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The harmful microalgae Gymnodinium catenatum is a unique naked dinoflagellate that produces paralytic shellfish poisoning toxins (PSTs). This species is common along the coasts of the Mexican Pacific and is responsible for paralytic shellfish poisoning, which has resulted in notable financial losses in both fisheries and aquaculture. In the Gulf of California, G. catenatum has been related to mass mortality events in fish, shrimp, seabirds, and marine mammals. In this study, the growth, toxin profiles, and toxin content of four G. catenatum strains isolated from Bahía de La Paz (BAPAZ) and Bahía de Mazatlán (BAMAZ) were evaluated with different N:P ratios, keeping the phosphorus concentration constant. All strains were cultivated in semi-continuous cultures (200 mL, 21.0 °C, 120 µmol photon m−2s−1, and a 12:12 h light-dark cycle) with f/2 + Se medium using N:P ratios of: 4:1, 8:1, 16:1, 32:1, and 64:1. Paralytic toxins were analyzed by HPLC with fluorescence detection. Maximum cellular abundance and growth were obtained at an N:P ratio of 64:1 (3188 cells mL−1 and 0.34 div day−1) with the BAMAZ and BAPAZ strains. A total of ten saxitoxin analogs dominated by N-sulfocarbamoyl (60–90 mol%), decarbamoyl (10–20 mol%), and carbamoyl (5–10 mol%) toxins were detected. The different N:P ratios did not cause significant changes in the PST content or toxin profiles of the strains from both bays, although they did affect cell abundance. [ABSTRACT FROM AUTHOR]

The general objective of this research is to analyze the employment conditions in Venezuela as a result of COVID-19, for which a descriptive documentary research methodology was used, through an analytical technique. Applying the method of collecting secondary sources, the review of various documents, both printed and digital, was used; One of the main sources analyzed in this study can be highlighted as the State of Alarm Decree No. 4,160 (2020), in addition to the Constitution of the Bolivarian Republic of Venezuela (1999), the Penal Code (2000), the Organic Law on States of Exception (2000); and international documents published by the International Labor Organization (ILO). This methodology made it possible to establish the definition of unemployment and explain how this affects the population and the impact it has on companies, in turn it made it possible to state how the pandemic crisis caused by COVID-19 modified working conditions and explain strategies to maintain the optimum environment in the workplace. It can be concluded that the distancing and biosecurity measures have helped in a certain way to prevent the spread of COVID-19; but as a result of this, economic concerns have increased, making it necessary for the national government to adopt more measures that protect workers and companies, with social significance. [ABSTRACT FROM AUTHOR]

The objective of this article is to describe and analyze the strikes that led the wood officiants in the city of San José, in July 1918, in which the demand for the establishment of the eighthour workday was highlighted. The methodology proposed by Eric Hobsbawn and George Rudé was used to analyze the characteristics of the social movement, which have been adapted to perform a kind of "anatomy" of the strikes by using the following variables: 1) spatial and temporal distribution of the strike, 2) conflict agenda, 3) social composition of the movement, 4) organization methods and leadership pattern, 5) employers' attitude and a balance of the social movement. The strikes of July 1918 were the first social movement in the history of Costa Rica where they fought for the 8-hour workday. In spite of not reaching this demand at the time, they placed, for the first time, in the arena of the social conflict and the social agenda the eight-hour workday as workers' rights. [ABSTRACT FROM AUTHOR]

Coded orthogonal frequency-division multiplexing (COFDM) is a popular modulation technique for wireless communication that guarantees reliable transmission of data over noisy wireless channels. However, a major disadvantage in implementing it is its resulting high peak to average power ratio (PAPR). Including forward error correction (FEC) in the orthogonal frequency division multiplexing (OFDM) system enables the avoidance of transmission errors. Nevertheless, the selected code may impact the value of PAPR. The objective of this paper is to analyze the impact of FEC on the PAPR for the COFDM system based on the autocorrelation of the signal, before the inverse fast Fourier transform (IFFT) block in the COFDM system, the evaluation of the complementary cumulative distribution function (CCDF) of PAPR, and the bit error rate (BER). The autocorrelation of the COFDM system is calculated based on a Markov chain model. From the results, we can reach a conclusion on the characteristics we need to consider in order to choose the codes relating to the PAPR performance in the COFDM system. [ABSTRACT FROM AUTHOR]

An abundant and diverse assemblage of decapod crustaceans from the Neogene (Miocene to Pliocene) from the Las Perdices and Tubará formations in San Jacinto Fold Belt (Colombian Caribbean) is here reported. Found in shallow marine and paralic sediments, specimens of the following species are identified: Callianassidae, Neocallichirus scotti (Brown and Pilsbry, 1913), Glypturus toulai (Rathbun, 1919), Petrochirus bouvieri Rathbun, 1919, Hepatus lineatinus Collins and Todd in Todd and Collins, 2005, Palaeopinixa perornata Collins and Morris, 1976, Persephona enigmatica Collins and Todd in Todd and Collins, 2005, Microphrys sp., Necronectes proavitus (Rathbun, 1918), Scylla sp., Euphylax maculatus Collins and Todd in Todd and Collins, 2005, and Eurytium sp. All of these species indicate a correlation with other Caribbean crustaceans from the Neogene, mainly of Panama, Costa Rica, and Venezuela. The facies association and decapod assemblage suggest shallow marine environments for the Neogene units of this area of Caribbean coast of Colombia [ABSTRACT FROM AUTHOR]

En el presente artículo abordamos el tema de la adopción de la justicia restaurativa como ideología de administración e impartición de justicia en el Estado mexicano, a través de la Constitución federal y sus diversas normativas locales y nacionales. Lo anterior nos arroja ideas claras de los cambios sustanciales que debemos realizar y de cómo adecuar y armonizar nuestro marco normativo para abrir las puertas a tan prometedor sistema de impartición de justicia. [ABSTRACT FROM AUTHOR]

Background: The chronic obstructive lung disease (COPD) is a common, expensive and preventable disease, and the evaluation of the quality of life in patients with the condition widens the scope of the results in their attention. The objective was to evaluate the health related quality of life (HRQL) according to the severity of the COPD. Methods: Descriptive study. Patients with COPD diagnosis according with the severity and related with the HRQL measured using a specific questionnaire. Statistical analyses were made using %2 or ANOVA in ranks according with the variables. A p value < 0.05 was considered significant. Results: 62 patients were included; 61% women. HRQL questionnaire showed the Activity dimension as the more negatively affected (65 ± 24 points, p < 0.05). In the Impact dimension, severity groups III and IV were more affected compared with groups I and II (p < 0.05). There was a directly correlation between a better FEV1 with better HRQL results (r2-0.544p< 0.0001). Conclusions: HRQL is affected and clinically meaningful in patients with a major severity degree of the COPD condition. The parameters that better predicts a worst HRQL was % FEV1 and FVC. [ABSTRACT FROM AUTHOR]

FMN hydrolases catalyze dephosphorylation of FMN to riboflavin. Although these enzymes have been described in many organisms, few had their corresponding genes cloned and their recombinant proteins biochemically characterized, and none had their physiological roles determined. We found previously that FMN hydrolase activity in pea chloroplasts is Mg2+-dependent, suggesting an enzyme of the haloacid dehalogenase (HAD) superfamily. In this study, a new FMN hydrolase was purified by multistep chromatography after ammonium sulfate precipitation. The molecular weight of the native protein was estimated at ~59,400, a dimer of about twice the predicted molecular weight of most HAD superfamily phosphatases. After SDS-PAGE of the partially purified material, two separate protein bands within 25-30 kDa were extracted from the gel and analyzed by nanoLC-MS/MS. Peptide sequence matching to the protein samples suggested the presence of three HAD-like hydrolases. cDNAs for sequence homologs from Arabidopsis thaliana of these proteins were expressed in Escherichia coli. Activity screening of the encoded proteins showed that the At1g79790 gene encodes an FMN hydrolase (AtcpFHy1). Plastid localization of AtcpFHy1 was confirmed using fluorescence microscopy of A. thaliana protoplasts transiently expressing the N-terminal fusion of AtcpFHy1 to enhanced green fluorescent protein. Phosphatase activity of AtcpFHy1 is FMN-specific, as assayed with 19 potential substrates. Kinetic parameters and pH and temperature optima for AtcpFHy1 were determined. A phylogenetic analysis of putative phosphatases of the HAD superfamily suggested distinct evolutionary origins for the plastid AtcpFHy1 and the cytosolic FMN hydrolase characterized previously. [ABSTRACT FROM AUTHOR]

Background. Because bacterial pathogens are the primary cause of travelers' diarrhea (TD), antibiotic prophylaxis is effective in TD prevention. This study assessed the efficacy and safety of the nonsystemic antibiotic rifaximin in preventing TD in US travelers to Mexico. Methods. Healthy adult students traveling to Mexico received rifaximin 600 mg/d or placebo for 14 days and were followed for 7 days post-treatment. Stool pattern and gastrointestinal symptoms were recorded in daily diary entries. The primary end point was prevention of TD during 14 days of treatment measured by time to first unformed stool. Results. A total of 210 individuals received rifaximin ( n = 106) or placebo ( n = 104) and were included in the safety population. Median age was 21 years (range, 18–75 y), and the majority of participants were female (65%). Efficacy analyses were conducted in a modified intent-to-treat population of 201 patients who received rifaximin ( n = 99) or placebo ( n = 102). Rifaximin prophylaxis reduced risk of developing TD versus placebo ( p < 0.0001). A smaller percentage of individuals who received rifaximin versus placebo developed all-cause TD (20% vs 48%, respectively; p < 0.0001) or TD requiring antibiotic therapy (14% vs 32%, respectively; p = 0.003). More individuals in the rifaximin group (76%) completed treatment without developing TD versus those in the placebo group (51%; p = 0.0004). Rifaximin provided a 58% protection rate against TD and was associated with fewer adverse events than placebo. Conclusions. Prophylactic treatment with rifaximin 600 mg/d for 14 days safely and effectively reduced the risk of developing TD in US travelers to Mexico. Rifaximin chemoprevention should be considered for TD in appropriate individuals traveling to high-risk regions. [ABSTRACT FROM AUTHOR]

Abstract: We studied the effects of combination treatment with an anti-inflammatory agent, interferon (IFN)-β, and a putative neuroprotective agent, an estrogen receptor (ER)-β ligand, during EAE. Combination treatment significantly attenuated EAE disease severity, preserved axonal densities in spinal cord, and reduced CNS inflammation. Combining ERβ treatment with IFNβ reduced IL-17, while it abrogated IFNβ-mediated increases in Th1 and Th2 cytokines from splenocytes. Additionally, combination treatment reduced VLA-4 expression on CD4+ T cells, while it abrogated IFNβ-mediated decreases in MMP-9. Our data demonstrate that combination treatments can result in complex effects that could not have been predicted based on monotherapy data alone. [Copyright &y& Elsevier]

FAD synthetases (EC 2.7.7.2) catalyze biosynthesis of FAD from FMN and ATP. Monofunctional FAD synthetases are known to exist in mammals and yeast; bifunctional enzymes also catalyzing phosphorylation of riboflavin to FMN are known to exist in bacteria. Previously known eukaryotic enzymes with FAD synthetase activity have no sequence similarity to prokaryotic enzymes with riboflavin kinase and FAD synthetase activities. Proteins homologous to bacterial bifunctional FAD synthetases, yet shorter and lacking amino acid motifs at the C terminus, were found by bioinformatic analyses in vascular plant genomes, suggesting that plants contain a type of FAD synthetase previously known to exist only in prokaryotes. The Arabidopsis thaliana genome encodes two of such proteins. Both proteins, which we named AtRibF1 and AtRibF2, carry N-terminal extensions with characteristics of organellar targeting peptides. AtRibF1 and AtRibF2 cDNAs were cloned by reverse transcription-PCR. Only FAD synthetase activity was detected in the recombinant enzymes produced in Escherichia coli. FMN and ATP inhibited both enzymes. Kinetic parameters of AtRibF1 and AtRibF2 for the two substrates were similar. Confocal microscopy of protoplasts transformed with enhanced green fluorescence protein-fused proteins showed that AtRibF1 and AtRibF2 are targeted to plastids. In agreement with subcellular localization to plastids, Percoll-isolated chloroplasts from pea (Pisum sativum) synthesized FAD from imported riboflavin. Riboflavin kinase, FMN hydrolase, and FAD pyrophosphatase activities were detected in Percoll-isolated chloroplasts and mitochondria from pea. We propose from these new findings a model for subcellular distribution of enzymes that synthesize and hydrolyze flavin nucleotides in plants. [ABSTRACT FROM AUTHOR]

Riboflavin kinases catalyze synthesis of FMN from riboflavin and ATP. These enzymes have to date been cloned from bacteria, yeast, and mammals, but not from plants. Bioinformatic approaches suggested that diverse plant species, including many angiosperms, two gymnosperms, a moss (Physcomitrella patens), and a unicellular green alga (Chlamydomonas reinhardtii), encode proteins that are homologous to riboflavin kinases of yeast and mammals, but contain an N-terminal domain that belongs to the haloacid dehalogenase superfamily of enzymes. The Arabidopsis homolog of these proteins was cloned by RT-PCR, and was shown to have riboflavin kinase and FMN hydrolase activities by characterizing the recombinant enzyme produced in Escherichia coli Both activities of the purified recombinant Arabidopsis enzyme (AtFMN/FHy) increased when the enzyme assays contained 0.02% Tween 20. The FMN hydrolase activity of AtFMN/FHy greatly decreased when EDTA replaced Mg2+ in the assays, as expected for a member of the Mg2+-dependent haloacid dehalogenase family. The functional overexpression of the individual domains in E. coli establishes that the riboflavin kinase and FMN hydrolase activities reside, respectively, in the C-terminal (AtFMN) and N-terminal (AtFHy) domains of AtFMN/FHy. Biochemical characterization of AtFMN/FHy, AtFMN, and AtFHy shows that the riboflavin kinase and FMN hydrolase domains of AtFMN/FHy can be physically separated, with little change in their kinetic properties. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we propose a new method to characterise a curve by means of the hierarchical computation of a multiresolution structure. This structure, consisting of successive lower resolution versions of the same object, is processed using the linked pyramid approach. We adapt the multiresolution pixel linking algorithm to the processing of curve contours which are described by their chain-code. We also introduce a selective class selection process which allows application of the algorithm to segmentation and detection of contour features. The resulting framework presents good performance for a wide range of object sizes without the need of any parameter tweaking, and allows detection of shape detail at different scales. [Copyright &y& Elsevier]

A synthesis of WOCE (and other) hydrographic data shows that the deep western boundary current of Antarctic Bottom Water has a double-core structure, and that it is differentially modified during its northward transit through the Brazil Basin. At 25°S, it descends about 200 m while continuing equatorward as a paired, double-core current over the relatively broad, sloping topography of the western region. The downslope core is faster, 4–6 cm s-1 versus 3 cm s-1, and is coincident with the high-density core. Equatorward of 19°S the cores begin to diverge and by 15°S, the velocity cores have separated and the high-speed pattern has inverted. Between 13° and 11°S the colder, slower-flowing branch (around 3 cm s-1) deepens by 350 m, with a noticeable decrease in the vertical stratification of overlying water characteristics. Subsequently, it continues to the equator toward the Romanche–Chain Fracture Zones. The warmer, faster-flowing branch (around 8 cm s-1) proceeds to the equator along the continental slope, eventually becoming the flow entering the equatorial channel. [ABSTRACT FROM AUTHOR]

The anomuran crabs are important from the biogeographic perspective because of their benthonic behavior in their adult state. For this reason, the present work summarizes the different studies developed to date on these crustaceans within the Gulf of California and reinforces the separation of the zone from others in the Province of Cortéz, or Cortesiana. The Gulf of California is inhibited by seventy-eight species of anomurans, belonging to seven families and twenty-eight genera. The best represented family regarding the number of genera (eleven), species (forty-five) and endemic species (eleven) is the Porcellanidae, followed by the Diogenidae with eight genera, fifteen species and four endemic species. The Gulf of California species are distributed in three large zoogeographical groups in the Eastern Pacific, the main one being the Panamic with an intrusion to the Gulf of 69.23% of the species reported. A second important group is that of the endemic species of the Gulf, with 24.35% of the existing species. The boreal species group with intrusion to the Gulf is present with 6.41%. Within the Californian Gulf, ten different zoogeographical groups are found, which demonstrate the great complexity of anomuran distribution, a product of the evolutionary history of this interior sea. [ABSTRACT FROM AUTHOR]

Paralytic shellfish toxin (PST) content in the dinoflagellate Gymnodinium catenatum changes with culture age, with a higher toxin concentration in the logarithmic phase that decreases when the culture ages. The gene copy number (GCN) of domains sxtA1 and sxtA4 was higher in the lag and stationary phase, and lag phase, respectively. No relationship was found between the GCN of the domains sxtA4 and sxtA1 with the PST content in G. catenatum. [Display omitted] • The paralytic shellfish toxins (PST) content does not have significant change with the growth phases. • The copy number of the domains sxtA1 and sxtA4 changes with the growth phase. • There is not correlation between PST content and sxtA gene copies. [ABSTRACT FROM AUTHOR]

Background: White matter hyperintensities (WMH) that occur in the setting of vascular cognitive impairment and dementia (VCID) may be dynamic increasing or decreasing volumes or stable over time. Quantifying such changes may prove useful as a biomarker for clinical trials designed to address vascular cognitive-impairment and dementia and Alzheimer's Disease. Objective: Conducting multi-site cross-site inter-rater and test-retest reliability of the MarkVCID white matter hyperintensity growth and regression protocol. Methods: The NINDS-supported MarkVCID Consortium evaluated a neuroimaging biomarker developed to track WMH change. Test-retest and cross-site inter-rater reliability of the protocol were assessed. Cognitive test scores were analyzed in relation to WMH changes to explore its construct validity. Results: ICC values for test-retest reliability of WMH growth and regression were 0.969 and 0.937 respectively, while for cross-site inter-rater ICC values for WMH growth and regression were 0.995 and 0.990 respectively. Word list long-delay free-recall was negatively associated with WMH growth (p < 0.028) but was not associated with WMH regression. Conclusions: The present data demonstrate robust ICC validity of a WMH growth/regression protocol over a one-year period as measured by cross-site inter-rater and test-retest reliability. These data suggest that this approach may serve an important role in clinical trials of disease-modifying agents for VCID that may preferentially affect WMH growth, stability, or regression. [ABSTRACT FROM AUTHOR]

The Maastrictian echinoid species Hardouninia mortonis (Michelin, 1850) typical from Upper Cretaceous deposits along the Gulf and Atlantic Coastal plains of USA and Canada, is here reported for the first time for Mexico into a peculiar matrix, which consists of a K/Pg reworked tsunamite deposited during an early Paleocene storm event in the NW portion of the Parras Basin, Difunta Group, NE Mexico. Our specimens have a peculiar small size compared with those reported for Maastrichtian localities in Mississippi amd North Carolina. Small-sized specimens are abundant in late Maastrichtian Las Encinas Formation of the Parras Basin, and are identical to the more than 50 specimens found included in reworked K/Pg tsunamite at Arroyo Amargos, Coahuila. Our interpretation is that the tsunamite was reworked during an early Paleocene storm, forming a channel-like structure of microconglomeratic sandstone, which includes ammonites (Sphenodiscus pleurisepta), the small Hardouinia mortonis , and delicate early Paleocene ostreoids. Other localities with reworked K/Pg tsunamite deposits are found in the adjacent La Popa Basin, interpreted also as deposited by early Paleocene storms in this area of NE Mexico, in Coahuila and Nuevo León states, but mix of Maastrichtian and Paleocene invertebrates has only been observed in Amargos. • Cretaceous echinoids embedded into reworked K/Pg tsunamite. • First record of mixed Cretaceous and Paleocene invertebrates in tsunamite. • High diversity of echinoid species in the Digunta Group, NE Mexico. • Extension of paleogeographic range of an echinoid species from the USA Gulf and Atlantic. [ABSTRACT FROM AUTHOR]

In September and November 2016, eight marine sampling sites along the coast of the southeastern Gulf of Mexico were monitored for the presence of lipophilic and hydrophilic toxins. Water temperature, salinity, hydrogen potential, dissolved oxygen saturation, inorganic nutrients and phytoplankton abundance were also determined. Two samples filtered through glass fiber filters were used for the extraction and analysis of paralytic shellfish toxins (PSTs) by lateral flow immunochromatography (IFL), HPLC with post-column oxidation and fluorescent detection (FLD) and UHPLC coupled to tandem mass spectrometry (UHPLC-MS/MS). Elevated nutrient contents were associated with the sites of rainwater discharge or those near anthropogenic activities. A predominance of the dinoflagellate Pyrodinium bahamense was found with abundances of up to 104 cells L−1. Identification of the dinoflagellate was corroborated by light and scanning electron microscopy. Samples for toxins were positive by IFL, and the analogs NeoSTX and STX were identified and quantified by HPLC-FLD and UHPLC-MS/MS, with a total PST concentration of 6.5 pg cell−1. This study is the first report that confirms the presence of PSTs in P. bahamense in Mexican waters of the Gulf of Mexico. [ABSTRACT FROM AUTHOR]

Allelopathy between phytoplankton organisms is promoted by substances released into the marine environment that limit the presence of the dominating species. We evaluated the allelopathic effects and response of cell-free media of Chattonella marina var. marina and Gymnodinium impudicum in the toxic dinoflagellate Gymnodinium catenatum. Additionally, single- and four-cell chains of G. catenatum isolated from media with allelochemicals were cultured to evaluate the effects of post exposure on growth and cell viability. Cell diagnosis showed growth limitation and an increase in cell volume, which reduced mobility and led to cell lysis. When G. catenatum was exposed to cell-free media of C. marina and G. impudicum, temporary cysts and an increased concentration of paralytic shellfish toxins were observed. After exposure to allelochemicals, the toxin profile of G. catenatum cells in the allelopathy experiments was composed of gonyautoxins 2/3 (GTX2/3), decarcarbamoyl (dcSTX, dcGTX2/3), and the sulfocarbamoyl toxins (B1 and C1/2). A difference in toxicity (pg STXeq cell−1) was observed between G. catenatum cells in the control and those exposed to the filtrates of C. marina var. marina and G. impudicum. Single cells of G. catenatum had a lower growth rate, whereas chain-forming cells had a higher growth rate. We suggest that a low number of G. catenatum cells can survive the allelopathic effect. We hypothesize that the survival strategy of G. catenatum is migration through the chemical cloud, encystment, and increased toxicity. [ABSTRACT FROM AUTHOR]

The effects of temperature on growth, cell toxicity, toxin content, and profile of paralytic shellfish toxins was determined in eight isolates of Gymnodinium catenatum from several localities along the Pacific Coast of Mexico. The isolates were cultivated in modified f/2 media with Se (10 −8 M), and a reduced concentration of Cu (10 −8 M), under a 12 h:12 h day–night cycle with an irradiance of 150 μE m −2 s −1 . Isolates were progressively adapted for three generations to each of the temperatures (16, 19, 22, 24, 27, 30, and 33 °C). The cultures were grown in 125 mL Erlenmeyer flasks with 60 mL of media and harvested by filtration in late exponential growth. Toxins were analyzed by HPLC with a post-column oxidation and fluorescent detection (FLD). G. catenatum isolates tolerate temperatures between 16 and 33 °C, with maximum growth rates of 0.32 and 0.39 div day −1 at 21 °C and 24 °C, respectively; maximum cell densities of 4700 and 5500 cells mL −1 were obtained at 27 and 21 °C, respectively. No effect of toxicity per cell with temperature was observed, varying between 10.10 and 28.19 pgSXTeq cell −1 . Ten saxitoxin analogues were detected in all isolates, observing changes in the toxin profile with temperature. C1/2 toxins decreased from 80% mol at 16 °C to 20% mol at 33 °C, B1/2 toxins increased from 19% mol at 16 °C to 42% mol at 33 °C, and decarbamoyl toxins were more abundant at 21 °C. These results show that G. catenatum isolates from different regions of the Pacific coast of Mexico have a similar response to temperature and that this parameter can modify growth rate, cell density, and toxin profile of the species, particularly the decarbamoyl and sulfocarbamoyl toxins. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV) has a worldwide distribution and is considered one of the most pathogenic and devastating viruses to the shrimp industry. A few studies have explored the effect of WSSV on shrimp acclimated to low (5 practical salinity units [psu]) or high (>40 psu) salinity conditions. In this work, we analysed the physiological response of WSSV-infected Litopenaeus vannamei juveniles that were acclimated to different salinities (5, 15, 28, 34 and 54 psu). We evaluated the osmotic response and survival of the shrimp at different times after infection (0 to 48 hours), and we followed the expression levels of a viral gene ( vp664) in shrimp haemolymph using real-time PCR. Our results indicate that the susceptibility of the shrimp to the virus increased at extreme salinities (5 and 54 psu), with higher survival rates at 15 and 28 psu, which were closer to the iso-osmotic point (24.7 psu, 727.5 mOsmol/kg). Acute exposure to the virus made the haemolymph less hyperosmotic at 5 and 15 psu and less hypo-osmotic at higher salinities (>28 psu). The capacity of white shrimp to osmoregulate, and thus survive, significantly decreased following WSSV infection. According to our results, extreme salinities (5 or 54 psu) are more harmful than seawater. [ABSTRACT FROM AUTHOR]

Abstract: An algorithm for estimating time-varying parameters of dynamical systems is proposed, within the large family of prediction error methods. The algorithm is based on the ability of Hopfield neural networks to solve optimisation problems, since its formulation can be summarized as minimisation of the prediction error by means of a continuous Hopfield network. In previous work, it was proved, under mild assumptions, that the estimates converge towards the actual values of parameters and the estimation error remains asymptotically bounded in the presence of measurement noise. The novelty of this work is the advance in the robustness analysis, by considering deterministic disturbances, which do not fulfil the usual statistical hypothesis such as normality and uncorrelatedness. A model of HIV epidemics in Cuba is used as suitable benchmark, which is confirmed by the computation of the sensitivity matrix. The results show a promising performance, in comparison to the conventional Least Squares Estimator. Indeed, the estimation error is almost always lower in the proposed method that in least squares, and it is never significantly higher. Further, from a qualitative point of view, the estimate provided by the Hopfield estimator is smoother, with no overshoot that could eventually destabilize a closed control loop. A significant finding is the fact that the form of the perturbation affects critically the dynamical behaviour and magnitude of the estimation, since the estimation error asymptotically vanishes when the disturbances are additive, but not when they are multiplicative. To summarize, we can conclude that the proposed estimator is an efficient and robust method to estimate time-varying parameters of dynamical systems. [Copyright &y& Elsevier]

Abstract: This work aims at a reflection on the evolution of the field of Neurocomputing along the last 20 years that have witnessed the sequence of editions of the International Work-Conference on Artificial Neural Networks (IWANN). This reflection arises inextricably of the evolution of connectionist networks themselves, describing their features and most remarkable particularities, most of which have prevailed in time. Another trend that is worth mentioning is the development of a strong interconnection with other paradigms comprised under the so-called Computational Intelligence, which can be understood as a set of nature-inspired computational methodologies and approaches to address complex real-world problems, which traditional approaches are ineffective or unfeasible to deal with. Indeed, many hybrid computational intelligence schemes have been developed that efficiently combine procedures from the domains of artificial neural networks, machine learning, evolutionary computation and fuzzy logic to be applied in complex domains. Finally, a brief description of the diverse contributions that have been included in this special issue is presented. These papers stem from previous versions presented at IWANN2011. [Copyright &y& Elsevier]

This study addressed the relative contribution of sexual and asexual reproduction to the genetic composition of populations of two scleractinian corals, Pocillopora damicornis and Porites panamensis, off the west coast of mainland Mexico. Reproductive indexes showed that P. damicornis reproduced both sexually and asexually; P. panamensis reproduced sexually, but colonies with an asexual origin were also observed (10-30%). Asexual reproduction is usually attributed to fragmentation caused by hurricanes; however, no significant association between reproductive index values and frequency of hurricanes was observed for either species. Environmental conditions in the Gulf of California seem to be more favorable for sexual reproduction in both species than other parts of the west coast of Mexico. This study contributes baseline information of differences in sexual and asexual reproduction in massive and branching corals [ABSTRACT FROM AUTHOR]

Highlights: [•] Three recombinant SHMTs from A. thaliana (AtSHMTs) were characterized. [•] Two enzymes faster at higher enzyme concentrations with monoglutamate folates. [•] The effect absent in the presence of pentaglutamate folate substrates. [•] No evidence for a change in the oligomerization state. [ABSTRACT FROM AUTHOR]

Genetic connectivity was studied in two scleractinian corals, Pocillopora damicornis ( branching and broadcast spawner) and Porites panamensis (massive and brooding type), along the Pacific coast of Mexico. Allelic diversity between adults and juveniles, the latter recruited after the El Niño - Southern Oscillation (ENSO) 1997 - 1998 event, was determined, and level of genetic connectivity among populations was assessed. There were no significant differences in allelic diversity between adults and juveniles from the same location. Seascape spatial genetic analysis suggested two or three clusters, depending on the species: (1) Bahías de Huatulco, (2) south of the Baja California Peninsula and Bahía de Banderas, and (3) locations in the Gulf of California. The most important barrier to gene flow was detected between Bahía de Banderas and Bahías de Huatulco and corresponds with a major coastal stretch of sandy beaches and lagoons. Moderate to high gene flow was found inside and at the entrance of the Gulf of California ( Nem = 62 - 250), possibly favored by seasonal circulation patterns and sexual reproduction. In contrast, low gene flow was observed between southern populations and the rest of coastal Mexico ( Nem < 1.7) based on high local recruitment and habitat discontinuity. A close genetic relationship of corals from the southern part of the Baja California Peninsula and severely damaged Bahía de Banderas coral communities confirmed that exchange of propagules could have taken place between the localities after the ENSO 1997 - 1998 event. Despite different reproductive strategies, both species showed similar patterns, suggesting the importance of surficial currents and habitat discontinuity to predict connectivity among coral reefs. [ABSTRACT FROM AUTHOR]

Dictyopteris prolifera, a marine algae (Phaeophyceae) native to Asian waters (Japan), has been collected recently on the western coast of the Baja California Peninsula, Mexico. Its finding represents the first record of this non-indigenous species on the Mexican Pacific coast, which also means a new record for American waters. Dictyopteris prolifera was found in June and September 2010, growing attached to rocks in the intertidal zone at Punta Morro Redondo, Cedros Island in Baja California, Mexico. Direct observations in the field about its abundance and size showed that D. prolifera has established as a permanent species. The mean length of specimens of this population is ~25 cm. Results of a monitoring programme show an increasing record of non-indigenous species on the coast of Baja California, mainly derived from ship traffic. [ABSTRACT FROM AUTHOR]

In this letter, the ability of higher-order Hopfield networks to solve combinatorial optimization problems is assessed by means of a rigorous analysis of their properties. The stability of the continuous network is almost completely clarified: (1) hyperbolic interior equilibria, which are unfeasible, are unstable; (2) the state cannot escape from the unitary hypercube; and (3) a Lyapunov function exists. Numerical methods used to implement the continuous equation on a computer should be designed with the aim of preserving these favorable properties. The case of nonhyperbolic fixed points, which occur when the Hessian of the target function is the null matrix, requires further study. We prove that these nonhyperbolic interior fixed points are unstable in networks with three neurons and order two. The conjecture that interior equilibria are unstable in the general case is left open. [ABSTRACT FROM AUTHOR]

Abstract: The Princeton Ocean Model (POM), as implemented for the Japan (East) Sea (JES) with mesoscale-admitting resolution is driven by seasonal throughflow and synoptic atmospheric forcing for 1999 through 2001. Temperature and salinity profiles from shipborne and PALACE float CTDs, and horizontal velocities at 800m from PALACE float trajectories, plus horizontal velocities at 15m from WOCE surface drifters for 1988 through 2001, are used to assess the performance of the numerical simulations for a base case. General agreement exists in the circulation at 15 and 800m and the horizontal and vertical structure of the upper ocean temperature and salinity fields. The mean observed flow at 15m defines the two branches of the Tsushima Warm Current and hints at the existence of a large cyclonic gyre over the Japan Basin, which the simulations also produce. The mean observed flow at 800m defines a large cyclonic recirculation gyre over the Japan Basin that validates the simulated flow pattern. Variances of the observed and simulated flows at 15 and 800m have similar patterns. The main discrepancies are associated with the strength of the seasonal thermocline and halocline and the location of the Subpolar Front. When smoother topography and smaller lateral friction are used in other cases, the thermocline and halocline strengthen, agreeing better with the observed values, and when 80% of total outflow transport is forced to exit through Soya Strait, the Subpolar Front extends along the coast to the north of Tsugaru Strait, which is an observed feature absent in the base case. [Copyright &y& Elsevier]

In this work, a novel method for on-line identification of non-linear systems is proposed based upon the optimisation methodology with Hopfield neural networks. The original Hopfield model is adapted so that the weights of the resulting network are time-varying. A rigorous analytical study proves that, under mild assumptions, the estimations provided by the method converge to the actual parameter values in the case of constant parameters, or to a bounded neighbourhood of the parameters when these are time-varying. Time-varying parameters, often appearing in mechanical systems, are dealt with by the neural estimator in a more natural way than by least squares techniques. Both sudden and slow continuous variations are considered. Besides, in contrast to the gradient method, the neural estimator does not critically depend on the adjustment of the gain. The proposed method is applied to the identification of a robotic system with a flexible link. A reduced output prediction error and an accurate estimation of parameters are observed in simulation results. [ABSTRACT FROM AUTHOR]

This work presents the uncertainty analysis of an artificial neural network (ANN)-based method, called multiharmonic ANN fitting method (MANNFM), which is able to obtain, at a metrological level, the spectrum of asynchronously sampled periodical signals. For sinusoidal and harmonic content signals, jitter and quantization noise contributions to uncertainty are considered in order to obtain amplitude and phase uncertainties using Monte Carlo method. The analysis performed identifies also both contributions to uncertainty for different parameters laboratory configurations. The analysis is performed simultaneously with our method and two others: discrete Fourier transform (DFT), for synchronously sampled signals, and multiharmonic sine-fitting method (MSFM), for asynchronously sampled signals, in order to compare them in terms of uncertainty. Regarding asynchronous methods, results show that MANNFM provides the same uncertainties than MSFM, with the advantage of a simpler implementation. Regarding asynchronous and synchronous methods comparison, results for sinusoidal signals show that MANNFM has the same uncertainty as DFT for amplitude and higher uncertainty for phase values; for signals with harmonic content, amplitude conclusions maintain but, regarding phase, both MANNFM and DFT uncertainties become closer as the frequency increases, which implies, in fact, that when synchronous sampling is not possible, spectrum analysis can be performed with asynchronous methods without incurring in uncertainty increases. [ABSTRACT FROM AUTHOR]

The phytoplankton community of tuna farms in Bahía de La Paz, southern Baja California, Mexico was studied. Samples were taken from tuna farms near San Juan de la Costa, Rancheros del Mar and from a station in El Mogote, away from the influence of these farms. Water samples were collected monthly (June 2006-May 2007) with a van Dorn bottle at different depths in San Juan de la Costa (0, 25 and 50 m), Rancheros del Mar (0, 15 and 30 m) and El Mogote (0 m) to measure temperature, dissolved oxygen, inorganic nutrients, and chlorophyll-a and to determine phytoplankton composition and abundance. The index of simple dominance, Shannon-Weaver diversity, and Pielou evenness were estimated. The water column was stratified from June to September (~27.5°C) and mixed from October to May (~18.5°C). Nutrient concentrations at the three sampling sites did not increase significantly. Nanophytoplankton dominated, followed by microplanktonic diatoms, and the highest diatom abundance occurred during the warm period. The phytoplankton community was more diverse in San Juan de la Costa than in Rancheros del Mar. In the latter, a superficial bloom of the cyanobacterium Trichodesmium erythraeum (1630×10³ cel L-1) occurred in September, and in San Juan de la Costa the diatom Pseudo-nitzschia fraudulenta reached the highest abundance (183.8×10³ cel L-1) in July. [ABSTRACT FROM AUTHOR]

Autonomous mobile nodes in mobile wireless sensor networks (MWSN) allow self-deployment and self-healing. In both cases, the goals are: (i) to achieve adequate coverage; and (ii) to extend network life. In dynamic environments, nodes may use reactive algorithms so that each node locally decides when and where to move. This paper presents a behavior-based deployment and self-healing algorithm based on the social potential fields algorithm. In the proposed algorithm, nodes are attached to low cost robots to autonomously navigate in the coverage area. The proposed algorithm has been tested in environments with and without obstacles. Our study also analyzes the differences between non-hierarchical and hierarchical routing configurations in terms of network life and coverage. [ABSTRACT FROM AUTHOR]

Sulphur (S) is an essential element for all living organisms. The uptake, assimilation and metabolism of S in plants are well studied. However, the regulation of S homeostasis remains largely unknown. Here, we report on the identification and characterisation of the more sulphur accumulation1 (msa1-1) mutant. The MSA1 protein is localized to the nucleus and is required for both S-adenosylmethionine (SAM) production and DNA methylation. Loss of function of the nuclear localised MSA1 leads to a reduction in SAM in roots and a strong S-deficiency response even at ample S supply, causing an over-accumulation of sulphate, sulphite, cysteine and glutathione. Supplementation with SAM suppresses this high S phenotype. Furthermore, mutation of MSA1 affects genome-wide DNA methylation, including the methylation of S-deficiency responsive genes. Elevated S accumulation in msa1-1 requires the increased expression of the sulphate transporter genes SULTR1;1 and SULTR1;2 which are also differentially methylated in msa1-1. Our results suggest a novel function for MSA1 in the nucleus in regulating SAM biosynthesis and maintaining S homeostasis epigenetically via DNA methylation. [ABSTRACT FROM AUTHOR]

In mobile wireless sensor networks (MWSN), nodes are allowed to move autonomously for deployment. This process is meant: (i) to achieve good coverage; and (ii) to distribute the communication load as homogeneously as possible. Rather than optimizing deployment, reactive algorithms are based on a set of rules or behaviors, so nodes can determine when to move. This paper presents an experimental evaluation of both reactive deployment approaches: rule-based and behavior-based ones. Specifically, we compare a backbone dispersion algorithm with a social potential fields algorithm. Most tests are done under simulation for a large number of nodes in environments with and without obstacles. Results are validated using a small robot network in the real world. Our results show that behavior-based deployment tends to provide better coverage and communication balance, especially for a large number of nodes in areas with obstacles. [ABSTRACT FROM AUTHOR]

This paper presents the construction of a numerical method for implementing algorithms that are based on a gradient flow. In particular, continuous Hopfield networks for solving optimization problems are considered as a case in point. The focus is the preservation of the favourable properties of the continuous system under discretization. Firstly, the conventional discretization is formulated as a non-standard numerical method that solves the continuous equation, depending on the step size. A rigourous theoretical analysis shows that it is a consistent method, but it fails to preserve the gradient nature, since periodic solutions occur, so no Lyapunov function can exist. Next we present the construction of a method that preserves the Lyapunov function of the original differential equation regardless of the step size. This procedure, based upon discrete gradients, yields an algorithm that preserves the Lyapunov function of the continuous system, thus reproducing the same qualitative behaviour, namely stability of equilibria and convergence to solutions. A remarkable property of the proposed technique is that it can be computed explicitly as long as the Lyapunov function is multi-linear, which is the case of Hopfield neural networks. This results in enhanced performance, compared to the conventional discretization, as shown in a comprehensive set of numerical experiments. [ABSTRACT FROM AUTHOR]

The paralytic shellfish toxin (PST) profiles ofGymnodinium catenatumGraham have been reported for several strains from the Pacific coast of Mexico cultured under different laboratory conditions, as well as from natural populations. Up to 15 saxitoxin analogues occurred and the quantity of each toxin depended on the growth phase and culture conditions. Previous analysis of toxin profiles ofG. catenatumisolated from Mexico have been based on post-column oxidation liquid chromatography with fluorescence detection (LC-FLD), a method prone to artefacts and non-specificity, leading to misinterpretation of toxin composition. We describe, for the first time, the complete toxin profile for severalG. catenatumstrains from diverse locations of the Pacific coast of Mexico. The new results confirmed previous reports on the dominance of the less potent sulfocarbamoyl toxins (C1/2); significant differences, however, in the composition (e.g., absence of saxitoxin, gonyautoxin 2/3 and neosaxitoxin) were revealed in our confirmatory analysis. The LC-MS/MS analyses also indicated at least seven putative benzoyl toxin analogues and provided support for their existence. This new toxin profile shows a high similarity (> 80%) to the profiles reported from several regions around the world, suggesting low genetic variability among global populations. [ABSTRACT FROM AUTHOR]

Temperature and nutrient concentrations were measured during a mixed bloom of Noctiluca scintillans and Gymnodinium catenatum in La Paz Bay, Gulf of California. Under laboratory conditions, we offered three concentrations of G. catenatum (312, 625, or 1015 cells mL-1) to 0.53 N. scintillans cells mL-1 to study predation rates. Experiments were carried out with 750 mL of culture during a fiveday period. Sea surface temperature clearly showed a transitional period from colder to warmer water during the bloom. Field and laboratory data showed that N. scintillans fed on G. catenatum. During the trial, more than 70% of N. scintillans cells contained G. catenatum cells in their vacuoles. Ingestion rates varied; the highest ranged from 30 to 40 G. catenatum cells h-1 in each N. scintillans cell. A clear relation to the concentration of the diet was not evident. Low values of 1 to 3 G. catenatum cells h-1 in each N. scintillans cell were typical at the end of the trial. Noctiluca scintillans doubled in concentration about every 48 h; however, numerous trophonts were observed leaving the cytoplasmic membrane, suggesting cell damage. These data indicate that N. scintillans ingests G. catenatum cells but the prey appears to damage predator cells in a relatively short time. [ABSTRACT FROM AUTHOR]

Vehicular emissions are a predominant source of pollution in urban environments. However, inherent complexities of vehicular behavior are sources of uncertainties in emission inventories (EIs). We compare bottom-up and top-down approaches for estimating road transport EIs in Manizales, Colombia. The EIs were estimated using a COPERT model, and results from both approaches were also compared with the official top-down EI (estimated from IVE methodology). The transportation model PTV-VISUM was used for obtaining specific activity information (traffic volumes, vehicular speed) in bottom-up estimation. Results from COPERT showed lower emissions from the top-down approach than from the bottom-up approach, mainly for NMVOC (−28%), PM10 (−26%), and CO (−23%). Comparisons showed that COPERT estimated lower emissions than IVE, with higher differences than 40% for species such as PM10, NOX, and CH4. Furthermore, the WRF–Chem model was used to test the sensitivity of CO, O3, PM10, and PM2.5 predictions to the different EIs evaluated. All studied pollutants exhibited a strong sensitivity to the emission factors implemented in EIs. The COPERT/top-down was the EI that produced more significant errors. This work shows the importance of performing bottom-up EI to reduce the uncertainty regarding top-down activity data. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Testing is a key stage in system development, particularly in systems such as a wheelchair, in which the final user is typically a disabled person. These systems have stringent safety requirements, requiring major testing with many different individuals. The best would be to have the wheelchair tested by many different end users, as each disability affects driving skills in a different way. Unfortunately, from a practical point of view it is difficult to engage end users as beta testers. Hence, testing often relies on simulations. Naturally, these simulations need to be as realistic as possible to make the system robust and safe before real tests can be accomplished. This work presents a tool to automatically test wheelchairs through realistic emulation of different wheelchair users. Methods and materials: Our approach is based on extracting meaningful data from real users driving a power wheelchair autonomously. This data is then used to train a case-based reasoning (CBR) system that captures the specifics of the driver via learning. The resulting case-base is then used to emulate the driving behavior of that specific person in more complex situations or when a new assistive algorithm needs to be tested. CBR returns user''s motion commands appropriate for each specific situation to add the human component to shared control systems. Results: The proposed system has been used to emulate several power wheelchair users presenting different disabilities. Data to create this emulation was obtained from previous wheelchair navigation experiments with 35 volunteer in-patients presenting different degrees of disability. CBR was trained with a limited number of scenarios for each volunteer. Results proved that: (i) emulated and real users returned similar paths in the same scenario (maximum and mean path deviations are equal to 23 and 10cm, respectively) and similar efficiency; (ii) we established the generality of our approach taking a new path not present in the training traces; (iii) the emulated user is more realistic – path and efficiency are less homogeneous and smooth – than potential field approaches; and (iv) the system adequately emulates in-patients – maximum and mean path deviations are equal to 19 and 8.3cm approximately and efficiencies are similar – with specific disabilities (apraxia and dementia) obtaining different behaviors during emulation for each of the in-patients, as expected. Conclusions: The proposed system adequately emulates the driving behavior of people with different disabilities in indoor scenarios. This approach is suitable to emulate real users’ driving behaviors for early testing stages of assistive navigation systems. [Copyright &y& Elsevier]

Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88 µM DIN, 0.78 µM PO4 and 24.34µM SiO2) were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x 107cells/L). Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC) in local oysters (1525.8μg STXeq/100g), and in phytoplankton (10.9pg STXeq/cells) samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells), most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas of Mexico. [ABSTRACT FROM AUTHOR]

Abstract: This work is aimed at proposing an algorithm, based upon Hopfield networks, for estimating the parameters of delay differential equations. This neural estimator has been successfully applied to models described by Ordinary Differential Equations, whereas its application to systems with delays is a novel contribution. As a case in point, we present a model of dengue fever for the Cuban case, which is defined by a delay differential system. This epidemiological model is built upon the scheme of an SIR (susceptible, infected, recovered) population system, where both delays and time-varying parameters have been included. The latter are thus estimated by the proposed neural algorithm. Additionally, we obtain an expression of the Basic Reproduction Number for our model. Experimental results show the ability of the estimator to deal with systems with delays, providing plausible parameter estimations, which lead to predictions that are coherent with actual epidemiological data. Besides, when the Basic Reproduction Number is computed from the estimated parameter values, results suggest an evolution of the epidemic that is consistent with the observed infection. Hence the estimation could help health authorities to both predict the future trend of the epidemic and assess the efficiency of control measures. [Copyright &y& Elsevier]