Elastodynamic analysis of a gear pump. Part I: Pressure distribution and gear eccentricity

A non-linear lumped kineto-elastodynamic model for the prediction of the dynamic behaviour of external gear pumps is presented. It takes into account the most important phenomena involved in the operation of this kind of machines. Two main sources of noise and vibration can be considered: pressure and gear meshing. Fluid pressure distribution on gears, which is time-varying, is computed and included as a resultant external force and torque acting on the gears. Parametric excitations due to time-varying meshing stiffness, the tooth profile errors (obtained by a metrological analysis), the backlash effects between meshing teeth, the lubricant squeeze and the possibility of tooth contact on both lines of action were also included. Finally, the torsional stiffness and damping of the driving shaft and the non-linear behaviour of the hydrodynamic journal bearings were also taken into account. Model validation was carried out on the basis of experimental data concerning case accelerations and force reactions. The model can be used in order to analyse the pump dynamic behaviour and to identify the effects of modifications in design and operation parameters, in terms of vibration and dynamic forces.Part I is devoted to the calculation of the gear eccentricity in the steady-state condition as a result of the balancing between mean pressure loads, mean meshing force and bearing reactions, while in Part II the meshing phenomena are fully explained and the main simulation results are presented.     

Intensive weight loss combining flexible dialysis with a personalized,ad libitum,coach‐assisted diet program. A “pilot” case series

Obesity is a growing problem on dialysis. The best approach to weight loss has not been established. The risks of malnutrition may offset the advantages of weight loss. Personalized hemodialysis schedules, with an incremental approach, are gaining interest; to date, no studies have explored its potential in allowing weight loss. This case series reports on combining flexible, incremental hemodialysis, and intensive weight loss. Setting: a small Dialysis Unit, following incremental personalized schedules (2–6 sessions/week, depending on residual function), tailored to an equivalent renal clearance >12 mL/min. Four obese and two overweigh patients (5 male, 1 female; age: 40–63 years; body mass index [BMI] 31.1 kg/m²) were enrolled in a coach‐assisted weight loss program, with an “ad libitum” approach (3–6 foods/day chosen on the basis of their glycemic index and glycemic load). The diet consists of 8 weeks of rapid weight loss followed by 8–12 weeks of maintenance; both phases can be repeated. This study measures weight loss, side effects, and patients' opinions. Over 12–30 months, all patients lost weight (median ?10.3 kg [5.7–20], median ΔBMI–3.2). Serum albumin (pre‐diet 3.78; post‐diet 3.83 g/dL), hemoglobin (pre‐diet 11; post‐diet 11.2 g/dL), and acid–base balance (HCO₃ pre‐diet: 23.3; post‐diet: 23.4 mmol/L) remained stable, with decreasing needs for erythropoietin and citrate or bicarbonate supplements. Calcium‐phosphate‐parathyroid hormone (PTH) balance improved (PTH‐pre 576; post 286 pg/mL). Three out of 4 hypertensive patients discontinued, 1 decreased antihypertensives. None experienced severe side effects. Patient satisfaction was high (9 on a 0–10 analog scale). Personalized, incremental hemodialysis schedules allow patient enrollment in intensive personalized weight loss programs, with promising results.     

Probability of inelastic nuclear interactions of high-energy protons in a bent crystal

Probability of inelastic nuclear interactions in a short bent silicon crystal for its orientations optimal for channeling and volume reflection was investigated using 400 GeV/c protons of the CERN SPS. The contribution of nuclear interactions from channeled protons was observed to be about 3–4% of the probability for the amorphous orientation. For the crystal orientation optimal for volume reflection the nuclear interaction probability of protons was a few percents larger than in the amorphous case. It was shown that in the limiting case of a quasi parallel beam realizing for the collider beam halo the inelastic nuclear losses should decrease by more than five times, which is an additional advantage of a crystal as a primary collimator for the LHC collimation system.     

A concerted study using binding measurements, X-ray structural data, and molecular modeling on the stereochemical features responsible for the affinity of 6-arylpyrrolo[2,1-d][1,5]benzothiazepines toward mitochondrial benzodiazepine receptors

The 7-(acyloxy)-6-arylpyrrolo[2,1-d][1,5]benzothiazepine derivatives have been recently proposed as a new class of ligands specific for the mitochondrial benzodiazepine receptor (Fiorini et al. J. Med. Chem. 1994, 37, 1427-1438) (Greco et al. J. Med. Chem. 1994, 37, 4100-4108). In this paper we report the X-ray crystallographic structures of three potent (1-3) and two inactive (4 and 5) previously described benzothiazepines, as well as binding affinity constants for two newly assayed analogs in which the acyloxy side chain was replaced by a methoxy group (6) or removed (7). Structure-affinity relationships and molecular mechanics calculations performed using crystal structures as references have led to a revised 3D pharmacophore model accounting for all the data available up until now. Interestingly, the hypothetical receptor-bound conformations of 1-3 display a considerable degree of similarity with their crystal geometries. Additional calculations have confirmed that the poor affinities of benzothiazepines bearing an aroyloxy group (4 and 5) should be ascribed to the steric and/or electronic features of the side chain aryl moieties rather than to unfavorable conformational properties.     

Magnetic resonance imaging and67ga scan versus computed tomography in the staging and in the monitoring of mediastinal malignant lymphoma: a prospective pilot study

Purpose: To assess the potential value of magnetic resonance imaging (MRI) combined with⁶⁷Ga single-photon emission computed tomography (SPECT) versus computed tomography (CT) in the staging and in the monitoring of mediastinal malignant lymphoma. Materials and methods: Twenty-three patients, referred to our institute for the evaluation of lymphoma, underwent CT,⁶⁷Ga scan, and MRI between April 1993 and February 1996 at sequential intervals. The tests studied (MRI,^67Ga, and CT) were performed according to the following schedule: 1) before start of therapy; 2) after four courses of chemotherapy; and 3) 2, 6, 12, and 18 months after the end of treatment. Results: All patients studied at the time of diagnosis had abnormal gallium accumulation in the mediastinum as well as pathologic CT and pathologic signal intensity at MRI. Six months after the end of treatment full consistency was found between the results of MRI and SPECT, whereas during treatment and 2 months after the end of therapy MRI and⁶⁷Ga scan were not in agreement in nine patients. In the 23 patients in follow-up, in CT there were nine false-positive and three false-negative findings; in SPECT three false negatives; in MRI one false positive and one false negative. Conclusion: MRI can give morphologic information similar to CT, even superior due to multiplanarity and with major precision in the distinction between fibrosis and active disease. MRI is thus an alternative to CT. The association with SPECT allows a great diagnostic accuracy in the positive and negative predictive value.     

Invasive fungal infections in patients with hematologic malignancies (aurora project): lights and shadows during 18-months surveillance

The aim of this multicenter prospective study was to evaluate the incidence of invasive fungal infections (IFIs) in adult and pediatric patients with hematologic malignancies, involving nine nosocomial facilities in Southern Italy over a period of 18 months. Furthermore, results of an environmental microbial surveillance routinely carried out in some of the enrolled hospitals are reported. A total of 589 onco-hematological patients were enrolled and 27 IFIs were documented. The main infections were caused by yeasts, more than filamentous fungi (overall incidence of 2.7% and 1.9%, respectively). The yeasts were mainly represented by Candida spp. (87.5%), all isolated by blood cultures; C. parapsilosis was the most common species. Among mould infections, the most frequent site was the lung, with regard to aspergillosis (81.8%). In six of the 10 patients with suspected aspergillosis, the diagnosis was made by the detection of galactomannan and (1,3)-β-d-glucan antigens. The microbiological surveillance carried out on 156 air, 312 water and 312 surface samples revealed low environmental contamination: Alternaria alternata was the only fungus isolated from two surface samples. Our data, especially the low occurrence of filamentous fungi, suggest a particular local epidemiology. Further studies are needed to confirm this microbiological trend in onco-hematological patients in Southern Italy, the results of which might be helpful to improve the management of these patients.     

Improving agile requirements: the Quality User Story framework and tool

User stories are a widely adopted requirements notation in agile development. Yet, user stories are too often poorly written in practice and exhibit inherent quality defects. Triggered by this observation, we propose the Quality User Story (QUS) framework, a set of 13 quality criteria that user story writers should strive to conform to. Based on QUS, we present the Automatic Quality User Story Artisan (AQUSA) software tool. Relying on natural language processing (NLP) techniques, AQUSA detects quality defects and suggest possible remedies. We describe the architecture of AQUSA, its implementation, and we report on an evaluation that analyzes 1023 user stories obtained from 18 software companies. Our tool does not yet reach the ambitious 100 % recall that Daniel Berry and colleagues require NLP tools for RE to achieve. However, we obtain promising results and we identify some improvements that will substantially improve recall and precision.     

Survival with short‐daily hemodialysis: Association of time,site, and dose of dialysis

In thrice‐weekly hemodialysis, survival correlates with the length of time (t) of each dialysis and the dose (Kt/V), and deaths occur most frequently on Mondays and Tuesdays. We studied the influence of t and Kt/V on survival in 262 patients on short‐daily hemodialysis (SDHD) and also noted death rate by weekday. Contingency tables, Kaplan‐Meier analysis, regression analysis, and stepwise Cox proportional hazard analysis were used to study the associations of clinical variables with survival. Patients had been on SDHD for a mean of 2.1 (range 0.1–11) years. Mean dialysis time was 12.9 ± 2.3 h/wk and mean weekly stdKt/V was 2.7 ± 0.5. Fifty‐two of the patients died (20%) and 8‐year survival was 54 ± 5%. In an analysis of 4 groups by weekly dialysis time, 5‐year survival continuously increased from 45 ± 8% in those dialyzing <12 hours to 100% in those dialyzing >15 hours without any apparent threshold. There was no association between Kt/V and survival. In Cox proportional hazard analysis, 4 factors were independently associated with survival: age in years Hazard Ratio (HR)=1.05, weekly dialysis hours HR=0.84, home dialysis HR=0.50, and secondary renal disease HR=2.30. Unlike conventional HD, no pattern of excessive death occurred early in the week during SDHD. With SDHD, longer time and dialysis at home were independently associated with improved survival, while Kt/V was not. Homedialysis and dialysis 15+ h/wk appear to maximize survival in SDHD.     

Second Cancer Onset in Myeloproliferative Neoplasms: What,When, Why?

The risk of developing a solid cancer is a major issue arising in the disease course of a myeloproliferative neoplasm (MPN). Although the connection between the two diseases has been widely described, the backstage of this complex scenario has still to be explored. Several cellular and molecular mechanisms have been suggested to link the two tumors. Sometimes the MPN is considered to trigger a second cancer but at other times both diseases seem to depend on the same source. Increasing knowledge in recent years has revealed emerging pathways, supporting older, more consolidated theories, but there are still many unresolved issues. Our work aims to present the biological face of the complex clinical scenario in MPN patients developing a second cancer, focusing on the main cellular and molecular pathways linking the two diseases.     

Daily Dialysis: Toward a New Standard in Well‐Being

Daily hemodialysis (DHD) is a promising option; however, logistic obstacles and clinical perplexities limit its dissemination. Understanding the mechanisms of, and the time until, the onset of improved well‐being may help to quantify clinical advantages and to define the minimum length of a “trial” of daily dialysis. By following 30 patients treated in 4 centers, this study aimed to determine how long a period of time is needed until a patient experiences subjective improvement. From November 1998 to November 2000, 30 patients tried at least 2 weeks of short daily dialysis in four Northern Italian centers of Piemonte and Valle d'Aosta. The DHD (2 – 3 hours; blood flow 270 – 350 mL/min; individual HCO₃, Na, K) was performed at home or in a center. Motivations to try DHD, fears and concerns regarding DHD, and changes in perceived well‐being were assessed by semi‐structured interview. The main clinical indications for a trial of DHD were poor tolerance of conventional treatment, cardiovascular disease, and hypertension or hypotension; only 6 patients had no comorbidity at start. The patients' main reasons for choosing DHD were related to job problems and the search for a better treatment. Most of the patients continued DHD because of improved well‐being; logistic reasons accounted for the drop‐outs (5 patients). The main fears were related to logistic aspects, vascular access problems, and excessive involvement of the partner on home dialysis. Improved well‐being was reported by 28 of 30 patients; 2 patients reported no difference. Subjective improvement was perceived within 2 weeks in 22 of 30 patients, and within 1 month in 28 of 30 patients. An offer of a 2 – 4 week trial of DHD may help patients and caregivers to determine whether subjective and objective benefits outweigh logistic problems and whether a permanent transfer to DHD is worthwhile.