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Sample records for extinction trials alleviates

  1. Reexposure to the Amnestic Agent Alleviates Cycloheximide-Induced Retrograde Amnesia for Reactivated and Extinction Memories

    Science.gov (United States)

    Briggs, James F.; Olson, Brian P.

    2013-01-01

    We investigated whether reexposure to an amnestic agent would reverse amnesia for extinction of learned fear similar to that of a reactivated memory. When cycloheximide (CHX) was administered immediately after a brief cue-induced memory reactivation (15 sec) and an extended extinction session (12 min) rats showed retrograde amnesia for both…

  2. Acute inescapable stress alleviates fear extinction recall deficits caused by serotonin transporter abolishment.

    Science.gov (United States)

    Schipper, Pieter; Henckens, Marloes J A G; Lopresto, Dora; Kozicz, Tamas; Homberg, Judith R

    2018-07-02

    Life stress increases risk for developing post-traumatic stress disorder (PTSD), and more prominently so in short-allele carriers of the serotonin transporter linked polymorphic region (5-HTTLPR). Serotonin transporter knockout (5-HTT -/- ) rats show compromised extinction (recall) of conditioned fear, which might mediate the increased risk for PTSD and reduce the therapeutic efficacy of exposure therapy. Here, we assessed whether acute inescapable stress (IS) differentially affects fear extinction and extinction recall in 5-HTT -/- rats and wildtype controls. Surprisingly, IS experience improved fear extinction recall in 5-HTT -/- rats to the level of wildtype animals, while wildtypes were unaffected by this IS. Thus, whereas 5-HTT -/- rats evidently were more responsive to the stressor, the behavioral consequences presented themselves as adaptive. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  3. Extinction of Pavlovian conditioning: The influence of trial number and reinforcement history.

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    Chan, C K J; Harris, Justin A

    2017-08-01

    Pavlovian conditioning is sensitive to the temporal relationship between the conditioned stimulus (CS) and the unconditioned stimulus (US). This has motivated models that describe learning as a process that continuously updates associative strength during the trial or specifically encodes the CS-US interval. These models predict that extinction of responding is also continuous, such that response loss is proportional to the cumulative duration of exposure to the CS without the US. We review evidence showing that this prediction is incorrect, and that extinction is trial-based rather than time-based. We also present two experiments that test the importance of trials versus time on the Partial Reinforcement Extinction Effect (PREE), in which responding extinguishes more slowly for a CS that was inconsistently reinforced with the US than for a consistently reinforced one. We show that increasing the number of extinction trials of the partially reinforced CS, relative to the consistently reinforced CS, overcomes the PREE. However, increasing the duration of extinction trials by the same amount does not overcome the PREE. We conclude that animals learn about the likelihood of the US per trial during conditioning, and learn trial-by-trial about the absence of the US during extinction. Moreover, what they learn about the likelihood of the US during conditioning affects how sensitive they are to the absence of the US during extinction. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Separation of time-based and trial-based accounts of the partial reinforcement extinction effect.

    Science.gov (United States)

    Bouton, Mark E; Woods, Amanda M; Todd, Travis P

    2014-01-01

    Two appetitive conditioning experiments with rats examined time-based and trial-based accounts of the partial reinforcement extinction effect (PREE). In the PREE, the loss of responding that occurs in extinction is slower when the conditioned stimulus (CS) has been paired with a reinforcer on some of its presentations (partially reinforced) instead of every presentation (continuously reinforced). According to a time-based or "time-accumulation" view (e.g., Gallistel and Gibbon, 2000), the PREE occurs because the organism has learned in partial reinforcement to expect the reinforcer after a larger amount of time has accumulated in the CS over trials. In contrast, according to a trial-based view (e.g., Capaldi, 1967), the PREE occurs because the organism has learned in partial reinforcement to expect the reinforcer after a larger number of CS presentations. Experiment 1 used a procedure that equated partially and continuously reinforced groups on their expected times to reinforcement during conditioning. A PREE was still observed. Experiment 2 then used an extinction procedure that allowed time in the CS and the number of trials to accumulate differentially through extinction. The PREE was still evident when responding was examined as a function of expected time units to the reinforcer, but was eliminated when responding was examined as a function of expected trial units to the reinforcer. There was no evidence that the animal responded according to the ratio of time accumulated during the CS in extinction over the time in the CS expected before the reinforcer. The results thus favor a trial-based account over a time-based account of extinction and the PREE. This article is part of a Special Issue entitled: Associative and Temporal Learning. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Facilitated Extinction Training to Improve Pharmacotherapy for Smoking Cessation: A Pilot Feasibility Trial.

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    Brandon, Thomas H; Unrod, Marina; Drobes, David J; Sutton, Steven K; Hawk, Larry W; Simmons, Vani N; Brandon, Karen O; Roetzheim, Richard G; Meltzer, Lauren R; Miller, Ralph R; Cahill, Shawn P

    2017-09-12

    Varenicline reduces smoking satisfaction during the pre-cessation run-in period, which may contribute to extinction of cravings and smoking behavior. Research indicates that efficacy is enhanced when the run-in period is increased from 1 to 4 weeks, providing a longer extinction opportunity. We hypothesized that efficacy could be further enhanced by harnessing basic and applied research on extinction. We developed a pre-cessation extinction-facilitating intervention and tested its feasibility in a pilot trial. The Facilitated Extinction (FE) intervention comprised brief counseling and a workbook recommending strategies to maximize extinction processes during the run-in, including instructions to smoke at a normal rate across contexts and cues, and use of an extinction cue to enhance generalization. Participants were randomly assigned to 1 of 3 varenicline interventions: standard (1-week run-in), extended (4-week run-in), and extended + FE. Interventions were delivered prior to the target quit date (TQD). Assessments were conducted in weeks 1 and 4 pre-TQD and 1 and 3 months post-TQD, with focus on feasibility indices. Recruitment and retention goals were met (N=58). Treatment satisfaction was high across groups. The majority of FE participants adhered to instructions and maintained their usual smoking rate during the run-in period. Greater decreases in craving and smoking satisfaction were observed among participants in both extended groups versus the standard group (p's<.005). Feasibility was demonstrated. Participants adhered to the FE intervention, thereby optimizing the number and variety of extinction trials. Findings support testing the novel FE smoking cessation intervention in a fully-powered trial. This study expands the research on the clinical benefits of extending the pre-cessation run-in period of varenicline. It introduces the hypothesis that further benefit might be achieved by translating basic behavioral research, as well as cue-exposure research

  6. The probability of reinforcement per trial affects posttrial responding and subsequent extinction but not within-trial responding.

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    Harris, Justin A; Kwok, Dorothy W S

    2018-01-01

    During magazine approach conditioning, rats do not discriminate between a conditional stimulus (CS) that is consistently reinforced with food and a CS that is occasionally (partially) reinforced, as long as the CSs have the same overall reinforcement rate per second. This implies that rats are indifferent to the probability of reinforcement per trial. However, in the same rats, the per-trial reinforcement rate will affect subsequent extinction-responding extinguishes more rapidly for a CS that was consistently reinforced than for a partially reinforced CS. Here, we trained rats with consistently and partially reinforced CSs that were matched for overall reinforcement rate per second. We measured conditioned responding both during and immediately after the CSs. Differences in the per-trial probability of reinforcement did not affect the acquisition of responding during the CS but did affect subsequent extinction of that responding, and also affected the post-CS response rates during conditioning. Indeed, CSs with the same probability of reinforcement per trial evoked the same amount of post-CS responding even when they differed in overall reinforcement rate and thus evoked different amounts of responding during the CS. We conclude that reinforcement rate per second controls rats' acquisition of responding during the CS, but at the same time, rats also learn specifically about the probability of reinforcement per trial. The latter learning affects the rats' expectation of reinforcement as an outcome of the trial, which influences their ability to detect retrospectively that an opportunity for reinforcement was missed, and, in turn, drives extinction. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  7. Galantamine alleviates inflammation and insulin resistance in patients with metabolic syndrome in a randomized trial.

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    Consolim-Colombo, Fernanda M; Sangaleti, Carine T; Costa, Fernando O; Morais, Tercio L; Lopes, Heno F; Motta, Josiane M; Irigoyen, Maria C; Bortoloto, Luiz A; Rochitte, Carlos Eduardo; Harris, Yael Tobi; Satapathy, Sanjaya K; Olofsson, Peder S; Akerman, Meredith; Chavan, Sangeeta S; MacKay, Meggan; Barnaby, Douglas P; Lesser, Martin L; Roth, Jesse; Tracey, Kevin J; Pavlov, Valentin A

    2017-07-20

    Metabolic syndrome (MetS) is an obesity-driven condition of pandemic proportions that increases the risk of type 2 diabetes and cardiovascular disease. Pathophysiological mechanisms are poorly understood, though inflammation has been implicated in MetS pathogenesis. The aim of this study was to assess the effects of galantamine, a centrally acting acetylcholinesterase inhibitor with antiinflammatory properties, on markers of inflammation implicated in insulin resistance and cardiovascular risk, and other metabolic and cardiovascular indices in subjects with MetS. In this randomized, double-blind, placebo-controlled trial, subjects with MetS (30 per group) received oral galantamine 8 mg daily for 4 weeks, followed by 16 mg daily for 8 weeks or placebo. The primary outcome was inflammation assessed through plasma levels of cytokines and adipokines associated with MetS. Secondary endpoints included body weight, fat tissue depots, plasma glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), cholesterol (total, HDL, LDL), triglycerides, BP, heart rate, and heart rate variability (HRV). Galantamine resulted in lower plasma levels of proinflammatory molecules TNF (-2.57 pg/ml [95% CI -4.96 to -0.19]; P = 0.035) and leptin (-12.02 ng/ml [95% CI -17.71 to -6.33]; P < 0.0001), and higher levels of the antiinflammatory molecules adiponectin (2.71 μg/ml [95% CI 1.93 to 3.49]; P < 0.0001) and IL-10 (1.32 pg/ml, [95% CI 0.29 to 2.38]; P = 0.002) as compared with placebo. Galantamine also significantly lowered plasma insulin and HOMA-IR values, and altered HRV. Low-dose galantamine alleviates inflammation and insulin resistance in MetS subjects. These findings support further study of galantamine in MetS therapy. ClinicalTrials.gov, number NCT02283242. Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil, and the NIH.

  8. Smoking cue reactivity across massed extinction trials: negative affect and gender effects.

    Science.gov (United States)

    Collins, Bradley N; Nair, Uma S; Komaroff, Eugene

    2011-04-01

    Designing and implementing cue exposure procedures to treat nicotine dependence remains a challenge. This study tested the hypothesis that gender and negative affect (NA) influence changes in smoking urge over time using data from a pilot project testing the feasibility of massed extinction procedures. Forty-three smokers and ex-smokers completed the behavioral laboratory procedures. All participants were over 17 years old, smoked at least 10 cigarettes daily over the last year (or the year prior to quitting) and had expired CO below 10 ppm at the beginning of the ~4-hour session. After informed consent, participants completed 45 min of baseline assessments, and then completed a series of 12 identical, 5-minute exposure trials with inter-trial breaks. Smoking cues included visual, tactile, and olfactory cues with a lit cigarette, in addition to smoking-related motor behaviors without smoking. After each trial, participants reported urge and negative affect (NA). Logistic growth curve models supported the hypothesis that across trials, participants would demonstrate an initial linear increase followed by a decrease in smoking urge (quadratic effect). Data supported hypothesized gender, NA, and gender×NA effects. Significant linear increases in urge were observed among high and low NA males, but not among females in either NA subgroup. A differential quadratic effect showed a significant decrease in urge for the low NA subgroup, but a non-significant decrease in urge in the high NA group. This is the first study to demonstrate gender differences and the effects of NA on the extinction process using a smoking cue exposure paradigm. Results could guide future cue reactivity research and exposure interventions for nicotine dependence. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Cued Reacquisition Trials during Extinction Weaken Contextual Renewal in Human Predictive Learning

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    Effting, Marieke; Vervliet, Bram; Beckers, Tom; Kindt, Merel

    2013-01-01

    Extinction is generally more context specific than acquisition, as illustrated by the renewal effect. While most strategies to counteract renewal focus on decreasing the context specificity of extinction, the present work aimed at increasing the context specificity of acquisition learning. Two experiments examined whether presenting cued…

  10. Repeated tender point injections of granisetron alleviate chronic myofascial pain--a randomized, controlled, double-blinded trial.

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    Christidis, Nikolaos; Omrani, Shahin; Fredriksson, Lars; Gjelset, Mattias; Louca, Sofia; Hedenberg-Magnusson, Britt; Ernberg, Malin

    2015-01-01

    Serotonin (5-HT) mediates pain by peripheral 5-HT3-receptors. Results from a few studies indicate that intramuscular injections of 5-HT3-antagonists may reduce musculoskeletal pain. The aim of this study was to investigate if repeated intramuscular tender-point injections of the 5-HT3-antagonist granisetron alleviate pain in patients with myofascial temporomandibular disorders (M-TMD). This prospective, randomized, controlled, double blind, parallel-arm trial (RCT) was carried out during at two centers in Stockholm, Sweden. The randomization was performed by a researcher who did not participate in data collection with an internet-based application ( www.randomization.com ). 40 patients with a diagnose of M-TMD according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were randomized to receive repeated injections, one week apart, with either granisetron (GRA; 3 mg) or isotonic saline as control (CTR). The median weekly pain intensities decreased significantly at all follow-ups (1-, 2-, 6-months) in the GRA-group (Friedman test; P  0.075). The numbers needed to treat (NNT) were 4 at the 1- and 6-month follow-ups, and 3.3 at the 2-month follow-up in favor of granisetron. Repeated intramuscular tender-point injections with granisetron provide a new pharmacological treatment possibility for myofascial pain patients with repeated intramuscular tender-point injections with the serotonin type 3 antagonist granisetron. It showed a clinically relevant pain reducing effect in the temporomandibular region, both in a short- and long-term aspect. European Clinical Trials Database 2005-006042-41 as well as at Clinical Trials NCT02230371 .

  11. Alteration of synaptic transmission in the hippocampal-mPFC pathway during extinction trials of context-dependent fear memory in juvenile rat stress models.

    Science.gov (United States)

    Koseki, Hiroyo; Matsumoto, Machiko; Togashi, Hiroko; Miura, Yoshihide; Fukushima, Kazuaki; Yoshioka, Mitsuhiro

    2009-09-01

    The medial prefrontal cortex (mPFC) has been proposed to be essential for extinction of fear memory, but its neural mechanism has been poorly understood. The present study examined whether synaptic transmission in the hippocampal-mPFC pathway is related to extinction of context-dependent fear memory in freely moving rats using electrophysiological approaches combined with behavioral analysis. Population spike amplitude in the mPFC was decreased during the first extinction trial by exposure to contextual fear conditioning. This synaptic inhibition was reversed by repeated extinction trials, accompanied by decreases in fear-related freezing behavior. These results suggest that alteration of synaptic transmission in the hippocampal-mPFC pathway is associated with the extinction processes of context-dependent fear memory. Further experiments were performed to elucidate whether early postnatal stress alters the synaptic response in the mPFC during extinction trials using a juvenile stress model, based on our previous findings that early postnatal stress affects the behavioral response to emotional stress. Adult rats that previously were exposed to five footshocks (FS) (shock intensity, 0.5 mA; intershock interval, 28 seconds; shock duration, 2 seconds) at postnatal day 21 to 25 (week 3; 3W-FS) exhibited impaired reversal of both inhibitory synaptic transmission and freezing behavior induced by repeated extinction trials. The neuronal and behavioral deficits observed in the 3W-FS group were prevented by pretreatment with the serotonin(1A) receptor agonist tandospirone (1 mg/kg, i.p.). These results indicate the possiblity that aversive stress exposure during the third postnatal week impaired extinction processes of context-dependent fear memory. The deficits in extinction observed in the 3W-FS group might be attributable to dysfunction of hippocampal-mPFC neural circuits involving 5-HT(1A) receptor mechanisms. 2009 Wiley-Liss, Inc.

  12. Protocol for the Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) study: a pragmatic, randomised clinical trial

    Science.gov (United States)

    Wildes, T S; Winter, A C; Maybrier, H R; Mickle, A M; Lenze, E J; Stark, S; Lin, N; Inouye, S K; Schmitt, E M; McKinnon, S L; Muench, M R; Murphy, M R; Upadhyayula, R T; Fritz, B A; Escallier, K E; Apakama, G P; Emmert, D A; Graetz, T J; Stevens, T W; Palanca, B J; Hueneke, R L; Melby, S; Torres, B; Leung, J; Jacobsohn, E; Avidan, M S

    2016-01-01

    Introduction Postoperative delirium, arbitrarily defined as occurring within 5 days of surgery, affects up to 50% of patients older than 60 after a major operation. This geriatric syndrome is associated with longer intensive care unit and hospital stay, readmission, persistent cognitive deterioration and mortality. No effective preventive methods have been identified, but preliminary evidence suggests that EEG monitoring during general anaesthesia, by facilitating reduced anaesthetic exposure and EEG suppression, might decrease incident postoperative delirium. This study hypothesises that EEG-guidance of anaesthetic administration prevents postoperative delirium and downstream sequelae, including falls and decreased quality of life. Methods and analysis This is a 1232 patient, block-randomised, double-blinded, comparative effectiveness trial. Patients older than 60, undergoing volatile agent-based general anaesthesia for major surgery, are eligible. Patients are randomised to 1 of 2 anaesthetic approaches. One group receives general anaesthesia with clinicians blinded to EEG monitoring. The other group receives EEG-guidance of anaesthetic agent administration. The outcomes of postoperative delirium (≤5 days), falls at 1 and 12 months and health-related quality of life at 1 and 12 months will be compared between groups. Postoperative delirium is assessed with the confusion assessment method, falls with ProFaNE consensus questions and quality of life with the Veteran's RAND 12-item Health Survey. The intention-to-treat principle will be followed for all analyses. Differences between groups will be presented with 95% CIs and will be considered statistically significant at a two-sided pAnesthesia to Alleviate Geriatric Syndromes (ENGAGES) is approved by the ethics board at Washington University. Recruitment began in January 2015. Dissemination plans include presentations at scientific conferences, scientific publications, internet-based educational materials and

  13. Probiotics are effective in alleviating infantile colic; results of a randomized controlled trial held at benazir bhutto hospital rawalpindi, pakistan

    International Nuclear Information System (INIS)

    Ashraf, M.W.; Ayaz, S.B.; Ashraf, M.N.

    2015-01-01

    Objectives: This study aimed to assess the role of probiotics in alleviating infantile colic (IC) while targeting local population. In case of a positive outcome, its use could be suggested in pediatric health care facilities. Methodology: It was a non-blinded randomized control trial conducted at the department of pediatrics, Benazir Bhutto Hospital, Rawalpindi from 4th October 2012 to 3rd April 2013. Through non-probability consecutive sampling we included breast-fed infants of either sex of age 3 weeks (21 days) to 3 months (90 days) diagnosed with IC based on Wessel description. We divided them into two groups i.e. group-A and B who were given probiotics containing Lactobacillus reuteri and simethicone respectively. Results: Of 90 children, 45 children were in each group. Group-A had a mean age 48 ± 17 days and group-B had a mean age 50 ± 17 days. Maximum infants were in sub-group 21 - 45 days (55.6% and 51.1% respectively) in both the groups. The male gender dominated both groups (64.4% and 57.7% respectively). Significantly large percentage (p<0.001) of infants in group-A (86.7%) reached the landmark set for the efficacy confirmation than group-B (51.1%). The mean crying time for the group-A (39 ± 53 minutes) at the end of treatment was significantly shorter (p<0.001) than that of group-B (113 ± 54 minutes). No side effect was reported in the whole sample. Conclusion: Probiotics containing Lactobacillus reuteri significantly improved symptoms in managing IC than simethicaone with no side effects. (author)

  14. Facilitation of fear extinction in phobic participants with a novel cognitive enhancer: a randomized placebo controlled trial of yohimbine augmentation

    NARCIS (Netherlands)

    Powers, M.B.; Smits, J.A.J.; Otto, M.W.; Sanders, C.; Emmelkamp, P.M.G.

    2009-01-01

    Preliminary animal research suggests that yohimbine hydrochloride, a selective competitive alpha2-adrenergic receptor antagonist, accelerates fear extinction and converts ineffective extinction regimens (long intertrial intervals) to effective ones. This randomized placebo controlled study examined

  15. A web-based training program using cognitive behavioral therapy to alleviate psychological distress among employees: randomized controlled pilot trial.

    Science.gov (United States)

    Mori, Makiko; Tajima, Miyuki; Kimura, Risa; Sasaki, Norio; Somemura, Hironori; Ito, Yukio; Okanoya, June; Yamamoto, Megumi; Nakamura, Saki; Tanaka, Katsutoshi

    2014-12-02

    A number of psychoeducational programs based on cognitive behavioral therapy (CBT) to alleviate psychological distress have been developed for implementation in clinical settings. However, while these programs are considered critical components of stress management education in a workplace setting, they are required to be brief and simple to implement, which can hinder development. The intent of the study was to examine the effects of a brief training program based on CBT in alleviating psychological distress among employees and facilitating self-evaluation of stress management skills, including improving the ability to recognize dysfunctional thinking patterns, transform dysfunctional thoughts to functional ones, cope with stress, and solve problems. Of the 187 employees at an information technology company in Tokyo, Japan, 168 consented to participate in our non-blinded randomized controlled study. The training group received CBT group education by a qualified CBT expert and 1 month of follow-up Web-based CBT homework. The effects of this educational program on the psychological distress and stress management skills of employees were examined immediately after completion of training and then again after 6 months. Although the training group did exhibit lower mean scores on the Kessler-6 (K6) scale for psychological distress after 6 months, the difference from the control group was not significant. However, the ability of training group participants to recognize dysfunctional thinking was significantly improved both immediately after training completion and after 6 months. While the ability of participants to cope with stress was not significantly improved immediately after training, improvement was noted after 6 months in the training group. No notable improvements were observed in the ability of participants to transform thoughts from dysfunctional to functional or in problem-solving skills. A sub-analysis of participants who initially exhibited clinically

  16. A comparative trial of ice application versus EMLA cream in alleviation of pain during botulinum toxin injections for palmar hyperhidrosis.

    Science.gov (United States)

    Alsantali, Adel

    2018-01-01

    Botulinum toxin is a safe and effective therapy for palmar hyperhidrosis, but the associated pain from injections limits the usefulness of this method of treatment. To evaluate the efficacy of Eutectic Mixture of Local Anesthetics (EMLA) cream versus ice application in alleviation of pain during botulinum toxin injections for palmar hyperhidrosis. In this prospective study, 23 patients underwent palm Botox injections to treat their excessive sweating. In each patient, EMLA cream was applied to one palm and ice was applied directly before the injections in the other palm. Pain was evaluated using a Visual Analog Scale. Statistically, there was a significant difference in pain control between EMLA cream group and ice application group ( p cream was applied was 8.9 (SD=0.81), whereas it was 4.8 (±0.9) in the ice group. In this study, the successful use of ice application in reducing pain by 40% in comparison to EMLA cream during Botox toxin injection for palmar hyperhidrosis is demonstrated.

  17. A comparative trial of ice application versus EMLA cream in alleviation of pain during botulinum toxin injections for palmar hyperhidrosis

    Directory of Open Access Journals (Sweden)

    Alsantali A

    2018-04-01

    Full Text Available Adel Alsantali Department of Dermatology, King Fahd Armed Forces Hospital, Jeddah, Saudi Arabia Background: Botulinum toxin is a safe and effective therapy for palmar hyperhidrosis, but the associated pain from injections limits the usefulness of this method of treatment. Purpose: To evaluate the efficacy of Eutectic Mixture of Local Anesthetics (EMLA cream versus ice application in alleviation of pain during botulinum toxin injections for palmar hyperhidrosis. Methods: In this prospective study, 23 patients underwent palm Botox injections to treat their excessive sweating. In each patient, EMLA cream was applied to one palm and ice was applied directly before the injections in the other palm. Pain was evaluated using a Visual Analog Scale. Results: Statistically, there was a significant difference in pain control between EMLA cream group and ice application group (p<0.05. The average pain score on the hands where EMLA cream was applied was 8.9 (SD=0.81, whereas it was 4.8 (±0.9 in the ice group. Conclusion: In this study, the successful use of ice application in reducing pain by 40% in comparison to EMLA cream during Botox toxin injection for palmar hyperhidrosis is demonstrated.Keywords: ice, local anesthetics, EMLA, palmar hyperhidrosis, Botox injection, pain reduction

  18. Rethinking Extinction

    Science.gov (United States)

    Dunsmoor, Joseph E.; Niv, Yael; Daw, Nathaniel; Phelps, Elizabeth A.

    2015-01-01

    Extinction serves as the leading theoretical framework and experimental model to describe how learned behaviors diminish through absence of anticipated reinforcement. In the past decade, extinction has moved beyond the realm of associative learning theory and behavioral experimentation in animals and has become a topic of considerable interest in the neuroscience of learning, memory, and emotion. Here, we review research and theories of extinction, both as a learning process and as a behavioral technique, and consider whether traditional understandings warrant a re-examination. We discuss the neurobiology, cognitive factors, and major computational theories, and revisit the predominant view that extinction results in new learning that interferes with expression of the original memory. Additionally, we reconsider the limitations of extinction as a technique to prevent the relapse of maladaptive behavior, and discuss novel approaches, informed by contemporary theoretical advances, that augment traditional extinction methods to target and potentially alter maladaptive memories. PMID:26447572

  19. Rethinking Extinction

    OpenAIRE

    Dunsmoor, Joseph E.; Niv, Yael; Daw, Nathaniel; Phelps, Elizabeth A.

    2015-01-01

    Extinction serves as the leading theoretical framework and experimental model to describe how learned behaviors diminish through absence of anticipated reinforcement. In the past decade, extinction has moved beyond the realm of associative learning theory and behavioral experimentation in animals and has become a topic of considerable interest in the neuroscience of learning, memory, and emotion. Here, we review research and theories of extinction, both as a learning process and as a behavior...

  20. Alleviation of mandibular anterior crowding with copper-nickel-titanium vs nickel-titanium wires: a double-blind randomized control trial.

    Science.gov (United States)

    Pandis, Nikolaos; Polychronopoulou, Argy; Eliades, Theodore

    2009-08-01

    The purpose of this study was to investigate the efficiency of copper-nickel-titanium (CuNiTi) vs nickel-titanium (NiTi) archwires in resolving crowding of the anterior mandibular dentition. Sixty patients were included in this single-center, single-operator, double-blind randomized trial. All patients were bonded with the In Ovation-R self-ligating bracket (GAC, Central Islip, NY) with a 0.022-in slot, and the amount of crowding of the mandibular anterior dentition was assessed by using the irregularity index. The patients were randomly allocated into 2 groups of 30 patients, each receiving a 0.016-in CuNiTi 35 degrees C (Ormco, Glendora, Calif) or a 0.016-in NiTi (ModernArch, Wyomissing, Pa) wire. The type of wire selected for each patient was not disclosed to the provider or the patient. The date that each patient received a wire was recorded, and all patients were followed monthly for a maximum of 6 months. Demographic and clinical characteristics between the 2 wire groups were compared with the t test or the chi-square test and the Fisher exact test. Time to resolve crowding was explored with statistical methods for survival analysis, and alignment rate ratios for wire type and crowding level were calculated with Cox proportional hazards multivariate modeling. The type of wire (CuNiTi vs NiTi) had no significant effect on crowding alleviation (129.4 vs 121.4 days; hazard ratio, 1.3; P >0.05). Severe crowding (>5 on the irregularity index) showed a significantly higher probability of crowding alleviation duration relative to dental arches with a score of wires in laboratory and clinical conditions might effectively eliminate the laboratory-derived advantage of CuNiTi wires.

  1. Electroacupuncture to alleviate postoperative pain after a laparoscopic appendectomy: study protocol for a three-arm, randomised, controlled trial.

    Science.gov (United States)

    Lee, Seunghoon; Nam, Dongwoo; Kwon, Minsoo; Park, Won Seo; Park, Sun Jin

    2017-08-04

    The purpose of this study is to evaluate the efficacy and safety of electroacupuncture (EA) for postoperative pain after laparoscopic appendectomy compared with sham electroacupuncture (SEA) and no acupuncture treatment. This study is a protocol for a three-arm, randomised, patient-assessor-blinded (to the type of acupuncture treatment), controlled, parallel trial. 138 participants diagnosed with appendicitis and scheduled for laparoscopic appendectomy will be randomly assigned to the EA group (n=46), SEA group (n=46) or control group (n=46). The EA group will receive acupuncture treatment at both regional and distal acupuncture points with electrostimulation. The SEA group will receive sham acupuncture treatment with mock electrostimulation. Both EA and SEA groups will receive a total of four treatments 1 hour preoperative, 1 hour postoperative and during the morning and afternoon the day after surgery with the same routine postoperative pain control. The control group will receive only routine postoperative pain control. The primary outcome is the 11-point Pain Intensity Numerical Rating Scale (PI-NRS) at 24 hours after surgery. The secondary outcomes are the PI-NRS, analgesic consumption, opioid-related side effects, time to first passing flatus, quality of life and adverse events evaluated 6, 12, 24 and 36 hours and 7 days after surgery. The study was planned in accordance with the Helsinki Declaration and the Korean Good Clinical Practice Guidelines to protect the participants and was approved by the institutional review board (IRB) of Kyung Hee University Medical Center (KMC IRB-1427-02). The results will be disseminated in peer-reviewed journals and presented at international conferences. Clinical Research Information Service (KCT0001328). © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  2. The Relaxation Exercise and Social Support Trial (RESST: a community-based randomized controlled trial to alleviate medically unexplained vaginal discharge symptoms

    Directory of Open Access Journals (Sweden)

    Kobeissi Loulou

    2012-11-01

    Full Text Available Abstract Background Symptoms such as medically unexplained vaginal discharge (MUVD are common and bothersome, leading to potentially unnecessary use of resources. Methods A community-based individually randomized controlled trial to assess the effectiveness of a relatively simple, culturally appropriate multi-component intervention on reducing reported MUVD, among women suffering from low-moderate levels of common mental distress. The setting was a socio-economically deprived, informal settlement in the southern suburbs of Beirut, Lebanon. The intervention comprised up to 12 group sessions implemented over a six-week period, each divided into a psychosocial and a relaxation exercise component. The primary outcome was self-reported MUVD, which was defined as a complaint of vaginal discharge upon ruling out reproductive tract infections (RTIs, through lab analysis. Anxiety and/or depression symptoms were the secondary outcomes for this trial. These were assessed using an Arabic validated version of the Hopkins Symptoms Checklist-25 (HSCL-25. Assessments were done at baseline and six months using face-to face interviews, pelvic examinations and laboratory tests. Women were randomized into either intervention or control group. Blinding on the intervention status was not possible for both logistic and ethical reasons, especially as knowledge of involvement in the intervention was integral to its delivery. Intent to treat analysis was used. Results Of 75 women randomized to the intervention, 48% reported MUVD at 6 months compared with 63% of 73 in the control group (difference of -15%, 95% confidence interval (CI -31%, 0%, p=0.067. Adjustments for baseline imbalances and any factors relating to consent had no appreciable effect on these results. The risk of MUVD was reduced in absolute terms by 2.4% for each intervention session attended (95% CI -4.9%, 0.0%, p=0.049. While there was also marginal evidence of a beneficial effect on anxiety, there was

  3. Neural activity in ventral medial prefrontal cortex is modulated more before approach than avoidance during reinforced and extinction trial blocks.

    Science.gov (United States)

    Gentry, Ronny N; Roesch, Matthew R

    2018-04-16

    Ventromedial prefrontal cortex (vmPFC) is thought to provide regulatory control over Pavlovian fear responses and has recently been implicated in appetitive approach behavior, but much less is known about its role in contexts where appetitive and aversive outcomes can be obtained and avoided, respectively. To address this issue, we recorded from single neurons in vmPFC while male rats performed our combined approach and avoidance task under reinforced and non-reinforced (extinction) conditions. Surprisingly, we found that cues predicting reward modulated cell firing in vmPFC more often and more robustly than cues preceding avoidable shock; additionally, firing of vmPFC neurons was both response (press or no-press) and outcome (reinforced or extinction) selective. These results suggest a complex role for vmPFC in regulating behavior and supports its role in appetitive contexts during both reinforced and non-reinforced conditions. SIGNIFICANCE STATEMENT Selecting context-appropriate behaviors to gain reward or avoid punishment is critical for survival. While the role of ventromedial prefrontal cortex (vmPFC) in mediating fear responses is well-established, vmPFC has also been implicated in the regulation of reward-guided approach and extinction. Many studies have used indirect methods and simple behavioral procedures to study vmPFC, which leaves the literature incomplete. We recorded vmFPC neural activity during a complex cue-driven combined approach and avoidance task and during extinction. Surprisingly, we found very little vmPFC modulation to cues predicting avoidable shock, while cues predicting reward approach robustly modulated vmPFC firing in a response- and outcome-selective manner. This suggests a more complex role for vmPFC than current theories suggest, specifically regarding context-specific behavioral optimization. Copyright © 2018 the authors.

  4. Does transcutaneous electrical nerve stimulation (TENS) alleviate the pain experienced during bone marrow sampling in addition to standard techniques? A randomised, double-blinded, controlled trial.

    Science.gov (United States)

    Tucker, David L; Rockett, Mark; Hasan, Mehedi; Poplar, Sarah; Rule, Simon A

    2015-06-01

    Bone marrow aspiration and trephine (BMAT) biopsies remain important tests in haematology. However, the procedures can be moderately to severely painful despite standard methods of pain relief. To test the efficacy of transcutaneous electrical nerve stimulation (TENS) in alleviating the pain from BMAT in addition to standard analgesia using a numerical pain rating scale (NRS). 70 patients requiring BMAT were randomised (1:1) in a double-blind, placebo-controlled trial. -35 patients received TENS impulses at a strong but comfortable amplitude (intervention group) and 35 patients received TENS impulses just above the sensory threshold (control group) (median pulse amplitude 20 and 7 mA, respectively). Patients and operators were blinded to group allocation. Pain assessments were made using a numerical pain scale completed after the procedure. No significant difference in NRS pain recalled after the procedure was detected (median pain score 5.7 (95% CI 4.8 to 6.6) in control vs 5.6 (95% CI 4.8 to 6.4) in the intervention group). However, 100% of patients who had previous experience of BMAT and >94% of participants overall felt they benefited from using TENS and would recommend it to others for this procedure. There were no side effects from the TENS device, and it was well tolerated. TENS is a safe, non-invasive adjunct to analgesia for reducing pain during bone marrow biopsy and provides a subjective benefit to most users; however, no objective difference in pain scores was detected when using TENS in this randomised controlled study. NCT02005354. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  5. Efficacy of Turmeric Extracts and Curcumin for Alleviating the Symptoms of Joint Arthritis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.

    Science.gov (United States)

    Daily, James W; Yang, Mini; Park, Sunmin

    2016-08-01

    Although turmeric and its curcumin-enriched extracts have been used for treating arthritis, no systematic review and meta-analysis of randomized clinical trials (RCTs) have been conducted to evaluate the strength of the research. We systemically evaluated all RCTs of turmeric extracts and curcumin for treating arthritis symptoms to elucidate the efficacy of curcuma for alleviating the symptoms of arthritis. Literature searches were conducted using 12 electronic databases, including PubMed, Embase, Cochrane Library, Korean databases, Chinese medical databases, and Indian scientific database. Search terms used were "turmeric," "curcuma," "curcumin," "arthritis," and "osteoarthritis." A pain visual analogue score (PVAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were used for the major outcomes of arthritis. Initial searches yielded 29 articles, of which 8 met specific selection criteria. Three among the included RCTs reported reduction of PVAS (mean difference: -2.04 [-2.85, -1.24]) with turmeric/curcumin in comparison with placebo (P curcumin treatment (mean difference: -15.36 [-26.9, -3.77]; P = .009). Furthermore, there was no significant mean difference in PVAS between turmeric/curcumin and pain medicine in meta-analysis of five studies. Eight RCTs included in the review exhibited low to moderate risk of bias. There was no publication bias in the meta-analysis. In conclusion, these RCTs provide scientific evidence that supports the efficacy of turmeric extract (about 1000 mg/day of curcumin) in the treatment of arthritis. However, the total number of RCTs included in the analysis, the total sample size, and the methodological quality of the primary studies were not sufficient to draw definitive conclusions. Thus, more rigorous and larger studies are needed to confirm the therapeutic efficacy of turmeric for arthritis.

  6. Alleviating Parenting Stress in Parents with Intellectual Disabilities : A Randomized Controlled Trial of a Video-feedback Intervention to Promote Positive Parenting

    NARCIS (Netherlands)

    Hodes, Marja W.; Meppelder, Marieke; de Moor, Marleen; Kef, Sabina; Schuengel, Carlo

    2017-01-01

    Background: Adapted parenting support may alleviate the high levels of parenting stress experienced by many parents with intellectual disabilities. Methods: Parents with mild intellectual disabilities or borderline intellectual functioning were randomized to experimental (n = 43) and control

  7. Effects of D-cycloserine on extinction of mesolimbic cue reactivity in alcoholism: a randomized placebo-controlled trial.

    Science.gov (United States)

    Kiefer, Falk; Kirsch, Martina; Bach, Patrick; Hoffmann, Sabine; Reinhard, Iris; Jorde, Anne; von der Goltz, Christoph; Spanagel, Rainer; Mann, Karl; Loeber, Sabine; Vollstädt-Klein, Sabine

    2015-07-01

    Mesocorticolimbic reactivity to alcohol-associated cues has been shown to be associated with relapse to renewed drinking and to be decreased by cue-exposure-based extinction training (CET). Evidence from preclinical studies suggests that the extinction of conditioned alcohol-seeking behavior might be facilitated by drugs increasing N-methyl-D-aspartate (NMDA) receptor-associated memory consolidation. In this study, we assessed the efficacy of CET treatment supplemented with the partial NMDA-receptor agonist D-cycloserine (DCS) at reducing mesolimbic cue reactivity (CR), craving, and relapse risk in alcoholism. In a randomized, placebo-controlled, double-blind study, we recruited 76 recently detoxified abstinent alcohol-dependent patients. Thirty-two (16 DCS, 16 placebo) patients showed cue-induced ventral-striatal activation measured with functional magnetic resonance imaging (fMRI) prior to treatment and were thus included in the efficacy analyses. After inpatient detoxification, patients underwent nine sessions of CET spaced over 3 weeks, receiving either 50 mg DCS or placebo 1 h prior to each CET session. FMRI was conducted before treatment and 3 weeks after treatment onset. Following treatment with CET plus DCS, cue-induced brain activation in the ventral and dorsal striatum was decreased compared to treatment with CET plus placebo. Elevated posttreatment ventral striatal CR and increased craving (assessed using the Obsessive Compulsive Drinking Scale) were associated with increased relapse risk. DCS was shown to augment the effect of CET for alcohol-dependent subjects. The interaction between craving and ventral-striatal CR on treatment outcome suggests that CET might be especially effective in patients exhibiting both high craving and elevated CR.

  8. Efficacy of Turmeric Extracts and Curcumin for Alleviating the Symptoms of Joint Arthritis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

    Science.gov (United States)

    Daily, James W.; Yang, Mini

    2016-01-01

    Abstract Although turmeric and its curcumin-enriched extracts have been used for treating arthritis, no systematic review and meta-analysis of randomized clinical trials (RCTs) have been conducted to evaluate the strength of the research. We systemically evaluated all RCTs of turmeric extracts and curcumin for treating arthritis symptoms to elucidate the efficacy of curcuma for alleviating the symptoms of arthritis. Literature searches were conducted using 12 electronic databases, including PubMed, Embase, Cochrane Library, Korean databases, Chinese medical databases, and Indian scientific database. Search terms used were “turmeric,” “curcuma,” “curcumin,” “arthritis,” and “osteoarthritis.” A pain visual analogue score (PVAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were used for the major outcomes of arthritis. Initial searches yielded 29 articles, of which 8 met specific selection criteria. Three among the included RCTs reported reduction of PVAS (mean difference: −2.04 [−2.85, −1.24]) with turmeric/curcumin in comparison with placebo (P < .00001), whereas meta-analysis of four studies showed a decrease of WOMAC with turmeric/curcumin treatment (mean difference: −15.36 [−26.9, −3.77]; P = .009). Furthermore, there was no significant mean difference in PVAS between turmeric/curcumin and pain medicine in meta-analysis of five studies. Eight RCTs included in the review exhibited low to moderate risk of bias. There was no publication bias in the meta-analysis. In conclusion, these RCTs provide scientific evidence that supports the efficacy of turmeric extract (about 1000 mg/day of curcumin) in the treatment of arthritis. However, the total number of RCTs included in the analysis, the total sample size, and the methodological quality of the primary studies were not sufficient to draw definitive conclusions. Thus, more rigorous and larger studies are needed to confirm the therapeutic efficacy

  9. Efficacy of pudendal nerve block for alleviation of catheter-related bladder discomfort in male patients undergoing lower urinary tract surgeries: A randomized, controlled, double-blind trial.

    Science.gov (United States)

    Xiaoqiang, Li; Xuerong, Zhang; Juan, Liu; Mathew, Bechu Shelley; Xiaorong, Yin; Qin, Wan; Lili, Luo; Yingying, Zhu; Jun, Luo

    2017-12-01

    Catheter-related bladder discomfort (CRBD) to an indwelling urinary catheter is defined as a painful urethral discomfort, resistant to conventional opioid therapy, decreasing the quality of postoperative recovery. According to anatomy, the branches of sacral somatic nerves form the afferent nerves of the urethra and bladder triangle, which deriving from the ventral rami of the second to fourth sacral spinal nerves, innervating the urethral muscles and sphincter of the perineum and pelvic floor; as well as providing sensation to the penis and clitoris in males and females, which including the urethra and bladder triangle. Based on this theoretical knowledge, we formed a hypothesis that CRBD could be prevented by pudendal nerve block. To evaluate if bilateral nerve stimulator-guided pudendal nerve block could relieve CRBD through urethra discomfort alleviation. Single-center randomized parallel controlled, double blind trial conducted at West China Hospital, Sichuan University, China. One hundred and eighty 2 male adult patients under general anesthesia undergoing elective trans-urethral resection of prostate (TURP) or trans-urethral resection of bladder tumor (TURBT). Around 4 out of 182 were excluded, 178 patients were randomly allocated into pudendal and control groups, using computer-generated randomized numbers in a sealed envelope method. A total of 175 patients completed the study. Pudendal group received general anesthesia along with nerve-stimulator-guided bilateral pudendal nerve block and control group received general anesthesia only. Incidence and severity of CRBD; and postoperative VAS score of pain. CRBD incidences were significantly lower in pudendal group at 30 minutes (63% vs 82%, P = .004), 2 hours (64% vs 90%, P < .000), 8 hours (58% vs 79%, P = .003) and 12 hours (52% vs 69%, P = .028) also significantly lower incidence of moderate to severe CRBD in pudendal group at 30 minutes (29% vs 57%, P < .001), 2 hours (22

  10. Interstellar Extinction

    OpenAIRE

    Gontcharov, George

    2017-01-01

    This review describes our current understanding of interstellar extinction. This differ substantially from the ideas of the 20th century. With infrared surveys of hundreds of millions of stars over the entire sky, such as 2MASS, SPITZER-IRAC, and WISE, we have looked at the densest and most rarefied regions of the interstellar medium at distances of a few kpc from the sun. Observations at infrared and microwave wavelengths, where the bulk of the interstellar dust absorbs and radiates, have br...

  11. Nature and Causes of the Immediate Extinction Deficit: A Brief Review

    OpenAIRE

    Maren, Stephen

    2013-01-01

    Recent data in both rodents and humans suggests that the timing of extinction trials after conditioning influences the magnitude and duration of extinction. For example, administering extinction trials soon after Pavlovian fear conditioning in rats, mice, and humans results in minimal fear suppression--the so-called immediate extinction deficit. Here I review recent work examining the behavioral and neural substrates of the immediate extinction deficit. I suggest that extinction is most effec...

  12. Open-field exposure facilitates consummatory extinction.

    Science.gov (United States)

    Justel, Nadia; Psyrdellis, Mariana; Pautassi, Ricardo M

    2016-12-07

    During extinction, the organism learns that a conditioned stimulus or a conditioned response is no longer associated with an unconditioned stimulus, and as a consequence, a decrement in the response is presented. The exposure to novel situations (e.g. exploration of a novel open field) has been used widely to modulate (i.e. either enhance or deteriorate) learning and memory. The aim of the present study was to test whether open-field exposure could modulate consummatory extinction. The results indicated that open-field exposure accelerated the extinction response (i.e. experimental animals provided novelty exposure had lower consummatory behavior than control animals) when applied before - but not after - the first extinction trial, or when applied before the second extinction trial. The results suggest that environmental treatments such as novelty exposure provide a valuable, nonpharmacological alternative to potentially modulate extinction processes.

  13. Alleviating Parenting Stress in Parents with Intellectual Disabilities: A Randomized Controlled Trial of a Video-Feedback Intervention to Promote Positive Parenting

    Science.gov (United States)

    Hodes, Marja W.; Meppelder, Marieke; Moor, Marleen; Kef, Sabina; Schuengel, Carlo

    2017-01-01

    Background: Adapted parenting support may alleviate the high levels of parenting stress experienced by many parents with intellectual disabilities. Methods: Parents with mild intellectual disabilities or borderline intellectual functioning were randomized to experimental (n = 43) and control (n = 42) conditions. Parents in both groups received…

  14. Alleviation of insulin resistance and liver damage by oral administration of Imm124-E is mediated by increased Tregs and associated with increased serum GLP-1 and adiponectin: results of a phase I/II clinical trial in NASH

    Directory of Open Access Journals (Sweden)

    Mizrahi M

    2012-12-01

    Full Text Available Meir Mizrahi,1 Yehudit Shabat,1 Ami Ben Ya'acov,1 Gadi Lalazar,1 Tomer Adar,1 Victor Wong,2 Brian Muller,2 Grant Rawlin,2 Yaron Ilan11Liver Unit, Hebrew University-Hadassah Medical Center, Jerusalem, Israel; 2Immuron Limited, North Melbourne, AustraliaBackground: Nonalcoholic steatohepatitis (NASH is considered to be part of the nonalcoholic fatty liver disorders and its incidence is increasing. Imm124-E (Immuron Ltd, Melbourne, Australia, containing hyperimmune bovine colostrum, has been shown to exert an immunomodulatory effect and to alleviate target organ damage in animal models of NASH. The aim of our study was to determine the safety and efficacy of oral administration of Imm124-E to patients with insulin resistance and NASH.Methods: In an open-label trial, ten patients with biopsy-proven NASH and insulin resistance were orally treated with Imm124-E for 30 days.Results: Oral administration of Imm124-E was safe, and no side effects were noted. Alleviation of insulin resistance was reflected by significantly improved hemoglobin A1c (HbA1c values in all ten treated patients. For between five and eight responders, the following effects were noted: a decrease in fasting glucose levels; improved oral glucose tolerance test (OGGT and homeostatic model assessment insulin resistance (HOMA scores; and alleviation in lipid profile. These effects were accompanied by increased serum levels of glucagon-like peptide 1 (GLP-1, adiponectin and T regulatory cells.Conclusion: Hyperimmune colostrum alleviates NASH.Keywords: NASH, anti-LPS, diabetes, adipokines, regulatory T cells

  15. Rescaling of temporal expectations during extinction

    Science.gov (United States)

    Drew, Michael R.; Walsh, Carolyn; Balsam, Peter D

    2016-01-01

    Previous research suggests that extinction learning is temporally specific. Changing the CS duration between training and extinction can facilitate the loss of the CR within the extinction session but impairs long-term retention of extinction. In two experiments using conditioned magazine approach with rats, we examined the relation between temporal specificity of extinction and CR timing. In Experiment 1 rats were trained on a 12-s, fixed CS-US interval and then extinguished with CS presentations that were 6, 12, or 24 s in duration. The design of Experiment 2 was the same except rats were trained using partial rather than continuous reinforcement. In both experiments, extending the CS duration in extinction facilitated the diminution of CRs during the extinction session, but shortening the CS duration failed to slow extinction. In addition, extending (but not shortening) the CS duration caused temporal rescaling of the CR, in that the peak CR rate migrated later into the trial over the course of extinction training. This migration partially accounted for the faster loss of the CR when the CS duration was extended. Results are incompatible with the hypothesis that extinction is driven by cumulative CS exposure and suggest that temporally extended nonreinforced CS exposure reduces conditioned responding via temporal displacement rather than through extinction per se. PMID:28045291

  16. Impossible Extinction

    Science.gov (United States)

    Cockell, Charles S.

    2003-03-01

    Every 225 million years the Earth, and all the life on it, completes one revolution around the Milky Way Galaxy. During this remarkable journey, life is influenced by calamitous changes. Comets and asteroids strike the surface of the Earth, stars explode, enormous volcanoes erupt, and, more recently, humans litter the planet with waste. Many animals and plants become extinct during the voyage, but humble microbes, simple creatures made of a single cell, survive this journey. This book takes a tour of the microbial world, from the coldest and deepest places on Earth to the hottest and highest, and witnesses some of the most catastrophic events that life can face. Impossible Extinction tells this remarkable story to the general reader by explaining how microbes have survived on Earth for over three billion years. Charles Cockell received his doctorate from the University of Oxford, and is currently a microbiologist with rhe Search for Extraterrestrial Intelligence Institute (SETI), based at the British Antarctic Survey in Cambridge, UK. His research focusses on astrobiology, life in the extremes and the human exploration of Mars. Cockell has been on expeditions to the Arctic, Antarctic, Mongolia, and in 1993 he piloted a modified insect-collecting ultra-light aircraft over the Indonesian rainforests. He is Chair of the Twenty-one Eleven Foundation for Exploration, a charity that supports expeditions that forge links between space exploration and environmentalism.

  17. Seasonal atmospheric extinction

    International Nuclear Information System (INIS)

    Mikhail, J.S.

    1979-01-01

    Mean monochromatic extinction coefficients at various wavelengths at the Kottamia Observatory site have shown the existence of a seasonal variation of atmospheric extinction. The extinction of aerosol compontnts with wavelengths at winter represent exceedingly good conditions. Spring gives the highest extinction due to aerosol. (orig.)

  18. Does poverty alleviation decrease depression symptoms in post-conflict settings? A cluster-randomized trial of microenterprise assistance in Northern Uganda.

    Science.gov (United States)

    Green, E P; Blattman, C; Jamison, J; Annan, J

    2016-01-01

    By 2009, two decades of war and widespread displacement left the majority of the population of Northern Uganda impoverished. This study used a cluster-randomized design to test the hypothesis that a poverty alleviation program would improve economic security and reduce symptoms of depression in a sample of mostly young women. Roughly 120 villages in Northern Uganda were invited to participate. Community committees were asked to identify the most vulnerable women (and some men) to participate. The implementing agency screened all proposed participants, and a total of 1800 were enrolled. Following a baseline survey, villages were randomized to a treatment or wait-list control group. Participants in treatment villages received training, start-up capital, and follow-up support. Participants, implementers, and data collectors were not blinded to treatment status. Villages were randomized to the treatment group (60 villages with 896 participants) or the wait-list control group (60 villages with 904 participants) with an allocation ration of 1:1. All clusters participated in the intervention and were included in the analysis. The intent-to-treat analysis included 860 treatment participants and 866 control participants (4.1% attrition). Sixteen months after the program, monthly cash earnings doubled from UGX 22 523 to 51 124, non-household and non-farm businesses doubled, and cash savings roughly quadrupled. There was no measurable effect on a locally derived measure of symptoms of depression. Despite finding large increases in business, income, and savings among the treatment group, we do not find support for an indirect effect of poverty alleviation on symptoms of depression.

  19. Rationale and study design of a patient-centered intervention to improve health status in chronic heart failure: The Collaborative Care to Alleviate Symptoms and Adjust to Illness (CASA) randomized trial.

    Science.gov (United States)

    Bekelman, David B; Allen, Larry A; Peterson, Jamie; Hattler, Brack; Havranek, Edward P; Fairclough, Diane L; McBryde, Connor F; Meek, Paula M

    2016-11-01

    While contemporary heart failure management has led to some improvements in morbidity and mortality, patients continue to report poor health status (i.e., burdensome symptoms, impaired function, and poor quality of life). The Collaborative Care to Alleviate Symptoms and Adjust to Illness (CASA) trial is a NIH-funded, three-site, randomized clinical trial that examines the effect of the CASA intervention compared to usual care on the primary outcome of patient-reported health status at 6months in patients with heart failure and poor health status. The CASA intervention involves a nurse who works with patients to treat symptoms (e.g., shortness of breath, fatigue, pain) using disease-specific and palliative approaches, and a social worker who provides psychosocial care targeting depression and adjustment to illness. The intervention uses a collaborative care team model of health care delivery and is structured and primarily phone-based to enhance reproducibility and scalability. This article describes the rationale and design of the CASA trial, including several decision points: (1) how to design a patient-centered intervention to improve health status; (2) how to structure the intervention so that it is reproducible and scalable; and (3) how to systematically identify outpatients with heart failure most likely to need and benefit from the intervention. The results should provide valuable information to providers and health systems about the use of team care to manage symptoms and provide psychosocial care in chronic illness. Published by Elsevier Inc.

  20. Effects of overtraining on extinction in newts (Cynops pyrrhogaster)

    OpenAIRE

    Shibasaki, Masahiro; Ishida, Masato

    2012-01-01

    The overtraining extinction effect (OEE), a phenomenon in which extended training facilitates extinction, has been found in mammals and reptiles. However, fish have never shown OEE. No study has yet investigated OEE in newts, a representative amphibian species. We tested whether newts, Cynops pyrrhogaster, show OEE in a straight-array task. All animals received five trials per day and were given a piece of dried worm during reinforced trials. They showed significant acquisition and extinction...

  1. Nature and causes of the immediate extinction deficit: a brief review.

    Science.gov (United States)

    Maren, Stephen

    2014-09-01

    Recent data in both rodents and humans suggests that the timing of extinction trials after conditioning influences the magnitude and duration of extinction. For example, administering extinction trials soon after Pavlovian fear conditioning in rats, mice, and humans results in minimal fear suppression - the so-called immediate extinction deficit. Here I review recent work examining the behavioral and neural substrates of the immediate extinction deficit. I suggest that extinction is most effective at some delay after conditioning, because brain systems involved in encoding and retrieving extinction memories function sub-optimally under stress. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Acute Garcinia mangostana (mangosteen) supplementation does not alleviate physical fatigue during exercise: a randomized, double-blind, placebo-controlled, crossover trial.

    Science.gov (United States)

    Chang, Chih-Wei; Huang, Tzu-Zung; Chang, Wen-Hsin; Tseng, Yi-Chun; Wu, Yu-Tse; Hsu, Mei-Chich

    2016-01-01

    The purple mangosteen (Garcinia mangostana), known as the "queen of fruit," is widely consumed and unique not only because of its outstanding appearance and flavor but also its remarkable and diverse pharmacological effects. The aim of the present study is to evaluate the effect of acute mangosteen supplementation on physical fatigue during exercise. A randomized, double-blind, placebo-controlled, crossover study was carried out by 12 healthy adults. The participants were randomly assigned to receive acute oral administration of either 250 mL of the mangosteen-based juice (supplementation treatment; 305 mg of α-mangostin and 278 mg of hydroxycitric acid) or a placebo (control treatment) 1 h before cycle ergometer exercise. Time to exhaustion, heart rate, Borg Rating of Perceived Exertion score, blood biochemical markers (namely ammonia, cortisol, creatine kinase, aspartate aminotransferase, alanine aminotransferase, glucose, and lactate), muscle dynamic stiffness, and Profile of Mood States (POMS) were evaluated and recorded. The results showed all parameters we examined were significantly altered by the exercise challenge, which demonstrated they directly reflected the condition of fatigue. However, there were no differences between the two treatments besides a positive impact on the POMS examination. The occurrence of physical fatigue depends on multiple underlying mechanisms. We concluded that acute mangosteen supplementation had no impact on alleviating physical fatigue during exercise.

  3. Temporal factors in the extinction of fear in inbred mouse strains differing in extinction efficacy.

    Science.gov (United States)

    MacPherson, Kathryn; Whittle, Nigel; Camp, Marguerite; Gunduz-Cinar, Ozge; Singewald, Nicolas; Holmes, Andrew

    2013-07-05

    Various neuropsychiatric conditions, including posttraumatic stress disorder (PTSD), are characterized by deficient fear extinction, but individuals differ greatly in risk for these. While there is growing evidence that fear extinction is influenced by certain procedural variables, it is unclear how these influences might vary across individuals and subpopulations. To model individual differences in fear extinction, prior studies identified a strain of inbred mouse, 129S1/SvImJ (S1), which exhibits a profound deficit in fear extinction, as compared to other inbred strains, such as C57BL/6J (B6). Here, we assessed the effects of procedural variables on the impaired extinction phenotype of the S1 strain and, by comparison, the extinction-intact B6 strain. The variables studied were 1) the interval between conditioning and extinction, 2) the interval between cues during extinction training, 3) single-cue exposure before extinction training, and 4) extinction of a second-order conditioned cue. Conducting extinction training soon after ('immediately') conditioning attenuated fear retrieval in S1 mice and impaired extinction in B6 mice. Spacing cue presentations with long inter-trial intervals during extinction training augmented fear in S1 and B6 mice. The effect of spacing was lost with one-trial fear conditioning in B6, but not S1 mice. A single exposure to a conditioned cue before extinction training did not alter extinction retrieval, either in B6 or S1 mice. Both the S1 and B6 strains exhibited robust second-order fear conditioning, in which a cue associated with footshock was sufficient to serve as a conditioned exciter to condition a fear association to a second cue. B6 mice extinguished the fear response to the second-order conditioned cue, but S1 mice failed to do so. These data provide further evidence that fear extinction is strongly influenced by multiple procedural variables and is so in a highly strain-dependent manner. This suggests that the efficacy of

  4. Modeling galactic extinction

    OpenAIRE

    Cecchi-Pestellini, C.; Mulas, G.; Casu, S.; Iatì, M. A.; Saija, R.; Cacciola, A.; Borghese, F.; Denti, P.

    2011-01-01

    We present a model for interstellar extinction dust, in which we assume a bimodal distribution of extinction carriers, a dispersion of core-mantle grains, supplemented by a collection of PAHs in free molecular form. We use state-of-the-art methods to calculate the extinction due to macroscopic dust particles, and the absorption cross-sections of PAHs in four different charge states. While successfull for most of observed Galactic extinction curves, in few cases the model cannot provide reliab...

  5. Modern examples of extinctions

    DEFF Research Database (Denmark)

    Lövei, Gabor L

    2013-01-01

    No species lives forever, and extinction is the ultimate fate of all living species. The fossil record indicates that a recent extinction wave affecting terrestrial vertebrates was parallel with the arrival of modern humans to areas formerly uninhabited by them. These modern instances of extinction...

  6. Efficacy and safety of oral ketamine versus diclofenac to alleviate mild to moderate depression in chronic pain patients: A double-blind, randomized, controlled trial.

    Science.gov (United States)

    Jafarinia, Morteza; Afarideh, Mohsen; Tafakhori, Abbas; Arbabi, Mohammad; Ghajar, Alireza; Noorbala, Ahmad Ali; Saravi, Maryam Alamdar; Agah, Elmira; Akhondzadeh, Shahin

    2016-11-01

    Ketamine is a glutamate N-methyl-d-aspartate receptor antagonist capable of exerting antidepressive effects in single or repeated intravenous infusions. The objective of this study was to investigate the safety and the efficacy of oral ketamine vs. diclofenac monotherapy in reducing symptoms of mild to moderate depression among patients with chronic pain. This study is a 6-week, randomized, double-blind, controlled, parallel-group trial with two intervention arms (ketamine, fixed daily dosage of 150mg vs. diclofenac, fixed daily dosage of 150mg). Twenty participants in each arm completed the trial program all of whom had two post-baseline measurements at week 3 and week 6. Reduction in depression symptoms was assessed using the Hamilton Depression Rating Scale (HDRS) and the hospital anxiety and depression subscale for depression (HADSDepression) scores at baseline and week 3 and week 6 post-intervention. Significantly lower HDRS scores were observed in the ketamine treatment group as early as 6 weeks post-intervention (P=0.008). By comparison, mean (±standard deviation) HADS depression subscale scores were significantly lower for individuals receiving ketamine compared to diclofenac for both post-baseline measures at week 3 (6.95±1.47 vs. 8.40±1.6, P=0.005) and week 6 (6.20±1.15 vs. 7.35±1.18, p=0.003). The limitations of the present study were its small sample size and the short-term follow-up period. Oral ketamine appears to be a safe and effective option in improving depressive symptoms of patients with chronic pain with mild-to-moderate depression. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. A Randomized, Double-Blind, Placebo-Controlled Trial: The Efficacy of Multispecies Probiotic Supplementation in Alleviating Symptoms of Irritable Bowel Syndrome Associated with Constipation

    Directory of Open Access Journals (Sweden)

    Valerio Mezzasalma

    2016-01-01

    Full Text Available Background and Aim. The efficacy of supplementation treatment with two multispecies probiotic formulates on subjects diagnosed with IBS-C and the assessment of their gut microbiota were investigated. Methods. A randomized, double-blind, three-arm parallel group trial was carried out on 150 IBS-C subjects divided into three groups (F_1, F_2, and F_3. Each group received a daily oral administration of probiotic mixtures (for 60 days F_1 or F_2 or placebo F_3, respectively. Fecal microbiological analyses were performed by species-specific qPCR to assess the different amount of probiotics. Results. The percentage of responders for each symptom was higher in the probiotic groups when compared to placebo group during the treatment period (t60 and was maintained quite similar during the follow-up period (t90. Fecal analysis demonstrated that probiotics of the formulations increased during the times of treatment only in fecal DNA from subjects treated with F_1 and F_2 and not with F_3, and the same level was maintained during the follow-up period. Conclusions. Multispecies probiotic supplementations are effective in IBS-C subjects and induce a different assessment in the composition of intestinal microbiota. This clinical study is registered with the clinical study registration number ISRCTN15032219.

  8. Bimodal extinction without cross-modal extinction.

    OpenAIRE

    Inhoff, A W; Rafal, R D; Posner, M J

    1992-01-01

    Three patients with unilateral neurological injury were clinically examined. All showed consistent unilateral extinction in the tactile and visual modalities on simultaneous intramodal stimulation. There was virtually no evidence for cross-modal extinction, however, so that contralateral stimulation of one modality would have extinguished perception of ipsilateral stimuli in the other modality. It is concluded that the attentional system controlling the encoding of tactile and visual stimuli ...

  9. Effects of overtraining on extinction in newts (Cynops pyrrhogaster).

    Science.gov (United States)

    Shibasaki, Masahiro; Ishida, Masato

    2012-11-01

    The overtraining extinction effect (OEE), a phenomenon in which extended training facilitates extinction, has been found in mammals and reptiles. However, fish have never shown OEE. No study has yet investigated OEE in newts, a representative amphibian species. We tested whether newts, Cynops pyrrhogaster, show OEE in a straight-array task. All animals received five trials per day and were given a piece of dried worm during reinforced trials. They showed significant acquisition and extinction effects in reinforced and nonreinforced trials. However, we found no difference in extinction performance between a group with 25-trial acquisition and one with 75-trial acquisition, suggesting that OEE was not found in newts. OEE has generally been explained in terms of frustration-related mechanisms. Our results suggest that emotional reactions to nonreward, such as frustration, may not influence behavior in amphibians.

  10. Extinction with multiple excitors

    OpenAIRE

    McConnell, Bridget L.; Miguez, Gonzalo; Miller, Ralph R.

    2013-01-01

    Four conditioned suppression experiments with rats, using an ABC renewal design, investigated the effects of compounding the target conditioned excitor with additional, nontarget conditioned excitors during extinction. Experiment 1 showed stronger extinction, as evidenced by less renewal, when the target excitor was extinguished in compound with a second excitor, relative to when it was extinguished with associatively neutral stimuli. Critically, this deepened extinction effect was attenuated...

  11. End Ordovician extinctions

    DEFF Research Database (Denmark)

    Harper, David A. T.; Hammarlund, Emma; Rasmussen, Christian M. Ø.

    2014-01-01

    -global anoxia associated with a marked transgression during the Late Hirnantian. Most recently, however, new drivers for the extinctions have been proposed, including widespread euxinia together with habitat destruction caused by plate tectonic movements, suggesting that the end Ordovician mass extinctions were...

  12. Extinction of NGC 7027

    International Nuclear Information System (INIS)

    Seaton, M.J.

    1979-01-01

    Emission intensities of recombination lines in hydrogenic spectra are known accurately relative to intensities in the free-free radio continuum. For NGC 7027 intensities have been measured for the radio continuum and for H I and He II lines in the wavelength range from lambda = 2.17 μm to lambda = 1640 A: comparison with the calculated emission intensities gives the extinction. Determinations of the standard interstellar extinction function are critically discussed. The extinction deduced for the total radiation from NGC 7027 has a dependence on wavelength for 6563 A >= lambda >= 1640 A which is in excellent agreement with the adopted standard results, but there are some anomalies for longer wavelengths and for the ratio of total to selective extinction. These can be explained using a model which allows for a local contribution to the extinction which is variable over the surface of the nebula. (author)

  13. Interstellar extinction correlations

    International Nuclear Information System (INIS)

    Jones, A.P.; Williams, D.A.; Duley, W.W.

    1987-01-01

    A recently proposed model for interstellar grains in which the extinction arises from small silicate cores with mantles of hydrogenated amorphous carbon (HAC or α-C:H), and large, but thinly coated, silicate grains can successfully explain many of the observed properties of interstellar dust. The small silicate cores give rise to the 2200 A extinction feature. The extinction in the visual is produced by the large silicates and the HAC mantles on the small cores, whilst the far UV extinction arises in the HAC mantles with a small contribution form the silicate grains. The grain model requires that the silicate material is the more resilient component and that variations in the observed extinction from region to region are due to the nature and depletion of the carbon in the HAC mantles. (author)

  14. Extinction and the fossil record

    Science.gov (United States)

    Sepkoski, J. J. Jr; Sepkoski JJ, ,. J. r. (Principal Investigator)

    1994-01-01

    The author examines evidence of mass extinctions in the fossil record and searches for reasons for such large extinctions. Five major mass extinctions eliminated at least 40 percent of animal genera in the oceans and from 65 to 95 percent of ocean species. Questions include the occurrence of gradual or catastrophic extinctions, causes, environment, the capacity of a perturbation to cause extinctions each time it happens, and the possibility and identification of complex events leading to a mass extinction.

  15. Memory Retrieval before or after Extinction Reduces Recovery of Fear in Adolescent Rats

    Science.gov (United States)

    Baker, Kathryn D.; McNally, Gavan P.; Richardson, Rick

    2013-01-01

    Adolescent rats exhibit impaired extinction retention compared to pre-adolescent and adult rats. A single nonreinforced exposure to the conditioned stimulus (CS; a retrieval trial) given shortly before extinction has been shown in some circumstances to reduce the recovery of fear after extinction in adult animals. This study investigated whether a…

  16. Is IR going extinct?

    Science.gov (United States)

    Mitchell, Audra

    2016-01-01

    A global extinction crisis may threaten the survival of most existing life forms. Influential discourses of ‘existential risk’ suggest that human extinction is a real possibility, while several decades of evidence from conservation biology suggests that the Earth may be entering a ‘sixth mass extinction event’. These conditions threaten the possibilities of survival and security that are central to most branches of International Relations. However, this discipline lacks a framework for addressing (mass) extinction. From notions of ‘nuclear winter’ and ‘omnicide’ to contemporary discourses on catastrophe, International Relations thinking has treated extinction as a superlative of death. This is a profound category mistake: extinction needs to be understood not in the ontic terms of life and death, but rather in the ontological context of be(com)ing and negation. Drawing on the work of theorists of the ‘inhuman’ such as Quentin Meillassoux, Claire Colebrook, Ray Brassier, Jean-Francois Lyotard and Nigel Clark, this article provides a pathway for thinking beyond existing horizons of survival and imagines a profound transformation of International Relations. Specifically, it outlines a mode of cosmopolitics that responds to the element of the inhuman and the forces of extinction. Rather than capitulating to narratives of tragedy, this cosmopolitics would make it possible to think beyond the restrictions of existing norms of ‘humanity’ to embrace an ethics of gratitude and to welcome the possibility of new worlds, even in the face of finitude.

  17. Temporal Dynamics of Recovery from Extinction Shortly after Extinction Acquisition

    Science.gov (United States)

    Archbold, Georgina E.; Dobbek, Nick; Nader, Karim

    2013-01-01

    Evidence suggests that extinction is new learning. Memory acquisition involves both short-term memory (STM) and long-term memory (LTM) components; however, few studies have examined early phases of extinction retention. Retention of auditory fear extinction was examined at various time points. Shortly (1-4 h) after extinction acquisition…

  18. Stress and Fear Extinction

    Science.gov (United States)

    Maren, Stephen; Holmes, Andrew

    2016-01-01

    Stress has a critical role in the development and expression of many psychiatric disorders, and is a defining feature of posttraumatic stress disorder (PTSD). Stress also limits the efficacy of behavioral therapies aimed at limiting pathological fear, such as exposure therapy. Here we examine emerging evidence that stress impairs recovery from trauma by impairing fear extinction, a form of learning thought to underlie the suppression of trauma-related fear memories. We describe the major structural and functional abnormalities in brain regions that are particularly vulnerable to stress, including the amygdala, prefrontal cortex, and hippocampus, which may underlie stress-induced impairments in extinction. We also discuss some of the stress-induced neurochemical and molecular alterations in these brain regions that are associated with extinction deficits, and the potential for targeting these changes to prevent or reverse impaired extinction. A better understanding of the neurobiological basis of stress effects on extinction promises to yield novel approaches to improving therapeutic outcomes for PTSD and other anxiety and trauma-related disorders. PMID:26105142

  19. Analgecine, the extracts of Vaccinia-inoculated rabbit skin, effectively alleviates the chronic low back pain with little side effect – A randomized multi-center double-blind placebo-controlled phase 3 clinical trial

    Directory of Open Access Journals (Sweden)

    Jian Dong

    2016-04-01

    Conclusion: Analgecine (AGC, 8 units twice daily effectively alleviates chronic low back pain due to degenerative vertebral disorders when compared to placebo and is well tolerated by tested individuals, and can be considered as a first-line treatment for chronic low pain due to degenerative vertebral diseases.

  20. Acute stress impairs the retrieval of extinction memory in humans

    Science.gov (United States)

    Raio, Candace M.; Brignoni-Perez, Edith; Goldman, Rachel; Phelps, Elizabeth A.

    2014-01-01

    Extinction training is a form of inhibitory learning that allows an organism to associate a previously aversive cue with a new, safe outcome. Extinction does not erase a fear association, but instead creates a competing association that may or may not be retrieved when a cue is subsequently encountered. Characterizing the conditions under which extinction learning is expressed is important to enhancing the treatment of anxiety disorders that rely on extinction-based exposure therapy as a primary treatment technique. The ventromedial prefrontal cortex, which plays an important role in the expression of extinction memory, has been shown to be functionally impaired after stress exposure. Further, recent research in rodents found that exposure to stress led to deficits in extinction retrieval, although this has yet to be tested in humans. To explore how stress might influence extinction retrieval in humans, participants underwent a differential aversive learning paradigm, in which one image was probabilistically paired with an aversive shock while the other image denoted safety. Extinction training directly followed, at which point reinforcement was omitted. A day later, participants returned to the lab and either completed an acute stress manipulation (i.e., cold pressor), or a control task, before undergoing an extinction retrieval test. Skin conductance responses and salivary cortisol concentrations were measured throughout each session as indices of fear arousal and neuroendocrine stress responses, respectively. The efficacy of our stress induction was established by observing significant increases in cortisol for the stress condition only. We examined extinction retrieval by comparing conditioned responses during the last trial of extinction (day 1) with that of the first trial of re-extinction (day 2). Groups did not differ on initial fear acquisition or extinction, however, one day later participants in the stress group (n = 27) demonstrated significantly less

  1. Biological Extinction in Earth History

    Science.gov (United States)

    Raup, David M.

    1986-03-01

    Virtually all plant and animal species that have ever lived on the earth are extinct. For this reason alone, extinction must play an important role in the evolution of life. The five largest mass extinctions of the past 600 million years are of greatest interest, but there is also a spectrum of smaller events, many of which indicate biological systems in profound stress. Extinction may be episodic at all scales, with relatively long periods of stability alternating with short-lived extinction events. Most extinction episodes are biologically selective, and further analysis of the victims and survivors offers the greatest chance of deducing the proximal causes of extinction. A drop in sea level and climatic change are most frequently invoked to explain mass extinctions, but new theories of collisions with extraterrestrial bodies are gaining favor. Extinction may be constructive in a Darwinian sense or it may only perturb the system by eliminating those organisms that happen to be susceptible to geologically rare stresses.

  2. Biological extinction in earth history

    Science.gov (United States)

    Raup, D. M.

    1986-01-01

    Virtually all plant and animal species that have ever lived on the earth are extinct. For this reason alone, extinction must play an important role in the evolution of life. The five largest mass extinctions of the past 600 million years are of greatest interest, but there is also a spectrum of smaller events, many of which indicate biological systems in profound stress. Extinction may be episodic at all scales, with relatively long periods of stability alternating with short-lived extinction events. Most extinction episodes are biologically selective, and further analysis of the victims and survivors offers the greatest chance of deducing the proximal causes of extinction. A drop in sea level and climatic change are most frequently invoked to explain mass extinctions, but new theories of collisions with extraterrestrial bodies are gaining favor. Extinction may be constructive in a Darwinian sense or it may only perturb the system by eliminating those organisms that happen to be susceptible to geologically rare stresses.

  3. Interstellar dust and extinction

    International Nuclear Information System (INIS)

    Mathis, J.S.

    1990-01-01

    It is noted that the term interstellar dust refers to materials with rather different properties, and that the mean extinction law of Seaton (1979) or Savage and Mathis (1979) should be replaced by the expression given by Cardelli et al. (1989), using the appropriate value of total-to-selective extinction. The older laws were appropriate for the diffuse ISM but dust in clouds differs dramatically in its extinction law. Dust is heavily processed while in the ISM by being included within clouds and cycled back into the diffuse ISM many times during its lifetime. Hence, grains probably reflect only a trace of their origin, although meteoritic inclusions with isotopic anomalies demonstrate that some tiny particles survive intact from a supernova origin to the present. 186 refs

  4. Recovery effects after extinction in the Morris swimming pool navigation task.

    Science.gov (United States)

    Prados, José; Manteiga, Raúl D; Sansa, Joan

    2003-08-01

    In three experiments in which rats were used as subjects, we developed an extinction procedure using a Morris pool. The animals were trained to find a hidden platform located at a fixed position and were then given extinction trials in which the platform was removed from the pool. When training and extinction were carried out in the same context and time was allowed to elapse between extinction and test, spontaneous recovery of learning was observed. On the other hand, those rats that received extinction in a context different from the one used for training failed to show spontaneous recovery of learning when tested in the extinction context after an interval of 96 h. However, they did show renewal of spatial learning when tested in the training context. These results show that extinction in the spatial domain behaves like extinction in standard conditioning preparations.

  5. Extinction of aversive classically conditioned human sexual response.

    Science.gov (United States)

    Brom, Mirte; Laan, Ellen; Everaerd, Walter; Spinhoven, Philip; Both, Stephanie

    2015-04-01

    Research has shown that acquired subjective likes and dislikes are quite resistant to extinction. Moreover, studies on female sexual response demonstrated that diminished genital arousal and positive affect toward erotic stimuli due to aversive classical conditioning did not extinguish during an extinction phase. Possible resistance to extinction of aversive conditioned sexual responses may have important clinical implications. However, resistance to extinction of aversive conditioned human sexual response has not been studied using extensive extinction trials. This article aims to study resistance to extinction of aversive conditioned sexual responses in sexually functional men and women. A differential conditioning experiment was conducted, with two erotic pictures as conditioned stimulus (CSs) and a painful stimulus as unconditioned stimuli (USs). Only one CS (the CS+) was followed by the US during the acquisition phase. Conditioned responses were assessed during the extinction phase. Penile circumference and vaginal pulse amplitude were assessed, and ratings of affective value and subjective sexual arousal were obtained. Also, a stimulus response compatibility task was included to assess automatic approach and avoidance tendencies. Men and women rated the CS+ more negative as compared with the CS-. During the first trials of the extinction phase, vaginal pulse amplitude was lower in response to the CS+ than in response to the CS-, and on the first extinction trial women rated the CS+ as less sexually arousing. Intriguingly, men did not demonstrate attenuated genital and subjective sexual response. Aversive conditioning, by means of painful stimuli, only affects sexual responses in women, whereas it does not in men. Although conditioned sexual likes and dislikes are relatively persistent, conditioned affect eventually does extinguish. © 2014 International Society for Sexual Medicine.

  6. Extinction of sodium fires

    International Nuclear Information System (INIS)

    Malet, J.C.; Spagna, F.

    1989-01-01

    This paper presents how, starting from a knowledge of sodium ignition and burning, principles for extinction (smothering catch trays, leak recuperation systems, powders) can be developed. These techniques applied in Superphenix 1 and PEC reactors have been tested in the ESMERALDA experimental program which is a joint French/Italian project. (author)

  7. Early Extinction after Fear Conditioning Yields a Context-Independent and Short-Term Suppression of Conditional Freezing in Rats

    Science.gov (United States)

    Chang, Chun-hui; Maren, Stephen

    2009-01-01

    Extinction of Pavlovian fear conditioning in rats is a useful model for therapeutic interventions in humans with anxiety disorders. Recently, we found that delivering extinction trials soon (15 min) after fear conditioning yields a short-term suppression of fear, but little long-term extinction. Here, we explored the possible mechanisms underlying…

  8. Metapopulation extinction risk: dispersal's duplicity.

    Science.gov (United States)

    Higgins, Kevin

    2009-09-01

    Metapopulation extinction risk is the probability that all local populations are simultaneously extinct during a fixed time frame. Dispersal may reduce a metapopulation's extinction risk by raising its average per-capita growth rate. By contrast, dispersal may raise a metapopulation's extinction risk by reducing its average population density. Which effect prevails is controlled by habitat fragmentation. Dispersal in mildly fragmented habitat reduces a metapopulation's extinction risk by raising its average per-capita growth rate without causing any appreciable drop in its average population density. By contrast, dispersal in severely fragmented habitat raises a metapopulation's extinction risk because the rise in its average per-capita growth rate is more than offset by the decline in its average population density. The metapopulation model used here shows several other interesting phenomena. Dispersal in sufficiently fragmented habitat reduces a metapopulation's extinction risk to that of a constant environment. Dispersal between habitat fragments reduces a metapopulation's extinction risk insofar as local environments are asynchronous. Grouped dispersal raises the effective habitat fragmentation level. Dispersal search barriers raise metapopulation extinction risk. Nonuniform dispersal may reduce the effective fraction of suitable habitat fragments below the extinction threshold. Nonuniform dispersal may make demographic stochasticity a more potent metapopulation extinction force than environmental stochasticity.

  9. THE SECONDARY EXTINCTION CORRECTION

    Energy Technology Data Exchange (ETDEWEB)

    Zachariasen, W. H.

    1963-03-15

    It is shown that Darwin's formula for the secondary extinction correction, which has been universally accepted and extensively used, contains an appreciable error in the x-ray diffraction case. The correct formula is derived. As a first order correction for secondary extinction, Darwin showed that one should use an effective absorption coefficient mu + gQ where an unpolarized incident beam is presumed. The new derivation shows that the effective absorption coefficient is mu + 2gQ(1 + cos/sup 4/2 theta )/(1 plus or minus cos/sup 2/2 theta )/s up 2/, which gives mu + gQ at theta =0 deg and theta = 90 deg , but mu + 2gQ at theta = 45 deg . Darwin's theory remains valid when applied to neutron diffraction. (auth)

  10. Galactic dust and extinction

    International Nuclear Information System (INIS)

    Lyngaa, G.

    1979-01-01

    The ratio R between visual extinction and colour excess, is slightly larger than 3 and does not vary much throughout our part of the Galaxy. The distribution of dust in the galactic plane shows, on the large scale, a gradient with higher colour excesses towards l=50 0 than towards l=230 0 . On the smaller scale, much of the dust responsible for extinction is situated in clouds which tend to group together. The correlation between positions of interstellar dust clouds and positions of spiral tracers seems rather poor in our Galaxy. However, concentrated dark clouds as well as extended regions of dust show an inclined distribution similar to the Gould belt of bright stars. (Auth.)

  11. Building physiological toughness: Some aversive events during extinction may attenuate return of fear.

    Science.gov (United States)

    Culver, Najwa C; Stevens, Stephan; Fanselow, Michael S; Craske, Michelle G

    2018-03-01

    Although exposure therapy is an effective treatment for anxiety disorders, fear sometimes returns following successful therapy. Recent literature in animal models indicates that incorporating some aversive events into extinction training may offset these return of fear effects. The effect of occasional reinforced extinction trials was investigated in a sample of thirty-nine participants using a fear conditioning and extinction paradigm. Participants either underwent traditional extinction procedures during which the conditional stimulus which had been paired with the unconditional stimulus (US) during acquisition training (CS+) was presented alone with no presentations of the US or partially reinforced extinction during which there were several unpredicted CS+/US pairings. As measured by skin conductance responses, physiological fear responding remained elevated during extinction for participants who experienced partially reinforced extinction; however, these participants demonstrated protection from rapid reacquisition effects. Results from the subjective US-expectancy ratings did not provide evidence of protection against rapid reacquisition in the partially reinforced extinction group; however, there was evidence of protection from spontaneous recovery effects. Lastly, as measured by valence ratings, it was unclear whether partially reinforced extinction provided protection from fear recovery effects. Although participants who experienced partially reinforced extinction demonstrated protection from rapid reacquisition as measured by skin conductance responses, they also demonstrated significantly higher levels of physiological fear responding during extinction which made the results of the spontaneous recovery test more difficult to interpret. Occasional CS-US pairings during extinction may protect against return of fear effects. Clinical implications are discussed. Published by Elsevier Ltd.

  12. Changes in expression of c-Fos protein following cocaine-cue extinction learning.

    Science.gov (United States)

    Nic Dhonnchadha, B Á; Lovascio, B F; Shrestha, N; Lin, A; Leite-Morris, K A; Man, H Y; Kaplan, G B; Kantak, K M

    2012-09-01

    Extinguishing abnormally strengthened learned responses to cues associated with drugs of abuse remains a key tactic for alleviating addiction. To assist in developing pharmacotherapies to augment exposure therapy for relapse prevention, investigation into neurobiological underpinnings of drug-cue extinction learning is needed. We used regional analyses of c-Fos and GluR2 protein expression to delineate neural activity and plasticity that may be associated with cocaine-cue extinction learning. Rats were trained to self-administer cocaine paired with a light cue, and later underwent a single 2h extinction session for which cocaine was withheld but response-contingent cues were presented (cocaine-cue extinction). Control groups consisted of rats yoked to animals self-administering cocaine and receiving saline non-contingently followed by an extinction session, or rats trained to self-administer cocaine followed by a no-extinction session for which levers were retracted, and cocaine and cues were withheld. Among 11 brain sites examined, extinction training increased c-Fos expression in basolateral amygdala and prelimbic prefrontal cortex of cocaine-cue extinguished rats relative to both control conditions. In dorsal subiculum and infralimbic prefrontal cortex, extinction training increased c-Fos expression in both cocaine-cue and saline-cue extinguished rats relative to the no-extinction control condition. GluR2 protein expression was not altered in any site examined after extinction or control training. Findings suggest that basolateral amygdala and prelimbic prefrontal cortex neurons are activated during acquisition of cocaine-cue extinction learning, a process that is independent of changes in GluR2 abundance. Other sites are implicated in processing the significance of cues that are present early in extinction training. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Extinction after fear memory reactivation fails to eliminate renewal in rats.

    Science.gov (United States)

    Goode, Travis D; Holloway-Erickson, Crystal M; Maren, Stephen

    2017-07-01

    Retrieving fear memories just prior to extinction has been reported to effectively erase fear memories and prevent fear relapse. The current study examined whether the type of retrieval procedure influences the ability of extinction to impair fear renewal, a form of relapse in which responding to a conditional stimulus (CS) returns outside of the extinction context. Rats first underwent Pavlovian fear conditioning with an auditory CS and footshock unconditional stimulus (US); freezing behavior served as the index of conditioned fear. Twenty-four hours later, the rats underwent a retrieval-extinction procedure. Specifically, 1h prior to extinction (45 CS-alone trials; 44 for rats receiving a CS reminder), fear memory was retrieved by either a single exposure to the CS alone, the US alone, a CS paired with the US, or exposure to the conditioning context itself. Over the next few days, conditional freezing to the extinguished CS was tested in the extinction and conditioning context in that order (i.e., an ABBA design). In the extinction context, rats that received a CS+US trial before extinction exhibited higher levels of conditional freezing than animals in all other groups, which did not differ from one another. In the renewal context, all groups showed renewal, and none of the reactivation procedures reduced renewal relative to a control group that did not receive a reactivation procedure prior to extinction. These data suggest retrieval-extinction procedures may have limited efficacy in preventing fear renewal. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Modelling interstellar extinction: Pt. 1

    International Nuclear Information System (INIS)

    Jones, A.P.

    1988-01-01

    Several methods of calculating the extinction of porous silicate grains are discussed, these include effective medium theories and hollow spherical shells. Porous silicate grains are shown to produce enhanced infrared, ultraviolet and far-ultraviolet extinction and this effect can be used to reduce the abundance of carbon required to match the average interstellar extinction, however, matching the visual extinction is rather more problematical. We have shown that the enhanced extinction at long and short wavelengths have different origins, and have explained why the visual extinction is little affected by porosity. The implications of porous grains in the interstellar medium are discussed with particular reference to surface chemistry, the polarization of starlight, and their dynamical evolution. (author)

  15. Extinction Events Can Accelerate Evolution

    DEFF Research Database (Denmark)

    Lehman, Joel; Miikkulainen, Risto

    2015-01-01

    Extinction events impact the trajectory of biological evolution significantly. They are often viewed as upheavals to the evolutionary process. In contrast, this paper supports the hypothesis that although they are unpredictably destructive, extinction events may in the long term accelerate...... evolution by increasing evolvability. In particular, if extinction events extinguish indiscriminately many ways of life, indirectly they may select for the ability to expand rapidly through vacated niches. Lineages with such an ability are more likely to persist through multiple extinctions. Lending...... computational support for this hypothesis, this paper shows how increased evolvability will result from simulated extinction events in two computational models of evolved behavior. The conclusion is that although they are destructive in the short term, extinction events may make evolution more prolific...

  16. Rescuing Ecosystems from Extinction Cascades

    Science.gov (United States)

    Sahasrabudhe, Sagar; Motter, Adilson

    2010-03-01

    Food web perturbations stemming from climate change, overexploitation, invasive species, and natural disasters often cause an initial loss of species that results in a cascade of secondary extinctions. Using a predictive modeling framework, here we will present a systematic network-based approach to reduce the number of secondary extinctions. We will show that the extinction of one species can often be compensated by the concurrent removal of a second specific species, which is a counter-intuitive effect not previously tested in complex food webs. These compensatory perturbations frequently involve long-range interactions that are not a priori evident from local predator-prey relationships. Strikingly, in numerous cases even the early removal of a species that would eventually be extinct by the cascade is found to significantly reduce the number of cascading extinctions. Other nondestructive interventions based on partial removals and growth suppression and/or mortality increase are shown to sometimes prevent all secondary extinctions.

  17. Acoustic integrated extinction

    OpenAIRE

    Norris, Andrew N.

    2015-01-01

    The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122, 3206–3210. (doi:10.1121/1.2801546)) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we der...

  18. Mass extinctions of Earth

    International Nuclear Information System (INIS)

    Fernandez, B.; Fernandez, P.; Pereira, B.

    2015-01-01

    Throughout the history of our planet, there have been global phenomena which have led to the disappearance of a large number of species: It is what is known as mass or massive extinctions. This article will make a tour of these large events, from the most remote antiquity to the present day. Today we find ourselves immersed in a process unprecedented since we are eyewitnesses and, more important still, an active part in the decision-making process to try to mitigate their effects. (Author)

  19. Mass extinctions and supernova explosions

    OpenAIRE

    Korschinek, Gunther

    2016-01-01

    A nearby supernova (SN) explosion could have negatively influenced life on Earth, maybe even been responsible for mass extinctions. Mass extinction poses a significant extinction of numerous species on Earth, as recorded in the paleontologic, paleoclimatic, and geological record of our planet. Depending on the distance between the Sun and the SN, different types of threats have to be considered, such as ozone depletion on Earth, causing increased exposure to the Sun's ultraviolet radiation, o...

  20. Alleviating energy poverty: Indian experience

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Garima

    2010-09-15

    Energy services play an important role in human welfare. India faces acute energy poverty indicating lack of access of clean energy fuels. Access to electricity is limited to 56% households in India and about 89% of rural households depend on polluting energy sources. Energy poverty impacts income poverty as poor find it difficult to acquire high priced cleaner fuels. It also adversely impacts the socio economic conditions of women. The paper highlights the linkage of energy poverty with income poverty and gender inequality. It analyses measures taken to alleviate energy poverty and recommends regulatory and policy measures as way forward.

  1. Extinction of H II regions

    International Nuclear Information System (INIS)

    Israel, F.P.; Kennicutt, R.C.

    1980-01-01

    Visual extinction of H II regions in nine nearby galaxies as derived from the ratio of the radio continuum emission to H-alpha emission is systematically larger than visual extinction deduced from the Balmer lines alone, if one assumes a value Av/E(B-V) 3. An optically-limited sample of about 30 extragalactic H II regions has a mean extinction of 1.7 m in the visual while about 1.2 m is not seen in the reddening of the Balmer lines. Both reddening and extinction decreases with increasing galactic radius, at least for M33 and M101

  2. A reconciliation of extinction theories

    International Nuclear Information System (INIS)

    Sabine, T.M.

    1988-01-01

    The differences between previous theoretical treatments of extinction based on the Darwin intensity equations arise because of the different functional form chosen for the coupling constant σ. When the same function is used these theories make closely similar predictions. It is shown that a limiting condition on integrated intensity as the crystal size increases puts restrictions on the functions which may be used. A Lorentzian or Fresnellian function can be used for primary extinction while secondary extinction requires a Gaussian, rectangular or triangular function. An analytical expression is given for the variation in the value of the extinction factor with scattering angle. (orig.)

  3. The effect of hippocampal NMDA receptor blockade by MK-801 on cued fear extinction.

    Science.gov (United States)

    Zhang, Bo; Li, Chuan-Yu; Wang, Xiu-Song

    2017-08-14

    Extinction of conditioned fear has been suggested to be a new form of learning instead of erasure of what was originally learned, and the process is NMDA (N-methyl d-aspartate) receptor (NMDAR) dependent. Most of studies have so far revealed the important roles of NMDARs in the amygdala and medial prefrontal cortex (mPFC) in cued fear extinction. Although the ventral hippocampus has intimately reciprocal connections with the amygdala and mPFC, the role of its NMDARs in cued fear extinction remains unclear. The present experiment explored the issue by bilateral pre-extinction microinjection of the noncompetitive NMDAR antagonist MK-801 into the ventral hippocampus. Four groups of rats were given habituation, tone cued fear conditioning, fear extinction training and extinction test. Prior to extinction training, rats received bilateral infusions of either MK-801 (1.5, 3, or 6μg/0.5μl) or saline. Our results showed that MK-801 reduced freezing on the first trial of extinction training with no impact on within-session acquisition of extinction, and that the lower doses of MK-801 resulted in increased freezing on the extinction retrieval test. These findings suggest that ventral hippocampal NMDARs are necessary for the consolidation of tone cued fear extinction. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. THE MEMORY SYSTEM ENGAGED DURING ACQUISITION DETERMINES THE EFFECTIVENESS OF DIFFERENT EXTINCTION PROTOCOLS

    Directory of Open Access Journals (Sweden)

    Jarid eGoodman

    2015-11-01

    effectiveness of latent extinction may depend on the type of memory being extinguished. The findings suggest that behavioral treatments modeled after response extinction protocols may be especially useful in alleviating human psychopathologies involving striatum-dependent memory processes (i.e. drug addiction and relapse.

  5. Global extinction in spiral galaxies

    NARCIS (Netherlands)

    Tully, RB; Pierce, MJ; Saunders, W; Verheijen, MAW; Witchalls, PL

    Magnitude-limited samples of spiral galaxies drawn from the Ursa Major and Pisces Clusters are used to determine their extinction properties as a function of inclination. Imaging photometry is available for 87 spirals in the B, R, I, and K' bands. Extinction causes systematic scatter in

  6. Evolution: Postponing Extinction by Polyandry

    OpenAIRE

    Wade, Michael J.

    2010-01-01

    Sex-ratio meiotic drive occurs when males produce a predominance of X-chromosome bearing sperm and an inordinate number of daughters. A driving X causes highly female-biased sex ratios and the risk of extinction. Polyandry can rescue a population from extinction.

  7. Optimising Extinction of Conditioned Disgust

    NARCIS (Netherlands)

    Bosman, Renske C.; Borg, Charmaine; de Jong, Peter J.

    2016-01-01

    Maladaptive disgust responses are tenacious and resistant to exposure-based interventions. In a similar vein, laboratory studies have shown that conditioned disgust is relatively insensitive to Conditioned Stimulus (CS)-only extinction procedures. The relatively strong resistance to extinction might

  8. Behavioral tagging of extinction learning.

    Science.gov (United States)

    de Carvalho Myskiw, Jociane; Benetti, Fernando; Izquierdo, Iván

    2013-01-15

    Extinction of contextual fear in rats is enhanced by exposure to a novel environment at 1-2 h before or 1 h after extinction training. This effect is antagonized by administration of protein synthesis inhibitors anisomycin and rapamycin into the hippocampus, but not into the amygdala, immediately after either novelty or extinction training, as well as by the gene expression blocker 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole administered after novelty training, but not after extinction training. Thus, this effect can be attributed to a mechanism similar to synaptic tagging, through which long-term potentiation can be enhanced by other long-term potentiations or by exposure to a novel environment in a protein synthesis-dependent fashion. Extinction learning produces a tag at the appropriate synapses, whereas novelty learning causes the synthesis of plasticity-related proteins that are captured by the tag, strengthening the synapses that generated this tag.

  9. Extinction of Harrington's mountain goat

    International Nuclear Information System (INIS)

    Mead, J.I.; Martin, P.S.; Euler, R.C.; Long, A.; Jull, A.J.T.; Toolin, L.J.; Donahue, D.J.; Linick, T.W.

    1986-01-01

    Keratinous horn sheaths of the extinct Harrington's mountain goat, Oreamnos harringtoni, were recovered at or near the surface of dry caves of the Grand Canyon, Arizona. Twenty-three separate specimens from two caves were dated nondestructively by the tandem accelerator mass spectrometer (TAMS). Both the TAMS and the conventional dates indicate that Harrington's mountain goat occupied the Grand Canyon for at least 19,000 years prior to becoming extinct by 11,160 +/- 125 radiocarbon years before present. The youngest average radiocarbon dates on Shasta ground sloths, Nothrotheriops shastensis, from the region are not significantly younger than those on extinct mountain goats. Rather than sequential extinction with Harrington's mountain goat disappearing from the Grand Canyon before the ground sloths, as one might predict in view of evidence of climatic warming at the time, the losses were concurrent. Both extinctions coincide with the regional arrival of Clovis hunters

  10. Extinction of metal fires

    International Nuclear Information System (INIS)

    Mellottee, H.

    1977-01-01

    The main points of a large bibliography on liquid and solid metal fires are set out. The various methods used to fight these fires are presented; covering by powders is specially emphasized. Since this method has promising results, the various possible techniques, extinction by cooling the metal, by blanketing, by formation of a continuous insulating layer (by fusion or pyrolysis of a powder) or by a surface reaction between powder and metal are studied. The conditions of conservation and use of powders are outlined, then the various powders are described: inert powders, powders undergoing a physical transformation (fusion or vitrification of an organic compound, fusion of eutectic inorganic mixtures), multiple effect powders. Precise examples are quoted [fr

  11. Activation of orexin/hypocretin neurons is associated with individual differences in cued fear extinction.

    Science.gov (United States)

    Sharko, Amanda C; Fadel, Jim R; Kaigler, Kris F; Wilson, Marlene A

    2017-09-01

    Identifying the neurobiological mechanisms that underlie differential sensitivity to stress is critical for understanding the development and expression of stress-induced disorders, such as post-traumatic stress disorder (PTSD). Preclinical studies have suggested that rodents display different phenotypes associated with extinction of Pavlovian conditioned fear responses, with some rodent populations being resistant to extinction. An emerging literature also suggests a role for orexins in the consolidation processes associated with fear learning and extinction. To examine the possibility that the orexin system might be involved in individual differences in fear extinction, we used a Pavlovian conditioning paradigm in outbred Long-Evans rats. Rats showed significant variability in the extinction of cue-conditioned freezing and extinction recall, and animals were divided into groups based on their extinction profiles based on a median split of percent freezing behavior during repeated exposure to the conditioned cue. Animals resistant to extinction (high freezers) showed more freezing during repeated cue presentations during the within trial and between trial extinction sessions compared with the group showing significant extinction (low freezers), although there were no differences between these groups in freezing upon return to the conditioned context or during the conditioning session. Following the extinction recall session, activation of orexin neurons was determined using dual label immunohistochemistry for cFos in orexin positive neurons in the hypothalamus. Individual differences in the extinction of cue conditioned fear were associated with differential activation of hypothalamic orexin neurons. Animals showing poor extinction of cue-induced freezing (high freezers) had significantly greater percentage of orexin neurons with Fos in the medial hypothalamus than animals displaying significant extinction and good extinction recall (low freezers). Further, the

  12. Measuring Extinction with ALE

    Science.gov (United States)

    Zimmer, Peter C.; McGraw, J. T.; Gimmestad, G. G.; Roberts, D.; Stewart, J.; Smith, J.; Fitch, J.

    2007-12-01

    ALE (Astronomical LIDAR for Extinction) is deployed at the University of New Mexico's (UNM) Campus Observatory in Albuquerque, NM. It has begun a year-long testing phase prior deployment at McDonald Observatory in support of the CCD/Transit Instrument II (CTI-II). ALE is designed to produce a high-precision measurement of atmospheric absorption and scattering above the observatory site every ten minutes of every moderately clear night. LIDAR (LIght Detection And Ranging) is the VIS/UV/IR analog of radar, using a laser, telescope and time-gated photodetector instead of a radio transmitter, dish and receiver. In the case of ALE -- an elastic backscatter LIDAR -- 20ns-long, eye-safe laser pulses are launched 2500 times per second from a 0.32m transmitting telescope co-mounted with a 50mm short-range receiver on an alt-az mounted 0.67m long-range receiver. Photons from the laser pulse are scattered and absorbed as the pulse propagates through the atmosphere, a portion of which are scattered into the field of view of the short- and long-range receiver telescopes and detected by a photomultiplier. The properties of a given volume of atmosphere along the LIDAR path are inferred from both the altitude-resolved backscatter signal as well as the attenuation of backscatter signal from altitudes above it. We present ALE profiles from the commissioning phase and demonstrate some of the astronomically interesting atmospheric information that can be gleaned from these data, including, but not limited to, total line-of-sight extinction. This project is funded by NSF Grant 0421087.

  13. Systemic propranolol acts centrally to reduce conditioned fear in rats without impairing extinction.

    Science.gov (United States)

    Rodriguez-Romaguera, Jose; Sotres-Bayon, Francisco; Mueller, Devin; Quirk, Gregory J

    2009-05-15

    Previous work has implicated noradrenergic beta-receptors in the consolidation and reconsolidation of conditioned fear. Less is known, however, about their role in fear expression and extinction. The beta-receptor blocker propranolol has been used clinically to reduce anxiety. With an auditory fear conditioning task in rats, we assessed the effects of systemic propranolol on the expression and extinction of two measures of conditioned fear: freezing and suppression of bar-pressing. One day after receiving auditory fear conditioning, rats were injected with saline, propranolol, or peripheral beta-receptor blocker sotalol (both 10 mg/kg, IP). Twenty minutes after injection, rats were given either 6 or 12 extinction trials and were tested for extinction retention the following day. The effect of propranolol on the firing rate of neurons in prelimbic (PL) prefrontal cortex was also assessed. Propranolol reduced freezing by more than 50%, an effect that was evident from the first extinction trial. Suppression was also significantly reduced. Despite this, propranolol had no effect on the acquisition or retention of extinction. Unlike propranolol, sotalol did not affect fear expression, although both drugs significantly reduced heart rate. This suggests that propranolol acts centrally to reduce fear. Consistent with this, propranolol reduced the firing rate of PL neurons. Propranolol reduced the expression of conditioned fear, without interfering with extinction learning. Reduced fear with intact extinction suggests a possible use for propranolol in reducing anxiety during extinction-based exposure therapies, without interfering with long-term clinical response.

  14. Education as a tool for addressing the extinction crisis: moving students from understanding to action.

    Science.gov (United States)

    Moyer-Horner, Lucas; Kirby, Rebecca; Vaughan, Christopher

    2010-12-01

    Human activity is leading to mass species extinctions worldwide. Conservation biology (CB) courses, taught worldwide at universities, typically focus on the proximal causes of extinction without teaching students how to respond to this crisis. The Extinction of Species 360 course has been taught yearly each fall semester to several hundred students at the University of Wisconsin-Madison for over two decades. In 2007 the instructor and five teaching assistants combined principles driving extinctions, based on traditional lectures and discussion sections, with action-oriented education targeting individual consumer habits, to a group of 285 students. Students learn the science underpinning conservation efforts, as evidenced by highly significant learning (crisis and c) facilitated activities to reduce our impact and help alleviate the crisis. The results suggested students learned CB concepts and understood biodiversity's value, increased their awareness of the connection between personal consumption and extinction, and reduced their collective ecological footprints. Furthermore, students complemented their learning and multiplied the potential for consumption reduction, by participating in action-based activities. Such academic courses can provide a rigorous treatment of the direct and indirect causes of extinction while developing a student's sense of personal empowerment to help slow the extinction crisis.

  15. Spontaneous Recovery After Extinction of the Conditioned Proboscis Extension Response in the Honeybee

    Science.gov (United States)

    Sandoz, Jean-Christophe; Pham-Delègue, Minh-Hà

    2004-01-01

    In honeybees, the proboscis extension response (PER) can be conditioned by associating an odor stimulus (CS) to a sucrose reward (US). Conditioned responses to the CS, which are acquired by most bees after a single CS-US pairing, disappear after repeated unrewarded presentations of the CS, a process called extinction. Extinction is usually thought to be based either on (1) the disruption of the stored CS-US association, or (2) the formation of an inhibitory “CS-no US” association that is better retrieved than the initial CS-US association. The observation of spontaneous recovery, i.e., the reappearance of responses to the CS after time passes following extinction, is traditionally interpreted as a proof for the formation of a transient inhibitory association. To provide a better understanding of extinction in honeybees, we examined whether time intervals during training and extinction or the number of conditioning and extinction trials have an effect on the occurrence of spontaneous recovery. We found that spontaneous recovery mostly occurs when conditioning and testing took place in a massed fashion (1-min intertrial intervals). Moreover, spontaneous recovery depended on the time elapsed since extinction, 1 h being an optimum. Increasing the number of conditioning trials improved the spontaneous recovery level, whereas increasing the number of extinction trials reduced it. Lastly, we show that after single-trial conditioning, spontaneous recovery appears only once after extinction. These elements suggest that in honeybees extinction of the PER actually reflects the impairment of the CS-US association, but that depending on training parameters different memory substrates are affected. PMID:15466313

  16. Genetic sex determination and extinction.

    Science.gov (United States)

    Hedrick, Philip W; Gadau, Jürgen; Page, Robert E

    2006-02-01

    Genetic factors can affect the probability of extinction either by increasing the effect of detrimental variants or by decreasing the potential for future adaptive responses. In a recent paper, Zayed and Packer demonstrate that low variation at a specific locus, the complementary sex determination (csd) locus in Hymenoptera (ants, bees and wasps), can result in a sharply increased probability of extinction. Their findings illustrate situations in which there is a feedback process between decreased genetic variation at the csd locus owing to genetic drift and decreased population growth, resulting in an extreme type of extinction vortex for these ecologically important organisms.

  17. Lack of renewal effect in extinction of naturally acquired conditioned eyeblink responses, but possible dependency on physical context.

    Science.gov (United States)

    Claassen, J; Mazilescu, L; Thieme, A; Bracha, V; Timmann, D

    2016-01-01

    Context dependency of extinction is well known and has extensively been studied in fear conditioning, but has rarely been assessed in eyeblink conditioning. One way to demonstrate context dependency of extinction is the renewal effect. ABA paradigms are most commonly used to show the renewal effect of extinguished learned fear: if acquisition takes place in context A, and extinction takes place in context B (extinction phase), learned responses will recover in subsequent extinction trials presented in context A (renewal phase). The renewal effect of the visual threat eyeblink response (VTER), a conditioned eyeblink response, which is naturally acquired in early infancy, was examined in a total of 48 young and healthy participants with two experiments using an ABA paradigm. Twenty paired trials were performed in context A (baseline trials), followed by 50 extinction trials in context B (extinction phase) and 50 extinction trials in context A (renewal phase). In 24 participants, contexts A and B were two different rooms, and in the other 24 participants, two different background colors (orange and blue) and noises were used. To rule out spontaneous recovery, an AAA design was used for comparison. There were significant effects of extinction in both experiments. No significant renewal effects were observed. In experiment 2, however, extinction was significantly less using orange background during extinction compared to the blue background. The present findings suggest that extinction of conditioned eyeblinks depends on the physical context. Findings add to the animal literature that context can play a role in the acquisition of classically conditioned eyeblink responses. Future studies, however, need to be performed to confirm the present findings. Lack of renewal effect may be explained by the highly overlearned character of the VTER.

  18. Poverty Alleviation Programmes in Nigeria: Reflections on ...

    African Journals Online (AJOL)

    In it, we have argued that past poverty alleviation policies and programmes have been elitist and non-participatory, especially by the target population. In most cases the designs for poverty alleviations are characterized by improper conceptualization, grandiosity and lack of social justice even in implementation. Based on ...

  19. Harnessing motivation to alleviate neglect

    Directory of Open Access Journals (Sweden)

    Charlotte eRussell

    2013-06-01

    Full Text Available The syndrome of spatial neglect results from the combination of a number of deficits in attention, with patients demonstrating both spatially lateralised and non-lateralised impairments. Previous reports have hinted that there may be a motivational component to neglect and that modulating this might alleviate some of the debilitating symptoms. Additionally, recent work on the effects of reward on attention in healthy participants has revealed improvements across a number of paradigms. As the primary deficit in neglect has been associated with attention, this evidence for reward’s effects is potentially important. However, until very recently there have been few empirical studies addressing this potential therapeutic avenue. Here we review the growing body of evidence that attentional impairments in neglect can be reduced by motivation, for example in the form of preferred music or anticipated monetary reward, and discuss the implications of this for treatments for these patients. Crucially these effects of positive motivation are not observed in all patients with neglect, suggesting that the consequences of motivation may relate to individual lesion anatomy. Given the key role of dopaminergic systems in motivational processes, we suggest that motivational stimulation might act as a surrogate for dopaminergic stimulation. In addition, we consider the relationship between clinical post stroke apathy and lack of response to motivation.

  20. Reconsidering the extinction of ichthyosaurs

    OpenAIRE

    Fischer, Valentin

    2010-01-01

    Despite their extreme adaptation to life in open sea, ichthyosaurs were one of the first major groups of post-Triassic marine reptiles to disappear, at the end of Cenomanian, whereas plesiosaurs, mosasaurs and numerous families of marine crocodiles and sea turtles disappeared during the Cretaceous/Paleocene Extinction Event. It has been proposed that unique biological factors drove ichthyosaurs to extinction, namely a break in the food chain at the level of belemnites or a progressive ecologi...

  1. The Sixth Great Mass Extinction

    Science.gov (United States)

    Wagler, Ron

    2012-01-01

    Five past great mass extinctions have occurred during Earth's history. Humanity is currently in the midst of a sixth, human-induced great mass extinction of plant and animal life (e.g., Alroy 2008; Jackson 2008; Lewis 2006; McDaniel and Borton 2002; Rockstrom et al. 2009; Rohr et al. 2008; Steffen, Crutzen, and McNeill 2007; Thomas et al. 2004;…

  2. Enhancing and impairing extinction of habit memory through modulation of NMDA receptors in the dorsolateral striatum.

    Science.gov (United States)

    Goodman, Jarid; Ressler, Reed L; Packard, Mark G

    2017-06-03

    The present experiments investigated the involvement of N-methyl-d-aspartate (NMDA) receptors of the dorsolateral striatum (DLS) in consolidation of extinction in a habit memory task. Adult male Long-Evans rats were initially trained in a food-reinforced response learning version of a plus-maze task and were subsequently given extinction training in which the food was removed from the maze. In experiment 1, immediately after the first day of extinction training, rats received bilateral intra-DLS injections of the NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid (AP5; 2µg/side) or physiological saline. In experiment 2, immediately following the first day of extinction training, animals were given intra-DLS injections of NMDA receptor partial agonist d-cycloserine (DCS; 10 or 20µg/side) or saline. In both experiments, the number of perseverative trials (a trial in which a rat made the same previously reinforced body-turn response) and latency to reach the previously correct food well were used as measures of extinction behavior. Results indicated that post-training intra-DLS injections of AP5 impaired extinction. In contrast, post-training intra-DLS infusions of DCS (20µg) enhanced extinction. Intra-DLS administration of AP5 or DCS given two hours after extinction training did not influence extinction of response learning, indicating that immediate post-training administration of AP5 and DCS specifically influenced consolidation of the extinction memory. The present results indicate a critical role for DLS NMDA receptors in modulating extinction of habit memory and may be relevant to developing therapeutic approaches to combat the maladaptive habits observed in human psychopathologies in which DLS-dependent memory has been implicated (e.g. drug addiction and relapse and obsessive compulsive disorder). Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  3. Modafinil May Alleviate Poststroke Fatigue

    DEFF Research Database (Denmark)

    Poulsen, Mai Bang; Damgaard, Bodil; Zerahn, Bo

    2015-01-01

    was randomized, double-blinded, and placebo-controlled. Patients were treated with 400-mg modafinil or placebo for 90 days. Assessments were done at inclusion, 30, 90, and 180 days. The primary end point was fatigue at 90 days measured by the Multidimensional Fatigue Inventory-20 general fatigue domain......BACKGROUND AND PURPOSE: Poststroke fatigue is common and reduces quality of life. Current evidence for intervention is limited, and this is the first placebo-controlled trial to investigate treatment of poststroke fatigue with the wakefulness promoting drug modafinil. METHODS: The trial....... Secondary end points included the Fatigue Severity Scale, the Montreal Cognitive Assessment, the modified Rankin Scale and the Stroke-specific quality of Life questionnaire. Adult patients with a recent stroke achieving a score of ≥12 on the Multidimensional Fatigue Inventory-20 general fatigue domain were...

  4. Thermal Transgressions and Phanerozoic Extinctions

    Science.gov (United States)

    Worsley, T. R.; Kidder, D. L.

    2007-12-01

    A number of significant Phanerozoic extinctions are associated with marine transgressions that were probably driven by rapid ocean warming. The conditions associated with what we call thermal transgressions are extremely stressful to life on Earth. The Earth system setting associated with end-Permian extinction exemplifies an end-member case of our model. The conditions favoring extreme warmth and sea-level increases driven by thermal expansion are also conducive to changes in ocean circulation that foster widespread anoxia and sulfidic subsurface ocean waters. Equable climates are characterized by reduced wind shear and weak surface ocean circulation. Late Permian and Early Triassic thermohaline circulation differs considerably from today's world, with minimal polar sinking and intensified mid-latitude sinking that delivers sulfate from shallow evaporative areas to deeper water where it is reduced to sulfide. Reduced nutrient input to oceans from land at many of the extinction intervals results from diminished silicate weathering and weakened delivery of iron via eolian dust. The falloff in iron-bearing dust leads to minimal nitrate production, weakening food webs and rendering faunas and floras more susceptible to extinction when stressed. Factors such as heat, anoxia, ocean acidification, hypercapnia, and hydrogen sulfide poisoning would significantly affect these biotas. Intervals of tectonic quiescence set up preconditions favoring extinctions. Reductions in chemical silicate weathering lead to carbon dioxide buildup, oxygen drawdown, nutrient depletion, wind and ocean current abatement, long-term global warming, and ocean acidification. The effects of extinction triggers such as large igneous provinces, bolide impacts, and episodes of sudden methane release are more potent against the backdrop of our proposed preconditions. Extinctions that have characteristics we call for in the thermal transgressions include the Early Cambrian Sinsk event, as well as

  5. Spatial memory extinction: a c-Fos protein mapping study.

    Science.gov (United States)

    Méndez-Couz, M; Conejo, N M; Vallejo, G; Arias, J L

    2014-03-01

    While the neuronal basis of spatial memory consolidation has been thoroughly studied, the substrates mediating the process of extinction remain largely unknown. This study aimed to evaluate the functional contribution of selected brain regions during the extinction of a previously acquired spatial memory task in the Morris water maze. For that purpose, we used adult male Wistar rats trained in a spatial reference memory task. Learning-related changes in c-Fos inmunoreactive cells after training were evaluated in cortical and subcortical regions. Results show that removal of the hidden platform in the water maze induced extinction of the previously reinforced escape behavior after 16 trials, without spontaneous recovery 24h later. Extinction was related with significantly higher numbers of c-Fos positive nuclei in amygdala nuclei and prefrontal cortex. On the other hand, the lateral mammillary bodies showed higher number of c-Fos positive cells than the control group. Therefore, in contrast with the results obtained in studies of classical conditioning, we show the involvement of diencephalic structures mediating this kind of learning. In summary, our findings suggest that medial prefrontal cortex, the amygdala complex and diencephalic structures like the lateral mammillary nuclei are relevant for the extinction of spatial memory. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Sonic hedgehog signaling regulates amygdalar neurogenesis and extinction of fear memory.

    Science.gov (United States)

    Hung, Hui-Chi; Hsiao, Ya-Hsin; Gean, Po-Wu

    2015-10-01

    It is now recognized that neurogenesis occurs throughout life predominantly in the subgranular zone (SGZ) of the hippocampus and the subventricular zone (SVZ) of the lateral ventricle. In the present study, we investigated the relationship between neurogenesis in the amygdala and extinction of fear memory. Mice received 15 tone-footshock pairings. Twenty-four hours after training, the mice were given 15 tone-alone trials (extinction training) once per day for 7 days. Two hours before extinction training, the mice were injected intraperitoneally with 5-bromo-3-deoxyuridine (BrdU). BrdU-positive and NeuN-positive cells were analyzed 52 days after the training. A group of mice that received tone-footshock pairings but no extinction training served as controls (FC+No-Ext). The number of BrdU(+)/NeuN(+) cells was significantly higher in the extinction (FC+Ext) than in the FC+No-Ext mice. Proliferation inhibitor methylazoxymethanol acetate (MAM) or DNA synthesis inhibitor cytosine arabinoside (Ara-C) reduced neurogenesis and retarded extinction. Silencing Sonic hedgehog (Shh) gene with short hairpin interfering RNA (shRNA) by means of a retrovirus expression system to knockdown Shh specifically in the mitotic neurons reduced neurogenesis and retarded extinction. By contrast, over-expression of Shh increased neurogenesis and facilitated extinction. These results suggest that amygdala neurogenesis and Shh signaling are involved in the extinction of fear memory. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

  7. Poverty Alleviation Programmes and Economic Development in ...

    African Journals Online (AJOL)

    Poverty Alleviation Programmes and Economic Development in Nigeria: A Comparative Assessment of Asa and Ilorin West Local ... Journal Home > Vol 3, No 4 (2009) > ... and worst hit income inequality group with about 84percent of total

  8. Exercise alleviates depression related systemic inflammation in ...

    African Journals Online (AJOL)

    Exercise alleviates depression related systemic inflammation in chronic obstructive pulmonary disease patients. ... African Health Sciences ... Currently, physical activity is an important lifestyle factor that has the potential to modify inflammatory ...

  9. The extinction of the dinosaurs.

    Science.gov (United States)

    Brusatte, Stephen L; Butler, Richard J; Barrett, Paul M; Carrano, Matthew T; Evans, David C; Lloyd, Graeme T; Mannion, Philip D; Norell, Mark A; Peppe, Daniel J; Upchurch, Paul; Williamson, Thomas E

    2015-05-01

    Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past two decades, provide updated and novel analyses of long-term dinosaur diversity trends during the latest Cretaceous, and discuss an emerging consensus on the extinction's tempo and causes. Little support exists for a global, long-term decline across non-avian dinosaur diversity prior to their extinction at the end of the Cretaceous. However, restructuring of latest Cretaceous dinosaur faunas in North America led to reduced diversity of large-bodied herbivores, perhaps making communities more susceptible to cascading extinctions. The abruptness of the dinosaur extinction suggests a key role for the bolide impact, although the coarseness of the fossil record makes testing the effects of Deccan volcanism difficult. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

  10. The promises and pitfalls of retrieval-extinction procedures in preventing relapse to drug seeking

    Directory of Open Access Journals (Sweden)

    Gavan P McNally

    2013-03-01

    Full Text Available Relapse to drug seeking after treatment or a period of abstinence remains a fundamental challenge for drug users. The retrieval – extinction procedure offers promise in augmenting the efficacy of exposure based treatment for drug use and for protecting against relapse to drug seeking. Preceding extinction training with a brief retrieval or reminder trial, retrieval – extinction training, has been shown to reduce reinstatement of extinguished drug seeking in animal models and also to produce profound and long lasting decrements in cue-induced craving in human heroin users. However, the mechanisms that mediate these effects of retrieval - extinction training are unclear. Moreover, under some circumstances, the retrieval – extinction procedure can significantly increase vulnerability to reinstatement in animal models.

  11. The atmospheric extinction of light

    International Nuclear Information System (INIS)

    Hughes, Stephen W; Powell, Sean; Carroll, Joshua; Cowley, Michael

    2016-01-01

    An experiment is described that enables students to understand the properties of atmospheric extinction due to Rayleigh scattering. The experiment requires the use of red, green and blue lasers attached to a travelling microscope or similar device. The laser beams are passed through an artificial atmosphere, made from milky water, at varying depths, before impinging on either a light meter or a photodiode integral to a Picotech Dr. DAQ ADC. A plot of measured spectral intensity verses depth reveals the contribution Rayleigh scattering has to the extinction coefficient. For the experiment with the light meter, the extinction coefficients for red, green and blue light in the milky sample of water were 0.27, 0.36 and 0.47 cm −1 respectively and 0.032, 0.037 and 0.092 cm −1 for the Picotech Dr. DAQ ADC. (paper)

  12. Infectious Disease, Endangerment, and Extinction

    Science.gov (United States)

    MacPhee, Ross D. E.; Greenwood, Alex D.

    2013-01-01

    Infectious disease, especially virulent infectious disease, is commonly regarded as a cause of fluctuation or decline in biological populations. However, it is not generally considered as a primary factor in causing the actual endangerment or extinction of species. We review here the known historical examples in which disease has, or has been assumed to have had, a major deleterious impact on animal species, including extinction, and highlight some recent cases in which disease is the chief suspect in causing the outright endangerment of particular species. We conclude that the role of disease in historical extinctions at the population or species level may have been underestimated. Recent methodological breakthroughs may lead to a better understanding of the past and present roles of infectious disease in influencing population fitness and other parameters. PMID:23401844

  13. Extinction of the weakest

    International Nuclear Information System (INIS)

    Denham, James W.; Kron, Tomas

    2001-01-01

    Purpose: To examine whether changes in the effective doubling time of tumor cells during irradiation of head-and-neck cancer are linked to accumulating dose. Methods and Materials: Optimal fitting of the results of four apparently iso-effective regimens in three recently reported randomized controlled trials (continuous hyperfractionated accelerated radiation therapy [CHART], Radiation Therapy Oncology Group [RTOG] 90-03, and Trans-Tasman Radiation Oncology Group [TROG] 91.01) was attempted using two different types of model of the change in effective doubling time that may occur during treatment. The first involved the traditional approach where doubling time changes at specific times after the start of treatment regardless of fractionation used ('fixed response time' models). The second is where changes in doubling time are linked to accumulating biologic dose ('cellular depletion' models). Results: Changes in effective doubling time occur during radiotherapy for head-and-neck cancer. Data from the three trials can be fitted successfully by functions that imply a continuous reduction in effective doubling time. Models linking the reductions in effective doubling time to the cellular depletion that occurs in the tumor during radiotherapy fit the data satisfactorily. Effective doubling time ultimately reduces to 2 days, or slightly less, during high-dose radiotherapy regimens designed to cure squamous head-and-neck cancer. Conclusions: If the assumption of iso-effectivity is justified then this study indicates that the 'repopulation phenomenon' may be best described by a function that depicts a reduction in effective tumor cell doubling time that decreases continuously during treatment down to a certain minimum value. Furthermore, this reduction may be linked to cellular depletion

  14. Narrowing down the conditions for extinction of Pavlovian feature-positive discriminations in humans

    NARCIS (Netherlands)

    van Vooren, P.R.; Franssen, M.; Beckers, T.; Hermans, D.; Baeyens, F.

    2012-01-01

    The aim of this study was to delineate the minimal conditions for extinction of Pavlovian modulation in humans. Previous experiments at our lab showed that, after X-- A+/A- acquisition training, X- trials did not extinguish differential X-- A+/A- responding, while X-- A- trials did. Additionally,

  15. Block of glucocorticoid synthesis during re-activation inhibits extinction of an established fear memory.

    Science.gov (United States)

    Blundell, Jacqueline; Blaiss, Cory A; Lagace, Diane C; Eisch, Amelia J; Powell, Craig M

    2011-05-01

    The pharmacology of traumatic memory extinction has not been fully characterized despite its potential as a therapeutic target for established, acquired anxiety disorders, including post-traumatic stress disorder (PTSD). Here we examine the role of endogenous glucocorticoids in traumatic memory extinction. Male C57BL/6J mice were injected with corticosterone (10 mg/kg, i.p.) or metyrapone (50 mg/kg, s.c.) during re-activation of a contextual fear memory, and compared to vehicle groups (N=10-12 per group). To ensure that metyrapone was blocking corticosterone synthesis, we measured corticosterone levels following re-activation of a fear memory in metyrapone- and vehicle-treated animals. Corticosterone administration following extinction trials caused a long-lasting inhibition of the original fear memory trace. In contrast, blockade of corticosteroid synthesis with metyrapone prior to extinction trials enhanced retrieval and prevented extinction of context-dependent fear responses in mice. Further behavioral analysis suggested that the metyrapone enhancement of retrieval and prevention of extinction were not due to non-specific alterations in locomotor or anxiety-like behavior. In addition, the inhibition of extinction by metyrapone was rescued by exogenous administration of corticosterone following extinction trials. Finally, we confirmed that the rise in corticosterone during re-activation of a contextual fear memory was blocked by metyrapone. We demonstrate that extinction of a classical contextual fear memory is dependent on endogenous glucocorticoid synthesis during re-activation of a fear memory. Our data suggest that decreased glucocorticoids during fear memory re-activation may contribute to the inability to extinguish a fear memory, thus contributing to one of the core symptoms of PTSD. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Education as a tool for addressing the extinction crisis: Moving students from understanding to action

    Directory of Open Access Journals (Sweden)

    Lucas Moyer-Horner

    2010-12-01

    Full Text Available Human activity is leading to mass species extinctions worldwide. Conservation biology (CB courses, taught worldwide at universities, typically focus on the proximal causes of extinction without teaching students how to respond to this crisis. The Extinction of Species 360 course has been taught yearly each fall semester to several hundred students at the University of Wisconsin-Madison for over two decades. In 2007 the instructor and five teaching assistants combined principles driving extinctions, based on traditional lectures and discussion sections, with action-oriented education targeting individual consumer habits, to a group of 285 students. Students learn the science underpinning conservation efforts, as evidenced by highly significant learning (<.001 gains in a 22 question survey in every measured category, and also make direct and immediate changes in their lifestyle and consumption habits. This course succeeded in each of its three primary goals: a informed students about the value of and threats to biodiversity, similar to traditional CB courses, b emphasized our personal role (as consumers in perpetuating the extinction crisis and c facilitated activities to reduce our impact and help alleviate the crisis. The results suggested students learned CB concepts and understood biodiversity’s value, increased their awareness of the connection between personal consumption and extinction, and reduced their collective ecological footprints. Furthermore, students complemented their learning and multiplied the potential for consumption reduction, by participating in action-based activities. Such academic courses can provide a rigorous treatment of the direct and indirect causes of extinction while developing a student’s sense of personal empowerment to help slow the extinction crisis. Rev. Biol. Trop. 58 (4: 1115-1126. Epub 2010 December 01.

  17. Temporal properties of fear extinction--does time matter?

    Science.gov (United States)

    Golkar, Armita; Bellander, Martin; Öhman, Arne

    2013-02-01

    Fear extinction can be defined as the weakening of the expression of a conditioned response (CR) by extended experience of nonreinforcement. Conceptually, two distinct models have been invoked to account for extinction. R. A. Rescorla and A. R. Wagner (1972, A theory of Pavlovian conditioning: Variations in the effectiveness of reinforcement and nonreinforcement, in A. H. B. W. F. Prokasy (Ed.), Classical conditioning: II. Current research and theory, pp. 64-99, New York, NY, Appleton-Century-Crofts) postulated that the number of exposure trials is the primary determinant of CR decrement, whereas C. R. Gallistel and J. Gibbon (2000, Time, rate, and conditioning, Psychological Review, Vol. 107, pp. 289-344) proposed that the decisive event is the cumulated exposure time to the nonreinforced conditioned stimulus (CS) elapsed after the last CS reinforcement. We evaluated these two accounts in a human differential fear conditioning study in which CR was measured with the fear-potentiated startle response. Cumulated duration of nonreinforcement fails to explain our findings, whereas the number of trials appeared critical. In fact, many CS trials with a duration shorter than the acquisition CS duration facilitated within-session extinction, but this effect did not predict the recovery of fear. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

  18. Effects of a Context Shift and Multiple Context Extinction on Reactivity to Alcohol Cues

    Science.gov (United States)

    MacKillop, James; Lisman, Stephen A.

    2008-01-01

    Cue exposure treatment (CET) attempts to reduce the influence of conditioned substance cues on addictive behavior via prolonged cue exposure with response prevention (i.e., extinction), but has received only modest empirical support in clinical trials. This may be because extinction learning appears to be context dependent and a change in context may result in a return of conditioned responding (i.e., renewal), although this has received only limited empirical examination. The current study used a four-session laboratory analogue of CET to examine whether a change in context following three sessions of alcohol cue exposure with response prevention would result in renewal of conditioned responding. In addition, this study examined whether conducting extinction in multiple contexts would attenuate renewal of conditioned responding. In a one-way between-subjects design, 73 heavy drinkers (71% male) were randomized to three conditions: 1) single context extinction (extinction to alcohol cues in the same context for three sessions followed by a context shift at the fourth session); 2) multiple context extinction (extinction to alcohol cues in different contexts each day for all four sessions); and 3) pseudo-extinction control condition (exposure to neutral cues in the same context for three sessions followed by exposure to alcohol cues at the fourth session). The results revealed the predicted cue reactivity and extinction effects, but the hypotheses that a context shift would generate renewed cue reactivity and that multiple contexts would enhance extinction were not supported. Methodological aspects of the study and the need for parametric data on the context dependency of extinction to alcohol cues are discussed. PMID:18729687

  19. Extinction phenomena: A biologic perspective on how and why psychoanalysis works

    Directory of Open Access Journals (Sweden)

    Linda A.W. Brakel

    2011-09-01

    Full Text Available This article presents the view that much of the success of classical psychoanalysis is centrally predicated on its biological potency; focusing not on neuropsychology, but on the biology of conditioning. The argument suggests that features of classic psychoanalytic technique--the couch, meetings several times per week with both parties present, and free association--uniquely facilitate intense transferences of various sorts, and that these in turn constitute the multiple and diverse extinction trials necessary to best approximate extinction.

  20. Involvement of Dopamine D1/D5 and D2 Receptors in Context-Dependent Extinction Learning and Memory Reinstatement.

    Science.gov (United States)

    André, Marion Agnès Emma; Manahan-Vaughan, Denise

    2015-01-01

    Dopamine contributes to the regulation of higher order information processing and executive control. It is important for memory consolidation processes, and for the adaptation of learned responses based on experience. In line with this, under aversive learning conditions, application of dopamine receptor antagonists prior to extinction result in enhanced memory reinstatement. Here, we investigated the contribution of the dopaminergic system to extinction and memory reinstatement (renewal) of an appetitive spatial learning task in rodents. Rats were trained for 3 days in a T-maze (context "A") to associate a goal arm with a food reward, despite low reward probability (acquisition phase). On day 4, extinction learning (unrewarded) occurred, that was reinforced by a context change ("B"). On day 5, re-exposure to the (unrewarded) "A" context took place (renewal of context "A", followed by extinction of context "A"). In control animals, significant extinction occurred on day 4, that was followed by an initial memory reinstatement (renewal) on day 5, that was, in turn, succeeded by extinction of renewal. Intracerebral treatment with a D1/D5-receptor antagonist prior to the extinction trials, elicited a potent enhancement of extinction in context "B". By contrast, a D1/D5-agonist impaired renewal in context "A". Extinction in the "A" context on day 5 was unaffected by the D1/D5-ligands. Treatment with a D2-receptor antagonist prior to extinction had no overall effect on extinction in context "B" or renewal in context "A", although extinction of the renewal effect was impaired on day 5, compared to controls. Taken together, these data suggest that dopamine acting on the D1/D5-receptor modulates both acquisition and consolidation of context-dependent extinction. By contrast, the D2-receptor may contribute to context-independent aspects of this kind of extinction learning.

  1. Involvement of dopamine D1/D5 and D2 receptors in context-dependent extinction learning and memory reinstatement

    Directory of Open Access Journals (Sweden)

    Marion Agnes Emma Andre

    2016-01-01

    Full Text Available Dopamine contributes to the regulation of higher order information processing and executive control. It is important for memory consolidation processes, and for the adaptation of learned responses based on experience. In line with this, under aversive learning conditions, application of dopamine receptor antagonists prior to extinction result in enhanced memory reinstatement. Here, we investigated the contribution of the dopaminergic system to extinction and memory reinstatement (renewal of an appetitive spatial learning task in rodents. Rats were trained for 3 days in a T-maze (context ‘A’ to associate a goal arm with a food reward, despite low reward probability (acquisition phase. On day 4, extinction learning (unrewarded occurred, that was reinforced by a context change (‘B’. On day 5, re-exposure to the (unrewarded ‘A’-context took place (renewal of context ‘A’, followed by extinction of context ‘A’. In control animals, significant extinction occurred on day 4, that was followed by an initial memory reinstatement (renewal on day 5, that was, in turn, succeeded by extinction of renewal. Intracerebral treatment with a D1/D5-receptor antagonist prior to the extinction trials, elicited a potent enhancement of extinction in context ‘B’. By contrast, a D1/D5-agonist impaired renewal in context ’A’. Extinction in the ‘A’ context on day 5 was unaffected by the D1/D5-ligands. Treatment with a D2-receptor antagonist prior to extinction had no overall effect on extinction in context ‘B or renewal in context ‘A’, although extinction of the renewal effect was impaired on day 5, compared to controls.Taken together, these data suggest that dopamine acting on the D1/D5-receptor modulates both acquisition and consolidation of context-dependent extinction. By contrast, the D2-receptor may contribute to context-independent aspects of this kind of extinction learning.

  2. Animal models of extinction-induced depression: loss of reward and its consequences.

    Science.gov (United States)

    Huston, Joseph P; Silva, Maria A de Souza; Komorowski, Mara; Schulz, Daniela; Topic, Bianca

    2013-11-01

    The absence or loss of rewards or reinforcers holds a major role in the development of depression in humans. In spite of the prevalence of extinction-induced depression (EID) in humans, few attempts have been made to establish animal models thereof. Here we present the concept of extinction-related depression and summarize the results of two sets of studies in our attempt to create animal models of EID, one set based on extinction after positive reinforcement in the Skinner-box, the other on extinction after negative reinforcement - escape from water. We found various behaviors emitted during the extinction trials that responded to treatment with antidepressant drugs: Accordingly, the important behavioral marker for EID during extinction of escape from the water was immobility. During extinction after positive reinforcement the important indices for extinction-induced depression are the withdrawal from the former site of reward, biting behavior and rearing up on the hind legs. Avoidance behavior and biting may model aspects of human depressive behavior, which may include withdrawal or avoidance as well as aggressive-like behaviors. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Mass Extinctions and Supernova Explosions

    Science.gov (United States)

    Korschinek, Gunther

    A nearby supernova (SN) explosion could have negatively influenced life on Earth, maybe even been responsible for mass extinctions. Mass extinction poses a significant extinction of numerous species on Earth, as recorded in the paleontologic, paleoclimatic, and geological record of our planet. Depending on the distance between the Sun and the SN, different types of threats have to be considered, such as ozone depletion on Earth, causing increased exposure to the Sun's ultraviolet radiation or the direct exposure of lethal X-rays. Another indirect effect is cloud formation, induced by cosmic rays in the atmosphere which result in a drop in the Earth's temperature, causing major glaciations of the Earth. The discovery of highly intensive gamma-ray bursts (GRBs), which could be connected to SNe, initiated further discussions on possible life-threatening events in the Earth's history. The probability that GRBs hit the Earth is very low. Nevertheless, a past interaction of Earth with GRBs and/or SNe cannot be excluded and might even have been responsible for past extinction events.

  4. Modeling Population Growth and Extinction

    Science.gov (United States)

    Gordon, Sheldon P.

    2009-01-01

    The exponential growth model and the logistic model typically introduced in the mathematics curriculum presume that a population grows exclusively. In reality, species can also die out and more sophisticated models that take the possibility of extinction into account are needed. In this article, two extensions of the logistic model are considered,…

  5. New theories about ancient extinctions

    Science.gov (United States)

    Spall, H.

    1986-01-01

    The abrupt disappearance of all the dinosaurs about 65 million years ago, along with perhaps half the plant species and other animals, has been one of the great geological mysteries. Clues to the cause of these extinctions have been scarce and open to many interpretations.

  6. Extinction debt on oceanic islands

    DEFF Research Database (Denmark)

    Triantis, Kostas A.; Borges, Paulo A. V.; Ladle, Richard J.

    2010-01-01

    the magnitude of such future extinction events has been hampered by potentially inaccurate assumptions about the slope of species-area relationships, which are habitat- and taxon-specific. We overcome this challenge by applying a method that uses the historical sequence of deforestation in the Azorean Islands...

  7. The currency and tempo of extinction.

    Science.gov (United States)

    Regan, H M; Lupia, R; Drinnan, A N; Burgman, M A

    2001-01-01

    This study examines estimates of extinction rates for the current purported biotic crisis and from the fossil record. Studies that compare current and geological extinctions sometimes use metrics that confound different sources of error and reflect different features of extinction processes. The per taxon extinction rate is a standard measure in paleontology that avoids some of the pitfalls of alternative approaches. Extinction rates reported in the conservation literature are rarely accompanied by measures of uncertainty, despite many elements of the calculations being subject to considerable error. We quantify some of the most important sources of uncertainty and carry them through the arithmetic of extinction rate calculations using fuzzy numbers. The results emphasize that estimates of current and future rates rely heavily on assumptions about the tempo of extinction and on extrapolations among taxa. Available data are unlikely to be useful in measuring magnitudes or trends in current extinction rates.

  8. Evaluating differences in Pavlovian fear acquisition and extinction as predictors of outcome from cognitive behavioural therapy for anxious children.

    Science.gov (United States)

    Waters, Allison M; Pine, Daniel S

    2016-07-01

    Extinction is a key theoretical model of exposure-based treatments, such as cognitive behavioural therapy (CBT). This study examined whether individual differences in physiological responses and subjective stimulus evaluations as indices of fear extinction predicted response to CBT. Thirty-two nonanxious comparisons and 44 anxious, 7-to-13-year-old children completed a Pavlovian conditioning and extinction task. Anxious children then completed group-based CBT. Skin conductance responses (SCRs) as well as subjective arousal and valence evaluations were measured in response to a conditioned stimulus paired with an aversive tone (CS+) and another conditioned stimulus presented alone (CS-). Both stimuli were presented alone during extinction. Diagnostic and symptom measures were completed before and after treatment. Like nonanxious comparisons, treatment responders did not acquire conditioned negative stimulus evaluations and displayed elevated SCRs that declined significantly across extinction trials. Nonresponders, by contrast, showed elevated negative stimulus evaluations of both CSs that were sensitive to extinction trials but showed no change in SCRs during extinction. Change in physiological but not evaluative indices of fear extinction predicted better treatment outcomes. Individual differences in evaluative and physiological indices of fear extinction might moderate response to CBT. © 2016 Association for Child and Adolescent Mental Health.

  9. EARTH SCIENCE: Did Volcanoes Drive Ancient Extinctions?

    Science.gov (United States)

    Kerr, R A

    2000-08-18

    With the publication in recent weeks of two papers on a mass extinction 183 million years ago, researchers can add five suggestive cases to the list of extinctions with known causes. These extinctions coincide with massive outpourings of lava, accompanied by signs that global warming threw the ocean-atmosphere system out of whack. Although no one can yet pin any of these mass extinctions with certainty on the volcanic eruptions, scientists say it's unlikely that they're all coincidences.

  10. An investigation of the interstellar extinction

    International Nuclear Information System (INIS)

    Roche, P.F.; Aitken, D.K.; Melbourne Univ., Point Cook

    1984-01-01

    The 10 μm extinction towards six WC8 or WC9 Wolf-Rayet stars is investigated. All objects show smooth dust emission suffering silicate absorption with depths well correlated with the extinction in the visible. The de-reddened spectra are well represented by emission from featureless grain components, possibly from iron or carbon grains. The extinction to the stars is found to be dominantly interstellar in origin with little extinction from the circumstellar shell. (author)

  11. Further Evidence of Auditory Extinction in Aphasia

    Science.gov (United States)

    Marshall, Rebecca Shisler; Basilakos, Alexandra; Love-Myers, Kim

    2013-01-01

    Purpose: Preliminary research ( Shisler, 2005) suggests that auditory extinction in individuals with aphasia (IWA) may be connected to binding and attention. In this study, the authors expanded on previous findings on auditory extinction to determine the source of extinction deficits in IWA. Method: Seventeen IWA (M[subscript age] = 53.19 years)…

  12. D-cycloserine enhances generalization of fear extinction in children.

    Science.gov (United States)

    Byrne, Simon P; Rapee, Ronald M; Richardson, Rick; Malhi, Gin S; Jones, Michael; Hudson, Jennifer L

    2015-06-01

    For exposure therapy to be successful, it is essential that fear extinction learning extends beyond the treatment setting. D-cycloserine (DCS) may facilitate treatment gains by increasing generalization of extinction learning, however, its effects have not been tested in children. We examined whether DCS enhanced generalization of fear extinction learning across different stimuli and contexts among children with specific phobias. The study was a double-blind placebo-controlled randomized controlled trial among dog or spider phobic children aged 6-14. Participants ingested either 50 mg of DCS (n = 18) or placebo (n = 17) before receiving a single prolonged exposure session to their feared stimulus. Return of fear was examined 1 week later to a different stimulus (a different dog or spider), presented in both the original treatment context and an alternate context. Avoidance and fear were measured with Behavior Approach Tests (BATs), where the child was asked to increase proximity to the stimulus while reporting their fear level. There were no differences in BAT performance between groups during the exposure session or when a new stimulus was later presented in the treatment context. However, when the new stimulus was presented in a different context, relative to placebo, the DCS group showed less avoidance (P = .03) and less increase in fear (P = .04) with moderate effect sizes. DCS enabled children to better retain their fear extinction learning. This new learning generalized to different stimuli and contexts. © 2015 Wiley Periodicals, Inc.

  13. Facilitation of extinction of operant behaviour in C57Bl/6 mice by chlordiazepoxide and D-cycloserine.

    Science.gov (United States)

    Leslie, Julian C; Norwood, Kelly; Kennedy, Paul J; Begley, Michael; Shaw, David

    2012-09-01

    Effects on the extinction of GABAergic drug, chlordiazepoxide (CDP), and glutamatergic drug, D: -cycloserine (DCS), in C57BL/6 mice were compared. Following a palatability test (Experiment 1), Experiments 2-6 involved food-reinforced lever press training followed by extinction sessions at 1- or 4-day intervals. The effects of drugs were examined. Experiment 7 involved a two-lever task. CDP did not affect food palatability (Experiment 1), but facilitated extinction when administered prior to extinction sessions via intracerebral (Experiment 2) or peripheral administration at 1-day (Experiments 3-7) or 4-day intervals (Experiment 6). Reducing the amount of training prior to extinction reduced the delay in the effect of CDP typically seen, and CDP had a larger effect in early sessions on mice that had received less training (Experiment 3). There was some evidence that CDP could be blocked by flumazenil (Experiment 4), and CDP withdrawal reversed extinction facilitation (Experiments 5 and 7). With 4-day intervals, DCS administered immediately following extinction sessions, or pre-session CDP, facilitated extinction with 48-trial sessions (experiment 6B). With six-trial sessions, the co-administration of post-session DCS enhanced facilitation produced by pre-session CDP (experiment 6A). Finally, CDP facilitated extinction in a dose-related fashion following training on a two-lever food-reinforced task (Experiment 7). The findings are consistent with the hypotheses that two neurotransmitter systems have different roles in operant extinction and that glutamatergic systems are involved in extinction learning and GABAergic systems involved in the expression of that learning. This parallels findings with extinction following Pavlovian conditioning, which has been more extensively investigated.

  14. Predicting extinction rates in stochastic epidemic models

    International Nuclear Information System (INIS)

    Schwartz, Ira B; Billings, Lora; Dykman, Mark; Landsman, Alexandra

    2009-01-01

    We investigate the stochastic extinction processes in a class of epidemic models. Motivated by the process of natural disease extinction in epidemics, we examine the rate of extinction as a function of disease spread. We show that the effective entropic barrier for extinction in a susceptible–infected–susceptible epidemic model displays scaling with the distance to the bifurcation point, with an unusual critical exponent. We make a direct comparison between predictions and numerical simulations. We also consider the effect of non-Gaussian vaccine schedules, and show numerically how the extinction process may be enhanced when the vaccine schedules are Poisson distributed

  15. Trials

    Directory of Open Access Journals (Sweden)

    Michele Fornaro

    2010-01-01

    Full Text Available Mental Retardation (MR is a developmental disability characterized by impairments in adaptive daily life skills and difficulties in social and interpersonal functioning. Since multiple causes may contribute to MR, associated clinical pictures may vary accordingly. Nevertheless, when psychiatric disorders as Treatment Resistant Depression (TRD and/or alcohol abuse co-exist, their proper detection and management is often troublesome, essentially due to a limited vocabulary MR people could use to describe their symptoms, feelings and concerns, and the lack of reliable screening tools. Furthermore, MR people are among the most medicated subjects, with (over prescription of antidepressants and/or typical antipsychotics being the rule rather than exception. Thus, treatment resistance or even worsening of depression, constitute frequent occurrences. This report describes the case of a person with MR who failed to respond to repetitive trials of antidepressant monotherapies, finally recovering using aripiprazole to fluvoxamine augmentation upon consideration of a putative bipolar diathesis for “agitated” TRD. Although further controlled investigations are needed to assess a putative bipolar diathesis in some cases of MR associated to TRD, prudence is advised in the long-term prescription of antidepressant monotherapies in such conditions.

  16. Extinction risk escalates in the tropics.

    Directory of Open Access Journals (Sweden)

    Jana C Vamosi

    Full Text Available The latitudinal biodiversity gradient remains one of the most widely recognized yet puzzling patterns in nature. Presently, the high level of extinction of tropical species, referred to as the "tropical biodiversity crisis", has the potential to erode this pattern. While the connection between species richness, extinction, and speciation has long intrigued biologists, these interactions have experienced increased poignancy due to their relevancy to where we should concentrate our conservation efforts. Natural extinction is a phenomenon thought to have its own latitudinal gradient, with lower extinction rates in the tropics being reported in beetles, birds, mammals, and bivalves. Processes that have buffered ecosystems from high extinction rates in the past may also buffer ecosystems against disturbance of anthropogenic origin. While potential parallels between historical and present-day extinction patterns have been acknowledged, they remain only superficially explored and plant extinction patterns have been particularly neglected. Studies on the disappearances of animal species have reached conflicting conclusions, with the rate of extinction appearing either higher or lower in species richness hotspots. Our global study of extinction risk in vascular plants finds disproportionately higher extinction risk in tropical countries, even when indicators of human pressure (GDP, population density, forest cover change are taken into account. Our results are at odds with the notion that the tropics represent a museum of plant biodiversity (places of historically lowered extinction and we discuss mechanisms that may reconcile this apparent contradiction.

  17. Extinction risk escalates in the tropics.

    Science.gov (United States)

    Vamosi, Jana C; Vamosi, Steven M

    2008-01-01

    The latitudinal biodiversity gradient remains one of the most widely recognized yet puzzling patterns in nature. Presently, the high level of extinction of tropical species, referred to as the "tropical biodiversity crisis", has the potential to erode this pattern. While the connection between species richness, extinction, and speciation has long intrigued biologists, these interactions have experienced increased poignancy due to their relevancy to where we should concentrate our conservation efforts. Natural extinction is a phenomenon thought to have its own latitudinal gradient, with lower extinction rates in the tropics being reported in beetles, birds, mammals, and bivalves. Processes that have buffered ecosystems from high extinction rates in the past may also buffer ecosystems against disturbance of anthropogenic origin. While potential parallels between historical and present-day extinction patterns have been acknowledged, they remain only superficially explored and plant extinction patterns have been particularly neglected. Studies on the disappearances of animal species have reached conflicting conclusions, with the rate of extinction appearing either higher or lower in species richness hotspots. Our global study of extinction risk in vascular plants finds disproportionately higher extinction risk in tropical countries, even when indicators of human pressure (GDP, population density, forest cover change) are taken into account. Our results are at odds with the notion that the tropics represent a museum of plant biodiversity (places of historically lowered extinction) and we discuss mechanisms that may reconcile this apparent contradiction.

  18. Extinction Coefficient of Gold Nanostars.

    Science.gov (United States)

    de Puig, Helena; Tam, Justina O; Yen, Chun-Wan; Gehrke, Lee; Hamad-Schifferli, Kimberly

    2015-07-30

    Gold nanostars (NStars) are highly attractive for biological applications due to their surface chemistry, facile synthesis and optical properties. Here, we synthesize NStars in HEPES buffer at different HEPES/Au ratios, producing NStars of different sizes and shapes, and therefore varying optical properties. We measure the extinction coefficient of the synthesized NStars at their maximum surface plasmon resonances (SPR), which range from 5.7 × 10 8 to 26.8 × 10 8 M -1 cm -1 . Measured values correlate with those obtained from theoretical models of the NStars using the discrete dipole approximation (DDA), which we use to simulate the extinction spectra of the nanostars. Finally, because NStars are typically used in biological applications, we conjugate DNA and antibodies to the NStars and calculate the footprint of the bound biomolecules.

  19. Dinasour extinction and volcanic activity

    Science.gov (United States)

    Gledhill, J. A.

    There is at present some controversy about the reason for the mass extinction of dinosaurs and other forms of life at the end of the Cretaceous. A suggestion by Alvarez et al. [1980] that this was due to the collision of the earth with a meteorite 10 km or so in diameter has excited considerable interest [Silver and Schultz, 1982] and also some criticism [Stanley, 1984]. A recent publication [Wood, 1984] describing the catastrophic effects of a relatively minor lava flow in Iceland suggests that intense volcanic activity could have played a large part in the extinctions. In this letter it is pointed out that the Deccan lava flows in India took place in the appropriate time and may well have been of sufficient magnitude to be a major factor in the Cretaceous-Tertiary (C-T) boundary catastrophe.

  20. [Extinction and Reconsolidation of Memory].

    Science.gov (United States)

    Zuzina, A B; Balaban, P M

    2015-01-01

    Retrieval of memory followed by reconsolidation can strengthen a memory, while retrieval followed by extinction results in a decrease of memory performance due to weakening of existing memory or formation of a competing memory. In our study we analyzed the behavior and responses of identified neurons involved in the network underlying aversive learning in terrestrial snail Helix, and made an attempt to describe the conditions in which the retrieval of memory leads either to extinction or reconsolidation. In the network underlying the withdrawal behavior, sensory neurons, premotor interneurons, motor neurons, and modulatory for this network serotonergic neurons are identified and recordings from representatives of these groups were made before and after aversive learning. In the network underlying feeding behavior, the premotor modulatory serotonergic interneurons and motor neurons involved in motor program of feeding are identified. Analysis of changes in neural activity after aversive learning showed that modulatory neurons of feeding behavior do not demonstrate any changes (sometimes a decrease of responses to food was observed), while responses to food in withdrawal behavior premotor interneurons changed qualitatively, from under threshold EPSPs to spike discharges. Using a specific for serotonergic neurons neurotoxin 5,7-DiHT it was shown previously that the serotonergic system is necessary for the aversive learning, but is not necessary for maintenance and retrieval of this memory. These results suggest that the serotonergic neurons that are necessary as part of a reinforcement for developing the associative changes in the network may be not necessary for the retrieval of memory. The hypothesis presented in this review concerns the activity of the "reinforcement" serotonergic neurons that is suggested to be the gate condition for the choice between extinction/reconsolidation triggered by memory retrieval: if these serotonergic neurons do not respond during the

  1. Optimising Extinction of Conditioned Disgust.

    Science.gov (United States)

    Bosman, Renske C; Borg, Charmaine; de Jong, Peter J

    2016-01-01

    Maladaptive disgust responses are tenacious and resistant to exposure-based interventions. In a similar vein, laboratory studies have shown that conditioned disgust is relatively insensitive to Conditioned Stimulus (CS)-only extinction procedures. The relatively strong resistance to extinction might be explained by disgust's adaptive function to motivate avoidance from contamination threats (pathogens) that cannot be readily detected and are invisible to the naked eye. Therefore, the mere visual presentation of unreinforced disgust eliciting stimuli might not be sufficient to correct a previously acquired threat value of the CS+. Following this, the current study tested whether the efficacy of CS-only exposure can be improved by providing additional safety information about the CS+. For the CSs we included two neutral items a pea soup and a sausage roll, whereas for the Unconditioned Stimulus (US) we used one video clip of a woman vomiting and a neutral one about glass blowing. The additional safety information was conveyed by allowing actual contact with the CS+ or by observing an actress eating the food items representing the CS+. When additional safety information was provided via allowing direct contact with the CS+, there was a relatively strong post-extinction increase in participants' willingness-to-eat the CS+. This beneficial effect was still evident at one-week follow up. Also self-reported disgust was lower at one-week follow up when additional safety information was provided. The current findings help explain why disgust is relatively insensitive to CS-only extinction procedures, and provide helpful starting points to improve interventions that are aimed to reduce distress in disgust-related psychopathology.

  2. Optimising Extinction of Conditioned Disgust.

    Directory of Open Access Journals (Sweden)

    Renske C Bosman

    Full Text Available Maladaptive disgust responses are tenacious and resistant to exposure-based interventions. In a similar vein, laboratory studies have shown that conditioned disgust is relatively insensitive to Conditioned Stimulus (CS-only extinction procedures. The relatively strong resistance to extinction might be explained by disgust's adaptive function to motivate avoidance from contamination threats (pathogens that cannot be readily detected and are invisible to the naked eye. Therefore, the mere visual presentation of unreinforced disgust eliciting stimuli might not be sufficient to correct a previously acquired threat value of the CS+. Following this, the current study tested whether the efficacy of CS-only exposure can be improved by providing additional safety information about the CS+. For the CSs we included two neutral items a pea soup and a sausage roll, whereas for the Unconditioned Stimulus (US we used one video clip of a woman vomiting and a neutral one about glass blowing. The additional safety information was conveyed by allowing actual contact with the CS+ or by observing an actress eating the food items representing the CS+. When additional safety information was provided via allowing direct contact with the CS+, there was a relatively strong post-extinction increase in participants' willingness-to-eat the CS+. This beneficial effect was still evident at one-week follow up. Also self-reported disgust was lower at one-week follow up when additional safety information was provided. The current findings help explain why disgust is relatively insensitive to CS-only extinction procedures, and provide helpful starting points to improve interventions that are aimed to reduce distress in disgust-related psychopathology.

  3. Extinction Coefficient of Gold Nanostars

    OpenAIRE

    de Puig, Helena; Tam, Justina O.; Yen, Chun-Wan; Gehrke, Lee; Hamad-Schifferli, Kimberly

    2015-01-01

    Gold nanostars (NStars) are highly attractive for biological applications due to their surface chemistry, facile synthesis and optical properties. Here, we synthesize NStars in HEPES buffer at different HEPES/Au ratios, producing NStars of different sizes and shapes, and therefore varying optical properties. We measure the extinction coefficient of the synthesized NStars at their maximum surface plasmon resonances (SPR), which range from 5.7 × 108 to 26.8 × 108 M−1cm−1. Measured values correl...

  4. Alleviating gizzard erosion with Hepasan ® - Provisional ...

    African Journals Online (AJOL)

    Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. DOWNLOAD FULL TEXT Open Access DOWNLOAD FULL TEXT Subscription or Fee Access. Alleviating gizzard erosion with Hepasan® - Provisional Communication. K Boa-Amponsem, A Osei-Somuah. Full Text:.

  5. Alleviating Poverty Through Vocational Education: The Nigerian ...

    African Journals Online (AJOL)

    The paper concludes that well-articulated vocational education policy and programmes will assist in employment generations and poverty reduction in Nigeria. Keywords: Alleviating Poverty, Vocational Education, Nigerian Experience Journal of Technology and Education in Nigeria Vol. 10 (2) 2005: pp. 10-14 ...

  6. Chinese herbal medicine alleviating hyperandrogenism of PCOS ...

    African Journals Online (AJOL)

    Background: Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder in women hence Chinese herbal medicine (CHM) has been chosen by many clinicians and patients as alternative treatment for PCOS. The present study was to explore the effects of CHM in alleviating hyperandrogenism of PCOS ...

  7. GLP-1 nanomedicine alleviates gut inflammation.

    Science.gov (United States)

    Anbazhagan, Arivarasu N; Thaqi, Mentor; Priyamvada, Shubha; Jayawardena, Dulari; Kumar, Anoop; Gujral, Tarunmeet; Chatterjee, Ishita; Mugarza, Edurne; Saksena, Seema; Onyuksel, Hayat; Dudeja, Pradeep K

    2017-02-01

    The gut hormone, glucagon like peptide-1 (GLP-1) exerts anti-inflammatory effects. However, its clinical use is limited by its short half-life. Previously, we have shown that GLP-1 as a nanomedicine (GLP-1 in sterically stabilized phospholipid micelles, GLP-1-SSM) has increased in vivo stability. The current study was aimed at testing the efficacy of this GLP-1 nanomedicine in alleviating colonic inflammation and associated diarrhea in dextran sodium sulfate (DSS) induced mouse colitis model. Our results show that GLP-1-SSM treatment markedly alleviated the colitis phenotype by reducing the expression of pro-inflammatory cytokine IL-1β, increasing goblet cells and preserving intestinal epithelial architecture in colitis model. Further, GLP-1-SSM alleviated diarrhea (as assessed by luminal fluid) by increasing protein expression of intestinal chloride transporter DRA (down regulated in adenoma). Our results indicate that GLP-1 nanomedicine may act as a novel therapeutic tool in alleviating gut inflammation and associated diarrhea in inflammatory bowel disease (IBD). Published by Elsevier Inc.

  8. Extinction correction and synchrotron radiation

    International Nuclear Information System (INIS)

    Suortti, P.

    1983-01-01

    The primary extinction factor ysub(p) is defined as the ratio of the integrated reflection from a coherently diffracting domain to the integrated kinematical reflection from the same domain. When ysub(p) is larger than 0.5 it may be approximated by ysub(p)= exp[-(αdelta) 2 ], where α is about 0.5 and delta the average size of the coherent domain when measured in units of the extinction length Λ, delta = D/Λ. Transfer equations are applied to symmetrical Laue diffraction, and the reflectivity per unit length, sigma(epsilon) is solved from the measured reflecting ratio as a function of the rocking angle epsilon = theta -thetasub(B). Measurements with conventional x-ray sources are made on single crystal slabs of Be and Si using AgKβ, MoKα 1 and CuKα radiation. The primary extinction factor ysub(p)(epsilon) is solved from a point-by-point comparison of two measurements where the extinction length Λ is changed by varying the polarization and/or wavelength of the x-ray beam. The results show that primary and secondary extinction are strongly correlated, and that the customary assumption of independent size and orientation distributions of crystal mosaics is unjustified. The structure factors for Be and Si show close agreement with other recent measurements and calculations. The limitations of the method are discussed in length, particularly the effects of beam divergences and incoherence of the rays in the crystal. It is concluded that under typical experimental conditions the requirements of the theory are met. Practical limitations arising from the use of characteristic wavelengths and unpolarized radiation prohibit the use of the full potential of the method. The properties of a synchrotron radiation source are compared with a conventional x-ray source, and it is demonstrated that the experimental limitations can be removed by the use of synchrotron radiation. A diffraction experiment with synchrotron radiation is outlined, as well as generalization of the

  9. Biological correlates of extinction risk in bats.

    Science.gov (United States)

    Jones, Kate E; Purvis, Andy; Gittleman, John L

    2003-04-01

    We investigated patterns and processes of extinction and threat in bats using a multivariate phylogenetic comparative approach. Of nearly 1,000 species worldwide, 239 are considered threatened by the International Union for Conservation of Nature and Natural Resources (IUCN) and 12 are extinct. Small geographic ranges and low wing aspect ratios are independently found to predict extinction risk in bats, which explains 48% of the total variance in IUCN assessments of threat. The pattern and correlates of extinction risk in the two bat suborders are significantly different. A higher proportion (4%) of megachiropteran species have gone extinct in the last 500 years than microchiropteran bats (0.3%), and a higher proportion is currently at risk of extinction (Megachiroptera: 34%; Microchiroptera: 22%). While correlates of microchiropteran extinction risk are the same as in the order as a whole, megachiropteran extinction is correlated more with reproductive rate and less with wing morphology. Bat extinction risk is not randomly distributed phylogenetically: closely related species have more similar levels of threat than would be expected if extinction risk were random. Given the unbalanced nature of the evolutionary diversification of bats, it is probable that the amount of phylogenetic diversity lost if currently threatened taxa disappear may be greater than in other clades with numerically more threatened species.

  10. The ethics of reviving long extinct species.

    Science.gov (United States)

    Sandler, Ronald

    2014-04-01

    There now appears to be a plausible pathway for reviving species that have been extinct for several decades, centuries, or even millennia. I conducted an ethical analysis of de-extinction of long extinct species. I assessed several possible ethical considerations in favor of pursuing de-extinction: that it is a matter of justice; that it would reestablish lost value; that it would create new value; and that society needs it as a conservation last resort. I also assessed several possible ethical arguments against pursuing de-extinction: that it is unnatural; that it could cause animal suffering; that it could be ecologically problematic or detrimental to human health; and that it is hubristic. There are reasons in favor of reviving long extinct species, and it can be ethically acceptable to do so. However, the reasons in favor of pursuing de-extinction do not have to do with its usefulness in species conservation; rather, they concern the status of revived species as scientific and technological achievements, and it would be ethically problematic to promote de-extinction as a significant conservation strategy, because it does not prevent species extinctions, does not address the causes of extinction, and could be detrimental to some species conservation efforts. Moreover, humanity does not have a responsibility or obligation to pursue de-extinction of long extinct species, and reviving them does not address any urgent problem. Therefore, legitimate ecological, political, animal welfare, legal, or human health concerns associated with a de-extinction (and reintroduction) must be thoroughly addressed for it to be ethically acceptable. © 2013 Society for Conservation Biology.

  11. Extinction debt: a challenge for biodiversity conservation.

    Science.gov (United States)

    Kuussaari, Mikko; Bommarco, Riccardo; Heikkinen, Risto K; Helm, Aveliina; Krauss, Jochen; Lindborg, Regina; Ockinger, Erik; Pärtel, Meelis; Pino, Joan; Rodà, Ferran; Stefanescu, Constantí; Teder, Tiit; Zobel, Martin; Steffan-Dewenter, Ingolf

    2009-10-01

    Local extinction of species can occur with a substantial delay following habitat loss or degradation. Accumulating evidence suggests that such extinction debts pose a significant but often unrecognized challenge for biodiversity conservation across a wide range of taxa and ecosystems. Species with long generation times and populations near their extinction threshold are most likely to have an extinction debt. However, as long as a species that is predicted to become extinct still persists, there is time for conservation measures such as habitat restoration and landscape management. Standardized long-term monitoring, more high-quality empirical studies on different taxa and ecosystems and further development of analytical methods will help to better quantify extinction debt and protect biodiversity.

  12. Temporal specificity of extinction in autoshaping.

    Science.gov (United States)

    Drew, Michael R; Yang, Cynthia; Ohyama, Tatsuya; Balsam, Peter D

    2004-07-01

    Three experiments investigated the effects of varying the conditioned stimulus (CS) duration between training and extinction. Ring doves (Streptopelia risoria) were autoshaped on a fixed CS-unconditioned stimulus (US) interval and extinguished with CS presentations that were longer, shorter, or the same as the training duration. During a subsequent test session, the training CS duration was reintroduced. Results suggest that the cessation of responding during an extinction session is controlled by generalization of excitation between the training and extinction CSs and by the number of nonreinforced CS presentations. Transfer of extinction to the training CS is controlled by the similarity between the extinction and training CSs. Extinction learning is temporally specific. (c) 2004 APA, all rights reserved

  13. Light extinction in the atmosphere

    International Nuclear Information System (INIS)

    Laulainen, N.

    1992-06-01

    Atmospheric aerosol particles originating from natural sources, such as volcanos and sulfur-bearing gas emissions from the oceans, and from human sources, such as sulfur emissions from fossil fuel combustion and biomass burning, strongly affect visual air quality and are suspected to significantly affect radiative climate forcing of the planet. During the daytime, aerosols obscure scenic vistas, while at night they diminish our ability to observe stellar objects. Scattering of light is the main means by which aerosols attenuate and redistribute light in the atmosphere and by which aerosols can alter and reduce visibility and potentially modify the energy balance of the planet. Trends and seasonal variability of atmospheric aerosol loading, such as column-integrated light extinction or optical depth, and how they may affect potential climate change have been difficult to quantify because there have been few observations made of important aerosol optical parameters, such as optical depth, over the globe and over time and often these are of uneven quality. To address questions related to possible climate change, there is a pressing need to acquire more high-quality aerosol optical depth data. Extensive deployment of improved solar radiometers over the next few years will provide higher-quality extinction data over a wider variety of locations worldwide. An often overlooked source of turbidity data, however, is available from astronomical observations, particularly stellar photoelectric photometry observations. With the exception of the Project ASTRA articles published almost 20 years ago, few of these data ever appear in the published literature. This paper will review the current status of atmospheric extinction observations, as highlighted by the ASTRA work and augmented by more recent solar radiometry measurements

  14. Sexual selection protects against extinction.

    Science.gov (United States)

    Lumley, Alyson J; Michalczyk, Łukasz; Kitson, James J N; Spurgin, Lewis G; Morrison, Catriona A; Godwin, Joanne L; Dickinson, Matthew E; Martin, Oliver Y; Emerson, Brent C; Chapman, Tracey; Gage, Matthew J G

    2015-06-25

    Reproduction through sex carries substantial costs, mainly because only half of sexual adults produce offspring. It has been theorized that these costs could be countered if sex allows sexual selection to clear the universal fitness constraint of mutation load. Under sexual selection, competition between (usually) males and mate choice by (usually) females create important intraspecific filters for reproductive success, so that only a subset of males gains paternity. If reproductive success under sexual selection is dependent on individual condition, which is contingent to mutation load, then sexually selected filtering through 'genic capture' could offset the costs of sex because it provides genetic benefits to populations. Here we test this theory experimentally by comparing whether populations with histories of strong versus weak sexual selection purge mutation load and resist extinction differently. After evolving replicate populations of the flour beetle Tribolium castaneum for 6 to 7 years under conditions that differed solely in the strengths of sexual selection, we revealed mutation load using inbreeding. Lineages from populations that had previously experienced strong sexual selection were resilient to extinction and maintained fitness under inbreeding, with some families continuing to survive after 20 generations of sib × sib mating. By contrast, lineages derived from populations that experienced weak or non-existent sexual selection showed rapid fitness declines under inbreeding, and all were extinct after generation 10. Multiple mutations across the genome with individually small effects can be difficult to clear, yet sum to a significant fitness load; our findings reveal that sexual selection reduces this load, improving population viability in the face of genetic stress.

  15. Integration of family planning with poverty alleviation.

    Science.gov (United States)

    Peng, P

    1996-12-01

    The Chinese Communist Central Committee and the State Council aim to solve food and clothing problems among impoverished rural people by the year 2000. This goal was a priority on the agenda of the recent October 1996 National Conference on Poverty Alleviation and Development and the 1996 National Conference of the State Family Planning Commission. Poverty is attributed to rapid population growth and underdevelopment. Poverty is concentrated in parts of 18 large provinces. These provinces are characterized by Family Planning Minister Peng as having high birth rates, early marriage and childbearing, unplanned births, and multiple births. Overpopulation is tied to overconsumption, depletion of resources, deforestation, soil erosion, pollution, shortages of water, decreases in shares of cultivated land, degraded grasslands, and general destruction of the environment. Illiteracy in poor areas is over 20%, compared to the national average of 15%. Mortality and morbidity are higher. Family planning is harder to enforce in poor areas. Pilot programs in Sichuan and Guizhou provinces are promoting integration of family planning with poverty alleviation. Several conferences have addressed the integrated program strategies. Experience has shown that poverty alleviation occurs by controlled population growth and improved quality of life. Departments should "consolidate" their development efforts under Communist Party leadership at all levels. Approaches should emphasize self-reliance and public mobilization. The emphasis should be on women's participation in development. Women's income should be increased. Family planning networks at the grassroots level need to be strengthened simultaneously with increased poverty alleviation and development. The government strategy is to strengthen leadership, mobilize the public, and implement integrated programs.

  16. Comment on the extinct paradox

    International Nuclear Information System (INIS)

    Levine, D.M.

    1983-11-01

    The extinction paradox is a contradiction between geometrical optics results which predict that at high frequencies the scattering cross section of an object should equal its geometrical cross section and rigorous scattering theory which shows that at high frequencies the scattering cross section approaches twice the geometrical cross section of the object. Confusion about the reason for this paradox persists today even though the nature of the paradox was correctly identified many years ago by Brillouin. The resolution of the paradox is restated and illustrated with an example, and then the implications to the interpretation of scattering cross sections are identified

  17. Presidential address: distinction or extinction.

    Science.gov (United States)

    Pressman, Barry D

    2008-10-01

    Despite its continuing scientific successes in imaging, radiology as a specialty is faced with a very difficult and competitive environment. Nonradiologists are more and more interested in vertically integrating imaging into their practices, while teleradiology and picture archiving and communication systems are resulting in the greater isolation of radiologists. Commoditization is a realistic and devastating threat to the survival and professionalism of the specialty. To remain viable as a specialty, radiologists must elevate their practice by subspecializing, becoming more involved with clinical care, and actively interacting with patients and referring clinicians. Distinction will prevent extinction.

  18. Methylphenidate enhances extinction of contextual fear

    OpenAIRE

    Abraham, Antony D.; Cunningham, Christopher L.; Lattal, K. Matthew

    2012-01-01

    Methylphenidate (MPH, Ritalin) is a norepinephrine and dopamine transporter blocker that is widely used in humans for treatment of attention deficit disorder and narcolepsy. Although there is some evidence that targeted microinjections of MPH may enhance fear acquisition, little is known about the effect of MPH on fear extinction. Here, we show that MPH, administered before or immediately following extinction of contextual fear, will enhance extinction retention in C57BL/6 mice. Animals that ...

  19. Are Humans too Numerous to Become Extinct?

    OpenAIRE

    Cairns, John

    2009-01-01

    Some claim that humans are too numerous to become extinct. However, passenger pigeon, once the most numerous birds on the planet, are now extinct. For years, humankind has been damaging its habitat, discharging toxic chemicals into the environment, and having harmful effects on agricultural productivity due to climate change. Humankind s extinction depends on the continuation of various human activities including economic growth, addiction to fossil fuel, over consumption, overpopulation, oc...

  20. The Astronomical Pulse of Global Extinction Events

    Directory of Open Access Journals (Sweden)

    David F.V. Lewis

    2006-01-01

    Full Text Available The linkage between astronomical cycles and the periodicity of mass extinctions is reviewed and discussed. In particular, the apparent 26 million year cycle of global extinctions may be related to the motion of the solar system around the galaxy, especially perpendicular to the galactic plane. The potential relevance of Milankovitch cycles is also explored in the light of current evidence for the possible causes of extinction events over a geological timescale.

  1. Differential participation of temporal structures in the consolidation and reconsolidation of taste aversion extinction.

    Science.gov (United States)

    Garcia-Delatorre, Paola; Rodríguez-Ortiz, Carlos J; Balderas, Israela; Bermúdez-Rattoni, Federico

    2010-09-01

    The extinction process has been described as the decline in the frequency or intensity of the conditioned response following the withdrawal of reinforcement. Hence, experimental extinction does not reflect loss of the original memory, but rather reflects new learning, which in turn requires consolidation in order to be maintained in the long term. During extinction of conditioned taste aversion (CTA), a taste previously associated with aversive consequences acquires a safe status through continuous presentations of the flavor with no aversive consequence. In addition, reconsolidation has been defined as the labile state of a consolidated memory after its reactivation by the presentation of relevant information. In this study, we analyzed structures from the temporal lobe that could be involved in consolidation and reconsolidation of extinction of CTA by means of new protein synthesis. Our results showed that protein synthesis in the hippocampus (HC), the perirhinal cortex (PR) and the insular cortex (IC) of rats participate in extinction consolidation, whereas the basolateral amygdala plays no part in this phenomenon. Furthermore, we found that inhibition of protein synthesis in the IC in a third extinction trial had an effect on reconsolidation of extinction. The participation of the HC in taste memory has been described as a downmodulator for CTA consolidation, and has been related to a context-taste association. Altogether, these data suggest that extinction of aversive taste memories are subserved by the IC, HC and PR, and that extinction can undergo reconsolidation, a process depending only on the IC. © 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  2. Long-term maintenance of immediate or delayed extinction is determined by the extinction-test interval

    OpenAIRE

    Johnson, Justin S.; Escobar, Martha; Kimble, Whitney L.

    2010-01-01

    Short acquisition-extinction intervals (immediate extinction) can lead to either more or less spontaneous recovery than long acquisition-extinction intervals (delayed extinction). Using rat subjects, we observed less spontaneous recovery following immediate than delayed extinction (Experiment 1). However, this was the case only if a relatively long extinction-test interval was used; a relatively short extinction-test interval yielded the opposite result (Experiment 2). Previous data appear co...

  3. Intergalactic extinction and the deceleration parameter

    International Nuclear Information System (INIS)

    Meinel, R.

    1981-01-01

    The deceleration parameter q 0 is calculated from the relation between apparent magnitudes m of the brightest galaxies in clusters and their redshifts z considering an intergalactic extinction. The calculation is valid for a Friedman universe, homogeneously filled with dust grains, assuming the extinction to be 0.5 mag at z = 1 and aΛ -1 -law of extinction (according to Oleak and Schmidt 1976). Using the m,z-values of Kristian, Sandage, and Westphal (1978) a formal value of q 0 approximately 2.1 is obtained instead of q 0 approximately 1.6 without consideration of intergalactic extinction. (author)

  4. Interstellar extinction in the Large Magellanic Cloud

    International Nuclear Information System (INIS)

    Nandy, K.; Morgan, D.H.; Willis, A.J.; Wilson, R.; Gondhalekar, P.M.; Houziaux, L.

    1980-01-01

    Recent UV observations together with complementary visible data of several reddened and comparison stars of similar spectral types in the Large Magellanic Cloud have been used to study the interstellar extinction in that galaxy. Most of the reddened stars studied here are located within 2 0 of 30 Doradus and show remarkably high extinction in the far UV, suggesting a large abundance of small particles. From the optical wavelength to 2,600 A the normalised extinction curves of the LMC stars are similar to the mean galactic extinction law. (author)

  5. Mass extinctions vs. uniformitarianism in biological evolution

    Energy Technology Data Exchange (ETDEWEB)

    Bak, P.; Paczuski, M.

    1995-12-31

    It is usually believed that Darwin`s theory leads to a smooth gradual evolution, so that mass extinctions must be caused by external shocks. However, it has recently been argued that mass extinctions arise from the intrinsic dynamics of Darwinian evolution. Species become extinct when swept by intermittent avalanches propagating through the global ecology. These ideas are made concrete through studies of simple mathematical models of co-evolving species. The models exhibit self-organized criticality and describe some general features of the extinction pattern in the fossil record.

  6. Poverty alleviation in Uganda: the case for a viable optimum ...

    African Journals Online (AJOL)

    Poverty alleviation is a long and painstaking process. It involves knowing what poverty is, its causes and means of alleviating it. Poverty is one of the scourges including disease and ignorance a combination of which deprives humanity of the basic needs for living. Among the strategies to alleviate poverty is effective ...

  7. Rural tourism development: a viable formula for poverty alleviation ...

    African Journals Online (AJOL)

    The case of rural tourism and community development has been made in general terms with less focus on poverty alleviation and more emphasis on economic modernisation. Recently, a link between rural tourism and poverty alleviation has been emphasised in the contemporary tourism and poverty alleviation literature.

  8. Anatomical physiology of spatial extinction.

    Science.gov (United States)

    Ciçek, Metehan; Gitelman, Darren; Hurley, Robert S E; Nobre, Anna; Mesulam, Marsel

    2007-12-01

    Neurologically intact volunteers participated in a functional magnetic resonance imaging experiment that simulated the unilateral (focal) and bilateral (global) stimulations used to elicit extinction in patients with hemispatial neglect. In peristriate areas, attentional modulations were selectively sensitive to contralaterally directed attention. A higher level of mapping was observed in the intraparietal sulcus (IPS), inferior parietal lobule (IPL), and inferior frontal gyrus (IFG). In these areas, there was no distinction between contralateral and ipsilateral focal attention, and the need to distribute attention globally led to greater activity than either focal condition. These physiological characteristics were symmetrically distributed in the IPS and IFG, suggesting that the effects of unilateral lesions in these 2 areas can be compensated by the contralateral hemisphere. In the IPL, the greater activation by the bilateral attentional mode was seen only in the right hemisphere. Its contralateral counterpart displayed equivalent activations when attention was distributed to the right, to the left, or bilaterally. Within the context of this experiment, the IPL of the right hemisphere emerged as the one area where unilateral lesions can cause the most uncompensated and selective impairment of global attention (without interfering with unilateral attention to either side), giving rise to the phenomenon of extinction.

  9. Constraints on Enhanced Extinction Resulting from Extinction Treatment in the Presence of an Added Excitor

    Science.gov (United States)

    Urcelay, Gonzalo P.; Lipatova, Olga; Miller, Ralph R.

    2009-01-01

    Three Pavlovian fear conditioning experiments with rats as subjects explored the effect of extinction in the presence of a concurrent excitor. Our aim was to explore this particular treatment, documented in previous studies to deepen extinction, with novel control groups to shed light on the processes involved in extinction. Relative to subjects…

  10. Timing of extinction relative to acquisition: A parametric analysis of fear extinction in humans

    NARCIS (Netherlands)

    Norrholm, S.D.; Vervliet, B.; Jovanovic, T.; Boshoven, W.; Myers, K.M.; Davis, M.; Rothbaum, B.O.; Duncan, E.J.

    2008-01-01

    Fear extinction is a reduction in conditioned fear following repeated exposure to the feared cue in the absence of any aversive event. Extinguished fear often reappears after extinction through spontaneous recovery. Animal studies suggest that spontaneous recovery can be abolished if extinction

  11. Brain oxytocin in social fear conditioning and its extinction: involvement of the lateral septum.

    Science.gov (United States)

    Zoicas, Iulia; Slattery, David A; Neumann, Inga D

    2014-12-01

    Central oxytocin (OXT) has anxiolytic and pro-social properties both in humans and rodents, and has been proposed as a therapeutic option for anxiety and social dysfunctions. Here, we utilized a mouse model of social fear conditioning (SFC) to study the effects of OXT on social fear, and to determine whether SFC causes alterations in central OXT receptor (OXTR) binding and local OXT release. Central infusion of OXT, but not arginine vasopressin, prior to social fear extinction training completely abolished social fear expression in an OXTR-mediated fashion without affecting general anxiety or locomotion. SFC caused increased OXTR binding in the dorso-lateral septum (DLS), central amygdala, dentate gyrus, and cornu ammunis 1, which normalized after social fear extinction, suggesting that these areas form part of a brain network involved in the development and neural support of social fear. Microdialysis revealed that the increase in OXT release observed in unconditioned mice within the DLS during social fear extinction training was attenuated in conditioned mice. Consequently, increasing the availability of local OXT by infusion of OXT into the DLS reversed social fear. Thus, alterations in the brain OXT system, including altered OXTR binding and OXT release within the DLS, play an important role in SFC and social fear extinction. Thus, we suggest that the OXT system is adversely affected in disorders associated with social fear, such as social anxiety disorder and reinstalling an appropriate balance of the OXT system may alleviate some of the symptoms.

  12. Extensive Extinction in Multiple Contexts Eliminates the Renewal of Conditioned Fear in Rats

    Science.gov (United States)

    Thomas, Brian L.; Vurbic, Drina; Novak, Cheryl

    2009-01-01

    Two studies examined whether nonreinforcement of a stimulus in multiple contexts, instead of a single context, would decrease renewal of conditioned fear in rats (as assessed by conditioned suppression of lever pressing). In Experiment 1, renewal was measured after 36 nonreinforced CS trials delivered during six extinction sessions in a single…

  13. Long-Term Maintenance of Immediate or Delayed Extinction Is Determined by the Extinction-Test Interval

    Science.gov (United States)

    Johnson, Justin S.; Escobar, Martha; Kimble, Whitney L.

    2010-01-01

    Short acquisition-extinction intervals (immediate extinction) can lead to either more or less spontaneous recovery than long acquisition-extinction intervals (delayed extinction). Using rat subjects, we observed less spontaneous recovery following immediate than delayed extinction (Experiment 1). However, this was the case only if a relatively…

  14. Docosahexaenoic Acid Helps to Lessen Extinction Memory in Rats

    Directory of Open Access Journals (Sweden)

    Michio Hashimoto

    2018-02-01

    Full Text Available Abstract: Memory extinction is referred to as a learning process in which a conditioned response (CR progressively reduces over time as an animal learns to uncouple a response from a stimulus. Extinction occurs when the rat is placed into a context without shock after training. Docosahexaenoic acid (DHA, C22:6, n-3 is implicated in memory formation in mammalian brains. In a two-way active shuttle-avoidance apparatus, we examined whether DHA affects the extinction memory and the expression of brain cognition-related proteins, including gastrin-releasing peptide receptor (GRPR, brain-derived neurotrophic factor receptor (BDNFR tyrosine kinase receptor B (TrKB, and N-methyl-d-aspartate receptor (NMDAR subunits NR2A and NR2B. Also, the protein levels of GRP, BDNF, postsynaptic density protein-95 (PSD-95, and vesicular acetylcholine transporter (VAChT, and the antioxidative potentials, in terms of lipid peroxide (LPO and reactive oxygen species (ROS, were examined in the hippocampus. During the acquisition phase, the rats received a conditioned stimulus (CS-tone paired with an unconditioned stimulus (UCS foot shock for three consecutive days (Sessions S1, S2, and S3, each consisting of 30-trials after 12 weeks of oral administration of DHA. After a three-day interval, the rats were re-subjected to two extinction sessions (S4, S5, each comprising 30 trials of CS alone. During the acquisition training in S1, the shock-related avoidance frequency (acquisition memory was significantly higher in the DHA-administered rats compared with the control rats. The avoidance frequency, however, decreased with successive acquisition trainings in sessions S2 and S3. When the rats were subjected to the extinction sessions after a break for consolidation, the conditioned response (CR was also significantly higher in the DHA-administered rats. Interestingly, the freezing responses (frequency and time also significantly decreased in the DHA-administered rats, thus

  15. Can Parallelingualism Save Norwegian from Extinction?

    Science.gov (United States)

    Linn, Andrew R.

    2010-01-01

    Language extinction is one of the most pressing issues in linguistics today, and the literature is full of discussion about how to combat it. Statements that Norwegian is amongst the languages that are already extinct are merely examples of a widespread tendency in the literature towards erroneous information about Norwegian. Nonetheless, there is…

  16. Evaluating herbivore extinction probabilities in Addo Elephant ...

    African Journals Online (AJOL)

    Abstract. Population extinction evaluations, based on the model developed by Dennis et al. (1991) that did not take density dependence into account and that were based on census data, suggest that many of the herbivore species in Addo Elephant National Park (AENP) are vulnerable to local extinction. As a result of low ...

  17. Extinction-Induced Variability in Human Behavior

    Science.gov (United States)

    Kinloch, Jennifer M.; Foster, T. Mary; McEwan, James S. A.

    2009-01-01

    Participants earned points by pressing a computer space bar (Experiment 1) or forming rectangles on the screen with the mouse (Experiment 2) under differential-reinforcement-of-low-rate schedules, followed by extinction. Variability in interresponse time (the contingent dimension) increased during extinction, as for Morgan and Lee (1996);…

  18. Context and Behavioral Processes in Extinction

    Science.gov (United States)

    Bouton, Mark E.

    2004-01-01

    This article provides a selective review and integration of the behavioral literature on Pavlovian extinction. The first part reviews evidence that extinction does not destroy the original learning, but instead generates new learning that is especially context-dependent. The second part examines insights provided by research on several related…

  19. Current extinction rates of reptiles and amphibians.

    Science.gov (United States)

    Alroy, John

    2015-10-20

    There is broad concern that a mass extinction of amphibians and reptiles is now underway. Here I apply an extremely conservative Bayesian method to estimate the number of recent amphibian and squamate extinctions in nine important tropical and subtropical regions. The data stem from a combination of museum collection databases and published site surveys. The method computes an extinction probability for each species by considering its sighting frequency and last sighting date. It infers hardly any extinction when collection dates are randomized and it provides underestimates when artificial extinction events are imposed. The method also appears to be insensitive to trends in sampling; therefore, the counts it provides are absolute minimums. Extinctions or severe population crashes have accumulated steadily since the 1970s and 1980s, and at least 3.1% of frog species have already disappeared. Based on these data and this conservative method, the best estimate of the global grand total is roughly 200 extinctions. Consistent with previous results, frog losses are heavy in Latin America, which has been greatly affected by the pathogenic chytrid fungus Batrachochytrium dendrobatidis. Extinction rates are now four orders-of-magnitude higher than background, and at least another 6.9% of all frog species may be lost within the next century, even if there is no acceleration in the growth of environmental threats.

  20. Lidar extinction measurement in the mid infrared

    Science.gov (United States)

    Mitev, Valentin; Babichenko, S.; Borelli, R.; Fiorani, L.; Grigorov, I.; Nuvoli, M.; Palucci, A.; Pistilli, M.; Puiu, Ad.; Rebane, Ott; Santoro, S.

    2014-11-01

    We present a lidar measurement of atmospheric extinction coefficient. The measurement is performed by inversion of the backscatter lidar signal at wavelengths 3'000nm and 3'500nm. The inversion of the backscatter lidar signal was performed with constant extinction-to-backscatter ration values of 104 and exponential factor 0.1.

  1. Interstellar extinction in the Large Magellanic Cloud

    International Nuclear Information System (INIS)

    Nandy, K.; Morgan, D.H.; Willis, A.J.; Wilson, R.; Gondhalekar, P.M.

    1981-01-01

    A systematic investigation of interstellar extinction in the ultraviolet as a function of position in the Large Magellanic Cloud has been made from an enlarged sample of reddened and comparison stars distributed throughout the cloud. Except for one star SK-69-108, the most reddened star of our sample, the shape of the extinction curves for the LMC stars do not show significant variations. All curves show an increase in extinction towards 2200 A, but some have maxima near 2200 A, some near 1900 A. It has been shown that the feature of the extinction curve near 1900 A is caused by the mismatch of the stellar F III 1920 A feature. The strength of this 1920 A feature as a function of luminosity and spectral type has been determined. The extinction curves have been corrected for the mismatch of the 1920 feature and a single mean extinction curve for the LMC normalized to Asub(V) = 0 and Esub(B-V) = 1 is presented. For the same value of Esub(B-V) the LMC stars show the 2200 A feature weaker by a factor 2 as compared with the galactic stars. Higher extinction shortward of 2000 A in the LMC extinction curves than that in our Galaxy, as reported in earlier papers, is confirmed. (author)

  2. Enhancing Divergent Search through Extinction Events

    DEFF Research Database (Denmark)

    Lehman, Joel; Miikkulainen, Risto

    2015-01-01

    for the capacity to evolve. This hypothesis is tested through experiments in two evolutionary robotics domains. The results show that combining extinction events with divergent search increases evolvability, while combining them with convergent search offers no similar benefit. The conclusion is that extinction...

  3. Mass extinctions: Ecological selectivity and primary production

    Science.gov (United States)

    Rhodes, Melissa Clark; Thayer, Charles W.

    1991-09-01

    If mass extinctions were caused by reduced primary productivity, then extinctions should be concentrated among animals with starvation-susceptible feeding modes, active lifestyles, and high-energy budgets. The stratigraphic ranges (by stage) of 424 genera of bivalves and 309 genera of articulate brachiopods suggest that there was an unusual reduction of primary productivity at the Cretaceous/Tertiary (K/T) boundary extinction. For bivalves at the K/T, there were (1) selective extinction of suspension feeders and other susceptible trophic categories relative to deposit feeders and other resistant categories, and (2) among suspension feed-ers, selective extinction of bivalves with active locomotion. During the Permian-Triassic (P/Tr) extinction and Jurassic background time, extinction rates among suspension feeders were greater for articulate brachiopods than for bivalves. But during the K/T event, extinction rates of articulates and suspension-feeding bivalves equalized, possibly because the low-energy budgets of articulates gave them an advantage when food was scarce.

  4. Defining the period of moa extinction

    International Nuclear Information System (INIS)

    Anderson, A.

    2000-01-01

    Few aspects of New Zealand's prehistory have engaged scientific and public attention so consistently as two interlinked questions of moa extinction; when did moas become extinct and why? Answers offered over the last 160 years have run the gamut from chronological antiquity by evolutionary senescence, to within the 19th century Maori and European disturbance. (author)

  5. Immediate extinction promotes the return of fear.

    Science.gov (United States)

    Merz, Christian J; Hamacher-Dang, Tanja C; Wolf, Oliver T

    2016-05-01

    Accumulating evidence indicates that immediate extinction is less effective than delayed extinction in attenuating the return of fear. This line of fear conditioning research impacts the proposed onset of psychological interventions after threatening situations. In the present study, forty healthy men were investigated in a differential fear conditioning paradigm with fear acquisition in context A, extinction in context B, followed by retrieval testing in both contexts 24h later to test fear renewal. Differently coloured lights served as conditioned stimuli (CS): two CS (CS+) were paired with an electrical stimulation that served as unconditioned stimulus, the third CS was never paired (CS-). Extinction took place immediately after fear acquisition or 24h later. One CS+ was extinguished whereas the second CS+ remained unextinguished to control for different time intervals between fear acquisition and retrieval testing. Immediate extinction led to larger skin conductance responses during fear retrieval to both the extinguished and unextinguished CS relative to the CS-, indicating a stronger return of fear compared to delayed extinction. Taken together, immediate extinction is less potent than delayed extinction and is associated with a stronger renewal effect. Thus, the time-point of psychological interventions relative to the offset of threatening situations needs to be carefully considered to prevent relapses. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Mass extinction in poorly known taxa.

    Science.gov (United States)

    Régnier, Claire; Achaz, Guillaume; Lambert, Amaury; Cowie, Robert H; Bouchet, Philippe; Fontaine, Benoît

    2015-06-23

    Since the 1980s, many have suggested we are in the midst of a massive extinction crisis, yet only 799 (0.04%) of the 1.9 million known recent species are recorded as extinct, questioning the reality of the crisis. This low figure is due to the fact that the status of very few invertebrates, which represent the bulk of biodiversity, have been evaluated. Here we show, based on extrapolation from a random sample of land snail species via two independent approaches, that we may already have lost 7% (130,000 extinctions) of the species on Earth. However, this loss is masked by the emphasis on terrestrial vertebrates, the target of most conservation actions. Projections of species extinction rates are controversial because invertebrates are essentially excluded from these scenarios. Invertebrates can and must be assessed if we are to obtain a more realistic picture of the sixth extinction crisis.

  7. Assessing Extinction Risk: Integrating Genetic Information

    Directory of Open Access Journals (Sweden)

    Jason Dunham

    1999-06-01

    Full Text Available Risks of population extinction have been estimated using a variety of methods incorporating information from different spatial and temporal scales. We briefly consider how several broad classes of extinction risk assessments, including population viability analysis, incidence functions, and ranking methods integrate information on different temporal and spatial scales. In many circumstances, data from surveys of neutral genetic variability within, and among, populations can provide information useful for assessing extinction risk. Patterns of genetic variability resulting from past and present ecological and demographic events, can indicate risks of extinction that are otherwise difficult to infer from ecological and demographic analyses alone. We provide examples of how patterns of neutral genetic variability, both within, and among populations, can be used to corroborate and complement extinction risk assessments.

  8. Climate predictors of late quaternary extinctions

    DEFF Research Database (Denmark)

    Nogués-Bravo, David; Ohlemüller, Ralf; Batra, Persaram

    2010-01-01

    Between 50,000 and 3,000 years before present (BP) 65% of mammal genera weighing over 44 kg went extinct, together with a lower proportion of small mammals. Why species went extinct in such large numbers is hotly debated. One of the arguments proposes that climate changes underlie Late Quaternary...... extinctions, but global quantitative evidence for this hypothesis is still lacking. We test the potential role of global climate change on the extinction of mammals during the Late Quaternary. Our results suggest that continents with the highest climate footprint values, in other words, with climate changes...... of greater magnitudes during the Late Quaternary, witnessed more extinctions than continents with lower climate footprint values, with the exception of South America. Our results are consistent across species with different body masses, reinforcing the view that past climate changes contributed to global...

  9. A phantom extinction? New insights into extinction dynamics of the Don-hare Lepus tanaiticus.

    Science.gov (United States)

    Prost, S; Knapp, M; Flemmig, J; Hufthammer, A K; Kosintsev, P; Stiller, M; Hofreiter, M

    2010-09-01

    The Pleistocene to Holocene transition was accompanied by a worldwide extinction event affecting numerous mammalian species. Several species such as the woolly mammoth and the giant deer survived this extinction wave, only to go extinct a few thousand years later during the Holocene. Another example for such a Holocene extinction is the Don-hare, Lepus tanaiticus, which inhabited the Russian plains during the late glacial. After being slowly replaced by the extant mountain hare (Lepus timidus), it eventually went extinct during the middle Holocene. Here, we report the phylogenetic relationship of L. tanaiticus and L. timidus based on a 339-basepair (bp) fragment of the mitochondrial D-loop. Phylogenetic tree- and network reconstructions do not support L. tanaiticus and L. timidus being different species. Rather, we suggest that the two taxa represent different morphotypes of a single species and the extinction of 'L. tanaiticus' represents the disappearance of a local morphotype rather than the extinction of a species.

  10. Trophic redundancy reduces vulnerability to extinction cascades.

    Science.gov (United States)

    Sanders, Dirk; Thébault, Elisa; Kehoe, Rachel; Frank van Veen, F J

    2018-03-06

    Current species extinction rates are at unprecedentedly high levels. While human activities can be the direct cause of some extinctions, it is becoming increasingly clear that species extinctions themselves can be the cause of further extinctions, since species affect each other through the network of ecological interactions among them. There is concern that the simplification of ecosystems, due to the loss of species and ecological interactions, increases their vulnerability to such secondary extinctions. It is predicted that more complex food webs will be less vulnerable to secondary extinctions due to greater trophic redundancy that can buffer against the effects of species loss. Here, we demonstrate in a field experiment with replicated plant-insect communities, that the probability of secondary extinctions is indeed smaller in food webs that include trophic redundancy. Harvesting one species of parasitoid wasp led to secondary extinctions of other, indirectly linked, species at the same trophic level. This effect was markedly stronger in simple communities than for the same species within a more complex food web. We show that this is due to functional redundancy in the more complex food webs and confirm this mechanism with a food web simulation model by highlighting the importance of the presence and strength of trophic links providing redundancy to those links that were lost. Our results demonstrate that biodiversity loss, leading to a reduction in redundant interactions, can increase the vulnerability of ecosystems to secondary extinctions, which, when they occur, can then lead to further simplification and run-away extinction cascades. Copyright © 2018 the Author(s). Published by PNAS.

  11. Direction of attention bias to threat relates to differences in fear acquisition and extinction in anxious children.

    Science.gov (United States)

    Waters, Allison M; Kershaw, Rachel

    2015-01-01

    Anxious children show attention biases towards and away from threat stimuli. Moreover, threat avoidance compared to vigilance predicts a poorer outcome from exposure-based treatments, such as cognitive-behavioural therapy (CBT), yet the mechanisms underlying this differential response are unclear. Pavlovian fear conditioning is a widely accepted theory to explain the acquisition and extinction of fear, including exposure-based treatments, such as CBT. In typical fear conditioning experiments, anxious children have shown larger physiological responses to an aversive unconditional stimulus (i.e., US on CS+ trials) and to non-reinforced stimuli (CS-) during fear acquisition and to both CSs during fear extinction compared to non-anxious peers. This study examined whether threat avoidance compared to threat vigilance was related to differences in fear acquisition and extinction in anxious children. Thirty-four clinically-anxious children completed a visual probe task including angry-neutral face pairs to determine the direction of threat attention bias as well as a discriminant conditioning and extinction task in which a geometric shape CS+ was paired with an aversive tone US, while the CS- geometric shape was always presented alone during acquisition trials. Both CSs were presented alone during extinction trials. Fear acquisition and extinction were indexed by skin conductance responses (SCR) and subjective measures. Children were classified as threat vigilant (N = 18) and threat avoidant (n = 16) based on the direction of threat attention bias on the visual probe task. During acquisition, threat avoidant relative to threat vigilant anxious children displayed larger orienting SCRs to both CSs during the first block of trials and larger third interval SCRs to the US on CS+ trials as well as on CS- trials. During extinction, threat avoidant anxious children showed delayed extinction of SCRs to both the CS+ and CS- and reported higher subjective anxiety ratings after

  12. Immediate extinction causes a less durable loss of performance than delayed extinction following either fear or appetitive conditioning

    OpenAIRE

    Woods, Amanda M.; Bouton, Mark E.

    2008-01-01

    Five experiments with rat subjects compared the effects of immediate and delayed extinction on the durability of extinction learning. Three experiments examined extinction of fear conditioning (using the conditioned emotional response method), and two experiments examined extinction of appetitive conditioning (using the food-cup entry method). In all experiments, conditioning and extinction were accomplished in single sessions, and retention testing took place 24 h after extinction. In both f...

  13. Soil stabilization field trial : interim report II.

    Science.gov (United States)

    2002-02-01

    Shrinkage cracks in cement-stabilized bases/subbase can be alleviated by specifying the right cement dosage, or by other additives/procedures that suppress crack susceptibility. A field trial of six 1000 ft sections to investigate several alternative...

  14. Extinction produces context inhibition and multiple-context extinction reduces response recovery in human predictive learning.

    Science.gov (United States)

    Glautier, Steven; Elgueta, Tito; Nelson, James Byron

    2013-12-01

    Two experiments with human participants were used to investigate recovery of an extinguished learned response after a context change using ABC designs. In an ABC design, the context changes over the three successive stages of acquisition (context A), extinction (context B), and test (context C). In both experiments, we found reduced recovery in groups that had extinction in multiple contexts, and that the extinction contexts acquired inhibitory strength. These results confirm those of previous investigations, that multiple-context extinction can produce less response recovery than single-context extinction, and they also provide new evidence for the involvement of contextual inhibitory processes in extinction in humans. The foregoing results are broadly in line with a protection-from-extinction account of response recovery. Yet, despite the fact that we detected contextual inhibition, predictions based on protection-from-extinction were not fully reliable for the single- and multiple-context group differences that we observed in (1) rates of extinction and (2) the strength of context inhibition. Thus, although evidence was obtained for a protection-from-extinction account of response recovery, this account can not explain all of the data.

  15. Estimating extinction using unsupervised machine learning

    Science.gov (United States)

    Meingast, Stefan; Lombardi, Marco; Alves, João

    2017-05-01

    Dust extinction is the most robust tracer of the gas distribution in the interstellar medium, but measuring extinction is limited by the systematic uncertainties involved in estimating the intrinsic colors to background stars. In this paper we present a new technique, Pnicer, that estimates intrinsic colors and extinction for individual stars using unsupervised machine learning algorithms. This new method aims to be free from any priors with respect to the column density and intrinsic color distribution. It is applicable to any combination of parameters and works in arbitrary numbers of dimensions. Furthermore, it is not restricted to color space. Extinction toward single sources is determined by fitting Gaussian mixture models along the extinction vector to (extinction-free) control field observations. In this way it becomes possible to describe the extinction for observed sources with probability densities, rather than a single value. Pnicer effectively eliminates known biases found in similar methods and outperforms them in cases of deep observational data where the number of background galaxies is significant, or when a large number of parameters is used to break degeneracies in the intrinsic color distributions. This new method remains computationally competitive, making it possible to correctly de-redden millions of sources within a matter of seconds. With the ever-increasing number of large-scale high-sensitivity imaging surveys, Pnicer offers a fast and reliable way to efficiently calculate extinction for arbitrary parameter combinations without prior information on source characteristics. The Pnicer software package also offers access to the well-established Nicer technique in a simple unified interface and is capable of building extinction maps including the Nicest correction for cloud substructure. Pnicer is offered to the community as an open-source software solution and is entirely written in Python.

  16. Amount of fear extinction changes its underlying mechanisms.

    Science.gov (United States)

    An, Bobae; Kim, Jihye; Park, Kyungjoon; Lee, Sukwon; Song, Sukwoon; Choi, Sukwoo

    2017-07-03

    There has been a longstanding debate on whether original fear memory is inhibited or erased after extinction. One possibility that reconciles this uncertainty is that the inhibition and erasure mechanisms are engaged in different phases (early or late) of extinction. In this study, using single-session extinction training and its repetition (multiple-session extinction training), we investigated the inhibition and erasure mechanisms in the prefrontal cortex and amygdala of rats, where neural circuits underlying extinction reside. The inhibition mechanism was prevalent with single-session extinction training but faded when single-session extinction training was repeated. In contrast, the erasure mechanism became prevalent when single-session extinction training was repeated. Moreover, ablating the intercalated neurons of amygdala, which are responsible for maintaining extinction-induced inhibition, was no longer effective in multiple-session extinction training. We propose that the inhibition mechanism operates primarily in the early phase of extinction training, and the erasure mechanism takes over after that.

  17. Fear acquisition and extinction in offspring of mothers with anxiety and depressive disorders.

    Science.gov (United States)

    Waters, Allison M; Peters, Rosie-Mae; Forrest, Kylee E; Zimmer-Gembeck, Melanie

    2014-01-01

    Maternal anxiety and depression are significant risk factors for the development of these disorders in offspring. The pathways through which risk is conferred remain unclear. This study examined fear acquisition and extinction in 26 children at high risk for emotional disorders by virtue of maternal psychopathology (n=14 with a mother with a principal anxiety disorder and n=12 with a mother with a principal unipolar depressive disorder) and 31 low risk controls using a discriminative Pavlovian conditioning procedure. Participants, aged between 7 and 14 years, completed 16 trials of discriminative conditioning of two geometric figures, with (CS+) and without (CS-) an aversive tone (US), followed by 8 extinction trials (4×CS+, 4×CS-). In the context of comparable discriminative conditioning, children of anxious mothers showed larger skin conductance responses during extinction to the CS+ compared to the CS-, and to both CSs from the first to the second block of extinction trials, in comparison with low risk controls. Compared to low risk controls, children of depressed mothers showed smaller skin conductance responses to the CS+ than the CS- during acquisition. These findings suggest distinct psychophysiological premorbid risk markers in offspring of anxious and depressed mothers. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Vicuña conservation and poverty alleviation? Andean communities and international fibre markets

    Directory of Open Access Journals (Sweden)

    Gabriela Lichtenstein

    2009-09-01

    Full Text Available Vicuna (Vicugna vicugna fiber is produced by extremely low-income communities that inhabit the harsh environment of the Andes in Argentina, Chile, Peru and Bolivia. At the other end of the social scale, affluent consumers are willing to pay high prices for vicuna-made accessories and clothes. Vicuna management projects follow the logic of community-based wildlife management. The rationale for seeking to conserve vicuñas through sustainable use is that commercial utilization of the fiber (obtained from live-shorn animals will generate sufficient economic benefits to outweigh the costs of conservation, and contribute to community development and poverty alleviation. However, although conservation efforts have been extremely successful with vicuñas having recovered from the brink of extinction, the socio-economic achievements have thus far proved modest. This paper explores multiple-objective projects that address vicuña conservation and poverty alleviation in Andean countries. In doing so it analyses the tensions that exist between these objectives, as well as the factors that limit a more equitable distribution of benefits among stakeholders. Examples are drawn from vicuna management under common-property in Peru and Bolivia, and vicuna captive management under private property in Argentina. These case studies enable us to illustrate the complex relationship between local communities and the global market, and the importance of community enterprises and supportive government policy in managing a common pool resource.

  19. Rainwater harvesting for drought disaster alleviation

    International Nuclear Information System (INIS)

    Widodo, B.; Prinzand, D.; Malik, A.H.

    2005-01-01

    Too little water and too much water can be as devastating as well. Drought usually does not show up instantly like flood, but it creeps slowly. Drought that is less popular than flood has impact more serious than flood. It is difficult to be identified when it comes and when it goes away. However, it is suddenly understood when water becomes scare, or no more water is available in wells, rivers and reservoirs. Managing flood and drought has to be at an integrated basis. Rainwater harvesting (RWH) combined with water conservation methods can be developed to alleviate drought disaster as well as flood disaster in the same time. RWH and water conservation must be an integral part of integrated water resources management. Preventing drought could be automatically reducing the extent of flood that means preventing people and the environment from the disasters. (author)

  20. Alleviate Cellular Congestion Through Opportunistic Trough Filling

    Directory of Open Access Journals (Sweden)

    Yichuan Wang

    2014-04-01

    Full Text Available The demand for cellular data service has been skyrocketing since the debut of data-intensive smart phones and touchpads. However, not all data are created equal. Many popular applications on mobile devices, such as email synchronization and social network updates, are delay tolerant. In addition, cellular load varies significantly in both large and small time scales. To alleviate network congestion and improve network performance, we present a set of opportunistic trough filling schemes that leverage the time-variation of network congestion and delay-tolerance of certain traffic in this paper. We consider average delay, deadline, and clearance time as the performance metrics. Simulation results show promising performance improvement over the standard schemes. The work shed lights on addressing the pressing issue of cellular overload.

  1. Hospital autopsy: Endangered or extinct?

    Science.gov (United States)

    Turnbull, Angus; Osborn, Michael; Nicholas, Nick

    2015-08-01

    To determine the hospital autopsy rate for the UK in 2013. A study of data from a 'Freedom of Information' request to all (n=186) acute NHS Trusts within England (n=160), NHS Boards in Scotland (n=14) and Wales (n=7) and Social Care Trusts in Northern Ireland (n=5). Hospital autopsy rates were calculated from the number of hospital autopsies performed in 2013 as a percentage of total inpatient deaths in the Trust that year. The UK response rate was 99% (n=184), yielding a mean autopsy rate of 0.69%. The mean rates were 0.51% (England), 2.13% (Scotland), 0.65% (Wales) and 0.46% (Northern Ireland). 23% (n=38) of all included respondents had a rate of 0% and 86% (n=143) a rate less than 1%. The decline in hospital autopsy has continued relentlessly and, for better or for worse, the practice is on the verge of extinction in the UK. The study highlights to health professionals and policy makers the magnitude of this decline. Further research should investigate the impact of this on patient safety, clinical audit, public health and medical education. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  2. Extinction from a rationalist perspective.

    Science.gov (United States)

    Gallistel, C R

    2012-05-01

    The merging of the computational theory of mind and evolutionary thinking leads to a kind of rationalism, in which enduring truths about the world have become implicit in the computations that enable the brain to cope with the experienced world. The dead reckoning computation, for example, is implemented within the brains of animals as one of the mechanisms that enables them to learn where they are (Gallistel, 1990, 1995). It integrates a velocity signal with respect to a time signal. Thus, the manner in which position and velocity relate to one another in the world is reflected in the manner in which signals representing those variables are processed in the brain. I use principles of information theory and Bayesian inference to derive from other simple principles explanations for: (1) the failure of partial reinforcement to increase reinforcements to acquisition; (2) the partial reinforcement extinction effect; (3) spontaneous recovery; (4) renewal; (5) reinstatement; (6) resurgence (aka facilitated reacquisition). Like the principle underlying dead-reckoning, these principles are grounded in analytic considerations. They are the kind of enduring truths about the world that are likely to have shaped the brain's computations. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Intercessory prayer for the alleviation of ill health.

    Science.gov (United States)

    Roberts, Leanne; Ahmed, Irshad; Hall, Steve; Davison, Andrew

    2009-04-15

    Prayer is amongst the oldest and most widespread interventions used with the intention of alleviating illness and promoting good health. Given the significance of this response to illness for a large proportion of the world's population, there has been considerable interest in recent years in measuring the efficacy of intercessory prayer for the alleviation of ill health in a scientifically rigorous fashion. The question of whether this may contribute towards proving or disproving the existence of God is a philosophical question lying outside the scope of this review of the effects of prayer. This revised version of the review has been prepared in response to feedback and to reflect new methods in the conduct and presentation of Cochrane reviews. To review the effects of intercessory prayer as an additional intervention for people with health problems already receiving routine health care. We systematically searched ten relevant databases including MEDLINE and EMBASE (June 2007). We included any randomised trial comparing personal, focused, committed and organised intercessory prayer with those interceding holding some belief that they are praying to God or a god versus any other intervention. This prayer could be offered on behalf of anyone with health problems. We extracted data independently and analysed it on an intention to treat basis, where possible. We calculated, for binary data, the fixed-effect relative risk (RR), their 95% confidence intervals (CI), and the number needed to treat or harm (NNT or NNH). Ten studies are included in this updated review (7646 patients). For the comparison of intercessory prayer plus standard care versus standard care alone, overall there was no clear effect of intercessory prayer on death, with the effect not reaching statistical significance and data being heterogeneous (6 RCTs, n=6784, random-effects RR 0.77 CI 0.51 to 1.16, I(2) 83%). For general clinical state there was also no significant difference between groups (5

  4. Stress before extinction learning enhances and generalizes extinction memory in a predictive learning task.

    Science.gov (United States)

    Meir Drexler, Shira; Hamacher-Dang, Tanja C; Wolf, Oliver T

    2017-05-01

    In extinction learning, the individual learns that a previously acquired association (e.g. between a threat and its predictor) is no longer valid. This learning is the principle underlying many cognitive-behavioral psychotherapeutic treatments, e.g. 'exposure therapy'. However, extinction is often highly-context dependent, leading to renewal (relapse of extinguished conditioned response following context change). We have previously shown that post-extinction stress leads to a more context-dependent extinction memory in a predictive learning task. Yet as stress prior to learning can impair the integration of contextual cues, here we aim to create a more generalized extinction memory by inducing stress prior to extinction. Forty-nine men and women learned the associations between stimuli and outcomes in a predictive learning task (day 1), extinguished them shortly after an exposure to a stress/control condition (day 2), and were tested for renewal (day 3). No group differences were seen in acquisition and extinction learning, and a renewal effect was present in both groups. However, the groups differed in the strength and context-dependency of the extinction memory. Compared to the control group, the stress group showed an overall reduced recovery of responding to the extinguished stimuli, in particular in the acquisition context. These results, together with our previous findings, demonstrate that the effects of stress exposure on extinction memory depend on its timing. While post-extinction stress makes the memory more context-bound, pre-extinction stress strengthens its consolidation for the acquisition context as well, making it potentially more resistant to relapse. These results have implications for the use of glucocorticoids as extinction-enhancers in exposure therapy. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Interstellar extinction in the Small Magellanic Cloud

    International Nuclear Information System (INIS)

    Nandy, K.; McLachlan, A.; Thompson, G.I.; Morgan, D.H.; Willis, A.J.; Wilson, R.; Gondhalekar, P.M.; Houziaux, L.

    1982-01-01

    IUE observations of three considerably reddened stars located near the core of the Small Magellanic Cloud and of two comparison stars which are also SMC members are presented. This region contains a considerable amount of dust. The UV spectrum of one of the reddened stars (BBB 338) shows the lambda 2200 feature characteristic of the Galactic extinction curve. This absorption feature is not obvious in the UV spectra of the other two reddened stars. Due to lack of a suitable comparison star it has not been possible to measure the UV extinction of BBB 338. The extinction curves derived for the other two reddened SMC members differ from the mean Galactic law in that they exhibit very weak or absent lambda 2200 and much higher values of far-UV extinction. These differences are greater than have been found for stars in the Large Magellanic Cloud, confirming earlier observations by others. (author)

  6. Anthropogenic stressors and riverine fish extinctions

    NARCIS (Netherlands)

    Dias, M.S.; Tedesco, P.A.; Hugueny, B.; Jézéquel, C.; Beauchard, O.; Brosse, S.; Oberdorff, T.

    2017-01-01

    Human activities are often implicated in the contemporary extinction of contemporary species. Concerningriverine fishes, the major biotic and abiotic threats widely cited include introduction of non-nativespecies, habitat fragmentation and homogenization in stream flow dynamics due to the damming

  7. Are marine and nonmarine extinctions correlated?

    Science.gov (United States)

    Rampino, Michael R.

    Recent papers in Eos have debated the possible relationships between marine mass extinctions, comet showers, and volcanism [Alvarez, 1986; Officer and Grieve, 1986], and ail three might be linked [Rampino, 1987]. Moreover, as Officer and Grieve [ 1986] point out, various other causes have been suggested for given extinction events, including changes in climate, ocean circulation, and sea level fluctuations, possibly related to plate tectonics and continental positions. Also under debate is the issue of whether mass extinctions were gradual, stepped, or geologically sudden events (see, for example, Hut et al. [1987]). A missing ingredient thus far in these debates has been the record of faunal diversity of nonmarine animals. Does this show any agreement with the marine extinction record?

  8. Extinction vulnerability of coral reef fishes.

    Science.gov (United States)

    Graham, Nicholas A J; Chabanet, Pascale; Evans, Richard D; Jennings, Simon; Letourneur, Yves; Aaron Macneil, M; McClanahan, Tim R; Ohman, Marcus C; Polunin, Nicholas V C; Wilson, Shaun K

    2011-04-01

    With rapidly increasing rates of contemporary extinction, predicting extinction vulnerability and identifying how multiple stressors drive non-random species loss have become key challenges in ecology. These assessments are crucial for avoiding the loss of key functional groups that sustain ecosystem processes and services. We developed a novel predictive framework of species extinction vulnerability and applied it to coral reef fishes. Although relatively few coral reef fishes are at risk of global extinction from climate disturbances, a negative convex relationship between fish species locally vulnerable to climate change vs. fisheries exploitation indicates that the entire community is vulnerable on the many reefs where both stressors co-occur. Fishes involved in maintaining key ecosystem functions are more at risk from fishing than climate disturbances. This finding is encouraging as local and regional commitment to fisheries management action can maintain reef ecosystem functions pending progress towards the more complex global problem of stabilizing the climate. © 2011 Blackwell Publishing Ltd/CNRS.

  9. Edaravone alleviates Alzheimer's disease-type pathologies and cognitive deficits.

    Science.gov (United States)

    Jiao, Shu-Sheng; Yao, Xiu-Qing; Liu, Yu-Hui; Wang, Qing-Hua; Zeng, Fan; Lu, Jian-Jun; Liu, Jia; Zhu, Chi; Shen, Lin-Lin; Liu, Cheng-Hui; Wang, Ye-Ran; Zeng, Gui-Hua; Parikh, Ankit; Chen, Jia; Liang, Chun-Rong; Xiang, Yang; Bu, Xian-Le; Deng, Juan; Li, Jing; Xu, Juan; Zeng, Yue-Qin; Xu, Xiang; Xu, Hai-Wei; Zhong, Jin-Hua; Zhou, Hua-Dong; Zhou, Xin-Fu; Wang, Yan-Jiang

    2015-04-21

    Alzheimer's disease (AD) is one of most devastating diseases affecting elderly people. Amyloid-β (Aβ) accumulation and the downstream pathological events such as oxidative stress play critical roles in pathogenesis of AD. Lessons from failures of current clinical trials suggest that targeting multiple key pathways of the AD pathogenesis is necessary to halt the disease progression. Here we show that Edaravone, a free radical scavenger that is marketed for acute ischemic stroke, has a potent capacity of inhibiting Aβ aggregation and attenuating Aβ-induced oxidation in vitro. When given before or after the onset of Aβ deposition via i.p. injection, Edaravone substantially reduces Aβ deposition, alleviates oxidative stress, attenuates the downstream pathologies including Tau hyperphosphorylation, glial activation, neuroinflammation, neuronal loss, synaptic dysfunction, and rescues the behavioral deficits of APPswe/PS1 mice. Oral administration of Edaravone also ameliorates the AD-like pathologies and memory deficits of the mice. These findings suggest that Edaravone holds a promise as a therapeutic agent for AD by targeting multiple key pathways of the disease pathogenesis.

  10. Interstellar Silicon Depletion and the Ultraviolet Extinction

    Science.gov (United States)

    Mishra, Ajay; Li, Aigen

    2018-01-01

    Spinning small silicate grains were recently invoked to account for the Galactic foreground anomalous microwave emission. These grains, if present, will absorb starlight in the far ultraviolet (UV). There is also renewed interest in attributing the enigmatic 2175 Å interstellar extinction bump to small silicates. To probe the role of silicon in the UV extinction, we explore the relations between the amount of silicon required to be locked up in silicates [Si/H]dust and the 2175 Å bump or the far-UV extinction rise, based on an analysis of the extinction curves along 46 Galactic sightlines for which the gas-phase silicon abundance [Si/H]gas is known. We derive [Si/H]dust either from [Si/H]ISM - [Si/H]gas or from the Kramers- Kronig relation which relates the wavelength-integrated extinction to the total dust volume, where [Si/H]ISM is the interstellar silicon reference abundance and taken to be that of proto-Sun or B stars. We also derive [Si/H]dust from fi�tting the observed extinction curves with a mixture of amorphous silicates and graphitic grains. We fi�nd that in all three cases [Si/H]dust shows no correlation with the 2175 Å bump, while the carbon depletion [C/H]dust tends to correlate with the 2175 Å bump. This supports carbon grains instead of silicates as the possible carrier of the 2175 Å bump. We also �find that neither [Si/H]dust nor [C/H]dust alone correlates with the far-UV extinction, suggesting that the far-UV extinction is a combined effect of small carbon grains and silicates.

  11. Post-Retrieval Extinction Attenuates Cocaine Memories

    OpenAIRE

    Sartor, Gregory C; Aston-Jones, Gary

    2013-01-01

    Recent studies have shown that post-retrieval extinction training attenuates fear and reward-related memories in both humans and rodents. This noninvasive, behavioral approach has the potential to be used in clinical settings to treat maladaptive memories that underlie several psychiatric disorders, including drug addiction. However, few studies to date have used a post-retrieval extinction approach to attenuate addiction-related memories. In the current study, we attempted to disrupt cocaine...

  12. Modelling the extinction of Steller's sea cow

    OpenAIRE

    Turvey, S.T; Risley, C.L

    2005-01-01

    Steller's sea cow, a giant sirenian discovered in 1741 and extinct by 1768, is one of the few megafaunal mammal species to have died out during the historical period. The species is traditionally considered to have been exterminated by ‘blitzkrieg’-style direct overharvesting for food, but it has also been proposed that its extinction resulted from a sea urchin population explosion triggered by extirpation of local sea otter populations that eliminated the shallow-water kelps on which sea cow...

  13. A model for evolution and extinction

    OpenAIRE

    Roberts, Bruce W.; Newman, M. E. J.

    1995-01-01

    We present a model for evolution and extinction in large ecosystems. The model incorporates the effects of interactions between species and the influences of abiotic environmental factors. We study the properties of the model by approximate analytic solution and also by numerical simulation, and use it to make predictions about the distribution of extinctions and species lifetimes that we would expect to see in real ecosystems. It should be possible to test these predictions against the fossi...

  14. Extinction of laminar partially premixed flames

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, Suresh K. [Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor Street, Room 2039, MC-251, Chicago, IL 60607-7022 (United States)

    2009-12-15

    Flame extinction represents one of the classical phenomena in combustion science. It is important to a variety of combustion systems in transportation and power generation applications. Flame extinguishment studies are also motivated from the consideration of fire safety and suppression. Such studies have generally considered non-premixed and premixed flames, although fires can often originate in a partially premixed mode, i.e., fuel and oxidizer are partially premixed as they are transported to the reaction zone. Several recent investigations have considered this scenario and focused on the extinction of partially premixed flames (PPFs). Such flames have been described as hybrid flames possessing characteristics of both premixed and non-premixed flames. This paper provides a review of studies dealing with the extinction of PPFs, which represent a broad family of flames, including double, triple (tribrachial), and edge flames. Theoretical, numerical and experimental studies dealing with the extinction of such flames in coflow and counterflow configurations are discussed. Since these flames contain both premixed and non-premixed burning zones, a brief review of the dilution-induced extinction of premixed and non-premixed flames is also provided. For the coflow configuration, processes associated with flame liftoff and blowout are described. Since lifted non-premixed jet flames often contain a partially premixed or an edge-flame structure prior to blowout, the review also considers such flames. While the perspective of this review is broad focusing on the fundamental aspects of flame extinction and blowout, results mostly consider flame extinction caused by the addition of a flame suppressant, with relevance to fire suppression on earth and in space environment. With respect to the latter, the effect of gravity on the extinction of PPFs is discussed. Future research needs are identified. (author)

  15. The extinction of the West African lion: whose responsibility?

    NARCIS (Netherlands)

    Nollkaemper, A.

    2014-01-01

    A recently published study showed that the lion in West Africa is now critically endangered and faces extinction. From one angle, this would be just one of the large (though unknown) number of species that has previously faced extinction or has even become extinct. But the risk of extinction of some

  16. Compound Stimulus Extinction Reduces Spontaneous Recovery in Humans

    Science.gov (United States)

    Coelho, Cesar A. O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.

    2015-01-01

    Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design ("deepened extinction") shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately…

  17. AESoP: Astronomical Extinction Spectrophotometer

    Science.gov (United States)

    Linford, Justin; McGraw, J.; Zimmer, P.; Ackermann, M.; Fitch, J.

    2009-01-01

    The Earth's atmosphere is a major obstruction to the precision and accuracy of ground-based photometry. The atmosphere removes light from astronomical objects both by absorption and scattering by constituent molecules, aerosols and clouds. These effects can change significantly over short time periods and over modest angles on the sky. To further understand these effects, the UNM Measurement Astrophysics Group has designed, built and recently deployed the Astronomical Extinction Spectrophotometer (AESoP), a 100mm objective grating spectrometer. By monitoring bright stars in sensibly the same direction as a larger photometric telescope is observing, AESoP will measure the wavelength-dependent extinction due to the Earth's atmosphere from 450nm to 900nm on time scales of approximately one minute. The collocated Astronomical LIDAR for Extinction (ALE) provides a high-precision monochromatic extinction measurement at 527nm. Knowing the extinction at a single wavelength allows us to pin the relative spectra generated by AESoP. These extinction spectra can then be integrated over the bandpass of the photometric telescope system to create real time corrections of observations. We present the design and construction of AESoP along with the preliminary results of our first combined observing campaign. This effort is our first step toward breaking the 1% photometry barrier. This project is funded by AFRL Grant FA9451-04-2-0355

  18. How does climate change cause extinction?

    Science.gov (United States)

    Cahill, Abigail E; Aiello-Lammens, Matthew E; Fisher-Reid, M Caitlin; Hua, Xia; Karanewsky, Caitlin J; Ryu, Hae Yeong; Sbeglia, Gena C; Spagnolo, Fabrizio; Waldron, John B; Warsi, Omar; Wiens, John J

    2013-01-07

    Anthropogenic climate change is predicted to be a major cause of species extinctions in the next 100 years. But what will actually cause these extinctions? For example, will it be limited physiological tolerance to high temperatures, changing biotic interactions or other factors? Here, we systematically review the proximate causes of climate-change related extinctions and their empirical support. We find 136 case studies of climatic impacts that are potentially relevant to this topic. However, only seven identified proximate causes of demonstrated local extinctions due to anthropogenic climate change. Among these seven studies, the proximate causes vary widely. Surprisingly, none show a straightforward relationship between local extinction and limited tolerances to high temperature. Instead, many studies implicate species interactions as an important proximate cause, especially decreases in food availability. We find very similar patterns in studies showing decreases in abundance associated with climate change, and in those studies showing impacts of climatic oscillations. Collectively, these results highlight our disturbingly limited knowledge of this crucial issue but also support the idea that changing species interactions are an important cause of documented population declines and extinctions related to climate change. Finally, we briefly outline general research strategies for identifying these proximate causes in future studies.

  19. Extinction rates in North American freshwater fishes, 1900-2010

    Science.gov (United States)

    Burkhead, Noel M.

    2012-01-01

    Widespread evidence shows that the modern rates of extinction in many plants and animals exceed background rates in the fossil record. In the present article, I investigate this issue with regard to North American freshwater fishes. From 1898 to 2006, 57 taxa became extinct, and three distinct populations were extirpated from the continent. Since 1989, the numbers of extinct North American fishes have increased by 25%. From the end of the nineteenth century to the present, modern extinctions varied by decade but significantly increased after 1950 (post-1950s mean = 7.5 extinct taxa per decade). In the twentieth century, freshwater fishes had the highest extinction rate worldwide among vertebrates. The modern extinction rate for North American freshwater fishes is conservatively estimated to be 877 times greater than the background extinction rate for freshwater fishes (one extinction every 3 million years). Reasonable estimates project that future increases in extinctions will range from 53 to 86 species by 2050.

  20. Recent developments in the behavioural and pharmacological enhancement of extinction of drug seeking.

    Science.gov (United States)

    Chesworth, Rose; Corbit, Laura H

    2017-01-01

    One of the principal barriers to overcoming addiction is the propensity to relapse, even after months or years of abstinence. Relapse can be precipitated by cues and contexts associated with drug use; thus, decreasing the conditioned properties of these cues and contexts may assist in preventing relapse. The predictive power of drug cues and contexts can be reduced by repeatedly presenting them in the absence of the drug reinforcer, a process known as extinction. The potential of extinction to limit relapse has generated considerable interest and research over the past few decades. While pre-clinical animal models suggest extinction learning assists relapse prevention, treatment efficacy is often lacking when extinction learning principles are translated into clinical trials. Conklin and Tiffany (Addiction, 2002) suggest the lack of efficacy in clinical practice may be due to limited translation of procedures demonstrated through animal research and propose several methodological improvements to enhance extinction learning for drug addiction. This review will examine recent advances in the behavioural and pharmacological manipulation of extinction learning, based on research from pre-clinical models. In addition, the translation of pre-clinical findings-both those suggested by Conklin and Tiffany () and novel demonstrations from the past 13 years-into clinical trials and the efficacy of these methods in reducing craving and relapse, where available, will be discussed. Finally, we highlight areas where promising pre-clinical models have not yet been integrated into current clinical practice but, if applied, could improve upon existing behavioural and pharmacological methods. © 2015 Society for the Study of Addiction.

  1. The Late Ordovician Extinction: How it became the best understood of the five major extinctions.

    Science.gov (United States)

    Sheehan, P.

    2003-04-01

    The end Ordovician extinction has become arguably the best-understood major extinction event in Earth History. A plethora of workers have established the pattern of faunal change and causes of the extinction with remarkably little disagreement. The first indication of increased extinction at the end of the Ordovician was a graph of global diversity patterns by Norman Newell in 1967, although he did not recognize it as a major event. The presence of a major extinction event became clear as William Berry and Art Boucot assembled data for Silurian correlation charts in the late 1960s. The first reports of North African glaciation in the late 1960s provided a cause for the extinction and study of the event snowballed. It was no accident that recognition of the extinction began in North America, because it was there that the extinction completely overturned faunas in the epicontinental seas. Glacio-eustatic regression of shallow seaway coincided with the disappearance of endemic Laurentian faunas and replacement by a highly cosmopolitan fauna in the Silurian. Once the event was established in North America, paleontologists soon found evidence of the event around the globe. The well-documented Hirnantia Fauna was found to correspond to the glacial interval, and Pat Brenchley soon recognized that there were two pulses of extinction, at the beginning and end of the glaciation. At the same time that the faunal changes were being documented geologic studies of the glaciation provided information on the environmental changes associated with the extinction. The timing of the glacial maximum was established in Africa and by the presence of dropstones in high latitude marine rocks. The 1990s saw geochemical techniques employed that allowed examination of atmospheric CO2 and temperature changes. In many places carbonate deposition declined. Glacio-eustatic regression was obvious in many areas, and a sea-level decline in the range of 50-100 m was established. Shallow

  2. The Topological Properties of Stimuli Influence Fear Generalization and Extinction in Humans.

    Science.gov (United States)

    Xu, Liang; Su, Hongyu; Xie, Xiaoyuan; Yan, Pei; Li, Junjiao; Zheng, Xifu

    2018-01-01

    Fear generalization is an etiologically significant indicator of anxiety disorders, and understanding how to inhibit it is important in their treatment. Prior studies have found that reducing fear generalization using a generalization stimulus (GS) is ineffective in removing a conditioned fear that incorporates local features, and that topological properties appear to play a comparatively more significant role in the processes of perception and categorization. Our study utilized a conditioned-fear generalization design to examine whether the topological properties of stimuli influence the generalization and return of fear. Fear was indexed using online expectancy ratings and skin conductance responses (SCRs). The study's 52 participants were divided into three groups: Group 1, conditioned danger cue (CS+) extinction; Group 2, extinction of one GS; Group 3, extinction of three GSs. We found that the three groups acquired conditioned fear at the same level. In the generalization and extinction phase, fear was transferred to the GS with the same topological properties as CS+, and gradual decreases in both shock expectancy and SCRs over non-reinforced extinction trials were observed. In the test phase, participants' online expectancy ratings indicated that fear did not return in Group 1, but did return in Groups 2 and 3. All three groups demonstrated successful GS fear extinction, but only Group 1 did not show a return of fear for CS+. Regarding SCRs results, none of the groups demonstrated a return of fear, suggesting that utilization of topological properties successfully reduced the return of conditioned fear. Our results indicate that, in clinical settings, using GS with topological equivalence to CS+ might offer a potential method with which to extinct conditioned fear.

  3. The Topological Properties of Stimuli Influence Fear Generalization and Extinction in Humans

    Directory of Open Access Journals (Sweden)

    Liang Xu

    2018-03-01

    Full Text Available Fear generalization is an etiologically significant indicator of anxiety disorders, and understanding how to inhibit it is important in their treatment. Prior studies have found that reducing fear generalization using a generalization stimulus (GS is ineffective in removing a conditioned fear that incorporates local features, and that topological properties appear to play a comparatively more significant role in the processes of perception and categorization. Our study utilized a conditioned-fear generalization design to examine whether the topological properties of stimuli influence the generalization and return of fear. Fear was indexed using online expectancy ratings and skin conductance responses (SCRs. The study’s 52 participants were divided into three groups: Group 1, conditioned danger cue (CS+ extinction; Group 2, extinction of one GS; Group 3, extinction of three GSs. We found that the three groups acquired conditioned fear at the same level. In the generalization and extinction phase, fear was transferred to the GS with the same topological properties as CS+, and gradual decreases in both shock expectancy and SCRs over non-reinforced extinction trials were observed. In the test phase, participants’ online expectancy ratings indicated that fear did not return in Group 1, but did return in Groups 2 and 3. All three groups demonstrated successful GS fear extinction, but only Group 1 did not show a return of fear for CS+. Regarding SCRs results, none of the groups demonstrated a return of fear, suggesting that utilization of topological properties successfully reduced the return of conditioned fear. Our results indicate that, in clinical settings, using GS with topological equivalence to CS+ might offer a potential method with which to extinct conditioned fear.

  4. Immediate Extinction Causes a Less Durable Loss of Performance than Delayed Extinction following Either Fear or Appetitive Conditioning

    Science.gov (United States)

    Woods, Amanda M.; Bouton, Mark E.

    2008-01-01

    Five experiments with rat subjects compared the effects of immediate and delayed extinction on the durability of extinction learning. Three experiments examined extinction of fear conditioning (using the conditioned emotional response method), and two experiments examined extinction of appetitive conditioning (using the food-cup entry method). In…

  5. Bilateral Alternating Auditory Stimulations Facilitate Fear Extinction and Retrieval

    OpenAIRE

    Boukezzi, Sarah; Silva, Catarina; Nazarian, Bruno; Rousseau, Pierre-François; Guedj, Eric; Valenzuela-Moguillansky, Camila; Khalfa, Stéphanie

    2017-01-01

    Disruption of fear conditioning, its extinction and its retrieval are at the core of posttraumatic stress disorder (PTSD). Such deficits, especially fear extinction delay, disappear after alternating bilateral stimulations (BLS) during eye movement desensitization and reprocessing (EMDR) therapy. An animal model of fear recovery, based on auditory cued fear conditioning and extinction learning, recently showed that BLS facilitate fear extinction and fear extinction retrieval. Our goal was to ...

  6. Alleviating soil acidity through plant organic compounds

    Directory of Open Access Journals (Sweden)

    Anderson R. Meda

    2001-06-01

    Full Text Available A laboratory experiment was conducted to evaluate the effects of water soluble plant extracts on soil acidity. The plant materials were: black oat, oil seed radish, white and blue lupin, gray and dwarf mucuna, Crotalaria spectabilis and C. breviflora, millet, pigeon pea, star grass, mato grosso grass, coffee leaves, sugar cane leaves, rice straw, and wheat straw. Plant extracts were added on soil surface in a PVC soil column at a rate of 1.0 ml min-1. Both soil and drainage water were analyzed for pH, Ca, Al, and K. Plant extracts applied on the soil surface increased soil pH, exchangeable Ca ex and Kex and decreased Al ex. Oil seed radish, black oat, and blue lupin were the best and millet the worst materials to alleviate soil acidity. Oil seed radish markedly increased Al in the drainage water. Chemical changes were associated with the concentrations of basic cations in the plant extract: the higher the concentration the greater the effects in alleviating soil acidity.Foram conduzidos experimentos de laboratórios para avaliar os efeitos de extratos de plantas solúveis em água na acidez do solo. Os materiais de plantas foram: aveia preta, nabo, tremoço branco e azul, mucuna cinza e anã, Crotalaria spectabilis e C. breviflora, milheto, guandu, grama estrela, grama mato grosso, folhas de café, folhas de cana-de-açúcar, palhada de arroz e palhada de trigo. Foi utilizado o seguinte procedimento para o extrato da planta solúvel em água: pesar 3g de material de planta, adicionar 150 ml de água, agitar por 8h e filtrar. Os extratos de plantas foram adicionados na superfície do solo em uma coluna de PVC (1 ml min-1. Após, adicionou-se água deionizada em quantidade equivalente a três volumes de poros. Os extratos de plantas aumentaram o pH, Ca e K trocável e diminuíram Al. Nabo, aveia preta e tremoço azul foram os melhores e milheto o pior material para amenizar a acidez do solo. Nabo aumentou Al na água de drenagem. As altera

  7. Impact of government poverty alleviation programmes on the socio ...

    African Journals Online (AJOL)

    Despite these programmes, poverty still exists among Nigerians especially the youth. This study therefore examines the impact of government poverty alleviation programmes on the youth. The population of the study comprised of all youths who have benefited from government poverty alleviation programmes. The Random ...

  8. Sensor comparison study for load alleviating wind turbine pitch control

    DEFF Research Database (Denmark)

    Kragh, Knud Abildgaard; Hansen, Morten Hartvig; Henriksen, Lars Christian

    2014-01-01

    As the size of wind turbines increases, the load alleviating capabilities of the turbine controller are becoming increasingly important. Load alleviating control schemes have traditionally been based on feedback from load sensor; however, recent developments of measurement technologies have enabled...... control on the basis of preview measurements of the inflow acquired using, e.g., light detection and ranging. The potential of alleviating load variations that are caused by mean wind speed changes through feed-forward control have been demonstrated through both experiments and simulations in several...... studies, whereas the potential of preview control for alleviating the load variations caused by azimuth dependent inflow variations is less described. Individual or cyclic pitch is required to alleviate azimuth dependent load variations and is traditionally applied through feedback control of the blade...

  9. Extinction Generates Outcome-Specific Conditioned Inhibition.

    Science.gov (United States)

    Laurent, Vincent; Chieng, Billy; Balleine, Bernard W

    2016-12-05

    Extinction involves altering a previously established predictive relationship between a cue and its outcome by repeatedly presenting that cue alone. Although it is widely accepted that extinction generates some form of inhibitory learning [1-4], direct evidence for this claim has been lacking, and the nature of the associative changes induced by extinction have, therefore, remained a matter of debate [5-8]. In the current experiments, we used a novel behavioral approach that we recently developed and that provides a direct measure of conditioned inhibition [9] to compare the influence of extinguished and non-extinguished cues on choice between goal-directed actions. Using this approach, we provide direct evidence that extinction generates outcome-specific conditioned inhibition. Furthermore, we demonstrate that this inhibitory learning is controlled by the infralimbic cortex (IL); inactivation of the IL using M4 DREADDs abolished outcome-specific inhibition and rendered the cue excitatory. Importantly, we found that context modulated this inhibition. Outside its extinction context, the cue was excitatory and functioned as a specific predictor of its previously associated outcome, biasing choice toward actions earning the same outcome. In its extinction context, however, the cue acted as a specific inhibitor and biased choice toward actions earning different outcomes. Context modulation of these excitatory and inhibitory memories was mediated by the dorsal hippocampus (HPC), suggesting that the HPC and IL act in concert to control the influence of conditioned inhibitors on choice. These findings demonstrate for the first time that extinction turns a cue into a net inhibitor that can influence choice via counterfactual action-outcome associations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Elevational distribution and extinction risk in birds.

    Directory of Open Access Journals (Sweden)

    Rachel L White

    Full Text Available Mountainous regions are hotspots of terrestrial biodiversity. Unlike islands, which have been the focus of extensive research on extinction dynamics, fewer studies have examined mountain ranges even though they face increasing threats from human pressures - notably habitat conversion and climate change. Limits to the taxonomic and geographical extent and resolution of previously available information have precluded an explicit assessment of the relative role of elevational distribution in determining extinction risk. We use a new global species-level avian database to quantify the influence of elevational distribution (range, maximum and midpoint on extinction risk in birds at the global scale. We also tested this relationship within biogeographic realms, higher taxonomic levels, and across phylogenetic contrasts. Potential confounding variables (i.e. phylogenetic, distributional, morphological, life history and niche breadth were also tested and controlled for. We show that the three measures of elevational distribution are strong negative predictors of avian extinction risk, with elevational range comparable and complementary to that of geographical range size. Extinction risk was also found to be positively associated with body weight, development and adult survival, but negatively associated with reproduction and niche breadth. The robust and consistent findings from this study demonstrate the importance of elevational distribution as a key driver of variation in extinction dynamics in birds. Our results also highlight elevational distribution as a missing criterion in current schemes for quantifying extinction risk and setting species conservation priorities in birds. Further research is recommended to test for generality across non-avian taxa, which will require an advance in our knowledge of species' current elevational ranges and increased efforts to digitise and centralise such data.

  11. Alleviating energy poverty for the world's poor

    International Nuclear Information System (INIS)

    Sagar, Ambuj D.

    2005-01-01

    Improving energy services for poor households in developing countries remains one of the most pressing challenges facing the development community. The dependence of these households on traditional forms of energy leads to significant health impacts as well as other major disbenefits, yet there has been little progress in meeting this challenge. This viewpoint argues for an 'energy-poverty alleviation' fund to help provide modern energy services to these households. It also proposes an approach through which to create such a fund, namely by introducing an incremental levy on petroleum. Notably, this scheme does not need a global agreement since a levy could be introduced by major oil-exporting countries. The implementation of this mechanism would result in a climate-friendly outcome (even before taking into account the elimination of products of incomplete combustion resulting from the traditional household use of biomass-based fuels) while providing immense socio-economic benefits to the world's poor. Such an approach would allow significant progress on the sustainable development front while reducing global greenhouse gas emissions, and therefore is very much consistent with the United Nations Framework Convention on Climate Change

  12. Lactobacillus plantarum CCFM639 alleviates aluminium toxicity.

    Science.gov (United States)

    Yu, Leilei; Zhai, Qixiao; Liu, Xiaoming; Wang, Gang; Zhang, Qiuxiang; Zhao, Jianxin; Narbad, Arjan; Zhang, Hao; Tian, Fengwei; Chen, Wei

    2016-02-01

    Aluminium (Al) is the most abundant metal in the earth's crust. Al exposure can cause a variety of adverse physiological effects in humans and animals. Our aim was to demonstrate that specific probiotic bacteria can play a special physiologically functional role in protection against Al toxicity in mice. Thirty strains of lactic acid bacteria (LAB) were tested for their aluminium-binding ability, aluminium tolerance, their antioxidative capacity, and their ability to survive the exposure to artificial gastrointestinal (GI) juices. Lactobacillus plantarum CCFM639 was selected for animal experiments because of its excellent performance in vitro. Forty mice were divided into four groups: control, Al only, Al plus CCFM639, and Al plus deferiprone (DFP). CCFM639 was administered at 10(9) CFU once daily for 10 days, followed by a single oral dose of aluminium chloride hexahydrate at 5.14 mg aluminium (LD50) for each mouse. The results showed that CCFM639 treatment led to a significant reduction in the mortality rates with corresponding decrease in intestinal aluminium absorption and in accumulation of aluminium in the tissues and amelioration of hepatic histopathological damage. This probiotic treatment also resulted in alleviation of hepatic, renal, and cerebral oxidative stress. The treatment of L. plantarum CCFM639 has potential as a therapeutic dietary strategy against acute aluminium toxicity.

  13. Extinctions. Paleontological baselines for evaluating extinction risk in the modern oceans.

    Science.gov (United States)

    Finnegan, Seth; Anderson, Sean C; Harnik, Paul G; Simpson, Carl; Tittensor, Derek P; Byrnes, Jarrett E; Finkel, Zoe V; Lindberg, David R; Liow, Lee Hsiang; Lockwood, Rowan; Lotze, Heike K; McClain, Craig R; McGuire, Jenny L; O'Dea, Aaron; Pandolfi, John M

    2015-05-01

    Marine taxa are threatened by anthropogenic impacts, but knowledge of their extinction vulnerabilities is limited. The fossil record provides rich information on past extinctions that can help predict biotic responses. We show that over 23 million years, taxonomic membership and geographic range size consistently explain a large proportion of extinction risk variation in six major taxonomic groups. We assess intrinsic risk-extinction risk predicted by paleontologically calibrated models-for modern genera in these groups. Mapping the geographic distribution of these genera identifies coastal biogeographic provinces where fauna with high intrinsic risk are strongly affected by human activity or climate change. Such regions are disproportionately in the tropics, raising the possibility that these ecosystems may be particularly vulnerable to future extinctions. Intrinsic risk provides a prehuman baseline for considering current threats to marine biodiversity. Copyright © 2015, American Association for the Advancement of Science.

  14. Facilitation of extinction and re-extinction of operant behavior in mice by chlordiazepoxide and D-cycloserine.

    Science.gov (United States)

    Leslie, Julian C; Norwood, Kelly

    2013-05-01

    The aim was to compare operant extinction with re-extinction following re-acquisition and to investigate neuropharmacological mechanisms through administration of drugs potentiating GABAergic or glutamatergic systems. Groups of C57Bl/6 mice were trained to lever press for food on a fixed ratio schedule, then extinguished with or without pre-session chlordiazepoxide or post-session d-cycloserine administration (15mg/kg in each case), then retrained to lever press for food, then re-extinguished with or without pre-session chlordiazepoxide or post-session d-cycloserine. Under vehicle injections, extinction and re-extinction curves were indistinguishable, but drug treatments showed that there was less resistance to extinction in the re-extinction phase. Chlordiazepoxide facilitated extinction and re-extinction, with an earlier effect during re-extinction. d-Cycloserine also facilitated extinction and re-extinction, with some evidence of an earlier effect during re-extinction. These results replicate and extend earlier findings with operant extinction, but differ from some previous reports of d-cycloserine on re-extinction of Pavlovian conditioned fear. Implications for accounts of the similarities and differences between neural mechanisms of extinction following either Pavlovian or operant conditioning, and applications of these findings, are discussed. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. A preregistered, direct replication attempt of the retrieval-extinction effect in cued fear conditioning in rats.

    Science.gov (United States)

    Luyten, Laura; Beckers, Tom

    2017-10-01

    In 2009, Monfils and colleagues proposed a behavioral procedure that was said to result in a permanent attenuation of a previously established fear memory, thereby precluding a possible return of fear after extinction (Monfils, Cowansage, Klann, & LeDoux, 2009). By presenting a single retrieval trial one hour before standard extinction training, they found an enduring reduction of fear. The retrieval-extinction procedure holds great clinical potential, particularly for anxiety patients, but the findings are not undisputed, and several conceptual replications have failed to reproduce the effect. These failures have largely been attributed to small procedural differences. This preregistered study is the first endeavor to exactly replicate three key experiments of the original report by Monfils et al. (2009), thereby gauging the robustness of their seminal findings. Despite adhering to the original procedures as closely as possible, we did not find any evidence for reduced return of fear with the retrieval-extinction procedure relative to regular extinction training, as assessed through spontaneous recovery, reinstatement and renewal. Behavior of animals in the control condition (extinction only) was comparable to that in the original studies and provided an adequate baseline to reveal differences with the retrieval-extinction condition. Our null findings indicate that the effect sizes in the original paper may have been inflated and question the legitimacy of previously proposed moderators of the retrieval-extinction effect. We argue that direct experimental evaluation of purported moderators of the retrieval-extinction effect will be key to shed more light on its nature and prerequisites. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Fluoxetine Facilitates Fear Extinction Through Amygdala Endocannabinoids

    Science.gov (United States)

    Gunduz-Cinar, Ozge; Flynn, Shaun; Brockway, Emma; Kaugars, Katherine; Baldi, Rita; Ramikie, Teniel S; Cinar, Resat; Kunos, George; Patel, Sachin; Holmes, Andrew

    2016-01-01

    Pharmacologically elevating brain endocannabinoids (eCBs) share anxiolytic and fear extinction-facilitating properties with classical therapeutics, including the selective serotonin reuptake inhibitor, fluoxetine. There are also known functional interactions between the eCB and serotonin systems and preliminary evidence that antidepressants cause alterations in brain eCBs. However, the potential role of eCBs in mediating the facilitatory effects of fluoxetine on fear extinction has not been established. Here, to test for a possible mechanistic contribution of eCBs to fluoxetine's proextinction effects, we integrated biochemical, electrophysiological, pharmacological, and behavioral techniques, using the extinction-impaired 129S1/Sv1mJ mouse strain. Chronic fluoxetine treatment produced a significant and selective increase in levels of anandamide in the BLA, and an associated decrease in activity of the anandamide-catabolizing enzyme, fatty acid amide hydrolase. Slice electrophysiological recordings showed that fluoxetine-induced increases in anandamide were associated with the amplification of eCB-mediated tonic constraint of inhibitory, but not excitatory, transmission in the BLA. Behaviorally, chronic fluoxetine facilitated extinction retrieval in a manner that was prevented by systemic or BLA-specific blockade of CB1 receptors. In contrast to fluoxetine, citalopram treatment did not increase BLA eCBs or facilitate extinction. Taken together, these findings reveal a novel, obligatory role for amygdala eCBs in the proextinction effects of a major pharmacotherapy for trauma- and stressor-related disorders and anxiety disorders. PMID:26514583

  17. Neural signals of vicarious extinction learning.

    Science.gov (United States)

    Golkar, Armita; Haaker, Jan; Selbing, Ida; Olsson, Andreas

    2016-10-01

    Social transmission of both threat and safety is ubiquitous, but little is known about the neural circuitry underlying vicarious safety learning. This is surprising given that these processes are critical to flexibly adapt to a changeable environment. To address how the expression of previously learned fears can be modified by the transmission of social information, two conditioned stimuli (CS + s) were paired with shock and the third was not. During extinction, we held constant the amount of direct, non-reinforced, exposure to the CSs (i.e. direct extinction), and critically varied whether another individual-acting as a demonstrator-experienced safety (CS + vic safety) or aversive reinforcement (CS + vic reinf). During extinction, ventromedial prefrontal cortex (vmPFC) responses to the CS + vic reinf increased but decreased to the CS + vic safety This pattern of vmPFC activity was reversed during a subsequent fear reinstatement test, suggesting a temporal shift in the involvement of the vmPFC. Moreover, only the CS + vic reinf association recovered. Our data suggest that vicarious extinction prevents the return of conditioned fear responses, and that this efficacy is reflected by diminished vmPFC involvement during extinction learning. The present findings may have important implications for understanding how social information influences the persistence of fear memories in individuals suffering from emotional disorders. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  18. Selection, subdivision and extinction and recolonization.

    Science.gov (United States)

    Cherry, Joshua L

    2004-02-01

    In a subdivided population, the interaction between natural selection and stochastic change in allele frequency is affected by the occurrence of local extinction and subsequent recolonization. The relative importance of selection can be diminished by this additional source of stochastic change in allele frequency. Results are presented for subdivided populations with extinction and recolonization where there is more than one founding allele after extinction, where these may tend to come from the same source deme, where the number of founding alleles is variable or the founders make unequal contributions, and where there is dominance for fitness or local frequency dependence. The behavior of a selected allele in a subdivided population is in all these situations approximately the same as that of an allele with different selection parameters in an unstructured population with a different size. The magnitude of the quantity N(e)s(e), which determines fixation probability in the case of genic selection, is always decreased by extinction and recolonization, so that deleterious alleles are more likely to fix and advantageous alleles less likely to do so. The importance of dominance or frequency dependence is also altered by extinction and recolonization. Computer simulations confirm that the theoretical predictions of both fixation probabilities and mean times to fixation are good approximations.

  19. Mass Extinctions and Biosphere-Geosphere Stability

    Science.gov (United States)

    Rothman, Daniel; Bowring, Samuel

    2015-04-01

    Five times in the past 500 million years, mass extinctions have resulted in the loss of greater than three-fourths of living species. Each of these events is associated with significant environmental change recorded in the carbon-isotopic composition of sedimentary rocks. There are also many such environmental events in the geologic record that are not associated with mass extinctions. What makes them different? Two factors appear important: the size of the environmental perturbation, and the time scale over which it occurs. We show that the natural perturbations of Earth's carbon cycle during the past 500 million years exhibit a characteristic rate of change over two orders of magnitude in time scale. This characteristic rate is consistent with the maximum rate that limits quasistatic (i.e., near steady-state) evolution of the carbon cycle. We identify this rate with marginal stability, and show that mass extinctions occur on the fast, unstable side of the stability boundary. These results suggest that the great extinction events of the geologic past, and potentially a "sixth extinction" associated with modern environmental change, are characterized by common mechanisms of instability.

  20. Quantitative analysis of forest fire extinction efficiency

    Directory of Open Access Journals (Sweden)

    Miguel E. Castillo-Soto

    2015-08-01

    Full Text Available Aim of study: Evaluate the economic extinction efficiency of forest fires, based on the study of fire combat undertaken by aerial and terrestrial means. Area of study, materials and methods: Approximately 112,000 hectares in Chile. Records of 5,876 forest fires that occurred between 1998 and 2009 were analyzed. The area further provides a validation sector for results, by incorporating databases for the years 2010 and 2012. The criteria used for measuring extinction efficiency were economic value of forestry resources, Contraction Factor analysis and definition of the extinction costs function. Main results: It is possible to establish a relationship between burnt area, extinction costs and economic losses. The method proposed may be used and adapted to other fire situations, requiring unit costs for aerial and terrestrial operations, economic value of the property to be protected and speed attributes of fire spread in free advance. Research highlights: The determination of extinction efficiency in containment works of forest fires and potential projection of losses, different types of plant fuel and local conditions favoring the spread of fire broaden the admissible ranges of a, φ and Ce considerably.

  1. Yohimbine Enhancement of Exposure Therapy for Social Anxiety Disorder: A Randomized Controlled Trial

    NARCIS (Netherlands)

    Smits, J.A.J.; Rosenfield, D.; Davis, M.L.; Julian, K.; Handelsman, P.R.; Otto, M.W.; Tuerk, P.; Shiekh, M.; Rosenfield, B.; Hofmann, S.G.; Powers, M.B.

    2014-01-01

    Background Preclinical and clinical trials suggest that yohimbine may augment extinction learning without significant side effects. However, previous clinical trials have only examined adults with specific phobias. Yohimbine has not yet been investigated in the augmentation of exposure therapy for

  2. Policy Review on Watershed Protection and Poverty Alleviation by the Grain for Green Program in China

    Institute of Scientific and Technical Information of China (English)

    LIZhiyong

    2004-01-01

    The sustained growth of Chinese economy in the new century is a silver lining in the continuously depressed global economy. Meanwhile, the rapid development of Chinese economy is still confronted with constraints from deteriorating environment and rural poverty issues. It has become a significant policy option in maintaining high speed, efficiency and sound development of Chinese economy to rehabilitate forest resources, improve ecological conditions, increase farmers' income and get on a sustainable road featuring coordinated development of population, resources and environment. The Grain for Green Program, as a CDM activity of Chinese style, launched on trial in 1999 and implemented in 2002 across the country, is the biggest land use transition, watershed management and poverty alleviation program involving the largest population in Chinese history and across the globe. It covers 25 provinces/regions/cities and gets over 1600 counties, 15 million households and 60 million farmers were involved. Hence the Grain for Tree policy has a significant bearing on ecological protection and farmers' poverty alleviation in the soil and water erosion-prone region. A review and assessment of the background, essentials, effects, problems and trend of the Grain for Tree policy is of great significance for both China and the other developing countries in the world in their efforts to combat the deteriorating environment and alleviate poverty.

  3. Why may allopregnanolone help alleviate loneliness?

    Science.gov (United States)

    Cacioppo, S; Cacioppo, J T

    2015-12-01

    Impaired biosynthesis of Allopregnanolone (ALLO), a brain endogenous neurosteroid, has been associated with numerous behavioral dysfunctions, which range from anxiety- and depressive-like behaviors to aggressive behavior and changes in responses to contextual fear conditioning in rodent models of emotional dysfunction. Recent animal research also demonstrates a critical role of ALLO in social isolation. Although there are likely aspects of perceived social isolation that are uniquely human, there is also continuity across species. Both human and animal research show that perceived social isolation (which can be defined behaviorally in animals and humans) has detrimental effects on physical health, such as increased hypothalamic pituitary adrenal (HPA) activity, decreased brain-derived neurotrophic factor (BDNF) expression, and increased depressive behavior. The similarities between animal and human research suggest that perceived social isolation (loneliness) may also be associated with a reduction in the synthesis of ALLO, potentially by reducing BDNF regulation and increasing HPA activity through the hippocampus, amygdala, and bed nucleus of the stria terminalis (BNST), especially during social threat processing. Accordingly, exogenous administration of ALLO (or ALLO precursor, such as pregnenolone), in humans may help alleviate loneliness. Congruent with our hypothesis, exogenous administration of ALLO (or ALLO precursors) in humans has been shown to improve various stress-related disorders that show similarities between animals and humans i.e., post-traumatic stress disorders, traumatic brain injuries. Because a growing body of evidence demonstrates the benefits of ALLO in socially isolated animals, we believe our ALLO hypothesis can be applied to loneliness in humans, as well. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Arctigenin alleviates ER stress via activating AMPK

    Science.gov (United States)

    Gu, Yuan; Sun, Xiao-xiao; Ye, Ji-ming; He, Li; Yan, Shou-sheng; Zhang, Hao-hao; Hu, Li-hong; Yuan, Jun-ying; Yu, Qiang

    2012-01-01

    Aim: To investigate the protective effects of arctigenin (ATG), a phenylpropanoid dibenzylbutyrolactone lignan from Arctium lappa L (Compositae), against ER stress in vitro and the underlying mechanisms. Methods: A cell-based screening assay for ER stress regulators was established. Cell viability was measured using MTT assay. PCR and Western blotting were used to analyze gene and protein expression. Silencing of the CaMKKβ, LKB1, and AMPKα1 genes was achieved by RNA interference (RNAi). An ATP bioluminescent assay kit was employed to measure the intracellular ATP levels. Results: ATG (2.5, 5 and 10 μmol/L) inhibited cell death and unfolded protein response (UPR) in a concentration-dependent manner in cells treated with the ER stress inducer brefeldin A (100 nmol/L). ATG (1, 5 and 10 μmol/L) significantly attenuated protein synthesis in cells through inhibiting mTOR-p70S6K signaling and eEF2 activity, which were partially reversed by silencing AMPKα1 with RNAi. ATG (1-50 μmol/L) reduced intracellular ATP level and activated AMPK through inhibiting complex I-mediated respiration. Pretreatment of cells with the AMPK inhibitor compound C (25 μmol/L) rescued the inhibitory effects of ATG on ER stress. Furthermore, ATG (2.5 and 5 μmol/L) efficiently activated AMPK and reduced the ER stress and cell death induced by palmitate (2 mmol/L) in INS-1 β cells. Conclusion: ATG is an effective ER stress alleviator, which protects cells against ER stress through activating AMPK, thus attenuating protein translation and reducing ER load. PMID:22705729

  5. Study of plutonium fire extinction in glove-boxes

    International Nuclear Information System (INIS)

    Boisson, H.; Chappellier, A.; Debiar, A.; Savornin, J.

    1965-01-01

    The report concerns attempts to extinguish fire in uranium - chosen as a basis for comparison - and in plutonium, these being contained in glove boxes. The extinguishing powders TEC and MG 10 were tried and compared. The operator used in plastic bags. The metal was dealt with respectively in the form of billets, compact chips and finally thin shavings. In each case fire control was without difficulty. One must allow a certain time for cooling. The powder MG 10 showed very good results. Moreover, the trials proved that densely packed shavings are a very real security factor. The interior lay-out of the glove boxes ought, in order to facilitate further manipulations, be such as to render extinction as easy as possible should the need arise. (authors) [fr

  6. Extinction times of epidemic outbreaks in networks.

    Science.gov (United States)

    Holme, Petter

    2013-01-01

    In the Susceptible-Infectious-Recovered (SIR) model of disease spreading, the time to extinction of the epidemics happens at an intermediate value of the per-contact transmission probability. Too contagious infections burn out fast in the population. Infections that are not contagious enough die out before they spread to a large fraction of people. We characterize how the maximal extinction time in SIR simulations on networks depend on the network structure. For example we find that the average distances in isolated components, weighted by the component size, is a good predictor of the maximal time to extinction. Furthermore, the transmission probability giving the longest outbreaks is larger than, but otherwise seemingly independent of, the epidemic threshold.

  7. Astrophysical life extinctions what killed the dinosaurs?

    CERN Document Server

    Dar, Arnon

    1999-01-01

    Geological records indicate that the exponential diversification of marine and continental life on Earth in the past 500 My was interrupted by many life extinctions. They also indicate that the major mass extinctions were correlated in time with large meteoritic impacts, gigantic volcanic eruptions, sea regressions and drastic changes in global climate. Some of these catastrophes coincided in time. The astrophysical life extinction mechanisms which were proposed so far, in particular, meteoritic impacts, nearby supernova explosions, passage through molecular or dark matter clouds, and Galactic gamma/cosmic ray bursts cannot explain the time coincidences between these catastrophes. However, recent observations suggest that many planetary-mass objects may be present in the outer solar system between the Kuiper belt and the Oort cloud. Gravitational perturbations may occasionally bring them into the inner solar system. Their passage near Earth could have generated gigantic tidal waves, large volcanic eruptions, ...

  8. Biotic extinctions by solar flares; and reply

    International Nuclear Information System (INIS)

    Beland, P.; Russell, D.A.; Crutzen, P.J.; Reid, G.C.

    1976-01-01

    Some comments are offered on the paper by Reid and others (nature 259:177 (1976)) in which a mechanism was suggested by which solar protons might catastrophically deplete atmospheric D 3 during a reversal of the Earth's geomagnetic field. Organisms would thereby be exposed to a more intense UV environment, leading to species extinctions. These authors assumed that during a reversal the geomagnetic field effectively disappears for about 1000 years, and also that solar flares sufficiently intense to cause extinctions occur at intervals of 1000 years or more. The validity of these assumptions is here examined using data on geomagnetic reversals identified over the past 75 M years, together with extinction data, and some anomalies are pointed out. A reply by Reid and others is appended. (U.K.)

  9. The fossil record of the sixth extinction.

    Science.gov (United States)

    Plotnick, Roy E; Smith, Felisa A; Lyons, S Kathleen

    2016-05-01

    Comparing the magnitude of the current biodiversity crisis with those in the fossil record is difficult without an understanding of differential preservation. Integrating data from palaeontological databases with information on IUCN status, ecology and life history characteristics of contemporary mammals, we demonstrate that only a small and biased fraction of threatened species (fossil record, compared with 20% of non-threatened species. We find strong taphonomic biases related to body size and geographic range. Modern species with a fossil record tend to be large and widespread and were described in the 19(th) century. The expected magnitude of the current extinction based only on species with a fossil record is about half of that of one based on all modern species; values for genera are similar. The record of ancient extinctions may be similarly biased, with many species having originated and gone extinct without leaving a tangible record. © 2016 John Wiley & Sons Ltd/CNRS.

  10. Extinction times of epidemic outbreaks in networks.

    Directory of Open Access Journals (Sweden)

    Petter Holme

    Full Text Available In the Susceptible-Infectious-Recovered (SIR model of disease spreading, the time to extinction of the epidemics happens at an intermediate value of the per-contact transmission probability. Too contagious infections burn out fast in the population. Infections that are not contagious enough die out before they spread to a large fraction of people. We characterize how the maximal extinction time in SIR simulations on networks depend on the network structure. For example we find that the average distances in isolated components, weighted by the component size, is a good predictor of the maximal time to extinction. Furthermore, the transmission probability giving the longest outbreaks is larger than, but otherwise seemingly independent of, the epidemic threshold.

  11. Mammal extinctions, body size, and paleotemperature.

    Science.gov (United States)

    Bown, T M; Holroyd, P A; Rose, K D

    1994-10-25

    There is a general inverse relationship between the natural logarithm of tooth area (a body size indicator) of some fossil mammals and paleotemperature during approximately 2.9 million years of the early Eocene in the Bighorn Basin of northwest Wyoming. When mean temperatures became warmer, tooth areas tended to become smaller. During colder times, larger species predominated; these generally became larger or remained the same size. Paleotemperature trends also markedly affected patterns of local (and, perhaps, regional) extinction and immigration. New species appeared as immigrants during or near the hottest (smaller forms) and coldest (larger forms) intervals. Paleotemperature trend reversals commonly resulted in the ultimate extinction of both small forms (during cooling intervals) and larger forms (during warming intervals). These immigrations and extinctions mark faunal turnovers that were also modulated by sharp increases in sediment accumulation rate.

  12. Pycnogenol may alleviate adverse effects in oncologic treatment.

    Science.gov (United States)

    Belcaro, G; Cesarone, M R; Genovesi, D; Ledda, A; Vinciguerra, G; Ricci, A; Pellegrini, L; Gizzi, G; Ippolito, E; Dugall, M; Cacchio, M; Di Renzo, A; Stuard, S

    2008-09-01

    A large variety of adverse reactions are well known to frequently occur during chemotherapy and radiotherapy in oncology. Specific medications exist to target individual side effects. The aim of this study was to explore in a pilot trial whether supplementation with French maritime pine bark extract Pycnogenol could alleviate side effects and improve patient's quality of life. Cancer patients who previously underwent surgery and who were in view of their pathology in relatively good condition, both physically and psychologically, were recruited for this study and divided into two groups. These patients received their first cycle of radiotherapy or chemotherapy, which lasted from 10 days up to 1 month. Then one group of patients received 150 mg Pycnogenol, the control group comparable placebo in a single-blinded fashion. The authors studied the occurrence of side effects and made attempts to judge their severity on a semi-quantitative visual analogue scale over a 2 months period starting after patients completed their first cycle of chemo- or radiotherapy, respectively. Twenty five radiotherapy patients receiving Pycnogenol showed a decreased frequency of essentially all investigated side-effects as compared to 21 patients receiving placebo, though in many categories the difference was limited. The most apparent improvements of acute side effects related to decreased soreness and ulceration in the mouth and throat as well as less dryness of the mouth and the eyes. A decreased incidence of nausea /vomiting, diarrhoea, edema and weakness was noticed, which was reflected by semi-quantitative evaluation suggesting that severity was only half or even less pronounced than in the control group. Only one case of deep vein thrombosis occurred in the Pycnogenol group whereas 2 cases of superficial vein thromboses and one case of deep vein thrombosis occurred in the control group (2.9% vs 10%). Thirty four chemotherapy patients were supplemented with Pycnogenol and another 30

  13. Tadalafil alleviates muscle ischemia in patients with Becker muscular dystrophy

    Science.gov (United States)

    Martin, Elizabeth A.; Barresi, Rita; Byrne, Barry J.; Tsimerinov, Evgeny I.; Scott, Bryan L.; Walker, Ashley E.; Gurudevan, Swaminatha V.; Anene, Francine; Elashoff, Robert M.; Thomas, Gail D.; Victor, Ronald G.

    2013-01-01

    Becker muscular dystrophy (BMD) is a progressive X-linked muscle wasting disease for which there is no treatment. Like Duchenne muscular dystrophy (DMD), BMD is caused by mutations in the gene encoding dystrophin, a structural cytoskeletal protein that also targets other proteins to the muscle sarcolemma. Among these is neuronal nitric oxide synthase (nNOSμ), which requires certain spectrin-like repeats in dystrophin’s rod domain and the adaptor protein α-syntrophin to be targeted to the sarcolemma. When healthy skeletal muscle is subjected to exercise, sarcolemmal nNOSμ-derived nitric oxide (NO) attenuates local α-adrenergic vasoconstriction thereby optimizing perfusion of muscle. We found previously that this protective mechanism is defective—causing functional muscle ischemia—in dystrophin-deficient muscles of the mdx mouse (a model of DMD) and of children with DMD, in whom nNOSμ is mislocalized to the cytosol instead of the sarcolemma. Here, we report that this protective mechanism also is defective in men with BMD in whom the most common dystrophin mutations disrupt sarcolemmal targeting of nNOSμ. In these men, the vasoconstrictor response, measured as a decrease in muscle oxygenation, to reflex sympathetic activation is not appropriately attenuated during exercise of the dystrophic muscles. In a randomized placebo-controlled cross-over trial, we show that functional muscle ischemia is alleviated and normal blood flow regulation fully restored in the muscles of men with BMD by boosting NO-cGMP signaling with a single dose of the drug tadalafil, a phosphodiesterase (PDE5A) inhibitor. These results further support an essential role for sarcolemmal nNOSμ in the normal modulation of sympathetic vasoconstriction in exercising human skeletal muscle and implicate the NO-cGMP pathway as a putative new target for treating BMD. PMID:23197572

  14. Tadalafil alleviates muscle ischemia in patients with Becker muscular dystrophy.

    Science.gov (United States)

    Martin, Elizabeth A; Barresi, Rita; Byrne, Barry J; Tsimerinov, Evgeny I; Scott, Bryan L; Walker, Ashley E; Gurudevan, Swaminatha V; Anene, Francine; Elashoff, Robert M; Thomas, Gail D; Victor, Ronald G

    2012-11-28

    Becker muscular dystrophy (BMD) is a progressive X-linked muscle wasting disease for which there is no treatment. Like Duchenne muscular dystrophy (DMD), BMD is caused by mutations in the gene encoding dystrophin, a structural cytoskeletal protein that also targets other proteins to the muscle sarcolemma. Among these is neuronal nitric oxide synthase (nNOSμ), which requires certain spectrin-like repeats in dystrophin's rod domain and the adaptor protein α-syntrophin to be targeted to the sarcolemma. When healthy skeletal muscle is subjected to exercise, sarcolemmal nNOSμ-derived NO attenuates local α-adrenergic vasoconstriction, thereby optimizing perfusion of muscle. We found previously that this protective mechanism is defective-causing functional muscle ischemia-in dystrophin-deficient muscles of the mdx mouse (a model of DMD) and of children with DMD, in whom nNOSμ is mislocalized to the cytosol instead of the sarcolemma. We report that this protective mechanism also is defective in men with BMD in whom the most common dystrophin mutations disrupt sarcolemmal targeting of nNOSμ. In these men, the vasoconstrictor response, measured as a decrease in muscle oxygenation, to reflex sympathetic activation is not appropriately attenuated during exercise of the dystrophic muscles. In a randomized placebo-controlled crossover trial, we show that functional muscle ischemia is alleviated and normal blood flow regulation is fully restored in the muscles of men with BMD by boosting NO-cGMP (guanosine 3',5'-monophosphate) signaling with a single dose of the drug tadalafil, a phosphodiesterase 5A inhibitor. These results further support an essential role for sarcolemmal nNOSμ in the normal modulation of sympathetic vasoconstriction in exercising human skeletal muscle and implicate the NO-cGMP pathway as a putative new target for treating BMD.

  15. Interstellar extinction in the Taurus dark clouds

    International Nuclear Information System (INIS)

    Meistas, E.; Straizys, V.

    1981-01-01

    The results of photoelectric photometry of 89 stars in the Vilnius seven-color system in the area of the Taurus dark clouds with corrdinates (1950) 4sup(h)16sup(m)-4sup(h)33sup(m), +16 0 -+20 0 are presented. Photometric spectral types, absolute magnitude, color excesses, interstellar extinctions and distances of the stars are determined. The distance of the dark nebula is found to be 140 pc and is in a good agreement with the distance determined for the dark nebula Khavtassi 286, 278. The average extinction Asub(v) in the investigated area is of the order of 1.4. (author)

  16. Narrowing down the conditions for extinction of Pavlovian feature-positive discriminations in humans.

    Science.gov (United States)

    van Vooren, Priya R; Franssen, Mathijs; Beckers, Tom; Hermans, Dirk; Baeyens, Frank

    2012-12-01

    The aim of this study was to delineate the minimal conditions for extinction of Pavlovian modulation in humans. Previous experiments at our lab showed that, after X-- A+/A- acquisition training, X- trials did not extinguish differential X-- A+/A- responding, while X-- A- trials did. Additionally, X-- A- extinction training seemed only to extinguish differential X-- A+/A- responding, while leaving differential responding on a concurrently trained Y [Symbol: see text] B+/B- discrimination intact. It thus seemed that the X-- A+/A- discrimination can only be extinguished by X-- A- extinction trials. (Rescorla, Journal of Experimental Psychology: Animal Behavior Processes 12, 16-24, 1986), on the other hand, found that the minimal conditions for extinction were broader in pigeons: Namely, he found that an acquired X-- A+/A- discrimination could be extinguished by presenting the original feature X in combination with a different target (B) that was minimally trained as an exciter. We thus wanted to examine whether this was also the case in humans. We found that nonreinforced X-- B- presentations did not abolish discriminative X-- A/A responding when target B was a nonreinforced stimulus. Nonreinforced X-- B- trials did extinguish the X-- A+/A- discrimination when target B had previously been trained as a target for modulation (X-- B+/B- or Y [Symbol: see text] B+/B- training) or as a reinforced exciter (B+). Our results thusf parallel and extend those in nonhuman animals (Rescorla, Journal of Experimental Psychology: Animal Behavior Processes 12, 16-24, 1986).

  17. Everolimus with reduced calcineurin inhibitor in thoracic transplant recipients with renal dysfunction: a multicenter, randomized trial

    DEFF Research Database (Denmark)

    Gullestad, Lars; Iversen, Martin; Mortensen, Svend-Aage

    2010-01-01

    The proliferation signal inhibitor everolimus offers the potential to reduce calcineurin inhibitor (CNI) exposure and alleviate CNI-related nephrotoxicity. Randomized trials in maintenance thoracic transplant patients are lacking.......The proliferation signal inhibitor everolimus offers the potential to reduce calcineurin inhibitor (CNI) exposure and alleviate CNI-related nephrotoxicity. Randomized trials in maintenance thoracic transplant patients are lacking....

  18. Can Earth Sciences Help Alleviate Global Poverty?

    Science.gov (United States)

    Mutter, J. C.

    2004-12-01

    essential and could hold the key to making gains toward alleviating the burden of global poverty.

  19. Inactivating the infralimbic but not prelimbic medial prefrontal cortex facilitates the extinction of appetitive Pavlovian conditioning in Long-Evans rats.

    Science.gov (United States)

    Mendoza, J; Sanio, C; Chaudhri, N

    2015-02-01

    The infralimbic medial prefrontal cortex (IL) has been posited as a common node in distinct neural circuits that mediate the extinction of appetitive and aversive conditioning. However, appetitive extinction is typically assessed using instrumental conditioning procedures, whereas the extinction of aversive conditioning is customarily studied using Pavlovian assays. The role of the IL in the extinction of appetitive Pavlovian conditioning remains underexplored. We investigated the involvement of the IL and prelimbic medial prefrontal cortex (PrL) in appetitive extinction in Pavlovian and instrumental conditioning assays in male, Long-Evans rats. Following acquisition, a gamma-aminobutyric acid agonist solution (0.03 nmol muscimol; 0.3 nmol baclofen; 0.3 μl/side) was bilaterally microinfused into the IL or PrL to pharmacologically inactivate each region before the first extinction session. Compared to saline, PrL inactivation did not affect the acquisition of extinction or the recall of extinction memory 24-h later. IL inactivation caused a more rapid extinction of Pavlovian conditioning, but had no effect on the extinction of instrumental conditioning or extinction recall. IL inactivation during a Pavlovian conditioning session in which conditioned stimulus (CS) trials were paired with sucrose did not affect CS-elicited behaviour, but increased responding during intervals that did not contain the CS. The same manipulation did not impact lever pressing for sucrose. These findings suggest that the IL may normally maintain Pavlovian conditioned responding when an anticipated appetitive CS is unexpectedly withheld, and that this region has distinct roles in the expression of Pavlovian conditioning when an appetitive unconditioned stimulus is either presented or omitted. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Effects of psilocybin on hippocampal neurogenesis and extinction of trace fear conditioning.

    Science.gov (United States)

    Catlow, Briony J; Song, Shijie; Paredes, Daniel A; Kirstein, Cheryl L; Sanchez-Ramos, Juan

    2013-08-01

    Drugs that modulate serotonin (5-HT) synaptic concentrations impact neurogenesis and hippocampal (HPC)-dependent learning. The primary objective is to determine the extent to which psilocybin (PSOP) modulates neurogenesis and thereby affects acquisition and extinction of HPC-dependent trace fear conditioning. PSOP, the 5-HT2A agonist 25I-NBMeO and the 5-HT2A/C antagonist ketanserin were administered via an acute intraperitoneal injection to mice. Trace fear conditioning was measured as the amount of time spent immobile in the presence of the conditioned stimulus (CS, auditory tone), trace (silent interval) and post-trace interval over 10 trials. Extinction was determined by the number of trials required to resume mobility during CS, trace and post-trace when the shock was not delivered. Neurogenesis was determined by unbiased counts of cells in the dentate gyrus of the HPC birth-dated with BrdU co-expressing a neuronal marker. Mice treated with a range of doses of PSOP acquired a robust conditioned fear response. Mice injected with low doses of PSOP extinguished cued fear conditioning significantly more rapidly than high-dose PSOP or saline-treated mice. Injection of PSOP, 25I-NBMeO or ketanserin resulted in significant dose-dependent decreases in number of newborn neurons in hippocampus. At the low doses of PSOP that enhanced extinction, neurogenesis was not decreased, but rather tended toward an increase. Extinction of "fear conditioning" may be mediated by actions of the drugs at sites other than hippocampus such as the amygdala, which is known to mediate the perception of fear. Another caveat is that PSOP is not purely selective for 5-HT2A receptors. PSOP facilitates extinction of the classically conditioned fear response, and this, and similar agents, should be explored as potential treatments for post-traumatic stress disorder and related conditions.

  1. Effect of Dry Season Tomato Farming on Poverty Alleviation among ...

    African Journals Online (AJOL)

    Effect of Dry Season Tomato Farming on Poverty Alleviation among Women ... their major sources of resources for tomato farming, marketing and marketing ... and the effect of dry season tomato farming as strategy for poverty reduction; ...

  2. Aqueous extract of Hibiscus sabdarrifa calyx alleviates anemia and ...

    African Journals Online (AJOL)

    Aqueous extract of Hibiscus sabdarrifa calyx alleviates anemia and organ damage in Trypanosoma brucei brucei infected rats. IA Umar, E Daikwo, NG Maryoms, A Gidado, LB Buratai, FS Saka, MA Ibrahim ...

  3. Phosphorus and humic acid application alleviate salinity stress of ...

    African Journals Online (AJOL)

    Phosphorus and humic acid application alleviate salinity stress of pepper seedling. ... It consequently affects plant growth and yield and ameliorates the deleterious effects of salt stress. The objective of the study ... from 32 Countries: Algeria (5) ...

  4. ULTRAVIOLET EXTINCTION AT HIGH GALACTIC LATITUDES

    Energy Technology Data Exchange (ETDEWEB)

    Peek, J. E. G.; Schiminovich, David, E-mail: jegpeek@gmail.com [Department of Astronomy, Columbia University, New York, NY (United States)

    2013-07-01

    In order to study the properties and effects of high Galactic latitude dust, we present an analysis of 373,303 galaxies selected from the Galaxy Evolution Explorer All-Sky Survey and Wide-field Infrared Explorer All-Sky Data Release. By examining the variation in aggregate ultraviolet colors and number density of these galaxies, we measure the extinction curve at high latitude. We additionally consider a population of spectroscopically selected galaxies from the Sloan Digital Sky Survey to measure extinction in the optical. We find that dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws. Extinction in the FUV and NUV is {approx}10% and {approx}35% higher than expected, with significant variation across the sky. We find that no single R{sub V} parameter fits both the optical and ultraviolet extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related. We propose that the overall trends we detect likely stem from an increase in very small silicate grains in the interstellar medium.

  5. The Neandertal extinction in eastern Central Europe

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jiří

    2005-01-01

    Roč. 137, - (2005), s. 69-75 ISSN 1040-6182 Institutional research plan: CEZ:AV0Z80010507 Keywords : Central Europe Neandertals * early modern humans * extinction Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 1.210, year: 2005

  6. ULTRAVIOLET EXTINCTION AT HIGH GALACTIC LATITUDES

    International Nuclear Information System (INIS)

    Peek, J. E. G.; Schiminovich, David

    2013-01-01

    In order to study the properties and effects of high Galactic latitude dust, we present an analysis of 373,303 galaxies selected from the Galaxy Evolution Explorer All-Sky Survey and Wide-field Infrared Explorer All-Sky Data Release. By examining the variation in aggregate ultraviolet colors and number density of these galaxies, we measure the extinction curve at high latitude. We additionally consider a population of spectroscopically selected galaxies from the Sloan Digital Sky Survey to measure extinction in the optical. We find that dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws. Extinction in the FUV and NUV is ∼10% and ∼35% higher than expected, with significant variation across the sky. We find that no single R V parameter fits both the optical and ultraviolet extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related. We propose that the overall trends we detect likely stem from an increase in very small silicate grains in the interstellar medium.

  7. Interstellar Extinction in the Gaia Photometric Systems

    Directory of Open Access Journals (Sweden)

    Bridžius A.

    2003-12-01

    Full Text Available Three medium-band photometric systems proposed for the Gaia space mission are intercompared in determining color excesses for stars of spectral classes from O to M at V = 18 mag. A possibility of obtaining a three-dimensional map of the interstellar extinction is discussed.

  8. Optical atmospheric extinction over Cerro Paranal

    NARCIS (Netherlands)

    Patat, F.; Moehler, S.; O'Brien, K.; Pompei, E.; Bensby, T.; Carraro, G.; de Ugarte Postigo, A.; Fox, A.; Gavignaud, I.; James, G.; Korhonen, H.; Ledoux, C.; Randall, S.; Sana, H.A.A.; Smoker, J.; Stefl, S.; Szeifert, T.

    2011-01-01

    Aims. The present study was conducted to determine the optical extinction curve for Cerro Paranal under typical clear-sky observing conditions, with the purpose of providing the community with a function to be used to correct the observed spectra, with an accuracy of 0.01 mag airmass-1.

  9. A new explanation of the extinction paradox

    International Nuclear Information System (INIS)

    Berg, M.J.; Sorensen, C.M.; Chakrabarti, A.

    2011-01-01

    This work presents a new explanation for the extinction paradox and shows that the canonical explanations are incorrect. This paradox refers to the large size limit of a particle's extinction cross section. It is called a paradox because the geometrical optics approximation, which should be valid in this limit, predicts a cross section that is half of the true value. The new explanation is achieved by formulating the scattered wave in terms of an integral over the particle's surface where the seemingly unrelated Ewald-Oseen theorem appears in the formulation. By expressing the cross section in terms of this surface integral, the Ewald-Oseen theorem is analytically connected to the cross section. Several illustrations are used to reveal the significance of this connection: The paradox is seen to be a consequence of the requirement that the incident wave be canceled within the particle by secondary radiation from its own internal field. Following this, the canonical explanations are examined to reveal serious problems. In the process, the same asymptotic extinction behavior is shown to occur for small highly refractive dielectric particles, and thus is not just a large particle size or small wavelength effect as is often stated. The traditional explanations cannot account for this behavior while the new one actually predicts it. All in all, this work constitutes a fundamental reworking of 60 years of accepted understanding for the cause of the asymptotic behavior of the extinction cross section.

  10. Time to extinction of bird populations

    NARCIS (Netherlands)

    Sæther, B-E.; Engen, S.; Møller, A.P.; Visser, M.E.; Matthysen, E.; Fiedler, W.; Lambrechts, M.M.; Becker, P.H.; Brommer, J.E.; Dickinson, J.; du Feu, C.; Gehlbach, F.R.; Merilä, J.; Rendell, W.; Robertson, R.J.; Thomson, D.L.; Török, J.

    2005-01-01

    The risk of extinction of populations has not previously been empirically related to parameters characterizing their population dynamics. To analyze this relationship, we simulated how the distribution of population dynamical characters changed as a function of time, in both the remaining and the

  11. Methylphenidate Enhances Extinction of Contextual Fear

    Science.gov (United States)

    Abraham, Antony D.; Cunningham, Christopher L.; Lattal, K. Matthew

    2012-01-01

    Methylphenidate (MPH, Ritalin) is a norepinephrine and dopamine transporter blocker that is widely used in humans for treatment of attention deficit disorder and narcolepsy. Although there is some evidence that targeted microinjections of MPH may enhance fear acquisition, little is known about the effect of MPH on fear extinction. Here, we show…

  12. Dust extinction in the first galaxies

    Science.gov (United States)

    Jaacks, Jason; Finkelstein, Steven L.; Bromm, Volker

    2018-04-01

    Using cosmological volume simulations and a custom built sub-grid model for Population III (Pop III) star formation, we examine the baseline dust extinction in the first galaxies due to Pop III metal enrichment in the first billion years of cosmic history. We find that although the most enriched, high-density lines of sight in primordial galaxies can experience a measurable amount of extinction from Pop III dust [E(B - V)max = 0.07, AV, max ≈ 0.28], the average extinction is very low with ≲ 10-3. We derive a power-law relationship between dark matter halo mass and extinction of E(B-V)∝ M_halo^{0.80}. Performing a Monte Carlo parameter study, we establish the baseline reddening of the ultraviolet spectra of dwarf galaxies at high redshift due to Pop III enrichment only. With this method, we find - 2.51 ± 0.07, which is both nearly halo mass and redshift independent.

  13. Stressor controllability modulates fear extinction in humans

    Science.gov (United States)

    Hartley, Catherine A.; Gorun, Alyson; Reddan, Marianne C.; Ramirez, Franchesca; Phelps, Elizabeth A.

    2014-01-01

    Traumatic events are proposed to play a role in the development of anxiety disorders, however not all individuals exposed to extreme stress experience a pathological increase in fear. Recent studies in animal models suggest that the degree to which one is able to control an aversive experience is a critical factor determining its behavioral consequences. In this study, we examined whether stressor controllability modulates subsequent conditioned fear expression in humans. Participants were randomly assigned to an escapable stressor condition, a yoked inescapable stressor condition, or a control condition involving no stress exposure. One week later, all participants underwent fear conditioning, fear extinction, and a test of extinction retrieval the following day. Participants exposed to inescapable stress showed impaired fear extinction learning and increased fear expression the following day. In contrast, escapable stress improved fear extinction and prevented the spontaneous recovery of fear. Consistent with the bidirectional controllability effects previously reported in animal models, these results suggest that one's degree of control over aversive experiences may be an important factor influencing the development of psychological resilience or vulnerability in humans. PMID:24333646

  14. Biological hierarchies and the nature of extinction.

    Science.gov (United States)

    Congreve, Curtis R; Falk, Amanda R; Lamsdell, James C

    2018-05-01

    Hierarchy theory recognises that ecological and evolutionary units occur in a nested and interconnected hierarchical system, with cascading effects occurring between hierarchical levels. Different biological disciplines have routinely come into conflict over the primacy of different forcing mechanisms behind evolutionary and ecological change. These disconnects arise partly from differences in perspective (with some researchers favouring ecological forcing mechanisms while others favour developmental/historical mechanisms), as well as differences in the temporal framework in which workers operate. In particular, long-term palaeontological data often show that large-scale (macro) patterns of evolution are predominantly dictated by shifts in the abiotic environment, while short-term (micro) modern biological studies stress the importance of biotic interactions. We propose that thinking about ecological and evolutionary interactions in a hierarchical framework is a fruitful way to resolve these conflicts. Hierarchy theory suggests that changes occurring at lower hierarchical levels can have unexpected, complex effects at higher scales due to emergent interactions between simple systems. In this way, patterns occurring on short- and long-term time scales are equally valid, as changes that are driven from lower levels will manifest in different forms at higher levels. We propose that the dual hierarchy framework fits well with our current understanding of evolutionary and ecological theory. Furthermore, we describe how this framework can be used to understand major extinction events better. Multi-generational attritional loss of reproductive fitness (MALF) has recently been proposed as the primary mechanism behind extinction events, whereby extinction is explainable solely through processes that result in extirpation of populations through a shutdown of reproduction. While not necessarily explicit, the push to explain extinction through solely population-level dynamics

  15. Biogeographic and bathymetric determinants of brachiopod extinction and survival during the Late Ordovician mass extinction

    DEFF Research Database (Denmark)

    Finnegan, Seth; Mac Ørum Rasmussen, Christian; Harper, David A. T.

    2016-01-01

    –Early Silurian genus extinctions and evaluate which extinction drivers are best supported by the data. The first (latest Katian) pulse of the LOME preferentially affected genera restricted to deeper waters or to relatively narrow (less than 35°) palaeolatitudinal ranges. This pattern is only observed...... in the latest Katian, suggesting that it reflects drivers unique to this interval. Extinction of exclusively deeper-water genera implies that changes in water mass properties such as dissolved oxygen content played an important role. Extinction of genera with narrow latitudinal ranges suggests that interactions...... between shifting climate zones and palaeobiogeography may also have been important. We test the latter hypothesis by estimating whether each genus would have been able to track habitats within its thermal tolerance range during the greenhouse–icehouse climate transition. Models including these estimates...

  16. Endangered Species and Natural Resource Exploitation: Extinction vs. Coexistence

    OpenAIRE

    Tsur, Yacov; Zemel, Amos

    1994-01-01

    The threat on the survival of animal species due to intensive use of natural resources is incorporated within resource management models, paying special attention to uncertainty regarding the conditions that lead to extinction. The manner in which the potential benefits forgone due to the species extinction (denoted extinction penalty) induce more conservative exploitation policies is studied in detail. When the extinction penalty is ignored, the optimal policy is to drive the resource stock ...

  17. Extinction models for cancer stem cell therapy

    Science.gov (United States)

    Sehl, Mary; Zhou, Hua; Sinsheimer, Janet S.; Lange, Kenneth L.

    2012-01-01

    Cells with stem cell-like properties are now viewed as initiating and sustaining many cancers. This suggests that cancer can be cured by driving these cancer stem cells to extinction. The problem with this strategy is that ordinary stem cells are apt to be killed in the process. This paper sets bounds on the killing differential (difference between death rates of cancer stem cells and normal stem cells) that must exist for the survival of an adequate number of normal stem cells. Our main tools are birth–death Markov chains in continuous time. In this framework, we investigate the extinction times of cancer stem cells and normal stem cells. Application of extreme value theory from mathematical statistics yields an accurate asymptotic distribution and corresponding moments for both extinction times. We compare these distributions for the two cell populations as a function of the killing rates. Perhaps a more telling comparison involves the number of normal stem cells NH at the extinction time of the cancer stem cells. Conditioning on the asymptotic time to extinction of the cancer stem cells allows us to calculate the asymptotic mean and variance of NH. The full distribution of NH can be retrieved by the finite Fourier transform and, in some parameter regimes, by an eigenfunction expansion. Finally, we discuss the impact of quiescence (the resting state) on stem cell dynamics. Quiescence can act as a sanctuary for cancer stem cells and imperils the proposed therapy. We approach the complication of quiescence via multitype branching process models and stochastic simulation. Improvements to the τ-leaping method of stochastic simulation make it a versatile tool in this context. We conclude that the proposed therapy must target quiescent cancer stem cells as well as actively dividing cancer stem cells. The current cancer models demonstrate the virtue of attacking the same quantitative questions from a variety of modeling, mathematical, and computational perspectives

  18. Malthusian Catastrophe: Species Extinction Caused By Oversized Population

    OpenAIRE

    Pan, Xubin

    2017-01-01

    There is one pseudo-extinction debt and four occurring conditions for real extinction debt. Since small and oversized populations have a high extinction risk, Pan threshold (upper limit) was calculated for Verhulst-Pear logistic growth model and logistic model with the Allee effect, an important parameter corresponding to Allee threshold (lower limit).

  19. Fibroblast Growth Factor-2 Alters the Nature of Extinction

    Science.gov (United States)

    Graham, Bronwyn M.; Richardson, Rick

    2011-01-01

    These experiments examined the effects of the NMDA-receptor (NMDAr) antagonist MK801 on reacquisition and re-extinction of a conditioned fear that had been previously extinguished before injection of fibroblast growth factor-2 (FGF2) or vehicle. Recent findings have shown that relearning and re-extinction, unlike initial learning and extinction,…

  20. Inhibition of Estradiol Synthesis Impairs Fear Extinction in Male Rats

    Science.gov (United States)

    Graham, Bronwyn M.; Milad, Mohammed R.

    2014-01-01

    Emerging research has demonstrated that the sex hormone estradiol regulates fear extinction in female rodents and women. Estradiol may also regulate fear extinction in males, given its role in synaptic plasticity in both sexes. Here we report that inhibition of estradiol synthesis during extinction training, via the aromatase inhibitor fadrozole,…

  1. Slower Reacquisition after Partial Extinction in Human Contingency Learning

    Science.gov (United States)

    Morís, Joaquín; Barberia, Itxaso; Vadillo, Miguel A.; Andrades, Ainhoa; López, Francisco J.

    2017-01-01

    Extinction is a very relevant learning phenomenon from a theoretical and applied point of view. One of its most relevant features is that relapse phenomena often take place once the extinction training has been completed. Accordingly, as extinction-based therapies constitute the most widespread empirically validated treatment of anxiety disorders,…

  2. A study of the fundamental characteristics of 2175A extinction

    Science.gov (United States)

    Cardelli, Jason A.; Savage, Blair D.

    1987-01-01

    The characteristics of interstellar extinction were studied in the region of the 2175 A feature for lines of sight which appear to exhibit unusually weak ultraviolet extinction. The analysis was based upon a parameterization of the observed extinction via fitting specific mathematical functions in order to determine the position and width of the 2175 A feature. The data are currently being analyzed.

  3. Selecting for extinction: nonrandom disease-associated extinction homogenizes amphibian biotas.

    Science.gov (United States)

    Smith, Kevin G; Lips, Karen R; Chase, Jonathan M

    2009-10-01

    Studying the patterns in which local extinctions occur is critical to understanding how extinctions affect biodiversity at local, regional and global spatial scales. To understand the importance of patterns of extinction at a regional spatial scale, we use data from extirpations associated with a widespread pathogenic agent of amphibian decline, Batrachochytrium dendrobatidis (Bd) as a model system. We apply novel null model analyses to these data to determine whether recent extirpations associated with Bd have resulted in selective extinction and homogenization of diverse tropical American amphibian biotas. We find that Bd-associated extinctions in this region were nonrandom and disproportionately, but not exclusively, affected low-occupancy and endemic species, resulting in homogenization of the remnant amphibian fauna. The pattern of extirpations also resulted in phylogenetic homogenization at the family level and ecological homogenization of reproductive mode and habitat association. Additionally, many more species were extirpated from the region than would be expected if extirpations occurred randomly. Our results indicate that amphibian declines in this region are an extinction filter, reducing regional amphibian biodiversity to highly similar relict assemblages and ultimately causing amplified biodiversity loss at regional and global scales.

  4. Learning deficits expressed as delayed extinction of a conditioned running response following perinatal exposure to vinclozolin.

    Science.gov (United States)

    André, Susan M; Markowski, Vincent P

    2006-01-01

    Vinclozolin (Vz) is one member of a group of fungicides whose metabolites are androgen receptor antagonists. These fungicides have been shown to block androgen-driven development and compromise reproductive function. The current study sought to determine if Vz also affects learning following exposure to low doses during the perinatal period. To test this, an androgen-dependent behavior was examined, the extinction of a previously reinforced running response. Pregnant Long-Evans rats were administered a daily oral dose of 0, 1.5, 3, 6 or 12 mg/kg Vz from the 14th day of gestation through postnatal day 3. After reaching adulthood, male and female offspring were trained to run through a short alleyway for food reinforcement. Acquisition of the response was not affected by Vz exposure. However, males required more trials than females for response extinction once food was no longer available in the apparatus. Males exposed to 6 or 12 mg/kg Vz failed to show any extinction by the end of the procedure, while the lowest dose of Vz appeared to facilitate extinction in both male and female offspring. These results demonstrate that endocrine disrupting antiandrogens can alter nervous system development in addition to the reproductive system.

  5. Effects of Depression Alleviation on ART Adherence and HIV Clinic Attendance in Uganda, and the Mediating Roles of Self-Efficacy and Motivation.

    Science.gov (United States)

    Wagner, Glenn J; Ghosh-Dastidar, Bonnie; Robinson, Eric; Ngo, Victoria K; Glick, Peter; Mukasa, Barbara; Musisi, Seggane; Akena, Dickens

    2017-06-01

    With depression known to impede HIV care adherence and retention, we examined whether depression alleviation improves these disease management behaviors. A sample of 1028 depressed HIV clients in Uganda enrolled in a cluster randomized controlled trial of two depression care models, and were surveyed over 12 months. Serial regression analyses examined whether depression alleviation was associated with self-reported antiretroviral therapy (ART) adherence and clinic attendance at month 12, and whether these relationships were mediated by self-efficacy and motivation. Among those with major depression, depression alleviation was associated with better ART adherence and clinic attendance at month 12; these relationships were fully mediated by self-efficacy at month 12, while adherence motivation partially mediated the relationship between depression alleviation and ART adherence. When both mediators were entered simultaneously, only self-efficacy was a significant predictor and still fully mediated the relationship between depression alleviation and adherence. These findings suggest that depression alleviation benefits both ART adherence and clinic attendance, in large part through improved confidence and motivation to engage in these disease management behaviors.

  6. Decline and local extinction of Fucales in French Riviera: the harbinger of future extinctions?

    Directory of Open Access Journals (Sweden)

    T. THIBAUT

    2014-03-01

    Full Text Available The French Riviera is one of the Mediterranean areas that has been longest and most thoroughly impacted by human activities. Fucales are long-lived, large-sized brown algae that constitute a good model for studying human impact on species diversity. We gathered all historical data (literature and herbarium vouchers, since the early 19th century, to reconstruct their distribution. The current distribution was established from a 7-year (2007-2013 survey of the 212-km shoreline (1/2 500 map, by means of boating, snorkelling and scuba diving. Overall, 18 taxa of Cystoseira and Sargassum have been reported. Upon comparison with historical data, 5 taxa were no longer observed (C. elegans, C. foeniculacea f. latiramosa, C. squarrosa, C. spinosa var. spinosa and S. hornschuchii while C. jabukae, previously unrecorded, was observed. In addition to these  taxa, probably extinct at a local scale, some taxa had suffered a dramatic decline (C. barbata f. barbata, C. crinita, C. spinosa var. compressa and S. acinarium or become nearly extinct (C. foeniculacea f. tenuiramosa. Three of them, which played in the past significant functional roles in coastal communities, can be considered as functionally extinct. Possible causes of decline and local extinction are discussed. A similar situation has already been reported, although at a much more local scale, in a variety of Mediterranean localities. The question therefore arises about the status of Fucales species in the Mediterranean: are some species on the brink of extinction? Is their extinction at the scale of the French Riviera the harbinger of their extinction Mediterranean–wide?

  7. Reactivated Memories Compete for Expression After Pavlovian Extinction

    Science.gov (United States)

    Laborda, Mario A.; Miller, Ralph R.

    2012-01-01

    We view the response decrement resulting from extinction treatment as an interference effect, in which the reactivated memory from acquisition competes with the reactivated memory from extinction for behavioral expression. For each of these memories, reactivation is proportional to both the strength of the stimulus-outcome association and the quality of the facilitatory cues for that association which are present at test. Here we review basic extinction and recovery-from-extinction phenomena, showing how these effects are explicable in this associative interference framework. Moreover, this orientation has and continues to dictate efficient manipulations for minimizing recovery from extinction. This in turn suggests procedures that might reduce relapse from exposure therapy for a number of psychological disorders. Some of these manipulations enhance the facilitatory cues from extinction that are present at test, others strengthen the extinction association (i.e., CS-no outcome), and yet others seem to work by a combination of these two processes. PMID:22326812

  8. Running from fear: Exercise modulation of fear extinction.

    Science.gov (United States)

    Tanner, Margaret K; Hake, Holly S; Bouchet, Courtney A; Greenwood, Benjamin N

    2018-03-31

    Extinction-based exposure therapy is the most common behavioral therapy for anxiety and trauma-related disorders, but fear tends to resurface even after successful extinction. Identification of novel strategies to enhance fear extinction and reduce fear relapse is of paramount importance to mental health. Exercise can enhance cognitive function, but it is not yet well understood whether exercise can be an effective augmentation strategy for fear extinction. In the current review, we present the current state of knowledge on the effects of exercise on fear extinction. Effects of exercise duration, explanations for conflicting results, and potential mechanisms, focusing on a hypothesized role for dopamine, are all discussed. We also provide new data suggesting that the timing in which acute exercise occurs relative to fear extinction, is a crucial variable in determining whether exercise can enhance fear extinction. Clinical implications and ideas to guide future research endeavors in this area are provided. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. A global synthesis of plant extinction rates in urban areas.

    Science.gov (United States)

    Hahs, Amy K; McDonnell, Mark J; McCarthy, Michael A; Vesk, Peter A; Corlett, Richard T; Norton, Briony A; Clemants, Steven E; Duncan, Richard P; Thompson, Ken; Schwartz, Mark W; Williams, Nicholas S G

    2009-11-01

    Plant extinctions from urban areas are a growing threat to biodiversity worldwide. To minimize this threat, it is critical to understand what factors are influencing plant extinction rates. We compiled plant extinction rate data for 22 cities around the world. Two-thirds of the variation in plant extinction rates was explained by a combination of the city's historical development and the current proportion of native vegetation, with the former explaining the greatest variability. As a single variable, the amount of native vegetation remaining also influenced extinction rates, particularly in cities > 200 years old. Our study demonstrates that the legacies of landscape transformations by agrarian and urban development last for hundreds of years, and modern cities potentially carry a large extinction debt. This finding highlights the importance of preserving native vegetation in urban areas and the need for mitigation to minimize potential plant extinctions in the future.

  10. Role of the hippocampus in contextual modulation of fear extinction

    Institute of Scientific and Technical Information of China (English)

    Lingzhi Kong; Xihong Wu; Liang Li

    2008-01-01

    Fear extinction is an important form of emotional learning, and affects neural plasticity. Cue fear extinction is a classical form of inhibitory learning that can be used as an exposure-based treatment for phobia, because the long-term extinction memory produced during cue fear extinction can limit the over-expression of fear. The expression of this inhibitory memory partly depends on the context in which the extinction learning occurs. Studies such as transient inhibition, electrophysiology and brain imaging have proved that the hippocampus - an important structure in the limbic system - facilitates memory retrieval by contextual cues.Mediation of the hippocampus-medial prefrontal lobe circuit may be the neurobiological basis of this process.This article has reviewed the role of the hippocampus in the learning and retrieval of fear extinction.Contextual modulation of fear extinction may rely on a neural network consisting of the hippocampus, the medial prefrontal cortex and the amygdala.

  11. Epidemic extinction paths in complex networks

    Science.gov (United States)

    Hindes, Jason; Schwartz, Ira B.

    2017-05-01

    We study the extinction of long-lived epidemics on finite complex networks induced by intrinsic noise. Applying analytical techniques to the stochastic susceptible-infected-susceptible model, we predict the distribution of large fluctuations, the most probable or optimal path through a network that leads to a disease-free state from an endemic state, and the average extinction time in general configurations. Our predictions agree with Monte Carlo simulations on several networks, including synthetic weighted and degree-distributed networks with degree correlations, and an empirical high school contact network. In addition, our approach quantifies characteristic scaling patterns for the optimal path and distribution of large fluctuations, both near and away from the epidemic threshold, in networks with heterogeneous eigenvector centrality and degree distributions.

  12. Extinction of corrugated hydrogen/air flames

    International Nuclear Information System (INIS)

    Mizomoto, M.; Asaka, Y.; Ikai, S.; Law, C.K.

    1982-01-01

    Recent studies on flammability limits reveal the importance of flow nonuniformity, flame curvature, and molecular and thermal diffusivities in determining the extinguishability and the associated limits of premixed fuel/air flames. In particular, it is found that conditions which favor extinction of a lean flame may cause intensification of a rich flame. In the present study the authors have experimentally determined the extinction characteristics and limits of highly curved hydrogen/air flames as represented by the opening of bunsen flame tips. Results show that the tip opens at a constant fuel equivalence ratio of phi = 1.15, regardless of the velocity and uniformity of the upstream flow. This critical mixture concentration, while being rich, is still on the lean side of that corresponding to the maximum burning velocity (phi = 1.8), implying that for highly diffusive systems, the relevant reference concentration is that for maximum burning velocity instead of stoichiometry

  13. The galactic extinction towards Maffei 1

    International Nuclear Information System (INIS)

    Buta, R.J.; McCall, M.L.; McDonald Observatory, Austin, TX; Australian National Univ., Canberra. Mount Stromlo and Siding Spring Observatories)

    1983-01-01

    The extinction of Maffei 1 has been measured by two new techniques. First, BV aperture photometry has been performed to obtain the colour excess from standard aperture-colour relations for early-type galaxies. Secondly, millimetre and radio observations of galactic CO and HI have been used to calculate the total hydrogen column density along the line-of-sight, and thereby estimate the colour excess from the local dust-to-gas ratio. After consideration of all extinction measurements to date, it is concluded that Asub(v)=5.1+-0.2 mag. The isophotal diameter and the corrected apparent visual magnitude are estimated to be approx. 15 arcmin and approx. 6.3 respectively (assuming type E), making Maffei 1 one of the biggest and brightest galaxies in the sky. (author)

  14. Extinction risk under coloured environmental noise

    OpenAIRE

    Heino, M; Ripa, Jörgen; Kaitala, V

    2000-01-01

    Positively autocorrelated red environmental noise is characterized by a strong dependence of expected sample variance on sample length. This dependence has to be taken into account when assessing extinction risk under red and white uncorrelated environmental noise. To facilitate a comparison between red and white noise, their expected variances can be scaled to be equal, but only at a chosen time scale. We show with a simple one-dimensional population dynamics model that the different but equ...

  15. Immunological systematics of the extinct quagga (Equidae).

    Science.gov (United States)

    Lowenstein, J M; Ryder, O A

    1985-09-15

    It has been debated whether the extinct quagga was a distinct fourth species of African zebra or whether it was merely the southern variant of the Plains zebra (Equus burchelli). Using a radioimmunoassay (RIA) technique, we have shown that proteins remaining in quagga skins from museums are much more similar to serum proteins of the Plains zebra than to those of the other two extant zebras.

  16. Rewinding the process of mammalian extinction

    OpenAIRE

    Saragusty, J.; Diecke, S.; Drukker, M.; Durrant, B.; Friedrich Ben-Nun, I.; Galli, C.; Goeritz, F.; Hayashi, K.; Hermes, R.; Holtze, S.; Johnson, S.; Lazzari, G.; Loi, P.; Loring, J.F.; Okita, K.

    2016-01-01

    With only three living individuals left on this planet, the northern white rhinoceros (Ceratotherium simum cottoni) could be considered doomed for extinction. It might still be possible, however, to rescue the (sub)species by combining novel stem cell and assisted reproductive technologies. To discuss the various practical options available to us, we convened a multidisciplinary meeting under the name "Conservation by Cellular Technologies." The outcome of this meeting and the proposed road m...

  17. Opportunities and costs for preventing vertebrate extinctions.

    Science.gov (United States)

    Conde, Dalia A; Colchero, Fernando; Güneralp, Burak; Gusset, Markus; Skolnik, Ben; Parr, Michael; Byers, Onnie; Johnson, Kevin; Young, Glyn; Flesness, Nate; Possingham, Hugh; Fa, John E

    2015-03-16

    Despite an increase in policy and management responses to the global biodiversity crisis, implementation of the 20 Aichi Biodiversity Targets still shows insufficient progress [1]. These targets, strategic goals defined by the United Nations Convention on Biological Diversity (CBD), address major causes of biodiversity loss in part by establishing protected areas (Target 11) and preventing species extinctions (Target 12). To achieve this, increased interventions will be required for a large number of sites and species. The Alliance for Zero Extinction (AZE) [2], a consortium of conservation-oriented organisations that aims to protect Critically Endangered and Endangered species restricted to single sites, has identified 920 species of mammals, birds, amphibians, reptiles, conifers and reef-building corals in 588 'trigger' sites [3]. These are arguably the most irreplaceable category of important biodiversity conservation sites. Protected area coverage of AZE sites is a key indicator of progress towards Target 11 [1]. Moreover, effective conservation of AZE sites is essential to achieve Target 12, as the loss of any of these sites would certainly result in the global extinction of at least one species [2]. However, averting human-induced species extinctions within AZE sites requires enhanced planning tools to increase the chances of success [3]. Here, we assess the potential for ensuring the long-term conservation of AZE vertebrate species (157 mammals, 165 birds, 17 reptiles and 502 amphibians) by calculating a conservation opportunity index (COI) for each species. The COI encompasses a set of measurable indicators that quantify the possibility of achieving successful conservation of a species in its natural habitat (COIh) and by establishing insurance populations in zoos (COIc). Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Parrots and macaws: Species in extinction danger?

    International Nuclear Information System (INIS)

    Castro ramirez, Jose; Moyano P, Edgar A

    1994-01-01

    The paper refers to the privileged position of Colombia due to their position in the tropic, the influence of two oceans, their wide hydrographic net, variety of climates, etc; they make that Colombia occupies first places in biodiversity; but due to the indiscriminate pruning of primary forest, they make that this enormous biological potential is seriously threatened, where many of its birds are in extinction road

  19. Pathways to extinction: beyond the error threshold.

    Science.gov (United States)

    Manrubia, Susanna C; Domingo, Esteban; Lázaro, Ester

    2010-06-27

    Since the introduction of the quasispecies and the error catastrophe concepts for molecular evolution by Eigen and their subsequent application to viral populations, increased mutagenesis has become a common strategy to cause the extinction of viral infectivity. Nevertheless, the high complexity of virus populations has shown that viral extinction can occur through several other pathways apart from crossing an error threshold. Increases in the mutation rate enhance the appearance of defective forms and promote the selection of mechanisms that are able to counteract the accelerated appearance of mutations. Current models of viral evolution take into account more realistic scenarios that consider compensatory and lethal mutations, a highly redundant genotype-to-phenotype map, rough fitness landscapes relating phenotype and fitness, and where phenotype is described as a set of interdependent traits. Further, viral populations cannot be understood without specifying the characteristics of the environment where they evolve and adapt. Altogether, it turns out that the pathways through which viral quasispecies go extinct are multiple and diverse.

  20. Interstellar Extinction in 20 Open Star Clusters

    Science.gov (United States)

    Rangwal, Geeta; Yadav, R. K. S.; Durgapal, Alok K.; Bisht, D.

    2017-12-01

    The interstellar extinction law in 20 open star clusters namely, Berkeley 7, Collinder 69, Hogg 10, NGC 2362, Czernik 43, NGC 6530, NGC 6871, Bochum 10, Haffner 18, IC 4996, NGC 2384, NGC 6193, NGC 6618, NGC 7160, Collinder 232, Haffner 19, NGC 2401, NGC 6231, NGC 6823, and NGC 7380 have been studied in the optical and near-IR wavelength ranges. The difference between maximum and minimum values of E(B - V) indicates the presence of non-uniform extinction in all the clusters except Collinder 69, NGC 2362, and NGC 2384. The colour excess ratios are consistent with a normal extinction law for the clusters NGC 6823, Haffner 18, Haffner 19, NGC 7160, NGC 6193, NGC 2401, NGC 2384, NGC 6871, NGC 7380, Berkeley 7, Collinder 69, and IC 4996. We have found that the differential colour-excess ΔE(B - V), which may be due to the occurrence of dust and gas inside the clusters, decreases with the age of the clusters. A spatial variation of colour excess is found in NGC 6193 in the sense that it decreases from east to west in the cluster region. For the clusters Berkeley 7, NGC 7380, and NGC 6871, a dependence of colour excess E(B - V) with spectral class and luminosity is observed. Eight stars in Collinder 232, four stars in NGC 6530, and one star in NGC 6231 have excess flux in near-IR. This indicates that these stars may have circumstellar material around them.

  1. Mathematical Modeling of Extinction of Inhomogeneous Populations

    Science.gov (United States)

    Karev, G.P.; Kareva, I.

    2016-01-01

    Mathematical models of population extinction have a variety of applications in such areas as ecology, paleontology and conservation biology. Here we propose and investigate two types of sub-exponential models of population extinction. Unlike the more traditional exponential models, the life duration of sub-exponential models is finite. In the first model, the population is assumed to be composed clones that are independent from each other. In the second model, we assume that the size of the population as a whole decreases according to the sub-exponential equation. We then investigate the “unobserved heterogeneity”, i.e. the underlying inhomogeneous population model, and calculate the distribution of frequencies of clones for both models. We show that the dynamics of frequencies in the first model is governed by the principle of minimum of Tsallis information loss. In the second model, the notion of “internal population time” is proposed; with respect to the internal time, the dynamics of frequencies is governed by the principle of minimum of Shannon information loss. The results of this analysis show that the principle of minimum of information loss is the underlying law for the evolution of a broad class of models of population extinction. Finally, we propose a possible application of this modeling framework to mechanisms underlying time perception. PMID:27090117

  2. Area-based assessment of extinction risk.

    Science.gov (United States)

    Hei, Fangliang

    2012-05-01

    Underpinning the International Union for Conservation of Nature (IUCN) Red List is the assessment of extinction risk as determined by the size and degree of loss of populations. The IUCN system lists a species as Critically Endangered, Endangered, or Vulnerable if its population size declines 80%, 50%, or 30% within a given time frame. However, effective implementation of the system faces substantial challenges and uncertainty because geographic scale data on population size and long-term dynamics are scarce. I develop a model to quantify extinction risk using a measure based on a species' distribution, a much more readily obtained quantity. The model calculates the loss of the area of occupancy that is equivalent to the loss of a given proportion of a population. It is a very simple yet general model that has no free parameters and is independent of scale. The model predicted well the distributions of 302 tree species at a local scale and the distributions of 348 species of North American land birds. This area-based model provides a solution to the long-standing problem for IUCN assessments of lack of data on population sizes, and thus it will contribute to facilitating the quantification of extinction risk worldwide.

  3. Permo-Triassic vertebrate extinctions: A program

    Science.gov (United States)

    Olson, E. C.

    1988-01-01

    Since the time of the Authors' study on this subject, a great deal of new information has become available. Concepts of the nature of extinctions have changed materially. The Authors' conclusion that a catastrophic event was not responsible for the extinction of vertebrates has modified to the extent that hypotheses involving either the impact of a massive extra-terrestrial body or volcanism provide plausible but not currently fully testable hypotheses. Stated changes resulted in a rapid decrease in organic diversity, as the ratio of origins of taxa to extinctions shifted from strongly positive to negative, with momentary equilibrium being reached at about the Permo-Triassic boundary. The proximate causes of the changes in the terrestrial biota appear to lie in two primary factors: (1) strong climatic changes (global mean temperatures, temperature ranges, humidity) and (2) susceptibility of the dominant vertebrates (large dicynodonts) and the glossopteris flora to disruption of the equlibrium of the world ecosystem. The following proximate causes have been proposed: (1) rhythmic fluctuations in solar radiation, (2) tectonic events as Pangea assembled, altering land-ocean relationships, patterns of wind and water circulation and continental physiography, (3) volcanism, and (4) changes subsequent to impacts of one or more massive extra terrestrial objects, bodies or comets. These hypotheses are discussed.

  4. Rewinding the process of mammalian extinction.

    Science.gov (United States)

    Saragusty, Joseph; Diecke, Sebastian; Drukker, Micha; Durrant, Barbara; Friedrich Ben-Nun, Inbar; Galli, Cesare; Göritz, Frank; Hayashi, Katsuhiko; Hermes, Robert; Holtze, Susanne; Johnson, Stacey; Lazzari, Giovanna; Loi, Pasqualino; Loring, Jeanne F; Okita, Keisuke; Renfree, Marilyn B; Seet, Steven; Voracek, Thomas; Stejskal, Jan; Ryder, Oliver A; Hildebrandt, Thomas B

    2016-07-01

    With only three living individuals left on this planet, the northern white rhinoceros (Ceratotherium simum cottoni) could be considered doomed for extinction. It might still be possible, however, to rescue the (sub)species by combining novel stem cell and assisted reproductive technologies. To discuss the various practical options available to us, we convened a multidisciplinary meeting under the name "Conservation by Cellular Technologies." The outcome of this meeting and the proposed road map that, if successfully implemented, would ultimately lead to a self-sustaining population of an extremely endangered species are outlined here. The ideas discussed here, while centered on the northern white rhinoceros, are equally applicable, after proper adjustments, to other mammals on the brink of extinction. Through implementation of these ideas we hope to establish the foundation for reversal of some of the effects of what has been termed the sixth mass extinction event in the history of Earth, and the first anthropogenic one. Zoo Biol. 35:280-292, 2016. © 2016 The Authors. Zoo Biology published by Wiley Periodicals, Inc. © 2016 The Authors. Zoo Biology published by Wiley Periodicals, Inc.

  5. Causes and timing of future biosphere extinctions

    Directory of Open Access Journals (Sweden)

    S. Franck

    2006-01-01

    Full Text Available We present a minimal model for the global carbon cycle of the Earth containing the reservoirs mantle, ocean floor, continental crust, biosphere, and the kerogen, as well as the combined ocean and atmosphere reservoir. The model is specified by introducing three different types of biosphere: procaryotes, eucaryotes, and complex multicellular life. During the entire existence of the biosphere procaryotes are always present. 2 Gyr ago eucaryotic life first appears. The emergence of complex multicellular life is connected with an explosive increase in biomass and a strong decrease in Cambrian global surface temperature at about 0.54 Gyr ago. In the long-term future the three types of biosphere will die out in reverse sequence of their appearance. We show that there is no evidence for an implosion-like extinction in contrast to the Cambrian explosion. In dependence of their temperature tolerance complex multicellular life and eucaryotes become extinct in about 0.8–1.2 Gyr and 1.3–1.5 Gyr, respectively. The ultimate life span of the biosphere is defined by the extinction of procaryotes in about 1.6 Gyr.

  6. Interstellar extinction and polarization in the infrared

    International Nuclear Information System (INIS)

    Martin, P.G.; Whittet, D.C.B.

    1990-01-01

    The wavelength dependences of interstellar continuum extinction and polarization in the range 0.35-5 microns are examined. The existence of a universal extinction curve with power law index of about 1.8 extending from the near-IR to at least 5 microns appears to be established for both diffuse and dense cloud dust. The polarization yields evidence for some degree of universality in the 1.6-5 micron regime which may be represented by a power law with index 1.5-2.0, encompassing that for extinction. The form of the polarization curve in the IR seems independent of the wavelength at which the degree of polarization peaks in the optical, implying that variations in that wavelength are caused by changes in the optical properties of the particle at blue-visible rather than IR wavelengths. It is argued that the more significant alterations of the grain size distribution from one environment to another occur for the smaller particles. 47 refs

  7. High speed ultra-broadband amplitude modulators with ultrahigh extinction >65 dB.

    Science.gov (United States)

    Liu, S; Cai, H; DeRose, C T; Davids, P; Pomerene, A; Starbuck, A L; Trotter, D C; Camacho, R; Urayama, J; Lentine, A

    2017-05-15

    We experimentally demonstrate ultrahigh extinction ratio (>65 dB) amplitude modulators (AMs) that can be electrically tuned to operate across a broad spectral range of 160 nm from 1480 - 1640 nm and 95 nm from 1280 - 1375 nm. Our on-chip AMs employ one extra coupler compared with conventional Mach-Zehnder interferometers (MZI), thus form a cascaded MZI (CMZI) structure. Either directional or adiabatic couplers are used to compose the CMZI AMs and experimental comparisons are made between these two different structures. We investigate the performance of CMZI AMs under extreme conditions such as using 95:5 split ratio couplers and unbalanced waveguide losses. Electro-optic phase shifters are also integrated in the CMZI AMs for high-speed operation. Finally, we investigate the output optical phase when the amplitude is modulated, which provides us valuable information when both amplitude and phase are to be controlled. Our demonstration not only paves the road to applications such as quantum information processing that requires high extinction ratio AMs but also significantly alleviates the tight fabrication tolerance needed for large-scale integrated photonics.

  8. AN ANALYSIS OF THE SHAPES OF INTERSTELLAR EXTINCTION CURVES. VI. THE NEAR-IR EXTINCTION LAW

    International Nuclear Information System (INIS)

    Fitzpatrick, E. L.; Massa, D.

    2009-01-01

    We combine new observations from the Hubble Space Telescope's Advanced Camera of Survey with existing data to investigate the wavelength dependence of near-IR (NIR) extinction. Previous studies suggest a power law form for NIR extinction, with a 'universal' value of the exponent, although some recent observations indicate that significant sight line-to-sight line variability may exist. We show that a power-law model for the NIR extinction provides an excellent fit to most extinction curves, but that the value of the power, β, varies significantly from sight line to sight line. Therefore, it seems that a 'universal NIR extinction law' is not possible. Instead, we find that as β decreases, R(V) ≡ A(V)/E(B - V) tends to increase, suggesting that NIR extinction curves which have been considered 'peculiar' may, in fact, be typical for different R(V) values. We show that the power-law parameters can depend on the wavelength interval used to derive them, with the β increasing as longer wavelengths are included. This result implies that extrapolating power-law fits to determine R(V) is unreliable. To avoid this problem, we adopt a different functional form for NIR extinction. This new form mimics a power law whose exponent increases with wavelength, has only two free parameters, can fit all of our curves over a longer wavelength baseline and to higher precision, and produces R(V) values which are consistent with independent estimates and commonly used methods for estimating R(V). Furthermore, unlike the power-law model, it gives R(V)s that are independent of the wavelength interval used to derive them. It also suggests that the relation R(V) = -1.36 E(K-V)/(E(B-V)) - 0.79 can estimate R(V) to ±0.12. Finally, we use model extinction curves to show that our extinction curves are in accord with theoretical expectations, and demonstrate how large samples of observational quantities can provide useful constraints on the grain properties.

  9. Extinction of Chained Instrumental Behaviors: Effects of Procurement Extinction on Consumption Responding

    Science.gov (United States)

    Thrailkill, Eric A.; Bouton, Mark E.

    2015-01-01

    Instrumental behavior often consists of sequences or chains of responses that minimally include procurement behaviors that enable subsequent consumption behaviors. In such chains, behavioral units are linked by access to one another and eventually to a primary reinforcer, such as food or a drug. The present experiments examined the effects of extinguishing procurement responding on consumption responding after training of a discriminated heterogeneous instrumental chain. Rats learned to make a procurement response (e.g., pressing a lever) in the presence of a distinctive discriminative stimulus; making that response led to the presentation of a second discriminative stimulus that set the occasion for a consumption response (e.g., pulling a chain), which then produced a food-pellet reinforcer. Experiment 1 showed that extinction of either the full procurement-consumption chain or procurement alone weakened the consumption response tested in isolation. Experiment 2 replicated the procurement extinction effect and further demonstrated that the opportunity to make the procurement response, as opposed to simple exposure to the procurement stimulus alone, was required. In Experiment 3, rats learned 2 distinct discriminated heterogeneous chains; extinction of 1 procurement response specifically weakened the consumption response that had been associated with it. The results suggest that learning to inhibit the procurement response may produce extinction of consumption responding through mediated extinction. The experiments suggest the importance of an associative analysis of instrumental behavior chains. PMID:25915751

  10. Molecular Mechanisms of Chromium in Alleviating Insulin Resistance

    Science.gov (United States)

    Hua, Yinan; Clark, Suzanne; Ren, Jun; Sreejayan, Nair

    2011-01-01

    Type 2 diabetes is often associated with obesity, dyslipidemia, and cardiovascular anomalies and is a major health problem approaching global epidemic proportions. Insulin resistance, a prediabetic condition, precedes the onset of frank type 2 diabetes and offers potential avenues for early intervention to treat the disease. Although lifestyle modifications and exercise can reduce the incidence of diabetes, compliance has proved to be difficult, warranting pharmacological interventions. However, most of the currently available drugs that improve insulin sensitivity have adverse effects. Therefore, attractive strategies to alleviate insulin resistance include dietary supplements. One such supplement is chromium, which has been shown reduce insulin resistance in some, but not all, studies. Furthermore, the molecular mechanisms of chromium in alleviating insulin resistance remain elusive. This review examines emerging reports on the effect of chromium, as well as molecular and cellular mechanisms by which chromium may provide beneficial effects in alleviating insulin resistance. PMID:22423897

  11. Strategic plant choices can alleviate climate change impacts: A review.

    Science.gov (United States)

    Espeland, Erin K; Kettenring, Karin M

    2018-06-01

    Ecosystem-based adaptation (EbA) uses biodiversity and ecosystem services to reduce climate change impacts to local communities. Because plants can alleviate the abiotic and biotic stresses of climate change, purposeful plant choices could improve adaptation. However, there has been no systematic review of how plants can be applied to alleviate effects of climate change. Here we describe how plants can modify climate change effects by altering biological and physical processes. Plant effects range from increasing soil stabilization to reducing the impact of flooding and storm surges. Given the global scale of plant-related activities such as farming, landscaping, forestry, conservation, and restoration, plants can be selected strategically-i.e., planting and maintaining particular species with desired impacts-to simultaneously restore degraded ecosystems, conserve ecosystem function, and help alleviate effects of climate change. Plants are a tool for EbA that should be more broadly and strategically utilized. Copyright © 2018. Published by Elsevier Ltd.

  12. Study of Driving Fatigue Alleviation by Transcutaneous Acupoints Electrical Stimulations

    Directory of Open Access Journals (Sweden)

    Fuwang Wang

    2014-01-01

    Full Text Available Driving fatigue is more likely to bring serious safety trouble to traffic. Therefore, accurately and rapidly detecting driving fatigue state and alleviating fatigue are particularly important. In the present work, the electrical stimulation method stimulating the Láogóng point (劳宫PC8 of human body is proposed, which is used to alleviate the mental fatigue of drivers. The wavelet packet decomposition (WPD is used to extract θ, α, and β subbands of drivers’ electroencephalogram (EEG signals. Performances of the two algorithms (θ+α/(α+β and θ/β are also assessed as possible indicators for fatigue detection. Finally, the differences between the drivers with electrical stimulation and normal driving are discussed. It is shown that stimulating the Láogóng point (劳宫PC8 using electrical stimulation method can alleviate driver fatigue effectively during longtime driving.

  13. Alleviating hidden hunger. Approaches that work

    International Nuclear Information System (INIS)

    Kennedy, E.; Mannar, V.; Iyengar, V.

    2003-01-01

    measuring the effectiveness of nutrition supplementation or fortification trials; isotope dilution methods used in the assessment of vitamin A status tracing through carbon-13 ( 13 C) carotenoids. Further, specialized applications - namely neutron activation analysis and inductively coupled plasma mass spectrometry - permit simultaneous analysis of a range of minor and trace elements in foods and beverages

  14. Consolidation of an extinction memory depends on the unconditioned stimulus magnitude previously experienced during training.

    Science.gov (United States)

    Stollhoff, Nicola; Eisenhardt, Dorothea

    2009-07-29

    Here, we examine the role of the magnitude of the unconditioned stimulus (US) during classical conditioning in consolidation processes after memory retrieval. We varied the US durations during training and we test the impact of these variations on consolidation after memory retrieval with one or two conditioned stimulus-only trials. We found that the consolidation of an extinction memory depends on US duration during training and ruled out the possibility that this effect is attributable to differences in satiation after conditioning. We conclude that consolidation of an extinction memory is triggered only when the duration of the US reaches a critical threshold. This demonstrates that memory consolidation cannot be regarded as an isolated process depending solely on training conditions. Instead, it depends on the animal's previous experience as well.

  15. Chronic psychosocial stress causes delayed extinction and exacerbates reinstatement of ethanol-induced conditioned place preference in mice.

    Science.gov (United States)

    Bahi, Amine; Dreyer, Jean-Luc

    2014-01-01

    We have shown previously, using an animal model of voluntary ethanol intake and ethanol-conditioned place preference (EtOH-CPP), that exposure to chronic psychosocial stress induces increased ethanol intake and EtOH-CPP acquisition in mice. Here, we examined the impact of chronic subordinate colony (CSC) exposure on EtOH-CPP extinction, as well as ethanol-induced reinstatement of CPP. Mice were conditioned with saline or 1.5 g/kg ethanol and were tested in the EtOH-CPP model. In the first experiment, the mice were subjected to 19 days of chronic stress, and EtOH-CPP extinction was assessed during seven daily trials without ethanol injection. In the second experiment and after the EtOH-CPP test, the mice were subjected to 7 days of extinction trials before the 19 days of chronic stress. Drug-induced EtOH-CPP reinstatement was induced by a priming injection of 0.5 g/kg ethanol. Compared to the single-housed colony mice, CSC mice exhibited increased anxiety-like behavior in the elevated plus maze (EPM) and the open field tests. Interestingly, the CSC mice showed delayed EtOH-CPP extinction. More importantly, CSC mice showed increased alcohol-induced reinstatement of the EtOH-CPP behavior. Taken together, this study indicates that chronic psychosocial stress can have long-term effects on EtOH-CPP extinction as well as drug-induced reinstatement behavior and may provide a suitable model to study the latent effects of chronic psychosocial stress on extinction and relapse to drug abuse.

  16. One extinct turtle species less: Pelusios seychellensis is not extinct, it never existed.

    Directory of Open Access Journals (Sweden)

    Heiko Stuckas

    Full Text Available Pelusios seychellensis is thought to be a freshwater turtle species endemic to the island of Mahé, Seychelles. There are only three museum specimens from the late 19(th century known. The species has been never found again, despite intensive searches on Mahé. Therefore, P. seychellensis has been declared as "Extinct" by the IUCN and is the sole putatively extinct freshwater turtle species. Using DNA sequences of three mitochondrial genes of the historical type specimen and phylogenetic analyses including all other species of the genus, we provide evidence that the description of P. seychellensis was erroneously based on a widely distributed West African species, P. castaneus. Consequently, we synonymize the two species and delete P. seychellensis from the list of extinct chelonian species and from the faunal list of the Seychelles.

  17. A window of vulnerability: impaired fear extinction in adolescence.

    Science.gov (United States)

    Baker, Kathryn D; Den, Miriam L; Graham, Bronwyn M; Richardson, Rick

    2014-09-01

    There have been significant advances made towards understanding the processes mediating extinction of learned fear. However, despite being of clear theoretical and clinical significance, very few studies have examined fear extinction in adolescence, which is often described as a developmental window of vulnerability to psychological disorders. This paper reviews the relatively small body of research examining fear extinction in adolescence. A prominent finding of this work is that adolescents, both humans and rodents, exhibit a marked impairment in extinction relative to both younger (e.g., juvenile) and older (e.g., adult) groups. We then review some potential mechanisms that could produce the striking extinction deficit observed in adolescence. For example, one neurobiological candidate mechanism for impaired extinction in adolescence involves changes in the functional connectivity within the fear extinction circuit, particularly between prefrontal cortical regions and the amygdala. In addition, we review research on emotion regulation and attention processes that suggests that developmental changes in attention bias to threatening cues may be a cognitive mechanism that mediates age-related differences in extinction learning. We also examine how a differential reaction to chronic stress in adolescence impacts upon extinction retention during adolescence as well as in later life. Finally, we consider the findings of several studies illustrating promising approaches that overcome the typically-observed extinction impairments in adolescent rodents and that could be translated to human adolescents. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Cortisol modifies extinction learning of recently acquired fear in men

    Science.gov (United States)

    Hermann, Andrea; Stark, Rudolf; Wolf, Oliver Tobias

    2014-01-01

    Exposure therapy builds on the mechanism of fear extinction leading to decreased fear responses. How the stress hormone cortisol affects brain regions involved in fear extinction in humans is unknown. For this reason, we tested 32 men randomly assigned to receive either 30 mg hydrocortisone or placebo 45 min before fear extinction. In fear acquisition, a picture of a geometrical figure was either partially paired (conditioned stimulus; CS+) or not paired (CS−) with an electrical stimulation (unconditioned stimulus; UCS). In fear extinction, each CS was presented again, but no UCS occurred. Cortisol increased conditioned skin conductance responses in early and late extinction. In early extinction, higher activation towards the CS− than to the CS+ was found in the amygdala, hippocampus and posterior parahippocampal gyrus. This pattern might be associated with the establishment of a new memory trace. In late extinction, the placebo compared with the cortisol group displayed enhanced CS+/CS− differentiation in the amygdala, medial frontal cortex and nucleus accumbens. A change from early deactivation to late activation of the extinction circuit as seen in the placebo group seems to be needed to enhance extinction and to reduce fear. Cortisol appears to interfere with this process thereby impairing extinction of recently acquired conditioned fear. PMID:23945999

  19. Augmentation of Fear Extinction by Transcranial Direct Current Stimulation (tDCS

    Directory of Open Access Journals (Sweden)

    Natalie Dittert

    2018-04-01

    Full Text Available Although posttraumatic stress disorder (PTSD; DSM-V 309.82 and anxiety disorders (DSM-V 300.xx are widely spread mental disorders, the effectiveness of their therapy is still unsatisfying. Non-invasive brain-stimulation techniques like transcranial direct current stimulation (tDCS might be an option to improve extinction learning, which is a main functional factor of exposure-based therapy for anxiety disorders. To examine this hypothesis, we used a fear conditioning paradigm with female faces as conditioned stimuli (CS and a 95-dB female scream as unconditioned stimulus (UCS. We aimed to perform a tDCS of the ventromedial prefrontal cortex (vmPFC, which is mainly involved in the control of extinction-processes. Therefore, we applied two 4 × 4 cm electrodes approximately at the EEG-positions F7 and F8 and used a direct current of 1.5 mA. The 20-min stimulation was started during a 10-min break between acquisition and extinction and went on overall extinction-trials. The healthy participants were randomly assigned in two double-blinded process into two sham stimulation and two verum stimulation groups with opposite current flow directions. To measure the fear reactions, we used skin conductance responses (SCR and subjective ratings. We performed a generalized estimating equations model for the SCR to assess the impact of tDCS and current flow direction on extinction processes for all subjects that showed a successful conditioning (N = 84. The results indicate that tDCS accelerates early extinction processes with a significantly faster loss of CS+/CS– discrimination. The discrimination loss was driven by a significant decrease in reaction toward the CS+ as well as an increase in reaction toward the CS– in the tDCS verum groups, whereas the sham groups showed no significant reaction changes during this period. Therefore, we assume that tDCS of the vmPFC can be used to enhance early extinction processes successfully. But before it should be

  20. Candesartan ameliorates impaired fear extinction induced by innate immune activation.

    Science.gov (United States)

    Quiñones, María M; Maldonado, Lizette; Velazquez, Bethzaly; Porter, James T

    2016-02-01

    Patients with post-traumatic stress disorder (PTSD) tend to show signs of a relatively increased inflammatory state suggesting that activation of the immune system may contribute to the development of PTSD. In the present study, we tested whether activation of the innate immune system can disrupt acquisition or recall of auditory fear extinction using an animal model of PTSD. Male adolescent rats received auditory fear conditioning in context A. The next day, an intraperitoneal injection of lipopolysaccharide (LPS; 100 μg/kg) prior to auditory fear extinction in context B impaired acquisition and recall of extinction. LPS (100 μg/kg) given after extinction training did not impair extinction recall suggesting that LPS did not affect consolidation of extinction. In contrast to cued fear extinction, contextual fear extinction was not affected by prior injection of LPS (100 μg/kg). Although LPS also reduced locomotion, we could dissociate the effects of LPS on extinction and locomotion by using a lower dose of LPS (50 μg/kg) which impaired locomotion without affecting extinction. In addition, 15 h after an injection of 250 μg/kg LPS in adult rats, extinction learning and recall were impaired without affecting locomotion. A sub-chronic treatment with candesartan, an angiotensin II type 1 receptor blocker, prevented the LPS-induced impairment of extinction in adult rats. Our results demonstrate that activation of the innate immune system can disrupt auditory fear extinction in adolescent and adult animals. These findings also provide direction for clinical studies of novel treatments that modulate the innate immune system for stress-related disorders like PTSD. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Acute infusion of brain-derived neurotrophic factor in the insular cortex promotes conditioned taste aversion extinction.

    Science.gov (United States)

    Rodríguez-Serrano, Luis M; Ramírez-León, Betsabee; Rodríguez-Durán, Luis F; Escobar, Martha L

    2014-12-01

    Brain-derived neurotrophic factor (BDNF) has emerged as one of the most potent molecular mediators not only for synaptic plasticity, but also for the behavioral organism-environment interactions. Our previous studies in the insular cortex (IC), a neocortical region that has been related with acquisition and retention of conditioned taste aversion (CTA), have demonstrated that intracortical microinfusion of BDNF induces a lasting potentiation of synaptic efficacy in the basolateral amygdaloid nucleus (Bla)-IC projection and enhances the retention of CTA memory of adult rats in vivo. The aim of the present study was to analyze whether acute BDNF-infusion in the IC modifies the extinction of CTA. Accordingly, animals were trained in the CTA task and received bilateral IC microinfusions of BDNF before extinction training. Our results showed that taste aversion was significantly reduced in BDNF rats from the first extinction trial. Additionally, we found that the effect of BDNF on taste aversion did not require extinction training. Finally we showed that the BDNF effect does not degrade the original taste aversion memory trace. These results emphasize that BDNF activity underlies memory extinction in neocortical areas and support the idea that BDNF is a key regulator and mediator of long-term synaptic modifications. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Mass extinction efficiency and extinction hygroscopicity of ambient PM2.5 in urban China.

    Science.gov (United States)

    Cheng, Zhen; Ma, Xin; He, Yujie; Jiang, Jingkun; Wang, Xiaoliang; Wang, Yungang; Sheng, Li; Hu, Jiangkai; Yan, Naiqiang

    2017-07-01

    The ambient PM 2.5 pollution problem in China has drawn substantial international attentions. The mass extinction efficiency (MEE) and hygroscopicity factor (f(RH)) of PM 2.5 can be readily applied to study the impacts on atmospheric visibility and climate. The few previous investigations in China only reported results from pilot studies and are lack of spatial representativeness. In this study, hourly average ambient PM 2.5 mass concentration, relative humidity, and atmospheric visibility data from China national air quality and meteorological monitoring networks were retrieved and analyzed. It includes 24 major Chinese cities from nine city-clusters with the period of October 2013 to September 2014. Annual average extinction coefficient in urban China was 759.3±258.3Mm -1 , mainly caused by dry PM 2.5 (305.8.2±131.0Mm -1 ) and its hygroscopicity (414.6±188.1Mm -1 ). High extinction coefficient values were resulted from both high ambient PM 2.5 concentration (68.5±21.7µg/m 3 ) and high relative humidity (69.7±8.6%). The PM 2.5 mass extinction efficiency varied from 2.87 to 6.64m 2 /g with an average of 4.40±0.84m 2 /g. The average extinction hygroscopic factor f(RH=80%) was 2.63±0.45. The levels of PM 2.5 mass extinction efficiency and hygroscopic factor in China were in comparable range with those found in developed countries in spite of the significant diversities among all 24 cities. Our findings help to establish quantitative relationship between ambient extinction coefficient (visual range) and PM 2.5 & relative humidity. It will reduce the uncertainty of extinction coefficient estimation of ambient PM 2.5 in urban China which is essential for the research of haze pollution and climate radiative forcing. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. PDE5 inhibition alleviates functional muscle ischemia in boys with Duchenne muscular dystrophy.

    Science.gov (United States)

    Nelson, Michael D; Rader, Florian; Tang, Xiu; Tavyev, Jane; Nelson, Stanley F; Miceli, M Carrie; Elashoff, Robert M; Sweeney, H Lee; Victor, Ronald G

    2014-06-10

    To determine whether phosphodiesterase type 5 (PDE5) inhibition can alleviate exercise-induced skeletal muscle ischemia in boys with Duchenne muscular dystrophy (DMD). In 10 boys with DMD and 10 healthy age-matched male controls, we assessed exercise-induced attenuation of reflex sympathetic vasoconstriction, i.e., functional sympatholysis, a protective mechanism that matches oxygen delivery to metabolic demand. Reflex vasoconstriction was induced by simulated orthostatic stress, measured as the decrease in forearm muscle oxygenation with near-infrared spectroscopy, and performed when the forearm muscles were rested or lightly exercised with rhythmic handgrip exercise. Then, the patients underwent an open-label, dose-escalation, crossover trial with single oral doses of tadalafil or sildenafil. The major new findings are 2-fold: first, sympatholysis is impaired in boys with DMD-producing functional muscle ischemia-despite contemporary background therapy with corticosteroids alone or in combination with cardioprotective medication. Second, PDE5 inhibition with standard clinical doses of either tadalafil or sildenafil alleviates this ischemia in a dose-dependent manner. Furthermore, PDE5 inhibition also normalizes the exercise-induced increase in skeletal muscle blood flow (measured by Doppler ultrasound), which is markedly blunted in boys with DMD. These data provide in-human proof of concept for PDE5 inhibition as a putative new therapeutic strategy for DMD. This study provides Class IV evidence that in patients with DMD, PDE5 inhibition restores functional sympatholysis. © 2014 American Academy of Neurology.

  4. Ebselen alleviates testicular pathology in mice with Zika virus infection and prevents its sexual transmission.

    Science.gov (United States)

    Simanjuntak, Yogy; Liang, Jian-Jong; Chen, Si-Yu; Li, Jin-Kun; Lee, Yi-Ling; Wu, Han-Chung; Lin, Yi-Ling

    2018-02-01

    Despite the low case fatality, Zika virus (ZIKV) infection has been associated with microcephaly in infants and Guillain-Barré syndrome. Antiviral and vaccine developments against ZIKV are still ongoing; therefore, in the meantime, preventing the disease transmission is critical. Primarily transmitted by Aedes species mosquitoes, ZIKV also can be sexually transmitted. We used AG129 mice lacking interferon-α/β and -γ receptors to study the testicular pathogenesis and sexual transmission of ZIKV. Infection of ZIKV progressively damaged mouse testes, increased testicular oxidative stress as indicated by the levels of reactive oxygen species, nitric oxide, glutathione peroxidase 4, spermatogenesis-associated-18 homolog in sperm and pro-inflammatory cytokines including IL-1β, IL-6, and G-CSF. We then evaluated the potential role of the antioxidant ebselen (EBS) in alleviating the testicular pathology with ZIKV infection. EBS treatment significantly reduced ZIKV-induced testicular oxidative stress, leucocyte infiltration and production of pro-inflammatory response. Furthermore, it improved testicular pathology and prevented the sexual transmission of ZIKV in a male-to-female mouse sperm transfer model. EBS is currently in clinical trials for various diseases. ZIKV infection could be on the list for potential use of EBS, for alleviating the testicular pathogenesis with ZIKV infection and preventing its sexual transmission.

  5. Ebselen alleviates testicular pathology in mice with Zika virus infection and prevents its sexual transmission.

    Directory of Open Access Journals (Sweden)

    Yogy Simanjuntak

    2018-02-01

    Full Text Available Despite the low case fatality, Zika virus (ZIKV infection has been associated with microcephaly in infants and Guillain-Barré syndrome. Antiviral and vaccine developments against ZIKV are still ongoing; therefore, in the meantime, preventing the disease transmission is critical. Primarily transmitted by Aedes species mosquitoes, ZIKV also can be sexually transmitted. We used AG129 mice lacking interferon-α/β and -γ receptors to study the testicular pathogenesis and sexual transmission of ZIKV. Infection of ZIKV progressively damaged mouse testes, increased testicular oxidative stress as indicated by the levels of reactive oxygen species, nitric oxide, glutathione peroxidase 4, spermatogenesis-associated-18 homolog in sperm and pro-inflammatory cytokines including IL-1β, IL-6, and G-CSF. We then evaluated the potential role of the antioxidant ebselen (EBS in alleviating the testicular pathology with ZIKV infection. EBS treatment significantly reduced ZIKV-induced testicular oxidative stress, leucocyte infiltration and production of pro-inflammatory response. Furthermore, it improved testicular pathology and prevented the sexual transmission of ZIKV in a male-to-female mouse sperm transfer model. EBS is currently in clinical trials for various diseases. ZIKV infection could be on the list for potential use of EBS, for alleviating the testicular pathogenesis with ZIKV infection and preventing its sexual transmission.

  6. Social Stories™ to alleviate challenging behaviour and social difficulties exhibited by children with autism spectrum disorder in mainstream schools: design of a manualised training toolkit and feasibility study for a cluster randomised controlled trial with nested qualitative and cost-effectiveness components.

    Science.gov (United States)

    Wright, Barry; Marshall, David; Adamson, Joy; Ainsworth, Hannah; Ali, Shehzad; Allgar, Victoria; Collingridge Moore, Danielle; Cook, Elizabeth; Dempster, Paul; Hackney, Lisa; McMillan, Dean; Trepél, Dominic; Williams, Chris

    2016-01-01

    A Social Story™ (Carol Gray) is a child-friendly intervention that is used to give children with autism spectrum disorders (ASDs) social information in situations where they have social difficulties. Limited evidence mainly using single-case designs suggests that they can reduce anxiety and challenging behaviour. The objectives were to conduct a systematic review, use this to develop a manualised intervention and run a feasibility trial to inform a fully powered randomised controlled trial (RCT) on their clinical effectiveness and cost-effectiveness in schools. This is a three-stage study following the Medical Research Council framework for complex interventions. Specifically, it involved a theoretical phase, a qualitative stage and a feasibility trial stage. Qualitative interviews and focus groups took place in Child and Adolescent Mental Health Service and primary care settings. The feasibility study took place in 37 local mainstream schools. Fifty children (aged 5-15 years) in mainstream school settings with a diagnosis of ASD were entered into the trial. For each child, an associated teacher and parent was also recruited. The intervention was a goal-setting session followed by a manualised toolkit (including a training session) for creating Social Stories™ for use with school-aged children. The comparator treatment was a goal-setting session followed by an attention control. Both arms received treatment as usual. Outcomes tested as part of the feasibility study included child- and proxy-completed questionnaires for mental health, quality of life and goal-based outcome measures. Adults additionally completed behaviour diaries and the parental stress index. The review found that the research into social stories is predominantly based in the USA, carried out in under-12-year-olds and using single-case designs. Most studies either did not follow established Social Story criteria or did not report if they did. The assessment of effectiveness presents a largely

  7. Ganokendra: An Innovative Model for Poverty Alleviation in Bangladesh

    Science.gov (United States)

    Alam, Kazi Rafiqul

    2006-01-01

    Ganokendras (people's learning centers) employ a literacy-based approach to alleviating poverty in Bangladesh. They give special attention to empowering rural women, among whom poverty is widespread. The present study reviews the Ganokendra-approach to facilitating increased political and economic awareness and improving community conditions in…

  8. 283 Poverty Alleviation Programmes and Economic Development in ...

    African Journals Online (AJOL)

    Nekky Umera

    poverty alleviation on the inhabitants of Nigeria with special reference to. Asa and Ilorin West Local ... poverty is defined as a state of deprivation in terms of both economic and social indicators such as income ..... Source Book. The World Bank ...

  9. Role of Zakah and Awqaf in poverty Alleviation (Occasional Paper)

    OpenAIRE

    Ahmed, Habib

    2004-01-01

    The occasional paper studies the role of zakat and awqaf in mitigating poverty in Muslim communities. The study addresses the issue by studying the institutional set-up and mechanisms of using zakat and awqaf for poverty alleviation. It discusses how these institutions can be implemented successfully to achieve the results in contemporary times using theoretical arguments and empirical support.

  10. Youth Empowerment and Poverty Alleviation: The Experience in ...

    African Journals Online (AJOL)

    It will help the planners and the policy makers to determine the best methods to tackle poverty in order to alleviate youth employment. The study made use of descriptive research design for the investigation. All the local government in Ogun State constitutes the population for the study. Out of these, two local governments ...

  11. Urban agriculture and urban poverty alleviation: South African debates

    OpenAIRE

    Rogerson, Christian M.

    1998-01-01

    Growing international attention has focussed on the potential role of urban agriculture in poverty alleviation. The aim in this paper is to analyse the existing challenge of urban poverty in South Africa and examine the potential role of urban agriculture as a component of a pro-poor urban development strategy.

  12. Alleviating poverty and hunger in Nigeria: Lessons from the United ...

    African Journals Online (AJOL)

    Nigeria is facing serious poverty and hunger despite her enormous resources. Recent statistics reveal that poverty and hunger are increasing despite successive governments and non–governmental organizations alleviation programmes. Unless, these twin problems are tacked urgently, they are likely to undermine the ...

  13. Resilience offers escape from trapped thinking on poverty alleviation.

    Science.gov (United States)

    Lade, Steven J; Haider, L Jamila; Engström, Gustav; Schlüter, Maja

    2017-05-01

    The poverty trap concept strongly influences current research and policy on poverty alleviation. Financial or technological inputs intended to "push" the rural poor out of a poverty trap have had many successes but have also failed unexpectedly with serious ecological and social consequences that can reinforce poverty. Resilience thinking can help to (i) understand how these failures emerge from the complex relationships between humans and the ecosystems on which they depend and (ii) navigate diverse poverty alleviation strategies, such as transformative change, that may instead be required. First, we review commonly observed or assumed social-ecological relationships in rural development contexts, focusing on economic, biophysical, and cultural aspects of poverty. Second, we develop a classification of poverty alleviation strategies using insights from resilience research on social-ecological change. Last, we use these advances to develop stylized, multidimensional poverty trap models. The models show that (i) interventions that ignore nature and culture can reinforce poverty (particularly in agrobiodiverse landscapes), (ii) transformative change can instead open new pathways for poverty alleviation, and (iii) asset inputs may be effective in other contexts (for example, where resource degradation and poverty are tightly interlinked). Our model-based approach and insights offer a systematic way to review the consequences of the causal mechanisms that characterize poverty traps in different agricultural contexts and identify appropriate strategies for rural development challenges.

  14. Contribution of food security projects on poverty alleviation to the ...

    African Journals Online (AJOL)

    Despite South Africa's economic growth having been accelerated considerably in the country, poverty levels have not decreased as one would have experienced. Food Security Projects initiated by the government of South Africa in order to help alleviate poverty within Limpopo Province have proved unsustainable and ...

  15. Wealth Creation and Poverty Alleviation in Nigeria: The Role of ...

    African Journals Online (AJOL)

    The study investigated the Role of Information Technology (IT) in thecreation of wealth and poverty alleviation in Nigeria. The design of the studywas a descriptive survey, carried out at Nwafor Orizu College of Education,Nsugbe in Anambra State of Nigeria. One hundred and ninety three (193)respondents formed the ...

  16. Resilience offers escape from trapped thinking on poverty alleviation

    Science.gov (United States)

    Lade, Steven J.; Haider, L. Jamila; Engström, Gustav; Schlüter, Maja

    2017-01-01

    The poverty trap concept strongly influences current research and policy on poverty alleviation. Financial or technological inputs intended to “push” the rural poor out of a poverty trap have had many successes but have also failed unexpectedly with serious ecological and social consequences that can reinforce poverty. Resilience thinking can help to (i) understand how these failures emerge from the complex relationships between humans and the ecosystems on which they depend and (ii) navigate diverse poverty alleviation strategies, such as transformative change, that may instead be required. First, we review commonly observed or assumed social-ecological relationships in rural development contexts, focusing on economic, biophysical, and cultural aspects of poverty. Second, we develop a classification of poverty alleviation strategies using insights from resilience research on social-ecological change. Last, we use these advances to develop stylized, multidimensional poverty trap models. The models show that (i) interventions that ignore nature and culture can reinforce poverty (particularly in agrobiodiverse landscapes), (ii) transformative change can instead open new pathways for poverty alleviation, and (iii) asset inputs may be effective in other contexts (for example, where resource degradation and poverty are tightly interlinked). Our model-based approach and insights offer a systematic way to review the consequences of the causal mechanisms that characterize poverty traps in different agricultural contexts and identify appropriate strategies for rural development challenges. PMID:28508077

  17. Enabling Bio-Innovation for Poverty Alleviation in Asia | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    At first glance, Asia seems to have all the organizations, skills, policies and facilities essential for bio-innovation. However, these are not generally put to the service of the millions of poor who lack access to technology. This project aims to stimulate research on bio-innovation for poverty alleviation, sustainable employment ...

  18. Poverty alleviation with economic growth strategy: Prospects and ...

    African Journals Online (AJOL)

    The prospects and challenges of this strategy in the context of the Nigerian situation are articulated and the conclusion of the paper is that poverty alleviation in contemporary Nigeria requires both economic policy and educational reforms. To enhance the human capital of the poor in particular, the priorities for educational ...

  19. Causes and Alleviation of Occupational Stress in Child Care Work

    Science.gov (United States)

    Dillenburger, Karola

    2004-01-01

    Occupational stress in not a new phenomenon in the working population. However, in the helping professions it has only recently attracted attention. The survey reported here was carried out in order to assess the extent of occupational stress, identify its causes, and suggest ways in which occupational stress can be alleviated. Field social…

  20. Ecological selectivity of the emerging mass extinction in the oceans.

    Science.gov (United States)

    Payne, Jonathan L; Bush, Andrew M; Heim, Noel A; Knope, Matthew L; McCauley, Douglas J

    2016-09-16

    To better predict the ecological and evolutionary effects of the emerging biodiversity crisis in the modern oceans, we compared the association between extinction threat and ecological traits in modern marine animals to associations observed during past extinction events using a database of 2497 marine vertebrate and mollusc genera. We find that extinction threat in the modern oceans is strongly associated with large body size, whereas past extinction events were either nonselective or preferentially removed smaller-bodied taxa. Pelagic animals were victimized more than benthic animals during previous mass extinctions but are not preferentially threatened in the modern ocean. The differential importance of large-bodied animals to ecosystem function portends greater future ecological disruption than that caused by similar levels of taxonomic loss in past mass extinction events. Copyright © 2016, American Association for the Advancement of Science.

  1. Aging accelerates memory extinction and impairs memory restoration in Drosophila.

    Science.gov (United States)

    Chen, Nannan; Guo, Aike; Li, Yan

    2015-05-15

    Age-related memory impairment (AMI) is a phenomenon observed from invertebrates to human. Memory extinction is proposed to be an active inhibitory modification of memory, however, whether extinction is affected in aging animals remains to be elucidated. Employing a modified paradigm for studying memory extinction in fruit flies, we found that only the stable, but not the labile memory component was suppressed by extinction, thus effectively resulting in higher memory loss in aging flies. Strikingly, young flies were able to fully restore the stable memory component 3 h post extinction, while aging flies failed to do so. In conclusion, our findings reveal that both accelerated extinction and impaired restoration contribute to memory impairment in aging animals. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Reintroducing resurrected species: selecting DeExtinction candidates.

    Science.gov (United States)

    Seddon, Philip J; Moehrenschlager, Axel; Ewen, John

    2014-03-01

    Technological advances have raised the controversial prospect of resurrecting extinct species. Species DeExtinction should involve more than the production of biological orphans to be scrutinized in the laboratory or zoo. If DeExtinction is to realize its stated goals of deep ecological enrichment, then resurrected animals must be translocated (i.e., released within suitable habitat). Therefore, DeExtinction is a conservation translocation issue and the selection of potential DeExtinction candidates must consider the feasibility and risks associated with reintroduction. The International Union for the Conservation of Nature (IUCN) Guidelines on Reintroductions and Other Conservation Translocations provide a framework for DeExtinction candidate selection. We translate these Guidelines into ten questions to be addressed early on in the selection process to eliminate unsuitable reintroduction candidates. We apply these questions to the thylacine, Yangtze River Dolphin, and Xerces blue butterfly. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Noradrenergic Modulation of Fear Conditioning and Extinction.

    Science.gov (United States)

    Giustino, Thomas F; Maren, Stephen

    2018-01-01

    The locus coeruleus norepinephrine (LC-NE) system plays a broad role in learning and memory. Here we begin with an overview of the LC-NE system. We then consider how both direct and indirect manipulations of the LC-NE system affect cued and contextual aversive learning and memory. We propose that NE dynamically modulates Pavlovian conditioning and extinction, either promoting or impairing learning aversive processes under different levels of behavioral arousal. We suggest that under high levels of stress (e.g., during/soon after fear conditioning) the locus coeruleus (LC) promotes cued fear learning by enhancing amygdala function while simultaneously blunting prefrontal function. Under low levels of arousal, the LC promotes PFC function to promote downstream inhibition of the amygdala and foster the extinction of cued fear. Thus, LC-NE action on the medial prefrontal cortex (mPFC) might be described by an inverted-U function such that it can either enhance or hinder learning depending on arousal states. In addition, LC-NE seems to be particularly important for the acquisition, consolidation and extinction of contextual fear memories. This may be due to dense adrenoceptor expression in the hippocampus (HPC) which encodes contextual information, and the ability of NE to regulate long-term potentiation (LTP). Moreover, recent work reveals that the diversity of LC-NE functions in aversive learning and memory are mediated by functionally heterogeneous populations of LC neurons that are defined by their projection targets. Hence, LC-NE function in learning and memory is determined by projection-specific neuromodulation that accompanies various states of behavioral arousal.

  4. Late Pennsylvanian climate changes and palynomorph extinctions

    Energy Technology Data Exchange (ETDEWEB)

    Kosanke, R.M.; Cecil, C.B. [US Geological Survey, Denver, CO (United States)

    1996-01-01

    A major floral change occurs in the Upper Pennsylvanian strata in the Midcontinent, Illinois basin, and in the northern Appalachian basin of eastern United States. Lycospora spp. (derived from arborescent lycopsids) became extinct along with some other palynomorph taxa. This investigation is concerned with the importance of this major floral change. Samples were studied from western Pennsylvania, eastern Ohio, and West Virgina (from a previous study) cover the stratigraphic interval from the Upper Freeport coal bed, uppermost part of the Allegheny Formation, to the Mahoning, Mason, Brush Creek, Wilgus, and Anderson coal beds in the lower part of the Conemaugh Formation. The floral change occurs either at or below the accepted Desmoinesian-Missourian boundary in the Midcontinent and Illinois basin, whereas in the northern Appalachians this change occurs in the lower part of the Conemaugh Formation, between the Mahoning and Brush Creek coal beds, or when the Mason is present, between the Mahoning and Mason coal beds. The first coal bed above the extinction of Lycospora spp. is dominated by the palynomorph taxon Endosporites globiformis which is derived from a heterosporous, herbaceous lycopsid. However, Sigillaria, another arborescent lycopsid, did not become extinct at this time as evidenced by the presence of the palynomorph genus Crassispora which is derived from Sigillaria. The reason for the survival of Sigillaria is now known, but it may have been able to adapt, in a limited fashion, to some sort of specialized microenvironment. The ferns, based on palynomorph occurrence, become numerically more important throughout the balance of the Conemaugh Formation, and dominate the Pittsburgh No. 8 and Pomeroy coal beds in the overlying Monogahela Formation.

  5. Fire extinction utilizing carbon dioxide hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Hatakeyama, T.; Aida, E.; Yokomori, T.; Ohmura, R.; Ueda, T. [Keio Univ., Hiyoshi, Kohoku-ku, Yokohama (Japan)

    2008-07-01

    Clathrate hydrates formed with nonflammable gases may be suitable for use as fire extinguishing agents because dissociation of the hydrates results in the temperature decrease in the combustion field and the nonflammable gases released from the dissociated hydrates prevent the supply of the oxygen to the combustion field. This paper discussed experiments in which ordinary ice and dry ice were used to evaluate the performance of CO{sub 2} hydrate as a fire extinguishing agent. The paper described the apparatus and procedure for the preparation of CO{sub 2} hydrate crystals. A schematic of the reactor to form CO{sub 2} hydrate and a photograph of CO{sub 2} hydrate crystal formed in the study were also presented. Other illustrations, photographs, and tables that were presented included a schematic diagram of the experimental apparatus used for the flame extinction experiments; a photograph of CO{sub 2} hydrate powder; sequential video graphs of the flame extinction by the supply of CO{sub 2} hydrate crystals to the methanol pool flame and the relevant illustration; and heat of CO{sub 2} hydrate dissociation, water vaporization and sublimation of dry ice. It was concluded that the critical mass of the CO{sub 2} hydrate required to extinguish a flame was much less than that of ordinary ice, indicating the superiority of CO{sub 2} hydrate to the ice. In addition, the experiments also revealed that the size of the CO{sub 2} hydrate particles had a significant effect on the performance of flame extinction. 5 refs., 2 tabs., 7 figs.

  6. Noradrenergic Modulation of Fear Conditioning and Extinction

    Directory of Open Access Journals (Sweden)

    Thomas F. Giustino

    2018-03-01

    Full Text Available The locus coeruleus norepinephrine (LC-NE system plays a broad role in learning and memory. Here we begin with an overview of the LC-NE system. We then consider how both direct and indirect manipulations of the LC-NE system affect cued and contextual aversive learning and memory. We propose that NE dynamically modulates Pavlovian conditioning and extinction, either promoting or impairing learning aversive processes under different levels of behavioral arousal. We suggest that under high levels of stress (e.g., during/soon after fear conditioning the locus coeruleus (LC promotes cued fear learning by enhancing amygdala function while simultaneously blunting prefrontal function. Under low levels of arousal, the LC promotes PFC function to promote downstream inhibition of the amygdala and foster the extinction of cued fear. Thus, LC-NE action on the medial prefrontal cortex (mPFC might be described by an inverted-U function such that it can either enhance or hinder learning depending on arousal states. In addition, LC-NE seems to be particularly important for the acquisition, consolidation and extinction of contextual fear memories. This may be due to dense adrenoceptor expression in the hippocampus (HPC which encodes contextual information, and the ability of NE to regulate long-term potentiation (LTP. Moreover, recent work reveals that the diversity of LC-NE functions in aversive learning and memory are mediated by functionally heterogeneous populations of LC neurons that are defined by their projection targets. Hence, LC-NE function in learning and memory is determined by projection-specific neuromodulation that accompanies various states of behavioral arousal.

  7. Rho Ophiuchi Cloud Core Extinction Map

    Science.gov (United States)

    Gibson, D. J.; Rudolph, A.; Barsony, M.

    1997-12-01

    We present an extinction map of a one square degree region ( ~ 2.2pc square) of the core of the star-forming region rho Ophiuchi derived by the method of star counts. Photometry from the near-infrared J, H, and K band images of Barsony et al. (1997) provided the stellar catalog for this study. From this map an estimate of the mass of the region is made and compared with previous estimates from other methods. Reference Barsony, M., Kenyon, S.J., Lada, E.A., & Teuben, P.J. 1997, ApJS, 112, 109

  8. The risk of extinction - the mutational meltdown or the overpopulation

    OpenAIRE

    Malarz, K.

    2006-01-01

    The phase diagrams survival-extinction for the Penna model with parameters: (mutations rate)-(birth rate), (mutation rate)-(harmful mutations threshold), (harmful mutation threshold)-(minimal reproduction age) are presented. The extinction phase may be caused by either mutational meltdown or overpopulation. When the Verhulst factor is responsible for removing only newly born babies and does not act on adults the overpopulation is avoided and only genetic factors may lead to species extinction.

  9. Variation of the extinction law in the Trifid nebula

    OpenAIRE

    Cambrésy, L.; Rho, J.; Marshall, D. J.; Reach, W. T.

    2011-01-01

    Context. In the past few years, the extinction law has been measured in the infrared wavelengths for various molecular clouds and different laws have been obtained. Aims. In this paper we seek variations of the extinction law within the Trifid nebula region. Such variations would demonstrate local dust evolution linked to variation of the environment parameters such as the density or the interstellar radiation field. Methods. The extinction values, A_λ/A_v, are obtained using the 2MASS, UKIDS...

  10. Dynamics of Population on the Verge of Extinction

    OpenAIRE

    Oborny, B.; Meszena, G.; Szabo, G.

    2005-01-01

    Theoretical considerations suggest that extinction in dispersal-limited populations is necessarily a threshold-like process that is analogous to a critical phase transition in physics. We use this analogy to find robust, common features in the dynamics of extinctions, and suggest early warning signals which may indicate that a population is endangered. As the critical threshold of extinction is approached, the population spontaneously fragments into discrete subpopulations and, consequently, ...

  11. Extinction and dust properties in a clumpy medium

    OpenAIRE

    Scicluna, P.; Siebenmorgen, R.

    2015-01-01

    (abridged) The dust content of the universe is primarily explored via its interaction with stellar photons, producing interstellar extinction. However, owing to the physical extension of the observing beam, observations may detect scattered photons, resulting in a change in the observed (or effective) extinction, depending on the spatial distribution of the dust and the resolution of the instrument. We investigate the influence of clumpy dust distributions on effective extinction toward embed...

  12. Psychological and neural mechanisms of experimental extinction: a selective review.

    Science.gov (United States)

    Delamater, Andrew R; Westbrook, R Frederick

    2014-02-01

    The present review examines key psychological concepts in the study of experimental extinction and implications these have for an understanding of the underlying neurobiology of extinction learning. We suggest that many of the signature characteristics of extinction learning (spontaneous recovery, renewal, reinstatement, rapid reacquisition) can be accommodated by the standard associative learning theory assumption that extinction results in partial erasure of the original learning together with new inhibitory learning. Moreover, we consider recent behavioral and neural evidence that supports the partial erasure view of extinction, but also note shortcomings in our understanding of extinction circuits as these relate to the negative prediction error concept. Recent work suggests that common prediction error and stimulus-specific prediction error terms both may be required to explain neural plasticity both in acquisition and extinction learning. In addition, we suggest that many issues in the content of extinction learning have not been fully addressed in current research, but that neurobiological approaches should be especially helpful in addressing such issues. These include questions about the nature of extinction learning (excitatory CS-No US, inhibitory CS-US learning, occasion setting processes), especially as this relates to studies of the micro-circuitry of extinction, as well as its representational content (sensory, motivational, response). An additional understudied problem in extinction research is the role played by attention processes and their underlying neural networks, although some research and theory converge on the idea that extinction is accompanied by attention decrements (i.e., habituation-like processes). Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Unbounded autocatalytic growth on diffusive substrate: The extinction transition

    International Nuclear Information System (INIS)

    Moalem, Sasi; Shnerb, Nadav M.

    2007-01-01

    The effect of diffusively correlated spatial fluctuations on the proliferation-extinction transition of autocatalytic agents is investigated numerically. Reactants adaptation to spatio-temporal active regions is shown to lead to proliferation even if the mean field rate equations predict extinction, in agreement with previous theoretical predictions. While in the proliferation phase the system admits a typical time scale that dictates the exponential growth, the extinction times distribution obeys a power law at the parameter region considered

  14. Fear extinction requires infralimbic cortex projections to the basolateral amygdala.

    Science.gov (United States)

    Bloodgood, Daniel W; Sugam, Jonathan A; Holmes, Andrew; Kash, Thomas L

    2018-03-06

    Fear extinction involves the formation of a new memory trace that attenuates fear responses to a conditioned aversive memory, and extinction impairments are implicated in trauma- and stress-related disorders. Previous studies in rodents have found that the infralimbic prefrontal cortex (IL) and its glutamatergic projections to the basolateral amygdala (BLA) and basomedial amygdala (BMA) instruct the formation of fear extinction memories. However, it is unclear whether these pathways are exclusively involved in extinction, or whether other major targets of the IL, such as the nucleus accumbens (NAc) also play a role. To address this outstanding issue, the current study employed a combination of electrophysiological and chemogenetic approaches in mice to interrogate the role of IL-BLA and IL-NAc pathways in extinction. Specifically, we used patch-clamp electrophysiology coupled with retrograde tracing to examine changes in neuronal activity of the IL and prelimbic cortex (PL) projections to both the BLA and NAc following fear extinction. We found that extinction produced a significant increase in the intrinsic excitability of IL-BLA projection neurons, while extinction appeared to reverse fear-induced changes in IL-NAc projection neurons. To establish a causal counterpart to these observations, we then used a pathway-specific Designer Receptors Exclusively Activated by Designer Drugs (DREADD) strategy to selectively inhibit PFC-BLA projection neurons during extinction acquisition. Using this approach, we found that DREADD-mediated inhibition of PFC-BLA neurons during extinction acquisition impaired subsequent extinction retrieval. Taken together, our findings provide further evidence for a critical contribution of the IL-BLA neural circuit to fear extinction.

  15. Glutamatergic Targets for Enhancing Extinction Learning in Drug Addiction

    OpenAIRE

    Cleva, R.M; Gass, J.T; Widholm, J.J; Olive, M.F

    2010-01-01

    The persistence of the motivational salience of drug-related environmental cues and contexts is one of the most problematic obstacles to successful treatment of drug addiction. Behavioral approaches to extinguishing the salience of drug-associated cues, such as cue exposure therapy, have generally produced disappointing results which have been attributed to, among other things, the context specificity of extinction and inadequate consolidation of extinction learning. Extinction of any behavio...

  16. The risk of extinction - the mutational meltdown or the overpopulation.

    Science.gov (United States)

    Malarz, Krzysztof

    2007-04-01

    The phase diagrams survival-extinction for the Penna model with parameters: (mutations rate)-(birth rate), (mutation rate)-(harmful mutations threshold), (harmful mutation threshold)-(minimal reproduction age) are presented. The extinction phase may be caused by either mutational meltdown or overpopulation. When the Verhulst factor is responsible for removing only newly born babies and does not act on adults the overpopulation is avoided and only genetic factors may lead to species extinction.

  17. Geographies of Conservation I: De-extinction and Precision Conservation

    OpenAIRE

    Adams, William Mark

    2016-01-01

    Extinction has long been a central concern in biodiversity conservation. Today, de-extinction offers interesting possibilities of restoring charismatic species and ecosystem function, but also risks and costs. Most de-extinction depends on genetic engineering and synthetic biology. These technologies are also proposed for use in ‘gene tweaking’ in wild species to enhance their chance of survival. Within conservation, the resulting debates pit an optimistic world of high-tech ‘precision con...

  18. Precision Photometric Extinction Corrections from Direct Atmospheric Measurements

    Science.gov (United States)

    McGraw, John T.; Zimmer, P.; Linford, J.; Simon, T.; Measurement Astrophysics Research Group

    2009-01-01

    For decades astronomical extinction corrections have been accomplished using nightly mean extinction coefficients derived from Langley plots measured with the same telescope used for photometry. Because this technique results in lost time on program fields, observers only grudgingly made sporadic extinction measurements. Occasionally extinction corrections are not measured nightly but are made using tabulated mean monthly or even quarterly extinction coefficients. Any observer of the sky knows that Earth's atmosphere is an ever-changing fluid in which is embedded extinction sources ranging from Rayleigh (molecular) scattering to aerosol, smoke and dust scattering and absorption, to "just plain cloudy.” Our eyes also tell us that the type, direction and degree of extinction changes on time scales of minutes or less - typically shorter than many astronomical observations. Thus, we should expect that atmospheric extinction can change significantly during a single observation. Mean extinction coefficients might be well-defined nightly means, but those means have high variance because they do not accurately record the wavelength-, time-, and angle-dependent extinction actually affecting each observation. Our research group is implementing lidar measurements made in the direction of observation with one minute cadence, from which the absolute monochromatic extinction can be measured. Simultaneous spectrophotometry of nearby bright standard stars allows derivation and MODTRAN modeling atmospheric transmission as a function of wavelength for the atmosphere through which an observation is made. Application of this technique is demonstrated. Accurate real-time extinction measurements are an enabling factor for sub-1% photometry. This research is supported by NSF Grant 0421087 and AFRL Grant #FA9451-04-2-0355.

  19. Late Quaternary extinctions: The promise of TAMS 14C dating

    International Nuclear Information System (INIS)

    Martin, P.S.

    1987-01-01

    In the last 30 000 years late Quaternary extinctions eliminated over two-thirds of the large land mammals of America and Australia and most of the endemic land vertebrates on oceanic islands. Specimens of extinct animals yielding too little organic material for measurement in decay counters are suitable for TAMS dating. Initial results support older evidence of an extinction chronology that was catastrophic regionally, transgressive globally, and linked to the spread of prehistoric people. (orig.)

  20. Compound stimulus extinction reduces spontaneous recovery in humans

    OpenAIRE

    Coelho, Cesar A.O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.

    2015-01-01

    Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design (“deepened extinction”) shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately paired with an electric shock. The target CS (CSA) was extinguished alone followed by compound presentations of the extinguished CSA and nonextinguished CSB. Reco...

  1. The Effect of Size and Ecology on Extinction Susceptibility

    Science.gov (United States)

    Huynh, C.; Yuan, A.; Heim, N.; Payne, J.

    2015-12-01

    Although life on Earth first emerged as prokaryotic organisms, it eventually evolved into billions of different species. However, extinctions on Earth, especially the five mass extinctions, have decimated species. So what leads to a species survival or demise during a mass extinction? Are certain species more susceptible to extinctions based on their size and ecology? For this project, we focused on the data of marine animals. To examine the impact of size and ecology on a species's likelihood of survival, we compared the sizes and ecologies of the survivors and victims of the five mass extinctions. The ecology, or life mode, of a genus consists of the combination of tiering, motility, and feeding mechanism. Tiering refers to the animal's typical location in the water column and sediments, motility refers to its ability to move, and feeding mechanism describes the way the organism eats; together, they describe the animal's behavior. We analyzed the effect of ecology on survival using logistic regression, which compares life mode to the success or failure of a genus during each mass extinction interval. For organism size, we found the extinct organisms' mean size (both volume and length) and compared it with the average size of survivors on a graph. Our results show that while surviving genera of mass extinctions tended to be slightly larger than those that went extinct, there was no significant difference. Even though the Permian (Changhsingian) and Triassic (Rhaetian) extinctions had larger surviving species, likewise the difference was small. Ecology had a more obvious impact on the likelihood of survival; fast-moving, predatory pelagic organisms were the most likely to go extinct, while sedentary, infaunal suspension feeders had the greatest chances of survival. Overall, ecology played a greater role than size in determining the survival of a species. With this information, we can use ecology to predict which species would survive future extinctions.

  2. Comparative effects of pulmonary and parenteral Δ⁹-tetrahydrocannabinol exposure on extinction of opiate-induced conditioned aversion in rats.

    Science.gov (United States)

    Manwell, Laurie A; Mallet, Paul E

    2015-05-01

    Evidence suggesting that the endogenous cannabinoid (eCB) system can be manipulated to facilitate or impair extinction of learned behaviours has important consequences for opiate withdrawal and abstinence. We demonstrated that the fatty acid amide hydrolase (FAAH) inhibitor URB597, which increases eCB levels, facilitates extinction of a naloxone-precipitated morphine withdrawal-induced conditioned place aversion (CPA). The potential of the exogenous CB1 ligand, Δ(9)-tetrahydrocannabinol (Δ(9)-THC), to facilitate extinction of this CPA was tested. Effects of both pulmonary and parenteral Δ(9)-THC exposure were evaluated using comparable doses previously determined. Rats trained to associate a naloxone-precipitated morphine withdrawal with a floor cue were administered Δ(9)-THC-pulmonary (1, 5, 10 mg vapour inhalation) or parenteral (0.5, 1.0, 1.5 mg/kg intraperitoneal injection)-prior to each of 20 to 28 extinction/testing trials. Vapourized Δ(9)-THC facilitated extinction of the CPA in a dose- and time-dependent manner: 5 and 10 mg facilitated extinction compared to vehicle and 1 mg Δ(9)-THC. Injected Δ(9)-THC significantly impaired extinction only for the 1.0-mg/kg dose: it prolonged the CPA fourfold longer than the vehicle and 0.5- and 1.5-mg/kg doses. These data suggest that both dose and route of Δ(9)-THC administration have important consequences for its pharmacokinetic and behavioural effects; specifically, pulmonary exposure at higher doses facilitates, whereas pulmonary and parenteral exposure at lower doses impairs, rates of extinction learning for CPA. Pulmonary-administered Δ(9)-THC may prove beneficial for potentiation of extinction learning for aversive memories, such as those supporting drug-craving/seeking in opiate withdrawal syndrome, and other causes of conditioned aversions, such as illness and stress.

  3. Skin Conductance Responses and Neural Activations During Fear Conditioning and Extinction Recall Across Anxiety Disorders.

    Science.gov (United States)

    Marin, Marie-France; Zsido, Rachel G; Song, Huijin; Lasko, Natasha B; Killgore, William D S; Rauch, Scott L; Simon, Naomi M; Milad, Mohammed R

    2017-06-01

    was associated with anxiety symptom severity (r = -0.420, P = .01 for conditioning and r = -0.464, P = .004 for extinction recall) and the number of co-occuring anxiety disorders diagnosed (ηp2 = 0.137, P = .009 for conditioning and ηp2 = 0.227, P = .004 for extinction recall). Psychophysiological interaction analyses revealed that the fear network connectivity differed between healthy controls and the anxiety group during fear learning (ηp2 range between 0.088 and 0.176 and P range between 0.02 and 0.003) and extinction recall (ηp2 range between 0.111 and 0.235 and P range between 0.02 and 0.002). Despite no skin conductance response group differences during extinction recall, brain activation patterns between anxious and healthy individuals differed. These findings encourage future studies to examine the conditions longitudinally and in the context of treatment trials to improve and guide therapeutics via advanced neurobiological understanding of each disorder.

  4. Extinction in the Galaxy from surface brightnesses of ESO-LV galaxies : Testing "standard" extinction maps

    NARCIS (Netherlands)

    Choloniewski, J.; Valentijn, E. A.

    A new method for the determination of the extinction in the Galaxy is proposed. The method uses surface brightnesses of external galaxies in the B and R-bands. The observational data have been taken from the ESO-LV galaxy catalog. As a first application of our model we derive the ratio of R-band to

  5. On the trap of extinction and its elimination

    International Nuclear Information System (INIS)

    Vitanov, Nikolay K.; Dimitrova, Zlatinka I.; Kantz, Holger

    2006-01-01

    We investigate the dynamics of a system of three interacting populations in presence of extinction and substitution: each population whose number of individuals drops under some threshold value becomes extinct, and it is substituted by another population with different fitness and different coefficients of interaction with the other populations. We study the influence of extinction on the system states, which in the absence of extinction can be fixed points, limit cycles or chaotic attractors of Shilnikov kind. The extinction can destabilize each of these states. We observe two possible kinds of evolution in the destabilized system: (i) it can remain forever in the trap of extinction, i.e., the extinctions and substitutions of populations continue for indefinitely long time or (ii) it can avoid the trap of extinction by means of the substitution, i.e., the fitness and the coefficients of the interactions between the species move the system attractor away from the zone of the threshold values, the extinction stops, and the system settles on a new attractor. The obtained results are discussed from the point of view of products competing for the preference of buyers that can change their opinion

  6. Brain structural connectivity and context-dependent extinction memory.

    Science.gov (United States)

    Hermann, Andrea; Stark, Rudolf; Blecker, Carlo R; Milad, Mohammed R; Merz, Christian J

    2017-08-01

    Extinction of conditioned fear represents an important mechanism in the treatment of anxiety disorders. Return of fear after successful extinction or exposure therapy in patients with anxiety disorders might be linked to poor temporal or contextual generalization of extinction due to individual differences in brain structural connectivity. The goal of this magnetic resonance imaging study was therefore to investigate the association of context-dependent extinction recall with brain structural connectivity. Diffusion-tensor imaging was used to determine the fractional anisotropy as a measure of white matter structural integrity of fiber tracts connecting central brain regions of the fear and extinction circuit (uncinate fasciculus, cingulum). Forty-five healthy men participated in a two-day fear conditioning experiment with fear acquisition in context A and extinction learning in context B on the first day. Extinction recall in the extinction context as well as renewal in the acquisition context and a novel context C took place one day later. Renewal of conditioned fear (skin conductance responses) in the acquisition context was associated with higher structural integrity of the hippocampal part of the cingulum. Enhanced structural integrity of the cingulum might be related to stronger hippocampal modulation of the dorsal anterior cingulate cortex, a region important for modulating conditioned fear output by excitatory projections to the amygdala. This finding underpins the crucial role of individual differences in the structural integrity of relevant fiber tracts for context-dependent extinction recall and return of fear after exposure therapy in anxiety disorders. © 2017 Wiley Periodicals, Inc.

  7. Bilateral Alternating Auditory Stimulations Facilitate Fear Extinction and Retrieval

    Directory of Open Access Journals (Sweden)

    Sarah Boukezzi

    2017-06-01

    Full Text Available Disruption of fear conditioning, its extinction and its retrieval are at the core of posttraumatic stress disorder (PTSD. Such deficits, especially fear extinction delay, disappear after alternating bilateral stimulations (BLS during eye movement desensitization and reprocessing (EMDR therapy. An animal model of fear recovery, based on auditory cued fear conditioning and extinction learning, recently showed that BLS facilitate fear extinction and fear extinction retrieval. Our goal was to determine if these previous results found in animals can be reproduced in humans. Twenty-two healthy participants took part in a classical fear conditioning, extinction, and extinction recall paradigm. Behavioral responses (fear expectations as well as psychophysiological measures (skin conductance responses, SCRs were recorded. The results showed a significant fear expectation decrease during fear extinction with BLS. Additionally, SCR for fear extinction retrieval were significantly lower with BLS. Our results demonstrate the importance of BLS to reduce negative emotions, and provide a successful model to further explore the neural mechanisms underlying the sole BLS effect in the EMDR.

  8. Experience with dynamic reinforcement rates decreases resistance to extinction.

    Science.gov (United States)

    Craig, Andrew R; Shahan, Timothy A

    2016-03-01

    The ability of organisms to detect reinforcer-rate changes in choice preparations is positively related to two factors: the magnitude of the change in rate and the frequency with which rates change. Gallistel (2012) suggested similar rate-detection processes are responsible for decreases in responding during operant extinction. Although effects of magnitude of change in reinforcer rate on resistance to extinction are well known (e.g., the partial-reinforcement-extinction effect), effects of frequency of changes in rate prior to extinction are unknown. Thus, the present experiments examined whether frequency of changes in baseline reinforcer rates impacts resistance to extinction. Pigeons pecked keys for variable-interval food under conditions where reinforcer rates were stable and where they changed within and between sessions. Overall reinforcer rates between conditions were controlled. In Experiment 1, resistance to extinction was lower following exposure to dynamic reinforcement schedules than to static schedules. Experiment 2 showed that resistance to presession feeding, a disruptor that should not involve change-detection processes, was unaffected by baseline-schedule dynamics. These findings are consistent with the suggestion that change detection contributes to extinction. We discuss implications of change-detection processes for extinction of simple and discriminated operant behavior and relate these processes to the behavioral-momentum based approach to understanding extinction. © 2016 Society for the Experimental Analysis of Behavior.

  9. Has the Earth's sixth mass extinction already arrived?

    Science.gov (United States)

    Barnosky, Anthony D; Matzke, Nicholas; Tomiya, Susumu; Wogan, Guinevere O U; Swartz, Brian; Quental, Tiago B; Marshall, Charles; McGuire, Jenny L; Lindsey, Emily L; Maguire, Kaitlin C; Mersey, Ben; Ferrer, Elizabeth A

    2011-03-03

    Palaeontologists characterize mass extinctions as times when the Earth loses more than three-quarters of its species in a geologically short interval, as has happened only five times in the past 540 million years or so. Biologists now suggest that a sixth mass extinction may be under way, given the known species losses over the past few centuries and millennia. Here we review how differences between fossil and modern data and the addition of recently available palaeontological information influence our understanding of the current extinction crisis. Our results confirm that current extinction rates are higher than would be expected from the fossil record, highlighting the need for effective conservation measures.

  10. Spatially Synchronous Extinction of Species under External Forcing

    Science.gov (United States)

    Amritkar, R. E.; Rangarajan, Govindan

    2006-06-01

    More than 99% of the species that ever existed on the surface of the Earth are now extinct and their extinction on a global scale has been a puzzle. One may think that a species under an external threat may survive in some isolated locations leading to the revival of the species. Using a general model we show that, under a common external forcing, the species with a quadratic saturation term first undergoes spatial synchronization and then extinction. The effect can be observed even when the external forcing acts only on some locations provided the dynamics contains a synchronizing term. Absence of the quadratic saturation term can help the species to avoid extinction.

  11. Variation in extinction risk among birds: chance or evolutionary predisposition?

    Science.gov (United States)

    Bennett, P. M.; Owens, I. P. F.

    1997-01-01

    Collar et al. (1994) estimate that of the 9,672 extant species of bird, 1,111 are threatened by extinction. Here, we test whether these threatened species are simply a random sample of birds, or whether there is something about their biology that predisposes them to extinction. We ask three specific questions. First, is extinction risk randomly distributed among families? Second, which families, if any, contain more, or less, threatened species than would be expected by chance? Third, is variation between taxa in extinction risk associated with variation in either body size or fecundity? Extinction risk is not randomly distributed among families. The families which contain significantly more threatened species than expected are the parrots (Psittacidae), pheasants and allies (Phasianidae), albatrosses and allies (Procellariidae), rails (Rallidae), cranes (Gruidae), cracids (Cracidae), megapodes (Megapodidae) and pigeons (Columbidae). The only family which contains significantly fewer threatened species than expected is the woodpeckers (Picidae). Extinction risk is also not distributed randomly with respect to fecundity or body size. Once phylogeny has been controlled for, increases in extinction risk are independently associated with increases in body size and decreases in fecundity. We suggest that this is because low rates of fecundity, which evolved many tens of millions of years ago, predisposed certain lineages to extinction. Low-fecundity populations take longer to recover if they are reduced to small sizes and are, therefore, more likely to go extinct if an external force causes an increase in the rate of mortality, thereby perturbing the natural balance between fecundity and mortality.

  12. Extinction of Learned Fear Induces Hippocampal Place Cell Remapping

    Science.gov (United States)

    Wang, Melissa E.; Yuan, Robin K.; Keinath, Alexander T.; Ramos Álvarez, Manuel M.

    2015-01-01

    The extinction of learned fear is a hippocampus-dependent process thought to embody new learning rather than erasure of the original fear memory, although it is unknown how these competing contextual memories are represented in the hippocampus. We previously demonstrated that contextual fear conditioning results in hippocampal place cell remapping and long-term stabilization of novel representations. Here we report that extinction learning also induces place cell remapping in C57BL/6 mice. Specifically, we observed cells that preferentially remapped during different stages of learning. While some cells remapped in both fear conditioning and extinction, others responded predominantly during extinction, which may serve to modify previous representations as well as encode new safe associations. Additionally, we found cells that remapped primarily during fear conditioning, which could facilitate reacquisition of the original fear association. Moreover, we also observed cells that were stable throughout learning, which may serve to encode the static aspects of the environment. The short-term remapping observed during extinction was not found in animals that did not undergo fear conditioning, or when extinction was conducted outside of the conditioning context. Finally, conditioning and extinction produced an increase in spike phase locking to the theta and gamma frequencies. However, the degree of remapping seen during conditioning and extinction only correlated with gamma synchronization. Our results suggest that the extinction learning is a complex process that involves both modification of pre-existing memories and formation of new ones, and these traces coexist within the same hippocampal representation. PMID:26085635

  13. Genetic disruptions of Drosophila Pavlovian learning leave extinction learning intact.

    Science.gov (United States)

    Qin, H; Dubnau, J

    2010-03-01

    Individuals who experience traumatic events may develop persistent posttraumatic stress disorder. Patients with this disorder are commonly treated with exposure therapy, which has had limited long-term success. In experimental neurobiology, fear extinction is a model for exposure therapy. In this behavioral paradigm, animals are repeatedly exposed in a safe environment to the fearful stimulus, which leads to greatly reduced fear. Studying animal models of extinction already has lead to better therapeutic strategies and development of new candidate drugs. Lack of a powerful genetic model of extinction, however, has limited progress in identifying underlying molecular and genetic factors. In this study, we established a robust behavioral paradigm to study the short-term effect (acquisition) of extinction in Drosophila melanogaster. We focused on the extinction of olfactory aversive 1-day memory with a task that has been the main workhorse for genetics of memory in flies. Using this paradigm, we show that extinction can inhibit each of two genetically distinct forms of consolidated memory. We then used a series of single-gene mutants with known impact on associative learning to examine the effects on extinction. We find that extinction is intact in each of these mutants, suggesting that extinction learning relies on different molecular mechanisms than does Pavlovian learning.

  14. Featured Image: Extinction in Our Inner Galaxy

    Science.gov (United States)

    Kohler, Susanna

    2017-11-01

    In this map of the innermost galaxy, which spans only a few square degrees at the Milky Ways center, we can seethe locations of more than 31 million objects obtained from the VISTA Variables in the Va Lctea (VVV) survey. This near-infrared atlas traces stellar populations in the inner Milky Way that are dimmed and reddened by interstellar dust and gas a process known as extinction in a predictable way. Led by Javier Alonso-Garca (University of Antofagasta and the Millennium Institute of Astrophysics in Chile), a team of scientists has now used the VVV measurements of these stars to better understand the distribution of gas and dust that causes extinction in our inner galaxy particularly in the most central, highly reddened, and crowded areas of the Milky Way. For more information, check out the paper below.CitationJavier Alonso-Garca et al 2017 ApJL 849 L13. doi:10.3847/2041-8213/aa92c3

  15. Dinosaur extinction: closing the '3 m gap'.

    Science.gov (United States)

    Lyson, Tyler R; Bercovici, Antoine; Chester, Stephen G B; Sargis, Eric J; Pearson, Dean; Joyce, Walter G

    2011-12-23

    Modern debate regarding the extinction of non-avian dinosaurs was ignited by the publication of the Cretaceous-Tertiary (K-T) asteroid impact theory and has seen 30 years of dispute over the position of the stratigraphically youngest in situ dinosaur. A zone devoid of dinosaur fossils reported from the last 3 m of the Upper Cretaceous, coined the '3 m gap', has helped drive controversy. Here, we report the discovery of the stratigraphically youngest in situ dinosaur specimen: a ceratopsian brow horn found in a poorly rooted, silty, mudstone floodplain deposit located no more than 13 cm below the palynologically defined boundary. The K-T boundary is identified using three criteria: (i) decrease in Cretaceous palynomorphs without subsequent recovery, (ii) the existence of a 'fern spike', and (iii) correlation to a nearby stratigraphic section where primary extraterrestrial impact markers are present (e.g. iridium anomaly, spherules, shocked quartz). The in situ specimen demonstrates that a gap devoid of non-avian dinosaur fossils does not exist and is inconsistent with the hypothesis that non-avian dinosaurs were extinct prior to the K-T boundary impact event.

  16. Interaction of basolateral amygdala, ventral hippocampus and medial prefrontal cortex regulates the consolidation and extinction of social fear.

    Science.gov (United States)

    Qi, Chu-Chu; Wang, Qing-Jun; Ma, Xue-Zhu; Chen, Hai-Chao; Gao, Li-Ping; Yin, Jie; Jing, Yu-Hong

    2018-03-19

    Following a social defeat, the balanced establishment and extinction of aversive information is a beneficial strategy for individual survival. Abnormal establishment or extinction is implicated in the development of mental disorders. This study investigated the time course of the establishment and extinction of aversive information from acute social defeat and the temporal responsiveness of the basolateral amygdala (BLA), ventral hippocampus (vHIP) and medial prefrontal cortex (mPFC) in this process. Mouse models of acute social defeat were established by using the resident-intruder paradigm. To evaluate the engram of social defeat, the intruder mice were placed into the novel context at designated time to test the social behavior. Furthermore, responses of BLA, vHIP and mPFC were investigated by analyzing the expression of immediate early genes, such as zif268, arc, and c-fos. The results showed after an aggressive attack, aversive memory was maintained for approximately 7 days before gradually diminishing. The establishment and maintenance of aversive stimulation were consistently accompanied by BLA activity. By contrast, vHIP and mPFC response was inhibited from this process. Additionally, injecting muscimol (Mus), a GABA receptor agonist, into the BLA alleviated the freezing behavior and social fear and avoidance. Simultaneously, Mus treatment decreased the zif268 and arc expression in BLA, but it increased their expression in vHIP. Our data support and extend earlier findings that implicate BLA, vHIP and mPFC in social defeat. The time courses of the establishment and extinction of social defeat are particularly consistent with the contrasting BLA and vHIP responses involved in this process.

  17. A robust nonparametric method for quantifying undetected extinctions.

    Science.gov (United States)

    Chisholm, Ryan A; Giam, Xingli; Sadanandan, Keren R; Fung, Tak; Rheindt, Frank E

    2016-06-01

    How many species have gone extinct in modern times before being described by science? To answer this question, and thereby get a full assessment of humanity's impact on biodiversity, statistical methods that quantify undetected extinctions are required. Such methods have been developed recently, but they are limited by their reliance on parametric assumptions; specifically, they assume the pools of extant and undetected species decay exponentially, whereas real detection rates vary temporally with survey effort and real extinction rates vary with the waxing and waning of threatening processes. We devised a new, nonparametric method for estimating undetected extinctions. As inputs, the method requires only the first and last date at which each species in an ensemble was recorded. As outputs, the method provides estimates of the proportion of species that have gone extinct, detected, or undetected and, in the special case where the number of undetected extant species in the present day is assumed close to zero, of the absolute number of undetected extinct species. The main assumption of the method is that the per-species extinction rate is independent of whether a species has been detected or not. We applied the method to the resident native bird fauna of Singapore. Of 195 recorded species, 58 (29.7%) have gone extinct in the last 200 years. Our method projected that an additional 9.6 species (95% CI 3.4, 19.8) have gone extinct without first being recorded, implying a true extinction rate of 33.0% (95% CI 31.0%, 36.2%). We provide R code for implementing our method. Because our method does not depend on strong assumptions, we expect it to be broadly useful for quantifying undetected extinctions. © 2016 Society for Conservation Biology.

  18. Climate change, elevational range shifts, and bird extinctions.

    Science.gov (United States)

    Sekercioglu, Cagan H; Schneider, Stephen H; Fay, John P; Loarie, Scott R

    2008-02-01

    Limitations imposed on species ranges by the climatic, ecological, and physiological effects of elevation are important determinants of extinction risk. We modeled the effects of elevational limits on the extinction risk of landbirds, 87% of all bird species. Elevational limitation of range size explained 97% of the variation in the probability of being in a World Conservation Union category of extinction risk. Our model that combined elevational ranges, four Millennium Assessment habitat-loss scenarios, and an intermediate estimate of surface warming of 2.8 degrees C, projected a best guess of 400-550 landbird extinctions, and that approximately 2150 additional species would be at risk of extinction by 2100. For Western Hemisphere landbirds, intermediate extinction estimates based on climate-induced changes in actual distributions ranged from 1.3% (1.1 degrees C warming) to 30.0% (6.4 degrees C warming) of these species. Worldwide, every degree of warming projected a nonlinear increase in bird extinctions of about 100-500 species. Only 21% of the species predicted to become extinct in our scenarios are currently considered threatened with extinction. Different habitat-loss and surface-warming scenarios predicted substantially different futures for landbird species. To improve the precision of climate-induced extinction estimates, there is an urgent need for high-resolution measurements of shifts in the elevational ranges of species. Given the accelerating influence of climate change on species distributions and conservation, using elevational limits in a tested, standardized, and robust manner can improve conservation assessments of terrestrial species and will help identify species that are most vulnerable to global climate change. Our climate-induced extinction estimates are broadly similar to those of bird species at risk from other factors, but these estimates largely involve different sets of species.

  19. 3,4-Methylenedioxymethamphetamine facilitates fear extinction learning.

    Science.gov (United States)

    Young, M B; Andero, R; Ressler, K J; Howell, L L

    2015-09-15

    Acutely administered 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') has been proposed to have long-term positive effects on post-traumatic stress disorder (PTSD) symptoms when combined with psychotherapy. No preclinical data support a mechanistic basis for these claims. Given the persistent nature of psychotherapeutic gains facilitated by MDMA, we hypothesized that MDMA improves fear extinction learning, a key process in exposure-based therapies for PTSD. In these experiments, mice were first exposed to cued fear conditioning and treated with drug vehicle or MDMA before extinction training 2 days later. MDMA was administered systemically and also directly targeted to brain structures known to contribute to extinction. In addition to behavioral measures of extinction, changes in mRNA levels of brain-derived neurotrophic factor (Bdnf) and Fos were measured after MDMA treatment and extinction. MDMA (7.8 mg kg(-1)) persistently and robustly enhanced long-term extinction when administered before extinction training. MDMA increased the expression of Fos in the amygdala and medial prefrontal cortex (mPFC), whereas increases in Bdnf expression were observed only in the amygdala after extinction training. Extinction enhancements were recapitulated when MDMA (1 μg) was infused directly into the basolateral complex of the amygdala (BLA), and enhancement was abolished when BDNF signaling was inhibited before extinction. These findings suggest that MDMA enhances fear memory extinction through a BDNF-dependent mechanism, and that MDMA may be a useful adjunct to exposure-based therapies for PTSD and other anxiety disorders characterized by altered fear learning.

  20. Load alleviation of wind turbines by yaw misalignment

    DEFF Research Database (Denmark)

    Kragh, Knud Abildgaard; Hansen, Morten Hartvig

    2014-01-01

    Vertical wind shear is one of the dominating causes of load variations on the blades of a horizontal axis wind turbine. To alleviate the varying loads, wind turbine control systems have been augmented with sensors and actuators for individual pitch control. However, the loads caused by a vertical...... wind shear can also be affected through yaw misalignment. Recent studies of yaw control have been focused on improving the yaw alignment to increase the power capture at below rated wind speeds. In this study, the potential of alleviating blade load variations induced by the wind shear through yaw...... misalignment is assessed. The study is performed through simulations of a reference turbine. The study shows that optimal yaw misalignment angles for minimizing the blade load variations can be identified for both deterministic and turbulent inflows. It is shown that the optimal yaw misalignment angles can...

  1. FISHERMEN ALLEVIATION POVERTY MODEL IN THE NORTH COASTAL EAST JAVA

    Directory of Open Access Journals (Sweden)

    Roziana Ainul Hidayati

    2011-12-01

    Full Text Available Poverty is a multidimensional problem that the approach to eradicate poverty must also be multidimensional. The study aims to formulate a model of poverty alleviation in coastal fishing in the North Coast of East Java. Grounded research approach used to determine the causes, impacts and implications of poverty fishermen. The results showed that the main cause of poverty that occurred in the three districts in East Java's north coast is different from one another. In Gresik district, the major cause of poverty is law enforcements that do not support fishermen and overfishing. While Lamongan more due to low fish prices and capital problems. While in Tuban fishermen due to limited infrastructure and lazy and extravagant lifestyle of the fishermen. These differences lead to different coping strategies so that later can form a concept model of poverty alleviation North Coast fishermen in East Java.

  2. Islamic Microfinance: an Interest free Microfinance Model for Poverty Alleviation

    Directory of Open Access Journals (Sweden)

    Amit Kumar Chakrabarty

    2015-01-01

    Full Text Available This theoretical paper deals with Islamic microfinance and its rationality in Indian context as a panacea of Muslim poverty. Conventional microfinance system is very effective to alleviate poverty of developing countries. But it could not touch all community of people because of ‘interest’ component in debt and high degree of interest. Muslims dislike that microfinance which is based on ‘interest’ as it is strictly prohibited in Islam. Therefore the motto of financial inclusion is out of reach through conventional microfinance. An alternative interest free microfinance model has been developed in some part of world to include all Muslim poor people within the banking system. India is yet to adopt Islamic microfinance though 20% of total population is Muslim. The author strongly opines that India should adopt Islamic microfinance as a tool for poverty alleviation of Muslims as well as other communities.

  3. Elevatated CO2 alleviates heat stress tolerance in wheat

    DEFF Research Database (Denmark)

    Kjær, Katrine Heinsvig; Rosenqvist, Eva S. K.; Ottosen, Carl-Otto

    2014-01-01

    Title: The alleviating effect of elevated CO2 on heat stress susceptibility of two wheat (Triticum aestivum L.) cultivars Session: Plant response and adaptation to abiotic stress Sindhuja Shanmugam1, Katrine Heinsvig Kjaer2*, Carl-Otto Ottosen2, Eva Rosenqvist3, Dew Kumari Sharma3 and Bernd...... Wollenweber4 1Department of Bioenergy, Tamilnadu Agricultural University, Coimbatore, India. 2Department of Food Science, Aarhus University, Kirstinebjergvej 10, 5792 Årslev, Denmark 3Institute of Agricultural Sciences and Ecology, University of Copenhagen, Hojbakkegaard Allé 9, 2630 Taastrup, Denmark 4......Institute for Agroecology, Aarhus University, Forsøgsvej 1, 4200 Slagelse, Denmark *Presenting author This study analysed the alleviating effect of elevated CO2 on stress-induced decreases in photosynthesis and changes in carbohydrate metabolism in two wheat cultivars (Triticum aestivum L.) of different...

  4. Deepened Extinction following Compound Stimulus Presentation: Noradrenergic Modulation

    Science.gov (United States)

    Janak, Patricia H.; Corbit, Laura H.

    2011-01-01

    Behavioral extinction is an active form of new learning involving the prediction of nonreward where reward has previously been present. The expression of extinction learning can be disrupted by the presentation of reward itself or reward-predictive stimuli (reinstatement) as well as the passage of time (spontaneous recovery) or contextual changes…

  5. Asymptotic behaviour near extinction of continuous-state branching processes

    OpenAIRE

    Berzunza, Gabriel; Pardo, Juan Carlos

    2016-01-01

    In this note, we study the asymptotic behaviour near extinction of (sub-) critical continuous state branching processes. In particular, we establish an analogue of Khintchin's law of the iterated logarithm near extinction time for a continuous state branching process whose branching mechanism satisfies a given condition and its reflected process at its infimum.

  6. DUST EXTINCTION IN NGC-4594, THE SOMBRERO GALAXY

    NARCIS (Netherlands)

    KNAPEN, JH; HES, R; BECKMAN, JE; PELETIER, RF

    We have studied the extinction law in the well-defined dust lane of the Sombrero galaxy, NGC4594. In the R,I,J,H, and K bands we find good agreement between values for the extinction ratios A-lambda/A(v) in NGC4594 and those reported for our own Galaxy. We can explain the apparently somewhat lower

  7. Ultraviolet extinction in M-supergiant circumstellar envelopes

    International Nuclear Information System (INIS)

    Buss, R.H. Jr.; Snow, T.P. Jr.

    1986-01-01

    Using International Ultraviolet (IUS) archival low-dispersion spectra, ultraviolet spectral extinctions were derived for the circumstellar envelopes of two M supergiants: HD 60414 and HD 213310. The observed stellar systems belong to a class of widely-separated spectroscopic binaries that are called VV Cephei stars. The total extinction was calculated by dividing the reddened fluxes with unreddened comparison fluxes of similar stars (g B2.5 for HD 213310 and a normalized s+B3 for HD 60414) from the reference atlas. After substracting the interstellar extinctions, which were estimated from the E(B-V) reddening of nearby stars, the resultant circumstellar extinctions were normalized at about 3.5 inverse microns. Not only is the 2175 A extinction bump absent in the circumstellar extinctions, but the far-ultraviolet extinction rise is also absent. The rather flat, ultraviolet extinction curves were interpreted as signatures of a population of noncarbonaceous, oxygen-rich grains with diameters larger than the longest observed wavelength

  8. POST-RETRIEVAL EXTINCTION ATTENUATES ALCOHOL CUE REACTIVITY IN RATS

    Science.gov (United States)

    Cofresí, Roberto U.; Lewis, Suzanne M.; Chaudhri, Nadia; Lee, Hongjoo J.; Monfils, Marie-H.; Gonzales, Rueben A.

    2017-01-01

    BACKGROUND Conditioned responses to alcohol-associated cues can hinder recovery from alcohol use disorder (AUD). Cue exposure (extinction) therapy (CET) can reduce reactivity to alcohol cues, but its efficacy is limited by phenomena such as spontaneous recovery and reinstatement that can cause a return of conditioned responding after extinction. Using a preclinical model of alcohol cue reactivity in rats, we evaluated whether the efficacy of alcohol CET could be improved by conducting CET during the memory reconsolidation window after retrieval of a cue-alcohol association. METHODS Rats were provided with intermittent access to unsweetened alcohol. Rats were then trained to predict alcohol access based on a visual cue. Next, rats were treated with either standard extinction (n=14) or post-retrieval extinction (n=13). Rats were then tested for long-term memory of extinction and susceptibility to spontaneous recovery and reinstatement. RESULTS Despite equivalent extinction, rats treated with post-retrieval extinction exhibited reduced spontaneous recovery and reinstatement relative to rats treated with standard extinction. CONCLUSIONS Post-retrieval CET shows promise for persistently attenuating the risk to relapse posed by alcohol cues in individuals with AUD. PMID:28169439

  9. d-Cycloserine reduces context specificity of sexual extinction learning

    NARCIS (Netherlands)

    Brom, Mirte; Laan, Ellen; Everaerd, Walter; Spinhoven, Philip; Trimbos, Baptist; Both, Stephanie

    2015-01-01

    d-Cycloserine (DCS) enhances extinction processes in animals. Although classical conditioning is hypothesized to play a pivotal role in the aetiology of appetitive motivation problems, no research has been conducted on the effect of DCS on the reduction of context specificity of extinction in human

  10. About one of possible cosmic causes of extinction of organisms

    International Nuclear Information System (INIS)

    Kagramanov, Yu.R.

    2004-01-01

    Based on the analysis of diverse causes of extinction of organisms in the history of the Earth and a new hypothesis of cosmic origin of oil, a suggested new possible cause of such extinction is related to intoxication with hydrocarbons arriving from the outer space

  11. Relating plant height to demographic rates and extinction vulnerability

    NARCIS (Netherlands)

    Jonge, de Melinda M.J.; Hilbers, Jelle P.; Jongejans, Eelke; Ozinga, Wim A.; Hendriks, A.J.; Huijbregts, Mark A.J.

    2018-01-01

    To prioritize conservation efforts, it is important to know which plant species are most vulnerable to extinction. Intrinsic extinction vulnerabilities depend on demographic parameters, but for many species these demographic parameters are lacking. Body size has been successfully used as proxy of

  12. Adaptive Dynamics, Control, and Extinction in Networked Populations

    Science.gov (United States)

    2015-07-09

    network geometries. From the pre-history of paths that go extinct, a density function is created from the prehistory of these paths, and a clear local...density plots of Fig. 3b. Using the IAMM to compute the most probable path and comparing it to the prehistory of extinction events on stochastic networks

  13. A comprehensive genomic history of extinct and living elephants

    DEFF Research Database (Denmark)

    Palkopoulou, Eleftheria; Lipson, Mark; Mallick, Swapan

    2018-01-01

    Elephantids are the world's most iconic megafaunal family, yet there is no comprehensive genomic assessment of their relationships. We report a total of 14 genomes, including 2 from the American mastodon, which is an extinct elephantid relative, and 12 spanning all three extant and three extinct...

  14. Late Pleistocene and Holocene mammal extinctions on continental Africa

    Science.gov (United States)

    Faith, J. Tyler

    2014-01-01

    Understanding the cause of late Quaternary mammal extinctions is the subject of intense debate spanning the fields of archeology and paleontology. In the global context, the losses on continental Africa have received little attention and are poorly understood. This study aims to inspire new discussion of African extinctions through a review of the extinct species and the chronology and possible causes of those extinctions. There are at least 24 large mammal (> 5 kg) species known to have disappeared from continental Africa during the late Pleistocene or Holocene, indicating a much greater taxonomic breadth than previously recognized. Among the better sampled taxa, these losses are restricted to the terminal Pleistocene and early Holocene, between 13,000 and 6000 yrs ago. The African extinctions preferentially affected species that are grazers or prefer grasslands. Where good terrestrial paleoenvironmental records are present, extinctions are associated with changes in the availability, productivity, or structure of grassland habitats, suggesting that environmental changes played a decisive role in the losses. In the broader evolutionary context, these extinctions represent recent examples of selective taxonomic winnowing characterized by the loss of grassland specialists and the establishment of large mammal communities composed of more ecologically flexible taxa over the last million years. There is little reason to believe that humans played an important role in African extinctions.

  15. The Role of Forests in Poverty Alleviation: Dealing with Multiple Millennium Development Goals

    NARCIS (Netherlands)

    Wiersum, K.F.; Ros-Tonen, Mirjam A.F.

    2005-01-01

    This policy brief summarises the present state of scientific understanding of the potential contribution of tropical forests to poverty alleviation and highlights the implications of this knowledge for forest-based poverty alleviation policies

  16. Acquisition and extinction of human avoidance behavior: Attenuating effect of safety signals and associations with anxiety vulnerabilities

    Directory of Open Access Journals (Sweden)

    Jony eSheynin

    2014-09-01

    Full Text Available While avoidance behavior is often an adaptive strategy, exaggerated avoidance can be detrimental and result in the development of psychopathologies, such as anxiety disorders. A large animal literature shows that the acquisition and extinction of avoidance behavior in rodents depends on individual differences (e.g., sex, strain and might be modulated by the presence of environmental cues. However, there is a dearth of such reports in human literature, mainly due to the lack of adequate experimental paradigms. In the current study, we employed a computer-based task, where participants control a spaceship and attempt to gain points by shooting an enemy spaceship that appears on the screen. Warning signals predict on-screen aversive events; the participants can learn a protective response to escape or avoid these events. This task has been recently used to reveal facilitated acquisition of avoidance behavior in individuals with anxiety vulnerability, due to female sex or inhibited personality. Here, we extended the task to include an extinction phase, and tested the effect of signals that appeared during safe periods. Healthy young adults (n=122 were randomly assigned to a testing condition with or without such signals. Results showed that the addition of safety signals during the acquisition phase impaired acquisition (in females and facilitated extinction of the avoidance behavior. We also replicated our recent finding of an association between female sex and longer avoidance duration and further showed that females continued to demonstrate more avoidance behavior even on extinction trials when the aversive events no longer occurred. This study is the first to show sex differences on the acquisition and extinction of human avoidance behavior and to demonstrate the role of safety signals in such behavior, highlighting the potential relevance of safety signals for cognitive therapies that focus on extinction learning to treat anxiety symptoms.

  17. Macroeconomic Policies and their Impact on Poverty Alleviation in Pakistan

    OpenAIRE

    Rashid Amjad; A.R. Kemal

    1997-01-01

    The paper provides a consistent time-series of poverty estimates for the period 1963- 64 to 1992-93 for both the rural as well as the urban areas, examines the influence of macroeconomic policies on the poverty levels, analyses the impact of Structural Adjustment Programmes on the levels of poverty, and suggests a strategy for poverty alleviation in Pakistan. The paper explores in particular the influence on poverty of such factors as economic growth, agricultural growth, terms of trade for t...

  18. Effectiveness of microcredit for poverty alleviation: evidence from Indonesia

    OpenAIRE

    Arp, Frithjof; Ardisa, Alvin

    2016-01-01

    Debate persists about the effectiveness of microcredit for poverty alleviation. We argue that much of this debate is due to discipline-specific research approaches and methodological complexities obscuring fundamental issues. Microfinance organisations do not operate in a vacuum: other forms of collateral-free lending must be taken into account. We illustrate our argument with a study of formal and informal collateral-free lending in the Yogyakarta region of Indonesia. Focused on the fundame...

  19. A model of amygdala-hippocampal-prefrontal interaction in fear conditioning and extinction in animals

    Science.gov (United States)

    Moustafa, Ahmed A.; Gilbertson, Mark W.; Orr, Scott P.; Herzallah, Mohammad M.; Servatius, Richard. J.; Myers, Catherine E.

    2012-01-01

    Empirical research has shown that the amygdala, hippocampus, and ventromedial prefrontal cortex (vmPFC) are involved in fear conditioning. However, the functional contribution of each brain area and the nature of their interactions are not clearly understood. Here, we extend existing neural network models of the functional roles of the hippocampus in classical conditioning to include interactions with the amygdala and prefrontal cortex. We apply the model to fear conditioning, in which animals learn physiological (e.g. heart rate) and behavioral (e.g. freezing) responses to stimuli that have been paired with a highly aversive event (e.g. electrical shock). The key feature of our model is that learning of these conditioned responses in the central nucleus of the amygdala is modulated by two separate processes, one from basolateral amygdala and signaling a positive prediction error, and one from the vmPFC, via the intercalated cells of the amygdala, and signaling a negative prediction error. In addition, we propose that hippocampal input to both vmPFC and basolateral amygdala is essential for contextual modulation of fear acquisition and extinction. The model is sufficient to account for a body of data from various animal fear conditioning paradigms, including acquisition, extinction, reacquisition, and context specificity effects. Consistent with studies on lesioned animals, our model shows that damage to the vmPFC impairs extinction, while damage to the hippocampus impairs extinction in a different context (e.g., a different conditioning chamber from that used in initial training in animal experiments). We also discuss model limitations and predictions, including the effects of number of training trials on fear conditioning. PMID:23164732

  20. Bidirectional modulation of taste aversion extinction by insular cortex LTP and LTD.

    Science.gov (United States)

    Rodríguez-Durán, Luis F; Martínez-Moreno, Araceli; Escobar, Martha L

    2017-07-01

    The history of activity of a given neuron has been proposed to bidirectionally influence its future response to synaptic inputs. In particular, induction of synaptic plasticity expressions such as long-term potentiation (LTP) and long-term depression (LTD) modifies the performance of several behavioral tasks. Our previous studies in the insular cortex (IC), a neocortical region that has been related to acquisition and retention of conditioned taste aversion (CTA), have demonstrated that induction of LTP in the basolateral amygdaloid nucleus (Bla)-IC pathway before CTA training enhances the retention of this task. In addition, we reported that CTA training triggers a persistent impairment in the ability to induce in vivo LTP in the IC. The aim of the present study was to investigate whether LTD can be induced in the Bla-IC projection in vivo, as well as, whether the extinction of CTA is bidirectionally modified by previous synaptic plasticity induction in this pathway. Thus, rats received 900 train pulses (five 250μs pulses at 250Hz) delivered at 1Hz in the Bla-IC projection in order to induce LTD or 10 trains of 100Hz/1s with an intertrain interval of 20s in order to induce LTP. Seven days after surgery, rats were trained in the CTA task including the extinction trials. Our results show that the Bla-IC pathway is able to express in vivo LTD in an N-Methyl-D-aspartate (NMDA) receptor-dependent manner. Induction of LTD in the Bla-IC projection previous to CTA training facilitates the extinction of this task. Conversely, LTP induction enhances CTA retention. The present results show the bidirectional modulation of CTA extinction in response to IC-LTP and LTD, providing evidence of the homeostatic adaptation of taste learning. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. A study of helicopter gust response alleviation by automatic control

    Science.gov (United States)

    Saito, S.

    1983-01-01

    Two control schemes designed to alleviate gust-induced vibration are analytically investigated for a helicopter with four articulated blades. One is an individual blade pitch control scheme. The other is an adaptive blade pitch control algorithm based on linear optimal control theory. In both controllers, control inputs to alleviate gust response are superimposed on the conventional control inputs required to maintain the trim condition. A sinusoidal vertical gust model and a step gust model are used. The individual blade pitch control, in this research, is composed of sensors and a pitch control actuator for each blade. Each sensor can detect flapwise (or lead-lag or torsionwise) deflection of the respective blade. The acturator controls the blade pitch angle for gust alleviation. Theoretical calculations to predict the performance of this feedback system have been conducted by means of the harmonic method. The adaptive blade pitch control system is composed of a set of measurements (oscillatory hub forces and moments), an identification system using a Kalman filter, and a control system based on the minimization of the quadratic performance function.

  2. Factors Influencing Poverty Alleviation amongst Microfinance Adopting Households in Zambia

    Directory of Open Access Journals (Sweden)

    Mavhungu Abel Mafukata

    2016-01-01

    Full Text Available The main objective of this paper is to investigate the factors having the most influence on the alleviation of poverty amongst the households adopting microfinance in Zambia. Ninety nine (n=99 respondents were randomly and purposively selected from amongst 340 microfinance adopters of the so-called Micro Bankers Trust programme operating a microfinance business in the Makululu Compound of Kabwe, Zambia. Socio-demographic primary data were collected through face-to-face interviews based on a semi-structured questionnaire instrument. The data were entered into an excel spreadsheet for analysis. The descriptive data were thereafter exported and fitted to an empirical model. The descriptive results revealed that the majority of the respondents were married, unemployed, fairly educated younger women from larger-sized poor households who drew their household income mainly from microfinance activities. The majority of the respondents thought microfinance had improved their well-being in some crucial areas. The results of the empirical model found that some respondents were indeed alleviated from poverty through microfinance. Conclusion drawn in this paper is that microfinance does alleviate poverty of the poor.

  3. EFFECTS OF SILICON ON ALLEVIATING ARSENIC TOXICITY IN MAIZE PLANTS

    Directory of Open Access Journals (Sweden)

    Airon José da Silva

    2015-02-01

    Full Text Available Arsenic is a metalloid highly toxic to plants and animals, causing reduced plant growth and various health problems for humans and animals. Silicon, however, has excelled in alleviating stress caused by toxic elements in plants. The aim of this study was to investigate the effects of Si in alleviating As stress in maize plants grown in a nutrient solution and evaluate the potential of the spectral emission parameters and the red fluorescence (Fr and far-red fluorescence (FFr ratio obtained in analysis of chlorophyll fluorescence in determination of this interaction. An experiment was carried out in a nutrient solution containing a toxic rate of As (68 μmol L-1 and six increasing rates of Si (0, 0.25, 0.5, 1.0, 1.5, and 2.0 mmol L-1. Dry matter production and concentrations of As, Si, and photosynthetic pigments were then evaluated. Chlorophyll fluorescence was also measured throughout plant growth. Si has positive effects in alleviating As stress in maize plants, evidenced by the increase in photosynthetic pigments. Silicon application resulted in higher As levels in plant tissue; therefore, using Si for soil phytoremediation may be a promising choice. Chlorophyll fluorescence analysis proved to be a sensitive tool, and it can be successfully used in the study of the ameliorating effects of Si in plant protection, with the Fr/FFr ratio as the variable recommended for identification of temporal changes in plants.

  4. Coherent Lidar Turbulence Measurement for Gust Load Alleviation

    Science.gov (United States)

    Bogue, Rodney K.; Ehernberger, L. J.; Soreide, David; Bagley, Hal

    1996-01-01

    Atmospheric turbulence adversely affects operation of commercial and military aircraft and is a design constraint. The airplane structure must be designed to survive the loads imposed by turbulence. Reducing these loads allows the airplane structure to be lighter, a substantial advantage for a commercial airplane. Gust alleviation systems based on accelerometers mounted in the airplane can reduce the maximum gust loads by a small fraction. These systems still represent an economic advantage. The ability to reduce the gust load increases tremendously if the turbulent gust can be measured before the airplane encounters it. A lidar system can make measurements of turbulent gusts ahead of the airplane, and the NASA Airborne Coherent Lidar for Advanced In-Flight Measurements (ACLAIM) program is developing such a lidar. The ACLAIM program is intended to develop a prototype lidar system for use in feasibility testing of gust load alleviation systems and other airborne lidar applications, to define applications of lidar with the potential for improving airplane performance, and to determine the feasibility and benefits of these applications. This paper gives an overview of the ACLAIM program, describes the lidar architecture for a gust alleviation system, and describes the prototype ACLAIM lidar system.

  5. Poverty alleviation programmes in India: a social audit.

    Science.gov (United States)

    K Yesudian, C A

    2007-10-01

    The review highlights the poverty alleviation programmes of the government in the post-economic reform era to evaluate the contribution of these programmes towards reducing poverty in the country. The poverty alleviation programmes are classified into (i) self-employment programmes; (ii) wage employment programmes; (iii) food security programmes; (iv) social security programmes; and (v) urban poverty alleviation programmes. The parameter used for evaluation included utilization of allocated funds, change in poverty level, employment generation and number or proportion of beneficiaries. The paper attempts to go beyond the economic benefit of the programmes and analyzes the social impact of these programmes on the communities where the poor live, and concludes that too much of government involvement is actually an impediment. On the other hand, involvement of the community, especially the poor has led to better achievement of the goals of the programmes. Such endeavours not only reduced poverty but also empowered the poor to find their own solutions to their economic problems. There is a need for decentralization of the programmes by strengthening the panchayat raj institutions as poverty is not merely economic deprivation but also social marginalization that affects the poor most.

  6. Environmental stresses can alleviate the average deleterious effect of mutations

    Directory of Open Access Journals (Sweden)

    Leibler Stanislas

    2003-05-01

    Full Text Available Abstract Background Fundamental questions in evolutionary genetics, including the possible advantage of sexual reproduction, depend critically on the effects of deleterious mutations on fitness. Limited existing experimental evidence suggests that, on average, such effects tend to be aggravated under environmental stresses, consistent with the perception that stress diminishes the organism's ability to tolerate deleterious mutations. Here, we ask whether there are also stresses with the opposite influence, under which the organism becomes more tolerant to mutations. Results We developed a technique, based on bioluminescence, which allows accurate automated measurements of bacterial growth rates at very low cell densities. Using this system, we measured growth rates of Escherichia coli mutants under a diverse set of environmental stresses. In contrast to the perception that stress always reduces the organism's ability to tolerate mutations, our measurements identified stresses that do the opposite – that is, despite decreasing wild-type growth, they alleviate, on average, the effect of deleterious mutations. Conclusions Our results show a qualitative difference between various environmental stresses ranging from alleviation to aggravation of the average effect of mutations. We further show how the existence of stresses that are biased towards alleviation of the effects of mutations may imply the existence of average epistatic interactions between mutations. The results thus offer a connection between the two main factors controlling the effects of deleterious mutations: environmental conditions and epistatic interactions.

  7. Foods provoking and alleviating symptoms in gastroparesis: patient experiences.

    Science.gov (United States)

    Wytiaz, Victoria; Homko, Carol; Duffy, Frank; Schey, Ron; Parkman, Henry P

    2015-04-01

    Nutritional counseling for gastroparesis focuses on reduction of meal size, fiber, and fat to control symptoms. The tolerance of gastroparesis patients for particular foods is largely anecdotal. The aim of this study was to identify and characterize foods provoking or alleviating gastroparesis symptoms. Gastroparesis patients completed: (1) Demographic Questionnaire; (2) Patient Assessment of Upper GI Symptoms; (3) Food Toleration and Aversion survey asking patients about experiences when eating certain foods utilizing a scale from -3 (greatly worsening symptoms) to +3 (greatly improving symptoms). Descriptive qualities (acidic, fatty, spicy, roughage-based, bitter, salty, bland, and sweet) were assigned to foods. Forty-five gastroparesis patients participated (39 idiopathic gastroparesis). Foods worsening symptoms included: orange juice, fried chicken, cabbage, oranges, sausage, pizza, peppers, onions, tomato juice, lettuce, coffee, salsa, broccoli, bacon, and roast beef. Saltine crackers, jello, and graham crackers moderately improved symptoms. Twelve additional foods were tolerated by patients (not provoking symptoms): ginger ale, gluten-free foods, tea, sweet potatoes, pretzels, white fish, clear soup, salmon, potatoes, white rice, popsicles, and applesauce. Foods provoking symptoms were generally fatty, acidic, spicy, and roughage-based. The foods shown to be tolerable were generally bland, sweet, salty, and starchy. This study identified specific foods that worsen as well as foods that may help alleviate symptoms of gastroparesis. Foods that provoked symptoms differed in quality from foods that alleviated symptoms or were tolerable. The results of this study illustrate specific examples of foods that aggravate or improve symptoms and provide suggestions for a gastroparesis diet.

  8. Theoretical investigation of the extinction coefficient of magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Fang Xiaopeng; Xuan Yimin, E-mail: ymxuan@mail.njust.edu.cn; Li Qiang [Nanjing University of Science and Technology, School of Energy and Power Engineering (China)

    2013-05-15

    A new theoretical approach for calculating the extinction coefficient of magnetic fluid is proposed, which is based on molecular dynamics (MD) simulation and T-matrix method. By means of this approach, the influence of particle diameter, particle volume fraction, and external magnetic filed on the extinction coefficient of magnetic fluid is investigated. The results show that the extinction coefficient of the magnetic fluid linearly increases with increase in the particle volume fraction. For a given particle volume fraction, the extinction coefficient increases with increase in the particle diameter which varies from 5 to 20 nm. When a uniform external magnetic filed is applied to the magnetic fluid, the extinction coefficient of the magnetic fluid presents an anisotropic feature. These results agree well with the reported experimental results. The proposed approach is applicable to investigating the optical properties of magnetic fluids.

  9. Adrenalectomy eliminates the extinction spike in autoshaping with rats.

    Science.gov (United States)

    Thomas, B L; Papini, M R

    2001-03-01

    Experiment 1, using rats, investigated the effect of adrenalectomy (ADX) on the invigoration of lever-contact performance that occurs in the autoshaping situation after a shift from acquisition to extinction (called the extinction spike). Groups of rats with ADX or sham operations were trained under spaced and massed conditions [average intertrial intervals (ITI) of either 15 or 90 s] for 10 sessions and then shifted to extinction. ADX did not affect acquisition training but it eliminated the extinction spike. Plasma corticosterone levels during acquisition were shown in Experiment 2 to be similar in rats trained under spaced or massed conditions. Adrenal participation in the emotional arousal induced by conditions of surprising nonreward (e.g., extinction) is discussed.

  10. How to detect and visualize extinction thresholds for structured PVA models

    NARCIS (Netherlands)

    Hildenbrandt, H.; Grimm, V.

    2006-01-01

    An extinction threshold is a population size below which extinction risk increases to beyond critical values. However, detecting extinction thresholds for structured population models is not straightforward because many different population structures may correspond to the same population size.

  11. Unpaired shocks during extinction weaken the contextual renewal of a conditioned discrimination

    NARCIS (Netherlands)

    Vervliet, B.; Vansteenwegen, D.; Hermans, D.

    2010-01-01

    Extinction is generally more fragile than conditioning, as illustrated by the contextual renewal effect. The traditional extinction procedure entails isolated presentations of the conditioned stimulus. Extinction may be boosted by adding isolated presentations of the unconditioned stimulus, as this

  12. Demography and the extinction of European Neanderthals

    DEFF Research Database (Denmark)

    Sørensen, Bent

    2011-01-01

    Causes previously suggested for the sudden extinction of Neanderthals (Homo neanderthalensis) in Europe, starting around 35,000 years ago, comprise food shortage, climatic effects and violence from Modern Humans. The aim here is to formulate a demographic model with reconstructed fertility and de...... uncertainty. Finally, the option of regional migration between northern, middle and southern Europe is added, in order to capture population movements away from a region in response to deteriorating or improving climate. This model accounts for population developments, including the re......-population of the Middle and Northern regions of Europe during and after the warm Eem period. However, parameter choices that give plausible results during the initial 210,000 years also predict that the Neanderthals should have survived the latter part of the Weichselian ice age, despite competing for food with Modern...

  13. Molar extinction coefficients of some fatty acids

    DEFF Research Database (Denmark)

    Sandhu, G.K.; Singh, K.; Lark, B.S.

    2002-01-01

    ) and stearic acid (C18H36O2), has been measured at the photon energies 81, 356, 511, 662, 1173 and 1332 keV. Experimental values for the molar extinction coefficient, the effective atomic number and the electron density have been derived and compared with theoretical calculations. There is good agreement......The attenuation of gamma rays in some fatty acids, viz. formic acid (CH2O2), acetic acid (C2H4O2), propionic acid (C3H6O2), butyric acid (C4H8O2), n-hexanoic acid (C6H12O2), n-caprylic acid (C8H16O2), lauric acid (C12H24O2), myristic acid (C14H28O2), palmitic acid (C16H32O2), oleic acid (C18H34O2...

  14. Promotion of cooperation by selective group extinction

    Science.gov (United States)

    Böttcher, Marvin A.; Nagler, Jan

    2016-06-01

    Multilevel selection is an important organizing principle that crucially underlies evolutionary processes from the emergence of cells to eusociality and the economics of nations. Previous studies on multilevel selection assumed that the effective higher-level selection emerges from lower-level reproduction. This leads to selection among groups, although only individuals reproduce. We introduce selective group extinction, where groups die with a probability inversely proportional to their group fitness. When accounting for this the critical benefit-to-cost ratio is substantially lowered. Because in game theory and evolutionary dynamics the degree of cooperation crucially depends on this ratio above which cooperation emerges, previous studies may have substantially underestimated the establishment and maintenance of cooperation.

  15. Is chytridiomycosis driving Darwin's frogs to extinction?

    Directory of Open Access Journals (Sweden)

    Claudio Soto-Azat

    Full Text Available Darwin's frogs (Rhinoderma darwinii and R. rufum are two species of mouth brooding frogs from Chile and Argentina that have experienced marked population declines. Rhinoderma rufum has not been found in the wild since 1980. We investigated historical and current evidence of Batrachochytrium dendrobatidis (Bd infection in Rhinoderma spp. to determine whether chytridiomycosis is implicated in the population declines of these species. Archived and live specimens of Rhinoderma spp., sympatric amphibians and amphibians at sites where Rhinoderma sp. had recently gone extinct were examined for Bd infection using quantitative real-time PCR. Six (0.9% of 662 archived anurans tested positive for Bd (4/289 R. darwinii; 1/266 R. rufum and 1/107 other anurans, all of which had been collected between 1970 and 1978. An overall Bd-infection prevalence of 12.5% was obtained from 797 swabs taken from 369 extant individuals of R. darwinii and 428 individuals representing 18 other species of anurans found at sites with current and recent presence of the two Rhinoderma species. In extant R. darwinii, Bd-infection prevalence (1.9% was significantly lower than that found in other anurans (7.3%. The prevalence of infection (30% in other amphibian species was significantly higher in sites where either Rhinoderma spp. had become extinct or was experiencing severe population declines than in sites where there had been no apparent decline (3.0%; x(2 = 106.407, P<0.001. This is the first report of widespread Bd presence in Chile and our results are consistent with Rhinoderma spp. declines being due to Bd infection, although additional field and laboratory investigations are required to investigate this further.

  16. High frequency of functional extinctions in ecological networks.

    Science.gov (United States)

    Säterberg, Torbjörn; Sellman, Stefan; Ebenman, Bo

    2013-07-25

    Intensified exploitation of natural populations and habitats has led to increased mortality rates and decreased abundances of many species. There is a growing concern that this might cause critical abundance thresholds of species to be crossed, with extinction cascades and state shifts in ecosystems as a consequence. When increased mortality rate and decreased abundance of a given species lead to extinction of other species, this species can be characterized as functionally extinct even though it still exists. Although such functional extinctions have been observed in some ecosystems, their frequency is largely unknown. Here we use a new modelling approach to explore the frequency and pattern of functional extinctions in ecological networks. Specifically, we analytically derive critical abundance thresholds of species by increasing their mortality rates until an extinction occurs in the network. Applying this approach on natural and theoretical food webs, we show that the species most likely to go extinct first is not the one whose mortality rate is increased but instead another species. Indeed, up to 80% of all first extinctions are of another species, suggesting that a species' ecological functionality is often lost before its own existence is threatened. Furthermore, we find that large-bodied species at the top of the food chains can only be exposed to small increases in mortality rate and small decreases in abundance before going functionally extinct compared to small-bodied species lower in the food chains. These results illustrate the potential importance of functional extinctions in ecological networks and lend strong support to arguments advocating a more community-oriented approach in conservation biology, with target levels for populations based on ecological functionality rather than on mere persistence.

  17. Trajectories of Late Permian – Jurassic radiolarian extinction rates: no evidence for an end-Triassic mass extinction

    Directory of Open Access Journals (Sweden)

    W. Kiessling

    2011-02-01

    Full Text Available The hypothesis that ocean acidification was a proximate trigger of the marine end-Triassic mass extinction rests on the assumption that taxa that strongly invest in the secretion of calcium-carbonate skeletons were significantly more affected by the crisis than other taxa. An argument against this hypothesis is the great extinction toll of radiolarians that has been reported from work on local sections. Radiolarians have siliceous tests and thus should be less affected by ocean acidification. We compiled taxonomically vetted occurrences of late Permian and Mesozoic radiolarians and analyzed extinction dynamics of radiolarian genera. Although extinction rates were high at the end of the Triassic, there is no evidence for a mass extinction in radiolarians but rather significantly higher background extinction in the Triassic than in the Jurassic. Although the causes for this decline in background extinction levels remain unclear, the lack of a major evolutionary response to the end-Triassic event, gives support for the hypothesis that ocean acidification was involved in the dramatic extinctions of many calcifying taxa. doi:10.1002/mmng.201000017

  18. Accelerated modern human?induced species losses: Entering the sixth mass extinction

    OpenAIRE

    Ceballos, Gerardo; Ehrlich, Paul R.; Barnosky, Anthony D.; Garc?a, Andr?s; Pringle, Robert M.; Palmer, Todd M.

    2015-01-01

    The oft-repeated claim that Earth?s biota is entering a sixth ?mass extinction? depends on clearly demonstrating that current extinction rates are far above the ?background? rates prevailing between the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we...

  19. Soil stabilization field trial : interim report III.

    Science.gov (United States)

    2003-11-01

    Shrinkage cracks in cement-stabilized bases/subbase can be alleviated by specifying the right cement dosage, or by other additives/procedures that suppress crack susceptibility. A field trial of six 1000 ft test sections to investigate several altern...

  20. Soil stabilization field trial : interim report.

    Science.gov (United States)

    2001-04-01

    Shrinkage cracks in cement-stabilized bases/subbase can be alleviated by specifying : the right cement dosage, or by other additives/procedures that suppress crack susceptibility. A field : trial of six 1000 ft test sections to investigate several al...

  1. Soil stabilization field trial : interim report I.

    Science.gov (United States)

    2001-04-01

    Shrinkage cracks in cement-stabilized bases/subbase can be alleviated by specifying the right cement dosage, or by other additives/procedures that suppress crack susceptibility. A field trial of six 1000 ft test sections to investigate several altern...

  2. Modulation of 7 T fMRI Signal in the Cerebellar Cortex and Nuclei During Acquisition, Extinction, and Reacquisition of Conditioned Eyeblink Responses.

    Science.gov (United States)

    Ernst, Thomas M; Thürling, Markus; Müller, Sarah; Kahl, Fabian; Maderwald, Stefan; Schlamann, Marc; Boele, Henk-Jan; Koekkoek, Sebastiaan K E; Diedrichsen, Jörn; De Zeeuw, Chris I; Ladd, Mark E; Timmann, Dagmar

    2017-08-01

    Classical delay eyeblink conditioning is likely the most commonly used paradigm to study cerebellar learning. As yet, few studies have focused on extinction and savings of conditioned eyeblink responses (CRs). Saving effects, which are reflected in a reacquisition after extinction that is faster than the initial acquisition, suggest that learned associations are at least partly preserved during extinction. In this study, we tested the hypothesis that acquisition-related plasticity is nihilated during extinction in the cerebellar cortex, but retained in the cerebellar nuclei, allowing for faster reacquisition. Changes of 7 T functional magnetic resonance imaging (fMRI) signals were investigated in the cerebellar cortex and nuclei of young and healthy human subjects. Main effects of acquisition, extinction, and reacquisition against rest were calculated in conditioned stimulus-only trials. First-level β values were determined for a spherical region of interest (ROI) around the acquisition peak voxel in lobule VI, and dentate and interposed nuclei ipsilateral to the unconditioned stimulus. In the cerebellar cortex and nuclei, fMRI signals were significantly lower in extinction compared to acquisition and reacquisition, but not significantly different between acquisition and reacquisition. These findings are consistent with the theory of bidirectional learning in both the cerebellar cortex and nuclei. It cannot explain, however, why conditioned responses reappear almost immediately in reacquisition following extinction. Although the present data do not exclude that part of the initial memory remains in the cerebellum in extinction, future studies should also explore changes in extracerebellar regions as a potential substrate of saving effects. Hum Brain Mapp 38:3957-3974, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  3. Study of plutonium fire extinction in glove-boxes; Etude sur l'extinction des feux de plutonium en boites a gants

    Energy Technology Data Exchange (ETDEWEB)

    Boisson, H; Chappellier, A; Debiar, A; Savornin, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    The report concerns attempts to extinguish fire in uranium - chosen as a basis for comparison - and in plutonium, these being contained in glove boxes. The extinguishing powders TEC and MG 10 were tried and compared. The operator used in plastic bags. The metal was dealt with respectively in the form of billets, compact chips and finally thin shavings. In each case fire control was without difficulty. One must allow a certain time for cooling. The powder MG 10 showed very good results. Moreover, the trials proved that densely packed shavings are a very real security factor. The interior lay-out of the glove boxes ought, in order to facilitate further manipulations, be such as to render extinction as easy as possible should the need arise. (authors) [French] II s'agit d'un compte rendu d'essais d'extinction sur feux d'uranium - pris comme base de comparaison - et de plutonium, en boites a gants. Sont utilisees et comparees les poudres extinctrices TEC et MG 10. Elles sont employees par l'operateur en sachets de plastique. Le metal est pris successivement sous forme de billettes, de copeaux compactes, enfin de tournures fines. L'intervention est aisee dans tous les cas; il faut laisser un certain temps de refroidissement. La poudre MG 10 a donne de tres bons resultats, Les essais ont montre, de plus, que le compactage des copeaux est un facteur reel de securite. L'agencement interieur des boites a gants pour les manipulations a venir, devrait tenir compte de cette facilite d'extinction afin de la rendre la plus aisee possible en cas de besoin. (auteurs)

  4. Can we avoid the Sixth Mass Extinction? Setting today's extinction crisis in the context of the Big Five

    Science.gov (United States)

    Barnosky, A. D.

    2012-12-01

    While the ultimate extinction driver now—Homo sapiens—is unique with respect to the drivers of past extinctions, comparison of parallel neontological and paleontological information helps calibrate how far the so-called Sixth Mass Extinction has progressed and whether it is inevitable. Such comparisons document that rates of extinction today are approaching or exceeding those that characterized the Big Five Mass Extinctions. Continuation of present extinction rates for vertebrates, for example, would result in 75% species loss—the minimum benchmark exhibited in the Big Five extinctions—within 3 to 22 centuries, assuming constant rates of loss and no threshold effects. Preceding and during each of the Big Five, the global ecosystem experienced major changes in climate, atmospheric chemisty, and ocean chemistry—not unlike what is being observed presently. Nevertheless, only 1-2% of well-assessed modern species have been lost over the past five centuries, still far below what characterized past mass extinctions in the strict paleontological sense. For mammals, adding in the end-Pleistocene species that died out would increase the species-loss percentage by some 5%. If threatened vertebrate species were to actually go extinct, losses would rise to between 14 and 40%, depending on the group. Such observations highlight that, although many species have already had their populations drastically reduced to near-critical levels, the Sixth Mass Extinction has not yet progressed to the point where it is unavoidable. Put another way, the vast majority of species that have occupied the world in concert with Homo sapiens are still alive and are possible to save. That task, however, will require slowing the abnormally high extinction rates that are now in progress, which in turn requires unified efforts to cap human population growth, decrease the average human footprint, reduce fossil fuel use while simultaneously increasing clean energy technologies, integrate

  5. Tying Extinction Events to Comet Impacts Large Enough to Cause an Extinction in Themselves.

    Science.gov (United States)

    Burgener, J. A.

    2017-12-01

    Comets over 35 km in size impacting Earth will create vast fireballs, and will boil large parts of the oceans, causing extinction events in themselves. They will likely provide enough energy to shatter the crust and eject large masses of molten rock from the mantle, forming traps. Traps are clearly associated with extinction events, but are not expected to cause extinctions. While Chicxulub is recognized to have occurred at the time of the K/Pg boundary layer, it is recognized as being too small in itself to cause an extinction. Are large comet impacts likely? The Kuiper belt has more than 100,000 objects over 100 km in diameter and millions over 10 km. Typically their orbits are less stable than asteroid orbits due to large bodies such as Pluto moving through the belt. The asteroid belt has only 10,000 objects over 10 km diameter. Comet impacts should be more common than asteroid impacts, yet none of the recognized craters are expected to be due to comets. There are many features on Earth that are poorly explained by Plate Tectonics that would be well explained if they were considered to be comet impact craters. A consideration of the Black Sea and the Tarim Basin will show that impact interpretations are a better fit than the present Plate Tectonics' explanations. Both basins are in the midst of mountain building from plate collisions, but are themselves not being disturbed by the plate collisions. Both are ellipses angled at 23.4 degrees to the equator, matching the angle expected for a low angle impact from a comet traveling in the ecliptic. Both are too deep at 15 km depths to be standard oceans (typically 5 km deep). Both are filled with horizontal layers of sediments, undisturbed by the mountain building occurring at the edges. Both have thin crusts and high Moho boundaries. Both have thin lithosphere. Yet both show GPS movement of the land around them moving away from them, as though they were much thicker and stronger than the surrounding land. The Tarim

  6. Size distribution of interstellar particles. III. Peculiar extinctions and normal infrared extinction

    International Nuclear Information System (INIS)

    Mathis, J.S.; Wallenhorst, S.G.

    1981-01-01

    The effect of changing the upper and lower size limits of a distribution of bare graphite and silicate particles with n(a)αa/sup -q/ is investigated. Mathis, Rumpl, and Nordsieck showed that the normal extinction is matched very well by having the small-size cutoff, a/sub -/, roughly-equal0.005 or 0.01 μm, and the large size a/sub +/, about 0.25 μm, and q = 3.5 for both substances. We consider the progressively peculiar extinctions exhibited by the well-observed stars, sigma Sco, rho Oph, and theta 1 Ori C, with values of R/sub v/[equivalentA/sub v//E(B--V)] of 3.4, 4.4, and 5.5 compared to the normal 3.1. Two (sigma Sco, rho Oph) are in a neutral dense cloud; theta 1 Ori C is in the Orion Nebula. We find that sigma Sco has a normal graphite distribution but has had its small silicate particles removed, so that a/sub -/(sil)roughly-equal0.04 μm if q = 3.5, or q(sil) = 2.6 if the size limits are fixed. However, the upper size limit on silicates remains normal. In rho Oph, the graphite is still normal, but both a/sub -/(sil) and a/sub +/(sil) are increased, to about 0.04 μm and 0.4 or 0.5 μm, respectively, if q = 3.5, or q(sil)roughly-equal1.3 if the size limits are fixed. In theta 1 Ori, the small limit on graphite has increased to about 0.04 μm, or q(gra)roughly-equal3, while the silicates are about like those in rho Oph. The calculated lambda2175 bump is broader than the observed, but normal foreground extinction probably contributes appreciably to the observed bump. The absolute amount of extinction per H atom for rho Oph is not explained. The column density of H is so large that systematic effects might be present. Very large graphite particles (a>3 μm) are required to ''hide'' the graphite without overly affecting the visual extinction, but a normal (small) graphite size distribution is required by the lambda2175 bump. We feel that it is unlikely that such a bimodal distribution exists

  7. Juvenile female rats, but not male rats, show renewal, reinstatement, and spontaneous recovery following extinction of conditioned fear.

    Science.gov (United States)

    Park, Chun Hui J; Ganella, Despina E; Kim, Jee Hyun

    2017-12-01

    Anxiety disorders emerge early, and girls are significantly more likely to develop anxiety compared to boys. However, sex differences in fear during development are poorly understood. Therefore, we investigated juvenile male and female rats in the relapse behaviors following extinction of conditioned fear. In all experiments, 18-d-old rats first received three white-noise-footshock pairings on day 1. On day 2, extinction involved 60 white-noise alone trials. In experiment 1, we examined renewal by testing the rats in either the same or different context as extinction on day 3. Male rats did not show renewal, however, female rats showed renewal. Experiment 2 investigated reinstatement by giving rats either a mild reminder footshock or context exposure on day 3. When tested the next day, male rats did not show reinstatement, whereas female rats showed reinstatement. Experiment 3 investigated spontaneous recovery by testing the rats either 1 or 5 d following extinction. Male rats did not show any spontaneous recovery whereas female rats did. Taken together, fear regulation appear to be different in males versus females from early in development, which may explain why girls are more prone to suffer from anxiety disorders compared to boys. © 2017 Park et al.; Published by Cold Spring Harbor Laboratory Press.

  8. Learning and extinction of conditioned hearing sensation change in the beluga whale (Delphinapterus leucas).

    Science.gov (United States)

    Nachtigall, Paul E; Supin, Alexander Ya; Estaban, Jose-Antonio; Pacini, Aude F

    2016-02-01

    Ice-dwelling beluga whales are increasingly being exposed to anthropogenic loud sounds. Beluga's hearing sensitivity measured during a warning sound just preceding a loud sound was tested using pip-train stimuli and auditory evoked potential recording. When the test/warning stimulus with a frequency of 32 or 45 kHz preceded the loud sound with a frequency of 32 kHz and a sound pressure level of 153 dB re 1 μPa, 2 s, hearing thresholds before the loud sound increased relative to the baseline. The threshold increased up to 15 dB for the test frequency of 45 kHz and up to 13 dB for the test frequency of 32 kHz. These threshold increases were observed during two sessions of 36 trials each. Extinction tests revealed no change during three experimental sessions followed by a jump-like return to baseline thresholds. The low exposure level producing the hearing-dampening effect (156 dB re 1 µPa(2)s in each trial), and the manner of extinction, may be considered as evidence that the observed hearing threshold increases were a demonstration of conditioned dampening of hearing when the whale anticipated the quick appearance of a loud sound in the same way demonstrated in the false killer whale and bottlenose dolphin.

  9. ON GALACTIC DENSITY MODELING IN THE PRESENCE OF DUST EXTINCTION

    International Nuclear Information System (INIS)

    Bovy, Jo; Rix, Hans-Walter; Schlafly, Edward F.; Green, Gregory M.; Finkbeiner, Douglas P.

    2016-01-01

    Inferences about the spatial density or phase-space structure of stellar populations in the Milky Way require a precise determination of the effective survey volume. The volume observed by surveys such as Gaia or near-infrared spectroscopic surveys, which have good coverage of the Galactic midplane region, is highly complex because of the abundant small-scale structure in the three-dimensional interstellar dust extinction. We introduce a novel framework for analyzing the importance of small-scale structure in the extinction. This formalism demonstrates that the spatially complex effect of extinction on the selection function of a pencil-beam or contiguous sky survey is equivalent to a low-pass filtering of the extinction-affected selection function with the smooth density field. We find that the angular resolution of current 3D extinction maps is sufficient for analyzing Gaia sub-samples of millions of stars. However, the current distance resolution is inadequate and needs to be improved by an order of magnitude, especially in the inner Galaxy. We also present a practical and efficient method for properly taking the effect of extinction into account in analyses of Galactic structure through an effective selection function. We illustrate its use with the selection function of red-clump stars in APOGEE using and comparing a variety of current 3D extinction maps

  10. Empirical relationship of ultraviolet extinction and the interstellar diffuse bands

    International Nuclear Information System (INIS)

    Wu, C.; York, D.G.; Snow, T.P.

    1981-01-01

    New ultraviolet colors are presented for 110 hot stars. These data are combined with infrared colors and diffuse-band measurements to study the relationship of diffuse interstellar bands (lambdalambda4430, 5780, 6284) to the overall extinction curve. Equivalent widths of lambdalambda5780 and 6284 are not well correlated with infrared, visible, or ultraviolet extinction measurements for stars in our sample. The central depth of lambda4430 is well correlated with visible and infrared extinction, but less well correlated with UV extinction at 1800 A. lambda4430 is strongly correlated with the strength of the 2200-A bump. Our data suggest that if small grains account for the general rise in UV extinction, the diffuse bands are not formed in these grains. lambda4430 may well arise in large grains and/or in the material responsible for the 2200-A bump. Correlations with UV extinctions derived by other authors are discussed in detail. It is suggested that definitions of extinction parameters and band shapes, as well as selection effects in small samples of stars, may still compromise conclusions based on correlation studies such as we are attempting

  11. LINE DERIVED INFRARED EXTINCTION TOWARD THE GALACTIC CENTER

    International Nuclear Information System (INIS)

    Fritz, T. K.; Gillessen, S.; Dodds-Eden, K.; Lutz, D.; Genzel, R.; Raab, W.; Ott, T.; Pfuhl, O.; Eisenhauer, F.; Yusef-Zadeh, F.

    2011-01-01

    We derive the extinction curve toward the Galactic center (GC) from 1 to 19 μm. We use hydrogen emission lines of the minispiral observed by ISO-SWS and SINFONI. The extinction-free flux reference is the 2 cm continuum emission observed by the Very Large Array. Toward the inner 14'' x 20'', we find an extinction of A 2.166μm = 2.62 ± 0.11, with a power-law slope of α = -2.11 ± 0.06 shortward of 2.8 μm, consistent with the average near-infrared slope from the recent literature. At longer wavelengths, however, we find that the extinction is grayer than shortward of 2.8 μm. We find that it is not possible to fit the observed extinction curve with a dust model consisting of pure carbonaceous and silicate grains only, and the addition of composite particles, including ices, is needed to explain the observations. Combining a distance-dependent extinction with our distance-independent extinction, we derive the distance to the GC to be R 0 = 7.94 ± 0.65 kpc. Toward Sgr A* (r H = 4.21 ± 0.10, A Ks = 2.42 ± 0.10, and A L' = 1.09 ± 0.13.

  12. ON GALACTIC DENSITY MODELING IN THE PRESENCE OF DUST EXTINCTION

    Energy Technology Data Exchange (ETDEWEB)

    Bovy, Jo [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON, M5S 3H4 (Canada); Rix, Hans-Walter; Schlafly, Edward F. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Green, Gregory M.; Finkbeiner, Douglas P., E-mail: bovy@astro.utoronto.ca [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2016-02-20

    Inferences about the spatial density or phase-space structure of stellar populations in the Milky Way require a precise determination of the effective survey volume. The volume observed by surveys such as Gaia or near-infrared spectroscopic surveys, which have good coverage of the Galactic midplane region, is highly complex because of the abundant small-scale structure in the three-dimensional interstellar dust extinction. We introduce a novel framework for analyzing the importance of small-scale structure in the extinction. This formalism demonstrates that the spatially complex effect of extinction on the selection function of a pencil-beam or contiguous sky survey is equivalent to a low-pass filtering of the extinction-affected selection function with the smooth density field. We find that the angular resolution of current 3D extinction maps is sufficient for analyzing Gaia sub-samples of millions of stars. However, the current distance resolution is inadequate and needs to be improved by an order of magnitude, especially in the inner Galaxy. We also present a practical and efficient method for properly taking the effect of extinction into account in analyses of Galactic structure through an effective selection function. We illustrate its use with the selection function of red-clump stars in APOGEE using and comparing a variety of current 3D extinction maps.

  13. MODELING GALACTIC EXTINCTION WITH DUST AND 'REAL' POLYCYCLIC AROMATIC HYDROCARBONS

    International Nuclear Information System (INIS)

    Mulas, Giacomo; Casu, Silvia; Cecchi-Pestellini, Cesare; Zonca, Alberto

    2013-01-01

    We investigate the remarkable apparent variety of galactic extinction curves by modeling extinction profiles with core-mantle grains and a collection of single polycyclic aromatic hydrocarbons. Our aim is to translate a synthetic description of dust into physically well-grounded building blocks through the analysis of a statistically relevant sample of different extinction curves. All different flavors of observed extinction curves, ranging from the average galactic extinction curve to virtually 'bumpless' profiles, can be described by the present model. We prove that a mixture of a relatively small number (54 species in 4 charge states each) of polycyclic aromatic hydrocarbons can reproduce the features of the extinction curve in the ultraviolet, dismissing an old objection to the contribution of polycyclic aromatic hydrocarbons to the interstellar extinction curve. Despite the large number of free parameters (at most the 54 × 4 column densities of each species in each ionization state included in the molecular ensemble plus the 9 parameters defining the physical properties of classical particles), we can strongly constrain some physically relevant properties such as the total number of C atoms in all species and the mean charge of the mixture. Such properties are found to be largely independent of the adopted dust model whose variation provides effects that are orthogonal to those brought about by the molecular component. Finally, the fitting procedure, together with some physical sense, suggests (but does not require) the presence of an additional component of chemically different very small carbonaceous grains.

  14. Sexual selection affects local extinction and turnover in bird communities

    Science.gov (United States)

    Doherty, P.F.; Sorci, G.; Royle, J. Andrew; Hines, J.E.; Nichols, J.D.; Boulinier, T.

    2003-01-01

    Predicting extinction risks has become a central goal for conservation and evolutionary biologists interested in population and community dynamics. Several factors have been put forward to explain risks of extinction, including ecological and life history characteristics of individuals. For instance, factors that affect the balance between natality and mortality can have profound effects on population persistence. Sexual selection has been identified as one such factor. Populations under strong sexual selection experience a number of costs ranging from increased predation and parasitism to enhanced sensitivity to environmental and demographic stochasticity. These findings have led to the prediction that local extinction rates should be higher for species/populations with intense sexual selection. We tested this prediction by analyzing the dynamics of natural bird communities at a continental scale over a period of 21 years (1975-1996), using relevant statistical tools. In agreement with the theoretical prediction, we found that sexual selection increased risks of local extinction (dichromatic birds had on average a 23% higher local extinction rate than monochromatic species). However, despite higher local extinction probabilities, the number of dichromatic species did not decrease over the period considered in this study. This pattern was caused by higher local turnover rates of dichromatic species, resulting in relatively stable communities for both groups of species. Our results suggest that these communities function as metacommunities, with frequent local extinctions followed by colonization. Anthropogenic factors impeding dispersal might therefore have a significant impact on the global persistence of sexually selected species.

  15. Dietary Modulation of Gut Microbiota Contributes to Alleviation of Both Genetic and Simple Obesity in Children.

    Science.gov (United States)

    Zhang, Chenhong; Yin, Aihua; Li, Hongde; Wang, Ruirui; Wu, Guojun; Shen, Jian; Zhang, Menghui; Wang, Linghua; Hou, Yaping; Ouyang, Haimei; Zhang, Yan; Zheng, Yinan; Wang, Jicheng; Lv, Xiaofei; Wang, Yulan; Zhang, Feng; Zeng, Benhua; Li, Wenxia; Yan, Feiyan; Zhao, Yufeng; Pang, Xiaoyan; Zhang, Xiaojun; Fu, Huaqing; Chen, Feng; Zhao, Naisi; Hamaker, Bruce R; Bridgewater, Laura C; Weinkove, David; Clement, Karine; Dore, Joel; Holmes, Elaine; Xiao, Huasheng; Zhao, Guoping; Yang, Shengli; Bork, Peer; Nicholson, Jeremy K; Wei, Hong; Tang, Huiru; Zhang, Xiaozhuang; Zhao, Liping

    2015-08-01

    Gut microbiota has been implicated as a pivotal contributing factor in diet-related obesity; however, its role in development of disease phenotypes in human genetic obesity such as Prader-Willi syndrome (PWS) remains elusive. In this hospitalized intervention trial with PWS (n = 17) and simple obesity (n = 21) children, a diet rich in non-digestible carbohydrates induced significant weight loss and concomitant structural changes of the gut microbiota together with reduction of serum antigen load and alleviation of inflammation. Co-abundance network analysis of 161 prevalent bacterial draft genomes assembled directly from metagenomic datasets showed relative increase of functional genome groups for acetate production from carbohydrates fermentation. NMR-based metabolomic profiling of urine showed diet-induced overall changes of host metabotypes and identified significantly reduced trimethylamine N-oxide and indoxyl sulfate, host-bacteria co-metabolites known to induce metabolic deteriorations. Specific bacterial genomes that were correlated with urine levels of these detrimental co-metabolites were found to encode enzyme genes for production of their precursors by fermentation of choline or tryptophan in the gut. When transplanted into germ-free mice, the pre-intervention gut microbiota induced higher inflammation and larger adipocytes compared with the post-intervention microbiota from the same volunteer. Our multi-omics-based systems analysis indicates a significant etiological contribution of dysbiotic gut microbiota to both genetic and simple obesity in children, implicating a potentially effective target for alleviation. Poorly managed diet and genetic mutations are the two primary driving forces behind the devastating epidemic of obesity-related diseases. Lack of understanding of the molecular chain of causation between the driving forces and the disease endpoints retards progress in prevention and treatment of the diseases. We found that children

  16. Dietary Modulation of Gut Microbiota Contributes to Alleviation of Both Genetic and Simple Obesity in Children☆

    Science.gov (United States)

    Zhang, Chenhong; Yin, Aihua; Li, Hongde; Wang, Ruirui; Wu, Guojun; Shen, Jian; Zhang, Menghui; Wang, Linghua; Hou, Yaping; Ouyang, Haimei; Zhang, Yan; Zheng, Yinan; Wang, Jicheng; Lv, Xiaofei; Wang, Yulan; Zhang, Feng; Zeng, Benhua; Li, Wenxia; Yan, Feiyan; Zhao, Yufeng; Pang, Xiaoyan; Zhang, Xiaojun; Fu, Huaqing; Chen, Feng; Zhao, Naisi; Hamaker, Bruce R.; Bridgewater, Laura C.; Weinkove, David; Clement, Karine; Dore, Joel; Holmes, Elaine; Xiao, Huasheng; Zhao, Guoping; Yang, Shengli; Bork, Peer; Nicholson, Jeremy K.; Wei, Hong; Tang, Huiru; Zhang, Xiaozhuang; Zhao, Liping

    2015-01-01

    Gut microbiota has been implicated as a pivotal contributing factor in diet-related obesity; however, its role in development of disease phenotypes in human genetic obesity such as Prader–Willi syndrome (PWS) remains elusive. In this hospitalized intervention trial with PWS (n = 17) and simple obesity (n = 21) children, a diet rich in non-digestible carbohydrates induced significant weight loss and concomitant structural changes of the gut microbiota together with reduction of serum antigen load and alleviation of inflammation. Co-abundance network analysis of 161 prevalent bacterial draft genomes assembled directly from metagenomic datasets showed relative increase of functional genome groups for acetate production from carbohydrates fermentation. NMR-based metabolomic profiling of urine showed diet-induced overall changes of host metabotypes and identified significantly reduced trimethylamine N-oxide and indoxyl sulfate, host-bacteria co-metabolites known to induce metabolic deteriorations. Specific bacterial genomes that were correlated with urine levels of these detrimental co-metabolites were found to encode enzyme genes for production of their precursors by fermentation of choline or tryptophan in the gut. When transplanted into germ-free mice, the pre-intervention gut microbiota induced higher inflammation and larger adipocytes compared with the post-intervention microbiota from the same volunteer. Our multi-omics-based systems analysis indicates a significant etiological contribution of dysbiotic gut microbiota to both genetic and simple obesity in children, implicating a potentially effective target for alleviation. Research in context Poorly managed diet and genetic mutations are the two primary driving forces behind the devastating epidemic of obesity-related diseases. Lack of understanding of the molecular chain of causation between the driving forces and the disease endpoints retards progress in prevention and treatment of the diseases. We found

  17. Massage Alleviates Delayed Onset Muscle Soreness after Strenuous Exercise: A Systematic Review and Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Jianmin Guo

    2017-09-01

    Full Text Available Purpose: The purpose of this systematic review and meta-analysis was to evaluate the effects of massage on alleviating delayed onset of muscle soreness (DOMS and muscle performance after strenuous exercise.Method: Seven databases consisting of PubMed, Embase, EBSCO, Cochrane Library, Web of Science, CNKI and Wanfang were searched up to December 2016. Randomized controlled trials (RCTs were eligible and the outcomes of muscle soreness, performance (including muscle maximal isometric force (MIF and peak torque and creatine kinase (CK were used to assess the effectiveness of massage intervention on DOMS.Results: Eleven articles with a total of 23 data points (involving 504 participants satisfied the inclusion criteria and were pooled in the meta-analysis. The findings demonstrated that muscle soreness rating decreased significantly when the participants received massage intervention compared with no intervention at 24 h (SMD: –0.61, 95% CI: –1.17 to –0.05, P = 0.03, 48 h (SMD: –1.51, 95% CI: –2.24 to –0.77, P < 0.001, 72 h (SMD: –1.46, 95% CI: –2.59 to –0.33, P = 0.01 and in total (SMD: –1.16, 95% CI: –1.60 to –0.72, P < 0.001 after intense exercise. Additionally, massage therapy improved MIF (SMD: 0.56, 95% CI: 0.21–0.90, P = 0.002 and peak torque (SMD: 0.38, 95% CI: 0.04–0.71, P = 0.03 as total effects. Furthermore, the serum CK level was reduced when participants received massage intervention (SMD: –0.64, 95% CI: –1.04 to –0.25, P = 0.001.Conclusion: The current evidence suggests that massage therapy after strenuous exercise could be effective for alleviating DOMS and improving muscle performance.

  18. Relationship of extinction to perceptual thresholds for single stimuli.

    Science.gov (United States)

    Meador, K J; Ray, P G; Day, L J; Loring, D W

    2001-04-24

    To demonstrate the effects of target stimulus intensity on extinction to double simultaneous stimuli. Attentional deficits contribute to extinction in patients with brain lesions, but extinction (i.e., masking) can also be produced in healthy subjects. The relationship of extinction to perceptual thresholds for single stimuli remains uncertain. Brief electrical pulses were applied simultaneously to the left and right index fingers of 16 healthy volunteers (8 young and 8 elderly adults) and 4 patients with right brain stroke (RBS). The stimulus to be perceived (i.e., target stimulus) was given at the lowest perceptual threshold to perceive any single stimulus (i.e., Minimal) and at the threshold to perceive 100% of single stimuli. The mask stimulus (i.e., stimulus given to block the target) was applied to the contralateral hand at intensities just below discomfort. Extinction was less for target stimuli at 100% than Minimal threshold for healthy subjects. Extinction of left targets was greater in patients with RBS than elderly control subjects. Left targets were extinguished less than right in healthy subjects. In contrast, the majority of left targets were extinguished in patients with RBS even when right mask intensity was reduced below right 100% threshold for single stimuli. RBS patients had less extinction for right targets despite having greater left mask - threshold difference than control subjects. In patients with RBS, right "targets" at 100% threshold extinguished left "masks" (20%) almost as frequently as left masks extinguished right targets (32%). Subtle changes in target intensity affect extinction in healthy adults. Asymmetries in mask and target intensities (relative to single-stimulus perceptual thresholds) affect extinction in RBS patients less for left targets but more for right targets as compared with control subjects.

  19. Geography of current and future global mammal extinction risk.

    Directory of Open Access Journals (Sweden)

    Ana D Davidson

    Full Text Available Identifying which species are at greatest risk, what makes them vulnerable, and where they are distributed are central goals for conservation science. While knowledge of which factors influence extinction risk is increasingly available for some taxonomic groups, a deeper understanding of extinction correlates and the geography of risk remains lacking. Here, we develop a predictive random forest model using both geospatial and mammalian species' trait data to uncover the statistical and geographic distributions of extinction correlates. We also explore how this geography of risk may change under a rapidly warming climate. We found distinctive macroecological relationships between species-level risk and extinction correlates, including the intrinsic biological traits of geographic range size, body size and taxonomy, and extrinsic geographic settings such as seasonality, habitat type, land use and human population density. Each extinction correlate exhibited ranges of values that were especially associated with risk, and the importance of different risk factors was not geographically uniform across the globe. We also found that about 10% of mammals not currently recognized as at-risk have biological traits and occur in environments that predispose them towards extinction. Southeast Asia had the most actually and potentially threatened species, underscoring the urgent need for conservation in this region. Additionally, nearly 40% of currently threatened species were predicted to experience rapid climate change at 0.5 km/year or more. Biological and environmental correlates of mammalian extinction risk exhibit distinct statistical and geographic distributions. These results provide insight into species-level patterns and processes underlying geographic variation in extinction risk. They also offer guidance for future conservation research focused on specific geographic regions, or evaluating the degree to which species-level patterns mirror spatial

  20. d-Cycloserine reduces context specificity of sexual extinction learning.

    Science.gov (United States)

    Brom, Mirte; Laan, Ellen; Everaerd, Walter; Spinhoven, Philip; Trimbos, Baptist; Both, Stephanie

    2015-11-01

    d-Cycloserine (DCS) enhances extinction processes in animals. Although classical conditioning is hypothesized to play a pivotal role in the aetiology of appetitive motivation problems, no research has been conducted on the effect of DCS on the reduction of context specificity of extinction in human appetitive learning, while facilitation hereof is relevant in the context of treatment of problematic reward-seeking behaviors. Female participants were presented with two conditioned stimuli (CSs) that either predicted (CS+) or did not predict (CS-) a potential sexual reward (unconditioned stimulus (US); genital vibrostimulation). Conditioning took place in context A and extinction in context B. Subjects received DCS (125mg) or placebo directly after the experiment on day 1 in a randomized, double-blind, between-subject fashion (Placebo n=31; DCS n=31). Subsequent testing for CS-evoked conditioned responses (CRs) in both the conditioning (A) and the extinction context (B) took place 24h later on day 2. Drug effects on consolidation were then assessed by comparing the recall of sexual extinction memories between the DCS and the placebo groups. Post learning administration of DCS facilitates sexual extinction memory consolidation and affects extinction's fundamental context specificity, evidenced by reduced conditioned genital and subjective sexual responses, relative to placebo, for presentations of the reward predicting cue 24h later outside the extinction context. DCS makes appetitive extinction memories context-independent and prevents the return of conditioned response. NMDA receptor glycine site agonists may be potential pharmacotherapies for the prevention of relapse of appetitive motivation disorders with a learned component. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Geography of current and future global mammal extinction risk.

    Science.gov (United States)

    Davidson, Ana D; Shoemaker, Kevin T; Weinstein, Ben; Costa, Gabriel C; Brooks, Thomas M; Ceballos, Gerardo; Radeloff, Volker C; Rondinini, Carlo; Graham, Catherine H

    2017-01-01

    Identifying which species are at greatest risk, what makes them vulnerable, and where they are distributed are central goals for conservation science. While knowledge of which factors influence extinction risk is increasingly available for some taxonomic groups, a deeper understanding of extinction correlates and the geography of risk remains lacking. Here, we develop a predictive random forest model using both geospatial and mammalian species' trait data to uncover the statistical and geographic distributions of extinction correlates. We also explore how this geography of risk may change under a rapidly warming climate. We found distinctive macroecological relationships between species-level risk and extinction correlates, including the intrinsic biological traits of geographic range size, body size and taxonomy, and extrinsic geographic settings such as seasonality, habitat type, land use and human population density. Each extinction correlate exhibited ranges of values that were especially associated with risk, and the importance of different risk factors was not geographically uniform across the globe. We also found that about 10% of mammals not currently recognized as at-risk have biological traits and occur in environments that predispose them towards extinction. Southeast Asia had the most actually and potentially threatened species, underscoring the urgent need for conservation in this region. Additionally, nearly 40% of currently threatened species were predicted to experience rapid climate change at 0.5 km/year or more. Biological and environmental correlates of mammalian extinction risk exhibit distinct statistical and geographic distributions. These results provide insight into species-level patterns and processes underlying geographic variation in extinction risk. They also offer guidance for future conservation research focused on specific geographic regions, or evaluating the degree to which species-level patterns mirror spatial variation in the

  2. Semiconductor plasmonic crystals: active control of THz extinction

    International Nuclear Information System (INIS)

    Schaafsma, M C; Rivas, J Gómez

    2013-01-01

    We investigate theoretically the enhanced THz extinction by periodic arrays of semiconductor particles. Scattering particles of doped semiconductors can sustain localized surface plasmon polaritons, which can be diffractively coupled giving rise to surface lattice resonances. These resonances are characterized by a large extinction and narrow bandwidth, which can be tuned by controlling the charge carrier density in the semiconductor. The underlaying mechanism leading to this tuneability is explained using the coupled dipole approximation and considering GaAs as the semiconductor. The enhanced THz extinction in arrays of GaAs particles could be tuned in a wide range by optical pumping of charge carriers. (invited article)

  3. Extinction in finite perfect crystals: Case of a sphere

    International Nuclear Information System (INIS)

    Al Haddad, M.; Becker, P.

    1990-01-01

    The extinction factor in finite perfect crystals is calculated from pure dynamical theory. In particular, a detailed solution is proposed for a sphere, in which case the extinction factor depends on the Bragg angle θ and the parameter (R/Λ), where R is the radius of the crystal and Λ the extinction length. An approximate solution based on the Laue geometry is proposed and corrections to take care of the complex boundary conditions are presented. An expression easily usable in refinement programs is proposed that fits the exact value to better than 1%. (orig.)

  4. Extinction partially reverts structural changes associated with remote fear memory

    DEFF Research Database (Denmark)

    Vetere, Gisella; Restivo, Leonardo; Novembre, Giovanni

    2011-01-01

    Structural synaptic changes occur in medial prefrontal cortex circuits during remote memory formation. Whether extinction reverts or further reshapes these circuits is, however, unknown. Here we show that the number and the size of spines were enhanced in anterior cingulate (aCC) and infralimbic...... (ILC) cortices 36 d following contextual fear conditioning. Upon extinction, aCC spine density returned to baseline, but the enhanced proportion of large spines did not. Differently, ILC spine density remained elevated, but the size of spines decreased dramatically. Thus, extinction partially erases...

  5. Variations in ultraviolet extinction: effect of polarization revisited

    International Nuclear Information System (INIS)

    Greenberg, J.M.; Chlewicki, G.; Rijksuniversiteit Groningen

    1987-01-01

    The alignment of the particles responsible for the polarization and visual extinction is shown to provide a basis for changing the saturation level of the ultraviolet extinction without changing the particle sizes. If the particles are well aligned, it is predicted that there should be significantly lower extinction in the ultraviolet relative to the visible for stars viewed perpendicular to magnetic-field lines (maximum polarization) as compared with those viewed across the field lines. Preliminary evidence for such an effect is noted in Carina. (author)

  6. High extinction ratio integrated optical modulator for quantum telecommunication systems

    Science.gov (United States)

    Tronev, A.; Parfenov, M.; Agruzov, P.; Ilichev, I.; Shamray, A.

    2018-01-01

    A method for increasing the extinction ratio of integrated optical Mach-Zehnder modulators based on LiNbO3 via the photorefractive effect is proposed. The influence of the photorefractive effect on the X- and Y-splitters of intensity modulators is experimentally studied. An increase in the modulator extinction ratio by 17 dB (from 30 to 47 dB) is obtained. It is shown that fabricated modulators with a high extinction ratio are important for quantum key distribution systems.

  7. The use of extinction corrections in neutron diffraction experiments

    International Nuclear Information System (INIS)

    Delapalme, A.

    1987-08-01

    Extinction can be treated through various models originating in either kinematical (intensity coupling) or dynamical (wave coupling) theories. For most crystals the situation is intermediate between these two extreme cases and extinction models are necessary to obtain precise Fourier components (structure factors) and the electronic and magnetic distribution in molecules and crystals. New models reveal new parameters and new effects of their role in the Extinction phenomena, but the phenomenological aspect of the solutions shows the difficulty to describe adequately what happens in real crystals

  8. Characterization of Diesel Soot Aggregates by Scattering and Extinction Methods

    Science.gov (United States)

    Kamimoto, Takeyuki

    2006-07-01

    Characteristics of diesel soot particles sampled from diesel exhaust of a common-rail turbo-charged diesel engine are quantified by scattering and extinction diagnostics using newly build two laser-based instruments. The radius of gyration representing the aggregates size is measured by the angular distribution of scattering intensity, while the soot mass concentration is measured by a two-wavelength extinction method. An approach to estimate the refractive index of diesel soot by an analysis of the extinction and scattering data using an aggregates scattering theory is proposed.

  9. Characterization of Diesel Soot Aggregates by Scattering and Extinction Methods

    International Nuclear Information System (INIS)

    Kamimoto, Takeyuki

    2006-01-01

    Characteristics of diesel soot particles sampled from diesel exhaust of a common-rail turbo-charged diesel engine are quantified by scattering and extinction diagnostics using newly build two laser-based instruments. The radius of gyration representing the aggregates size is measured by the angular distribution of scattering intensity, while the soot mass concentration is measured by a two-wavelength extinction method. An approach to estimate the refractive index of diesel soot by an analysis of the extinction and scattering data using an aggregates scattering theory is proposed

  10. Two lines of sight with exceedingly anomalous ultraviolet interstellar extinction

    International Nuclear Information System (INIS)

    Cardelli, J.A.; Savage, B.D.

    1988-01-01

    Low-resolution IUE data toward HD 62542 reveal an extinction curve with an extremely broad and weak UV extinction bump and the highest FUV extinction yet observed in the Milky Way. Parameters describing the central position and FWHM for weak bumps observed toward HD 62542 and HD 29647 are derived using analytical fitting techniques. In both cases, the bump central positions are shifted shortward of 2175 A with an initial wavelength of 2110 A for HD 62542 and an initial wavelength of 2128 A for HD 29647. The bump FWHM is found to be 1.29/micron and 1.62/micron for HD 62542 and HD 29647, respectively. 75 references

  11. Parallel Mitogenome Sequencing Alleviates Random Rooting Effect in Phylogeography.

    Science.gov (United States)

    Hirase, Shotaro; Takeshima, Hirohiko; Nishida, Mutsumi; Iwasaki, Wataru

    2016-04-28

    Reliably rooted phylogenetic trees play irreplaceable roles in clarifying diversification in the patterns of species and populations. However, such trees are often unavailable in phylogeographic studies, particularly when the focus is on rapidly expanded populations that exhibit star-like trees. A fundamental bottleneck is known as the random rooting effect, where a distant outgroup tends to root an unrooted tree "randomly." We investigated whether parallel mitochondrial genome (mitogenome) sequencing alleviates this effect in phylogeography using a case study on the Sea of Japan lineage of the intertidal goby Chaenogobius annularis Eighty-three C. annularis individuals were collected and their mitogenomes were determined by high-throughput and low-cost parallel sequencing. Phylogenetic analysis of these mitogenome sequences was conducted to root the Sea of Japan lineage, which has a star-like phylogeny and had not been reliably rooted. The topologies of the bootstrap trees were investigated to determine whether the use of mitogenomes alleviated the random rooting effect. The mitogenome data successfully rooted the Sea of Japan lineage by alleviating the effect, which hindered phylogenetic analysis that used specific gene sequences. The reliable rooting of the lineage led to the discovery of a novel, northern lineage that expanded during an interglacial period with high bootstrap support. Furthermore, the finding of this lineage suggested the existence of additional glacial refugia and provided a new recent calibration point that revised the divergence time estimation between the Sea of Japan and Pacific Ocean lineages. This study illustrates the effectiveness of parallel mitogenome sequencing for solving the random rooting problem in phylogeographic studies. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  12. Methylphenidate alleviates manganese-induced impulsivity but not distractibility

    Science.gov (United States)

    Beaudin, Stephane A.; Strupp, Barbara J.; Uribe, Walter; Ysais, Lauren; Strawderman, Myla; Smith, Donald R.

    2017-01-01

    Recent studies from our lab have demonstrated that postnatal manganese (Mn) exposure in a rodent model can cause lasting impairments in fine motor control and attention, and that oral methylphenidate (MPH) treatment can effectively treat the dysfunction in fine motor control. However, it is unknown whether MPH treatment can alleviate the impairments in attention produced by Mn exposure. Here we used a rodent model of postnatal Mn exposure to determine whether (1) oral MPH alleviates attention and impulse control deficits caused by postnatal Mn exposure, using attention tasks that are variants of the 5-choice serial reaction time task, and (2) whether these treatments affected neuronal dendritic spine density in the medial prefrontal cortex (mPFC) and dorsal striatum. Male Long-Evans rats were exposed orally to 0 or 50 mg Mn/kg/d throughout life starting on PND 1, and tested as young adults (PND 107 – 115) on an attention task that specifically tapped selective attention and impulse control. Animals were treated with oral MPH (2.5 mg/kg/d) throughout testing on the attention task. Our findings show that lifelong postnatal Mn exposure impaired impulse control and selective attention in young adulthood, and that a therapeutically relevant oral MPH regimen alleviated the Mn-induced dysfunction in impulse control, but not selective attention, and actually impaired focused attention in the Mn group. In addition, the effect of MPH was qualitatively different for the Mn-exposed versus control animals across a range of behavioral measures of inhibitory control and attention, as well as dendritic spine density in the mPFC, suggesting that postnatal Mn exposure alters catecholaminergic systems modulating these behaviors. Collectively these findings suggest that MPH may hold promise for treating the behavioral dysfunction caused by developmental Mn exposure, although further research is needed with multiple MPH doses to determine whether a dose can be identified that

  13. Nephrogenic systemic fibrosis symptoms alleviated by renal transplantation

    DEFF Research Database (Denmark)

    Hansen, Jesper Melchior

    2011-01-01

    are limited. Anecdotal reports have shown partial or complete resolution of NSF following successful renal transplantation early in the course of NSF. In this report, we describe alleviation of NSF symptoms in two women following successful renal transplantation more than 3 years after onset of NSF.......Nephrogenic systemic fibrosis (NSF) is a rare, serious, and life-threatening disease of patients with severe renal impairment. Gadolinium-containing contrast agents have been shown to be the crucial trigger. There is no proven medical cure for the disease, and symptomatic treatment options...

  14. Clinical Trials

    Medline Plus

    Full Text Available ... Clinical Trials About Clinical Trials Clinical trials are research studies that explore whether a medical strategy, treatment, or ... humans. What Are Clinical Trials? Clinical trials are research studies that explore whether a medical strategy, treatment, or ...

  15. Noradrenergic stimulation modulates activation of extinction-related brain regions and enhances contextual extinction learning without affecting renewal

    Directory of Open Access Journals (Sweden)

    Silke eLissek

    2015-02-01

    Full Text Available Renewal in extinction learning describes the recovery of an extinguished response if the extinction context differs from the context present during acquisition and recall. Attention may have a role in contextual modulation of behavior and contribute to the renewal effect, while noradrenaline is involved in attentional processing. In this functional magnetic resonance imaging (fMRI study we investigated the role of the noradrenergic system for behavioral and brain activation correlates of contextual extinction and renewal, with a particular focus upon hippocampus and ventromedial PFC, which have crucial roles in processing of renewal. Healthy human volunteers received a single dose of the NA reuptake inhibitor atomoxetine prior to extinction learning. During extinction of previously acquired cue-outcome associations, cues were presented in a novel context (ABA or in the acquisition context (AAA. In recall, all cues were again presented in the acquisition context. Atomoxetine participants (ATO showed significantly faster extinction compared to placebo (PLAC. However, atomoxetine did not affect renewal. Hippocampal activation was higher in ATO during extinction and recall, as was ventromedial PFC activation, except for ABA recall. Moreover, ATO showed stronger recruitment of insula, anterior cingulate, and dorsolateral/orbitofrontal PFC. Across groups, cingulate, hippocampus and vmPFC activity during ABA extinction correlated with recall performance, suggesting high relevance of these regions for processing the renewal effect. In summary, the noradrenergic system appears to be involved in the modification of established associations during extinction learning and thus has a role in behavioral flexibility. The assignment of an association to a context and the subsequent decision on an adequate response, however, presumably operate largely independently of noradrenergic mechanisms.

  16. Relationship between exploitation, oscillation, MSY and extinction.

    Science.gov (United States)

    Ghosh, Bapan; Kar, T K; Legovic, T

    2014-10-01

    We give answers to two important problems arising in current fisheries: (i) how maximum sustainable yield (MSY) policy is influenced by the initial population level, and (ii) how harvesting, oscillation and MSY are related to each other in prey-predator systems. To examine the impact of initial population on exploitation, we analyze a single species model with strong Allee effect. It is found that even when the MSY exists, the dynamic solution may not converge to the equilibrium stock if the initial population level is higher but near the critical threshold level. In a prey-predator system with Allee effect in the prey species, the initial population does not have such important impact neither on MSY nor on maximum sustainable total yield (MSTY). However, harvesting the top predator may cause extinction of all species if odd number of trophic levels exist in the ecosystem. With regard to the second problem, we study two prey-predator models and establish that increasing harvesting effort either on prey, predator or both prey and predator destroys previously existing oscillation. Moreover, equilibrium stock both at MSY and MSTY level is stable. We also discuss the validity of found results to other prey-predator systems. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Are Isolated Indigenous Populations Headed toward Extinction?

    Directory of Open Access Journals (Sweden)

    Robert S Walker

    Full Text Available At least 50 indigenous groups spread across lowland South America remain isolated and have only intermittent and mostly hostile interactions with the outside world. Except in emergency situations, the current policy of governments in Brazil, Colombia, and Peru towards isolated tribes is a "leave them alone" strategy, in which isolated groups are left uncontacted. However, these no-contact policies are based on the assumption that isolated populations are healthy and capable of persisting in the face of mounting external threats, and that they can maintain population viability in the long-term. Here, we test this assumption by tracking the sizes and movements of cleared horticultural areas made by 8 isolated groups over the last 10-14 years. We used deforestation data derived from remote sensing Landsat satellite sensors to identify clearings, and those were then validated and assessed with high-resolution imagery. We found only a single example of a relatively large and growing population (c. 50 cleared ha and 400 people, whereas all of the other 7 groups exhibited much smaller villages and gardens with no sizable growth through time. These results indicated that the smaller groups are critically endangered, and it prompts an urgent re-thinking of policies toward isolated populations, including plans for well-organized contacts that may help save lives and rescue isolated indigenous populations from imminent extinction.

  18. Are Isolated Indigenous Populations Headed toward Extinction?

    Science.gov (United States)

    Walker, Robert S; Kesler, Dylan C; Hill, Kim R

    2016-01-01

    At least 50 indigenous groups spread across lowland South America remain isolated and have only intermittent and mostly hostile interactions with the outside world. Except in emergency situations, the current policy of governments in Brazil, Colombia, and Peru towards isolated tribes is a "leave them alone" strategy, in which isolated groups are left uncontacted. However, these no-contact policies are based on the assumption that isolated populations are healthy and capable of persisting in the face of mounting external threats, and that they can maintain population viability in the long-term. Here, we test this assumption by tracking the sizes and movements of cleared horticultural areas made by 8 isolated groups over the last 10-14 years. We used deforestation data derived from remote sensing Landsat satellite sensors to identify clearings, and those were then validated and assessed with high-resolution imagery. We found only a single example of a relatively large and growing population (c. 50 cleared ha and 400 people), whereas all of the other 7 groups exhibited much smaller villages and gardens with no sizable growth through time. These results indicated that the smaller groups are critically endangered, and it prompts an urgent re-thinking of policies toward isolated populations, including plans for well-organized contacts that may help save lives and rescue isolated indigenous populations from imminent extinction.

  19. Giant comets and mass extinctions of life

    Science.gov (United States)

    Napier, W. M.

    2015-03-01

    I find evidence for clustering in age of well-dated impact craters over the last 500 Myr. At least nine impact episodes are identified, with durations whose upper limits are set by the dating accuracy of the craters. Their amplitudes and frequency are inconsistent with an origin in asteroid breakups or Oort cloud disturbances, but are consistent with the arrival and disintegration in near-Earth orbits of rare, giant comets, mainly in transit from the Centaur population into the Jupiter family and Encke regions. About 1 in 10 Centaurs in Chiron-like orbits enter Earth-crossing epochs, usually repeatedly, each such epoch being generally of a few thousand years' duration. On time-scales of geological interest, debris from their breakup may increase the mass of the near-Earth interplanetary environment by two or three orders of magnitude, yielding repeated episodes of bombardment and stratospheric dusting. I find a strong correlation between these bombardment episodes and major biostratigraphic and geological boundaries, and propose that episodes of extinction are most effectively driven by prolonged encounters with meteoroid streams during bombardment episodes. Possible mechanisms are discussed.

  20. Mammal extinctions in the Vallesian (Upper Miocene)

    Science.gov (United States)

    Agusti, J.; Moya-Sola, S.

    The term Vallesian was created by Crusafont (1950) to designate the first European Mammalian palaeofaunas containing the equid Hipparion, the remainder of the faunas being composed of typical elements coming from the Middle Miocene such as Micromeryx, Euprox, Sansanosmilus, Pseudaelurus, and Listriodon. Thus, the Aragonian-Vallesian boundary does not show a strong change among European Miocene mammalian faunas (Agusti et al., 1984). On the other hand, the Lower Vallesian/Upper Vallesian transition corresponds to a major biotic crisis. This boudnary is characterized by the disappearence of most of the Aragonian artiodactyl forms such as Protragocerus, Miotragocerus, Listriodon, Hyotherium, Parachleusastochoerus, etc. Among the rodents, this crisis affects the family Eomyidae and most of the cricetid and glirid species. On the other hand, a number of eastern elements appear in the area at the same time. This is the case of the suid Schizochoerus and the murid Progonomys. Other eastern forms are Tragoportax, Graecoryx, Adcrocuta, Paramachairodus, Microstonyx, etc. Most of these are typical elements of the next Mammal stage, the Turolian. Thus, whereas the Lower Vallesian fauna has a typical Aragonian composition except for Hipparion. After the Middle Vallesian event, the Upper Vallesian faunas are already largely Turolian in character. The possible factors involved in this extinction event are discussed.

  1. Semiconductor plasmonic crystals : active control of THz extinction

    NARCIS (Netherlands)

    Schaafsma, M.C.; Gomez Rivas, J.

    2013-01-01

    We investigate theoretically the enhanced THz extinction by periodic arrays of semiconductor particles. Scattering particles of doped semiconductors can sustain localized surface plasmon polaritons, which can be diffractively coupled giving rise to surface lattice resonances. These resonances are

  2. Extinction correction in white X-ray and neutron diffraction

    International Nuclear Information System (INIS)

    Tomiyoshi, S.; Yamada, M.; Watanabe, H.

    1980-01-01

    Extinction effects in white-beam X-ray and neutron diffraction are considered. In white-beam diffraction, a small deviation of the wavelength from the Bragg condition Δlambda is a variable which represents the line profile of the diffraction peaks, so that by using the new parameter Δlambda the theory is converted to one in white-beam diffraction. It is shown that for a convex crystal, primary extinction agrees with the results calculated already for monochromatic diffraction. The same relation is shown to hold in secondary extinction. It is concluded that extinction theory derived for monochromatic diffraction is applicable without any modification in white-beam diffraction. (Auth.)

  3. Observational evidence of dust evolution in galactic extinction curves

    Energy Technology Data Exchange (ETDEWEB)

    Cecchi-Pestellini, Cesare [INAF-Osservatorio Astronomico di Palermo, P.zza Parlamento 1, I-90134 Palermo (Italy); Casu, Silvia; Mulas, Giacomo [INAF-Osservatorio Astronomico di Cagliari, Via della Scienza, I-09047 Selargius (Italy); Zonca, Alberto, E-mail: cecchi-pestellini@astropa.unipa.it, E-mail: silvia@oa-cagliari.inaf.it, E-mail: gmulas@oa-cagliari.inaf.it, E-mail: azonca@oa-cagliari.inaf.it [Dipartimento di Fisica, Università di Cagliari, Strada Prov.le Monserrato-Sestu Km 0.700, I-09042 Monserrato (Italy)

    2014-04-10

    Although structural and optical properties of hydrogenated amorphous carbons are known to respond to varying physical conditions, most conventional extinction models are basically curve fits with modest predictive power. We compare an evolutionary model of the physical properties of carbonaceous grain mantles with their determination by homogeneously fitting observationally derived Galactic extinction curves with the same physically well-defined dust model. We find that a large sample of observed Galactic extinction curves are compatible with the evolutionary scenario underlying such a model, requiring physical conditions fully consistent with standard density, temperature, radiation field intensity, and average age of diffuse interstellar clouds. Hence, through the study of interstellar extinction we may, in principle, understand the evolutionary history of the diffuse interstellar clouds.

  4. Motor Extinction in Distinct Reference Frames: A Double Dissociation

    Directory of Open Access Journals (Sweden)

    Jennifer Heidler-Gary

    2013-01-01

    Full Text Available Objective: Test the hypothesis that right hemisphere stroke can cause extinction of left hand movements or movements of either hand held in left space, when both are used simultaneously, possibly depending on lesion site.

  5. Manipulating parameters of reinforcement to reduce problem behavior without extinction.

    Science.gov (United States)

    Kunnavatana, S Shanun; Bloom, Sarah E; Samaha, Andrew L; Slocum, Timothy A; Clay, Casey J

    2018-04-01

    Differential reinforcement of alternative behavior (DRA) most often includes extinction as a treatment component. However, extinction is not always feasible and it can be counter-therapeutic if implemented without optimal treatment integrity. Researchers have successfully implemented DRA without extinction by manipulating various parameters of reinforcement such that alternative behavior is favored. We extended previous research by assessing three participants' sensitivities to quality, magnitude, and immediacy using arbitrary responses and reinforcers that maintain problem behavior. The results were used to implement an intervention for problem behavior using DRA without extinction. Our findings indicate that arbitrary responses can be used to identify individual and relative sensitivity to parameters of reinforcement for reinforcers that maintain problem behavior. Treatment was effective for all participants when we manipulated parameters of reinforcement to which they were most sensitive, and, for two participants, the treatment was less effective when we manipulated parameters to which they were least sensitive. © 2018 Society for the Experimental Analysis of Behavior.

  6. Safety Behavior After Extinction Triggers a Return of Threat Expectancy

    NARCIS (Netherlands)

    van Uijen, S.L.; Leer, A.; Engelhard, I.M.

    2018-01-01

    Safety behavior is involved in the maintenance of anxiety disorders, presumably because it prevents the violation of negative expectancies. Recent research showed that safety behavior is resistant to fear extinction. This fear conditioning study investigated whether safety behavior after fear

  7. Extinction order and altered community structure rapidly disrupt ecosystem functioning.

    Science.gov (United States)

    Larsen, Trond H; Williams, Neal M; Kremen, Claire

    2005-05-01

    By causing extinctions and altering community structure, anthropogenic disturbances can disrupt processes that maintain ecosystem integrity. However, the relationship between community structure and ecosystem functioning in natural systems is poorly understood. Here we show that habitat loss appeared to disrupt ecosystem functioning by affecting extinction order, species richness and abundance. We studied pollination by bees in a mosaic of agricultural and natural habitats in California and dung burial by dung beetles on recently created islands in Venezuela. We found that large-bodied bee and beetle species tended to be both most extinction-prone and most functionally efficient, contributing to rapid functional loss. Simulations confirmed that extinction order led to greater disruption of function than predicted by random species loss. Total abundance declined with richness and also appeared to contribute to loss of function. We demonstrate conceptually and empirically how the non-random response of communities to disturbance can have unexpectedly large functional consequences.

  8. Extinction of Aversive Classically Conditioned Human Sexual Response

    NARCIS (Netherlands)

    Brom, M.; Laan, E.; Everaerd, W.; Spinhoven, P.; Both, S.

    INTRODUCTION: Research has shown that acquired subjective likes and dislikes are quite resistant to extinction. Moreover, studies on female sexual response demonstrated that diminished genital arousal and positive affect toward erotic stimuli due to aversive classical conditioning did not extinguish

  9. An extinct vertebrate preserved by its living hybridogenetic descendant.

    Science.gov (United States)

    Dubey, Sylvain; Dufresnes, Christophe

    2017-10-06

    Hybridogenesis is a special mode of hybrid reproduction where one parental genome is eliminated and the other is transmitted clonally. We propose that this mechanism can perpetuate the genome of extinct species, based on new genetic data from Pelophylax water frogs. We characterized the genetic makeup of Italian hybridogenetic hybrids (P. kl. hispanicus and esculentus) and identified a new endemic lineage of Eastern-Mediterranean origin as one parental ancestor of P. kl. hispanicus. This taxon is nowadays extinct in the wild but its germline subsists through its hybridogenetic descendant, which can thus be considered as a "semi living fossil". Such rare situation calls for realistic efforts of de-extinction through selective breeding without genetic engineering, and fuels the topical controversy of reviving long extinct species. "Ghost" species hidden by taxa of hybrid origin may be more frequent than suspected in vertebrate groups that experienced a strong history of hybridization and semi-sexual reproduction.

  10. The ultraviolet interstellar extinction curve in the Pleiades

    Science.gov (United States)

    Witt, A. N.; Bohlin, R. C.; Stecher, T. P.

    1981-01-01

    The wavelength dependence of ultraviolet extinction in the Pleiades dust clouds has been determined from IUE observations of HD 23512, the brightest heavily reddened member of the Pleiades cluster. There is evidence for an anomalously weak absorption bump at 2200 A, followed by an extinction rise in the far ultraviolet with an essentially normal slope. A relatively weak absorption band at 2200 A and a weak diffuse absorption band at 4430 A seem to be common characteristics of dust present in dense clouds. Evidence is presented which suggests that the extinction characteristics found for HD 23512 are typical for a class of extinction curves observed in several cases in the Galaxy and in the LMC.

  11. Trends in the extinction of carnivores in Madagascar

    Directory of Open Access Journals (Sweden)

    Cartagena–Matos, B.

    2017-02-01

    Full Text Available The extinction of top predators, such as mammalian carnivores can lead to dramatic changes in foodweb structure and ecosystem dynamics. Since all native Malagasy terrestrial mammalian carnivores are endemic, their extinction implies a significant loss of biodiversity in Madagascar. Here we review the literature on Madagascar’s mammalian carnivores, aiming to determine which species are most likely to become extinct in the near future in view of the factors threatening their survival. We scored each factor according to its impact on the species. According to our results, the giant–striped mongoose, Galidictis grandidieri, is the most likely species to next become extinct. This is no surprise because this species is considered one of the rarest carnivores in the world, inhabiting only a small, threatened forest ecosystem. Our results emphasize the need for robust data about each species to help and support decision–makers implement conservation measures.

  12. Climate warming drives local extinction: Evidence from observation and experimentation

    Science.gov (United States)

    Panetta, Anne Marie; Stanton, Maureen L.; Harte, John

    2018-01-01

    Despite increasing concern about elevated extinction risk as global temperatures rise, it is difficult to confirm causal links between climate change and extinction. By coupling 25 years of in situ climate manipulation with experimental seed introductions and both historical and current plant surveys, we identify causal, mechanistic links between climate change and the local extinction of a widespread mountain plant (Androsace septentrionalis). Climate warming causes precipitous declines in population size by reducing fecundity and survival across multiple life stages. Climate warming also purges belowground seed banks, limiting the potential for the future recovery of at-risk populations under ameliorated conditions. Bolstered by previous reports of plant community shifts in this experiment and in other habitats, our findings not only support the hypothesis that climate change can drive local extinction but also foreshadow potentially widespread species losses in subalpine meadows as climate warming continues. PMID:29507884

  13. Climate warming drives local extinction: Evidence from observation and experimentation.

    Science.gov (United States)

    Panetta, Anne Marie; Stanton, Maureen L; Harte, John

    2018-02-01

    Despite increasing concern about elevated extinction risk as global temperatures rise, it is difficult to confirm causal links between climate change and extinction. By coupling 25 years of in situ climate manipulation with experimental seed introductions and both historical and current plant surveys, we identify causal, mechanistic links between climate change and the local extinction of a widespread mountain plant ( Androsace septentrionalis ). Climate warming causes precipitous declines in population size by reducing fecundity and survival across multiple life stages. Climate warming also purges belowground seed banks, limiting the potential for the future recovery of at-risk populations under ameliorated conditions. Bolstered by previous reports of plant community shifts in this experiment and in other habitats, our findings not only support the hypothesis that climate change can drive local extinction but also foreshadow potentially widespread species losses in subalpine meadows as climate warming continues.

  14. Puerarin Alleviates Neuropathic Pain by Inhibiting Neuroinflammation in Spinal Cord

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2014-01-01

    Full Text Available Neuropathic pain responds poorly to drug treatments, and partial relief is achieved in only about half of the patients. Puerarin, the main constituent of Puerariae Lobatae Radix, has been used extensively in China to treat hypertension and tumor. The current study examined the effects of puerarin on neuropathic pain using two most commonly used animal models: chronic constriction injury (CCI and diabetic neuropathy. We found that consecutive intrathecal administration of puerarin (4–100 nM for 7 days inhibited the mechanical and thermal nociceptive response induced by CCI and diabetes without interfering with the normal pain response. Meanwhile, in both models puerarin inhibited the activation of microglia and astroglia in the spinal dorsal horn. Puerarin also reduced the upregulated levels of nuclear factor-κB (NF-κB and other proinflammatory cytokines, such as IL-6, IL-1β, and TNF-α, in the spinal cord. In summary, puerarin alleviated CCI- and diabetes-induced neuropathic pain, and its effectiveness might be due to the inhibition of neuroinflammation in the spinal cord. The anti-inflammation effect of puerarin might be related to the suppression of spinal NF-κB activation and/or cytokines upregulation. We conclude that puerarin has a significant effect on alleviating neuropathic pain and thus may serve as a therapeutic approach for neuropathic pain.

  15. Resource Assessment for Afghanistan and Alleviation of Terrorism

    Science.gov (United States)

    Shroder, J. F.

    2002-05-01

    Mineral and water resources in Afghanistan may be the best means by which redevelopment of the country can be used to alleviate future terrorism. Remote-sensing analysis of snow, ice, resources, and topography in Afghanistan, and development of digital elevation models with ASTER imagery and previously classified, large scale topographic maps from the Department of Defense enable better assessment and forecasting resources in the country. Adequate resource assessment and planning is viewed as critical to alleviation of one cause of the problems associated with the fertilization of terrorism in Afghanistan. Long-term diminution of meltwater resources in Afghanistan is exemplified by the disastrous and famine-inducing droughts of the present time and three decades prior, as well as by the early Landsat assessment of glacier resources sponsored by USGS and now brought up-to-date with current imagery. Extensive cold-war projects undertaken by both the USSR and USA generated plentiful essential mineral, hydrocarbon, hydrogeological, and hydrological data, including an extensive stream gauging and vital irrigation network now adversly affected or destroyed entirely by decades of war. Analysis, measurement, prediction, rehabilitation, and reconstruction of critical resource projects are regarded as most critical elements in the war on terrorism in this portion of the world. The GLIMS (Global Land Ice Measurements from Space) Project, initially sponsored by USGS, has established our group as the Regional Center for Afghanistan and Pakistan, in which the above concepts serve as guiding research precepts.

  16. Alleviating cancer patients' suffering: whose responsibility is it?

    Science.gov (United States)

    Grau, Jorge

    2009-07-01

    In medicine, we have historically been better at learning about the body and disease than we have at understanding the human beings who come to us with the ailments. We have acted to relieve pain, consoling patients and families as a complement, but done little to understand and alleviate suffering as a fundamental part of our practice. In fact, only in more recent decades has "suffering" been conceptualized as something apart from pain, associated with distress and its causes. It was Eric T. Cassell, in his ground-breaking work in the 1980s, who posed the need to consider alleviation of suffering and treatment of illness as twin-and equally important-obligations of the medical profession. Suffering is defined as a negative, complex emotional and cognitive state, characterized by feeling under constant threat and powerless to confront it, having drained the physical and psycho-social resources that might have made resistance possible. This unique depletion of personal resources is key to understanding suffering.

  17. Puerarin alleviates neuropathic pain by inhibiting neuroinflammation in spinal cord.

    Science.gov (United States)

    Liu, Ming; Liao, Kaijun; Yu, Changxi; Li, Xuejun; Liu, Suhuan; Yang, Shuyu

    2014-01-01

    Neuropathic pain responds poorly to drug treatments, and partial relief is achieved in only about half of the patients. Puerarin, the main constituent of Puerariae Lobatae Radix, has been used extensively in China to treat hypertension and tumor. The current study examined the effects of puerarin on neuropathic pain using two most commonly used animal models: chronic constriction injury (CCI) and diabetic neuropathy. We found that consecutive intrathecal administration of puerarin (4-100 nM) for 7 days inhibited the mechanical and thermal nociceptive response induced by CCI and diabetes without interfering with the normal pain response. Meanwhile, in both models puerarin inhibited the activation of microglia and astroglia in the spinal dorsal horn. Puerarin also reduced the upregulated levels of nuclear factor-κB (NF-κB) and other proinflammatory cytokines, such as IL-6, IL-1β, and TNF-α, in the spinal cord. In summary, puerarin alleviated CCI- and diabetes-induced neuropathic pain, and its effectiveness might be due to the inhibition of neuroinflammation in the spinal cord. The anti-inflammation effect of puerarin might be related to the suppression of spinal NF-κB activation and/or cytokines upregulation. We conclude that puerarin has a significant effect on alleviating neuropathic pain and thus may serve as a therapeutic approach for neuropathic pain.

  18. Seed Dispersal Anachronisms: Rethinking the Fruits Extinct Megafauna Ate

    OpenAIRE

    Guimarães, Paulo R.; Galetti, Mauro; Jordano, Pedro

    2008-01-01

    Background: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals .103 kg), yet these dispersers were extinct in South America 10–15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics. Methodology/Principal Findings: We introduce an operational definition of megafaunal fruits and perform a comparativ...

  19. Extinction threshold of a population in spatial and stochastic model

    OpenAIRE

    Soroka, Yevheniia; Rublyov, Bogdan

    2016-01-01

    In this study, spatial stochastic and logistic model (SSLM) describing dynamics of a population of a certain species was analysed. The behaviour of the extinction threshold as a function of model parameters was studied. More specifically, we studied how the critical values for the model parameters that separate the cases of extinction and persistence depend on the spatial scales of the competition and dispersal kernels. We compared the simulations and analytical results to examine if and how ...

  20. Flightless birds: When did the dodo become extinct?

    Science.gov (United States)

    Roberts, David L.; Solow, Andrew R.

    2003-11-01

    The extinction of the dodo (Raphus cucullatus L.; Fig. 1) is commonly dated to the last confirmed sighting in 1662, reported by Volkert Evertsz on an islet off Mauritius. By this time, the dodo had become extremely rare - the previous sighting having been 24 years earlier - but the species probably persisted unseen beyond this date. Here we use a statistical method to establish the actual extinction time of the dodo as 1690, almost 30 years after its most recent sighting.

  1. Phenomenon of primary and secondary extinction in textured material

    International Nuclear Information System (INIS)

    Kryshtab, T.G.; Palacios G, J.; Mazin, M.O.

    2002-01-01

    A new X-ray diffraction method is proposed for a more exact calculation of pole figures to determine the crystallite orientation distribution function (CODF) in textured materials, by the introduction of a correction of the integrated intensity of the diffracted beam due to the phenomenon of extinction. Besides, for the case of a symmetrical Bragg reflection from an ''infinitely thick'' flat parallel plate textured sample a simple solution is developed for the problem of separation and determination of primary and secondary extinction parameters, which can be present simultaneously. The determination of these parameters gives additional information about crystallite structure and allows us to evaluate the average subgrains size and their disorientation, respectively. In this work according to the dynamic diffraction theory, it is shown that the extinction length, which is directly connected with the phenomenon of primary extinction, in the Bragg geometry for σ polarization (perpendicular) is independent on the wavelength used for a given reflection. On the other hand, the additional contribution from secondary extinction depends on X-ray wavelength due to the change of effective absorption coefficient. Considering this fact, the calculations of pole density and the parameters of primary and secondary extinction are performed using the same strong reflection for two different wavelengths and, for one of these wavelengths, a second order of reflection. For confirmation of the proposed method a partially cold rolled aluminium sample and an aluminium powder standard sample were measured. The corrected pole densities, the values of primary and secondary extinction and the average sizes of perfect coherent areas and average angle of disorientation of subgrains in the selected directions were obtained. The obtained results show that the precise X-ray diffraction characterization of textured materials requires the consideration, in general, of primary as well as secondary

  2. Many-beam electron extinction distances in zirconium

    International Nuclear Information System (INIS)

    Cann, C.D.

    1977-05-01

    Many-beam extinction distances have been calculated for twenty-two of the lowest order reflections in zirconium. Ten beams comprising the directly transmitted and the nine lowest order systematic reflections were included in each calculation. Extinction distances for each reflection were determined for electron accelerating voltages of 100 and 200 kV, both at the exact Bragg condition and at deviations up to two Bragg angles from this condition. (author)

  3. Deficient fear extinction memory in posttraumatic stress disorder.

    Science.gov (United States)

    Wicking, Manon; Steiger, Frauke; Nees, Frauke; Diener, Slawomira J; Grimm, Oliver; Ruttorf, Michaela; Schad, Lothar R; Winkelmann, Tobias; Wirtz, Gustav; Flor, Herta

    2016-12-01

    Posttraumatic stress disorder (PTSD) might be maintained by deficient extinction memory. We used a cued fear conditioning design with extinction and a post-extinction phase to provoke the return of fear and examined the role of the interplay of amygdala, hippocampus and prefrontal regions. We compared 18 PTSD patients with two healthy control groups: 18 trauma-exposed subjects without PTSD (nonPTSD) and 18 healthy controls (HC) without trauma experience. They underwent a three-day ABC-conditioning procedure in a functional magnetic resonance imaging scanner. Two geometric shapes that served as conditioned stimuli (CS) were presented in the context of virtual reality scenes. Electric painful stimuli were delivered after one of the two shapes (CS+) during acquisition (in context A), while the other (CS-) was never paired with pain. Extinction was performed in context B and extinction memory was tested in a novel context C. The PTSD patients showed significantly higher differential skin conductance responses than the non-PTSD and HC and higher differential amygdala and hippocampus activity than the HC in context C. In addition, elevated arousal to the CS+ during extinction and to the CS- throughout the experiment was present in the PTSD patients but self-reported differential valence or contingency were not different. During extinction recall, differential amygdala activity correlated positively with the intensity of numbing and ventromedial prefrontal cortex activity correlated positively with behavioral avoidance. PTSD patients show heightened return of fear in neural and peripheral measures. In addition, self-reported arousal was high to both danger (CS+) and safety (CS-) cues. These results suggest that a deficient maintenance of extinction and a failure to identify safety signals might contribute to PTSD symptoms, whereas non-PTSD subjects seem to show normal responses. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Global Amphibian Extinction Risk Assessment for the Panzootic Chytrid Fungus

    OpenAIRE

    Rödder, Dennis; Kielgast, Jos; Bielby, Jon; Schmidtlein, Sebastian; Bosch, Jaime; Garner, Trenton W. J.; Veith, Michael; Walker, Susan; Fisher, Matthew C.; Lötters, Stefan

    2009-01-01

    Species are being lost at increasing rates due to anthropogenic effects, leading to the recognition that we are witnessing the onset of a sixth mass extinction. Emerging infectious disease has been shown to increase species loss and any attempts to reduce extinction rates need to squarely confront this challenge. Here, we develop a procedure for identifying amphibian species that are most at risk from the effects of chytridiomycosis by combining spatial analyses of key host life-history varia...

  5. Profitless delays for extinction in nonautonomous Lotka-Volterra system

    Science.gov (United States)

    Liu, Shengqiang; Chen, Lansun

    2001-12-01

    We study the delayed periodic n-species Lotka-Voterra systems where the growth rate of each species is not always positive. The sufficient conditions for the extinction that are independent of the delays are obtained. Some known results are improved and generalized. Our results suggest that under some conditions, the introduction and the variance of the time delays can be both harmless and profitless. Discussion about the effect of time delays on the extinction of the system is also advanced.

  6. Ultraviolet extinction properties of grains in the interstellar medium

    International Nuclear Information System (INIS)

    Seab, C.G.

    1982-01-01

    The IUE satellite has been used to derive UV extinction curves for 58 stars, ranging in spectral type from 06 the A5, and with E(B-V) reddenings from 0.09 to 1.59 mag. The average reddening is 0.63 mag. Anomalous extinction curves were particularly sought in the project. The most striking discovery was the near absence of the 2175 Angstrom extinction feature from the line of sight towards HD 29647 in the Taurus dark cloud. The collection of data has been analyzed in several ways. Patterns are sought in the collection as a whole, in homogeneous subsets of the data, and in relation to diffuse band strengths. Apart from some well-known correlations, only a few weak relationships are found, including a quasi-relationship between the 2175 Angstrom bump and the 4430 Angstrom diffuse band that persists after the basic E(B-V) dependencies have been removed. A search for diffuse bands in the UV was done by stacking 48 of the extinction curves to reduce the noise. The stacked curve showed no evidence of new diffuse bands. To help interpret the anomalous extinction curves, a theoretical simulation of grain processing in interstellar shocks was undertaken. Shock processing was found to cause strong 2175 angstorm bumps and high far UV extinction. Comparison to extinction curves associated with supernova remnants confirms the predictions of strong 2175 Angstrom bumps, and partially confirms the prediction of high far UV extinction. The implications of all of these results are considered for the two most prominent grain models

  7. A fundamental role for context in instrumental learning and extinction

    OpenAIRE

    Bouton, Mark E.; Todd, Travis P.

    2014-01-01

    The purpose of this article is to review recent research that has investigated the effects of context change on instrumental (operant) learning. The first part of the article discusses instrumental extinction, in which the strength of a reinforced instrumental behavior declines when reinforcers are withdrawn. The results suggest that extinction of either simple or discriminated operant behavior is relatively specific to the context in which it is learned: As in prior studies of Pavlovian exti...

  8. How humans drive speciation as well as extinction

    DEFF Research Database (Denmark)

    Bull, Joseph William; Maron, M.

    2016-01-01

    influence upon divergence in microorganisms. Even if human activities resulted in no net loss of species diversity by balancing speciation and extinction rates, this would probably be deemed unacceptable. We discuss why, based upon ‘no net loss’ conservation literature— considering phylogenetic diversity...... and other metrics, risk aversion, taboo trade-offs and spatial heterogeneity. We conclude that evaluating speciation alongside extinction could result in more nuanced understanding of biosphere trends, clarifying what it is we actually value about biodiversity....

  9. Alcohol Ataxia Tolerance: Extinction Cues, Spontaneous Recovery, and Relapse

    OpenAIRE

    Brooks, Douglas C.

    2005-01-01

    This article reviews ethanol ataxic tolerance experiments with rats that investigate spontaneous recovery after extinction and how extinction-related cues reduce this recovery. Tolerance to the effects of many drugs including ethanol is partly the result of Pavlovian conditioning. Tolerance to the ataxic (and other) effects of ethanol depends critically upon the circumstances in which the drug is administered. Tolerance shows other characteristics common in Pavlovian conditioning, e.g.,. it c...

  10. The Effect of D-Cycloserine on Immediate vs. Delayed Extinction of Learned Fear

    Science.gov (United States)

    Langton, Julia M.; Richardson, Rick

    2010-01-01

    We compared the effect of D-cycloserine (DCS) on immediate (10 min after conditioning) and delayed (24 h after conditioning) extinction of learned fear in rats. DCS facilitated both immediate and delayed extinction when the drug was administered after extinction training. However, DCS did not facilitate immediate extinction when administered prior…

  11. Medial Prefrontal Cortex Activation Facilitates Re-Extinction of Fear in Rats

    Science.gov (United States)

    Chang, Chun-hui; Maren, Stephen

    2011-01-01

    It has been suggested that reduced infralimbic (IL) cortical activity contributes to impairments of fear extinction. We therefore explored whether pharmacological activation of the IL would facilitate extinction under conditions it normally fails (i.e., immediate extinction). Rats received auditory fear conditioning 1 h before extinction training.…

  12. Bepotastine besilate ophthalmic solution 1.5% for alleviating nasal symptoms in patients with allergic conjunctivitis

    Directory of Open Access Journals (Sweden)

    Cavet ME

    2018-03-01

    Full Text Available Megan E Cavet,1 Paul J Gomes,2 Warner W Carr,3 Jon I Williams4 1Bausch + Lomb, Rochester, NY, 2Ora, Andover, MA, 3Allergy and Asthma Associates of Southern California, Mission Viejo, CA, 4Bausch + Lomb, Irvine, CA, USA Background: Bepotastine besilate ophthalmic solution (BBOS 1.5% is a topical antihistamine for the treatment of ocular itching associated with allergic conjunctivitis (AC. Allergic rhinitis and AC are common comorbid conditions. We explored the efficacy of BBOS 1.5% in alleviating nasal symptoms in an integrated analysis of two Phase III conjunctival allergen challenge (CAC studies and a Phase IV environmental allergen study. Methods: In the Phase III trials, a CAC was performed 15 minutes, 8 hours, and 16 hours following ocular instillation of BBOS 1.5% (n=78 or placebo (n=79, and subjects evaluated nasal symptoms. In the environmental study, subjects instilled BBOS 1.5% (n=123 or placebo (n=122 twice daily and nasal symptoms were evaluated over 2 weeks. Results: In the Phase III trials, BBOS 1.5% had reduced CAC-induced nasal congestion and pruritus at 15 minutes and 8 hours postdosing and rhinorrhea and a non-ocular composite-symptom score (sum of nasal scores plus ear or palate pruritus at all time points postdosing (all P≤0.01 vs placebo. In the Phase IV environmental study, BBOS 1.5% reduced sneezing and nasal pruritus over 2 weeks and median number of days to improvement of nasal pruritus and total nasal symptom score (sum for rhinorrhea, sneezing, nasal pruritus, and nasal congestion; P≤0.04 vs placebo. Additionally, investigator-reported improvement in overall ocular (pruritus, hyperemia, tearing and nasal symptoms was greater with BBOS 1.5% vs placebo (P≤0.03. Conclusion: Results of these exploratory analyses indicate that topical ocular BBOS 1.5% reduced nasal symptoms, supporting its use for alleviating rhinitis symptoms associated with AC. Keywords: bepotastine besilate, nasal symptoms, allergic rhinitis

  13. Dexamethasone facilitates fear extinction and safety discrimination in PTSD: A placebo-controlled, double-blind study.

    Science.gov (United States)

    Michopoulos, Vasiliki; Norrholm, Seth D; Stevens, Jennifer S; Glover, Ebony M; Rothbaum, Barbara O; Gillespie, Charles F; Schwartz, Ann C; Ressler, Kerry J; Jovanovic, Tanja

    2017-09-01

    Psychophysiological hallmarks of posttraumatic stress disorder (PTSD) include exaggerated fear responses, impaired inhibition and extinction of conditioned fear, and decreased discrimination between safety and fear cues. This increased fear load associated with PTSD can be a barrier to effective therapy thus indicating the need for new treatments to reduce fear expression in people with PTSD. One potential biological target for reducing fear expression in PTSD is the hypothalamic-pituitary-adrenal (HPA) axis, which is dysregulated in PTSD. Recent translational rodent studies and cross-sectional clinical studies have shown that dexamethasone administration and the resulting suppression of cortisol in individuals with PTSD leads to a decrease in the fear responses characteristic of PTSD. These data, taken together, suggest that dexamethasone may serve as a novel pharmacologic intervention for heightened fear responses in PTSD. We conducted a double-blind, placebo-controlled trial to test our hypothesis that dexamethasone administration and the concomitant suppression of HPA axis hyperactivity would attenuate fear expression and enhance fear extinction in individuals with PTSD. Study participants (n=62) were recruited from Grady Memorial Hospital in Atlanta, GA. Participants were randomized to receive dexamethasone or placebo prior to fear conditioning and extinction, in a counterbalanced design (treatments separated by a week). Both PTSD- (n=37) and PTSD+ (n=25) participants showed significant startle increases in the presence of the danger signal during placebo and dexamethasone treatments (all pextinction blocks during both conditions (p's≤0.001), with PTSD+ participants showing deficits in fear extinction and safety discrimination in the placebo condition. Notably, extinction and discrimination deficits in PTSD+ subjects were markedly reversed with dexamethasone (pextinction and discrimination in individuals with PTSD. Copyright © 2017 Elsevier Ltd. All rights

  14. Impaired fear extinction in adolescent rodents: Behavioural and neural analyses.

    Science.gov (United States)

    Baker, Kathryn D; Bisby, Madelyne A; Richardson, Rick

    2016-11-01

    Despite adolescence being a developmental window of vulnerability, up until very recently there were surprisingly few studies on fear extinction during this period. Here we summarise the recent work in this area, focusing on the unique behavioural and neural characteristics of fear extinction in adolescent rodents, and humans where relevant. A prominent hypothesis posits that anxiety disorders peak during late childhood/adolescence due to the non-linear maturation of the fear inhibition neural circuitry. We discuss evidence that impaired extinction retention in adolescence is due to subregions of the medial prefrontal cortex and amygdala mediating fear inhibition being underactive while other subregions that mediate fear expression are overactive. We also review work on various interventions and surprising circumstances which enhance fear extinction in adolescence. This latter work revealed that the neural correlates of extinction in adolescence are different to that in younger and older animals even when extinction retention is not impaired. This growing body of work highlights that adolescence is a unique period of development for fear inhibition. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Resurrection of DNA function in vivo from an extinct genome.

    Directory of Open Access Journals (Sweden)

    Andrew J Pask

    2008-05-01

    Full Text Available There is a burgeoning repository of information available from ancient DNA that can be used to understand how genomes have evolved and to determine the genetic features that defined a particular species. To assess the functional consequences of changes to a genome, a variety of methods are needed to examine extinct DNA function. We isolated a transcriptional enhancer element from the genome of an extinct marsupial, the Tasmanian tiger (Thylacinus cynocephalus or thylacine, obtained from 100 year-old ethanol-fixed tissues from museum collections. We then examined the function of the enhancer in vivo. Using a transgenic approach, it was possible to resurrect DNA function in transgenic mice. The results demonstrate that the thylacine Col2A1 enhancer directed chondrocyte-specific expression in this extinct mammalian species in the same way as its orthologue does in mice. While other studies have examined extinct coding DNA function in vitro, this is the first example of the restoration of extinct non-coding DNA and examination of its function in vivo. Our method using transgenesis can be used to explore the function of regulatory and protein-coding sequences obtained from any extinct species in an in vivo model system, providing important insights into gene evolution and diversity.

  16. Can CCM law properly represent all extinction curves?

    International Nuclear Information System (INIS)

    Geminale, Anna; Popowski, Piotr

    2005-01-01

    We present the analysis of a large sample of lines of sight with extinction curves covering wavelength range from near-infrared (NIR) to ultraviolet (UV). We derive total to selective extinction ratios based on the Cardelli, Clayton and Mathis (1989, CCM) law, which is typically used to fit the extinction data both for diffuse and dense interstellar medium. We conclude that the CCM law is able to fit most of the extinction curves in our sample. We divide the remaining lines of sight with peculiar extinction into two groups according to two main behaviors: a) the optical/IR or/and UV wavelength region cannot be reproduced by the CCM formula; b) the optical/NIR and UV extinction data are best fit by the CCM law with different values of R v . We present examples of such curves. The study of both types of peculiar cases can help us to learn about the physical processes that affect dust in the interstellar medium, e.g., formation of mantles on the surface of grains, evaporation, growing or shattering

  17. Attention as the 'glue' for object integration in parietal extinction.

    Science.gov (United States)

    Conci, Markus; Groß, Julia; Keller, Ingo; Müller, Hermann J; Finke, Kathrin

    2018-04-01

    Patients with unilateral, parietal brain damage frequently show visual extinction, which manifests in a failure to identify contralesional stimuli when presented simultaneously with other, ipsilesional stimuli (but full awareness for single stimulus presentations). Extinction reflects an impairment of spatial selective attention, leaving basic preattentive processing unaffected. For instance, access to bilaterally grouped objects is usually spared in extinction, suggesting that grouping occurs at a stage preceding (in the patients: abnormally biased) spatial-attentional selection. Here, we reinvestigated this notion by comparing (largely between participants, but also within a single-case participant) conditions with objects that varied in their dominant direction of grouping: from the attended to the non-attended hemifield (data from Conci et al., 2009) versus from the non-attended to the attended hemifield (new data). We observe complete absence of extinction when shape completion extended from the attended hemifield. By contrast, extinction was not diminished when object groupings propagate from the unattended hemifield. Moreover, we found the individual severity of the attentional impairment (assessed by a standard "inattention" test) to be directly related to the degree of completion in the unattended hemifield. This pattern indicates that grouping can overcome visual extinction only when object integration departs from the attended visual field, implying, contrary to many previous accounts, that attention is crucial for grouping to be initiated. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Fish extinctions alter nutrient recycling in tropical freshwaters.

    Science.gov (United States)

    McIntyre, Peter B; Jones, Laura E; Flecker, Alexander S; Vanni, Michael J

    2007-03-13

    There is increasing evidence that species extinctions jeopardize the functioning of ecosystems. Overfishing and other human influences are reducing the diversity and abundance of fish worldwide, but the ecosystem-level consequences of these changes have not been assessed quantitatively. Recycling of nutrients is one important ecosystem process that is directly influenced by fish. Fish species vary widely in the rates at which they excrete nitrogen and phosphorus; thus, altering fish communities could affect nutrient recycling. Here, we use extensive field data on nutrient recycling rates and population sizes of fish species in a Neotropical river and Lake Tanganyika, Africa, to evaluate the effects of simulated extinctions on nutrient recycling. In both of these species-rich ecosystems, recycling was dominated by relatively few species, but contributions of individual species differed between nitrogen and phosphorus. Alternative extinction scenarios produced widely divergent patterns. Loss of the species targeted by fishermen led to faster declines in nutrient recycling than extinctions in order of rarity, body size, or trophic position. However, when surviving species were allowed to increase after extinctions, these compensatory responses had strong moderating effects even after losing many species. Our results underscore the complexity of predicting the consequences of extinctions from species-rich animal communities. Nevertheless, the importance of exploited species in nutrient recycling suggests that overfishing could have particularly detrimental effects on ecosystem functioning.

  19. Resistance to extinction, generalization decrement, and conditioned reinforcement.

    Science.gov (United States)

    Dulaney, Alana E; Bell, Matthew C

    2008-06-01

    This study investigated generalization decrement during an extinction resistance-to-change test for pigeon key pecking using a two-component multiple schedule with equal variable-interval 3-min schedules and different reinforcer amounts (one component presented 2-s access to reinforcement and the other 8s). After establishing baseline responding, subjects were assigned to one of the two extinction conditions: hopper stimuli (hopper and hopper light were activated but no food was available) or Control (inactive hopper and hopper light). Responding in the 8-s component was more resistant to extinction than responding in the 2-s component, the hopper stimuli group was more resistant to extinction compared to the Control group, and an interaction between amount of reinforcement, extinction condition, and session block was present. This finding supports generalization decrement as a factor that influences resistance to extinction. Hopper-time data (the amount of time subjects spent with their heads in the hopper) were compared to resistance-to-change data in an investigation of the role of conditioned reinforcement on resistance to change.

  20. Linking indices for biodiversity monitoring to extinction risk theory.

    Science.gov (United States)

    McCarthy, Michael A; Moore, Alana L; Krauss, Jochen; Morgan, John W; Clements, Christopher F

    2014-12-01

    Biodiversity indices often combine data from different species when used in monitoring programs. Heuristic properties can suggest preferred indices, but we lack objective ways to discriminate between indices with similar heuristics. Biodiversity indices can be evaluated by determining how well they reflect management objectives that a monitoring program aims to support. For example, the Convention on Biological Diversity requires reporting about extinction rates, so simple indices that reflect extinction risk would be valuable. We developed 3 biodiversity indices that are based on simple models of population viability that relate extinction risk to abundance. We based the first index on the geometric mean abundance of species and the second on a more general power mean. In a third index, we integrated the geometric mean abundance and trend. These indices require the same data as previous indices, but they also relate directly to extinction risk. Field data for butterflies and woodland plants and experimental studies of protozoan communities show that the indices correlate with local extinction rates. Applying the index based on the geometric mean to global data on changes in avian abundance suggested that the average extinction probability of birds has increased approximately 1% from 1970 to 2009. © 2014 The Authors. Conservation Biology published by Wiley Periodicals, Inc., on behalf of the Society for Conservation Biology.