Search Results - (Author, Cooperation:D. Patterson)

2018-02-28

Wiley-Blackwell

0270-9139

1527-3350

Medicine

2018-03-16

American Physical Society (APS)

1050-2947

1094-1622

Physics

Atomic and molecular structure and dynamics

2018-08-24

American Chemical Society (ACS)

1535-3893

1535-3907

Chemistry and Pharmacology

2018-03-22

American Chemical Society (ACS)

1535-3893

1535-3907

Chemistry and Pharmacology

2015-02-01

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2018-10-31

American Chemical Society (ACS)

1535-3893

1535-3907

Chemistry and Pharmacology

2016-05-05

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

2015-12-18

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Agriculture/*history ; Animals ; *Ecosystem ; History, Ancient ; Human Activities/*history ; Humans ; North America ; *Plant Physiological Phenomena ; Population Dynamics ; Time Factors

2013-05-24

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

2018-05-10

Institute of Physics Publishing (IOP)

1748-0221

Physics

2018-10-03

Institute of Physics Publishing (IOP)

1748-0221

Physics

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

An eight-channel beam-emission-spectroscopy (BES)1 system has been installed on the Alcator C-Mod tokamak, intended for use with a diagnostic neutral hydrogen beam (DNB). Capable of localized measurements from the plasma edge to the plasma core, the BES diagnostic collects light from the first Balmer transition (Hα) resultant from beam/plasma collisions. The Hα line splits into several components whose central wavelengths depend on the viewing geometry, the magnetic field, and the beam energy. This is due to the Doppler shifts from viewing the beam off perpendicular, the different velocities of the three mass components of the beam (H, H2, H3), and the large motional Stark effect. Optimal signal-to-noise requires collecting these components while attenuating all other emission: primarily bremsstrahlung and Dα radiation (from plasma D0/e− collisions). Tunable bandpass filters are thus required. A BES simulation code has been developed that calculates the brightnesses (bremsstrahlung, Dα, Hα) versus wavelength using plasma profile data from the C-Mod MDSplus database,2 a computation of the beam penetration, the viewing and DNB geometries, and bandpass filter characteristics. The model was first used to estimate signal levels and choose the optimal BES bandpass filters; its ultimate purpose is to determine the shot-to-shot tuning requirements of the filters for different discharge conditions. Comparisons of measured and predicted background bremsstrahlung and Dα brightnesses are presented, as are first measurements and calculations of the beam emission. The code is written in the IDL programming language3 utilizing the "widget" graphical user interface. Designed for geometrical and spectral flexibility, it can be modified to simulate other beam diagnostics such as motional-Stark-effect plasma current measurements and charge-exchange recombination spectroscopy, as well as passive diagnostics measuring chord-averaged spectral emission. © 2001 American Institute of Physics.

Electronic Resource

1365-2494

Blackwell Publishing Journal Backfiles 1879-2005

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

Eighty winter-calving dairy cows of mixed parity were managed in four grassland-based systems of milk production (F-F, F-C, C-F and C-C) over a full lactation (year 1) and during the winter period of the subsequent lactation (year 2). During the winter periods cows on systems F-F and F-C were offered silages of high feeding value, supplemented with 6·0 kg d−1 of concentrate [crude protein (CP), 307 g kg−1 dry matter (DM)] through an out-of-parlour feeding system, while cows on systems C-F and C-C were offered silages of medium feeding value, supplemented with c. 12·8 kg d−1 of concentrate (CP, 204 g kg−1 DM), in the form of a complete diet. After 25 February in year 1, cows on systems F-F and C-F were given access to grazing for periods of increasing duration, achieving full turnout on 17 April. Thereafter, until 21 October, these cows were offered a high daily allowance of herbage within a flexible grazing system (23·0 kg DM per cow, measured above a height of 4·0 cm), supplemented with 0·5 kg d−1 of a ‘high magnesium’ concentrate. Cows on systems F-C and C-C (year 1) commenced grazing on 1 April, achieving full turnout on 17 April. Thereafter, until 20 October, these cows were managed on a restricted allowance of herbage in a rotational paddock grazing system, with concentrates (average allocation, 3·9 kg d−1) being offered according to yield. In year 2, cows on systems F-F and C-F were given access to grazing for periods of increasing duration, from 11 March to 8 April, at which point the study was terminated.With systems F-F, F-C, C-F and C-C, mean feed inputs and milk outputs (per animal) during year 1 of the study were as follows: total concentrate DM intakes [881, 1272, 1729 and 2171 kg (s.e.m. 96·1)]; total silage DM intakes [1722, 1713, 1047 and 1154 kg (s.e.m. 70·7)], total grass DM intakes (3245, 2479, 3057 and 2481 kg) and total milk outputs [7541, 7527, 7459 and 7825 kg (s.e.m. 305·8)] respectively. Stocking rates associated with each of the four systems were 2·2, 2·5, 2·6 and 2·9 cows per hectare respectively. Performance of dairy cows on the systems during the winter of year 2 was similar to that recorded during year 1. The results of this study indicate that similar levels of milk output, DM intakes, tissue changes and plasma metabolite profiles can be achieved from grassland-based systems involving very different combinations of grass silage, grazed grass and concentrate feeds.

Electronic Resource

1365-2494

Blackwell Publishing Journal Backfiles 1879-2005

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

Abstract The effects of level of concentrate supplementation on the response of dairy cows to grass silage-based diets containing a constant proportion of fodder beet were examined. Forty Holstein-Friesian dairy cows of mixed parity were used in a 2 × 5 factorial design experiment. Two basal diet types [grass silage alone or grass silage mixed with fodder beet in a 70:30 dry matter (DM) ratio] were offered ad libitum, and the effects of five levels of concentrate supplementation (mean = 3·0, 5·3, 7·5, 9·8 and 12·0 kg DM per cow d−1) were examined. Concentrate supplements were offered via an out-of-parlour feeding system. These treatments were examined in a three-period (period length = 4 weeks) partially balanced changeover design experiment.Fodder beet inclusion had no significant effect on the estimated metabolizable energy (ME) concentration of the ration (P 〉 0·001). Total DM intake, estimated ME intake, milk yield, milk protein content and milk energy output all showed significant linear increases with increasing level of concentrate inclusion (P 〈 0·001) while, in addition, milk yield and milk energy output exhibited a significant quadratic increase (P 〈 0·01). The inclusion of fodder beet in the diet reduced silage DM intake (P 〈 0·01) but resulted in an increase in total DM intake and estimated ME intake (P 〈 0·001). However, inclusion of fodder beet had no significant effect on milk yield (P 〉 0·05), while increasing milk protein content and milk energy output (P ≤ 0·05). Milk energy output, as a proportion of estimated ME intake, was significantly (P 〈 0·001) reduced by fodder beet inclusion (0·44 vs. 0·38).Despite large increases in estimated ME intake with the inclusion of fodder beet at all levels of concentrate supplementation, milk energy output responses were small, resulting in an overall reduction in the efficiency of conversion of ME intake into milk energy output. An increased partitioning of dietary ME intake to tissue gain is suggested as the most likely explanation for the observations made.

Electronic Resource

1365-2494

Blackwell Publishing Journal Backfiles 1879-2005

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

The rates of drying of perennial ryegrass, subjected to different treatments at mowing and after mowing, were assessed in the field by weight change of grass fresh weight in wire-mesh trays over 3·5 d (76 h). In a 5 × 3 × 3 factorial experimental design, the effects of five weights of grass per unit area [1·5, 3, 6, 12 and 24 kg fresh material (FM) m−2], three treatments at mowing (no treatment, mower-conditioned, flail-treated) and three treatments after mowing (no treatment, inverted, mixed) were examined. The experiment was replicated twice on 16 occasions in 1992 at the Agricultural Research Institute of Northern Ireland. This gave a total of thirty-two replicates per treatment. The trays were weighed at 2-h intervals from 09.00 to 17.00 h each day. Data sets were restricted to rain-free days and also to the first day after mowing (day 1). On day 1, grass weight per unit area was a major factor dictating drying; reducing the grass weight per unit area of unconditioned grass from 6 to 3 kg FM m−2 increased grass drying rate by 47%. There was no significant (P 〉 0·05) benefit over the untreated grass on day 1 from mixing or turning mower-conditioned or the unconditioned grass. Mixing of the flail-treated grass improved drying rate significantly (P 〉 0·001) over the control. Over the whole 76-h period, the relative benefit from either mower conditioning or flail treatment over no treatment was dependent upon both grass weight per unit area and initial dry-matter (DM) concentration. At higher initial DM concentrations (〉150 g kg−1) and lower grass weights (〈6 kg FM m−2) both mower conditioning using a nylon brush type conditioner and intensive conditioning by flail treatment gave substantial increases in drying over no treatment. Moisture regain of grass exposed to overnight dew was small. Rain had a much greater effect than dew on subsequent moisture regain. Unconditioned grass at 12 kg m−2 retained 82% less water following rainfall than unconditioned grass at 3 kg m−2.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Abstract— The chemical composition of four parts of the CNS (cerebrum, cerebellum, brain stem and spinal cord) was determined in 107 pigs at 11 stages of fetal and postnatal development and also in 6 adults. In cerebrum, cerebellum and brain stem, but not in spinal cord, the rate of increase in weight and the rates of change in lipid content slowed down for a period of about 10 days before and after birth. Cholesterol esters and desmosterol were only found in progressively decreasing amounts during the fetal stages of development and together with DNA these were exceptions to the general increases in the tissue concentrations and total amounts of other components during the period studied.The onset of myelination, as measured by calculated daily increases in tissue contents of cerebroside took place between 70 and 80 days conceptual age and there were two peaks of activity, the first occurring 2 weeks before and the second 3 weeks after birth. Unlike the rate curve for total spinal cord weight the biphasic accumulation of DNA was not synchronous with myelin lipid accretion and the earlier prenatal DNA peak probably denotes proliferation of oligodendrocytes. The two phases of myelination are discussed in relation to an observed generalized pause in development immediately before and after birth.Fatty acid analysis of cerebrosides indicated that, in spinal cord, chain elongation and desaturation are associated with myelination and continue with increasing activity until maturity. Consequently there was a progressive decrease in the proportion of saturated fatty acids. The fatty acid components of cholesterol esters in the developing pig were shown to be similar to those found during development in the CNS of other species but different from those found in demyelinating conditions.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Abstract— In piglets affected with congenital tremor type AII the CNS was not morphologically underdeveloped; spinal cord weight, total DNA content and fat-free dry matter differed little from control values. However the total lipid extractable from affected spinal cords was only about 63% of values established for normal newborn piglets. In particular, the cerebroside content (a myelin-specific lipid) was reduced to about 30% of the ‘normal’ value. This was parallelled by the results of an in vitro assay of cerebroside synthesis from [3H]galactose which indicated a metabolic impairment. The altered fatty acid profile of isolatcd cerebrosides further suggested a derangement of fatty acid synthesis. Unlike the spinal cords of normal newborn piglets, tissues from affected piglets contained significant amounts of cholesterol esters carrying the characteristic fatty acids associated with demyelination. This implied that the reduced quantities of possibly abnormal myelin were unstable. Abnormal swollen oligodendrocytes were commonly present in the spinal cords of affected piglets and this was consistcnt with the observed impairment of myelin formation.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Congenital tremor, type A-IV is an inherited abnormality of British Saddleback piglets characterized by the presence of poorly myelinated axons throughout the CNS. This is reflected by a general lowering of the spinal cord lipid content to about half control values. In particular, cerebroside and plasmalogen levels are markedly reduced.Changes in the fatty acid composition of total lipid extracts and two isolated cerebroside fractions suggest that there is a metabolic defect in which fatty acid chain elongation, desaturation and hydroxylation are sub-optimal.Cholesterol esters accumulate, make up about 30 per cent of total sterols and contain more than 90 per cent of C16 and C18 fatty acids. These may have arisen through the breakdown of cerebrosides containing abnormal proportions of these acids. Slightly increased levels of acid hydrolase activity appear to confirm that abnormal or immature myelin is disposed of by enhanced macrophagic activity.Differences between this and type A-III, the sex-linked inherited form of cerebrospinal hypomyelinogenesis are discussed and comparisons made with two forms of murine leuko-dystrophy.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

(1) The chemical composition of the CNS (separated into cerebrum, cerebellum, brain stem and spinal cord) was determined in sheep during foetal and post-natal development and in adults.(2) The spinal cord differed from the remainder of the CNS in growing more after the period studied (50-day-old foetuses to 5-week-old lambs) than before it. This was largely attributable to lipid accumulation.(3) Chemical growth (accumulation of DNA, protein and lipid) proceeded linearly in spinal cord, logarithmically in cerebrum and cerebellum while in brain stem growth was described by a sigmoid function.(4) Fat-free dry matter, protein, total lipid, cholesterol and phospholipid concentrations increased progressively in all parts of the CNS but DNA concentrations changed little. In the cerebrum alone there was an increase in DNA concentration during maturation suggesting an increased cell population. Cholesterol was present predominantly in the free form but esters were detected in foetal tissues from 70 up to 120 days gestation.(5) Cerebroside, the characteristic lipid of myelin, increased in concentration soon after 85 days of gestation, up to which point very low values were recorded, the rate varying according to the region of the CNS examined. Rates of increase in total regional cerebroside content were used to identify periods of myelination and the results suggest that there are two periods of peak activity, one about 20 days before birth and the other at 10-20 days after birth.(6) The composition of lipids added during the two phases of myelination and during maturation were characteristically different. In the spinal cord, lipid analyses best reflect changes in myelin composition.

Electronic Resource