Search Results - (Author, Cooperation:J. A. Harris)

2014-04-04

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Atlases as Topic ; Axons/physiology ; Brain/*anatomy & histology/*cytology ; Cerebral Cortex/cytology ; *Connectome ; Corpus Striatum/cytology ; Male ; Mice ; Mice, Inbred C57BL ; Models, Neurological ; Neuroanatomical Tract-Tracing Techniques ; Thalamus/cytology

2018-07-03

Rockefeller University Press

0022-1007

1540-9538

Medicine

Neuroinflammation, Neuroscience

1526-100X

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Electronic Resource

1526-100X

Blackwell Publishing Journal Backfiles 1879-2005

Biology

The microbial community in a soil stripped and stored during opencast coal mining was analyzed. There were significant effects of soil disturbance on the microbial community: in particular, there were large decreases in the total microbial biomass, as determined by ATP analysis, and numbers of fungal propagules as a result of the store construction process, but there was no significant effect on the numbers of bacteria. During the subsequent months of storage there was a flush in the numbers of bacteria, with gram-negative bacteria showing an increase of nearly 700% in comparison to the control. During this time there was a steady accumulation in the amount of ammonium in the deepest part of the soil store, indicating the onset of anaerobiosis. These changes may be interpreted in terms of lifestyle strategy theory (Grime 1979). The bacteria exhibit behavior typical of R-strategists, or ruderal species, taking advantage of the nutrients made available by the death of fungal biomass during store construction. Fungi respond as C-strategists, or competitors, and they are severely affected by store construction-and unable to persist deep in the anaerobic part of the store. In contrast, anaerobes, S-strategists or stresstolerators, are able to survive under the same conditions. These changes have serious implications for the restoration of systems using stored topsoil as a resource. The microbial population has been altered in terms of its size and composition. Many of the fungi required for adequate breakdown and incorporation of organic matter will be absent, and the soils will be generally poor in microbial biomass. This will lead to inadequate nutrient cycling and poor soil structural stability, two factors essential for the restoration of a self-sustaining ecosystem.

Electronic Resource

1526-100X

Blackwell Publishing Journal Backfiles 1879-2005

Biology

The extent of human-induced change and damage to Earth's ecosystems renders ecosystem repair an essential part of our future survival strategy, and this demands that restoration ecology provide effective conceptual and practical tools for this task. We argue that restoration ecology has to be an integral component of land management in today's world, and to be broadly applicable, has to have a clearly articulated conceptual basis. This needs to recognize that most ecosystems are dynamic and hence restoration goals cannot be based on static attributes. Setting clear and achievable goals is essential, and these should focus on the desired characteristics for the system in the future, rather than in relation to what these were in the past. Goal setting requires that there is a clear understanding of the restoration options available (and the relative costs of different options). The concept of restoration thresholds suggests that options are determined by the current state of the system in relation to biotic and abiotic thresholds. A further important task is the development of effective and easily measured success criteria. Many parameters could be considered for inclusion in restoration success criteria, but these are often ambiguous or hard to measure. Success criteria need to relate clearly back to specific restoration goals. If restoration ecology is to be successfully practiced as part of humanity's response to continued ecosystem change and degradation, restoration ecologists need to rise to the challenges of meshing science, practice and policy. Restoration ecology is likely to be one of the most important fields of the coming century.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

A numerical model of fully developed turbulent channel flow over a moving wavy boundary is presented. The model is of the linear-stability type, employs a transformed coordinate system, and uses the finite difference method for solution. Both the time-independent mean flow and the time-dependent perturbation to the mean flow caused by the traveling wavy boundary are computed. A low-turbulence-Reynolds-number form of the k-epsilon turbulence closure model is employed and three levels of sophistication in modeling the wave-induced Reynolds stresses (in the transformed coordinate system) are introduced. These models are the viscous quasilaminar (VQL) model, the mean eddy viscosity (EV) model, and the full perturbation (FP) model. The model is applied to simulate previous experimental investigations of the flow over wavy boundaries (including a water wave) under a variety of conditions. The solutions generated using both the EV and FP Reynolds stress closure models generally demonstrate very good agreement with the available pressure, stress, velocity, and Reynolds stress experimental data. In contrast, due to its neglect of the perturbation Reynolds stresses, the simple VQL closure model has limited predictive ability, especially for downstream running waves whose wave speed exceeds about half the channel centerline velocity and for cases with low inverse Reynolds numbers (based on the shear velocity and wavelength). For the water wave case, the component of the wave growth rate due to the pressure mechanism predicted by the EV and FP models can be up to three times those of the VQL model in the gravity wave growth range.

Electronic Resource

1365-2389

Blackwell Publishing Journal Backfiles 1879-2005

Geosciences

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

Land degradation is of concern in many countries. In order for timely and effective interventions to be made to reverse this degradation it is necessary to have objective measurements of ecosystem status. By measuring characteristics of the soil microbial community we can assess the status of the microbial ecosystem and in that sense the quality of the soil, and the potential for, and progress of, restoration after degradation.Recent research has shown quantitatively how by measuring the soil microbial community we can assess degradation and the effects of management designed to reverse it. The size, composition and activity of the soil microbial community convincingly distinguish between systems, and between the impact of management strategies upon them. Measurements of these characteristics of the microbial community provide invaluable information for restoring degraded land and are ready for routine use. Specifically, profiles of phospholipid fatty acid contents, and substrate induced respiratory responses to different carbon substrates, will yield significant data upon which management decisions may be based.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] AN important result of the development of Moseley's **o atomic number rule has been the impetus it has given to the search for missing elements. It is true that later arrangements of the Periodic Table indicated that eka-csesium, eka- and dwi-manganese, and eka-iodine were missing, but there were ...

Electronic Resource

1570-7458

Haematobia irritans ; Musca autumnalis ; Hydrotaea irritans ; Muscidae ; cattle ; control ; flucythrinate ; ear-tags

Springer Online Journal Archives 1860-2000

Biology

Résumé Des boucles, contenant du flucythrinate, ont protégé totalement des génisses pour la production de lait contre Haematobia irritans L. lors de deux traitements expérimentaux dans le sud de l'Angleterre. Les effectifs de Musca autumnalis De Geer sur la face des génisses ont été réduits de 41% en utilisant un boucles et de 76% en utilisant deux. Un seul boucles réduit les effectifs d'Hydrotaea irritans Fallén de 90% sur le corps et de plus de 55% sur les pis. Les effectifs d'autres mouches nuisibles de moindre intérêt ont été réduits eux aussi. L'efficacité a été maintenue pendant les 14 semaines du traitement ce qui déborde efficacement le période de vol des 3 principales espèces de mouches nuisibles. Les battements d'oreille des génisses sont destinés à chasser M. autumnalis du visage, et les coups de queue à chasser H. irritans du ventre. Ce sont les deux principales espèces de mouches nuisibles connues comme vecteurs de bactéries pathogènes. Un programme est proposé pour optimaliser l'efficacité des boucles, tout en limitant les risques de résistance aux insecticides.

Abstract In two trials using diary heifers, in the south of England, ear-tags, containing flucythrinate, completely controlled Haematobia irritans (L). Musca autumnalis De Geer on the face were reduced by 41% using one tag and by 76% using two tags per heifer. A single ear-tag reduced numbers of Hydrotaea irritans (Fallén) on the body by 90% and on the teats by more than 55%. Other minor pestering flies were similarly controlled. Control was sustained over the entire 14 weeks duration of the trials which effectively encompassed the fly season of the three main pests. Ear-flicks by the heifers were related to dislodging M. autumnalis from the face, and tail flicks to dislodging Hy. irritans from the belly. These are the two commonest species of nuisance flies and are known to carry pathogenic bacteria. A management plan intended to maximise effective use of insecticidal ear-tags while minimising risks of insecticide resistance is described.

Electronic Resource

0022-3980

Psychology

1432-2072

Key words FG 7142 ; β-Carboline ; Benzodiazepine inverse agonist ; Latent inhibition ; Rat

Springer Online Journal Archives 1860-2000

Medicine

Abstract Six experiments used rats to study the effects of the β-carboline FG 7142 on extinction of fear responses (freezing) to an auditory cue that had signalled footshock. Subcutaneous injection of FG 7142 interfered with the development of extinction without having any detectable effect on the rats’ levels of fear prior to extinction. Injection of FG 7142 also reversed extinction, partially reinstating fear responses that had been extinguished previously. A similar reinstatement of extinguished fear was seen when rats were tested for fear of the cue in a different chamber. The reinstatement produced by FG 7142 and that caused by context shift were not additive: FG 7142 did not increase extinguished fear if rats were tested in the different chamber. Finally, FG 7142 had no detectable effect on the latent inhibition of fear produced by repeatedly presenting the cue alone before conditioning with shock, even though this inhibition, like extinction, was affected by a shift in context. The present findings indicate that GABA transmission at GABAA receptors is involved in the inhibition of extinguished fear, and that this effect of GABA is regulated by those cues that constitute the extinction context.

Electronic Resource

1432-2072

Formalin test ; Hypoalgesia ; Fear ; Novelty ; Conditioning ; Midazolam ; Naloxone

Springer Online Journal Archives 1860-2000

Medicine

Abstract Rats tested for sensitivity/reactivity to formalin-induced pain in either an aversively conditioned or a novel environment displayed immediate but transient hypoalgesic responses that were insensitive to either a benzodiazepine (midazolam) or an opioid antagonist (naloxone). Exposure to the aversively conditioned, but not to the novel environment also provoked a more enduring hypoalgesic response that was abolished by either midazolam or naloxone. The results were taken to mean that fear is sufficient but not necessary for the production of hypoalgesic responses to environmental stimuli.

Electronic Resource

1432-1424

Membrane dynamics ; Osmotic perturbations ; Mechanical stress ; Cell adhesion ; Cytomechanics ; Rhodamine dextran

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Abstract In cultured Lymnaea stagnalis neurons, osmolarity increases (upshocks) rapidly elicited large membranous dilations that could be dislodged and pushed around inside the cell with a microprobe. Subsequent osmolarity decreases (downshocks) caused these vacuole-like dilations (VLDs) to disappear. Additional upshock/downshock perturbations resulted in repeated appearance/disappearance (formation/reversal) of VLDs at discrete sites. Confocal microscopy indicated that VLDs formed as invaginations of the substrate-adherent surface of the neuron: extracellular rhodamine-dextran entered VLDs as they formed and was expelled during reversal. Our standard VLD-inducing perturbation was: 2–4 min downshock to distilled water, upshock to normal saline. However, a wide range of other osmotic perturbations (involving osmolarities up to 3.5x normal, perturbations with or without Ca2+, replacement of ions by sucrose) were also used. We concluded that mechanical, not chemical, aspects of the osmo-mechanical shocks drove the VLD formation and reversal dynamics and that extracellular Ca2+ was not required. Following a standard perturbation, VLDs grew from invisible to their full diameter (〉10 μm) in just over a minute. Over the next 0.5–3 hr in normal saline, neurons recovered. Recovery eliminated any visible VLDs and was accompanied by cytoplasmic turmoil around the VLDs. Recovery was prevented by cytochalasin B, brefeldin A and N-ethylmaleimide but not by nocodazole. In striking contrast, these drugs did not prevent repeated VLD formation and reversal in response to standard osmo-mechanical perturbations; VLD disappearance during reversal and during recovery are different. The osmo-mechanical changes that elicited VLDs may, in an exaggerated fashion, mimic tension changes in extending and retracting neuntes. In this context we postulate: (a) the trafficking or disposition of membrane between internal stores and plasma membrane is mechano sensitive, (b) normally, this mechanosensitivity provides an “on demand” system by which neurons can accommodate stretch/release perturbations and control cell shape but, (c) given sudden extreme mechanical stimuli, it yields VLDs.

Electronic Resource

1432-1424

Osmotic shock ; Capacitance ; K conductance ; Contractility ; Volume ; Blebs

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Abstract Neurons are often regarded as fragile cells, easily destroyed by mechanical and osmotic insult. The results presented here demonstrate that this perception needs revision. Using extreme osmotic swelling, we show that molluscan neurons are astonishingly robust. In distilled water, a heterogeneous population of Lymnaea stagnalis CNS neurons swelled to several times their initial volume, yet had a ST50 (survival time for 50% of cells) 〉60 min. Cells that were initially bigger survived longer. On return to normal medium, survivors were able, over the next 24 hr, to rearborize. Reversible membrane capacitance changes corresponding to about 0.7 μF/cm2 of apparent surface area accompanied neuronal swelling and shrinking in hypo- and hyperosmotic solutions; reversible changes in cell surface area evidently contributed to the neurons' ability to accommodate hydrostatic pressures then recover. The reversible membrane area/capacitance changes were not dependent on extracellular Ca2+. Neurons were monitored for potassium currents during direct mechanical inflation and during osmotically driven inflation. The latter but not the former stimulus routinely elicited small potassium currents, suggesting that tension increases activate the currents only if additional disruption of the cortex has occurred. Under stress in distilled water, a third of the neurons displayed a quite unexpected behavior: prolonged writhing of peripheral regions of the soma. This suggested that a plasma membrane-linked contractile machinery (presumably actomyosin) might contribute to the neurons' mechano-osmotic robustness by restricting water influx. Consistent with this possibility, 1 mM, N-ethylmaleimide, which inhibits myosin ATPase, decreased the ST50 to 18 min, rendered the survival time independent of initial size, and abolished writhing activity. For neurons, active mechanical resistance of the submembranous cortex, along with the mechanical compliance supplied by insertion or eversion of membrane stores may account for the ability to withstand diverse mechanical stresses. Mechanical robustness such as that displayed here could be an asset during neuronal out-growth or regeneration.

Electronic Resource

0030-493X

Chemistry ; Analytical Chemistry and Spectroscopy

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

The ionic species [C12H11]+ has been formed by ion-molecule reactions in benzene at high pressure (˜0.5 Torr). This ion has been shown to be stable for at least 10-5 s and its structure has been inferred by a study of its unimolecular and collision induced fragmentations in both the first and second field free regions of the ZAB-2F mass spectrometer.

4 Tab.

Electronic Resource

0030-493X

Chemistry ; Analytical Chemistry and Spectroscopy

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

The fundamental processes of protonation and ethylation, occurring in a methane chemical ionization source, have been investigated for a variety of aromatic amines. The positions of protonation and ethylation on the substrate amines were determined by generating isomeric ions either by protonation of neutral ethyl substituted amines or by ethylation of the amines themselves. The product ions were investigated for structural differences via collision induced dissociation and subsequent analysis via mass analysed ion kinetic energy spectrometry. Similarities and differences between mass analysed ion kinetic energy/collision induced dissociation spectra of these isomeric ions were used to determine protonation and ethylation sites for imidazole, benzimidazole, indazole, pyrrole, pyridine and aniline.

3 Tab.

Electronic Resource