1,102 research outputs found

    Structure of cccˉcˉcc \bar c \bar c tetraquarks and interpretation of LHC states

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    Motivated by recent experimental evidence for apparent cccˉcˉcc\bar c \bar c states at LHCb, CMS and ATLAS, we consider how the mass spectrum and decays of such states can be used to discriminate among their possible theoretical interpretations, with a particular focus on identifying whether quarks or diquarks are the most relevant degrees of freedom. Our preferred scenario is that X(6600)X(6600) and its apparent partner state X(6400)X(6400) are the tensor (2++)(2^{++}) and scalar (0++)(0^{++}) states of an S-wave multiplet of cccˉcˉcc\bar c \bar c states. Using tetraquark mass relations which are independent of (or only weakly dependent on) model parameters, we give predictions for the masses of additional partner states with axial and scalar quantum numbers. Additionally, we give predictions for relations among decay branching fractions to J/ψJ/ψJ/\psi J/\psi, J/ψηcJ/\psi \eta_c, ηcηc\eta_c\eta_c and D()Dˉ()D^{(*)} \bar{D}^{(*)} channels. The scenario we consider is consistent with existing experimental data on J/ψJ/ψJ/\psi J/\psi, and our predictions for partner states and their decays can be confronted with future experimental data, to discriminate between quark and diquark models

    Tetraquark mass relations in quark and diquark models

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    We present new linear relations among the masses of S-wave tetraquarks with either one flavour (QQQˉQˉQQ \bar Q \bar Q) or two (QQqˉqˉQQ\bar q \bar q). Because the relations are sensitive to the hidden-colour, spin, and spatial degrees of freedom, comparison to experimental data can help to reveal the internal structure of tetraquarks, and discriminate among different theoretical models. Depending on the model, the relations are either exact, or valid in perturbation theory, and a thorough comparison with existing literature confirms their validity at the MeV level. Additionally, we explore the connections among tetraquark models, and show how those with effective (quark or diquark) masses are related to dynamical potential models. We also show how the spectrum of diquark models is effectively a limiting case of (more general) quark models, and in particular, that the diquark concept is most relevant in the particular combination QQqˉqˉQQ\bar q \bar q, where QQ is much heavier than qˉ\bar q.Comment: Published versio

    Intranasal Inhalation of Oxytocin Improves Face Processing in Developmental Prosopagnosia

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    Developmental prosopagnosia (DP) is characterised by a severe, lifelong impairment in face recognition. Little work has attempted to improve face processing in these individuals, but intriguingly, recent evidence suggests oxytocin can improve face processing in both healthy participants and individuals with autism. This study examined whether oxytocin could also improve face processing in individuals with DP. Ten adults with the condition and 10 matched controls were tested using a randomized placebo-controlled double-blind within-subject experimental design (AB-BA). Each participant took part in two testing sessions where they inhaled 24IU of oxytocin or placebo spray and completed two face processing tests: one assessing face memory and the other face perception. Results showed main effects of both participant group and treatment condition in both face processing tests, but the two did not interact. Specifically, the performance of DP participants was significantly lower than control performance under both oxytocin and placebo conditions, but oxytocin improved processing to a similar extent in both groups

    Heat Treatment of Friction-Stir-Welded 7050 Aluminum Plates

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    A method of heat treatment has been developed to reverse some of the deleterious effects of friction stir welding of plates of aluminum alloy 7050. This alloy is considered unweldable by arc and high-energy-density beam fusion welding processes. The alloy can be friction stir welded, but as-welded workpieces exhibit low ductility, low tensile and yield strengths, and low resistance to stress corrosion cracking. Heat treatment according to the present method increases tensile and yield strengths, and minimizes or eliminates stress corrosion cracking. It also increases ductility. This method of heat treatment is a superior alternative to a specification-required heat treatment that caused the formation of large columnar grains, which are undesired. Workpieces subjected to the prior heat treatment exhibited elongations <2 percent, and standard three-point bend specimens shattered. The development of the present heat treatment method was guided partly by the principles that (1) by minimizing grain sizes and relieving deformation stresses, one can minimize or eliminate stress corrosion cracking and (2) the key to maximizing strength and eliminating residual stresses is to perform post-weld solution heating for as long a time as possible while incurring little or no development of large columnar grains in friction stir weld nuggets. It is necessary to perform some of the solution heat treatment (to soften the alloy and improve machine welding parameters) before welding. The following is an example of thickness- dependent pre- and post-weld heat treatments according to the present method: For plates 0.270 in. (approx.6.86 mm) thick milled from plates 4.5 in. (114.3 mm) thick, perform pre-weld solution heating at 890 F (477 C) for 1 hour, then cool in air. After friction stir welding, perform solution heating for 10 minutes, quench, hold at room temperature for 96 hours, then age at 250 F (121 C) for 5 hours followed by 325 F (163 C) for 27 hours

    On the dynamics and composition of the high-latitude thermosphere

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    Recent experimental measurements of the dynamics of the neutral upper thermosphere have demonstrated the important roles of ion-drag and Joule heating processes in establishing the basic neutral wind morphology and controlling neutral composition, particularly in the high-latitude region. Instruments on the Dynamics Explorer-2 spacecraft (DE 2), for example, were capable of measuring the three-dimensional vector neutral wind and ion drift in the thermosphere along the orbital track, together with constituent densities and temperatures. Ground-based optical and radar measurements of winds and temperatures from observatories in Greenland have contributed additional measurements of thermospheric neutral wind velocities and ionospheric parameters. The comprehensive nature of these various data sets has enabled more stringent experimental constraints to be placed on the numerical models of the region (thermosphere-ionosphere general circulation models, TIGCMs), leading to an improved theoretical understanding of the important physical processes that control thermospheric circulation and variability. In addition, the measurements have enabled the development of semi-empirical models of thermosphere dynamics which can be used in various theoretical studies. The Vector Spherical Harmonic (VSH) model, for example, provides a description of global thermospheric state variables (wind, temperature and density), using a combination of empirical data and NCAR-TIGCM calculations. This paper presents a brief review of some of the more recent progress made in this area by the team of researchers at the University of Michigan, with emphasis on the interpretation of experimental measurements made from DE 2 and from ground-based observatories in Thule and Sondrestromfjord, Greenland. Comparisons between individual data sets from these sources and the VSH model are also presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29167/1/0000212.pd

    A phase 1 study evaluating rovalpituzumab tesirine in frontline treatment of patients with extensive-stage SCLC

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    INTRODUCTION: Rovalpituzumab tesirine (Rova-T) is an antibody-drug conjugate targeting DLL3, a Notch pathway ligand highly expressed on SCLC cells. Rova-T was evaluated alone or in combination with platinum-based chemotherapy (cisplatin or carboplatin combined with etoposide [CE]) in frontline treatment of extensive-stage SCLC. METHODS: One cycle of CE pre-enrollment was permitted (later mandated). The following four cohorts were enrolled: Rova-T monotherapy (0.3 mg/kg, every 6 [q6] wk × 2; cohort 1; n = 4); Rova-T induction (0.3 mg/kg, q6 wk × 2) followed by CE every 21 days (q21) × 4 (cohort 2; n = 5); Rova-T (0.1 or 0.2 mg/kg, q6 wk × 2) overlapping with CE q21 × 4 (cohort 3; n = 14); and Rova-T maintenance (0.3 mg/kg, q6 wk × 2) after CE q21 × 4 (cohort 4; n = 3). RESULTS: A total of 26 patients were dosed (cohort 3: 14; cohorts 1, 2, and 4 combined: 12). Median age was 66 years, and 73% had Eastern Cooperative Oncology Group performance status of 1. In cohort 3, seven patients (50%) had confirmed objective responses, with a median progression-free survival of 5.2 months and median overall survival of 10.3 months. Compared with cohorts 1, 2, and 4 combined, cohort 3 had lower frequency of some Rova-T-related adverse events of special interest, such as pleural effusion (0 versus 33%), pericardial effusion (0 versus 17%), ascites (0 versus 8%), peripheral edema (36% versus 42%), generalized edema (0 versus 8%), pneumonia (7% versus 25%), and hypoalbuminemia (0 versus 17%). CONCLUSIONS: Lower Rova-T doses may be associated with lower incidence of some Rova-T-related adverse events of special interest. Rova-T 0.2 mg/kg plus CE (cohort 3) was tolerable; however, there was no clear efficacy benefit of adding Rova-T to CE

    Participant Blinding and Gastrointestinal Illness in a Randomized, Controlled Trial of an In-Home Drinking Water Intervention

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    We conducted a randomized, triple-blinded home drinking water intervention trial to determine if a large study could be undertaken while successfully blinding participants. Households were randomized 50:50 to use externally identical active or sham treatment devices. We measured the effectiveness of blinding of participants by using a published blinding index in which values >0.5 indicate successful blinding. The principal health outcome measured was “highly credible gastrointestinal illness” (HCGI). Participants (n=236) from 77 households were successfully blinded to their treatment assignment. At the end of the study, the blinding index was 0.64 (95% confidence interval 0.51-0.78). There were 103 episodes of HCGI during 10,790 person-days at risk in the sham group and 82 episodes during 11,380 person-days at risk in the active treatment group. The incidence rate ratio of disease (adjusted for the clustered sampling) was 1.32 (95% CI 0.75, 2.33) and the attributable risk was 0.24 (95% CI -0.33, 0.57). These data confirm that participants can be successfully blinded to treatment group assignment during a randomized trial of an in-home drinking water intervention

    A Randomized, Controlled Trial of In-Home Drinking Water Intervention to Reduce Gastrointestinal Illness

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    Trials have provided conflicting estimates of the risk of gastrointestinal illness attributable to tap water. To estimate this risk in an Iowa community with a well-run water utility with microbiologically challenged source water, the authors of this 2000-2002 study randomly assigned blinded volunteers to use externally identical devices (active device: 227 households with 646 persons; sham device: 229 households with 650 persons) for 6 months (cycle A). Each group then switched to the opposite device for 6 months (cycle B). The active device contained a 1-microm absolute ceramic filter and used ultraviolet light. Episodes of highly credible gastrointestinal illness, a published measure of diarrhea, nausea, vomiting, and abdominal cramps, were recorded. Water usage was recorded with personal diaries and an electronic totalizer. The numbers of episodes in cycle A among the active and sham device groups were 707 and 672, respectively; in cycle B, the numbers of episodes were 516 and 476, respectively. In a log-linear generalized estimating equations model using intention-to-treat analysis, the relative rate of highly credible gastrointestinal illness (sham vs. active) for the entire trial was 0.98 (95% confidence interval: 0.86, 1.10). No reduction in gastrointestinal illness was detected after in-home use of a device designed to be highly effective in removing microorganisms from water

    Modelling of composition changes during F-region storms: a reassessment

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    A recalculation of the global changes of thermospheric gas composition, resulting from strong heat inputs in the auroral ovals, shows that (contrary to some previous suggestions) widespread increases of mean molecular mass are produced at mid-latitudes, in summer and at equinox. Decreases of mean molecular mass occur at mid-latitudes in winter. Similar results are given by both the `UCL' and `NCAR TIGCM' three-dimensional models. The computed composition changes now seem consistent with the local time and seasonal response observed by satellites, and can broadly account for `negative storm effects' in the ionospheric F2-layer at mid-latitudes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29311/1/0000375.pd

    Predictors of rapid aortic root dilation and referral for aortic surgery in Marfan syndrome

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    Few data exist regarding predictors of rapid aortic root dilation and referral for aortic surgery in Marfan syndrome (MFS). To identify independent predictors of the rate of aortic root (AoR) dilation and referral for aortic surgery, we investigated the data from the Pediatric Heart Network randomized trial of atenolol versus losartan in young patients with MFS. Data were analyzed from the echocardiograms at 0, 12, 24, and 36months read in the core laboratory of 608 trial subjects, aged 6months to 25 years, who met original Ghent criteria and had an AoR z-score (AoRz)>3. Repeated measures linear and logistic regressions were used to determine multivariable predictors of AoR dilation. Receiver operator characteristic curves were used to determine cut-points in AoR dilation predicting referral for aortic surgery. Multivariable analysis showed rapid AoR dilation as defined by change in AoRz/year>90th percentile was associated with older age, higher sinotubular junction z-score, and atenolol use (R-2=0.01) or by change in AoR diameter (AoRd)/year>90th percentile with higher sinotubular junction z-score and non-white race (R-2=0.02). Referral for aortic root surgery was associated with higher AoRd, higher ascending aorta z-score, and higher sinotubular junction diameter:ascending aorta diameter ratio (R-2=0.17). Change in AoRz of 0.72 SD units/year had 42% sensitivity and 92% specificity and change in AoRd of 0.34cm/year had 38% sensitivity and 95% specificity for predicting referral for aortic surgery. In this cohort of young patients with MFS, no new robust predictors of rapid AoR dilation or referral for aortic root surgery were identified. Further investigation may determine whether generalized proximal aortic dilation and effacement of the sinotubular junction will allow for better risk stratification. Rate of AoR dilation cut-points had high specificity, but low sensitivity for predicting referral for aortic surgery, limiting their clinical use. Clinical Trial Number ClinicalTrials.gov number, NCT00429364
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