Search Results - (Author, Cooperation:G. Gibson)

2014-02-28

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Cohort Studies ; Epistasis, Genetic/*genetics ; Europe/ethnology ; Female ; Gene Expression Profiling ; Gene Expression Regulation/*genetics ; Genetic Association Studies ; Humans ; Linkage Disequilibrium ; Male ; Pedigree ; Polymorphism, Single Nucleotide/genetics ; Quantitative Trait Loci ; Reproducibility of Results ; Transcription, Genetic/*genetics

2011-07-02

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2014-08-01

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Colorectal Neoplasms/*genetics ; Gene Expression Regulation, Neoplastic/*genetics ; Humans ; Regulatory Sequences, Nucleic Acid/*genetics

2016-03-26

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Artificial Cells ; Codon/genetics ; DNA Transposable Elements ; DNA, Bacterial/*chemical synthesis/genetics ; Genes, Essential ; Genes, Synthetic/genetics/*physiology ; *Genome, Bacterial ; Mutagenesis ; Mycoplasma mycoides/*genetics ; Proteins/genetics ; RNA/genetics ; Synthetic Biology

2015-05-09

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Disease/*genetics ; Female ; *Gene Expression Regulation ; *Genetic Variation ; Genome, Human/*genetics ; Humans ; Male ; Proteins/*genetics ; *Quantitative Trait Loci ; *Transcriptome

2014-05-09

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

*Chromosomes, Fungal ; Saccharomyces cerevisiae/*genetics ; Synthetic Biology/*methods

2012-06-08

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Aging ; Animals ; Bacteria/*metabolism ; Diet ; Gastrointestinal Tract/*metabolism/*microbiology ; Health ; Humans ; Immune System/physiology ; Inflammation ; Liver/metabolism ; Metabolic Diseases/metabolism/*microbiology ; *Metabolic Networks and Pathways ; *Metagenome ; Signal Transduction

2014-10-04

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Epistasis, Genetic/*genetics ; Female ; Gene Expression Regulation/*genetics ; Humans ; Male ; Transcription, Genetic/*genetics

1089-7550

AIP Digital Archive

Physics

A high-resolution, high-sensitivity magnetic force microscope (MFM) with the ability to image in an in situ magnetic field is described. This MFM has been used to investigate the micromagnetics of nanolithographically produced magnetic particles. It is shown that the particles' switching fields can be determined without being perturbed by the stray fields from the sensing tip. This allows the study of the evolution of the particles' magnetic states as a function of applied field and the direct observation of cooperative switching among interacting particles. The switching fields of individual particles are compared with remanent magnetization data, taken with an alternating gradient magnetometer, on both isolated and interactive arrays of particles. A method is described for estimating the strength of the interaction between particles by comparing the switching fields of different configurations of particle moments created by using the MFM tip as a local field source. Finally, a novel remanent magnetization state has been observed which provides a check on the validity of micromagnetic numerical simulations.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

An extremely sensitive alternating gradient magnetometer (AGM) has been developed. This AGM has been designed as an aid in characterizing the response of magnetic force microscope tips to known magnetic fields and field gradients. It should also prove useful as a general purpose magnetometer for small samples. A sensitivity of ∼ 1.4 × 10−11 emu has been achieved. Minor improvements in vibration isolation should bring this number down to ∼ 10−12 emu. A sensitivity of ∼ 10−14 emu is theoretically possible. The capabilities of the AGM are illustrated with magnetization versus field data for an 8-μm Ni sphere.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Magnetic force microscopy (MFM) has been widely utilized to reveal magnetization distributions by sensing the external magnetic-field distribution very close to the sample. The resolution of MFM is determined by the size of the sensor tip and by the spacing between the tip and the measured sample. A technique is developed to analyze the noise and linearity of a MFM image, and consequently to improve the spatial resolution by reducing the spacing loss. As a demonstration, a series of MFM images of a single permalloy particle is obtained and numerically analyzed. The spacing loss is reduced and a much higher resolution image is obtained.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

A magnetic force microscope (MFM) has been shown to be able to detect fields emanating from submicrometer permalloy particles with magnetic moments as low as 10−13 emu. We have used this MFM equiped with an in situ electromagnet to study the angular dependence of the switching field Hs(θ), and the probability of thermal switching of a single-domain permalloy particle as a function of the time duration of an applied magnetic field H. The angular dependence of Hs(θ) is significantly different from that expected for coherent rotation. For applied magnetic fields close to Hs, the time dependence of the probability for not switching cannot be fit with a simple exponential. These data indicate that multiple-energy barriers of similar height are involved in the thermally activated process responsible for the reversal.

Electronic Resource

1525-1314

Blackwell Publishing Journal Backfiles 1879-2005

Geosciences

Ion microprobe dating of zircon and monazite from high-grade gneisses has been used to (1) determine the timing of metamorphism in the Western Province of New Zealand, and (2) constrain the age of the protoliths from which the metamorphic rocks were derived. The Western Province comprises Westland, where mainly upper crustal rocks are exposed, and Fiordland, where middle to lower crustal levels crop out. In Westland, the oldest recognisable metamorphic event occurred at 360–370 Ma, penecontemporaneously with intrusion of the mid-Palaeozoic Karamea Batholith (c. 375 Ma). Metamorphism took place under low-pressure/high-temperature conditions, resulting in upper-amphibolite sillimanite-grade metamorphism of Lower Palaeozoic pelites (Greenland Group). Orthogneisses of younger (Cretaceous) age formed during emplacement of the Rahu Suite granite intrusives (c. 110 Ma) and were derived from protoliths including Cretaceous Separation Point suite and Devonian Karamea suite granites. In Fiordland, high-grade paragneisses with Greenland Group zircon age patterns were metamorphosed (M1) to sillimanite grade at 360 Ma. Concomitant with crustal thickening and further granite emplacement, M1 mineral assemblages were overprinted by higher-pressure kyanite-grade metamorphism (M2) at 330 Ma. It remains unclear whether the M2 event in Fiordland was primarily due to tectonic burial, as suggested by regional recumbent isoclinal folding, or whether it was due to magmatic loading, in keeping with the significant volumes of granite magma intruded at higher structural levels in the formerly contiguous Westland region. Metamorphism in Fiordland accompanied and outlasted emplacement of the Western Fiordland Orthogneiss (WFO) at 110–125 Ma. The WFO equilibrated under granulite facies conditions, whereas cover rocks underwent more limited recrystallization except for high-strain shear zones where conditions of lower to middle amphibolite facies were met. The juxtaposition of Palaeozoic kyanite-grade rocks against Cretaceous WFO granulites resulted from late Mesozoic extensional deformation and development of metamorphic core complexes in the Western Province.

Electronic Resource

1478-1913

Blackwell Publishing Journal Backfiles 1879-2005

Theology and Religious Studies

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Abstract: An alteration in signal transduction systems in Alzheimer's disease (AD) would likely be of pathophysiological significance, because these processes control normal brain functions. Previously, a diminished β-adrenergic-mediated cyclic AMP response was found in cultured fibroblasts from AD patients. Because cross-talk between the phosphoinositide and cyclic AMP pathways exists, the phosphoinositide cascade was studied under conditions that were similar to those for studying the cyclic AMP response. Cells from AD patients and age-matched controls responded to bradykinin (BK) and released inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in a time- and dose-dependent manner. The level of Ins(1,4,5)P3 increased rapidly and transiently in response to BK, peaked at 5 s, but still remained 116–132% above the basal level by 30 s. Although the temporal patterns were similar in both groups, the Ins(1,4,5)P3 concentrations in AD fibroblasts were 73 and 89% above levels in the age-matched controls at 5 and 10 s, respectively. Prostaglandin E1 also increased Ins(1,4,5)P3 formation, but this response was not different between the two groups. Although KD (affinity) values for the BK receptor were similar in both control and AD cells, the number of BK receptors (Bmax) was significantly elevated in AD fibroblasts (186.8 ± 0.8 fmol/mg of protein) as compared with control fibroblasts (57.2 ± 15.3 fmol/mg of protein). These results indicate that the elevated Ins(1,4,5)P3 production in response to BK in AD fibroblasts is positively correlated with an increase in the receptor numbers.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Insulin-induced hypoglycemia in normothermic rats caused progressive neurological depression and differentially altered regional cerebral acetylcholine metabolism. Reductions of plasma glucose from 7.7 mM (control) to 2.5-1.7 mM (moderate hypoglycemia associated with decreased motor activity) or 1.5 mM (severe hypoglycemia with lethargy progressing to stupor) decreased glucose concentrations in the cerebral cortex, striatum, and hippocampus to 〈 10% of control. Moderate hypoglycemia diminished acetylcholine concentrations in cortex and striatum (21% and 45%, respectively) and reduced [1-2H2, 2-2H2]choline incorporation into acetylcholine (62% and 41%, respectively). Severe hypoglycemia did not reduce the acetylcholine concentration or synthesis in cortex and striatum further. The concentrations of choline rose in the cortex (+ 53%) and striatum (+ 130%) of animals that became stuporous but a similar rise in [1-2H2, 2-2H2]choline left the specific activities of choline in these structures unchanged. Even severe hypoglycemia did not alter the hippocampal cholinergic system. In rats that developed hypoglycemic stupor and were then treated with glucose, the animals recovered apparently normal behavior, and the concentrations of acetylcholine and the incorporation of [1-2H2, 2-2H2]-choline into acetylcholine returned to control values in the striatum but not in the cerebral cortex. Thus, impaired acetylcholine metabolism in selected regions of the brain may contribute to the early symptoms of neurological dysfunction in hypoglycemia.

Electronic Resource

1365-2494

Blackwell Publishing Journal Backfiles 1879-2005

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

Aerobically spoiled silage has often been shown to harbour dangerously high levels of Listeria monocytogenes. This paper investigates the dynamics of aerobic deterioration in a silage bale as it occurs close to a site of damage to the cover. The underlying aim was to enable prediction of the extent of the silage that may become suitable for Listeria growth during the course of storage. In order to meet these objectives, a model was formulated that represents the microbiology of the deterioration process and the transport of oxygen and heat through the silage. The geometry of the system was exploited to ensure that the model is computationally tractable. The model was used to evaluate the effect of silage pH and puncture size on the risk of Listeria contamination. Although the hazardous fraction was seen to be relatively insensitive to the initial pH of the silage, it increased rapidly with puncture size. However, a small puncture can result in the ‘loss’ of a considerable fraction of the bale because of the relatively long time scale over which bales are stored.

Electronic Resource

1365-2494

Blackwell Publishing Journal Backfiles 1879-2005

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

A mathematical model of the aerobic stability of grass silage is presented. The model is shown to predict as well as more complex models previously published. Sensitivity analysis performed on model parameters suggests that current understanding of the temperature dependence of yeast growth needs to be advanced in order to produce more accurate models of deterioration. Inhibition of yeast growth by organic acids is identified as a critical process worthy of further investigation. We discuss how model validation experiments must identify different yeast species and track their growth separately. Such experiments should also attempt to minimize or measure heat losses.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The properties of tunnel barriers made with amorphous Ge (a-Ge) deposited at approximately 80 K were studied in Al/a-Ge/Al tunnel junctions and also in junctions where one electrode was Ni or Fe. The conduction process was shown to be tunneling for barriers less than about 100 A at liquid He temperature and consistent with Mott variable-range hopping for higher temperatures and thicknesses. Measurements were made of current density J and dynamic conductance dJ/dV as a function of voltage V, thickness s, and temperature T. The measurements were compared with available theoretical expressions for rectangular tunnel barriers based on the WKB approximation. The applicability of these expressions for barrier heights less than 100 meV was examined and a modified equation for J(V) was derived which eliminated assumptions which are inaccurate for such low barriers. The measurements were also compared to this modified equation and to numerical solutions. Values for the effective tunnel barrier height ranging from 20 to 80 meV were obtained. Theoretical expressions for J(V) could be fitted to the measurements fairly well, but not perfectly; for J(T) the fit was poor. Values of s obtained using the modified expression for J(V) tended to be 10%–20% less than those measured by a quartz-crystal thickness gauge using the bulk crystal density. The conductance peaks corresponding to the peaks in the superconducting density of states were considerably broadened over Al/Al2O3/Al junctions either because of depairing of the Al films in contact with a-Ge or from an inelastic process in the barrier. No spin polarization of the tunnel currents was observed when one of the electrodes was Ni or Fe. Some measurements were made of a-Ge barriers treated with glow discharges in N2, O2, and H2. The properties of a-Ge were very similar to those previously found for a-Si. Evidently the basic conduction process in these junctions is tunneling, but the simple tunneling model cannot entirely explain the results. Various proposals to account for these divergences from the simple tunneling model are discussed.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Abstract— Lowering the concentration of oxygen or of glucose to which mouse and rat brains were exposed impaired the synthesis of acetylcholine from labelled precursors in vivo.Histotoxic hypoxia induced with KCN or anemic hypoxia induced with NaNO2 (to oxidize hemoglobin to methemoglobin) reduced incorporation of [2H4]choline into acetylcholine. This change in acetylcholine metabolism occurred with doses of KCN or NaNO2 which did not alter the concentrations of ATP or ADP or the adenylate energy charge. Hypoglycemia induced by large doses of insulin also reduced the incorporation of [2H4]choline into acetylcholine. Both hypoxia and hypoglycemia increased the concentration of choline in the brain. The specific activity of choline did not decrease in hypoxia; it did not decrease enough in hypoglycemia to explain the reduced incorporation of [2H4]choline into acetylcholine.Pretreatment with the cholinesterase inhibitor physostigmine delayed the onset of both seizures and death in mice after induction of hypoxia by large doses of NaNO2. Pretreatment with physostigmine also decreased the number of mice dying within 3 h after the induction of hypoglycemia with large doses of insulin. These observations suggest that the effects of hypoxia and hypoglycemia interfere with the synthesis of a critical pool of acetylcholine.The incorporation of labelled precursors into acetylcholine related linearly to both the cytoplasmic redox state (NAD/NADH ratio) and to the NAD/NADH potential across the mitochondrial membrane. The redox potential of NAD/NADH in the cytoplasm was calculated from the [pyruvate]/[lactate] equilibrium and the redox potential of NAD/NADH in the mitochondria from the [NH4][2-oxoglutar-ate]/[glutamate] equilibrium. The potential across the mitochondrial membrane was calculated from the difference.These observations indicate that carbohydrate oxidation is one of the factors on which the synthesis of the neurotransmitter acetylcholine depends closely in mouse and rat brain.

Electronic Resource