Contrasting Geographical Distributions as a Result of Thermal Tolerance and Long-Distance Dispersal in Two Allegedly Widespread Tropical Brown Algae

BackgroundMany tropical marine macroalgae are reported from all three ocean basins, though these very wide distributions may simply be an artifact resulting from inadequate taxonomy that fails to take into account cryptic diversity. Alternatively, pantropical distributions challenge the belief of limited intrinsic dispersal capacity of marine seaweeds and the effectiveness of the north-south oriented continents as dispersal barriers. We aimed to re-assess the distribution of two allegedly circumtropical brown algae, Dictyota ciliolata and D. crenulata, and interpret the realized geographical range of the respective species in relation to their thermal tolerance and major tectonic and climatic events during the Cenozoic.Methodology/Principal FindingsSpecies delimitation was based on 184 chloroplast encoded psbA sequences, using a Generalized Mixed Yule Coalescent method. Phylogenetic relationships were inferred by analyzing a six-gene dataset. Divergence times were estimated using relaxed molecular clock methods and published calibration data. Distribution ranges of the species were inferred from DNA-confirmed records, complemented with credible literature data and herbarium vouchers. Temperature tolerances of the species were determined by correlating distribution records with local SST values. We found considerable conflict between traditional and DNA-based species definitions. Dictyota crenulata consists of several pseudocryptic species, which have restricted distributions in the Atlantic Ocean and Pacific Central America. In contrast, the pantropical distribution of D. ciliolata is confirmed and linked to its significantly wider temperature tolerance.Conclusions/SignificanceTectonically driven rearrangements of physical barriers left an unequivocal imprint on the current diversity patterns of marine macroalgae, as witnessed by the D. crenulata–complex. The nearly circumglobal tropical distribution of D. ciliolata, however, demonstrates that the north-south oriented continents do not present absolute dispersal barriers for species characterized by wide temperature tolerances

Rate and duration of hospitalisation for acute pulmonary embolism in the real-world clinical practice of different countries : Analysis from the RIETE registry

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Evolution of the use of corticosteroids for the treatment of hospitalised COVID-19 patients in Spain between March and November 2020: SEMI-COVID national registry

Objectives: Since the results of the RECOVERY trial, WHO recommendations about the use of corticosteroids (CTs) in COVID-19 have changed. The aim of the study is to analyse the evolutive use of CTs in Spain during the pandemic to assess the potential influence of new recommendations. Material and methods: A retrospective, descriptive, and observational study was conducted on adults hospitalised due to COVID-19 in Spain who were included in the SEMI-COVID- 19 Registry from March to November 2020. Results: CTs were used in 6053 (36.21%) of the included patients. The patients were older (mean (SD)) (69.6 (14.6) vs. 66.0 (16.8) years; p < 0.001), with hypertension (57.0% vs. 47.7%; p < 0.001), obesity (26.4% vs. 19.3%; p < 0.0001), and multimorbidity prevalence (20.6% vs. 16.1%; p < 0.001). These patients had higher values (mean (95% CI)) of C-reactive protein (CRP) (86 (32.7-160) vs. 49.3 (16-109) mg/dL; p < 0.001), ferritin (791 (393-1534) vs. 470 (236- 996) µg/dL; p < 0.001), D dimer (750 (430-1400) vs. 617 (345-1180) µg/dL; p < 0.001), and lower Sp02/Fi02 (266 (91.1) vs. 301 (101); p < 0.001). Since June 2020, there was an increment in the use of CTs (March vs. September; p < 0.001). Overall, 20% did not receive steroids, and 40% received less than 200 mg accumulated prednisone equivalent dose (APED). Severe patients are treated with higher doses. The mortality benefit was observed in patients with oxygen saturation </=90%. Conclusions: Patients with greater comorbidity, severity, and inflammatory markers were those treated with CTs. In severe patients, there is a trend towards the use of higher doses. The mortality benefit was observed in patients with oxygen saturation </=90%

On some properties of the Laplacian matrix revealed by the RCM algorithm

In this paper we present some theoretical results about the irreducibility of the Laplacian matrix ordered by the Reverse Cuthill-McKee (RCM) algorithm. We consider undirected graphs with no loops consisting of some connected components. RCM is a well-known scheme for numbering the nodes of a network in such a way that the corresponding adjacency matrix has a narrow bandwidth. Inspired by some properties of the eigenvectors of a Laplacian matrix, we derive some properties based on row sums of a Laplacian matrix that was reordered by the RCM algorithm. One of the theoretical results serves as a basis for writing an easy MATLAB code to detect connected components, by using the function “symrcm” of MATLAB. Some examples illustrate the theoretical results.The research has been supported by Spanish DGI grant MTM2010-18674, Consolider Ingenio CSD2007-00022, PROMETEO 2008/051, OVAMAH TIN2009-13839-C03-01, and PAID-06-11-2084.Pedroche Sánchez, F.; Rebollo Pedruelo, M.; Carrascosa Casamayor, C.; Palomares Chust, A. (2016). On some properties of the Laplacian matrix revealed by the RCM algorithm. Czechoslovak Mathematical Journal. 66(3):603-620. doi:10.1007/s10587-016-0281-yS60362066

SUBDIRECT SUMS OF S-STRICTLY DIAGONALLY DOMINANT MATRICES

Conditions are given which guarantee that the k-subdirect sum of S-strictly diagonally dominant matrices (S-SDD) is also S-SDD. The same situation is analyzed for SDD matrices. The converse is also studied: given an SDD matrix C with the structure of a k-subdirect sum and positive diagonal entries, it is shown that there are two SDD matrices whose subdirect sum is C

Overlapping Additive and Multiplicative Schwarz Iterations for H-matrices

AbstractIn recent years, an algebraic framework was introduced for the analysis of convergence of Schwarz methods for the solution of linear systems of the form Ax=b. Within this framework, additive and multiplicative Schwarz were shown to converge when the coefficient matrix A is a nonsingular M-matrix, or a symmetric positive definite matrix. In this paper, many of these results are extended to the case of A being an H-matrix. The case of inexact local solves is also considered. In addition, the two-level scheme is studied, i.e., when a coarse grid correction is used in conjunction with the additive or the multiplicative Schwarz iterations

Bovine trypsin immobilization on agarose activated with divinylsulfone: Improved activity and stability via multipoint covalent attachment

© 2015 Elsevier B.V. All rights reserved. Trypsin has been immobilized on divinyl sulfone (DVS) activated agarose at pH 5, 7 and 10. While at pH 5 and 7 immobilization was slow and presented a negative effect on enzyme activity, the immobilization at pH 10 produced a significant increment of activity (by a 24 fold factor). Using this preparation, the effect on enzyme activity/stability of different blocking reagents (used as an enzyme-support reaction end point) were evaluated, selecting ethylenediamine (EDA) because it produced an increase in enzyme activity (a 4 fold factor) and the best results in terms of stability. Next, the effect of alkaline incubation on enzyme activity/stability before the blocking step was analyzed. Activity decreased by 40% after 72 h (but it should be considered that previously it had increased by a 24 fold factor), but the stability significantly improved after this incubation. Thus, after immobilization at different pH values, the immobilized trypsin was submitted to 72 h of alkaline incubation and blocked with EDA. The most active and stable preparation was that immobilized at pH 10. This preparation was less stable than the glyoxyl preparation in thermal inactivations (by less than a twofold factor), but was more stable in organic solvent inactivation (also by less than a twofold factor). The number of groups involved in the enzyme support attachment was 6 Lys using glyoxyl and became a minimum of 13 (including Lys, Tyr and His) using the DVS-activated support (the precision of the method did not permit to analyze the implication of some of the 3 terminal amino groups). Thus, this DVS-agarose support seems to be a very promising support to permit a very intense enzyme-support multipoint covalent attachment.We gratefully recognize the support from the Spanish Government (MINECO; grant CTQ2013-41507-R). The predoctoral fellowships for Mr dos Santos (CNPq, Brazil) and Ms Rueda (Colciencias, Colombia) are also recognized. The help and comments from Dr. Ángel Berenguer (Instituto de Materiales, Universidad de Alicante) are kindly acknowledgedPeer Reviewe