263 research outputs found

    The Stationary Phase Method for a Wave Packet in a Semiconductor Layered System. The applicability of the method

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    Using the formal analysis made by Bohm in his book, {\em "Quantum theory"}, Dover Publications Inc. New York (1979), to calculate approximately the phase time for a transmitted and the reflected wave packets through a potential barrier, we calculate the phase time for a semiconductor system formed by different mesoscopic layers. The transmitted and the reflected wave packets are analyzed and the applicability of this procedure, based on the stationary phase of a wave packet, is considered in different conditions. For the applicability of the stationary phase method an expression is obtained in the case of the transmitted wave depending only on the derivatives of the phase, up to third order. This condition indicates whether the parameters of the system allow to define the wave packet by its leading term. The case of a multiple barrier systems is shown as an illustration of the results. This formalism includes the use of the Transfer Matrix to describe the central stratum, whether it is formed by one layer (the single barrier case), or two barriers and an inner well (the DBRT system), but one can assume that this stratum can be comprise of any number or any kind of semiconductor layers.Comment: 15 pages, 4 figures although figure 4 has 5 graph

    Hypersensitivity in molar incisor hypomineralization: Superficial infiltration treatment

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    To date, there are no standardized protocols available in the literature for hypersensitivity treatment in molar incisor hypomineralization (MIH) patients. The aim of this study was to evaluate the efficacy of erosion\u2013infiltration treatments with resin in children with a strong hypersensitivity and also to develop a minimally invasive diagnostic\u2013therapeutic pathway for young MIH patients. Patients with clinical signs of MIH were enrolled according to international guidelines. A total of 42 patients (8\u201314 years old) with sensitivity of at least one molar and patients with post eruptive enamel fractures, but without dentin involvement or cavitated carious lesions were selected. A single superficial infiltration treatment with ICON (DMG, Germany) was performed with a modified etching technique. Sensitivity was tested with the Schiff Scale and Wong Baker Face Scale and was repeated at 12 months follow\u2010up. All patients reported lower sensitivity values at the end of the treatment. Significant differences of sensitivity according to the Schiff scale were reported between T0 and all subsequent follow\u2010ups, p < 0.05. The treatment of erosion infiltration with ICON resin is a minimally invasive preventive treatment that significantly improves the problem of hypersensitivity in permanent molars with MIH

    The XMM-Newton survey of the Small Magellanic Cloud: XMMUJ005011.2-730026 = SXP214, a Be/X-ray binary pulsar

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    In the course of the XMM-Newton survey of the Small Magellanic Cloud (SMC), a region to the east of the emission nebula N19 was observed in November 2009. To search for new candidates for high mass X-ray binaries the EPIC PN and MOS data of the detected point sources were investigated and their spectral and temporal characteristics identified. A new transient (XMMUJ005011.2-730026= SXP214) with a pulse period of 214.05 s was discovered; the source had a hard X-ray spectrum with power-law index of ~0.65. The accurate X-ray source location permits the identification of the X-ray source with a ~15th magnitude Be star, thereby confirming this system as a new Be/X-ray binary.Comment: 8 pages 11 figures. Accepted for publication in MNRA

    MAGIC Upper Limits for two Milagro-detected, Bright Fermi Sources in the Region of SNR G65.1+0.6

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    We report on the observation of the region around supernova remnant G65.1+0.6 with the stand-alone MAGIC-I telescope. This region hosts the two bright GeV gamma-ray sources 1FGL J1954.3+2836 and 1FGL J1958.6+2845. They are identified as GeV pulsars and both have a possible counterpart detected at about 35 TeV by the Milagro observatory. MAGIC collected 25.5 hours of good quality data, and found no significant emission in the range around 1 TeV. We therefore report differential flux upper limits, assuming the emission to be point-like (<0.1 deg) or within a radius of 0.3 deg. In the point-like scenario, the flux limits around 1 TeV are at the level of 3 % and 2 % of the Crab Nebula flux, for the two sources respectively. This implies that the Milagro emission is either extended over a much larger area than our point spread function, or it must be peaked at energies beyond 1 TeV, resulting in a photon index harder than 2.2 in the TeV band.Comment: 8 pages, 3 figures, 1 tabl

    Dexketoprofen/tramadol: randomised double-blind trial and confirmation of empirical theory of combination analgesics in acute pain

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    Background: Combination analgesics are effective in acute pain, and a theoretical framework predicts efficacy for combinations. The combination of dexketoprofen and tramadol is untested, but predicted to be highly effective. Methods: This was a randomised, double-blind, double-dummy, parallel-group, placebo-controlled, single-dose trial in patients with moderate or severe pain following third molar extraction. There were ten treatment arms, including dexketoprofen trometamol (12.5 mg and 25 mg) and tramadol hydrochloride (37.5 mg and 75 mg), given as four different fixed combinations and single components, with ibuprofen 400 mg as active control as well as a placebo control. The study objective was to evaluate the superior analgesic efficacy and safety of each combination and each single agent versus placebo. The primary outcome was the proportion of patients with at least 50 % max TOTPAR over six hours. Results: 606 patients were randomised and provided at least one post-dose assessment. All combinations were significantly better than placebo. The highest percentage of responders (72 %) was achieved in the dexketoprofen trometamol 25 mg plus tramadol hydrochloride 75 mg group (NNT 1.6, 95 % confidence interval 1.3 to 2.1). Addition of tramadol to dexketoprofen resulted in greater peak pain relief and greater pain relief over the longer term, particularly at times longer than six hours (median duration of 8.1 h). Adverse events were unremarkable. Conclusions: Dexketoprofen trometamol 25 mg combined with tramadol hydrochloride 75 mg provided good analgesia with rapid onset and long duration in a model of moderate to severe pain. The results of the dose finding study are consistent with pre-trial calculations based on empirical formulae

    Efficacy of the Vaccine Candidate Based on the P0 Peptide against Dermacentor nitens and Ixodes ricinus Ticks

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    (This article belongs to the Collection Advances in Tick Research)The control of ticks through vaccination offers a sustainable alternative to the use of chemicals that cause contamination and the selection of resistant tick strains. However, only a limited number of anti-tick vaccines have reached commercial realization. In this sense, an antigen effective against different tick species is a desirable target for developing such vaccines. A peptide derived from the tick P0 protein (pP0) conjugated to a carrier protein has been demonstrated to be effective against the Rhipicephalus microplus, Rhipicephalus sanguineus, and Amblyomma mixtum tick species. The aim of this work was to assess the efficacy of this peptide when conjugated to the Bm86 protein against Dermacentor nitens and Ixodes ricinus ticks. An RNAi experiment using P0 dsRNA from I. ricinus showed a dramatic reduction in the feeding of injected female ticks on guinea pigs. In the follow-up vaccination experiments, rabbits were immunized with the pP0-Bm86 conjugate and challenged simultaneously with larvae, nymphs, and the adults of I. ricinus ticks. In the same way, horses were immunized with the pP0-Bm86 conjugate and challenged with D. nitens larva. The pP0-Bm86 conjugate showed efficacies of 63% and 55% against I. ricinus and D. nitens ticks, respectively. These results, combined with previous reports of efficacy for this conjugate, show the promising potential for its development as a broad-spectrum anti-tick vaccine.This research was funded by the Center for Genetic Engineering and Biotechnology, Havana, Cuba, the Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal, and the Czech Science Foundation grant no. 20-05736S. Mobility was supported by the CYTED Network INCOGARR 110RT0541.info:eu-repo/semantics/publishedVersio

    Kepler observations of variability in B-type stars

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    The analysis of the light curves of 48 B-type stars observed by Kepler is presented. Among these are 15 pulsating stars, all of which show low frequencies characteristic of SPB stars. Seven of these stars also show a few weak, isolated high frequencies and they could be considered as SPB/beta Cep hybrids. In all cases the frequency spectra are quite different from what is seen from ground-based observations. We suggest that this is because most of the low frequencies are modes of high degree which are predicted to be unstable in models of mid-B stars. We find that there are non-pulsating stars within the beta Cep and SPB instability strips. Apart from the pulsating stars, we can identify stars with frequency groupings similar to what is seen in Be stars but which are not Be stars. The origin of the groupings is not clear, but may be related to rotation. We find periodic variations in other stars which we attribute to proximity effects in binary systems or possibly rotational modulation. We find no evidence for pulsating stars between the cool edge of the SPB and the hot edge of the delta Sct instability strips. None of the stars show the broad features which can be attributed to stochastically-excited modes as recently proposed. Among our sample of B stars are two chemically peculiar stars, one of which is a HgMn star showing rotational modulation in the light curve.Comment: 19 pages, 11 figures, 4 table

    Dentin dysplasia type I: a challenge for treatment with dental implants

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    <p>Abstract</p> <p>Background</p> <p>Dentin dysplasia type I is characterized by a defect of dentin development with clinical normal appearance of the permanent teeth but no or only rudimentary root formation. Early loss of all teeth and concomitant underdevelopment of the jaws are challenging for successful treatment with dental implants.</p> <p>Methods</p> <p>A combination of sinus lifting and onlay bone augmentation based on treatment planning using stereolithographic templates was used in a patient with dentin dysplasia type I to rehabilitate the masticatory function.</p> <p>Results</p> <p>(i) a predisposition for an increased and accelerated bone resorption was observed in our patient, (ii) bone augmentation was successful using a mixture of allogenic graft material with autogenous bone preventing fast bone resorption, (iii) surgical planning, based on stereolithographic models and surgical templates, facilitated the accurate placement of dental implants.</p> <p>Conclusion</p> <p>Bony augmentation and elaborate treatment planning is helpful for oral rehabilitation of patients with dentin dysplasia type I.</p

    Variable stars across the observational HR diagram

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    An overview of pulsating variable stars across the observational Hertzprung-Russel (HR) diagram is presented, together with a summary of their global properties. The HR diagram is presented with a third colour-coded dimension, visualizing the fraction of variable, the amplitude of variability or the period of variability. The distribution of variable stars in the other observational diagrams, such as the Period-Amplitude diagram, is also presented. Some of the progresses performed in the field of variable stars during the last decade are briefly summarized, and future projects that will improve our knowledge of variable stars are mentioned.Comment: 21 pages, 9 figure
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