491 research outputs found

    Symbiotic Solitons in Heteronuclear Multicomponent Bose-Einstein condensates

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    We show that bright solitons exist in quasi-one dimensional heteronuclear multicomponent Bose-Einstein condensates with repulsive self-interaction and attractive inter-species interaction. They are remarkably robust to perturbations of initial data and collisions and can be generated by the mechanism of modulational instability. Some possibilities for control and the behavior of the system in three dimensions are also discussed

    Pair-breaking effect on mesoscopic persistent currents

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    We consider the contribution of superconducting fluctuations to the mesoscopic persistent current (PC) of an ensemble of normal metallic rings, made of a superconducting material whose low bare transition temperature Tc0T^{0}_{c} is much smaller than the Thouless energy EcE_{c}. The effect of pair breaking is introduced via the example of magnetic impurities. We find that over a rather broad range of pair-breaking strength ℏ/τs\hbar/\tau_{s}, such that Tc0≲ℏ/τs≲EcT_c^0 \lesssim \hbar/\tau_s \lesssim E_c, the superconducting transition temperature is normalized down to minute values or zero while the PC is hardly affected. This may provide an explanation for the magnitude of the average PC's in copper and gold, as well as a way to determine their Tc0T^0_c's. The dependence of the current and the dominant superconducting fluctuations on EcτsE_c\tau_s and on the ratio between EcE_c and the temperature is analyzed. The measured PC's in copper (gold) correspond to Tc0T^0_c of a few (a fraction of) mK

    The First Detections of the Extragalactic Background Light at 3000, 5500, and 8000A (II): Measurement of Foreground Zodiacal Light

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    We present a measurement of the absolute surface brightness of the zodiacal light (3900-5100A) toward a fixed extragalactic target at high ecliptic latitude based on moderate resolution (~1.3A per pixel) spectrophotometry obtained with the du Pont 2.5m telescope at Las Campanas Observatory in Chile. This measurement and contemporaneous Hubble Space Telescope data from WFPC2 and FOS comprise a coordinated program to measure the mean flux of the diffuse extragalactic background light (EBL). The zodiacal light at optical wavelengths results from scattering by interplanetary dust, so that the zodiacal light flux toward any extragalactic target varies seasonally with the position of the Earth. This measurement of zodiacal light is therefore relevant to the specific observations (date and target field) under discussion. To obtain this result, we have developed a technique that uses the strength of the zodiacal Fraunhofer lines to identify the absolute flux of the zodiacal light in the multiple-component night sky spectrum. Statistical uncertainties in the result are 0.6% (1 sigma). However, the dominant source of uncertainty is systematic errors, which we estimate to be 1.1% (1 sigma). We discuss the contributions included in this estimate explicitly. The systematic errors in this result contribute 25% in quadrature to the final error in our coordinated EBL measurement, which is presented in the first paper of this series.Comment: Accepted for publication in ApJ, 22 pages using emulateapj.sty, version with higher resolution figures available at http://www.astro.lsa.umich.edu/~rab/publications.html or at http://nedwww.ipac.caltech.edu/level5/Sep01/Bernstein2/frames.htm

    Effect of pair-breaking on mesoscopic persistent currents well above the superconducting transition temperature

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    We consider the mesoscopic normal persistent current (PC) in a very low-temperature superconductor with a bare transition temperature Tc0T_c^0 much smaller than the Thouless energy EcE_c. We show that in a rather broad range of pair-breaking strength, Tc0≲ℏ/τs≲EcT_c^0 \lesssim \hbar/\tau_s \lesssim E_c, the transition temperature is renormalized to zero, but the PC is hardly affected. This may provide an explanation for the magnitude of the average PC's in the noble metals, as well as a way to determine their Tc0T_c^0's.Comment: 4 pages, 2 figure

    Production of Lambda and Sigma^0 hyperons in proton-proton collisions

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    This paper reports results on simultaneous measurements of the reaction channels pp -> pK+\Lambda and pp -> pK+\Sigma^0 at excess energies of 204, 239, and 284 MeV (\Lambda) and 127, 162, and 207 MeV (\Sigma^0). Total and differential cross sections are given for both reactions. It is concluded from the measured total cross sections that the high energy limit of the cross section ratio is almost reached at an excess energy of only about 200 MeV. From the differential distributions observed in the overall CMS as well as in the Jackson and helicity frames, a significant contribution of interfering nucleon resonances to the \Lambda production mechanism is concluded while resonant \Sigma^0-production seems to be of lesser importance and takes place only through specific partial waves of the entrance channel. The data also indicate that kaon exchange plays a minor role in the case of \Lambda- but an important role for \Sigma^0-production. Thus the peculiar energy dependence of the \Lambda-to-\Sigma^0 cross section ratio appears in a new light as its explanation requires more than mere differences between the p\Lambda and the p\Sigma^0 final state interaction. The data provide a benchmark for theoretical models already available or yet to come.Comment: 18 pages, 10 figures; accepted by The European Physical Journal A (EPJ A

    Youth in transition:Study protocol of a prospective cohort study into the long-term course of addiction, mental health problems and social functioning in youth entering addiction treatment

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    BACKGROUND: Substance use disorders (SUDs) are prevalent in the general population, tend to follow a chronic course, are associated with many individual and social problems, and often have their onset in adolescence. However, the knowledge base from prospective population surveys and treatment-outcome studies on the course of SUD in adolescents is limited at best. The present study aims to fill this gap and focuses on a subgroup that is particularly at risk for chronicity: adolescents in addiction treatment. We will investigate the rate of persistent SUD and its predictors longitudinally from adolescence to young adulthood among youth with DSM-5 SUD from the start of their addiction treatment to 2 and 4 years following treatment-entry. In addition to SUD, we will investigate the course of comorbid mental disorders, social functioning, and quality of life and their association with SUD over time. METHODS/DESIGN: In a naturalistic, multi-center prospective cohort design, we will include youths (n = 420), who consecutively enter addiction treatment at ten participating organizations in the Netherlands. Inclusion is prestratified by treatment organization, to ensure a nationally representative sample. Eligible youths are 16 to 22 years old and seek help for a primary DSM-5 cannabis, alcohol, cocaine or amphetamine use disorder. Assessments focus on lifetime and current substance use and SUD, non-SUD mental disorders, family history, life events, social functioning, treatment history, quality of life, chronic stress indicators (hair cortisol) and neuropsychological tests (computerized executive function tasks) and are conducted at baseline, end of treatment, and 2 and 4 years post-baseline. Baseline data and treatment data (type, intensity, duration) will be used to predict outcome – persistence of or desistance from SUD. DISCUSSION: There are remarkably few prospective studies worldwide that investigated the course of SUD in adolescents in addiction treatment for longer than 1 year. We are confident that the Youth in Transition study will further our understanding of determinants and consequences of persistent SUD among high-risk adolescents during the critical transition from adolescence to young adulthood. TRIAL REGISTRATION: The Netherlands National Trial Register Trial NL7928. Date of registration January 17, 2019

    A randomized physiotherapy trial in patients with fecal incontinence: design of the PhysioFIT-study

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    <p>Abstract</p> <p>Background</p> <p>Fecal incontinence (FI) is defined as the recurrent involuntary excretion of feces in inappropriate places or at inappropriate times. It is a major and highly embarrassing health care problem which affects about 2 to 24% of the adult population. The prevalence increases with age in both men and women.</p> <p>Physiotherapy interventions are often considered a first-line approach due to its safe and non-invasive nature when dietary and pharmaceutical treatment fails or in addition to this treatment regime. Two physiotherapy interventions, rectal balloon training (RBT) and pelvic floor muscle training (PFMT) are widely used in the management of FI. However, their effectiveness remains uncertain since well-designed trials on the effectiveness of RBT and PFMT versus PFMT alone in FI have never been published.</p> <p>Methods/Design</p> <p>A two-armed randomized controlled clinical trial will be conducted. One hundred and six patients are randomized to receive either PFMT combined with RBT or PFMT alone. Physicians in the University Hospital Maastricht include eligible participants. Inclusion criteria are (1) adults (aged ≥ 18 years), (2) with fecal incontinence complaints due to different etiologies persisting for at least six months, (3) having a Vaizey incontinence score of at least 12, (4) and failure of conservative treatment (including dietary adaptations and pharmacological agents). Baseline measurements consist of the Vaizey incontinence score, medical history, physical examination, medication use, anorectal manometry, rectal capacity measurement, anorectal sensation, anal endosonography, defecography, symptom diary, Fecal Incontinence Quality of Life scale (FIQL) and the PREFAB-score. Follow-up measurements are scheduled at three, six and 12 months after inclusion. Skilled and registered physiotherapists experienced in women's health perform physiotherapy treatment. Twelve sessions are administered during three months according to a standardized protocol.</p> <p>Discussion</p> <p>This section discusses the decision to publish a trial protocol, the actions taken to minimize bias and confounding in the design, explains the choice for two treatment groups, discusses the secondary goals of this study and indicates the impact of this trial on clinical practice.</p> <p>Trial registration</p> <p>The Netherlands Trial Register ISRCTN78640169.</p

    The unusual protoplanetary disk around the T Tauri star ET Cha

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    We present new continuum and line observations, along with modelling, of the faint (6-8) Myr old T Tauri star ET Cha belonging to the eta Chamaeleontis cluster. We have acquired HERSCHEL/PACS photometric fluxes at 70 mic and 160 mic, as well as a detection of the [OI] 63 mic fine-structure line in emission, and derived upper limits for some other far-IR OI, CII, CO and o-H2O lines. The HERSCHEL data is complemented by new ANDICAM B-K photometry, new HST/COS and HST/STIS UV-observations, a non-detection of CO J=3-2 with APEX, re-analysis of a UCLES high-resolution optical spectrum showing forbidden emission lines like [OI] 6300A, [SII] 6731A and 6716A, and [NII] 6583A, and a compilation of existing broad-band photometric data. We used the thermo-chemical disk code ProDiMo and the Monte-Carlo radiative transfer code MCFOST to model the protoplanetary disk around ET Cha. Based on these models we can determine the disk dust mass Mdust = (2.E-8 - 5.E-8) Msun, whereas the total disk gas mass is found to be only little constrained, Mgas = (5.E-5 - 3.E-3) Msun. In the models, the disk extends from 0.022 AU (just outside of the co-rotation radius) to only about 10 AU. Larger disks are found to be inconsistent with the CO J=3-2 non-detection. The low velocity component of the [OI] 6300A emission line is consistent with being emitted from the inner disk. The model can also reproduce the line flux of H2 v=1-0 S(1) at 2.122 mic. An additional high-velocity component of the [OI] 6300A emission line, however, points to the existence of an additional jet/outflow of low velocity (40 - 65) km/s with mass loss rate ~1.E-9 Msun/yr. In relation to our low estimations of the disk mass, such a mass loss rate suggests a disk lifetime of only ~(0.05 - 3) Myr, substantially shorter than the cluster age. The evolutionary state of this unusual protoplanetary disk is discussed.Comment: accepted by Astronomy & Astrophysics (18 pages, 11 figures and 7 tables). Additional 9-page appendix with 6 figures, 3 tables and 37 equation

    Origin of the low-mass electron pair excess in light nucleus-nucleus collisions

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    We report measurements of electron pair production in elementary p+p and d+p reactions at 1.25 GeV/u with the HADES spectrometer. For the first time, the electron pairs were reconstructed for n+p reactions by detecting the proton spectator from the deuteron breakup. We find that the yield of electron pairs with invariant mass Me+e- > 0.15 GeV/c2 is about an order of magnitude larger in n+p reactions as compared to p+p. A comparison to model calculations demonstrates that the production mechanism is not sufficiently described yet. The electron pair spectra measured in C+C reactions are compatible with a superposition of elementary n+p and p+p collisions, leaving little room for additional electron pair sources in such light collision systems.Comment: 11 pages, 2 figures, \usepackage{epsfig
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