Graph analysis of functional brain networks: practical issues in translational neuroscience

The brain can be regarded as a network: a connected system where nodes, or units, represent different specialized regions and links, or connections, represent communication pathways. From a functional perspective communication is coded by temporal dependence between the activities of different brain areas. In the last decade, the abstract representation of the brain as a graph has allowed to visualize functional brain networks and describe their non-trivial topological properties in a compact and objective way. Nowadays, the use of graph analysis in translational neuroscience has become essential to quantify brain dysfunctions in terms of aberrant reconfiguration of functional brain networks. Despite its evident impact, graph analysis of functional brain networks is not a simple toolbox that can be blindly applied to brain signals. On the one hand, it requires a know-how of all the methodological steps of the processing pipeline that manipulates the input brain signals and extract the functional network properties. On the other hand, a knowledge of the neural phenomenon under study is required to perform physiological-relevant analysis. The aim of this review is to provide practical indications to make sense of brain network analysis and contrast counterproductive attitudes

Guidance in Business Intelligence & Analytics Systems: A Review and Research Agenda

While the data amount grows exponentially, the number of people with analytical and technical skills is only slowly increasing. This skill gap is putting pressure on the labor market and increasing the need for personnel with these skills. At the same time, companies are forced to think of alternative ways to empower their less-skilled workforce to take on Business Intelligence and Analytics (BI&A) tasks. One promising attempt to address these challenges may turn to the concept of guidance. However, the current body of research on guidance in BI&A systems is scattered and lacks a structured investigation from which future research avenues can be derived. To address this gap, this article analyzes five categories, namely BI&A phases, guidance degree, guidance generation, user roles, and interactivity form. Reviewing 82 articles, our contribution is to synopsize articles on guidance in BI&A systems and to suggest five research avenues

The space-time torsion in the context of the Exact Foldy-Wouthuysen Transformation for a Dirac fermion

In this work we focus our attention in the inconsistency that appears when the Semi-Exact Foldy-Wouthuysen transformation for the Dirac field interacting with space-time torsion field is performed. In order to solve this problem, we present a new involution operator that makes possible to perform the exact transformation when torsion field is present. Such operator has a structure, well known in the literature, composed of the product of an operator that acts in the matrices space and another one that acts in the function space. We also present the bound state of this theory and discuss the possible experimental analysis

Stability of bacteriophages in burn wound care products

Bacteriophages could be used along with burn wound care products to enhance antimicrobial pressure during treatment. However, some of the components of the topical antimicrobials that are traditionally used for the prevention and treatment of burn wound infection might affect the activity of phages. Therefore, it is imperative to determine the counteraction of therapeutic phage preparations by burn wound care products before application in patients. Five phages, representatives of two morphological families (Myoviridae and Podoviridae) and active against 3 common bacterial burn wound pathogens (Acinetobacter baumannii, Pseudomonas aeruginosa and Staphylococcus aureus) were tested against 13 different products commonly used in the treatment of burn wounds. The inactivation of the phages was quite variable for different phages and different products. Majority of the anti-infective products affected phage activity negatively either immediately or in the course of time, although impact was not always significant. Products with high acidity had the most adverse effect on phages. Our findings demonstrate that during combined treatment the choice of phages and wound care products must be carefully defined in advance

Geometric compression of invariant manifolds in neural nets

We study how neural networks compress uninformative input space in models where data lie in $d$ dimensions, but whose label only vary within a linear manifold of dimension $d_\parallel < d$. We show that for a one-hidden layer network initialized with infinitesimal weights (i.e. in the \textit{feature learning} regime) trained with gradient descent, the uninformative $d_\perp=d-d_\parallel$ space is compressed by a factor $\lambda\sim \sqrt{p}$, where $p$ is the size of the training set. We quantify the benefit of such a compression on the test error $\epsilon$. For large initialization of the weights (the \textit{lazy training} regime), no compression occurs and for regular boundaries separating labels we find that $\epsilon \sim p^{-\beta}$, with $\beta_\text{Lazy} = d / (3d-2)$. Compression improves the learning curves so that $\beta_\text{Feature} = (2d-1)/(3d-2)$ if $d_\parallel = 1$ and $\beta_\text{Feature} = (d + d_\perp/2)/(3d-2)$ if $d_\parallel > 1$. We test these predictions for a stripe model where boundaries are parallel interfaces ($d_\parallel=1$) as well as for a cylindrical boundary ($d_\parallel=2$). Next we show that compression shapes the Neural Tangent Kernel (NTK) evolution in time, so that its top eigenvectors become more informative and display a larger projection on the labels. Consequently, kernel learning with the frozen NTK at the end of training outperforms the initial NTK. We confirm these predictions both for a one-hidden layer FC network trained on the stripe model and for a 16-layers CNN trained on MNIST, for which we also find $\beta_\text{Feature}>\beta_\text{Lazy}$. The great similarities found in these two cases support that compression is central to the training of MNIST, and puts forward kernel-PCA on the evolving NTK as a useful diagnostic of compression in deep nets

Habitat Use of Ringed Seals (Phoca hispida) in the North Water Area (North Baffin Bay)

In conjunction with the International North Water Polynya Study in Smith Sound (northern Baffin Bay) in 1997-99, we examined the area use and diving activity of 23 ringed seals (Phoca hispida) that had been equipped with satellite transmitters on the Greenland side of the North Water (NOW) area. The study covered the period 12 August 1996-30 June 1999. Contact with the seals was maintained for an average of 108 days (range: 8-332 days). Four seals emigrated from the NOW area. During all seasons, the seals that remained in the area spent about 90% of the time in coastal (&lt; 100 m deep) waters in the eastern parts of the NOW area. The total area visited by the seals during the open-water season ranged between 10 300 km² (1996) and 18 500 km² (1998), corresponding to about 15% to 25% of the entire NOW area. In winter, the total area visited by the seals varied between 2500 km² (1996-97) and 7000 km² (1998-99), and in spring, between 800 km² (1999) and 2100 km² (1997). Individual movement was significantly greater during the open-water season than during winter and spring. Maximum dive depths recorded were over 500 m (maximum for the instrument) outside and 376 m inside the NOW, for a 96 kg male seal. Non-adult seals spent about 99% of the time in waters less than 100 m deep, and more than 92% of the time in the upper 50 m. In contrast, adults tended to spend more time at greater depths. The study indicated that (1) the ringed seals took advantage of the generally lighter ice conditions in the eastern NOW, and (2) that non-adults likely exploited ice-associated amphipods and young polar cod (Boreogadus saida), and adults, mainly older polar cod and cephalopods taken at greater depths.Conjointement avec l'étude internationale sur la polynie de l'Eau du Nord dans le détroit de Smith (partie nord de la baie de Baffin) menée de 1997 à 1999, on a examiné l'utilisation de cette zone et l'activité de plongée de 23 phoques annelés (Phoca hispida) munis d'émetteurs-satellite du côté groenlandais de la région de l'Eau du Nord («NOW»). L'étude a couvert la période allant du 12 août 1996 au 30 juin 1999. Le contact avec les phoques a été maintenu pendant une moyenne de 108 jours (étendue: 8-332 jours). Quatre phoques ont émigré de la zone NOW. Durant toutes les saisons, les phoques qui restaient dans la zone passaient environ 90% du temps dans des eaux côtières (profondeur &lt; 100 m) dans les secteurs orientaux de NOW. La superficie totale visitée par les phoques durant la saison d'eau libre allait de 10 300 km² (1996) à 18 500 km² (1998), correspondant à environ 15 à 25% de toute la zone NOW. En hiver, l'étendue totale fréquentée par les phoques allait de 2500 km² (1996-1997) à 7000 km² (1998-1999), et au printemps, de 800 km² (1999) à 2100 km² (1997). Les déplacements individuels étaient de beaucoup plus grands durant la saison d'eau libre qu'au cours de l'hiver et du printemps. Les profondeurs maximales de plongée enregistrées dépassaient 500 m (limite de l'instrument) à l'extérieur de la zone NOW et 376 m à l'intérieur, pour un phoque mâle de 96 kg. Les phoques non adultes passaient environ 99% du temps dans des eaux à une profondeur ne dépassant pas 100 m, et plus de 92% du temps dans les 50 m supérieurs. En revanche, les adultes avaient tendance à passer plus de temps à de plus grandes profondeurs. L'étude révèle 1) que les phoques annelés tiraient parti du fait qu'il y avait moins de glace dans la partie orientale de NOW, et 2) que, selon toute vraisemblance, les non-adultes exploitaient amphipodes et jeune morue polaire (Boreogadus saida) associés à la glace, les adultes se nourrissant surtout de morue polaire plus âgée et de céphalopodes prélevés à de plus grandes profondeurs