The influence of exposure to ultraviolet radiation in simulated sunlight on ascospores causing Black Sigatoka disease of banana and plantain

 The influence of ultraviolet (UV) radiation in simulated natural sunlight on the viability of ascospores of Mycosphaerella fijiensis, the cause of Black Sigatoka disease in banana and plantain, has been investigated as part of a study to assess the windborne spread of this pathogen from mainland Central and South America into the Caribbean. Spores were killed following continuous exposure to UV radiation for periods of 6 h or over. This relatively short exposure time suggests that the distances over which viable spores can be transported will be determined not only by the speed of the wind but also the amount of cloud cover and the time off day that spore release occurs. On this basis, wind dispersal of viable spores over distances greater than a few hundred kilometres is unlikely. These conclusions are reinforced by an examination of historical reports of the arrival of the disease in previously uninfected areas of the Americas and Africa. Received: 10 February 1997 / Accepted: 30 March 1998     

Closing the larval loop: linking larval ecology to the population dynamics of marine benthic invertebrates

The majority of marine benthic invertebrates exhibit a complex life cycle that includes separate planktonic larval, and bottom-dwelling juvenile and adult phases. To understand and predict changes in the spatial and temporal distributions, abundances, population growth rate, and population structure of a species with such a complex life cycle, it is necessary to understand the relative importance of the physical, chemical and biological properties and processes that affect individuals within both the planktonic and benthic phases. To accomplish this goal, it is necessary to study both phases within a common, quantitative framework defined in terms of some common currency. This can be done efficiently through construction and evaluation of a population dynamics model that describes the complete life cycle.

Two forms that such a model might assume are reviewed: a stage-based, population matrix model, and a model that specifies discrete stages of the population, on the bottom and in the water column, in terms of simultaneous differential equations that may be solved in both space and time. Terms to be incorporated in each type of model can be formulated to describe the critical properties and processes that can affect populations within each stage of the life cycle. For both types of model it is shown how this might be accomplished using an idealized balanomorph barnacle as an example species. The critical properties and processes that affect the planktonic and benthic phases are reviewed. For larvae, these include benthic adult fecundity and fertilization success, growth and larval stage duration, mortality, larval behavior, dispersal by currents and turbulence, and larval settlement. It is possible to predict or estimate empirically all of the key terms that should be built into the larval and benthic components of the model. Thus, the challenge of formulating and evaluating a full life cycle model is achievable. Development and evaluation of such a model will be challenging because of the diverse processes which must be considered, and because of the disparities in the spatial and temporal scales appropriate to the benthic and planktonic larval phases. In evaluating model predictions it is critical that sampling schemes be matched to the spatial and temporal scales of model resolution.     

Change in myocardial function after resuscitated sudden cardiac arrest and its impact on long-term mortality and defibrillator implantation

BackgroundThe impact of left ventricular ejection fraction (LVEF) changes after sudden cardiac arrest (SCA) on implantable defibrillator (ICD) utilization and long-term survival is not known. We therefore evaluated the influence of LVEF on these parameters in SCA survivors.MethodsData were collected on consecutive SCA survivors who had ≥1 echocardiogram after SCA and who survived to hospital discharge (n = 655). The median time from baseline to first follow-up echocardiogram was 162 days. LVEF ≥50% was defined as normal. Patients were classified into 4 groups according to baseline (LVEFb) and follow-up (LVEFf) myocardial function: normal LVEFb and LVEFf (group1, n = 261); reduced LVEFb and normal LVEFf (group 2, n = 104); normal LVEFb but reduced LVEFf (group 3, n = 41); and reduced LVEFb and LVEFf (group 4, n = 249). All-cause mortality and time to ICD implantation were examined in all groups.ResultsOver a median follow up of 4.3 years, death occurred in 279 (42%) of patients. Compared with patients in group 1, patients with any reduced LVEF at any time (groups 2–4) had significantly higher mortality, even after adjusting for unbalanced covariates (HR = 1.44, 95.0% CI 1.05–1.95, p = 0.022). ICDs were most commonly implanted in patients with persistently reduced LVEF (group 4: HR = 1.72, 95% CI = 1.26–2.35, p = 0.001).ConclusionWe demonstrate that, in survivors of SCA, a reduced LVEF at or after the index event is associated with higher mortality but that patients with persistently reduced LVEF were most likely to receive ICD therapy. These findings have implications on the management of SCA survivors.     

Impact of COVID-19 outbreak on hospital admissions and outcome of acute coronary syndromes in a single high-volume centre in southeastern Europe

BackgroundAs coronavirus disease 2019 (COVID-19) has reached pandemic status, authors from the most severely affected countries have reported reduced rates of hospital admissions for patients with acute coronary syndrome (ACS).AimThe aim of the present study was to investigate the influence of the COVID-19 outbreak on hospital admissions and outcomes in ACS patients in a single high-volume centre in southeastern Europe.MethodsThis retrospective observational study aimed to investigate the number of hospital admissions for ACS, clinical findings at admission, length of hospitalisation, major complications and in-hospital mortality during the COVID-19 outbreak and to compare the data with the same parameters during an equivalent time frame in 2019. For the ST-elevated myocardial infarction (STEMI) subgroup of patients, changes in ischaemic times were analysed as well.ResultsThere was a significant reduction of 44.3% in the number of patients admitted for ACS during the COVID-19 outbreak when compared with the same period in 2019 (151 vs 271; 95% confidence interval 38.4–50.2, p < 0.01) with a higher mortality rate (13.2% vs 7.2%, p = 0.03). In 2020, patients with non-ST-elevated myocardial infarction presented more often with acute heart failure (3.3% vs 0.7%, p = 0.04). During the COVID-19 outbreak, we observed increases in the total ischaemic time (303 ± 163.4 vs 200.8 ± 156.8 min, p < 0.05) and door-to-balloon time (69.2 ± 58.4 vs 50.5 ± 31.3 min, p < 0.01) in STEMI patients.ConclusionsThese findings should increase the awareness of morbidity and mortality related to missed or delayed treatment of ACS among the public and the healthcare services.     

The effect of cold and heat waves on mortality in Urmia a cold region in the North West of Iran

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Ecology of some species of catfishSynodontis (Pisces: Mochocidae) in the Kpong Headpond in Ghana

Synopsis Some aspects of the ecology of the freshwater catfishSynodontis (Pisces: Mochocidae) in Kpong Headpond (Ghana) were studied. Five species were encountered, namelySynodontis schall, S. gambiensis, S. ocellifer, S. velifer andS. eupterus. S. ocellifer andS. velifer were not recorded in the area before impoundment and might have entered the headpond as eggs or young from the main Volta Lake. Length: weight relationships for the two most important species can be described by the equations: Log W = - 1.76 + 3.12log L (maleS. schall), Log W = -1.33 + 2.89log L (femaleS. schall) and Log W = - 0.39 + 2.07log L (S. gambiensis, sexes combined).Synodontis is omnivorous and generally browses on benthic deposits. Adults feed mostly on chironomids, plant material and aquatic insects. The genus displays sexual dimorphism by having a short urino-genital papilla in most adult males. ForS. schall, one season of major spawning activity occurs per year from mid to late September with first time spawners between 20.0–30.0 cm SL. TheSynodontis species studied lay between 2000 to 209000 eggs per spawning season.     

Phenotypic plasticity and optimal timing of metamorphosis under uncertain time constraints

Life-history theory suggests that optimal timing of metamorphosis should depend on growth conditions and time constraints under which individuals develop. Current models cannot make reliable predictions for species in ephemeral habitats where individuals often face an increasing mortality risk over time because these models assume time-invariant mortality rates (i.e., daily mortality rates remain constant) and fixed seasons. We examined the plasticity of growth, development, and body mass at metamorphosis in tadpoles of the tree-hole breeding frog Phrynobatrachus guineensis in relation to an unpredictable time constraint in the field and in controlled experiments along a fixed density and food gradient. Mean mass and age at metamorphosis of sibships were positively correlated with per capita food level. Based on our results, we developed a simple model of the optimal timing of metamorphosis under time-dependent mortality rates showing that development rates are not only adjusted to growth conditions but also to time-variant mortality rates. The increasing mortality rate represents a time constraint that favors a reduced larval period, but because it is based on probabilities of survival it allows a trade-off between development time and mass. We extend this model to different types of time constraints and show that it can predict the range of documented reaction norms. Differences between species in␣the correlation of age and mass at metamorphosis may have evolved due to differences in their time-variant mortality rates.     

Functional evaluation of culture filtrates of Bacillus subtilis and Pseudomonas fluorescens on the mortality and hatching of Meloidogyne javanica

Rhizospheric bacteria Bacillus subtilis and Pseudomonas fluorescens are two widely tested biological control agents against root-knot nematodes (RKN) of different crops. However, their performance as bio-control agents varies with their place of origin. Culture filtrates of rhizospheric bacteria contain some intermediary metabolites that have nematicidal activity. An in vitro experiment was undertaken to evaluate the functionality of culture filtrates of B. subtilis (MN252542.1) and P. fluorescens (MN256394.1) at different concentrations (1.0%, 2.5%, 5.0%, 7.0%, 10.0% and 25.0%) on the hatching and mortality of Meloidogyne javanica at different time span. Bacterial strains were isolated from rhizospheric soils of Bangladesh. At three days after incubation (DAI), 25.0% concentration of culture filtrates of both B. subtilis and P. fluorescens showed 100.0% mortality of second stage juveniles (J₂) of M. javanica. Additionally, 25.0% concentration of culture filtrates of both bacteria showed 100.0% inhibition of hatching at one week after incubation (WAI). A decreasing trend in hatching of M. javanica was observed with the increment of the concentration of culture filtrates and progression of incubation time. The findings of this experiment reveal that culture filtrates of these accessions of B. subtilis and P. fluorescens are effective for controlling M. javanica and would be potential candidates for developing bio-nematicides.     

Assessment of intergravel conditions influencing egg and alevin survival during salmonid redd dewatering

Synopsis Extensive water use may alter stream flows so that areas used by salmonids for spawning are dewatered, thus exposing intergravel developmental phases to suddenly changed physical and chemical conditions. Environmental alteration may result in considerable mortality, particularly of the more vulnerable post-hatch phases. Five documented case histories of redd dewatering are reviewed. The primary conditions in the gravel that influence survival during dewatering are residual flow, moisture retention, temperature, gravel composition, dissolved oxygen, alevin behavior, and species characteristics. These factors are discussed and their complex relationships are evaluated. Considerable variation in intergravel conditions can be expected during dewatering at different locations. Onsite studies are needed to obtain data for assessment of potential impacts in other dewatering situations, and for development of effective mitigation procedures.     

Reseña: «¡Vergüenza! El escándalo de las residencias». Manuel Rico, 2020

Manuel Rico has written a book in which he takes a very rigorous approach to what happened in nursing homes during the COVID-19 pandemic. The text is built on the data and testimonies of agents involved in one way or another in what happened. This review aims to offer an approach to the most important data, conclusions and ideas, trying to maintain the investigative discipline that Rico maintains.