FE-modeling of damage of twill carbon/epoxy composite on meso-scale, materials characterization and experimental verification

Aim of this work is to evaluate the damage in twill carbon/epoxy composites on meso-scale level (fabric unit cell level). Averaged stiffness, Poisson ratios of pre- and post damage phase are calculated based on numerical homogenization technique with periodic boundary conditions (PBCs). The static strengths and initiation of the damage are calculated and validated by experiments. The anisotropic stiffness degradation model is implemented into Abaqus (R) UMAT. The algorithm of quasi-static damage is further used to model the cycles of the fatigue loading, together with the experimental S-N curves of unidirectional composite (UD), utilized as input data for the impregnated yarns. The output of the model is S-N curve of textile composites

First record in Argentina of Drepanosiphum oregonense Granovsky (Hemiptera: Aphididae) found on maples (Sapindaceae)

Se informa del hallazgo del áfido Drepanosiphum oregonense Granovsky (Hemiptera: Aphididae) sobre árboles de Acer pseudoplatanus y A. campestre (Sapindaceae) en Argentina lo que constituye el primer registro de la especie y del género Drepanosiphum Koch en Argentina y el segundo en Sudamérica.The finding in Argentina of the aphid Drepanosiphum oregonense on "maple tree" Acer pseudoplatanus and A. campestre is reported. This report constitutes the first record of this species and of the genus Drepanosiphum Koch from Argentina and the second one from South America.Fil: Ortego, Jaime. Instituto Nacional de Tecnología Agropecuaria (Argentina). Estación Experimental Agropecuaria Mendoza.Fil: Olave, Anabel. Universidad Nacional del Comahue. Facultad de Ciencias AgrariasFil: Mier Durante, M. Pilar. Universidad de León. Departamento de Biodiversidad y Gestión Ambienta

Organisation of α2c-adrenergic receptors in spinal pain pathways

The α2c-subclass of adrenergic receptor mediates some of the antinociceptive actions of noradrenaline in the spinal cord. This receptor is present on axon terminals in the superficial dorsal horn. A series of double-labelling experiments for confocal microscopy was performed in the rat (Wistar) to investigate the relationship between the α2c -adrenergic receptor and each of seventeen chemical markers that label various types of axon terminal in the dorsal horn. Quantitative analysis revealed that α2c -adrenergic receptors are neither present on terminals of unmyelinated, myelinated or peptidergic primary afferents nor on descending noradrenergic or serotoninergic terminals, whereas they are present on terminals of spinal origin. α2c -adrenergic receptors are predominantly found on axon terminals of excitatory interneuronal populations and also to a lesser extent they are present on terminals of inhibitory interneurons, hi addition, the receptor is present on terminals that contain certain peptides, which indicates that subpopulations of interneurons possessing the α2c -adrenergic receptor can be differentiated on the basis of their peptidergic content. Electron microscopic analysis revealed that imnunoreactivity is predominantly associated with axon terminals that are presynaptic to dendrites while a small proportion of immunoreactive terminals formed axoaxonic synaptic arrangements. Experimental techniques were combined in order to investigate the relationship of terminals possessing α2c -adrenergic receptors with supraspinally projecting neurons. The techniques included retrograde labelling, multiple and sequential-immunolabelling, correlated confocal-electron microscopy and induction of the immediate early gene c-Fos by peripheral noxious stimulation. The findings indicated that axon terminals containing the α2c -adrenergic receptor densely innervate spinomedullary neurons that express the substance P receptor, neurokinin-1. The latter terminals are glutamatergic (excitatory) and form synapses with this type of neuron. In addition, a substantial number of neurokinin-1 projection neurons in lamina I that are responsive to peripheral thermal noxious stimulation, i.e. express c-Fos, receives innervation from axon terminals containing α2c - adrenergic receptors. The α2c -adrenergic receptor is also present in axon terminals in the lateral spinal nucleus. This nucleus is found in the rat and other rodents and contains projection neurons that are densely innervated by peptidergic varicosities. Double-labelling immunostaining experiments showed that α2c -adrenergic receptors are present on axon terminals of mainly excitatory interneurons but also of inhibitory interneurons, and frequently contain peptides. Electron microscopy revealed that terminals possessing the receptor are presynaptic to dendrites and somata of neurons in the lateral spinal nucleus. The involvement of lateral spinal nucleus neurons in nociceptive transmission and their relationship with axons that possess α2c -adrenergic receptors was investigated. By combining retrograde labelling of projection neurons with induction of c-Fos expression by peripheral noxious stimulation and multiple-immunolabelling, it was possible to identify NK-1 projection neurons in the lateral spinal nucleus that express c-Fos and to determine if such cells receive contacts from terminals possessing the α2c receptor. The results show that neurons in this nucleus are densely innervated by axons that possess the receptor and that a small proportion can be activated by thermal noxious stimulation. In conclusion, noradrenaline is likely to modulate nociceptive transmission by acting on terminals of interneurons that contain the α2c -adrenergic receptor in the superficial dorsal horn and also in the lateral spinal nucleus

Estimating the maximum sustainable yield of bonito (Sarda chiliensis, Scombridae) of northern Chile from monthly catch data

Monthly catch data of bonito Sarda chiliensis from northern Chile, from 1976 to 1989, were used to obtain a series of estimates of the Z-G parameter (i.e., total mortality minus the growth coefficient in weight). This series was then used to estimate a maximum sustainable yield of 4,500 t/year through a modified version of the surplus production model of J. Csirke and J. Caddy. The status of the fishery is discussed

Chronic Stress Triggers Expression of Immediate Early Genes and Differentially Affects the Expression of AMPA and NMDA Subunits in Dorsal and Ventral Hippocampus of Rats

Indexación: Web of Science; Scopus.Previous studies in rats have demonstrated that chronic restraint stress triggers anhedonia, depressive-like behaviors, anxiety and a reduction in dendritic spine density in hippocampal neurons. In this study, we compared the effect of repeated stress on the expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptor subunits in dorsal and ventral hippocampus (VH). Adult male Sprague-Dawley rats were randomly divided into control and stressed groups, and were daily restrained in their motion (2.5 h/day) during 14 days. We found that chronic stress promotes an increase in c-Fos mRNA levels in both hippocampal areas, although it was observed a reduction in the immunoreactivity at pyramidal cell layer. Furthermore, Arc mRNAs levels were increased in both dorsal and VH, accompanied by an increase in Arc immunoreactivity in dendritic hippocampal layers. Furthermore, stress triggered a reduction in PSD-95 and NR1 protein levels in whole extract of dorsal and VH. Moreover, a reduction in NR2A/NR2B ratio was observed only in dorsal pole. In synaptosomal fractions, we detected a rise in NR1 in dorsal hippocampus (DH). By indirect immunofluorescence we found that NR1 subunits rise, especially in neuropil areas of dorsal, but not VH. In relation to AMPA receptor (AMPAR) subunits, chronic stress did not trigger any change, either in dorsal or ventral hippocampal areas. These data suggest that DH is more sensitive than VH to chronic stress exposure, mainly altering the expression of NMDA receptor (NMDAR) subunits, and probably favors changes in the configuration of this receptor that may influence the function of this area.https://www.frontiersin.org/articles/10.3389/fnmol.2017.00244/ful

Communicating Arteries of the Cerebral Arterial Circle: Biometric Features and their Relation with the Cephalic Index

Indexación: ScieloLa clínica neuroquirúrgica tiene la necesidad de un acabado conocimiento anatómico de las arterias comunicantes como integrantes del círculo arterial del cerebro, por su variabilidad morfológica, su relación compleja con las estructuras adyacentes y por la alta frecuencia observada en la conformación de aneurismas. Debido a la importancia de estos vasos, efectuamos un estudio biométrico de los mismas, relacionando datos de calibre y longitud con índice cefálico. En el sexo masculino, el calibre promedio de la ACoP fue de 1,07 mm en el lado derecho y de 1,06 mm en el izquierdo; en el sexo femenino fue de 1,12 mm en el lado derecho y de 1,14 mm en el izquierdo. En el grupo de individuos con índice braquicéfalo, el calibre de la ACoP fue de 1,15 mm y en el grupo dolicomesocéfalo fue de 1,05 mm. Su longitud fue de 18,65 mm en los braquicéfalos y de 16,44 mm en los dolicomesocéfalos.El calibre de la ACoA fue de 1,53 mm en el sexo masculino y de 1,05 mm en el femenino, mientras que su longitud fue de 2,81 mm en el sexo masculino y de 2,33 mm en el femenino.La descripción biométrica y bioantropológica muestra parámetros importantes a considerar en la clínica quirúrgica. PALABRAS CLAVE : Anatomía; Biometría; Círculo arterial cerebral; Arterias comunicantes; Indice cefálico. -------------------------------------------------------------------------------- RESUMEN: The neurosurgical clinic needs extensive and thorough anatomical knowledge of the communicating arteries as part of the cerebral arterial circle for their morphological variability, their complex relation as adjacent structures, and for the frequency observed in the formation of aneurisms. Considering the importance of these vessels, we conducted a biometric study of these, relating caliber and longitude information to the cephalic index. In the male, the mean caliber of the PCoA <p was of 1.07 mm on the right side and 1.06 mm on the left; in the female it was of 1.12 mm on the right side and of 1.14 mm on the left. In the group of individuals with brachiocephalic index, the caliber of the ACoP was of 1.15 mm and in the dolichomesocephalic groups was 1.05 mm. Its longitude was 18.65 mm in the brachiocephalous and of 16.44 mm in the dolichomesochephalic. The caliber of the ACoA was of 1.53 mm in the male and 1.05 mm in the female, while its longitude was of 2.81 mm in the male and 2.33 mm in the female. The biometric and bioanthropologic description shows important parameters to be considered in clinical surgery. KEY WORDS : Anatomy; Biometry; Cerebral arterial circle; Communicating arteries; Cephalic index

Not Waving but Striving: Research Collaboration in the Context of Stratification, Segmentation, and the Quest for Prestige

In this article we examine the ways in which institutional stratification and academic labor segmentation contribute to shaping faculty collaborative activities. We draw on interviews from science and engineering faculty at two institutions in the United States to highlight how collaboration, as an essential form of academic labor, is shaped by institutional factors like resource stress and isomorphic pressures to fit the ideal of the “world-class” research-intensive university. The findings suggest that a university’s relative position in the institutional status hierarchy has a significant impact on the types of resources faculty seeking to establish collaborations can access and mobilize, thus reinforcing existing patterns of institutional stratification where “striving” institutions can never catch up to their more prestigious peers. At the same time, the pressure to maximize institutional prestige can create paradoxical interinstitutional dynamics where seemingly successful “Mode 2” units that rely almost exclusively on external resources and partnerships with industry are expected to mold themselves more closely to the activity streams of traditional academic units

Biometrics of the Posterior Communicating Artery and the Posterior Cerebral Artery in its Precommunicating Segment (P1) of the Arterial Circle of Brain (Willis)

Indexación: ScieloEl conocimiento anatómico y clínico preciso del círculo arterial del cerebro, se hace cada vez más necesario, por la compleja relación neural que presentan las diversas arterias que entran en su formación y además por su gran variabilidad. Utilizamos 36 encéfalos humanos frescos, provenientes de especímenes autopsiados adultos, cuyos datos bioantropológicos fueron previamente registrados. El calibre de las aa. comunicantes posteriores fue, en promedio, de 1,08 mm (DE 0,45 ) en ambos lados y su longitud de 17,51 mm( DE 7,9) en el lado derecho y de 16,9 mm (DE 8,0 ) en el lado izquierdo. La ACP en el segmento P1 presentó un calibre de 2,56 mm (DE 077) en el lado derecho y de 2,32 mm (DE 0,64) en el lado izquierdo. La longitud de estas arterias correspondió a 9,43 mm (DE 8,92) en el lado derecho y de 8,82 mm (DE 7,33 ) en el lado izquierdo. Las dimensiones observadas demuestran variabilidad que consideramos interesante de considerar en la anatomía quirúrgica.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-95022006000500015&lang=p