bluuebunny/crossref_metadata_2025 huggingface dataset:
Lone pair versus bonding pair electrons: The mechanism of electronic polarization of water in the presence of positive ions
Authors: Krekeler Christian , Delle Site Luigi
Published: April 2008

It is commonly accepted that the water molecules in the first solvation shell of a positive ion are strongly polarized because of an elongation of the oxygen lone pair orbitals along the ion-oxygen direction and this is commonly considered the dominant effect. Recent experimental and theoretical works have instead suggested that this is not the dominant aspect and that the problem is by far more complicated. Consistent with the picture given above, here we show that, in particular, an equally important role into the polarization process is played by the bonding pair electrons located along the internal oxygen-hydrogen bond. We also provide some arguments which suggest that the main reason of such a behavior is due to the distortion of the molecular orbitals caused by the interaction between non-hydrogen-bonded water molecules in the first solvation shell of the ion.
Physical subspace in a model of the quantized electromagnetic field coupled to an external field with an indefinite metric
Authors: Suzuki Akito
Published: April 2008

We study a model of the quantized electromagnetic field interacting with an external static source ρ in the Feynman (Lorentz) gauge and construct the quantized radiation field Aμ (μ=0,1,2,3) as an operator-valued distribution acting on the Fock space F with an indefinite metric. By using the Gupta subsidiary condition ∂μAμ(x)(+)Ψ=0, one can select the physical subspace Vphys. According to the Gupta–Bleuler formalism, Vphys is a non-negative subspace so that elements of Vphys, called physical states, can be probabilistically interpretable. Indeed, assuming that the external source ρ is infrared regular, i.e., ρ̂∕∣k∣3∕2∊L2(R3), we can characterize the physical subspace Vphys and show that Vphys is non-negative. In addition, we find that the Hamiltonian of the model is reduced to the Hamiltonian of the transverse photons with the Coulomb interaction. We, however, prove that the physical subspace is trivial, i.e., Vphys={0}, if and only if the external source ρ is infrared singular, i.e., ρ̂∕∣k∣3∕2∉L2(R3). We also discuss a representation different from the above representation such that the physical subspace is not trivial under the infrared singular condition.
Initial-boundary value problem for the equation of timelike extremal surfaces in Minkowski space
Authors: Liu Jianli , Zhou Yi
Published: April 2008

This paper investigate the mixed initial-boundary value problem for the equation of timelike extremal surfaces in Minkowski space R1+(1+n) in the first quadrant. Under the assumptions that the initial data are bounded and the boundary data are small, we prove the global existence and uniqueness of the C2 solutions of the initial-boundary value problem for this kind of equation. Based on the existence results on global classical solutions, we also show that, as t tends to infinity, the first order derivatives of the solutions approach C1 traveling wave, under the appropriate conditions on the initial and boundary data. Geometrically, this means the extremal surface approaches a generalized cylinder which is an exact solution.
Flow normal to a short cylinder with hemispherical ends
Authors: Sheard G. J. , Thompson M. C. , Hourigan K.
Published: April 2008

The flow normal to a cylinder with hemispherical ends is computed using a spectral-element/Fourier method. With variation in the ratio of cylinder length to diameter, this body varies smoothly from a sphere to a straight circular cylinder, providing insight into the relationship between body topology and wake dynamics. This letter displays the wake structure for a range of cylinder lengths up to a Reynolds number of 300 and considers the wake alignment and symmetry at length ratios approaching a spherical body. A time-invariant wake consistent with that behind a sphere is found to preferentially align with a symmetry plane bisecting the major axis of short cylinders, whereas the periodic “hairpin” wake aligns with the minor axis; thus the hairpin vortices shed from alternate sides of the cylinder, just as with Kármán vortex shedding from a circular cylinder. The plane of symmetry is found to break via a supercritical transition at a Reynolds number of 350±2.
Direct electrical observation of spin Hall effect in Bi film
Authors: Fan Jiyu , Eom Jonghwa
Published: April 2008

The strong spin-orbit coupling of Bi makes it an ideal candidate for investigation of the spin Hall effect. Here, we provide the report of a direct electronic observation of the spin Hall effect in Bi film. When a current flows in the Bi film, electrons with opposite spin orientations separately accumulate on the top and bottom surfaces due to the spin Hall effect. The accumulated spins are electrically detected by a ferromagnetic film attached to the bottom surface of the Bi film. At a temperature of 3.0K, the observed voltage difference induced by the magnetization reversal is 1.2μV. By using the previously reported calculation based on the semiclassical Boltzmann equation, we find that the spin Hall conductivity multiplied by the spin injection efficiency is 1.98×102(Ωm)−1.
Magnetism and structural ordering on a bcc lattice for highly magnetostrictive Fe–Ga alloys: A coherent potential approximation study
Authors: Khmelevska T. , Khmelevskyi S. , Mohn P.
Published: April 2008

We calculate the electronic structure, magnetic moments, and ordering energies of highly magnetostrictive Fe1−xGax alloys from first-principles in the composition range up to x=0.25. The coherent potential approximation was used to treat effects of chemical disorder. Given an underlying bcc lattice in whole range compositions investigated, the DO3 type of ordering is found to have a lower energy than A2- and B2-type structures. We find that ordering energies strongly depend on the state of magnetic order such that thermal magnetic disorder strongly favors chemical ordering (DO3 and B2). The values of the magnetic moments of Fe on different sublattices of ordered structures are found to have a distinctive dependency on the Ga concentration. By taking into account the results of earlier fully relativistic and full potential calculations of magnetostriction for ordered stoichiometric Fe3Ga compounds and available experimental phenomenology, our results for disordered alloys suggest an eventually more complex origin of the giant magnetostriction in Fe–Ga alloys than it would appear from a simple electronic structure analysis of ordered stoichiometric compounds.
Diffusion of beryllium in Ge and Si–Ge alloys
Authors: Koskelo O. , Pusa P. , Räisänen J. , Köster U. , Riihimäki I.
Published: April 2008

Diffusion of implanted Be7 in Si1−xGex (x=0.20,0.65,1.00) systems has been studied under intrinsic conditions in the temperature range of 460–720°C by the modified radiotracer technique. Arrhenius-type behavior with activation enthalpies of 2.0eV for Ge and 2.5eV for the Si–Ge alloys was noted. Unexpectedly, the diffusivity of beryllium is higher in the Si0.80Ge0.20 material than in Si0.35Ge0.65 which is discussed in terms of possible prevailing diffusion mechanisms. It is proposed that Be diffusion in Si1−xGex systems is dissociative mechanism dominated for germanium rich materials and the kick-out (or interstitialcy) mechanism dominates in silicon rich materials.
Solder joints fabricated by explosively reacting nanolayers
Authors: Tong M. S. , Sturgess D. , Tu K. N. , Yang J. M.
Published: April 2008

The intense bursts of heat released by explosively reacting multilayer foils can be controlled and used as heat sources in joining technologies. We use this method to produce Si/solder/Si joints to characterize the microstructure of the multilayer foil in the reacted state as well as the foil/solder interface. The resulting structure at the foil/solder interface is a nearly phase-separated, interlocking structure. The joint is tested using single lap shear Cu samples. Fracture surfaces have been analyzed and failure was observed to entirely occur within the solder layer.
Recovery of elastic constant of ultrathin Cu films by low temperature annealing
Authors: Nakamura N. , Ogi H. , Shagawa T. , Hirao M.
Published: April 2008

Annealing effect on the elastic constant of Cu thin films was investigated by acoustic-phonon resonance spectroscopy. Annealing treatment was performed after the deposition in vacuum condition for 30min at various temperatures up to 200°C. It did not cause obvious changes in the x-ray diffraction spectra, but it significantly increased the elastic constant. The elastic constant of the as-deposited Cu film was smaller than that of bulk Cu by 20%, and it recovered to the bulk value by the postannealing at 200°C.
Significance of intracellular and secreted acid phosphatase enzyme activities, and zinc and calcium interactions, on phosphorus efficiency in wheat, sunflower, chickpea, and lentil cultivars
Authors: Gunes Aydin , Inal Ali
Published: April 2008

Phosphorus efficiency (PE), and its relationship with intracellular (APase) and secreted (S-APase) acid phosphatases, anthocyanin accumulation, and calcium and zinc nutrition, were compared among 8 cultivars of each of wheat, sunflower, chickpea, and lentil grown under greenhouse conditions with low and high rates of P supply in a P-deficient calcareous soil. Except for the chickpea cultivars, deficiency of P resulted in significant decreases in shoot dry weight of all the crop cultivars and led to significant decreases in root dry weight in wheat and sunflower, significant increases in root dry weight in chickpea, and no significant difference in root dry weight in lentil. PE differed greatly among species and their cultivars. On average, shoot P concentration in cultivars of wheat, sunflower, chickpea, and lentil increased by 44%, 54%, 47%, and 8%, respectively, with P supply, and the increases in P concentration differed greatly among cultivars of all species. Intracellular leaf APase activity of wheat and lentil cultivars was slightly decreased by P supply, while it was unchanged in sunflower and chickpea cultivars. However, root-secreted acid phosphatase (S-APase) activity was significantly reduced by P supply in wheat, sunflower, and chickpea cultivars. Under low-P conditions, S-APase activities of all species except sunflower were negatively correlated with PE. Phosphorus deficiency increased the anthocyanin concentration of the cultivars of wheat and sunflower, whereas it was usually decreased in cultivars of the P-efficient species chickpea and lentil. In general, concentration of Ca was found to be lower, but Zn concentration was higher, in P-efficient cultivars than in P-inefficient cultivars. The results demonstrated that PE of the cultivars clearly depends on their ability to take up P and Zn, and on secretion of acid phosphatases from their roots under P deficiency. The results also suggest that characteristics of Zn and Ca nutrition should be taken into consideration when screening cultivars of crop species for their P efficiency.
Effect of nutrition from mid to late pregnancy on the performance of twin- and triplet-bearing ewes and their lambs
Authors: Corner R. A. , Kenyon P. R. , Stafford K. J. , West D. M. , Lopez-Villalobos N. , Morris S. T. , Oliver M. H.
Published: April 2008

This experiment was conducted to determine the effect of two different feeding levels on ewes during mid and late pregnancy on lamb birthweight and growth to weaning. Twin- and triplet-bearing Romney ewes (n = 80 and 56, respectively) were allocated to one of two feeding regimes and provided pastures with an average sward height of less than 2 cm (~700 kg dry matter/ha) or greater than 4 cm (~1300 kg dry matter/ha). Ewes were allocated to these feeding regimes during mid pregnancy (day 70–107 of pregnancy; P70–P107) and were reallocated in late pregnancy (P108–P147). This resulted in four sward height treatments: 2–2, 2–4, 4–2 and 4–4. During mid pregnancy, ewes provided with >4-cm-high swards had liveweight gains of 262–290 g/day compared with 12–31 g/day for ewes provided with <2-cm-high swards. In late pregnancy, ewe liveweight gains were influenced by the ewes’ previous nutritional treatment. Ewes in the 2–4 treatment had higher daily gains (538 g/day) than 4–4 ewes (343 g/day). In addition, 4–2 ewes gained 90 g/day compared with 247 g/day for 2–2 ewes. Throughout pregnancy, triplet-bearing ewes were heavier (P < 0.05) than twin-bearing ewes, but during lactation ewe weights were similar. On P130, ewes provided with <2-cm-high swards (4–2 and 2–2) had greater β-hydroxybutyrate (P < 0.05) and lower glucose (P < 0.05) plasma concentrations than ewes provided with >4-cm-high swards (2–4 and 4–4). On P139, however, ewes provided with 4–4 swards had higher plasma non-esterified fatty acid and β-hydroxybutyrate concentrations than ewes in all other treatments. Lambs born to ewes in the 4–4 treatment had the greatest birthweights (P < 0.05), whereas lambs born to 2–2 ewes had the lowest birthweights. The birthweight of lambs born to 2–4 ewes was similar to that of lambs born to ewes provided with 4–2 and 4–4 swards. At weaning, ewe weights were similar between ewe nutritional treatments and ewes bearing twin or triplet fetuses. These findings suggest that when pasture growth is inadequate to provide pasture sward heights of 4 cm throughout pregnancy, restricted intake in mid-pregnancy may be partially compensated by providing additional pasture in late pregnancy.
Relocation does not have a significant effect on the growth rate of Bos indicus cross steers
Authors: Holroyd R. G. , Doogan V. J. , Jeffery M. R. , Lindsay J. A. , Venus B. K. , Bortolussi G.
Published: April 2008

This experiment tested the hypothesis that relocating cattle is detrimental to their growth. The study examined the effect of having relocated cattle mixed with, or segregated from, the local acclimatised cattle at the destination property. Bos indicus cross steers (120) were allocated to three groups and were relocated, in two separate cohorts, 980 km from northern Queensland to improved pastures in central Queensland. At the start of Phase 1, the control group (C) was moved 3 months before the other two groups. The remaining two groups grazed native pastures; one group was supplemented (SR) to increase growth rate similar to that expected from improved pasture in central Queensland and the other was not supplemented (R). At the end of Phase 1, C was significantly (P < 0.05) heavier than SR, which was significantly (P < 0.05) heavier than R. At the start of Phase 2, the SR and R groups were relocated and after transportation the R and SR groups lost 12 kg or 4.4% of liveweight and 18 kg or 5.7% of liveweight, respectively; this weight loss was recovered after 5 days. All steers were reallocated to segregated (SEG) or mixed (MIX) treatment groups forming six treatments (SEG.C, SEG.R and SEG.SR and MIX.C, MIX.R and MIX.SR). There were no significant differences in liveweights within the SEG treatments by 57 days or within the MIX treatments by 106 days after relocation. There were few if any significant differences in the plasma constituents and differential leucocyte counts of the steers and most results were within physiologically normal ranges. We conclude on the basis of these results and of other experiments that the anecdotal poor performance of cattle after relocation appears to be unfounded.
The Effect of Knowledge of Results on Learning and Performance IV. The Direction of the Error in Very Simple Skills
Authors: Dees Valerie , Grindley G. C.
Published: April 2008

Re-examination of the data discussed in previous papers of this series shows a greater tendency toward “overshooting” when the time interval between trials, in some of the experiments, is short than when it is longer. The subject tends to make a bigger movement or exert more pressure with short intervals. This seems to be true with or without visual knowledge of results. On the other hand, with the experiments in which the task was to press a key for a given short interval, the effect was not conclusively shown.

A hypothesis is put forward to explain these results in terms of proprioceptive adaptation.
A Preliminary Report on a New Auditory After-Effect
Authors: Deutsch J. A.
Published: April 2008

It is found that protracted monotic stimulation at a certain frequency lowers the DL of that frequency for the contralateral ear by some 47 per cent. There were eight subjects and six controls; the frequency was 1,000 c.p.s. at 40 d.b.s. It is suggested that this after-effect is analogous to figural after-effects in vision. (Some further related findings, as yet preliminary, are also reported).
Transfer of Training and Skill Assumptions in Tracking Tasks
Authors: Gibbs C. B.
Published: April 2008

Matched groups of subjects were used to test the learning and transfer effects that follow changes in the display, the muscular reactions and the directional relationship between stimulus and response in a tracking task. Two arrangements were compared in the relationship studies: one arrangement of the stimuli and reactions was similar, and the other was opposed to that used in many every-day skills. The familiar arrangement was easier to learn. There was high positive transfer from the unfamiliar to the familiar, and little transfer from the familiar to the unfamiliar.

The physical dimensions of the display were varied to give two tasks with different stimuli. The initial learning times were equal for both tasks, and the transfer between them was high, positive, and equal. Two further tasks varied in the extent, speed and force of the required muscular movements. One task proved more difficult to learn initially, and there was greater transfer from the difficult to the easy task than from the easy to the difficult. A further experiment tested the effects of changing the difficulty of a tracking course, and it was found that learning was more rapid on the more difficult course. A difference in difficulty between two tasks, therefore, determined both the amount of transfer between them and the rate of learning the tasks.

New measures were developed to test the transfer between tasks of unequal content, and the effect of such inequalities upon the rate of learning. The findings are discussed, as are their possible implications for transfer measurement and their bearing upon existing theories of transfer.
The Operation of an Acquired Drive in Satiated Rats
Authors: Danziger K.
Published: April 2008

A series of four short experiments indicates that the behaviour of satiated rats in a runway, at the end of which they have previously been rewarded, differs significantly from the behaviour of satiated rats without previous reward in the experimental situation. The former group reach the end box more quickly after having been put in the starting box of the runway and if provided with food in the end box proceed to eat it, although they have just refused similar pieces of food in their home cages. This is shown not to be due to defective satiation or the operation of fear in the control group. When runs and feeding in the end box are separated during the training period, the previously rewarded group still shows a more vigorous response on satiated trials, indicating that it is a reward expectancy about the goal box rather than a running habit which has become “functionally autonomous”, acting as a situation-specific drive.
The Perception of a Changing Shape
Authors: Langdon J.
Published: April 2008

Under specified conditions a pair of simple shapes are matched by a subject when almost all supplementary textural and space cues of depth vision have been removed. Under such conditions it is found that shape constancy is no longer present. However, the effect of regular rotatory motion of the shape is sufficient to restore constancy in the continued absence of other cues. Degree of perceptual constancy appears to be correlated with rate of change of shape. It is suggested that an explanation of the phenomenon is to be sought along the lines of Michotte's concept of “object creation” rather than in terms of gradient variables.
Learning of a Serial Task by Different Age Groups
Authors: Kay H.
Published: April 2008

In a serial learning task given to subjects whose ages ranged from twenty to seventy, a decline in performance showed itself as a loss of speed in the thirties, a loss of accuracy in the forties, and a marked loss of both speed and accuracy in the fifties and sixties. Experiments on recall and reorganization of material verified that older subjects were forgetting more quickly than younger, but that one of their main difficulties was an inability to substitute new reponses in an already mentally formed sequence.

Older subjects were not introducing new learning features but accentuating normal tendencies, such as the repetition of the same error at the same serial position. In so far as subjects learned their repeated errors, final learning involved unlearning, with the often observable phenomenon of the previously learned error serving as the cue for the more recently learned correct response. In terms of schematic concepts of mental functions, serial learning difficulty was not so much the formation of a general “scheme” but its subsequent amendment. Preformed habits influenced both the learning procedure and its results, particularly in the constraints and expectancies which the making of one serial response had upon another.
An Experiment in Problem Solving
Authors: Whitfield J. W.
Published: April 2008

Trial-and-error problems are described in terms of “stimulus” difficulty, which is a measure of the number of possible modes of response left to the individual when all the information given is taken into account; and “phenomenal” difficulty, which is a measure derived from the individual's performance. An experiment is described in which three types of problem were presented to human subjects. In all three problems the stimulus difficulty was calculable, stage by stage, in the solution. The problems differed in this stimulus difficulty and also in the qualitative nature of the information provided—from unequivocal to conditional. It is shown that the qualitative difference of the nature of the information bears most relationship to phenomenal difficulty. Some observations are made on the modes of solution adopted, and further experimental work is suggested.
The Limits of the “Psychological Refractory Period”
Authors: Davis R.
Published: April 2008

Previous evidence on the psychological refractory period is shown to be inadequate on the crucial issue of whether delays, which cannot be overcome by practice, occur in responding to the second of two signals, when the interval between them is less than 0·5 seconds. For simple key pressing responses it is shown that when the interval between signals is less than the reaction time to the first signal, delays in the reaction time to the second signal occur in a predictable manner. When the interval is greater than the first reaction time, however, no such delays are found. Possible reasons for the discrepancy between these and earlier findings are suggested.
A Note on Immediate Memory
Authors: Zangwill O. L.
Published: April 2008

In the course of an extensive inquiry into verbal memory processes (Gomulicki, 1952), some data were collected which appear to throw fresh light on the nature of immediate memory. In particular, it was found that many of the varieties of constructive change defined by Bartlett (1932) in connexion with long-term recall could be traced in the immediate reproduction of passages so brief as barely to exceed the memory-span. As changes of this nature do not appear to have been previously described in connexion with short-term recall some illustrative extracts from our material will be given. A full analysis along somewhat different lines has been presented elsewhere (Gomulicki, 1952).

In Gomulicki's experiments, narratives varying in length between 15 and 200 words were read aloud to 50 subjects, who were required to reproduce each passage orally as accurately as possible immediately after it had been read. The subjects (of whom half were women) were University graduates and undergraduates aged between 20 and 30. All subjects were tested individually and their reproductions recorded verbatim. In the present note, we shall be concerned only with the results given in the case of two passages, respectively 22 and 44 words in length. Despite their brevity, striking and consistent changes were observed in the reproductions which merit brief analysis.
Successive Responses to Simultaneous Stimuli
Authors: Broadbent D. E.
Published: April 2008

Previous work had shown that, when a memory-span experiment is performed with half the items presented to one ear, and half simultaneously to the other, a certain order of response appears. Either one ear or the other is dealt with first, and then the remaining items produce a response afterwards. The present results extend this finding to the eye and the ear rather than the two ears, and also to two voices distinguished by their frequency characteristics. For the latter condition, it is also shown that alternation of attention can take place at a speed faster than between the two ears. The effect thus appears to be a general one, and not merely a peculiarity of binaural hearing.
Binocular Vision with two Stabilized Retinal Images
Authors: Ditchburn R. W. , Pritchard R. M.
Published: April 2008

Experiments are described in which each eye is presented with a target whose image remains on the same part of the retina when the eye moves. The patterns presented to each eye may be similar and may be placed on corresponding parts of the retina or may be placed in non-corresponding positions: alternatively, different targets may be presented to the two eyes. Each pattern fades intermittently. Sometimes both are seen together and sometimes both fields are dark at once. There is a small negative correlation between the times of clear vision with the two eyes. When corresponding areas of the two retinas are illuminated with red and green light respectively, the composite colour (yellow) is never perceived with steady illumination. When two similar patterns are in nearly corresponding positions there may be subjective fusion. With two different targets there is sometimes a subjective impression that the two patterns move with respect to one another even though their positions on the retina are fixed.
Discrimination Learning Theory: Excitatory vs. Inhibitory Tendencies in Monkeys
Authors: Ettlinger George
Published: April 2008

Two methods of testing between excitatory and inhibitory tendencies in simultaneous two-choice discrimination learning by monkeys are proposed. The use of both methods yields results favouring an excitatory as opposed to an inhibitory mechanism as the unitary process in discrimination learning.
Grouping of Stimuli and Apparent Exceptions to the Psychological Refractory Period
Authors: Halliday A. M. , Kerr M. , Elithorn A.
Published: April 2008

When a subject is called upon to respond independently to two stimuli, the second of the two responses is often delayed if the stimuli follow closely on one another, and this has led to the suggestion that in making decisions the human operator accepts and organizes the available input information intermittently in the manner of a discontinuous servo. According to this view two nearly simultaneous stimuli can only be dealt with equally fast if they are grouped into a single decision to respond to both stimuli; otherwise one will have to wait for the attention of the central mechanism until the other has been dealt with. In the present experiment it is shown that delays in the second response are not necessary or invariable, and that the pattern and timing of the second responses when they are performed without delay differ in important respects from those to be expected of grouped responses. It is concluded that the central mechanisms concerned in the response do not possess the limitations that the single channel theory would suggest.
Studies in Olfactory Acuity. I: Measurement of Olfactory Thresholds in the Rat
Authors: Eayrs J. T. , Moulton D. G.
Published: April 2008

The capacity of the rat to respond to olfactory cues has been studied in three experimental situations: (i) an elevated Y-maze, (ii) a rectangular choice apparatus in which extraneous environmental cues were present, and (iii) a circular choice apparatus from which such cues were either excluded or randomized.

No rat showed any sign of learning on the Y-maze even after extensive training and the application of electric shock as deterrent for error.

Some rats succeeded in performing an olfactory discrimination in the rectangular choice apparatus but learning was retarded, and in some cases inhibited, by the counter-influence of non-olfactory factors.

All rats readily learned an identical discrimination when shielded from such cues in the circular choice apparatus which provides a satisfactory medium both for training and for the study of olfactory acuity.

Differences in the behaviour of rats on these three types of apparatus suggest first, that the formation of learned habits based on olfaction depends on the close contiguity of stimulus and reward, and second that the sense of smell possesses weak orientating properties by comparison with those exerted by other modalities. The findings thus help to explain differences in the ease or difficulty uith which olfactory discriminations have been established by earlier workers.
Shorter Articles and Notes two more Visual Theorems
Authors: Brindley G. S.
Published: April 2008

The basis of the widely held opinion that the spectral sensitivities of the mechanisms determining trichromacy must be linearly related to the spectral mixture functions is examined, and a proof from simple assumptions is stated.

It is proved also that, on the van der Velden hypothesis of independent sensitive units, a spatial or temporal summation law of the form AIn = c implies a frequency-of-seeing curve of the form Q = I— e−KIn ( Q = probability of detecting a stimulus of size A and intensity I; n, c and K are constants).
The Effect of Temporal Separation and Prior Habituation upon Preconditioning
Authors: Howarth Edgar
Published: April 2008

The effect of temporal separation and prior habituation was tested by measuring response transfer in a shuttle box following different initial treatments. Thirty hooded rats were split into three main groups and six sub-groups. One main group was preconditioned with concurrent light and sound stimuli, another with temporally spaced stimuli, and a control group had no preconditioning. Half of each main group was permitted to explore the apparatus before preconditioning on the supposition that this might reduce emotionality and hence reduce startle or attention responses.

It was found that concurrent stimulation produced significantly greater response transfer than in controls, whereas preconditioning with spaced stimuli did not. Prior habituation produced no significant effect on the amount of response transfer.
Perception of Sequence in Auditory Events
Authors: Ladefoged Peter , Broadbent Donald E.
Published: April 2008

A series of tape-recorded sentences were presented to various groups of listeners, totalling 164. During each sentence an extraneous sound was present on the recording, and the listener had to indicate the exact point in the sentence at which this sound occurred. It was found that errors were made which were large compared with the duration of a single speech sound; which suggests that the listener does not deal with each sound separately but rather with a group of sounds. Errors were reduced if the sentence consisted of a series of digits rather than an ordinary text, or if the listeners were trained in phonetics. Prior knowledge of the content of the sentence did not affect accuracy. The direction of error was usually to refer the extra sound to an early point, but it is affected by the relative position of the extra sound in the sentence. These results can be regarded as an extension, to the case where all stimuli are presented to the same sense, of classic results on prior entry.
Shorter Articles and Notes Grouping Strategies with Simultaneous Stimuli
Authors: Gray J. A. , Wedderburn A. A. I.
Published: April 2008

Broadbent (1956) reports that two lists of digits, each presented to one ear separately so that the items in the two series coincide in time, are grouped together according to the ear-of-arrival, and that these two lists are accordingly recalled separately, one after the other. To ascertain whether such a tendency reflected some built-in mechanism or whether it was due to an optional tactic, adopted through success in making sense of message sequences in other situations, an experiment was designed in which a meaningful message would emerge for the subject if the ear-of-arrival cue was ignored. In this experiment, words broken up into syllables, and phrases broken up into their monosyllabic constituent words were presented to the subject, with the constituents alternating between the two ears. At the same time lists of digits were presented to whichever ear was unoccupied. The results show that recall by meaning rather than by ear-of-arrival, when these are in conflict, can occur and is no less efficient.
Combination of Drive and Incentive
Authors: Hulicka Irene Mackintosh
Published: April 2008

This experiment was designed to investigate the combination of drive and incentive as determinants of performance. Nine groups of rats were trained to press a bar under three levels of food deprivation (12, 24 and 36 hr.) and three incentive conditions (1, 2 and 3 pellets). Response strength was estimated by counting the number of responses with a latency of 1 sec. or less during five 20 trial sessions. The results indicated that response strength increased with hours of deprivation and with amount of food reward. Significant interactions between sessions and drive, and sessions and incentive provided additional support for the multiplicative combination of H (habit) and D (drive) and H and K (incentive). The lack of significant interaction between D and K was interpreted as supporting the hypothesis that D and K combine additively rather than multiplicatively.
Apparent Movement and the Brown-Voth Experiment
Authors: Sylvester John
Published: April 2008

An experiment on apparent movement reported by Brown and Voth and referred to by Osgood and Bartley was repeated. The results obtained differed from those reported by Brown and Voth, but exhibited phenomena not described by them. Further experiments derived from their theories were also carried out, the results failing to support Korte's laws and raising some new points.
The eIF4E RNA regulon promotes the Akt signaling pathway
Authors: Culjkovic Biljana , Tan Keith , Orolicki Slobodanka , Amri Abdellatif , Meloche Sylvain , Borden Katherine L.B.
Published: April 2008

Eukaryotic initiation factor 4E (eIF4E) promotes cellular proliferation and can rescue cells from apoptotic stimuli such as serum starvation. However, the mechanisms underlying apoptotic rescue are not well understood. In this study, we demonstrate that eIF4E overexpression leads to enhanced survival signaling through Akt and that eIF4E requires Akt1 to rescue serum-deprived fibroblasts. Furthermore, a mutant form of eIF4E (W73A), which is messenger RNA (mRNA) export competent but does not promote translation, rescues cells as readily as wild-type eIF4E. We show that eIF4E mediates Akt activation via up-regulation of Nijmegen breakage syndrome 1 (NBS1), a phosphoinositide-3 kinase–Akt pathway upstream activator. Additionally, eIF4E coordinately up-regulates the expression of downstream effectors of the Akt pathway, thereby amplifying Akt signaling effects. A negative regulator of eIF4E, the promyelocytic leukemia protein (PML), suppresses Akt activation and apoptotic rescue. These PML activities likely arise, at least in part, through its inhibition of eIF4E-mediated NBS1 mRNA export. In summary, eIF4E coordinately regulates gene expression to potentiate Akt activation, an activity required for apoptotic rescue.
Compensatory role for Pyk2 during angiogenesis in adult mice lacking endothelial cell FAK
Authors: Weis Sara M. , Lim Ssang-Taek , Lutu-Fuga Kimberly M. , Barnes Leo A. , Chen Xiao Lei , Göthert Joachim R. , Shen Tang-Long , Guan Jun-Lin , Schlaepfer David D. , Cheresh David A.
Published: April 2008

Focal adhesion kinase (FAK) plays a critical role during vascular development because knockout of FAK in endothelial cells (ECs) is embryonic lethal. Surprisingly, tamoxifen-inducible conditional knockout of FAK in adult blood vessels (inducible EC–specific FAK knockout [i-EC-FAK-KO]) produces no vascular phenotype, and these animals are capable of developing a robust growth factor–induced angiogenic response. Although angiogenesis in wild-type mice is suppressed by pharmacological inhibition of FAK, i-EC-FAK-KO mice are refractory to this treatment, which suggests that adult i-EC-FAK-KO mice develop a compensatory mechanism to bypass the requirement for FAK. Indeed, expression of the FAK-related proline-rich tyrosine kinase 2 (Pyk2) is elevated and phosphorylated in i-EC-FAK-KO blood vessels. In cultured ECs, FAK knockdown leads to increased Pyk2 expression and, surprisingly, FAK kinase inhibition leads to increased Pyk2 phosphorylation. Pyk2 can functionally compensate for the loss of FAK because knockdown or pharmacological inhibition of Pyk2 disrupts angiogenesis in i-EC-FAK-KO mice. These studies reveal the adaptive capacity of ECs to switch to Pyk2-dependent signaling after deletion or kinase inhibition of FAK.
‘International Criminalisation and Child Welfare Protection’: the Optional Protocol to the Convention on the Rights of the Child
Authors: Buck Trevor
Published: April 2008

The Optional Protocol to the Convention on the Rights of the Child (CRC) on the Sale of Children, Child Prostitution and Child Pornography has two overall aims: (i) to strengthen international criminalisation and (ii) to provide welfare protection for child victims. This article reviews the context of the Protocol including the work of the Special Rapporteur. It examines reservations and declarations made by states upon ratification and provides a preliminary analysis of country reports to the Committee on the Rights of the Child. It concludes that while the Protocol may have assisted in the process of international criminalisation, its implementation appears to have had a weaker impact on the protection of child victims.
Extreme Forms of Child Labour in Turkey
Authors: Degirmencioglu Serdar M. , Acar Hakan , Acar Yüksel Baykara
Published: April 2008

Two little known forms of child labour in Turkey are examined. The process through which these children are made to work has parallels with the experiences of slaves. First, a long‐standing practice from Northwestern Turkey of parents hiring children to better‐off farmers is examined. Further, a more recent problem is examined where children are trafficked to big cities and forced to join criminal rings. Both forms of child labour are consequences of poverty. The factors that give rise to child trafficking and parents letting their children be trafficked are extreme poverty and internal displacement of families.
p38 mitogen‐activated protein kinase inhibitor LY2228820 enhances bortezomib‐induced cytotoxicity and inhibits osteoclastogenesis in multiple myeloma; therapeutic implications
Authors: Ishitsuka Kenji , Hideshima Teru , Neri Paola , Vallet Sonia , Shiraishi Norihiko , Okawa Yutaka , Shen Zhenxin , Raje Noopur , Kiziltepe Tanyel , Ocio Enrique M. , Chauhan Dharminder , Tassone Pierfrancesco , Munshi Nikhil , Campbell Robert M. , Dios Alfonso De , Shih Chuan , Starling James J. , Tamura Kazuo , Anderson Kenneth C.
Published: April 2008

The interaction between multiple myeloma (MM) cells and the bone marrow (BM) microenvironment induces proliferation and survival of MM cells, as well as osteoclastogenesis. This study investigated the therapeutic potential of novel p38 mitogen‐activated protein kinase (p38MAPK) inhibitor LY2228820 (LY) in MM. Although cytotoxicity against MM cell lines was modest, LY significantly enhanced the toxicity of bortezomib by down‐regulating bortezomib‐induced heat shock protein 27 phosphorylation. LY inhibited interleukin‐6 secretion from long term cultured‐BM stromal cells and BM mononuclear cells (BMMNCs) derived from MM patients in remission. LY also inhibited macrophage inflammatory protein‐1α secretion from patient MM cells and BMMNCs as well as normal CD14 positive osteoclast precursor cells. Moreover, LY significantly inhibitedin vitroosteoclastogenesis from CD14 positive cells induced by macrophage‐colony stimulating factor and soluble receptor activator of nuclear factor‐κB ligand. Finally, LY also inhibitedin vivoosteoclatogenesis in a severe combined immunodeficiency mouse model of human MM. These results suggest that LY represents a promising novel targeted approach to improve MM patient outcome both by enhancing the effect of bortezomib and by reducing osteoskeletal events.
Importance of murine Vδ1+γδ T cells expressing interferon‐γ and interleukin‐17A in innate protection against Listeria monocytogenes infection
Authors: Hamada Satoru , Umemura Masayuki , Shiono Takeru , Hara Hiromitsu , Kishihara Kenji , Tanaka Kensho , Mayuzumi Hirokazu , Ohta Takao , Matsuzaki Goro
Published: April 2008

Murine γδ T cells participate in the innate immune response against infection by an intracellular pathogen Listeria monocytogenes. Vδ1+γδ T cells coexpressing Vγ6 are a major γδ T‐cell subpopulation induced at an early stage of L. monocytogenes infection in the livers of infected mice. To investigate the protective role of the Vγ6/Vδ1+γδ T cells against L. monocytogenes infection, Vδ1 gene‐deficient (Vδ1−/−) mice were analysed because these mice selectively lacked a Vγ6/Vδ1+γδ T‐cell subpopulation in the L. monocytogenes‐infected liver. The Vδ1−/− mice showed increased bacterial burden in the liver and spleen, and decreased survival rate at an early stage of L. monocytogenes infection when compared to wild‐type mice. Histological examination showed abscess‐like lesions and unorganized distribution of macrophages in the liver of the Vδ1−/− mice but not in the wild‐type mice after L. monocytogenes infection. The Vγ6/Vδ1+γδ T cells produced interferon‐γ and interleukin‐17A. All the results suggest that murine Vγ6/Vδ1+γδ T cells control the innate protective response against L. monocytogenes infection through production of the proinflammatory cytokines interferon‐γ and interleukin‐17A in the infected liver.
Cloning and molecular characterization of two invertebrate‐type lysozymes from Anopheles gambiae
Authors: Paskewitz S. M. , Li B. , Kajla M. K.
Published: April 2008

We sequenced and characterized two novel invertebrate‐type lysozymes from the mosquito Anopheles gambiae. Alignment and phylogenetic analysis of these and a number of related insect proteins identified through bioinformatics strategies showed a high degree of conservation of this protein family throughout the Class Insecta. Expression profiles were examined for the two mosquito genes through semiquantitative and real‐time PCR analysis. Lys i‐1 transcripts were found in adult females in the fat body and Malpighian tubules, whereas Lys i‐2 was detected only in fat bodies. Blood‐feeding resulted in significantly increased transcript abundance for both genes in the midguts. Neither gene was upregulated following bacterial challenge.
Trying times with a turtle*
Authors: Parry M. T.
Published: April 2008

This paper is an edited and much‐abridged diary of the day‐to‐day problems encountered by the author in her attempt to set up a school investigation. This was a controlled experiment involving the use of floor and screen turtles with two groups of fourth year primary school children. Apart from the educational, psychological and administrative problems involved in the implementation of such an experiment, the practical difficulties were many.
Report to the Alvey Directorate on a short survey of expert systems in UK business*
Authors: D'Agapeyeff A. O
Published: April 2008

Simpler expert systems are practical and being implemented now by self‐taught teams, with little risk at relatively low‐cost, to produce modest but unusual gains. It is necessary to correct the impression, much heralded hitherto, that expert systems are inherently complex, risky and demanding. This impression is a handicap to competitive developments in the supply and usage of advanced information technology.
Forms and functions of feedback in CAI and CAL
Authors: Heywood G.
Published: April 2008

Abstract The form and function of reinforcement is discussed with attention to the focus for feedback. The case studies of five junior schools provide data and field notes for a tentative analysis of the determinants of reinforcement including organizational factors and (especially) types of CAI or CAL applications.
Microelectronic control in schools
Authors: Avis P. , Martin D. J.
Published: April 2008

Abstract This paper reviews various approaches to electronic control which are possible in secondary schools. It presents the case for including elements of work on control in CDT courses, in courses on computer studies and computer awareness. Resources for work in schools are reviewed.
Patterns of teenage computer usage
Authors: Fife‐Schaw C. , Breakwell G. M. , Lee T. , Spencer J.
Published: April 2008

Abstract While there has been considerable attention given to gender differences in the use of computers both at school and at home, relatively little has been published about the types of use teenagers make of computers. This paper reports findings about usage from a sample of 1747 14–18 year olds. The data suggest that while games playing is by far the most popular use, it may serve an interest maintenance function that facilitates progression on to more complete use of computer facilities and the learning of programming languages. The implications of these findings for educational practice are discussed.
Local Education Authority policies for computers in education
Authors: Btirdett F. J.
Published: April 2008

Abstract  Local Education Authorities (LEAs) vary in their attitudes to the need for policies on the use of microcomputers in education and yet such policies may be essential to the effective use of microcomputers in the learning process. This paper reports on four case studies that attempt to explain why LEAs have varied in their policy response to the new technology.
Probing a student teacher's cognitive structure of software
Authors: Geyer T.
Published: April 2008

Abstract  ‘Cognitive mapping’ is explored as a way of finding out how a teacher perceives software. Knowledge of the concepts and strategies a teacher identifies and how he or she represents them, can indicate the level of guidance that is required before the software is used in the classroom. Apart from being a possible basis for a teacher's own preparation, it raises some implications for the content of courses in CAL.
Response evaluation in computer based tutorials
Authors: Smyth T.
Published: April 2008

Abstract  This paper describes a program that allows students to undertake nomenclature tutorials in organic chemistry. The user response is evaluated according to a set of rules, based on those (rules) for naming organic compounds systematically, so that appropriate feedback and help can be given to the user at all levels within the problem. The approach to the design and implementation of this rule‐based feature is described and those aspects that are relevant to computer based tutorials in general are discussed.