New models and algorithms for the timetables of Italian high schools

The thesis investigates new timetabling problems, which are motivated by the com- plex case of Italian schools. Generally speaking, the High School Timetabling Problem is aimed at giving the right order to the meetings between groups of students and teachers. However, it requires to pre-assign teachers to the classes, i.e. establishing which teacher will teach each subject in each class. This problem is called Class Teacher Assignment Problem and is faced by a mixed integer programming formulation, which also aims at easing the solution of the following High School Timetabling Problem. Moreover, the thesis shows that Class Teacher Assignment Problem can also be adapted to face the case where teachers must give lectures in more than one school (Multi-school Timetabling Problem). In particular, this thesis investigates a complex variant of the High School Timetabling problem w.r.t. a given assignment of teachers to classes. This problem presents requirements, which en- force to (i) provide teachers with the same idle times, (ii) avoid consecutive days with heavy workload, (iii) limit multiple daily lessons for each class, (iv) introduce shorter time units to di↵erentiate entry and exit times. An integer programming model is presented for this problem, which is denoted by Italian High School Timetabling Problem [IHSTP]. However, requirements (i), (ii), (iii) and (iv) cannot be expressed according to the current XML High School Time-Table [XHSTT] standard. Since the [IHSTP] model is very hard to solve by an off-the-shelf solver, a two-step optimization method is presented: the first step optimally assigns teachers to lesson times and the second step assigns classes to teachers. An extensive experimentation is performed on the model by realistic and real instances from Italian schools, as well as benchmark instances from the literature. Finally, the experiments show that the method is effective in solving both this new problem and the simplified problem without the new requirements

Effect of Chain-Length and Countersurface on the Tribochemistry of Bulk Zinc Polyphosphate Glasses

Zinc polyphosphate glasses are considered to be chiefly responsible for the anti-wear efficiency of ZnDTP tribofilms. In this work, the tribochemical properties of amorphous bulk zinc polyphosphates of different chain lengths (ranging from zinc metaphosphate to zinc pyrophosphate) have been investigated. Tribological tests on bulk polyphosphate discs have been carried out using steel and quartz balls as counter-surfaces in a poly-α-olefin (PAO) bath at room temperature. The composition in the wear track and on the contact region of the balls has been monitored by small-area and imaging X-ray photoelectron spectroscopy (i-XPS). The XPS analysis revealed that the composition of short-chain-length polyphosphates remained unchanged following tribological stress. Long-chain-length polyphosphates are depolymerized in the wear track as a consequence of a tribochemical reaction. By comparing the results obtained using quartz and steel balls, it could be observed that while the reaction of iron oxide with the polyphosphates certainly plays a role in the depolymerization of the samples under sliding conditions, pressure and shear stress alone and also in the presence of water or oil-oxidized species are able to depolymerize the glass when an inert material is used as counterpart; the composition of the wear track, in this case, is dependent on the applied load. All samples were able to form an adhesive, glassy transfer film on both steel and quartz balls, but the short-chain-length polyphosphates showed a lower friction coefficient and wear coefficient. The results suggest a third-body mechanism with the polyphosphates acting as a solid lubricant. Differences in tribological behavior of the different-chain-length polyphosphates are attributable to their mechanical and rheological propertie

Polymer-Brush Lubrication in Oil: Sliding Beyond the Stribeck Curve

We report a highly effective macroscopic, non-aqueous lubrication strategy, employing polymer-brush-based surface modification. Poly(alkyl methacrylates) with hexyl, dodecyl and octadecyl side chains have been prepared on both silicon and iron substrates by means of surface-initiated atom-transfer radical polymerisation. Frictional properties of the three polymers have been evaluated in hexadecane, ethanol and toluene. For the case of the poly(dodecyl methacrylate), the study additionally involved nine base lubricating fluids of different chemical natures, with viscosities ranging from 4 to 2,200cSt at 20°C. By constructing a set of Stribeck curves at low values of speed×viscosity (at constant load), it was possible to identify an extended hydrodynamic lubrication regime and, for P12MA-based coatings, a low-friction, brush-lubrication regime, reinforced by time-dependant effects, which appeared to replace the mixed and boundary regimes observed for conventional lubricants. Self-mated poly(dodecyl methacrylate) brushes maintained low coefficient-of-friction values (e.g. 0.012 in hexadecane) over thousands of reciprocating cycles (>100m total distance) under low speed×viscosity conditions (0.1cm/s and 4cSt

Chain-length-identification strategy in zinc polyphosphate glasses by means of XPS and ToF-SIMS

The surface chemistry of amorphous zinc polyphosphates of different compositions (ranging from zinc metaphosphate to zinc orthophosphate) has been investigated by means of X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary-ion mass spectroscopy (ToF-SIMS). The identification of the chain length of zinc polyphosphates by XPS was on the basis of the integrated intensity ratio of the bridging (P-O-P) and nonbridging (P = O and P-O-M) oxygen peaks used for fitting the oxygen 1s signal, the shift of the P 2p3/2 signal towards lower binding energies and the modified Auger parameter towards higher values as the zinc content increases. The discrimination of the polyphosphate chain lengths was also achieved by ToF-SIMS, by comparing the intensities of selected characteristic phosphate fragments. Both techniques appear to be suitable for the investigation of polyphosphate glasses in applications such as tribology, where there is a need to identify the chain length present in the outermost monolayer of the film. Fourier-transform infrared (FT-IR) spectroscopy was used to characterize the bulk compounds. The FT-IR studies showed that long-chain structures linked through P-O-P bonds predominate in the metaphosphate composition, while when the zinc content is increased, the chains become shorter, ultimately being replaced by PO4 monomers in the orthophosphate composition. Figure

High quality timetables for Italian schools

This work introduces a complex variant of the timetabling problem, which is motivated by the case of Italian schools. The new requirements enforce to (i) provide teachers with the same idle times, (ii) avoid consecutive days with heavy workload, (iii) limit multiple daily lessons for each class, (iv) introduce shorter time units to differentiate entry and exit times. We present an integer programming model for this problem, which is denoted by Italian High School Timetabling Problem (IHSTP). However, requirements (i), (ii), (iii) and (iv) cannot be expressed according to the current XHSTT standard. Since the IHSTP model is very hard to solve by an off-the-shelf solver, we present a two-step optimization method: the first step optimally assigns teachers to lesson times and the second step assigns classes to teachers. An extensive experimentation is performed on the model by realistic and real instances from Italian schools, as well as benchmark instances from the literature. Finally, the experiments show that the method is effective in solving both this new problem and the simplified problem without the new requirements

Economia dell'intersoggettivita: l'importanza degli "altri" nelle dinamiche economiche.

Il presente lavoro, partendo dall'indagine della filosofia di Adam Smith, si propone di analizzare i rapporti tra individuo e società in ambito economico. In particolare l’attenzione è focalizzata sulla relazione che intercorre tra interesse individuale ed interesse pubblico e sul comportamento umano nelle questioni di scelta. A confronto vengono posti essenzialmente due modelli economici: l’economia positiva di matrice utilitarista che assume come unico modello comportamentale quello dell’homo oeconomicus, un individuo razionale ed esclusivamente auto-interessato; e l’economia intersoggettiva che prende in considerazione nelle sue dinamiche anche una dimensione normativa ed una dimensione relazionale, tenendo sempre conto del rapporto di interdipendenza che ci lega agli “altri” soggetti. All'affermazione dell’individualismo assiologico in ambito economico si è cercato di opporre, attraverso una rilettura di Smith stesso e attraverso l’analisi di alcuni autori contemporanei come Sen, Sennet e Akerlof, un economia più umana in grado di uscire da una dimensione esclusivamente tecnica tenendo conto di questioni identitarie, di equità e delle forme di cooperatività e reciprocità che intercorrono tra gli uomini e fanno sì che risulti irrinunciabile una prospettiva intersoggettiva dell’economia se con essa si vogliono ottenere risultati che puntino realmente a migliorare il benessere e la felicità umana

Analisi comparativa dei metaboliti presenti nelle urine di soggetti sani ed affetti da carcinoma alla vescica

non disponibileFor several years proteomics research has been expected to lead to the finding of new markers that will translate into clinical tests applicable to samples such as serum, plasma and urine: so-called in vitro diagnostics (IVDs). Attempts to implement technologies applied in proteomics as 2DE, Immuno Blotting, Mass Spectrometry have initiated constructive discussions on opportunities and challenges inherent in such a translation process also with respect to the use of multi-marker profiling approaches and pattern signatures in IVD. It is mandatory to fulfil requirements in routine IVD, including disease prevention, diagnosis, prognosis, and treatment monitoring or follow up among others. To fulfill IVD requirements, it is essential to provide diagnostic tests that allow for definite and reliable diagnosis tied to a decision on interventions (prevention, treatment, or non treatment), meet stringent performance characteristics for each analyte (in particular test accuracy, including both precision of the measurement and trueness of the measurement), and provide adequate diagnostic accuracy, i.e., diagnostic sensitivity and diagnostic specificity, determined by the desired positive and negative predictive values which depend on disease frequency. The fulfilment of essential IVD requirements is mandatory in the regulated environment of modern diagnostics. Addressing IVD needs at an early stage can support a timely and effective transition of findings and developments into routine diagnosis. IVD needs reflect features that are useful in clinical practice. This helps to generate acceptance and assists the implementation process. The medical need for relevant biomarkers is enormous. This is particularly true for the many types of cancer, but other diseases such as Type 1 diabetes (DMT1) also lack useful and adequate diagnostic markers with high specificity and sensitivity. Despite advances in imaging technologies for early detection of diseases, proteomic and peptidomic multiplex techniques and metabolomics statistical analysis have evolved in recent years

Tribochemistry of Bulk Zinc Metaphosphate Glasses

Zinc polyphosphate glasses are the principal component of the antiwear tribofilms formed on steel surfaces in the presence of additives, such as zinc dialkyldithiophosphates. In this work, amorphous, zinc metaphosphate glasses have been synthesized and characterized by means of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), elemental analysis, and X-ray photoelectron spectroscopy (XPS). Tribological tests were performed by rubbing steel balls against the zinc metaphosphate discs in a poly-α-olefin (PAO) bath at room temperature. XPS was used in order to characterize the tribostressed areas on both metaphosphate discs and steel balls. A transfer film, constituted of iron and zinc polyphosphates, was formed on the contact area of the balls. This transfer film was found to reduce friction and prevent ball wear. A reduction in the relative intensities of XPS signals related to bridging-oxygen species and a binding energy shift of 0.4eV of the P 2p toward lower values demonstrated the presence of shorter-chain-length phosphates inside the tribo-tracks on the discs. Furthermore, iron was transferred to the glass during the tribological tests. A tribochemical reaction between zinc metaphosphate and iron oxide has been proposed as an explanation for the depolymerization of the glass and the formation of iron phosphat

Compared genomics of the strand switch region of Leishmania chromosome 1 reveal a novel genus-specific gene and conserved structural features and sequence motifs

BACKGROUND: Trypanosomatids exhibit a unique gene organization into large directional gene clusters (DGCs) in opposite directions. The transcription "strand switch region" (SSR) separating the two large DGCs that constitute chromosome 1 of Leishmania major has been the subject of several studies and speculations. Thus, it has been suspected of being the single replication origin of the chromosome, the transcription initiation site for both DGCs or even a centromere. Here, we have used an inter-species compared genomics approach on this locus in order to try to identify conserved features or motifs indicative of a putative function. RESULTS: We isolated, and compared the structure and nucleotide sequence of, this SSR in 15 widely divergent species of Leishmania and Sauroleishmania. As regards its intrachromosomal position, size and AT content, the general structure of this SSR appears extremely stable among species, which is another demonstration of the remarkable structural stability of these genomes at the evolutionary level. Sequence alignments showed several interesting features. Overall, only 30% of nucleotide positions were conserved in the SSR among the 15 species, versus 74% and 62% in the 5' parts of the adjacent XPP and PAXP genes, respectively. However, nucleotide divergences were not distributed homogeneously along this sequence. Thus, a central fragment of approximately 440 bp exhibited 54% of identity among the 15 species. This fragment actually represents a new Leishmania-specific CDS of unknown function which had been overlooked since the annotation of this chromosome. The encoded protein comprises two trans-membrane domains and is classified in the "structural protein" GO category. We cloned this novel gene and expressed it as a recombinant green fluorescent protein-fused version, which showed its localisation to the endoplasmic reticulum. The whole of these data shorten the actual SSR to an 887-bp segment as compared with the original 1.6 kb. In the rest of the SSR, the percentage of identity was much lower, around 22%. Interestingly, the 72-bp fragment where the putatively single transcription initiation site of chromosome 1 was identified is located in a low-conservation portion of the SSR and is itself highly polymorphic amongst species. Nevertheless, it is highly C-rich and presents a unique poly(C) tract in the same position in all species. CONCLUSION: This inter-specific comparative study, the first of its kind, (a) allowed to reveal a novel genus-specific gene and (b) identified a conserved poly(C) tract in the otherwise highly polymorphic region containing the putative transcription initiation site. This allows hypothesising an intervention of poly(C)-binding proteins known elsewhere to be involved in transcriptional control