Interannual variations in condition indices of larval Norwegian spring-spawning herring

The sea water temperature off the Norwegian coast was lower in 1994 than in 1992 and 1993. RNA/DNA ratios of Norwegian spring spawning herring increased with increasing larval dry weight all years, except for larvae sampled south of 62°N in 1994. The RNA/DNA ratios indicated that each year, only a small portion ( 0.7%) of the larvae were starving. RNA/DNA ratios and temperature were negatively correlated in 1992, but in other years no significant correlations were found. Residuals of In RNA v . In DNA and In W v. L _s were poorly correlated in all years, but residuals of In RNA v. In DNA and In DNA v. In W were negatively correlated in all years. Principal component analysis showed that the RNA/DNA ratio and DNA (% of weight) were correlated with different axes. Abundance data for herring at the early larval and 0-group stages in 1992–1994 indicated higher mortality in 1994 compared with the other years. The data do not indicate that average larval condition was poorer in 1994 than in other years. However, the variability in larval condition was higher in 1994 than in other years, and the condition of later larval stages was relatively lower in 1994 than in other years.     

An experimental study on the self-reference effect

Self-reference at encoding increases the probability of recollective experience in recognition memory. Self-reference effect (SRE) in memory is observed when the degree of self-reference of to-be-remembered materials is varied. Usually items encoded in terms of self-reference are associated with significantly higher recall performance relative to items encoded in other ways, including semantic encoding. In our three experiments, four orientating tasks formed four levels in a between-subjects design. The conditions were rating personality traits with reference to self, mother, Lu Xun (a famous Chinese writer) or rating the traits on a negative-positive dimension. In a recognition test, subjects first identified old items and then indicated which of these were accompanied by recollective experience ('remember' responses) and which were recognized on some other basis ('know' responses). Our results showed that both the self-reference condition and mother condition were associated with the same highest propo     

An experimental study on the self-reference effect

Self-reference at encoding increases the probability of recollective experience in recognition memory. Self-reference effect (SRE) in memory is observed when the degree of self-reference of to-be-remembered materials is varied. Usually items encoded in terms of self-reference are associated with significantly higher recall performance relative to items encoded in other ways, including semantic encoding. In our three experiments, four orientating tasks formed four levels in a between-subjects design. The conditions were rating personality traits with reference to self, mother, Lu Xun (a famous Chinese writer) or rating the traits on a negative-positive dimension. In a recognition test, subjects first identified old items and then indicated which of these were accompanied by recollective experience (‘remember’ responses) and which were recognized on some other basis (‘know’ responses). Our results showed that both the self-reference condition and mother condition were associated with the same highest proportion of correct remember responses and the same lowest proportion of correct know responses. In contrast, for Western subjects, the self-reference condition, relative to the mother condition, was associated with a higher proportion of correct remember responses and a lower proportion of correct know responses. We discussed the results with reference to the HERA model (hemispheric encoding/retrieval asymmetry).     

Do African grey parrots (Psittacus erithacus) know what a human experimenter does and does not see?

Perspective-taking is a cognitive ability that can be useful to access information during social interactions. This ability is extensively exploited in humans, and some evidence of it has been found in other mammals and some bird species. Perspective-taking requires individuals to be sensitive to the attentional state of others. In this experiment, three hand-reared grey parrots were tested on their ability to adapt their behaviours according to the perception of a human handler. Two different screens placed on a table separating the human side from the parrot's side were used: one transparent and one opaque. In the Control condition food was put behind each screen, whereas in the Test condition ‘forbidden’ objects (attractive for the bird but normally not accessible) were placed behind each screen. Birds were expected to choose at random between the two screens in the Control condition but to prefer the opaque one in the Test condition in order to avoid being scolded and chased away. In the Control condition, birds chose at random, whereas the older parrot chose the opaque screen significantly more in the Test condition. The latency for the decision was longer in the Test condition compared to Control, and when choosing the Transparent screen compared to the Opaque.     

The role of individual differences and patterns of resolution in the formation of dominance orders in domestic hen triads

This research compares the role of initial individual characteristics to that of patterns of resolution in which successive dominance relationships are established during the formation of triads in the domestic hen. Combining weight and comb size with prior victory or defeat in the site of encounter, we created three levels of asymmetries of characteristics for triads of hens. The effects of these asymmetries were then examined on the resultant hierarchies and on the order of conflict resolution within triads under two different conditions of assembly. In one condition (simultaneous triad), the three hens were simultaneously introduced to each other and could thus freely choose their opponent. In the other condition (step-assembled triad), the hen predicted to occupy the highest rank was left on standby and introduced once the other two hens had settled dominance. This condition disrupts the normal process of hierarchy formation by imposing the first sequence of dominance settlement. We found that the structure of triadic hierarchies can be predicted from individual characteristics existing prior to hierarchy formation. No difference in the resultant structures were found between conditions of introduction, though different paths of conflict resolution were followed indicating that individual differences had a more determining role on the resultant hierarchies than patterns of resolution. In addition to demonstrating that individual differences determine resultant triadic structures, the present results also show that the same end structures can be reached by following resolution paths that are not necessarily of the Double Dominance and Double Subordinance types as prescribed by Chase's model. It is also found that in the simultaneous condition hens select each other to form pairs. Therefore, individuals do not meet at random but choose each other as opponents. The two hens predicted from individual differences to occupy the highest ranks first settle dominance, followed by settlement between the winner of the previous encounter and the bystander.     

Evidence for separate perceptive and semantic memories for odours: a priming experiment

Sixty-four subjects participated in an olfactory priming experiment comprising separate study and test phases. Priming was measured within the olfactory modality (intramodal condition) and from the visual modality to the olfactory modality (intermodal condition). In the study phase of the intramodal condition, subjects were exposed twice to a series of odours: once performing a semantic orientation task (deciding which of seven categories odour stimuli belonged to) and once performing a perceptual orientation task (judging the intensity, the hedonicity and the familiarity of odour stimuli). Half of the odour stimuli corresponded to edible products, the other half did not. The study phase of the intermodal condition was similar, with the exception that the names of the odours (instead of the odours themselves) were presented. In the test phase, subjects were presented with primed and non-primed odour targets and had to decide as fast as possible whether the target corresponded to an edible product or not. Response times and types were recorded by a computer. The analysis of response times revealed a priming effect in the intramodal condition only. Results are discussed in terms of separate perceptual and semantic subsystems that store odour representations.     

The acute effects of mechanical vibration on power output in the bench press

This study was designed to investigate the effect of mechanical vibration on acute power output in the bench press exercise. Ten male subjects who were experienced in resistance training participated in this study. Each subject performed 3 sets of 3 repetitions in the bench press exercise using a load equal to 70% of 1 repetition maximum in each of 2 sessions separated by 3 days. One session served as the experimental (vibration) condition, whereas the other session served as the control (no vibration) condition. The intervention (vibration or control) was applied between sets 2 and 3. The vibration was applied by a vibrating barbell apparatus held by the subjects while lying supine on a bench. The only difference between the 2 conditions was the vibration of the barbell apparatus during the vibration condition. Peak and average power were calculated during each bench press set to determine whether power output differed following vibration compared to control. Average power was significantly higher for the vibration condition compared to the control (525 +/- 74 vs. 499 +/- 71 W; p = 0.01). There was also a trend toward an increase in peak power in the vibration condition (846 +/- 168 by vs. 799 +/- 149 W; p = 0.06). In general, peak and average power output were higher following the vibration intervention compared to control. However, the sets prior to vibration application during the vibration condition also demonstrated higher power outputs compared with the control condition, which contributed to the main effect for the vibration condition. These results suggest that factors other than the vibration intervention influenced task performance during the vibration condition. We suggest that psychological factors related to the novelty of the vibration intervention were involved. These factors may partially explain the conflicting results of previous investigations that examined vibration as an exercise intervention.     

Factors influencing the quick onset of stepping following postural perturbation.

It has been shown that the stepping to recover balance following a forward fall occurs at a constant time (on average 293 ms) (Do et al. Journal of Biomechanics 15, 1982, 933-939). In this study, we tested the hypothesis according to which programming to make fast movement could trigger the movement earlier than when programming self-pace movement. The same experimental paradigm of forward fall was used (see Do et al., 1982) to induce stepping. Different extents of stepping were manipulated by instructions: Subjects were instructed to step to recover their balance naturally (control condition); to make shorter steps than in the control condition; longer steps; faster steps. Lastly, a fast step was also induced by the biomechanical constraint on the initial posture, i.e. by inclining the subject forward at his maximum capacity. Data were collected from 12 subjects. The variables analyzed were the onset latency of step execution and other classical parameters (time of heel-contact, duration of the swing phase, step length, center of mass progression velocity, and step velocity). The results showed that the onset of stepping was unchanged in the longer- and faster-step conditions, relative to the control condition (mean control value = 280 ms). In contrast, the onset of stepping was significantly earlier in the short-step condition, and when the initial inclination was greater (250 and 252 ms, respectively). The swing phase duration in these two conditions averaged 140 and 185 ms, was significantly shorter than in the other conditions, whereas step length was obviously expected to be shorter in the shorter-step condition and longer in the longer-step condition than in the other conditions. Step length was similar between the other conditions. We conclude that neither step length or step velocity programming could induce an earlier onset latency of stepping. Step programming in relation to these specific instructions seemed to concern the extent of step execution and not the time of triggering of the stepping. We suggest that the control of short swing phase duration resulted in an earlier onset latency of stepping to recover the balance. This control depends on the combination of biomechanical constraints and cognitive processes, including subject's interpretation of the instructions and evaluation of the risk of fall.     

Testing Cort-Fitness and Cort-Adaptation hypotheses in a habitat suitability gradient for roe deer

According to the Cort-Fitness Hypothesis, higher stress levels (glucocorticoids) in vertebrates are correlated to lower fitness. However, recent studies have failed to validate this hypothesis. A proposed wider framework suggests that reproduction can be perceived as an overload adds up to other environmental challenges that individuals must adjust to. In this case, elevated glucocorticoids could help individuals to allocate resources to reproduction without comprising other functions, leading to the expectation of a positive cort-fitness relationship. This has been proposed as the Cort-Adaptation Hypothesis. Stress levels result from a complex interaction between the environment and the neuroendocrine system of animals. Accounting for physiological functions involved in how animals cope with their environment would help to clarify the relationship between glucocorticoids and animal performance. We used roe deer (Capreolus capreolus) inhabiting diverse habitats in the Iberian Peninsula to: i) test the Cort-Fitness and Cort-Adaptation hypotheses by indexing fitness using a comprehensive physiological approach which takes into account fundamental physiological functions and their trade-offs; and ii) evaluate the link between primary productivity and individuals' condition in a seasonal environment. We evaluated spatial and temporal variation in stress levels, reproductive hormone levels, nutritional status and immune function from fecal samples collected in 2010. Lower stress levels were related to better condition in non-reproductive seasons but not to higher primary productivity. In contrast, stress levels were always positively related to reproductive condition, which was better in most productive habitats. Summer and winter were the less productive seasons and the more challenging for the species in the habitat gradient studied. In winter, reproductive condition traded off against immune function being biased toward immune function in less productive habitats. In summer reduced primary productivity limited roe deer nutritional and immunological condition but not reproductive condition. Overall our results match both the Cort-Fitness and Cort-Adaptation Hypotheses.     

“Let Me Hear Your Handwriting!” Evaluating the Movement Fluency from Its Sonification

The quality of handwriting is evaluated from the visual inspection of its legibility and not from the movement that generates the trace. Although handwriting is achieved in silence, adding sounds to handwriting movement might help towards its perception, provided that these sounds are meaningful. This study evaluated the ability to judge handwriting quality from the auditory perception of the underlying sonified movement, without seeing the written trace. In a first experiment, samples of a word written by children with dysgraphia, proficient children writers, and proficient adult writers were collected with a graphic tablet. Then, the pen velocity, the fluency, and the axial pen pressure were sonified in order to create forty-five audio files. In a second experiment, these files were presented to 48 adult listeners who had to mark the underlying unseen handwriting. In order to evaluate the relevance of the sonification strategy, two experimental conditions were compared. In a first ‘implicit’ condition, the listeners made their judgment without any knowledge of the mapping between the sounds and the handwriting variables. In a second ‘explicit’ condition, they knew what the sonified variables corresponded to and the evaluation criteria. Results showed that, under the implicit condition, two thirds of the listeners marked the three groups of writers differently. In the explicit condition, all listeners marked the dysgraphic handwriting lower than that of the two other groups. In a third experiment, the scores given from the auditory evaluation were compared to the scores given by 16 other adults from the visual evaluation of the trace. Results revealed that auditory evaluation was more relevant than the visual evaluation for evaluating a dysgraphic handwriting. Handwriting sonification might therefore be a relevant tool allowing a therapist to complete the visual assessment of the written trace by an auditory control of the handwriting movement quality.     

What triggers seizures in the gerbil, Meriones Unguiculatus?

To determine the nature of the stimulus triggering seizures in gerbils, the effectiveness of Novelty (a strange environment), of Extra Stimulation (swinging by the tail) and of Extra Stimulation plus Novelty was tested in 36 subjects. All conditions triggered some seizures but the Novel condition and the Extra Stimulation plus Novel condition, while not differing from each other, were significantly more effective than the Extra Stimulation condition alone. However, in subjects with 6 or more seizures (highly-seizure prone subjects) all 3 conditions were almost equally effective. In those with 4 seizures or less (mildly-seizure prone subjects) the Extra Stimulation plus Novel Condition was the most effective while the Extra Stimulation condition was the least effective. Thus novelty in the form of a strange environment appears to be the most effective means of triggering seizures in gerbils. It is suggested, however, that its effectiveness (as well as that of other seizure-inducing stimuli) is directly related to its stress-inducing properties.     

A 350-S recovery period does not necessarily allow complete recovery of peak power output during repeated cycling sprints

The aim of this study was to determine whether a 350-s recovery period allows recovery of peak power output (PPO) to its initial value under the condition of a blood lactate (La) concentration higher than 10 mmol.L-1 during repeated cycling sprints (RCS). RCS (10x10-s cycling sprints) were performed under two conditions. Under one condition, the recovery period of RCS was fixed at 35 s (RCS35), and under the other condition, a 350-s recovery period was set before the 5th and 9th sets, and a 35-s recovery period was set before the other sets (RCScomb). In RCScomb, PPO in the 5th set recovered to that in the 1st set, but PPO in the 9th set did not. Under both conditions, blood La concentration progressively increased and reached approximately 14 mmol.L-1 at the end of the RCS. In RCScomb, VO2 immediately before the 5th set was not significantly different from that immediately before the 9th set. Mean power frequency (MPF) values estimated by a surface electromyogram from the vastus lateralis in the 5th and 9th sets were significantly higher in RCScomb than in RCS35. In conclusion, a 350-s recovery period does not allow recovery of PPO to its initial value under the condition of a blood La concentration of 14 mmol.L-1 during RCS.     

Changes in body condition and body size affect breeding and recruitment in fluctuating house mouse populations in south‐eastern Australia

Changes in body condition and body size in field populations of house mice, Mus domesticus, were examined to investigate why mouse populations do not increase rapidly in some years when favourable environmental and demographic conditions indicate they might. Mice had repeated seasonal patterns each year in breeding, growth rates and body condition that reflected the seasonal availability of food, but mean levels for each parameter varied among years. In most years mice lost body condition during summer, breeding declined and population growth slowed. Rapid population growth occurred when body condition was generally high and was maintained throughout summer. Female mice with large body length were more likely to breed than smaller mice, at all times, but changes in body condition accounted for most of the variability in female breeding activity between years and between habitats, and for the seasonal changes in the importance of body length. During rapid population growth, the recruitment rate of juveniles relative to the number of breeding females was 150–300% higher than in other years but adult survival rates were not higher. The data indicate that the ability of mice to maintain body condition, particularly when subject to moisture stress in summer, affects the proportion of females breeding, the number of juveniles weaned and their body condition at weaning, and is promoted by foraging conditions that favour maintenance of juvenile body condition after weaning. These factors, in turn, greatly affect juvenile recruitment rates and eventual population density of mice. Low juvenile survival is suggested as a reason that numbers of house mice in southern Australian cereal‐growing areas do not increase rapidly in some years when other parameters are favourable. Similar processes are likely to play a role in regulating other rodent populations.     

Shell fights in the hermit crabPagurus geminus: Aggressive act with mutual gain

The shell exchange of the hermit crabPagurus geminus was investigated to see whether it is based on negotiation (Hazlett 1978) or aggression (Elwood & Glass 1981) between the 2 interactants. Two conditions were adopted: the mutualistic condition in which both participants gain from resulting shell exchange, and the competitive condition in which one interactant gains at the expense of the other. The assumption is that if the interactants negotiate, then a higher, and/or quicker, rate of shell exchanges occurs in the mutualistic condition than in the competitive condition. Almost all the defenders (smaller crabs) were evicted from their shells in both of the conditions. No significant difference was detected in the fight time between the conditions, suggesting a low probability of negotiation. In the second experiment, the attackers (larger crabs) were deprived of the use of their chelipeds, allowing me to observe defenders' behavior when they were not subjected to forced eviction. In this case, the defenders evacuated their shells significantly more quickly under competitive conditions, but remained in the shell much longer under the mutualistic condition, indicating that the shell exchange of this species involves no negotiation. The function of shell rapping and the possibilitics of mutual gain in the aggressive interaction are discussed.     

Fixed interval and fixed time treadle pressing in the pigeon: A comparison with FI and FT keypecking

Experiment I used non-naive pigeons having previously performed on both keypecking and treadlepressing Fixed Interval schedules. In condition IT, treadlepressing was reinforced on successive Fixed Interval 60 seconds, Fixed Time 60 seconds and Fixed Interval 60 seconds schedules. Subsequently (condition IK), the same subjects pecked a key on an identical schedule sequence (FI60, FT60, FI60). In Experiment II, separate groups of naïve subjects were assigned either to treadlepressing (condition IIT) or keypecking (condition IIK) and to the same schedule sequence (FI60, FT60, FI60). Treadle pressing and keypecking decreased greatly in Fixed Time schedules. Curvature indices, pauses and running rates were less sensitive than response rates to the switching from one schedule to the other. Experiments I and II yielded similar results, experimental history accounting only for minor differences. The results were discussed in relation to interspecies differences in the temporal regulation of behavior and operant versus respondent control of the response and schedule-induced behaviour.     

Photoperiodic studies on growth and development of Impatiens balsamina L.

Summary Seedlings of Impatiens balsamina raised under ND and LD conditions were divided into two sub-groups each when they had reached 5-leaf stage. While one sub-group was left under the same condition (NDND or LDLD), the other was transferred to the other photoperiod (NDLD or LDND). NDND plants were subdivided into 2 lots. One of these was transferred to SD in May. The dates of emergence of individual branches and floral buds were recorded and the vegetative period was calculated in each case.It was found that in NDND plants floral buds were produced from all the nodes except the lowermost which produced a single vegetative branch. In LDND plants the vegetative branches were produced from the lower 9 nodes but floral buds from those above these. Small leafy structures which ultimately dried up were produced from a few top nodes in both these cases. In contrast to this in LDLD plants only vegetative branches were produced from all the nodes. In NDLD plants floral buds were produced from the lower 3–5 nodes prior to transfer to LD condition, but vegetative branches were produced from the upper nodes after this transfer. Even some of the lower floral buds reverted to vegetative state under this condition.The production of floral buds or the vegetative branches as the case may be, occurred in acropetal succession under all the photoperiodic conditions and never in basipetal manner.LDLD and NDLD plants, which did not flower at all, continued to produce lateral branches without showing any sign of senescence, while LDND and NDND ones showed yellowing of the apical growing point which spread downwards and lead ultimately to the death of the plant. The senescence was hastened when these plants were transferred to SD condition towards the end of May. The senescence therefore, appears to be related with reproductive development. The results are discussed in the light of current literature.     

Trichodina sp. (Ciliophora: Peritrichida) in eel Anguilla anguilla in recirculation systems in denmark: host-parasite relations

Farmed eel cultured in recirculation systems in Denmark were found infected by Trichodina jadranica Raabe, 1958. Associations between parasite abundance and fish size was examined in 2 different production systems. In one system, stocked with relatively well-nourished eels (3 to 31 g), most of the parasites (66%) were found on the dorsal part on the skin and relatively few were found on the gills (approx. 8%). The infection level was significantly positively correlated both with fish weight and length. In the other system, stocked with relatively malnourished small eels (0.5 to 4 g), significantly more parasites (0.06 +/- 0.02 [SD]) were present on fish with a low condition factor than on fish with a higher condition factor (0.13 +/- 0.01 [SD]). In this eel stock the vast majority of the trichodines were found on the gills.     

The effects of temporary cover on the behavior of socially housed stumptailed macaques (Macaca arctoides)

To examine the effects of the provision of temporary cover on the behavior of stumptailed macaques (Macaca arctoides), a single group of 26 animals was observed during 25 testing periods over 7.5 months. During each testing period, the group was observed under two conditions. In the Cover condition, two solid temporary walls 9.6 m in length, were erected within the animals' living compound. In the No-Cover condition, the wall materials were stacked against one solid exterior wall of the compound. The provision of cover significantly reduced the levels of contact aggression, proximity between animals, and locomotion, and reduced the ability of the dominant male to monopolize copulations. It did not effect other measures of affiliation. Inconsistencies between these results and those of other published studies suggest that, while cover can have a significant influence on some kinds of social behavior in some situations, generalizations about the benefits of providing cover to captive animals may be premature.     

Can We Dissociate Contingency Learning from Social Learning in Word Acquisition by 24-Month-Olds?

We compared 24-month-old children’s learning when their exposure to words came either in an interactive (coupled) context or in a nonsocial (decoupled) context. We measured the children’s learning with two different methods: one in which they were asked to point to the referent for the experimenter, and the other a preferential looking task in which they were encouraged to look to the referent. In the pointing test, children chose the correct referents for words encountered in the coupled condition but not in the decoupled condition. In the looking time test, however, they looked to the targets regardless of condition. We explore the explanations for this and propose that the different response measures are reflecting two different kinds of learning.     

Relations among birth condition, maternal condition, and postnatal growth in captive common marmoset monkeys (Callithrix jacchus)

The present study characterizes the relations among maternal condition, litter size, birth condition, and growth in body weight for a population of common marmosets. The subjects of the study were marmosets born into a single colony between 1994 and 2001. Three sets of analyses were conducted to answer the following questions: 1) Is there a relationship between litter size, maternal condition, and birth condition? In the study population, maternal body weight, maternal age, litter size, and birth condition were related in a complex fashion. Birth weight and prenatal long‐bone growth, as reflected in knee–heel length, were both related to maternal age, with older mothers supporting higher prenatal growth. Age and maternal condition appeared to interact as determinants of long‐bone growth, as the combination of older and larger mothers resulted in significantly longer knee–heel lengths in their offspring. 2) Is there a relationship between birth condition or maternal condition and subsequent growth or final adult size? The early growth rate in this population was similar to early growth rates reported for three different marmoset colonies, suggesting that early growth may be relatively inflexible in this species. However, within this population, the variation that did occur in early growth rate was related to birth weight and maternal weight. Later growth and adult weight were related to birth weight and litter size: small twin infants displayed slower later growth rates and were smaller as adults than twins that began life at a higher birth weight, while the birth weight of triplets was not related to adult size. In these marmosets, small infants that were the result of increased litter size differed from small infants whose small birth size resulted from other factors. This reinforces the proposal that the causes of low birth weight will be relevant to the development of the marmoset as a model of prenatal environmental effects. Am. J. Primatol. 62:83–94, 2004. © 2004 Wiley‐Liss, Inc.