Needle-like structures discovered on positively charged lightning branches.

Lightning is a dangerous yet poorly understood natural phenomenon. Lightning forms a network of plasma channels propagating away from the initiation point with both positively and negatively charged ends-called positive and negative leaders1. Negative leaders propagate in discrete steps, emitting copious radio pulses in the 30-300-megahertz frequency band2-8 that can be remotely sensed and imaged with high spatial and temporal resolution9-11. Positive leaders propagate more continuously and thus emit very little high-frequency radiation12. Radio emission from positive leaders has nevertheless been mapped13-15, and exhibits a pattern that is different from that of negative leaders11-13,16,17. Furthermore, it has been inferred that positive leaders can become transiently disconnected from negative leaders9,12,16,18-20, which may lead to current pulses that both reconnect positive leaders to negative leaders11,16,17,20-22 and cause multiple cloud-to-ground lightning events1. The disconnection process is thought to be due to negative differential resistance18, but this does not explain why the disconnections form primarily on positive leaders22, or why the current in cloud-to-ground lightning never goes to zero23. Indeed, it is still not understood how positive leaders emit radio-frequency radiation or why they behave differently from negative leaders. Here we report three-dimensional radio interferometric observations of lightning over the Netherlands with unprecedented spatiotemporal resolution. We find small plasma structures-which we call 'needles'-that are the dominant source of radio emission from the positive leaders. These structures appear to drain charge from the leader, and are probably the reason why positive leaders disconnect from negative ones, and why cloud-to-ground lightning connects to the ground multiple times.

Ambient temperature and solar insolation are associated with decreased prevalence of SSRI-treated psychiatric disorders.

Serotonergic function is known to fluctuate in association with light and temperature. Serotonin-related behaviors and disorders similarly vary with climatic exposure, but the associations are complex. This complexity may reflect the importance of dose and timing of exposure, as well as acclimation. This cross-sectional study tests how average climate exposures (ambient temperature and solar insolation) vary with the prevalence of a group of SSRI-treated disorders. For comparison, we similarly studied a group of disorders not treated by SSRIs (i.e substance use disorders). Psychiatric prevalence data were obtained from the Collaborative Psychiatric Epidemiology Surveys (CPES). Average yearly solar insolation was obtained from NASA's NLDAS-2 Forcing Dataset Information. Average yearly temperature was obtained from NOAA's US Climate Normals. Logistic regression models were generated to assess the relationship between these two climatic factors and the prevalence of SSRI-treated and substance use disorders. Age, gender, race, income, and education were included in the models to control for possible confounding. Temperature and insolation were significantly associated with the SSRI-responsive group. For an average 1 GJ/m2/year increase, OR was 0.90 (95% CI 0.85-0.96, p = 0.001), and for an average 10 °F increase, OR was 0.93 (95% CI 0.88-0.97, p = 0.001). This relationship was not seen with substance use disorders (insolation OR: 0.97, p = 0.682; temperature OR: 0.96, p = 0.481). These results warrant further investigation, but they support the hypothesis that chronic exposure to increased temperature and light positively impact serotonin function, and are associated with reduced prevalence of some psychiatric disorders. They also support further investigation of light and hyperthermia treatments.

Climate change and landscape development in post-closure safety assessment of solid radioactive waste disposal: Results of an initiative of the IAEA.

The International Atomic Energy Agency has coordinated an international project addressing climate change and landscape development in post-closure safety assessments of solid radioactive waste disposal. The work has been supported by results of parallel on-going research that has been published in a variety of reports and peer reviewed journal articles. The project is due to be described in detail in a forthcoming IAEA report. Noting the multi-disciplinary nature of post-closure safety assessments, here, an overview of the work is given to provide researchers in the broader fields of radioecology and radiological safety assessment with a review of the work that has been undertaken. It is hoped that such dissemination will support and promote integrated understanding and coherent treatment of climate change and landscape development within an overall assessment process. The key activities undertaken in the project were: identification of the key processes that drive environmental change (mainly those associated with climate and climate change), and description of how a relevant future may develop on a global scale; development of a methodology for characterising environmental change that is valid on a global scale, showing how modelled global changes in climate can be downscaled to provide information that may be needed for characterising environmental change in site-specific assessments, and illustrating different aspects of the methodology in a number of case studies that show the evolution of site characteristics and the implications for the dose assessment models. Overall, the study has shown that quantitative climate and landscape modelling has now developed to the stage that it can be used to define an envelope of climate and landscape change scenarios at specific sites and under specific greenhouse-gas emissions assumptions that is suitable for use in quantitative post-closure performance assessments. These scenarios are not predictions of the future, but are projections based on a well-established understanding of the important processes involved and their impacts on different types of landscape. Such projections support the understanding of, and selection of, plausible ranges of scenarios for use in post-closure safety assessments.

Perioperative nutrition in elective gastrointestinal surgery--potential for improvement?

Nutritional concern is one of the most important issues to be addressed in the perioperative care given to gastrointestinal patients. Not at least, malnutrition may be detrimental and relate to postoperative morbidity. Perioperative nutritional management, integrated with other modern perioperative care policies, allows the establishment of multimodal strategies with an attempt to optimize the patients' course of disease. The present review evaluates available data regarding pre- and postoperative nutrition, nutritional supplements, including immunonutrition, and their clinical role. It is to be concluded that pre- and postoperative prolonged fasting has no routine role in management. Instead, for example, early postoperative feeding administered perorally or enterally may reduce postoperative complications and length of hospital stay. There are also indications that perioperative immunonutrition may reduce postoperative infectious complications and length of hospital stay, though further studies in this field are needed.

An overview of BORIS: Bioavailability of Radionuclides in Soils.

The ability to predict the consequences of an accidental release of radionuclides relies mainly on the level of understanding of the mechanisms involved in radionuclide interactions with different components of agricultural and natural ecosystems and their formalisation into predictive models. Numerous studies and databases on contaminated agricultural and natural areas have been obtained, but their use to enhance our prediction ability has been largely limited by their unresolved variability. Such variability seems to stem from incomplete knowledge about radionuclide interactions with the soil matrix, soil moisture, and biological elements in the soil and additional pollutants, which may be found in such soils. In the 5th European Framework Programme entitled Bioavailability of Radionuclides in Soils (BORIS), we investigated the role of the abiotic (soil components and soil structure) and biological elements (organic compounds, plants, mycorrhiza, and microbes) in radionuclide sorption/desorption in soils and radionuclide uptake/release by plants. Because of the importance of their radioisotopes, the bioavailability of three elements, caesium, strontium, and technetium has been followed. The role of one additional non-radioactive pollutant (copper) has been scrutinised in some cases. Role of microorganisms (e.g., K(d) for caesium and strontium in organic soils is much greater in the presence of microorganisms than in their absence), plant physiology (e.g., changes in plant physiology affect radionuclide uptake by plants), and the presence of mycorrhizal fungi (e.g., interferes with the uptake of radionuclides by plants) have been demonstrated. Knowledge acquired from these experiments has been incorporated into two mechanistic models CHEMFAST and BIORUR, specifically modelling radionuclide sorption/desorption from soil matrices and radionuclide uptake by/release from plants. These mechanistic models have been incorporated into an assessment model to enhance its prediction ability by introducing the concept of bioavailability factor for radionuclides.

Immunomodulation in surgical practice.

BACKGROUND: Immunomodulation may represent a potential way to improve surgical outcome. These types of interventions should be based on detailed knowledge of the underlying mechanisms involved. The aim of the present review is to summarize some experience on the acute phase response, potential ways of intervention and experiences from critical illness and HPB disease. DISCUSSION: Mechanisms of the acute phase response are discussed including the individual parameters and local changes that take part. Mechanisms involved in failure of the gut barrier are presented and include changes in gut barrier permeability, effects on gut-associated immunocompetent cells, and systemic implications. As examples of HPB disease, mechanisms of the acute phase response and potential ways of intervention in obstructive jaundice and acute pancreatitis are discussed. Nutritional pharmacology and lessons learned from immunomodulation and immunonutrition in critical illness and major abdominal surgery, including upper GI and HPB surgery, are referred to. Overall, immunomodulation represents a potential tool to improve results but requires a thorough mapping of underlying mechanisms in order to achieve individualized treatment or prevention based on patients' specific needs.

Treatment of acute asthma: salbutamol via jet nebuliser vs spacer and metered dose inhaler.

OBJECTIVE: To compare the efficacy of salbutamol delivered by jet nebuliser (JN) with salbutamol via a pressurised metered dose inhaler (PMDI) and a large volume spacer (Volumatic) for management of acute asthma. STUDY POPULATION: A total of 160 children aged from 4 to 12 years presenting to an Emergency Department with acute asthma. METHODS: The study was of multicentre (n=5) randomised, double blind, parallel design. Children weighing less than 25 kg received salbutamol 2.5 mg via the JN or 600 microg (six puffs) from the PMDI. Children over 25 kg received salbutamol 5 mg via the JN or 1200 microg (12 puffs) via the PMDI. Clinical score (range 0-12) and PEF (over 7 years) were recorded at baseline and 15, 30, 45 and 60 mins post administration. RESULTS: The improvement from baseline at 30 min in the clinical score was 1.87 for JN and 1.43 for PMDI (P=0.09) and at 60 min was 2.15 for JN and 1.12 for PMDI (P=0.0001). The improvement in PEF at 30 min was 51 L min(-1) for JN and 27 L min(-1) for PMDI (P=0.0007) and at 60 min was 57 L min(-1) for JN and 31.5 L min(-1) for PMDI (P=0.001). CONCLUSION: Administration of salbutamol via a PMDI and a large volume spacer device provides effective relief in the management of acute asthma in children, but to a lesser extent than a jet nebuliser. This difference may represent a dose response effect.

Improved preservation of rat hindlimbs with the University of Wisconsin solution and butanedione monoxime.

The purpose of this study was to compare the effects of the University of Wisconsin solution plus butanedione monoxime, the University of Wisconsin solution without butanedione monoxime, and saline on the preservation of muscle tissue. Forty-nine rat hindlimbs were amputated and replanted. The study population was subdivided into four groups according to flushing solution, storage, and replantation protocols. The limbs of the control group (n = 12) were flushed with 20 ml University of Wisconsin solution and immediately replanted onto the same rat. In the remaining three groups, the limbs were immersed in solution, stored in a refrigerator at 4 degrees C for 24 hours, and then replanted onto a fresh rat. The limbs in the no flushout group (n = 7) were placed into storage in cold saline solution without being flushed. The limbs in the University of Wisconsin solution group (n = 17) were flushed with 20 ml of University of Wisconsin solution prior to storage, and those in the University of Wisconsin solution plus butanedione monoxime group (n = 13) were flushed with 20 ml University of Wisconsin solution plus 20 mM butanedione monoxime. Limb survival rate was 100 percent for the control and University of Wisconsin solution plus butanedione monoxime groups, 87 percent for the University of Wisconsin solution group, and 71 percent for the no flushout group. Seven days after replantation, ATP levels were 71 percent of control in the University of Wisconsin solution plus butanedione monoxime group, 33 percent in the University of Wisconsin solution group, and 29 percent in the no flushout group. Tissue K+/Na+ ratio showed that the University of Wisconsin solution plus butanedione monoxime group maintained electrolyte balance, whereas the balance was significantly lowered in University of Wisconsin solution and no flushout groups. The University of Wisconsin solution plus butanedione monoxime limbs did not exhibit cell swelling, whereas total tissue water values for the University of Wisconsin solution and no flushout groups increased significantly. Serum creatinine kinase, measured 24 hours after replantation, was 120 percent of control in the University of Wisconsin solution plus butanedione monoxime group, 550 percent in the University of Wisconsin solution group, and 772 percent in the no flushout group. Limbs in the University of Wisconsin solution plus butanedione monoxime group had more flexible ankle joints and pliable muscle (i.e., less contracture) than those in the University of Wisconsin solution and no flushout groups. In conclusion, rat hindlimbs can be preserved hypothermically for 24 hours using the University of Wisconsin solution, the University of Wisconsin solution plus butanedione monoxime, or saline. However, the University of Wisconsin solution plus butanedione monoxime limbs had better ATP levels and less cellular injury after replantation. Based on these results, we believe that, biochemically, flushing and storage of muscle tissue in the University of Wisconsin solution plus butanedione monoxime are the most effective means of those studied for preserving composite tissue grafts for 24 hours.

Europium complexation by an aquatic fulvic acid - effects of competing ions.

Effects of competing ions, Fe (2+)Fe (3+) and Al(3+), on Eu(3+) complexation with an aquatic fulvic acid (FA), have been investigated using an ion exchange technique. The influence of different concentrations (10(-6), 10(-4) M) of the competing ions on the distribution coefficient for Eu was measured, and the overall complex formation function, beta(ov), was resolved for the Eu systems with Fe and Al. All systems showed pH-dependent beta(ov)-functions. The presence of 10(-4) M concentration of competing ion reduced the resolved complex formation function (logbeta(ov)) for Eu complexation with fulvic acid by 0.6 and 0.4 log units at pH 5 for Fe and Al, respectively. this indicates that Fe has a more perturbing effect on Eu-FA complexation than Al. In similar competition studies Sr and Eu were found not to perturb each others complexation with fulvic acid, suggesting therefore that the two metals probably bind to different sites on the fulvic acid molecule.

Characterization of humic substances using capillary electrophoresis with photodiode array and laser-induced fluorescence detection.

The effect of organic modifiers (organic solvents and urea) on the electrophoretic buffer was investigated in an attempt to enhance resolution in the finger-printing of two humic substances (HS): an aquatic fulvic acid (FA) and a soil humic acid (HA). Two detection modes, photodiode array and laser-induced fluorescence, were applied. The addition of organic solvents (acetonitrile, acetone, 2-propanol and tetrahydrofuran) in 10 mM Na2B4O7 (pH 9.0) resulted in a clear difference in electrophoretic behavior of the studied HS compared to the absence of organic solvents. There were also marked differences in the electrophoretic profiles using a 2-propanol-borate buffer with urea. The study of the interaction between metals and HS showed that there was a change in the migration pattern in the presence of A1(III), indicating the specific binding sites of aluminum.

Rapid susceptibility testing for nontuberculosis mycobacteria using flow cytometry.

We demonstrated previously that susceptibility testing of Mycobacterium tuberculosis could be accomplished within 24 h after the organisms were incubated with antituberculosis agents by using fluorescein diacetate (FDA) staining and flow cytometry. Continued studies have now shown that assay suspensions containing M. avium, M. fortuitum, M. gordonae, or M. marinum incubated with various concentrations of ciprofloxacin, clarithromycin, erythromycin, kanamycin, rifampin, tobramycin hydrolyzed less FDA than drug-free controls. Suspensions of treated and nontreated mycobacteria could be easily differentiated at 6 and 24 h after the initiation of the susceptibility assays by using FDA staining and flow cytometry. In addition, multiplication of the mycobacteria was not required to discern differences between drug-free suspensions of mycobacteria and those treated with antimycobacterial agents. The flow cytometric assay is simple, reproducible, and rapid.

Whose life is it anyway? A study in respect for autonomy.

Brian Clark's drama, Whose Life Is It Anyway?, explores the difficulties of applying the principle of respect for autonomy to real-life circumstances. In the play a permanently disabled patient, who wishes to be allowed to die, raises moral questions about the adequacy of the autonomous agent, respect for the autonomy of others, the authority of the law, the allocation of society's resources, and the intrinsic value of human life. After a brief review of the story and definition of respect for autonomy, this paper cites passages from the play that dramatize the tension between respect for autonomy and these other moral concerns. There follows a review of relevant commentary from the classicists Kant and Mill and the modernists Childress and Gillon. The study concludes that although classical and contemporary philosophers have clarified and elaborated upon the relationship between ethical principles, they have not provided definitive guidelines.

Rapid susceptibility testing of Mycobacterium tuberculosis (H37Ra) by flow cytometry.

The resurgence of tuberculosis has caused considerable effort to be focused on the development of rapid methods for determining the susceptibility of Mycobacterium tuberculosis to antimycobacterial agents. We demonstrated that susceptibility testing of M. tuberculosis can be accomplished rapidly by using flow cytometry. Results of tests were available within 24 h after M. tuberculosis organisms were incubated with ethambutol, isoniazid, rifampin, or streptomycin. The method was based on the ability of viable M. tuberculosis organisms to hydrolyze fluorescein diacetate (FDA) and the detection of fluorescent mycobacteria by flow cytometric analysis. The assay system also did not require multiplication of the mycobacteria. In contrast, M. tuberculosis organisms exposed to antimycobacterial agents hydrolyzed significantly less FDA. The use of flow cytometry and FDA staining shows considerable promise as a rapid method for obtaining susceptibility test results.

Predictors of survival for infants with congenital diaphragmatic hernia.

Over the past decade, the survival rate of infants with congenital diaphragmatic hernia (CDH) treated in the intensive care unit of the Royal Children's Hospital, Melbourne, has remained unchanged at 56% +/- 6%. Newer forms of treatment, such as extracorporeal membrane oxygenation (ECMO), high-frequency oscillation, and surfactant and nitric oxide therapy, are now available. The exact role of these therapies in the management of infants with CDH has not been determined. This study examines five clinical parameters derived from an infant's best preoperative ventilatory and blood gas data in the first 24 hours of life. One hundred twenty-five CDH infants were admitted to the intensive care unit between January 1, 1981 and December 31, 1991. Criteria for inclusion in the study were (1) CDH diagnosed within 6 hours of delivery, (2) ventilation before repair, and (3) no associated lethal congenital abnormality. Of the 90 cases studied in detail, there were 38 deaths (42% mortality rate). All five parameters were analyzed by receiver operating curve analysis to determine the optimum value of each parameter in predicting survival. An oxygenation index (MAP x FIO2/PaO2) of less than 0.08 predicted a 94% chance of survival, with a sensitivity of 96% and a specificity of 95%. Similarly, a modified ventilation index (PIP x RR x CO2/1,000) of less than 40 predicted a 91% chance of survival, with a sensitivity of 94% and a specificity of 86%. By stratifying each criterion according to outcome, three groups of infants were identified according to their response to conventional therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical analysis of dorsal plate fixation in proximal phalangeal fractures.

The biomechanical properties of three minifragment plate and screw systems were compared to determine whether plate systems primarily designed for maxillofacial reconstruction are biomechanically sound for use in proximal phalangeal fracture fixation. A middiaphyseal transverse osteotomy was created in each of 30 fresh-frozen human proximal phalanges to simulate an unstable fracture. Each osteotomy was then fixed with four 2.0ml screws through one of three different four-hole minifragment plates in a middorsal position. Plating systems tested included a vitallium plate with self-tapping screws (Luhr), a stainless steel plate with tapped screws (Synthes), and a titanium plate with tapped screws (Synthes). Testing was performed to failure in an apex volar three-point bending mode. The titanium-plated phalanges were the stiffest construct and required the greatest load and total energy absorbed to failure. However, only the load to failure for titanium versus stainless steel was significantly different. Therefore, there is no biomechanical disadvantage to using the titanium or vitallium plate and screw systems in the setting of unstable proximal phalangeal fractures.

The binding of strontium and europium by an aquatic fulvic acid--ion exchange distribution and ultrafiltration studies.

The complexation of an aquatic fulvic acid, FA, with Sr(2+) and Eu(3+) was studied at 0.10 and O1.O1M NaClO(4) using trace levels of metal ([Sr(2+)] = 10(-9)M and [Eu(3+)] = 10(-11)M) and a constant FA concentration (0.12 g/l) by an ultrafiltration technique (UF) and an ion exchange distribution method (IEDS). The overall complex formation function, beta(OV) for the two metals was calculated and its dependence on pH, ionic strength and method was investigated. The absolute value of log beta(OV), the pH dependence and the influence of the ionic strength on the complexation differed depending on the metal ion and experimental technique employed. By considering the functional group heterogeneity of the FA molecule, it was possible to predict the most predominantly bound site (keto-enol) and resolve the complex formation function for this site and EU(3+) (IEDS: 9.43 +/- 0.29 l/eq at 0.10M and 10.58 +/- 0.72 l/eq at 0.01M; UF: 7.19 +/- 1.51 l/eq at 0.01M and 6.88 +/- 0.91 l/eq at 0.01M). The results are discussed in the light of possible intrinsic problems of the two experimental methods.