Geometry shapes propagation: Assessing the presence and absence of cortical symmetries through a computational model of cortical spreading depression

Cortical spreading depression (CSD), a depolarization wave which originates in the visual cortex and travels toward the frontal lobe, has been suggested to be one neural correlate of aura migraine. To the date, little is known about the mechanisms which can trigger or stop aura migraine. Here, to shed some light on this problem and, under the hypothesis that CSD might mediate aura migraine, we aim to study different aspects favoring or disfavoring the propagation of CSD. In particular, by using a computational neuronal model distributed throughout a realistic cortical mesh, we study the role that the geometry has in shaping CSD. Our results are two-fold: first, we found significant differences in the propagation traveling patterns of CSD, both intra and inter-hemispherically, revealing important asymmetries in the propagation profile. Second, we developed methods able to identify brain regions featuring a peculiar behavior during CSD propagation. Our study reveals dynamical aspects of CSD, which, if applied to subject-specific cortical geometry, might shed some light on how to differentiate between healthy subjects and those suffering migraine

Temporal excitation patterns on the cerebral cortex as a result of migraine modeling

The complex, highly individual, geometry of the cerebral cortex in humans presents a major challenge in studying the spreading of spontaneous neuronal activity. Recent computational advances [1] allow to simulate the propagation of depolarization waves on the macroscale and for individual geometries, reconstructed from accurate medical imaging as MRI, with high levels of detail. In this paper we take advantage of such technique to study the temporal excitation patterns that follow the passage of a depolarization wave on the cerebral cortex.This work was supported by the Bizkaia Talent and European Commission through COFUND under the grant BRAhMS – Brain Aura Mathematical Simulation– (AYD-000- 285), and also by the Basque Government through the BERC 2014-2017 program, and by the Spanish Ministry of Economics and Competitiveness MINECO: BCAM Severo Ochoa excellence accreditation SEV-2013-0323. JMC acknowledges financial support from Ikerbasque: The Basque Foundation for Science and Euskampus at UPV/EHU

Fish-based groups for ecological assessment in rivers: the importance of environmental drivers on taxonomic and functional traits of fish Assemblages

The use of river-types is of practical value, serving as groups for which assessment procedures can be developed and applied. An abiotic typology was set by the Portuguese Water Agency, mainly based on 6 major morphoclimatic regions. However, to be biologically meaningful, this typology should fit the distribution patterns of the biological quality elements communities proposed in Water Framework Directive under the lowest possible human pressure. This study aimed to identify and characterize fish-based geographical groups for continental Portugal and their environmental and geographical discriptors, using taxonomic and functional traits. Sampling took place between 2004 and 2006 during Spring. Fish fauna from 155 reference sites was analysed using a multivariate approach. Cluster Analysis on fish composition identified 10 fish-groups, expressing a clear correspondence to the river basin level, due to the restrict basin distribution of many species. Groups showed a wider aggregation in 4 regions with a larger geographical correspondence, statistically supported by Similarity Analysis, both on fish composition and mostly on fish metrics/guilds. Principal Components Analysis revealed major environmental drivers associated to fish-groups and fish-regions. Fish-groups were hierarchically grouped over major and local regions, expressing a large-scale response to a North-South environmental gradient defined by temperature, precipitation, mineralization and altitude, and a regional scale response mainly to drainage area and flow discharge. From North to South, fish-regions were related to the morphoclimatic regions. Results contributed to reduce redundance in abiotic river-types and set the final typology for Portuguese rivers, constituting a fundamental tool for planning and managing water resources

Bounds on Relativistic Deformed Kinematics from the Physics of the Universe Transparency

We analyze the kinematics of electron-positron production in a photon-photon interaction when one has a modification of the special relativistic kinematics as a power expansion in the inverse of a new high-energy scale. We derive the equation for the threshold energy of this reaction to first order in this expansion, including the effects due to a modification of the energy-momentum conservation equation. In contrast with the Lorentz invariance violation case, a scale of the order of a few TeV is found to be compatible with the observations of very high-energy cosmic gamma rays in the case of a modification compatible with the relativity principle

The organisation of fish assemblages in the regulated Lima basin, Northern Portugal

In order to understand the structure of fish assemblages in the modified Lima basin (Northern Portugal), two distinct datasets concerning the presence and abundance of fish species were subjected to multivariate analysis. On the River Lima two types of flow modification are present within kilometres of one another: (a) a reduced and constant flow due to hypolimnetic release; and (b) an intense and irregular flow. A comparison of their influence on fish assemblages revealed a gradient of assemblage types from tributaries to main river sites. The latter were characterised by a strong dominance of cyprinids, particularly Iberian barbel (Barbus bocagei). The former harboured two kinds of fish assemblages: those closer to the river mouth were dominated by the cyprinids Iberian chub (Squalius carolitertii) and Iberian nase (Chondrostoma polylepis), which were also frequently present in the main river; while in those further upstream the predominant species was the brown trout (Salmo trutta). Although explanatory variables such as distance from source, altitude, substrate coarseness and width were the primary correlates of fish assemblage composition, dam construction and flow regulation also had a significant effect upon assemblage structure, particularly by: i) reducing the importance of migratory species; ii) constraining the presence of trout in the regulated segments; and iii) simplifying the community, especially in the case of the constant and reduced flow regimeinfo:eu-repo/semantics/publishedVersio

Modeling Nonequilibrium Phase Transitions and Critical Behavior in Complex Systems

We comment on some recent, yet unpublished results concerning instabilities in complex systems and their applications. In particular, we briefly describe main observations during extensive computer simulations of two lattice nonequilibrium models. One exhibits robust and efficient processes of pattern recognition under synaptic coherent activity; the second example exhibits interesting critical behavior and simulates nucleation and spinodal decomposition processes in driven fluids.Comment: 6 pages, 4 figure

Patient-specific computational modeling of Cortical Spreading Depression via Diffusion Tensor Imaging

Cortical Spreading Depression (CSD), a depolarization wave originat- ing in the visual cortex and traveling towards the frontal lobe, is com- monly accepted as a correlate of migraine visual aura. As of today, little is known about the mechanisms that can trigger or stop such phenomenon. However, the complex and highly individual characteristics of the brain cortex suggest that the geometry might have a significant impact in sup- porting or contrasting the propagation of CSD. Accurate patient-specific computational models are fundamental to cope with the high variability in cortical geometries among individuals, but also with the conduction anisotropy induced in a given cortex by the complex neuronal organisa- tion in the grey matter. In this paper we integrate a distributed model for extracellular potassium concentration with patient-specific diffusivity tensors derived locally from Diffusion Tensor Imaging data.This work was supported by the Bizkaia Talent and European Commission through COFUND under the grant BRAhMS - Brain Aura Mathematical Sim- ulation (AYD-000-285), by the Basque Government through the BERC 2014- 2017 program, and by the Spanish Ministry of Economics and Competitiveness MINECO through the BCAM Severo Ochoa excellence accreditation SEV-2013- 0323 and the Spanish "Plan Estatal de Investigación, Desarrollo e Innovación Orientada a los Retos de la Sociedad" under Grant BELEMET - Brain ELEctro- METabolic modeling and numerical approximation (MTM2015-69992-R). JMC acknowledges financial support from Ikerbasque: The Basque Foundation for Science and Euskampus at UPV/EHU

Physics of the universe transparency in a deformed kinematics

We present a first study of the possible effects of a relativistic deformation of special relativity in the recent observations of very high-energy gamma rays by the LHAASO experiment, which has opened a new phenomenological window to study deformations in the kinematics of special relativity. Our analysis of the interaction of high-energy photons with the CMB background complements theoretical studies based on Lorentz invariance violation scenarios, while making predictions that would allow one to distinguish between a violation and a deformation of the symmetries of special relativity

A qualidade das bases de dados como factor crucial em estudos ambientais: condições de referência e tipologia com base piscícola para rios portugueses

Com base num conjunto superior a 1000 amostragens piscícolas em rios portugueses (troços vadeáveis) realizadas por diversas entidades nacionais nos últimos 10 anos, seleccionou-se um grupo de 459 locais que cumprem critérios de normalização de amostragem, procedimentos no terreno, e acuidade nas identificações taxonómicas. Estes locais representam a diversidade de condições naturais e de impactos humanos em Portugal Continental. Para caracterizar a magnitude e tipo de perturbação humana em cada local foram aplicadas 15 variáveis de pressão – ao nível do troço, segmento e bacia – classificadas de acordo com o desvio às condições naturais (de 1 para ausência de desvio, até 5 para forte degradação). Este passo envolveu um longo período de trabalho e baseou-se na análise de várias fontes de informação geográfica e documental, em inquéritos e no conhecimento do terreno. Durante as fases de selecção de locais e construção das bases de dados ambientais e biológicas, toda a informação foi sujeita a procedimentos de controle de qualidade de dados. É proposta uma metodologia para a selecção de sítios de referência; desta forma, foram incluídos neste grupo os locais com pontuação 1 ou 2 em, pelo menos, 80% das variáveis, permitindo a classificação 3 em 20% (três variáveis), excepto para a variável “abundância de indivíduos exóticos”, que obrigatoriamente correspondeu à pontuação 1 ou 2. Uma abordagem estatística multivariada suportou os dois passos seguintes: a definição da tipologia com base nas ictiocomunidades e a alocação de todos os locais num tipo. Utilizando os sítios de referência, e com base na classificação de grupos funcionais piscícolas, foram estabelecidos 6 tipos (t.): t. salmonícola da região norte; t. transição salmonícola-ciprinícola da região norte; t. ciprinícola de pequena dimensão das regiões norte interior e sul; t. ciprinícola de média dimensão da região norte; t. ciprinícola de média dimensão da região sul e t. ciprinícola da região norte litoral. A análise discriminante múltipla (ADM) suportou a tipologia piscícola, alocando correctamente 71 a 93% dos locais para os seis grupos; temperatura média em Julho, área de drenagem, altitude, precipitação média anual e uma variável categórica de enquadramento geográfico foram as variáveis retidas pelo modelo final. A ADM evidenciou elevada robustez ao classificar a maioria dos locais de não referência num dos tipos da respectiva região geográfica e ao detectar variações longitudinais das comunidades piscícolas ao longo de vários rios

Emerging Pharmacotherapies for Adult Patients with Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) treatment regimes are amongst the longest, most intensive and complex used in hematooncology. Despite this, while treatment of pediatric ALL is a success story, we are far from being able to ensure a durable response in adult ALL. This is not due to failure of induction therapy as a complete remission (CR) is achieved in over 90% of patients. However the challenge remains in ensuring a sustained remission. Furthermore in the face of relapsed disease, salvage therapies currently offer a poor chance of a good outcome. This article reviews the novel agents which show the most promise in the treatment of adult ALL