| 178321. |
- Lanni, Luigia, 1985-
(författare)
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Silicon Carbide BipolarTechnology for High Temperature Integrated Circuits
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The availability of integrated circuits (ICs) capable of 500 or 600° C operation can be extremely beneficial for many important applications, such as transportation and energy sector industry. It can in fact enable the realization of improved sensing and control of turbine engine combustion leading to better fuel efficiency and reduced pollution. In addition, the possibility of placing integrated circuits in engine hot-sections can significantly reduce the weight and improve the reliability of automobiles and aircrafts, eliminating extra wires and cooling systems.In order to develop such electronics semiconductors with superior high temperature characteristics compared to Si are required. Thanks to its wide bandgap, almost three times that of Si, Silicon carbide (SiC) has been suggested for this purpose. Its low intrinsic carrier concentration, orders of magnitude lower than that of Si, makes SiC devices capable of operating at much higher temperatures than Si devices.In this thesis solutions for 600° C SiC bipolar ICs have been investigated in depth at device physics, circuit and process integration level. Successful operation of devices and circuits has been proven from -40 up to 600° C.The developed technology features NPN and lateral PNP transistors, two levels of interconnects and one extra metal level acting as over-layer metallization for device contacts. The improved SiC etching and passivation procedures have provided NPN transistors with high current gain of approximately 200. Furthermore, non-monotonous current gain temperature dependences have been observed for NPN and PNP transistors. The current gain of NPN transistors increases with temperature at high enough temperatures above 300° C depending on the base doping concentration. The current gain of lateral PNP transistors has, instead, shown a maximum of approximately 37 around 0° C.Finally, high-temperature operation of 2-input ECL-based OR-NOR gates and 3- and 11-stage ring oscillators has been demonstrated. For the OR-NOR gates stable noise margins of approximately 1 or 1.5 V, depending on the gate design, have been observed up to 600° C with a delay-power consumption product of approximately 100 nJ in the range -40 to 500° C. Ring oscillators with different designs, including more than 100 devices, have been successfully tested in the range 27 to 300° C. Non-monotonous and almost constant temperature dependences have been observed for the oscillation frequency of 3- and 11-stage ring oscillator, respectively. In addition, room temperature propagation delays of a single inverter stage have been estimated to be approximately 100 and 40 ns for 3- and 11-stage ring oscillators, respectively.
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| 178322. |
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| 178323. |
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| 178324. |
- Lannsjö, Marianne, 1956-
(författare)
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Mild Traumatic Brain Injury : Studies on outcome and prognostic factors
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: To explore the prevalence and structure of self-reported disability after mild traumatic brain injury and the impact of traumatic brain pathology on such outcome.Material and methods: In study 1-3, symptoms data were collected by use of Rivermead Post-concussion Symptoms Questionnaire (RPQ) and data on global function by use of Glasgow Outcome Scale Extended (GOSE) from 2602 patients at 3 months after MTBI. RPQ data were subject to factor and Rasch-analyses Head CT data from 1262 patients were used in a prediction analysis that also included age and gender. In study 4, MRI and symptoms data were collected at 2-3 days and at 3-7 months follow-up after MTBI in 19 patients. Global function was assessed at follow-up by use of the Rivermead Head Injury Follow-Up Questionnaire (RHIFUQ) and GOSE.Results: I. Most respondents reported no remaining symptoms but 24% reported ≥3 and 10% ≥7 remaining symptoms. The factor analysis demonstrated that all symptoms are correlated but also identified subgroups of symptoms. II. Rasch-analysis of RPQ showed disordered category function, local dependency of items, poor targeting of persons to items and indications of 3 or more dimensions. There was no differential item functioning. III. Head CT pathology with no need for acute intervention was observed in 52 patients (4%) but was not associated with either frequency of remaining symptoms or global outcome at 3 months post injury. Female gender and age over 30 years were associated with less favourable outcome with respect to symptoms and GOSE. IV. Post-acute MRI indicated trauma-related pathology in one patient and follow-up MRI indicated loss of brain volume in 4 patients.Conclusions: A substantial proportion of patients with MTBI report remaining problems at three months after MTBI. RPQ is useful but not optimal to assess symptoms outcome after MTBI and calculation of a total sum score is not recommended. Female gender and older age are negative prognostic factors while brain pathology according to CT has no effect on self-reported outcome. Loss of brain volume after MTBI according to MRI may be a sensitive marker of traumatic brain pathology and deserves further studies.
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| 178325. |
- Lanot, Gauthier, et al.
(författare)
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An empirical model of the decision to switch betweenelectricity price contracts
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We present a novel model for a time series of individual binary decisions which depends on the history of prices. The model is based on the Bayesian learning procedure which is at the core of sequential decision making. We show that the model capture dependence on past events and past priors in a straightforward fashion, the model capture some dependence on initial condition, here in the form of the prior at the start of the decision period, and that estimation through maximum likelihood is straightforward. We estimate the parameters of the model on a sample of Swedish households who have to decide over time between competing electricity contracts. The estimated parameters suggest that households respond to prices by switching between contracts, and that the response can be rather substantial for alternative price processes
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| 178326. |
- Lanot, Gauthier
(författare)
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French idiosyncracies
- 2016
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Ingår i: The contradictions of Capital in the twenty-first century. - : Agenda. - 9781911116103 - 9781911116110 ; , s. 67-85
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 178327. |
- Lanot, Gauthier, et al.
(författare)
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Mortgage loan characteristics, unobserved heterogeneity and the performance of United Kingdom securitised sub-prime loans
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The research estimates a competing risk model of mortgage terminations on samples of UK securitised subprime mortgages. Given the argued role of these types of loan in the recent financial crisis then it is important to better understand their performance and supposed idiosyncratic behaviour. The methodological and empirical advance is the use of a general, flexible modelling of unobserved heterogeneity over several dimensions, controlling for both selection issues involving initial mortgage choices and dynamic selection over time. Moreover, we estimate specific coefficients for this unobserved heterogeneity and determine the correlation between the unobserved components of default and prepayment. The paper demonstrates the need for researchers and practitioners to jointly estimate household choices whiles controlling for selectivity through unobserved heterogeneity.
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| 178328. |
- Lanot, Gauthier
(författare)
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The Marginal Rate of Substitution and the Specification of Labour Supply Models
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this note I revisit Heckman's proposal, [Heckman, 1974], to specify a static labour supply model using a simple formulation for the Marginal Rate of Substitution between total expenditure on consumption and hours of work. I describe the analytical form of the expenditure function and I show how the direct and indirect utility functions can be recovered. I propose an alternative specification for the MRS and in this case I describe analytically the labour supply functions, the indirect and direct utility functions as well as the expenditure function.
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| 178329. |
- Lanot, Gauthier
(författare)
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The Marginal Rate of Substitution and the Specification of Labour Supply Models
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this note I revisit Heckman's proposal, [Heckman, 1974], to specify a static labour supply model using a simple formulation for the Marginal Rate of Substitution between total expenditure on consumption and hours of work. I describe the analytical form of the expenditure function and I show how the direct and indirect utility functions can be recovered. I propose an alternative specification for the MRS and in this case I describe analytically the labour supply functions, the indirect and direct utility functions as well as the expenditure function.
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| 178330. |
- Lanot, Gauthier, et al.
(författare)
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The Minimum Wage and a Non-Competitive Market for Qualifications
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we consider an equilibrium model of demand and supply for several qualifications first in a competitive setting and then in a non-competitive setting. We propose a tractable analytical framework, i.e. when workers choose between qualifications according to a multinomial logit model of choice and when a CES production function describes the substitutions possibilities between the different types of labour. While in the competitive case the effects of the minimum wage are those we expect, in the imperfectly competitive case we find that a minimum wage can create unemployment and we find that the welfare of the population as a function of the minimum wage is not unimodal. We show furthermore that allowing one qualification to be exempted from the minimum wage does not mean that its relative demand is unaffected by changes to the minimum wage.
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