Ferroelectricity and isotope effects in hydrogen-bonded KDP crystals

Based on an accurate first principles description of the energetics in H-bonded KDP, we conduct a first study of nuclear quantum effects and of the changes brought about by deuteration. Cluster tunneling involving also heavy ions is allowed, the main effect of deuteration being a depletion of the proton probability density at the O-H-O bridge center, which in turn weakens its proton-mediated covalent bonding. The ensuing lattice expansion couples selfconsistently with the proton off-centering, thus explaining both the giant isotope effect, and its close connection with geometrical effects.Comment: 4 two-column pages, 4 figure

Interface effects in ferroelectric PbTiO3_3 ultrathin films on a paraelectric substrate

Interface effects on the ferroelectric behavior of PbTiO$_3$ ultrathin films deposited on SrTiO$_3$ substrate are investigated using an interatomic potential approach with parameters fitted to first-principles calculations. We find that the correlation of atomic displacements across the film/substrate interface is crucial for the stabilization of the ferroelectric state in films a few unit-cells thick. We show that the minimum film thickness for the appearance of a spontaneous polarized domain state is not an intrinsic property of the ferroelectric film but depends on the polarizability of the paraelectric substrate. We also observe that the substrate displays an induced polarization with an unusual oscillatory behavior.Comment: 4 page

Surface reconstruction and ferroelectricity in PbTiO3_3 thin films

Surface and ferroelectric properties of PbTiO$_3$ thin films are investigated using an interatomic potential approach with parameters computed from first-principles calculations. We show that a model developed for the bulk describes properly the surface properties of PbTiO$_3$. In particular, the antiferrodistortive surface reconstruction, recently observed from X-ray scattering, is correctly reproduced as a result of the change in the balance of long-range Coulombic and short-range interactions at the surface. The effects of the surface reconstruction on the ferroelectric properties of ultrathin films are investigated. Under the imposed open-circuit electrical boundary conditions, the model gives a critical thickness for ferroelectricity of 4 unit cells. The surface layer, which forms the antiferrodistortive reconstruction, participates in the ferroelectricity. A decrease in the tetragonality of the films leads to the stabilization of a phase with non-vanishing in-plane polarization. A peculiar effect of the surface reconstruction on the in-plane polarization profile is found.Comment: 6 pages, 5 figure

Asymmetric distribution of primary cilia allocates satellite cells for self-renewal

Regeneration of vertebrate skeletal muscles requires satellite cells, a population of stem cells that are quiescent in normal conditions and divide, differentiate, and self-renew upon activation triggered by exercise, injury, and degenerative diseases. Satellite cell self-renewal is essential for long-term tissue homeostasis, and previous work has identified a number of external cues that control this process. However, little is known of the possible intrinsic control mechanisms of satellite cell self-renewal. Here, we show that quiescent satellite cells harbor a primary cilium, which is rapidly disassembled upon entry into the cell cycle. Contrasting with a commonly accepted belief, cilia reassembly does not occur uniformly in cells exiting the cell cycle. We found that primary cilia reassemble preferentially in cells committed to self-renew, and disruption of cilia reassembly causes a specific deficit in self-renewing satellite cells. These observations indicate that primary cilia provide an intrinsic cue essential for satellite cell self-renewal

Quantization-based new integration methods for stiff ordinary differential equations

In this paper we introduce new classes of numerical ordinary differential equation (ODE) solvers that base their internal discretization method on state quantization instead of time slicing. These solvers have been coined quantized state system (QSS) simulators. The primary result of the research described in this article is a first-order accurate QSS-based stiff system solver, called the backward QSS (BQSS). The numerical properties of this new algorithm are discussed, and it is shown that this algorithm exhibits properties that make it a potentially attractive alternative to the classical numerical ODE solvers. Some simulation examples illustrate the advantages of this method. As a collateral result, a first-order accurate QSS-based solver designed for solving marginally stable systems is briefly outlined as well. This new method, called the centered QSS (CQSS), is successfully applied to a challenging benchmark problem describing a high-order system that is simultaneously stiff and marginally stable. However, the primary emphasis of this article is on the BQSS method, that is, on a stiff system solver based on state quantization.Fil: Migoni, Gustavo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas. Universidad Nacional de Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas; ArgentinaFil: Kofman, Ernesto Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas. Universidad Nacional de Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas; ArgentinaFil: Cellier, François. Eidgenössische Technische Hochschule Zürich; Suiz

Sequential Extraction Analysis of Arsenic in Soil Samples Collected in an Agricultural Area of Brindisi, Apulia (Italy), in the Proximity of a Coal-Burning Power Plant

none4openDanilo Migoni; Paride Papadia; Francesco Cannito; Francesco Paolo FanizziMigoni, Danilo; Papadia, Paride; Cannito, Francesco; Fanizzi, Francesco Paol

Expanding the coverage of ecosystem services in life cycle assessment: an interdisciplinary venture

To contribute to the body of knowledge aiming at a better coverage of ecosystem service assessment in LCA studies, this thesis dives into the challenges of incorporating existing ecosystem service methods within the impact assessment phase of the conventional LCA framework. Through this thesis, we present an overview of ecosystem service categories that could represent an optimal coverage for their inclusion in LCA, and provide a clear example on how to overcome the challenges of characterizing key environmental impacts that are otherwise missing or misrepresented in LCA results and that influence the quality and supply of ecosystem services. We demonstrate the approach proposed with the development of readily applicable CFs that will allow future LCA studies to account for land use impacts on pollinator abundance, and provide further evidence on the benefits of interdisciplinary collaboration as a way to strengthen our capacity to estimate anthropogenic impacts, with the use of expert elicitation methods as a valuable tool to fill in key data gaps. Lastly, we recommend to continue efforts towards an overarching archetype classification that can facilitate the inclusion of multiple biogeographical and socio-economic factors for the identification of representative patterns, and provide input across multiple impact categories at relevant spatial scales.Conservation Biolog

The role of Sonic Hedgehog signalling in satellite cell-mediated myogenesis

Adult skeletal muscle regeneration depends on the existence of tissue-specifc stem cells known as satellite cells. Satellite cells are found in a quiescent state in homeostatic conditions but become activated, re-enter the cell cycle, proliferate and differentiate or self-renew in response to muscle injury, exercise or disease. These events are tightly regulated by intrinsic and extrinsic cues, including well-characterised embryonic signalling cascades. The Sonic Hedgehog (Shh) signalling pathway has multiple roles in tissue patterning, cell fate determination, cell survival and proliferation in the embryo. Previous studies have shown that during embryonic myogenesis, Shh signalling controls the specification, migration and proliferation of muscle progenitor cells, as well as muscle patterning by the regulation of genes encoding basement membrane proteins. As the myogenic program carried out by satellite cells recapitulates, to a certain extent, embryonic myogenesis, I hypothesised that Shh signalling controls satellite cell activity in a manner reminiscent to its effect on muscle progenitor cells in the embryo. In this study, through a combination of ex vivo and in vivo approaches, I showed that, although quiescent satellite cells are refractory to Shh signals, activated satellite cells respond to Shh signalling. Shh response persists during the expansion phase and declines as satellite cells enter differentiation. Through the use of pharmacological agonists and antagonists of Shh signalling, as well as of an inducible conditional knockout mouse line of the Smoothened receptor in satellite cells, I demonstrated that Shh signalling contributes to satellite cell proliferation ex vivo and in vivo and to muscle regeneration following injury. Analysis of cell cycle dynamics showed that Shh signalling promotes the entry of satellite cells into the cell cycle and their progression through G1/S phase. Thus, the present study demonstrates that Shh signalling is required for adult skeletal muscle regeneration and provides novel insights into the role of Shh signalling in the control of satellite cell progression through the cell cycle and through myogenesis

Stress in aggressive dogs towards people: behavioral analysis during consultation

L’aggressività canina, soprattutto quella rivolta alle persone, è uno dei più gravi problemi comportamentali riferiti ai comportamentalisti. Lo scopo di questo studio è stato quello di analizzare il comportamento di cani aggressivi verso le persone durante la consulenza clinica e di confrontarlo con quello di cani affetti da altre problematiche comportamentali. Per il presente studio sono stati analizzati 26 casi clinici, divisi in due gruppi. Un gruppo di cani aggressivi (AG), costituito da 13 cani aggressivi nei confronti delle persone, ed un gruppo di cani non aggressivi (NAG), formato da 13 soggetti con altri problemi comportamentali. Il gruppo AG è stato ulteriormente diviso in altri due sottogruppi: il gruppo dei cani aggressivi verso persone estranee (AGS; n=6) ed un gruppo di cani aggressivi verso persone familiari (AGF; n=7). Tutti i cani sono stati sottoposti a consulenza comportamentale che è stata videoregistrata per essere in seguito analizzata in modo da misurare la durata (in secondi) dei comportamenti sociali e non sociali. Di ogni videoregistrazione sono stati esaminati 3 periodi per un totale di 30 minuti: T1 da 0 a 10 minuti, T2 da 25 a 35 minuti e T3 da 50 a 60 minuti. Confrontando i comportamenti emessi nei tre periodi considerati, una differenza statisticamente significativa è stata rinvenuta solo per il comportamento esplorativo: in entrambi i gruppi, AG e NAG, questo comportamento è stato manifestato maggiormente in T1 che in T2 e T3. Una differenza statisticamente significativa è emersa tra i gruppi per quanto riguarda la quantità totale dei comportamenti di stress (SB) durante i 3 periodi, con i cani del gruppo AG che mostravano un maggior livello di stress rispetto a NAG. Un’altra differenza statisticamente significativa è quella rinvenuta a carico di due comportamenti sociali: la ricerca delle attenzioni del proprietario (AG vs NAG, U=45,55; p=0,044) ed annusare il proprietario (AG vs NAG; U=42,5; p=0,029). In confronto a NAG, i cani del gruppo AGS hanno mostrato una più prolungata ricerca delle attenzioni del proprietario (U=9,500; p=0,003), l’annusare il proprietario (U=13.000; p=0.011) e la prossimità al proprietario (U=9,000; p=0,009). I cani del gruppo AGF hanno inoltre mostrato un livello più alto di comportamenti di stress (U=21,000; p=0,052), una maggior durata dell’autogrooming (U=20,000; p=0,046) e di ricerca di attenzioni dal proprietario (U=23,500; p=0,032) in confronto al gruppo NAG. In conclusione, un’attenta osservazione del comportamento dei cani durante la consulenza può fornire un addizionale utile supporto nel processo diagnostico e conseguentemente nella valutazione del rischio e nella prescrizione della terapia. Inoltre, questi risultati suggeriscono che i cani aggressivi verso le persone dovrebbero essere trattati non solo per la loro pericolosità ma anche per l’impatto che lo stress e gli aspetti emozionali del problema possono avere sul benessere dell’animale. È perciò importante che questo problema sia affrontato con un trattamento rapido ed efficace, farmacologico e/o comportamentale, e con un’intensa collaborazione tra comportamentalisti ed istruttori cinofili.Canine aggression, especially directed toward people, is one of the most severe behavioral problem referred to specialist clinics. The aim of this study was to analyze the behavior of aggressive dogs toward people in the clinic and to compare it with the behavior of dogs affected by other behavioral disorders. For the present study 26 cases were analyzed, divided into 2 groups: the aggression group (AG) consisted of 13 dogs with aggression toward people and the non-aggression group (NAG) included 13 subjects with behavioral problems other than aggression toward people. The AG group was further divided into dogs that were aggressive toward strangers (AGS; n=6), and dogs that were aggressive toward familiar people (AGF; n=7). All dogs were subjected to a behavioral consultation; the first consultation of each dog was videoed and then analyzed to measure the duration (in seconds) of social and non-social behaviors. Three focal periods of each video, totaling thirty minutes, were examined: T1 recorded minutes 0 to 10, T2 from 25’ to 35’, and T3 from 50’ to 60’. Comparing these three periods, a statistically significant difference was found only for exploratory behavior; for both AG (χ2=14.00; p=0.001) and NAG (χ2=10.51; p=0.005), exploratory behavior was higher during T1 than during T2 and T3. A statistically significant difference was found between groups for the total amount of stress behavior (SB) during the three periods, with AG showing higher amounts than NAG (U=39.5; p=0.019). Statistically significant differences were found for the total amount of two social behaviors: attention seeking from the owner (AG vs NAG, U=45.55; p=0.044) and sniffing the owner (AG vs NAG; U=42.5; p=0.029). Compared with the NAG group, the AGS dogs displayed significantly longer durations of: attention-seeking from the owner (U=9.500; p=0.003), sniffing the owner (U=13.000; p=0.011), and primary proximity to the owner (U=9.000; p=0.009). AGF dogs showed a higher level of behavioral signs of stress (U=21.000; p=0.052), a longer duration of autogrooming (U=20.000; p=0.046), and a higher attention-seeking from the owner (U=23.500; p=0.032), compared to NAG. Interesting results emerged when comparing dogs that were aggressive toward strangers or toward familiar people. These findings suggest that through the systematic analysis of dog behavior during a consultation it is possible to observe different patterns of dogs’ behavior according to the kind of diagnosis. Namely, during the behavioral consultations, dogs that are aggressive towards strangers showed more seeking behaviors towards the owners, whilst dogs that were aggressive towards family members showed more signs of stress. In conclusion, a careful observation of the behavior of dogs during a consultation could provide additional valuable support in the diagnostic process, and consequently in the risk assessment and in prescribing the therapy to dogs aggressive towards people. Moreover these results suggest that the aggressive dogs toward people should be treated not only for their dangerousness, but also for the impact that underlying stress and emotional aspects of the problem might have on the welfare of the dog, and highlighting how urgent its treatment should be. It is therefore important that this problem is treated with rapid and effective treatment, both pharmacological and/or behavioral, and with an extensive collaboration between veterinary behaviorists and dog trainer