Science.gov

Sample records for intense longitudinal retreatment

  1. Retreat, Hell!

    ERIC Educational Resources Information Center

    Sims, Wil

    1978-01-01

    Describes an annual fall retreat for junior college newspaper staffs, which involves a program of workshops and discussions about problems, goals, and staff members' roles; offers advice on planning such a retreat. (GW)

  2. Exploring Intensive Longitudinal Measures of Student Engagement in Blended Learning

    ERIC Educational Resources Information Center

    Henrie, Curtis R.; Bodily, Robert; Manwaring, Kristine C.; Graham, Charles R.

    2015-01-01

    In this exploratory study we used an intensive longitudinal approach to measure student engagement in a blended educational technology course, collecting both self-report and observational data. The self-report measure included a simple survey of Likert-scale and open-ended questions given repeatedly during the semester. Observational data were…

  3. Leveraging Intensive Longitudinal Data to Better Understand Health Behaviors*

    PubMed Central

    Timms, Kevin P.; Martín, César A.; Rivera, Daniel E.; Hekler, Eric B.; Riley, William

    2015-01-01

    Behavioral scientists have historically relied on static modeling methodologies. The rise in mobile and wearable sensors has made intensive longitudinal data (ILD)—behavioral data measured frequently over time—increasingly available. Consequently, analytical frameworks are emerging that seek to reliably quantify dynamics reflected in these data. Employing an input-output perspective, dynamical systems models from engineering can characterize time-varying behaviors as processes of change. Specifically, ILD and parameter estimation routines from system identification can be leveraged together to offer parsimonious and quantitative descriptions of dynamic behavioral constructs. The utility of this approach for facilitating a better understanding of health behaviors is illustrated with two examples. In the first example, dynamical systems models are developed for Social Cognitive Theory (SCT), a prominent concept in behavioral science that considers interrelationships between personal factors, the environment, and behaviors. Estimated models are then obtained that explore the role of SCT in a physical activity intervention. The second example uses ILD to model day-to-day changes in smoking levels as a craving-mediated process of behavior change. PMID:25571579

  4. A Time-Varying Effect Model for Intensive Longitudinal Data

    PubMed Central

    Tan, Xianming; Shiyko, Mariya P.; Li, Runze; Li, Yuelin; Dierker, Lisa

    2011-01-01

    Understanding temporal change in human behavior and psychological processes is a central issue in the behavioral sciences. With technological advances, intensive longitudinal data (ILD) are increasingly generated by studies of human behavior that repeatedly administer assessments over time. ILD offer unique opportunities to describe temporal behavioral changes in detail and identify related environmental and psychosocial antecedents and consequences. Traditional analytical approaches impose strong parametric assumptions about the nature of change in the relationship between time-varying covariates and outcomes of interest. This paper introduces time-varying effect models (TVEM) that explicitly model changes in the association between ILD covariates and ILD outcomes over time in a flexible manner. In this article, we describes unique research questions that the TVEM addresses, outline the model-estimation procedure, share a SAS macro for implementing the model, demonstrate model utility with a simulated example, and illustrate model applications in ILD collected as part of a smoking-cessation study to explore the relationship between smoking urges and self-efficacy during the course of the pre- and post- cessation period. PMID:22103434

  5. Analytical Solutions for the Nonlinear Longitudinal Drift Compression (Expansion) of Intense Charged Particle Beams

    SciTech Connect

    Edward A. Startsev; Ronald C. Davidson

    2004-04-09

    To achieve high focal spot intensities in heavy ion fusion, the ion beam must be compressed longitudinally by factors of ten to one hundred before it is focused onto the target. The longitudinal compression is achieved by imposing an initial velocity profile tilt on the drifting beam. In this paper, the problem of longitudinal drift compression of intense charged particle beams is solved analytically for the two important cases corresponding to a cold beam, and a pressure-dominated beam, using a one-dimensional warm-fluid model describing the longitudinal beam dynamics.

  6. Mean-field thalamocortical modeling of longitudinal EEG acquired during intensive meditation training.

    PubMed

    Saggar, Manish; Zanesco, Anthony P; King, Brandon G; Bridwell, David A; MacLean, Katherine A; Aichele, Stephen R; Jacobs, Tonya L; Wallace, B Alan; Saron, Clifford D; Miikkulainen, Risto

    2015-07-01

    Meditation training has been shown to enhance attention and improve emotion regulation. However, the brain processes associated with such training are poorly understood and a computational modeling framework is lacking. Modeling approaches that can realistically simulate neurophysiological data while conforming to basic anatomical and physiological constraints can provide a unique opportunity to generate concrete and testable hypotheses about the mechanisms supporting complex cognitive tasks such as meditation. Here we applied the mean-field computational modeling approach using the scalp-recorded electroencephalogram (EEG) collected at three assessment points from meditating participants during two separate 3-month-long shamatha meditation retreats. We modeled cortical, corticothalamic, and intrathalamic interactions to generate a simulation of EEG signals recorded across the scalp. We also present two novel extensions to the mean-field approach that allow for: (a) non-parametric analysis of changes in model parameter values across all channels and assessments; and (b) examination of variation in modeled thalamic reticular nucleus (TRN) connectivity over the retreat period. After successfully fitting whole-brain EEG data across three assessment points within each retreat, two model parameters were found to replicably change across both meditation retreats. First, after training, we observed an increased temporal delay between modeled cortical and thalamic cells. This increase provides a putative neural mechanism for a previously observed reduction in individual alpha frequency in these same participants. Second, we found decreased inhibitory connection strength between the TRN and secondary relay nuclei (SRN) of the modeled thalamus after training. This reduction in inhibitory strength was found to be associated with increased dynamical stability of the model. Altogether, this paper presents the first computational approach, taking core aspects of physiology and

  7. Poisson Growth Mixture Modeling of Intensive Longitudinal Data: An Application to Smoking Cessation Behavior

    ERIC Educational Resources Information Center

    Shiyko, Mariya P.; Li, Yuelin; Rindskopf, David

    2012-01-01

    Intensive longitudinal data (ILD) have become increasingly common in the social and behavioral sciences; count variables, such as the number of daily smoked cigarettes, are frequently used outcomes in many ILD studies. We demonstrate a generalized extension of growth mixture modeling (GMM) to Poisson-distributed ILD for identifying qualitatively…

  8. Long path-length experimental studies of longitudinal phenomena in intense beams

    NASA Astrophysics Data System (ADS)

    Beaudoin, B. L.; Haber, I.; Kishek, R. A.; Bernal, S.; Koeth, T. W.

    2016-05-01

    Intense charged particle beams are nonneutral plasmas as they can support a host of plasma waves and instabilities. The longitudinal physics, for a long beam, can often be reasonably described by a 1-D cold-fluid model with a geometry factor to account for the transverse effects. The plasma physics of such beams has been extensively studied theoretically and computationally for decades, but until recently, the only experimental measurements were carried out on relatively short linacs. This work reviews experimental studies over the past five years on the University of Maryland Electron Ring, investigating longitudinal phenomena over time scales of thousands of plasma periods, illustrating good agreement with simulations.

  9. Participation in an Intensive Longitudinal Study with Weekly Web Surveys Over 2.5 Years

    PubMed Central

    Barber, Jennifer; Kusunoki, Yasamin; Schulz, Paul

    2016-01-01

    Background Technological advances have made it easier for researchers to collect more frequent longitudinal data from survey respondents via personal computers, smartphones, and other mobile devices. Although technology has led to an increase in data-intensive longitudinal studies, little is known about attrition from such studies or the differences between respondents who complete frequently administered surveys in a timely manner, and respondents who do not. Objective We examined respondent characteristics and behaviors associated with continued and on-time participation in a population-based intensive longitudinal study, using weekly web-based survey interviews over an extended period. Methods We analyzed data from the Relationship Dynamics and Social Life study, an intensive longitudinal study that collected weekly web-based survey interviews for 2.5 years from 1003 18- and 19-year-olds to investigate factors shaping the dynamics of their sexual behavior, contraceptive use, and pregnancies. Results Ordinary least squares and logistic regression analyses showed background respondent characteristics measured at baseline were associated with the number of days respondents remained enrolled in the study, the number of interviews they completed, and the odds that they were late completing interviews. In addition, we found that changes in pregnancy-related behaviors reported in the weekly interviews were associated with late completion of interviews. Specifically, after controlling for sociodemographic, personality, contact information, and prior experience variables, we found that weekly reports such as starting to have sex (odds ratio [OR] 1.17, 95% CI 1.03-1.32, P=.01), getting a new partner (OR 1.76, 95% CI 1.53-2.03, P<.001), stopping the use of contraception (OR 1.28, 95% CI 1.10-1.49, P=.001), and having a new pregnancy (OR 5.57, 95% CI 4.26-7.29, P<.001) were significantly associated with late survey completion. However, young women who reported changes in

  10. Relating multi-sequence longitudinal intensity profiles and clinical covariates in incident multiple sclerosis lesions.

    PubMed

    Sweeney, Elizabeth M; Shinohara, Russell T; Dewey, Blake E; Schindler, Matthew K; Muschelli, John; Reich, Daniel S; Crainiceanu, Ciprian M; Eloyan, Ani

    2016-01-01

    The formation of multiple sclerosis (MS) lesions is a complex process involving inflammation, tissue damage, and tissue repair - all of which are visible on structural magnetic resonance imaging (MRI) and potentially modifiable by pharmacological therapy. In this paper, we introduce two statistical models for relating voxel-level, longitudinal, multi-sequence structural MRI intensities within MS lesions to clinical information and therapeutic interventions: (1) a principal component analysis (PCA) and regression model and (2) function-on-scalar regression models. To do so, we first characterize the post-lesion incidence repair process on longitudinal, multi-sequence structural MRI from 34 MS patients as voxel-level intensity profiles. For the PCA regression model, we perform PCA on the intensity profiles to develop a voxel-level biomarker for identifying slow and persistent, long-term intensity changes within lesion tissue voxels. The proposed biomarker's ability to identify such effects is validated by two experienced clinicians (a neuroradiologist and a neurologist). On a scale of 1 to 4, with 4 being the highest quality, the neuroradiologist gave the score on the first PC a median quality rating of 4 (95% CI: [4,4]), and the neurologist gave the score a median rating of 3 (95% CI: [3,3]). We then relate the biomarker to the clinical information in a mixed model framework. Treatment with disease-modifying therapies (p < 0.01), steroids (p < 0.01), and being closer to the boundary of abnormal signal intensity (p < 0.01) are all associated with return of a voxel to an intensity value closer to that of normal-appearing tissue. The function-on-scalar regression model allows for assessment of the post-incidence time points at which the covariates are associated with the profiles. In the function-on-scalar regression, both age and distance to the boundary were found to have a statistically significant association with the lesion intensities at some time point

  11. Relating multi-sequence longitudinal intensity profiles and clinical covariates in incident multiple sclerosis lesions

    PubMed Central

    Sweeney, Elizabeth M.; Shinohara, Russell T.; Dewey, Blake E.; Schindler, Matthew K.; Muschelli, John; Reich, Daniel S.; Crainiceanu, Ciprian M.; Eloyan, Ani

    2015-01-01

    The formation of multiple sclerosis (MS) lesions is a complex process involving inflammation, tissue damage, and tissue repair — all of which are visible on structural magnetic resonance imaging (MRI) and potentially modifiable by pharmacological therapy. In this paper, we introduce two statistical models for relating voxel-level, longitudinal, multi-sequence structural MRI intensities within MS lesions to clinical information and therapeutic interventions: (1) a principal component analysis (PCA) and regression model and (2) function-on-scalar regression models. To do so, we first characterize the post-lesion incidence repair process on longitudinal, multi-sequence structural MRI from 34 MS patients as voxel-level intensity profiles. For the PCA regression model, we perform PCA on the intensity profiles to develop a voxel-level biomarker for identifying slow and persistent, long-term intensity changes within lesion tissue voxels. The proposed biomarker's ability to identify such effects is validated by two experienced clinicians (a neuroradiologist and a neurologist). On a scale of 1 to 4, with 4 being the highest quality, the neuroradiologist gave the score on the first PC a median quality rating of 4 (95% CI: [4,4]), and the neurologist gave the score a median rating of 3 (95% CI: [3,3]). We then relate the biomarker to the clinical information in a mixed model framework. Treatment with disease-modifying therapies (p < 0.01), steroids (p < 0.01), and being closer to the boundary of abnormal signal intensity (p < 0.01) are all associated with return of a voxel to an intensity value closer to that of normal-appearing tissue. The function-on-scalar regression model allows for assessment of the post-incidence time points at which the covariates are associated with the profiles. In the function-on-scalar regression, both age and distance to the boundary were found to have a statistically significant association with the lesion intensities at some time point

  12. Poisson Growth Mixture Modeling of Intensive Longitudinal Data: An Application to Smoking Cessation Behavior

    PubMed Central

    Shiyko, Mariya P.; Li, Yuelin; Rindskopf, David

    2011-01-01

    Intensive longitudinal data (ILD) have become increasingly common in the social and behavioral sciences; count variables, such as the number of daily smoked cigarettes, are frequently-used outcomes in many ILD studies. We demonstrate a generalized extension of growth mixture modeling (GMM) to Poisson-distributed ILD for identifying qualitatively distinct trajectories in the context of developmental heterogeneity in count data. Accounting for the Poisson outcome distribution is essential for correct model identification and estimation. In addition, setting up the model in a way that is conducive to ILD measures helps with data complexities – large data volume, missing observations, and differences in sampling frequency across individuals. We present technical details of model fitting, summarize an empirical example of patterns of smoking behavior change, and describe research questions the generalized GMM helps to address. PMID:22408365

  13. The importance of physical activity and sleep for affect on stressful days: Two intensive longitudinal studies.

    PubMed

    Flueckiger, Lavinia; Lieb, Roselind; Meyer, Andrea H; Witthauer, Cornelia; Mata, Jutta

    2016-06-01

    We investigated the potential stress-buffering effect of 3 health behaviors-physical activity, sleep quality, and snacking-on affect in the context of everyday life in young adults. In 2 intensive longitudinal studies with up to 65 assessment days over an entire academic year, students (Study 1, N = 292; Study 2, N = 304) reported stress intensity, sleep quality, physical activity, snacking, and positive and negative affect. Data were analyzed using multilevel regression analyses. Stress and positive affect were negatively associated; stress and negative affect were positively associated. The more physically active than usual a person was on a given day, the weaker the association between stress and positive affect (Study 1) and negative affect (Studies 1 and 2). The better than usual a person's sleep quality had been during the previous night, the weaker the association between stress and positive affect (Studies 1 and 2) and negative affect (Study 2). The association between daily stress and positive or negative affect did not differ as a function of daily snacking (Studies 1 and 2). On stressful days, increasing physical activity or ensuring high sleep quality may buffer adverse effects of stress on affect in young adults. These findings suggest potential targets for health-promotion and stress-prevention programs, which could help reduce the negative impact of stress in young adults. (PsycINFO Database Record

  14. What's in a Day? A Guide to Decomposing the Variance in Intensive Longitudinal Data.

    PubMed

    de Haan-Rietdijk, Silvia; Kuppens, Peter; Hamaker, Ellen L

    2016-01-01

    In recent years there has been a growing interest in the use of intensive longitudinal research designs to study within-person processes. Examples are studies that use experience sampling data and autoregressive modeling to investigate emotion dynamics and between-person differences therein. Such designs often involve multiple measurements per day and multiple days per person, and it is not clear how this nesting of the data should be accounted for: That is, should such data be considered as two-level data (which is common practice at this point), with occasions nested in persons, or as three-level data with beeps nested in days which are nested in persons. We show that a significance test of the day-level variance in an empty three-level model is not reliable when there is autocorrelation. Furthermore, we show that misspecifying the number of levels can lead to spurious or misleading findings, such as inflated variance or autoregression estimates. Throughout the paper we present instructions and R code for the implementation of the proposed models, which includes a novel three-level AR(1) model that estimates moment-to-moment inertia and day-to-day inertia. Based on our simulations we recommend model selection using autoregressive multilevel models in combination with the AIC. We illustrate this method using empirical emotion data from two independent samples, and discuss the implications and the relevance of the existence of a day level for the field. PMID:27378986

  15. Phase mixing of relativistically intense longitudinal wave packets in a cold plasma

    NASA Astrophysics Data System (ADS)

    Mukherjee, Arghya; Sengupta, Sudip

    2016-09-01

    Phase mixing of relativistically intense longitudinal wave packets in a cold homogeneous unmagnetized plasma has been studied analytically and numerically using the Dawson Sheet Model. A general expression for phase mixing time ( ω p t m i x ) as a function of amplitude of the wave packet (δ) and width of the spectrum ( Δ k / k ) has been derived. It is found that the phase mixing time crucially depends on the relative magnitude of amplitude "δ" and the spectral width " Δ k / k ". For Δ k / k ≤ 2 ωp 2 δ 2 / c 2 k 2 , ω p t m i x scales with δ as ˜ 1 / δ 5 , whereas for Δ k / k > 2 ωp 2 δ 2 / c 2 k 2 , ω p t m i x scales with δ as ˜ 1 / δ 3 , where ωp is the non-relativistic plasma frequency and c is the speed of light in vacuum. We have also verified the above theoretical scalings using numerical simulations based on the Dawson Sheet Model.

  16. What's in a Day? A Guide to Decomposing the Variance in Intensive Longitudinal Data

    PubMed Central

    de Haan-Rietdijk, Silvia; Kuppens, Peter; Hamaker, Ellen L.

    2016-01-01

    In recent years there has been a growing interest in the use of intensive longitudinal research designs to study within-person processes. Examples are studies that use experience sampling data and autoregressive modeling to investigate emotion dynamics and between-person differences therein. Such designs often involve multiple measurements per day and multiple days per person, and it is not clear how this nesting of the data should be accounted for: That is, should such data be considered as two-level data (which is common practice at this point), with occasions nested in persons, or as three-level data with beeps nested in days which are nested in persons. We show that a significance test of the day-level variance in an empty three-level model is not reliable when there is autocorrelation. Furthermore, we show that misspecifying the number of levels can lead to spurious or misleading findings, such as inflated variance or autoregression estimates. Throughout the paper we present instructions and R code for the implementation of the proposed models, which includes a novel three-level AR(1) model that estimates moment-to-moment inertia and day-to-day inertia. Based on our simulations we recommend model selection using autoregressive multilevel models in combination with the AIC. We illustrate this method using empirical emotion data from two independent samples, and discuss the implications and the relevance of the existence of a day level for the field. PMID:27378986

  17. Neuroendocrine function following traumatic brain injury and subsequent intensive care treatment: a prospective longitudinal evaluation.

    PubMed

    Kleindienst, Andrea; Brabant, Georg; Bock, Christoph; Maser-Gluth, Christiane; Buchfelder, Michael

    2009-09-01

    Neuroendocrine dysfunction following traumatic brain injury (TBI) has been described extensively. However, few studies are longitudinal and most lack subtle radiological, clinical, and repetitive endocrine assessment in the acute phase. Accordingly, we prospectively assessed neuroendocrine function in 71 patients after TBI. Injury was documented by a computed tomography (CT). During the first week, critical clinical data (Glasgow Coma Score, APACHE score), treatment variables such as duration of analgosedation for mechanical ventilation, were related to basal pituitary function. More than 2 years later, a subgroup of patients was re-evaluated using dynamic testing with ACTH and GHRH-arginine tests. The Pearson's correlation analysis and Mann-Whitney rank sum test for group differences were used for statistical analysis. None of the CT findings predicted neuroendocrine dysfunction following TBI. The adaptive response to critical illness with significantly elevated cortisol levels on admission and decreased levels thereafter in patients ventilated for more than 24 h (p < 0.05) was attenuated following severe TBI (p < 0.05). However, the coincidence of low serum cortisol and increased urinary excretion of glucocorticoid metabolites in about 80% of patients challenges the relevance of basal hormone measurements. In ventilated patients, total T3 and free T4 were decreased (p < 0.05), TSH was low on day 3 (p < 0.05), and a gonadotropic insufficiency was present (p < 0.05). The thyrotropic and gonadotropic system recovered completely within the follow-up period. With regard to the somatotropic system, neither brain injury severity nor mechanical ventilation was associated with an insufficiency during the acute phase post-injury. However, initially low GH levels predicted a persistent deficiency (r = 0.731, p < 0.001). We conclude that both severe TBI and prolonged mechanical ventilation result in hormonal disturbances early after injury, suggesting a pathophysiological

  18. Enhanced response inhibition during intensive meditation training predicts improvements in self-reported adaptive socioemotional functioning.

    PubMed

    Sahdra, Baljinder K; MacLean, Katherine A; Ferrer, Emilio; Shaver, Phillip R; Rosenberg, Erika L; Jacobs, Tonya L; Zanesco, Anthony P; King, Brandon G; Aichele, Stephen R; Bridwell, David A; Mangun, George R; Lavy, Shiri; Wallace, B Alan; Saron, Clifford D

    2011-04-01

    We examined the impact of training-induced improvements in self-regulation, operationalized in terms of response inhibition, on longitudinal changes in self-reported adaptive socioemotional functioning. Data were collected from participants undergoing 3 months of intensive meditation training in an isolated retreat setting (Retreat 1) and a wait-list control group that later underwent identical training (Retreat 2). A 32-min response inhibition task (RIT) was designed to assess sustained self-regulatory control. Adaptive functioning (AF) was operationalized as a single latent factor underlying self-report measures of anxious and avoidant attachment, mindfulness, ego resilience, empathy, the five major personality traits (extroversion, agreeableness, conscientiousness, neuroticism, and openness to experience), difficulties in emotion regulation, depression, anxiety, and psychological well-being. Participants in Retreat 1 improved in RIT performance and AF over time whereas the controls did not. The control participants later also improved on both dimensions during their own retreat (Retreat 2). These improved levels of RIT performance and AF were sustained in follow-up assessments conducted approximately 5 months after the training. Longitudinal dynamic models with combined data from both retreats showed that improvement in RIT performance during training influenced the change in AF over time, which is consistent with a key claim in the Buddhist literature that enhanced capacity for self-regulation is an important precursor of changes in emotional well-being. PMID:21500899

  19. LONGITUDINAL AND RADIAL DEPENDENCE OF SOLAR ENERGETIC PARTICLE PEAK INTENSITIES: STEREO, ACE, SOHO, GOES, AND MESSENGER OBSERVATIONS

    SciTech Connect

    Lario, D.; Ho, G. C.; Decker, R. B.; Roelof, E. C.; Aran, A.; Gomez-Herrero, R.; Dresing, N.; Heber, B.

    2013-04-10

    Simultaneous measurements of solar energetic particle (SEP) events by two or more of the spacecraft located near 1 AU during the rising phase of solar cycle 24 (i.e., STEREO-A, STEREO-B, and near-Earth spacecraft such as ACE, SOHO, and GOES) are used to determine the longitudinal dependence of 71-112 keV electron, 0.7-3 MeV electron, 15-40 MeV proton, and 25-53 MeV proton peak intensities measured in the prompt component of SEP events. Distributions of the peak intensities for the selected 35 events with identifiable solar origin are approximated by the form exp [ - ({phi} - {phi}{sub 0}){sup 2}/2{sigma}{sup 2}], where {phi} is the longitudinal separation between the parent active region and the footpoint of the nominal interplanetary magnetic field (IMF) line connecting each spacecraft with the Sun, {phi}{sub 0} is the distribution centroid, and {sigma} determines the longitudinal gradient. The MESSENGER spacecraft, at helioradii R < 1 AU, allows us to determine a lower limit to the radial dependence of the 71-112 keV electron peak intensities measured along IMF lines. We find five events for which the nominal magnetic footpoint of MESSENGER was less than 20 Degree-Sign apart from the nominal footpoint of a spacecraft near 1 AU. Although the expected theoretical radial dependence for the peak intensity of the events observed along the same field line can be approximated by a functional form R {sup -{alpha}} with {alpha} < 3, we find two events for which {alpha} > 3. These two cases correspond to SEP events occurring in a complex interplanetary medium that favored the enhancement of peak intensities near Mercury but hindered the SEP transport to 1 AU.

  20. Intensity of Participation in Organized Youth Activities during the High School Years: Longitudinal Associations with Adjustment

    ERIC Educational Resources Information Center

    Denault, Anne-Sophie; Poulin, Francois; Pedersen, Sara

    2009-01-01

    The goal of this study was to explore the longitudinal associations between youth activity participation and adjustment over the high school years by examining (a) correlations between participation and adjustment growth curves, and (b) bidirectional links between participation and adjustment from one year to the next. Participation was…

  1. Why Intensive Interventions Matter: Longitudinal Studies of Adolescents with Reading Disabilities and Poor Reading Comprehension

    ERIC Educational Resources Information Center

    Solis, Michael; Miciak, Jeremy; Vaughn, Sharon; Fletcher, Jack M.

    2014-01-01

    We describe findings from a series of longitudinal studies utilizing a response to intervention framework implemented over 3 years with students in Grades 6 through 8 with reading disabilities and poor reading comprehension. Students were identified based on reading comprehension scores in Grade 5 (n = 1,083) and then randomized to treatment or…

  2. Control of longitudinal electric field intensity and of the electron temperature in a weakly ionized decaying plasma

    SciTech Connect

    Ivanov, V.A.; Skoblo, Y.E.

    1981-07-01

    The possibility is considered of controlling the intensity of a longitudinal electric field and the electron temperature in a decaying gas-discharge plasma. It is proposed to feed the discharge from a simple circuit that makes possible the control of the electric field in wide dynamic and frequency ranges. The procedure for controlling the field intensity and the electron temperature is experimentally investigated in the afterglow of a discharge in neon at pressures 2--30 torr and currents 10--100 mA. The possibility of arbitrarily varying the electron temperature can be used to investigate the temperature dependences of the constants of the elementary processes that take place in a decaying plasma.

  3. USEPA PATHOGEN EQUIVALENCY COMMITTEE RETREAT

    EPA Science Inventory

    The Pathogen Equivalency Committee held its retreat from September 20-21, 2005 at Hueston Woods State Park in College Corner, Ohio. This presentation will update the PEC’s membership on emerging pathogens, analytical methods, disinfection techniques, risk analysis, preparat...

  4. Influence of supplemental vitamin D on intensity of benign paroxysmal positional vertigo: A longitudinal clinical study

    PubMed Central

    Sheikhzadeh, Mahboobeh; Lotfi, Yones; Mousavi, Abdollah; Heidari, Behzad; Monadi, Mohsen; Bakhshi, Enayatollah

    2016-01-01

    Background: Benign paroxysmal positional vertigo (BPPV) is linked to vitamin D deficiency. This clinical trial aimed to determine the influence of vitamin D supplementation on intensity of BPPV. Methods: The study population was selected consecutively and the diagnosis of BPPV was made by history and clinical examination and exclusion of other conditions. Intensity of BPVV was assessed based on VAS score (0-10). Serum 25-hydroxyvitamin D (25-OHD) was measured using ELISA method and levels < 20 ng/ml was considered a deficiency. All patients received rehabilitation treatment using Epley's maneuver one time per week for one month. Serum 25-OHD deficient patients were classified as treated and non-treated groups (rehabilitation with or without 50.000 IU cholecalciferol weekly for two months).The results of treatment were compared with vitamin D sufficient group as control. All patients were followed-up for 6 months. Results: After two months of treatment, in both vitamin D treated and non-treated groups the intensity of BPPV decreased significantly as compared with control (P=0.001 for both groups) but at endpoint, the intensity of BPPV aggravated and regressed to the baseline value in vitamin D deficient non-treated group (P=0.001) whereas, in vitamin D treated group, improvement of BPPV remained stable and unchanged over the study period. Conclusion: This study indicates that correction of vitamin D deficiency in BPPV provides additional benefit to rehabilitation therapy (Epley maneuver) regarding duration of improvement. These findings suggest serum 25-OHD measurement in recurrent BPPV. PMID:27386060

  5. Smooth transverse and longitudinal focusing in high-intensity ion linacs

    SciTech Connect

    Billen, J.H.; Takeda, Harunori; Young, L.M.

    1996-09-01

    We examine ion linac designs that start with a high energy radio- frequency quadrupole (RFQ) followed by either a drift-tube linac (DTL) or a coupled-cavity drift-tube linac (CCDTL). For high energies a conventional CCL follows the CCDTL. High RFQ output energy allows tailoring the transverse and longitudinal focusing strengths to match into the following structure. When the RFQ beam enters a higher frequency structure, the DTL or CCDTL starts with a low accelerating gradient and large negative synchronous phase. The gradient and phase both ramp up gradually to higher values. Other changes later in the machine are also gradual. Beam dynamics simulations show that these linacs require no separate matching sections. Applications include a cw 100 mA H{sup +} beam from a 350-MHz, 6.7 MeV RFQ injecting a 700 MHz CCDTL and CCL; a 7% duty 28 mA H{sup -} beam from a 402.5 MHz RFQ and DTL injecting 805 MHz structures; a cw 135 mA D{sup +} beam produced by a 175 MHz, 8 MeV RFQ and DTL; and a 2.4% duty, 80 mA H{sup +} beam using a 433 MHz 10 MeV RFQ and a 1300 MHz CCDTL. The machines take advantage of the considerable flexibility of the CCDTL. Designs can use a variety of different transverse focusing lattices. Use of two coupling cavity orientations permits a constant period even when the number of drift tubes per cavity changes along the linac.

  6. A Distributed Network for Intensive Longitudinal Monitoring in Metastatic Triple-Negative Breast Cancer.

    PubMed

    Blau, C Anthony; Ramirez, Arturo B; Blau, Sibel; Pritchard, Colin C; Dorschner, Michael O; Schmechel, Stephen C; Martins, Timothy J; Mahen, Elisabeth M; Burton, Kimberly A; Komashko, Vitalina M; Radenbaugh, Amie J; Dougherty, Katy; Thomas, Anju; Miller, Christopher P; Annis, James; Fromm, Jonathan R; Song, Chaozhong; Chang, Elizabeth; Howard, Kellie; Austin, Sharon; Schmidt, Rodney A; Linenberger, Michael L; Becker, Pamela S; Senecal, Francis M; Mecham, Brigham H; Lee, Su-In; Madan, Anup; Ronen, Roy; Dutkowski, Janusz; Heimfeld, Shelly; Wood, Brent L; Stilwell, Jackie L; Kaldjian, Eric P; Haussler, David; Zhu, Jingchun

    2016-01-01

    Accelerating cancer research is expected to require new types of clinical trials. This report describes the Intensive Trial of OMics in Cancer (ITOMIC) and a participant with triple-negative breast cancer metastatic to bone, who had markedly elevated circulating tumor cells (CTCs) that were monitored 48 times over 9 months. A total of 32 researchers from 14 institutions were engaged in the patient's evaluation; 20 researchers had no prior involvement in patient care and 18 were recruited specifically for this patient. Whole-exome sequencing of 3 bone marrow samples demonstrated a novel ROS1 variant that was estimated to be present in most or all tumor cells. After an initial response to cisplatin, a hypothesis of crizotinib sensitivity was disproven. Leukapheresis followed by partial CTC enrichment allowed for the development of a differential high-throughput drug screen and demonstrated sensitivity to investigational BH3-mimetic inhibitors of BCL-2 that could not be tested in the patient because requests to the pharmaceutical sponsors were denied. The number and size of CTC clusters correlated with clinical status and eventually death. Focusing the expertise of a distributed network of investigators on an intensively monitored patient with cancer can generate high-resolution views of the natural history of cancer and suggest new opportunities for therapy. Optimization requires access to investigational drugs. PMID:26733551

  7. A Distributed Network for Intensive Longitudinal Monitoring in Metastatic Triple-Negative Breast Cancer.

    PubMed

    Blau, C Anthony; Ramirez, Arturo B; Blau, Sibel; Pritchard, Colin C; Dorschner, Michael O; Schmechel, Stephen C; Martins, Timothy J; Mahen, Elisabeth M; Burton, Kimberly A; Komashko, Vitalina M; Radenbaugh, Amie J; Dougherty, Katy; Thomas, Anju; Miller, Christopher P; Annis, James; Fromm, Jonathan R; Song, Chaozhong; Chang, Elizabeth; Howard, Kellie; Austin, Sharon; Schmidt, Rodney A; Linenberger, Michael L; Becker, Pamela S; Senecal, Francis M; Mecham, Brigham H; Lee, Su-In; Madan, Anup; Ronen, Roy; Dutkowski, Janusz; Heimfeld, Shelly; Wood, Brent L; Stilwell, Jackie L; Kaldjian, Eric P; Haussler, David; Zhu, Jingchun

    2016-01-01

    Accelerating cancer research is expected to require new types of clinical trials. This report describes the Intensive Trial of OMics in Cancer (ITOMIC) and a participant with triple-negative breast cancer metastatic to bone, who had markedly elevated circulating tumor cells (CTCs) that were monitored 48 times over 9 months. A total of 32 researchers from 14 institutions were engaged in the patient's evaluation; 20 researchers had no prior involvement in patient care and 18 were recruited specifically for this patient. Whole-exome sequencing of 3 bone marrow samples demonstrated a novel ROS1 variant that was estimated to be present in most or all tumor cells. After an initial response to cisplatin, a hypothesis of crizotinib sensitivity was disproven. Leukapheresis followed by partial CTC enrichment allowed for the development of a differential high-throughput drug screen and demonstrated sensitivity to investigational BH3-mimetic inhibitors of BCL-2 that could not be tested in the patient because requests to the pharmaceutical sponsors were denied. The number and size of CTC clusters correlated with clinical status and eventually death. Focusing the expertise of a distributed network of investigators on an intensively monitored patient with cancer can generate high-resolution views of the natural history of cancer and suggest new opportunities for therapy. Optimization requires access to investigational drugs.

  8. A Distributed Network for Intensive Longitudinal Monitoring in Metastatic Triple-Negative Breast Cancer

    PubMed Central

    Blau, C. Anthony; Ramirez, Arturo B.; Blau, Sibel; Pritchard, Colin C.; Dorschner, Michael O.; Schmechel, Stephen C.; Martins, Timothy J.; Mahen, Elisabeth M.; Burton, Kimberly A.; Komashko, Vitalina M.; Radenbaugh, Amie J.; Dougherty, Katy; Thomas, Anju; Miller, Christopher P.; Annis, James; Fromm, Jonathan R.; Song, Chaozhong; Chang, Elizabeth; Howard, Kellie; Austin, Sharon; Schmidt, Rodney A.; Linenberger, Michael L.; Becker, Pamela S.; Senecal, Francis M.; Mecham, Brigham H.; Lee, Su-In; Madan, Anup; Ronen, Roy; Dutkowski, Janusz; Heimfeld, Shelly; Wood, Brent L.; Stilwell, Jackie L.; Kaldjian, Eric P.; Haussler, David; Zhu, Jingchun

    2016-01-01

    Accelerating cancer research is expected to require new types of clinical trials. This report describes the Intensive Trial of OMics in Cancer (ITOMIC) and a participant with triple-negative breast cancer metastatic to bone, who had markedly elevated circulating tumor cells (CTCs) that were monitored 48 times over 9 months. A total of 32 researchers from 14 institutions were engaged in the patient’s evaluation; 20 researchers had no prior involvement in patient care and 18 were recruited specifically for this patient. Whole-exome sequencing of 3 bone marrow samples demonstrated a novel ROS1 variant that was estimated to be present in most or all tumor cells. After an initial response to cisplatin, a hypothesis of crizotinib sensitivity was disproven. Leukapheresis followed by partial CTC enrichment allowed for the development of a differential high-throughput drug screen and demonstrated sensitivity to investigational BH3-mimetic inhibitors of BCL-2 that could not be tested in the patient because requests to the pharmaceutical sponsors were denied. The number and size of CTC clusters correlated with clinical status and eventually death. Focusing the expertise of a distributed network of investigators on an intensively monitored patient with cancer can generate high-resolution views of the natural history of cancer and suggest new opportunities for therapy. Optimization requires access to investigational drugs. PMID:26733551

  9. Tunable High-Intensity Electron Bunch Train Production Based on Nonlinear Longitudinal Space Charge Oscillation

    NASA Astrophysics Data System (ADS)

    Zhang, Zhen; Yan, Lixin; Du, Yingchao; Zhou, Zheng; Su, Xiaolu; Zheng, Lianmin; Wang, Dong; Tian, Qili; Wang, Wei; Shi, Jiaru; Chen, Huaibi; Huang, Wenhui; Gai, Wei; Tang, Chuanxiang

    2016-05-01

    High-intensity trains of electron bunches with tunable picosecond spacing are produced and measured experimentally with the goal of generating terahertz (THz) radiation. By imposing an initial density modulation on a relativistic electron beam and controlling the charge density over the beam propagation, density spikes of several-hundred-ampere peak current in the temporal profile, which are several times higher than the initial amplitudes, have been observed for the first time. We also demonstrate that the periodic spacing of the bunch train can be varied continuously either by tuning launching phase of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane. Narrow-band coherent THz radiation from the bunch train was also measured with μ J -level energies and tunable central frequency of the spectrum in the range of ˜0.5 to 1.6 THz. Our results pave the way towards generating mJ-level narrow-band coherent THz radiation and driving high-gradient wakefield-based acceleration.

  10. A Longitudinal Study of the TEACCH Program in Different Settings: The Potential Benefits of Low Intensity Intervention in Preschool Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    D'Elia, Lidia; Valeri, Giovanni; Sonnino, Fabiana; Fontana, Ilaria; Mammone, Alessia; Vicari, Stefano

    2014-01-01

    We conducted a longitudinal study of 30 preschool children with autism spectrum disorders (ASDs) to evaluate the potential benefits of the Treatment and Education of Autistic and related Communication Handicapped Children (TEACCH). Fifteen children following a low intensity TEACCH program were assessed four times for autism severity, adaptive…

  11. Columbia Glacier in 1986; 800 meters retreat

    USGS Publications Warehouse

    Krimmel, R.M.

    1987-01-01

    Columbia Glacier, in Prince William Sound, Alaska, continued its rapid retreat in 1986, with a retreat of 800 m. Average velocity of the lower portion of the glacier, 10 September 1986 to 26 January 1987, was three km/yr, or about one-half of the velocity during similar periods for the previous three years. This reduced velocity is a new development in the progression of the retreat, and if the calving rate follows the pattern of previous years, will result in continued retreat. (Author 's abstract)

  12. Longitudinal assessment of quality of life after surgery, conformal brachytherapy, and intensity-modulated radiation therapy for prostate cancer

    PubMed Central

    Zelefsky, Michael J.; Poon, Bing Ying; Eastham, James; Vickers, Andrew; Pei, Xin; Scardino, Peter T.

    2016-01-01

    Purpose We evaluated quality-of-life changes (QoL) in 907 patients treated with either radical prostatectomy (open or laparoscopic), real-time planned conformal brachytherapy, or high-dose intensity-modulated radiotherapy (IMRT) on a prospective IRB-approved longitudinal study. Methods Validated questionnaires given pretreatment (baseline) and at 3, 6, 9, 12, 15, 18, 24, 36, and 48 months addressed urinary function, urinary bother, bowel function, bowel bother, sexual function, and sexual bother. Results At 48 months, surgery had significantly higher urinary incontinence than others (both P<.001), but fewer urinary irritation/obstruction symptoms (all P<.001). Very low levels of bowel dysfunction were observed and only small subsets in each group showed rectal bleeding. Brachytherapy and IMRT showed better sexual function than surgery accounting for baseline function and other factors (delta 14.29 of 100, 95% CI, 8.57–20.01; and delta 10.5, 95% CI, 3.78–17.88). Sexual bother was similar. Four-year outcomes showed persistent urinary incontinence for surgery with more obstructive urinary symptoms for radiotherapy. Using modern radiotherapy delivery, bowel function deterioration is less-often observed. Sexual function was strongly affected in all groups yet significantly less for radiotherapy. Conclusions Treatment selection should include patient preferences and balance predicted disease-free survival over a projected time vs potential impairment of QoL important for the patient. PMID:26780999

  13. Nonsurgical re-treatment of endodontic failures.

    PubMed

    Weine, F S

    1995-03-01

    Endodontic treatment has a very high percentage of success. When failures did occur, many were re-treated with surgery, although nonsurgical re-treatment often was an option. Recently, improvements in instruments for use in endodontic surgery have increased the ability to perform such re-treatments. Even so, this author believes that nonsurgical re-treatment is preferable to surgical intervention whenever possible because of the greater comfort to the patient and the increased indication of failure for amalgam reverse fillings. Advice for recall appointments and evaluations and the correct procedures for re-treating common failures without surgery are presented. These include failures caused by short or incomplete canal fillings, overextended canal fillings, untreated major canals, and chronically draining teeth.

  14. In vitro evaluation of efficacy of different rotary instrument systems for gutta percha removal during root canal retreatment

    PubMed Central

    Joseph, Mercy; Malhotra, Amit; Rao, Murali; Sharma, Abhimanyu; Talwar, Sangeeta

    2016-01-01

    Background Complete removal of old filling material during root canal retreatment is fundamental for predictable cleaning and shaping of canal anatomy. Most of the retreatment methods tested in earlier studies have shown inability to achieve complete removal of root canal filling. Therefore the aim of this investigation was to assess the efficacy of three different rotary nickel titanium retreatment systems and Hedstrom files in removing filling material from root canals. Material and Methods Sixty extracted mandibular premolars were decoronated to leave 15 mm root. Specimen were hand instrumented and obturated using gutta percha and AH plus root canal sealer. After storage period of two weeks, roots were retreated with three (Protaper retreatment files, Mtwo retreatment files, NRT GPR) rotary retreatment instrument systems and Hedstroem files. Subsequently, samples were sectioned longitudinally and examined under stereomicroscope. Digital images were recorded and evaluated using Digital Image Analysing Software. The retreatment time was recorded for each tooth using a stopwatch. The area of canal and the residual filling material was recorded in mm2 and the percentage of remaining filling material on canal walls was calculated. Data was analysed using ANOVA test. Results Significantly less amount of residual filling material was present in protaper and Mtwo instrumented teeth (p < 0.05) compared to NRT GPR and Hedstrom files group. Protaper instruments also required lesser time during removal of filling material followed by Mtwo instruments, NRT GPR files and Hedstrom files. Conclusions None of the instruments were able to remove the filling material completely from root canal. Protaper universal retreatment system and Mtwo retreatment files were more efficient and faster compared to NRT GPR fles and Hedstrom files. Key words:Gutta-percha removal, nickel titanium, root canal retreatment, rotary instruments. PMID:27703601

  15. Ocean forcing drives glacier retreat sometimes

    NASA Astrophysics Data System (ADS)

    Bassis, J. N.; Ultee, E.; Ma, Y.

    2015-12-01

    Observations show that marine-terminating glaciers respond to climate forcing nonlinearly, with periods of slow or negligible glacier advance punctuated by abrupt, rapid retreat. Once glacier retreat has initiated, glaciers can quickly stabilize with a new terminus position. Alternatively, retreat can be sustained for decades (or longer), as is the case for Columbia Glacier, Alaska where retreat initiated ~1984 and continues to this day. Surprisingly, patterns of glacier retreat show ambiguous or even contradictory correlations with atmospheric temperature and glacier surface mass balance. Despite these puzzles, observations increasingly show that intrusion of warm subsurface ocean water into fjords can lead to glacier erosion rates that can account for a substantial portion of the total mass lost from glaciers. Here we use a simplified flowline model to show that even relatively modest submarine melt rates (~100 m/a) near the terminus of grounded glaciers can trigger large increases in iceberg calving leading to rapid glacier retreat. However, the strength of the coupling between submarine melt and calving is a strong function of the geometry of the glacier (bed topography, ice thickness and glacier width). This can lead to irreversible retreat when the terminus is thick and grounded deeply beneath sea level or result in little change when the glacier is relatively thin, grounded in shallow water or pinned in a narrow fjord. Because of the strong dependence on glacier geometry, small perturbations in submarine melting can trigger glaciers in their most advanced—and geometrically precarious—state to undergo sudden retreat followed by much slower re-advance. Although many details remain speculative, our model hints that some glaciers are more sensitive than others to ocean forcing and that some of the nonlinearities of glacier response to climate change may be attributable to variations in difficult-to-detect subsurface water temperatures that need to be better

  16. Do Higher Sea-cliff Retreat Rates Imply Faster Sea-cliff Retreat?

    NASA Astrophysics Data System (ADS)

    Mushkin, A.; Katz, O.; Porat, N.

    2015-12-01

    Inland retreat of sea cliffs in response to post LGM (last glacial maximum) sea-level rise is an ongoing process that affects coastal environments and communities worldwide. Here, we examine a globally recurring pattern where reported sea-cliff retreat rates since the 20th century often appear to exceed longer-term millennial-scale ('background') rates that rarely exceed ~0.1 m/yr. Focusing on Israel's 30-km-long Mediterranean 'Sharon' sea-cliff as a case study we demonstrate that such apparent increase in rates may also reflect a widely acknowledged sampling bias in geologic rate estimates inferred from observation time windows ('Tobs') shorter than process episodicity. We show that this possible bias leads to an ambiguity in conventional rate estimates obtained by averaging observed retreat distances over Tobs, and that as a result despite ubiquitous and robust observations of cliff retreat since the 20th century (e.g., aerial photographs) recent/current retreat rates for many of the world's episodically retreating sea cliffs remain essentially unknown. To address this present limitation in our ability to detect and quantify recent changes in sea-cliff retreat rates we use airborne LiDAR to measure the continuous wave-driven volumetric erosion of collapsed material from the cliff base as an effective upper-bound constraint for the m/yr rate of episodic retreat of the cliff itself. We find that while conventional retreat rate estimates since the 20th century along the Sharon sea cliff artefactually increase up to several m/yr as an inverse function of Tobs, the LiDAR-constrained retreat rates are not susceptible to this sampling bias, are comparable to the cliff's background retreat rate of 0.03-0.07 m/yr since the mid Holocene and thus indicate no recent acceleration in retreat. This ability to unambiguously constrain sea-cliff retreat rates with annual to decadal-scale observations directly impacts the global-scale push to quantify, better understand and

  17. Summary of the RHIC Retreat 2007

    SciTech Connect

    Pilat,F.; Gardner, C.; Montag, C.; Roser, T.

    2008-08-01

    The RHIC Retreat 2007 took place on July 16-17 2007 at the Foxwoods Resort in CT, about 3 weeks after the end of the RHIC Run-7. The goal of the Retreat is traditionally to plan the upcoming run in the light of the results from the previous one, by providing a snapshot of the present understanding of the machine and a forum for free and frank discussion. A particular attention was paid to the challenge of increasing the time at store, and the related issue of system reliability. An interesting Session covered all new developments aimed to improve the machine performance and luminosity. In Section 2 we summarize the results from Run-7 for RHIC and the injectors and discuss the present objectives of the RHIC program and performance. Sections 3-6 are summaries of the Retreat sessions focused on preparation for deuteron gold and polarized protons, respectively, machine availability and new developments.

  18. Twelfth-Grade Student Work Intensity Linked to Later Educational Attainment and Substance Use: New Longitudinal Evidence

    ERIC Educational Resources Information Center

    Bachman, Jerald G.; Staff, Jeremy; O'Malley, Patrick M.; Schulenberg, John E.; Freedman-Doan, Peter

    2011-01-01

    Long hours of paid employment during high school have been linked to a variety of problem behaviors, but questions remain about whether and to what extent work intensity makes any causal contribution. This study addresses those questions by focusing on how 12th-grade work intensity is associated with substance use and educational attainment in the…

  19. On the retreat of forested, cohesive riverbanks

    NASA Astrophysics Data System (ADS)

    Pizzuto, Jim; O'Neal, Michael; Stotts, Stephanie

    2010-04-01

    Data from the Brandywine Creek in Pennsylvania and the South River in Virginia document spatial and temporal patterns describing the retreat of gently curving bends with forested riparian zones containing a mix of very large and smaller trees, cohesive banks, and slow rates of migration (˜ 0.1 m/yr). Field data include 2.5 years of bank profile surveys, measurements of tree morphology, and ground-based laser scanner (LiDAR) surveys repeated biannually. These banks retreat through a cycle of erosion on decadal timescales. Initially, small volumes (mean = 0.173 m 3 per bank erosion event) of soil are removed between large trees growing on the bank. Near trees, the rate of bank retreat is initially negligible, creating a scalloped bank morphology buttressed by large trees. As the trees are increasingly exposed to the flow, they become slowly undercut, gradually leaning into the channel and sliding down to the toe of the bank, eventually toppling into the river after a few years, which restarts the cycle. A magnitude-frequency analysis of monitoring data from the Brandywine Creek indicates that the effective bank erosion event only 0.11 m 3; thus, forested bank retreat is dominated by small soil failures. Large erosion events, many associated with trees toppling into the river, greatly increase the variance of time-averaged rates of bank erosion, such that almost 4 years of monitoring are needed to measure time-averaged rates of erosion to within an accuracy of 10%. Because of the limited spatial extent of our survey data and the absence of large discharges, these results are provisional. Improved process-based models to predict the retreat of forested riverbanks should account for the spatial structure of riparian forests and the interactions between the flow, the gradual removal of bank soils, and the ongoing efforts of the trees to remain attached to the bank.

  20. The allegheny general modification of the Harvard Breast Cosmesis Scale for the retreated breast.

    PubMed

    Trombetta, Mark; Julian, Thomas B; Kim, Yongbok; Werts, E Day; Parda, David

    2009-10-01

    The use of brachytherapy--and to a lesser extent, external-beam radiotherapy--in the management of locally recurrent breast cancer following ipsilateral breast tumor recurrence (IBTR) followed by repeat breast-conservation surgery and irradiation is currently an area of intense study. The current cosmetic scoring system is inadequate to score the outcome resulting from retreatment because it does not account for the cosmetic effect of the initial treatment. We propose a modification of the scale for patients who undergo retreatment--the Allegheny General Modification of the Harvard/NSABP/RTOG scoring scale.

  1. A Longitudinal Investigation of the Effects of Computer Anxiety on Performance in a Computing-Intensive Environment

    ERIC Educational Resources Information Center

    Buche, Mari W.; Davis, Larry R.; Vician, Chelley

    2007-01-01

    Computers are pervasive in business and education, and it would be easy to assume that all individuals embrace technology. However, evidence shows that roughly 30 to 40 percent of individuals experience some level of computer anxiety. Many academic programs involve computing-intensive courses, but the actual effects of this exposure on computer…

  2. The Board Retreat: For Listening, Learning and Understanding.

    ERIC Educational Resources Information Center

    Read, James W.

    Retreats, which have been used by churches and corporations for some time, are currently being looked into by college presidents and boards of trustees as a means of training and problem solving. While many types of retreats may not be appropriate for boards, a well-planned working retreat can be an effective way for trustees to: (1) really get to…

  3. Microorganism penetration in dentinal tubules of instrumented and retreated root canal walls. In vitro SEM study

    PubMed Central

    Al-Sulaiman, Alaa; Al-Rasheed, Fellwa; Alnajjar, Fatimah; Al-Abdulwahab, Bander; Al-Badah, Abdulhakeem

    2014-01-01

    Objectives This in vitro study aimed to investigate the ability of Candida albicans (C. albicans) and Enterococcus faecalis (E. faecalis) to penetrate dentinal tubules of instrumented and retreated root canal surface of split human teeth. Materials and Methods Sixty intact extracted human single-rooted teeth were divided into 4 groups, negative control, positive control without canal instrumentation, instrumented, and retreated. Root canals in the instrumented group were enlarged with endodontic instruments, while root canals in the retreated group were enlarged, filled, and then removed the canal filling materials. The teeth were split longitudinally after canal preparation in 3 groups except the negative control group. The teeth were inoculated with both microorganisms separately and in combination. Teeth specimens were examined by scanning electron microscopy (SEM), and the depth of penetration into the dentinal tubules was assessed using the SMILE view software (JEOL Ltd). Results Penetration of C. albicans and E. faecalis into the dentinal tubules was observed in all 3 groups, although penetration was partially restricted by dentin debris of tubules in the instrumented group and remnants of canal filling materials in the retreated group. In all 3 groups, E. faecalis penetrated deeper into the dentinal tubules by way of cell division than C. albicans which built colonies and penetrated by means of hyphae. Conclusions Microorganisms can easily penetrate dentinal tubules of root canals with different appearance based on the microorganism size and status of dentinal tubules. PMID:25383343

  4. Moraine formation during an advance/retreat cycle at a temperate alpine glacier

    NASA Astrophysics Data System (ADS)

    Brook, M.; Quincey, D.; Winkler, S.

    2012-04-01

    Mountain glaciers are highly sensitive to variations in temperature and precipitation, and so moraine records from such systems are strong indicators of climate change. Due to the prevailing trend of retreat of the majority of mountain glaciers globally over the last few decades, there are limited opportunities to observe moraine formation, especially at temperate alpine glaciers. In the Southern Alps of New Zealand, while glaciers have all experienced a major retreat since the late 19th century, within this loss of ice mass, there has been a distinct variance in individual glacier response. Indeed, while Tasman Glacier, the longest glacier in the Southern Alps has thinned and entered into the current phase of calving retreat in the early 1990s, the steeper, more responsive glaciers to the west of the Main Divide, such as Franz Josef and Fox Glacier have experienced more elaborate advance/retreat phases. We focus on moraine formation at Fox Glacier, a c. 12.5 km long valley glacier terminating at 300 m above sea level. Fox Glacier retreated substantially since the 1930s, before advancing 800 m between the mid-1980s and 1999. A minor retreat then followed until 2005, succeeded by a 300 m re-advance until 2007-8. Continued retreat and down-wasting has since followed. Superimposed on this alternating advance/retreat cycle, have been minor winter re-advances. Sedimentological and morphological information were combined with detailed observations, historical photos and recent time-lapse photography of the terminus. Characteristics of several modes of moraine formation have been observed: (1) the late 20th century advance culminated in a broad <5 m high terminal moraine, formed by an admixture of "bulldozed" proglacial sediments and dumping of supraglacial material; (2) the 21st century short-lived advances were characterized by 1-2 m high (often multi-crested) ridges with a "saw-tooth" plan-form controlled by longitudinal crevasses outcropping at the terminus; (3) time

  5. Retreatments after multifocal intraocular lens implantation: an analysis

    PubMed Central

    Gundersen, Kjell Gunnar; Makari, Sarah; Ostenstad, Steffen; Potvin, Rick

    2016-01-01

    Purpose To determine the incidence and etiology of required retreatment after multifocal intraocular lens (IOL) implantation and to evaluate the methods and clinical outcomes of retreatment. Patients and methods A retrospective chart review of 416 eyes of 209 patients from one site that underwent uncomplicated cataract surgery with multifocal IOL implantation. Biometry, the IOL, and refractive data were recorded after the original implantation, with the same data recorded after retreatment. Comments related to vision were obtained both before and after retreatment for retreated patients. Results The multifocal retreatment rate was 10.8% (45/416 eyes). The eyes that required retreatment had significantly higher residual refractive astigmatism compared with those who did not require retreatment (1.21±0.51 D vs 0.51±0.39 D, P<0.01). The retreatment rate for the two most commonly implanted primary IOLs, blended bifocal (10.5%, 16/152) and bilateral trifocal (6.9%, 14/202) IOLs, was not statistically significantly different (P=0.12). In those requiring retreatment, refractive-related complaints were most common. Retreatment with refractive corneal surgery, in 11% of the eyes, and piggyback IOLs, in 89% of the eyes, was similarly successful, improving patient complaints 78% of the time. Conclusion Complaints related to ametropia were the main reasons for retreatment. Residual astigmatism appears to be an important determinant of retreatment rate after multifocal IOL implantation. Retreatment can improve symptoms for a high percentage of patients; a piggyback IOL is a viable retreatment option. PMID:27041983

  6. The Course of Pain Intensity in Patients Undergoing Herniated Disc Surgery: A 5-Year Longitudinal Observational Study

    PubMed Central

    Dorow, Marie; Löbner, Margrit; Stein, Janine; Pabst, Alexander; Konnopka, Alexander; Meisel, Hans J.; Günther, Lutz; Meixensberger, Jürgen; Stengler, Katarina; König, Hans-Helmut; Riedel-Heller, Steffi G.

    2016-01-01

    Objectives The aims of this study are to answer the following questions (1) How does the pain intensity of lumbar and cervical disc surgery patients change within a postoperative time frame of 5 years? (2) Which sociodemographic, medical, work-related, and psychological factors are associated with postoperative pain in lumbar and cervical disc surgery patients? Methods The baseline survey (T0; n = 534) was conducted 3.6 days (SD 2.48) post-surgery in the form of face-to-face interviews. The follow-up interviews were conducted 3 months (T1; n = 486 patients), 9 months (T2; n = 457), 15 months (T3; n = 438), and 5 years (T4; n = 404) post-surgery. Pain intensity was measured on a numeric rating-scale (NRS 0–100). Estimated changes to and influences on postoperative pain by random effects were accounted by regression models. Results Average pain decreased continuously over time in patients with lumbar herniated disc (Wald Chi² = 25.97, p<0.001). In patients with cervical herniated disc a reduction of pain was observed, albeit not significant (Chi² = 7.02, p = 0.135). Two predictors were associated with postoperative pain in lumbar and cervical disc surgery patients: the subjective prognosis of gainful employment (p<0.001) and depression (p<0.001). Conclusion In the majority of disc surgery patients, a long-term reduction of pain was observed. Cervical surgery patients seemed to benefit less from surgery than the lumbar surgery patients. A negative subjective prognosis of gainful employment and stronger depressive symptoms were associated with postoperative pain. The findings may promote multimodal rehabilitation concepts including psychological and work-related support. PMID:27243810

  7. Summary of the RHIC Retreat 2008

    SciTech Connect

    Pilat,F.; Brennan, M.; Brown, K.; Fischer, W.; Montag, C.

    2008-08-01

    The main goal of the RHIC Retreat is to review last run's performance and prepare for the next. As always though we also discussed the longer term goals and plans for the facility to put the work in perspective and in the right priority. A straw-man plan for the facility was prepared for the DOE that assumes 30 cryoweek and running 2 species per year. The plan outlines RHIC operations for 2008-2012 and integrates well accelerator and detector upgrades to optimize the physics output with high luminosities. The plans includes guidance from the PAC and has been reviewed by DOE.

  8. Stream temperature response to glacier retreat (Invited)

    NASA Astrophysics Data System (ADS)

    Moore, R. D.

    2013-12-01

    Stream temperature is a fundamental aspect of aquatic habitat, and there has been increasing concern in recent years that climatic change and glacier retreat will result in increased water temperatures, with potentially negative influences on cold and cool water species such as salmonids. A statistical model was developed to predict the maximum weekly average stream temperature based on data from 418 sites located throughout British Columbia, Canada. Catchment-scale glacier coverage was a significant predictor in the model, and example calculations indicate that plausible decreases in glacier coverage over the next few decades have the potential to result in warming that would be sufficient to cause shifts in fish species assemblages. However, this space-for-time substitution rests on assumptions that may not be valid, especially in the context of a changing climate, leading to a need to develop and apply physically based models. Reach-scale energy budget analyses indicate that parameterizations of energy fluxes used in current stream temperature models are not appropriate for steep channels with cascading flow. In particular, the sensible and latent heat fluxes are more efficient than in lower-gradient channels, and the albedo is enhanced by aeration. Over longer time scales, development of riparian forest has the potential to mitigate the effect of glacier retreat in alpine areas by shading the stream, but it may take centuries for functional riparian forest to develop at higher elevation sites.

  9. Does fear of movement mediate the relationship between pain intensity and disability in patients following whiplash injury? A prospective longitudinal study.

    PubMed

    Kamper, Steven J; Maher, Christopher G; Menezes Costa, Luciola da C; McAuley, James H; Hush, Julia M; Sterling, Michele

    2012-01-01

    The aim of this study was to test the capacity of the Fear Avoidance Model to explain the relationship between pain and disability in patients with whiplash-associated disorders. Using the method of Baron and Kenny, we assessed the mediating effect of fear of movement on the cross-sectional and longitudinal relationships between pain and disability. Two hundred and five subjects with neck pain due to a motor vehicle accident provided pain intensity (0 to 10 numerical rating scale), fear of movement (Tampa Scale of Kinesiophobia and Pictorial Fear of Activity Scale) and disability (Neck Disability Index) scores within 4 weeks of their accident, after 3 months, and after 6 months. The analyses were consistent with the Fear Avoidance Model mediating approximately 20% to 40% of the relationship between pain and disability. Contrary to our initial hypothesis, the proportion of the total effect of pain on disability that was mediated by fear of movement did not substantially change as increasing time elapsed after the accident. The proportion mediated was slightly higher when fear of movement was measured by Tampa Scale of Kinesiophobia as compared with Pictorial Fear of Activity Scale. The findings of this study suggest that the Fear Avoidance Model plays a role in explaining a moderate proportion of the relationship between pain and disability after whiplash injury.

  10. Latest Word on Retreat of the West Antarctic Ice Sheet

    NASA Technical Reports Server (NTRS)

    Bindschadler, R.

    2000-01-01

    The West Antarctic ice sheet during the Last Glacial Maximum (LGM) is estimated to have been three times its present volume and to have extended close to the edge of the continental shelf Holocene retreat of this ice sheet in the Ross Sea began between 11,000 and 12,000 years ago. This history implies an average contribution of this ice sheet to sea level of 0.9 mm/a. Evidence of dateable past grounding line positions in the Ross sector are broadly consistent with a linear retreat model. However, inferred rates of retreat for some of these grounding line positions are not consistent with a linear retreat model. More rapid retreat approximately 7600 years ago and possible near-stability in the Ross Sea sector at present suggest a slow rate of initial retreat followed by a more rapid-than-average retreat during the late Holocene, returning to a near-zero rate of retreat currently. This model is also consistent with the mid-Holocene high stand observations of eustatic sea level. Recent compilation of Antarctic bed elevations (BEDMAP) illustrates that the LGM and present grounding lines occur in the shallowest waters, further supporting the model of a middle phase of rapid retreat bracketed by an older and a more recent phase of modest retreat. Extension of these hypotheses into the future make subsequent behavior of the West Antarctic ice sheet more difficult to predict but suggest that if it loses its hold on the present shallow bed, the final retreat of the ice sheet could be very rapid.

  11. COMPARATIVE SEM EVALUATION OF THREE SOLVENTS USED IN ENDODONTIC RETREATMENT: AN EX VIVO STUDY

    PubMed Central

    Scelza, Miriam F. Zaccaro; Coil, Jeffrey M.; Maciel, Ana Carolina de Carvalho; Oliveira, Lílian Rachel L.; Scelza, Pantaleo

    2008-01-01

    This study compared, by scanning electron microscopy (SEM), the efficacy of three solvents on the removal of filling materials from dentinal tubules during endodontic retreatment. Forty human maxillary canines with straight canals were prepared according to a crown-down technique and enlarged to a#30 apical file size, before obturation with gutta-percha and a zinc-oxide-eugenol based sealer. The samples were stored for 3 months before being randomly assigned to four groups: chloroform (n=10), orange oil (n=10), eucalyptol (n=10) and control (n=10). Solvents were applied to a reservoir created on the coronal root third using Gates Glidden drills. The total time for retreatment using the solvents was 5 minutes per tooth. Following retreatment the roots were split longitudinally for SEM evaluation. SEM images were digitized, analyzed using Image ProPlus 4.5 software, and the number of dentinal tubules free of filling material from the middle and apical thirds was recorded. No significant difference was found among the solvent groups regarding the number of dentinal tubules free of root filling remnants in the middle and apical root thirds (p>0.05). However, the control group had fewer dentinal tubules free of filling material (p<0.05). Under the tested conditions, it may be concluded that there was no significant difference among the solvents used to obtain dentinal tubules free of filling material remnants. PMID:19089285

  12. Change on psychological scales following Buddhist and Roman Catholic retreats.

    PubMed

    Tori, C D

    1999-02-01

    Orthogonal contrasts of Adjective Checklist pretest-posttest change scores obtained from adolescents who attended three-day Buddhist or Roman Catholic retreats (n = 204) and no treatment control participants (n = 102) indicated those who attended had higher change scores and greater change occurred among those attending the Buddhist meditation retreat.

  13. Developer's Concerns about Staff Retreat Create Opportunity and Obligation

    ERIC Educational Resources Information Center

    Killion, Joellen

    2004-01-01

    This article deals with a staff developer's concerns about Bill Stewart's staff retreat, and how these concerns create opportunity and obligation. The author presents views from a superintendent and two staff developers on the staff retreat. Aside from these, the author talks about a superintendent named Darlene Preston, and her course of action.…

  14. Academic Writing Retreat: A Time for Rejuvenated and Focused Writing

    ERIC Educational Resources Information Center

    Swaggerty, Elizabeth A.; Atkinson, Terry S.; Faulconer, Johna L.; Griffith, Robin R.

    2011-01-01

    The purpose of this article is to describe the impact of a three-day academic writing retreat on the writing lives of four female university faculty members. Goals of the retreat included rejuvenating their writing lives, focusing their research agendas, improving their writing, and engaging in concentrated blocks of writing and collaborative…

  15. Quality of Life and Survival Outcome for Patients With Nasopharyngeal Carcinoma Receiving Three-Dimensional Conformal Radiotherapy vs. Intensity-Modulated Radiotherapy-A Longitudinal Study

    SciTech Connect

    Fang, F.-M. Chien, C.-Y.; Tsai, W.-L.; Chen, H.-C.; Hsu, H.-C.; Lui, C.-C.; Huang, T.-L.

    2008-10-01

    Purpose: To investigate the changes of quality of life (QoL) and survival outcomes for patients with nasopharyngeal carcinoma (NPC) treated by three-dimensional conformal radiotherapy (3D-CRT) vs. intensity-modulated radiotherapy (IMRT). Methods and Materials: Two hundred and three newly diagnosed NPC patients, who were curatively treated by 3D-CRT (n = 93) or IMRT (n = 110) between March 2002 and July 2004, were analyzed. The distributions of clinical stage according to American Joint Committee on Cancer 1997 were I: 15 (7.4%), II: 78 (38.4%), III: 74 (36.5%), and IV: 36 (17.7%). QoL was longitudinally assessed by the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and the EORTC QLQ-H and N35 questionnaires at the five time points: before RT, during RT (36 Gy), and 3 months, 12 months, and 24 months after RT. Results: The 3-year locoregional control, metastasis-free survival, and overall survival rates were 84.8%, 76.7%, and 81.7% for the 3D-CRT group, respectively, compared with 84.2%, 82.6%, and 85.4% for the IMRT group (p value > 0.05). A general trend of maximal deterioration in most QoL scales was observed during RT, followed by a gradual recovery thereafter. There was no significant difference in most scales between the two groups at each time point. The exception was that patients treated by IMRT had a both statistically and clinically significant improvement in global QoL, fatigue, taste/smell, dry mouth, and feeling ill at the time point of 3 months after RT. Conclusions: The potential advantage of IMRT over 3D-CRT in treating NPC patients might occur in QoL outcome during the recovery phase of acute toxicity.

  16. Calculating lunar retreat rates using tidal rhythmites

    USGS Publications Warehouse

    Kvale, E.P.; Johnson, H.W.; Sonett, C.P.; Archer, A.W.; Zawistoski, A.N.N.

    1999-01-01

    Tidal rhythmites are small-scale sedimenta??r}- structures that can preserve a hierarchy of astronomically induced tidal periods. They can also preserve a record of periodic nontidal sedimentation. If properly interpreted and understood, tidal rhjthmites can be an important component of paleoastronomy and can be used to extract information on ancient lunar orbital dynamics including changes in Earth-Moon distance through geologic time. Herein we present techniques that can be used to calculate ancient Earth-Moon distances. Each of these techniques, when used on a modern high-tide data set, results in calculated estimates of lunar orbital periods and an EarthMoon distance that fall well within 1 percent of the actual values. Comparisons to results from modern tidal data indicate that ancient tidal rhythmite data as short as 4 months can provide suitable estimates of lunar orbital periods if these tidal records are complete. An understanding of basic tidal theory allows for the evaluation of completeness of the ancient tidal record as derived from an analysis of tidal rhythmites. Utilizing the techniques presented herein, it appears from the rock record that lunar orbital retreat slowed sometime during the midPaleozoic. Copyright ??1999, SEPM (Society for Sedimentary Geology).

  17. Seaweed communities in retreat from ocean warming.

    PubMed

    Wernberg, Thomas; Russell, Bayden D; Thomsen, Mads S; Gurgel, C Frederico D; Bradshaw, Corey J A; Poloczanska, Elvira S; Connell, Sean D

    2011-11-01

    In recent decades, global climate change [1] has caused profound biological changes across the planet [2-6]. However, there is a great disparity in the strength of evidence among different ecosystems and between hemispheres: changes on land have been well documented through long-term studies, but similar direct evidence for impacts of warming is virtually absent from the oceans [3, 7], where only a few studies on individual species of intertidal invertebrates, plankton, and commercially important fish in the North Atlantic and North Pacific exist. This disparity of evidence is precarious for biological conservation because of the critical role of the marine realm in regulating the Earth's environmental and ecological functions, and the associated socioeconomic well-being of humans [8]. We interrogated a database of >20,000 herbarium records of macroalgae collected in Australia since the 1940s and documented changes in communities and geographical distribution limits in both the Indian and Pacific Oceans, consistent with rapid warming over the past five decades [9, 10]. We show that continued warming might drive potentially hundreds of species toward and beyond the edge of the Australian continent where sustained retreat is impossible. The potential for global extinctions is profound considering the many endemic seaweeds and seaweed-dependent marine organisms in temperate Australia.

  18. Patient-Reported Voice and Speech Outcomes After Whole-Neck Intensity Modulated Radiation Therapy and Chemotherapy for Oropharyngeal Cancer: Prospective Longitudinal Study

    SciTech Connect

    Vainshtein, Jeffrey M.; Griffith, Kent A.; Feng, Felix Y.; Vineberg, Karen A.; Chepeha, Douglas B.; Eisbruch, Avraham

    2014-08-01

    Purpose: To describe voice and speech quality changes and their predictors in patients with locally advanced oropharyngeal cancer treated on prospective clinical studies of organ-preserving chemotherapy–intensity modulated radiation therapy (chemo-IMRT). Methods and Materials: Ninety-one patients with stage III/IV oropharyngeal cancer were treated on 2 consecutive prospective studies of definitive chemoradiation using whole-field IMRT from 2003 to 2011. Patient-reported voice and speech quality were longitudinally assessed from before treatment through 24 months using the Communication Domain of the Head and Neck Quality of Life (HNQOL-C) instrument and the Speech question of the University of Washington Quality of Life (UWQOL-S) instrument, respectively. Factors associated with patient-reported voice quality worsening from baseline and speech impairment were assessed. Results: Voice quality decreased maximally at 1 month, with 68% and 41% of patients reporting worse HNQOL-C and UWQOL-S scores compared with before treatment, and improved thereafter, recovering to baseline by 12-18 months on average. In contrast, observer-rated larynx toxicity was rare (7% at 3 months; 5% at 6 months). Among patients with mean glottic larynx (GL) dose ≤20 Gy, >20-30 Gy, >30-40 Gy, >40-50 Gy, and >50 Gy, 10%, 32%, 25%, 30%, and 63%, respectively, reported worse voice quality at 12 months compared with before treatment (P=.011). Results for speech impairment were similar. Glottic larynx dose, N stage, neck dissection, oral cavity dose, and time since chemo-IMRT were univariately associated with either voice worsening or speech impairment. On multivariate analysis, mean GL dose remained independently predictive for both voice quality worsening (8.1%/Gy) and speech impairment (4.3%/Gy). Conclusions: Voice quality worsening and speech impairment after chemo-IMRT for locally advanced oropharyngeal cancer were frequently reported by patients, underrecognized by clinicians, and

  19. How fast do gully headcuts retreat?

    NASA Astrophysics Data System (ADS)

    Vanmaercke, Matthias; Poesen, Jean

    2015-04-01

    Gullies can be a dominant sediment source at field and catchment scales. Over the past decades, several studies have been conducted that quantify gully headcut retreat (GHR) in different environments. Although this led to important site-specific and regional insights, the overall importance of this erosion process or the factors that control it at a global scale remain poorly understood. This study aims to bridge this gap by conducting a meta-analysis of measured GHR rates worldwide. Through an extensive literature review, GHR rates for ca. 900 individual actively retreating gullies (comprising a total measuring period of > 19 000 years) from more than 50 study areas worldwide have been compiled. Each GHR rate was measured by means of repeated field surveys and/or analyses of aerial photographs over a period of at least one year. The collected data shows a very large variability, both in terms of gully dimensions (cross-sectional areas ranging between 0.11 and 816 m² with a median of 4 m²) and GHR rates (ranging between 0.003 and 47 000 m³/y with a median of 2.2 m³/y). Linear GHR rates vary between 0.01 and 70 m/y (median: 0.82 m/y). By means of statistical analyses for a subset of 689 gullies with a known contributing area, we explored which factors are most relevant in explaining the observed 6 orders of magnitudes of variation in volumetric GHR rates. Results show that measured GHR rates are significantly correlated to the runoff contributing area of the gully (r² = 0.13) and the average rainfall depth on a rainy day (i.e. the long-term average annual rainfall depth divided by the average number of rainy days; r² = 0.39). Combined, these two factors explained 57% of the observed variability in average GHR rates. Other factors (e.g. land use or soil type) showed no significant correlation with the observed GHR rates. This may be attributed to the uncertainties associated with accurately quantifying these factors. In addition, a large part of the remaining

  20. Rituximab Retreatment for Low-Tumor Burden Follicular Lymphoma

    Cancer.gov

    A summary of results from a randomized clinical trial of patients with low–tumor burden follicular lymphoma that compared maintenance therapy with rituximab versus retreatment with rituximab only when there was evidence of disease progression.

  1. Climate change and glacier retreat drive shifts in an Antarctic benthic ecosystem.

    PubMed

    Sahade, Ricardo; Lagger, Cristian; Torre, Luciana; Momo, Fernando; Monien, Patrick; Schloss, Irene; Barnes, David K A; Servetto, Natalia; Tarantelli, Soledad; Tatián, Marcos; Zamboni, Nadia; Abele, Doris

    2015-11-01

    The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last 50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largest ice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasingly predicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species being benthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblage level are unknown. This is probably due to the scarcity of baselines against which to assess change. We performed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure and environmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic community that can be linked to ongoing climate change. However, rather than temperature as the primary factor, we highlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. The sudden shift from a "filter feeders-ascidian domination" to a "mixed assemblage" suggests that thresholds (for example, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of the changes, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the current scenario of glacier retreat, and attention needs to be paid to its effects along the AP. PMID:26702429

  2. Climate change and glacier retreat drive shifts in an Antarctic benthic ecosystem.

    PubMed

    Sahade, Ricardo; Lagger, Cristian; Torre, Luciana; Momo, Fernando; Monien, Patrick; Schloss, Irene; Barnes, David K A; Servetto, Natalia; Tarantelli, Soledad; Tatián, Marcos; Zamboni, Nadia; Abele, Doris

    2015-11-01

    The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last 50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largest ice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasingly predicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species being benthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblage level are unknown. This is probably due to the scarcity of baselines against which to assess change. We performed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure and environmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic community that can be linked to ongoing climate change. However, rather than temperature as the primary factor, we highlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. The sudden shift from a "filter feeders-ascidian domination" to a "mixed assemblage" suggests that thresholds (for example, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of the changes, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the current scenario of glacier retreat, and attention needs to be paid to its effects along the AP.

  3. Climate change and glacier retreat drive shifts in an Antarctic benthic ecosystem

    PubMed Central

    Sahade, Ricardo; Lagger, Cristian; Torre, Luciana; Momo, Fernando; Monien, Patrick; Schloss, Irene; Barnes, David K. A.; Servetto, Natalia; Tarantelli, Soledad; Tatián, Marcos; Zamboni, Nadia; Abele, Doris

    2015-01-01

    The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last 50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largest ice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasingly predicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species being benthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblage level are unknown. This is probably due to the scarcity of baselines against which to assess change. We performed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure and environmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic community that can be linked to ongoing climate change. However, rather than temperature as the primary factor, we highlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. The sudden shift from a “filter feeders–ascidian domination” to a “mixed assemblage” suggests that thresholds (for example, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of the changes, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the current scenario of glacier retreat, and attention needs to be paid to its effects along the AP. PMID:26702429

  4. A week-long meditation retreat decouples behavioral measures of the alerting and executive attention networks.

    PubMed

    Elliott, James C; Wallace, B Alan; Giesbrecht, Barry

    2014-01-01

    PREVIOUS STUDIES HAVE EXAMINED THE INFLUENCE OF MEDITATION ON THREE FUNCTIONALLY DIFFERENT COMPONENTS OF ATTENTION: executive control, alerting, and orienting. These studies have consistently found that meditation training improves both executive attention and alerting, but there has not been a consistent and clear effect of meditation training on orienting. In addition, while previous studies have shown that the functional coupling of the alerting and executive networks increases the processing of task irrelevant stimuli, it is unknown if participating in a meditation retreat can decouple these components of attention and lead to improved performance. The current study investigated the influence of a week-long intensive meditation retreat on three components of attention by randomly assigning participants to either pre- or postretreat testing groups. A modified attention network test (ANT) was used. Executive attention was measured as the difference in response time (RT) between congruent and incongruent task irrelevant flankers (conflict effect). Reflexive and volitional orienting were measured by manipulating cue validity and stimulus onset asynchrony (SOA). The coupling of executive attention and alerting was measured by examining flanker interference as a function of the SOA of an alerting cue. The meditation retreat improved task based indices of executive attention, but not reflexive or volitional orienting. There was clear behavioral evidence of coupling between executive attention and alerting in the preretreat group, as the conflict effect peaked when an alerting cue was presented 300 ms before the target. Importantly, there was no increase in the conflict effect for the postretreat group. This is consistent with the notion that the retreat decoupled the executive and alerting networks. These results suggest that previously reported improvements in the executive and alerting networks after meditation training might be mediated by the same underlying

  5. Endodontic retreatment. Aspects of decision making and clinical outcome.

    PubMed

    Kvist, T

    2001-01-01

    Epidemiological surveys have reported that 25%-35% of root filled teeth are associated with periapical radiolucencies. Descriptive studies have demonstrated that clinicians' decision making regarding such teeth are subject to substantial variation. A coherent model to explain the observed variation has not been produced. In the present thesis a "Praxis Concept theory" was proposed. The theory suggests that dentists perceive periapical lesions of varying sizes as different stages on a continuous health scale. Interindividual variations can then be regarded as the result of the choice of different cut-off points on the continuum for prescribing retreatment. In the present study experiments among novice and expert decision makers gave evidence in favour of the theory. Data also suggested that the choice of retreatment criterion is affected by values, costs of retreatment and technical quality of original treatment. From a prescriptive point of view, the presence of a persistent periapical radiolucency has often been used as a criterion of endodontic "failure" and as an indication for endodontic retreatment. As an alternative decision strategy, the use of decision analysis has been proposed. Logical display of decision alternatives, values of probabilities, utility values (U-values) of the different outcomes and calculation of optimal decision strategy are features of this theory. The implementation of this approach is impeded by the uncertainty of outcome probabilities and lack of investigations concerning U-values. U-values of two periapical health states in root filled teeth (with and without a periapical lesion respectively) were investigated in a group of 82 dental students and among 16 Swedish endodontists. Two methods were used to elicit U-values: Standard gamble and Visual Analogue Scale. Large interindividual variation for both health states were recorded. The difference in U-values between the two health states was found to be statistically significant

  6. Characteristics and Treatment Outcomes of Retreatment Tuberculosis Patients in Benin.

    PubMed

    Ade, Serge; Adjibodé, Omer; Wachinou, Prudence; Toundoh, Narcisse; Awanou, Bérénice; Agodokpessi, Gildas; Affolabi, Dissou; Adè, Gabriel; Harries, Anthony D; Anagonou, Séverin

    2016-01-01

    Objective. To determine among retreatment tuberculosis patients in Benin baseline characteristics, culture, and drug sensitivity testing (DST) results and treatment outcomes. Materials and Methods. A retrospective national cohort study of all retreatment tuberculosis patients in Benin in 2013 using registers and treatment cards. Results. Of 3957 patients with tuberculosis, 241 (6%) were retreatment cases. Compared to new pulmonary bacteriologically confirmed tuberculosis (NPBCT) patients, there were significantly higher numbers of males (P = 0.04), patients from "Atlantique-Littoral" (P = 0.006), patients aged 45-64 years (P = 0.007), and HIV-positive patients (P = 0.04) among those retreated. Overall, 171 (71%) patients submitted sputum for DST, of whom (163) 95% were positive for Mycobacterium tuberculosis on Xpert MTB/RIF and/or culture and 17 (10%) were rifampicin resistant (9 with MDR-TB and 8 monoresistant to rifampicin). For those without MDR-TB (n = 224), treatment success was 93%. Worse outcomes occurred in those with unknown HIV status (RR: 0.27; 0.05-1.45; P < 0.01) while better outcomes occurred in those who relapsed (RR: 1.06, 95 CI: 1.02-1.10, P = 0.04). Conclusion. In 2013, a high proportion of retreatment patients received DST. Treatment success was good although more needs to be done to systematically increase the final follow-up smear examination. Reasons of high losses to follow-up from "Oueme-Plateau" should be investigated. PMID:27110400

  7. The Relationship between Intensity and Breadth of After-School Program Participation and Academic Achievement: Evidence from a Short-Term Longitudinal Study

    ERIC Educational Resources Information Center

    Springer, Ken; Diffily, Deborah

    2012-01-01

    We explored the extent to which intensity and breadth of participation in an after-school program (ASP) predicted academic achievement, as measured by changes in grades and attendance. The sample comprised 719 2nd-grade through 8th-grade Boys and Girls Clubs of Greater Dallas members during the 2009-2010 academic year. With respect to intensity,…

  8. The Time It Takes: A Longitudinal Study of the 2003 Cohort of Students Eligible to Transfer to a BC Research Intensive University

    ERIC Educational Resources Information Center

    Lavin, Tracy

    2011-01-01

    The BC Transfer System allows students to attend public colleges, institutes and teaching intensive universities (i.e., Central Data Warehouse or CDW reporting institutions) throughout the province where they accumulate credits which they can transfer to research intensive universities and use to fulfill their degree requirements. The Student…

  9. Endodontic retreatment in case of failure. Case report.

    PubMed

    Mărgărit, Ruxandra; Andrei, Oana Celia

    2011-01-01

    In medical practice, clinicians come across an increased number of endodontic treatments, which, like other dental treatments, can fail. The increase in the number of endodontic treatment resulted in an increased number of failures, their management raising complex and serious endodontic problems. The endodontic retreatment of a failure is required by the increased desire to preserve the tooth on the dental arch, thus preventing the need for dental extraction that may have adverse consequences in terms of functional and psychological effect on patients. This article presents two clinical cases that required endodontic retreatment in order to avoid the complications that could ultimately require tooth extraction. The teeth in question (a mandibular first molar and an upper central incisor) having a special importance, and a physiognomic role, the endodontic retreatment consisted in covering them in porcelain fused to the metal crowns. PMID:22046813

  10. Ocean forcing of glacier retreat in the western Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Cook, A. J.; Holland, P. R.; Meredith, M. P.; Murray, T.; Luckman, A.; Vaughan, D. G.

    2016-07-01

    In recent decades, hundreds of glaciers draining the Antarctic Peninsula (63° to 70°S) have undergone systematic and progressive change. These changes are widely attributed to rapid increases in regional surface air temperature, but it is now clear that this cannot be the sole driver. Here, we identify a strong correspondence between mid-depth ocean temperatures and glacier-front changes along the ~1000-kilometer western coastline. In the south, glaciers that terminate in warm Circumpolar Deep Water have undergone considerable retreat, whereas those in the far northwest, which terminate in cooler waters, have not. Furthermore, a mid-ocean warming since the 1990s in the south is coincident with widespread acceleration of glacier retreat. We conclude that changes in ocean-induced melting are the primary cause of retreat for glaciers in this region.

  11. Ocean forcing of glacier retreat in the western Antarctic Peninsula.

    PubMed

    Cook, A J; Holland, P R; Meredith, M P; Murray, T; Luckman, A; Vaughan, D G

    2016-07-15

    In recent decades, hundreds of glaciers draining the Antarctic Peninsula (63° to 70°S) have undergone systematic and progressive change. These changes are widely attributed to rapid increases in regional surface air temperature, but it is now clear that this cannot be the sole driver. Here, we identify a strong correspondence between mid-depth ocean temperatures and glacier-front changes along the ~1000-kilometer western coastline. In the south, glaciers that terminate in warm Circumpolar Deep Water have undergone considerable retreat, whereas those in the far northwest, which terminate in cooler waters, have not. Furthermore, a mid-ocean warming since the 1990s in the south is coincident with widespread acceleration of glacier retreat. We conclude that changes in ocean-induced melting are the primary cause of retreat for glaciers in this region. PMID:27418507

  12. Comparison of the amount of apical debris extrusion associated with different retreatment systems and supplementary file application during retreatment process

    PubMed Central

    Çiçek, Ersan; Koçak, Mustafa Murat; Koçak, Sibel; Sağlam, Baran Can

    2016-01-01

    Background: The type of instrument affects the amount of debris extruded. The aim of this study was to compare the effect of retreatment systems and supplementary file application on the amount of apical debris extrusion. Materials and Methods: Forty-eight extracted mandibular premolars with a single canal and similar length were selected. The root canals were prepared with the ProTaper Universal system with a torque-controlled engine. The root canals were dried and were obturated using Gutta-percha and sealer. The specimens were randomly divided into four equal groups according to the retreatment procedures (Group 1, Mtwo retreatment files; Group 2, Mtwo retreatment files + Mtwo rotary file #30 supplementary file; Group 3, ProTaper Universal retreatment (PTUR) files; and Group 4, PTUR files + ProTaper F3 supplementary file). The extruded debris during instrumentation were collected into preweighed Eppendorf tubes. The amount of apically extruded debris was calculated by subtracting the initial weight of the tube from the final weight. Three consecutive weights were obtained for each tube. Results: No statistically significant difference was found in the amount of apically extruded debris between Groups 1 and 3 (P = 0.590). A significant difference was observed between Groups 1 and 2 (P < 0.05), and between Groups 3 and 4 (P < 0.05). Conclusions: The use of supplementary file significantly increased the amount of apically extruded debris. PMID:27563185

  13. Is rate of glacial retreat accelerated in Indian Himalaya? (Invited)

    NASA Astrophysics Data System (ADS)

    Kulkarni, A. V.

    2013-12-01

    The Himalaya has one of the largest concentration of glaciers and rivers like Indus, Ganga and Bramhputra originate from this region. The snow and glacier melt is an important source of water for these rivers. However, this source of water may get affected in the near future due to changes in the cryosphere. Therefore, retreat of Himalayan glaciers are discussed extensively in scientific and public forums in India. Conventionally health of glaciers is assessed using changes in glacial length, as it is widely measured. However changes in glacial length and loss in areal extent near terminus needs to be interpreted carefully, as these changes can be influenced by numerous terrain and climatically sensitive parameters. The terrain parameters which can influence glacial retreat are slope, area altitude distribution, debris cover and orientation. In addition, climatically sensitive parameters like mass balance, glacial lakes and black carbon can also influence glacier retreat. These multiple influences can produce a complex pattern of glacial retreat. In this paper long-term glacier retreat in three river basins in the Indian Himalaya as Tista, Baspa and Parbati will be discussed. These basins are located in different climatically sensitive regions and each basin has unique dominant process of mass wasting. In addition to terrain parameters, influence of process like formation and expansion of moraine dammed lakes in Tista basin, deposition of black carbon on accumulation area in Baspa basin and debris cover in Parbati basin will also be discussed. This will provide understanding on varying influence of different mass wasting processes on glacial retreat during last five decades in the Indian Himalaya.

  14. Quantifying global warming from the retreat of glaciers

    SciTech Connect

    Oerlemans, J. )

    1994-04-08

    Records of glacier fluctuations compiled by the World Glacier Monitoring Service can be used to derive an independent estimate of global warming during the last 100 years. Records of different glaciers are made comparable by a two-step scaling procedure; one allowing for differences in glacier geometry, the other for differences in climate sensitivity. The retreat of glaciers during the last 100 years appears to be coherent over the globe. On the basis of modeling of the climate sensitivity of glaciers, the observed glacier retreat can be explained by a linear warming trend of 0.66 kelvin per century.

  15. LONGITUDINAL SOLUTIONS IN RHIC.

    SciTech Connect

    BLASKIEWICZ,M.BRENNAN,J.M.FISCHER,W.CAMERON,P.WEI,J.LUQUE,A.SCHAMEL,H.

    2003-05-12

    Stable, coherent, longitudinal oscillations have been observed in the RHIC accelerator. Within the context of perturbation theory, the beam parameters and machine impedance suggest these oscillations should be Landau damped. When nonlinear effects are included, long lived, stable oscillations become possible for low intensity beams. Simulations and theory are compared with data.

  16. Dendrogeomorphic approach to estimating slope retreat, Maxey Flats, Kentucky

    NASA Astrophysics Data System (ADS)

    Hupp, Cliff R.; Carey, William P.

    1990-07-01

    A dendrogeomorphic study of slope retreat was conducted at the Maxey Flats nuclear-waste disposal site in northeastern Kentucky. Tree roots exposed by surface lowering were used as an indicator of ground surface at the time of germination. The amount of lowering was measured and divided by tree-ring-determined tree age. Surface lowering and slope degradation rates were estimated for three slopes below waste-burial trenches and compared with data obtained from sediment troughs and erosion frames at the site. Mean rates of slope retreat ranged from 1.92 to 3.16 mm/yr. Sediment-trough results are two to three orders of magnitude less than dendrogeomorphic and erosion-frame estimates of slope degradation, which suggests that piping and solution-weathering processes may be important in slope degradation. Slope aspect and declivity may be important factors affecting retreat of slopes with a uniform lithology. Dendrogeomorphic techniques provide results comparable to those in the literature and offer a rapid method for estimating slope retreat that integrates slope processes over many years.

  17. Partner Choice and the Differential Retreat from Marriage

    ERIC Educational Resources Information Center

    Schoen, Robert; Cheng, Yen-Hsin Alice

    2006-01-01

    The contemporary retreat from marriage in the United States has had a differential impact across socioeconomic and racial groups. Here, 1990 marriage rates and propensities for Virginia, North Carolina, and Wisconsin are analyzed regarding (a) the likelihood that persons in different groups ever marry and (b) patterns of partner choice with…

  18. Scientists Discover New Possibilities at Scientific Investigators Retreat | Poster

    Cancer.gov

    By Nancy Parrish, Staff Writer; photos by Richard Frederickson, Staff Photographer Scientists who attended the 2015 NCI Intramural Scientific Investigators Retreat on Jan. 13 had a chance to discuss research results with other investigators from across the National Cancer Institute. And this year, they could also explore new possibilities for the future of their research.

  19. Promoting Writing for Research: The "Writing Retreat" Model

    ERIC Educational Resources Information Center

    Singh, R. J.

    2012-01-01

    Research papers take a long time to write and in an academic environment where the "publish or perish" clause applies, writing retreats are a way of creating time and space to write academic articles in a concentrated period of time. This article examines ways in which academics can write more articles for publication. In particular it focuses on…

  20. Jumpstarting Junior Faculty Motivation and Performance with Focused Writing Retreats

    ERIC Educational Resources Information Center

    Girardeau, Laura; Rud, A. G.; Trevisan, Michael S.

    2014-01-01

    Faculty members are critical assets to universities, and large losses to institutions occur if they are not successful. Although institutions value publications and grants in the tenure process, newer professors receive little guidance in writing for these endeavors. Faculty writing retreats help apprentice professors in the craft of writing;…

  1. Exploring the Effectiveness of a Retreat Method for Extension Staff

    ERIC Educational Resources Information Center

    Worker, Steven M.; Hill, Russell D.; Miller, JoLynn C.; Go, Charles G.; Boyes, Rita J.

    2015-01-01

    The California 4-H Association hosted two retreats to support its members with goals of balancing professional development with intentional relationship building. Evaluations demonstrated that staff found the intentional balance of time spent in unstructured, semi-structured, and structured time offered opportunities to grow professionally while…

  2. Effects of errors in velocity tilt on maximum longitudinal compression during neutralized drift compression of intense beam pulses: I. general description

    SciTech Connect

    Kaganovich, Igor D.; Massidda, Scottt; Startsev, Edward A.; Davidson, Ronald C.; Vay, Jean-Luc; Friedman, Alex

    2012-06-21

    Neutralized drift compression offers an effective means for particle beam pulse compression and current amplification. In neutralized drift compression, a linear longitudinal velocity tilt (head-to-tail gradient) is applied to the non-relativistic beam pulse, so that the beam pulse compresses as it drifts in the focusing section. The beam current can increase by more than a factor of 100 in the longitudinal direction. We have performed an analytical study of how errors in the velocity tilt acquired by the beam in the induction bunching module limit the maximum longitudinal compression. It is found that the compression ratio is determined by the relative errors in the velocity tilt. That is, one-percent errors may limit the compression to a factor of one hundred. However, a part of the beam pulse where the errors are small may compress to much higher values, which are determined by the initial thermal spread of the beam pulse. It is also shown that sharp jumps in the compressed current density profile can be produced due to overlaying of different parts of the pulse near the focal plane. Examples of slowly varying and rapidly varying errors compared to the beam pulse duration are studied. For beam velocity errors given by a cubic function, the compression ratio can be described analytically. In this limit, a significant portion of the beam pulse is located in the broad wings of the pulse and is poorly compressed. The central part of the compressed pulse is determined by the thermal spread. The scaling law for maximum compression ratio is derived. In addition to a smooth variation in the velocity tilt, fast-changing errors during the pulse may appear in the induction bunching module if the voltage pulse is formed by several pulsed elements. Different parts of the pulse compress nearly simultaneously at the target and the compressed profile may have many peaks. The maximum compression is a function of both thermal spread and the velocity errors. The effects of the

  3. Characteristics and Treatment Outcomes of Retreatment Tuberculosis Patients in Benin

    PubMed Central

    Ade, Serge; Adjibodé, Omer; Wachinou, Prudence; Toundoh, Narcisse; Awanou, Bérénice; Agodokpessi, Gildas; Affolabi, Dissou; Adè, Gabriel; Harries, Anthony D.; Anagonou, Séverin

    2016-01-01

    Objective. To determine among retreatment tuberculosis patients in Benin baseline characteristics, culture, and drug sensitivity testing (DST) results and treatment outcomes. Materials and Methods. A retrospective national cohort study of all retreatment tuberculosis patients in Benin in 2013 using registers and treatment cards. Results. Of 3957 patients with tuberculosis, 241 (6%) were retreatment cases. Compared to new pulmonary bacteriologically confirmed tuberculosis (NPBCT) patients, there were significantly higher numbers of males (P = 0.04), patients from “Atlantique-Littoral” (P = 0.006), patients aged 45–64 years (P = 0.007), and HIV-positive patients (P = 0.04) among those retreated. Overall, 171 (71%) patients submitted sputum for DST, of whom (163) 95% were positive for Mycobacterium tuberculosis on Xpert MTB/RIF and/or culture and 17 (10%) were rifampicin resistant (9 with MDR-TB and 8 monoresistant to rifampicin). For those without MDR-TB (n = 224), treatment success was 93%. Worse outcomes occurred in those with unknown HIV status (RR: 0.27; 0.05–1.45; P < 0.01) while better outcomes occurred in those who relapsed (RR: 1.06, 95 CI: 1.02–1.10, P = 0.04). Conclusion. In 2013, a high proportion of retreatment patients received DST. Treatment success was good although more needs to be done to systematically increase the final follow-up smear examination. Reasons of high losses to follow-up from “Oueme-Plateau” should be investigated. PMID:27110400

  4. Longitudinal laser ion acceleration in low density targets: experimental optimization on the Titan laser facility and numerical investigation of the ultra-high intensity limit

    NASA Astrophysics Data System (ADS)

    d'Humières, E.; Chen, S.; Lobet, Mathieu; Sciscio, M.; Antici, Patrizio; Bailly-Grandvaux, Mathieu; Gangolf, Thomas; Revet, Guilhem; Santos, Joao J.; Schroer, Anna-Marie; Willi, O.; Tikhonchuk, Vladimir T.; Pepin, Henri; Fuchs, Julien

    2015-05-01

    Recent theoretical and experimental studies suggest the possibility of enhancing the efficiency and ease of laser acceleration of protons and ions using underdense or near critical plasmas through electrostatic shocks. Very promising results were recently obtained in this regime. In these experiments, a first ns pulse was focused on a thin target to explode it and a second laser with a high intensity was focused on the exploded foil. The delay between two lasers allowed to control the density gradient seen by the second laser pulse. The transition between various laser ion acceleration regimes depending on the density gradient length was studied. With a laser energy of a few Joules, protons with energies close to the energies of TNSA accelerated protons were obtained for various exploded foils configurations. In the high energy regime (~180 J), protons with energies significantly higher than the ones of TNSA accelerated protons were obtained when exploding the foil while keeping a good beam quality. These results demonstrate that low-density targets are promising candidates for an efficient proton source that can be optimized by choosing appropriate plasma conditions. New experiments were also performed in this regime with gas jets. Scaling shock acceleration in the low density regime to ultra high intensities is a challenge as radiation losses and electron positron pair production change the optimization of the shock process. Using large-scale Particle-In-Cell simulations, the transition to this regime in which intense beams of relativistic ions can be produced is investigated.

  5. Intense monochromatic terahertz electromagnetic waves from coherent GaAs-like longitudinal optical phonons in (11n)-oriented GaAs/In0.1Al0.9As strained multiple quantum wells

    NASA Astrophysics Data System (ADS)

    Takeuchi, Hideo; Asai, Souta; Tsuruta, Syuichi; Nakayama, Masaaki

    2012-06-01

    We demonstrate that, in (11n)-oriented GaAs/In0.1Al0.9As strained multiple quantum wells, the terahertz electromagnetic wave from the coherent GaAs-like longitudinal optical (LO) phonon is enhanced by a piezoelectric field originating from a tensile strain in the GaAs layer. The presence of the tensile strain is confirmed using Raman scattering spectroscopy. The Fourier power spectrum of the terahertz waveform shows that the intensity of the terahertz band of the coherent GaAs-like LO phonon increases as the index n approaches 1. The amplitude of the GaAs-like LO phonon is proportional to the piezoelectric field in the strained GaAs layer.

  6. Concise, intensive or longitudinal medical education courses, which is more effective in perceived self-efficacy and development of faculty members?

    PubMed Central

    Mojtahedzadeh, Rita; Mohammadi, Aeen

    2016-01-01

    Background: Teachers’ self-efficacy and development may be conceptualized as their beliefs in their own ability to plan, organize and carry out activities that are required to attain educational goals. In this study, we examined the effect of different medical education training courses (six-day, one- month short- term and sixmonth long- term courses) on perceived self-efficacy and development. Methods: This before-after quasi-experimental study was performed on 39 faculty members of Tehran University of Medical Sciences who participated in faculty development courses in 2013. We used valid and reliable scales to measure their perceived self-efficacy and empowerment. Results: The results revealed a significant increase in faculty members’ perceived self-efficacy in pre and posttests in one-month and six-month courses, but no significant difference was found in the six-day course (p=0.004, p<0.001 and p=0.235, respectively). These results were the same for perceived empowerment (p<0.001, p<0.001 and p=0.716 for one-month, six-month and six-day courses, respectively). A significant difference was detected in perceived self-efficacy and participant empowerment components based on the training course (p=0.005; Wilk's Λ=0.345, Partial η2=0.413). Conclusion: This study revealed that long- term courses were more effective than the short- term ones. Thus, longitudinal courses are recommended for more effectiveness. PMID:27683643

  7. Concise, intensive or longitudinal medical education courses, which is more effective in perceived self-efficacy and development of faculty members?

    PubMed Central

    Mojtahedzadeh, Rita; Mohammadi, Aeen

    2016-01-01

    Background: Teachers’ self-efficacy and development may be conceptualized as their beliefs in their own ability to plan, organize and carry out activities that are required to attain educational goals. In this study, we examined the effect of different medical education training courses (six-day, one- month short- term and sixmonth long- term courses) on perceived self-efficacy and development. Methods: This before-after quasi-experimental study was performed on 39 faculty members of Tehran University of Medical Sciences who participated in faculty development courses in 2013. We used valid and reliable scales to measure their perceived self-efficacy and empowerment. Results: The results revealed a significant increase in faculty members’ perceived self-efficacy in pre and posttests in one-month and six-month courses, but no significant difference was found in the six-day course (p=0.004, p<0.001 and p=0.235, respectively). These results were the same for perceived empowerment (p<0.001, p<0.001 and p=0.716 for one-month, six-month and six-day courses, respectively). A significant difference was detected in perceived self-efficacy and participant empowerment components based on the training course (p=0.005; Wilk's Λ=0.345, Partial η2=0.413). Conclusion: This study revealed that long- term courses were more effective than the short- term ones. Thus, longitudinal courses are recommended for more effectiveness.

  8. New Insights into Antarctic Ice-Sheet Retreat During the Last Sea-Level Rise

    NASA Astrophysics Data System (ADS)

    Weber, M. E.; Kuhn, G.; Clark, P. U.; Sprenk, D.

    2010-12-01

    Reconstruction of the last global sea level rise faces uncertainties because only a few robust results are available for Antarctic ice sheets. Modeling studies reconstruct a late ice-sheet retreat starting around 12 ka BP and ending around 7 ka BP with a large impact of an unstable West Antarctic Ice Sheet (WAIS) and a small impact of a stable East Antarctic Ice Sheet (EAIS). However, two regions in the Atlantic sector of the Southern Ocean provide evidence that Antarctica responded much earlier and possibly provided a significant contribution to the last sea-level rise. On the continental slope of the southeastern Weddell Sea, seven Polarstern cores preserved varved sediment during the Last Glacial Maximum (LGM), indicative for intense, seasonally variable bottom-water production, presumably caused by brine injection in polynias and shelf-ice plowing in front of the ice shelf, which had advanced toward the shelf edge. The following postglacial bioturbated mud favors at least partially open surface water and occasionally intensified iceberg calving. The termination of varvation marked the retreat of the EAIS from the shelf edge around 19 ka BP. The timing coincides with Meltwater Pulse 19 ka from the Northern Hemisphere (NH) and with the initiation of the temperature increase over East Antarctica. After a short ice re-advance, a second retreat occurred around 16 ka - also a time of enhanced global sea-level rise and a period when glaciers rapidly retreated in Patagonia. Sediments from the central Scotia Sea are located in the prolongation of the “iceberg alley”, where icebergs exit the Weddell Sea to the north. Accordingly, this is an excellent location to trace ice-sheet dynamics. Sites MD07-3134 and MD07-3133 document four phases of enhanced iceberg activity as indicated by the amount of small ice-rafted debris (IRD) at 19.5, 16.5,14.5, and 12 ka. The first two are most likely related to the two ice-sheet retreat signals documented by the Weddell Sea sites

  9. Attack or retreat: contrasted defensive tactics used by Cyprian honeybee colonies under attack from hornets.

    PubMed

    Papachristoforou, Alexandros; Rortais, Agnès; Sueur, Jérôme; Arnold, Gérard

    2011-02-01

    This study describes the tactics used by Cyprian honeybees (Apis mellifera cypria) to defend their colonies against hornet (Vespa orientalis orientalis) attacks. We use simulated hornet attacks and a combination of video recordings and image analysis to reveal, for the first time, contrasted intra-subspecies defensive tactics that operate at the colony level during predation. In some colonies, when attacked, the numbers of guards at the hive entrance increases rapidly to attack, engulf, and kill invading hornets. In other colonies, guards avoid conflicts with hornets by retreating gradually and by forming a defensive line of honeybees at the hive entrance. Retreater colonies have propolis walls at the hive entrances with small apertures that are too narrow to allow the hornet to access the hive and that therefore reinforces entrance protection. On the contrary, attacker colonies have propolis walls with large openings through which the hornet can pass; these bees block the hornet's access by intensively guarding the hive entrance. We experimentally destroy propolis walls to test whether colonies consistently rebuild walls with the same intrinsic characteristics and we also monitor the survival rate of each anti-predator tactic after massive natural predation by hornets.

  10. The Comparative Efficacy of Different Files in The Removal of Different Sealers in Simulated Root Canal Retreatment- An In-vitro Study

    PubMed Central

    Kanaparthy, Aruna

    2016-01-01

    Introduction Root canal treatment enjoys a high success rate all over the world and has saved billions of teeth from extraction. However, there are instances of failure, the main causes being insufficient cleaning and inadequate obturation. In such cases the most conservative treatment option would be non-surgical retreatment. It requires regaining access to the entire root canal system through removal of the original root canal filling thus permitting further cleaning and re- obturation. Removal of gutta-percha and sealer becomes a critical step to gain access to the root canal system, remove necrotic tissue debris, bacteria and infected dentin. Aim To compare and evaluate the efficacy of manual hand Hedstrom files and two rotary retreatment file systems ProTaper Universal retreatment files and MtwoR (retreatment) files in the removal of root canal filling material during root canal retreatment and the influence of the type of sealers zinc oxide eugenol and AH plus on the presence of remaining debris in the reinstrumented canals in the apical, middle and coronal third. Materials and Methods Sixty single rooted human premolar teeth were divided into 3 Groups of 20 teeth each Group I (20 Teeth): prepared using hand K Files, Group II (20 Teeth): prepared using ProTaper rotary system and Group III (20 Teeth): prepared using Mtwo rotary system. In Groups- IA, IIA, IIIA: (10 teeth each) Obturation was done using Zinc Oxide Eugenol sealer and gutta percha. In Groups- IB, IIB, IIIB: (10 teeth each) obturation was done with AH Plus sealer and gutta percha. All the teeth were subjected to retreatment. Groups IA and IB with Hedstrom files, Groups IIA and IIB with ProTaper retreatment files and for Groups IIIA and IIIB with Mtwo retreatment Files. The roots were longitudinally split and were observed under a stereomicroscope for remaining amount of filling material on the canal walls. Statistical analysis was done using One–way ANOVA (Analysis of variance) test and Tukey

  11. Knickpoint formation and retreat: stairway to heaven or pathway to declivity

    NASA Astrophysics Data System (ADS)

    Rengers, Francis; Tucker, Gregory

    2016-04-01

    The importance of knickpoints in shaping fluvial systems has been observed in laboratory settings, small experimental plots, and at the landscape scale. By creating a step in a river's longitudinal profile, knickpoints can shield upstream tributaries from a much lower base level, and therefore represent a buffer in the energy transfer of a stream system. Knickpoints are located at a transition point between the potential energy of material stored upstream and the kinetic energy of erosion processes and sediment transport below the knickpoint. We hypothesize that the long-term persistence of a discrete, retreating knickpoint requires a balance between the fluvial erosion of the feature, and sedimentation rates downstream. Here we present the results of a short-term (four year) study of knickpoint morphology in a natural gully system to better constrain the conditions necessary to preserve distinct knickpoints over time. We monitored knickpoint erosion using time-lapse photography, repeat terrestrial lidar, soil moisture monitoring, and rainfall-runoff measurements. Our results indicate that shallow subsurface hydrology leads to knickpoint erosion via mass failure, and produces a stable and predictable morphological signature of knickpoint erosion (amphitheater shaped heads). We generalized these observations into a numerical model of erosion/sedimentation to understand the geomorphic legacy of knickpoints in deeply incised gullies. Modeling showed that knickpoints can maintain an incisional step for hundreds to thousands of years when knickpoints retreat via mass failure and sediment is removed from the knickpoint base by fluvial scour. To test simulations of long-term stability generated by the numerical model, we used Optically Stimulated Luminesence to date alluvial deposits at existing gully knickpoints. This geochronological dating confirmed that gully knickpoints have been active in our study area for hundreds to thousands of years, particularly during drought

  12. Pathological organizations and psychic retreats in eating disorders.

    PubMed

    Kadish, Yael Adira

    2012-04-01

    A set of characteristic symptoms allow for the relatively straightforward diagnosis of eating disorders. Simultaneously and paradoxically, underlying the eating disorders are a wide variety of personality organizations/disorders, stretching from the neurotic to the borderline and narcissistic, and even to conditions approaching psychosis. This paper will argue that the inherent commonalities can be ascribed to pathological organizations of a similar nature and quality, operational across the spectrum of eating disorders and functioning in a particular, sadomasochistic way. The typical forms that eating disorders take are based on the specific ways that food and the body are used, that is, symptom manifestation. These distinctive symptom manifestations appear to be related to Steiner's (1982, 1993) notion of a psychic retreat. Pathological organizations and psychic retreats are latent until called upon either sporadically or continuously. When activated, these defensive structures operate like a complex psychic skeleton around which the unique psychodynamics of each patient become rearranged and thereby transformed.

  13. Scientific Investigators Retreat Brings Like Minds Together | Poster

    Cancer.gov

    Scientists throughout NCI gathered at the 2016 Intramural Scientific Investigators Retreat on Jan. 12, at the Ronald Reagan Building and International Trade Center, to discuss the results of their research with fellow investigators. Several researchers who have made significant advances toward the goal of eliminating the threat of cancer spoke to a packed auditorium of like-minded experts. Speaker topics included the role genetics play in the risk of breast cancer, using fiberglass to...

  14. Retreatment Predictions in Odontology by means of CBR Systems

    PubMed Central

    Campo, Livia; Aliaga, Ignacio J.; García, Alvaro Enrique; Villarubia, Gabriel; Corchado, Juan M.

    2016-01-01

    The field of odontology requires an appropriate adjustment of treatments according to the circumstances of each patient. A follow-up treatment for a patient experiencing problems from a previous procedure such as endodontic therapy, for example, may not necessarily preclude the possibility of extraction. It is therefore necessary to investigate new solutions aimed at analyzing data and, with regard to the given values, determine whether dental retreatment is required. In this work, we present a decision support system which applies the case-based reasoning (CBR) paradigm, specifically designed to predict the practicality of performing or not performing a retreatment. Thus, the system uses previous experiences to provide new predictions, which is completely innovative in the field of odontology. The proposed prediction technique includes an innovative combination of methods that minimizes false negatives to the greatest possible extent. False negatives refer to a prediction favoring a retreatment when in fact it would be ineffective. The combination of methods is performed by applying an optimization problem to reduce incorrect classifications and takes into account different parameters, such as precision, recall, and statistical probabilities. The proposed system was tested in a real environment and the results obtained are promising. PMID:26884749

  15. Retreatment Predictions in Odontology by means of CBR Systems.

    PubMed

    Campo, Livia; Aliaga, Ignacio J; De Paz, Juan F; García, Alvaro Enrique; Bajo, Javier; Villarubia, Gabriel; Corchado, Juan M

    2016-01-01

    The field of odontology requires an appropriate adjustment of treatments according to the circumstances of each patient. A follow-up treatment for a patient experiencing problems from a previous procedure such as endodontic therapy, for example, may not necessarily preclude the possibility of extraction. It is therefore necessary to investigate new solutions aimed at analyzing data and, with regard to the given values, determine whether dental retreatment is required. In this work, we present a decision support system which applies the case-based reasoning (CBR) paradigm, specifically designed to predict the practicality of performing or not performing a retreatment. Thus, the system uses previous experiences to provide new predictions, which is completely innovative in the field of odontology. The proposed prediction technique includes an innovative combination of methods that minimizes false negatives to the greatest possible extent. False negatives refer to a prediction favoring a retreatment when in fact it would be ineffective. The combination of methods is performed by applying an optimization problem to reduce incorrect classifications and takes into account different parameters, such as precision, recall, and statistical probabilities. The proposed system was tested in a real environment and the results obtained are promising.

  16. Retreatment Predictions in Odontology by means of CBR Systems.

    PubMed

    Campo, Livia; Aliaga, Ignacio J; De Paz, Juan F; García, Alvaro Enrique; Bajo, Javier; Villarubia, Gabriel; Corchado, Juan M

    2016-01-01

    The field of odontology requires an appropriate adjustment of treatments according to the circumstances of each patient. A follow-up treatment for a patient experiencing problems from a previous procedure such as endodontic therapy, for example, may not necessarily preclude the possibility of extraction. It is therefore necessary to investigate new solutions aimed at analyzing data and, with regard to the given values, determine whether dental retreatment is required. In this work, we present a decision support system which applies the case-based reasoning (CBR) paradigm, specifically designed to predict the practicality of performing or not performing a retreatment. Thus, the system uses previous experiences to provide new predictions, which is completely innovative in the field of odontology. The proposed prediction technique includes an innovative combination of methods that minimizes false negatives to the greatest possible extent. False negatives refer to a prediction favoring a retreatment when in fact it would be ineffective. The combination of methods is performed by applying an optimization problem to reduce incorrect classifications and takes into account different parameters, such as precision, recall, and statistical probabilities. The proposed system was tested in a real environment and the results obtained are promising. PMID:26884749

  17. Utility of bortezomib retreatment in relapsed or refractory multiple myeloma patients: a multicenter case series.

    PubMed

    Wolf, Jeffrey; Richardson, Paul G; Schuster, Michael; LeBlanc, Annette; Walters, Ian B; Battleman, David S

    2008-10-01

    Bortezomib therapy has become an important part of the standard of care for patients with relapsed multiple myeloma, and preliminary clinical evidence suggests that bortezomib retreatment in patients previously treated with the drug may prolong disease control. This retrospective study was designed to clarify the utility of bortezomib as a repeat therapy. We reviewed records from 3 major cancer centers that had participated in the phase II (SUMMIT or CREST) or phase III (APEX) registration studies to identify patients who were subsequently retreated off protocol with bortezomib-based therapy. We found 22 patients who received bortezomib retreatment following a 60 or more day gap between bortezomib treatments. Twelve patients had intervening therapy between initial bortezomib treatment and bortezomib retreatment. During retreatment, 14 of 22 patients received bortezomib in combination with another antineoplastic agent. The overall response rate for bortezomib retreatment was 50% (9% complete responses). The median length of retreatment was 5.1 months in responding patients and 2.4 months in nonresponding patients. Therapy was terminated due to unmanageable toxicity in 2 patients during retreatment, compared with 6 patients during initial treatment. During retreatment, no patients required dose reduction due to peripheral neuropathy, compared to 4 patients during their initial treatment. Thus, bortezomib retreatment appears to be safe and effective. Favorable observed response rates with bortezomib retreatment suggest that it may be a viable option for relapsed or refractory multiple myeloma, even in patients previously exposed to bortezomib.

  18. On the Lateral Retreat of Salt Marshes: Field Monitoring in the Venice Lagoon (Italy)

    NASA Astrophysics Data System (ADS)

    Solari, L.

    2015-12-01

    Salt marshes are geomorphic structures located in ecotone environments such as lagoon and estuaries, providing lot of ecosystem services to local population. In the last decades they are disappearing due to several factors such as sea level rise, subsidence and edge erosion due to surface waves. The latter is likely the chief mechanism modeling marsh boundaries and leading to the loss of wide marsh areas. In the case of the Venice Lagoon, from the beginning of the last century, the whole salt marsh surface has more than halved and trends indicate that the salt marshes might completely disappear over the next 50 years. Here, we present a field monitoring activity on a retreating salt marsh located in the north part of the Lagoon of Venice (Italy). The marsh is subject to North-East (Bora) wind. Marsh area loss during the last decades has been documented through the comparison of georeferenced aerial photographs showing a retreat rate of the order of 1 m/year. Field measurements started by the end of November 2013 and consist of: salt marsh bank geometry at different cross-sections and wave climate in the lagoon about 30 m in front of the salt marsh. Erosion data are obtained by means of erosion pins located horizontally on the marsh scarp; at higher banks (about 0.9 m), two pins are located along the same vertical direction, for lower banks (about 0.4 m), only one pin is employed. Significant wave height has been measured during three storm surges by means of pressure transducers. The measured wave climate in front of the bank was then put into relationship with the offshore wave climate estimated using wind data (intensity and direction) and bathymetric data. Wind intensity and direction is measured hourly by several measurement stations located in the Lagoon of Venice. In this way, it is possible to extrapolate wave climate hourly at the monitored marsh and calculate the wave power that acted on the bank in a given time interval. Field survey revealed that the

  19. The response of the ionosphere to intense geomagnetic storms in 2012 using GPS-TEC data from East Africa longitudinal sector

    NASA Astrophysics Data System (ADS)

    Tesema, F.; Damtie, B.; Nigussie, M.

    2015-12-01

    The response of the ionosphere to intense magnetic storms has been studied using total electron content (TEC). TEC data recorded by a series of GPS receivers at a longitude ∼ 35 ° E covering a wide range of latitudes (32 ° S to 68 ° N, geographic) is analyzed to study spatio-temporal modifications of the vertical TEC (vTEC) during storms on 07 and 09 March 2012 and on 14 July 2012. We have observed main phase positive response at equatorial ionization anomaly (EIA) crests and mid latitude regions in all the storms. These main phase positive responses are associated with vertical drift enhancement (intensified equatorial electrojet (EEJ)) and the mechanical effect of equatorward neutral wind after an auroral activity. A daytime substantial depletion of TEC at low latitude region was observed on 08 March 2012. This is due to the combined effects of oversheilding and disturbance dynamo electric field that drive large downward drifts during the day. The low latitude and equatorial ionospheric response in the recovery phase days of March storm is found to be largely associated with the disturbance dynamo field that suppressed the upward E × B drift from EEJ observations. The summer negative and winter positive response in July storm as well as mid latitude positive response in March storm was associated with the composition changes as depicted by the O to N2 ratio from GUVI measurements.

  20. Phytoplankton distribution in the Western Arctic Ocean during a summer of exceptional ice retreat

    NASA Astrophysics Data System (ADS)

    Coupel, P.; Jin, H. Y.; Ruiz-Pino, D.; Chen, J. F.; Lee, S. H.; Li, H. L.; Rafizadeh, M.; Garçon, V.; Gascard, J. C.

    2011-07-01

    A drastic ice decline in the Arctic Ocean, triggered by global warming, could generate rapid changes in the upper ocean layers. The ice retreat is particularly intense over the Canadian Basin where large ice free areas were observed since 2007. The CHINARE 2008 expedition was conducted in the Western Arctic (WA) ocean during a year of exceptional ice retreat (August-September 2008). This study investigates whether a significant reorganization of the primary producers in terms of species, biomass and productivity has to be observed in the WA as a result of the intense ice melting. Both pigments (HPLC) and taxonomy (microscopy) acquired in 2008 allowed to determine the phytoplanktonic distribution from Bering Strait (65° N) to extreme high latitudes over the Alpha Ridge (86° N) encompassing the Chukchi shelf, the Chukchi Borderland and the Canadian Basin. Two different types of phytoplankton communities were observed. Over the ice-free Chukchi shelf, relatively high chl-a concentrations (1-5 mg m-3) dominated by 80 % of diatoms. In the Canadian Basin, surface waters are oligotrophic (<0.1 mg m-3) and algal assemblages were dominated by haptophytes and diatoms while higher biomasses (~0.4 mg m-3) related to a deep Subsurface Chlorophyll Maximum (SCM) are associated to small-sized (nano and pico) phytoplankton. The ice melting onset allows to point out three different zones over the open basin: (i) the ice free condition characterized by deep and unproductive phytoplankton communities dominated by nanoplankton, (ii) an extended (78°-83° N) Active Melting Zone (AMZ) where light penetration associated to the stratification start off and enough nutrient availability drives to the highest biomass and primary production due to both diatoms and large flagellates, (iii) heavy ice conditions found north to 83° N allowing light limitation and consequently low biomass and primary production associated to pico and nanoplankton. To explain the poverty (Canadian Basin) and the

  1. Clinical microscopic analysis of ProTaper retreatment system efficacy considering root canal thirds using three endodontic sealers.

    PubMed

    Só, Marcus Vinícius Reis; De Figueiredo, Jose Antônio Poli; Freitas Fachin, Elaine Vianna; Húngaro Duarte, Marco Antônio; Pereira, Jefferson Ricardo; Kuga, Milton Carlos; Da Rosa, Ricardo Abreu

    2012-09-01

    To evaluate the efficacy of ProTaper Universal rotary retreatment system and the influence of sealer type on the presence of filling debris in the reinstrumented canals viewed in an operative clinical microscope. Forty-five palatal root canals of first molars were filled with gutta-percha and one of the following sealers: G1, EndoFill; G2, AH Plus; G3, Sealapex. The canals were then reinstrumented with ProTaper Universal rotary system. Roots were longitudinally sectioned and examined under an operative clinical microscope (10×), and the amount of filling debris on canal walls was analyzed using the AutoCAD 2004 software. A single operator used a specific software tool to outline the canal area and the filling debris area in each third (cervical, middle, and apical), as well as the total canal area. Data were analyzed by Kruskal-Wallis test and Tukey test at P < 0.05. Sealapex demonstrated significant differences in the average of filling debris area/canal among the 3 thirds. This group revealed that apical third showed more debris than the both cervical and middle third (P < 0.0001). Endofill presented significantly more filling debris than Sealapex in the cervical third (P < 0.05). In the middle (P = 0.12) and apical third (P = 0.10), there were no differences amongst groups. Debris was left in all canal thirds, regardless of the retreatment technique. The greatest differences between techniques and sealers were found in the cervical third.

  2. Retreatability of Root Canals Obturated Using Gutta-Percha with Bioceramic, MTA and Resin-Based Sealers

    PubMed Central

    Uzunoglu, Emel; Yilmaz, Zeliha; Sungur, Derya Deniz; Altundasar, Emre

    2015-01-01

    Introduction: The aim of this study was to evaluate the retreatability of root canals obturated with gutta-percha (GP) and three different endodontic sealers [iRoot SP (bioceramic sealer), MTA Fillapex (MTA-based sealer) and AH-26 (epoxy resin-based sealer)] using the ProTaper Universal Retreatment (PTR) system. Methods and Materials: Forty extracted single-rooted human teeth were prepared with universal ProTaper files up to F4 (40/0.06). Specimens were randomly divided into four groups according to obturation technique/material: single-cone GP/AH-26, lateral compaction of GP/AH-26, single-cone GP/iRoot SP, and single-cone GP/MTA Fillapex. Root fillings were removed with PTR. The time taken to reach the working-length (TWL) was recorded. Roots were longitudinally sectioned and each half was evaluated using a stereomicroscope. Three observers scored each third of all specimen. Obtained data were analyzed using the Kruskal-Wallis, Mann-Whitney U, Welch and Games-Howell tests. The level of significance was set at 0.05. Results: In single-cone GP/MTA Fillapex group the TWL was significantly shorter. The remnant of filling material in the apical and middle thirds of groups was similar and higher than the coronal thirds. Conclusion: None of the tested sealers were completely removed from the root canal system. PMID:25834591

  3. Insights into lateral marsh retreat mechanism through localized field measurements

    NASA Astrophysics Data System (ADS)

    Bendoni, M.; Mel, R.; Solari, L.; Lanzoni, S.; Francalanci, S.; Oumeraci, H.

    2016-02-01

    Deterioration of salt marshes may be due to several factors related to increased anthropic pressure, sea level rise, and erosive processes. While salt marshes can reach equilibrium in the vertical direction, adapting to sea level rise, they are inherently unstable in the horizontal direction. Marsh boundaries are characterized by scarps with bare sediment below the vegetated surface layer that can be easily removed by wave-induced erosion. In this work, we explore the different mechanisms involved in the erosion of marsh borders through the interpretation of field data. The analysis is based on a systematic field monitoring of a salt marsh in the Venice Lagoon subject to lateral erosion. Measurements included horizontal retreat of the scarp at various locations and wave height in front of the marsh during three storm surges. Continuous erosion and mass failures alternated during the observed period, leading to an average retreat up to 80 cm/yr. The data, collected roughly every month for 1.5 year, indicate that the linear relation that links the observed erosion rate to the impinging wave power exhibits a larger slope than that already estimated in literature on the basis of long-term surveys. Moreover, an increase in the gradient of erodibility is detected along the marsh scarp, due to the combined action of soil strengthening by vegetation on the marsh surface and the impact of wave breaking at the bank toe, which promote cantilever failures and increase the lateral erosion rate.

  4. A Palaeohydrological Shift during Neogene East Antarctic Ice Sheet Retreat

    NASA Astrophysics Data System (ADS)

    Rees-Owen, R. L.; Newton, R.; Ivanovic, R. F.; Francis, J.; Tindall, J. C.; Riding, J. B.

    2015-12-01

    The East Antarctic Ice Sheet is an important driver of global climate, playing a particular role in governing albedo and atmospheric circulation (eg. Singh et al., 2013). Recent evidence from marine sediment and terrestrial glaciovolcanic sequences suggests that the EAIS underwent periodic retreat and collapse in response to warmer climates during the late Neogene (14 to 3 million years ago). Mummified prostrate trees recovered from palaeosols at Oliver Bluffs in the Beardmore Glacier region, Transantarctic Mountains (85° S), represent a rare insight into the terrestrial palaeoclimate during one of these periods of retreat. Prostrate trees are an understudied but useful tool for interrogating endmember (e.g. periglacial) environments at high altitudes and latitudes. We present exciting new palaeoclimate data from the sequence at Oliver Bluffs. δ18O analysis of tree ring cellulose suggests that Antarctic summer palaeoprecipitation was enriched relative to today (-25 to -5‰ for ancient, -35 to -20‰ for modern); consistent with our isotope-enabled general circulation model simulations. The MBT/CBT palaeothermometer gives a summer temperature of 3-6ºC, consistent with other palaeobotanical climate indices. These geological and model data have wide-ranging implications for our understanding of the hydrological cycle during this time period. We present data suggesting that changes in moisture recycling and source region indicate a markedly different hydrological cycle.

  5. Evaluation of three different rotary systems during endodontic retreatment - Analysis by scanning electron microscopy

    PubMed Central

    Vidal, Flávia-Teixeira; Nunes, Eduardo; Horta, Martinho-Campolina-Rebello; Freitas, Maria-Rita-Lopes-da Silva

    2016-01-01

    Background Endodontic therapy is considered a series of important and interdependent steps, and failure of any of these steps may compromise the treatment outcome. This study aimed to evaluate the effectiveness of three different rotary systems in removing obturation materials during endodontic retreatment using scanning electron microscopy (SEM) analysis. Material and Methods Thirty-six endodontically treated teeth were selected and divided into 3 groups of 10 and 1 control group with 6 dental elements. The groups were divided according to the rotary system used for removing gutta-percha, as follows: G1: ProTaper system; G2: K3 system; G3: Mtwo system; and G4: Control group. Thereafter, the roots were split and the sections were observed under SEM, for analysis and counting of clear dentinal tubules, creating the variable “degree of dentinal tubule patency” (0: intensely clear; 1: moderately clear; 2: slightly clear; 3: completely blocked). The data were subjected to the Friedman and Kruskal-Wallis statistical tests. Results No differences were observed in the “degree of dentinal tubule patency” neither between the root thirds (to each evaluated group) nor between the groups (to each evaluated third). Nevertheless, when the three root thirds were grouped (providing evaluation of all root extension), the “degree of dentinal tubule patency” was lower in G1 than in G3 (p<0.05), but showed no differences neither between G1 and G2 nor G2 and G3. Conclusions No technique was able to completely remove the canal obturation material, despite G1 having shown better results, although without significant difference to G2 Key words:Scanning electron microscopy, NiTi, retreatment. PMID:27034750

  6. West Antarctic Ice Sheet retreat from Pine Island Bay during the Holocene: New insights into forcing mechanisms

    NASA Astrophysics Data System (ADS)

    Hillenbrand, Claus-Dieter; Smith, James; Kuhn, Gerhard; Poole, Chris; Hodell, David; Elderfield, Harry; Kender, Sev; Williams, Mark; Peck, Victoria; Larter, Robert; Klages, Johann; Graham, Alastair; Forwick, Matthias; Gohl, Karsten

    2013-04-01

    The Amundsen Sea sector of the largely marine-based and therefore conditionally unstable West Antarctic Ice Sheet (WAIS) contains enough ice to raise global sea level by ca. 1.5 metres. At present, ice streams draining this sector into the Southern Ocean, especially glaciers flowing into Pine Island Bay in the eastern Amundsen Sea embayment, are undergoing considerable mass loss characterised by major thinning, flow acceleration and rapid grounding-line retreat. Sub-ice shelf melting by relatively warm Circumpolar Deep Water (CDW) upwelling onto the continental shelf is held responsible for these dynamical changes but atmospheric warming in West Antarctica may also have contributed to them. In contrast to the modern situation, the long-term history of the Amundsen Sea sector and the mechanisms forcing its deglaciation during the Holocene are only poorly constrained. We will present new palaeoenvironmenal data obtained from marine sediment cores collected in Pine Island Bay. The cores targeted shallow sites on the inner continental shelf and successfully recovered sedimentary sequences bearing calcareous microfossils. Radiocarbon ages on these microfossils demonstrate that the grounding line of the WAIS retreated to within ~100 km of its modern position before ca. 10 kyr BP (thousand years before present), which is consistent with an early WAIS retreat from near-coastal locations in the western Amundsen Sea embayment. Currently, there is no evidence that the grounding line had retreated landward of its modern position during the Holocene. Therefore, the chronological constraints may imply that during the last 10 kyr any episodes of fast grounding-line retreat similar to those observed today were short-lived and rare. Preliminary geochemical data from benthic and planktonic foraminifera tests in the cores from Pine Island Bay reveals that intense CDW upwelling coincided with and may have forced the deglaciation of the inner continental shelf. Furthermore, we observe

  7. Ecological Succession, Land use Changes and Soil Organic C Stock in a Lake Retreat Area (Main Ethiopian Rift Valley)

    NASA Astrophysics Data System (ADS)

    Nyssen, J.; Temesgen, H.; Lemenih, M.; Zenebe, A.; Kindu, M.; Haile, M.

    2007-12-01

    In the Main Ethiopian Rift Valley, ecological succession is related to continuous lake retreat (Nyssen et al., 2004). Human activities, through their impact on land use and cover, affect this ecological succession. Through a remote sensing study, we extricated ecological succession and human activity as causative factors for land use and cover changes (LUCC) and explored which impact this has on soil organic C (SOC) stock in lake retreat areas. Remote sensing data used include a Landsat MSS from 1973, a Landsat TM from 1986 and a Landsat ETM+ from 2000. A conventional type of classification was used whereby supervised classification of the 2000 image was supplemented by unsupervised classification of the older datasets. Due to decreased rainfall and water abstraction for intense irrigated agriculture and floriculture in its catchment, Lake Abijata lost 46 % of its area between 2000 and 2006. On the emerged lands, a good ecological succession was observed between 1973 and 1986, with clear evidence for: emerged land -> grassland -> Acacia bushes -> open woodland. Between 1986 and 2000, LUCC tendencies were totally reversed and woody vegetation decreased strongly, indicating increased human impact (Habtamu et al., 2007). Based on an analysis of the Landsat imagery, coupled with soil and land use studies, determinants for SOC stock were found. Firstly, SOC stock significantly differs between cultivated land and grazing land (3301 and 2626 g m-2) on the one hand, and woodland (4594 g m-2) on the other. The strongest explanation of SOC stock is related to the duration of emergence and hence of pedogenesis. Its proxy, elevation, explains much of the variability of SOC (R2 = 0.48). Using a multiple regression model involving elevation and IR reflectance, the SOC stock in the study area could be assessed at 2196 (+ - 1517) g m-2 SOC in 2000, against 3222 (+ - 1639) g m-2 in 1973 (Nyssen et al., 2007), which is related to the post-1986 reversing of ecological succession in

  8. Tuberculosis treatment outcomes among retreatment patients registered by private practitioners in Myanmar.

    PubMed

    Win, A N; Edginton, M E; Hinderaker, S G; Minn, N N; Linn, A K

    2012-09-21

    The objectives of this retrospective cohort study were to report treatment outcomes and identify factors associated with treatment failure among all retreatment tuberculosis (TB) patients registered in the public-private mix DOTS programme of Populations Services International-Myanmar over 6 years. Among 3643 retreatment patients, 2657 (73%) were successfully treated and 309 (8.5%) failed. This study shows that retreatment patients who have failed treatment for their first TB episode are almost twice as likely to fail a second time (13.5%). We have identified some key programmatic challenges associated with retreatment TB in the private sector, and steps are being taken to address this issue.

  9. Probabilistic estimation of dun retreate on the Gold Coast, Australia

    USGS Publications Warehouse

    Palmsten, Margaret L.; Splinter, Kristen D.; Plant, Nathaniel G.; Stockdon, Hilary F.

    2014-01-01

    Sand dunes are an important natural buffer between storm impacts and development backing the beach on the Gold Coast of Queensland, Australia. The ability to forecast dune erosion at a prediction horizon of days to a week would allow efficient and timely response to dune erosion in this highly populated area. Towards this goal, we modified an existing probabilistic dune erosion model for use on the Gold Coast. The original model was trained using observations of dune response from Hurricane Ivan on Santa Rosa Island, Florida, USA (Plant and Stockdon 2012. Probabilistic prediction of barrier-island response to hurricanes, Journal of Geophysical Research, 117(F3), F03015). The model relates dune position change to pre-storm dune elevations, dune widths, and beach widths, along with storm surge and run-up using a Bayesian network. The Bayesian approach captures the uncertainty of inputs and predictions through the conditional probabilities between variables. Three versions of the barrier island response Bayesian network were tested for use on the Gold Coast. One network has the same structure as the original and was trained with the Santa Rosa Island data. The second network has a modified design and was trained using only pre- and post-storm data from 1988-2009 for the Gold Coast. The third version of the network has the same design as the second version of the network and was trained with the combined data from the Gold Coast and Santa Rosa Island. The two networks modified for use on the Gold Coast hindcast dune retreat with equal accuracy. Both networks explained 60% of the observed dune retreat variance, which is comparable to the skill observed by Plant and Stockdon (2012) in the initial Bayesian network application at Santa Rosa Island. The new networks improved predictions relative to application of the original network on the Gold Coast. Dune width was the most important morphologic variable in hindcasting dune retreat, while hydrodynamic variables, surge and

  10. Probabilistic estimation of dune retreat on the Gold Coast, Australia

    USGS Publications Warehouse

    Palmsten, Margaret L.; Splinter, Kristen D.; Plant, Nathaniel G.; Stockdon, Hilary F.

    2014-01-01

    Sand dunes are an important natural buffer between storm impacts and development backing the beach on the Gold Coast of Queensland, Australia. The ability to forecast dune erosion at a prediction horizon of days to a week would allow efficient and timely response to dune erosion in this highly populated area. Towards this goal, we modified an existing probabilistic dune erosion model for use on the Gold Coast. The original model was trained using observations of dune response from Hurricane Ivan on Santa Rosa Island, Florida, USA (Plant and Stockdon 2012. Probabilistic prediction of barrier-island response to hurricanes, Journal of Geophysical Research, 117(F3), F03015). The model relates dune position change to pre-storm dune elevations, dune widths, and beach widths, along with storm surge and run-up using a Bayesian network. The Bayesian approach captures the uncertainty of inputs and predictions through the conditional probabilities between variables. Three versions of the barrier island response Bayesian network were tested for use on the Gold Coast. One network has the same structure as the original and was trained with the Santa Rosa Island data. The second network has a modified design and was trained using only pre- and post-storm data from 1988-2009 for the Gold Coast. The third version of the network has the same design as the second version of the network and was trained with the combined data from the Gold Coast and Santa Rosa Island. The two networks modified for use on the Gold Coast hindcast dune retreat with equal accuracy. Both networks explained 60% of the observed dune retreat variance, which is comparable to the skill observed by Plant and Stockdon (2012) in the initial Bayesian network application at Santa Rosa Island. The new networks improved predictions relative to application of the original network on the Gold Coast. Dune width was the most important morphologic variable in hindcasting dune retreat, while hydrodynamic variables, surge and

  11. Writing Retreat Increases Productivity And Community For Women Geoscientists

    NASA Astrophysics Data System (ADS)

    O'Connell, S.; Holmes, M.

    2011-12-01

    Five, weeklong geoscientist writing retreats have been completed with an NSF ADANCE PAID grant. During the five nights and four and a half days, eight to twenty-four academics have gathered in a rural setting outside of Boston to get to focus on writing papers and proposals while getting to know each other. Participants range in age and experience from graduate students to emeritus professors. Over twenty papers and proposals acknowledge their production, in part to this writing retreat. Impact extends beyond papers as informal mentoring and discussions at meals and in the evenings centers on succeeding in academia. Research and teaching are foremost in the conversation. Post-docs learn strategies for applying for jobs and grants, and senior professors discuss strategies for working with academic administrations, running departments and mentoring students. They also learn new technologies and perspectives from younger participants. Particularly helpful are discussions on work-life balance. Networking opportunities extend beyond the retreat as participants join each other at their home institutions to give seminars, develop research projects and mentor each other's students. All weeks follow the same format. Participants arrive Sunday and meet during an evening welcome reception. Monday is devoted to writing. Tuesday a writing coach is available. In the morning, using examples from the scientific literature, she discusses strategies and techniques for writing clearly at a group session. During the afternoon, participants work with the coach individually or in small groups to improve their own writing projects. Wednesday evening a skill session is offered on a topic of interest. These have included undergraduate research, NSF funding, productive techniques for dealing with conflict, and generational characteristics and attitudes, which can hamper communication. A Thursday evening wrap-up session prepares participants for Friday's departure. We believe that this model

  12. The Writing Retreat: A High-Yield Clinical Faculty Development Opportunity in Academic Writing

    PubMed Central

    Cable, Christian T.; Boyer, Debra; Colbert, Colleen Y.; Boyer, Edward W.

    2013-01-01

    Background The need for consistent academic productivity challenges junior clinician-scholars, who often lack the aptitude to ensure efficient production of manuscripts. Intervention To solve this problem, an academic division of a major medical center developed an off-site writing retreat. The purpose of the retreat was not to teach writing skills, but to offer senior mentor assistance with a focus on the elements of manuscript writing. Methods The retreat paired senior faculty members with junior staff. Senior faculty identified manuscript topics and provided real-time writing and editing supervision. Team-building exercises, midcourse corrections, and debriefing interviews were built into the retreat. The number of manuscripts and grant proposals generated during the 2008–2011 retreats was recorded, and the program was evaluated by using unstructured debriefing interviews. Results An average of 6 to 7 faculty members and fellows participated in each retreat. During the past 4 years, participants produced an average of 3 grant proposals and 7 manuscripts per retreat. After the writing retreat, each fellow and junior faculty member produced an average of 4 scholarly products per year, compared to fewer than 2 for prior years' retreats. Participant feedback indicated the success of the retreat resulted from protected time, direct mentorship by the scholars involved, and pairing of authors, which allows for rapid production of manuscripts and accelerated the editing process. More than 80% of mentors returned each year to participate. Conclusions The writing retreat is a feasible, effective strategy to increase scholarship among faculty, acceptable to mentees and mentors, and sustainable over time. PMID:24404277

  13. Evaluation of surface alterations in different retreatment nickel-titanium files: AFM and SEM study.

    PubMed

    Can Sağlam, Baran; Görgül, Güliz

    2015-05-01

    The aim of this study was to evaluate the surface changes of nickel titanium (Ni-Ti) rotary retreatment files after three and five uses. Furthermore, the effects of 2% sodium hypochlorite and chloroform solutions and sterilization procedures on the NiTi rotary retreatment surfaces were investigated. ProTaper Retreatment files, R-endo files, and Mtwo retreatment files were used for this study. The palatinal roots of maxillary molar teeth were obturated with gutta percha and Ah26. Retreatment procedures were performed with these retreatment file systems. The surface changes of untreated NiTi rotary files that were used three and five times, immersed in NaOCl and chloroform and subjected to sterilization procedures were investigated with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The RMS values, three dimensional images and SEM images at various magnifications were obtained. RMS values showed that all three NiTi rotary retreatment file systems showed significant deteriorations after three and five uses. Cracks, damages and spiral construction deteriorations were detected in the SEM images after three and five uses. Furthermore, the Mtwo 15 file was broken off after five uses. AFM data indicated that 2% NaOCl caused significant surface deteriorations on NiTi rotary files and both AFM and SEM evaluation showed that chloroform solution and sterilization procedures did not cause significant surface deteriorations. In conclusion, ProTaper retreatment, R-endo, and Mtwo retreatment files showed surface damages depending on retreatment procedures. Clinicians have to consider that retreatment files always have a tendency to break off after the third time they have been used.

  14. Windblown Pliocene diatoms and East Antarctic Ice Sheet retreat.

    PubMed

    Scherer, Reed P; DeConto, Robert M; Pollard, David; Alley, Richard B

    2016-09-20

    Marine diatoms in tillites along the Transantarctic Mountains (TAMs) have been used to suggest a diminished East Antarctic Ice Sheet (EAIS) during Pliocene warm periods. Updated ice-sheet modelling shows significant Pliocene EAIS retreat, creating marine embayments into the Wilkes and Aurora basins that were conducive to high diatom productivity and rapid accumulation of diatomaceous sediments. Here we show that subsequent isostatic uplift exposed accumulated unconsolidated marine deposits to wind erosion. We report new atmospheric modelling utilizing Pliocene climate and derived Antarctic landscapes indicating that prevailing mid-altitude winds transported diatoms towards the TAMs, dominantly from extensive emerged coastal deposits of the Aurora Basin. This result unifies leading ideas from competing sides of a contentious debate about the origin of the diatoms in the TAMs and their link to EAIS history, supporting the view that parts of the EAIS are vulnerable to relatively modest warming, with possible implications for future sea-level rise.

  15. Windblown Pliocene diatoms and East Antarctic Ice Sheet retreat

    NASA Astrophysics Data System (ADS)

    Scherer, Reed P.; Deconto, Robert M.; Pollard, David; Alley, Richard B.

    2016-09-01

    Marine diatoms in tillites along the Transantarctic Mountains (TAMs) have been used to suggest a diminished East Antarctic Ice Sheet (EAIS) during Pliocene warm periods. Updated ice-sheet modelling shows significant Pliocene EAIS retreat, creating marine embayments into the Wilkes and Aurora basins that were conducive to high diatom productivity and rapid accumulation of diatomaceous sediments. Here we show that subsequent isostatic uplift exposed accumulated unconsolidated marine deposits to wind erosion. We report new atmospheric modelling utilizing Pliocene climate and derived Antarctic landscapes indicating that prevailing mid-altitude winds transported diatoms towards the TAMs, dominantly from extensive emerged coastal deposits of the Aurora Basin. This result unifies leading ideas from competing sides of a contentious debate about the origin of the diatoms in the TAMs and their link to EAIS history, supporting the view that parts of the EAIS are vulnerable to relatively modest warming, with possible implications for future sea-level rise.

  16. GPCR Retreat 2014: a good view leads to many discoveries!

    PubMed

    Chidiac, Peter; Hébert, Terence E

    2015-06-01

    The GPCR gods smiled on us last year as the 15th Annual GPCR Retreat was held last October 2nd-4th in Bromont, Québec. The fall colors were at their peak and the meeting attendees were also in fine form. The program was one of the best we have seen at any GPCR-related meeting in years and there was a great deal of excitement about new methodological approaches to understanding receptor biology, new concepts in GPCR signaling and a continued emphasis on translation of these discoveries. This year was also the first year we opened the meeting with a short course on biased agonism and how to measure and analyze it.

  17. Windblown Pliocene diatoms and East Antarctic Ice Sheet retreat.

    PubMed

    Scherer, Reed P; DeConto, Robert M; Pollard, David; Alley, Richard B

    2016-01-01

    Marine diatoms in tillites along the Transantarctic Mountains (TAMs) have been used to suggest a diminished East Antarctic Ice Sheet (EAIS) during Pliocene warm periods. Updated ice-sheet modelling shows significant Pliocene EAIS retreat, creating marine embayments into the Wilkes and Aurora basins that were conducive to high diatom productivity and rapid accumulation of diatomaceous sediments. Here we show that subsequent isostatic uplift exposed accumulated unconsolidated marine deposits to wind erosion. We report new atmospheric modelling utilizing Pliocene climate and derived Antarctic landscapes indicating that prevailing mid-altitude winds transported diatoms towards the TAMs, dominantly from extensive emerged coastal deposits of the Aurora Basin. This result unifies leading ideas from competing sides of a contentious debate about the origin of the diatoms in the TAMs and their link to EAIS history, supporting the view that parts of the EAIS are vulnerable to relatively modest warming, with possible implications for future sea-level rise. PMID:27649516

  18. Windblown Pliocene diatoms and East Antarctic Ice Sheet retreat

    PubMed Central

    Scherer, Reed P.; DeConto, Robert M.; Pollard, David; Alley, Richard B.

    2016-01-01

    Marine diatoms in tillites along the Transantarctic Mountains (TAMs) have been used to suggest a diminished East Antarctic Ice Sheet (EAIS) during Pliocene warm periods. Updated ice-sheet modelling shows significant Pliocene EAIS retreat, creating marine embayments into the Wilkes and Aurora basins that were conducive to high diatom productivity and rapid accumulation of diatomaceous sediments. Here we show that subsequent isostatic uplift exposed accumulated unconsolidated marine deposits to wind erosion. We report new atmospheric modelling utilizing Pliocene climate and derived Antarctic landscapes indicating that prevailing mid-altitude winds transported diatoms towards the TAMs, dominantly from extensive emerged coastal deposits of the Aurora Basin. This result unifies leading ideas from competing sides of a contentious debate about the origin of the diatoms in the TAMs and their link to EAIS history, supporting the view that parts of the EAIS are vulnerable to relatively modest warming, with possible implications for future sea-level rise. PMID:27649516

  19. A Numerical Model of Retreating Alluvial Fan Coasts

    NASA Astrophysics Data System (ADS)

    Hicks, M.; Dickson, M.; Coco, G.

    2006-12-01

    A numerical model has been developed that simulates the wave-driven retreat of partially-consolidated alluvial- fan shores over millennium time-scales. It has been developed to reproduce the shore profiles and coastal erosion rates observed along the Pleistocene glacial-outwash fan built by the Waitaki River on the east coast of New Zealand's South Island. This cliffed shore is currently fronted by a narrow sand-and-gravel beach. The nearshore seabed is formed in Pleistocene substrate and has only a thin and patchy cover of sand. The motivation is to examine the sensitivity of the erosion rates to wave-climate change, sea-level rise, and river sediment supplies. The model is forced by two wave conditions that, when randomly sampled, represent the storm-wave and normal-swell climates of the prototype coast. These each operate for a fixed proportion of the model's yearly time-step. Morphological change is driven by a series of coupled process models. These include scour of the nearshore seabed by shoaling waves, cross-shore exchanges of sand and gravel between the nearshore and beach, berm construction during normal wave conditions, berm overtopping by storm waves with consequent beach stripping and scour of the exposed sub-aerial substrate and cliff-toe notch-cutting, gravity-failure of the cliffs and talus construction between storm events, and beach sediment abrasion. The scour, notching, and transport models are generally based on energetics principles and are calibrated with linear scaling coefficients to match field observations from the prototype coast. Negative feedback regulates the rate of cliff erosion through the protection that is afforded by cliff and substrate material added to the beach. The starting model condition is a sloping alluvial fan inundated by the sea-level rise that followed the last glacial epoch, and the model is run for 6000 years to the present assuming a stable sea level. Initially, the gentle slope of the alluvial fan results in

  20. Cleaning and retreatment protocol for a debonded ceramic restoration

    PubMed Central

    Alonso-Pérez-Barquero, Jorge; Bruguera-Álvarez, August; Agustín-Panadero, Rubén; Fons-Font, Antonio

    2015-01-01

    Objectives: The aim of this article is to propose a resin cement cleaning protocol for use before recementing a debonded restoration. Study Design: Ceramic samples were fabricated from IPS d.sign® and IPS e.max Press® and were treated with hydrofluoric acid etching (HF), or HF+silane (S), or HF+S+adhesive or HF+S+A+resin cement. All samples were placed in a furnace at 650º for one minute in order to attempt to pyrolyze the composite. Each step was examined under scanning electron microscopy (SEM). Results: When the cleaning protocol had been performed, it left a clean and retentive surface. Conclusions: If the restoration is placed in a furnace at 650º for one minute, the composite cement will burn or pyrolyze and disappear, allowing conventional retreatment of the ceramic before rebonding. Key words:Ceramic, debond, surface treatment. PMID:25810843

  1. Holocene Glacial Retreat at Walgreen Coast, West Antarctica

    NASA Astrophysics Data System (ADS)

    Lindow, J.; Johnson, J.; Castex, M.; Wittmann, H.; Smith, J.; Lisker, F.; Gohl, K.; Spiegel, C.

    2012-12-01

    The Walgreen Coast of West Antarctica represents one of the most rapidly changing sectors of the West Antarctic Ice Sheet (WAIS). With the fastest ice streams in the whole Antarctic, the WAIS is characterised by rapid thinning and grounding line retreat. Airborne and satellite-based short-term observations show a doubling of the negative net mass balance between 1996-2006 (Rignot et al., 2008). Furthermore, because the WAIS is largely grounded below sea level, continued inland thinning and grounding line retreat could result in rapid ice sheet collapse, which would raise global sea level by between 3-5 m. However, due to remoteness and challenging accessibility, onshore data is limited to a few isolated nunataks making it difficult to assess the long-term evolution of the glacial dynamics along Walgreen Coast. To address this we present new data from two key areas of the Walgreen Coast; the Kohler Range and the Pine Island Bay. Our 10Be surface exposure ages from erratic boulders in the Kohler Range are the first and reveal that this area became ice-free between 8.3 and 12.3 ka. This implies a long-term thinning rate of 3.3 cm/yr and agrees with similar data published from glaciers eastward. Our ages are also consistent with recent deglaciation models which suggest strong thinning after 15 ka and off-shore sediments shows a concurrent lateral ice-shelf front retreat. Our results suggest an ice-cover at least 300 m thicker in the Kohler Range during the early Holocene and that subsequent average thinning occurred on rates one order of magnitude slower than recent satellite measurements show. This implies that the recent trend in ice-sheet thinning results from a recent dynamic changes rather than a response to long-term thinning. To further constrain the lateral deglaciation history along the eastern Walgreen Coast, namely the Pine Island Glacier, we collected additional samples from a chain of islands, located flow-parallel and downstream of the ice-shelf front. We

  2. WHO in retreat: is it losing its influence?

    PubMed Central

    Godlee, F.

    1994-01-01

    WHO says it has three main functions: to set normative standards; to provide technical advice and assistance on medical matters; and to advocate changes in health policy. During its 46 year history the first two functions have been a constant and uncontroversial backbone through which WHO has earned its reputation for scientific excellence. The third function, advocacy, came to the fore with the launch of Health for All in 1977, after which WHO took a key role in influencing international health policy. WHO's friends and critics alike now say that the organisation is losing its influence and retreating into its technical and biomedical shell. This article maps the changes in WHO's approach over the past 46 years and considers whether fears about its loss of influence are justified. Images p1492-a p1492-b p1493-a p1494-a FIG 1 PMID:7804058

  3. North Atlantic warming and the retreat of Greenland's outlet glaciers.

    PubMed

    Straneo, Fiammetta; Heimbach, Patrick

    2013-12-01

    Mass loss from the Greenland ice sheet quadrupled over the past two decades, contributing a quarter of the observed global sea-level rise. Increased submarine melting is thought to have triggered the retreat of Greenland's outlet glaciers, which is partly responsible for the ice loss. However, the chain of events and physical processes remain elusive. Recent evidence suggests that an anomalous inflow of subtropical waters driven by atmospheric changes, multidecadal natural ocean variability and a long-term increase in the North Atlantic's upper ocean heat content since the 1950s all contributed to a warming of the subpolar North Atlantic. This led, in conjunction with increased runoff, to enhanced submarine glacier melting. Future climate projections raise the potential for continued increases in warming and ice-mass loss, with implications for sea level and climate.

  4. The 21st Annual Prostate Cancer Foundation Scientific Retreat report.

    PubMed

    Miyahira, Andrea K; Simons, Jonathan W; Soule, Howard R

    2015-08-01

    The 21st Annual Prostate Cancer Foundation (PCF) Scientific Retreat was held from October 23-25, 2014, in Carlsbad, CA. This event is the world's foremost scientific meeting focusing on prostate cancer and brings together leading basic, translational and clinical researchers in prostate cancer and other diverse disciplines to discuss the newest findings most likely to advance the understanding of prostate cancer and the clinical care of prostate cancer patients. This year's meeting highlighted themes including: (i) research integrity and standards for scientific reproducibility; (ii) prostate cancer disparities; (iii) mechanisms and models of prostate cancer progression and dormancy; (iv) mechanisms of therapeutic resistance; and (v) advancements in precision medicine treatments, treatment models, and predictive and prognostic biomarkers.

  5. Effects of Teriparatide Retreatment in Osteoporotic Men and Women

    PubMed Central

    Finkelstein, Joel S.; Wyland, Jason J.; Leder, Benjamin Z.; Burnett-Bowie, Sherri-Ann M.; Lee, Hang; Jüppner, Harald; Neer, Robert M.

    2009-01-01

    Context: The stimulatory effect of teriparatide on bone mineral density (BMD) and bone turnover is initially exuberant, but then diminishes. Objective: Our objective was to determine whether retreating with teriparatide after a drug-free period can restore the initial exuberant response to teriparatide. Design and Setting: This was a planned extension of a randomized controlled trial conducted in a single university hospital. Patients and Intervention: Subjects previously participated in a 30-month randomized trial comparing the effects of alendronate (group 1), teriparatide (group 2), or both (group 3) on BMD and bone turnover in men and women with low BMD (phase 1). Subjects who completed phase 1 on their assigned therapy entered phase 2 (months 30–42), during which teriparatide was stopped in groups 2 and 3. Teriparatide was administered to all subjects during months 42 to 54 (phase 3). Main Outcome Measures: We compared changes in BMD and markers of bone turnover (serum osteocalcin, N-terminal propeptide of type 1 collagen, and N-telopeptide) between phase 1 and 3 in subjects receiving teriparatide alone. Results: Posterior-anterior and lateral spine BMD increased 12.5 ± 1.5 and 16.9 ± 1.7%, respectively, during the first 12 months of teriparatide administration and 5.2 ± 0.8 and 6.2 ± 1.8%, respectively, during teriparatide retreatment (P < 0.001 and P = 0.001). Increases in osteocalcin (P < 0.001), N-terminal propeptide of type 1 collagen (P < 0.001), and N-telopeptide (P < 0.001) were greater during the first period of teriparatide administration. Conclusion: The response to teriparatide is attenuated when readministered after a 12-month hiatus. PMID:19401368

  6. Evaluation of a gully headcut retreat model using multitemporal aerial photographs and digital elevation models

    NASA Astrophysics Data System (ADS)

    Campo-Bescós, M. A.; Flores-Cervantes, J. H.; Bras, R. L.; Casalí, J.; Giráldez, J. V.

    2013-12-01

    large fraction of soil erosion in temperate climate systems proceeds from gully headcut growth processes. Nevertheless, headcut retreat is not well understood. Few erosion models include gully headcut growth processes, and none of the existing headcut retreat models have been tested against long-term retreat rate estimates. In this work the headcut retreat resulting from plunge pool erosion in the Channel Hillslope Integrated Landscape Development (CHILD) model is calibrated and compared to long-term evolution measurements of six gullies at the Bardenas Reales, northeast Spain. The headcut retreat module of CHILD was calibrated by adjusting the shape factor parameter to fit the observed retreat and volumetric soil loss of one gully during a 36 year period, using reported and collected field data to parameterize the rest of the model. To test the calibrated model, estimates by CHILD were compared to observations of headcut retreat from five other neighboring gullies. The differences in volumetric soil loss rates between the simulations and observations were less than 0.05 m3 yr-1, on average, with standard deviations smaller than 0.35 m3 yr-1. These results are the first evaluation of the headcut retreat module implemented in CHILD with a field data set. These results also show the usefulness of the model as a tool for simulating long-term volumetric gully evolution due to plunge pool erosion.

  7. Teacher Retreating: The Little Known Behavior That Impacts Teaching and Learning

    ERIC Educational Resources Information Center

    Ratcliff, Nancy J.; Carroll, Kimberly L.; Hunt, Gilbert H.

    2014-01-01

    This paper discusses findings from four years of observational research examining classroom climate. Specifically, findings that focused on one powerful teacher behavior (teacher retreating) were examined. These data indicated that teacher retreating was negatively correlated to the amount of instructional interaction occurring between students…

  8. Ipilimumab retreatment in patients with pretreated advanced melanoma: the expanded access programme in Italy

    PubMed Central

    Chiarion-Sileni, V; Pigozzo, J; Ascierto, P A; Simeone, E; Maio, M; Calabrò, L; Marchetti, P; De Galitiis, F; Testori, A; Ferrucci, P F; Queirolo, P; Spagnolo, F; Quaglino, P; Carnevale Schianca, F; Mandalà, M; Di Guardo, L; Del Vecchio, M

    2014-01-01

    Background: Retreatment with ipilimumab has been shown to re-establish disease control in some patients with disease progression. Here, we report the efficacy and safety of retreatment with ipilimumab 3 mg kg−1 among patients participating in an expanded access programme in Italy. Methods: Patients who achieved disease control during induction therapy were retreated with ipilimumab upon progression (3 mg kg−1 every 3 weeks for up to four doses), providing they had not experienced toxicity that precluded further dosing. Tumour assessments were conducted after retreatment, and patients were monitored throughout for adverse events. Results: Of 855 patients treated with ipilimumab, 51 were retreated upon disease progression. Of these, 28 (55%) regained disease control upon retreatment and 42% were alive 2 years after the first induction dose of ipilimumab; median overall survival was 21 months. Eleven patients (22%) had a treatment-related adverse event of any grade during retreatment. These were generally mild-to-moderate and resolved within a median of 4 days. No new types of toxicity were reported. Conclusions: For patients who meet predefined criteria, retreatment with ipilimumab is generally well tolerated and can translate into clinical benefit. This strategy should be compared with other therapeutic options in randomised controlled trials. PMID:24619072

  9. Impact of different file systems on the amount of apically extruded debris during endodontic retreatment

    PubMed Central

    Uzunoglu, Emel; Turker, Sevinc Aktemur

    2016-01-01

    Objective: The goal of present study was to determine the effect of different nickel–titanium file systems on the amount of apically extruded debris during endodontic retreatment: D-RaCe retreatment systems, EdgeFile XR retreatment rotary files, and Reciproc R40. Materials and Methods: Thirty-six single-rooted prepared mandibular premolar teeth were filled with Gutta-percha and AH Plus sealer. The teeth were then randomly assigned into three groups (n = 12) for retreatment. The endodontic retreatment was performed as follows: D-RaCe, EdgeFile XR, Reciproc 40. Debris extruded apically during the retreatment was collected into preweighed Eppendorf tubes. An incubator was used to store tubes at 70° C for 5 days. The initial weight was subtracted from final weight of the Eppendorf tubes to calculate the weight of the dry extruded debris for each group. The data obtained were evaluated using Welch analysis of variance and Games-Howell post-hoc tests (P < 0.05). Results: All files resulted in apical extrusion of debris. Reciproc caused significantly less debris extrusion compared to D-RaCe and EdgeFile XR (P < 0.05). Conclusions: The findings revealed that during endodontic retreatment, number, and taper of files might have an influence on the amount of apically extruded debris during endodontic retreatment. PMID:27095898

  10. The Rhetoric of Strategic Retreat: Carter and the Panama Canal Debate.

    ERIC Educational Resources Information Center

    Sudol, Ronald A.

    1979-01-01

    Discusses President Carter's televised address on the Panama Canal Treaties in terms of five "topoi" for a rhetoric of retreat: timeliness, urgency, value, advantage, and shrewdness. Compares his failure to employ the commonsense arguments that a policy of retreat requires in the televised speech with his more successful impromptu speeches. (JMF)

  11. Timing of ice retreat alters seabird abundances and distributions in the southeast Bering Sea.

    PubMed

    Renner, Martin; Salo, Sigrid; Eisner, Lisa B; Ressler, Patrick H; Ladd, Carol; Kuletz, Kathy J; Santora, Jarrod A; Piatt, John F; Drew, Gary S; Hunt, George L

    2016-09-01

    Timing of spring sea-ice retreat shapes the southeast Bering Sea food web. We compared summer seabird densities and average bathymetry depth distributions between years with early (typically warm) and late (typically cold) ice retreat. Averaged over all seabird species, densities in early-ice-retreat-years were 10.1% (95% CI: 1.1-47.9%) of that in late-ice-retreat-years. In early-ice-retreat-years, surface-foraging species had increased numbers over the middle shelf (50-150 m) and reduced numbers over the shelf slope (200-500 m). Pursuit-diving seabirds showed a less clear trend. Euphausiids and the copepod Calanus marshallae/glacialis were 2.4 and 18.1 times less abundant in early-ice-retreat-years, respectively, whereas age-0 walleye pollock Gadus chalcogrammus near-surface densities were 51× higher in early-ice-retreat-years. Our results suggest a mechanistic understanding of how present and future changes in sea-ice-retreat timing may affect top predators like seabirds in the southeastern Bering Sea.

  12. Timing of ice retreat alters seabird abundances and distributions in the southeast Bering Sea.

    PubMed

    Renner, Martin; Salo, Sigrid; Eisner, Lisa B; Ressler, Patrick H; Ladd, Carol; Kuletz, Kathy J; Santora, Jarrod A; Piatt, John F; Drew, Gary S; Hunt, George L

    2016-09-01

    Timing of spring sea-ice retreat shapes the southeast Bering Sea food web. We compared summer seabird densities and average bathymetry depth distributions between years with early (typically warm) and late (typically cold) ice retreat. Averaged over all seabird species, densities in early-ice-retreat-years were 10.1% (95% CI: 1.1-47.9%) of that in late-ice-retreat-years. In early-ice-retreat-years, surface-foraging species had increased numbers over the middle shelf (50-150 m) and reduced numbers over the shelf slope (200-500 m). Pursuit-diving seabirds showed a less clear trend. Euphausiids and the copepod Calanus marshallae/glacialis were 2.4 and 18.1 times less abundant in early-ice-retreat-years, respectively, whereas age-0 walleye pollock Gadus chalcogrammus near-surface densities were 51× higher in early-ice-retreat-years. Our results suggest a mechanistic understanding of how present and future changes in sea-ice-retreat timing may affect top predators like seabirds in the southeastern Bering Sea. PMID:27651532

  13. Regional and global forcing of glacier retreat during the last deglaciation.

    PubMed

    Shakun, Jeremy D; Clark, Peter U; He, Feng; Lifton, Nathaniel A; Liu, Zhengyu; Otto-Bliesner, Bette L

    2015-08-21

    The ongoing retreat of glaciers globally is one of the clearest manifestations of recent global warming associated with rising greenhouse gas concentrations. By comparison, the importance of greenhouse gases in driving glacier retreat during the most recent deglaciation, the last major interval of global warming, is unclear due to uncertainties in the timing of retreat around the world. Here we use recently improved cosmogenic-nuclide production-rate calibrations to recalculate the ages of 1,116 glacial boulders from 195 moraines that provide broad coverage of retreat in mid-to-low-latitude regions. This revised history, in conjunction with transient climate model simulations, suggests that while several regional-scale forcings, including insolation, ice sheets and ocean circulation, modulated glacier responses regionally, they are unable to account for global-scale retreat, which is most likely related to increasing greenhouse gas concentrations.

  14. Regional and global forcing of glacier retreat during the last deglaciation

    PubMed Central

    Shakun, Jeremy D.; Clark, Peter U.; He, Feng; Lifton, Nathaniel A.; Liu, Zhengyu; Otto-Bliesner, Bette L.

    2015-01-01

    The ongoing retreat of glaciers globally is one of the clearest manifestations of recent global warming associated with rising greenhouse gas concentrations. By comparison, the importance of greenhouse gases in driving glacier retreat during the most recent deglaciation, the last major interval of global warming, is unclear due to uncertainties in the timing of retreat around the world. Here we use recently improved cosmogenic-nuclide production-rate calibrations to recalculate the ages of 1,116 glacial boulders from 195 moraines that provide broad coverage of retreat in mid-to-low-latitude regions. This revised history, in conjunction with transient climate model simulations, suggests that while several regional-scale forcings, including insolation, ice sheets and ocean circulation, modulated glacier responses regionally, they are unable to account for global-scale retreat, which is most likely related to increasing greenhouse gas concentrations. PMID:26293133

  15. Regional and global forcing of glacier retreat during the last deglaciation.

    PubMed

    Shakun, Jeremy D; Clark, Peter U; He, Feng; Lifton, Nathaniel A; Liu, Zhengyu; Otto-Bliesner, Bette L

    2015-01-01

    The ongoing retreat of glaciers globally is one of the clearest manifestations of recent global warming associated with rising greenhouse gas concentrations. By comparison, the importance of greenhouse gases in driving glacier retreat during the most recent deglaciation, the last major interval of global warming, is unclear due to uncertainties in the timing of retreat around the world. Here we use recently improved cosmogenic-nuclide production-rate calibrations to recalculate the ages of 1,116 glacial boulders from 195 moraines that provide broad coverage of retreat in mid-to-low-latitude regions. This revised history, in conjunction with transient climate model simulations, suggests that while several regional-scale forcings, including insolation, ice sheets and ocean circulation, modulated glacier responses regionally, they are unable to account for global-scale retreat, which is most likely related to increasing greenhouse gas concentrations. PMID:26293133

  16. Multi-temporal retreat rates along the eastern Mediterranean coastal cliff

    NASA Astrophysics Data System (ADS)

    Katz, O.; Mushkin, A.

    2012-12-01

    The Israeli coastal cliff extends about 50 km along the eastern Mediterranean shores. The cliff is comprised of late Quaternary eolianites and paleosols and reaches heights of up to 50 meters. In places, time-averaged inland cliff-top retreat rates of up to a few tens of centimeters per year have been measured usually by comparing aerial photos from the last decades. Commonly, these locally constrained retreat rates have been: 1) extrapolated as representative of the entire cliff length, and 2) adopted by hazard-mitigation and planning authorities. Here, we re-evaluate the current understanding of coastal-retreat patterns and rates along Israel's Mediterranean cliff line using a suite of field observations, aerial photography and recently obtained airborne and ground based high resolution LiDAR measurement of cliff morphologies. First, we constrain the decadal-scale retreat rates along the coastal-cliff by comparing the cliff-top location in 1945 and 2004 using aerial photos. We find a statistically significant spatial correlation between: 1) calculated low retreat rates (less than 0.1 m/yr) and field-based criteria indicating overall stability: slope angle of 45 deg. and talus cover along the lower part of the cliff and developed vegetation cover, and 2) high retreat rates and field criteria indicating recent instability: fresh landslide scars and 'hanging' valleys, which provides independent support for the calculated retreat rates. Calculated 60 years average cliff-top retreat rates of less than 0.1, 0.2 and 0.3 m/yr along 58%, 77% and 85% of the cliff length, respectively, reveal that extended stretches of the cliff line did not experience detectable retreat in the past 60 years, thus implying relative stability of 50% of Israel's costal cliffs during this time period. Second, we constrain the annual retreat rates using repeat high-resolution ground based LiDAR surveys before and after an extreme winter storm that occurred in Dec. 2010. Locally, storm induced

  17. Mentored residential writing retreats: a leadership strategy to develop skills and generate outcomes in writing for publication.

    PubMed

    Jackson, Debra

    2009-01-01

    There is an increasing expectation that academic and clinical nurses will contribute to disciplinary and professional discourses through scholarly writing. However, the difficulties and challenges associated with writing for publication mean that many papers will never be written. This current paper describes an innovative approach developed to support skill development and outcomes in writing for publication. Intensive residential writing retreats informed by the principles of servant leadership and incorporating strategies such as mentoring and peer learning were conducted in 2005 and 2007. Positive outcomes and benefits included publications submitted to peer-reviewed journals, as well as positive effects on collegial relationships, and team building. Novice writers benefited from intensive and sustained support and coaching by experienced writers. Organisational benefits included increased participation by staff and research higher degree students in publication activities, enhanced collegial relationships and opportunities for senior established writers to work with inexperienced writers.

  18. Rapid last-deglacial thinning and retreat of the marine-terminating southwestern Greenland ice sheet

    NASA Astrophysics Data System (ADS)

    Winsor, Kelsey; Carlson, Anders E.; Caffee, Marc W.; Rood, Dylan H.

    2015-09-01

    Marine-terminating outlet glaciers are a major source of modern ice loss from the Greenland Ice Sheet (GrIS), but their role in GrIS retreat during the last deglaciation is not well constrained. Here, we develop deglacial outlet glacier retreat chronologies for four regions in southwest and south Greenland to improve understanding of spatial variations in centennial- to millennial-scale ice loss under a warming climate. We calculate 10Be surface exposure ages of boulders located in fjords near the towns of Qaqortoq, Paamiut, Nuuk, and Sisimiut. Our northernmost study site, Sisimiut, deglaciated earliest at ∼18 ka to ∼15 ka with an average thinning rate of 0.1-0.3 m yr-1. Inland retreat from Sisimiut to the modern ice margin took ∼7 ka at an average retreat rate of 15-20 m yr-1. A 10Be-dated moraine ∼25 km from the modern GrIS margin deposited at ∼8 ka suggests a possible ice-margin still-stand, but this does not change overall retreat rates. After retreat from the small coastal Sisimiut fjords, the GrIS margin was mainly land-terminating in this region. In contrast, earliest exposure occurred at ∼12 ka near Qaqortoq, and 11-10 ka near Nuuk and Paamiut, with ice thinning at rates of 0.2-0.3 m yr-1 to instantaneous within measurement uncertainty. Ice retreat inland through the extensive Nuuk, Paamiut, and Qaqortoq fjord systems to near modern ice margins occurred in <1 ka, resulting in minimum retreat rates of 25-65 m yr-1 and maximum retreat rates of ∼95 m yr-1 to instantaneous within the uncertainty of our measurements. This rapid thinning and retreat of marine-terminating southwest GrIS margins is contemporaneous with an incursion of relatively warm ocean waters into the Labrador Sea and toward the southwest Greenland coast, suggesting that a warming ocean may have contributed to the more rapid retreat of marine GrIS termini in the Nuuk, Paamiut, and Qaqortoq fjord systems relative to the slower ice retreat inland from Sisimiut. Our results highlight

  19. Do rapidly retreating valley glaciers increase catchment sediment export rates?

    NASA Astrophysics Data System (ADS)

    Lane, Stuart; Bakker, Maarten; Gabbud, Chrystelle; Micheletti, Natan; Saugy, Jean-Noël

    2016-04-01

    In the face of rapid climate warming, rapid glacier recession should lead to a marked increase in the spatial extent of paraglacial processes operating in glaciated drainage basins. The paraglacial phase has been well established to be transient but there are very few studies of this transient response and what it means for sediment export. There is good reason to expect that glacier recession could increase basin-scale sediment connectivity as: sediment becomes less dependent on glacier surface transport; proglacial streams are more able to migrate laterally than subglacial streams and so access sediment for transport; and glacier debuttressing may aid the development of gullies that can dissect moraines and so aid hillslope to proglacial zone connectivity. By using records of the flushing of hydroelectric power installations we were able to develop a record of coarse sediment (sand and gravel) export from a basin with a rapidly retreating valley glacier, the Haut Glacier d'Arolla, from 1977 to 2014. Modelling suggested that these data could only be partially controlled by transport capacity implying an important role for sediment supply and potentially for the influence of changing sediment connectivity. Indeed, there was evidence of the effects of glacial debuttressing upon gullying processes and hence a possible increase in the ease of connection of upstream basins to the proglacial area. More recently, it was possible to show possible temperature control on sediment export, which may only have become apparent because of the progressive development of better sediment connectivity. However, whilst rapid glacier recession should result in theory in a progressive increase in connectivity of sediment sources to the basin outlet, the supply to capacity ratio does not increase continually with glacier recession until maximum capacity is reached. We identify two examples of why. First, gullying was also accompanied by the sediment accumulation at the base of moraines

  20. Glacier retreat and projected river regime changes in the hydrologically highly-coupled Virkisjökull catchment, Iceland

    NASA Astrophysics Data System (ADS)

    Flett, Verity; Kirkbride, Martin; Black, Andrew; Everest, Jez; MacDonald, Alan

    2016-04-01

    Virkisjökull, an outlet glacier of the Oræfajökull icecap in SE Iceland, currently has 60% glacier cover, though this is reducing due to glacier retreat. Intensive monitoring over the last 4 years includes measurement of measuring ice ablation, proglacial discharge, dye-tracing of flow pathways, and deployment of three automatic weather stations at altitudes up to 880 m. These data calibrate a distributed hydrological model (WaSIM) to project potential river regime during stages of glacier retreat. Results show: (1) glacier hypsometry sensitises the catchment to a disproportionately rapid increase in runoff as the snowline rises onto a gentle ice cap resulting in in a potential annual increase in river discharge of up to 37% (2) a dominantly channelized glacial drainage system in all seasons with a rapid runoff response to melt: englacial flow of 0.58 m s-1 is comparable to the proglacial river velocity; and (3) longer-term, reduced glacier cover and snow storage will lead to a discharge regime dominated by short-term precipitation events in all seasons, and a reduced influence of the seasonal meltwater discharge peak. The study demonstrates the importance of glacier hypsometry above the present ELA as an influence on catchment hydrological response to potential climate warming.

  1. Extinction and ecological retreat in a community of primates.

    PubMed

    Crowley, Brooke E; Godfrey, Laurie R; Guilderson, Thomas P; Zermeño, Paula; Koch, Paul L; Dominy, Nathaniel J

    2012-09-01

    The lemurs of Madagascar represent a prodigious adaptive radiation. At least 17 species ranging from 11 to 160 kg have become extinct during the past 2000 years. The effect of this loss on contemporary lemurs is unknown. The concept of competitive release favours the expansion of living species into vacant niches. Alternatively, factors that triggered the extinction of some species could have also reduced community-wide niche breadth. Here, we use radiocarbon and stable isotope data to examine temporal shifts in the niches of extant lemur species following the extinction of eight large-bodied species. We focus on southwestern Madagascar and report profound isotopic shifts, both from the time when now-extinct lemurs abounded and from the time immediately following their decline to the present. Unexpectedly, the past environments exploited by lemurs were drier than the protected (albeit often degraded) riparian habitats assumed to be ideal for lemurs today. Neither competitive release nor niche contraction can explain these observed trends. We develop an alternative hypothesis: ecological retreat, which suggests that factors surrounding extinction may force surviving species into marginal or previously unfilled niches.

  2. The 20th Annual Prostate Cancer Foundation Scientific Retreat report.

    PubMed

    Miyahira, Andrea K; Simons, Jonathan W; Soule, Howard R

    2014-06-01

    The 20th Annual Prostate Cancer Foundation (PCF) Scientific Retreat was held from October 24 to 26, 2013, in National Harbor, Maryland. This event is held annually for the purpose of convening a diverse group of leading experimental and clinical researchers from academia, industry, and government to present and discuss critical and emerging topics relevant to prostate cancer (PCa) biology, and the diagnosis, prognosis, and treatment of PCa patients, with a focus on results that will lend to treatments for the most life-threatening stages of this disease. The themes that were highlighted at this year's event included: (i) mechanisms of PCa initiation and progression: cellular origins, neurons and neuroendocrine PCa, long non-coding RNAs, epigenetics, tumor cell metabolism, tumor-immune interactions, and novel molecular mechanisms; (ii) advancements in precision medicine strategies and predictive biomarkers of progression, survival, and drug sensitivities, including the analysis of circulating tumor cells and cell-free tumor DNA-new methods for liquid biopsies; (iii) new treatments including epigenomic therapy and immunotherapy, discovery of new treatment targets, and defining and targeting mechanisms of resistance to androgen-axis therapeutics; and (iv) new experimental and clinical epidemiology methods and techniques, including PCa population studies using patho-epidemiology.

  3. Extinction and ecological retreat in a community of primates.

    PubMed

    Crowley, Brooke E; Godfrey, Laurie R; Guilderson, Thomas P; Zermeño, Paula; Koch, Paul L; Dominy, Nathaniel J

    2012-09-01

    The lemurs of Madagascar represent a prodigious adaptive radiation. At least 17 species ranging from 11 to 160 kg have become extinct during the past 2000 years. The effect of this loss on contemporary lemurs is unknown. The concept of competitive release favours the expansion of living species into vacant niches. Alternatively, factors that triggered the extinction of some species could have also reduced community-wide niche breadth. Here, we use radiocarbon and stable isotope data to examine temporal shifts in the niches of extant lemur species following the extinction of eight large-bodied species. We focus on southwestern Madagascar and report profound isotopic shifts, both from the time when now-extinct lemurs abounded and from the time immediately following their decline to the present. Unexpectedly, the past environments exploited by lemurs were drier than the protected (albeit often degraded) riparian habitats assumed to be ideal for lemurs today. Neither competitive release nor niche contraction can explain these observed trends. We develop an alternative hypothesis: ecological retreat, which suggests that factors surrounding extinction may force surviving species into marginal or previously unfilled niches. PMID:22628463

  4. Semantics versus statistics in the retreat from locative overgeneralization errors.

    PubMed

    Ambridge, Ben; Pine, Julian M; Rowland, Caroline F

    2012-05-01

    The present study investigated how children learn that some verbs may appear in the figure-locative but not the ground-locative construction (e.g., Lisa poured water into the cup; *Lisa poured the cup with water), with some showing the opposite pattern (e.g., *Bart filled water into the cup; Bart filled the cup with water), and others appearing in both (Lisa sprayed water onto the flowers; Lisa sprayed the flowers with water). Grammatical acceptability judgments were obtained for the use of each of 142 locative verbs (60 for children) in each sentence type. Overall, and for each age group individually, the judgment data were best explained by a model that included ratings of the extent to which each verb exhibits both the broad- and narrow-range semantic properties of the figure- and ground-locative constructions (relating mainly to manner and end-state respectively; Pinker, 1989) and the statistical-learning measure of overall verb frequency (entrenchment; Braine & Brooks, 1995). A second statistical-learning measure, frequency in each of the two locative constructions (pre-emption; Goldberg, 1995), was found to have no additional dissociable effect. We conclude by drawing together various theoretical proposals to arrive at a possible account of how semantics and statistics interact in the retreat from overgeneralization.

  5. In Review (Geology): Alpine Landscape Evolution Dominated by Cirque Retreat

    NASA Technical Reports Server (NTRS)

    Oskin, Michael; Burbank, Doug

    2005-01-01

    Despite the abundance in alpine terrain of glacially dissected landscapes, the magnitude and geometry of glacial erosion can rarely be defined. In the eastern Kyrgyz Range, a widespread unconformity exhumed as a geomorphic surface provides a regional datum with which to calibrate erosion. As tectonically driven surface uplift has progressively pushed this surface into the zone of ice accumulation, glacial erosion has overprinted the landscape. With as little as 500 m of incision into rocks underlying the unconformity, distinctive glacial valleys display their deepest incision adjacent to cirque headwalls. The expansion of north-facing glacial cirques at the expense of south-facing valleys has driven the drainage divide southwards at rates up to 2 to 3 times the rate of valley incision. Existing ice-flux-based glacial erosion rules incompletely model expansion of glacial valleys via cirque retreat into the low-gradient unconformity remnants. Local processes that either directly sap cirque headwalls or inhibit erosion down-glacier appear to control, at least initially, alpine landscape evolution.

  6. Paludification and forest retreat in northern oceanic environments.

    PubMed

    Crawford, R M M; Jeffree, C E; Rees, W G

    2003-01-01

    Examination of temperature variations over the past century for Europe and the Arctic from northern Norway to Siberia suggests that variations in the North Atlantic Oscillation are associated with an increase in oceanicity in certain maritime regions. A southward depression of the tree line in favour of wet heaths, bogs and wetland tundra communities is also observed in northern oceanic environments. The physiological basis for this change in ecological succession from forest to bog is discussed in relation to the long-term effects of flooding on tree survival. The heightened values currently detected in the North Atlantic Oscillation Index, together with rising winter temperatures, and increased rainfall in many areas in northern Europe, presents an increasing risk of paludification with adverse consequences for forest regeneration, particularly in areas with oceanic climates. Climatic warming in oceanic areas may increase the area covered by bogs and, contrary to general expectations, lead to a retreat rather than an advance in the northern limit of the boreal forest. High water-table levels are not automatically detrimental to forest survival as can be seen in swamp, bottom land and mangrove forests. Consequently, the inhibitory effects of flooding on tree survival and regeneration in northern regions should not be uncritically accepted as merely due to high water levels. Evidence is discussed which suggests that physiological and ecological factors may interact to inhibit forest regeneration in habitats where there is a risk of prolonged winter-flooding combined with warmer winters and cool moist summers.

  7. The unsteady nature of sea cliff retreat due to mechanical abrasion, failure and comminution feedbacks

    NASA Astrophysics Data System (ADS)

    Kline, Shaun W.; Adams, Peter N.; Limber, Patrick W.

    2014-08-01

    Sea cliff retreat is often linked to large waves, heavy precipitation and seismic events, but the specific operative mechanics have not been well constrained. In particular, what is the role of mechanical abrasion by beach sediments in cliff/platform evolution and how does it relate to the episodic nature of cliff retreat observed at certain locations? Here we present a simple, numerical model of sea cliff retreat that incorporates mechanical abrasion of a basal notch, threshold-controlled failure of the cantilevered block, and a feedback mechanism wherein retreat is dependent on the rate of sediment comminution within the surf zone. Using shore platform and cliff characteristics found in two coastal settings (the central California coast and the English North Sea coast), the model produces retreat rates comparable to those observed via field measurements. The highest retreat rates coincide with the steepest shore platforms and increasing wave height. Steeper platforms promote wave access to the cliff toe and, correspondingly, the receding cliff face produces additional accommodation space for the platform beach, preserving the erosive efficacy of the beach sediments. When exposed to energetic wave forcing, the slope of the inner platform segment controls retreat rates for concave platforms, whereas the slope of the outer platform segment exerts greater control for convex platforms. Platform beaches approached a long-term dynamic equilibrium on the concave profiles, leading to more consistent and steady retreat. Platform beaches were ephemeral on convex profiles, mirroring observed sand wave (Ord) migration on the Holderness coast, UK. These findings agree with previous field observations and support mechanical abrasion as a viable cause of temporal heterogeneity in cliff retreat rate for both coastlines.

  8. Adolescent-evaluated quality of life: a longitudinal study.

    PubMed

    Ward-Smith, Peggy; McCaskie, Becki; Rhoton, Shannon

    2007-01-01

    Opportunities for adolescents with cancer to interact with each other are few. This project provided a weekend retreat for adolescents with cancer and obtained longitudinal self-evaluated quality of life data. Data were collected using the Adolescent Quality of Life instrument, which is a 16-item Likert-scaled survey that assesses quality of life. Twenty-two adolescents attended the weekend, and 17 participated in the study. Evaluations of the weekend retreat were positive, with "making friends" and "meeting others like me" the most frequent comments. Data from the Adolescent Quality of Life instrument revealed that for this population, quality of life was unchanged directly after the weekend and was statistically worse 1 month later. Enrollment methods skewed study participation toward individuals receiving treatment, which may explain these results. The reliability of the Adolescent Quality of Life instrument remained stable over time, and it appears to accurately assess and reflect changes in quality of life.

  9. High mortality associated with retreatment of tuberculosis in a clinic in Kampala, Uganda: a retrospective study.

    PubMed

    Acuña-Villaorduña, Carlos; Ayakaka, Irene; Dryden-Peterson, Scott; Nakubulwa, Susan; Worodria, William; Reilly, Nancy; Hosford, Jennifer; Fennelly, Kevin P; Okwera, Alphonse; Jones-López, Edward C

    2015-07-01

    The World Health Organization recommends for tuberculosis retreatment a regimen of isoniazid (H), rifampicin (R), ethambutol (E), pyrazinamide (Z), and streptomycin (S) for 2 months, followed by H, R, E, and Z for 1 month and H, R, and E for 5 months. Using data from the National Tuberculosis and Leprosy Program registry, this study determined the long-term outcome under programmatic conditions of patients who were prescribed the retreatment regimen in Kampala, Uganda, between 1997 and 2003. Patients were traced to determine their vital status; 62% (234/377) patients were found dead. Having ≤ 2 treatment courses and not completing retreatment were associated with mortality in adjusted analyses.

  10. Clinical microscopic analysis of ProTaper retreatment system efficacy considering root canal thirds using three endodontic sealers.

    PubMed

    Só, Marcus Vinícius Reis; De Figueiredo, Jose Antônio Poli; Freitas Fachin, Elaine Vianna; Húngaro Duarte, Marco Antônio; Pereira, Jefferson Ricardo; Kuga, Milton Carlos; Da Rosa, Ricardo Abreu

    2012-09-01

    To evaluate the efficacy of ProTaper Universal rotary retreatment system and the influence of sealer type on the presence of filling debris in the reinstrumented canals viewed in an operative clinical microscope. Forty-five palatal root canals of first molars were filled with gutta-percha and one of the following sealers: G1, EndoFill; G2, AH Plus; G3, Sealapex. The canals were then reinstrumented with ProTaper Universal rotary system. Roots were longitudinally sectioned and examined under an operative clinical microscope (10×), and the amount of filling debris on canal walls was analyzed using the AutoCAD 2004 software. A single operator used a specific software tool to outline the canal area and the filling debris area in each third (cervical, middle, and apical), as well as the total canal area. Data were analyzed by Kruskal-Wallis test and Tukey test at P < 0.05. Sealapex demonstrated significant differences in the average of filling debris area/canal among the 3 thirds. This group revealed that apical third showed more debris than the both cervical and middle third (P < 0.0001). Endofill presented significantly more filling debris than Sealapex in the cervical third (P < 0.05). In the middle (P = 0.12) and apical third (P = 0.10), there were no differences amongst groups. Debris was left in all canal thirds, regardless of the retreatment technique. The greatest differences between techniques and sealers were found in the cervical third. PMID:22496039

  11. Irradiation and Bevacizumab in High-Grade Glioma Retreatment Settings

    SciTech Connect

    Niyazi, Maximilian; Ganswindt, Ute; Schwarz, Silke Birgit; Kreth, Friedrich-Wilhelm; Tonn, Joerg-Christian; Geisler, Julia; Fougere, Christian la; Ertl, Lorenz; Linn, Jennifer; Siefert, Axel; Belka, Claus

    2012-01-01

    Purpose: Reirradiation is a treatment option for recurrent high-grade glioma with proven but limited effectiveness. Therapies directed against vascular endothelial growth factor have been shown to exert certain efficacy in combination with chemotherapy and have been safely tested in combination with radiotherapy in a small cohort of patients. To study the feasibility of reirradiation combined with bevacizumab treatment, the toxicity and treatment outcomes of this approach were analyzed retrospectively. Patients and Methods: After previous treatment with standard radiotherapy (with or without temozolomide) patients with recurrent malignant glioma received bevacizumab (10 mg/kg intravenous) on Day 1 and Day 15 during radiotherapy. Maintenance therapy was selected based on individual considerations, and mainly bevacizumab-containing regimens were chosen. Patients received 36 Gy in 18 fractions. Results: The data of the medical charts of the 30 patients were analyzed retrospectively. All were irradiated in a single institution and received either bevacizumab (n = 20), no additional substance (n = 7), or temozolomide (n = 3). Reirradiation was tolerated well, regardless of the added drug. In 1 patient treated with bevacizumab, a wound dehiscence occurred. Overall survival was significantly better in patients receiving bevacizumab (p = 0.03, log-rank test). In a multivariate proportional hazards Cox model, bevacizumab, Karnovsky performance status, and World Health Organization grade at relapse turned out to be the most important predictors for overall survival. Conclusion: Reirradiation with bevacizumab is a feasible and effective treatment for patients with recurrent high-grade gliomas. A randomized trial is warranted to finally answer the question whether bevacizumab adds substantial benefit to a radiotherapeutic retreatment setting.

  12. Reconsidering the Significance of Subaerial Processes in Streambank Retreat

    NASA Astrophysics Data System (ADS)

    Wynn, T. M.; Henderson, M. B.; Staley, N. A.

    2006-12-01

    Subaerial processes, such as freeze-thaw cycling and desiccation cracking, increase streambank retreat by reducing soil strength and directly inducing soil erosion. To date, the effects of subaerial processes have been largely dismissed in stream channel erosion models, both at the reach-scale and watershed-scale. Results from recent field and modeling research in southwestern Virginia indicate subaerial processes are a dominant erosion process in small headwater streams in the mid-Atlantic US. In situ tests of streambank soil erodibility (k) showed the median k in the winter was 1.4 times greater than in spring or fall and 75 percent greater than in summer (p=0.024). The median summer k was 37 percent higher than in spring/fall. Regression analysis using measurements of streambank surface moisture content and temperature indicated over 70 percent of the variance in k measurements was explained by the number of freeze-thaw cycles occurring in the 30 days prior to field testing. In comparing both watershed-scale (SWAT and GWLF) and reach-scale (CONCEPTS) model estimates of streambank soil loss to field measurements using erosion pins, the models failed to simulate significant erosion rates that occurred during January 2006. This inconsistency was attributed to the lack of subaerial process routines in the models. A history of poor agricultural and silvicultural practices and the widespread presence of small mill dams in the Piedmont and Appalachian mountains in the 1800s created floodplain soils composed largely of silts. Considering the susceptibility of silty soils to degradation by freeze-thaw cycling and the temperate climate of the mid-Atlantic with cold winters and hot summers, subaerial processes may be a significant mechanism for stream channel degradation in the region.

  13. Glacier retreat in New Zealand during the Younger Dryas stadial.

    PubMed

    Kaplan, Michael R; Schaefer, Joerg M; Denton, George H; Barrell, David J A; Chinn, Trevor J H; Putnam, Aaron E; Andersen, Bjørn G; Finkel, Robert C; Schwartz, Roseanne; Doughty, Alice M

    2010-09-01

    Millennial-scale cold reversals in the high latitudes of both hemispheres interrupted the last transition from full glacial to interglacial climate conditions. The presence of the Younger Dryas stadial (approximately 12.9 to approximately 11.7 kyr ago) is established throughout much of the Northern Hemisphere, but the global timing, nature and extent of the event are not well established. Evidence in mid to low latitudes of the Southern Hemisphere, in particular, has remained perplexing. The debate has in part focused on the behaviour of mountain glaciers in New Zealand, where previous research has found equivocal evidence for the precise timing of increased or reduced ice extent. The interhemispheric behaviour of the climate system during the Younger Dryas thus remains an open question, fundamentally limiting our ability to formulate realistic models of global climate dynamics for this time period. Here we show that New Zealand's glaciers retreated after approximately 13 kyr bp, at the onset of the Younger Dryas, and in general over the subsequent approximately 1.5-kyr period. Our evidence is based on detailed landform mapping, a high-precision (10)Be chronology and reconstruction of former ice extents and snow lines from well-preserved cirque moraines. Our late-glacial glacier chronology matches climatic trends in Antarctica, Southern Ocean behaviour and variations in atmospheric CO(2). The evidence points to a distinct warming of the southern mid-latitude atmosphere during the Younger Dryas and a close coupling between New Zealand's cryosphere and southern high-latitude climate. These findings support the hypothesis that extensive winter sea ice and curtailed meridional ocean overturning in the North Atlantic led to a strong interhemispheric thermal gradient during late-glacial times, in turn leading to increased upwelling and CO(2) release from the Southern Ocean, thereby triggering Southern Hemisphere warming during the northern Younger Dryas.

  14. Glacier retreat in New Zealand during the Younger Dryas stadial.

    PubMed

    Kaplan, Michael R; Schaefer, Joerg M; Denton, George H; Barrell, David J A; Chinn, Trevor J H; Putnam, Aaron E; Andersen, Bjørn G; Finkel, Robert C; Schwartz, Roseanne; Doughty, Alice M

    2010-09-01

    Millennial-scale cold reversals in the high latitudes of both hemispheres interrupted the last transition from full glacial to interglacial climate conditions. The presence of the Younger Dryas stadial (approximately 12.9 to approximately 11.7 kyr ago) is established throughout much of the Northern Hemisphere, but the global timing, nature and extent of the event are not well established. Evidence in mid to low latitudes of the Southern Hemisphere, in particular, has remained perplexing. The debate has in part focused on the behaviour of mountain glaciers in New Zealand, where previous research has found equivocal evidence for the precise timing of increased or reduced ice extent. The interhemispheric behaviour of the climate system during the Younger Dryas thus remains an open question, fundamentally limiting our ability to formulate realistic models of global climate dynamics for this time period. Here we show that New Zealand's glaciers retreated after approximately 13 kyr bp, at the onset of the Younger Dryas, and in general over the subsequent approximately 1.5-kyr period. Our evidence is based on detailed landform mapping, a high-precision (10)Be chronology and reconstruction of former ice extents and snow lines from well-preserved cirque moraines. Our late-glacial glacier chronology matches climatic trends in Antarctica, Southern Ocean behaviour and variations in atmospheric CO(2). The evidence points to a distinct warming of the southern mid-latitude atmosphere during the Younger Dryas and a close coupling between New Zealand's cryosphere and southern high-latitude climate. These findings support the hypothesis that extensive winter sea ice and curtailed meridional ocean overturning in the North Atlantic led to a strong interhemispheric thermal gradient during late-glacial times, in turn leading to increased upwelling and CO(2) release from the Southern Ocean, thereby triggering Southern Hemisphere warming during the northern Younger Dryas. PMID

  15. Why is there no Universal Law for Rock Wall Retreat?

    NASA Astrophysics Data System (ADS)

    Krautblatter, Michael; Moore, Jeffrey

    2016-04-01

    Comparing studies of rock slope erosion and soil slope erosion, we find no governing equation similar to the universal soil loss equation for rock slopes. Rock masses in contact with the atmosphere are affected by a suite of physical, chemical and biological processes which degrade intact rock, creating new fractures and extending existing flaws. Complex feedbacks must be explored between changing slope boundary conditions, stress redistribution and fracturing, and weathering by external mechanisms. Rock slope systems are distinguished from soil slope systems by the fundamental nonlinear properties of rock masses. Rock masses represent discontinuous, inhomogeneous, anisotropic, and nonlinearly elastic materials, and contain a record of millions of years of thermal, hydrological, mechanical and chemical (THMC) processes. The origin and evolution of rock mass strength over time can significantly affect bedrock erodibility and engineering performance, the study of which represents a major chance and challenge for the geoscience community. The imprint of THMC processes on rock properties begins with the geological genesis of rocks; however, a significant degree of material behaviour evolves coincidently with the exhumation and evolution of topography. Thus, fracture generation has been investigated as the result of the environmental stress history in geology and geomorphology, partly modulated by incision and topographic stress evolution. Resultant fracture patterns control the degree of discontinuity heterogeneity, anisotropy, and nonlinear mechanical behaviour over millions of years. Here we discuss important novel conceptual approaches to temporally and spatially decipher nonlinear effects on rock slope erosion including incision-related topographic stresses, rock fatigue, paraglacial and paracratering effects etc. and how they could contribute to a more uniform understanding of rockwall retreat.

  16. Four-decade record of pervasive grounding line retreat along the Bellingshausen margin of West Antarctica

    NASA Astrophysics Data System (ADS)

    Christie, Frazer D. W.; Bingham, Robert G.; Gourmelen, Noel; Tett, Simon F. B.; Muto, Atsuhiro

    2016-06-01

    Changes to the grounding line, where grounded ice starts to float, can be used as a remotely sensed measure of ice-sheet susceptibility to ocean-forced dynamic thinning. Constraining this susceptibility is vital for predicting Antarctica's contribution to rising sea levels. We use Landsat imagery to monitor grounding line movement over four decades along the Bellingshausen margin of West Antarctica, an area little monitored despite potential for future ice losses. We show that ~65% of the grounding line retreated from 1990 to 2015, with pervasive and accelerating retreat in regions of fast ice flow and/or thinning ice shelves. Venable Ice Shelf confounds expectations in that, despite extensive thinning, its grounding line has undergone negligible retreat. We present evidence that the ice shelf is currently pinned to a sub-ice topographic high which, if breached, could facilitate ice retreat into a significant inland basin, analogous to nearby Pine Island Glacier.

  17. Antarctic marine ice sheet retreat in the Ross Sea during the early Holocene

    NASA Astrophysics Data System (ADS)

    Mckay, R. M.; Golledge, N.; Naish, T.; Maas, S.; Levy, R. H.; Kuhn, G.; Lee, J. I.; Dunbar, G. B.

    2015-12-01

    Geological constraints on the timing of the retreat of the Last Glacial Maximum (LGM) Antarctic Ice Sheets provide critical insights into the processes controlling marine-based ice sheet stability. The over-deepened, seaward shallowing bathymetry of Antarctica's continental shelves is ideally configured to promote past, and potentially future, marine ice-sheet instability. The retreat history of the LGM ice sheet in the Ross Sea region is primarily constrained by C-14 ages on coastal beach ridges and relict penguin colonies along the Transantarctic Mountain front in the Western Ross Sea. Although these terrestrial sites offer more reliable dates than imprecise C-14 chronologies derived from bulk marine sediments, they may reflect retreat of local piedmont glaciers derived from East Antarctic outlet glaciers rather than representing the timing of retreat of the ice sheet in the central Ross Embayment. We present a sedimentary facies succession and foraminifera-based C-14 chronology from a core collected beneath the Ross Ice Shelf via a hot water drill access hole used for the ANDRILL Coulman High site survey. The site is to the east of Ross Island and distal from the coast, and yields a minimum age for glacial retreat that is approximately 1000 yrs earlier than suggested by coastal records along the nearby Victoria Land coast. We examine the implications of this constraint on the timing of ice sheet retreat in the context of model simulations and new multi-beam bathymetry data acquired in the Western Ross Sea. On the basis of these data we hypothesize that marine-based ice sheet retreat was triggered by oceanic forcings along most of the Pacific Ocean coastline of Antarctica simultaneously, but continued retreat in the Ross Sea occurred primarily as a consequence of marine ice sheet instability.

  18. Multi-decadal retreat of Novaya Zemlya outlet glaciers, in response to climatic forcing

    NASA Astrophysics Data System (ADS)

    Carr, Rachel; Bell, Heather

    2016-04-01

    Arctic ice masses have rapidly lost ice from the mid-1990s, through a combination of negative surface mass balance and accelerated ice discharge from marine-terminating outlet glaciers. In the past decade, substantial mass deficits have been identified on Novaya Zemlya (NVZ), Russian High Arctic, and its outlet glaciers have retreated dramatically, likely due to declining sea ice concentrations. However, little is known about longer-term glacier behaviour on NVZ, and its potential impact on overall mass balance. Here we greatly extend the available record of retreat and assess multi-decadal glacier response to forcing between 1976 and 2014 using remotely sensed data. Following at least 25 years of gradual recession, retreat rates accelerated substantially from circa. 2000 and again from 2011 onwards. The rate and temporal pattern of retreat were strongly dependant on terminus type: marine-terminating outlets receded an order of magnitude faster than land- or lagoon-terminating glaciers and land-based termini showed limited change in retreat rate over time. Furthermore, retreat was markedly higher on the Barents Sea coast than the Kara Sea. Comparison with forcing data shows that accelerated retreat from 2011 onwards coincided with exceptionally low sea ice concentration and duration between 2011 and 2013. This suggests that sea ice is an important controlling factor, which agrees with shorter-term studies on NVZ. Although air temperature information is more limited on NVZ, data from both meteorological stations and reanalysis highlight 2011 and 2012 as two of the warmest years during the period 1950 to 2014. The limited response of land-terminating outlets suggests that air temperatures do not cause retreat directly, via melting or enhanced basal lubrication, but may have an indirect influence through melting of sea ice or hydro fracture.

  19. Retreat space and human visitor density moderate undesirable behavior in petting zoo animals.

    PubMed

    Anderson, Ursula S; Benne, Marcie; Bloomsmith, Mollie A; Maple, Terry L

    2002-01-01

    This study focused on the relationship between nonhuman animal behavior and envi-ronment- specifically, between the undesirable behavior exhibited by domestic pet-ting zoo animals in the presence of humans and the spatial design of the petting zoo environment. A spatial feature of a petting zoo referred to as a retreat space was ma-nipulated so that it affected the animals' opportunity for individual control over inter-action with humans. Three conditions were tested: no retreat space, semi-retreat space, and a full-retreat space. The subjects of this study were 5 African pygmy goats (Capra hircus) and 2 Romanov sheep (Ovis aries). Investigators used a focal sam-pling technique to analyze approximately 27 hr of behavioral data collected. The data were analyzed using multiple linear regression methods. The findings suggest that the full-retreat design beneficially moderated both sheep and goat behavior: Undesirable behaviors were lowest in the full-retreat condition. This study provides information that may improve human-animal interactions in a petting zoo setting and may in-crease animal well-being through exhibit design and management techniques. PMID:12738581

  20. A regional approach for modeling cliff retreat rate: The Makhteshim Country, Israel

    NASA Astrophysics Data System (ADS)

    Finzi, Yaron; Harlev, Noam

    2016-10-01

    Cliff retreat rate significantly affect the evolution of landforms and cliff stability. Cliff retreat studies also provide intriguing clues regarding past geomorphic conditions and environmental changes. We hereby present a model to calculate cliff retreat rate based on spatial data of cliff structure and morphology. The model is applied to numerous cliffs in the arid Makhteshim Country, Israel, and results are calibrated using published rates of two local cliffs. The calculated retreat rates confirm previous assertions that the crater cliffs are receding very slowly, but reveal that the rates vary significantly along the cliffs (1-18 cm ky- 1). Results also provide first estimates of retreat rates of other major cliffs in the region including fast retreat rates at the Sede Zin cliff (300-600 cm ky- 1). The proposed model provides a robust analysis to account for local cliff-talus morphology and yields rate estimates representative of current conditions rather than a long-term (geologic) average rate. Results presented constitute important new insights into regional geomorphic processes and on the stability of specific cliff sections within the study area.

  1. Hot rocks or no hot rocks: overnight retreat availability and selection by a diurnal lizard.

    PubMed

    Sabo, John L

    2003-08-01

    I used radio telemetry to determine the effects of substrate size and composition on overnight retreat site selection by western fence lizards (Sceloporus occidentalis). In watersheds of northern California (USA), these lizards occupy two habitat types differing in substrate characteristics: rocky cobble bars found in the dry, active channels of rivers and grassy upland meadows. Rocky substrates, found almost exclusively on cobble bars, provided warmer potential retreat sites than all available retreat sites on meadows during the first 5 h of inactivity. Only cobble and sand substrates provided retreats with temperatures within the preferred daily active range (32-36 degrees C) during the inactive period for these lizards (1900-0900 hours). Females on a cobble bar used rocks as retreats on >90% of nights during the breeding season whereas females on a meadow used wood (>70% of nights) and burrows (>25% of nights). In contrast to females, cobble bar males used rocks significantly less frequently (<70%) and slept in the open air significantly more frequently (25% vs. <1%). Cobble bar females further, showed a significant preference for cobbles 15 cm thick, whereas the rocks used by males did not differ significantly in thickness from those measured in randomly placed transects. Rocks 15 cm thick were the warmest retreats commonly available on this habitat type. Thus, thermal microenvironments available to and chosen by gravid female lizards differ considerably between river and non-river habitats. PMID:12802672

  2. The effect of a power-law mantle viscosity on trench retreat rate

    NASA Astrophysics Data System (ADS)

    Holt, Adam F.; Becker, Thorsten W.

    2016-10-01

    The subduction of lithospheric plates is partitioned between subducting plate motion and lateral slab migration (i.e., trench retreat and advance). We use 3-D, dynamic models of subduction to address the role of a power-law mantle viscosity on subduction dynamics and, in particular, rates of trench retreat. For all numerical models tested, we find that a power-law rheology results in reduced rates of trench retreat, and elevated slab dip angles, relative to the equivalent isoviscous mantle model. We analyze the asthenospheric pressure distribution and the style of mantle flow, which exhibits only limited variability as a function of mantle rheology, in order to compute estimates of the mantle forces associated with subduction. The inclusion of a power-law rheology reduces the mantle shear force (which resists subducting plate motion) to a greater degree than it reduces the dynamic pressure gradient across the slab (which resists trench retreat). Therefore, the inclusion of a power-law mantle rheology favors a shift towards a subduction mode with a reduced trench retreat component, typically a relative reduction of order 25% in our 3-D models. We suggest that this mechanism may be of importance for reducing the high trench retreat rates observed in many previous models to levels more in line with the average subduction partitioning observed on Earth at present (i.e., trench velocity ≤ plate velocity), for most absolute plate motion reference frames.

  3. Using Survival Analysis to Identify Risk Factors for Treatment Interruption among New and Retreatment Tuberculosis Patients in Kenya

    PubMed Central

    Masini, Enos O.; Mansour, Omar; Speer, Clare E.; Addona, Vittorio; Hanson, Christy L.; Sitienei, Joseph K.; Kipruto, Hillary K.; Githiomi, Martin Muhingo; Mungai, Brenda Nyambura

    2016-01-01

    Despite high tuberculosis (TB) treatment success rate, treatment adherence is one of the major obstacles to tuberculosis control in Kenya. Our objective was to identify patient-related factors that were associated with time to TB treatment interruption and the geographic distribution of the risk of treatment interruption by county. Data of new and retreatment patients registered in TIBU, a Kenyan national case-based electronic data recording system, between 2013 and 2014 was obtained. Kaplan-Meier curves and log rank tests were used to assess the adherence patterns. Mixed-effects Cox proportional hazards modeling was used for multivariate analysis. Records from 90,170 patients were included in the study. The cumulative incidence of treatment interruption was 4.5% for new patients, and 8.5% for retreatment patients. The risk of treatment interruption was highest during the intensive phase of treatment. Having previously been lost to follow-up was the greatest independent risk factor for treatment interruption (HR: 4.79 [3.99, 5.75]), followed by being HIV-positive not on ART (HR: 1.96 [1.70, 2.26]) and TB relapse (HR: 1.70 [1.44, 2.00]). Male and underweight patients had high risks of treatment interruption (HR: 1.46 [1.35, 1.58]; 1.11 [1.03, 1.20], respectively). High rates of treatment interruption were observed in counties in the central part of Kenya while counties in the northeast had the lowest risk of treatment interruption. A better understanding of treatment interruption risk factors is necessary to improve adherence to treatment. Interventions should focus on patients during the intensive phase, patients who have previously been lost to follow-up, and promotion of integrated TB and HIV services among public and private facilities. PMID:27706230

  4. Focusing on Main Street's Problems from Secluded Laboratory Retreats

    ERIC Educational Resources Information Center

    Kushner, Lawrence M.

    1973-01-01

    A report on the National Bureau of Standards is presented. It provides national measurement standards for some 40 physical quantities related through the laws of physics to the basic six - length, time, mass, temperature, electric current, and luminous intensity. (DF)

  5. Small scale tests on the progressive retreat of soil slopes

    NASA Astrophysics Data System (ADS)

    Voulgari, Chrysoula; Utili, Stefano; Castellanza, Riccardo

    2015-04-01

    In this paper, the influence due to the presence of cracks on the morphologic evolution of natural cliffs subject to progressive retreat induced by weathering is investigated through small scale laboratory tests. Weathering turns hard rocks into soft rocks that maintain the structure of the intact rocks, but are characterised by higher void ratios and reduced bond strengths; soft rocks are transformed into granular soils generally called residual soils. A number of landslides develop in slopes due to weathering which results in the progressive retrogression of the slope face and the further degradation within the weathering zone. Cracks, that are widely present, can be a result of weathering and they can cause a significant decrease in their stability, as they provide preferential flow channels which increase the soil permeability and decrease the soil strength. The geological models employed until now are mainly empirical. Several researchers have tried to study the stability of slopes through experimental procedures. Centrifuge modelling is widely used to investigate the failure of slopes. Small scale tests are also an important approach, in order to study the behaviour of a slope under certain conditions, such as the existence of water, as they allow the observation of the infiltration processes, the movement of the weathering front, deformation and failure. However, the deformation response of a slope subject to weathering is not yet thoroughly clarified. In this work, a set of experiments were conducted to investigate weathering induced successive landslides. Weathering was applied to the slope model by wetting the slope crest through a rainfall simulator device. The moisture content of the soil during the tests was monitored by soil moisture sensors that were buried inside the slope model. High resolution cameras were recording the behaviour of the slope model. GeoPIV was used to analyse the frames and obtain the deformations of the slope model during the

  6. Deriving mechanisms and thresholds for cliff retreat in soft-rock cliffs under changing climates: Rapidly retreating cliffs of the Suffolk coast, UK

    NASA Astrophysics Data System (ADS)

    Brooks, S. M.; Spencer, T.; Boreham, S.

    2012-06-01

    Understanding changing thresholds and mechanisms for retreat in soft rock cliffs is important under changing climates. This can be achieved through combining detailed field observation, long-term process and morphological monitoring and numerical modelling. The cliffs of the Suffolk coast, southern North Sea have exhibited long-term (1883-2010) recession rates of 3.5 m a- 1, rising to 4.7 m a- 1 in the period 1993-2010. Annual to biannual ground survey data, and the application of GIS techniques to digitised records of changing shoreline position from historic maps and aerial photography, reveal considerable decadal-scale variations in cliff recession, within which are nested inter-annual fluctuations in rates of retreat. Archival datasets on significant periods of onshore winds and their interaction with high water levels (including the incidence of storm surges) and rainstorm events are used to determine thresholds for cliff base erosion and its propagation upwards through the cliff profile. In addition, the ‘GEO-Slope' dynamic coupled hydrology-stability model is used to establish thresholds for cliff face failures driven by variations in rainfall inputs. Retreat mechanisms are complex, governed by cliff geology, both as a primary control on suction loss and through its interaction with basal marine conditions. The study allows a general model of cliff retreat for soft rock cliffs to be put forward, whereby a resistant basal platform is overlain by more erodible, weakly and moderately cemented sands and gravels. In this model, the varying balance between marine and terrestrial forcing factors are reflected in low (< 4 m a- 1), intermediate (4-7 m a- 1) and high (> 7 m a- 1) modes of cliff retreat.

  7. National assessment of shoreline change part 4: historical coastal cliff retreat along the California coast

    USGS Publications Warehouse

    Hapke, Cheryl J.; Reid, David

    2007-01-01

    Coastal cliff retreat, the landward migration of the cliff face, is a chronic problem along many rocky coastlines in the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding trends and rates of coastal cliff retreat. There is also a need for a comprehensive analysis of cliff retreat that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey is conducting an analysis of historical coastal cliff retreat along open-ocean rocky coastlines of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard repeatable methods for mapping and analyzing coastal cliff retreat so that periodic updates of coastal erosion can be made nationally that are systematic and internally consistent. This report on the California Coast is an accompaniment to a report on long-term sandy shoreline change for California. This report summarizes the methods of analysis, interprets the results, and provides explanations regarding long-term rates of cliff retreat. Neither detailed background information on the National Assessment of Shoreline Change Project nor detailed descriptions of the geology and geomorphology of the California coastline are presented in this report. The reader is referred to the shoreline change report (Hapke et al., 2006) for this type of background information. Cliff retreat evaluations are based on comparing one historical cliff edge digitized from maps, with a recent cliff edge interpreted from lidar (Light Detection and Ranging) topographic surveys. The historical cliff edges are from a period ranging from 1920-1930, whereas the lidar cliff edges are from either 1998 or 2002. Long-term (~70-year) rates of retreat are calculated using the two cliff edges. The rates of retreat presented in this report represent conditions from the 1930

  8. Gully head retreat rates in the semi-arid highlands of Northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Frankl, Amaury; Poesen, Jean; Deckers, Jozef; Haile, Mitiku; Nyssen, Jan

    2012-11-01

    Due to overgrazing and agricultural intensification, gully erosion severely affects sub-Saharan countries; however, insufficient quantitative studies exist for this part of the world. This paper presents data on gully head retreat rates in Northern Ethiopia and relates these rates to gully and environmental characteristics. The monitoring of headcuts over one rainy season (2010) revealed that present-day retreat rates are low, with average annual linear (Rl), areal (Ra) and volumetric (Ve) retreat rates of 0.34 m y- 1, 1.70 m2 y- 1 and 5.2 m3 y- 1, respectively. These results express the positive effects of recent soil and water conservation practices on gully stabilization. Significantly higher values of Rl (up to 1.93 m y- 1) occurred in the Vertisol areas affected by soil piping. When considering the medium- to long time scale (1-47 years) using archival terrestrial (and aerial) photographs, headcut retreat rates proved to be significantly higher than those in the short term. The averages for Rl, Ra and Ve are 3.8 m y- 1, 31.5 m2 y- 1 and 47.7 m3 y- 1, respectively. Retreat rates are up to 10 times higher after road construction. For the medium to long term, headcut retreat rates were positively related to the catchment area (A). A power relationship that best describes the relation between Ve and A is Ve = 0.53 A0.31 (r2 = 0.27, n = 18). Compared to other areas worldwide, regressive erosion has been rapid in Ethiopia as a result of the degraded and steep landscape combined with erosive rains and the occurrence of Vertisols. In Vertisols, headcut retreat is controlled by soil piping. Because no adequate techniques exist to control gully initiation and development in Vertisols, alternative techniques should be developed that deactivate soil pipes.

  9. Loitering of the retreating sea ice edge in the Arctic Seas

    PubMed Central

    Ermold, Wendy

    2015-01-01

    Abstract Each year, the arctic sea ice edge retreats from its winter maximum extent through the Seasonal Ice Zone (SIZ) to its summer minimum extent. On some days, this retreat happens at a rapid pace, while on other days, parts of the pan‐arctic ice edge hardly move for periods of days up to 1.5 weeks. We term this stationary behavior “ice edge loitering,” and identify areas that are more prone to loitering than others. Generally, about 20–25% of the SIZ area experiences loitering, most often only one time at any one location during the retreat season, but sometimes two or more times. The main mechanism controlling loitering is an interaction between surface winds and warm sea surface temperatures in areas from which the ice has already retreated. When retreat happens early enough to allow atmospheric warming of this open water, winds that force ice floes into this water cause melting. Thus, while individual ice floes are moving, the ice edge as a whole appears to loiter. The time scale of loitering is then naturally tied to the synoptic time scale of wind forcing. Perhaps surprisingly, the area of loitering in the arctic seas has not changed over the past 25 years, even as the SIZ area has grown. This is because rapid ice retreat happens most commonly late in the summer, when atmospheric warming of open water is weak. We speculate that loitering may have profound effects on both physical and biological conditions at the ice edge during the retreat season. PMID:27812435

  10. Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat.

    PubMed

    Pasotti, Francesca; Saravia, Leonardo Ariel; De Troch, Marleen; Tarantelli, Maria Soledad; Sahade, Ricardo; Vanreusel, Ann

    2015-01-01

    The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands), a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis) at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring) species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i) either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii) over time driving the benthic assemblages into a more compact trophic structure with increased

  11. Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat

    PubMed Central

    Pasotti, Francesca; Saravia, Leonardo Ariel; De Troch, Marleen; Tarantelli, Maria Soledad; Sahade, Ricardo; Vanreusel, Ann

    2015-01-01

    The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands), a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis) at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring) species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i) either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii) over time driving the benthic assemblages into a more compact trophic structure with increased

  12. Retreatment of Recurrent Internal Carotid-Posterior Communicating Artery Aneurysm after Coil Embolization.

    PubMed

    Toyota, Shingo; Taki, Takuyu; Wakayama, Akatsuki; Yoshimine, Toshiki

    2015-01-01

    Internal carotid-posterior communicating artery (IC-PC) aneurysms account for more than 20% of all intracranial aneurysms. As a result of the increase in coiling, there has also been an increase in recurrent IC-PC aneurysms after coiling. We present our experience of 10 recurrent IC-PC aneurysms after coiling that were retreated using surgical or endovascular techniques in order to discuss the choice of treatment and the points of clipping without removal of coils. From 2007 to 2014, 10 recurrent IC-PC aneurysms after coiling were retreated. When the previous frames covered the aneurysms all around or almost around except a part of the neck, coiling was chosen. In other cases, clipping was chosen. Clipping was attempted without removal of coils when it was technically feasible. Among the 10 IC-PC aneurysms retreated, 3 were retreated with coiling and 7 were retreated with clipping. In all three cases retreated with coiling, almost complete occlusion was accomplished. In the seven cases retreated with clipping, coil extrusion was observed during surgery in six cases. In most of them, it was necessary to dissect strong adhesions around the coiled aneurysms and to utilize temporary occlusion of the internal carotid artery. In all seven cases, neck clipping was accomplished without the removal of coils. There were no neurological complications in any cases. The management of recurrent lesions of embolized IC-PC aneurysms requires appropriate choice of treatment using both coiling and clipping. Clipping, especially without the removal of coils, plays an important role in safe treatment.

  13. Wastewater retreatment and reuse system for agricultural irrigation in rural villages.

    PubMed

    Kim, Minyoung; Lee, Hyejin; Kim, Minkyeong; Kang, Donghyeon; Kim, Dongeok; Kim, YoungJin; Lee, Sangbong

    2014-01-01

    Climate changes and continuous population growth increase water demands that will not be met by traditional water resources, like surface and ground water. To handle increased water demand, treated municipal wastewater is offered to farmers for agricultural irrigation. This study aimed to enhance the effluent quality from worn-out sewage treatment facilities in rural villages, retreat effluent to meet water quality criteria for irrigation, and assess any health-related and environmental impacts from using retreated wastewater irrigation on crops and in soil. We developed the compact wastewater retreatment and reuse system (WRRS), equipped with filters, ultraviolet light, and bubble elements. A pilot greenhouse experiment was conducted to evaluate lettuce growth patterns and quantify the heavy metal concentration and pathogenic microorganisms on lettuce and in soil after irrigating with tap water, treated wastewater, and WRRS retreated wastewater. The purification performance of each WRRS component was also assessed. The study findings revealed that existing worn-out sewage treatment facilities in rural villages could meet the water quality criteria for treated effluent and also reuse retreated wastewater for crop growth and other miscellaneous agricultural purposes. PMID:25521131

  14. Coupled ice shelf-ocean modeling and complex grounding line retreat from a seabed ridge

    NASA Astrophysics Data System (ADS)

    De Rydt, J.; Gudmundsson, G. H.

    2016-05-01

    Recent observations and modeling work have shown a complex mechanical coupling between Antarctica's floating ice shelves and the adjacent grounded ice sheet. A prime example is Pine Island Glacier, West Antarctica, which has a strong negative mass balance caused by a recent increase in ocean-induced melting of its ice shelf. The mass loss coincides with the retreat of the grounding line from a seabed ridge, on which it was at least partly grounded until the 1970s. At present, it is unclear what has caused the onset of this retreat and how feedback mechanisms between the ocean and ice shelf geometry have influenced the ice dynamics. To address these questions, we present the first results from an offline coupling between a state-of-the-art shallow-ice flow model with grounding line resolving capabilities and a three-dimensional ocean general circulation model with a static implementation of the ice shelf. A series of idealized experiments simulate the retreat from a seabed ridge in response to changes in the ocean forcing, and we show that the retreat becomes irreversible after 20 years of warm ocean conditions. A comparison to experiments with a simple depth-dependent melt rate parameterization demonstrates that such parameterizations are unable to capture the details of the retreat process, and they overestimate mass loss by more than 40% over a 50 year timescale.

  15. Wastewater retreatment and reuse system for agricultural irrigation in rural villages.

    PubMed

    Kim, Minyoung; Lee, Hyejin; Kim, Minkyeong; Kang, Donghyeon; Kim, Dongeok; Kim, YoungJin; Lee, Sangbong

    2014-01-01

    Climate changes and continuous population growth increase water demands that will not be met by traditional water resources, like surface and ground water. To handle increased water demand, treated municipal wastewater is offered to farmers for agricultural irrigation. This study aimed to enhance the effluent quality from worn-out sewage treatment facilities in rural villages, retreat effluent to meet water quality criteria for irrigation, and assess any health-related and environmental impacts from using retreated wastewater irrigation on crops and in soil. We developed the compact wastewater retreatment and reuse system (WRRS), equipped with filters, ultraviolet light, and bubble elements. A pilot greenhouse experiment was conducted to evaluate lettuce growth patterns and quantify the heavy metal concentration and pathogenic microorganisms on lettuce and in soil after irrigating with tap water, treated wastewater, and WRRS retreated wastewater. The purification performance of each WRRS component was also assessed. The study findings revealed that existing worn-out sewage treatment facilities in rural villages could meet the water quality criteria for treated effluent and also reuse retreated wastewater for crop growth and other miscellaneous agricultural purposes.

  16. Coupled ice shelf-ocean modeling and complex grounding line retreat for Pine Island Glacier

    NASA Astrophysics Data System (ADS)

    De Rydt, Jan; Gudmundsson, Hilmar

    2016-04-01

    Recent observations and modeling work have shown a complex mechanical coupling between Antarctica's floating ice shelves and the adjacent grounded ice sheet. A prime example is Pine Island Glacier, West Antarctica, which has a strong negative mass balance caused by a recent increase in ocean-induced melting of its ice shelf. The mass loss coincides with the retreat of the grounding line from a seabed ridge, on which it was at least partly grounded until the 1970s. At present, it is unclear what has caused the onset of this retreat, and how feedback mechanisms between the ocean and iceshelf geometry have influenced the ice dynamics. To address these questions, we present results from an offline coupling between a state-of-the-art shallow-ice flow model with grounding line resolving capabilities, and a three-dimensional ocean general circulation model with a static implementation of the ice shelf. A series of idealized experiments simulate the retreat from a seabed ridge in response to changes in the ocean forcing, and we show that the retreat becomes irreversible after 20 years of warm ocean conditions. A comparison to experiments with a simple depth-dependent meltrate parameterisation demonstrates that such parameterizations are unable to capture the details of the retreat process, and they overestimate mass loss by more than 40% over a 50-year timescale.

  17. Map showing coastal cliff retreat rates along the Big Sur coast, Monterey and San Luis Obispo Counties, California

    USGS Publications Warehouse

    Hapke, Cheryl J.; Green, Krystal R.

    2004-01-01

    The average coastal cliff retreat rate along the Big Sur coast is 18 ? 6 cm/yr as measured over a 52-year time period. The erosion reference features measured as the cliff edge include the well-defined cliff edges common to marine terraces, slight breaks in the slope defining the upper edge of the active lower slope, and the road grade. Cliff erosion and retreat are focused in isolated erosion hotspots that account for most of the calculated average retreat.

  18. Onset and retreat of the Indian monsoon on the southern and northern slopes of the Himalayas as described by precipitation stable isotopes

    NASA Astrophysics Data System (ADS)

    Yu, Wusheng

    2016-04-01

    This project launched the first study to compare the stable isotopes (δ18O and δD) in daily precipitation at the Kathmandu and Tingri stations located on the southern and northern slopes of the central Himalayas, respectivily. Results show that low δ18O and δD values of summer precipitation at the two stations were closely related to intense convection of the Indian monsoon. However, summer δ18O and δD values at Tingri were lower than those at Kathmandu, a result of the lift effect of the Himalayas, coupled with convection disturbances and lower temperatures at Tingri. In winter, the relatively high δ18O and δD values of precipitation at the two stations appears to have resulted from the influence of the westerlies. Compared with those during the summer, the subsidence of the westerlies and northerly winds resulted in relatively high δ18O and δD values of the winter precipitation at Tingri. The δ18O and δD values in winter precipitation at Kathmandu far exceeded those at Tingri, due to more intense advection of the southern branch of the westerlies, and higher temperatures and relative humidity at Kathmandu. The detailed differences in stable isotopes between the two stations follow short-term variability in the onset date of the Indian monsoon and its retreat across the central Himalayas. During the entire sampling period, the Indian monsoon onset at Tingri occurred approximately one week later than that at Kathmandu. However, the retreat at Tingri began roughly three days earlier. Clearly, the duration of the Indian monsoon effects last longer at Kathmandu than that at Tingri. Our findings also indicate that the India monsoon travels slowly northward across the central Himalayas due to the blocking of the Himalayas, but retreats quickly from north to south.

  19. Antarctic last interglacial isotope peak in response to sea ice retreat not ice-sheet collapse.

    PubMed

    Holloway, Max D; Sime, Louise C; Singarayer, Joy S; Tindall, Julia C; Bunch, Pete; Valdes, Paul J

    2016-01-01

    Several studies have suggested that sea-level rise during the last interglacial implies retreat of the West Antarctic Ice Sheet (WAIS). The prevalent hypothesis is that the retreat coincided with the peak Antarctic temperature and stable water isotope values from 128,000 years ago (128 ka); very early in the last interglacial. Here, by analysing climate model simulations of last interglacial WAIS loss featuring water isotopes, we show instead that the isotopic response to WAIS loss is in opposition to the isotopic evidence at 128 ka. Instead, a reduction in winter sea ice area of 65±7% fully explains the 128 ka ice core evidence. Our finding of a marked retreat of the sea ice at 128 ka demonstrates the sensitivity of Antarctic sea ice extent to climate warming. PMID:27526639

  20. Retreatment of patients who do not respond to initial therapy for chronic hepatitis C.

    PubMed

    Shiffman, Mitchell L

    2004-05-01

    Despite improvements in the treatment of chronic hepatitis C virus (HCV) infection, nearly half of all patients do not respond to initial therapy. Retreatment of these patients with pegylated interferon and ribavirin has been successful in only a limited percentage of cases. Factors associated with sustained virologic response (SVR) following retreatment include prior treatment with interferon monotherapy, HCV genotype 2 or 3, a low serum HCV RNA level, and the absence of cirrhosis. Fewer than 6% of nonresponders who were previously treated with interferon and ribavirin and who have cirrhosis, genotype 1, and a high viral load achieve SVR following retreatment with pegylated interferon and ribavirin. No therapy has been shown to yield SVR in patients who do not respond to pegylated interferon and ribavirin. Long-term maintenance therapy with pegylated interferon is currently being evaluated in nonresponders with advanced fibrosis and cirrhosis. Its use should be considered investigational at this time. PMID:15468612

  1. Antarctic last interglacial isotope peak in response to sea ice retreat not ice-sheet collapse

    PubMed Central

    Holloway, Max D.; Sime, Louise C.; Singarayer, Joy S.; Tindall, Julia C.; Bunch, Pete; Valdes, Paul J.

    2016-01-01

    Several studies have suggested that sea-level rise during the last interglacial implies retreat of the West Antarctic Ice Sheet (WAIS). The prevalent hypothesis is that the retreat coincided with the peak Antarctic temperature and stable water isotope values from 128,000 years ago (128 ka); very early in the last interglacial. Here, by analysing climate model simulations of last interglacial WAIS loss featuring water isotopes, we show instead that the isotopic response to WAIS loss is in opposition to the isotopic evidence at 128 ka. Instead, a reduction in winter sea ice area of 65±7% fully explains the 128 ka ice core evidence. Our finding of a marked retreat of the sea ice at 128 ka demonstrates the sensitivity of Antarctic sea ice extent to climate warming. PMID:27526639

  2. Antarctic last interglacial isotope peak in response to sea ice retreat not ice-sheet collapse.

    PubMed

    Holloway, Max D; Sime, Louise C; Singarayer, Joy S; Tindall, Julia C; Bunch, Pete; Valdes, Paul J

    2016-01-01

    Several studies have suggested that sea-level rise during the last interglacial implies retreat of the West Antarctic Ice Sheet (WAIS). The prevalent hypothesis is that the retreat coincided with the peak Antarctic temperature and stable water isotope values from 128,000 years ago (128 ka); very early in the last interglacial. Here, by analysing climate model simulations of last interglacial WAIS loss featuring water isotopes, we show instead that the isotopic response to WAIS loss is in opposition to the isotopic evidence at 128 ka. Instead, a reduction in winter sea ice area of 65±7% fully explains the 128 ka ice core evidence. Our finding of a marked retreat of the sea ice at 128 ka demonstrates the sensitivity of Antarctic sea ice extent to climate warming.

  3. Fast retreat of Zachariæ Isstrøm, northeast Greenland

    NASA Astrophysics Data System (ADS)

    Mouginot, J.; Rignot, E.; Scheuchl, B.; Fenty, I.; Khazendar, A.; Morlighem, M.; Buzzi, A.; Paden, J.

    2015-12-01

    After 8 years of decay of its ice shelf, Zachariæ Isstrøm, a major glacier of northeast Greenland that holds a 0.5-meter sea-level rise equivalent, entered a phase of accelerated retreat in fall 2012. The acceleration rate of its ice velocity tripled, melting of its residual ice shelf and thinning of its grounded portion doubled, and calving is now occurring at its grounding line. Warmer air and ocean temperatures have caused the glacier to detach from a stabilizing sill and retreat rapidly along a downward-sloping, marine-based bed. Its equal-ice-volume neighbor, Nioghalvfjerdsfjorden, is also melting rapidly but retreating slowly along an upward-sloping bed. The destabilization of this marine-based sector will increase sea-level rise from the Greenland Ice Sheet for decades to come.

  4. Rift in Antarctic Glacier: a Unique Chance to Study Ice Shelf Retreat

    NASA Technical Reports Server (NTRS)

    Howat, Ian M.; Jezek, Ken; Studinger, Michael; Macgregor, Joseph A.; Paden, John; Floricioiu, Dana; Russell, Rob; Linkswiler, Matt; Dominguez, Roseanne T.

    2012-01-01

    It happened again, but this time it was caught in the act. During the last week of September 2011 a large transverse rift developed across thefloating terminus of West Antarcticas PineIsland Glacier, less than 5 years after its lastlarge calving event, in 2007 (Figure 1). PineIsland Glaciers retreat has accelerated substantiallyin the past 2 decades, and it is nowlosing 50 gigatons of ice per year, or roughly 25 of Antarcticas total annual contributionto sea level rise [Rignot et al., 2008]. The glaciers recent accelerated retreat is likely triggered by ocean warming and increased submarine melting. As such, it is of significant interest to glaciologists and of heightened societal relevance.

  5. Linking permafrost distribution, glacial retreat and colluvial sediment dynamics in the Saldur River basin, Eastern Italian Alps

    NASA Astrophysics Data System (ADS)

    Brardinoni, Francesco; Sosio, Rosanna; Scotti, Riccardo; Cavalli, Marco; Comiti, Francesco; Mair, Volkmar

    2014-05-01

    In the last three decades generalized atmospheric temperature rise has produced rapid glacial retreat and permafrost degradation in high mountain environments of the European Alps. While it is widely recognized that these changes can impart general instability to mountain slopes (i.e., several projects have documented single case studies of high magnitude-low frequency, catastrophic slope failures), to our knowledge, there appears to be little empirical data available for investigating the spatial distribution of mass-wasting intensity through time in high mountain areas in relation to permafrost degradation and deglaciation patterns. This is a critical shortcoming. Understanding and quantifying the influence of similar transient conditions on mass-wasting processes holds critical long-term implications on the overall sediment flux reshaping mountain landscapes (e.g., post-LGM landscape evolution), as well as more practical short-term applications on water quality issues, damage control/prevention to infrastructure, and reservoir siltation, to mention some. In this contribution we present an integrated approach that aims to: (i) document the spatial distribution of mass-wasting activity and sediment production in the Saldur River basin (97 km^2); (ii) detect causal linkages between mass-wasting intensity, the potential spatial distribution of discontinuous permafrost, and patterns of glacier retreat; and (iii) identify source-to-sink colluvial sedimentary pathways as modulated by the spatial organization of glacial and periglacial landforms. To these ends, we map rock glaciers, protalus ramparts and moraines, and compile a field- and air photo-based multi-temporal (1959-2012) inventory of colluvial sediment sources. We then combine these data with two historical datasets of debris flow and landslide events (both implemented and maintained by the Autonomous Province of Bolzano) and analyse mass-wasting spatial distribution and intensity in relation to proximity of

  6. Joint multiple imputation for longitudinal outcomes and clinical events that truncate longitudinal follow-up.

    PubMed

    Hu, Bo; Li, Liang; Greene, Tom

    2016-07-30

    Longitudinal cohort studies often collect both repeated measurements of longitudinal outcomes and times to clinical events whose occurrence precludes further longitudinal measurements. Although joint modeling of the clinical events and the longitudinal data can be used to provide valid statistical inference for target estimands in certain contexts, the application of joint models in medical literature is currently rather restricted because of the complexity of the joint models and the intensive computation involved. We propose a multiple imputation approach to jointly impute missing data of both the longitudinal and clinical event outcomes. With complete imputed datasets, analysts are then able to use simple and transparent statistical methods and standard statistical software to perform various analyses without dealing with the complications of missing data and joint modeling. We show that the proposed multiple imputation approach is flexible and easy to implement in practice. Numerical results are also provided to demonstrate its performance. Copyright © 2015 John Wiley & Sons, Ltd.

  7. Evolving force balance at Columbia Glacier, Alaska, during its rapid retreat

    USGS Publications Warehouse

    O'Neel, S.; Pfeffer, W.T.; Krimmel, R.; Meier, M.

    2005-01-01

    Changes in driving and resistive stresses play an essential role in governing the buoyancy forces that are important controls on the speed and irreversibility of tidewater glacier retreats. We describe changes in geometry, velocity, and strain rate and present a top-down force balance analysis performed over the lower reach of Columbia Glacier. Our analysis uses new measurements and estimates of basal topography and photogrammetric surface velocity measurements made between 1977 and 2001, while assuming depth-independent strain. Sensitivity tests show that the method is robust and insensitive to small changes in the calculation parameters. Spatial distributions of ice speed show little correspondence with driving stress. Instead, spatial patterns of ice speed exhibit a nonlinear correspondence with basal drag. Primary resistance to flow comes from basal drag, but lateral drag becomes increasingly more important throughout the retreat, which may account for observed increases in speed. Maximum basal drag is always located in a prominent constriction located ~12 km upstream from the preretreat terminus. Once the terminus retreated into deep water off the terminal moraine marking the modern maximum extent, the upstream location of this maximum basal drag helped to promote thinning and decrease effective pressure in the lower region by limiting replenishing ice flow from upstream. An increase in both ice velocity and calving resulted, initiating what appears to be an irreversible retreat. Copyright 2005 by the American Geophysical Union.

  8. Retreating behavior of a charged ionic liquid droplet in a dielectric liquid under electric field

    NASA Astrophysics Data System (ADS)

    Ahn, Myung Mo; Im, Do Jin; Kang, In Seok

    2013-11-01

    Ionic liquids show great promise as excellent solvents or catalysts in energy and biological fields due to their unique chemical and physical properties. The ionic liquid droplets in microfluidic systems can also be used as a potential platform for chemical biological reactions. In order to control electrically the ionic liquid droplets in a microfluidic device, the charging characteristics of ionic liquid droplets need to be understood. In this work, the charging characteristics of various ionic liquids are investigated by using the parallel plate electrodes system. Under normal situation, a charged droplet shows bouncing motion between electrodes continuously. However, for some special ionic liquids, interesting retreating behavior of charged ionic liquid droplet has been observed. This retreating behavior of ionic liquid droplet has been analyzed experimentally by the image analysis and the electrometer signal analysis. Based on the hypothesis of charge leakage of the retreating ionic liquid droplets, FT-IR spectroscopy analysis has also been performed. The retreating behavior of ionic liquid droplet is discussed from the intermolecular point of view according to the species of ionic liquids. This research was supported by grant No. 2013R1A1A2011956 funded by the Ministry of Science, ICT and Future Planning (MSIP) and by grant No. 2013R1A1A2010483 funded by the Ministry of Education, Science and Technology (MEST) through the NRF.

  9. A Century of Retreat at Portage Glacier, South-Central Alaska

    USGS Publications Warehouse

    Kennedy, Ben W.; Trabant, Dennis C.; Mayo, Lawrence R.

    2006-01-01

    Introduction: The Portage Glacier, in south-central Alaska, is viewed by thousands of visitors annually who come to the U.S. Forest Service Begich, Boggs Visitor Center located on the road system between Anchorage and Whittier, Alaska. During the past century, the terminus of the glacier has retreated nearly 5 kilometers to its present location (fig. 1). Like other glaciers that terminate in water, such as Columbia Glacier near Valdez or Mendenhall Glacier near Juneau, Portage Glacier has experienced accelerated retreats in recent decades that likely were initially triggered by climate change begun at the end of the Little Ice Age in the mid-1800s and subsequently controlled in recent history primarily by calving of the glacier terminus. Photographic records of the terminus covering 1914 until present day track the patterns of retreat. These data, coupled with USGS climate information collected from the southern end of the ice field, provide insight to the patterns of retreat that might be observed in the future.

  10. Stepwise tailward retreat of magnetic reconnection: THEMIS observations of an auroral substorm

    NASA Astrophysics Data System (ADS)

    Ieda, A.; Nishimura, Y.; Miyashita, Y.; Angelopoulos, V.; Runov, A.; Nagai, T.; Frey, H. U.; Fairfield, D. H.; Slavin, J. A.; Vanhamäki, H.; Uchino, H.; Fujii, R.; Miyoshi, Y.; Machida, S.

    2016-05-01

    Auroral stepwise poleward expansions were clarified by investigating a multiple-onset substorm that occurred on 27 February 2009. Five successive auroral brightenings were identified in all-sky images, occurring at approximately 10 min intervals. The first brightening was a faint precursor. The second brightening had a wide longitude; thus, it represented the Akasofu substorm onset. Other brightenings expanded poleward; thus, they were interpreted to be auroral breakups. These breakups occurred stepwise; that is, later breakups were initiated at higher latitudes. Corresponding reconnection signatures were studied using Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite observations between 8 and 24 RE down the magnetotail. The Akasofu substorm onset was not accompanied by a clear reconnection signature in the tail. In contrast, the three subsequent auroral breakups occurred simultaneously (within a few minutes) with three successive fast flows at 24 RE; thus, these were interpreted to be associated with impulsive reconnection episodes. These three fast flows consisted of a tailward flow and two subsequent earthward flows. The flow reversal at the second breakup indicated that a tailward retreat of the near-Earth reconnection site occurred during the substorm expansion phase. In addition, the earthward flow at the third breakup was consistent with the classic tailward retreat near the end of the expansion phase; therefore, the tailward retreat is likely to have occurred in a stepwise manner. We interpreted the stepwise characteristics of the tailward retreat and poleward expansion to be potentially associated by a stepwise magnetic flux pileup.

  11. Root canal retreatment using reciprocating and continuous rotary nickel-titanium instruments

    PubMed Central

    de Souza, Patricia Fonseca; Oliveira Goncalves, Leonardo Cantanhede; Franco Marques, Andre Augusto; Sponchiado Junior, Emilio Carlos; Roberti Garcia, Lucas da Fonseca; de Carvalho, Fredson Marcio Acris

    2015-01-01

    Objective: The complete filling material removal during endodontic retreatment is a clinical procedure difficult to achieve. The aim of this study was to evaluate the efficacy of reciprocating and continuous rotary nickel-titanium instruments used in root canal retreatment. Materials and Methods: Forty freshly extracted human premolars were cleaned and shaped by the crown-down technique, followed by filling by the lateral compaction technique. The teeth were randomly separated into two groups (n = 20), according to the system used for filling material removal: G1 - Reciproc and G2 - ProTaper Universal Retreatment System. The teeth were photographed under operating microscope at ×8 magnification; and the total area of the root canal and remaining filling material were quantified. Results: No statistically significant difference (P > 0.05) in residual filling material was observed between groups; however, the time required for filling removal was significantly shorter for Reciproc system (P < 0.05). Conclusions: It was observed remaining filling material in all teeth, irrespective of the system used; however, root canal retreatment was faster when reciprocating motion was used. PMID:26038656

  12. Rapid marine deglaciation: asynchronous retreat dynamics between the Irish Sea Ice Stream and terrestrial outlet glaciers

    NASA Astrophysics Data System (ADS)

    Patton, H.; Hubbard, A.; Bradwell, T.; Glasser, N. F.; Hambrey, M. J.; Clark, C. D.

    2013-08-01

    Understanding the retreat behaviour of past marine-ice sheets provides vital context to accurate assessment of the present stability and long-term response of contemporary polar-ice sheets to climate and oceanic warming. Here new multibeam swath-bathymetry data and sedimentological analysis are combined with high resolution ice-sheet modelling to reveal complex landform assemblages and process-dynamics associated with deglaciation of the British-Celtic Ice Sheet (BCIS) within the Irish Sea Basin. Our reconstruction indicates a non-linear relationship between the rapidly receding Irish Sea Ice Stream, the largest draining the BCIS, and the retreat of outlet glaciers draining the adjacent, terrestrially based ice sheet centred over Wales. Retreat of Welsh ice was episodic; superimposed over low-order oscillations of its margin are asynchronous outlet re-advances driven by catchment-wide mass balance variations that are amplified through migration of the ice cap's main ice-divide. Formation of large, linear ridges which extend at least 12.5 km offshore (locally known as sarns) and dominate the regional bathymetry are attributed to repeated frontal and medial morainic deposition associated with the re-advancing phases of these outlet glaciers. Our study provides new insight into ice-sheet extent, dynamics and non-linear retreat across a major palaeo-ice stream confluence zone, and has ramifications for the interpretation of recent fluctuations observed by satellites over short-time scales across marine-sectors of the Greenland and Antarctic ice sheets.

  13. Rapid marine deglaciation: asynchronous retreat dynamics between the Irish Sea Ice Stream and terrestrial outlet glaciers

    NASA Astrophysics Data System (ADS)

    Patton, H.; Hubbard, A.; Bradwell, T.; Glasser, N. F.; Hambrey, M. J.; Clark, C. D.

    2013-12-01

    Understanding the retreat behaviour of past marine-based ice sheets provides vital context for accurate assessments of the present stability and long-term response of contemporary polar ice sheets to climate and oceanic warming. Here new multibeam swath bathymetry data and sedimentological analysis are combined with high resolution ice-sheet modelling to reveal complex landform assemblages and process dynamics associated with deglaciation of the Celtic ice sheet within the Irish Sea Basin. Our reconstruction indicates a non-linear relationship between the rapidly receding Irish Sea Ice Stream and the retreat of outlet glaciers draining the adjacent, terrestrially based ice cap centred over Wales. Retreat of Welsh ice was episodic; superimposed over low-order oscillations of its margin are asynchronous outlet readvances driven by catchment-wide mass balance variations that are amplified through migration of the ice cap's main ice divide. Formation of large, linear ridges which extend at least 12.5 km offshore (locally known as sarns) and which dominate the regional bathymetry are attributed to repeated frontal and medial morainic deposition associated with the readvancing phases of these outlet glaciers. Our study provides new insight into ice-sheet extent, dynamics and non-linear retreat across a major palaeo-ice stream confluence zone, and has ramifications for the interpretation of recent fluctuations observed by satellites over short timescales across marine sectors of the Greenland and Antarctic ice sheets.

  14. Learning Our Limits: The Science Libraries at Duke University Retreat to Respond To Our Changing Environment.

    ERIC Educational Resources Information Center

    Langley, Anne; Martinez, Linda

    1999-01-01

    Duke University science librarians took a one-day retreat to examine operations, define goals, and explore options for achieving goals. Cost/impact analysis and decision matrix models were used to analyze each librarian's activities. The cost/impact model enabled the librarians to prioritize functions and to better deploy limited resources to…

  15. The Role of Adherence and Retreatment in De Novo Emergence of MDR-TB

    PubMed Central

    Cadosch, Dominique; Abel zur Wiesch, Pia; Kouyos, Roger; Bonhoeffer, Sebastian

    2016-01-01

    Treatment failure after therapy of pulmonary tuberculosis (TB) infections is an important challenge, especially when it coincides with de novo emergence of multi-drug-resistant TB (MDR-TB). We seek to explore possible causes why MDR-TB has been found to occur much more often in patients with a history of previous treatment. We develop a mathematical model of the replication of Mycobacterium tuberculosis within a patient reflecting the compartments of macrophages, granulomas, and open cavities as well as parameterizing the effects of drugs on the pathogen dynamics in these compartments. We use this model to study the influence of patient adherence to therapy and of common retreatment regimens on treatment outcome. As expected, the simulations show that treatment success increases with increasing adherence. However, treatment occasionally fails even under perfect adherence due to interpatient variability in pharmacological parameters. The risk of generating MDR de novo is highest between 40% and 80% adherence. Importantly, our simulations highlight the double-edged effect of retreatment: On the one hand, the recommended retreatment regimen increases the overall success rate compared to re-treating with the initial regimen. On the other hand, it increases the probability to accumulate more resistant genotypes. We conclude that treatment adherence is a key factor for a positive outcome, and that screening for resistant strains is advisable after treatment failure or relapse. PMID:26967493

  16. They're M-e-e-elting!: An Investigation of Glacial Retreat in Antarctica

    ERIC Educational Resources Information Center

    Bugg, Samuel R., IV; Constible, Juanita; Kaput, Marianne; Lee, Richard E., Jr.

    2007-01-01

    In this article, the authors describe the mechanics of They're M-e-e-elting!, an activity wherein middle school students can simulate glacial retreat in Antarctica. They're M-e-e-elting! allows students to melt glaciers, change the water level and salinity of the Southern Ocean, and examine alterations to the Antarctic food web--all without…

  17. Hatchery Effectiveness Technical Work Group Retreat Proceedings, January 9-11, 1990.

    SciTech Connect

    Fickeisen, Duane H.; Neitzel, D.A.; Dauble, Dennis D.

    1990-04-01

    This report summarizes a retreat held for the Hatchery Effectiveness Technical Work Group (HETWG). The objectives were to improve the effectiveness of the Technical Work Group (TWG) through developing procedures for its operation, and to develop an action plan for revision of their current research plan.

  18. Earliest Holocene south Greenland ice sheet retreat within its late Holocene extent

    NASA Astrophysics Data System (ADS)

    Carlson, Anders E.; Winsor, Kelsey; Ullman, David J.; Brook, Edward J.; Rood, Dylan H.; Axford, Yarrow; LeGrande, Allegra N.; Anslow, Faron S.; Sinclair, Gaylen

    2014-08-01

    Early Holocene summer warmth drove dramatic Greenland ice sheet (GIS) retreat. Subsequent insolation-driven cooling caused GIS margin readvance to late Holocene maxima, from which ice margins are now retreating. We use 10Be surface exposure ages from four locations between 69.4°N and 61.2°N to date when in the early Holocene south to west GIS margins retreated to within these late Holocene maximum extents. We find that this occurred at 11.1 ± 0.2 ka to 10.6 ± 0.5 ka in south Greenland, significantly earlier than previous estimates, and 6.8 ± 0.1 ka to 7.9 ± 0.1 ka in southwest to west Greenland, consistent with existing 10Be ages. At least in south Greenland, these 10Be ages likely provide a minimum constraint for when on a multicentury timescale summer temperatures after the last deglaciation warmed above late Holocene temperatures in the early Holocene. Current south Greenland ice margin retreat suggests that south Greenland may have now warmed to or above earliest Holocene summer temperatures.

  19. A chronology for the retreat of the Irish Sea Ice-Stream using Bayesian modelling techniques

    NASA Astrophysics Data System (ADS)

    Thrasher, I. M.; Chiverrell, R. C.; Thomas, G. S. P.; Mauz, B.; Lang, A.

    2009-04-01

    During Marine Isotope Stage (MIS) 2 the Irish Sea Basin was occupied by the Irish Sea Ice-Stream (ISIS), a major outlet for ice which had accumulated in the British and Irish Ice Sheet (BIIS). The flow dynamics and flow phasing of this portion of the BIIS during maximum extent, the Last Glacial Maximum (LGM), and subsequent retreat are poorly understood due to a lack of chronological control. To improve understanding of the timing of maximum ice-stream extent and subsequent retreat, we have compiled the available chronological data for deposits associated with this phase of glaciation. These chronological data were arranged in an expected order using the geomorphological, stratigraphical and sedimentological field evidence. The relative order model broadly comprised a younging sequence from before the advance to LGM limits through subsequent retreat stages. Bayesian modelling techniques were used to evaluate the conformability of this pseudo-stratigraphical relative order model. Lack of conformity in the relative order model either implied problems with individual age determinations or that the relative order of events within the model is flawed, and in both cases the problems required explanation. The relative order model contained 52 age determinations for various phases of ice advance and retreat. Bayesian analysis showed that the relative order model, constructed with information provided by stratigraphical, geomorphological and geographical evidence was conformable with the existing chronology. The incorporation of prior information within the Bayesian framework enabled the refining of probability-based age estimates for the advance and retreat history of the ISIS. The expansion of ISIS to the maximum extent advancing across southern Ireland and into the Celtic Sea appears constrained to between 24.2-22.1 cal. kyr BP. Retreat stage ice-marginal positions are constrained to between 23.9-21.4 cal. kyr BP in Co. Wexford, south-eastern Ireland and between 23

  20. Cytotoxic effect of the debris apically extruded during three different retreatment procedures.

    PubMed

    Silva, Emmanuel J N L; Brito, Mônica E; Ferreira, Vivian D; Belladonna, Felipe G; Neves, Aline A; Senna, Plinio M; De-Deus, Gustavo

    2016-01-01

    We evaluated the cytotoxic effects of the debris apically extruded during root canal retreatment on primary human osteoblast (HOb) cells in vitro. TNF-α and IL-1β levels were also measured. We examined three different techniques: conventional hand-files, and Mtwo and Reciproc retreatments. Filled mandibular incisors were prepared for a cytotoxicity assay in an experimental root model. The material was divided into three groups according to the technique used. Ten teeth were used as control. HOb cells were exposed to the extruded content and cytotoxicity was evaluated using the MTT test (assessing cell metabolic activity). TNF-α and IL-1β production was also analyzed using enzyme-linked immunosorbent assay. Then, all the teeth were radiographed and the residual filling material was quantified. Data were subjected to analysis of variance (ANOVA) and Tukey's test (P < 0.05). The conventional hand-file technique was significantly more cytotoxic than the other methods (P < 0.05). Reciproc was less cytotoxic than Mtwo retreatment (P < 0.05). All endodontic retreatment techniques led to a significant upregulation of IL-1β levels (P < 0.05). However, only the conventional hand-file technique caused a significant increase in TNF-α levels (P < 0.05). Root-filling removal did not affect the levels of these proteins (P > 0.05). The Reciproc system required less time than the other two methods to remove the root-filling materials (P < 0.01). The endodontic retreatment with Reciproc was the least cytotoxic and the least time-consuming method of gutta-percha and sealer removal. (J Oral Sci 58, 211-217, 2016). PMID:27349542

  1. Repeated large-scale retreat and advance of Totten Glacier indicated by inland bed erosion.

    PubMed

    Aitken, A R A; Roberts, J L; van Ommen, T D; Young, D A; Golledge, N R; Greenbaum, J S; Blankenship, D D; Siegert, M J

    2016-05-18

    Climate variations cause ice sheets to retreat and advance, raising or lowering sea level by metres to decametres. The basic relationship is unambiguous, but the timing, magnitude and sources of sea-level change remain unclear; in particular, the contribution of the East Antarctic Ice Sheet (EAIS) is ill defined, restricting our appreciation of potential future change. Several lines of evidence suggest possible collapse of the Totten Glacier into interior basins during past warm periods, most notably the Pliocene epoch, causing several metres of sea-level rise. However, the structure and long-term evolution of the ice sheet in this region have been understood insufficiently to constrain past ice-sheet extents. Here we show that deep ice-sheet erosion-enough to expose basement rocks-has occurred in two regions: the head of the Totten Glacier, within 150 kilometres of today's grounding line; and deep within the Sabrina Subglacial Basin, 350-550 kilometres from this grounding line. Our results, based on ICECAP aerogeophysical data, demarcate the marginal zones of two distinct quasi-stable EAIS configurations, corresponding to the 'modern-scale' ice sheet (with a marginal zone near the present ice-sheet margin) and the retreated ice sheet (with the marginal zone located far inland). The transitional region of 200-250 kilometres in width is less eroded, suggesting shorter-lived exposure to eroding conditions during repeated retreat-advance events, which are probably driven by ocean-forced instabilities. Representative ice-sheet models indicate that the global sea-level increase resulting from retreat in this sector can be up to 0.9 metres in the modern-scale configuration, and exceeds 2 metres in the retreated configuration.

  2. Repeated large-scale retreat and advance of Totten Glacier indicated by inland bed erosion.

    PubMed

    Aitken, A R A; Roberts, J L; van Ommen, T D; Young, D A; Golledge, N R; Greenbaum, J S; Blankenship, D D; Siegert, M J

    2016-05-19

    Climate variations cause ice sheets to retreat and advance, raising or lowering sea level by metres to decametres. The basic relationship is unambiguous, but the timing, magnitude and sources of sea-level change remain unclear; in particular, the contribution of the East Antarctic Ice Sheet (EAIS) is ill defined, restricting our appreciation of potential future change. Several lines of evidence suggest possible collapse of the Totten Glacier into interior basins during past warm periods, most notably the Pliocene epoch, causing several metres of sea-level rise. However, the structure and long-term evolution of the ice sheet in this region have been understood insufficiently to constrain past ice-sheet extents. Here we show that deep ice-sheet erosion-enough to expose basement rocks-has occurred in two regions: the head of the Totten Glacier, within 150 kilometres of today's grounding line; and deep within the Sabrina Subglacial Basin, 350-550 kilometres from this grounding line. Our results, based on ICECAP aerogeophysical data, demarcate the marginal zones of two distinct quasi-stable EAIS configurations, corresponding to the 'modern-scale' ice sheet (with a marginal zone near the present ice-sheet margin) and the retreated ice sheet (with the marginal zone located far inland). The transitional region of 200-250 kilometres in width is less eroded, suggesting shorter-lived exposure to eroding conditions during repeated retreat-advance events, which are probably driven by ocean-forced instabilities. Representative ice-sheet models indicate that the global sea-level increase resulting from retreat in this sector can be up to 0.9 metres in the modern-scale configuration, and exceeds 2 metres in the retreated configuration. PMID:27193684

  3. Diachronous seawater retreat from the southwestern margin of the Tarim Basin in the late Eocene

    NASA Astrophysics Data System (ADS)

    Sun, Jimin; Windley, Brian F.; Zhang, Zhiliang; Fu, Bihong; Li, Shihu

    2016-02-01

    In contrast to the present hyper-arid inland basin surrounded by the high mountains of Central Asia, the western Tarim Basin was once connected with the Tajik Basin at least in the late Eocene, when an epicontinental sea extended from the western Tarim Basin to Europe. Western Tarim is a key site for studying the retreat of seawater, which was likely caused by the northward indentation of the Pamir arc and facilitated by the climatic cooling and eustatic sea level change in the Cenozoic. Here we present a new magnetostratigraphic record from the Tarim Basin that provides evidence of diachronous seawater retreat from its southwestern margin. We studied about 1360 m of well-exposed Eocene-Oligocene strata at Keliyang in the folded foreland of the West Kunlun orogen. Until now, the age of the strata has only been minimally constrained by the presence of late mid-Eocene marine fossils. Our biostratigraphic and magnetostratigraphic results demonstrate that the age of the sedimentary sequence ranges from ∼46 Ma to ∼26 Ma (mid-Eocene to late-Oligocene) and the seawater retreat at Keliyang took place at ∼40 Ma. Considering the stepwise northward indentation and uplift of the Pamir orogen, together with the other previous results, we propose that seawater retreat from the southwestern margin of the Tarim Basin was diachronous in the late Eocene ranging from 47 Ma to 40 Ma. The regional indentation, uplift and erosion of the Pamir orogen played the dominant and important role in controlling the seawater retreat from the southwestern margin of the Tarim Basin.

  4. Repeated large-scale retreat and advance of Totten Glacier indicated by inland bed erosion

    NASA Astrophysics Data System (ADS)

    Aitken, A. R. A.; Roberts, J. L.; Ommen, T. D. Van; Young, D. A.; Golledge, N. R.; Greenbaum, J. S.; Blankenship, D. D.; Siegert, M. J.

    2016-05-01

    Climate variations cause ice sheets to retreat and advance, raising or lowering sea level by metres to decametres. The basic relationship is unambiguous, but the timing, magnitude and sources of sea-level change remain unclear; in particular, the contribution of the East Antarctic Ice Sheet (EAIS) is ill defined, restricting our appreciation of potential future change. Several lines of evidence suggest possible collapse of the Totten Glacier into interior basins during past warm periods, most notably the Pliocene epoch, causing several metres of sea-level rise. However, the structure and long-term evolution of the ice sheet in this region have been understood insufficiently to constrain past ice-sheet extents. Here we show that deep ice-sheet erosion—enough to expose basement rocks—has occurred in two regions: the head of the Totten Glacier, within 150 kilometres of today’s grounding line; and deep within the Sabrina Subglacial Basin, 350-550 kilometres from this grounding line. Our results, based on ICECAP aerogeophysical data, demarcate the marginal zones of two distinct quasi-stable EAIS configurations, corresponding to the ‘modern-scale’ ice sheet (with a marginal zone near the present ice-sheet margin) and the retreated ice sheet (with the marginal zone located far inland). The transitional region of 200-250 kilometres in width is less eroded, suggesting shorter-lived exposure to eroding conditions during repeated retreat-advance events, which are probably driven by ocean-forced instabilities. Representative ice-sheet models indicate that the global sea-level increase resulting from retreat in this sector can be up to 0.9 metres in the modern-scale configuration, and exceeds 2 metres in the retreated configuration.

  5. Re-treatment of patients with hepatitis C who failed to respond (nonresponders) to previous treatment.

    PubMed

    Sharvadze, L G; Gogichaishvili, Sh Sh; Sakandelidze, Ts G; Zhamutashvili, M T; Chkhartishvili, N I

    2009-01-01

    The aim of four-year follow up study was evaluation of re-treatment efficacy of antiviral therapy in patients with hepatitis C who failed to respond (non responders) to previous therapy. Study enrolled 29 patients, aged 21-59 with HCV infection (15 had HCV genotype 1, and 14 had HCV non-genotype1), who previously were treated with unmodified interferon alfa (conventional interferon) 2a or 2b 5 MIU TIW plus ribavirin (1000-1200 mg/day) and who failed under this therapy. Study subjects were randomized into two groups: in group I were included 17 patients--relapsers (patient in whom HCV RNA becomes undetectable on treatment and is undetectable at the end of therapy, but is detected again after discontinuation of treatment). Group II was composed of 12 patients: 4 were non responders (patient in whom HCV RNA levels remain stable on treatment), 4--partial responders (HCV RNA levels decline by >2 logs, but never become undetectable during treatment) and 4--breakthrough non responders (HCV RNA become undetectable during treatment, but before-treatment termination again become detectable). The diagnosis of HCV infection was made based on detection of HCV antibodies by ELISA and confirmed by RIBA. Detection of HCV RNA (qualitative) and HCV RNA Viral load--by Real time PCR technique (COBAS TaqMan Test). HCV genotypes were detected by INNO-Lipa method. In group I--rapid virological response (RVR) was observed in 10 (58%) patients, early viral response (EVR) in 12 patients (70%). Among them 9 (52%) patients remained HCV RNA undetectable by the end of treatment. After 6 months sustained viral response (SVR) was received in 7 (41%) patients from group I. In group II--RVR was observed in 5 (41%), EVR in 6 (50%) patients. Among them 5 (41%) patients remained HCV RNA undetectable by the end of treatment. After 6 months Sustained Viral Response was received in 3 (25%) patients. Re-treatment with pegylated interferon and ribavirin in patients with hepatitis C who failed to responds

  6. Ice stream retreat following the LGM and onset of the west Greenland current in Uummannaq Trough, west Greenland

    NASA Astrophysics Data System (ADS)

    Sheldon, Christina; Jennings, Anne; Andrews, John T.; Ó Cofaigh, Colm; Hogan, Kelly; Dowdeswell, Julian A.; Seidenkrantz, Marit-Solveig

    2016-09-01

    The deglacial history and oceanography of Uummannaq Trough, central West Greenland continental shelf, was investigated using foraminiferal, sedimentological, and bathymetric records together with a radiocarbon chronology, providing a timeline for the retreat of glacial ice after the Last Glacial Maximum (LGM). To map ice stream retreat, data were collected from cores from the outer (JR175-VC45 and JR175-VC43) and inner (JR175-VC42) Uummannaq Trough. A large ice stream, fed by confluent glaciers draining the interior of the Greenland Ice Sheet, extended across the outer shelf during the LGM and was in retreat by 15.0 cal kyr BP. Foraminiferal data indicate that the 'warm' West Greenland Current (WGC) was established prior to 14.0 cal kyr BP, which is the hitherto earliest record of Atlantic Water found on the West Greenland shelf. For each of the cores, foraminifera indicate that ice sheet retreat was followed quickly by incursion of the WGC, suggesting that the warm water may have enhanced ice retreat. Prior to the Younger Dryas cold event, the radiocarbon chronology indicates that the ice sheet retreated to the mid-shelf, where it subsequently stabilised and formed a large grounding-zone wedge (GZW). After the Younger Dryas, around 11.5 cal kyr BP, the ice retreated rapidly from the GZW and into the fjords.

  7. Habitat selection in a rocky landscape: experimentally decoupling the influence of retreat site attributes from that of landscape features.

    PubMed

    Croak, Benjamin M; Pike, David A; Webb, Jonathan K; Shine, Richard

    2012-01-01

    Organisms selecting retreat sites may evaluate not only the quality of the specific shelter, but also the proximity of that site to resources in the surrounding area. Distinguishing between habitat selection at these two spatial scales is complicated by co-variation among microhabitat factors (i.e., the attributes of individual retreat sites often correlate with their proximity to landscape features). Disentangling this co-variation may facilitate the restoration or conservation of threatened systems. To experimentally examine the role of landscape attributes in determining retreat-site quality for saxicolous ectotherms, we deployed 198 identical artificial rocks in open (sun-exposed) sites on sandstone outcrops in southeastern Australia, and recorded faunal usage of those retreat sites over the next 29 months. Several landscape-scale attributes were associated with occupancy of experimental rocks, but different features were important for different species. For example, endangered broad-headed snakes (Hoplocephalus bungaroides) preferred retreat sites close to cliff edges, flat rock spiders (Hemicloea major) preferred small outcrops, and velvet geckos (Oedura lesueurii) preferred rocks close to the cliff edge with higher-than-average sun exposure. Standardized retreat sites can provide robust experimental data on the effects of landscape-scale attributes on retreat site selection, revealing interspecific divergences among sympatric taxa that use similar habitats.

  8. Habitat Selection in a Rocky Landscape: Experimentally Decoupling the Influence of Retreat Site Attributes from That of Landscape Features

    PubMed Central

    Croak, Benjamin M.; Pike, David A.; Webb, Jonathan K.; Shine, Richard

    2012-01-01

    Organisms selecting retreat sites may evaluate not only the quality of the specific shelter, but also the proximity of that site to resources in the surrounding area. Distinguishing between habitat selection at these two spatial scales is complicated by co-variation among microhabitat factors (i.e., the attributes of individual retreat sites often correlate with their proximity to landscape features). Disentangling this co-variation may facilitate the restoration or conservation of threatened systems. To experimentally examine the role of landscape attributes in determining retreat-site quality for saxicolous ectotherms, we deployed 198 identical artificial rocks in open (sun-exposed) sites on sandstone outcrops in southeastern Australia, and recorded faunal usage of those retreat sites over the next 29 months. Several landscape-scale attributes were associated with occupancy of experimental rocks, but different features were important for different species. For example, endangered broad-headed snakes (Hoplocephalus bungaroides) preferred retreat sites close to cliff edges, flat rock spiders (Hemicloea major) preferred small outcrops, and velvet geckos (Oedura lesueurii) preferred rocks close to the cliff edge with higher-than-average sun exposure. Standardized retreat sites can provide robust experimental data on the effects of landscape-scale attributes on retreat site selection, revealing interspecific divergences among sympatric taxa that use similar habitats. PMID:22701592

  9. Longitudinal impedance of RHIC

    SciTech Connect

    Blaskiewicz, M.; Brennan, J. M.; Mernick, K.

    2015-05-03

    The longitudinal impedance of the two RHIC rings has been measured using the effect of potential well distortion on longitudinal Schottky measurements. For the blue RHIC ring Im(Z/n) = 1.5±0.2Ω. For the yellow ring Im(Z/n) = 5.4±1Ω.

  10. Longitudinal Multistage Testing

    ERIC Educational Resources Information Center

    Pohl, Steffi

    2013-01-01

    This article introduces longitudinal multistage testing (lMST), a special form of multistage testing (MST), as a method for adaptive testing in longitudinal large-scale studies. In lMST designs, test forms of different difficulty levels are used, whereas the values on a pretest determine the routing to these test forms. Since lMST allows for…

  11. Identifying potential seasonal and historical drivers of marine-terminating glacier retreat in Disko and Uummannaq Bays, West Greenland

    NASA Astrophysics Data System (ADS)

    York, A.; Frey, K. E.; Das, S. B.

    2015-12-01

    The variability in outlet glacier termini positions is an important indicator of overall glacier health and the net effects of ice-ocean-atmosphere interactions. Glacier margins fluctuate on both seasonal and interannual time scales and satellite imagery provides a critical spatially- and temporally-extensive resource for monitoring glacier behavior. Outlet glaciers have generally been retreating globally over recent decades, but the magnitude of seasonal variation, overall retreat, and foremost drivers have proven unique to each glacier. The outlet glaciers in central West Greenland are generally experiencing the same regional atmospheric forcing, yet previous studies have shown varying magnitudes of retreat over the last forty years. In this study, we utilize Landsat imagery between the years 1985 and 2014 to digitize a time series of glacier front positions of 18 marine-terminating outlet glaciers in the Disko and Uummannaq Bay regions of West Greenland. We examine potential drivers of trends in outlet glacier retreat through satellite observations of adjacent sea ice concentrations and sea surface temperatures. Additionally, reanalysis data and long-term automatic weather station measurements are investigated to contextualize the role of atmospheric drivers at both a regional and local scale. Results indicate retreat of all glaciers in the region over the study period and no indication of a south to north trend in magnitude of retreat on either a seasonal or long-term scale. The 11 glaciers in Uummannaq Bay retreated between 25 m and 3.5 km, an average of 1.22 ± 1.20 km over the entire study period. The retreat of 7 glaciers in Disko Bay ranged from 181 m to 2.3 km, an average of 1.0 ± 0.78 km over the period. Although the mean terminus retreat rate between the two bays is comparable, there remains a wide range of total retreat amounts among the glaciers. We investigate the degree of seasonal variation in terminus position as an indicator of longer

  12. Re-treatment of relapsed Paget's disease of bone with zoledronic acid: results from an open-label study.

    PubMed

    Reid, Ian R; Brown, Jacques P; Levitt, Naomi; Román Ivorra, José A; Bachiller-Corral, Javier; Ross, Ian L; Su, Guoqin; Antunez-Flores, Oscar; Aftring, R Paul

    2013-01-01

    Six patients from the phase 3 trials of zoledronic acid in Paget's disease, who had received zoledronic acid initially and had subsequently relapsed, were entered into an open re-treatment study. Following re-treatment, each patient reached similar absolute nadirs of serum alkaline phosphatase to those recorded after their first dose. No significant adverse events were reported. It is concluded that, while re-treatment of Paget's disease with zoledronic acid is rarely needed, it is safe and effective, with no evidence of treatment resistance based on this small cohort. PMID:24422139

  13. Endodontic Retreatment of a Mandibular Second Molar with four Separate Roots: A Case Report

    PubMed Central

    Idris, Mohamed; Sakkir, Nasil; KJ, Nandakishore; Kini, Annapurna

    2014-01-01

    Aberrations in the root canal anatomy are a commonly occurring phenomenon. Although the mandibular second molar is commonly a bi-rooted tooth with an uncomplicated endodontic anatomy, variations have to be considered every time endodontic therapy is performed. This case report describes the non-surgical endodontic retreatment performed on a mandibular second molar with four seperate roots and canals. ProTaper Universal rotary nickel-titanium instruments (Dentsply Maillefer, Ballaigues, Switzerland) for treatment and retreatment were used to remove the old gutta percha and to clean and shape all root canals, followed by the complete obturation of root canal system. Post-operative CBCT scan was taken to confirm the quality of the performed treatment. PMID:24783160

  14. Surgical Retreatment of an Invaginated Maxillary Central Incisor Following Overfilled Endodontic Treatment: A Case Report

    PubMed Central

    Ozbas, Hakan; Subay, Rustem Kemal; Ordulu, Melike

    2010-01-01

    This case report presents the periapical surgical retreatment of an Oehlers Class III invaginated maxillary central incisor with extruded root canal filling into the periapical lesion. After local anesthesia, a full-thickness mucoperiosteal flap was reflected, and the granulomatous tissue and extruded gutta-percha points were curetted carefully. A deep and wide root-end cavity was prepared and filled with mineral trioxide aggregate (MTA). At 6 months and 2 years after the treatment, the tooth exhibited no clinical symptoms, and the radiograph performed during the 2-year follow-up showed a complete periapical healing around the root end. The present report indicates that MTA retrofilling can be used successfully in the surgical retreatment of dens invaginatus type III cases in which the invagination exits apically. PMID:20613922

  15. Partial embolization as re-treatment of hypersplenism after unsuccessful splenic artery ligation

    PubMed Central

    Xu, Zheng-Ju; Zheng, Lian-Qiu; Pan, Xing-Nan

    2015-01-01

    Ligation of splenic artery (LSA) is used for the treatment of liver cirrhosis with hypersplenism. However, hypersplenism is not significantly improved following LSA treatment in some cases, and there are few reports of retreatment of hypersplenism after LSA. We report the case of a 47-year-old man with liver cirrhosis and hypersplenism who underwent LSA treatment, but did not significantly improve. Laboratory tests revealed severe leukocytopenia and thrombocytopenia. Celiac computed tomography arteriogram and digital subtraction angiography revealed two compensatory arteries connected to the hilar splenic artery from the left gastro-epiploic artery and from the dorsal pancreatic artery. Partial splenic embolization (PSE) was performed through the compensatory arteries. As a result, the patient achieved partial splenic ischemic infarction, and white blood cell and platelet counts rose and remained in the normal range. PSE is an effective therapeutic modality for the retreatment of hypersplenism when other modalities have failed. PMID:25632215

  16. A Case of Successful Retreatment of a Maxillary Lateral Incisor with a Supernumerary Root

    PubMed Central

    Aminsobhani, Mohsen

    2015-01-01

    Knowledge about the morphology of the root canal system is a pre-requisite for achieving a successful outcome in root canal treatment. In this report, a patient with a maxillary lateral incisor which had previously undergone orthograde endodontic retreatment for two times is discussed. The tooth had been misdiagnosed with a palatal groove or a root fracture, its prognosis had been determined to be poor and extraction was advised by a practitioner. During our evaluation, an unrecognized supernumerary root and root canal were detected and the tooth was maintained successfully with orthograde endodontic retreatment. The use of cone beam computed tomography (CBCT) and magnification were of significance in the treatment process of this case. PMID:27252762

  17. Larval caddis-fly nets and retreats: a unique biosedimentary paleocurrent indicator for fossil tufa deposits

    NASA Astrophysics Data System (ADS)

    Drysdale, Russell N.; Carthew, Karen D.; Taylor, Mark P.

    2003-10-01

    Caddis-fly larvae (Order: Trichoptera; Family: Hydropsychidae; Genus: Cheumatopsyche) build distinctive nets and retreats on the surface of tufa deposits in spring-fed rivers of the Barkly karst, northern Australia. Their activities are confined specifically to swiftly flowing reaches, where the nets and retreats form linear arrays arranged almost perpendicular to stream flow. The arrays become encrusted by calcium carbonate and, when high-velocity conditions are maintained, are succeeded by the next generation of caddis flies. The arrays are well preserved in many fossil tufa deposits, where their alignment and long-section morphology indicate paleoflow direction at the time of caddis activity. This can assist in the paleoenvironmental reconstruction of fossil tufa sequences.

  18. Glacial Retreat and Associated Glacial Lake Hazards in the High Tien Shan

    NASA Astrophysics Data System (ADS)

    Smith, T. T.

    2013-12-01

    A number of studies have identified glacial retreat throughout the greater Himalayan region over the past few decades, but the Karakorum region remains an anomaly with large stagnating or advancing glaciers. The glacial behavior in the Tien Shan is still unclear, as few studies have investigated mass balances in the region. This study focuses on the highest peaks of the Tien Shan mountain range, in the region of Jengish Chokusu along the Kyrgyzstan-China-Kazakhstan border. In a first step, a 30-year time series of Landsat imagery (n=27) and ASTER imagery (n=10) was developed to track glacial growth and retreat in the region. Using a combination of spectral and topographic information, glacial outlines are automatically delineated. As several important glaciers in the study region contain medium to high levels of debris cover, our algorithm also improves upon current methods of detecting debris-covered glaciers by using topography, distance weighting methods, river networks, and additional spectral data. Linked to glacial retreat are glacial lake outburst floods (GLOFs) that have become increasingly common in High Mountain Asia over the last few decades. As glaciers retreat, their melt water is often trapped by weakly bonded moraines. These moraines have been known to fail due to overtopping caused by surge waves created by avalanches, rockslides, or glacial calving. A suite of studies throughout High Mountain Asia have used remotely-sensed data to monitor the formation and growth of glacial lakes. In a second step of the work, lake-area changes over the past 15 years were tracked monthly and seasonally using dense Landsat/ASTER coverage (n=30) with an automatic procedure based on spectral and topographic information. Previous work has identified GLOFs as a significant process for infrastructural damage in the southern Tien Shan/northern Pamir, as well as in the better studied Himalaya region. Lake identification and quantification of lake-growth rates is a valuable

  19. Retreatment of recurrent carcinoma of the head and neck by afterloading interstitial 192Ir implant

    SciTech Connect

    Emami, B.; Marks, J.E.

    1983-10-01

    From January 1975 to December 1980, 25 patients with persistent or recurrent carcinomas of the head and neck were retreated for palliation at the Division of Radiation Oncology, Mallinckrodt Institute of Radiology. These patients had all undergone extensive previous treatment by surgery and/or radiation. All were retreated with 192Ir interstitial implant with or without external radiation and/or surgical excision. Of 25 patients, 13 had complete response (CR) and 6 had partial response for a follow-up period of 1 to 7 years. Of 13 patients with CR, 6 are alive with no evidence of disease (NED) and two died NED. Detailed results are presented and the new strategy for such patients is discussed.

  20. Irregular tropical glacier retreat over the Holocene epoch driven by progressive warming.

    PubMed

    Jomelli, Vincent; Khodri, Myriam; Favier, Vincent; Brunstein, Daniel; Ledru, Marie-Pierre; Wagnon, Patrick; Blard, Pierre-Henri; Sicart, Jean-Emmanuel; Braucher, Régis; Grancher, Delphine; Bourlès, Didier Louis; Braconnot, Pascale; Vuille, Mathias

    2011-06-08

    The causes and timing of tropical glacier fluctuations during the Holocene epoch (10,000 years ago to present) are poorly understood. Yet constraining their sensitivity to changes in climate is important, as these glaciers are both sensitive indicators of climate change and serve as water reservoirs for highland regions. Studies have so far documented extra-tropical glacier fluctuations, but in the tropics, glacier-climate relationships are insufficiently understood. Here we present a (10)Be chronology for the past 11,000 years (11 kyr), using 57 moraines from the Bolivian Telata glacier (in the Cordillera Real mountain range). This chronology indicates that Telata glacier retreated irregularly. A rapid and strong melting from the maximum extent occurred from 10.8 ± 0.9 to 8.5 ± 0.4 kyr ago, followed by a slower retreat until the Little Ice Age, about 200 years ago. A dramatic increase in the rate of retreat occurred over the twentieth century. A glacier-climate model indicates that, relative to modern climate, annual mean temperature for the Telata glacier region was -3.3 ± 0.8 °C cooler at 11 kyr ago and remained -2.1 ± 0.8 °C cooler until the end of the Little Ice Age. We suggest that long-term warming of the eastern tropical Pacific and increased atmospheric temperature in response to enhanced austral summer insolation were the main drivers for the long-term Holocene retreat of glaciers in the southern tropics.

  1. Past ice-sheet behaviour: retreat scenarios and changing controls in the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Halberstadt, Anna Ruth W.; Simkins, Lauren M.; Greenwood, Sarah L.; Anderson, John B.

    2016-05-01

    Studying the history of ice-sheet behaviour in the Ross Sea, Antarctica's largest drainage basin can improve our understanding of patterns and controls on marine-based ice-sheet dynamics and provide constraints for numerical ice-sheet models. Newly collected high-resolution multibeam bathymetry data, combined with two decades of legacy multibeam and seismic data, are used to map glacial landforms and reconstruct palaeo ice-sheet drainage. During the Last Glacial Maximum, grounded ice reached the continental shelf edge in the eastern but not western Ross Sea. Recessional geomorphic features in the western Ross Sea indicate virtually continuous back-stepping of the ice-sheet grounding line. In the eastern Ross Sea, well-preserved linear features and a lack of small-scale recessional landforms signify rapid lift-off of grounded ice from the bed. Physiography exerted a first-order control on regional ice behaviour, while sea floor geology played an important subsidiary role. Previously published deglacial scenarios for Ross Sea are based on low-spatial-resolution marine data or terrestrial observations; however, this study uses high-resolution basin-wide geomorphology to constrain grounding-line retreat on the continental shelf. Our analysis of retreat patterns suggests that (1) retreat from the western Ross Sea was complex due to strong physiographic controls on ice-sheet drainage; (2) retreat was asynchronous across the Ross Sea and between troughs; (3) the eastern Ross Sea largely deglaciated prior to the western Ross Sea following the formation of a large grounding-line embayment over Whales Deep; and (4) our glacial geomorphic reconstruction converges with recent numerical models that call for significant and complex East Antarctic ice sheet and West Antarctic ice sheet contributions to the ice flow in the Ross Sea.

  2. A complex deglacial retreat history of the Anvers Island Trough paleo-ice stream

    NASA Astrophysics Data System (ADS)

    Shevenell, A.; Ishman, S. E.; Domack, E. W.; Leventer, A.; Rosenheim, B. E.; Vadman, K. J.

    2015-12-01

    Marine-terminating ice regulates the mass balance and stability of Antarctica's ice sheets and, ultimately, global sea level. However, predictions of future ice sheet response to climate change are limited by short observational time-series and the complexity of associated forcings and feedbacks. Here, we present new chronologic and multiproxy data from 7 marine sediment records from the outer to inner shelf down the axis of the Anvers Island Trough and into Palmer Deep that better constrain the timing and rate of ice retreat and improve understanding of the mechanisms driving deglaciation of this hypothesized paleo-ice stream. The retreat chronology is based on 16 CaCO3 (foraminifer and mollusk) and 45 ramped pyrolysis (acid-insoluble organic matter) AMS 14C dates. Radiocarbon dates from the laminated diatom ooze and mud facies immediately above the glacial diamicton indicate that deglaciation of the mid-Anvers Island Trough post-dated the Palmer Deep deglaciation by ~2000 uncorrected 14C years and that collapse of the mid-shelf system was rapid, if not instantaneous. The laminated facies, present throughout the suite of cores, is consistent with the calving bay reentrant model for deglaciation. However, this facies is limited (~15 couplets) on the mid-shelf and expanded (~127 couplets) on the inner-shelf, suggesting regional differences in calving bay duration. Planktic and benthic foraminifer isotopes, together with foraminifer and diatom assemblages, and biogeochemical data provide evidence for the presence of warmer nutrient-rich modified Circumpolar Deep Water throughout the Anvers Island Trough during deglaciation. The observed retreat complexity may relate to a hypothesized mid-shelf ice-dome system and requires additional geological and geophysical data to understand ice retreat patterns south and west of Palmer Deep. Such data will provide important new constraints for ice sheet models.

  3. Processes controlling the retreat of the Isles Dernieres, a Louisiana barrier-island chain

    USGS Publications Warehouse

    Dingler, John R.; Reiss, Thomas E.

    1991-01-01

    The Isles Dernieres is a low-lying, transgressive barrier-island chain situated about 150 km west of the modern Mississippi delta. Much of the Isles Dernieres consists of highly dissected salt-marsh muds that lie at or slightly above sea level and are covered by a veneer of sand along the shoreline facing the Gulf of Mexico. Maximum berm elevations are generally less than 1.5 m above mean sea level. Since the mid-1800s, the initial island has been fragmented into four islands, and the beach face has retreated landward at a rate of more than 10 m/yr. The dominant processes controlling degradation of the chain are cold fronts that pass through the area several times each year and occasional hurricanes. Beach surveys over a 2-year period on the Isles Dernieres document irreversible beach-face retreat in conjunction with multiple cold fronts and one major hurricane (Gilbert). Although both the hurricane and the cold fronts caused the island to erode, the erosional patterns of the two storm types differed from each other. During the two years, over 60 cold fronts collectively caused about 37 m of beach-face retreat, whereas Gilbert itself produced more than 40 m of retreat. A major difference between the two storm types was in the percentage of washover sand produced by each. Commonly, the cold fronts did not create enough of a storm surge to overtop the berm, so most of the material removed from the beach face must have moved offshore or alongshore. Gilbert, in contrast, inundated the study site, and essentially all the sand removed from the beach face moved to the backshore.

  4. Irregular tropical glacier retreat over the Holocene epoch driven by progressive warming.

    PubMed

    Jomelli, Vincent; Khodri, Myriam; Favier, Vincent; Brunstein, Daniel; Ledru, Marie-Pierre; Wagnon, Patrick; Blard, Pierre-Henri; Sicart, Jean-Emmanuel; Braucher, Régis; Grancher, Delphine; Bourlès, Didier Louis; Braconnot, Pascale; Vuille, Mathias

    2011-06-01

    The causes and timing of tropical glacier fluctuations during the Holocene epoch (10,000 years ago to present) are poorly understood. Yet constraining their sensitivity to changes in climate is important, as these glaciers are both sensitive indicators of climate change and serve as water reservoirs for highland regions. Studies have so far documented extra-tropical glacier fluctuations, but in the tropics, glacier-climate relationships are insufficiently understood. Here we present a (10)Be chronology for the past 11,000 years (11 kyr), using 57 moraines from the Bolivian Telata glacier (in the Cordillera Real mountain range). This chronology indicates that Telata glacier retreated irregularly. A rapid and strong melting from the maximum extent occurred from 10.8 ± 0.9 to 8.5 ± 0.4 kyr ago, followed by a slower retreat until the Little Ice Age, about 200 years ago. A dramatic increase in the rate of retreat occurred over the twentieth century. A glacier-climate model indicates that, relative to modern climate, annual mean temperature for the Telata glacier region was -3.3 ± 0.8 °C cooler at 11 kyr ago and remained -2.1 ± 0.8 °C cooler until the end of the Little Ice Age. We suggest that long-term warming of the eastern tropical Pacific and increased atmospheric temperature in response to enhanced austral summer insolation were the main drivers for the long-term Holocene retreat of glaciers in the southern tropics. PMID:21654802

  5. On optimal retreat distance for the equivalent source method-based nearfield acoustical holography.

    PubMed

    Bai, Mingsian R; Chen, Ching-Cheng; Lin, Jia-Hong

    2011-03-01

    As a basic form of the equivalent source method (ESM) that is used to nearfield acoustical holography (NAH) problems, discrete monopoles are utilized to represent the sound field of interest. When setting up the virtual source distribution, it is vital to maintain a "retreat distance" between the virtual sources and the actual source surface such that reconstruction would not suffer from singularity problems. However, one cannot increase the distance without bound because of the ill-posedness inherent in the reconstruction process with large distance. In prior research, 1-2 times lattice spacing, or the inter-element distance of microphones, is generally recommended as retreat distance in using the ESM-based NAH. While this rule has shown to yield good results in many cases, the optimal choice is a complicated issue that depends on frequency, geometry of the physical source, content of evanescent waves, distribution of sensors and virtual sources, etc. This paper deals about attaining the best compromise between the reconstruction errors induced by the point source singularity; the reconstruction ill-posedness is an interesting problem in its own right. The paper revisits this issue, with the aid of an optimization algorithm based on the golden section search and parabolic interpolation. Numerical simulations were conducted for a baffled planar piston source and a spherically baffled piston source. The results revealed that the retreat distance appropriate for the ESM ranged from 0.4 to 0.5 times the spacing for the planar piston, while from 0.8 to 1.7 times average spacing for the spherical piston. Experiments carried out for a vibrating aluminum plate also revealed that the retreat distance with 0.5 times the spacing yielded better reconstructed velocity than those with 1/20 and 1 times the spacing.

  6. Climate change and glacier retreat from 1955 to 2006 on Cilo Mountains, Southeast Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Yeşilyurt, Serdar; Uǧur, Doǧan; Kılar, Hatice

    2013-04-01

    Alpine glaciers are amongst key indicators of global-scale climate changes because of their natural dynamics and quick response to global warming. Although there is vast number of studies on recent glaciers of the world, less attention has been paid to the glaciers of Turkey and the Middle East. In the present study, present glaciers of Cilo Mountains (4135 m) located in Southeast Anatolia, one of the most important recent glacier areas of Turkey, is dealt with within the context of the impacts of climatic changes on glaciers. Based on aerial photographs taken in 1955, 1968 and 1988 together with Quickbird satellite images taken in 2006, four main stages were examined using remote sensing and GIS technologies. The paleo-glacier cover of the Last Glacial age (most likely the Last Glacial Maximum) on the Cilo Range was about 100 km² in area as compared to the actual glaciers found in the three valley system around Uludoruk summit with an area of only 5.6 km². Actual glacier have retreated between 100 and 360 m in the period from 1955 to 2006. According to elevation, thickness-mass characteristics of the glaciers and geomorphic conditions of their cirques, retreat rates were found to be between 2 and 7 m/yr. The ages of young terminal moraines were also calculated on the basis of annual decline rates of these glaciers. Consequently, the oldest moraines should have probably been deposited between 1850 and 1870 matching end of the Little Ice Age. This age is compatible with the glacier retreat of the European Alps. We determined a warming trend both in summer temperatures and annual averages based on data from three meteorological stations located in the vicinity of this mountain area. Keywords: Cilo Mountains, actual glacier, glacier retreat, climate change, Little Ace Age, Turkey

  7. Satellite Observations of Glacier Advances and Retreat in the Western Karakoram

    NASA Astrophysics Data System (ADS)

    Haritashya, U. K.; Bishop, M. P.; Shroder, J. F.; Bulley, H. N.

    2007-12-01

    Debris-covered alpine glaciers around the world have been retreating and downwasting. This suggests glacier response to atmospheric warming. Recent studies in the eastern Himalaya have shown systematic retreat for many glaciers. In the western Himalaya, however, systematic and quantitative data are not yet available to determine glacier sensitivity and mass balance trend. Given the paucity of bench-mark glaciers in the Himalaya, remote-sensing-based studies are required to obtain baseline information and produce estimates of advance and retreat rates. Consequently, our objectives were to assess glacier fluctuations in the western Karakoram of Pakistan as a part of the Global Land Ice Measurements from Space (GLIMS) project. Specifically, we used multi- temporal satellite data (ASTER 09/13/2004, Landsat TM 10/15/1992, and Landsat MSS 07/15/1992) to quantitatively assess terminus fluctuations. Results indicate that more than 50 percent of the sampled large and large-medium sized glaciers are advancing, and/or exhibit similar terminus positions to past positions. For example, Bualtar Glacier is advancing at the rate of 11 m/yr. On the other hand, most of the small-medium to small glaciers, such as Mani Glacier are retreating (15 m/yr). Some of these glaciers have also shown strong downwasting characteristics in the form of increased frequency and size of supraglacial lakes. Collectively, our results indicate that these glaciers may be responding differently to the current climatic conditions than in the eastern Himalaya (east of the Karakoram) and Wakhan Pamir region (northwest of the Karakoram). These quantitative results from remote-sensing studies also indicate that glacier fluctuations in this region are spatially and temporally complex. These complexities may be governed by multi-scaled topographic effects, as well as by variations in winter precipitation and decreases in summer temperature from increased cloudiness, as suggested by others.

  8. Retreatment of a transfer patient with bialveolar protrusion with mini bone-plate anchorage.

    PubMed

    Bilodeau, John E

    2014-10-01

    A 40-year-old black woman, with pretorqued, preangulated appliances on the maxillary teeth, transferred with chief concerns of missing teeth and her orthodontic progress. She had bialveolar protrusion and edentulous areas in both the maxilla and the mandible. After records were made and her desires assessed, she was retreated with the extraction of 3 premolars. Her protrusion was reduced and all edentulous spaces were closed. The facial change was evident due to the reduction of the protrusion. PMID:25263153

  9. Millennial Rates of Sea Cliff Retreat Derived From Cosmogenic 10Be and Coastal Platform Morphology

    NASA Astrophysics Data System (ADS)

    Hurst, M. D.; Ellis, M. A.; Rood, D. H.

    2014-12-01

    Observation of cliff erosion are often limited to relatively short timescales (a few decades), which are within the timeframe of anthropogenic modification of the coast and may be shorter than the recurrence interval for erosion events. Here we present long-term (centennial-millennial) averaged rates of sea cliff retreat for chalk cliffs in SE England derived from cosmogenic isotopes and coastal morphology. We determine long-term rates of sea cliff erosion from 10Be measured from in situ flint samples collected from three transects across the coastal platform in East Sussex. A numerical model of 10Be accumulation on an evolving coastal profile allows estimation of cliff retreat rate averaged over several hundred years. The model accounts for variation in 10Be accumulation with tides and sea-level rise, and takes into account platform downwear and topographic shielding by adjacent cliffs. Additionally, we use high-resolution (1m) multibeam bathymetry to map the extent of the coastal platform based on the surface texture in order to infer the position of the coast at ~8 ka. The difference in position to the current coastline provides estimates of Holocene-averaged rates of cliff erosion for all chalk cliffed coastline in the region. Comparison to historic records of cliff retreat reveals key similarities and differences between long and short-term signals. In certain locations, there are significant discrepancies (either faster or slower) between historic records and long-term rates of retreat. Each type of discrepancy may be the result of human interaction with the coastal environment, whether that interaction is local or non-local, and it is worthwhile noting that sites of relatively low historic rates of erosion are likely subject to high-magnitude, low-frequency failure events that could have devastating effects on human lives and infrastructure in areas that are considered to be low risk.

  10. On optimal retreat distance for the equivalent source method-based nearfield acoustical holography.

    PubMed

    Bai, Mingsian R; Chen, Ching-Cheng; Lin, Jia-Hong

    2011-03-01

    As a basic form of the equivalent source method (ESM) that is used to nearfield acoustical holography (NAH) problems, discrete monopoles are utilized to represent the sound field of interest. When setting up the virtual source distribution, it is vital to maintain a "retreat distance" between the virtual sources and the actual source surface such that reconstruction would not suffer from singularity problems. However, one cannot increase the distance without bound because of the ill-posedness inherent in the reconstruction process with large distance. In prior research, 1-2 times lattice spacing, or the inter-element distance of microphones, is generally recommended as retreat distance in using the ESM-based NAH. While this rule has shown to yield good results in many cases, the optimal choice is a complicated issue that depends on frequency, geometry of the physical source, content of evanescent waves, distribution of sensors and virtual sources, etc. This paper deals about attaining the best compromise between the reconstruction errors induced by the point source singularity; the reconstruction ill-posedness is an interesting problem in its own right. The paper revisits this issue, with the aid of an optimization algorithm based on the golden section search and parabolic interpolation. Numerical simulations were conducted for a baffled planar piston source and a spherically baffled piston source. The results revealed that the retreat distance appropriate for the ESM ranged from 0.4 to 0.5 times the spacing for the planar piston, while from 0.8 to 1.7 times average spacing for the spherical piston. Experiments carried out for a vibrating aluminum plate also revealed that the retreat distance with 0.5 times the spacing yielded better reconstructed velocity than those with 1/20 and 1 times the spacing. PMID:21428505

  11. Health-Related Quality of Life in Patients With Locally Advanced Prostate Cancer After 76 Gy Intensity-Modulated Radiotherapy vs. 70 Gy Conformal Radiotherapy in a Prospective and Longitudinal Study

    SciTech Connect

    Lips, Irene Dehnad, Human; Kruger, Arto Boeken; Moorselaar, Jeroen van; Heide, Uulke van; Battermann, Jan; Vulpen, Marco van

    2007-11-01

    Purpose: To compare quality of life (QoL) after 70 Gy conformal radiotherapy with QoL after 76 Gy intensity-modulated radiotherapy (IMRT) in patients with locally advanced prostate carcinoma. Methods and Materials: Seventy-eight patients with locally advanced prostate cancer were treated with 70 Gy three-field conformal radiotherapy, and 92 patients received 76 Gy IMRT with fiducial markers for position verification. Quality of life was measured by RAND-36, the European Organization for Research and Treatment of Cancer core questionnaire (EORTC QLQ-C30(+3)), and the prostate-specific EORTC QLQ-PR25, before radiotherapy (baseline) and 1 month and 6 months after treatment. Quality of life changes in time (baseline vs. 1 month and baseline vs. 6 months) of {>=}10 points were considered clinically relevant. Results: Differences between the treatment groups for QoL changes over time occurred in several QoL domains. The 76-Gy group revealed no significant deterioration in QoL compared with the 70-Gy group. The IMRT 76-Gy group even demonstrated a significantly better change in QoL from baseline to 1 month in several domains. The conformal 70-Gy group revealed temporary deterioration in pain, role functioning, and urinary symptoms; for the IMRT 76-Gy group a better QoL in terms of change in health existed after 1 month, which persisted after 6 months. For both treatment groups temporary deterioration in physical role restriction occurred after 1 month, and an improvement in emotional role restriction occurred after 6 months. Sexual activity was reduced after treatment for both groups and remained decreased after 6 months. Conclusions: Intensity-modulated radiotherapy and accurate position verification seem to provide a possibility to increase the radiation dose for prostate cancer without deterioration in QoL.

  12. Diachronous retreat of the Greenland ice sheet during the last deglaciation

    NASA Astrophysics Data System (ADS)

    Sinclair, G.; Carlson, A. E.; Mix, A. C.; Lecavalier, B. S.; Milne, G.; Mathias, A.; Buizert, C.; DeConto, R.

    2016-08-01

    The last deglaciation is the most recent interval of large-scale climate change that drove the Greenland ice sheet from continental shelf to within its present extent. Here, we use a database of 645 published 10Be ages from Greenland to document the spatial and temporal patterns of retreat of the Greenland ice sheet during the last deglaciation. Following initial retreat of its marine margins, most land-based deglaciation occurred in Greenland following the end of the Younger Dryas cold period (12.9-11.7 ka). However, deglaciation in east Greenland peaked significantly earlier (13.0-11.5 ka) than that in south Greenland (11.0-10 ka) or west Greenland (10.5-7.0 ka). The terrestrial deglaciation of east and south Greenland coincide with adjacent ocean warming. 14C ages and a recent ice-sheet model reconstruction do not capture this progression of terrestrial deglacial ages from east to west Greenland, showing deglaciation occurring later than observed in 10Be ages. This model-data misfit likely reflects the absence of realistic ice-ocean interactions. We suggest that oceanic changes may have played an important role in driving the spatial-temporal ice-retreat pattern evident in the 10Be data.

  13. Ecosystem response to a temporary sea ice retreat in the Bering Sea: Winter 2009

    NASA Astrophysics Data System (ADS)

    Miksis-Olds, Jennifer L.; Stabeno, Phyllis J.; Napp, Jeffery M.; Pinchuk, Alexei I.; Nystuen, Jeffrey A.; Warren, Joseph D.; Denes, Samuel L.

    2013-04-01

    Adding acoustic systems onto ocean moorings and observatories provides additional data to more fully document ecosystem responses to environmental perturbations. A passive acoustic recorder and three-frequency echosounder system were integrated into a biophysical mooring on the central eastern Bering Sea continental shelf. An unexpected, transient, mid-winter retreat of the seasonal sea ice was observed over the mooring for a 2-week period in March 2009. Interpretation of the passive acoustic data provided information about sea ice conditions and included the detection and identification of vocalizing marine mammals, while the acoustic backscatter provided information on relative zooplankton and fish abundance before, during, and after the retreat. Hydrographic data confirmed the acoustic signal was associated with changing surface ice conditions, and the combined information from the biophysical mooring sensors revealed changes in winter trophic level dynamics during the retreat, which would have otherwise been undetected by traditional ship-based observations. Changes in the acoustic environment, zooplankton dynamics, and acoustic detection of marine mammals were observed amidst a physically stable and uniform water column with no indication of a phytoplankton bloom. These data demonstrate the value of acoustic technologies to monitor changing ecosystems dynamics in remote and hazardous locations.

  14. The effect of chloroform, orange oil and eucalyptol on root canal transportation in endodontic retreatment.

    PubMed

    Karataş, Ertuğrul; Kol, Elif; Bayrakdar, İbrahim Şevki; Arslan, Hakan

    2016-04-01

    The purpose of the present study was to assess the effect of solvents on root canal transportation in endodontic retreatment. Sixty extracted human permanent mandibular first molars with curved root canals were selected. All of the root canals were prepared using Twisted File Adaptive instruments (SybronEndo, Orange, CA, USA) and filled with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) using the cold lateral compaction technique. The teeth were assigned to four retreatment groups as follows (n = 15): eucalyptol, chloroform, orange oil and control. The canals were scanned using cone-beam computed tomography scanning before and after instrumentation. The chloroform group showed a significantly higher mean transportation value than the orange oil and control groups at the 3 and 5 mm levels (P = 0.011 and P = 0.003, respectively). There was no significant difference among the orange oil, eucalyptol and control groups in terms of canal transportation (P > 0.61). The chloroform led to more canal transportation than the eucalyptol and orange oil during endodontic retreatment. PMID:26420757

  15. Dating New York - Tracking the Retreat of the Laurentide Ice Sheet

    NASA Astrophysics Data System (ADS)

    Edwards, A. R.; Schaefer, J.; Rinterknecht, V.; Ivy-Ochs, S.

    2004-12-01

    The Laurentide Ice Sheet (LIS) covered the New York City area during the Last Glacial Maximum (LGM) and when it retreated carved out the present topography, exposing fresh bedrock. Although modernization has led to the modification of much of the present landscape, the New York area still features many attributes of the glacial sculpting. These attributes: glacially polished bedrock, erratic boulders and glacial moraines, remain as evidence of past climate change. Long Island represents a terminal moraine of the LIS, while areas in Central Park, Inwood (northern Manhattan) and the Hudson valley display beautiful retreat features. We present surface exposure dates of samples removed from these areas from the measurement of 10Be in them. This allows us to better understand the dynamics of the Laurentide Ice Sheet at the end of the last ice age. We will match the data with existing moraine records from the LIS as well as with mountain glacier records to determine whether or not (i) the LIS and the Scandinavian Ice Sheet were in sync; (ii) the huge LIS reacted more inertial than smaller systems to the climate reorganizations; (iii) the retreat pattern of the LIS.

  16. 14 CFR 25.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and maximum...: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the airplane and perpendicular to the plane of symmetry of the airplane)...

  17. 14 CFR 29.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... terms of minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and... requirements: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the rotorcraft and perpendicular to the plane of symmetry of...

  18. 14 CFR 29.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... terms of minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and... requirements: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the rotorcraft and perpendicular to the plane of symmetry of...

  19. 14 CFR 27.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and maximum...: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the rotorcraft and perpendicular to the plane of symmetry of the...

  20. 14 CFR 27.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and maximum...: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the rotorcraft and perpendicular to the plane of symmetry of the...

  1. 14 CFR 29.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... terms of minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and... requirements: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the rotorcraft and perpendicular to the plane of symmetry of...

  2. 14 CFR 25.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and maximum...: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the airplane and perpendicular to the plane of symmetry of the airplane)...

  3. 14 CFR 27.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and maximum...: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the rotorcraft and perpendicular to the plane of symmetry of the...

  4. 14 CFR 25.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and maximum...: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the airplane and perpendicular to the plane of symmetry of the airplane)...

  5. 14 CFR 25.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and maximum...: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the airplane and perpendicular to the plane of symmetry of the airplane)...

  6. 14 CFR 29.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... terms of minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and... requirements: (1) Intensities in the horizontal plane. Each intensity in the horizontal plane (the plane containing the longitudinal axis of the rotorcraft and perpendicular to the plane of symmetry of...

  7. Retreat of the Puget lobe of the Cordilleran Ice Sheet (Invited)

    NASA Astrophysics Data System (ADS)

    Haugerud, R. A.

    2010-12-01

    Systematic geomorphic mapping from high-resolution, digital lidar topography (e.g., http://pubs.usgs.gov/of/2009/1033/) is improving our understanding of the retreat of the Cordilleran ice sheet at the end of the last glaciation of northwest Washington. This history is of interest both because it provides a stratigraphic framework for earthquake-hazards studies and as an example of the interaction of grounded marine ice with rising sea level. The spatial distribution of outwash flats outlines a four-stage history of ice-margin retreat. Main stage is marked by drainage from the south margin of the Puget Lobe to the Chehalis valley via multiple channels. Russell stage began when ice retreated sufficiently for drainage to coalesce to a single path via Black Lake south of Olympia. Bretz stage began with a drop in local base level as ice-marginal drainage switched to a path across the Chimacum Peninsula southeast of Port Townsend. Whulge stage began when ice retreated from Admiralty Inlet, Glacial Lake Bretz drained, and Puget Sound became marine. A 5th, Sumas stage could be defined but ongoing work in the Bellingham area indicates that we don’t yet fully understand Sumas complexities. An apparently-folded outwash flat west of Bremerton provides what may be our best constraint on the frequency of large earthquakes on the Seattle fault (≥23 m differential uplift in ~16,000 years, or one 7-9 m uplift event per ~5,000 yrs); the weakest link in this argument is the assumption of southwards drainage from the retreating Puget Lobe. Several lines of evidence indicate that the Puget Lobe stagnated and melted in place: widespread dead-ice features; absence of end moraines between Olympia and central Whidbey Island; peculiarities in the outfall of Glacial Lake Bretz; and re-orientation of ice flow on northern Whidbey Island from N-S to NE-SW. Stagnation was likely caused by collapse of the Juan de Fuca lobe, which beheaded the Puget Lobe. Collapse was probably the result of a

  8. Asynchronous ice lobe retreat and glacial Lake Bascom: Deglaciation of the Hoosic and Vermont valleys, southwestern Vermont

    SciTech Connect

    Small, E.; Desimone, D. . Dept. of Geology)

    1993-03-01

    Deglaciation of the Hoosic River drainage basin in southwestern Vermont was more complex than previously described. Detailed surficial mapping, stratigraphic relationships, and terrace levels/delta elevations reveal new details in the chronology of glacial Lake Bascom: (1) a pre-Wisconsinan proglacial lake was present in a similar position to Lake Bascom as ice advanced: (2) the northern margin of 275m (900 ft) glacial Lake Bascom extended 10 km up the Vermont Valley; (3) the 215m (705 ft) Bascom level was stable and long lived; (4) intermediate water planes existed between 215m and 190m (625 ft) levels; and (5) a separate ice tongue existed in Shaftsbury Hollow damming a small glacial lake, here named glacial Lake Emmons. This information is used to correlate ice margins to different lake levels. Distance of ice margin retreat during a lake level can be measured. Lake levels are then used as control points on a Lake Bascom relative time line to compare rate of retreat of different ice tongues. Correlation of ice margins to Bascom levels indicates ice retreat was asynchronous between nearby tongues in southwestern Vermont. The Vermont Valley ice tongue retreated between two and four times faster than the Hoosic Valley tongue during the Bascom 275m level. Rate of retreat of the Vermont Valley tongue slowed to one-half of the Hoosic tongue during the 215m--190m lake levels. Factors responsible for varying rates of retreat are subglacial bedrock gradient, proximity to the Hudson-Champlain lobe, and the presence of absence of a calving margins. Asynchronous retreat produced splayed ice margins in southwestern Vermont. Findings from this study do not support the model of parallel, synchronous retreat proposed by many workers for this region.

  9. Pattern and timing of retreat of the last British-Irish Ice Sheet

    NASA Astrophysics Data System (ADS)

    Clark, Chris D.; Hughes, Anna L. C.; Greenwood, Sarah L.; Jordan, Colm; Sejrup, Hans Petter

    2012-06-01

    During the last glacial the ice sheet that subsumed most of Britain, Ireland and the North Sea attained its maximum extent by 27 ka BP and with an ice volume sufficient to raise global sea level by ca 2.5 m when it melted. We reconstruct the demise of this British-Irish Ice Sheet (BIIS) and present palaeo-glaciological maps of retreat stages between 27 and 15 ka BP. The whole land area was investigated using remote sensing data and we present maps of moraines, meltwater channels, eskers, and drumlins and a methodology of how to interpret and bring them together. For the continental shelf, numerous large moraines were discovered recording an extensive pattern of retreat stretching from SW Ireland to the Shetland Isles. From an integration of this new mapping of glacial geomorphology (>26,000 landforms) with previously published evidence, compiled in the BRITICE database, we derive a pattern of retreat for the whole BIIS. We review and compile relevant dates (881 examples) that constrain the timing of retreat. All data are held within a Geographic Information System (GIS), and are deciphered to produce a best-estimate of the combined pattern and timing of retreat. Pattern information reveals an ice sheet mainly comprised of a shelf-parallel configuration from SW Ireland to NE Scotland but it spread far enough to the south to incorporate outlying ice domes over Wales, the Lake District and Kerry. Final disintegration was into a number of separate ice caps, rather than reduction as a single mass, and paradoxically, retreat was not always back to high ground. By 23 ka BP ice withdrew along its northern boundaries at the same time as the southern margins were expanding, including transient ice streaming down the Irish Sea and advances of lobes in the Cheshire Basin, Vale of York and east coast of England. Ice divides migrated south. By 19 ka the ice sheet was in crisis with widespread marine-based ice losses, particularly in the northern North Sea and the Irish Sea

  10. Eocene sea retreat out of Asia: paleogeography, controlling mechanisms and environmental impacts

    NASA Astrophysics Data System (ADS)

    Dupont-Nivet, Guillaume; Bosboom, Roderic; Proust, Jean-Noël; Mandic, Oleg; Villa, Giuliana; Grothe, Arjan; Stoica, Marius; Guo, Zhaojie; Krijgsman, Wout; Yang, Wei; Bougeois, Laurie; Aminov, Jovid; Ormukov, Cholponbec; Huang, Wentao

    2014-05-01

    The sediments of the Central Asian basins include the remnants of the easternmost extent of a large epicontinental sea. Before it retreated westward and eventually separated as the Paratethys Sea following the Eocene-Oligocene transition (EOT), this shallow marine sea extended across the Eurasian continent from the Mediterranean Tethys in the west to the Tarim Basin in western China in the east. However, the paleogeography and the timing of the westward retreat of the proto-Paratethys Sea are too poorly constrained to identify its proposed controlling mechanisms and paleoenvironmental impacts. The sea supposedly entered Central Asia in the Cretaceous and five third-order marine incursions have been recognized from the Cretaceous-Paleogene sedimentary record, of which the last two transgressions are documented here. We studied the sea retreat in the Tarim Basin in western China, the Alai Valley and Ferghana Basin in southern Kyrgyzstan and the Afghan-Tajik Basin in south-western Tajikistan. Integrated bio-magnetostratigraphic dating shows that the sea retreated westward from the Tarim Basin in stepwise fashion. The major fourth transgression occurred during the Lutetian, after which the sea retreated from the southwest Tarim Basin paleodepocenter at ~41 Ma (base C18r). The last and fifth transgression was restricted to the westernmost margin of the Tarim basin and occurred during latest Bartonian-early Priabonian (base C17n.3n-base C16n.1n). At the level of precision of our dating, each of these marine incursions is apparently synchronous across the Tarim Basin suggesting rapid regional transgression/regression cycles in these shallow epicontinental basins with limited diachroneity. The shallow marine near-shore sediments of these last two transgressions can be convincingly correlated by litho- and biostratigraphy across Central Asia, showing for the first time that the sea may have largely retreated from Central Asia in the late Eocene. The lack of apparent

  11. Cost-effectiveness of retreatment with varenicline after failure with or relapse after initial treatment for smoking cessation

    PubMed Central

    Annemans, Lieven; Marbaix, Sophie; Nackaerts, Kristiaan; Bartsch, Pierre

    2015-01-01

    Objectives A recent trial showed the clinical benefit of retreatment with varenicline in subjects failing on the initial treatment, or relapsing after initial success. The objective of this study was to evaluate the cost-effectiveness of retreatment with varenicline compared with other smoking cessation interventions. Methods A published Markov model was adapted to compare one quit attempt of varenicline followed by retreatment to treatment/retreatment with nicotine replacement therapy (NRT), bupropion or placebo, and with only 1 quit attempt of varenicline. Efficacy was obtained from clinical trials. Incidence of smoking-related diseases was based on published data. Cost of therapies and complications was obtained from databases and literature. Results For 1000 smokers willing to quit, varenicline retreatment saves 275,000€, 118,000€, 316,000€ and 237,000€ compared to NRT, bupropion, placebo, or one single varenicline quit attempt respectively at lifetime and from the healthcare payer perspective. The number of quality adjusted life years gained is 74, 63, 193 and 111 respectively. Sensitivity analyses showed the robustness of these findings. Conclusion This analysis suggests that in the long term, varenicline retreatment is a dominant intervention, meaning both greater health gains and greater costs saved, over other possible interventions and therefore should be considered as a standard option. PMID:26844072

  12. Scholarly Retreat

    ERIC Educational Resources Information Center

    Boyle, Robert R.; Pellegrini, Barbara J.; McGrew, Jean B.

    2003-01-01

    Advanced placement teachers around Chicago find their own intellectual stimulation reinvigorates their teaching and benefits their students. Through a consortium, these teachers group together to explore content-based topics using a rich variety of community resources, including a top library, university and museum resources. "This is my…

  13. Longitudinal Magnification Drawing Mistake

    NASA Astrophysics Data System (ADS)

    Rabal, Héctor; Cap, Nelly; Trivi, Marcelo

    2004-01-01

    Lateral magnification in image formation by positive lenses, mirrors, and dioptrics is usually appropriately developed in most optics textbooks.1-9 However, the image of a three-dimensional object occupies a three-dimensional region of space. The optical system affects both the transverse and the longitudinal dimensions of the object and, in general, does it in different ways. The magnification in the direction of the optical axis (the longitudinal magnification) is seldom treated. In several texts, the concept of longitudinal magnification is not even considered. Symmetrical objects (such as arrows) are used and their images appear laterally inverted. It is not shown how a longitudinally nonsymmetric object is imaged. One of the few books where this subject is well treated is in the textbook by Hecht.10 We have repeatedly verified in our classes that there is some confusion related to this subject. Students tend to believe that the image is longitudinally symmetric with respect to the lens optic center. Some prestigious texts commit the same mistake. In addition, a very nice optics book,11 a catalogue of optical hardware,12 a worldwide scientific magazine,13 a paper in an optics journal,14 and a Spanish encyclopedia,15 for example, have also been found to contain this error in drawing the image of a three-dimensional object formed by a positive lens. In this paper we suggest that the teaching of longitudinal magnification should be done with some care and we include a figure showing a properly drawn image.

  14. BRITICE-CHRONO: Constraining retreat of the last British-Irish Ice Sheet using luminescence geochronometry

    NASA Astrophysics Data System (ADS)

    Duller, Geoff; Smedley, Rachel; Bateman, Mark; Medialdea, Alicia; Chiverrell, Richard; Fabel, Derek; Clark, Chris; Consortium, Britice-Chrono

    2016-04-01

    The BRITICE-CHRONO project funded by NERC is a multi-million pound consortium designed to use multiple geochronometers to constrain the rate of retreat of the major outlets of the last British-Irish Ice Sheet (BIIS) at the end of the last glacial cycle. Cosmogenic isotopes, radiocarbon and luminescence dating methods are being applied to materials sampled along lines of ice retreat. Luminescence dating for this project has targeted glaciofluvial sediments associated with ice retreat and over 150 samples from around the British Isles have been analysed in two laboratories. All samples have been analysed using small aliquot or single grain measurements of quartz optically stimulated luminescence (OSL). The resulting dose distributions have been modelled to obtain the depositional age. The major challenges in the application of quartz OSL can be grouped into two categories: signal characteristics and statistical characterisation of dose distributions. Samples have been collected over the entire British Isles and have very variable characteristics. Some samples give bright OSL signals, whilst in other areas the quartz is dim. A pervasive problem is the occurrence of grains which appear to be quartz but which are sensitive to infrared stimulation. Effective screening of these grains is essential to avoid dose underestimation. The second challenge has been estimating appropriate numerical parameters for application of minimum age models. Extensive dose recovery experiments have been undertaken to form the basis for estimates of overdispersion, and in some areas these show highly variable luminescence characteristics. The reproducibility of the analyses undertaken has been assessed through an intercomparison between the two luminescence laboratories and the results of this exercise will be discussed.

  15. Evaluation of image-guided helical tomotherapy for the retreatment of spinal metastasis

    SciTech Connect

    Mahan, Stephen L. . E-mail: s_mahan_phd@yahoo.com; Ramsey, Chester R.; Scaperoth, Daniel D.; Chase, Daniel J.; Byrne, Thomas E.

    2005-12-01

    Introduction: Patients with vertebral metastasis that receive radiation therapy are typically treated to the spinal cord tolerance dose. As such, it is difficult to successfully deliver a second course of radiation therapy for patients with overlapping treatment volumes. In this study, an image-guided helical tomotherapy system was evaluated for the retreatment of previously irradiated vertebral metastasis. Methods and Materials: Helical tomotherapy dose gradients and maximum cord doses were measured in a cylindrical phantom for geometric test cases with separations between the planning target volume (PTV) and the spinal cord organ at risk (OAR) of 2 mm, 4 mm, 6 mm, 8 mm, and 10 mm. Megavoltage computed tomography (CT) images were examined for their ability to localize spinal anatomy for positioning purposes by repeat imaging of the cervical spine in an anthropomorphic phantom. In addition to the phantom studies, 8 patients with cord compressions that had received previous radiation therapy were retreated to a mean dose of 28 Gy using conventional fractionation. Results and Discussion: Megavoltage CT images were capable of positioning an anthropomorphic phantom to within {+-}1.2 mm (2{sigma}) superior-inferiorly and within {+-}0.6 mm (2{sigma}) anterior-posteriorly and laterally. Dose gradients of 10% per mm were measured in phantom while PTV uniformity indices of less than 11% were maintained. The calculated maximum cord dose was 25% of the prescribed dose for a 10-mm PTV-to-OAR separation and 71% of the prescribed dose for a PTV-to-OAR separation of 2 mm. Eight patients total have been treated without radiation-induced myelopathy or any other adverse effects from treatment. Conclusions: A technique has been evaluated for the retreatment of vertebral metastasis using image-guided helical tomotherapy. Phantom and patient studies indicated that a tomotherapy system is capable of delivering dose gradients of 10% per mm and positioning the patient within 1.2 mm

  16. Exploring tidewater glacier retreat using past and current observations at Columbia Glacier, Alaska. (Invited)

    NASA Astrophysics Data System (ADS)

    O'Neel, S.; Pfeffer, W. T.; Howat, I. M.; Conway, H.; Columbia Glacier Consortium

    2010-12-01

    Since fulfilling Austin Post’s prediction of impending retreat in the late 1970s, Columbia Glacier has repeatedly surprised both casual and careful observers with its ability for rapid change. Over the last three decades, Columbia Glacier has lost approximately 18 km of its original 66 km length, while thinning by approximately 50% at the present terminus. The total ice volume lost to the Gulf of Alaska Estimates upwards of 120 km3 constrain the total ice volume lost to the Gulf of Alaska. Recently, the terminus supported a ~1.5 km long floating tongue for over than a year, contradicting the common assumption that the mechanical properties of temperate ice prohibit flotation over sustained time intervals. The rich history of study offers an opportunity to better understand tidewater glacier retreat, and a valuable analog to the dynamic instability underway at several ice sheet outlet glaciers. Current research aims to improve processing resolution of existing aerial photographic data, while complimenting the 30-year photogrammetric record with a suite of field observations. Recent instrumentation includes: oblique time lapse and still imagery, semi-permanent GPS, airborne radar, mass balance, passive seismology and LiDAR. This presentation will focus on innovative methods developed in recent field seasons, sharing insight each has provided into the retreat process . 1The Columbia Glacier Consortium consists of: Fabian Walter (SIO), Kenichi Matsuoka (NPI), Ben Smith (UW), Ethan Welty (CU-Boulder), Chris Larsen (UAF), Dave Finnegan (CRREL), Dan McNamara (USGS), Yushin Ahn (OSU), Julie Markus (OSU), Adam LeWinter (EIS).

  17. Glacier Retreat in the Southern Peruvian Andes: Climate Change, Environmental Impacts, Human Perception and Social Response

    NASA Astrophysics Data System (ADS)

    Orlove, B.

    2007-12-01

    This paper presents results from recent environmental and anthropological research near glacierized areas in the department of Cusco, Peru, home to the well-known Quelccaya Ice Cap and to the peak of Ausangate (6384 m). Glaciers in the region are in negative mass balance, losing volume and area, with upslope movement of the glacier fronts. Somewhat paradoxically, flows in many streams close to the glaciers are reduced, particularly in the dry season, due to a shift in the seasonal distribution of melting, to increased evaporation and to increased percolation into newly-exposed sands and gravels. Associated with this reduction in flow is a desiccation of some anthropogenic and natural wetlands, reducing the availability of dry season forage to wild (vicuna) and domesticated (alpaca, llama) ruminants. Interviews and ethnographic observations with local populations of Quechua-speaking herders at elevations of 4500-5200 meters provide detailed comments on these changes. They have an extensive vocabulary of terms for glacial features associated with retreat. They link this treat with environmental factors (higher temperatures, greater winds that deposit dust on lower portions of glaciers) and with religious factors (divine punishment for human wrong-doing, failure of humans to respect mountain spirits). They describe a variety of economic and extra-economic impacts of this retreat on different spatial, social and temporal scales. Though they face other issues as well (threats of pollution from new mining projects, inadequacy of government services), glacier retreat is their principal concern. Many herders express extreme distress over this unprecedented threat to their livelihoods and communities, though a few propose responses - out-migration, the formation of an association of neighboring communities, development of irrigation works - that could serve as adaptations.

  18. Tracking Retreat of the North Seasonal Ice Cap on Mars: Results from the THEMIS Investigation

    NASA Technical Reports Server (NTRS)

    Ivanov, A. B.; Wagstaff, K. L.; Ttus, T. N.

    2005-01-01

    The CO2 ice caps on Mars advance and retreat with the seasons. This phenomenon was first observed by Cassini and then confirmed by numerous ground based observations in 19th and 20th centuries. With the advent of the space age observations of the seasonal ice cap were done by all orbiting spacecraft starting with Mariner 7. Viking Orbiters and more recently the Mars Global Surveyor (particularly Mars Orbiter Camera (MOC) and Thermal Emission Spectrometer (TES) instruments) have accumulated significant data on the retreat of the CO2 seasonal cap. During Mars year 2 of THEMIS operations at Mars, we planned an observational campaign in which the THEMIS instrument (onboard the Mars Odyssey spacecraft) repeatedly observed the north seasonal polar cap from midwinter to late spring. THEMIS allows simultaneous observations in both Thermal IR (12.57 m) and Visible wavelengths (0.65 m). One of the goals for this work is to initiate an interannual program for observations of the seasonal ice caps using the THEMIS instrument. The most efficient way to detect the edge between frost and bare ground is directly onboard of the spacecraft. Prior to onboard software design effort, we have developed two groundbased algorithms for automatically finding the edge of the seasonal polar cap in THEMIS IR data. The first algorithm relies on fully calibrated data and can be used for highly reliable groundbased analyses. The second method was specifically developed for processing raw, uncalibrated data in a highly efficient way. It has the potential to enable automatic, onboard detections of the seasonal cap retreat. We have experimentally confirmed that both methods produce similar results, and we have validated both methods against a model constructed from the MGS TES data from the same season.

  19. Early ice retreat and ocean warming may induce copepod biogeographic boundary shifts in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Feng, Zhixuan; Ji, Rubao; Campbell, Robert G.; Ashjian, Carin J.; Zhang, Jinlun

    2016-08-01

    Early ice retreat and ocean warming are changing various facets of the Arctic marine ecosystem, including the biogeographic distribution of marine organisms. Here an endemic copepod species, Calanus glacialis, was used as a model organism, to understand how and why Arctic marine environmental changes may induce biogeographic boundary shifts. A copepod individual-based model was coupled to an ice-ocean-ecosystem model to simulate temperature- and food-dependent copepod life history development. Numerical experiments were conducted for two contrasting years: a relatively cold and normal sea ice year (2001) and a well-known warm year with early ice retreat (2007). Model results agreed with commonly known biogeographic distributions of C. glacialis, which is a shelf/slope species and cannot colonize the vast majority of the central Arctic basins. Individuals along the northern boundaries of this species' distribution were most susceptible to reproduction timing and early food availability (released sea ice algae). In the Beaufort, Chukchi, East Siberian, and Laptev Seas where severe ocean warming and loss of sea ice occurred in summer 2007, relatively early ice retreat, elevated ocean temperature (about 1-2°C higher than 2001), increased phytoplankton food, and prolonged growth season created favorable conditions for C. glacialis development and caused a remarkable poleward expansion of its distribution. From a pan-Arctic perspective, despite the great heterogeneity in the temperature and food regimes, common biogeographic zones were identified from model simulations, thus allowing a better characterization of habitats and prediction of potential future biogeographic boundary shifts.

  20. Modeling the cliff retreat response to base-level change in layered rocks, Colorado Plateau, USA

    NASA Astrophysics Data System (ADS)

    Ward, D.; Sheehan, C.

    2015-12-01

    The retreat of cliffs is an important mode of erosion in layered rocks of variable strength. For example, the iconic Colorado Plateau landscapes of Grand Canyon, Canyonlands, and Monument Valley owe their unique forms to this process. These landscapes are the end result of incision by trunk streams followed by cliff retreat. Local interactions between stochastic rockfall and first-order channels draining a cliff regulate the cliff retreat response to a base-level fall. However, nonlinear transport dynamics, steep slopes, and variable rock strength challenge the modeling of landscape evolution in these settings. Here, we employ structure-from-motion photogrammetry to generate high-resolution DTMs of a natural experiment site on the Colorado Plateau. The site features a simple, sandstone-over-shale stratigraphy with a continuous gradient in cliffband height and evidence for an ongoing transient response to base level fall. The terrain data inform a high-resolution (dx=5 m), 2D numerical model of cliffband erosion. The model simulates the interaction of three primary processes: fluvial erosion and sediment transport; hillslope transport of regolith, including shallow landsliding; and rockfall from resistant units. Crucially, the model allows us to modify stratigraphy arbitrarily to examine the landscape response to parameters such as thickness, spacing, and dip of resistant units. Results indicate that the contrast in fluvial erodibility sets the pattern of emergence of cliffs as a resistant layer is exhumed, while the difference in weathering rates across rock types sets the rate at which cliffs emerge. Once rockfall begins, erosion rates are modified by the thickness of the resistant layer, which sets the volume of rockfall debris reaching the channels below the cliff. The modeling highlights the need for process-based understanding of the conditions for cliff failure by rockfall and redistribution of the debris in very steep, rapidly-eroding landscapes.

  1. Improved age constraints for the retreat of the Irish Sea Ice Stream

    NASA Astrophysics Data System (ADS)

    Smedley, Rachel; Chiverrell, Richard; Duller, Geoff; Scourse, James; Small, David; Fabel, Derek; Burke, Matthew; Clarke, Chris; McCarroll, Danny; McCarron, Stephen; O'Cofaigh, Colm; Roberts, David

    2016-04-01

    BRITICE-CHRONO is a large (> 45 researchers) consortium project working to provide an extensive geochronological dataset constraining the rate of retreat of a number of ice streams of the British-Irish Ice Sheet following the Last Glacial Maximum. When complete, the large empirical dataset produced by BRITICE-CHRONO will be integrated into model simulations to better understand the behaviour of the British-Irish Ice Sheet in response to past climate change, and provide an analogue for contemporary ice sheets. A major feature of the British-Irish Ice Sheet was the dynamic Irish Sea Ice Stream, which drained a large proportion of the ice sheet and extended to the proposed southern limit of glaciation upon the Isles of Scilly (Scourse, 1991). This study will focus on a large suite of terrestrial samples that were collected along a transect of the Irish Sea basin, covering the line of ice retreat from the Isles of Scilly (50°N) in the south, to the Isle of Man (54°N) in the north; a distance of 500 km. Ages are determined for both the eastern and western margins of the Irish Sea using single-grain luminescence dating (39 samples) and terrestrial cosmogenic nuclide dating (10 samples). A Bayesian sequence model is then used in combination with the prior information determined for deglaciation to integrate the geochronological datasets, and assess retreat rates for the Irish Sea Ice Stream. Scourse, J.D., 1991. Late Pleistocene stratigraphy and palaeobotany of the Isles of Scilly. Philosophical Transactions of the Royal Society of London B334, 405 - 448.

  2. Autocyclic Formation, Retreat, and Destruction of Waterfalls in an Experimental Bedrock Channel

    NASA Astrophysics Data System (ADS)

    Scheingross, J. S.; Fuller, B. M.; Lamb, M. P.

    2015-12-01

    Waterfalls are ubiquitous in steep landscapes and have been documented to retreat upstream at rates far outpacing standard fluvial incision into bedrock. While the formation of waterfalls following changes in climate and base-level lowering have been well-documented, little work has explored the formation of waterfalls via the internal dynamics from interacting flow hydraulics, sediment flux, and evolving channel morphology. Distinguishing between waterfalls formed via external versus internal forcing is important, as waterfall formation and retreat rate is often applied in inverse to determine the timing of external forcing. Here, we present results from a laboratory experiment designed to explore channel incision and waterfall formation. We fed water and sediment at constant rates over an initially planar surface at 19.5% slope. A channel rapidly incised into the artificial bedrock substrate, and small-wavelength variations in erosion rate created steps and pools which grew in amplitude. As pools deepened, erosion was focused on the upstream pool faces creating steep segments in the channel bed. At the topographic breaks between these steep segments and their upstream treads, water detached from the bed forming ventilated waterfall jets which impacted the plunge pools below. Continued pool deepening led to sediment deposition on the pool floors, locally inhibiting vertical incision while the upstream and downstream surfaces were free to erode. Amplified erosion at the waterfall lip incised a new pool into the bedrock previously composing the waterfall face while simultaneous lowering of the downstream pool lip resulted in the destruction of the original pool. Repetition of this process in our experiment suggests that interactions between bedrock erosion and sediment cover can result in the formation of a series of plunge pools which retreat upstream, and that care must be taken to distinguish between autocyclic versus allocyclic waterfall formation in studies

  3. Long-term cliff retreat and erosion hotspots along the central shores of the Monterey Bay National Marine Sanctuary

    USGS Publications Warehouse

    Moore, Laura J.; Griggs, Gary B.

    2002-01-01

    Quantification of cliff retreat rates for the southern half of Santa Cruz County, CA, USA, located within the Monterey Bay National Marine Sanctuary, using the softcopy/geographic information system (GIS) methodology results in average cliff retreat rates of 7–15 cm/yr between 1953 and 1994. The coastal dunes at the southern end of Santa Cruz County migrate seaward and landward through time and display net accretion between 1953 and 1994, which is partially due to development. In addition, three critically eroding segments of coastline with high average erosion rates ranging from 20 to 63 cm/yr are identified as erosion ‘hotspots’. These locations include: Opal Cliffs, Depot Hill and Manresa. Although cliff retreat is episodic, spatially variable at the scale of meters, and the factors affecting cliff retreat vary along the Santa Cruz County coastline, there is a compensation between factors affecting retreat such that over the long-term the coastline maintains a relatively smooth configuration. The softcopy/GIS methodology significantly reduces errors inherent in the calculation of retreat rates in high-relief areas (e.g. erosion rates generated in this study are generally correct to within 10 cm) by removing errors due to relief displacement. Although the resulting root mean squared error for erosion rates is relatively small, simple projections of past erosion rates are inadequate to provide predictions of future cliff position. Improved predictions can be made for individual coastal segments by using a mean erosion rate and the standard deviation as guides to future cliff behavior in combination with an understanding of processes acting along the coastal segments in question. This methodology can be applied on any high-relief coast where retreat rates can be measured.

  4. Investigators Retreat: A Forum to Bridge Frederick and Bethesda Cancer Research | Poster

    Cancer.gov

    By Andrea Frydl, Contributing Writer Nearly 700 researchers, scientists, and laboratory technicians convened in the Ronald Reagan Building and International Trade Center in Washington, DC, for the 2014 NCI Intramural Scientific Investigators Retreat on Jan. 14. The event featured presentations and posters exploring topics in cancer research from KRAS signaling to animal care. One of the highlights of the event was a presentation made by Valerie Beral, Ph.D., from University of Oxford, discussing “Rosalind Franklin and Cancer in Women.” 

  5. Eocene sea retreat out of Asia: paleogeography, controlling mechanisms and environmental impacts

    NASA Astrophysics Data System (ADS)

    Dupont-Nivet, Guillaume; Bosboom, Roderic; Proust, Jean-Noël; Mandic, Oleg; Villa, Giuliana; Grothe, Arjan; Stoica, Marius; Guo, Zhaojie; Krijgsman, Wout; Yang, Wei; Bougeois, Laurie; Aminov, Jovid; Ormukov, Cholponbec; Huang, Wentao

    2014-05-01

    The sediments of the Central Asian basins include the remnants of the easternmost extent of a large epicontinental sea. Before it retreated westward and eventually separated as the Paratethys Sea following the Eocene-Oligocene transition (EOT), this shallow marine sea extended across the Eurasian continent from the Mediterranean Tethys in the west to the Tarim Basin in western China in the east. However, the paleogeography and the timing of the westward retreat of the proto-Paratethys Sea are too poorly constrained to identify its proposed controlling mechanisms and paleoenvironmental impacts. The sea supposedly entered Central Asia in the Cretaceous and five third-order marine incursions have been recognized from the Cretaceous-Paleogene sedimentary record, of which the last two transgressions are documented here. We studied the sea retreat in the Tarim Basin in western China, the Alai Valley and Ferghana Basin in southern Kyrgyzstan and the Afghan-Tajik Basin in south-western Tajikistan. Integrated bio-magnetostratigraphic dating shows that the sea retreated westward from the Tarim Basin in stepwise fashion. The major fourth transgression occurred during the Lutetian, after which the sea retreated from the southwest Tarim Basin paleodepocenter at ~41 Ma (base C18r). The last and fifth transgression was restricted to the westernmost margin of the Tarim basin and occurred during latest Bartonian-early Priabonian (base C17n.3n-base C16n.1n). At the level of precision of our dating, each of these marine incursions is apparently synchronous across the Tarim Basin suggesting rapid regional transgression/regression cycles in these shallow epicontinental basins with limited diachroneity. The shallow marine near-shore sediments of these last two transgressions can be convincingly correlated by litho- and biostratigraphy across Central Asia, showing for the first time that the sea may have largely retreated from Central Asia in the late Eocene. The lack of apparent

  6. Beryllium-10 dating of the duration and retreat of the last pinedale glacial sequence.

    PubMed

    Gosse, J C; Klein, J; Lawn, B; Middleton, R; Evenson, E B

    1995-06-01

    Accurate terrestrial glacial chronologies are needed for comparison with the marine record to establish the dynamics of global climate change during transitions from glacial to interglacial regimes. Cosmogenic beryllium-10 measurements in the Wind River Range indicate that the last glacial maximum (marine oxygen isotope stage 2) was achieved there by 21,700 +/- 700 beryllium-10 years and lasted 5900 years. Ages of a sequence of recessional moraines and striated bedrock surfaces show that the initial deglaciation was rapid and that the entire glacial system retreated 33 kilometers to the cirque basin by 12,100 +/- 500 beryllium-10 years.

  7. Short-Interval Retreatment With Stereotactic Body Radiotherapy (SBRT) for Pediatric Neuroblastoma Resulting in Severe Myositis.

    PubMed

    Taunk, Neil K; Kushner, Brian; Ibanez, Katarzyna; Wolden, Suzanne L

    2016-04-01

    We report a severe and not previously reported toxicity after short-interval retreatment with stereotactic body radiotherapy (SBRT) in a pediatric patient with neuroblastoma. This patient experienced Grade III radiation myositis after treatment with conventional radiation therapy followed by high-dose SBRT for persistent disease a short interval after the initial radiotherapy course. While SBRT shows outstanding rates of local control in adult disease, data in pediatric cancers are extremely limited. In this report, we discuss the rationale of SBRT in this patient's multimodality neuroblastoma treatment, management of the toxicity, and future perspectives on the use of SBRT in pediatric cancer.

  8. Perception of approaching and retreating floor-projected shapes in a large, immersive, multimedia learning environment.

    PubMed

    Dolgov, Igor; Birchfield, David A; McBeath, Michael K; Thornburg, Harvey; Todd, Christopher G

    2009-04-01

    Perception of floor-projected moving geometric shapes was examined in the context of the Situated Multimedia Arts Learning Laboratory (SMALLab), an immersive, mixed-reality learning environment. As predicted, the projected destinations of shapes which retreated in depth (proximal origin) were judged significantly less accurately than those that approached (distal origin). Participants maintained similar magnitudes of error throughout the session, and no effect of practice was observed. Shape perception in an immersive multimedia environment is comparable to the real world. One may conclude that systematic exploration of basic psychological phenomena in novel mediated environments is integral to an understanding of human behavior in novel human-computer interaction architectures.

  9. Beryllium-10 dating of the duration and retreat of the last pinedale glacial sequence.

    PubMed

    Gosse, J C; Klein, J; Lawn, B; Middleton, R; Evenson, E B

    1995-06-01

    Accurate terrestrial glacial chronologies are needed for comparison with the marine record to establish the dynamics of global climate change during transitions from glacial to interglacial regimes. Cosmogenic beryllium-10 measurements in the Wind River Range indicate that the last glacial maximum (marine oxygen isotope stage 2) was achieved there by 21,700 +/- 700 beryllium-10 years and lasted 5900 years. Ages of a sequence of recessional moraines and striated bedrock surfaces show that the initial deglaciation was rapid and that the entire glacial system retreated 33 kilometers to the cirque basin by 12,100 +/- 500 beryllium-10 years. PMID:17778979

  10. Beryllium-10 dating of the duration and retreat of the last pinedale glacial sequence

    SciTech Connect

    Gosse, J.C. |; Klein, J.; Evenson, E.B.

    1995-06-02

    Accurate terrestrial glacial chronologies are needed for comparison with the marine record to establish the dynamics of global climate change during transitions from glacial to interglacial regimes. Cosmogenic beryllium-10 measurements in the Wind River Range indicate that the last glacial maximum (marine oxygen isotope stage 2) was achieved there by 21,700 {+-} 700 beryllium-10 years and lasted 5900 years. Ages of a sequence of recessional moraines and striated bedrock surfaces show that the initial deglaciation was rapid and that the entire glacial system retreated 33 kilometers to the cirque basin by 12,100 {+-} 500 beryllium-10 years.

  11. Endodontic retreatment of an autotransplanted lower first premolar: a case report.

    PubMed

    Koshy, Sajeev; Love, Robert Matthew

    2003-08-01

    A 24-year-old female with no contributory medical history had been treated by orthodontic alignment and transplantation of the lower left first premolar to the upper left first premolar site to correct for congenitally missing upper premolars. Subsequently, the transplanted premolar was treated by conventional endodontics and apical surgery for persistent periapical periodontitis over a span of 12 years. A combination of conventional endodontic retreatment and periapical surgery resulted in periapical healing. This case outlines the need for careful preoperative case assessment. PMID:12848718

  12. Boulder deposits and the retreat of mountain slopes, or ' gully gravure' revisited.

    USGS Publications Warehouse

    Mills, H.H.

    1981-01-01

    Observations on mountains composed chiefly of shale and capped with Tuscarora Sandstone in the Valley and Ridge province of southwest Virginia suggest that slopes retreat by a process similar to but different from Bryan's (1940) gulley gravure. This process probably is common wherever large resistant clasts are transported downslope over less resistant bedrock. Lateral migration of stream valleys has been shown to take place on mountain piedmonts under similar circumstances, but this study suggests that such migration may also take place on the upper slopes of mountains in hollows where water flow may be significant only a few times per century. -from Author

  13. Tectonic, lithologic and climatic controls on knickpoint retreat rates and landscape response times

    NASA Astrophysics Data System (ADS)

    Whittaker, Alexander; Boulton, Sarah; Kent, Emiko; Alçiçek, Cihat

    2016-04-01

    The plan-view and vertical rates at which transient knickpoints propagate through a landscape fundamentally controls geomorphic response times to tectonic and climatic perturbations. Here we present knickpoint retreat rates upstream of active faults for bedrock catchments in the Gediz graben of Turkey where past climate is well documented but where the history of faulting is not fully constrained. The rivers upstream of the normal fault-bounded graben each contain a non-lithologic knickpoint, including those that drain through inferred fault segment boundaries. Knickpoint heights measured vertically from the fault scale with footwall relief and documented fault throw (vertical displacement). Consequently, we deduce these knickpoints were initiated by an increase in slip rate on the basin-bounding fault, driven by linkage of the three main fault segments of the high-angle graben-bounding fault array. Fault interaction theory and ratios of channel steepness suggest that the slip rate enhancement factor on linkage was a factor of 3. We combine this information with geomorphic and structural constraints to estimate that linkage took place between 0.6 Ma and 1 Ma. Calculated pre- and post- linkage throw rates are 0.6 and 2 mm/yr respectively. Maximum plan-view knickpoint retreat rates upstream of the faults range from 4.5 to 28 mm/yr, and when normalised by drainage area, they are 2-7 times faster than for similar catchments upstream of normal faults in the Central Apennines of Italy and the Hatay Graben of Turkey. These knickpoint retreat rates imply a fluvial response time to fault growth and interaction of 1.6 to 2.7 My. However, marked along-strike disparities in retreat rates exist. We demonstrate that climate differences may explain the variation in rates between these study areas, but not within the Gediz graben itself. Consequently, we evaluate the extent to which measureable differences in bedrock lithology and erodibility modulate the propagation of

  14. Two-Day Curriculum Retreat: An Innovative Response to the Call for Reform.

    PubMed

    Lane, Adrianne J; Mitchell, Claudia G

    2015-01-01

    This article outlines processes followed during a two-day offsite retreat for nurse faculty planned for the purpose of curricular redesign and content mapping. Faculty identified and leveled content for all baccalaureate clinical courses and engaged in dialogue specific to promoting student connections between didactic and clinical outcomes. Faculty developed two core simulation scenarios for every clinical course and leveled learning outcomes for each. Faculty defined where within the curriculum key concepts were introduced and planned depth of knowledge, application, and synthesis from sophomore through senior levels. Evaluation revealed the process led faculty to a stronger overall understanding of the curriculum. PMID:26328298

  15. The Influence of Mining and Human Immunodeficiency Virus Infection Among Patients Admitted for Retreatment of Tuberculosis in Northern Tanzania.

    PubMed

    Mpagama, Stellah G; Lekule, Isaack A; Mbuya, Alexander W; Kisonga, Riziki M; Heysell, Scott K

    2015-08-01

    In tuberculosis (TB)-prevalent settings, patients admitted for retreatment of TB may account for a high burden of poor treatment outcome. We performed a retrospective cohort study to characterize retreatment patients and outcomes at a TB referral hospital in northern Tanzania. From 2009 to 2013, 185 patients began a retreatment regimen, the majority for relapse after prior treatment completion. Men accounted for an unexpected majority (88%), 36 (20%) were human immunodeficiency virus (HIV) infected and for 45 (24%) mining was their primary occupation. A poor outcome (death, default, or persistent smear positivity after 7 months of treatment) was found in 37 (23%). HIV infection was the only significant predictor of poor outcome (adjusted odds ratio [aOR] = 2.50, 95% confidence interval [CI] = 1.07-5.83, P = 0.034). Interventions to minimize need for retreatment or improve retreatment success may be regionally specific. In our setting, community-based diagnosis and management among at-risk subpopulations such as miners and those HIV infected appear of highest yield.

  16. The Influence of Mining and Human Immunodeficiency Virus Infection among Patients Admitted for Retreatment of Tuberculosis in Northern Tanzania

    PubMed Central

    Mpagama, Stellah G.; Lekule, Isaack A.; Mbuya, Alexander W.; Kisonga, Riziki M.; Heysell, Scott K.

    2015-01-01

    In tuberculosis (TB)–prevalent settings, patients admitted for retreatment of TB may account for a high burden of poor treatment outcome. We performed a retrospective cohort study to characterize retreatment patients and outcomes at a TB referral hospital in northern Tanzania. From 2009 to 2013, 185 patients began a retreatment regimen, the majority for relapse after prior treatment completion. Men accounted for an unexpected majority (88%), 36 (20%) were human immunodeficiency virus (HIV) infected and for 45 (24%) mining was their primary occupation. A poor outcome (death, default, or persistent smear positivity after 7 months of treatment) was found in 37 (23%). HIV infection was the only significant predictor of poor outcome (adjusted odds ratio [aOR] = 2.50, 95% confidence interval [CI] = 1.07–5.83, P = 0.034). Interventions to minimize need for retreatment or improve retreatment success may be regionally specific. In our setting, community-based diagnosis and management among at-risk subpopulations such as miners and those HIV infected appear of highest yield. PMID:26013368

  17. Observations beneath Pine Island Glacier in West Antarctica and implications for its retreat

    NASA Astrophysics Data System (ADS)

    Jenkins, Adrian; Dutrieux, Pierre; Jacobs, Stanley S.; McPhail, Stephen D.; Perrett, James R.; Webb, Andrew T.; White, David

    2010-07-01

    Thinning ice in West Antarctica, resulting from acceleration in the flow of outlet glaciers, is at present contributing about 10% of the observed rise in global sea level. Pine Island Glacier in particular has shown nearly continuous acceleration and thinning, throughout the short observational record. The floating ice shelf that forms where the glacier reaches the coast has been thinning rapidly, driven by changes in ocean heat transport beneath it. As a result, the line that separates grounded and floating ice has retreated inland. These events have been postulated as the cause for the inland thinning and acceleration. Here we report evidence gathered by an autonomous underwater vehicle operating beneath the ice shelf that Pine Island Glacier was recently grounded on a transverse ridge in the sea floor. Warm sea water now flows through a widening gap above the submarine ridge, rapidly melting the thick ice of the newly formed upstream half of the ice shelf. The present evolution of Pine Island Glacier is thus part of a longer-term trend that has moved the downstream limit of grounded ice inland by 30km, into water that is 300m deeper than over the ridge crest. The pace and ultimate extent of such potentially unstable retreat are central to the debate over the possibility of widespread ice-sheet collapse triggered by climate change.

  18. The future of ice sheets and sea ice: Between reversible retreat and unstoppable loss

    PubMed Central

    Notz, Dirk

    2009-01-01

    We discuss the existence of cryospheric “tipping points” in the Earth's climate system. Such critical thresholds have been suggested to exist for the disappearance of Arctic sea ice and the retreat of ice sheets: Once these ice masses have shrunk below an anticipated critical extent, the ice–albedo feedback might lead to the irreversible and unstoppable loss of the remaining ice. We here give an overview of our current understanding of such threshold behavior. By using conceptual arguments, we review the recent findings that such a tipping point probably does not exist for the loss of Arctic summer sea ice. Hence, in a cooler climate, sea ice could recover rapidly from the loss it has experienced in recent years. In addition, we discuss why this recent rapid retreat of Arctic summer sea ice might largely be a consequence of a slow shift in ice-thickness distribution, which will lead to strongly increased year-to-year variability of the Arctic summer sea-ice extent. This variability will render seasonal forecasts of the Arctic summer sea-ice extent increasingly difficult. We also discuss why, in contrast to Arctic summer sea ice, a tipping point is more likely to exist for the loss of the Greenland ice sheet and the West Antarctic ice sheet. PMID:19884496

  19. Nonsurgical endodontic retreatment of fused teeth with transposition: a case report

    PubMed Central

    Noites, Rita Brandão; Martins, Miguel André Duarte; Paulo, Manuel Pedro da Fonseca

    2016-01-01

    Tooth transposition is a disorder in which a permanent tooth develops and erupts in the normal position of another permanent tooth. Fusion and gemination are developmental disturbances presenting as the union of teeth. This article reports the nonsurgical retreatment of a very rare case of fused teeth with transposition. A patient was referred for endodontic treatment of her maxillary left first molar in the position of the first premolar, which was adjacent to it on the distobuccal side. Orthopantomography and periapical radiography showed two crowns sharing the same root, with a root canal treatment and an associated periapical lesion. Tooth fusion with transposition of a maxillary molar and a premolar was diagnosed. Nonsurgical endodontic retreatment was performed. At four yr follow-up, the tooth was asymptomatic and the radiolucency around the apical region had decreased, showing the success of our intervention. The diagnosis and treatment of fused teeth require special attention. The canal system should be carefully explored to obtain a full understanding of the anatomy, allowing it to be fully cleaned and obturated. Thermoplastic techniques were useful in obtaining hermetic obturation. A correct anatomical evaluation improves the set of treatment options under consideration, leading to a higher likelihood of esthetically and functionally successful treatment. PMID:27200284

  20. Using timing of ice retreat to predict timing of fall freeze-up in the Arctic

    NASA Astrophysics Data System (ADS)

    Stroeve, Julienne C.; Crawford, Alex D.; Stammerjohn, Sharon

    2016-06-01

    Reliable forecasts of the timing of sea ice advance are needed in order to reduce risks associated with operating in the Arctic as well as planning of human and environmental emergencies. This study investigates the use of a simple statistical model relating the timing of ice retreat to the timing of ice advance, taking advantage of the inherent predictive power supplied by the seasonal ice-albedo feedback and ocean heat uptake. Results show that using the last retreat date to predict the first advance date is applicable in some regions, such as Baffin Bay and the Laptev and East Siberian seas, where a predictive skill is found even after accounting for the long-term trend in both variables. Elsewhere, in the Arctic, there is some predictive skills depending on the year (e.g., Kara and Beaufort seas), but none in regions such as the Barents and Bering seas or the Sea of Okhotsk. While there is some suggestion that the relationship is strengthening over time, this may reflect that higher correlations are expected during periods when the underlying trend is strong.

  1. Retreat of northern margins of George VI and Wilkins Ice Shelves, Antarctic Peninsula

    USGS Publications Warehouse

    Lucchitta, B.K.; Rosanova, C.E.

    1998-01-01

    The George VI and Wilkins Ice Shelves are considered at risk of disintegration due to a regional atmospheric warming trend on the Antarctic Peninsula. Retreat of the northern margin of the George VI Ice Shelf has been observed previously, but the Wilkins Ice Shelf was thought to be stable. We investigated the positions of the northern fronts of these shelves from the literature and looked for changes on 1974 Landsat and 1992 and 1995 European remote-sensing satellite (ERS) synthetic aperture radar images. Our investigation shows that the northern George VI Ice Shelf lost a total of 906 km2 between 1974 and 1992, and an additional 87 km2 by 1995. The northern margin of the Wilkins Ice Shelf lost 796 km2 between 1990 and 1992, and another 564 km2 between 1992 and 1995. Armadas of tabular icebergs were visible in front of this shelf in the ERS images. These two ice shelves mark the southernmost documented conspicuous retreat of ice-shelf margins.

  2. Coastal retreat and shoreface profile variations in the Canadian Beaufort Sea

    USGS Publications Warehouse

    Hequette, A.; Barnes, P.W.

    1990-01-01

    The coastline of the southern Canadian Beaufort Sea consists primarily of unconsolidated bluffs. Although the sea is ice-free for 3 months of the year and wave energy is restricted by pack ice, the coast is undergoing regional retreat with erosion rates as high as 10 m a-1 in some locations. Simple and multiple regression analyses were carried out to determine the degree of correlation between the mean retreat rate measured at various locations and the different parameters that may control shoreline recession. Sediment texture, ground-ice content, cliff height, wave energy and shoreface gradient revealed medium to poor correlation with erosion rates, showing that the recessive evolution of the coastline can not be explained solely by wave-induced and subaerial processes. The comparison of nearshore echo-sounding records from 1987 with bathymetry from 1971 showed substantial erosion (up to 1 m) of the submarine profile between 12 and 15 m of water. There is strong evidence that this erosion has been caused by sea ice gouging on the seafloor. From depths of 5 to 9 m, accretion has taken place, possibly induced by ice-push processes, and inshore of the 5 m isobath wave and current erosion of the shoreface has occurred. These results suggest that the erosion of the inner shelf by ice gouging drives the erosion observed inshore on the coastal bluffs and nearshore zone as the shoreface profile strives for a state of dynamic equilibrium. ?? 1990.

  3. In vitro infrared thermographic assessment of root surface temperature rises during thermafil retreatment using system B.

    PubMed

    Lipski, Mariusz; Woźniak, Krzysztof

    2003-06-01

    The purpose of this in vitro study was to measure the temperature rise on the outer root surface during retreatment of Thermafil using the System B HeatSource. Twenty extracted human maxillary premolars were filled with Thermafil with plastic carriers and divided into two groups of 10 teeth each. In group 1, Thermafil obturators were retrieved using System B HeatSource fitted with a medium plugger at a temperature of 225 degrees C. The plugger was placed first on the buccal, then on the lingual of the plastic carrier for 5 s each. This melted the gutta-percha and softened the plastic carrier. In group 2, Thermafil obturators were retrieved in the same manner except that the heated plugger was placed for 8 s. The temperature changes on the outer root surfaces were recorded using a thermal imaging camera. Thermafil retreatment in vitro using a System B HeatSource causes temperature rises ranging from 26.7 degrees C to 46.0 degrees C. This finding could possibly have implications for creating injury of the periodontal tissues.

  4. Apical extrusion of debris by supplementary files used for retreatment: An ex vivo comparative study

    PubMed Central

    Pawar, Ajinkya M.; Pawar, Mansing; Metzger, Zvi; Thakur, Bhagyashree

    2016-01-01

    Aim: This study evaluated whether using supplementary files for removing root canal filling residues after ProTaper Universal Retreatment files (RFs) increased the debris extrusion apically. Materials and Methods: Eighty mandibular premolars with single root and canal were instrumented with ProTaper Universal rotary system (SX-F3) and obturated. The samples were divided randomly into four groups (n = 20). Group 1 served as a control; only ProTaper Universal RFs D1–D3 were used, and the extruded debris was weighed. Groups 2, 3, and 4 were the experimental groups, receiving a twofold retreatment protocol: Removal of the bulk, followed by the use of supplementary files. The bulk was removed by RFs, followed by the use of ProTaper NEXT (PTN), WaveOne (WO), and Self-Adjusting File (SAF) for removal of the remaining root filling residues. Debris extruded apically were weighed and compared to the control group. Statistical analysis was performed using one-way analysis of variance (ANOVA) and post hoc Tukey's test. Results: All the three experimental groups presented significant difference (P < .01). The post hoc Tukey's test confirmed that Group 4 (SAF) exhibited significantly less (P < .01) debris extrusion between the three groups tested. Conclusion: SAF results in less extrusion of debris when used as supplementary file to remove root-filling residues, compared to WO and PTN. PMID:27099416

  5. ACR Appropriateness Criteria Retreatment of Recurrent Head and Neck Cancer After Prior Definitive Radiation

    SciTech Connect

    McDonald, Mark W.; Lawson, Joshua; Garg, Madhur Kumar; Quon, Harry; Ridge, John A.; Saba, Nabil; Salama, Joseph K.; Smith, Richard V.; Yeung, Anamaria Reyna; Yom, Sue S.; Beitler, Jonathan J.

    2011-08-01

    Recurrent and second primary head-and-neck squamous cell carcinomas arising within or in close proximity to previously irradiated fields are a common clinical challenge. Whereas surgical salvage therapy is recommended for resectable disease, randomized data support the role of postoperative reirradiation in high-risk patients. Definitive reirradiation is an established approach for patients with recurrent disease who are medically or technically inoperable or decline radical surgery. The American College of Radiology Expert Panel on Head and Neck Cancer reviewed the relevant literature addressing re-treatment after prior definitive radiation and developed appropriateness criteria for representative clinical scenarios. Examples of unresectable recurrent disease and microscopic residual disease after salvage surgery were addressed. The panel evaluated the appropriateness of reirradiation, the integration of concurrent chemotherapy, radiation technique, treatment volume, dose, and fractionation. The panel emphasized the importance of patient selection and recommended evaluation and treatment at tertiary-care centers with a head-and-neck oncology team equipped with the resources and experience to manage the complexities and toxicities of re-treatment.

  6. Signatures of sea level changes on tidal geomorphology: Experiments on network incision and retreat

    NASA Astrophysics Data System (ADS)

    Stefanon, Luana; Carniello, Luca; D'Alpaos, Andrea; Rinaldo, Andrea

    2012-06-01

    How do tidal networks respond to changes in relative mean sea level (RMSL)? The question on whether the morphological features of a tidal landscape retain signatures of past environmental forcings, or are in equilibrium with current ones, is critical to our prediction of the fate of residual tidal landforms. In the case of tidal networks, the issue is quite relevant owing to their fundamental role on landscape eco-morphodynamic evolution. Here we explore the response of tidal networks to cyclic variations in RMSL triggering tidal prism changes on the basis of laboratory experiments carried out in a synthetic lagoonal environment. A decrease in the tidal prism leads to network retreat and contraction of channel cross sections. Conversely, an increase in the tidal prism promotes network re-incision and re-expansion of channel cross sections: Network retreat and expansion tend to occur within the same planar blueprint. Our results show that the drainage density of tidal channels is linearly related to the landscape-forming prism, although this relation is speculated to hold with reasonable approximation as a statistical tendency rather than as a pointwise, instantaneous adaptation. Changes in tidal prism rapidly influence network efficiency in draining the intertidal platform and the related transport of water, sediments, nutrients and pollutants. This bears important consequences for quantitative predictions of the long-term ecomorphological adaptation of the tidal landscape to RMSL changes.

  7. Nonsurgical endodontic retreatment of fused teeth with transposition: a case report.

    PubMed

    Cardoso, Miguel Agostinho Beco Pinto; Noites, Rita Brandão; Martins, Miguel André Duarte; Paulo, Manuel Pedro da Fonseca

    2016-05-01

    Tooth transposition is a disorder in which a permanent tooth develops and erupts in the normal position of another permanent tooth. Fusion and gemination are developmental disturbances presenting as the union of teeth. This article reports the nonsurgical retreatment of a very rare case of fused teeth with transposition. A patient was referred for endodontic treatment of her maxillary left first molar in the position of the first premolar, which was adjacent to it on the distobuccal side. Orthopantomography and periapical radiography showed two crowns sharing the same root, with a root canal treatment and an associated periapical lesion. Tooth fusion with transposition of a maxillary molar and a premolar was diagnosed. Nonsurgical endodontic retreatment was performed. At four yr follow-up, the tooth was asymptomatic and the radiolucency around the apical region had decreased, showing the success of our intervention. The diagnosis and treatment of fused teeth require special attention. The canal system should be carefully explored to obtain a full understanding of the anatomy, allowing it to be fully cleaned and obturated. Thermoplastic techniques were useful in obtaining hermetic obturation. A correct anatomical evaluation improves the set of treatment options under consideration, leading to a higher likelihood of esthetically and functionally successful treatment. PMID:27200284

  8. Committed near-future retreat of Smith, Pope, and Kohler Glaciers inferred by transient model calibration

    NASA Astrophysics Data System (ADS)

    Goldberg, D.; Heimbach, P.; Joughin, I.; Smith, B.

    2015-08-01

    A glacial flow model of Smith, Pope and Kohler Glaciers has been calibrated by means of inverse methods against time-varying, annualy resolved observations of ice height and velocities, covering the period 2002 to 2011. The inversion - termed "transient calibration" - produces an optimal set of time-mean, spatially varying parameters together with a time-evolving state that accounts for the transient nature of observations and the model dynamics. Serving as an optimal initial condition, the estimated state for 2011 is used, with no additional forcing, for predicting grounded ice volume loss and grounding line retreat over the ensuing 30 years. The transiently calibrated model predicts a near-steady loss of grounded ice volume of approximately 21 km3 a-1 over this period, as well as loss of 33 km2 a-1 grounded area. We contrast this prediction with one obtained following a commonly used "snapshot" or steady-state inversion, which does not consider time dependence and assumes all observations to be contemporaneous. Transient calibration is shown to achieve a better fit with observations of thinning and grounding line retreat histories, and yields a quantitatively different projection with respect to ice volume loss and ungrounding. Sensitivity studies suggest large near-future levels of unforced, i.e. committed sea level contribution from these ice streams under reasonable assumptions regarding uncertainties of the unknown parameters.

  9. Committed near-future retreat of Smith, Pope, and Kohler Glaciers inferred by transient model calibration

    NASA Astrophysics Data System (ADS)

    Goldberg, D. N.; Heimbach, P.; Joughin, I.; Smith, B.

    2015-12-01

    A glacial flow model of Smith, Pope and Kohler Glaciers has been calibrated by means of inverse methods against time-varying, annualy resolved observations of ice height and velocities, covering the period 2002 to 2011. The inversion -- termed ``transient calibration'' -- produces an optimal set of time-mean, spatially varying parameters together with a time-evolving state that accounts for the transient nature of observations and the model dynamics. Serving as an optimal initial condition, the estimated state for 2011 is used, with no additional forcing, for predicting grounded ice volume loss and grounding line retreat over the ensuing 30 years. The transiently calibrated model predicts a near-steady loss of grounded ice volume of approximately 21 km3/a over this period, as well as loss of 33 km2/a grounded area. We contrast this prediction with one obtained following a commonly used ``snapshot'' or steady-state inversion, which does not consider time dependence and assumes all observations to be contemporaneous. Transient calibration is shown to achieve a better fit with observations of thinning and grounding line retreat histories, and yields a quantitatively different projection with respect to ice volume loss and ungrounding. Sensitivity studies suggest large near-future levels of unforced, i.e. committed sea level contribution from these ice streams under reasonable assumptions regarding uncertainties of the unknown parameters.

  10. Late effects of radiation on the lumbar spinal cord of guinea pigs: Re-treatment tolerance

    SciTech Connect

    Mason, K.A. ); Withers, H.R.; Chiang, Chi-Shiun )

    1993-07-15

    Using a guinea pig model of lumbar myelopathy, various factors affecting the tolerance of spinal cord to irradiation were assessed: (a) extent of initial injury; (b) time interval between priming and test doses; and (c) animal age at the time of initial radiation treatment. A 3 cm section of lumbar spinal cord of guinea pigs was irradiated with fractionated doses of 4.5 Gy gamma rays given as 9 fractions per week. Guinea pigs were primed with 9 x 4.5 Gy in 7 days which is 60% of the ED[sub 50] for a continuous course of treatment. After 28 or 40 weeks, animal were retreated with 6-14 fractions of 4.5 Gy. Animals were observed for 2 years following the priming dose and both the incidence and latency of myelopathy recorded. Young adult guinea pigs (8 wk old) showed both a decreased radiation tolerance and latency compared to old individuals (40 wk old). At 28 or 40 wk after 9 x 4.5 Gy, only about 8% of the initial injury was remembered in young adult guinea pigs. The amount of residual injury was dependent on the initial damage as a proportion of the tolerance dose. The spinal cord shows a greater capacity for long-term recovery than generally appreciated and re-treatment doses clinically prescribed may be lower than necessary. 8 refs., 3 figs., 2 tabs.

  11. Treatment outcome in endodontics: the Toronto study--phases 3 and 4: orthograde retreatment.

    PubMed

    de Chevigny, Cristian; Dao, Thuan T; Basrani, Bettina R; Marquis, Vincent; Farzaneh, Mahsa; Abitbol, Sarah; Friedman, Shimon

    2008-02-01

    Outcome 4-6 years after retreatment was assessed for Phases 3 and 4 of the Toronto Study. Of 477 teeth retreated, 333 were lost to follow-up, 18 were extracted, and 126 (41% recall, excluding 124 discontinuers) were examined for outcome of healed (periapical index score, < or = 2; no signs or symptoms) or diseased. When pooled with Phases 1 and 2, 187 of 229 teeth (82%) were healed. Logistic regression identified significant (P < or = .05) preoperative outcome predictors: root filling quality (odds ratio [OR], 4.18; confidence interval [CI], 1.72-10.12; healed: inadequate, 88%; adequate, 66%), perforation (OR, 4.01; CI, 1.28-12.62; healed: absent, 87%; present, 56%), and radiolucency (OR, 3.33; CI, 1.19-9.36; healed: absent, 93%; present, 80%). In teeth with radiolucency, outcome predictors were number of treatment sessions (OR, 12.08; CI, 1.84-infinity; healed: one, 100%; > or = 2, 77%) and previous root filling quality (OR, 7.68; CI, 2.36-26.89; healed: inadequate, 86%; adequate, 50%). Outcome was better in teeth with inadequate previous root filling, without perforation and radiolucency. Suggested significance of number of treatment sessions in teeth with radiolucency requires validation from randomized controlled trials.

  12. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, B.E.; Miller, J.L.; Ault, E.R.

    1994-08-23

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window. 2 figs.

  13. Longitudinal discharge laser baffles

    DOEpatents

    Warner, B.E.; Ault, E.R.

    1994-06-07

    The IR baffles placed between the window and the electrode of a longitudinal discharge laser improve laser performance by intercepting off-axis IR radiation from the laser and in doing so reduce window heating and subsequent optical distortion of the laser beam. 1 fig.

  14. Longitudinal discharge laser baffles

    DOEpatents

    Warner, Bruce E.; Ault, Earl R.

    1994-01-01

    The IR baffles placed between the window and the electrode of a longitudinal discharge laser improve laser performance by intercepting off-axis IR radiation from the laser and in doing so reduce window heating and subsequent optical distortion of the laser beam.

  15. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, Bruce E.; Miller, John L.; Ault, Earl R.

    1994-01-01

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window.

  16. Short-term variability in the dates of the Indian monsoon onset and retreat on the southern and northern slopes of the central Himalayas as determined by precipitation stable isotopes

    NASA Astrophysics Data System (ADS)

    Yu, Wusheng; Yao, Tandong; Tian, Lide; Ma, Yaoming; Wen, Rong; Devkota, Lochan P.; Wang, Weicai; Qu, Dongmei; Chhetri, Tek B.

    2016-07-01

    This project launched the first study to compare the stable isotopes (δ18O and δD) in daily precipitation at Kathmandu (located on the southern slope of the central Himalayas) and Tingri (located on the northern slope). The results show that low δ18O and δD values of summer precipitation at the two stations were closely related to intense convection of the Indian monsoon. However, summer δ18O and δD values at Tingri were lower than those at Kathmandu, a result of the lift effect of the Himalayas, coupled with convection disturbances and lower temperatures at Tingri. In winter, the relatively high δ18O and δD values at the two stations appears to have resulted from the influence of the westerlies. Compared with those during the summer, the subsidence of the westerlies and northerly winds resulted in relatively high δ18O and δD values of the winter precipitation at Tingri. Winter δ18O and δD values at Kathmandu far exceeded those at Tingri, due to more intense advection of the southern branch of the westerlies, and higher temperatures and relative humidity at Kathmandu. The detailed differences in stable isotopes between the two stations follow short-term variability in the onset date of the Indian monsoon and its retreat across the central Himalayas. During the sampling period, the Indian monsoon onset at Tingri occurred approximately 1 week later than that at Kathmandu. However, the retreat at Tingri began roughly 3 days earlier. Clearly, the duration of the Indian monsoon effects last longer at Kathmandu than that at Tingri. Our findings also indicate that the India monsoon travels slowly northward across the central Himalayas due to the blocking of the Himalayas, but retreats quickly.

  17. Comparison of Endodontic Retreatment in Teeth Obturated With Resilon or Gutta-Percha: A Review of Literature

    PubMed Central

    Soares, Ciro; Maia, Conceição; Vale, Fábio; Gadê-Neto, Cícero; Carvalho, Lilian; Oliveira, Hanieri; Carvalho, Rejane

    2015-01-01

    Introduction: Retreatment of endodontically treated teeth is a challenge that requires complete removal of the previous filling material. Several techniques are indicated for this procedure. The present review tries to identify the most efficient method for extirpation of Resilon (RS) root fillings and to compare the speed and efficacy of RS and gutta-percha (GP) root filling removal. Methods and Materials: Three trained evaluators conducted a search through three major databases (PubMed, Cochrane Library and Lilacs) over the articles published in the period from 2001 to 2014. The search keywords were Epiphany Sealer, Resilon, Retreatment and Removal Procedure. Results: Twelve articles were included in the final sample (three in vitro studies and nine randomized trials). Conclusion: The ProTaper (manual or rotatory) system in combination with chemical solvents is the most efficient method for removing Resilon root filling. Retreatment of Resilon is more rapid and associated with less remnants of debris. PMID:26523136

  18. National Assessment of Historical Shoreline Change: A Pilot Study of Historical Coastal Bluff Retreat in the Great Lakes, Erie, Pennsylvania

    USGS Publications Warehouse

    Hapke, Cheryl J.; Malone, Shamus; Kratzmann, Meredith G.

    2009-01-01

    Coastal bluff retreat is a chronic problem along many high-relief coastlines in the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regard-ing trends and rates of bluff retreat. There is also a need for a comprehensive analysis that is consistent from one coastal region to another. To address these national needs, the U.S. Geological Survey (USGS), as part of the National Assessment of Coastal Change Hazards Project, conducted a pilot study of bluff retreat along the Lake Erie, Pa., coastline to assess the feasibility of undertaking a larger, multi-state analysis in the Great Lakes region. This report provides an overview of the pilot-study location and bluff geomorphology, the data sources and methodology, results of the analysis, and a discussion of the feasibility of undertaking a similar analysis along eroding bluffs in other Great Lakes states. This pilot study is part of an ongoing effort by the USGS to provide a comprehensive analysis of historical shoreline change and cliff and bluff retreat along open-ocean coastlines of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of the work is to develop standard, repeatable methods for mapping and analyzing coastal change so that systematic and consistent periodic updates of coastal erosion can be made nationally. Bluff-retreat evaluations are conducted by comparing the location of a historical bluff edge digitized from aerial photographs with those of recent bluff edges interpreted from both aerial photographs and lidar topographic surveys. The historical bluff edge is from 1938, whereas the more recent bluff edges are from 1998 and 2006 lidar data. Long-term (68-year) rates of retreat are calculated using the available bluff-edge data. The rates of retreat presented in this report represent conditions from the 1930s to 1998/2006, and are not intended for

  19. Penetrability of AH plus and MTA fillapex after endodontic treatment and retreatment: a confocal laser scanning microscopy study.

    PubMed

    Kok, Daniela; Rosa, Ricardo Abreu da; Barreto, Mirela Sangoi; Busanello, Fernanda Hoffmann; Santini, Manuela Favarin; Pereira, Jefferson Ricardo; Só, Marcus Vinícius Reis

    2014-06-01

    The aim of the study was to assess the penetrability of two endodontic sealers (AH Plus and MTA Fillapex) into dentinal tubules, submitted to endodontic treatment and subsequently to endodontic retreatment. Thirty ex vivo incisors were prepared using ProTaper rotary system up to F3 instrument and divided in three groups according to the endodontic sealer used for root canal filling: AH Plus (AHP), MTA Fillapex (MTAF), and control group (CG) without using EDTA previously to the root canal filling. Rhodamine B dye (red) was incorporated to the sealers in order to provide the fluorescence which will enable confocal laser scanning microscopy (CLSM) assessment. All specimens were filled with gutta-percha cones using the lateral compaction technique. The specimens were submitted to endodontic retreatment using ProTaper Retreatment system, re-prepared up to F5 instruments and filled with gutta-percha cones and the same sealer used during endodontic retreatment. Fluorescein dye (green) was incorporated to the sealer in order to distinguish from the first filling. The roots were sectioned 2 mm from the apex and assessed by CLSM. No difference was found between the two experimental groups (P > 0.05). On the other hand, in the control group the sealers were not capable to penetrate into dentinal tubules after endodontic treatment (P > 0.05). In retreatment cases, none of the sealers were able to penetrate into dentin tubules. It can be concluded that sealer penetrability is high during endodontic treatment. However, MTA Fillapex and AH Plus do not penetrate into dentinal tubules after endodontic retreatment.

  20. Observations of historical sea cliff retreat rates exceed long-term estimates derived from cosmogenic 10Be

    NASA Astrophysics Data System (ADS)

    Hurst, Martin D.; Rood, Dylan H.; Ellis, Michael A.; Anderson, Robert S.

    2015-04-01

    Historical observation of coastal retreat are limited to relatively short timescales (< 150 years), during which time humans may have modified the coastal environment. There is growing concern that rates of coastal change may be accelerated in the face of anticipated stormier climates and rising sea level, yet there is little knowledge of rates of coastal change prior to the relatively brief historical records. In order to make predictions about potential future coastal change it is important to establish baseline conditions averaged over longer time periods. Here we present analysis of sea cliff retreat throughout the Holocene averaged for chalk cliffs in south-east England using cosmogenic isotopes. We determine long-term rates of sea cliff erosion from 10Be measured from in-situ flint samples collected from three transects across coastal platforms in East Sussex. A numerical model of 10Be accumulation on an evolving coastal profile allows estimation of cliff retreat rate during the Holocene. The model accounts for variation in 10Be accumulation with tides and sea-level rise, and takes into account platform downwear and topographic shielding by adjacent cliffs. We find that cliff retreat rates during the Holocene were significantly slower (2-6 cm yr-1) than those derived from recent historical observations (15-25 cm yr-1). Modelled accumulation of 10Be requires retreat rates that increase rapidly in recent times, potentially reflecting human modification of the coastal sediment budget through construction of sea defences, flood defenses and aggregate extraction. Therefore knowledge of past human activity at the coastline may be important in anticipating future rates of coastal retreat.

  1. Inference for longitudinal data with nonignorable nonmonotone missing responses

    PubMed Central

    Sinha, Sanjoy K.; Kaushal, Amit; Xiao, Wenzhong

    2014-01-01

    For the analysis of longitudinal data with nonignorable and nonmonotone missing responses, a full likelihood method often requires intensive computation, especially when there are many follow-up times. The authors propose and explore a Monte Carlo method, based on importance sampling, for approximating the maximum likelihood estimators. The finite-sample properties of the proposed estimators are studied using simulations. An application of the proposed method is also provided using longitudinal data on peptide intensities obtained from a proteomics experiment of trauma patients. PMID:25435599

  2. Modeling HIF relevant longitudinal dynamics in UMER

    NASA Astrophysics Data System (ADS)

    Beaudoin, B. L.; Bernal, S.; Blanco, C.; Haber, I.; Kishek, R. A.; Koeth, T.; Mo, Y.

    2014-01-01

    The foremost challenge for Heavy-Ion Fusion (HIF) is achieving sufficiently low emittances and small energy spreads in the presence of intense space-charge, to achieve the high deposition densities necessary for pellet ignition. The University of Maryland Electron Ring (UMER) uses intense low-energy electron beams to access the scaled physics of HIF drivers. In particular, the long path-length propagation in UMER presents an opportunity to study, at realistic scales, the longitudinal beam dynamics and manipulations required for such a driver. With the use of induction modules, as in the ion machines such as NDCX-II, the resulting bunch dynamics show evidence of space-charge waves excited by an initial mismatch between the detailed initial beam distribution at the bunch ends and the applied focusing waveforms, persisting with multiple damped reflections propagating along the bunch flat-top. Using the induction module we are able to suppress space-charge waves with great accuracy, at amplitudes that include wave steepening prior to the formation of solitary wave trains. The longitudinal dynamics largely dominates when no containment fields are applied, coupling through the natural chromaticity of the ring even within the first turn. After subsequent turns, the bunch elongates and wraps the circumference of the machine multiple times; eventually reaching a point of instability that has also been shown through simulation, obtaining excellent agreement when the detailed longitudinal dynamics of the experiment are carefully incorporated into the model.

  3. Evaluation of the bank stability and toe erosion model (BSTEM) for predicting lateral retreat on composite streambanks

    NASA Astrophysics Data System (ADS)

    Midgley, Taber L.; Fox, Garey A.; Heeren, Derek M.

    2012-04-01

    Streambank erosion is known to be a major source of sediment in streams and rivers. The Bank Stability and Toe Erosion Model (BSTEM) was developed in order to predict streambank retreat due to both fluvial erosion and geotechnical failure. However, few, if any, model evaluations using long-term streambank retreat data have been performed. The objectives of this research were to (1) monitor long-term composite streambank retreat during a hydraulically active period on a rapidly migrating stream, (2) evaluate BSTEM's ability to predict the measured streambank retreat, and (3) assess the importance of accurate geotechnical, fluvial erosion, and near-bank pore-water pressure properties. The Barren Fork Creek in northeastern Oklahoma laterally eroded 7.8 to 20.9 m along a 100-m length of stream between April and October 2009 based on regular bank location surveys. The most significant lateral retreat occurred in mid- to late-May and September due to a series of storm events, and not necessarily the most extreme events observed during the monitoring period. BSTEM (version 5.2) was not originally programmed to run multiple hydrographs iteratively, so a subroutine was written that automatically input the temporal sequence of stream stage and to lag the water table in the near-bank ground water depending on user settings. Eight BSTEM simulations of the Barren Fork Creek streambank were performed using combinations of the following input data: with and without a water table lag; default BSTEM geotechnical parameters (moderate silt loam) versus laboratory measured geotechnical parameters based on direct shear tests on saturated soil samples; and default BSTEM fluvial erosion parameters versus field measured fluvial erosion parameters from submerged jet tests. Using default BSTEM input values underestimated the actual erosion that occurred. Lagging the water table predicted more geotechnical failures resulting in greater streambank retreat. Using measured fluvial and

  4. Efficacy of Different Methods for Removing Root Canal Filling Material in Retreatment - An In-vitro Study

    PubMed Central

    Mariswamy, Annapoorna Ballagere

    2016-01-01

    Introduction Although success of endodontic therapy has significantly improved in the last few decades due to the introduction of novel materials and techniques, failures of endodontic therapy requiring re-treatment still comprise a significant percentage of patients requiring root canal treatment. Aim To evaluate and compare the effective removal of gutta percha and sealer, amount of apical debris extrusion and time required for gutta percha removal using various endodontic files. Materials and Methods Total 48 extracted mandibular premolars were mounted on acrylic blocks and endodontic procedure was carried out using size 40 K file and obturated using guttapercha and zinc oxide eugenol sealer. After one month storage, samples were decoronated, mounted on screw capped vials and subjected to removal of obturated material by four instruments: H files, safe sided H files, protaper universal retreatment rotary system and ultrasonic retreatment tip, grouped as 1, 2, 3, and 4 respectively. Only 2mm of obturated material from the coronal part was removed using no. 3 Gates Glidden drill, guttapercha was softened with a drop of xylene for 2 mins for each canal and retreatment was performed. The retreatment procedure was said to be complete when no visible debris were observed on the instrument flutes. The samples split into two halves and examined under stereomicroscope, photographed, assessed using AUTOCAD software and percentage of remaining filling material in coronal, middle, apical thirds of the canal was calculated in mm2. Retreatment time was recorded in seconds and apically extruded debris was assessed by microbalance in grams for each tooth. The data was analyzed by using descriptive statistics, ANOVA and Scheffe’s post hoc test through SPSS for windows (v 16.0). Results The ultrasonic retreatment tip had less percentage of residual guttapercha/sealer, shorter mean operating time and little apical extrusion with a significant difference (p<0.05) between the

  5. Estimating Glacier Retreat through Satellite Based Observation In the Beas Basin, Himachal Pradesh, India

    NASA Astrophysics Data System (ADS)

    Dutta, Shruti; Ramanathan, Al.; Linda, Anurag

    2010-05-01

    Glaciers are now well recognized as the most reliable indicators of climate (IPCC, 2007), more particularly in the regions where there is an acute paucity in the availability of meteorological database. Subsequently it can be said that monitoring the glaciers is important to assess the overall reservoir health (Kulkarni et al., 2007). Almost negligible studies have been conducted to investigate the deglaciation status in the Indian Himalaya. A change detection analysis of the areal cover of glaciers in the Beas basin, India with the aid of remote sensing techniques in the present study concludes that the Beas basin has witnessed a loss of about 22.49 km2in the last four decades which is about 22% of the area. Another major aspect of this study is the noticeable retreat of the glaciers in the period 1972-1989. The glaciers in the Beas basin show larger area loss in this period as compared to the loss in area during the 1990s and later. Thus, it can be said that in spite of the alarming scenario of a continued recession of the glaciated terrain in the Beas basin, the pace of retreat has been observed to slow down after the 1990s. The loss has been more significant in the glaciers comprising of the area of 2-5 km2range as compared to the other categories. Glaciers in the area range more than 5 km2and less than 2 km2show less variation reflecting not much of significant loss. The total number of glaciers increased in the period of last four decades although not very significantly, indicating fragmentation. The glaciers in the range 0.5-2 km2 show a higher tendency towards fragmentation. The average elevation of the glaciers in the basin underwent an upward shift from 4565 m in the year 1972 to 4629 m in the year 2006 which is a reason for concern. The gradual upward shifting of contours over a period of almost four decades can be a consequence of a shift in Equilibrium Line Altitude (ELA) which has been constantly moving upwards showing a retreat of glaciers in the

  6. Modeling the rate and style of Arctic coastal retreat along the Beaufort Sea, Alaska

    NASA Astrophysics Data System (ADS)

    Barnhart, K. R.; Anderson, R. S.; Overeem, I.; Wobus, C. W.; Clow, G. D.; Urban, F. E.; Stanton, T. P.

    2010-12-01

    In Arctic landscapes, modern surface warming has significantly altered geomorphic process rates. Along the Beaufort Sea coastline bounding Alaska’s North Slope, the mean annual coastal erosion rate has doubled from ~7 m/yr for 1955-1979 to ~14 m/yr for 2002-2007 (Mars and Houseknecht, 2007). Locally the erosion rate can reach 30 m/yr, with short-term rates that are far greater than this. A robust understanding of the processes that govern the rate of coastal erosion is required in order to predict the response of the coast and its adjacent landscape to a rapidly changing climate, with implications for sediment and carbon fluxes, oilfield infrastructure, and animal habitat. Constrained by time-lapse imagery, and by measurements of both the oceanic and atmospheric conditions, we have developed a numerical model to capture the evolution of the permafrost bluffs on the North Slope. During the sea ice-free season, relatively warm waters melt a notch into the ice-rich silt that comprises the 4-m tall bluffs. The bluffs ultimately fail by toppling of polygonal blocks bounded by mechanically weak ice-wedges that are spaced roughly 10-20 m apart. The toppled blocks then temporarily armor the coast against further attack. The annual retreat rate is controlled by the length of the sea ice-free season, water and air temperatures, and the wave history. Honoring the high ice content of the bluff materials, we employ a positive degree day algorithm to govern subaerial melt, and an iceberg melting algorithm to determine rate of notch incision. In the iceberg melting algorithm, the local instantaneous melt rate goes as the product of the temperature difference between seawater and bluff material, the sea state, captured by the ratio of wave height to wave period, and the ratio of ice surface roughness to wave height to the 0.2 power (Kubat et al., 2007). The calculated instantaneous melt rate is adjusted to account for the ambient temperature of the permafrost and the presence of

  7. Estimating the timescale of the seawater retreat in coastal aquifers: Dimensional analysis and numerical investigations

    NASA Astrophysics Data System (ADS)

    Mamalakis, Antonios; Kaleris, Vassilios; Dimas, Athanassios

    2016-04-01

    Submarine groundwater discharge (SGD) constitutes an important source of contaminants to the coastal ocean. Large fluxes of SGD are related to the retreat of the freshwater-saltwater interface, occurring during the period of the year, when the groundwater levels in the aquifer are high (usually in spring or summer). The estimation of the groundwater fluxes discharging to the coastal ocean as well as the timescale of the process are of crucial importance, since they are related to the actual chemical loading of the coastal waters during the swimming period. For the investigation of groundwater hydraulics in the coastal area, both analytical and numerical methods have been presented in the literature. The former are usually based on simplifying approximations which assume that (a) the freshwater and the saltwater are immiscible fluids (sharp interface approach) and (b) the pressure distribution in the freshwater area is hydrostatic and the saltwater is stationary (Gyben-Herzberg assumption). However, such solutions mainly concern steady state problems with simple geometrical and geological conditions, without accounting for the temporal component of each phenomenon. Numerical models which take into consideration the mixing between saltwater and fresh water, allow for more complete analysis of complicated problems, however, they require considerable computational effort. In this study we present a simple finite differences model based on the sharp interface approach, which is used in order to investigate the dynamics of the SGD in periods when the freshwater-saltwater interface is in retreat and the rate of SGD is large. The reliability of the model is investigated by performing sensitivity analysis of the simulation results relatively to the spatial and temporal discretization. The purpose of our simulations is to derive simple relationships that allow estimation of (a) the timescale of seawater retreat phenomena and (b) the magnitude of the SGD-rates, as function of

  8. The cycle of instability: stress release and fissure flow as controls on gully head retreat

    NASA Astrophysics Data System (ADS)

    Collison, A. J. C.

    2001-01-01

    Gully head and wall retreat has commonly been attributed to fluvial scour and head collapse as a result of soil saturation, sapping or piping. The empirical evidence to substantiate these conceptual models is sparse, however, and often contradictory. This paper explores the hydrological and mechanical controls on gully head and wall stability by modelling the hydrology, stability and elastic deformation of a marl gully complex in Granada Province, south-east Spain. The hydrological and slope-stability simulations show that saturated conditions can be reached only where preferential fissure flow channels water from tension cracks into the base of the gully head, and that vertical or subvertical heads will be stable unless saturation is achieved. Owing to the high unsaturated strengths of marl measured in this research, failure in unsaturated conditions is possible only where the gully head wall is significantly undercut. Head retreat thus requires the formation of either a tension crack or an undercut hollow. Finite-element stress analysis of eroding slopes reveals a build up of shear stress at the gully head base, and a second stress anomaly just upslope of the head wall. Although tension cracks on gully heads have often been attributed to slope unloading, this research provides strong evidence that the so called sapping hollow commonly found in the gully headwall base is also a function of stress release. Although further research is needed, it seems possible that pop out failures in river channels may be caused by the same process. The hydrological analysis shows that, once a tension crack has developed, throughflow velocity in the gully headwall will increase by an order of magnitude, promoting piping and enlargement of this weakened area. It is, therefore, possible to envisage a cycle of gully expansion in which erosion, channel incision or human action unloads the slope below a gully head, leading to stress patterns that account for the tension crack and a

  9. Glacier retreat accounts for more than 25 percent of summer runoff in the central Pamirs

    NASA Astrophysics Data System (ADS)

    Knoche, Malte; Lindner, Martin; Meier, Christiane; Pohl, Eric; Weise, Stephan; Merz, Ralf

    2014-05-01

    The Gunt River is a major headwater stream of the Amu-Darya River system, located in the Aral Sea basin. It drains a 14,000 km² basin in the Pamir Mountains ranging from 2000m to 6700m a.s.l with an average altitude of 4300m. Almost five percent or 610 km² of the Gunt basin is glaciated. The cold-arid catchment receives most precipitation in winter and spring and the runoff regime is dominated by snow and glacier melt. A remote sensing-based glacier monitoring was applied to measure glaciated area and its hypsometric distribution. Results show a decrease in area of 23.7 percent between 1977 and 2011. We ultimately deal with the question what impact glacier retreat has on the water balance in a typical headwater catchment of the Aral Sea basin. For this purpose we apply the GlabTop model to simulate glacier thickness distributions over the entire river basin and estimate changes in glacier volumes. Even though calibration sources are limited, uncertainty analyses show robustness in estimating volume changes. For the period from 1998 to 2011 we find the total ice volume being reduced by 11 percent or 4.6 km³. The ablation period was estimated using satellite-based snow-cover data and interpolated temperature data along with the glacier hypsometry. Temperature lapse-rates and their seasonal variance were derived from nine climate stations. Daily runoff time-series of 14 years (1998 - 2011) were analyzed. We find the ablation period to last 66 days on average. In that period, more than 25 percent of the total river discharge results from the retreat of glaciers. Hence, recent discharge is enriched by glacier retreat between mid of July and mid of September. The deglaciation will result in a significant reduction of river discharge in these months in future. We discuss uncertainties of the approach and potential impacts on the water resources in the Aral Sea basin, which is prone to water scarcity.

  10. Experimental Demonstration of Longitudinal Magnification

    ERIC Educational Resources Information Center

    Razpet, Nada; Susman, Katarina; Cepic, Mojca

    2009-01-01

    We describe an experiment which enables the observation of longitudinal magnification for the real image of a three-dimensional (3D) object formed by a converging lens. The experiment also shows the absence of longitudinal inversion. Possible reasons for misconceptions with respect to real images and longitudinal inversions are discussed and a…

  11. The Timing of Arctic Sea Ice Advance and Retreat as an Indicator of Ice-Dependent Marine Mammal Habitat

    NASA Astrophysics Data System (ADS)

    Stern, H. L.; Laidre, K. L.

    2013-12-01

    The Arctic is widely recognized as the front line of climate change. Arctic air temperature is rising at twice the global average rate, and the sea-ice cover is shrinking and thinning, with total disappearance of summer sea ice projected to occur in a matter of decades. Arctic marine mammals such as polar bears, seals, walruses, belugas, narwhals, and bowhead whales depend on the sea-ice cover as an integral part of their existence. While the downward trend in sea-ice extent in a given month is an often-used metric for quantifying physical changes in the ice cover, it is not the most relevant measure for characterizing changes in the sea-ice habitat of marine mammals. Species that depend on sea ice are behaviorally tied to the annual retreat of sea ice in the spring and advance in the fall. Changes in the timing of the spring retreat and the fall advance are more relevant to Arctic marine species than changes in the areal sea-ice coverage in a particular month of the year. Many ecologically important regions of the Arctic are essentially ice-covered in winter and ice-free in summer, and will probably remain so for a long time into the future. But the dates of sea-ice retreat in spring and advance in fall are key indicators of climate change for ice-dependent marine mammals. We use daily sea-ice concentration data derived from satellite passive microwave sensors to calculate the dates of sea-ice retreat in spring and advance in fall in 12 regions of the Arctic for each year from 1979 through 2013. The regions include the peripheral seas around the Arctic Ocean (Beaufort, Chukchi, East Siberian, Laptev, Kara, Barents), the Canadian Arctic Archipelago, and the marginal seas (Okhotsk, Bering, East Greenland, Baffin Bay, Hudson Bay). We find that in 11 of the 12 regions (all except the Bering Sea), sea ice is retreating earlier in spring and advancing later in fall. Rates of spring retreat range from -5 to -8 days/decade, and rates of fall advance range from +5 to +9

  12. Spiradenoma causing longitudinal splitting of the nail.

    PubMed

    Jha, A K; Sinha, R; Kumar, A; Bhadani, P; Kumar, S

    2016-10-01

    Longitudinal splitting of the nails can occur as a result of any growth arising in the nail matrix. We present a case of a 50-year-old woman who presented with an 18-month history of longitudinal splitting of the nail on her right little finger, along with pain in the proximal nail fold region, which was extremely tender to touch. Magnetic resonance imaging revealed an intensely enhancing lesion, while colour Doppler imaging revealed hypervascularity within the mass. A provisional diagnosis of glomus tumour was considered. Histopathology demonstrated presence of a well-circumscribed tumour comprising a dual population of cells, which stained negatively with periodic-acid-Schiff. The histopathological features were consistent with those of eccrine spiradenoma (ES). In this case, glomus tumour was considered as the first differential diagnosis, but histopathology confirmed it as an ES. PMID:27663150

  13. Accelerating retreat and high-elevation thinning of glaciers in central Spitsbergen

    NASA Astrophysics Data System (ADS)

    Małecki, Jakub

    2016-06-01

    Svalbard is a heavily glacier-covered archipelago in the Arctic. Dickson Land (DL), in the central part of the largest island, Spitsbergen, is relatively arid and, as a result, glaciers there are relatively small and restricted mostly to valleys and cirques. This study presents a comprehensive analysis of glacier changes in DL based on inventories compiled from topographic maps and digital elevation models for the Little Ice Age (LIA) maximum, the 1960s, 1990, and 2009/2011. Total glacier area has decreased by ˜ 38 % since the LIA maximum, and front retreat increased over the study period. Recently, most of the local glaciers have been consistently thinning in all elevation bands, in contrast to larger Svalbard ice masses which remain closer to balance. The mean 1990-2009/2011 geodetic mass balance of glaciers in DL is among the most negative from the Svalbard regional means known from the literature.

  14. Moral architecture: the influence of the York Retreat on asylum design.

    PubMed

    Edginton, B

    1997-06-01

    Institutional and architectural history places the asylum alongside the prison and other institutional types whose architectural characteristics emphasized confinement and control. This history obfuscates important differences in how ideas about treatment were represented in the particular design of these institutions; in other words, how the structure of a place became part of its discourse. What becomes obvious in nineteenth-century, asylum architecture is the influence of a small Yorkshire private asylum built by a Quaker, William Tuke, in 1796. The York Retreat, in form, solidified the ideas of 'moral treatment' in design and in turn assumed an exalted character in the design of late nineteenth-century asylums. Every researcher working in the field of the history of insanity acknowledges the importance of this event and its impact on the discourse of insanity for the century to follow. Few however talk about how its unique design was incorporated as part of this discourse.

  15. Attempts to retreat from a dead-ended long capillary by backward swimming in Paramecium

    PubMed Central

    Kunita, Itsuki; Kuroda, Shigeru; Ohki, Kaito; Nakagaki, Toshiyuki

    2014-01-01

    We have observed how the ciliate Paramecium attempts to retreat from the dead-end of a long capillary that is too narrow for turning. After many trial-and-error episodes of short-term backward swimming (SBS), which is the conventional avoidance behavior exhibited in free swimming when an obstacle is faced, long-term backward swimming (LBS) that lasted five to ten times longer was developed. LBS may have a beneficial effect for complete withdrawal from the capillary space, although in our experiment it was impossible for the organism to do so due to the capillary length. In order to identify a physically possible mechanism for LBS, we propose model equations for the membrane potential of Hodgkin–Huxley type, which describe the control of ciliary movement. The physiological implications and physical mechanism of the development of LBS are discussed. PMID:24966852

  16. Modeling the rate and style of Arctic coastal retreat along the Beaufort Sea, Alaska

    NASA Astrophysics Data System (ADS)

    Barnhart, K. R.; Anderson, R. S.; Overeem, I.; Wobus, C. W.; Clow, G. D.; Urban, F. E.; Lewinter, A. L.; Stanton, T. P.

    2011-12-01

    In Arctic landscapes, modern surface warming has significantly altered geomorphic process rates. Along the Beaufort Sea coastline bounding Alaska's North Slope, the mean annual coastal erosion rate has doubled from ~7 m/yr for 1955-1979 to ~14 m/yr for 2002-2007. Locally the erosion rate reaches 30 m/yr. A robust understanding of the processes that govern the rate of erosion is required in order to predict the response of the coast and its adjacent landscape to a rapidly changing climate, with implications for sediment and carbon fluxes, oilfield infrastructure, and animal habitat. On the Beaufort Sea coast, bluffs in regions of ice-rich silt-dominated permafrost are abundant. This type of coast is vulnerable to rapid erosion due to its high ice content and the small grain size of bluff sediment. The bluff material at our study site near Drew Point is 64% ice, making the bluff susceptible to thermal erosion. Liberated sediment is removed from the system in suspension and does not form sheltering beaches or barrier islands which would provide a negative feedback to erosion. During the sea ice-free season, relatively warm waters abut the bluff and ocean water melts a notch into the 4-m tall bluffs. The bluffs ultimately fail by the toppling of polygonal blocks bounded by mechanically weak ice-wedges that are spaced roughly 10-20 m apart. The blocks then temporarily armor the coast against further attack. We document the style and the drivers of coastal erosion in this region through simultaneous measurements of the oceanic and atmospheric conditions, and time-lapse imagery. We extract proxies for erosion rate from time-lapse imagery of both a degrading block and a retreating bluff from the summer of 2010, and compare the proxy record with environmental conditions and melt rate models. These observations verify that the dominant process by which erosion occurs is thermal insertion of a notch, toppling of blocks, and subsequent melting of the ice in the block. The

  17. Predicting Land-Ice Retreat and Sea-Level Rise with the Community Earth System Model

    SciTech Connect

    Lipscomb, William

    2012-06-19

    Coastal stakeholders need defensible predictions of 21st century sea-level rise (SLR). IPCC assessments suggest 21st century SLR of {approx}0.5 m under aggressive emission scenarios. Semi-empirical models project SLR of {approx}1 m or more by 2100. Although some sea-level contributions are fairly well constrained by models, others are highly uncertain. Recent studies suggest a potential large contribution ({approx}0.5 m/century) from the marine-based West Antarctic Ice Sheet, linked to changes in Southern Ocean wind stress. To assess the likelihood of fast retreat of marine ice sheets, we need coupled ice-sheet/ocean models that do not yet exist (but are well under way). CESM is uniquely positioned to provide integrated, physics based sea-level predictions.

  18. Late proterozoic and paleozoic tides, retreat of the moon, and rotation of the earth

    USGS Publications Warehouse

    Sonett, C.P.; Kvale, E.P.; Zakharian, A.; Chan, M.A.; Demko, T.M.

    1996-01-01

    The tidal rhythmites in the Proterozoic Big Cottonwood Formation (Utah, United States), the Neoproterozoic Elatina Formation of the Flinders Range (southern Australia), and the Lower Pennsylvanian Pottsville Formation (Alabama, United States) and Mansfield Formation (Indiana, United States) indicate that the rate of retreat of the lunar orbit is d??/dt k2 sin(2??) (where ?? is the Earth-moon radius vector, k2 is the tidal Love number, and ?? is the tidal lag angle) and that this rate has been approximately constant since the late Precambrian. When the contribution to tidal friction from the sun is taken into account, these data imply that the length of the terrestrial day 900 million years ago was -18 hours.

  19. [Endodontic re-treatment or apical surgery, is an evidence-based choice possible?].

    PubMed

    de Lange, J

    2016-02-01

    Treatment of a recurrence after an initial endodontic treatment can consist of endodontic re-treatment or apical surgery. The literature reports comparable success rates for these two options. However, randomised controlled trials that are truly comparable to each other are unavailable as a result of which comparison and an informed choice are not really possible. In addition to the treatment outcome, consideration also has to be given to cost-effectiveness and other patient-related factors, such as pain, swelling and medication. Regarding these considerations, too, little reliable information can be found in the literature. Moreover, factors relating to insurance play an important role in the Netherlands, where only apical surgery is covered by the basic healthcare insurance. In conclusion, all of these factors should be carefully considered before proceeding to an individual treatment strategy. PMID:26878715

  20. Muon cooling: longitudinal compression.

    PubMed

    Bao, Yu; Antognini, Aldo; Bertl, Wilhelm; Hildebrandt, Malte; Khaw, Kim Siang; Kirch, Klaus; Papa, Angela; Petitjean, Claude; Piegsa, Florian M; Ritt, Stefan; Sedlak, Kamil; Stoykov, Alexey; Taqqu, David

    2014-06-01

    A 10  MeV/c positive muon beam was stopped in helium gas of a few mbar in a magnetic field of 5 T. The muon "swarm" has been efficiently compressed from a length of 16 cm down to a few mm along the magnetic field axis (longitudinal compression) using electrostatic fields. The simulation reproduces the low energy interactions of slow muons in helium gas. Phase space compression occurs on the order of microseconds, compatible with the muon lifetime of 2  μs. This paves the way for the preparation of a high-quality low-energy muon beam, with an increase in phase space density relative to a standard surface muon beam of 10^{7}. The achievable phase space compression by using only the longitudinal stage presented here is of the order of 10^{4}.

  1. Muon Cooling: Longitudinal Compression

    NASA Astrophysics Data System (ADS)

    Bao, Yu; Antognini, Aldo; Bertl, Wilhelm; Hildebrandt, Malte; Khaw, Kim Siang; Kirch, Klaus; Papa, Angela; Petitjean, Claude; Piegsa, Florian M.; Ritt, Stefan; Sedlak, Kamil; Stoykov, Alexey; Taqqu, David

    2014-06-01

    A 10 MeV/c positive muon beam was stopped in helium gas of a few mbar in a magnetic field of 5 T. The muon "swarm" has been efficiently compressed from a length of 16 cm down to a few mm along the magnetic field axis (longitudinal compression) using electrostatic fields. The simulation reproduces the low energy interactions of slow muons in helium gas. Phase space compression occurs on the order of microseconds, compatible with the muon lifetime of 2 μs. This paves the way for the preparation of a high-quality low-energy muon beam, with an increase in phase space density relative to a standard surface muon beam of 107. The achievable phase space compression by using only the longitudinal stage presented here is of the order of 104.

  2. Cohort trends in premarital first births: what role for the retreat from marriage?

    PubMed

    England, Paula; Wu, Lawrence L; Shafer, Emily Fitzgibbons

    2013-12-01

    We examine cohort trends in premarital first births for U.S. women born between 1920 and 1964. The rise in premarital first births is often argued to be a consequence of the retreat from marriage, with later ages at first marriage resulting in more years of exposure to the risk of a premarital first birth. However, cohort trends in premarital first births may also reflect trends in premarital sexual activity, premarital conceptions, and how premarital conceptions are resolved. We decompose observed cohort trends in premarital first births into components reflecting cohort trends in (1) the age-specific risk of a premarital conception taken to term; (2) the age-specific risk of first marriages not preceded by such a conception, which will influence women's years of exposure to the risk of a premarital conception; and (3) whether a premarital conception is resolved by entering a first marriage before the resulting first birth (a "shotgun marriage"). For women born between 1920-1924 and 1945-1949, increases in premarital first births were primarily attributable to increases in premarital conceptions. For women born between 1945-1949 and 1960-1964, increases in premarital first births were primarily attributable to declines in responding to premarital conceptions by marrying before the birth. Trends in premarital first births were affected only modestly by the retreat from marriages not preceded by conceptions-a finding that holds for both whites and blacks. These results cast doubt on hypotheses concerning "marriageable" men and instead suggest that increases in premarital first births resulted initially from increases in premarital sex and then later from decreases in responding to a conception by marrying before a first birth.

  3. Origin of oroclines in Paleozoic Australia: the role of inherited plate boundary irregularities and trench retreat

    NASA Astrophysics Data System (ADS)

    Rosenbaum, G.; Shaanan, U.; Hoy, D.; Abdullah, R.

    2015-12-01

    Paleozoic Australia is made of a series of orogenic belts that include the Delamerian, Lachlan and New England orogens, as well as the poorly defined Thomson Orogen. The origin of these belts has been attributed to subduction and accretionary processes along the ~N-S-striking (present coordinates) plate boundary of Gondwana. However, recent studies show that orogenic segments are strongly contorted, thus raising questions about the geodynamic origin of eastern Australia and Paleozoic plate tectonics in general. Results from the New England Orogen revealed that oroclinal bending has occurred simultaneously with basin formation and trench retreat. Geochronological provenance studies of detrital zircon show that these basins were situated in a back-arc position, indicating that back-arc extension may have played a crucial role in oroclinal bending. In addition, geochronological data of detrital zircon show that terranes that were once considered to be exotic were actually derived from local sources. The collective geological evidence suggests that deformation and oroclinal bending were driven by subduction-related processes possibly acting on inherited irregularities in the orientation of the plate boundary. The irregular geometries were further accentuated by trench migration (retreat and advance) that led to subduction segmentation, oroclinal bending, and alternating episodes of contraction and (back-arc) extension. In search of inherited plate boundary irregularities in Paleozoic Australia, we have studied the ~E-W boundary between the Lachlan and Thomson orogens. This lithospheric-scale boundary may reflect the original geometry of the plate boundary, which might have accommodated hundreds of km of dextral offset. This boundary may be part a much larger orogenic curvature, hitherto not recognised, and the development of which may have played a fundamental role in the formation of the smaller-scale oroclines in the Lachlan and New England orogens.

  4. Geomorphic response of rivers to glacial retreat and increasing peak flows downstream from Mount Rainier, Washington

    NASA Astrophysics Data System (ADS)

    Czuba, J. A.; Barnas, C. R.; Magirl, C. S.; Voss, F. D.

    2010-12-01

    On Mount Rainier, Washington, the National Park Service has documented widespread aggradation of as much as 10 m since the early 20th century, of rivers draining the glaciated stratovolcano. This rapid sedimentation appears to be related to glacial retreat and also may be a function of the increased magnitude and timing of peak flows that mobilize and transport sediment. We are conducting an assessment of the Puget Lowland rivers that drain Mount Rainier, 25-100 km downstream from the park boundary, to document the geomorphic response of the downstream reaches given the widespread aggradation upstream. These downstream reaches provide critical aquatic habitat for spawning and rearing of several species of salmonids, including endangered Chinook salmon and steelhead. Fluvial sedimentation can have both deleterious and beneficial effects on aquatic habitat depending on sediment particle size, river slope and width, and river management. To date, our work shows sedimentation of as much as 2 m between 1984 and 2009 in these lowland rivers. Aggradation rates that were calculated by comparing channel change at 156 cross sections, ranged between 4.8 and 9.1 cm/yr in reaches where rivers exit the mountain front and enter the lowland. Analysis of streamflow-gaging station data from throughout the watersheds draining Mount Rainier show rapid incision and aggradation, suggesting pulses of coarse-grained bedload may be moving down the mountainous rivers as kinetic waves. Preliminary results, however, seem to indicate that the rivers in the Puget Lowland have not yet experienced significant widespread sedimentation directly related to glacial retreat. Estimating the time of arrival of mobilized alluvium is a critical need for resource managers given the potential effects of sedimentation on river flood-conveyance capacity, fish habitat, and estuarine wetlands.

  5. Cohort Trends in Premarital First Births: What Role for the Retreat From Marriage?

    PubMed Central

    Wu, Lawrence L.; Shafer, Emily Fitzgibbons

    2015-01-01

    We examine cohort trends in premarital first births for U.S. women born between 1920 and 1964. The rise in premarital first births is often argued to be a consequence of the retreat from marriage, with later ages at first marriage resulting in more years of exposure to the risk of a premarital first birth. However, cohort trends in premarital first births may also reflect trends in premarital sexual activity, premarital conceptions, and how premarital conceptions are resolved. We decompose observed cohort trends in premarital first births into components reflecting cohort trends in (1) the age-specific risk of a premarital conception taken to term; (2) the age-specific risk of first marriages not preceded by such a conception, which will influence women’s years of exposure to the risk of a premarital conception; and (3) whether a premarital conception is resolved by entering a first marriage before the resulting first birth (a “shotgun marriage”). For women born between 1920–1924 and 1945–1949, increases in premarital first births were primarily attributable to increases in premarital conceptions. For women born between 1945–1949 and 1960–1964, increases in premarital first births were primarily attributable to declines in responding to premarital conceptions by marrying before the birth. Trends in premarital first births were affected only modestly by the retreat from marriages not preceded by conceptions—a finding that holds for both whites and blacks. These results cast doubt on hypotheses concerning “marriageable” men and instead suggest that increases in premarital first births resulted initially from increases in premarital sex and then later from decreases in responding to a conception by marrying before a first birth. PMID:24072609

  6. Effects of Emergent Vegetation on Sediment Dynamics within a Retreating Coastal Marshland

    NASA Astrophysics Data System (ADS)

    Stellern, C.; Grossman, E.; Fuller, R.; Wallin, D.; Linneman, S. R.

    2015-12-01

    Coastal emergent vegetation in estuaries physically interrupts flow within the water column, reduces wave energy and increases sediment deposition. Previous workers conclude that wave attenuation rates decrease exponentially with distance from the marsh edge and are dependent on site and species-specific plant characteristics (Yang et al., 2011). Sediment deposition may exhibit similar patterns; however, sediment, geomorphic and habitat models seldom integrate site-specific biophysical plant parameters into change analyses. We paired vegetation and sediment dynamic studies to: (1) characterize vegetation structure, (2) estimate sediment available for deposition, (3) estimate rate, distribution and composition of sediment deposits, (4) determine sediment accumulation on vegetation, (5) compare sediment deposition within dense tidal wetland relative to non-vegetated tidal flat. These studies integrate a variety of monitoring methods, including the use of sediment traps, turbidity sensors, side-on photographs of vegetation and remote sensing image analysis. We compared sedimentation data with vegetation characteristics and spatial distribution data to examine the relative role of vegetation morphologic traits (species, stem density, biomass, distribution, tidal channels, etc.) on sediment dynamics. Our study is focused on Port Susan Bay of Washington State; a protected delta that has experienced up to 1 kilometer of marsh retreat (loss) over the past fifty years. Preliminary results show that the highest winter deposition occurred in the high marsh/mid-marsh boundary, up to 300m inland of the marsh edge, where bulrush species are most dense. These results will inform restoration efforts aimed at reestablishing sediment supply to the retreating marshland. This research is necessary to understand the vulnerability and adaptability of coastal marshlands to climate change related stressors such as, increased water levels (sea-level rise) and wave energy.

  7. A Hybrid Key Predistribution Scheme for Sensor Networks Employing Spatial Retreats to Cope with Jamming Attacks

    NASA Astrophysics Data System (ADS)

    Panyim, Korporn; Krishnamurthy, Prashant

    In order to provide security services in wireless sensor networks, a well-known task is to provide cryptographic keys to sensor nodes prior to deployment. It is difficult to assign secret keys for all pairs of sensor node when the number of nodes is large due to the large numbers of keys required and limited memory resources of sensor nodes. One possible solution is to randomly assign a few keys to sensor nodes and have nodes be able to connect to each other with some probability. This scheme has limitations in terms of the tradeoffs between connectivity and memory requirements. Recently, sensor deployment knowledge has been used to improve the level of connectivity while using lesser amounts of memory space. Jamming attacks are an easy and efficient means for disruption of the connectivity of sensors and thus the operation of a sensor network. One solution for mobile sensor nodes to overcome the impact of jamming is to perform spatial retreat by moving nodes away from jammed regions. However, deployment based key predistribution schemes may cause a large number of nodes to be cryptographically isolated after they move out of the jammed area. Moved nodes may not be able to reconnect to the network because they do not have any shared secret with new neighbors at new locations. In this paper, we propose a hybrid key predistribution scheme that supports spatial retreat strategies to cope with jamming attacks. Our scheme combines the properties of random and deployment knowledge based key predistribution schemes. In the presence of jamming attacks, our scheme provides high key connectivity (similar to deployment knowledge based schemes) while reducing the number of isolated nodes. We evaluate the performance of our scheme through simulations and analysis.

  8. The Ellsworth Subglacial Highlands and the inception and retreat of the West Antarctic Ice Sheet

    NASA Astrophysics Data System (ADS)

    Ross, N.; Siegert, M. J.; Bingham, R. G.; Corr, H. F. J.; Ferraccioli, F.; Jordan, T. A.; Le Brocq, A.; Rippin, D.

    2012-04-01

    Laying on a bed in places >2km below sea level, the West Antarctic Ice Sheet (WAIS) is thought to be prone to major rapid decay due to melting from the ocean, which induces grounding line retreat. A feedback may occur, in which migration of the grounding line to deeper regions leads to further ice loss. Highland regions of the subglacial bed will act both as seeding centres for ice sheet growth and points of stability ('pinning points') during ice sheet recession. While several highland regions exist beneath the WAIS, none have been confirmed as ice sheet seeding centres/pinning points. Studies of subglacial East Antarctica have demonstrated the utility of radio-echo sounding (RES) in the identification of glacial geomorphology from which past ice sheet conditions can be appreciated. Here, we characterise the detailed glacial morphology of the Ellsworth Subglacial Highlands (ESH), from ground-based and airborne RES surveys. We document well-preserved classic features associated with restricted, dynamic, marine-proximal alpine glaciation, with hanging tributary valleys feeding significant over-deepened troughs cut by valley (tidewater) glaciers. Fjord-mouth threshold bars down-ice of overdeepenings define the termini of palaeo outlet-glaciers. We show how MODIS satellite imagery of the ice surface reflects the gross subglacial morphology. The imagery reveals numerous glaciated valleys cutting through the ESH, terminating at the edge of the deep Bentley Subglacial Trench. The landscape obviously predates the present ice sheet, and is likely to have been formed by a small dynamic ice cap at times when the marine sections of the WAIS were absent. As well as acting as a key WAIS seeding point, the ESH would be critical for 'pinning' the ice sheet during any large-scale retreat event.

  9. Glacier retreat and associated sediment dynamics in proglacial areas: a case study from the Silvretta Alps, Austria

    NASA Astrophysics Data System (ADS)

    Felbauer, Lucia; Pöppl, Ronald

    2016-04-01

    Global warming results in an ongoing retreat of glaciers in the Alps, leaving behind large amounts of easily erodible sediments. In addition, the debuttressing of rock-walls and the decay of permafrost in the high mountain regions facilitates mass movements of potential disastrous consequences, such as rock falls, landslides and debris flows. Therefore, it is highly important to quantify the amount of sediments that are supplied from the different compartments and to investigate how glacial retreat influences sediment dynamics in proglacial areas. In the presented work glacier retreat and associated sediment dynamics were investigated in the Kromer valley (Silvretta Alps, Austria) by analyzing remote sensing data. Glacial retreat from the period of 1950 to 2012 was documented by interpreting aerial photographs. By digitizing the different stages of the glaciers for six time frames, changes in glacier area and length were mapped and quantified. In order to identify, characterize and quantify sediment dynamics in the proglacial areas a high resolution DEM of difference (DoD) between 2007 and 2012 was created and analyzed, further differentiating between different zones (e.g. valley bottom, hillslope) and types of geomorphic processes (e.g. fluvial, gravitational). First results will be presented at the EGU General Assembly 2016.

  10. Grounding line retreat of Pope, Smith, and Kohler Glaciers, West Antarctica, measured with Sentinel-1a radar interferometry data

    NASA Astrophysics Data System (ADS)

    Scheuchl, B.; Mouginot, J.; Rignot, E.; Morlighem, M.; Khazendar, A.

    2016-08-01

    We employ Sentinel-1a C band satellite radar interferometry data in Terrain Observation with Progressive Scans mode to map the grounding line and ice velocity of Pope, Smith, and Kohler glaciers, in West Antarctica, for the years 2014-2016 and compare the results with those obtained using Earth Remote Sensing Satellites (ERS-1/2) in 1992, 1996, and 2011. We observe an ongoing, rapid grounding line retreat of Smith at 2 km/yr (40 km since 1996), an 11 km retreat of Pope (0.5 km/yr), and a 2 km readvance of Kohler since 2011. The variability in glacier retreat is consistent with the distribution of basal slopes, i.e., fast along retrograde beds and slow along prograde beds. We find that several pinning points holding Dotson and Crosson ice shelves disappeared since 1996 due to ice shelf thinning, which signal the ongoing weakening of these ice shelves. Overall, the results indicate that ice shelf and glacier retreat in this sector remain unabated.

  11. Longitudinal emittance measurements in the Fermilab Recycler Ring

    SciTech Connect

    C. M. Bhat; John P. Marriner

    2003-06-10

    The Recycler Ring (RR) is a new 8Gev antiproton storage ring at Fermilab. Presently, this machine is being commissioned using protons from the Booster. It uses barrier buckets for stacking, un-stacking and storing the beam. At any given time, the RR is capable of storing proton or antiproton beams in multiple segments azimuthally. These segments of the beam may have widely differing longitudinal emittance and beam intensities and bunch lengths. It is highly essential to be able to measure the longitudinal emittance and keep track of the longitudinal dynamics at various stages of the operation of the RR. In this paper, the authors discuss a few methods of longitudinal emittance measurements in barrier buckets and discuss their merits and demerits

  12. Ice sheet retreat dynamics inferred from glacial morphology of the central Pine Island Bay Trough, West Antarctica

    NASA Astrophysics Data System (ADS)

    Jakobsson, Martin; Anderson, John B.; Nitsche, Frank O.; Gyllencreutz, Richard; Kirshner, Alexandra E.; Kirchner, Nina; O'Regan, Matthew; Mohammad, Rezwan; Eriksson, Björn

    2012-03-01

    Pine Island Glacier drains portions of the West Antarctic Ice Sheet into the Amundsen Sea. During the Last Glacial Maximum the glacier extended nearly 500 km from its present location onto the outer continental shelf. Unusually restricted sea-ice cover during the austral summer of 2010 allowed for a systematic multibeam swath-bathymetric and chirp sonar survey of the mid-shelf section of Pine Island Trough. The mapped glacial landforms reveal new information about the paleo-Pine Island Ice Stream's dynamic retreat from the mid-shelf area and confirm previous suggestion of a retreat in distinct steps. The periods of grounding line stability during the overall retreat phase are marked by sediment accumulations, i.e. grounding zone wedges. These wedges are here mapped in sufficient detail to characterize spatial dimensions and estimate the volume of deposited sediment. Considering a range of sediment flux rates from the paleo-Pine Island Ice Stream we estimate that the largest and most clearly defined grounding zone wedge, located at about 73°S in the surveyed area, took between 600 and 2000 years to form. The ice stream retreated landward of this wedge before 12.3 cal ka BP. The swath-bathymetric imagery of landforms in Pine Island Trough includes glacial features that suggest that retreat between periods of grounding line stability may be associated with episodes of ice shelf break-up. The depths of grounding line wedges decrease in a landward direction, from 740 to 670 m, and record elevation of the grounding line as it stepped landward. In all, the grounding line elevation varied by only ˜80 m over a distance of just over 100 km, implying a low ice sheet profile during retreat. Finally, we revisited seismic reflection profile NB9902, acquired along Pine Island Trough in 1999, in combination with the newly acquired swath-bathymetric imagery from 2010. Together these data show that the ice stream paused during its retreat to form grounding zone wedges at an area

  13. Evaluating the effectiveness of enhancing resilience in human service professionals using a retreat-based Mindfulness with Metta Training Program: a randomised control trial.

    PubMed

    Pidgeon, Aileen M; Ford, Lucas; Klaassen, Frances

    2014-01-01

    This paper explores the feasibility of a brief Mindfulness with Metta Training Program (MMTP), targeting the enhancement of mindfulness and self-compassion in a retreat format, as a means of increasing resilience in human services professionals. In this randomised control trial, 44 human services professionals were randomly allocated either to a MMTP retreat group or to a control group. Following the MMTP intervention, no significant differences between the retreat and control groups were found on resilience, mindfulness and self-compassion variables. However, significant improvements were observed over time for the retreat group for mindfulness and self-compassion at one and four months and for resilience at four-months post MMTP intervention. The results of this pilot study show that MMTP in a retreat format is a promising method of increasing resilience, mindfulness and self-compassion in human services professionals.

  14. Contribution of longitudinal electric field of a gaussian beam to second harmonic generation

    NASA Astrophysics Data System (ADS)

    Mishra, S. R.; Rustagi, K. C.

    1990-01-01

    A laser beam with a nonuniform transverse intensity profile necessarily has a longitudinal component of the electric field. We show that a detectable second harmonic can be generated due to coupling of this longitudinal component with the transverse field of a gaussian beam in a configuration in which second harmonic generation is forbidden for plane wave interaction.

  15. Evidence for the asynchronous retreat of large outlet glaciers in southeast Greenland at the end of the last glaciation

    NASA Astrophysics Data System (ADS)

    Dyke, Laurence M.; Hughes, Anna L. C.; Murray, Tavi; Hiemstra, John F.; Andresen, Camilla S.; Rodés, Ángel

    2014-09-01

    Recent rapid changes in the marine-terminating sectors of the Greenland Ice Sheet (GrIS) have prompted concerns about the future stability of the ice sheet. Long-term records of ice sheet behaviour provide valuable context to assess the magnitude of current change and may help resolve the mechanisms driving deglaciation. We report 23 new 10Be exposure ages which constrain the deglacial history of two large fjord systems in southeast (SE) Greenland. We compare our chronologies with existing data from the centre of the sector to examine the timing and style of deglaciation at a regional-scale. Glacial erratic 10Be exposure ages demonstrate that Kangerdlugssuaq Fjord deglaciated at ˜11.8 ka at the end of the Younger Dryas (YD - 12.8-11.6 ka). Retreat at Kangerdlugssuaq Fjord coincided with known incursion of the warm Irminger Current (IC) onto the continental shelf; this is inferred to have initiated retreat. Comparison with recently published results from Sermilik Fjord and new 10Be ages from Bernstorffs Fjord indicates deglaciation occurred ˜1 ka later in the south of the SE region. Sermilik Fjord (˜10.9 ka) and Bernstorffs Fjord (˜10.4 ka) deglaciated later; retreat likely occurred in response to dramatic climatic amelioration at the termination of the YD stadial. We suggest that the disparate timing of deglaciation across the SE region may be primarily explained by the varying influence of the warm IC; glaciers in southern SE Greenland were isolated from warm Atlantic waters during the YD by complex shelf bathymetry. In all fjord settings ice retreat was rapid and persistent, consistent with the absence of geomorphological evidence for stillstand or readvance events. Ice retreat was accompanied by rapid thinning and likely continued to well within present-day ice sheet margins. Glacial erratic 10Be age determinations and geomorphological observations show no evidence for Holocene readvance events prior to the Little Ice Age (LIA).

  16. Retreatment with bevacizumab in patients with gynecologic malignancy is associated with clinical response and does not increase morbidity

    PubMed Central

    Laskey, Robin A; Richard, Scott D; Smith, Ashlee L; Lin, Jeff F; Beck, Tiffany L; Lesnock, Jamie L; Kelley, Joseph L; Olawaiye, Alexander B; Sukumvanich, Paniti; Krivak, Thomas C

    2014-01-01

    Purpose Bevacizumab (Bev) is associated with improved progression-free survival in advanced epithelial ovarian cancer. The use of Bev in patients with gynecologic malignancy is increasing; however, little is known about cumulative toxicity and response in patients retreated with Bev. Our goal was to determine cumulative side effects and response in patients retreated with Bev. Patients and methods Women with recurrent gynecologic malignancy treated with Bev between January 2007 and March 2012 at a single institution were identified, including a subset who received Bev in a subsequent regimen. The primary outcome was Bev-associated toxicity, and the secondary outcome was response. Results Of 83 patients that received Bev for recurrent disease, 23 were retreated with Bev and four received Bev maintenance. Three patients (13%) developed grade 3 or 4 hypertension; all had a history of chronic hypertension. One (4.3%) patient developed grade 3 proteinuria, and one (4.3%) developed an enterovaginal fistula. Four patients discontinued Bev secondary to toxicity. Toxicity was not related to the cumulative number of cycles. Twenty-six percent of patients responded to Bev retreatment. On univariate analysis, there was a significant (P=0.003) overall survival advantage when the Bev-free interval was >9 months (95% confidence interval [CI] 4.9–43.7) compared to ≤9 months (95% CI 2.1–11.5), 24.3 months, and 6.8 months. Conclusion Retreatment of patients with recurrent gynecologic malignancy with Bev did not increase morbidity and was associated with treatment response. Physicians treating women with recurrent disease may consider a Bev-containing regimen even if prior regimen(s) included Bev. Future studies should prospectively evaluate the efficacy of this treatment strategy. PMID:24711703

  17. Peeking Under the Ice… Literally: Records of Arctic Climate Change from Radiocarbon Dating Moss Emerging from Beneath Retreating Glaciers

    NASA Astrophysics Data System (ADS)

    Briner, J. P.; Schweinsberg, A.; Miller, G. H.; Lifton, N. A.; Beel, C. R.; Bennike, O.

    2014-12-01

    Dramatic changes are taking place throughout the Arctic. Many glaciers have already melted away completely, and most others are well on their way as rising snowline elevations promise continued glacier retreat. Emerging from beneath retreating glacier margins is a landscape rich in information about past climate and glacier changes. Within newly exposed bedrock is an inventory of cosmogenic nuclides that archive past ice cover timing and duration. Lake basins re-appearing due to retreating ice preserve sediment archives that tell of cooling climate and advancing ice. And ancient surfaces vegetated with tundra communities that have long been entombed beneath frozen-bedded ice caps are now being revealed for the first time in millennia. This presentation will focus on the climate and glacier record derived from radiocarbon dating of in situ moss recently exhumed from retreating local ice cap margins on western Greenland. Dozens of radiocarbon ages from moss group into several distinct modes, which are interpreted as discrete times of persistent summer cooling and resultant glacier expansion. The data reveal a pattern of glacier expansion beginning ~5000 years ago, followed by periods of glacier growth around 3500 and 1500 years ago. Because these times of glacier expansion are recorded at many sites in western Greenland and elsewhere in the Arctic, they are interpreted as times of step-wise summer cooling events during the Holocene. These non-linear climate changes may be a result of feedbacks that amplify linear insolation forcing of Holocene climate. In addition to these insights into the Arctic climate system, the antiquity of many radiocarbon ages of ice-killed moss indicate that many arctic surfaces are being re-exposed for the first time in millennia due to retreating ice, emphasizing the unprecedented nature of current summer warming.

  18. The landslide response of alpine basins to post-Little Ice Age glacial thinning and retreat in southwestern British Columbia

    NASA Astrophysics Data System (ADS)

    Holm, Kris; Bovis, Michael; Jakob, Matthias

    2004-02-01

    The role of post-Little Ice Age (LIA) Neoglacial retreat on landslide activity is investigated in 19 alpine basins along the upper Lillooet River Valley, British Columbia. We examine how Neoglacial scouring and glacial recession have modified hillslope form and slope stability, and construct a decision-making flowchart to identify landslide hazards associated with glacial retreat. This work is based on field mapping, GIS analysis, statistical associations between landslides and terrain attributes, and a comparison between Neoglaciated and non-Neoglaciated terrain within each basin. The bedrock landslide response to glacial retreat varies appreciably according to lithology and the extent of glacial scour below the LIA trimline. Valleys carved in weak Quaternary volcanics show significant erosional oversteepening and contain deep-seated slope movement features, active rock fall, rock slides, and rock avalanches near glacial trimlines. Basins in stronger granitic rock rarely show increased bedrock instability resulting from post-LIA retreat, except for shallow-seated rock slides along some trimlines and failures on previously unstable slopes. In surficial materials, landslides associated with post-LIA retreat originate in till or colluvium, as debris slides or debris avalanches, and are concentrated along lateral moraines or glacial trimlines. Significant spatial association was also observed between recent catastrophic failures, gravitational slope deformation, and slopes that were oversteepened then debuttressed by glacial erosion. Eight out of nine catastrophic rock slope failures occurred just above glacial trimlines and all occurred in areas with a previous history of deep-seated gravitational slope movement, implying that this type of deformation is a precursor to catastrophic detachment.

  19. ISSUES AND CHALLENGES IN MODELING CHILDREN'S LONGITUDINAL EXPOSURES: AN OZONE STUDY

    EPA Science Inventory

    Modeling children's exposures is a complicated, data-intensive process. Modeling longitudinal exposures, which are important for regulatory decision making, especially for most air toxics, adds another level of complexity and data requirements. Because it is difficult to model in...

  20. Historical analysis and visualization of the retreat of Findelengletscher, Switzerland, 1859-2010

    NASA Astrophysics Data System (ADS)

    Rastner, P.; Joerg, P. C.; Huss, M.; Zemp, M.

    2016-10-01

    Since the end of the Little Ice Age around 1850, glaciers in Europe have strongly retreated. Thanks to early topographic surveys in Switzerland, accurate maps are available, which enable us to trace glacier changes back in time. The earliest map for all of Switzerland that is usable for a detailed analysis is the Dufour map from around 1850 with subsequent topographic maps on a ~ 20 year interval. Despite the large public and scientific interest in glacier changes through time, this historic dataset has not yet been fully utilized for topographic change assessment or visualization of historic glacier extents. In this study, we use eleven historical topographic maps and more recent digital datasets for the region of Zermatt to analyze geometric changes (length, area and volume) of Findelengletscher as well as for creating animations of glacier evolution through time for use in public communication. All maps were georeferenced, the contour lines digitized, and digital elevation models (DEMs) created and co-registered. Additional digital data like the SRTM X-band DEM and high resolution laser scanning data were used to extend the analysis until 2010. Moreover, one independent DEM from aerial photogrammetry was used for comparison. During the period 1859-2010, Findelengletscher lost 3.5 km of its length (6.9 km in 2010), 4.42 ± 0.13 km2 of its area (15.05 ± 0.45 km2 in 2010) and 1.32 ± 0.52 km3 of its volume. The average rate of thickness loss is 0.45 ± 0.042 m yr- 1 for the 151 years period. Four periods with high thickness change from - 0.56 m ± 0.28 yr- 1 (1859-1881), - 0.40 ± 0.08 m yr- 1 (1937-1965), - 0.90 ± 0.31 m yr- 1 (1995-2000) and - 1.18 ± 0.02 m yr- 1 (2000-2005) have been identified. Small positive thickness changes were found for the periods 1890-1909 (+ 0.09 ± 0.46 m yr- 1) and 1988-1995 (+ 0.05 ± 0.24 m yr- 1). During its retreat with intermittent periods of advance, the glacier separated into three parts. The above changes are demonstrated

  1. Mapping seabed geomorphology in the Inner Hebrides, Scotland; Bathymetric records of ice streaming and retreat

    NASA Astrophysics Data System (ADS)

    Dove, Dayton; Finlayson, Andrew; Bradwell, Tom; Arosio, Riccardo; Howe, John

    2014-05-01

    Approximately 7,000 km² of new bathymetry have been stitched together with onshore airborne radar data, both gridded at 5m resolution, to map and describe the submarine glacial landscape of the Inner Hebrides sector of the former British-Irish Ice Sheet (BIIS). As part of the MAREMAP Project (http://www.maremap.ac.uk), and to build on previous work (Howe et al., 2012), we are using recently acquired swath bathymetry data, collected primarily by the UKHO Civil Hydrography Programme, to characterise the geomorphology, sea-bed sediments, and bedrock geology of the Inner Hebrides region. Mapping has revealed an extensive array of well-preserved glacigenic landforms on the seabed associated with key stages of ice flow and retreat of the BIIS following the Last Glacial Maximum. On multiple submarine rock platforms and within overdeepened troughs, diverse assemblages of glacially streamlined landforms are present, forming a geomorphic continuum between rock drumlins and mega-flutes. Superimposed streamlined bedforms indicate different phases of fast flow at the ice sheet bed, and the convergence of flow sets suggest that ice sheet flow was organised into faster flowing topographically controlled corridors. Across the region, the streamlined landforms occur within a geographically controlled zone, semi-independent of the underlying geology. This is consistent with the onset zone of the Hebrides Ice Stream, as previously postulated (Howe et al., 2012). Submarine moraine ridges are observed widely across the survey area: within sea lochs, atop rock platforms and superimposed on glacially streamlined bedforms, as well as pinned to topographic highs (i.e. islands). Some retreat patterns reveal clear glacial recession towards respective catchments, while others are more ambiguous and are the focus of ongoing work. The bathymetry data notably reveal more geomorphic evidence of glaciation than adjacent land records, thus providing the opportunity to reassess onshore mapping

  2. Modeling extreme beach retreat and erosion volumes. A tool for susceptibility analysis.

    NASA Astrophysics Data System (ADS)

    Trindade, J.; Ramos-Pereira, A.

    2012-04-01

    Beaches are among the most dynamic systems in the coastal zone. This is due to the great variability in the main triggering factors that contribute to morphological change. Dramatic coast line retreat can occur in a short period of time due to episodic extreme wave events endangering people and property and therefore defining the local susceptibility to erosion. This research aims to determinate beach recession and volume erosion due to sediment loss during extreme wave events in non artificialized beaches of the Portuguese west coast, for susceptibility analysis. The central west coast of Portugal is a wave dominated high energetic coastal environment. Storm frequency and magnitude are very important features on the definition of the annual local sediment budget and on the anthropogenic elements exposure to the direct action of waves through momentary or permanent coastline retreat. Winter offshore mean significant wave values reach 2.5m and waves with a 5 year recurrence period can be higher than 9m. Results of cross- shore beach profile modeling using storm-induced beach change model (SBEACH) are presented for 3 beach systems, namely Sta. Rita beach, Azul beach and Foz do Lizandro. The calibration tests and the validation process are described and presented. The model run results are based on high definition natural beach profile data of pre- and post-storm measured morphology, on local characteristics of beach sediments and on hydrodynamic variables related to onshore extreme wave data and local tide heights. Results point out the crucial importance of the local calibration process for the model application, with adjusted values of the transport rate coefficient, K, and the coefficient for slope dependent term, ɛ, differing from the "recommended" values by excess. In most cases validation values show that the locally calibrated SBEACH model explains 90% of the observed volume changes between pre- and post-storm profiles, computing sediment loss by slight

  3. The Effectiveness of ART Score in Selecting Patients for Transarterial Chemoembolization Retreatment

    PubMed Central

    Tseng, Chi-Lung; Lai, Wei-Jen; Huang, Chun-Jui; Huang, Yi-Hsiang; Su, Chien-Wei; Lee, I-Cheng; Tseng, Hsiou-Shan; Li, Chung-Pin; Lee, Rheun-Chuan; Lin, Han-Chieh; Chao, Yee

    2015-01-01

    Abstract The major issue in selecting patients for transarterial chemoembolization (TACE) lies in determining the optimal number of TACE sessions that may benefit patients before switching to other therapies. This is often a subjective decision not based on any standardized protocol. The ART (Assessment for Retreatment with Transarterial chemoembolization) score was recently developed to determine patients who may benefit from multiple sessions of TACE for treatment of hepatocellular carcinoma. The primary aim of the study was to validate the ART score in a Taiwanese cohort. The secondary aims were to evaluate overall survival and clinical determinants of improved survival in patients treated with multiple TACE sessions. The ART score, clinical characteristics, and outcomes of 82 patients with hepatocellular carcinoma who received multiple TACE sessions at Taipei Veterans General Hospital from September 2007 to July 2013 were analyzed. Among the 82 patients evaluated, 69.5% (n = 57) had an ART score of 0 to 1.5 and 34.1% (n = 25) had a score of ≥2.5. The median overall survival was 23.1 months and the overall mortality rate was 62.2% (n = 51). The ART score was not associated with survival (P = 0.58). Multivariate Cox regression analysis revealed that tumor size >7.2 cm (hazard ratio 4.44, P < 0.001), aspartate transaminase (AST) level above 95 IU/L (hazard ratio 2.18, P = 0.02), AST increase more than 25% (hazard ratio 2.13, P = 0.02), 2nd/1st (pre-TACE) alpha-fetoprotein ratio (hazard ratio 1.40, P = 0.001), and lack of radiological response to TACE (hazard ratio 2.21, P = 0.02) were independent clinical determinants of survival. The ART score was not found to be effective in selecting patients for TACE retreatment in our Taiwanese cohort. Large tumor size, high AST level, high 2nd/1st (pre-TACE) alpha-fetoprotein ratio, AST increase >25%, and lack of radiological response to TACE were independently associated with

  4. Nucleon Spin Structure: Longitudinal and Transverse

    SciTech Connect

    Jian-Ping Chen

    2011-02-01

    Inclusive Deep-Inelastic Scattering (DIS) experiments have provided us with the most extensive information on the unpolarized and longitudinal polarized parton (quark and gluon) distributions in the nucleon. It has becoming clear that transverse spin and transverse momentum dependent distributions (TMDs) study are crucial for a more complete understanding of the nucleon structure and the dynamics of the strong interaction. The transverse spin structure and the TMDs are the subject of increasingly intense theoretical and experimental study recently. With a high luminosity electron beam facility, JLab has played a major role in the worldwide effort to study both the longitudinal and transverse spin structure. Highlights of recent results will be presented. With 12-GeV energy upgrade, JLab will provide the most precise measurements in the valence quark region to close a chapter in longitudinal spin study. JLab will also perform a multi-dimensional mapping of the transverse spin structure and TMDs in the valence quark region through Semi-Inclusive DIS (SIDIS) experiments, providing a 3-d partonic picture of the nucleon in momentum space and extracting the u and d quark tensor charges of the nucleon. The precision mapping of TMDs will also allow a detailed study of the quark orbital motion and its dynamics.

  5. Modeling nonstationary longitudinal data.

    PubMed

    Núñez-Antón, V; Zimmerman, D L

    2000-09-01

    An important theme of longitudinal data analysis in the past two decades has been the development and use of explicit parametric models for the data's variance-covariance structure. A variety of these models have been proposed, of which most are second-order stationary. A few are flexible enough to accommodate nonstationarity, i.e., nonconstant variances and/or correlations that are not a function solely of elapsed time between measurements. We review five nonstationary models that we regard as most useful: (1) the unstructured covariance model, (2) unstructured antedependence models, (3) structured antedependence models, (4) autoregressive integrated moving average and similar models, and (5) random coefficients models. We evaluate the relative strengths and limitations of each model, emphasizing when it is inappropriate or unlikely to be useful. We present three examples to illustrate the fitting and comparison of the models and to demonstrate that nonstationary longitudinal data can be modeled effectively and, in some cases, quite parsimoniously. In these examples, the antedependence models generally prove to be superior and the random coefficients models prove to be inferior. We conclude that antedependence models should be given much greater consideration than they have historically received.

  6. Scanning electron microscopy with energy dispersive X-ray spectrophotometry analysis of reciprocating and continuous rotary nickel-titanium instruments following root canal retreatment.

    PubMed

    Kalyoncuoğlu, Elif; Keskin, Cangül; Uzun, İsmail; Bengü, Aydın S; Guler, Buğra

    2016-01-01

    This study aimed to evaluate superficial defects and the composition of Reciproc R25 and ProTaper Retreatment file systems (Dentsply Maillefer, Ballaigues, Switzerland) used for retreatment. A total of 100 maxillary incisor teeth were randomly divided into the following two groups: Reciproc R25 (n = 25) and ProTaper Retreatment instrument (n = 75) groups. The nickel-titanium (Ni-Ti) compositions of the files before and after use were analyzed using energy dispersive X-ray spectrophotometry (EDX). Chi-square, Mann-Whitney U, and Kruskal-Wallis tests were used to analyze the data. ProTaper Retreatment instrument group showed a significantly higher number of defects than the Reciproc group (P < 0.05). No instrument fracture was detected. The presence of debris was observed in both groups before use, although the level was significantly higher in the ProTaper Retreatment group, which consisted of metals (P < 0.05). There was no significant difference between new and used instruments with regard to Ni-Ti composition (P < 0.05). EDX analysis showed that both the Reciproc and ProTaper Retreatment instruments had a Ni-Ti composition that was within the standards specified by the American Society of Testing and Materials. This study confirmed the use of both the Reciproc R25 file and ProTaper Retreatment file system for root canal filling removal in straight root canals as a safe procedure. (J Oral Sci 58, 401-406, 2016). PMID:27665980

  7. Retreatment of recanalized aneurysms after Y-stent-assisted coil embolization with double enterprise stents: case report and systematic review of the literature.

    PubMed

    Kono, Kenichi; Shintani, Aki; Terada, Tomoaki

    2014-01-01

    It is necessary to consider possibility of recanalization and retreatment after coil embolization for cerebral aneurysms. There is concern that retreatment for recanalized aneurysms after Y-stent-assisted coil embolization may be difficult because of double stents, especially in Y-stents with double closed-cell stents owing to narrowed structures. However, no detailed reports of retreatment after Y-stent have been reported. Between July 2010 and June 2013, we treated four aneurysms with Y-stent-assisted coil embolization using Enterprise closed-cell stents. Recanalization occurred in one case (25%), and retreatment was performed. We easily navigated a microcatheter into the target portions of the aneurysm through the Y-stent and occluded the aneurysm with coils. Additionally, by systematically searching in PubMed, we found 105 cases of Y-stent-assisted coil embolization using Enterprise stents or Neuroform stents with more than 6 months of follow-up. Among them, retreatment was performed in 10 cases (9.5%). There were no significant differences in retreatment rates among different stent combinations (P=0.91; Fisher's exact test). In conclusion, navigation of a microcatheter into the aneurysm through the Y-stent with double Enterprise stents was feasible, and retreatment rates after Y-stent-assisted coiling may not depend on stent combinations.

  8. Ocean-driven thinning enhances iceberg calving and retreat of Antarctic ice shelves

    PubMed Central

    Liu, Yan; Moore, John C.; Cheng, Xiao; Gladstone, Rupert M.; Bassis, Jeremy N.; Liu, Hongxing; Wen, Jiahong; Hui, Fengming

    2015-01-01

    Iceberg calving from all Antarctic ice shelves has never been directly measured, despite playing a crucial role in ice sheet mass balance. Rapid changes to iceberg calving naturally arise from the sporadic detachment of large tabular bergs but can also be triggered by climate forcing. Here we provide a direct empirical estimate of mass loss due to iceberg calving and melting from Antarctic ice shelves. We find that between 2005 and 2011, the total mass loss due to iceberg calving of 755 ± 24 gigatonnes per year (Gt/y) is only half the total loss due to basal melt of 1516 ± 106 Gt/y. However, we observe widespread retreat of ice shelves that are currently thinning. Net mass loss due to iceberg calving for these ice shelves (302 ± 27 Gt/y) is comparable in magnitude to net mass loss due to basal melt (312 ± 14 Gt/y). Moreover, we find that iceberg calving from these decaying ice shelves is dominated by frequent calving events, which are distinct from the less frequent detachment of isolated tabular icebergs associated with ice shelves in neutral or positive mass balance regimes. Our results suggest that thinning associated with ocean-driven increased basal melt can trigger increased iceberg calving, implying that iceberg calving may play an overlooked role in the demise of shrinking ice shelves, and is more sensitive to ocean forcing than expected from steady state calving estimates. PMID:25733856

  9. Constraints on the retreat from a welfare-orientated approach to public health care in Malaysia.

    PubMed

    Barraclough, S

    1999-04-01

    Both in its articulation of values and through incremental changes, the Malaysian government has signalled a change in attitude towards the welfare approach which had hitherto characterized public health care policy. This change envisions an end to reliance upon the state for the provision and financing of health services and the fostering of a system of family-based welfare. In the future citizens should finance their own health care through savings, insurance or as part of their terms of employment. While the state will still accept a degree of responsibility for those unable to pay for their health care, it wishes to share this burden with the corporate sector and non-government organizations as part of a national policy of the 'Caring Society'. In this article the retreat from a commitment to a welfare model of public health care is documented and some of the serious obstacles to such a policy are discussed. It is concluded that the government's aspirations for reforming the welfare model will need to be tempered by both practical and political considerations. Moreover, the socio-economic consequences of the Asian currency crisis of 1997 are likely to increase the need for government welfare action. PMID:10387810

  10. Factors in Rapid Coastal Retreat: Comparing Two New Datasets for Alaska's Arctic Coast

    NASA Astrophysics Data System (ADS)

    Higman, B. M.; Gibbs, A.; Richmond, B. M.

    2014-12-01

    Dramatic coastal change dominated by erosion and retreat is widespread on arctic coasts, and two extensive new datasets in Alaska's Arctic provide insight into the extent and character of this change. ShoreZone data provides detailed categorical descriptions of physical coastal morphology for about 6000 km of Beaufort and Chukchi Seas coast. A USGS National Assessment of Shoreline Change (NASC) study documents coastal change rates at 50 meter intervals along about 1300 km of coast distributed between the Canadian Border and Icy Cape, almost entirely within the ShoreZone study area. Descriptive ShoreZone data provides a framework for better understanding coastal environments and their importance to change rates. We are applying a new method for clustering and comparing ShoreZone units to generate subsets of NASC coastal change rates with similar coastal morphology, and mapping areas outside the NASC study that show similarity to areas with documented high rates of erosion or accretion. Joint analysis of these two datasets provides insight into the processes that control coastal change, and a starting point for understanding how climate change is transforming Arctic coasts.

  11. Sea ice retreat alters the biogeography of the Bering Sea continental shelf.

    PubMed

    Mueter, Franz J; Litzow, Michael A

    2008-03-01

    Seasonal ice cover creates a pool of cold bottom water on the eastern Bering Sea continental shelf each winter. The southern edge of this cold pool, which defines the ecotone between arctic and subarctic communities, has retreated approximately 230 km northward since the early 1980s. Bottom trawl surveys of fish and invertebrates in the southeastern Bering Sea (1982-2006) show a coincident reorganization in community composition by latitude. Survey catches show community-wide northward distribution shifts, and the area formerly covered by the cold pool has seen increases in total biomass, species richness, and average trophic level as subarctic fauna have colonized newly favorable habitats. Warming climate has immediate management implications, as 57% of variability in commercial snow crab (Chionoecetes opilio) catch is explained by winter sea ice extent. Several measures of community distribution and structure show linear relationships with bottom temperature, suggesting warming climate as the primary cause of changing biogeography. However, residual variability in distribution not explained by climate shows a strong temporal trend, suggesting that internal community dynamics also contribute to changing biogeography. Variability among taxa in their response to temperature was not explained by commercial status or life history traits, suggesting that species-specific responses to future warming will be difficult to predict.

  12. Future increases in Arctic precipitation linked to local evaporation and sea-ice retreat.

    PubMed

    Bintanja, R; Selten, F M

    2014-05-22

    Precipitation changes projected for the end of the twenty-first century show an increase of more than 50 per cent in the Arctic regions. This marked increase, which is among the highest globally, has previously been attributed primarily to enhanced poleward moisture transport from lower latitudes. Here we use state-of-the-art global climate models to show that the projected increases in Arctic precipitation over the twenty-first century, which peak in late autumn and winter, are instead due mainly to strongly intensified local surface evaporation (maximum in winter), and only to a lesser degree due to enhanced moisture inflow from lower latitudes (maximum in late summer and autumn). Moreover, we show that the enhanced surface evaporation results mainly from retreating winter sea ice, signalling an amplified Arctic hydrological cycle. This demonstrates that increases in Arctic precipitation are firmly linked to Arctic warming and sea-ice decline. As a result, the Arctic mean precipitation sensitivity (4.5 per cent increase per degree of temperature warming) is much larger than the global value (1.6 to 1.9 per cent per kelvin). The associated seasonally varying increase in Arctic precipitation is likely to increase river discharge and snowfall over ice sheets (thereby affecting global sea level), and could even affect global climate through freshening of the Arctic Ocean and subsequent modulations of the Atlantic meridional overturning circulation. PMID:24805239

  13. The Retreat from Locative Overgeneralisation Errors: A Novel Verb Grammaticality Judgment Study

    PubMed Central

    Bidgood, Amy; Ambridge, Ben; Pine, Julian M.; Rowland, Caroline F.

    2014-01-01

    Whilst some locative verbs alternate between the ground- and figure-locative constructions (e.g. Lisa sprayed the flowers with water/Lisa sprayed water onto the flowers), others are restricted to one construction or the other (e.g. *Lisa filled water into the cup/*Lisa poured the cup with water). The present study investigated two proposals for how learners (aged 5–6, 9–10 and adults) acquire this restriction, using a novel-verb-learning grammaticality-judgment paradigm. In support of the semantic verb class hypothesis, participants in all age groups used the semantic properties of novel verbs to determine the locative constructions (ground/figure/both) in which they could and could not appear. In support of the frequency hypothesis, participants' tolerance of overgeneralisation errors decreased with each increasing level of verb frequency (novel/low/high). These results underline the need to develop an integrated account of the roles of semantics and frequency in the retreat from argument structure overgeneralisation. PMID:24830412

  14. Particularism and the retreat from theory in the archaeology of agricultural origins.

    PubMed

    Gremillion, Kristen J; Barton, Loukas; Piperno, Dolores R

    2014-04-29

    The introduction of new analytic methods and expansion of research into previously untapped regions have greatly increased the scale and resolution of data relevant to the origins of agriculture (OA). As a result, the recognition of varied historical pathways to agriculture and the continuum of management strategies have complicated the search for general explanations for the transition to food production. In this environment, higher-level theoretical frameworks are sometimes rejected on the grounds that they force conclusions that are incompatible with real-world variability. Some of those who take this position argue instead that OA should be explained in terms of local and historically contingent factors. This retreat from theory in favor of particularism is based on the faulty beliefs that complex phenomena such as agricultural origins demand equally complex explanations and that explanation is possible in the absence of theoretically based assumptions. The same scholars who are suspicious of generalization are reluctant to embrace evolutionary approaches to human behavior on the grounds that they are ahistorical, overly simplistic, and dismissive of agency and intent. We argue that these criticisms are misplaced and explain why a coherent theory of human behavior that acknowledges its evolutionary history is essential to advancing understanding of OA. Continued progress depends on the integration of human behavior and culture into the emerging synthesis of evolutionary developmental biology that informs contemporary research into plant and animal domestication.

  15. Future increases in Arctic precipitation linked to local evaporation and sea-ice retreat.

    PubMed

    Bintanja, R; Selten, F M

    2014-05-22

    Precipitation changes projected for the end of the twenty-first century show an increase of more than 50 per cent in the Arctic regions. This marked increase, which is among the highest globally, has previously been attributed primarily to enhanced poleward moisture transport from lower latitudes. Here we use state-of-the-art global climate models to show that the projected increases in Arctic precipitation over the twenty-first century, which peak in late autumn and winter, are instead due mainly to strongly intensified local surface evaporation (maximum in winter), and only to a lesser degree due to enhanced moisture inflow from lower latitudes (maximum in late summer and autumn). Moreover, we show that the enhanced surface evaporation results mainly from retreating winter sea ice, signalling an amplified Arctic hydrological cycle. This demonstrates that increases in Arctic precipitation are firmly linked to Arctic warming and sea-ice decline. As a result, the Arctic mean precipitation sensitivity (4.5 per cent increase per degree of temperature warming) is much larger than the global value (1.6 to 1.9 per cent per kelvin). The associated seasonally varying increase in Arctic precipitation is likely to increase river discharge and snowfall over ice sheets (thereby affecting global sea level), and could even affect global climate through freshening of the Arctic Ocean and subsequent modulations of the Atlantic meridional overturning circulation.

  16. Particularism and the retreat from theory in the archaeology of agricultural origins

    PubMed Central

    Gremillion, Kristen J.; Barton, Loukas; Piperno, Dolores R.

    2014-01-01

    The introduction of new analytic methods and expansion of research into previously untapped regions have greatly increased the scale and resolution of data relevant to the origins of agriculture (OA). As a result, the recognition of varied historical pathways to agriculture and the continuum of management strategies have complicated the search for general explanations for the transition to food production. In this environment, higher-level theoretical frameworks are sometimes rejected on the grounds that they force conclusions that are incompatible with real-world variability. Some of those who take this position argue instead that OA should be explained in terms of local and historically contingent factors. This retreat from theory in favor of particularism is based on the faulty beliefs that complex phenomena such as agricultural origins demand equally complex explanations and that explanation is possible in the absence of theoretically based assumptions. The same scholars who are suspicious of generalization are reluctant to embrace evolutionary approaches to human behavior on the grounds that they are ahistorical, overly simplistic, and dismissive of agency and intent. We argue that these criticisms are misplaced and explain why a coherent theory of human behavior that acknowledges its evolutionary history is essential to advancing understanding of OA. Continued progress depends on the integration of human behavior and culture into the emerging synthesis of evolutionary developmental biology that informs contemporary research into plant and animal domestication. PMID:24753601

  17. Hydrostatic pressure effect on micro air bubbles deposited on surfaces with a retreating tip.

    PubMed

    Huynh, So Hung; Wang, Jingming; Yu, Yang; Ng, Tuck Wah

    2014-06-01

    The effect of hydrostatic pressure on 6 μL air bubbles formed on micropillar structured PDMS and silicone surfaces using a 2 mm diameter stainless steel tip retreated at 1 mm/s was investigated. Dimensional analysis of the tip retraction process showed the experiments to be conducted in the condition where fluid inertial forces are comparable in magnitude with surface tension forces, while viscous forces were lower. Larger bubbles could be left behind on the structured PDMS surface. For hydrostatic pressures in excess of 20 mm H2O (196 Pa), the volume of bubble deposited was found to decrease progressively with pressure increase. The differences in width of the deposited bubbles (in contact with the substrate) were significant at any particular pressure but marginal in height. The attainable height before rupture reduced with pressure increase, thereby accounting for the reducing dispensed volume characteristic. On structured PDMS, the gaseous bridge width (in contact with the substrate) was invariant with tip retraction, while on silicone it was initially reducing before becoming invariant in the lead up to rupture. With silicone, hence, reductions in the contact width and height were both responsible for reduced volumes with pressure increase. Increased hydrostatic pressure was also found to restrict the growth in contact width on silicone during the stage when air was injected in through the tip. The ability to effect bubble size in such a simple manner may already be harnessed in nature and suggests possibilities in technological applications.

  18. Oceanic Forcing of Ice-Sheet Retreat: West Antarctica and More

    NASA Astrophysics Data System (ADS)

    Alley, Richard B.; Anandakrishnan, Sridhar; Christianson, Knut; Horgan, Huw J.; Muto, Atsu; Parizek, Byron R.; Pollard, David; Walker, Ryan T.

    2015-05-01

    Ocean-ice interactions have exerted primary control on the Antarctic Ice Sheet and parts of the Greenland Ice Sheet, and will continue to do so in the near future, especially through melting of ice shelves and calving cliffs. Retreat in response to increasing marine melting typically exhibits threshold behavior, with little change for forcing below the threshold but a rapid, possibly delayed shift to a reduced state once the threshold is exceeded. For Thwaites Glacier, West Antarctica, the threshold may already have been exceeded, although rapid change may be delayed by centuries, and the reduced state will likely involve loss of most of the West Antarctic Ice Sheet, causing >3 m of sea-level rise. Because of shortcomings in physical understanding and available data, uncertainty persists about this threshold and the subsequent rate of change. Although sea-level histories and physical understanding allow the possibility that ice-sheet response could be quite fast, no strong constraints are yet available on the worst-case scenario. Recent work also suggests that the Greenland and East Antarctic Ice Sheets share some of the same vulnerabilities to shrinkage from marine influence.

  19. Runoff Modelling of the Khumbu Glacier, Nepal: Incorporating Debris Cover and Retreat Dynamics.

    NASA Astrophysics Data System (ADS)

    Douglas, James; Huss, Matthias; Jones, Julie; Swift, Darrel; Salerno, Franco

    2016-04-01

    Detailed studies on the future evolution and runoff of glaciers in high mountain Asia are scarce considering the region is so reliant on on this essential water source. This study adapts a model well-proven in the European Alps, the Glacier Evolution and Runoff Model (GERM), to simulate the behaviour of the Khumbu glacier, Nepal. GERM calculates glacier mass balance and runoff using a distributed temperature index model which has been modified such that the unique dynamics of debris covered glaciers, namely stagnation, thinning, and melt-inhibiting debris surfaces, are incorporated. Debris thickness is derived from both remote sensing and model based approaches allowing a suite of experiments to be conducted using various levels of debris cover. The model is driven by CORDEX-South Asia regional climate model (RCM) simulations, bias corrected using a quantile mapping technique based on in-situ data from the Pyramid meteorological station. Here, results are presented showing the retreat of the Khumbu glacier and the corresponding changes for annual and seasonal discharge until 2100, using varying melt parameters and debris thicknesses to assess the impact of debris cover on glacier evolution and runoff.

  20. Constraints on the retreat from a welfare-orientated approach to public health care in Malaysia.

    PubMed

    Barraclough, S

    1999-04-01

    Both in its articulation of values and through incremental changes, the Malaysian government has signalled a change in attitude towards the welfare approach which had hitherto characterized public health care policy. This change envisions an end to reliance upon the state for the provision and financing of health services and the fostering of a system of family-based welfare. In the future citizens should finance their own health care through savings, insurance or as part of their terms of employment. While the state will still accept a degree of responsibility for those unable to pay for their health care, it wishes to share this burden with the corporate sector and non-government organizations as part of a national policy of the 'Caring Society'. In this article the retreat from a commitment to a welfare model of public health care is documented and some of the serious obstacles to such a policy are discussed. It is concluded that the government's aspirations for reforming the welfare model will need to be tempered by both practical and political considerations. Moreover, the socio-economic consequences of the Asian currency crisis of 1997 are likely to increase the need for government welfare action.

  1. Modelling weathering induced retreat of c-φ cliffs with limited tensile strength

    NASA Astrophysics Data System (ADS)

    Voulgari, C.

    2015-09-01

    Natural cliffs subject to weathering induced retreat are typically made of hard soils and / or weak rocks exhibiting limited tensile strength. In this paper, the morphologic evolution of uniform c, φ slopes subject to weathering is investigated for a range of values of tensile strengths employing the limit analysis upper bound method. This paper extends the analytical framework set up in [1, 2] by accounting for the limited tensile strength of the ground which was previously disregarded. The solutions were obtained by employing the kinematic method of limit analysis providing rigorous upper bounds to the true collapse values. The inclusion of tension cracks leads to modified analytical expressions of the energy balance equation (the balance between external work and dissipated energy) and as a consequence, of the function whose minimum provides the solution in terms of failure mechanisms and associated values of soil strength. Pre-existing cracks are considered, as well as cracks that form as part of the failure mechanism. It turns out that the presence of tension cracks may significantly alter the size of each landslide contributing to the retrogression of the slope. Results in the form of dimensionless ready-to-use charts are produced for any value of engineering interest of friction angle and slope inclination for the case of dry cracks. Moreover, upper bounds for values not included in the charts can be achieved either by interpolation from the charts or by running the minimisation of the analytical functions provided in the paper.

  2. Remotely-Sensed Glacial Velocities: Mt. Shasta Advance vs. Sierra Nevada Retreat

    NASA Astrophysics Data System (ADS)

    Thompson, J. A.; Bookhagen, B.; Burbank, D. W.

    2008-12-01

    Monitoring changes in alpine glaciers is crucial to understanding the impacts of global climate change because alpine glacier systems respond quickly to changes in the earth´s climate. The glaciers of the Sierra Nevada and southern Cascades are of particular interest because they provide a major water reservoir to the state of California. Oddly, while most glaciers worldwide (including in the Sierra Nevada) are retreating, glaciers in northern California are advancing, and examining differences between these two locations will help resolve this paradox. Whereas previous studies have mapped the spatial extents of glaciers from aerial and satellite imagery, this study utilizes glacial velocities as a monitoring tool to examine the differences of the glaciers in the Sierra Nevada and on Mount Shasta. Using the program COSI-Corr in ENVI, horizontal surface ice flow velocities are calculated at the subpixel level from a time-series of co-registered, orthorectified, and correlated, late-summer satellite imagery. Through a combination of 15-meter Advanced Spaceborne Thermal Emission Radiometer (ASTER) and 5-meter SPOT imagery, orthorectified using a 15-meter resampled Shuttle Radar Topographic Mission (SRTM) digital elevation model (DEM), glacial velocities are derived on major glaciers on Mount Shasta and in the Palisades of the Sierra Nevada for 2000-2008. This study demonstrates the utility of combining various types of remote sensing imagery to create a complete time record, and from this record derive glacial velocities for use in monitoring climate change effectively.

  3. Arctic cyclone water vapor isotopes support past sea ice retreat recorded in Greenland ice

    PubMed Central

    Klein, Eric S.; Cherry, J. E.; Young, J.; Noone, D.; Leffler, A. J.; Welker, J. M.

    2015-01-01

    Rapid Arctic warming is associated with important water cycle changes: sea ice loss, increasing atmospheric humidity, permafrost thaw, and water-induced ecosystem changes. Understanding these complex modern processes is critical to interpreting past hydrologic changes preserved in paleoclimate records and predicting future Arctic changes. Cyclones are a prevalent Arctic feature and water vapor isotope ratios during these events provide insights into modern hydrologic processes that help explain past changes to the Arctic water cycle. Here we present continuous measurements of water vapor isotope ratios (δ18O, δ2H, d-excess) in Arctic Alaska from a 2013 cyclone. This cyclone resulted in a sharp d-excess decrease and disproportional δ18O enrichment, indicative of a higher humidity open Arctic Ocean water vapor source. Past transitions to warmer climates inferred from Greenland ice core records also reveal sharp decreases in d-excess, hypothesized to represent reduced sea ice extent and an increase in oceanic moisture source to Greenland Ice Sheet precipitation. Thus, measurements of water vapor isotope ratios during an Arctic cyclone provide a critical processed-based explanation, and the first direct confirmation, of relationships previously assumed to govern water isotope ratios during sea ice retreat and increased input of northern ocean moisture into the Arctic water cycle. PMID:26023728

  4. Light-intensity modulator withstands high heat fluxes

    NASA Technical Reports Server (NTRS)

    Maples, H. G.; Strass, H. K.

    1966-01-01

    Mechanism modulates and controls the intensity of luminous radiation in light beams associated with high-intensity heat flux. This modulator incorporates two fluid-cooled, externally grooved, contracting metal cylinders which when rotated about their longitudinal axes present a circular aperture of varying size depending on the degree of rotation.

  5. Longitudinal Stern-Gerlach

    NASA Astrophysics Data System (ADS)

    Higinbotham, Douglas

    2006-11-01

    In 1922 Otto Stern and Walther Gerlach split a beam of silver atoms using a transverse gradient field. This experiment, which lead to the understanding that electrons have intrinsic spin, oddly enough does not work for free electrons due to the interplay between the Lorentz force and Heisenberg uncertainly principle. Recent calculations, Phys. Rev. Lett. 79 (1997) 4517 and Phys. Rev. Lett. 86 (2001) 4508, have shown that a dismissed idea of L. Brillouin from 1928 to use a longitudinal gradient field to minimize the effect of the Lorentz force may in fact be possible. The history of the Stern-Gerlach device will be presented along with the revived ideas for separating a beam of free electrons into its two spin states.

  6. Strong paleoseismic manifestations in the south Baltic Sea basin, Kaliningrad city area, related to the retreat of the Fennoscandian Ice Sheet

    NASA Astrophysics Data System (ADS)

    Rogozhin, Evgeny; Ovsuchenko, Alexander; Andreeva, Nadezhda; Buchroithner, Manfred; Rogozhina, Irina; Stroeven, Arjen P.; Osei Tutu, Anthony; Seguinot, Julien; Bernales, Jorge; Klemann, Volker; Hagedoorn, Jan M.

    2014-05-01

    Evidence of Mw >7-8 paleo-earthquakes accompanying final deglaciation across Fennoscandia and North America indicates enhanced seismicity close to the retreating margins of former ice sheets. Many of these high-latitude continental regions are currently characterized by moderate seismicity with typical magnitudes of Mw≡4-5. The relation between modern seismicity and former glaciations through ongoing isostatic adjustment is, however, a subject of considerable debate. Here we report and interpret new data on paleo- and contemporary earthquakes in one of the least studied regions formerly covered by the Fennoscandian Ice Sheet (FIS), namely the Kaliningrad area. According to paleoseismic evidence, an earthquake with a magnitude of Mw ≥ 7 occurred in this region about 11±0.5 ka ago. The age of the resulting paleoseismic ruptures (landslides, marks of liquefaction, seismites, close-to-fault folding) was determined by radiocarbon dating. Comparison with the reconstructed extent of FIS from glacial geomorphology reveals that the timing of this strong event, within dating uncertainty, coincides with the timing of local deglaciation. In this period, the ice margin across the south-eastern Baltic Sea region had retreated to allow, in succession, the Yoldia Sea, Ancylus Lake and the Littorina Sea to emerge. Because sediments previously covered by ice became oversaturated with water from the Yoldia Sea, the seismic shaking of the Mw ≥ 7 earthquake produced gravitational ruptures, which were found during our field investigations. Several seismic events have been registered using instrumental observations in the 20th and early 21st centuries. The latest earthquake occurred in Kaliningrad in 2004 with Mw 4.8, following a foreshock of Mw 4.6. The epicenter area was studied using seismotectonic and seismological methods immediately after the event. We identified some active faults responsible for the generation of the 2004 events, revealing that several moderate seismic

  7. Digital Longitudinal Tomosynthesis

    NASA Astrophysics Data System (ADS)

    Rimkus, Daniel Steven

    1985-12-01

    The purpose of this dissertation was to investigate the clinical utility of digital longitudinal tomosynthesis in radiology. By acquiring a finite group of digital images during a longitudinal tomographic exposure, and processing these images, tomographic planes, other than the fulcrum plane, can be reconstructed. This process is now termed "tomosynthesis". A prototype system utilizing this technique was developed. Both phantom and patient studies were done with this system. The phantom studies were evaluated by subjective, visual criterion and by quantitative analysis of edge sharpness and noise in the reconstructions. Two groups of patients and one volunteer were studied. The first patient group consisted of 8 patients undergoing intravenous urography (IVU). These patients had digital tomography and film tomography of the abdomen. The second patient group consisted of 4 patients with lung cancer admitted to the hospital for laser resection of endobronchial tumor. These patients had mediastinal digital tomograms to evaluate the trachea and mainstem bronchi. The knee of one volunteer was imaged by film tomography and digital tomography. The results of the phantom studies showed that the digital reconstructions accurately produced images of the desired planes. The edge sharpness of the reconstructions approached that of the acquired images. Adequate reconstructions were achieved with as few as 5 images acquired during the exposure, with the quality of the reconstructions improving as the number of images acquired increased. The IVU patients' digital studies had less contrast and spatial resolution than the film tomograms. The single renal lesion visible on the film tomograms was also visible in the digital images. The digital mediastinal studies were felt by several radiologists to be superior to a standard chest xray in evaluating the airways. The digital images of the volunteer's knee showed many of the same anatomic features as the film tomogram, but the digital

  8. Creating a specialist protein resource network: a meeting report for the protein bioinformatics and community resources retreat.

    PubMed

    Babbitt, Patricia C; Bagos, Pantelis G; Bairoch, Amos; Bateman, Alex; Chatonnet, Arnaud; Chen, Mark Jinan; Craik, David J; Finn, Robert D; Gloriam, David; Haft, Daniel H; Henrissat, Bernard; Holliday, Gemma L; Isberg, Vignir; Kaas, Quentin; Landsman, David; Lenfant, Nicolas; Manning, Gerard; Nagano, Nozomi; Srinivasan, Narayanaswamy; O'Donovan, Claire; Pruitt, Kim D; Sowdhamini, Ramanathan; Rawlings, Neil D; Saier, Milton H; Sharman, Joanna L; Spedding, Michael; Tsirigos, Konstantinos D; Vastermark, Ake; Vriend, Gerrit

    2015-01-01

    During 11-12 August 2014, a Protein Bioinformatics and Community Resources Retreat was held at the Wellcome Trust Genome Campus in Hinxton, UK. This meeting brought together the principal investigators of several specialized protein resources (such as CAZy, TCDB and MEROPS) as well as those from protein databases from the large Bioinformatics centres (including UniProt and RefSeq). The retreat was divided into five sessions: (1) key challenges, (2) the databases represented, (3) best practices for maintenance and curation, (4) information flow to and from large data centers and (5) communication and funding. An important outcome of this meeting was the creation of a Specialist Protein Resource Network that we believe will improve coordination of the activities of its member resources. We invite further protein database resources to join the network and continue the dialogue. PMID:26284514

  9. Characteristics of recessional moraines at a temperate glacier in SE Iceland: Insights into patterns, rates and drivers of glacier retreat

    NASA Astrophysics Data System (ADS)

    Chandler, Benjamin M. P.; Evans, David J. A.; Roberts, David H.

    2016-03-01

    Icelandic glaciers are sensitive to climate variability on short-term timescales owing to their North Atlantic maritime setting, and have been undergoing ice-marginal retreat since the mid-1990s. Recent patterns, rates and drivers of ice-frontal retreat at Skálafellsjökull, SE Iceland, are examined using small-scale recessional moraines as a geomorphological proxy. These small-scale recessional moraines exhibit distinctive sawtooth planform geometries, and are constructed by a range of genetic processes associated with minor ice-margin re-advance, including (i) combined push/squeeze mechanisms, (ii) bulldozing of pre-existing proglacial material, and (iii) submarginal freeze-on. Remote-sensing investigations and lichenometric dating highlight sequences of annually-formed recessional moraines on the northern and central parts of the foreland. Conversely, moraines are forming on a sub-annual timescale at the southeastern Skálafellsjökull margin. Using annual moraine spacing as a proxy for annual ice-margin retreat rates (IMRRs), we demonstrate that prominent periods of glacier retreat at Skálafellsjökull are coincident with those at other Icelandic outlet glaciers, as well as those identified at Greenlandic outlet glaciers. Analysis of IMRRs and climate data suggests summer air temperature, sea surface temperature and the North Atlantic Oscillation have an influence on IMRRs at Skálafellsjökull, with the glacier appearing to be most sensitive to summer air temperature. On the basis of further climate data analyses, we hypothesise that sea surface temperature may drive air temperature changes in the North Atlantic region, which in turn forces IMRRs. The increase in sea surface temperature over recent decades may link to atmospheric-driven variations in North Atlantic subpolar gyre dynamics.

  10. Predicting the retreat and migration of tidal forests along the northern Gulf of Mexico under sea-level rise

    USGS Publications Warehouse

    Doyle, T.W.; Krauss, K.W.; Conner, W.H.; From, A.S.

    2010-01-01

    Tidal freshwater forests in coastal regions of the southeastern United States are undergoing dieback and retreat from increasing tidal inundation and saltwater intrusion attributed to climate variability and sea-level rise. In many areas, tidal saltwater forests (mangroves) contrastingly are expanding landward in subtropical coastal reaches succeeding freshwater marsh and forest zones. Hydrological characteristics of these low-relief coastal forests in intertidal settings are dictated by the influence of tidal and freshwater forcing. In this paper, we describe the application of the Sea Level Over Proportional Elevation (SLOPE) model to predict coastal forest retreat and migration from projected sea-level rise based on a proxy relationship of saltmarsh/mangrove area and tidal range. The SLOPE model assumes that the sum area of saltmarsh/mangrove habitat along any given coastal reach is determined by the slope of the landform and vertical tide forcing. Model results indicated that saltmarsh and mangrove migration from sea-level rise will vary by county and watershed but greater in western Gulf States than in the eastern Gulf States where millions of hectares of coastal forest will be displaced over the next century with a near meter rise in relative sea level alone. Substantial losses of coastal forests will also occur in the eastern Gulf but mangrove forests in subtropical zones of Florida are expected to replace retreating freshwater forest and affect regional biodiversity. Accelerated global eustacy from climate change will compound the degree of predicted retreat and migration of coastal forests with expected implications for ecosystem management of State and Federal lands in the absence of adaptive coastal management.

  11. Advancing-side directivity and retreating-side interactions of model rotor blade-vortex interaction noise

    NASA Technical Reports Server (NTRS)

    Martin, R. M.; Splettstoesser, W. R.; Elliott, J. W.; Schultz, K.-J.

    1988-01-01

    Acoustic data are presented from a 40 percent scale model of the four-bladed BO-105 helicopter main rotor, tested in a large aerodynamic wind tunnel. Rotor blade-vortex interaction (BVI) noise data in the low-speed flight range were acquired using a traversing in-flow microphone array. Acoustic results presented are used to assess the acoustic far field of BVI noise, to map the directivity and temporal characteristics of BVI impulsive noise, and to show the existence of retreating-side BVI signals. The characterics of the acoustic radiation patterns, which can often be strongly focused, are found to be very dependent on rotor operating condition. The acoustic signals exhibit multiple blade-vortex interactions per blade with broad impulsive content at lower speeds, while at higher speeds, they exhibit fewer interactions per blade, with much sharper, higher amplitude acoustic signals. Moderate-amplitude BVI acoustic signals measured under the aft retreating quadrant of the rotor are shown to originate from the retreating side of the rotor.

  12. Preemption versus Entrenchment: Towards a Construction-General Solution to the Problem of the Retreat from Verb Argument Structure Overgeneralization

    PubMed Central

    Ambridge, Ben; Bidgood, Amy; Twomey, Katherine E.; Pine, Julian M.; Rowland, Caroline F.; Freudenthal, Daniel

    2015-01-01

    Participants aged 5;2-6;8, 9;2-10;6 and 18;1-22;2 (72 at each age) rated verb argument structure overgeneralization errors (e.g., *Daddy giggled the baby) using a five-point scale. The study was designed to investigate the feasibility of two proposed construction-general solutions to the question of how children retreat from, or avoid, such errors. No support was found for the prediction of the preemption hypothesis that the greater the frequency of the verb in the single most nearly synonymous construction (for this example, the periphrastic causative; e.g., Daddy made the baby giggle), the lower the acceptability of the error. Support was found, however, for the prediction of the entrenchment hypothesis that the greater the overall frequency of the verb, regardless of construction, the lower the acceptability of the error, at least for the two older groups. Thus while entrenchment appears to be a robust solution to the problem of the retreat from error, and one that generalizes across different error types, we did not find evidence that this is the case for preemption. The implication is that the solution to the retreat from error lies not with specialized mechanisms, but rather in a probabilistic process of construction competition. PMID:25919003

  13. Evidence of macroalgal colonization on newly ice-free areas following glacial retreat in Potter Cove (South Shetland Islands), Antarctica.

    PubMed

    Quartino, María Liliana; Deregibus, Dolores; Campana, Gabriela Laura; Latorre, Gustavo Edgar Juan; Momo, Fernando Roberto

    2013-01-01

    Climate warming has been related to glacial retreat along the Western Antarctic Peninsula. Over the last years, a visible melting of Fourcade Glacier (Potter Cove, South Shetland Islands) has exposed newly ice-free hard bottom areas available for benthic colonization. However, ice melting produces a reduction of light penetration due to an increase of sediment input and higher ice impact. Seventeen years ago, the coastal sites close to the glacier cliffs were devoid of macroalgae. Are the newly ice-free areas suitable for macroalgal colonization? To tackle this question, underwater video transects were performed at six newly ice-free areas with different degree of glacial influence. Macroalgae were found in all sites, even in close proximity to the retreating glacier. We can show that: 1. The complexity of the macroalgal community is positively correlated to the elapsed time from the ice retreat, 2. Algae development depends on the optical conditions and the sediment input in the water column; some species are limited by light availability, 3. Macroalgal colonization is negatively affected by the ice disturbance, 4. The colonization is determined by the size and type of substrate and by the slope of the bottom. As macroalgae are probably one of the main energy sources for the benthos, an expansion of the macroalgal distribution can be expected to affect the matter and energy fluxes in Potter Cove ecosystem.

  14. Temporal filtering of longitudinal brain magnetic resonance images for consistent segmentation.

    PubMed

    Roy, Snehashis; Carass, Aaron; Pacheco, Jennifer; Bilgel, Murat; Resnick, Susan M; Prince, Jerry L; Pham, Dzung L

    2016-01-01

    Longitudinal analysis of magnetic resonance images of the human brain provides knowledge of brain changes during both normal aging as well as the progression of many diseases. Previous longitudinal segmentation methods have either ignored temporal information or have incorporated temporal consistency constraints within the algorithm. In this work, we assume that some anatomical brain changes can be explained by temporal transitions in image intensities. Once the images are aligned in the same space, the intensities of each scan at the same voxel constitute a temporal (or 4D) intensity trend at that voxel. Temporal intensity variations due to noise or other artifacts are corrected by a 4D intensity-based filter that smooths the intensity values where appropriate, while preserving real anatomical changes such as atrophy. Here smoothing refers to removal of sudden changes or discontinuities in intensities. Images processed with the 4D filter can be used as a pre-processing step to any segmentation method. We show that such a longitudinal pre-processing step produces robust and consistent longitudinal segmentation results, even when applying 3D segmentation algorithms. We compare with state-of-the-art 4D segmentation algorithms. Specifically, we experimented on three longitudinal datasets containing 4-12 time-points, and showed that the 4D temporal filter is more robust and has more power in distinguishing between healthy subjects and those with dementia, mild cognitive impairment, as well as different phenotypes of multiple sclerosis. PMID:26958465

  15. Temporal filtering of longitudinal brain magnetic resonance images for consistent segmentation

    PubMed Central

    Roy, Snehashis; Carass, Aaron; Pacheco, Jennifer; Bilgel, Murat; Resnick, Susan M.; Prince, Jerry L.; Pham, Dzung L.

    2016-01-01

    Longitudinal analysis of magnetic resonance images of the human brain provides knowledge of brain changes during both normal aging as well as the progression of many diseases. Previous longitudinal segmentation methods have either ignored temporal information or have incorporated temporal consistency constraints within the algorithm. In this work, we assume that some anatomical brain changes can be explained by temporal transitions in image intensities. Once the images are aligned in the same space, the intensities of each scan at the same voxel constitute a temporal (or 4D) intensity trend at that voxel. Temporal intensity variations due to noise or other artifacts are corrected by a 4D intensity-based filter that smooths the intensity values where appropriate, while preserving real anatomical changes such as atrophy. Here smoothing refers to removal of sudden changes or discontinuities in intensities. Images processed with the 4D filter can be used as a pre-processing step to any segmentation method. We show that such a longitudinal pre-processing step produces robust and consistent longitudinal segmentation results, even when applying 3D segmentation algorithms. We compare with state-of-the-art 4D segmentation algorithms. Specifically, we experimented on three longitudinal datasets containing 4–12 time-points, and showed that the 4D temporal filter is more robust and has more power in distinguishing between healthy subjects and those with dementia, mild cognitive impairment, as well as different phenotypes of multiple sclerosis. PMID:26958465

  16. Climate change and glacier retreat in northern Tien Shan (Kazakhstan/Kyrgyzstan) using remote sensing data

    NASA Astrophysics Data System (ADS)

    Bolch, Tobias

    2007-03-01

    This paper presents an analysis of precipitation and temperature trends and a GIS-supported investigation of the related glacier change in the mountain ridges Zailiyskiy and Kungey Alatau, which represent an important part of the northern Tien Shan. The recent glacier coverage was delineated in a semi-automated way using a TM4/TM5 ratio image of a Landsat ETM Scene from the year 1999 and a merged ASTER/SRTM3-DEM. The extent of these glaciers is compared to that of the glaciers in the Soviet Glacier Inventory [UdSSR, Academica Nauk (1966 to 1983). Katalog Lednikov SSSR (in Russian), Gidrometeoizdat. Leningrad], which represents the situation in study area in approx. 1955. Regionalization of temperature and precipitation as well as solar radiation calculation was conducted in order to determine the climate situation at the glaciers. Trend and correlation analysis for the period from 1879 to 2000 at 16 climate stations showed a temperature increase, which have become pronounced since the 1950s. Another strong increase occurred at the beginning of the 1970s and since around 1980, the temperatures have generally stayed at this high level. The trend coefficient was about 0.8 K/100a for the period 1900 to 2000 and about 2.0 K/100a on average for the second half of the last century. The increase was about two times higher than the global average in northern Tien Shan from 1950 until 2000, where the increase was mainly due to temperature rise in autumn and winter. The increase is less pronounced in the mountainous areas, but still obvious. However, the higher temperature increase at the lower stations, located for the most part in cities or larger settlements, may be due in part to increased urbanization. For precipitation, there was a small increase on average, but no clear trend. On the average, the decrease in glacier extent was more than 32% between 1955 and 1999 in the investigated valleys of Zailiyskiy and Kungey Alatau. The glacier retreat was not homogeneous, but

  17. Quantifying Holocene Coastal Retreat From River Morphology in Southern England and Wales

    NASA Astrophysics Data System (ADS)

    Attal, M.; Mudd, S. M.; Hurst, M. D.; Crickmore, B. A.

    2013-12-01

    Southern England and Wales have been undergoing subsidence since the end of the Last Glacial Maximum, with average rates varying between 0.5 and 1.2 mm/yr over the last 10 ka (Shennan and Horton, 2002). Rivers typically respond to subsidence by aggrading (e.g., Ishihara et al., 2012), yet many English and Welsh rivers incise into bedrock at their outlet and exhibit river profiles convexities typical of systems experiencing a drop in base level (e.g., Snyder et al., 2002; Attal et al., 2011). Scientists have proposed that coastal erosion could result in such river morphology (Snyder et al., 2002; Leyland & Darby, 2008, 2009). We combine modelling with topographic analysis of a series of basins along the coast of Southern England and Wales to test whether coastal erosion could explain the occurrence of rivers incising into bedrock at the coast. We further assess whether the distribution of such rivers and the shape of river profiles could be used to constrain amounts of coastal erosion during the Holocene. Within zones characterized by similar lithologies and coastal exposure (i.e. the orientation of the coast and the type of water body it faces), we find that rivers with the smallest basins incise into bedrock at their mouth while rivers with the largest basins experience aggradation. The transition between these two types of basins occurs at a consistent basin size. This signal conforms to model predictions, assuming that the slope of rivers at the coast decreases with increasing basin size. Whereas rivers in basins comprising igneous and/or metamorphic rocks tend to be steeper than rivers flowing on sedimentary bedrock, we find that the critical drainage area does not vary significantly with varying lithology, suggesting that other factors such as spatial variations in coastal retreat exert a stronger control on the spatial distribution of the two types of rivers throughout the study area. Reconstruction of river profiles prior to base level rise allows estimates

  18. Foreland sedimentary record of Andean mountain building during advancing and retreating subduction

    NASA Astrophysics Data System (ADS)

    Horton, Brian K.

    2016-04-01

    -skinned basement inversion with geometrically and kinematically linked thin-skinned thrust structures at shallower levels in the eastern foreland, including well-dated late Miocene growth strata. The mid-Cenozoic hiatus potentially signifies nondeposition during passage of a flexural forebulge or nondeposition during neutral to extensional conditions possibly driven by a transient retreating-slab configuration along the western margin of South America. Similar long-lived stratigraphic gaps are commonly observed in other foreland records of continental convergent margins. It is proposed that Andean orogenesis along the South American convergent margin has long been sensitive to variations in subduction dynamics throughout Mesozoic-Cenozoic time, such that shifts in relative convergence and degree of mechanical coupling along the subduction interface (i.e., transitions between advancing versus retreating modes of subduction) have governed fluctuating contractional, extensional, and neutral conditions. Unclear is whether these various modes affected the entire convergent margin simultaneously due to continental-scale changes (e.g., temporal shifts in plate convergence, absolute motion of upper plate, or mantle wedge circulation) or whether parts of the margin behaved independently due to smaller-scale fluctuations (e.g., spatial variations in the age of the subducted plate, buoyant asperities in the downgoing slab, or asthenospheric anomalies).

  19. Age Estimates of Holocene Glacial Retreat in Lapeyrère Bay, Anvers Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Mead, K. A.; Wellner, J. S.; Rosenheim, B. E.

    2011-12-01

    Lapeyrère Bay is a fjord on the eastern side of Anvers Island, located off the Western Antarctic Peninsula. Anvers island has a maximum elevation of 2400m (comprised of ice overlaying bedrock), and experiences colder temperatures and more precipitation than the South Shetlands, which are ~230km to the north. Two glaciers enter Lapeyrère Bay, one large and vulnerable to avalanching, the Iliad Glacier, and one smaller glacier confined to a northern unnamed cove. Though several research cruises have visited Lapeyrère Bay, very little has been published on the fjord's glacial retreat history or sediment flux. The primary purpose of this study is to reconstruct the glacial retreat and sediment flux histories of Lapeyrère Bay using a SHALDRIL core and standard piston cores for chronology and sedimentary facies analysis, and multibeam swath bathymetry data for identifying seafloor morphological features. Preliminary core data from the proximal northern flank of Lapeyrère Bay show greenish grey sandy mud with scattered pebble and sand lens lithology. A core taken in the distal-most part of the fjord is largely diatomaceous sediment grading into grey silty mud with thin sandy turbidites. Multibeam data has exposed seafloor features including a grounding zone wedge at the entrance of the unnamed cove of northern Lapeyrère Bay, drumlins, glacial lineations, and a glacial outwash fan near the ocean-termination of the Iliad glacier. Additionally, this study seeks to assess the effectiveness of a novel 14C method of dating sediment lacking sufficient calcareous material for carbonate 14C dating. The method being tested is ramped pyrolysis radiocarbon analysis, which dates individual fractions of organic material. It is hypothesized that ramped pyrolysis will improve upon bulk acid insoluble organic material (AIOM) dating, as AIOM can include both autochthonous syndepositionally aged carbon and allochthonous pre-aged carbon, resulting in 14C ages inherently older than the

  20. Monsoon-influenced glacier retreat in the Ladakh Range, Jammu and Kashmir

    NASA Astrophysics Data System (ADS)

    Chudley, Tom; Miles, Evan; Willis, Ian

    2016-04-01

    While the majority of glaciers in the Himalaya-Karakoram mountain chain are receding in response to climate change, stability and even growth is observed in the Karakoram, where glaciers also exhibit widespread surge-type behaviour. Changes in the accumulation regime driven by mid-latitude westerlies could explain such stability relative to the monsoon-fed glaciers of the Himalaya, but a lack of detailed meteorological records presents a challenge for climatological analyses. We therefore analyse glacier changes for an intermediate zone of the HKH to characterise the transition between the substantial retreat of Himalayan glaciers and the surging stability of Karakoram glaciers. Using Landsat imagery, we assess changes in glacier area and length from 1991-2014 across a ˜140 km section of the Ladakh Range, Jammu and Kashmir. Bordering the surging, stable portion of the Karakoram to the north and the Western Himalaya to the southeast, the Ladakh Range represents an important transitional zone to identify the potential role of climatic forcing in explaining differing glacier behaviour across the region. A total of 878 glaciers are semi-automatically identified in 1991, 2002, and 2014 using NDSI (thresholds chosen between 0.30 and 0.45) before being manually corrected. Ice divides and centrelines are automatically derived using an established routine. Total glacier area for the study region is in line with that Randolph Glacier Inventory (RGI) and ˜25% larger than the GLIMS Glacier Database, which is apparently more conservative in assigning ice cover in the accumulation zone. However, the RGI appears notably less successful in identifying glacier termini. Preliminary analysis of glaciers in our study area suggest an overall areal decline of -17.21±7.50% between 1991-2014., a figure more similar to the Zanskar ranges to the south than the Karakoram to the north. No evidence of surge-type behaviour is observed in the study area over this period. Glaciers tend to be

  1. Large-scale retreat and advance of shallow seas in Southeast Asia driven by mantle flow

    NASA Astrophysics Data System (ADS)

    Zahirovic, Sabin; Flament, Nicolas; Dietmar Müller, R.; Seton, Maria; Gurnis, Michael

    2016-04-01

    The Indonesian islands and surrounding region represent one of the most submerged, low-lying continental areas on Earth. Almost half of this region, known as Sundaland, is presently inundated by a shallow sea. The role of mantle convection in driving long-wavelength topography and vertical motion of the lithosphere in this region has largely been ignored when interpreting regional stratigraphic sections, despite a consensus that Southeast Asia presently situated on a "dynamic topography low" resulting from long-term post-Pangea subduction. However, dynamic topography is typically described as a temporally and spatially transient process, implying that Sundaland may have experienced significant vertical motions in the geological past, and thus must be considered when interpreting relative sea level changes and the paleogeographic indicators of advancing and retreating shallow seas. Although the present-day low regional elevation has been attributed to the massive volume of oceanic slabs sinking in the mantle beneath Southeast Asia, a Late Cretaceous to Eocene regional unconformity indicates that shallow seas retreated following regional flooding during the mid-Cretaceous sea level highstand. During the Eocene, less than one fifth of Sundaland was submerged, despite global sea level being ~200 m higher than at present. The regional nature of the switch from marine to terrestrial environments, that is out-of-sync with eustatic sea levels, suggests that broad mantle-driven dynamic uplift may have led to the emergence of Sundaland in the Late Cretaceous and Paleocene. We use numerical forward modelling of plate tectonics and mantle convection, and compare the predicted trends of dynamic topography with evidence from regional paleogeography and eustasy to determine the extent to which mantle-driven vertical motions of the lithosphere have influenced regional basin histories in Southeast Asia. A Late Cretaceous collision of Gondwana-derived terranes with Sundaland choked

  2. Salt marsh retreat induced by wind waves: experiments, field and modeling

    NASA Astrophysics Data System (ADS)

    Solari, L.; Francalanci, S.; Bendoni, M.; Cappietti, L.

    2013-12-01

    Edge erosion of salt marshes due to surface waves and tide forcing is likely the chief mechanism that models marsh boundaries and by which salt marshes in worldwide areas are being lost. To address this problem, an experimental investigation in a laboratory flume and field measurements collected in the lagoon of Venice were conducted to understand the main processes controlling marsh edge retreat with a focus on the erosion mechanisms caused by the impact of wind waves in the case of various tidal levels. A physical model reproducing a salt marsh bank was built inside a long wave current flume where random surface waves have been generated according to a given wave spectrum. The physical model was constructed with the original soil of salt marshes from the Venice Lagoon, while the wave climate was reproduced according to field measurements. In order to reveal the effect of vegetation on bank stability, two identical banks were built but for the inclusion of halophytic plants. A first set of experiments was conducted reproducing only tidal waves, a second set with wind waves superimposed to the tide. A third set o f experiments were aimed to investigate the dynamic impact and transmission of the waves on and within the bank. The following quantities were collected during the experiments: water content and pore water pressure inside the bank, water levels and velocities at various distances from the bank, dynamic pressures on the bank edge surface and internal pressure fluctuations due to wave impact. Bank geometry profile and bottom topography at different times have also been collected to characterize the erosion rate with time and the evolution of bank retreat. Two types of mass failures were observed during the experiments: slides and toppling failures. The latter were most frequently observed failures, consisting in the toppling of blocks and were often the consequence of the presence of deep tension cracks. In most cases the impact of wind waves caused the

  3. Glacial stratigraphy and ice retreat in Block Island Sound, CT, TI, and NY

    SciTech Connect

    Goss, M.C. . Geological Sciences); Lewis, R.S. )

    1993-03-01

    Re-interpretation of high resolution seismic reflection profiles (732 km of systematic, closely spaced traverses) from Block Island Sound (BIS) has led to the recognition of five distinct seismic facies, of inferred glacial lacustrine origin, above acoustic basement. Facies 1 exhibits chaotic to massive reflection returns, positive relief, and produces a spiked/bouldery return at seafloor outcrops. Facies 1 is inferred till/diamicton deposits and includes previously recognized end moraines. Facies 2, stratigraphically contemporaneous with facies 1 and also a positive relief feature, exhibits chaotic to amorphous returns and grades southward into parallel reflections filling topographic lows. This facies exhibits a shingled sequence from south to north. Facies 2 is inferred to be the proximal and distal portions of sub-aqueous fans. Facies 3, overlying facies 1 and 2, is a laterally extensive thick unit composed of numerous reflections strongly mimicking underlying topography. Facies 3 merges northward into facies 4 which exhibits high amplitude, parallel to sub-parallel reflections dipping gently southward, but unaffected by underlying topography. In the east end of BIS, facies 4 exhibits seaward dipping tangential reflections. Facies 3 and 4 are inferred to be deltaic deposits. The tangential reflections are inferred to be pro-delta slope deposits. Facies 5, associated only with the Narragansett Bay lobe in the far eastern end of BIS, also appears to be a deltaic deposit but grades southward into a massive distal facies. The presence of sequential fans, although few in number, is indicative of an active ice front present during last ice retreat. A linear arrangement of till/diamicton units and the concentration of pro-delta slope deposits approximately two km south of the present shoreline may be a previously unrecognized ice still-stand position.

  4. Rapid loss of phosphorus during early pedogenesis along a glacier retreat choronosequence, Gongga Mountain (SW China)

    PubMed Central

    Zhou, Jun; Bing, Haijian; Sun, Hongyang; Wang, Jipeng

    2015-01-01

    The loss of phosphorus (P) during the early pedogenesis stage is important at the ecosystem level, and it also plays an important role in the global P cycle. The seasonal variation of total P (Pt) and its fractions along a young soil chronosequence (Hailuogou chronosequence) on the eastern slope of Gongga Mountain, SW China, was investigated based on the modified Hedley fractionation technique to understand P loss during the early pedogenesis stage. The results showed that the mineral P (mainly apatite) was the dominant fraction of Pt in the C horizon of the soil, and the seasonal difference in Pt and its fractions was insignificant. In the A horizon, Pt concentrations decreased markedly compared with those in the C horizon, and as the age of the soil increased, the inorganic P (Pi) significantly decreased and the organic P (Po) prominently increased. Seasonally, the P fractions exhibited various distributions in the A horizon. The variation of Pt and its fractions revealed that the P loss was rapid along the 120-year soil chronosequence. The P stocks in soils (0–30 cm) started to decrease at the 52 year site. And the P stock depletion reached almost 17.6% at the 120-year site. The loss of P from the soil of the Hailuogou chronosequence was mainly attributed to weathering, plant uptake, and transport by runoff. About 36% P loss was transported into plant biomass P at the 120 year site. The data obtained indicated that the glacier retreat chronosequence could be used to elucidate the fast rate of P loss during the early pedogenic stage. PMID:26557441

  5. Soil greenhouse gas fluxes during wetland forest retreat along the lower Savannah River, Georgia (USA)

    USGS Publications Warehouse

    Krauss, Ken W.; Whitbeck, Julie L.

    2012-01-01

    Tidal freshwater forested wetlands (tidal swamps) are periodically affected by salinity intrusion at seaward transitions with marsh, which, along with altered hydrology, may affect the balance of gaseous carbon (C) and nitrogen (N) losses from soils. We measured greenhouse gas emissions (CO2, CH4, N2O) from healthy, moderately degraded, and degraded tidal swamp soils undergoing sea-level-rise-induced retreat along the lower Savannah River, Georgia, USA. Soil CO2 flux ranged from 90.2 to 179.1 mg CO2 m-2 h-1 among study sites, and was the dominant greenhouse gas emitted. CO2 flux differed among sites in some months, while CH4 and N2O fluxes were 0.18 mg CH4 m-2 h-1 and 1.23 μg N2O m-2 h-1, respectively, with no differences among sites. Hydrology, soil temperature, and air temperature, but not salinity, controlled the annual balance of soil CO2 emissions from tidal swamp soils. No clear drivers were found for CH4 or N2O emissions. On occasion, large ebbing or very low tides were even found to draw CO2 fluxes into the soil (dark CO2 uptake), along with CH4 and N2O. Overall, we hypothesized a much greater role for salinity and site condition in controlling the suite of greenhouse gases emitted from tidal swamps than we discovered, and found that CO2 emissions-not CH4 or N2O-contributed most to the global warming potential from these tidal swamp soils.

  6. Soil greenhouse gas fluxes during wetland forest retreat along the Lower Savannah River, Georgia (USA)

    USGS Publications Warehouse

    Krauss, Ken W.; Whitbeck, Julie L.

    2012-01-01

    Tidal freshwater forested wetlands (tidal swamps) are periodically affected by salinity intrusion at seaward transitions with marsh, which, along with altered hydrology, may affect the balance of gaseous carbon (C) and nitrogen (N) losses from soils. We measured greenhouse gas emissions (CO2, CH4, N2O) from healthy, moderately degraded, and degraded tidal swamp soils undergoing sea-level-rise-induced retreat along the lower Savannah River, Georgia, USA. Soil CO2 flux ranged from 90.2 to 179.1 mg CO2 m-2 h-1 among study sites, and was the dominant greenhouse gas emitted. CO2 flux differed among sites in some months, while CH4 and N2O fluxes were 0.18 mg CH4 m-2 h-1 and 1.23 μg N2O m-2 h-1, respectively, with no differences among sites. Hydrology, soil temperature, and air temperature, but not salinity, controlled the annual balance of soil CO2 emissions from tidal swamp soils. No clear drivers were found for CH4 or N2O emissions. On occasion, large ebbing or very low tides were even found to draw CO2 fluxes into the soil (dark CO2 uptake), along with CH4 and N2O. Overall, we hypothesized a much greater role for salinity and site condition in controlling the suite of greenhouse gases emitted from tidal swamps than we discovered, and found that CO2 emissions–not CH4 or N2O–contributed most to the global warming potential from these tidal swamp soils.

  7. Retreat of the Coalescent Greenland and Innuitian Ice Sheets from Nares Strait

    NASA Astrophysics Data System (ADS)

    Jennings, A. E.; Bailey, E.; Oliver, B.; Andrews, J. T.; Prins, M. A.; Troelstra, S.; Stoner, J. S.; Reilly, B. T.; Davies-Walczak, M.; Mix, A. C.

    2015-12-01

    Nares Strait, which forms one of the main connections between the Arctic Ocean and Baffin Bay was blocked by coalescent Innuitian and Greenland ice sheets during the LGM. Nares Strait opened ca. 9000 cal ka BP when the connection between the two ice sheets was finally severed. Our research focuses on the events and processes leading up to the opening of the strait and the response of the glacier and marine systems to establishment of the throughflow. The study at present involves new analysis of two sediment cores: 2001LSSL-163PC from Smith Sound, at the southern end of Nares Strait, and 2001LSSL-079PC from the mouth of Petermann Fjord at the northern end of the strait. X-radiography and core photographs were studied to establish basic lithofacies and stratigraphy. Foraminiferal faunas provide insight into changes in ice margin proximity, Atlantic Water advection and sea-ice conditions and are used to develop the radiocarbon chronologies. Quantitative X-ray diffraction analysis of bulk sediments aids in determining sediment provenance and the establishment of a north to south connection. Grain size analysis allows sediment processes and sedimentary environments, such as iceberg rafting, current deposition, and sub ice-shelf deposition to be evaluated. A radiocarbon date of >50 kyr was obtained from foraminifera in an overconsolidated, gray diamicton in core 163PC. The diamicton is overlain by a red deglacial sequence of barren laminated sediments followed by gray pebbly mud. Two radiocarbon dates submitted from near the base of the pebbly mud constrain the timing of ice retreat from Smith Sound. The chronology of core 079PC indicates that it captures the opening of Nares Strait, but 4 submitted radiocarbon dates will further constrain its chronology. The goal of the work on these two cores is to lay a framework for extensive marine fieldwork to study ice sheet-ocean interactions in the Petermann Glacier in late summer 2015.

  8. Coastal retreat and improved water quality mitigate losses of seagrass from sea level rise.

    PubMed

    Saunders, Megan I; Leon, Javier; Phinn, Stuart R; Callaghan, David P; O'Brien, Katherine R; Roelfsema, Chris M; Lovelock, Catherine E; Lyons, Mitchell B; Mumby, Peter J

    2013-08-01

    The distribution and abundance of seagrass ecosystems could change significantly over the coming century due to sea level rise (SLR). Coastal managers require mechanistic understanding of the processes affecting seagrass response to SLR to maximize their conservation and associated provision of ecosystem services. In Moreton Bay, Queensland, Australia, vast seagrass meadows supporting populations of sea turtles and dugongs are juxtaposed with the multiple stressors associated with a large and rapidly expanding human population. Here, the interactive effects of predicted SLR, changes in water clarity, and land use on future distributions of seagrass in Moreton Bay were quantified. A habitat distribution model of present day seagrass in relation to benthic irradiance and wave height was developed which correctly classified habitats in 83% of cases. Spatial predictions of seagrass and presence derived from the model and bathymetric data were used to initiate a SLR inundation model. Bathymetry was iteratively modified based on SLR and sedimentary accretion in seagrass to simulate potential seagrass habitat at 10 year time steps until 2100. The area of seagrass habitat was predicted to decline by 17% by 2100 under a scenario of SLR of 1.1 m. A scenario including the removal of impervious surfaces, such as roads and houses, from newly inundated regions, demonstrated that managed retreat of the shoreline could potentially reduce the overall decline in seagrass habitat to just 5%. The predicted reduction in area of seagrass habitat could be offset by an improvement in water clarity of 30%. Greater improvements in water clarity would be necessary for larger magnitudes of SLR. Management to improve water quality will provide present and future benefits to seagrasses under climate change and should be a priority for managers seeking to compensate for the effects of global change on these valuable habitats.

  9. Glacitectonic deformation around the retreating margin of the last Irish ice sheet

    NASA Astrophysics Data System (ADS)

    Knight, J.

    2008-12-01

    Evidence for ice-marginal glacitectonic shunting and deformation of bedrock slabs is described from three sites around the west coast of Ireland. These sites (Brandon Bay, County Kerry; Pigeon Point, County Mayo; Inishcrone, County Sligo) are all locations where the late Devensian ice margin retreated on land and was confined to within limestone bedrock embayments. At these sites, flat-lying bedrock slabs (< 8 m long) have been dissociated from rockhead and moved seaward (in the direction of ice flow) by glacitectonic shunting. At all of the sites, bedrock slabs have been variously stacked, rotated, deformed into open folds, and brecciated. Separating the bedrock slabs is either a thin layer (< 20 cm) of brecciated and mylonitised cemented bedrock that shows internal folding; or a thicker (< 50 cm) normally-graded diamicton with a fine matrix. Together, the presence of these features suggests oscillation of a polythermal and clean basal ice margin that was strongly associated with basal freeze-on and the presence of proglacial permafrost. Subglacial sediment-laden meltwater was focused from behind the ice margin and through permafrost taliks. It is suggested that hydrofracturing under high hydraulic pressure, and through a frozen-bed ice margin, forced sediment injection into bedrock fractures and bedding planes and away from the ice margin, and that bedrock slabs were moved in part by hydraulic lift as well as thrust-style ice-marginal tectonics. The presence of a mosaic of warm and frozen ice-bed patches, in combination with strong geologic control and meltwater generation from behind the ice margin, can help explain formation of these unusual bedrock slab features.

  10. Differences in ice retreat across Pine Island Bay, West Antarctica, since the Last Glacial Maximum: Indications from multichannel seismic reflection data

    USGS Publications Warehouse

    Uenzelmann-Neben, G.; Gohl, K.; Larter, R.D.; Schlüter, P.

    2007-01-01

    An understanding of the glacial history of Pine Island Bay (PIB) is essential for refining models of the future stability of the West Antarctic Ice Sheet (WAIS). New multichannel seismic reflection data from inner PIB are interpreted in context of previously published reconstructions for the retreat history in this area since the Last Glacial Maximum. Differences in the behavior of the ice sheet during deglaciation are shown to exist for the western and eastern parts of PIB. While we can identify only a thin veneer of sedimentary deposits in western PIB, eastern PIB shows sedimentary layers ≤ 400 msTWT. This is interpreted as a result of differences in ice retreat: a fast ice retreat in western PIB accompanied by rapid basal melting led to production of large meltwater streams, a slower ice retreat in eastern PIB is most probably the result of smaller drainage basins resulting in less meltwater production.

  11. Influence of Threshold for Bedrock Erosion on River Long Profile Development and Knickzone Retreat in Response to Tectonic Perturbation

    NASA Astrophysics Data System (ADS)

    Attal, M.; Hobley, D.; Cowie, P. A.; Whittaker, A. C.; Tucker, G. E.; Roberts, G. P.

    2008-12-01

    Prominent convexities in channel long profiles, or knickzones, are an expected feature of bedrock rivers responding to a change in the rate of base level fall driven by tectonic processes. In response to a change in relative uplift rate, the simple stream power model which is characterized by a slope exponent equal to unity predicts that knickzone retreat velocity is independent of uplift rate and that channel slope and uplift rate are linearly related along the reaches which have re-equilibrated with respect to the new uplift condition (i.e., downstream of the profile convexity). However, a threshold for erosion has been shown to introduce non- linearity between slope and uplift rate when associated with stochastic rainfall variability. We present field data regarding the height and retreat rates of knickzones in rivers upstream of active normal faults in the central Apennines, Italy, where excellent constraints exist on the temporal and spatial history of fault movement. The knickzones developed in response to an independently-constrained increase in fault throw rate 0.75 Ma. Channel characteristics and Shield stress values suggest that these rivers lie close to the detachment-limited end-member but the knickzone retreat velocity (calculated from the time since fault acceleration) has been found to scale systematically with the known fault throw rates, even after accounting for differences in drainage area. In addition, the relationship between measured channel slope and relative uplift rate is non-linear, suggesting that a threshold for erosion might be effective in this setting. We use the Channel-Hillslope Integrated Landscape Development (CHILD) model to quantify the effect of such a threshold on river long profile development and knickzone retreat in response to tectonic perturbation. In particular, we investigate the evolutions of 3 Italian catchments of different size characterized by contrasted degree of tectonic perturbation, using physically realistic

  12. Exploring the cliff retreat response to base level change using SFM photogrammetry and cosmogenic 36Cl, Coal Cliffs, Utah, USA

    NASA Astrophysics Data System (ADS)

    Sheehan, C.; Ward, D.

    2015-12-01

    The retreat of cliffbands is an important erosional process within the relatively undeformed sedimentary layers of the Colorado Plateau. Many iconic cliff landforms, including those of Monument Valley and Grand Canyon, are maintained by the interaction of these different rock types. A several kilometer thickness of incised sandstone and shale formations allow this region to act as a natural laboratory for studying the effects of variable lithologies on landscape evolution. Cliffband morphology and retreat on the plateau are controlled by several factors that may vary over time and space, including lithology, rate and distribution of rockfall debris, bedrock structure, baselevel, and climate. The relative importance of each factor in setting rates of cliff retreat are not entirely clear. Because regional headwaters are commonly sourced at cliff bases, these landforms are often the final and slowest areas to respond to baselevel changes, allowing rockfall and other local stochastic processes to overwhelm the erosional response to a baselevel forcing. The roles of these processes are difficult to assess because very few measurements of retreat rates over geomorphic timescales (103-106 years) have been produced, and thus changes in cliffband position through time have only been constrained by inferences made from the regional erosional history. Here, we control for climate and rock type by focusing on a continuous, 40-kilometer section of the lithologically consistent Coal Cliffs in Emery County, Utah. This area presents several natural experiments illustrating cliffband response to different forcings, including relict surfaces reflecting a baselevel change, drainage divides across which the adjustment to base level change may be asynchronous, a zone wherein the caprock layer has been removed by backscarp erosion, and a generally continuous gradient in cliff height from 50 to >200 meters along the cliffline. We employ terrestrial Cl36 exposure dating on terraces, talus

  13. Amundsen-coast grounding-line retreat mapped with satellite photogrammetry and Ice Bridge and ICESat laser altimetry

    NASA Astrophysics Data System (ADS)

    Smith, B. E.; Shean, D. E.; Joughin, I. R.

    2012-12-01

    The Amundsen coast of Antarctica is at present the site of some of the largest ice-sheet contributions to global sea-level change. NASA's Ice Bridge program has made detailed ice-thickness and altimetry surveys on the principal glaciers in this region, including Pine Island, Thwaites, Pope and Smith, focusing attention on the grounding zones in each case, where warming ocean waters have led to thinning of the seaward ends of these glaciers. This has led to accelerated discharge in three ways: by directly removing ice from the glaciers, by steepening the surface profiles near the grounding zone, and by thinning the ice towards the flotation point, reducing the area in contact with the bed and removing basal shear stress. By combining data from IceSat and Ice Bridge laser altimetry with Worldview stereophotogrammetry, we have developed maps of elevation change throughout the basins of these glaciers. These, together with Ice Bridge and AGASEA ice-thickness measurements, allow us to estimate ice freeboard at any time between 2003 and 2011 for any point for which we have an ice thickness measurement. Based on this, we have mapped grounding line positions for the major surveyed glaciers in the area. These maps show extensive grounding-line retreat in Pine Island and Pope glaciers through 2010, and substantial thinning near the Thwaites ice shelf bringing further ice into flotation. Extrapolation of current thinning rates, under the assumption that their spatial pattern and magnitude will remain constant, gives one scenario for the near future rate of grounding line retreat. Under this scenario, the current rate grounding line retreat can continue, at least locally, for the next 20-30 years, with slower rates of retreat thereafter as the grounding line reaches ice with larger surface slopes. Alternately, if the thinning pattern follows the grounding line, with peak thinning rates in the 10-20 km immediately upstream of the grounding line, the initial phase of the retreat

  14. Controls on erosional retreat of the uplifted rift flanks at the Gulf of Suez and northern Red Sea

    NASA Technical Reports Server (NTRS)

    Steckler, Michael S.; Omar, Gomaa I.

    1994-01-01

    The Gulf of Suez and the Red Sea rigts are currently bordered by large asymmetric uplifts that are undergoing erosion. We find that the amount and timing of erosion vary systematically along the strike of the margin and have been controlled by variations in the perift stratigraphy. The perfit strata are compsoed of cliff-forming Eocene-Cretaceous carbonates overlaying the easily eroded Cretaceous-Cambrian 'Nubian' sandstone. This lithologic succession promotes scarp retreat of the sedimentary section, follwed by dissection of the underlying basement. The perift section thins from over 2000 m at the northern end of the rift to less htan 400 m at its junction with the Red Sea. Thus, at the northern part of the Gulf of Suez, the Nubian sandstone is minimally exposed, and the carbonates form a scarp at the rift border fault. Farther south, undercuttin of hte carbonates by erosion of the sandstion has resulted in scarp retreat. The escarpment cuts diagonally away from the border fault andis over 100 km inland from the border fault at the southernmost Gulf of Suez. The amount of retreat varies inversely with the sediment thickness. Exposure and erosion of basement are initiated by the retreate of the escarpment, and the depth of erosion, as indicated by fission track ages, increases with distance from the escarpment. These observations are explained by a model in which erosion along the Gulf of Suez is initiated as rift flank uplift becomes sufficiently large ot expose the friable sandstones. Undercutting the escarpment and exhumation of basement has been propagating northward and westward for at least 20 m.y. The average rate of scarp retreat has been 6 km/m.y. and the along-strike propagation of the erosion has been 12 km/m.y. The diachronous erosion of the rift flanks at the Gulf of Suez highlights the importance of distinguishing between the timing of uplift and of erosion. Both thermochronometric and stratigraphic data primarily indicate the timing of erosion, which

  15. Sedimentology and chronology of the advance and retreat of the last British-Irish Ice Sheet on the continental shelf west of Ireland

    NASA Astrophysics Data System (ADS)

    Peters, Jared L.; Benetti, Sara; Dunlop, Paul; Ó Cofaigh, Colm; Moreton, Steven G.; Wheeler, Andrew J.; Clark, Christopher D.

    2016-05-01

    The last British-Irish Ice Sheet (BIIS) had extensive marine-terminating margins and was drained by multiple large ice streams and is thus a useful analogue for marine-based areas of modern ice sheets. However, despite recent advances from investigating the offshore record of the BIIS, the dynamic history of its marine margins, which would have been sensitive to external forcing(s), remain inadequately understood. This study is the first reconstruction of the retreat dynamics and chronology of the western, marine-terminating, margin of the last (Late Midlandian) BIIS. Analyses of shelf geomorphology and core sedimentology and chronology enable a reconstruction of the Late Midlandian history of the BIIS west of Ireland, from initial advance to final retreat onshore. Five AMS radiocarbon dates from marine cores constrain the timing of retreat and associated readvances during deglaciation. The BIIS advanced without streaming or surging, depositing a bed of highly consolidated subglacial traction till, and reached to within ˜20 km of the shelf break by ˜24,000 Cal BP. Ice margin retreat was likely preceded by thinning, grounding zone retreat and ice shelf formation on the outer shelf by ˜22,000 Cal BP. This ice shelf persisted for ≤2500 years, while retreating at a minimum rate of ˜24 m/yr and buttressing a >150-km long, 20-km wide, bathymetrically-controlled grounding zone. A large (˜150 km long), arcuate, flat-topped grounding-zone wedge, termed here the Galway Lobe Grounding-Zone Wedge (GLGZW), was deposited below this ice shelf and records a significant stillstand in BIIS retreat. Geomorphic relationships indicate that the BIIS experienced continued thinning during its retreat across the shelf, which led to increased topographic influence on its flow dynamics following ice shelf break up and grounding zone retreat past the GLGZW. At this stage of retreat the western BIIS was comprised of several discrete, asynchronous lobes that underwent several readvances

  16. Van Kampen modes for bunch longitudinal motion

    SciTech Connect

    Burov, A.; /Fermilab

    2010-09-01

    Conditions for existence, uniqueness and stability of bunch steady states are considered. For the existence uniqueness problem, simple algebraic equations are derived, showing the result both for the action and Hamiltonian domain distributions. For the stability problem, van Kampen theory is used. Emerging of discrete van Kampen modes show either loss of Landau damping, or instability. This method can be applied for an arbitrary impedance, RF shape and beam distribution function Available areas on intensity-emittance plane are shown for resistive wall wake and single harmonic, bunch shortening and bunch lengthening RF configurations. Language of van Kampen modes is a powerful tool for studying beam stability. Its unique efficiency reveals itself in those complicated cases, when the dielectric function cannot be obtained, as it is for the longitudinal bunch motion. Emergence of a discrete mode means either loss of Landau damping or instability. By definition, the discrete modes lie outside the continuous incoherent spectrum, but they still may stay within the bucket. In the last case, the discrete mode would disappear after a tiny portion of resonant particles would be added. However, if the discrete mode lie outside the bucket, the Landau damping cannot be restored by tiny perturbation of the particle distribution; LLD is called radical in that case. For a given bunch emittance and RF voltage, the intensity is limited either by reduction of the bucket acceptance or by (radical) LLD. In this paper, results are presented for longitudinal bunch stability in weak head-tail approximation and resistive wall impedance; three RF configurations are studied: single harmonic, bunch shortening and bunch lengthening. It is shown that every RF configuration may be preferable, depending on the bunch emittance and intensity.

  17. Slab roll-back and trench retreat as controlling factor for basin subsidence in southern Central America

    NASA Astrophysics Data System (ADS)

    Brandes, Christian; Winsemann, Jutta

    2015-04-01

    Slab roll-back and trench retreat are important factors for basin subsidence, magma generation and volcanism in arc-trench systems. Based on the sedimentary and tectonic record of the southern Central American island-arc we conclude that repeated phases of slab roll-back and trench retreats occurred the arc-trench system since the Late Cretaceous. These trench retreats were most probably related to the subduction of oceanic plateaus and seamounts and effected both the fore-arc and back-arc evolution. We used numerical basin modelling techniques to analyse the burial history of fore-arc and back-arc basins in Central America and combined the results with field data of the sedimentological evolution of the basin-fills. From the basin models, geohistory curves were extracted for the fore-arc and back-arc basins to derive the subsidence evolution. The Sandino Fore-arc Basin is characterized by low subsidence during the first 40 Myr. Since the Late Cretaceous the basin has a linear moderate subsidence with a phase of accelerated subsidence in the Oligocene. In the North and South Limón Back-arc Basin, subsidence started at approximately the same time as in the Sandino Fore-arc Basin. The North and South Limón Basins show a linear subsidence trend in the Paleocene and Eocene. Evidence for trench retreats is given by pulses of uplift in the outer-arc area, followed by subsidence in both the fore-arc and back-arc basins. The first slab roll-back probably occurred during the Early Paleocene. This is indicated by the collapse of carbonate platforms, and the re-deposition of large carbonate blocks into deep-water turbidites. A new pulse of uplift or decreased subsidence, respectively during the Late Eocene is attributed to subduction of rough crust. A subsequent slab detachment and the establishment of a new subduction zone further westward was described by Walther et al. (2000). Strong uplift affected the entire fore-arc area, which led to the deposition of very coarse

  18. Drift compression of an intense neutralized ion beam

    SciTech Connect

    Roy, P.K.; Yu, S.S.; Henestroza, E.; Anders, A.; Bieniosek, F.M.; Coleman, J.; Eylon, S.; Greenway, W.G.; Leitner, M.; Logan, B.G.; Waldron, W.L.; Welch, D.R.; Thoma, C.; Sefkow, A.B.; Gilson, E.P.; Efthimion, P.C.; Davidson, R.C.

    2004-10-25

    Longitudinal compression of a tailored-velocity, intense neutralized ion beam has been demonstrated. The compression takes place in a 1-2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhancing the beam peak current by a factor of 50 and producing a pulse duration of about 3 ns. this measurement has been confirmed independently with two different diagnostic systems.

  19. Longitudinal distribution of cosmic rays in the heliosphere

    NASA Technical Reports Server (NTRS)

    Gold, R. E.; Venkatesan, D.

    1985-01-01

    The longitudinal distribution of cosmic ray intensity was examined during the years 1974-1976 when the persistent high speed solar wind stream structures produced a well ordered inner heliosphere. Solar wind velocity is mapped back to the Sun and compared with cosmic ray intensity which is represented relative to the solar rotation average. Low solar wind velocity is observed to be a necessary, but not sufficient, condition for the occurrence of higher cosmic ray intensities at 1 AU. These relative enhancements cover a restricted range of heliographic longitudes and persist for several solar rotations. The observed solar wind and cosmic ray intensity relationships are consistent with a simple model suggested here in which cosmic ray modulation is very weak in the inner heliosphere, sunward of the first shock crossing on each field line and more intense in the outer heliosphere.

  20. Fast developed Da-An Gorge: Rapid fluvial incision and knickpoint retreat across a co-seismic popup zone of the 1999 Chi-Chi earthquake, Taiwan

    NASA Astrophysics Data System (ADS)

    Lee, Jian-Cheng; Chen, Ming-Chu; Frankel, Kurt; Chan, Yu-Chang; Hsieh, Meng-Long; Tseng, Chia-Han

    2014-05-01

    A 1-km-long segment in the lower Da-An River in fold-thrust belt of western Taiwan was uplifted ~10 m during the 1999 Mw 7.6 Chi-Chi earthquake, that was subsequently resulting in a 20- to 30-m-deep bedrock gorge within less than 10 years. The amount of coseismic uplift along the channel bed does not fully explain the resulting bedrock channel incision. Using a series of aerial photographs, high-resolution digital elevation models (DEM), and real-time kinematic global positioning system (RTK GPS) surveys, we characterized knickpoint retreat and fluvial incision in the Da-An River gorge. We also analyzed discharge and precipitation data and collected measurements of rock strength and joint plane orientations to better understand the climatic, lithological, and structural influence on the evolution of the actively incising gorge. Two stages of fluvial incision and knickpoint migration are identified in the gorge following the surface uplift during the Chi-Chi earthquake. From 1999 to 2004, 3 to 5 m of alluvium was removed from the channel bed, followed by 3 to 4 m of bedrock channel incision. The knickpoint generated immediately after the earthquake remained where the uplift occurred in 1999. Since 2005, the channel bed has lowered rapidly with local incision rates as high as 15 m/yr. The average upstream knickpoint migration rate over the period 2005 to 2009 was 238 m/yr; total upstream migration from the location of knickpoint formation was about 1190 m. While tectonic uplift formed the knickpoint and set the stage for channel incision, climate played a critical role in accelerating the fluvial response to coseismic displacement. More than 20 m of vertical bedrock channel incision and 1180 m of upstream knickpoint migration occurred primarily during the post-2005 typhoon seasons (May-October). Based on repeat surveys of the Da-An River longitudinal profile and analysis of precipitation and discharge data, we suggest that a discharge threshold of 1200 to 2600 m

  1. Longitudinal and transverse magnetic field program procedure and detailed specification for Sigma 5

    NASA Technical Reports Server (NTRS)

    Wang, C. K.

    1980-01-01

    A computer program and procedure for plotting the contour of the data transferred from the Marshall Space Flight Center solar magnetography is presented. The plotted data then can be easily compared with solar data from other sources, such as the Solar Maximum Mission. From the data file for circular polarization the longitudinal program plots the contours for filtered longitudinal plot and intensity plot by choosing the positive and negative contour levels, intensity levels, and also X,Y plotting ranges which need to be used. In a similar manner the transverse program generates the transverse contour plot, azimuth plot, and intensity plot from the linear polarization data files.

  2. The influence of shear bands on the grounding line retreat in Pine Island Glacier

    NASA Astrophysics Data System (ADS)

    Favier, Lionel; Durand, Gaël; Cornford, Stephen; Gagliardini, Olivier; Zwinger, Thomas

    2013-04-01

    Pine Island Glacier (PIG), West Antarctica, is known as the weak underbelly of the West Antarctic Ice Sheet. During the last 30 years, it has undergone a dramatic acceleration along with a retreat of its grounding line. The main ice stream draining PIG is laterally bounded by two thin bands of damaged ice. These shear bands may play a key role in the dynamics of the grounding line since they likely decrease the ice-shelf buttressing. The traditional approach is generally to infer the viscosity from surface velocity using data assimilation methods. However, in that case the inverse problem is under-constrained when it is coupled to the inversion of basal drag: different set of basal drag and viscosity pattern solution can lead to a good match between modelled and observed surface velocities, but would lead to different prognostic solutions associated to different grounding line migrations. Here, we follow a simpler approach and perform a sensitivity study on the shear bands effective viscosity, and its consequences for the ice dynamics. The areas of fractured ice at PIG are located using a recent SPOT satellite image. The non-fractured ice viscosity depends on ice temperatures while the fractured ice viscosity is decreased through a sensitivity study to reproduce the damaged ice of the shear bands. Using two different higher-order models (Elmer/Ice and BISICLES), we investigate the influence of the shear bands' damage on the grounding line dynamics. Each experiment in the sensitivity study gathers successively (i) the determination of basal drag through assimilation methods, (ii) a geometry relaxation over 15 years and (iii) transient perturbation experiments driven by different calving sizes. The initial geometry of the ice sheet arises from the ALBMAP data set on a 1 km grid resolution, velocities were acquired during the last International polar Year, and non-fractured ice viscosities are deduced from prescribed temperatures computed with a higher order model. We

  3. Historic bluff retreat and stabilization at Flag Harbor, Chesapeake Bay, Maryland

    USGS Publications Warehouse

    Clark, Inga; Larsen, Curtis E.; McRae, Michele

    2002-01-01

    the toes of slopes from wave action. Once shoreline retreat ends, sloughing of sediment from bluff faces gives way to longer-term landslide processes. The bluff top recedes until a stable 35-degree slope is attained. Thus, simple shoreline protection methods may not preserve property at the bluff edge.

  4. Engineering parabolic beams with dynamic intensity profiles.

    PubMed

    Ruelas, Adrian; Lopez-Aguayo, Servando; Gutiérrez-Vega, Julio C

    2013-08-01

    We present optical fields formed by superposing nondiffracting parabolic beams with distinct longitudinal wave-vector components, generating light profiles that display intensity fluxes following parabolic paths in the transverse plane. Their propagation dynamics vary depending on the physical mechanism originating interference, where the possibilities include constructive and destructive interference between traveling parabolic beams, interference between stationary parabolic modes, and combinations of these. The dark parabolic region exhibited by parabolic beams permits a straightforward superposition of intensity fluxes, allowing formation of a variety of profiles, which can exhibit circular, elliptic, and other symmetries.

  5. A comparative evaluation of two rotary Ni-Ti instruments in the removal of gutta-percha during retreatment

    PubMed Central

    Preetam, C. S.; Chandrashekhar, M.; Gunaranjan, T.; Kumar, S. Kishore; Miskeen Sahib, S. A.; Kumar, M. Senthil

    2016-01-01

    Aim: The purpose of this study is to achieve an effective method to remove root canal filling material from the root canal system. The study, thus, aims to evaluate the efficacy of the cleaning ability of two different rotary Ni-Ti systems; ProTaper Retreatment files and RaCe System compared to hand instrumentation with Hedstrom files for the removal of gutta-percha during retreatment. Materials and Methods: Thirty mandibular premolars with one single straight canal were decoronated and instrumented with ProTaper files and filled with thermoplastic gutta-percha. After 30 days, the samples were divided into three groups and gutta-percha was removed with the test instruments. The postoperative radiographs were evaluated with known criteria by dividing the root into cervical third, middle third, and apical third. The results were tabulated and Statistical Package for Social Sciences Software (IBM Corporation) was used for analysis. Results: The mean deviation of the results were first calculated and then t-test and analysis of variance test (two-tailed P value) were evaluated for establishing significant differences. The rotary instruments were effective in removing the gutta-percha from the canals. Therefore, significant difference was observed between the efficacies of the two rotary systems used. The rotary instruments showed effective gutta-percha removal in the cervical and middle one third. (P > 0.05). However, apical debridement was effective with Hedstrom files. Conclusion: The study concluded the use of both rotary and hand instrumentation for effective removal of gutta-percha for retreatment. PMID:27652245

  6. A comparative evaluation of two rotary Ni-Ti instruments in the removal of gutta-percha during retreatment

    PubMed Central

    Preetam, C. S.; Chandrashekhar, M.; Gunaranjan, T.; Kumar, S. Kishore; Miskeen Sahib, S. A.; Kumar, M. Senthil

    2016-01-01

    Aim: The purpose of this study is to achieve an effective method to remove root canal filling material from the root canal system. The study, thus, aims to evaluate the efficacy of the cleaning ability of two different rotary Ni-Ti systems; ProTaper Retreatment files and RaCe System compared to hand instrumentation with Hedstrom files for the removal of gutta-percha during retreatment. Materials and Methods: Thirty mandibular premolars with one single straight canal were decoronated and instrumented with ProTaper files and filled with thermoplastic gutta-percha. After 30 days, the samples were divided into three groups and gutta-percha was removed with the test instruments. The postoperative radiographs were evaluated with known criteria by dividing the root into cervical third, middle third, and apical third. The results were tabulated and Statistical Package for Social Sciences Software (IBM Corporation) was used for analysis. Results: The mean deviation of the results were first calculated and then t-test and analysis of variance test (two-tailed P value) were evaluated for establishing significant differences. The rotary instruments were effective in removing the gutta-percha from the canals. Therefore, significant difference was observed between the efficacies of the two rotary systems used. The rotary instruments showed effective gutta-percha removal in the cervical and middle one third. (P > 0.05). However, apical debridement was effective with Hedstrom files. Conclusion: The study concluded the use of both rotary and hand instrumentation for effective removal of gutta-percha for retreatment.

  7. Association of an auroral surge with plasma sheet recovery and the retreat of the substorm neutral line

    SciTech Connect

    Hones, E.W. ); Elphinstone, R.; Murphree, J.S. . Dept. of Physics); Galvin, A.B. . Dept. of Space Physics); Heinemann, N.C. . Dept. of Physics); Parks, G.K. ); Rich, F.J. (Air Force Geophysics Lab., Hanscom AFB, MA

    1990-01-01

    One of the periods being studied in the PROMIS CDAW (CDAW-9) workshops is the interval 0000-1200 UT on May 3, 1986, designated Event 9C.'' A well-defined substorm, starting at 0919 UT, was imaged by both DE 1 over the southern hemisphere and Viking over the northern hemisphere. The images from Viking, at 80-second time resolution, showed a surge-like feature forming at about 0952 UT at the poleward edge of the late evening sector of the oval. The feature remained relatively stationary until about 1000 UT when it seemed to start advancing westward. ISEE 1 and 2 were closely conjugate to the surge as mapped from both the DMSP and Viking images. We conclude that the plasma sheet recovery was occasioned by the arrival at ISEE 1,2 of a westward traveling wave of plasma sheet thickening, the wave itself being formed by westward progression of the substorm neutral line's tailward retreat. The westward traveling surge was the auroral manifestation of this nonuniform retreat of the neutral line. We suggest that the upward field aligned current measured by DMSP F7 above the surge head was driven by plasma velocity shear in the plasma sheet at the duskward kink'' in the retreating neutral line. By analogy with this observation we propose that the westward traveling surges and the current wedge field aligned currents that characterize the expanding auroral bulge during substorm expansive phase are manifestations of (and are driven by) velocity shear in the plasma sheet near the ends of the extending substorm neutral line.

  8. CO(2) and N(2)O emissions in a soil chronosequence at a glacier retreat zone in Maritime Antarctica.

    PubMed

    Thomazini, A; Mendonça, E S; Teixeira, D B; Almeida, I C C; La Scala, N; Canellas, L P; Spokas, K A; Milori, D M B P; Turbay, C V G; Fernandes, R B A; Schaefer, C E G R

    2015-07-15

    Studies of C cycle alterations are extremely important to identify changes due to climate change, especially in the polar ecosystem. The objectives of this study were to (i) examine patterns of soil CO2-C and N2O-N emissions, and (ii) evaluate the quantity and quality of soil organic matter across a glacier retreat chronosequence in the Maritime Antarctica. Field measurements were carried out during January and February 2010 (summer season) along a retreating zone of the White Eagle Glacier, at King George Island, Maritime Antarctica. Soil samples (0-10cm) were collected along a 500-m transect at regular intervals to determine changes in soil organic matter. Field CO2-C emission measurements and soil temperature were carried out at regular intervals. In addition, greenhouse gas production potentials were assessed through 100days laboratory incubations. Soils exposed for a longer time tended to have greater concentrations of soluble salts and possess sandier textures. Total organic C (3.59gkg(-1)), total N (2.31gkg(-1)) and labile C (1.83gkg(-1)) tended to be lower near the glacier front compared with sites away from it, which is correlated with decreasing degree of humification of the soil organic matter with exposure time. Soil CO2-C emissions tended to increase with distance from the glacier front. On average, the presence of vegetation increased CO2-C emissions by 440%, or the equivalent of 0.633g of CO2-C m(-2)h(-1). Results suggest that newly exposed landsurfaces undergo soil formation with increasing labile C input from vegetation, accompanied by increasing soil CO2-C emissions. Despite the importance of exposure time on CO2-C production and emissions, there was no similar trend in soil N2O-N production potentials as a function of glacial retreat. For N2O, instead, the maximum production occurred in sites with the first stages of vegetation growth. PMID:25855094

  9. Examination of upstream flow dynamics in response to the front retreat of ice shelves with different geometric configurations

    NASA Astrophysics Data System (ADS)

    Wang, S.; Liu, H.

    2015-12-01

    Ice shelves fringe ~75% of Antarctica's coastline, nourished by numerous terrestrial glacier systems. The ice-shelf disintegrations in recent decades and the observed thinning trends have revealed their susceptibility to the atmospheric and oceanic changes in the climate warming context. The buttressing effect of an ice shelf constrains the ice discharge of its upstream land ice, thus regulating the contribution to sea level of the terrestrial glaciers. The important role of ice shelves in stabilizing the upstream glacier flow dynamics is emphasized by the rapid accelerations and thinning of the tributary glaciers in response to the collapses of the northern Larsen Ice Shelf in Antarctic Peninsula. However, this buttressing effect is determined by the stress balance conditions of an ice shelf, which is further affected by the ice-shelf geometric configurations. The ice shelves confined by fjords, islands, promontories or seabed topographic highs exert greater buttressing effects than those less confined by the lateral or basal shear stresses. This research aims to assess the influences of different ice-shelf configurations on upstream flow dynamics in response to large ice-shelf retreat events. By using remotely sensed imagery acquired by multiple satellite missions, we derived the time series surface velocity records for the Larsen B glacier-ice shelf system in Antarctic Peninsula during 1995 - 2015 and for the Mertz glacier-ice shelf system in East Antarctica during 1997 - 2015, respectively. The former was well confined in the embayment, while the latter is unconfined by lateral margins. We compared the different temporal variation patterns in flow dynamics between these two sites before and after their large retreating events, i.e. the collapse event of Larsen B Ice Shelf in 2002 and the large calving event of Mertz Ice Shelf in 2010. The surface velocity profiles reveal the less sensitivity of upstream responses to the front retreat for the Mertz Ice Shelf.

  10. Restoration and recovery of hurricane-damaged mangroves using the knickpoint retreat effect and tides as dredging tools.

    PubMed

    Bashan, Yoav; Moreno, Manuel; Salazar, Bernardo G; Alvarez, Leonardo

    2013-02-15

    In 2001, a hurricane moved a large sand dune, blocking the sole outlet channel of a mangrove. In the absence of daily tidal flow, the two ponds containing the mangrove vegetation evaporated, the secondary drainage channels were lost, and a salt crust formed on the bed of the ponds. The mangrove lost most of its trees and the remaining suffered from osmotic shock that led to defoliation. Restoration involved creating a knickpoint retreat (waterfall retreat effect) and tidal flow as a dredging mechanism to restore the outlet and form secondary channels in the ponds. During a very low tide, we deepened the mouth of the outlet channel by 1 m below high tide level to form a small waterfall when high tides receded. During successive tides, this one-step knickpoint deteriorated and formed a series of low rapids. With a steep gradient, the rapids retreated upstream into the ponds, first reopening the outlet channel and then carving new secondary channels in the pond mud flat. The excavation process of the outlet channel was repeated three times and was sufficient to effectively improve the hydrology of the entire pond system; allowing adequate flooding and draining of the mangrove ponds. Hydrology analysis tested by the Engelund-Hansen sediment transport formula established that the output of sediment from the ecosystem is greater than the input of sand into the mangroves. This is keeping the main channel continuously open. After eight years, tidal flow continues to keep the channels open; the salt crust has disappeared; the trees have recovered, and a large area of new vegetation has emerged.

  11. Restoration and recovery of hurricane-damaged mangroves using the knickpoint retreat effect and tides as dredging tools.

    PubMed

    Bashan, Yoav; Moreno, Manuel; Salazar, Bernardo G; Alvarez, Leonardo

    2013-02-15

    In 2001, a hurricane moved a large sand dune, blocking the sole outlet channel of a mangrove. In the absence of daily tidal flow, the two ponds containing the mangrove vegetation evaporated, the secondary drainage channels were lost, and a salt crust formed on the bed of the ponds. The mangrove lost most of its trees and the remaining suffered from osmotic shock that led to defoliation. Restoration involved creating a knickpoint retreat (waterfall retreat effect) and tidal flow as a dredging mechanism to restore the outlet and form secondary channels in the ponds. During a very low tide, we deepened the mouth of the outlet channel by 1 m below high tide level to form a small waterfall when high tides receded. During successive tides, this one-step knickpoint deteriorated and formed a series of low rapids. With a steep gradient, the rapids retreated upstream into the ponds, first reopening the outlet channel and then carving new secondary channels in the pond mud flat. The excavation process of the outlet channel was repeated three times and was sufficient to effectively improve the hydrology of the entire pond system; allowing adequate flooding and draining of the mangrove ponds. Hydrology analysis tested by the Engelund-Hansen sediment transport formula established that the output of sediment from the ecosystem is greater than the input of sand into the mangroves. This is keeping the main channel continuously open. After eight years, tidal flow continues to keep the channels open; the salt crust has disappeared; the trees have recovered, and a large area of new vegetation has emerged. PMID:23333638

  12. Timing of retreatment for patients with previously coiled or clipped intracranial aneurysms: Analysis of 156 patients with multiple treatments

    PubMed Central

    Okada, Takeshi; Ishikawa, Tatsuya; Moroi, Junta; Suzuki, Akifumi

    2016-01-01

    Background: Some patients require a second surgical intervention for recurrence of treated aneurysms, untreated aneurysms in patients with multiple lesions, or de novo aneurysm. This retrospective review of the data was undertaken to evaluate when retreatment is necessary after initial aneurysm treatment. Methods: Cerebral aneurysms in 1755 patients were treated via clipping or coiling between January 1995 and September 2012. Postoperative follow-up was performed at 6 months after treatment and was repeated every 12 months (or longer) after treatment using three-dimensional computed tomography angiography or magnetic resonance angiography. Results: A cumulative total of 156 patients (8.9%) (117 women, 39 men; mean age: 55.0 years; range: 25–79 years) needed retreatment for rupture or regrowth of aneurysm (n = 31; ruptured (R)/remaining unruptured (U), 26/5), formation of de novo aneurysm (n = 45; R/U, 23/22), known untreated aneurysm in patients with multiple lesions (n = 78; R/U, 5/73), and hemorrhage from undetected aneurysm (n = 2). The regrowth risk is higher after endovascular treatment than after craniotomy and clipping. Median time to retreatment was 187 months (range: 11–280 months) for regrowth, 165 months (range: 22–330 months) for de novo, and 24 months (range: 2.8–417 months) for known untreated aneurysm. Regrowth or known with subarachnoid hemorrhage were frequently treated within 2 years from initial treatment. Conclusions: Aneurysms with residua or untreated aneurysms in patients with multiple lesions carry a risk of bleeding during a relatively short period, whereas there is a small but significant risk of de novo formation and subsequent hemorrhage at over 10 years after previous treatment. PMID:26862460

  13. Issues and Structures for Sharing Medical Knowledge Among Decision-Making Systems: The 1989 Arden Homestead Retreat

    PubMed Central

    Clayton, Paul D.; Pryor, T. Allan; Wigertz, Ove B.; Hripcsak, George

    1989-01-01

    To address the issue of facilitating transfer and integration of the variety of computer-based programs which contain medical expertise, a retreat was held at Columbia University's Arden Homestead conference center June 16-18, 1989. The focus of this retreat was to explore ways in which the medical expertise contained in knowledge-based systems could be shared and expanded. During the three day meeting, the eighteen attendees from ten institutions discussed: (a) the need for better ways of mapping terminology used in one setting or program to terms with similar meaning that have been used in other programs, (b) the need for catalogues which list the variety of programs which are available, (c) a representational syntax and format for sharing modular medical knowledge, (d) the possibility of developing standards for interfacing program modules so that they could be “snapped” into place in a variety of systems, (e) methods for evaluating, validating and testing knowledge based systems, and (f) the legal and financial aspects of sharing systems which influence the care that is given to a patient. We emerged from the retreat with a feeling that there was an enthusiastic but not unanimous consensus that sharing should occur in order to advance the field of medical information systems. We accepted an initial version of a working document for the representation of Medical Logic Modules (MLM's), appointed leaders for subcommittees to address the issues which had surfaced and settled upon an approach for dealing with the legal and financial aspects of the sharing process.

  14. Potential of the solid-Earth response for limiting long-term West Antarctic Ice Sheet retreat

    NASA Astrophysics Data System (ADS)

    Konrad, Hannes; Sasgen, Ingo; Pollard, David; Klemann, Volker

    2016-04-01

    The West Antarctic Ice Sheet (WAIS) is assumed to be inherently unstable because it is grounded below sea level in a large part, where the bedrock deepens from today's grounding line towards the interior of the ice sheet. Idealized simulations have shown that bedrock uplift due to isostatic adjustment of the solid Earth and the associated sea-level fall may stop the retreat of such a marine-based ice sheet (Gomez et al., 2012). Here, we employ a coupled model for ice-sheet dynamics and solid-Earth dynamics, including a gravitationally consistent description of sea level, to investigate the influence of the viscoelastic Earth structure on the WAIS' future stability (Konrad et al. 2015). For this, we start from a steady-state condition for the Antarctic Ice Sheet close to present-day observations and apply atmospheric and oceanic forcing of different strength to initiate the retreat of the WAIS and investigate the effect of the viscoelastic deformation on the ice evolution for a range of solid-Earth rheologies. We find that the climate forcing is the primary control on the occurrence of the WAIS collapse. However, for moderate climate forcing and a weak solid-Earth rheology associated with the West Antarctic rift system (asthenosphere viscosities of 3x10^19 Pa s or less), we find that the combined effect of bedrock uplift and gravitational sea-level fall limits the retreat to the Amundsen Sea embayment on millennial time scales. In contrast, a stiffer Earth rheology yields a collapse under these conditions. Under a stronger climate forcing, weak Earth structures do not prevent the WAIS collapse; however, they produce a delay of up to 5000 years in comparison to a stiffer solid-Earth rheology. In an additional experiment, we test the impact of sea-level rise from an assumed fast deglaciation of the Greenland Ice Sheet. In cases when the climatic forcing is too weak to force WAIS collapse by itself, the additional rise in sea-level leads to disintegration of the WAIS

  15. The forest retreat of orpul: a holistic system of health care practiced by the Maasai tribe of East Africa.

    PubMed

    Burford, G; Rafiki, M Y; Ngila, L O

    2001-10-01

    The orpul healing retreat practiced by the Maasai of East Africa, in which decoctions of medicinal plants are taken with large quantities of meat, provides an example of a holistic indigenous system of primary health care. Most of the plants utilized in orpul medicines by the Maasai of Eluwaii, northern Tanzania, have already been empirically demonstrated to possess pharmacologic activities in vitro and/or in vivo. In addition, the songs, meditation, and prayers that form part of the orpul experience are likely to contribute significantly to recovery, particularly in the case of psychosomatic and stress-related illness. This community-based health practice should be preserved and evaluated.

  16. Influence of Ultrasonic Irrigation and Chloroform on Cleanliness of Dentinal Tubules During Endodontic Retreatment-An Invitro SEM Study

    PubMed Central

    Singhal, Anurag; Gurtu, Anuraag; Vinayak, Vineet

    2015-01-01

    Background Ultrasonic irrigation has been proved for its remarkable cleaning efficiency in the field of endodontics. But its role in endodontic re-treatment has been understated. There is not much data available to understand the effect of ultrasonic irrigation for the evaluation of cleanliness of dentinal tubules when it is used with or without chloroform, a gutta percha solvent during endodontic retreatment. Aim To compare the influence of ultrasonic irrigation with syringe irrigation on cleanliness of dentinal tubules after gutta perch removal for endodontic retreatment with or without the use of chloroform a gutta percha solvent using scanning electron microscope (SEM). Materials and Methods Freshly extracted 45 human mandibular premolar teeth for periodontal and orthodontic reasons were taken and were occlusally adjusted to a working length of 19 mm. The root canals of all teeth were prepared chemo mechanically to a master apical file size 40 and were divided in various groups. In Group 1 (n = 5; control group), the canals remained unfilled. In Groups 2 and 3 (n = 20 each), the canals were filled using lateral compaction with gutta-percha and AH plus sealer, removal of root fillings was undertaken after 2 weeks using Gates Glidden drills and H files without chloroform in Group 2 and with chloroform in group 3. The specimen of Group 2 and 3 were further divided into two subgroups I and II (n=10). In subgroup I, irrigation was done using side vented needles and sodium hypochlorite. In subgroup II irrigation was done using passive ultrasonic irrigation with sodium hypochlorite. Thereafter, the roots were split and the sections were observed under SEM. The number of occluded dentinal tubules /total number of dentinal tubules were calculated for the coronal, middle and apical third of each root half. Statistical analysis was performed using one-way ANOVA followed by Tukey’s test using standardized technique. Result Results indicated that the cleanest dentinal

  17. Reassessment of Colombia's tropical glaciers retreat rates: are they bound to disappear during the 2010-2020 decade?

    NASA Astrophysics Data System (ADS)

    Poveda, G.; Pineda, K.

    2009-12-01

    Clear-cut evidences of global environmental change in Colombia are discussed for diverse hydro-climatic records, and illustrated herein for increasing minimum temperature and decreasing annual maximum river flows records. As a consequence, eight tropical glaciers disappeared from the Colombian Andes during the 20th century, and the remaining six have experienced alarming retreat rates during the last decade. Here we report an updated estimation of retreat rates in the six remaining glacierized mountain ranges of Colombia for the period 1987-2007, using Landsat TM and TM+ imagery. Analyses are performed using detailed pre-processing, processing and post-processing satellite imagery techniques. Alarming retreat rates are confirmed in the studied glaciers, with an overall area shrinkage from 60 km2 in 2002, to 55.4 km2 in 2003, to less than 45 km2 in 2007. Assuming such linear loss rate (~3 km2 per year), for the near and medium term, the total collapse of the Colombian glaciers can be foreseen by 2022, but diverse physical mechanisms discussed herein would exacerbate the shrinkage processes, thus prompting us to forecast a much earlier deadline by the late 2010-2020 decade, long before the 100 years foreseen by the 2007 IPCC Fourth Assessment Report. This forecast demands detailed monitoring studies of mass and energy balances. Our updated estimations of Colombia's glacier retreat rates posse serious challenges for highly valuable ecosystem services, including water supply of several large cities and hundreds of rural settlements along the Colombian Andes, but also for cheap and renewable hydropower generation which provides 80% of Colombia's demand. Also, the identified changes threaten the survivability of unique and fragile ecosystems like paramos and cloud forests, in turn contributing to exacerbate social unrest and ongoing environmental problems in the tropical Andes which have been identified as the most critical hotspot for biodiversity on Earth. Colombia

  18. Retreatment of a Maxillary Lateral Incisor With Two Separate Root Canals Confirmed With Cone Beam Computed Tomography

    PubMed Central

    Aydemir, Seda; Helvacioglu-Yigit, Dilek; Sinanoglu, Alper; Ozel, Emre

    2015-01-01

    The purpose of this report is to present a rare case of a maxillary lateral incisor exhibiting two separate root canals confirmed by cone-beam computed tomography (CBCT). A 65-year-old female patient with an esthetic complaint regarding her maxillary left lateral incisor was referred to our clinic. During a radiographical examination, an endodontically treated root canal and an extra root canal with an apical lesion were observed. The retreatment was performed. CBCT findings confirmed the root canal mophology of the maxillary left lateral with two distinct canals. We conclude that the CBCT imaging is an adjunctive tool for better assessment of complex root canal systems. PMID:26015823

  19. Rate of bedrock channel incision by waterfall retreat and landscape response constrained by cosmogenic 3He, Kauai, Hawaii

    NASA Astrophysics Data System (ADS)

    Mackey, B. H.; Lamb, M. P.; Scheingross, J. S.; Farley, K. A.

    2011-12-01

    Channel incision and knickpoint retreat are the drivers of landscape evolution, yet we are still challenged to quantify the rate and processes by which rivers cut into rock. The Napali Coast on the northwestern side of Kauai, Hawaii, has multiple linear channels incising >200 m into the shield volcano surface. The channels have well-constrained initial conditions, including original topography, and relatively uniform layered basalt of known age (~4.5 Ma), which have attracted previous studies of channel evolution (e.g., Seidl et al., 1994, 1997). Many channels feature prominent waterfalls, although the mechanism of knickpoint initiation (submarine landslide vs cliff erosion) and subsequent retreat remain ambiguous. Motivated by these knowledge gaps and recent advances in cosmogenic helium geochronology, we revisited the Kaulaula Valley, a 9 km long narrow valley, beheaded on its upslope extent by the Waimea Canyon, and ending near the coast at the northern Mana Plain. Four kilometers up the canyon is a prominent 40 m high vertical knickpoint, dividing the valley into strongly contrasting geomorphic domains. The boulder-lined channel below the knickpoint is linear, steep (15%), and confined to a narrow valley with steep rocky cliffs (average slope 31°). Large, >2 m diameter angular boulders in the lower section of channel show evidence of mobility from debris flows. Above the knickpoint, average channel gradient is reduced (9%), bed load is much finer, and convex, soil-mantled hillslopes have a consistently lower mean slope of 18°. We constrained the exposure age of 18 features (in-channel boulders, stable boulders on terraces, and in-channel bedrock) along the length of the channel, by analysis of cosmogenic 3He in olivine phenocrysts. Cosmogenic exposure ages are oldest near the coast (80 ka) and systematically decrease with upstream distance towards the waterfall (< 5ka). In the upper section of channel, cosmogenic ages are approximately constant (10-20 ka

  20. Impact of retreatment with an artemisinin-based combination on malaria incidence and its potential selection of resistant strains: study protocol for a randomized controlled clinical trial

    PubMed Central

    2013-01-01

    Background Artemisinin-based combination therapy is currently recommended by the World Health Organization as first-line treatment of uncomplicated malaria. Recommendations were adapted in 2010 regarding rescue treatment in case of treatment failure. Instead of quinine monotherapy, it should be combined with an antibiotic with antimalarial properties; alternatively, another artemisinin-based combination therapy may be used. However, for informing these policy changes, no clear evidence is yet available. The need to provide the policy makers with hard data on the appropriate rescue therapy is obvious. We hypothesize that the efficacy of the same artemisinin-based combination therapy used as rescue treatment is as efficacious as quinine + clindamycin or an alternative artemisinin-based combination therapy, without the risk of selecting drug resistant strains. Design We embed a randomized, open label, three-arm clinical trial in a longitudinal cohort design following up children with uncomplicated malaria until they are malaria parasite free for 4 weeks. The study is conducted in both the Democratic Republic of Congo and Uganda and performed in three steps. In the first step, the pre-randomized controlled trial (RCT) phase, children aged 12 to 59 months with uncomplicated malaria are treated with the recommended first-line drug and constitute a cohort that is passively followed up for 42 days. If the patients experience an uncomplicated malaria episode between days 14 and 42 of follow-up, they are randomized either to quinine + clindamycin, or an alternative artemisinin-based combination therapy, or the same first-line artemisinin-based combination therapy to be followed up for 28 additional days. If between days 14 and 28 the patients experience a recurrent parasitemia, they are retreated with the recommended first-line regimen and actively followed up for another 28 additional days (step three; post-RCT phase). The same methodology is followed for each subsequent

  1. A Study of the "Inversion of Intensity" between Newborn and Preschool-Age Behavior

    ERIC Educational Resources Information Center

    Yang, Raymond K.; Halverson, Charles F., Jr.

    1976-01-01

    To test the inversion of intensity interpretation based on negative relations between newborn and pre-school intensity behaviors, 106 normal children were examined at the neonatal and pre-school periods. Interpretations of intensity behaviors at both periods and their longitudinal relations are discussed. (Author/SB)

  2. Comparison of Time Required by D-RaCe, R-Endo and Mtwo Instruments for Retreatment: An in vitro Study

    PubMed Central

    Garg, Akansha; Shetty, Shashit; Kumar, Sunil; Singh, Kamal Krishan; Garg, Amit

    2015-01-01

    Introduction: To evaluate and compare the amount of time required by three rotary NiTi instruments in removing gutta-percha from root canal during retreatment with hand file as control. Materials and Methods: Eighty human mandibular premolars with single straight root canals were prepared and obturated by cold lateral condensation with gutta-percha and AH Plus sealer. After two weeks, the 80 teeth were divided into one control group and 3 retreatment groups (n = 20 each). Gutta-percha was removed using H-files, the D-RaCe, or the Mtwo or the R-Endo retreatment systems. Retreatment time was calculated using stopwatch. Results: D-RaCe and Mtwo required significantly less time than R-Endo and hand file. Hand file took maximum time, which was significantly slower than all groups. However, D-RaCe and Mtwo retreatment time was statistically insignificant. Conclusion: D-RaCe and Mtwo remove gutta-percha faster than R-Endo and Hand files. PMID:25859525

  3. Fracture resistance exhibited by endodontically treated and retreated teeth shaped by ProTaper NEXT versus WaveOne: An in vitro study

    PubMed Central

    Khalap, Neha Deepak; Hegde, Vibha; Kokate, Sharad

    2015-01-01

    Aim: To compare the fracture resistance exhibited by teeth after primary endodontic treatment and retreatment. Materials and Methods: One hundred freshly extracted human teeth were selected. 20 samples served as control (untreated). Eighty experimental samples were divided into two groups (n = 40) for instrumentation using rotary Protaper NEXT (PTN) or reciprocating WaveOne (WO) files and obturated using warm lateral compaction. Half of the samples (n = 20) from each group were subjected to a load. The remaining half were subjected to retreatment using Protaper universal retreatment files (RFs) followed by a file larger than the master apical file used in groups 1 and 2 and reobturated. Group A: Control, Group B: PTN + obturation, Group C: WO + obturation, Group D: RF + PTN + obturation and Group E: RF + WO + obturation. The retreatment specimens were also subjected to load and the readings acquired were statistically analyzed. Result: When compared between the groups, control group exhibited the highest fracture resistance (P < 0.01). When multiple tests were performed, Group E exhibited significantly less fracture resistance (P < 0.01). Conclusion: Endodontic treatment and retreatment both results in lowering the fracture resistance of a tooth. PMID:26752838

  4. Beam Loss and Longitudinal Emittance Growth in SIS

    NASA Astrophysics Data System (ADS)

    Kirk, M.; Hofmann, I.; Boine-Frankenheim, O.; Spiller, P.; Hülsmann, P.; Franchetti, G.; Damerau, H.; König, H. Günter; Klingbeil, H.; Kumm, M.; Moritz, P.; Schütt, P.; Redelbach, A.

    2005-06-01

    Beam losses of several percent occur regularly in SIS. The onset occurs during the RF capture of the beam. Previous studies have revealed that the losses can come from the RF bucket at the start of acceleration being over filled due to the longitudinal bucket acceptance being too small, or due to the mismatch between the mean energy from the UNILAC and synchronous energy of the SIS. The beam losses as measured by a DC beam transformer however show in addition to the sharp initial drop, for the above reasons, a much slower decay in the beam intensity. The speculated cause comes from the incoherent transverse tune shift of the bunched beam, which forces particles into transverse resonant conditions. The longitudinal emittance growth is also another important issue for SIS. Past measurements from Schottky-noise pick-ups have shown a factor of 3-5 increase in the longitudinal emittance depending on the extraction energy; a large factor when compared against expectations from theory. These factors were calculated from the ratio between the normalized relative momentum spread of the DC beam before RF capture and after debunching. In this present work, tomographical techniques have been used to reconstruct the phasespace from a series of bunch profile measurements from a Beam Position Monitor (BPM). Therefore one can find the rate of growth in the longitudinal emittance from a series of high resolution BPM measurements along the RF ramp. Furthermore the initial phasespace density matrix from these reconstructions has been used to generate the initial population of macroparticles for the ESME longitudinal dynamics Particle-In-Cell code, thereby enabling a comparison between the longitudinal emittance growth of the beam under ideal conditions and that of the experiment. The longitudinal emittance growth (rms) during the acceleration (˜540ms) was approximately 20%, and that during the RF capture was estimated to have an upper limit of about 40%. Later measurements have also

  5. Observed high-altitude warming and snow cover retreat over Tibet and the Himalayas enhanced by black carbon aerosols

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Ramanathan, V.; Washington, W. M.

    2016-02-01

    Himalayan mountain glaciers and the snowpack over the Tibetan Plateau provide the headwater of several major rivers in Asia. In situ observations of snow cover extent since the 1960s suggest that the snowpack in the region have retreated significantly, accompanied by a surface warming of 2-2.5 °C observed over the peak altitudes (5000 m). Using a high-resolution ocean-atmosphere global climate model and an observationally constrained black carbon (BC) aerosol forcing, we attribute the observed altitude dependence of the warming trends as well as the spatial pattern of reductions in snow depths and snow cover extent to various anthropogenic factors. At the Tibetan Plateau altitudes, the increase in atmospheric CO2 concentration exerted a warming of 1.7 °C, BC 1.3 °C where as cooling aerosols cause about 0.7 °C cooling, bringing the net simulated warming consistent with the anomalously large observed warming. We therefore conclude that BC together with CO2 has contributed to the snow retreat trends. In particular, BC increase is the major factor in the strong elevation dependence of the observed surface warming. The atmospheric warming by BC as well as its surface darkening of snow is coupled with the positive snow albedo feedbacks to account for the disproportionately large role of BC in high-elevation regions. These findings reveal that BC impact needs to be properly accounted for in future regional climate projections, in particular on high-altitude cryosphere.

  6. Successful re-treatment with gefitinib for carcinomatous meningitis as disease recurrence of non-small-cell lung cancer.

    PubMed

    Hashimoto, Naozumi; Imaizumi, Kazuyoshi; Honda, Toyohiro; Kawabe, Tsutomu; Nagasaka, Tetsuro; Shimokata, Kaoru; Hasegawa, Yoshinori

    2006-09-01

    We report the case of a woman with gefitinib-sensitive lung adenocarcinoma, who was successfully re-treated with gefitinib for carcinomatous meningitis as the disease recurrence. The good response to gefitinib treatment was supported in part by the existence of epidermal growth factor receptor mutation in carcinoma cells in the specimen obtained from transbronchial lung biopsy, in which E709G in exon 18 and L858R in exon 21 were shown. Although carcinomatous meningitis had been well controlled by the treatment with gefitinib, serum carcinoembryonic antigen (CEA) level increased with re-growth of primary tumor and development of lymphangitic carcinomatosis. Immunohistochemical findings revealed de novo emergence of CEA-producing carcinoma cells in the biopsy specimen taken after recurrence of pulmonary lesion during re-treatment of gefitinib, but revealed little or no CEA expression in the specimen obtained at first presentation. These facts may suggest the possibility of oligo clonality of carcinoma cells in this case. PMID:16824645

  7. Committed retreat of Smith, Pope, and Kohler Glaciers over the next 30 years inferred by transient model calibration

    NASA Astrophysics Data System (ADS)

    Goldberg, D. N.; Heimbach, P.; Joughin, I.; Smith, B.

    2015-12-01

    A glacial flow model of Smith, Pope and Kohler Glaciers is calibrated by means of control methods against time varying, annually resolved observations of ice height and velocities, covering the period 2002 to 2011. The inversion - termed "transient calibration" - produces an optimal set of time-mean, spatially varying parameters together with a time-evolving state that accounts for the transient nature of observations and the model dynamics. Serving as an optimal initial condition, the estimated state for 2011 is used, with no additional forcing, for predicting grounded ice volume loss and grounding line retreat over the ensuing 30 years. The transiently calibrated model predicts a near-steady loss of grounded ice volume of approximately 21 km3 a-1 over this period, as well as loss of 33 km2 a-1 grounded area. We contrast this prediction with one obtained following a commonly used "snapshot" or steady-state inversion, which does not consider time dependence and assumes all observations to be contemporaneous. Transient calibration is shown to achieve a better fit with observations of thinning and grounding line retreat histories, and yields a quantitatively different projection with respect to ice volume loss and ungrounding. Sensitivity studies suggest large near-future levels of unforced, i.e., committed sea level contribution from these ice streams under reasonable assumptions regarding uncertainties of the unknown parameters.

  8. National Rural Health Mission--hopes and fears. Concerns about targeted sterilisation, retreat of the state and privatisation.

    PubMed

    Sundararaman, T; Jain, Kamlesh; Raman, V R; Singh, Premanjali Deepti

    2005-01-01

    The National Rural Health Mission (NRHM), launched by the present government as part of its honouring the Common Minimum Programme (CMP) commitment, had its content shaped by an active process of dialogue between many stakeholders. This article traces the contours of the discussions on three key concerns of civil society that influenced their contributions to the shaping of the National Rural Health Mission agenda. These three concerns were promotion of targeted sterilisation, a retreat of the state from its commitments to the health sector and that the NRHM agenda would lead to privatisation of public health facilities. Whereas fears on targeted sterilisation and retreat of the state may be unrealistic, there is a thrust to increased involvement of the private sector, which needs to be understood in its entirety. There is need for continued engagement byequity concerned public health professionals and health activists at all levels of implementation and not merely community monitoring to influence and shape the National Rural Health Mission in a pro-poor direction. PMID:16468280

  9. Imaging evidence for Hubbard Glacier advances and retreats since the last glacial maximum in Yakutat and Disenchantment Bays, Alaska

    NASA Astrophysics Data System (ADS)

    Zurbuchen, Julie M.; Gulick, Sean P. S.; Walton, Maureen A. L.; Goff, John A.

    2015-06-01

    High-resolution 2-D multichannel seismic data, collected during the 2012 UTIG-USGS National Earthquake Hazards Reduction Program survey of Disenchantment and Yakutat Bays in southeast Alaska, provide insight into their glacial history. These data show evidence of two unconformities, appearing in the form of channels, and are interpreted to be advance pathways for Hubbard Glacier. The youngest observable channel, thought to have culminated near the main phase of the Little Ice Age (LIA), is imaged in Disenchantment Bay and ends at a terminal moraine near Blizhni Point. An older channel, thought to be from an advance that culminated in the early phase of the LIA, extends from Disenchantment Bay into the northeastern edge of Yakutat Bay, turning southward at Knight Island and terminating on the southeastern edge of Yakutat Bay. Our interpretation is that Hubbard Glacier has repeatedly advanced around the east side of Yakutat Bay in Knight Island Channel, possibly due to the presence of Malaspina Glacier cutting off access to central Yakutat Bay during times of mutual advance. We observe two distinct erosional surfaces and retreat sequences of Hubbard Glacier in Yakutat Bay, supporting the hypothesis that minor glacial advances in fjords do not erode all prior sediment accumulations. Interpretation of chaotic seismic facies between these two unconformities suggests that Hubbard Glacier exhibits rapid retreats and that Disenchantment Bay is subject to numerous episodes of outburst flooding and morainal bank collapse. These findings also suggest that tidewater glaciers preferentially reoccupy the same channels in bay and marine settings during advances.

  10. Accelerating U.S. EHR Adoption: How to Get There From Here. Recommendations Based on the 2004 ACMI Retreat

    PubMed Central

    Middleton, Blackford; Hammond, W. Ed; Brennan, Patricia F.; Cooper, Gregory F.

    2005-01-01

    Despite growing support for the adoption of electronic health records (EHR) to improve U.S. healthcare delivery, EHR adoption in the United States is slow to date due to a fundamental failure of the healthcare information technology marketplace. Reasons for the slow adoption of healthcare information technology include a misalignment of incentives, limited purchasing power among providers, variability in the viability of EHR products and companies, and limited demonstrated value of EHRs in practice. At the 2004 American College of Medical Informatics (ACMI) Retreat, attendees discussed the current state of EHR adoption in this country and identified steps that could be taken to stimulate adoption. In this paper, based upon the ACMI retreat, and building upon the experiences of the authors developing EHR in academic and commercial settings we identify a set of recommendations to stimulate adoption of EHR, including financial incentives, promotion of EHR standards, enabling policy, and educational, marketing, and supporting activities for both the provider community and healthcare consumers. PMID:15492028

  11. Longitudinal dynamics in storage rings

    SciTech Connect

    Colton, E.P.

    1986-01-01

    The single-particle equations of motion are derived for charged particles in a storage ring. Longitudinal space charge is included in the potential assuming an infinitely conducting circular beam pipe with a distributed inductance. The framework uses Hamilton's equations with the canonical variables phi and W. The Twiss parameters for longitudinal motion are also defined for the small amplitude synchrotron oscillations. The space-charge Hamiltonian is calculated for both parabolic bunches and ''matched'' bunches. A brief analysis including second-harmonic rf contributions is also given. The final sections supply calculations of dynamical quantities and particle simulations with the space-charge effects neglected.

  12. Longitudinal instability of the forearm.

    PubMed

    Phadnis, J; Watts, A C

    2016-10-01

    The Essex Lopresti lesion is a rare triad of injury to the radial head, interosseous membrane of the forearm and distal radio-ulnar joint, which results in longitudinal instability of the radius. If unrecognized this leads to chronic pain and disability which is difficult to salvage. Early recognition and appropriate treatment is therefore desirable to prevent long-term problems. The aim of this article is to review the pathoanatomy of longitudinal radius instability and use the existing literature and authors' experience to provide recommendations for recognition and treatment of acute and chronic forearm instability, including description of the author's technique for interosseous membrane reconstruction. PMID:27628434

  13. Re-treatment rates after treatment with the Pipeline Embolization Device alone versus Pipeline and coil embolization of cerebral aneurysms: a single-center experience.

    PubMed

    Park, Min S; Nanaszko, Michael; Sanborn, Matthew R; Moon, Karam; Albuquerque, Felipe C; McDougall, Cameron G

    2016-07-01

    OBJECT The optimal strategy for use of the Pipeline Embolization Device (PED, ev3 Neurovascular) has not been clearly defined. The authors examined re-treatment rates after treatment with PED alone versus PED and adjunctive coil embolization (PED/coil). METHODS The authors retrospectively examined cerebral aneurysms treated with the PED from May 2011 to March 2014. Overall, 133 patients (25 men, 108 women; mean age 60.4 years, range 23-85 years) were treated for 140 aneurysms (mean size 11.8 ± 8.3 mm) requiring 224 PEDs (mean 1.7 PEDs per patient). Sixty-eight patients (13 men, 55 women) were treated with PED alone for 73 aneurysms (mean size 10.6 ± 9.2 mm) and 65 patients (12 men, 53 women) were treated with PED/coil for 67 aneurysms (mean size 12.8 ± 7.4 mm). RESULTS Eight aneurysms in 8 patients were re-treated in the PED-alone cohort versus only 1 aneurysm in 1 patient in the PED/coil cohort for re-treatment rates of 11.8% (8/68) and 1.5% (1/65), respectively (p = 0.03). Two patients in the PED-alone cohort were re-treated due to PED contraction, while the other 6 were re-treated for persistent filling of the aneurysms. The PED/coil patient experienced continued filling of a vertebrobasilar artery aneurysm. No aneurysms in either group ruptured after treatment. CONCLUSIONS Adjunctive coil embolization during flow diversion with the PED resulted in a significantly lower re-treatment rate compared with PED alone, suggesting an added benefit with adjunctive coil embolization. This result may provide the basis for future evaluation with randomized, controlled trials.

  14. New constraints on the timing of West Antarctic Ice Sheet retreat in the eastern Amundsen Sea since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Smith, James A.; Hillenbrand, Claus-Dieter; Kuhn, Gerhard; Klages, Johann Phillip; Graham, Alastair G. C.; Larter, Robert D.; Ehrmann, Werner; Moreton, Steven G.; Wiers, Steffen; Frederichs, Thomas

    2014-11-01

    Glaciers flowing into the Amundsen Sea Embayment (ASE) account for > 35% of the total discharge of the West Antarctic Ice Sheet (WAIS) and have thinned and retreated dramatically over the past two decades. Here we present detailed marine geological data and an extensive new radiocarbon dataset from the eastern ASE in order to constrain the retreat of the WAIS since the Last Glacial Maximum (LGM) and assess the significance of these recent changes. Our dating approach, relying mainly on the acid insoluble organic (AIO) fraction, utilises multi-proxy analyses of the sediments to characterise their lithofacies and determine the horizon in each core that would yield the most reliable age for deglaciation. In total, we dated 69 samples and show that deglaciation of the outer shelf was underway before 20,600 calibrated years before present (cal yr BP), reaching the mid-shelf by 13,575 cal yr BP and the inner shelf to within ca. 150 km of the present grounding line by 10,615 cal yr BP. The timing of retreat is broadly consistent with previously published radiocarbon dates on biogenic carbonate from the eastern ASE as well as AIO 14C ages from the western ASE and provides new constraints for ice sheet models. The overall retreat trajectory - slow on the outer shelf, more rapid from the middle to inner shelf - clearly highlights the importance of reverse bedslopes in controlling phases of accelerated groundling line retreat. Despite revealing these broad scale trends, the current dataset does not capture detailed changes in ice flow, such as stillstands during grounding line retreat (i.e., deposition of grounding zone wedges) and possible readvances as depicted in the geomorphological record.

  15. Geologic evidence of a leaky Antarctic Ice Sheet: Tracking meltwater influence on ice-sheet retreat in the Ross Sea, Antarctica since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Simkins, L.; Greenwood, S.; Anderson, J. B.; Prothro, L. O.; Halberstadt, A. R.; Stearns, L. A.; Demet, B. P.

    2015-12-01

    Meltwater at the base of an ice sheet has a significant influence on the flow dynamics and stability. Processes that lead to ice-sheet instability are at the forefront of research addressing uncertainty in the fate of modern ice sheets. A better understanding of subglacial meltwater is needed to assess the role of meltwater on ice-sheet instability and place modern observations of meltwater drainage into a longer-term context. Observations of subglacial channels and evidence of meltwater influence on ice-sheet dynamics are sparse in the geologic record around Antarctica. We present subglacial meltwater channels incised into the post-LGM sea scape of the Ross Sea continental shelf with clear relationships to glacial retreat landforms. We combine geomorphic and stratigraphic evidence to test the influence of meltwater on ice-sheet retreat during the last deglaciation. The channel systems are associated with small, closely-spaced ice-marginal landforms suggestive of rapid grounding line retreat. The channels were active during the late stages of retreat based on their positions in the southernmost portions of the troughs and cross-cutting relationships with glacial retreat landforms. Although channelized meltwater appears to be spatially limited, we have identified meltwater deposits within proximal grounding line facies from cores across the continental shelf in the western Ross Sea. Therefore, not only do we observe clear evidence of meltwater under the dwindling ice sheet, but basal meltwater in the Ross Sea is a pervasive feature and associated with geomorphic and sedimentologic expressions of rapid ice-sheet retreat. Ongoing work focuses on quantifying channel flow properties and reasonable meltwater production rates as well as further constraining evidence of meltwater in the Ross Sea and elsewhere around Antarctica.

  16. Retreating recurrent breast cancer with the same CMF-containing regimen used as adjuvant therapy. The International Breast Cancer Study Group.

    PubMed

    Castiglione-Gertsch, M; Tattersall, M; Hacking, A; Goldhirsch, A; Gudgeon, A; Gelber, R D; Lindtner, J; Coates, A; Collins, J; Isley, M; Senn, H J; Rudenstam, C M

    1997-12-01

    Breast cancer metastases appearing soon after adjuvant chemotherapy (within 12 months of its completion) are usually resistant to retreatment with the same cytotoxic agents, while relapses occurring later (beyond 12 months) regress when rechallenged with the same agents, showing similar response rates observed in non-pretreated patients with advanced disease. The International Breast Cancer Study Group (IBCSG) prospectively explored the efficacy of retreatment for patients upon relapse using the same therapy administered during the adjuvant programme. 87 patients previously treated with an adjuvant CMF (cyclophosphamide, methotrexate, 5-fluorouracil) combination chemotherapy (with or without the addition of low-dose prednisone and tamoxifen), who had measurable first breast cancer relapse, usually after at least 6 months of completion of the adjuvant treatment, were treated with CMF. Pretreatment consisted of 1-3 CMF courses in 27 patients and 4 or more courses in 60 patients. 17 patients were retreated with additional tamoxifen or had tamoxifen stopped at relapse. The data of these patients are shown separately. 47 of the 86 fully evaluable patients (55%) had an objective response, which was complete in 25 (29%). The dominant metastatic type and the number of involved sites were the most important factors influencing response to retreatment. Patients with soft tissue metastases had a high response rate (36/52, 69%) compared with those who had visceral involvement (9/24, 38%) or those with bony disease (2/10, 20%) (P = 0.002). In conclusion, response rates to retreatment with CMF were similar to those expected in a non-pretreated population. The patterns of relapse and the number of metastatic sites were the most important factors predicting response to retreatment, while treatment-free interval (usually longer than 6 months due to the study design) did not influence response rates. This study supports the hypothetic effectiveness of late reintroduction of adjuvant

  17. Shoreline retreat and sediment release in response to accelerating sea level rise: Measuring and modelling cliffline dynamics on the Suffolk Coast, UK

    NASA Astrophysics Data System (ADS)

    Brooks, S. M.; Spencer, T.

    2012-01-01

    Contemporary and historic data for shoreline retreat are used to evaluate and test a range of models that predict shoreline response to accelerating sea level rise. Models are tested against the known record of sea level rise acceleration over the twentieth century on the cliffline position of a series of soft rock cliffs located along the Suffolk Coast, UK. These cliffs have experienced high retreat rates throughout the twentieth century (between 2 and 4.5 m a - 1 ). The shoreline response model most suited to such an assessment is the SCAPE model, with a close fit between actual and modelled shoreline positions. Retreating shorelines also have associated changes in alongshore elevation, an aspect of shoreline retreat that has attracted little attention. Recently acquired IfSar data now permit detailed and accurate assessment of ground elevation from which the elevation of future clifflines can be derived. Combining elevation data with future shoreline retreat, also predicted using the SCAPE model, enables future sediment release from the cliffs to be evaluated. The methodology has the ability to take into account alongshore variability in retreat rates, where previously most studies focus upon a single rate for a given shoreline. This paper thereby identifies behaviour based around "switching on", "no change" and "switching off" in cliff systems. Volumes of sediment released in the twenty first century in response to accelerating sea level rise are likely to be considerable (up to 300 000 m 3 a - 1 ) for the Suffolk study area, and around an order of magnitude above the sediment release estimates for the early twentieth century under lower rates of sea level rise. The implications for shoreline protection offered from additional sediment in the nearshore zone are discussed.

  18. Longitudinally-vibrating surgical microelectrode

    NASA Technical Reports Server (NTRS)

    Feldstein, C.; Crawford, D.; Kawabus, E. W.

    1977-01-01

    Microelectrode attached to cone of loudspeaker imparting longitudinal vibrations, penetrates relatively tough tissue of arterial walls easier and with more precise depth control because dimpling is eliminated. Vibrating microelectrode has been successfully used to make accurate oxygen-content measurements in arterial walls.

  19. Longitudinal Studies of Spelling Development.

    ERIC Educational Resources Information Center

    Ellis, Nick

    Noting that proposed models of literacy development suggest that reading and writing mutually influence and grow from each other, this paper summarizes aspects of stage theories of literacy development and an integrative model, and considers how the model fared in empirical longitudinal tests. The paper begins with a summary of the modal aspects…

  20. Intensity Limitations in Fermilab Main Injector

    SciTech Connect

    Chan, W.

    1997-06-01

    The design beam intensity of the FNAL Main Injector (MI) is 3 x 10{sup 13} ppp. This paper investigates possible limitations in the intensity upgrade. These include the space charge, transition crossing, microwave instability, coupled bunch instability, resistive wall, beam loading (static and transient), rf power, aperture (physical and dynamic), coalescing, particle losses and radiation shielding, etc. It seems that to increase the intensity by a factor of two from the design value is straightforward. Even a factor of five is possible provided that the following measures are to be taken: an rf power upgrade, a {gamma}{sub t}-jump system, longitudinal and transverse feedback systems, rf feedback and feedforward, stopband corrections and local shieldings.

  1. Rate and style of ice stream retreat constrained by new surface-exposure ages: The Minch, NW Scotland

    NASA Astrophysics Data System (ADS)

    Bradwell, Tom; Small, David; Fabel, Derek; Dove, Dayton; Cofaigh, Colm O.; Clark, Chris; Consortium, Britice-Chrono

    2016-04-01

    Chronologically constrained studies of former ice-sheet extents and dynamics are important for understanding past cryospheric responses and modelling future ice-sheet and sea-level change. As part of the BRITICE-CHRONO project, we present new geomorphological and chronological data from a marine-terminating ice stream system in NW Europe that operated during the Late Weichselian Glaciation. A suite of 51 cosmogenic-nuclide exposure ages from ice sheet moraines and glacially transported boulders constrain the maximum extent of the ice sheet on the continental shelf (~28 ka BP) and its subsequent retreat, between ~27 and 16 ka BP, into a large marine embayment (ca. 7000 km2; the Minch, NW Scotland). Recently acquired swath bathymetry and acoustic sub-bottom profiler data reveal several large transverse grounding-zone wedges up to 40 m thick and 5 km wide with diagnostic acoustic-facies architecture. These seabed sediment wedges mark former quasi-stable positions of grounded marine-terminating ice-stream fronts; their size and thickness suggest long-lived stillstands of the order of centuries. Statistically significant clusters of exposure ages from glacial deposits on islands and intervening headlands shed important new light on the age of these marine grounding-zone wedges and, by inference, the rate and timing of Minch palaeo-ice stream retreat. We find strong evidence for episodic ice stream retreat on the continental shelf between ~28-24 ka BP, in the outer Minch between ~24-22 ka BP, and in the central Minch between 22-18.5 ka BP. In contrast, final ice stream deglaciation (<18 ka) across the deepest parts of the inner Minch embayment, was probably rapid and uninterrupted - with the ice sheet margin at or close to the present-day coastline in NW Scotland by 16.1 ka BP. It is hoped that these results will form the empirical basis for future ice-sheet modelling of this dynamically sensitive sector of the British-Irish Ice Sheet.

  2. Imaging Evidence for Hubbard Glacier Advances and Retreats since the Last Glacial Maximum in Disenchantment and Yakutat Bays, Alaska

    NASA Astrophysics Data System (ADS)

    Zurbuchen, J.; Gulick, S. P.; Levoir, M. A.; Goff, J. A.; Haeussler, P. J.

    2013-12-01

    As glaciers advance and retreat, they leave erosional surfaces, retreat sequences, morainal banks, and terminal moraines. These features can be imaged and interpreted in seismic reflection data to gain insight into ice routing, ice-sediment processes, and preserved glacial history. High-resolution 2-D multichannel seismic data gathered on the August 2012 UTIG-USGS National Earthquake Hazards Reduction Program survey of Disenchantment and Yakutat Bays have provided understanding of the advance pathways of the Hubbard Glacier and the glacial history of the bays. These data show evidence of three unconformities appearing in the form of channels and interpreted to be glacial advance and retreat paths. The youngest observable channel in Disenchantment Bay is ~2 km wide, forming morainal banks along the edges of the bay. The depth below modern sea level in two-way travel time (twtt) shallows from 510 ms in the middle of the bay to 400 ms ~4 km north of the entrance to Yakutat Bay. The sediment contained within the youngest channel measured from the seafloor thins southward from a twtt thickness of 260 ms to 115 ms. Beneath the youngest channel lies an older, 2.2 km-wide channel which is observed at ~580 ms below sea level, and is filled with sediments ranging in thickness from 480 ms to 180 ms at the terminus. This older channel extends from Disenchantment Bay into Yakutat Bay, staying to the northeast of Yakutat Bay, then turns southward at Knight Island and shallows to 450 ms twtt before forming a terminal moraine ~10 km north of the mouth of Yakutat Bay. Evidence for the third and oldest unconformity can only be seen within a very small number of short seismic lines in Disenchantment Bay. It is the largest of the channels, at ~3 km wide and 720 ms below modern sea level. The evidence of three nested unconformities suggests that the Hubbard Glacier has had at least three major advances in recent history. Radiocarbon dating of wooden branches in moraine deposits

  3. 14 CFR 27.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment Lights § 27.1389 Position... normal operating voltage of the rotorcraft. The light distribution and intensity of each position light... the longitudinal axis of the rotorcraft and perpendicular to the plane of symmetry of the...

  4. 14 CFR 27.1389 - Position light distribution and intensities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment Lights § 27.1389 Position... normal operating voltage of the rotorcraft. The light distribution and intensity of each position light... the longitudinal axis of the rotorcraft and perpendicular to the plane of symmetry of the...

  5. Visualization of longitudinal vortex flow in an enhanced heat transfer tube

    SciTech Connect

    Li, Xiao-wei; Yan, Huan; Meng, Ji-an; Li, Zhi-xin

    2007-05-15

    Longitudinal vortex flow was visualized in an enlarged DDIR tube (discrete double inclined ribs on the inner surface). The experiments were conducted in a water tunnel using dye injection. Two kinds of ribs with different widths were investigated. The visualizations showed counter rotating longitudinal vortex pairs formed by the discrete double inclined ribs. The vortex intensity increased with increasing Reynolds numbers while the length over which the vortices were observed along the flow direction decreased with increasing Reynolds numbers for Re = 1000-2000. The vortex intensity and vortex flow length were also strongly affected by the rib dimensions. (author)

  6. Sedimentology and chronology of the advance and retreat of the last British-Irish Ice Sheet on the continental shelf west of Ireland

    NASA Astrophysics Data System (ADS)

    Peters, Jared L.; Benetti, Sara; Dunlop, Paul; Ó Cofaigh, Colm; Moreton, Steven G.; Wheeler, Andrew J.; Clark, Christopher D.

    2016-05-01

    The last British-Irish Ice Sheet (BIIS) had extensive marine-terminating margins and was drained by multiple large ice streams and is thus a useful analogue for marine-based areas of modern ice sheets. However, despite recent advances from investigating the offshore record of the BIIS, the dynamic history of its marine margins, which would have been sensitive to external forcing(s), remain inadequately understood. This study is the first reconstruction of the retreat dynamics and chronology of the western, marine-terminating, margin of the last (Late Midlandian) BIIS. Analyses of shelf geomorphology and core sedimentology and chronology enable a reconstruction of the Late Midlandian history of the BIIS west of Ireland, from initial advance to final retreat onshore. Five AMS radiocarbon dates from marine cores constrain the timing of retreat and associated readvances during deglaciation. The BIIS advanced without streaming or surging, depositing a bed of highly consolidated subglacial traction till, and reached to within ∼20 km of the shelf break by ∼24,000 Cal BP. Ice margin retreat was likely preceded by thinning, grounding zone retreat and ice shelf formation on the outer shelf by ∼22,000 Cal BP. This ice shelf persisted for ≤2500 years, while retreating at a minimum rate of ∼24 m/yr and buttressing a >150-km long, 20-km wide, bathymetrically-controlled grounding zone. A large (∼150 km long), arcuate, flat-topped grounding-zone wedge, termed here the Galway Lobe Grounding-Zone Wedge (GLGZW), was deposited below this ice shelf and records a significant stillstand in BIIS retreat. Geomorphic relationships indicate that the BIIS experienced continued thinning during its retreat across the shelf, which led to increased topographic influence on its flow dynamics following ice shelf break up and grounding zone retreat past the GLGZW. At this stage of retreat the western BIIS was comprised of several discrete, asynchronous lobes that underwent several

  7. 14 CFR 23.145 - Longitudinal control.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Longitudinal control. 23.145 Section 23.145... Maneuverability § 23.145 Longitudinal control. (a) With the airplane as nearly as possible in trim at 1.3 VS1, it... multiengine airplanes, without the use of the primary longitudinal control system. (2) For...

  8. How do how internal and external processes affect the behaviors of coupled marsh mudflat systems; infill, stabilize, retreat, or drown?

    NASA Astrophysics Data System (ADS)

    Carr, J. A.; Mariotti, G.; Wiberg, P.; Fagherazzi, S.; McGlathery, K.

    2013-12-01

    Intertidal coastal environments are prone to changes induced by sea level rise, increases in storminess, and anthropogenic disturbances. It is unclear how changes in external drivers may affect the dynamics of low energy coastal environments because their response is non-linear, and characterized by many thresholds and discontinuities. As such, process-based modeling of the ecogeomorphic processes underlying the dynamics of these ecosystems is useful, not only to predict their change through time, but also to generate new hypotheses and research questions. Here, a three-point dynamic model was developed to investigate how internal and external processes affect the behavior of coupled marsh mudflat systems. The model directly incorporates ecogeomorphological feedbacks between wind waves, salt marsh vegetation, allochthonous sediment loading, tidal flat vegetation and sea level rise. The model was applied to examine potential trajectories of salt marshes on the Eastern seaboard of the United States, including those in the Plum Island Ecosystems (PIE), Virginia Coast Reserve (VCR) and Georgia Coastal Ecosystems (GCE) long term ecological research (LTER) sites. While these sites are undergoing similar rates of relative sea level rise (RSLR), they have distinct differences in site specific environmental drivers including tides, wind waves, allochthonous sediment supply and the presence or absence of seagrass. These differences lead to the emergence of altered behaviors in the coupled salt marsh-tidal flat system. For marsh systems without seagrass or significant riverine sediment supply, conditions similar to those at PIE, results indicated that horizontal and vertical marsh evolution respond in opposing ways to wave induced processes. Marsh horizontal retreat is triggered by large mudflats and strong winds, whereas small mudflats and weak winds reduce the sediment supply to the salt marsh, decreasing its capability to keep pace with sea level rise. Marsh expansion and

  9. The sanctuary of empathy and the invitation of engagement: psychic retreat, Kafka's "A Hunger Artist," and the psychoanalytic process.

    PubMed

    Karbelnig, Alan Michael

    2014-12-01

    As part of a broader scholarly and political effort to unify clinical psychoanalysis, the author argues that psychoanalysts' presence, engagement, and framing constitute the three overarching features of their work. Additionally, patients' propensity to turn inward, alternatively known as psychic retreat or narcissistic withdrawal, provides a similarly unifying way to view psychoanalytic patients. Narrowing the investigation to a phenomenological one, the author tapers the exploration further by studying the psychoanalytic process as it unfolds in real time. After addressing the problems of diffusion in professional identity and psychoanalytic theory that have plagued psychoanalysis from the start, the author presents three case examples into which he integrates Kafka's short story "A Hunger Artist." These vehicles are utilized to demonstrate how such nomenclature provides the basis for a more cohesive understanding of how psychoanalysts work. PMID:25490080

  10. Inadequacy of the current WHO re-treatment regimen in a central Siberian prison: treatment failure and MDR-TB.

    PubMed

    Kimerling, M E; Kluge, H; Vezhnina, N; Iacovazzi, T; Demeulenaere, T; Portaels, F; Matthys, F

    1999-05-01

    Multidrug-resistant tuberculosis (MDR-TB) threatens the progress of global control efforts. Prisons represent a high risk setting for development and transmission of MDR-TB. In a Siberian TB referral prison (Kemerovo region), the treatment failure rate is 35% (June 1996-March 1997), despite implementation of a strict DOTS program and use of the World Health Organization Category 2 re-treatment regimen for all new cases. Among 164 patients (December 1997-March 1998), initial resistance to isoniazid and rifampin is 22.6%. Such a rate is a warning call to reconsider prison control strategies, and importantly, to address the treatment regimens necessary to combat an institutional epidemic of MDR-TB. PMID:10331736

  11. Effectiveness of the Standard WHO Recommended Retreatment Regimen (Category II) for Tuberculosis in Kampala, Uganda: A Prospective Cohort Study

    PubMed Central

    Levin, Jonathan; Reilly, Nancy; Mumbowa, Francis; Dryden-Peterson, Scott; Nyakoojo, Grace; Fennelly, Kevin; Temple, Beth; Nakubulwa, Susan; Joloba, Moses L.; Okwera, Alphonse; Eisenach, Kathleen D.; McNerney, Ruth; Elliott, Alison M.; Ellner, Jerrold J.; Smith, Peter G.; Mugerwa, Roy D.

    2011-01-01

    Background Each year, 10%–20% of patients with tuberculosis (TB) in low- and middle-income countries present with previously treated TB and are empirically started on a World Health Organization (WHO)-recommended standardized retreatment regimen. The effectiveness of this retreatment regimen has not been systematically evaluated. Methods and Findings From July 2003 to January 2007, we enrolled smear-positive, pulmonary TB patients into a prospective cohort to study treatment outcomes and mortality during and after treatment with the standardized retreatment regimen. Median time of follow-up was 21 months (interquartile range 12–33 months). A total of 29/148 (20%) HIV-uninfected and 37/140 (26%) HIV-infected patients had an unsuccessful treatment outcome. In a multiple logistic regression analysis to adjust for confounding, factors associated with an unsuccessful treatment outcome were poor adherence (adjusted odds ratio [aOR] associated with missing half or more of scheduled doses 2.39; 95% confidence interval (CI) 1.10–5.22), HIV infection (2.16; 1.01–4.61), age (aOR for 10-year increase 1.59; 1.13–2.25), and duration of TB symptoms (aOR for 1-month increase 1.12; 1.04–1.20). All patients with multidrug-resistant TB had an unsuccessful treatment outcome. HIV-infected individuals were more likely to die than HIV-uninfected individuals (p<0.0001). Multidrug-resistant TB at enrolment was the only common risk factor for death during follow-up for both HIV-infected (adjusted hazard ratio [aHR] 17.9; 6.0–53.4) and HIV-uninfected (14.7; 4.1–52.2) individuals. Other risk factors for death during follow-up among HIV-infected patients were CD4<50 cells/ml and no antiretroviral treatment (aHR 7.4, compared to patients with CD4≥200; 3.0–18.8) and Karnofsky score <70 (2.1; 1.1–4.1); and among HIV-uninfected patients were poor adherence (missing half or more of doses) (3.5; 1.1–10.6) and duration of TB symptoms (aHR for a 1-month increase 1.9; 1.0–3

  12. The sanctuary of empathy and the invitation of engagement: psychic retreat, Kafka's "A Hunger Artist," and the psychoanalytic process.

    PubMed

    Karbelnig, Alan Michael

    2014-12-01

    As part of a broader scholarly and political effort to unify clinical psychoanalysis, the author argues that psychoanalysts' presence, engagement, and framing constitute the three overarching features of their work. Additionally, patients' propensity to turn inward, alternatively known as psychic retreat or narcissistic withdrawal, provides a similarly unifying way to view psychoanalytic patients. Narrowing the investigation to a phenomenological one, the author tapers the exploration further by studying the psychoanalytic process as it unfolds in real time. After addressing the problems of diffusion in professional identity and psychoanalytic theory that have plagued psychoanalysis from the start, the author presents three case examples into which he integrates Kafka's short story "A Hunger Artist." These vehicles are utilized to demonstrate how such nomenclature provides the basis for a more cohesive understanding of how psychoanalysts work.

  13. Presence of Candida Albicans in Root Canal System of Teeth Requiring Endodontic Retreatment with and without Periapical Lesions

    PubMed Central

    Ashraf, Hengameh; Samiee, Mohammad; Eslami, Gita; Ghodse Hosseini, Mohammad Reza

    2007-01-01

    INTRODUCTION: An important consideration in endodontic treatment is the elimination of microorganisms, including fungi, from the complex three- dimensional root canal system. Candida Albicans (CA) has a major role in endodontic treatment failure as the most important fungus isolated from the root canal system. The present study was carried out to evaluate the presence of CA in the teeth requiring endodontic retreatment, with or without periapical lesions. MATERIALS AND METHODS: This study was carried out on 60 root canals from human molars requiring endodontic retreatment. The root canals were randomly divided into two equal groups of 30 canals with versus without periapical lesions. Samples were collected from the root canals and cultured on MacConkey and blood agar culture media. The samples suspected of having CA were streaked on Sabouraud’s Dextrose Agar (SDA) and evaluated under a light microscope. Data was analyzed and compared using Chi- square and Kappa tests. RESULTS: CA was found in 11 patients (36.7%) with periapical lesions. In the patients without periapical lesions only 4 samples demonstrated CA in the root canal systems (13.3%). The difference between the two groups as to the presence of CA was statistically significant (p<0.037). In addition, evaluation of salivary samples revealed 15 cases (50%) of CA presence in the patients with periapical lesions and 16 cases (53.3%) of CA in the patients without periapical lesions, demonstrating no statistically significant difference between the two groups. CONCLUSION: Considering the fact that the presence of CA in the root canal systems of teeth with periapical lesions was more noticeable and statistically significant compared to the teeth without periapical lesions, the elimination of this microorganism from the root canal system, using appropriate intracanal solutions and medications is of utmost importance. PMID:24348654

  14. Linking Slab Break-Off, Hellenic Trench Retreat, and Uplift of the Central and Eastern Anatolian Plateaus

    NASA Astrophysics Data System (ADS)

    Schildgen, T. F.; Yildirim, C.; Cosentino, D.; Strecker, M. R.

    2015-12-01

    The Central and Eastern Anatolian plateaus are integral parts of the world's third largest orogenic plateau. Geophysical surveys that have provided insights into the crust, lithosphere, and mantle beneath Eastern Anatolia are now accompanied by recent work in Central Anatolia constraining uplift along its northern and southern margins. Together with predictions from geodynamic models, the observations can be integrated to identify probable mechanisms of plateau growth. A changeover from shortening to extension along the southern margin of Central Anatolia coeval with the start of uplift in the latest Miocene is likely associated with oceanic slab break-off following Arabia-Eurasia collision. This interpretation is supported by tomography, seismicity, and the pattern of uplift. Based on geological observations and model predictions, slab break-off likely occurred first beneath Eastern Anatolia in middle Miocene time and propagated westward toward Cyprus by the latest Miocene. Uplift at the northern margin of Central Anatolia appears to result from crustal shortening starting in the late Miocene, which has been linked to the broad restraining bend of the North Anatolian Fault (NAF). The uplift history of the Central Anatolian interior is unclear, although shortening was superseded by extension in the late Miocene. This change in the deformation style coincides with faster retreat of the Hellenic trench as well as uplift of the northern and southern margins of Central Anatolia. These different events may be linked, as faster retreat of the Hellenic trench has been predicted to occur after slab break-off, which could have induced extension of Central Anatolia and helped to form the NAF through accelerated westward escape of Anatolia. Overall, geochronologic evidence supports the hypothesis that tectonic and geodynamic plateau-forming activity throughout the Aegean-Anatolian domain in the Miocene defines a series of events that may all be linked to slab break-off.

  15. Observed high-altitude warming and snow cover retreat over Tibet and the Himalayas enhanced by black carbon aerosols

    DOE PAGES

    Xu, Y.; Ramanathan, V.; Washington, W. M.

    2016-02-05

    Himalayan mountain glaciers and the snowpack over the Tibetan Plateau provide the headwater of several major rivers in Asia. In situ observations of snow cover extent since the 1960s suggest that the snowpack in the region have retreated significantly, accompanied by a surface warming of 2–2.5 °C observed over the peak altitudes (5000 m). Using a high-resolution ocean–atmosphere global climate model and an observationally constrained black carbon (BC) aerosol forcing, we attribute the observed altitude dependence of the warming trends as well as the spatial pattern of reductions in snow depths and snow cover extent to various anthropogenic factors. At the Tibetanmore » Plateau altitudes, the increase in atmospheric CO2 concentration exerted a warming of 1.7 °C, BC 1.3 °C where as cooling aerosols cause about 0.7 °C cooling, bringing the net simulated warming consistent with the anomalously large observed warming. We therefore conclude that BC together with CO2 has contributed to the snow retreat trends. In particular, BC increase is the major factor in the strong elevation dependence of the observed surface warming. The atmospheric warming by BC as well as its surface darkening of snow is coupled with the positive snow albedo feedbacks to account for the disproportionately large role of BC in high-elevation regions. These findings reveal that BC impact needs to be properly accounted for in future regional climate projections, in particular on high-altitude cryosphere.« less

  16. Laser wakefield excitation and measurement by femtosecond longitudinal interferometry

    SciTech Connect

    Siders, C.W.; Le Blanc, S.P.; Fisher, D.; Tajima, T.; Downer, M.C.; Babine, A.; Stepanov, A.; Sergeev, A.

    1996-04-01

    Plasma density oscillations (Langmuir waves) in the wake of an intense (I{sub peak} {approximately} 3 {times} 10{sup 17}W/cm{sup 2}) laser pulse (100 fs) are measured with ultrafast time resolution using a longitudinal interferometric technique. Phase shifts consistent with large amplitude ({delta}n{sub e}/n{sub e} {approximately} 1) density waves at the electron plasma frequency were observed in a fully tunnel-ionized He plasma, corresponding to longitudinal electric fields of {approximately} 10 GV/m. Strong radial ponderomotive forces enhance the density oscillations. As this technique utilizes a necessary component of any laser-based plasma accelerator, it promises to be a powerful tool for on-line monitoring and control of future plasma-based particle accelerators.

  17. The Importance of Longitudinal Studies

    NASA Astrophysics Data System (ADS)

    Knezek, Patricia

    2014-01-01

    It has been eight years since the AAS Council unanimously endorsed the document, known as "Equity Now: The Pasadena Recommendations for Gender Equality in Astronomy," in January 2005. This document was the main product of the conference entitled “Women in Astronomy II: Ten Years After” (WIA II), held in June 2003 in Pasadena, CA. One of the key recommendations represented in that document was the need for a longitudinal study of astronomers. It was recognized that in order to understand our own field, how it is evolving, and the impact on individuals, we need to track people over time. I will discuss the fundamental questions that led to the recommendation, and set the stage for the current (ongoing) longitudinal study.

  18. LONGITUDINAL LASER WIRE AT SNS

    SciTech Connect

    Aleksandrov, Alexander V; Liu, Yun; Zhukov, Alexander P

    2014-01-01

    This paper describes a longitudinal H- beam profile scanner that utilizes laser light to detach convoy electrons and an MCP to collect and measure these electrons. The scanner is located in MEBT with H- energy of 2.5MeV and an RF frequency 402.5MHz. The picosecond pulsed laser runs at 80.5MHz in sync with the accelerator RF. The laser beam is delivered to the beam line through a 30m optical fiber. The pulse width after the fiber transmission measures about 10ps. Scanning the laser phase effectively allows measurements to move along ion bunch longitudinal position. We are able to reliably measure production beam bunch length with this method. The biggest problem we have encountered is background signal from electrons being stripped by vacuum. Several techniques of signal detection are discussed.

  19. A comparative evaluation of the canal centering ability of three rotary nickel-titanium retreatment systems in the mesio-buccal canals of mandibular first molars using computed tomography

    PubMed Central

    Gogulnath, Deenadhayalan; Rajan, Rajendran Mathan; Arathy, Ganesh; Kandaswamy, Deivanayagam

    2015-01-01

    Background: During endodontic retreatment, relative difficulty exists in removing the filling material and maintaining the canal anatomy. Usage of nickel-titanium (NiTi) rotary retreatment instruments is widely accepted, but there is a lack of adequate literature evidence about their canal centering ability. Aim: To compare the canal centering ability of rotary NiTi retreatment systems. Materials and Methods: Mandibular first molars with mesiobuccal canals with canal access angle of 20-40° were used. Canals prepared until ISO 25, 0.06 taper. Obturated with three different techniques lateral compaction, Thermafil, and Resilon/Epiphany. Retreatment was carried using three different systems ProTaper retreatment, Mtwo R and REndo. Specimens were subjected to computed tomography analysis at coronal, middle, and apical third of the root canal preobturation and postretreatment procedure. Statistical Analysis Used: One-way ANOVA and post-hoc Tukey test. Results: No statistically significant difference with three retreatment systems. Variation existed among all the subgroups at the coronal, middle, and apical third of the root canal. Conclusion: All retreatment systems with three obturation techniques showed eccentricity within acceptable limits. REndo, MtwoR showed better canal centering and ProTaper retreatment system showed tendency for eccentric canal preparation, especially in apical third. PMID:26180417

  20. Efficacy of Twisted File Adaptive, Reciproc and ProTaper Universal Retreatment instruments for root-canal-filling removal: A cone-beam computed tomography study.

    PubMed

    Akbulut, Makbule Bilge; Akman, Melek; Terlemez, Arslan; Magat, Guldane; Sener, Sevgi; Shetty, Heeresh

    2016-01-01

    The aim of this study was to evaluate the efficacy of Twisted File (TF) Adaptive, Reciproc, and ProTaper Universal Retreatment (UR) System instruments for removing root-canal-filling. Sixty single rooted teeth were decoronated, instrumented and obturated. Preoperative CBCT scans were taken and the teeth were retreated with TF Adaptive, Reciproc, ProTaper UR, or hand files (n=15). Then, the teeth were rescanned, and the percentage volume of the residual root-canal-filling material was established. The total time for retreatment was recorded, and the data was statistically analyzed. The statistical ranking of the residual filling material volume was as follows: hand file=TF Adaptive>ProTaper UR=Reciproc. The ProTaper UR and Reciproc systems required shorter periods of time for retreatment. Root canal filling was more efficiently removed by using Reciproc and ProTaper UR instruments than TF Adaptive instruments and hand files. The TF Adaptive system was advantageous over hand files with regard to operating time.

  1. Efficacy of ProTaper Retreatment System in Root Canals Obturated with Gutta-Percha Using Two Different Sealers and GuttaFlow.

    PubMed

    Siotia, Jaya; Acharya, Shashi Rashmi; Gupta, Sunil Kumar

    2011-01-01

    Objective. To compare the efficacy of ProTaper retreatment files in removing three different obturating materials. Study Design. Forty-five human, single-rooted premolars were divided into three experimental groups. Group 1 was obturated with gutta-percha and AH Plus sealer, Group 2 was obturated with gutta-percha and zinc oxide eugenol sealer, and Group 3 was obturated with GuttaFlow. Retreatment was done using the ProTaper universal rotary retreatment files. Root halves were visualized using magnifying loops at 3X magnification and optical stereomicroscope at 10X magnification. Images were analyzed using AutoCAD 2004 software to calculate area of the remaining debris in the canal. For statistical analysis were used variance test and ANOVA. Results. Total debris/canal area ratio between the three groups showed a statistically significant difference (P < 0.001). Conclusion. ProTaper retreatment system did not produce completely clean canals in any of the groups. However, it had the best efficacy towards removing silicon based obturating material GuttaFlow. PMID:22114598

  2. Parameterized Linear Longitudinal Airship Model

    NASA Technical Reports Server (NTRS)

    Kulczycki, Eric; Elfes, Alberto; Bayard, David; Quadrelli, Marco; Johnson, Joseph

    2010-01-01

    A parameterized linear mathematical model of the longitudinal dynamics of an airship is undergoing development. This model is intended to be used in designing control systems for future airships that would operate in the atmospheres of Earth and remote planets. Heretofore, the development of linearized models of the longitudinal dynamics of airships has been costly in that it has been necessary to perform extensive flight testing and to use system-identification techniques to construct models that fit the flight-test data. The present model is a generic one that can be relatively easily specialized to approximate the dynamics of specific airships at specific operating points, without need for further system identification, and with significantly less flight testing. The approach taken in the present development is to merge the linearized dynamical equations of an airship with techniques for estimation of aircraft stability derivatives, and to thereby make it possible to construct a linearized dynamical model of the longitudinal dynamics of a specific airship from geometric and aerodynamic data pertaining to that airship. (It is also planned to develop a model of the lateral dynamics by use of the same methods.) All of the aerodynamic data needed to construct the model of a specific airship can be obtained from wind-tunnel testing and computational fluid dynamics

  3. Modifying the Brain Activation of Poor Readers during Sentence Comprehension with Extended Remedial Instruction: A Longitudinal Study of Neuroplasticity

    ERIC Educational Resources Information Center

    Meyler, Ann; Keller, Timothy A.; Cherkassky, Vladimir L.; Gabrieli, John D. E.; Just, Marcel Adam

    2008-01-01

    This study used fMRI to longitudinally assess the impact of intensive remedial instruction on cortical activation among 5th grade poor readers during a sentence comprehension task. The children were tested at three time points: prior to remediation, after 100 h of intensive instruction, and 1 year after the instruction had ended. Changes in brain…

  4. Longitudinal Displacement of the Subtropical High in the Western Pacific in Summer and its Influence

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Sun, Shuqing

    2013-04-01

    Using the relative vorticity averaged over a certain area, a new index for measuring the longitudinal position of the subtropical high (SH) in the western Pacific is proposed to avoid the increasing trend of heights in the previous indices based on geopotential height. The years of extreme westward and eastward extension of SH using the new index are in good agreement with those defined by height index. There exists a distinct difference in large-scale circulation between the eastward and westward extension of SH under the new definition, which includes not only the circulation in the middle latitudes but also the flow in the lower latitudes. It seems that when the SH extends far to the east (west), the summer monsoon in the South China Sea is stronger (weaker) and established earlier (later). In addition, there exists a good relationship between the longitudinal position of SH and the summer rainfall in China. A remarkable negative correlation area appears in the Changjiang River valley, indicating that when the SH extends westward (eastward), the precipitation in that region increases (decreases). A positive correlation region is found in South China, showing the decrease of rainfall when the SH extends westward. On the other hand, the rainfall is heavier when the SH retreats eastward. However, the anomalous longitudinal position of SH is not significantly related to the precipitation in North China. The calculation of correlation coefficients between the index of longitudinal position of SH and surface temperature in China shows that a large area of positive values, higher than 0.6 in the center, covers the whole of North China, even extending eastward to the Korean Peninsula and Japan Islands when using NCEP/NCAR reanalysis data to do the correlation calculation. This means that when the longitudinal position of the SH withdraws eastward in summer, the temperature over North China is higher. On the other hand, when it moves westward, the temperature there is

  5. Longitudinal halo in beam bunches with self-consistent 6-D distributions

    NASA Astrophysics Data System (ADS)

    Gluckstern, R. L.; Fedotov, A. V.; Kurennoy, S. S.; Ryne, R. D.

    1998-11-01

    We have explored the formation of longitudinal and transverse halos in 3-D axisymmetric beam bunches by starting with a self-consistent 6-D phase space distribution. Stationary distributions allow us to study the halo development mechanism without being obscured by beam redistribution and its effect on halo formation. The beam is then mismatched longitudinally and/or transversely, and we explore the rate, intensity and spatial extent of the halos which form, as a function of the beam charge and the mismatches. We find that the longitudinal halo forms first because the longitudinal tune depression is more severe than the transverse one for elongated bunches and conclude that it plays a major role in halo formation.

  6. Retreatment with rituximab based on a treatment-to-target approach provides better disease control than treatment as needed in patients with rheumatoid arthritis: a retrospective pooled analysis

    PubMed Central

    Mease, Philip J.; Rubbert-Roth, Andrea; Curtis, Jeffrey R.; Müller-Ladner, Ulf; Gaylis, Norman B.; Williams, Sarah; Reynard, Mark; Tyrrell, Helen

    2011-01-01

    Objective. To assess the efficacy and safety profiles of two different rituximab retreatment regimens in patients with RA. Methods. Four hundred and ninety-three RA patients with an inadequate response to MTX recruited into rituximab Phase II/III studies received further courses of open-label rituximab based on two approaches: (i) treatment to target (TT): patients assessed 24 weeks after each course and retreated if not in remission [DAS in 28 joints based on ESR (DAS-28-ESR) ≥ 2.6]; (ii) treatment as needed (PRN): patients retreated at the physician’s discretion ≥24 weeks following the first course and ≥16 weeks following further courses, if both swollen and tender joint counts were ≥8. All courses consisted of i.v. rituximab 2 × 1000 mg 2 weeks apart plus MTX. Observed data were analysed according to treatment strategy. Results. Multiple courses of rituximab maintained or improved responses irrespective of regimen. TT provided tighter control of disease activity with significantly greater improvements in DAS-28-ESR and lower HAQ-disability index scores vs PRN. TT resulted in significantly more patients achieving major clinical response. PRN resulted in recurrence of disease symptoms between courses, with TT significantly reducing the incidence of RA flares. Despite more frequent retreatment with TT compared with PRN, the rates of serious adverse events and serious infections were comparable between regimens. Conclusions. Retreatment with rituximab based on 24-week evaluations and to a target of DAS-28-ESR remission leads to improved efficacy and tighter control of disease activity compared with PRN without a compromised safety profile. TT may be the preferable rituximab treatment regimen for patients with RA. PMID:21926153

  7. Study of streptomycin-induced ototoxicity: protocol for a longitudinal study.

    PubMed

    Adeyemo, Adebolajo A; Oluwatosin, Odunayo; Omotade, Olayemi O

    2016-01-01

    Hearing impairment is due to various causes including ototoxicity from aminoglycosides. The susceptibility to aminoglycosides increases in the presence of certain mitochondria gene mutations. There is unrestrained use of aminoglycosides in many developing nations which may worsen the burden of hearing impairment in these countries but there is lack of data to drive required policy changes. Streptomycin (an aminoglycoside) is part of the drug regimen in re-treatment of tuberculosis. Exploring the impact of streptomycin ototoxicity in tuberculosis patients provides a unique opportunity to study aminoglycoside ototoxicity within the population thus providing data that can inform policy. Also, since streptomycin ototoxicity could adversely affect treatment adherence in tuberculosis patients this study could enable better pre-treatment counseling with subsequent better treatment adherence. Patients on tuberculosis re-treatment will be recruited longitudinally from Direct Observation Therapy-Short course centers. A baseline full audiologic assessment will be done before commencement of treatment and after completion of treatment. Early detection of ototoxicity will be determined using the American Speech and Hearing Association criteria and genetic analysis to determine relevant mitochondria gene mutations will be done. The incidence of ototoxicity in the cohort will be analyzed. Both Kaplan-Meier survival curve and Cox proportional hazards tests will be utilized to determine factors associated with development of ototoxicity and to examine association between genotype status and ototoxicity. This study will provide data on the burden and associated predictors of developing aminoglycoside induced ototoxicity. This will inform public health strategies to regulate aminoglycoside usage and optimization of treatment adherence and the management of drug-induced ototoxicity among TB patients. Furthermore the study will describe mitochondrial gene mutations associated with

  8. Drift compression of an intense neutralized ion beam.

    PubMed

    Roy, P K; Yu, S S; Henestroza, E; Anders, A; Bieniosek, F M; Coleman, J; Eylon, S; Greenway, W G; Leitner, M; Logan, B G; Waldron, W L; Welch, D R; Thoma, C; Sefkow, A B; Gilson, E P; Efthimion, P C; Davidson, R C

    2005-12-01

    Longitudinal compression of a velocity-tailored, intense neutralized beam at 300 keV, 25 mA has been demonstrated. The compression takes place in a 1-2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhancing the beam peak current by a factor of 50 and producing a pulse duration of about 3 ns. This measurement has been confirmed independently with two different diagnostic systems.

  9. Drift compression of an intense neutralized ion beam

    SciTech Connect

    Roy, P.K.; Yu, S.S.; Henestroza, E.; Anders, A.; Bieniosek, F.M.; Coleman, J.; Eylon, S.; Greenway, W. G.; Leitner, M.; Logan, B.G.; Waldron, W.L.; Welch, D.R.; Thoma, C.; Sefkow, A.B.; Gilson, E.P.; Efthimion, P.C.; Davidson, R.C.

    2005-09-08

    Longitudinal compression of a velocity-tailored, intense neutralized K{sup +} beam at 300 keV, 25 mA has been demonstrated. The compression takes place in a 1-2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhancing the beam peak current by a factor of 50 and producing a pulse duration of about 3 ns. This measurement has been confirmed independently with two different diagnostic systems.

  10. NASA Planetary Science Summer School: Longitudinal Study

    NASA Astrophysics Data System (ADS)

    Giron, Jennie M.; Sohus, A.

    2006-12-01

    NASA’s Planetary Science Summer School is a program designed to prepare the next generation of scientists and engineers to participate in future missions of solar system exploration. The opportunity is advertised to science and engineering post-doctoral and graduate students with a strong interest in careers in planetary exploration. Preference is given to U.S. citizens. The “school” consists of a one-week intensive team exercise learning the process of developing a robotic mission concept into reality through concurrent engineering, working with JPL’s Advanced Project Design Team (Team X). This program benefits the students by providing them with skills, knowledge and the experience of collaborating with a concept mission design. A longitudinal study was conducted to assess the impact of the program on the past participants of the program. Data collected included their current contact information, if they are currently part of the planetary exploration community, if participation in the program contributed to any career choices, if the program benefited their career paths, etc. Approximately 37% of 250 past participants responded to the online survey. Of these, 83% indicated that they are actively involved in planetary exploration or aerospace in general; 78% said they had been able to apply what they learned in the program to their current job or professional career; 100% said they would recommend this program to a colleague.

  11. Analysis of the glacier retreat in the French Alps since the 1960s based on the new glacier inventory

    NASA Astrophysics Data System (ADS)

    Gardent, M.; Rabatel, A.; Dedieu, J. P.; Deline, P.; Schoeneich, P.

    2012-04-01

    One of the most obvious impacts of climate change in high mountain areas is the glacial retreat. Since the French glacier inventory carried out by R. Vivian in the late 1960s within the context of the WGI, there was no updated data from the overall French alpine glaciers. We present here the first results of a new diachronic inventory of the French alpine glaciers based on different sources. Glacier outlines were manually delineated using 1/25,000 topographic maps of the french National Geographical Institute (IGN) from the end of the 1960s, and IGN 50-cm-pixel orthophotographs from 2006 to 2009. For Landsat 5 TM images (30 m resolution) dating from 1985-1986, and Landsat 5 TM and Landsat 7 ETM+ images (30 and 15 m resolutions) dating from 2003, an automatic delineation with the common NDSI method was used to determine glacier limits. Each glacier has been individually checked, with a special care for debris covered and shadowed areas to adjust the delineation, using a 542 spectral bands combination. For compounded glaciers, the same limits were manually adjusted for each period. Data were integrated into a GIS and a database including all the common items (surface area, minimal and maximal elevations, aspect, debris covered area, slope…) was generated. Topographic parameters were extracted from the IGN DEM (resolution of 25 m) for the topographic maps and Landsat images from the mid-80s, and the ASTER GDEM (resolution of 30 m) for the Landsat images of the early 2000s and the orthophotographs. . Current extension of the 593 French alpine glaciers is about 275 km2. It is ~20 % less than in 1985-1986 (end of the last glacial advance period), when glacier extension was 340 km2, and ~26 % less than at the end of the 1960s, when glacier coverage was about 375 km2. Different trends are observed across the French Alps, with a stronger glacial retreat in the southern massifs: for instance, glacier shrinkage in the Ecrins massif is more than three times stronger than in

  12. Social Capital, Self-Esteem, and Use of Online Social Network Sites: A Longitudinal Analysis

    ERIC Educational Resources Information Center

    Steinfield, Charles; Ellison, Nicole B.; Lampe, Cliff

    2008-01-01

    A longitudinal analysis of panel data from users of a popular online social network site, Facebook, investigated the relationship between intensity of Facebook use, measures of psychological well-being, and bridging social capital. Two surveys conducted a year apart at a large U.S. university, complemented with in-depth interviews with 18 Facebook…

  13. Technology, Learning, and the Classroom: Longitudinal Evaluation of a Faculty Development Model

    ERIC Educational Resources Information Center

    Kaminski, Karen; Bolliger, Doris

    2012-01-01

    Technology, Learning, and the Classroom, a workshop designed to jump-start faculty's use of instructional technology in face-to-face classrooms, was offered as a week-long intensive workshop and once-a-week session over a semester. Faculty were interviewed five years after participation to determine the longitudinal effects, differences in opinion…

  14. Gender Differences in the Content of Preschool Children's Recollections: A Longitudinal Study

    ERIC Educational Resources Information Center

    Tõugu, Pirko; Tulviste, Tiia; Suits, Kristi

    2014-01-01

    Personal recollections constitute autobiographical memory that develops intensively during the preschool years. The two-wave longitudinal study focuses on gender differences in preschool children's independent recollections. The same children (N = 275; 140 boys, 135 girls) were asked to talk about their previous birthday and the past weekend…

  15. A Longitudinal Investigation of Employment among Low-Income Youth: Patterns, Predictors, and Correlates

    ERIC Educational Resources Information Center

    Purtell, Kelly M.; McLoyd, Vonnie C.

    2013-01-01

    Drawing on previous research linking patterns of adolescent employment--defined in terms of duration and intensity--to educational and occupational outcomes later in life (Staff & Mortimer, 2008), the present study (a) examined positive social behavior and academic variables as longitudinal predictors of patterns of adolescent employment during…

  16. Measurement of proton and anti-proton intensities in the Tevatron Collider

    SciTech Connect

    Stephen Pordes et al.

    2003-06-04

    This paper describes the techniques used to measure the intensities of the proton (p) and anti-proton ({bar p}) beams in the Tevatron collider. The systems provide simultaneous measurements of the intensity of the 36 proton and 36 antiproton bunches and their longitudinal profiles.

  17. The Effectiveness of ART Score in Selecting Patients for Transarterial Chemoembolization Retreatment: A Cohort Study in Taiwan.

    PubMed

    Tseng, Chi-Lung; Lai, Wei-Jen; Huang, Chun-Jui; Huang, Yi-Hsiang; Su, Chien-Wei; Lee, I-Cheng; Tseng, Hsiou-Shan; Li, Chung-Pin; Lee, Rheun-Chuan; Lin, Han-Chieh; Chao, Yee

    2015-11-01

    The major issue in selecting patients for transarterial chemoembolization (TACE) lies in determining the optimal number of TACE sessions that may benefit patients before switching to other therapies. This is often a subjective decision not based on any standardized protocol. The ART (Assessment for Retreatment with Transarterial chemoembolization) score was recently developed to determine patients who may benefit from multiple sessions of TACE for treatment of hepatocellular carcinoma. The primary aim of the study was to validate the ART score in a Taiwanese cohort. The secondary aims were to evaluate overall survival and clinical determinants of improved survival in patients treated with multiple TACE sessions. The ART score, clinical characteristics, and outcomes of 82 patients with hepatocellular carcinoma who received multiple TACE sessions at Taipei Veterans General Hospital from September 2007 to July 2013 were analyzed. Among the 82 patients evaluated, 69.5% (n = 57) had an ART score of 0 to 1.5 and 34.1% (n = 25) had a score of ≥2.5. The median overall survival was 23.1 months and the overall mortality rate was 62.2% (n = 51). The ART score was not associated with survival (P = 0.58). Multivariate Cox regression analysis revealed that tumor size >7.2 cm (hazard ratio 4.44, P < 0.001), aspartate transaminase (AST) level above 95 IU/L (hazard ratio 2.18, P = 0.02), AST increase more than 25% (hazard ratio 2.13, P = 0.02), 2nd/1st (pre-TACE) alpha-fetoprotein ratio (hazard ratio 1.40, P = 0.001), and lack of radiological response to TACE (hazard ratio 2.21, P = 0.02) were independent clinical determinants of survival. The ART score was not found to be effective in selecting patients for TACE retreatment in our Taiwanese cohort. Large tumor size, high AST level, high 2nd/1st (pre-TACE) alpha-fetoprotein ratio, AST increase >25%, and lack of radiological response to TACE were independently associated with shorter survival after TACE therapy.

  18. Volatile-rich Crater Interior Deposits in the Polar Regions of Mars: Evidence for Ice Cap Advance and Retreat

    NASA Technical Reports Server (NTRS)

    Russell, Patrick S.; Head, James W.; Hecht, Michael H.

    2003-01-01

    Many craters on Mars are partially filled by distinctive material emplaced by post-impact processes. This crater fill material is an interior mound which is generally separated from the walls of the crater by a trough that may be continuous along the crater circumference (i.e. a ring-shaped trough), or which may only partially contact the crater walls (i.e. a crescent-shaped trough). The fill deposit is frequently offset from the crater center and may be asymmetric in plan view. Populations of such craters include those in the circum-south polar cap region, in Arabia Terra, associated with the Medusae Fossae Formation, and in the northern lowlands proximal to the north polar cap. We focus on those craters in circumpolar regions and assess their relationship to polar cap advance and retreat, especially the possibility that fill material represents remnants of a formerly larger contiguous cap. Volatile-rich deposits have the property of being modifiable by the local stability of the solid volatile, which is governed by local energy balance. Here we test the hypothesis that asymmetries in volatile fill shape, profile, and center-location within a crater result from asymmetries in local energy balance within the crater, due mainly to variation of solar insolation and radiative effects of the crater walls over the crater interior. Model profiles of crater fill are compared with MOLA topographic profiles to assess this hypothesis. If asymmetry in morphology and location of crater fill are consistent with radiative-dominated asymmetries in energy budget within the crater, then 1) the volatile-rich composition of the fill is supported (this process should not be effective at shaping volcanic or sedimentary deposits), and 2) the dominant factor determining the observed shape of volatile-rich crater fill is the local radiative energy budget (and erosive processes such as eolian deflation are secondary or unnecessary). We also use a geographic and energy model approach to

  19. Spatiotemporal Trends of the Bay of Bengal Shoreline Retreat along the Sundarban Coasts and the Relevant Carbon Implications

    NASA Astrophysics Data System (ADS)

    Rahman, A. F.; Dragoni, D.; Elmasri, B.

    2010-12-01

    The coastal areas of the Bay of Bengal along the Ganges-Brahmaputra (GB) delta are low-lying and highly vulnerable to natural disasters, such as flooding and cyclones. The modern GB delta was formed within the large Bengal basin during the last 11,000 years, and it extends offshore in the Bay of Bengal. The coastal areas of this delta harbor the world’s largest continuous patch of mangrove forests, the Sundarbans, covering approximately one million hectares, ~60% of which is in Bangladesh and the rest is in India. Studies have shown that the GB delta is still undergoing accretion at a rate of up to 1.1 cm per year. But remote sensing studies have also indicated that the shoreline and shallow offshore areas of the western delta front are currently in a net erosional state at a rate of about 1.9 square km per year, with a coastline retreat of as much as 3-4 km since 1792. Other studies have quantified the land loss at 38 square km in since 1973. But no study to date has reported the details of spatiotemporal patterns of land loss along the Sundarbans coastline, or their drivers. Under global climate change and the related sea level rise, proper understanding of how the coastlines are changing and the drivers of those changes would be essential to mitigate the impacts on the coastal mangrove forests. In this study we used a time series of Landsat MSS and TM images from 1973 to 2010 to systematically explore the spatiotemporal distributions and trends of land loss along the Sundarbans coastline of Bangladesh and India. We also used data from a host of published studies on Bay of Bengal surface currents, cyclone tracks, sea level rise, monsoonal rainfalls, sediment flow, land subsidence and anthropogenic factors to deduct probable cause-effect relationships of the trends in coastal land loss. Finally we estimated the carbon loss of the mangrove forests due to the shoreline retreat, and using IPCC scenarios we predicted the future carbon implications of these mangrove

  20. Impact of Arctic sea-ice retreat on the recent change in cloud-base height during autumn

    NASA Astrophysics Data System (ADS)

    Sato, K.; Inoue, J.; Kodama, Y.; Overland, J. E.

    2012-12-01

    Cloud-base observations over the ice-free Chukchi and Beaufort Seas in autumn were conducted using a shipboard ceilometer and radiosondes during the 1999-2010 cruises of the Japanese R/V Mirai. To understand the recent change in cloud base height over the Arctic Ocean, these cloud-base height data were compared with the observation data under ice-covered situation during SHEBA (the Surface Heat Budget of the Arctic Ocean project in 1998). Our ice-free results showed a 30 % decrease (increase) in the frequency of low clouds with a ceiling below (above) 500 m. Temperature profiles revealed that the boundary layer was well developed over the ice-free ocean in the 2000s, whereas a stable layer dominated during the ice-covered period in 1998. The change in surface boundary conditions likely resulted in the difference in cloud-base height, although it had little impact on air temperatures in the mid- and upper troposphere. Data from the 2010 R/V Mirai cruise were investigated in detail in terms of air-sea temperature difference. This suggests that stratus cloud over the sea ice has been replaced as stratocumulus clouds with low cloud fraction due to the decrease in static stability induced by the sea-ice retreat. The relationship between cloud-base height and air-sea temperature difference (SST-Ts) was analyzed in detail using special section data during 2010 cruise data. Stratus clouds near the sea surface were predominant under a warm advection situation, whereas stratocumulus clouds with a cloud-free layer were significant under a cold advection situation. The threshold temperature difference between sea surface and air temperatures for distinguishing the dominant cloud types was 3 K. Anomalous upward turbulent heat fluxes associated with the sea-ice retreat have likely contributed to warming of the lower troposphere. Frequency distribution of the cloud-base height (km) detected by a ceilometer/lidar (black bars) and radiosondes (gray bars), and profiles of potential

  1. ASTER and Ground Observations of Vegetation Primary Succession and Habitat Development near Retreating Glaciers in Alaska and Nepal

    NASA Astrophysics Data System (ADS)

    Kargel, J. S.; Leonard, G. J.; Furfaro, R.

    2011-12-01

    Like active volcanoes, glaciers are among the most dynamic components of the Earth's solid surface. All of the main surface processes active in these areas have an ability to suddenly remake or "resurface" the landscape, effectively wiping the land clean of vegetation and habitats, and creating new land surface and aqueous niches for life to colonize and develop anew. This biological and geomorphological resurfacing may remove the soil or replace it with inorganic debris layers. The topographical, hydrological, and particle size-frequency characteristics of resurfaced deglaciated landscapes typically create a high density of distinctive, juxtaposed niches where differing plant communities may become established over time. The result is commonly a high floral and faunal diversity and fecundity of life habitats. The new diverse landscape continues to evolve rapidly as ice-cored moraines thaw, lakes drain or fill in with sediment, as fluvial dissection erodes moraine ridges, as deltaic sedimentation shifts, and other processes (coupled with primary succession) take place in rapid sequence. In addition, climate dynamics which may have caused the glaciers to retreat may continue. We will briefly explore two distinctive glacial environments-(1) the maritime Copper River corridor through the Chugach Mountains (Alaska), Allen Glacier, and the river's delta; and (2) Nepal's alpine Khumbu valley and Imja Glacier. We will provide an example showing how ASTER multispectral and stereo-derived elevation data, with some basic field-based constraints and observations, can be used to make automatic maps of certain habitats, including that of the Tibetan snowcock. We will examine geomorphic and climatic domains where plant communities are becoming established in the decades after glacier retreat and how these link to the snowcock habitat and range. Snowcock species have previously been considered to have evolved in close association with glacial and tectonic history of South and

  2. GIS-based analysis and modelling with empirical and remotely-sensed data on coastline advance and retreat

    NASA Astrophysics Data System (ADS)

    Ahmad, Sajid Rashid

    With the understanding that far more research remains to be done on the development and use of innovative and functional geospatial techniques and procedures to investigate coastline changes this thesis focussed on the integration of remote sensing, geographical information systems (GIS) and modelling techniques to provide meaningful insights on the spatial and temporal dynamics of coastline changes. One of the unique strengths of this research was the parameterization of the GIS with long-term empirical and remote sensing data. Annual empirical data from 1941--2007 were analyzed by the GIS, and then modelled with statistical techniques. Data were also extracted from Landsat TM and ETM+ images. The band ratio method was used to extract the coastlines. Topographic maps were also used to extract digital map data. All data incorporated into ArcGIS 9.2 were analyzed with various modules, including Spatial Analyst, 3D Analyst, and Triangulated Irregular Networks. The Digital Shoreline Analysis System was used to analyze and predict rates of coastline change. GIS results showed the spatial locations along the coast that will either advance or retreat over time. The linear regression results highlighted temporal changes which are likely to occur along the coastline. Box-Jenkins modelling procedures were utilized to determine statistical models which best described the time series (1941--2007) of coastline change data. After several iterations and goodness-of-fit tests, second-order spatial cyclic autoregressive models, first-order autoregressive models and autoregressive moving average models were identified as being appropriate for describing the deterministic and random processes operating in Guyana's coastal system. The models highlighted not only cyclical patterns in advance and retreat of the coastline, but also the existence of short and long-term memory processes. Long-term memory processes could be associated with mudshoal propagation and stabilization while short

  3. Evaluation of daily precipitation statistics and monsoon onset/retreat over western Sahel in multiple data sets

    NASA Astrophysics Data System (ADS)

    Diaconescu, Emilia Paula; Gachon, Philippe; Scinocca, John; Laprise, René

    2015-09-01

    The West Africa rainfall regime constitutes a considerable challenge for Regional Climate Models (RCMs) due to the complexity of dynamical and physical processes that characterise the West African Monsoon. In this paper, daily precipitation statistics are evaluated from the contributions to the AFRICA-CORDEX experiment from two ERA-Interim driven Canadian RCMs: CanRCM4, developed at the Canadian Centre for Climate Modelling and Analysis (CCCma) and CRCM5, developed at the University of Québec at Montréal. These modelled precipitation statistics are evaluated against three gridded observed datasets—the Global Precipitation Climatology Project (GPCP), the Tropical Rainfall Measuring Mission (TRMM), and the Africa Rainfall Climatology (ARC2)—and four reanalysis products (ECMWF ERA-Interim, NCEP/DOE Reanalysis II, NASA MERRA and NOAA-CIRES Twentieth Century Reanalysis). The two RCMs share the same dynamics from the Environment Canada GEM forecast model, but have two different physics' packages: CanRCM4 obtains its physics from CCCma's global atmospheric model (CanAM4), while CRCM5 shares a number of its physics modules with the limited-area version of GEM forecast model. The evaluation is focused on various daily precipitation statistics (maximum number of consecutive wet days, number of moderate and very heavy precipitation events, precipitation frequency distribution) and on the monsoon onset and retreat over the Sahel region. We find that the CRCM5 has a good representation of daily precipitation statistics over the southern Sahel, with spatial distributions close to GPCP dataset. Some differences are observed in the northern part of the Sahel, where the model is characterised by a dry bias. CanRCM4 and the ERA-Interim and MERRA reanalysis products overestimate the number of wet days over Sahel with a shift in the frequency distribution toward smaller daily precipitation amounts than in observations. Both RCMs and reanalyses have difficulties in reproducing

  4. Intensive Versus Non-Intensive Arabic.

    ERIC Educational Resources Information Center

    Hanna, Sami A.

    This paper investigates the difference in achievement among 20 University of Utah students of modern standard Arabic. One group of 11 students followed an intensive eight-week summer course, and a second group of nine students studied the same course during a regular academic year. Also reported on is the correlation between achievement and…

  5. Longitudinal study of fingerprint recognition

    PubMed Central

    Yoon, Soweon; Jain, Anil K.

    2015-01-01

    Human identification by fingerprints is based on the fundamental premise that ridge patterns from distinct fingers are different (uniqueness) and a fingerprint pattern does not change over time (persistence). Although the uniqueness of fingerprints has been investigated by developing statistical models to estimate the probability of error in comparing two random samples of fingerprints, the persistence of fingerprints has remained a general belief based on only a few case studies. In this study, fingerprint match (similarity) scores are analyzed by multilevel statistical models with covariates such as time interval between two fingerprints in comparison, subject’s age, and fingerprint image quality. Longitudinal fingerprint records of 15,597 subjects are sampled from an operational fingerprint database such that each individual has at least five 10-print records over a minimum time span of 5 y. In regard to the persistence of fingerprints, the longitudinal analysis on a single (right index) finger demonstrates that (i) genuine match scores tend to significantly decrease when time interval between two fingerprints in comparison increases, whereas the change in impostor match scores is negligible; and (ii) fingerprint recognition accuracy at operational settings, nevertheless, tends to be stable as the time interval increases up to 12 y, the maximum time span in the dataset. However, the uncertainty of temporal stability of fingerprint recognition accuracy becomes substantially large if either of the two fingerprints being compared is of poor quality. The conclusions drawn from 10-finger fusion analysis coincide with the conclusions from single-finger analysis. PMID:26124106

  6. Longitudinal study of fingerprint recognition.

    PubMed

    Yoon, Soweon; Jain, Anil K

    2015-07-14

    Human identification by fingerprints is based on the fundamental premise that ridge patterns from distinct fingers are different (uniqueness) and a fingerprint pattern does not change over time (persistence). Although the uniqueness of fingerprints has been investigated by developing statistical models to estimate the probability of error in comparing two random samples of fingerprints, the persistence of fingerprints has remained a general belief based on only a few case studies. In this study, fingerprint match (similarity) scores are analyzed by multilevel statistical models with covariates such as time interval between two fingerprints in comparison, subject's age, and fingerprint image quality. Longitudinal fingerprint records of 15,597 subjects are sampled from an operational fingerprint database such that each individual has at least five 10-print records over a minimum time span of 5 y. In regard to the persistence of fingerprints, the longitudinal analysis on a single (right index) finger demonstrates that (i) genuine match scores tend to significantly decrease when time interval between two fingerprints in comparison increases, whereas the change in impostor match scores is negligible; and (ii) fingerprint recognition accuracy at operational settings, nevertheless, tends to be stable as the time interval increases up to 12 y, the maximum time span in the dataset. However, the uncertainty of temporal stability of fingerprint recognition accuracy becomes substantially large if either of the two fingerprints being compared is of poor quality. The conclusions drawn from 10-finger fusion analysis coincide with the conclusions from single-finger analysis.

  7. Wave intensity wall analysis: a novel noninvasive method to measure wave intensity.

    PubMed

    Larsson, Matilda; Bjällmark, Anna; Lind, Britta; Balzano, Rita; Peolsson, Michael; Winter, Reidar; Brodin, Lars-Ake

    2009-09-01

    Wave intensity analysis is a concept providing information about the interaction of the heart and the vascular system. Originally, the technique was invasive. Since then new noninvasive methods have been developed. A recently developed ultrasound technique to estimate tissue motion and deformation is speckle-tracking echocardiography. Speckle tracking-based techniques allow for accurate measurement of movement and deformation variables in the arterial wall in both the radial and the longitudinal direction. The aim of this study was to test if speckle tracking-derived deformation data could be used as input for wave intensity calculations. The new concept was to approximate changes of flow and pressure by deformation changes of the arterial wall in longitudinal and radial directions. Flow changes (dU/dt) were approximated by strain rate (sr, 1/s) of the arterial wall in the longitudinal direction, whereas pressure changes (dP/dt) were approximated by sign reversed strain rate (1/s) in the arterial wall in the radial direction. To validate the new concept, a comparison between the newly developed Wave Intensity Wall Analysis (WIWA) algorithm and a commonly used and validated wave intensity system (SSD-5500, Aloka, Tokyo, Japan) was performed. The studied population consisted of ten healthy individuals (three women, seven men) and ten patients (all men) with coronary artery disease. The present validation study indicates that the mechanical properties of the arterial wall, as measured by a speckle tracking-based technique are a possible input for wave intensity calculations. The study demonstrates good visual agreement between the two systems and the time interval between the two positive peaks (W1-W2) measured by the Aloka system and the WIWA system correlated for the total group (r = 0.595, P < 0.001). The correlation for the diseased subgroup was r = 0.797, P < 0.001 and for the healthy subgroup no significant correlation was found (P > 0.05). The results of the

  8. Study of longitudinal dynamics in space-charge dominated beams

    NASA Astrophysics Data System (ADS)

    Tian, Kai

    Modern accelerator applications, such as heavy ion fusion drivers, pulsed neutron sources, electron injectors for high-energy linear colliders, and X-ray Free Electron Lasers, demand beams with high intensity, low emittance and small energy spread. At low (non-relativistic) energies, the "electrostatic", collective interactions from space-charge forces existing in such intense beams play the dominant role; we characterize these beams as space-charge dominated beams. This dissertation presents numerous new findings on the longitudinal dynamics of a space-charge dominated beam, particularly on the propagation of density perturbations. In order to fully understand the complex physics of longitudinal space-charge waves, we combine the results of theory, computer simulation, and experiment. In the Long Solenoid Experimental system (LSE), with numerous diagnostic tools and techniques, we have, for the first time, experimentally measured the detailed energy profiles of longitudinal space-charge waves at different locations, both near the beam source and at the end of the transport system. Along with the current profiles, we have a complete set of experimental data for the propagation of space-charge waves. We compare these measured results to a 1-D theory and find better agreement for beams with perturbations in the linear regime, where the perturbation strength is less than 10%, than those with nonlinear perturbations. Using fast imaging techniques that we newly developed, we have, for the first time, obtained the progressive time-resolved images of longitudinal slices of a space-charge dominated beam. These images not only provide us time-resolved transverse density distribution of the beam, but also enable us to take time-resolved transverse phase space measurement using computerized tomography. By combining this information with the longitudinal energy measurement, we have, for the first time, experimentally constructed the full 6-D phase space. Part of the results

  9. Retreatment With Varenicline for Smoking Cessation in Smokers Who Have Previously Taken Varenicline: A Randomized, Placebo-Controlled Trial

    PubMed Central

    Gonzales, D; Hajek, P; Pliamm, L; Nackaerts, K; Tseng, L-J; McRae, T D; Treadow, J

    2014-01-01

    The efficacy and safety of retreatment with varenicline in smokers attempting to quit were evaluated in this randomized, double-blind, placebo-controlled, multicenter trial (Australia, Belgium, Canada, the Czech Republic, France, Germany, the United Kingdom, and the United States). Participants were generally healthy adult smokers (≥10 cigarettes/day) with ≥1 prior quit attempt (≥2 weeks) using varenicline and no quit attempts in ≤3 months; they were randomly assigned (1:1) to 12 weeks' varenicline (n = 251) or placebo (n = 247) treatment, with individual counseling, plus 40 weeks' nontreatment follow-up. The primary efficacy end point was the carbon monoxide–confirmed (≤10 ppm) continuous abstinence rate for weeks 9–12, which was 45.0% (varenicline; n = 249) vs. 11.8% (placebo; n = 245; odds ratio: 7.08; 95% confidence interval: 4.34, 11.55; P < 0.0001). Common varenicline group adverse events were nausea, abnormal dreams, and headache, with no reported suicidal behavior. Varenicline is efficacious and well tolerated in smokers who have previously taken it. Abstinence rates are comparable with rates reported for varenicline-naive smokers. PMID:24911368

  10. Transforming the self and healing the body through the use of testimonies in a divine retreat center, Kerala.

    PubMed

    Jansen, Eva; Lang, Claudia

    2012-06-01

    In this article, we analyze the collective healing process that takes place on a weekly basis in the Divine Retreat Center (DRC) in Muringoor, Kerala. We argue that disease in the DRC is understood either as a psycho-somatic or as a spirito-somatic phenomenon. In contrast to other Charismatic communities, however, the body is the locus on which the medical effects of the healing become visible. The whole process is divided into several phases: First, there is a cleansing and disengagement procedure that aims to purify and liberate the participants through confession and counseling. Thereafter comes a climatic phase of personal emptying, transition and re-orientation during which the healing itself takes place. The procedure is finally completed with the person being spiritually "refilled" by the Holy Spirit. The dominant recurring element in the whole process is the continuous statement of healing "testimonies." As an integral part of the healing procedure, these statements are used to share personal experiences among the participants in the center. They are produced in a strict format in order to be spread far beyond through various media (TV, newspaper, Internet, etc.). They thereby constitute a speech genre that follows specific rules and patterns. Through shaping one's own biography in the frame of the testimonies, so we argue, the actual transformation of the self and therefore the miracle healing takes place.