58 research outputs found

    D-effects in Toroidally Compactified Type II String Theory

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    We review exact results obtained for R^4 couplings in maximally supersymmetric type II string theories. These couplings offer a privileged scene to understand the rules of semiclassical calculus in string theory. Upon expansion in weak string coupling, they reveal an infinite sum of non-perturbative e^{-1/g} effects that can be imputed to euclidean D-branes wrapped on cycles of the compactification manifolds. They also shed light on the relation between Dp-branes and D-(p-2)branes, D-strings and (p,q) strings, instanton sums and soliton loops. The latter interpretation takes over in D<=6 in order to account for the e^{-1/g^2} effects, still mysterious from the point of view of instanton calculus. [To appear in the proceedings of the conference "Quantum Aspects of Gauge Theories, Supersymmetry and Unification" held at Neuchatel University, Switzerland, 18-23 September 1997.]Comment: 1+6 pages, neuchatel.sty include

    The 0-brane action in a general D=4 supergravity background

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    We begin by presenting the superparticle action in the background of N=2, D=4 supergravity coupled to n vector multiplets interacting via an arbitrary special Kahler geometry. Our construction is based on implementing kappa-supersymmetry. In particular, our result can be interpreted as the source term for N=2 BPS black holes with a finite horizon area. When the vector multiplets can be associated to the complex structure moduli of a Calabi-Yau manifold, then our 0-brane action can be derived by wrapping 3-branes around 3-cycles of the 3-fold. Our result can be extended to the case of higher supersymmetry; we explicitly construct the kappa supersymmetric action for a superparticle moving in an arbitrary N=8 supergravity background with 1/2, 1/4 or 1/8 residual supersymmetry.Comment: 29 pages, LaTex; v2 and v3: twice reference added and typos corrected; v4: typos corrected for final version in Class.Quantum Gra

    The rigid limit in Special Kahler geometry; From K3-fibrations to Special Riemann surfaces: a detailed case study

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    The limiting procedure of special Kahler manifolds to their rigid limit is studied for moduli spaces of Calabi-Yau manifolds in the neighbourhood of certain singularities. In two examples we consider all the periods in and around the rigid limit, identifying the nontrivial ones in the limit as periods of a meromorphic form on the relevant Riemann surfaces. We show how the Kahler potential of the special Kahler manifold reduces to that of a rigid special Kahler manifold. We extensively make use of the structure of these Calabi-Yau manifolds as K3 fibrations, which is useful to obtain the periods even before the K3 degenerates to an ALE manifold in the limit. We study various methods to calculate the periods and their properties. The development of these methods is an important step to obtain exact results from supergravity on Calabi-Yau manifolds.Comment: 79 pages, 8 figures. LaTeX; typos corrected, version to appear in Classical and Quantum Gravit

    Laying the foundations for gene therapy in Italy for patients with haemophilia A: A Delphi consensus study

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    IntroductionCurrent treatment for haemophilia A involves factor VIII replacement or non-replacement (emicizumab) therapies, neither of which permanently normalise factor VIII levels. Gene therapy using adeno-associated viral (AAV) vectors is an emerging long-term treatment strategy for people with severe haemophilia A (PwSHA) that is likely to be available for clinical use in the near future. AimThis article proposes practical guidelines for the assessment, treatment, and follow-up of potential PwSHA candidates for AAV-based gene therapy. MethodUsing the Delphi method, a working group of Italian stakeholders with expertise in and knowledge of the care of adults with haemophilia A analysed literature for AAV-based gene therapy and drafted a list of statements that were circulated to a panel of Italian peers. During two rounds of voting, panel members voted on their agreement with each statement to reach a consensus. ResultsThe Delphi process yielded 40 statements regarding haemophilia A gene therapy, across five topics: (1) organisational model; (2) multidisciplinary team; (3) patient engagement; (4) laboratory surveillance; and (5) patient follow-up and gene therapy outcomes. The consensus was reached for all 40 statements, with the second round of voting needed for five statements. ConclusionUse of the hub-and-spoke organisational model and multidisciplinary teams are expected to optimise patient selection for gene therapy, as well as the management of dosing and patient follow-up, patient engagement, laboratory surveillance, and patient expectations regarding outcomes. This approach should allow the benefits of AAV-based gene therapy for haemophilia A to be maximised

    Oral ondansetron versus domperidone for symptomatic treatment of vomiting during acute gastroenteritis in children: multicentre randomized controlled trial

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    <p>Abstract</p> <p>Background</p> <p>Vomiting in children with acute gastroenteritis (AG) is not only a direct cause of fluid loss but it is also a major factor of failure of oral rehydration therapy (ORT). Physicians who provide care to paediatric patients in the emergency department (ED) usually prescribe intravenous fluid therapy (IVT) for mild or moderate dehydration when vomiting is the major symptom. Thus, effective symptomatic treatment of vomiting would lead to an important reduction in the use of IVT and, consequently, of the duration of hospital stay and of frequency of hospital admission. Available evidence on symptomatic treatment of vomiting shows the efficacy of the most recently registered molecule (ondansetron) but a proper evaluation of antiemetics drugs largely used in clinical practice, such as domperidone, is lacking.</p> <p>Objectives</p> <p>To compare the efficacy of ondansetron and domperidone for the symptomatic treatment of vomiting in children with AG who have failed ORT.</p> <p>Methods/Design</p> <p>Multicentre, double-blind randomized controlled trial conducted in paediatric EDs. Children aged from 1 to 6 years who vomiting, with a presumptive clinical diagnosis of AG, and without severe dehydration will be included. After the failure of a initial ORS administration in ED, eligible children will be randomized to receive: 1) ondansetron syrup (0,15 mg/Kg of body weight); 2) domperidone syrup (0,5 mg/Kg of body weight); 3) placebo. The main study outcome will be the percentage of patients needing nasogastric or IVT after symptomatic oral treatment failure, defined as vomiting or fluid refusal after a second attempt of ORT. Data relative to study outcomes will be collected at 30 minute intervals for a minimum of 6 hours. A telephone follow up call will be made 48 hours after discharge. A total number of 540 children (i.e. 180 patients in each arm) will be enrolled.</p> <p>Discussion</p> <p>The trial results would provide evidence on the efficacy of domperidone, which is largely used in clinical practice despite the lack of proper evaluation and a controversial safety profile, as compared to ondansetron, which is not yet authorized in Italy despite evidence supporting its efficacy in treating vomiting. The trial results would contribute to a reduction in the use of IVT and, consequently, in hospital admissions in children with AG. The design of this RCT, which closely reflect current clinical practice in EDs, will allow immediate transferability of results.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01257672">NCT01257672</a></p

    Association of kidney disease measures with risk of renal function worsening in patients with type 1 diabetes

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    Background: Albuminuria has been classically considered a marker of kidney damage progression in diabetic patients and it is routinely assessed to monitor kidney function. However, the role of a mild GFR reduction on the development of stage 653 CKD has been less explored in type 1 diabetes mellitus (T1DM) patients. Aim of the present study was to evaluate the prognostic role of kidney disease measures, namely albuminuria and reduced GFR, on the development of stage 653 CKD in a large cohort of patients affected by T1DM. Methods: A total of 4284 patients affected by T1DM followed-up at 76 diabetes centers participating to the Italian Association of Clinical Diabetologists (Associazione Medici Diabetologi, AMD) initiative constitutes the study population. Urinary albumin excretion (ACR) and estimated GFR (eGFR) were retrieved and analyzed. The incidence of stage 653 CKD (eGFR &lt; 60 mL/min/1.73 m2) or eGFR reduction &gt; 30% from baseline was evaluated. Results: The mean estimated GFR was 98 \ub1 17 mL/min/1.73m2 and the proportion of patients with albuminuria was 15.3% (n = 654) at baseline. About 8% (n = 337) of patients developed one of the two renal endpoints during the 4-year follow-up period. Age, albuminuria (micro or macro) and baseline eGFR &lt; 90 ml/min/m2 were independent risk factors for stage 653 CKD and renal function worsening. When compared to patients with eGFR &gt; 90 ml/min/1.73m2 and normoalbuminuria, those with albuminuria at baseline had a 1.69 greater risk of reaching stage 3 CKD, while patients with mild eGFR reduction (i.e. eGFR between 90 and 60 mL/min/1.73 m2) show a 3.81 greater risk that rose to 8.24 for those patients with albuminuria and mild eGFR reduction at baseline. Conclusions: Albuminuria and eGFR reduction represent independent risk factors for incident stage 653 CKD in T1DM patients. The simultaneous occurrence of reduced eGFR and albuminuria have a synergistic effect on renal function worsening

    Oral ondansetron versus domperidone for acute gastroenteritis in pediatric emergency departments: Multicenter double blind randomized controlled trial

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    The use of antiemetics for vomiting in acute gastroenteritis in children is still a matter of debate. We conducted a double-blind randomized trial to evaluate whether a single oral dose of ondansetron vs domperidone or placebo improves outcomes in children with gastroenteritis. After failure of initial oral rehydration administration, children aged 1-6 years admitted for gastroenteritis to the pediatric emergency departments of 15 hospitals in Italy were randomized to receive one oral dose of ondansetron (0.15 mg/kg) or domperidone (0.5 mg/kg) or placebo. The primary outcome was the percentage of children receiving nasogastric or intravenous rehydration. A p value of 0.014 was used to indicate statistical significance (and 98.6% CI were calculated) as a result of having carried out two interim analyses. 1,313 children were eligible for the first attempt with oral rehydration solution, which was successful for 832 (63.4%); 356 underwent randomization (the parents of 125 children did not give consent): 118 to placebo, 119 to domperidone, and 119 to ondansetron. Fourteen (11.8%) needed intravenous rehydration in the ondansetron group vs 30 (25.2%) and 34 (28.8%) in the domperidone and placebo groups, respectively. Ondansetron reduced the risk of intravenous rehydration by over 50%, both vs placebo (RR 0.41, 98.6% CI 0.20-0.83) and domperidone (RR 0.47, 98.6% CI 0.23-0.97). No differences for adverse events were seen among groups. In a context of emergency care, 6 out of 10 children aged 1-6 years with vomiting due to gastroenteritis and without severe dehydration can be managed effectively with administration of oral rehydration solution alone. In children who fail oral rehydration, a single oral dose of ondansetron reduces the need for intravenous rehydration and the percentage of children who continue to vomit, thereby facilitating the success of oral rehydration. Domperidone was not effective for the symptomatic treatment of vomiting during acute gastroenteritis
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