1,304 research outputs found

    Measuring the integrated effectiveness of regional development : directions for regional government

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    Purpose: The purpose of the study is to identify the proper economic tools to evaluate the effectiveness and efficiency of a regional development policy. Design/Methodology/Approach: The proposed methodology consists of three stages. At the first stage, the indicators are analyzed, allowing pointing the level of particular development dimensions in the self government strategy. At the second stage, indicators characterizing the efficiency of Opolskie Regional Operating Programme (OROP) and Development Strategy of Opole Voivodeship are examined. The third final stage is the analysis of the integrated effectiveness of regional development policy. The research methodology is based on the use of the following methods: desk research, the method of grouping statistical data, and the method of effectiveness analysis. Findings: The proposed methodology let us to find the need of redefining the tool enabling the measure of the degree of imbalance as the result of leading the regional development policy, as well as the uneven development potentials. Practical Implications: The authors purpose a new approach to the regional development policy by defining the complementary tools for regional self government evaluation. Originality/Value: The authors propose the new approach to the regional development policy programming, especially by redefining regional needs included into regional strategies.peer-reviewe

    Design, development and validation of iron-based composites for biodegradable implant applications

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    "Thèse en cotutelle : Doctorat en génie des matériaux et de la métallurgie, Université Laval, Québec, Canada, Philosophiæ doctor (Ph. D.) et Politecnico di Milano, Milano, Italie."Récemment, le Fe et ses alliages ont montré leur potentiel en tant que matériaux dégradables pour des applications biomédicales. Néanmoins, la vitesse de corrosion lente limite leurs performances dans certaines situations. Les matériaux composites à matrice de fer représentent une approche possible, non seulement pour améliorer leurs propriétés mécaniques, mais aussi pour accélérer et ajuster la vitesse de corrosion dans un environnement physiologique. Dans ce travail, des composites à base de Fe renforcés par des particules Mg2Si ont été proposés. Les poudres initiales ont été préparées par différentes combinaisons de procédés de mélange et de broyage, et finalement consolidées par laminage à chaud. L'influence de la microstructure sur les propriétés mécaniques et le comportement à la corrosion de Fe/Mg2Si a été étudiée. Les échantillons contenant des particules Mg2Si plus petites présentaient une distribution plus homogène du renforcement. Le rendement et l’état limite ultime à la traction ont augmenté par rapport à ceux du Fe pur. La présence des particules de renforcement a joué un rôle crucial dans la susceptibilité à l'attaque de corrosion localisée dans les composites à base de Fe. L'initiation de la corrosion et son développement ont été systématiquement suivis pour étudier le mécanisme de corrosion. L'importance des particules de Mg2Si dans le déclenchement des processus de corrosion a été expliquée. Des mesures électrochimiques et des tests d'immersion statique ont indiqué que l'ajout de Mg2Si pourrait augmenter le taux de corrosion du Fe. Il a été constaté que la taille et la distribution des particules de renfort jouaient un rôle crucial à l'uniformité de l'attaque de corrosion. Après, une série de tests d'immersion à différents intervalles d'exposition (20, 50 et 100 jours) à la solution modifiée de Hanks a été réalisée à fin d’évaluer le comportement de dégradation des composites Fe/Mg2Si et Fe pur préparés par différentes techniques de métallurgie des poudres. Les résultats ont révélé l’importance du Mg2Si dans la composition et la stabilité des films protecteurs formés lors des expériences de corrosion statique. Les composites Fe/Mg2Si présentaient des taux de dégradation plus élevés que le Fe pur à toutes les étapes du test d'immersion. Les taux de dégradation à des intervalles d'exposition distincts dépendaient fortement de la composition et de la stabilité des films protecteurs d'oxyde, d'hydroxyde, de carbonate et de phosphate formés sur les surfaces dégradées. La libération d'ions Fe dans la solution aux stades ultérieurs de l'expérience était limitée en raison de l'effet de barrière dû au dépôt insoluble. Cette étude fondamentale a servi de base aux processus de formation de film protecteur dans la solution de Hanks modifiée, permettant une identification détaillée de leurs caractéristiques.Fe-based alloys have shown a potential as a degradable material for biomedical applications. Nevertheless, the slow corrosion rate limits their performance as a biodegradable implant. One approach to control and modify their corrosion properties is the reinforcement addition, to create metal matrix composites in which the second phase is aimed at tuning not only the mechanical properties but also the corrosion mode and rate in a physiological environment. This thesis presents an original and thorough contribution on a very pertinent topic, the design, development, and validation of a new Fe/Mg2Si composites prepared powder metallurgy. The initial powders were prepared by different combinations of mixing and high energy ball milling processes and finally consolidated by hot rolling. Mechanical properties, microstructural features, as well as the corrosion performance, were extensively investigated in relation to the reinforcement size and distribution. The composites made of small size reinforcement particles showed a general increase in tensile strength. For instance, high energy ball milled samples exhibited better tensile performances (YS = 523 MPa, UTS = 630 MPa) while having the lower ductility (around 4%). A fundamental understanding of corrosion initiation, protective film formation, and growth on Fe-based materials and leads to a design of smarter and surface responsive biomaterials with modulable degradation rates, at distinct stages of the corrosion process. Here, the corrosion performance of Fe/Mg2Si composites varied with the reinforcement size and distribution. The predominant localized pitting corrosion in Fe/Mg2Si prepared by mixing was replaced by a more uniform pattern found in samples produced by mechanical milling. Further, it was found that Mg2Si plays a significant role in the composition and stability of the protective films formed during the static corrosion experiments. Fe/Mg2Si showed a higher corrosion rate compared to that of pure Fe at all stages of the corrosion experiment (1, 10, 20, 50 and 100 days). Moreover, the final degradation products varied with the substrate chemical composition and microstructure. In case of pure Fe, low solubility (Fe3(PO4)2) covered the entire surface, while Fe/Mg2Si exhibited the presence of carbonates at the latest stages of the test. The details about the degradation behaviour during long-term exposure times to the physiological environment highlighted in this work add a new knowledge on corrosion mechanism of degradable implant materials. In particular, the ability to tune mechanical and corrosion behavior of the composites as a function of reinforcement properties and manufacturing method was experimentally verified, highlighting the microstructure-corrosion property relationship.I biomateriali in ferro puro e in leghe a base di ferro presentano una combinazione interessante di proprietà meccaniche, elettrochimiche e biologiche; per questo motivo, questa classe di materiali metallici possono trovare utilizzo in applicazioni di tipo impiantistico biomedicale. Malgrado ciò, nonostante le sue soddisfacenti proprietà meccaniche, questo elemento impiegato allo stato puro mostra un inconveniente rilevante - un basso tasso di degradazione. L’oggetto di questa tesi è lo studio di un nuovo gruppo di materiali biodegradabili compositi a matrice ferrosa (Fe/Mg2Si), in cui il Fe costituisce la matrice e il Mg2Si è impiegato come rinforzo; questi materiali sono stati sviluppati con tecniche di metallurgia delle polveri, e presentano un, alta resistenza meccanica come caratteristica principale. Le polveri che costituiscono i materiali di partenza sono stati preparati con diverse combinazioni di procedure oltre al semplice mescolamento e/o high energy ball milling (macinatura in mulino a sfere a alta energia). Tutte le formulazioni preparate sono state compattate attraverso laminazione a caldo. Le proprietà meccaniche, le caratteristiche microstrutturali, la composizione delle fasi e le prestazioni in termini di corrosione sono state studiate dettagliatamente, in relazione alla dimensione delle particelle di rinforzo e della loro distribuzione. Lavori precedenti hanno confermato l’efficacia dell’aggiunta di una seconda fase, soprattutto se finemente dispersa, per aumentare il tasso di degradazione di materiali metallici per applicazioni biomedicali a base Fe: gli esperimenti condotti in questo lavoro hanno confermato che i compositi Fe/Mg2Si hanno mostrato, rispetto al Fe puro che compone la matrice, non solo una resistenza meccanica più elevata, ma anche un tasso di degradazione più alto negli esperimenti di laboratorio in vitro. Infine, i materiali ottenuti tramite high energy ball milling, presentano una resistenza alla trazione migliore (carico di snervamento= 523 MPa, resistenza alla trazione = 630 MPa), ma contemporaneamente una ridotta duttilità (circa 4%). Una attenzione particolare è stata posta nello studio degli effetti della presenza di Mg2Si sui meccanismi di corrosione.Tutti i compositi studiati hanno mostrato un tasso di degradazione più elevato rispetto alla matrice fabbricata con la stessa procedura; inoltre, la formazione del film di prodotti di degradazione sulla superficie del materiale cambiava in maniera rilevante in funzione della composizione chimica del substrato e della sua microstruttura. Nel caso del Fe puro, cristalli isolati di vivianite (Fe3(PO4)2) erano presenti su tutta la superficie, mentre carbonati di Fe si formavano principalmente sulla superficie dei compositi, specialmente negli ultimi stadi del processo di degradazione

    How age of bilingual exposure can change the neural systems for language in the developing brain: A functional near infrared spectroscopy investigation of syntactic processing in monolingual and bilingual children

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    AbstractIs the developing bilingual brain fundamentally similar to the monolingual brain (e.g., neural resources supporting language and cognition)? Or, does early-life bilingual language experience change the brain? If so, how does age of first bilingual exposure impact neural activation for language?We compared how typically-developing bilingual and monolingual children (ages 7–10) and adults recruit brain areas during sentence processing using functional Near Infrared Spectroscopy (fNIRS) brain imaging. Bilingual participants included early-exposed (bilingual exposure from birth) and later-exposed individuals (bilingual exposure between ages 4–6).Both bilingual children and adults showed greater neural activation in left-hemisphere classic language areas, and additionally, right-hemisphere homologues (Right Superior Temporal Gyrus, Right Inferior Frontal Gyrus). However, important differences were observed between early-exposed and later-exposed bilinguals in their earliest-exposed language. Early bilingual exposure imparts fundamental changes to classic language areas instead of alterations to brain regions governing higher cognitive executive functions. However, age of first bilingual exposure does matter. Later-exposed bilinguals showed greater recruitment of the prefrontal cortex relative to early-exposed bilinguals and monolinguals.The findings provide fascinating insight into the neural resources that facilitate bilingual language use and are discussed in terms of how early-life language experiences can modify the neural systems underlying human language processing

    Rapid, learning-induced inhibitory synaptogenesis in murine barrel field

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    The structure of neurons changes during development and in response to injury or alteration in sensory experience. Changes occur in the number, shape, and dimensions of dendritic spines together with their synapses. However, precise data on these changes in response to learning are sparse. Here, we show using quantitative transmission electron microscopy that a simple form of learning involving mystacial vibrissae results in approximately 70% increase in the density of inhibitory synapses on spines of neurons located in layer IV barrels that represent the stimulated vibrissae. The spines contain one asymmetrical (excitatory) and one symmetrical (inhibitory) synapse (double-synapse spines), and their density increases threefold as a result of learning with no apparent change in the density of asymmetrical synapses. This effect seems to be specific for learning because pseudoconditioning (in which the conditioned and unconditioned stimuli are delivered at random) does not lead to the enhancement of symmetrical synapses but instead results in an upregulation of asymmetrical synapses on spines. Symmetrical synapses of cells located in barrels receiving the conditioned stimulus also show a greater concentration of GABA in their presynaptic terminals. These results indicate that the immediate effect of classical conditioning in the "conditioned" barrels is rapid, pronounced, and inhibitory

    The complex genetic basis of simple behavior

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    Genetic approaches to dissecting complex traits in animal models increasingly use transcript levels as a molecular phenotype and as validation for predictions of gene function. A recent study in BMC Biology using these approaches shows the complexity of the genetic contribution to aggressive behavior in Drosophila

    Management effects on carbon distribution in soil aggregates and its consequences on water repellency and mechanical strength

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    The purpose of this study was to investigate the physico-chemical heterogeneity of structured soils by analysing bulk soil, soil aggregates and homogenized material from arable soils (conservation and conventional tillage) in comparison to grassland soils. The organic carbon distribution of the investigated soils showed not only higher contents in the topsoil, but also smaller aggregates contained more Corg after segregation by dry sieving. The determination of carbon using δ13C identified that in the smallest fraction mostly fresh deposited organic carbon was accumulated. After Na-pyrophosphate percolation the smallest aggregate were the most influenced by percolation and most of the organic carbon was lost. The determination of organic carbon distribution and the δ13C signal within soil aggregates have shown only a slight tendency of higher Corg accumulation in the exterior aggregate region in comparison to the interior regions. Most investigated soil aggregates showed higher amounts of hydrophilic groups in the exterior regions of aggregates than in the interior regions. In addition K, Fe and Al have shown reduced contents in exterior regions in comparison to the interior regions, in contrast to the Na enrichment on the aggregate surface. The tensile strength of air dry aggregates was affected by the moisture content, depth of the soil and the size of the aggregates. The largest differences considering soil management were found between grassland and arable soil, while the differences between conventional and conservation tillage systems were less pronounced
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