Measurements and Simulations of nonlinear noise redistribution in an SOA

Measurements and numerical simulations of the noise statistics after a semiconductor optical amplifier (SOA) demonstrate nonlinear noise redistribution. The redistribution, which relies on self-modulation due to gain saturation and carrier dynamics, shows a strong power and bandwidth dependence and can be important for SOA-based regenerators.     

Reduction of intrachannel four-wave mixing using the alternate-phase RZ modulation format

The authors propose a modulation format in which the phase of the signal pulses alternates, in order to reduce the intrachannel four-wave mixing. They demonstrate numerically that the performance of a 40-Gb/s transmission link can be substantially improved.     

Blockage and release of hypothalamically and naturally elicited aggressive behaviors in cats following midbrain lesions.

Measured the hypothalamic thresholds for components of biting attack and threat before and after midbrain lesions in 44 cats. Elicited attack and reflexive biting were blocked by medial tegmental destruction, while spontaneous attack and reflexive biting appeared after lateral tegmental lesions. Results suggest that the areas have independent and partially lateralized projections to lower sensorimotor mechanisms. Dorsal tegmental lesions blocked hypothalamically-elicited ear flattening, lesions along a pathway from central gray to ventrolateral tegmentum blocked all vocalization, and no lesions affected pupillodilation of piloerection. Unilateral lesion effects suggested that pathways between hypothalamus and midbrain are partially crossed, but predominantly homolateral. Results support the view that the hypothalamus produces complex behaviors by acting caudally, through separate pathways, on sensorimotor mechanisms for different components. (25 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of cerebellar lesions on activity, social interactions, and other motivated behaviors in the rat.

In a total of 36 male rats, lesions of the cerebellar fastigial nucleus, but not lateral nuclear lesions or cerebellar cortical lesions, resulted in significant reductions in activity, open-field exploratory behavior, and social interactions. These deficits showed no recovery over a 4-wk testing period and were not related to the motor effects of the lesions. Other motivated behaviors (e.g., eating, grooming, gnawing, and pain responsiveness) were minimally affected. Results suggest the existence of 2 separate fastigial output pathways to neurobehavioral substrates: (a) the direct fastigio-bulbar pathway, which mediates the eating, grooming, and gnawing behaviors elicited by fastigial stimulation, and (b) the ascending fastigial projection to limbic structures, which may mediate fastigial influences on activity and social interaction. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Well-being and organizational attitudes in alternative employment: The role of contract and job preferences.

This study focuses upon the heterogeneity in the contemporary workforce in relation to well-being and organizational attitudes. This heterogeneity may concern (a) the specific type of contract (permanent full-time vs. alternative arrangements; e.g., permanent part-time, fixed-term, and on-call work), (b) job and contract preferences, or (c) specific combinations of contract type and preferences. The authors argue that working in alternative employment, but also being in a nonpreferred contract or job may imply stress and, hence, strain (i.e., poor well-being). This may lead to withdrawal from the organization (i.e., poor organizational attitudes). A combination of the stressors may strengthen these effects. Analyses of questionnaire data from Sweden collected in 2004 (N = 716) reveal that preferences, particularly preferences for the job and partly also for the contract, were associated with the outcomes. Contract heterogeneity was not informative for well-being, while it was for differences in reported organizational attitudes. Type of employment contract interacted with job and contract preferences: for permanent full-time workers, job preferences displayed stronger associations with well-being and attitudes than for workers in alternative employment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social psychological contributions to the decade of the brain: Doctrine of multilevel analysis.

The 1990s were declared by Congress to be the "decade of the brain." This declaration is important to all psychologists, not only neuroscientists, because with this declaration come expectations of the cognitive and behavioral sciences generally and because the brain does not exist in isolation but rather is a fundamental component of developing and aging individuals who themselves are mere actors in the larger theater of life. This article examines the importance of a multilevel, integrative approach to the study of mental and behavioral phenomena in the decade of the brain, reviews how this approach highlights the synergistic relationship between theoretical and clinically relevant research, and illustrates how this approach can foster the transition from microtheories to general psychological theories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Specificity of the cardiac response to conspecific vocalizations in chimpanzees.

Used heart rate measures to examine the functional response of young chimpanzees and orangutans to acoustic stimuli, including white noise and chimpanzee vocalizations (threat, stress, and alarm). The initial response of the Ss to all stimuli was characterized by a cardiac (CAR) deceleration and an increase in heart period variability. The deceleratory responses persisted with repeated presentations of the noise, stress, and alarm stimuli. In contrast, the response of chimpanzees to the conspecific threat stimulus reverted over trials to a notable CAR acceleration. The features of the CAR response, together with the results of frequency-domain analyses of heart period variability, suggest that this acceleratory response was consistent with the evocation of an aversive or a defensive reaction characterized by sympathetic activation. This pattern of CAR response appeared early in ontogeny (within 48 hr postnatally) and was not manifest in orangutans. Taken together, results suggest the existence of specialized perceptual processing mechanisms for vocal stimuli in the chimpanzee. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The decerebrate human: associative learning

Phasic changes in cardiac reactivity to innocuous stimuli, presented in a sensory disparity paradigm, were used to evaluate habituation and learning processes in five decerebrate subjects. Three subjects showed systematic changes over trials in the pattern of cardiac response to simple auditory or visual stimuli, indicative of habituation. In addition, tests for associative learning were given after repeated presentations of two paired stimuli. The appearance of a marked cardiac orienting response, to the unpredictable omission of the second stimulus, documented the development of a conditioned association in these same three subjects. One additional subject failed to show a consistent pattern of response to the stimuli, and another demonstrated a consistent response which was not subject to habituation. Overall, these findings support the view that learning processes are not solely the product of the cerebral hemispheres, but reflect general integrative features of the human neuraxis.     

Indicating acts during counting by a chimpanzee (Pan troglodytes).

A chimpanzee (Pan troglodytes) experienced in counting arrays of 0–7 items and trained for comprehension of number symbols, spontaneously displayed a variety of indicating acts (e.g., pointing, touching, and rearranging items) during counting. Twenty-five sessions were videotaped, and all trials were evaluated for the relations among number of items presented, number of indicating acts displayed, and the Arabic number selected to represent the array. Significant correlations included the relations between number of items and the cardinal number selected by the animal, between the number of items and indicating acts displayed by the chimpanzee, and between the number of indicating acts and the numeral selected. These data suggest that the use of indicating acts by this animal may have functional significance and serves as an organizing schema, comparable to similar behaviors observed in children in the early stages of learning to count. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Just because you're imaging the brain doesn't mean you can stop using your head: A primer and set of first principles.

Developments within the neurosciences, cognitive sciences, and social sciences have contributed to the emergence of social neuroscience. Among the most obvious contemporary developments are brain-imaging procedures such as functional magnetic resonance imaging. The authors outline a set of first principles designed to help make sense of brain-imaging research within the fields of cognitive and social neuroscience. They begin with a principle few would debate--that social cognition, emotion, and behavior involve the brain--but whose implications might not be entirely obvious to those new to the field. The authors conclude that (a) complex aspects of the mind and behavior will benefit from yet a broader collaboration of neuroscientists, cognitive scientists, and social scientists, and (b) social psychologists bring important theoretical, methodological, and statistical expertise to this interdisciplinary enterprise. (PsycINFO Database Record (c) 2010 APA, all rights reserved)