Quantum transport in quantum networks and photosynthetic complexes at the steady state

Recently, several works have analysed the efficiency of photosynthetic complexes in a transient scenario and how that efficiency is affected by environmental noise. Here, following a quantum master equation approach, we study the energy and excitation transport in fully connected networks both in general and in the particular case of the Fenna-Matthew-Olson complex. The analysis is carried out for the steady state of the system where the excitation energy is constantly "flowing" through the system. Steady state transport scenarios are particularly relevant if the evolution of the quantum system is not conditioned on the arrival of individual excitations. By adding dephasing to the system, we analyse the possibility of noise-enhancement of the quantum transport.Comment: 10 pages, single column, 6 figures. Accepted for publication in Plos On

Disintegrins extracted from totonacan rattlesnake (Crotalus totonacus) venom and their anti-adhesive and anti-migration effects on MDA-MB-231 and HMEC-1 cells

Disintegrins are low molecular weight cysteine-rich proteins (4–14 kDa) that are isolated mainly from viperid snake venom. Due to their potential as lead compounds for binding and blocking integrin receptors, snake venom disintegrins have become one of the most studied venom protein families. The aim of this study was to obtain disintegrins from C. totonacus venom and evaluate their capability to bind and block integrin receptors. The C. totonacus disintegrin fraction (totonacin) represents two disintegrin isoforms obtained from C. totonacus venom. These disintegrins showed extracellular-matrix (ECM) protein adhesion and migration inhibitory effects on MDA-MB-231 and HMEC-1 cells. Totonacin (3 μM) inhibited MDA-MB-231 cell adhesion to the ECM proteins, fibronectin, vitronectin, and laminin by 31.2, 44.0, and 32.1, respectively. Adhesion inhibition to fibronectin, vitronectin, and laminin observed on HMEC-1 cells was 42.8, 60.8, and 51%, respectively. In addition, totonacin (3 μM) significantly inhibited MDA-MB-231 and HMEC-1 cell migration (41.4 and 48.3%, respectively). Totonacin showed more potent cell adhesion inhibitory activity toward vitronectin in both cell lines. These results suggest a major affinity of totonacin toward αVβ3, α8β1, αVβ5, αVβ1, and αIIbβ3 integrins. In addition, the inhibitory effect observed on MDA-MB-231 and HMEC-1 cell migration reinforces the evidence of an interaction between these disintegrins and αVβ3 integrin, which plays a key role in migration and angiogenesis

Optimising models for prediction of tropospheric scintillation on satellite links

A phenomenon that also causes impairment in the received signal strength of the RF signal in satellite links operating at frequencies above 10 GHz, especially in those systems that operate at higher frequencies with small fade margins, is the tropospheric scintillation that occurs in the lower layer of the troposphere. In order to estimate the intensity, i.e. the variance between the scintillation amplitude fluctuations, there are several models in the literature, whose accuracy depends on the locality in which the models are implemented. In this Letter, new models are developed for the prediction of tropospheric scintillation that adjusts to localities in Spain, specifically Madrid city, based on measurements of the aforementioned phenomenon reported from Spain and the bios-inspired technique Cuckoo Search (CS). The results obtained, evaluated in terms of the root mean square error, were totally satisfactory, being the most outstanding cases the improved versions of the Ortgies-T, Statistical Temperature and Humidity 2 and Statistical Temperature and Refractivity 2 models

Bacteriocinogenic Lactic Acid Bacteria of Caprine Products from Chaco – Argentina

The microbiota of artisanal caprine products is essential for the manufacture of fermented products, such as cheeses and dry sausages, conferring them particular and distinctive flavors and generating high value-added products. Many of the bacteria comprising this microbiota are able to produce bacteriocins and antimicrobial substances. The finding of bacteriocinogenic strains within this microbiota could be the first step to introduce biopreservation into these products. Hence, ten lactic acid bacteria (LAB) (6 Lactobacillus paracasei, 2 Lactococcus lactis, 1 Leuconostoc mesenteroides and 1 Lactobacillus rhamnosus) isolated from artisanal caprine products from Chaco (Argentina) were screened for antagonistic activity against other LAB and some spoilage and pathogenic microorganisms, such as Listeria innocua (in lieu of Listeria monocytogenes), Staphylococcus aureus and Escherichia coli. The final goal was to investigate LAB antibacterial activity within this unexplored ecological niche and to select interesting strains for the role of bio-preservatives. Bacteriocin-like substances (BLIS) produced by the isolated strains inhibited three species of S. aureus, L. innocua and Brochothrix thermosphacta. Titles of these antibacterial substances were within the range 100-200 AU.mL-1. BLIS produced by the isolated strains were heat stable and effective after refrigerated storage and freeze/thaw cycles. Moreover, BLIS activity was higher at acidic pH values, showing a decrease when these values were closer to neutrality or they become alkaline. BLIS did not adsorb to the producer cells which is expected for future production and application on food systems. The results presented in this study could contribute to characterize the antimicrobial activity of the indigenous flora of artisanal caprine products manufactured in the province of Chaco, Argentina. The isolated bacteriocinogenic strains showed a regular production of BLIS in culture broth, which offers promising applications for the biopreservation of these products

Trophic models and short-term dynamic simulations for benthic-pelagic communities at Banco Chinchorro Biosphere Reserve (Mexican Caribbean): a conservation case

Banco Chinchorro is the largest reef in the Mexican Caribbean. Historically, spiny lobster, queen conch and over 20 other reef species have been exploited here. Multispecies intervention management from an ecosystem perspective has been developed in this area; however, an assessment of the effects of such practices on ecosystem health is required. Five quantitative trophic models were constructed using Ecopath with Ecosim. The results show that, in terms of biomass, benthic autotrophs are the dominant group in all communities. Ecosystem Network Analysis indices showed that Cueva de Tiburones was the most mature, developed, complex and healthy subsystem, but, El Colorado and La Baliza were the subsystems most resistant to disturbances. The fisheries mainly concentrate on primary (La Baliza and Cueva de Tiburones sites) and secondary consumers (La Caldera, Chancay, and El Colorado). The greatest propagation of direct and indirect effects, estimated by Mixed Trophic Impacts and Ecosim simulations, were generated by the benthic autotrophs, small benthic epifauna, benthic-pelagic carnivorous fish and benthic carnivorous fish, among others. In contrast, the System Recovery Time showed different patterns among subsystems, indicating several compartments that reduce resilience. Considering the structure, dynamics, trophic functioning and ecosystem health of Banco Chinchorro, its ecological heterogeneity highlights the need for the design of a specific (by subsystem) management strategy, particularly because different species or functional groups present greater sensitivity to human interventions in each community

Linear Momentum Density in Quasistatic Electromagnetic Systems

We discuss a couple of simple quasistatic electromagnetic systems in which the density of electromagnetic linear momentum can be easily computed. The examples are also used to illustrate how the total electromagnetic linear momentum, which may also be calculated by using the vector potential, can be understood as a consequence of the violation of the action-reaction principle, because a non-null external force is required to maintain constant the mechanical linear momentum. We show how one can avoid the divergence in the interaction linear electromagnetic momentum of a system composed by an idealization often used in textbooks (an infinite straight current) and a point charge.Comment: 22 pages, 5 figures, to appear in Eur. J. Phy

Estatinas y factor de necrosis tumoral alfa

Las Estatinas son elaboradas para eliminar el riesgo cardiovascular al reducir LDL (colesterol de baja densidad), pero el evento coronario agudo sigue ocurriendo en 40% de las personas que presentaban colesterol total por debajo de lo normal. El objetivo de este estudio fue evaluar si dentro de los efectos pleiotropicos de las estatinas se podía reducir el FNTα y con ello probar sus efectos antioxidantes e inflamatorios. Se evaluaron 21 pacientes, con hipercolesterolemia al ingreso y después de 8 semanas de recibir 40 mg de Simvastatina, se le realizó: Colesterol, Triglicéridos, HDL, LDL, Glicemia, Creatinina, Acido Úrico, PCR, IL-1, IL-6, IL-10, TNFα, SOD y 8-Isoprostanos F2. Se utilizo la prueba t de student. La estatina, mas allá de disminuir LDL es eficaz en disminuir variables que participan en la respuesta oxidativa e inflamatoria, mecanismo fisiopatologico constantes en las enfermedades cardiovasculares y metabólicas.Statins are developed to eliminate the risk of heart disease by reducing LDL (low density), but the acute coronary event still happened in 40% of those who had total cholesterol below normal. The aim of this study was to assess whether in the pleiotropic effects of statins could reduce TNF α and thus prove its antioxidant and inflammatory effects. We evaluated 21 patients with hypercholesterolemia on admission and after 8 weeks of receiving 40 mg simvastatin, we evaluated: Cholesterol, Triglycerides, HDL, LDL, Glucose, Creatinine, uric acid, CRP, IL-1, IL-6, IL-10, TNF, SOD and 8-isoprostane F2α. T test was used to student. The statin beyond to reduced LDL is effective in decreasing variables involved in the inflammatory response, consistent pathophysiological mechanism in cardiovascular and metabolic diseases

Computational Methodologies and Physical Insights into Electronic Energy Transfer in Photosynthetic Light-Harvesting Complexes

We examine computational techniques and methodologies currently in use to explore electronic excitation energy transfer in the context of light-harvesting complexes in photosynthetic antenna systems, and comment on some new insights into the underlying physics. Advantages and pitfalls of these methodologies are discussed, as are some physical insights into the photosynthetic dynamics. By combining results from molecular modelling of the complexes (structural description) with an effective non-equilibrium statistical description (time evolution), we identify some general features, regardless of the particular distribution in the protein scaffold, that are central to light-harvesting dynamics and, that could ultimately be related to the high efficiency of the overall process. Based on these general common features, some possible new directions in the field are discussed.Comment: Invited Perspective Article for Phys. Chem. Chem. Phy

Integrated Genomic Analysis of Chromosomal Alterations and Mutations in B-Cell Acute Lymphoblastic Leukemia Reveals Distinct Genetic Profiles at Relapse

The clonal basis of relapse in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is complex and not fully understood. Next-generation sequencing (NGS), array comparative genomic hybridization (aCGH), and multiplex ligation-dependent probe amplification (MLPA) were carried out in matched diagnosis-relapse samples from 13 BCP-ALL patients to identify patterns of genetic evolution that could account for the phenotypic changes associated with disease relapse. The integrative genomic analysis of aCGH, MLPA and NGS revealed that 100% of the BCP-ALL patients showed at least one genetic alteration at diagnosis and relapse. In addition, there was a significant increase in the frequency of chromosomal lesions at the time of relapse (p = 0.019). MLPA and aCGH techniques showed that IKZF1 was the most frequently deleted gene. TP53 was the most frequently mutated gene at relapse. Two TP53 mutations were detected only at relapse, whereas the three others showed an increase in their mutational burden at relapse. Clonal evolution patterns were heterogeneous, involving the acquisition, loss and maintenance of lesions at relapse. Therefore, this study provides additional evidence that BCP-ALL is a genetically dynamic disease with distinct genetic profiles at diagnosis and relapse. Integrative NGS, aCGH and MLPA analysis enables better molecular characterization of the genetic profile in BCP-ALL patients during the evolution from diagnosis to relapse