6 resultados para Pattern of Use
em AMS Tesi di Dottorato - Alm@DL - Università di Bologna
Resumo:
Customer satisfaction has been traditionally studied and measured regardless of the time elapsed since the purchase. Some studies have recently reopened the debate about the temporal pattern of satisfaction. This research aims to explain why “how you evaluate a service depends on when you evaluate it” on the basis of the theoretical framework proposed by Construal-Level Theory (CLT). Although an empirical investigation is still lacking, the literature does not deny that CLT can be applied also with regard to past events. Moreover, some studies support the idea that satisfaction is a good predictor of future intentions, while others do not. On the basis of CLT, we argue that these inconsistent results are due to the different construal levels of the information pertaining to retrospective and prospective evaluations. Building on the Two-Factor Theory, we explain the persistence of certain attributes’ representations over time according to their relationship with overall performance. We present and discuss three experiments and one field study that were conducted a) to test the extensibility of CLT to past events, b) to disentangle memory and construal effects, c) to study the effect of different temporal perspective on overall satisfaction judgements, and d) to investigate the temporal shift of the determinants of customer satisfaction as a function of temporal distance.
Resumo:
The irrigation scheme Eduardo Mondlane, situated in Chókwè District - in the Southern part of the Gaza province and within the Limpopo River Basin - is the largest in the country, covering approximately 30,000 hectares of land. Built by the Portuguese colonial administration in the 1950s to exploit the agricultural potential of the area through cash-cropping, after Independence it became one of Frelimo’s flagship projects aiming at the “socialization of the countryside” and at agricultural economic development through the creation of a state farm and of several cooperatives. The failure of Frelimo’s economic reforms, several infrastructural constraints and local farmers resistance to collective forms of production led to scheme to a state of severe degradation aggravated by the floods of the year 2000. A project of technical rehabilitation initiated after the floods is currently accompanied by a strong “efficiency” discourse from the managing institution that strongly opposes the use of irrigated land for subsistence agriculture, historically a major livelihood strategy for smallfarmers, particularly for women. In fact, the area has been characterized, since the end of the XIX century, by a stable pattern of male migration towards South African mines, that has resulted in an a steady increase of women-headed households (both de jure and de facto). The relationship between land reform, agricultural development, poverty alleviation and gender equality in Southern Africa is long debated in academic literature. Within this debate, the role of agricultural activities in irrigation schemes is particularly interesting considering that, in a drought-prone area, having access to water for irrigation means increased possibilities of improving food and livelihood security, and income levels. In the case of Chókwè, local governments institutions are endorsing the development of commercial agriculture through initiatives such as partnerships with international cooperation agencies or joint-ventures with private investors. While these business models can sometimes lead to positive outcomes in terms of poverty alleviation, it is important to recognize that decentralization and neoliberal reforms occur in the context of financial and political crisis of the State that lacks the resources to efficiently manage infrastructures such as irrigation systems. This kind of institutional and economic reforms risk accelerating processes of social and economic marginalisation, including landlessness, in particular for poor rural women that mainly use irrigated land for subsistence production. The study combines an analysis of the historical and geographical context with the study of relevant literature and original fieldwork. Fieldwork was conducted between February and June 2007 (where I mainly collected secondary data, maps and statistics and conducted preliminary visit to Chókwè) and from October 2007 to March 2008. Fieldwork methodology was qualitative and used semi-structured interviews with central and local Government officials, technical experts of the irrigation scheme, civil society organisations, international NGOs, rural extensionists, and water users from the irrigation scheme, in particular those women smallfarmers members of local farmers’ associations. Thanks to the collaboration with the Union of Farmers’ Associations of Chókwè, she has been able to participate to members’ meeting, to education and training activities addressed to women farmers members of the Union and to organize a group discussion. In Chókwè irrigation scheme, women account for the 32% of water users of the familiar sector (comprising plot-holders with less than 5 hectares of land) and for just 5% of the private sector. If one considers farmers’ associations of the familiar sector (a legacy of Frelimo’s cooperatives), women are 84% of total members. However, the security given to them by the land title that they have acquired through occupation is severely endangered by the use that they make of land, that is considered as “non efficient” by the irrigation scheme authority. Due to a reduced access to marketing possibilities and to inputs, training, information and credit women, in actual fact, risk to see their right to access land and water revoked because they are not able to sustain the increasing cost of the water fee. The myth of the “efficient producer” does not take into consideration the characteristics of inequality and gender discrimination of the neo-liberal market. Expecting small-farmers, and in particular women, to be able to compete in the globalized agricultural market seems unrealistic, and can perpetuate unequal gendered access to resources such as land and water.
Resumo:
The repressor element 1-silencing transcription factor (REST) was first identified as a protein that binds to a 21-bp DNA sequence element (known as repressor element 1 (RE1)) resulting in transcriptional repression of the neural-specific genes [Chong et al., 1995; Schoenherr and Anderson, 1995]. The original proposed role for REST was that of a factor responsible for restricting neuronal gene expression to the nervous system by silencing expression of these genes in non-neuronal cells. Although it was initially thought to repress neuronal genes in non-neuronal cells, the role of REST is complex and tissue dependent. In this study I investigated any role played by REST in the induction and patterning of differentiation of SH-SY5Y human neuroblastoma cells exposed to IGF-I. and phorbol 12- myristate 13-acetate (PMA) To down-regulate REST expression we developed an antisense (AS) strategy based on the use of phosphorothioate oligonucleotides (ODNs). In order to evaluate REST mRNA levels, we developed a real-time PCR technique and REST protein levels were evaluated by western blotting. Results showed that nuclear REST is increased in SH-SY5Y neuroblastoma cells cultured in SFM and exposed to IGF-I for 2-days and it then declines in 5-day-treated cells concomitant with a progressive neurite extension. Also the phorbol ester PMA was able to increase nuclear REST levels after 3-days treatment concomitant to neuronal differentiation of neuroblastoma cells, whereas, at later stages, it is down-regulated. Supporting these data, the exposure to PKC inhibitors (GF10923X and Gö6976) and PMA (16nM) reverted the effects observed with PMA alone. REST levels were related to morphological differentiation, expression of growth coneassociated protein 43 (GAP-43; a gene not regulated by REST) and of synapsin I and βIII tubulin (genes regulated by REST), proteins involved in the early stage of neuronal development. We observed that differentiation of SH-SY5Y cells by IGF-I and PMA was accompanied by a significant increase of these neuronal markers, an effect that was concomitant with REST decrease. In order to relate the decreased REST expression with a progressive neurite extension, I investigated any possible involvement of the ubiquitin–proteasome system (UPS), a multienzymatic pathway which degrades polyubiquinated soluble cytoplasmic proteins [Pickart and Cohen, 2004]. For this purpose, SH-SY5Y cells are concomitantly exposed to PMA and the proteasome inhibitor MG132. In SH-SY5Y exposed to PMA and MG 132, we observed an inverse pattern of expression of synapsin I and β- tubulin III, two neuronal differentiation markers regulated by REST. Their cytoplasmic levels are reduced when compared to cells exposed to PMA alone, as a consequence of the increase of REST expression by proteasome inhibitor. The majority of proteasome substrates identified to date are marked for degradation by polyubiquitinylation; however, exceptions to this principle, are well documented [Hoyt and Coffino, 2004]. Interestingly, REST degradation seems to be completely ubiquitin-independent. The expression pattern of REST could be consistent with the theory that, during early neuronal differentiation induced by IGF-I and PKC, it may help to repress the expression of several genes not yet required by the differentiation program and then it declines later. Interestingly, the observation that REST expression is progressively reduced in parallel with cell proliferation seems to indicate that the role of this transcription factor could also be related to cell survival or to counteract apotosis events [Lawinger et al., 2000] although, as shown by AS-ODN experiments, it does not seem to be directly involved in cell proliferation. Therefore, the decline of REST expression is a comparatively later event during maturation of neuroroblasts in vitro. Thus, we propose that REST is regulated by growth factors, like IGF-I, and PKC activators in a time-dependent manner: it is elevated during early steps of neural induction and could contribute to down-regulate genes not yet required by the differentiation program while it declines later for the acquisition of neural phenotypes, concomitantly with a progressive neurite extension. This later decline is regulated by the proteasome system activation in an ubiquitin-indipendent way and adds more evidences to the hypothesis that REST down-regulation contributes to differentiation and arrest of proliferation of neuroblastoma cells. Finally, the glycosylation pattern of the REST protein was analysed, moving from the observation that the molecular weight calculated on REST sequence is about 116 kDa but using western blotting this transcription factor appears to have distinct apparent molecular weight (see Table 1.1): this difference could be explained by post-translational modifications of the proteins, like glycosylation. In fact recently, several studies underlined the importance of O-glycosylation in modulating transcriptional silencing, protein phosphorylation, protein degradation by proteasome and protein–protein interactions [Julenius et al., 2005; Zachara and Hart, 2006]. Deglycosilating analysis showed that REST protein in SH-SY5Y and HEK293 cells is Oglycosylated and not N-glycosylated. Moreover, using several combination of deglycosilating enzymes it is possible to hypothesize the presence of Gal-β(1-3)-GalNAc residues on the endogenous REST, while β(1-4)-linked galactose residues may be present on recombinant REST protein expressed in HEK293 cells. However, the O-glycosylation process produces an immense multiplicity of chemical structures and monosaccharides must be sequentially hydrolyzed by a series of exoglycosidase. Further experiments are needed to characterize all the post-translational modification of the transcription factor REST.
Resumo:
The Ecosystem Approach to Fisheries represents the most recent research line in the international context, showing interest both towards the whole community and toward the identification and protection of all the “critical habitats” in which marine resources complete their life cycles. Using data coming from trawl surveys performed in the Northern and Central Adriatic from 1996 to 2010, this study provides the first attempt to appraise the status of the whole demersal community. It took into account not only fishery target species but also by-catch and discharge species by the use of a suite of biological indicators both at population and multi-specific level, allowing to have a global picture of the status of the demersal system. This study underlined the decline of extremely important species for the Adriatic fishery in recent years; adverse impact on catches is expected for these species in the coming years, since also minimum values of recruits recently were recorded. Both the excessive exploitation and environmental factors affected availability of resources. Moreover both distribution and nursery areas of the most important resources were pinpointed by means of geostatistical methods. The geospatial analysis also confirmed the presence of relevant recruitment areas in the North and Central Adriatic for several commercial species, as reported in the literature. The morphological and oceanographic features, the relevant rivers inflow together with the mosaic pattern of biocenoses with different food availability affected the location of the observed relevant nursery areas.
Resumo:
A control-oriented model of a Dual Clutch Transmission was developed for real-time Hardware In the Loop (HIL) applications, to support model-based development of the DCT controller. The model is an innovative attempt to reproduce the fast dynamics of the actuation system while maintaining a step size large enough for real-time applications. The model comprehends a detailed physical description of hydraulic circuit, clutches, synchronizers and gears, and simplified vehicle and internal combustion engine sub-models. As the oil circulating in the system has a large bulk modulus, the pressure dynamics are very fast, possibly causing instability in a real-time simulation; the same challenge involves the servo valves dynamics, due to the very small masses of the moving elements. Therefore, the hydraulic circuit model has been modified and simplified without losing physical validity, in order to adapt it to the real-time simulation requirements. The results of offline simulations have been compared to on-board measurements to verify the validity of the developed model, that was then implemented in a HIL system and connected to the TCU (Transmission Control Unit). Several tests have been performed: electrical failure tests on sensors and actuators, hydraulic and mechanical failure tests on hydraulic valves, clutches and synchronizers, and application tests comprehending all the main features of the control performed by the TCU. Being based on physical laws, in every condition the model simulates a plausible reaction of the system. The first intensive use of the HIL application led to the validation of the new safety strategies implemented inside the TCU software. A test automation procedure has been developed to permit the execution of a pattern of tests without the interaction of the user; fully repeatable tests can be performed for non-regression verification, allowing the testing of new software releases in fully automatic mode.
Resumo:
Follicular lymphoma (FL) is a B cell neoplasm, composed of follicle center cells, that accounts for about 20% of all lymphomas, with the highest incidence reported in the USA and western Europe. FL has been considered a virtually incurable disease, with a high response rate alternated with frequent post-therapy relapses or progression towards more aggressive lymphomas. Due to the extreme variability in outcome, many efforts were made to predict prognosis, the need for therapy, and the likelihood of evolution. Even if clinical scores turned out to be robust and easy to use in clinical practice for patient risk stratification, marked heterogeneity in outcome remains within each group and further insights into the biology of FL are needed. The genome-wide approach underscored the pivotal role of the FL microenvironment in the evolution of the disease. In 2004, a landmark study by Dave et al. first described the microenvironment impact on tumor biology. By gene expression profiling they identified two different immune response signatures, involving T-cells and macrophages which seemed to independently predict FL outcome, but their exact is not completely understood and different studies led to variable results. Subsequently, many workgroups identified in amount and distribution pattern of these different cell subsets features which can impact prognosis, this leading to hypothesizing the use of these parameters as surrogate markers of the molecular signature. We aimed to assess the possible contributions of micro-environmental components to FL transformation or progression, its relevance as a prognostic/predictive tool, and its potential role as an innovative therapeutic target. We used immunohistochemical techniques, focusing specifically on macrophages and T-cells subsets, and then found correlations between the presence, proportions, and distribution of these reactive cells and the clinical outcomes leading to the future development of a reliable tool for upfront risk stratification of patients affected by FL.