Non-convex image reconstruction via Expectation Propagation

Tomographic image reconstruction can be mapped to a problem of finding solutions to a large system of linear equations which maximize a function that includes \textit{a priori} knowledge regarding features of typical images such as smoothness or sharpness. This maximization can be performed with standard local optimization tools when the function is concave, but it is generally intractable for realistic priors, which are non-concave. We introduce a new method to reconstruct images obtained from Radon projections by using Expectation Propagation, which allows us to reframe the problem from an Bayesian inference perspective. We show, by means of extensive simulations, that, compared to state-of-the-art algorithms for this task, Expectation Propagation paired with very simple but non log-concave priors, is often able to reconstruct images up to a smaller error while using a lower amount of information per pixel. We provide estimates for the critical rate of information per pixel above which recovery is error-free by means of simulations on ensembles of phantom and real images.Comment: 12 pages, 6 figure

The Catalytic and Non-catalytic Functions of the Brahma Chromatin-Remodeling Protein Collaborate to Fine-Tune Circadian Transcription in Drosophila.

Daily rhythms in gene expression play a critical role in the progression of circadian clocks, and are under regulation by transcription factor binding, histone modifications, RNA polymerase II (RNAPII) recruitment and elongation, and post-transcriptional mechanisms. Although previous studies have shown that clock-controlled genes exhibit rhythmic chromatin modifications, less is known about the functions performed by chromatin remodelers in animal clockwork. Here we have identified the Brahma (Brm) complex as a regulator of the Drosophila clock. In Drosophila, CLOCK (CLK) is the master transcriptional activator driving cyclical gene expression by participating in an auto-inhibitory feedback loop that involves stimulating the expression of the main negative regulators, period (per) and timeless (tim). BRM functions catalytically to increase nucleosome density at the promoters of per and tim, creating an overall restrictive chromatin landscape to limit transcriptional output during the active phase of cycling gene expression. In addition, the non-catalytic function of BRM regulates the level and binding of CLK to target promoters and maintains transient RNAPII stalling at the per promoter, likely by recruiting repressive and pausing factors. By disentangling its catalytic versus non-catalytic functions at the promoters of CLK target genes, we uncovered a multi-leveled mechanism in which BRM fine-tunes circadian transcription

Chromium doped copper vanadate photoanodes for water splitting

Solar hydrogen obtained from photoelectrochemical water splitting offers a versatile approach towards the substitution of fossil fuels by decentralized and sustainable resources, like water and sun. In the present study we have investigated the Chromium doped Copper Vanadate (Cr:Cu3V2O8) as a candidate photoanode for photoelectrochemical water splitting. We have synthetized this material through a simple aqueous precipitation reaction, which easily allows compositional modifications. We have studied the effect of extrinsic doping with substitutional atoms like Chromium on the optical and photoelectrochemical properties. The main limiting factor for performance is related to the high bulk recombination, which is partially overcome by 0.75 at.% Chromium doping, with a five-fold enhancement of the charge separation efficiency at 1.23 V vs RHE. Despite this remarkable milestone, significant further improvement is needed for the technological exploitation of this material

Distribution, Abundance, and Diversity Patterns of the Thermoacidophilic “Deep-Sea Hydrothermal Vent Euryarchaeota 2”

Cultivation-independent studies have shown that taxa belonging to the “deep-sea hydrothermal vent euryarchaeota 2” (DHVE2) lineage are widespread at deep-sea hydrothermal vents. While this lineage appears to be a common and important member of the microbial community at vent environments, relatively little is known about their overall distribution and phylogenetic diversity. In this study, we examined the distribution, relative abundance, co-occurrence patterns, and phylogenetic diversity of cultivable thermoacidophilic DHVE2 in deposits from globally distributed vent fields. Results of quantitative polymerase chain reaction assays with primers specific for the DHVE2 and Archaea demonstrate the ubiquity of the DHVE2 at deep-sea vents and suggest that they are significant members of the archaeal communities of established vent deposit communities. Local similarity analysis of pyrosequencing data revealed that the distribution of the DHVE2 was positively correlated with 10 other Euryarchaeota phylotypes and negatively correlated with mostly Crenarchaeota phylotypes. Targeted cultivation efforts resulted in the isolation of 12 axenic strains from six different vent fields, expanding the cultivable diversity of this lineage to vents along the East Pacific Rise and Mid-Atlantic Ridge. Eleven of these isolates shared greater than 97% 16S rRNA gene sequence similarity with one another and the only described isolate of the DHVE2, Aciduliprofundum boonei T469T. Sequencing and phylogenetic analysis of five protein-coding loci, atpA, EF-2, radA, rpoB, and secY, revealed clustering of isolates according to geographic region of isolation. Overall, this study increases our understanding of the distribution, abundance, and phylogenetic diversity of the DHVE2

El poder de la normalitat: sobre els joves i la llengua a Catalunya

Pràcticament tots els catalans, parlin castellà o català, si busquen entre els seus records, trobaran sense massa dificultat algun moment durant la seva infantesa, adolescència o primera joventut en el qual es van sorprendre de trobar un context lingüístic que els era desconegut o aliè. Per alguns va ser expressar-se en un entorn on el català era la llengua normal i viva; per a d'altres, trobar-se en un context en el qual el català era com qui diu una reserva índia; per a uns altres ser en una situació en la qual el català i el castellà s'alternaven amb gran naturalitat; i per a d'altres trobar canvis en el matís dels usos o en les connotacions i percepcions al voltant de la llengua

IL-4 drives microglia and macrophages toward a phenotype conducive for tissue repair and functional recovery after spinal cord injury

Macrophages and microglia play a key role in the maintenance of nervous system homeostasis. However, upon different challenges, they can adopt several phenotypes, which may lead to divergent effects on tissue repair. After spinal cord injury (SCI), microglia and macrophages show predominantly pro-inflammatory activation and contribute to tissue damage. However, the factors that hamper their conversion to an anti-inflammatory state after SCI, or to other protective phenotypes, are poorly understood. Here, we show that IL-4 protein levels are undetectable in the spinal cord after contusion injury, which likely favors microglia and macrophages to remain in a pro-inflammatory state. We also demonstrate that a single delayed intraspinal injection of IL-4, 48 hours after SCI, induces increased expression of M2 marker in microglia and macrophages. We also show that delayed injection of IL-4 leads to the appearance of resolution-phase macrophages, and that IL-4 enhances resolution of inflammation after SCI. Interestingly, we provide clear evidence that delayed administration of IL-4 markedly improves functional outcomes and reduces tissue damage after contusion injury. It is possible that these improvements are mediated by the presence of macrophages with M2 markers and resolution-phase macrophages. These data suggest that therapies aimed at increasing IL-4 levels could be valuable for the treatment of acute SCI, for which there are currently no effective treatments

Stability of 3D-porous Ni/Cu cathodes under real alkaline electrolyzer operating conditions and its effect on catalytic activity

Despite the development and synthesis of new electrode materials for hydrogen generation in alkaline water electrolyzers has been a research topic widely exploited in the last years, stability tests on the obtained cathodes have been restricted to long-term potentiostatic/galvanostatic experiments which do not fulfil the real operating conditions that take place in those devices. In this work, two different Service Life Tests have been designed and implemented, aiming at including particular conditions (i.e. inverse polarity and short-circuit) in the durability and catalytic activity of cathode characterization. For this purpose, Ni/Cu bilayered porous electrodes were prepared using different Ni electrodeposition times (15, 30 and 45 min) following a double template electrochemical method. It has been confirmed that the electrode with the lowest Ni content can be considered as a promising electrocatalyst for hydrogen production under industrial conditions because of its optimal activity and stability after the two sets of testing conditions. In particular, electrochemical studies demonstrated that an inversion in polarity can positively affect the electrode performance, as a consequence of the synergetic interaction between CuO/Cu(OH)(2) and beta-Ni(OH)(2) species formed at potentials below the oxygen evolution domain.The authors gratefully acknowledge financial support given by the Generalitat Valenciana (PROMETEO/2010/023) and Spanish Government (Ministerio de Ciencia e Innovation) for the postgraduate grants AP2007-01243 (Carlos Valero-Vidal) and AP2007-03737 (Isaac Herraiz-Cardona).Valero Vidal, C.; Herraiz Cardona, I.; Pérez-Herranz, V.; Igual Muñoz, AN. (2016). Stability of 3D-porous Ni/Cu cathodes under real alkaline electrolyzer operating conditions and its effect on catalytic activity. Applied Catalysis B: Environmental. 198:142-153. doi:10.1016/j.apcatb.2016.05.030S14215319

The relationship of large fire occurrence with drought and fire danger indices in the western USA, 1984–2008: the role of temporal scale

The relationship between large fire occurrence and drought has important implications for fire prediction under current and future climates. This study’s primary objective was to evaluate correlations between drought and fire-danger- rating indices representing short- and long-term drought, to determine which had the strongest relationships with large fire occurrence at the scale of the western United States during the years 1984-2008. We combined 4-8-km gridded drought and fire-danger-rating indices with information on fires greater than 404.7 ha (1000 acres). To account for differences in indices across climate and vegetation assemblages, indices were converted to percentile conditions for each pixel. Correlations between area burned and short-term indices Energy Release Component and monthly precipitation percentile were strong (R2=0.92 and 0.89), as were correlations between number of fires and these indices (R2=0.94 and 0.93). As the period of time tabulated by indices lengthened, correlations with fire occurrence weakened: Palmer Drought Severity Index and 24-month Standardised Precipitation Index percentile showed weak correlations with area burned (R2= 0.25 and -0.01) and number of large fires (R2=0.3 and 0.01). These results indicate associations between short-term indices and moisture content of dead fuels, the primary carriers of surface fire

Social Movement Gains and Losses : Dilemmas of Arena Creation

Social movements never entirely win or lose, nor do they suddenly appear or disappear. Just as their component parts recombine and continue in other forms, so movements have dozens of impacts of various kinds. To make sense of this complexity we propose examining the outcomes of political interactions for a variety of players (including individuals) across a range of arenas. Given the acknowledged tradeoffs and dilemmas of collective action, we would expect packages of outcomes to appear together sometimes; for example, gains in street mobilization may lead to losses in the form of a damaged reputation or police repression. The first step to explaining such patterns is to identify and name them. We examine one of these outcome patterns, the arena-ownership package, through the case of Seattle's historic $15 per hour wage law passed in 2014, the first ever in a major U.S. city. The players who crafted the bill included an avowed Socialist, the owner of Seattle's iconic Space Needle tower, many representatives of the city's labor movement, and the newly elected Democratic Mayor Ed Murray. These diverse players moved through a series of complex arenas to arrive at the legislative outcome. In this case, we find players who create new arenas, rather than only using already-existing arenas. This move is associated with a typical package of gains and losses: increased control for the player on the one hand, but corresponding losses and risks—the alienation of excluded players and increased perception of responsibility. The creating player is blamed for the arena's failures as well as credited with its successes.Peer reviewe