2,631 research outputs found

    The Effect of EDTA in Attachment Gain and Root Coverage

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    Root surface biomodification using low pH agents such as citric acid and tetracycline has been proposed to enhance root coverage following connective tissue grafting. The authors hypothesized that root conditioning with neutral pH edetic acid would improve vertical recession depth, root surface coverage, pocket depth, and clinical attachment levels. Twenty teeth in 10 patients with Miller class I and II recession were treated with connective tissue grafting. The experimental sites received 24% edetic acid in sterile distilled water applied to the root surface for 2 minutes before grafting. Controls were pretreated with only sterile distilled water. Measurements were evaluated before surgery and 6 months after surgery. Analysis of variance was used to determine differences between experimental and control groups. We found significant postoperative improvements in vertical recession depth, root surface coverage, and clinical attachment levels in test and control groups, compared to postoperative data. Pocket depth differences were not significant (P\u3c.01)

    Sexual Reward and Depression

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    Sexual behavior in male rats is a complex rewarding behavior and many neurotransmitters and neuropeptides play an important role in mediation of sexual performance, motivation and reward. The hypothalamic neuropeptide orexin has been shown play a key role in reward associated with food and drugs of abuse, but the role of this neuropeptide in control of sexual performance, motivation and reward is currently unclear. First, it was shown that orexin neurons in the hypothalamus are activated during sexual performance and reward. Next, using cell specific lesions of orexin neurons it was demonstrated that orexin is involved in arousal and anxiety, but is not critical for sexual performance or motivation. Moreover, orexin was shown to play a critical role in control of sexual reward. Thus, these studies provided novel information regarding a role for orexin in this natural reward behavior. Recent studies have shown that sexual behavior in male rats causes neuroplasticity in the mesolimbic system, enhanced psychostimulant-induced locomotor activity and drug craving. The latter of which is dependent on a period of abstinence from sexual behavior, suggesting an increased vulnerability for addiction following loss of sexual reward. Thus, the next goal of this thesis determined if abstinence from sexual behavior also leads increased vulnerability for other disorders related to reward processing, specifically depression-like behavior. It was demonstrated that a prolonged (28 day) but not short (1 or 7 day) period of abstinence causes depression-like behavior in sexually experienced male rats seen as increased passive stress coping behaviors and anhedonia. Development of depression-like behavior was associated with increased levels of corticotropin releasing factor mRNA in the paraventricular nucleus of the hypothalamus and increased hypothalamic-pituitary-adrenal axis activity in response to an acute stressor. Thus, these studies provide novel information on behavioral and neuroplastic alterations observed following a prolonged period of abstinence from mating and suggest that loss of sexual reward in male rats may be a paradigm to study depression following loss of social reward in humans

    Effective-one-body waveforms for binary neutron stars using surrogate models

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    Gravitational-wave observations of binary neutron star systems can provide information about the masses, spins, and structure of neutron stars. However, this requires accurate and computationally efficient waveform models that take <1s to evaluate for use in Bayesian parameter estimation codes that perform 10^7 - 10^8 waveform evaluations. We present a surrogate model of a nonspinning effective-one-body waveform model with l = 2, 3, and 4 tidal multipole moments that reproduces waveforms of binary neutron star numerical simulations up to merger. The surrogate is built from compact sets of effective-one-body waveform amplitude and phase data that each form a reduced basis. We find that 12 amplitude and 7 phase basis elements are sufficient to reconstruct any binary neutron star waveform with a starting frequency of 10Hz. The surrogate has maximum errors of 3.8% in amplitude (0.04% excluding the last 100M before merger) and 0.043 radians in phase. The version implemented in the LIGO Algorithm Library takes ~0.07s to evaluate for a starting frequency of 30Hz and ~0.8s for a starting frequency of 10Hz, resulting in a speed-up factor of ~10^3 - 10^4 relative to the original Matlab code. This allows parameter estimation codes to run in days to weeks rather than years, and we demonstrate this with a Nested Sampling run that recovers the masses and tidal parameters of a simulated binary neutron star system.Comment: 17 pages, 11 figures, submitted to PR

    Plausible fluorescent Ly-alpha emitters around the z=3.1 QSO0420-388

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    We report the results of a survey for fluorescent Ly-alpha emission carried out in the field surrounding the z=3.1 quasar QSO0420-388 using the FORS2 instrument on the VLT. We first review the properties expected for fluorescent Ly-alpha emitters, compared with those of other non-fluorescent Ly-alpha emitters. Our observational search detected 13 Ly-alpha sources sparsely sampling a volume of ~14000 comoving Mpc^3 around the quasar. The properties of these in terms of i) the line equivalent width, ii) the line profile and iii) the value of the surface brightness related to the distance from the quasar, all suggest that several of these may be plausibly fluorescent. Moreover, their number is in good agreement with the expectation from theoretical models. One of the best candidates for fluorescence is sufficiently far behind QSO0420-388 that it would imply that the quasar has been active for (at least) ~60 Myrs. Further studies on such objects will give information about proto-galactic clouds and on the radiative history (and beaming) of the high-redshift quasars.Comment: 10 pages, 4 figures.Update to match the version published on ApJ 657, 135, 2007 March

    Interpreting doubly special relativity as a modified theory of measurement

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    In this article we develop a physical interpretation for the deformed (doubly) special relativity theories (DSRs), based on a modification of the theory of measurement in special relativity. We suggest that it is useful to regard the DSRs as reflecting the manner in which quantum gravity effects induce Planck-suppressed distortions in the measurement of the "true" energy and momentum. This interpretation provides a framework for the DSRs that is manifestly consistent, non-trivial, and in principle falsifiable. However, it does so at the cost of demoting such theories from the level of "fundamental" physics to the level of phenomenological models -- models that should in principle be derivable from whatever theory of quantum gravity one ultimately chooses to adopt.Comment: 18 pages, plain LaTeX2

    The role of mediterranean fruit tree orchards and vineyards in maintaining the traditional agricultural landscape

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    The Mediterranean area represents one of the most suitable and diversified environments for horticultural crops, being this propriety well expressed in the commonly accepted definition of “Mediterranean cultivated garden”. In Italy, fruit crops have been in the past introduced and expanded in different environments depending on the species and adaptability to the physiographic characteristics of the regions. The climate and the diversity of environmental contexts, the specificity of soils, the plasticity of the cultivated genotypes, have allowed a tight and typical relationship among land and farmers. Since the past centuries olive and fruit orchards, vineyards and Citrus plantations have represented the typicity of the Italian rural landscape. The physiognomy of tree cropping systems has been changed rapidly starting from half of the past century owing to the introduction of new genetic resources, the change in the concepts of quality, the modernization and intensification of the agronomical techniques, resulting in loss of environmental and biological diversity. Nonetheless, some historic fruit orchards and vineyards have survived. The research is focused: a) on the recognition and mapping of the traditional landscapes of fruit crops in two representative Mediterranean regions; b) on the identification of their typological traits; c) on the definition of their environmental and technical sustainability based on an interdisciplinary methodology. Through a multi-criterial analysis it was possible to recognize and measure the sustainability of these cropping models and their ecological function, turning into preservation of environmental resources, environmental quality and quality of life. The study also underlined the crucial role of the traditional agricultural landscapes in the maintenance of local identity, history and economy. By representing a cultural heritage, traditional agricultural landscapes and traditional farming might justify preservation and valorisation actions

    Quantum Breathing of an Impurity in a One-dimensional Bath of Interacting Bosons

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    By means of time-dependent density-matrix renormalization-group (TDMRG) we are able to follow the real-time dynamics of a single impurity embedded in a one-dimensional bath of interacting bosons. We focus on the impurity breathing mode, which is found to be well-described by a single oscillation frequency and a damping rate. If the impurity is very weakly coupled to the bath, a Luttinger-liquid description is valid and the impurity suffers an Abraham-Lorentz radiation-reaction friction. For a large portion of the explored parameter space, the TDMRG results fall well beyond the Luttinger-liquid paradigm.Comment: 10 pages, 7 figures, main text and supplementary material merged in a single PRB style documen

    The general exact solution for the many moments macroscopic approach to extended thermodynamics of polyatomic gases

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    A new model for Polyatomic and for Dense Gases has been proposed in literature in the last five years in the framework of Extended Thermodynamics. The case with an arbitrary but fixed number of moments has been recently studied, both with the kinetic approach than with the macroscopic approach; this last one is more general and includes the results of the kinetic approach only as a particular case. \\ Scope of the "closure problem" is to find the expression of some arbitrary functions which appear in the balance equations. Up to now only a recurrence procedure has been published which outlines how to find the solution of this problem with the macroscopic approach; by using this procedure, a numberable set of solutions has been found and written explicitly, while we find here the most general exact solution. It is determined except for some arbirary terms and it is interesting that these terms appear also in the 24 moments model; so we find here that they are transmitted from the model with 24 moments to those with an arbitrary number of moments, without any further arbitrary term
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