Un primer curso sobre Variable Compleja

Este texto tiene como propósito presentar los aspectos introductorios de las funciones de variable compleja para que sirva como texto orientador de los académicos interesados en este tema y, en particular, de los cursos que sobre esta área se ofrecen en los Programas de: Licenciatura en Matemáticas, Física y, parcialmente, Ingeniería Electrónica de la Universidad de Nariño

Fundamentals and Applications of Surface-Enhanced Raman Spectroscopy (SERS)

When a molecule is adsorbed on some metallic nanostructured surfaces such as silver, copper or gold, it can undergo an enormous enhancement of the Raman signal giving rise to the so called Surface-Enhanced Raman Scattering (SERS). The high sensitivity of this effect allows an accurate structural study of adsorbates at very low concentrations. The SERS effect has historically been associated with the substrate roughness on two characteristic length scales. Surface roughness on the 10 to 100 nm length scale supports localized plasmon resonances which are considered as the dominant enhancement mechanism of SERS (Electromagnetic Enhancement Mechanism: SERS-EM). It is usually accepted that these electromagnetic resonances can increase the scattered intensity by an average factor of ca. 104 to 107. A secondary mechanism often thought to require atomic scale roughness is referred to as Charge Transfer (CT) Enhancement Mechanism (SERS-CT). This mechanism involves the photoinduced transfer of an electron from the metal to the adsorbate or vice versa and involves new electronic excited CT states which result from adsorbate–substrate chemical interactions. It is also estimated that such SERS-CT mechanism can enhance the scattering cross-section by a factor of ca. 10 to 102. These two mechanisms can operate simultaneously, depending on the particular systems and experimental conditions, making difficult to recognize each one and to estimate their relative magnitude in a particular spectrum.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

An MS-CASPT2 Study of the Photodecomposition of 4- Methoxyphenyl Azide. Role of Internal Conversion and Intersystem Crossing

Aryl azides photochemistry is strongly dependent on the substituent relative position, as has been studied by time resolved resonant Raman (TR3) spectroscopy for 4-methoxyphenyl azide and its isomer 3-methoxyphenyl azide. When irradiated at 266 nm, the former results in 4,4’-dimethoxyazobenzene whereas the latter forms 1,2-didehydroazepine. It is proposed that the key step of the reactions is the formation of a nitrene derivative. Recently, it has been proposed by us that nitrenes might have a relevant role in the Surface-Enhanced Raman Scattering (SERS) of p-aminothiophenol, however, the molecular mechanism is not well known in neither of these cases. Therefore, we studied the photodecomposition of 4-methoxyphenyl azide using multiconfigurational self-consistent field methods (MC-SCF) with the CAS-SCF and MS-CASPT2 approximations and calculated the resonant Raman spectra of the relevant species using a multi-state version of Albrecht’s vibronic theory. The results propose that the reaction follows a two steps sequence after irradiation at 266 nm: an intersystem crossing 21A’/23A’’ which decays through a 21A’/21A’’ conical intersection producing molecular nitrogen and triplet 4-methoxyphenyl nitrene in its ground state.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Short range order of CCl4: RMC and MD methods

The main objective of this paper is to present a method to fully determine the six degrees of freedom regarding position and orientation of a neighboring molecule around a central one, i.e. the g(rCM,¿) distribution function. This is accomplished by completely determining the short range structure of liquid carbon tetrachloride, while employing results from two different methods, Molecular Dynamics (MD) [1] and Reverse Monte Carlo (RMC) [2]. Exclusively, the structural ordering of the first four molecules will be detailed.Postprint (published version

Suitability of real-time quantitative PCR to estimate the relative telomere length in European Hake (Merluccius merluccius Linnaeus, 1758)

Telomere length measurement has been proposed as a promising tool to estimate the age of individuals in natural populations. We used real-time quantitative PCR (qPCR) to measure relative telomere length in four tissues (brain, kidney, liver and muscle) of European hake (Merluccius merluccius) in different groups based upon body length an otolith age estimate. We observed a high level of inter-individual differences in the measurements of relative telomere length in hakes of similar age and body length groups. The results of qPCR analysis showed a great variability in all measures and a lack of repeatability and reproducibility with significant statistical differences in the results of the different assays. The paper discusses the technical reasons for the variability in qPCR obtained in this work and by other authors

In Silico Analysis of Putative Paralytic Shellfish Poisoning Toxins Export Proteins in Cyanobacteria

Lopez-Cortes, XA (Lopez-Cortes, Xaviera A.) Univ Talca, Nanobiotechnol Div, Fraunhofer Chile Res Fdn, Ctr Syst Biotechnol, Talca, Chile.Paralytic shellfish poisoning toxins (PSTs) are a family of more than 30 natural alkaloids synthesized by dinoflagellates and cyanobacteria whose toxicity in animals is mediated by voltage-gated Na+ channel blocking. The export of PST analogues may be through SxtF and SxtM, two putative MATE (multidrug and toxic compound extrusion) family transporters encoded in PSTs biosynthetic gene cluster (sxt). sxtM is present in every sxt cluster analyzed; however, sxtF is only present in the Cylindrospermopsis-Raphidiopsis clade. These transporters are energetically coupled with an electrochemical gradient of proton (H+) or sodium (Na+) ions across membranes. Because the functional role of PSTs remains unknown and methods for genetic manipulation in PST-producing organisms have not yet been developed, protein structure analyses will allow us to understand their function. By analyzing the sxt cluster of eight PST-producing cyanobacteria, we found no correlation between the presence of sxtF or sxtM and a specific PSTs profile. Phylogenetic analyses of SxtF/M showed a high conservation of SxtF in the Cylindrospermopsis-Raphidiopsis clade, suggesting conserved substrate affinity. Two domains involved in Na+ and drug recognition from NorM proteins (MATE family) of Vibrio parahaemolyticus and V. cholerae are present in SxtF/M. The Na+ recognition domain was conserved in both SxtF/M, indicating that Na+ can maintain the role as a cation anti-transporter. Consensus motifs for toxin binding differed between SxtF and SxtM implying differential substrate binding. Through protein modeling and docking analysis, we found that there is no marked affinity between the recognition domain and a specific PST analogue. This agrees with our previous results of PST export in R. brookii D9, where we observed that the response to Na+ incubation was similar to different analogues. These results reassert the hypothesis regarding the involvement of Na+ in toxin export, as well as the motifs L(398)XGLQD(403) (SxtM) and L(390)VGLRD(395) (SxtF) in toxin recognition

Twenty-four-hour, weekly and annual patterns in serious falls of non-institutionalized independent Spanish seniors.

OBJECTIVE: The study aimed to explore clock hour, day-of-week, and month-of-year patterns of serious falls experienced by non-institutionalized Spanish seniors (age ≥65 years) in relation to associated conventional intrinsic and extrinsic factors. PATIENTS AND METHODS: Intake emergency department records from January 1 to December 31, 2013 of a tertiary hospital of southern Spain were abstracted for particulars of falls, including the time of occurrence, experienced specifically by non-institutionalized seniors. Chi-squares and Single and Multiple-Component Cosinor (time series) Analyses were applied to determine the statistical significance of observed 24-hour, 7-day, and annual variation. RESULTS: Falls were ~2.5-fold more numerous in older women than older men and ~7-fold more frequent between 12:00 and 14:00 hours than ~02:00 hours, respectively, the time spans corresponding to the absolute peak and trough of the 24-hour pattern in falls. The midday/early afternoon peak primarily represented incidents of women ≥75 years of age that occurred inside the home while walking, standing, or moving on stairs. A late evening less prominent excess of mostly inside-the-home incidents of women ≥75 years of age, largely due to fragility, slipping, stumbling, or tripping, was additionally detected. Cosinor Analysis substantiates statistical significance of the 24-hour patterning of falls of men and women (both p<0.001). Day-of-week differences, with prominent Thursday peak and Sunday minimum, were additionally detected, but only for falls of women occurring outside the home (Cosinor Analysis: p=0.007). Day-of-week discrepancy in female/male sex ratio (SR) of fallers was demonstrated, arising from day-of-week disparity in the SR of inside-the-home incidents, with ~4.5-fold more elderly women than elderly men falling Thursday than any other day of the week (p=0.005). Non-statistically significant month-of-year difference in falls, lowest in autumn and highest (~60% more) in winter, was observed and explained by prominent seasonal difference in incidents by elderly women. CONCLUSIONS: Serious falls of non-institutionalized independent seniors are characterized according to intrinsic and extrinsic factors by prominent 24-hour and 7-day patterning. These findings complement the understanding of the epidemiology of falls of the elderly and further inform fall prevention programs

Seasonal pattern in elderly hospitalized with acute kidney injury: a retrospective nationwide study in Italy

Purpose: Acute kidney injury (AKI) frequently complicates hospitalization and is associated with in-hospital mortality (IHM). It has been reported a seasonal trend in different clinical conditions. The aim of this study was to evaluate the possible relationship between seasons of the year and IHM in elderly hospitalized patients with AKI. Methods: We selected all admissions complicated by AKI between 2000 and 2015 recorded in the Italian National Hospital Database. ICD-9-CM code 584.xx identified subjects with age ≥ 65 years and age, sex, comorbidity burden, need of dialysis treatment and IHM were compared in hospitalizations recorded during the four seasons. Moreover, we plotted the AKI observed/expected ratio and percentage of mortality during the study period. Results: We evaluated 759,720 AKI hospitalizations (mean age 80.5 ± 7.8 years, 52.2% males). Patients hospitalized with AKI during winter months had higher age, prevalence of dialysis-dependent AKI, and number of deceased patients. In whole population IHM was higher in winter and lower in summer, while the AKI observed/expected ratio demonstrated two peaks, one in summer and one in winter. Logistic regression analysis demonstrated that parameters such as age, autumn, winter, comorbidity burden were positively associated with IHM. Conclusion: We conclude that a seasonality exists in AKI, however, relationship between seasons and AKI could vary depending on the aspects considered. Both autumn and winter months are independent risk factors for IHM in patients with AKI regardless of age, sex and comorbidity burden. On the contrary, summer time reduces the risk of death during hospitalizations with AKI