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

2018-04-04

National Academy of Sciences

0027-8424

1091-6490

Biology

Medicine

Natural Sciences in General

2011-04-16

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Africa ; Cultural Evolution ; Founder Effect ; Geography ; Humans ; *Language ; Models, Theoretical ; *Phonetics ; Population Density

2016-04-05

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Bayes Theorem ; *Ceremonial Behavior ; *Cultural Evolution ; Humans ; Models, Theoretical ; Oceanic Ancestry Group/psychology ; Phylogeny ; Religion and Psychology ; *Social Class ; *Social Control, Formal

2011-11-11

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Bayes Theorem ; *Biological Evolution ; Female ; Group Processes ; Male ; Markov Chains ; Models, Biological ; Monte Carlo Method ; Phylogeny ; Predatory Behavior ; Primates/anatomy & histology/*physiology ; Sex Factors ; *Social Behavior

2016-02-11

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Altruism ; *Cooperative Behavior ; Ethnic Groups/psychology ; Female ; Games, Experimental ; Humans ; Internationality ; *Interpersonal Relations ; Interviews as Topic ; Logistic Models ; Male ; *Morals ; Odds Ratio ; Punishment/*psychology ; Random Allocation ; *Religion and Psychology ; Trust

2018-09-26

National Academy of Sciences

0027-8424

1091-6490

Biology

Medicine

Natural Sciences in General

2013-08-13

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Blood Platelets/*cytology ; *Cell Differentiation ; Cell Lineage/genetics ; Female ; Gene Expression Regulation, Developmental ; Hematopoietic Stem Cell Transplantation ; Hematopoietic Stem Cells/*cytology/metabolism ; Lymphocytes/cytology ; Male ; Mice ; Mice, Inbred C57BL

2012-08-28

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Agriculture/history ; Bayes Theorem ; *Cultural Evolution ; History, Ancient ; Humans ; Language/*history ; Linguistics/history ; Phylogeography ; Turkey ; Vocabulary

2013-06-14

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

2018-04-13

American Society of Hematology (ASH)

0006-4971

1528-0020

Biology

Medicine

Hematopoiesis and Stem Cells

2018-09-05

The Society of Nuclear Medicine (SNM)

0022-3123

Medicine

1089-7550

AIP Digital Archive

Physics

The effect of furnace annealing on the magnetic and magnetoelastic properties of amorphous wire of composition Fe77.5Si7.5B15 has been investigated. The field dependence of Young's modulus and magnetization combined with x-ray analysis and scanning electron microscopy have been used to monitor the effects of annealing. The results indicate that progressive annealing leads first to relief of the radial casting stress with a corresponding reduction in angle between the average easy direction and the wire axis. Further annealing leads to surface crystallization for which it is suggested that the moments take up a circumferential orientation. Annealing still further leads to crystallization of the bulk material which greatly increases the anisotropy and greatly reduces the ΔE effect.

Electronic Resource

1089-7658

AIP Digital Archive

Mathematics

Physics

The quark propagator in massless quantum chromodynamics (QCD) is analyzed using the gauge technique. In both the Feynman and Landau gauges with a Pauli–Villars cutoff, a chirally symmetric solution is found, while a nonsymmetric solution appears at a critical coupling λc〉0. As the cutoff is removed, λc tends to 0 but the nonsymmetric solution vanishes in the continuum limit, so that chiral symmetry is then restored.

Electronic Resource

1089-7658

AIP Digital Archive

Mathematics

Physics

An improved ansatz for the three-gluon vertex function is treated; and it is shown that the gluon propagator has a double pole at the origin of the p2 plane, as well as a tachyon on the spacelike real axis, at least in this approximation.

Electronic Resource

1475-2743

Blackwell Publishing Journal Backfiles 1879-2005

Geosciences

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

Abstract. Effects on soil physical properties in a trial which compared establishing an apple orchard on grassed and cultivated soil and of maintaining soil with or without a vegetative cover post-planting are discussed. On a fine sandy loam soil (Fyfield series) prone to erosion, bulk density, water filled porosity and soil erosion, measured at intervals after the establishment year, were all unaffected by the use of grass. Infiltration rate was much higher on grassed than on herbicide treated soil as was the apparent ability to accept heavy rainfall.

Electronic Resource

1475-2743

Blackwell Publishing Journal Backfiles 1879-2005

Geosciences

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

Abstract. Complex relationships exist between different components of the organic farm and the quantity and quality of the end products depend on the functioning of the whole system. As such, it is very difficult to isolate soil fertility from production and environmental aspects of the system. Crop rotation is the central tool that integrates the maintenance and development of soil fertility with different aspects of crop and livestock production in organic systems. Nutrient supply to crops depends on the use of legumes to add nitrogen to the system and limited inputs of supplementary nutrients, added in acceptable forms. Manures and crop residues are carefully managed to recycle nutrients around the farm. Management of soil organic matter, primarily through the use of short-term leys, helps ensure good soil structure and biological activity, important for nutrient supply, health and productivity of both crops and livestock. Carefully planned diverse rotations help reduce the incidence of pests and diseases and allow for cultural methods of weed control. As a result of the complex interactions between different system components, fertility management in organic farming relies on a long-term integrated approach rather than the more short-term very targeted solutions common in conventional agriculture.

Electronic Resource

1475-2743

Blackwell Publishing Journal Backfiles 1879-2005

Geosciences

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

Abstract. The mean extractable sulphur (S) concentration in 315 upland topsoil samples collected in 1988/89 from beneath pasture in NE Scotland was 13 μg S g−1 (range 2–77 μg S g−1). More than two thirds of the samples had S concentrations less than that acceptable for productive soils. Continued decreases in atmospheric S inputs may have increased this proportion subsequently. The analysis of herbage S also indicated that two-thirds of the samples were below 0.2% S. A ‘respirometric index’, namely CO2 produced during cellulose decomposition without added S as a percentage of that produced with added S, was significantly less than 100% in a quarter of the soils. Results of three different extraction procedures suggested that sulphate in the soils was present mainly as free plus adsorbed rather than precipitated forms. Soil extraction identified a significant non-sulphate S fraction, presumably organic S. The variability in extractable S stemmed from a combination of geographical, depositional and local site and soil factors. Extractable S was significantly correlated with soil organic matter content and inversely with soil pH and together these factors explained 37% of the variability. While significant differences in mean concentrations between geographical area, soil association and drainage status were evident, no trends could be observed between the major soil subgroups or with altitude.

Electronic Resource

1365-2389

Blackwell Publishing Journal Backfiles 1879-2005

Geosciences

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

The production of fine roots is one of the principal means by which carbon, fixed during photosynthesis, enters the soil, and quantifying the production for particular combinations of environmental and biotic factors is important for predicting the sequestration of carbon in the soils of grassland ecosystems. Arbuscular mycorrhizal fungi (AMF) can have a major effect on the production of roots, and we studied how colonization by AMF affects the lifespan of roots. Twenty per cent of control roots of Trifolium repens survived for longer than 42 days whereas 37% survived that long in AMF-colonized plants. The overall survival of the roots of Lolium perenne was less than in T. repens: around 10% of roots survived beyond 42 days and this was not affected by AMF colonization. Previous studies have shown that lifespans of roots can be affected by temperature. We tested the hypothesis that these observations are linked to a change in the morphology of the root system caused by temperature and also by AMF. We found that inoculation with AMF in a microcosm study using Plantago lanceolata grown at various temperatures, with and without AMF, showed no clear effect of AMF on branching patterns. Temperature had a significant effect on total lengths, numbers and branching rates of some higher orders of roots. Total lengths of both secondary and tertiary roots grown at 27°C were about double those of plants grown at 15°C. Colonization by AMF tended to reduce this effect. Evidently the effect of colonization by AMF on root lifespan depends on the species. Increased branching, and thus a greater proportion of ephemeral roots, was responsible for shortening the lives of the roots at increased temperature, which suggests a strong link between lifespan and morphology.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The field dependence of Young's modulus (ΔE effect) of amorphous wires of Co72.5Si12.5B15 has been studied in the as-quenched state, and after annealing for times between one and several hundred minutes at temperatures of 450, 480, and 500 °C. In the as-quenched state the ΔE effect is small (〈2%), because the quenching stresses couple with the magnetostriction (λs∼−3×10−6) to produce significant anisotropy. Annealing for short times ((approximately-greater-than)1 min) is sufficient to relieve much of the quenching stress, resulting in magnetic softening and enhanced ΔE effect (at best (approximately-greater-than)30%). Further annealing eventually reverses these trends, increasing coercivity and anisotropy, and reducing the ΔE effect. This behavior is attributed to surface crystallization. The results are interpreted in terms of the core-shell domain model, and are consistent with the retention of a significant component of circumferential domain structure in the shell in all annealing conditions studied. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The dependence of magnetoimpedance (MI) on transverse susceptibility in soft ferromagnets is used in conjunction with an existing phenomenological domain structure model to study the relative importance of moment rotation and domain-wall motion in MI. It is shown that moment rotation is predominantly responsible for the observed behavior in amorphous wires at frequencies above 1 MHz. It is also necessary to include anisotropy distributions in both magnitude and direction. © 1998 American Institute of Physics.

Electronic Resource