Science.gov

Sample records for experimental evidence indicating

  1. Pursuing Quality Evidence: Applying Single-Subject Quality Indicators to Non-Experimental Qualitative Educational Research

    ERIC Educational Resources Information Center

    Stodden, Robert A.; Yamamoto, Kathryn K.; Folk, Eric; Kong, Eran; Otsuji, Derek N.

    2013-01-01

    The need for quality evidence in support of strategies used while working with persons with autism and intellectual disability (ID) has been long been recognized by researchers and practitioners. The authors reviewed and applied a number of evidence-based indicators, developed through the "What Works Clearinghouse" (WWC), to the conduct…

  2. Pursuing Quality Evidence: Applying Single-Subject Quality Indicators to Non-Experimental Qualitative Educational Research

    ERIC Educational Resources Information Center

    Stodden, Robert A.; Yamamoto, Kathryn K.; Folk, Eric; Kong, Eran; Otsuji, Derek N.

    2013-01-01

    The need for quality evidence in support of strategies used while working with persons with autism and intellectual disability (ID) has been long been recognized by researchers and practitioners. The authors reviewed and applied a number of evidence-based indicators, developed through the "What Works Clearinghouse" (WWC), to the conduct…

  3. Verb Form Indicates Discourse Segment Type in Biological Research Papers: Experimental Evidence

    ERIC Educational Resources Information Center

    de Waard, Anita; Maat, Henk Pander

    2012-01-01

    Corpus studies suggest that verb tense is a differentiating feature between, on the one hand, text pertaining to experimental results (involving methods and results) and on the other hand, text pertaining to more abstract concepts (i.e. regarding background knowledge in a field, hypotheses, problems or claims). In this paper, we describe a user…

  4. Experimental evidence indicating that mastreviruses probably did not co-diverge with their hosts

    PubMed Central

    Harkins, Gordon W; Delport, Wayne; Duffy, Siobain; Wood, Natasha; Monjane, Adérito L; Owor, Betty E; Donaldson, Lara; Saumtally, Salem; Triton, Guy; Briddon, Rob W; Shepherd, Dionne N; Rybicki, Edward P; Martin, Darren P; Varsani, Arvind

    2009-01-01

    Background Despite the demonstration that geminiviruses, like many other single stranded DNA viruses, are evolving at rates similar to those of RNA viruses, a recent study has suggested that grass-infecting species in the genus Mastrevirus may have co-diverged with their hosts over millions of years. This "co-divergence hypothesis" requires that long-term mastrevirus substitution rates be at least 100,000-fold lower than their basal mutation rates and 10,000-fold lower than their observable short-term substitution rates. The credibility of this hypothesis, therefore, hinges on the testable claim that negative selection during mastrevirus evolution is so potent that it effectively purges 99.999% of all mutations that occur. Results We have conducted long-term evolution experiments lasting between 6 and 32 years, where we have determined substitution rates of between 2 and 3 × 10-4 substitutions/site/year for the mastreviruses Maize streak virus (MSV) and Sugarcane streak Réunion virus (SSRV). We further show that mutation biases are similar for different geminivirus genera, suggesting that mutational processes that drive high basal mutation rates are conserved across the family. Rather than displaying signs of extremely severe negative selection as implied by the co-divergence hypothesis, our evolution experiments indicate that MSV and SSRV are predominantly evolving under neutral genetic drift. Conclusion The absence of strong negative selection signals within our evolution experiments and the uniformly high geminivirus substitution rates that we and others have reported suggest that mastreviruses cannot have co-diverged with their hosts. PMID:19607673

  5. Reanalysis and experimental evidence indicate that the earliest trace fossil of a winged insect was a surface-skimming neopteran.

    PubMed

    Marden, James H

    2013-01-01

    A recent description and analysis of an imprint fossil from the Carboniferous concluded that it was made by a mayfly landing in sediment at the edge of water. Here, I reanalyze that trace fossil and supply experimental evidence regarding wing traces and behavior. The thorax of the trace maker lacked structures characteristic of mayflies, but closely matches a modern neopteran insect family (Taeniopterygidae, Plecoptera) little changed from Early Permian fossils. Edges of the folded wings of live Taeniopteryx leave marks on sediment closely matching marks in the trace fossil. Faint marks lateral to and beyond the reach of meso- and metathoracic legs match the location where wings of surface-skimming Taeniopteryx stoneflies lightly touch the sediment when these insects skim onto wet ground at shorelines. Dimensions of the thorax of the trace indicate relatively weak flight ability compared to fossils from the Early Permian, making doubtful the hypothesis that the trace maker was flight capable. Ultimately, this fossil best fits a scenario in which a neopteran insect skimmed across the surface of water, then folded its wings. Surface skimming as a precursor to the evolution of flight in insects is supported by this fossil evidence of skimming behavior in a Carboniferous insect. © 2012 The Author. Evolution© 2012 The Society for the Study of Evolution.

  6. Communicating Uncertain Experimental Evidence

    ERIC Educational Resources Information Center

    Davis, Alexander L.; Fischhoff, Baruch

    2014-01-01

    Four experiments examined when laypeople attribute unexpected experimental outcomes to error, in foresight and in hindsight, along with their judgments of whether the data should be published. Participants read vignettes describing hypothetical experiments, along with the result of the initial observation, considered as either a possibility…

  7. Communicating Uncertain Experimental Evidence

    ERIC Educational Resources Information Center

    Davis, Alexander L.; Fischhoff, Baruch

    2014-01-01

    Four experiments examined when laypeople attribute unexpected experimental outcomes to error, in foresight and in hindsight, along with their judgments of whether the data should be published. Participants read vignettes describing hypothetical experiments, along with the result of the initial observation, considered as either a possibility…

  8. Experimental Evidence for the Pentaquark

    SciTech Connect

    D.S. Carman

    2005-02-01

    The present experimental evidence for the existence of light pentaquarks is reviewed, including both positive and null results. I also discuss the CLAS experiments at Jefferson Laboratory that are forthcoming in the near future to address questions regarding existence, mass, width, and other quantum numbers of these five-quark baryon states.

  9. Facial expressions and speech acts: experimental evidences on the role of the upper face as an illocutionary force indicating device in language comprehension.

    PubMed

    Domaneschi, Filippo; Passarelli, Marcello; Chiorri, Carlo

    2017-08-01

    Language scientists have broadly addressed the problem of explaining how language users recognize the kind of speech act performed by a speaker uttering a sentence in a particular context. They have done so by investigating the role played by the illocutionary force indicating devices (IFIDs), i.e., all linguistic elements that indicate the illocutionary force of an utterance. The present work takes a first step in the direction of an experimental investigation of non-verbal IFIDs because it investigates the role played by facial expressions and, in particular, of upper-face action units (AUs) in the comprehension of three basic types of illocutionary force: assertions, questions, and orders. The results from a pilot experiment on production and two comprehension experiments showed that (1) certain upper-face AUs seem to constitute non-verbal signals that contribute to the understanding of the illocutionary force of questions and orders; (2) assertions are not expected to be marked by any upper-face AU; (3) some upper-face AUs can be associated, with different degrees of compatibility, with both questions and orders.

  10. Evidence-based indications for hindfoot endoscopy.

    PubMed

    Spennacchio, Pietro; Cucchi, Davide; Randelli, Pietro S; van Dijk, Niek C

    2016-04-01

    The 2-portal hindfoot endoscopic technique with the patient in prone position, first introduced by van Dijk et al. (Arthroscopy 16:871-876, 2000), is currently the most used by foot and ankle surgeons to address endoscopically pathologies located in the hindfoot. This article aims to review the literature to provide a comprehensive description of the level of evidence available to support the use of the 2-portal hindfoot endoscopy technique for the current generally accepted indications. A comprehensive review was performed by use of the PubMed database to isolate literature that described therapeutic studies investigating the results of different hindfoot endoscopy treatment techniques. All articles were reviewed and assigned a classification (I-V) of level of evidence. An analysis of the literature reviewed was used to assign a grade of recommendation for each current generally accepted indication for hindfoot endoscopy. A subscale was used to further describe the evidence base for indications receiving a grade of recommendation indicating poor-quality evidence. On the basis on the available evidence, posterior ankle impingement syndrome, subtalar arthritis and retrocalcaneal bursitis have the strongest recommendation in favour of treatment (grade Cf). Although a low level of evidence of the included studies, the review showed that adequate literature to support the use of the 2-portal endoscopic techniques for most currently accepted indications exists. Future "higher quality" evidence could strengthen current recommendations and further help surgeons in evidence-based practice. Level V, Review of Level III, IV and V studies.

  11. Comment on Marden (2013): "reanalysis and experimental evidence indicate that the earliest trace fossil of a winged insect was a surface skimming neopteran".

    PubMed

    Benner, Jacob S; Knecht, Richard J; Engel, Michael S

    2013-07-01

    Marden's (2013) reanalysis of Knecht et al. (2011) suggesting that specimen SEMC-F97 is the result of the skimming behavior of a neopteran insect and, more importantly, fossil evidence of "… surface skimming as a precursor to the evolution of flight in insects" (Marden 2013) is found to be deficient on three fronts: (1) the principal specimen was never viewed firsthand which led to significant morphological misinterpretations; (2) poorly designed and executed neoichnological experiments led to incredulous results; and (3) the assumption that this specimen is fossil evidence supporting the surface skimming hypothesis of the origin of insect flight despite the fact that since its induction into the literature that hypothesis has been refuted based on significant paleontological, phylogenetic, genetic, and developmental evidence.

  12. Experimental evidence of oxygen thermo-migration in PWR UO2 fuels during power ramps using in-situ oxido-reduction indicators

    NASA Astrophysics Data System (ADS)

    Riglet-Martial, Ch.; Sercombe, J.; Lamontagne, J.; Noirot, J.; Roure, I.; Blay, T.; Desgranges, L.

    2016-11-01

    The present study describes the in-situ electrochemical modifications which affect irradiated PWR UO2 fuels in the course of a power ramp, by means of in-situ oxido-reduction indicators such as chromium or neo-formed chemical phases. It is shown that irradiated fuels (of nominal stoichiometry close to 2.000) under temperature gradient such as that occurring during high power transients are submitted to strong oxido-reduction perturbations, owing to radial migration of oxygen from the hot center to the cold periphery of the pellet. The oxygen redistribution, similar to that encountered in Sodium Fast Reactors fuels, induces a massive reduction/precipitation of the fission products Mo, Ru, Tc and Cr (if present) in the high temperature pellet section and the formation of highly oxidized neo-formed grey phases of U4O9 type in its cold section, of lower temperature. The parameters governing the oxidation states of UO2 fuels under power ramps are finally debated from a cross-analysis of our results and other published information. The potential chemical benefits brought by oxido-reductive additives in UO2 fuel such as chromium oxide, in connection with their oxygen buffering properties, are discussed.

  13. [Indication for total knee arthroplasty: evidence mapping].

    PubMed

    Haase, Elisabeth; Lange, Toni; Lützner, Jörg; Kopkow, Christian; Petzold, Thomas; Günther, Klaus-Peter; Schmitt, Jochen

    2015-01-01

    Joint replacement surgery is one of the most often performed routine procedures for the treatment of knee osteoarthritis in Germany. Currently, there is no consensus on indication criteria for total knee arthroplasty (TKA). The topic indication for TKA was processed using six guiding questions concerning: 1) Common practice in determining the indication for TKA; 2) Inclusion criteria in clinical trials; 3) Treatment goals/goal criteria; 4) Predictors for goal attainment; 5) Economic aspects of determining a TKA indication; 6) Guidelines of the "Working Group of Scientific Medical Societies" (AWMF) in other areas. The evidence mapping was conducted by systematically searching Medline via Ovid, the Cochrane Library, through hand searching national guidelines and selected journals as well as the AWMF guideline portal. 1) In Germany there is currently no consented guideline regarding indications for TKA surgery. 2) Indication criteria for clinical trials are: diagnosed osteoarthritis of the knee, limitations of age and BMI. The most common criteria for exclusion include rheumatoid/inflammatory arthritis, secondary diagnoses and allergies. 3) As yet, no international initiatives have been identified which, by involving all relevant stakeholders, have reached consensus regarding the indication criteria for TKA. 4) A variety of predictors were identified with effects on individual treatment goals acting in different directions. 5) Very few studies were identified concerning economic aspects of determining TKA indication. 6) Comparable AWMF guidelines are currently not available. The findings of this study suggest that specific systematic reviews are needed to explore the following questions: What are the treatment goals of a TKA intervention? For whom are these relevant? And how are they measured? Continuous analyses are recommended in the field of predictors for a positive TKA outcome. Copyright © 2015. Published by Elsevier GmbH.

  14. Epidemiological evidence indicates asbestos causes laryngeal cancer

    SciTech Connect

    Smith, A.H.; Handley, M.A.; Wood, R. )

    1990-06-01

    A variety of opinions have been expressed in the literature concerning asbestos and laryngeal cancer. This paper presents an analysis of epidemiological studies based on criteria that prioritized the most heavily exposed cohorts. Emphasis was given to the six cohorts or subcohorts with lung cancer relative risk estimates of 2 or more. The two groups of workers with the highest lung cancer relative risk estimates (4.06 and 3.28) both gave strong support for a causal association of asbestos and laryngeal cancer, with relative risk estimates of 1.91 (90% confidence limits 1.00 to 3.34) and 3.75 (90% confidence limits 1.01 to 9.68), respectively. Confounding with cigarette smoking or alcohol consumption does not explain the findings. Case-control studies gave mixed results, but generally supported the hypothesis. It was concluded that asbestos is a probable cause of laryngeal cancer in view of the reasonable consistency of the studies, the strength of the association in key studies, the evidence for dose-response relationships, and the biological plausibility for asbestos being a cause of laryngeal cancer. 48 references.

  15. Experimental evidence of the compressibility of arteries.

    PubMed

    Yosibash, Zohar; Manor, Itay; Gilad, Ilan; Willentz, Udi

    2014-11-01

    A definitive answer to the question whether artery walls are incompressible is to our opinion not yet categorically provided. Experimental-based evidence on the level of compressibility in artery walls is not easily achieved because of the difficulties associated with the measurement of very small differences in volumes under physiological pressure in these biological tissues. Past experiments aimed at addressing the question considered different species, different arteries, the experimental devices were not accurate enough and a statistical analysis of the results was missing. A precise experimental device together with a thorough testing protocol, a careful selection of arteries and a statistical analysis is presented for a definitive evaluation of the artery wall compressibility. We provide experimental evidence that in saphenous and femoral porcine arteries under physiological pressure range a relative compressibility of 2-6% is observed. The pre-assumption of incompressibility in many phenomenological constitutive models of artery walls should probably be re-evaluated.

  16. Experimental evidence for Abraham pressure of light

    NASA Astrophysics Data System (ADS)

    Zhang, Li; She, Weilong; Peng, Nan; Leonhardt, Ulf

    2015-05-01

    The question of how much momentum light carries in media has been debated for over a century. Two rivalling theories, one from 1908 by Hermann Minkowski and the other from 1909 by Max Abraham, predict the exact opposite when light enters an optical material: a pulling force in Minkowski's case and a pushing force in Abraham's. Most experimental tests have agreed with Minkowski's theory, but here we report the first quantitative experimental evidence for Abraham's pushing pressure of light. Our results matter in optofluidics and optomechanics, and wherever light exerts mechanical pressure.

  17. Antiatherogenic properties of metformin: the experimental evidence.

    PubMed

    Mamputu, J C; Wiernsperger, N F; Renier, G

    2003-09-01

    Cardiovascular disease (CVD) is the major determining factor of morbidity and mortality in type 2 diabetic patients. The established relationship between type 2 diabetes and atherosclerosis has fueled suggestions that anti-diabetic drugs with beneficial effects on CV risk factors may help attenuate the atherosclerotic process in diabetic patients. Metformin is a hypoglycaemic agent widely used in the management of type 2 diabetes. In addition to its insulin-sensitising action, this drug has favourable effects on various CV risk factors and reduces macrovascular complications in obese type 2 diabetic patients. This review summarises in vivo and in vitro experimental evidence on the antiatherogenic properties of metformin.

  18. Experimental Evidence on Iterated Reasoning in Games.

    PubMed

    Grehl, Sascha; Tutić, Andreas

    2015-01-01

    We present experimental evidence on two forms of iterated reasoning in games, i.e. backward induction and interactive knowledge. Besides reliable estimates of the cognitive skills of the subjects, our design allows us to disentangle two possible explanations for the observed limits in performed iterated reasoning: Restrictions in subjects' cognitive abilities and their beliefs concerning the rationality of co-players. In comparison to previous literature, our estimates regarding subjects' skills in iterated reasoning are quite pessimistic. Also, we find that beliefs concerning the rationality of co-players are completely irrelevant in explaining the observed limited amount of iterated reasoning in the dirty faces game. In addition, it is demonstrated that skills in backward induction are a solid predictor for skills in iterated knowledge, which points to some generalized ability of the subjects in iterated reasoning.

  19. The support of human genetic evidence for approved drug indications.

    PubMed

    Nelson, Matthew R; Tipney, Hannah; Painter, Jeffery L; Shen, Judong; Nicoletti, Paola; Shen, Yufeng; Floratos, Aris; Sham, Pak Chung; Li, Mulin Jun; Wang, Junwen; Cardon, Lon R; Whittaker, John C; Sanseau, Philippe

    2015-08-01

    Over a quarter of drugs that enter clinical development fail because they are ineffective. Growing insight into genes that influence human disease may affect how drug targets and indications are selected. However, there is little guidance about how much weight should be given to genetic evidence in making these key decisions. To answer this question, we investigated how well the current archive of genetic evidence predicts drug mechanisms. We found that, among well-studied indications, the proportion of drug mechanisms with direct genetic support increases significantly across the drug development pipeline, from 2.0% at the preclinical stage to 8.2% among mechanisms for approved drugs, and varies dramatically among disease areas. We estimate that selecting genetically supported targets could double the success rate in clinical development. Therefore, using the growing wealth of human genetic data to select the best targets and indications should have a measurable impact on the successful development of new drugs.

  20. Experimental evidence of electromagnetic pollution of ionosphere

    NASA Astrophysics Data System (ADS)

    Pronenko, Vira; Korepanov, Valery; Dudkin, Denis

    multiple low orbiting satellites have confirmed a significant increase in their intensity over the populated areas of Europe and Asia. Recently, there are many experimental evidences of the existence of power line harmonic radiation (PLHR) in the ionosphere. Their spectra consist of succession of 50 (60) Hz harmonics which is accompanied by a set of lines separated by 50 (60) or 100 (120) Hz - the central frequency of which is shifted to high frequency. These lines cover rather wide band - according to the available experimental data, their central frequencies are observed from ~1.5 - 3 kHz up to 15 kHz, and recently the main mains frequencies are also observed. The examples of power line harmonic radiation, which were detected by “Sich-1M”, “Chibis-M” and “Demeter” satellites, have been presented and discussed. The available experimental data, as well as theoretical estimations, allow us with a high degree of certainty to say that the permanent satellite monitoring of the ionospheric and magnetospheric anthropogenic EM perturbations is necessary for: a) objective assessment and prediction of the space weather conditions; b) evaluation of the daily or seasonal changes in the level of energy consumption; c) construction of a map for estimation of near space EM pollution. This study is partially supported by SSAU contract N 4-03/13.

  1. Experimental evidence of the Frenkel line in supercritical neon

    NASA Astrophysics Data System (ADS)

    Prescher, C.; Fomin, Yu. D.; Prakapenka, V. B.; Stefanski, J.; Trachenko, K.; Brazhkin, V. V.

    2017-04-01

    Recent research suggests that the supercritical state consists of liquidlike and gaslike states where particle dynamics and key system properties are qualitatively different. We report experimental evidence of the structural crossover in supercritical neon at pressure and temperature conditions significantly exceeding the critical point values: 250 Pc and 6.6 Tc . The experimental results show a crossover of the medium-range order structure evidenced by the change of the structure factor with pressure. We also observe the crossover of the short-range order structure indicated by changes in the coordination number. The relative width of the crossover is fairly narrow and is smaller than 10-12% in pressure and temperature. By comparing our experimental results with molecular dynamics simulations, we suggest that the observed crossover can be attributed to the Frenkel line and discuss the relationship between the structural crossover and qualitative changes of dynamical and thermodynamic properties of supercritical matter.

  2. Expert opinions and scientific evidence for colonoscopy key performance indicators

    PubMed Central

    Rees, Colin J; Bevan, Roisin; Zimmermann-Fraedrich, Katharina; Rutter, Matthew D; Rex, Douglas; Dekker, Evelien; Ponchon, Thierry; Bretthauer, Michael; Regula, Jaroslaw; Saunders, Brian; Hassan, Cesare; Bourke, Michael J; Rösch, Thomas

    2016-01-01

    Colonoscopy is a widely performed procedure with procedural volumes increasing annually throughout the world. Many procedures are now performed as part of colorectal cancer screening programmes. Colonoscopy should be of high quality and measures of this quality should be evidence based. New UK key performance indicators and quality assurance standards have been developed by a working group with consensus agreement on each standard reached. This paper reviews the scientific basis for each of the quality measures published in the UK standards. PMID:27802153

  3. Experimental evidence for Efimov quantum states

    NASA Astrophysics Data System (ADS)

    Naegerl, Hanns-Christoph

    2006-05-01

    Three interacting particles form a system which is well known for its complex physical behavior. A landmark theoretical result in few-body quantum physics is Efimov's prediction of a universal set of weakly bound trimer states appearing for three identical bosons with a resonant two-body interaction [1]. Surprisingly, these states even exist in the absence of a corresponding two-body bound state and their precise nature is largely independent of the concrete type of the two-body interaction potential. Efimov's scenario has attracted great interest in many areas of physics; an experimental test however has not been achieved. We report the observation of an Efimov resonance in an ultracold thermal gas of cesium atoms [2]. The resonance occurs in the range of large negative two-body scattering lengths and arises from the coupling of three free atoms to an Efimov trimer. We observe its signature as a giant three-body recombination loss when the strength of the two-body interaction is varied near a Feshbach resonance. We also report on a minimum in the recombination loss for positive scattering lengths, indicating destructive interference of decay pathways. Our results confirm central theoretical predictions of Efimov physics and represent a starting point with which to explore the universal properties of resonantly interacting few-body systems. [1] V. Efimov, Phys. Lett. 33B, 563 (1970). [2] T. Kraemer, M. Mark, P. Waldburger, J. G. Danzl, C. Chin, B. Engeser, A. D. Lange, K. Pilch, A. Jaakkola, H.-C. N"agerl, R. Grimm, accepted for publication in Nature, cond-mat/0512394.

  4. Expert opinions and scientific evidence for colonoscopy key performance indicators.

    PubMed

    Rees, Colin J; Bevan, Roisin; Zimmermann-Fraedrich, Katharina; Rutter, Matthew D; Rex, Douglas; Dekker, Evelien; Ponchon, Thierry; Bretthauer, Michael; Regula, Jaroslaw; Saunders, Brian; Hassan, Cesare; Bourke, Michael J; Rösch, Thomas

    2016-12-01

    Colonoscopy is a widely performed procedure with procedural volumes increasing annually throughout the world. Many procedures are now performed as part of colorectal cancer screening programmes. Colonoscopy should be of high quality and measures of this quality should be evidence based. New UK key performance indicators and quality assurance standards have been developed by a working group with consensus agreement on each standard reached. This paper reviews the scientific basis for each of the quality measures published in the UK standards. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  5. Experimental Evidence of Chaos from Memristors

    NASA Astrophysics Data System (ADS)

    Gambuzza, Lucia Valentina; Fortuna, Luigi; Frasca, Mattia; Gale, Ella

    Until now, most memristor-based chaotic circuits proposed in the literature are based on mathematical models which assume ideal characteristics such as piecewise-linear or cubic nonlinearities. The idea, illustrated here and originating from the experimental approach for device characterization, is to realize a chaotic system exploiting the nonlinearity of only one memristor with a very simple experimental set-up using feedback. In this way, a simple circuit is obtained and chaos is experimentally observed and is confirmed by the calculation of the largest Lyapunov exponent. Numerical results using the Strukov model support the existence of robust chaos in our circuit. To our knowledge, this is the first experimental demonstration of chaos in a real memristor circuit and suggests that memristors are well placed for hardware encryption.

  6. Indications for tonsillectomy stratified by the level of evidence

    PubMed Central

    Windfuhr, Jochen P.

    2016-01-01

    Background: One of the most significant clinical trials, demonstrating the efficacy of tonsillectomy (TE) for recurrent throat infection in severely affected children, was published in 1984. This systematic review was undertaken to compile various indications for TE as suggested in the literature after 1984 and to stratify the papers according to the current concept of evidence-based medicine. Material and methods: A systematic Medline research was performed using the key word of “tonsillectomy“ in combination with different filters such as “systematic reviews“, “meta-analysis“, “English“, “German“, and “from 1984/01/01 to 2015/05/31“. Further research was performed in the Cochrane Database of Systematic Reviews, National Guideline Clearinghouse, Guidelines International Network and BMJ Clinical Evidence using the same key word. Finally, data from the “Trip Database” were researched for “tonsillectomy” and “indication“ and “from: 1984 to: 2015“ in combination with either “systematic review“ or “meta-analysis“ or “metaanalysis”. Results: A total of 237 papers were retrieved but only 57 matched our inclusion criteria covering the following topics: peritonsillar abscess (3), guidelines (5), otitis media with effusion (5), psoriasis (3), PFAPA syndrome (6), evidence-based indications (5), renal diseases (7), sleep-related breathing disorders (11), and tonsillitis/pharyngitis (12), respectively. Conclusions: 1) The literature suggests, that TE is not indicated to treat otitis media with effusion. 2) It has been shown, that the PFAPA syndrome is self-limiting and responds well to steroid administration, at least in a considerable amount of children. The indication for TE therefore appears to be imbalanced but further research is required to clarify the value of surgery. 3) Abscesstonsillectomy as a routine is not justified and indicated only for cases not responding to other measures of treatment, evident complications

  7. [Key performance indicators of OR efficiency. Myths and evidence of key performance indicators in OR management].

    PubMed

    Schuster, M; Wicha, L L; Fiege, M

    2007-03-01

    A variety of different key performance indicators, both for process and financial performance, are used to evaluate OR efficiency. Certain indicators like OR utilization and turnover times seem to become common standard in many hospitals to evaluate OR process performance. Despite the general use and availability of these indicators in OR management, the scientific evidence behind these data is relatively low. These process indicators are strongly influenced by artefacts and depend on planning process, resource allocation and documentation. Direct financial indicators become more important with increasing autonomy of OR management. Besides budgetary compliance the focus is set on the net results of internal transfer pricing systems. By taking part in an internal transfer pricing system, OR management develops from a mere passive cost center to an active shaper of perioperative processes. However, detailed knowledge of the origin of costs and pitfalls of internal transfer pricing systems is crucial. The increased transparency due to the free accessibility of diagnosis-related-groups (DRG) cost breakdown data can help to develop tools for economic analysis of OR efficiency.

  8. Natural compounds as anticancer agents: Experimental evidence

    PubMed Central

    Wang, Jiao; Jiang, Yang-Fu

    2012-01-01

    Cancer prevention research has drawn much attention worldwide. It is believed that some types of cancer can be prevented by following a healthy life style. Cancer chemoprevention by either natural or synthetic agents is a promising route towards lowering cancer incidence. In recent years, the concept of cancer chemoprevention has evolved greatly. Experimental studies in animal models demonstrate that the reversal or suppression of premalignant lesions by chemopreventive agents is achievable. Natural occurring agents such as dietary phytochemicals, tea polyphenols and resveratrol show chemopreventive activity in animal models. Moreover, clinical trials for testing the safety and efficacy of a variety of natural agents in preventing or treating human malignancy have been ongoing. Here, we summarize experimental data on the chemopreventive or tumor suppressive effects of several natural compounds including curcumin, (-)-epigallocatechin-3-gallate, resveratrol, indole-3-carbinol, and vitamin D. PMID:24520533

  9. Experimental evidence against middle ear oxygen absorption.

    PubMed

    Buckingham, R A; Stuart, D R; Geick, M R; Girgis, S J; McGee, T J

    1985-04-01

    The present theory of eustachian tube (ET) function and middle ear (ME) ventilation posits that oxygen absorbed by the ME mucosa causes negative ME pressure which is relieved by periodic opening of the ET during swallowing and yawning. After developing a method to cannulate the ET of mongrel dogs we connected the cannulas hermetically to manometers. This system excluded ET function and tested the oxygen absorption capacity of the ME. When we controlled respiration and maintained blood gas PO2 and PCO2 at normal levels, we were unable to find any manometric evidence of negative pressure of gas absorption in the dog ME. Lowering the PCO2 and raising the PO2 of the blood by hyperventilation caused negative ME pressure which could be measured manometrically. We confirmed these findings with the tympanometer. Raising the PCO2 and lowering the PO2 by hypoventilation caused positive pressure in the ME. There is no evidence in these experiments that O2 absorption occurs or causes negative ME pressure in the dog. To the contrary there is evidence that elevated blood levels of the more diffusible CO2 cause an increase in the ME pressure and lowered CO2 level causes a negative ME pressure.

  10. Experimental Evidence for a Wave Cosmology

    NASA Astrophysics Data System (ADS)

    Wagner, Orvin

    1997-04-01

    I have previously reported (see Wagner Web Site) slow moving, charge and matter separating, longitudinal waves, threading through matter and space. The waves I report are apparently produced by oscillating sources such as the sun and the planets, electromagnetic sources, and experimentally using electromagnetic sources. Experimentally the excited wavelengths are found to be close to the dimensions of the electromagnetic source regardless of its frequency. Oscillations of these waves can explain the solar cycle and determine planet and other satellite locations: r=r0exp(0.625N) where N is an integer for a particular planet or satellite of a planet and r0 is the radius of the sun or planet when the satellites were placed. This equation describes waves that are speeding up as the density of the medium (dark matter?) decreases moving away from the source. These waves are found experimentally to produce standing waves around any source apparently due to special reflection from the medium. These observations are consistent with the idea that these waves produce a pattern around a star with matter tending to collect only at specific locations(N) to produce satellites.

  11. [Progesterone for Prevention of Preterm Birth--Evidence-based Indications].

    PubMed

    Kuon, R-J; Abele, H; Berger, R; Garnier, Y; Maul, H; Schleußner, E; Rath, W

    2015-06-01

    The prevention and treatment of preterm birth remains an unsolved problem in modern obstetrics. Progesterone has a variety of actions on the myometrium and the cervix, among others inhibition of myometrial contractility and a cervix strengthening effect by inhibiting the production of proinflammatory cytokines and prostaglandins as well as by reducing the synthesis of proteins, which play a crucial role in initiating labour. Consequently, progesterone may be a promising candidate for the prevention of preterm birth. We searched PubMed from 1956 to August 2014 using a combination of key words and text words related to preterm birth and progesterone. ('progesterone', progestins, 17-OHPC). The aim of the literature search was to determine evidence-based indications for the use of progesterone in the prevention of preterm birth. (i) Patients with a singleton pregnancy and history of preterm birth should receive vaginal progesterone daily (200 mg capsule or 90 mg containing gel) from 16+0 to 36+0 weeks of gestation (alternatively 250 mg intramuscular 17-OHPC weekly): level of evidence 1a, grade of recommendation ++ . Prophylactic progesterone reduces the incidence of preterm birth <34 and <37 weeks of gestation and perinatal mortality significantly. (ii) Patients with singleton pregnancies and a sonographically short cervix (≤25 mm) before 24 weeks of gestation should receive vaginal progesterone daily (200 mg capsule or 90 mg containing gel) until 36+6 weeks of gestation: level of evidence 1a, grade of recommendation ++ . Prophylactic progesterone leads to a significant reduction in the incidence of preterm birth <28, <33, and <35 weeks of gestation and is associated with a significant reduction of neonatal morbidity. (III) There is a lack of evidence to recommend vaginal progesterone or intramuscular 17-OHPC for primary tocolysis or for "adjunctive" tocolysis (in combination with conventional tocolytic agents). (IV) There is a growing body of

  12. Experimental Evidence for Quantum Tunneling Time

    NASA Astrophysics Data System (ADS)

    Camus, Nicolas; Yakaboylu, Enderalp; Fechner, Lutz; Klaiber, Michael; Laux, Martin; Mi, Yonghao; Hatsagortsyan, Karen Z.; Pfeifer, Thomas; Keitel, Christoph H.; Moshammer, Robert

    2017-07-01

    The first hundred attoseconds of the electron dynamics during strong field tunneling ionization are investigated. We quantify theoretically how the electron's classical trajectories in the continuum emerge from the tunneling process and test the results with those achieved in parallel from attoclock measurements. An especially high sensitivity on the tunneling barrier is accomplished here by comparing the momentum distributions of two atomic species of slightly deviating atomic potentials (argon and krypton) being ionized under absolutely identical conditions with near-infrared laser pulses (1300 nm). The agreement between experiment and theory provides clear evidence for a nonzero tunneling time delay and a nonvanishing longitudinal momentum of the electron at the "tunnel exit."

  13. Evidence for gammacerane as an indicator of water column stratification

    NASA Technical Reports Server (NTRS)

    Sinninghe Damste, J. S.; Kenig, F.; Koopmans, M. P.; Koster, J.; Schouten, S.; Hayes, J. M.; de Leeuw, J. W.

    1995-01-01

    A new route for the formation of gammacerane from tetrahymanol is proposed; in addition to dehydration and hydrogenation, sulphurisation and early C-S cleavage are shown to be important in the pathway of formation, especially in marine sediments. Evidence is twofold. First, relatively large amounts of the gammacerane skeleton are sequestered in S-rich macromolecular aggregates formed by natural sulphurisation of functionalised lipids. Selective cleavage of polysulphide linkages with MeLi/MeI led to formation of 3-methylthiogammacerane, indicating that the gammacerane skeleton is primarily bound via sulphur at position 3, consistent with the idea that tetrahymanol (or the corresponding ketone) is the precursor for gammacerane. Second, upon mild artificial maturation of two sediments using hydrous pyrolysis, gammacerane is released from S-rich macromolecular aggregates by cleavage of the relatively weak C-S bonds. The stable carbon isotopic compositions of gammacerane and lipids derived from primary producers and green sulphur bacteria in both the Miocene Gessoso-solfifera and Upper Jurassic Allgau Formations indicate that gammacerane is derived from bacterivorous ciliates which were partially feeding on green sulphur bacteria. This demonstrates that anaerobic ciliates living at or below the chemocline are important sources for gammacerane, consistent with the fact that ciliates only biosynthesize tetrahymanol if their diet is deprived of sterols. This leads to the conclusion that gammacerane is an indicator for water column stratification, which solves two current enigmas in gammacerane geochemistry. Firstly, it explains why gammacerane is often found in sediments deposited under hypersaline conditions but is not necessarily restricted to this type of deposits. Secondly, it explains why lacustrine deposits may contain abundant gammacerane since most lakes in the temperate climatic zones are stratified during summer.

  14. Evidence for gammacerane as an indicator of water column stratification

    NASA Astrophysics Data System (ADS)

    Sinninghe Damsté, Jaap S.; Kenig, Fabien; Koopmans, Martin P.; Köster, Jürgen; Schouten, Stefan; Hayes, J. M.; de Leeuw, Jan W.

    1995-05-01

    A new route for the formation of gammacerane from tetrahymanol is proposed; in addition to dehydration and hydrogenation, sulphurisation and early CS cleavage are shown to be important in the pathway of formation, especially in marine sediments. Evidence is twofold. First, relatively large amounts of the gammacerane skeleton are sequestered in S-rich macromolecular aggregates formed by natural sulphurisation of functionalised lipids. Selective cleavage of polysulphide linkages with MeLi/MeI led to formation of 3-methylthiogammacerane, indicating that the gammacerane skeleton is primarily bound via sulphur at position 3, consistent with the idea that tetrahymanol (or the corresponding ketone) is the precursor for gammacerane. Second, upon mild artificial maturation of two sediments using hydrous pyrolysis, gammacerane is released from S-rich macromolecular aggregates by cleavage of the relatively weak CS bonds. The stable carbon isotopic compositions of gammacerane and lipids derived from primary producers and green sulphur bacteria in both the Miocene Gessoso-solfifera and Upper Jurassic Allgäu Formations indicate that gammacerane is derived from bacterivorous ciliates which were partially feeding on green sulphur bacteria. This demonstrates that anaerobic ciliates living at or below the chemocline are important sources for gammacerane, consistent with the fact that ciliates only biosynthesize tetrahymanol if their diet is deprived of sterols. This leads to the conclusion that gammacerane is an indicator for water column stratification, which solves two current enigmas in gammacerane geochemistry. Firstly, it explains why gammacerane is often found in sediments deposited under hypersaline conditions but is not necessarily restricted to this type of deposits. Secondly, it explains why lacustrine deposits may contain abundant gammacerane since most lakes in the temperate climatic zones are stratified during summer.

  15. Evidence for gammacerane as an indicator of water column stratification

    NASA Technical Reports Server (NTRS)

    Sinninghe Damste, J. S.; Kenig, F.; Koopmans, M. P.; Koster, J.; Schouten, S.; Hayes, J. M.; de Leeuw, J. W.

    1995-01-01

    A new route for the formation of gammacerane from tetrahymanol is proposed; in addition to dehydration and hydrogenation, sulphurisation and early C-S cleavage are shown to be important in the pathway of formation, especially in marine sediments. Evidence is twofold. First, relatively large amounts of the gammacerane skeleton are sequestered in S-rich macromolecular aggregates formed by natural sulphurisation of functionalised lipids. Selective cleavage of polysulphide linkages with MeLi/MeI led to formation of 3-methylthiogammacerane, indicating that the gammacerane skeleton is primarily bound via sulphur at position 3, consistent with the idea that tetrahymanol (or the corresponding ketone) is the precursor for gammacerane. Second, upon mild artificial maturation of two sediments using hydrous pyrolysis, gammacerane is released from S-rich macromolecular aggregates by cleavage of the relatively weak C-S bonds. The stable carbon isotopic compositions of gammacerane and lipids derived from primary producers and green sulphur bacteria in both the Miocene Gessoso-solfifera and Upper Jurassic Allgau Formations indicate that gammacerane is derived from bacterivorous ciliates which were partially feeding on green sulphur bacteria. This demonstrates that anaerobic ciliates living at or below the chemocline are important sources for gammacerane, consistent with the fact that ciliates only biosynthesize tetrahymanol if their diet is deprived of sterols. This leads to the conclusion that gammacerane is an indicator for water column stratification, which solves two current enigmas in gammacerane geochemistry. Firstly, it explains why gammacerane is often found in sediments deposited under hypersaline conditions but is not necessarily restricted to this type of deposits. Secondly, it explains why lacustrine deposits may contain abundant gammacerane since most lakes in the temperate climatic zones are stratified during summer.

  16. Experimental evidence for circular inference in schizophrenia

    NASA Astrophysics Data System (ADS)

    Jardri, Renaud; Duverne, Sandrine; Litvinova, Alexandra S.; Denève, Sophie

    2017-01-01

    Schizophrenia (SCZ) is a complex mental disorder that may result in some combination of hallucinations, delusions and disorganized thinking. Here SCZ patients and healthy controls (CTLs) report their level of confidence on a forced-choice task that manipulated the strength of sensory evidence and prior information. Neither group's responses can be explained by simple Bayesian inference. Rather, individual responses are best captured by a model with different degrees of circular inference. Circular inference refers to a corruption of sensory data by prior information and vice versa, leading us to `see what we expect' (through descending loops), to `expect what we see' (through ascending loops) or both. Ascending loops are stronger for SCZ than CTLs and correlate with the severity of positive symptoms. Descending loops correlate with the severity of negative symptoms. Both loops correlate with disorganized symptoms. The findings suggest that circular inference might mediate the clinical manifestations of SCZ.

  17. Experimental Evidence for Quantum Tunneling Time.

    PubMed

    Camus, Nicolas; Yakaboylu, Enderalp; Fechner, Lutz; Klaiber, Michael; Laux, Martin; Mi, Yonghao; Hatsagortsyan, Karen Z; Pfeifer, Thomas; Keitel, Christoph H; Moshammer, Robert

    2017-07-14

    The first hundred attoseconds of the electron dynamics during strong field tunneling ionization are investigated. We quantify theoretically how the electron's classical trajectories in the continuum emerge from the tunneling process and test the results with those achieved in parallel from attoclock measurements. An especially high sensitivity on the tunneling barrier is accomplished here by comparing the momentum distributions of two atomic species of slightly deviating atomic potentials (argon and krypton) being ionized under absolutely identical conditions with near-infrared laser pulses (1300 nm). The agreement between experiment and theory provides clear evidence for a nonzero tunneling time delay and a nonvanishing longitudinal momentum of the electron at the "tunnel exit."

  18. Experimental evidence for circular inference in schizophrenia

    PubMed Central

    Jardri, Renaud; Duverne, Sandrine; Litvinova, Alexandra S; Denève, Sophie

    2017-01-01

    Schizophrenia (SCZ) is a complex mental disorder that may result in some combination of hallucinations, delusions and disorganized thinking. Here SCZ patients and healthy controls (CTLs) report their level of confidence on a forced-choice task that manipulated the strength of sensory evidence and prior information. Neither group's responses can be explained by simple Bayesian inference. Rather, individual responses are best captured by a model with different degrees of circular inference. Circular inference refers to a corruption of sensory data by prior information and vice versa, leading us to ‘see what we expect' (through descending loops), to ‘expect what we see' (through ascending loops) or both. Ascending loops are stronger for SCZ than CTLs and correlate with the severity of positive symptoms. Descending loops correlate with the severity of negative symptoms. Both loops correlate with disorganized symptoms. The findings suggest that circular inference might mediate the clinical manifestations of SCZ. PMID:28139642

  19. Experimental evidence of pollination in marine flowers by invertebrate fauna

    PubMed Central

    van Tussenbroek, Brigitta I.; Villamil, Nora; Márquez-Guzmán, Judith; Wong, Ricardo; Monroy-Velázquez, L. Verónica; Solis-Weiss, Vivianne

    2016-01-01

    Pollen transport by water-flow (hydrophily) is a typical, and almost exclusive, adaptation of plants to life in the marine environment. It is thought that, unlike terrestrial environments, animals are not involved in pollination in the sea. The male flowers of the tropical marine angiosperm Thalassia testudinum open-up and release pollen in mucilage at night when invertebrate fauna is active. Here we present experimental evidence that, in the absence of water-flow, these invertebrates visit the flowers, carry and transfer mucilage mass with embedded pollen from the male flowers to the stigmas of the female flowers. Pollen tubes are formed on the stigmas, indicating that pollination is successful. Thus, T. testudinum has mixed abiotic–biotic pollination. We propose a zoobenthophilous pollination syndrome (pollen transfer in the benthic zone by invertebrate animals) which shares many characteristics with hydrophily, but flowers are expected to open-up during the night. PMID:27680661

  20. Experimental evidence of pollination in marine flowers by invertebrate fauna.

    PubMed

    van Tussenbroek, Brigitta I; Villamil, Nora; Márquez-Guzmán, Judith; Wong, Ricardo; Monroy-Velázquez, L Verónica; Solis-Weiss, Vivianne

    2016-09-29

    Pollen transport by water-flow (hydrophily) is a typical, and almost exclusive, adaptation of plants to life in the marine environment. It is thought that, unlike terrestrial environments, animals are not involved in pollination in the sea. The male flowers of the tropical marine angiosperm Thalassia testudinum open-up and release pollen in mucilage at night when invertebrate fauna is active. Here we present experimental evidence that, in the absence of water-flow, these invertebrates visit the flowers, carry and transfer mucilage mass with embedded pollen from the male flowers to the stigmas of the female flowers. Pollen tubes are formed on the stigmas, indicating that pollination is successful. Thus, T. testudinum has mixed abiotic-biotic pollination. We propose a zoobenthophilous pollination syndrome (pollen transfer in the benthic zone by invertebrate animals) which shares many characteristics with hydrophily, but flowers are expected to open-up during the night.

  1. Experimental evidence of condensation-driven airflow

    NASA Astrophysics Data System (ADS)

    Bunyard, P.; Hodnett, M.; Poveda, G.; Burgos Salcedo, J. D.; Peña, C.

    2015-10-01

    The dominant "convection" model of atmospheric circulation is based on the premise that hot air expands and rises, to be replaced by colder air, thereby creating horizontal surface winds. A recent theory put forward by Makarieva and Gorshkov (2007, 2013) maintains that the primary motive force of atmospheric circulation derives from the intense condensation and sharp pressure reduction that is associated with regions where a high rate of evapotranspiration from natural closed-canopy forests provides the "fuel" for cloud formation. The net result of the "biotic pump" theory is that moist air flows from ocean to land, drawn in by the pressure changes associated with a high rate of condensation. To test the physics underpinning the biotic pump theory, namely that condensation of water vapour, at a sufficiently high rate, results in an uni-directional airflow, a 5 m tall experimental apparatus was designed and built, in which a 20 m3 body of atmospheric air is enclosed inside an annular 14 m long space (a "square donut") around which it can circulate freely, allowing for rotary air flows. One vertical side of the apparatus contains some 17 m of copper refrigeration coils, which cause condensation. The apparatus contains a series of sensors measuring temperature, humidity and barometric pressure every five seconds, and air flow every second. The laws of Newtonian physics are used in calculating the rate of condensation inside the apparatus. The results of more than one hundred experiments show a highly significant correlation, with r2 > 0.9, of airflow and the rate of condensation. The rotary air flows created appear to be consistent both in direction and velocity with the biotic pump hypothesis, the critical factor being the rate change in the partial pressure of water vapour in the enclosed body of atmospheric air. Air density changes, in terms of kinetic energy, are found to be orders of magnitude smaller than the kinetic energy of partial pressure change. The

  2. Reconciling Experimental and Quasi-Experimental Evidence on the Impact of Full-Day Kindergarten

    ERIC Educational Resources Information Center

    Gibbs, Chloe

    2013-01-01

    This paper addresses the question of how to interpret evidence on the impact of full-day kindergarten resulting from different study designs, and provides guidance on how this evidence taken in tandem may inform the design and implementation of full-day kindergarten policies. Incorporating both experimental and quasi-experimental estimates on…

  3. Robustness and evidence of mechanisms in early experimental atherosclerosis research.

    PubMed

    Parkkinen, Veli-Pekka

    2016-12-01

    This article considers the evaluation of experimental evidence for a causal relation between cholesterol and atherosclerosis from the beginning of the 1900s until the late 1950s. It has been argued that the medical community failed to see the implications of this early research, and at first unjustifiably rejected a causal link between cholesterol and atherosclerosis. This article argues to the contrary that the medical community was justified to conclude based on the experimental evidence that cholesterol (dietary or blood) is probably not an effective target for preventive treatment. However, the evidence would have been sufficient to ascribe to cholesterol a contributing causal role in atherosclerotic heart disease. This view is argued for based on a rational reconstruction of the researchers' evaluation of evidence, specifically, the robustness of evidence for a manipulable dependence between cholesterol and atherosclerosis on the one hand, and the evidence for a mediating mechanism on the other. The case study is used to illustrate that robustness is a feasible methodological principle even when evidence is discordant, and evidence of mechanism should be evaluated on a par with evidence of statistical dependence in establishing causal claims. Copyright © 2016. Published by Elsevier Ltd.

  4. Experimental Study of Surface Dissolution Features on Kimberlite Indicator Minerals

    NASA Astrophysics Data System (ADS)

    McIsaac, E.; Fedortchouk, Y.

    2009-05-01

    During the ascent to the Earth's surface kimberlite magmas entrain mantle minerals - chromites, ilmenites, garnets and the most desirable - diamonds. Kimberlite magma partially dissolves these minerals during the ascent, producing different types of surface features on the minerals. Experiments showed that surface features on diamonds can be used to constrain composition of magmatic fluid. However, examining mantle minerals with more complex chemical compositions, such as chromites and ilmenites, could provide more detailed information about the composition and evolution of fluid system in the magmas, as determination of the depth of their entrainment is possible. This study experimentally investigates dissolution of chromites and ilmenites in melts with C-O-H fluid. The surface features produced at these conditions are then compared to the surface features on minerals recovered from kimberlites. The experiments were done in a piston-cylinder apparatus at 1350 - 1400°C and 1 GPa. Rounded natural mineral grains were placed in a synthetic mixture of Ca-Mg-Si-C-H-O composition with 0, 5, 13, 15, and 31 wt% H2O and 0, 5, and 27 wt% CO2. The experimental results investigated using Field-Emission Scanning Electron Microscope showed that angular step-like dissolution surfaces, which are common for natural kimberlitic chromites, develop only in the presence of H2O-rich fluid phase. The reaction of chromite with H2O dissolved in the melt and with dry melt caused smoothing of chromite surfaces. Chromite dissolution in CO2-rich melts produced rounded and polyhedral relief features. Both the smooth and polyhedral types of features are not typical for natural kimberlite-hosted chromite grains. Ilmenite underwent rapid dissolution at our experimental conditions. In H2O-rich fluid ilmenite produced "pyramidal" type of surface features previously described as the most common for natural kimberlitic ilmenites. The experimental results were compared to the natural minerals

  5. Experimental evidence for lattice effects in high temperature superconductors

    SciTech Connect

    Billinge, S.J.L.; Kwei, G.H.; Thompson, J.D.

    1994-01-18

    We present an overview of the experimental evidence for a role of the lattice in the mechanism of high temperature superconductivity. It appears unlikely that a solely conventional electron-phonon interaction produces the pairing. However, there is ample evidence of strong electron and spin to lattice coupling and observations of a response of the lattice to the electronic state. We draw attention to the importance of the local structure in discussions of lattice effects in high-{Tc} superconductivity.

  6. Microorganisms as Analytical Indicators. Experimental Methods and Techniques,

    DTIC Science & Technology

    1980-01-01

    analytic indicators: gram- negative and gram-positive sporiferous and nonsporiferous bacteria, yeasts, mycelial fungi, and actinomycetes (Refs. 4, 6-8...growing species of microorganisms, the cultivation period is appropriately increased. This factor is less important for actinomycetes , fungi and sporiferous

  7. Single-Subject Experimental Design for Evidence-Based Practice

    ERIC Educational Resources Information Center

    Byiers, Breanne J.; Reichle, Joe; Symons, Frank J.

    2012-01-01

    Purpose: Single-subject experimental designs (SSEDs) represent an important tool in the development and implementation of evidence-based practice in communication sciences and disorders. The purpose of this article is to review the strategies and tactics of SSEDs and their application in speech-language pathology research. Method: The authors…

  8. Single-Subject Experimental Design for Evidence-Based Practice

    ERIC Educational Resources Information Center

    Byiers, Breanne J.; Reichle, Joe; Symons, Frank J.

    2012-01-01

    Purpose: Single-subject experimental designs (SSEDs) represent an important tool in the development and implementation of evidence-based practice in communication sciences and disorders. The purpose of this article is to review the strategies and tactics of SSEDs and their application in speech-language pathology research. Method: The authors…

  9. Fecal microbiota transplantation: indications, methods, evidence, and future directions.

    PubMed

    Borody, Thomas J; Paramsothy, Sudarshan; Agrawal, Gaurav

    2013-08-01

    Fecal microbiota transplantation (FMT) has attracted great interest in recent years, largely due to the global Clostridium difficile infection (CDI) epidemic and major advances in metagenomic sequencing of the gastrointestinal (GI) microbiota, with growing understanding of its structure and function. FMT is now recommended as the most effective therapy for relapsing CDI and, with further refinement, may even be used in "first-time" CDI. There is interest also in other conditions related to GI dysbiosis--for example, inflammatory bowel disease, irritable bowel syndrome, obesity, and diabetes mellitus--although quality evidence is at present lacking. A few trials are now underway in FMT for ulcerative colitis. Many unanswered questions remain, including FMT methodology--for example, optimal route of administration, what makes a "good donor," safety issues, and long-term effects of FMT.

  10. Usability Evaluation and Implementation of a Health Information Technology Dashboard of Evidence-Based Quality Indicators.

    PubMed

    Schall, Mark Christopher; Cullen, Laura; Pennathur, Priyadarshini; Chen, Howard; Burrell, Keith; Matthews, Grace

    2017-06-01

    Health information technology dashboards that integrate evidence-based quality indicators can efficiently and accurately display patient risk information to promote early intervention and improve overall quality of patient care. We describe the process of developing, evaluating, and implementing a dashboard designed to promote quality care through display of evidence-based quality indicators within an electronic health record. Clinician feedback was sought throughout the process. Usability evaluations were provided by three nurse pairs and one physician from medical-surgical areas. Task completion times, error rates, and ratings of system usability were collected to compare the use of quality indicators displayed on the dashboard to the indicators displayed in a conventional electronic health record across eight experimental scenarios. Participants rated the dashboard as "highly usable" following System Usability Scale (mean, 87.5 [SD, 9.6]) and Poststudy System Usability Questionnaire (mean, 1.7 [SD, 0.5]) criteria. Use of the dashboard led to reduced task completion times and error rates in comparison to the conventional electronic health record for quality indicator-related tasks. Clinician responses to the dashboard display capabilities were positive, and a multifaceted implementation plan has been used. Results suggest application of the dashboard in the care environment may lead to improved patient care.

  11. Experimental evidence of contagious yawning in budgerigars (Melopsittacus undulatus).

    PubMed

    Gallup, Andrew C; Swartwood, Lexington; Militello, Janine; Sackett, Serena

    2015-09-01

    Experimental evidence of contagious yawning has only been documented in four mammalian species. Here, we report the results from two separate experimental studies designed to investigate the presence of contagious yawning in a social parrot, the budgerigar (Melopsittacus undulatus). In Study 1, birds were paired in adjacent cages with and without visual barriers, and the temporal association of yawning was assessed between visual conditions. In Study 2, the same birds were exposed to video stimuli of both conspecific yawns and control behavior, and yawning frequency was compared between conditions. Results from both studies demonstrate that yawning is contagious. To date, this is the first experimental evidence of contagious yawning in a non-mammalian species. We propose that future research could use budgerigars to explore questions related to basic forms of empathic processing.

  12. Further experimental evidence of the compressibility of arteries.

    PubMed

    Yossef, Ofry Efraim; Farajian, Mor; Gilad, Ilan; Willenz, Udi; Gutman, Nimrod; Yosibash, Zohar

    2017-01-01

    Further experimental evidence on the compressibility of arteries under normal physiological pressure range is provided using the experimental apparatus introduced in Yosibash et al., JMBBM 39(2014):339-354. We enlarged the experimental database by including almost twice the number of experiments, we considered a different artery - the porcine common carotid that allowed longer and larger diameters. In the physiological pressure range of 50-200mmHg, a relative volume change of 5% was obtained, lower compared to the sapheneous and femoral arteries (2-6%). Most of the arteries had a relative volume change of 1.5%. The relative volume change is found to be almost linearly proportional to the pressure, and inversely proportional to the dimensions of the experimented arteries (especially the artery length). The smaller the artery tested, the larger the relative volume change (such a phenomenon was also realized in Yosibash et al., JMBBM 39(2014):339-354.). We realized in recent past publications a flaw in the experimental protocol that results in an overestimation of the relative volume change (thus underestimating the bulk modulus). It is due to the consideration of experimental observations close to the zero pressure. Nontheless, in view of the experimental evidence, the pre-assumption of incompressibility in many phenomenological constitutive models of artery walls should be re-evaluated. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Experimental Evidence for Grazing System Research: What Does it Tell Us?

    USDA-ARS?s Scientific Manuscript database

    Research on grazing systems has been conducted for the past 60 years and the experimental evidence consistently indicates that rotational grazing is comparable to continuous grazing on rangelands. For example, over 80% of the peer-reviewed studies reported that rotational grazing did not result in h...

  14. Record dynamics: Direct experimental evidence from jammed colloids

    NASA Astrophysics Data System (ADS)

    Robe, Dominic M.; Boettcher, Stefan; Sibani, Paolo; Yunker, Peter

    2016-11-01

    In a broad class of complex materials a quench leads to a multi-scaled relaxation process known as aging. To explain its commonality and the astounding insensitivity to most microscopic details, record dynamics (RD) posits that a small set of increasingly rare and irreversible events, so-called quakes, controls the dynamics. While key predictions of RD are known to concur with a number of experimental and simulational results, its basic assumption on the nature of quake statistics has proven extremely difficult to verify experimentally. The careful distinction of rare (“record”) cage-breaking events from in-cage rattle accomplished in previous experiments on jammed colloids, enables us to extract the first direct experimental evidence for the fundamental hypothesis of RD that the rate of quakes decelerates with the inverse of the system age. The resulting description shows the predicted growth of the particle mean square displacement and of a mesoscopic lengthscale with the logarithm of time.

  15. Experimental evidence for mixed reality states in an interreality system.

    PubMed

    Gintautas, Vadas; Hübler, Alfred W

    2007-05-01

    We present experimental data on the limiting behavior of an interreality system comprising a virtual horizontally driven pendulum coupled to its real-world counterpart, where the interaction time scale is much shorter than the time scale of the dynamical system. We present experimental evidence that, if the physical parameters of the simplified virtual system match those of the real system within a certain tolerance, there is a transition from an uncorrelated dual reality state to a mixed reality state of the system in which the motion of the two pendula is highly correlated. The region in parameter space for stable solutions has an Arnold tongue structure for both the experimental data and a numerical simulation. As virtual systems better approximate real ones, even weak coupling in other interreality systems may produce sudden changes to mixed reality states.

  16. Chemicals and cancer in humans: first evidence in experimental animals.

    PubMed Central

    Huff, J

    1993-01-01

    Certain human diseases have been traced to exposure to environmental and occupational chemicals. In many instances the first evidence of potential adverse effects came from experimental studies and were subsequently discovered in humans. Associations of human cancers, as a diverse group of diseases, and chemicals have been made since the middle 1700s. Since then, nearly 100 chemicals, mixtures of chemicals, or exposure circumstances are now recognized as being or strongly implicated as being carcinogenic to humans. Of the less than 1000 agents evaluated adequately for carcinogenicity in laboratory animals, a varying spectrum of data from studies on humans are available for only about 20-25%. So far, more than 60 agents are linked unequivocally as causing cancer in humans, and another 50 or so are strongly suspected of being carcinogenic to humans. Not all of these have been or can be evaluated in animals because some are industrial processes or "occupations," some are environmental and cultural risk factors, and some are mixtures of agents. For those that can be studied experimentally, the qualitative concordance between humans and animals approaches unity, and in every case there is at least one common organ site of cancer in both species. The evidence of carcinogenicity in experimental animals preceded that observed in humans for nearly 30 agents and is the subject of this paper. PMID:8354167

  17. Experimental evidence for the exotic dibaryon d^{ast }1

    NASA Astrophysics Data System (ADS)

    Khrykin, A. S.

    2016-12-01

    We provide strong experimental evidence for the existence of a nonstrange exotic dibaryon with a mass of about 1956 MeV called d^{ast }1(1956). This dibaryon is expected to be stable against strong decay and decays predominantly into two nucleons ( NN) via the isospin-conserving radiative process d^{ast }1 to NN γ . First, we present the experimental evidence for the d^{ast }1(1956) found in the energy spectrum of the coincident photons emitted at ±900 from the reaction p p → p p γ γ at 216 MeV. Then we give an explanation why the WASA/CELSIUS Collaboration did not find signatures of this dibaryon in its proton-proton bremsstrahlung data measured at 310 and 200 MeV. We also present signatures of this dibaryon found in experimental invariant mass spectra of photon pairs from the p p → p p γ γ reaction measured by this collaboration at 1360 and 1200 MeV. These signatures provide very substantial confirmation of the existence of the d^{ast }1(1956).

  18. Fear creates an Allee effect: experimental evidence from seasonal populations.

    PubMed

    Elliott, Kyle H; Betini, Gustavo S; Norris, D Ryan

    2017-06-28

    Allee effects driven by predation can play a strong role in the decline of small populations but are conventionally thought to occur when generalist predators target specific prey (i.e. type II functional response). However, aside from direct consumption, fear of predators could also increase vigilance and reduce time spent foraging as population size decreases, as has been observed in wild mammals living in social groups. To investigate the role of fear on fitness in relation to population density in a species with limited sociality, we exposed varying densities of Drosophila melanogaster to mantid predators either during an experimental breeding season or non-breeding season. The presence of mantids in either season decreased the reproductive performance of individuals but only at low breeding densities, providing evidence for an Allee effect. We then used our experimental results to parametrize a mathematical model to examine the population consequences of fear at low densities. Fear tended to destabilize population dynamics and increase the risk of extinction up to sevenfold. Our study provides unique experimental evidence that the indirect effects of the presence of predators can cause an Allee effect and has important consequences for our understanding of the dynamics of small populations. © 2017 The Author(s).

  19. Single-Subject Experimental Design for Evidence-Based Practice

    PubMed Central

    Byiers, Breanne J.; Reichle, Joe; Symons, Frank J.

    2014-01-01

    Purpose Single-subject experimental designs (SSEDs) represent an important tool in the development and implementation of evidence-based practice in communication sciences and disorders. The purpose of this article is to review the strategies and tactics of SSEDs and their application in speech-language pathology research. Method The authors discuss the requirements of each design, followed by advantages and disadvantages. The logic and methods for evaluating effects in SSED are reviewed as well as contemporary issues regarding data analysis with SSED data sets. Examples of challenges in executing SSEDs are included. Specific exemplars of how SSEDs have been used in speech-language pathology research are provided throughout. Conclusion SSED studies provide a flexible alternative to traditional group designs in the development and identification of evidence-based practice in the field of communication sciences and disorders. PMID:23071200

  20. Experimental Evidence on Intermittent Lag Synchronization in Coupled Chua's Oscillators

    NASA Astrophysics Data System (ADS)

    Roy, P. K.; Dana, S. K.

    2003-08-01

    Phase synchronization (PS) in coupled chaotic oscillators has been investigated numerically in Lorenz, Rossler models and also experimentally in cardiorespiratory systems by many researchers. In non-identical oscillators, which is a reality, complete synchronization (CS) of amplitude and phase is difficult to arrive at. Lag synchronization (LS) is an intermediate step between complete (CS) and PS. PS shows promises in communication, in the context of pulse position modulation, in homoclinic chaotic systems. As has been observed earlier by others in numerical experiments that there is an intermittent region between PS and LS. This intermediate region is defined as the intermittent lag synchronization (ILS). Experimental evidence on both PS and ILS using two coupled Chua's oscillator (non-identical) is reported here.

  1. Experimental Evidence for Partonic Orbital Angular Momentum at RHIC

    SciTech Connect

    Fields, Douglas E.

    2011-12-14

    Although one might naively anticipate that the proton, being the lowest baryonic energy state, would be in a L = 0 state, the current theoretical understanding is that it must carry orbital angular momentum in order, for example, to have a non-zero anomalous magnetic moment. I will review the experimental evidence linked theoretically to orbital angular momentum of the proton's constituents from the RHIC experiments and summarize by presenting a challenge to the theory community--to develop a consistent framework which can explain the spin polarization asymmetries seen at RHIC and elsewhere, and give insight to the partonic wave-functions including orbital angular momentum.

  2. Experimental infections of the monogenean Gyrodactylus turnbulli indicate that it is not a strict specialist.

    PubMed

    King, T A; Cable, J

    2007-05-01

    Parasites represent a threat to endangered fish species, particularly when the parasite can host switch and the new host is vulnerable. If the parasite is highly host specific then successful host switching should be a rare occurrence; however, the host range of many parasites which are assumed to be specialists has never been tested. This includes the monogenean Gyrodactylus turnbulli, a well-studied ectoparasite found caudally on its known host, the guppy, Poecilia reticulata. In this study, we monitored parasite establishment and reproduction on a range of poeciliids and more distantly related fish. Individually maintained fish were experimentally infected with a single parasite and monitored daily to establish whether G. turnbulli could survive and reproduce on other fish species. Gyrodactylus turnbulli can infect a wider range of hosts than previously considered, highlighting the fact that host specificity can never be assumed unless experimentally tested. Our findings also have significant implications for parasite transmission to novel hosts and provide further insight into the evolutionary origins of this ubiquitous group of fish pathogens. Previous molecular evidence indicates that host switching is the key mechanism for speciation within the genus Gyrodactylus. Until recently, most Gyrodactylus spp. were assumed to be narrowly host specific. However, our findings suggest that even so-called specialist species, such as G. turnbulli, may represent a threat to vulnerable fish stocks. In view of the potential importance of host switching under artificial conditions, we propose to describe this as 'artificial ecological transfer' as opposed to 'natural ecological transfer', host switching under natural conditions.

  3. Experimental evidence for compositional syntax in bird calls.

    PubMed

    Suzuki, Toshitaka N; Wheatcroft, David; Griesser, Michael

    2016-03-08

    Human language can express limitless meanings from a finite set of words based on combinatorial rules (i.e., compositional syntax). Although animal vocalizations may be comprised of different basic elements (notes), it remains unknown whether compositional syntax has also evolved in animals. Here we report the first experimental evidence for compositional syntax in a wild animal species, the Japanese great tit (Parus minor). Tits have over ten different notes in their vocal repertoire and use them either solely or in combination with other notes. Experiments reveal that receivers extract different meanings from 'ABC' (scan for danger) and 'D' notes (approach the caller), and a compound meaning from 'ABC-D' combinations. However, receivers rarely scan and approach when note ordering is artificially reversed ('D-ABC'). Thus, compositional syntax is not unique to human language but may have evolved independently in animals as one of the basic mechanisms of information transmission.

  4. Experimental evidence for compositional syntax in bird calls

    PubMed Central

    Suzuki, Toshitaka N.; Wheatcroft, David; Griesser, Michael

    2016-01-01

    Human language can express limitless meanings from a finite set of words based on combinatorial rules (i.e., compositional syntax). Although animal vocalizations may be comprised of different basic elements (notes), it remains unknown whether compositional syntax has also evolved in animals. Here we report the first experimental evidence for compositional syntax in a wild animal species, the Japanese great tit (Parus minor). Tits have over ten different notes in their vocal repertoire and use them either solely or in combination with other notes. Experiments reveal that receivers extract different meanings from ‘ABC' (scan for danger) and ‘D' notes (approach the caller), and a compound meaning from ‘ABC–D' combinations. However, receivers rarely scan and approach when note ordering is artificially reversed (‘D–ABC'). Thus, compositional syntax is not unique to human language but may have evolved independently in animals as one of the basic mechanisms of information transmission. PMID:26954097

  5. Experimental evidence for a two-dimensional quantized Hall insulator

    NASA Astrophysics Data System (ADS)

    Hilke, M.; Shahar, D.; Song, S. H.; Tsui, D. C.; Xie, Y. H.; Monroe, Don

    1998-10-01

    The general theoretical definition of an insulator is a material in which the conductivity vanishes at the absolute zero of temperature. In classical insulators, such as materials with a band gap, vanishing conductivities lead to diverging resistivities. But other insulators can show more complex behaviour, particularly in the presence of a high magnetic field, where different components of the resistivity tensor can display different behaviours: the magnetoresistance diverges as the temperature approaches absolute zero, but the transverse (Hall) resistance remains finite. Such a system is known as a Hall insulator. Here we report experimental evidence for a quantized Hall insulator in a two-dimensional electron system-confined in a semiconductor quantum well. The Hall resistance is quantized in the quantum unit of resistance h/e2, where h is Planck's constant and e the electronic charge. At low fields, the sample reverts to being a normal Hall insulator.

  6. Experimental evidence that sperm maturation drives protandry in an ectotherm.

    PubMed

    Breedveld, Merel C; Fitze, Patrick S

    2016-09-01

    Protandry, i.e., the earlier arrival to breeding areas of males than females, has attracted a lot of scientific attention. However, evidence for the evolutionary hypotheses of protandry is surprisingly scarce. Here, we experimentally manipulate the time of emergence from hibernation of males, relative to females, in the common lizard, Zootoca vivipara. We test whether the timing of emergence affects sperm maturation and mating success, to disentangle among proposed selective advantages of protandry. Our results experimentally demonstrate that the timing of emergence affects the date of sperm presence. Moreover, the degree of protandry affected whether males had sperm upon their first encounter with females, but it did not affect the probability of copulating. Mating occurred independent of male fertility and mating during infertility was least common in early emerging males. Early emergence from hibernation by males, relative to females, thus increases the male's chance of fertilising eggs and later emergence from hibernation by females reduces the female's probability of mating with infertile males. These results point to direct reproductive benefits of protandry in males and females, where earlier emergence is predicted to increase the male's opportunities to inseminate mates, and later emergence reduces the female's probability of copulating with infertile males. This suggests that protandry evolved due to the time required for sperm maturation after emergence from hibernation.

  7. Experimental evidence for action imitation in killer whales (Orcinus orca).

    PubMed

    Abramson, José Z; Hernández-Lloreda, Victoria; Call, Josep; Colmenares, Fernando

    2013-01-01

    Comparative experimental studies of imitative learning have focused mainly on primates and birds. However, cetaceans are promising candidates to display imitative learning as they have evolved in socioecological settings that have selected for large brains, complex sociality, and coordinated predatory tactics. Here we tested imitative learning in killer whales, Orcinus orca. We used a 'do-as-other-does' paradigm in which 3 subjects witnessed a conspecific demonstrator's performance that included 15 familiar and 4 novel behaviours. The three subjects (1) learned the copy command signal 'Do that' very quickly, that is, 20 trials on average; (2) copied 100 % of the demonstrator's familiar and novel actions; (3) achieved full matches in the first attempt for 8-13 familiar behaviours (out of 15) and for the 2 novel behaviours (out of 2) in one subject; and (4) took no longer than 8 trials to accurately copy any familiar behaviour, and no longer than 16 trials to copy any novel behaviour. This study provides experimental evidence for body imitation, including production imitation, in killer whales that is comparable to that observed in dolphins tested under similar conditions. These findings suggest that imitative learning may underpin some of the group-specific traditions reported in killer whales in the field.

  8. Experimental evidence that parasites drive eco-evolutionary feedbacks.

    PubMed

    Brunner, Franziska S; Anaya-Rojas, Jaime M; Matthews, Blake; Eizaguirre, Christophe

    2017-04-04

    Host resistance to parasites is a rapidly evolving trait that can influence how hosts modify ecosystems. Eco-evolutionary feedbacks may develop if the ecosystem effects of host resistance influence selection on subsequent host generations. In a mesocosm experiment, using a recently diverged (<100 generations) pair of lake and stream three-spined sticklebacks, we tested how experimental exposure to a common fish parasite (Gyrodactylus spp.) affects interactions between hosts and their ecosystems in two environmental conditions (low and high nutrients). In both environments, we found that stream sticklebacks were more resistant to Gyrodactylus and had different gene expression profiles than lake sticklebacks. This differential infection led to contrasting effects of sticklebacks on a broad range of ecosystem properties, including zooplankton community structure and nutrient cycling. These ecosystem modifications affected the survival, body condition, and gene expression profiles of a subsequent fish generation. In particular, lake juvenile fish suffered increased mortality in ecosystems previously modified by lake adults, whereas stream fish showed decreased body condition in stream fish-modified ecosystems. Parasites reinforced selection against lake juveniles in lake fish-modified ecosystems, but only under oligotrophic conditions. Overall, our results highlight the overlapping timescales and the interplay of host-parasite and host-ecosystem interactions. We provide experimental evidence that parasites influence host-mediated effects on ecosystems and, thereby, change the likelihood and strength of eco-evolutionary feedbacks.

  9. Experimental evidence for deterministic chaos in thermal pulse combustion

    SciTech Connect

    Daw, C.S.; Thomas, J.F.; Richards, G.A.; Narayanaswami, L.L.

    1994-12-31

    Given the existence of chaotic oscillations in reacting chemical systems, it is reasonable to ask whether or not similar phenomena can occur in combustion. In this paper, the authors present experimental evidence that kinetically driven chaos occurs in a highly simplified thermal pulse combustor. The combustor is a well-stirred reactor with a tailpipe extending from one end. Fuel and air are injected into the combustion chamber through orifices in the end opposite the tailpipe. Propane with the fuel used in all cases. From the experimental data analyses, it is clear that deterministic chaos is an important factor in thermal pulse combustor dynamics. While the authors have only observed such behavior in this particular type combustor to date, they infer from their understanding of the origins of the chaos that it is likely to exist in other pulse combustors and even nonpulsing combustion. They speculate that realization of the importance of chaos in affecting flame stability could lead to significant changes in combustor design and control.

  10. Evaluating experimental cerebral malaria using oxidative stress indicator OKD48 mice.

    PubMed

    Imai, Takashi; Iwawaki, Takao; Akai, Ryoko; Suzue, Kazutomo; Hirai, Makoto; Taniguchi, Tomoyo; Okada, Hiroko; Hisaeda, Hajime

    2014-09-01

    Cerebral malaria is a fatal complication of malaria. Conventional methods for evaluating experimental cerebral malaria have several drawbacks. Therefore, we aimed to develop an easy-to-use method for evaluating experimental cerebral malaria using OKD48 (Keap1-dependent Oxidative stress Detector, No-48-luciferase) mice to evaluate oxidative stress. OKD48 mice infected with Plasmodium berghei ANKA strain (PbA) suffered from experimental cerebral malaria and oxidative stress was successfully detected in the brains of living OKD48 mice developing experimental cerebral malaria. Oxidative stress in the brain was dependent on the development of experimental cerebral malaria, as prevention of experimental cerebral malaria did not elicit oxidative stress. We provide a novel evaluation method for experimental cerebral malaria using oxidative stress indicator OKD48 mice. Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

  11. Experimental and modelling evidence of shortening heat in cardiac muscle.

    PubMed

    Tran, Kenneth; Han, June-Chiew; Crampin, Edmund John; Taberner, Andrew James; Loiselle, Denis Scott

    2017-10-01

    Heat associated with muscle shortening has been repeatedly demonstrated in skeletal muscle, but its existence in cardiac muscle remains contentious after five decades of study. By iterating between experiments and computational modelling, we show compelling evidence for the existence of shortening heat in cardiac muscle and reveal, mechanistically, the source of this excess heat. Our results clarify a long-standing uncertainty in the field of cardiac muscle energetics. We provide a revised partitioning of cardiac muscle energy expenditure to include this newly revealed thermal component. When a muscle shortens against an afterload, the heat that it liberates is greater than that produced by the same muscle contracting isometrically at the same level of force. This excess heat is defined as 'shortening heat', and has been repeatedly demonstrated in skeletal muscle but not in cardiac muscle. Given the micro-structural similarities between these two muscle types, and since we imagine that shortening heat is the thermal accompaniment of cross-bridge cycling, we have re-examined this issue. Using our flow-through microcalorimeter, we measured force and heat generated by isolated rat trabeculae undergoing isometric contractions at different muscle lengths and work-loop (shortening) contractions at different afterloads. We simulated these experimental protocols using a thermodynamically constrained model of cross-bridge cycling and probed the mechanisms underpinning shortening heat. Predictions generated by the model were subsequently validated by a further set of experiments. Both our experimental and modelling results show convincing evidence for the existence of shortening heat in cardiac muscle. Its magnitude is inversely related to the afterload or, equivalently, directly related to the extent of shortening. Computational simulations reveal that the heat of shortening arises from the cycling of cross-bridges, and that the rate of ATP hydrolysis is more sensitive to

  12. The mechanics of intermediate and deep focus earthquakes: experimental evidences

    NASA Astrophysics Data System (ADS)

    Schubnel, A.; Hilairet, N.; Ferrand, T. P.; Incel, S.; Labrousse, L.; Renner, J.; Gasc, J.; Wang, Y.; Green, H. W., II

    2015-12-01

    At least part of the subducting slab seismic activity could be triggered by phase transformations and mineral reactions. However, the way mineral reactions can modify the deformation regime of deep rocks, from ductile to brittle (embrittlement) is still poorly understood and remains one of the outstanding unsolved problems of geophysics and rock mechanics. Here, we provide experimental evidence that, under differential stress at high pressure and temperature conditions (3-5GPa/800-1000°C), shear fractures nucleate and propagate at the onset of the olivine -> spinel transition in the Mg2GeO4 analogue system. The propagation of these fractures is sufficiently rapid to radiate energy in the form of intense acoustic emissions (AEs). Using a similar set-up, a second set of experiments demonstrates that glaucophane and lawsonite mixtures, two of the principal mineral water carriers in the subducted oceanic crust, undergo dynamic fracture instabilities when deformed within the eclogite field (3GPa/400-800°C). This time, AEs are observed due respectively to the glaucophane breakdown into jadeite and talc under low temperature and lawsonite dehydration under higher temperature. Finally, deformation experiments performed on partially serpentinized peridotites at 2-4GPa, 500-700°C, demonstrate that 5% serpentine in sufficient to trigger dehydration embrittlement of the peridotite body. In this case, low serpentine contents may favor initiation of mechanical failure of the olivine "load bearing" network. In all these three cases, various post-mortem microstructural observations techniques (SEM, TEM, Raman, Microprobe, X-ray tomography) reveals that samples deformed under stress almost systematically present high presure (HP) faulting, to the contrary of samples transformed under isostatic conditions. In addition, AEs correspond to acoustic waves radiated by dynamic HP transformational faulting and follow the Gutenberg-Richter law over sometimes more than 4 orders of moment

  13. Experimental evidence for two different dynamical regimes in liquid rubidium

    NASA Astrophysics Data System (ADS)

    Demmel, Franz; Morkel, Christoph

    2017-08-01

    We present evidence for changes in the dynamics of liquid rubidium with rising temperature. The thermal expansion of this liquid alkali metal shows a changing derivative with temperature in a temperature range of about 400-500 K. With neutron scattering the amplitude at the structure factor maximum demonstrates a changing slope with increasing temperature. A derived averaged structural relaxation time can be understood that an additional relaxation process sets in upon cooling. The deduced generalized viscosity and high frequency shear modulus indicate a change in dynamics in the same temperature range. All these findings point to a change in dynamics of the equilibrium liquid metal state with a dynamical crossover from a viscous to a fluid-like liquid metal well above the melting point.

  14. Insulin Resistance and Environmental Pollutants: Experimental Evidence and Future Perspectives

    PubMed Central

    Vanparys, Caroline; Van Gaal, Luc F.; Jorens, Philippe G.; Covaci, Adrian; Blust, Ronny

    2013-01-01

    Background: The metabolic disruptor hypothesis postulates that environmental pollutants may be risk factors for metabolic diseases. Because insulin resistance is involved in most metabolic diseases and current health care prevention programs predominantly target insulin resistance or risk factors thereof, a critical analysis of the role of pollutants in insulin resistance might be important for future management of metabolic diseases. Objectives: We aimed to critically review the available information linking pollutant exposure to insulin resistance and to open the discussion on future perspectives for metabolic disruptor identification and prioritization strategies. Methods: We searched PubMed and Web of Science for experimental studies reporting on linkages between environmental pollutants and insulin resistance and identified a total of 23 studies as the prime literature. Discussion: Recent studies specifically designed to investigate the effect of pollutants on insulin sensitivity show a potential causation of insulin resistance. Based on these studies, a summary of viable test systems and end points can be composed, allowing insight into what is missing and what is needed to create a standardized insulin resistance toxicity testing strategy. Conclusions: It is clear that current research predominantly relies on top-down identification of insulin resistance–inducing metabolic disruptors and that the development of dedicated in vitro or ex vivo screens to allow animal sparing and time- and cost-effective bottom-up screening is a major future research need. Citation: Hectors TL, Vanparys C, Van Gaal LF, Jorens PG, Covaci A, Blust R. 2013. Insulin resistance and environmental pollutants: experimental evidence and future perspectives. Environ Health Perspect 121:1273–1281; http://dx.doi.org/10.1289/ehp.1307082 PMID:24058052

  15. Experimental evidence of hepatitis A virus infection in pigs.

    PubMed

    Song, Young-Jo; Park, Woo-Jung; Park, Byung-Joo; Kwak, Sang-Woo; Kim, Yong-Hyeon; Lee, Joong-Bok; Park, Seung-Yong; Song, Chang-Seon; Lee, Sang-Won; Seo, Kun-Ho; Kang, Young-Sun; Park, Choi-Kyu; Song, Jae-Young; Choi, In-Soo

    2016-04-01

    Hepatitis A virus (HAV) is the leading cause of acute viral hepatitis worldwide, with HAV infection being restricted to humans and nonhuman primates. In this study, HAV infection status was serologically determined in domestic pigs and experimental infections of HAV were attempted to verify HAV infectivity in pigs. Antibodies specific to HAV or HAV-like agents were detected in 3.5% of serum samples collected from pigs in swine farms. When the pigs were infected intravenously with 2 × 10(5) 50% tissue culture infectious dose (TCID50 ) of HAV, shedding of the virus in feces, viremia, and seroconversion were detected. In pigs orally infected with the same quantity of HAV, viral shedding was detected only in feces. HAV genomic RNA was detected in the liver and bile of intravenously infected pigs, but only in the bile of orally infected pigs. In further experiments, pigs were intravenously infected with 6 × 10(5) TCID50 of HAV. Shedding of HAV in feces, along with viremia and seroconversion, were confirmed in infected pigs but not in sentinel pigs. HAV genomic RNA was detected in the liver, bile, spleen, lymph node, and kidney of the infected pigs. HAV antigenomic RNA was detected in the spleen of one HAV-infected pig, suggesting HAV replication in splenic cells. Infiltration of inflammatory cells was observed in the livers of infected pigs but not in controls. This is the first experimental evidence to demonstrate that human HAV strains can infect pigs. © 2015 Wiley Periodicals, Inc.

  16. Semantics guide infants' vowel learning: Computational and experimental evidence.

    PubMed

    Ter Schure, S M M; Junge, C M M; Boersma, P P G

    2016-05-01

    In their first year, infants' perceptual abilities zoom in on only those speech sound contrasts that are relevant for their language. Infants' lexicons do not yet contain sufficient minimal pairs to explain this phonetic categorization process. Therefore, researchers suggested a bottom-up learning mechanism: infants create categories aligned with the frequency distributions of sounds in their input. Recent evidence shows that this bottom-up mechanism may be complemented by the semantic context in which speech sounds occur, such as simultaneously present objects. To test this hypothesis, we investigated whether discrimination of a non-native vowel contrast improves when sounds from the contrast were paired consistently or randomly with two distinct visually presented objects, while the distribution of speech tokens suggested a single broad category. This was assessed in two ways: computationally, namely in a neural network simulation, and experimentally, namely in a group of 8-month-old infants. The neural network, trained with a large set of sound-meaning pairs, revealed that two categories emerge only if sounds are consistently paired with objects. A group of 49 real 8-month-old infants did not immediately show sensitivity to the pairing condition; a later test at 18 months with some of the same infants, however, showed that this sensitivity at 8 months interacted with their vocabulary size at 18 months. This interaction can be explained by the idea that infants with larger future vocabularies are more positively influenced by consistent training (and/or more negatively influenced by inconsistent training) than infants with smaller future vocabularies. This suggests that consistent pairing with distinct visual objects can help infants to discriminate speech sounds even when the auditory information does not signal a distinction. Together our results give computational as well as experimental support for the idea that semantic context plays a role in disambiguating

  17. Experimental Evidence for Phonemic Contrasts in a Nonhuman Vocal System.

    PubMed

    Engesser, Sabrina; Crane, Jodie M S; Savage, James L; Russell, Andrew F; Townsend, Simon W

    2015-06-01

    The ability to generate new meaning by rearranging combinations of meaningless sounds is a fundamental component of language. Although animal vocalizations often comprise combinations of meaningless acoustic elements, evidence that rearranging such combinations generates functionally distinct meaning is lacking. Here, we provide evidence for this basic ability in calls of the chestnut-crowned babbler (Pomatostomus ruficeps), a highly cooperative bird of the Australian arid zone. Using acoustic analyses, natural observations, and a series of controlled playback experiments, we demonstrate that this species uses the same acoustic elements (A and B) in different arrangements (AB or BAB) to create two functionally distinct vocalizations. Specifically, the addition or omission of a contextually meaningless acoustic element at a single position generates a phoneme-like contrast that is sufficient to distinguish the meaning between the two calls. Our results indicate that the capacity to rearrange meaningless sounds in order to create new signals occurs outside of humans. We suggest that phonemic contrasts represent a rudimentary form of phoneme structure and a potential early step towards the generative phonemic system of human language.

  18. Experimental evidence for the thermophilicity of ancestral life.

    PubMed

    Akanuma, Satoshi; Nakajima, Yoshiki; Yokobori, Shin-ichi; Kimura, Mitsuo; Nemoto, Naoki; Mase, Tomoko; Miyazono, Ken-ichi; Tanokura, Masaru; Yamagishi, Akihiko

    2013-07-02

    Theoretical studies have focused on the environmental temperature of the universal common ancestor of life with conflicting conclusions. Here we provide experimental support for the existence of a thermophilic universal common ancestor. We present the thermal stabilities and catalytic efficiencies of nucleoside diphosphate kinases (NDK), designed using the information contained in predictive phylogenetic trees, that seem to represent the last common ancestors of Archaea and of Bacteria. These enzymes display extreme thermal stabilities, suggesting thermophilic ancestries for Archaea and Bacteria. The results are robust to the uncertainties associated with the sequence predictions and to the tree topologies used to infer the ancestral sequences. Moreover, mutagenesis experiments suggest that the universal ancestor also possessed a very thermostable NDK. Because, as we show, the stability of an NDK is directly related to the environmental temperature of its host organism, our results indicate that the last common ancestor of extant life was a thermophile that flourished at a very high temperature.

  19. A preliminary study of wildland fire pattern indicator reliability following an experimental fire

    Treesearch

    Albert Simeoni; Zachary C. Owens; Erik W. Christiansen; Abid Kemal; Michael Gallagher; Kenneth L. Clark; Nicholas Skowronski; Eric V. Mueller; Jan C. Thomas; Simon Santamaria; Rory M. Hadden

    2017-01-01

    An experimental fire was conducted in 2016, in the Pinelands National Reserve of New Jersey, to assess the reliability of the fire pattern indicators used in wildland fire investigation. Objects were planted in the burn area to support the creation of the indicators. Fuel properties and environmental data were recorded. Video and infrared cameras were used to document...

  20. Experimental evidence for carbonate stability in the Earth's lower mantle

    NASA Astrophysics Data System (ADS)

    Biellmann, Claudine; Gillet, Philippe; Guyot, Francois; Peyronneau, Jean; Reynard, Bruno

    1993-07-01

    We present experimental results on the stability of carbonates up to 50 GPa and at high temperatures (1500-2500 K). The experiments were conducted in a laser-heated diamond anvil cell, and the run products were characterized by analytical TEM. Dolomite is shown to break down to a CaCO3 + MgCO3 assemblage at pressures between 20 and 50 GPa. No decarbonation was evident, suggesting that carbonates remain stable under these conditions with respect to rocksalt oxide + CO2 assemblages. Equimolar mixed powders of dolomite + enstatite and dolomite + olivine were transformed into magnesite + calcic perovskite and into magnesite + calcic and magnesian perovskites + magnesiowustite, respectively. The very strong partitioning of Ca in silicates suggests that magnesite is the stable carbonate in the presence of silicates in the Earth's lower mantle down to at least 1500 km. Finally, eutectoid or eutectic intergrowth of magnesiowustite and magnesite is observed, suggesting a possible mutual solubility between these two phases at high pressures and high temperatures. Lower mantle magnesiowustite may provide an alternative host for carbon in the Earth's lower mantle.

  1. Yield strength of microcrystalline cellulose: experimental evidence by dielectric spectroscopy.

    PubMed

    Khomane, Kailas S; Bansal, Arvind K

    2013-10-15

    The water-induced ionic charge transport in compacted microcrystalline cellulose (MCC) has been reported to be governed by the densification behaviour. Hence, mechanical properties were expected to correlate with conductivity behaviour of MCC compacts. Both in-die and out-of-die compaction behaviour of MCC powder was investigated using a fully instrumented rotary tablet press. The dielectric measurements were carried out using a Novocontrol Concept 40 broadband dielectric spectrometer and dc conductivity (σdc) was extracted from the low frequency conductivity data at room temperature. As postulated, compaction pressure corresponding to maximum conductivity (σdc max) was observed to correlate with yield strength of MCC, determined using in-die and out-of-die Heckel analysis. Although Heckel transformation is most commonly used in pharmaceutical technology, its general use to characterise the mechanical properties of organic pharmaceutical materials has been criticized. The present study has provided experimental evidence that Heckel equation is practically useful to describe plastic deformation of organic pharmaceutical powders.

  2. An Evaluation of Multiple Single-Case Outcome Indicators Using Convergent Evidence Scaling

    ERIC Educational Resources Information Center

    McGill, Ryan J.; Busse, R. T.

    2014-01-01

    The purpose of this article is to evaluate the consistency of five single-case outcome indicators, used to assess response-to-intervention data from a pilot Tier 2 reading intervention that was implemented at an elementary school. Using convergent evidence scaling, the indicators were converted onto a common interpretive scale for each case…

  3. An Evaluation of Multiple Single-Case Outcome Indicators Using Convergent Evidence Scaling

    ERIC Educational Resources Information Center

    McGill, Ryan J.; Busse, R. T.

    2014-01-01

    The purpose of this article is to evaluate the consistency of five single-case outcome indicators, used to assess response-to-intervention data from a pilot Tier 2 reading intervention that was implemented at an elementary school. Using convergent evidence scaling, the indicators were converted onto a common interpretive scale for each case…

  4. Early-Life Nutritional Programming of Type 2 Diabetes: Experimental and Quasi-Experimental Evidence

    PubMed Central

    Vaiserman, Alexander M.

    2017-01-01

    Consistent evidence from both experimental and human studies suggest that inadequate nutrition in early life can contribute to risk of developing metabolic disorders including type 2 diabetes (T2D) in adult life. In human populations, most findings supporting a causative relationship between early-life malnutrition and subsequent risk of T2D were obtained from quasi-experimental studies (‘natural experiments’). Prenatal and/or early postnatal exposures to famine were demonstrated to be associated with higher risk of T2D in many cohorts around the world. Recent studies have highlighted the importance of epigenetic regulation of gene expression as a possible major contributor to the link between the early-life famine exposure and T2D in adulthood. Findings from these studies suggest that prenatal exposure to the famine may result in induction of persistent epigenetic changes that have adaptive significance in postnatal development but can predispose to metabolic disorders including T2D at the late stages of life. In this review, quasi-experimental data on the developmental programming of T2D are summarized and recent research findings on changes in DNA methylation that mediate these effects are discussed. PMID:28273874

  5. Predicting the Unpredictable: 75 Years of Experimental Evidence

    NASA Astrophysics Data System (ADS)

    Radin, Dean I.

    2011-11-01

    From time immemorial, people have reported foreknowledge of future events. To determine whether such experiences are best understood via conventional explanations, or whether a retrocausal phenomenon might be involved in some instances, researchers have conducted hundreds of controlled laboratory experiments over the past 75 years. These studies fall into four general classes, and each class has generated repeatable evidence consistent with retrocausation. The statistical results for a class of forced-choice studies is associated with odds against chance of about 1024; for a class of free-response studies, odds about 1020; for psychophysiological-based studies, odds about 1017; and for implicit decision studies, odds about 1010. Effect sizes observed in the latter three classes are nearly identical, indicating replication of similar underlying effects. These effects are also in close agreement with the average effect size across 25,000 conventional social psychology experiments conducted over the last century, suggesting that retrocausal phenomena may not be especially unique, at least not in terms of the magnitude of effect. Bayesian analyses of the most recent classes of experiments confirm that the evidence is strongly in favor of a genuine effect, with Bayes Factors ranging from 13,669 to 1 for implicit decision experiments, to 2.9×1013 to 1 for psychophysiological designs. For the two most recent classes of studies examining retrocausal effects via unconscious physiological or behavioral measures, 85 of 101 studies (84%) reported by 25 different laboratories from the United States, Italy, Spain, Holland, Austria, Sweden, England, Scotland, Iran, Japan, and Australia, have produced results in the direction predicted by a retrocausal effect (odds against chance = 1.3×1012, via a sign test). Assessment of the methodologies used in these studies has not identified plausible conventional alternatives for the observed outcomes, suggesting the existence of a

  6. Experimental evidence of bark beetle adaptation to a fungal symbiont.

    PubMed

    Bracewell, Ryan R; Six, Diana L

    2015-11-01

    The importance of symbiotic microbes to insects cannot be overstated; however, we have a poor understanding of the evolutionary processes that shape most insect-microbe interactions. Many bark beetle (Coleoptera: Curculionidae, Scolytinae) species are involved in what have been described as obligate mutualisms with symbiotic fungi. Beetles benefit through supplementing their nutrient-poor diet with fungi and the fungi benefit through gaining transportation to resources. However, only a few beetle-fungal symbioses have been experimentally manipulated to test whether the relationship is obligate. Furthermore, none have tested for adaptation of beetles to their specific symbionts, one of the requirements for coevolution. We experimentally manipulated the western pine beetle-fungus symbiosis to determine whether the beetle is obligately dependent upon fungi and to test for fine-scale adaptation of the beetle to one of its symbiotic fungi, Entomocorticium sp. B. We reared beetles from a single population with either a natal isolate of E. sp. B (isolated from the same population from which the beetles originated), a non-natal isolate (a genetically divergent isolate from a geographically distant beetle population), or with no fungi. We found that fungi were crucial for the successful development of western pine beetles. We also found no significant difference in the effects of the natal and non-natal isolate on beetle fitness parameters. However, brood adult beetles failed to incorporate the non-natal fungus into their fungal transport structure (mycangium) indicating adaption by the beetle to particular genotypes of symbiotic fungi. Our results suggest that beetle-fungus mutualisms and symbiont fidelity may be maintained via an undescribed recognition mechanism of the beetles for particular symbionts that may promote particular associations through time.

  7. Self-Organization of Blood Pressure Regulation: Experimental Evidence

    PubMed Central

    Fortrat, Jacques-Olivier; Levrard, Thibaud; Courcinous, Sandrine; Victor, Jacques

    2016-01-01

    Blood pressure regulation is a prime example of homeostatic regulation. However, some characteristics of the cardiovascular system better match a non-linear self-organized system than a homeostatic one. To determine whether blood pressure regulation is self-organized, we repeated the seminal demonstration of self-organized control of movement, but applied it to the cardiovascular system. We looked for two distinctive features peculiar to self-organization: non-equilibrium phase transitions and hysteresis in their occurrence when the system is challenged. We challenged the cardiovascular system by means of slow, 20-min Tilt-Up and Tilt-Down tilt table tests in random order. We continuously determined the phase between oscillations at the breathing frequency of Total Peripheral Resistances and Heart Rate Variability by means of cross-spectral analysis. We looked for a significant phase drift during these procedures, which signed a non-equilibrium phase transition. We determined at which head-up tilt angle it occurred. We checked that this angle was significantly different between Tilt-Up and Tilt-Down to demonstrate hysteresis. We observed a significant non-equilibrium phase transition in nine healthy volunteers out of 11 with significant hysteresis (48.1 ± 7.5° and 21.8 ± 3.9° during Tilt-Up and Tilt-Down, respectively, p < 0.05). Our study shows experimental evidence of self-organized short-term blood pressure regulation. It provides new insights into blood pressure regulation and its related disorders. PMID:27065880

  8. Experimental evidence for sexual selection against inbred males.

    PubMed

    Vega-Trejo, Regina; Head, Megan L; Keogh, J Scott; Jennions, Michael D

    2017-03-01

    The detrimental effects of matings between relatives are well known. However, few studies determine the extent to which inbreeding depression in males is due to natural or sexual selection. Importantly, measuring fitness or key fitness components, rather than phenotypic traits allows more accurate estimation of inbreeding depression. We investigate how differences in inbreeding and juvenile diet (i.e. early stressful environment) influence a key component of male fitness, namely their reproductive success. We experimentally created inbred and outbred male mosquitofish (Gambusia holbrooki) by mating full-sibs (f = 0·25). We show that this led to a 23% reduction in genome-wide heterozygosity based on SNPs. Males were raised on different diets early in life to create high-stress and low-stress rearing environments. We then allowed adult males to compete freely for females to test if inbreeding, early diet and their interaction affect a male's share of paternity. Early diet had no effect on paternity, but outbred males sired almost twice as many offspring as inbred males (n = 628 offspring from 122 potential sires). Using artificial insemination methods we determined that this was unlikely to be due to early embryo mortality of eggs fertilised by inbred males: there was no evidence that male inbreeding status affects the realised fecundity of females (n = 288). Given there was no difference in male mortality in our competitive mating experiment, the lower reproductive success of inbred males can most parsimoniously be attributed to inbreeding negatively affecting sexually selected traits that affect male mating success and/or sperm competitiveness. We discuss which sexually selected traits might be involved. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

  9. Experimental evidence that wildflower strips increase pollinator visits to crops

    PubMed Central

    Feltham, Hannah; Park, Kirsty; Minderman, Jeroen; Goulson, Dave

    2015-01-01

    Wild bees provide a free and potentially diverse ecosystem service to farmers growing pollination-dependent crops. While many crops benefit from insect pollination, soft fruit crops, including strawberries are highly dependent on this ecosystem service to produce viable fruit. However, as a result of intensive farming practices and declining pollinator populations, farmers are increasingly turning to commercially reared bees to ensure that crops are adequately pollinated throughout the season. Wildflower strips are a commonly used measure aimed at the conservation of wild pollinators. It has been suggested that commercial crops may also benefit from the presence of noncrop flowers; however, the efficacy and economic benefits of sowing flower strips for crops remain relatively unstudied. In a study system that utilizes both wild and commercial pollinators, we test whether wildflower strips increase the number of visits to adjacent commercial strawberry crops by pollinating insects. We quantified this by experimentally sowing wildflower strips approximately 20 meters away from the crop and recording the number of pollinator visits to crops with, and without, flower strips. Between June and August 2013, we walked 292 crop transects at six farms in Scotland, recording a total of 2826 pollinators. On average, the frequency of pollinator visits was 25% higher for crops with adjacent flower strips compared to those without, with a combination of wild and commercial bumblebees (Bombus spp.) accounting for 67% of all pollinators observed. This effect was independent of other confounding effects, such as the number of flowers on the crop, date, and temperature. Synthesis and applications. This study provides evidence that soft fruit farmers can increase the number of pollinators that visit their crops by sowing inexpensive flower seed mixes nearby. By investing in this management option, farmers have the potential to increase and sustain pollinator populations over time

  10. Gender Differences in Cooperation: Experimental Evidence on High School Students

    PubMed Central

    Molina, J. Alberto; Giménez-Nadal, J. Ignacio; Cuesta, José A.; Gracia-Lazaro, Carlos; Moreno, Yamir; Sanchez, Angel

    2013-01-01

    The emergence of cooperation among unrelated human subjects is a long-standing conundrum that has been amply studied both theoretically and experimentally. Within the question, a less explored issue relates to the gender dependence of cooperation, which can be traced back to Darwin, who stated that "women are less selfish but men are more competitive". Indeed, gender has been shown to be relevant in several game theoretical paradigms of social cooperativeness, including prisoner's dilemma, snowdrift and ultimatum/dictator games, but there is no consensus as to which gender is more cooperative. We here contribute to this literature by analyzing the role of gender in a repeated Prisoners' Dilemma played by Spanish high-school students in both a square lattice and a heterogeneous network. While the experiment was conducted to shed light on the influence of networks on the emergence of cooperation, we benefit from the availability of a large dataset of more 1200 participants. We applied different standard econometric techniques to this dataset, including Ordinary Least Squares and Linear Probability models including random effects. All our analyses indicate that being male is negatively associated with the level of cooperation, this association being statistically significant at standard levels. We also obtain a gender difference in the level of cooperation when we control for the unobserved heterogeneity of individuals, which indicates that the gender gap in cooperation favoring female students is present after netting out this effect from other socio-demographics factors not controlled for in the experiment, and from gender differences in risk, social and competitive preferences. PMID:24367608

  11. Possible Noninvasive Biomarker of Eosinophilic Esophagitis: Clinical and Experimental Evidence.

    PubMed

    Venkateshaiah, Sathisha Upparahalli; Manohar, Murli; Verma, Alok K; Blecker, Uwe; Mishra, Anil

    2016-01-01

    Eosinophilic esophagitis (EoE) diagnosis and follow-up response to therapy is based on repeated endoscopies and histological examination for eosinophils/HPF. The procedure is invasive and risky in particular for the pediatric population. Presently, there is no highly sensitive and specific noninvasive blood test available to monitor the disease pathogenesis. Reports indicate the expression of PDL1 (CD274) on the eosinophils in allergic patients. Herein, we report that CD274-expressing and -nonexpressing eosinophils were detected in both examined pediatric and adult EoE patients. We show that CD274 expression on blood eosinophils and blood mRNA expression levels increase in the blood of EoE patients and decrease following treatment. These observations are consistent with the esophageal eosinophilia of before and after treatment in both examined patients. These two clinical and experimental analysis reports provide the possibility that the CD274 mRNA and CD274-expressing esinophil levels may be novel possible noninvasive biomarkers for EoE.

  12. Possible Noninvasive Biomarker of Eosinophilic Esophagitis: Clinical and Experimental Evidence

    PubMed Central

    Venkateshaiah, Sathisha Upparahalli; Manohar, Murli; Verma, Alok K.; Blecker, Uwe; Mishra, Anil

    2016-01-01

    Eosinophilic esophagitis (EoE) diagnosis and follow-up response to therapy is based on repeated endoscopies and histological examination for eosinophils/HPF. The procedure is invasive and risky in particular for the pediatric population. Presently, there is no highly sensitive and specific noninvasive blood test available to monitor the disease pathogenesis. Reports indicate the expression of PDL1 (CD274) on the eosinophils in allergic patients. Herein, we report that CD274-expressing and -nonexpressing eosinophils were detected in both examined pediatric and adult EoE patients. We show that CD274 expression on blood eosinophils and blood mRNA expression levels increase in the blood of EoE patients and decrease following treatment. These observations are consistent with the esophageal eosinophilia of before and after treatment in both examined patients. These two clinical and experimental analysis reports provide the possibility that the CD274 mRNA and CD274-expressing esinophil levels may be novel possible noninvasive biomarkers for EoE. PMID:27920662

  13. Measuring psychological resilience to disasters: are evidence-based indicators an achievable goal?

    PubMed Central

    2013-01-01

    Despite rising interest on the concept of societal resilience and its measurement, little has been done to provide operational indicators. Importantly, an evidence-based approach to assess the suitability of indicators remains unexplored. Furthermore few approaches that exist do not investigate indicators of psychological resilience, which is emerging as an important component of societal resilience to disasters. Disasters are events which overwhelm local capacities, often producing human losses, injury and damage to the affected communities. As climate hazards and disasters are likely to increase in the coming decades, strengthening the capacity of societies to withstand these shocks and recover quickly is vital. In this review, we search the Web of Knowledge to summarize the evidence on indicators of psychological resilience to disasters and provided a qualitative assessment of six selected studies. We find that an evidence-based approach using features from systematic reviews is useful to compile, select and assess the evidence and elucidate robust indicators. We conclude that strong social support received after a disaster is associated with an increased psychological resilience whereas a female gender is connected with a decrease in the likelihood of a resilient outcome. These results are consistent across disaster settings and cultures and are representative of approximately 13 million disaster-exposed civilians of adult age. An approach such as this that collects and evaluates evidence will allow indicators of resilience to be much more revealing and useful in the future. They will provide a robust basis to prioritize indicators to act upon through intersectoral policies and post-disaster public health interventions. PMID:24359448

  14. Measuring psychological resilience to disasters: are evidence-based indicators an achievable goal?

    PubMed

    Rodriguez-Llanes, Jose Manuel; Vos, Femke; Guha-Sapir, Debarati

    2013-12-20

    Despite rising interest on the concept of societal resilience and its measurement, little has been done to provide operational indicators. Importantly, an evidence-based approach to assess the suitability of indicators remains unexplored. Furthermore few approaches that exist do not investigate indicators of psychological resilience, which is emerging as an important component of societal resilience to disasters. Disasters are events which overwhelm local capacities, often producing human losses, injury and damage to the affected communities. As climate hazards and disasters are likely to increase in the coming decades, strengthening the capacity of societies to withstand these shocks and recover quickly is vital. In this review, we search the Web of Knowledge to summarize the evidence on indicators of psychological resilience to disasters and provided a qualitative assessment of six selected studies. We find that an evidence-based approach using features from systematic reviews is useful to compile, select and assess the evidence and elucidate robust indicators. We conclude that strong social support received after a disaster is associated with an increased psychological resilience whereas a female gender is connected with a decrease in the likelihood of a resilient outcome. These results are consistent across disaster settings and cultures and are representative of approximately 13 million disaster-exposed civilians of adult age. An approach such as this that collects and evaluates evidence will allow indicators of resilience to be much more revealing and useful in the future. They will provide a robust basis to prioritize indicators to act upon through intersectoral policies and post-disaster public health interventions.

  15. Performance Indicators in Math: Implications for Brief Experimental Analysis of Academic Performance

    ERIC Educational Resources Information Center

    VanDerheyden, Amanda M.; Burns, Matthew K.

    2009-01-01

    Brief experimental analysis (BEA) can be used to specify intervention characteristics that produce positive learning gains for individual students. A key challenge to the use of BEA for intervention planning is the identification of performance indicators (including topography of the skill, measurement characteristics, and decision criteria) that…

  16. Auger Recombination in Indium Gallium Nitride: Experimental Evidence

    NASA Astrophysics Data System (ADS)

    Krames, Michael

    2010-03-01

    Progress in InGaN-based light-emitting diode (LED) technology has resulted in white-light emitters with efficiencies far exceeding those of conventional light sources such as tungsten-filament-based incandescence and mercury-vapor based fluorescence. Indeed, by now efficacies exceeding 150 lumens per Watt for InGaN-based phosphor-converted white LEDs are claimed, which represent a 90% energy savings compared to the conventional incandescent (i.e., ``light bulb'') solution. However, these high performance levels are obtained under conditions of very low forward current-density for the InGaN LED and do not represent true operating conditions (nor cost-effective utilization) for the device. In order to reduce the cost (and thus increase market penetration of) solid-state lighting, more lumens per unit of semiconductor area are required which in practice necessitates higher drive current densities. Unfortunately, at these higher driver current densities, the internal quantum efficiency of InGaN-based LEDs is observed to decrease significantly. In the fall of 2007, researchers at the Advanced Laboratories of Philips Lumileds were the first to propose Auger recombination as the root-cause mechanism in InGaN which was behind this ``efficiency droop'' [1]. They further proposed to circumvent the problem by employing InGaN-based active region designs that maintain low carrier density, and demonstrated an LED device design that reaches a maximum quantum efficiency above 200 A/cm2, compared to ˜1-10 A/cm^2 for typical multiple-quantum-well heterostructures [2]. In this talk we will review the experimental evidence for Auger recombination in InGaN, beginning with the early work from 2007 and then considering additional work from more recent efforts to better understand the details behind this loss mechanism. [4pt] [1] Y. C. Shen, G. O. M"uller, S. Watanabe, N. F. Gardner, A. Munkholm, and M. R. Krames, ``Auger recombination in InGaN measured by photoluminescence'', Appl. Phys

  17. Plant-induced weathering of a basaltic rock: experimental evidence

    NASA Astrophysics Data System (ADS)

    Hinsinger, Philippe; Fernandes Barros, Omar Neto; Benedetti, Marc F.; Noack, Yves; Callot, Gabriel

    2001-01-01

    The active role of higher plants in the weathering of silicate minerals and rocks is still a question for debate. The present work aimed at providing experimental evidence of the important role of a range of crop plants in such processes. In order to quantitatively assess the possible effect of these diverse plant species on the weathering of a basaltic rock, two laboratory experiments were carried out at room temperature. These compared the amounts of elements released from basalt when leached with a dilute salt solution in the presence or absence of crop plants grown for up to 36 days. For Si, Ca, Mg, and Na, plants resulted in an increase in the release rate by a factor ranging from 1 to 5 in most cases. Ca and Na seemed to be preferentially released relative to other elements, suggesting that plagioclase dissolved faster than the other constituents of the studied basalt. Negligible amounts of Fe were released in the absence of plants as a consequence of the neutral pH and atmospheric pO 2 that were maintained in the leaching solution. However, the amounts of Fe released from basalt in the presence of plants were up to 100- to 500-fold larger than in the absence of plants, for banana and maize. The kinetics of dissolution of basalt in the absence of plants showed a constantly decreasing release rate over the whole duration of the experiment (36 days). No steady state value was reached both in the absence and presence of banana plants. However, in the latter case, the rates remained at a high initial level over a longer period of time (up to 15 days) before starting to decrease. For Fe, the maximum rate of release was reached beyond 4 days and this rate remained high up to 22 days of growth of banana. The possible mechanisms responsible for this enhanced release of elements from basalt in the presence of plants are discussed. Although these mechanisms need to be elucidated, the present results clearly show that higher plants can considerably affect the kinetics

  18. Convergent Evidence Scaling for Multiple Assessment Indicators: Conceptual Issues, Applications, and Technical Challenges

    ERIC Educational Resources Information Center

    Busse, R. T.; Elliott, Stephen N.; Kratochwill, Thomas R.

    2010-01-01

    The purpose of this article is to present Convergent Evidence Scaling (CES) as an emergent method for combining data from multiple assessment indicators. The CES method combines single-case assessment data by converging data gathered across multiple persons, settings, or measures, thereby providing an overall criterion-referenced outcome on which…

  19. Theoretical and Experimental Evidence for a Nodal Energy Gap in MgB2

    DTIC Science & Technology

    2017-02-17

    1   Theoretical and Experimental Evidence for a Nodal Energy Gap in MgB2 Y. Dan Agassia and Daniel E. Oatesb aConsultant, Jerusalem, Israel bMIT...the smaller of the two energy gaps in MgB2, the so-called  gap, contains nodal lines with a six-fold symmetry (i-wave). The model also indicates that...in MgB2 and the Coulomb repulsion. It is based on a phononic pairing mechanism and assumes no coupling between the two energy gaps in MgB2 at zero

  20. Evidence-based performance indicators of primary care for asthma: a modified RAND Appropriateness Method.

    PubMed

    To, Teresa; Guttmann, Astrid; Lougheed, M Diane; Gershon, Andrea S; Dell, Sharon D; Stanbrook, Matthew B; Wang, Chengning; McLimont, Susan; Vasilevska-Ristovska, Jovanka; Crighton, Eric J; Fisman, David N

    2010-12-01

    To develop evidence-based performance indicators that measure the quality of primary care for asthma. Cochrane Database of Systematic Reviews, MEDLINE, EMBASE and CINAHL for peer-reviewed articles published in 1998-2008 and five national/global asthma management guidelines. Articles with a focus on current asthma performance indicators recognized or used in community and primary care settings. Data extraction Modified RAND Appropriateness was used. The work described herein was conducted in Canada in 2008. Five clinician experts conducted the systematic literature review. Asthma-specific performance indicators were developed and the strength of supporting evidence summarized. A survey was created and mailed to 17 expert panellists of various disciplines, asking them to rate each indicator using a 9-point Likert scale. Percentage distribution of the Likert scores were generated and given to the panellists before a face-to-face meeting, which was held to assess consensus. At the meeting, they ranked all indicators based on their reliability, validity, availability and feasibility. Literature search yielded 1228 articles, of which 135 were used to generate 45 performance indicators in five domains: access to care, clinical effectiveness, patient centeredness, system integration and coordination and patient safety. The top five ranked indicators were: Asthma Education from Certified Asthma Educator, Pulmonary Function Monitoring, Asthma Control Monitoring, Controller Medication Use and Asthma Control. The top 15 ranked indicators are recommended for implementation in primary care to measure asthma care delivery, respiratory health outcomes and establish benchmarks for optimal health service delivery over time and across populations.

  1. Experimental Shock Transformation of Gypsum to Anhydrite: A New Low Pressure Regime Shock Indicator

    NASA Technical Reports Server (NTRS)

    Bell, Mary S.; Zolensky, Michael E.

    2011-01-01

    The shock behavior of gypsum is important in understanding the Cretaceous/Paleogene event and other terrestrial impacts that contain evaporite sediments in their targets (e.g., Mars Exploration Rover Spirit detected sulfate at Gusev crater, [1]). Most interest focuses on issues of devolatilization to quantify the production of SO2 to better understand its role in generating a temporary atmosphere and its effects on climate and biota [2,3]. Kondo and Ahrens [4] measured induced radiation emitted from single crystal gypsum shocked to 30 and 40 GPa. They observed greybody emission spectra corresponding to temperatures in the range of 3,000 to 4,000 K that are a factor of 2 to 10 times greater than calculated pressure-density energy equation of state temperatures (Hugoniot) and are high enough to melt gypsum. Chen et al. [5] reported results of shock experiments on anhydrite, gypsum, and mixtures of these phases with silica. Their observations indicated little or no devolatilization of anhydrite shocked to 42 GPa and that the fraction of sulfur, by mass, that degassed is approx.10(exp -2) of theoretical prediction. In another report of shock experiments on calcite, anhydrite, and gypsum, Badjukov et al. [6] observed only intensive plastic deformation in anhydrite shock loaded at 63 GPa, and gypsum converted to anhydrite when shock loaded at 56 GPa but have not experimentally shocked gypsum in a step-wise manner to constrain possible incipient transformation effects. Schmitt and Hornemann [7] shock loaded anhydrite and quartz to a peak pressure of 60 GPa and report the platy anhydrite grains were completely pseudomorphed by small crystallized anhydrite grains. However, no evidence of interaction between the two phases could be observed and they suggested that recrystallization of anhydrite grains is the result of a solid-state transformation. They concluded that significant decomposition of anhydrite requires shock pressures higher than 60 GPa. Gupta et al. [8

  2. Comparison of ordered and disordered silicon nanowire arrays: experimental evidence of photonic crystal modes.

    PubMed

    Dhindsa, Navneet; Saini, Simarjeet S

    2016-05-01

    We experimentally compared the reflectance between ordered and disordered silicon nanowires to observe the evidence of photonic crystal modes. For similar diameters, the resonance peaks for the ordered nanowires at a spacing of 400 nm was at a shorter wavelength than the disordered nanowires, consistent to the excitation of photonic crystal modes. Furthermore, the resonant wavelength didn't shift while changing the density of the disordered nanowires, whereas there was a significant shift observed in the ordered ones. At an ordered spacing of 800 nm, the resonance wavelength approached that of the disordered structures, indicating that the ordered structures were starting to behave like individual waveguides. To our knowledge, this is the first direct experimental observation of photonic crystal modes in vertical periodic silicon nanowire arrays.

  3. Confounding by indication in non-experimental evaluation of vaccine effectiveness: the example of prevention of influenza complications

    PubMed Central

    Hak, E; Verheij, T.; Grobbee, D; Nichol, K; Hoes, A

    2002-01-01

    Randomised allocation of vaccine or placebo is the preferred method to assess the effects of the vaccine on clinical outcomes relevant to the individual patient. In the absence of phase 3 trials using clinical end points, notably post-influenza complications, alternative non-experimental designs to evaluate vaccine effects or safety are often used. The application of these designs may, however, lead to invalid estimates of vaccine effectiveness or safety. As patients with poor prognosis are more likely to be immunised, selection for vaccination is confounded by patient factors that are also related to clinical end points. This paper describes several design and analytical methods aimed at limiting or preventing this confounding by indication in non-experimental studies. In short, comparison of study groups with similar prognosis, restriction of the study population, and statistical adjustment for dissimilarities in prognosis are important tools and should be considered. Only if the investigator is able to show that confounding by indication is sufficiently controlled for, results of a non-experimental study may be of use to direct an evidence based vaccine policy. PMID:12461118

  4. Further evidence for periodontal disease as a risk indicator for adverse pregnancy outcomes.

    PubMed

    Turton, Mervyn; Africa, Charlene W J

    2017-06-01

    Although there is increasing evidence to suggest an association between periodontal disease and adverse pregnancy outcomes, the issue remains controversial. This study tested the hypothesis that periodontal disease is a risk indicator for preterm delivery of low-birthweight infants. The study sample comprised 443 pregnant women with a mean (± standard deviation) age of 24.13 (±5.30) years. At first visit, maternal oral health status was assessed by the measurement of probing pocket depth and clinical attachment loss, and periodontal status was graded as absent, mild, moderate or severe. An association was sought between pregnancy outcomes and maternal periodontal status. While controlling for other factors, significant associations were found between pregnancy outcomes and maternal periodontal index scores. This study provides further evidence that periodontal disease is a risk indicator for adverse pregnancy outcomes. © 2016 FDI World Dental Federation.

  5. Intraoperative radiotherapy in early stage breast cancer: potential indications and evidence to date

    PubMed Central

    Kirby, A M

    2015-01-01

    Following early results of recent studies of intraoperative radiotherapy (IORT) in the adjuvant treatment of patients with early breast cancer, the clinical utility of IORT is a subject of much recent debate within the breast oncology community. This review describes the intraoperative techniques available, the potential indications and the evidence to date pertaining to local control and toxicity. We also discuss any implications for current practice and future research. PMID:25734489

  6. Bilateral oligopoly in pollution permit markets: experimental evidence

    USDA-ARS?s Scientific Manuscript database

    We experimentally investigate behavior in a bilateral oligopoly using a supply function equilibria model (Klemper and Meyer 1989; Hendricks and McAfee 2010; Malueg and Yates 2009). We focus on the role that market size and the degree of firm heterogeneity have on the market equilibrium. Our results ...

  7. Development and evaluation of evidence-informed quality indicators for adult injury care.

    PubMed

    Santana, Maria J; Stelfox, Henry T

    2014-01-01

    To develop and evaluate evidence-informed quality indicators of adult injury care. Injury is a leading cause of morbidity and mortality, but there is a lack of consensus regarding how to evaluate injury care. Using a modification of the RAND/UCLA Appropriateness Methodology, a panel of 19 injury and quality of care experts serially rated and revised quality indicators identified from a systematic review of the literature and international audit of trauma center quality improvement practices. The quality indicators developed by the panel were sent to 133 verified trauma centers in the United States, Canada, Australia, and New Zealand for evaluation. A total of 84 quality indicators were rated and revised by the expert panel over 4 rounds of review producing 31 quality indicators of structure (n=5), process (n=21), and outcome (n=5), designed to assess the safety (n=8), effectiveness (n=17), efficiency (n=6), timeliness (n=16), equity (n=2), and patient-centeredness (n=1) of injury care spanning prehospital (n=8), hospital (n=19), and posthospital (n=2) care and secondary injury prevention (n=1). A total of 101 trauma centers (76% response rate) rated the indicators (1=strong disagreement, 9=strong agreement) as targeting important health improvements (median score 9, interquartile range [IQR] 8-9), easy to interpret (median score 8, IQR 8-9), easy to implement (median score 8, IQR 7-8), and globally good indicators (median score 8, IQR 8-9). Thirty-one evidence-informed quality indicators of adult injury care were developed, shown to have content validity, and can be used as performance measures to guide injury care quality improvement practices.

  8. Evaluating the use of key performance indicators to evidence the patient experience.

    PubMed

    McCance, Tanya; Hastings, Jack; Dowler, Hilda

    2015-11-01

    To test eight person-centred key performance indicators and the feasibility of an appropriate measurement framework as an approach to evidencing the patient experience. The value of measuring the quality of patient care is undisputed in the international literature, however, the type of measures that can be used to generate data that is meaningful for practice continues to be debated. This paper offers a different perspective to the 'measurement' of the nursing and midwifery contribution to the patient experience. Fourth generation evaluation was the methodological approach used to evaluate the implementation of the key performance indicators and measurement framework across three participating organisations involving nine practice settings. Data were collected by repeated use of claims, concerns and issues with staff working across nine participating sites (n = 18) and the senior executives from the three partner organisations (n = 12). Data were collected during the facilitated sessions with stakeholders and analysed in conjunction with the data generated from the measurement framework. The data reveal the inherent value placed on the evidence generated from the implementation of the key performance indicators as reflected in the following themes: measuring what matters; evidencing the patient experience; engaging staff; a focus for improving practice; and articulating and demonstrating the positive contribution of nursing and midwifery. The implementation of the key performance indicators and the measurement framework has been effective in generating evidence that demonstrates the patient experience. The nature of the data generated not only privileges the patient voice but also offers feedback to nurses and midwives that can inform the development of person-centred cultures. The use of these indicators will produce evidence of patient experience that can be used by nurse and midwives to celebrate and further inform person-centred practice. © 2015 John

  9. Experimental evidence of interhemispheric transport from airborne carbon monoxide measurements

    NASA Technical Reports Server (NTRS)

    Newell, R. E.; Gauntner, D. J.

    1979-01-01

    During the period 28-30 October 1977, a Pan American 747-SP aircraft flew around the world with an automated instrument package that included measurements of atmospheric CO made every 4 sec. The flight path extended from San Francisco, over the North Pole to London, south to Capetown, over the South Pole to Auckland, and back to San Francisco. The data collected show large changes with longitude, which are interpreted as direct evidence of interhemispheric mixing. Possible sources for CO are discussed.

  10. Do Incentives Exert Undue Influence on Survey Participation? Experimental Evidence

    PubMed Central

    Singer, Eleanor; Couper, Mick P.

    2008-01-01

    Monetary incentives are increasingly used to help motivate survey participation. Research Ethics Committees have begun to ask whether, and under what conditions, the use of monetary incentives to induce participation might be coercive. The article reports research from an online vignette-based study bearing on this question, concluding that at present the evidence suggests that larger incentives do not induce research participants to accept higher risks than they would be unwilling to accept with smaller ones. PMID:19385770

  11. Do incentives exert undue influence on survey participation? Experimental evidence.

    PubMed

    Singer, Eleanor; Couper, Mick P

    2008-09-01

    MONETARY INCENTIVES ARE INCREASINGLY used to help motivate survey participation. Research Ethics Committees have begun to ask whether, and under what conditions, the use of monetary incentives to induce participation might be coercive. The article reports research from an online vignette-based study bearing on this question, concluding that at present the evidence suggests that larger incentives do not induce research participants to accept higher risks than they would be unwilling to accept with smaller ones.

  12. Experimental evidence for the cardioprotective effects of red wine

    PubMed Central

    Das, Samarjit; Santani, Dev D; Dhalla, Naranjan S

    2007-01-01

    Both epidemiological and experimental studies have revealed that intake of wine, particularly red wine, in moderation protects cardiovascular health; however, the experimental basis for such an action is not fully understood. Because all types of red wine contain varying amounts of alcohol and antioxidants, it is likely that the cardioprotective effect of red wine is due to both these constituents. In view of its direct action on the vascular smooth muscle cells, alcohol may produce coronary vasodilation in addition to attenuating oxidative stress by its action on the central nervous system. The antioxidant components of red wine may provide cardioprotection by their ability to reduce oxidative stress in the heart under different pathological conditions. Mild-to-moderate red wine consumption improves cardiac function in the ischemic myocardium through the protection of endothelial function, the expression of several cardioprotective oxidative stress-inducible proteins, as well as the activation of adenosine receptors and nitrous oxide synthase mechanisms. PMID:18650973

  13. Experimental evidence for solitary waves in the middle atmosphere

    NASA Astrophysics Data System (ADS)

    Widdel, H.-U.

    1991-09-01

    Results are reported from a foil-chaff experimental study of solitary waves using an in situ motion sensor which responds instantly to changes in air velocity. The signal-to-noise ratio of a radar echo from a chaff cloud which was released at a height of 105 km is illustrated. The initial velocity of the foils relative to the ambient air given by the spin of a rocket is decreased by the aerodynamic drag forces, which are proportional to the velocity and air density. After a certain time the foils come practically to rest, they cease to spread, and the radar return cross section then stabilizes on a fairly constant value which it keeps unless atmospheric motions change it through further spreading of the foils. A selection of effects which are difficult to observe and to follow in detail by other experimental methods is presented, and data are adduced which suggest that a solitary wave was observed.

  14. Experimental evidence for formation mechanism of regular circular fringes

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Zhu, R.; Wang, G.; Wang, P.; Li, H.; Zhang, W.; Ren, G.

    2016-10-01

    Laser active suppressing jamming is one of the most effective technologies to cope with optoelectric imaging systems. In the process of carrying out laser disturbing experiment, regular circular fringes often appeared on the detector, besides laser spot converging by optical system. First of all, the formation of circular fringes has been experimentally investigated by using a simple converging lens to replace the complex optical system. Moreover, circular fringes have been simulated based on the interference theory of coherent light. The coherence between the experimental phenomena and the simulated results showed that the formation mechanism of regular circular fringes was the interference effect between reflected light by back surface of lens and directly refractive light on the detector. At last, the visibility of circular fringes has been calculated from 0.05 to 0.22 according to the current plating standard of lens surface and manufacture technique of optoelectric detector.

  15. Laparoscopic surgery for benign and malign diseases of the digestive system: indications, limitations, and evidence.

    PubMed

    Küper, Markus Alexander; Eisner, Friederike; Königsrainer, Alfred; Glatzle, Jörg

    2014-05-07

    The laparoscopic technique was introduced in gastrointestinal surgery in the mid 1980s. Since then, the development of this technique has been extraordinary. Triggered by technical innovations (stapling devices or coagulation/dissecting devices), nowadays any type of gastrointestinal resection has been successfully performed laparoscopically and can be performed laparoscopically dependent on the patient's condition. This summary gives an overview over 30 years of laparoscopic surgery with focus on today's indications and evidence. Main indications remain the more common procedures, e.g., appendectomy, cholecystectomy, bariatric procedures or colorectal resections. For all these indications, the laparoscopic approach has become the gold standard with less perioperative morbidity. Regarding oncological outcome there have been several high-quality randomized controlled trials which demonstrated equivalency between laparoscopic and open colorectal resections. Less common procedures like esophagectomy, oncological gastrectomy, liver and pancreatic resections can be performed successfully as well by an experienced surgeon. However, the evidence for these special indications is poor and a general recommendation cannot be given. In conclusion, laparoscopic surgery has revolutionized the field of gastrointestinal surgery by reducing perioperative morbidity without disregarding surgical principles especially in oncological surgery.

  16. Indications for medical compression stockings in venous and lymphatic disorders: An evidence-based consensus statement.

    PubMed

    Rabe, Eberhard; Partsch, Hugo; Hafner, Juerg; Lattimer, Christopher; Mosti, Giovanni; Neumann, Martino; Urbanek, Tomasz; Huebner, Monika; Gaillard, Sylvain; Carpentier, Patrick

    2017-01-01

    Objective Medical compression stockings are a standard, non-invasive treatment option for all venous and lymphatic diseases. The aim of this consensus document is to provide up-to-date recommendations and evidence grading on the indications for treatment, based on evidence accumulated during the past decade, under the auspices of the International Compression Club. Methods A systematic literature review was conducted and, using PRISMA guidelines, 51 relevant publications were selected for an evidence-based analysis of an initial 2407 unrefined results. Key search terms included: 'acute', CEAP', 'chronic', 'compression stockings', 'compression therapy', 'lymph', 'lymphatic disease', 'vein' and 'venous disease'. Evidence extracted from the publications was graded initially by the panel members individually and then refined at the consensus meeting. Results Based on the current evidence, 25 recommendations for chronic and acute venous disorders were made. Of these, 24 recommendations were graded as: Grade 1A (n = 4), 1B (n = 13), 1C (n = 2), 2B (n = 4) and 2C (n = 1). The panel members found moderately robust evidence for medical compression stockings in patients with venous symptoms and prevention and treatment of venous oedema. Robust evidence was found for prevention and treatment of venous leg ulcers. Recommendations for stocking-use after great saphenous vein interventions were limited to the first post-interventional week. No randomised clinical trials are available that document a prophylactic effect of medical compression stockings on the progression of chronic venous disease (CVD). In acute deep vein thrombosis, immediate compression is recommended to reduce pain and swelling. Despite conflicting results from a recent study to prevent post-thrombotic syndrome, medical compression stockings are still recommended. In thromboprophylaxis, the role of stockings in addition to anticoagulation is limited. For the maintenance phase of lymphoedema

  17. Reactions to the use of evidence-based performance indicators in primary care: a qualitative study

    PubMed Central

    Wilkinson, E.; McColl, A.; Exworthy, M.; Roderick, P.; Smith, H.; Moore, M.; Gabbay, J.

    2000-01-01

    Objectives—To investigate reactions to the use of evidence-based cardiovascular and stroke performance indicators within one primary care group. Design—Qualitative analysis of semi-structured interviews. Setting—Fifteen practices from a primary care group in southern England. Participants—Fifty two primary health care professionals including 29 general practitioners, 11 practice managers, and 12 practice nurses. Main outcome measures—Participants' perceptions towards and actions made in response to these indicators. The barriers and facilitators in using these indicators to change practice. Results—Barriers to the use of the indicators were their data quality and their technical specifications, including definitions of diseases such as heart failure and the threshold for interventions such as blood pressure control. Nevertheless, the indicators were sufficiently credible to prompt most of those in primary care teams to reflect on some aspect of their performance. The most common response was to improve data quality through increased or improved accuracy of recording. There was a lack of a coordinated team approach to decision making. Primary care teams placed little importance on the potential for performance indicators to identify and address inequalities in services between practices. The most common barrier to change was a lack of time and resources to act upon indicators. Conclusion—For the effective implementation of national performance indicators there are many barriers to overcome at individual, practice, and primary care group levels. Additional training and resources are required for improvements in data quality and collection, further education of all members of primary care teams, and measures to foster organisational development within practices. Unless these barriers are addressed, performance indicators could initially increase apparent variation between practices. Key Words: performance indicators; primary care; primary care groups

  18. Assessing the Relationship between Vector Indices and Dengue Transmission: A Systematic Review of the Evidence

    PubMed Central

    Bowman, Leigh R.; Runge-Ranzinger, Silvia; McCall, P. J.

    2014-01-01

    Background Despite doubts about methods used and the association between vector density and dengue transmission, routine sampling of mosquito vector populations is common in dengue-endemic countries worldwide. This study examined the evidence from published studies for the existence of any quantitative relationship between vector indices and dengue cases. Methodology/Principal Findings From a total of 1205 papers identified in database searches following Cochrane and PRISMA Group guidelines, 18 were included for review. Eligibility criteria included 3-month study duration and dengue case confirmation by WHO case definition and/or serology. A range of designs were seen, particularly in spatial sampling and analyses, and all but 3 were classed as weak study designs. Eleven of eighteen studies generated Stegomyia indices from combined larval and pupal data. Adult vector data were reported in only three studies. Of thirteen studies that investigated associations between vector indices and dengue cases, 4 reported positive correlations, 4 found no correlation and 5 reported ambiguous or inconclusive associations. Six out of 7 studies that measured Breteau Indices reported dengue transmission at levels below the currently accepted threshold of 5. Conclusions/Significance There was little evidence of quantifiable associations between vector indices and dengue transmission that could reliably be used for outbreak prediction. This review highlighted the need for standardized sampling protocols that adequately consider dengue spatial heterogeneity. Recommendations for more appropriately designed studies include: standardized study design to elucidate the relationship between vector abundance and dengue transmission; adult mosquito sampling should be routine; single values of Breteau or other indices are not reliable universal dengue transmission thresholds; better knowledge of vector ecology is required. PMID:24810901

  19. Strategic sophistication of individuals and teams. Experimental evidence

    PubMed Central

    Sutter, Matthias; Czermak, Simon; Feri, Francesco

    2013-01-01

    Many important decisions require strategic sophistication. We examine experimentally whether teams act more strategically than individuals. We let individuals and teams make choices in simple games, and also elicit first- and second-order beliefs. We find that teams play the Nash equilibrium strategy significantly more often, and their choices are more often a best response to stated first order beliefs. Distributional preferences make equilibrium play less likely. Using a mixture model, the estimated probability to play strategically is 62% for teams, but only 40% for individuals. A model of noisy introspection reveals that teams differ from individuals in higher order beliefs. PMID:24926100

  20. INSTITUTIONS AND BEHAVIOR: EXPERIMENTAL EVIDENCE ON THE EFFECTS OF DEMOCRACY

    PubMed Central

    Bó, Pedro Dal; Foster, Andrew; Putterman, Louis

    2013-01-01

    A novel experiment is used to show that the effect of a policy on the level of cooperation is greater when it is chosen democratically by the subjects than when it is exogenously imposed. In contrast to the previous literature, our experimental design allows us to control for selection effects (e.g. those who choose the policy may be affected differently by it). Our finding implies that democratic institutions may affect behavior directly in addition to having effects through the choice of policies. Our findings have implications for the generalizability of the results of randomized policy interventions. PMID:25076785

  1. Multiple Openings and Competitiveness of Forward Markets: Experimental Evidence.

    PubMed

    Ferreira, José Luis; Kujal, Praveen; Rassenti, Stephen

    2016-01-01

    We test the competition enhancing effect of selling forward in experimental Cournot duopoly and quadropoly with multiple forward markets. We find that two forward periods yields competitive outcomes and that the results are very close to the predicted theoretical results for quantity setting duopolies and quadropolies. Our experiments lend strong support to the hypothesis that forward markets are competition enhancing. We then test a new market that allows for endogenously determined indefinitely many forward periods that only close when sellers coordinate on selling a zero amount in a forward market. We find that the outcomes under an endogenous close rule are also very competitive. These results hold for both duopolies and quadropolies.

  2. Selection of experimental strawberry (Fragaria x ananassa) hybrids based on selection indices.

    PubMed

    Vieira, S D; de Souza, D C; Martins, I A; Ribeiro, G H M R; Resende, L V; Ferraz, A K L; Galvão, A G; de Resende, J T V

    2017-03-08

    The strawberry (Fragaria x ananassa Dutch.), is the only vegetable belonging to the rosacea family. All strawberry species have now emerged from wild species and belong to the genus Fragaria, being that this genus presents more than 45 described species, and only 11 are considered natural species. Due to the octoploid nature of strawberry and its variability after hybridization, selecting one or more characters may result in unfavorable genotypes and even the exclusion of promising ones, because negative genetic correlations have been observed among them that cause inefficient selection. Therefore, the objective of this study was to verify the efficiency of selection indices in selecting experimental strawberry hybrids for in natura consumption and processing. Seven commercial cultivars and 103 hybrids were used, which were obtained from populations derived from their crossings. The experiment was conducted in augmented blocks, in which four agronomical traits (total mass, amount of commercial fruit, amount of noncommercial fruit, and average fruit mass) and seven physical-chemical traits (soluble solids, soluble solids:titratable acidity ratio, total sugars, total pectin, vigor, and internal and external coloration) were evaluated. For hybrid selection, the following indices were used: Mulamba and Mock (1978), Smith (1936), Hazel (1943), and genotype-ideotype, which selected 20% of the genotypes evaluated. The three indices selected about 9% of the hybrids. The selection of two experimental hybrids (89 and 495) and the use of selection indices resulted in larger estimates of selection gains. The Mulamba and Mock (1978), Smith (1936), and Hazel (1943) indices had the highest percentage of gains on selection, and are therefore recommended for the selection of strawberry clones.

  3. The fungal colonisation of rock-art caves: experimental evidence.

    PubMed

    Jurado, Valme; Fernandez-Cortes, Angel; Cuezva, Soledad; Laiz, Leonila; Cañaveras, Juan Carlos; Sanchez-Moral, Sergio; Saiz-Jimenez, Cesareo

    2009-09-01

    The conservation of rock-art paintings in European caves is a matter of increasing interest. This derives from the bacterial colonisation of Altamira Cave, Spain and the recent fungal outbreak of Lascaux Cave, France-both included in the UNESCO World Heritage List. Here, we show direct evidence of a fungal colonisation of rock tablets in a testing system exposed in Altamira Cave. After 2 months, the tablets, previously sterilised, were heavily colonised by fungi and bacteria. Most fungi isolated were labelled as entomopathogens, while the bacteria were those regularly identified in the cave. Rock colonisation was probably promoted by the dissolved organic carbon supplied with the dripping and condensation waters and favoured by the displacement of aerosols towards the interior of the cave, which contributed to the dissemination of microorganisms. The role of arthropods in the dispersal of spores may also help in understanding fungal colonisation. This study evidences the fragility of rock-art caves and demonstrates that microorganisms can easily colonise bare rocks and materials introduced into the cavity.

  4. The fungal colonisation of rock-art caves: experimental evidence

    NASA Astrophysics Data System (ADS)

    Jurado, Valme; Fernandez-Cortes, Angel; Cuezva, Soledad; Laiz, Leonila; Cañaveras, Juan Carlos; Sanchez-Moral, Sergio; Saiz-Jimenez, Cesareo

    2009-09-01

    The conservation of rock-art paintings in European caves is a matter of increasing interest. This derives from the bacterial colonisation of Altamira Cave, Spain and the recent fungal outbreak of Lascaux Cave, France—both included in the UNESCO World Heritage List. Here, we show direct evidence of a fungal colonisation of rock tablets in a testing system exposed in Altamira Cave. After 2 months, the tablets, previously sterilised, were heavily colonised by fungi and bacteria. Most fungi isolated were labelled as entomopathogens, while the bacteria were those regularly identified in the cave. Rock colonisation was probably promoted by the dissolved organic carbon supplied with the dripping and condensation waters and favoured by the displacement of aerosols towards the interior of the cave, which contributed to the dissemination of microorganisms. The role of arthropods in the dispersal of spores may also help in understanding fungal colonisation. This study evidences the fragility of rock-art caves and demonstrates that microorganisms can easily colonise bare rocks and materials introduced into the cavity.

  5. Experimental evidence of ericoid mycorrhizal potential within Serendipitaceae (Sebacinales).

    PubMed

    Vohník, Martin; Pánek, Matěj; Fehrer, Judith; Selosse, Marc-André

    2016-11-01

    The Sebacinales are a monophyletic group of ubiquitous hymenomycetous mycobionts which form ericoid and orchid mycorrhizae, ecto- and ectendomycorrhizae, and nonspecific root endophytic associations with a wide spectrum of plants. However, due to the complete lack of fungal isolates derived from Ericaceae roots, the Sebacinales ericoid mycorrhizal (ErM) potential has not yet been tested experimentally. Here, we report for the first time isolation of a serendipitoid (formerly Sebacinales Group B) mycobiont from Ericaceae which survived in pure culture for several years. This allowed us to test its ability to form ericoid mycorrhizae with an Ericaceae host in vitro, to describe its development and colonization pattern in host roots over time, and to compare its performance with typical ErM fungi and other serendipitoids derived from non-Ericaceae hosts. Out of ten serendipitoid isolates tested, eight intracellularly colonized Vaccinium hair roots, but only the Ericaceae-derived isolate repeatedly formed typical ericoid mycorrhiza morphologically identical to ericoid mycorrhiza commonly found in naturally colonized Ericaceae, but yet different from ericoid mycorrhiza formed in vitro by the prominent ascomycetous ErM fungus Rhizoscyphus ericae. One Orchidaceae-derived isolate repeatedly formed abundant hyaline intracellular microsclerotia morphologically identical to those occasionally found in naturally colonized Ericaceae, and an isolate of Serendipita (= Piriformospora) indica produced abundant intracellular chlamydospores typical of this species. Our results confirm for the first time experimentally that some Sebacinales can form ericoid mycorrhiza, point to their broad endophytic potential in Ericaceae hosts, and suggest possible ericoid mycorrhizal specificity in Serendipitaceae.

  6. Experimental evidence of directivity-enhancing mechanisms in nonlinear lattices

    NASA Astrophysics Data System (ADS)

    Ganesh, R.; Gonella, Stefano

    2017-02-01

    In this letter, we experimentally investigate the directional characteristics of propagating, finite-amplitude wave packets in lattice materials, with an emphasis on the functionality enhancement due to the nonlinearly generated higher harmonics. To this end, we subject a thin, periodically perforated sheet to out-of-plane harmonic excitations, and we design a systematic measurement and data processing routine that leverages the full-wavefield reconstruction capabilities of a laser vibrometer to precisely delineate the effects of nonlinearity. We demonstrate experimentally that the interplay of dispersion, nonlinearity, and modal complexity which is involved in the generation and propagation of higher harmonics gives rise to secondary wave packets with characteristics that conform to the dispersion relation of the corresponding linear structure. Furthermore, these nonlinearly generated wave features display modal and directional characteristics that are complementary to those exhibited by the fundamental harmonic, thus resulting in an augmentation of the functionality landscape of the lattice. These results provide a proof of concept for the possibility to engineer the nonlinear wave response of mechanical metamaterials through a geometric and topological design of the unit cell.

  7. Fostering Early Math Comprehension: Experimental Evidence from Paraguay

    ERIC Educational Resources Information Center

    Naslund-Hadley, Emma; Parker, Susan W.; Hernandez-Agramonte, Juan Manuel

    2014-01-01

    Research indicates that preschool children need to learn pre-math skills to build a foundation for primary- and secondary-level mathematics. This paper presents the results from the early stages of a pilot mathematics program implemented in Cordillera, Paraguay. In a context of significant gaps in teacher preparation and pedagogy, the program uses…

  8. Experimental Evidence of the Gardner Phase in a Granular Glass

    NASA Astrophysics Data System (ADS)

    Seguin, A.; Dauchot, O.

    2016-11-01

    Analyzing the dynamics of a vibrated bidimensional packing of bidisperse granular disks below jamming, we provide evidence of a Gardner phase deep into the glass phase. To do so, we perform several compression cycles within a given realization of the same glass and show that the particles select different average vibrational positions at each cycle, while the neighborhood structure remains unchanged. The separation between the cages obtained for different compression cycles plateaus with an increasing packing fraction, while the mean square displacement steadily decreases. This phenomenology is strikingly similar to that reported in recent numerical observations when entering the Gardner phase, for a mean-field model of glass as well as for hard spheres in finite dimension. We also characterize the distribution of the cage order parameters. Here we note several differences from the numerical results, which could be attributed to activated processes and cage heterogeneities.

  9. Experimental Evidence of the Gardner Phase in a Granular Glass.

    PubMed

    Seguin, A; Dauchot, O

    2016-11-25

    Analyzing the dynamics of a vibrated bidimensional packing of bidisperse granular disks below jamming, we provide evidence of a Gardner phase deep into the glass phase. To do so, we perform several compression cycles within a given realization of the same glass and show that the particles select different average vibrational positions at each cycle, while the neighborhood structure remains unchanged. The separation between the cages obtained for different compression cycles plateaus with an increasing packing fraction, while the mean square displacement steadily decreases. This phenomenology is strikingly similar to that reported in recent numerical observations when entering the Gardner phase, for a mean-field model of glass as well as for hard spheres in finite dimension. We also characterize the distribution of the cage order parameters. Here we note several differences from the numerical results, which could be attributed to activated processes and cage heterogeneities.

  10. Experimental evidence for hillslope control of landscape scale

    NASA Astrophysics Data System (ADS)

    Sweeney, K. E.; Roering, J. J.; Ellis, C.

    2015-07-01

    Landscape evolution theory suggests that climate sets the scale of landscape dissection by modulating the competition between diffusive processes that sculpt convex hillslopes and advective processes that carve concave valleys. However, the link between the relative dominance of hillslope and valley transport processes and landscape scale is difficult to demonstrate in natural landscapes due to the episodic nature of erosion. Here, we report results from laboratory experiments combining diffusive and advective processes in an eroding landscape. We demonstrate that rainsplash-driven disturbances in our experiments are a robust proxy for hillslope transport, such that increasing hillslope transport efficiency decreases drainage density. Our experimental results demonstrate how the coupling of climate-driven hillslope- and valley-forming processes, such as bioturbation and runoff, dictates the scale of eroding landscapes.

  11. Multiple Openings and Competitiveness of Forward Markets: Experimental Evidence

    PubMed Central

    Ferreira, José Luis; Kujal, Praveen; Rassenti, Stephen

    2016-01-01

    We test the competition enhancing effect of selling forward in experimental Cournot duopoly and quadropoly with multiple forward markets. We find that two forward periods yields competitive outcomes and that the results are very close to the predicted theoretical results for quantity setting duopolies and quadropolies. Our experiments lend strong support to the hypothesis that forward markets are competition enhancing. We then test a new market that allows for endogenously determined indefinitely many forward periods that only close when sellers coordinate on selling a zero amount in a forward market. We find that the outcomes under an endogenous close rule are also very competitive. These results hold for both duopolies and quadropolies. PMID:27442516

  12. GEOMORPHOLOGY. Experimental evidence for hillslope control of landscape scale.

    PubMed

    Sweeney, K E; Roering, J J; Ellis, C

    2015-07-03

    Landscape evolution theory suggests that climate sets the scale of landscape dissection by modulating the competition between diffusive processes that sculpt convex hillslopes and advective processes that carve concave valleys. However, the link between the relative dominance of hillslope and valley transport processes and landscape scale is difficult to demonstrate in natural landscapes due to the episodic nature of erosion. Here, we report results from laboratory experiments combining diffusive and advective processes in an eroding landscape. We demonstrate that rainsplash-driven disturbances in our experiments are a robust proxy for hillslope transport, such that increasing hillslope transport efficiency decreases drainage density. Our experimental results demonstrate how the coupling of climate-driven hillslope- and valley-forming processes, such as bioturbation and runoff, dictates the scale of eroding landscapes. Copyright © 2015, American Association for the Advancement of Science.

  13. Non-Respiratory Indications for Polysomnography and Related Procedures in Children: An Evidence-Based Review

    PubMed Central

    Kotagal, Suresh; Nichols, Cynthia D.; Grigg-Damberger, Madeleine M.; Marcus, Carole L.; Witmans, Manisha B.; Kirk, Valerie G.; D'Andrea, Lynn A.; Hoban, Timothy F.

    2012-01-01

    Objective: This evidence-based review provides a systematic and comprehensive review of the literature regarding the utility of polysomnography for the evaluation of non-respiratory sleep disorders in children including hypersomnias, parasomnias, sleep-related movement disorders, and sleep in other special populations. Methods: A task force of pediatric sleep medicine experts performed a systematic review of the literature regarding the use of polysomnography for non-respiratory sleep disorders in children. They identified and graded 76 papers as evidence. Results: The main results include (1) polysomnography combined with the multiple sleep latency test is useful for evaluating disorders of excessive somnolence to objectively quantify sleepiness. The results have to be interpreted with consideration of the pubertal stage and regularity of the sleep patterns of the child; (2) polysomnography is indicated in children with parasomnias or sleep related movement disorders who have a high likelihood of having obstructive sleep apnea (OSA); (3) polysomnography is not routinely indicated in children with enuresis unless there is a high likelihood of OSA; (4) polysomnography can be helpful in evaluating children with restless legs syndrome (RLS) and when periodic limb movement disorder (PLMD) is suspected. Conclusions: These findings suggest that, in children with non-respiratory sleep disorders, polysomnography should be a part of a comprehensive sleep evaluation in selected circumstances to determine the nature of the events in more detail or when the suspicion of OSA is relatively high. Citation: Kotagal S; Nichols CD; Grigg-Damberger MM; Marcus CL; Witmans MB; Kirk VG; D'Andrea LA; Hoban TF. Non-respiratory indications for polysomnography and related procedures in children: an evidence-based review. SLEEP 2012;35(11):1451-1466. PMID:23115394

  14. Mechanisms of methylmercury-induced neurotoxicity: evidence from experimental studies

    PubMed Central

    Farina, Marcelo; Rocha, João B. T.; Aschner, Michael

    2011-01-01

    Neurological disorders are common, costly, and can cause enduring disability. Although mostly unknown, a few environmental toxicants are recognized causes of neurological disorders and subclinical brain dysfunction. One of the best known neurotoxins is methylmercury (MeHg), a ubiquitous environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. In the aquatic environment, MeHg is accumulated in fish, which represent a major source of human exposure. Although several episodes of MeHg poisoning have contributed to the understanding of the clinical symptoms and histological changes elicited by this neurotoxicant in humans, experimental studies have been pivotal in elucidating the molecular mechanisms that mediate MeHg-induced neurotoxicity. The objective of this mini-review is to summarize data from experimental studies on molecular mechanisms of MeHg-induced neurotoxicity. While the full picture has yet to be unmasked, in vitro approaches based on cultured cells, isolated mitochondria and tissue slices, as well as in vivo studies based mainly on the use of rodents, point to impairment in intracellular calcium homeostasis, alteration of glutamate homeostasis and oxidative stress as important events in MeHg-induced neurotoxicity. The potential relationship among these events is discussed, with particular emphasis on the neurotoxic cycle triggered by MeHg-induced excitotoxicity and oxidative stress. The particular sensitivity of the developing brain to MeHg toxicity, the critical role of selenoproteins and the potential protective role of selenocompounds are also discussed. These concepts provide the biochemical bases to the understanding of MeHg neurotoxicity, contributing to the discovery of endogenous and exogenous molecules that counteract such toxicity and provide efficacious means for ablating this vicious cycle. PMID:21683713

  15. Experimental evidence for sibling recognition in Common Terns (Sterna hirundo)

    USGS Publications Warehouse

    Burger, J.; Gochfeld, M.; Boarman, W.I.

    1988-01-01

    Young Common Terns (Sterna hirundo) did not respond preferentially to calls of siblings at 8 and 9 days of age, but did so by 12 days of age. In experiments with and without visual isolation, and with use of playback, we demonstrated a tendency to approach sibling begging calls. This differential response indicated sibling-recognition occurred, was based on experience, and involved vocal cues.

  16. Intraday volatility spillovers between spot and futures indices: Evidence from the Korean stock market

    NASA Astrophysics Data System (ADS)

    Kang, Sang Hoon; Cheong, Chongcheul; Yoon, Seong-Min

    2013-04-01

    This study provides empirical evidence of the relationship between spot and futures markets in Korea. In particular, the study focuses on the volatility spillover relationship between spot and futures markets by using three high-frequency (10 min, 30 min, and 1 h time-scales) intraday data sets of KOSPI 200 spot and futures contracts. The results indicate a strong bi-directional causal relationship between futures and spot markets, suggesting that return volatility in the spot market can influence that in the futures market and vice versa. Thus, the results indicate that new information is reflected in futures and spot markets simultaneously. This bi-directional causal relationship provides market participants with important guidance on understanding the intraday information transmission between the two markets. Thus, on a given trading day, there may be sudden and sharp increases or decreases in return volatility in the Korean stock market as a result of positive feedback and synchronization of spot and futures markets.

  17. [Experimental evidence for motoric rehabilitation in lymphoedema (author's transl)].

    PubMed

    Leduc, A; Lievens, P

    1979-01-01

    The authors distinguish three modalities of lymphtransport in lymphoedema. 1. Enhanced evacuation by existing lymphatics. 2. Enhanced evacuation by regenerated lymphatics. 3. Enhanced evacuation by lympho-lymphatic anastomoses. Experiments with 500 white mice indicate that the resorption of lymphoedema is increased by guided compression, although some manipulations must be performed with care, especially when regenerated lymphatics are present. The lymphatic flow in a limb is also enhanced by a special drainage technique at the proximal part of it. Likewise the lymph can be manipulated into the opposite limb by anastomotic channels after unilateral lymphadenectomy.

  18. Experimental Evidence for Static Charge Density Waves in Iron Oxypnictides.

    PubMed

    Martinelli, A; Manfrinetti, P; Provino, A; Genovese, A; Caglieris, F; Lamura, G; Ritter, C; Putti, M

    2017-02-03

    In this Letter we report high-resolution synchrotron x-ray powder diffraction and transmission electron microscope analysis of Mn-substituted LaFeAsO samples, demonstrating that a static incommensurate modulated structure develops across the low-temperature orthorhombic phase, whose modulation wave vector depends on the Mn content. The incommensurate structural distortion is likely originating from a charge-density-wave instability, a periodic modulation of the density of conduction electrons associated with a modulation of the atomic positions. Our results add a new component in the physics of Fe-based superconductors, indicating that the density wave ordering is charge driven.

  19. Experimental Evidence for Static Charge Density Waves in Iron Oxypnictides

    NASA Astrophysics Data System (ADS)

    Martinelli, A.; Manfrinetti, P.; Provino, A.; Genovese, A.; Caglieris, F.; Lamura, G.; Ritter, C.; Putti, M.

    2017-02-01

    In this Letter we report high-resolution synchrotron x-ray powder diffraction and transmission electron microscope analysis of Mn-substituted LaFeAsO samples, demonstrating that a static incommensurate modulated structure develops across the low-temperature orthorhombic phase, whose modulation wave vector depends on the Mn content. The incommensurate structural distortion is likely originating from a charge-density-wave instability, a periodic modulation of the density of conduction electrons associated with a modulation of the atomic positions. Our results add a new component in the physics of Fe-based superconductors, indicating that the density wave ordering is charge driven.

  20. Implicit negotiation beliefs and performance: experimental and longitudinal evidence.

    PubMed

    Kray, Laura J; Haselhuhn, Michael P

    2007-07-01

    The authors argue that implicit negotiation beliefs, which speak to the expected malleability of negotiating ability, affect performance in dyadic negotiations. They expected negotiators who believe negotiating attributes are malleable (incremental theorists) to outperform negotiators who believe negotiating attributes are fixed (entity theorists). In Study 1, they gathered evidence of convergent and discriminant validity for the implicit negotiation belief construct. In Study 2, they examined the impact of implicit beliefs on the achievement goals that negotiators pursue. In Study 3, they explored the causal role of implicit beliefs on negotiation performance by manipulating negotiators' implicit beliefs within dyads. They also identified perceived ability as a moderator of the link between implicit negotiation beliefs and performance. In Study 4, they measured negotiators' beliefs in a classroom setting and examined how these beliefs affected negotiation performance and overall performance in the course 15 weeks later. Across all performance measures, incremental theorists outperformed entity theorists. Consistent with the authors' hypotheses, incremental theorists captured more of the bargaining surplus and were more integrative than their entity theorist counterparts, suggesting implicit theories are important determinants of how negotiators perform. Implications and future directions are discussed.

  1. Experimental evidence for efficient hydroxyl radical regeneration in isoprene oxidation

    NASA Astrophysics Data System (ADS)

    Fuchs, H.; Hofzumahaus, A.; Rohrer, F.; Bohn, B.; Brauers, T.; Dorn, H.-P.; Häseler, R.; Holland, F.; Kaminski, M.; Li, X.; Lu, K.; Nehr, S.; Tillmann, R.; Wegener, R.; Wahner, A.

    2013-12-01

    Most pollutants in the Earth's atmosphere are removed by oxidation with highly reactive hydroxyl radicals. Field measurements have revealed much higher concentrations of hydroxyl radicals than expected in regions with high loads of the biogenic volatile organic compound isoprene. Different isoprene degradation mechanisms have been proposed to explain the high levels of hydroxyl radicals observed. Whether one or more of these mechanisms actually operates in the natural environment, and the potential impact on climate and air quality, has remained uncertain. Here, we present a complete set of measurements of hydroxyl and peroxy radicals collected during isoprene-oxidation experiments carried out in an atmospheric simulation chamber, under controlled atmospheric conditions. We detected significantly higher concentrations of hydroxyl radicals than expected based on model calculations, providing direct evidence for a strong hydroxyl radical enhancement due to the additional recycling of radicals in the presence of isoprene. Specifically, our findings are consistent with the unimolecular reactions of isoprene-derived peroxy radicals postulated by quantum chemical calculations. Our experiments suggest that more than half of the hydroxyl radicals consumed in isoprene-rich regions, such as forests, are recycled by these unimolecular reactions with isoprene. Although such recycling is not sufficient to explain the high concentrations of hydroxyl radicals observed in the field, we conclude that it contributes significantly to the oxidizing capacity of the atmosphere in isoprene-rich regions.

  2. Experimental evidence for the influence of cognitions on compulsive buying.

    PubMed

    McQueen, Paul; Moulding, Richard; Kyrios, Michael

    2014-12-01

    Compulsive buying is a disabling condition, where individuals are unable to resist or control their buying behavior, leading to substantial social and financial problems. Cognitive models implicate the role of beliefs as one factor in buying behavior, for example, "this item is unique and will help me improve my life". This study experimentally examined the contribution of such beliefs to the disorder, in individuals who compulsively buy (N = 18) and in non-clinical controls (N = 17). Participants were presented with photographs of idiosyncratically appealing and unappealing items, in the context of imagined scenarios that either minimized or maximized aspects relevant to hypothesized "compulsive buying beliefs" (i.e., beliefs that acquisition can compensate for negative feelings, beliefs regarding uniqueness and lost opportunities, and emotional reasons for buying). It was found that individuals who compulsively buy demonstrated stronger urges to purchase than control participants, regardless of context, but the overall strength of these urges was responsive to manipulations of beliefs about consumer items said to be associated with compulsive buying. The main limitation of the study was a small sample size, potentially reducing power. Nonetheless, these findings provide insights into the processes underlying compulsive phenomena, in particular supporting the role of cognitions in compulsive buying. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Experimental evidence for mobility/immobility of metals in peat.

    PubMed

    Novak, Martin; Zemanova, Leona; Voldrichova, Petra; Stepanova, Marketa; Adamova, Marie; Pacherova, Petra; Komarek, Arnost; Krachler, Michael; Prechova, Eva

    2011-09-01

    The biogeochemical cycles of most toxic metals have been significantly altered by anthropogenic activities. Anaerobic, rain-fed organic soils are believed to record historical changes in atmospheric pollution. Suspected postdepositional mobility of trace elements, however, hinders the usefulness of peat bogs as pollution archives. To lower this uncertainty, we quantified the mobility of six trace metals in peat during an 18-month field manipulation. A replicated, reciprocal peat transplant experiment was conducted between a heavily polluted and a relatively unpolluted peatland, located 200 km apart in the Czech Republic (Central Europe). Both peatlands were Sphagnum-derived, lawn-dominated, and had water table close to the surface. A strikingly different behavior was observed for two groups of elements. Elements of group I, Fe and Mn, adjusted their abundances and vertical patterns to the host site, showing an extremely high degree of mobility. In contrast, elements of group II, Pb, Cu, Zn, and Ti, preserved their original vertical patterns at the host site, showing a high degree of immobility. Our experimental results suggest that not just lead, but also copper and zinc concentration profiles in peat are a reliable archive of temporal pollution changes within a wide pH range (2.5-5.8).

  4. Insight of scent: experimental evidence of olfactory capabilities in the wandering albatross (Diomedea exulans).

    PubMed

    Mardon, J; Nesterova, A P; Traugott, J; Saunders, S M; Bonadonna, F

    2010-02-15

    Wandering albatrosses routinely forage over thousands of kilometres of open ocean, but the sensory mechanisms used in the food search itself have not been completely elucidated. Recent telemetry studies show that some spatial behaviours of the species are consistent with the 'multimodal foraging strategy' hypothesis which proposes that birds use a combination of olfactory and visual cues while foraging at sea. The 'multimodal foraging strategy' hypothesis, however, still suffers from a lack of experimental evidence, particularly regarding the olfactory capabilities of wandering albatrosses. As an initial step to test the hypothesis, we carried out behavioural experiments exploring the sensory capabilities of adult wandering albatrosses at a breeding colony. Three two-choice tests were designed to investigate the birds' response to olfactory and visual stimuli, individually or in combination. Perception of the different stimuli was assessed by comparing the amount of exploration directed towards an 'experimental' display or a 'control' display. Our results indicate that birds were able to perceive the three types of stimulus presented: olfactory, visual and combined. Moreover, olfactory and visual cues were found to have additional effects on the exploratory behaviours of males. This simple experimental demonstration of reasonable olfactory capabilities in the wandering albatross supports the 'multimodal foraging strategy' and is consistent with recent hypotheses of the evolutionary history of procellariiforms.

  5. Experimental Evidence of Mechanical Isotropy in Porcine Lung Parenchyma

    PubMed Central

    Weed, Benjamin; Patnaik, Sourav; Rougeau-Browning, Mary; Brazile, Bryn; Liao, Jun; Prabhu, Raj; Williams, Lakiesha N.

    2015-01-01

    Pulmonary injuries are a major source of morbidity and mortality associated with trauma. Trauma includes injuries associated with accidents and falls as well as blast injuries caused by explosives. The prevalence and mortality of these injuries has made research of pulmonary injury a major priority. Lungs have a complex structure, with multiple types of tissues necessary to allow successful respiration. The soft, porous parenchyma is the component of the lung which contains the alveoli responsible for gas exchange. Parenchyma is also the portion which is most susceptible to traumatic injury. Finite element simulations are an important tool for studying traumatic injury to the human body. These simulations rely on material properties to accurately recreate real world mechanical behaviors. Previous studies have explored the mechanical properties of lung tissues, specifically parenchyma. These studies have assumed material isotropy but, to our knowledge, no study has thoroughly tested and quantified this assumption. This study presents a novel methodology for assessing isotropy in a tissue, and applies these methods to porcine lung parenchyma. Briefly, lung parenchyma samples were dissected so as to be aligned with one of the three anatomical planes, sagittal, frontal, and transverse, and then subjected to compressive mechanical testing. Stress-strain curves from these tests were statistically compared by a novel method for differences in stresses and strains at percentages of the curve. Histological samples aligned with the anatomical planes were also examined by qualitative and quantitative methods to determine any differences in the microstructural morphology. Our study showed significant evidence to support the hypothesis that lung parenchyma behaves isotropically.

  6. [Is it possible a bioethics based on the experimental evidence?].

    PubMed

    Pastor, Luis Miguel

    2013-01-01

    For years there are different types of criticism about principialist bioethics. One alternative that has been proposed is to introduce empirical evidence within the bioethical discourse to make it less formal, less theoretical and closer to reality. In this paper we analyze first in synthetic form diverse alternative proposals to make an empirical bioethics. Some of them are strongly naturalistic while others aim to provide empirical data only for correct or improve bioethical work. Most of them are not shown in favor of maintaining a complete separation between facts and values, between what is and what ought to be. With different nuances these proposals of moderate naturalism make ethical judgments depend normative social opinion resulting into a certain social naturalism. Against these proposals we think to make a bioethics in that relates the empirical facts with ethical duties, we must rediscover empirical reality of human action. Only from it and, in particular, from the activity of discernment that makes practical reason, when judged on the object of his action, it is possible to integrate the mere descriptive facts with ethical judgments of character prescriptive. In conclusion we think that it is not possible to perform bioethics a mode of empirical science, as this would be contrary to natural reason, leading to a sort of scientific reductionism. At the same time we believe that empirical data are important in the development of bioethics and to enhance and improve the innate ability of human reason to discern good. From this discernment could develop a bioethics from the perspective of ethical agents themselves, avoiding the extremes of an excessive normative rationalism, accepting empirical data and not falling into a simple pragmatism.

  7. Origin of new genes: evidence from experimental and computational analyses.

    PubMed

    Long, Manyuan; Deutsch, Michael; Wang, Wen; Betrán, Esther; Brunet, Frédéric G; Zhang, Jianming

    2003-07-01

    Exon shuffling is an essential molecular mechanism for the formation of new genes. Many cases of exon shuffling have been reported in vertebrate genes. These discoveries revealed the importance of exon shuffling in the origin of new genes. However, only a few cases of exon shuffling were reported from plants and invertebrates, which gave rise to the assertion that the intron-mediated recombination mechanism originated very recently. We focused on the origin of new genes by exon shuffling and retroposition. We will first summarize our experimental work, which revealed four new genes in Drosophila, plants, and humans. These genes are 10(6) to 10(8) million years old. The recency of these genes allows us to directly examine the origin and evolution of genes in detail. These observations show firstly the importance of exon shuffling and retroposition in the rapid creation of new gene structures. They also show that the resultant chimerical structures appearing as mosaic proteins or as retroposed coding structures with novel regulatory systems, often confer novel functions. Furthermore, these newly created genes appear to have been governed by positive Darwinian selection throughout their history, with rapid changes of amino acid sequence and gene structure in very short periods of evolution. We further analyzed the distribution of intron phases in three non-vertebrate species, Drosophila melanogaster, Caenorhabditis elegans, and Arabidosis thaliana, as inferred from their genome sequences. As in the case of vertebrate genes, we found that intron phases in these species are unevenly distributed with an excess of phase zero introns and a significant excess of symmetric exons. Both findings are consistent with the requirements for the molecular process of exon shuffling. Thus, these non-vertebrate genomes may have also been strongly impacted by exon shuffling in general.

  8. Experimental evidence for the reducibility of multifragment emission probabilities

    SciTech Connect

    Wozniak, G.J.; Tso, K.; Phair, L.

    1995-01-01

    Multifragmentation has been studied for {sup 36}Ar-induced reactions on a {sup 197}Au target at E/A = 80 and 110 MeV and for {sup 129}Xe-induced reactions on several targets ({sup nat}Cu, {sup 89}y, {sup 165}ho, {sup 197}Au) and E/A = 40, 50 and 60 MeV. The probability of emitting n intermediate-mass-fragments is shown to be binomial at each transversal energy and reducible to an elementary binary probability p. For each target and at each bombarding energy, this probability p shows a thermal nature by giving linear Arrhenius plots. For the {sup 129}Xe-induced reactions, a nearly universal linear Arrhenius plot is observed at each bombarding energy, indicating a large degree of target independence.

  9. Dietary fibre and colon cancer: epidemiologic and experimental evidence.

    PubMed Central

    Reddy, B S

    1980-01-01

    Epidemiologic studies have identified two dietary factors, a relatively high intake of fat and a relatively low intake of fibre, that are associated with colon cancer in humans. However, a recent study has shown a low risk of large bowel cancer in a rural Finnish population with a high dietary intake of fat, but also a high intake of fibre. Observations in humans and studies in animals have indicated that dietary fibre may protect against colon carcinogenesis by binding bile acids in the intestinal tract, by a direct effect on the colonic mucosa and by an indirect effect on the metabolism of carcinogens. The strength of protection varies with the type of fibre. PMID:6254626

  10. Experimental evidence for offspring learning in parent-offspring communication.

    PubMed

    Kedar, H; Rodríguez-Gironés, M A; Yedvab, S; Winkler, D W; Lotem, A

    2000-09-07

    The offspring of birds and mammals solicit food from their parents by a combination of movements and vocalizations that have come to be known collectively as 'begging'. Recently, begging has most often been viewed as an honest signal of offspring need. Yet, if offspring learn to adjust their begging efforts to the level that rewards them most, begging intensities may also reflect offsprings' past experience rather than their precise current needs. Here we show that bird nestlings with equal levels of need can learn to beg at remarkably different levels. These experiments with hand-raised house sparrows (Passer domesticus) indicated that chicks learn to modify begging levels within a few hours. Moreover, we found that the begging postures of hungry chicks in natural nests are correlated with the average postures that had previously yielded them parental feedings. Such learning challenges parental ability to assess offspring needs and may require that, in response, parents somehow filter out learned differences in offspring signals.

  11. Experimental evidence for paternal effects on offspring growth rate in Arctic charr (Salvelinus alpinus)

    PubMed Central

    Eilertsen, Eirik Mack; Bårdsen, Bård-Jørgen; Liljedal, Ståle; Rudolfsen, Geir; Folstad, Ivar

    2008-01-01

    Sexual selection theory predicts that females should choose males that signal viability and quality. However, few studies have found fitness benefits among females mating with highly ornamented males. Here, we use Arctic charr (Salvelinus alpinus), a teleost fish with no parental care, to investigate whether females could gain fitness benefits by mating with highly ornamented and large-sized males. Carotenoid-based coloration signalled by males during spawning is believed to be an indicator of good genes for this species. Paternal effects on offspring size (body length and dry body mass) were examined experimentally by crossing eggs and sperm in vitro from 12 females and 24 males in a split-brood design and raising larvae to 30 days past hatching. We clearly demonstrated that there was a relationship between offspring size and paternal coloration. However, a negative interaction between paternal length and coloration was evident for offspring length, indicating that positive effects of paternal coloration were only present for smaller males. Thus, the red spawning coloration of the male Arctic charr seems to be an indicator of good genes, but the effect of paternal coloration on offspring length, an indicator of ‘offspring quality’, is size dependent. PMID:18782751

  12. Experimental evidence for paternal effects on offspring growth rate in Arctic charr (Salvelinus alpinus).

    PubMed

    Eilertsen, Eirik Mack; Bårdsen, Bård-Jørgen; Liljedal, Ståle; Rudolfsen, Geir; Folstad, Ivar

    2009-01-07

    Sexual selection theory predicts that females should choose males that signal viability and quality. However, few studies have found fitness benefits among females mating with highly ornamented males. Here, we use Arctic charr (Salvelinus alpinus), a teleost fish with no parental care, to investigate whether females could gain fitness benefits by mating with highly ornamented and large-sized males. Carotenoid-based coloration signalled by males during spawning is believed to be an indicator of good genes for this species. Paternal effects on offspring size (body length and dry body mass) were examined experimentally by crossing eggs and sperm in vitro from 12 females and 24 males in a split-brood design and raising larvae to 30 days past hatching. We clearly demonstrated that there was a relationship between offspring size and paternal coloration. However, a negative interaction between paternal length and coloration was evident for offspring length, indicating that positive effects of paternal coloration were only present for smaller males. Thus, the red spawning coloration of the male Arctic charr seems to be an indicator of good genes, but the effect of paternal coloration on offspring length, an indicator of 'offspring quality', is size dependent.

  13. Field and experimental evidence for competition's role in phenotypic divergence.

    PubMed

    Pfennig, David W; Rice, Amber M; Martin, Ryan A

    2007-02-01

    Resource competition has long been viewed as a major cause of phenotypic divergence within and between species. Theory predicts that divergence arises because natural selection favors individuals that are phenotypically dissimilar from their competitors. Yet, there are few conclusive tests of this key prediction. Drawing on data from both natural populations and a controlled experiment, this paper presents such a test in tadpoles of two species of spadefoot toads (Spea bombifrons and S. multiplicata). These two species show exaggerated divergence in trophic morphology where they are found together (mixed-species ponds) but not where each is found alone (pure-species ponds), suggesting that they have undergone ecological character displacement. Moreover, in pure-species ponds, both species exhibit resource polymorphism. Using body size as a proxy for fitness, we found that in pure-species ponds disruptive selection favors extreme trophic phenotypes in both species, suggesting that intraspecific competition for food promotes resource polymorphism. In mixed-species ponds, by contrast, we found that trophic morphology was subject to stabilizing selection in S. multiplicata and directional selection in S. bombifrons. A controlled experiment revealed that the more similar an S. multiplicata was to its S. bombifrons tankmate in resource use, the worse was its performance. These results indicate that S. multiplicata individuals that differ from S. bombifrons would be selectively favored in competition. Our data therefore demonstrate how resource competition between phenotypically similar individuals can drive divergence between them. Moreover, our results indicate that how competition contributes to such divergence may be influenced not only by the degree to which competitors overlap in resource use, but also by the abundance and quality of resources. Finally, our finding that competitively mediated disruptive selection may promote resource polymorphism has potentially

  14. Interplay between yawning and vigilance: a review of the experimental evidence.

    PubMed

    Guggisberg, Adrian G; Mathis, Johannes; Hess, Christian W

    2010-01-01

    Yawning is a phylogenetically old behavior of ubiquitous occurrence. The origin and function of this conspicuous phenomenon have been subject to speculation for centuries. A widely held hypothesis posits that yawning increases the arousal level during sleepiness; thus, providing a homeostatic regulation of vigilance. This chapter reviews experimental data on the relationship between yawning and vigilance that allow testing of the components and predictions of this hypothesis. Behavioral studies and electroencephalographic (EEG) recordings of brain activity before and after yawning have provided consistent evidence that yawning occurs during states of low vigilance; thus, substantiating the notion that it is provoked by sleepiness. However, studies analyzing autonomic nervous activity and EEG-based indices of vigilance in yawning subjects did not find specific autonomic activations or increased arousal levels after yawning. The data therefore do not support an arousing effect of yawning or a role in regulation of vigilance or autonomic tone. Copyright 2010 S. Karger AG, Basel.

  15. Animal traditions: experimental evidence of learning by imitation in an unlikely animal.

    PubMed

    Galef, Bennett G

    2010-07-13

    A new field study provides the first experimental evidence of learning by imitation in a free-living animal and demonstrates that social learning can maintain two behavioral traditions in a single population.

  16. Orbital blowout fractures: experimental evidence for the pure hydraulic theory.

    PubMed

    Rhee, John S; Kilde, John; Yoganadan, Narayan; Pintar, Frank

    2002-01-01

    The mechanism of injury and the underlying biomechanics of orbital blowout fractures remain controversial. The "hydraulic" theory proposes that a generalized increased orbital content pressure results in direct compression and fracturing of the thin orbital bone. To examine the pure hydraulic mechanism of injury by eliminating the factor of globe-to-wall contact and its possible contribution to fracture thresholds and patterns. Five fresh human cadaver specimens were used for the study. In each cadaver head, 1 orbit was prepared to mimic the normal physiologic condition by increasing the hypotony of the cadaver globe to normal intraocular pressure (15-20 mm Hg) with intravitreous injection of isotonic sodium chloride solution (saline). The second orbit served as a "hydraulic control," whereby the globe and orbital contents were exenterated and replaced by a saline-filled balloon at physiologic intraocular pressure. A 1-kg pendulum measuring 2.5 cm in diameter was used to strike the cadaver heads. Drop heights ranged from 0.2 m to 1.1 m (1960 mJ to 10 780 mJ energy). Each head was struck twice, once to each orbit. Direct visualization, high-speed videography, and computed tomographic scans were used to determine injury patterns at various heights between the 2 orbits. A fracture threshold was found at a drop height of 0.3 m (2940 mJ). Fracture severity and displacement increased with incremental increases in drop height (energy). Fracture displacement, with herniation of orbital contents, was obtained at heights above 0.5 m (4900 mJ). Isolated orbital floor fractures were obtained at lower heights, with medial wall fractures occurring in conjunction with floor fractures at higher energies (> or =6860 mJ). The globe intact side and balloon (hydraulic control) side showed nearly identical fracture patterns and levels of displacement at each drop height. This study provides support for the "hydraulic" theory and evidence against the role of direct globe-to-wall contact

  17. Health effects of trans-fatty acids: experimental and observational evidence.

    PubMed

    Mozaffarian, D; Aro, A; Willett, W C

    2009-05-01

    acids, respectively. The differential effects of specific TFA isomers may be important but are less well established. The available evidence indicates that trans-18:1 and particularly trans-18:2 isomers have stronger CHD effects than trans-16:1 isomers. The limited data suggest that the experimental effects of ruminant and industrial TFA are similar when consumed in similar quantities, but very few persons consume such high levels of ruminant TFA, and observational studies do not support adverse CHD effects of ruminant TFA in amounts actually consumed. Controlled trials and observational studies provide concordant evidence that consumption of TFA from partially hydrogenated oils adversely affects multiple cardiovascular risk factors and contributes significantly to increased risk of CHD events. The public health implications of ruminant TFA consumption appear much more limited. The effects of specific TFA isomers require further investigation.

  18. Blood flow in an experimental rat brain tumor by tissue equilibration and indicator fractionation.

    PubMed

    Graham, M M; Spence, A M; Abbott, G L; O'Gorman, L; Muzi, M

    1987-01-01

    The tissue equilibration technique (Kety) was compared with the indicator fractionation technique for the measurement of blood flow to normal brain and an experimental brain tumor in the rat. The tumor was a cloned astrocytic glioma implanted in the cerebral hemisphere of F-344 rats. I-125 Iodoantipyrine, using a rising infusion for one minute, was used for the tissue equilibration technique. C-14 butanol, injected as a bolus 8 seconds before sacrifice, was used for the indicator fractionation technique. Samples were assayed using liquid scintillation counting and the iodoantipyrine results were regressed against the butanol results. For normal tissue R = 0.832, SEE = 0.115 ml/g/min, and Slope = 0.626. For tumor R = 0.796, SEE = 0.070 ml/g/min, and Slope = 0.441. The iodoantipyrine tissue/blood partition coefficient for normal hemisphere (gray and white matter) was 0.861 +/-0.037 (SD) and for tumor was 0.876 +/-0.042. The indicator fractionation technique with C-14 butanol underestimated blood flow in a consistent manner, probably because of incomplete extraction, early washout of activity from tissue and from evaporation of butanol during processing. Our experiments revealed no differences between tumor and normal brain tissue that might invalidate the comparison of iodoantipyrine blood flow results in brain tumors and surrounding normal brain.

  19. Effects of Nicotine During Pregnancy: Human and Experimental Evidence

    PubMed Central

    Wickström, R

    2007-01-01

    Prenatal exposure to tobacco smoke is a major risk factor for the newborn, increasing morbidity and even mortality in the neonatal period but also beyond. As nicotine addiction is the factor preventing many women from smoking cessation during pregnancy, nicotine replacement therapy (NRT) has been suggested as a better alternative for the fetus. However, the safety of NRT has not been well documented, and animal studies have in fact pointed to nicotine per se as being responsible for a multitude of these detrimental effects. Nicotine interacts with endogenous acetylcholine receptors in the brain and lung, and exposure during development interferes with normal neurotransmitter function, thus evoking neurodevelopmental abnormalities by disrupting the timing of neurotrophic actions. As exposure to pure nicotine is quite uncommon in pregnant women, very little human data exist aside from the vast literature on prenatal exposure to tobacco smoke. The current review discusses recent findings in humans on effects on the newborn of prenatal exposure to pure nicotine and non-smoke tobacco. It also reviews the neuropharmacological properties of nicotine during gestation and findings in animal experiments that offer explanations on a cellular level for the pathogenesis of such prenatal drug exposure. It is concluded that as findings indicate that functional nAChRs are present very early in neuronal development, and that activation at this stage leads to apoptosis and mitotic abnormalities, a total abstinence from all forms of nicotine should be advised to pregnant women for the entirety of gestation. PMID:19305804

  20. Experimental evidence for offspring learning in parent-offspring communication.

    PubMed Central

    Kedar, H; Rodríguez-Gironés, M A; Yedvab, S; Winkler, D W; Lotem, A

    2000-01-01

    The offspring of birds and mammals solicit food from their parents by a combination of movements and vocalizations that have come to be known collectively as 'begging'. Recently, begging has most often been viewed as an honest signal of offspring need. Yet, if offspring learn to adjust their begging efforts to the level that rewards them most, begging intensities may also reflect offsprings' past experience rather than their precise current needs. Here we show that bird nestlings with equal levels of need can learn to beg at remarkably different levels. These experiments with hand-raised house sparrows (Passer domesticus) indicated that chicks learn to modify begging levels within a few hours. Moreover, we found that the begging postures of hungry chicks in natural nests are correlated with the average postures that had previously yielded them parental feedings. Such learning challenges parental ability to assess offspring needs and may require that, in response, parents somehow filter out learned differences in offspring signals. PMID:12233768

  1. Stochastic solutions of Navier-Stokes equations: an experimental evidence.

    PubMed

    Djurek, Ivan; Djurek, Danijel; Petosić, Antonio

    2010-12-01

    An electrodynamic loudspeaker has been operated in anharmonic regime indicated by the nonlinear ordinary differential equation when spring constant γ in restoring term, as well as, viscoelasticity of the membrane material, increases with displacement. For driving currents in the range of 2.8-3.3 A, doubling of the vibration period appears, while for currents in the range of 3.3-3.6 A, multiple sequences of subharmonic vibrations begin with f/4 and 3f/4. An application of currents higher than 3.6 A results in a spectrum, characteristic for the chaotic state. The loudspeaker was then operated in a closed chamber, and subharmonic vibrations disappeared by an evacuation. Subsequent injection of air revoked them again at ∼ 120 mbar (Re(')=476) when air viscous forces dominate the Morse convection. At 430 mbar (Re=538) single vibration state was restored, and the phenomenon is in an agreement with prediction of the five mode truncation procedure applied to the Navier-Stokes equations describing a two-dimensional incompressible fluid. © 2010 American Institute of Physics.

  2. Experimental evidence against transmission of Hepatozoon canis by Ixodes ricinus.

    PubMed

    Giannelli, Alessio; Ramos, Rafael Antonio Nascimento; Dantas-Torres, Filipe; Mencke, Norbert; Baneth, Gad; Otranto, Domenico

    2013-09-01

    Hepatozoon canis is among the most widespread tick-borne protozoa infecting domestic and wild carnivores. Its distribution is related to the occurrence of its major vector, the brown dog tick Rhipicephalus sanguineus. However, the role of Ixodes ricinus as a vector of H. canis has been hypothesized. In the present study, the development of H. canis was investigated in I. ricinus and R. sanguineus nymphs collected from a naturally infested dog. All I. ricinus ticks examined (n=133) were negative by cytological examination at days 20, 30, and 90 post collection, although H. canis DNA was detected in one nymph at day 20 and in 2 nymphs at day 30 post collection. On the other hand, H. canis sporogony was documented by cytology, and H. canis DNA was detected by PCR in R. sanguineus at day 30 post collection. These results indicate that H. canis sporogony does not occur in I. ricinus, but in R. sanguineus, suggesting that I. ricinus does not act as a vector of H. canis.

  3. Frost-weathering on Mars: experimental evidence for peroxide formation.

    PubMed

    Huguenin, R L; Miller, K J; Harwood, W S

    1979-12-01

    A laboratory study of the interaction of H2O frost with samples of the minerals olivine (Mg,Fe)2SiO4 and pyroxene (Mg,Fe)SiO3 at -11 degrees C to -22 degrees C revealed that an acidic oxidant was produced. Exposure of the frost-treated minerals to liquie H2O produced a sudden drop in pH and resulted in the production of copious O2(g) (as much as approximately 10(20) molecules g-1). Exposure of frost-treated samples to 5 ml of 0.1M HCOONa solution resulted in the rapid oxidation of up to 43% of the formate to CO2(g). These reactions were qualitatively similar to the chemical activity observed during the active cycles of the Viking lander Gas Exchange and Labeled Release Biology experiments. Attempts to identify the oxidant by chemical indicators were inconclusive, but they tentatively suggested that chemisorbed hydrogen peroxide may have formed. The formation of chemisorbed peroxide could be explained as a byproduct of the chemical reduction of the mineral. The following model was proposed. H+ was incorporated into the mineral from surface frost. This would have left behind a residual of excess OH-(ads) (relative to surface H+). Electrons were then stripped from the surface OH-(ads) (due to the large repulsive potential between neighboring OH-(ads)) and incorporated into the crystal to restore charge balance and produce a chemical reduction of the mineral. The resultant surface hydroxyl radicals could then have combined to form the more stable chemisorbed hydrogen peroxide species. While the chemisorbed peroxide should be relatively stable at low temperatures, it should tend to decay to O(ads)+ H2O(g) at higher temperatures with an activation energy of greater than or approximately 34 kcal mole-1. This is consistent with the long-term storage and sterilization behavior of the Viking soil oxidants. It is possible that as little as 0.1--1% frost-weathered material in the martian soil could have produced the unusual chemical activity that occurred during the Viking Gas

  4. Price discrimination in essential medicines: evidence from International Drug Price Indicator Guide data.

    PubMed

    Hanlon, Michael; Zhang, Raymond

    2013-03-01

    Few data are available on what donors, governments and other implementing organisations pay for the medicines they procure. To partly address this shortcoming, we analyse transactions of pharmaceuticals on the WHO's essential medicines list. Our objective was to identify the determinants of prices paid for these drugs. We used data from the 2008 version of the International Drug Price Indicator Guide. We normalised transactions by representing their value as a 'price per daily dose'. We used a mixed-effects regression model to quantify the impact of observable characteristics on prices paid. We present evidence of first-degree price discrimination in the market for essential medicines. We find that as a country's per capita wealth doubles, prices paid for the same pharmaceutical increase by 33%. These data indicate that purchasing agents from wealthier countries pay more for essential medicines, all factors constant. This behaviour is not a form of development assistance for health but rather is indicative of inefficient markets in which buyers' lack of information enables suppliers to charge higher prices than they could otherwise.

  5. Are glendonites reliable indicators of cold conditions? Evidence from the Lower Cretaceous of Spitsbergen

    NASA Astrophysics Data System (ADS)

    Vickers, Madeleine; Price, Gregory; Watkinson, Matthew; Jerrett, Rhodri

    2017-04-01

    Glendonites are pseudomorphs after the mineral ikaite, and have been found in marine sediments throughout geological time. Ikaite is a metastable, hydrated form of calcium carbonate, which is only stable under specific conditions: between -2 and +5 °C, and with high alkalinity and phosphate concentrations. Glendonites are often associated with cold climates due to the strong temperature control on ikaite growth, and the coincidence in the geological record with episodes of global cooling. Glendonites are found in the Lower Cretaceous succession in Spitsbergen. During the Early Cretaceous, Spitsbergen was at a palaeolatitude of 60°N, and was part of a shallow epicontinental sea that formed during the Mesozoic as Atlantic rifting propagated northwards. Though the Early Cretaceous was generally characterised by greenhouse climate conditions, episodic cold snaps occurred during the Valanginian (the "Weissert Event") and during Aptian-Albian. Using high resolution carbon-isotope stratigraphy, we show that the first occurrences of glendonites are in the upper Lower Hauterivian and in the very upper Upper Hauterivian, stratigraphically higher than the Valanginian cooling event. Glendonites are also found in horizons in the Upper Aptian, coincident with the Aptian-Albian cold snap. Petrological analysis of the glendonite structure reveals differences between the Hauterivian and Aptian glendonites, with evidence for multiple diagenetic phases of growth in the Hauterivian glendonites, suggesting oscillating chemical conditions. This evidence suggests that local environmental conditions may have a stronger control on glendonite formation and preservation than global climate. We present a new model for ikaite growth and slow transformation to glendonite in marine sediments, which points to a more complex suite of diagenetic transformations than previously modelled. Furthermore, we critically assess whether such pseudomorphs after marine sedimentary ikaite may be indicators

  6. Postmenopausal Osteoporosis Management: A Review of the Evidence to Inform the Development of Quality Indicators.

    PubMed

    Conklin, Annalijn; Yaqub, Ohid; Celia, Claire; Nolte, Ellen

    2012-01-01

    This article aims to inform the development of quality indicators for postmenopausal osteoporosis management through (a) assessing the evidence for screening and diagnosis of osteoporosis and related risk factors, and for prevention and treatment of osteoporosis and osteoporosis-related fractures; (b) describing current practice for managing postmenopausal osteoporosis in Europe; and (c) highlighting existing gaps in the evidence base and management practices in Europe. Analyses involved a comprehensive review of reviews regarding the screening and diagnosis of osteoporosis and related risk factors and the prevention and treatment of osteoporosis and osteoporosis-related fractures. While this identified a well-developed evidence base on the effects of selected treatments on clinical outcomes of postmenopausal osteoporosis and associated fractures, and on the usefulness of selected simple risk factor assessment tools to identify postmenopausal women who would benefit from further diagnostic assessment, uncertainties remain regarding for example the optimal use of pharmacological interventions for preventive purposes and the effectiveness of population-based screening. We also carried out case study reviews of current practices for managing postmenopausal osteoporosis in England, France, Germany and Spain. We identify a need for the establishment of routine monitoring systems to enable better understanding of contemporary patterns and trends and identify care gaps in the management of postmenopausal osteoporosis and associated fractures. Such analyses are crucial to inform targeted strategies and policies to effectively address the burden of osteoporosis and associated fractures, which is sizable and set to increase across Europe. We set out considerations as a starting point for the further development of quality measures for postmenopausal osteoporosis in Europe.

  7. Word population analysis and other evidences indicate that Shiji was amended by Liu Xiang

    NASA Astrophysics Data System (ADS)

    Chi, Ting-Ting; Wang, Shih-Chieh; Hu, Chin-Kun

    2015-11-01

    Shiji prepared by Shima Qian in Western Han Dynasty (202 BC-9 AD) was the most famous historical book in historical China. The current version of Shiji contains 130 chapters, including 10 chapters which contains some parts starting with the sentence "Mr. Chu said …"; such parts were considered to be written by Chu Shaosun by Chang Yen in the Three Kingdoms Period (220-280 AD), which was widely accepted. We have analyzed the word population in Shiji and books written by Liu Xiang (77 BC-6 BC) in Western Han Dynasty, who was a member of the royal family. Our results and other evidences indicate that the parts of Shiji starting with the sentence "Mr. Chu said …" were prepared by Liu Xiang. The other evidences include (1) The ending year of the events mentioned in "Mr. Chu said..." was considered to be 47 BC, the second year of Emperor Yuan (as Emperor in 48 BC-32 BC) of Western Han Dynasty, and in the same year Liu Xiang was put into a jail, then left power center for many years. Such coincidence suggests that Liu Xiang wrote the parts "Mr. Chu said …" in Shiji. (2) Liu Xiang's education, interest, and writings are quite consistent with the parts with "Mr. Chu said …" in Shiji. On the other hand, one cannot find such a connection with Chu Shaosun, who did not have any other identified writings for comparison.

  8. [ General postural rehabilitation in musculoskeletal diseases: scientific evidence and clinical indications].

    PubMed

    Vanti, C; Generali, A; Ferrari, S; Nava, T; Tosarelli, D; Pillastrini, P

    2007-01-01

    Several studies on the treatment of musculoskeletal diseases with physiotherapy and clinical experiences on the basis of a method called Rééducation Posturale Globale (RPG), have highlighted the usefulness of this treatment. Although such treatment technique is commonly used in physical therapy practice, only few studies support its therapeutic effectiveness. To search the literature for evidence of RPG effectiveness, in order to identify the most appropriate therapeutic contexts for its use. A review of the literature through the following databases: PubMed, Embase, Cinahl, Pedro, and Medscape. The keywords used for the search in the databases are: Rééducation Posturale Globale, Souchard, Posture, and Manual Therapy. The following clinical studies were selected: randomized controlled studies, non-randomized controlled studies, observation studies, and case reports, in English, Spanish, Portuguese, and Italian. Out of 18 studies found, 9 were analyzed: 2 randomized controlled studies, 2 non-randomized controlled studies, 3 non-controlled studies, and 2 case reports. The RPG method has been shown to be an effective treatment technique for musculoskeletal diseases, in particular for ankylosing spondylitis, acute and chronic low back pain, and lumbar discherniation. Although the scarcity of rigorous experimental trials on a large scale does not allow the drawing of undisputable conclusions, the results gathered up to now are an encouragement to carry on research in the field of conservative treatment.

  9. Competition and quality indicators in the health care sector: empirical evidence from the Dutch hospital sector.

    PubMed

    Croes, R R; Krabbe-Alkemade, Y J F M; Mikkers, M C

    2017-01-03

    There is much debate about the effect of competition in healthcare and especially the effect of competition on the quality of healthcare, although empirical evidence on this subject is mixed. The Netherlands provides an interesting case in this debate. The Dutch system could be characterized as a system involving managed competition and mandatory healthcare insurance. Information about the quality of care provided by hospitals has been publicly available since 2008. In this paper, we evaluate the relationship between quality scores for three diagnosis groups and the market power indicators of hospitals. We estimate the impact of competition on quality in an environment of liberalized pricing. For this research, we used unique price and production data relating to three diagnosis groups (cataract, adenoid and tonsils, bladder tumor) produced by Dutch hospitals in the period 2008-2011. We also used the quality indicators relating to these diagnosis groups. We reveal a negative relationship between market share and quality score for two of the three diagnosis groups studied, meaning that hospitals in competitive markets have better quality scores than those in concentrated markets. We therefore conclude that more competition is associated with higher quality scores.

  10. Neural Correlates of Indicators of Sound Change in Cantonese: Evidence from Cortical and Subcortical Processes

    PubMed Central

    Maggu, Akshay R.; Liu, Fang; Antoniou, Mark; Wong, Patrick C. M.

    2016-01-01

    Across time, languages undergo changes in phonetic, syntactic, and semantic dimensions. Social, cognitive, and cultural factors contribute to sound change, a phenomenon in which the phonetics of a language undergo changes over time. Individuals who misperceive and produce speech in a slightly divergent manner (called innovators) contribute to variability in the society, eventually leading to sound change. However, the cause of variability in these individuals is still unknown. In this study, we examined whether such misperceptions are represented in neural processes of the auditory system. We investigated behavioral, subcortical (via FFR), and cortical (via P300) manifestations of sound change processing in Cantonese, a Chinese language in which several lexical tones are merging. Across the merging categories, we observed a similar gradation of speech perception abilities in both behavior and the brain (subcortical and cortical processes). Further, we also found that behavioral evidence of tone merging correlated with subjects' encoding at the subcortical and cortical levels. These findings indicate that tone-merger categories, that are indicators of sound change in Cantonese, are represented neurophysiologically with high fidelity. Using our results, we speculate that innovators encode speech in a slightly deviant neurophysiological manner, and thus produce speech divergently that eventually spreads across the community and contributes to sound change. PMID:28066218

  11. Cosmetics for acne: indications and recommendations for an evidence-based approach.

    PubMed

    Dall'oglio, F; Tedeschi, A; Fabbrocini, G; Veraldi, S; Picardo, M; Micali, G

    2015-02-01

    The aim of this review was to evaluate, by a thorough revision of the literature, the true efficacy of currently available topic and systemic cosmetic acne agents. The efficacy of currently available cosmetic acne agents has been retrospectively evaluated via thorough revision of the literature on matched electronic databases (PubMed). All retrieved studies, either randomized clinical trials or clinical trials, controlled or uncontrolled were considered. Scientific evidence suggests that most cosmetic products for acne may enhance the clinical outcome. Cleansers should be indicated to all acne patients; those containing benzoyl peroxide or azelaic/salicylic acid/triclosan show the best efficacy profile. Sebum-controlling agents containing nicotinamide or zinc acetate may minimize excessive sebum production. Cosmetics with antimicrobial and anti-inflammatory substances such as, respectively, ethyl lactate or phytosphingosine and nicotinamide or resveratrol, may speed acne recovery. Topical corneolytics, including retinaldehyde/glycolic acid or lactic acid, induce a comedolytic effect and may also facilitate skin absorption of topical drugs. Finally, the use of specific moisturizers should be strongly recommended in all acne patients. Cosmetics, if correctly prescribed, may improve the performance of the therapy, whereas wrong procedures and/or inadequate cosmetics may worsen acne. Cosmetological recommendations may allow clinicians to make informed decisions about the role of various cosmetics and to indentify the appropriate indications and precautions. The choice of the most effective product should take into consideration the ongoing pharmacological therapy and acne type/severity as well.

  12. Indications for implantable cardioverter-defibrillators based on evidence and judgment.

    PubMed

    Myerburg, Robert J; Reddy, Vivek; Castellanos, Agustin

    2009-08-25

    Implantable cardioverter-defibrillators (ICDs) are generally reliable medical devices that have the potential to add quality years of life for appropriate candidates. Indications for ICDs have emerged from a series of randomized clinical trials, observational data from cohorts of high-risk patients with less common diseases, and expert opinion based on limited data in uncommon disorders. The randomized trials are limited by inadequate stratification designs that resulted from insufficient funding availability. The result was outcomes that led to uneven applications, based in part on post-implant experience of device utilization. In this document, we explore the basis for the features of the evidence available to support ICD use, the role of clinical judgment in circumstances in which data are limited or lacking, and the need for additional research to improve the specificity of indications. Directions for new research initiatives are considered. In addition, a general overview of a clinical research paradigm is presented, in which the research and health care delivery arms of the health care enterprise combine in research design and funding, as the latter bears the impact of the outcomes of the former. Impact estimates during the design of trials, considering reasonable contingencies for outcomes, are suggested as a means of justifying the size, scope, and appropriate costs of studies. If we who are involved in clinical research and health care delivery do not resolve this problem, for both ICDs and other new therapies that appear in the future, society will do it for us.

  13. Experimental evidence and molecular modeling of the interaction between hRSV-NS1 and quercetin.

    PubMed

    Gomes, Deriane Elias; Caruso, Ícaro Putinhon; de Araujo, Gabriela Campos; de Lourenço, Isabella Otenio; de Melo, Fernando Alves; Cornélio, Marinônio Lopes; Fossey, Marcelo Andrés; de Souza, Fátima Pereira

    2016-04-01

    Human Respiratory Syncytial Virus is one of the major causes of acute respiratory infections in children, causing bronchiolitis and pneumonia. Non-Structural Protein 1 (NS1) is involved in immune system evasion, a process that contributes to the success of hRSV replication. This protein can act by inhibiting or neutralizing several steps of interferon pathway, as well as by silencing the hRSV ribonucleoproteic complex. There is evidence that quercetin can reduce the infection and/or replication of several viruses, including RSV. The aims of this study include the expression and purification of the NS1 protein besides experimental and computational assays of the NS1-quercetin interaction. CD analysis showed that NS1 secondary structure composition is 30% alpha-helix, 21% beta-sheet, 23% turn and 26% random coils. The melting temperature obtained through DSC analysis was around 56°C. FRET analysis showed a distance of approximately 19Å between the NS1 and quercetin. Fluorescence titration results showed that the dissociation constant of the NS1-quercetin interaction was around 10(-6)M. In thermodynamic analysis, the enthalpy and entropy balanced forces indicated that the NS1-quercetin interaction presented both hydrophobic and electrostatic contributions. The computational results from the molecular modeling for NS1 structure and molecular docking regarding its interaction with quercetin corroborate the experimental data.

  14. Executive Summary of Respiratory Indications for Polysomnography in Children: An Evidence-Based Review

    PubMed Central

    Wise, Merrill S.; Nichols, Cynthia D.; Grigg-Damberger, Madeleine M.; Marcus, Carole L.; Witmans, Manisha B.; Kirk, Valerie G.; D'Andrea, Lynn A.; Hoban, Timothy F.

    2011-01-01

    Objective: This comprehensive, evidence-based review provides a systematic analysis of the literature regarding the validity, reliability, and clinical utility of polysomnography for characterizing breathing during sleep in children. Findings serve as the foundation of practice parameters regarding respiratory indications for polysomnography in children. Methods: A task force of content experts performed a systematic review of the relevant literature and graded the evidence using a standardized grading system. Two hundred forty-three evidentiary papers were reviewed, summarized, and graded. The analysis addressed the operating characteristics of polysomnography as a diagnostic procedure in children and identified strengths and limitations of polysomnography for evaluation of respiratory function during sleep. Results: The analysis documents strong face validity and content validity, moderately strong convergent validity when comparing respiratory findings with a variety of relevant independent measures, moderate-to-strong test-retest validity, and limited data supporting discriminant validity for characterizing breathing during sleep in children. The analysis documents moderate-to-strong test-retest reliability and interscorer reliability based on limited data. The data indicate particularly strong clinical utility in children with suspected sleep related breathing disorders and obesity, evolving metabolic syndrome, neurological, neurodevelopmental, or genetic disorders, and children with craniofacial syndromes. Specific consideration was given to clinical utility of polysomnography prior to adenotonsillectomy (AT) for confirmation of obstructive sleep apnea syndrome. The most relevant findings include: (1) recognition that clinical history and examination are often poor predictors of respiratory polygraphic findings, (2) preoperative polysomnography is helpful in predicting risk for perioperative complications, and (3) preoperative polysomnography is often helpful

  15. The Time of Maximum Post-Ischemic Hyperperfusion Indicates Infarct Growth Following Transient Experimental Ischemia

    PubMed Central

    Wegener, Susanne; Artmann, Judith; Luft, Andreas R.; Buxton, Richard B.; Weller, Michael; Wong, Eric C.

    2013-01-01

    After recanalization, cerebral blood flow (CBF) can increase above baseline in cerebral ischemia. However, the significance of post-ischemic hyperperfusion for tissue recovery remains unclear. To analyze the course of post-ischemic hyperperfusion and its impact on vascular function, we used magnetic resonance imaging (MRI) with pulsed arterial spin labeling (pASL) and measured CBF quantitatively during and after a 60 minute transient middle cerebral artery occlusion (MCAO) in adult rats. We added a 5% CO2 - challenge to analyze vasoreactivity in the same animals. Results from MRI were compared to histological correlates of angiogenesis. We found that CBF in the ischemic area recovered within one day and reached values significantly above contralateral thereafter. The extent of hyperperfusion changed over time, which was related to final infarct size: early (day 1) maximal hyperperfusion was associated with smaller lesions, whereas a later (day 4) maximum indicated large lesions. Furthermore, after initial vasoparalysis within the ischemic area, vasoreactivity on day 14 was above baseline in a fraction of animals, along with a higher density of blood vessels in the ischemic border zone. These data provide further evidence that late post-ischemic hyperperfusion is a sequel of ischemic damage in regions that are likely to undergo infarction. However, it is transient and its resolution coincides with re-gaining of vascular structure and function. PMID:23741488

  16. Role of experimental and epidemiological evidence of carcinogenicity in the primary prevention of cancer.

    PubMed

    Tomatis, Lorenzo

    2006-01-01

    Experimental chemical carcinogenesis, which included long-term tests in experimental animals,had a dominating role in cancer research between the 1920s and the late 1960s. Two events marked a certain decline of confidence in the ability of experimental results to predict human risks: the incapacity of developing methods to identify agents acting on the different steps of the carcinogenesis process, and the incapacity to reproduce experimentally the strong evidence of carcinogenicity of tobacco smoke provided by epidemiological studies. It was at that time that epidemiologists and biostatisticians developed criteria for assessing the causation of chronic-degenerative diseases relying primarily on epidemiological evidence. In 1969 the International Agency for Research on Cancer (IARC) did initiate a programme for identifying the cause of cancer with the aim of promoting the primary prevention of cancer. The programme is focused on the evaluation of the carcinogenicity of environmental agents on the basis of both the experimental and epidemiological evidence and, since the 1990s, a balanced use of the new tools provided by advances in toxicology, molecular biology and genetics. A strong point of the IARC programme is that in the absence of adequate human data it is reasonable and prudent to regard agents for which there is sufficient experimental evidence of carcinogenicity as if they were carcinogenic to humans.

  17. Infectivity of DWV Associated to Flower Pollen: Experimental Evidence of a Horizontal Transmission Route

    PubMed Central

    Luisi, Elena; Forzan, Mario; Giusti, Matteo; Sagona, Simona; Tolari, Francesco; Felicioli, Antonio

    2014-01-01

    Deformed wing virus (DWV) is a honeybee pathogen whose presence is generally associated with infestation of the colony by the mite Varroa destructor, leading to the onset of infections responsible for the collapse of the bee colony. DWV contaminates bee products such as royal jelly, bee-bread and honey stored within the infected hive. Outside the hive, DWV has been found in pollen loads collected directly from infected as well as uninfected forager bees. It has been shown that the introduction of virus-contaminated pollen into a DWV-free hive results in the production of virus-contaminated food, whose role in the development of infected bees from virus-free eggs has been experimentally demonstrated. The aim of this study was twofold: (i) to ascertain the presence of DWV on pollen collected directly from flowers visited by honeybees and then quantify the viral load and (ii) determine whether the virus associated with pollen is infective. The results of our investigation provide evidence that DWV is present on pollen sampled directly from visited flowers and that, following injection in individuals belonging to the pollinator species Apis mellifera, it is able to establish an active infection, as indicated by the presence of replicating virus in the head of the injected bees. We also provide the first indication that the pollinator species Osmia cornuta is susceptible to DWV infection. PMID:25419704

  18. Infectivity of DWV associated to flower pollen: experimental evidence of a horizontal transmission route.

    PubMed

    Mazzei, Maurizio; Carrozza, Maria Luisa; Luisi, Elena; Forzan, Mario; Giusti, Matteo; Sagona, Simona; Tolari, Francesco; Felicioli, Antonio

    2014-01-01

    Deformed wing virus (DWV) is a honeybee pathogen whose presence is generally associated with infestation of the colony by the mite Varroa destructor, leading to the onset of infections responsible for the collapse of the bee colony. DWV contaminates bee products such as royal jelly, bee-bread and honey stored within the infected hive. Outside the hive, DWV has been found in pollen loads collected directly from infected as well as uninfected forager bees. It has been shown that the introduction of virus-contaminated pollen into a DWV-free hive results in the production of virus-contaminated food, whose role in the development of infected bees from virus-free eggs has been experimentally demonstrated. The aim of this study was twofold: (i) to ascertain the presence of DWV on pollen collected directly from flowers visited by honeybees and then quantify the viral load and (ii) determine whether the virus associated with pollen is infective. The results of our investigation provide evidence that DWV is present on pollen sampled directly from visited flowers and that, following injection in individuals belonging to the pollinator species Apis mellifera, it is able to establish an active infection, as indicated by the presence of replicating virus in the head of the injected bees. We also provide the first indication that the pollinator species Osmia cornuta is susceptible to DWV infection.

  19. Towards evidence-based management: creating an informative database of nursing-sensitive indicators.

    PubMed

    Patrician, Patricia A; Loan, Lori; McCarthy, Mary; Brosch, Laura R; Davey, Kimberly S

    2010-12-01

    The purpose of this paper is to describe the creation, evolution, and implementation of a database of nursing-sensitive and potentially nursing-sensitive indicators, the Military Nursing Outcomes Database (MilNOD). It discusses data quality, utility, and lessons learned. Prospective data collected each shift include direct staff hours by levels (i.e., registered nurse, other licensed and unlicensed providers), staff categories (i.e., military, civilian, contract, and reservist), patient census, acuity, and admissions, discharges, and transfers. Retrospective adverse event data (falls, medication errors, and needle-stick injuries) were collected from existing records. Annual patient satisfaction, nurse work environment, and pressure ulcer and restraint prevalence surveys were conducted. The MilNOD contains shift level data from 56 units in 13 military hospitals and is used to target areas for managerial and clinical performance improvement. This methodology can be modified for use in other healthcare systems. As standard tools for evidence-based management, databases such as MilNOD allow nurse leaders to track the status of nursing and adverse events in their facilities. No claim to original US government works.

  20. Non-monotonic Temporal-Weighting Indicates a Dynamically Modulated Evidence-Integration Mechanism

    PubMed Central

    Usher, Marius

    2016-01-01

    Perceptual decisions are thought to be mediated by a mechanism of sequential sampling and integration of noisy evidence whose temporal weighting profile affects the decision quality. To examine temporal weighting, participants were presented with two brightness-fluctuating disks for 1, 2 or 3 seconds and were requested to choose the overall brighter disk at the end of each trial. By employing a signal-perturbation method, which deploys across trials a set of systematically controlled temporal dispersions of the same overall signal, we were able to quantify the participants’ temporal weighting profile. Results indicate that, for intervals of 1 or 2 sec, participants exhibit a primacy-bias. However, for longer stimuli (3-sec) the temporal weighting profile is non-monotonic, with concurrent primacy and recency, which is inconsistent with the predictions of previously suggested computational models of perceptual decision-making (drift-diffusion and Ornstein-Uhlenbeck processes). We propose a novel, dynamic variant of the leaky-competing accumulator model as a potential account for this finding, and we discuss potential neural mechanisms. PMID:26866598

  1. Forensic Geopedology and Micropedology: New Indications and Lookouts from Pigs Experimental Burials.

    NASA Astrophysics Data System (ADS)

    Ern, Stephania Irmgard Elena; Trombino, Luca

    2013-04-01

    The role played by soil scientists in the modern forensic science is very real and important, above all in the crime scenes when buried remains, both strongly decomposed or skeletal, are found. Thanks to a PhD project on Forensic Geopedology, an interdisciplinary team of the Universities of Milano and Milano Bicocca, has been working for the last four years on several sets of experimental burials of pigs and piglets, in different soil types and for different times of burial, in order to get new evidences on environmental responses to the burial, including geopedological and micropedological aspects. The present work constitutes a conclusive synthesis of results emerged from comparative soil characterizations, listed as follow: - Grainsize analyses; - Determination of pH in H2O and KCl; - Total Nitrogen and Organic Carbon analyses: - Quantification of Available Phosphorous; - Determination of Cation Exchange Capacity and Base Saturation; - Analyses of Volatile Fatty Acids; - Scanning Electron Microscope and Energy Dispersive Spectroscopy analyses; - Petrographic Optical Microscope analyses (including thin sections descriptions). It is proposed a diachronic picture of the project where it is possible to follow the variability of significance of the different kinds of analyses carried out. The achieved results, especially when cross-checked, are very stimulating as regards the setting of analytical protocols for: - The determination of time since burial (TSB); - The discrimination between primary and secondary burials; - The identification of corpses concealments. All the analyses and different approaches discussed and addressed in this work require extreme care when applied to real forensic scenarios; however, the protocols tested can be a piece of a large and articulated puzzle that depicts the major forensic case studies in which Geopedology can be of help in solving problems or in answering some peculiar questions. It is important to understand that a science so

  2. Genomic Regions Associated with Feed Efficiency Indicator Traits in an Experimental Nellore Cattle Population.

    PubMed

    Olivieri, Bianca Ferreira; Mercadante, Maria Eugênia Zerlotti; Cyrillo, Joslaine Noely Dos Santos Gonçalves; Branco, Renata Helena; Bonilha, Sarah Figueiredo Martins; de Albuquerque, Lucia Galvão; Silva, Rafael Medeiros de Oliveira; Baldi, Fernando

    2016-01-01

    The objective of this study was to identify genomic regions and metabolic pathways associated with dry matter intake, average daily gain, feed efficiency and residual feed intake in an experimental Nellore cattle population. The high-density SNP chip (Illumina High-Density Bovine BeadChip, 777k) was used to genotype the animals. The SNP markers effects and their variances were estimated using the single-step genome wide association method. The (co)variance components were estimated by Bayesian inference. The chromosome segments that are responsible for more than 1.0% of additive genetic variance were selected to explore and determine possible quantitative trait loci. The bovine genome Map Viewer was used to identify genes. In total, 51 genomic regions were identified for all analyzed traits. The heritability estimated for feed efficiency was low magnitude (0.13±0.06). For average daily gain, dry matter intake and residual feed intake, heritability was moderate to high (0.43±0.05; 0.47±0.05, 0.18±0.05, respectively). A total of 8, 17, 14 and 12 windows that are responsible for more than 1% of the additive genetic variance for dry matter intake, average daily gain, feed efficiency and residual feed intake, respectively, were identified. Candidate genes GOLIM4, RFX6, CACNG7, CACNG6, CAPN8, CAPN2, AKT2, GPRC6A, and GPR45 were associated with feed efficiency traits. It was expected that the response to selection would be higher for residual feed intake than for feed efficiency. Genomic regions harboring possible QTL for feed efficiency indicator traits were identified. Candidate genes identified are involved in energy use, metabolism protein, ion transport, transmembrane transport, the olfactory system, the immune system, secretion and cellular activity. The identification of these regions and their respective candidate genes should contribute to the formation of a genetic basis in Nellore cattle for feed efficiency indicator traits, and these results would support

  3. Genomic Regions Associated with Feed Efficiency Indicator Traits in an Experimental Nellore Cattle Population

    PubMed Central

    Olivieri, Bianca Ferreira; Mercadante, Maria Eugênia Zerlotti; Cyrillo, Joslaine Noely dos Santos Gonçalves; Branco, Renata Helena; Bonilha, Sarah Figueiredo Martins; de Albuquerque, Lucia Galvão; Silva, Rafael Medeiros de Oliveira; Baldi, Fernando

    2016-01-01

    The objective of this study was to identify genomic regions and metabolic pathways associated with dry matter intake, average daily gain, feed efficiency and residual feed intake in an experimental Nellore cattle population. The high-density SNP chip (Illumina High-Density Bovine BeadChip, 777k) was used to genotype the animals. The SNP markers effects and their variances were estimated using the single-step genome wide association method. The (co)variance components were estimated by Bayesian inference. The chromosome segments that are responsible for more than 1.0% of additive genetic variance were selected to explore and determine possible quantitative trait loci. The bovine genome Map Viewer was used to identify genes. In total, 51 genomic regions were identified for all analyzed traits. The heritability estimated for feed efficiency was low magnitude (0.13±0.06). For average daily gain, dry matter intake and residual feed intake, heritability was moderate to high (0.43±0.05; 0.47±0.05, 0.18±0.05, respectively). A total of 8, 17, 14 and 12 windows that are responsible for more than 1% of the additive genetic variance for dry matter intake, average daily gain, feed efficiency and residual feed intake, respectively, were identified. Candidate genes GOLIM4, RFX6, CACNG7, CACNG6, CAPN8, CAPN2, AKT2, GPRC6A, and GPR45 were associated with feed efficiency traits. It was expected that the response to selection would be higher for residual feed intake than for feed efficiency. Genomic regions harboring possible QTL for feed efficiency indicator traits were identified. Candidate genes identified are involved in energy use, metabolism protein, ion transport, transmembrane transport, the olfactory system, the immune system, secretion and cellular activity. The identification of these regions and their respective candidate genes should contribute to the formation of a genetic basis in Nellore cattle for feed efficiency indicator traits, and these results would support

  4. Developmental origins of health and disease: experimental and human evidence of fetal programming for metabolic syndrome.

    PubMed

    de Gusmão Correia, M L; Volpato, A M; Águila, M B; Mandarim-de-Lacerda, C A

    2012-07-01

    The concept of developmental origins of health and disease has been defined as the process through which the environment encountered before birth, or in infancy, shapes the long-term control of tissue physiology and homeostasis. The evidence for programming derives from a large number of experimental and epidemiological observations. Several nutritional interventions during diverse phases of pregnancy and lactation in rodents are associated with fetal and neonatal programming for metabolic syndrome. In this paper, recent experimental models and human epidemiological studies providing evidence for the fetal programming associated with the development of metabolic syndrome and related diseases are revisited.

  5. Development of an epiphyte indicator of nutrient enrichment. A critical evaluation of observational and experimental studies

    EPA Science Inventory

    An extensive review of the literature on epiphytes on submerged aquatic vegetation (SAV), primarily seagrasses but including some brackish and freshwater rooted macrophytes, was conducted in order to evaluate the evidence for response of epiphyte metrics to increased nutrients. ...

  6. First experimental evidence for the presence of a CRISPR toxin in sulfolobus.

    PubMed

    He, Fei; Chen, Lanming; Peng, Xu

    2014-11-11

    Clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated (cas) genes constitute the adaptive immune system in bacteria and archaea. Although the CRISPR-Cas systems have been hypothesized to encode potential toxins, no experimental data supporting the hypothesis are available in the literature. In this work, we provide the first experimental evidence for the presence of a toxin gene in the type I-A CRISPR system of hyperthermophilic archaeon Sulfolobus. csa5, under the control of its native promoter in a shuttle vector, could not be transformed into CRISPR-deficient mutant Sulfolobus solfataricus Sens1, demonstrating a strong toxicity in the cells. A single-amino-acid mutation destroying the intersubunit bridge of Csa5 attenuated the toxicity, indicative of the importance of Csa5 oligomerization for its toxicity. In line with the absence of Csa5 toxicity in S. solfataricus InF1 containing functional CRISPR systems, the expression of csa5 is repressed in InF1 cells. Induced from the arabinose promoter in Sens1 cells, Csa5 oligomers resistant to 1% SDS co-occur with chromosome degradation and cell death, reinforcing the connection between Csa5 oligomerization and its toxicity. Importantly, a rudivirus was shown to induce Csa5 expression and the formation of SDS-resistant Csa5 oligomers in Sulfolobus cells. This demonstrates that the derepression of csa5 and the subsequent Csa5 oligomerization take place in native virus-host systems. Thus, csa5 is likely to act as a suicide gene under certain circumstances to inhibit virus spreading.

  7. Photorespiratory Bypasses Lead to Increased Growth in Arabidopsis thaliana: Are Predictions Consistent with Experimental Evidence?

    PubMed Central

    Basler, Georg; Küken, Anika; Fernie, Alisdair R.; Nikoloski, Zoran

    2016-01-01

    Arguably, the biggest challenge of modern plant systems biology lies in predicting the performance of plant species, and crops in particular, upon different intracellular and external perturbations. Recently, an increased growth of Arabidopsis thaliana plants was achieved by introducing two different photorespiratory bypasses via metabolic engineering. Here, we investigate the extent to which these findings match the predictions from constraint-based modeling. To determine the effect of the employed metabolic network model on the predictions, we perform a comparative analysis involving three state-of-the-art metabolic reconstructions of A. thaliana. In addition, we investigate three scenarios with respect to experimental findings on the ratios of the carboxylation and oxygenation reactions of Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). We demonstrate that the condition-dependent growth phenotypes of one of the engineered bypasses can be qualitatively reproduced by each reconstruction, particularly upon considering the additional constraints with respect to the ratio of fluxes for the RuBisCO reactions. Moreover, our results lend support for the hypothesis of a reduced photorespiration in the engineered plants, and indicate that specific changes in CO2 exchange as well as in the proxies for co-factor turnover are associated with the predicted growth increase in the engineered plants. We discuss our findings with respect to the structure of the used models, the modeling approaches taken, and the available experimental evidence. Our study sets the ground for investigating other strategies for increase of plant biomass by insertion of synthetic reactions. PMID:27092301

  8. Study types and reliability of Real World Evidence compared with experimental evidence used in Polish reimbursement decision-making processes.

    PubMed

    Wilk, N; Wierzbicka, N; Skrzekowska-Baran, I; Moćko, P; Tomassy, J; Kloc, K

    2017-04-01

    The aim of this study was to identify the relationship and impact between Real World Evidence (RWE) and experimental evidence (EE) in Polish decision-making processes for the drugs from selected Anatomical Therapeutic Chemical (ATC) groups. Descriptive study. A detailed analysis was performed for 58 processes from five ATC code groups in which RWE for effectiveness, or effectiveness and safety were cited in Agency for Health Technology Assessment and Tariff System's (AOTMiT) documents published between January 2012 and September 2015: Verification Analysis of AOTMiT, Statement of the Transparency Council of AOTMiT, and Recommendation of the President of AOTMiT. In 62% of the cases, RWE supported the EE and confirmed its main conclusions. The majority of studies in the EE group showed to be RCTs (97%), and the RWE group included mainly cohort studies (89%). There were more studies without a control group within RWE compared with the EE group (10% vs 1%). Our results showed that EE are more often assessed using Jadad, NICE or NOS scale by AOTMiT compared with RWE (93% vs 48%). When the best evidence within a given decision-making process is analysed, half of RWE and two-thirds of EE are considered high quality evidence. RWE plays an important role in the decision-making processes on public funding of drugs in Poland, contributing to nearly half (45%) of all the evidence considered. There exist such processes in which the proportion of RWE is dominant, with one process showing RWE as the only evidence presented. Copyright © 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

  9. Susceptibility-weighted imaging in the experimental autoimmune encephalomyelitis model of multiple sclerosis indicates elevated deoxyhemoglobin, iron deposition and demyelination.

    PubMed

    Nathoo, Nabeela; Agrawal, Smriti; Wu, Ying; Haylock-Jacobs, Sarah; Yong, V Wee; Foniok, Tad; Barnes, Samuel; Obenaus, Andre; Dunn, Jeff F

    2013-05-01

    Susceptibility-weighted imaging (SWI) is an iron-sensitive magnetic resonance imaging (MRI) method that has shown iron-related lesions in multiple sclerosis (MS) patients. The contribution of deoxyhemoglobin to the signals seen in SWI has not been well characterized in MS. To determine if SWI lesions (seen as focal hypointensities) exist in the experimental autoimmune encephalomyelitis (EAE) animal model of MS, and to determine whether the lesions relate to iron deposits, inflammation, demyelination, and/or deoxyhemoglobin in the vasculature. We performed SWI on the lumbar spinal cord and cerebellum of EAE and control mice (both complete Freund's adjuvant/pertussis toxin (CFA/PTX)-immunized and naive). We also performed SWI on mice before and after perfusion (to remove blood from vessels). SWI lesions were counted and their locations were compared to histology for iron, myelin and inflammation. SWI lesions were found to exist in the EAE model. Many lesions seen by SWI were not present after perfusion, especially at the grey/white matter boundary of the lumbar spinal cord and in the cerebellum, indicating that these lesion signals were associated with deoxyhemoglobin present in the lumen of vessels. We also observed SWI lesions in the white matter of the lumbar spinal cord that corresponded to iron deposition, inflammation and demyelination. In the cerebellum, SWI lesions were present in white matter tracts, where we found histological evidence of inflammatory perivascular cuffs. SWI lesions exist in EAE mice. Many lesions seen in SWI were a result of deoxyhemoglobin in the blood, and so may indicate areas of hypoxia. A smaller number of SWI lesions coincided with parenchymal iron, demyelination, and/or inflammation.

  10. Experimental evidence for synchronization to a musical beat in a nonhuman animal.

    PubMed

    Patel, Aniruddh D; Iversen, John R; Bregman, Micah R; Schulz, Irena

    2009-05-26

    The tendency to move in rhythmic synchrony with a musical beat (e.g., via head bobbing, foot tapping, or dance) is a human universal [1] yet is not commonly observed in other species [2]. Does this ability reflect a brain specialization for music cognition, or does it build on neural circuitry that ordinarily serves other functions? According to the "vocal learning and rhythmic synchronization" hypothesis [3], entrainment to a musical beat relies on the neural circuitry for complex vocal learning, an ability that requires a tight link between auditory and motor circuits in the brain [4, 5]. This hypothesis predicts that only vocal learning species (such as humans and some birds, cetaceans, and pinnipeds, but not nonhuman primates) are capable of synchronizing movements to a musical beat. Here we report experimental evidence for synchronization to a beat in a sulphur-crested cockatoo (Cacatua galerita eleonora). By manipulating the tempo of a musical excerpt across a wide range, we show that the animal spontaneously adjusts the tempo of its rhythmic movements to stay synchronized with the beat. These findings indicate that synchronization to a musical beat is not uniquely human and suggest that animal models can provide insights into the neurobiology and evolution of human music [6].

  11. Experimental evidence of massive-scale emotional contagion through social networks.

    PubMed

    Kramer, Adam D I; Guillory, Jamie E; Hancock, Jeffrey T

    2014-06-17

    Emotional states can be transferred to others via emotional contagion, leading people to experience the same emotions without their awareness. Emotional contagion is well established in laboratory experiments, with people transferring positive and negative emotions to others. Data from a large real-world social network, collected over a 20-y period suggests that longer-lasting moods (e.g., depression, happiness) can be transferred through networks [Fowler JH, Christakis NA (2008) BMJ 337:a2338], although the results are controversial. In an experiment with people who use Facebook, we test whether emotional contagion occurs outside of in-person interaction between individuals by reducing the amount of emotional content in the News Feed. When positive expressions were reduced, people produced fewer positive posts and more negative posts; when negative expressions were reduced, the opposite pattern occurred. These results indicate that emotions expressed by others on Facebook influence our own emotions, constituting experimental evidence for massive-scale contagion via social networks. This work also suggests that, in contrast to prevailing assumptions, in-person interaction and nonverbal cues are not strictly necessary for emotional contagion, and that the observation of others' positive experiences constitutes a positive experience for people.

  12. Experimental evidence for the formation of liquid saline water on Mars

    PubMed Central

    Fischer, Erik; Martínez, Germán M; Elliott, Harvey M; Rennó, Nilton O

    2014-01-01

    Evidence for deliquescence of perchlorate salts has been discovered in the Martian polar region while possible brine flows have been observed in the equatorial region. This appears to contradict the idea that bulk deliquescence is too slow to occur during the short periods of the Martian diurnal cycle during which conditions are favorable for it. We conduct laboratory experiments to study the formation of liquid brines at Mars environmental conditions. We find that when water vapor is the only source of water, bulk deliquescence of perchlorates is not rapid enough to occur during the short periods of the day during which the temperature is above the salts' eutectic value, and the humidity is above the salts' deliquescence value. However, when the salts are in contact with water ice, liquid brine forms in minutes, indicating that aqueous solutions could form temporarily where salts and ice coexist on the Martian surface and in the shallow subsurface. Key Points The formation of brines at Martian conditions was studied experimentally Bulk deliquescence from water vapor is too slow to occur diurnally on Mars Brines form in minutes when salts are placed in direct contact with ice PMID:25821267

  13. Experimental evidence of massive-scale emotional contagion through social networks

    PubMed Central

    Kramer, Adam D. I.; Guillory, Jamie E.; Hancock, Jeffrey T.

    2014-01-01

    Emotional states can be transferred to others via emotional contagion, leading people to experience the same emotions without their awareness. Emotional contagion is well established in laboratory experiments, with people transferring positive and negative emotions to others. Data from a large real-world social network, collected over a 20-y period suggests that longer-lasting moods (e.g., depression, happiness) can be transferred through networks [Fowler JH, Christakis NA (2008) BMJ 337:a2338], although the results are controversial. In an experiment with people who use Facebook, we test whether emotional contagion occurs outside of in-person interaction between individuals by reducing the amount of emotional content in the News Feed. When positive expressions were reduced, people produced fewer positive posts and more negative posts; when negative expressions were reduced, the opposite pattern occurred. These results indicate that emotions expressed by others on Facebook influence our own emotions, constituting experimental evidence for massive-scale contagion via social networks. This work also suggests that, in contrast to prevailing assumptions, in-person interaction and nonverbal cues are not strictly necessary for emotional contagion, and that the observation of others’ positive experiences constitutes a positive experience for people. PMID:24889601

  14. Smectite clays in Mars soil - Evidence for their presence and role in Viking biology experimental results

    NASA Technical Reports Server (NTRS)

    Banin, A.; Rishpon, J.

    1979-01-01

    Evidence for the presence of smectite clays in Martian soils is reviewed and results of experiments with certain active clays simulating the Viking biology experiments are reported. Analyses of Martian soil composition by means of X-ray fluorescence spectrometry and dust storm spectroscopy and Martian geological history strongly suggest the presence of a mixture of weathered ferro-silicate minerals, mainly nontronite and montmorillonite, accompanied by soluble sulphate salts, as major constituents. Samples of montmorillonite and nontronite incubated with (C-14)-formate or the radioactive nutrient medium solution used in the Viking Labeled Release experiment, were found to produce patterns of release of radioactive gas very similar to those observed in the Viking experiments, indicating the iron-catalyzed decomposition of formate as the reaction responsible for the Viking results. The experimental results of Hubbard (1979) simulating the results of the Viking Pyrolytic Release experiment using iron montmorillonites are pointed out, and it is concluded that many of the results of the Viking biology experiments can be explained in terms of the surface activity of smectite clays in catalysis and adsorption.

  15. Kaon properties in dense nuclear matter: are there experimental evidences of in medio effects?

    NASA Astrophysics Data System (ADS)

    Mangiarotti, A.

    2009-06-01

    Beyond the general interest for nuclear matter theory, the K- in medio mass modification could have important astrophysical consequences. Experimental evidences of how a nuclear medium affects K+ and K- properties will be summarised. To reach a firm conclusion about the K-, the missing information on the flow will be shown to be still relevant.

  16. The Development of Experimentation and Evidence Evaluation Skills at Preschool Age

    ERIC Educational Resources Information Center

    Piekny, Jeanette; Grube, Dietmar; Maehler, Claudia

    2014-01-01

    Researchers taking a domain-general approach to the development of scientific reasoning long thought that the ability to engage in scientific reasoning did not develop until adolescence. However, more recent studies have shown that preschool children already have a basic ability to evaluate evidence and a basic understanding of experimentation.…

  17. Teacher Incentives in Developing Countries: Experimental Evidence from India. Research Brief

    ERIC Educational Resources Information Center

    National Center on Performance Incentives, 2008

    2008-01-01

    In "Teacher Incentives in Developing Countries: Experimental Evidence from India"--a paper presented at the National Center on Performance Incentives research to policy conference in February--Karthik Muralidharan (Harvard University) and Venkatesh Sundararaman (The World Bank) present findings from a randomized experiment conducted in…

  18. Teacher Incentives in Developing Countries: Experimental Evidence from India. Research Brief

    ERIC Educational Resources Information Center

    National Center on Performance Incentives, 2008

    2008-01-01

    In "Teacher Incentives in Developing Countries: Experimental Evidence from India"--a paper presented at the National Center on Performance Incentives research to policy conference in February--Karthik Muralidharan (Harvard University) and Venkatesh Sundararaman (The World Bank) present findings from a randomized experiment conducted in…

  19. Experimental evidence of the decrease of kinetic energy of hadrons in passing through atomic nuclei

    NASA Technical Reports Server (NTRS)

    Strugalski, Z.

    1985-01-01

    Hadrons with kinetic energies higher than the pion production threshold lose their kinetic energies monotonically in traversing atomic nuclei, due to the strong interactions in nuclear matter. This phenomenon is a crude analogy to the energy loss of charged particles in their passage through materials. Experimental evidence is presented.

  20. The Development of Experimentation and Evidence Evaluation Skills at Preschool Age

    ERIC Educational Resources Information Center

    Piekny, Jeanette; Grube, Dietmar; Maehler, Claudia

    2014-01-01

    Researchers taking a domain-general approach to the development of scientific reasoning long thought that the ability to engage in scientific reasoning did not develop until adolescence. However, more recent studies have shown that preschool children already have a basic ability to evaluate evidence and a basic understanding of experimentation.…

  1. An experimental investigation of compressor stall using an on-line distortion indicator and signal conditioner

    NASA Technical Reports Server (NTRS)

    Costakis, W. G.; Wenzel, L. M.

    1975-01-01

    The relation of the steady-state and dynamic distortions and the stall margin of a J85-13 turbojet engine was investigated. A distortion indicator capable of computing two distortion indices was used. A special purpose signal conditioner was also used as an interface between transducer signals and distortion indicator. A good correlation of steady-state distortion and stall margin was established. The prediction of stall by using the indices as instantaneous distortion indicators was not successful. A sensitivity factor that related the loss of stall margin to the turbulence level was found.

  2. Role of Oxidative Stress in Refractory Epilepsy: Evidence in Patients and Experimental Models

    PubMed Central

    Cardenas-Rodriguez, Noemi; Huerta-Gertrudis, Bernardino; Rivera-Espinosa, Liliana; Montesinos-Correa, Hortencia; Bandala, Cindy; Carmona-Aparicio, Liliana; Coballase-Urrutia, Elvia

    2013-01-01

    Oxidative stress, a state of imbalance in the production of reactive oxygen species and nitrogen, is induced by a wide variety of factors. This biochemical state is associated with systemic diseases, and diseases affecting the central nervous system. Epilepsy is a chronic neurological disorder with refractoriness to drug therapy at about 30%. Currently, experimental evidence supports the involvement of oxidative stress in seizures, in the process of their generation, and in the mechanisms associated with refractoriness to drug therapy. Hence, the aim of this review is to present information in order to facilitate the handling of this evidence and determine the therapeutic impact of the biochemical status for this pathology. PMID:23344052

  3. Relevance of the glutathione system in temporal lobe epilepsy: evidence in human and experimental models.

    PubMed

    Cárdenas-Rodríguez, Noemí; Coballase-Urrutia, Elvia; Pérez-Cruz, Claudia; Montesinos-Correa, Hortencia; Rivera-Espinosa, Liliana; Sampieri, Aristides; Carmona-Aparicio, Liliana

    2014-01-01

    Oxidative stress, which is a state of imbalance in the production of reactive oxygen species and nitrogen, is induced by a wide variety of factors. This biochemical state is associated with diseases that are systemic as well as diseases that affect the central nervous system. Epilepsy is a chronic neurological disorder, and temporal lobe epilepsy represents an estimated 40% of all epilepsy cases. Currently, evidence from human and experimental models supports the involvement of oxidative stress during seizures and in the epileptogenesis process. Hence, the aim of this review was to provide information that facilitates the processing of this evidence and investigate the therapeutic impact of the biochemical status for this specific pathology.

  4. Role of oxidative stress in refractory epilepsy: evidence in patients and experimental models.

    PubMed

    Cardenas-Rodriguez, Noemi; Huerta-Gertrudis, Bernardino; Rivera-Espinosa, Liliana; Montesinos-Correa, Hortencia; Bandala, Cindy; Carmona-Aparicio, Liliana; Coballase-Urrutia, Elvia

    2013-01-14

    Oxidative stress, a state of imbalance in the production of reactive oxygen species and nitrogen, is induced by a wide variety of factors. This biochemical state is associated with systemic diseases, and diseases affecting the central nervous system. Epilepsy is a chronic neurological disorder with refractoriness to drug therapy at about 30%. Currently, experimental evidence supports the involvement of oxidative stress in seizures, in the process of their generation, and in the mechanisms associated with refractoriness to drug therapy. Hence, the aim of this review is to present information in order to facilitate the handling of this evidence and determine the therapeutic impact of the biochemical status for this pathology.

  5. Island of Rare Earth Nuclei with Tetrahedral and Octahedral Symmetries: Possible Experimental Evidence

    SciTech Connect

    Dudek, J.; Dubray, N.; Pangon, V.; Dobaczewski, J.; Olbratowski, P.; Schunck, N.

    2006-08-18

    Calculations using realistic mean-field methods suggest the existence of nuclear shapes with tetrahedral T{sub d} and/or octahedral O{sub h} symmetries sometimes at only a few hundreds of keV above the ground states in some rare earth nuclei around {sup 156}Gd and {sup 160}Yb. The underlying single-particle spectra manifest exotic fourfold rather than Kramers's twofold degeneracies. The associated shell gaps are very strong, leading to a new form of shape coexistence in many rare earth nuclei. We present possible experimental evidence of the new symmetries based on the published experimental results--although an unambiguous confirmation will require dedicated experiments.

  6. Experimental Evidence of the Origin of Nanophase Separation in Low Hole-Doped Colossal Magnetoresistant Manganites.

    PubMed

    Cortés-Gil, Raquel; Ruiz-González, M Luisa; González-Merchante, Daniel; Alonso, José M; Hernando, Antonio; Trasobares, Susana; Vallet-Regí, María; Rojo, Juan M; González-Calbet, José M

    2016-01-13

    While being key to understanding their intriguing physical properties, the origin of nanophase separation in manganites and other strongly correlated materials is still unclear. Here, experimental evidence is offered for the origin of the controverted phase separation mechanism in the representative La1-xCaxMnO3 system. For low hole densities, direct evidence of Mn(4+) holes localization around Ca(2+) ions is experimentally provided by means of aberration-corrected scanning transmission electron microscopy combined with electron energy loss spectroscopy. These localized holes give rise to the segregated nanoclusters, within which double exchange hopping between Mn(3+) and Mn(4+) remains restricted, accounting for the insulating character of perovskites with low hole density. This localization is explained in terms of a simple model in which Mn(4+) holes are bound to substitutional divalent Ca(2+) ions.

  7. Evidence-based nursing-sensitive indicators for patients hospitalized with depression in Thailand.

    PubMed

    Thapinta, Darawan; Anders, Robert L; Mahatnirunkul, Suwat; Srikosai, Soontaree

    2010-12-01

    The aim of this study was to develop and validate nursing-sensitive indicators for patients hospitalized with depression in Thailand. The initial draft, consisting of 12 categories with 37 subcategories, was then evaluated by experts in the US and Thailand. Hospital records were then utilized to evaluate the feasibility and efficacy of the indicators. The finalized instrument consisted of 11 categories with 43 items with a validity of .98 and internal consistency of .88. This is the first set of indicators developed to evaluate nursing-sensitivity for patients hospitalized with a diagnosis of depression in Thailand. Having nursing indicators for depressed patients provides nurses with concrete tools to evaluate their work with depressed patients, allowing these staff to assess their work in a very specific, methodical, and consistent manner. When problems are discovered, both the staff and administration can work to address these issues through training, procedural changes, and departmental shifts.

  8. Experimental evidence that RNA recombination occurs in the Japanese encephalitis virus

    SciTech Connect

    Chuang, C.-K.; Chen, W.-J.

    2009-11-25

    Due to the lack of a proofreading function and error-repairing ability of genomic RNA, accumulated mutations are known to be a force driving viral evolution in the genus Flavivirus, including the Japanese encephalitis (JE) virus. Based on sequencing data, RNA recombination was recently postulated to be another factor associated with genomic variations in these viruses. We herein provide experimental evidence to demonstrate the occurrence of RNA recombination in the JE virus using two local pure clones (T1P1-S1 and CJN-S1) respectively derived from the local strains, T1P1 and CJN. Based on results from a restriction fragment length polymorphism (RFLP) assay on the C/preM junction comprising a fragment of 868 nucleotides (nt 10-877), the recombinant progeny virus was primarily formed in BHK-21 cells that had been co-infected with the two clones used in this study. Nine of 20 recombinant forms of the JE virus had a crossover in the nt 123-323 region. Sequencing data derived from these recombinants revealed that no nucleotide deletion or insertion occurred in this region favoring crossovers, indicating that precisely, not aberrantly, homologous recombination was involved. With site-directed mutagenesis, three stem-loop secondary structures were destabilized and re-stabilized in sequence, leading to changes in the frequency of recombination. This suggests that the conformation, not the free energy, of the secondary structure is important in modulating RNA recombination of the virus. It was concluded that because RNA recombination generates genetic diversity in the JE virus, this must be considered particularly in studies of viral evolution, epidemiology, and possible vaccine safety.

  9. Experimental evidence of using a circularly polarized electric field to control spiral turbulence

    NASA Astrophysics Data System (ADS)

    Ji, Lin; Zhou, Yi; Li, Qian; Qiao, Chun; Ouyang, Qi

    2013-10-01

    Experimental evidence of the use of a circularly polarized electric field to control the spiral turbulence in a reaction-diffusion system is presented. The spiral turbulence obtained in the Belousov-Zhabotinsky reaction is shown to be forced into ordered stable spiral waves or “targetlike” waves by a circularly polarized electric field with appropriate frequency and intensity. An Arnold's-tongue-shaped control phase diagram is obtained, illustrating the resonance essence of the control.

  10. Optical gain in Si/SiO2 lattice: Experimental evidence with nanosecond pulses

    NASA Astrophysics Data System (ADS)

    Khriachtchev, Leonid; Räsänen, Markku; Novikov, Sergei; Sinkkonen, Juha

    2001-08-01

    Experimental evidence of population inversion and amplified spontaneous emission was found for Si nanocrystallites embedded in SiO2 surrounding under pumping with 5 ns light pulses at 380, 400, and 500 nm. As an important property, our experiments show a short lifetime of the population inversion allowing a generation of short (a few nanosecond) amplified light pulses in the Si/SiO2 lattice. The estimate for optical gain in the present samples is 6 cm-1 at 720 nm.

  11. Experimental Evidence of Localized Oscillations in the Photosensitive Chlorine Dioxide-Iodine-Malonic Acid Reaction

    NASA Astrophysics Data System (ADS)

    Míguez, David G.; Alonso, Sergio; Muñuzuri, Alberto P.; Sagués, Francesc

    2006-10-01

    The interaction between Hopf and Turing modes has been the subject of active research in recent years. We present here experimental evidence of the existence of mixed Turing-Hopf modes in a two-dimensional system. Using the photosensitive chlorine dioxide-iodine-malonic acid reaction (CDIMA) and external constant background illumination as a control parameter, standing spots oscillating in amplitude and with hexagonal ordering were observed. Numerical simulations in the Lengyel-Epstein model for the CDIMA reaction confirmed the results.

  12. Experimental and theoretical indications for an intermediate {sigma}-dressed dibaryon in the NN interaction

    SciTech Connect

    Kukulin, V.I.; Grabmayr, P.; Faessler, A.; Abraamyan, Kh.U.; Bashkanov, M.; Clement, H.; Skorodko, T.; Pomerantsev, V.N.

    2010-06-15

    Numerous theoretical and experimental arguments in favor of the generation of intermediate {sigma}-dressed dibaryon in NN interaction at middle and short distances are presented. We argue that this intermediate dibaryon should be responsible for the strong middle-range attraction and the short-range repulsion in the NN interaction, and also for the short-range correlations in nuclei. The suggested mechanism for the {sigma}-dressing of the dibaryon is identical to that which explains the Roper-resonance structure, its dominant decay mode and its extraordinary low mass. It is arguing that the (partial) chiral symmetry restoration effects, common for the Roper resonance and dressed dibaryon, are responsible for strong renormalizing of their masses and widths and the observed {sigma}-meson mass and decay width as well. The new experimental data on 2{pi}-production in the scalar-isoscalar channel produced in pn- and pd-collisions and recent data on {gamma}{gamma} correlations in pC and dC scattering in the GeV region seems to corroborate the existence of the {sigma}-dressed dibaryon in two- and three-nucleon interactions. A similar transformation mechanism from the glue to the scalar field can be valid also in some J/{Psi} decays and in enormous {sigma}-meson production in central pp collisions at high energies.

  13. Ultra-deep Subduction of Continental Crust: Evidence from Natural Rocks and Experimental Investigations

    NASA Astrophysics Data System (ADS)

    Dobrzhinetskaya, L.; Green, H. W.

    2005-12-01

    Much of what we know about the deep subduction of continental crust is gained from study of the mineralogy of ultrahigh-pressure metamorphic (UHPM) rocks incorporated within continent-continent collision belts. UHPM rocks of metasedimentary origin were only recently recognized due to discovery of coesite, diamond, titanite inferred to have contained six-fold coordinated Si before exsolution of coesite, and TiO2 with alpha-PbO2 structure. Modern seismic tomography provides remarkable images that suggest lithospheric plates are subducted to the core-mantle boundary and may remain there stagnated during long geological times; the presence of continental material within such plates cannot be excluded. The mineral phase transformations possible within deeply subducted continental crust have been the subject of intensive laboratory experimentation during the last decade. Though many new UHP minerals were synthesized at P~ 6 to >20 GPa (e.g., wadeite, topaz-OH, phase Egg, K- and Na-hollandite) in the KNASH, KASH and ASH chemical systems, none except topaz-OH has yet been identified in UHPM rocks. The microstructural evidence of former majoritic garnet decompression is proven only for garnet peridotite, whereas no evidence of such structures has been reported yet from diamondiferous felsic rocks. It is not clear if this is because the UHPM minerals of felsic rocks are easily lost during retrograde metamorphism, or if this is because garnets crystallized in the felsic systems do not contain a large majoritic component at high pressures. There is no clear indication of what portion of subducted continental crust is returned back to Earth's surface, and what fraction may have become more dense than mantle rocks and sunk down to the mantle transition zone and even deeper. Is there any connection between mantle plumes and deeply subducted continental rocks? The UHPM discipline would also benefit from new experiments designed to reproduce decompression structures of UHP minerals

  14. Evaluation of drought indices via 1 remotely sensed data with hydrological variables: Little river experimental watershed, Georgia U.S.

    USDA-ARS?s Scientific Manuscript database

    An intercomparison among standard and remotely sensed drought indices was conducted using streamflow and soil moisture measurements collected in the Little River experimental watershed, Georgia US, during the period from 2000 to 2008. The remotely sensed Evaporative Stress Index (ESI) was identified...

  15. The Development of Experimentation and Evidence Evaluation Skills at Preschool Age

    NASA Astrophysics Data System (ADS)

    Piekny, Jeanette; Grube, Dietmar; Maehler, Claudia

    2014-01-01

    Researchers taking a domain-general approach to the development of scientific reasoning long thought that the ability to engage in scientific reasoning did not develop until adolescence. However, more recent studies have shown that preschool children already have a basic ability to evaluate evidence and a basic understanding of experimentation. Data providing insights into when exactly in the preschool years significant gains in these abilities occur are scarce. Drawing on a sample of 138 preschool children, this longitudinal study therefore examined how children's ability to evaluate evidence and their understanding of experimentation develop between the ages of four and six. Findings showed that the ability to evaluate evidence was already well developed at age four and increased steadily and significantly over time as long as the pattern of covariation was perfect. In the case of imperfect covariation, the proportion of correct answers was low over the period of observation, but showed a significant increase between the ages of four and five. If the data did not allow relationship between variables to be inferred, the proportion of correct answers was low, with a significant increase between the ages of five and six. The children's understanding of experimentation increased significantly between the ages of five and six. The implications of these findings for age-appropriate science programs in preschool are discussed.

  16. Experimental evidence for inherent Lévy search behaviour in foraging animals

    PubMed Central

    Kölzsch, Andrea; Alzate, Adriana; Bartumeus, Frederic; de Jager, Monique; Weerman, Ellen J.; Hengeveld, Geerten M.; Naguib, Marc; Nolet, Bart A.; van de Koppel, Johan

    2015-01-01

    Recently, Lévy walks have been put forward as a new paradigm for animal search and many cases have been made for its presence in nature. However, it remains debated whether Lévy walks are an inherent behavioural strategy or emerge from the animal reacting to its habitat. Here, we demonstrate signatures of Lévy behaviour in the search movement of mud snails (Hydrobia ulvae) based on a novel, direct assessment of movement properties in an experimental set-up using different food distributions. Our experimental data uncovered clusters of small movement steps alternating with long moves independent of food encounter and landscape complexity. Moreover, size distributions of these clusters followed truncated power laws. These two findings are characteristic signatures of mechanisms underlying inherent Lévy-like movement. Thus, our study provides clear experimental evidence that such multi-scale movement is an inherent behaviour rather than resulting from the animal interacting with its environment. PMID:25904671

  17. Experimental evidence for inherent Lévy search behaviour in foraging animals.

    PubMed

    Kölzsch, Andrea; Alzate, Adriana; Bartumeus, Frederic; de Jager, Monique; Weerman, Ellen J; Hengeveld, Geerten M; Naguib, Marc; Nolet, Bart A; van de Koppel, Johan

    2015-05-22

    Recently, Lévy walks have been put forward as a new paradigm for animal search and many cases have been made for its presence in nature. However, it remains debated whether Lévy walks are an inherent behavioural strategy or emerge from the animal reacting to its habitat. Here, we demonstrate signatures of Lévy behaviour in the search movement of mud snails (Hydrobia ulvae) based on a novel, direct assessment of movement properties in an experimental set-up using different food distributions. Our experimental data uncovered clusters of small movement steps alternating with long moves independent of food encounter and landscape complexity. Moreover, size distributions of these clusters followed truncated power laws. These two findings are characteristic signatures of mechanisms underlying inherent Lévy-like movement. Thus, our study provides clear experimental evidence that such multi-scale movement is an inherent behaviour rather than resulting from the animal interacting with its environment.

  18. Searching for evidence of changes in extreme rainfall indices in the Central Rift Valley of Ethiopia

    NASA Astrophysics Data System (ADS)

    Muluneh, Alemayehu; Bewket, Woldeamlak; Keesstra, Saskia; Stroosnijder, Leo

    2017-05-01

    Extreme rainfall events have serious implications for economic sectors with a close link to climate such as agriculture and food security. This holds true in the Central Rift Valley (CRV) of Ethiopia where communities rely on highly climate-sensitive rainfed subsistence farming for livelihoods. This study investigates changes in ten extreme rainfall indices over a period of 40 years (1970-2009) using 14 meteorological stations located in the CRV. The CRV consists of three landscape units: the valley floor, the escarpments, and the highlands all of which are considered in our data analysis. The Belg (March-May) and Kiremt (June-September) seasons are also considered in the analysis. The Mann-Kendall test was used to detect trends of the rainfall indices. The results indicated that at the annual time scale, more than half (57 %) of the stations showed significant trends in total wet-day precipitation (PRCPTOT) and heavy precipitation days (R10mm). Only 7-35 % of stations showed significant trends, for the other rainfall indices. Spatially, the valley floor received increasing annual rainfall while the escarpments and the highlands received decreasing annual rainfall over the last 40 years. During Belg, 50 % of the stations showed significant increases in the maximum number of consecutive dry days (CDD) in all parts of the CRV. However, most other rainfall indices during Belg showed no significant changes. During Kiremt, considering both significant and non-significant trends, almost all rainfall indices showed an increasing trend in the valley floor and a decreasing trend in the escarpment and highlands. During Belg and Kiremt, the CDD generally showed increasing tendency in the CRV.

  19. Searching for evidence of changes in extreme rainfall indices in the Central Rift Valley of Ethiopia

    NASA Astrophysics Data System (ADS)

    Muluneh, Alemayehu; Bewket, Woldeamlak; Keesstra, Saskia; Stroosnijder, Leo

    2016-02-01

    Extreme rainfall events have serious implications for economic sectors with a close link to climate such as agriculture and food security. This holds true in the Central Rift Valley (CRV) of Ethiopia where communities rely on highly climate-sensitive rainfed subsistence farming for livelihoods. This study investigates changes in ten extreme rainfall indices over a period of 40 years (1970-2009) using 14 meteorological stations located in the CRV. The CRV consists of three landscape units: the valley floor, the escarpments, and the highlands all of which are considered in our data analysis. The Belg (March-May) and Kiremt (June-September) seasons are also considered in the analysis. The Mann-Kendall test was used to detect trends of the rainfall indices. The results indicated that at the annual time scale, more than half (57 %) of the stations showed significant trends in total wet-day precipitation (PRCPTOT) and heavy precipitation days (R10mm). Only 7-35 % of stations showed significant trends, for the other rainfall indices. Spatially, the valley floor received increasing annual rainfall while the escarpments and the highlands received decreasing annual rainfall over the last 40 years. During Belg, 50 % of the stations showed significant increases in the maximum number of consecutive dry days (CDD) in all parts of the CRV. However, most other rainfall indices during Belg showed no significant changes. During Kiremt, considering both significant and non-significant trends, almost all rainfall indices showed an increasing trend in the valley floor and a decreasing trend in the escarpment and highlands. During Belg and Kiremt, the CDD generally showed increasing tendency in the CRV.

  20. Skeletal Indicators of Shark Feeding on Human Remains: Evidence from Florida Forensic Anthropology Cases.

    PubMed

    Stock, Michala K; Winburn, Allysha P; Burgess, George H

    2017-05-02

    This research examines a series of six Florida forensic anthropology cases that exhibit taphonomic evidence of marine deposition and shark-feeding activities. In each case, we analyzed patterns of trauma/damage on the skeletal remains (e.g., sharp-force bone gouges and punctures) and possible mechanisms by which they were inflicted during shark predation/scavenging. In some cases, shark teeth were embedded in the remains; in the absence of this evidence, we measured interdental distance from defects in the bone to estimate shark body length, as well as to draw inferences about the potential species responsible. We discuss similarities and differences among the cases and make comparisons to literature documenting diagnostic shark-inflicted damage to human remains from nearby regions. We find that the majority of cases potentially involve bull or tiger sharks scavenging the remains of previously deceased, adult male individuals. This scavenging results in a distinctive taphonomic signature including incised gouges in cortical bone. © 2017 American Academy of Forensic Sciences.

  1. Auditory-evoked potentials as indicator of brain serotonergic activity--first evidence in behaving cats.

    PubMed

    Juckel, G; Molnár, M; Hegerl, U; Csépe, V; Karmos, G

    1997-06-15

    Due to the increasing importance of the central serotonergic neurotransmission for pathogenetic concepts and as a target of pharmacotherapeutic interventions in psychiatry, reliable indicators of this system are needed. Several findings from basic and clinical research suggest that the stimulus intensity dependence of auditory evoked potentials (AEP) may be such an indicator of behaviorally relevant aspects of serotonergic activity (Hegerl and Juckel 1993, Biol Psychiatry 33:173-187). In order to study this relationship more directly, epidural recordings over the primary and secondary auditory cortex were conducted in chronically implanted cats under intravenous (i.v.) administration of drugs influencing the serotonergic and other modulatory systems (8-OH-DPAT, m-CPP, ketanserin, DOI, apomorphine, atropine, clonidine). The intensity dependence of the cat AEP component with the highest functional similarity to this of the N1/P2-component in humans was significantly changed by influencing 5-HT1a and 5-HT2 receptors, but not 5-HT1c receptors. This serotonergic modulation of the intensity dependence was only found for the primary auditory cortex which corresponds to the known different innervation of the primary and secondary auditory cortex by serotonergic fibers. Our study supports the idea that the intensity dependence of AEP could be a valuable indicator of brain serotonergic activity; however, this indicator seems to be of relative specificity because at least cholinergic effects on the intensity dependence were also observed.

  2. Evidence-Based Practice: Quality Indicator Analysis of Antecedent Exercise in Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Kasner, Melanie; Reid, Greg; MacDonald, Cathy

    2012-01-01

    The purpose of the research was to conduct a quality indicator analysis of studies exploring the effects of antecedent exercise on self-stimulatory behaviors of individuals with autism spectrum disorders (ASD). Educational Resources Information Center (ERIC), Google Scholar, SPORTDiscus, PsychINFO, and PubMed/MedLine databases from 1980 to October…

  3. Quality management: where is the evidence? Developing an indicator-based approach in Kenya.

    PubMed

    Prytherch, Helen; Nafula, Maureen; Kandie, Charles; Brodowski, Marc; Marx, Irmgard; Kubaj, Sandy; Omogi, Irene; Zurkuhlen, Alexia; Herrler, Claudia; Goetz, Katja; Szecsenyi, Joachim; Marx, Michael

    2017-02-01

    The 2030 Sustainable Development Agenda emphasizes the importance of quality of care in the drive to achieve universal health coverage. Despite recent progress, challenges in service delivery, efficiency and resource utilization in the health sector remain. The Ministry of Health Department of Standards and Regulations sought to operationalize the Kenya Quality Assurance Model for Health. To this end, the European Practice Assessment (EPA) was adapted to the area of Reproductive and Maternal and Neonatal Health. The adaptation process made use of a ten step-modified RAND Corporation/University of California Los Angeles (UCLA) Appropriateness Method. The steps included a scoping workshop, definition of five critical domains of quality in the Kenyan context ('People, Management, Clinical Care, Quality & Safety, Interface between inpatients and outpatients care'), a review of policy documents, management and clinical guidelines, grey and scientific literature to identify indicators in use in the Kenyan health system and an expert panel process to rate their feasibility and validity. The resulting 278 indicators, clustered across the five domains, were broken-down into 29 dimensions and assigned measure specifications. A set of data collection tools were developed to furnish the indicators and piloted at two health facilities. They were subsequently finalized for use in 30 health facilities in 3 counties. The integrative and indicator-based aspects of the EPA process could be readily adapted to facilitate the operationalization of a practical quality assurance approach in Kenya.

  4. Evidence-Based Practice: Quality Indicator Analysis of Antecedent Exercise in Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Kasner, Melanie; Reid, Greg; MacDonald, Cathy

    2012-01-01

    The purpose of the research was to conduct a quality indicator analysis of studies exploring the effects of antecedent exercise on self-stimulatory behaviors of individuals with autism spectrum disorders (ASD). Educational Resources Information Center (ERIC), Google Scholar, SPORTDiscus, PsychINFO, and PubMed/MedLine databases from 1980 to October…

  5. Criminogenic Effects of the Prison Environment on Inmate Behavior: Some Experimental Evidence

    ERIC Educational Resources Information Center

    Camp, Scott D.; Gaes, Gerald G.

    2005-01-01

    The current study analyzed a subset of the experimental data collected by Berk, Ladd, Graziano, and Baek (2003) to test whether different intensities of incarceration make inmates more criminal while incarcerated. There were 561 male inmates whose equivalent classification scores indicated they had the same level of risk to commit institutional…

  6. Electrical Resistivity as an Indicator of Saturation in Fractured Geothermal Reservoir Rocks: Experimental Data and Modeling

    SciTech Connect

    Detwiler, R L; Roberts, J J

    2003-06-23

    The electrical resistivity of rock cores under conditions representative of geothermal reservoirs is strongly influenced by the state and phase (liquid/vapor) of the pore fluid. In fractured samples, phase change (vaporization/condensation) can result in resistivity changes that are more than an order of magnitude greater than those measured in intact samples. These results suggest that electrical resistivity monitoring of geothermal reservoirs may provide a useful tool for remotely detecting the movement of water and steam within fractures, the development and evolution of fracture systems and the formation of steam caps. We measured the electrical resistivity of cores of welded tuff containing fractures of various geometries to investigate the resistivity contrast caused by active boiling and to determine the effects of variable fracture dimensions and surface area on water extraction from the matrix. We then used the Nonisothermal Unsaturated Flow and Transport model (NUFT) (Nitao, 1998) to simulate the propagation of boiling fronts through the samples. The simulated saturation profiles combined with previously reported measurements of resistivity-saturation curves allow us to estimate the evolution of the sample resistivity as the boiling front propagates into the rock matrix. These simulations provide qualitative agreement with experimental measurements suggesting that our modeling approach may be used to estimate resistivity changes induced by boiling in more complex systems.

  7. Induced Cannibalism in Experimental Populations of the Forensic Indicator Chrysomya putoria Wiedemann (Diptera: Calliphoridae).

    PubMed

    Botteon, V W; Fernandes, F S; Godoy, W A C

    2016-04-01

    We analyzed the behavior of third-instars of Chrysomya putoria as potential cannibals in experimental populations. Cannibalism rates were evaluated in three settings observed for 3, 6, 9, and 24 h, placing injured and uninjured larvae of C. putoria together. Our data heavily support that C. putoria larvae behave as cannibals when induced by a wound in another larva, and also after starving for 24 h. The probability of cannibalism increased as a function of time, both in no-choice and in choice experiments evidencing that time is a determining factor for cannibalism induction in C. putoria. However, the treatment combining injured with uninjured larvae showed the highest probability of cannibalism. These results suggest that C. putoria larvae may cannibalize under scarcity of food over long time or the presence of injured larvae. This study is useful to understand the behavior of C. putoria feeding on ephemeral substrates such as carrion or corpses and brings relevant and significant contribution to population ecology of blowflies and also forensic entomology.

  8. Experimental Study of Fluid Flow in an Aneurysm for Varying Shape Indices

    NASA Astrophysics Data System (ADS)

    Yu, Paulo; Choi, Cyrus; Durgesh, Vibhav

    2014-11-01

    An aneurysm is an abnormal bulging of a blood vessel wall. A ruptured aneurysm can be severely debilitating or fatal. There is a lack of understanding of fluid flow parameters leading to aneurysm growth and rupture. Clinical studies have shown that certain aneurysm shape indices are strongly correlated to rupture. The overall goal of this study is to comprehensively characterize fluid dynamics parameters inside an aneurysm sac, for varying shape indices. As part of this work, two different idealized aneurysm glass models are used, and an in-house flow loop system has been developed to simulate constant and physiological pressure gradients. Index of refraction matching techniques have been used for accurate estimation of fluid flow parameters. Laser Doppler Velocimetry measurements are conducted for Reynolds number values from 10-200 to understand impact of inflow conditions on flow structures and parameters inside aneurysm sac. Particle Image Velocimetry measurements are performed on several horizontal and vertical planes inside aneurysm sac and show the presence of secondary fluid structures inside the sac, not observed in mid-plane measurements from earlier studies. The results show dependence of flow parameters/structures on aneurysm shape and inflow conditions. This work is supported through the California State University Northridge Research Fellowship Program 2013-14.

  9. Does national scale economic and environmental indicators spur logistics performance? Evidence from UK.

    PubMed

    Khan, Syed Abdul Rehman; Qianli, Dong

    2017-09-27

    The aim of this study is to examine the association between national economic and environmental indicators with green logistics performance in a time series data of UK since 1981 to 2016. The research used autoregressive distributed lag method to understand the long-run and short-run relationships of national scale economic (foreign direct investment (FDI) inflows, per capita income) and environmental indicators (total greenhouse gases, fossil fuel, and renewable energy) on green logistics. In the short run, the research findings indicate that the green logistics and renewable energy have positive relationship, while fossil fuel is negatively correlated with green logistics operations. On the other hand, in the long run, the results show that FDI inflows, renewable energy sources, and per capita income have statistically significant and positive association with green logistics activities, while foreign investments attracted by environmental friendly policies and practices adopted in global logistics operations, which not only increase the environmental sustainability but also enhance economic activities with greater export opportunities in the region.

  10. Gamma-Ray Burst Spectral Indices: Evidence for Deceleration of Synchrotron Shocks

    NASA Technical Reports Server (NTRS)

    Preece, R. D.; Briggs, M. S.; Giblin, T.; Mallozzi, R. S.; Pendleton, G. N.; Paciesas, W. S.; Band, D. L.

    2000-01-01

    The current scenario for gamma-ray bursts (GRBs) involves internal shocks for the prompt GRB emission phase and external shocks for the afterglow phase. Assuming synchrotron emission from energetic shocked electrons. GRB spectra observed with a low-energy power-law spectral index greater than -2/3 (for positive photon number indices E(sup alpha) indicate a problem with this model. The remaining spectra can test the synchrotron shock model prediction that the emission from a single distribution of electrons, cooling rapidly, is responsible for both the low-energy and high-energy power-low portions of the spectra. We find that the inferred relationship between the two spectral indices of observed GRB spectra is inconsistent with the constraints from the model, posing another problem for the synchrotron shock emission model. To overcome this problem, we describe a model where the average of -1, rather than the value of -3/2 predicted for cooling electrons. Situations where this might arise have been discussed in other contexts, and involve deceleration of the internal shocks during the GRB phase.

  11. Experimental Infection of Rhodnius prolixus (Hemiptera, Triatominae) with Mycobacterium leprae Indicates Potential for Leprosy Transmission.

    PubMed

    Neumann, Arthur da Silva; Dias, Felipe de Almeida; Ferreira, Jéssica da Silva; Fontes, Amanda Nogueira Brum; Rosa, Patricia Sammarco; Macedo, Rafael Enrique; Oliveira, José Henrique; Teixeira, Raquel Lima de Figueiredo; Pessolani, Maria Cristina Vidal; Moraes, Milton Ozório; Suffys, Philip Noel; Oliveira, Pedro L; Sorgine, Marcos Henrique Ferreira; Lara, Flavio Alves

    2016-01-01

    Leprosy is a chronic dermato-neurological disease caused by infection with Mycobacterium leprae. In 2013 almost 200,000 new cases of leprosy were detected around the world. Since the first symptoms take from years to decades to appear, the total number of asymptomatic patients is impossible to predict. Although leprosy is one of the oldest records of human disease, the mechanisms involved with its transmission and epidemiology are still not completely understood. In the present work, we experimentally investigated the hypothesis that the mosquitoes Aedes aegypti and Culex quinquefasciatus and the hemiptera Rhodnius prolixus act as leprosy vectors. By means of real-time PCR quantification of M. leprae 16SrRNA, we found that M. leprae remained viable inside the digestive tract of Rhodnius prolixus for 20 days after oral infection. In contrast, in the gut of both mosquito species tested, we were not able to detect M. leprae RNA after a similar period of time. Inside the kissing bug Rhodnius prolixus digestive tract, M. leprae was initially restricted to the anterior midgut, but gradually moved towards the hindgut, in a time course reminiscent of the life cycle of Trypanosoma cruzi, a well-known pathogen transmitted by this insect. The maintenance of M. leprae infectivity inside the digestive tract of this kissing bug is further supported by successful mice footpad inoculation with feces collected 20 days after infection. We conclude that Rhodnius prolixus defecate infective M. leprae, justifying the evaluation of the presence of M. leprae among sylvatic and domestic kissing bugs in countries endemic for leprosy.

  12. Experimental Infection of Rhodnius prolixus (Hemiptera, Triatominae) with Mycobacterium leprae Indicates Potential for Leprosy Transmission

    PubMed Central

    Neumann, Arthur da Silva; Dias, Felipe de Almeida; Ferreira, Jéssica da Silva; Fontes, Amanda Nogueira Brum; Rosa, Patricia Sammarco; Macedo, Rafael Enrique; Oliveira, José Henrique; Teixeira, Raquel Lima de Figueiredo; Pessolani, Maria Cristina Vidal; Moraes, Milton Ozório; Suffys, Philip Noel; Oliveira, Pedro L.; Sorgine, Marcos Henrique Ferreira; Lara, Flavio Alves

    2016-01-01

    Leprosy is a chronic dermato-neurological disease caused by infection with Mycobacterium leprae. In 2013 almost 200,000 new cases of leprosy were detected around the world. Since the first symptoms take from years to decades to appear, the total number of asymptomatic patients is impossible to predict. Although leprosy is one of the oldest records of human disease, the mechanisms involved with its transmission and epidemiology are still not completely understood. In the present work, we experimentally investigated the hypothesis that the mosquitoes Aedes aegypti and Culex quinquefasciatus and the hemiptera Rhodnius prolixus act as leprosy vectors. By means of real-time PCR quantification of M. leprae 16SrRNA, we found that M. leprae remained viable inside the digestive tract of Rhodnius prolixus for 20 days after oral infection. In contrast, in the gut of both mosquito species tested, we were not able to detect M. leprae RNA after a similar period of time. Inside the kissing bug Rhodnius prolixus digestive tract, M. leprae was initially restricted to the anterior midgut, but gradually moved towards the hindgut, in a time course reminiscent of the life cycle of Trypanosoma cruzi, a well-known pathogen transmitted by this insect. The maintenance of M. leprae infectivity inside the digestive tract of this kissing bug is further supported by successful mice footpad inoculation with feces collected 20 days after infection. We conclude that Rhodnius prolixus defecate infective M. leprae, justifying the evaluation of the presence of M. leprae among sylvatic and domestic kissing bugs in countries endemic for leprosy. PMID:27203082

  13. Ischemia modified albumin increase indicating cardiac damage after experimental subarachnoid hemorrhage

    PubMed Central

    2014-01-01

    Background Cardiac complications are often developed after subarachnoid hemorrhage (SAH) and may cause sudden death of the patient. There are reports in the literature addressing ischemia modified albumin (IMA) as an early and useful marker in the diagnosis of ischemic heart events. The aim of this study is to evaluate serum IMA by using the albumin cobalt binding (ACB) test in the first, second, and seventh days of experimental SAH in rats. Twenty-eight Wistar albino rats were divided into four groups each consisting of seven animals. These were classified as control group, 1st, 2nd and 7th day SAH groups. SAH was done by transclival basilar artery puncture. Blood samples were collected under anesthesia from the left ventricles of the heart using the cardiac puncture method for IMA measurement. Histopathological examinations were performed on the heart and lung tissues. Albumin with by colorimetric, creatine kinase (CK), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) were determined on an automatic analyser using the enzymatic method. IMA using by ACB test was detected with spectrophotometer. Results Serum IMA (p = 0.044) in seventh day of SAH were higher compared to the control group. Total injury scores of heart and lung tissue, also myocytolysis at day 7 were significantly higher than control group (p = 0.001, p = 0.001, p = 0.001), day 1 (p = 0.001, p = 0.001, p = 0.001) and day 2 (p = 0.001, p = 0.007, p = 0.001). A positive correlation between IMA - myocytolysis (r = 0.48, p = 0.008), and between IMA – heart tissue total injury score (r = 0.41, p = 0.029) was found. Conclusion The results revealed that increased serum IMA may be related to myocardial stress after SAH. PMID:24564759

  14. Estimation of postmortem interval in real cases based on experimentally obtained entomological evidence.

    PubMed

    Arnaldos, M I; García, M D; Romera, E; Presa, J J; Luna, A

    2005-04-20

    Using the entomological evidence obtained in several forensic cases analyzed in our laboratory for comparison, we evaluated the results of an experimental study carried out in a semiurban setting to determine the structure of the sarcosaprophagous fauna from a Mediterranean region of SE Spain. In all, 18 orders of arthropods were collected. The summarized experimental results refer to the most important taxa for estimating the postmortem interval. Thus, the seasonal character of certain Diptera species, such as Phaenicia sericata, Calliphora vicina, Chrysomya albiceps and Musca domestica, is cited. Among the Coleoptera, the role of Dermestidae as a necrophagous species, and of Staphylinidae and Histeridae as necrophilous, or Cleridae, Tenebrionidae and Nitidulidae as omnivorous, as well as their appearance on the corpse, is described. Among the Hymenoptera, Formicidae were as the most abundant group, acting as omnivores and not apparently related to any particular decomposition stage. The real cases are discussed using data from the literature and the experimentally obtained results. In every case, the most relevant factors for estimating PMI are briefly discussed, mentioning, when possible, the relation with the experimental results. We confirm the significance of the experimental results because they seem to be applicable to actual forensic cases, the details of which enlarge our very little knowledge on the subject in the Iberian Peninsula. The importance of regional faunistic studies of the sarcosaprophagous arthropod community, the results of which may be applied to forensic practice, is mentioned.

  15. Can trade opportunities and returns be generated in a trend persistent series? Evidence from global indices

    NASA Astrophysics Data System (ADS)

    Mitra, S. K.; Bawa, Jaslene

    2017-03-01

    In this study, we explore the possibility of generating trade opportunities and returns when a financial stock index series is trend persistent. Through application of Hurst coefficient based on the modified range to standard deviation analysis (Weron, 2002) in a sample of 31 leading global indices during the period December 2000 to November 2015, we found periods of trend persistence. We developed and tested a set of trading strategies on these periods of trend persistent in the financial series and found that significant positive returns can be generated when a series displayed upward trend persistence.

  16. Cordierite monzogranites of the Hercynian Iberian Massif: experimental indicators for a hybrid origin

    NASA Astrophysics Data System (ADS)

    García-Moreno, O.; Castro, A.; Corretgé, L. G.; Klimm, K.; Holtz, F.

    2003-04-01

    Cordierite-bearing monzogranites form one of the three main groups of granitic rocks in the Hercynian Iberian massif, together with peraluminous leucogranites and biotite granodiorites. The moderate calcium contents (CaO up to 1,21wt%) as well as the low Sr initial isotope ratio of these monzogranite rocks cannot be explained by a pure crustal origin as in the case of the peraluminous leucogranites. The composition of the "most mafic" rock (a cordierite monzogranite) of the Cabeza de Araya pluton (Cáceres, Spain) was chosen to synthesize a glass used in a series of crystallization experiments at different conditions. Phase relations found in these experiments do not reproduce the natural mineral assemblage for the ferromagnesian phases at pressures ranging from 200 to 600 MPa and temperatures from 700 °C to 975 °C, independently on water activity (from water-undersaturated to -saturated conditions with initial H2O in the system: 2wt%, 4wt% and 6wt%). Cordierite failed to crystallize and pyroxenes and hercynitic spinel, which are never found in these rocks in nature, crystallized in our experiments. Oxygen fugacity in the experiments is below the QFM buffer, which may be close to natural conditions of genesis of these granites due to the presence of graphite in the metasediments that may be the crustal protolith. These results are not in agreement with the clearly magmatic features of cordierite crystals in the natural monzogranite. Seeds of natural cordierite crystals (#Mg0= 0,50) were added to the synthetic glass to check for possible nucleation problems of cordierite in the experiments but cordierite was systematically dissolved in the melts at high temperature. Reaction of the cordierite seeds with melt to form plagioclase (up to An60) could be observed in an experiment (750 °C/ 200 MPa/ initial 4wt% H2O) (Crd + Ca-rich melt -> Pl). Our experimental results can only be explained if we consider that the cordierite monzogranites never were a primary liquid, in

  17. Isotopic evidence indicates saprotrophy in post-fire Morchella in Oregon and Alaska.

    PubMed

    Hobbie, Erik A; Rice, Samuel F; Weber, Nancy S; Smith, Jane E

    2016-01-01

    We assessed the nutritional strategy of true morels (genus Morchella) collected in 2003 and 2004 in Oregon and Alaska, 1 or 2 y after forest fires. We hypothesized that the patterns of stable isotopes (δ(13)C and δ(15)N) in the sporocarps would match those of saprotrophic fungi and that radiocarbon (Δ(14)C) analyses would indicate that Morchella was assimilating old carbon not current-year photosynthate. We compared radiocarbon and stable isotopes in Morchella with values from concurrently collected foliage, the ectomycorrhizal Geopyxis carbonaria (Alb. & Schwein.) Sacc., the saprotrophic Plicaria endocarpoides (Berk.) Rifai, and with literature to determine isotopic values for ectomycorrhizal or saprotrophic fungi. Geopyxis, Plicaria and Morchella, respectively, were 3‰, 5‰ and 6‰ higher in 13C than foliage and 5‰, 7‰ and 7‰ higher in (15)N. High (15)N enrichment in Morchella indicated that recent litter was not the primary source for Morchella nitrogen, and similar (13)C and (15)N enrichments to Plicaria suggest that Morchella assimilates its carbon and nitrogen from the same source pool as this saprotrophic fungus. From radiocarbon analyses Morchella averaged 11 ± 6 y old (n = 19), Plicaria averaged 17 ± 5 y old (n = 3), foliage averaged 1 ± 2 y old (n = 8) and Geopyxis (n = 1) resembled foliage in Δ(14)C. We conclude that morels fruiting in post-fire environments in our study assimilated old carbon and were saprotrophic.

  18. Archaeogenetic Evidence of Ancient Nubian Barley Evolution from Six to Two-Row Indicates Local Adaptation

    PubMed Central

    Palmer, Sarah A.; Moore, Jonathan D.; Clapham, Alan J.; Rose, Pamela; Allaby, Robin G.

    2009-01-01

    Background Archaeobotanical samples of barley (Hordeum vulgare L.) found at Qasr Ibrim display a two-row phenotype that is unique to the region of archaeological sites upriver of the first cataract of the Nile, characterised by the development of distinctive lateral bracts. The phenotype occurs throughout all strata at Qasr Ibrim, which range in age from 3000 to a few hundred years. Methodology and Findings We extracted ancient DNA from barley samples from the entire range of occupancy of the site, and studied the Vrs1 gene responsible for row number in extant barley. Surprisingly, we found a discord between the genotype and phenotype in all samples; all the barley had a genotype consistent with the six-row condition. These results indicate a six-row ancestry for the Qasr Ibrim barley, followed by a reassertion of the two-row condition. Modelling demonstrates that this sequence of evolutionary events requires a strong selection pressure. Conclusions The two-row phenotype at Qasr Ibrim is caused by a different mechanism to that in extant barley. The strength of selection required for this mechanism to prevail indicates that the barley became locally adapted in the region in response to a local selection pressure. The consistency of the genotype/phenotype discord over time supports a scenario of adoption of this barley type by successive cultures, rather than the importation of new barley varieties associated with individual cultures. PMID:19623249

  19. Sustainability indices as a tool for urban managers, evidence from four medium-sized Chinese cities

    SciTech Connect

    Dijk, Meine Pieter van . E-mail: mpvandijk@few.eur.nl; Zhang Mingshun . E-mail: z.mingshun@ihs.nl

    2005-08-15

    This research in four medium-sized Chinese cities aims at measuring urban sustainability in China and focuses on three issues. First, the situation in these four cities with regard to urban sustainability is evaluated. Secondly, a number of relations between different aspects of urban sustainability is explored. Finally, it is indicated how urban managers can improve with sustainability indices as tools currently ineffective urban management practices. Although all four cities are moving towards sustainable development, the current situation shows still weak sustainability in three, and even non-sustainability in one city. The social and, in particular, the economic dimensions of urban sustainability make significant positive contributions to overall urban sustainability. However, the decline of natural resources and environmental degradation are influencing it negatively. It is therefore suggested that more priority should be assigned to urban environmental protection and management in China. The fundamental reason for environmental degradation is believed to be inefficient urban management. To implement effective urban management in China, there is an urgent need to redefine the role of local government, reform local organizational structure, enhance local participatory institutional capacity, properly distribute the urban welfare, and thus integrate economic, social and environmental objectives local strategic and action plans.

  20. Theory and experimental evidence of phonon domains and their roles in pre-martensitic phenomena

    NASA Astrophysics Data System (ADS)

    Jin, Yongmei M.; Wang, Yu U.; Ren, Yang

    2015-12-01

    Pre-martensitic phenomena, also called martensite precursor effects, have been known for decades while yet remain outstanding issues. This paper addresses pre-martensitic phenomena from new theoretical and experimental perspectives. A statistical mechanics-based Grüneisen-type phonon theory is developed. On the basis of deformation-dependent incompletely softened low-energy phonons, the theory predicts a lattice instability and pre-martensitic transition into elastic-phonon domains via 'phonon spinodal decomposition.' The phase transition lifts phonon degeneracy in cubic crystal and has a nature of phonon pseudo-Jahn-Teller lattice instability. The theory and notion of phonon domains consistently explain the ubiquitous pre-martensitic anomalies as natural consequences of incomplete phonon softening. The phonon domains are characterised by broken dynamic symmetry of lattice vibrations and deform through internal phonon relaxation in response to stress (a particular case of Le Chatelier's principle), leading to previously unexplored new domain phenomenon. Experimental evidence of phonon domains is obtained by in situ three-dimensional phonon diffuse scattering and Bragg reflection using high-energy synchrotron X-ray single-crystal diffraction, which observes exotic domain phenomenon fundamentally different from usual ferroelastic domain switching phenomenon. In light of the theory and experimental evidence of phonon domains and their roles in pre-martensitic phenomena, currently existing alternative opinions on martensitic precursor phenomena are revisited.

  1. The impact of free trial acceptance on demand for alternative nicotine products: evidence from experimental auctions.

    PubMed

    Rousu, Matthew C; O'Connor, Richard J; Bansal-Travers, Maansi; Pitcavage, James M; Thrasher, James F

    2015-06-11

    This study explored the relationship between product trials and consumer demand for alternative nicotine products (ANP). An experimental auction was conducted with 258 adult smokers, wherein participants were randomly assigned to one of four experimental conditions. The participants received the opportunity to try, but did not have to accept, one of three relatively novel ST products (i.e., snus, dissolvable tobacco, or medicinal nicotine), or they were placed into a control group (i.e., no trial). All the participants then bid on all three of these products, as well as on cigarettes. We assessed interest in using ANP based on both trial of the product and bids placed for the products in the experimental auction. Fewer smokers were willing to try snus (44%) than dissolvable tobacco (64%) or medicine nicotine (68%). For snus, we find modest evidence suggesting that willingness to try is associated with greater demand for the product. For dissolvable tobacco or medicinal nicotine, we find no evidence that those who accept the product trial have higher demand for the product. Free trials of a novel ANP were not strongly associated with product demand, as assessed by willingness to pay. Given the debate over the potential for ANP to reduce the harm from smoking, these results are important in understanding the impact of free trial offers on adoption of ST product as a strategy to reduce harm from tobacco use.

  2. Selected CSF biomarkers indicate no evidence of early neuroinflammation in Huntington disease

    PubMed Central

    Vinther-Jensen, Tua; Börnsen, Lars; Budtz-Jørgensen, Esben; Ammitzbøll, Cecilie; Larsen, Ida U.; Hjermind, Lena E.; Sellebjerg, Finn

    2016-01-01

    Objective: To investigate CSF biomarkers of neuroinflammation and neurodegeneration in Huntington disease (HD) gene-expansion carriers compared to controls and to investigate these biomarkers in association with clinical HD rating scales and disease burden score. Methods: We collected CSF from 32 premanifest and 48 manifest HD gene-expansion carriers and 24 gene-expansion negative at-risk controls. We examined biomarkers of neuroinflammation (matrix metalloproteinase 9, C-X-C motif chemokine 13, terminal complement complex, chitinase-3-like-protein 1 [CHI3L1], and osteopontin [OPN]) and neurodegeneration (microtubule-associated protein tau, neurofilament light polypeptide [NFL], and myelin basic protein [MBP]). The study was approved by the Ethics Committee of the Capital Region of Denmark (H2-2011-085) and written informed consent was obtained from each participant before enrollment. Results: NFL was the only biomarker that increased in premanifest stages and no evidence of early involvement of neuroinflammation in HD was found. However, we found that the biomarkers for neurodegeneration, MBP and tau, increased during the disease course in manifest HD gene-expansion carriers and were associated with an increase of the neuroinflammation biomarkers CHI3L1 and OPN. Tau was also increased in all gene-expansion carriers with psychiatric symptoms compared to gene-expansion carriers without psychiatric symptoms. Conclusions: Neuroinflammation, which seems not to be an early event in our cohort, may be secondary to neurodegeneration in late HD. NFL is a possible disease burden correlate in HD, reflecting neuronal loss even before motor symptom onset, and may be useful as a dynamic biomarker in intervention studies. PMID:27734023

  3. Determinants of relative and absolute concentration indices: evidence from 26 European countries

    PubMed Central

    2013-01-01

    Introduction The aim of publicly-provided health care is generally not only to produce health, but also to decrease variation in health by socio-economic status. The aim of this study is to measure to what extent this goal has been obtained in various European countries and evaluate the determinants of inequalities within countries, as well as cross-country patterns with regard to different cultural, institutional and social settings. Methods The data utilized in this study provides information on 440,000 individuals in 26 European countries and stem from The European Union Statistics on Income and Living Conditions (EU-SILC) collected in 2007. As measures of income-related inequality in health both the relative concentration indices and the absolute concentration indices are calculated. Further, health inequality in each country is decomposed into individual-level determinants and cross-country comparisons are made to shed light on social and institutional determinants. Results Income-related health inequality favoring the better-off is observed for all the 26 European countries. In terms of within-country determinants inequality is mainly explained by income, age, education, and activity status. However, the degree of inequality and contribution of each determinant to inequality varies considerably between countries. Aggregate bivariate linear regressions show that there is a positive association between health-income inequality in Europe and public expenditure on education. Furthermore, a negative relationship between health-income inequality and income inequality was found when individual employee cash income was used in the health-concentration measurement. Using that same income measure, health-income inequality was found to be higher in the Nordic countries than in other areas, but this result is sensitive to the income measure chosen. Conclusions The findings indicate that institutional determinants partly explain income-related health inequalities across

  4. Library residencies and internships as indicators of success: evidence from three programs.

    PubMed Central

    Lanier, D; Henderson, C L

    1999-01-01

    This paper discusses post-master's degree internships in three very different organizations; the University of Illinois at Chicago, the National Library of Medicine, and the Library of Congress. It discusses the internships using several questions. Do the programs serve as a recruitment strategy? Do the programs develop key competencies needed by the participant or organization? Do the programs develop leaders and managers? Is acceptance into a program an indicator of future career success? A survey was mailed to 520 persons who had completed internships in one of the three programs. There was a 49.8% response rate. Responses to fifty-four questions were tabulated and analyzed for each program and for the total group. The results confirm the value of internships to the career of participants. PMID:10219479

  5. Are Front of Pack Claims Indicators of Nutrition Quality? Evidence from 2 Product Categories.

    PubMed

    Schaefer, Debra; Hooker, Neal H; Stanton, John L

    2016-01-01

    American grocery shoppers face an array of front of pack (FOP) nutrition and health claims when making food selections. Such systems have been categorized as summary or nutrient specific. Either type should help consumers make judgments about the nutrition quality of a product. This research tests if the type or quantity of FOP claims are indeed good indicators of objective nutrition quality. Claim and nutrition information from more than 2200 breakfast cereals and prepared meals launched between 2006 and 2010 were analyzed using binary and multinomial logistic regression models. Results suggest that no type or number of front of pack claims could distinguish "healthy" foods. However, some types and frequencies of FOP claims were significant predictors of higher or lower levels of certain key nutrients. Given the complex and crowded label environment in which these FOP claims reside, one may be concerned that such cues are not closely related to objective measures of nutrition quality.

  6. Geomorphic Indicators of Ground Ice on Mars and Evidence for Climate Change

    NASA Astrophysics Data System (ADS)

    Mustard, J. F.

    2003-12-01

    Until recently, indications of the presence of ice in the near surface of Mars, outside the polar caps, has depended upon the interpretation of morphology from imaging data. Early work in this area was based primarily on Viking orbiter images where several large landforms (100s to 1000s of meters in scale) were interpreted to be related to the presence of ice in the regolith or upper crust. These include lineated valley fill, concentric crater fill, softened terrain, and polygons, and are typically found between the latitudes of 30° -60° N and S. Without direct measurements of the presence of water, the interpretations rely on analogies with Earth's periglacial and glacial morphologies as well as geophysical modeling of ice-rich soils and crustal material. New spacecraft data from the Mars Global Surveyor and Mars Odyssey missions have significantly added to the family of morphologies with ground-ice affinities. From the high spatial resolution images acquired by Mars Orbiter Camera (MOC) a new array of polygons have been detected which range in size from 25-200 m and show strong latitudinal gradients above 50° . A possibly related morphology exhibiting a regularly spaced surface texture resembling the texture of a basketball is also found in these high latitudes. A number of morphologies indicating viscous flow on steep slopes are found in the mid-latitudes and are consistent with an ice-rich soils deforming under martian surface conditions. A continuous deposit, meters-thick and interpreted to be ice rich is observed at latitudes above 60° , but that is in a degraded condition at lower latitudes (formerly ice-rich) and absent in the equatorial regions (within 30° ). The neutron spectrometer on the Odyssey spacecraft made direct measurements of hydrogen which shows clearly the presence of high water-ice abundance (>70% by volume) in the surface soils in the northern and southern latitudes above 60° . This critical observation ties in well with theoretical

  7. Relevance of the Glutathione System in Temporal Lobe Epilepsy: Evidence in Human and Experimental Models

    PubMed Central

    Cárdenas-Rodríguez, Noemí; Coballase-Urrutia, Elvia; Pérez-Cruz, Claudia; Montesinos-Correa, Hortencia; Rivera-Espinosa, Liliana; Sampieri, Aristides; Carmona-Aparicio, Liliana

    2014-01-01

    Oxidative stress, which is a state of imbalance in the production of reactive oxygen species and nitrogen, is induced by a wide variety of factors. This biochemical state is associated with diseases that are systemic as well as diseases that affect the central nervous system. Epilepsy is a chronic neurological disorder, and temporal lobe epilepsy represents an estimated 40% of all epilepsy cases. Currently, evidence from human and experimental models supports the involvement of oxidative stress during seizures and in the epileptogenesis process. Hence, the aim of this review was to provide information that facilitates the processing of this evidence and investigate the therapeutic impact of the biochemical status for this specific pathology. PMID:25538816

  8. Additional experimental evidence for a solar influence on nuclear decay rates

    NASA Astrophysics Data System (ADS)

    Jenkins, Jere H.; Herminghuysen, Kevin R.; Blue, Thomas E.; Fischbach, Ephraim; Javorsek, Daniel; Kauffman, Andrew C.; Mundy, Daniel W.; Sturrock, Peter A.; Talnagi, Joseph W.

    2012-09-01

    Additional experimental evidence is presented in support of the recent hypothesis that a possible solar influence could explain fluctuations observed in the measured decay rates of some isotopes. These data were obtained during routine weekly calibrations of an instrument used for radiological safety at The Ohio State University Research Reactor using 36Cl. The detector system used was based on a Geiger-Müller gas detector, which is a robust detector system with very low susceptibility to environmental changes. A clear annual variation is evident in the data, with a maximum relative count rate observed in January/February, and a minimum relative count rate observed in July/August, for seven successive years from July 2005 to June 2011. This annual variation is not likely to have arisen from changes in the detector surroundings, as we show here.

  9. Sound Scattering by a Hard Half-Plane Experimental Evidence of the Edge-Diffracted Wave

    NASA Astrophysics Data System (ADS)

    OUIS, D.

    2002-05-01

    In this short note, some experimental results are presented on the diffraction of a spherical way by a hard half-plane. This study was conducted with the aim to give evidence to the existence of the edge-diffracted wave. The sound source used in this experimental study is a condenser microphone operating in a reverse way. The wave emitted by a sound source propagates in space and hits a thin aluminium sheet with a straight edge, considered as an idealization of the hard half-plane. The resulting impulse response includes among others a wave diffracted by the edge of the half-plane, which is compared to its theoretical prediction. This latter is calculated from the exact Biot and Tolstoy solution to the problem of diffraction of a spherical wave by a hard wedge. Relatively satisfactory agreement is found between theory and experiment.

  10. Experimental evidence for allosteric modifier saturation as predicted by the bi-substrate Hill equation.

    PubMed

    Hanekom, A J; Hofmeyr, J H S; Snoep, J L; Rohwer, J M

    2006-09-01

    The cooperative enzyme reaction rates predicted by the bi-substrate Hill equation and the bi-substrate Monod-Wyman-Changeux (MWC) equation when allosterically inhibited are compared in silico. Theoretically, the Hill equation predicts that when the maximum inhibitory effect at a certain substrate condition has been reached, an increase in allosteric inhibitor concentration will have no effect on reaction rate, that is the Hill equation shows allosteric inhibitor saturation. This saturating inhibitory effect is not present in the MWC equation. Experimental in vitro data for pyruvate kinase, a bi-substrate cooperative enzyme that is allosterically inhibited, are presented. This enzyme also shows inhibitor saturation, and therefore serves as experimental evidence that the bi-substrate Hill equation predicts more realistic allosteric inhibitor behaviour than the bi-substrate MWC equation.

  11. Permanent dissipative structures in water: the matrix of life? Experimental evidences and their quantum origin.

    PubMed

    Elia, V; Germano, R; Napoli, E

    2015-01-01

    This paper presents a short review of the evidence - both experimental and theoretical - of the formation of dissipative structures in liquid water induced by three kinds of physical perturbations having a low energy content: extremely diluted solution (EDS), iteratively filtered water (IFW), and iteratively nafionated water (INW). Particular attention is devoted to the very recent discovery that such structures are tremendously persistent even in the solid phase: large ponderal quantities of supramolecular aggregates of water (with each nucleus hundreds of nanometers in size) have been observed - at ambient pressure and temperature - using easily-reproducible experimental methods. The nature of these dissipative structures is analyzed and explained in terms of the thermodynamics of far-from-equilibrium systems and irreversible processes, showing their spontaneous quantum origin. Are these kinds of structures the matrix itself of life?.

  12. Poverty, inequality, and increased consumption of high calorie food: Experimental evidence for a causal link.

    PubMed

    Bratanova, Boyka; Loughnan, Steve; Klein, Olivier; Claassen, Almudena; Wood, Robert

    2016-05-01

    Rising obesity represents a serious, global problem. It is now well established that obesity is associated with poverty and wealth inequality, suggesting that these factors may promote caloric intake. Whereas previous work has examined these links from an epidemiological perspective, the current paper examined them experimentally. In Study 1 we found that people experimentally induced to view themselves as poor (v. wealthy) exhibited increased calorie intake. In Study 2, participants who believed that they were poorer or wealthier than their interaction partners exhibited higher levels of anxiety compared to those in an equal partners condition; this anxiety in turn led to increased calorie consumption for people who had a strong need to belong. The findings provide causal evidence for the poverty-intake and inequality-intake links. Further, we identify social anxiety and a strong need to belong as important social psychological factors linking inequality to increased calorie intake. Copyright © 2016. Published by Elsevier Ltd.

  13. Experimental evidence of high-frequency complete elastic bandgap in pillar-based phononic slabs

    SciTech Connect

    Pourabolghasem, Reza; Mohammadi, Saeed; Eftekhar, Ali A.; Adibi, Ali; Khelif, Abdelkrim

    2014-12-08

    We present strong experimental evidence for the existence of a complete phononic bandgap, for Lamb waves, in the high frequency regime (i.e., 800 MHz) for a pillar-based phononic crystal (PnC) membrane with a triangular lattice of gold pillars on top. The membrane is composed of an aluminum nitride film stacked on thin molybdenum and silicon layers. Experimental characterization shows a large attenuation of at least 20 dB in the three major crystallographic directions of the PnC lattice in the frequency range of 760 MHz–820 MHz, which is in agreement with our finite element simulations of the PnC bandgap. The results of experiments are analyzed and the physics behind the attenuation in different spectral windows is explained methodically by assessing the type of Bloch modes and the in-plane symmetry of the displacement profile.

  14. Evidence of Experimental Bias in the Life Sciences: Why We Need Blind Data Recording

    PubMed Central

    Lanfear, Robert; Jennions, Michael D.

    2015-01-01

    Observer bias and other “experimenter effects” occur when researchers’ expectations influence study outcome. These biases are strongest when researchers expect a particular result, are measuring subjective variables, and have an incentive to produce data that confirm predictions. To minimize bias, it is good practice to work “blind,” meaning that experimenters are unaware of the identity or treatment group of their subjects while conducting research. Here, using text mining and a literature review, we find evidence that blind protocols are uncommon in the life sciences and that nonblind studies tend to report higher effect sizes and more significant p-values. We discuss methods to minimize bias and urge researchers, editors, and peer reviewers to keep blind protocols in mind. PMID:26154287

  15. Computer modelling and experimental evidence for two steady states in the photosynthetic Calvin cycle.

    PubMed

    Poolman, M G; Olçer, H; Lloyd, J C; Raines, C A; Fell, D A

    2001-05-01

    We present observations of photosynthetic carbon dioxide assimilation, and leaf starch content from genetically modified tobacco (Nicotiana tabacum) plants in which the activity of the Calvin cycle enzyme, sedoheptulose-1,7-bisphosphatase, is reduced by an antisense construct. The measurements were made on leaves of varying ages and used to calculate the flux control coefficients of sedoheptulose-1,7-bisphosphatase over photosynthetic assimilation and starch synthesis. These calculations suggest that control coefficients for both are negative in young leaves, and positive in mature leaves. This behaviour is compared to control coefficients obtained from a detailed computer model of the Calvin cycle. The comparison demonstrates that the experimental observations are consistent with bistable behaviour exhibited by the model, and provides the first experimental evidence that such behaviour in the Calvin cycle occurs in vivo as well as in silico.

  16. Evidence for a bimodal distribution of hybrid indices in a hybrid zone with high admixture

    PubMed Central

    McKenzie, Jessica L.; Dhillon, Rashpal S.; Schulte, Patricia M.

    2015-01-01

    The genetic structure of a hybrid zone can provide insights into the relative roles of the various factors that maintain the zone. Here, we use a multilocus approach to characterize a hybrid zone between two subspecies of killifish (Fundulus heteroclitus, Walbaum 1792) found along the Atlantic coast of North America. We first analysed clinal variation along the Atlantic coast using a single-nucleotide polymorphism in the mitochondrial DNA (mtDNA) displacement loop (D-loop) and a panel of nine nuclear microsatellite markers. A model constraining all clines to the same width and centre was not significantly different from a model in which the clines were allowed to vary independently. Locus-by-locus analysis indicated that the majority of nuclear clines shared the same centre as the mtDNA cline, and the widths of these clines were also narrower than that predicted by a neutral model, suggesting that selection is operating to maintain the hybrid zone. However, two of the nuclear clines had widths greater than the neutral prediction and had centres that were displaced relative to the mtDNA cline centre. We also found that a marsh located near the centre of the mtDNA cline demonstrated a bimodal distribution of nuclear hybrid index values, suggesting a deficit of first-generation hybrids and backcrossed genotypes. Thus, selection against hybrid genotypes may be playing a role in maintaining this hybrid zone and the associated steep nuclear and mtDNA clines. PMID:27019720

  17. Mineralogical Indicators for Climate Change on Mars: Evidence from Landed Missions

    NASA Technical Reports Server (NTRS)

    Ming, D. W.; Morris, R. V.; Clark, B. C.

    2015-01-01

    Mineralogical and geochemical data returned by a flotilla of Mars orbiters and landers over the past 10 years has substantially enhanced our understanding on the evolution of the atmosphere and climate. Instruments onboard Mars Express and MRO discovered widespread deposits of phyllosilicates that formed during the Noachian followed by formation of sulfates into the Hesperian. The formation of extensive valley networks along with these layered deposits of phyllosilicates and sulfates during the late Noachian/ early Hesperian indicate a past martian climate that was capable of maintaining liquid water at the surface. The planet's climate changed substantially after these early 'episodes' of water and very little aqueous alteration has occurred over the past 3.5 Gyrs . A key to understanding Mars past climate is to identify, characterize, and age date secondary minerals that have formed by reaction with volatile compounds, e.g., H2O, CO2, SO2. Here, we summarize the detection of secondary minerals at the four landing sites visited over the past 10 years. We also provide potential pathways for their formation and implications for past climate change on Mars.

  18. Experimental evidence for homeostatic sex allocation after sex-biased reintroductions.

    PubMed

    Linklater, Wayne Leslie; Law, Peter Roy; Gedir, Jay Vinson; du Preez, Pierre

    2017-03-06

    First principles predict negative frequency-dependent sex allocation, but it is unproven in field studies and seldom considered, despite far-reaching consequences for theory and practice in population genetics and dynamics as well as animal ecology and behaviour. Twenty-four years of rhinoceros calving after 45 reintroductions across southern Africa provide the first in situ experimental evidence that unbalanced operational sex ratios predicted offspring sex and offspring sex ratios. Our understanding of population dynamics, especially reintroduction and invasion biology, will be significantly impacted by these findings.

  19. Direct experimental evidence for atomic tunneling of europium in crystalline Eu8Ga16Ge30.

    PubMed

    Hermann, Raphaël P; Keppens, Veerle; Bonville, Pierre; Nolas, George S; Grandjean, Fernande; Long, Gary J; Christen, Hans M; Chakoumakos, Bryan C; Sales, Brian C; Mandrus, David

    2006-07-07

    Mössbauer-effect and microwave absorption experimental evidence unambiguously demonstrates the presence of slow, approximately 450 MHz, tunneling of magnetic europium between four equivalent sites in Eu8Ga16Ge30, a stoichiometric clathrate. Remarkably, six of the eight europium atoms, or 11% of the constituents in this solid, tunnel between these four sites separated by 0.55 A. The off centering of the atoms or ions in crystalline clathrates appears to be a promising route for producing Rabi oscillators in solid-state materials.

  20. Experimental and theoretical evidence for fluctuation driven activations in an excitable chemical system

    NASA Astrophysics Data System (ADS)

    Hastings, Harold; Sobel, Sabrina; Field, Richard; Minchenberg, Scott; Spinelli, Nicole; Zauderer, Keith

    2011-03-01

    An excitable medium is a system in which small perturbations die out, but sufficiently large perturbations generate large ``excitations.'' Biological examples include neurons and the heart; the latter supports waves of excitation normally generated by the sinus node, but occasionally generated by other mechanisms. The ferroin-catalyzed Belousov-Zhabotinsky reaction is the prototype chemical excitable medium. We present experimental and theoretical evidence for that random fluctuations can generate excitations in the Belousov-Zhabothinsky reaction. Although the heart is significantly different, there are some scaling analogies. This material is based upon work supported by the Department of Energy under Award Number DE-FG02-08ER64623.

  1. Experimental evidence of a symbiosis between red-cockaded woodpeckers and fungi.

    PubMed

    Jusino, Michelle A; Lindner, Daniel L; Banik, Mark T; Rose, Kevin R; Walters, Jeffrey R

    2016-03-30

    Primary cavity excavators, such as woodpeckers, are ecosystem engineers in many systems. Associations between cavity excavators and fungi have long been hypothesized to facilitate cavity excavation, but these relationships have not been experimentally verified. Fungi may help excavators by softening wood, while excavators may facilitate fungal dispersal. Here we demonstrate that excavators facilitate fungal dispersal and thus we report the first experimental evidence of a symbiosis between fungi and a cavity excavator, the red-cockaded woodpecker (RCW,Picoides borealis). Swab samples of birds showed that RCWs carry fungal communities similar to those found in their completed excavations. A 26-month field experiment using human-made aseptically drilled excavations in live trees, half of which were inaccessible to RCWs, demonstrated that RCWs directly alter fungal colonization and community composition. Experimental excavations that were accessible to RCWs contained fungal communities similar to natural RCW excavations, whereas inaccessible experimental excavations contained significantly different fungal communities. Our work demonstrates a complex symbiosis between cavity excavators and communities of fungi, with implications for forest ecology, wildlife management, and conservation.

  2. Experimental evidence of a symbiosis between red-cockaded woodpeckers and fungi

    PubMed Central

    Banik, Mark T.; Rose, Kevin R.; Walters, Jeffrey R.

    2016-01-01

    Primary cavity excavators, such as woodpeckers, are ecosystem engineers in many systems. Associations between cavity excavators and fungi have long been hypothesized to facilitate cavity excavation, but these relationships have not been experimentally verified. Fungi may help excavators by softening wood, while excavators may facilitate fungal dispersal. Here we demonstrate that excavators facilitate fungal dispersal and thus we report the first experimental evidence of a symbiosis between fungi and a cavity excavator, the red-cockaded woodpecker (RCW, Picoides borealis). Swab samples of birds showed that RCWs carry fungal communities similar to those found in their completed excavations. A 26-month field experiment using human-made aseptically drilled excavations in live trees, half of which were inaccessible to RCWs, demonstrated that RCWs directly alter fungal colonization and community composition. Experimental excavations that were accessible to RCWs contained fungal communities similar to natural RCW excavations, whereas inaccessible experimental excavations contained significantly different fungal communities. Our work demonstrates a complex symbiosis between cavity excavators and communities of fungi, with implications for forest ecology, wildlife management, and conservation. PMID:27009222

  3. Colloid-induced kidney injury: experimental evidence may help to understand mechanisms

    PubMed Central

    Schortgen, Frédérique; Brochard, Laurent

    2009-01-01

    Fluid resuscitation is widely used, and many patients are therefore exposed to plasma volume expanders. Among these, colloids, particularly hydroxyethyl starches, have been shown in recent experiments and clinical studies to induce acute kidney injury. The mechanisms of colloid-induced acute kidney injury remain incompletely elucidated. The risks associated with colloid osmotic pressure elevation in vivo and the high incidence of osmotic nephrosis lesions in experimental models and clinical studies indicate that hydroxyethyl starches can no longer be considered safe. PMID:19435473

  4. Experimental evidence for reciprocity in allogrooming among wild-type Norway rats.

    PubMed

    Schweinfurth, Manon K; Stieger, Binia; Taborsky, Michael

    2017-06-21

    If individuals help more those who have previously helped them, stable cooperation may ensue through alternation of roles between donors and recipients. Allogrooming, which is costly to donors and beneficial to recipients, is often exchanged between social partners. Arguably, allogrooming and allopreening are the most frequently exchanged social services and have been used as a standard model of reciprocal cooperation. However, evidence for the application of reciprocity rules among social partners allogrooming each other hitherto is merely correlational. Here, we tested whether female Norway rats (Rattus norvegicus) apply the decision rule characterising direct reciprocity: help someone who has helped you before, by experimentally manipulating both the need for allogrooming and the behavioural response. Furthermore, we checked whether trading of grooming services is influenced by the rank of the social partner. We show that rats groom social partners reciprocally and prefer to do so up the hierarchy, i.e. they groom dominant partners more often than subordinates, while reciprocating with both. This provides experimental evidence that animals render a costly social service by applying reciprocity decision rules when showing a natural hygienic behaviour. The fact that allogrooming is more readily shown up the hierarchy may suggest an appeasing function.

  5. Delayed school start times and adolescent sleep: A systematic review of the experimental evidence.

    PubMed

    Minges, Karl E; Redeker, Nancy S

    2016-08-01

    Many schools have instituted later morning start times to improve sleep, academic, and other outcomes in response to the mismatch between youth circadian rhythms and early morning start times. However, there has been no systematic synthesis of the evidence on the effects of this practice. To examine the impact of delayed school start time on students' sleep, health, and academic outcomes, electronic databases were systematically searched and data were extracted using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Six studies satisfied selection criteria and used pre-post, no control (n = 3), randomized controlled trial (n = 2), and quasi-experimental (n = 1) designs. School start times were delayed 25-60 min, and correspondingly, total sleep time increased from 25 to 77 min per weeknight. Some studies revealed reduced daytime sleepiness, depression, caffeine use, tardiness to class, and trouble staying awake. Overall, the evidence supports recent non-experimental study findings and calls for policy that advocates for delayed school start time to improve sleep. This presents a potential long-term solution to chronic sleep restriction during adolescence. However, there is a need for rigorous randomized study designs and reporting of consistent outcomes, including objective sleep measures and consistent measures of health and academic performance.

  6. Delayed School Start Times and Adolescent Sleep: A Systematic Review of the Experimental Evidence

    PubMed Central

    Minges, Karl E.; Redeker, Nancy S.

    2016-01-01

    Summary Many schools have instituted later morning start times to improve sleep, academic, and other outcomes in response to the mismatch between youth circadian rhythms and early morning start times. However, there has been no systematic synthesis of the evidence on the effects of this practice. To examine the impact of delayed school start time on students’ sleep, health, and academic outcomes, electronic databases were systematically searched and data were extracted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Six studies satisfied selection criteria and used pre-post, no control (n=3), randomized controlled trial (n=2), and quasi-experimental (n=1) designs. School start times were delayed 25 to 60 minutes, and correspondingly, total sleep time increased from 25 to 77 minutes per weeknight. Some studies revealed reduced daytime sleepiness, depression, caffeine use, tardiness to class, and trouble staying awake. Overall, the evidence supports recent non-experimental study findings and calls for policy that advocates for delayed school start time to improve sleep. This presents a potential long-term solution to chronic sleep restriction during adolescence. However, there is a need for rigorous randomized study designs and reporting of consistent outcomes, including objective sleep measures and consistent measures of health and academic performance. PMID:26545246

  7. Experimental evidences of topological surface states of β-Ag2Te

    NASA Astrophysics Data System (ADS)

    Sulaev, Azat; Ren, Peng; Xia, Bin; Lin, Qing Hua; Yu, Ting; Qiu, Caiyu; Zhang, Shuang-Yuan; Han, Ming-Yong; Li, Zhi Peng; Zhu, Wei Guang; Wu, Qingyu; Feng, Yuan Ping; Shen, Lei; Shen, Shun-Qing; Wang, Lan

    2013-03-01

    We present evidence of topological surface states in β-Ag2Te through first-principles calculations, periodic quantum interference effect and ambipolar electric field effect in single crystalline nanoribbon. Our first-principles calculations show that β-Ag2Te is a topological insulator with a gapless Dirac cone with strong anisotropy. To experimentally probe the topological surface state, we synthesized high quality β-Ag2Te nanoribbons and performed electron transport measurements. The coexistence of pronounced Aharonov-Bohm oscillations and weak Altshuler-Aronov-Spivak oscillations clearly demonstrates coherent electron transport around the perimeter of β-Ag2Te nanoribbon and therefore the existence of topological surface states, which is further supported by the ambipolar electric field effect for devices fabricated by β-Ag2Te nanoribbons. The experimental evidences of topological surface states and the theoretically predicted anisotropic Dirac cone of β-Ag2Te suggest that the material may be a promising candidate of topological insulator for fundamental study and future spintronic devices.

  8. Reliability of Growth Indicators and Efficiency of Functional Treatment for Skeletal Class II Malocclusion: Current Evidence and Controversies

    PubMed Central

    2017-01-01

    Current evidence on the reliability of growth indicators in the identification of the pubertal growth spurt and efficiency of functional treatment for skeletal Class II malocclusion, the timing of which relies on such indicators, is highly controversial. Regarding growth indicators, the hand and wrist (including the sole middle phalanx of the third finger) maturation method and the standing height recording appear to be most reliable. Other methods are subjected to controversies or were showed to be unreliable. Main sources of controversies include use of single stages instead of ossification events and diagnostic reliability conjecturally based on correlation analyses. Regarding evidence on the efficiency of functional treatment, when treated during the pubertal growth spurt, more favorable response is seen in skeletal Class II patients even though large individual responsiveness remains. Main sources of controversies include design of clinical trials, definition of Class II malocclusion, and lack of inclusion of skeletal maturity among the prognostic factors. While no growth indicator may be considered to have a full diagnostic reliability in the identification of the pubertal growth spurt, their use may still be recommended for increasing efficiency of functional treatment for skeletal Class II malocclusion. PMID:28168195

  9. Reliability of Growth Indicators and Efficiency of Functional Treatment for Skeletal Class II Malocclusion: Current Evidence and Controversies.

    PubMed

    Perinetti, Giuseppe; Contardo, Luca

    2017-01-01

    Current evidence on the reliability of growth indicators in the identification of the pubertal growth spurt and efficiency of functional treatment for skeletal Class II malocclusion, the timing of which relies on such indicators, is highly controversial. Regarding growth indicators, the hand and wrist (including the sole middle phalanx of the third finger) maturation method and the standing height recording appear to be most reliable. Other methods are subjected to controversies or were showed to be unreliable. Main sources of controversies include use of single stages instead of ossification events and diagnostic reliability conjecturally based on correlation analyses. Regarding evidence on the efficiency of functional treatment, when treated during the pubertal growth spurt, more favorable response is seen in skeletal Class II patients even though large individual responsiveness remains. Main sources of controversies include design of clinical trials, definition of Class II malocclusion, and lack of inclusion of skeletal maturity among the prognostic factors. While no growth indicator may be considered to have a full diagnostic reliability in the identification of the pubertal growth spurt, their use may still be recommended for increasing efficiency of functional treatment for skeletal Class II malocclusion.

  10. Experimental Evidence Linking Elevated CO2, Rhizosphere C/N Stoichiometry and Microbial Efficiency

    NASA Astrophysics Data System (ADS)

    Carrillo, Y.; Dijkstra, F. A.; Pendall, E.; LeCain, D. R.; Morgan, J.

    2012-12-01

    expected to be more efficient in their C use. Decreasing the C/N ratio of roots decreased SOM respiration and increased the efficiency of SOM-consuming microbes. Direct N additions had a similar but stronger effect. Increased C efficiency with greater nutrient availability is consistent with theoretical expectations of C utilization under nutrient limitation. Notably, the response of C use to N treatments occurred only under eCO2 conditions. This functional contrast was supported by differential responses of microbial PLFA profiles to N treatments under CO2 treatments. Together, these results suggest that the eCO2 environment was more conducive to N limitation, via changes in microbial community structure and function. Our results provide direct experimental evidence of plant-mediated alteration of decomposer C efficiency due to changes in atmospheric CO2 and N availability from both plant and soil sources. An increase in SOM-consuming microbes efficiency in an eCO2 world is likely to have important ecosystem-level implications as it could enhance the amount of C that remains in soil relative to the amount released to the atmosphere. The interactive effects of CO2 and N treatments suggest that microbial efficiency will be more sensitive to changes in nutrient status under the future eCO2 atmosphere.

  11. Arsenic Exposure and Type 2 Diabetes: A Systematic Review of the Experimental and Epidemiologic Evidence

    PubMed Central

    Navas-Acien, Ana; Silbergeld, Ellen K.; Streeter, Robin A.; Clark, Jeanne M.; Burke, Thomas A.; Guallar, Eliseo

    2006-01-01

    Chronic arsenic exposure has been suggested to contribute to diabetes development. We performed a systematic review of the experimental and epidemiologic evidence on the association of arsenic and type 2 diabetes. We identified 19 in vitro studies of arsenic and glucose metabolism. Five studies reported that arsenic interfered with transcription factors involved in insulin-related gene expression: upstream factor 1 in pancreatic β-cells and peroxisome proliferative-activated receptor γ in preadipocytes. Other in vitro studies assessed the effect of arsenic on glucose uptake, typically using very high concentrations of arsenite or arsenate. These studies provide limited insight on potential mechanisms. We identified 10 in vivo studies in animals. These studies showed inconsistent effects of arsenic on glucose metabolism. Finally, we identified 19 epidemiologic studies (6 in high-arsenic areas in Taiwan and Bangladesh, 9 in occupational populations, and 4 in other populations). In studies from Taiwan and Bangladesh, the pooled relative risk estimate for diabetes comparing extreme arsenic exposure categories was 2.52 (95% confidence interval, 1.69–3.75), although methodologic problems limit the interpretation of the association. The evidence from occupational studies and from general populations other than Taiwan or Bangladesh was inconsistent. In summary, the current available evidence is inadequate to establish a causal role of arsenic in diabetes. Because arsenic exposure is widespread and diabetes prevalence is reaching epidemic proportions, experimental studies using arsenic concentrations relevant to human exposure and prospective epidemiologic studies measuring arsenic biomarkers and appropriately assessing diabetes should be a research priority. PMID:16675414

  12. In situ and experimental evidence for acidic weathering of rocks and soils on Mars

    NASA Astrophysics Data System (ADS)

    Hurowitz, J. A.; McLennan, S. M.; Tosca, N. J.; Arvidson, R. E.; Michalski, J. R.; Ming, D. W.; Schröder, C.; Squyres, S. W.

    2006-01-01

    Experimental data for alteration of synthetic Martian basalts at pH = 0-1 indicate that chemical fractionations at low pH are vastly different from those observed during terrestrial weathering. Rock surface analyses from Gusev crater are well described by the relationships apparent from low-pH experimental alteration data. A model for rock surface alteration is developed, which indicates that a leached alteration zone is present on rock surfaces at Gusev. This zone is not chemically fractionated to a large degree from the underlying rock interior, indicating that the rock surface alteration process has occurred at low water to rock ratio. The geochemistry of natural rock surfaces analyzed by APXS is consistent with a mixture between adhering soil/dust and the leached alteration zone. The chemistry of rock surfaces analyzed after brushing with the RAT is largely representative of the leached alteration zone. The chemistry of rock surfaces analyzed after grinding with the RAT is largely representative of the interior of the rock, relatively unaffected by the alteration process occurring at the rock surface. Elemental measurements from the Spirit, Opportunity, Pathfinder, and Viking 1 landing sites indicate that soil chemistry from widely separated locations is consistent with the low-pH, low water to rock ratio alteration relationships developed for Gusev rocks. Soils are affected principally by mobility of Fe and Mg, consistent with alteration of olivine-bearing basalt and subsequent precipitation of Fe- and Mg-bearing secondary minerals as the primary control on soil geochemistry.

  13. Experimental evidence for drought induced alternative stable states of soil moisture.

    PubMed

    Robinson, David A; Jones, Scott B; Lebron, Inma; Reinsch, Sabine; Domínguez, María T; Smith, Andrew R; Jones, Davey L; Marshall, Miles R; Emmett, Bridget A

    2016-01-25

    Ecosystems may exhibit alternative stable states (ASS) in response to environmental change. Modelling and observational data broadly support the theory of ASS, however evidence from manipulation experiments supporting this theory is limited. Here, we provide long-term manipulation and observation data supporting the existence of drought induced alternative stable soil moisture states (irreversible soil wetting) in upland Atlantic heath, dominated by Calluna vulgaris (L.) Hull. Manipulated repeated moderate summer drought, and intense natural summer drought both lowered resilience resulting in shifts in soil moisture dynamics. The repeated moderate summer drought decreased winter soil moisture retention by ~10%. However, intense summer drought, superimposed on the experiment, that began in 2003 and peaked in 2005 caused an unexpected erosion of resilience and a shift to an ASS; both for the experimental drought manipulation and control plots, impairing the soil from rewetting in winter. Measurements outside plots, with vegetation removal, showed no evidence of moisture shifts. Further independent evidence supports our findings from historical soil moisture monitoring at a long-term upland hydrological observatory. The results herald the need for a new paradigm regarding our understanding of soil structure, hydraulics and climate interaction.

  14. Experimental evidence for drought induced alternative stable states of soil moisture

    PubMed Central

    Robinson, David. A.; Jones, Scott B.; Lebron, Inma; Reinsch, Sabine; Domínguez, María T.; Smith, Andrew R.; Jones, Davey L.; Marshall, Miles R.; Emmett, Bridget A.

    2016-01-01

    Ecosystems may exhibit alternative stable states (ASS) in response to environmental change. Modelling and observational data broadly support the theory of ASS, however evidence from manipulation experiments supporting this theory is limited. Here, we provide long-term manipulation and observation data supporting the existence of drought induced alternative stable soil moisture states (irreversible soil wetting) in upland Atlantic heath, dominated by Calluna vulgaris (L.) Hull. Manipulated repeated moderate summer drought, and intense natural summer drought both lowered resilience resulting in shifts in soil moisture dynamics. The repeated moderate summer drought decreased winter soil moisture retention by ~10%. However, intense summer drought, superimposed on the experiment, that began in 2003 and peaked in 2005 caused an unexpected erosion of resilience and a shift to an ASS; both for the experimental drought manipulation and control plots, impairing the soil from rewetting in winter. Measurements outside plots, with vegetation removal, showed no evidence of moisture shifts. Further independent evidence supports our findings from historical soil moisture monitoring at a long-term upland hydrological observatory. The results herald the need for a new paradigm regarding our understanding of soil structure, hydraulics and climate interaction. PMID:26804897

  15. Resilience of experimentally seeded dietary traditions in wild vervets: Evidence from group fissions.

    PubMed

    van de Waal, Erica; van Schaik, Carel P; Whiten, Andrew

    2017-10-01

    Controlled laboratory experiments have delivered extensive and compelling evidence for the diffusion and maintenance of socially learned behavior in primates and other animals. Such evidence is rarer in the wild, but we show that a behavior seeded in a majority of individuals within vervet monkey (Chlorocebus pygerythus) groups may be sustained across several years. Here, we report results of two natural fission events in such groups that offer novel evidence of the resilience of socially transmitted group norms of behavior. Before fission, high ranked females exhibited an almost exclusive adherence to a group preference among two food options, originally introduced through a distasteful additive in one option, but no longer present in repeated later tests. Because of rank-dependent competition, low-ranked females ate more of the formerly distasteful food and so discovered it was now as palatable as the alternative. Despite this experience, low ranked females who formed the splinter groups then expressed a 100% bias for the preferred option of their original parent group, revealing these preferences to be resilient. We interpret this effect as conformity to either the preferences of high rankers or of a majority in the parent group, or both. However, given fissioned individuals' familiarity with their habitat and experimental options, we question the adequacy of the informational function usually ascribed to conformity and discuss alternatives under a concept of "social conformity". © 2017 Wiley Periodicals, Inc.

  16. Experimental evidence for drought induced alternative stable states of soil moisture

    NASA Astrophysics Data System (ADS)

    Robinson, David. A.; Jones, Scott B.; Lebron, Inma; Reinsch, Sabine; Domínguez, María T.; Smith, Andrew R.; Jones, Davey L.; Marshall, Miles R.; Emmett, Bridget A.

    2016-01-01

    Ecosystems may exhibit alternative stable states (ASS) in response to environmental change. Modelling and observational data broadly support the theory of ASS, however evidence from manipulation experiments supporting this theory is limited. Here, we provide long-term manipulation and observation data supporting the existence of drought induced alternative stable soil moisture states (irreversible soil wetting) in upland Atlantic heath, dominated by Calluna vulgaris (L.) Hull. Manipulated repeated moderate summer drought, and intense natural summer drought both lowered resilience resulting in shifts in soil moisture dynamics. The repeated moderate summer drought decreased winter soil moisture retention by ~10%. However, intense summer drought, superimposed on the experiment, that began in 2003 and peaked in 2005 caused an unexpected erosion of resilience and a shift to an ASS; both for the experimental drought manipulation and control plots, impairing the soil from rewetting in winter. Measurements outside plots, with vegetation removal, showed no evidence of moisture shifts. Further independent evidence supports our findings from historical soil moisture monitoring at a long-term upland hydrological observatory. The results herald the need for a new paradigm regarding our understanding of soil structure, hydraulics and climate interaction.

  17. Live Fast, Die Young: Experimental Evidence of Population Extinction Risk due to Climate Change

    PubMed Central

    Bestion, Elvire; Teyssier, Aimeric; Richard, Murielle; Clobert, Jean; Cote, Julien

    2015-01-01

    Evidence has accumulated in recent decades on the drastic impact of climate change on biodiversity. Warming temperatures have induced changes in species physiology, phenology, and have decreased body size. Such modifications can impact population dynamics and could lead to changes in life cycle and demography. More specifically, conceptual frameworks predict that global warming will severely threaten tropical ectotherms while temperate ectotherms should resist or even benefit from higher temperatures. However, experimental studies measuring the impacts of future warming trends on temperate ectotherms' life cycle and population persistence are lacking. Here we investigate the impacts of future climates on a model vertebrate ectotherm species using a large-scale warming experiment. We manipulated climatic conditions in 18 seminatural populations over two years to obtain a present climate treatment and a warm climate treatment matching IPCC predictions for future climate. Warmer temperatures caused a faster body growth, an earlier reproductive onset, and an increased voltinism, leading to a highly accelerated life cycle but also to a decrease in adult survival. A matrix population model predicts that warm climate populations in our experiment should go extinct in around 20 y. Comparing our experimental climatic conditions to conditions encountered by populations across Europe, we suggest that warming climates should threaten a significant number of populations at the southern range of the distribution. Our findings stress the importance of experimental approaches on the entire life cycle to more accurately predict population and species persistence in future climates. PMID:26501958

  18. Live Fast, Die Young: Experimental Evidence of Population Extinction Risk due to Climate Change.

    PubMed

    Bestion, Elvire; Teyssier, Aimeric; Richard, Murielle; Clobert, Jean; Cote, Julien

    2015-10-01

    Evidence has accumulated in recent decades on the drastic impact of climate change on biodiversity. Warming temperatures have induced changes in species physiology, phenology, and have decreased body size. Such modifications can impact population dynamics and could lead to changes in life cycle and demography. More specifically, conceptual frameworks predict that global warming will severely threaten tropical ectotherms while temperate ectotherms should resist or even benefit from higher temperatures. However, experimental studies measuring the impacts of future warming trends on temperate ectotherms' life cycle and population persistence are lacking. Here we investigate the impacts of future climates on a model vertebrate ectotherm species using a large-scale warming experiment. We manipulated climatic conditions in 18 seminatural populations over two years to obtain a present climate treatment and a warm climate treatment matching IPCC predictions for future climate. Warmer temperatures caused a faster body growth, an earlier reproductive onset, and an increased voltinism, leading to a highly accelerated life cycle but also to a decrease in adult survival. A matrix population model predicts that warm climate populations in our experiment should go extinct in around 20 y. Comparing our experimental climatic conditions to conditions encountered by populations across Europe, we suggest that warming climates should threaten a significant number of populations at the southern range of the distribution. Our findings stress the importance of experimental approaches on the entire life cycle to more accurately predict population and species persistence in future climates.

  19. Direct experimental evidence for a multiparticle-hole ground state configuration of deformed 33Mg

    NASA Astrophysics Data System (ADS)

    Datta, Ushasi; Rahaman, A.; Aumann, T.; Beceiro-Novo, S.; Boretzky, K.; Caesar, C.; Carlson, B. V.; Catford, W. N.; Chakraborty, S.; Chartier, M.; Cortina-Gil, D.; de Angelis, G.; Diaz Fernandez, P.; Emling, H.; Ershova, O.; Fraile, L. M.; Geissel, H.; Gonzalez-Diaz, D.; Jonson, B.; Johansson, H.; Kalantar-Nayestanaki, N.; Kröll, T.; Krücken, R.; Kurcewicz, J.; Langer, C.; Le Bleis, T.; Leifels, Y.; Marganiec, J.; Münzenberg, G.; Najafi, M. A.; Nilsson, T.; Nociforo, C.; Panin, V.; Paschalis, S.; Plag, R.; Reifarth, R.; Ricciardi, V.; Rossi, D.; Scheit, H.; Scheidenberger, C.; Simon, H.; Taylor, J. T.; Togano, Y.; Typel, S.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Weigand, M.; Winfield, J. S.; Yakorev, D.; Zoric, M.

    2016-09-01

    The first direct experimental evidence of a multiparticle-hole ground state configuration of the neutron-rich 33Mg isotope has been obtained via intermediate energy (400 A MeV) Coulomb dissociation measurement. The major part ˜(70 ±13 )% of the cross section is observed to populate the excited states of 32Mg after the Coulomb breakup of 33Mg. The shapes of the differential Coulomb dissociation cross sections in coincidence with different core excited states favor that the valence neutron occupies both the s1 /2 and p3 /2 orbitals. These experimental findings suggest a significant reduction and merging of s d -p f shell gaps at N ˜20 and 28. The ground state configuration of 33Mg is predominantly a combination of 32Mg(3.0 ,3.5 MeV ;2-,1-) ⨂νs1/2 , 32Mg(2.5 MeV ;2+) ⨂νp3/2 , and 32Mg(0 ;0+) ⨂νp3/2 . The experimentally obtained quantitative spectroscopic information for the valence neutron occupation of the s and p orbitals, coupled with different core states, is in agreement with Monte Carlo shell model (MCSM) calculation using 3 MeV as the shell gap at N =20 .

  20. Voltammetric Thin-Layer Ionophore-Based Films: Part 1. Experimental Evidence and Numerical Simulations.

    PubMed

    Yuan, Dajing; Cuartero, Maria; Crespo, Gaston A; Bakker, Eric

    2017-01-03

    Voltammetric thin layer (∼200 nm) ionophore-based polymeric films of defined ion-exchange capacity have recently emerged as a promising approach to acquire multi-ion information about the sample, in analogy to performing multiple potentiometric measurements with individual membranes. They behave under two different regimes that are dependent on the ion concentration. A thin layer control (no mass transport limitation of the polymer film or solution) is identified for ion concentrations of >10 μM, in which case the peak potential serves as the readout signal, in analogy to a potentiometric sensor. On the other hand, ion transfer at lower concentrations is chiefly controlled by diffusional mass transport from the solution to the sensing film, resulting in an increase of peak current with ion concentration. This concentration range is suitable for electrochemical ion transfer stripping analysis. Here, the transition between the two mentioned scenarios is explored experimentally, using a highly silver-selective membrane as a proof-of-concept under different conditions (variation of ion concentration in the sample from 0.1 μM to 1 mM, scan rate from 25 mV s(-1) to 200 mV s(-1), and angular frequency from 100 rpm to 6400 rpm). Apart from experimental evidence, a numerical simulation is developed that considers an idealized conducting polymer behavior and permits one to predict experimental behavior under diffusion or thin-layer control.

  1. Curriculum-based measurement oral reading as an indicator of reading achievement: a meta-analysis of the correlational evidence.

    PubMed

    Reschly, Amy L; Busch, Todd W; Betts, Joseph; Deno, Stanley L; Long, Jeffrey D

    2009-12-01

    This meta-analysis summarized the correlational evidence of the association between the CBM Oral Reading measure (R-CBM) and other standardized measures of reading achievement for students in grades 1-6. Potential moderating variables were also examined (source of criterion test, administration format, grade level, length of time, and type of reading subtest score). Results indicated a significant, strong overall correlation among R-CBM and other standardized tests of reading achievement and differences in correlations as a function of source of test, administration format, and reading subtest type. No differences in the magnitude of correlations were found across grade levels. In addition, there was minimal evidence of publication bias. Results are discussed in terms of existing literature and directions for future research.

  2. Experimental evidence rejects pairwise modelling approach to coexistence in plant communities

    PubMed Central

    Dormann, Carsten F; Roxburgh, Stephen H

    2005-01-01

    Competition is often invoked as the cause of plant species loss with increasing system productivity. Experimental results for multispecies assemblages are virtually absent and mathematical models are thus used to explore the relationship between competition and coexistence. Modelling approaches to coexistence and diversity in competitive communities commonly employ Lotka–Volterra-type (LV) models with additive pairwise competitive effects. Using pairwise plant competition experiments, we calibrate the LV system and use it to predict plant biomass and coexistence in six three-species and one seven-species experimental mixture. Our results show that five out of the six three-species sets and the seven-species set deviate significantly from LV model predictions. Fitting an additional non-additive competition coefficient resulted in predictions that more closely matched the experimental results, with stable coexistence suggested in all but one case. These results are discussed with particular reference to the possible underlying mechanisms of coexistence in our experimental community. Modelling the effect of competition intensity on stability indicates that if non-additive effects occur, they will be relevant over a wide range of community sizes. Our findings caution against relying on coexistence predictions based on LV models. PMID:16024393

  3. Sudden Cardiac Risk Stratification with Electrocardiographic Indices - A Review on Computational Processing, Technology Transfer, and Scientific Evidence.

    PubMed

    Gimeno-Blanes, Francisco J; Blanco-Velasco, Manuel; Barquero-Pérez, Óscar; García-Alberola, Arcadi; Rojo-Álvarez, José L

    2016-01-01

    Great effort has been devoted in recent years to the development of sudden cardiac risk predictors as a function of electric cardiac signals, mainly obtained from the electrocardiogram (ECG) analysis. But these prediction techniques are still seldom used in clinical practice, partly due to its limited diagnostic accuracy and to the lack of consensus about the appropriate computational signal processing implementation. This paper addresses a three-fold approach, based on ECG indices, to structure this review on sudden cardiac risk stratification. First, throughout the computational techniques that had been widely proposed for obtaining these indices in technical literature. Second, over the scientific evidence, that although is supported by observational clinical studies, they are not always representative enough. And third, via the limited technology transfer of academy-accepted algorithms, requiring further meditation for future systems. We focus on three families of ECG derived indices which are tackled from the aforementioned viewpoints, namely, heart rate turbulence (HRT), heart rate variability (HRV), and T-wave alternans. In terms of computational algorithms, we still need clearer scientific evidence, standardizing, and benchmarking, siting on advanced algorithms applied over large and representative datasets. New scenarios like electronic health recordings, big data, long-term monitoring, and cloud databases, will eventually open new frameworks to foresee suitable new paradigms in the near future.

  4. Sudden Cardiac Risk Stratification with Electrocardiographic Indices - A Review on Computational Processing, Technology Transfer, and Scientific Evidence

    PubMed Central

    Gimeno-Blanes, Francisco J.; Blanco-Velasco, Manuel; Barquero-Pérez, Óscar; García-Alberola, Arcadi; Rojo-Álvarez, José L.

    2016-01-01

    Great effort has been devoted in recent years to the development of sudden cardiac risk predictors as a function of electric cardiac signals, mainly obtained from the electrocardiogram (ECG) analysis. But these prediction techniques are still seldom used in clinical practice, partly due to its limited diagnostic accuracy and to the lack of consensus about the appropriate computational signal processing implementation. This paper addresses a three-fold approach, based on ECG indices, to structure this review on sudden cardiac risk stratification. First, throughout the computational techniques that had been widely proposed for obtaining these indices in technical literature. Second, over the scientific evidence, that although is supported by observational clinical studies, they are not always representative enough. And third, via the limited technology transfer of academy-accepted algorithms, requiring further meditation for future systems. We focus on three families of ECG derived indices which are tackled from the aforementioned viewpoints, namely, heart rate turbulence (HRT), heart rate variability (HRV), and T-wave alternans. In terms of computational algorithms, we still need clearer scientific evidence, standardizing, and benchmarking, siting on advanced algorithms applied over large and representative datasets. New scenarios like electronic health recordings, big data, long-term monitoring, and cloud databases, will eventually open new frameworks to foresee suitable new paradigms in the near future. PMID:27014083

  5. Gluconeogenesis in the ruminant fetus: evaluation of conflicting evidence from radiotracer and other experimental techniques

    SciTech Connect

    Prior, R.L.

    1982-01-01

    Conflicting evidence exists as to whether the gluconeogenetic process is active in the late gestation fetal lamb. In vitro evidence based on measurements of enzyme activity and substrate flux into glucose indicates that the capacity for gluconeogenesis exists in fetal liver. The in vivo conversion of (/sup 14/C)lactate and (/sup 14/C)alanine into glucose in the lamb fetus has been demonstrated. Lactate and alanine account for 49 and 2.3% of the fetal glucose pool, respectively. Although gluconeogenesis can occur in the fetal lamb, alterations in net rates of umbilical uptake of glucose or lactate, fetal blood glucose concentrations, fetal or maternal glucose replacement rates, or maternal nutrition may alter the observed rates of fetal gluconeogenesis.

  6. Experimental evidence in support of Joule heating associated with geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Devries, L. L.

    1971-01-01

    High resolution accelerometer measurements in the altitude region 140 to 300 km from a satellite in a near-polar orbit during a period of extremely high geomagnetic activity indicate that Joule heating is the primary source of energy for atmospheric heating associated with geomagnetic activity. This conclusion is supported by the following observational evidence: (1) There is an atmospheric response in the auroral zone which is nearly simulataneous with the onset of geomagnetic activity, with no significant response in the equatorial region until several hours later; (2) The maximum heating occurs at geographic locations near the maximum current of the auroral electrojet; and (3) There is evidence of atmospheric waves originating near the auroral zone at altitudes where Joule heating would be expected to occur. An analysis of atmospheric response time to this heat shows time delays are apparently independent of altitude but are strongly dependent upon geomagnetic latitude.

  7. Variations in achievement of evidence-based, high-impact quality indicators in general practice: An observational study

    PubMed Central

    West, Robert; Rushforth, Bruno; Stokes, Tim; Glidewell, Liz; Carder, Paul; Faulkner, Simon; Foy, Robbie

    2017-01-01

    Background There are widely recognised variations in the delivery and outcomes of healthcare but an incomplete understanding of their causes. There is a growing interest in using routinely collected ‘big data’ in the evaluation of healthcare. We developed a set of evidence-based ‘high impact’ quality indicators (QIs) for primary care and examined variations in achievement of these indicators using routinely collected data in the United Kingdom (UK). Methods Cross-sectional analysis of routinely collected, electronic primary care data from a sample of general practices in West Yorkshire, UK (n = 89). The QIs covered aspects of care (including processes and intermediate clinical outcomes) in relation to diabetes, hypertension, atrial fibrillation, myocardial infarction, chronic kidney disease (CKD) and ‘risky’ prescribing combinations. Regression models explored the impact of practice and patient characteristics. Clustering within practice was accounted for by including a random intercept for practice. Results Median practice achievement of the QIs ranged from 43.2% (diabetes control) to 72.2% (blood pressure control in CKD). Considerable between-practice variation existed for all indicators: the difference between the highest and lowest performing practices was 26.3 percentage points for risky prescribing and 100 percentage points for anticoagulation in atrial fibrillation. Odds ratios associated with the random effects for practices emphasised this; there was a greater than ten-fold difference in the likelihood of achieving the hypertension indicator between the lowest and highest performing practices. Patient characteristics, in particular age, gender and comorbidity, were consistently but modestly associated with indicator achievement. Statistically significant practice characteristics were identified less frequently in adjusted models. Conclusions Despite various policy and improvement initiatives, there are enduring inappropriate variations in the

  8. Experimental evidence of a helical, supercritical instability in pipe flow of shear thinning fluids

    NASA Astrophysics Data System (ADS)

    Picaut, L.; Ronsin, O.; Caroli, C.; Baumberger, T.

    2017-08-01

    We study experimentally the flow stability of entangled polymer solutions extruded through glass capillaries. We show that the pipe flow becomes linearly unstable beyond a critical value (Wic≃5 ) of the Weissenberg number, via a supercritical bifurcation which results in a helical distortion of the extrudate. We find that the amplitude of the undulation vanishes as the aspect ratio L /R of the capillary tends to zero, and saturates for large L /R , indicating that the instability affects the whole pipe flow, rather than the contraction or exit regions. These results, when compared to previous theoretical and experimental works, lead us to argue that the nature of the instability is controlled by the level of shear thinning of the fluids. In addition, we provide strong hints that the nonlinear development of the instabiilty is mitigated, in our system, by the gradual emergence of gross wall slip.

  9. Experimental evidence that electrical fatigue failure obeys a generalized Coffin-Manson law

    NASA Astrophysics Data System (ADS)

    He, Xiangtong; Fu, John Y.

    2017-05-01

    The empirical Coffin-Manson law has been used to characterize the low-cycle mechanical fatigue failure of metallic materials for decades. Our experimental studies reported in this letter have shown that the electrical fatigue failure in dielectrics can be well described by a fitting function having the same mathematical expression as that of the Coffin-Manson law. This observation indicates that the physical mechanism beneath the formation and evolution of atomic disordered structures, the key factor influencing both mechanical and electrical fatigue, might be the same.

  10. The Scientific Consensus on Climate Change as a Gateway Belief: Experimental Evidence

    PubMed Central

    van der Linden, Sander L.; Leiserowitz, Anthony A.; Feinberg, Geoffrey D.; Maibach, Edward W.

    2015-01-01

    There is currently widespread public misunderstanding about the degree of scientific consensus on human-caused climate change, both in the US as well as internationally. Moreover, previous research has identified important associations between public perceptions of the scientific consensus, belief in climate change and support for climate policy. This paper extends this line of research by advancing and providing experimental evidence for a “gateway belief model” (GBM). Using national data (N = 1104) from a consensus-message experiment, we find that increasing public perceptions of the scientific consensus is significantly and causally associated with an increase in the belief that climate change is happening, human-caused and a worrisome threat. In turn, changes in these key beliefs are predictive of increased support for public action. In short, we find that perceived scientific agreement is an important gateway belief, ultimately influencing public responses to climate change. PMID:25714347

  11. Behavioural evidence of magnetoreception in dolphins: detection of experimental magnetic fields.

    PubMed

    Kremers, Dorothee; López Marulanda, Juliana; Hausberger, Martine; Lemasson, Alban

    2014-11-01

    Magnetoreception, meaning the perception of magnetic fields, is supposed to play an important role for orientation/navigation in some terrestrial and aquatic species. Although some spatial observations of free-ranging cetaceans' migration routes and stranding sites led to the assumption that cetaceans may be sensitive to the geomagnetic field, experimental evidence is lacking. Here, we tested the spontaneous response of six captive bottlenose dolphins to the presentation of two magnetized and demagnetized controlled devices while they were swimming freely. Dolphins approached the device with shorter latency when it contained a strongly magnetized neodymium block compared to a control demagnetized block that was identical in form and density and therefore undistinguishable with echolocation. We conclude that dolphins are able to discriminate the two stimuli on the basis of their magnetic properties, a prerequisite for magnetoreception-based navigation.

  12. Hypertension and Dementia: Epidemiological and Experimental Evidence Revealing a Detrimental Relationship

    PubMed Central

    Perrotta, Marialuisa; Lembo, Giuseppe; Carnevale, Daniela

    2016-01-01

    Hypertension and dementia represent two major public health challenges worldwide, notably in the elderly population. Although these two conditions have classically been recognized as two distinct diseases, mounting epidemiological, clinical and experimental evidence suggest that hypertension and dementia are strictly intertwined. Here, we briefly report how hypertension profoundly affects brain homeostasis, both at the structural and functional level. Chronic high blood pressure modifies the cerebral vasculature, increasing the risk of Aβ clearance impairment. The latter, excluding genetic etiologies, is considered one of the main causes of Aβ deposition in the brain. Studies have shown that hypertension induces cerebral arterial stiffening and microvascular dysfunction, thus contributing to dementia pathophysiology. This review examines the existing and the updated literature which has attempted to explain and clarify the relationship between hypertension and dementia at the pathophysiological level. PMID:27005613

  13. First Experimental Evidence for the Transmission of Chlamydia psittaci in Poultry through Eggshell Penetration.

    PubMed

    Ahmed, B; De Boeck, C; Dumont, A; Cox, E; De Reu, K; Vanrompay, D

    2017-02-01

    Eggshell penetration by pathogens is considered a potential route for their transmission in poultry flocks. Additionally, in case of zoonotic pathogens, contact with infected eggs or their consumption can result in human infection. Chlamydia psittaci is a zoonotic bacterium that causes a respiratory disease in poultry and humans. In this study, we provide an experimental evidence for eggshell penetration by C. psittaci. Additionally, we show that after eggshell penetration, C. psittaci could eventually infect the growing embryo. Our findings portend the potential of horizontal trans-shell transmission as a possible route for the spread of C. psittaci infection in poultry flocks. Considering that horizontal transmission of pathogens via eggs mainly occurs in hatcheries and hatching cabinets, we suggest the latter as critical control points in the transmission of C. psittaci to hatching chicks and broilers, as well as to the hatchery workers and consumers of table eggs.

  14. Universal limiting shape of worn profile under multiple-mode fretting conditions: theory and experimental evidence

    PubMed Central

    Dmitriev, Andrey I.; Voll, Lars B.; Psakhie, Sergey G.; Popov, Valentin L.

    2016-01-01

    We consider multiple-mode fretting wear in a frictional contact of elastic bodies subjected to a small-amplitude oscillation, which may include in-plane and out-of-plane translation, torsion and tilting (“periodic rolling”). While the detailed kinetics of wear depends on the particular loading history and wear mechanism, the final worn shape, under some additional conditions, occurs to be universal for all types and loading and wear mechanisms. This universal form is determined solely by the radius of the permanent stick region and the maximum indentation depth during the loading cycle. We provide experimental evidence for the correctness of the theoretically predicted limiting shape. The existence of the universal limiting shape can be used for designing joints which are resistant to fretting wear. PMID:26979092

  15. The scientific consensus on climate change as a gateway belief: experimental evidence.

    PubMed

    van der Linden, Sander L; Leiserowitz, Anthony A; Feinberg, Geoffrey D; Maibach, Edward W

    2015-01-01

    There is currently widespread public misunderstanding about the degree of scientific consensus on human-caused climate change, both in the US as well as internationally. Moreover, previous research has identified important associations between public perceptions of the scientific consensus, belief in climate change and support for climate policy. This paper extends this line of research by advancing and providing experimental evidence for a "gateway belief model" (GBM). Using national data (N = 1104) from a consensus-message experiment, we find that increasing public perceptions of the scientific consensus is significantly and causally associated with an increase in the belief that climate change is happening, human-caused and a worrisome threat. In turn, changes in these key beliefs are predictive of increased support for public action. In short, we find that perceived scientific agreement is an important gateway belief, ultimately influencing public responses to climate change.

  16. Universal limiting shape of worn profile under multiple-mode fretting conditions: theory and experimental evidence

    NASA Astrophysics Data System (ADS)

    Dmitriev, Andrey I.; Voll, Lars B.; Psakhie, Sergey G.; Popov, Valentin L.

    2016-03-01

    We consider multiple-mode fretting wear in a frictional contact of elastic bodies subjected to a small-amplitude oscillation, which may include in-plane and out-of-plane translation, torsion and tilting (“periodic rolling”). While the detailed kinetics of wear depends on the particular loading history and wear mechanism, the final worn shape, under some additional conditions, occurs to be universal for all types and loading and wear mechanisms. This universal form is determined solely by the radius of the permanent stick region and the maximum indentation depth during the loading cycle. We provide experimental evidence for the correctness of the theoretically predicted limiting shape. The existence of the universal limiting shape can be used for designing joints which are resistant to fretting wear.

  17. Individualism, authoritarianism, and attitudes toward assisted death: cross-cultural, cross-regional, and experimental evidence.

    PubMed

    Kemmelmeier, Markus; Wieczorkowska, Grazyna; Erb, Hans-Peter; Burnstein, Eugene

    2002-01-01

    We hypothesized that in individualistic cultures, individualism predicts positive attitudes toward assisted death, whereas authoritarianism is negatively associated with favorable views of this issue. Study 1 confirmed this hypothesis in a Polish sample (n=100). Study 2, using a German sample (n=102), found the predicted relationships for forms of assisted death that involved the individual self-determination of a terminally ill patient. In Study 3 (n=72), we found experimental evidence that priming individualistic aspects of the self-concept results in more favorable views of physician-assisted suicide. Using a representative sample (n=1158), Study 4 found that across the United States, regional levels of individualism are reflected in corresponding patterns of support for assisted suicide. The discussion focuses on assisted suicide as a cultural phenomenon and explores the implications of growing levels of individualism for public opinion and policy on assisted suicide.

  18. Experimental neutron scattering evidence for proton polaron in hydrated metal oxide proton conductors

    NASA Astrophysics Data System (ADS)

    Braun, Artur; Chen, Qianli

    2017-06-01

    Hydration of oxygen-deficient metal oxides causes filling of oxygen vacancies and formation of hydroxyl groups with interstitial structural protons, rotating around the oxygen in localized motion. Thermal activation from 500 to 800 K triggers delocalization of the protons by jumping to adjacent oxygen ions, constituting proton conductivity. We report quantitative analyses of proton and lattice dynamics by neutron-scattering data, which reveal the interaction of protons with the crystal lattice and proton-phonon coupling. The motion for the proton trapped in the elastic crystal field yields Eigen frequencies and coupling constants, which satisfy Holstein's polaron model for electrons and thus constitutes first experimental evidence for a proton polaron at high temperature. Proton jump rates follow a polaron model for cerium-oxygen and hydroxyl stretching modes, which are thus vehicles for proton conductivity. This confirms that the polaron mechanism is not restricted to electrons, but a universal charge carrier transport process.

  19. Behavioural evidence of magnetoreception in dolphins: detection of experimental magnetic fields

    NASA Astrophysics Data System (ADS)

    Kremers, Dorothee; López Marulanda, Juliana; Hausberger, Martine; Lemasson, Alban

    2014-11-01

    Magnetoreception, meaning the perception of magnetic fields, is supposed to play an important role for orientation/navigation in some terrestrial and aquatic species. Although some spatial observations of free-ranging cetaceans' migration routes and stranding sites led to the assumption that cetaceans may be sensitive to the geomagnetic field, experimental evidence is lacking. Here, we tested the spontaneous response of six captive bottlenose dolphins to the presentation of two magnetized and demagnetized controlled devices while they were swimming freely. Dolphins approached the device with shorter latency when it contained a strongly magnetized neodymium block compared to a control demagnetized block that was identical in form and density and therefore undistinguishable with echolocation. We conclude that dolphins are able to discriminate the two stimuli on the basis of their magnetic properties, a prerequisite for magnetoreception-based navigation.

  20. Pediatric asthma case management: a review of evidence and an experimental study design.

    PubMed

    Schulte, Amanda; Musolf, Jeanne; Meurer, John R; Cohn, Jennifer H; Kelly, Kevin J

    2004-08-01

    Asthma is a complex disease that involves physiological, environmental, and psychosocial factors. This paper reviews childhood asthma case management by social service professionals, lay health workers, and nurses, and it presents a new randomized controlled study using nurse case management in a local community coalition. Evidence suggests the common factor for success involves case managers spending time contacting and patiently and persistently working with the family, thus building a trusting relationship. Although case management time is an expense for a health care payer, provider, and the child and family, the positive outcomes achieved can demonstrate the benefit of these interventions to all parties involved. The described experimental study assesses the cost and effectiveness of home-based nurse case management by a community coalition for children visiting an emergency department for asthma care.

  1. Experimental evidence of symmetry-breaking supercritical transition in pipe flow of shear-thinning fluids

    NASA Astrophysics Data System (ADS)

    Wen, Chaofan; Poole, Robert J.; Willis, Ashley P.; Dennis, David J. C.

    2017-03-01

    Experimental results reveal that the asymmetric flow of shear-thinning fluid through a cylindrical pipe, which was previously associated with the laminar-turbulent transition process, appears to have the characteristics of a nonhysteretic, supercritical instability of the laminar base state. Contrary to what was previously believed, classical transition is found to be responsible for returning symmetry to the flow. An absence of evidence of the instability in simulations (either linear or nonlinear) suggests that an element of physics is lacking in the commonly used rheological model for inelastic shear-thinning fluids. These unexpected discoveries raise new questions regarding the stability of these practically important fluids and how they can be successfully modeled.

  2. Speciation in caves: experimental evidence that permanent darkness promotes reproductive isolation

    PubMed Central

    Riesch, Rüdiger; Plath, Martin; Schlupp, Ingo

    2011-01-01

    Divergent selection through biotic factors like predation or parasitism can promote reproductive isolation even in the absence of geographical barriers. On the other hand, evidence for a role of adaptation to abiotic factors during ecological speciation in animals is scant. In particular, the role played by perpetual darkness in establishing reproductive isolation in cave animals (troglobites) remains elusive. We focused on two reproductively isolated ecotypes (surface- and cave-dwelling) of the widespread livebearer Poecilia mexicana, and raised offspring of wild-caught females to sexual maturity in a 12-month common-garden experiment. Fish were reared in light or darkness combined with high- or low-food conditions. Females, but not males, of the surface ecotype suffered from almost complete reproductive failure in darkness, especially in the low-food treatment. Furthermore, surface fish suffered from a significantly higher rate of spontaneous, stress-related infection with bacterial columnaris disease. This experimental evidence for strong selection by permanent darkness on non-adapted surface-dwelling animals adds depth to our understanding of the selective forces establishing and maintaining reproductive isolation in cave faunas. PMID:21561964

  3. Speciation in caves: experimental evidence that permanent darkness promotes reproductive isolation.

    PubMed

    Riesch, Rüdiger; Plath, Martin; Schlupp, Ingo

    2011-12-23

    Divergent selection through biotic factors like predation or parasitism can promote reproductive isolation even in the absence of geographical barriers. On the other hand, evidence for a role of adaptation to abiotic factors during ecological speciation in animals is scant. In particular, the role played by perpetual darkness in establishing reproductive isolation in cave animals (troglobites) remains elusive. We focused on two reproductively isolated ecotypes (surface- and cave-dwelling) of the widespread livebearer Poecilia mexicana, and raised offspring of wild-caught females to sexual maturity in a 12-month common-garden experiment. Fish were reared in light or darkness combined with high- or low-food conditions. Females, but not males, of the surface ecotype suffered from almost complete reproductive failure in darkness, especially in the low-food treatment. Furthermore, surface fish suffered from a significantly higher rate of spontaneous, stress-related infection with bacterial columnaris disease. This experimental evidence for strong selection by permanent darkness on non-adapted surface-dwelling animals adds depth to our understanding of the selective forces establishing and maintaining reproductive isolation in cave faunas.

  4. The impact of energy, agriculture, macroeconomic and human-induced indicators on environmental pollution: evidence from Ghana.

    PubMed

    Asumadu-Sarkodie, Samuel; Owusu, Phebe Asantewaa

    2017-01-12

    In this study, the impact of energy, agriculture, macroeconomic and human-induced indicators on environmental pollution from 1971 to 2011 is investigated using the statistically inspired modification of partial least squares (SIMPLS) regression model. There was evidence of a linear relationship between energy, agriculture, macroeconomic and human-induced indicators and carbon dioxide emissions. Evidence from the SIMPLS regression shows that a 1% increase in crop production index will reduce carbon dioxide emissions by 0.71%. Economic growth increased by 1% will reduce carbon dioxide emissions by 0.46%, which means that an increase in Ghana's economic growth may lead to a reduction in environmental pollution. The increase in electricity production from hydroelectric sources by 1% will reduce carbon dioxide emissions by 0.30%; thus, increasing renewable energy sources in Ghana's energy portfolio will help mitigate carbon dioxide emissions. Increasing enteric emissions by 1% will increase carbon dioxide emissions by 4.22%, and a 1% increase in the nitrogen content of manure management will increase carbon dioxide emissions by 6.69%. The SIMPLS regression forecasting exhibited a 5% MAPE from the prediction of carbon dioxide emissions.

  5. In-Situ and Experimental Evidence for Acidic Weathering of Rocks and Soils on Mars

    NASA Technical Reports Server (NTRS)

    Hurowitz, J. A.; McLennan, S. M.; Tosca, N. J.; Arvidson, R. E.; Michalski, J. R.; Ming, D.; Schroeder, C.; Squyres, S. W.

    2006-01-01

    Experimental data for alteration of synthetic Martian basalts at pH=0-1 indicate that chemical fractionations at low pH are vastly different from those observed during terrestrial weathering. Rock analyses from Gusev crater are well described by the relationships apparent from low pH experimental alteration data. A model for rock surface alteration is developed which indicates that a leached alteration zone is present on rock surfaces at Gusev. This zone is not chemically fractionated to a large degree from the underlying rock interior, indicating that the rock surface alteration process has occurred at low fluid-to-rock ratio. The geochemistry of natural rock surfaces analyzed by APXS is consistent with a mixture between adhering soil/dust and the leached alteration zone. The chemistry of rock surfaces analyzed after brushing with the RAT is largely representative of the leached alteration zone. The chemistry of rock surfaces analyzed after grinding with the RAT is largely representative of the interior of the rock, relatively unaffected by the alteration process occurring at the rock surface. Elemental measurements from the Spirit, Opportunity, Pathfinder and Viking 1 landing sites indicate that soil chemistry from widely separated locations is consistent with the low-pH, low fluid to rock ratio alteration relationships developed for Gusev rocks. Soils are affected principally by mobility of FeO and MgO, consistent with alteration of olivine-bearing basalt and subsequent precipitation of FeO and MgO bearing secondary minerals as the primary control on soil geochemistry.

  6. Experimental evidence of space charge driven resonances in high intensity linear accelerators

    DOE PAGES

    Jeon, Dong -O

    2016-01-12

    In the construction of high intensity accelerators, it is the utmost goal to minimize the beam loss by avoiding or minimizing contributions of various halo formation mechanisms. As a halo formation mechanism, space charge driven resonances are well known for circular accelerators. However, the recent finding showed that even in linear accelerators the space charge potential can excite the 4σ = 360° fourth order resonance [D. Jeon et al., Phys. Rev. ST Accel. Beams 12, 054204 (2009)]. This study increased the interests in space charge driven resonances of linear accelerators. Experimental studies of the space charge driven resonances of highmore » intensity linear accelerators are rare as opposed to the multitude of simulation studies. This paper presents an experimental evidence of the space charge driven 4σ ¼ 360° resonance and the 2σx(y) – 2σz = 0 resonance of a high intensity linear accelerator through beam profile measurements from multiple wire-scanners. Moreover, measured beam profiles agree well with the characteristics of the space charge driven 4σ = 360° resonance and the 2σx(y) – 2σz = 0 resonance that are predicted by the simulation.« less

  7. Experimental evidence of space charge driven resonances in high intensity linear accelerators

    NASA Astrophysics Data System (ADS)

    Jeon, Dong-O.

    2016-01-01

    In the construction of high intensity accelerators, it is the utmost goal to minimize the beam loss by avoiding or minimizing contributions of various halo formation mechanisms. As a halo formation mechanism, space charge driven resonances are well known for circular accelerators. However, the recent finding showed that even in linear accelerators the space charge potential can excite the 4 σ =360 ° fourth order resonance [D. Jeon et al., Phys. Rev. ST Accel. Beams 12, 054204 (2009)]. This study increased the interests in space charge driven resonances of linear accelerators. Experimental studies of the space charge driven resonances of high intensity linear accelerators are rare as opposed to the multitude of simulation studies. This paper presents an experimental evidence of the space charge driven 4 σ =360 ° resonance and the 2 σx (y )-2 σz=0 resonance of a high intensity linear accelerator through beam profile measurements from multiple wire-scanners. Measured beam profiles agree well with the characteristics of the space charge driven 4 σ =360 ° resonance and the 2 σx (y )-2 σz=0 resonance that are predicted by the simulation.

  8. Experimental evidence of Alfvén wave propagation in a Gallium alloy

    NASA Astrophysics Data System (ADS)

    Alboussière, Thierry; Cardin, Philippe; Debray, François; La Rizza, Patrick; Masson, Jean-Paul; Plunian, Franck; Ribeiro, Adolfo; Schmitt, Denys

    2011-09-01

    Experiments with a liquid metal alloy, Galinstan, are reported and show clear evidence of Alfvén wave propagation as well as resonance of Alfvén modes. Galinstan is liquid at room temperature and, although its electrical conductivity is not as large as that of liquid sodium or NaK, it has still been possible to study Alfvén waves, thanks to the use of intense magnetic fields up to 13 T. The maximal values of Lundquist number, around 60, are similar to that of the reference experimental study by Jameson [J. Fluid Mech. 19, 513 (1964)]. The generation mechanism for Alfvén waves and their reflection is studied carefully. Numerical simulations have been performed and have been able to reproduce the experimental results, despite the fact that the simulated magnetic Prandtl number was much larger than that of Galinstan. An originality of the present study is that a poloidal disturbance (magnetic and velocity fields) is generated, allowing us to track its propagation from outside the conducting domain, hence without interfering.

  9. Key experimental evidence of chromosomal DNA transfer among selected tuberculosis-causing mycobacteria

    PubMed Central

    Boritsch, Eva C.; Khanna, Varun; Pawlik, Alexandre; Honoré, Nadine; Navas, Victor H.; Ma, Laurence; Bouchier, Christiane; Supply, Philip

    2016-01-01

    Horizontal gene transfer (HGT) is a major driving force of bacterial diversification and evolution. For tuberculosis-causing mycobacteria, the impact of HGT in the emergence and distribution of dominant lineages remains a matter of debate. Here, by using fluorescence-assisted mating assays and whole genome sequencing, we present unique experimental evidence of chromosomal DNA transfer between tubercle bacilli of the early-branching Mycobacterium canettii clade. We found that the obtained recombinants had received multiple donor-derived DNA fragments in the size range of 100 bp to 118 kbp, fragments large enough to contain whole operons. Although the transfer frequency between M. canettii strains was low and no transfer could be observed among classical Mycobacterium tuberculosis complex (MTBC) strains, our study provides the proof of concept for genetic exchange in tubercle bacilli. This outstanding, now experimentally validated phenomenon presumably played a key role in the early evolution of the MTBC toward pathogenicity. Moreover, our findings also provide important information for the risk evaluation of potential transfer of drug resistance and fitness mutations among clinically relevant mycobacterial strains. PMID:27528665

  10. Lightning injury as a blast injury of skull, brain, and visceral lesions: clinical and experimental evidences.

    PubMed

    Ohashi, M; Hosoda, Y; Fujishiro, Y; Tuyuki, A; Kikuchi, K; Obara, H; Kitagawa, N; Ishikawa, T

    2001-12-01

    The present study attempts to better understand the mechanism of injuries associated with direct lightning strikes. We reviewed the records of 256 individuals struck by lightning between 1965 and 1999, including 56 people who were killed. Basal skull fracture, intracranial haemorrhage, pulmonary haemorrhage, or solid organ rupture was suspected in three men who died. Generally these lesions have been attributed to current flow or falling after being struck. However, examination of surface injuries sustained suggested that the true cause was concussion secondary to blast injury resulting from vaporization of water on the body surface by a surface flashover spark. To investigate this hypothesis, an experimental model of a lightning strike was created in the rat. Saline-soaked blotting paper was used to simulate wet clothing or skin, and an artificial lightning impulse was applied. The resultant lesions were consistent with our hypothesis that the blast was reinforced by the concussive effect of water vaporization. The concordance between the clinical and experimental evidence argues strongly for blast injury as an important source of morbidity and mortality in lightning strikes.

  11. Experimental evidence for melt partitioning between olivine and orthopyroxene in partially molten harzburgite

    NASA Astrophysics Data System (ADS)

    Miller, Kevin J.; Zhu, Wen-lu; Montési, Laurent G. J.; Gaetani, Glenn A.; Le Roux, Véronique; Xiao, Xianghui

    2016-08-01

    Observations of dunite channels in ophiolites and uranium series disequilibria in mid-ocean ridge basalt suggest that melt transport in the upper mantle beneath mid-ocean ridges is strongly channelized. We present experimental evidence that spatial variations in mineralogy can also focus melt on the grain scale. This lithologic melt partitioning, which results from differences in the interfacial energies associated with olivine-melt and orthopyroxene-melt boundaries, may complement other melt focusing mechanisms in the upper mantle such as mechanical shear and pyroxene dissolution. We document here lithologic melt partitioning in olivine-/orthopyroxene-basaltic melt samples containing nominal olivine to orthopyroxene ratio of 3 to 2 and melt fractions of 0.02 to 0.20. Experimental samples were imaged using synchrotron-based X-ray microcomputed tomography at a resolution of 700 nm per voxel. By analyzing the local melt fraction distributions associated with olivine and orthopyroxene grains in each sample, we found that the melt partitioning coefficient, i.e., the ratio of melt fraction around olivine to that around orthopyroxene grains, varies between 1.1 and 1.6. The permeability and electrical conductivity of our digital samples were estimated using numerical models and compared to those of samples containing only olivine and basaltic melt. Our results suggest that lithologic melt partitioning and preferential localization of melt around olivine grains might play a role in melt focusing, potentially enhancing average melt ascent velocities.

  12. Role of Chronic Inflammation in Myopia Progression: Clinical Evidence and Experimental Validation.

    PubMed

    Lin, Hui-Ju; Wei, Chang-Ching; Chang, Ching-Yao; Chen, Ter-Hsin; Hsu, Yu-An; Hsieh, Yi-Ching; Chen, Hsuan-Ju; Wan, Lei

    2016-08-01

    Prevention and treatment of myopia is an important public problem worldwide. We found a higher incidence of myopia among patients with inflammatory diseases such as type 1 diabetes mellitus (7.9%), uveitis (3.7%), or systemic lupus erythematosus (3.5%) compared to those without inflammatory diseases (p<0.001) using data from children (<18years old) in the National Health Insurance Research database. We then examined the inhibition of myopia by atropine in Syrian hamsters with monocular form deprivation (MFD), an experimental myopia model. We found atropine downregulated inflammation in MFD eyes. The expression levels of c-Fos, nuclear factor κB (NFκB), interleukin (IL)-6, and tumor necrosis factor (TNF)-α were upregulated in myopic eyes and downregulated upon treatment with atropine. The relationship between the inflammatory response and myopia was investigated by treating MFD hamsters with the immunosuppressive agent cyclosporine A (CSA) or the inflammatory stimulators lipopolysaccharide (LPS) or peptidoglycan (PGN). Myopia progression was slowed by CSA application but was enhanced by LPS and PGN administration. The levels of c-Fos, NF-κB, IL-6, and TNF-α were upregulated in LPS- and PGN-treated eyes and downregulated by CSA treatment. These findings provide clinical and experimental evidence that inflammation plays a crucial role in the development of myopia. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  13. Experimental and observational evidence for plume-induced subduction on Venus

    NASA Astrophysics Data System (ADS)

    Davaille, A.; Smrekar, S. E.; Tomlinson, S.

    2017-04-01

    Why Venus lacks plate tectonics remains an unanswered question in terrestrial planet evolution. There is observational evidence for subduction--a requirement for plate tectonics--on Venus, but it is unclear why the features have characteristics of both mantle plumes and subduction zones. One explanation is that mantle plumes trigger subduction. Here we compare laboratory experiments of plume-induced subduction in a colloidal solution of nanoparticles to observations of proposed subduction sites on Venus. The experimental fluids are heated from below to produce upwelling plumes, which in turn produce tensile fractures in the lithosphere-like skin that forms on the upper surface. Plume material upwells through the fractures and spreads above the skin, analogous to volcanic flooding, and leads to bending and eventual subduction of the skin along arcuate segments. The segments are analogous to the semi-circular trenches seen at two proposed sites of plume-triggered subduction at Quetzalpetlatl and Artemis coronae. Other experimental deformation structures and subsurface density variations are also consistent with topography, radar and gravity data for Venus. Scaling analysis suggests that this regime with limited, plume-induced subduction is favoured by a hot lithosphere, such as that found on early Earth or present-day Venus.

  14. State-dependent alpha peak frequency shifts: Experimental evidence, potential mechanisms and functional implications.

    PubMed

    Mierau, Andreas; Klimesch, Wolfgang; Lefebvre, Jérémie

    2017-09-30

    Neural populations produce complex oscillatory patterns thought to implement brain function. The dominant rhythm in the healthy adult human brain is formed by alpha oscillations with a typical power peak most commonly found between 8 and 12Hz. This alpha peak frequency has been repeatedly discussed as a highly heritable and stable neurophysiological "trait" marker reflecting anatomical properties of the brain, and individuals' general cognitive capacity. However, growing evidence suggests that the alpha peak frequency is highly volatile at shorter time scales, dependent on the individuals' "state". Based on the converging experimental and theoretical results from numerous recent studies, here we propose that alpha frequency variability forms the basis of an adaptive mechanism mirroring the activation level of neural populations which has important functional implications. We here integrate experimental and computational perspectives to shed new light on the potential role played by shifts in alpha peak frequency and discuss resulting implications. We further propose a potential mechanism by which alpha oscillations are regulated in a noisy network of spiking neurons in presence of delayed feedback. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Experimental evidence validating the computational inference of functional associations from gene fusion events: a critical survey.

    PubMed

    Promponas, Vasilis J; Ouzounis, Christos A; Iliopoulos, Ioannis

    2014-05-01

    More than a decade ago, a number of methods were proposed for the inference of protein interactions, using whole-genome information from gene clusters, gene fusions and phylogenetic profiles. This structural and evolutionary view of entire genomes has provided a valuable approach for the functional characterization of proteins, especially those without sequence similarity to proteins of known function. Furthermore, this view has raised the real possibility to detect functional associations of genes and their corresponding proteins for any entire genome sequence. Yet, despite these exciting developments, there have been relatively few cases of real use of these methods outside the computational biology field, as reflected from citation analysis. These methods have the potential to be used in high-throughput experimental settings in functional genomics and proteomics to validate results with very high accuracy and good coverage. In this critical survey, we provide a comprehensive overview of 30 most prominent examples of single pairwise protein interaction cases in small-scale studies, where protein interactions have either been detected by gene fusion or yielded additional, corroborating evidence from biochemical observations. Our conclusion is that with the derivation of a validated gold-standard corpus and better data integration with big experiments, gene fusion detection can truly become a valuable tool for large-scale experimental biology.

  16. Experimental evidence for the evolution of the Mammalian baculum by sexual selection.

    PubMed

    Simmons, Leigh W; Firman, Renée C

    2014-01-01

    Male genitalia exhibit a taxonomically widespread pattern of rapid and divergent evolution. Sexual selection is generally believed to be responsible for these patterns of evolutionary divergence, although empirical support for the sexual selection hypothesis comes mainly from studies of insects. Here we show that sexual selection is responsible for an evolutionary divergence in baculum morphology among populations of house mice Mus domesticus. We sourced mice from three isolated populations known to be subject to differing strengths of postcopulatory sexual selection and bred them under common-garden conditions. Mice from populations with strong postcopulatory sexual selection had bacula that were relatively thicker compared with mice from populations with weak selection. We used experimental evolution to determine whether these patterns of divergence could be ascribed to postcopulatory sexual selection. After 27 generations of experimental evolution, populations of mice subjected to postcopulatory sexual selection evolved bacula that were relatively thicker than populations subjected to enforced monogamy. Our data thereby provide evidence that postcopulatory sexual selection underlies an evolutionary divergence in the mammalian baculum and supports the hypothesis that sexual selection plays a general role in the evolution of male genital morphology across evolutionary diverse taxonomic groups. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

  17. The relationship between malnutrition and tuberculosis: evidence from studies in humans and experimental animals.

    PubMed

    Cegielski, J P; McMurray, D N

    2004-03-01

    The oral traditions of medicine and public health have it that malnutrition is an important risk factor for the development of tuberculosis (TB). Malnutrition profoundly affects cell-mediated immunity (CMI), and CMI is the principle host defense against TB. It makes biological sense. Although most health professionals readily accept this principle, much of this belief is based on uncontrolled observations such as disaster situations or on backwards logic from the cachexia common among TB patients. In fact, the evidence in humans is surprisingly thin from the perspective of scientific rigor. And few data, if any, quantify the extent of the relative or attributable risk of TB due to malnutrition. Moreover, until recently, data from experimental animals were based on animal models that were largely not relevant to human TB infection and disease. This article reviews the scientific data supporting the contention that malnutrition is an important risk factor for TB concentrating on observations in humans and on experimental animal studies based on a highly relevant animal model. If it is true, malnutrition may account for a greater population attributable risk of TB than HIV infection, and certainly a much more correctable one.

  18. Renin Angiotensin System and cytokines in chronic kidney disease: Clinical and experimental evidence.

    PubMed

    Silva, Ariadna Andrade Saldanha; Finotti, Beranardo Bahia; Lauar, Amanda Oliveira; Prestes, Thiago Ruiz Rodrigues; Silva, Ana Cristina Simões E

    2017-08-18

    Chronic kidney disease (CKD) has become a major public health problem in Brazil and worldwide. There are many causes of CKD, being the congenital anomalies of the kidney and urinary tract and the glomerular diseases very common in pediatric patients, while diabetic nephropathy, CKD due to chronic arterial hypertension and glomerular diseases are predominant in adult patients. Many endogenous mediators have been related to the pathophysiology of CKD, being relevant the effects of the renin-angiotensin system (RAS) and the immune-inflammatory mediators including cytokines. Several experimental and clinical studies have shown the role of the cytokines and RAS peptides in the pathophysiology of CKD. The blockade of the classical RAS axis, comprising angiotensin converting enzyme (ACE), the octapeptide Angiotensin II and the angiotensin type 1 (AT1) receptor, delays the development of CKD through multiple mechanisms, including the control of inflammatory response mediated by cytokines. On the other hand, the counterregulatory RAS axis, formed by the enzyme homologue to ACE named ACE2, the heptapeptide Angiotensin-(1-7) and its G-protein coupled receptor, the receptor Mas, exerts several renoprotective actions, mostly related to the inhibition of renal tissue inflammation and fibrosis. This review aims to report clinical and experimental evidence of the interaction between both RAS axes and cytokines in the pathophysiology of CKD. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  19. The glycaemic outcomes of Cinnamon, a review of the experimental evidence and clinical trials.

    PubMed

    Medagama, Arjuna B

    2015-10-16

    Cinnamon is currently marketed as a remedy for obesity, glucose intolerance, diabetes mellitus and dyslipidaemia. Integrative medicine is a new concept that combines conventional treatment with evidence-based complementary therapies. The aim of this review is to critically evaluate the experimental evidence available for cinnamon in improving glycaemic targets in animal models and humans. Insulin receptor auto-phosphorlylation and de-phosphorylation, glucose transporter 4 (GLUT-4 ) receptor synthesis and translocation, modulation of hepatic glucose metabolism through changes in Pyruvate kinase (PK) and Phosphenol Pyruvate Carboxikinase (PEPCK), altering the expression of PPAR (γ) and inhibition of intestinal glucosidases are some of the mechanisms responsible for improving glycaemic control with cinnamon therapy. We reviewed 8 clinical trials that used Cinnamomum cassia in aqueous or powder form in doses ranging from 500 mg to 6 g per day for a duration lasting from 40 days to 4 months as well as 2 clinical trials that used cinnamon on treatment naïve patients with pre-diabetes. An improvement in glycaemic control was seen in patients who received Cinnamon as the sole therapy for diabetes, those with pre-diabetes (IFG or IGT) and in those with high pre-treatment HbA1c. In animal models, cinnamon reduced fasting and postprandial plasma glucose and HbA1c. Cinnamon has the potential to be a useful add-on therapy in the discipline of integrative medicine in managing type 2 diabetes. At present the evidence is inconclusive and long-term trials aiming to establish the efficacy and safety of cinnamon is needed. However, high coumarin content of Cinnamomum cassia is a concern, but Cinnamomum zeylanicum with its low coumarin content would be a safer alternate.

  20. Astragaloside IV for Experimental Focal Cerebral Ischemia: Preclinical Evidence and Possible Mechanisms

    PubMed Central

    Wang, Hui-Lin; Zhou, Qi-Hui; Xu, Meng-Bei; Zhou, Xiao-Li

    2017-01-01

    Astragaloside IV (AST-IV) is a principal component of Radix Astragali seu Hedysari (Huangqi) and exerts potential neuroprotection in experimental ischemic stroke. Here, we systematically assessed the effectiveness and possible mechanisms of AST-IV for experimental acute ischemic stroke. An electronic search in eight databases was conducted from inception to March 2016. The study quality score was evaluated using the CAMARADES. Rev Man 5.0 software was used for data analyses. Thirteen studies with 244 animals were identified. The study quality score of included studies ranged from 3/10 to 8/10. Eleven studies showed significant effects of AST-IV for ameliorating the neurological function score (P < 0.05); seven studies for reducing the infarct volume (P < 0.05); and three or two studies for reducing the brain water content and Evans blue leakage (P < 0.05), respectively, compared with the control. The mechanisms of AST-IV for ischemic stroke are multiple such as antioxidative/nitration stress reaction, anti-inflammatory, and antiapoptosis. In conclusion, the findings of present study indicated that AST-IV could improve neurological deficits and infarct volume and reduce the blood-brain barrier permeability in experimental cerebral ischemia despite some methodological flaws. Thus, AST-IV exerted a possible neuroprotective effect during the cerebral ischemia/reperfusion injury largely through its antioxidant, anti-inflammatory, and antiapoptosis properties. PMID:28303172

  1. Impact of SOL plasma profiles on lower hybrid current drive: Experimental evidence, mitigation and modeling approaches

    NASA Astrophysics Data System (ADS)

    Shiraiwa, S.; Baek, S. G.; Faust, I.; Wallace, G.; Bonoli, P.; Meneghini, O.; Mumgaard, R.; Parker, R.; Scott, S.; Harvey, R. W.; Ding, B. J.; Li, M. H.; Lin, S. Y.; Yang, C.

    2015-12-01

    Recent progress in understanding and mitigating parasitic wave absorption in edge plasmas is presented. Experimental observations collected on Alcator C-Mod suggest multiple physics mechanisms are involved in such losses. Localized measurement of parametric decay instabilities (PDIs) has been performed using RF Langmuir probes. The divertor heat flux due to LH and ionization power loss have been evaluated quantitatively. We observe that the LHCD efficiency can be recovered when the SOL density profile is controlled by operating the tokamak at high current. The experimental progresses motivated a re-examination of the LHCD simulation model based on the ray-tracing/Fokker-Planck code (GENRAY/CQL3D). The effect of introducing a relatively small wave number broadening in the launched power spectrum and using 2D SOL density and temperature profiles was investigated. Comparison with C-Mod experiment indicates that the new model can explain the experimental trend over a wider density range including the density regime where disagreement was seen previously, suggesting that including realistic SOL geometry is a key to improve the simulation accuracy.

  2. A novel transmembrane topology of presenilin based on reconciling experimental and computational evidence.

    PubMed

    Henricson, Anna; Käll, Lukas; Sonnhammer, Erik L L

    2005-06-01

    The transmembrane topology of presenilins is still the subject of debate despite many experimental topology studies using antibodies or gene fusions. The results from these studies are partly contradictory and consequently several topology models have been proposed. Studies of presenilin-interacting proteins have produced further contradiction, primarily regarding the location of the C-terminus. It is thus impossible to produce a topology model that agrees with all published data on presenilin. We have analyzed the presenilin topology through computational sequence analysis of the presenilin family and the homologous presenilin-like protein family. Members of these families are intramembrane-cleaving aspartyl proteases. Although the overall sequence homology between the two families is low, they share the conserved putative active site residues and the conserved 'PAL' motif. Therefore, the topology model for the presenilin-like proteins can give some clues about the presenilin topology. Here we propose a novel nine-transmembrane topology with the C-terminus in the extracytosolic space. This model has strong support from published data on gamma-secretase function and presenilin topology. Contrary to most presenilin topology models, we show that hydrophobic region X is probably a transmembrane segment. Consequently, the C-terminus would be located in the extracytosolic space. However, the last C-terminal amino acids are relatively hydrophobic and in conjunction with existing experimental data we cannot exclude the possibility that the extreme C-terminus could be buried within the gamma-secretase complex. This might explain the difficulties in obtaining consistent experimental evidence regarding the location of the C-terminal region of presenilin.

  3. How experimental biology and ecology can support evidence-based decision-making in conservation: avoiding pitfalls and enabling application

    PubMed Central

    Birnie-Gauvin, Kim; Lennox, Robert J.; Taylor, Jessica J.; Rytwinski, Trina; Rummer, Jodie L.; Franklin, Craig E.; Bennett, Joseph R.; Haddaway, Neal R.

    2017-01-01

    Abstract Policy development and management decisions should be based upon the best available evidence. In recent years, approaches to evidence synthesis, originating in the medical realm (such as systematic reviews), have been applied to conservation to promote evidence-based conservation and environmental management. Systematic reviews involve a critical appraisal of evidence, but studies that lack the necessary rigour (e.g. experimental, technical and analytical aspects) to justify their conclusions are typically excluded from systematic reviews or down-weighted in terms of their influence. One of the strengths of conservation physiology is the reliance on experimental approaches that help to more clearly establish cause-and-effect relationships. Indeed, experimental biology and ecology have much to offer in terms of building the evidence base that is needed to inform policy and management options related to pressing issues such as enacting endangered species recovery plans or evaluating the effectiveness of conservation interventions. Here, we identify a number of pitfalls that can prevent experimental findings from being relevant to conservation or would lead to their exclusion or down-weighting during critical appraisal in a systematic review. We conclude that conservation physiology is well positioned to support evidence-based conservation, provided that experimental designs are robust and that conservation physiologists understand the nuances associated with informing decision-making processes so that they can be more relevant. PMID:28835842

  4. Experimental evidence that livestock grazing intensity affects the activity of a generalist predator

    NASA Astrophysics Data System (ADS)

    Villar, Nacho; Lambin, Xavier; Evans, Darren; Pakeman, Robin; Redpath, Steve

    2013-05-01

    Grazing by domestic ungulates has substantial impacts on ecosystem structure and composition. In grasslands of the northern hemisphere, livestock grazing limits populations of small mammals, which are a main food source for a variety of vertebrate predators. However, no experimental studies have described the impact of livestock grazing on vertebrate predators. We experimentally manipulated sheep and cattle grazing intensity in the Scottish uplands to test its impact on a relatively abundant small mammal, the field vole (Microtus agrestis), and its archetypal generalist predator, the red fox (Vulpes vulpes). We demonstrate that ungulate grazing had a strong consistent negative impact on both vole densities and indices of fox activity. Ungulate grazing did not substantially affect the relationship between fox activity and vole densities. However, the data suggested that, as grazing intensity increased i) fox activity indices tended to be higher when vole densities were low, and ii) the relationship between fox activity and vole density was weaker. All these patterns are surprising given the relative small scale of our experiment compared to large red fox territories in upland habitats of Britain, and suggest that domestic grazing intensity causes a strong response in the activity of generalist predators important for their conservation in grassland ecosystems.

  5. The role of barrier membranes for guided bone regeneration and restoration of large bone defects: current experimental and clinical evidence.

    PubMed

    Dimitriou, Rozalia; Mataliotakis, George I; Calori, Giorgio Maria; Giannoudis, Peter V

    2012-07-26

    Treatment of large bone defects represents a great challenge in orthopedic and craniomaxillofacial surgery. Although there are several methods for bone reconstruction, they all have specific indications and limitations. The concept of using barrier membranes for restoration of bone defects has been developed in an effort to simplify their treatment by offering a single-staged procedure. Research on this field of bone regeneration is ongoing, with evidence being mainly attained from preclinical studies. The purpose of this review is to summarize the current experimental and clinical evidence on the use of barrier membranes for restoration of bone defects in maxillofacial and orthopedic surgery. Although there are a few promising preliminary human studies, before clinical applications can be recommended, future research should aim to establish the 'ideal' barrier membrane and delineate the need for additional bone grafting materials aiming to 'mimic' or even accelerate the normal process of bone formation. Reproducible results and long-term observations with barrier membranes in animal studies, and particularly in large animal models, are required as well as well-designed clinical studies to evaluate their safety, efficacy and cost-effectiveness.

  6. The role of barrier membranes for guided bone regeneration and restoration of large bone defects: current experimental and clinical evidence

    PubMed Central

    2012-01-01

    Treatment of large bone defects represents a great challenge in orthopedic and craniomaxillofacial surgery. Although there are several methods for bone reconstruction, they all have specific indications and limitations. The concept of using barrier membranes for restoration of bone defects has been developed in an effort to simplify their treatment by offering a sinlge-staged procedure. Research on this field of bone regeneration is ongoing, with evidence being mainly attained from preclinical studies. The purpose of this review is to summarize the current experimental and clinical evidence on the use of barrier membranes for restoration of bone defects in maxillofacial and orthopedic surgery. Although there are a few promising preliminary human studies, before clinical applications can be recommended, future research should aim to establish the 'ideal' barrier membrane and delineate the need for additional bone grafting materials aiming to 'mimic' or even accelerate the normal process of bone formation. Reproducible results and long-term observations with barrier membranes in animal studies, and particularly in large animal models, are required as well as well-designed clinical studies to evaluate their safety, efficacy and cost-effectiveness. PMID:22834465

  7. Motivating blood donors to recruit new donors: experimental evaluation of an evidence-based behavior change intervention.

    PubMed

    Lemmens, Karin P H; Ruiter, Robert A C; Abraham, Charles; Veldhuizen, Ingrid J T; Schaalma, Herman P

    2010-11-01

    A sustainable, evidence-based intervention to motivate current blood donors to recruit new donors was evaluated using a quasi-experimental, in-service trial at three donation centers. Participating blood donors in three conditions (N = 734), received (1) an evidence-based leaflet designed to enhance recruitment motivation and five postcards facilitating recruitment and donor registration, (2) five postcards alone, or (3) no materials. Self-reported donor recruitment by donors was measured at 1-week and 6-week follow-up. At 1-week and at 6-week follow-up, donors in both intervention conditions reported talking to more people about donation and asking more people to donate than control participants. Intervention participants also reported persuading more people to register as a donor than control participants. Results indicated that postcards plus leaflet was somewhat more effective than the postcards alone. Donors' intentions to recruit at 1-week follow-up mediated the behavioral effects at 6-week follow-up. Motivating and facilitating recruitment of new blood donors through existing donors has the potential to continually replenish the donor population. © 2010 APA, all rights reserved.

  8. Experimental evidence for distinct costs of pathogenesis and immunity against a natural pathogen in a wild bird.

    PubMed

    Bonneaud, Camille; Balenger, Susan L; Hill, Geoffrey E; Russell, Andrew F

    2012-10-01

    Protective immunity is expected to evolve when the costs of mounting an immune response are less than those of harbouring pathogens. Estimating the costs of immunity vs. pathogenesis in natural systems is challenging, however, because they are typically closely linked. Here we attempt to disentangle the relative cost of each using experimental infections in a natural host-parasite system in which hosts (house finches, Carpodacus mexicanus) differ in resistance to a bacterium (Mycoplasma gallisepticum, MG), depending on whether they originate from co-evolved or unexposed populations. Experimental infection with a 2007-strain of MG caused finches from co-evolved populations to lose significantly more mass relative to controls, than those from unexposed populations. In addition, infected co-evolved finches that lost the most mass harboured the least amounts of MG, whereas the reverse was true in finches from unexposed populations. Finally, within co-evolved populations, individuals that displayed transcriptional evidence of higher protective immune activity, as indicated by changes in the expression of candidate immune and immune-related genes in a direction consistent with increased resistance to MG, showed greater mass loss and lower MG load. Thus, mass loss appeared to reflect the costs of immunity vs. pathogenesis in co-evolved and unexposed populations, respectively. Our results suggest that resistance can evolve even when the short-term energetic costs of protective immunity exceed those of pathogenesis, providing the longer-term fitness costs of infection are sufficiently high. © 2012 Blackwell Publishing Ltd.

  9. The relevance of the evolution of experimental studies for the interpretation and evaluation of some trace physical evidence.

    PubMed

    Morgan, R M; Cohen, J; McGookin, I; Murly-Gotto, J; O'Connor, R; Muress, S; Freudiger-Bonzon, J; Bull, P A

    2009-12-01

    In order for trace evidence to have a high evidential value, experimental studies which mimic the forensic reality are of fundamental importance. Such primary level experimentation is crucial to establish a coherent body of theory concerning the generation, transfer and persistence of different forms of trace physical evidence. We contend that the forensic context, at whatever scale, will be specific to each individual forensic case and this context in which a crime takes place will influence the properties of trace evidence. It will, therefore, be necessary in many forensic cases to undertake secondary level experimental studies that incorporate specific variables pertinent to a particular case and supplement the established theory presented in the published literature. Such studies enable a better understanding of the specific forensic context and thus allow more accurate collection, analysis and interpretation of the trace physical evidence to be achieved. This paper presents two cases where the findings of secondary level experimental studies undertaken to address specific issues particular to two forensic investigations proved to be important. Specific pre-, syn- and post-forensic event factors were incorporated into the experimental design and proved to be invaluable in the recovery, analysis and in achieving accurate interpretations of both soil evidence from footwear and glass trace evidence from a broken window. These studies demonstrate that a fuller understanding of the specific context within which trace physical evidence is generated and subsequently collected, as well as an understanding of the behaviour of certain forms of trace physical evidence under specific conditions, can add evidentiary weight to the analysis and interpretation of that evidence and thus help a court with greater certainty where resources (time and cost) permit.

  10. The Effectiveness of Clinically Indicated Replacement of Peripheral Intravenous Catheters: An Evidence Review With Implications for Clinical Practice.

    PubMed

    Morrison, Kimberly; Holt, Karyn E

    2015-08-01

    Current clinical guidelines from the Centers for Disease Control and Prevention (CDC; 2011) state that peripheral intravenous catheters are to be replaced every 72-96 hr to prevent infection and phlebitis in the adult patient. It is unclear whether this practice reduces the incidence of phlebitis or other infections. The aim of this study was to examine levels I and II evidence to determine if replacing peripheral intravenous catheters only when clinically indicated compared to every 72-96 hr increases the adult patient's risk for infection or phlebitis. The following patient or population, intervention, comparison, outcome question was used to search the literature databases PubMed, ClinicalKey, ProQuest, Ovid SP, and CINAHL: In the adult patient requiring a peripheral vascular catheter (P), does replacing the catheter only when clinically indicated (I) compared to replacing the catheter every 72-96 hr (C) increase the occurrence of phlebitis and infection (O)? A set of specific search criteria along with critical appraisal tools was used to identify relative studies. Four level II randomized controlled trials with no less than 155 subjects, and two level I meta-analyses reviewing a total of 13 research studies indicated that the replacement of peripheral intravenous catheters only when clinically indicated does not increase patient risk of phlebitis or infection when compared to the current practice of routine replacement between 72 and 96 hr in the adult patient population. The current practice of replacing peripheral intravenous catheters every 72-96 hr does not decrease the incidence of phlebitis or infection when compared to replacing catheters when clinically indicated in the adult population. By translating this research into current practice, healthcare costs and nursing care time will decrease, and unnecessary invasive procedures would be eliminated thereby increasing patient safety and satisfaction. © 2015 Sigma Theta Tau International.

  11. Simulation-Based Evaluation of PK/PD Indices for Meropenem Across Patient Groups and Experimental Designs.

    PubMed

    Kristoffersson, Anders N; David-Pierson, Pascale; Parrott, Neil J; Kuhlmann, Olaf; Lave, Thierry; Friberg, Lena E; Nielsen, Elisabet I

    2016-05-01

    Antibiotic dose predictions based on PK/PD indices rely on that the index type and magnitude is insensitive to the pharmacokinetics (PK), the dosing regimen, and bacterial susceptibility. In this work we perform simulations to challenge these assumptions for meropenem and Pseudomonas aeruginosa. A published murine dose fractionation study was replicated in silico. The sensitivity of the PK/PD index towards experimental design, drug susceptibility, uncertainty in MIC and different PK profiles was evaluated. The previous murine study data were well replicated with fT > MIC selected as the best predictor. However, for increased dosing frequencies fAUC/MIC was found to be more predictive and the magnitude of the index was sensitive to drug susceptibility. With human PK fT > MIC and fAUC/MIC had similar predictive capacities with preference for fT > MIC when short t1/2 and fAUC/MIC when long t1/2. A longitudinal PKPD model based on in vitro data successfully predicted a previous in vivo study of meropenem. The type and magnitude of the PK/PD index were sensitive to the experimental design, the MIC and the PK. Therefore, it may be preferable to perform simulations for dose selection based on an integrated PK-PKPD model rather than using a fixed PK/PD index target.

  12. A multidisciplinary weight of evidence approach for environmental risk assessment at the Costa Concordia wreck: Integrative indices from Mussel Watch.

    PubMed

    Regoli, Francesco; Pellegrini, David; Cicero, Anna Maria; Nigro, Marco; Benedetti, Maura; Gorbi, Stefania; Fattorini, Daniele; D'Errico, Giuseppe; Di Carlo, Marta; Nardi, Alessandro; Gaion, Andrea; Scuderi, Alice; Giuliani, Silvia; Romanelli, Giulia; Berto, Daniela; Trabucco, Benedetta; Guidi, Patrizia; Bernardeschi, Margherita; Scarcelli, Vittoria; Frenzilli, Giada

    2014-05-01

    A complex framework of chemical, biological and oceanographic activities was immediately activated after the Costa Concordia shipwreck, to assess possible contamination events and the environmental impact during both emergency and wreck removal operations. In the present paper, we describe the results obtained with caged mussels, Mytilus galloprovincialis, chosen as bioindicator organisms to detect variations of bioavailability and the early onset of molecular and cellular effects (biomarkers). Seven translocation experiments were carried out during the first year from the incident, with organisms deployed at 2 depths in 3 different sites. After 4-6 weeks, tissue concentrations were measured for the main classes of potentially released chemicals (trace metals, polycyclic aromatic hydrocarbons, volatile and aliphatic hydrocarbons, polychlorinated biphenyls, halogenated pesticides, organotin compounds, brominated flame retardants, anionic surfactants); a wide battery of biomarkers covered responses indicative of exposure, detoxification, oxidative stress, cell damage and genotoxic effects. Results excluded serious contamination events or a consistent increase of environmental pollution although some episodic spills with reversible effects were detected. Data were elaborated within a quantitative weight of evidence (WOE) model which provided synthetic hazard indices for each typology of data, before their overall integration in an environmental risk index, which generally ranged from slight to moderate. The proposed WOE model was confirmed a useful tool to summarize large datasets of complex data in integrative indices, and to simplify the interpretation for stakeholders and decision makers, thus supporting a more comprehensive process of "site-oriented" management decisions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Geomorphic evidence for former lobate debris aprons at low latitudes on Mars: Indicators of the Martian paleoclimate

    USGS Publications Warehouse

    Hauber, E.; Van Gasselt, S.; Chapman, M.G.; Neukum, G.

    2008-01-01

    Circumferential depressions enclosing mesas and plateaus in the northern Kasei Valles and in the Tartarus Colles regions of Mars are interpreted as indicators of the former extent of lobate debris aprons, thought to be mixtures of ice and elastic particles. These former lobate debris aprons existed about 1 Ga ago and were embayed by lavas or other flow deposits. After the lobate debris aprons had been removed by sublimation and deflation, topographic depressions with a depth of 50 m and a width of several kilometers were left behind between the mesa or plateau scarp and the solidified flow materials. These depressions or moats are located equatorward of ??30?? at significantly lower latitudes than generally observed for occurrences of modem, intact lobate debris aprons. This observation provides evidence that the paleoclimate at that time was different than today, probably due to a higher averaged obliquity of the planet's rotational axis. Copyright 2008 by the American Geophysical Union.

  14. Geomorphic evidence for former lobate debris aprons at low latitudes on Mars: Indicators of the Martian paleoclimate

    NASA Astrophysics Data System (ADS)

    Hauber, E.; van Gasselt, S.; Chapman, M. G.; Neukum, G.

    2008-02-01

    Circumferential depressions enclosing mesas and plateaus in the northern Kasei Valles and in the Tartarus Colles regions of Mars are interpreted as indicators of the former extent of lobate debris aprons, thought to be mixtures of ice and clastic particles. These former lobate debris aprons existed about 1 Ga ago and were embayed by lavas or other flow deposits. After the lobate debris aprons had been removed by sublimation and deflation, topographic depressions with a depth of 50 m and a width of several kilometers were left behind between the mesa or plateau scarp and the solidified flow materials. These depressions or moats are located equatorward of +/-30° at significantly lower latitudes than generally observed for occurrences of modern, intact lobate debris aprons. This observation provides evidence that the paleoclimate at that time was different than today, probably due to a higher averaged obliquity of the planet's rotational axis.

  15. Experimental evidence for the ancestry of allotetraploid Trifolium repens and creation of synthetic forms with value for plant breeding

    PubMed Central

    2012-01-01

    Background White clover (Trifolium repens) is a ubiquitous weed of the temperate world that through use of improved cultivars has also become the most important legume of grazed pastures world-wide. It has long been suspected to be allotetraploid, but the diploid ancestral species have remained elusive. Putative diploid ancestors were indicated by DNA sequence phylogeny to be T. pallescens and T. occidentale. Here, we use further DNA evidence as well as a combination of molecular cytogenetics (FISH and GISH) and experimental hybridization to test the hypothesis that white clover originated as a hybrid between T. pallescens and T. occidentale. Results T. pallescens plants were identified with chloroplast trnL intron DNA sequences identical to those of white clover. Similarly, T. occidentale plants with nuclear ITS sequences identical to white clover were also identified. Reciprocal GISH experiments, alternately using labeled genomic DNA probes from each of the putative ancestral species on the same white clover cells, showed that half of the chromosomes hybridized with each probe. F1 hybrids were generated by embryo rescue and these showed strong interspecific chromosome pairing and produced a significant frequency of unreduced gametes, indicating the likely mode of polyploidization. The F1 hybrids are inter-fertile with white clover and function as synthetic white clovers, a valuable new resource for the re-incorporation of ancestral genomes into modern white clover for future plant breeding. Conclusions Evidence from DNA sequence analyses, molecular cytogenetics, interspecific hybridization and breeding experiments supports the hypothesis that a diploid alpine species (T. pallescens) hybridized with a diploid coastal species (T. occidentale) to generate tetraploid T. repens. The coming together of these two narrowly adapted species (one alpine and the other maritime), along with allotetraploidy, has led to a transgressive hybrid with a broad adaptive range. PMID

  16. Experimental evidence of transport of pesticides through field soils - a review

    SciTech Connect

    Flury, M.

    1996-01-01

    Much information is available in the literature about pesticide transport through soils at the field scale. The purpose of this study is to review the literature with a focus on pesticide leaching to groundwater. The literature was compiled and discussed with respect to different factors that influence pesticide leaching. Pesticide leaching below the root zone has been demonstrated in sandy as well as in loamy soils. Particularly in loamy soils, there is evidence that even strongly adsorbing chemicals can move along preferential flow pathways and that the travel times of pesticides are comparable to those of conservative solutes. The amounts of pesticides leached below the root zone by worst case rainfall events depend on the chemical properties and can reach up to 5% of the applied mass. When there is no heavy rainfall shortly following application of chemicals, the mass annually leached below the root zone is in the range of <0.1 to 1%, occasionally it can reach up to 4%. Although a direct comparison cannot be made, the mass lost by leaching seems generally to be smaller than that lost by runoff, depending of course on the slope of the fields. Several factors that affect pesticide leaching, such as surface preparation, soil structure, soil water content, type of irrigation, pesticide formulation, time of application and rainfall events, are discussed with support of experimental evidence. While some factors showed inconsistent effects, others show promise in controlling leaching mechanisms. These latter factors include initial water content, surface preparation, and time of pesticide application. Based on the reviewed literature recommendations were made for future research activities. 172 refs., 1 fig., 7 tabs.

  17. Experimental evidence for the formation of liquid saline water on Mars.

    PubMed

    Fischer, Erik; Martínez, Germán M; Elliott, Harvey M; Rennó, Nilton O

    2014-07-16

    Evidence for deliquescence of perchlorate salts has been discovered in the Martian polar region while possible brine flows have been observed in the equatorial region. This appears to contradict the idea that bulk deliquescence is too slow to occur during the short periods of the Martian diurnal cycle during which conditions are favorable for it. We conduct laboratory experiments to study the formation of liquid brines at Mars environmental conditions. We find that when water vapor is the only source of water, bulk deliquescence of perchlorates is not rapid enough to occur during the short periods of the day during which the temperature is above the salts' eutectic value, and the humidity is above the salts' deliquescence value. However, when the salts are in contact with water ice, liquid brine forms in minutes, indicating that aqueous solutions could form temporarily where salts and ice coexist on the Martian surface and in the shallow subsurface.

  18. The Impact of Smoking Bans on Smoking and Consumer Behavior: Quasi-Experimental Evidence from Switzerland.

    PubMed

    Boes, Stefan; Marti, Joachim; Maclean, Johanna Catherine

    2015-11-01

    In this paper, we exploit the progressive implementation of smoking bans in public venues at the state level in Switzerland to evaluate both the direct effects on smoking and the potential unintended consequences of these legislations on consumer behaviors as measured by visiting restaurants/bars and discos ('going out'). Our results indicate that public venue smoking bans in Switzerland reduce smoking rates, but the findings do not emerge until 1 year following the ban. This pattern of results is consistent with delays in ban enforcement on the part of business owners, difficulties in changing addictive behaviors such as smoking, and/or learning on the part of smokers. We find evidence that smoking bans influence going-out behavior and there is substantial heterogeneity across venue and consumer characteristics.

  19. Biparental incubation-scheduling: no experimental evidence for major energetic constraints

    PubMed Central

    Cresswell, Will; Rutten, Anne L.; Valcu, Mihai; Kempenaers, Bart

    2015-01-01

    Incubation is energetically demanding, but it is debated whether these demands constrain incubation-scheduling (i.e., the length, constancy, and timing of incubation bouts) in cases where both parents incubate. Using 2 methods, we experimentally reduced the energetic demands of incubation in the semipalmated sandpiper, a biparental shorebird breeding in the harsh conditions of the high Arctic. First, we decreased the demands of incubation for 1 parent only by exchanging 1 of the 4 eggs for an artificial egg that heated up when the focal bird incubated. Second, we reanalyzed the data from the only published experimental study that has explicitly tested energetic constraints on incubation-scheduling in a biparentally incubating species (Cresswell et al. 2003). In this experiment, the energetic demands of incubation were decreased for both parents by insulating the nest cup. We expected that the treated birds, in both experiments, would change the length of their incubation bouts, if biparental incubation-scheduling is energetically constrained. However, we found no evidence that heating or insulation of the nest affected the length of incubation bouts: the combined effect of both experiments was an increase in bout length of 3.6min (95% CI: −33 to 40), which is equivalent to a 0.5% increase in the length of the average incubation bout. These results demonstrate that the observed biparental incubation-scheduling in semipalmated sandpipers is not primarily driven by energetic constraints and therefore by the state of the incubating bird, implying that we still do not understand the factors driving biparental incubation-scheduling. PMID:25713473

  20. Biparental incubation-scheduling: no experimental evidence for major energetic constraints.

    PubMed

    Bulla, Martin; Cresswell, Will; Rutten, Anne L; Valcu, Mihai; Kempenaers, Bart

    2015-01-01

    Incubation is energetically demanding, but it is debated whether these demands constrain incubation-scheduling (i.e., the length, constancy, and timing of incubation bouts) in cases where both parents incubate. Using 2 methods, we experimentally reduced the energetic demands of incubation in the semipalmated sandpiper, a biparental shorebird breeding in the harsh conditions of the high Arctic. First, we decreased the demands of incubation for 1 parent only by exchanging 1 of the 4 eggs for an artificial egg that heated up when the focal bird incubated. Second, we reanalyzed the data from the only published experimental study that has explicitly tested energetic constraints on incubation-scheduling in a biparentally incubating species (Cresswell et al. 2003). In this experiment, the energetic demands of incubation were decreased for both parents by insulating the nest cup. We expected that the treated birds, in both experiments, would change the length of their incubation bouts, if biparental incubation-scheduling is energetically constrained. However, we found no evidence that heating or insulation of the nest affected the length of incubation bouts: the combined effect of both experiments was an increase in bout length of 3.6min (95% CI: -33 to 40), which is equivalent to a 0.5% increase in the length of the average incubation bout. These results demonstrate that the observed biparental incubation-scheduling in semipalmated sandpipers is not primarily driven by energetic constraints and therefore by the state of the incubating bird, implying that we still do not understand the factors driving biparental incubation-scheduling.

  1. Quasi-experimental evidence on the causal effects of physical health on mental health.

    PubMed

    Mohanan, Manoj; Maselko, Joanna

    2010-04-01

    While a large body of literature has demonstrated an association between physical health problems and psychiatric ones, the extent to which one is causally linked to the other remains difficult to estimate. This quasi-experimental study seeks to (i) estimate causal effects of an acute negative health event (health shock) on mental health and (ii) examine the role of debt and disability as potential mediators. The study design employs exogenous injuries in bus accidents together with a matching procedure to simulate a random exposure to physical health shock. The study was conducted among travellers on state-owned buses in Karnataka, India. Exposure occurred between July and December 2005. Outcomes were assessed from a household survey conducted in November-December 2006. Eighty-four injured passengers identified from bus accident compensation records were interviewed along with 336 unexposed individuals enrolled from passengers on the same accident bus routes, matched on age group, gender and village/neighbourhood of residence. The main outcome of Psychological Distress was measured using the Kessler-10 scale. Exposure to the health shock increases psychological distress by 1.5 standard deviations (SD) 1 year later (P < 0.01). Physical disability is a key mediating mechanism, accounting for 65% of the observed effect. After controlling for disability, odds of having distress levels commensurate with moderate/severe mental illness was 3.01 [95% confidence interval (CI) 1.26-7.19]. Indebtedness resulting from the health shock did not mediate the association between shock and distress. Evidence from this quasi-experimental study supports the hypothesis that acute physical health shocks can cause long-term mental health problems.

  2. Time-lag in extinction dynamics in experimental populations: evidence for a genetic Allee effect?

    PubMed Central

    Vercken, Elodie; Vincent, Flora; Mailleret, Ludovic; Ris, Nicolas; Tabone, Elisabeth; Fauvergue, Xavier; Gurney, William

    2013-01-01

    1. Propagule pressure, i.e. the number of individuals introduced, is thought to be a major predictor of the establishment success of introduced populations in the field. Its influence in laboratory experimental systems has however been questioned. In fact, other factors involved in long-term population persistence, like habitat size, were usually found to explain most of the dynamics of experimental populations. 2. To better understand the respective influence of short- and long-term factors and their potential interaction on extinction dynamics in experimental systems, we investigated the influence of propagule pressure, habitat size and genetic background on the early dynamics of laboratory-based populations of a hymenopteran parasitoid. 3. The amount of demographic variance differed between establishment and persistence phase and was influenced by habitat size and genetic background (geographic strain), but independent of propagule pressure. In contrast, the probability of extinction within five generations depended on the genetic background and on the interaction between propagule pressure and habitat size. Vulnerability to extinction in small size habitats was increased when populations were founded with a small number of individuals, but this effect was delayed until the third to fifth generations. 4. These results indicate that demographic stochasticity is influential during population establishment, but is not affected by the genetic variability of propagules. On the other hand, extinction might be influenced by a genetic Allee effect triggered by the combination of low propagule pressure and genetic drift. Finally, we documented consistent differences between genetic backgrounds in both deterministic and stochastic population dynamics patterns, with major consequences on extinction risk and ultimately population establishment. PMID:23398653

  3. High Pressure Experimental Studies on CuO: Indication of Re-entrant Multiferroicity at Room Temperature

    NASA Astrophysics Data System (ADS)

    Jana, Rajesh; Saha, Pinku; Pareek, Vivek; Basu, Abhisek; Kapri, Sutanu; Bhattacharyya, Sayan; Mukherjee, Goutam Dev

    2016-08-01

    We have carried out detailed experimental investigations on polycrystalline CuO using dielectric constant, dc resistance, Raman spectroscopy and X-ray diffraction measurements at high pressures. Observation of anomalous changes both in dielectric constant and dielectric loss in the pressure range 3.7–4.4 GPa and reversal of piezoelectric current with reversal of poling field direction indicate to a change in ferroelectric order in CuO at high pressures. A sudden jump in Raman integrated intensity of Ag mode at 3.4 GPa and observation of Curie-Weiss type behaviour in dielectric constant below 3.7 GPa lends credibility to above ferroelectric transition. A slope change in the linear behaviour of the Ag mode and a minimum in the FWHM of the same indicate indirectly to a change in magnetic ordering. Since all the previous studies show a strong spin-lattice interaction in CuO, observed change in ferroic behaviour at high pressures can be related to a reentrant multiferroic ordering in the range 3.4 to 4.4 GPa, much earlier than predicted by theoretical studies. We argue that enhancement of spin frustration due to anisotropic compression that leads to change in internal lattice strain brings the multiferroic ordering to room temperature at high pressures.

  4. High Pressure Experimental Studies on CuO: Indication of Re-entrant Multiferroicity at Room Temperature

    PubMed Central

    Jana, Rajesh; Saha, Pinku; Pareek, Vivek; Basu, Abhisek; Kapri, Sutanu; Bhattacharyya, Sayan; Mukherjee, Goutam Dev

    2016-01-01

    We have carried out detailed experimental investigations on polycrystalline CuO using dielectric constant, dc resistance, Raman spectroscopy and X-ray diffraction measurements at high pressures. Observation of anomalous changes both in dielectric constant and dielectric loss in the pressure range 3.7–4.4 GPa and reversal of piezoelectric current with reversal of poling field direction indicate to a change in ferroelectric order in CuO at high pressures. A sudden jump in Raman integrated intensity of Ag mode at 3.4 GPa and observation of Curie-Weiss type behaviour in dielectric constant below 3.7 GPa lends credibility to above ferroelectric transition. A slope change in the linear behaviour of the Ag mode and a minimum in the FWHM of the same indicate indirectly to a change in magnetic ordering. Since all the previous studies show a strong spin-lattice interaction in CuO, observed change in ferroic behaviour at high pressures can be related to a reentrant multiferroic ordering in the range 3.4 to 4.4 GPa, much earlier than predicted by theoretical studies. We argue that enhancement of spin frustration due to anisotropic compression that leads to change in internal lattice strain brings the multiferroic ordering to room temperature at high pressures. PMID:27530329

  5. EXPERIMENTAL EVIDENCE FOR WATER FORMATION VIA OZONE HYDROGENATION ON DUST GRAINS AT 10 K

    SciTech Connect

    Mokrane, H.; Chaabouni, H.; Accolla, M.; Congiu, E.; Dulieu, F.; Chehrouri, M.; Lemaire, J. L.

    2009-11-10

    The formation of water molecules from the reaction between ozone (O{sub 3}) and D-atoms is studied experimentally for the first time. Ozone is deposited on non-porous amorphous solid water ice (H{sub 2}O), and D-atoms are then sent onto the sample held at 10 K. HDO molecules are detected during the desorption of the whole substrate where isotope mixing takes place, indicating that water synthesis has occurred. The efficiency of water formation via hydrogenation of ozone is of the same order of magnitude as that found for reactions involving O-atoms or O{sub 2} molecules and exhibits no apparent activation barrier. These experiments validate the assumption made by models using ozone as one of the precursors of water formation via solid-state chemistry on interstellar dust grains.

  6. Natural and experimental evidence of melt lubrication of faults during earthquakes.

    PubMed

    Di Toro, Giulio; Hirose, Takehiro; Nielsen, Stefan; Pennacchioni, Giorgio; Shimamoto, Toshihiko

    2006-02-03

    Melt produced by friction during earthquakes may act either as a coseismic fault lubricant or as a viscous brake. Here we estimate the dynamic shear resistance (tau(f)) in the presence of friction-induced melts from both exhumed faults and high-velocity (1.28 meters per second) frictional experiments. Exhumed faults within granitoids (tonalites) indicate low tau(f) at 10 kilometers in depth. Friction experiments on tonalite samples show that tau(f) depends weakly on normal stress. Extrapolation of experimental data yields tau(f) values consistent with the field estimates and well below the Byerlee strength. We conclude that friction-induced melts can lubricate faults at intermediate crustal depths.

  7. Passive Facebook usage undermines affective well-being: Experimental and longitudinal evidence.

    PubMed

    Verduyn, Philippe; Lee, David Seungjae; Park, Jiyoung; Shablack, Holly; Orvell, Ariana; Bayer, Joseph; Ybarra, Oscar; Jonides, John; Kross, Ethan

    2015-04-01

    Prior research indicates that Facebook usage predicts declines in subjective well-being over time. How does this come about? We examined this issue in 2 studies using experimental and field methods. In Study 1, cueing people in the laboratory to use Facebook passively (rather than actively) led to declines in affective well-being over time. Study 2 replicated these findings in the field using experience-sampling techniques. It also demonstrated how passive Facebook usage leads to declines in affective well-being: by increasing envy. Critically, the relationship between passive Facebook usage and changes in affective well-being remained significant when controlling for active Facebook use, non-Facebook online social network usage, and direct social interactions, highlighting the specificity of this result. These findings demonstrate that passive Facebook usage undermines affective well-being.

  8. Three is a crowd in iterated prisoner's dilemmas: experimental evidence on reciprocal behavior

    PubMed Central

    Grujić, Jelena; Eke, Burcu; Cabrales, Antonio; Cuesta, José A.; Sánchez, Angel

    2012-01-01

    Reciprocity or conditional cooperation is one of the most prominent mechanisms proposed to explain the emergence of cooperation in social dilemmas. Recent experimental findings on networked games suggest that conditional cooperation may also depend on the previous action of the player. We here report on experiments on iterated, multi-player Prisoner's dilemma, on groups of 2 to 5 people. We confirm the dependence on the previous step and that memory effects for earlier periods are not significant. We show that the behavior of subjects in pairwise dilemmas is qualitatively different from the cases with more players; After an initial decay, cooperation increases significantly reaching values above 80%. The strategy of the players is rather universal as far as their willingness to reciprocate cooperation is concerned, whereas there is much diversity in their initial propensity to cooperate. Our results indicate that, for cooperation to emerge and thrive, three is a crowd. PMID:22962633

  9. The Trace-Component Trapping Effect: Experimental Evidence, Theoretical Interpretation, and Geochemical Applications

    NASA Astrophysics Data System (ADS)

    Urusov, Vadim S.; Dudnikova, Valentina B.

    1998-04-01

    Experimental data indicating increase of crystal-melt (fluid) partition coefficients in the range of microconcentrations of trace elements are reviewed and analyzed in detail. This concentration dependence of partition coefficients has been referred to as either deviations from Henry's law or the trace-component trapping effect. A critical review of a variety of models proposed to explain this phenomenon is also given. It is shown that the most reasonable and developed of these models relate changes in trace element partition coefficient at low concentrations to interactions between the trace element ions and metastable lattice defects (i.e., linear and planar defects) at low temperatures or intrinsic point defects of thermal origin at higher temperatures. The mechanism of interaction between trace element substituent atoms and intrinsic defects is considered in detail, with particular consideration given to the creation of pair associates, coupled substitutions, and the influence of other impurities on the trace element dissolution. The models developed are fit to the available experimental data to provide descriptions of the dependence of partition coefficients on composition and to estimate the concentrations and free energies of formation of the intrinsic defects (i.e., vacancies and interstitial atoms) in a matrix crystal. Some probable geochemical applications and manifestations of the trapping effect are discussed. This leads to the conclusion that there is an urgent need for further consideration of the problem.

  10. Reaction time effects in lab- versus Web-based research: Experimental evidence.

    PubMed

    Hilbig, Benjamin E

    2016-12-01

    Although Web-based research is now commonplace, it continues to spur skepticism from reviewers and editors, especially whenever reaction times are of primary interest. Such persistent preconceptions are based on arguments referring to increased variation, the limits of certain software and technologies, and a noteworthy lack of comparisons (between Web and lab) in fully randomized experiments. To provide a critical test, participants were randomly assigned to complete a lexical decision task either (a) in the lab using standard experimental software (E-Prime), (b) in the lab using a browser-based version (written in HTML and JavaScript), or (c) via the Web using the same browser-based version. The classical word frequency effect was typical in size and corresponded to a very large effect in all three conditions. There was no indication that the Web- or browser-based data collection was in any way inferior. In fact, if anything, a larger effect was obtained in the browser-based conditions than in the condition relying on standard experimental software. No differences between Web and lab (within the browser-based conditions) could be observed, thus disconfirming any substantial influence of increased technical or situational variation. In summary, the present experiment contradicts the still common preconception that reaction time effects of only a few hundred milliseconds cannot be detected in Web experiments.

  11. Bisphenol A and Reproductive Health: Update of Experimental and Human Evidence, 2007–2013

    PubMed Central

    Peretz, Jackye; Vrooman, Lisa; Ricke, William A.; Hunt, Patricia A.; Ehrlich, Shelley; Hauser, Russ; Padmanabhan, Vasantha; Taylor, Hugh S.; Swan, Shanna H.; VandeVoort, Catherine A.

    2014-01-01

    health: update of experimental and human evidence, 2007–2013. Environ Health Perspect 122:775–786; http://dx.doi.org/10.1289/ehp.1307728 PMID:24896072

  12. Sugars as source indicators of biogenic organic carbon in aerosols collected above the Howland Experimental Forest, Maine

    NASA Astrophysics Data System (ADS)

    Medeiros, Patricia M.; Conte, Maureen H.; Weber, John C.; Simoneit, Bernd R. T.

    Bulk aerosols (>1 μm) were collected continuously above the canopy at the Howland Experimental Forest, Maine, USA from May to October 2002. Each sample integrated over an approximately 2-week period. Mono- and disaccharide sugars were extracted using a microscale technique and were analyzed as their TMS derivatives by gas chromatography-mass spectrometry (GC-MS). Concentrations of total aerosol sugars ranged from 10 to 180 ng m -3. Glucose was the most abundant sugar (40-75% of the total sugars). The monosaccharides arabinose, fructose, galactose, mannose, arabitol and mannitol, and the disaccharides sucrose, maltose and mycose (aka trehalose) were also present in lower concentrations. The sugar composition in the aerosols varied seasonally. Fructose and sucrose were prevalent in early spring and decreased in relative abundance as the growing season progressed. Sugar polyols (arabitol and mannitol) and the disaccharide mycose (a fungal metabolite) were more prevalent in autumn during the period of leaf senescence. The changes in the sugar composition in the aerosol samples appear to reflect the seasonality of sugar production and utilization by the ecosystem. Plant waxes were present as significant components also indicating an input from biogenic background. Smoke plumes from Quebec forest fires passed over the Howland site in early July 2002. Levoglucosan, a biomarker of biomass burning, increased by an order of magnitude in the aerosol samples collected during this time. Glucose, mannose, arabinose, galactose, and also, plant waxes increased in concentration by factors of 2-5 in the smoke-impacted samples, indicating that wildfires enhance atmospheric emissions of uncombusted organic compounds. In contrast, concentrations of fructose, sugar polyols and disaccharides were not significantly higher in the smoke-impacted samples and indicated that biomass burning was not a significant source of these compounds in the aerosols.

  13. Experimental evidence of spatial memory and home range affinity in White-tailed Deer (Odocoileus virginianus)

    USGS Publications Warehouse

    Nelson, Michael E.

    2015-01-01

    The role of spatial memory in the movement of animals through landscapes remains elusive. To examine spatial memory and home range affinity of White-tailed Deer (Odocoileus virginianus) in northeastern Minnesota during 1995–2007, I translocated 17 adult does with known home ranges to unfamiliar sites and radio-tracked them after their release. Twelve does wearing transmitting radio-collars returned to their home ranges. Death and collar expiration precluded determination of whether the remaining five does would have returned to home ranges. Three of five does wearing global positioning system collars traveled throughout hundreds of square kilometres, circling, backtracking, and returning to release sites, while two others exhibited directional movement for tens of kilometres. Four does that survived to parturition stopped traveling and moved at hourly rates similar to those of control does during the first three weeks of the typical fawn-rearing period, but continued traveling later. Their aberrant extensive travel before and after interruption by parturition suggests that they recognized they were in unfamiliar areas, demonstrating both their capacity and propensity to search for and occupy the familiar space of their individual home ranges. Their successful return to home ranges provided experimental evidence of spatial memory and further elucidated its pervasive role in White-tailed Deer spatial ecology.

  14. Spontaneous Time Symmetry Breaking in System with Mixed Strategy Nash Equilibrium: Evidences in Experimental Economics Data

    NASA Astrophysics Data System (ADS)

    Wang, Zhijian; Xu, Bin; Zhejiang Collaboration

    2011-03-01

    In social science, laboratory experiment with human subjects' interaction is a standard test-bed for studying social processes in micro level. Usually, as in physics, the processes near equilibrium are suggested as stochastic processes with time-reversal symmetry (TRS). To the best of our knowledge, near equilibrium, the breaking time symmetry, as well as the existence of robust time anti-symmetry processes, has not been reported clearly in experimental economics till now. By employing Markov transition method to analysis the data from human subject 2x2 Games with wide parameters and mixed Nash equilibrium, we study the time symmetry of the social interaction process near Nash equilibrium. We find that, the time symmetry is broken, and there exists a robust time anti-symmetry processes. We also report the weight of the time anti-symmetry processes in the total processes of each the games. Evidences in laboratory marketing experiments, at the same time, are provided as one-dimension cases. In these cases, time anti-symmetry cycles can also be captured. The proposition of time anti-symmetry processes is small, but the cycles are distinguishable.

  15. Experimental Evidence for an Eco-Evolutionary Coupling between Local Adaptation and Intraspecific Competition.

    PubMed

    Siepielski, Adam M; Nemirov, Alex; Cattivera, Matthew; Nickerson, Avery

    2016-04-01

    Determining how adaptive evolution can be coupled to ecological processes is key for developing a more integrative understanding of the demographic factors that regulate populations. Intraspecific competition is an especially important ecological process because it generates negative density dependence in demographic rates. Although ecological factors are most often investigated to determine the strength of density dependence, evolutionary processes such as local adaptation could also feed back to shape variation in the strength of density dependence among populations. Using an experimental approach with damselflies, a predaceous aquatic insect, we find evidence that both density-dependent intraspecific competition and local adaptation can reduce per capita growth rates. In some cases, the effects of local adaptation on reducing per capita growth rates exceeded the ecological competitive effects of a doubling of density. However, we also found that these ecological and evolutionary properties of populations are coupled, and we offer two interpretations of the causes underlying this pattern: (1) the strength of density-dependent competition depends on the extent of local adaptation, or (2) the extent of local adaptation is shaped by the strength of density-dependent competition. Regardless of the underlying causal pathway, these results show how eco-evolutionary dynamics can affect a key demographic process regulating populations.

  16. Effect of insulin-induced hypoglycaemia on the central nervous system: evidence from experimental studies.

    PubMed

    Jensen, V F H; Bøgh, I B; Lykkesfeldt, J

    2014-03-01

    Insulin-induced hypoglycaemia (IIH) is a major acute complication in type 1 as well as in type 2 diabetes, particularly during intensive insulin therapy. The brain plays a central role in the counter-regulatory response by eliciting parasympathetic and sympathetic hormone responses to restore normoglycaemia. Brain glucose concentrations, being approximately 15-20% of the blood glucose concentration in humans, are rigorously maintained during hypoglycaemia through adaptions such as increased cerebral glucose transport, decreased cerebral glucose utilisation and, possibly, by using central nervous system glycogen as a glucose reserve. However, during sustained hypoglycaemia, the brain cannot maintain a sufficient glucose influx and, as the cerebral hypoglycaemia becomes severe, electroencephalogram changes, oxidative stress and regional neuronal death ensues. With particular focus on evidence from experimental studies on nondiabetic IIH, this review outlines the central mechanisms behind the counter-regulatory response to IIH, as well as cerebral adaption to avoid sequelae of cerebral neuroglycopaenia, including seizures and coma. © 2014 British Society for Neuroendocrinology.

  17. Experimental evidence for type-II Dirac semimetal in PtSe2

    NASA Astrophysics Data System (ADS)

    Zhang, Kenan; Yan, Mingzhe; Zhang, Haoxiong; Huang, Huaqing; Arita, Masashi; Sun, Zhe; Duan, Wenhui; Wu, Yang; Zhou, Shuyun

    2017-09-01

    While a monolayer PtSe2 film is a semiconductor with interesting spin structure, bulk PtSe2 crystal has been predicted to be a topological Dirac semimetal that can host a new type of Lorentz-violating Dirac fermions. Despite the intriguing predictions, experimental progress on the electronic structure of bulk PtSe2 has been hindered due to the lack of large, high-quality single-crystal samples. Here we report the growth and characterization of high-quality PtSe2 single crystals and reveal the electronic structure to provide direct evidence for the existence of three-dimensional type-II Dirac fermions. A comparison of the crystal, vibrational, and electronic structure to a related compound, PtTe2, is also discussed. Our work provides an important platform for exploring the novel quantum phenomena associated with type-II Dirac fermions in the 1 T -PtSe2 class of transition-metal dichalcogenides.

  18. The fishermen were right: experimental evidence for tributary refuge hypothesis during floods.

    PubMed

    Koizumi, Itsuro; Kanazawa, Yukiyo; Tanaka, Yuuki

    2013-05-01

    Fishermen often anecdotally report an unexpected increase of fish caught in small tributary streams during floods, presumably due to refuge-seeking behavior from the main stem. From a population perspective, this implies the significance of refuge habitats and connectivity for population viability against natural disturbances. Despite the plausibility, however, surprisingly few studies have examined the tributary refuge hypothesis, mainly due to the difficulty in field survey during floods. Here, we made use of a large-scale controlled flood to assess whether fishes move into tributaries during flooding in the main stem. A planned water release from the Satsunai River Dam located on Hokkaido Island in Japan rapidly increased the main stem discharge by more than 20-fold. Before, during, and after flooding censuses in four tributaries provided evidence of the refuge-seeking behavior of fishes from the main stem. For example, more than 10 Dolly Varden char, a salmonid fish, were caught in a tributary during the flood, even though almost no individuals were captured before or after the flood. The fish responded immediately to the flooding, suggesting the need for studies during disturbances. In addition, the likelihood of refuge movements varied among tributaries, suggesting the importance of local environmental differences between tributary and the main stem habitats. This is the first study to experimentally confirm the tributary refuge hypothesis, and underscores the roles of habitat diversity and connectivity during disturbances, even though some habitats are not used during normal conditions.

  19. Self-deception as self-signalling: a model and experimental evidence

    PubMed Central

    Mijović-Prelec, Danica; Prelec, Draz̆en

    2010-01-01

    Self-deception has long been the subject of speculation and controversy in psychology, evolutionary biology and philosophy. According to an influential ‘deflationary’ view, the concept is an over-interpretation of what is in reality an instance of motivationally biased judgement. The opposite view takes the interpersonal deception analogy seriously, and holds that some part of the self actively manipulates information so as to mislead the other part. Building on an earlier self-signalling model of Bodner and Prelec, we present a game-theoretic model of self-deception. We propose that two distinct mechanisms collaborate to produce overt expressions of belief: a mechanism responsible for action selection (including verbal statements) and an interpretive mechanism that draws inferences from actions and generates emotional responses consistent with the inferences. The model distinguishes between two modes of self-deception, depending on whether the self-deceived individual regards his own statements as fully credible. The paper concludes with a new experimental study showing that self-deceptive judgements can be reliably and repeatedly elicited with financial incentives in a categorization task, and that the degree of self-deception varies with incentives. The study also finds evidence of the two forms of self-deception. The psychological benefits of self-deception, as measured by confidence, peak at moderate levels. PMID:20026461

  20. Experimental and Computational Evidence of the Biradical Structure and Reactivity of Titanium(IV) Enolates.

    PubMed

    Heras, Carlos; Gómez-Palomino, Alejandro; Romea, Pedro; Urpí, Fèlix; Bofill, Josep Maria; Moreira, Ibério de P R

    2017-09-01

    Quantum chemical calculations have unveiled the unexpected biradical character of titanium(IV) enolates from N-acyl oxazolidinones and thiazolidinethiones. The electronic structure of these species therefore involves a valence tautomerism consisting of an equilibrium between a closed shell (formally Ti(IV) enolates) and an open shell, biradical, singlet (formally Ti(III) enolates) electronic states, whose origin is to be basically found in changes of the Ti-O distance. Spectroscopic studies of the intermediate species lend support to such a model, which also turns out to be crucial for a better understanding of the overall reactivity of titanium(IV) enolates. In this context, a thorough computational analysis of the radical addition of titanium(IV) enolates from N-acyl oxazolidinones to TEMPO has permitted us to suggest an entire mechanism, which accounts for the experimental details and the diastereoselectivity of the process. All together, this evidence highlights the relevance of biradical intermediates from titanium(IV) enolates and may be a useful contribution to the foundations of a more insightful comprehension of the structure and reactivity of titanium(IV) enolates.

  1. Experimental evidence that microbial activity lowers the albedo of glacier surfaces: the cryoconite casserole experiment.

    NASA Astrophysics Data System (ADS)

    Musilova, M.; Tranter, M.; Takeuchi, N.; Anesio, A. M.

    2014-12-01

    Darkened glacier and ice sheet surfaces have lower albedos, absorb more solar radiation and consequently melt more rapidly. The increase in glacier surface darkening is an important positive feedback to warming global temperatures, leading to ever growing world-wide ice mass loss. Most studies focus primarily on glacial albedo darkening caused by the physical properties of snow and ice surfaces, and the deposition of dark impurities on glaciers. To date, however, the important effects of biological activity have not been included in most albedo reduction models. This study provides the first experimental evidence that microbial activity can significantly decrease the albedo of glacier surfaces. An original laboratory experiment, the cryoconite casserole, was designed to test the microbial darkening of glacier surface debris (cryoconite) under simulated Greenlandic summer conditions. It was found that minor fertilisation of the cryoconite (at nutrient concentrations typical of glacial ice melt) stimulated extensive microbial activity. Microbes intensified their organic carbon fixation and even mined phosphorous out of the glacier surface sediment. Furthermore, the microbial organic carbon production, accumulation and transformation caused the glacial debris to darken further by 17.3% reflectivity (albedo analogue). These experiments are consistent with the hypothesis that enhanced fertilisation by anthropogenic inputs results in substantial amounts of organic carbon fixation, debris darkening and ultimately to a considerable decrease in the ice albedo of glacier surfaces on global scales. The sizeable amounts of microbially produced glacier surface organic matter and nutrients can thus be a vital source of bioavailable nutrients for subglacial and downstream environments.

  2. Fluorine as a hydrogen-bond acceptor: experimental evidence and computational calculations.

    PubMed

    Dalvit, Claudio; Invernizzi, Christian; Vulpetti, Anna

    2014-08-25

    Hydrogen-bonding interactions play an important role in many chemical and biological systems. Fluorine acting as a hydrogen-bond acceptor in intermolecular and intramolecular interactions has been the subject of many controversial discussions and there are different opinions about it. Recently, we have proposed a correlation between the propensity of fluorine to be involved in hydrogen bonds and its (19)F NMR chemical shift. We now provide additional experimental and computational evidence for this correlation. The strength of hydrogen-bond complexes involving the fluorine moieties CH2F, CHF2, and CF3 was measured and characterized in simple systems by using established and novel NMR methods and compared to the known hydrogen-bond complex formed between acetophenone and p-fluorophenol. Implications of these results for (19)F NMR screening are analyzed in detail. Computed values of the molecular electrostatic potential at the different fluorine atoms and the analysis of the electron density topology at bond critical points correlate well with the NMR results.

  3. A review of experimental methylmercury toxicity in rats: neuropathology and evidence for apoptosis.

    PubMed

    Nagashima, K

    1997-01-01

    As an animal model for examining the pathogenicity of human organic mercury intoxication, rats have been used for the reproduction of human neurologic diseases. Rats experimentally exposed to methylmercury chloride showed clinical signs of neurologic dysfunction characterized by ataxic behavior. Neuropathology of the diseased animals consisted of lesions such as: (a) degeneration of the peripheral nerve and sensory root nerve with preservation of the motor root nerve; (b) degeneration of the posterior funiculus of the spinal cord; and (c) degeneration of cerebellar granule cells with preservation of Purkinje cells. These findings suggest the human neuropathology of this toxicity. The degeneration was characterized by nerve fiber damage or neuronal cell death accompanied by astrocytic gliosis and activated macrophages or microglias. For the cerebellar granule cells, the mechanism of neuronal cell death was shown to be apoptosis. This fact was verified by histologic and ultrastructural findings as well as by in situ nick-end labeling and electrophoretic methods. Evidence of apoptosis involvement in cerebellar degeneration would provide a new viewpoint from which to analyze the selected degeneration of the nervous system in neurotoxicology.

  4. Electrical Stimulation of Wound Healing: A Review of Animal Experimental Evidence

    PubMed Central

    Torkaman, Giti

    2014-01-01

    Significance: Electrical stimulation (ES) is a therapeutic intervention that may help specialists facilitate wound healing rates. The purpose of this section is to compile the available animal research regarding the effectiveness of ES on the injury potential, healing rate, cellular and molecular proliferation, mechanical properties, and survival rate of skin flaps. Recent Advances: Regardless of the type of ES current and polarity used, most of the animal experimental evidence suggests that application of ES can facilitate wound healing. However, treatment time should be sufficiently long to attain good mechanical strength of regenerated tissue, because tensile strength is not consistent with augmented collagen deposition. ES improves the survival rate and skin blood flow of animal flaps, but clinical studies are needed to substantiate the findings from these animal experiments. Critical Issues: Impaired or delayed healing is a major clinical problem that can lead to wound chronicity. ES with various strategies has been used to facilitate the healing process, but many aspects remain controversial. Despite much research, no consensus exists regarding the detailed effects of ES on wound healing. Nevertheless, ES has been approved by the Center for Medicare and Medicine Services for reimbursement of the treatment of some chronic ulcers. Future Directions: Exogenous ES may promote the directional migration of cells and signaling molecules via electrotaxis; however, its underlying mechanism is still poorly understood. Future studies that further elucidate the mechanisms regulating electrotaxis will be necessary to optimize the use of ES in different wound states. PMID:24761359

  5. Experimental Evidence of Edge Fluctuation Broadening of ECH Deposition at DIII-D

    NASA Astrophysics Data System (ADS)

    Brookman, M. W.; Austin, M. E.; Gentle, K. W.; Petty, C. C.; Peysson, Y.; Decker, J.; Barada, K.; Ernst, D. E.

    2016-10-01

    This work provides experimental evidence for broadening of the ECH and ECCD deposition by edge density fluctuations. Results on the DIII-D tokamak suggest a deposition FWHM 1.7-2.8 times wider than TORAY-GA. A 1D ECH deposition profile was measured through gyrotron power modulation. From 500 kHz, 48-channel ECE measurements and trial ECH deposition functions, a Fourier transformed heat flux is found and fit to transport drive terms. Radially broader ECH deposition best fit calculated fluxes in discharges with higher levels of edge density turbulence. Broadening of deposition does not arise from anomalous transport, which is minimal on DIII-D. Simulation and theory suggest edge (ρ.9) turbulent n _ e fluctuations refract RF waves that pass through them, broadening radial deposition of ECH and ECCD. On ITER, this effect could hinder NTM suppression by broadening ECCD deposition outside the 3/2 island. Work supported by the U.S. DOE under Award DE-FC02-04ER54698.

  6. Withanone binds to mortalin and abrogates mortalin-p53 complex: computational and experimental evidence.

    PubMed

    Grover, Abhinav; Priyandoko, Didik; Gao, Ran; Shandilya, Ashutosh; Widodo, Nashi; Bisaria, Virendra S; Kaul, Sunil C; Wadhwa, Renu; Sundar, Durai

    2012-03-01

    Mortalin binds to p53 tumor suppressor protein and sequesters it in the cytoplasm. This results in an inhibition of the transcriptional activation and control of centrosome duplication functions of p53, thus contributing to human carcinogenesis. Abrogation of mortalin-p53 interaction and reactivation of p53 function could be a valid proposition for cancer therapy. In the present study, we first investigated in silico the interaction of withanone, a withanolide with anticancer activity, with mortalin. We found that withanone could bind to mortalin in a region, earlier predicted critical for binding to p53. Cationic rhodacyanine dye, MKT-077 has also shown to bind the same region and kill cancer cells selectively. We report the molecular dynamic simulations revealing the thermodynamic and structural stability of the withanone-mortalin complexes. We also demonstrate the experimental evidence of abrogation of mortalin-p53 complex by withanone resulting in nuclear translocation and functional reactivation of p53 in human cancer cells. The present study establishes a molecular interaction basis that could be used for screening and development of anticancer drugs with low toxicity to normal cells. Accurate knowledge of the 3D structure of mortalin would further enhance the potential of such analyses to understand the molecular basis of mortalin biology and mortalin based cancer therapy.

  7. Experimental evidence that ecological effects of an invasive fish are reduced at high densities.

    PubMed

    Kornis, Matthew S; Carlson, Jedchada; Lehrer-Brey, Gabrielle; Vander Zanden, M Jake

    2014-05-01

    Understanding the relationship between invasive species density and ecological impact is a pressing topic in ecology, with implications for environmental management and policy. Although it is widely assumed that invasive species impact will increase with density, theory suggests interspecific competition may diminish at high densities due to increased intraspecific interactions. To test this theory, we experimentally examined intra- and interspecific interactions between a globally invasive fish, round goby (Neogobius melanostomus), and three native species at different round goby densities in a tributary of the Laurentian Great Lakes. Eighteen 2.25 m(2) enclosures were stocked with native fish species at natural abundances, while round gobies were stocked at three different densities: 0 m(-2), 2.7 m(-2), and 10.7 m(-2). After 52 days, native fish growth rate was significantly reduced in the low density goby treatment, while growth in the high density goby treatment mirrored the goby-free treatment for two of three native species. Invertebrate density and gut content weight of native fishes did not differ among treatments. Conversely, gut content weight and growth of round gobies were lower in the high goby density treatment, suggesting interactions between round gobies and native fishes are mediated by interference competition amongst gobies. Our experiment provides evidence that invasive species effects may diminish at high densities, possibly due to increased intraspecific interactions. This is consistent with some ecological theory, and cautions against the assumption that invasive species at moderate densities have low impact.

  8. Which is the best indicator of muscle oxygen extraction during exercise using NIRS?: Evidence that HHb is not the candidate.

    PubMed

    Kime, Ryotaro; Fujioka, Masako; Osawa, Takuya; Takagi, Shun; Niwayama, Masatsugu; Kaneko, Yasuhisa; Osada, Takuya; Murase, Norio; Katsumura, Toshihito

    2013-01-01

    Recently, deoxygenated hemoglobin (HHb) has been used as one of the most popular indicators of muscle O2 extraction during exercise in the field of exercise physiology. However, HHb may not sufficiently represent muscle O2 extraction, as total hemoglobin (tHb) is not stable during exercise. The purpose of this study was to measure various muscle oxygenation signals during cycle exercise and clarify which is the best indicator of muscle O2 extraction during exercise using NIRS. Ten healthy men performed 6-min cycle exercise at both moderate and heavy work rates. Oxygenated hemoglobin (O2-Hb), HHb, tHb, and muscle tissue oxygen saturation (SmO2) were measured with near-infrared spatial resolved spectroscopy from the vastus lateralis muscle. Skin blood flow (sBF) was also monitored at a site close to the NIRS probe. During moderate exercise, tHb, O2-Hb, and SmO2 displayed progressive increases until the end of exercise. In contrast, HHb remained stable during moderate work rate. sBF remained stable during moderate exercise but showed a progressive decrease at heavy work rate. These results provide evidence that HHb may not sufficiently represent muscle O2 extraction since tHb is not stable during exercise and HHb is insensitive to exercise-induced hyperaemia.

  9. Smectite clays in Mars soil: evidence for their presence and role in Viking biology experimental results.

    PubMed

    Banin, A; Rishpon, J

    1979-12-01

    Various chemical, physical and geological observations indicate that smectite clays are probably the major components of the Martian soil. Satisfactory ground-based chemical simulation of the Viking biology experimental results was obtained with the smectite clays nontronite and montmorillonite when they contained iron and hydrogen as adsorbed ions. Radioactive gas was released from the medium solution used in the Viking Labeled Release (LR) experiment when interacted with the clays, at rates and quantities similar to those measured by Viking on Mars. Heating of the active clay (mixed with soluble salts) to 160 degrees C in CO2 atmosphere reduced the decomposition activity considerably, again, as was observed on Mars. The decomposition reaction in LR experiment is postulated to be iron-catalyzed formate decomposition on the clay surface. The main features of the Viking Pyrolytic Release (PR) experiment were also simulated recently (Hubbard, 1979) which the iron clays, including a relatively low '1st peak' and significant '2nd peak'. The accumulated observations on various Martian soil properties and the results of simulation experiments, thus indicate that smectite clays are major and active components of the Martian soil. It now appears that many of the results of the Viking biology experiments can be explained on the basis of their surface activity in catalysis and adsorption.

  10. Testing the environmental Kuznets curve hypothesis with bird populations as habitat-specific environmental indicators: evidence from Canada.

    PubMed

    Lantz, Van; Martínez-Espiñeira, Roberto

    2008-04-01

    The traditional environmental Kuznets curve (EKC) hypothesis postulates that environmental degradation follows an inverted U-shaped relationship with gross domestic product (GDP) per capita. We tested the EKC hypothesis with bird populations in 5 different habitats as environmental quality indicators. Because birds are considered environmental goods, for them the EKC hypothesis would instead be associated with a U-shaped relationship between bird populations and GDP per capita. In keeping with the literature, we included other variables in the analysis-namely, human population density and time index variables (the latter variable captured the impact of persistent and exogenous climate and/or policy changes on bird populations over time). Using data from 9 Canadian provinces gathered over 37 years, we used a generalized least-squares regression for each bird habitat type, which accounted for the panel structure of the data, the cross-sectional dependence across provinces in the residuals, heteroskedasticity, and fixed- or random-effect specifications of the models. We found evidence that supports the EKC hypothesis for 3 of the 5 bird population habitat types. In addition, the relationship between human population density and the different bird populations varied, which emphasizes the complex nature of the impact that human populations have on the environment. The relationship between the time-index variable and the different bird populations also varied, which indicates there are other persistent and significant influences on bird populations over time. Overall our EKC results were consistent with those found for threatened bird species, indicating that economic prosperity does indeed act to benefit some bird populations.

  11. Experimental evidence for a new single-event upset (SEU) mode in a CMOS SRAM obtained from model verification

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.; Smith, L. S.; Soli, G. A.; Lo, R. Y.

    1987-01-01

    Modeling of SEU has been done in a CMOS static RAM containing 1-micron-channel-length transistors fabricated from a p-well epilayer process using both circuit-simulation and numerical-simulation techniques. The modeling results have been experimentally verified with the aid of heavy-ion beams obtained from a three-stage tandem van de Graaff accelerator. Experimental evidence for a novel SEU mode in an ON n-channel device is presented.

  12. Experimental evidence and isotopomer analysis of mixotrophic glucose metabolism in the marine diatom Phaeodactylum tricornutum.

    PubMed

    Zheng, Yuting; Quinn, Andrew H; Sriram, Ganesh

    2013-11-14

    Heterotrophic fermentation using simple sugars such as glucose is an established and cost-effective method for synthesizing bioproducts from bacteria, yeast and algae. Organisms incapable of metabolizing glucose have limited applications as cell factories, often despite many other advantageous characteristics. Therefore, there is a clear need to investigate glucose metabolism in potential cell factories. One such organism, with a unique metabolic network and a propensity to synthesize highly reduced compounds as a large fraction of its biomass, is the marine diatom Phaeodactylum tricornutum (Pt). Although Pt has been engineered to metabolize glucose, conflicting lines of evidence leave it unresolved whether Pt can natively consume glucose. Isotope labeling experiments in which Pt was mixotrophically grown under light on 100% U-(13)C glucose and naturally abundant (~99% (12)C) dissolved inorganic carbon resulted in proteinogenic amino acids with an average 13C-enrichment of 88%, thus providing convincing evidence of glucose uptake and metabolism. The dissolved inorganic carbon was largely incorporated through anaplerotic rather than photosynthetic fixation. Furthermore, an isotope labeling experiment utilizing 1-(13)C glucose and subsequent metabolic pathway analysis indicated that (i) the alternative Entner-Doudoroff and Phosphoketolase glycolytic pathways are active during glucose metabolism, and (ii) during mixotrophic growth, serine and glycine are largely synthesized from glyoxylate through photorespiratory reactions rather than from 3-phosphoglycerate. We validated the latter result for mixotrophic growth on glycerol by performing a 2-(13)C glycerol isotope labeling experiment. Additionally, gene expression assays showed that known, native glucose transporters in Pt are largely insensitive to glucose or light, whereas the gene encoding cytosolic fructose bisphosphate aldolase 3, an important glycolytic enzyme, is overexpressed in light but insensitive to

  13. Experimental evidence and isotopomer analysis of mixotrophic glucose metabolism in the marine diatom Phaeodactylum tricornutum

    PubMed Central

    2013-01-01

    Background Heterotrophic fermentation using simple sugars such as glucose is an established and cost-effective method for synthesizing bioproducts from bacteria, yeast and algae. Organisms incapable of metabolizing glucose have limited applications as cell factories, often despite many other advantageous characteristics. Therefore, there is a clear need to investigate glucose metabolism in potential cell factories. One such organism, with a unique metabolic network and a propensity to synthesize highly reduced compounds as a large fraction of its biomass, is the marine diatom Phaeodactylum tricornutum (Pt). Although Pt has been engineered to metabolize glucose, conflicting lines of evidence leave it unresolved whether Pt can natively consume glucose. Results Isotope labeling experiments in which Pt was mixotrophically grown under light on 100% U-13C glucose and naturally abundant (~99% 12C) dissolved inorganic carbon resulted in proteinogenic amino acids with an average 13C-enrichment of 88%, thus providing convincing evidence of glucose uptake and metabolism. The dissolved inorganic carbon was largely incorporated through anaplerotic rather than photosynthetic fixation. Furthermore, an isotope labeling experiment utilizing 1-13C glucose and subsequent metabolic pathway analysis indicated that (i) the alternative Entner-Doudoroff and Phosphoketolase glycolytic pathways are active during glucose metabolism, and (ii) during mixotrophic growth, serine and glycine are largely synthesized from glyoxylate through photorespiratory reactions rather than from 3-phosphoglycerate. We validated the latter result for mixotrophic growth on glycerol by performing a 2-13C glycerol isotope labeling experiment. Additionally, gene expression assays showed that known, native glucose transporters in Pt are largely insensitive to glucose or light, whereas the gene encoding cytosolic fructose bisphosphate aldolase 3, an important glycolytic enzyme, is overexpressed in light but

  14. Hydrogen movement into and out of fluid inclusions in quartz: Experimental evidence and geologic implications

    NASA Astrophysics Data System (ADS)

    Mavrogenes, J. A.; Bodnar, R. J.

    1994-01-01

    Natural chalcopyrite-bearing fluid inclusions from the Red Mountain, Arizona, porphyry copper prospect have been used to experimentally document the movement of hydrogen into and out of fluid inclusions in quartz. Chalcopyrite daughter minerals in inclusions do not dissolve during heating studies of "as collected" quartz vein material. However, after the samples were held at an elevated (but unknown) hydrogen pressure in a cold-seal-type pressure vessel at 600°C and 2.5 kbar for seven days, chalcopyrite daughter crystals in fluid inclusions dissolve easily and completely during subsequent heating. The presence of hydrogen in the re-equilibrated inclusions was confirmed by both Raman microprobe and quadrupole mass spectrometric analyses of the inclusions. Repeated heating of re-equilibrated inclusions to measure the dissolution temperature of chalcopyrite (Tm Cpy) results in a considerably higher Tm Cpy during each successive run until, eventually, the chalcopyrite no longer dissolves when heated to the upper limit of the heating stage. This behavior is interpreted to indicate that hydrogen which had diffused into inclusions during re-equilibration experiments diffused out of the inclusions during microthermometric analyses. The dissolution of chalcopyrite following re-equilibration and its failure to dissolve before re-equilibration are consistent with proposed solubility models for chalcopyrite in aqueous solutions. The rapid movement of hydrogen into inclusions is also consistent with experimentally determined diffusion rates for hydrogen through quartz. These results reinforce conclusions reached by earlier workers who suggested that the failure of some fluid inclusion daughter minerals to dissolve during heating is a result of hydrogen loss. These results also support earlier workers who have suggested that unexpectedly low δD values obtained from inclusion fluids were produced by the preferential movement of hydrogen (relative to deuterium) into fluid

  15. The temporal profile of cerebral blood flow and tissue metabolites indicates sustained metabolic depression after experimental subarachnoid hemorrhage in rats.

    PubMed

    Westermaier, Thomas; Jauss, Alina; Eriskat, Jörg; Kunze, Ekkehard; Roosen, Klaus

    2011-01-01

    Derangement of cerebral metabolism occurs after various insults such as ischemia, traumatic brain injury, and subarachnoid hemorrhage (SAH). To investigate the course of cerebral blood flow and metabolic parameters in the first hours after experimental SAH. Sixteen Sprague-Dawley rats were subjected to SAH using the endovascular filament model or served as controls (8 rats in each group). Local cerebral blood flow and intracranial pressure were measured continuously. Microdialysis samples were acquired in 30-minute intervals for 6 hours after SAH. Concentrations of glucose, lactate, pyruvate, and glutamate were determined. After induction of SAH, cerebral perfusion pressure and local cerebral blood flow sharply decreased. The decrease in local cerebral blood flow exceeded the decrease in cerebral perfusion pressure throughout the observation period. Glutamate concentrations in microdialysis samples increased sixfold and recovered to baseline levels. Lactate concentrations immediately increased after SAH, recovered incompletely, and remained above the levels of control animals until the end of the sampling period. Pyruvate concentrations showed a delayed increase starting 2 hours after SAH. The course of cerebral blood flow after SAH resembles global ischemia followed by a continuous low-flow state caused by a sudden decrease in cerebral perfusion pressure and acute vasoconstriction. The courses of lactate and pyruvate concentrations indicate a persistently deranged aerobic metabolism.

  16. Life in varying environments: experimental evidence for delayed effects of juvenile environment on adult life history.

    PubMed

    Helle, Heikki; Koskela, Esa; Mappes, Tapio

    2012-05-01

    1. The effects of environment experienced during early development on phenotype as an adult has started to gain vast amounts of interest in various taxa. Some evidence on long-term effects of juvenile environment is available, but replicated experimental studies in wild animals are still lacking. 2. Here we report the first replicated experiment in wild mammals which examines the long-term effects of juvenile and adult environments on individual fitness (reproduction, survival and health). The early development of bank vole (Myodes glareolus) individuals took place in either food-supplemented or un-supplemented outdoor enclosures. After the summer, adult individuals were reciprocally changed to either a similar or opposite resource environment to overwinter. 3. Adult environment had an overriding effect on reproductive success of females so that females overwintering in food-supplemented enclosures had a higher probability of breeding and advanced the initiation of breeding. However, the characteristics of their litters were determined by juvenile environment: females initially grown in food-supplemented conditions subsequently produced larger litters with bigger pups and a male-biased sex ratio. 4. In males, individuals growing in un-supplemented conditions had the highest survival irrespective of adult environment during winter, whereas in females, neither the juvenile nor adult environments affected their survival significantly. The physiological condition of voles in spring, as determined by haematological parameters, was also differentially affected by juvenile (plasma proteins and male testosterone) and adult (haematocrit) environments. 5. Our results suggest that (i) life-history trajectories of voles are not strictly specialized to a certain environment and (ii) the plastic life-history responses to present conditions can actually be caused by delayed effects of the juvenile environment. More generally, the results are important for understanding

  17. Nitrate ammonification by Nautilia profundicola AmH: experimental evidence consistent with a free hydroxylamine intermediate

    PubMed Central

    Hanson, Thomas E.; Campbell, Barbara J.; Kalis, Katie M.; Campbell, Mark A.; Klotz, Martin G.

    2013-01-01

    The process of nitrate reduction via nitrite controls the fate and bioavailability of mineral nitrogen within ecosystems; i.e., whether it is retained as ammonium (ammonification) or lost as nitrous oxide or dinitrogen (denitrification). Here, we present experimental evidence for a novel pathway of microbial nitrate reduction, the reverse hydroxylamine:ubiquinone reductase module (reverse-HURM) pathway. Instead of a classical ammonia-forming nitrite reductase that performs a 6 electron-transfer process, the pathway is thought to employ two catalytic redox modules operating in sequence: the reverse-HURM reducing nitrite to hydroxylamine followed by a hydroxylamine reductase that converts hydroxylamine to ammonium. Experiments were performed on Nautilia profundicola strain AmH, whose genome sequence led to the reverse-HURM pathway proposal. N. profundicola produced ammonium from nitrate, which was assimilated into biomass. Furthermore, genes encoding the catalysts of the reverse-HURM pathway were preferentially expressed during growth of N. profundicola on nitrate as an electron acceptor relative to cultures grown on polysulfide as an electron acceptor. Finally, nitrate-grown cells of N. profundicola were able to rapidly and stoichiometrically convert high concentrations of hydroxylamine to ammonium in resting cell assays. These experiments are consistent with the reverse-HURM pathway and a free hydroxylamine intermediate, but could not definitively exclude direct nitrite reduction to ammonium by the reverse-HURM with hydroxylamine as an off-pathway product. N. profundicola and related organisms are models for a new pathway of nitrate ammonification that may have global impact due to the wide distribution of these organisms in hypoxic environments and symbiotic or pathogenic associations with animal hosts. PMID:23847604

  18. Experimental Evidence for Cerenkov Emission of Whistler Waves by Electron Holes Associated with Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Eastwood, J. P.; Goldman, M. V.; Zhang, X.; Hietala, H.; Krupar, V.; Newman, D. L.; Angelopoulos, V.; Lapenta, G.

    2015-12-01

    Whistler waves are a ubiquitous plasma phenomenon, observed in a variety of space and laboratory plasma environments. They play a key role in many important and diverse processes, such as particle acceleration in the radiation belts and auroral acceleration region, the dissipation of plasma turbulence at small scales below the inertial range, collisionless shock physics, and magnetic reconnection. In reconnection they may modify the reconnection rate and also whistler physics is crucial to enabling fast reconnection in the Hall reconnection model. Consequently, understanding how whistler waves are generated and how they subsequently interact with the plasma is a problem of wide importance and application. It is well known that whistlers can arise as a result of kinetic instabilities, which grow exponentially from noise as a consequence of unstable electron distributions, for example temperature anisotropy. This is used ubiquitously to predict where and when whistler waves are likely to exist and therefore be of importance in many plasma phenomena. Recently it has been demonstrated theoretically and via computer simulations that whistler waves may also arise via Cerenkov emission from electron hole quasi-particles [Goldman et al., PRL, 2014]. Such wave emission can arise even when the temperature anisotropy leads to damping; in this case the system is analogous to a damped forced oscillator. Here we present novel experimental analysis from THEMIS showing for the first time evidence consistent with the generation of whistlers via Cerenkov emission during magnetotail reconnection. By considering the electromagnetic properties of the electron holes, the amplitude, phase speed and frequency of the associated whistlers, and also the available sub-spin observations of the electron distribution function, we find that the data are best explained by the Cerenkov emission theory rather than by kinetic instabilities due to the electron temperature anisotropy. Whilst the

  19. An hypothesis regarding the origin of aneuploidy in man: indirect evidence from an experimental model.

    PubMed Central

    Kaufman, M H

    1985-01-01

    Recent studies have clearly demonstrated that aneuploidy may be induced in about 10 to 20% of oocytes and recently ovulated eggs when female mice are given an intragastric injection of a dilute solution of ethanol. Similar rates of aneuploidy have also been observed when recently ovulated eggs are briefly exposed in vitro to a dilute solution of ethanol in tissue culture medium. These findings are briefly reviewed, and observations made on the possible underlying mechanism of induction of chromosome malsegregation in the ethanol exposed groups. Attention is drawn to evidence from a wide range of studies on the effect of ethanol, acetaldehyde (its primary metabolite), and anaesthetics on cell division and chromosome segregation in an attempt to substantiate an hypothesis regarding the mode of action of these agents. In the light of this information, it is hypothesised that exposure to ethanol probably interferes with the normal functioning of the cytoskeletal elements of the spindle apparatus, or its precursor elements, during the first or second meiotic divisions. An attempt is also made to account for the very high incidence of aneuploid conceptuses in man, a high proportion of which are spontaneously aborted. It is hypothesised that exposure to ethanol and other spindle active agents during appropriate stages of oogenesis (in particular during the first meiotic division), and possibly also during spermatogenesis, may be important aetiological factors in a proportion of those cases of spontaneous abortion with a numerical chromosome anomaly for which no other obvious cause is recognised. If it is valid to extrapolate from these experimental findings to the clinical situation in man, it is suggested that attention should also be drawn to the potentially greater hazard to the conceptus which could result from maternal alcohol consumption at and shortly before conception. PMID:4009642

  20. Designing a light fabric metamaterial being highly macroscopically tough under directional extension: first experimental evidence

    NASA Astrophysics Data System (ADS)

    dell'Isola, Francesco; Lekszycki, Tomasz; Pawlikowski, Marek; Grygoruk, Roman; Greco, Leopoldo

    2015-12-01

    In this paper, we study a metamaterial constructed with an isotropic material organized following a geometric structure which we call pantographic lattice. This relatively complex fabric was studied using a continuous model (which we call pantographic sheet) by Rivlin and Pipkin and includes two families of flexible fibers connected by internal pivots which are, in the reference configuration, orthogonal. A rectangular specimen having one side three times longer than the other is cut at 45° with respect to the fibers in reference configuration, and it is subjected to large-deformation plane-extension bias tests imposing a relative displacement of shorter sides. The continuum model used, the presented numerical models and the extraordinary advancements of the technology of 3D printing allowed for the design of some first experiments, whose preliminary results are shown and seem to be rather promising. Experimental evidence shows three distinct deformation regimes. In the first regime, the equilibrium total deformation energy depends quadratically on the relative displacement of terminal specimen sides: Applied resultant force depends linearly on relative displacement. In the second regime, the applied force varies nonlinearly on relative displacement, but the behavior remains elastic. In the third regime, damage phenomena start to occur until total failure, but the exerted resultant force continues to be increasing and reaches a value up to several times larger than the maximum shown in the linear regime before failure actually occurs. Moreover, the total energy needed to reach structural failure is larger than the maximum stored elastic energy. Finally, the volume occupied by the material in the fabric is a small fraction of the total volume, so that the ratio weight/resistance to extension is very advantageous. The results seem to require a refinement of the used theoretical and numerical methods to transform the presented concept into a promising technological

  1. The response of cerebral cortex to haemorrhagic damage: experimental evidence from a penetrating injury model.

    PubMed

    Purushothuman, Sivaraman; Marotte, Lauren; Stowe, Sally; Johnstone, Daniel M; Stone, Jonathan

    2013-01-01

    Understanding the response of the brain to haemorrhagic damage is important in haemorrhagic stroke and increasingly in the understanding the cerebral degeneration and dementia that follow head trauma and head-impact sports. In addition, there is growing evidence that haemorrhage from small cerebral vessels is important in the pathogenesis of age-related dementia (Alzheimer's disease). In a penetration injury model of rat cerebral cortex, we have examined the neuropathology induced by a needlestick injury, with emphasis on features prominent in the ageing and dementing human brain, particularly plaque-like depositions and the expression of related proteins. Needlestick lesions were made in neo- and hippocampal cortex in Sprague Dawley rats aged 3-5 months. Brains were examined after 1-30 d survival, for haemorrhage, for the expression of hyperphosphorylated tau, Aβ, amyloid precursor protein (APP), for gliosis and for neuronal death. Temporal cortex from humans diagnosed with Alzheimer's disease was examined with the same techniques. Needlestick injury induced long-lasting changes-haem deposition, cell death, plaque-like deposits and glial invasion-along the needle track. Around the track, the lesion induced more transient changes, particularly upregulation of Aβ, APP and hyperphosporylated tau in neurons and astrocytes. Reactions were similar in hippocampus and neocortex, except that neuronal death was more widespread in the hippocampus. In summary, experimental haemorrhagic injury to rat cerebral cortex induced both permanent and transient changes. The more permanent changes reproduced features of human senile plaques, including the formation of extracellular deposits in which haem and Aβ-related proteins co-localised, neuronal loss and gliosis. The transient changes, observed in tissue around the direct lesion, included the upregulation of Aβ, APP and hyperphosphorylated tau, not associated with cell death. The findings support the possibility that

  2. Experimental evidence for three pheromone races of the scarab beetle Phyllophaga anxia (LeConte).

    PubMed

    Robbins, Paul S; Cash, Daniel B; Linn, Charles E; Roelofs, Wendell L

    2008-02-01

    This study offers experimental evidence for the existence of three pheromone races of the northern genitalic form of Phyllophaga anxia: one race in which females produce and males respond mainly to L-valine methyl ester, a second producing and responding to L-isoleucine methyl ester, and a third producing and responding to an intermediate range of blends of the two compounds. At Franklinville, NY, pheromone gland contents of females were analyzed using coupled gas chromatography-electroantennogram detection. Two types of females were found, one that produced greater than 99% L-valine methyl ester and another that produced greater than 99% L-isoleucine methyl ester. Capture-mark-release-recapture field tests with males at Franklinville established that most males were recaptured in traps baited with the same blends with which they were originally captured. The populations characterized at Franklinville, NY, have also been found at numerous locations from eastern Canada and the northeast and north central USA, sometimes in allopatry and sometimes in sympatry. At a site in Carver, MA, P. anxia males responded to blends of the methyl esters of L-valine and L-isoleucine, and Carver females produced blends similar to those to which the males responded. Populations responding to blends have been identified only from southeastern Massachusetts and Rhode Island. At a field site near Waterloo, NY, the addition of small proportions of L-isoleucine methyl ester to lures containing L-valine methyl ester did not affect trap captures, but higher proportions of L-isoleucine methyl ester were inhibitory, decreasing trap captures.

  3. Racemic R,S-venlafaxine hydrochloride-DNA interaction: experimental and computational evidence.

    PubMed

    Shahabadi, Nahid; Hadidi, Saba; Ghasemian, Zeinab; Taherpour, Avat Arman

    2015-06-15

    The interaction of racemic R,S-venlafaxine hydrochloride (rac-VEN) drug with calf thymus deoxyribonucleic acid (ct-DNA) was studied using various physico-chemical techniques and molecular docking at simulated physiological conditions (pH=7.4). The fluorescence study shows that ct-DNA interacted with rac-VEN and quenched its intrinsic fluorescence in a static quenching process. These results are further supported by UV-Vis spectra. The binding constant of rac-VEN with ct-DNA (0.57 × 10(4)) obtained from the spectroscopic techniques, which is more in keeping with the groove binding with DNA. Furthermore, the competition experiment using Hoechst33258 indicated that rac-VEN may bind to ct-DNA by a minor groove binding mode. In addition, iodide quenching effect on the fluorescence of rac-VEN before and after the interaction with ct-DNA is another evidence to groove binding. The thermodynamic parameters are calculated by van't Hoff equation, which demonstrated that hydrogen bonds and van der Waals interactions played major roles in the binding reaction. Molecular simulation studies carried out by using the AutoDock4 and Spartan 10 programs. From the best docking map, we found that R and S-isomers fit in the A6T7T8/T19A18A17 region in minor groove of B-DNA. Finally, these results indicated that the docking of S-VEN-B-DNA is more stable than R-VEN-B-DNA.

  4. Racemic R,S-venlafaxine hydrochloride-DNA interaction: Experimental and computational evidence

    NASA Astrophysics Data System (ADS)

    Shahabadi, Nahid; Hadidi, Saba; Ghasemian, Zeinab; Taherpour, Avat(Arman)

    2015-06-01

    The interaction of racemic R,S-venlafaxine hydrochloride (rac-VEN) drug with calf thymus deoxyribonucleic acid (ct-DNA) was studied using various physico-chemical techniques and molecular docking at simulated physiological conditions (pH = 7.4). The fluorescence study shows that ct-DNA interacted with rac-VEN and quenched its intrinsic fluorescence in a static quenching process. These results are further supported by UV-Vis spectra. The binding constant of rac-VEN with ct-DNA (0.57 × 104) obtained from the spectroscopic techniques, which is more in keeping with the groove binding with DNA. Furthermore, the competition experiment using Hoechst33258 indicated that rac-VEN may bind to ct-DNA by a minor groove binding mode. In addition, iodide quenching effect on the fluorescence of rac-VEN before and after the interaction with ct-DNA is another evidence to groove binding. The thermodynamic parameters are calculated by van't Hoff equation, which demonstrated that hydrogen bonds and van der Waals interactions played major roles in the binding reaction. Molecular simulation studies carried out by using the AutoDock4 and Spartan10 programs. From the best docking map, we found that R and S-isomers fit in the A6T7T8/T19A18A17 region in minor groove of B-DNA. Finally, these results indicated that the docking of S-VEN-B-DNA is more stable than R-VEN-B-DNA.

  5. Morphological variability in the malaria vector, Anopheles moucheti, is not indicative of speciation: evidences from sympatric south Cameroon populations.

    PubMed

    Antonio-Nkondjio, Christophe; Simard, Frédéric; Cohuet, Anna; Fontenille, Didier

    2002-10-01

    Anopheles moucheti is a major human malaria vector in the vicinity of slow moving rivers in the tropical forests of Central Africa. Morphological variations in natural populations of A. moucheti led to the designation of three morphological forms named A. moucheti moucheti, A. moucheti nigeriensis and A. moucheti bervoetsi. Using allozyme markers, we investigated to which extent morphological and/or geographical populations of A. moucheti were genetically differentiated. Mosquitoes were collected from four villages 20-200 km distant apart in south Cameroon, where specimens from each morphological form were found in sympatry. All populations appeared highly homogenous across both morphological type and geographic location. Significant genetic differentiation was only observed between two locations 150 km apart (F(st)=0.029; P=0.006), while no pairwise F(st) estimate between morphological forms reached statistical significance. Further evidence against any taxonomic value of this morphological classification was provided by direct observation of morphological variation within the progeny of field-collected females from all three types. Single female offspring always belonged to at least two morphologically recognised types and most often, a mixture of all three forms was observed. Our results therefore demonstrate that morphological variability within A. moucheti natural populations is not indicative of speciation. With this respect, restricted migration of individuals across river systems may be a more important factor in shaping population genetic structure of A. moucheti.

  6. Experimental evidence for self-limiting reactive flow through a fractured cement core: implications for time-dependent wellbore leakage.

    PubMed

    Huerta, Nicolas J; Hesse, Marc A; Bryant, Steven L; Strazisar, Brian R; Lopano, Christina L

    2013-01-02

    We present a set of reactive transport experiments in cement fractures. The experiments simulate coupling between flow and reaction when acidic, CO(2)-rich fluids flow along a leaky wellbore. An analog dilute acid with a pH between 2.0 and 3.15 was injected at constant rate between 0.3 and 9.4 cm/s into a fractured cement core. Pressure differential across the core and effluent pH were measured to track flow path evolution, which was analyzed with electron microscopy after injection. In many experiments reaction was restricted within relatively narrow, tortuous channels along the fracture surface. The observations are consistent with coupling between flow and dissolution/precipitation. Injected acid reacts along the fracture surface to leach calcium from cement phases. Ahead of the reaction front, high pH pore fluid mixes with calcium-rich water and induces mineral precipitation. Increases in the pressure differential for most experiments indicate that precipitation can be sufficient to restrict flow. Experimental data from this study combined with published field evidence for mineral precipitation along cemented annuli suggests that leakage of CO(2)-rich fluids along a wellbore may seal the leakage pathway if the initial aperture is small and residence time allows mobilization and precipitation of minerals along the fracture.

  7. Experimental Evidence for Self-Limiting Reactive Flow through a Fractured Cement Core: Implications for Time-Dependent Wellbore Leakage

    SciTech Connect

    Huerta, Nicolas J; Hesse, Marc A; Bryant, Steven L; Strazisar, Brian R; Lopano, Christina L

    2013-01-01

    We present a set of reactive transport experiments in cement fractures. The experiments simulate coupling between flow and reaction when acidic, CO{sub 2}-rich fluids flow along a leaky wellbore. An analog dilute acid with a pH between 2.0 and 3.15 was injected at constant rate between 0.3 and 9.4 cm/s into a fractured cement core. Pressure differential across the core and effluent pH were measured to track flow path evolution, which was analyzed with electron microscopy after injection. In many experiments reaction was restricted within relatively narrow, tortuous channels along the fracture surface. The observations are consistent with coupling between flow and dissolution/precipitation. Injected acid reacts along the fracture surface to leach calcium from cement phases. Ahead of the reaction front, high pH pore fluid mixes with calcium-rich water and induces mineral precipitation. Increases in the pressure differential for most experiments indicate that precipitation can be sufficient to restrict flow. Experimental data from this study combined with published field evidence for mineral precipitation along cemented annuli suggests that leakage of CO{sub 2}-rich fluids along a wellbore may seal the leakage pathway if the initial aperture is small and residence time allows mobilization and precipitation of minerals along the fracture.

  8. Rainbow trout provide the first experimental evidence for adherence to a distinct Strouhal number during animal oscillatory propulsion.

    PubMed

    Nudds, Robert L; John, Emma L; Keen, Adam N; Shiels, Holly A

    2014-07-01

    The relationship between tail (or wing) beat frequency (f(tail)), amplitude (A) and forward velocity (U) in animals using oscillatory propulsion, when moving at a constant cruising speed, converges upon an optimum range of the Strouhal number (St = f(tail) · A/U). Previous work, based on observational data and supported by theory, shows St falling within the broad optimum range (0.2indicate its importance in governing wing or tail kinematics. This study presents the first evidence using an experimental manipulation that supports the importance of maintaining kinematics at a single optimum (or preferred) St. The tail beat kinematics of rainbow trout, Oncorhynchus mykiss, were disturbed by increasing water temperature (T(water)) from 11 ± 1 to 20 ± 1 °C. Elevated T(water) increased f(tail) and decreased A, whilst St at any given U was conserved. St increased with U, driven by concomitant increases in A, whilst f(tail) was unaffected by U. An increase in T(water) also increased basal metabolic costs, but did not affect the incremental increase in metabolic cost with increasing U. Predicted future changes to T(water) of lakes and rivers (5-10 °C over the next 100 years) may not present major locomotory problems to salmonids. © 2014. Published by The Company of Biologists Ltd.

  9. Direct experimental evidence for dissociative photoionization of oxygen molecule via 2Σ(u)(-) ionic "optical dark" state.

    PubMed

    Tang, Xiaofeng; Zhou, Xiaoguo; Wu, Manman; Cai, Yu; Liu, Shilin; Sheng, Liusi

    2012-09-27

    Direct experimental evidence for dissociative photoionization of oxygen molecule via the (2)Σ(u)(-) ionic optical dark state is presented by an investigation using the method of threshold photoelectron-photoion coincidence (TPEPICO) velocity imaging. Besides vibrational progress of the B(2)Σ(g)(-) state, several weak vibrational bands of the (2)Σ(u)(-) ionic optical dark state are observed concomitantly in an excitation energy range of 20.2-21.1 eV. Only O(+) fragments are detected in the whole excitation energy range; therefore, all vibrational bands are completely predissociative. TPEPICO three-dimensional time-sliced velocity images of O(+) fragments dissociated from vibrational state-selected O(2)(+)((2)Σ(u)(-),v(+)) ions are recorded. For the (2)Σ(u)(-)(v(+)=0-3) vibrational states, only the lowest dissociation channel of O(+)((4)S) + O((3)P) is observed. Once the photon energy is slightly increased to the (2)Σ(u)(-)(v(+)=4) level, a new concentric doughnut appears in the image, indicating that the second dissociation channel of O(+)((4)S) + O((1)D) is identified indeed. With the aid of potential energy curves, the dissociative mechanism of O(2)(+) in the (2)Σ(u)(-)(v(+)) state is proposed.

  10. Copper retention, calcium release and ultrastructural evidence indicate specific Cuprolinic Blue uptake and peculiar modifications in mineralizing aortic valves.

    PubMed

    Ortolani, F; Tubaro, F; Petrelli, L; Gandaglia, A; Spina, M; Marchini, M

    2002-01-01

    Previously, reactions with copper phthalocyanines at 0.05 M critical electrolyte concentration were found to cause demineralization in calcifying porcine aortic valves after subdermal implantation in rat, as well as simultaneous visualization of peculiar phthalocyanine-positive layers around cells and cell-derived matrix vesicles. In the present investigation, an appraisal was made of the mechanism and specificity of reactions with Cuprolinic Blue by comparing quantitatively calcium release and copper retention by calcified aortic valves reacted with this phthalocyanine under different critical electrolyte concentration conditions, and the corresponding ultrastructural patterns. It was found that (i) decalcifying properties are inversely proportional to salt molarity; (ii) reactivity to Cuprolinic Blue is critical electrolyte concentration-dependent, since the greatest copper retention occurred in 0.05 M critical electrolyte concentration Cuprolinic Blue-reacted samples, the only ones that also exhibited phthalocyanine-positive layers; (iii) the appearance of phthalocyanine-positive layers depends on Cuprolinic Blue uptake, revealing pericellular clustering of calcium-binding, anionic molecules; and (iv) minor Cuprolinic Blue uptake occurs by residual proteoglycans which still remain in the extracellular matrix after 6-week-long subdermal implantation. The present results indicate that this method is appropriate for the study of mineralized tissues and illustrate peculiar tissue modifications occurring at least in the experimental conditions used here.

  11. Scientific Reasoning in Early and Middle Childhood: The Development of Domain-General Evidence Evaluation, Experimentation, and Hypothesis Generation Skills

    ERIC Educational Resources Information Center

    Piekny, Jeanette; Maehler, Claudia

    2013-01-01

    According to Klahr's (2000, 2005; Klahr & Dunbar, 1988) Scientific Discovery as Dual Search model, inquiry processes require three cognitive components: hypothesis generation, experimentation, and evidence evaluation. The aim of the present study was to investigate (a) when the ability to evaluate perfect covariation, imperfect covariation,…

  12. Glycerol is a suberin monomer. New experimental evidence for an old hypothesis

    PubMed

    Moire; Schmutz; Buchala; Yan; Stark; Ryser

    1999-03-01

    The monomer composition of the esterified part of suberin can be determined using gas chromatography-mass spectroscopy technology and is accordingly believed to be well known. However, evidence was presented recently indicating that the suberin of green cotton (Gossypium hirsutum cv Green Lint) fibers contains substantial amounts of esterified glycerol. This observation is confirmed in the present report by a sodium dodecyl sulfate extraction of membrane lipids and by a developmental study, demonstrating the correlated accumulation of glycerol and established suberin monomers. Corresponding amounts of glycerol also occur in the suberin of the periderm of cotton stems and potato (Solanum tuberosum) tubers. A periderm preparation of wound-healing potato tuber storage parenchyma was further purified by different treatments. As the purification proceeded, the concentration of glycerol increased at about the same rate as that of alpha,omega-alkanedioic acids, the most diagnostic suberin monomers. Therefore, it is proposed that glycerol is a monomer of suberins in general and can cross-link aliphatic and aromatic suberin domains, corresponding to the electron-translucent and electron-opaque suberin lamellae, respectively. This proposal is consistent with the reported dimensions of the electron-translucent suberin lamellae.

  13. Experimental evidence for an absorbing phase transition underlying yielding of a soft glass

    NASA Astrophysics Data System (ADS)

    Nagamanasa, K. Hima; Gokhale, Shreyas; Sood, A. K.; Ganapathy, Rajesh

    2014-03-01

    A characteristic feature of solids ranging from foams to atomic crystals is the existence of a yield point, which marks the threshold stress beyond which a material undergoes plastic deformation. In hard materials, it is well-known that local yield events occur collectively in the form of intermittent avalanches. The avalanche size distributions exhibit power-law scaling indicating the presence of self-organized criticality. These observations led to predictions of a non-equilibrium phase transition at the yield point. By contrast, for soft solids like gels and dense suspensions, no such predictions exist. In the present work, by combining particle scale imaging with bulk rheology, we provide a direct evidence for a non-equilibrium phase transition governing yielding of an archetypal soft solid - a colloidal glass. The order parameter and the relaxation time exponents revealed that yielding is an absorbing phase transition that belongs to the conserved directed percolation universality class. We also identified a growing length scale associated with clusters of particles with high Debye-Waller factor. Our findings highlight the importance of correlations between local yield events and may well stimulate the development of a unified description of yielding of soft solids.

  14. Glycerol Is a Suberin Monomer. New Experimental Evidence for an Old Hypothesis1

    PubMed Central

    Moire, Laurence; Schmutz, Alain; Buchala, Antony; Yan, Bin; Stark, Ruth E.; Ryser, Ulrich

    1999-01-01

    The monomer composition of the esterified part of suberin can be determined using gas chromatography-mass spectroscopy technology and is accordingly believed to be well known. However, evidence was presented recently indicating that the suberin of green cotton (Gossypium hirsutum cv Green Lint) fibers contains substantial amounts of esterified glycerol. This observation is confirmed in the present report by a sodium dodecyl sulfate extraction of membrane lipids and by a developmental study, demonstrating the correlated accumulation of glycerol and established suberin monomers. Corresponding amounts of glycerol also occur in the suberin of the periderm of cotton stems and potato (Solanum tuberosum) tubers. A periderm preparation of wound-healing potato tuber storage parenchyma was further purified by different treatments. As the purification proceeded, the concentration of glycerol increased at about the same rate as that of α,ω-alkanedioic acids, the most diagnostic suberin monomers. Therefore, it is proposed that glycerol is a monomer of suberins in general and can cross-link aliphatic and aromatic suberin domains, corresponding to the electron-translucent and electron-opaque suberin lamellae, respectively. This proposal is consistent with the reported dimensions of the electron-translucent suberin lamellae. PMID:10069853

  15. Is there an association between hypercholesterolemia and depression? Behavioral evidence from the LDLr(-/-) mouse experimental model.

    PubMed

    Engel, Daiane Fátima; de Oliveira, Jade; Lopes, Jadna Bogado; Santos, Danúbia Bonfanti; Moreira, Eduardo Luiz Gasnhar; Farina, Marcelo; Rodrigues, Ana Lúcia S; de Souza Brocardo, Patricia; de Bem, Andreza Fabro

    2016-09-15

    Although epidemiological studies have reported an association between hypercholesterolemia and mood disorders, there is a lack of data regarding depressive-like behavior in animal models of hypercholesterolemia. To address these questions, we assessed depressive-like behavior and hippocampal and cortical monoaminergic metabolism in three-month-old, low-density lipoprotein receptor knockout (LDLr(-/-)) and C57BL/6 wild-type mice. The LDLr(-/-) mice exhibited depressive-like behavior in the sucrose preference test, splash test, and tail suspension test. Increased monoamine oxidase (MAO) A and B activity was evidenced in the hippocampus of LDLr(-/-) mice. Furthermore, to address whether or not cholesterol modulates MAO activity, we exposed SH-SY5Y human neuroblastoma cells to human isolated low-density lipoprotein (LDL). Notably, LDL increased the activity of MAO-A and stimulated the reactive species generation in vitro. These findings indicate that depressive-like behavior in hypercholesterolemic mice is accompanied by alterations in the monoaminergic metabolism, providing new evidence about the association between hypercholesterolemia and depression. Copyright © 2016. Published by Elsevier B.V.

  16. No Experimental Evidence for Sneaking in a West African Cichlid Fish with Extremely Long Sperm

    PubMed Central

    Langen, Kathrin; Thünken, Timo; Bakker, Theo C. M.

    2013-01-01

    Alternative reproductive tactics are widespread in fishes, increasing the potential for sperm competition. Sperm competition has enormous impact on both variation in sperm numbers and sperm size. In cichlids, the sperm competition risk is very divergent and longer sperm are usually interpreted as adaptation to sperm competition. Here we examined whether sneaking tactics exist in Pelvicachromis taeniatus, a socially monogamous cichlid with biparental brood care from West Africa. The small testis indicates low gonadal investment which is typical for genetically monogamous species. In contrast, sperm length with up to 85 μm is extraordinarily long. We examined the reproductive behaviour of ten groups with a male-biased sex ratio under semi-natural conditions via continuous video recording. We recorded spawning site preferences and correlates of reproductive success and conducted paternity tests using microsatellites. Safe breeding sites that could be successfully defended were preferred. All offspring could be assigned to their parents and no multiple paternities were detected. Body size of spawning pairs predicted their spawning probability and offspring hatching rate suggesting benefits from mating with large individuals. Our study suggests low risk of sperm competition under the given conditions in P. taeniatus and thus first evidence for genetic monogamy in a substrate breeding cichlid. PMID:24386589

  17. User preferences and willingness to pay for safe drinking water: Experimental evidence from rural Tanzania.

    PubMed

    Burt, Zachary; Njee, Robert M; Mbatia, Yolanda; Msimbe, Veritas; Brown, Joe; Clasen, Thomas F; Malebo, Hamisi M; Ray, Isha

    2017-01-01

    Almost half of all deaths from drinking microbiologically unsafe water occur in Sub-Saharan Africa. Household water treatment and safe storage (HWTS) systems, when consistently used, can provide safer drinking water and improve health. Social marketing to increase adoption and use of HWTS depends both on the prices of and preferences for these systems. This study included 556 households from rural Tanzania across two low-income districts with low-quality water sources. Over 9 months in 2012 and 2013, we experimentally evaluated consumer preferences for six "low-cost" HWTS options, including boiling, through an ordinal ranking protocol. We estimated consumers' willingness to pay (WTP) for these options, using a modified auction. We allowed respondents to pay for the durable HWTS systems with cash, chickens or mobile money; a significant minority chose chickens as payment. Overall, our participants favored boiling, the ceramic pot filter and, where water was turbid, PuR™ (a combined flocculant-disinfectant). The revealed WTP for all products was far below retail prices, indicating that significant scale-up may need significant subsidies. Our work will inform programs and policies aimed at scaling up HWTS to improve the health of resource-constrained communities that must rely on poor-quality, and sometimes turbid, drinking water sources.

  18. Experimental Evidence of Classical Conditioning and Microscopic Engrams in an Electroconductive Material

    PubMed Central

    Karbowski, Lukasz M.; Persinger, Michael A.

    2016-01-01

    Synthetic experimental substrates are indispensable tools which can allow researchers to model biological processes non-invasively in three-dimensional space. In this study, we investigated the capacities of an electroconductive material whose properties converge upon those of the brain. An electrically conductive material composed of carbohydrates, proteins, fats, ions, water, and trace amounts of other organic compounds and minerals was classically conditioned as inferred by electrophysiological measurements. Spectral densities evoked during the display of a conditioned stimulus (CS) probe were strongly congruent with those displayed during the conditioned-unconditioned stimulus pairing (CS-UCS). The neutral stimulus consisted of the pulsed light from a LED. The unconditioned stimulus was an alternating current. Interstimulus intervals >130 ms did not result in conditioned responses. Microscopic analysis of the chemically-fixed substratum revealed 10–200 μm wide ‘vessel structures’ within samples exposed to a stimulus. Greater complexity (increased fractal dimensions) was clearly discernable by light microscopy for stained sections of fixed samples that had been conditioned compared to various controls. The denser pixels indicated greater concentration of stain and increased canalization. Implications for learning and memory formation are discussed. PMID:27764215

  19. Passionate love and relationship thinkers: experimental evidence for acute cortisol elevations in women.

    PubMed

    Loving, Timothy J; Crockett, Erin E; Paxson, Aubri A

    2009-07-01

    We assessed the impact of an individual difference variable, relationship-focused thinking, on women's acute salivary cortisol responses during and after a guided imagery task. Specifically, 29 healthy women, all of whom were experiencing high levels of passionate love, but varied on levels of relationship-focused thinking, were assigned to one of two experimental conditions: a partner reflection condition or a cross-sex friend reflection condition. Results indicated that women experiencing passionate love evidenced increased cortisol levels when asked to reflect on their romantic partner and relationship relative to women asked to reflect on a cross-sex friendship, but this difference was particularly pronounced and relatively long-lasting for those women characterized by a high amount of relationship-focused thinking. Our study significantly expands extant work on the passionate love-cortisol link by isolating the impact of a specific psychological variable, relationship-focused thinking, on the physiological experience of falling in love. We believe our work highlights the advances that can be made when established work in the close relationships and neuroendocrine fields are integrated.

  20. Formation of Quartz-Carbonate Veins: Evidence From Experimental Supercritical Carbon Dioxide-Brine-Rock System

    NASA Astrophysics Data System (ADS)

    Janecky, D. R.; Kaszuba, J. P.

    2003-12-01

    precipitation from relatively small volumes of total fluid, with coupled increases in pH and mineral stability. The doubling of silica concentration in the experimental system containing acidic brine and supercritical carbon dioxide indicates that precipitation of silica can occur in parallel to carbonate minerals when pH increases. Emplacement of silica super-saturated brine into a rock-dominated reaction system buffered to more neutral pH conditions may enhance precipitation of quartz, chalcedony, or amorphous silica as veins or cements, depending on the permeability structure of the host rock. Phase separation or loss of carbon dioxide with decreasing pressure can substantially shift pH upwards, with potential for creating massive vein or scale formation.

  1. Assessing the impact of human trampling on vegetation: a systematic review and meta-analysis of experimental evidence.

    PubMed

    Pescott, Oliver L; Stewart, Gavin B

    2014-01-01

    Vegetation trampling resulting from recreation can adversely impact natural habitats, leading to the loss of vegetation and the degradation of plant communities. A considerable primary literature exists on this topic, therefore it is important to assess whether this accumulated evidence can be used to reach general conclusions concerning vegetation vulnerability to inform conservation management decisions. Experimental trampling studies on a global scale were retrieved using a systematic review methodology and synthesised using random effects meta-analysis. The relationships between vegetation recovery and each of initial vegetation resistance, trampling intensity, time for recovery, Raunkiaer life-form (perennating bud position), and habitat were tested using random effects multiple meta-regressions and subgroup analyses. The systematic search yielded 304 studies; of these, nine reported relevant randomized controlled experiments, providing 188 vegetation recovery effect sizes for analysis. The synthesis indicated there was significant heterogeneity in the impact of trampling on vegetation recovery. This was related to resistance and recovery time, and the interactions of these variables with Raunkiaer life-form, but was not strongly dependent on the intensity of the trampling experienced. The available evidence suggests that vegetation dominated by hemicryptophytes and geophytes recovers from trampling to a greater extent than vegetation dominated by other life-forms. Variation in effect within the chamaephyte, hemicryptophyte and geophyte life-form sub-groups was also explained by the initial resistance of vegetation to trampling, but not by trampling intensity. Intrinsic properties of plant communities appear to be the most important factors determining the response of vegetation to trampling disturbance. Specifically, the dominant Raunkiaer life-form of a plant community accounts for more variation in the resilience of communities to trampling than the

  2. Individual benefits of nestling begging: experimental evidence for an immediate effect, but no evidence for a delayed effect.

    PubMed

    Lessells, C Kate M; Riebel, Katharina; Draganoiu, Tudor Ion

    2011-06-23

    The evolutionary stability of honest signalling by offspring is thought to require that begging displays be costly, so the costs and benefits of begging--and whether they are experienced individually or by the whole brood--are crucial to understanding the evolution of begging behaviour. Begging is known to have immediate individual benefits (parents distribute more food to intensely begging individuals) and delayed brood benefits (parents increase provisioning rate to the brood), but the possibility of delayed individual benefits (previous begging affects the current distribution of food) has rarely, if ever, been researched. We did this using playback of great tit Parus major chick begging and a control sound from either side of the nest. Male parents fed chicks close to the speaker more when great tit chick begging, but not other stimuli, was played back. In contrast, there was no effect of playback at the previous visit on the chicks that male parents fed. We have thus demonstrated an immediate individual benefit to begging, but found no evidence of a delayed individual benefit in this species.

  3. Theoretical and experimental evidence indicates that there is no detectable auxin gradient in the angiosperm female gametophyte.

    PubMed

    Lituiev, Dmytro S; Krohn, Nádia G; Müller, Bruno; Jackson, David; Hellriegel, Barbara; Dresselhaus, Thomas; Grossniklaus, Ueli

    2013-11-01

    The plant life cycle alternates between a diploid sporophytic and a haploid gametophytic generation. The female gametophyte (FG) of flowering plants is typically formed through three syncytial mitoses, followed by cellularisation that forms seven cells belonging to four cell types. The specification of cell fates in the FG has been suggested to depend on positional information provided by an intrinsic auxin concentration gradient. The goal of this study was to develop mathematical models that explain the formation of this gradient in a syncytium. Two factors were proposed to contribute to the maintenance of the auxin gradient in Arabidopsis FGs: polar influx at early stages and localised auxin synthesis at later stages. However, no gradient could be generated using classical, one-dimensional theoretical models under these assumptions. Thus, we tested other hypotheses, including spatial confinement by the large central vacuole, background efflux and localised degradation, and investigated the robustness of cell specification under different parameters and assumptions. None of the models led to the generation of an auxin gradient that was steep enough to allow sufficiently robust patterning. This led us to re-examine the response to an auxin gradient in developing FGs using various auxin reporters, including a novel degron-based reporter system. In agreement with the predictions of our models, auxin responses were not detectable within the FG of Arabidopsis or maize, suggesting that the effects of manipulating auxin production and response on cell fate determination might be indirect.

  4. On the early emergence of reverse transcription: theoretical basis and experimental evidence

    NASA Technical Reports Server (NTRS)

    Lazcano, A.; Valverde, V.; Hernandez, G.; Gariglio, P.; Fox, G. E.; Oro, J.

    1992-01-01

    Reverse transcriptase (RT) was first discovered as an essential catalyst in the biological cycle of retroviruses. However, in the past years evidence has accumulated showing that RTs are involved in a surprisingly large number of RNA-mediated transpositional events that include both viral and nonviral genetic entities. Although it is probable that some RT-bearing genetic elements like the different types of AIDS viruses and the mammalian LINE family have arisen in recent geological times, the possibility that reverse transcription first took place in the early Archean is supported by (1) the hypothesis that RNA preceded DNA as cellular genetic material; (2) the existence of homologous regions of the subunit tau of the E. coli DNA polymerase III with the simian immunodeficiency virus RT, the hepatitis B virus RT, and the beta' subunit of the E. coli RNA polymerase (McHenry et al. 1988); (3) the presence of several conserved motifs, including a 14-amino-acid segment that consists of an Asp-Asp pair flanked by hydrophobic amino acids, which are found in all RTs and in most cellular and viral RNA polymerases. However, whether extant RTs descend from the primitive polymerase involved in the RNA-to-DNA transition remains unproven. Substrate specificity of the AMV and HIV-1 RTs can be modified in the presence of Mn2+, a cation which allows them to add ribonucleotides to an oligo (dG) primer in a template-dependent reaction. This change in specificity is comparable to that observed under similar conditions in other nucleic acid polymerases. This experimentally induced change in RT substrate specificity may explain previous observations on the misincorporation of ribonucleotides by the Maloney murine sarcoma virus RT in the minus and plus DNA of this retrovirus (Chen and Temin 1980). Our results also suggest that HIV-infected macrophages and T-cell cells may contain mixed polynucleotides containing both ribo- and deoxyribonucleotides. The evolutionary significance of these

  5. On the early emergence of reverse transcription: theoretical basis and experimental evidence

    NASA Technical Reports Server (NTRS)

    Lazcano, A.; Valverde, V.; Hernandez, G.; Gariglio, P.; Fox, G. E.; Oro, J.

    1992-01-01

    Reverse transcriptase (RT) was first discovered as an essential catalyst in the biological cycle of retroviruses. However, in the past years evidence has accumulated showing that RTs are involved in a surprisingly large number of RNA-mediated transpositional events that include both viral and nonviral genetic entities. Although it is probable that some RT-bearing genetic elements like the different types of AIDS viruses and the mammalian LINE family have arisen in recent geological times, the possibility that reverse transcription first took place in the early Archean is supported by (1) the hypothesis that RNA preceded DNA as cellular genetic material; (2) the existence of homologous regions of the subunit tau of the E. coli DNA polymerase III with the simian immunodeficiency virus RT, the hepatitis B virus RT, and the beta' subunit of the E. coli RNA polymerase (McHenry et al. 1988); (3) the presence of several conserved motifs, including a 14-amino-acid segment that consists of an Asp-Asp pair flanked by hydrophobic amino acids, which are found in all RTs and in most cellular and viral RNA polymerases. However, whether extant RTs descend from the primitive polymerase involved in the RNA-to-DNA transition remains unproven. Substrate specificity of the AMV and HIV-1 RTs can be modified in the presence of Mn2+, a cation which allows them to add ribonucleotides to an oligo (dG) primer in a template-dependent reaction. This change in specificity is comparable to that observed under similar conditions in other nucleic acid polymerases. This experimentally induced change in RT substrate specificity may explain previous observations on the misincorporation of ribonucleotides by the Maloney murine sarcoma virus RT in the minus and plus DNA of this retrovirus (Chen and Temin 1980). Our results also suggest that HIV-infected macrophages and T-cell cells may contain mixed polynucleotides containing both ribo- and deoxyribonucleotides. The evolutionary significance of these

  6. Differential Activities of the Two Closely Related Withanolides, Withaferin A and Withanone: Bioinformatics and Experimental Evidences

    PubMed Central

    Manjunath, Kavyashree; Uthayakumar, M.; Kanaujia, Shankar P.; Kaul, Sunil C.; Sekar, Kanagaraj; Wadhwa, Renu

    2012-01-01

    Background and Purpose Withanolides are naturally occurring chemical compounds. They are secondary metabolites produced via oxidation of steroids and structurally consist of a steroid-backbone bound to a lactone or its derivatives. They are known to protect plants against herbivores and have medicinal value including anti-inflammation, anti-cancer, adaptogenic and anti-oxidant effects. Withaferin A (Wi-A) and Withanone (Wi-N) are two structurally similar withanolides isolated from Withania somnifera, also known as Ashwagandha in Indian Ayurvedic medicine. Ashwagandha alcoholic leaf extract (i-Extract), rich in Wi-N, was shown to kill cancer cells selectively. Furthermore, the two closely related purified phytochemicals, Wi-A and Wi-N, showed differential activity in normal and cancer human cells in vitro and in vivo. We had earlier identified several genes involved in cytotoxicity of i-Extract in human cancer cells by loss-of-function assays using either siRNA or randomized ribozyme library. Methodology/Principal Findings In the present study, we have employed bioinformatics tools on four genes, i.e., mortalin, p53, p21 and Nrf2, identified by loss-of-function screenings. We examined the docking efficacy of Wi-N and Wi-A to each of the four targets and found that the two closely related phytochemicals have differential binding properties to the selected cellular targets that can potentially instigate differential molecular effects. We validated these findings by undertaking parallel experiments on specific gene responses to either Wi-N or Wi-A in human normal and cancer cells. We demonstrate that Wi-A that binds strongly to the selected targets acts as a strong cytotoxic agent both for normal and cancer cells. Wi-N, on the other hand, has a weak binding to the targets; it showed milder cytotoxicity towards cancer cells and was safe for normal cells. The present molecular docking analyses and experimental evidence revealed important insights to the use of Wi-A and

  7. Metal loading effect on rare earth element binding to humic acid: Experimental and modelling evidence

    NASA Astrophysics Data System (ADS)

    Marsac, Rémi; Davranche, Mélanie; Gruau, Gérard; Dia, Aline

    2010-03-01

    The effect of metal loading on the binding of rare earth elements (REE) to humic acid (HA) was studied by combining ultrafiltration and Inductively Coupled Plasma Mass Spectrometry techniques. REE-HA complexation experiments were performed at pH 3 for REE/C molar ratios ranging from ca 4 × 10 -4 to 2.7 × 10 -2. Results show that the relative amount of REE bound to HA strongly increases with decreasing REE/C. A middle-REE (MREE) downward concavity is shown by patterns at high metal loading, whereas patterns at low metal loading display a regular increase from La to Lu. Humic Ion Model VI modelling are close to the experimental data variations, provided that (i) the ΔLK 2 parameter (i.e. the Model VI parameter taken into account the presence of strong but low density binding sites) is allowed to increase regularly from La to Lu (from 1.1 to 2.1) and (ii) the published log KMA values (i.e. the REE-HA binding constants specific to Model VI) are slightly modified, in particular with respect to heavy REE. Modelling approach provided evidence that logKdREE patterns with varying REE/C likely arises because REE binding to HA occurs through two types of binding sites in different density: (i) a few strong sites that preferentially complex the heavy REE and thus control the logKdREE atterns at low REE/C; (ii) a larger amount of weaker binding sites that preferentially complex the middle-REE and thus control the logKdREE pattern at high REE/C. Hence, metal loading exerts a major effect on HA-mediated REE binding, which could explain the diversity of published conditional constants for REE binding with HA. A literature survey suggests that the few strong sites activated at low REE/C could be multidentate carboxylic sites, or perhaps N-, or P-functional groups. Finally, an examination of the literature field data proposed that the described loading effect could account for much of the variation in REE patterns observed in natural organic-rich waters (DOC > 5 mg L -1 and 4

  8. Experimental evidence for limited vocal recognition in a wild primate: implications for the social complexity hypothesis.

    PubMed

    Bergman, Thore J

    2010-10-07

    Although monitoring social information is a key aspect of the social complexity hypothesis, surprisingly little work has compared social knowledge across different species of wild animals. In the present study, I use playback experiments to test for individual recognition in wild male geladas (Theropithecus gelada) to compare with published accounts of social knowledge in chacma baboons (Papio ursinus). Geladas and baboons are closely related primates living in socially complex groups that differ dramatically in group size-geladas routinely associate with more than 10 times the number of conspecifics than do baboons. Using grunts from non-rival males to simulate approaches, I examined the strength of a subject male's response when the 'approach' was from the direction of (i) non-rival males (control), or (ii) rival males (a more salient stimulus if playback grunts are not recognized by the subject). I compared responses separately based on the degree of social overlap between the caller and the subject. Responses indicate that male geladas, unlike baboons, do not use vocalizations to recognize all of the individuals they regularly encounter. This represents, to my knowledge, the first documented evidence of 'missing' social knowledge in a natural primate population. The sharp distinction between baboons and geladas suggests that geladas are either unable or unmotivated to keep track of the individual identity of other males in their multi-level society-even males with whom they have a large degree of social overlap. Thus, these results are consistent with the central assumption of the social complexity hypothesis that social cognition is costly.

  9. Spatiotemporal mapping of matrix remodelling and evidence of in situ elastogenesis in experimental abdominal aortic aneurysms.

    PubMed

    Deb, Partha Pratim; Ramamurthi, Anand

    2017-01-01

    Spatiotemporal changes in the extracellular matrix (ECM) were studied within abdominal aortic aneurysms (AAAs) generated in rats via elastase infusion. At 7, 14 and 21 days post-induction, AAA tissues were divided into proximal, mid- and distal regions, based on their location relative to the renal arteries and the region of maximal aortic diameter. Wall thicknesses differed significantly between the AAA spatial regions, initially increasing due to positive matrix remodelling and then decreasing due to wall thinning and compaction of matrix as the disease progressed. Histological images analysed using custom segmentation tools indicated significant differences in ECM composition and structure vs healthy tissue, and in the extent and nature of matrix remodelling between the AAA spatial regions. Histology and immunofluorescence (IF) labelling provided evidence of neointimal AAA remodelling, characterized by presence of elastin-containing fibres. This remodelling was effected by smooth muscle α-actin-positive neointimal cells, which transmission electron microscopy (TEM) showed to differ morphologically from medial SMCs. TEM of the neointima further showed the presence of elongated deposits of amorphous elastin and the presence of nascent, but not mature, elastic fibres. These structures appeared to be deficient in at least one microfibrillar component, fibrillin-1, which is critical to mature elastic fibre assembly. The substantial production of elastin and elastic fibre-like structures that we observed in the AAA neointima, which was not observed elsewhere within AAA tissues, provides a unique opportunity to capitalize on this autoregenerative phenomenon and direct it from the standpoint of matrix organization towards restoring healthy aortic matrix structure, mechanics and function. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

  10. Feeling the past: the absence of experimental evidence for anomalous retroactive influences on text processing.

    PubMed

    Traxler, Matthew J; Foss, Donald J; Podali, Ruchira; Zirnstein, Megan

    2012-11-01

    In two self-paced reading experiments, we investigated the hypothesis that information moves backward in time to influence prior behaviors (Bem Journal of Personality and Social Psychology 100:407-425, 2011a). In two of Bem's experiments, words were presented after target pictures in a pleasantness judgment task. In a condition in which the words were consistent with the emotional valence of the picture, reaction times to the pictures were significantly shorter , as compared with a condition in which the words were inconsistent with the emotional valence of the picture. Bem Journal of Personality and Social Psychology 100:407-425, (2011a) interpreted these results as showing a "retroactive priming" effect resulting from precognition. To test the precognition hypothesis, we adapted a standard repetition priming paradigm from psycholinguistics. In the experiments, participants read a set of texts. In one condition, the participants read the same text twice. In other conditions, participants read two different texts. The precognition hypothesis predicts that readers who encounter the same text twice will experience reductions in processing load during their first encounter with the text. Hence, these readers' average reading times should be shorter than those of readers who encounter the target text only once. Our results indicated that readers processed the target text faster the second time they read it. Also, their reading times decreased as their experience with the self-paced reading procedure increased. However, participants read the target text equally quickly during their initial encounter with the text, whether or not the text was subsequently repeated. Thus, the experiments demonstrated normal repetition priming and practice effects but offered no evidence for retroactive influences on text processing.

  11. Experimental evidence for healing during stick-slip at the bases of ice streams

    NASA Astrophysics Data System (ADS)

    Zoet, Lucas K.; Iverson, Neal R.

    2016-04-01

    The Whillians Ice Stream has twice daily stick-slip events of ca. 50 cm with a maximum inter-event time of ca. 60,000 s. In order for stick-slip phenomena to occur under rate and state friction, two conditions need to be met: 1) A rate-weakening material at the interface, so that a nucleated slip perturbance can be propagated and 2) a material capable of healing (i.e., becoming stronger) when stationary, so that stress can be recharged during hold periods between ruptures. Although rate weakening has been experimentally demonstrated for some basal tills, experimental data relevant to glacier slip that bear on healing have been absent. Without an understanding of the healing mechanisms active at the beds of ice streams, models of the mechanics of ice stream stick-slip or ice stream shut-down will be inadequately informed. We investigated healing mechanisms with slide-hold-slide experiments, a technique common in rock mechanics, using two different ring shear apparatuses. In one set of experiments till alone was sheared, while in another set ice at its melting temperature was slid over till. These two kinds of experiments allowed for the isolation of mechanisms active at ice-till interface from those within the till. In all experiments sliding velocity was ca. 345 m/yr, and effective stress was ca. 150 kPa. Once steady-state sliding friction, μss, was attained, sliding was stopped and the materials were held in stationary contact for a given duration. When sliding was reinitiated, slip resistance initially rose above the previous μss value to a peak friction, μpeak, before returning to μss. The difference between μss and μpeak, Δμ, was then calculated. For each subsequent hold, the duration of stationary contact was increased logarithmically (100, 1,000, 10,000 and 100,000 s) until the maximum hold duration was attained. From the relationship between hold time and Δμ, a healing rate was calculated. Results from both sets of experiment indicate that

  12. Experimental infection of mice with hamster parvovirus: evidence for interspecies transmission of mouse parvovirus 3.

    PubMed

    Christie, Rachel D; Marcus, Emily C; Wagner, April M; Besselsen, David G

    2010-04-01

    Hamster parvovirus (HaPV) was isolated 2 decades ago from hamsters with clinical signs similar to those induced in hamsters experimentally infected with other rodent parvoviruses. Genetically, HaPV is most closely related to mouse parvovirus (MPV), which induces subclinical infection in mice. A novel MPV strain, MPV3, was detected recently in naturally infected mice, and genomic sequence analysis indicates that MPV3 is almost identical to HaPV. The goal of the present studies was to examine the infectivity of HaPV in mice. Neonatal and weanling mice of several mouse strains were inoculated with HaPV. Tissues, excretions, and sera were harvested at 1, 2, 4, and 8 wk after inoculation and evaluated by quantitative PCR and serologic assays specific for HaPV. Quantitative PCR detected viral DNA quantities that greatly exceeded the quantity of virus in inocula in multiple tissues of infected mice. Seroconversion to both nonstructural and structural viral proteins was detected in most immunocompetent mice 2 or more weeks after inoculation with HaPV. In neonatal SCID mice, viral transcripts were detected in lymphoid tissues by RT-PCR and viral DNA was detected in feces by quantitative PCR at 8 wk after inoculation. No clinical signs, gross, or histologic lesions were observed. These findings are similar to those observed in mice infected with MPV. These data support the hypothesis that HaPV and MPV3 are likely variants of the same viral species, for which the mouse is the natural rodent host with rare interspecies transmission to the hamster.

  13. Experimental Infection of Mice with Hamster Parvovirus: Evidence for Interspecies Transmission of Mouse Parvovirus 3

    PubMed Central

    Christie, Rachel D; Marcus, Emily C; Wagner, April M; Besselsen, David G

    2010-01-01

    Hamster parvovirus (HaPV) was isolated 2 decades ago from hamsters with clinical signs similar to those induced in hamsters experimentally infected with other rodent parvoviruses. Genetically, HaPV is most closely related to mouse parvovirus (MPV), which induces subclinical infection in mice. A novel MPV strain, MPV3, was detected recently in naturally infected mice, and genomic sequence analysis indicates that MPV3 is almost identical to HaPV. The goal of the present studies was to examine the infectivity of HaPV in mice. Neonatal and weanling mice of several mouse strains were inoculated with HaPV. Tissues, excretions, and sera were harvested at 1, 2, 4, and 8 wk after inoculation and evaluated by quantitative PCR and serologic assays specific for HaPV. Quantitative PCR detected viral DNA quantities that greatly exceeded the quantity of virus in inocula in multiple tissues of infected mice. Seroconversion to both nonstructural and structural viral proteins was detected in most immunocompetent mice 2 or more weeks after inoculation with HaPV. In neonatal SCID mice, viral transcripts were detected in lymphoid tissues by RT-PCR and viral DNA was detected in feces by quantitative PCR at 8 wk after inoculation. No clinical signs, gross, or histologic lesions were observed. These findings are similar to those observed in mice infected with MPV. These data support the hypothesis that HaPV and MPV3 are likely variants of the same viral species, for which the mouse is the natural rodent host with rare interspecies transmission to the hamster. PMID:20412687

  14. Experimental evidence of early costs of reproduction in conspecific viviparous and oviparous lizards.

    PubMed

    Bleu, J; Heulin, B; Haussy, C; Meylan, S; Massot, M

    2012-07-01

    Reproduction entails costs, and disentangling the relative importance of each stage of the reproductive cycle may be important to assess the costs and benefits of different reproductive strategies. We studied the early costs of reproduction in oviparous and viviparous lizard females of the bimodal reproductive species Zootoca vivipara. Egg retention time in oviparous females is approximately one-third of the time in viviparous females. We compared the vitellogenesis and egg retention stages that are common to both reproductive modes. Precisely, we monitored the thermoregulatory behaviour, the weight gain and the immunocompetence of the females. Moreover, we injected an antigen in half of the females (immune challenge) to study the trade-offs between reproductive mode and immune performance and between different components of the immune system. Finally, we experimentally induced parturition in viviparous females at the time of egg laying in oviparous females. Oviparous and viviparous females did not show strong differences in response to the immune challenge. However, viviparous females spent more time thermoregulating while partially hidden and gained more weight than oviparous females. The greater weight gain indicates that the initial period of egg retention is less costly for viviparous than for oviparous females or that viviparous females are able to save and accumulate energy at this period. This energy may be used by viviparous females to cope with the subsequent costs of the last two-third of the gestation. Such an ability to compensate the higher costs of a longer egg retention period may account for the frequent evolution of viviparity in squamate reptiles. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

  15. Fossil bryophytes as recorders of ancient CO2 levels: Experimental evidence and a Cretaceous case study

    NASA Astrophysics Data System (ADS)

    Fletcher, Benjamin J.; Beerling, David J.; Brentnall, Stuart J.; Royer, Dana L.

    2005-09-01

    Biological and geochemical CO2 proxies provide critical constraints on understanding the role of atmospheric CO2 in driving climate change during Earth history. As no single existing CO2 proxy is without its limitations, there is a clear need for new approaches to reconstructing past CO2 concentrations. Here we develop a new pre-Quaternary CO2 proxy based on the stable carbon isotope composition (δ13C) of astomatous land plants. In a series of CO2-controlled laboratory experiments, we show that the carbon isotope discrimination (Δ13C) of a range of bryophyte (liverwort and moss) species increases with atmospheric CO2 across the range 375 to 6000 ppm. Separate experiments establish that variations in growth temperature, water content and substrate type have minor impacts on the Δ13C of liverworts but not mosses, indicating the greater potential of liverworts to faithfully record past variations in CO2. A mechanistic model for calculating past CO2 concentrations from bryophyte Δ13C (White et al., 1994) is extended and calibrated using our experimental results. The potential for fossil liverworts to record past CO2 changes is investigated by analyzing the δ13C of specimens collected from Alexander Island, Antarctica dating to the "greenhouse" world of the mid-Cretaceous. Our analysis and isotopic model yield mid-Cretaceous CO2 concentrations of 1000-1400 ppm, in general agreement with independent proxy data and long-term carbon cycle models. The exceptionally long evolutionary history of bryophytes offers the possibility of reconstructing CO2 concentrations back to the mid-Ordovician, pre-dating all currently used quantitative CO2 proxies.

  16. Quasi-experimental Study Designs Series - Paper 12: Strengthening Global Capacity for Evidence Synthesis of Quasi-experimental Health Systems Research.

    PubMed

    Rockers, Peter C; Tugwell, Peter; Grimshaw, Jeremy; Oliver, Sandy; Atun, Rifat; Røttingen, John-Arne; Fretheim, Atle; Ranson, M Kent; Daniels, Karen; Luiza, Vera Lucia; Bärnighausen, Till

    2017-03-28

    Evidence from quasi-experimental studies is often excluded from systematic reviews of health systems research despite the fact that such studies can provide strong causal evidence when well-conducted. This article discusses global coordination of efforts to institutionalize the inclusion of causal evidence from quasi-experiments in systematic reviews of health systems research. In particular, we are concerned with identifying opportunities for strengthening capacity at the global- and local-level for implementing protocols necessary to ensure that reviews that include quasi-experiments are consistently of the highest quality. We first describe the current state of the global infrastructure that facilitates the production of systematic reviews of health systems research. We identify five important types of actors operating within this infrastructure: review authors; synthesis collaborations that facilitate the review process; synthesis interest groups that supplement the work of the larger collaborations; review funders; and end users, including policymakers. Then, we examine opportunities for intervening to build the capacity of each type of actor to support the inclusion of quasi-experiments in reviews. Lastly, we suggest practical next steps for proceeding with capacity building efforts. Due to the complexity and relative nascence of the field, we recommend a carefully planned and executed approach to strengthening global capacity for the inclusion of quasi-experimental studies in systematic reviews.

  17. An evidence-update on the prospective relationship between childhood sedentary behaviour and biomedical health indicators: a systematic review and meta-analysis.

    PubMed

    van Ekris, E; Altenburg, T M; Singh, A S; Proper, K I; Heymans, M W; Chinapaw, M J M

    2016-09-01

    Evidence for adverse health effects of excessive sedentary behaviour in children is predominantly based on cross-sectional studies, measuring TV viewing as proxy for sedentary behaviour. This systematic review and meta-analysis summarizes the evidence on the prospective relationship between childhood sedentary behaviour and biomedical health indicators, overall and stratified by type of sedentary behaviour (TV viewing, computer use/games, screen time and objective sedentary time). PubMed, EMBASE, PsycINFO and Cochrane were systematically searched till January 2015. Methodological quality of all included studies was scored, and a best evidence synthesis was applied. We included 109 studies of which 19 were of high quality. We found moderate-to-strong evidence for a relationship of overall sedentary time with some anthropometrics (overweight/obesity, weight-for-height), one cardiometabolic biomarker (HDL-cholesterol) and some fitness indicators (fitness, being unfit). For other health indicators, we found no convincing evidence because of inconsistent or non-significant findings. The evidence varied by type of sedentary behaviour. The meta-analysis indicated that each additional baseline hour of TV viewing (β = 0.01, 95%CI = [-0.002; 0.02]) or computer use (β = 0.00, 95%CI = [-0.004; 0.01]) per day was not significantly related with BMI at follow-up. We conclude that the evidence for a prospective relationship between childhood sedentary behaviour and biomedical health is in general unconvincing.

  18. Nurse staffing and system integration and change indicators in acute care hospitals: evidence from a balanced scorecard.

    PubMed

    McGillis Hall, Linda; Peterson, Jessica; Baker, G Ross; Brown, Adalsteinn D; Pink, George H; McKillop, Ian; Daniel, Imtiaz; Pedersen, Cheryl

    2008-01-01

    This study examined relationships between financial indicators for nurse staffing and organizational system integration and change indicators. These indicators, along with hospital location and type, were examined in relation to the nursing financial indicators. Results showed that different indicators predicted each of the outcome variables. Nursing care hours were predicted by the hospital type, geographic location, and the system. Both nursing and patient care hours were significantly related to dissemination and benchmarking of clinical data.

  19. Language and motor abilities of preschool children who stutter: Evidence from behavioral and kinematic indices of nonword repetition performance

    PubMed Central

    Smith, Anne; Goffman, Lisa; Sasisekaran, Jayanthi; Weber-Fox, Christine

    2012-01-01

    Stuttering is a disorder of speech production that typically arises in the preschool years, and many accounts of its onset and development implicate language and motor processes as critical underlying factors. There have, however, been very few studies of speech motor control processes in preschool children who stutter. Hearing novel nonwords and reproducing them engages multiple neural networks, including those involved in phonological analysis and storage and speech motor programming and execution. We used this task to explore speech motor and language abilities of 31 children aged 4–5 years who were diagnosed as stuttering. We also used sensitive and specific standardized tests of speech and language abilities to determine which of the children who stutter had concomitant language and/or phonological disorders. Approximately half of our sample of stuttering children had language and/or phonological disorders. As previous investigations would suggest, the stuttering children with concomitant language or speech sound disorders produced significantly more errors on the nonword repetition task compared to typically developing children. In contrast, the children who were diagnosed as stuttering, but who had normal speech sound and language abilities, performed the nonword repetition task with equal accuracy compared to their normally fluent peers. Analyses of interarticulator motions during accurate and fluent productions of the nonwords revealed that the children who stutter (without concomitant disorders) showed higher variability in oral motor coordination indices. These results provide new evidence that preschool children diagnosed as stuttering lag their typically developing peers in maturation of speech motor control processes. Educational objectives The reader will be able to: (a) discuss why performance on nonword repetition tasks has been investigated in children who stutter; (b) discuss why children who stutter in the current study had a higher incidence

  20. Experimental study of the relative efficiency of nonlinear and restricted selection indices for ratios including quadratic and cubic terms.

    PubMed

    Campo, J L; Jorquera, M J

    1994-01-12

    mittels eines Selektionexperiments zugunsten des Quotienten Gewicht/(Länge)(n) verglichen. Das erste Experiment zielte auf Erhöhung von Gewicht der Puppe/(Länge der Puppe)(2) , während das zweite Experiment der Verbesserung von Gewicht der Larve/(Länge der Larve)(3) diente. Merkmale von Larve una Puppe wurden jeweils nach 14 und 21 Tagen gemessen in drei Wiederholungen und vier Selektionsgenerationen mit je 20% Selektion. Das Auswahlkriterium der Linien NL war (m(1) + Ĝ(1) )/(m(2) + Ĝ(2) )(n) , wobei m(1) und m(2) den Durchschnitt für Zähler- und Nennercharakteristika darstellen, Ĝ(1) und Ĝ(2) die angenommenen Werte sind und n 2 (Experiment 1) oder 3 (Experiment 2) ist. Der bei den Linien RI als Selektionskriterium verwendete Beschränkungsindex wurde zur Erhöhung des Zählers und zur Konstanthaltung des Nenners angenommen. Die Ergebnisse für den Quotienten waren bei beiden Experimenten zwischen Linien (P < .05) signifikant unterschiedlich, wobei die Reaktion der NL-Linien größer war. Beim Experiment 1 war die Reaktion der Linie NL im Zähler signifikant, während sie bei der Linie RI für beide Charakteristika positiv und signifikant war, die Linien waren signifikant verschieden hinsichtlich Länge der Puppe (P < .01). Das beim Experiment 2 erzielte Ergebnis für den Quotienten ergab sich aufgrund der Abnahme der beiden charakteristischen Komponenten. Die Ergebnisse dieser Experimente zeigten, daß die nicht-linearen Indexe die Quotienten erhöhten, welche im Nenner quadratische oder kubische Termini beinhalteten. Die linearen Indexe mit Restriktion für den Nenner des Quotienten stellten eine weniger wirksame Alternative dar. RESUMEN: Estudio experimental de la eficiencia relativa de indices de selección no lineales y con restricción para cocientes que incluyen cuadrados y cubos Un índice no lineal de selección (NL) fue comparado con un índice lineal con restricción (RI) en Tribolium, usando dos experimentos de selección a favor del cociente peso

  1. Evidence of alkali rich melt reactions with mantle peridotite : Natural observations and experimental analogues

    NASA Astrophysics Data System (ADS)

    Grant, T. B.; Milke, R.; Wunder, B.

    2012-04-01

    The Heldburg Phonolite, (Thuringia, Germany) is peculiar in its nature due to its absence of a Eu anomaly, and hence lack of feldspar fractionation, as well as the presence of spinel lherzolite xenocrysts. These observations suggest a higher than normal (mantle) pressure of origin, and its potential as a metasomatic agent at depth is explored in this work. Disequilibrium between the phonolite and its entrained upper mantle xenocrysts resulted in the development of secondary reaction rim assemblages of; (1) phlogopite + minor diopside around olivine, (2) pargasitic amphibole, phlogopite and minor diopside around orthopyroxene. We document both the natural rims and the attempts to reproduce them under experimental conditions, in order to elucidate the likely origin of the phonolite and its efficacy for metasomatising the upper mantle. Platinum capsules were loaded with mixtures of crushed mineral separates, (of pure synthetic forsterite, San Carlos olivine, synthetic enstatite or a natural enstatite from Kilosa, Tanzania) with a synthetic Fe-free phonolite melt in a 16:84% weight ratio, respectively. Experiments were run in a piston cylinder apparatus with CaF2 as the pressure medium. In addition to varying PT conditions, a wide range of water contents were tested (0-14wt%). It was found that pressures of 10-14 kbar, and temperatures of 900-1000°C, satisfy the conditions at which the reactions can form, thus, it is likely that the phonolite existed at upper mantle conditions. Water must be present to stabilize the desired hydrous phases, with >6wt% required at 900°C and 10 kbar. The destabilization of feldspar is also essential to the process, hence higher water contents are needed at the lowest PT conditions compared to 4-5 wt. % H2O at greater PT. The formation of amphibole around enstatite appears to be affected by sluggish reaction kinetics and the orientation of the host pyroxene, sometimes leading to diopside single rims. Furthermore we note some of the

  2. Experimental evidence on RH-dependent crossover from an electronic to protonic conduction with an oscillatory behaviour

    NASA Astrophysics Data System (ADS)

    Solanki, Vanaraj; Krupanidhi, S. B.; Nanda, K. K.

    2017-06-01

    An oxide semiconductor changes its resistance with exposure of water molecules and is accepted to be governed by electronic and protonic conduction in low and high humid atmosphere, respectively, without any experimental evidences. Here, we report on the experimental evidence of a relative humidity (RH) dependent crossover, from an electronic to protonic conduction and its oscillatory behaviour in mesoporous SnO2. Interestingly, oscillatory conduction observed in the intermediate humidity range (70%-90% RH) lies in between two monotonic variations that substantiate the competitive adsorption and desorption processes of oxygen species and water molecules. In addition, we have shown that the conduction process can be tuned predominantly electronic or protonic by pre- and post-UV treatment. The conductance increases by 2-3 orders as the conduction changes from pure electronic to protonic, suggesting an insulator-to-metal like transition.

  3. Counter-intuitive experimental evidence on the initiation of radical crack in ceramic thin films at the atomic scale

    NASA Astrophysics Data System (ADS)

    Zhuang, Chunqiang; Li, Zhipeng; Lin, Songsheng

    2015-10-01

    The basic issue related to radial crack in ceramic thin films has received considerable attention due to the fact that the radial crack plays an important role in evaluating the toughness properties of ceramic materials. In this work, an atomic-scale new experimental evidence is clearly presented to reveal the counter-intuitive initiation, the nucleation and the propagation mechanism of the radial crack in Al-Cr-N ceramic thin films.

  4. Counter-intuitive experimental evidence on the initiation of radical crack in ceramic thin films at the atomic scale

    SciTech Connect

    Zhuang, Chunqiang Li, Zhipeng; Lin, Songsheng

    2015-10-15

    The basic issue related to radial crack in ceramic thin films has received considerable attention due to the fact that the radial crack plays an important role in evaluating the toughness properties of ceramic materials. In this work, an atomic-scale new experimental evidence is clearly presented to reveal the counter-intuitive initiation, the nucleation and the propagation mechanism of the radial crack in Al-Cr-N ceramic thin films.

  5. Experimental evidences for a new model in the description of the adsorption-coupled reduction of Cr(VI) by protonated banana skin.

    PubMed

    López-García, Marta; Lodeiro, Pablo; Herrero, Roberto; Barriada, José L; Rey-Castro, Carlos; David, Calin; Sastre de Vicente, Manuel E

    2013-07-01

    This work reports experimental evidences, not previously considered, to evaluate the Cr(VI) removal by protonated banana skin biomass. Variations in the number of hydroxyl groups, quantified by potentiometric titrations, and CO2 evolution during experiments, were attributed mainly to the oxidation of hydroxylic entities present in the studied material. The results indicate that these groups together with the carboxylic moieties are the main functionalities involved on the adsorption-coupled reduction process. The column experiment carried out provides a new approach to obtain the maximum reduction capacity of the material (3.72 mmol g(-1)). Moreover, we hereby propose a model that reports the first evidence for the instant bound of Cr(III) species to the material used, formed after the reduction of Cr(VI) present in solution. The removal process was quantified carrying out experiments under various pHs, biomass doses and Cr(VI) concentrations, and the mechanism underlying chromium removal was identified.

  6. Scientific reasoning in early and middle childhood: the development of domain-general evidence evaluation, experimentation, and hypothesis generation skills.

    PubMed

    Piekny, Jeanette; Maehler, Claudia

    2013-06-01

    According to Klahr's (2000, 2005; Klahr & Dunbar, 1988) Scientific Discovery as Dual Search model, inquiry processes require three cognitive components: hypothesis generation, experimentation, and evidence evaluation. The aim of the present study was to investigate (a) when the ability to evaluate perfect covariation, imperfect covariation, and non-covariation evidence emerges, (b) when experimentation emerges, (c) when hypothesis generation skills emerge, and (d), whether these abilities develop synchronously during childhood. We administered three scientific reasoning tasks referring to the three components to 223 children of five age groups (from age 4.0 to 13.5 years). Our results show that the three cognitive components of domain-general scientific reasoning emerge asynchronously. The development of domain-general scientific reasoning begins with the ability to handle unambiguous data, progresses to the interpretation of ambiguous data, and leads to a flexible adaptation of hypotheses according to the sufficiency of evidence. When children understand the relation between the level of ambiguity of evidence and the level of confidence in hypotheses, the ability to differentiate conclusive from inconclusive experiments accompanies this development. Implications of these results for designing science education concepts for young children are briefly discussed.

  7. Experimental Evidence for a Structural-Dynamical Transition in Trajectory Space

    NASA Astrophysics Data System (ADS)

    Pinchaipat, Rattachai; Campo, Matteo; Turci, Francesco; Hallett, James E.; Speck, Thomas; Royall, C. Patrick

    2017-07-01

    Among the key insights into the glass transition has been the identification of a nonequilibrium phase transition in trajectory space which reveals phase coexistence between the normal supercooled liquid (active phase) and a glassy state (inactive phase). Here, we present evidence that such a transition occurs in experiments. In colloidal hard spheres, we find a non-Gaussian distribution of trajectories leaning towards those rich in locally favored structures (LFSs), associated with the emergence of slow dynamics. This we interpret as evidence for a nonequilibrium transition to an inactive LFS-rich phase. Reweighting trajectories reveals a first-order phase transition in trajectory space between a normal liquid and a LFS-rich phase. We also find evidence for a purely dynamical transition in trajectory space.

  8. The price elasticity of demand for heroin: Matched longitudinal and experimental evidence.

    PubMed

    Olmstead, Todd A; Alessi, Sheila M; Kline, Brendan; Pacula, Rosalie Liccardo; Petry, Nancy M

    2015-05-01

    This paper reports estimates of the price elasticity of demand for heroin based on a newly constructed dataset. The dataset has two matched components concerning the same sample of regular heroin users: longitudinal information about real-world heroin demand (actual price and actual quantity at daily intervals for each heroin user in the sample) and experimental information about laboratory heroin demand (elicited by presenting the same heroin users with scenarios in a laboratory setting). Two empirical strategies are used to estimate the price elasticity of demand for heroin. The first strategy exploits the idiosyncratic variation in the price experienced by a heroin user over time that occurs in markets for illegal drugs. The second strategy exploits the experimentally induced variation in price experienced by a heroin user across experimental scenarios. Both empirical strategies result in the estimate that the conditional price elasticity of demand for heroin is approximately -0.80.

  9. The price elasticity of demand for heroin: matched longitudinal and experimental evidence#

    PubMed Central

    Olmstead, Todd A.; Alessi, Sheila M.; Kline, Brendan; Pacula, Rosalie Liccardo; Petry, Nancy M.

    2015-01-01

    This paper reports estimates of the price elasticity of demand for heroin based on a newly constructed dataset. The dataset has two matched components concerning the same sample of regular heroin users: longitudinal information about real-world heroin demand (actual price and actual quantity at daily intervals for each heroin user in the sample) and experimental information about laboratory heroin demand (elicited by presenting the same heroin users with scenarios in a laboratory setting). Two empirical strategies are used to estimate the price elasticity of demand for heroin. The first strategy exploits the idiosyncratic variation in the price experienced by a heroin user over time that occurs in markets for illegal drugs. The second strategy exploits the experimentally-induced variation in price experienced by a heroin user across experimental scenarios. Both empirical strategies result in the estimate that the conditional price elasticity of demand for heroin is approximately −0.80. PMID:25702687

  10. Genetic susceptibility to retinopathy of prematurity: the evidence from clinical and experimental animal studies.

    PubMed

    Holmström, Gerd; van Wijngaarden, Peter; Coster, Douglas J; Williams, Keryn A

    2007-12-01

    Despite advances in management and treatment, retinopathy of prematurity remains a major cause of childhood blindness. Evidence for a genetic basis for susceptibility to retinopathy of prematurity is examined, including the influences of sex, ethnicity, and ocular pigmentation. The role of polymorphisms is explored in the genes for vascular endothelial growth factor and insulin-like growth factor-1, and of mutations in the Norrie disease gene. Insights into the genetic basis of retinopathy of prematurity provided by the animal model of oxygen induced retinopathy are examined. Evidence for a genetic component for susceptibility to retinopathy of prematurity is strong, although the molecular identity of the gene or genes involved remains uncertain.

  11. Observational Versus Experimental Studies: What’s the Evidence for a Hierarchy?

    PubMed Central

    Concato, John

    2004-01-01

    Summary: The tenets of evidence-based medicine include an emphasis on hierarchies of research design (i.e., study architecture). Often, a single randomized, controlled trial is considered to provide “truth,” whereas results from any observational study are viewed with suspicion. This paper describes information that contradicts and discourages such a rigid approach to evaluating the quality of research design. Unless a more balanced strategy evolves, new claims of methodological authority may be just as problematic as the traditional claims of medical authority that have been criticized by proponents of evidence-based medicine. PMID:15717036

  12. New approach for the determination of aerosol refractive indices - Part II: Experimental set-up and application to amorphous silica particles

    NASA Astrophysics Data System (ADS)

    Hubert, P.; Herbin, H.; Visez, N.; Pujol, O.; Petitprez, D.

    2017-10-01

    This article is the Part II of a work aimed at proposing a new method for determining the optical constants of aerosols. The Part I detailed the theoretical and numerical basis of an algorithm devoted to retrieve the imaginary and the real part of complex refractive indices from extinction spectra of aerosols. This algorithm associates the Mie theory, the single subtractive Kramers-Kronig relation, and an optimal estimation method in an iterative process. This Part II presents the experimental set-up developed to record simultaneously high spectral resolution extinction spectra and size distributions of airborne silica particles. Extinction spectra are measured with a high spectral resolution on a broad spectral range, including both infrared (650 - 2 , 500cm-1) and UV-visible (9 , 000 - 32 , 500cm-1) spectral regions. Experimental data were used to retrieve the complex refractive indices of aerosol particles. By associating the numerical procedure presented in the first paper and this experimental set-up, complex refractive indices of silica spherical aerosol particles have been determined under controlled experimental conditions. Additional comparison between experimental and simulated extinction spectra from retrieved complex refractive indices shows that this new methodology provides optical properties representative of the material.

  13. Experimental evidence of the rear capture of aerosol particles by raindrops

    NASA Astrophysics Data System (ADS)

    Lemaitre, Pascal; Querel, Arnaud; Monier, Marie; Menard, Thibault; Porcheron, Emmanuel; Flossmann, Andrea I.

    2017-03-01

    This article presents new measurements of the efficiency with which aerosol particles of accumulation mode size are collected by a 1.25 mm sized raindrop. These laboratory measurements provide the link to reconcile the scavenging coefficients obtained from theoretical approaches with those from experimental studies. We provide here experimental proof of the rear capture mechanism in the flow around drops, which has a fundamental effect on submicroscopic particles. These experiments thus confirm the efficiencies theoretically simulated by Beard (1974). Finally, we propose a semi-analytical expression to take into account this essential mechanism to calculate the collection efficiency for drops within the rain size range.

  14. Income Mobility Breeds Tolerance for Income Inequality: Cross-National and Experimental Evidence.

    PubMed

    Shariff, Azim F; Wiwad, Dylan; Aknin, Lara B

    2016-05-01

    American politicians often justify income inequality by referencing the opportunities people have to move between economic stations. Though past research has shown associations between income mobility and resistance to wealth redistribution policies, no experimental work has tested whether perceptions of mobility influence tolerance for inequality. In this article, we present a cross-national comparison showing that income mobility is associated with tolerance for inequality and experimental work demonstrating that perceptions of higher mobility directly affect attitudes toward inequality. We find support for both the prospect of upward mobility and the view that peoples' economic station is the product of their own efforts, as mediating mechanisms. © The Author(s) 2016.

  15. Experimental evidence of skyrmion-like configurations in bilayer nanodisks with perpendicular magnetic anisotropy

    SciTech Connect

    Stebliy, Maxim E. Kolesnikov, Alexander G.; Davydenko, Alexander V.; Ognev, Alexey V.; Samardak, Alexander S.; Chebotkevich, Ludmila A.

    2015-05-07

    Formation and existence of magnetic skyrmion-like configurations in bilayer nanodisks (Ta(3 nm)/[Co(0.37 nm)/Ni(0.58 nm)]{sub 10}){sub 2} with perpendicular magnetic anisotropy are shown experimentally at room temperature. Magnetization reversal through the skyrmion state is studied using magnetic hysteresis measurements. An evolution of skyrmion configurations in the nanodisk structure is analyzed. Experimental methods and micromagnetic simulations help to understand the magnetization reversal processes occurring through the stable skyrmion-like configurations. Formation of the intermediate C-states during magnetization reversal is demonstrated. The skyrmion number for all possible spin configurations is calculated.

  16. Psychoneuroimmunology: an interpretation of experimental and case study evidence towards a paradigm for predictable results.

    PubMed

    Kalt, H W

    2000-07-01

    This paper surveys a number of key experiments and case studies relating to psychoneuroimmunology. It finds that most techniques to influence or even direct the immune system via the mind fall into a series of theoretical categories called passive, active and targeted effects. By examining the results of experiments and studies in the light of these categories a number of important conclusions are drawn. These conclusions explain differences in experimental results, describe those variables that appear to be central to obtaining results, and describe in detail where experimentation should be concentrated to further knowledge of psychoneuroimmunology.

  17. Summer Nights: A Review of the Evidence of Seasonal Variations in Sexual Health Indicators among Young People

    ERIC Educational Resources Information Center

    Macdowall, Wendy; Wellings, Kaye; Stephenson, Judith; Glasier, Anna

    2008-01-01

    Purpose: This paper aims to examine whether greater consideration should be given to the timing of sexual health interventions within the calendar year. Design/methodology/approach: The paper uses a review of the literature. Findings: The evidence points to seasonality in a number of areas of sexual health among young people, including: the timing…

  18. Summer Nights: A Review of the Evidence of Seasonal Variations in Sexual Health Indicators among Young People

    ERIC Educational Resources Information Center

    Macdowall, Wendy; Wellings, Kaye; Stephenson, Judith; Glasier, Anna

    2008-01-01

    Purpose: This paper aims to examine whether greater consideration should be given to the timing of sexual health interventions within the calendar year. Design/methodology/approach: The paper uses a review of the literature. Findings: The evidence points to seasonality in a number of areas of sexual health among young people, including: the timing…

  19. Curriculum-Based Measurement Oral Reading as an Indicator of Reading Achievement: A Meta-Analysis of the Correlational Evidence

    ERIC Educational Resources Information Center

    Reschly, Amy L.; Busch, Todd W.; Betts, Joseph; Deno, Stanley L.; Long, Jeffrey D.

    2009-01-01

    This meta-analysis summarized the correlational evidence of the association between the CBM Oral Reading measure (R-CBM) and other standardized measures of reading achievement for students in grades 1-6. Potential moderating variables were also examined (source of criterion test, administration format, grade level, length of time, and type of…

  20. What Makes an Effective Teacher? Quasi-Experimental Evidence. NBER Working Paper No. 16885

    ERIC Educational Resources Information Center

    Lavy, Victor

    2011-01-01

    This paper measures empirically the relationship between classroom teaching practices and student achievements. Based on primary- and middle-school data from Israel, I find very strong evidence that two important elements of teaching practices cause student achievements to improve. In particular, classroom teaching that emphasizes the instilment…

  1. Long-Term Effects of Teacher Performance Pay: Experimental Evidence from India

    ERIC Educational Resources Information Center

    Muralidharan, Karthik

    2012-01-01

    While the idea of teacher performance-pay is increasingly making its way into policy, the evidence on the effectiveness of such programs is both limited and mixed. The central questions in the literature on teacher performance pay to date have been whether teacher performance pay based on test scores can improve student achievement, and whether…

  2. Evidence for Tempo-Specific Timing in Music Using a Web-Based Experimental Setup

    ERIC Educational Resources Information Center

    Honing, Henkjan

    2006-01-01

    Perceptual invariance has been studied and found in several domains of cognition, including those of speech, motor behavior, and object motion. It has also been the topic of several studies in music perception. However, the existing perceptual studies present rather inconclusive evidence with regard to the perceptual invariance of expressive…

  3. Teacher Performance Pay: Experimental Evidence from India. NBER Working Paper No. 15323

    ERIC Educational Resources Information Center

    Muralidharan, Karthik; Sundararaman, Venkatesh

    2009-01-01

    Performance pay for teachers is frequently suggested as a way of improving education outcomes in schools, but the theoretical predictions regarding its effectiveness are ambiguous and the empirical evidence to date is limited and mixed. We present results from a randomized evaluation of a teacher incentive program implemented across a large…

  4. Teacher Incentives in Developing Countries: Experimental Evidence from India. Working Paper 2008-13

    ERIC Educational Resources Information Center

    Muralidharan, Karthik; Sundararaman, Venkatesh

    2008-01-01

    Performance pay for teachers is frequently suggested as a way of improving educational outcomes in schools, but the empirical evidence to date on its effectiveness is limited and mixed. We present results from a randomized evaluation of a teacher incentive program implemented across a representative sample of government-run rural primary schools…

  5. Persistence of Learning Gains from Computer Assisted Learning: Experimental Evidence from China

    ERIC Educational Resources Information Center

    Mo, D.; Zhang, L.; Wang, J.; Huang, W.; Shi, Y.; Boswell, M.; Rozelle, S.

    2015-01-01

    Computer assisted learning (CAL) programs have been shown to be effective in improving educational outcomes. However, the existing studies on CAL have almost all been conducted over a short period of time. There is very little evidence on how the impact evolves over time. In response, we conducted a clustered randomized experiment involving 2741…

  6. Evidence for Tempo-Specific Timing in Music Using a Web-Based Experimental Setup

    ERIC Educational Resources Information Center

    Honing, Henkjan

    2006-01-01

    Perceptual invariance has been studied and found in several domains of cognition, including those of speech, motor behavior, and object motion. It has also been the topic of several studies in music perception. However, the existing perceptual studies present rather inconclusive evidence with regard to the perceptual invariance of expressive…

  7. What Makes an Effective Teacher? Quasi-Experimental Evidence. NBER Working Paper No. 16885

    ERIC Educational Resources Information Center

    Lavy, Victor

    2011-01-01

    This paper measures empirically the relationship between classroom teaching practices and student achievements. Based on primary- and middle-school data from Israel, I find very strong evidence that two important elements of teaching practices cause student achievements to improve. In particular, classroom teaching that emphasizes the instilment…

  8. Evidence That Counts: 12 Teacher-Led Randomised Controlled Trials and Other Styles of Experimental Research

    ERIC Educational Resources Information Center

    Churches, Richard; McAleavy, Tony

    2016-01-01

    This publication contains 12 (A3 open-out) poster-style reports of teacher experimental research. The style of presentation parallels the type of preliminary reporting common at academic conferences and postgraduate events. At the same time, it aims to act as a form of short primer to introduce teachers to the basic options that there are when…

  9. The Effects of Television Advertising on Children. Report No. 2: Second Year Experimental Evidence. Final Report.

    ERIC Educational Resources Information Center

    Atkin, Charles K.

    This report, the second in a series of six reports on television advertising and children, presents the results from a series of experimental studies designed to test children's intentional and incidental learning from television commercials. A total of 400 elementary school students of varying socioeconomic status participated in the study, with…

  10. Experimental evidence of nitrous acid formation in the electron beam treatment of flue gas

    NASA Astrophysics Data System (ADS)

    Mätzing, H.; Namba, H.; Tokunaga, O.

    1994-03-01

    In the Electron Beam Dry Scrubbing (EBDS) process, flue gas from fossil fuel burning power plants is irradiated with accelerated (300-800 keV) electrons. Thereby, nitrogen oxide (NO x) and sulfur dioxide (SO 2) traces are transformed into nitric and sulfuric acids, respectively, which are converted into particulate ammonium nitrate and sulfate upon the addition of ammonia. The powdery can be filtered from the main gas stream and can be sold as agricultural fertilizer. A lot of experimental investigations have been performed on the EBDS process and computer models have been developed to interpret the experimental results and to predict economic improvements. According to the model calculations, substantial amounts of intermediate nitrous acid (HNO 2) are formed in the electron beam treatment of flue gas. However, no corresponding experimental information is available so far. Therefore, we have undertaken the first experimental investigation about the formation of nitrous acid in an irradiated mixture of NO in synthetic air. Under these conditions, aerosol formation is avoided. UV spectra of the irradiated gas were recorded in the wavelength range λ = 345-375 nm. Both NO 2 and HNO 2 have characteristic absorption bands in this wavelength range. Calibration spectra of NO 2 were subtracted from the sample spectra. The remaining absorption bands can clearly be assigned to nitrous acid. The concentration of nitrous acid was determined by differential optical absorption. It was found lower than the model prediction. The importance of nitrous acid formation in the EBDS process needs to be clarified.

  11. Mimicking Aphasic Semantic Errors in Normal Speech Production: Evidence from a Novel Experimental Paradigm

    ERIC Educational Resources Information Center

    Hodgson, Catherine; Lambon Ralph, Matthew A.

    2008-01-01

    Semantic errors are commonly found in semantic dementia (SD) and some forms of stroke aphasia and provide insights into semantic processing and speech production. Low error rates are found in standard picture naming tasks in normal controls. In order to increase error rates and thus provide an experimental model of aphasic performance, this study…

  12. Experimental evidence of a symbiosis between red-cockaded woodpeckers and fungi

    Treesearch

    Michelle A. Jusino; Daniel L. Lindner; Mark T. Banik; Kevin R. Rose; Jeffrey R. Walters

    2016-01-01

    Primary cavity excavators, such as woodpeckers, are ecosystem engineers in many systems. Associations between cavity excavators and fungi have long been hypothesized to facilitate cavity excavation, but these relationships have not been experimentally verified. Fungi may help excavators by softening wood, while excavators may facilitate fungal dispersal. Here we...

  13. Supplying Disadvantaged Schools with Effective Teachers: Experimental Evidence on Secondary Math Teachers from Teach For America

    ERIC Educational Resources Information Center

    Chiang, Hanley S.; Clark, Melissa A.; McConnell, Sheena

    2017-01-01

    Teach For America (TFA) is an important but controversial source of teachers for hard-to-staff subjects in high-poverty U.S. schools. We present findings from the first large-scale experimental study of secondary math teachers from TFA. We find that TFA teachers are more effective than other math teachers in the same schools, increasing student…

  14. Supplying Disadvantaged Schools with Effective Teachers: Experimental Evidence on Secondary Math Teachers from Teach For America

    ERIC Educational Resources Information Center

    Chiang, Hanley S.; Clark, Melissa A.; McConnell, Sheena

    2017-01-01

    Teach For America (TFA) is an important but controversial source of teachers for hard-to-staff subjects in high-poverty U.S. schools. We present findings from the first large-scale experimental study of secondary math teachers from TFA. We find that TFA teachers are more effective than other math teachers in the same schools, increasing student…

  15. Mimicking Aphasic Semantic Errors in Normal Speech Production: Evidence from a Novel Experimental Paradigm

    ERIC Educational Resources Information Center

    Hodgson, Catherine; Lambon Ralph, Matthew A.

    2008-01-01

    Semantic errors are commonly found in semantic dementia (SD) and some forms of stroke aphasia and provide insights into semantic processing and speech production. Low error rates are found in standard picture naming tasks in normal controls. In order to increase error rates and thus provide an experimental model of aphasic performance, this study…

  16. Experimental Evaluations of Elementary Science Programs: A Best-Evidence Synthesis

    ERIC Educational Resources Information Center

    Slavin, Robert E.; Lake, Cynthia; Hanley, Pam; Thurston, Allen

    2014-01-01

    This article presents a systematic review of research on the achievement outcomes of all types of approaches to teaching science in elementary schools. Study inclusion criteria included use of randomized or matched control groups, a study duration of at least 4 weeks, and use of achievement measures independent of the experimental treatment. A…

  17. Deciphering The Speed of Link: Experimental Evidence of a Rapid Increase in Soil Respiration Following the Onset of Photosynthesis

    NASA Astrophysics Data System (ADS)

    Kayler, Z. E.; Keitel, C.; Jansen, K.; Gessler, A.

    2011-12-01

    The degree of coupling between aboveground assimilation and transport with below-ground metabolism is an indicator of ecosystem nutrient cycling and energy turnover in the rhizosphere as well as having a large impact on their long-term storage capacity in the soil. Understanding how and when assimilates arrive below-ground for mineralization is necessary to predict how nutrient and energy cycles might be altered by current and future changes in climate, species distribution and land use. Currently, there are two proposed mechanisms that describe the link between assimilation and below-ground respiration via the phloem: 1) the transport of assimilates basipetally according to the Münch theory, and 2) pressure-concentration waves. The transport of assimilates through the phloem by mechanism 1 is often quantified through isotopic labeling studies. Thus, the time between isotopic labeling in the canopy and when the labeled carbon is respired from the rhizoshpere characterizes the degree of coupling between aboveground and below-ground metabolism. The timing between the uptake and below-ground respiration of the labeled carbon is termed the "speed of link". Based on statistical approaches, recent studies have reported a speed of link on the order of one day or less in mature forests, which is too fast for phloem transport by molecular diffusion or classical sink-source dynamics. These studies often cite mechanism 2 to support their conclusions despite the lack of experimental evidence. In this presentation, we report results from experiments designed to observe the mechanisms behind the speed of link of Douglas-fir saplings. We kept the plants for several days (0,1 and 6 days) in the dark to create a large carbon source-sink gradient with the intention of inducing a strong pressure-concentration wave. Following the no light treatment, in a controlled growth chamber, we introduced labelled CO2 prior to exposing the plant to light. Upon exposing the plants to light, the

  18. When and why do territorial coalitions occur? Experimental evidence from a fiddler crab.

    PubMed

    Detto, Tanya; Jennions, Michael D; Backwell, Patricia R Y

    2010-05-01

    Neighboring territory owners are often less aggressive toward each other than to strangers ("dear enemy" effect). There is, however, little evidence for territorial defense coalitions whereby a neighbor will temporarily leave his/her own territory, enter that of a neighbor, and cooperate in repelling a conspecific intruder. This is surprising, as theoreticians have long posited the existence of such coalitions and the circumstances under which they should evolve. Here we document territorial defense coalitions in the African fiddler crab Uca annulipes, which lives in large colonies wherein each male defends a burrow and its surrounding area against neighbors and "floaters" (burrowless males). Fights between a resident and a floater sometimes involve another male who has left his territory to fight the floater challenging his neighbor. Using simple experiments, we provide the first evidence of the rules determining when territorial coalitions form. Our results support recent models that suggest that these coalitions arise from by-product mutualism.

  19. Exercise and Physical Activity in Mental Disorders: Clinical and Experimental Evidence

    PubMed Central

    Zschucke, Elisabeth; Gaudlitz, Katharina

    2013-01-01

    Several epidemiological studies have shown that exercise (EX) and physical activity (PA) can prevent or delay the onset of different mental disorders, and have therapeutic benefits when used as sole or adjunct treatment in mental disorders. This review summarizes studies that used EX interventions in patients with anxiety, affective, eating, and substance use disorders, as well as schizophrenia and dementia/mild cognitive impairment. Despite several decades of clinical evidence with EX interventions, controlled studies are sparse in most disorder groups. Preliminary evidence suggests that PA/EX can induce improvements in physical, subjective and disorder-specific clinical outcomes. Potential mechanisms of action are discussed, as well as implications for psychiatric research and practice. PMID:23412549

  20. Experimental evidence and the Landau-Zener promotion in nucleus-nucleus collisions

    SciTech Connect

    Cindro, N.; Freeman, R.M.; Haas, F.

    1986-04-01

    Recent data from C+O collisions are analyzed in terms of the Landau-Zener promotion in nuclei. Evidence for the presence of this mechanism in nuclear collisions is of considerable interest, since it provides a signature of single-particle orbitals in molecular-type potentials and, at the same time, paves the way to a microscopic understanding of the collision dynamics, in particular of the energy dissipation rate. The analyzed data are of two types: integrated cross sections and angular distributions of inelastically scattered particles. The first set of data shows structure qualitatively consistent with recent calculations of the Landau-Zener effect; for this set of data no other reasonable explanation is presently available. The second set of data, while consistent with the presence of the Landau-Zener promotion, is examined in terms of other possible explanations too. The combined data show evidence favoring the presence of the Landau-Zener promotion in nucleus-nucleus collisions.

  1. Experimental Evidence for Atmospheric Neutrino Oscillations: MACRO, Soudan 2, and the Future

    NASA Astrophysics Data System (ADS)

    Gallagher, Hugh

    2005-06-01

    In this note I will summarize the most recent results from the MACRO and Soudan 2 experiments. Despite their limited statistics compared with SuperKamiokande these experiments provide strong confirmatory evidence, with completely different systematics, of atmospheric neutrino oscillations. I will briefly mention the additional information that the current generation of running experiments may provide and the important role atmospheric neutrinos can continue to play in the exploration of the neutrino sector.

  2. Is hexachloro-cyclo-triphosphazene aromatic? Evidence from experimental charge density analysis.

    PubMed

    Jancik, Vojtech; Cortés-Guzmán, Fernando; Herbst-Irmer, Regine; Martínez-Otero, Diego

    2017-01-30

    Experimental charge density studies of hexachloro-cyclo-triphosphazene (1) and the boat conformation of octachloro-cyclo-tetraphosphazene (2a) were performed in order to unambiguously describe the origin of the electron delocalization in the P3N3 ring in 1. The obtained results were compared to DFT studies in solid state and the gas phase. Electron density analysis revealed a highly polarized nature of the P-N bonds and a modular structure of the P3N3 and P4N4 rings, which can be separated into independent Cl2PN units with a perfect transferability between the compounds. Further analysis of the source function experimentally proves the presence of negative hyperconjugation involving both out-of-plane and in-plane nitrogen electrons as well as electrons of the chlorine atoms. Finally, these results discard the presence of pseudoaromatic delocalization in the nearly-planar P3N3 ring.

  3. Experimental and theoretical evidence for bilayer-by-bilayer surface melting of crystalline ice.

    PubMed

    Sánchez, M Alejandra; Kling, Tanja; Ishiyama, Tatsuya; van Zadel, Marc-Jan; Bisson, Patrick J; Mezger, Markus; Jochum, Mara N; Cyran, Jenée D; Smit, Wilbert J; Bakker, Huib J; Shultz, Mary Jane; Morita, Akihiro; Donadio, Davide; Nagata, Yuki; Bonn, Mischa; Backus, Ellen H G

    2017-01-10

    On the surface of water ice, a quasi-liquid layer (QLL) has been extensively reported at temperatures below its bulk melting point at 273 K. Approaching the bulk melting temperature from below, the thickness of the QLL is known to increase. To elucidate the precise temperature variation of the QLL, and its nature, we investigate the surface melting of hexagonal ice by combining noncontact, surface-specific vibrational sum frequency generation (SFG) spectroscopy and spectra calculated from molecular dynamics simulations. Using SFG, we probe the outermost water layers of distinct single crystalline ice faces at different temperatures. For the basal face, a stepwise, sudden weakening of the hydrogen-bonded structure of the outermost water layers occurs at 257 K. The spectral calculations from the molecular dynamics simulations reproduce the experimental findings; this allows us to interpret our experimental findings in terms of a stepwise change from one to two molten bilayers at the transition temperature.

  4. Experimental and theoretical evidence for bilayer-by-bilayer surface melting of crystalline ice

    PubMed Central

    Sánchez, M. Alejandra; Kling, Tanja; Ishiyama, Tatsuya; van Zadel, Marc-Jan; Mezger, Markus; Jochum, Mara N.; Cyran, Jenée D.; Smit, Wilbert J.; Bakker, Huib J.; Shultz, Mary Jane; Morita, Akihiro; Donadio, Davide; Nagata, Yuki; Bonn, Mischa; Backus, Ellen H. G.

    2017-01-01

    On the surface of water ice, a quasi-liquid layer (QLL) has been extensively reported at temperatures below its bulk melting point at 273 K. Approaching the bulk melting temperature from below, the thickness of the QLL is known to increase. To elucidate the precise temperature variation of the QLL, and its nature, we investigate the surface melting of hexagonal ice by combining noncontact, surface-specific vibrational sum frequency generation (SFG) spectroscopy and spectra calculated from molecular dynamics simulations. Using SFG, we probe the outermost water layers of distinct single crystalline ice faces at different temperatures. For the basal face, a stepwise, sudden weakening of the hydrogen-bonded structure of the outermost water layers occurs at 257 K. The spectral calculations from the molecular dynamics simulations reproduce the experimental findings; this allows us to interpret our experimental findings in terms of a stepwise change from one to two molten bilayers at the transition temperature. PMID:27956637

  5. Experimental Evidence of Weak Excluded Volume Effects for Nanochannel Confined DNA

    NASA Astrophysics Data System (ADS)

    Gupta, Damini; Miller, Jeremy J.; Muralidhar, Abhiram; Mahshid, Sara; Reisner, Walter; Dorfman, Kevin D.

    In the classical de Gennes picture of weak polymer nanochannel confinement, the polymer contour is envisioned as divided into a series of isometric blobs. Strong excluded volume interactions are present both within a blob and between blobs. In contrast, for semiflexible polymers like DNA, excluded volume interactions are of borderline strength within a blob but appreciable between blobs, giving rise to a chain description consisting of a string of anisometric blobs. We present experimental validation of this subtle effect of excluded volume for DNA nanochannel confinement by performing measurements of variance in chain extension of T4 DNA molecules as a function of effective nanochannel size (305-453 nm). Additionally, we show an approach to systematically reduce the effect of molecular weight dispersity of DNA samples, a typical experimental artifact, by combining confinement spectroscopy with simulations.

  6. Experimental evidence and early translational steps using bone marrow derived stem cells after human stroke.

    PubMed

    Kasahara, Yukiko; Ihara, Masafumi; Taguchi, Akihiko

    2013-01-01

    Neurogenesis is principally restricted to the subventricular zone of the lateral ventricle wall and the subgranular zone of the hippocampal dentate gyrus in physiological situations. However, neuronal stem cells are known to be mobilized into the post- and peristroke area and we have demonstrated that appropriate support of these stem cells, achieved by therapeutic angiogenesis, enhances neuroregeneration followed by neuronal functional recovery in an experimental stroke model. We also found that neural stem cells are mobilized in patients after stroke, as well as in animal models. Based on these observations, we have started cell-based therapy using autologous bone marrow-derived stem/progenitor cells in patients after stroke. This review summarizes the findings of recent experimental and clinical studies that have focused on neurogenesis in the injured brain after cerebral infarction. We also refer to the challenges for future cell-based therapy, including regeneration of the aged brain. Copyright © 2013 S. Karger AG, Basel.

  7. Experimental evidence of Willis coupling in a one-dimensional effective material element

    NASA Astrophysics Data System (ADS)

    Muhlestein, Michael B.; Sieck, Caleb F.; Wilson, Preston S.; Haberman, Michael R.

    2017-06-01

    The primary objective of acoustic metamaterial research is to design subwavelength systems that behave as effective materials with novel acoustical properties. One such property couples the stress-strain and the momentum-velocity relations. This response is analogous to bianisotropy in electromagnetism, is absent from common materials, and is often referred to as Willis coupling after J.R., Willis, who first described it in the context of the dynamic response of heterogeneous elastic media. This work presents two principal results: first, experimental and theoretical demonstrations, illustrating that Willis properties are required to obtain physically meaningful effective material properties resulting solely from local behaviour of an asymmetric one-dimensional isolated element and, second, an experimental procedure to extract the effective material properties from a one-dimensional isolated element. The measured material properties are in very good agreement with theoretical predictions and thus provide improved understanding of the physical mechanisms leading to Willis coupling in acoustic metamaterials.

  8. Experimental evidence of asymmetrical competition between two species of parasitic copepods.

    PubMed Central

    Dawson, L H; Renaud, F; Guégan, J F; de Meeûs, T

    2000-01-01

    Lepeophtheirus thompsoni and Lepeophtheirus europaensis are two parasitic copepods naturally isolated on their sympatric hosts, i.e. turbot (Psetta maxima L.) and brill (Scophthalmus rhombus L.), respectively They are able to meet, mate and hybridize on turbot experimentally but they are naturally prevented from doing so by a strong host preference when given a choice. Theory suggests that such a pattern is possible, but only under conditions of competition for the resource. In the present study the attachment rates of the two copepods were studied experimentally under various conditions of competition, infectious dose and number of available hosts. The results suggest a greater sensitivity to competition for the generalist species L. europaensis than for the specialist L. thompsoni, which is in agreement with theoretical predictions. PMID:11075710

  9. Theoretical and experimental evidence of non-symmetric doubly localized rogue waves.

    PubMed

    He, Jingsong; Guo, Lijuan; Zhang, Yongshuai; Chabchoub, Amin

    2014-11-08

    We present determinant expressions for vector rogue wave (RW) solutions of the Manakov system, a two-component coupled nonlinear Schrödinger (NLS) equation. As a special case, we generate a family of exact and non-symmetric RW solutions of the NLS equation up to third order, localized in both space and time. The derived non-symmetric doubly localized second-order solution is generated experimentally in a water wave flume for deep-water conditions. Experimental results, confirming the characteristic non-symmetric pattern of the solution, are in very good agreement with theory as well as with numerical simulations, based on the modified NLS equation, known to model accurately the dynamics of weakly nonlinear wave packets in deep water.

  10. Experimental Evidence of the 90° Stop Band in the GSI UNILAC

    NASA Astrophysics Data System (ADS)

    Groening, L.; Barth, W.; Bayer, W.; Clemente, G.; Dahl, L.; Forck, P.; Gerhard, P.; Hofmann, I.; Kaiser, M. S.; Maier, M.; Mickat, S.; Milosic, T.; Jeon, D.; Uriot, D.

    2009-06-01

    In a particle accelerator with a periodic structure beam space charge force may excite resonant beam emittance growth if the particle’s transverse phase advance approaches 90°. A recent simulation study with the PARMILA code [D. Jeon , Phys. Rev. ST Accel. BeamsPRABFM1098-4402 12, 054204 (2009)]10.1103/PhysRevSTAB.12.054204 has shown the feasibility of measuring the stop band of this fourth order resonance in the GSI Universal Linear Accelerator UNILAC and proposed its experimental verification, which is reported here. Measurements of transverse phase space distributions behind a periodically focusing structure reveal a fourfold symmetry characteristic of fourth order resonances as well as a resonance stop band above σ0=90° per focusing cell. These experimental findings agree with results from three different beam dynamics simulation codes, i.e., DYNAMION, PARMILA, and TRACEWIN.

  11. Theoretical and experimental evidence of non-symmetric doubly localized rogue waves

    PubMed Central

    He, Jingsong; Guo, Lijuan; Zhang, Yongshuai; Chabchoub, Amin

    2014-01-01

    We present determinant expressions for vector rogue wave (RW) solutions of the Manakov system, a two-component coupled nonlinear Schrödinger (NLS) equation. As a special case, we generate a family of exact and non-symmetric RW solutions of the NLS equation up to third order, localized in both space and time. The derived non-symmetric doubly localized second-order solution is generated experimentally in a water wave flume for deep-water conditions. Experimental results, confirming the characteristic non-symmetric pattern of the solution, are in very good agreement with theory as well as with numerical simulations, based on the modified NLS equation, known to model accurately the dynamics of weakly nonlinear wave packets in deep water. PMID:25383023

  12. Experimental evidence of Willis coupling in a one-dimensional effective material element.

    PubMed

    Muhlestein, Michael B; Sieck, Caleb F; Wilson, Preston S; Haberman, Michael R

    2017-06-13

    The primary objective of acoustic metamaterial research is to design subwavelength systems that behave as effective materials with novel acoustical properties. One such property couples the stress-strain and the momentum-velocity relations. This response is analogous to bianisotropy in electromagnetism, is absent from common materials, and is often referred to as Willis coupling after J.R., Willis, who first described it in the context of the dynamic response of heterogeneous elastic media. This work presents two principal results: first, experimental and theoretical demonstrations, illustrating that Willis properties are required to obtain physically meaningful effective material properties resulting solely from local behaviour of an asymmetric one-dimensional isolated element and, second, an experimental procedure to extract the effective material properties from a one-dimensional isolated element. The measured material properties are in very good agreement with theoretical predictions and thus provide improved understanding of the physical mechanisms leading to Willis coupling in acoustic metamaterials.

  13. Experimental evidence of E × B plasma rotation in a 2.45 GHz hydrogen discharge

    NASA Astrophysics Data System (ADS)

    Cortázar, O. D.; Megía-Macías, A.; Tarvainen, O.; Koivisto, H.

    2015-12-01

    An experimental observation of a rotating plasma structure in a 2.45 GHz microwave-driven hydrogen discharge is reported. The rotation is presumably produced by E × B drift. The formation of the rotating plasma structure is sensitive to the strength of the off-resonance static magnetic field. The rotation frequency is on the order of 10 kHz and is affected by the neutral gas pressure and applied microwave power.

  14. Experimental evidence of Xe incorporation in Schottky defects in UO{sub 2}

    SciTech Connect

    Bès, René; Martin, Philippe Vathonne, Emerson; Delorme, Rémy; Sabathier, Catherine; Freyss, Michel; Bertolus, Marjorie; Glatzel, Pieter

    2015-03-16

    We report here the direct experimental observation of the preferential xenon incorporation site in uranium dioxide and analyse how its incorporation evolves with the annealing temperature. We show that High Energy Resolution Fluorescence Detection X-ray Absorption Near Edge Structure in combination with first-principles calculations enable a precise determination of the Xe incorporation site. Our finding provides important insight for the understanding and modeling of noble gases behavior in nuclear oxide fuel.

  15. Recent experimental evidence for the Los Alamos proton storage ring beam instability

    SciTech Connect

    Plum, M.A.; Fitzgerald, D.H.; Johnson, D.

    1997-09-01

    The peak intensity of the PSR is limited by a fast transverse instability. In 1996 the authors started a project to upgrade the PSR to 200 {mu}A at 30 Hz, which requires operation above the instability threshold achieved with the present rf system. The authors have, therefore, resumed their experimental program to understand and control the instability. In this paper they will present their latest data.

  16. Do Choice Experiments Generate Reliable Willingness to Pay Estimates Theory and Experimental Evidence

    DTIC Science & Technology

    2015-01-01

    predictions of voting theory combined with the theoretical model from Part II? A. Experiment 2 Design 15 Experiment 2 is designed to create a...the choice set design methodologies. The experiment took 40-45 minutes to complete, and average experimental earnings were in the range of $ 15 -$20.6...student take-home pay ranges from $65-$100. Thus, an additional $ 15 -$20 for 45 minutes to one hour of time represents a significant addition to a

  17. Natural and experimental evidence of viscerotropic infection caused by Leishmania tropica from North Sinai, Egypt.

    PubMed

    Doha, Said A; Shehata, Magdi G; Fahmy, Adel R; Samy, Abdallah M

    2014-08-01

    Cutaneous leishmaniasis (CL) is a neglected clinical form that is quite prevalent in Eastern North parts of the country in Sinai Peninsula. Leishmania tropica was identified by previous reports as the causative agent responsible for viscerotropic infections in-patients and experimental animals. Here, we reported the viscerotropic infections from naturally infected rodent Gerbillus pyramidum floweri collected from North-Sinai. Footpad and tail lesions, spleenomegaly, and malformed dark-colored spleen were the characteristic CL symptoms. The spleen of the rodent found positive to amastigote impression smear. ITS-1 DNA was sequenced and revealed 100% identity of the strain in the current study to the other L. tropica sequences identified from the patients with the suspected CL and inhabited the same study area. The current findings confirmed the susceptibility of gerbil to L. tropica, and raise the concerns for the role of rodents as accidental host suffering the infections. The susceptibility of wild and experimental rodents to the same L. tropica strain was also investigated; BALB/c and G. pyramidum were more susceptible to L. tropica (24.33 ± 4.37 and 25 ± 4.58 days post-infection, respectively). Similar viscerotropic pathologies were reported in experimental infection of only golden hamster (≈ 120 days post-infection), and G. p. floweri (≈ 160 days post-infection).

  18. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling.

    PubMed

    Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

    2017-01-28

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 10(3) to 10(4) s(-1) using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  19. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling

    NASA Astrophysics Data System (ADS)

    Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

    2017-01-01

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 103 to 104 s-1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  20. Examination of experimental evidence of chaos in the bound states of 208Pb

    NASA Astrophysics Data System (ADS)

    Muñoz, L.; Molina, R. A.; Gómez, J. M. G.; Heusler, A.

    2017-01-01

    We study the spectral fluctuations of the 208Pb nucleus using the complete experimental spectrum of 151 states up to excitation energies of 6.20 MeV recently identified at the Maier-Leibnitz Laboratorium at Garching, Germany. For natural parity states the results are very close to the predictions of random matrix theory (RMT) for the nearest-neighbor spacing distribution. A quantitative estimate of the agreement is given by the Brody parameter ω , which takes the value ω =0 for regular systems and ω ≃1 for chaotic systems. We obtain ω =0.85 which is, to our knowledge, the closest value to chaos ever observed in experimental bound states of nuclei. By contrast, the results for unnatural parity states are far from RMT behavior. We interpret these results as a consequence of the strength of the residual interaction in 208Pb, which, according to experimental data, is much stronger for natural than for unnatural parity states. In addition, our results show that chaotic and nonchaotic nuclear states coexist in the same energy region of the spectrum.

  1. Experimental evidence for strong stabilizing forces at high functional diversity of aquatic microbial communities.

    PubMed

    Carrara, Francesco; Giometto, Andrea; Seymour, Mathew; Rinaldo, Andrea; Altermatt, Florian

    2015-05-01

    Unveiling the mechanisms that promote coexistence in biological communities is a fundamental problem in ecology. Stable coexistence of many species is commonly observed in natural communities. Most of these natural communities, however, are composed of species from multiple trophic and functional groups, while theory and experiments on coexistence have been focusing on functionally similar species. Here, we investigated how functional diversity affects the stability of species coexistence and productivity in multispecies communities by characterizing experimentally all pairwise species interactions in a pool of 11 species of eukaryotes (10 protists and one rotifer) belonging to three different functional groups. Species within the same functional group showed stronger competitive interactions compared to among-functional group interactions. This often led to competitive exclusion between species that had higher functional relatedness, but only at low levels of species richness. Communities with higher functional diversity resulted in increased species coexistence and community biomass production. Our experimental findings and the results of a stochastic model tailored to the experimental interaction matrix suggest the emergence of strong stabilizing forces when species from different functional groups interact in a homogeneous environment. By combining theoretical analysis with experiments we could also disentangle the relationship between species richness and functional diversity, showing that functional diversity per se is a crucial driver of productivity and stability in multispecies community.

  2. An Innovative Assay for the Analysis of In Vitro Endothelial Remodeling: Experimental and Computational Evidence.

    PubMed

    Scianna, Marco; Bassino, Eleonora; Munaron, Luca

    2017-02-01

    The molecular and cellular mechanisms underlying vascular remodeling are currently investigated by experimental strategies which aim to mimic the complex environmental conditions found in vivo. Some of them focus on the tubulogenic activity of dispersed endothelial cell populations, while others evaluate vascular sprouting. Here we propose a new method to assess matrigel invasion starting from confluent or subconfluent monolayers of human microvascular ECs (HMVEC) seeded on different substrates. The experimental setting is also validated by an improved hybrid multiscale mathematical approach, which integrates a mesoscopic grid-based cellular Potts model, that describes HMVEC phenomenology, with a continuous one, accounting for the kinetics of diffusing growth factors. Both experimental and theoretical approaches show that the endothelial potential to invade, migrate, and organize in tubule structures is a function of selected environmental parameters. The present methodology is intended to be simple to use, standardized for rapid screening and suitable for mechanistic studies. J. Cell. Physiol. 232: 243-248, 2017. © 2016 Wiley Periodicals, Inc.

  3. Experimental evidence for the conditions necessary to sustain meandering in coarse-bedded rivers.

    PubMed

    Braudrick, Christian A; Dietrich, William E; Leverich, Glen T; Sklar, Leonard S

    2009-10-06

    Meandering rivers are common on Earth and other planetary surfaces, yet the conditions necessary to maintain meandering channels are unclear. As a consequence, self-maintaining meandering channels with cutoffs have not been reproduced in the laboratory. Such experimental channels are needed to explore mechanisms controlling migration rate, sinuosity, floodplain formation, and planform morphodynamics and to test theories for wavelength and bend propagation. Here we report an experiment in which meandering with near-constant width was maintained during repeated cutoff and regeneration of meander bends. We found that elevated bank strength (provided by alfalfa sprouts) relative to the cohesionless bed material and the blocking of troughs (chutes) in the lee of point bars via suspended sediment deposition were the necessary ingredients to successful meandering. Varying flood discharge was not necessary. Scaling analysis shows that the experimental meander migration was fast compared to most natural channels. This high migration rate caused nearly all of the bedload sediment to exchange laterally, such that bar growth was primarily dependent on bank sediment supplied from upstream lateral migration. The high migration rate may have contributed to the relatively low sinuosity of 1.19, and this suggests that to obtain much higher sinuosity experiments at this scale may have to be conducted for several years. Although patience is required to evolve them, these experimental channels offer the opportunity to explore several fundamental issues about river morphodynamics. Our results also suggest that sand supply may be an essential control in restoring self-maintaining, actively shifting gravel-bedded meanders.

  4. Experimental Evidence of Icosahedral and Decahedral Packing in One-Dimensional Nanostructures

    PubMed Central

    Velázquez-Salazar, J. Jesús; Esparza, Rodrigo; Mejía-Rosales, Sergio Javier; Estrada-Salas, Rubén; Ponce, Arturo; Deepak, Francis Leonard; Castro-Guerrero, Carlos; José-Yacamán, Miguel

    2011-01-01

    The packing of spheres is a subject that has drawn the attention of mathematicians and philosophers for centuries, and that currently attracts the interest of the scientific community in several fields. At the nanoscale, the packing of atoms affect the chemical and structural properties of the material, and hence, its potential applications. This report describes the experimental formation of five-fold nanostructures by the packing of interpenetrated icosahedral and decahedral units. These nanowires, formed by the reaction of a mixture of metal salts (Au and Ag) in the presence of oleylamine, are obtained when the chemical composition is specifically Ag/Au=3/1. The experimental images of the icosahedral nanowires have a high likelihood with simulated electron micrographs of structures formed by two or three Boerdijk-Coxeter-Bernal helices roped on a single structure, whereas for the decahedral wires, simulations using a model of adjacent decahedra match the experimental structures. To our knowledge, this is the first report of the synthesis of nanowires formed by the packing of structures with five-fold symmetry. These icosahedral nanowire structures remind those of quasicrystals that can only be formed if at least two atomic species are present and in which icosahedral and decahedral packing has been found for bulk crystals. PMID:21790155

  5. Efficient Non-Resonant Absorption of Electromagnetic Beams in Thin Cylindrical Targets: Experimental Evidence

    NASA Astrophysics Data System (ADS)

    Akhmeteli, Andrey; Kokodiy, Nikolay; Safronov, Boris; Balkashin, Valeriy; Priz, Ivan; Tarasevitch, Alexander

    2014-03-01

    A theoretical possibility of non-resonant, fast, and efficient (up to 40 percent) heating of very thin conducting cylindrical targets by broad electromagnetic beams was predicted in [Akhmeteli, arXiv:physics/0405091 and 0611169] based on rigorous solution of the diffraction problem. The diameter of the cylinder can be orders of magnitude smaller than the wavelength (for the transverse geometry) or the beam waist (for the longitudinal geometry) of the electromagnetic radiation. This can be used for numerous applications, such as pumping of active media of short-wavelength lasers, e.g., through efficient heating of nanotubes with laser radiation. Experimental confirmation of the above results is presented [Akhmeteli, Kokodiy, Safronov, Balkashin, Priz, Tarasevitch, arXiv:1109.1626 and 1208.0066]. Significant (up to 6%) absorption of microwave power focused on a thin fiber (the diameter is three orders of magnitude less than the wavelength) by an ellipsoidal reflector is demonstrated experimentally. For the longitudinal geometry, significant absorption (10%) of the power of a wide CO2 laser beam propagating along a thin wire is demonstrated experimentally (the diameter of the wire is two orders of magnitude less than the beam waist width).

  6. Virulence and molecular characterization of experimental isolates of the stripe rust pathogen (Puccinia striiformis) indicate somatic recombination

    USDA-ARS?s Scientific Manuscript database

    Puccinia striiformis causes stripe rust on wheat, barley, and grasses. Natural population studies have indicated that somatic recombination plays a possible role in the pathogen variation. To determine if somatic recombination can occur, susceptible wheat or barley plants were inoculated with mixe...

  7. The influence of iron deficiency on the functioning of skeletal muscles: experimental evidence and clinical implications.

    PubMed

    Stugiewicz, Magdalena; Tkaczyszyn, Michał; Kasztura, Monika; Banasiak, Waldemar; Ponikowski, Piotr; Jankowska, Ewa A

    2016-07-01

    Skeletal and respiratory myopathy not only constitutes an important pathophysiological feature of heart failure and chronic obstructive pulmonary disease, but also contributes to debilitating symptomatology and predicts worse outcomes in these patients. Accumulated evidence from laboratory experiments, animal models, and interventional studies in sports medicine suggests that undisturbed systemic iron homeostasis significantly contributes to the effective functioning of skeletal muscles. In this review, we discuss the role of iron status for the functioning of skeletal muscle tissue, and highlight iron deficiency as an emerging therapeutic target in chronic diseases accompanied by a marked muscle dysfunction. © 2016 The Authors. European Journal of Heart Failure © 2016 European Society of Cardiology.

  8. Experimental evidence that terrestrial carbon subsidies increase CO2 flux from lake ecosystems.

    PubMed

    Lennon, Jay T

    2004-03-01

    Subsidies are donor-controlled inputs of nutrients and energy that can affect ecosystem-level processes in a recipient environment. Lake ecosystems receive large inputs of terrestrial carbon (C) in the form of dissolved organic matter (DOM). DOM inputs may energetically subsidize heterotrophic bacteria and determine whether lakes function as sources or sinks of atmospheric CO(2). I experimentally tested this hypothesis using a series of mesocosm experiments in New England lakes. In the first experiment, I observed that CO(2) flux increased by 160% 4 days following a 1,000 microM C addition in the form of DOM. However, this response was relatively short lived, as there was no effect of DOM enrichment on CO(2) flux beyond 8 days. In a second experiment, I demonstrated that peak CO(2) flux from mesocosms in two lakes increased linearly over a broad DOM gradient (slope for both lakes=0.02+/-0.001 mM CO(2).m(-2) day(-1) per microM DOC, mean+/-SE). Concomitant changes in bacterial productivity and dissolved oxygen strengthen the inference that increasing CO(2) flux resulted from the metabolism of DOM. I conducted two additional studies to test whether DOM-correlated attributes were responsible for the observed change in plankton metabolism along the subsidy gradient. First, terrestrial DOM reduced light transmittance, but experimental shading revealed that this was not responsible for the observed patterns of CO(2) flux. Second, organically bound nitrogen (N) and phosphorus (P) accompanied DOM inputs, but experimental nutrient additions (without organic C) caused mesocosms to be saturated with CO(2). Together, these results suggest that C content of terrestrial DOM may be an important subsidy for freshwater bacteria that can influence whether recipient aquatic ecosystems are sources or sinks of atmospheric CO(2).

  9. Histological and serological evidence of experimental paracoccidioidomycosis in Calomys callosus (Rodentia: Cricetidae).

    PubMed

    Berbert, Alceu L C V; Faria, Gabriele G; Gennari-Cardoso, Margareth L; Silva, Maria M M D; Mineo, José R; Loyola, Adriano M

    2007-02-01

    The responses of animal experimental models related to the infectivity, virulence and pathogenicity of Paracoccidioides brasiliensis is constantly used to develop new perspectives of investigation. The rodent Calomys callosus, Rengger 1830 (Rodentia: Cricetidae) is an indigenous inhabitant of the savannah environment found in the central regions of Brazil. The aim of the present work was to evaluate the histopathological and serological features of C. callosus after inoculation with the Pb18 strain of P. brasiliensis. Furthermore, A/Sn and B10.A mice strains were also tested to compare the results obtained in C. callosus to these well-established experimental models of resistance and susceptibility respectively. In every instance, survival analysis was performed, and histopathological study of the lungs, liver and spleen was employed to investigate tissue involvement, degree of inflammation and fungal presence. Levels of antibodies to P. brasiliensis were measured by using an enzyme-linked immunosorbent assay after 4 weeks and at the advanced stage of infection. The mortality rate was proportional to inoculation dose in all groups, but overall it was much superior in C. callosus than in the B10.A-susceptible mice. Macroscopical and microscopical pathological alterations were also more extensive and remarkable for C. callosus, once again proportional to inoculation dose, but more noticeable differences among the studied groups were found with 0.6x10(5) inoculum. In addition, the serological profile of C. callosus was similar to that found for B10.A-susceptible mice. Infection of C. callosus with 0.6x10(8) Pb18 inoculum resulted in more serious illness, and it decreased in severity in proportion to the inoculum dose. This difference was more pronounced in C. callosus, and the clinical, serological and pathological findings in this animal were more intense and precocious compared with the B10.A-susceptible mice. The present results suggest that C. callosus is a

  10. Experimental evidence for the conditions necessary to sustain meandering in coarse-bedded rivers

    PubMed Central

    Braudrick, Christian A.; Dietrich, William E.; Leverich, Glen T.; Sklar, Leonard S.

    2009-01-01

    Meandering rivers are common on Earth and other planetary surfaces, yet the conditions necessary to maintain meandering channels are unclear. As a consequence, self-maintaining meandering channels with cutoffs have not been reproduced in the laboratory. Such experimental channels are needed to explore mechanisms controlling migration rate, sinuosity, floodplain formation, and planform morphodynamics and to test theories for wavelength and bend propagation. Here we report an experiment in which meandering with near-constant width was maintained during repeated cutoff and regeneration of meander bends. We found that elevated bank strength (provided by alfalfa sprouts) relative to the cohesionless bed material and the blocking of troughs (chutes) in the lee of point bars via suspended sediment deposition were the necessary ingredients to successful meandering. Varying flood discharge was not necessary. Scaling analysis shows that the experimental meander migration was fast compared to most natural channels. This high migration rate caused nearly all of the bedload sediment to exchange laterally, such that bar growth was primarily dependent on bank sediment supplied from upstream lateral migration. The high migration rate may have contributed to the relatively low sinuosity of 1.19, and this suggests that to obtain much higher sinuosity experiments at this scale may have to be conducted for several years. Although patience is required to evolve them, these experimental channels offer the opportunity to explore several fundamental issues about river morphodynamics. Our results also suggest that sand supply may be an essential control in restoring self-maintaining, actively shifting gravel-bedded meanders. PMID:19805077

  11. Can exercise affect the course of inflammatory bowel disease? Experimental and clinical evidence.

    PubMed

    Bilski, Jan; Mazur-Bialy, Agnieszka; Brzozowski, Bartosz; Magierowski, Marcin; Zahradnik-Bilska, Janina; Wójcik, Dagmara; Magierowska, Katarzyna; Kwiecien, Slawomir; Mach, Tomasz; Brzozowski, Tomasz

    2016-08-01

    The inflammatory bowel disease (IBD) consisting of Crohn's disease (CD) and ulcerative colitis (UC) are defined as idiopathic, chronic and relapsing intestinal disorders occurring in genetically predisposed individuals exposed to environmental risk factors such as diet and microbiome changes. Since conventional drug therapy is expensive and not fully efficient, there is a need for alternative remedies that can improve the outcome in patients suffering from IBD. Whether exercise, which has been proposed as adjunct therapy in IBD, can be beneficial in patients with IBD remains an intriguing question. In this review, we provide an overview of the effects of exercise on human IBD and experimental colitis in animal models that mimic human disease, although the information on exercise in human IBD are sparse and poorly understood. Moderate exercise can exert a beneficial ameliorating effect on IBD and improve the healing of experimental animal colitis due to the activity of protective myokines such as irisin released from working skeletal muscles. CD patients with higher levels of exercise were significantly less likely to develop active disease at six months. Moreover, voluntary exercise has been shown to exert a positive effect on IBD patients' mood, weight maintenance and osteoporosis. On the other hand, depending on its intensity and duration, exercise can evoke transient mild systemic inflammation and enhances pro-inflammatory cytokine release, thereby exacerbating the gastrointestinal symptoms. We discuss recent advances in the mechanism of voluntary and strenuous exercise affecting the outcome of IBD in patients and experimental animal models. Copyright © 2016 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  12. Histological and serological evidence of experimental paracoccidioidomycosis in Calomys callosus (Rodentia: Cricetidae)

    PubMed Central

    Berbert, Alceu LCV; Faria, Gabriele G; Gennari-Cardoso, Margareth L; Silva, Maria MMD; Mineo, José R; Loyola, Adriano M

    2007-01-01

    The responses of animal experimental models related to the infectivity, virulence and pathogenicity of Paracoccidioides brasiliensis is constantly used to develop new perspectives of investigation. The rodent Calomys callosus, Rengger 1830 (Rodentia: Cricetidae) is an indigenous inhabitant of the savannah environment found in the central regions of Brazil. The aim of the present work was to evaluate the histopathological and serological features of C. callosus after inoculation with the Pb18 strain of P. brasiliensis. Furthermore, A/Sn and B10.A mice strains were also tested to compare the results obtained in C. callosus to these well-established experimental models of resistance and susceptibility respectively. In every instance, survival analysis was performed, and histopathological study of the lungs, liver and spleen was employed to investigate tissue involvement, degree of inflammation and fungal presence. Levels of antibodies to P. brasiliensis were measured by using an enzyme-linked immunosorbent assay after 4 weeks and at the advanced stage of infection. The mortality rate was proportional to inoculation dose in all groups, but overall it was much superior in C. callosus than in the B10.A-susceptible mice. Macroscopical and microscopical pathological alterations were also more extensive and remarkable for C. callosus, once again proportional to inoculation dose, but more noticeable differences among the studied groups were found with 0.6 × 105 inoculum. In addition, the serological profile of C. callosus was similar to that found for B10.A-susceptible mice. Infection of C. callosus with 0.6 × 108 Pb18 inoculum resulted in more serious illness, and it decreased in severity in proportion to the inoculum dose. This difference was more pronounced in C. callosus, and the clinical, serological and pathological findings in this animal were more intense and precocious compared with the B10.A-susceptible mice. The present results suggest that C. callosus is a

  13. Escape of DNA from a weakly biased thin nanopore: experimental evidence for a universal diffusive behavior.

    PubMed

    Hoogerheide, David P; Albertorio, Fernando; Golovchenko, Jene A

    2013-12-13

    We report experimental escape time distributions of double-stranded DNA molecules initially threaded halfway through a thin solid-state nanopore. We find a universal behavior of the escape time distributions consistent with a one-dimensional first passage formulation notwithstanding the geometry of the experiment and the potential role of complex molecule-liquid-pore interactions. Diffusion constants that depend on the molecule length and pore size are determined. Also discussed are the practical implications of long time diffusive molecule trapping in the nanopore.

  14. Experimental evidences of a large extrinsic spin Hall effect in AuW alloy

    SciTech Connect

    Laczkowski, P.; Rojas-Sánchez, J.-C.

    2014-04-07

    We report an experimental study of a gold-tungsten alloy (7 at. % W concentration in Au host) displaying remarkable properties for spintronics applications using both magneto-transport in lateral spin valve devices and spin-pumping with inverse spin Hall effect experiments. A very large spin Hall angle of about 10% is consistently found using both techniques with the reliable spin diffusion length of 2 nm estimated by the spin sink experiments in the lateral spin valves. With its chemical stability, high resistivity, and small induced damping, this AuW alloy may find applications in the nearest future.

  15. Experimental evidence for quantum interference and vibrationally induced decoherence in single-molecule junctions.

    PubMed

    Ballmann, Stefan; Härtle, Rainer; Coto, Pedro B; Elbing, Mark; Mayor, Marcel; Bryce, Martin R; Thoss, Michael; Weber, Heiko B

    2012-08-03

    We analyze quantum interference and decoherence effects in single-molecule junctions both experimentally and theoretically by means of the mechanically controlled break junction technique and density-functional theory. We consider the case where interference is provided by overlapping quasidegenerate states. Decoherence mechanisms arising from electronic-vibrational coupling strongly affect the electrical current flowing through a single-molecule contact and can be controlled by temperature variation. Our findings underline the universal relevance of vibrations for understanding charge transport through molecular junctions.

  16. Welfare reform and child care: evidence from 10 experimental welfare-to-work programs.

    PubMed

    Robins, Philip K

    2007-10-01

    This article examines the employment and child care responses of families participating in 10 experimental welfare reform programs conducted in the United States between 1989 and 2002. For the programs analyzed, child care use increases by about the same amount as the increase in employment. Most of the increased child care comprises informal care by a relative, particularly care by a sibling or a grandparent. Although there are significant differences in the child care responses across the various programs tested, there are no significant differences in the impacts for persons leaving welfare versus persons staying on welfare.

  17. The impact of product information and trials on demand for smokeless tobacco and cigarettes: Evidence from experimental auctions

    PubMed Central

    Rousu, Matthew C.; O'Connor, Richard; Thrasher, James F; June, Kristie; Bansal-Travers, Maansi; Pitcavage, James

    2014-01-01

    Introduction Epidemiological and toxicological evidence suggests lower risk of smokeless tobacco (ST) products compared to cigarettes. Less is known, however, about consumer perceptions and use of novel forms of ST, including snus and dissolvable tobacco. Methods In this study, we conducted in-person experimental auctions in Buffalo, NY, Columbia, SC, and Selinsgrove, PA with 571 smokers to test the impact of information and product trials on smokers’ preferences. Auctions were conducted between November 2010-November 2011. Results We found no evidence of an impact of product trials on demand in our auctions. Anti-ST information increased demand for cigarettes when presented alone, but when presented with Pro-ST information it decreased demand for cigarettes. It did not decrease demand for ST products. Anti-smoking information increased demand for ST products, but did not affect cigarette demand. Conclusions These findings suggest that credible and effective communications about tobacco harm reduction should reinforce the negative effects of smoking. PMID:24321456

  18. Experimental Evidence for Anomalous Retroactive Influences on Human Cognition and Affect

    NASA Astrophysics Data System (ADS)

    Bem, Daryl J.

    2011-11-01

    Six experiments are described that take well-established psychological effects on human cognition and affect and "time-reverse" them so that the individual's responses are obtained before the putatively causal stimulus events occur. Two of the experiments tested for the retroactive facilitation of recall: It is well known that rehearsing or practicing a set of verbal materials enhances an individual's ability to recall them on a subsequent test. In our experiments, participants were first shown 48 common words one at a time and were then asked to recall as many of those words as they could. They were then given practice exercises on a randomly selected subset of those words. The results show that participants recalled more of the words they later practiced than the control words they did not practice. Two experiments on retroactive priming provide evidence for retroactive influence on an individual's response times when judging the pleasantness or unpleasantness of visual stimuli. Finally, two experiments provide evidence for the retroactive habituation to emotionally arousing visual stimuli. Each of the six experiments yielded statistically significant results, with a combined z = 3.66, p = .0001, and an effect size (d) of 0.25. The six experiments are a subset of nine retroactive influence experiments reported in Bem [1] that yielded a combined z = 6.66, p = 1.34×10-11, and an effect size of 0.22.

  19. Experimental evidence for kin-biased helping in a cooperatively breeding vertebrate.

    PubMed

    Russell, A F; Hatchwell, B J

    2001-10-22

    The widespread belief that kin selection is necessary for the evolution of cooperative breeding in vertebrates has recently been questioned. These doubts have primarily arisen because of the paucity of unequivocal evidence for kin preferences in cooperative behaviour. Using the cooperative breeding system of long-tailed tits (Aegithalos caudatus) in which kin and non-kin breed within each social unit and helpers are failed breeders, we investigated whether helpers preferentially direct their care towards kin following breeding failure. First, using observational data, we show that not all failed breeders actually become helpers, but that those that do help usually do so at the nest of a close relative. Second, we confirm the importance of kinship for helping in this species by conducting a choice experiment. We show that potential helpers do not become helpers in the absence of close kin and, when given a choice between helping equidistant broods belonging to kin and non-kin within the same social unit, virtually all helped at the nest of kin. This study provides strong evidence that kinship plays an essential role in the maintenance of cooperative breeding in this species.

  20. Understanding Counterfactuality: A Review of Experimental Evidence for the Dual Meaning of Counterfactuals

    PubMed Central

    Nieuwland, Mante S.

    2016-01-01

    Abstract Cognitive and linguistic theories of counterfactual language comprehension assume that counterfactuals convey a dual meaning. Subjunctive‐counterfactual conditionals (e.g., ‘If Tom had studied hard, he would have passed the test’) express a supposition while implying the factual state of affairs (Tom has not studied hard and failed). The question of how counterfactual dual meaning plays out during language processing is currently gaining interest in psycholinguistics. Whereas numerous studies using offline measures of language processing consistently support counterfactual dual meaning, evidence coming from online studies is less conclusive. Here, we review the available studies that examine online counterfactual language comprehension through behavioural measurement (self‐paced reading times, eye‐tracking) and neuroimaging (electroencephalography, functional magnetic resonance imaging). While we argue that these studies do not offer direct evidence for the online computation of counterfactual dual meaning, they provide valuable information about the way counterfactual meaning unfolds in time and influences successive information processing. Further advances in research on counterfactual comprehension require more specific predictions about how counterfactual dual meaning impacts incremental sentence processing. PMID:27512408