Victor Cousin e l'estetica fotografica nella Francia del xix secolo

Il presente lavoro si occupa di ricostruire il dibattito che ha visto nascere l'estetica fotografica nella Francia del 1839

Parallel pair-wise interaction for multi-agent immune systems modelling

Agent Based Modelling (ABM), is an approach for modelling dynamic systems and studying complex and emergent behaviour. ABM approach is a very common technique in biological domain due to high demand for a large scale analysis tool to collect and interpret information to solve biological problems. However, simulating large scale cellular level models (i.e. large number of agents/entities) require a high degree of computational power which is achievable through parallel computing methods such as Graphics Processing Units (GPUs). The use of parallel approaches in ABMs is growing rapidly specifically when modelling in continuous space system (particle based). Parallel implementation of particle based simulation within continuum space where agents contain quantities of chemicals/substances is very challenging. Pair-wise interactions are different abstraction to continuous space (particle) models which is commonly used for immune system modelling. This paper describes an approach to parallelising the key component of biological and immune system models (pair-wise interactions) within an ABM model. Our performance results demonstrate the applicability of this method to a broader class of biological systems with the same type of cell interactions and that it can be used as the basis for developing complete immune system models on parallel hardware

Parallelisation strategies for agent based simulation of immune systems

Background In recent years, the study of immune response behaviour using bottom up approach, Agent Based Modeling (ABM), has attracted considerable efforts. The ABM approach is a very common technique in the biological domain due to high demand for a large scale analysis tools for the collection and interpretation of information to solve biological problems. Simulating massive multi-agent systems (i.e. simulations containing a large number of agents/entities) requires major computational effort which is only achievable through the use of parallel computing approaches. Results This paper explores different approaches to parallelising the key component of biological and immune system models within an ABM model: pairwise interactions. The focus of this paper is on the performance and algorithmic design choices of cell interactions in continuous and discrete space where agents/entities are competing to interact with one another within a parallel environment. Conclusions Our performance results demonstrate the applicability of these methods to a broader class of biological systems exhibiting typical cell to cell interactions. The advantage and disadvantage of each implementation is discussed showing each can be used as the basis for developing complete immune system models on parallel hardware

Genetic drift at expanding frontiers promotes gene segregation

Competition between random genetic drift and natural selection plays a central role in evolution: Whereas non-beneficial mutations often prevail in small populations by chance, mutations that sweep through large populations typically confer a selective advantage. Here, however, we observe chance effects during range expansions that dramatically alter the gene pool even in large microbial populations. Initially well-mixed populations of two fluorescently labeled strains of Escherichia coli develop well-defined, sector-like regions with fractal boundaries in expanding colonies. The formation of these regions is driven by random fluctuations that originate in a thin band of pioneers at the expanding frontier. A comparison of bacterial and yeast colonies (Saccharomyces cerevisiae) suggests that this large-scale genetic sectoring is a generic phenomenon that may provide a detectable footprint of past range expansions.Comment: Please visit http://www.pnas.org/content/104/50/19926.abstract for published articl

Influence of short-term storage on electrophoretic profile of bovine serum proteins

Storage represents a basic step of the pre-analytical phase for the accuracy of screening tests both in human and veterinary diagnostic laboratories. This study aimed to evaluate the effect of short-term storage on electrophoretic profile of serum proteins in dairy cows. Blood was collected from 18 clinically healthy cows and serum was divided into four aliquots. The first aliquot was immediately analysed (time 0). The second and the third aliquots were stored at +4°C for 24 and 48 h, respectively. The fourth aliquot was frozen at −20° C for 48 hours. A statistical analysis was performed on the obtained data. Albumin and α-globulins relative concentration and A/G ratio showed significant changes after 48 h storage. The results obtained in the current study showed that short-term storage influenced electrophoretic pattern of bovine serum proteins and the A/G ratio. Therefore, the refrigeration of bovine sera for 24 h at the most should be suggested to practitioners in order to obtain reliable serum protein..

Teaching mathematics at distance: A challenge for universities

The focus of this research is how Sicilian state university mathematics professors faced the challenge of teaching via distance education during the first wave of the COVID-19 pandemic. Since the pandemic entered our lives suddenly, the professors found themselves having to lecture using an e-learning platform that they had never used before, and for which they could not receive training due to the health emergency. In addition to the emotional aspects related to the particular situation of the pandemic, there are two aspects to consider when teaching mathematics at a distance. The first is related to the fact that at university level, lecturers generally teach mathematics in a formal way, using many symbols and formulas that they are used to writing. The second aspect is that the way mathematics is taught is also related to the students to whom the teaching is addressed. In fact, not only online, but also in face-to-face modality, the teaching of mathematics to students on the mathematics degree course involves a different approach to lessons (as well as to the choice of topics to explain) than teaching mathematics in another degree course. In order to investigate how the Sicilian State university mathematics professors taught mathematics at distance, a questionnaire was prepared and administered one month after the beginning of the lockdown in Italy. Both quantitative and qualitative analyses were made, which allowed us to observe the way that university professors have adapted to the new teaching modality: they started to appropriate new artifacts (writing tablets, mathematical software, e-learning platform) to replicate their face-to-face teaching modality, mostly maintaining their blackboard teacher status. Their answers also reveal their beliefs related to teaching mathematics at university level, noting what has been an advantageous or disadvantageous for them in distance teaching

Redox regulation of cellular stress response in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune-mediated neurodegenerative disease with characteristic foci of inflammatory demyelination in the brain, spinal cord, and optic nerves. Recent studies have demonstrated not only that axonal damage and neuronal loss are significant pathologic components of MS, but that this neuronal damage is thought to cause the permanent neurologic disability often seen in MS patients. Emerging finding suggests that altered redox homeostasis and increased oxidative stress, primarily implicated in the pathogenesis of MS, are a trigger for activation of a brain stress response. Relevant to maintenance of redox homeostasis, integrated mechanisms controlled by vitagenes operate in brain in preserving neuronal survival during stressful conditions. Vitagenes encode for heat shock proteins (Hsp) Hsp32, Hsp70, the thioredoxin and the sirtuin protein systems. In the present study we assess stress response mechanisms in the CSF, plasma and lymphocytes of control patients compared to MS patients. We found that the levels of vitagenes Hsp72, Hsc70, HO-1, as well as oxidative stress markers carbonyls and hydroxynonenals were significantly higher in the blood and CSF of MS patients than in control patients. In addition, an increased expression of Trx and sirtuin 1, together with a decrease in the expression of TrxR were observed. Our data strongly support a pivotal role for redox homeostasis disruption in the pathogenesis of MS and, consistently with the notion that new therapies that prevent neurodegeneration through nonimmunomodulatory mechanisms can have a tremendous potential to work synergistically with current MS therapies, unravel important targets for new cytoprotective strategies

Efectos de Chaetophractus villosus (desmarest, 1804) "peludo" sobre cultivos implantados bajo diferentes sistemas de labranza en la región agrícola de la provincia de La Pampa

La adopción generalizada de la siembra directa (SO) produjo cambios en el ecosistema agrícola-ganadero: entre otros, la disminución o aumento de poblaciones de animales y plantas. En las últimas campañas se observó abundante presencia de peludos, Chaetophractus villosus (Desrnarest, 1804), en los cultivos implantados bajo SO. Estos mamíferos establecen sus madrigueras en lotes cultivados provocando daños, deformando el terreno y dificultando el tránsito de maquinarias. El objetivo de este trabajo fue comparar la abundancia de cuevas en diferentes sistemas de labranza ampliando la información existente sobre este mamífero en la zona semiárida pampeana central. Durante las campañas 2008/09 y 2009/1 O se realizaron muestreos de cuevas y relevamiento de daños sobre cultivos de Zea mays L., maíz, Helianthus annuus L., girasol, Glycine max L., soja y Sorghum bicolor (L.) Moench., sorgo, bajo SD y sobre Triticum aestivum L., trigo, en lotes implantados bajo SD, labranza convencional (LC) y vertical (LV) en establecimientos de la región centro-este de La Pampa. Se realizaron transectas registrándose número de madrigueras, dimensiones, nivel de uso, antigüedad y estimación de daños. Los muestreos se realizaron cada 30 días durante el ciclo de los cultivos. Se encuestó a productores afectados por la presencia de peludos. Los productores encuestados manifestaron que el peludo provoca disminución de rendimientos, afecta el paso de maquinarias y el tránsito de operarios debido a la presencia de cuevas que alteran la topografía. Bajo SD, el cultivo estival más afectado fue girasol, donde se encontraron 583 plantas volcadas por hectárea. La mayor densidad de cuevas se presentó en lotes implantados con cultivos de girasol y maíz. En trigo se determinó que bajo SD el peludo realiza cuevas y escarbadas durante todo el ciclo del cultivo, mientras que bajo LC y LV se observaron solo al final del ciclo, sin registro de ataque a plantas en ninguno de los tres sistemas. Se concluye que la SD permitió el aumento de la población de peludos, ya que sus cuevas no son destruidas. Deben desarrollarse métodos de control que limiten su acción sobre los cultivos y que al mismo tiempo permitan su preservación