50 research outputs found

    A unified steady and unsteady formulation for hydrodynamic potential flow simulations with fully nonlinear free surface boundary conditions

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    This work discusses the correct modeling of the fully nonlinear free surface boundary conditions to be prescribed in water waves flow simulations based on potential flow theory. The main goal of such a discussion is that of identifying a mathematical formulation and a numerical treatment that can be used both to carry out transient simulations, and to compute steady solutions -- for any flow admitting them. In the literature on numerical towing tank in fact, steady and unsteady fully nonlinear potential flow solvers are characterized by different mathematical formulations. The kinematic and dynamic fully nonlinear free surface boundary conditions are discussed, and in particular it is proven that the kinematic free surface boundary condition, written in semi-Lagrangian form, can be manipulated to derive an alternative non penetration boundary condition by all means identical to the one used on the surface of floating bodies or on the basin bottom. The simplified mathematical problem obtained is discretized over space and time via Boundary Element Method (BEM) and Implicit Backward Difference Formula (BDF) scheme, respectively. The results confirm that the solver implemented is able to solve steady potential flow problems just by eliminating null time derivatives in the unsteady formulation. Numerical results obtained confirm that the solver implemented is able to accurately reproduce results of classical steady flow solvers available in the literature.Comment: The final version of the present paper has been accepted for publication on Applied Mathematical Modellin

    One-Handed Rotational Phacoemulsification Technique

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    Introduction: We described a one-handed rotational phacoemulsification technique to decrease phaco time and power, and surgical stress on the cornea in eyes with different types of cataract. Methods: In this technique a single sutureless corneal incision was made without any side-port incision. After hydrodissection and hydrodelamination were performed, a phaco tip was positioned in contact with the nucleus beside the capsulorhexis edge. By using a peristaltic pump, phacoemulsification was started with high levels of vacuum to keep the probe tip on the edge of the lens and to ensure the rotation of the nucleus, and with low ultrasound energy. The torsional mode used required less occlusion time and volume of fluid. The inclination of the tip was modified to 45-degree, directing it toward the lens center. So the nucleus was aspirated from the periphery toward the center by a rotational movement. Results: The eye in the technical video had a NC4-NO4 cataract. The preoperative vision in this eye was 20/100 with no improvement with refraction. On postoperative day 1, visual acuity had improved to 20/20. We recorded low intraoperative parameters including ultrasound time (21.4 sec), phacoemulsification power (73%), balanced salt solution used (31 mL) and cumulative dissipated energy (7.27) at the conclusion of the case. After 1 month, Central Corneal Thickness changed from 504 µm to 516 µm, and Endothelial Cell Loss was 1.15%. Conclusion: This technique uses a single clear corneal incision, high vacuum and low ultrasound power to reduce the exposition to excessive surgical maneuvers, fluid turbulence and ultrasound energy

    Immune system alterations in lung cancer patients.

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    The immune system plays an important role in the defense against neoplastic disease and immune responses show temporal changes related to circadian variations of antibodies, total lymphocytes in the peripheral blood and cell mediated immune responses. In this study we evaluate, lymphocyte subpopulations and interleukin-2 (IL-2) serum levels in peripheral blood samples collected at four-hour intervals for 24-hours starting at 06.00h from ten healthy subjects aged 65–79 years (mean age ± S.E. 67.28 ±3.11) and from ten subjects suffering from untreated non small cell lung cancer aged 65–78 years (mean age ± S.E. 68.57 ± 1.81). Areas under the curve, mean diurnal levels (mean of 06.00–10.00–14.00 h) and mean nocturnal levels (mean of 18.00–22.00–02.00 h) were calculated, and the presence of circadian rhythmicity was evaluate. When we compared AUC values there was a decrease in CD8bright (T suppressor subset) and an increase in CD16 (natural killer cells) and of IL-2 serum levels in cancer patients. When we compared mean diurnal levels, CD8 (T suppressor/cytotoxic subset) and CD8bright levels were lower, and CD16 levels were higher in cancer patients. When we compared mean nocturnal levels, CD16 and CD25 (T and B activated lymphocytes with expression of the a chain of IL-2 receptor) levels were higher, while CD8, CD8bright, CD20 (total B-cells), TcRd1 (epitope of the constant domain of d chain of T-cell receptor 1) and dTcS1 (epitope of the variable domain of d chain of T-cell receptor1) levels were lower in cancer patients. A clear circadian rhythm was validated for the time-qualified changes in CD4, CD20, HLA-DR with acrophase at night, and CD8, CD8bright, CD8dim, CD16, TcRd1 and dTcS1 with acrophase in the morning in the control group. A clear circadian rhythm was validated for the time-qualified changes in CD4 with acrophase at night, in the group of cancer patients. Results obtained in our study show that lung cancer is associated with anomalies of proportion and circadian variations of lymphocyte subsets that must be considered when adoptive immunotherapy has to be planned

    Chronobiologic study of the GH-IGF1 axis and the ageing immune system

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    One of the many systems that weakens as we age is our immune system and there is a reduction in the GH-IGF1 axis activity with increasing age. In this study we evaluated the immune system and the GH-IGF1 axis function in healthy ageing. CD3, CD4, CD20, CD25, HLA-DR and GH showed acrophase during the night, whereas CD8, CD16 and TCRγδ expressing cells showed acrophase during the day. MESOR of CD3 was higher in the old aged subjects, MESOR of CD20 and CD20 values at 14:00h and at 02:00h were higher in the young middle aged subjects, MESOR of CD25 and CD25 values at 10:00 were higher in the elderly subjects, MESOR of HLA-DR was higher in the young middle aged subjects, whereas MESOR of DR+T cells and HLA-DR at 02:00h were higher in the elderly subjects, MESOR of TCRγδ bearing cells was higher in the elderly subjects, GH value at 18:00h was also higher in the elderly subjects, and MESOR of IGF1 was higher in the young middle aged subjects. There was a statistically significant difference for the acrophases of CD25, HLA-DR and IGF1. There were different and opposing correlations among lymphocyte subpopulations and GH-IGF1 axis hormones in young and middle aged subjects in comparison with old aged subjects. Linear regression evidenced a statistically significant positive trend between age and the 24h mean of CD3 and CD25 and a statistically significant negative trend between age and the 24h mean of CD20 and GH. In conclusion, ageing is associated with an altered GH and IGF1 secretion, with decreased peripheral B cell compartment, increased peripheral T cell compartment and alterations of circadian rhythmicity

    Association of Neuroretinal Thinning and Microvascular Changes with Hypertension in an Older Population in Southern Italy.

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    Retinal microvasculature assessment at capillary level may potentially aid the evaluation of early microvascular changes due to hypertension. We aimed to investigate associations between the measures obtained using optical coherence tomography (OCT) and OCT-angiography (OCT-A) and hypertension, in a southern Italian older population. We performed a cross-sectional analysis from a population-based study on 731 participants aged 65 years+ subdivided into two groups according to the presence or absence of blood hypertension without hypertensive retinopathy. The average thickness of the ganglion cell complex (GCC) and the retinal nerve fiber layer (RNFL) were measured. The foveal avascular zone area, vascular density (VD) at the macular site and of the optic nerve head (ONH) and radial peripapillary capillary (RPC) plexi were evaluated. Logistic regression was applied to assess the association of ocular measurements with hypertension. GCC thickness was inversely associated with hypertension (odds ratio (OR): 0.98, 95% confidence interval (CI): 0.97-1). A rarefaction of VD of the ONH plexus at the inferior temporal sector (OR: 0.95, 95% CI: 0.91-0.99) and, conversely, a higher VD of the ONH and RPC plexi inside optic disc (OR: 1.07, 95% CI: 1.04-1.10; OR: 1.04, 95% CI: 1.02-1.06, respectively) were significantly associated with hypertension. A neuroretinal thinning involving GCC and a change in capillary density at the peripapillary network were related to the hypertension in older patients without hypertensive retinopathy. Assessing peripapillary retinal microvasculature using OCT-A may be a useful non-invasive approach to detect early microvascular changes due to hypertension

    Anastomosis configuration and technique following ileocaecal resection for Crohn's disease: a multicentre study

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    A limited ileocaecal resection is the most frequently performed procedure for ileocaecal CD and different anastomotic configurations and techniques have been described. This manuscript audited the different anastomotic techniques used in a national study and evaluated their influence on postoperative outcomes following ileocaecal resection for primary CD. This is a retrospective, multicentre, observational study promoted by the Italian Society of Colorectal Surgery (SICCR), including all adults undergoing elective ileocaecal resection for primary CD from June 2018 May 2019. Postoperative morbidity within 30 days of surgery was the primary endpoint. Postoperative length of hospital stay (LOS) and anastomotic leak rate were the secondary outcomes. 427 patients were included. The side to side anastomosis was the chosen configuration in 380 patients (89%). The stapled anastomotic (n = 286; 67%), techniques were preferred to hand-sewn (n = 141; 33%). Postoperative morbidity was 20.3% and anastomotic leak 3.7%. Anastomotic leak was independent of the type of anastomosis performed, while was associated with an ASA grade ≥ 3, presence of perianal disease and ileocolonic localization of disease. Four predictors of LOS were identified after multivariate analysis. The laparoscopic approach was the only associated with a reduced LOS (p = 0.017), while age, ASA grade ≥ 3 or administration of preoperative TPN were associated with increased LOS. The side to side was the most commonly used anastomotic configuration for ileocolic reconstruction following primary CD resection. There was no difference in postoperative morbidity according to anastomotic technique and configuration. Anastomotic leak was associated with ASA grade ≥ 3, a penetrating phenotype of disease and ileo-colonic distribution of CD

    National variations in perioperative assessment and surgical management of Crohn's disease: a multicentre study

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    Aim: Crohn's disease (CD) requires a multidisciplinary approach and surgery should be undertaken by dedicated colorectal surgeons with audited outcomes. We present a national, multicentre study, with the aim to collect benchmark data on key performance indicators in CD surgery, to highlight areas where standards of CD surgery excel and to facilitate targeted quality improvement where indicated. Methods: All patients undergoing ileocaecal or redo ileocolic resection in the participating centres for primary and recurrent CD from June 2018 to May 2019 were included. The main objective was to collect national data on hospital volume and practice variations. Postoperative morbidity was the primary outcome. Laparoscopic surgery and stoma rate were the secondary outcomes. Results: In all, 715 patients were included: 457 primary CD and 258 recurrent CD with a postoperative morbidity of 21.6% and 34.7%, respectively. Laparoscopy was used in 83.8% of primary CD compared to 31% of recurrent CD. Twenty-five hospitals participated and the total number of patients per hospital ranged from 2 to 169. Hospitals performing more than 10 primary CD procedures per year showed a higher adoption of laparoscopy and bowel sparing surgery. Conclusions: There is significant heterogeneity in the number of CD surgeries performed per year nationally in Italy. Our data suggest that high-volume hospitals perform more complex procedures, with a higher adoption of bowel sparing surgery. The rate of laparoscopy in high-volume hospitals is higher for primary CD but not for recurrent CD compared with low-volume hospitals

    The commissioning of the CUORE experiment: the mini-tower run

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    CUORE is a ton-scale experiment approaching the data taking phase in Gran Sasso National Laboratory. Its primary goal is to search for the neutrinoless double-beta decay in 130Te using 988 crystals of tellurim dioxide. The crystals are operated as bolometers at about 10 mK taking advantage of one of the largest dilution cryostat ever built. Concluded in March 2016, the cryostat commissioning consisted in a sequence of cool down runs each one integrating new parts of the apparatus. The last run was performed with the fully configured cryostat and the thermal load at 4 K reached the impressive mass of about 14 tons. During that run the base temperature of 6.3 mK was reached and maintained for more than 70 days. An array of 8 crystals, called mini-tower, was used to check bolometers operation, readout electronics and DAQ. Results will be presented in terms of cooling power, electronic noise, energy resolution and preliminary background measurements

    Results from the Cuore Experiment

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    The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for neutrinoless double beta decay that has been able to reach the 1-ton scale. The detector consists of an array of 988 TeO2 crystals arranged in a cylindrical compact structure of 19 towers, each of them made of 52 crystals. The construction of the experiment was completed in August 2016 and the data taking started in spring 2017 after a period of commissioning and tests. In this work we present the neutrinoless double beta decay results of CUORE from examining a total TeO2 exposure of 86.3kg yr, characterized by an effective energy resolution of 7.7 keV FWHM and a background in the region of interest of 0.014 counts/ (keV kg yr). In this physics run, CUORE placed a lower limit on the decay half- life of neutrinoless double beta decay of 130Te > 1.3.1025 yr (90% C. L.). Moreover, an analysis of the background of the experiment is presented as well as the measurement of the 130Te 2vo3p decay with a resulting half- life of T2 2. [7.9 :- 0.1 (stat.) :- 0.2 (syst.)] x 10(20) yr which is the most precise measurement of the half- life and compatible with previous results
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