Universitat Rovira i Virgili

A suite of climate change indices derived from daily temperature and precipitation data, with a primary focus on extreme events, were computed and analyzed. By setting an exact formula for each index and using specially designed software, analyses done in different countries have been combined seamlessly. This has enabled the presentation of the most up‐to‐date and comprehensive global picture of trends in extreme temperature and precipitation indices using results from a number of workshops held in data‐sparse regions and high‐quality station data supplied by numerous scientists world wide. Seasonal and annual indices for the period 1951–2003 were gridded. Trends in the gridded fields were computed and tested for statistical significance. Results showed widespread significant changes in temperature extremes associated with warming, especially for those indices derived from daily minimum temperature. Over 70% of the global land area sampled showed a significant decrease in the annual occurrence of cold nights and a significant increase in the annual occurrence of warm nights. Some regions experienced a more than doubling of these indices. This implies a positive shift in the distribution of daily minimum temperature throughout the globe. Daily maximum temperature indices showed similar changes but with smaller magnitudes. Precipitation changes showed a widespread and significant increase, but the changes are much less spatially coherent compared with temperature change. Probability distributions of indices derived from approximately 200 temperature and 600 precipitation stations, with near‐complete data for 1901–2003 and covering a very large region of the Northern Hemisphere midlatitudes (and parts of Australia for precipitation) were analyzed for the periods 1901–1950, 1951–1978 and 1979–2003. Results indicate a significant warming throughout the 20th century. Differences in temperature indices distributions are particularly pronounced between the most recent two periods and for those indices related to minimum temperature. An analysis of those indices for which seasonal time series are available shows that these changes occur for all seasons although they are generally least pronounced for September to November. Precipitation indices show a tendency toward wetter conditions throughout the 20th century.

AIMS: To appraise the clinical and genetic evidence that low-density lipoproteins (LDLs) cause atherosclerotic cardiovascular disease (ASCVD). METHODS AND RESULTS: We assessed whether the association between LDL and ASCVD fulfils the criteria for causality by evaluating the totality of evidence from genetic studies, prospective epidemiologic cohort studies, Mendelian randomization studies, and randomized trials of LDL-lowering therapies. In clinical studies, plasma LDL burden is usually estimated by determination of plasma LDL cholesterol level (LDL-C). Rare genetic mutations that cause reduced LDL receptor function lead to markedly higher LDL-C and a dose-dependent increase in the risk of ASCVD, whereas rare variants leading to lower LDL-C are associated with a correspondingly lower risk of ASCVD. Separate meta-analyses of over 200 prospective cohort studies, Mendelian randomization studies, and randomized trials including more than 2 million participants with over 20 million person-years of follow-up and over 150 000 cardiovascular events demonstrate a remarkably consistent dose-dependent log-linear association between the absolute magnitude of exposure of the vasculature to LDL-C and the risk of ASCVD; and this effect appears to increase with increasing duration of exposure to LDL-C. Both the naturally randomized genetic studies and the randomized intervention trials consistently demonstrate that any mechanism of lowering plasma LDL particle concentration should reduce the risk of ASCVD events proportional to the absolute reduction in LDL-C and the cumulative duration of exposure to lower LDL-C, provided that the achieved reduction in LDL-C is concordant with the reduction in LDL particle number and that there are no competing deleterious off-target effects. CONCLUSION: Consistent evidence from numerous and multiple different types of clinical and genetic studies unequivocally establishes that LDL causes ASCVD.

The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article.

Abstract The Twentieth Century Reanalysis (20CR) project is an international effort to produce a comprehensive global atmospheric circulation dataset spanning the twentieth century, assimilating only surface pressure reports and using observed monthly sea‐surface temperature and sea‐ice distributions as boundary conditions. It is chiefly motivated by a need to provide an observational dataset with quantified uncertainties for validations of climate model simulations of the twentieth century on all time‐scales, with emphasis on the statistics of daily weather. It uses an Ensemble Kalman Filter data assimilation method with background ‘first guess’ fields supplied by an ensemble of forecasts from a global numerical weather prediction model. This directly yields a global analysis every 6 hours as the most likely state of the atmosphere, and also an uncertainty estimate of that analysis. The 20CR dataset provides the first estimates of global tropospheric variability, and of the dataset's time‐varying quality, from 1871 to the present at 6‐hourly temporal and 2° spatial resolutions. Intercomparisons with independent radiosonde data indicate that the reanalyses are generally of high quality. The quality in the extratropical Northern Hemisphere throughout the century is similar to that of current three‐day operational NWP forecasts. Intercomparisons over the second half‐century of these surface‐based reanalyses with other reanalyses that also make use of upper‐air and satellite data are equally encouraging. It is anticipated that the 20CR dataset will be a valuable resource to the climate research community for both model validations and diagnostic studies. Some surprising results are already evident. For instance, the long‐term trends of indices representing the North Atlantic Oscillation, the tropical Pacific Walker Circulation, and the Pacific–North American pattern are weak or non‐existent over the full period of record. The long‐term trends of zonally averaged precipitation minus evaporation also differ in character from those in climate model simulations of the twentieth century. Copyright © 2011 Royal Meteorological Society and Crown Copyright.

BACKGROUND: Observational cohort studies and a secondary prevention trial have shown inverse associations between adherence to the Mediterranean diet and cardiovascular risk. METHODS: In a multicenter trial in Spain, we assigned 7447 participants (55 to 80 years of age, 57% women) who were at high cardiovascular risk, but with no cardiovascular disease at enrollment, to one of three diets: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (advice to reduce dietary fat). Participants received quarterly educational sessions and, depending on group assignment, free provision of extra-virgin olive oil, mixed nuts, or small nonfood gifts. The primary end point was a major cardiovascular event (myocardial infarction, stroke, or death from cardiovascular causes). After a median follow-up of 4.8 years, the trial was stopped on the basis of a prespecified interim analysis. In 2013, we reported the results for the primary end point in the Journal. We subsequently identified protocol deviations, including enrollment of household members without randomization, assignment to a study group without randomization of some participants at 1 of 11 study sites, and apparent inconsistent use of randomization tables at another site. We have withdrawn our previously published report and now report revised effect estimates based on analyses that do not rely exclusively on the assumption that all the participants were randomly assigned. RESULTS: A primary end-point event occurred in 288 participants; there were 96 events in the group assigned to a Mediterranean diet with extra-virgin olive oil (3.8%), 83 in the group assigned to a Mediterranean diet with nuts (3.4%), and 109 in the control group (4.4%). In the intention-to-treat analysis including all the participants and adjusting for baseline characteristics and propensity scores, the hazard ratio was 0.69 (95% confidence interval [CI], 0.53 to 0.91) for a Mediterranean diet with extra-virgin olive oil and 0.72 (95% CI, 0.54 to 0.95) for a Mediterranean diet with nuts, as compared with the control diet. Results were similar after the omission of 1588 participants whose study-group assignments were known or suspected to have departed from the protocol. CONCLUSIONS: In this study involving persons at high cardiovascular risk, the incidence of major cardiovascular events was lower among those assigned to a Mediterranean diet supplemented with extra-virgin olive oil or nuts than among those assigned to a reduced-fat diet. (Funded by Instituto de Salud Carlos III, Spanish Ministry of Health, and others; Current Controlled Trials number, ISRCTN35739639 .).

In most natural and engineered systems, a set of entities interact with each other in complicated patterns that can encompass multiple types of relationships, change in time and include other types of complications. Such systems include multiple subsystems and layers of connectivity, and it is important to take such ‘multilayer’ features into account to try to improve our understanding of complex systems. Consequently, it is necessary to generalize ‘traditional’ network theory by developing (and validating) a framework and associated tools to study multilayer systems in a comprehensive fashion. The origins of such efforts date back several decades and arose in multiple disciplines, and now the study of multilayer networks has become one of the most important directions in network science. In this paper, we discuss the history of multilayer networks (and related concepts) and review the exploding body of work on such networks. To unify the disparate terminology in the large body of recent work, we discuss a general framework for multilayer networks, construct a dictionary of terminology to relate the numerous existing concepts to each other and provide a thorough discussion that compares, contrasts and translates between related notions such as multilayer networks, multiplex networks, interdependent networks, networks of networks and many others. We also survey and discuss existing data sets that can be represented as multilayer networks. We review attempts to generalize single-layer-network diagnostics to multilayer networks. We also discuss the rapidly expanding research on multilayer-network models and notions like community structure, connected components, tensor decompositions and various types of dynamical processes on multilayer networks. We conclude with a summary and an outlook.

We compare recent approaches to community structure identification in terms of sensitivity and computational cost. The recently proposed modularity measure is revisited and the performance of the methods as applied to ad hoc networks with known community structure, is compared. We find that the most accurate methods tend to be more computationally expensive, and that both aspects need to be considered when choosing a method for practical purposes. The work is intended as an introduction as well as a proposal for a standard benchmark test of community detection methods.

AIMS: The first aim was to critically evaluate the extent to which familial hypercholesterolaemia (FH) is underdiagnosed and undertreated. The second aim was to provide guidance for screening and treatment of FH, in order to prevent coronary heart disease (CHD). METHODS AND RESULTS: Of the theoretical estimated prevalence of 1/500 for heterozygous FH, <1% are diagnosed in most countries. Recently, direct screening in a Northern European general population diagnosed approximately 1/200 with heterozygous FH. All reported studies document failure to achieve recommended LDL cholesterol targets in a large proportion of individuals with FH, and up to 13-fold increased risk of CHD. Based on prevalences between 1/500 and 1/200, between 14 and 34 million individuals worldwide have FH. We recommend that children, adults, and families should be screened for FH if a person or family member presents with FH, a plasma cholesterol level in an adult ≥8 mmol/L(≥310 mg/dL) or a child ≥6 mmol/L(≥230 mg/dL), premature CHD, tendon xanthomas, or sudden premature cardiac death. In FH, low-density lipoprotein cholesterol targets are <3.5 mmol/L(<135 mg/dL) for children, <2.5 mmol/L(<100 mg/dL) for adults, and <1.8 mmol/L(<70 mg/dL) for adults with known CHD or diabetes. In addition to lifestyle and dietary counselling, treatment priorities are (i) in children, statins, ezetimibe, and bile acid binding resins, and (ii) in adults, maximal potent statin dose, ezetimibe, and bile acid binding resins. Lipoprotein apheresis can be offered in homozygotes and in treatment-resistant heterozygotes with CHD. CONCLUSION: Owing to severe underdiagnosis and undertreatment of FH, there is an urgent worldwide need for diagnostic screening together with early and aggressive treatment of this extremely high-risk condition.

AIMS: The aims of the study were, first, to critically evaluate lipoprotein(a) [Lp(a)] as a cardiovascular risk factor and, second, to advise on screening for elevated plasma Lp(a), on desirable levels, and on therapeutic strategies. METHODS AND RESULTS: The robust and specific association between elevated Lp(a) levels and increased cardiovascular disease (CVD)/coronary heart disease (CHD) risk, together with recent genetic findings, indicates that elevated Lp(a), like elevated LDL-cholesterol, is causally related to premature CVD/CHD. The association is continuous without a threshold or dependence on LDL- or non-HDL-cholesterol levels. Mechanistically, elevated Lp(a) levels may either induce a prothrombotic/anti-fibrinolytic effect as apolipoprotein(a) resembles both plasminogen and plasmin but has no fibrinolytic activity, or may accelerate atherosclerosis because, like LDL, the Lp(a) particle is cholesterol-rich, or both. We advise that Lp(a) be measured once, using an isoform-insensitive assay, in subjects at intermediate or high CVD/CHD risk with premature CVD, familial hypercholesterolaemia, a family history of premature CVD and/or elevated Lp(a), recurrent CVD despite statin treatment, ≥3% 10-year risk of fatal CVD according to European guidelines, and/or ≥10% 10-year risk of fatal + non-fatal CHD according to US guidelines. As a secondary priority after LDL-cholesterol reduction, we recommend a desirable level for Lp(a) <80th percentile (less than ∼50 mg/dL). Treatment should primarily be niacin 1-3 g/day, as a meta-analysis of randomized, controlled intervention trials demonstrates reduced CVD by niacin treatment. In extreme cases, LDL-apheresis is efficacious in removing Lp(a). CONCLUSION: We recommend screening for elevated Lp(a) in those at intermediate or high CVD/CHD risk, a desirable level <50 mg/dL as a function of global cardiovascular risk, and use of niacin for Lp(a) and CVD/CHD risk reduction.

For centuries, gold had been considered a precious, purely decorative inert metal. It was not until 1986 that Ito and Hayashi described the first application of gold(I) in homogeneous catalysis.(1) More than one decade later, the first examples of gold(I) activation of alkynes were reported by Teles(2) and Tanaka,(3) revealing the potential of gold(I) in organic synthesis. Now, gold(I) complexes are the most effective catalysts for the electrophilic activation of alkynes under homogeneous conditions, and a broad range of versatile synthetic tools have been developed for the construction of carbon–carbon or carbon–heteroatom bonds.\nGold(I) complexes selectively activate π-bonds of alkynes in complex molecular settings,(4-10) which has been attributed to relativistic effects.(11-13) In general, no other electrophilic late transition metal shows the breadth of synthetic applications of homogeneous gold(I) catalysts, although in occasions less Lewis acidic Pt(II) or Ag(I) complexes can be used as an alternative,(9, 10, 14, 15) particularly in the context of the activation of alkenes.(16, 17) Highly electrophilic Ga(III)(18-22) and In(III)(23, 24) salts can also be used as catalysts, although often higher catalyst loadings are required.\nIn general, the nucleophilic Markovnikov attack to η2-[AuL]+-activated alkynes 1 forms trans-alkenyl-gold complexes 2 as intermediates (Scheme 1).(4, 5a, 9, 10, 12, 25-29) This activation mode also occurs in gold-catalyzed cycloisomerizations of 1,n-enynes and in hydroarylation reactions, in which the alkene or the arene act as the nucleophile.\nfigure\nScheme 1. Anti-Nucleophilic Attack to η2-[AuL]+-Activated Alkynes\nStructurally, Au(I) predominantly forms linear two-coordinate complexes, although higher coordination numbers are also possible.(30) A significant number of alkyne-gold complexes have been characterized(31, 32) and studied either in solution(32, 33) or theoretically.(34) This selective activation of the alkyne moiety can explain a vast majority of the results experimentally observed for gold(I)-catalyzed cyclization of 1,n-enynes. Nevertheless, complexes of gold(I) with the alkene moiety of the enynes are also formed in equilibrium with the alkyne-gold complexes.(35) Indeed, well-characterized complexes of gold(I) with alkenes have been reported,(36) as well as with allenes(37) and 1,3-dienes.(38)\nDespite the fact that simple gold salts such as NaAuCl4 or AuCl are active enough to catalyze several transformations, gold(I) complexes bearing phosphines or N-heterocyclic carbenes as ligands have found more wide-ranging applications.(39) The active species are often generated in situ by chloride abstraction from [LAuCl] upon treatment with a silver salt bearing a weakly coordinating anion.\nComplexes [LAuY] only exist as neutral species when Y– is a coordinating anion (halides, carboxylates, sulfonates, and triflimide). The corresponding complexes with less coordinating anions, such as SbF6–, PF6–, or BF4–, are in most of the cases not stable. Although, species [AuL]+ (also known as “naked gold complexes”) are often suggested in mechanistic proposals, structural proof for their existence as stable, isolable species is still lacking. Here, for the sake of simplicity in mechanistic schemes throughout this review, LAu+ is used as a surrogate of [LAuL′]+ complexes, where L′ states for a relatively weakly bound ligand such as the substrate (alkyne or alkene), product, or solvent molecule.\nIt is important to remark that when the catalytically active species are generated in situ by chloride abstraction from complexes [LAuCl] in the absence of the alkyne or other unsaturated substrate, much less reactive chloride-bridged dinuclear species [LAuClAuL]Y are readily formed.(40) Formation of these dinuclear complexes could explain, at least partly, the erratic results that have been ascribed as the “silver effects” in reactions in which Ag(I) salts are used in situ to activate neutral gold(I) complexes [LAuY].(41)\nOften, the most convenient catalysts for the activation of alkynes are complexes [LAuL′]X or [LAuX] bearing weakly coordinating neutral (L′)(42) or anionic ligand (X–).(43) These complexes can enter catalytic cycles by ligand exchange with the unsaturated substrate, which proceed by associative mechanisms as observed for Au(I) and other diagonal d10 metal centers.(44) Thus, large negative activation entropies characteristic of associative mechanisms have been determined for the rate determining ligand exchange reactions of substituted alkyne(45, 46) and alkenes(36o) on commonly used Au(I) catalysts. Although nitriles are frequently used as weakly coordinating neutral ligands, 1,2,3-triazole(46, 47) or other related ligands(48) have also been employed.\nThe properties of gold(I) complexes can be easily tuned sterically or electronically depending on the ligand, consequently modulating their reactivity in the activation of alkynes, alkenes, and allenes.(27, 29f, 49) Thus, complexes containing more donating N-heterocyclic carbenes (3) are less electrophilic than those with phosphine ligands (4, 5) (Figure 1).(28) Complexes with less donating phosphite ligands (6) and related species are the most electrophilic catalysts.\nfigure\nFigure 1. Increase in electrophilicity with decreased donating ligand ability in gold(I) complexes.\n\nGold(I) complexes bearing weak-coordinated ligands such as Me2S, thiodiglycol, or tetrahydrothiophene (tht) have been widely used for the preparation of soluble gold(I) complexes, commonly starting from a gold(III) source.(50) Complex [Au(tmbn)2]SbF6 (tmbn = 2,4,6-trimethoxybenzonitrile), in which gold(I) is supported by two nitrile ligands, can be used for the in situ preparation of a variety of chiral and achiral cationic complexes [LAu(tmbn)]SbF6, including complexes immobilized on a polymeric support.(42a) Other immobilized gold(I) complexes have also been prepared.(51) The use of gold complexes bearing chiral ligands has led to the development of efficient asymmetric gold-catalyzed transformations.(52) Less common precatalysts used in gold(I)-catalyzed transformations are gold hydroxo complex IPrAuOH, which is activated in the presence of Brønsted acids,(53) open carbenes,(39c, 54) and other related complexes,(55) which give rise to selective catalysts of moderate electrophilicity. Cyclopropenylylidene-stabilized phospenium cations, which behave similarly to classical triaryl- and trialkylphosphines, have also been used as ligands in gold-catalyzed reactions.(56)\nThe effect of the counteranion has been studied in detail for several gold(I)-catalyzed transformations.(57, 58) Thus, for the intermolecular reaction of phenylacetylene with 2-methylstyrene catalyzed by [t-BuXPhosAu(NCMe)]Y, it was found that yields increase depending on the counteranion in the order Y = OTf– &lt; NTf2– &lt; BF4– &lt; SbF6– &lt; BARF (BARF = 3,5,bis(trifluoromethyl)phenylborate). By using the bulky and noncoordinating anion BARF, yields are increased by 10–30% compared to those obtained when Y = SbF6–, probably due to a decrease in the formation of the unproductive σ,π-(alkyne)digold(I) complexes from the initial alkyne.(57)\n1.2Scope and Organization of the Review\nHomogeneous gold(I)-catalysis has experienced an outbreak in the past decade leading to the discovery of a remarkable amount of new synthetically useful transformations. Thus, in recent years many groups have used gold catalysis in key steps of total synthesis taking advantage of the unique catalytic ability of gold to build molecular complexity under mild reaction conditions.\nSeveral reviews have been published on gold(I)-catalyzed reactions of alkynes, enynes, and related substrates,(5, 7, 25-28, 59) as well as on gold(I)-catalyzed reactions of allenes(60) and cascade gold-catalyzed reactions.(61) Moreover, specific reviews focused on gold-catalyzed carbon-heteroatom bond formation(62) and on the use of gold catalysis in total synthesis(63) have also been published. In this review, we will cover reactions of alkynes activated by gold(I) complexes, including recent applications of these transformations in the synthesis of natural products. According to the aim of this thematic issue, the main focus is on the application of gold(I)-catalyzed reactions of alkynes in organic synthesis, although reactions are organized mechanistically. Reactions of gold(I)-activated alkenes and allenes, as well as gold(III)-activated alkynes, will not be covered.\nThe discussion has been primarily organized based on the different reactions catalyzed by gold(I) complexes that alkynes can undergo. When possible, inter- and intramolecular processes, as well as the applications in total synthesis, are treated in specific subsections.

BACKGROUND: The Mediterranean diet has been shown to have beneficial effects on cardiovascular risk factors. OBJECTIVE: To compare the short-term effects of 2 Mediterranean diets versus those of a low-fat diet on intermediate markers of cardiovascular risk. DESIGN: Substudy of a multicenter, randomized, primary prevention trial of cardiovascular disease (Prevención con Dieta Mediterránea [PREDIMED] Study). SETTING: Primary care centers affiliated with 10 teaching hospitals. PARTICIPANTS: 772 asymptomatic persons 55 to 80 years of age at high cardiovascular risk who were recruited from October 2003 to March 2004. INTERVENTIONS: Participants were assigned to a low-fat diet (n = 257) or to 1 of 2 Mediterranean diets. Those allocated to Mediterranean diets received nutritional education and either free virgin olive oil, 1 liter per week (n = 257), or free nuts, 30 g/d (n = 258). The authors evaluated outcome changes at 3 months. MEASUREMENTS: Body weight, blood pressure, lipid profile, glucose levels, and inflammatory molecules. RESULTS: The completion rate was 99.6%. Compared with the low-fat diet, the 2 Mediterranean diets produced beneficial changes in most outcomes. Compared with the low-fat diet, the mean changes in the Mediterranean diet with olive oil group and the Mediterranean diet with nuts group were -0.39 mmol/L (95% CI, -0.70 to -0.07 mmol/L) and -0.30 mmol/L (CI, -0.58 to -0.01 mmol/L), respectively, for plasma glucose levels; -5.9 mm Hg (CI, -8.7 to -3.1 mm Hg) and -7.1 mm Hg (CI, -10.0 to -4.1 mm Hg), respectively, for systolic blood pressure; and -0.38 (CI, -0.55 to -0.22) and - 0.26 (CI, -0.42 to -0.10), respectively, for the cholesterol-high-density lipoprotein cholesterol ratio. The Mediterranean diet with olive oil reduced C-reactive protein levels by 0.54 mg/L (CI, 1.04 to 0.03 mg/L) compared with the low-fat diet. LIMITATIONS: This short-term study did not focus on clinical outcomes. Nutritional education about low-fat diet was less intense than education about Mediterranean diets. CONCLUSION: Compared with a low-fat diet, Mediterranean diets supplemented with olive oil or nuts have beneficial effects on cardiovascular risk factors.

Parallel analysis (PA) is an often-recommended approach for assessment of the dimensionality of a variable set. PA is known in different variants, which may yield different dimensionality indications. In this article, the authors considered the most appropriate PA procedure to assess the number of common factors underlying ordered polytomously scored variables. They proposed minimum rank factor analysis (MRFA) as an extraction method, rather than the currently applied principal component analysis (PCA) and principal axes factoring. A simulation study, based on data with major and minor factors, showed that all procedures consistently point at the number of major common factors. A polychoric-based PA slightly outperformed a Pearson-based PA, but convergence problems may hamper its empirical application. In empirical practice, PA-MRFA with a 95% threshold based on polychoric correlations or, in case of nonconvergence, Pearson correlations with mean thresholds appear to be a good choice for identification of the number of common factors. PA-MRFA is a common-factor-based method and performed best in the simulation experiment. PA based on PCA with a 95% threshold is second best, as this method showed good performances in the empirically relevant conditions of the simulation experiment.

We propose a method to find the community structure in complex networks based on an extremal optimization of the value of modularity. The method outperforms the optimal modularity found by the existing algorithms in the literature giving a better understanding of the community structure. We present the results of the algorithm for computer-simulated and real networks and compare them with other approaches. The efficiency and accuracy of the method make it feasible to be used for the accurate identification of community structure in large complex networks.

We propose a procedure for analyzing and characterizing complex networks. We apply this to the social network as constructed from email communications within a medium sized university with about 1700 employees. Email networks provide an accurate and nonintrusive description of the flow of information within human organizations. Our results reveal the self-organization of the network into a state where the distribution of community sizes is self-similar. This suggests that a universal mechanism, responsible for emergence of scaling in other self-organized complex systems, as, for instance, river networks, could also be the underlying driving force in the formation and evolution of social networks.

Abstract

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In this study, we present the collation and analysis of the gridded land‐based dataset of indices of temperature and precipitation extremes: HadEX2. Indices were calculated based on station data using a consistent approach recommended by the World Meteorological Organization (WMO) Expert Team on Climate Change Detection and Indices, resulting in the production of 17 temperature and 12 precipitation indices derived from daily maximum and minimum temperature and precipitation observations. High‐quality in situ observations from over 7000 temperature and 11,000 precipitation meteorological stations across the globe were obtained to calculate the indices over the period of record available for each station. Monthly and annual indices were then interpolated onto a 3.75° × 2.5° longitude‐latitude grid over the period 1901–2010. Linear trends in the gridded fields were computed and tested for statistical significance. Overall there was very good agreement with the previous HadEX dataset during the overlapping data period. Results showed widespread significant changes in temperature extremes consistent with warming, especially for those indices derived from daily minimum temperature over the whole 110 years of record but with stronger trends in more recent decades. Seasonal results showed significant warming in all seasons but more so in the colder months. Precipitation indices also showed widespread and significant trends, but the changes were much more spatially heterogeneous compared with temperature changes. However, results indicated more areas with significant increasing trends in extreme precipitation amounts, intensity, and frequency than areas with decreasing trends.

The design and use of materials in the nanoscale size range for addressing medical and health-related issues continues to receive increasing interest. Research in nanomedicine spans a multitude of areas, including drug delivery, vaccine development, antibacterial, diagnosis and imaging tools, wearable devices, implants, high-throughput screening platforms, etc. using biological, nonbiological, biomimetic, or hybrid materials. Many of these developments are starting to be translated into viable clinical products. Here, we provide an overview of recent developments in nanomedicine and highlight the current challenges and upcoming opportunities for the field and translation to the clinic.

Purpose – The aim of this paper is to present a sampling method using virtual networks to study “hard‐to‐reach” populations. In the ambit of social research, the use of new technologies is still questioned because the selection bias is an obstacle to carry on scientific research on the Internet. In this regard, the authors' hypothesis is that the use of social networking sites (Web 2.0) can be effective for the study of “hard‐to‐reach” populations. The main advantages of this technique are that it can expand the geographical scope and facilitates the identification of individuals with barriers to access. Therefore, the use of virtual networks in non‐probabilistic samples can increase the sample size and its representativeness.

Even at low-density lipoprotein cholesterol (LDL-C) goal, patients with cardiometabolic abnormalities remain at high risk of cardiovascular events. This paper aims (i) to critically appraise evidence for elevated levels of triglyceride-rich lipoproteins (TRLs) and low levels of high-density lipoprotein cholesterol (HDL-C) as cardiovascular risk factors, and (ii) to advise on therapeutic strategies for management. Current evidence supports a causal association between elevated TRL and their remnants, low HDL-C, and cardiovascular risk. This interpretation is based on mechanistic and genetic studies for TRL and remnants, together with the epidemiological data suggestive of the association for circulating triglycerides and cardiovascular disease. For HDL, epidemiological, mechanistic, and clinical intervention data are consistent with the view that low HDL-C contributes to elevated cardiovascular risk; genetic evidence is unclear however, potentially reflecting the complexity of HDL metabolism. The Panel believes that therapeutic targeting of elevated triglycerides (≥ 1.7 mmol/L or 150 mg/dL), a marker of TRL and their remnants, and/or low HDL-C (<1.0 mmol/L or 40 mg/dL) may provide further benefit. The first step should be lifestyle interventions together with consideration of compliance with pharmacotherapy and secondary causes of dyslipidaemia. If inadequately corrected, adding niacin or a fibrate, or intensifying LDL-C lowering therapy may be considered. Treatment decisions regarding statin combination therapy should take into account relevant safety concerns, i.e. the risk of elevation of blood glucose, uric acid or liver enzymes with niacin, and myopathy, increased serum creatinine and cholelithiasis with fibrates. These recommendations will facilitate reduction in the substantial cardiovascular risk that persists in patients with cardiometabolic abnormalities at LDL-C goal.