Optimal selection of contracts and work shifts in multi-skill call centers

This paper deals with the problem of finding the most suitable contracts to be used when hiring the operators of a call center and deciding their optimal working schedule, to optimize the trade-off between the service level provided to the customers and the cost of the personnel. In a previous paper (Cordone et al. 2011), we proposed a heuristic method to quickly build an integer solution from the solution of the continuous relaxation of an integer linear programming model. In this paper, we generalize that model to take into account a much wider class of working contracts, allowing heterogeneous shift patterns, as well as legal constraints related to continuously active working environments. Since our original rounding heuristic cannot be extended to the new model, due to its huge size and to the involved correlations between different sets of integer variables, we introduce a more sophisticated heuristic based on decomposition and on a multi-level iterative structure. We compare the results of this heuristic with those of a Greedy Randomized Adaptive Search Procedure, both on real-world instances and on realistic random instances

Long-term outcomes of surgical aortic fenestration for complicated acute type B aortic dissections

IntroductionSurgical aortic fenestration has been used for treating ischemic complications of acute type B aortic dissection (ABAD). In the current endovascular era, surgical aortic fenestration may serve as an alternative for these patients after percutaneous failure. The purpose of this study is to describe our surgical suprarenal and infrarenal aortic fenestration technique, and to report the long-term outcomes of this approach in the management of complicated ABAD.MethodsWe retrospectively analyzed the in-hospital and long-term outcomes of 18 patients treated with either suprarenal (n = 10) or infrarenal surgical fenestration (n = 8) for complicated ABAD between 1988 and 2002. Suprarenal fenestration was performed through a thoracoabdominal incision in the 10th intercostal space, whereas patients treated with infrarenal fenestration underwent a midline laparotomy. A longitudinal aortotomy was performed and the true and false lumens were identified, followed by a wide resection of the intimal membrane.ResultsMedian age was 60 years (range, 48-82 years) and 89% (n = 16) were male. The in-hospital mortality was 22% (n = 4), which included two deaths after suprarenal fenestration and two deaths after infrarenal fenestration. In the remaining patients, full visceral, renal, and lower extremity function was recovered, except for 1 patient with paraplegia at admission in which the neurologic deficit was permanent. Median follow-up of the surviving patients was 10.0 years (interquartile range, 12.5; range, 0.5-20 years). During follow-up, none of the patients developed renal or visceral ischemia, or ischemic complications to the lower extremities, and no significant dilatations of the treated aortic segments were noted. Three of 14 patients with ABAD who were discharged alive expired during the follow-up period due to causes unrelated to the surgical procedure.ConclusionSurgical aortic fenestration represents an effective and durable option for treating ischemic complications of ABAD. Actually, this conservative surgical technique may serve as the alternative treatment in case of contraindications or failure of endovascular management of complicated ABAD

A dedicated pipeline to analyse solar data with INAF radio telescopes: SUNPIT (SUNdish PIpeline Tool)

This technical note describes SUNPIT (SUNdish PIpeline Tool) - the pipeline aimed at the imaging procedure and the data analysis of the radio solar data - and guides the user to properly reduce and analyse the solar data. SUNPIT is designed for radio data acquired with some radio telescopes of the INAF Network: the Sardinia Radio Telescope (SRT), and the Medicina Radio Telescope. The present user manual follows the development of software for solar imaging and data analysis of Active Regions (ARs), performed in the framework of the INAF Proposal "SunDish Project" (PI: A. Pellizzoni). This project has been active since 2018 with the goal of monitoring the solar atmosphere at high radio frequencies (at present 18 - 26 GHz) through single-dish observations. These solar observations will be enhanced through the upgrading of SRT with the new cryogenically cooled receivers, including a 19-feed in Q-band (33 - 50 GHz) and a 16-feed in W-band (75 - 116 GHz), in the context of the National Operative Programme (Programma Operativo Nazionale-PON); this project will provide in the near future an upgrading with the new receivers up to 116 GHz also for the Medicina and Noto Radio Telescopes, to provide the scientific community with the instrumentation suited to the study of the Universe at high radio frequencies. SUNPIT will be suitable for the data of these new forthcoming receivers, when available for the scientific community. SUNPIT produces a complete analysis of a solar map in about one hour, saving a directory which contains images, plots and several tables with the physical information of the solar disk and ARs (brightness temperatures, fluxes and spectral indices, with the respective errors). This pipeline – successfully tested – represents a crucial tool (1) to analyse solar images observed with the radio telescopes of the INAF Network, and (2) for the Space Weather monitoring network and forecast (soon available) along the solar cycle

C-band observations of supernova remnants with SRT: 2 - Calibrations

Following to the Astronomical Validation report n°6 (AV-rep-006; Egron et al. 2015) dedicated to the C-band imaging performances of SRT through the observation of two Supernova Remnants (3C157 and W44), this second note is devoted to the calibration of the resulting maps

C-band observations of supernova remnants with SRT: 1 - Imaging performances

We report on observations of Supernova Remnants (SNR) with SRT in the frame of Astronomical Validation (AV) test activities. These tests are aimed to assess single-dish imaging performances of “SRT first light receivers” coupled with Total Power (TP) backend and related hw/sw subsystems/procedures (including innovative ad hoc imaging techniques based on OTF scans)

Single-dish total power imaging of bright sources: mapping of 3c295 in C-band and K-band

In the frame of AV tests “Single-­‐Dish Total Power Imaging of Bright Sources (I:s/w test)” (AV SNR1 test) we performed C band and K band (only central feed) imaging of point-­‐like bright calibration sources (i.e. 3C295 in particular)