bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue behavior of filament‐wound glass fiber reinforced epoxy composite tubes under tension/torsion biaxial loading
Authors: Qi Dongtao , Cheng Guangxu
Published: January 2007

A study of filament‐wound glass fiber/epoxy composite tubes under biaxial fatigue loading is presented. The focus is placed on fatigue lives of tubular specimens under tension/torsion biaxial loading at low cycle up to 100,000 cycles. Filament‐wound glass‐fiber/epoxy tubular specimens with three different lay‐up configurations, namely [±35°]n, [±55°]n, and [±70°]n lay‐ups, are subjected to in‐phase proportional biaxial cyclic loading conditions. The effects of winding angle and biaxiality ratio on the multiaxial fatigue performance of composites are discussed. Specimens are also tested under two cyclic stress ratio: R = 0 and R = −1. The experimental results reveal that both tensile and compressive loading have an influence on the multiaxial fatigue strength, especially for [±35°]n specimens. A damage model proposed in the literature is applied to predict multiaxial fatigue life of filament‐wound composites and the predictions are compared with the experimental results. It is shown that the model is unsuitable for describing the multiaxial fatigue life under different cyclic stress ratios. POLYM. COMPOS. 28:116–123, 2007. © 2007 Society of Plastics Engineers
Thermally conductive silicone rubber reinforced with boron nitride particle
Authors: Zhou Wen‐Ying , Qi Shu‐Hua , Zhao Hong‐Zhen , Liu Nai‐Liang
Published: January 2007

Thermally conductive silicone rubber used as elastomeric thermal pad is successfully developed with boron nitride powder as conductive filler. The effects of content and particle size of filler on the thermal conductivity and mechanical property of silicone rubber are investigated. The results indicate that the use of hybrid boron nitride with three different particle sizes at a preferable weight ratio gives silicone rubber better thermal conductivity compared with each boron nitride with single particle size at the same total filler content. Furthermore, scanning electron microscopy, differential scanning calorimeter, thermogravimetric, etc., are used to characterize the morphology, curing behavior, thermal stability, and coefficient of thermal expansion (CTE) of the silicone rubber composites. POLYM. COMPOS., 28:23–28, 2007. © 2007 Society of Plastics Engineers
Perspectives on main‐chain hydrogen bonded supramolecular polymers
Authors: Shimizu Linda S
Published: January 2007

Supramolecular polymers are assembled from monomeric units held together by reversible non‐covalent interactions. These supramolecular materials display polymeric properties and may soon have important industrial applications. This mini review focuses on the advances in main‐chain supramolecular polymers whose assembly is guided primarily by hydrogen bonding interactions. The design constraints of these new systems discussed include assembly motifs, the strength and directionality of the non‐covalent interactions, association versus reversibility, and environmental effects on the degree of polymerization. Selected literature examples including Meijer's ureidopyrimidinone system are used to highlight the challenges and potential of these supramolecular polymeric materials. Copyright © 2007 Society of Chemical Industry
Peer victimization and prosocial experiences and emotional well‐being of middle school students
Authors: Martin Kellie M. , Huebner E. Scott
Published: January 2007

This study investigated the relationships among different forms of peer victimization and prosocial experiences and early adolescent emotional well‐being. A total of 571 students in grades 6–8 were administered the Positive and Negative Affect Scale–Children, Multidimensional Students' Life Satisfaction Scale, and the Children's Self Experience Questionnaire–Self Report. Females reported more prosocial experiences; males reported more overt and relational victimization. Differential predictors were observed for the emotional well‐being variables of life satisfaction, positive affect, and negative affect in a series of hierarchical multiple regression equations. Overt victimization experiences added significant variance to all three well‐being equations. Relational victimization experiences added significant variance to the negative affect equation. After accounting for overt and relational experiences, prosocial experiences added significant variance to the life satisfaction and positive affect equations. The experience of prosocial peer interactions thus appears to serve as a protective factor with respect to the relationship between victimization and life satisfaction and positive affect for early adolescents. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 199–208, 2007.
Fatal asthma in finnish children and adolescents 1976–1998: Validity of death certificates and a clinical description
Authors: Malmström Kristiina , Kaila Minna , Kajosaari Merja , Syvänen Pirkko , Juntunen‐Backman Kaisu
Published: January 2007

Several studies show that asthma mortality in children and adolescents increased until the mid‐1990s, after which it has slightly decreased worldwide. The objective of this study was to describe the mortality rates of childhood asthma in Finland, and to analyze patient characteristics to identify predisposing factors for fatal asthma exacerbation among children and adolescents during 1976–1998 (2004). All death certificates where asthma or related respiratory tract disease was coded as the underlying cause of death were reviewed for those under 20 years of age. Health care records and autopsy reports were evaluated to validate the cause of death and to identify any predisposing factors. In all, there had been 28 asthma deaths. The validity of the death certificates proved to be good as only 7% were misclassified. Death occurred either in the very young children or adolescents: the median age in the group of <12 years (n = 15) was 3.3 years while the median age in the group of >12 years (n = 13) was 18.1 years. The fatal exacerbations occurred mostly during summer and early autumn. Clinical triggers, recorded for 14/22 patients with available patient records, included respiratory infection, (12) use of ibuprofen despite known allergy (1), and exercise after visiting a horse stable (1). The severity of the disease was discernible in 21 patients: severe in 15, moderate in 5, and mild in 1 patient. Inhaled corticosteroids were not used as maintenance or periodic therapy in 12/22 patients, of whom 4 had died during the 1990s. In conclusion, asthma mortality in Finnish children and adolescents was rare and its incidence remained stable. The validity of the death certificate diagnoses proved to be good. Poor asthma management and non or undertreatment with inhaled corticosteroids were risk factors for fatal asthma. Pediatr Pulmonol. 2007; 42:210–215. © 2007 Wiley‐Liss, Inc.
Can direct field‐evaporation of doubly charged ions and post‐ionisation from the singly charged state co‐exist?
Authors: Ganetsos Th. , Mair A. W. R. , Mair G. L. R. , Bischoff L. , Akhmadaliev Ch. , Aidinis C. J.
Published: January 2007

A tin liquid metal ion source (LMIS) containing ∼14% Pb has been studied. From a careful examination of the mass spectra of the source, it is concluded that post‐ionisation (PI) is the most probable mechanism for the formation of Pb2+ ions. In the case of tin, however, both Sn+ and Sn2+ appear to form by direct field‐evaporation. This view is supported by energy deficit measurements on the Sn+ and Sn2+ beams. Our results for Pb2+/Pb+ agree with those of Komuro with a pure Pb source. The reason for this is understandable and is related to the similarity between the evaporation fields of Sn and Pb. For the sake of completeness, we also present measurements of the energy spread of the Sn2+ and Sn+ beams. Copyright © 2007 John Wiley & Sons, Ltd.
The current stability of field emission cathodes of carbon nanotubes under ion bombardment
Authors: Bormashov Vitaly S. , Baturin Andrey S. , Nikolskiy Konstantin N. , Tchesov Roman G. , Sheshin Evgeniy P.
Published: January 2007

The degradation mechanism of field emission cathodes based on carbon nanotubes was investigated in the presented work. Emission current instability came from the adsorption/desorption processes on the cathode surface. During the long‐time tests, periodical variation of the electron work‐function (caused by switching on and off of the cathode) was detected. A model is proposed to explain the experimentally observed variations of electron work‐function. Copyright © 2007 John Wiley & Sons, Ltd.
Field emission from metal/polymer construction
Authors: Ionov A. N. , Popov E. O. , Svetlichnyi V. M. , Nikolaeva M. N. , Pashkevich A. A.
Published: January 2007

We investigated a large number of polymer materials. The parameters affecting their emission properties (namely, film thickness, temperature of polymer preparation, metal substrates and so on) were studied. We observed that the emission distributed over the full polymer surface with current densities up to several hundreds of µA/cm2. Some polymer samples showed high current emission properties up to 50 µA in d.c. and more than 1.5 mA in sinusoidal regimes. Copyright © 2007 John Wiley & Sons, Ltd.
Early stages of phase separation using three‐dimensional atom probe and atomistic modelling
Authors: Slabanja Mattias , Angenete Johan , Stiller Krystyna , Carling Karin M. , Wahnström Göran , Andrén Hans‐Olof
Published: January 2007

The early stages of clustering in Al‐14.8 Mg alloy have been studied using atomistic modelling and 3DAP analysis. Atomistic modelling was based on first‐principles quantum mechanical calculations and Monte Carlo (MC) based techniques. A good agreement between the experimental results and simulated data was obtained showing the appropriateness of the theoretical approach used. It has been shown that after 720 h at 35 °C (308 K) clustering of Mg was clearly detectable in the experimental alloy. The simulated data after 200 MC steps corresponded well to the experimental results obtained after ageing for 720 h. Copyright © 2007 John Wiley & Sons, Ltd.
Performance of a local electrode atom probe
Authors: Miller M. K. , Russell K. F.
Published: January 2007

The performance of a local electrode atom probe with a crossed delay line detector has been characterized. The local electrode atom probe with its short flight path and high speed (up to 250 kHz) pulse generator has made dramatic, orders of magnitude improvements in the data acquisition rate and the size of the analyzed volume compared to previous types of three‐dimensional atom probes. Sustained detection rates of up to 17% ions per field evaporation pulse have been achieved with data collection rates of up to 2 million atoms per minute. Preferential evaporation is substantially reduced due to the smaller proportion of time spent at the standing voltage enabling lower pulse fractions to be routinely used. A procedure for aligning the specimen with the aperture in the local electrode is described. Published in 2007 by John Wiley & Sons, Ltd.
Pain‐related self‐efficacy beliefs in a Brazilian chronic pain patient sample: a psychometric analysis
Authors: Sardá Jamir , Nicholas Michael K. , Pimenta Cibele A. M. , Asghari Ali
Published: January 2007

While some people become severely or moderately disabled by chronic pain (pain that persists >3 months), others seem to adjust reasonably well to it. Higher levels of disability are often associated with higher levels of distress, and this relationship can be bidirectional resulting in a vicious cycle. There is evidence suggesting that self‐efficacy is one of the most important contributors to disability and emotional adjustment to chronic pain. Defining pain self‐efficacy beliefs as confidence in ability to function despite pain, the Pain Self‐Efficacy Questionnaire (PSEQ) has been widely used to examine the role of self‐efficacy in chronic pain patient populations. However, to date it has not been validated in Brazil. This study examined the reliability and validity of the PSEQ in a Brazilian chronic pain population. Data were collected from a convenience sample of 348 chronic pain patients. Reliability of the PSEQ has been found to be adequate (split‐half correlation was 0.76 and internal consistency was 0.90). Factor analysis indicated the existence of only one factor. Discriminant and concurrent validity were also adequate. Altogether these results indicate that the PSEQ has good psychometric properties when used in this sample. These findings are also consistent with those previously published in the literature. Copyright © 2007 John Wiley & Sons, Ltd.
Docking onto chromatin via the Saccharomyces cerevisiae Rad9 Tudor domain
Authors: Grenon Muriel , Costelloe Thomas , Jimeno Sonia , O'Shaughnessy Aisling , FitzGerald Jennifer , Zgheib Omar , Degerth Linda , Lowndes Noel F.
Published: January 2007

An integrated cellular response to DNA damage is essential for the maintenance of genome integrity. Recently, post‐translational modifications to histone proteins have been implicated in DNA damage responses involving the Rad9 family of checkpoint proteins. In budding yeast, methylation of histone H3 on lysine 79 (H3‐K79me) has been shown to be required for efficient checkpoint signalling and Rad9 localization on chromatin. Here, we have used a rad9 Tudor mutant allele and cells mutated for Dot1, the H3‐K79 methylase, to analyse the epistatic relationship between RAD9 and DOT1 genes regarding the DNA damage resistance and checkpoint activation pathways. Our results show that RAD9 is epistatic to DOT1 and suggest that it acts downstream of the Dot1 methylase in the damage resistance and checkpoint response. We have also found that the Tudor domain of Rad9 is necessary for in vitro binding to H3‐K79me as well as Rad9 focal accumulation in response to DNA damage in vivo. In summary, our study demonstrates that the interaction between Rad9, via its Tudor domain, and methylated H3‐K79 is required at two different steps of the DNA damage response, an early step corresponding to checkpoint activation, and a late step corresponding to DNA repair. The study further shows that the function of this interaction is cell cycle‐regulated; the role in checkpoint activation is restricted to the G1 phase and its role in DNA repair is restricted to G2. Copyright © 2007 John Wiley & Sons, Ltd.
Electrochemical properties of double wall carbon nanotube electrodes
Authors: Pumera Martin
Published: January 2007

Electrochemical properties of double wall carbon nanotubes (DWNT) were assessed and compared to their single wall (SWNT) counterparts. The double and single wall carbon nanotube materials were characterized by Raman spectroscopy, scanning and transmission electron microscopy and electrochemistry. The electrochemical behavior of DWNT film electrodes was characterized by using cyclic voltammetry of ferricyanide and NADH. It is shown that while both DWNT and SWNT were significantly functionalized with oxygen containing groups, double wall carbon nanotube film electrodes show a fast electron transfer and substantial decrease of overpotential of NADH when compared to the same way treated single wall carbon nanotubes.
Influence of soaking, fermentation and phytase supplementation on nutrient digestibility in pigs offered a grower diet based on wheat and barley
Authors: Lyberg K. , Lundh T. , Pedersen C. , Lindberg J. E.
Published: January 2007

The effects of 1-h soaking, fermentation and phytase supplementation of a pig diet based on wheat and barley on ileal and total tract apparent digestibility in growing pigs fitted with a post valve T-caecum (PVTC)-cannula were studied. Eight animals in a two-period change-over design were used, subjecting four animals to each treatment (dry, soaked, microbial phytase supplemented or fermented diet). Acid insoluble ash was used as an indigestible marker for calculating apparent digestibility coefficients. Fermentation improved (P<0·05) the ileal apparent digestibility coefficients of organic matter (OM), nitrogen and amino acids, while there was no effect of 1-h soaking and phytase supplementation. The total tract apparent digestibility coefficient of OM was also improved by fermentation. The ileal apparent digestibility coefficient of phosphorus (P) was higher for fermentation (P<0·05) than for dry food and 1-h soaking. The total tract apparent digestibility coefficient of P was higher (P<0·05) for treated food (soaked, fermented and supplemented with microbial phytase) compared with dry food. Fermentation improved (P<0·05) the ileal apparent digestibility coefficient of calcium compared with dry and soaked food, and had no effect on the total tract apparent digestibility coefficient of calcium. Food inositol phosphates were affected by treatment (P<0·05), with a reduction of P bound to inositol hexaphosphate (IP6) of 10% in the 1-h soaked food and of 80% in the fermented food. Degradation of IP6in the gastro-intestinal tract of the animals was lower in the fermented food than in the other treatments. The content of neutral-detergent fibre in the food was reduced (P<0·05) in the soaked and fermented food by 4% and 14%, respectively, compared with the dry food. In conclusion, fermentation of food can improve digestibility of OM, degrade IP6and increase ileal digestibility of phosphorus, nitrogen and amino acids.
Dose effect of live yeasts on rumen microbial communities and fermentations during butyric latent acidosis in sheep: new type of interaction
Authors: Brossard L. , Chaucheyras-Durand F. , Michalet-Doreau B. , Martin C.
Published: January 2007

Six ruminal cannulated Texel sheep were used to assess the dose response and the effect of live yeasts (Levucell® SC, Saccharomyces cerevisiae CNCM I-1077) on the prevention of induced ruminal latent acidosis. The sheep received, in a replicated 3×3 Latin-square design, an acidotic diet (wheat +lucerne hay, 60:40 (dry matter (DM) basis); starch: 410 g/kg DM) without yeast (control group; L0 treatment), supplemented with 0·2 g/day yeast (4×109colony-forming units (c.f.u.) per day corresponding to producer recommendations; L1 treatment) or with 2 g/day yeast (4×1010c.f.u. per day; L10 treatment). The following measurements were carried out: food intake, ruminal pH, ruminal volatile fatty acids (VFA), lactate and ammonia (NH3) concentrations, protozoal and lactate-utilizing bacterial counts, relative proportions of two main bacteria implicated in lactate metabolism (a lactate-producing species, Streptococcus bovis, and a lactate-utilizing species, Megasphaera elsdenii) using specific 16S-rRNA-targeting oligonucleotide probes, activities of lactate dehydrogenase (LDH) and of polysaccharidases involved in plant cell wall (xylanase, carboxymethylcellulase) and starch (amylase) degradation. The acidotic diet (L0) induced a butyric (12 mol per 100 mol total VFA) rather than lactic (<4 mmol/l) ruminal latent acidosis. Ruminal pH, fermentative patterns, lactate-metabolizing bacteria (concentration, LDH activity) and polysaccharidase activities were similar between treatments (P>0·1). Yeast supplementation tended to increase ruminal protozoal population (P<0·1) and intake of animals (P<0·1). The recommended yeast concentration (L1) was sufficient to ensure these effects. The yeast's action may differ according to the nature and function of the micro-organisms involved and the type of fermentative pattern favoured (protozoa/butyrate v. lactate-metabolizing bacteria/lactate and propionate) during ruminal acidosis in sheep.
Low-pressure flashing mechanisms in iso-octane liquid jets
Authors: VIEIRA M. M. , SIMÕES-MOREIRA J. R.
Published: January 2007

This paper examines a flashing liquid regime that takes place at very high ratios of injection to discharge pressures in flow restrictions. Typically, the flashing phenomenon has been observed in laboratory experiments where a liquid flows through a short nozzle into a low-pressure chamber at a pressure value considerably lower than the liquid saturation pressure at the injection temperature. By using two visualization techniques, the schlieren and the back-lighting methods, it was possible to identify some compressible phenomena associated with the liquid flashing process from the nozzle exit section. The schlieren method was used to capture the image of a shock-wave structure surrounding a liquid core from which the phase change takes place, and the optical technique allowed us to observe the central liquid core itself. The work corroborates previous physical descriptions of flashing liquid jets to explain an observed choking behaviour as well as the presence of shock waves. According to the present analysis, flashing takes place on the surface of the liquid core through an evaporation wave process, which results from a sudden liquid evaporation in a discontinuous process. Downstream of the evaporation discontinuity, the two-phase flow reaches very high velocities, up to the local sonic speed that typically occurs at high expansion conditions, as inferred from experiments and the physical model. That sonic state is also a point of maximum mass flow rate and it is known as the Chapman–Jouguet condition. The freshly sonic two-phase flow expands freely to increasing supersonic velocities and eventually terminates the expansion process through a shock-wave structure. This paper presents experimental results at several test conditions with iso-octane.
On the effects of microbubbles on Taylor–Green vortex flow
Authors: FERRANTE ANTONINO , ELGHOBASHI SAID E.
Published: January 2007

The paper describes a numerical study of the effects of microbubbles on the vorticity dynamics in a Taylor–Green vortex flow (TGV) using the two-fluid approach. The results show that bubbles with a volume fraction ∼10−2 enhance the decay rate of the vorticity at the centre of the vortex. Analysis of the vorticity equation of the bubble-laden flow shows that the local positive velocity divergence of the fluid velocity, ∇·U, created in the vortex core by bubble clustering, is responsible for the vorticity decay. At the centre of the vortex, the vorticity ωc(t) decreases nearly linearly with the bubble concentration Cm(t). Similarly, the enstrophy in the core of the vortex, ω2(t), decays nearly linearly with C2(t). The approximate mean-enstrophy equation shows that bubble accumulation in the high-enstrophy core regions produces a positive correlation between ω2 and ∇·U, which enhances the decay rate of the mean enstrophy.
A tangled affair: pacemaker malfunction and syncope in a child due to Twiddler's syndrome
Authors: Ellis Alexander R. , Reed John H. , Fairbrother David
Published: January 2007

Manipulation of an implanted pacemaker by the patient is a rare cause of malfunction, especially in children. We describe a child who inadvertently rotated his pacemaker under the skin, knotting the leads and dislodging them from the heart, leading to syncope and heart block. Our experience with this case underscores the need to consider this diagnosis in children as well as in adults if this problem is to be averted.
Influence of chronic intrauterine exposure to alcohol on structurally normal hearts
Authors: Krasemann Thomas , Klingebiel Sandra
Published: January 2007

Abuse of alcohol during pregnancy is known to cause alcoholic embryopathy and congenital cardiac disease. We sought to establish if there were any cardiac abnormalities to be found in patients known to have alcoholic embryopathy, but with structurally normal hearts. We reviewed the electrocardiograms and echocardiographic data of 347 such patients without congenital cardiac disease. A shortened QT interval was found in half of the cases. The left ventricular diameter was small in one quarter of all patients, independent from age, gender, and the degree of alcoholic embryopathy. We conclude that intrauterine exposure to alcohol as a primary toxin can lead to minor cardiac abnormalities, even in the absence of structural congenital cardiac disease.
Acetaminophen potentiates staurosporine‐induced death in a human neuroblastoma cell line
Authors: Posadas I , Vellecco V , Santos P , Prieto‐Lloret J , Ceña V
Published: January 2007

Background and purpose:

Neuroblastoma is the most common solid tumour in infants characterized by a high resistance to apoptosis. Recently, the cyclo‐oxygenase pathway has been considered a potential target in the treatment of different kinds of tumours. The aim of the present work was to investigate a possible relationship between cyclo‐oxygenase pathway and stauroporine‐induced apoptosis in the neuroblastoma cell line SH‐SY5Y.

Experimental approach:

Cellular viability was measured by release of LDH. DNA fragmentation was visualized by electrophoresis on agarose gel containing ethidium bromide. Cyclo‐oxygenase activity was measured in microsomal fractions obtained from cells by quantification of its final product PGE2by RIA. Caspase‐3 activity was measured fluorimetrically and Western blot analysis was performed to assess cytochrome c expression.

Key results:

We have found that staurosporine (500 nM) induced cellular death in a time‐dependent manner in SH‐SY5Y human neuroblastoma cells. Cyclo‐oxygenase enzymatic activity was present in SH‐SY5Y human neuroblastoma cells under basal conditions and pharmacological experiments using COX inhibitors indicate that cyclo‐oxygenase‐1 and cyclo‐oxygenase‐3 are the active isoforms in these cells. Co‐incubation of SH‐SY5Y cells with staurosporine (500 nM) and acetaminophen for 24 h potentiated staurosporine‐mediated cellular death in a concentration‐dependent manner. This process is mediated by an increase in cytochrome c release and caspase 3 activation and is prevented by N‐acetylcysteine or the superoxide dismutase mimetic, MnTBAP.

Conclusions and implications:

Acetaminophen potentiates staurosporine‐mediated neuroblastoma cell death. The mechanism of action of acetaminophen seems to be related to production of reactive oxygen species and decreased intracellular glutathione levels.

British Journal of Pharmacology(2007)150, 577–585. doi:10.1038/sj.bjp.0706993
Effects of chronic nitric oxide synthase inhibition on the cardiovascular responses to cannabinoids in vivo and in vitro
Authors: Wheal A J , Bennett T , Randall M D , Gardiner S M
Published: January 2007

Background and purpose:

Since the vasorelaxant potency of the endocannabinoid anandamide is enhanced in perfused mesenteric vascular beds from rats made hypertensive by chronic inhibition of NO synthase (L‐NAME in drinking water), we hypothesized that in vivo, anandamide‐induced vasodilatation would be similarly enhanced in L‐NAME‐treated animals.

Experimental approach:

Male Sprague‐Dawley rats were given L‐NAME in drinking water (7.5 mg kg−1 day−1) for 4 weeks. Relaxant effects of anandamide were measured in perfused mesenteric vascular beds and in isolated small mesenteric arteries. Renal, mesenteric and hindquarters haemodynamic responses to anandamide, methanandamide, the synthetic cannabinoid agonist WIN‐55212‐2 and the cannabinoid receptor antagonist AM251 were assessed in conscious, chronically‐instrumented rats.

Key results:

Vasorelaxant responses to anandamide were enhanced in the perfused mesentery but not in isolated mesenteric resistance vessels. In vivo, anandamide caused vasodilatation only in the hindquarters vascular bed and only in control rats. Methanandamide caused a late‐onset (40 min after administration) tachycardia, mesenteric and hindquarters vasoconstriction, and renal vasodilatation, which did not differ between control and L‐NAME‐treated rats. AM251 had no effect on resting blood pressure in control or L‐NAME‐treated rats and WIN55212‐2 caused pressor and renal and mesenteric vasoconstrictor responses, with hindquarters vasodilatation in both groups of animals.

Conclusions and Implications:

The results provide no in vivo evidence for enhanced vasodilator responses to cannabinoids, or up‐regulation of endocannabinoids or their receptor activity, following chronic NO synthase inhibition.

British Journal of Pharmacology (2007) 150, 662–671. doi:10.1038/sj.bjp.0707136
Carbon-assisted water electrolysis: An energy-efficient process to produce pure H2 at room temperature
Authors: Seehra M. S. , Ranganathan S. , Manivannan A.
Published: January 2007

The authors report on carbon-assisted water electrolysis at 300K which only consumes 9.6kcal∕mol H2O (compared to 56.7kcal∕mol H2O for ordinary electrolysis) using the net reaction C(s)+2H2O(ℓ)→CO2(g)+2H2(g). Carbon-assisted H2 production and its kinetics/energetics are measured at applied potential ∣E0∣ between 0.1 and 1.8V (compared to ∣E0∣ >1.25V required for water electrolysis). Surprisingly, H2 produced per W h is higher at the lower voltages, but longer times are required to produce the same amount of H2 The suggested practical conditions are ∣E0∣≃0.5V and carbon concentration of 0.08g∕cm3.
Low transparency current density and high temperature operation from ten-layer p-doped 1.3μm InAs∕InGaAs∕GaAs quantum dot lasers
Authors: Liu C. Y. , Yoon S. F. , Cao Q. , Tong C. Z. , Li H. F.
Published: January 2007

High temperature photoluminescence up to 100°C was demonstrated from the p-doped ten-layer InAs∕InGaAs quantum dot (QD) laser structure. 1.3μm InAs QD lasers were fabricated using pulsed anodic oxidation from this structure. High output power of 882mW and low transparency current density of 5.9A∕cm2∕QD layer were obtained. Ground state (GS) lasing could be maintained from a QD laser with short cavity length of 611μm, corresponding to the maximum modal gain of 23.1cm−1 from this laser system. GS continuous wave operation up to 100°C was also demonstrated from an InAs QD laser (50×2500μm2).
A Cyclic Decision Model of Perceptual Alternation
Authors: Vickers D
Published: January 2007

Six general features of perceptual reversals or alternations are described, and an explanation is proposed in terms of the cyclic repetition of an optional stopping decision process. The properties of this model are found to correspond closely to the general features of perceptual alternation, and the account seems capable of explaining several related findings as well as reconciling some apparent conflict between previous results.
Stimulus Pairing in Sequential Phi Motion
Authors: Lee D N
Published: January 2007

Two correlated random-dot Julesz patterns, that produce apparent lateral motion of a textured surface when flashed once in succession at an appropriate ISI, were flashed repetitively in temporal alternation. If the two ISI's in the stimulus sequence were each appropriate to apparent motion, perceived to-and-fro motion of the textured surface would be expected. It was found, however, that, when the two ISI's were sufficiently different, continuous unidirectional flow-motion was perceived, indicating that the visual system was effectively partitioning the stimulus sequence into a series of identical ‘phi-pairs’ on the basis of the shorter ISI. The temporal limits of the phenomenon were investigated. Binocular, binaural, and tactile analogues of this phenomenon of perceptual pairing of successive stimuli according to temporal proximity are discussed.
Adaptation-Level Theory and Context Effects on Sensory Judgments: Perception or Response?
Authors: Ellis H D
Published: January 2007

The evidence in favour of Helson's (1947, 1964) contention that context effects are the result of alterations in sensory excitability is reviewed. In particular Steven's (1958) criticism of category scaling, as a technique for establishing such context effects, is examined as well as the experimental evidence supporting it. These studies are not considered conclusive proof that such effects are solely mediated by response processes. Other evidence suggests that there is a perceptual component, and that therefore Helson's Adaptation Level Theory—a single factor theory—is probably oversimplified, since context effects appear to reflect a number of factors both perceptual and response based. The inappropriateness of analysing context effects by means of statistical decision theory is discussed.
Réponses évoquées par les mouvements oculaires d'exploration (réponse lambda): Rôle des afférences intervenant à divers moments du processus oculo-moteur
Authors: Lesèvre Nicole , Rémond A
Published: January 2007

Experiments are reported the aim of which was to elucidate the cause of each of the components of the lambda response, and particularly to evaluate the role of ‘on’ and ‘off’ visual effects which appear at various times during the oculomotor process and also the possible influence of non-visual mechanisms.

Eight subjects with normal sight were studied under the following conditions: (i) horizontal eye movements of 12° were guided by fixation points placed on a dimly-lit uniform black field of 20°; a checkerboard of 6° aperture was placed in this field so as to be integrated into the oculomotor process at different times—at the beginning, during and at the end of the eye movement; (ii) successive horizontal eye movements of 3°, 7° and 11° scanned a checkerboard of 20°, each square of which had a 40′ aperture; (iii) the checkerboard was moved with an amplitude and period similar to those of the eye movements in (ii), but this time with gaze fixed. Horizontal and vertical movements of both eyes were recorded with an EOG. An EEG of the parieto-occipital regions was obtained using eight linked bipolar derivations in line on two montages, median longitudinal and right-left transverse. The EEG and EOG data were digitalized and a numerical programme of waveform recognition was used to identify the beginning of the saccade which triggers the averaging out of the EEG before (100 ms) and after (500 ms) the eye movement.

A discussion of the results, taking into account the latency of the different components and their reinforcements or inhibition depending on experimental conditions, suggests that the two initial components of lambda response (including the initial portion of the classical lambda wave) might be due to visual effects (‘off effect’) that arise at the start of the movement or slightly before it at the time that the saccadic suppression begins. The later components could be attributed to visual effects brought into play towards the end of the movement (‘on effect’), when perception becomes normal again. It is, however, difficult to explain some of the results related to the amplitude of lambda components without bringing in a mechanism of non-visual origin (corollary discharge).
Réponses évoquées par le nystagmus spontané
Authors: Lairy Gabrielle C , Lesèvre Nicole , Baillon J F , Rémond A , Godde-Jolly D
Published: January 2007

A digital programme of wave form recognition was applied to a nystagmogram so as to pave the way for an average chronotopographic study of the occipital EEG activity triggered by the start of the rapid stage of the nystagmus. The programme was used in a clinical case of congenital nystagmus associated with a visual deficiency (coloboma of the optic nerve), with the following results: (i) in the patient examined, no average evoked response was observed either with eyes closed or with eyes open in the dark; (ii) an average response of small amplitude was observed with eyes open centred on a homogeneous illuminated field; this response was reinforced (greater amplitude and more complex structure) by a patterned field (checkerboard); (iii) the response to nystagmus showed characteristics similar to those of lambda response in the same subject.

These results appear to confirm the conclusions of Bender and Shanzer (1964) according to which the calcarine activity in monkeys in response to experimental nystagmus is “light and vision dependent and correlates with the visual input and not with the oculomotor output”.

Differences in amplitude, latency, and structure between the various responses recorded in the patient examined (response to nystagmus, to appearance of lighted checkerboard, and lambda response) and the same responses in normal subjects are considered and discussed in relation to factors associated with visual deficiency.
Figural Aftereffects in Random-Dot Stereograms without Monocular Contours
Authors: Walker J T , Kruger M W
Published: January 2007

Random-dot stereograms produced contour-displacement figural aftereffects in the absence of monocular inspection and test contours. Such aftereffects are wholly cyclopean (central), since no interaction between inspection and test contours could occur at any level lower than the area of binocular fusion. Cyclopean aftereffects have important implications for theories of figural aftereffects.
An Investigation of Visual Orientation Constancy Using Orientation-Specific Properties of Acuity and Adaptation
Authors: Findlay J M , Parker D M
Published: January 2007

Recent neurophysiological studies have suggested that orientation constancy might be achieved by the action of a compensatory signal from the vestibular system operating at the level of the visual cortex. Two experiments were carried out in an attempt to find psychophysical evidence for such a system. In the first the variation of visual acuity with stimulus orientation was measured as the subject's head was tilted through 45°, and in the second the orientation specific adaptation to gratings of Blakemore and Campbell (1969) was similarly studied. The results showed that both visual discriminations were dependent upon the retinal properties of the stimulus only; in other words no effect of phenomenal orientation could be detected.
Electrophysiological and Psychophysical Responses to Modulation of Contrast of a Grating Pattern
Authors: Bodis-Wollner I , Hendley C D , Kulikowski J J
Published: January 2007

Contrast-modulated grating patterns were used to compare evoked responses and psychophysical thresholds of contrast modulation. The stimulus consisted of the successive presentation of a grating pattern at a higher and lower contrast. At a modulation rate of 8 Hz it was found that there is correspondence between the two kinds of data for a 6 cycle/degree grating. The just noticeable difference was not constant, and data approximated a Weber's law of contrast discrimination. However, it was found that there is a slight departure from this law, in that the ratio decreases with mean contrast. Both psychophysical and electrophysiological data exclude a model of simple luminance detection and are consistent with the operation of spatial contrast detectors in the human visual system.
Interocular Transfer in Normal Humans, and Those Who Lack Stereopsis
Authors: Movshon J A , Chambers B E I , Blakemore C
Published: January 2007

Interocular transfer of the tilt aftereffect was investigated in normal humans with good stereopsis and in subjects without stereoscopic vision. These latter subjects were divided into two groups: those with and those without a history of strabismus. Strabismic subjects showed grossly reduced interocular transfer of the effect (12% mean transfer). Nonstrabismic subjects had moderate transfer (49%) and normal subjects showed approximately 70% mean transfer. All normal subjects showed greater transfer from the dominant eye to the nondominant than vice versa.

The results are discussed with respect to developmental effects in the visual system of cats and humans, and the nature of the tilt aftereffect.
The Invariance Hypothesis and the Intuitive Perceiver: A Developmental Study
Authors: Kaess D W
Published: January 2007

The influence of the range of angle variation in shape-constancy perception has been studied. Six- to nineteen-year-olds were presented rectangles in three sets differing in the range of angles to which the rectangles were rotated. Contrary to predictions based upon the invariance hypothesis, shape-constancy performance became more veridical, and response consistency increased, as the angles to which the forms were rotated were made more similar to each other. Consequently, it was concluded that observers at all ages studied used the intuitive mode of perceptual operation in the shape-constancy task.
Kinaesthetic Spatial Aftereffects from One and Two Wrists: A Further Investigation
Authors: Frisby J P , Empson Janet M
Published: January 2007

An experiment is described which investigated a kinaesthetic spatial aftereffect related to the wrist joint. A group of 24 subjects were required to point to ‘straightahead’ using first one wrist and then the other. This ‘two-handed successive settings’ procedure yielded a significant kinaesthetic spatial aftereffect of 4·69° per wrist ( p < 0·001), a value very similar to that found by Empson and Frisby (1972) for ‘two-handed simultaneous settings’ (4·66° per wrist). The theoretical implications of this similarity are discussed in relation to the different demands made upon the subject during one- and two-handed pointing tasks.
Analysis of a Stroboscopic Illusion of Motion
Authors: Albert R , Donderi D
Published: January 2007

A visual illusion reported by D. M. MacKay occurs when a steady light is viewed against a surrounding intermittently-illuminated circle. The light appears to jump out of the circle when (1) saccadic eye movements are made to or from the stationary light and circle, and (2) when a subject visually tracks the moving light and circle. We measured the frequency of the illusion under condition (1), and under modified versions of condition (2) in which the circle was replaced by a vertical line to one side of the light or by two vertical lines at the same distance from the light on opposite sides. The effects of varying eye movement distances and rates of intermittent illumination on the frequency of the illusion are investigated. The normal deviate corresponding to the probability of occurrence of the illusion on a single illumination flash is found to be linearly related to ln( x/r), where x is the distance the light moves between flashes, and r is the radius of the background circle or the perpendicular distance of the line to the light. The illusion occurs because the changing position of the circle or line is not predicted during the interval between flashes, and the position of the light is perceived relative to the previous location of the circle or line.
Comments on Assimilation Theory and the Reversed Müller—Lyer Illusion
Authors: Fellows B J
Published: January 2007

This paper is a comment on the preceding paper in this issue by Pressey and Bross. The author reviews his position on the reversed Müller–Lyer illusion in which the illusion is explained in terms of the ‘enclosing nature’ of the ingoing fins. The two difficulties with this explanation pointed out by Pressey and Bross are discussed. Recent experimental work on the effects of enclosures is reported. A critique of Pressey and Bross's explanation of the reversed Müller–Lyer illusion is presented.
Apparent Depth and the Müller—Lyer Illusion
Authors: Georgeson M A , Blakemore C
Published: January 2007

The Müller–Lyer illusion was presented stereoscopically as either a flat or a three-dimensional figure. When the flat figure was made to appear closer or further than a comparison line, the illusion persisted along with large changes in overall size due to classical size constancy. When the fins of the figure were tilted in depth the illusion was somewhat reduced for both forward and backward tilts. It is argued that the size-constancy theory of illusions should predict an enhancement when stereopsis and the typical perspective view' reinforce each other, and abolition or reversal of the illusion when they are in opposition. These results therefore pose some problems for the theory.
The Locus of Adaptation to Auditory—Visual Conflict
Authors: Radeau Monique
Published: January 2007

The site of adaptation resulting from exposure to spatially discordant visual and auditory cues was determined by comparing, for both sensory modalities, shifts in pointings with shifts in estimations of ‘straight ahead’. The exposure task consisted of monitoring a synchronous series of flashes and noises separated 15° laterally by prisms. The shifts it produced for both modalities were of nearly equal magnitude in the two tests.

The results suggest that auditory–visual conflict is resolved through recalibrations at the level of sound–head and of eye–head articulations.
Tactile Pattern Recognition and Body Loci
Authors: Scadden L A
Published: January 2007

Experimentation was conducted to compare tactile pattern recognition on three body loci—back, abdomen, and inner thigh. Five blind subjects, experienced users of a tactile vision substitution system which displays images picked up by a television camera through patterns of vibratory stimulation on the skin, were asked to identify letter images displayed on three body regions. Though the previous experience had been limited to stimulation on the back, recognition accuracy and latency were significantly better on the abdomen. The results indicate that immediate transfer of previous learning occurs when body locus of stimulation is shifted, and further suggest that neural networks for tactile pattern recognition do not include specific peripheral neural receptors.
Hearing with the Hands
Authors: Anstis S M
Published: January 2007

A subject wore for six days a microphone on each hand, connected to stereo headphones. This effectively placed his ears on his hands. Hand movements, with eyes closed, produced apparent movements of sound sources, and crossing the hands over appeared to reverse the sound field. No perceptual adaptation to this auditory rearrangement was found.
An Investigation of Dynamic and Static Visual Acuity
Authors: Fergenson P E , Suzansky J W
Published: January 2007

The effect on dynamic visual acuity (DVA) of target angular velocity ω and target exposure time te was examined. The correlation between DVA and static visual acuity (SVA), the ability to discriminate small spatial separations in a stationary target, was also determined.

DVA was measured for pairings of four values of ω (25, 30, 40, and 45 deg s−1) with four values of te (0·4, 0·6, 0·8, and 1·0 s). The twenty-four subjects viewed Landolt-ring targets that were presented as slide projections on a rear-projection screen. The average thresholds for each condition were determined and compared. SVA was measured and correlated with the DVA scores for each condition.

The results indicated that: (i) DVA deteriorated for increased ω or decreased t, with the latter having the most significant effect, (ii) DVA and SVA were not significantly correlated, (iii) the experimental apparatus and procedure were highly reliable, and (iv) DVA improvement with testing was significant for some conditions.
Investigation of Temporal Integration by Video Sampling
Authors: Williams R
Published: January 2007

The results from the preliminary set of experiments in which a new video sampling apparatus was used are reported. With the aid of this apparatus experiments were carried out to measure the maximum visual temporal integration time (critical duration) at various background intensities (0·034–34 cd m−2). The aim was to determine to what extent this phenomenon is attributable to either ‘central’ or ‘peripheral’ events. The extended integration period found for the number recognition task is interpreted as evidence of a ‘central’ process; to follow the argument further, an attempt was made to demonstrate information integration using a rotating form in a similar identification–discrimination situation. Monocular, binocular, and dichoptic arrangements were employed, and the amount of dichoptic summation of form information, achieved by both normal and strabismic subjects without stereoscopic depth perception, was used to test two theoretical models of binocular fusion. In addition, stereoscopic depth was generated with uncorrected sampling of the left and right images, which may be due to the action of a ‘fusion hierarchy’. Signal detection theory is suggested as a possible solution to the problem of expectation effects in identification-threshold experiments.