153 research outputs found
Scalable Algorithms for Cloud Radio Access Network (C-RAN) Optimization
In the evolving scenario of 5G networks, resource allocation algorithms for the Cloud Radio Access Network (C-RAN) model have proven to be the key for managing ever increasing Capital Expenditure (CAPEX) and Operating Expenditure (OPEX) for mobile networks while ensuring high Quality of Service (QoS).
In Chapter 1 a brief overview of the main elements of the C-RAN and of the methodologies that are employed in this work is provided.
In Chapter 2, an exact scalable methodology for a static traffic scenario, based on lexicographic optimization, is proposed for the solution of a multi-objective optimization problem to achieve, among other goals, the minimization of the number of active nodes in the C-RAN while supporting reliability and meeting latency constraints. The optimal solution of the most relevant objectives for networks of several tens of nodes is obtained in few tens of seconds of computational time in the worst case. For the least relevant objective a heuristic is developed, providing near optimal solutions in few seconds of computing time.
In Chapter 3, an optimization framework for dynamic C-RAN reconfiguration is developed. The objective is to maintain C-RAN cost optimization, while minimizing the cost of virtual network function migration. Significant savings in terms of migrations (above 82% for primary virtual BBU functions and above 75% for backup virtual BBU functions) can be obtained with respect to a static traffic scenario, with execution time of the optimization algorithm below 20 seconds in the worst cases, making its application feasible for dynamic scenarios.
In Chapter 4, an alternative Column Generation model formulation is developed, and the quality of the computed lower bounds is evaluated. Further extensions from this baseline (e.g. Column Generation based heuristics, exact Branch&Price algorithms) are left as future work.
In Chapter 5, the main results achieved in this work are summarized, and several possible extensions are proposed
Calibrated Probabilistic QoT Regression for Unestablished Lightpaths in Optical Networks
Quality-of-Transmission (QoT) regression of unestablished lightpaths is a fundamental problem in Machine Learning applied to optical networks. Even though this problem is well-investigated in current literature, many state-of-the-art approaches either predict point-estimates of the QoT or make simplifying assumptions about the QoT distribution. Because of this, during lightpath deployment, an operator might take either overly-aggressive or overly-conservative decisions due to biased predictions.
In this paper, we leverage state-of-the-art Gradient Boosting Decision Tree (GBDT) models and recent advances in uncertainty calibration to perform QoT probabilistic regression for unestablished lightpaths. Calibration of a regression model allows for an accurate modeling of the QoT Cumulative Distribution Function (CDF) without any prior assumption on the QoT distribution. In our illustrative experimental results, we show that our calibrated GBDT model's predictions provide accurate confidence interval estimates, even when only few samples per lightpath configuration are available at training time
Potassium-Doped Para-Terphenyl: Structure, Electrical Transport Properties and Possible Signatures of a Superconducting Transition
Preliminary evidence for the occurrence of high-TC superconductivity in alkali-doped organic materials, such as potassium-doped p-terphenyl (KPT), were recently obtained by magnetic susceptibility measurements and by the opening of a large superconducting gap as measured by ARPES and STM techniques. In this work, KPT samples have been synthesized by a chemical method and characterized by low-temperature Raman scattering and resistivity measurements. Here, we report the occurrence of a resistivity drop of more than 4 orders of magnitude at low temperatures in KPT samples in the form of compressed powder. This fact was interpreted as a possible sign of a broad superconducting transition taking place below âŒ90 K in granular KPT. The granular nature of the KPT system appears to be also related to the âŒ20 K broadening of the resistivity drop around the critical temperature
Engineering Porous Silicon Nanowires with Tuneable Electronic Properties
Structural and electronic properties of silicon nanowires with pre-designed structures are investigated. Wires with distinct structure were investigated via advanced spectroscopic techniques such as X-ray absorption spectroscopy and Raman scattering as well as transport measurements. We show that wire structures can be engineered with metal assisted etching fabrication process via the catalytic solution ratios as well as changing doping type and level. In this way unique well-defined electronic configurations and density of states are obtained in the synthesized wires leading to different charge carrier and phonon dynamics in addition to photoluminescence modulations. We demonstrate that the electronic properties of these structures depend by the final geometry of these systems as determined by the synthesis process. These wires are characterized by a large internal surface and a modulated DOS with a significantly high number of surface states within the band structure. The results improve the understanding of the different electronic structures of these semiconducting nanowires opening new possibilities of future advanced device designs
Author Correction:Human ESCRT-III polymers assemble on positively curved membranes and induce helical membrane tube formation
An amendment to this paper has been published and can be accessed via a link at the top of the paper
Intensive insulin therapy increases glutathione synthesis rate in surgical ICU patients with stress hyperglycemia
OBJECTIVE:
The glutathione system plays an essential role in antioxidant defense after surgery. We assessed the effects of intensive insulin treatment (IIT) on glutathione synthesis rate and redox balance in cancer patients, who had developed stress hyperglycemia after major surgery.
METHODS:
We evaluated 10 non-diabetic cancer patients the day after radical abdominal surgery combined with intra-operative radiation therapy. In each patient, a 24-hr period of IIT, aimed at tight euglycemic control, was preceded, or followed, by a 24-hr period of conventional insulin treatment (CIT) (control regimen). Insulin was administered for 24 hours, during total parenteral nutrition, at a dosage to maintain a moderate hyperglycemia in CIT, and normoglycemic blood glucose levels in IIT (9.3\ub10.5 vs 6.5\ub10.3 mmol/L respectively, P<0.001; coefficient of variation, 9.7\ub11.4 and 10.5\ub11.1%, P = 0.43). No hypoglycemia (i.e., blood glucose < 3.9 mmol/L) was observed in any of the patients. Insulin treatments were performed on the first and second day after surgery, in randomized order, according to a crossover experimental design. Plasma concentrations of thiobarbituric acid reactive substances (TBARS) and erythrocyte glutathione synthesis rates (EGSR), measured by primed-constant infusion of L-[2H2]cysteine, were assessed at the end of each 24-hr period of either IIT or CIT.
RESULTS:
Compared to CIT, IIT was associated with higher EGSR (2.70\ub10.51 versus 1.18\ub10.29 mmol/L/day, p = 0.01) and lower (p = 0.04) plasma TBARS concentrations (2.2\ub10.2 versus 2.9\ub10.4 nmol/L).
CONCLUSIONS:
In patients developing stress hyperglycemia after major surgery, IIT, in absence of hypoglycemia, stimulates erythrocyte glutathione synthesis, while decreasing oxidative stress
Relazione tecnica e tabella contenente gli importi, le coordinate di bilancio di provenienza e di destinazione nonchĂ© le âStrutture di Ricercaâ destinatarie dei fondi di cui allo âElenco dei lavoriâ per lâanno 2020 del âProgramma triennale dei lavori pubblici 2020-2022â approvato con Delibera del 31 marzo 2021, numero 14.
Il presente rapporto tecnico si pone lâobiettivo di individuare gli importi da destinare alle âStrutture di ricercaâ di cui allo âelenco dei lavoriâ per lâanno 2020 del âProgramma triennale lavori pubblici 2020-2022â approvato con delibera del 31 marzo 2021, numero 14 con le relative coordinate di bilancio sia di provenienza che di destinazione secondo quanto previsto con riferimento al Decreto 25 gennaio 2019, âAggiornamento dellâallegato 1 del Decreto del Presidente della Repubblica 4 ottobre 2013, numero 132 âPiano dei conti integratoâ, ai sensi dellâarticolo 5 del medesimo D.P.R. e del comma 4, articolo 4 del Decreto Legislativo 31 maggio 2011, numero 91â
Allocazione delle risorse per lâattuazione del âProgramma dei Lavori Pubblici" per il Triennio 2020-2022 ed âElenco dei Lavoriâ 2020.
Per lâattuazione degli interventi edilizi dellâIstituto relativamente al triennio 2020-2022 si Ăš predisposto il quadro di dettaglio delle risorse che sono state rese disponibili per tale scopo, con riferimento alla opportuna allocazione delle medesime nel relativo Bilancio di previsione per lâannualitĂ 2021. Il rapporto a tal fine preparato dalla struttura tecnica denominata âTavolo Tecnico Permanente per il Patrimonio Immobiliare e i Lavori Pubbliciâ, Ăš stato redatto sulla scorta degli approfondimenti tecnici ed amministrativi compiuti in fase di istruttoria sulle richieste formulate dalle Strutture di ricerca ubicate su tutto il territorio nazionale, costituenti il quadro generale delle esigenze
I Lavori Pubblici nello âIstituto Nazionale di Astrofisicaâ nel triennio 2020 - 2022. Adozione dello schema di âProgramma Triennale Lavori Pubblici dello "Istituto Nazionale di Astrofisica" Triennio 2020-2022, "Elenco dei Lavoriâ per lâanno 2020, ed âElenco degli interventi sotto 100 mila euroâ.
Il rapporto tecnico contiene approfondimenti ai fini della adozione del âProgramma Triennale dei Lavori Pubblici 2020 â 2022â, nella sua articolazione annuale e triennale, volto alla riqualificazione, gestione, recupero, attraverso una attenta e corretta programmazione, dellâingente patrimonio immobiliare dellâEnte, caratterizzato prevalentemente da strutture di grande pregio storico, artistico, scientifico e paesaggistico. Il documento ha inoltre la finalitĂ di definire gli interventi da inserire nello âSchema di Programma Triennale dei Lavori Pubblici 2020-2022", in particolare nellââElenco dei Lavoriâ per lâanno 2020, selezionati in considerazione delle prioritĂ stabilite per Legge in relazione alle disponibilitĂ economiche autonome delle Strutture di Ricerca e della proposta di assegnazione dei fondi destinati ad interventi di edilizia nel Bilancio dellâEnte avanzata dal âTavolo Tecnico Permanente per il Patrimonio Immobiliare e i Lavori Pubbliciâ
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