineate this lateralization phenomenon not only i n the execution phase but also in other processing phases, such as early visual, pre-execut

Ling-Fu Meng; Chiu-Ping Lu; Yi-Wen Li

2008-01-01

385

Hemispheric Differences in Strong versus Weak Semantic Priming: Evidence from Event-Related Brain Potentials  

ERIC Educational Resources Information Center

|Goals: Research with lateralized word presentation has suggested that strong ("close") and weak ("remote") semantic associates are processed differently in the left and right cerebral hemispheres [e.g., Beeman, M. j., & Chiarello, C. (1998). Complementary right- and left-hemisphere language comprehension. "Current Directions in Psychological…

Frishkoff, Gwen A.

2007-01-01

386

Hemispheric Differences in Strong versus Weak Semantic Priming: Evidence from Event-Related Brain Potentials  

ERIC Educational Resources Information Center

Goals: Research with lateralized word presentation has suggested that strong ("close") and weak ("remote") semantic associates are processed differently in the left and right cerebral hemispheres [e.g., Beeman, M. j., & Chiarello, C. (1998). Complementary right- and left-hemisphere language comprehension. "Current Directions in Psychological…

Frishkoff, Gwen A.

2007-01-01

387

Difference, Ambiguity and Potential for Learning--Local Communities Working in Partnership with Local Government.  

ERIC Educational Resources Information Center

|An action learning project for neighborhood regeneration in Coventry, England, showed that differences of power and viewpoint were inevitable and essential. More open networks enabling communication among community groups were needed. Funding for community networking needed to go beyond short-term projects supported by the current policy agenda.…

Blaxter, Loraine; Farnell, Richard; Watts, Jane

2003-01-01

388

Evaluation of antimicrobial potential of different extracts of Solanum xanthocarpum Schrad. and Wendl  

Microsoft Academic Search

Antimicrobial activity of the aqueous and organic solvent extracts of different parts (roots, stems, leaves and fruits) of Solanum xanthocarpum Schrad. and Wendl. against Gram-positive and Gram- negative bacteria and a fungus was evaluated. Plant extracts of S. xanthocarpum were prepared in distilled water and in organic solvents, viz. ethanol, benzene, acetone and methanol. Agar well diffusion technique was used

Raj K. Salar; Chaudhary Devi

389

Early interactions between leukocytes and three different potentially bioactive titanium surface modifications.  

PubMed

The aim of the present study was to compare the early interactions between leukocytes and three different surface modifications, suggested as bioactive. Blasted titanium discs were modified by alkali and heat treatment, sodium fluoride treatment, or hydroxyapatite coating. A number of these discs were also immersed in simulated body fluid (SBF) for a week, a treatment which yielded high levels of calcium and phosphate on each surface type. The specimens were exposed for human venous blood for 32 minutes and the respiratory burst response was measured in terms of reactive oxygen species with a luminometer, and coverage of viable cells with a fluorescence microscope after staining steps. The topography, morphology, and chemistry of the surfaces were evaluated with optical interferometry and scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). A high respiratory burst response was found for HA coated titanium in comparison with the other surface groups (p < 0.0005). The SBF immersion resulted in an increased respiratory burst response (p < 0.0005) and removed statistically significant differences between the surface groups. Thus, the results in the present study indicate that different titanium surface modifications influence the early inflammatory response differently, and that calcium phosphate compounds increase the inflammatory response. PMID:21442746

Arvidsson, Anna; Malmberg, Per; Kjellin, Per; Currie, Fredrik; Arvidsson, Martin; Franke Stenport, Victoria

2011-03-25

390

Oncogenic NRAS, KRAS, and HRAS Exhibit Different Leukemogenic Potentials in Mice  

Microsoft Academic Search

RAS proteins are small GTPases that play a central role in transducing signals that regulate cell proliferation, survival, and differentiation. The RAS proteins interact with a common set of activators and effectors; however, they associate with different microdomains of the plasma membrane as well as other endomembranes and are capable of generating distinct signal outputs. Mutations that result in constitutive

Chaitali Parikh; Ramesh Subrahmanyam; Ruibao Ren

2007-01-01

391

Bladder substitutes controlled by the anal sphincter: A comparison of the different absorption potentials  

SciTech Connect

A comparative study of the absorption potentials of the simple rectal bladder (10 patients), modified rectal bladder (20) and ureterosigmoidostomy (10) was done with intrarectal instillation of 22sodium. Results indicate that absorption is significantly greater among patients with ureterosigmoidostomy. The emptying patterns of ureterosigmoidostomy and the modified rectal bladder were also studied by ascending scintigraphy with 99mtechnetium. Evidence was provided that in cases with ureterosigmoidostomy the isotope is distributed throughout the entire colon. These studies proved the role of the colorectal valve in preventing reflux of urine from the rectum to the proximal colon. Consequently, the surface area of colonic mucosa exposed to urine is decreased and the rate of reabsorption is limited.

el-Mekresh, M.M.; Shehab el-Din, A.B.; Fayed, S.M.; Brevinge, H.; Kock, N.G.; Ghoneim, M.A. (Department of Urology, Urology-Nephrology Center, Mansoura (Egypt))

1991-10-01

392

Strains of the soil fungus Mortierella show different degradation potentials for the phenylurea herbicide diuron.  

PubMed

Microbial pesticide degradation studies have until now mainly focused on bacteria, although fungi have also been shown to degrade pesticides. In this study we clarify the background for the ability of the common soil fungus Mortierella to degrade the phenylurea herbicide diuron. Diuron degradation potentials of five Mortierella strains were compared, and the role of carbon and nitrogen for the degradation process was investigated. Results showed that the ability to degrade diuron varied greatly among the Mortierella strains tested, and the strains able to degrade diuron were closely related. Degradation of diuron was fastest in carbon and nitrogen rich media while suboptimal nutrient levels restricted degradation, making it unlikely that Mortierella utilize diuron as carbon or nitrogen sources. Degradation kinetics showed that diuron degradation was followed by formation of the metabolites 1-(3,4-dichlorophenyl)-3-methylurea, 1-(3,4-dichlorophenyl)urea and an hitherto unknown metabolite suggested to be 1-(3,4-dichlorophenyl)-3-methylideneurea. PMID:23361127

Ellegaard-Jensen, Lea; Aamand, Jens; Kragelund, Birthe B; Johnsen, Anders H; Rosendahl, Søren

2013-01-30

393

Presence and potential of cell free DNA in different types of forensic samples.  

PubMed

Extracellular or cell free DNA has been found to exist in many biological media such as blood and saliva. To check whether cell free DNA is present in the supernatant which is normally discarded during several DNA extraction processes, such as Chelex(®) extraction, DNA profiles of cell pellet and concentrated supernatant from 30 artificial case like samples and from 100 real forensic samples were compared. Presence of cell free DNA was shown in all investigated sample types. Moreover, in some samples additional alleles, not detected during analysis of the cell pellet, were detected, offering valuable information which would normally have been discarded together with the supernatant. The results presented here indicate that cell free DNA deserves further consideration since it has the potential to increase the DNA yield in forensic casework samples in general and in contact traces in particular. PMID:23318134

Vandewoestyne, Mado; Van Hoofstat, David; Franssen, Aimée; Van Nieuwerburgh, Filip; Deforce, Dieter

2013-01-11

394

Effect of compost, nitrogen salts, and NPK fertilizers on methane oxidation potential at different temperatures.  

PubMed

The effects of compost, nitrogen salts, and nitrogen-phosphorous-potassium (NPK) fertilizers on the methane oxidation potential (MOP) of landfill cover soil at various temperatures were assessed. For this, we used batch assays conducted at 5°C, 15°C, and 25°C with microcosms containing landfill cover soil slurries amended with these elements. Results indicated variable impacts dependent on the type of amendment and the incubation temperature. For a given incubation temperature, MOP varied from one compost to another and with the amount of compost added, except for the shrimp/peat compost. With this latter compost, independent of the amount, MOP values remained similar and were significantly higher than those obtained with other composts. Amendment with most of the tested nitrogen salts led to similar improvements in methanotrophic activity, except for urea. MOP with NPK fertilizer addition was amongst the highest in this study; the minimum value obtained with NPK (20-0-20) suggested the importance of P for methanotrophs. MOP generally increased with temperature, and nutrient limitation became less important at higher temperatures. Overall, at each of the three temperatures tested, MOP with NPK fertilizer amendments provided the best results and was comparable to those observed with the addition of the shrimp/peat compost. The results of this study provide the first evidence of the following: (1) compost addition to improve methanotrophic activity in a landfill cover soil should consider the amount and type of compost used and (2) the importance of using NPK fertilizers rather than nitrogen salts, in enhancing this activity, primarily at low temperatures. One can also consider the potential beneficial impact of adding these elements to enhance plant growth, which is an advantage for MOP. PMID:21894478

Jugnia, Louis-B; Mottiar, Yaseen; Djuikom, Euphrasie; Cabral, Alexandre R; Greer, Charles W

2011-09-06

395

Pattern of cell kinetics in colorectal mucosa of patients with different types of adenomatous polyps of the large bowel  

SciTech Connect

It is generally accepted that adenomatous polyps represent the natural precursor of many colorectal malignancies. The sequence, however, which leads from a normally appearing mucosa to cancer is complex and involves many steps, including a hyperproliferative mucosa with an upward expansion of the replicative compartment. The current study evaluates cell replication in normal colorectal mucosa of patients with adenomatous polyps of various types and relates the observed findings to the main clinical and morphologic features of adenomas. Forty-four patients with polyps and 27 controls entered the study. Samples of colorectal mucosa were taken at endoscopy and cell replication was evaluated with a standard autoradiographic procedure. Cell replication was expressed as labeling index (LI), in the whole crypt and in each of the five longitudinal compartments in which the crypts were divided. Total LI and LI per crypt compartment were significantly higher (P less than 0.02 and P less than 0.01, respectively) than in controls. There was no appreciable difference of LI values between patients with single or multiple, tubular or tubulovillous, small or large adenomas, but in all of these subgroups LI was significantly higher than in controls. In conclusion, in normally appearing colorectal mucosa of patients with adenomatous polyps there was a significant increase of cell replication and a marked upward expansion of the proliferative zone; these changes were more evident in the left colon and in the rectum. Finally, cell replication did not seem to be related to the number of polyps, to the most common histotypes, or to the pattern of recurrence.

Roncucci, L.; Scalmati, A.; Ponz de Leon, M. (Colorectal Cancer Study Group, University of Modena (Italy))

1991-08-15

396

Antimicrobial efficacy and irrigating potential of irrigation solutions using different activation methods.  

PubMed

The objective of this in vitro study was to establish the antimicrobial efficacy and the effect of different activation methods on the smear layer at the coronal level of straight root canals of four different root canal irrigation solutions. The four irrigation solutions were 3.5% sodium hypochlorite liquid (NaOCl), 2% sodium hypochlorite gel, chlorhexidine gluconate liquid and a mixture of 100 mg doxycycline capsules with 2 ml sterile water. ANTIMICROBIAL EFFECTS: The surfaces of four agar plates were inoculated with Enterococcus faecalis and divided into four equal quadrants. Ten microlitres of each test solution was dispensed onto the four filter paper disks on each agar plate. The antibacterial activity of materials was apparent from circular clear inhibition zones forming around the filtration paper. The diameters of these inhibition zones were measured using a micrometer gauge. EFFECT ON SMEAR LAYER: Access cavities were prepared on fifty, extracted, single rooted, human teeth and the root canals prepared with rotary files. The teeth were randomly divided into five groups (n = 10) and each group irrigated with a different irrigation solution. Different activation methods were used in the coronal portion of each root canal. The solutions were activated in the canals using one of the following methods: a 30 gauge needle (Control), a sonic scaler tip, and a rotary brush. After sampling, the roots of the treated teeth were fractured and prepared for Scanning Electron Microscopy (SEM) according to standard methods. The one-way ANOVA test was used to determine whether there were any statistical significant differences between the different groups. The average zones of inhibition for 3.5% NaOCl, 2% NaOCl, 2.5% chlorhexidine and doxycycline were 2.7mm, 2.0 mm, 11.2 mm and 12.4 mm respectively. Sterile water, 3.5% NaOCl and 2% NaOCl had no significant effect on the smear layer. However, when chlorhexidine and doxycycline solutions were activated with a rotary brush, 90 and 80 per cent of the observed surfaces were free of smear layer respectively. Doxycyline and 2.5% chlorhexidine demonstrated the highest antimicrobial activity against Enterococcus faecalis and removed most of the smear layer when the solutions were activated with a rotary brush. PMID:19517856

van der Vyver, P J; Botha, F S; Herbst, D; Ismail, M

2009-03-01

397

Numerical Simulation on Structural Stability of Different Types of Surge Shaft - Illustrated with a Case Study of a Large Scale Underground Complex  

Microsoft Academic Search

The long gallery type and cylinder type are the two main types of surge shaft in large scale hydropower underground complexes. The assessment method using FEM calculation results to analyze the structural stability of different types of surge shaft in large scale underground complexes is put forward. Firstly, the general FEM procedure to simulate underground excavation is proposed. Then, the

Yuting Zhang; Ming Xiao; Juntao Chen

2009-01-01

398

Potential yields and properties of oil from the hydrothermal liquefaction of microalgae with different biochemical content  

Microsoft Academic Search

A range of model biochemical components, microalgae and cyanobacteria with different biochemical contents have been liquefied under hydrothermal conditions at 350°C, ?200bar in water, 1M Na2CO3 and 1M formic acid. The model compounds include albumin and a soya protein, starch and glucose, the triglyceride from sunflower oil and two amino acids. Microalgae include Chlorella vulgaris,Nannochloropsis occulata and Porphyridium cruentum and

P. Biller; A. B. Ross

2011-01-01

399

Spleen and liver dendritic cells differ in their tolerogenic and cytokine induction potential.  

PubMed

Dendritic cells (DCs) play an important role in induction of cellular immune responses. It seems that DCs that reside in different organs may be distinct in their ability to induce immune responses. This study was done to address the differences between spleen and liver DCs in induction of immune response and/or tolerance. CD11c+ DCs were separated from the liver and spleen of C57BL/6 mice and pulsed with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55. 6105 MOG35-55 pulsed spleen or liver DCs were injected in foot pad of different groups of mice. Control groups received unpulsed DCs. After 5 days, the mononuclear cells (MNCs) of the regional lymph nodes were isolated from immunized mice for cytokine assays and lymphocyte transformation test. To study the immunologic or tolerogenic effects of DCs, three weeks after immunization of mice with MOG pulsed liver or spleen DCs, experimental autoimmune encephalomyelitis (EAE) was induced in DC-immunized mice by injection of MOG along with complete Freund's adjuvant. Our results showed that spleen DCs were more potent in stimulating lymph node T cells as illustrated in lymphocyte transformation test. Moreover IL-10 production was higher in mice immunized with liver DCs compared with those immunized with splenic DCs (p=0.017). However, no significant difference in IFN-? production was observed between two groups. We also found that liver DCs+MOG immunized mice displayed a significantly delayed disease onset compared with spleen DCs+MOG immunized mice and the control groups. The disease score was also milder in liver DCs immunized mice compared with other groups. It seems that the higher IL-10 production induced by the liver DCs may be one of the main factors in down regulation of immune responses in this organ. It can be concluded also that the liver DCs may inhibit the progress of EAE by shifting the cytokines profile. PMID:21891822

Mosayebi, Ghasem; Moazzeni, Seyed Mohammad

2011-09-01

400

Evaluation of oxidative stress responses and neurotoxicity potential of diazinon in different tissues of Cyprinus carpio  

Microsoft Academic Search

Toxicity of organophosphorus insecticides is mainly due to the inhibition of acetylcholinesterase, but, oxidative stress may be involved in the toxicity of this pesticides. Therefore, it was investigated whether diazinon, a commonly used organophosphate, may induce oxidative stress and cholinesterase inhibition in different tissues of Cyprinus carpio. Sublethal concentrations of diazinon (0.0036, 0.018 and 0.036ppb) were administired to C. carpio

Elif Özcan Oruç; Demet Usta

2007-01-01

401

Proficiency differences in syntactic processing of monolingual native speakers indexed by event-related potentials.  

PubMed

Although anecdotally there appear to be differences in the way native speakers use and comprehend their native language, most empirical investigations of language processing study university students and none have studied differences in language proficiency, which may be independent of resource limitations such as working memory span. We examined differences in language proficiency in adult monolingual native speakers of English using an ERP paradigm. ERPs were recorded to insertion phrase structure violations in naturally spoken English sentences. Participants recruited from a wide spectrum of society were given standardized measures of English language proficiency, and two complementary ERP analyses were performed. In between-groups analyses, participants were divided on the basis of standardized proficiency scores into lower proficiency and higher proficiency groups. Compared with lower proficiency participants, higher proficiency participants showed an early anterior negativity that was more focal, both spatially and temporally, and a larger and more widely distributed positivity (P600) to violations. In correlational analyses, we used a wide spectrum of proficiency scores to examine the degree to which individual proficiency scores correlated with individual neural responses to syntactic violations in regions and time windows identified in the between-groups analyses. This approach also used partial correlation analyses to control for possible confounding variables. These analyses provided evidence for the effects of proficiency that converged with the between-groups analyses. These results suggest that adult monolingual native speakers of English who vary in language proficiency differ in the recruitment of syntactic processes that are hypothesized to be at least in part automatic as well as of those thought to be more controlled. These results also suggest that to fully characterize neural organization for language in native speakers it is necessary to include participants of varying proficiency. PMID:19925188

Pakulak, Eric; Neville, Helen J

2010-12-01

402

Larvicidal potential of different solvent extracts and oleanolic acid derivative from Coccinia indica against vector mosquitoes  

Microsoft Academic Search

The mosquito larvicidal activities of different solvent extracts (chloroform, ethyl acetate, and methanol) from the leaves of Coccinia indica were studied. Among the extracts tested, the methanol extract showed the highest larvicidal activity against early fourth instar larvae of Culex quinquefasciatus (LC50?=?142?mg?L), Aedes aegypti (LC50?=?158?mg?L) and Anopheles stephensi (LC50?=?161?mg?L) after 24?h of exposure period. The lowest larval mortality was observed

A. Senthilkumar; S. N. Tikar; N. Gopalan; P. Sundaramoorthy; V. Venkatesalu

2012-01-01

403

Potential population growth and harmful effects on humans from bed bug populations exposed to different feeding regimes.  

PubMed

Effects of host availability and feeding period on bed bugs, Cimex lectularius (L.) (Hemiptera: Cimicidae), were measured. Population growth and the potential harmful effect of bed bug populations on human hosts were modelled. Bloodmeal sizes were affected by both feeding length and frequency, with >2-fold difference between insects fed daily or weekly. Blood consumption increased >2-fold between bed bugs fed occasionally and often, and 1.5-fold between occasional and daily feeding. Bed bugs fed more often than once a week, potentially every 2-4 days. Egg production was associated with nutrition, being strongly correlated with blood consumption in the previous week. Bed bug populations can grow under different feeding regimes and are hard to control with <80% mortality. Bed bugs can survive and grow even in locations with a limited blood supply, where bed bug persistence may be important for the continual spread of populations. Persistence in non-traditional locations and a potential association with human pathogens increase the health risks of bed bugs. Potential blood loss as a result of a bed bug can have serious consequences because uncontrolled populations can reach harmful levels in 3-8 months. The reproduction potential of bed bug populations suggests serious consequences to human health and the need for efficacious control measures. PMID:23046478

Pereira, R M; Taylor, A S; Lehnert, M P; Koehler, P G

2012-10-10

404

Slow fluorescent indicators of membrane potential: a survey of different approaches to probe response analysis.  

PubMed

Basic tenets related to the use of three main classes of potentiometric redistribution fluorescent dyes (carbocyanines, oxonols, and rhodamines) are discussed in detail. They include the structure/function relationship, formation of nonfluorescent (H-type) and fluorescent (J-type) dimers and higher aggregates, probe partitioning between membranes and medium and binding to membranes and intracellular components (with attendant changes in absorption and emission spectra, fluorescence quantum yield and lifetime). The crucial importance of suitable probe-to-cell concentration ratio and selection of optimum monitored fluorescence wavelength is illustrated in schematic diagrams and possible artifacts or puzzling results stemming from faulty experimental protocol are pointed out. Special attention is paid to procedures used for probe-response calibration (potential clamping by potassium in the presence of valinomycin, use of gramicidin D in combination with N-methylglucamine, activation of Ca-dependent K-channels by A23187, the null-point technique). Among other problems treated are dye toxicity, interaction with mitochondria and other organelles, and possible effects of intracellular pH and the quantity of cytosolic proteins and/or RNA on probe response. Individual techniques using redistribution dyes (fluorescence measurements in cuvettes, flow cytometry and microfluorimetry of individual cells including fluorescence confocal microscopy) are discussed in terms of reliability, limitations and drawbacks, and selection of suitable probes. Up-to-date examples of application of slow dyes illustrate the broad range of problems in which these probes can be used. PMID:8691353

Plásek, J; Sigler, K

1996-04-01

405

Pharmacological differences of endothelin receptors-mediated modulation in cultured interstitial cells of Cajal from the murine small and large intestine.  

PubMed

Interstitial cells of Cajal (ICCs) are pacemaker cells that activate the periodic spontaneous depolarization (pacemaker potentials) responsible for the production of slow waves in gastrointestinal smooth muscle. Under current clamping, ICCs had a mean resting membrane potential of -58 ± 3 mV and externally applied ET produced membrane depolarization in a dosedependent manner. These effects were reduced by intracellular GDP beta S. A comparison of the concentration-dependent membrane depolarizations on pacemaker potentials to ET-1, ET-2 and ET-3 showed a rank order of potency ET-1?ET-2?ET-3 in cultured murine small intestinal ICCs. The pretreatment with Ca(2+)-free solution and thapsigargin, a Ca(2+)-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker potentials and suppressed the ET-1 induced membrane depolarizations. Chelerythrine and calphostin C, protein kinase C inhibitors or naproxen, an inhibitor of cyclooxygenase, did not block the ET-1 induced effects on pacemaker potentials. Pretreatment with BQ-123 (ET(A )receptor antagonist) or BQ-788 (ET(B )receptor antagonist) blocked the ET-1 induced effects on pacemaker potentials in cultured murine small intestinal ICCs. However, pretreatment with BQ-788 selectively did not block the ET-1 induced effects on pacemaker potentials in cultured murine large intestinal ICCs. Also, only externally applied selective ET(B )receptor agonist, IRL 1620 did not show any influence on pacemaker potentials in cultured murine large intestine ICCs. RT-PCR results indicated the presence of the ET(A )and ET(B )receptor in ICCs. These results suggested that ET-1 modulates pacemaker potentials through ET(A )and ET(B )receptor activation in murine small intestinal ICCs and ET(A )receptor activation in murine large intestinal ICCs by external Ca(2+) influx and internal Ca(2+) release via protein kinase C or cyclooxygenase-independent mechanism. Therefore, the ICCs are targets for ET and their interaction can affect intestinal motility. PMID:22739356

Kim, Byung Joo; Chang, In Youb; So, Insuk

2012-06-29

406

Different Potential of C-Type Lectin-Mediated Entry between Marburg Virus Strains?  

PubMed Central

The glycoproteins (GPs) of filoviruses are responsible for virus entry into cells. It is known that GP interacts with cellular C-type lectins for virus attachment to cells. Since primary target cells of filoviruses express C-type lectins, C-type lectin-mediated entry is thought to be a possible determinant of virus tropism and pathogenesis. We compared the efficiency of C-type lectin-mediated entry between Marburg virus strains Angola and Musoke by using a vesicular stomatitis virus (VSV) pseudotype system. VSV pseudotyped with Angola GP (VSV-Angola) infected K562 cells expressing the C-type lectin, human macrophage galactose-type C-type lectin (hMGL), or dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN) more efficiently than VSV pseudotyped with Musoke GP (VSV-Musoke). Unexpectedly, the binding affinity of the C-type lectins to the carbohydrates on GPs did not correlate with the different efficiency of C-type lectin-mediated entry. Site-directed mutagenesis identified the amino acid at position 547, which switched the efficiency of C-type lectin-mediated entry. In a three-dimensional model of GP, this amino acid was in close proximity to the putative site of cathepsin processing. Interestingly, the cathepsin inhibitors reduced the infectivity of VSV-Angola less efficiently than that of VSV-Musoke in C-type lectin-expressing K562 cells, whereas only a limited difference was found in control cells. The amino acid at position 547 was critical for the different effects of the inhibitors on the virus infectivities. These results suggest that the efficiency of C-type lectin-mediated entry of filoviruses is controlled not only by binding affinity between C-type lectins and GP but also by mechanisms underlying endosomal entry, such as proteolytic processing by the cathepsins.

Matsuno, Keita; Kishida, Noriko; Usami, Katsuaki; Igarashi, Manabu; Yoshida, Reiko; Nakayama, Eri; Shimojima, Masayuki; Feldmann, Heinz; Irimura, Tatsuro; Kawaoka, Yoshihiro; Takada,