On the positivity of MSbar parton distributions

We revisit our argument that shows that parton distribution Functions (PDFs) in the MSbar{ scheme are non-negative in the perturbative region, with the main goals of elucidating its domain of validity and clarifying its theoretical underpinnings. We specifically discuss recent results proving that PDFs can turn negative at sufficiently low scale, we clarify quantitatively various aspects of our derivation of positivity in the perturbative region, and we provide an estimate for the scale above which PDF positivity holds

Development of a Flexible Lead-Free Piezoelectric Transducer for Health Monitoring in the Space Environment

In this work we report on the fabrication process for the development of a flexible piezopolymeric transducer for health monitoring applications, based on lead-free, piezoelectric zinc oxide (ZnO) thin films. All the selected materials are compatible with the space environment and were deposited by the RF magnetron sputtering technique at room temperature, in view of preserving the total flexibility of the structures, which is an important requirement to guarantee coupling with cylindrical fuel tanks whose integrity we want to monitor. The overall transducer architecture was made of a c-axis-oriented ZnO thin film coupled to a pair of flexible Polyimide foils coated with gold (Au) electrodes. The fabrication process started with the deposition of the bottom electrode on Polyimide foils. The ZnO thin film and the top electrode were then deposited onto the Au/Polyimide substrates. Both the electrodes and ZnO layer were properly patterned by wet-chemical etching and optical lithography. The assembly of the final structure was then obtained by gluing the upper and lower Polyimide foils with an epoxy resin capable of guaranteeing low outgassing levels, as well as adequate thermal and electrical insulation of the transducers. The piezoelectric behavior of the prototypes was confirmed and evaluated by measuring the mechanical displacement induced from the application of an external voltage

Design of the Test Section for the Experimental Validation of Antipermeation and Corrosion Barriers for WCLL BB

Tritium permeation into the Primary Heat Transfer System (PHTS) of DEMO and ITER reactors is one of the challenging issues to be solved in order to demonstrate the feasibility of nuclear fusion power plants construction. Several technologies were investigated as antipermeation and corrosion barriers to reduce the tritium permeation flux from the breeder into the PHTS. Within this frame, alumina coating manufactured by Pulsed Laser Deposition (PLD) and Atomic Layer Deposition (ALD) are two of the main candidates for the Water Cooled Lithium Lead (WCLL) Breeder Blanket (BB). In order to validate the performance of the coatings on relevant WCLL BB geometries, a mock-up was designed and will be characterized in an experimental facility operating with flowing lithium-lead, called TRIEX-II. The present work aims to illustrate the preliminary engineering design of a WCLL BB mock-up in order to deeply investigate permeation of hydrogen isotopes through PHTS water pipes. The permeation tests are planned in the temperature range between 330 and 500 °C, with hydrogen and deuterium partial pressure in the range of 1–1000 Pa. The hydrogen isotopes transport analysis carried out for the design and integration of the mock-up in TRIEX-II facility is also shown

Crown-Ether Functionalized Graphene Oxide Membrane for Lithium Recovery from Water

The massive worldwide transition of the transport sector to electric vehicles has dramatically increased the demand for lithium. Lithium recovery by means of ion sieves or supramolecular chemistry has been extensively studied in recent years as a viable alternative approach to the most common extraction processes. Graphene oxide (GO) has also already been proven to be an excellent candidate for water treatment and other membrane related applications. Herein, a nanocomposite 12-crown-4-ether functionalized GO membrane for lithium recovery by means of pressure filtration is proposed. GO flakes were via carbodiimide esterification, then a polymeric binder was added to improve the mechanical properties. The membrane was then obtained and tested on a polymeric support in a dead-end pressure setup under nitrogen gas to speed up the lithium recovery. Morphological and physico-chemical characterizations were carried out using pristine GO and functionalized GO membranes for comparison with the nanocomposite. The lithium selectivity was proven by both the conductance and ICP mass measurements on different sets of feed and stripping solutions filtrated (LiCl/HCl and other chloride salts/HCl). The membrane proposed showed promising properties in low concentrated solutions (7 mg(Li)/L) with an average lithium uptake of 5 mg(Li)/g in under half an hour of filtration time

Partie polityczne i systemy wyborcze

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Partie polityczne i systemy wyborcze

The essay deals with the topic of the relationship between parties and electoral systems. The author chooses to follow a historical perspective, leaving out both the influence of parties on electoral systems and the impact of electoral systems on the role and the organization of political parties. In the first part, the essay focuses on the transformation of the electoral law for the Chamber of Deputies from a proportional system to a majority system, untill the current “Italicum” system, remitted to the Constitutional Court for a legitimacy judgement. The second part deals with the characteristics of the new electoral system and with the (also paradoxal) effects that it could produce on the Italian political system. In the conclusions, the author mentions the law proposal concerning the discipline of political parties which is structured considering that the traditional model of party's organization is progressively disappearing.Il saggio affronta il tema dal rapporto tra partiti e sistemi elettorali secondo un approccio evolutivo, tralasciando sia il tema relativo all’influenza dei partiti sui sistemi elettorali, sia quello concernente i riflessi e i condizionamenti dei sistemi elettorali sulla vita, il ruolo e l’organizzazione dei partiti.In una prima parte è affrontata l’evoluzione storica del sistema elettorale per la Camera dei deputati delineando come, dopo una prima parte improntata al sistema proporzionale, le esigenze di maggiore stabilità politica abbiano spinto ad una svolta in senso maggioritario, culminata nel cd. “Italicum”, il sistema elettorale attualmente vigente per la sola Camera.Nella seconda parte sono illustrate le caratteristiche fondamentali del nuovo sistema elettorale, tutt’ora sub iudice dinanzi alla Corte Costituzionale, mettendo in evidenza il possibile impatto e gli effetti distorti che potrebbero prodursi sul sistema politico italiano. Nelle conclusioni, si dà conto della proposta di legge di disciplina dei partiti politici attualmente all’esame del Parlamento e di come questa tenga conto del fatto che il modello classico di organizzazione di partito stia progressivamente scomparendo.Niniejszy artykuł poświęcony jest ewolucji relacji zachodzących między partiami a systemami wyborczymi. Autor pomija zarówno tematykę wpływu partii politycznych na systemy wyborcze, jak i wpływu systemów wyborczych na rozwój, rolę i organizację partii. W pierwszej części pracy przedstawione zostały poszczególne systemy wyborcze do włoskiej Izby Deputowanych, począwszy od ordynacji proporcjonalnej, poprzez przyjęcie większościowego systemu wyborczego i kończąc na obecnie obowiązującej ordynacji zwanej Italicum. W drugiej części pracy Autor omawia najważniejsze cechy nowej ordynacji wyborczej, której konstytucyjność jest obecnie badana przez Sąd Konstytucyjny, podkreślając przy tym jej, być może niekorzystny, wpływ na włoski system polityczny. W podsumowaniu Autor odnosi się do projektu ustawy o partiach politycznych, nad którą właśnie pracuje Parlament, stwierdzając, że projekt ten daje wyraz postępującemu zanikowi tradycyjnego modelu organizacji partii

Thermally evaporated Cu-Co top spin valve with random exchange bias

A cobalt-copper top spin valve was prepared by thermal evaporation of a stack of ferromagnetic thin films separated by thin layers of the diamagnetic metal, with a cap layer containing an antiferromagnetic AFM exchange-biasing material. A nonconventional top AFM layer was used, in order to optimize the multilayer roughness and to avoid electrical interference with metallic layers; it consists of a composite material easily processed by means of optical lithography, basically a polymeric matrix composite with a dispersion of nickel oxide microparticles. Magnetization and magnetoresistance measurements were performed from 4 to 300 K. The measurements of both quantities indicate random pinning action of the top AFM layer, resulting in a small exchange-bias field and in asymmetric magnetization and magnetoresistance curves. A simple model explains the observed physical effect

Generation of induced pluripotent stem cell line, CSSi004-A (2962), from a patient diagnosed with Huntington's disease at the presymptomatic stage

Huntington's disease (HD) is an incurable, autosomal dominant, hereditary neurodegenerative disorder that typically manifests itself in midlife. This pathology is linked to the deregulation of multiple, as yet unknown, cellular processes starting before HD onset. A human iPS cell line was generated from skin fibroblasts of a subject at the presymptomatic life stage, carrying a polyglutamine expansion in HTT gene codifying Huntingtin protein. The iPSC line contained the expected CAG expansion, expressed the expected pluripotency markers, displayed in vivo differentiation potential to the three germ layers and had a normal karyotype