Search Results - (Author, Cooperation:T. McMahon)

2014-12-18

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Actins/metabolism ; Acyltransferases/*metabolism ; Cell Line ; Clathrin ; Dynamins/metabolism ; *Endocytosis ; Humans ; Ligands ; Phosphatidylinositol Phosphates/metabolism ; Pseudopodia/metabolism ; Receptor Protein-Tyrosine Kinases/metabolism ; Receptors, G-Protein-Coupled/metabolism ; Receptors, Interleukin-2/metabolism ; Signal Transduction ; Time Factors

2014-12-18

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Actins/metabolism ; Acyltransferases/*metabolism ; Animals ; Cell Line ; Cell Membrane/*metabolism ; Cholera Toxin/metabolism ; Clathrin ; Dynamins/metabolism ; *Endocytosis ; Humans ; Rats ; Shiga Toxin/metabolism

2013-01-04

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Anxiety/genetics ; Behavior, Animal ; Benzophenanthridines/pharmacology ; Cocaine ; Conditioning, Classical ; Cues ; Exons/genetics ; Fear ; Female ; *Gene Deletion ; Male ; Memory/*physiology ; Mice ; Protein Kinase C/analysis/*deficiency/*genetics/immunology

1089-7550

AIP Digital Archive

Physics

The concept of electronic doping is used to explain unexpectedly large values of the diode quality factor (exceeding two) and supralinearity which is sometimes observed in amorphous silicon p-i-n-type diodes and materials, respectively. This suggests the presence of an extra set of defect states in lightly boron-doped films with a capture rate for electrons which is much larger than that of the inherent defect states. We also report that for high-quality undoped intrinsic layers, the photoconductivity versus intensity behavior exhibits sublinear power dependence which increases with intensity in distinct contrast to the previously reported results. We provide a self-consistent model which is able to explain the above observations.

Electronic Resource

1365-2494

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

A hay drying model (HAYDMO) which predicts the moisture content of pasture hay is described. It uses multiple regression equations based on field drying experiments with conditioned and unconditioned hay and predicts hourly changes in moisture content for both day and night and also those due to rain. The model can be used with three different combinations of weather, including hourly wet and dry bulb temperatures, radiation, wind speed and rainfall. Testing HAYDMO revealed a satisfactory agreement between predicted and observed moisture contents

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Steady-state photoconductivity, sub-band-gap absorption and electron spin resonance (ESR) measurements were carried out on annealed and light soaked intrinsic hydrogenated amorphous silicon (a-Si:H) films. The experimental results were modeled using detailed numerical analysis. The defect densities derived from the sub-band-gap absorption in the light soaked films were correlated with the ESR spin densities. Self-consistent fitting of the data was obtained using a gap state distribution which consists of positively charged defect states above, negatively charged defect states below and neutral defect states at about the midgap. Both the annealed and the light degraded states are modeled using the same gap states which increase upon light soaking and have a slight increase in the ratio of the neutral to charged defect densities. These results on intrinsic a-Si:H are consistent with proposed charged defect models and clearly indicate the importance of charged defect states in determining sub-band-gap absorption as well as its correlation with neutral dangling bonds.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

We performed a detailed study of electron spin resonance (ESR) spectra of porous silicon (PS) samples at different stages of treatment and with different porosities. In addition to the commonly observed Pb0-like dangling bond, results of curve fitting to our ESR spectra show that a Pb1-like center, similar to the Pb1 center observed at the (100) crystalline-Si/SiO2 interface, appears in the PS nanostructure. The ratio of the number of Pb1-like centers to that of Pb0-like centers is related to the PS porosity. Remote hydrogen plasma processing of the annealed PS does not change the ratio significantly, although the total numbers of Pb0-like and Pb1-like centers are reduced and photoluminescence efficiency is improved.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

We find the equilibrium temperature for intrinsic glow discharge amorphous silicon to be 195–200 °C. Defects left behind after fast cooling result in a temperature-dependent dc photoconductivity which shows small differences in the tail state recombination kinetics when compared to defects left behind in the same number after light soaking. Finally anneal kinetics of fast cool defects follow neither singly activated, mono-, nor bimolecular kinetics with a temperature dependence indicating activation energies from 1.0 to 1.4 eV. Unlike the distribution of defects left behind in similar number as a result of light soaking at room temperature, the distribution of defects resulting from fast cooling from higher temperature is shifted to higher energies and requires much longer anneal times.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

We compare the electron spin resonance (ESR) signal of the dangling bond in porous silicon (PS) layers, produced by electrochemical etching, to the ESR signal from hydrogenated amorphous Si(a-Si:H) films. The anisotropy of the ESR signal from PS showed g values varying as for the Pb Si/SiO2 interface dangling bond. The g value varies from g(parallel)=2.0020 to g⊥=2.0080 with an inhomogeneously broadened line width increasing from 1.8 to 3.8 G. An ESR powder line, with superhyperfine and strain broadening intrinsic to PS, has more anisotropy in g(parallel)−g⊥ and less inhomogeneous broadening than does the dangling bond line in a-Si:H. No evidence was seen for light-induced metastability on a H-passivated PS film.

Electronic Resource

1752-1688

Blackwell Publishing Journal Backfiles 1879-2005

Architecture, Civil Engineering, Surveying

Geography

: A procedure for computing the benefit/cost ratio of a hydrometric network is outlined. It consists of two steps: firstly, establishing a relationship between hydrometric station density and error in hydrologic parameters and, secondly, relating hydrologic eror to changes in project cost. The procedure was applied to both the whole Canadian hydrometric network and the provincial networks.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Laboratory feeding trials were conducted to determine how light intensity affects foraging success by the visual piscivore, the largemouth bass (Micropterus salmoides). Foraging success was greater than 95% at light levels ranging from low intensity daylight (2.43 × 102 lx) to moonlight (3 × 10−3 lx), but declined significantly to 62% at starlight (2 × 10−4 lx) and near 0% in total darkness. Over a range of low to high water clarities (0.5, 2.0, and 4.0 m Secchi depth), estimated depth limits for feeding during the day ranged between 5.5 to 44 m and from 1.6 to 13 m at night during a full moon. At starlight, light intensity rapidly attenuated to a level below the feeding threshold within 0.5 m of the surface at all water clarities. The depth of the water column available for feeding in low clarity water (0.5 m Secchi) was 67 and 75% less than at moderate (2.0 m Secchi) and high (4.0 m Secchi) water clarities. The findings illustrate how differences in the light environment can have important ramifications for predator-prey interactions.

Electronic Resource

1365-2427

Blackwell Publishing Journal Backfiles 1879-2005

Biology

1. Droughts are not easily defined other than by culturally driven judgements about the extent and nature of impact. Natural ecosystems are adapted to the magnitude and frequency of dry periods and these are instrumental in controlling the long term functioning of these systems.2. In unregulated rivers, low flows are derived from water in long-term storage in the catchment, commonly as shallow groundwater. Four types of low flow sequences are evident for representative rivers from each of the seven flow regime zones in Australia and an arid zone stream: perennial streams with low annual flow variability that have seasonal low flows but do not cease to flow; perennial streams with high annual variability that cease to flow in extreme years; ephemeral streams that regularly cease to flow in the dry season; and arid zone streams with long and erratic periods of no flow.3. Although Australian rivers record runs of consecutive years of low flows longer than would be expected theoretically, the departures from the expected are not statistically significant. Trends and quasi-cycles in sequences of low-flow years are observed over decadal time scales.4. Examples of the effects of river regulation on low flows in southern Australia indicate that, while in detail the impacts of regulation vary, in general regulation mitigates the severity of low flows.5. It is our contention that the indigenous biota of Australian rivers are adapted to the naturally occurring low flow conditions and that, while there is considerable scientific interest in the effects of climate change on stream ecology, such studies have little practical relevance for the management of indigenous biota in unregulated rivers.6. The changes brought about by the regulation of rivers are much more rapid and dramatic than those which might occur as a result of climate change and it is possible to develop management procedures to mitigate them. In regulated rivers, the real problem may be ‘anti-droughts’– the removal of significant natural low-flow events from the flow pattern.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

We discuss the procedure of calculating the density of states in the gap for amorphous silicon by integrating the excess sub-band-gap absorption. We show that in general the proportionality coefficient between the density of states and the integrated sub-band-gap absorption is not unique. The sum rule has been used improperly since integration of the excess subgap absorption is terminated either at a fixed energy or at an energy which does not include all optical transitions to the conduction band. We estimate the errors that can arise from this procedure.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Gas phase proton transfer equilibria involving compounds in the basicity regime near CO have been examined using pulsed electron beam high pressure mass spectrometric techniques. Using the well established proton affinity of C2H4 of 162.6 kcal mol−1 as a reference standard a new proton affinity for CO of 145.6 kcal mol−1 is established. The disagreement between this value and those obtained by photoionization mass spectrometric appearance potential measurements of HCO+ ions from compounds of the type HCOR is interpreted as being due to an activation energy barrier for the reverse process: HCO++R (overdot)→HCOR+. This barrier results from the significant geometry change involved in HCO+ formation. Correlations of proton affinity of O1S binding energies have been used to establish the proton affinity of the oxygen site of CO as 109 kcal mol−1. This result implies that HOC+ can be readily formed by reaction of H+3 with CO in interstellar clouds.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

As basilisk lizards (Basiliscus basiliscus) and shore birds run along the water surface they support their body weight by slapping and stroking into the water with their feet. The foot motions exploit the hydrodynamic forces of low-speed water entry. To determine the forces that are produced during water entry at low speeds, we measured directly the impact and drag forces for disks dropped into water at low Froude numbers (u2/gr=1–80). Also, we measured the period during which the air cavity behind the disk remains open to atmospheric air. We found that the force impulse produced during the impact phase is due to the acceleration of the virtual mass of fluid associated with a disk at the water surface. A dimensionless virtual mass M, defined as M=mvirtual/(4/3)πρr3, has a value near 1/π for disks. After impact, as penetration depth of the disk increases, the drag force can rise by as much as 76% even though the downward velocity is steady. However, a dimensionless force which includes the contribution from hydrostatic pressure [CD*=Drag(t)/(ρSgh(t)+0.5ρSu2)] takes a constant value near 0.7 regardless of disk size, speed, or cavity depth. Over the entire range of disk sizes and velocities, the period between impact and cavity closure, Tseal, can be described by a single value of dimensionless time, τ=Tseal(g/r)0.5, near 2.3. We con- clude that the fundamental phenomena associated with the low-speed water entry of a disk can be characterized by three dimensionless numbers (M, CD*, and τ). © 1996 American Institute of Physics.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Degree of silvering (colouration) is often used as an index of the degree of smoltification in salmonids. To judge the reliability of silvering as an indicator of migratory readiness, we examined the silvering of wild coho salmon, Oncorhynchus kisutch, smolts upon entry into the Carnation Creek, British Columbia, estuary. Silvering of migrants was greater in larger fish and increased over the course of the migratory period. Photoperiod appeared to account for most of the observed increase in silvering over time; increased silvering was not correlated with temperature or lunar phase. Overall, 50% of seaward migrants were completely silvered, 45% were in a transitional phase, and 5% still retained colouration characteristics of parr. Colouration thus appears to have limited utility as a reliable indicator of migratory readiness. Our findings suggest that estuarine residence is important for completion of parr-smolt transformation and that acclimation of hatchery smolts in brackish water prior to sea water entry may enhance their survival.

Electronic Resource

0009-9120

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Medicine

Electronic Resource

0009-9120

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Medicine

Electronic Resource

1439-0426

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

The marine aquaculture industry in Ireland has developed steadily since the early 1980s and currently employs approximately 2500 people with an output valued at some IR£60 (∈76) million. The main species produced are Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), mussels (Mytilus edulis), the Japanese oyster (Crassostrea gigas), the native flat oyster (Ostrea edulis), scallops (Pecten maximus) and clams (Tapes semideccusata). In Ireland, the Department of the Marine and Natural Resources is the sole licensing and regulatory authority for marine aquaculture. Details of the licensing requirements and licence application procedures for both finfish and shellfish farming are presented. The role of the independent Aquaculture Licences Appeals Board is described. In the case of shellfish production, no specific environmental standards have been established and therefore no specific monitoring requirements have been set down. This situation is currently under review. In the case of the production of salmon, environmental standards and monitoring requirements have evolved with time and details of the monitoring programmes focusing on sea lice, impact on the benthos and water column nutrient concentrations are described. Additional monitoring programmes required under various EU Directives are also presented, including biotoxins in shellfish, chemical residues in salmon and the disease status of shellfish and finfish.

Electronic Resource

1440-1770

Blackwell Publishing Journal Backfiles 1879-2005

Geography

Considerable attention has been paid to the downstream effects of reservoirs on the ecology of rivers, streams and wetlands. However, most reservoirs were constructed well before ecological concerns became prominent. Little attention has been given to the question of what extent existing structures and management systems can accommodate changes. The paper discusses this matter and a range of associated issues. It is concluded that many problems can be rectified by structural means but that such rectification will be very expensive. While based primarily on Australian systems, the conclusions and examination are considered to be globally applicable.

Electronic Resource