Experimental and Theoretical Search for a Phase Transition in Nuclear Fragmentation

Phase transitions of small isolated systems are signaled by the shape of the caloric equation of state e^*(T), the relationship between the excitation energy per nucleon e^* and temperature. In this work we compare the experimentally deduced e^*(T) to the theoretical predictions. The experimentally accessible temperature was extracted from evaporation spectra from incomplete fusion reactions leading to residue nuclei. The experimental e^*(T) dependence exhibits the characteristic S-shape at e^* = 2-3 MeV/A. Such behavior is expected for a finite system at a phase transition. The observed dependence agrees with predictions of the MMMC-model, which simulates the total accessible phase-space of fragmentation

Robust retention and transfer of tool construction techniques in chimpanzees (Pan troglodytes)

Long-term memory can be critical to a species’ survival in environments with seasonal and even longer-term cycles of resource availability. The present, longitudinal study investigated whether complex tool behaviors used to gain an out-of-reach reward, following a hiatus of about 3 years and 7 months since initial experiences with a tool use task, were retained and subsequently executed more quickly by experienced than by naïve chimpanzees. Ten of the 11 retested chimpanzees displayed impressive long-term procedural memory, creating elongated tools using the same methods employed years previously, either combining 2 tools or extending a single tool. The complex tool behaviors were also transferred to a different task context, showing behavioral flexibility. This represents some of the first evidence for appreciable long-term procedural memory, and improvements in the utility of complex tool manufacture in chimpanzees. Such long-term procedural memory and behavioral flexibility have important implications for the longevity and transmission of behavioral traditions

Sex Differences in the Relationship Between Planum Temporale Asymmetry and Corpus Callosum Morphology in Chimpanzees (\u3cem\u3ePan troglodytes\u3c/em\u3e): A Combined MRI and DTI Analysis

Increases brain size has been hypothesized to be inversely associated with the expression of behavioral and brain asymmetries within and between species. We tested this hypothesis by analyzing the relation between asymmetries in the planum temporale (PT) and different measures of the corpus callosum (CC) including surface area, streamline count as measured from diffusion tensor imaging, fractional anisotropy values and the ratio in the number of fibers to surface area in a sample of chimpanzees. We found that chimpanzees with larger PT asymmetries in absolute terms had smaller CC surface areas, fewer streamlines and a smaller ratio of fibers to surface area. These results were largely specific to male but not female chimpanzees. Our results partially support the hypothesis that brain asymmetries are linked to variation in corpus callosum morphology, although these associations may be sex-dependent

Hand Preference for Coordinated Bimanual Actions in 777 Great Apes: Implications for the Evolution of Handedness in Hominins

Whether or not nonhuman primates exhibit population-level handedness remains a topic of considerable scientific debate. Here, we examined handedness for coordinated bimanual actions in a sample of 777 great apes including chimpanzees, bonobos, gorillas, and orangutans. We found population-level right-handedness in chimpanzees, bonobos and gorillas, but left-handedness in orangutans. Directional biases in handedness were consistent across independent samples of apes within each genus. We suggest that, contrary to previous claims, population-level handedness is evident in great apes but differs among species as a result of ecological adaptations associated with posture and locomotion. We further suggest that historical views of nonhuman primate handedness have been too anthropocentric, and we advocate for a larger evolutionary framework for the consideration of handedness and other aspects of hemispheric specialization among primates

Granulovacuolar Degeneration in Brains of Senile Cynomolgus Monkeys

Neurons with histopathological changes consistent with granulovacuolar degeneration (GVD) were found in brain sections from aged cynomolgus monkeys (Macaca fascicularis) with clinical and pathological signs of cognitive aging. To our knowledge, this is the first reported description of GVD in non-human primates. GVD-like lesions were found also in age-matched cognitively healthy subjects, albeit in lower numbers, suggesting that they may relate to aging and the increase may have tendency to increase with the memory deficits. The increased incidence of GVD-like lesions in memory-impaired subjects with pahological backgrounds of senile plaques (SPs) and tauopathy is, however, an interesting observation of relevance to the characterization of pathologies in the spontaneous cynomolgus monkey model of human Alzheimer’s type of brain pathology

Identificación de nematodos gastrointestinales en búfalos faenados en un frigorífico de Corrientes, Argentina

The objective of this work was to identify and quantify the adult specimens of gastrointestinal nematodes in buffaloes slaughtered in Virasoro (Corrientes, Argentina) by means of necropsy of the digestive tract, and through coprological studies, in order to correlate them with the count of eggs per gram of fecal stool and the proportion of parasite genera of third stage larvae of stool culture. A total of 4 necropsies corresponding to young male buffaloes were carried out, of which 50% presented adult specimens of Trichostrongylus sp and Haemonchus sp located only in the abomasum. In the coprological studies, 75% of the samples presented counts of egg per gram of fecal stool, with only 2 cases with the identification of third stage larvae of Haemonchus sp in stool cultures.El objetivo del trabajo fue identificar y cuantificar los ejemplares adultos de nematodos gastrointestinales en los búfalos faenados en el frigorífico de Virasoro (Corrientes) mediante la necropsia parasitaria del tubo digestivo y, por intermedio de estudios coprológicos, correlacionarlos con el recuento de huevos por gramo de materia fecal y la proporción de géneros parasitarios de larvas de tercer estadio de los coprocultivos. Se realizaron en total 4 necropsias parasitarias que correspondieron a búfalos machos jóvenes, de los cuales el 50% presentó ejemplares adultos de Trichostrongylus sp y Haemonchus sp ubicados solamente en el abomaso. En los estudios coprológicos, el 75% de las muestras presentaron recuentos de huevos por gramo de materia fecal, de los cuales únicamente en dos casos se pudieron identificar larvas de tercer estadio de Haemonchus sp en los coprocultivos

A large geometric distortion in the first photointermediate of rhodopsin, determined by double-quantum solid-state NMR

Double-quantum magic-angle-spinning NMR experiments were performed on 11,12-C-13(2)-retinylidene-rhodopsin under illumination at low temperature, in order to characterize torsional angle changes at the C11-C12 photoisomerization site. The sample was illuminated in the NMR rotor at low temperature (similar to 120 K) in order to trap the primary photointermediate, bathorhodopsin. The NMR data are consistent with a strong torsional twist of the HCCH moiety at the isomerization site. Although the HCCH torsional twist was determined to be at least 40A degrees, it was not possible to quantify it more closely. The presence of a strong twist is in agreement with previous Raman observations. The energetic implications of this geometric distortion are discussed

Resistencia a los antihelmínticos en bovinos del nordeste de Corrientes (Argentina)

El objetivo del trabajo fue determinar la prevalencia de la resistencia a los antiparasitarios contra los nematodes gastrointestinales de bovinos en el nordeste de Corrientes. El área de estudio comprendió 4 establecimientos ganaderos de los departamentos Ituzaingó y Santo Tomé. El periodo de estudio abarcó de marzo de 2014 a agosto de 2016. La unidad de análisis fue el ternero destete. El método utilizado fue el test de reducción del conteo de huevos. La prevalencia de la resistencia antihelmíntica a la ivermectina en los 4 establecimientos ganaderos muestreados en este estudio fue del 100% y para el benzimidazol fue del 25%. Los géneros parasitarios resistentes a la ivermectina fueron Haemonchus y Cooperia. Estos resultados demuestran un aumento de la resistencia antihelmíntica si se comparan con estudios previos realizados en otros lugares del país