253 research outputs found

    A probabilistic approach to stormwater runoff control through permeable pavements beneath urban trees

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    : One of the most current and urgent challenges is making cities sustainable and resilient to climate change. From this perspective, Nature-Based Solutions (NBSs) are well-recognized strategies for stormwater control and water cycle restoration. Urban trees are an example of NBS. However, the high degree of soil sealing typically found in urban environments limits natural processes such as infiltration and hinders the water and nutrient supply for proper root development, which weakens tree stability. Permeable pavements at the base of urban trees, on the one hand, facilitate infiltration, which helps runoff control, and on the other hand, improve stormwater retention and soil humidity, which enhance root feeding. This paper proposes an analytical-probabilistic approach to estimate the contribution of permeable pavements to stormwater management. The equations developed in this study relate the runoff probability to the storage volume, the infiltration rate into the underlying soil, and the average values of the hydrological variables in the input. The model allows us to select different runoff thresholds and considers the possibility that residual volume from previous rainfall events prefills the storage capacity. An application to a case study in Sao Paulo (Brazil) has been presented. It investigates the influence of the different parameters used in the model on the results. The comparison of the outcomes obtained using the developed equations with those obtained from the continuous simulation of measured data confirmed the effectiveness of the proposed analytical-probabilistic approach and the suitability of using permeable pavements at the base of urban trees for improving stormwater retention

    A first look at maximally twisted mass lattice QCD calculations at the physical point

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    In this contribution, a first look at simulations using maximally twisted mass Wilson fermions at the physical point is presented. A lattice action including clover and twisted mass terms is presented and the Monte Carlo histories of one run with two mass-degenerate flavours at a single lattice spacing are shown. Measurements from the light and heavy-light pseudoscalar sectors are compared to previous Nf=2N_f = 2 results and their phenomenological values. Finally, the strategy for extending simulations to Nf=2+1+1N_f = 2 + 1 + 1 is outlined.Comment: presented at the 31st International Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz, German

    Theoretical evidences for enhanced superconducting transition temperature of CaSi2_2 in a high-pressure AlB2_2 phase

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    By means of first-principles calculations, we studied stable lattice structures and estimated superconducting transition temperature of CaSi2_2 at high pressure. Our simulation showed stability of the AlB2_2 structure in a pressure range above 17 GPa. In this structure, doubly degenerated optical phonon modes, in which the neighboring silicon atoms oscillate alternately in a silicon plane, show prominently strong interaction with the conduction electrons. In addition there exists a softened optical mode (out-of-plan motion of silicon atoms), whose strength of the electron-phonon interaction is nearly the same as the above mode. The density of states at the Fermi level in the AlB2_2 structure is higher than that in the trigonal structure. These findings and the estimation of the transition temperature strongly suggest that higher TcT_{\rm c} is expected in the AlB2_2 structure than the trigonal structures which are known so far.Comment: 6 pages and 11 figure

    Ratio of kaon and pion leptonic decay constants with Nf=2+1+1N_f = 2 + 1 + 1 Wilson-clover twisted-mass fermions

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    We present a determination of the ratio of kaon and pion leptonic decay constants in isosymmetric QCD (isoQCD), fK/fπf_K / f_\pi, making use of the gauge ensembles produced by the Extended Twisted Mass Collaboration (ETMC) with Nf=2+1+1N_f = 2 + 1 + 1 flavors of Wilson-clover twisted-mass quarks, including configurations close to the physical point for all dynamical flavors. The simulations are carried out at three values of the lattice spacing ranging from 0.068\sim 0.068 to 0.092\sim 0.092 fm with linear lattice size up to L5.5L \sim 5.5~fm. The scale is set by the PDG value of the pion decay constant, fπisoQCD=130.4 (2)f_\pi^{isoQCD} = 130.4~(2) MeV, at the isoQCD pion point, MπisoQCD=135.0 (2)M_\pi^{isoQCD} = 135.0~(2) MeV, obtaining for the gradient-flow (GF) scales the values w0=0.17383 (63)w_0 = 0.17383~(63) fm, t0=0.14436 (61)\sqrt{t_0} = 0.14436~(61) fm and t0/w0=0.11969 (62)t_0 / w_0 = 0.11969~(62) fm. The data are analyzed within the framework of SU(2) Chiral Perturbation Theory (ChPT) without resorting to the use of renormalized quark masses. At the isoQCD kaon point MKisoQCD=494.2 (4)M_K^{isoQCD} = 494.2~(4) MeV we get (fK/fπ)isoQCD=1.1995 (44)(f_K / f_\pi)^{isoQCD} = 1.1995~(44), where the error includes both statistical and systematic uncertainties. Implications for the Cabibbo-Kobayashi-Maskawa (CKM) matrix element Vus|V_{us}| and for the first-row CKM unitarity are discussed.Comment: 68 pages, 14 figures, 12 tables. Version to appear in PR

    Hip viscosupplementation under ultra-sound guidance riduces NSAID consumption in symptomatic hip osteoarthritis patients in a long follow-up. Data from Italian registry.

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    Introduction: Non-steroidal anti-inflammatory drugs (NSAIDs) consumption is strictly related to a high gastrointestinal and cardiovascular mortality and morbidity rate. Osteoarthritis Research Society International (OARSI) recommendations in patients with symptomatic hip or knee OA stated that NSAIDs should be used at the lowest effective dose but their long-term use should be avoided if possible. OARSI guidelines for the treatment of the hip OA include the use of viscosupplementation, which aims to restore physiological and Theological features of the synovial fluid. Objective: Aim of this multicentric, open and retrospective study is to investigate if NSAID consumption may be reduced by the use of ultrasound-guided intra-articular injection of several hyaluronic acid (HA) products in hip joint administered in patients affected by symptomatic hip OA. Materials and Methods: Patients affected by mono or bilateral symptomatic hip OA according to American Rheumatology Association (ARA) criteria, radiological OA graded II-IV (Kellgren and Lawrence) entered the study and were administered with ultrasound-guided intra-articular injection of hyaluronic acid products. As a primary endpoint, consumption of NSAIDs was evaluated by recording the number of days a month (range 0-30) the patient had used NSAID during the previous month, reported at each visit during the 24 months follow-up period. Secondary endpoints included further analysis for subgroups of patients categorized for Lequesne index score, Kellgren-Lawrence score, pain visual analogue scale (VAS) score, ultrasound pattern, age, hyaluronic acid used. Results: 2343 patients entered the study. Regarding primary endpoint, the consumption of NSAIDs was reduced of 48.2% at the third month when compared with baseline values. This sparing effect increased at 12th and 24th month with a reduction respectively of 50% and 61% in comparison to baseline values. These differences were statistically significant. Conclusions: These data point out that intraarticular hyaluronan preparations provide OA pain relief and reduce NSAIDs consumption in a large cohort of patients for a long period of follow-up. Multiple courses of viscosupplementation (vs) are required to maintain low dose of NSAID consumption over time. NSAIDs consumption is strictly related to an high gastrointestinal and cardiovascular mortality and morbidity rate, instead HA intra-articular treatment is well tolerated and is associated with a low incidence of adverse effects. For these reasons further studies evaluating cost-effectiveness and cost-utility of VS in the management of hip OA are required

    Matrix metalloproteinases and their tissue inhibitors after selective laser trabeculoplasty in pseudoexfoliative secondary glaucoma

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    <p>Abstract</p> <p>Background</p> <p>The aim of this study was to assess changes in metalloproteinases (MMP-2) and tissue inhibitor of metalloproteinases (TIMP-2) following selective laser trabeculoplasty (SLT) in patients with pseudoexfoliative glaucoma (PEXG).</p> <p>Methods</p> <p>We enrolled 15 patients with PEXG and cataracts (PEXG-C group) and good intraocular pressure (IOP) controlled with β-blockers and dorzolamide eye drops who were treated by cataract phacoemulsification and 15 patients with pseudoexfoliative glaucoma (PEXG-SLT group). The PEXG-SLT patients underwent a trabeculectomy for uncontrolled IOP in the eye that showed increased IOP despite the maximum drug treatment with β-blockers and dorzolamide eye drops and after ineffective selective laser trabeculoplasty (SLT). The control group consisted of 15 subjects with cataracts. Aqueous humor was aspirated during surgery from patients with PEXG-C, PEXG-SLT and from matched control patients with cataracts during cataract surgery or trabeculectomy. The concentrations of MMP-2 and TIMP-2 in the aqueous humor were assessed with commercially available ELISA kits.</p> <p>Results</p> <p>In PEXG-SLT group in the first 10 days after SLT treatment a significant reduction in IOP was observed: 25.8 ± 1.9 vs 18.1.0 ± 1.4 mm/Hg (p < 0.001), but after a mean time of 31.5 ± 7.6 days IOP increased and returned to pretreatment levels: 25.4 ± 1.6 mm/Hg (p < 0.591). Therefore a trabeculectomy was considered necessary.</p> <p>The MMP-2 in PEXG-C was 57.77 ± 9.25 μg/ml and in PEXG-SLT was 58.52 ± 9.66 μg/ml (p < 0.066). TIMP-2 was 105.19 ± 28.53 μg/ml in PEXG-C and 105.96 ± 27.65 μg/ml in PEXG-SLT (p < 0.202). The MMP-2/TIMP-2 ratio in the normal subjects was 1.11 ± 0.44. This ratio increase to 1.88 ± 0.65 in PEXG-C (p < 0.001) and to 1.87 ± 0.64 in PEXG-SLT (p < 0.001). There was no statistically significant difference between the PEXG-C and PEXG-SLT ratios (p < 0.671).</p> <p>Conclusion</p> <p>This case series suggest that IOP elevation after SLT can be a serious adverse event in some PEXG patients. The IOP increase in these cases would be correlated to the failure to decrease the TIMP-2/MMP-2 ratio.</p> <p>Trial registration</p> <p>Current Controlled Trials <b>ISRCTN79745214</b></p
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