Size Matters: Impact of Item Size and Quantity on Array Choice by Chimpanzees (Pan troglodytes)

The authors previously reported that chimpanzees (Pan troglodytes) showed a striking bias to select the larger of 2 candy arrays, despite a reversed reward contingency in which the animals received the smaller, nonselected array as a reward, except when Arabic numerals were used as stimuli. A perceptual or incentive-based interference occurred that was overcome by symbolic stimuli. The authors of the present study examined the impact of element size in choice arrays, using 1 to 5 large and small candies. Five test-sophisticated chimpanzees selected an array from the 2 presented during each trial. Their responses were not optimal, as animals generally selected arrays with larger total mass; thus, they received the smaller remaining array as a reward. When choice stimuli differed in size and quantity, element size was more heavily weighted, although choices reflected total candy mass. These results replicate previous findings showing chimpanzees\u27 difficulties with quantity judgments under reverse reward contingencies and also show that individual item size exerts a more powerful interference effect

On the boundary of the dispersion-managed soliton existence

A breathing soliton-like structure in dispersion-managed (DM) optical fiber system is studied. It is proven that for negative average dispersion the breathing soliton is forbidden provided that a modulus of average dispersion exceed a threshold which depends on the soliton amplitude.Comment: LaTeX, 8 pages, to appear in JETP Lett. 72, #3 (2000

Auditory ERPs to Stimulus Deviance in an Awake Chimpanzee (Pan troglodytes): Towards Hominid Cognitive Neurosciences

BACKGROUND: For decades, the chimpanzee, phylogenetically closest to humans, has been analyzed intensively in comparative cognitive studies. Other than the accumulation of behavioral data, the neural basis for cognitive processing in the chimpanzee remains to be clarified. To increase our knowledge on the evolutionary and neural basis of human cognition, comparative neurophysiological studies exploring endogenous neural activities in the awake state are needed. However, to date, such studies have rarely been reported in non-human hominid species, due to the practical difficulties in conducting non-invasive measurements on awake individuals. METHODOLOGY/PRINCIPAL FINDINGS: We measured auditory event-related potentials (ERPs) of a fully awake chimpanzee, with reference to a well-documented component of human studies, namely mismatch negativity (MMN). In response to infrequent, deviant tones that were delivered in a uniform sound stream, a comparable ERP component could be detected as negative deflections in early latencies. CONCLUSIONS/SIGNIFICANCE: The present study reports the MMN-like component in a chimpanzee for the first time. In human studies, various ERP components, including MMN, are well-documented indicators of cognitive and neural processing. The results of the present study validate the use of non-invasive ERP measurements for studies on cognitive and neural processing in chimpanzees, and open the way for future studies comparing endogenous neural activities between humans and chimpanzees. This signifies an essential step in hominid cognitive neurosciences

The impact of informal cancer caregiving: A literature review on psychophysiological studies

Caregiving can be experienced as a stressful process, which can cause psychological and physical consequences. The combination of prolonged stress and the physical demands of caregiving may impair the physiological functioning of caregivers and increase the risk of health problems creating considerable stress in the life of caregivers regarding emotional, physical, social and financial areas. This literature review explored studies that used measures of the autonomic nervous system in caregivers of oncology patients such as electrodermal and cardiovascular (re)activity. The results revealed that caregivers had elevated stress levels and a serious autonomic imbalance that may, in the long term, trigger negative health consequences such as infectious diseases, cancer progression, cardiovascular disease and even premature death. The results showed the need to carry out preventive strategies in this population, in order to improve the autonomic profile of caregivers of cancer patients

HLA-B27 predicts a more extended disease with increasing age at onset in boys with juvenile idiopathic arthritis

Poster presentatiopn at 15th Paediatric Rheumatology European Society (PreS) Congress London, UK. 14–17 September 200

Temporomandibular joint damage in juvenile idiopathic arthritis: Diagnostic validity of diagnostic criteria for temporomandibular disorders

Diagnostic criteria reported in the expanded taxonomy for temporomandibular disorders include a standardised clinical examination and diagnosis (DC/TMD 3.B) of temporomandibular joint (TMJ) damage in patients with juvenile idiopathic arthritis (JIA); however, their validity is unknown