953 resultados para carbon isotope of individual lipid


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In the last decades, the increasing significance of “projectivization” (Lundin & Steinthórsson, 2003) has stimulated considerable interest in project-based organizations as new economic actors able to introduce a new logic of organizing work and weakening boundaries in favour of networks of collaborations. In these contexts, work is often delegated to project teams. Deciding whom to put on a project team is one of the biggest challenges faced by a project manager; in particular which characteristics rely on to compose and match effective teams. We address this issue, focusing on the individual flexibility (Raudsepp, 1990), as team composition variable that affects project team performance. Thus, the research question investigated is: Is it better to compose project teams with flexible team members or not flexible project team members to achieve higher levels of project performance? The temporary nature of PBOs involves that after achieving the purpose for which team members are enrolled, they are disbanded but their relationships remain, allowing them to be involved in future projects (Starkey, Barnatt & Tempest, 2000). Pre-existing relationships together with the current relationships create a network of relationships that yields some implications for project teams as well as for team members. We address this issue, exploring the following research question: To what extent is the individual flexibility influenced by the network structure? The conceptual framework is used to articulate the research questions investigated with respect to the Television drama serials production. Their project-team organizing combined with their capacity to dissolve and recreate over time make it an interesting field to develop. We contribute to the organizational literature, providing a clear operationalization of individual flexibility construct and its role on affecting project performance. Second, we contribute to the organizational network literature addressing the effects yielded by the network structure-structural holes and network closure- on the individual flexibility.

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In modern farm systems the economic interests make reducing the risks related to transport practice an important goal. An increasing attention is directed to the welfare of animals in transit, also considering the new existing facilities. In recent years the results coming from the study of animal farm behaviour were used as tool to assess the welfare. In this thesis were analyzed behavioural patterns, jointly with blood variables, to evaluate the stress response of piglets and young bulls during transport. Since the animal behaviour could be different between individuals and these differences can affect animal responses to aversive situations, the individual behavioural characteristics were taken in account. Regarding young bulls, selected to genetic evaluation, the individual behaviour was investigated before, during and after transport, while for piglets was adopted a tested methodology classification and behavioural tests to observe their coping characteristics. The aim of this thesis was to analyse the behavioural and physiological response of young bulls and piglets to transport practice and to investigate if coping characteristics may affect how piglets cope with aversive situations. The thesis is composed by four experimental studies. The first one aims to identify the best existent methodology classification of piglets coping style between those that were credited in literature. The second one investigated the differences in response to novel situations of piglets with different coping styles. The last studies evaluated the stress response of piglets and young bulls to road transportation. The results obtained show that transport did not affect the behaviour and homeostasis of young animals which respond in a different way from adults. However the understanding of individual behavioural characteristic and the use of behavioural patterns, in addition to blood analyses, need to be more investigated in order to be useful tools to assess the animal response in aversive situation.

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In my dissertation I investigated the influence of behavioral variation between and within ant colonies on group performance. In particular, I analyzed how evolution shapes behavior in response to ecological conditions, and whether within-group diversity improves productivity as suggested by theory. Our field and laboratory experiments showed that behavioral diverse groups are more productive. Different aggression levels within colonies were beneficial under competitive field situations, whereas diversity in brood care and exploratory behavior were favored in non-competitive laboratory situations. We then examined whether population density and social parasite presence shape aggression through phenotypic plasticity and/or natural selection. The importance of selection was indicated by the absence of density or parasite effects on aggression in a field manipulation. Indeed, more aggressive colonies fared better under high density and during parasite attack. When analyzing the proximate causes of individual behavioral variation, ovarian development was shown to be linked to division of labor and aggressiveness. Finally, our studies show that differences in the collective behavior can be linked to immune defense and productivity. My dissertation demonstrates that behavioral variation should be studied on multiple scales and when possible combined with physiological analyses to better understand the evolution of animal personalities in social groups.rn

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Das in dieser Arbeit vorgestellte Experiment zur Messung des magnetischen Moments des Protons basiert auf der Messung des Verhältnisses von Zyklotronfrequenz und Larmorfrequenz eines einzelnen, in einer kryogenen Doppel-Penning Falle gespeicherten Protons. In dieser Arbeit konnten erstmalig zwei der drei Bewegungsfrequenzen des Protons gleichzeitig im thermischen Gleichgewicht mit entsprechenden hochsensitiven Nachweissystemen nicht-destruktiv detektiert werden, wodurch die Messzeit zur Bestimmung der Zyklotronfrequenz halbiert werden konnte. Ferner wurden im Rahmen dieser Arbeit erstmalig einzelne Spin-Übergänge eines einzelnen Protons detektiert, wodurch die Bestimmung der Larmorfrequenz ermöglicht wird. Mithilfe des kontinuierlichen Stern-Gerlach Effekts wird durch eine sogenannte magnetische Flasche das magnetische Moment an die axiale Bewegungsmode des Protons gekoppelt. Eine Änderung des Spinzustands verursacht folglich einen Frequenzsprung der axialen Bewegungsfrequenz, welche nicht-destruktiv gemessen werden kann. Erschwert wird die Detektion des Spinzustands dadurch, dass die axiale Frequenz nicht nur vom Spinmoment, sondern auch vom Bahnmoment abhängt. Die große experimentelle Herausforderung besteht also in der Verhinderung von Energieschwankungen in den radialen Bewegungsmoden, um die Detektierbarkeit von Spin-Übergängen zu gewährleisten. Durch systematische Studien zur Stabilität der axialen Frequenz sowie einer kompletten Überarbeitung des experimentellen Aufbaus, konnte dieses Ziel erreicht werden. Erstmalig kann der Spinzustand eines einzelnen Protons mit hoher Zuverlässigkeit bestimmt werden. Somit stellt diese Arbeit einen entscheidenden Schritt auf dem Weg zu einer hochpräzisen Messung des magnetischen Moments des Protons dar.

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The accretionary shells of bivalve mollusks can provide environmental information, such as water temperature, precipitation, freshwater fluxes, primary productivity and anthropogenic activities in the form of variable growth rates and variable geochemical properties, such as stable oxygen and carbon isotopes. However, paleoenvironmental reconstructions are constrained by uncertainties about isotopic equilibrium fractionation during shell formation, which is generally acknowledged as a reasonable assumption for bivalves, but it has been disputed in several species. Furthermore, the variation in shell growth rates is accepted to rely on multiple environmental variables, such as temperature, food availability and salinity, but can differ from species to species. Therefore, it is necessary to perform species-specific calibration studies for both isotope proxies and shell growth rates before they can be used with confidence for environmental interpretations of the past. Accordingly, the principal objective of this Ph.D research is to examine the reliability of selected bivalve species, the long-lived Eurhomalea exalbida (Dillwyn), the short-lived and fast growing species Paphia undulata (Born 1778), and the freshwater mussel Margaritifera falcata (Gould 1850), as paleoenvironmental proxy archives.rnThe first part is focused on δ18Oshell and shell growth history of live-collected E. exalbida from the Falkland Islands. The most remarkable finding, however, is that E. exalbida formed its shell with an offset of -0.48‰ to -1.91‰ from the expected oxygen isotopic equilibrium with the ambient water. If this remained unnoticed, paleotemperature estimates would overestimate actual water temperatures by 2.1-8.3°C. With increasing ontogenetic age, the discrepancy between measured and reconstructed temperatures increased exponentially, irrespective of the seasonally varying shell growth rates. This study clearly demonstrates that, when the disequilibrium fractionation effect is taken into account, E. exalbida can serve as a high-resolution paleoclimate archive for the southern South America. The species therefore provides quantifiable temperature estimates, which yields new insights into long-term paleoclimate dynamics for mid to high latitudes on the southern hemisphere.rnThe stable carbon isotope of biogenic carbonates is generally considered to be useful for reconstruction of seawater dissolved inorganic carbon. The δ13Cshell composition of E. exalbida was therefore, investigated in the second part of this study. This chapter focuses on inter-annual and intra-annual variations in δ13Cshell. Environmental records in δ13Cshell are found to be strongly obscured by changes in shell growth rates, even if removing the ontogenetic decreasing trend. This suggests that δ13Cshell in E. exalbida may not be useful as an environmental proxy, but a potential tool for ecological investigations. rnIn addition to long-lived bivalve species, short-lived species that secrete their shells extremely fast, can also be useful for environmental reconstructions, especially as a high-resolution recorder. Therefore, P. undulata from Daya Bay, South China Sea was utilized in Chapter 4 to evaluate and establish a potential proxy archive for past variations of the East Asian monsoon on shorter time-scales. The δ18Oshell can provide qualitative estimates of the amount of monsoonal rain and terrestrial runoff and the δ13Cshell likely reflect the relative amount of isotopically light terrestrial carbon that reaches the ocean during the summer monsoon season. Therefore, shells of P. undulata can provide serviceable proxy archives to reconstruct the frequency of exceptional summer monsoons in the past. The relative strength of monsoon-related precipitation and associated changes in ocean salinity and the δ13C ratios of the dissolved inorganic carbon signature (δ13CDIC) can be estimated from the δ18Oshell and δ13Cshell values as well as shell growth patterns. rnIn the final part, the freshwater pearl shell M. falcata from four rivers in British Columbia, Canada was preliminarily studied concerning the lifespans and the shell growth rates. Two groups separated by the Georgia Strait can be clearly distinguished. Specimens from the western group exhibit a shorter lifespan, while the eastern group live longer. Moreover, the average lifespan seems to decrease from south to north. The computed growth equations from the eastern and western groups differ as well. The western group exhibits a lower growth rate, while bivalves from the eastern group grow faster. The land use history seems to be responsible for the differences in lifespans of the specimens from the two groups. Differences in growth rate may be induced by differences in water temperature or nutrient input also related to the land use activities.

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Cognitive task performance differs considerably between individuals. Besides cognitive capacities, attention might be a source of such differences. The individual's EEG alpha frequency (IAF) is a putative marker of the subject's state of arousal and attention, and was found to be associated with task performance and cognitive capacities. However, little is known about the metabolic substrate (i.e. the network) underlying IAF. Here we aimed to identify this network. Correlation of IAF with regional Cerebral Blood Flow (rCBF) in fifteen young healthy subjects revealed a network of brain areas that are associated with the modulation of attention and preparedness for external input, which are relevant for task execution. We hypothesize that subjects with higher IAF have pre-activated task-relevant networks and thus are both more efficient in the task-execution, and show a reduced fMRI-BOLD response to the stimulus, not because the absolute amount of activation is smaller, but because the additional activation by processing of external input is limited due to the higher baseline.

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the modern joint protection (JP) concept for people with rheumatoid arthritis (RA) is an active coping strategy to improve daily tasks and role performance by changing working methods and using assistive devices. Effective group JP education includes psycho-educational interventions. The Pictorial Representation of Illness and Self Measure (PRISM) is an interactive hands-on-tool, assessing (a) the individual's perceived burden of illness and (b) relevant individual resources. Both issues are important for intrinsic motivation to take action and change behaviour. This study compared individual conventional JP education (C-JP) with PRISM-based JP education (PRISM-JP).

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The safety and efficacy of thrombolysis in cervical artery dissection (CAD) are controversial. The aim of this meta-analysis was to pool all individual patient data and provide a valid estimate of safety and outcome of thrombolysis in CAD.

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The efficacy of durable polymer drug-eluting stents (DES) is delivered at the expense of delayed healing of the stented vessel. Biodegradable polymer DES aim to avoid this shortcoming and may potentially improve long-term clinical outcomes, with benefit expected to accrue over time. We sought to compare long-term outcomes in patients treated with biodegradable polymer DES vs. durable polymer sirolimus-eluting stents (SES).

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Joint protection (JP) education for people with rheumatoid arthritis (RA) is effective when applying psycho-educational teaching strategies. The Pictorial Representation of Illness and Self Measure (PRISM) was used to identify relevant JP education goals and life aspects, both supporting motivation and behaviour change. The objective of this study was to compare the effects of individual JP education, PRISM-based (PRISM-JP) vs. conventional (C-JP), in people with rheumatoid arthritis (RA).