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Sample records for accumulating experimental evidence

  1. Evidence accumulation for spatial reasoning

    NASA Technical Reports Server (NTRS)

    Matsuyama, T.; Hwang, V. S. S.; Davis, L. S.

    1984-01-01

    The evidence accumulation proces of an image understanding system is described enabling the system to perform top-down(goal-oriented) picture processing as well as bottom-up verification of consistent spatial relations among objects.

  2. Accumulation and transport of microbial-size particles in a pressure protected model burn unit: CFD simulations and experimental evidence

    PubMed Central

    2011-01-01

    Background Controlling airborne contamination is of major importance in burn units because of the high susceptibility of burned patients to infections and the unique environmental conditions that can accentuate the infection risk. In particular the required elevated temperatures in the patient room can create thermal convection flows which can transport airborne contaminates throughout the unit. In order to estimate this risk and optimize the design of an intensive care room intended to host severely burned patients, we have relied on a computational fluid dynamic methodology (CFD). Methods The study was carried out in 4 steps: i) patient room design, ii) CFD simulations of patient room design to model air flows throughout the patient room, adjacent anterooms and the corridor, iii) construction of a prototype room and subsequent experimental studies to characterize its performance iv) qualitative comparison of the tendencies between CFD prediction and experimental results. The Electricité De France (EDF) open-source software Code_Saturne® (http://www.code-saturne.org) was used and CFD simulations were conducted with an hexahedral mesh containing about 300 000 computational cells. The computational domain included the treatment room and two anterooms including equipment, staff and patient. Experiments with inert aerosol particles followed by time-resolved particle counting were conducted in the prototype room for comparison with the CFD observations. Results We found that thermal convection can create contaminated zones near the ceiling of the room, which can subsequently lead to contaminate transfer in adjacent rooms. Experimental confirmation of these phenomena agreed well with CFD predictions and showed that particles greater than one micron (i.e. bacterial or fungal spore sizes) can be influenced by these thermally induced flows. When the temperature difference between rooms was 7°C, a significant contamination transfer was observed to enter into the positive

  3. Sexually antagonistic genes: experimental evidence.

    PubMed

    Rice, W R

    1992-06-01

    When selection differs between the sexes, a mutation beneficial to one sex may be harmful to the other (sexually antagonistic). Because the sexes share a common gene pool, selection in one sex can interfere with the other's adaptive evolution. Theory predicts that sexually antagonistic mutations should accumulate in tight linkage with a new sex-determining gene, even when the harm to benefit ratio is high. Genetic markers and artificial selection were used to make a pair of autosomal genes segregate like a new pair of sex-determining genes in a Drosophila melanogaster model system. A 29-generation study provides experimental evidence that sexually antagonistic genes may be common in nature and will accumulate in response to a new sex-determining gene. PMID:1604317

  4. Normative evidence accumulation in unpredictable environments

    PubMed Central

    Glaze, Christopher M; Kable, Joseph W; Gold, Joshua I

    2015-01-01

    In our dynamic world, decisions about noisy stimuli can require temporal accumulation of evidence to identify steady signals, differentiation to detect unpredictable changes in those signals, or both. Normative models can account for learning in these environments but have not yet been applied to faster decision processes. We present a novel, normative formulation of adaptive learning models that forms decisions by acting as a leaky accumulator with non-absorbing bounds. These dynamics, derived for both discrete and continuous cases, depend on the expected rate of change of the statistics of the evidence and balance signal identification and change detection. We found that, for two different tasks, human subjects learned these expectations, albeit imperfectly, then used them to make decisions in accordance with the normative model. The results represent a unified, empirically supported account of decision-making in unpredictable environments that provides new insights into the expectation-driven dynamics of the underlying neural signals. DOI: http://dx.doi.org/10.7554/eLife.08825.001 PMID:26322383

  5. Conscious and Nonconscious Processes:Distinct Forms of Evidence Accumulation?

    NASA Astrophysics Data System (ADS)

    Dehaene, Stanislas

    Among the many brain events evoked by a visual stimulus, which ones are associated specifically with conscious perception, and which merely reflect nonconscious processing? Understanding the neuronal mechanisms of consciousness is a major challenge for cognitive neuroscience. Recently, progress has been achieved by contrasting behavior and brain activation in minimally different experimental conditions, one of which leads to conscious perception whereas the other does not. This chapter reviews briefly this line of research and speculates on its theoretical interpretation. I propose to draw links between evidence accumulation models, which are highly successful in capturing elementary psychophysical decisions, and the conscious/nonconscious dichotomy. In this framework, conscious access would correspond to the crossing of a threshold in evidence accumulation within a distributed global workspace, a set of recurrently connected neurons with long axons that is able to integrate and broadcast back evidence from multiple brain processors. During nonconscious processing, evidence would be accumulated locally within specialized subcircuits, but would fail to reach the threshold needed for global ignition and, therefore, conscious reportability.

  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. Auditory Streaming as an Online Classification Process with Evidence Accumulation

    PubMed Central

    Barniv, Dana; Nelken, Israel

    2015-01-01

    When human subjects hear a sequence of two alternating pure tones, they often perceive it in one of two ways: as one integrated sequence (a single "stream" consisting of the two tones), or as two segregated sequences, one sequence of low tones perceived separately from another sequence of high tones (two "streams"). Perception of this stimulus is thus bistable. Moreover, subjects report on-going switching between the two percepts: unless the frequency separation is large, initial perception tends to be of integration, followed by toggling between integration and segregation phases. The process of stream formation is loosely named “auditory streaming”. Auditory streaming is believed to be a manifestation of human ability to analyze an auditory scene, i.e. to attribute portions of the incoming sound sequence to distinct sound generating entities. Previous studies suggested that the durations of the successive integration and segregation phases are statistically independent. This independence plays an important role in current models of bistability. Contrary to this, we show here, by analyzing a large set of data, that subsequent phase durations are positively correlated. To account together for bistability and positive correlation between subsequent durations, we suggest that streaming is a consequence of an evidence accumulation process. Evidence for segregation is accumulated during the integration phase and vice versa; a switch to the opposite percept occurs stochastically based on this evidence. During a long phase, a large amount of evidence for the opposite percept is accumulated, resulting in a long subsequent phase. In contrast, a short phase is followed by another short phase. We implement these concepts using a probabilistic model that shows both bistability and correlations similar to those observed experimentally. PMID:26671774

  8. Evidence of aluminium accumulation in aluminium welders.

    PubMed Central

    Elinder, C G; Ahrengart, L; Lidums, V; Pettersson, E; Sjögren, B

    1991-01-01

    Using atomic absorption spectrometry the aluminium concentrations in blood and urine and in two iliac bone biopsies obtained from welders with long term exposure to fumes containing aluminium were measured. The urinary excretion of two workers who had welded for 20 and 21 years varied between 107 and 351 micrograms Al/l, more than 10 times the concentration found in persons without occupational exposure. Urinary aluminium excretion remained high many years after stopping exposure. Blood and bone aluminium concentrations (4-53 micrograms Al/l and 18-29 micrograms Al/g respectively) were also raised but not to the same extent as urine excretion. It is concluded that long term exposure to aluminium by inhalation gives rise to accumulation of aluminium in the body and skeleton of health persons, and that the elimination of retained aluminium is very slow, in the order of several years. PMID:1954151

  9. Distinct relationships of parietal and prefrontal cortices to evidence accumulation

    PubMed Central

    Hanks, Timothy; Kopec, Charles D.; Brunton, Bingni W.; Duan, Chunyu A.; Erlich, Jeffrey C.; Brody, Carlos D.

    2014-01-01

    Gradual accumulation of evidence is thought to be fundamental for decision-making, and its neural correlates have been found in multiple brain regions1–8. Here we develop a generalizable method to measure tuning curves that specify the relationship between neural responses and mentally-accumulated evidence, and apply it to distinguish the encoding of decision variables in posterior parietal cortex (PPC) and prefrontal cortex (frontal orienting fields, FOF). We recorded the firing rates of neurons in PPC and FOF from rats performing a perceptual decision-making task. Classical analyses uncovered correlates of accumulating evidence, similar to previous observations in primates and also similar across the two regions. However, tuning curve assays revealed that while the PPC encodes a graded value of the accumulating evidence, the FOF has a more categorical encoding that indicates, throughout the trial, the decision provisionally favored by the evidence accumulated so far. Contrary to current views3,5,7–9, this suggests that premotor activity in frontal cortex does not play a role in the accumulation process, but instead has a more categorical function, such as transforming accumulated evidence into a discrete choice. To causally probe the role of FOF activity, we optogenetically silenced it during different timepoints of the trial. Consistent with a role in committing to a categorical choice at the end of the evidence accumulation process, but not consistent with a role during the accumulation itself, a behavioral effect was observed only when FOF silencing occurred at the end of the perceptual stimulus. Our results place important constraints on the circuit logic of brain regions involved in decision-making. PMID:25600270

  10. Neural evidence accumulation persists after choice to inform metacognitive judgments

    PubMed Central

    Murphy, Peter R; Robertson, Ian H; Harty, Siobhán; O'Connell, Redmond G

    2015-01-01

    The ability to revise one’s certainty or confidence in a preceding choice is a critical feature of adaptive decision-making but the neural mechanisms underpinning this metacognitive process have yet to be characterized. In the present study, we demonstrate that the same build-to-threshold decision variable signal that triggers an initial choice continues to evolve after commitment, and determines the timing and accuracy of self-initiated error detection reports by selectively representing accumulated evidence that the preceding choice was incorrect. We also show that a peri-choice signal generated in medial frontal cortex provides a source of input to this post-decision accumulation process, indicating that metacognitive judgments are not solely based on the accumulation of feedforward sensory evidence. These findings impart novel insights into the generative mechanisms of metacognition. DOI: http://dx.doi.org/10.7554/eLife.11946.001 PMID:26687008

  11. Active inference, evidence accumulation and the urn task

    PubMed Central

    FitzGerald, Thomas HB; Schwartenbeck, Philipp; Moutoussis, Michael; Dolan, Raymond J; Friston, Karl

    2015-01-01

    Deciding how much evidence to accumulate before making a decision is a problem we and other animals often face, but one which is not completely understood. This issue is particularly important because a tendency to sample less information (often known as reflection impulsivity) is a feature in several psychopathologies, such as psychosis. A formal understanding information sampling may therefore clarify the computational anatomy of psychopathology. In this theoretical paper, we consider evidence accumulation in terms of active (Bayesian) inference using a generic model of Markov decision processes. Here, agents are equipped with beliefs about their own behaviour – in this case, that they will make informed decisions. Normative decision-making is then modelled using variational Bayes to minimise surprise about choice outcomes. Under this scheme, different facets of belief updating map naturally onto the functional anatomy of the brain (at least at a heuristic level). Of particular interest is the key role played by the expected precision of beliefs about control, which we have previously suggested may be encoded by dopaminergic neurons in the midbrain. We show that manipulating expected precision strongly affects how much information an agent characteristically samples, and thus provides a possible link between impulsivity and dopaminergic dysfunction. Our study therefore represents a step towards understanding evidence accumulation in terms of neurobiologically plausible Bayesian inference, and may cast light on why this process is disordered in psychopathology. PMID:25514108

  12. Is There Neural Evidence for an Evidence Accumulation Process in Memory Decisions?

    PubMed Central

    van Vugt, Marieke K.; Beulen, Marijke A.; Taatgen, Niels A.

    2016-01-01

    Models of evidence accumulation have been very successful at describing human decision making behavior. Recent years have also seen the first reports of neural correlates of this accumulation process. However, these studies have mostly focused on perceptual decision making tasks, ignoring the role of additional cognitive processes like memory retrieval that are crucial in real-world decisions. In this study, we tried to find a neural signature of evidence accumulation during a recognition memory task. To do this, we applied a method we have successfully used to localize evidence accumulation in scalp EEG during a perceptual decision making task. This time, however, we applied it to intracranial EEG recordings, which provide a much higher spatial resolution. We identified several brain areas where activity ramps up over time, but these neural patterns do not appear to be modulated by behavioral variables such as the amount of available evidence or response time. This casts doubt on the idea of evidence accumulation as a general decision-making mechanism underlying different types of decisions. PMID:27014024

  13. What is value—accumulated reward or evidence?

    PubMed Central

    Friston, Karl; Adams, Rick; Montague, Read

    2012-01-01

    Why are you reading this abstract? In some sense, your answer will cast the exercise as valuable—but what is value? In what follows, we suggest that value is evidence or, more exactly, log Bayesian evidence. This implies that a sufficient explanation for valuable behavior is the accumulation of evidence for internal models of our world. This contrasts with normative models of optimal control and reinforcement learning, which assume the existence of a value function that explains behavior, where (somewhat tautologically) behavior maximizes value. In this paper, we consider an alternative formulation—active inference—that replaces policies in normative models with prior beliefs about the (future) states agents should occupy. This enables optimal behavior to be cast purely in terms of inference: where agents sample their sensorium to maximize the evidence for their generative model of hidden states in the world, and minimize their uncertainty about those states. Crucially, this formulation resolves the tautology inherent in normative models and allows one to consider how prior beliefs are themselves optimized in a hierarchical setting. We illustrate these points by showing that any optimal policy can be specified with prior beliefs in the context of Bayesian inference. We then show how these prior beliefs are themselves prescribed by an imperative to minimize uncertainty. This formulation explains the saccadic eye movements required to read this text and defines the value of the visual sensations you are soliciting. PMID:23133414

  14. In vivo experimental evidence that the major metabolites accumulating in 3-hydroxy-3-methylglutaryl-CoA lyase deficiency induce oxidative stress in striatum of developing rats: a potential pathophysiological mechanism of striatal damage in this disorder.

    PubMed

    Fernandes, Carolina Gonçalves; da Rosa, Mateus Struecker; Seminotti, Bianca; Pierozan, Paula; Martell, Rafael Wolter; Lagranha, Valeska Lizzi; Busanello, Estela Natacha Brandt; Leipnitz, Guilhian; Wajner, Moacir

    2013-06-01

    3-Hydroxy-3-methylglutaryl-CoA lyase (HL) deficiency is a genetic disorder biochemically characterized by predominant accumulation of 3-hydroxy-3-methylglutaric (HMG) and 3-methylglutaric (MGA) acids in tissues and biological fluids of affected individuals. Clinically, the patients present neurological symptoms and basal ganglia injury, whose pathomechanisms are partially understood. In the present study, we investigated the ex vivo effects of intrastriatal administration of HMG and MGA on important parameters of oxidative stress in striatum of developing rats. Our results demonstrate that HMG and MGA induce lipid and protein oxidative damage. HMG and MGA also increased 2',7'-dichlorofluorescein oxidation, whereas only HMG elicited nitric oxide production, indicating a role for reactive oxygen (HMG and MGA) and nitrogen (HMG) species in these effects. Regarding the enzymatic antioxidant defenses, both organic acids decreased reduced glutathione concentrations and the activities of superoxide dismutase and glutathione reductase and increased glutathione peroxidase activity. HMG also provoked an increase of catalase activity and a diminution of glucose-6-phosphate dehydrogenase activity. We finally observed that antioxidants fully prevented or attenuated HMG-induced alterations of the oxidative stress parameters, further indicating the participation of reactive species in these effects. We also observed that MK-801, a non-competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, prevented some of these effects, indicating the involvement of the NMDA receptor in HMG effects. The present data provide solid evidence that oxidative stress is induced in vivo by HMG and MGA in rat striatum and it is presumed that this pathomechanism may explain, at least in part, the cerebral alterations observed in HL deficiency. PMID:23611578

  15. Loess is the accumulation of dust, not evidence for aridity

    NASA Astrophysics Data System (ADS)

    Zech, Roland

    2013-04-01

    Loess-paleosol sequences (LPS) are valuable terrestrial archives for Quaternary climate and environmental changes. The famous sections on the Chinese Loess Plateau, for example, document the alternation of warm and humid interglacials (paleosols) and cold and more arid glacials (loess). This, at least partly, reflects the weakening of the monsoonal circulation during glacials and has led to the notion that loess in general documents more arid conditions. Paleosols, on the other hand, are often interpreted to document more humid conditions. We studied the LPS Crvenka in the Carpathian Basin, southeast Europe, which spans the full last glacial cycle, and obtained results that do not fit the above concept: (i) The analysis of plant-derived long-chain n-alkanes indicates the presence of deciduous trees and shrubs during glacials, i.e. sufficient precipitation for tree growth, whereas tree-less grass steppes seem to have prevailed during the Eemian, the last interglacial. (ii) Compound-specific deuterium analyses on the alkanes show only little changes on glacial-interglacial timescale. When compared with the isotopic enrichment of the Mediterranean Sea during the last glacial, this likely documents a combination of increased rainfall, reduced evapo-transpiration and reduced temperatures. (iii) Novel lipid biomarkers derived from soil bacteria (GDGTs, glycerol dialkyl glycerol tetraethers) also indicate humid glacials (BIT index close to 1) and more arid interglacials (BIT<0.8). Our results are in good agreement with modelling studies suggesting a southward shift of the westerlies during glacials, and aridization in the Mediterranean area in response to man-made global warming. More importantly, they remind us of an important fact: Loess is the accumulation of dust, but not (necessarily) evidence for aridity. Pedogenesis may simply not have been able to keep pace with high glacial dust accumulation rates related to intense glacial, periglacial and fluvial activity

  16. Cadmium as a possible cause of bladder cancer: a review of accumulated evidence.

    PubMed

    Feki-Tounsi, Molka; Hamza-Chaffai, Amel

    2014-09-01

    Bladder cancer is a significant disease, the rates of which have increased over the few last years. However, its etiology remains as yet undefined. Cadmium, a widespread environmental carcinogen that has received considerable interest, presents evidence as a possible cause of bladder cancer. A literature review was conducted from the years 1984-2013 to study the accumulated evidence for cadmium as a possible cause of bladder cancer, including routes of cadmium exposure, accumulation, toxicity, carcinogenicity, and evidence from epidemiological and experimental studies. Special reference is devoted to cadmium nephrotoxicity, which illustrates how cadmium exerts its effects on the transitional epithelium of the urinary tract. Mechanisms of carcinogenesis are discussed. The effects of cadmium on gene expression in urothelial cells exposed to cadmium are also addressed. Despite different methodologies, several epidemiologic and nephrotoxicity studies of cadmium indicate that occupational exposure to cadmium is associated with increased risk of bladder cancer and provide additional evidence that cadmium is a potential toxic element in urothelial cells. In vitro studies provide further evidence that cadmium is involved in urothelial carcinogenesis. Animal studies encounter several problems such as morphology differences between species. Among the complex mechanisms of cadmium carcinogenesis, gene expression deregulation is the subject of recent studies on bladder cadmium-induced carcinogenesis. Further research, however, will be required to promise a better understanding of the mechanisms underlying cadmium carcinogenesis and to establish the precise role of cadmium in this important malignancy. PMID:24894749

  17. Experimental evidence of quantum randomness incomputability

    SciTech Connect

    Calude, Cristian S.; Dinneen, Michael J.; Dumitrescu, Monica; Svozil, Karl

    2010-08-15

    In contrast with software-generated randomness (called pseudo-randomness), quantum randomness can be proven incomputable; that is, it is not exactly reproducible by any algorithm. We provide experimental evidence of incomputability--an asymptotic property--of quantum randomness by performing finite tests of randomness inspired by algorithmic information theory.

  18. 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.

  19. Evidence Accumulation and Choice Maintenance Are Dissociated in Human Perceptual Decision Making.

    PubMed

    Pedersen, Mads Lund; Endestad, Tor; Biele, Guido

    2015-01-01

    Perceptual decision making in monkeys relies on decision neurons, which accumulate evidence and maintain choices until a response is given. In humans, several brain regions have been proposed to accumulate evidence, but it is unknown if these regions also maintain choices. To test if accumulator regions in humans also maintain decisions we compared delayed and self-paced responses during a face/house discrimination decision making task. Computational modeling and fMRI results revealed dissociated processes of evidence accumulation and decision maintenance, with potential accumulator activations found in the dorsomedial prefrontal cortex, right inferior frontal gyrus and bilateral insula. Potential maintenance activation spanned the frontal pole, temporal gyri, precuneus and the lateral occipital and frontal orbital cortices. Results of a quantitative reverse inference meta-analysis performed to differentiate the functions associated with the identified regions did not narrow down potential accumulation regions, but suggested that response-maintenance might rely on a verbalization of the response. PMID:26510176

  20. Demystifying "free will": the role of contextual information and evidence accumulation for predictive brain activity.

    PubMed

    Bode, Stefan; Murawski, Carsten; Soon, Chun Siong; Bode, Philipp; Stahl, Jutta; Smith, Philip L

    2014-11-01

    Novel multivariate pattern classification analyses have enabled the prediction of decision outcomes from brain activity prior to decision-makers' reported awareness. These findings are often discussed in relation to the philosophical concept of "free will". We argue that these studies demonstrate the role of unconscious processes in simple free choices, but they do not inform the philosophical debate. Moreover, these findings are difficult to relate to cognitive decision-making models, due to misleading assumptions about random choices. We review evidence suggesting that sequential-sampling models, which assume accumulation of evidence towards a decision threshold, can also be applied to free decisions. If external evidence is eliminated by the task instructions, decision-makers might use alternative, subtle contextual information as evidence, such as their choice history, that is not consciously monitored and usually concealed by the experimental design. We conclude that the investigation of neural activity patterns associated with free decisions should aim to investigate how decisions are jointly a function of internal and external contexts, rather than to resolve the philosophical "free will" debate. PMID:25452111

  1. Expression of iron homeostasis proteins in the spinal cord in experimental autoimmune encephalomyelitis and their implications for iron accumulation.

    PubMed

    Zarruk, Juan G; Berard, Jennifer L; Passos dos Santos, Rosmarini; Kroner, Antje; Lee, Jaekwon; Arosio, Paolo; David, Samuel

    2015-09-01

    Iron accumulation occurs in the CNS in multiple sclerosis (MS) and in experimental autoimmune encephalomyelitis (EAE). However, the mechanisms underlying such iron accumulation are not fully understood. We studied the expression and cellular localization of molecules involved in cellular iron influx, storage, and efflux. This was assessed in two mouse models of EAE: relapsing-remitting (RR-EAE) and chronic (CH-EAE). The expression of molecules involved in iron homeostasis was assessed at the onset, peak, remission/progressive and late stages of the disease. We provide several lines of evidence for iron accumulation in the EAE spinal cord which increases with disease progression and duration, is worse in CH-EAE, and is localized in macrophages and microglia. We also provide evidence that there is a disruption of the iron efflux mechanism in macrophages/microglia that underlie the iron accumulation seen in these cells. Macrophages/microglia also lack expression of the ferroxidases (ceruloplasmin and hephaestin) which have antioxidant effects. In contrast, astrocytes which do not accumulate iron, show robust expression of several iron influx and efflux proteins and the ferroxidase ceruloplasmin which detoxifies ferrous iron. Astrocytes therefore are capable of efficiently recycling iron from sites of EAE lesions likely into the circulation. We also provide evidence of marked dysregulation of mitochondrial function and energy metabolism genes, as well as of NADPH oxidase genes in the EAE spinal cord. This data provides the basis for the selective iron accumulation in macrophage/microglia and further evidence of severe mitochondrial dysfunction in EAE. It may provide insights into processes underling iron accumulation in MS and other neurodegenerative diseases in which iron accumulation occurs. PMID:25724358

  2. Action Planning and the Timescale of Evidence Accumulation

    PubMed Central

    Donner, Tobias H.

    2015-01-01

    Perceptual decisions are based on the temporal integration of sensory evidence for different states of the outside world. The timescale of this integration process varies widely across behavioral contexts and individuals, and it is diagnostic for the underlying neural mechanisms. In many situations, the decision-maker knows the required mapping between perceptual evidence and motor response (henceforth termed “sensory-motor contingency”) before decision formation. Here, the integrated evidence can be directly translated into a motor plan and, indeed, neural signatures of the integration process are evident as build-up activity in premotor brain regions. In other situations, however, the sensory-motor contingencies are unknown at the time of decision formation. We used behavioral psychophysics and computational modeling to test if knowledge about sensory-motor contingencies affects the timescale of perceptual evidence integration. We asked human observers to perform the same motion discrimination task, with or without trial-to-trial variations of the mapping between perceptual choice and motor response. When the mapping varied, it was either instructed before or after the stimulus presentation. We quantified the timescale of evidence integration under these different sensory-motor mapping conditions by means of two approaches. First, we analyzed subjects’ discrimination threshold as a function of stimulus duration. Second, we fitted a dynamical decision-making model to subjects’ choice behavior. The results from both approaches indicated that observers (i) integrated motion information for several hundred ms, (ii) used a shorter than optimal integration timescale, and (iii) used the same integration timescale under all sensory-motor mappings. We conclude that the mechanisms limiting the timescale of perceptual decisions are largely independent from long-term learning (under fixed mapping) or rapid acquisition (under variable mapping) of sensory

  3. EXPERIMENTAL METHODS TO ESTIMATE ACCUMULATED SOLIDS IN NUCLEAR WASTE TANKS

    SciTech Connect

    Duignan, M.; Steeper, T.; Steimke, J.

    2012-12-10

    The Department of Energy has a large number of nuclear waste tanks. It is important to know if fissionable materials can concentrate when waste is transferred from staging tanks prior to feeding waste treatment plants. Specifically, there is a concern that large, dense particles, e.g., plutonium containing, could accumulate in poorly mixed regions of a blend tank heel for tanks that employ mixing jet pumps. At the request of the DOE Hanford Tank Operations Contractor, Washington River Protection Solutions, the Engineering Development Laboratory of the Savannah River National Laboratory performed a scouting study in a 1/22-scale model of a waste tank to investigate this concern and to develop measurement techniques that could be applied in a more extensive study at a larger scale. Simulated waste tank solids and supernatant were charged to the test tank and rotating liquid jets were used to remove most of the solids. Then the volume and shape of the residual solids and the spatial concentration profiles for the surrogate for plutonium were measured. This paper discusses the overall test results, which indicated heavy solids only accumulate during the first few transfer cycles, along with the techniques and equipment designed and employed in the test. Those techniques include: Magnetic particle separator to remove stainless steel solids, the plutonium surrogate from a flowing stream; Magnetic wand used to manually remove stainless steel solids from samples and the tank heel; Photographs were used to determine the volume and shape of the solids mounds by developing a composite of topographical areas; Laser rangefinders to determine the volume and shape of the solids mounds; Core sampler to determine the stainless steel solids distribution within the solids mounds; Computer driven positioner that placed the laser rangefinders and the core sampler over solids mounds that accumulated on the bottom of a scaled staging tank in locations where jet velocities were low. These

  4. Respirators versus medical masks: evidence accumulates but the jury remains out

    PubMed Central

    Killingley, Ben

    2011-01-01

    Please cite this paper as: Killingley (2011). Respiratory versus medical masks: evidence accumulates but the jury remains out. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2011.00237.x. PMID:21477131

  5. Lipid accumulation in prosthetic vascular grafts. Experimental study.

    PubMed Central

    Chignier, E.; Guidollet, J.; Lhopital, C.; Louisot, P.; Eloy, R.

    1990-01-01

    The present study demonstrates that the endoprosthetic tissue, developed at the contact of Dacron and Gore-Tex vascular prostheses replacing the infrarenal aortae of healthy dogs, presents a particular lipidic pattern as compared with the adjacent intimal arterial layer. The modified lipidic pattern is characterized by a significant increase in the total amounts of cholesterol, phospholipids, and triglycerides, despite a normal lipidic plasma profile. Histochemical studies showed that lipid droplets are accumulated in the cytoplasm of deeply situated cells and in the extracellular matrix. These findings support the idea that lipids may be trapped within the pseudo-intima of synthetic vascular grafts, even in the absence of a major plasma lipid disorder, and contribute to the prosthesis failure. Images Figure 2 Figure 4 Figure 5 Figure 6 PMID:2399933

  6. An experimental investigation of nonresonance photon accumulation in a system of spherical mirrors

    NASA Astrophysics Data System (ADS)

    Popov, S. S.; Atlukhanov, M. G.; Burdakov, A. V.; Ushkova, M. Yu.

    2016-07-01

    A new, nonresonant approach to photon accumulation in a system of two spherical mirrors is demonstrated experimentally. A high accumulation coefficient is obtained experimentally, and sufficient efficiency of this technique for application in such areas as spectroscopy, photochemistry, and photon neutralization of negative-ion beams is demonstrated. The photon accumulation efficiency is determined mainly by mirror reflectivity. It is nearly independent of the quality of the coupled-in radiation and does not require very high precision in aligning optical elements. The experimentally obtained data agree with theoretical calculations.

  7. Accumulation of cadmium in a freshwater food chain experimental model.

    PubMed

    Ferard, J F; Jouany, J M; Truhaut, R; Vasseur, P

    1983-02-01

    The study of food chain contamination in nature or in the laboratory requires precise definitions of some terms. A simplified model of a freshwater food chain has been elaborated to try to point out hazards related to the presence of cadmium in the aquatic environment. Three different species belonging to various trophic levels, but to the same aquatic systems were used. The required biological and analytical criteria are described. The time course of the experiment was 34 days starting with a 10-day contamination of the first trophic level (algae). The algae were then separated, washed with fresh medium, and given to the second trophic level (daphnids) to eat for 20 days. The third trophic level (fish) was then introduced for 4 days as a scavenger. The methodology was designed to determine the accumulation of cadmium by daphnids and then fish from the algal source. The results show a high direct bioaccumulation of cadmium in algae. The indirect bioaccumulation of daphnids was of the same order of magnitude, but for fish it was smaller. Nevertheless the cadmium transfer from daphnids to fish was obvious. PMID:6851925

  8. Experimental Evidence on Iterated Reasoning in Games

    PubMed Central

    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. PMID:26312486

  9. Perception as Evidence Accumulation and Bayesian Inference: Insights from Masked Priming

    ERIC Educational Resources Information Center

    Norris, Dennis; Kinoshita, Sachiko

    2008-01-01

    The authors argue that perception is Bayesian inference based on accumulation of noisy evidence and that, in masked priming, the perceptual system is tricked into treating the prime and the target as a single object. Of the 2 algorithms considered for formalizing how the evidence sampled from a prime and target is combined, only 1 was shown to be…

  10. Interference effects of choice on confidence: Quantum characteristics of evidence accumulation.

    PubMed

    Kvam, Peter D; Pleskac, Timothy J; Yu, Shuli; Busemeyer, Jerome R

    2015-08-25

    Decision-making relies on a process of evidence accumulation which generates support for possible hypotheses. Models of this process derived from classical stochastic theories assume that information accumulates by moving across definite levels of evidence, carving out a single trajectory across these levels over time. In contrast, quantum decision models assume that evidence develops over time in a superposition state analogous to a wavelike pattern and that judgments and decisions are constructed by a measurement process by which a definite state of evidence is created from this indefinite state. This constructive process implies that interference effects should arise when multiple responses (measurements) are elicited over time. We report such an interference effect during a motion direction discrimination task. Decisions during the task interfered with subsequent confidence judgments, resulting in less extreme and more accurate judgments than when no decision was elicited. These results provide qualitative and quantitative support for a quantum random walk model of evidence accumulation over the popular Markov random walk model. We discuss the cognitive and neural implications of modeling evidence accumulation as a quantum dynamic system. PMID:26261322

  11. Rhythmic fluctuations in evidence accumulation during decision making in the human brain

    PubMed Central

    Wyart, Valentin; de Gardelle, Vincent; Scholl, Jacqueline; Summerfield, Christopher

    2014-01-01

    Summary Categorical choices are preceded by the accumulation of sensory evidence in favour of one action or another. Current models describe evidence accumulation as a continuous process occurring at a constant rate, but this view is inconsistent with accounts of a psychological refractory period during sequential information processing. During multi-sample perceptual categorisation, we found that the neural encoding of momentary evidence in human electrical brain signals and its subsequent impact on choice fluctuated rhythmically according to the phase of ongoing parietal delta oscillations (1-3 Hz). By contrast, lateralised beta-band power (10-30 Hz) overlying human motor cortex encoded the integrated evidence as a response preparation signal. These findings draw a clear distinction between central and motor stages of perceptual decision making, with successive samples of sensory evidence competing to pass through a serial processing bottleneck before being mapped onto action. PMID:23177968

  12. 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.

  13. Content-specific evidence accumulation in inferior temporal cortex during perceptual decision-making

    PubMed Central

    Tremel, Joshua J.; Wheeler, Mark E.

    2015-01-01

    During a perceptual decision, neuronal activity can change as a function of time-integrated evidence. Such neurons may serve as decision variables, signaling a choice when activity reaches a boundary. Because the signals occur on a millisecond timescale, translating to human decision-making using functional neuroimaging has been challenging. Previous neuroimaging work in humans has identified patterns of neural activity consistent with an accumulation account. However, the degree to which the accumulating neuroimaging signals reflect specific sources of perceptual evidence is unknown. Using an extended face/house discrimination task in conjunction with cognitive modeling, we tested whether accumulation signals, as measured using functional magnetic resonance imaging (fMRI), are stimulus-specific. Accumulation signals were defined as a change in the slope of the rising edge of activation corresponding with response time (RT), with higher slopes associated with faster RTs. Consistent with an accumulation account, fMRI activity in face- and house-selective regions in the inferior temporal cortex increased at a rate proportional to decision time in favor of the preferred stimulus. This finding indicates that stimulus-specific regions perform an evidence integrative function during goal-directed behavior and that different sources of evidence accumulate separately. We also assessed the decision-related function of other regions throughout the brain and found that several regions were consistent with classifications from prior work, suggesting a degree of domain generality in decision processing. Taken together, these results provide support for an integration-to-boundary decision mechanism and highlight possible roles of both domain-specific and domain-general regions in decision evidence evaluation. PMID:25562821

  14. Sources of noise during accumulation of evidence in unrestrained and voluntarily head-restrained rats.

    PubMed

    Scott, Benjamin B; Constantinople, Christine M; Erlich, Jeffrey C; Tank, David W; Brody, Carlos D

    2015-01-01

    Decision-making behavior is often characterized by substantial variability, but its source remains unclear. We developed a visual accumulation of evidence task designed to quantify sources of noise and to be performed during voluntary head restraint, enabling cellular resolution imaging in future studies. Rats accumulated discrete numbers of flashes presented to the left and right visual hemifields and indicated the side that had the greater number of flashes. Using a signal-detection theory-based model, we found that the standard deviation in their internal estimate of flash number scaled linearly with the number of flashes. This indicates a major source of noise that, surprisingly, is not consistent with the widely used 'drift-diffusion modeling' (DDM) approach but is instead closely related to proposed models of numerical cognition and counting. We speculate that this form of noise could be important in accumulation of evidence tasks generally. PMID:26673896

  15. Distinct effects of prefrontal and parietal cortex inactivations on an accumulation of evidence task in the rat.

    PubMed

    Erlich, Jeffrey C; Brunton, Bingni W; Duan, Chunyu A; Hanks, Timothy D; Brody, Carlos D

    2015-01-01

    Numerous brain regions have been shown to have neural correlates of gradually accumulating evidence for decision-making, but the causal roles of these regions in decisions driven by accumulation of evidence have yet to be determined. Here, in rats performing an auditory evidence accumulation task, we inactivated the frontal orienting fields (FOF) and posterior parietal cortex (PPC), two rat cortical regions that have neural correlates of accumulating evidence and that have been proposed as central to decision-making. We used a detailed model of the decision process to analyze the effect of inactivations. Inactivation of the FOF induced substantial performance impairments that were quantitatively best described as an impairment in the output pathway of an evidence accumulator with a long integration time constant (>240 ms). In contrast, we found a minimal role for PPC in decisions guided by accumulating auditory evidence, even while finding a strong role for PPC in internally-guided decisions. PMID:25869470

  16. Evidence accumulation in a complex task: Making choices about concurrent multiattribute stimuli under time pressure.

    PubMed

    Palada, Hector; Neal, Andrew; Vuckovic, Anita; Martin, Russell; Samuels, Kate; Heathcote, Andrew

    2016-03-01

    Evidence accumulation models transform observed choices and associated response times into psychologically meaningful constructs such as the strength of evidence and the degree of caution. Standard versions of these models were developed for rapid (∼1 s) choices about simple stimuli, and have recently been elaborated to some degree to address more complex stimuli and response methods. However, these elaborations can be difficult to use with designs and measurements typically encountered in complex applied settings. We test the applicability of 2 standard accumulation models-the diffusion (Ratcliff & McKoon, 2008) and the linear ballistic accumulation (LBA) (Brown & Heathcote, 2008)-to data from a task representative of many applied situations: the detection of heterogeneous multiattribute targets in a simulated unmanned aerial vehicle (UAV) operator task. Despite responses taking more than 2 s and complications added by realistic features, such as a complex target classification rule, interruptions from a simultaneous UAV navigation task, and time pressured choices about several concurrently present potential targets, these models performed well descriptively. They also provided a coherent psychological explanation of the effects of decision uncertainty and workload manipulations. Our results support the wider application of standard evidence accumulation models to applied decision-making settings. PMID:26844369

  17. 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.

  18. Screening for insect and disease resistance and aflatoxin accumulation in experimental maize hybrids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to develop new maize germplasm lines with resistance to multiple insect pests, disease, and aflatoxin accumulation in temperate region, a set of new experimental hybrids was made using exotic tropical and subtropical maize inbred lines. The evaluation of these breeding crosses for insect a...

  19. Ultrastructural evidence for iron accumulation within the tube of Vestimentiferan Ridgeia piscesae.

    PubMed

    Peng, Xiaotong; Zhou, Huaiyang; Yao, Huiqiang; Li, Jiangtao; Wu, Zijun

    2009-10-01

    This study reports on the accumulation of iron within the tube wall of the deep sea vent macro invertebrate Vestimentiferan Ridgeia piscesae collected from Juan de Fuca ridge. Combining an array of approaches including environmental scanning electron microscope (ESEM), electron probe micro-analysis (EPMA), X-ray microanalysis (EDS) and transmission electron microscope (TEM), we provide evidences for the influence of prokaryotic organisms on the accumulation of metals on and within the tube wall. Two types of iron-rich minerals such as iron oxides and framboidal pyrites are identified within or on the tube wall. Our results reveal the presence of prokaryotic organism is apparently responsible for the early accumulation of iron-rich minerals in the tube wall. The implications of the biomineralisation of iron in tube wall at hydrothermal vents are discussed. PMID:19199091

  20. 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

  1. 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.

  2. Blockage of mitochondrial calcium uniporter prevents iron accumulation in a model of experimental subarachnoid hemorrhage

    SciTech Connect

    Yan, Huiying; Hao, Shuangying; Sun, Xiaoyan; Zhang, Dingding; Gao, Xin; Yu, Zhuang; Li, Kuanyu; Hang, Chun-Hua

    2015-01-24

    Highlights: • Iron accumulation was involved in the acute phase following SAH. • Blockage of MCU could attenuate cellular iron accumulation following SAH. • Blockage of MCU could decrease ROS generation and improve cell energy supply following SAH. • Blockage of MCU could alleviate apoptosis and brain injury following SAH. - Abstract: Previous studies have shown that iron accumulation is involved in the pathogenesis of brain injury following subarachnoid hemorrhage (SAH) and chelation of iron reduced mortality and oxidative DNA damage. We previously reported that blockage of mitochondrial calcium uniporter (MCU) provided benefit in the early brain injury after experimental SAH. This study was undertaken to identify whether blockage of MCU could ameliorate iron accumulation-associated brain injury following SAH. Therefore, we used two reagents ruthenium red (RR) and spermine (Sper) to inhibit MCU. Sprague–Dawley (SD) rats were randomly divided into four groups including sham, SAH, SAH + RR, and SAH + Sper. Biochemical analysis and histological assays were performed. The results confirmed the iron accumulation in temporal lobe after SAH. Interestingly, blockage of MCU dramatically reduced the iron accumulation in this area. The mechanism was revealed that inhibition of MCU reversed the down-regulation of iron regulatory protein (IRP) 1/2 and increase of ferritin. Iron–sulfur cluster dependent-aconitase activity was partially conserved when MCU was blocked. In consistence with this and previous report, ROS levels were notably reduced and ATP supply was rescued; levels of cleaved caspase-3 dropped; and integrity of neurons in temporal lobe was protected. Taken together, our results indicated that blockage of MCU could alleviate iron accumulation and the associated injury following SAH. These findings suggest that the alteration of calcium and iron homeostasis be coupled and MCU be considered to be a therapeutic target for patients suffering from SAH.

  3. Simulation and experimental research for piping damper with plunger-type accumulator

    NASA Astrophysics Data System (ADS)

    Luo, Xiao-Hui; Hu, Jun-Hua; Wang, Xiao-Bin; Niu, Zi-Hua

    2010-09-01

    It can be beneficial to reduce vibrations in shipboard piping, so the authors designed a new kind of piping damper with a plunger-type accumulator. Special requirements for the piping damper included low impact displacement, low speed, as well as an appropriate locking speed. Inside the damper, a plunger-type accumulator was installed and on the outside of the piston rod, a tube with exposed corrugations was added. Between the piston and the cylinder, a clearance seal was added. Using mathematical modeling, the effects of the dynamic performance of the damper’s impact displacement on vibrations were observed. Changes to the clearance between the piston and the cylinder, the stiffness of the spring in the accumulator, the throttle valve size, and locking speed resistance of the damper were respectively simulated and studied. Based on the results of the simulation, dampers with optimal parameters were developed and tested with different accumulator spring stiffnesses and different throttles. The simulation and experimental results showed that parameters such as seal clearance between piston and cylinder, accumulator spring stiffness and throttle parameters have significant effects on the damper’s impact displacement, low speed resistance and locking speed.

  4. Sources of noise during accumulation of evidence in unrestrained and voluntarily head-restrained rats

    PubMed Central

    Scott, Benjamin B; Constantinople, Christine M; Erlich, Jeffrey C; Tank, David W; Brody, Carlos D

    2015-01-01

    Decision-making behavior is often characterized by substantial variability, but its source remains unclear. We developed a visual accumulation of evidence task designed to quantify sources of noise and to be performed during voluntary head restraint, enabling cellular resolution imaging in future studies. Rats accumulated discrete numbers of flashes presented to the left and right visual hemifields and indicated the side that had the greater number of flashes. Using a signal-detection theory-based model, we found that the standard deviation in their internal estimate of flash number scaled linearly with the number of flashes. This indicates a major source of noise that, surprisingly, is not consistent with the widely used 'drift-diffusion modeling' (DDM) approach but is instead closely related to proposed models of numerical cognition and counting. We speculate that this form of noise could be important in accumulation of evidence tasks generally. DOI: http://dx.doi.org/10.7554/eLife.11308.001 PMID:26673896

  5. The nitrogen legacy: emerging evidence of nitrogen accumulation in anthropogenic landscapes

    NASA Astrophysics Data System (ADS)

    Van Meter, K. J.; Basu, N. B.; Veenstra, J. J.; Burras, C. L.

    2016-03-01

    Watershed and global-scale nitrogen (N) budgets indicate that the majority of the N surplus in anthropogenic landscapes does not reach the coastal oceans. While there is general consensus that this ‘missing’ N either exits the landscape via denitrification or is retained within watersheds as nitrate or organic N, the relative magnitudes of these pools and fluxes are subject to considerable uncertainty. Our study, for the first time, provides direct, large-scale evidence of N accumulation in the root zones of agricultural soils that may account for much of the ‘missing N’ identified in mass balance studies. We analyzed long-term soil data (1957-2010) from 2069 sites throughout the Mississippi River Basin (MRB) to reveal N accumulation in cropland of 25-70 kg ha-1 yr-1, a total of 3.8 ± 1.8 Mt yr-1 at the watershed scale. We then developed a simple modeling framework to capture N depletion and accumulation dynamics under intensive agriculture. Using the model, we show that the observed accumulation of soil organic N (SON) in the MRB over a 30 year period (142 Tg N) would lead to a biogeochemical lag time of 35 years for 99% of legacy SON, even with complete cessation of fertilizer application. By demonstrating that agricultural soils can act as a net N sink, the present work makes a critical contribution towards the closing of watershed N budgets.

  6. Target Selection Signals Influence Perceptual Decisions by Modulating the Onset and Rate of Evidence Accumulation.

    PubMed

    Loughnane, Gerard M; Newman, Daniel P; Bellgrove, Mark A; Lalor, Edmund C; Kelly, Simon P; O'Connell, Redmond G

    2016-02-22

    Computational and neurophysiological research has highlighted neural processes that accumulate sensory evidence for perceptual decisions [1]. These processes have been studied in the context of highly simplified perceptual discrimination paradigms in which the physical evidence appears at times and locations that are either entirely predictable or exogenously cued (e.g., by the onset of the stimulus itself). Yet, we are rarely afforded such certainty in everyday life. For example, when driving along a busy motorway, we must continually monitor the movements of surrounding vehicles for events that call for a lane change. In such scenarios, it is unknown which of the continuously present information sources will become relevant or when. Although it is well established that evidence integration provides an effective mechanism for countering the impact of noise [2], the question of how this mechanism is implemented in the face of uncertain evidence onsets has yet to be answered. Here, we show that when monitoring two potential sources of information for evidence occurring unpredictably in both time and space, the human brain employs discrete, early target selection signals that significantly modulate the onset and rate of neural evidence accumulation, and thereby the timing and accuracy of perceptual reports. These selection signals share many of the key characteristics of the N2pc component highlighted in the literature on visual search [3, 4] yet are present even in the absence of distractors and under situations of low temporal and spatial uncertainty. These data provide novel insights into how target selection supports decision making in uncertain environments. PMID:26853360

  7. Experimental studies of MOS inversion and accumulation layers: Quantum mechanical effects and mobility

    NASA Astrophysics Data System (ADS)

    Chindalore, Gowrishankar L.

    The development of fast, multi-functional, and energy efficient integrated circuits, is made possible by aggressively scaling the gate lengths of the MOS devices into the sub-quarter micron regime. However, with the increasing cost of fabrication, there is a strong need for the development of reliable and accurate device simulation capabilities. The development of the theoretical models for simulators is guided by extensive experimental data, which enable an experimental verification of the models, and lead to a better understanding of the underlying physics. This dissertation presents the methodology and the results for one such experimental effort, where two important physical effects in the inversion layer and the accumulation layer of a MOS device, namely, the quantum mechanical (QM) effects and the carrier mobility are investigated. Accordingly, this dissertation has been divided into two parts, with the first part discussing the increase in the threshold voltage and the accumulation electrical oxide thickness due to QM effects. The second part discusses the methodology and the experimental results for the extraction of the majority carrier mobilities in the accumulation layers of a MOSFET. The continued scaling of the MOS gate length requires decreased gate oxide thickness (tox) and increased channel doping (NB) in order to improve device performance while suppressing the short- channel effects. The combination of the two result in large enough transverse electric fields to cause significant quantization of the carriers in the potential well at the Si/SiO2 interface. Hence, compared to the classical calculations (where the QM effects are ignored), the QM effects are found to lead to an increase in the experimental threshold voltage by approximately 100mV, and an overestimation of the physical oxide thickness by approximately 3-4A, in MOSFET devices with a gate oxide thickness and the doping level anticipated for technologies with sub-quarter micron gate

  8. Accumulation of intimal platelets in cerebral arteries following experimental subarachnoid hemorrhage in cats

    SciTech Connect

    Haining, J.L.; Clower, B.R.; Honma, Y.; Smith, R.R.

    1988-07-01

    From 2 hours to 23 days following experimental subarachnoid hemorrhage, the accumulation of indium-111-labeled platelets on the intimal surface of the middle cerebral artery was studied in 23 cats. Subarachnoid hemorrhage was produced by transorbital rupture of the right middle cerebral artery. Of the 23 cats, 17 exhibited right middle cerebral artery/left middle cerebral artery radioactivity ratios of greater than 1.25. When these results were compared with those of 12 control cats, 0.001 less than p less than 0.005 (chi2 test). Thus, the results from the control and experimental groups are significantly different and indicate early (after 2 hours) preferential accumulation of intimal platelets in the ruptured right middle cerebral artery compared with the unruptured left middle cerebral artery and new platelet deposition continuing for up to 23 days. However, the experimental group did not reveal a clear pattern for platelet accumulation following subarachnoid hemorrhage. There was no simple correlation between the magnitude of the radioactivity ratios and the time after hemorrhage when the cats were killed although the ratios for 2 hours to 7 days seemed greater than those for 8 to 23 days. Assuming the pivotal role of platelets in the angiopathy of subarachnoid hemorrhage, the administration of antiplatelet agents as soon as possible following its occurrence may be of value.

  9. 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

  10. 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…

  11. Evidence Accumulation in Obsessive-Compulsive Disorder: the Role of Uncertainty and Monetary Reward on Perceptual Decision-Making Thresholds

    PubMed Central

    Banca, Paula; Vestergaard, Martin D; Rankov, Vladan; Baek, Kwangyeol; Mitchell, Simon; Lapa, Tatyana; Castelo-Branco, Miguel; Voon, Valerie

    2015-01-01

    The compulsive behaviour underlying obsessive-compulsive disorder (OCD) may be related to abnormalities in decision-making. The inability to commit to ultimate decisions, for example, patients unable to decide whether their hands are sufficiently clean, may reflect failures in accumulating sufficient evidence before a decision. Here we investigate the process of evidence accumulation in OCD in perceptual discrimination, hypothesizing enhanced evidence accumulation relative to healthy volunteers. Twenty-eight OCD patients and thirty-five controls were tested with a low-level visual perceptual task (random-dot-motion task, RDMT) and two response conflict control tasks. Regression analysis across different motion coherence levels and Hierarchical Drift Diffusion Modelling (HDDM) were used to characterize response strategies between groups in the RDMT. Patients required more evidence under high uncertainty perceptual contexts, as indexed by longer response time and higher decision boundaries. HDDM, which defines a decision when accumulated noisy evidence reaches a decision boundary, further showed slower drift rate towards the decision boundary reflecting poorer quality of evidence entering the decision process in patients under low uncertainty. With monetary incentives emphasizing speed and penalty for slower responses, patients decreased the decision thresholds relative to controls, accumulating less evidence in low uncertainty. These findings were unrelated to visual perceptual deficits and response conflict. This study provides evidence for impaired decision-formation processes in OCD, with a differential influence of high and low uncertainty contexts on evidence accumulation (decision threshold) and on the quality of evidence gathered (drift rates). It further emphasizes that OCD patients are sensitive to monetary incentives heightening speed in the speed-accuracy tradeoff, improving evidence accumulation. PMID:25425323

  12. Evidence accumulation in obsessive-compulsive disorder: the role of uncertainty and monetary reward on perceptual decision-making thresholds.

    PubMed

    Banca, Paula; Vestergaard, Martin D; Rankov, Vladan; Baek, Kwangyeol; Mitchell, Simon; Lapa, Tatyana; Castelo-Branco, Miguel; Voon, Valerie

    2015-04-01

    The compulsive behaviour underlying obsessive-compulsive disorder (OCD) may be related to abnormalities in decision-making. The inability to commit to ultimate decisions, for example, patients unable to decide whether their hands are sufficiently clean, may reflect failures in accumulating sufficient evidence before a decision. Here we investigate the process of evidence accumulation in OCD in perceptual discrimination, hypothesizing enhanced evidence accumulation relative to healthy volunteers. Twenty-eight OCD patients and thirty-five controls were tested with a low-level visual perceptual task (random-dot-motion task, RDMT) and two response conflict control tasks. Regression analysis across different motion coherence levels and Hierarchical Drift Diffusion Modelling (HDDM) were used to characterize response strategies between groups in the RDMT. Patients required more evidence under high uncertainty perceptual contexts, as indexed by longer response time and higher decision boundaries. HDDM, which defines a decision when accumulated noisy evidence reaches a decision boundary, further showed slower drift rate towards the decision boundary reflecting poorer quality of evidence entering the decision process in patients under low uncertainty. With monetary incentives emphasizing speed and penalty for slower responses, patients decreased the decision thresholds relative to controls, accumulating less evidence in low uncertainty. These findings were unrelated to visual perceptual deficits and response conflict. This study provides evidence for impaired decision-formation processes in OCD, with a differential influence of high and low uncertainty contexts on evidence accumulation (decision threshold) and on the quality of evidence gathered (drift rates). It further emphasizes that OCD patients are sensitive to monetary incentives heightening speed in the speed-accuracy tradeoff, improving evidence accumulation. PMID:25425323

  13. Origin of Aphyric Phonolitic Magmas: Natural Evidences and Experimental Constraints

    NASA Astrophysics Data System (ADS)

    Masotta, M.; Freda, C.; Gaeta, M.

    2010-12-01

    Large explosive phonolitic eruptions are commonly characterised by aphyric juvenile eruptive products. Taking into account the low density contrast among phonolitic composition and settling phases (i.e., feldspar and leucite), the almost complete lack of crystals in these differentiated compositions rises the question of which process could produce such an efficient crystal-melt separation. Seeking for an answer, we have investigated crystallization in presence of a thermal gradient as a possible mechanism for crystal-melt separation, considering both chemical and physical effects acting on a variably crystallized system. Using a natural tephri-phonolitic composition as starting material (M.te Aguzzo scoria cone, Sabatini Volcanic District, Central Italy), we have reproduced thermal gradient-driven crystallization in order to simulate the crystallization process in a thermally zoned magma chamber. Crystallization degree (paragenesis made of clinopyroxene±feldspars±leucite) as well as melt composition varies along the thermal gradient. In particular, melt composition ranges from the tephri-phonolitic starting composition at the bottom of the charge (hottest and aphyric zone) to phonolitic at the top (cooler and heterogeneously-crystallised zone). Backscattered images of experimental products clearly evidence: i) the aphyric tephri-phonolitic melt region at the bottom of the charge; ii) a drop-shaped crystal clustering in the middle zone; and iii) large aphyric belt and pockets (up to 100 µm wide) of phonolitic melt, with large deformed-shaped sanidine occurring at their margin, at the charge top region. The latter two features, resulting from solid-melt displacements, suggest that the segregation of phonolitic melt can be related to crystal sinking and compaction. On the other hand, the compositional variability of the melt along the thermal gradient is directly related to the crystallization degree, indicating that chemical diffusion and thermal migration have

  14. Distinct effects of prefrontal and parietal cortex inactivations on an accumulation of evidence task in the rat

    PubMed Central

    Erlich, Jeffrey C; Brunton, Bingni W; Duan, Chunyu A; Hanks, Timothy D; Brody, Carlos D

    2015-01-01

    Numerous brain regions have been shown to have neural correlates of gradually accumulating evidence for decision-making, but the causal roles of these regions in decisions driven by accumulation of evidence have yet to be determined. Here, in rats performing an auditory evidence accumulation task, we inactivated the frontal orienting fields (FOF) and posterior parietal cortex (PPC), two rat cortical regions that have neural correlates of accumulating evidence and that have been proposed as central to decision-making. We used a detailed model of the decision process to analyze the effect of inactivations. Inactivation of the FOF induced substantial performance impairments that were quantitatively best described as an impairment in the output pathway of an evidence accumulator with a long integration time constant (>240 ms). In contrast, we found a minimal role for PPC in decisions guided by accumulating auditory evidence, even while finding a strong role for PPC in internally-guided decisions. DOI: http://dx.doi.org/10.7554/eLife.05457.001 PMID:25869470

  15. 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.

  16. Rapid temporal accumulation in spider fear: Evidence from hierarchical drift diffusion modelling.

    PubMed

    Tipples, Jason

    2015-12-01

    Fear can distort sense of time--making time seem slow or even stand still. Here, I used hierarchical drift diffusion modeling (HDDM; Vandekerckhove, Tuerlinckx, & Lee, 2008, 2011; Wiecki, Sofer, & Frank, 2013) to test the idea that temporal accumulation speeds up during fear. Eighteen high fearful and 23 low fearful participants judged the duration of both feared stimuli (spiders) and nonfeared stimuli (birds) in a temporal bisection task. The drift diffusion modeling results support the main hypothesis. In high but not low fearful individuals, evidence accumulated more rapidly toward a long duration decision-drift rates were higher-for spiders compared with birds. This result and further insights into how fear affects time perception would not have been possible on the basis of analyses of choice proportion data alone. Further results were interpreted in the context of a recent 2-stage model of time perception (Balcı & Simen, 2014). The results highlight the usefulness of diffusion modeling to test process-based explanations of disordered cognition in emotional disorders. PMID:25938616

  17. Rotational grazing on rangelands: Reconciliation of perception and experimental evidence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In spite of overwhelming experimental evidence to the contrary, rotational grazing continues to be promoted and implemented as the only viable grazing strategy. The goals of this synthesis are to 1) reevaluate the complexity, underlying assumptions, and ecological processes of grazed ecosystems, 2) ...

  18. 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…

  19. 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. PMID:26012708

  20. Experimental Plan for Crystal Accumulation Studies in the WTP Melter Riser

    SciTech Connect

    Miller, D.; Fowley, M.

    2015-04-28

    This experimental plan defines crystal settling experiments to be in support of the U.S. Department of Energy – Office of River Protection crystal tolerant glass program. The road map for development of crystal-tolerant high level waste glasses recommends that fluid dynamic modeling be used to better understand the accumulation of crystals in the melter riser and mechanisms of removal. A full-scale version of the Hanford Waste Treatment and Immobilization Plant (WTP) melter riser constructed with transparent material will be used to provide data in support of model development. The system will also provide a platform to demonstrate mitigation or recovery strategies in off-normal events where crystal accumulation impedes melter operation. Test conditions and material properties will be chosen to provide results over a variety of parameters, which can be used to guide validation experiments with the Research Scale Melter at the Pacific Northwest National Laboratory, and that will ultimately lead to the development of a process control strategy for the full scale WTP melter. The experiments described in this plan are divided into two phases. Bench scale tests will be used in Phase 1 (using the appropriate solid and fluid simulants to represent molten glass and spinel crystals) to verify the detection methods and analytical measurements prior to their use in a larger scale system. In Phase 2, a full scale, room temperature mockup of the WTP melter riser will be fabricated. The mockup will provide dynamic measurements of flow conditions, including resistance to pouring, as well as allow visual observation of crystal accumulation behavior.

  1. Accumulation and Toxicity of Superparamagnetic Iron Oxide Nanoparticles in Cells and Experimental Animals

    PubMed Central

    Jarockyte, Greta; Daugelaite, Egle; Stasys, Marius; Statkute, Urte; Poderys, Vilius; Tseng, Ting-Chen; Hsu, Shan-Hui; Karabanovas, Vitalijus; Rotomskis, Ricardas

    2016-01-01

    The uptake and distribution of negatively charged superparamagnetic iron oxide (Fe3O4) nanoparticles (SPIONs) in mouse embryonic fibroblasts NIH3T3, and magnetic resonance imaging (MRI) signal influenced by SPIONs injected into experimental animals, were visualized and investigated. Cellular uptake and distribution of the SPIONs in NIH3T3 after staining with Prussian Blue were investigated by a bright-field microscope equipped with digital color camera. SPIONs were localized in vesicles, mostly placed near the nucleus. Toxicity of SPION nanoparticles tested with cell viability assay (XTT) was estimated. The viability of NIH3T3 cells remains approximately 95% within 3–24 h of incubation, and only a slight decrease of viability was observed after 48 h of incubation. MRI studies on Wistar rats using a clinical 1.5 T MRI scanner were showing that SPIONs give a negative contrast in the MRI. The dynamic MRI measurements of the SPION clearance from the injection site shows that SPIONs slowly disappear from injection sites and only a low concentration of nanoparticles was completely eliminated within three weeks. No functionalized SPIONs accumulate in cells by endocytic mechanism, none accumulate in the nucleus, and none are toxic at a desirable concentration. Therefore, they could be used as a dual imaging agent: as contrast agents for MRI and for traditional optical biopsy by using Prussian Blue staining. PMID:27548152

  2. Accumulation and Toxicity of Superparamagnetic Iron Oxide Nanoparticles in Cells and Experimental Animals.

    PubMed

    Jarockyte, Greta; Daugelaite, Egle; Stasys, Marius; Statkute, Urte; Poderys, Vilius; Tseng, Ting-Chen; Hsu, Shan-Hui; Karabanovas, Vitalijus; Rotomskis, Ricardas

    2016-01-01

    The uptake and distribution of negatively charged superparamagnetic iron oxide (Fe₃O₄) nanoparticles (SPIONs) in mouse embryonic fibroblasts NIH3T3, and magnetic resonance imaging (MRI) signal influenced by SPIONs injected into experimental animals, were visualized and investigated. Cellular uptake and distribution of the SPIONs in NIH3T3 after staining with Prussian Blue were investigated by a bright-field microscope equipped with digital color camera. SPIONs were localized in vesicles, mostly placed near the nucleus. Toxicity of SPION nanoparticles tested with cell viability assay (XTT) was estimated. The viability of NIH3T3 cells remains approximately 95% within 3-24 h of incubation, and only a slight decrease of viability was observed after 48 h of incubation. MRI studies on Wistar rats using a clinical 1.5 T MRI scanner were showing that SPIONs give a negative contrast in the MRI. The dynamic MRI measurements of the SPION clearance from the injection site shows that SPIONs slowly disappear from injection sites and only a low concentration of nanoparticles was completely eliminated within three weeks. No functionalized SPIONs accumulate in cells by endocytic mechanism, none accumulate in the nucleus, and none are toxic at a desirable concentration. Therefore, they could be used as a dual imaging agent: as contrast agents for MRI and for traditional optical biopsy by using Prussian Blue staining. PMID:27548152

  3. Evidence for gas accumulation associated with diapirism and gas hydrates at the head of the Cape Fear Slide

    NASA Astrophysics Data System (ADS)

    Schmuck, E. A.; Paull, C. K.

    1993-09-01

    Single-channel seismic reflection profiles show evidence for areas of significant gas accumulation at the head of the Cape Fear Slide on the continental rise off North Carolina. Gas accumulation appears to occur beneath a gas hydrate seal in landward-dipping strata and in domed strata associated with diapirism. In addition, gas venting may have occurred near diapirs located at the head of the slide.

  4. Evidence for gas accumulation associated with diapirism and gas hydrates at the head of the Cape Fear Slide

    USGS Publications Warehouse

    Schmuck, E.A.; Paull, C.K.

    1993-01-01

    Single-channel seismic reflection profiles show evidence for areas of significant gas accumulation at the head of the Cape Fear Slide on the continental rise off North Carolina. Gas accumulation appears to occur beneath a gas hydrate seal in landward-dipping strata and in domed strata associated with diapirism. In addition, gas venting may have occurred near diapirs located at the head of the slide. ?? 1993 Springer-Verlag.

  5. Experimental evidence of replica symmetry breaking in random lasers

    NASA Astrophysics Data System (ADS)

    Ghofraniha, N.; Viola, I.; di Maria, F.; Barbarella, G.; Gigli, G.; Leuzzi, L.; Conti, C.

    2015-01-01

    Spin-glass theory is one of the leading paradigms of complex physics and describes condensed matter, neural networks and biological systems, ultracold atoms, random photonics and many other research fields. According to this theory, identical systems under identical conditions may reach different states. This effect is known as replica symmetry breaking and is revealed by the shape of the probability distribution function of an order parameter named the Parisi overlap. However, a direct experimental evidence in any field of research is still missing. Here we investigate pulse-to-pulse fluctuations in random lasers, we introduce and measure the analogue of the Parisi overlap in independent experimental realizations of the same disordered sample, and we find that the distribution function yields evidence of a transition to a glassy light phase compatible with a replica symmetry breaking.

  6. Silica uptake by Spartina—evidence of multiple modes of accumulation from salt marshes around the world

    PubMed Central

    Carey, Joanna C.; Fulweiler, Robinson W.

    2014-01-01

    Silicon (Si) plays a critical role in plant functional ecology, protecting plants from multiple environmental stressors. While all terrestrial plants contain some Si, wetland grasses are frequently found to have the highest concentrations, although the mechanisms driving Si accumulation in wetland grasses remain in large part uncertain. For example, active Si accumulation is often assumed to be responsible for elevated Si concentrations found in wetland grasses. However, life stage and differences in Si availability in the surrounding environment also appear to be important variables controlling the Si concentrations of wetland grasses. Here we used original data from five North American salt marshes, as well as all known published literature values, to examine the primary drivers of Si accumulation in Spartina, a genus of prolific salt marsh grasses found worldwide. We found evidence of multiple modes of Si accumulation in Spartina, with passive accumulation observed in non-degraded marshes where Spartina was native, while rejective accumulation was found in regions where Spartina was invasive. Evidence of active accumulation was found in only one marsh where Spartina was native, but was also subjected to nutrient over-enrichment. We developed a conceptual model which hypothesizes that the mode of Si uptake by Spartina is dependent on local environmental factors and genetic origin, supporting the idea that plant species should be placed along a spectrum of Si accumulation. We hypothesize that Spartina exhibits previously unrecognized phenotypic plasticity with regard to Si accumulation, allowing these plants to respond to changes in marsh condition. These results provide new insight regarding how salt marsh ecosystems regulate Si exchange at the land-sea interface. PMID:24904599

  7. Experimental measurement and modeling of snow accumulation and snowmelt in a mountain microcatchment

    NASA Astrophysics Data System (ADS)

    Danko, Michal; Krajčí, Pavel; Hlavčo, Jozef; Kostka, Zdeněk; Holko, Ladislav

    2016-04-01

    Fieldwork is a very useful source of data in all geosciences. This naturally applies also to the snow hydrology. Snow accumulation and snowmelt are spatially very heterogeneous especially in non-forested, mountain environments. Direct field measurements provide the most accurate information about it. Quantification and understanding of processes, that cause these spatial differences are crucial in prediction and modelling of runoff volumes in spring snowmelt period. This study presents possibilities of detailed measurement and modeling of snow cover characteristics in a mountain experimental microcatchment located in northern part of Slovakia in Western Tatra mountains. Catchment area is 0.059 km2 and mean altitude is 1500 m a.s.l. Measurement network consists of 27 snow poles, 3 small snow lysimeters, discharge measurement device and standard automatic weather station. Snow depth and snow water equivalent (SWE) were measured twice a month near the snow poles. These measurements were used to estimate spatial differences in accumulation of SWE. Snowmelt outflow was measured by small snow lysimeters. Measurements were performed in winter 2014/2015. Snow water equivalent variability was very high in such a small area. Differences between particular measuring points reached 600 mm in time of maximum SWE. The results indicated good performance of a snow lysimeter in case of snowmelt timing identification. Increase of snowmelt measured by the snow lysimeter had the same timing as increase in discharge at catchment's outlet and the same timing as the increase in air temperature above the freezing point. Measured data were afterwards used in distributed rainfall-runoff model MIKE-SHE. Several methods were used for spatial distribution of precipitation and snow water equivalent. The model was able to simulate snow water equivalent and snowmelt timing in daily step reasonably well. Simulated discharges were slightly overestimated in later spring.

  8. Experimental evidence of hyperbolic heat conduction in processed meat

    SciTech Connect

    Mitra, K.; Kumar, S.; Vedavarz, A.; Moallemi, M.K.

    1995-08-01

    The objective of this paper is to present experimental evidence of the wave nature of heat propagation in processed meat and to demonstrate that the hyperbolic heat conduction model is an accurate representation, on a macroscopic level, of the heat conduction process in such biological material. The value of the characteristic thermal time of a specific material, processed bologna meat, is determined experimentally. As a part of the work different thermophysical properties are also measured. The measured temperature distributions in the samples are compared with the Fourier results and significant deviation between the two is observed, especially during the initial stages of the transient conduction process. The measured values are found to match the theoretical non-Fourier hyperbolic predictions very well. The superposition of waves occurring inside the meat sample due to the hyperbolic nature of heat conduction is also proved experimentally. 14 refs., 7 figs., 2 tabs.

  9. Global warming: Experimental study about the effect of accumulation of greenhouse gases in the atmosphere

    NASA Astrophysics Data System (ADS)

    Molto, Carlos; Mas, Miquel

    2010-05-01

    The project presented here was developed by fifteen year old students of the Institut Sabadell (Sabadell Secondary School. Spain). The objective of this project was to raise the students awareness' about the problem of climate change, mainly caused by the accumulation of greenhouse gases in the atmosphere. It is also intended that students use the scientific method as an effective system of troubleshooting and that they use the ICTs (Information and Communication Technologies) to elicit data and process information. To develop this project, four lessons of sixty minutes each were needed. The first lesson sets out the role of the atmosphere as an Earth's temperature regulator, highlighting the importance of keeping the levels of carbon dioxide, methane and water steam in balance. The second lesson is focused on the experimental activity that students will develop in the following lesson. In lesson two, students will present and justify their hypothesis about the experiment. Some theoretical concepts, necessary to carry out the experiment, will also be explained. The third lesson involves the core of the project, that is the experiment in the laboratory. The experiment consists on performing the atmosphere heating on a little scale. Four different atmospheres are created inside four plastic boxes heated by an infrared lamp. Students work in groups (one group for each atmosphere) and have to monitor the evolution of temperature by means of a temperature sensor (Multilog software). The first group has to observe the relationship between temperature and carbon dioxide levels increase, mainly caused by the widespread practice of burning fossil fuels by growing human populations. The task of this group is to measure simultaneously the temperature of an empty box (without CO2) and the temperature of a box with high carbon dioxide concentration. The carbon dioxide concentration is the result of the chemical reaction when sodium carbonate mixes with hydrochloric acid. The

  10. 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

  11. The tripole vortex: Experimental evidence and explicit solutions.

    PubMed

    Kizner, Ziv; Khvoles, Ruvim

    2004-01-01

    Based on experimental evidence, explicit vorticity-distributed solutions to the Euler equations in two dimensions are constructed describing the tripole vortex. The vortex form and the solution outside the region of nonzero vorticity are derived analytically, while the interior is solved numerically. The continuous-vorticity solution reproduces the main features of the tripoles observed in laboratory experiments and numerical simulations-their shape, flow pattern, and the form of the nonlinear vorticity vs streamfunction relation. The approach followed in the construction of a tripole proves to be beneficial in the search for higher-order multipoles, an example being a smooth quadrupole solution. PMID:15324169

  12. Sleep Duration and Cardiovascular Disease Risk: Epidemiologic and Experimental Evidence.

    PubMed

    Covassin, Naima; Singh, Prachi

    2016-03-01

    Inadequate sleep is increasingly pervasive, and the impact on health remains to be fully understood. The cardiovascular consequences alone appear to be substantial. This review summarizes epidemiologic evidence regarding the association between extremes of sleep duration and the prevalence and incidence of cardiovascular diseases. The adverse effects of experimental sleep loss on physiological functions are discussed, along with cardiovascular risk factors that may underlie the association with increased morbidity and mortality. Current data support the concept that inadequate sleep duration confers heightened cardiovascular risk. Thus implementation of preventative strategies may reduce the potential disease burden associated with this high-risk behavior. PMID:26972035

  13. Experimental Evidence for Dark Excitons in Monolayer WSe_{2}.

    PubMed

    Zhang, Xiao-Xiao; You, Yumeng; Zhao, Shu Yang Frank; Heinz, Tony F

    2015-12-18

    Transition metal dichalcogenides in the class MX_{2} (M=Mo, W; X=S, Se) have been identified as direct-gap semiconductors in the monolayer limit. Here, we examine light emission of monolayer WSe_{2} using temperature-dependent photoluminescence and time-resolved photoluminescence spectroscopy. We present experimental evidence for the existence of an optically forbidden dark state of the band-gap exciton that lies tens of meV below the optically bright state. The presence of the dark state is manifest in the strong quenching of light emission observed at reduced temperatures. The experimental findings are consistent with theoretical predictions of spin-polarized conduction and valence bands at the K point of the Brillouin zone, with the minimum gap occurring between bands of opposite electron spin. PMID:26722944

  14. Copper and cobalt mobility in soil and accumulation in a metallophyte as influenced by experimental manipulation of soil chemical factors.

    PubMed

    Lange, Bastien; Pourret, Olivier; Meerts, Pierre; Jitaru, Petru; Cancès, Benjamin; Grison, Claude; Faucon, Michel-Pierre

    2016-03-01

    The influence of Fe oxides, Mn oxides and organic matter (OM) on the Cu and Co mobility in soil and accumulation in the metallophyte Anisopappus chinensis (Ac), as compared with Helianthus annuus (Ha), was experimentally investigated. Growth and accumulation response when increasing the exchangeable Cu and Co concentrations in soil were also investigated. Plants were cultivated on soil where concentrations of Cu, Co, Fe oxides, Mn oxides and OM content were varied according to 36 treatments. The OM supply decreased the Cu mobility and increased the Co mobility, resulting in decreasing the foliar Cu of Ac and increasing the foliar Co of Ha. The Fe oxides supply could increase the Cu accumulation for Ac, but was not verified for Ha. Compared with Ha, Ac increasingly accumulated Cu and Co without negative effect on plant growth while increasing Cu and Co mobility to phytotoxic concentrations. The results revealed promising perspectives for the use of Ac in Cu-contaminated environment phytoremediation applications. PMID:26706934

  15. Ice core evidence for a recent increase in snow accumulation in coastal Dronning Maud Land, Antarctica

    NASA Astrophysics Data System (ADS)

    Philippe, Morgane; Tison, Jean-Louis; Fjøsne, Karen; Hubbard, Bryn; Kjær, Helle Astrid; Lenaerts, Jan; Sheldon, Simon Geoffrey; De Bondt, Kevin; Claeys, Philippe; Pattyn, Frank

    2016-04-01

    Ice cores provide temporal records of snow accumulation, a crucial component of Antarctic mass balance. Coastal areas are particularly under-represented in such records, despite their relatively high and sensitive accumulation rates. Here we present records from a 120 m ice core drilled on Derwael Ice Rise, coastal Dronning Maud Land (DML), East Antarctica in 2012. We date the ice core bottom back to 1745 ± 2 AD. δ18O and δD stratigraphy is supplemented by discontinuous major ion profiles, and verified independently by electrical conductivity measurements (ECM) to detect volcanic horizons. The resulting annual layer history is combined with the core density profile to calculate accumulation history, corrected for the influence of ice deformation. The mean long-term accumulation is 0.425 ± 0.035 m water equivalent (w.e.) a‑1 (average corrected value). Reconstructed annual accumulation rates show an increase from 1955 onward to a mean value of 0.61 ± 0.02 m w.e. a‑1 between 1955 and 2012. This trend is compared to other reported accumulation data in Antarctica, generally showing a high spatial variability. Applying the Community Earth System Model demonstrated that sea ice and atmosphere patterns largely explain the accumulation variability. This is the first and longest record from a coastal ice core in East Antarctica showing a steady increase during the 20th and 21st centuries, thereby confirming modelling predictions.

  16. Dichlorvos carcinogenicity: an assessment of the weight of experimental evidence.

    PubMed

    Mennear, J H

    1994-12-01

    After 30 years of experience with human exposure to dichlorvos (DDVP) in the home, workplace, and sickroom, the U.S. EPA has published its intent to revoke the food additive registration of this cholinesterase-inhibiting insecticide. The basis for the Agency action is the result of the National Toxicology Program (NTP) toxicology and carcinogenesis study of DDVP in rats and mice (NTP Technical Report No. 342, September 1989). In those experiments the NTP considered the result in the female mouse portion of the study to afford unequivocal evidence of carcinogenicity. The NTP considered the interpretations of the male and female rat and the male mouse studies to be less than clear. Despite the NTP interpretation, the EPA considers the male rat data (increased incidence of mononuclear cell leukemia) to be sufficient to warrant the regulatory change. The purpose of this report is to summarize a review of the interpretation of the NTP data and to assess the predictive validity of the results relative to potential human health impact. Critical review of experimental data indicates that the evidence for a carcinogenic effect of DDVP in animals is equivocal. Further, DDVP possess no in vivo mutagenic activity in mammalian assay systems and it bears no significant structural similarity to known carcinogens. Therefore, a weight-of-the-evidence analysis leads to the conclusion that DDVP poses neither mutagenic nor carcinogenic risks to humans exposed under normal conditions of use of foreseeable conditions of misuse. PMID:7724838

  17. Experimental evidence for compositional syntax in bird calls.

    PubMed

    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

  18. 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

  19. Experimental evidence of the double-porosity effects in geomaterials

    NASA Astrophysics Data System (ADS)

    Tran Ngoc, Tien; Lewandowska, Jolanta; Bertin, Henri

    2014-06-01

    Double-porosity is an important characteristic of microstructure in a large range of geomaterials. It designs porous media with connected fissures/fractures or aggregated soils. The origin of double-porosity can be natural or/and it can result from mechanical, chemical or biological damage. The presence of double-porosity can significantly affect the behaviour of geomaterials. In this paper we provide an experimental evidence of the double-porosity effects by performing laboratory experiments. Series of tracer dispersion experiments (in saturated and unsaturated steady-state water flow conditions) in a physical model of double-porosity geomaterial were carried out. For the comparative purposes, experiments of the same type were also performed in a singleporosity model medium. The results clearly showed that the double-porosity microstructure leads to the non-Fickian behaviour of the tracer (early breakthrough and long tail) in both saturated and unsaturated cases.

  20. Mechanisms of T-lymphocyte accumulation during experimental pleural infection induced by Mycobacterium bovis BCG.

    PubMed

    Souza, Mariana C; Penido, Carmen; Costa, Maria F S; Henriques, Maria Graças

    2008-12-01

    Tuberculous pleurisy is a frequent extrapulmonary manifestation characterized by accumulation of fluid and inflammatory cells in the pleural space. Here, we investigated the mechanisms of T-lymphocyte accumulation in the pleural space by using a murine model of pleurisy induced by Mycobacterium bovis BCG. Intrathoracic (i.t.) injection of BCG (4.5 x 10(5) bacteria/cavity) induced accumulation of T lymphocytes in the pleural cavities of C57BL/6 mice. We observed the presence of CFU in pleural washes conducted 1, 2, 3, 7, and 15 days after pleurisy induction. Pretreatment with fucoidan inhibited T-lymphocyte accumulation at 1 day, but not at 15 days, after BCG-induced pleurisy. Accordingly, adoptive transfer of fluorescein isothiocyanate-labeled blood mononuclear cells to infected mice showed that T lymphocytes migrated into the pleural cavity 1 day (but not 15 days) after BCG injection. Cell-free pleural wash fluids recovered from mice 1 day after BCG i.t. stimulation (day 1 BCG-PW), but not day 7 or day 15 BCG-PW, induced in vitro T-cell transmigration, which was dependent on L-, P-, and E-selectins. In contrast, day 7 BCG-PW (but not day 1 BCG-PW) induced in vitro T-lymphocyte proliferation via interleukin-2 (IL-2) and gamma interferon (IFN-gamma). Accordingly, in vivo IL-2 or IFN-gamma neutralization abolished T-lymphocyte accumulation 7 days after pleurisy induction. Our results demonstrate that pleural infection induced by BCG leads to T-lymphocyte accumulation in two waves. The acute phase depends on selectin-mediated migration, while the second wave of T-lymphocyte accumulation seems to depend on a local proliferation induced by cytokines produced in situ. PMID:18809659

  1. Female Rose Bitterling Prefer MHC-Dissimilar Males: Experimental Evidence

    PubMed Central

    Reichard, Martin; Spence, Rowena; Bryjová, Anna; Bryja, Josef; Smith, Carl

    2012-01-01

    The role of genetic benefits in female mate choice remains a controversial aspect of sexual selection theory. In contrast to “good allele” models of sexual selection, “compatible allele” models of mate choice predict that females prefer mates with alleles complementary to their own rather than conferring additive effects. While correlative results suggest complementary genetic effects to be plausible, direct experimental evidence is scarce. A previous study on the Chinese rose bitterling (Rhodeus ocellatus) demonstrated a positive correlation between female mate choice, offspring growth and survival, and the functional dissimilarity between the Major Histocompatibility Complex (MHC) alleles of males and females. Here we directly tested whether females used cues associated with MHC genes to select genetically compatible males in an experimental framework. By sequentially pairing females with MHC similar and dissimilar males, based on a priori known MHC profiles, we showed that females discriminated between similar and dissimilar males and deposited significantly more eggs with MHC dissimilar males. Notably, the degree of dissimilarity was an important factor for female decision to mate, possibly indicating a potential threshold value of dissimilarity for decision making, or of an indirect effect of the MHC. PMID:22815816

  2. 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. PMID:27259749

  3. 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. PMID:22875725

  4. 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.

  5. Temporal assessment of nanoparticle accumulation after experimental brain injury: Effect of particle size

    PubMed Central

    Bharadwaj, Vimala N.; Lifshitz, Jonathan; Adelson, P. David; Kodibagkar, Vikram D.; Stabenfeldt, Sarah E.

    2016-01-01

    Nanoparticle (NP) based therapeutic and theranostic agents have been developed for various diseases, yet application to neural disease/injury is restricted by the blood-brain-barrier (BBB). Traumatic brain injury (TBI) results in a host of pathological alterations, including transient breakdown of the BBB, thus opening a window for NP delivery to the injured brain tissue. This study focused on investigating the spatiotemporal accumulation of different sized NPs after TBI. Specifically, animal cohorts sustaining a controlled cortical impact injury received an intravenous injection of PEGylated NP cocktail (20, 40, 100, and 500 nm, each with a unique fluorophore) immediately (0 h), 2 h, 5 h, 12 h, or 23 h after injury. NPs were allowed to circulate for 1 h before perfusion and brain harvest. Confocal microscopy demonstrated peak NP accumulation within the injury penumbra 1 h post-injury. An inverse relationship was found between NP size and their continued accumulation within the penumbra. NP accumulation preferentially occurred in the primary motor and somatosensory areas of the injury penumbra as compared to the parietal association and visual area. Thus, we characterized the accumulation of particles up to 500 nm at different times acutely after injury, indicating the potential of NP-based TBI theranostics in the acute period after injury. PMID:27444615

  6. Temporal assessment of nanoparticle accumulation after experimental brain injury: Effect of particle size.

    PubMed

    Bharadwaj, Vimala N; Lifshitz, Jonathan; Adelson, P David; Kodibagkar, Vikram D; Stabenfeldt, Sarah E

    2016-01-01

    Nanoparticle (NP) based therapeutic and theranostic agents have been developed for various diseases, yet application to neural disease/injury is restricted by the blood-brain-barrier (BBB). Traumatic brain injury (TBI) results in a host of pathological alterations, including transient breakdown of the BBB, thus opening a window for NP delivery to the injured brain tissue. This study focused on investigating the spatiotemporal accumulation of different sized NPs after TBI. Specifically, animal cohorts sustaining a controlled cortical impact injury received an intravenous injection of PEGylated NP cocktail (20, 40, 100, and 500 nm, each with a unique fluorophore) immediately (0 h), 2 h, 5 h, 12 h, or 23 h after injury. NPs were allowed to circulate for 1 h before perfusion and brain harvest. Confocal microscopy demonstrated peak NP accumulation within the injury penumbra 1 h post-injury. An inverse relationship was found between NP size and their continued accumulation within the penumbra. NP accumulation preferentially occurred in the primary motor and somatosensory areas of the injury penumbra as compared to the parietal association and visual area. Thus, we characterized the accumulation of particles up to 500 nm at different times acutely after injury, indicating the potential of NP-based TBI theranostics in the acute period after injury. PMID:27444615

  7. 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

  8. 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. PMID:26381440

  9. Mining experimental evidence of molecular function claims from the literature

    PubMed Central

    Crangle, Colleen E.; Cherry, J. Michael; Hong, Eurie L.; Zbyslaw, Alex; Wong, Limsoon

    2011-01-01

    Motivation The rate at which gene-related findings appear in the scientific literature makes it difficult if not impossible for biomedical scientists to keep fully informed and up to date. The importance of these findings argues for the development of automated methods that can find, extract and summarize this information. This article reports on methods for determining the molecular function claims that are being made in a scientific article, specifically those that are backed by experimental evidence. Results The most significant result is that for molecular function claims based on direct assays, our methods achieved recall of 70.7% and precision of 65.7%. Furthermore, our methods correctly identified in the text 44.6% of the specific molecular function claims backed up by direct assays, but with a precision of only 0.92%, a disappointing outcome that led to an examination of the different kinds of errors. These results were based on an analysis of 1823 articles from the literature of Saccharomyces cerevisiae (budding yeast). Availability The annotation files for S.cerevisiae are available from ftp://genome-ftp.stanford.edu/pub/yeast/data_download/literature_curation/gene_association.sgd.gz. The draft protocol vocabulary is available by request from the first author. Contact crangle@converspeech.com PMID:17942445

  10. 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

  11. 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. PMID:26501958

  12. The Nitrogen Legacy: Evidence of Soil Nitrogen Accumulation in Anthropogenic Landscapes

    NASA Astrophysics Data System (ADS)

    Van Meter, K. J.; Basu, N. B.

    2013-12-01

    Human modification of the nitrogen (N) cycle has resulted in increased flows of reactive N, with some suggesting that planetary boundaries for maintaining human and ecosystem health have been exceeded. Persistence of large hypoxic zones in inland and coastal waters created by elevated concentrations of nitrate is one of the most significant impacts of such increased flows. While the need to manage these flows and their associated ecological impacts is recognized, best management practices to reduce stream N concentrations have had only limited success. Some have attributed this lack of success to an accumulation of legacy N stores from decades of fertilizer application. Nitrogen mass balance studies seem to suggest an ongoing retention of N within anthropogenic landscapes, but the exact form and location of this legacy N and the associated retention rates are subject to question. Here we introduce an unprecedented analysis of long-term soil data from the Mississippi River Basin (MRB) revealing significant increases in total N (TN) content. We show that TN accumulation for the MRB accounts for 49% of net anthropogenic N inputs (NANI), which complements previous work indicating that approximately 25% of net inputs are lost as riverine output. These findings significantly reduce the uncertainty associated with basin-level N retention. Further, our results demonstrate that, despite conventional wisdom of intensive agriculture leading to a depletion of TN, an accumulation of N is occurring in the deeper subsurface (25 - 100 cm) that compensates for depletion in the plow layer (0-25 cm). These legacy N stores may lead to time lags between changes in management practices and decreasing N concentrations in stream waters, thus resulting in multidecadal effects on water quality in agricultural watersheds.

  13. Evidence for the Accumulation of Peroxidized Lipids in Membranes of Senescing Cotyledons 1

    PubMed Central

    Pauls, K. Peter; Thompson, John E.

    1984-01-01

    Fluorescent products of lipid peroxidation accumulate with age in microsomal membranes from senescing cotyledons of Phaseolus vulgaris. The temporal pattern of accumulation is closely correlated with a rise in the lipid phase transition temperature reflecting the formation of gel phase lipid. Increased levels of fluorescent peroxidation products are also detectable in total lipid extracts of senescent cotyledons. Lipoxygenase activity increases with advancing age by about 3-fold on a fresh weight basis and 4-fold on a dry weight basis indicating that the tissue acquires elevated levels of lipid hydroperoxides. As well, levels of glutathione and superoxide dismutase activity decline on a dry weight basis as the cotyledons age, rendering the tissue more susceptible to oxidative damage. Catalase activity rises initially and then declines during senescence, but peroxidase activity rises steeply. Thus, apart from this increase in peroxidase, which would scavenge H2O2 only if appropriate cosubstrates were available, the defense mechanisms for coping with activated oxygen species (O2−, H2O2, OH) are less effective in the older tissue. The observations support the contention that formation of gel phase lipid in senescing membranes is attributable to lipid peroxidation and suggest that the reactions of lipid peroxidation are utilized by the cotyledons to mediate deteriorative changes accompanying the mobilization and transport of metabolites from the storage tissue to the developing embryo. Images Fig. 10 PMID:16663749

  14. Experimental evidence for bedrock erosion by suspended sediment

    NASA Astrophysics Data System (ADS)

    Scheingross, J. S.; Brun, F.; Lo, D. Y.; Omerdin, K.; Lamb, M. P.

    2013-12-01

    Fluvial bedrock incision influences channel evolution and sets the pace of landscape lowering. Bedrock incision often occurs via abrasion, and existing theory is divided on the erosional efficiency of sediment transported in suspension versus bed load, due in part to a lack of data to test model predictions. This represents a major knowledge gap as suspended sediment can account for the majority of the total fluvial sediment load, and untested models make opposite predictions of bedrock erosion in steep channels and during large floods. We performed controlled abrasion mill experiments examining suspended and bed load erosion, making use of an erodible polyurethane foam substrate as a bedrock analog to overcome previous experimental limitations and allow for measureable suspension erosion. Our results show foam erodes similar to natural rock, where erodibility is a function of tensile strength and density. To explore the role of the mode of sediment transport on erosion, we varied sediment size from gravel (42 mm diameter) to medium sand (0.4 mm diameter), while holding fixed hydraulics, sediment load, and substrate strength. Under these conditions, volumetric erosion rates decreased across the bed load (~101 - 103 cm3/hr) to suspended load (~0.01 - 100 cm3/hr) transition due to lower near-bed sediment concentrations (~25 g/l vs. 115 g/l), slower settling velocity (0.09 m/s vs. 0.49 m/s), and viscous damping of impacts (for particle Stokes numbers less than ~75) for suspended particles. Our results provide direct experimental evidence of erosion by suspended load, and upscaling results to field scale shows suspension erosion can outpace bed load erosion by up to a factor ~4 during large floods which suspend coarse sand and gravel, and where suspended sediment dominates the total load. These results imply that suspension erosion may also dominate on very steep slopes where commonly used bedrock incision models (which ignore suspension erosion) predict zero erosion

  15. Experimental Methods to Estimate Accumulated Solids in Nuclear Waste Tanks - 13313

    SciTech Connect

    Duignan, Mark R.; Steeper, Timothy J.; Steimke, John L.

    2013-07-01

    The Department of Energy has a large number of nuclear waste tanks. It is important to know if fissionable materials can concentrate when waste is transferred from staging tanks prior to feeding waste treatment plants. Specifically, there is a concern that large, dense particles, e.g., plutonium containing, could accumulate in poorly mixed regions of a blend tank heel for tanks that employ mixing jet pumps. At the request of the DOE Hanford Tank Operations Contractor, Washington River Protection Solutions, the Engineering Development Laboratory of the Savannah River National Laboratory performed a scouting study in a 1/22-scale model of a waste tank to investigate this concern and to develop measurement techniques that could be applied in a more extensive study at a larger scale. Simulated waste tank solids and supernatant were charged to the test tank and rotating liquid jets were used to remove most of the solids. Then the volume and shape of the residual solids and the spatial concentration profiles for the surrogate for plutonium were measured. This paper discusses the overall test results, which indicated heavy solids only accumulate during the first few transfer cycles, along with the techniques and equipment designed and employed in the test. Those techniques include: - Magnetic particle separator to remove stainless steel solids, the plutonium surrogate from a flowing stream. - Magnetic wand used to manually remove stainless steel solids from samples and the tank heel. - Photographs were used to determine the volume and shape of the solids mounds by developing a composite of topographical areas. - Laser range finders to determine the volume and shape of the solids mounds. - Core sampler to determine the stainless steel solids distribution within the solids mounds. - Computer driven positioner that placed the laser range finders and the core sampler over solids mounds that accumulated on the bottom of a scaled staging tank in locations where jet velocities

  16. Experimental study of spontaneous release of accumulated energy in irradiated ices

    NASA Astrophysics Data System (ADS)

    Shabalin, E.; Kulagin, E.; Kulikov, S.; Melikhov, V.

    2003-06-01

    A phenomenon of spontaneous release of energy accumulated in some hydrogenous materials under fast neutron irradiation at low temperature was studied at a cryogenic irradiation facility of the IBR-2 reactor in Dubna for the purpose of cold neutron moderator development. Spontaneous release of energy occurred in water ice after 5-11 h of fast neutron irradiation at temperature <34 K and at absorbed dose rate 0.4 MGy/h. In contrast with previous data, no spontaneous burp was observed in solid methane.

  17. 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

  18. Decompression to altitude: assumptions, experimental evidence, and future directions.

    PubMed

    Foster, Philip P; Butler, Bruce D

    2009-02-01

    Although differences exist, hypobaric and hyperbaric exposures share common physiological, biochemical, and clinical features, and their comparison may provide further insight into the mechanisms of decompression stress. Although altitude decompression illness (DCI) has been experienced by high-altitude Air Force pilots and is common in ground-based experiments simulating decompression profiles of extravehicular activities (EVAs) or astronauts' space walks, no case has been reported during actual EVAs in the non-weight-bearing microgravity environment of orbital space missions. We are uncertain whether gravity influences decompression outcomes via nitrogen tissue washout or via alterations related to skeletal muscle activity. However, robust experimental evidence demonstrated the role of skeletal muscle exercise, activities, and/or movement in bubble formation and DCI occurrence. Dualism of effects of exercise, positive or negative, on bubble formation and DCI is a striking feature in hypobaric exposure. Therefore, the discussion and the structure of this review are centered on those highlighted unresolved topics about the relationship between muscle activity, decompression, and microgravity. This article also provides, in the context of altitude decompression, an overview of the role of denitrogenation, metabolic gases, gas micronuclei, stabilization of bubbles, biochemical pathways activated by bubbles, nitric oxide, oxygen, anthropometric or physiological variables, Doppler-detectable bubbles, and potential arterialization of bubbles. These findings and uncertainties will produce further physiological challenges to solve in order to line up for the programmed human return to the Moon, the preparation for human exploration of Mars, and the EVAs implementation in a non-zero gravity environment. PMID:19074573

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

    PubMed

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

    2015-08-01

    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

  20. 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

  1. Lifespan mercury accumulation pattern in Liza aurata : Evidence from two southern European estuaries

    NASA Astrophysics Data System (ADS)

    Tavares, S.; Oliveira, H.; Coelho, J. P.; Pereira, M. E.; Duarte, A. C.; Pardal, M. A.

    2011-10-01

    Mercury accumulation throughout the lifespan of Liza aurata (Risso, 1810) was analysed in four tissues (muscle, gills, liver and brain) in two southern European coastal ecosystems with distinct mercury contamination. Specimens from four to five age classes were captured in two sampling sites in the Ria de Aveiro (Laranjo bay and Mira), a system historically contaminated by industrial mercury, and in one site in the Mondego estuary, assumed as a mercury-free ecosystem. Mercury concentration in all tissues was found to be significantly higher in the Ria de Aveiro (Laranjo bay) compared to the Mondego, in accordance with the environmental contamination (water, sediments and suspended particulate matter). Significant differences inside the Ria de Aveiro (between the Mira and Laranjo bay) were only detected in the liver. This tissue registered the highest levels of mercury (ranging from 0.11 to 4.2 μg g -1 ) in all sampling sites, followed by muscle, brain, and gills. In all sampling sites and tissues was denoted a mercury dilution pattern along the lifecycle (except in liver at the Mondego, the reference area where the concentrations are always very low). An exponential trend was found in the metal age variation patterns in Laranjo (the most contaminated area) and a linear trend in the Mira and the Mondego (the least contaminated areas). Organic mercury concentration in muscle generally accounted for over 95% of total mercury concentration, and followed the same accumulation pattern of total mercury. This fish species is of lesser importance in mercury transfer to adjacent coastal areas and although the consumption of fish from Laranjo may present some risk for the humans, this risk decreases with fish age/size.

  2. Experimental and numerical investigations of the geometry influence on gas accumulation using a V-shaped forest model

    NASA Astrophysics Data System (ADS)

    Coudour, Bruno; Chetehouna, Khaled; Conan, Boris; Aubrun, Sandrine; Kaiss, Ahmed; Garo, Jean-Pierre

    2016-09-01

    Accumulation of gas inside a valley exposed to crosswind is experimented in this paper to extrapolate it to a case of a forest fire approaching a thalweg. Experimentations were done inside a wind tunnel using a 1/400 forest model configured as a valley with two different internal angles. The forest was modelled by mesh cylinders so that a parallel is possible with a real forest thanks to similitude laws. Gas emission was ensured by 400 tubes introduced inside the cylinders and supplied with ethane which acted as a tracer. The 400 tubes were divided into four independent parts of 100 tubes, inside and outside the valley, to be able to study independently the influence of the different zones of the forest model on the gas accumulation. We focused on the measurements of velocity by Laser-Doppler Velocimetry (LDV) and concentration with a Flame Ionization Detector (FID) to visualise the flow and quantify the accumulation of ethane. Analysing velocity, turbulence and concentration, a stagnation point was observed in the thalweg for the flattest valley and a recirculation zone for the deepest one where gas accumulation reached up to four times the concentration measured outside the valley due to airflow. The study of the influence of the different emission zones showed that gas accumulation mainly comes from the zones inside the valley. All these data permitted us to validate a numerical modelling which will enable us to study more cases, varying above all gas density but also choosing more valley angles and configurations. Another interest of the numerical model is the possibility of adding a thermal model.

  3. Rotational grazing on rangelands: Reconciliation of perception and experimental evidence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The experimental evaluation of grazing systems represents a highly visible and lengthy chapter in the history of the rangeland profession. Although experimentation has largely concluded, contrasting interpretations still remain regarding the potential benefits of rotational grazing systems on rangel...

  4. Accumulation and dissemination of prion protein in experimental sheep scrapie in the natural host

    PubMed Central

    Ryder, Stephen J; Dexter, Glenda E; Heasman, Lindsay; Warner, Richard; Moore, S Jo

    2009-01-01

    Background In order to study the sites of uptake and mechanisms of dissemination of scrapie prions in the natural host under controlled conditions, lambs aged 14 days and homozygous for the VRQ allele of the PrP gene were infected by the oral route. Infection occurred in all lambs with a remarkably short and highly consistent incubation period of approximately 6 months. Challenge of lambs at approximately eight months of age resulted in disease in all animals, but with more variable incubation periods averaging significantly longer than those challenged at 14 days. This model provides an excellent system in which to study the disease in the natural host by virtue of the relatively short incubation period and close resemblance to natural infection. Results Multiple sites of prion uptake were identified, of which the most important was the Peyer's patch of the distal ileum. Neuroinvasion was detected initially in the enteric nervous system prior to infection of the central nervous system. At end stage disease prion accumulation was widespread throughout the entire neuraxis, but vacuolar pathology was absent in most animals that developed disease at 6–7 months of age. Conclusion Initial spread of detectable PrP was consistent with drainage in afferent lymph to dependent lymph nodes. Subsequent accumulation of prions in lymphoid tissue not associated with the gut is consistent with haematogenous spread. In addition to macrophages and follicular dendritic cells, prion containing cells consistent with afferent lymph dendritic cells were identified and are suggested as a likely vehicle for carriage of prions from initial site of uptake to the lymphoreticular system, and as potential carriers of prion protein in blood. It is apparent that spongiform change, the characteristic lesion of scrapie and other prion diseases, is not responsible for the clinical signs in sheep, but may develop in an age dependent manner. PMID:19243608

  5. 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

  6. Error awareness revisited: accumulation of multimodal evidence from central and autonomic nervous systems.

    PubMed

    Wessel, Jan R; Danielmeier, Claudia; Ullsperger, Markus

    2011-10-01

    The differences between erroneous actions that are consciously perceived as errors and those that go unnoticed have recently become an issue in the field of performance monitoring. In EEG studies, error awareness has been suggested to influence the error positivity (Pe) of the response-locked event-related brain potential, a positive voltage deflection prominent approximately 300 msec after error commission, whereas the preceding error-related negativity (ERN) seemed to be unaffected by error awareness. Erroneous actions, in general, have been shown to promote several changes in ongoing autonomic nervous system (ANS) activity, yet such investigations have only rarely taken into account the question of subjective error awareness. In the first part of this study, heart rate, pupillometry, and EEG were recorded during an antisaccade task to measure autonomic arousal and activity of the CNS separately for perceived and unperceived errors. Contrary to our expectations, we observed differences in both Pe and ERN with respect to subjective error awareness. This was replicated in a second experiment, using a modified version of the same task. In line with our predictions, only perceived errors provoke the previously established post-error heart rate deceleration. Also, pupil size yields a more prominent dilatory effect after an erroneous saccade, which is also significantly larger for perceived than unperceived errors. On the basis of the ERP and ANS results as well as brain-behavior correlations, we suggest a novel interpretation of the implementation and emergence of error awareness in the brain. In our framework, several systems generate input signals (e.g., ERN, sensory input, proprioception) that influence the emergence of error awareness, which is then accumulated and presumably reflected in later potentials, such as the Pe. PMID:21268673

  7. Evidence for accumulated melt beneath the slow-spreading Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Sinha, M. C.; Navin, D. A.; MacGregor, L. M.; Constable, S.; Peirce, C.; White, A.; Heinson, G.; Inglis, M. A.

    The analysis of data from a multi-component geophysical experiment conducted on a segment of the slow-spreading (20 mm yr-1) Mid-Atlantic Ridge shows compelling evidence for a significant crustal magma body beneath the ridge axis. The role played by a crustal magma chamber beneath the axis in determining both the chemical and physical architecture of the newly formed crust is fundamental to our understanding of the accretion of oceanic lithosphere at spreading ridges, and over the last decade subsurface geophysical techniques have successfully imaged such magma chambers beneath a number of intermediate and fast spreading (60-140 mm yr-1 full rate) ridges. However, many similar geophysical studies of slow-spreading ridges have, to date, found little or no evidence for such a magma chamber beneath them. The experiment described here was carefully targeted on a magmatically active, axial volcanic ridge (AVR) segment of the Reykjanes Ridge, centred on 57 degrees 43 minutes North. It consisted of four major components: wide-angle seismic profiles using ocean bottom seismometers; seismic reflection profiles; controlled source electromagnetic sounding; and magneto-telluric sounding. Interpretation and modelling of the first three of these datasets shows that an anomalous body lies at a depth of between 2 and 3 km below the seafloor beneath the axis of the AVR. This body is characterized by anomalously low seismic P-wave velocity and electrical resistivity, and is associated with a seismic reflector. The geometry and extent of this melt body shows a number of similarities with the axial magma chambers observed beneath ridges spreading at much higher spreading rates. Magneto-telluric soundings confirm the existence of very low electrical resistivities in the crust beneath the AVR and also indicate a deeper zone of low resistivity within the upper mantle beneath the ridge.

  8. Target blood pressure in diabetes patients with hypertension--what is the accumulated evidence in 2011?

    PubMed

    Nilsson, Peter M

    2011-08-01

    There is overwhelming evidence that hypertension is an important risk factor for both macrovascular and microvascular complications in patients with diabetes, but the problem remains to identify appropriate goals for preventive therapies. A number of guidelines (the European Society of Cardiology (ESC)/European Association for the Study of Diabetes (EASD) 2007, the Joint National Committee (JNC)-VII 2003, the American Diabetes Association (ADA) 2011) have for example advocated a blood pressure goal of less than 130/80 mmHg, but this suggestion has been challenged by findings in recent trials and meta-analyses (2011). The European Society of Hypertension (ESH) therefore recommends a systolic blood pressure goal of "well below" 140 mmHg. Based on evidence from both randomized controlled trials (hypertension optimal treatment (HOT), action in diabetes and vascular disease: preterax and diamicron MR controlled evaluation (ADVANCE), action to control cardiovascular risk in diabetes (ACCORD)) and observational studies (ongoing telmisartan alone and in combination with ramipril global endpoint trial (ONTARGET), international verapamil-trandolapril study (INVEST), treat to new targets (TNT), and the National Diabetes Register (NDR)), it has been shown that the benefit for stroke reduction remains even at lower achieved blood pressure levels, but the risk of coronary events may be uninfluenced or even increased at lower systolic blood pressure levels. In a recent meta-analysis, it was therefore concluded that the new recommended goal should be 130-135 mmHg systolic blood pressure for most patients with type 2 diabetes. Other risk factors should also be controlled with a more ambitious strategy applied in the younger patients with shorter diabetes duration, but a more cautious approach in the elderly and frail patients with a number of vascular or non-vascular co-morbidities. In patients from East Asia, such as China, the stroke risk is relatively higher than the risk of

  9. Accumulating Evidence Supports a Taste Component for Free Fatty Acids in Humans

    PubMed Central

    Mattes, Richard D.

    2011-01-01

    The requisite criteria for what constitutes a taste primary have not been established. Recent advances in understanding of the mechanisms and functions of taste have prompted suggestions for an expanded list of unique taste sensations, including fat, or more specifically, free fatty acids (FFA). A set of criteria are proposed here and the data related to FFA are reviewed on each point. It is concluded that the data are moderate to strong that there are: A) adaptive advantages to FFA detection in the oral cavity; B) adequate concentrations of FFA to serve as taste stimuli; C) multiple complimentary putative FFA receptors on taste cells; D) signals generated by FFA that are conveyed by gustatory nerves; E) sensations generated by FFA that can be detected and scaled by psychophysical methods in humans when non-gustatory cues are masked; and F) physiological responses to oral fat/FFA exposure. On no point is there strong evidence challenging these observations. The reviewed findings are suggestive, albeit not definitive, that there is a taste component for FFA. PMID:21557960

  10. Age-dependent accumulation of lipofuscin in perivascular and subretinal microglia in experimental mice.

    PubMed

    Xu, Heping; Chen, Mei; Manivannan, Ayyakkannu; Lois, Noemi; Forrester, John V

    2008-01-01

    Fundus autofluorescence (AF) imaging by confocal scanning laser ophthalmoscopy has been widely used by ophthalmologists in the diagnosis/monitoring of various retinal disorders. It is believed that fundus AF is derived from lipofuscin in retinal pigment epithelial (RPE) cells; however, direct clinicopathological correlation has not been possible in humans. We examined fundus AF by confocal scanning laser ophthalmoscopy and confocal microscopy in normal C57BL/6 mice of different ages. Increasingly strong AF signals were observed with age in the neuroretina and subretinal/RPE layer by confocal scanning laser ophthalmoscopy. Unlike fundus AF detected in normal human subjects, mouse fundus AF appeared as discrete foci distributed throughout the retina. Most of the AF signals in the neuroretina were distributed around retinal vessels. Confocal microscopy of retinal and choroid/RPE flat mounts demonstrated that most of the AF signals were derived from Iba-1+ perivascular and subretinal microglia. An age-dependent accumulation of Iba-1+ microglia at the subretinal space was observed. Lipofuscin granules were detected in large numbers in subretinal microglia by electron microscopy. The number of AF+ microglia and the amount of AF granules/cell increased with age. AF granules/lipofuscin were also observed in RPE cells in mice older than 12 months, but the number of AF+ RPE cells was very low (1.48 mm(-2) and 5.02 mm(-2) for 12 and 24 months, respectively) compared to the number of AF+ microglial cells (20.63 mm(-2) and 76.36 mm(-2) for 6 and 24 months, respectively). The fluorescence emission fingerprints of AF granules in subretinal microglia were the same as those in RPE cells. Our observation suggests that perivascular and subretinal microglia are the main cells producing lipofuscin in normal aged mouse retina and are responsible for in vivo fundus AF. Microglia may play an important role in retinal aging and age-related retinal diseases. PMID:17988243

  11. Evolution of subgroup A respiratory syncytial virus: evidence for progressive accumulation of amino acid changes in the attachment protein.

    PubMed Central

    Cane, P A; Pringle, C R

    1995-01-01

    The variability of the attachment (G) proteins of 48 subgroup A isolates of respiratory syncytial virus (RSV) isolated over 38 years has been examined. Nucleotide sequences of two variable regions of the G protein genes were determined following amplification by PCR. The isolates showed temporal rather than geographical clustering, and there was evidence for progressive accumulation of amino acid changes at an average rate of approximately 0.25% per year estimated over the entire protein. The cocirculation of lineages of RSV at present appears to be the result of a process of evolution and survival of particular genotypes and the extinction of others. Analysis of reactivity of the isolates with monoclonal antibodies showed that their antigenic profiles closely paralleled their relatedness by nucleotide sequence, suggesting that antigenic drift due to immune selection may be occurring. PMID:7707517

  12. Evidence for the use of organic carbon as the sorbing matrix in the modeling of PCB accumulation in phytoplankton

    SciTech Connect

    Skoglung, R.S.; Swackhamer, D.L.

    1999-05-01

    This report presents empirical evidence for the use of organic carbon as the sorbing matrix in the kinetic modeling of PCB accumulation in phytoplankton. A kinetic-based model was used to predict congener-specific bioaccumulation factors of PCBs in phytoplankton samples collected from Green Bay, Lake Michigan. These values were compared to the measured bioaccumulation factors, and the sum of the residuals was used to evaluate the model`s predictive quality. The sorbing matrix fraction (F{sub M}) that minimized the sum of residuals of the model was then solved by iteration. The appropriateness of using dry weight, organic carbon fraction, or lipid fractions as the sorbing matrix fraction was determined by measuring their correlation to the optimum F{sub M}. It was determined that the F{sub M} correlated best with the organic carbon fraction, and this correlation appeared to be independent of both the spatial and seasonal differences of the field samples.

  13. Education and Cognitive Development: The Evidence from Experimental Research.

    ERIC Educational Resources Information Center

    Sharp, Donald; And Others

    1979-01-01

    Reports the results of a series of experimental studies and a sociodemographic survey designed to determine the relative influence of age and educational experience in the development of cognitive skills as manifested in formal, psychological experiments. (CM)

  14. Accidental release of fluoride into experimental pond and accumulation in sediments, plants, algae, molluscs and fish.

    PubMed

    Kudo, A; Garrec, J P

    1983-09-01

    The fate of fluoride in a simulated accidental release into an experimental pond was observed for 30 days in Grenoble, France. The components investigated were water, sediments, plants, algae, molluscs, and fish. Twenty-four hours after the release, most (99.8%) of the fluoride was distributed in the physical components (water and sediments), and the biological agents contained only 0.2% of the fluoride released. Despite an exposure to hot spots of 5000 ppm at the beginning of the accidental release, no visible toxic effects were observed on the biological components such as plants, algae, molluscs, and fish. The effects of the physical components in the defluoridation showed a significant role in the control the accidental release of fluoride in the aquatic system. PMID:6635267

  15. Accidental release of fluoride into experimental pond and accumulation in sediments, plants, algae, molluscs, and fish

    SciTech Connect

    Kudo, A.; Garrec, J.P.

    1983-09-01

    The fate of fluoride in a simulated accidental release into an experimental pond was observed for 30 days in Grenoble, France. The components investigated were water, sediments, plants, algae, molluscs, and fish. Twenty-four hours after the release, most (99.8%) of the fluoride was distributed in the physical components (water and sediments), and the biological agents contained only 0.2% of the fluoride released. Despite an exposure to hot spots of 5000 ppm at the beginning of the accidental release, no visible toxic effects were observed on the biological components such as plants, algae, molluscs, and fish. The effects of the physical components in the defluoridation showed a significant role in the control the accidental release of fluoride in the aquatic system.

  16. Herbicide-induced experimental variegate porphyria in mice: tissue porphyrinogen accumulation and response to porphyrogenic drugs.

    PubMed

    Krijt, J; Stranska, P; Maruna, P; Vokurka, M; Sanitrak, J

    1997-01-01

    Administration of oxadiazon or oxyfluorfen (1000 ppm in the diet) to male BALB/c mice for 9 days resulted in experimental porphyria, resembling the acute phase of human variegate porphyria. Urinary concentrations of 5-aminolevulinic acid and porphobilinogen reached 1500 and 3000 mumol/L, respectively. Both herbicides caused a decrease of protoporphyrinogen oxidase activity in liver and kidney. Brain protoporphyrinogen oxidase activity was not altered. Liver and kidney porphyrin content increased to 11 and 17 nmol/g, respectively (control mice, 2 nmol/g). Over 50% of liver and kidney porphyrins were in the reduced (porphyrinogen) form. Bile of oxadiazon-treated mice contained 700 nmol/mL of protoporphyrinogen (control mice, 15 nmol/mL). Porphyrin content of the trigeminal nerve increased from 1 nmol/g in control animals to 11 nmol/g in oxadiazon-treated animals, suggesting a possible contribution of peripheral nerve porphyrins to porphyric neuropathy. Mice treated with 125 ppm of oxadiazon in the diet for 9 days excreted moderately elevated levels of porphobilinogen in urine (control mice, less than 50 mumol/L; treated mice, 330 mumol/L). Administration of phenobarbital or phenytoin (single injections on days 7, 8, and 9) increased the urinary porphobilinogen concentration to 3500 mumol/L. This response to porphyrogenic drugs resembles the response observed in human acute porphyrias. PMID:9431441

  17. Experimental model of microcystin accumulation in the liver of Oreochromis niloticus exposed subchronically to a toxic bloom of Microcystis sp.

    PubMed

    Deblois, Charles P; Giani, Alessandra; Bird, David F

    2011-05-01

    Although accumulation of the liver toxin microcystin in phytoplanktivorous fish has been demonstrated in captive fish and in natural ecosystems, the relation between microcystin in ingested algae and the pattern of buildup of microcystin in fish is poorly known. In this month-long study performed at a Brazilian fish farm, 45 mature Oreochromis niloticus were fed daily with fresh seston periodically dominated by toxic Microcystis sp. Microcystin was measured daily in the food and every 5 days in liver and muscle samples. Control fish received a diet of seston that was low in toxic cyanobacteria. Initially, in treatment ponds, microcystin available for fish increased from 6.5 to 66.9 ng microcystin fish(-1)day(-1), which was accompanied by an increase from 5.5 to 35.4 ng microcysting liver(-1). Microcystin in muscle was below our detection limit of 4 ng g tissue(-1) for the entire study. In the bloom phase, available microcystin reached its highest concentration (4450 ng MC fish(-1)day(-1)) then decreased to 910 ng microcystin fish(-1)day(-1) on day 31. During this period, microcystin reached its highest concentration of 81.6 ng MC g liver(-1) and stayed high until the end of the experiment. A model based on rapid uptake, saturation, and exponential loss was built with these experimental results, and verified with data from the literature. Our model showed that accumulation was up to 50% of ingestion at low doses, but at intermediate doses, the onset of elimination led to a decline of liver burden. Although the accumulation rate confirms the high contamination potential of microcystin, it was balanced by a high depuration rate and this efficient systemic elimination may explain the tolerance of these fish to toxic blooms in the wild. PMID:21392496

  18. Bacteria are not too small for spatial sensing of chemical gradients: An experimental evidence

    PubMed Central

    Thar, Roland; Kühl, Michael

    2003-01-01

    By analyzing the chemotactic behavior of a recently described marine bacterial species, we provide experimental evidence that bacteria are not too small for sensing chemical gradients spatially. The bipolar flagellated vibrioid bacteria (typical size 2 × 6 μm) exhibit a unique motility pattern as they translate along as well as rotate around their short axis, i.e., the pathways of the cell poles describe a double helix. The natural habitat of the bacteria is characterized by steep oxygen gradients where they accumulate in a band at their preferred oxygen concentration of ≈2 μM. Single cells leaving the band toward the oxic region typically return to the band within 16 s following a U-shaped track. A detailed analysis of the tracks reveals that the cells must be able to sense the oxygen gradient perpendicular to their swimming direction. Thus, they can detect oxygen gradients along a distance of ≈5 μm corresponding to the extension of their long axis. The observed behavior can be explained by the presence of two independent sensor regions at either cell pole that modulate the rotation speed of the polar flagellar bundles, i.e., the flagellar bundle at the cell pole exposed to higher oxygen concentration is rotating faster than the other bundle. A mathematical model based on these assumptions reproduces the observed swimming behavior of the bacteria. PMID:12719518

  19. 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.

  20. Bilateral oligopoly in pollution permit markets - experimental evidence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  1. Experimental evidence of antiphase population dynamics in lasers

    SciTech Connect

    Cabrera, Eduardo; Calderon, Oscar G.; Guerra, J.M.

    2005-10-15

    We report a direct experimental observation of antiphase oscillations in population dynamics in lasers. We show that these population oscillations are intrinsically related to the well-known antiphase polarization dynamics, i.e., the antiphase oscillations of two orthogonal polarization laser field states. We have used a class B Nd:YAG (yttrium aluminum garnet) laser.

  2. Bilateral oligopoly in pollution permit markets: experimental evidence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  3. Antigenic variation in Treponema pallidum: TprK sequence diversity accumulates in response to immune pressure during experimental syphilis1

    PubMed Central

    Giacani, Lorenzo; Molini, Barbara J.; Kim, Eric Y.; Godornes, B. Charmie; Leader, B. Troy; Tantalo, Lauren C.; Centurion-Lara, Arturo; Lukehart, Sheila A.

    2010-01-01

    Pathogens that cause chronic infections often employ antigenic variation to evade the immune response and persist in the host. In Treponema pallidum (T. pallidum), the causative agent of syphilis, the TprK antigen undergoes variation of seven variable regions (V1-V7) by nonreciprocal recombination of silent donor cassettes with the tprK expression site. These V regions are the targets of the host humoral immune response during experimental infection. The present study addresses the causal role of the acquired immune response in the selection of TprK variants in two ways: 1) by investigating TprK variants arising in immunocompetent vs immunosuppressed hosts, and 2) by investigating the effect of prior specific immunization on selection of TprK variants during infection. V region diversity, particularly in V6, accumulates more rapidly in immunocompetent rabbits than in pharmacologically immunosuppressed rabbits (treated with weekly injections of methylprednisolone acetate). In a complementary experiment, rabbits pre-immunized with V6 region synthetic peptides had more rapid accumulation of V6 variant treponemes than control rabbits. These studies demonstrate that the host immune response selects against specific TprK epitopes expressed on T. pallidum, resulting in immune selection of new TprK variants during infection, confirming a role for antigenic variation in syphilis. PMID:20190145

  4. 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. PMID:26121619

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

    PubMed Central

    Savage, James L.; Russell, Andrew F.; Townsend, Simon W.

    2015-01-01

    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. PMID:26121619

  6. 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. PMID:19484211

  7. 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.

  8. 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

  9. 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

  10. Experimental evidence of warm electron populations in magnetron sputtering plasmas

    SciTech Connect

    Sahu, B. B. Han, Jeon G.; Kim, Hye R.; Ishikawa, K.; Hori, M.

    2015-01-21

    This work report on the results obtained using the Langmuir probe (LP) measurements in high-power dc magnetron sputtering discharges. Data show clear evidence of two electron components, such as warm and bulk electrons, in the sputtering plasma in a magnetic trap. We have also used optical emission spectroscopy diagnostic method along with LP to investigate the plasma production. Data show that there is a presence of low-frequency oscillations in the 2–3 MHz range, which are expected to be generated by high-frequency waves. Analysis also suggests that the warm electrons, in the plasmas, can be formed due to the collisionless Landau damping of the bulk electrons.

  11. 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

  12. Influence of Vegetation on Sediment Accumulation in Restored Tidal Saltmarshes: Field Evidence from the Blackwater Estuary, Essex, UK

    NASA Astrophysics Data System (ADS)

    Price, D.; French, J.; Burningham, H.

    2013-12-01

    Tidal saltmarshes in the UK, and especially in the estuaries of southeast England, have been subject to degradation and erosion over the last few decades, primarily caused by sea-level rise and coastal squeeze due to fixed coastal defences. This is of great concern to a range of coastal stakeholders due to the corresponding loss of functions and services associated with these systems. The coastal defence role that saltmarshes play is well established, and the importance of saltmarsh ecosystems as habitats for birds, fish, and other species is evidenced in the fact that a large proportion of saltmarsh in the southeast England is designated for its scientific and conservation significance. Sediment accumulation is critical for the maintenance of marsh elevation within the tidal frame and for delivery of the aforementioned functions and services. Although many studies have examined accumulation processes, key questions have yet to be fully tested through intensive field observations. One such question relates to the role of vegetation in mediating the retention of newly introduced sediment, as recent research has called into doubt the traditional view of halophytes significantly enhancing rates of sedimentation through wave dissipation. This study presents early results from a project designed to advance our understanding of the processes controlling sediment accumulation. The research focuses on the UK's first large-scale experimental managed flood defence realignment at Tollesbury, Blackwater estuary, Essex. The seawall protecting 21ha of reclaimed agricultural land was artificially breached in 1995 and saltmarsh has progressively developed as tidal exchange has introduced fine sediment into the site. Results from a 12 month monitoring campaign involving hierarchical two-week sediment trap deployments indicates that the role of vegetation in marsh development is less clear cut that previously thought. Gross sedimentation rates were generally higher in non

  13. NEW EXPERIMENTAL EVIDENCES ABOUT THE FORMATION AND CONSUMPTION OF KETOHYDROPEROXIDES

    PubMed Central

    Battin-Leclerc, Frédérique; Herbinet, Olivier; Glaude, Pierre-Alexandre; Fournet, René; Zhou, Zhongyue; Deng, Liulin; Guo, Huijun; Xie, Mingfeng; Qi, Fei

    2013-01-01

    The formation of hydroperoxides postulated in all the kinetic models for the low temperature oxidation of alkanes have been experimentally proved thanks to a new type of apparatus associating a quartz jet-stirred reactor through a molecular-beam sampling system to a reflectron time-of-flight mass spectrometer combined with tunable synchrotron vacuum ultraviolet photoionization. This apparatus has been used to investigate the low-temperature oxidation of n-butane and has allowed demonstrating the formation of different types of alkylhydroperoxides, namely methylhydroperoxide, ethylhydroperoxide and butylhydroperoxide, and of C4 alkylhydroperoxides including a carbonyl function (ketohydroperoxides). In addition, the formation of products deriving from these ketohydroperoxides, such as C4 molecules including either two carbonyl groups or one carbonyl and one alcohol functions, has been observed. Simulations using a detailed kinetic model have been performed to support some of the assumptions made in this work. PMID:23700382

  14. Experimental Evidence of Fermi-Luttinger Liquid State.

    NASA Astrophysics Data System (ADS)

    Debray, Philippe; Muhammad, Mustafa; Herbert, Steven; Newrock, Richard

    2008-03-01

    We have measured Coulomb drag between spatially separated parallel quantum wires, made on AlGaAs/GaAs heterostructures by the split-gate technique, in the absence of tunneling to experimentally probe drag by small forward momentum transfer. Drag between wires of lengths 500 and 300 nm was measured in the one-dimensional transport regime at temperatures in the range 30 mK -- 1.2 K. We have observed both positive and negative drag. The temperature dependence of drag of both types is in excellent agreement with that predicted by the recently proposed Fermi-Luttinger liquid (FLL) theory that takes into account the curvature in the fermionic dispersion. Positive drag occurs when the curvature is positive, while negative drag occurs when it is negative.

  15. 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

  16. Experimental evidence for radiation pressure on a macroscopic dielectric

    NASA Astrophysics Data System (ADS)

    García-Segundo, C.; Ramos-Ortiz, G.; Villagrán-Muniz, M.

    2003-09-01

    We have detected acoustic signals produced by laser pulses on a macroscopic glass slab, obtaining amplitudes, as function of the angle of incidence, denoted as Hp and Hs depending on the polarization orientations of the pulsed pumping laser, p and s, respectively. The relative behaviour of these curves is related to radiation pressure rather than pure absorption, in the same manner as predicted theoretically in the literature [A Treatise on Electricity and Magnetism, Dover Publications, New York, 1891; Phys. Rep. 52 (1979) 133; Opt. Commun. 58 (1986) 59]. In a second experiment, based on a CW Michelson interferometer, where one of the mirrors is a glass slab pumped at the Brewster angle with the pulsed beam, we verified qualitatively the relationship observed for the Hp and Hs acoustic experimental data.

  17. Experimental evidence for the thermophilicity of ancestral life

    PubMed Central

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

    2013-01-01

    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. PMID:23776221

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

    PubMed

    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. PMID:26138970

  19. 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. PMID:27442516

  20. Experimental evidence of homonuclear bonds in amorphous GaN

    SciTech Connect

    Ishimaru, Dr. Manabu; Zhang, Yanwen; Wang, Xuemei; Chu, Wei-Kan; Weber, William J

    2011-01-01

    Although GaN is an important semiconductor material, its amorphous structures are not well understood. Currently, theoretical atomistic structural models which contradict each other, are proposed for the chemical short-range order of amorphous GaN: one characterizes amorphous GaN networks as highly chemically ordered, consisting of heteronuclear Ga-N atomic bonds; and the other predicts the existence of a large number of homonuclear bonds within the first coordination shell. In the present study, we examine amorphous structures of GaN via radial distribution functions obtained by electron diffraction techniques. The experimental results demonstrate that amorphous GaN networks consist of heterononuclear Ga-N bonds, as well as homonuclear Ga-Ga and N-N bonds.

  1. Experimental evidence of indirect transmission of Mycoplasma synoviae.

    PubMed

    Marois, Corinne; Picault, Jean-Paul; Kobisch, Marylène; Kempf, Isabelle

    2005-01-01

    The aim of the study was to analyse experimental transmission of Mycoplasma synoviae, an avian pathogen. Three experiments using specific pathogen-free day-old chicks placed in isolators were conducted. In the first experiment, the birds were introduced in an isolator previously contaminated with a M. synoviae broth culture. After 34 days, these birds were eliminated and, for the second trial, the chicks were introduced in the same isolator without disinfecting. In the third assay, the chicks were placed in an isolator containing a mixture of food, feathers and dust collected less than an hour earlier from a M. synoviae infected laying hen flock. In the second and third experiments in order to exacerbate the M. synoviae infection, the birds were inoculated with infectious bronchitis (IB) virus. The presence of M. synoviae in the environment and in tracheal swabs was monitored by culture, a multiplex PCR (mPCR) detecting M. synoviae and Mycoplasma 16S rDNA and a multiplex RT-PCR (mRT-PCR) detecting the M. synoviae mRNA coding for a membrane protein and Mycoplasma 16S rRNA. In in vitro experimental conditions, M. synoviae mRNA and 16S rRNA were detected up to 20 min and 23 h respectively after mycoplasma death. In the first assay, the first infected bird was detected on the 13th day. In the second trial, culturable M. synoviae or viable M. synoviae were detected in the isolator for 3 or 4 to 5 days respectively after depopulation of the birds of the first assay whereas the first culture positive tracheal swabs were detected on the 33rd day, after IB inoculation. In the third experiment, the first infected birds were detected on the 54th day. Thus, the different assays showed that M. synoviae contaminated material (dust, feathers and food) can infect chicks, sometimes after remarkably long silent periods. PMID:16120251

  2. Experimental evidence of energetic neutrals production in an ion diode

    NASA Astrophysics Data System (ADS)

    Pushkarev, A. I.; Isakova, Y. I.; Khaylov, I. P.

    2015-01-01

    The paper presents several experimental proofs of the formation of energetic charge-exchange neutrals in a self-magnetically insulated ion diode with a graphite cathode. The energetic neutrals are thought to be produced as a result of charge exchange process between accelerated ions and stationary neutral molecules. The experiments have been carried out using both a diode with externally applied magnetic insulation (single-pulse mode: 100 ns, 250-300 kV) and a diode with self-magnetic insulation (double-pulse mode: 300-500 ns, 100-150 kV (negative pulse); 120 ns, 250-300 kV (positive pulse)). The motivation for looking at the neutral component of the ion beam came when we compared two independent methods to measure the energy density of the beam. A quantitative comparison of infrared measurements with signals from Faraday cups and diode voltage was made to assess the presence of neutral atoms in the ion beam. As another proof of charge-exchange effects in ion diode we present the results of statistical analysis of diode performance. It was found that the shot-to shot variation of the energy density in a set of 50-100 shots does not exceed 11%, whilst the same variation for ion current density was 20-30%; suggesting the presence of neutrals in the beam. Moreover, the pressure in the zone of ion beam energy dissipation exceeds the results stated in cited references. The difference between our experimental data and results stated by other authors we attribute to the presence of a low-energy charge-exchange neutral component in the ion beam.

  3. 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. PMID:17605588

  4. Activity in Inferior Parietal and Medial Prefrontal Cortex Signals the Accumulation of Evidence in a Probability Learning Task

    PubMed Central

    d'Acremont, Mathieu; Fornari, Eleonora; Bossaerts, Peter

    2013-01-01

    In an uncertain environment, probabilities are key to predicting future events and making adaptive choices. However, little is known about how humans learn such probabilities and where and how they are encoded in the brain, especially when they concern more than two outcomes. During functional magnetic resonance imaging (fMRI), young adults learned the probabilities of uncertain stimuli through repetitive sampling. Stimuli represented payoffs and participants had to predict their occurrence to maximize their earnings. Choices indicated loss and risk aversion but unbiased estimation of probabilities. BOLD response in medial prefrontal cortex and angular gyri increased linearly with the probability of the currently observed stimulus, untainted by its value. Connectivity analyses during rest and task revealed that these regions belonged to the default mode network. The activation of past outcomes in memory is evoked as a possible mechanism to explain the engagement of the default mode network in probability learning. A BOLD response relating to value was detected only at decision time, mainly in striatum. It is concluded that activity in inferior parietal and medial prefrontal cortex reflects the amount of evidence accumulated in favor of competing and uncertain outcomes. PMID:23401673

  5. Experimental evidence of a delta-shock in nonlinear chromatography

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A

    2010-01-01

    We report about a new type of composition front in nonlinear chromatography that is called delta-shock, which has to be added to the family of classical transitions, i.e. simple waves, shocks and semi-shocks. Recently, the occurrence of delta-shocks in the case of mixed competitive-cooperative isotherms of the following type n{sub i} = H{sub i}c{sub i}/1 = K{sub 1}c{sub 1} + K{sub 2}c{sub 2} (i = 1,2), (with H{sub 2} > H{sub 1}, where components 1 and 2 have anti-Langmuir and Langmuir adsorption behavior, respectively) was predicted theoretically and their behavior was analyzed in the frame of the equilibrium theory of chromatography. The delta-shock can be viewed as a growing traveling spike superimposed to the discontinuity separating the initial and the feed state, which propagates along the column at constant speed and constant rate of growth. In this work we complement these findings from an experimental point of view. The binary system consisting of phenetole (component 1) and 4-tert-butylphenol (component 2) in methanol-water (about 2:1, v/v) on a Zorbax 300StableBond-C18 column from Agilent has been shown, through a series of overloaded pulse experiments and of frontal analysis experiments with the pure compounds, to be subject to the competitive-cooperative isotherm of the type above, up to rather large concentrations. This system does exhibit adelta-shock when the operating conditions are chosen according to theory, namely when phenetole initially saturating the column is displaced by 4-tert-butylphenol, both at high concentrations (the minimum concentrations exhibiting a fully developed delta-shock in this series of experiments were c{sub 1} = 20 g/L and c{sub 2} = 75 g/L). The propagation of the delta-shock matches the theoretical predictions in terms of both the effect of concentration and the effect of column length. This is the first experimental observation ever of adelta-shock in chromatography. It is noteworthy that the proof of the occurrence of

  6. Physical description of boundary-layer transition: Experimental evidence

    NASA Technical Reports Server (NTRS)

    Saric, William S.

    1994-01-01

    The problems of understanding the origins of turbulent flow and transition to turbulent flow are the most important unsolved problems of fluid mechanics and aerodynamics. It is well known that the stability, transition, and turbulent characteristics of bounded shear layers are fundamentally different from those of free shear layers. Likewise, the stability, transition, and turbulent characteristics of open systems are fundamentally different from those of closed systems. Because of the influence of indigenous disturbances, surface geometry and roughness, sound, heat transfer, and ablation, it is not possible to develop general prediction schemes for transition location and the nature of turbulent structures in boundary-layer flows. At the present time no mathematical model exists that can predict the transition Reynolds number on a flat plate. The recent progress in this area is encouraging, in that a number of distinct transition mechanisms have been found experimentally. The theoretical work finds them to be amplitude and Reynolds-number dependent. The theory remains rather incomplete with regard to predicting transition. Amplitude and spectral characteristics of the disturbances inside the laminar viscous layer strongly influence which type of transition occurs. The major need in this area is to understand how freestream disturbances are entrained into the boundary layer, i.e., to answer the question of receptivity. We refer receptivity to the mechanism(s) that cause freestream disturbances to enter the boundary layer and create the initial amplitudes for unstable waves.

  7. [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. PMID:24206254

  8. Gender differences in cooperation: experimental evidence on high school students.

    PubMed

    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

  9. 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.

  10. Locally delivered CD40 agonist antibody accumulates in secondary lymphoid organs and eradicates experimental disseminated bladder cancer.

    PubMed

    Sandin, Linda C; Orlova, Anna; Gustafsson, Erika; Ellmark, Peter; Tolmachev, Vladimir; Tötterman, Thomas H; Mangsbo, Sara M

    2014-01-01

    Immunotherapy with intratumoral injection of adenoviral vectors expressing CD40L has yielded positive results in experimental and clinical bladder cancer. We therefore hypothesized that anti-CD40 antibody would be effective in this setting. Agonistic CD40 antibodies were developed as vaccine adjuvants but have later been used as treatment of advanced solid tumors and hematologic cancers. Systemic anti-CD40 therapy has been associated with immune-related adverse events, such as cytokine release syndrome and liver toxicity, and local delivery is an attractive approach that could reduce toxicity. Herein, we compared local and systemic anti-CD40 antibody delivery to evaluate efficacy, toxicity, and biodistribution in the experimental MB49 bladder cancer model. Antitumor effects were confirmed in the B16 model. In terms of antitumor efficacy, local anti-CD40 antibody stimulation was superior to systemic therapy at an equivalent dose and CD8 T cells were crucial for tumor growth inhibition. Both administration routes were dependent on host CD40 expression for therapeutic efficacy. In vivo biodistribution studies revealed CD40-specific antibody accumulation in the tumor-draining lymph nodes and the spleen, most likely reflecting organs with frequent target antigen-expressing immune cells. Systemic administration led to higher antibody concentrations in the liver and blood compared with local delivery, and was associated with elevated levels of serum haptoglobin. Despite the lack of a slow-release system, local anti-CD40 therapy was dependent on tumor antigen at the injection site for clearance of distant tumors. To summarize, local low-dose administration of anti-CD40 antibody mediates antitumor effects in murine models with reduced toxicity and may represent an attractive treatment alternative in the clinic. PMID:24778163

  11. Increased expression of host iron-binding proteins precedes iron accumulation and calcification of primary lung lesions in experimental tuberculosis in the guinea pig

    PubMed Central

    Basaraba, Randall J.; Bielefeldt-Ohmann, Helle; Eschelbach, Ellie K.; Reisenhauer, Claire; Tolnay, Airn E.; C.Taraba, Lauren; Shanley, Crystal A.; Smith, Erin A.; Bedwell, Cathy L.; Chlipala, Elizabeth A.; Orme, Ian M.

    2008-01-01

    The growth and virulence of Mycobacterium tuberculosis depends on its ability to scavenge host iron, an essential and limited micronutrient in vivo. In this study we show that ferric iron accumulates both intra- and extra-cellularly in the primary lung lesions of guinea pigs aerosol-infected with the H37Rv strain of Mycobacterium tuberculosis. Iron accumulated within macrophages at the periphery of the primary granulomatous lesions while extra-cellular ferric iron was concentrated in areas of lesion necrosis. Accumulation of iron within primary lesions was preceded by an increase in expression of heavy chain (H) ferritin, lactoferrin and receptors for transferrin, primarily by macrophages and granulocytes. The increased expression of intra-cellular H ferritin and extra-cellular lactoferrin, more so than transferrin receptor, paralleled the development of necrosis within primary lesions. The deposition of extra-cellular ferric iron within necrotic foci coincided with the accumulation of calcium and phosphorus and other cations in the form of dystrophic calcification. Primary lung lesions from guinea pigs vaccinated with Mycobactrium bovis BCG prior to experimental infection, had reduced iron accumulation as well as H ferritin, lactoferrin and transferrin receptor expression. The amelioration of primary lesion necrosis and dystrophic calcification by BCG vaccination was coincident with the lack of extra-cellular ferric iron and lactoferrin accumulation. These data demonstrate that BCG vaccination ameliorates primary lesion necrosis, dystrophic mineralization and iron accumulation, in part by down-regulating the expression of macrophage H ferritin, lactoferrin and transferrin receptors, in vivo. PMID:17942369

  12. Lead accumulation in feathers of nestling black-crowned night-herons (Nycticorax nycticorax) experimentally treated in the field

    USGS Publications Warehouse

    Golden, N.H.; Rattner, B.A.; Cohen, J.B.; Hoffman, D.J.; Russek-Cohen, E.; Ottinger, M.A.

    2003-01-01

    Although lead can attain high concentrations in feathers, interpretation of the biological significance of this phenomenon is difficult. As part of an effort to develop and validate non-invasive methods to monitor contaminant exposure in free-ranging birds, lead uptake by feathers of nestling black-crowned night-herons (Nycticorax nycticorax) was evaluated in a controlled exposure study. Four to six day-old heron nestlings (one/nest) at Chincoteague Bay, Virginia, received a single intraperitoneal injection of dosing vehicle (control; n=7) or a dose of lead nitrate in water (0.01, 0.05, or 0.25 mg Pb/g body weight of nestling; n=6 or 7/dose) chosen to yield feather lead concentrations found at low to moderately polluted sites. Nestlings were euthanized at 15 days of age. Lead accumulation in feathers was associated with concentrations in bone, kidney, and liver (r = 0.32 - 0.74, p < 0.02), but exhibited only modest dose-dependence. Blood delta-aminolevulinic acid dehydratase activity was inhibited by lead, although effects on other biochemical endpoints were marginal. Tarsus growth rate was inversely related to feather lead concentration. Culmen growth rate was depressed in nestlings treated with the highest dose of lead, but not correlated with feather lead concentration. These findings provide evidence that feathers of nestling herons are a sensitive indicator of lead exposure and have potential application for the extrapolation of lead concentrations in other tissues and the estimation of environmental lead exposure in birds.

  13. Molecular chaperone accumulation as a function of stress evidences adaptation to high hydrostatic pressure in the piezophilic archaeon Thermococcus barophilus

    PubMed Central

    Cario, Anaïs; Jebbar, Mohamed; Thiel, Axel; Kervarec, Nelly; Oger, Phil M.

    2016-01-01

    The accumulation of mannosyl-glycerate (MG), the salinity stress response osmolyte of Thermococcales, was investigated as a function of hydrostatic pressure in Thermococcus barophilus strain MP, a hyperthermophilic, piezophilic archaeon isolated from the Snake Pit site (MAR), which grows optimally at 40 MPa. Strain MP accumulated MG primarily in response to salinity stress, but in contrast to other Thermococcales, MG was also accumulated in response to thermal stress. MG accumulation peaked for combined stresses. The accumulation of MG was drastically increased under sub-optimal hydrostatic pressure conditions, demonstrating that low pressure is perceived as a stress in this piezophile, and that the proteome of T. barophilus is low-pressure sensitive. MG accumulation was strongly reduced under supra-optimal pressure conditions clearly demonstrating the structural adaptation of this proteome to high hydrostatic pressure. The lack of MG synthesis only slightly altered the growth characteristics of two different MG synthesis deletion mutants. No shift to other osmolytes was observed. Altogether our observations suggest that the salinity stress response in T. barophilus is not essential and may be under negative selective pressure, similarly to what has been observed for its thermal stress response. PMID:27378270

  14. Molecular chaperone accumulation as a function of stress evidences adaptation to high hydrostatic pressure in the piezophilic archaeon Thermococcus barophilus.

    PubMed

    Cario, Anaïs; Jebbar, Mohamed; Thiel, Axel; Kervarec, Nelly; Oger, Phil M

    2016-01-01

    The accumulation of mannosyl-glycerate (MG), the salinity stress response osmolyte of Thermococcales, was investigated as a function of hydrostatic pressure in Thermococcus barophilus strain MP, a hyperthermophilic, piezophilic archaeon isolated from the Snake Pit site (MAR), which grows optimally at 40 MPa. Strain MP accumulated MG primarily in response to salinity stress, but in contrast to other Thermococcales, MG was also accumulated in response to thermal stress. MG accumulation peaked for combined stresses. The accumulation of MG was drastically increased under sub-optimal hydrostatic pressure conditions, demonstrating that low pressure is perceived as a stress in this piezophile, and that the proteome of T. barophilus is low-pressure sensitive. MG accumulation was strongly reduced under supra-optimal pressure conditions clearly demonstrating the structural adaptation of this proteome to high hydrostatic pressure. The lack of MG synthesis only slightly altered the growth characteristics of two different MG synthesis deletion mutants. No shift to other osmolytes was observed. Altogether our observations suggest that the salinity stress response in T. barophilus is not essential and may be under negative selective pressure, similarly to what has been observed for its thermal stress response. PMID:27378270

  15. Experimental Evidence for LENR in a Polarized Pd/D Lattice

    NASA Astrophysics Data System (ADS)

    Szpak, S.

    2005-03-01

    Experimental evidence in support of claims that excess enthalpy production in a polarized Pd/D lattice is of a nuclear origin is questioned on various grounds, eg marginal intensity and difficulty in reproducing. Here, evidence is presented that is 100% reproducible and of sufficient intensity to be well outside of experimental errors. In addition to the thermal behavior, the nuclear manifestations include: X-ray emission; tritium production; and, when an operating cell is placed in an external electric field, fusion to create heavier metals such as Ca, Al, Mg, and Zn.

  16. Evidence for chaos in an experimental time series from serrated plastic flow

    NASA Astrophysics Data System (ADS)

    Venkadesan, S.; Valsakumar, M. C.; Murthy, K. P. N.; Rajasekar, S.

    1996-07-01

    An experimental time series from a tensile test of an Al-Mg alloy in the serrated plastic flow domain is analyzed for signature of chaos. We employ state space reconstruction by embedding of time delay vectors. The minimum embedding dimension is found to be 4 and the largest Lyapunov exponent is positive, thereby providing prima facie evidence for chaos in an experimental time series of serrated plastic flow data.

  17. 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

  18. 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. PMID:26800032

  19. Electric field driven fractal growth in polymer electrolyte composites: Experimental evidence of theoretical simulations

    NASA Astrophysics Data System (ADS)

    Dawar, Anit; Chandra, Amita

    2012-11-01

    The influence of electric field on the diffusion limited aggregation has been observed experimentally. The observation provides experimental confirmation of the theoretical model proposed by Zhi-Jie Tan et al. [Phys. Lett. A 268 (2000) 112]. Most strikingly, a transition from a disordered ramified pattern to an ordered pattern (chain-like growth) has been observed. The growth is governed by diffusion, convection and migration in an electric field which give rise to the different patterns. This Letter can also be considered as an experimental evidence of computer simulated fractal growth given by Huang and Hibbert [Physica A 233 (1996) 888].

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

    SciTech Connect

    Mangiarotti, A.

    2009-06-03

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

  1. 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 India to…

  2. 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.

  3. Teacher Incentives in Developing Countries: Experimental Evidence from Kenya. 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 Kenya"--a paper presented at the National Center on Performance Incentives research to policy conference in February--Paul Glewwe (University of Minnesota), Nauman Illias (The Brattle Group), and Michael Kremer (Harvard University) review findings from recent research in…

  4. Teacher Incentives in Developing Countries: Recent Experimental Evidence from Kenya. Working Paper 2008-09

    ERIC Educational Resources Information Center

    Glewwe, Paul; Ilias, Nauman; Kremer, Michael

    2008-01-01

    This paper reviews recent evidence on the impact of a teacher incentives program in Kenya. The results are based on a randomized trial, which removes many sources of bias that can arise in analyses of non-experimental data. One hundred schools in a rural area were randomly divided into 50 that participated in a teacher incentives program and 50…

  5. Accumulate repeat accumulate codes

    NASA Technical Reports Server (NTRS)

    Abbasfar, Aliazam; Divsalar, Dariush; Yao, Kung

    2004-01-01

    In this paper we propose an innovative channel coding scheme called 'Accumulate Repeat Accumulate codes' (ARA). This class of codes can be viewed as serial turbo-like codes, or as a subclass of Low Density Parity Check (LDPC) codes, thus belief propagation can be used for iterative decoding of ARA codes on a graph. The structure of encoder for this class can be viewed as precoded Repeat Accumulate (RA) code or as precoded Irregular Repeat Accumulate (IRA) code, where simply an accumulator is chosen as a precoder. Thus ARA codes have simple, and very fast encoder structure when they representing LDPC codes. Based on density evolution for LDPC codes through some examples for ARA codes, we show that for maximum variable node degree 5 a minimum bit SNR as low as 0.08 dB from channel capacity for rate 1/2 can be achieved as the block size goes to infinity. Thus based on fixed low maximum variable node degree, its threshold outperforms not only the RA and IRA codes but also the best known LDPC codes with the dame maximum node degree. Furthermore by puncturing the accumulators any desired high rate codes close to code rate 1 can be obtained with thresholds that stay close to the channel capacity thresholds uniformly. Iterative decoding simulation results are provided. The ARA codes also have projected graph or protograph representation that allows for high speed decoder implementation.

  6. Spatio-temporal course of macrophage-like cell accumulation after experimental embolic stroke depending on treatment with tissue plasminogen activator and its combination with hyperbaric oxygenation

    PubMed Central

    Michalski, D.; Heindl, M.; Kacza, J.; Laignel, F.; Küppers-Tiedt, L.; Schneider, D.; Grosche, J.; Boltze, J.; Löhr, M.; Hobohm, C.; Härtig, W.

    2012-01-01

    Inflammation following ischaemic stroke attracts high priority in current research, particularly using human-like models and long-term observation periods considering translational aspects. The present study aimed on the spatio-temporal course of macrophage-like cell accumulation after experimental thromboembolic stroke and addressed microglial and astroglial reactions in the ischaemic border zone. Further, effects of tissue plasminogen activator (tPA) as currently best treatment for stroke and the potentially neuroprotective co-administration of hyperbaric oxygen (HBO) were investigated. Rats underwent middle cerebral artery occlusion and were assigned to control, tPA or tPA+HBO. Twenty-four hours, 7, 14 and 28 days were determined as observation time points. The accumulation of macrophage-like cells was semiquantitatively assessed by CD68 staining in the ischaemic area and ischaemic border zone, and linked to the clinical course. CD11b, ionized calcium binding adaptor molecule 1 (Iba), glial fibrillary acidic protein (GFAP) and Neuronal Nuclei (NeuN) were applied to reveal delayed glial and neuronal alterations. In all groups, the accumulation of macrophage-like cells increased distinctly from 24 hours to 7 days post ischaemia. tPA+HBO tended to decrease macrophage-like cell accumulation at day 14 and 28. Overall, a trend towards an association of increased accumulation and pronounced reduction of the neurological deficit was found. Concerning delayed inflammatory reactions, an activation of microglia and astrocytes with co-occurring neuronal loss was observed on day 28. Thereby, astrogliosis was found circularly in contrast to microglial activation directly in the ischaemic area. This study supports previous data on long-lasting inflammatory processes following experimental stroke, and additionally provides region-specific details on glial reactions. The tendency towards a decreasing macrophage-like cell accumulation after tPA+HBO needs to be discussed

  7. Evidence for accumulation of Synechococcus elongatus (Cyanobacteria: Cyanophyceae) in the tissues of the oyster Crassostrea gigas (Mollusca: Bivalvia).

    PubMed

    Avila-Poveda, Omar Hernando; Torres-Ariño, Alejandra; Girón-Cruz, Diego Ademir; Cuevas-Aguirre, Angel

    2014-10-01

    Cyanobacteria appear to have direct relations with mollusks in several aspects. This is the first time, distinguishing Gram-negative cyanoprokaryotic Synechococcus elongatus as bright yellow-gold autofluorescence by Lillie's and Hiss' staining methods on paraffin-embedded tissues of Crassostrea gigas. Three diets: cyanoprokaryotes, cyanoprokaryotes with microalgae, and only microalgae were evaluated. Cyanoprokaryotes were intact, densely bundled, and immersed in the cytosol of the digestive gland, connective tissue, mantle, and gonad of C. gigas, revealing an accumulation systemic without tissue damage observed by histology. Unexpectedly, cyanoprokaryotes were slightly most accumulated with microalgae diet by each of the tissues of the C. gigas than with any other diets. Cyanoprokaryotes tend to be in mean slightly higher in the digestive gland than in any other tissues respectively for each diet, although these values are closely similar to connective tissue. A possible order of exposure of the oyster tissues to accumulation of cyanoprokaryotes was digestive gland, connective tissue, mantle, and gonad. Thereby, the digestive gland could be the major target tissue for the accumulation. Our observations provide a valuable insight regarding the ability of cyanoprokaryotes to penetrate, spread, and remain inside the oyster tissues, suggesting for S. elongatus: (1) a pre-accumulation in oyster tissues from the natural environment, (2) a phagocytosis and/or endocytosis process rather than ingestion and extracellular digestion, (3) an apparent cellular division in the cytosol of oyster tissues, (4) an apparent inter-tissue movement, and (5) a possible endosymbiosis between C. gigas and S. elongatus. Hereby, it is possible that S. elongatus have a well-developed host-endobiont relationship with oysters, and thereby support future work toward a description of the escape and spreading mechanisms of S. elongatus inside the tissues of mollusks, and put forward questions as

  8. Character, paleoenvironment, rate of accumulation, and evidence for seismic triggering of Holocene turbidites, Canada Abyssal Plain, Arctic Ocean

    USGS Publications Warehouse

    Grantz, A.; Phillips, R.L.; Mullen, M.W.; Starratt, S.W.; Jones, Glenn A.; Naidu, A.S.; Finney, B.P.

    1996-01-01

    Four box cores and one piston core show that Holocene sedimentation on the southern Canada Abyssal Plain for the last 8010??120 yr has consisted of a continuing rain of pelagic organic and ice-rafted elastic sediment with a net accumulation rate during the late Holocene of ???10 mm/1000 yr, and episodically emplaced turbidites 1-5 m thick deposited at intervals of 830 to 3450 yr (average 2000 yr). The average net accumulation rate of the mixed sequence of turbidites and thin pelagite interbeds in the cores is about 1.2 m/1000 yr. Physiography suggests that the turbidites originated on the Mackenzie Delta or its clinoform, and ??13C values of -27 to - 25??? in the turbidites are compatible with a provenance on a delta. Extant displaced neritic and lower slope to basin plain calcareous benthic foraminifers coexist in the turbidite units. Their joint occurence indicates that the turbidites originated on the modern continental shelf and entrained sediment from the slope and rise enroute to their final resting place on the Canada Abyssal Plain. The presence of Middle Pleistocene diatoms in the turbidites suggests, in addition, that the turbidites may have originated in shallow submarine slides beneath the upper slope or outer shelf. Small but consistent differences in organic carbon content and ??13C values between the turbidite units suggest that they did not share an identical provenance, which is at least compatible with an origin in slope failures. The primary provenance of the ice-rafted component of the pelagic beds was the glaciated terrane of northwestern Canada; and the provenance of the turbidite units was Pleistocene and Holocene sedimentary deposits on the outer continental shelf and upper slope of the Mackenzie Delta. Largely local derivation of the sediment of the Canada Abyssal Plain indicates that sediment accumulation rates in the Arctic Ocean are valid only for regions with similar depositional sources and processes, and that these rates cannot be

  9. Excess 210Po in 2010 Eyjafjallajökull tephra (Iceland): Evidence for pre-eruptive gas accumulation

    NASA Astrophysics Data System (ADS)

    Sigmarsson, Olgeir; Condomines, Michel; Gauthier, Pierre-Jean

    2015-10-01

    Excess gas phase in magmas erupting explosively is well known worldwide. However, the origin of this gas phase, in excess of what can be dissolved in the erupting magma at depth, and the rate of gas accumulation is less well defined. The 2010 mildly explosive eruption at Eyjafjallajökull, Iceland, produced mingled tephra of benmoreitic and trachytic composition whereas alkali basalt was emitted during preceding flank eruption. Tephra of the first explosive phase are composed of three glass types, alkaline rhyolite, mixed benmoreite, and basalt, which suggests that the basaltic magma intruded a pre-existing rhyolitic magma chamber, and ultimately triggered the eruption. The mixed benmoreitic tephra (erupted on 15 and 17 April 2010) had large 210Po in excess of 210Pb [(210Po /210Pb) 0 = 1.88 ] at the time of eruption, and possibly a small 210Pb excess over its parent 226Ra. In contrast, the preceding flank eruption produced basalt with (210Po) 0 = 0, upon eruption, and the final trachyte had lost most of its 210Po during open-system degassing. The 210Po excess in the first erupted benmoreites is interpreted to result from 210Po degassing of basaltic magma and the accumulation of 210Po-enriched gas, either in the upper part of the basaltic intrusion, below the rhyolite-basalt interface, or in the pre-existing residual rhyolitic magma chamber. From a simple model of radon and polonium accumulation in the rhyolitic reservoir, the ratio of the mass of basalt magma degassing over the mass of magma accumulating the excess gas decreased from 20 to 15 over 2 days, implying zoned magma reservoir, with the uppermost and gas-richest part erupting first. The duration of pre-eruptive gas accumulation in this model is approximately one year. This corresponds closely to the initiation of a seismic swarm beneath Eyjafjallajökull, early June 2009, which was the first pre-eruptive signal detected. The coincidence between initiation of gas accumulation at relatively shallow depth and

  10. Accumulation of PrP-Sc in hemal nodes of naturally and experimentally scrapie-infected sheep

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Classical scrapie is a naturally occurring fatal disease of sheep and goats which is caused by prions, a novel class of infectious agent. Infection is accompanied by accumulation of abnormal isoforms of the prion protein (PrP-Sc) in certain neural and lymphoid tissues. Hemal nodes, which are unique ...

  11. Demise of reef-flat carbonate accumulation with late Holocene sea-level fall: Evidence from Molokai, Hawaii

    USGS Publications Warehouse

    Engels, M.S.; Fletcher, C.H.; Field, M.; Conger, C.L.; Bochicchio, C.

    2008-01-01

    Twelve cores from the protected reef-flat of Molokai revealed that carbonate sediment accumulation, ranging from 3 mm year-1 to less than 1 mm year-1, ended on average 2,500 years ago. Modern sediment is present as a mobile surface veneer but is not trapped within the reef framework. This finding is consistent with the arrest of deposition at the end of the mid-Holocene highstand, known locally as the "Kapapa Stand of the Sea," ???2 m above the present datum ca. 3,500 years ago in the main Hawaiian Islands. Subsequent erosion, non-deposition, and/or a lack of rigid binding were probable factors leading to the lack of reef-flat accumulation during the late Holocene sea-level fall. Given anticipated climate changes, increased sedimentation of reef-flat environments is to be expected as a consequence of higher sea level. ?? 2008 Springer-Verlag.

  12. Experimental evidence for the K-LM radiative Auger effect in medium-mass atoms

    NASA Astrophysics Data System (ADS)

    Herren, Ch.; Dousse, J.-Cl.

    1997-10-01

    High-resolution measurements of the Kα1,2 low-energy satellites were performed for the elements 42Mo, 44Ru, 46Pd, 48Cd, and 50Sn. The photoinduced x-ray spectra were measured using a high-resolution transmission-type bent-crystal spectrometer in modified DuMond slit geometry. Experimental evidence for the K-LM radiative Auger effect (RAE) in solid medium-mass atoms was found and particular groups of the K-LM RAE transitions were identified. The experimental intensity ratios I(K-LM RAE) / I(Kα1,2) as well as the relative intensity of the K-L3M4,5 transition group were extracted from the measured spectra. A comparison of the experimental results with relativistic Hartree-Fock theoretical predictions from Scofield shows a good agreement. The experimental energies of the K-LM RAE edges are compared with calculated Auger transition energies.

  13. 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

  14. Experimental evidence of the superfocusing effect for axially channeled MeV protons

    NASA Astrophysics Data System (ADS)

    Motapothula, M.; Petrović, S.; Nešković, N.; Breese, M. B. H.

    2016-08-01

    Sub-Ångström focusing of megaelectronvolt (MeV) ions within axial channels was predicted over 10 years ago, but evidence proved elusive. We present experimental angular distributions of axially channeled MeV protons in a 55-nm-thick (001) silicon membrane through which multiple scattering is negligible. Fine angular structure is in excellent agreement with Monte Carlo simulations based on three interaction potentials, providing indirect evidence of the existence of the superfocusing effect with flux enhancement of around 800 within a focused beam width of ˜20 pm .

  15. 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.

  16. Impacts of zooplankton composition and algal enrichment on the accumulation of mercury in an experimental freshwater food web.

    PubMed

    Pickhardt, Paul C; Folt, Carol L; Chen, Celia Y; Klaue, Bjoern; Blum, Joel D

    2005-03-01

    There is a well documented accumulation of mercury in fish to concentrations of concern for human consumption. Variation in fish Hg burden between lakes is often high and may result from differences in Hg transfer through lower levels of the food web where mercury is bioconcentrated to phytoplankton and transferred to herbivorous zooplankton. Prior research derived patterns of mercury accumulation in freshwater invertebrates from field collected animals. This study provides results from controlled mesocosm experiments comparing the effects of zooplankton composition, algal abundance, and the chemical speciation of mercury on the ability of zooplankton to accumulate mercury from phytoplankton and transfer that mercury to planktivores. Experiments were conducted in 550-L mesocosms across a gradient of algal densities manipulated by inorganic nutrient additions. Enriched, stable isotopes of organic (CH3(200HgCl)) and inorganic (201HgCl2) mercury were added to mesocosms and their concentrations measured in water, seston, and three common zooplankton species. After 2 weeks, monomethylmercury (MMHg) concentrations were two to three times lower in the two copepod species, Leptodiaptomus minutus and Mesocyclops edax than in the cladoceran, Daphnia mendotae. All three zooplankton species had higher MMHg concentrations in mesocosms with low versus high initial algal abundance. However, despite higher concentrations of inorganic mercury (HgI) in seston from low nutrient mesocosms, there were no significant differences in the HgI accumulated by zooplankton across nutrient treatments. Bioaccumulation factors for MMHg in the plankton were similar to those calculated for plankton in natural lakes and a four-compartment (aqueous, seston, macrozooplankton, and periphyton/sediments) mass balance model after 21 days accounted for approximately 18% of the CH3(200Hg) and approximately 33% of the 201Hg added. Results from our experiments corroborate results from field studies and

  17. [Accumulation of the bvg- Bordetella pertussis a virulent mutants in the process of experimental whooping cough in mice].

    PubMed

    Medkova, A Iu; Siniashina, L N; Rumiantseva, Iu P; Voronina, O L; Kunda, M S; Karataev, G I

    2013-01-01

    The duration of the persistence and dynamics of accumulation of insertion bvg- Bordetella pertussis mutants were studied in lungs of laboratory mice after intranasal and intravenous challenge by virulent bacteria of the causative agent of whooping cough. The capability of the virulent B. pertussis bacteria to long-term persistence in the body of mice was tested. Using the real-time PCR approximately hundred genome equivalents of the B. pertussis DNA were detected in lungs of mice in two months after infection regardless of the way of challenge. Using the bacterial test bacteria were identified during only four weeks after challenge. Bvg- B. pertussis avirulent mutants were accumulated for the infection time. The percentage of the avirulent bacteria in the B. pertussis population reached 50% in 7-9 weeks after challenge. The obtained results show that the laboratory mice can be used for study of the B. pertussis insertion mutant formation dynamics in vivo and confirm the hypothesis about insertional bvg- B. pertussis virulent mutants accumulation during development of pertussis infection in human. PMID:24645274

  18. An experimental and theoretical evaluation of the influence of pretargeting antibody on the tumor accumulation of effector.

    PubMed

    Liu, Guozheng; Dou, Shuping; Rusckowski, Mary; Hnatowich, Donald J

    2008-05-01

    In treating tumors by pretargeting, the antitumor antibody and the cytotoxic effector (e.g., toxins and radioactivity) are separately administered. Therefore, pretargeting is more complicated with many variables. We are conducting studies to understand the influence of each variable using a novel recognition pair of mutually complementary phosphorodiamidate morpholino oligomers (MORF/cMORF). Earlier we developed a semi-empirical model capable of accurately predicting the behavior of a radiolabeled cMORF effector with variations in dosages and timing. We have now extended the model to predict the effector behavior, in particular, its maximum percent tumor accumulation (MPTA) in mice pretargeted with three different MORF-conjugated antibodies (MN14, B72.3, and CC49). The MN14 and the CC49 target different antigens in the same tumor, whereas the CC49 and the B72.3 target the same antigen but with very different tumor accumulation. By comparing the pretargeting results of these three antibodies with our prediction, we confirmed that the MPTA of the radiolabeled cMORF effector in the LS174T tumor is independent of the antibodies. In conclusion, the MPTA cannot be improved through the use of different pretargeting antibodies, although different antibodies may improve the maximum absolute tumor accumulation, the heterogeneity, and/or the tumor-to-normal tissue ratios of the effector. This conclusion will apply equally well to effectors carrying a fluorescent probe, an anticancer agent, or a radioactive imaging agent. PMID:18483292

  19. Conservation of arthropod midline netrin accumulation revealed with a cross-reactive antibody provides evidence for midline cell homology

    PubMed Central

    Simanton, Wendy; Clark, Stephanie; Clemons, Anthony; Jacowski, Caitlin; Farrell-VanZomeren, Adrienne; Beach, Paul; Browne, William E.; Duman-Scheel, Molly

    2009-01-01

    SUMMARY Although many similarities in arthropod CNS development exist, differences in axonogenesis and the formation of midline cells, which regulate axon growth, have been observed. For example, axon growth patterns in the ventral nerve cord of Artemia franciscana differ from that of Drosophila melanogaster. Despite such differences, conserved molecular marker expression at the midline of several arthropod species indicates that midline cells may be homologous in distantly related arthropods. However, data from additional species are needed to test this hypothesis. In this investigation, nerve cord formation and the putative homology of midline cells were examined in distantly related arthropods, including: long- and short-germ insects (D. melanogaster, Aedes aeygypti, and Tribolium castaneum), branchiopod crustaceans (A. franciscana and Triops longicauditus), and malacostracan crustaceans (Porcellio laevis and Parhyale hawaiensis). These comparative analyses were aided by a cross-reactive antibody generated against the Netrin (Net) protein, a midline cell marker and regulator of axonogenesis. The mechanism of nerve cord formation observed in Artemia is found in Triops, another branchiopod, but is not found in the other arthropods examined. Despite divergent mechanisms of midline cell formation and nerve cord development, Net accumulation is detected in a well-conserved subset of midline cells in branchiopod crustaceans, malacostracan crustaceans, and insects. Notably, the Net accumulation pattern is also conserved at the midline of the amphipod P. hawaiensis, which undergoes split germ-band development. Conserved Net accumulation patterns indicate that arthropod midline cells are homologous, and that Nets function to regulate commissure formation during CNS development of Tetraconata. PMID:19469853

  20. Accumulation of fructose 1,6-bisphosphate in mutant cells of mucoid Pseudomonas aeruginosa as an evidence of phosphofructokinase activity.

    PubMed

    Banerjee, P C

    1986-05-01

    Phosphoglucose isomerase negative mutant of mucoid Pseudomonas aeruginosa accumulated relatively higher concentration of fructose 1,6-bisphosphate (Fru-1,6-P2) when mannitol induced cells were incubated with this sugar alcohol. Also the toluene-treated cells of fructose 1,6-bisphosphate aldolase negative mutant of this organism produced Fru-1,6-P2 from fructose 6-phosphate in presence of ATP, but not from 6-phosphogluconate. The results together suggested the presence of an ATP-dependent fructose 6-phosphate kinase (EC 2.7.1.11) in mucoid P. aeruginosa. PMID:3017251

  1. 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. PMID:26683223

  2. 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.

  3. 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. PMID:25904671

  4. 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

  5. First evidence for accumulation of protein-bound and protein-free pyrraline in human uremic plasma by mass spectrometry.

    PubMed

    Odani, H; Shinzato, T; Matsumoto, Y; Takai, I; Nakai, S; Miwa, M; Iwayama, N; Amano, I; Maeda, K

    1996-07-01

    Glucose-derived advanced glycation end products (AGEs) cross-link proteins and cause various biological tissue damage. One of them, pyrraline [epsilon-2-(formyl-5-hydroxymethyl-pyrrol-1-yl) -L-norleucine], has been demonstrated by utilizing antibody to accumulate in plasma and sclerosed matrix of diabetic individuals, suggesting responsibility for diabetic complications. To elucidate the involvement of pyrraline in uremia, we examined the pyrraline levels in patients with chronic renal failure by a mass spectrometric approach. Here we show that protein-free pyrraline as well as pyrraline with binding protein are significantly increased in non-diabetic uremic plasma compared to healthy subjects. Our results suggest that circulating pyrraline could be a substance contributing to complications in uremia. PMID:8694819

  6. Crustal strain accumulation on Southern Basin and Range Province faults modulated by distant plate boundary earthquakes? Evidence from geodesy, seismic imaging, and paleoseismology

    NASA Astrophysics Data System (ADS)

    Bennett, R. A.; Shirzaei, M.; Broermann, J.; Spinler, J. C.; Holland, A. A.; Pearthree, P.

    2014-12-01

    GPS in Arizona reveals a change in the pattern of crustal strain accumulation in 2010 and based on viscoelastic modeling appears to be associated with the distant M7.2 El Mayor-Cucapah (EMC) earthquake in Baja California, Mexico. GPS data collected between 1999 and 2009 near the Santa Rita normal fault in SE Arizona reveal a narrow zone of crustal deformation coincident with the fault trace, delineated by W-NW facing Pleistocene fault scarps of heights 1 to 7 m. The apparent deformation zone is also seen in a preliminary InSAR interferogram. Total motion across the zone inferred using an elastic block model constrained by the pre-2010 GPS measurements is ~1 mm/yr in a sense consistent with normal fault motion. However, continuous GPS measurements throughout Arizona reveal pronounced changes in crustal velocity following the EMC earthquake, such that the relative motion across the Santa Rita fault post-2010 is negligible. Paleoseismic evidence indicates that mapped Santa Rita fault scarps were formed by two or more large magnitude (M6.7 to M7.6) surface rupturing normal-faulting earthquakes 60 to 100 kyrs ago. Seismic refraction and reflection data constrained by deep (~800 m) well log data provide evidence of progressive, possibly intermittent, displacement on the fault through time. The rate of strain accumulation observed geodetically prior to 2010, if constant over the past 60 to 100 kyrs, would imply an untenable minimum slip rate deficit of 60 to 100 m since the most recent earthquake. One explanation for the available geodetic, seismic, and paleoseismic evidence is that strain accumulation is modulated by viscoelastic relaxation associated with frequent large magnitude earthquakes in the Salton Trough region, episodically inhibiting the accumulation of elastic strain required to generate large earthquakes on the Santa Rita and possibly other faults in the Southern Basin and Range. An important question is thus for how long the postseismic velocity changes

  7. Reduction of zinc accumulation in mitochondria contributes to decreased cerebral ischemic injury by normobaric hyperoxia treatment in an experimental stroke model.

    PubMed

    Dong, Wen; Qi, Zhifeng; Liang, Jia; Shi, Wenjuan; Zhao, Yongmei; Luo, Yumin; Ji, Xunming; Liu, Ke Jian

    2015-10-01

    Cerebral ischemia interrupts oxygen supply to the affected tissues. Our previous studies have reported that normobaric hyperoxia (NBO) can maintain interstitial partial pressure of oxygen (pO2) in the penumbra of ischemic stroke rats at the physiological level, thus affording significant neuroprotection. However, the mechanisms that are responsible for the penumbra rescue by NBO treatment are not fully understood. Recent studies have shown that zinc, an important mediator of intracellular and intercellular neuronal signaling, accumulates in neurons and leads to ischemic neuronal injury. In this study, we investigate whether NBO could regulate zinc accumulation in the penumbra and prevent mitochondrial damage in penumbral tissue using a transient cerebral ischemic rat model. Our results showed that NBO significantly reduced zinc-staining positive cells and zinc-staining intensity in penumbral tissues, but not in the ischemic core. Moreover, ischemia-induced zinc accumulation in mitochondria, isolated from penumbral tissues, was greatly attenuated by NBO or a zinc-specific chelator, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN). NBO or TPEN administration stabilized the mitochondrial membrane potential in the penumbra after cerebral ischemia. Finally, ischemia-induced cytochrome c release from mitochondria in penumbral tissues was significantly reduced by NBO or TPEN treatment. These findings demonstrate a novel mechanism for NBO's neuroprotection, especially to penumbral tissues, providing further evidence for the potential clinical benefit of NBO for acute ischemic stroke. PMID:25891441

  8. An Extraordinary Accumulation of (-)-Pinoresinol in Cell-Free Extracts of Forsythia intermedia: Evidence for Enantiospecific Reduction of (+)-Pinoresinol

    NASA Technical Reports Server (NTRS)

    Katayama, Takeshi; Davin, Laurence B.; Lewis, Norman G.

    1992-01-01

    Stereoselective and enantiospecific transformation mechanisms in lignan biogenesis are only now yielding to scientific inquiry: it has been shown that soluble cell-free preparations from Forsythia intermedia catalysis the formation of the enantiomerically pure lignan, (-)-secoisolariciresinol, when incubated with coniferyl alcohol in the presence of NAD(P)H and H2O2. Surprisingly, (-)-pinoresinol also accumulates in this soluble cell-free assay mixture in greater than 96% enantiomeric excess, even though it is not the naturally occurring antipode present in Forsythia sp. But these soluble cell-free preparations do not engender stereoselective coupling; instead, racemic pinoresinols are first formed, catalysed by an H2O2-dependent peroxidase reaction. An enantiospecific NAD(P)H reductase then converts (+)- pinoresinol, and not the (-)-antipode, into (-)-secoisolariciresinol. Stereoselective syntheis of(+)-pinoresinol from E-coniferyl alcohol is, however, catalysed by an insoluble enzyme preparation in F. suspensa, obtained following removal of readily soluble and ionically bound enzymes; no exogenously supplied cofactors were required other than oxygen, although the reaction was stimulated by NAD-malate addition. Thus, the overall biochemical pathway to enantiomerically pure (-)-secoisolariciresinol has been delineated.

  9. Temporal trends of triclosan contamination in dated sediment cores from four urbanized estuaries: evidence of preservation and accumulation.

    PubMed

    Cantwell, Mark G; Wilson, Brittan A; Zhu, Jun; Wallace, Gordon T; King, John W; Olsen, Curtis R; Burgess, Robert M; Smith, Joseph P

    2010-01-01

    Triclosan is an antimicrobial agent added to a wide array of consumer goods and personal care products. Through its use, it is introduced into municipal sewer systems where it is only partially removed during wastewater treatment. In this study, triclosan was measured in dated sediment cores from four urbanized estuaries in order to reconstruct temporal and spatial trends of accumulation. Measurable concentrations of triclosan first appeared in each of the sediment cores near 1964, which corresponds with the US patent issuance date of triclosan. The presence of triclosan at each of the study sites at or near the patent date indicates that long-term preservation is occurring in estuarine sediments. Temporal trends of triclosan at each location are unique, reflecting between site variability. Concentrations at one site climbed to as high as 400ngg(-1), due in part, to local commercial production of triclosan. At two locations, levels of triclosan rise towards the surface of each core, suggesting increasing usage in recent years. One location adjacent to a major combined sewer overflow had high sediment concentrations of triclosan, confirming their potential as a source of triclosan to estuaries. PMID:20006371

  10. Experimental evidence for the acceleration of thermal electrons by ion cyclotron waves in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Norris, A. J.; Sojka, J. J.; Wrenn, G. L.; Johnson, J. F. E.; Cornilleau-Wehrlin, N.; Perraut, S.; Roux, A.

    1983-01-01

    Experimental evidence is presented for the acceleration of thermal electrons by large amplitude ion cyclotron waves (ICWs). The wave power in the ULF range near the helium gyrofrequency is compared with the distribution function of low energy electrons measured by GEOS satellite instruments. This comparison shows that electrons are accelerated near the geomagnetic equator along field lines, at times when the ICW energy is large and the cold plasma density is below a threshold value. It is suggested that these accelerated electrons can account for the ELF emissions, modulated at the ICW frequency, observed by Wehrlin (1981). A very efficient acceleration of thermal electrons along field lines results from other ULF events having frequencies close to the proton gyrofrequency. Evidence for this lies in the fact that medium energy protons having large temperature anisotropies in the 100-500 eV range are responsible for the ICW wave generation.

  11. Rapid and frequent turbidite accumulation in the bottom of Izu-Ogasawara Trench: Chemical and radiochemical evidence

    NASA Astrophysics Data System (ADS)

    Nozaki, Yoshiyuki; Ohta, Yoichi

    1993-12-01

    Two sediment cores (pilot gravity and piston) were obtained from the bottom of the Izu-Ogasawara Trench at 9750 m and analyzed for various elements and radioisotopes. The results showed a history of complex and frequent turbidite deposition: In the gravity core, eight layers rich in manganese were observed, of which five are enriched in Cu and Co as well. The other three are also enriched in Mo but no other heavy metals, suggesting the presence of at least two mechanisms of formation. Trapping of iron manganese micronodules can account for the enrichment of Mn, Cu and Co. The other three layers rich in Mn and Mo appear to be formed by a post-depositional diagenetic process of Mn mobilization and redeposition in the sediment column. A strong correlation between Ra-226 and Cu in the gravity core suggests that the Ra-226 was also carried into the bottom of the trench in turbidites in association with Mn micronodules. Little excess of Pb-210 over Ra-226 was found at the top but the excess was significant at mid-depths from 30 to 70 cm, indicating that those sediments were deposited within the last 200 y. In the piston core there is a sharp discontinuity of chemical and radiochemical composition around a depth of 250 cm. Below that depth the sediments appear to be dominated by materials derived from terrestrial sources, as compared with those in the upper layer which are of contemporary marine origin. Ra-226 is deficient relative to Th-230 throughout the sediment column down to about 6 m. This finding is consistent with the finding that the average rate of sediment accumulation is 1-2 orders of magnitude faster than that in the western North Pacific abyssal plain, suggesting the convergence of materials into the bottom of the trench.

  12. The effect of experimentally-induced renal failure on accumulation of bupropion and its major basic metabolites in plasma and brain of guinea pigs.

    PubMed

    DeVane, C L; Laizure, S C; Cameron, D F

    1986-01-01

    Dosage regimen adjustments because of poor renal function are often assumed to be unnecessary for extensively metabolized antidepressants. This assumption is being increasingly questioned in recognition of the role of active drug metabolites. The purpose of this study was to assess the steady-state accumulation of the new antidepressant bupropion and its three major basic metabolites in guinea pigs, with and without experimentally-induced renal failure. Two groups of guinea pigs were treated by intraperitoneal (IP) implantation of mini-osmotic pumps containing bupropion hydrochloride. Immediately after surgery, one group of animals received an injection of uranyl nitrate. After 4 days, all animals were sacrificed by decapitation following blood removal by cardiac puncture. Analysis of plasma and brain samples by high performance liquid chromatography (HPLC) for concentrations of bupropion (BUP) and its major basic metabolites, the erythro-amino alcohol (EB), the threo-amino alcohol (TB) and the hydroxy metabolite (HB) revealed greater accumulation of BUP, TB, and HB in plasma and brain of the animals with renal failure compared to controls. No difference was found between groups in the concentrations of the EB metabolite. As the guinea pig shows a BUP and metabolite plasma concentration profile similar to that seen in human studies, these results suggest that further studies of bupropion and its major metabolites are warranted in patients with impaired renal function to assess possible excessive drug and metabolite accumulation. PMID:3092270

  13. Experimental evidence for the stability of the depletion zone around a growing protein crystal under microgravity.

    PubMed

    Otálora, F; Novella, M L; Gavira, J A; Thomas, B R; García Ruiz, J M

    2001-03-01

    Experimental evidence is presented for the first time for the development and time evolution of concentration-depletion zones around protein crystals growing in microgravity and gelled on-ground experiments. Crystal motion and buoyancy-driven fluid movements as a result of residual accelerations and g-jitters are demonstrated to have an adverse effect on the stability of these depletion zones, provoking the breakdown of their radial symmetry. These findings may explain some of the controversial results reported on the quality of single crystals grown under microgravity in previous space missions. PMID:11223518

  14. Experimental evidence of Ga-vacancy induced room temperature ferromagnetic behavior in GaN films

    SciTech Connect

    Roul, Basanta; Kumar, Mahesh; Rajpalke, Mohana K.; Bhat, Thirumaleshwara N.; Krupanidhi, S. B.; Kalghatgi, A. T.; Kumar, Nitesh; Sundaresan, A.

    2011-10-17

    We have grown Ga deficient GaN epitaxial films on (0001) sapphire substrate by plasma-assisted molecular beam epitaxy and report the experimental evidence of room temperature ferromagnetic behavior. The observed yellow emission peak in room temperature photoluminescence spectra and the peak positioning at 300 cm{sup -1} in Raman spectra confirms the existence of Ga vacancies. The x-ray photoelectron spectroscopic measurements further confirmed the formation of Ga vacancies; since the N/Ga is found to be >1. The ferromagnetism is believed to originate from the polarization of the unpaired 2p electrons of N surrounding the Ga vacancy.

  15. In vivo (/sup 3/H)spiperone binding: evidence for accumulation in corpus striatum by agonist-mediated receptor internalization

    SciTech Connect

    Chugani, D.C.; Ackermann, R.F.; Phelps, M.E.

    1988-06-01

    The processes of receptor internalization and recycling have been well-documented for receptors for hormones, growth factors, lysosomal enzymes, and cellular substrates. Evidence also exists that these processes also occur for beta-adrenergic, muscarinic cholinergic, and delta-opiate receptors in frog erythrocytes or cultured nervous tissue. In this study, evidence is presented that agonist-mediated receptor internalization and recycling occurs at the dopamine receptor in rat corpus striatum. First, the in vivo binding of the dopamine antagonist (3H)spiperone was increased by both electrical stimulation and pharmacologically induced increases of dopamine release. Conversely, depletion of dopamine with reserpine decreased in vivo (3H)spiperone binding, but the same reserpine treatment did not alter its in vitro binding. Second, the rate of dissociation of (3H)spiperone from microsomal membranes prepared from rat striatum following in vivo binding was fivefold slower than its dissociation following in vitro equilibrium binding. Mild detergent treatment, employed to disrupt endocytic vesicle membranes, increased the rate of dissociation of in vivo bound (3H)spiperone from microsomal membranes to values not significantly different from its in vitro bound dissociation rate. Third, treatment of rats with chloroquine, a drug that prevents receptor recycling but not internalization, prior to (3H)spiperone injection resulted in a selective increase of in vivo (3H)spiperone binding in the light microsome membranes. The existence of mechanisms that rapidly alter the number of neurotransmitter receptors at synapses provides dynamic regulation of receptors in response to varied acute stimulation states.

  16. 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

  17. Experimental evidence for chirality in the odd-A 105Rh

    NASA Astrophysics Data System (ADS)

    Timár, J.; Joshi, P.; Starosta, K.; Dimitrov, V. I.; Fossan, D. B.; Molnár, J.; Sohler, D.; Wadsworth, R.; Algora, A.; Bednarczyk, P.; Curien, D.; Dombrádi, Zs.; Duchene, G.; Gizon, A.; Gizon, J.; Jenkins, D. G.; Koike, T.; Krasznahorkay, A.; Paul, E. S.; Raddon, P. M.; Rainovski, G.; Scheurer, J. N.; Simons, A. J.; Vaman, C.; Wilkinson, A. R.; Zolnai, L.; Frauendorf, S.

    2004-09-01

    High-spin states in 105Rh were populated by the 96Zr(13C, p3n) reaction at beam energies of 51 and 58 MeV, and studied using the EUROBALL IV γ-ray spectrometer and the DIAMANT charged particle array. A pair of nearly degenerate ΔI = 1 three-quasiparticle bands with the same spins and parity have been observed. Comparison of the experimental results with tilted axis cranking calculations confirms the chiral character of the two bands, while arguments based on the excitation of particles within the πg9 / 2 ν(h11 / 2) 2 configuration of the yrast band and comparison with the previously observed γ band exclude the other possible interpretations. This is the first experimental evidence for three-quasiparticle chiral structure in the A ∼ 100 region, and the first simultaneous observation of a γ band and chiral partner bands in one nucleus.

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

    PubMed

    Holman, Luke; Head, Megan L; Lanfear, Robert; Jennions, Michael D

    2015-07-01

    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

  19. 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. PMID:27128070

  20. Experimental evidence of deterministic coherence resonance in coupled chaotic systems with frequency mismatch

    NASA Astrophysics Data System (ADS)

    García-Vellisca, M. A.; Pisarchik, A. N.; Jaimes-Reátegui, R.

    2016-07-01

    We present the experimental evidence of deterministic coherence resonance in unidirectionally coupled two and three Rössler electronic oscillators with mismatch between their natural frequencies. The regularity in both the amplitude and the phase of chaotic fluctuations is experimentally proven by the analyses of normalized standard deviations of the peak amplitude and interpeak interval and Lyapunov exponents. The resonant chaos suppression appears when the coupling strength is increased and the oscillators are in phase synchronization. In two coupled oscillators, the coherence enhancement is associated with negative third and fourth Lyapunov exponents, while the largest first and second exponents remain positive. Distinctly, in three oscillators coupled in a ring, all exponents become negative, giving rise to periodicity. Numerical simulations are in good agreement with the experiments.

  1. Experimental and theoretical evidence for an ionic crystal of ammonia at high pressure

    NASA Astrophysics Data System (ADS)

    Ninet, S.; Datchi, F.; Dumas, P.; Mezouar, M.; Garbarino, G.; Mafety, A.; Pickard, C. J.; Needs, R. J.; Saitta, A. M.

    2014-05-01

    We report experimental and theoretical evidence that solid molecular ammonia becomes unstable at room temperature and high pressures and transforms into an ionic crystalline form. This material has been characterized in both hydrogenated (NH3) and deuterated (ND3) ammonia samples up to about 180 and 200 GPa, respectively, by infrared absorption, Raman spectroscopy, and x-ray diffraction. The presence of a new strong infrared absorption band centered at 2500 cm-1 in NH3 (1900 cm-1 in ND3) is in line with previous theoretical predictions regarding the ionization of ammonia molecules into NH2- and NH4+ ions. The experimental data suggest the coexistence of two crystalline ionic forms, which our ab initio structure searches predict to be the most stable at the relevant pressures. The ionic crystalline form of ammonia appears stable at low temperatures, which contrasts with the behavior of water in which no equivalent crystalline ionic phase has been found.

  2. 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. PMID:26809142

  3. 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.

  4. Properties of Modern Dust Accumulating in the Uinta Mountains, Utah, USA, and Soil Evidence of Long-Term Dust Deposition

    NASA Astrophysics Data System (ADS)

    Munroe, J. S.

    2013-12-01

    Modern eolian sediment was collected at four locations in the alpine zone of the Uinta Mountains (Utah, USA) between July 2011 and July 2012. Collectors were a passive design based on the classic marble dust trap, but modified for use in this high-precipitation environment. On average the collectors accumulated 1.5 gm of dust, corresponding to an annual flux of 4.4 g/m2. This result is similar to values measured from snowpack samples in the Wind River (Wyoming) and San Juan (Colorado) Mountains. Dust flux was 3 to 5x higher during the winter compared with summer at the two sites featuring continuous vegetation, but was consistent between the seasons at the two collectors surrounded by a greater area of exposed soil. XRD analysis reveals that dust samples are dominated by quartz, potassium feldspar, plagioclase, and illite. Some samples contain amphibole and chlorite. In contrast, samples of fine sediment collected from the surface of modern snowbanks are dominated by clay with no feldspar or quartz, suggesting that these minerals are derived from the surrounding soil surface, which is snow-covered in the winter. ICP-MS analysis reveals that the geochemistry of the coarse (>63-μm) fraction of the dust resembles that of the underlying bedrock, confirming a local origin for this sediment. In contrast, the fine (<63-μm) fraction of the dust closely matches the fine fraction of the soil A horizon, supporting an eolian origin for the ubiquitous layer of fines that mantles soil profiles throughout the Uinta Mountains. Grain size analysis with laser scattering reveals that modern dust is very well-sorted, with a median size of 8 μm (7.0 Φ). Using the annual dust flux and mean grain size, and taking into account the measured bulk density (0.95 gm/cm3), organic matter content (20%), and silt content (32%) of this loess cap, the extrapolated loess accretion rate is ~18 cm per 10,000 years. Given that prior studies (Bockheim et al., 2000 Catena; Munroe, 2007, Arctic

  5. Experimental evidence that brighter males sire more extra-pair young in tree swallows.

    PubMed

    Whittingham, Linda A; Dunn, Peter O

    2016-08-01

    Across taxa, extra-pair mating is widespread among socially monogamous species, but few studies have identified male ornamental traits associated with extra-pair mating success, and even fewer studies have experimentally manipulated male traits to determine whether they are related directly to paternity. As a consequence, there is little experimental evidence to support the widespread hypothesis that females choose more ornamented males as extra-pair mates. Here, we conducted an experimental study of the relationship between male plumage colour and fertilization success in tree swallows (Tachycineta bicolor), which have one of the highest levels of extra-pair mating in birds. In this study, we experimentally dulled the bright blue plumage on the back of males (with nontoxic ink markers) early in the breeding season prior to most mating. Compared with control males, dulled males sired fewer extra-pair young, and, as a result, fewer young overall. Among untreated males, brighter blue males also sired more extra-pair young, and in paired comparisons, extra-pair sires had brighter blue plumage than the within-pair male they cuckolded. These results, together with previous work on tree swallows, suggest that extra-pair mating behaviour is driven by benefits to both males and females. PMID:27105297

  6. 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. PMID:27009222

  7. Evidence of liquid phase during laser-induced periodic surface structures formation induced by accumulative ultraviolet picosecond laser beam

    SciTech Connect

    Huynh, T. T. D.; Petit, A.; Semmar, N.

    2015-11-09

    Laser-induced periodic surface structures (LIPSS) were formed on Cu/Si or Cu/glass thin films using Nd:YAG laser beam (40 ps, 10 Hz, and 30 mJ/cm{sup 2}). The study of ablation threshold is always achieved over melting when the variation of the number of pulses increases from 1 to 1000. But the incubation effect is leading to reduce the threshold of melting as increasing the number of laser pulse. Also, real time reflectivity signals exhibit typical behavior to stress the formation of a liquid phase during the laser-processing regime and helps to determine the threshold of soft ablation. Atomic Force Microscopy (AFM) analyses have shown the topology of the micro-crater containing regular spikes with different height. Transmission Electron Microscopy (TEM) allows finally to show three distinguished zones in the close region of isolated protrusions. The central zone is a typical crystallized area of few nanometers surrounded by a mixed poly-crystalline and amorphous area. Finally, in the region far from the protrusion zone, Cu film shows an amorphous structure. The real time reflectivity, AFM, and HR-TEM analyses evidence the formation of a liquid phase during the LIPSS formation in the picosecond regime.

  8. Synchrotron FTIR shows evidence of DNA damage and lipid accumulation in prostate adenocarcinoma PC-3 cells following proton irradiation

    NASA Astrophysics Data System (ADS)

    Lipiec, Ewelina; Bambery, Keith R.; Heraud, Phil; Hirschmugl, Carol; Lekki, Janusz; Kwiatek, Wojciech M.; Tobin, Mark J.; Vogel, Christian; Whelan, Donna; Wood, Bayden R.

    2014-09-01

    Synchrotron Radiation Fourier Transform Infrared (SR-FTIR) spectra of single human prostate adenocarcinoma PC-3 cells, irradiated with a defined number of 2 MeV protons generated by a proton microbeam along with non-irradiated control cells, were analysed using multivariate methods. A number of different Principal Component Analysis (PCA) models were tested and the spectral ranges associated with nucleic acids, proteins and lipids were analysed separately. The results show a dose dependent shift of the Osbnd Psbnd O asymmetric stretching mode from 1234 cm-1 to 1237 cm-1, consistent with local disorder in the B-DNA conformation along with a change in intensity of the Osbnd Psbnd O symmetric stretching band at 1083 cm-1 indicative of chromatin fragmentation - the natural consequence of a high number of DNA Double Strand Breaks (DSBs). 2D mapping of characteristic functional groups at the diffraction limit shows evidence of lipid deposition and chromatin condensation in cells exposed to protons indicative of cell apoptosis following irradiation. These studies lay the foundation for understanding the macromolecular changes that occur to cells in response to radiation therapy, which has important implications in the treatment of tumours.

  9. [Significance of Tc-99m pyrophosphate accumulation in unstable angina: clinical characteristics and evidence for myocardial stunning].

    PubMed

    Tange, S; Kondo, C; Ohta, Y; Kusakabe, K; Shigeta, A; Uchida, T; Sumiyoshi, T; Kaneko, N; Hosoda, S

    1993-01-01

    Tc-99m pyrophosphate (PYP) and Tl-201 simultaneous dual energy single photon emission computed tomography (SPECT) were performed for 33 patients with clinically diagnosed unstable angina. Twenty-two patients (76%) showed PYP accumulation in the myocardium (PYP+group). Clinical features, types of unstable angina, electrocardiographic changes during and after the anginal attack, and serial creatine kinase (CK) sampling data were reviewed and compared in the 2 groups. Selective coronary angiography was performed in all patients, and contrast left ventriculography was carried out in 29 patients both in unstable and stable states. In the study of left ventriculograms, the ejection fraction (EF) was calculated by the area-length method and the wall motion abnormality index was calculated by the centerline method. The PYP(+)group differed significantly from the PYP(-)group in several features as follows: 1) the "new angina at rest" type of unstable angina was more frequent in the PYP(+)group than in the PYP(-)group. The ratios of new angina at rest/effort angina (including new angina of effort and angina of effort with changing pattern) were 16/6; 2/9 for the PYP(+) and (-)groups, respectively (p < 0.05). 2) ST elevation during the heart attack was seen more in the PYP(+)group. The ratios of ST elevation/ST depression were 13/22 (59%); 5/22 (23%) for the PYP(+)group, and 2/11 (18%); 7/11 (64%) for the PYP(-)group, respectively (p < 0.05). 3) EF was improved in the PYP(+) group to the normal range. EF in the PYP(+)group changed from 57 +/- 12 in the unstable state to 62 +/- 11% in the stable state (p < 0.02), while that of the PYP(-)group showed no significant difference between the unstable state (59 +/- 9%) and the stable state (59 +/- 11%). 4) Wall motion abnormality index (WMI) in the PYP(+)group was poorer than in the PYP(-)group, but it improved markedly in one month to the same level as that of the PYP(-)group. WMI in the PYP(+)group in the unstable state (21

  10. Experimental evidence for a liquid-liquid crossover in deeply cooled confined water.

    PubMed

    Cupane, Antonio; Fomina, Margarita; Piazza, Irina; Peters, Judith; Schirò, Giorgio

    2014-11-21

    In this work we investigate, by means of elastic neutron scattering, the pressure dependence of mean square displacements (MSD) of hydrogen atoms of deeply cooled water confined in the pores of a three-dimensional disordered SiO2 xerogel; experiments have been performed at 250 and 210 K from atmospheric pressure to 1200 bar. The "pressure anomaly" of supercooled water (i.e., a mean square displacement increase with increasing pressure) is observed in our sample at both temperatures; however, contrary to previous simulation results and to the experimental trend observed in bulk water, the pressure effect is smaller at lower (210 K) than at higher (250 K) temperature. Elastic neutron scattering results are complemented by differential scanning calorimetry data that put in evidence, besides the glass transition at about 170 K, a first-order-like endothermic transition occurring at about 230 K that, in view of the neutron scattering results, can be attributed to a liquid-liquid crossover. Our results give experimental evidence for the presence, in deeply cooled confined water, of a crossover occurring at about 230 K (at ambient pressure) from a liquid phase predominant at 210 K to another liquid phase predominant at 250 K; therefore, they are fully consistent with the liquid-liquid transition hypothesis. PMID:25479506

  11. 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. PMID:26545246

  12. Ultrastructural evidence for the accumulation of insulin in nuclei of intact 3T3-L1 adipocytes by an insulin-receptor mediated process

    SciTech Connect

    Smith, R.M.; Jarett, L.

    1987-01-01

    Monomeric ferritin-labeled insulin (F/sub m/-Ins), a biologically active, electron-dense marker of occupied insulin receptors, was used to characterize the internalization of insulin in 3T3-L1 adipocytes. F/sub m/-Ins bound specifically to insulin receptors and was internalized in a time- and temperature-dependent manner. In the nucleus, several F/sub m/-Ins particles usually were found in the same general location-near nuclear pores, associated with the periphery of the condensed chromatin. Addition of a 250-fold excess of unlabeled insulin or incubation at 15/sup 0/C reduced the number of F/sub m/-Ins particles found in nuclei after 90 min by 99% or 92%, respectively. Nuclear accumulation of unlabeled ferritin was only 2% of that found with F/sub m/-Ins after 90 min at 37/sup 0/C. Biochemical experiments utilizing /sup 125/I-labeled insulin and subcellular fractionation indicated that intact 3T3-L1 adipocytes internalized insulin rapidly and that approx. = 3% of the internalized ligand accumulated in nuclei after 1 hr. These data provide biochemical and high-resolution ultrastructural evidence that 3T3-L1 adipocytes accumulate potentially significant amounts of insulin in nuclei by an insulin receptor-mediated process. The transport of insulin or the insulin-receptor complex to nuclei in this cell or in others may be directly involved in the long-term biological effects of insulin - in particular, in the control of DNA and RNA synthesis.

  13. Accumulate-Repeat-Accumulate-Accumulate-Codes

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush; Dolinar, Sam; Thorpe, Jeremy

    2004-01-01

    Inspired by recently proposed Accumulate-Repeat-Accumulate (ARA) codes [15], in this paper we propose a channel coding scheme called Accumulate-Repeat-Accumulate-Accumulate (ARAA) codes. These codes can be seen as serial turbo-like codes or as a subclass of Low Density Parity Check (LDPC) codes, and they have a projected graph or protograph representation; this allows for a high-speed iterative decoder implementation using belief propagation. An ARAA code can be viewed as a precoded Repeat-and-Accumulate (RA) code with puncturing in concatenation with another accumulator, where simply an accumulator is chosen as the precoder; thus ARAA codes have a very fast encoder structure. Using density evolution on their associated protographs, we find examples of rate-lJ2 ARAA codes with maximum variable node degree 4 for which a minimum bit-SNR as low as 0.21 dB from the channel capacity limit can be achieved as the block size goes to infinity. Such a low threshold cannot be achieved by RA or Irregular RA (IRA) or unstructured irregular LDPC codes with the same constraint on the maximum variable node degree. Furthermore by puncturing the accumulators we can construct families of higher rate ARAA codes with thresholds that stay close to their respective channel capacity thresholds uniformly. Iterative decoding simulation results show comparable performance with the best-known LDPC codes but with very low error floor even at moderate block sizes.

  14. Evidence of self organization in great Sumatra earthquake recurrence times: Implications for coupling of tidal forcing and tectonic stress accumulation

    NASA Astrophysics Data System (ADS)

    Tiwari, R. K.; Puli, K.

    2012-12-01

    We analyzed inter- event time series of earthquake activities (M≥ 5) of Sumatra region spanning over 1973 to 2009 using techniques of nonlinear dynamics. The earthquake data were taken from the USGS catalogue centered on latitude 3.240N and longitude 95.825E. As a first step, in our analyses we computed the rank order statistics which revealed mixed response of earthquake dynamics indicating distinct breaks in slope of the rank order. This suggests that earthquake dynamics in this region is partly unstable and partly "self-organized" with a random tail. Comparison of return maps of the earthquakes inter- event time series with those representing random, stochastic and chaotic processes shows a quasi-deterministic behavior of earthquake genesis in the region. We further assessed the dimensionality of earthquake-generating mechanisms using a nonlinear predictor technique on two dimensional phase portrait constructed by recurrence time series. The nonlinear forecasting analysis suggests that the earthquake processes in the Sumatra region evolve on a non-random low-dimensional chaotic plane. Further, "K2" Entropy revealed a coherent structure indicating the deterministic dynamical pattern. This analysis is consistent with "self-organized" processes which could be explained invoking earth's internal dynamics, where, impulsively derived interdependencies cascades through the stress generated by tectonic plate movement. Our results, however, do not preclude the role of coupling of the above self-organized system with tidal forcing. Evidence for such a coupling in this region exists as 'triggering force". Keywords: Sumatra Earthquakes, Quasi-deterministic, Stochastic, Chaotic, Self-organized, K2 entropy, Phase portrait.

  15. Evidence of Cholesterol Accumulated in High Curvature Regions: Implication to the Curvature Elastic Energy for Lipid Mixtures

    PubMed Central

    Wang, Wangchen; Yang, Lin; Huang, Huey W.

    2007-01-01

    Recent experiments suggested that cholesterol and other lipid components of high negative spontaneous curvature facilitate membrane fusion. This is taken as evidence supporting the stalk-pore model of membrane fusion in which the lipid bilayers go through intermediate structures of high curvature. How do the high-curvature lipid components lower the free energy of the curved structure? Do the high-curvature lipid components modify the average spontaneous curvature of the relevant monolayer, thereby facilitate its bending, or do the lipid components redistribute in the curved structure so as to lower the free energy? This question is fundamental to the curvature elastic energy for lipid mixtures. Here we investigate the lipid distribution in a monolayer of a binary lipid mixture before and after bending, or more precisely in the lamellar, hexagonal, and distorted hexagonal phases. The lipid mixture is composed of 2:1 ratio of brominated di18:0PC and cholesterol. Using a newly developed procedure for the multiwavelength anomalous diffraction method, we are able to isolate the bromine distribution and reconstruct the electron density distribution of the lipid mixture in the three phases. We found that the lipid distribution is homogenous and uniform in the lamellar and hexagonal phases. But in the distorted hexagonal phase, the lipid monolayer has nonuniform curvature, and cholesterol almost entirely concentrates in the high curvature region. This finding demonstrates that the association energies between lipid molecules vary with the curvature of membrane. Thus, lipid components in a mixture may redistribute under conditions of nonuniform curvature, such as in the stalk structure. In such cases, the spontaneous curvature depends on the local lipid composition and the free energy minimum is determined by lipid distribution as well as curvature. PMID:17259270

  16. Nitrogen starvation-induced accumulation of triacylglycerol in the green algae: evidence for a role for ROC40, a transcription factor involved in circadian rhythm.

    PubMed

    Goncalves, Elton C; Koh, Jin; Zhu, Ning; Yoo, Mi-Jeong; Chen, Sixue; Matsuo, Takuya; Johnson, Jodie V; Rathinasabapathi, Bala

    2016-03-01

    Microalgal triacylglycerol (TAG), a promising source of biofuel, is induced upon nitrogen starvation (-N), but the proteins and genes involved in this process are poorly known. We performed isobaric tagging for relative and absolute quantification (iTRAQ)-based quantitative proteomics to identify Chlorella proteins with modulated expression under short-term -N. Out of 1736 soluble proteins and 2187 membrane-associated proteins identified, 288 and 56, respectively, were differentially expressed under -N. Gene expression analysis on select genes confirmed the same direction of mRNA modulation for most proteins. The MYB-related transcription factor ROC40 was the most induced protein, with a 9.6-fold increase upon -N. In a previously generated Chlamydomonas mutant, gravimetric measurements of crude total lipids revealed that roc40 was impaired in its ability to increase the accumulation of TAG upon -N, and this phenotype was complemented when wild-type Roc40 was expressed. Results from radiotracer experiments were consistent with the roc40 mutant being comparable to the wild type in recycling membrane lipids to TAG but being impaired in additional de novo synthesis of TAG during -N stress. In this study we provide evidence to support the hypothesis that transcription factor ROC40 has a role in -N-induced lipid accumulation, and uncover multiple previously unknown proteins modulated by short-term -N in green algae. PMID:26920093

  17. 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

  18. 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

    2016-01-01

    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

  19. 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.

  20. Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, Puerto Rico

    USGS Publications Warehouse

    Brown, Erik Thorson; Stallard, Robert F.; Larsen, Matthew C.; Raisbeck, Grant M.; Yiou, Francoise

    1995-01-01

    We present a simple method for estimation of long-term mean denudation rates using in situ-produced cosmogenic 10Be in fluvial sediments. Procedures are discussed to account for the effects of soil bioturbation, mass wasting and attenuation of cosmic rays by biomass and by local topography. Our analyses of 10Be in quartz from bedrock outcrops, soils, mass-wasting sites and riverine sediment from the Icacos River basin in the Luquillo Experimental Forest, Puerto Rico, are used to characterize denudation for major landform elements in that basin. The 10Be concentration of a discharge-weighted average of size classes of river sediment corresponds to a long-term average denudation of ≈ 43 m Ma −1, consistent with mass balance results. 

  1. 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

  2. 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. PMID:20118306

  3. Experimental evidence for state-dependent nest weight in the blue tit, Cyanistes caeruleus.

    PubMed

    Mainwaring, Mark C; Hartley, Ian R

    2009-05-01

    Parental investment in reproduction is generally limited by food availability, and so avian life-history research has traditionally focused on the brood rearing phase, when food requirements are greatest. Only relatively recently has the focus extended to the incubation phase, and even more recently to the nest-building phase, where observational and comparative evidence suggest that avian nest building is an energetically expensive and time-consuming activity. We aimed to experimentally test the limitations on this cost in a hole-breeding passerine, the blue tit (Cyanistes caeruleus), by providing supplementary food to experimental pairs during the nest-building period. In comparison with control females, that did not receive supplementary food, experimental females constructed heavier nests, with greater amounts of moss base but similar amounts of cup lining, despite there being no differences in the time taken to build the nest. This study provides empirical support for the hypothesis that avian nest building is a costly behaviour, limited by food availability. PMID:19429209

  4. Accumulate-Repeat-Accumulate-Accumulate Codes

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush; Dolinar, Samuel; Thorpe, Jeremy

    2007-01-01

    Accumulate-repeat-accumulate-accumulate (ARAA) codes have been proposed, inspired by the recently proposed accumulate-repeat-accumulate (ARA) codes. These are error-correcting codes suitable for use in a variety of wireless data-communication systems that include noisy channels. ARAA codes can be regarded as serial turbolike codes or as a subclass of low-density parity-check (LDPC) codes, and, like ARA codes they have projected graph or protograph representations; these characteristics make it possible to design high-speed iterative decoders that utilize belief-propagation algorithms. The objective in proposing ARAA codes as a subclass of ARA codes was to enhance the error-floor performance of ARA codes while maintaining simple encoding structures and low maximum variable node degree.

  5. Experimental evidence of dust-induced shaping of surface dissolved organic matter in the oligotrophic ocean

    NASA Astrophysics Data System (ADS)

    Pulido-Villena, Elvira; Djaoudi, Kahina; Barani, Aude; Charrière, Bruno; Delmont, Anne; Hélias-Nunige, Sandra; Marc, Tedetti; Wambeke France, Van

    2016-04-01

    Recent research has shown that dust deposition may impact the functioning of the microbial loop. On one hand, it enhances bacterial mineralization of dissolved organic matter (DOM), and so may limit the carbon export. On the other hand, the interaction between heterotrophic bacteria and DOM in the surface ocean can increase the residence time of DOM, promoting its export and sequestration in the deep ocean. The main goal of this study was to experimentally assess whether the bacterial response to dust deposition is prone to have an effect on the residence time of the DOM pool by modifying its bioavailability. The bacterial degradation of DOM was followed on dust-amended and control treatments during long-term incubations. Dissolved organic carbon concentration decreased by 9 μmol L-1 over the course of the experiment in both control and dust-enriched conditions, with no significant differences between treatments. However, significant differences in DOM optical properties appeared at the latest stage of the incubations suggesting an accumulation of DOM of high molecular weight in the dust-amended treatment. At the end of the incubations, the remaining water was filtered and re-used as a new culture medium for a bacterial natural assemblage. Bacterial abundance and production was lower in the treatment previously submitted to dust enrichment, suggesting a decrease in DOM lability after a dust deposition event. These preliminary results point to a new link between dust and ocean carbon cycle through the modification of the residence time of the DOM pool.

  6. Experimental evidence of large changes in terrestrial chlorine cycling following altered tree species composition.

    PubMed

    Montelius, Malin; Thiry, Yves; Marang, Laura; Ranger, Jacques; Cornelis, Jean-Thomas; Svensson, Teresia; Bastviken, David

    2015-04-21

    Organochlorine molecules (Clorg) are surprisingly abundant in soils and frequently exceed chloride (Cl(-)) levels. Despite the widespread abundance of Clorg and the common ability of microorganisms to produce Clorg, we lack fundamental knowledge about how overall chlorine cycling is regulated in forested ecosystems. Here we present data from a long-term reforestation experiment where native forest was cleared and replaced with five different tree species. Our results show that the abundance and residence times of Cl(-) and Clorg after 30 years were highly dependent on which tree species were planted on the nearby plots. Average Cl(-) and Clorg content in soil humus were higher, at experimental plots with coniferous trees than in those with deciduous trees. Plots with Norway spruce had the highest net accumulation of Cl(-) and Clorg over the experiment period, and showed a 10 and 4 times higher Cl(-) and Clorg storage (kg ha(-1)) in the biomass, respectively, and 7 and 9 times higher storage of Cl(-) and Clorg in the soil humus layer, compared to plots with oak. The results can explain why local soil chlorine levels are frequently independent of atmospheric deposition, and provide opportunities for improved modeling of chlorine distribution and cycling in terrestrial ecosystems. PMID:25811074

  7. Complex proteinopathy with accumulations of prion protein, hyperphosphorylated tau, α-synuclein and ubiquitin in experimental bovine spongiform encephalopathy of monkeys

    PubMed Central

    Cervenak, Juraj; Bu, Ming; Miller, Lindsay; Asher, David M.

    2014-01-01

    Proteins aggregate in several slowly progressive neurodegenerative diseases called ‘proteinopathies’. Studies with cell cultures and transgenic mice overexpressing mutated proteins suggested that aggregates of one protein induced misfolding and aggregation of other proteins as well – a possible common mechanism for some neurodegenerative diseases. However, most proteinopathies are ‘sporadic’, without gene mutation or overexpression. Thus, proteinopathies in WT animals genetically close to humans might be informative. Squirrel monkeys infected with the classical bovine spongiform encephalopathy agent developed an encephalopathy resembling variant Creutzfeldt–Jakob disease with accumulations not only of abnormal prion protein (PrPTSE), but also three other proteins: hyperphosphorylated tau (p-tau), α-synuclein and ubiquitin; β-amyloid protein (Aβ) did not accumulate. Severity of brain lesions correlated with spongiform degeneration. No amyloid was detected. These results suggested that PrPTSE enhanced formation of p-tau and aggregation of α-synuclein and ubiquitin, but not Aβ, providing a new experimental model for neurodegenerative diseases associated with complex proteinopathies. PMID:24769839

  8. Experimental evaluation of decrease in the activities of polyphosphate/glycogen-accumulating organisms due to cell death and activity decay in activated sludge.

    PubMed

    Hao, Xiaodi; Wang, Qilin; Cao, Yali; van Loosdrecht, Mark C M

    2010-06-15

    Decrease in bacterial activity (biomass decay) in activated sludge can result from cell death (reduction in the amount of active bacteria) and activity decay (reduction in the specific activity of active bacteria). The goal of this study was to experimentally differentiate between cell death and activity decay as the cause of decrease in bacterial activity. By means of measuring maximal anaerobic phosphate release rates, verifying membrane integrity by live/dead staining and verifying presence of 16S rRNA with fluorescence in situ hybridization (FISH), the decay rates and death rates of polyphosphate-accumulating organisms (PAOs) in a biological nutrient removal (BNR) system and a laboratory phosphate removing sequencing batch reactor (SBR) system were determined, respectively, under famine conditions. In addition, the decay rate and death rate of glycogen-accumulating organisms (GAOs) in a SBR system with an enrichment culture of GAOs were also measured under famine conditions. Hereto the maximal anaerobic volatile fatty acid uptake rates, live/dead staining, and FISH were used. The experiments revealed that in the BNR and enriched PAO-SBR systems, activity decay contributed 58% and 80% to the decreased activities of PAOs, and that cell death was responsible for 42% and 20% of decreases in their respective activities. In the enriched GAOs system, activity decay constituted a proportion of 74% of the decreased activity of GAOs, and cell death only accounted for 26% of the decrease of their activity. PMID:20178124

  9. 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.

  10. 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

    2014-09-01

    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.

  11. Enjoyment: A Conceptual Exploration and Overview of Experimental Evidence in the Context of Games for Health.

    PubMed

    Crutzen, Rik; van 't Riet, Jonathan; Short, Camille E

    2016-02-01

    Enjoyment is consistently noted as important for engaging audiences in games for health. However, as a term, enjoyment is often used interchangeably with a host of other terms, some of which overlap conceptually. This obscures what does and what does not constitute enjoyment, and in turn slows scientific progress by making the study of enjoyment and the synthesis of enjoyment-related research difficult. This article is aimed at improving our understanding of enjoyment by distinguishing enjoyment from other important constructs, such as fun and engagement, and by providing an overview of the experimental evidence on the determinants of enjoyment in videogames. Competence, narrative transportation, and relevance are identified as key factors related to enjoyment, and future studies examining these factors using games for health are recommended. PMID:26699455

  12. First experimental evidence of the feasibility of multi-color magnetic particle imaging

    NASA Astrophysics Data System (ADS)

    Rahmer, J.; Halkola, A.; Gleich, B.; Schmale, I.; Borgert, J.

    2015-03-01

    Magnetic particle imaging is a new approach to visualizing magnetic nanoparticles. It is capable of 3D real-time in vivo imaging of particles injected into the blood stream and is a candidate for medical imaging applications. To date, only one particle type has been imaged at a time, however, the ability to separate signals acquired simultaneously from different particle types or from particles in different environments would substantially increase the scope of the method. Different colors could be assigned to different signal sources to allow for visualization in a single image. Successful signal separation has been reported in spectroscopic experiments, but it was unclear how well separation would work in conjunction with spatial encoding in an imaging experiment. This work presents experimental evidence of the separability of signals from different particle types and aggregation states (fluid versus powder) using a ‘multi-color’ reconstruction approach. Several mechanisms are discussed that may form the basis for successful signal separation.

  13. 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. PMID:24428753

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

    PubMed

    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

  15. 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

  16. Experimental evidence for alleviating nociceptive hypersensitivity by single application of capsaicin.

    PubMed

    Ma, Xiao-Li; Zhang, Fang-Xiong; Dong, Fei; Bao, Lan; Zhang, Xu

    2015-01-01

    The single application of high-concentration of capsaicin has been used as an analgesic therapy of persistent pain. However, its effectiveness and underlying mechanisms remain to be further evaluated with experimental approaches. The present study provided evidence showing that the single application of capsaicin dose-dependently alleviated nociceptive hypersensitivity, and reduced the action potential firing in small-diameter neurons of the dorsal root ganglia (DRG) in rats and mice. Pre-treatment with capsaicin reduced formalin-induced acute nocifensive behavior after a brief hyperalgesia in rats and mice. The inhibitory effects of capsaicin were calcium-dependent, and mediated by the capsaicin receptor (transient receptor potential vanilloid type-1). We further found that capsaicin exerted inhibitory effects on the persistent nociceptive hypersensitivity induced by peripheral inflammation and nerve injury. Thus, these results support the long-lasting and inhibitory effects of topical capsaicin on persistent pain, and the clinic use of capsaicin as a pain therapy. PMID:25896608

  17. 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. PMID:25267469

  18. 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

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

    PubMed

    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

  20. 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.

  1. 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

  2. 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. PMID:21561964

  3. Developmental neurotoxicity of ortho-phthalate diesters: review of human and experimental evidence.

    PubMed

    Miodovnik, Amir; Edwards, Andrea; Bellinger, David C; Hauser, Russ

    2014-03-01

    Ortho-phthalate diesters, or phthalates, are widely used synthetic chemicals found primarily in consumer products and polyvinyl chloride plastics. Experimental evidence suggests that several phthalates possess antiandrogenic properties and may disrupt endocrine pathways resulting in abnormal reproductive outcomes. Low-level exposure to phthalates has been well documented in humans, with higher levels found in children and women of childbearing age. Recent epidemiologic studies postulate that prenatal exposure to measurable urine phthalate concentrations may be associated with altered genital and pubertal development in infants and children. This review addresses the emerging evidence that some phthalates may have an adverse impact on the developing brain. The supporting animal studies and proposed mechanisms underlying the deleterious properties of phthalates in relation to neurodevelopmental outcomes are also discussed. While the observed associations are based on limited studies with a broad range of endpoints, the implications of such outcomes are of concern from a public health standpoint and merit further investigation given the widespread nature of the exposure. PMID:24486776

  4. 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. PMID:27470424

  5. 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. PMID:11806503

  6. Genetic and experimental evidence for cross-species infection by swine hepatitis E virus.

    PubMed

    Meng, X J; Halbur, P G; Shapiro, M S; Govindarajan, S; Bruna, J D; Mushahwar, I K; Purcell, R H; Emerson, S U

    1998-12-01

    Prior to the recent discovery of the swine hepatitis E virus (swine HEV) in pigs from the midwestern United States, HEV was not considered endemic to this country. Since swine HEV is antigenically and genetically related to human strains of HEV, it was important to characterize this new virus further. The infectivity titer of a pool of swine HEV in pigs was determined in order to prepare a standardized reagent and to evaluate the dose response in pigs. Although the sequence of swine HEV varied extensively from those of most human strains of HEV, it was very closely related to the two strains of human HEV (US-1 and US-2) isolated in the United States. The U.S. strains which were recently recovered from two patients with clinical hepatitis E in the United States shared >/=97% amino acid identity with swine HEV in open reading frames 1 and 2. Phylogenetic analyses of different regions of the genome revealed that swine HEV and the U.S. strains grouped together and formed a distinct branch. These results suggested that swine HEV may infect humans. When we inoculated rhesus monkeys and a chimpanzee, experimental surrogates of humans, with swine HEV, the primates became infected. Furthermore, in a reciprocal experiment, specific-pathogen-free pigs were experimentally infected with the US-2 strain of human HEV that is genetically similar to swine HEV. These results provided experimental evidence for cross-species infection by the swine virus. Thus, humans appear to be at risk of infection with swine HEV or closely related viruses. PMID:9811705

  7. Experimental Evidence for Polybaric Intracrustal Differentiation of Primitive Arc Basalt beneath St. Vincent, Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Blundy, Jon; Melekhova, Lena; Robertson, Richard

    2014-05-01

    country rocks composed of ancestral, solidified basalt. Isotopic data for St. Vincent (Heath et al, J Petrol, 1998) rule out any involvement of much older sialic crust. Although our experimental glasses provide a very good match to erupted lavas, the compositions of residual minerals do not match those of cumulate xenoliths (Tollan et al, CMP, 2012), which are abundant on St. Vincent. Therefore cumulates are not entrained fragments of the source region, but shallow accumulations of crystals generated by cooling of magmas on their journey through the crust. Thus melt compositions are a consequence of high pressure, H2O-understaurated phase relations, whereas cumulates are a consequence of low pressure, typically H2O-saturated, phase relations. We integrate these findings into a simple polybaric model of magma differentiation on St. Vincent involving a single, high-Mg, mantle-derived parental basalt.

  8. Experimental and model-based evaluation of the role of denitrifying polyphosphate accumulating organisms at two large scale WWTPs in northern Poland.

    PubMed

    Makinia, J; Rosenwinkel, K H; Swinarski, M; Dobiegala, E

    2006-01-01

    The capabilities of denitrifying Polyphosphate Accumulating Organisms (DPAOs) in two large-scale plants in northern Poland performing enhanced biological phosphorus removal (EBPR) were evaluated in this study. A series of batch tests with the process biomass aimed at the measurements of phosphate release (with artificial substrate and real wastewater) and subsequent phosphate uptake under anoxic/aerobic conditions. The process kinetics were predicted using ASM2d implemented in the GPS-X ver. 4.0.2 simulation package. The results from one experimental series (summer) were used for the model calibration, whereas the results from another series (spring) were used for the model validation. The model parameters were also accurately confirmed by predictions of the accompanying field measurements in the full-scale bioreactors. The experimental and simulation results revealed that a relatively small fraction of PAO could denitrify (eta(NO3,PAO) = 0.32). The denitrification rates associated with the anoxic storage of PP and the anoxic growth of PAO only constituted 16.0-21.0% of the denitrification rates associated with the anoxic activity of "ordinary" heterotrophs. PMID:17163015

  9. The benefits of synchronous collaborative information visualization: evidence from an experimental evaluation.

    PubMed

    Bresciani, Sabrina; Eppler, Martin J

    2009-01-01

    A great corpus of studies reports empirical evidence of how information visualization supports comprehension and analysis of data. The benefits of visualization for synchronous group knowledge work, however, have not been addressed extensively. Anecdotal evidence and use cases illustrate the benefits of synchronous collaborative information visualization, but very few empirical studies have rigorously examined the impact of visualization on group knowledge work. We have consequently designed and conducted an experiment in which we have analyzed the impact of visualization on knowledge sharing in situated work groups. Our experimental study consists of evaluating the performance of 131 subjects (all experienced managers) in groups of 5 (for a total of 26 groups), working together on a real-life knowledge sharing task. We compare (1) the control condition (no visualization provided), with two visualization supports: (2) optimal and (3) suboptimal visualization (based on a previous survey). The facilitator of each group was asked to populate the provided interactive visual template with insights from the group, and to organize the contributions according to the group consensus. We have evaluated the results through both objective and subjective measures. Our statistical analysis clearly shows that interactive visualization has a statistically significant, objective and positive impact on the outcomes of knowledge sharing, but that the subjects seem not to be aware of this. In particular, groups supported by visualization achieved higher productivity, higher quality of outcome and greater knowledge gains. No statistically significant results could be found between an optimal and a suboptimal visualization though (as classified by the pre-experiment survey). Subjects also did not seem to be aware of the benefits that the visualizations provided as no difference between the visualization and the control conditions was found for the self-reported measures of satisfaction

  10. 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.

  11. Genetic evidence for a role of BiP/Kar2 that regulates Ire1 in response to accumulation of unfolded proteins.

    PubMed

    Kimata, Yukio; Kimata, Yuki I; Shimizu, Yusuke; Abe, Hiroshi; Farcasanu, Ileana C; Takeuchi, Masato; Rose, Mark D; Kohno, Kenji

    2003-06-01

    In the unfolded protein response (UPR) signaling pathway, accumulation of unfolded proteins in the endoplasmic reticulum (ER) activates a transmembrane kinase/ribonuclease Ire1, which causes the transcriptional induction of ER-resident chaperones, including BiP/Kar2. It was previously hypothesized that BiP/Kar2 plays a direct role in the signaling mechanism. In this model, association of BiP/Kar2 with Ire1 represses the UPR pathway while under conditions of ER stress, BiP/Kar2 dissociation leads to activation. To test this model, we analyzed five temperature-sensitive alleles of the yeast KAR2 gene. When cells carrying a mutation in the Kar2 substrate-binding domain were incubated at the restrictive temperature, association of Kar2 to Ire1 was disrupted, and the UPR pathway was activated even in the absence of extrinsic ER stress. Conversely, cells carrying a mutation in the Kar2 ATPase domain, in which Kar2 poorly dissociated from Ire1 even in the presence of tunicamycin, a potent inducer of ER stress, were unable to activate the pathway. Our findings provide strong evidence in support of BiP/Kar2-dependent Ire1 regulation model and suggest that Ire1 associates with Kar2 as a chaperone substrate. We speculate that recognition of unfolded proteins is based on their competition with Ire1 for binding with BiP/Kar2. PMID:12808051

  12. Genetic Evidence for a Role of BiP/Kar2 That Regulates Ire1 in Response to Accumulation of Unfolded Proteins

    PubMed Central

    Kimata, Yukio; Kimata, Yuki I.; Shimizu, Yusuke; Abe, Hiroshi; Farcasanu, Ileana C.; Takeuchi, Masato; Rose, Mark D.; Kohno, Kenji

    2003-01-01

    In the unfolded protein response (UPR) signaling pathway, accumulation of unfolded proteins in the endoplasmic reticulum (ER) activates a transmembrane kinase/ribonuclease Ire1, which causes the transcriptional induction of ER-resident chaperones, including BiP/Kar2. It was previously hypothesized that BiP/Kar2 plays a direct role in the signaling mechanism. In this model, association of BiP/Kar2 with Ire1 represses the UPR pathway while under conditions of ER stress, BiP/Kar2 dissociation leads to activation. To test this model, we analyzed five temperature-sensitive alleles of the yeast KAR2 gene. When cells carrying a mutation in the Kar2 substrate-binding domain were incubated at the restrictive temperature, association of Kar2 to Ire1 was disrupted, and the UPR pathway was activated even in the absence of extrinsic ER stress. Conversely, cells carrying a mutation in the Kar2 ATPase domain, in which Kar2 poorly dissociated from Ire1 even in the presence of tunicamycin, a potent inducer of ER stress, were unable to activate the pathway. Our findings provide strong evidence in support of BiP/Kar2-dependent Ire1 regulation model and suggest that Ire1 associates with Kar2 as a chaperone substrate. We speculate that recognition of unfolded proteins is based on their competition with Ire1 for binding with BiP/Kar2. PMID:12808051

  13. 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

  14. 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

  15. Lanthanide humic substances complexation. I. Experimental evidence for a lanthanide contraction effect

    NASA Astrophysics Data System (ADS)

    Sonke, Jeroen E.; Salters, Vincent J. M.

    2006-03-01

    The interaction of the lanthanides (Ln) with humic substances (HS) was investigated with a novel chemical speciation tool, Capillary Electrophoresis-Inductively Coupled Plasma Mass Spectrometry (CE-ICP-MS). By using an EDTA-ligand competition method, a bi-modal species distribution of LnEDTA and LnHS is attained, separated by CE, and detected online by sector field ICP-MS. We quantified the binding of all 14 rare earth elements (REEs), Sc and Y with Suwannee river fulvic acid, Leonardite coal humic acid, and Elliot soil humic acid under environmental conditions (pH 6-9, 0.001-0.1 mol L -1 NaNO 3, 1-1000 nmol L -1 Ln, 10-20 mg L -1 HS). Conditional binding constants for REE-HS interaction ( Kc) ranged from 8.9 < log Kc < 16.5 under all experimental conditions, and display a lanthanide contraction effect, ΔLKc: a gradual increase in Kc from La to Lu by 2-3 orders of magnitude as a function of decreasing ionic radius. HS polyelectrolyte effects cause Kc to increase with increasing pH and decreasing ionic strength. ΔLKc increases significantly with increasing pH, and likely with decreasing ionic strength. Based on a strong correlation between ΔLKc values and denticity for organic acids, we suggest that HS form a range of tri- to tetra-dentate complexes under environmental conditions. These results confirm HS to be a strong complexing agent for Ln, and show rigorous experimental evidence for potential REE fractionation by HS complexation.

  16. Transanal total mesorectal excision: a systematic review of the experimental and clinical evidence.

    PubMed

    Araujo, S E; Crawshaw, B; Mendes, C R; Delaney, C P

    2015-02-01

    Achieving a clear distal or circumferential resection margins with laparoscopic total mesorectal excision (TME) may be laborious, especially in obese males and when operating on advanced distal rectal tumors with a poor response to neoadjuvant treatment. Transanal (TaTME) is a new natural orifice translumenal endoscopic surgery modality in which the rectum is mobilized transanally using endoscopic techniques with or without laparoscopic assistance. We conducted a comprehensive systematic review of publications on this new technique in PubMed and Embase databases from January, 2008, to July, 2014. Experimental and clinical studies written in English were included. Experimental research with TaTME was done on pigs with and without survival models and on human cadavers. In these studies, laparoscopic or transgastric assistance was frequently used resulting in an easier upper rectal dissection and in a longer rectal specimen. To date, 150 patients in 16 clinical studies have undergone TaTME. In all but 15 cases, transabdominal assistance was used. A rigid transanal endoscopic operations/transanal endoscopic microsurgery (TEO/TEM) platform was used in 37 patients. Rectal adenocarcinoma was the indication in all except for nine cases of benign diseases. Operative times ranged from 90 to 460 min. TME quality was deemed intact, satisfactory, or complete. Involvement in circumferential resection margins was detected in 16 (11.8 %) patients. The mean lymph node harvest was equal or greater than 12 in all studies. Regarding morbidity, pneumoretroperitoneum, damage to the urethra, and air embolism were reported intraoperatively. Mean hospital stay varied from 4 to 14 days. Postoperative complications occurred in 34 (22.7 %) patients. TaTME with TEM is feasible in selected cases. Oncologic safety parameters seem to be adequate although the evidence relies on small retrospective series conducted by highly trained surgeons. Further studies are expected. PMID:25380741

  17. 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

  18. REDUCTIVE BIOTRANSFORMATION OF TETRACHLOROETHENE TO ETHENE DURING ANAEROBIC DEGRADATION OF TOLUENE: EXPERIMENTAL EVIDENCE AND KINETICS

    EPA Science Inventory

    Reductive biotransformation of tetrachloroethene (PCE) to ethene occurred during anaerobic degradation of toluene in an enrichment culture. Ethene was detected as a dominant daughter product of PCE dechlorination with negligible accumulation of other partially chlorinated ethenes...

  19. 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. PMID:24889601

  20. 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. PMID:27028073

  1. 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.

  2. 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

  3. Experimental evidence of lateral flow in unsaturated homogeneous isotropic sloping soil due to rainfall

    NASA Astrophysics Data System (ADS)

    Sinai, G.; Dirksen, C.

    2006-12-01

    This paper describes laboratory experimental evidence for lateral flow in the top layer of unsaturated sloping soil due to rainfall. Water was applied uniformly on horizontal and V-shaped surfaces of fine sand, at rates about 100 times smaller than the saturated hydraulic conductivity. Flow regimes near the surface and in the soil bulk were studied by using dyes. Streamlines and streak lines and wetting fronts were visually studied and photographed through a vertical glass wall. Near wetting fronts the flow direction was always perpendicular to the fronts owing to dominant matrix potential gradients. Thus, during early wetting of dry sloping sand, the flow direction is directed upslope. Far above a wetting front the flow was vertical due to the dominance of gravity. Downslope flow was observed during decreasing rainfall and dry periods. The lateral movement was largest near the soil surface and decayed with soil depth. Unstable downslope lateral flow close to the soil surface was attributed to non-Darcian flow due to variable temporal and spatial raindrop distributions. The experiments verify the theory that predicts unsaturated downslope lateral flow in sloping soil due to rainfall dynamics only, without apparent soil texture difference or anisotropy. This phenomenon could have significant implications for hillside hydrology, desert agriculture, irrigation management, etc., as well as for the basic mechanisms of surface runoff and erosion.

  4. Experimental evidence for non-Abelian gauge potentials in twisted graphene bilayers

    NASA Astrophysics Data System (ADS)

    Yin, Long-Jing; Qiao, Jia-Bin; Zuo, Wei-Jie; Li, Wen-Tian; He, Lin

    2015-08-01

    Non-Abelian gauge potentials are quite relevant in subatomic physics, but they are relatively rare in a condensed matter context. Here we report the experimental evidence for non-Abelian gauge potentials in twisted graphene bilayers by scanning tunneling microscopy and spectroscopy. At a magic twisted angle, θ ≈(1.11±0.05 ) ∘ , a pronounced sharp peak, which arises from the nondispersive flat bands at the charge neutrality point, is observed in the tunneling density of states due to the action of the non-Abelian gauge fields. Moreover, we observe confined electronic states in the twisted bilayer, as manifested by regularly spaced tunneling peaks with energy spacing δ E ≈vF/D ≈70 meV (here vF is the Fermi velocity of graphene and D is the period of the moiré patterns). This indicates that the non-Abelian gauge potentials in twisted graphene bilayers confine low-energy electrons into a triangular array of quantum dots following the modulation of the moiré patterns. Our results also directly demonstrate that the Fermi velocity in twisted bilayers can be tuned from about 106m /s to zero by simply reducing the twisted angle of about 2∘.

  5. 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.

  6. 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.

  7. Evidence for effects of chronic lead exposure on blood pressure in experimental animals: an overview

    SciTech Connect

    Victery, W.

    1988-06-01

    Information obtained in a number of experimental studies conducted over the last 40 years on the effects of lead on blood pressure is reviewed. Differences in animal species, age at beginning of exposure, level of lead exposure, indices of lead burden, and blood pressure effects on each study are reported. In several of the high-dose experiments, hypertension was observed, but nephrotoxicity of lead may have contributed to its development. Moreover, in other high-dose experiments, no hypertension was observed, and in at least one experiment, the evidence suggested that lead could reduce an elevated blood pressure. In contrast, the lower dose experiments consistently demonstrated a hypertensive effect. Overall, the data suggest a biphasic dose response. Establishment of an appropriate animal model to study blood pressure effects of lead will require careful assessment of dietary interactions with lead, unstressed blood pressure monitoring with standardized techniques, and documentation of biologically effective lead burden. Future research should examine lead exposure at more environmentally appropriate levels in order to determine the validity of associating this pollutant with blood pressure effects in human population.

  8. 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. PMID:23646942

  9. Experimental evidence of O-H—S hydrogen bonding in supersonic jet

    NASA Astrophysics Data System (ADS)

    Biswal, Himansu S.; Chakraborty, Shamik; Wategaonkar, Sanjay

    2008-11-01

    Experimental evidence is presented for the O-H—S hydrogen bonding in the complexes of simple model compounds of methionine (dimethyl sulphide) and tyrosine (phenol, p-cresol, and 2-naphthol). The complexes were formed in the supersonic jet and were detected using resonantly enhanced multiphoton ionization spectroscopy. In all the complexes, the band origins for the S1-S0 electronic transition were redshifted relative to that of their respective monomers. The resonant ion depletion IR spectra of all the complexes show redshifts of 123-140 cm-1 in the O-H stretching frequency, indicating that the OH group acts as the hydrogen bond donor and sulfur as an acceptor. The density functional theory calculations also predict the stable structures in support of this and predict the redshifted O-H stretching frequency in the complex. The atoms-in-molecules and natural bond orbital calculations confirm the O-H—S hydrogen bonding interaction. The significant finding of this study is that the magnitudes of redshifts in the O-H stretch in the O-H—S hydrogen bonded complexes reported here are comparable to those reported for the O-H—O hydrogen bonded complexes where H2O acts as the H-bond acceptor, which suggests that the OH-S interaction is perhaps as strong as the OH-O interaction. To the best of our knowledge, this is the first such report on the O-H—S hydrogen bonded complexes.

  10. Proprioceptive Dysfunction in Focal Dystonia: From Experimental Evidence to Rehabilitation Strategies

    PubMed Central

    Avanzino, Laura; Fiorio, Mirta

    2014-01-01

    Dystonia has historically been considered a disorder of the basal ganglia, mainly affecting planning and execution of voluntary movements. This notion comes from the observation that most lesions responsible for secondary dystonia involve the basal ganglia. However, what emerges from recent research is that dystonia is linked to the dysfunction of a complex neural network that comprises basal ganglia–thalamic–frontal cortex, but also the inferior parietal cortex and the cerebellum. While dystonia is clearly a motor problem, it turned out that sensory aspects are also fundamental, especially those related to proprioception. We outline experimental evidence for proprioceptive dysfunction in focal dystonia from intrinsic sensory abnormalities to impaired sensorimotor integration, which is the process by which sensory information is used to plan and execute volitional movements. Particularly, we will focus on proprioceptive aspects of dystonia, including: (i) processing of vibratory input, (ii) temporal discrimination of two passive movements, (iii) multimodal integration of visual-tactile and proprioceptive inputs, and (iv) motor control in the absence of visual feedback. We suggest that these investigations contribute not only to a better understanding of dystonia pathophysiology, but also to develop rehabilitation strategies aimed at facilitating the processing of proprioceptive input. PMID:25538612

  11. Experimental evidence of dual emission in a negatively solvatochromic push-pull pyridinium derivative.

    PubMed

    Carlotti, B; Cesaretti, A; Fortuna, C G; Spalletti, A; Elisei, F

    2015-01-21

    We report here experimental evidence of dual emission in a cationic push-pull system (bearing a methyl pyridinium group as an electron acceptor and a diphenylamino group as an electron donor), which shows negative solvatochromism. An intriguing blue shift and enlargement of the fluorescence band upon increasing the solvent polarity have suggested a possible contribution of an upper excited state to the stationary emission. Ultrafast transient absorption has indeed revealed the presence of an intermediate transient species in some solvents. The investigation of the fluorescence properties at low temperatures and in the rigid matrix has given a clear indication of this additional emission at shorter wavelengths. Femtosecond up-conversion measurements have shown interesting rise-decay dynamics in the kinetics and two well distinguished emission bands characterized by different deactivations. A single isoemissive point in the time-resolved area-normalized spectra has unambiguously pointed out the presence of two consecutive emissive species: the locally excited and the intramolecular charge transfer excited states. PMID:25474173

  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. First experimental evidence of the feasibility of multi-color magnetic particle imaging.

    PubMed

    Rahmer, J; Halkola, A; Gleich, B; Schmale, I; Borgert, J

    2015-03-01

    Magnetic particle imaging is a new approach to visualizing magnetic nanoparticles. It is capable of 3D real-time in vivo imaging of particles injected into the blood stream and is a candidate for medical imaging applications. To date, only one particle type has been imaged at a time, however, the ability to separate signals acquired simultaneously from different particle types or from particles in different environments would substantially increase the scope of the method. Different colors could be assigned to different signal sources to allow for visualization in a single image. Successful signal separation has been reported in spectroscopic experiments, but it was unclear how well separation would work in conjunction with spatial encoding in an imaging experiment. This work presents experimental evidence of the separability of signals from different particle types and aggregation states (fluid versus powder) using a 'multi-color' reconstruction approach. Several mechanisms are discussed that may form the basis for successful signal separation. PMID:25658130

  14. 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

  15. 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. PMID:25419704

  16. Field experimental evidence that stochastic processes predominate in the initial assembly of bacterial communities.

    PubMed

    Hao, Yi-Qi; Zhao, Xin-Feng; Zhang, Da-Yong

    2016-06-01

    To assess the relative importance of environmental selection, dispersal and stochastic processes in structuring ecological communities, we conducted a bacterial community assembly experiment using microcosms filled with sterile liquid medium under field conditions in the Inner Mongolian grasslands. Multiple replicate microcosms containing different carbon substrates were placed at nine locations across three spatial scales (10, 300 and 10 000 m distance between locations) in such a way that the environment of microcosms varies independently of the geographical distance. The operational taxonomic units within the experimental communities were assessed via the terminal restriction fragment length polymorphism techniques on the 10th and 17th days after the onset of the experiment. We found no evidence of distance decay in community similarity, and communities within a given location were more similar to each other regardless of environment than communities at other locations within the same spatial scale. Variance partitioning indicated that location explained more compositional variation in microbial communities than environment, particularly on the 17th day, despite that environment and location in combination could only explain less than half of the total variation. These results suggest that bacterial dispersal is not limited by distance in this experiment, and community assembly in microcosms is not environmentally determined but governed by stochastic processes. PMID:25809418

  17. 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.

  18. Analysis of Sensitive CO2 Pathways and Genes Related to Carbon Uptake and Accumulation in Chlamydomonas reinhardtii through Genomic Scale Modeling and Experimental Validation

    PubMed Central

    Winck, Flavia V.; Melo, David O. Páez; Riaño-Pachón, Diego M.; Martins, Marina C. M.; Caldana, Camila; Barrios, Andrés F. González

    2016-01-01

    The development of microalgae sustainable applications needs better understanding of microalgae biology. Moreover, how cells coordinate their metabolism toward biomass accumulation is not fully understood. In this present study, flux balance analysis (FBA) was performed to identify sensitive metabolic pathways of Chlamydomonas reinhardtii under varied CO2 inputs. The metabolic network model of Chlamydomonas was updated based on the genome annotation data and sensitivity analysis revealed CO2 sensitive reactions. Biological experiments were performed with cells cultivated at 0.04% (air), 2.5, 5, 8, and 10% CO2 concentration under controlled conditions and cell growth profiles and biomass content were measured. Pigments, lipids, proteins, and starch were further quantified for the reference low (0.04%) and high (10%) CO2 conditions. The expression level of candidate genes of sensitive reactions was measured and validated by quantitative real time PCR. The sensitive analysis revealed mitochondrial compartment as the major affected by changes on the CO2 concentrations and glycolysis/gluconeogenesis, glyoxylate, and dicarboxylate metabolism among the affected metabolic pathways. Genes coding for glycerate kinase (GLYK), glycine cleavage system, H-protein (GCSH), NAD-dependent malate dehydrogenase (MDH3), low-CO2 inducible protein A (LCIA), carbonic anhydrase 5 (CAH5), E1 component, alpha subunit (PDC3), dual function alcohol dehydrogenase/acetaldehyde dehydrogenase (ADH1), and phosphoglucomutase (GPM2), were defined, among other genes, as sensitive nodes in the metabolic network simulations. These genes were experimentally responsive to the changes in the carbon fluxes in the system. We performed metabolomics analysis using mass spectrometry validating the modulation of carbon dioxide responsive pathways and metabolites. The changes on CO2 levels mostly affected the metabolism of amino acids found in the photorespiration pathway. Our updated metabolic network was

  19. Analysis of Sensitive CO2 Pathways and Genes Related to Carbon Uptake and Accumulation in Chlamydomonas reinhardtii through Genomic Scale Modeling and Experimental Validation.

    PubMed

    Winck, Flavia V; Melo, David O Páez; Riaño-Pachón, Diego M; Martins, Marina C M; Caldana, Camila; Barrios, Andrés F González

    2016-01-01

    The development of microalgae sustainable applications needs better understanding of microalgae biology. Moreover, how cells coordinate their metabolism toward biomass accumulation is not fully understood. In this present study, flux balance analysis (FBA) was performed to identify sensitive metabolic pathways of Chlamydomonas reinhardtii under varied CO2 inputs. The metabolic network model of Chlamydomonas was updated based on the genome annotation data and sensitivity analysis revealed CO2 sensitive reactions. Biological experiments were performed with cells cultivated at 0.04% (air), 2.5, 5, 8, and 10% CO2 concentration under controlled conditions and cell growth profiles and biomass content were measured. Pigments, lipids, proteins, and starch were further quantified for the reference low (0.04%) and high (10%) CO2 conditions. The expression level of candidate genes of sensitive reactions was measured and validated by quantitative real time PCR. The sensitive analysis revealed mitochondrial compartment as the major affected by changes on the CO2 concentrations and glycolysis/gluconeogenesis, glyoxylate, and dicarboxylate metabolism among the affected metabolic pathways. Genes coding for glycerate kinase (GLYK), glycine cleavage system, H-protein (GCSH), NAD-dependent malate dehydrogenase (MDH3), low-CO2 inducible protein A (LCIA), carbonic anhydrase 5 (CAH5), E1 component, alpha subunit (PDC3), dual function alcohol dehydrogenase/acetaldehyde dehydrogenase (ADH1), and phosphoglucomutase (GPM2), were defined, among other genes, as sensitive nodes in the metabolic network simulations. These genes were experimentally responsive to the changes in the carbon fluxes in the system. We performed metabolomics analysis using mass spectrometry validating the modulation of carbon dioxide responsive pathways and metabolites. The changes on CO2 levels mostly affected the metabolism of amino acids found in the photorespiration pathway. Our updated metabolic network was

  20. 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…

  1. Evidence of Experimental Vertical Transmission of Emerging Novel ECSA Genotype of Chikungunya Virus in Aedes aegypti

    PubMed Central

    Agarwal, Ankita; Dash, Paban Kumar; Singh, Anil Kumar; Sharma, Shashi; Gopalan, Natarajan; Rao, Putcha Venkata Lakshmana; Parida, Man Mohan; Reiter, Paul

    2014-01-01

    Background Chikungunya virus (CHIKV) has emerged as one of the most important arboviruses of public health significance in the past decade. The virus is mainly maintained through human-mosquito-human cycle. Other routes of transmission and the mechanism of maintenance of the virus in nature are not clearly known. Vertical transmission may be a mechanism of sustaining the virus during inter-epidemic periods. Laboratory experiments were conducted to determine whether Aedes aegypti, a principal vector, is capable of vertically transmitting CHIKV or not. Methodology/Principal Findings Female Ae. aegypti were orally infected with a novel ECSA genotype of CHIKV in the 2nd gonotrophic cycle. On day 10 post infection, a non-infectious blood meal was provided to obtain another cycle of eggs. Larvae and adults developed from the eggs obtained following both infectious and non-infectious blood meal were tested for the presence of CHIKV specific RNA through real time RT-PCR. The results revealed that the larvae and adults developed from eggs derived from the infectious blood meal (2nd gonotrophic cycle) were negative for CHIKV RNA. However, the larvae and adults developed after subsequent non-infectious blood meal (3rd gonotrophic cycle) were positive with minimum filial infection rates of 28.2 (1∶35.5) and 20.2 (1∶49.5) respectively. Conclusion/Significance This study is the first to confirm experimental vertical transmission of emerging novel ECSA genotype of CHIKV in Ae. aegypti from India, indicating the possibilities of occurrence of this phenomenon in nature. This evidence may have important consequence for survival of CHIKV during adverse climatic conditions and inter-epidemic periods. PMID:25080107

  2. Euphol prevents experimental autoimmune encephalomyelitis in mice: evidence for the underlying mechanisms.

    PubMed

    Dutra, Rafael Cypriano; de Souza, Paula Roberta de Cezaro; Bento, Allisson Freire; Marcon, Rodrigo; Bicca, Maíra Assunção; Pianowski, Luiz Francisco; Calixto, João B

    2012-02-15

    Multiple sclerosis (MS) is a severe chronic T cell-mediated autoimmune inflammatory disease of the central nervous system (CNS), the existing therapy of which is only partially effective and is associated with undesirable side effects. Euphol, an alcohol tetracyclic triterpene, has a wide range of pharmacological properties and is considered to have anti-inflammatory action. However there are no reports about the effects and mechanisms of euphol in experimental autoimmune encephalomyelitis (EAE), an established model of MS. Here we report the effects and the underlying mechanisms of action of euphol in EAE. Euphol (1-10mg/kg) was administered orally at different time-points of EAE. Immunological and inflammatory responses were evaluated by real-time PCR, Western blot and flow cytometry assays. We provide evidence that euphol significantly attenuates neurological signs of EAE. These beneficial effects of euphol seem to be associated with the down-regulation of mRNA and protein expression of some pro-inflammatory mediators such as TNF-α, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the CNS. Furthermore, in vitro, euphol consistently inhibited the T cell-mediated immune response including the production of T(H)1 and T(H)17 cytokines in spleen cells of untreated EAE animals. Likewise, oral euphol treatment inhibited the infiltration of T(H)17 myelin-specific cells into the CNS through the adhesion molecule, lymphocyte function-associated antigen 1 (LFA-1). Our findings reveal that oral administration of euphol consistently reduces and limits the severity and development of EAE. Therefore, euphol might represent a potential molecule of interest for the treatment of MS and other T(H)17 cell-mediated inflammatory diseases. PMID:22155310

  3. 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

  4. 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

  5. Experimental evidence for thermal generation of interstitials in a metallic crystal near the melting temperature.

    PubMed

    Safonova, E V; Mitrofanov, Yu P; Konchakov, R A; Yu Vinogradov, A; Kobelev, N P; Khonik, V A

    2016-06-01

    The only intrinsic point defects of simple crystalline metals known from solid state physics are vacancies and interstitials. It is widely believed that while vacancies play a major role in crystal properties and their concentration reaches relatively big values near the melting temperature T m, interstitials essentially do not occur in thermodynamic equilibrium and their influence on properties is minor. Here, taking aluminum single crystals as an example, we present compelling experimental evidence for rapid thermoactivated growth of interstitial concentration upon approaching T m. Using high precision measurements of the shear modulus we found a diaelastic effect of up to [Formula: see text] near T m. It is argued that this effect is mostly due to the generation of dumbbell (split) interstitials. The interstitial concentration c i rapidly increases upon approaching T m and becomes only 2-3 times smaller than that of vacancies just below T m. The reason for this c i -increase is conditioned by a decrease of the Gibbs free energy with temperature, which in turn originates from the high formation entropy of dumbbell interstitials and a decrease of their formation enthalpy at high c i . Special molecular dynamic simulation confirmed all basic aspects of the proposed interpretation. The results obtained (i) demonstrate the significance of interstitial concentration near T m that could lead to the revaluation of vacancy concentration at high temperatures, (ii) suggest that dumbbell interstitials play a major role in the melting mechanism of monatomic metallic crystals and (iii) support a new avenue for in-depth understanding of glassy metals. PMID:27143564

  6. Experimental evidence for thermal generation of interstitials in a metallic crystal near the melting temperature

    NASA Astrophysics Data System (ADS)

    Safonova, E. V.; Mitrofanov, Yu P.; Konchakov, R. A.; Vinogradov, A. Yu; Kobelev, N. P.; Khonik, V. A.

    2016-06-01

    The only intrinsic point defects of simple crystalline metals known from solid state physics are vacancies and interstitials. It is widely believed that while vacancies play a major role in crystal properties and their concentration reaches relatively big values near the melting temperature T m, interstitials essentially do not occur in thermodynamic equilibrium and their influence on properties is minor. Here, taking aluminum single crystals as an example, we present compelling experimental evidence for rapid thermoactivated growth of interstitial concentration upon approaching T m. Using high precision measurements of the shear modulus we found a diaelastic effect of up to -1.5% near T m. It is argued that this effect is mostly due to the generation of dumbbell (split) interstitials. The interstitial concentration c i rapidly increases upon approaching T m and becomes only 2–3 times smaller than that of vacancies just below T m. The reason for this c i -increase is conditioned by a decrease of the Gibbs free energy with temperature, which in turn originates from the high formation entropy of dumbbell interstitials and a decrease of their formation enthalpy at high c i . Special molecular dynamic simulation confirmed all basic aspects of the proposed interpretation. The results obtained (i) demonstrate the significance of interstitial concentration near T m that could lead to the revaluation of vacancy concentration at high temperatures, (ii) suggest that dumbbell interstitials play a major role in the melting mechanism of monatomic metallic crystals and (iii) support a new avenue for in-depth understanding of glassy metals.

  7. 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

  8. 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

  9. Metal accumulation capacity of five species of Sphagnum moss

    SciTech Connect

    Aulio, K.

    1985-10-01

    The present paper describes the first experimental evidence of the species-specific differences in the cation accumulation properties in Sphagnum mosses. Manganese was chosen for the object of the experiments because this element appears to show the greatest variability under natural conditions.

  10. 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…

  11. 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

  12. Experimental evidence for asymmetric mate preference and aggression: behavioral interactions in a woodrat (Neotoma) hybrid zone

    PubMed Central

    2013-01-01

    Background Female mate preferences may be under strong selection in zones of contact between closely related species because of greater variation in available mates and the potential costs of hybridization. We studied female mate preferences experimentally in a zone of secondary contact between Desert and Bryant’s Woodrat (Neotoma lepida and N. bryanti) in the southern foothills of the Sierra Nevada of California. We tested female preference for conspecific versus heterospecific males in paired choice trials in which females could interact freely with males, but males could not interact directly with each other. We compared preferences of females from both allopatric and sympatric sites. Results We did not find evidence of the process of reinforcement as assortative preferences were not stronger in sympatry than in allopatry. Mate preferences, however, were asymmetric, with N. lepida females mating preferentially with conspecifics and N. bryanti females showing no preference by species. Sympatric females were less likely to mate than allopatric females, due in part to an increase in aggressive interactions. However, even in the absence of aggression, courtship led to mating less often in sympatric females, suggesting they were choosier or had lower sexual motivation than allopatric females. Conclusions Patterns of mate choice in this woodrat system appear to be strongly impacted by body size and aggressive behavior. In particular, females of the smaller-bodied species rarely interact with the relatively large heterospecific males. In contrast females of the larger-bodied species accept the relatively small heterospecific males. For sympatric animals, rates of aggression were markedly higher than for allopatric animals and reduced affiliative and reproductive behavior in our trials. Sympatric animals are larger and more aggressive, traits that are likely under strong ecological selection across the sharp resource gradient that characterizes the contact zone

  13. Rare Earth Element - Humic Acid Interaction: Experimental Evidence for Kinetic and Equilibrium Fractionation in Aqueous Systems.

    NASA Astrophysics Data System (ADS)

    Sonke, J. E.; Salters, V. J.; Benedetti, M. F.

    2003-12-01

    Dissolved organic matter (DOM) is well known for it's strong binding capacity for trace metals. In order to better predict the role of DOM in the speciation and transport of trace metals in the environment we coupled capillary electrophoresis (CE), a molecular separation technique, to a Sector Field Inductively Coupled Plasma Mass Spectrometer (SF-ICP-MS). The combination of these two techniques allows for the study of non-labile metal speciation in aquatic samples. By separating Rare Earth Element (REE) complexes with EDTA and Humic Acid's (i.e. ligand competition) we have been able to determine conditional equilibrium binding constants (Kc) and kinetic rate constants for all 14 REE's with Humic (HA) and Fulvic Acids (FA) as a function of pH (6-9) and ionic strength (IS, 0.01-0.1 mol/L). Assuming a 1:1 binding mechanism, logKc values for REE-FA varied from 9.0 (La) to 10.5 (Lu) at pH 6, 0.1 mol/L IS, and 11.7 (La) to 14.6 (Lu) at pH 9, 0.1 mol/L IS. LogKc values for REE-HA were 10.6 (La) to 12.2 (Lu) at pH 6, 0.1 mol/L IS and 13.2 (La) to 16.5 (Lu) at pH 9, 0.1 mol/L IS. Slightly higher values for Kc were obtained at 0.01 mol/L IS. The general observations of stronger REE-HA binding compared to REE-FA, and stronger binding with increasing pH and decreasing IS correlate with our current understanding of metal-DOM interactions (1). Both Kc's as well as kinetic rate constants increase with increasing REE mass number (decreasing ionic radius); a reflection of the well-known lanthanide contraction. This is the first comprehensive metal binding dataset between REE and DOM, and the first experimental evidence for differential equilibrium and kinetic binding behavior between REE's and DOM. The 30-1000 fold increase in binding strength of heavy REE's with DOM provides for a an equilibrium fractionation mechanism that may explain features of the global geochemical REE cycle such as fractionation related to weathering, estuarine mixing, and REE scavenging in the deep ocean

  14. Chemopreventive properties of 3,3'-diindolylmethane in breast cancer: evidence from experimental and human studies.

    PubMed

    Thomson, Cynthia A; Ho, Emily; Strom, Meghan B

    2016-07-01

    Diet is a modifiable factor associated with the risk of several cancers, with convincing evidence showing a link between diet and breast cancer. The role of bioactive compounds of food origin, including those found in cruciferous vegetables, is an active area of research in cancer chemoprevention. This review focuses on 3,3'-diindolylmethane (DIM), the major bioactive indole in crucifers. Research of the cancer-preventive activity of DIM has yielded basic mechanistic, animal, and human trial data. Further, this body of evidence is largely supported by observational studies. Bioactive DIM has demonstrated chemopreventive activity in all stages of breast cancer carcinogenesis. This review describes current evidence related to the metabolism and mechanisms of DIM involved in the prevention of breast cancer. Importantly, this review also focuses on current evidence from human observational and intervention trials that have contributed to a greater understanding of exposure estimates that will inform recommendations for DIM intake. PMID:27261275

  15. 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.

  16. Towards the evidence of a purely spatial Einstein-Podolsky-Rosen paradox in images: measurement scheme and first experimental results

    NASA Astrophysics Data System (ADS)

    Devaux, F.; Mougin-Sisini, J.; Moreau, P. A.; Lantz, E.

    2012-07-01

    We propose a scheme to evidence the Einstein-Podolsky-Rosen (EPR) paradox for photons produced by spontaneous down conversion, from measurement of purely spatial correlations of photon positions both in the near- and in the far-field. Experimentally, quantum correlations have been measured in the far-field of parametric fluorescence created in a type II BBO crystal. Imaging is performed in the photon counting regime with an electron-multiplying CCD (EMCCD) camera.

  17. 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.

  18. 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.

  19. 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

  20. Accumulate Repeat Accumulate Coded Modulation

    NASA Technical Reports Server (NTRS)

    Abbasfar, Aliazam; Divsalar, Dariush; Yao, Kung

    2004-01-01

    In this paper we propose an innovative coded modulation scheme called 'Accumulate Repeat Accumulate Coded Modulation' (ARA coded modulation). This class of codes can be viewed as serial turbo-like codes, or as a subclass of Low Density Parity Check (LDPC) codes that are combined with high level modulation. Thus at the decoder belief propagation can be used for iterative decoding of ARA coded modulation on a graph, provided a demapper transforms the received in-phase and quadrature samples to reliability of the bits.

  1. Experimental and theoretical evidence for the chaotic dynamics of complex structures

    NASA Astrophysics Data System (ADS)

    Agop, M.; Dimitriu, D. G.; Niculescu, O.; Poll, E.; Radu, V.

    2013-04-01

    This paper presents the experimental results on the formation, dynamics and evolution towards chaos of complex space charge structures that emerge in front of a positively biased electrode immersed in a quiescent plasma. In certain experimental conditions, we managed to obtain the so-called multiple double layers (MDLs) with non-concentric configuration. Our experiments show that the interactions between each MDL's constituent entities are held responsible for the complex dynamics and eventually for its transition to chaos through cascades of spatio-temporal sub-harmonic bifurcations. Further, we build a theoretical model based on the fractal approximation (scale relativity theory) in order to reproduce the experimental results (plasma self-structuring and scenario of evolution to chaos). Comparing the experimental results with the theoretical ones, we observe a good correlation between them.

  2. Acceleration of large active earthflows triggered by massive snow accumulation events: evidences from monitoring the Corvara landslide in early 2014 (Dolomites, Italy)

    NASA Astrophysics Data System (ADS)

    Corsini, Alessandro; Mulas, Marco; Marcato, Gianluca; Chinellato, Giulia; Mair, Volkmar

    2015-04-01

    In the Dolomites of Italy, snowfall during winter 2013/2014 was exceptionally abundant. Major snowfall events occurred from late December 2013 to mid-March 2014. Snow accumulation in Badia Valley peaked in early February: from 2 to 4 meters with a positive gradient respect to altimetry and accordingly to wind accumulation zones. Below 2000 m asl, due to the mild temperatures recorded before the onset of snowfall, the relatively dry snow cover was mostly deposited on top of unfrozen soils. The Corvara landslide is a large active earthflow located close to Corvara in Badia, at an elevation from 2000 to 1600 m. It's displacement rate before, during and after the exceptional snowfall period was monitored at high temporal frequency. Surface displacement was measured bi-weekly by differential GPS in several benchmarks in the source, track and accumulation zone. Deep displacement was monitored semi-continuously by two in-place inclinometers at 48 m depth in the accumulation zone, across the main deep-seated sliding surface. Results show an acceleration of movements, both at surface and at depth, soon after the massive snow accumulation event of 31st January to 2nd February 2014, which suddenly increased snow thickness from 1 to more than 2 metres. Short time lags between the onset of the acceleration of movements in the source, the track and the accumulation zones were also recorded. The landslide then maintained a relatively constant velocity during the high snow cover period extended to earlyApril and underwent a progressive deceleration during the snowmelt period that lasted until mid-June. The fact that the acceleration of the Corvara earthflow was triggered by a massive and rapid snow accumulation event, provides a quite different perspective from the generally adopted one that considers the destabilizing effect of snow only in relation to the increase of groundwater level during rapid snowmelt. A full explanation of the processes associated to the dynamics observed

  3. Evidence for a resonant cyclotron interaction between runaway electrons and MHD modes in the experimental advanced superconducting tokamak

    SciTech Connect

    Li Erzhong; Zhou Ruijie; Hu Liqun

    2011-09-15

    In the past, the resonant cyclotron interaction between runaway electrons and lower hybrid waves via anomalous Doppler broadening was experimentally investigated, and it was shown to be able to create a barrier to the energy that could be reached by the runaway electrons [E. Li et al., Nucl. Instrum. Methods Phys. Res. A 621, 566 (2010)]. In this paper, to our knowledge for the first time, experimental evidence will be provided for a resonant cyclotron interaction between runaway electrons and magnetohydrodynamics modes in a stochastic magnetic field in the experimental advanced superconducting tokamak (EAST), which has been theoretically proposed as a mechanism able to limit the maximum attainable energy by runaway electrons in tokamak plasmas [J. R. Martin-Solis and R. Sanchez, Phys. Plasmas 15, 112505 (2008)].

  4. 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…

  5. 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…

  6. 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…

  7. 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…

  8. 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…

  9. 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…

  10. Do Child Development Accounts Promote Account Holding, Saving, and Asset Accumulation for Children's Future? Evidence from a Statewide Randomized Experiment

    ERIC Educational Resources Information Center

    Nam, Yunju; Kim, Youngmi; Clancy, Margaret; Zager, Robert; Sherraden, Michael

    2013-01-01

    This study examines the impacts of Child Development Accounts (CDAs) on account holding, saving, and asset accumulation for children, using data from the SEED for Oklahoma Kids experiment (SEED OK). SEED OK, a policy test of universal and progressive CDAs, provides a 529 college savings plan account to every infant in the treatment group with…

  11. Experimental evidence for the interplay between individual wealth and transaction network

    NASA Astrophysics Data System (ADS)

    Tseng, J.-J.; Li, S.-P.; Wang, S.-C.

    2010-01-01

    We conduct a market experiment with human agents in order to explore the structure of transaction networks and to study the dynamics of wealth accumulation. The experiment is carried out on our platform for 97 days with 2,095 effective participants and 16,936 times of transactions. From these data, the hybrid distribution (log-normal bulk and power-law tail) in the wealth is observed and we demonstrate that the transaction networks in our market are always scale-free and disassortative even for those with the size of the order of few hundred. We further discover that the individual wealth is correlated with its degree by a power-law function which allows us to relate the exponent of the transaction network degree distribution to the Pareto index in wealth distribution.

  12. 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

  13. 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. PMID:25702687

  14. Experimental evidence for therapeutic potential of taurine in the treatment of nonalcoholic fatty liver disease

    PubMed Central

    Gentile, Christopher L.; Nivala, Angela M.; Gonzales, Jon C.; Pfaffenbach, Kyle T.; Wang, Dong; Wei, Yuren; Jiang, Hua; Orlicky, David J.; Petersen, Dennis R.; Maclean, Kenneth N.

    2011-01-01

    The incidence of obesity is now at epidemic proportions and has resulted in the emergence of nonalcoholic fatty liver disease (NAFLD) as a common metabolic disorder that can lead to liver injury and cirrhosis. Excess sucrose and long-chain saturated fatty acids in the diet may play a role in the development and progression of NAFLD. One factor linking sucrose and saturated fatty acids to liver damage is dysfunction of the endoplasmic reticulum (ER). Although there is currently no proven, effective therapy for NAFLD, the amino sulfonic acid taurine is protective against various metabolic disturbances, including alcohol-induced liver damage. The present study was undertaken to evaluate the therapeutic potential of taurine to serve as a preventative treatment for diet-induced NAFLD. We report that taurine significantly mitigated palmitate-mediated caspase-3 activity, cell death, ER stress, and oxidative stress in H4IIE liver cells and primary hepatocytes. In rats fed a high-sucrose diet, dietary taurine supplementation significantly reduced hepatic lipid accumulation, liver injury, inflammation, plasma triglycerides, and insulin levels. The high-sucrose diet resulted in an induction of multiple components of the unfolded protein response in the liver consistent with ER stress, which was ameliorated by taurine supplementation. Treatment of mice with the ER stress-inducing agent tunicamycin resulted in liver injury, unfolded protein response induction, and hepatic lipid accumulation that was significantly ameliorated by dietary supplementation with taurine. Our results indicate that dietary supplementation with taurine offers significant potential as a preventative treatment for NAFLD. PMID:21957160

  15. 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. PMID:27217250

  16. Experimental evidence of the theoretical spatial frequency response of cubic phase mask wavefront coding imaging systems.

    PubMed

    Somayaji, Manjunath; Bhakta, Vikrant R; Christensen, Marc P

    2012-01-16

    The optical transfer function of a cubic phase mask wavefront coding imaging system is experimentally measured across the entire range of defocus values encompassing the system's functional limits. The results are compared against mathematical expressions describing the spatial frequency response of these computational imagers. Experimental data shows that the observed modulation and phase transfer functions, available spatial frequency bandwidth and design range of this imaging system strongly agree with previously published mathematical analyses. An imaging system characterization application is also presented wherein it is shown that the phase transfer function is more robust than the modulation transfer function in estimating the strength of the cubic phase mask. PMID:22274533

  17. An experimental evidence-based computational paradigm for new logic-gates in neuronal activity

    NASA Astrophysics Data System (ADS)

    Vardi, R.; Guberman, S.; Goldental, A.; Kanter, I.

    2013-09-01

    We propose a new experimentally corroborated paradigm in which the functionality of the brain's logic-gates depends on the history of their activity, e.g. an OR-gate that turns into a XOR-gate over time. Our results are based on an experimental procedure where conditioned stimulations were enforced on circuits of neurons embedded within a large-scale network of cortical cells in vitro. The underlying biological mechanism is the unavoidable increase of neuronal response latency to ongoing stimulations, which imposes a non-uniform gradual stretching of network delays.

  18. 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.

  19. 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. PMID:20302425

  20. 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

  1. 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.

  2. Oxytocin and Major Depressive Disorder: Experimental and Clinical Evidence for Links to Aetiology and Possible Treatment

    PubMed Central

    Slattery, David A.; Neumann, Inga D.

    2010-01-01

    Affective disorders represent the most common psychiatric diseases, with substantial co-morbidity existing between major depressive disorders (MDD) and anxiety disorders. The lack of truly novel acting compounds has led to non-monoaminergic based research and hypotheses in recent years. The large number of brain neuropeptides, characterized by discrete synthesis sites and multiple receptors, represent likely research candidates for novel therapeutic targets. The present review summarises the available preclinical and human evidence regarding the neuropeptide, oxytocin, and its implications in the aetiology and treatment of MDD. While the evidence is not conclusive at present additional studies are warranted to determine whether OXT may be of therapeutic benefit in subsets of MDD patients such as those with comorbid anxiety symptoms and low levels of social attachment.

  3. Teacher Pay for Performance: Experimental Evidence from the Project on Incentives in Teaching (POINT)

    ERIC Educational Resources Information Center

    Springer, Matthew G.; Ballou, Dale; Hamilton, Laura; Le, Vi-Nhuan; Lockwood, J. R.; McCaffrey, Daniel F.; Pepper, Matthew; Stecher, Brian M.

    2011-01-01

    This paper presents the results of a rigorous experiment examining the impact of pay for performance on student achievement and instructional practice. This study, conducted by the National Center on Performance Incentives in partnership with the RAND Corporation examines an experimental pay for performance program administered via a randomized…

  4. 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…

  5. 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…

  6. 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…

  7. EVIDENCE FOR EFFECTS OF CHRONIC LEAD EXPOSURE ON BLOOD PRESSURE IN EXPERIMENTAL ANIMALS: AN OVERVIEW

    EPA Science Inventory

    Information obtained in a number of experimental studies conducted over the last forty years on the effects of lead on blood pressure is reviewed. Differences in animal species, age at beginning of exposure, level of lead exposure, indices of lead burden, and blood pressure effec...

  8. 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…

  9. Experimental Evidence for Dynamic Social Impact: The Emergence of Subcultures in Electronic Groups.

    ERIC Educational Resources Information Center

    Latane, Bibb; Bourgeois, Martin J.

    1996-01-01

    Presents results of experimental tests of Dynamic Social Impact Theory (DSIT) in which participants engaged in discussions over electronic mail. Finds support for the emergence of four group phenomena predicted by DSIT. Shows how, rewarded for being in the majority, individuals' choices resulted in the emergence of four forms of group level…

  10. Work Towards Experimental Evidence Of Hard X-Ray Photoionization In Highly Charged Krypton

    SciTech Connect

    Silver, E.; Brickhouse, N. S.; Kirby, K.; Lin, T.; Gillaspy, J. D.; Gokhale, P.; Kanter, E. P.; Dunford, R. W.; Seifert, S.; Young, L.; McDonald, J.; Schneider, D.

    2011-06-01

    Ions of almost any charge state can be produced through electron-impact ionization. Here we describe our first experiments designed to photoionize these highly charged ions with hard x-rays by pairing an electron and photon beam. A spectral line at 12.7(1) keV with an intensity corroborated by theory may be the first evidence of hard x-ray photoionization of a highly charged ion.

  11. Work toward experimental evidence of hard x-ray photoionization in highly charged krypton.

    SciTech Connect

    Silver, E.; Gillaspy, J.D.; Gokhale, P.; Kanter, E.P.; Brickhouse, N.S.; Dunford, R.W.; Kirby, K.; Lin, T.; McDonald, J.; Schneider, D.; Seifert, S.; Young, L.

    2011-06-01

    Ions of almost any charge state can be produced through electron-impact ionization. Here we describe our first experiments designed to photoionize these highly charged ions with hard x-rays by pairing an electron and photon beam. A spectral line at 12.7(1) keV with an intensity corroborated by theory may be the first evidence of hard x-ray photoionization of a highly charged ion.

  12. Experimental evidence of resonant tunneling via localized DQW states in an asymmetric triple barrier structure

    NASA Astrophysics Data System (ADS)

    Velásquez, Rober

    2003-04-01

    In this work we report on field-induced features appearing in the tunneling current traces of a biased asymmetric triple barrier resonant tunneling device in the presence of an in-plane magnetic field. A theoretical model that satisfactorily explains the origin of these features is discussed. The reported data evidences the localized nature of the quantum states in thin layer asymmetric double-quantum-well structures.

  13. Exploring Effective Strategies for Increasing the Amount of Moderate-to-Vigorous Physical Activity Children Accumulate during Recess: A Quasi-Experimental Intervention Study

    ERIC Educational Resources Information Center

    Efrat, Merav W.

    2013-01-01

    Background: Less than half of elementary children meet the physical activity recommendations of 30 to 60 minutes of moderate-to-vigorous physical activity (MVPA) on a daily basis. Recess provides the single biggest opportunity for children to accumulate MVPA. This study explored whether a teacher's social prompting to be active during recess…

  14. Ground penetrating radar (GPR) evidence for variations in free phase carbon gas accumulation as a function of peatland landforms: a comparison between near-crest bogs and mid-slope lawns

    NASA Astrophysics Data System (ADS)

    Parsekian, A.; Slater, L.; Comas, X.; Nolan, J.; Glaser, P.

    2009-05-01

    Northern peatlands serve as atmospheric sources of biogenic free-phase gas (FPG) produced under anaerobic conditions below the water table (mostly methane and carbon dioxide). Recent evidence suggest that FPG accumulates in the subsurface under confining layers and is released during sudden ebullition events, often triggered by sudden drops in atmospheric pressure. Accurate quantification of the impact of FPG releases on the global carbon budget is needed given recent observations of increasing atmospheric methane concentrations. One important step towards understanding the dynamics of FPG in peatlands is to investigate whether certain peatland landforms (i.e. areas with significantly different vegetation patterns) may be more conducive to FPG accumulation and/or release. Additionally, it is important to determine the vertical distribution of FPG within the peat soil and the potential role of peat stratigraphy on gas accumulation and release. In this study, we used common mid-point (CMP) velocity surveys to predict vertical profiles of FPG accumulations by comparing two different peatland landforms: historically forested near-crest bogs and non- forested mid-slope lawns in the Glacial Lake Agassiz Peatland of Minnesota, USA. We show that there is a statistically significant difference in electromagnetic (EM) wave velocities calculated over gas-rich intervals in the peat strata compared to gas-poor intervals. Common-offset radar profiles identified laterally continuous woody confining layers responsible for FPG accumulation. Chaotic GPR facies containing diffraction hyperbolae at the forested near-crest sites are interpreted as deformation of the peat matrix due to FPG accumulation and/or peat fabric disturbance during FPG release events. In contrast, non-forested mid-slope lawn sites, are characterized by planar GPR facies with no evidence of peat fabric disturbance and small relative changes in interpreted EM velocity distribution along the peat column. Using the

  15. Regulation of myofibrillar accumulation in chick muscle cultures - Evidence for the involvement of calcium and lysosomes in non-uniform turnover of contractile proteins

    NASA Technical Reports Server (NTRS)

    Silver, Geri; Etlinger, Joseph D.

    1985-01-01

    The effects of calcium on the synthesis and the degradation of individual myofibrillar proteins were investigated using primary chick-leg skeletal muscle cultures labeled with S-35-methionine (for protein accumulation experiments) or Ca(2+)-45 (for calcium efflux experiments). It was found that the turnover of individual contractile proteins is regulated nonuniformly by a calcium-dependent mechanism involving lysosomes. The results also indicate that contractile proteins are released from the myofibril before their breakdown to amino acids.

  16. Noise Reduction by Signal Accumulation

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2006-01-01

    The aim of this paper is to show how the noise reduction by signal accumulation can be accomplished with a data acquisition system. This topic can be used for student projects. In many cases, the noise reduction is an unavoidable part of experimentation. Several techniques are known for this purpose, and among them the signal accumulation is the…

  17. 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

  18. 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.

  19. Experimental evidence of Xe incorporation in Schottky defects in UO2

    NASA Astrophysics Data System (ADS)

    Bès, René; Martin, Philippe; Vathonne, Emerson; Delorme, Rémy; Sabathier, Catherine; Freyss, Michel; Bertolus, Marjorie; Glatzel, Pieter

    2015-03-01

    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.

  20. 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.

  1. 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.

  2. Investigation of a model vertical motion liquid damper: comparing numerical simulation and experimental evidence

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Chris; Tabatabai, Habib; Buechel, Craig

    2005-05-01

    Tuned Liquid Dampers (TLD) are used to limit horizontal vibrations in structures, and offer practical alternatives to Tuned Mass Dampers (TMD). However, to our knowledge, liquid damping systems have not been developed to reduce vertical vibrations. In this work, we develop a model for a Vertical Motion Liquid Damper (VMLD), idealized as a discrete, two degree of freedom system. One degree of freedom represents the 'target' structure that is to be damped, and the other represents the approximate, one-dimensional motion of a liquid in a U-shaped tube. Internal losses due to the fluid oscillation serve to limit and control motions of the target structure. The U-shaped tube has a flexible joint such that one vertical portion and the horizontal portion of the tube remain fixed, and the remaining vertical portion of the tube is affixed to the vibrating structure, allowing the liquid to become excited. The equations of motion are derived using Lagrange's Equations, and are integrated using Runge-Kutta algorithms that are available in Matlab. An experimental model was built in the laboratory, consisting of a mass attached to the end of a cantilevered beam (corresponding to the target structure), and a U-tube made from PVC pipe. The various damping and stiffness parameters of the system were calibrated independently based on experimental data. Measured data from the experimental model show reasonable agreement with numerical simulations.

  3. 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. PMID:26236847

  4. 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.

  5. 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). PMID:25597157

  6. Infiltration on sloping surfaces: Laboratory experimental evidence and implications for infiltration modeling

    NASA Astrophysics Data System (ADS)

    Morbidelli, Renato; Saltalippi, Carla; Flammini, Alessia; Cifrodelli, Marco; Corradini, Corrado; Govindaraju, Rao S.

    2015-04-01

    Infiltration on sloping surfaces occupies an important role in our understanding of surface and subsurface hydrology. Previous studies have provided conflicting results about the role of slope on infiltration. Here, our main objective is to highlight, by well-controlled experiments, the slope role in the absence of the conflicting contributions generated by other physical processes observed in previous studies under natural or laboratory conditions. The experimental program was designed to resolve some of the confounding factors such as lower impermeable boundary condition, range of rainfall rates relative to soil saturated hydraulic conductivity, surface sealing, and erosion of top soil. The experimental apparatus consists of a box containing a natural bare soil with slope angle γ chosen between 0° and 10°, two sensors of surface and deep flow, one probe for moisture content and an artificial rainfall generator. The primary experimental results suggest that under steady conditions and rainfall rate, r, greater than saturated hydraulic conductivity, Ks, the deep flow, Qd, decreases with increasing slope angle, γ, up to a value leading to Qd(γ = 1°)/Qd(γ = 10°) equal to ≈4 which is in contrast with the results provided in a few earlier papers. Furthermore, in sloping bare soils surface runoff is produced even for r < Ks. Finally, we discuss the link between Qd(γ) and the shear stress at the soil surface as a guideline in the determination of an effective saturated hydraulic conductivity to be incorporated in the existing horizontal infiltration models.

  7. 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. PMID:27255494

  8. 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

  9. Theoretical approaches and experimental evidence for liquid-vapor phase transitions in nuclei

    SciTech Connect

    Moretto, L.G.; Elliott, J.B.; Phair, L.; Wozniak, G.J.; Mader, C.M.; Chappars, A.

    2001-01-01

    The leptodermous approximation is applied to nuclear systems for T > 0. The introduction of surface corrections leads to anomalous caloric curves and to negative heat capacities in the liquid-gas coexistence region. Clusterization in the vapor is described by associating surface energy to clusters according to Fisher's formula. The three-dimensional Ising model, a leptodermous system par excellence, does obey rigorously Fisher's scaling up to the critical point. Multifragmentation data from several experiments including the ISiS and EOS Collaborations, as well as compound nucleus fragment emission at much lower energy follow the same scaling, thus providing the strongest evidence yet of liquid-vapor coexistence.

  10. Experimental evidence for self-organized criticality in tokamak plasma turbulence

    NASA Astrophysics Data System (ADS)

    Rhodes, T. L.; Moyer, R. A.; Groebner, R.; Doyle, E. J.; Lehmer, R.; Peebles, W. A.; Rettig, C. L.

    1999-03-01

    Measurements of plasma turbulence spectra and particle flux from the DIII-D tokamak exhibit significant agreement with predictions of self-organized criticality (SOC) modeling. Power spectra of density ñ, potential g˜f, and particle flux Γ, are observed to have three regions of frequency dependence: f0, f-1 and f-4. In addition, the particle flux probability distribution displays a Γ-1 scaling over two decades in Γ. These results provide the first evidence that the plasma is in a state consistent with SOC models and place a constraint on plasma transport models.

  11. Experimental Evidence for a Light and Broad Scalar Resonance in D+ --> π-π+π+ Decay

    NASA Astrophysics Data System (ADS)

    Aitala, E. M.; Amato, S.; Anjos, J. C.; Appel, J. A.; Ashery, D.; Banerjee, S.; Bediaga, I.; Blaylock, G.; Bracker, S. B.; Burchat, P. R.; Burnstein, R. A.; Carter, T.; Carvalho, H. S.; Copty, N. K.; Cremaldi, L. M.; Darling, C.; Denisenko, K.; Devmal, S.; Fernandez, A.; Fox, G. F.; Gagnon, P.; Gobel, C.; Gounder, K.; Halling, A. M.; Herrera, G.; Hurvits, G.; James, C.; Kasper, P. A.; Kwan, S.; Langs, D. C.; Leslie, J.; Lundberg, B.; Magnin, J.; Massafferri, A.; Maytal-Beck, S.; Meadows, B.; de Mello Neto, J. R.; Mihalcea, D.; Milburn, R. H.; de Miranda, J. M.; Napier, A.; Nguyen, A.; D'Oliveira, A. B.; O'Shaughnessy, K.; Peng, K. C.; Perera, L. P.; Purohit, M. V.; Quinn, B.; Radeztsky, S.; Rafatian, A.; Reay, N. W.; Reidy, J. J.; Dos Reis, A. C.; Rubin, H. A.; Sanders, D. A.; Santha, A. K.; Santoro, A. F.; Schwartz, A. J.; Sheaff, M.; Sidwell, R. A.; Slaughter, A. J.; Sokoloff, M. D.; Solano, J.; Stanton, N. R.; Stefanski, R. J.; Stenson, K.; Summers, D. J.; Takach, S.; Thorne, K.; Tripathi, A. K.; Watanabe, S.; Weiss-Babai, R.; Wiener, J.; Witchey, N.; Wolin, E.; Yang, S. M.; Yi, D.; Yoshida, S.; Zaliznyak, R.; Zhang, C.

    2001-01-01

    From a sample of 1172+/-61 D+-->π-π+π+ decays, we find γ\\(D+-->π- π+π+\\)/γ\\(D+-->K-π+π+\\) = 0.0311+/-0.0018+0.0016-0.0026. Using a coherent amplitude analysis to fit the Dalitz plot of these decays, we find strong evidence that a scalar resonance of mass 478+24-23+/-17 MeV/c2 and width 324+42-40+/-21 MeV/c2 accounts for approximately half of all decays.

  12. Experimental evidence for convergent evolution of maternal care heuristics in industrialized and small-scale populations

    PubMed Central

    Kushnick, Geoff; Hanowell, Ben; Kim, Jun-Hong; Langstieh, Banrida; Magnano, Vittorio; Oláh, Katalin

    2015-01-01

    Maternal care decision rules should evolve responsiveness to factors impinging on the fitness pay-offs of care. Because the caretaking environments common in industrialized and small-scale societies vary in predictable ways, we hypothesize that heuristics guiding maternal behaviour will also differ between these two types of populations. We used a factorial vignette experiment to elicit third-party judgements about likely caretaking decisions of a hypothetical mother and her child when various fitness-relevant factors (maternal age and access to resources, and offspring age, sex and quality) were varied systematically in seven populations—three industrialized and four small-scale. Despite considerable variation in responses, we found that three of five main effects, and the two severity effects, exhibited statistically significant industrialized/ small-scale population differences. All differences could be explained as adaptive solutions to industrialized versus small-scale caretaking environments. Further, we found gradients in the relationship between the population-specific estimates and national-level socio-economic indicators, further implicating important aspects of the variation in industrialized and small-scale caretaking environments in shaping heuristics. Although there is mounting evidence for a genetic component to human maternal behaviour, there is no current evidence for interpopulation variation in candidate genes. We nonetheless suggest that heuristics guiding maternal behaviour in diverse societies emerge via convergent evolution in response to similar selective pressures. PMID:26543577

  13. 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

  14. 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.

  15. Experimental evidence for convergent evolution of maternal care heuristics in industrialized and small-scale populations.

    PubMed

    Kushnick, Geoff; Hanowell, Ben; Kim, Jun-Hong; Langstieh, Banrida; Magnano, Vittorio; Oláh, Katalin

    2015-06-01

    Maternal care decision rules should evolve responsiveness to factors impinging on the fitness pay-offs of care. Because the caretaking environments common in industrialized and small-scale societies vary in predictable ways, we hypothesize that heuristics guiding maternal behaviour will also differ between these two types of populations. We used a factorial vignette experiment to elicit third-party judgements about likely caretaking decisions of a hypothetical mother and her child when various fitness-relevant factors (maternal age and access to resources, and offspring age, sex and quality) were varied systematically in seven populations-three industrialized and four small-scale. Despite considerable variation in responses, we found that three of five main effects, and the two severity effects, exhibited statistically significant industrialized/ small-scale population differences. All differences could be explained as adaptive solutions to industrialized versus small-scale caretaking environments. Further, we found gradients in the relationship between the population-specific estimates and national-level socio-economic indicators, further implicating important aspects of the variation in industrialized and small-scale caretaking environments in shaping heuristics. Although there is mounting evidence for a genetic component to human maternal behaviour, there is no current evidence for interpopulation variation in candidate genes. We nonetheless suggest that heuristics guiding maternal behaviour in diverse societies emerge via convergent evolution in response to similar selective pressures. PMID:26543577

  16. Effects of Bisphenol A on ion channels: Experimental evidence and molecular mechanisms.

    PubMed

    Soriano, Sergi; Ripoll, Cristina; Alonso-Magdalena, Paloma; Fuentes, Esther; Quesada, Ivan; Nadal, Angel; Martinez-Pinna, Juan

    2016-07-01

    Bisphenol A (BPA) is an endocrine-disrupting chemical (EDC) produced in huge quantities in the manufacture of polycarbonate plastics and epoxy resins. It is present in most humans in developed countries, acting as a xenoestrogen and it is considered an environmental risk factor associated to several diseases. Among the whole array of identified mechanisms by which BPA can interfere with physiological processes in living organisms, changes on ion channel activity is one of the most poorly understood. There is still little evidence about BPA regulation of ion channel expression and function. However, this information is key to understand how BPA disrupts excitable and non-excitable cells, including neurons, endocrine cells and muscle cells. This report is the result of a comprehensive literature review on the effects of BPA on ion channels. We conclude that there is evidence to say that these important molecules may be key end-points for EDCs acting as xenoestrogens. However, more research on channel-mediated BPA effects is needed. Particularly, mechanistic studies to unravel the pathophysiological actions of BPA on ion channels at environmentally relevant doses. PMID:26930576

  17. Renin-angiotensin system as a potential therapeutic target in stroke and retinopathy: experimental and clinical evidence.

    PubMed

    Fouda, Abdelrahman Y; Artham, Sandeep; El-Remessy, Azza B; Fagan, Susan C

    2016-02-01

    As our knowledge expands, it is now clear that the renin-angiotensin (Ang) system (RAS) mediates functions other than regulating blood pressure (BP). The RAS plays a central role in the pathophysiology of different neurovascular unit disorders including stroke and retinopathy. Moreover, the beneficial actions of RAS modulation in brain and retina have been documented in experimental research, but not yet exploited clinically. The RAS is a complex system with distinct yet interconnected components. Understanding the different RAS components and their functions under brain and retinal pathological conditions is crucial to reap their benefits. The aim of the present review is to provide an experimental and clinical update on the role of RAS in the pathophysiology and treatment of stroke and retinopathy. Combining the evidence from both these disorders allows a unique opportunity to move both fields forward. PMID:26769658

  18. Experimental Study on Basic Shape of Simple Device for Prevention of Inflow and Accumulation of Buoyant Refuse at the Intake of Headworks

    NASA Astrophysics Data System (ADS)

    Namihira, Atsushi; Kobayashi, Hiroyasu; Takaki, Kyoji; Goto, Masahiro

    In this research, the basic shape of the device for prevention of inflow and accumulation of buoyant refuse at the intake of headworks is investigated by hydraulic model test. As results, it is clarified that an enough result is not obtained if the prismatic bar that floats on the water is set as the device for prevention so that it may cross the intake. On the other hands, it is clarified that the inflow and accumulation of buoyant refuse at the intake is decreased greatly if the bar is set so that it may be diagonally thrust out from the upstream edge of the intake to the downstream on the river side. In this case, it is necessary to decide the length and setting angle of the bar so that it may intersect with the boundary line of the area where the refuse flow into the intake with no device for prevention.

  19. Agricultural wetlands as potential hotspots for mercury bioaccumulation: Experimental evidence using caged fish

    USGS Publications Warehouse

    Ackerman, J.T.; Eagles-Smith, C. A.

    2010-01-01

    Wetlands provide numerous ecosystem services, but also can be sources of methylmercury (MeHg) production and export. Rice agricultural wetlands in particular may be important sites for MeHg bioaccumulation due to their worldwide ubiquity, periodic flooding schedules, and high use by wildlife. We assessed MeHg bioaccumulation within agricultural and perennial wetlands common to California's Central Valley during summer, when the majority of wetland habitats are shallowly flooded rice fields. We introduced caged western mosquitofish (Gambusia affinis) within white rice (Oryza sativa), wild rice (Zizania palustris), and permanent wetlands at water inlets, centers, and outlets. Total mercury (THg) concentrations and body burdens in caged mosquitofish increased rapidly, exceeding baseline values at introduction by 135% to 1197% and 29% to 1566% among sites, respectively, after only 60 days. Mercury bioaccumulation in caged mosquitofish was greater in rice fields than in permanent wetlands, with THg concentrations at wetland outlets increasing by 12.1, 5.8, and 2.9 times over initial concentrations in white rice, wild rice, and permanent wetlands, respectively. In fact, mosquitofish caged at white rice outlets accumulated 721 ng Hg/fish in just 60 days. Mercury in wild mosquito fish and Mississippi silversides (Menidia audens) concurrently sampled at wetland outlets also were greater in white rice and wild rice than permanent wetlands. Within wetlands, THg concentrations and body burdens of both caged and wild fish increased from water inlets to outlets in white rice fields, and tended to not vary among sites in permanent wetlands. Fish THg concentrations in agricultural wetlands were high, exceeding 0.2 ??g/g ww in 82% of caged fish and 59% of wild fish. Our results indicate that shallowly flooded rice fields are potential hotspots for MeHg bioaccumulation and, due to their global prevalence, suggest that agricultural wetlands may be important contributors to Me

  20. Time-lag in extinction dynamics in experimental populations: evidence for a genetic Allee effect?

    PubMed

    Vercken, Elodie; Vincent, Flora; Mailleret, Ludovic; Ris, Nicolas; Tabone, Elisabeth; Fauvergue, Xavier

    2013-05-01

    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

  1. 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

  2. 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.

  3. 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

  4. Fayalite Oxidation Processes: Experimental Evidence for the Stability of Pure Ferric Fayalite?

    NASA Technical Reports Server (NTRS)

    Martin, A. M.; Righter, K.; Keller, L. P.; Medard, E.; Devouard, B.; Rahman, Z.

    2011-01-01

    Olivine is one of the most important minerals in Earth and planetary sciences. Fayalite Fe2(2+)SiO4, the ferrous end-member of olivine, is present in some terrestrial rocks and primitive meteorites (CV3 chondrites). A ferric fayalite (or ferri-fayalite), Fe(2+) Fe2(3+)(SiO4)2 laihunite, has been reported in Earth samples (magnetite ore, metamorphic and volcanic rocks...) and in Martian meteorites (nakhlites). Laihunite was also synthesized at 1 atmosphere between 400 and 700 C. We show evidence for the stability of a pure ferrifayalite end-member and for potential minerals with XFe(3+) between 2/3 and 1.

  5. Eliciting health care priorities in developing countries: experimental evidence from Guatemala.

    PubMed

    Font, Joan Costa; Forns, Joan Rovira; Sato, Azusa

    2016-02-01

    Although some methods for eliciting preferences to assist participatory priority setting in health care in developed countries are available, the same is not true for poor communities in developing countries whose preferences are neglected in health policy making. Existing methods grounded on self-interested, monetary valuations that may be inappropriate for developing country settings where community care is provided through 'social allocation' mechanisms. This paper proposes and examines an alternative methodology for eliciting preferences for health care programmes specifically catered for rural and less literate populations but which is still applicable in urban communities. Specifically, the method simulates a realistic collective budget allocation experiment, to be implemented in both rural and urban communities in Guatemala. We report evidence revealing that participatory budget-like experiments are incentive compatible mechanisms suitable for revealing collective preferences, while simultaneously having the advantage of involving communities in health care reform processes. PMID:25841770

  6. Rapid communication: experimental evidence that juvenile pelagic jacks (Carangidae) respond behaviorally to DMSP.

    PubMed

    Debose, Jennifer L; Nevitt, Gabrielle A; Dittman, Andrew H

    2010-03-01

    Dimethylsulfoniopropionate (DMSP) is produced by marine algae and released during foraging activity by zooplankton and fish. Pelagic fishes depend on patchily distributed foraging opportunities, and DMSP may be an important signaling molecule for these events. We have previously shown that the abundance of carangid jacks is positively associated with elevated DMSP levels over coral reefs in the Gulf of Mexico, suggesting that these fishes may use spatial and temporal variation in DMSP to locate foraging opportunities. Here, we extend this work by demonstrating that juveniles of two species of pelagic jack, crevalle jack, Caranx hippos, and bluefin trevally, C. melampygus, detect and respond to DMSP in a flow-through tank in the laboratory. Juveniles of these species showed elevated swimming activity in response to ecologically relevant concentrations of DMSP (10(-9) M). These results provide further evidence that this chemical may serve as a chemosensory cue for carangid species. PMID:20177745

  7. Experimental evidence showing that no mitotically active female germline progenitors exist in postnatal mouse ovaries

    PubMed Central

    Zhang, Hua; Zheng, Wenjing; Shen, Yan; Adhikari, Deepak; Ueno, Hiroo; Liu, Kui

    2012-01-01

    It has been generally accepted for more than half a century that, in most mammalian species, oocytes cannot renew themselves in postnatal or adult life, and that the number of oocytes is already fixed in fetal or neonatal ovaries. This assumption, however, has been challenged over the past decade. In this study, we have taken an endogenous genetic approach to this question and generated a multiple fluorescent Rosa26rbw/+;Ddx4-Cre germline reporter mouse model for in vivo and in vitro tracing of the development of female germline cell lineage. Through live cell imaging and de novo folliculogenesis experiments, we show that the Ddx4-expressing cells from postnatal mouse ovaries did not enter mitosis, nor did they contribute to oocytes during de novo folliculogenesis. Our results provide evidence that supports the traditional view that no postnatal follicular renewal occurs in mammals, and no mitotically active Ddx4-expressing female germline progenitors exist in postnatal mouse ovaries. PMID:22778414

  8. Evidence of experimental postcyclic transmission of Bothriocephalus acheilognathi in bonytail chub (Gila elegans)

    USGS Publications Warehouse

    Hansen, S.P.; Choudhury, A.; Cole, R.A.

    2007-01-01

    We examined the role that predation of infected conspecific fish and postcyclic transmission might play in the life cycle of the Asian fish tapeworm, Bothriocephalus acheilognathi (Cestoda: Pseudophyllidea) Yamaguti, 1934. Young-of-the-year (YOY) bonytail chub (Gila elegans) were exposed to copepods infected with B. acheilognathi and subsequently fed to subadult bonytail chub. Within 1 wk after consumption of the YOY chub, subadults were necropsied and found infected with gravid and nongravid tapeworms. This study provides evidence that postcyclic transfer of B. acheilognathi can occur. Postcyclic transmission may be an important life history trait of B. acheilognathi that merits consideration when studying the impact and distribution of this invasive and potentially pathogenic tapeworm. ?? American Society of Parasitologists 2007.

  9. Experimental evidence of vocal recognition in young and adult black-legged kittiwakes

    USGS Publications Warehouse

    Mulard, Hervé; Aubin, T.; White, J.F.; Hatch, Shyla A.; Danchin, E.

    2008-01-01

    Individual recognition is required in most social interactions, and its presence has been confirmed in many species. In birds, vocal cues appear to be a major component of recognition. Curiously, vocal recognition seems absent or limited in some highly social species such as the black-legged kittiwake, Rissa tridactyla. Using playback experiments, we found that kittiwake chicks recognized their parents vocally, this capacity being detectable as early as 20 days after hatching, the youngest age tested. Mates also recognized each other's long calls. Some birds reacted to their partner's voice when only a part of the long call was played back. Nevertheless, only about a third of the tested birds reacted to their mate's or parents' call and we were unable to detect recognition among neighbours. We discuss the low reactivity of kittiwakes in relation to their cliff-nesting habit and compare our results with evidence of vocal recognition in other larids. ?? 2008 The Association for the Study of Animal Behaviour.

  10. Sharks shape the geometry of a selfish seal herd: experimental evidence from seal decoys

    PubMed Central

    De Vos, Alta; O'Riain, M. Justin

    2010-01-01

    Many animals respond to predation risk by forming groups. Evolutionary explanations for group formation in previously ungrouped, but loosely associated prey have typically evoked the selfish herd hypothesis. However, despite over 600 studies across a diverse array of taxa, the critical assumptions of this hypothesis have remained collectively untested, owing to several confounding problems in real predator–prey systems. To solve this, we manipulated the domains of danger of Cape fur seal (Arctocephalus pusillus pusillus) decoys to provide evidence that a selfish reduction in a seals' domain of danger results in a proportional reduction in its predation risk from ambush shark attacks. This behaviour confers a survival advantage to individual seals within a group and explains the evolution of selfish herds in a prey species. These findings empirically elevate Hamilton's selfish herd hypothesis to more than a ‘theoretical curiosity’. PMID:19793737

  11. 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. PMID:25251559

  12. Thioredoxin System Regulation in the Central Nervous System: Experimental Models and Clinical Evidence

    PubMed Central

    Silva-Adaya, Daniela; Gonsebatt, María E.; Guevara, Jorge

    2014-01-01

    The reactive oxygen species produced continuously during oxidative metabolism are generated at very high rates in the brain. Therefore, defending against oxidative stress is an essential task within the brain. An important cellular system against oxidative stress is the thioredoxin system (TS). TS is composed of thioredoxin, thioredoxin reductase, and NADPH. This review focuses on the evidence gathered in recent investigations into the central nervous system, specifically the different brain regions in which the TS is expressed. Furthermore, we address the conditions that modulate the thioredoxin system in both, animal models and the postmortem brains of human patients associated with the most common neurodegenerative disorders, in which the thioredoxin system could play an important part. PMID:24723994

  13. Camera perspective bias in videotaped confessions: experimental evidence of its perceptual basis.

    PubMed

    Ratcliff, Jennifer J; Lassiter, G Daniel; Schmidt, Heather C; Snyder, Celeste J

    2006-12-01

    The camera perspective from which a criminal confession is videotaped influences later assessments of its voluntariness and the suspect's guilt. Previous research has suggested that this camera perspective bias is rooted in perceptual rather than conceptual processes, but these data are strictly correlational. In 3 experiments, the authors directly manipulated perceptual processing to provide stronger evidence of its mediational role. Prior to viewing a videotape of a simulated confession, participants were shown a photograph of the confessor's apparent victim. Participants in a perceptual interference condition were instructed to visualize the image of the victim in their minds while viewing the videotape; participants in a conceptual interference condition were instructed instead to rehearse an 8-digit number. Because mental imagery and actual perception draw on the same available resources, the authors anticipated that the former, but not the latter, interference task would disrupt the camera perspective bias, if indeed it were perceptually mediated. Results supported this conclusion. PMID:17154769

  14. Experimental evidence that keeping eggs dry is a mechanism for the antimicrobial effects of avian incubation

    NASA Astrophysics Data System (ADS)

    D'Alba, Liliana; Oborn, Allison; Shawkey, Matthew D.

    2010-12-01

    Avian incubation dramatically reduces the abundance and diversity of microbial assemblages on eggshells, and this effect has been hypothesized as an adaptive explanation for partial incubation, the bouts of incubation that some birds perform during the egg-laying period. However, the mechanisms for these antimicrobial effects are largely unknown. In this study, we hypothesized that microbial inhibition is partly achieved through removal of liquid water, which generally enhances microbial growth, from eggshells, and experimentally tested this hypothesis in two ways. First, we placed the first- and second-laid eggs of tree swallow ( Tachycineta bicolor) clutches in unincubated holding nests with either ambient or increased water on eggshells. Second, we added water to eggshells in naturally partially incubated nests. We compared microbial growth on shells during a 5-day experimental period and found that, as predicted, both unincubated groups had higher microbial growth than naturally partially incubated controls, and that only in the absence of incubation did wetted eggs have higher microbial growth than unwetted eggs. Thus, we have shown that water increases microbial growth on eggshells and that incubation nullifies these effects, suggesting that removal of water from egg surfaces is one proximate mechanism for the antimicrobial effects of incubation.

  15. Serial correlation in neural spike trains: Experimental evidence, stochastic modeling, and single neuron variability

    NASA Astrophysics Data System (ADS)

    Farkhooi, Farzad; Strube-Bloss, Martin F.; Nawrot, Martin P.

    2009-02-01

    The activity of spiking neurons is frequently described by renewal point process models that assume the statistical independence and identical distribution of the intervals between action potentials. However, the assumption of independent intervals must be questioned for many different types of neurons. We review experimental studies that reported the feature of a negative serial correlation of neighboring intervals, commonly observed in neurons in the sensory periphery as well as in central neurons, notably in the mammalian cortex. In our experiments we observed the same short-lived negative serial dependence of intervals in the spontaneous activity of mushroom body extrinsic neurons in the honeybee. To model serial interval correlations of arbitrary lags, we suggest a family of autoregressive point processes. Its marginal interval distribution is described by the generalized gamma model, which includes as special cases the log-normal and gamma distributions, which have been widely used to characterize regular spiking neurons. In numeric simulations we investigated how serial correlation affects the variance of the neural spike count. We show that the experimentally confirmed negative correlation reduces single-neuron variability, as quantified by the Fano factor, by up to 50%, which favors the transmission of a rate code. We argue that the feature of a negative serial correlation is likely to be common to the class of spike-frequency-adapting neurons and that it might have been largely overlooked in extracellular single-unit recordings due to spike sorting errors.

  16. Benthic Foraminifera as Proxies of Organic Flux: Experimental and Field Evidence

    NASA Astrophysics Data System (ADS)

    van der Zwaan, G. J.; Duijnstee, I. A. P.; de Nooijer, L. J.; Ernst, S. R.

    2003-04-01

    Food is one of the most important parameters in the marine realm, structuring faunal communities. Therefore, changing food flux from the mixed layer to the sea bottom is expected to be of great importance to the benthic community. In this poster we present data from 5 years of experimental work in which shallow and deeper water benthic foraminiferal associations were subjected to variable food fluxes, and even to artificial marine snow events. The experiments took place under well-controlled or well-monitored oxygen conditions. At the same time field research in the Adriatic Sea and the Levantine Basin suggests that variation in the input of nutrients greatly affects the benthic foraminiferal communities indeed, but mostly by variation of the oxygen content at the sea floor. This is confirmed by experiments. Deeper water assemblages, however, appear to be rather sensitive to changing food fluxes. In experiments with material from the Bay of Biscay high doses of organic matter result in significant response of the meiofauna: many microhabitat patterns shift to shallower depth. Some species, notably Epistominella exigua, respond after some weeks with increasing abundances; this suggests that they are good markers of eutrophic conditions. The main conclusion of experimental and field research is that short-term changes in associations are governed by the oxygen regime. Although on short time scales food does not have much effect in our experiments, it seems that on longer time scales food is of profound importance for structuring the foraminiferal community.

  17. Theoretical and experimental evidence for the post-cotunnite phase transition in zirconia at high pressure

    NASA Astrophysics Data System (ADS)

    Nishio-Hamane, Daisuke; Dekura, Haruhiko; Seto, Yusuke; Yagi, Takehiko

    2015-05-01

    A post-cotunnite phase transition in zirconia (ZrO2) at high pressure was investigated by synchrotron X-ray diffraction measurements and ab initio calculations based on density functional theory. This study successfully demonstrated a cotunnite- to Fe2P-type phase transition. Static enthalpy difference (Δ H) calculations predicted the appearance of the Fe2P phase at 124 GPa (LDA) and 143 GPa (GGA), and experimental trials demonstrated the coexistence of the Fe2P and cotunnite phases at 175 GPa after heating to 3,000 K. Both phases were quenchable to ambient conditions. The volume of the Fe2P phase was slightly less (~Δ 0.6 %) than that of the cotunnite phase over the experimental pressure range, indicating that the Fe2P phase is the higher pressure phase. The coexistence of both phases in this study may be attributed to the slow kinetics of the phase transition resulting from the close structural relationship of the two phases. An Fe2P-type structural model can be derived by applying a simple operation to the cotunnite-type structure, consisting of a 1/2 shift of several zirconium arrangements parallel to the b-axis of the cotunnite-type unit cell. It is concluded that the high-pressure cotunnite-to-Fe2P phase transition may be a common trend in many dioxides.

  18. Experimental and clinical evidence for the protective role of progesterone in motoneuron degeneration and neuroinflammation.

    PubMed

    Gonzalez Deniselle, M C; Garay, L; Meyer, M; Gargiulo-Monachelli, G; Labombarda, F; Gonzalez, S; Guennoun, R; Schumacher, M; De Nicola, Alejandro F

    2011-10-01

    Far beyond its role in reproduction, progesterone exerts neuro-protective, promyelinating, and anti-inflammatory effects in the nervous system. These effects are amplified under pathological conditions, implying that changes of the local environment sensitize nervous tissues to steroid therapy. The present survey covers our results of progesterone neuroprotection in a motoneuron neurodegeneration model and a neuroinflammation model. In the degenerating spinal cord of the Wobbler mouse, progesterone reverses the impaired expression of neurotrophins, increases enzymes of neurotransmission and metabolism, prevents oxidative damage of motoneurons and their vacuolar degeneration (paraptosis), and attenuates the development of mitochondrial abnormalities. After long-term treatment, progesterone also increases muscle strength and the survival of Wobbler mice. Subsequently, this review describes the effects of progesterone in mice with induced experimental autoimmune encephalomyelitis (EAE), a commonly used model of multiple sclerosis. In EAE mice, progesterone attenuates the clinical severity, decreases demyelination and neuronal dysfunction, increases axonal counts, reduces the formation of amyloid precursor protein profiles, and decreases the aberrant expression of growth-associated proteins. These actions of progesterone may be due to multiple mechanisms, considering that classic nuclear receptors, extranuclear receptors, and membrane receptors are all expressed in the spinal cord. Although many aspects of progesterone action in humans remain unsolved, data provided by experimental models makes getting to this objective closer than previously expected. PMID:25961276

  19. Serial correlation in neural spike trains: experimental evidence, stochastic modeling, and single neuron variability.

    PubMed

    Farkhooi, Farzad; Strube-Bloss, Martin F; Nawrot, Martin P

    2009-02-01

    The activity of spiking neurons is frequently described by renewal point process models that assume the statistical independence and identical distribution of the intervals between action potentials. However, the assumption of independent intervals must be questioned for many different types of neurons. We review experimental studies that reported the feature of a negative serial correlation of neighboring intervals, commonly observed in neurons in the sensory periphery as well as in central neurons, notably in the mammalian cortex. In our experiments we observed the same short-lived negative serial dependence of intervals in the spontaneous activity of mushroom body extrinsic neurons in the honeybee. To model serial interval correlations of arbitrary lags, we suggest a family of autoregressive point processes. Its marginal interval distribution is described by the generalized gamma model, which includes as special cases the log-normal and gamma distributions, which have been widely used to characterize regular spiking neurons. In numeric simulations we investigated how serial correlation affects the variance of the neural spike count. We show that the experimentally confirmed negative correlation reduces single-neuron variability, as quantified by the Fano factor, by up to 50%, which favors the transmission of a rate code. We argue that the feature of a negative serial correlation is likely to be common to the class of spike-frequency-adapting neurons and that it might have been largely overlooked in extracellular single-unit recordings due to spike sorting errors. PMID:19391776

  20. 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.

  1. Theoretical and experimental evidence of level repulsion states and evanescent modes in sonic crystal stubbed waveguides

    NASA Astrophysics Data System (ADS)

    Romero-García, V.; Vasseur, J. O.; Garcia-Raffi, L. M.; Hladky-Hennion, A. C.

    2012-02-01

    The complex band structures calculated using the extended plane wave expansion (EPWE) reveal the presence of evanescent modes in periodic systems, never predicted by the classical \\omega(\\vec {k}) methods, providing novel interpretations of several phenomena as well as a complete picture of the system. In this work, we theoretically and experimentally observe that in the ranges of frequencies where a deaf band is traditionally predicted, an evanescent mode with excitable symmetry appears, changing drastically the interpretation of the transmission properties. On the other hand, the simplicity of the sonic crystals in which only the longitudinal polarization can be excited is used to interpret, without loss of generality, the level repulsion between symmetric and antisymmetric bands in sonic crystals as the presence of an evanescent mode connecting both repelled bands. These evanescent modes, obtained using EPWE, explain both the attenuation produced in this range of frequencies and the transfer of symmetry from one band to the other in good agreement with both experimental results and multiple scattering predictions. Thus, the evanescent properties of the periodic system have been revealed to be necessary for the design of new acoustic and electromagnetic applications based on periodicity.

  2. Experimental evidence of population differences in reproductive investment conditional on environmental stochasticity.

    PubMed

    Gauthey, Zoé; Panserat, Stéphane; Elosegi, Arturo; Herman, Alexandre; Tentelier, Cédric; Labonne, Jacques

    2016-01-15

    Environmental stochasticity is expected to shape life histories of species, wherein organisms subjected to strong environmental variation should display adaptive response by being able to tune their reproductive investment. For riverine ecosystems, climate models forecast an increase in the frequency and intensity of extreme events such as floods and droughts. The speed and the mechanisms by which organisms may adapt their reproductive investment are therefore of primary importance to understand how species will cope with such radical environmental changes. In the present study, we sampled spawners from two different populations of wild brown trout, originating from two environments with contrasting levels of flow stochasticity. We placed them in sympatry within an experimental channel during reproductive season. In one modality, water flow was maintained constant, whereas in another modality, water flow was highly variable. Reproductive investment of all individuals was monitored using weight and energetic plasma metabolite variation throughout the reproductive season. Only the populations originating from the most variable environment showed a plastic response to experimental manipulation of water flow, the females being able to reduce their weight variation (from 19.2% to 13.1%) and metabolites variations (from 84.2% to 18.6% for triglycerides for instance) under variable flow conditions. These results imply that mechanisms to cope with environmental stochasticity can differ between populations of the same species, where some populations can be plastic whereas other cannot. PMID:26406108

  3. Experimental Evidence of melt-brake at seismic rates in sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Kuo, L.; Suppe, J.; Song, S.; Song, Y.; Yeh, E.; Dong, J.; Wang, C.; Yang, C.

    2011-12-01

    Frictional melts generated along seismic faults theoretically may act either as a lubricant or as a viscous brake. Present geological and geophysical evidence supports melt-lubrication, which is also in good agreement with extreme strength weakening in laboratory frictional experiments. On the contrary, the strengthening behavior of viscous melts at seismic rates is not well reported, especially in sedimentary rocks. Here we provide laboratory evidence of progressive increase in frictional resistance on sandstone at a slip rate of 1.3 m/s with melt generation. The produced melt/pseudotachylyte is observed with Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and is in-situ analyzed with X-ray diffraction analysis (XRD) and Transmission X-ray Microscopy (TXM) in synchrotron radiation. These analytical results show that the formation of pseudotachylyte is composed of pulverized quartz grains suspending in amorphous melts from thermally decomposed clay minerals. The observation of TXM also indicates that the shapes of quartz grains in the slip zone vary from rounded in the central area to angular on the rim. In-situ microstructures and high frictional resistance of sandstones in experiments indicate that the dominant strengthening mechanism is possibly controlled by viscous melts with suspending quartz grains. The melt rheology at high slip rates is not well understood, but the frictional behavior of melt with nano-sized quartz grains appears to be rheopetic instead of melt lubrication and/or powder lubrication. Thus, it suggests that the first-time rupture of sedimentary faults is not lubricated by melts during earthquake; in contrast melts from thermally decomposed clay minerals with suspending quartz grains produced by faulting may be an important process for the dynamic strengthening of faults.

  4. Evidence evaluation: measure Z corresponds to human utility judgments better than measure L and optimal-experimental-design models.

    PubMed

    Rusconi, Patrice; Marelli, Marco; D'Addario, Marco; Russo, Selena; Cherubini, Paolo

    2014-05-01

    Evidence evaluation is a crucial process in many human activities, spanning from medical diagnosis to impression formation. The present experiments investigated which, if any, normative model best conforms to people's intuition about the value of the obtained evidence. Psychologists, epistemologists, and philosophers of science have proposed several models to account for people's intuition about the utility of the obtained evidence with respect either to a focal hypothesis or to a constellation of hypotheses. We pitted against each other the so-called optimal-experimental-design models (i.e., Bayesian diagnosticity, log₁₀ diagnosticity, information gain, Kullback-Leibler distance, probability gain, and impact) and measures L and Z to compare their ability to describe humans' intuition about the value of the obtained evidence. Participants received words-and-numbers scenarios concerning 2 hypotheses and binary features. They were asked to evaluate the utility of "yes" and "no" answers to questions about some features possessed in different proportions (i.e., the likelihoods) by 2 types of extraterrestrial creatures (corresponding to 2 mutually exclusive and exhaustive hypotheses). Participants evaluated either how an answer was helpful or how an answer decreased/increased their beliefs with respect either to a single hypothesis or to both hypotheses. We fitted mixed-effects models and used the Akaike information criterion and the Bayesian information criterion values to compare the competing models of the value of the obtained evidence. Overall, the experiments showed that measure Z was the best fitting model of participants' judgments of the value of obtained answers. We discussed the implications for the human hypothesis-evaluation process. PMID:24446753

  5. Hydrological behaviour of microbiotic crusts on sand dunes of NW China: Experimental evidences and numerical simulations

    NASA Astrophysics Data System (ADS)

    Wang, Xin Ping; Tedeschi, Anna; Orefice, Nadia; de Mascellis, Roberto; Menenti, Massimo

    2010-05-01

    Large ecological engineering projects were established to reduce and combat the hazards of sandstorms and desertification in northern China. An experiment to evaluate the effects of dunes stabilization by vegetation was carried out at Shapotou in Ningxia Hui Autonomous Region at the southeast edge of the Tengger Desert using xerophyte shrubs (Caragana korshinskii, Hedysarum scoparium and Artemisia ordosica) planted in straw checkerboard plots in 1956, 1964, 1981, 1987, 1998, and 2002. The fixed sand surface led to the formation of biotic soil crusts. Biotic crusts formed at the soil surface in the interspaces between shrubs and contribute to stabilization of soil surfaces. Previous results on the area have showed that: i) straw checkerboards enhance the capacity of the dune system to trap dust, leading to the accumulation of soil organic matter and nutrients; ii) the longer the period of dune stabilization, the greater the soil clay content in the shallow soil profile (0-5 cm), and greater the fractal dimension of soil particle size distribution. Benefit apart, one should be aware that the formation of a crusted layer at the soil surface is generally characterized by an altered pore-size distribution, with a frequent decrease of hydraulic conductivity which can induce changes of the water regime of the whole soil profile. Accordingly, the main objective of the paper is to evaluate the equivalent (from a hydraulic point of view) geometry of the crusted layer and to verify if the specific characteristics of the crusted soil layer, although local by nature, affect the hydrological behaviour of the whole soil profile. In fact, it is expected that, due to the formation of an upper, impeding soil layer, the lower soil layers do not reach saturation. Such behaviour has important consequences on both water flow and storages in soils. The final aim will be to understand how the crust at the surface of the artificially stabilized sand dune affects the infiltration capacity

  6. Experimental evidence of frequency and fluid effects in an icelandic basalt

    NASA Astrophysics Data System (ADS)

    Adelinet, Mathilde; Fortin, Jérôme; Guéguen, Yves; Schubnel, Alexandre; Geoffroy, Laurent

    2010-05-01

    An important area of geophysical research is based on the elastic properties variations in rocks. In the laboratory, the responses of the rock elastic velocities to stress changes in saturated or dry specimens have been studied extensively in the past using ultrasonic signals in the megahertz frequency range. However when seismic wave velocities are involved, a direct extrapolation from laboratory to field scale is not straightforward. Laboratory data are indeed obtained in the ultrasonic range, whereas field data from seismological methods are obtained at much lower frequencies (Hz). The interpretation of the seismic wave velocities, measured at the field scale, in terms of fluids and/or in terms of physical properties of the rock formation is complex. From a theoretical point of view, when cracks or pores are connected, stress can induce fluid flow from one inclusion to another; this is the squirt-flow effect. In saturated samples, several authors have shown that the measured velocities at high frequencies are generally faster than those predicted by the equations of Gassmann, which correspond to the low frequency limit of Biot's theory. In this study, we investigated the frequency and fluid effects through an experimental point of view. We conducted hydrostatic experiments on an icelandic basalt, characterized by a bimodal porosity (~1% of cracks and ~7 % of equant pores; the total porosity is ~8%). The bulk moduli were measured through two experimental methods: a classical one using ultrasonic P- and S-waves velocities (frequency 106 Hz), and a new one based on oscillation tests (frequency 10-2 Hz). Measurements have been performed in the pressure range of 0- 200 MPa, both for low frequency and high frequency. In dry conditions, no significant differences are observed between high and low frequency bulk moduli. However, in saturated conditions, two effects are highlighted: a physico-chemical effect emphasized by a difference between drained and dry moduli, and

  7. Molecular dynamics prediction and experimental evidence for density of normal and metastable liquid zirconium

    NASA Astrophysics Data System (ADS)

    Wang, H. P.; Yang, S. J.; Hu, L.; Wei, B.

    2016-06-01

    The density of normal and metastable undercooled liquid zirconium was predicted by performing molecular dynamics calculation with a system consisting of 4000 atoms and measured by electrostatic levitation experiments. The results show that the density increases linearly with the descending of temperature, including a maximum undercooling of 928 K. The density is 6.00 g cm-3 at the melting temperature, which agrees well with the experimental result of 6.06 g cm-3. Furthermore, the atomic number is increased to 32,000 on the basis of 4000 atoms and there appears only 0.02% difference. Besides, the pair distribution function was applied to display the atomic structure, which indicates the liquid structure change occurs at the first neighbor distance.

  8. Does changing behavioral intentions engender behavior change? A meta-analysis of the experimental evidence.

    PubMed

    Webb, Thomas L; Sheeran, Paschal

    2006-03-01

    Numerous theories in social and health psychology assume that intentions cause behaviors. However, most tests of the intention- behavior relation involve correlational studies that preclude causal inferences. In order to determine whether changes in behavioral intention engender behavior change, participants should be assigned randomly to a treatment that significantly increases the strength of respective intentions relative to a control condition, and differences in subsequent behavior should be compared. The present research obtained 47 experimental tests of intention-behavior relations that satisfied these criteria. Meta-analysis showed that a medium-to-large change in intention (d = 0.66) leads to a small-to-medium change in behavior (d = 0.36). The review also identified several conceptual factors, methodological features, and intervention characteristics that moderate intention-behavior consistency. PMID:16536643

  9. 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.

  10. Adolescents' implicit theories predict desire for vengeance after peer conflicts: correlational and experimental evidence.

    PubMed

    Yeager, David S; Trzesniewski, Kali H; Tirri, Kirsi; Nokelainen, Petri; Dweck, Carol S

    2011-07-01

    Why do some adolescents respond to interpersonal conflicts vengefully, whereas others seek more positive solutions? Three studies investigated the role of implicit theories of personality in predicting violent or vengeful responses to peer conflicts among adolescents in Grades 9 and 10. They showed that a greater belief that traits are fixed (an entity theory) predicted a stronger desire for revenge after a variety of recalled peer conflicts (Study 1) and after a hypothetical conflict that specifically involved bullying (Study 2). Study 3 experimentally induced a belief in the potential for change (an incremental theory), which resulted in a reduced desire to seek revenge. This effect was mediated by changes in bad-person attributions about the perpetrators, feelings of shame and hatred, and the belief that vengeful ideation is an effective emotion-regulation strategy. Together, the findings illuminate the social-cognitive processes underlying reactions to conflict and suggest potential avenues for reducing violent retaliation in adolescents. PMID:21604865

  11. Evidence for distinct chronic wasting disease (CWD) strains in experimental CWD in ferrets

    PubMed Central

    Perrott, Matthew R.; Sigurdson, Christina J.; Mason, Gary L.

    2012-01-01

    Chronic wasting disease (CWD) is an evolving prion disease of cervids (deer, elk and moose) that has been recognized in North America and Korea. Infection of non-cervid reservoir or transport species in nature is not reported. However, the ferret (Mustela putorius furo) is susceptible to CWD after experimental inoculation. Here, we report that infection of ferrets with either of two ferret CWD isolates by various routes of exposure has revealed biologically distinct strain-like properties distinguished by different clinical progression and survival period. The isolates of ferret CWD were also differentiated by the distribution of the infectious prion protein (PrPCWD) in the brain and periphery, and by the proteinase K sensitivity of PrPCWD. These findings suggest that diversity in prion conformers exists in CWD-infected cervids. PMID:21918005

  12. Experimental evidence needed to demonstrate inter- and trans-generational effects of ancestral experiences in mammals

    PubMed Central

    Dias, Brian G.; Ressler, Kerry J.

    2015-01-01

    Environmental factors routinely influence an organism’s biology. The inheritance or transmission of such influences to descendant generations would be an efficient mode of information transfer across generations. The developmental stage at which a specific environment is encountered by the ancestral generation, and the number of generations over which information about that environment is registered, determines an inter- vs. trans-generational effect of ancestral influence. This commentary will outline the distinction between these influences. While seductive in principle, inter- and trans-generational inheritance in mammals is a hotly debated area of research inquiry. We present constructive criticism of such inheritance, and suggest potential experimental avenues for reconciliation. Finally, epigenetic mechanisms present an avenue for gene regulation that is dynamic. We briefly discuss how such malleability affords the potential for a reversal of any detrimental environmental influences that might have adversely impacted ancestral or descendant generations. PMID:25154497

  13. Experimental evidence for shallow, slow-moving landslides activated by a decrease in ground temperature

    NASA Astrophysics Data System (ADS)

    Shibasaki, Tatsuya; Matsuura, Sumio; Okamoto, Takashi

    2016-07-01

    In order to understand the trigger mechanism of slow-moving landslides occurring in the early cold season from late autumn to winter, we investigated the effect of temperature on the shear strength of slip surface soils. Displacement-controlled and shear stress-controlled box shear experiments were performed on undisturbed slip zone soils under residual strength conditions. Test results conducted at temperatures from 9 to 25°C showed remarkable shear strength reductions with decreasing temperature. Creep-like slow shear displacements were induced by a decrease in temperature. These temperature-dependent shear behaviors are attributed to the rheological properties of hydrous smectite that dominantly compose the soil material along the failure surface. Our experimental results imply that ground temperature conditions influence slope instability, especially for shallow landslides occurring in smectite-bearing rock areas.

  14. Experimental evidence for proteins constituting virion components and particle morphogenesis of bacteriophage ZF40.

    PubMed

    Korol, Natalia; Van den Bossche, An; Romaniuk, Liudmyla; Noben, Jean-Paul; Lavigne, Rob; Tovkach, Fedor

    2016-03-01

    Bacteriophage ZF40 is the only currently available, temperate Myoviridae phage infecting the potato pathogen Pectobacterium carotovorum subsp. carotovorum. Despite its unusual tail morphology, its major tail sheath and tube proteins remained uncharacterized after the initial genome annotation. Using ESI tandem mass-spectrometry, 24 structural proteins of the ZF40 virion were identified, with a sequence coverage ranging between 15.8% and 87.8%. The putative function of 16 proteins could be elucidated based on secondary structure analysis and conservative domain searches. The experimental annotation of 35% of the encoded gene products within the structural region of the genome represents a complete view of the virion structure, which can serve as the basis for future structural analysis as a model phage. PMID:26887841

  15. Direct experimental evidence of back-surface ion acceleration from laser-irradiated gold foils.

    PubMed

    Allen, Matthew; Patel, Pravesh K; Mackinnon, Andrew; Price, Dwight; Wilks, Scott; Morse, Edward

    2004-12-31

    Au foils were irradiated with a 100-TW, 100-fs laser at intensities greater than 10(20) W/cm2 producing proton beams with a total yield of approximately 10(11) and maximum proton energy of >9 MeV. Removing contamination from the back surface of Au foils with an Ar-ion sputter gun reduced the total yield of accelerated protons to less than 1% of the yield observed without removing contamination. Removing contamination from the front surface (laser-interaction side) of the target had no observable effect on the proton beam. We present a one-dimensional particle-in-cell simulation that models the experiment. Both experimental and simulation results are consistent with the back-surface acceleration mechanism described in the text. PMID:15697987

  16. Experimental evidence for chick discrimination without recognition in a brood parasite host

    PubMed Central

    Grim, Tomáš

    2006-01-01

    Recognition is considered a critical basis for discriminatory behaviours in animals. Theoretically, recognition and discrimination of parasitic chicks are not predicted to evolve in hosts of brood parasitic birds that evict nest-mates. Yet, an earlier study showed that host reed warblers (Acrocephalus scirpaceus) of an evicting parasite, the common cuckoo (Cuculus canorus), can avoid the costs of prolonged care for unrelated young by deserting the cuckoo chick before it fledges. Desertion was not based on specific recognition of the parasite because hosts accept any chick cross-fostered into their nests. Thus, the mechanism of this adaptive host response remains enigmatic. Here, I show experimentally that the cue triggering this ‘discrimination without recognition’ behaviour is the duration of parental care. Neither the intensity of brood care nor the presence of a single-chick in the nest could explain desertions. Hosts responded similarly to foreign chicks, whether heterospecific or experimental conspecifics. The proposed mechanism of discrimination strikingly differs from those found in other parasite–host systems because hosts do not need an internal recognition template of the parasite's appearance to effectively discriminate. Thus, host defences against parasitic chicks may be based upon mechanisms qualitatively different from those operating against parasitic eggs. I also demonstrate that this discriminatory mechanism is non-costly in terms of recognition errors. Comparative data strongly suggest that parasites cannot counter-evolve any adaptation to mitigate effects of this host defence. These findings have crucial implications for the process and end-result of host–parasite arms races and our understanding of the cognitive basis of discriminatory mechanisms in general. PMID:17164201

  17. Isostaticity and Controlled Force Transmission in the Cytoskeleton: A Model Awaiting Experimental Evidence

    PubMed Central

    Blumenfeld, Raphael

    2006-01-01

    A new model is proposed for force transmission through the cytoskeleton (CSK). A general discussion is first presented on the physical principles that underlie the modeling of this phenomenon. Some fundamental problems of conventional models—continuous and discrete—are examined. It is argued that mediation of focused forces is essential for good control over intracellular mechanical signals. The difficulties of conventional continuous models in describing such mediation are traced to a fundamental assumption rather than to their being continuous. Relevant advantages and disadvantages of continuous and discrete modeling are discussed. It is concluded that favoring discrete models is based on two misconceptions, which are clarified. The model proposed here is based on the idea that focused propagation of mechanical stimuli in frameworks over large distances (compared to the mesh size) can only occur when considerable regions of the CSK are isostatic. The concept of isostaticity is explained and a recently developed continuous isostaticity theory is briefly reviewed. The model enjoys several advantages: it leads to good control over force mediation; it explains nonuniform stresses and action at a distance; it is continuous, making it possible to model force propagation over long distances; and it enables prediction of individual force paths. To be isostatic, or nearly so, CSK networks must possess specific structural characteristics, and these are quantified. Finally, several experimental observations are interpreted using the new model and implications are discussed. It is also suggested that this approach may give insight into the dynamics of reorganization of the CSK. Many of the results are amenable to experimental measurements, providing a testing ground for the proposed picture, and generic experiments are suggested. PMID:16912215

  18. 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.

  19. The mechanics of sill inception, propagation and growth: Experimental evidence for rapid reduction in magmatic overpressure

    NASA Astrophysics Data System (ADS)

    Kavanagh, J. L.; Boutelier, D.; Cruden, A. R.

    2015-07-01

    A model of magma propagation in the crust is presented using a series of analogue experiments, where dyed water is injected at a constant flux into layers of solidified gelatine. The gelatine layers are transparent and, when intruded, deform in an almost ideal-elastic manner under the experimental conditions (low gelatine concentration: 2.5 or 3 wt%, and low temperature: 5-10 °C). The upper gelatine layer was 1.0 to 1.5 times stiffer than the lower layer, with either a 'weak' or 'strong' interface strength between the gelatine layers. The gelatine is seeded with 20- 50 μm-diameter PMMA-RhB neutrally buoyant particles that are fluoresced by a pulsed, vertical laser sheet centred on the injection point. Digital image correlation (DIC) is used to calculate incremental strain and finite strain in the deforming host material as it is intruded. This is mapped in 2D for the developing experimental volcanic plumbing system that comprises a feeder dyke and sill. Since the gelatine deforms elastically, strain measurements correlate with stress. Our results indicate that, for constant magma flux, the moment of sill inception is characterised by a significant magmatic pressure decrease of up to ∼ 60%. This is evidenced by the rapid contraction of the feeder dyke at the moment the sill forms. Sill propagation is then controlled by the fracture properties of the weak interface, with fluid from the feeder dyke extracted to help grow the sill. Pressure drops during sill inception and growth are likely to be important in volcanic systems, where destabilisation of the magmatic plumbing system could trigger an eruption.

  20. Experimental evidence of statistical ensemble behavior in bed load sediment transport

    NASA Astrophysics Data System (ADS)

    Fathel, Siobhan L.; Furbish, David Jon; Schmeeckle, Mark W.

    2015-11-01

    A high-resolution data set obtained from high-speed imaging of coarse sand particles transported as bed load allows us to confidently describe the forms and qualities of the ensemble distributions of particle velocities, accelerations, hop distances, and traveltimes. Autocorrelation functions of frame-averaged values (and the decay of these functions) support the idea that the forms of these distributions become time invariant within the 5 s imaging interval. Distributions of streamwise and cross-stream particle velocities are exponential, consistent with previous experiments and theory. Importantly, streamwise particle velocities possess a "light" tail, where the largest velocities are limited by near-bed fluid velocities. Distributions of streamwise and cross-stream particle accelerations are Laplace in form and are centered on zero, consistent with equilibrium transport conditions. The majority of particle hops, measured start to stop, involve short displacements, and streamwise hop distances possess a Weibull distribution. In contrast to previous work, the distribution of traveltimes is exponential, consistent with a fixed temporal disentrainment rate. The Weibull distribution of hop distances is consistent with a decreasing spatial disentrainment rate and is related to the exponential distribution of traveltimes. By taking into account the effects of experimental censorship associated with a finite sampling window, the relationship between streamwise hop distances and traveltimes, Lx˜Tpα, likely involves an exponent of α ˜ 2. These experimental results—an exponential distribution of traveltimes Tp and a Weibull distribution of hop distances Lx with shape parameter k < 1—are consistent with a nonlinear relationship between these quantities with α > 1.

  1. The Catchment Isoscape: Theory and Experimental Evidence for the Isotopic Age of Water in a Critical Zone Observatory (Invited)

    NASA Astrophysics Data System (ADS)

    Duffy, C.; Thomas, E.; Sullivan, P. L.; Bhatt, G.; Yu, X.

    2013-12-01

    This paper deals with the theoretical controls for the 'Age' of water in upland watershed flow systems and present comprehensive experimental evidence to support the theory using stable isotopes of and at the Susquehanna/Shale Hills Critical Zone Observatory (SSH_CZO). In this context 'age' is defined as the time since water entered the watershed as precipitation. The paper first examines the theoretical basis for direct simulation of 'age' for environmental tracers in the unsaturated zone subject to dynamic flow and transport processes with mobile and immobile flow considered. The theory demonstrates that the residence time and age of an environmental tracer can be directly modeled without knowledge of the form of the underlying residence time distribution function and without adding any new parameters. On the physical side, the theory is applied to the apparent rapid attenuation of event and seasonal isotopic ratios with depth in the soil at the SSH_CZO. Comparison of the age model to experimental data provides evidence for the role of macropore-matrix flow partitioning during the non-growing cold season and root uptake from the immobile store during the growing season via transpiration and evaporation. Flow path changes during storm events are also inferred by comparing the distribution of groundwater and streamflow isotope histories.

  2. Experimental evidence for the basal generation place of the short-latency transient-evoked otoacoustic emissions.

    PubMed

    Moleti, A; Sisto, R; Lucertini, M

    2014-05-01

    Time-frequency analysis of the transient-evoked otoacoustic emission response was performed on a population of subjects affected by sensory-neural hearing loss characterized by a sharp audiometric profile, caused by firearm noise exposure (42 ears), and on a control population of normal-hearing subjects (84 ears). Time-frequency filtering permitted a careful evaluation of the relation between the audiometric profile and the spectral shape of the long- and short-latency otoacoustic components. Both filtered spectra closely follow the shape of the audiometric profile, with a frequency shift between them. The typical frequency shift was evaluated by averaging the otoacoustic spectra and the audiograms among groups of ears with the same cutoff frequency. Assuming that the otoacoustic emission source function depends on the local effectiveness of the cochlear amplifier, this experimental evidence suggests that the short-latency response is generated at a cochlear place displaced towards the base by about 0.5-1 mm with respect to the generation place of the long-latency component. The analysis of the control group demonstrates that, below 4 kHz, the observed effect is not dependent on the data acquisition and analysis procedure. These results confirm previous theoretical estimates and independent experimental evidence based on the measured latency difference between the two components. PMID:24815267

  3. Mercury accumulation in sediment cores from three Washington state lakes: evidence for local deposition from a coal-fired power plant.

    PubMed

    Furl, Chad V; Meredith, Callie A

    2011-01-01

    Mercury accumulation rates measured in age-dated sediment cores were compared at three Washington state lakes. Offutt Lake and Lake St. Clair are located immediately downwind (18 and 28 km, respectively) of a coal-fired power plant and Lake Sammamish is located outside of the immediate area of the plant (110 km). The sites immediately downwind of the power plant were expected to receive increased mercury deposition from particulate and reactive mercury not deposited at Lake Sammamish. Mercury accumulation in cores was corrected for variable sedimentation, background, and sediment focusing to estimate the anthropogenic contribution (Hg(A,F)). Results indicated lakes immediately downwind of the power plant contained elevated Hg(A,F) levels with respect to the reference lake. Estimated fluxes to Lake Sammamish were compared to measured values from a nearby mercury wet deposition collector to gauge the efficacy of the core deconstruction techniques. Total deposition calculated through the sediment core (20.7 μg/m²/year) fell just outside of the upper estimate (18.9 μg/m²/year) of total deposition approximated from the wet deposition collector. PMID:20437040

  4. Evidence of various mechanisms of Cd sequestration in the hyperaccumulator Arabidopsis halleri, the non-accumulator Arabidopsis lyrata, and their progenies by combined synchrotron-based techniques.

    PubMed

    Isaure, Marie-Pierre; Huguet, Stéphanie; Meyer, Claire-Lise; Castillo-Michel, Hiram; Testemale, Denis; Vantelon, Delphine; Saumitou-Laprade, Pierre; Verbruggen, Nathalie; Sarret, Géraldine

    2015-06-01

    Arabidopsis halleri is a model plant for Zn and Cd hyperaccumulation. The objective of this study was to determine the relationship between the chemical forms of Cd, its distribution in leaves, and Cd accumulation and tolerance. An interspecific cross was carried out between A. halleri and the non-tolerant and non-hyperaccumulating relative A. lyrata providing progenies segregating for Cd tolerance and accumulation. Cd speciation and distribution were investigated using X-ray absorption spectroscopy and microfocused X-ray fluorescence. In A. lyrata and non-tolerant progenies, Cd was coordinated by S atoms only or with a small contribution of O groups. Interestingly, the proportion of O ligands increased in A. halleri and tolerant progenies, and they were predominant in most of them, while S ligands were still present. Therefore, the binding of Cd with O ligands was associated with Cd tolerance. In A. halleri, Cd was mainly located in the xylem, phloem, and mesophyll tissue, suggesting a reallocation process for Cd within the plant. The distribution of the metal at the cell level was further discussed. In A. lyrata, the vascular bundles were also Cd enriched, but the epidermis was richer in Cd as compared with the mesophyll. Cd was identified in trichomes of both species. This work demonstrated that both Cd speciation and localization were related to the tolerance character of the plant. PMID:25873676

  5. Experimental evidence for phase separation in hydrogen-helium mixtures at Jovian planet conditions

    NASA Astrophysics Data System (ADS)

    Collins, G. W.; Brygoo, S.; Millot, M.; Rygg, J. R.; Celliers, P. M.; Eggert, J.; Boehly, T. R.; Jeanloz, R.; Loubeyre, P.

    2015-11-01

    Whether or not H-He mixtures phase separate in Jovian planets is important to our understanding of the structure and evolution of Jupiter and Saturn. Also integral to such planet models, as well as mechanisms for H-He phase separation, are the insulating-to-conducting and the molecular-to-atomic-hydrogen transitions in the H-He mixture. Coupling static and dynamic compression techniques has allowed us to make the first thermodynamic and transport measurements of H-He mixtures at deep Jovian planet conditions. These data provide evidence that the H-He fluid demixes at the high pressures and temperatures expected to exist deep inside Saturn and Jupiter. This phase separation may result in the differentiation of heavier helium clusters, leading to helium rain in the deep interior of Saturn and perhaps even in a significant outer layer of Jupiter. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory in part under Contract W-7405-Eng-48 and in part under Contract DE-AC52-07NA27344.

  6. 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.

  7. Diffusion-perfusion relationships in skeletal muscle: models and experimental evidence from inert gas washout.

    PubMed

    Piiper, J; Meyer, M

    1984-01-01

    In order to study the dependence of blood-tissue gas exchange upon diffusion, the simultaneous washout of two inert gases of differing diffusivity was investigated in isolated-perfused dog gastrocnemius preparations. The muscles were equilibrated with CH4 and SF6 via arterial blood. The washout kinetics were determined from venous blood samples analyzed by gas chromatography. The results revealed the following features: The washout of the test gases was pronouncedly multi-exponential, and could be described by three exponential components when analyzed to 5% of the initial value. The non-exponential washout was attributed to unequal distribution of capillary blood flow to tissue volume. The mean ratio of washout rate constants CH4/SF6 was within 1.10-1.25 and was even smaller than the ratio expected for pure perfusion limitation (1.46). Therefore, no evidence for effective tissue-blood diffusion limitation was obtained. The observed washout rate constant ratio could be explained by a model with veno-arterial back diffusion which more strongly retards washout kinetics of the better diffusible gas (CH4) as compared to the less diffusible gas (SF6). PMID:6731103

  8. Can people really "laugh at themselves?"--experimental and correlational evidence.

    PubMed

    Beermann, Ursula; Ruch, Willibald

    2011-06-01

    Laughing at oneself is considered a core component of the sense of humor in the theories of several authors. In McGhee's (1996) eight-step-training program of the sense of humor, laughing at oneself constitutes one of the most difficult levels. However, until now, only little empirical evidence on laughing at oneself exists. Using a multimethod approach, in the current study, 70 psychology students and a total of 126 peers filled in the Sense of Humor Scale (SHS, McGhee, 1996), containing as a subscale "Laughing at oneself". In addition, the participants answered the Trait and State forms of the State-Trait-Cheerfulness-Inventory (STCI, Ruch, Köhler, & van Thriel, 1996; Ruch, Köhler, & van Thriel, 1997). They then were confronted with six distorted images of themselves. Facial responses of the participants were videotaped and analyzed using the Facial Action Coding System (FACS, Ekman, Friesen, & Hager, 2002). Four indicators of exhilaration were examined: (a) experienced funniness, (b) AU12 smiles, (c) Duchenne displays, and (d) laughter. Furthermore, fake and masking smiles were studied. Results demonstrated that self- and peer reports of "laughing at oneself" converged moderately. All four indicators of exhilaration were shown, but funniness and laughter seemed to be the most strongly related indicators. Trait cheerfulness and (low) seriousness, and a cheerful mood state formed further characteristics of persons who laugh at themselves. PMID:21668102

  9. Experimental evidence for an intraspecific Janzen-Connell effect mediated by soil biota.

    PubMed

    Liu, Xubing; Etienne, Rampal S; Liang, Minxia; Wang, Yongfan; Yu, Shixiao

    2015-03-01

    The negative effect of soil pathogens on seedling survival varies considerably among conspecific individuals, but the underlying mechanisms are largely unknown. For variation between heterospecifics, a common explanation is the Janzen-Connell effect: negative density dependence in survival due to specialized pathogens aggregating on common hosts. We test whether an intraspecific Janzen-Connell effect exists, i.e., whether the survival chances of one population's seedlings surrounded by a different conspecific population increase with genetic difference, spatial distance, and trait dissimilarity between them. In a shade-house experiment, we grew seedlings of five populations of each of two subtropical tree species (Castanopsis fissa and Canarium album) for which we measured genetic distance using intersimple sequence repeat (ISSR) analysis and eight common traits/characters, and we treated them with soil material or soil biota filtrate collected from different populations. We found that the relative survival rate increased with increasing dissimilarity measured by spatial distance, genetic distance, and trait differences between the seedling and the population around which the soil was collected. This effect disappeared after soil sterilization. Our results provide evidence that genetic variation, trait similarity, and spatial distance can explain intraspecific variation in plant-soil biotic interactions and suggest that limiting similarity also occurs at the intraspecific level. PMID:26236863

  10. Solvation Phenomena in Dilute Solutions: Formal, Experimental Evidence, and Modeling Implications

    SciTech Connect

    Chialvo, Ariel A

    2013-01-01

    We review the fundamentals underlying a general molecular-based formalism for the microscopic interpretation of the solvation phenomena involving sparingly soluble solutes in compressible media, an approach that hinges around the unambiguous splitting of the species correlation function integrals into short-(finite) and long-ranged (diverging) contributions at infinite dilution, where this condition is taken as the reference system for the derivation of composition expansions. Then, we invoke the formalism (a) to illustrate the well-behaved nature of the solvation contributions to the mechanical partial molecular properties of solutes at infinite dilution, (b) to guide the development of, and provide molecular-based support to, the macroscopic modeling of high-temperature dilute aqueous-electrolyte solutions, (c) to study solvation effects on the kinetic rate constants of reactions in near-critical solvents in an attempt to understand from a microscopic perspective the macroscopic evidence regarding the thermodynamic pressure effects, and (d) to interpret the microscopic mechanism behind synergistic solvation effects involving either co-solutes or co-solvents, and provide a molecular argument on the unsuitability of the van der Waals one-fluid (vdW-1f) mixing rules for the 2 description of weakly attractive solutes in compressible solvents. Finally, we develop thermodynamically consistent perturbation expansions, around the infinite dilution reference, for the species residual properties in binary and ternary mixtures, and discuss the theoretical and modeling implications behind ad hoc first-order truncated expansions.

  11. Experimental evidence for the functional relevance of anion-π interactions

    NASA Astrophysics Data System (ADS)

    Dawson, Ryan E.; Hennig, Andreas; Weimann, Dominik P.; Emery, Daniel; Ravikumar, Velayutham; Montenegro, Javier; Takeuchi, Toshihide; Gabutti, Sandro; Mayor, Marcel; Mareda, Jiri; Schalley, Christoph A.; Matile, Stefan

    2010-07-01

    Attractive in theory and confirmed to exist, anion-π interactions have never really been seen at work. To catch them in action, we prepared a collection of monomeric, cyclic and rod-shaped naphthalenediimide transporters. Their ability to exert anion-π interactions was demonstrated by electrospray tandem mass spectrometry in combination with theoretical calculations. To relate this structural evidence to transport activity in bilayer membranes, affinity and selectivity sequences were recorded. π-acidification and active-site decrowding increased binding, transport and chloride > bromide > iodide selectivity, and supramolecular organization inverted acetate > nitrate to nitrate > acetate selectivity. We conclude that anion-π interactions on monomeric surfaces are ideal for chloride recognition, whereas their supramolecular enhancement by π,π-interactions appears perfect to target nitrate. Chloride transporters are relevant to treat channelopathies, and nitrate sensors to monitor cellular signaling and cardiovascular diseases. A big impact on organocatalysis can be expected from the stabilization of anionic transition states on chiral π-acidic surfaces.

  12. Experimental Evidence of an Eco-evolutionary Feedback during Adaptive Divergence.

    PubMed

    Matthews, Blake; Aebischer, Thierry; Sullam, Karen E; Lundsgaard-Hansen, Bänz; Seehausen, Ole

    2016-02-22

    Differences in how organisms modify their environment can evolve rapidly and might influence adaptive population divergence. In a common garden experiment in aquatic mesocosms, we found that adult stickleback from a recently diverged pair of lake and stream populations had contrasting effects on ecosystem metrics. These modifications were caused by both genetic and plastic differences between populations and were sometimes comparable in magnitude to those caused by the presence/absence of stickleback. Lake and stream fish differentially affected the biomass of zooplankton and phytoplankton, the concentration of phosphorus, and the abundance of several prey (e.g., copepods) and non-prey (e.g., cyanobacteria) species. The adult-mediated effects on mesocosm ecosystems influenced the survival and growth of a subsequent generation of juvenile stickleback reared in the same mesocosms. The prior presence of adults decreased the overall growth rate of juveniles, and the prior presence of stream adults lowered overall juvenile survival. Among the survivors, lake juveniles grew faster than co-occurring stream juveniles, except in mesocosm ecosystems previously modified by adult lake fish that were reared on plankton. Overall, our results provide evidence for reciprocal interactions between ecosystem dynamics and evolutionary change (i.e., eco-evolutionary feedbacks) in the early stages of adaptive population divergence. PMID:26804555

  13. 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. PMID:27185735

  14. Phylogenetic and experimental evidence for host-specialized cryptic species in a biotrophic oomycete.

    PubMed

    Rouxel, Mélanie; Mestre, Pere; Comont, Gwenaelle; Lehman, Brian L; Schilder, Annemiek; Delmotte, François

    2013-01-01

    Assortative mating resulting from host plant specialization has been proposed to facilitate rapid ecological divergence in biotrophic plant pathogens. Downy mildews, a major group of biotrophic oomycetes, are prime candidates for testing speciation by host plant specialization. Here, we combined a phylogenetic and morphological approach with cross-pathogenicity tests to investigate host plant specialization and host range expansion in grapevine downy mildew. This destructive disease is caused by Plasmopara viticola, an oomycete endemic to North America on wild species and cultivated grapevines. Multiple genealogies and sporangia morphology provide evidence that P. viticola is a complex of four cryptic species, each associated with different host plants. Cross-inoculation experiments showed complete host plant specialization on Parthenocissus quinquefolia and on Vitis riparia, whereas cryptic species found on V. aestivalis, V. labrusca and V. vinifera were revealed to be less specific. We reconstructed the recent host range expansion of P. viticola from wild to cultivated grapevines, and showed that it was accompanied by an increase in aggressiveness of the pathogen. This case study on grapevine downy mildew illustrates how biotrophic plant pathogens can diversify by host plant specialization and emerge in agrosystems by shifting to cultivated hosts. These results might have important implications for viticulture, including breeding for resistance and disease management. PMID:23153246

  15. Experimental evidence of pharmacological management of anchorage in Orthodontics: A systematic review

    PubMed Central

    Fernández-González, Felipe José; Cañigral, Aránzazu; Balbontín-Ayala, Felipe; Gonzalo-Orden, José Manuel; de Carlos, Felix; Cobo, Teresa; Fernández-Vázquez, Jose Pedro; Sánchez-Lasheras, Fernando; Vega, José Antonio

    2015-01-01

    Introduction: Orthodontic anchorage is one of the most challenging aspects of Orthodontics. Preventing undesired movement of teeth could result in safer and less complicated orthodontic treatment. Recently, several reviews have been published about the effects of different molecules on bone physiology and the clinical side effects in Orthodontics. However, the effects of local application of these substances on the rate of orthodontic tooth movement have not been assessed. Objectives: The aim of this research was to analyze the scientific evidence published in the literature about the effects of different molecules on orthodontic anchorage. Methods: The literature was systematically reviewed using PubMed/Medline, Scopus and Cochrane databases from 2000 up to July 31st, 2014. Articles were independently selected by two different researchers based on previously established inclusion and exclusion criteria, with a concordance Kappa index of 0.86. The methodological quality of the reviewed papers was performed. Results: Search strategy identified 270 articles. Twenty-five of them were selected after application of inclusion/exclusion criteria, and only 11 qualified for final analysis. Molecules involved in orthodontic anchorage were divided into three main groups: osteoprotegerin (OPG), bisphosphonates (BPs) and other molecules (OMs). Conclusions: Different drugs are able to alter the bone remodeling cycle, influencing osteoclast function and, therefore, tooth movement. Thus, they could be used in order to provide maximal anchorage while preventing undesired movements. OPG was found the most effective molecule in blocking the action of osteoclasts, thereby reducing undesired movements. PMID:26560822

  16. 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

    Quartz-carbonate veins are common in a variety of moderate temperature hydrothermal systems and ore deposits. Associated fluid inclusions have a wide range of compositions, including liquid carbon dioxide fillings. Examination of chemical and physical conditions which result precipitation of quartz and carbonate in veins raises several key questions about multiphase fluid processes and reaction rates. We have been experimentally investigating physical-chemical reaction processes of mixed brine-carbon dioxide fluids for the shallow crust. Synthetic arkose (microcline + oligoclase + quartz + biotite) plus argillaceous shale were reacted with 5.5 molal NaCl brine. The system was held at 200 C and 200 bars for 32 days to approach steady state, then injected with carbon dioxide and allowed to react for an additional 45 days. In a parallel experiment, the system was allowed to react for 77 days without injection of carbon dioxide. Trace ions initially absent from NaCl brine appeared in solution at mM (K, Ca, and silica) to uM (Mg, Al, Fe and Mn) quantities, reflecting reaction of brine with rock. Without carbon dioxide injection, the silica concentration (2.4 mM) was stable below calculated quartz solubility (3.9 mM). Injection of carbon dioxide resulted in decreased pH and increased silica concentration to a level near calculated chalcedony solubility (5.4 mM). Dissolution of silicate minerals is apparently coupled to the acidity, and concomitant inhibition of the precipitation of quartz (and other silicates). A significant increase in concentration of trace metals is consistent with in-situ pH decrease and increased carbon dioxide dissolved in brine. Multi-phase fluid reaction relationships between supercritical carbon dioxide and brine-rock systems allow formation of carbonate vein precipitates in substantial quantities. Brine and continued rock reactions provide a substantial reservoir for Ca, Mg and Fe components. A separate carbon dioxide liquid allows

  17. Experimental evidence for a cost of resistance to the fungal pathogen, Batrachochytrium dendrobatidis, for the palmate newt, Lissotriton helveticus

    PubMed Central

    2013-01-01

    Background Batrachochytrium dendrobatidis (Bd), the causative agent of chytridiomycosis, is decimating amphibians worldwide. Unsurprisingly, the majority of studies have therefore concentrated on documenting morbidity and mortality of susceptible species and projecting population consequences as a consequence of this emerging infectious disease. Currently, there is a paucity of studies investigating the sub-lethal costs of Bd in apparently asymptomatic species, particularly in controlled experimental conditions. Here we report the consequences of a single dose of B. dendrobatidis zoospores on captive adult palmate newts (Lissotriton helveticus) for morphological and behavioural traits that associate with reproductive success. Results A single exposure to ~2000 zoospores induced a subclinical Bd infection. One week after inoculation 84% of newts tested positive for Bd, and of those, 98% had apparently lost the infection by the day 30. However, exposed newts suffered significant mass loss compared with control newts, and those experimental newts removing higher levels of Bd lost most mass. We found no evidence to suggest that three secondary sexual characteristics (areas of dorsal crest and rear foot webbing, and length of tail filament) were reduced between experimental versus control newts; in fact, rear foot webbing was 26% more expansive at the end of the experiment in exposed newts. Finally, compared with unexposed controls, exposure to Bd was associated with a 50% earlier initiation of the non-reproductive terrestrial phase. Conclusions Our results suggest that Bd has measureable, but sub-lethal effects, on adult palmate newts, at least under the laboratory conditions presented. We conclude that the effects reported are most likely to be mediated through the initiation of costly immune responses and/or tissue repair mechanisms. Although we found no evidence of hastened secondary sexual trait regression, through reducing individual body condition and potentially

  18. A Spotlight on Liquefaction: Evidence from Clinical Settings and Experimental Models in Tuberculosis

    PubMed Central

    Cardona, Pere-Joan

    2011-01-01

    Liquefaction is one of the most intriguing aspects of human tuberculosis. It is a major cause of the transition from the infection to active disease (tuberculosis, TB) as well as the transmission of M. tuberculosis to other persons. This paper reviews the natural history of liquefaction in humans from a pathological and radiological point of view and discusses how the experimental models available can be used to address the topic of liquefaction and cavity formation. Different concepts that have been related to liquefaction, from the influence of immune response to mechanical factors, are reviewed. Synchronic necrosis or apoptosis of infected macrophages in a close area, together with an ineffective fibrosis, appears to be clue in this process, in which macrophages, the immune response, and bacillary load interact usually in a particular scenario: the upper lobes of the lung. The summary would be that even if being a stochastic effect, liquefaction would result if the organization of the intragranulomatous necrosis (by means of fibrosis) would be disturbed. PMID:21437230

  19. Testing Basic Laws of Gravitation - Are Our Postulates on Dynamics and Gravitation Supported by Experimental Evidence?

    NASA Astrophysics Data System (ADS)

    Lämmerzahl, Claus

    Gravity is the most fundamental interaction; it not only describes a particular interaction between matter, but also encompasses issues such as the notion of space and time, the role of the observer, and the relativistic measurement process. Gravity is geometry and, in consequence, allows the existence of horizons and black holes, nontrivial topologies, a cosmological big bang, time-travel, warp drive, and other phenomena unknown in nonrelativistic physics. Here we present the experimental basis of General Relativity, addressing its foundations encoded in the Einstein Equivalence Principle and its predictions in the weak and strong gravity regimes. We discuss several approaches in the search to reveal an influence of the much sought-after quantum theory of gravity. We emphasize assumptions underlying the dynamics - for example, Newton's axioms and conservation laws - and the current extent to which they are supported by experiment. We discuss conditions under which gravity can be transformed away locally, and examine higher order time derivatives in the equations of motion.

  20. Experimental evidence regarding the pressure dependence of fission track annealing in apatite

    NASA Astrophysics Data System (ADS)

    Schmidt, J. S.; Lelarge, M. L. M. V.; Conceicao, R. V.; Balzaretti, N. M.

    2014-03-01

    The main purposes of fission track thermochronology are unravelling the thermal histories of sedimentary basins, determining uplift and denudation rates, identifying the structural evolution of orogenic belts, determining sedimentary provenance, and dating volcanic rocks. The effect of temperature on fission tracks is well known and is used to determine the thermal history; however, the effect of pressure on the stability of tracks is still under debate. The present work aims to understand the role of pressure on the annealing kinetics of apatite fission tracks. The samples of Durango apatite used in our experiments were chosen for their international recognition as a calibration standard for geological dating. Neutron irradiation of the samples, after total annealing of their spontaneous tracks, produced induced tracks with homogeneous densities and lengths. The effect of pressure associated with temperature on fission track annealing was verified by experimental procedures using a hydraulic press of 1000 t with a toroidal chamber profile. The experiments consisted of a combination of applying 2 and 4 GPa with 20,150,190,235, and 290 °C for 1 and 10 h. The annealing rate was analysed by measuring the lengths of the fission tracks after each experiment using optical microscopy. The results demonstrate that the annealing of apatite fission tracks has a pressure dependence for samples subjected to 2 and 4 GPa. However, when extrapolated to pressures of ⩽150 MPa, compatible with the normal geological context in which apatite fission track methodology is broadly used, this dependence becomes insignificant compared to the temperature effect.

  1. First experimental evidence for female mate choice in a nocturnal primate.

    PubMed

    Craul, Mathias; Zimmermann, Elke; Radespiel, Ute

    2004-10-01

    Female mate choice can be hypothesised in most nocturnal primates, since females show a higher investment in their offspring than males. The aim of this experimental study was to investigate if female grey mouse lemurs perform mate choice and whether age, relatedness (to the male), or male advertisement call activity systematically influence their decisions. A two-way mate choice design was developed in which females could choose between two males. Mate choice was deduced from the time spent in proximity to the males and from mating behaviour. During oestrus 12 of 17 females participated actively in the experiment and all of them showed either a significant spatial (n = 11) or behavioural (n = 1) preference for one male. In four cases copulations were observed. The influence of age on female mate choice was not statistically significant. In the cases with copulations, however, females mostly preferred the older male. This might indicate a preference for older age as an indicator of experience, fitness, and/or status. The influence of relatedness on female mate choice could not be definitely clarified. However, results imply a mechanism of kin recognition on the basis of familiarity. In the majority of choices, females preferred the male with higher trill call activity. Since trill call activity correlates with the relative dominance status of males, these results suggest an importance of the male dominance status for female mate choice in grey mouse lemurs. Altogether our findings indicate that females use a complex of different cues to choose their mates. PMID:15241637

  2. Evidence of apoptotic cell death after experimental traumatic brain injury in the rat.

    PubMed Central

    Rink, A.; Fung, K. M.; Trojanowski, J. Q.; Lee, V. M.; Neugebauer, E.; McIntosh, T. K.

    1995-01-01

    Apoptosis plays an important role in many developmental and pathological processes of the central nervous system. However, the role of apoptosis in traumatic brain injury has not been determined. Using the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick end labeling (TUNEL) method, we detected many cells with extensive DNA fragmentation in different regions of the brains of rats subjected to experimental traumatic brain injury. Two types of TUNEL-positive cells were demonstrated by light and electron microscopy, including type I cells that displayed morphological features of necrotic cell death and type II cells that displayed morphological features of classic apoptotic cell death. TUNEL-positive cells were detectable for up to 72 hours after the initial injury. Gel electrophoresis of DNA extracted from affected areas of the injured brain containing both type I and II cells revealed only internucleosomal fragmentation at 185-bp intervals, a feature originally described in apoptotic cell death. These data suggest that apoptosis, in addition to necrotic cell death, occurs after traumatic brain injury, and that internucleosomal fragmentation of DNA may be associated with certain types of necrotic cell death. Images Figure 1 Figure 2 Figure 4 PMID:7495282

  3. The neuronal norepinephrine transporter in experimental heart failure: evidence for a posttranscriptional downregulation.

    PubMed

    Backs, J; Haunstetter, A; Gerber, S H; Metz, J; Borst, M M; Strasser, R H; Kübler, W; Haass, M

    2001-03-01

    An impairment of norepinephrine (NE) re-uptake by the neuronal NE transporter (NET) has been shown to contribute to the increased cardiac net-release of NE in congestive heart failure (CHF). The present study investigated which mechanisms are involved in the impairment of NET. Rats with supracoronary aortic banding characterized by myocardial hypertrophy, elevated left ventricular end diastolic pressures and severe pulmonary congestion were used as an experimental model for CHF. Compared to sham-operated controls, aortic-banded rats had enhanced plasma NE concentrations and decreased cardiac NE stores. In isolated perfused hearts of aortic-banded rats, functional impairment of NET was indicated by a 37% reduction in [(3)H]-NE-uptake. In addition, pharmacological blockade of NET with desipramine led to a markedly attenuated increase in the overflow of endogenous NE from hearts of aortic-banded rats. Determination of cardiac NET protein and of NET mRNA in the left stellate ganglion by [(3)H]-desipramine binding and competitive RT-PCR, respectively, revealed a 41% reduction of binding sites but no difference in gene expression. The density of sympathetic nerve fibers within the heart was unchanged, as shown by glyoxylic acid-induced histofluorescence. In conclusion, as impairment of intracardiac NE re-uptake by a reduction of NET binding sites is neither mediated by a decreased NET gene expression nor by a loss of noradrenergic nerve terminals, a posttranscriptional downregulation of NET per neuron is suggested in CHF. PMID:11181015

  4. Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils.

    PubMed

    Colleary, Caitlin; Dolocan, Andrei; Gardner, James; Singh, Suresh; Wuttke, Michael; Rabenstein, Renate; Habersetzer, Jörg; Schaal, Stephan; Feseha, Mulugeta; Clemens, Matthew; Jacobs, Bonnie F; Currano, Ellen D; Jacobs, Louis L; Sylvestersen, Rene Lyng; Gabbott, Sarah E; Vinther, Jakob

    2015-10-13

    In living organisms, color patterns, behavior, and ecology are closely linked. Thus, detection of fossil pigments may permit inferences about important aspects of ancient animal ecology and evolution. Melanin-bearing melanosomes were suggested to preserve as organic residues in exceptionally preserved fossils, retaining distinct morphology that is associated with aspects of original color patterns. Nevertheless, these oblong and spherical structures have also been identified as fossilized bacteria. To date, chemical studies have not directly considered the effects of diagenesis on melanin preservation, and how this may influence its identification. Here we use time-of-flight secondary ion mass spectrometry to identify and chemically characterize melanin in a diverse sample of previously unstudied extant and fossil taxa, including fossils with notably different diagenetic histories and geologic ages. We document signatures consistent with melanin preservation in fossils ranging from feathers, to mammals, to amphibians. Using principal component analyses, we characterize putative mixtures of eumelanin and phaeomelanin in both fossil and extant samples. Surprisingly, both extant and fossil amphibians generally exhibit melanosomes with a mixed eumelanin/phaeomelanin composition rather than pure eumelanin, as assumed previously. We argue that experimental maturation of modern melanin samples replicates diagenetic chemical alteration of melanin observed in fossils. This refutes the hypothesis that such fossil microbodies could be bacteria, and demonstrates that melanin is widely responsible for the organic soft tissue outlines in vertebrates found at exceptional fossil localities, thus allowing for the reconstruction of certain aspects of original pigment patterns. PMID:26417094

  5. Yes, it turns: experimental evidence of pearl rotation during its formation

    PubMed Central

    Gueguen, Yannick; Czorlich, Yann; Mastail, Max; Le Tohic, Bruno; Defay, Didier; Lyonnard, Pierre; Marigliano, Damien; Gauthier, Jean-Pierre; Bari, Hubert; Lo, Cedrik; Chabrier, Sébastien; Le Moullac, Gilles

    2015-01-01

    Cultured pearls are human creations formed by inserting a nucleus and a small piece of mantle tissue into a living shelled mollusc, usually a pearl oyster. Although many pearl observations intuitively suggest a possible rotation of the nucleated pearl inside the oyster, no experimental demonstration of such a movement has ever been done. This can be explained by the difficulty of observation of such a phenomenon in the tissues of a living animal. To investigate this question of pearl rotation, a magnetometer system was specifically engineered to register magnetic field variations with magnetic sensors from movements of a magnetic nucleus inserted in the pearl oyster. We demonstrated that a continuous movement of the nucleus inside the oyster starts after a minimum of 40 days post-grafting and continues until the pearl harvest. We measured a mean angular speed of 1.27° min−1 calculated for four different oysters. Rotation variability was observed among oysters and may be correlated to pearl shape and defects. Nature's ability to generate so amazingly complex structures like a pearl has delivered one of its secrets. PMID:26587271

  6. Evidence of gating in hundred nanometer diameter pores: an experimental and theoretical study

    SciTech Connect

    Letant, S E; Schaldach, C M; Johnson, M R; Sawvel, A; Bourcier, W L; Wilson, W D

    2006-01-11

    We report on the observation of an unexpected gating mechanism at the 100 nm scale on track-etched polycarbonate membranes. Transport measurements of methyl viologen performed by absorption spectroscopy under various pH conditions demonstrated that perfect gating was achieved for 100 nm diameter pores at pH 2, while the positively charged molecular ions moved through the membrane according to diffusion laws at pH 5. An oppositely charged molecular ion, naphthalene disulfonate, in the same membrane, showed the opposite trend: diffusion of the negative ion at pH 2 and perfect gating at pH 5. The influence of parameters such as ionic strength and membrane surface coating were also investigated. A theoretical study of the system shows that at this larger length scale the magnitude of the electric field in the vicinity of the pores is too small to account for the experimental observations, rather, it is the surface trapping of the mobile ion (Cl{sup -} or Na{sup +}) which gives rise to the gating phenomena. This surprising effect might have potential applications for high-throughput separation of large molecules and bio-organisms.

  7. Quantum Criticality in an Ising Chain: Experimental Evidence for Emergent E8 Symmetry

    NASA Astrophysics Data System (ADS)

    Coldea, R.; Tennant, D. A.; Wheeler, E. M.; Wawrzynska, E.; Prabhakaran, D.; Telling, M.; Habicht, K.; Smeibidl, P.; Kiefer, K.

    2010-01-01

    Quantum phase transitions take place between distinct phases of matter at zero temperature. Near the transition point, exotic quantum symmetries can emerge that govern the excitation spectrum of the system. A symmetry described by the E8 Lie group with a spectrum of eight particles was long predicted to appear near the critical point of an Ising chain. We realize this system experimentally by using strong transverse magnetic fields to tune the quasi-one-dimensional Ising ferromagnet CoNb2O6 (cobalt niobate) through its critical point. Spin excitations are observed to change character from pairs of kinks in the ordered phase to spin-flips in the paramagnetic phase. Just below the critical field, the spin dynamics shows a fine structure with two sharp modes at low energies, in a ratio that approaches the golden mean predicted for the first two meson particles of the E8 spectrum. Our results demonstrate the power of symmetry to describe complex quantum behaviors.

  8. Quantum criticality in an Ising chain: experimental evidence for emergent E8 symmetry.

    PubMed

    Coldea, R; Tennant, D A; Wheeler, E M; Wawrzynska, E; Prabhakaran, D; Telling, M; Habicht, K; Smeibidl, P; Kiefer, K

    2010-01-01

    Quantum phase transitions take place between distinct phases of matter at zero temperature. Near the transition point, exotic quantum symmetries can emerge that govern the excitation spectrum of the system. A symmetry described by the E8 Lie group with a spectrum of eight particles was long predicted to appear near the critical point of an Ising chain. We realize this system experimentally by using strong transverse magnetic fields to tune the quasi-one-dimensional Ising ferromagnet CoNb2O6 (cobalt niobate) through its critical point. Spin excitations are observed to change character from pairs of kinks in the ordered phase to spin-flips in the paramagnetic phase. Just below the critical field, the spin dynamics shows a fine structure with two sharp modes at low energies, in a ratio that approaches the golden mean predicted for the first two meson particles of the E8 spectrum. Our results demonstrate the power of symmetry to describe complex quantum behaviors. PMID:20056884

  9. Impact of Bisphenol A on the Cardiovascular System — Epidemiological and Experimental Evidence and Molecular Mechanisms

    PubMed Central

    Gao, Xiaoqian; Wang, Hong-Sheng

    2014-01-01

    Bisphenol A (BPA) is a ubiquitous plasticizing agent used in the manufacturing of polycarbonate plastics and epoxy resins. There is well-documented and broad human exposure to BPA. The potential risk that BPA poses to the human health has attracted much attention from regulatory agencies and the general public, and has been extensively studied. An emerging and rapidly growing area in the study of BPA’s toxicity is its impact on the cardiovascular (CV) system. Recent epidemiological studies have shown that higher urinary BPA concentration in humans is associated with various types of CV diseases, including angina, hypertension, heart attack and coronary and peripheral arterial disease. Experimental studies have demonstrated that acute BPA exposure promotes the development of arrhythmias in female rodent hearts. Chronic exposure to BPA has been shown to result in cardiac remodeling, atherosclerosis, and altered blood pressure in rodents. The underlying mechanisms may involve alteration of cardiac Ca2+ handling, ion channel inhibition/activation, oxidative stress, and genome/transcriptome modifications. In this review, we discuss these recent findings that point to the potential CV toxicity of BPA, and highlight the knowledge gaps in this growing research area. PMID:25153468

  10. Experimental evidence of impacts of an invasive parakeet on foraging behavior of native birds.

    PubMed

    Peck, Hannah L; Pringle, Henrietta E; Marshall, Harry H; Owens, Ian P F; Lord, Alexa M

    2014-05-01

    Resource competition is one potential behavioral mechanism by which invasive species can impact native species, but detecting this competition can be difficult due to the interactions that variable environmental conditions can have on species behavior. This is particularly the case in urban habitats where the disturbed environment can alter natural behavior from that in undisturbed habitats. The rose-ringed parakeet (Psittacula krameri), is an increasingly common invasive species, predominantly associated with large urban centers. Using an experimental approach, we tested the behavioral responses of native garden birds in response to the presence of a rose-ringed parakeet versus the presence of a similarly sized and dominant native bird, the great spotted woodpecker (Dendrocopos major). Parakeet presence significantly reduced feeding rates and increased vigilance among native birds compared with our control treatments. Of visits made by native birds in the presence of a parakeet, feeding was more likely to occur in sites within the parakeet range compared with sites outside, suggesting some habituation of native birds has occurred following prior exposure to parakeets but overall foraging behavior is still disrupted. The results of our study suggest that nonnative species can have complex and subtle impacts on native fauna and show that a nonnative competitor can impact native species simply through their presence near resources. PMID:24822022

  11. Experimental evidence of impacts of an invasive parakeet on foraging behavior of native birds

    PubMed Central

    2014-01-01

    Resource competition is one potential behavioral mechanism by which invasive species can impact native species, but detecting this competition can be difficult due to the interactions that variable environmental conditions can have on species behavior. This is particularly the case in urban habitats where the disturbed environment can alter natural behavior from that in undisturbed habitats. The rose-ringed parakeet (Psittacula krameri), is an increasingly common invasive species, predominantly associated with large urban centers. Using an experimental approach, we tested the behavioral responses of native garden birds in response to the presence of a rose-ringed parakeet versus the presence of a similarly sized and dominant native bird, the great spotted woodpecker (Dendrocopos major). Parakeet presence significantly reduced feeding rates and increased vigilance among native birds compared with our control treatments. Of visits made by native birds in the presence of a parakeet, feeding was more likely to occur in sites within the parakeet range compared with sites outside, suggesting some habituation of native birds has occurred following prior exposure to parakeets but overall foraging behavior is still disrupted. The results of our study suggest that nonnative species can have complex and subtle impacts on native fauna and show that a nonnative competitor can impact native species simply through their presence near resources. PMID:24822022

  12. Optical manipulation of complex molecular systems by high density green photons: experimental and theoretical evidence

    NASA Astrophysics Data System (ADS)

    Comorosan, Sorin; Polosan, Silviu; Popescu, Irinel; Stamatin, Ioan; Ionescu, Elena; Avramescu, Sorin; Cristian Cune, Liviu; Apostol, Marian

    2013-05-01

    The recent revolution in modern optical techniques revealed that light interaction with matter generates a force, known as optical force, which produces material properties known in physics as optical matter. The basic technique of the domain uses forces exerted by a strongly focused beam of light to trap small objects and subsequently to manipulate their local structures. The purpose of this paper is to develop an alternative approach, using irradiations with high-density-green-photons, which induce electric dipoles by polarization effects. The materials used for the experiments were long carbon chains which represent the framework of biological macromolecules. The physical techniques used to reveal the locally induced molecular arrangements were: dynamic viscosity, zeta potential, chemiluminescence, liquid chromatography; mass spectrometry, and Raman and infrared spectroscopy. The principal result of our experiments was the detection of different molecular arrangements within the mixture of alkane chains, generated by our optical manipulations. This induced "optical matter" displayed two material properties: antioxidant effects and large molecular aggregation effects. In order to bring the experimental results in relation with theory, we developed a physical model and the interacting force between polarizable bodies was computed. By numerical calculations stable structures for N = 6 and N = 8 particles were obtained.

  13. Overconfidence in wargames: experimental evidence on expectations, aggression, gender and testosterone

    PubMed Central

    Johnson, Dominic D.P; McDermott, Rose; Barrett, Emily S; Cowden, Jonathan; Wrangham, Richard; McIntyre, Matthew H; Peter Rosen, Stephen

    2006-01-01

    Summary Overconfidence has long been noted by historians and political scientists as a major cause of war. However, the origins of such overconfidence, and sources of variation, remain poorly understood. Mounting empirical studies now show that mentally healthy people tend to exhibit psychological biases that encourage optimism, collectively known as ‘positive illusions’. Positive illusions are thought to have been adaptive in our evolutionary past because they served to cope with adversity, harden resolve, or bluff opponents. Today, however, positive illusions may contribute to costly conflicts and wars. Testosterone has been proposed as a proximate mediator of positive illusions, given its role in promoting dominance and challenge behaviour, particularly in men. To date, no studies have attempted to link overconfidence, decisions about war, gender, and testosterone. Here we report that, in experimental wargames: (i) people are overconfident about their expectations of success; (ii) those who are more overconfident are more likely to attack; (iii) overconfidence and attacks are more pronounced among males than females; and (iv) testosterone is related to expectations of success, but not within gender, so its influence on overconfidence cannot be distinguished from any other gender specific factor. Overall, these results constitute the first empirical support of recent theoretical work linking overconfidence and war. PMID:16959643

  14. Experimental evidence for both progressive and simultaneous shear during quasistatic compression of a bulk metallic glass

    NASA Astrophysics Data System (ADS)

    Wright, Wendelin J.; Liu, Yun; Gu, Xiaojun; Van Ness, Katherine D.; Robare, Steven L.; Liu, Xin; Antonaglia, James; LeBlanc, Michael; Uhl, Jonathan T.; Hufnagel, Todd C.; Dahmen, Karin A.

    2016-02-01

    Two distinct types of slip events occur during serrated plastic flow of bulk metallic glasses. These events are distinguished not only by their size but also by distinct stress drop rate profiles. Small stress drop serrations have fluctuating stress drop rates (with maximum stress drop rates ranging from 0.3-1 GPa/s), indicating progressive or intermittent propagation of a shear band. The large stress drop serrations are characterized by sharply peaked stress drop rate profiles (with maximum stress drop rates of 1-100 GPa/s). The propagation of a large slip is preceded by a slowly rising stress drop rate that is presumably due to the percolation of slipping weak spots prior to the initiation of shear over the entire shear plane. The onset of the rapid shear event is accompanied by a burst of acoustic emission. These large slips correspond to simultaneous shear with uniform sliding as confirmed by direct high-speed imaging and image correlation. Both small and large slip events occur throughout plastic deformation. The significant differences between these two types require that they be carefully distinguished in both modeling and experimental efforts.

  15. First Direct Experimental Evidence of Loss Cone Scattering of Energetic Electrons by Plasmaspheric Hiss

    NASA Astrophysics Data System (ADS)

    Breneman, A. W.; Halford, A.; Millan, R. M.; Wygant, J. R.; Cattell, C. A.; Woodger, L. A.; Hospodarsky, G. B.; Fennell, J.; Sample, J. G.; Kletzing, C.; Kurth, W. S.; Ukhorskiy, A. Y.; Goldstein, J.; Bonnell, J. W.

    2014-12-01

    A number of physical mechanisms have been identified as potentially important for causing Van Allen radiation belt electron loss. Over 40 years ago it was suggested that loss caused by electron interaction with an electromagnetic plasma wave called plasmaspheric hiss dominates electron loss in the outer portion of the radiation belt that overlaps with a high density region called the plasmasphere. Motivated by the difficulty of observing this loss process with particle detectors on satellites, the Balloon Array for Radiation Belt Relativistic Electron Losses (BARREL) campaign was designed to observe bremsstrahlung x-rays generated by electrons colliding with atmospheric neutrals after removal from the radiation belts. By comparison of x-ray counts to magnetically conjugate plasmaspheric hiss observed on the Van Allen Probes we provide the first direct experimental verification that hiss removes electrons from the radiation belts. X-ray counts and hiss amplitude show similar variation on timescales ranging from minutes to hours. A surprising result is that 1-20 min period fluctuations of x-rays and hiss are coherent on scales comparable to the size of the plasmasphere, far exceeding the few km scale on which wave-particle interactions operate, and establishing that the loss process has global effects on the radiation belts.

  16. Experimental evidence for climatically controlled changes between lateral erosion and incision of actively uplifting folds

    NASA Astrophysics Data System (ADS)

    Bufe, Aaron; Paola, Chris; Burbank, Douglas; Thompson, Jessica

    2016-04-01

    The understanding of the incision and lateral erosion of rivers provides key data for the interpretation of landscapes as recorders of climatic and tectonic processes. We present results from six physical experiments on the erosion of a simple growing fold by antecedent streams. By varying uplift rates, sediment flux, and the width of alluvial fans upstream of the uplift, we produced a range of morphologies from narrow canyons through the fold to erosion of the entire uplift. The fraction of the uplift that was beveled by the river can be predicted by a dimensionless parameter linking the mobility of channels (strongly dependent on the sediment flux) and the rock-uplift rate. We apply these findings to a series of active folds in the foreland of the Tian Shan in NW China. Whereas the folds are incised today, they preserve uplifted, kilometer-wide beveled platforms. In the light of the experimental results, lateral migration rates required to explain such extensive beveling are similar to the lateral mobility of alluvial streams in areas much wetter than the presently arid northwestern Tarim Basin and suggest that major changes in water and sediment influxes are the probable cause of switches between lateral erosion and incision of active uplifts in the foreland of the Tian Shan. This finding is supported by the clustering of ages of fluvial terrace and alluvial fan deposition in that region.

  17. Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils

    NASA Astrophysics Data System (ADS)

    Colleary, Caitlin; Dolocan, Andrei; Gardner, James; Singh, Suresh; Wuttke, Michael; Rabenstein, Renate; Habersetzer, Jörg; Schaal, Stephan; Feseha, Mulugeta; Clemens, Matthew; Jacobs, Bonnie F.; Currano, Ellen D.; Jacobs, Louis L.; Lyng Sylvestersen, Rene; Gabbott, Sarah E.; Vinther, Jakob

    2015-10-01

    In living organisms, color patterns, behavior, and ecology are closely linked. Thus, detection of fossil pigments may permit inferences about important aspects of ancient animal ecology and evolution. Melanin-bearing melanosomes were suggested to preserve as organic residues in exceptionally preserved fossils, retaining distinct morphology that is associated with aspects of original color patterns. Nevertheless, these oblong and spherical structures have also been identified as fossilized bacteria. To date, chemical studies have not directly considered the effects of diagenesis on melanin preservation, and how this may influence its identification. Here we use time-of-flight secondary ion mass spectrometry to identify and chemically characterize melanin in a diverse sample of previously unstudied extant and fossil taxa, including fossils with notably different diagenetic histories and geologic ages. We document signatures consistent with melanin preservation in fossils ranging from feathers, to mammals, to amphibians. Using principal component analyses, we characterize putative mixtures of eumelanin and phaeomelanin in both fossil and extant samples. Surprisingly, both extant and fossil amphibians generally exhibit melanosomes with a mixed eumelanin/phaeomelanin composition rather than pure eumelanin, as assumed previously. We argue that experimental maturation of modern melanin samples replicates diagenetic chemical alteration of melanin observed in fossils. This refutes the hypothesis that such fossil microbodies could be bacteria, and demonstrates that melanin is widely responsible for the organic soft tissue outlines in vertebrates found at exceptional fossil localities, thus allowing for the reconstruction of certain aspects of original pigment patterns.

  18. No evidence of complementary water use along a plant species richness gradient in temperate experimental grasslands.

    PubMed

    Bachmann, Dörte; Gockele, Annette; Ravenek, Janneke M; Roscher, Christiane; Strecker, Tanja; Weigelt, Alexandra; Buchmann, Nina

    2015-01-01

    Niche complementarity in resource use has been proposed as a key mechanism to explain the positive effects of increasing plant species richness on ecosystem processes, in particular on primary productivity. Since hardly any information is available for niche complementarity in water use, we tested the effects of plant diversity on spatial and temporal complementarity in water uptake in experimental grasslands by using stable water isotopes. We hypothesized that water uptake from deeper soil depths increases in more diverse compared to low diverse plant species mixtures. We labeled soil water in 8 cm (with 18O) and 28 cm depth (with ²H) three times during the 2011 growing season in 40 temperate grassland communities of varying species richness (2, 4, 8 and 16 species) and functional group number and composition (legumes, grasses, tall herbs, small herbs). Stable isotope analyses of xylem and soil water allowed identifying the preferential depth of water uptake. Higher enrichment in 18O of xylem water than in ²H suggested that the main water uptake was in the upper soil layer. Furthermore, our results revealed no differences in root water uptake among communities with different species richness, different number of functional groups or with time. Thus, our results do not support the hypothesis of increased complementarity in water use in more diverse than in less diverse communities of temperate grassland species. PMID:25587998

  19. Experimental evidence of incomplete fluorescence quenching of pyrene bound to humic substances: implications for Koc measurements.

    PubMed

    Shirshin, E A; Budylin, G S; Grechischeva, N Yu; Fadeev, V V; Perminova, I V

    2016-07-01

    Fluorescence quenching (FQ) is extensively used for quantitative assessment of partition coefficients (KOC) of polycyclic aromatic hydrocarbons (PAHs) to natural organic materials - humic substances (HS). The presence of bound PAHs with incompletely quenched fluorescence would lead to underestimation of the KOC values measured by this technique. The goal of this work was to prove the validity of this assumption using an original experimental setup, which implied FQ measurements upon excitation into two distinct vibronically coupled electronic states. Pyrene was used as a fluorescent probe, and aquatic fulvic acid (SRFA) and leonardite humic acid (CHP) were used as the humic materials with low and high binding affinity for pyrene, respectively. Excitation of pyrene into the forbidden (S0-S1) and allowed (S0-S2) electronic states yielded two pairs of nonidentical FQ curves. This was indicative of incomplete quenching of the bound pyrene, and the divergence of the two FQ curves was much more pronounced for CHP as compared to SRFA. The two component model of fluorescence response formation was proposed to estimate the KOC values from the data obtained. The resulting pyrene KOC value for CHP (220 ± 20) g L(-1) was a factor 3 higher compared to the KOC value determined with the use of the Stern-Volmer formalism (68 ± 2) g L(-1). At the same time for aquatic FA the difference in FQ curves was almost negligible, which enables the use of the Stern-Volmer formalism for weakly interacting HS and PAHs. PMID:27279258

  20. Experimental evidence for beneficial effects of projected climate change on hibernating amphibians.

    PubMed

    Üveges, Bálint; Mahr, Katharina; Szederkényi, Márk; Bókony, Veronika; Hoi, Herbert; Hettyey, Attila

    2016-01-01

    Amphibians are the most threatened vertebrates today, experiencing worldwide declines. In recent years considerable effort was invested in exposing the causes of these declines. Climate change has been identified as such a cause; however, the expectable effects of predicted milder, shorter winters on hibernation success of temperate-zone Amphibians have remained controversial, mainly due to a lack of controlled experimental studies. Here we present a laboratory experiment, testing the effects of simulated climate change on hibernating juvenile common toads (Bufo bufo). We simulated hibernation conditions by exposing toadlets to current (1.5 °C) or elevated (4.5 °C) hibernation temperatures in combination with current (91 days) or shortened (61 days) hibernation length. We found that a shorter winter and milder hibernation temperature increased survival of toads during hibernation. Furthermore, the increase in temperature and shortening of the cold period had a synergistic positive effect on body mass change during hibernation. Consequently, while climate change may pose severe challenges for amphibians of the temperate zone during their activity period, the negative effects may be dampened by shorter and milder winters experienced during hibernation. PMID:27229882

  1. Experimental evidence for beneficial effects of projected climate change on hibernating amphibians

    PubMed Central

    Üveges, Bálint; Mahr, Katharina; Szederkényi, Márk; Bókony, Veronika; Hoi, Herbert; Hettyey, Attila

    2016-01-01

    Amphibians are the most threatened vertebrates today, experiencing worldwide declines. In recent years considerable effort was invested in exposing the causes of these declines. Climate change has been identified as such a cause; however, the expectable effects of predicted milder, shorter winters on hibernation success of temperate-zone Amphibians have remained controversial, mainly due to a lack of controlled experimental studies. Here we present a laboratory experiment, testing the effects of simulated climate change on hibernating juvenile common toads (Bufo bufo). We simulated hibernation conditions by exposing toadlets to current (1.5 °C) or elevated (4.5 °C) hibernation temperatures in combination with current (91 days) or shortened (61 days) hibernation length. We found that a shorter winter and milder hibernation temperature increased survival of toads during hibernation. Furthermore, the increase in temperature and shortening of the cold period had a synergistic positive effect on body mass change during hibernation. Consequently, while climate change may pose severe challenges for amphibians of the temperate zone during their activity period, the negative effects may be dampened by shorter and milder winters experienced during hibernation. PMID:27229882

  2. Experimental evidence for American bullfrog (Lithobates catesbeianus) susceptibility to chytrid fungus (Batrachochytrium dendrobatidis).

    PubMed

    Gervasi, Stephanie S; Urbina, Jenny; Hua, Jessica; Chestnut, Tara; A Relyea, Rick; R Blaustein, Andrew

    2013-06-01

    The emerging fungal pathogen, Batrachochytrium dendrobatidis (Bd), has been associated with global amphibian population declines and extinctions. American bullfrogs (Lithobates catesbeianus) are widely reported to be a tolerant host and a carrier of Bd that spreads the pathogen to less tolerant hosts. Here, we examined whether bullfrogs raised from eggs to metamorphosis in outdoor mesocosms were susceptible to Bd. We experimentally exposed metamorphic juveniles to Bd in the laboratory and compared mortality rates of pathogen-exposed animals to controls (non-exposed) in two separate experiments; one using a Bd strain isolated from a Western toad and another using a strain isolated from an American bullfrog. We wanted to examine whether metamorphic bullfrogs were susceptible to either of these strains. We show that bullfrogs were susceptible to one strain of Bd and not the other. In both experiments, infection load detected in the skin decreased over time, suggesting that metamorphic bullfrogs from some populations may be inefficient long-term carriers of Bd. PMID:23539129

  3. Regulation of Sclerostin Production in Human Male Osteocytes by Androgens: Experimental and Clinical Evidence.

    PubMed

    Di Nisio, Andrea; De Toni, Luca; Speltra, Elena; Rocca, Maria Santa; Taglialavoro, Giuseppe; Ferlin, Alberto; Foresta, Carlo

    2015-12-01

    In this study we aimed to elucidate a possible role of T in the regulation of sclerostin, a glycoprotein secreted by osteocytes known to regulate bone mass. To this end, we evaluated the effect of T stimulation on sclerostin production and gene expression in human cultured osteocytes. In addition, we evaluated serum sclerostin levels in a cohort of 20 hypogonadal male patients, compared with 20 age-matched eugonadal controls. Stimulation with DHT decreased sclerostin expression in cultured osteocytes in a time- and dose-dependent manner. Confirming a direct androgen receptor-mediated effect on sclerostin production, flutamide coincubation and silencing of androgen receptor gene in osteocytes abolished the DHT effects. In addition, hypogonadal patients showed higher serum sclerostin levels with respect to controls (145.87 ± 50.83 pg/mL vs 84.02 ± 32.15 pg/mL; P < .001) and in both probands and controls, serum T levels were negatively correlated with sclerostin (R = -0.664, P = 0.007, and R = -0.447, P = .045, respectively). Finally, multiple stepwise regression analysis showed that T represented the only independent predictor of sclerostin levels. In conclusion, by showing a direct correlation between T and sclerostin, both in vivo and in vitro, this study adds further support to the emerging clinical and experimental studies focusing on sclerostin as a therapeutic target for osteoporosis treatment. PMID:26393301

  4. Yes, it turns: experimental evidence of pearl rotation during its formation.

    PubMed

    Gueguen, Yannick; Czorlich, Yann; Mastail, Max; Le Tohic, Bruno; Defay, Didier; Lyonnard, Pierre; Marigliano, Damien; Gauthier, Jean-Pierre; Bari, Hubert; Lo, Cedrik; Chabrier, Sébastien; Le Moullac, Gilles

    2015-07-01

    Cultured pearls are human creations formed by inserting a nucleus and a small piece of mantle tissue into a living shelled mollusc, usually a pearl oyster. Although many pearl observations intuitively suggest a possible rotation of the nucleated pearl inside the oyster, no experimental demonstration of such a movement has ever been done. This can be explained by the difficulty of observation of such a phenomenon in the tissues of a living animal. To investigate this question of pearl rotation, a magnetometer system was specifically engineered to register magnetic field variations with magnetic sensors from movements of a magnetic nucleus inserted in the pearl oyster. We demonstrated that a continuous movement of the nucleus inside the oyster starts after a minimum of 40 days post-grafting and continues until the pearl harvest. We measured a mean angular speed of 1.27° min(-1) calculated for four different oysters. Rotation variability was observed among oysters and may be correlated to pearl shape and defects. Nature's ability to generate so amazingly complex structures like a pearl has delivered one of its secrets. PMID:26587271

  5. Experimental evidence of beam-foil plasma creation during ion-solid interaction

    NASA Astrophysics Data System (ADS)

    Sharma, Prashant; Nandi, Tapan

    2016-08-01

    Charge state evolution of the energetic projectile ions during the passage through thin carbon foils has been revisited using the X-ray spectroscopy technique. Contributions from the bulk and the solid surface in the charge changing processes have been segregated by measuring the charge state distribution of the projectile ions in the bulk of the target during the ion-solid interaction. Interestingly, the charge state distribution measured in the bulk exhibits Lorentzian profile in contrast to the well-known Gaussian structure observed using the electromagnetic methods and the theoretical predictions. The occurrence of such behavior is a direct consequence of the imbalance between charge changing processes, which has been seen in various cases of the laboratory plasma. It suggests that the ion-solid collisions constitute high-density, localized plasma in the bulk of the solid target, called the beam-foil plasma. This condensed beam-foil plasma is similar to the high-density solar and stellar plasma which may have practical implementations in various fields, in particular, plasma physics and nuclear astrophysics. The present work suggests further modification in the theoretical charge state distribution calculations by incorporating the plasma coupling effects during the ion-solid interactions. Moreover, the multi-electron capture from the target exit surface has been confirmed through comparison between experimentally measured and theoretically predicted values of the mean charge state of the projectile ions.

  6. Behavioral response to contamination risk information in a spatially explicit groundwater environment: Experimental evidence

    NASA Astrophysics Data System (ADS)

    Li, Jingyuan; Michael, Holly A.; Duke, Joshua M.; Messer, Kent D.; Suter, Jordan F.

    2014-08-01

    This paper assesses the effectiveness of aquifer monitoring information in achieving more sustainable use of a groundwater resource in the absence of management policy. Groundwater user behavior in the face of an irreversible contamination threat is studied by applying methods of experimental economics to scenarios that combine a physics-based, spatially explicit, numerical groundwater model with different representations of information about an aquifer and its risk of contamination. The results suggest that the threat of catastrophic contamination affects pumping decisions: pumping is significantly reduced in experiments where contamination is possible compared to those where pumping cost is the only factor discouraging groundwater use. The level of information about the state of the aquifer also affects extraction behavior. Pumping rates differ when information that synthesizes data on aquifer conditions (a "risk gauge") is provided, despite invariant underlying economic incentives, and this result does not depend on whether the risk information is location-specific or from a whole aquifer perspective. Interestingly, users increase pumping when the risk gauge signals good aquifer status compared to a no-gauge treatment. When the gauge suggests impending contamination, however, pumping declines significantly, resulting in a lower probability of contamination. The study suggests that providing relatively simple aquifer condition guidance derived from monitoring data can lead to more sustainable use of groundwater resources.

  7. Processed meat and colorectal cancer: a review of epidemiologic and experimental evidence

    PubMed Central

    Santarelli, Raphaëlle L.; Pierre, Fabrice; Corpet, Denis E.

    2008-01-01

    Processed meat intake may be involved in the etiology of colorectal cancer, a major cause of death in affluent countries. The epidemiologic studies published to date conclude that the excess risk in the highest category of processed meat-eaters is comprised between 20 and 50% compared with non-eaters. In addition, the excess risk per gram of intake is clearly higher than that of fresh red meat. Several hypotheses, which are mainly based on studies carried out on red meat, may explain why processed meat intake is linked to cancer risk. Those that have been tested experimentally are (i) that high-fat diets could promote carcinogenesis via insulin resistance or fecal bile acids; (ii) that cooking meat at a high temperature forms carcinogenic heterocyclic amines and polycyclic aromatic hydrocarbons; (iii) that carcinogenic N-nitroso compounds are formed in meat and endogenously; (iv) that heme iron in red meat can promote carcinogenesis because it increases cell proliferation in the mucosa, through lipoperoxidation and/or cytotoxicity of fecal water. Nitrosation might increase the toxicity of heme in cured products. Solving this puzzle is a challenge that would permit to reduce cancer load by changing the processes rather than by banning processed meat. PMID:18444144

  8. Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils

    PubMed Central

    Colleary, Caitlin; Dolocan, Andrei; Gardner, James; Singh, Suresh; Wuttke, Michael; Rabenstein, Renate; Habersetzer, Jörg; Schaal, Stephan; Feseha, Mulugeta; Clemens, Matthew; Jacobs, Bonnie F.; Currano, Ellen D.; Jacobs, Louis L.; Sylvestersen, Rene Lyng; Gabbott, Sarah E.; Vinther, Jakob

    2015-01-01

    In living organisms, color patterns, behavior, and ecology are closely linked. Thus, detection of fossil pigments may permit inferences about important aspects of ancient animal ecology and evolution. Melanin-bearing melanosomes were suggested to preserve as organic residues in exceptionally preserved fossils, retaining distinct morphology that is associated with aspects of original color patterns. Nevertheless, these oblong and spherical structures have also been identified as fossilized bacteria. To date, chemical studies have not directly considered the effects of diagenesis on melanin preservation, and how this may influence its identification. Here we use time-of-flight secondary ion mass spectrometry to identify and chemically characterize melanin in a diverse sample of previously unstudied extant and fossil taxa, including fossils with notably different diagenetic histories and geologic ages. We document signatures consistent with melanin preservation in fossils ranging from feathers, to mammals, to amphibians. Using principal component analyses, we characterize putative mixtures of eumelanin and phaeomelanin in both fossil and extant samples. Surprisingly, both extant and fossil amphibians generally exhibit melanosomes with a mixed eumelanin/phaeomelanin composition rather than pure eumelanin, as assumed previously. We argue that experimental maturation of modern melanin samples replicates diagenetic chemical alteration of melanin observed in fossils. This refutes the hypothesis that such fossil microbodies could be bacteria, and demonstrates that melanin is widely responsible for the organic soft tissue outlines in vertebrates found at exceptional fossil localities, thus allowing for the reconstruction of certain aspects of original pigment patterns. PMID:26417094

  9. Experimental evidence for modifying the current physical model for ice accretion on aircraft surfaces

    NASA Technical Reports Server (NTRS)

    Olsen, W.; Walker, E.

    1986-01-01

    Closeup movies, still photographs, and other experimental data suggest that the current physical model for ice accretion needs significant modification. At aircraft airspeeds there was no flow of liquid over the surface of the ice after a short initial flow, even at barely subfreezing temperatures. Instead, there were very large stationary drops on the ice surface that lose water from their bottoms by freezing and replenish their liquid by catching the microscopic cloud droplets. This observation disagrees with the existing physical model, which assumes there is a thin liquid film continuously flowing over the ice surface. With no such flow, the freezing-fraction concept of the model fails when a mass balance is performed on the surface water. Rime ice does, as the model predicts, form when the air temperature is low enough to cause the cloud droplets to freeze almost immediately on impact. However, the characteristic shapes of horn-glaze ice or rime ice are primarily caused by the ice shape affecting the airflow locally and consequently the droplet catch and the resulting ice shape. Ice roughness greatly increases the heat transfer coefficient, stops the movement of drops along the surface, and may also affect the airflow initially and thereby the droplet catch. At high subreezing temperatures the initial flow and shedding of surface drops have a large effect on the ice shape. At the incipient freezing limit, no ice forms.

  10. Lexical plasticity in early bilinguals does not alter phoneme categories: II. Experimental evidence.

    PubMed

    Sebastián-Gallés, Núria; Vera-Constán, Fátima; Larsson, Johan P; Costa, Albert; Deco, Gustavo

    2009-12-01

    When listening to modified speech, either naturally or artificially altered, the human perceptual system rapidly adapts to it. There is some debate about the nature of the mechanisms underlying this adaptation. Although some authors propose that listeners modify their prelexical representations, others assume changes at the lexical level. Recently, Larsson, Vera, Sebastian-Galles, and Deco [Lexical plasticity in early bilinguals does not alter phoneme categories: I. Neurodynamical modelling. Journal of Cognitive Neuroscience, 20, 76-94, 2008] proposed a biologically plausible computational model to account for some existing data, one which successfully modeled how long-term exposure to a dialect triggers the creation of new lexical entries. One specific prediction of the model was that prelexical (phoneme) representations should not be affected by dialectal exposure (as long as the listener is exposed to both standard and dialectal pronunciations). Here we present a series of experiments testing the predictions of the model. Native listeners of Catalan, with extended exposure to Spanish-accented Catalan, were tested on different auditory lexical decision tasks and phoneme discrimination tasks. Behavioral and electrophysiological recordings were obtained. The results supported the predictions of our model. On the one hand, both error rates and N400 measurements indicated the existence of alternative lexical entries for dialectal varieties. On the other hand, no evidence of alterations at the phoneme level, either in the behavioral discrimination task or in the electrophysiological measurement (MMN), could be detected. The results of the present study are compared with those obtained in short-term laboratory exposures in an attempt to provide an integrative account. PMID:18855552

  11. 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. PMID:22815066

  12. Experimental Evidence for Weathering and Martian Sulfate Formation Under Extremely Cold Weather-Limited Environments

    NASA Technical Reports Server (NTRS)

    Niles, Paul B.; Golden, D. C.; Michalski, J.

    2013-01-01

    High resolution photography and spectroscopy of the martian surface (MOC, HiRISE) from orbit has revolutionized our view of Mars with one of the most important discoveries being wide-spread layered sedimentary deposits associated with sulfate minerals across the low to mid latitude regions of Mars [1, 2]. The mechanism for sulfate formation on Mars has been frequently attributed to playa-like evaporative environments under prolonged warm conditions [3]. However, there are several problems with the presence of prolonged surface temperatures on Mars above 273 K during the Noachian including the faint young Sun [4] and the presence of suitable greenhouse gases [5]. The geomorphic evidence for early warm conditions may instead be explained by periodic episodes of warming rather than long term prolonged warm temperatures [6]. An alternate view of the ancient martian climate contends that prolonged warm temperatures were never present and that the atmosphere and climate has been similar to modern conditions throughout most of its history [6]. This view is more consistent with the climate models, but has had a difficult time explaining the sedimentary history of Mars and in particular the presence of sulfate minerals. We suggest here that mixtures of atmospheric aerosols, ice, and dust have the potential for creating small films of cryo-concentrated acidic solutions that may represent an important unexamined environment for understanding weathering processes on Mars [7, 8]. This study seeks to test whether sulfate formation may be possible at temperatures well below 0 C in water limited environments removing the need for prolonged warm periods to form sulfates on early Mars.

  13. Parents influence asymmetric sibling competition: experimental evidence with partially dependent young.

    PubMed

    Smiseth, Per T; Ward, Richard J S; Moore, Allen J

    2007-12-01

    evidence of asymmetric sibling competition when parents were absent and offspring obtained resources solely by self-feeding. PMID:18229851

  14. 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.

  15. Short Lag Times for Invasive Tropical Plants: Evidence from Experimental Plantings in Hawai'i

    PubMed Central

    Daehler, Curtis C.

    2009-01-01

    Background The lag time of an invasion is the delay between arrival of an introduced species and its successful spread in a new area. To date, most estimates of lag times for plants have been indirect or anecdotal, and these estimates suggest that plant invasions are often characterized by lag times of 50 years or more. No general estimates are available of lag times for tropical plant invasions. Historical plantings and documentation were used to directly estimate lag times for tropical plant invasions in Hawai'i. Methodology/Principal Findings Historical planting records for the Lyon Arboretum dating back to 1920 were examined to identify plants that have since become invasive pests in the Hawaiian Islands. Annual reports describing escape from plantings were then used to determine the lag times between initial plantings and earliest recorded spread of the successful invaders. Among 23 species that eventually became invasive pests, the average lag time between introduction and first evidence of spread was 14 years for woody plants and 5 years for herbaceous plants. Conclusions/Significance These direct estimates of lag times are as much as an order of magnitude shorter than previous, indirect estimates, which were mainly based on temperate plants. Tropical invaders may have much shorter lag times than temperate species. A lack of direct and deliberate observations may have also inflated many previous lag time estimates. Although there have been documented cases of long lag times due to delayed arrival of a mutualist or environmental changes over time, this study suggests that most successful invasions are likely to begin shortly after arrival of the plant in a suitable habitat, at least in tropical environments. Short lag times suggest that controlled field trials may be a practical element of risk assessment for plant introductions. PMID:19223966

  16. Direct evidence of "damage accumulation" in cement mantles surrounding femoral hip stems retrieved at autopsy: cement damage correlates with duration of use and BMI.

    PubMed

    Race, A; Miller, M A; Izant, T H; Mann, K A

    2011-09-01

    The "damage accumulation" phenomenon has not been quantitatively demonstrated in clinical cement mantles surrounding femoral hip stems. We stained transverse sections of 11 postmortem retrieved femoral hip components fixed with cement using fluorescent dye-penetrant and quantified cement damage, voids, and cement-bone interface gaps in epifluorescence and white light micrographs. Crack density (Cr.Dn), crack length-density (Cr.Ln.Dn), porosity, and cement-bone interface gap fraction (c/b-gap%) were calculated, normalized by mantle area. Multiple regression tests showed that cement damage (Cr.Ln.Dn. & Cr.Dn.) was significantly positively correlated (r(2)=0.98, p<0.001) with "duration of use" and body mass index ("BMI") but not cement mantle "porosity". There were significant interactions: "duration of use"*"BMI" was strongly predictive (p<0.005) of Cr.Dn.; and "duration of use"*"porosity" was predictive (p=0.04) of Cr.Ln.Dn. Stem related cracks accounted for approximately one fifth of Cr.Dn and one third of Cr.Ln.Dn. The mean c/b-gap% was 13.8% but it did not correlate (r(2)=0.01, p=0.8) with duration of use. We concluded that duration-dependent fatigue damage accumulation occurred during in vivo use. BMI strongly influenced cement crack length and the rate of new crack formation over time. Voids did not increase the rate of crack initiation but appeared to have promoted crack growth over time. Although not progressive, substantial bone resorption at the cement-bone interface appeared to be common. PMID:21802085

  17. 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

  18. 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.

  19. Experimental evidence that dispersal drives ant community assembly in human-altered ecosystems.

    PubMed

    King, Joshua R; Tschinkel, Walter R

    2016-01-01

    A key shortcoming in our understanding of exotic species' success is that it is not known how post-introduction dispersal contributes to the success of exotic species and the reassembly of invaded communities. Exotic and native species face poorly understood competition-colonization trade-offs in heterogeneous landscapes of natural and anthropogenic habitats. We conducted three experiments that tested how ant queen behavior during dispersal affects community composition. Using experimental plots, we tested whether (1) different types of habitat disturbance and (2) different sizes of habitat disturbance affected the abundance of newly mated queens landing in the plots. The three most abundant species captured were the exotic fire ant Solenopsis invicta, and the native species Brachymyrmex depilis, and S. pergandei, respectively. When queens were considered collectively, more queens landed in plowed, sand-added, and roadside plots than in control or mow plots, in other words, in the more heavily disturbed plots. We also tested (3) the effect of habitat manipulations on the survival of newly mated fire ant queens (Solenopsis invicta). Soil disturbance (tilling), lack of shade, and removal (poisoning) of the ant community resulted in the greatest fire ant colony survivorship. Collectively, experiments revealed that both exotic and native newly mated ant queens select open, human-altered ecosystems for founding new colonies. The selection of such habitats by fire ant queens leads to their successful colony founding and ultimately to their dominance in those habitats. Selection of disturbed habitats is therefore advantageous for exotic species but is an ecological trap for native species because they do not often succeed in founding colonies in these habitats. PMID:27008792

  20. Experimental evidence for enhanced top-down control of freshwater macrophytes with nutrient enrichment.

    PubMed

    Bakker, Elisabeth S; Nolet, Bart A

    2014-11-01

    The abundance of primary producers is controlled by bottom-up and top-down forces. Despite the fact that there is consensus that the abundance of freshwater macrophytes is strongly influenced by the availability of resources for plant growth, the importance of top-down control by vertebrate consumers is debated, because field studies yield contrasting results. We hypothesized that these bottom-up and top-down forces may interact, and that consumer impact on macrophyte abundance depends on the nutrient status of the water body. To test this hypothesis, experimental ponds with submerged vegetation containing a mixture of species were subjected to a fertilization treatment and we introduced consumers (mallard ducks, for 8 days) on half of the ponds in a full factorial design. Over the whole 66-day experiment fertilized ponds became dominated by Elodea nuttallii and ponds without extra nutrients by Chara globularis. Nutrient addition significantly increased plant N and P concentrations. There was a strong interactive effect of duck presence and pond nutrient status: macrophyte biomass was reduced (by 50%) after the presence of the ducks on fertilized ponds, but not in the unfertilized ponds. We conclude that nutrient availability interacts with top-down control of submerged vegetation. This may be explained by higher plant palatability at higher nutrient levels, either by a higher plant nutrient concentration or by a shift towards dominance of more palatable plant species, resulting in higher consumer pressure. Including nutrient availability may offer a framework to explain part of the contrasting field observations of consumer control of macrophyte abundance. PMID:25194349

  1. Ultrafine spherical quartz formation during seismic fault slip: Natural and experimental evidence and its implications

    NASA Astrophysics Data System (ADS)

    Kuo, Li-Wei; Song, Yen-Fang; Yang, Che-Ming; Song, Sheng-Rong; Wang, Chun-Chieh; Dong, Jia-Jyun; Suppe, John; Shimamoto, Toshihiko

    2015-11-01

    In recent works on the determination of pseudotachylyte within the principal slip zone (PSZ) of the Chelungpu fault (Taiwan), we demonstrated that frictional melting occurred at shallow depths during the 1999 Mw 7.6 Chi-Chi earthquake. Thus, the characteristics of melts are of paramount importance to investigate processes controlling dynamic fault mechanics during seismic slips. We conducted rock friction experiments on siltstone recovered from the Taiwan Chelungpu fault Drilling Project (TCDP) at a slip rate of 1.3 m/s and a normal stress of 1 MPa. Here we not only target to characterize experimental pseudotachylyte and evaluate the associated frictional behavior, but also compare it with natural frictional melts of TCDP. Our results show that (1) initial shear stress drop was related to the generation of low viscosity melt patches, (2) the evolution of shear stress in the postmelting regime was congruent with frictional melt rheology, and (3) the slip strengthening presumably resulted from the extremely low content of water of the frictional melt. In particular, the state-of-art of in situ synchrotron analyses (X-ray diffraction and Transmission X-ray Microscope) determine the presence of ultrafine spherical quartz (USQ) grains (~ 10 nm to 50 nm) in the glassy matrices presumably produced at high temperature. Our observations confirm that the USQ grains formed in rock friction experiments do occur in natural faults. We surmise the USQ is the result of frictional melting on siltstone and represents the latest slip zones of the Chelungpu fault, and further infer that the viscous melts may terminate seismic slips at shallow crustal conditions.

  2. pH Transients in hydroxyapatite chromatography columns-experimental evidence and phenomenological modeling.

    PubMed

    Bankston, Theresa E; Dattolo, Laura; Carta, Giorgio

    2010-04-01

    Hydroxyapatite (HAP) columns, widely used for chromatographic separation of proteins and other biomolecules because of their unique selectivity and ability to resolve complex mixtures, exhibit limited stability at acidic conditions requiring careful control of pH. Even with buffered solutions, however, unintended pH transients can occur when the salt concentration varies. For example, the pH temporarily decreases below the feed value when the salt concentration increases and increases above the feed value when the salt concentration is decreased. The intensity and duration of these transients depend on the particular buffer used and the magnitude of the salt concentration step, but in extreme cases the pH can drop by as much as 1.5 pH units creating conditions where the HAP stability is potentially compromised. This work examines the mechanisms leading to pH transients in HAP columns generated by salt steps. The pH excursions are similar to those observed for weak cation exchange columns, but are accompanied by a transient evolution of phosphate which temporarily decreases below the feed value when the salt concentration is increased and increases sharply when the salt concentration is reduced before returning to the feed value. A phenomenological model is developed to describe this behavior by considering the reversible uptake of sodium ions by the P-sites and binding of phosphate ions by the C-sites. The interplay of these two adsorption mechanisms results in complex pH patterns that are consistent with those observed experimentally. In addition to helping understand the underlying mechanisms, the model also provides a useful tool to predict the effects of different buffers and salt concentration and develop corrective measures that can reduce the intensity and duration of the pH transients such as the addition of unretained co-buffers. PMID:20193952

  3. Thiol groups controls on arsenite binding by organic matter: new experimental and modeling evidence.

    PubMed

    Catrouillet, Charlotte; Davranche, Mélanie; Dia, Aline; Bouhnik-Le Coz, Martine; Pédrot, Mathieu; Marsac, Rémi; Gruau, Gérard

    2015-12-15

    Although it has been suggested that several mechanisms can describe the direct binding of As(III) to organic matter (OM), more recently, the thiol functional group of humic acid (HA) was shown to be an important potential binding site for As(III). Isotherm experiments on As(III) sorption to HAs, that have either been grafted with thiol or not, were thus conducted to investigate the preferential As(III) binding sites. There was a low level of binding of As(III) to HA, which was strongly dependent on the abundance of the thiols. Experimental datasets were used to develop a new model (the modified PHREEQC-Model VI), which defines HA as a group of discrete carboxylic, phenolic and thiol sites. Protonation/deprotonation constants were determined for each group of sites (pKA=4.28±0.03; ΔpKA=2.13±0.10; pKB=7.11±0.26; ΔpKB=3.52±0.49; pKS=5.82±0.052; ΔpKS=6.12±0.12 for the carboxylic, phenolic and thiols sites, respectively) from HAs that were either grafted with thiol or not. The pKS value corresponds to that of single thiol-containing organic ligands. Two binding models were tested: the Mono model, which considered that As(III) is bound to the HA thiol site as monodentate complexes, and the Tri model, which considered that As(III) is bound as tridentate complexes. A simulation of the available literature datasets was used to validate the Mono model, with logKMS=2.91±0.04, i.e. the monodentate hypothesis. This study highlighted the importance of thiol groups in OM reactivity and, notably, determined the As(III) concentration bound to OM (considering that Fe is lacking or at least negligible) and was used to develop a model that is able to determine the As(III) concentrations bound to OM. PMID:26348657

  4. Experimental evidence of thermo-mechanical pressurization of faults during earthquakes

    NASA Astrophysics Data System (ADS)

    Violay, Marie; Di Toro, Giulio; Nielsen, Stefan; Spagnuolo, Elena; Burg, Jean-Pierre

    2015-04-01

    Earthquakes occur while fault strength decreases with increasing slip and slip rate. Thermo-mechanical pressurization of pore fluids induced by frictional heating during seismic slip is one of the possible mechanisms responsible for fault dynamic weakening. However, has not yet been observed in the laboratory. To investigate seismic slip in the presence of pore fluids, 26 friction experiments were conducted at room temperature on hollow cylinders (50/30 mm external/internal diameter) of Etna basalt (1) under room-dry conditions or immersed in water under either (2) drained conditions (constant pore pressure, preventing fluid pressurization), and (3) undrained conditions (constant pore volume). Experiments were performed by spinning two basalt cylinders with the rotary shear machine (SHIVA, INGV Rome) at target slip rates (V) of 3 m/s, displacements (δ) from 4 m to 6 m, normal stress (σn) ranging from 15 to 35 MPa and initial pore fluid pressure (Pf) of 5 MPa.The experimental data are compared with those obtained from carbonate-bearing rocks (Carrara marble). In all the experiments, the coefficient of friction μ decayed exponentially from a peak value (μp = 0.55 ∓ 0.07) at about the initiation of slip towards a steady-state value μss of 0.1 under room-dry conditions, 0.1 under drained conditions and 0.08 under undrained conditions. The shear stress decay was about 75 percent over the first 5 cm of slip, independently of the ambient conditions. However, at a given σneff, δ and V, steady state shear stress was 20 percent lower under undrained than under drained and room dry conditions. Moreover, Pf under undrained conditions increased with displacement following a power law. Conversely, Pf and σn did not vary under drained conditions. After all experiments, a continuous, 100-200 µm thick, layer of glass (Scanning Electron Microscope investigation) separated the rock cylinders, irrespective of the ambient and hydraulic conditions. In summary, the mechanical

  5. Intrapopulation Variability Shaping Isotope Discrimination and Turnover: Experimental Evidence in Arctic Foxes

    PubMed Central

    Lecomte, Nicolas; Ahlstrøm, Øystein; Ehrich, Dorothée; Fuglei, Eva; Ims, Rolf A.; Yoccoz, Nigel G.

    2011-01-01

    Background Tissue-specific stable isotope signatures can provide insights into the trophic ecology of consumers and their roles in food webs. Two parameters are central for making valid inferences based on stable isotopes, isotopic discrimination (difference in isotopic ratio between consumer and its diet) and turnover time (renewal process of molecules in a given tissue usually measured when half of the tissue composition has changed). We investigated simultaneously the effects of age, sex, and diet types on the variation of discrimination and half-life in nitrogen and carbon stable isotopes (δ15N and δ13C, respectively) in five tissues (blood cells, plasma, muscle, liver, nail, and hair) of a top predator, the arctic fox Vulpes lagopus. Methodology/Principal Findings We fed 40 farmed foxes (equal numbers of adults and yearlings of both sexes) with diet capturing the range of resources used by their wild counterparts. We found that, for a single species, six tissues, and three diet types, the range of discrimination values can be almost as large as what is known at the scale of the whole mammalian or avian class. Discrimination varied depending on sex, age, tissue, and diet types, ranging from 0.3‰ to 5.3‰ (mean  = 2.6‰) for δ15N and from 0.2‰ to 2.9‰ (mean  = 0.9‰) for δ13C. We also found an impact of population structure on δ15N half-life in blood cells. Varying across individuals, δ15N half-life in plasma (6 to 10 days) was also shorter than for δ13C (14 to 22 days), though δ15N and δ13C half-lives are usually considered as equal. Conclusion/Significance Overall, our multi-factorial experiment revealed that at least six levels of isotopic variations could co-occur in the same population. Our experimental analysis provides a framework for quantifying multiple sources of variation in isotopic discrimination and half-life that needs to be taken into account when designing and analysing ecological field studies. PMID:21731715

  6. The Effects of Prosocial Video Games on Prosocial Behaviors: International Evidence from Correlational, Longitudinal, and Experimental Studies

    PubMed Central

    Gentile, Douglas A.; Anderson, Craig A.; Yukawa, Shintaro; Ihori, Nobuko; Saleem, Muniba; Ming, Lim Kam; Shibuya, Akiko; Liau, Albert K.; Khoo, Angeline; Bushman, Brad J.; Huesmann, L. Rowell; Sakamoto, Akira

    2009-01-01

    Although dozens of studies have documented a relation between violent video games and aggressive behaviors, very little attention has been paid to potential effects of prosocial games. Theoretically, games in which game characters help and support each other in nonviolent ways should increase both short-term and long-term prosocial behaviors. We report three studies conducted in three countries with three age groups to test this hypothesis. In the correlational study, Singaporean middle-school students who played more prosocial games behaved more prosocially. In the two longitudinal samples of Japanese children and adolescents, prosocial game play predicted later increases in prosocial behavior. In the experimental study, U.S. undergraduates randomly assigned to play prosocial games behaved more prosocially toward another student. These similar results across different methodologies, ages, and cultures provide robust evidence a prosocial game content effect, and provide support for the General Learning Model. PMID:19321812

  7. The effects of prosocial video games on prosocial behaviors: international evidence from correlational, longitudinal, and experimental studies.

    PubMed

    Gentile, Douglas A; Anderson, Craig A; Yukawa, Shintaro; Ihori, Nobuko; Saleem, Muniba; Ming, Lim Kam; Shibuya, Akiko; Liau, Albert K; Khoo, Angeline; Bushman, Brad J; Rowell Huesmann, L; Sakamoto, Akira

    2009-06-01

    Although dozens of studies have documented a relationship between violent video games and aggressive behaviors, very little attention has been paid to potential effects of prosocial games. Theoretically, games in which game characters help and support each other in nonviolent ways should increase both short-term and long-term prosocial behaviors. We report three studies conducted in three countries with three age groups to test this hypothesis. In the correlational study, Singaporean middle-school students who played more prosocial games behaved more prosocially. In the two longitudinal samples of Japanese children and adolescents, prosocial game play predicted later increases in prosocial behavior. In the experimental study, U.S. undergraduates randomly assigned to play prosocial games behaved more prosocially toward another student. These similar results across different methodologies, ages, and cultures provide robust evidence of a prosocial game content effect, and they provide support for the General Learning Model. PMID:19321812

  8. 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

  9. Experimental evidence of a buoyant mass difference between bovine spermatozoa bearing X- and Y-chromosomes using a micromechanical resonator.

    PubMed

    Mauro, Marco; Battaglia, Raffaele; Ferrini, Gianluca; Puglisi, Roberto; Balduzzi, Donatella; Galli, Andrea

    2014-03-01

    Flow cytometry is to date the only commercially viable technique for sex preselection of mammalian spermatozoa, measuring the different DNA content in X- and Y-chromosome bearing spermatozoa. Here we present experimental evidence of a measurable difference between bovine spermatozoa bearing X- and Y-chromosomes based on their buoyant mass. Single cells of two populations of flow-cytometrically sorted spermatozoa were analyzed by means of a micromechanical resonator, consisting of a suspended doubly-clamped microcapillary. Spermatozoa buoyant mass is related to the transitory variation in vibration phase lag, caused by the passage through the sensitive area of a single sperm cell suspended in a fluid. Data analysis shows two well-separated distributions and provides evidence of the sensor capabilities to detect the buoyant mass of single cells with such accuracy to distinguish X- and Y-chromosome bearing spermatozoa. These preliminary results suggest the possibility to develop an intriguing technique alternative to flow cytometry in the field of sperm sorting. PMID:24419052

  10. 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. PMID:23289577

  11. Cash transfers, maternal depression and emotional well-being: Quasi-experimental evidence from India's Janani Suraksha Yojana programme.

    PubMed

    Powell-Jackson, Timothy; Pereira, Shreya K; Dutt, Varun; Tougher, Sarah; Haldar, Kaveri; Kumar, Paresh

    2016-08-01

    Maternal depression is an important public health concern. We investigated whether a national-scale initiative that provides cash transfers to women giving birth in government health facilities, the Janani Suraksha Yojana (JSY), reduced maternal depression in India's largest state, Uttar Pradesh. Using primary data on 1695 women collected in early 2015, our quasi-experimental design exploited the fact that some women did not receive the JSY cash due to administrative problems in its disbursement - reasons that are unlikely to be correlated with determinants of maternal depression. We found that receipt of the cash was associated with an 8.5% reduction in the continuous measure of maternal depression and a 36% reduction in moderate depression. There was no evidence of an association with measures of emotional well-being, namely happiness and worry. The results suggest that the JSY had a clinically meaningful effect in reducing the burden of maternal depression, possibly by lessening the financial strain of delivery care. They contribute to the evidence that financial incentive schemes may have public health benefits beyond improving uptake of targeted health services. PMID:27387651

  12. Argon, oxygen, and boron isotopic evidence documenting 40ArE accumulation in phengite during water-rich high-pressure subduction metasomatism of continental crust

    NASA Astrophysics Data System (ADS)

    Menold, Carrie A.; Grove, Marty; Sievers, Natalie E.; Manning, Craig E.; Yin, An; Young, Edward D.; Ziegler, Karen

    2016-07-01

    were even older, exceeding the time of eclogite formation by a factor of 1.7. In contrast, lower pressure retrograde muscovite present within the host gneiss and in discrete shear zones cutting the selvage yield 40Ar/39Ar ages that were younger than the time of HP metamorphism and consistent with regional cooling age patterns. Our observation of high 40ArE concentrations in phengite from schistose rocks infiltrated by regionally extensive fluids at HP conditions runs contrary to widely held expectations. Conventional wisdom dictates that low phengite/fluid partition coefficients for argon (Dphg/fluid Ar =10-3to10-5) coupled with the dry, closed systems conditions that are widely reported to characterize HP metamorphism of continental crust explains why high concentrations of 40ArE partitions are able to accumulate within phengite. We alternatively propose that phengite/fluid partition coefficients for argon increase linearly with pressure to values as high as 10-2 to allow phengites to accumulate large amounts of 40ArE from aqueous fluids under HP to UHP conditions.

  13. Proprotein convertase subtilisin kexin type 9 and high-density lipoprotein metabolism: experimental animal models and clinical evidence.

    PubMed

    Ferri, Nicola; Corsini, Alberto; Macchi, Chiara; Magni, Paolo; Ruscica, Massimiliano

    2016-07-01

    Proprotein convertase subtilisin kexin type 9 (PCSK9) belongs to the proprotein convertase family. Several studies have demonstrated its involvement in the regulation of low-density lipoprotein (LDL) cholesterol levels by inducing the degradation of the LDL receptor (LDLR). However, experimental, epidemiologic, and pharmacologic data provide important evidence on the role of PCSK9 also on high-density lipoproteins (HDLs). In mice, PCSK9 regulates the HDL cholesterol (HDL-C) levels by the degradation of hepatic LDLR, thus inhibiting the uptake of apolipoprotein (Apo)E-containing HDLs. Several epidemiologic and genetic studies reported positive relationship between PCSK9 and HDL-C levels, likely by reducing the uptake of the ApoE-containing HDL particles. PCSK9 enhances also the degradation of LDLR's closest family members, ApoE receptor 2, very low-density lipoprotein receptor, and LDLR-related protein 1. This feature provides a molecular mechanism by which PCSK9 may affect HDL metabolism. Experimental studies demonstrated that PCSK9 directly interacts with HDL by modulating PCSK9 self-assembly and its binding to the LDLR. Finally, the inhibition of PCSK9 by means of monoclonal antibodies directed to PCSK9 (ie, evolocumab and alirocumab) determines an increase of HDL-C fraction by 7% and 4.2%, respectively. Thus, the understanding of the role of PCSK9 on HDL metabolism needs to be elucidated with a particular focus on the effect of PCSK9 on HDL-mediated reverse cholesterol transport. PMID:26548330

  14. Experimental evidence and 43 years of monitoring data show that food limits reproduction in a food-caching passerine.

    PubMed

    Derbyshire, Rachael; Strickland, Dan; Norris, D Ryan

    2015-11-01

    Several species of birds and mammals overcome periods of scarcity by caching food, but for the vast majority of species, it is virtually unknown whether they are food limited during these periods. The Gray Jay (Perisoreus canadensis) is a boreal-resident, food-caching passerine that breeds in late winter when fresh food is scarce. Using a two-year experiment and 43 years of monitoring data, we examined the food limitation hypothesis in a population of Gray Jays in Algonquin Park, Ontario, Canada, that has declined by over 50% in the last three decades. Breeding pairs that were experimentally food supplemented during the pre-breeding period laid eggs earlier in the season and had larger brood sizes than non-supplemented controls. From the long-term data, we found strong evidence that pairs that were regularly supplemented by the public (park visitors) tended to lay eggs earlier and have larger clutches and brood sizes compared to pairs that were not supplemented. Nestling body condition (mass controlled for body size) was not influenced by either experimental or public food supplementation. Our results support the hypothesis that Gray Jays are food limited during their late-winter breeding period and suggest that warmer fall temperatures, which have been hypothesized to lead to cache spoilage, may have a significant impact on reproductive success in this declining population. Moreover, our results contribute to understanding how public feeding can influence the fitness of wild animals. PMID:27070019

  15. Direct, experimental evidence of the Fermi surface in YBa sub 2 Cu sub 3 O sub 7-x

    SciTech Connect

    Haghighi, H.; Kaiser, J.H.; Rayner, S.L.; West, R.N. ); Liu, J.Z.; Shelton, R. ); Howell, R.H.; Sterne, P.A.; Solal, F.; Fluss, M.J. )

    1991-04-29

    We report new measurements of the electron-positron momentum spectra of YBa{sub 2}Cu{sub 3}O{sub 7-x} performed with ultra-high statistical precision. These data differ from previous results in two significant respects: They show the D{sub 2} symmetry appropriate for untwinned crystals and, more importantly, they show unmistakable, statistically significant, discontinuities that are evidence of a major Fermi surface section. These results provide a partial answer to a question of special significance to the study of high temperature superconductors i.e. the distribution of the electrons in the material, the electronic structure. Special consideration has been given both experimentally and theoretically to the existence and shape of a Fermi surface in the materials and to the superconducting gap. There are only three experimental techniques that can provide details of the electronic structure at useful resolutions. They are angular correlation of positron annihilation radiation, ACAR, angle resolved photo emission, PE, and de Haas van Alphen measurements. 11 refs., 4 figs.

  16. Evidence for early intracellular accumulation of volatile compounds during spadix development in Arum italicum L. and preliminary data on some tropical Aroids

    NASA Astrophysics Data System (ADS)

    Leguet, Aurélia; Gibernau, Marc; Shintu, Laetitia; Caldarelli, Stefano; Moja, Sandrine; Baudino, Sylvie; Caissard, Jean-Claude

    2014-08-01

    Staining and histochemistry of volatile organic compounds (VOCs) were performed at different inflorescence developmental stages on nine aroid species; one temperate, Arum italicum and eight tropical from the genera Caladium, Dieffenbachia and Philodendron. Moreover, a qualitative and quantitative analysis of VOCs constituting the scent of A. italicum, depending on the stage of development of inflorescences was also conducted. In all nine species, vesicles were observed in the conical cells of either the appendix or the stamens (thecae) and the staminodes. VOCs were localised in intracellular vesicles from the early stages of inflorescence development until their release during receptivity of gynoecium. This localisation was observed by the increase of both number and diameter of the vesicles during 1 week before receptivity. Afterwards, vesicles were fewer and smaller but rarely absent. In A. italicum, staining and gas chromatography analyses confirmed that the vesicles contained terpenes. The quantitatively most important ones were the sesquiterpenes, but monoterpenes were not negligible. Indeed, the quantities of terpenes matched the vesicles' size evolution during 1 week. Furthermore, VOCs from different biosynthetic pathways (sesquiterpenes and alkanes) were at their maximum quantity 2 days before gynoecium receptivity (sesquiterpenes and alkanes) or during receptivity (isobutylamine, monoterpenes, skatole and p-cresol). VOCs seemed to be emitted during gynoecium receptivity and/or during thermogenesis, and FADs are accumulated after thermogenesis in the spadix. These complex dynamics of the different VOCs could indicate specialisation of some VOCs and cell machinery to attract pollinators on the one hand and to repulse/protect against phytophagous organisms and pathogens after pollination on the other hand.

  17. Evidence for early intracellular accumulation of volatile compounds during spadix development in Arum italicum L. and preliminary data on some tropical Aroids.

    PubMed

    Leguet, Aurélia; Gibernau, Marc; Shintu, Laetitia; Caldarelli, Stefano; Moja, Sandrine; Baudino, Sylvie; Caissard, Jean-Claude

    2014-08-01

    Staining and histochemistry of volatile organic compounds (VOCs) were performed at different inflorescence developmental stages on nine aroid species; one temperate, Arum italicum and eight tropical from the genera Caladium, Dieffenbachia and Philodendron. Moreover, a qualitative and quantitative analysis of VOCs constituting the scent of A. italicum, depending on the stage of development of inflorescences was also conducted. In all nine species, vesicles were observed in the conical cells of either the appendix or the stamens (thecae) and the staminodes. VOCs were localised in intracellular vesicles from the early stages of inflorescence development until their release during receptivity of gynoecium. This localisation was observed by the increase of both number and diameter of the vesicles during 1 week before receptivity. Afterwards, vesicles were fewer and smaller but rarely absent. In A. italicum, staining and gas chromatography analyses confirmed that the vesicles contained terpenes. The quantitatively most important ones were the sesquiterpenes, but monoterpenes were not negligible. Indeed, the quantities of terpenes matched the vesicles' size evolution during 1 week. Furthermore, VOCs from different biosynthetic pathways (sesquiterpenes and alkanes) were at their maximum quantity 2 days before gynoecium receptivity (sesquiterpenes and alkanes) or during receptivity (isobutylamine, monoterpenes, skatole and p-cresol). VOCs seemed to be emitted during gynoecium receptivity and/or during thermogenesis, and FADs are accumulated after thermogenesis in the spadix. These complex dynamics of the different VOCs could indicate specialisation of some VOCs and cell machinery to attract pollinators on the one hand and to repulse/protect against phytophagous organisms and pathogens after pollination on the other hand. PMID:24925357

  18. In vivo stimulation of connective tissue accumulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ in rat experimental wounds.

    PubMed

    Maquart, F X; Bellon, G; Chaqour, B; Wegrowski, J; Patt, L M; Trachy, R E; Monboisse, J C; Chastang, F; Birembaut, P; Gillery, P

    1993-11-01

    The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ (GHK-Cu) was first described as a growth factor for differentiated cells. Recent in vitro data showed that it possesses several properties of a potential activator of wound repair. We investigated the effects of GHK-Cu in vivo, using the wound chamber model described previously (Schilling, J.A., W. Joel, and M.T. Shurley, 1959. Surgery [St. Louis]. 46:702-710). Stainless steel wire mesh cylinders were implanted subcutaneously on the back of rats. The animals were divided into groups that received sequential injections into the wound chamber of either saline (control group) or various concentrations of GHK-Cu. At the end of the experiments, rats were killed, wound chambers were collected, and their content was analyzed for dry weight, total proteins, collagen, DNA, elastin, glycosaminoglycans, and specific mRNAs for collagens and TGF beta. In the GHK-Cu-injected wound chambers, a concentration-dependent increase of dry weight, DNA, total protein, collagen, and glycosaminoglycan contents was found. The stimulation of collagen synthesis was twice that of noncollagen proteins. Type I and type III collagen mRNAs were increased but not TGF beta mRNAs. An increase of the relative amount of dermatan sulfate was also found. A control tripeptide, L-glutamyl-L-histidyl-L-proline, had no significant effect. These results demonstrate that GHK-Cu is able to increase extracellular matrix accumulation in wounds in vivo. PMID:8227353

  19. In vivo stimulation of connective tissue accumulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ in rat experimental wounds.

    PubMed Central

    Maquart, F X; Bellon, G; Chaqour, B; Wegrowski, J; Patt, L M; Trachy, R E; Monboisse, J C; Chastang, F; Birembaut, P; Gillery, P

    1993-01-01

    The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ (GHK-Cu) was first described as a growth factor for differentiated cells. Recent in vitro data showed that it possesses several properties of a potential activator of wound repair. We investigated the effects of GHK-Cu in vivo, using the wound chamber model described previously (Schilling, J.A., W. Joel, and M.T. Shurley, 1959. Surgery [St. Louis]. 46:702-710). Stainless steel wire mesh cylinders were implanted subcutaneously on the back of rats. The animals were divided into groups that received sequential injections into the wound chamber of either saline (control group) or various concentrations of GHK-Cu. At the end of the experiments, rats were killed, wound chambers were collected, and their content was analyzed for dry weight, total proteins, collagen, DNA, elastin, glycosaminoglycans, and specific mRNAs for collagens and TGF beta. In the GHK-Cu-injected wound chambers, a concentration-dependent increase of dry weight, DNA, total protein, collagen, and glycosaminoglycan contents was found. The stimulation of collagen synthesis was twice that of noncollagen proteins. Type I and type III collagen mRNAs were increased but not TGF beta mRNAs. An increase of the relative amount of dermatan sulfate was also found. A control tripeptide, L-glutamyl-L-histidyl-L-proline, had no significant effect. These results demonstrate that GHK-Cu is able to increase extracellular matrix accumulation in wounds in vivo. Images PMID:8227353

  20. Role of taurine accumulation in keratinocyte hydration.

    PubMed

    Janeke, Guido; Siefken, Wilfried; Carstensen, Stefanie; Springmann, Gunja; Bleck, Oliver; Steinhart, Hans; Höger, Peter; Wittern, Klaus-Peter; Wenck, Horst; Stäb, Franz; Sauermann, Gerhard; Schreiner, Volker; Doering, Thomas

    2003-08-01

    Epidermal keratinocytes are exposed to a low water concentration at the stratum corneum-stratum granulosum interface. When epithelial tissues are osmotically perturbed, cellular protection and cell volume regulation is mediated by accumulation of organic osmolytes such as taurine. Previous studies reported the presence of taurine in the epidermis of several animal species. Therefore, we analyzed human skin for the presence of the taurine transporter (TAUT) and studied the accumulation of taurine as one potential mechanism protecting epidermal keratinocytes from dehydration. According to our results, TAUT is expressed as a 69 kDa protein in human epidermis but not in the dermis. For the epidermis a gradient was evident with maximal levels of TAUT in the outermost granular keratinocyte layer and lower levels in the stratum spinosum. No TAUT was found in the basal layer or in the stratum corneum. Keratinocyte accumulation of taurine was induced by experimental induction of skin dryness via application of silica gel to human skin. Cultured human keratinocytes accumulated taurine in a concentration- and osmolarity-dependent manner. TAUT mRNA levels were increased after exposure of human keratinocytes to hyperosmotic culture medium, indicating osmosensitive TAUT mRNA expression as part of the adaptation of keratinocytes to hyperosmotic stress. Keratinocyte uptake of taurine was inhibited by beta-alanine but not by other osmolytes such as betaine, inositol, or sorbitol. Accumulation of taurine protected cultured human keratinocytes from both osmotically induced and ultraviolet-induced apoptosis. Our data indicate that taurine is an important epidermal osmolyte required to maintain keratinocyte hydration in a dry environment. PMID:12880428

  1. The RAMESSES experiment-II. Evidence for accumulated melt beneath a slow spreading ridge from wide-angle refraction and multichannel reflection seismic profiles

    NASA Astrophysics Data System (ADS)

    Navin, D. A.; Peirce, C.; Sinha, M. C.

    1998-12-01

    The RAMESSES study (Reykjanes Axial Melt Experiment: Structural Synthesis from Electromagnetics and Seismics) targeted an apparently magmatically active axial volcanic ridge (AVR), centred on 57°45'N at the Reykjanes Ridge, with the aim of investigating the processes of crustal accretion at a slow spreading mid-ocean ridge. As part of this multicomponent experiment, airgun and explosive wide-angle seismic data were recorded by 10 digital ocean-bottom seismometers (OBSs) along profiles oriented both across- and along-axis. Coincident normal-incidence seismic, bathymetry and underway gravity and magnetic data were also collected. Forward modelling of the seismic and gravity data has revealed layer thicknesses, velocities and densities similar to those observed elsewhere within the oceanic crust near mid-ocean ridges. At 57°45'N, the Reykjanes Ridge has a crustal thickness of approximately 7.5 km on-axis. However, the crust is modelled to decrease in thickness slightly off-axis (i.e. with age), which implies that full crustal thickness is achieved on-axis and that it is subsequently thinned, most likely, by off-axis extension. Modelling also indicates that the AVR is underlain by a thin (~100 m), narrow (~4 km) melt lens some 2.5 km beneath the seafloor, which overlies a broader zone of partial melt approximately 8 km in width. Thus the results of this study provide the first clear evidence for a crustal magma chamber beneath any slow spreading ridge. The size and depth of this magma chamber (the melt lens and underlying zone of partial melt) are similar to those observed beneath fast and intermediate spreading ridges, which implies that the processes of crustal accretion are similar at all spreading rates. Hence the lack of previous observations of magma chambers beneath slow spreading ridges is probably temporally related to the periods of magmatic activity being considerably shorter and more widely spaced in time than at fast and intermediate spreading ridges.

  2. A Single B-repeat of Staphylococcus epidermidis accumulation-associated protein induces protective immune responses in an experimental biomaterial-associated infection mouse model.

    PubMed

    Yan, Lin; Zhang, Lei; Ma, Hongyan; Chiu, David; Bryers, James D

    2014-09-01

    Nosocomial infections are the fourth leading cause of morbidity and mortality in the United States, resulting in 2 million infections and ∼100,000 deaths each year. More than 60% of these infections are associated with some type of biomedical device. Staphylococcus epidermidis is a commensal bacterium of the human skin and is the most common nosocomial pathogen infecting implanted medical devices, especially those in the cardiovasculature. S. epidermidis antibiotic resistance and biofilm formation on inert surfaces make these infections hard to treat. Accumulation-associated protein (Aap), a cell wall-anchored protein of S. epidermidis, is considered one of the most important proteins involved in the formation of S. epidermidis biofilm. A small recombinant protein vaccine comprising a single B-repeat domain (Brpt1.0) of S. epidermidis RP62A Aap was developed, and the vaccine's efficacy was evaluated in vitro with a biofilm inhibition assay and in vivo in a murine model of biomaterial-associated infection. A high IgG antibody response against S. epidermidis RP62A was detected in the sera of the mice after two subcutaneous immunizations with Brpt1.0 coadministered with Freund's adjuvant. Sera from Brpt1.0-immunized mice inhibited in vitro S. epidermidis RP62A biofilm formation in a dose-dependent pattern. After receiving two immunizations, each mouse was surgically implanted with a porous scaffold disk containing 5 × 10(6) CFU of S. epidermidis RP62A. Weight changes, inflammatory markers, and histological assay results after challenge with S. epidermidis indicated that the mice immunized with Brpt1.0 exhibited significantly higher resistance to S. epidermidis RP62A implant infection than the control mice. Day 8 postchallenge, there was a significantly lower number of bacteria in scaffold sections and surrounding tissues and a lower residual inflammatory response to the infected scaffold disks for the Brpt1.0-immunized mice than for of the ovalbumin (Ova

  3. OA01.25.The first direct experimental evidence correlating ayurveda based tridosha prakriti, with western constitutional psychology somatotypes

    PubMed Central

    Metri, Kashinath G; Bhargav, Hemant; Ramarao, Nagendra Hongasandra; Rizzo-Sierra; Basavakatti, Ramakrishna R

    2012-01-01

    Purpose: Ayurveda is one of the most ancient systems of medical health care. The basic principles, diagnosis of the diseases and their treatment are based on individual prakriti (constitutional type). Ayurveda further classifies the prakriti of an individual on the basis of a set of psychosomatic attributes of personality, depending on whether this individual belongs to Vata, Pitta, or Kapha prakriti, or any combination of them (Patwardhan et al., 2005). The appropriate prakriti assessment is done by several means including questionnaires (Rastogi, 2012; Shilpa and Venkatesha-Murthy, 2011). We aimed to obtain experimental evidence correlating Ayurveda based tridosha-prakriti with western constitutional psychology somatotypes (Rizzo-Sierra, 2011). Method: We employed our Tridosha-prakriti questionnaire (Ramakrishna and Nagendra, 2012), and compared its results with a set of body composition parameters: Height, body weight, body mass index (BMI), muscle mass, fat mass, and fat percentage in normal healthy volunteers (25 males and 25 females, mean age was 26 (± 4) and 25 (± 6) years respectively). Moreover, two-tailed Pearson's correlations were investigated to match the extreme prakriti types with the western constitutional psychology somatotypes, through the mentioned body composition measures. Result: Significant negative correlations were observed between the percentage of Vata attributes as per the questionnaire in the individuals and their BMI, body weight and fat mass respectively (p<0.05). Similarly, there was a significant positive correlation between the percentage of Pitta attributes with the height, body weight, and muscle mass respectively. Also, a significant positive correlation was observed between the percentage of Kapha attributes with fat mass and fat percentage, along with a negative correlation with height. Conclusion: We provide evidence-linking Ayurveda to modern constitutional psychology. In this way, a concept such as prakriti is suggested

  4. Experimental evidence of the tonic vibration reflex during whole-body vibration of the loaded and unloaded leg.

    PubMed

    Zaidell, Lisa N; Mileva, Katya N; Sumners, David P; Bowtell, Joanna L

    2013-01-01

    Increased muscle activation during whole-body vibration (WBV) is mainly ascribed to a complex spinal and supraspinal neurophysiological mechanism termed the tonic vibration reflex (TVR). However, TVR has not been experimentally demonstrated during low-frequency WBV, therefore this investigation aimed to determine the expression of TVR during WBV. Whilst seated, eight healthy males were exposed to either vertical WBV applied to the leg via the plantar-surface of the foot, or Achilles tendon vibration (ATV) at 25 Hz and 50 Hz for 70s. Ankle plantar-flexion force, tri-axial accelerations at the shank and vibration source, and surface EMG activity of m. soleus (SOL) and m. tibialis anterior (TA) were recorded from the unloaded and passively loaded leg to simulate body mass supported during standing. Plantar flexion force was similarly augmented by WBV and ATV and increased over time in a load- and frequency dependent fashion. SOL and TA EMG amplitudes increased over time in all conditions independently of vibration mode. 50 Hz WBV and ATV resulted in greater muscle activation than 25 Hz in SOL when the shank was loaded and in TA when the shank was unloaded despite the greater transmission of vertical acceleration from source to shank with 25 Hz and WBV, especially during loading. Low-amplitude WBV of the unloaded and passively loaded leg produced slow tonic muscle contraction and plantar-flexion force increase of similar magnitudes to those induced by Achilles tendon vibration at the same frequencies. This study provides the first experimental evidence supporting the TVR as a plausible mechanism underlying the neuromuscular response to whole-body vibration. PMID:24386466

  5. Experimental inoculation of Artibeus jamaicensis bats with dengue virus serotypes 1 or 4 showed no evidence of sustained replication.

    PubMed

    Cabrera-Romo, Salomé; Recio-Tótoro, Benito; Alcalá, Ana C; Lanz, Humberto; del Ángel, Rosa María; Sánchez-Cordero, Victor; Rodríguez-Moreno, Ángel; Ludert, Juan E

    2014-12-01

    Dengue is the most important mosquito-borne viral disease to humans. Bats are potential reservoirs for flaviviruses, including dengue virus (DENV). In this work, Artibeus jamaicensis bats were inoculated with two serotypes of DENV using different routes. For experimental inoculations (EI) 1 and 2, bats were inoculated subcutaneously or intraperitoneally with DENV-4; for EI-3 bats were inoculated intraperitoneally with DENV-1. Mock inoculated bats were kept as controls. In EI-4, bats were bitten by Aedes aegypti mosquitoes infected with DENV-1 or 4. Reverse transcription-polymerase chain reaction assays in plasma and spleen tissue collected from Day 1 to Days 9-17 after inoculation failed to reveal the presence of viral RNA in any of the samples. No evidence of circulating NS1 or specific anti-DENV IgG was detected in the plasma of the inoculated bats. These results indicate that A. jamaicensis bats are incapable of sustaining dengue virus replication and are unlikely to act as reservoirs for this virus. PMID:25311698

  6. Probing Bis-Fe(IV) MauG: Experimental Evidence for the Long-Range Charge-Resonance Model

    PubMed Central

    Geng, Jiafeng; Davis, Ian

    2015-01-01

    The biosynthesis of tryptophan tryptophylquinone, a protein-derived cofactor, involves a long-range reaction mediated by a bis-Fe(IV) intermediate of a di-heme enzyme, MauG. Recently, a unique charge-resonance (CR) phenomenon was discovered in this intermediate, and a biological, long-distance CR model was proposed. This model suggests that the chemical nature of the bis-Fe(IV) species is not as simple as it appears; rather, it is composed of a collection of resonance structures in a dynamic equilibrium. Here, we experimentally evaluated the proposed CR model by introducing small molecules to, and measuring the temperature dependence of, bis-Fe(IV) MauG. Spectroscopic evidence was presented to demonstrate that the selected compounds increase the decay rate of the bis-Fe(IV) species via disrupting the equilibrium of the resonance structures that constitutes the proposed CR model. The results support this new CR model and bring a fresh concept to the classical CR theory. PMID:25631460

  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. Experimental evidence for the formation of CoFe{sub 2}C phase with colossal magnetocrystalline-anisotropy

    SciTech Connect

    El-Gendy, Ahmed A. E-mail: ecarpenter2@vcu.edu; Bertino, Massimo; Qian, Meichun; Khanna, Shiv N. E-mail: ecarpenter2@vcu.edu; Clifford, Dustin; Carpenter, Everett E. E-mail: ecarpenter2@vcu.edu

    2015-05-25

    Attainment of magnetic order in nanoparticles at room temperature is an issue of critical importance for many different technologies. For ordinary ferromagnetic materials, a reduction in size leads to decreased magnetic anisotropy and results in superparamagnetic relaxations. If, instead, anisotropy could be enhanced at reduced particle sizes, then it would be possible to attain stable magnetic order at room temperature. Herein, we provide experimental evidence substantiating the synthesis of a cobalt iron carbide phase (CoFe{sub 2}C) of nanoparticles. Structural characterization of the CoFe{sub 2}C carbide phase was performed by transmission electron microscopy, electron diffraction and energy electron spectroscopy. X-ray diffraction was also performed as a complimentary analysis. Magnetic characterization of the carbide phase revealed a blocking temperature, T{sub B}, of 790 K for particles with a domain size as small as 5 ± 1 nm. The particles have magnetocrystalline anisotropy of 4.6 ± 2 × 10{sup 6 }J/m{sup 3}, which is ten times larger than that of Co nanoparticles. Such colossal anisotropy leads to thermally stable long range magnetic order. Moreover, the thermal stability constant is much larger than that of the commonly used FePt nanoparticles. With thermal stability and colossal anisotropy, the CoFe{sub 2}C nanoparticles have huge potential for enhanced magnetic data storage devices.

  9. Experimental evidence for the formation of CoFe2C phase with colossal magnetocrystalline-anisotropy

    SciTech Connect

    El-Gendy, AA; Bertino, M; Clifford, D; Qian, MC; Khanna, SN; Carpenter, EE

    2015-05-25

    Attainment of magnetic order in nanoparticles at room temperature is an issue of critical importance for many different technologies. For ordinary ferromagnetic materials, a reduction in size leads to decreased magnetic anisotropy and results in superparamagnetic relaxations. If, instead, anisotropy could be enhanced at reduced particle sizes, then it would be possible to attain stable magnetic order at room temperature. Herein, we provide experimental evidence substantiating the synthesis of a cobalt iron carbide phase (CoFe2C) of nanoparticles. Structural characterization of the CoFe2C carbide phase was performed by transmission electron microscopy, electron diffraction and energy electron spectroscopy. X-ray diffraction was also performed as a complimentary analysis. Magnetic characterization of the carbide phase revealed a blocking temperature, TB, of 790K for particles with a domain size as small as 5 +/- 1 nm. The particles have magnetocrystalline anisotropy of 4.662 +/- 10 6 J/m(3), which is ten times larger than that of Co nanoparticles. Such colossal anisotropy leads to thermally stable long range magnetic order. Moreover, the thermal stability constant is much larger than that of the commonly used FePt nanoparticles. With thermal stability and colossal anisotropy, the CoFe2C nanoparticles have huge potential for enhanced magnetic data storage devices. (C) 2015 AIP Publishing LLC.

  10. Experimental Inoculation of Artibeus jamaicensis Bats with Dengue Virus Serotypes 1 or 4 Showed No Evidence of Sustained Replication

    PubMed Central

    Cabrera-Romo, Salomé; Recio-Tótoro, Benito; Alcalá, Ana C.; Lanz, Humberto; del Ángel, Rosa María; Sánchez-Cordero, Victor; Rodríguez-Moreno, Ángel; Ludert, Juan E.

    2014-01-01

    Dengue is the most important mosquito-borne viral disease to humans. Bats are potential reservoirs for flaviviruses, including dengue virus (DENV). In this work, Artibeus jamaicensis bats were inoculated with two serotypes of DENV using different routes. For experimental inoculations (EI) 1 and 2, bats were inoculated subcutaneously or intraperitoneally with DENV-4; for EI-3 bats were inoculated intraperitoneally with DENV-1. Mock inoculated bats were kept as controls. In EI-4, bats were bitten by Aedes aegypti mosquitoes infected with DENV-1 or 4. Reverse transcription-polymerase chain reaction assays in plasma and spleen tissue collected from Day 1 to Days 9–17 after inoculation failed to reveal the presence of viral RNA in any of the samples. No evidence of circulating NS1 or specific anti-DENV IgG was detected in the plasma of the inoculated bats. These results indicate that A. jamaicensis bats are incapable of sustaining dengue virus replication and are unlikely to act as reservoirs for this virus. PMID:25311698

  11. A Direct Experimental Evidence For the New Thermodynamic Boundary in the Supercritical State: Implications for Earth and Planetary Sciences.

    NASA Astrophysics Data System (ADS)

    Bolmatov, D.

    2015-12-01

    While scientists have a good theoretical understanding of the heat capacity of both solids and gases, a general theory of the heat capacity of liquids has always remained elusive. Apart from being an awkward hole in our knowledge, heat capacity - the amount of heat needed to change a substance's temperature by a certain amount - is a relevant quantity that it would be nice to be able to predict. I will introduce a phonon-based approach to liquids and supercritical fluids to describe its thermodynamics in terms of sound propagation. I will show that the internal liquid energy has a transverse sound propagation gaps and explain their evolution with temperature variations on the P-T diagram. I will explain how this theoretical framework covers the Debye theory of solids, the phonon theory of liquids, and thermodynamic limits such as the Delong-Petit and the ideal gas thermodynamic limits. As a results, the experimental evidence for the new thermodynamic boundary in the supercritical state (the Frenkel line) on the P-T phase diagram will be demonstrated. Then, I will report on inelastic X-ray scattering experiments combined with the molecular dynamics simulations on deeply supercritical Ar. The presented results unveil the mechanism and regimes of sound propagation in the liquid matter and provide compelling evidence for the adiabatic-to-isothermal longitudinal sound propagation transition. As a result, a universal link will be demonstrated between the positive sound dispersion (PSD) phenomenon and the origin of transverse sound propagation revealing the viscous-to-elastic crossover in compressed liquids. Both can be considered as a universal fingerprint of the dynamic response of a liquid. They can be used then for a signal detection and analysis of a dynamic response in deep water and other fluids which is relevant for describing the thermodynamics of gas giants. The consequences of this finding will be discussed, including a physically justified way to demarcate the

  12. Experimental evidence of cut-wire-induced enhanced transmission of transverse-electric fields through sub-wavelength slits in a thin metallic screen

    NASA Astrophysics Data System (ADS)

    di Gennaro, Emiliano; Gallina, Ilaria; Andreone, Antonello; Castaldi, Giuseppe; Galdi, Vincenzo

    2010-12-01

    Recent numerical studies have demonstrated the possibility of achieving substantial enhancements in the transmission of transverse-electric-polarized electromagnetic fields through subwavelength slits in a thin metallic screen by placing single or paired metallic cut-wire arrays at a close distance from the screen. In this Letter, we report on the first experimental evidence of such extraordinary transmission phenomena, via microwave (X/Ku-band) measurements on printed-circuit-board prototypes. Experimental results agree very well with full-wave numerical predictions, and indicate an intrinsic robustness of the enhanced transmission phenomena with respect to fabrication tolerances and experimental imperfections.

  13. Relative importance of temperature and other factors in determining geographic boundaries of seaweeds: Experimental and phenological evidence

    NASA Astrophysics Data System (ADS)

    Breeman, A. M.

    1988-06-01

    Experimentally determined ranges of thermal tolerance and requirements for completion of the life history of some 60 seaweed species from the North Atlantic Ocean were compared with annual temperature regimes at their geographic boundaries. In all but a few species, thermal responses accounted for the location of boundaries. Distribution was restricted by: (a) lethal effects of high or low temperatures preventing survival of the hardiest life history stage (often microthalli), (b) temperature requirements for completion of the life history operating on any one process (i.e. [sexual] reproduction, formation of macrothalli or blades), (c) temperature requirements for the increase of population size (through growth or the formation of asexual propagules). Optimum growth/reproduction temperatures or lethal limits of the non-hardiest stage (often macrothalli) were irrelevant in explaining distribution. In some species, ecotypic differentiation in thermal responses over the distribution range influenced the location of geographic boundaries, but in many other species no such ecotypic differences were evident. Specific daylength requirements affected the location of boundaries only when interacting with temperature. The following types of thermal responses could be recognised, resulting in characteristic distribution patterns: (A) Species endemic to the (warm) temperate eastern Atlantic had narrow survival ranges (between ca 5 and ca 25°C) preventing occurrence in NE America. In species with isomorphic life histories without very specific temperature requirements for reproduction, northern and southern boundaries in Eur/Africa are set by lethal limits. Species with heteromorphic life histories often required high and/or low temperatures to induce reproduction in one or both life history phases which further restricted distribution. (B) Species endemic to the tropical western Atlantic also had narrow survival ranges (between ca 10 and ca 35°C). Northern boundaries are

  14. 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

  15. Diverse convergent evidence in the genetic analysis of complex disease: coordinating omic, informatic, and experimental evidence to better identify and validate risk factors.

    PubMed

    Ciesielski, Timothy H; Pendergrass, Sarah A; White, Marquitta J; Kodaman, Nuri; Sobota, Rafal S; Huang, Minjun; Bartlett, Jacquelaine; Li, Jing; Pan, Qinxin; Gui, Jiang; Selleck, Scott B; Amos, Christopher I; Ritchie, Marylyn D; Moore, Jason H; Williams, Scott M

    2014-01-01

    In omic research, such as genome wide association studies, researchers seek to repeat their results in other datasets to reduce false positive findings and thus provide evidence for the existence of true associations. Unfortunately this standard validation approach cannot completely eliminate false positive conclusions, and it can also mask many true associations that might otherwise advance our understanding of pathology. These issues beg the question: How can we increase the amount of knowledge gained from high throughput genetic data? To address this challenge, we present an approach that complements standard statistical validation methods by drawing attention to both potential false negative and false positive conclusions, as well as providing broad information for directing future research. The Diverse Convergent Evidence approach (DiCE) we propose integrates information from multiple sources (omics, informatics, and laboratory experiments) to estimate the strength of the available corroborating evidence supporting a given association. This process is designed to yield an evidence metric that has utility when etiologic heterogeneity, variable risk factor frequencies, and a variety of observational data imperfections might lead to false conclusions. We provide proof of principle examples in which DiCE identified strong evidence for associations that have established biological importance, when standard validation methods alone did not provide support. If used as an adjunct to standard validation methods this approach can leverage multiple distinct data types to improve genetic risk factor discovery/validation, promote effective science communication, and guide future research directions. PMID:25071867

  16. Nutrition, weight gain, and eating behavior in pregnancy: a review of experimental evidence for long-term effects on the risk of obesity in offspring

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Obesity has reached near epidemic proportions in the developed world. As reproductive age women are a part of this trend, the effect of maternal obesity on the developing fetus must be investigated. In this review, we evaluated the experimental evidence relating maternal nutritional status and eat...

  17. Experimental evidence of direct contact formation for the current transport in silver thick film metallized silicon emitters

    NASA Astrophysics Data System (ADS)

    Cabrera, Enrique; Olibet, Sara; Glatz-Reichenbach, Joachim; Kopecek, Radovan; Reinke, Daniel; Schubert, Gunnar

    2011-12-01

    Great advances have been achieved in the development of silver pastes. The use of smaller silver particles, higher silver content, and, thus, less glass frit allow modern silver pastes to contact high resistive emitters without the necessity of a selective emitter or subsequent plating. To identify the microscopic key reasons behind the improvement of silver paste, it is essential to understand the current transport mechanism from the silicon emitter into the bulk of the silver finger. Two current transport theories predominate: i) The current flows through the Ag crystallites grown into the Si emitter, which are separated by a thin glass layer or possibly in direct contact with the silver finger. ii) The current is transported by means of multistep tunneling into the silver finger across nano-Ag colloids in the glass layer, which are formed at optimal firing conditions; the formation of Ag crystallites into the Si surface is synonymous with over-firing. In this study, we contact Si solar cell emitters with different silver pastes on textured and flat silicon surfaces. A sequential selective silver-glass etching process is employed to expose and isolate the different contact components for current transport. The surface configurations after the etching sequences are observed with scanning electron microscopy. Liquid conductive silver is then applied to each sample and the contact resistivity is measured to determine the dominant microscopic conduction path system. We observe glass-free emitter areas at the tops of the pyramidal-textured Si that lead to the formation of direct contacts between the Ag crystallites grown into the Si emitter and the bulk of the silver finger. We present experimental evidence that the major current flow into the silver finger is through these direct contacts.

  18. Allogeneic bone marrow transplantation in models of experimental autoimmune encephalomyelitis: evidence for a graft-versus-autoimmunity effect.

    PubMed

    Van Wijmeersch, Bart; Sprangers, Ben; Rutgeerts, Omer; Lenaerts, Caroline; Landuyt, Willy; Waer, Mark; Billiau, An D; Dubois, Bénédicte

    2007-06-01

    Autologous hematopoietic stem cell transplantation (HSCT) is being explored in the treatment of severe multiple sclerosis (MS), and is based on the concept of "resetting" the immune system. The use of allogeneic HSCT may offer additional advantages, such as the replacement of the autoreactive immune compartment by healthy allogeneic cells and development of a graft-versus-autoimmunity (GVA) effect. However, in clinical practice, the genetic susceptibility to MS of allogeneic stem cell donors is generally unknown, and GVA may therefore be an important mechanism of action. Experimental autoimmune encephalomyelitis (EAE)-susceptible and -resistant mouse strains were used to determine the roles of genetic susceptibility, level of donor-chimerism, and alloreactivity in the therapeutic potential of syngeneic versus allogeneic bone marrow transplant (BMT) for EAE. After transplantation and EAE induction, animals were evaluated for clinical EAE and ex vivo myelin oligodendrocyte glycoprotein-specific proliferation. Early after BMT, both syngeneic and allogeneic chimeras were protected from EAE development. On the longer term, allogeneic but not syngeneic BMT conferred protection, but this required high-level donor-chimerism from EAE-resistant donors. Importantly, when EAE-susceptible donors were used, robust protection from EAE was obtained when active alloreactivity, induced by donor lymphocyte infusions, was provided. Our findings indicate the requirement of a sufficient level of donor-chimerism from a nonsusceptible donor in the therapeutic effect of allogeneic BMT. Importantly, the data indicate that, independently of genetic susceptibility, active alloreactivity is associated with a GVA effect, thereby providing new evidence to support the potential role of allogeneic BMT in the treatment of MS. PMID:17531772

  19. Evidence Evaluation: Measure "Z" Corresponds to Human Utility Judgments Better than Measure "L" and Optimal-Experimental-Design Models

    ERIC Educational Resources Information Center

    Rusconi, Patrice; Marelli, Marco; D'Addario, Marco; Russo, Selena; Cherubini, Paolo

    2014-01-01

    Evidence evaluation is a crucial process in many human activities, spanning from medical diagnosis to impression formation. The present experiments investigated which, if any, normative model best conforms to people's intuition about the value of the obtained evidence. Psychologists, epistemologists, and philosophers of science have proposed…

  20. Adaptation of an evidence-based intervention to promote colorectal cancer screening: a quasi-experimental study

    PubMed Central

    2014-01-01

    Background To accelerate the translation of research findings into practice for underserved populations, we investigated the adaptation of an evidence-based intervention (EBI), designed to increase colorectal cancer (CRC) screening in one limited English-proficient (LEP) population (Chinese), for another LEP group (Vietnamese) with overlapping cultural and health beliefs. Methods Guided by Diffusion of Innovations Theory, we adapted the EBI to achieve greater reach. Core elements of the adapted intervention included: small media (a DVD and pamphlet) translated into Vietnamese from Chinese; medical assistants distributing the small media instead of a health educator; and presentations on CRC screening to the medical assistants. A quasi-experimental study examined CRC screening adherence among eligible Vietnamese patients at the intervention and control clinics, before and after the 24-month intervention. The proportion of the adherence was assessed using generalized linear mixed models that account for clustering under primary care providers and also within-patient correlation between baseline and follow up. Results Our study included two cross-sectional samples: 1,016 at baseline (604 in the intervention clinic and 412 in the control clinic) and 1,260 post-intervention (746 in the intervention and 514 in the control clinic), including appreciable overlaps between the two time points. Pre-post change in CRC screening over time, expressed as an odds ratio (OR) of CRC screening adherence by time, showed a marginally-significant greater increase in CRC screening adherence at the intervention clinic compared to the control clinic (the ratio of the two ORs = 1.42; 95% CI 0.95, 2.15). In the sample of patients who were non-adherent to CRC screening at baseline, compared to the control clinic, the intervention clinic had marginally-significant greater increase in FOBT (adjusted OR = 1.77; 95% CI 0.98, 3.18) and a statistically-significantly greater increase in CRC