Conectividad tridimensional durante el verano en el norte del Golfo de California

Connectivity studies in the Gulf of California are an important tool for improving the use and management of the gulf’s natural resources. The goal of this work was to study the three-dimensional connectivity in the northern Gulf of California during two representative months of summer when most local marine species spawn. Passive particles were advected for eight weeks in a three-dimensional current field generated by a three-dimensional baroclinic numerical model. The results indicate that the locations of greatest particle retention were the Upper Gulf and the Seasonal Eddy. The Seasonal Eddy corresponded to the area of largest particle catchment because the continental coastal current carries most particles released in the Midriff Archipelago region; subsequently these particles were entrained in the seasonal cyclonic eddy, causing most of them to remain within it. We conclude that the continental coastal current and the Seasonal Eddy control the connectivity patterns in the northern Gulf of California.Los estudios de conectividad en el Golfo de California (GC) son una herramienta importante para mejorar el uso y la gestión de los recursos naturales del golfo. El objetivo de este trabajo fue estudiar la conectividad tridimensional en el norte del Golfo de California (NGC) durante dos meses representativos de verano, ya que es la temporada con mayor desove de especies marinas. Se advectaron partículas pasivas durante ocho semanas en un campo de corrientes tridimensional generado por un modelo numérico baroclínico tridimensional. Los resultados indicaron que los lugares con mayor retención de las partículas fueron el Alto Golfo (UG) y el Remolino Estacional (SE). A su vez, SE fue el área de máxima captación de partículas debido a que la corriente costera continental transporta la mayoría de las partículas liberadas en las localidades ubicadas en la zona de las Grandes Islas, posteriormente estas partículas son atrapadas por el remolino ciclónico estacional lo que provocó que la mayoría de las partículas liberadas se queden dentro de éste. Por último, concluimos que la corriente costera continental y el remolino estacional controlan los patrones de conectividad en el NGC

Body water distribution in severe obesity and its assessment from eight-polar bioelectrical impedance analysis

Objective: To measure body water distribution and to evaluate the accuracy of eight-polar bioelectrical impedance analysis (BIA) for the assessment of total body water (TBW) and extracellular water (ECW) in severe obesity. Design: Cross-sectional study. Setting: Obesity clinic. Subjects: In all, 75 women aged 18-66 y, 25 with body mass index (BMI) between 19.1 and 29.9 kg/m(2) (ie not obese), 25 with BMI between 30.0 and 39.9 kg/m(2) (ie class I and II obese), and 25 with BMI between 40.0 and 48.2 kg/m(2) (ie class III obese). Methods: TBW and ECW were measured by (H2O)-H-2 and Br dilution. Body resistance (R) was obtained by summing the resistances of arms, trunk and legs as measured by eight-polar BIA (InBody 3.0, Biospace, Seoul, Korea). The resistance index at a frequency of x kHz (RIx) was calculated as height 2/R-x. Results: ECW: TBW was similar in women with class III (46 +/- 3%, mean +/- s.d.) and class I-II obesity (45 +/- 3%) but higher than in nonobese women (39 +/- 3%, P < 0.05). In a random subsample of 37 subjects, RI500 explained 82% of TBW variance (P < 0.0001) and cross-validation of the obtained algorithm in the remaining 38 subjects gave a percent root mean square error (RMSE%) of 5% and a pure error (PE) of 2.1 l. In the same subjects, RI5 explained 87% of ECW variance (P < 0.0001) and cross-validation of the obtained algorithm gave a RMSE% of 8% and a PE of 1.4 l. The contribution of weight and BMI to the prediction of TBW and ECW was nil or negligible on practical grounds. Conclusions: ECW: TBW is similar in women with class I-II and class III obesity up to BMI values of 48.2 kg/m(2). Eight-polar BIA offers accurate estimates of TBW and ECW in women with a wide range of BMI (19.1-48.2 kg/m(2)) without the need of population-specific formulae

Results of a New Passive RF Stabilizing System

The method developed at the Milan AVF Cyclotron for stabilizing the RF accelerating voltage is a passive network where the desired stabilization is achieved by a dummy resistive load connected to the Dee and driven by the RF voltage amplitude. A small amount of the power is extracted from the Dee through a capacitive coupling and feeds the plates of two tubes operating in push-pull mode

Influence of topography on tide propagation and amplification in semi-enclosed basins

An idealized model for tide propagation and amplification in semi-enclosed rectangular basins is presented, accounting for depth differences by a combination of longitudinal and lateral topographic steps. The basin geometry is formed by several adjacent compartments of identical width, each having either a uniform depth or two depths separated by a transverse topographic step. The problem is forced by an incoming Kelvin wave at the open end, while allowing waves to radiate outward. The solution in each compartment is written as the superposition of (semi)-analytical wave solutions in an infinite channel, individually satisfying the depth-averaged linear shallow water equations on the f plane, including bottom friction. A collocation technique is employed to satisfy continuity of elevation and flux across the longitudinal topographic steps between the compartments. The model results show that the tidal wave in shallow parts displays slower propagation, enhanced dissipation and amplified amplitudes. This reveals a resonance mechanism, occurring when\ud the length of the shallow end is roughly an odd multiple of the quarter Kelvin wavelength. Alternatively, for sufficiently wide basins, also Poincaré waves may become resonant. A transverse step implies different wavelengths of the incoming and reflected Kelvin wave, leading to increased amplitudes in shallow regions and a shift of amphidromic points in the direction of the deeper part. Including the shallow parts near the basin’s closed end (thus capturing the Kelvin resonance mechanism) is essential to reproduce semi-diurnal and diurnal\ud tide observations in the Gulf of California, the Adriatic Sea and the Persian Gulf

Molecular dynamics simulations of the Salmonella typhi Vi antigenic polysaccharide and effects of the introduction of a zwitterionic motif

A series of hexasaccharides corresponding to the Vi capsular polysaccharide, a polymer of \u3b1-(1\u21924)-galacturonic acid, and analogs containing a zwitterionic motif with various degrees of acetylation at positions 3 have been modeled. When submitted to molecular dynamics simulations in a water box, all the structures visited only two quite restricted regions of the /\u3c8 conformational space both corresponding to extended geometries without any tendency towards supercoiling. The most stable conformation showed a clockwise helix arrangement of substituents on the molecular surface whereas the opposite arrangement was observed for the other conformation. The flexibility of the system and the hydrophobic character of the molecular surface are modulated by the 3-O-acetyl groups that confer rigidity to the system. In the zwitterionic analogs, the introduction of positive charges in the place of the acetamido groups alters the hydrophobicity that can be regained by methylation of the amino groups. The needed molecular flexibility can be obtained by the complete deacetylation at positions 3

Rapid Effects of Marine Reserves via Larval Dispersal

Marine reserves have been advocated worldwide as conservation and fishery management tools. It is argued that they can protect ecosystems and also benefit fisheries via density-dependent spillover of adults and enhanced larval dispersal into fishing areas. However, while evidence has shown that marine reserves can meet conservation targets, their effects on fisheries are less understood. In particular, the basic question of if and over what temporal and spatial scales reserves can benefit fished populations via larval dispersal remains unanswered. We tested predictions of a larval transport model for a marine reserve network in the Gulf of California, Mexico, via field oceanography and repeated density counts of recently settled juvenile commercial mollusks before and after reserve establishment. We show that local retention of larvae within a reserve network can take place with enhanced, but spatially-explicit, recruitment to local fisheries. Enhancement occurred rapidly (2 yrs), with up to a three-fold increase in density of juveniles found in fished areas at the downstream edge of the reserve network, but other fishing areas within the network were unaffected. These findings were consistent with our model predictions. Our findings underscore the potential benefits of protecting larval sources and show that enhancement in recruitment can be manifested rapidly. However, benefits can be markedly variable within a local seascape. Hence, effects of marine reserve networks, positive or negative, may be overlooked when only focusing on overall responses and not considering finer spatially-explicit responses within a reserve network and its adjacent fishing grounds. Our results therefore call for future research on marine reserves that addresses this variability in order to help frame appropriate scenarios for the spatial management scales of interest

Telomere length correlates with histopathogenesis according to the germinal center in mature B-cell lymphoproliferative disorders

In this study we investigated telomere restriction fragment (TRF) length in a panel of mature B-cell lymphoproliferative disorders (MBCLDs) and correlated this parameter with histology and histopathogenesis in relation to the germinal center (GC). We assessed 123 MBCLD samples containing 80% or more tumor cells. TRF length was evaluated by Southern blot analysis using a chemiluminescence-based assay. GC status was assessed through screening for stable and ongoing somatic mutations within the immunoglobulin heavy-chain genes. Median TRF length was 6170 bp (range, 1896-11 200 bp) and did not correlate with patient age or sex. TRF length was greater in diffuse large cell lymphoma, Burkitt lymphoma, and follicular lymphoma (medians: 7789 bp, 9471 bp, and 7383 bp, respectively) than in mantle cell lymphoma and chronic lymphocytic leukemia (medians: 3582 bp and 4346 bp, respectively). GC-derived MBCLDs had the longest telomeres, whereas those arising from GC-inexperienced cells had the shortest (P &lt; 10(-9)). We conclude that (1) TRF length in MBCLD is highly heterogeneous; (2) GC-derived tumors have long telomeres, suggesting that minimal telomere erosion occurs during GC-derived lymphomagenesis; and (3) the short TRF lengths of GC-inexperienced MBCLDs indicates that these neoplasms are good candidates for treatment with telomerase inhibitors, a class of molecules currently the subject of extensive preclinical evaluation

Quantifying the Spatial Ecology of Wide-Ranging Marine Species in the Gulf of California: Implications for Marine Conservation Planning

There is growing interest in systematic establishment of marine protected area (MPA) networks and representative conservation sites. This movement toward networks of no-take zones requires that reserves are deliberately and adequately spaced for connectivity. Here, we test the network functionality of an ecoregional assessment configuration of marine conservation areas by evaluating the habitat protection and connectivity offered to wide-ranging fauna in the Gulf of California (GOC, Mexico). We first use expert opinion to identify representative species of wide-ranging fauna of the GOC. These include leopard grouper, hammerhead sharks, California brown pelicans and green sea turtles. Analyzing habitat models with both structural and functional connectivity indexes, our results indicate that the configuration includes large proportions of biologically important habitat for the four species considered (25–40%), particularly, the best quality habitats (46–57%). Our results also show that connectivity levels offered by the conservation area design for these four species may be similar to connectivity levels offered by the entire Gulf of California, thus indicating that connectivity offered by the areas may resemble natural connectivity. The selected focal species comprise different life histories among marine or marine-related vertebrates and are associated with those habitats holding the most biodiversity values (i.e. coastal habitats); our results thus suggest that the proposed configuration may function as a network for connectivity and may adequately represent the marine megafauna in the GOC, including the potential connectivity among habitat patches. This work highlights the range of approaches that can be used to quantify habitat protection and connectivity for wide-ranging marine species in marine reserve networks