Search Results - (Author, Cooperation:R. J. Wood)

2015-05-29

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Biomimetics/*instrumentation ; Equipment Design ; Flight, Animal ; Manufacturing Industry ; Robotics/*instrumentation/trends ; *Technology/legislation & jurisprudence

2015-07-15

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

*Bioengineering ; Butanes ; Humans ; Leg/physiology ; *Locomotion ; Oxygen ; *Printing, Three-Dimensional ; *Robotics

2016-05-21

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2013-05-04

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; Biomechanical Phenomena ; *Biomimetic Materials ; *Diptera/anatomy & histology/physiology ; Drosophila/anatomy & histology/physiology ; *Flight, Animal ; Miniaturization ; Muscles/physiology ; *Robotics ; Wings, Animal/anatomy & histology/physiology

2015-08-01

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; Biomechanical Phenomena ; Extremities/physiology ; Heteroptera/*physiology ; Hydrodynamics ; *Locomotion ; Robotics ; Rotation ; Surface Tension ; *Water

2018-04-27

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Engineering, Online Only

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

An electrically heated wire-mesh apparatus for pyrolysis studies has been developed which uses computer-driven feedback control for the heating system and thus can apply virtually any time-temperature history to the sample. Internal components are water cooled to prevent heat buildup during long runs. Using this system, coal pyrolysis has been studied at heating rates from 0.1 to about 5000 K/s and temperatures up to 1000 °C. Alternating current is used for heating; this allows the thermocouples to be attached directly to the sample holder and also makes power regulation relatively simple. For atmospheric-pressure experiments, a gas sweep can be forced through the sample holder to remove products from the heated zone and also to concentrate them in a trap which can be removed from the apparatus and weighed to establish tar yields directly. Although the design is optimized for atmospheric-pressure operation, relatively simple modifications allow operation under vacuum or at pressures of up to 160 bars in inert gas or hydrogen. The apparatus has been used to investigate a number of phenomena in coal pyrolysis and, most significantly, has demonstrated the existence of a heating-rate effect which is independent of reactor geometry.

Electronic Resource

1365-2044

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1439-0264

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The ultrastructure of platelets was studied in specimens of peripheral blood from 18 healthy adult Arabian tahrs (Hemitragus jayakari). The platelets were characterized by their extreme polymorphism. The number of alpha granules, typically one to six per cell, was considerably less than that reported for most animal platelets. Similar to humans, the platelets of the Arabian tahr had nucleoids within the alpha granules. However, nucleoids were not a consistent finding. One or more electron-dense granules, most commonly contained within clear vesicles, was commonly observed. A unique feature was the lack of an open canalicular system, which is considered a hallmark feature of this cell type in most mammalian and reptilian platelets.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Oysters are able to seal off the perforations made by Urosalpinx ciherea Say. Dr. D. A. Hancock has kindly directed my attention to his observations2. He thinks the falling temperatures might have caused the oyster drills to abandon the attack. Oysters perforated with a hand drill completely sealed ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] SIR,-Though not directly connected with the Research Unit on Genetic Control of Mosquitoes in New Delhi, I have followed closely the progress of its research work and the recent unfortunate controversy which surrounded it. I would like to comment briefly on some of the points raised in the letter ...

Electronic Resource

1572-8838

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Electrical Engineering, Measurement and Control Technology

Abstract An electrochemical cell has been designed, based on a Cameron-Plint friction machine, which enables measurement of friction and wear under conditions of controlled potential. For mild steel in a pH 9 aqueous solution of sodium octanoate, varying the potential of the steel over the range −1 to + 1 V vs SHE produced three distinct friction-wear regimes: high friction/low wear, low friction/high wear, and low friction/low wear. These regimes were ascribed to potential dependent changes in the coverage and stability of a lubricating octanoate film on the surface of the steel. Increasing the contact stress amplified the effect of potential on wear, and confirmed that the surface film retained its lubricity at contact stresses capable of causing plastic deformation of the steel.

Electronic Resource

1572-9095

completely distributive ; adjunction ; projective ; nuclear ; Primary ; 06D10 ; Secondary ; 18B35 ; 03G10

Springer Online Journal Archives 1860-2000

Mathematics

Abstract A complete latticeL isconstructively completely distributive, (CCD), when the sup arrow from down-closed subobjects ofL toL has a left adjoint. The Karoubian envelope of the bicategory of relations is biequivalent to the bicategory of (CCD) lattices and sup-preserving arrows. There is a restriction to order ideals and “totally algebraic” lattices. Both biequivalences have left exact versions. As applications we characterize projective sup lattices and recover a known characterization of projective frames. Also, the known characterization of nuclear sup lattices in set as completely distributive lattices is extended to yet another characterization of (CCD) lattices in a topos.

Electronic Resource

1570-7458

Mediterranean fruit fly ; Ceratitis capitata ; mating activity ; courtship ; genetics ; startle activity ; quality control

Springer Online Journal Archives 1860-2000

Biology

Résumé Aucune variation significative n'a été observée dans les activités sexuelles de huit souches de laboratoire de la mouche méditerranéenne du fruit, Ceratitis capitata (Wiedemann) (Diptera Tephritidae). Deux méthodes ont été utilisées pour sélectionner des souches manifestant une activité sexuelle basse ou élevée: une technique utilisant un seul couple (SP), basée sur la durée de la période avant copulation, et une technique de masse (M), basée sur un ‘index d'accouplement’. Des appariements réciproques entre les lignées rapides et lentes ont montré que la différence entre les lignées SP était déterminée par les femelles, tandis que la différence entre les lignées M résultait du comportement des deux sexes. La sélection M, quelle que soit sa direction, affects deux paramètres, la ‘distance entre partenaires lors de la vibration’ et la ‘durée de la vibration’ qui tous deux tendent à se raccourcir. La sélection M est aussi associée à une réduction de la réaction des femelles à un brusque stimulus lumineux (‘Startle activity’).

Abstract No significant variation in mating activity was observed among eight laboratory strains of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Two methods were used to select strains showing high and low mating activity: a single pair technique (SP) assessing ‘time to mating’ and a mass technique (M) based on a ‘mating index’. Reciprocal pairings between fast and slow selected lines showed that the difference between the SP lines was female-determined whereas the difference between the M lines depended on the behaviour of both sexes. M selection, irrespective of its direction, affected two courtship parameters, ‘vibration distance’ and ‘vibration duration’ both of which tended to be shorter. M selection was also associated with a reduction in ‘startle activity’ in females.

Electronic Resource

1420-8911

Springer Online Journal Archives 1860-2000

Mathematics

Electronic Resource

1432-0886

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract A Giemsa C-banding technique applied to the mosquito, Aedes aegypti, has revealed a distinctive banding pattern which is described as a reliable means of distinguishing between the morphologically similar X and Y chromosomes during all stages of mitosis and meiosis. The essential difference is that the Y chromosome, unlike the X and the autosomes, is not C-banded in the centromere region. An intercalary band is also present in one arm of all X chromosomes and some Y chromosomes. The distribution of these cytological markers throughout meiosis indicates that the sex locus occurs somewhere within a pericentric region, the minimum extent of which includes both the intercalary band and the centromere.

Electronic Resource

1432-2072

Self-Stimulation ; Eating ; Drinking ; Dopamine ; Spiroperidol

Springer Online Journal Archives 1860-2000

Medicine

Abstract Spiroperidol, which blocks dopamine (DA) receptors, attenuated self-stimulation of the nucleus accumbens, septal area, hippocampus, anterior hypothalamus and ventral tegmental area. Dopamine is thus involved in self-stimulation of many sites (in addition to the lateral hypothalamus). The attenuation was not a simple motor impairment of the speed of bar-pressing in that the nucleus accumbens and septal self-stimulation rates were lower than those in treated animals self-stimulating at other sites (Experiment 1). Feeding was partly attenuated, and drinking was much less attenuated by the spiroperidol. Since the rats bar-pressed for brain-stimulation reward, chewed pellets to eat, and licked a tube to drink, dopamine-receptor blockade may attenuate complex motor responses most. Alternatively, the blockade could affect brain-stimulation reward more than the controls of eating, and these latter more than the controls of drinking (Experiment 2). In Experiment 3, feeding and drinking were equally and severely attenuated when rats had to bar-press to obtain food or water. The attenuation was to a level similar to that found for self-stimulation. These experiments suggest that dopamine receptor blockade impairs eating, drinking and self-stimulation by interfering with complex motor responses.

Electronic Resource

1573-6857

Springer Online Journal Archives 1860-2000

Biology

Sex ratio in the Trinidad (T-30) strain of Aedes aegypti has remained constant at around 43%♀ during seventeen years of laboratory culture. The divergence from 50% is due to meiotic drive by the M D gene on the Y chromosome. The driving Y chromosome gives a much more distorted sex ratio (mean = 5.7%♀) when coupled with the highly sensitive X chromosomes from strain 64. This was demonstrated in all of 98 families tested, indicating that all or most of the Y chromosomes in T-30 carry the M D gene. Consequently the low level of sex ratio distortion in T-30 must be due to resistance to M D. Crosses made within T-30 demonstrated wide differences in sex ratio between families, depending on the sensitivity of the male parent's X chromosome to M D. However, sex ratios were not continuously variable but fell within fairly discrete categories. Thus, X chromosomes could be classified according to the modal sex ratios associated with them: m s3 (12.5%♀), m s2 (32.5%♀), m s1 (40%♀), m r1 (47.5%♀) m r2 (57.5%♀). The different sex ratio categories were more discrete in the families of sib matings than from random matings, suggesting the possibility of background modification of what is essentially a balanced polymorphism. Evidence is presented suggesting that the polymorphism could be due to interaction at two loci. A further X variant, m s4 (〈10%♀) characterised strain 64 but was absent from T-30. A comparison of fertility between the different sex ratio categories in T-30 established that sex ratio distortion was not caused by differential mortality after fertilisation.

Electronic Resource

1573-6857

Springer Online Journal Archives 1860-2000

Biology

The separate identities of the male-determining factor, M, and the sex-linked Distorter gene, D, are established in an Accra strain of Aedes aegypti. Their to each other and to Giemsa C-bands. Thus, M is invariably inherited with the centromere, whereas D lies towards the intercalary band. Approximately 1.2% recombination occurs between M and D but, in a chromosome known for its distal localization of chiasmata, it is argued that he two are not necessarily as closely linked cytologically as this might imply. Evidence on the genetic effects of recombination in the region of M and D is also considered.

Electronic Resource

1573-6857

Springer Online Journal Archives 1860-2000

Biology

Electronic Resource