Wigner-function formalism applied to semiconductor quantum devices: Failure of the conventional boundary-condition scheme

The Wigner-function formalism is a well known approach to model charge transport in semiconductor nanodevices. Primary goal of the present article is to point out and explain intrinsic limitations of the conventional quantum-device modeling based on such Wigner-function paradigm, providing a definite answer to open questions related to the application of the conventional spatial boundary-condition scheme to the Wigner transport equation. Our analysis shows that (i) in the absence of energy dissipation (coherent limit) the solution of the Wigner equation equipped with given boundary conditions is not unique, and (ii) when decoherence/dissipation phenomena are taken into account via a relaxation-time approximation the solution, although unique, is not necessarily a physical Wigner function.Comment: 18 pages, 8 figures, accepted by Phys. Rev.

The consumer empowerment index. A measure of skills, awareness and engagement of European consumers

The Consumer Empowerment Index is a pilot exercise, aimed at obtaining a first snapshot of the state of consumer empowerment as measured by the Eurobarometer survey (Special Eurobarometer n. 342). It is neither a final answer on empowerment nor a comprehensive study on all the different facets of consumer empowerment, but instead it is meant to foster the debate on the determinants of empowerment and their importance for protecting consumers. This report describes the steps followed in the construction of the Index of consumer Empowerment. In particular the definition of the theoretical framework, the quantification of categorical survey questions, the univariate and multivariate analysis of the dataset, and the set of weight used for calculating the scores and ranks of the Index. The report also discusses the robustness of the results and the relationship between the Index and the socio-economic characteristics of the respondents in order to identify the features of the most vulnerable consumers. The Consumer Empowerment Index identifies Norway as the leading country followed by Finland, the Netherlands and Germany and Denmark. The middle of the ranking is dominated by western countries such as Belgium, France, and UK, with an average score 13% lower than the top five. At the bottom of the Index are some Eastern and Baltic countries like Bulgaria, Lithuania, Poland, and Romania with a score 31% lower on average (this gap reaches 40% and 38% in Awareness of consumer legislation and Consumer skills). A group of southern countries, Italy, Portugal, and Spain score poorly in the Index, especially in the pillar Consumer skills where the gap with the top performers reaches 30%.Consumer empowerment; composite indicators

The Consumer Empowerment Index

The 2007-2013 EU Consumer Policy Strategy emphasizes the importance of a better understanding of how consumers behave and sets as a main objective “to empower EU consumers”. A thorough knowledge of the capacities, information and assertiveness of consumers is considered crucial for being able to design and develop policies for consumer protection. Using the special Eurobarometer Survey n. 342, the DG Joint Research Center (together with DG Health and Consumers) constructed a composite measure of consumer empowerment encompassing the plurality of aspects implied by the EU policy Strategy. The resulting Consumer Empowerment Index describes consumer empowerment along three main dimensions: Consumer skills, Awareness of consumer legislation and Consumer engagement. The Index covers all 27 European countries plus Iceland and Norway. This report illustrates the different steps on the construction of the Index: the quantification of survey questions, the univariate and multivariate analysis of the dataset, the definition of an operational framework as well the selection of weights. Robustness analysis against alternative methodological choices is included. The relationship between socio economic characteristics of respondents and their level of empowerment is also presented with the aim of characterising the most crucial socio-economic determinants of empowerment and foster the debate on consumer protection.JRC.DG.G.3-Econometrics and applied statistic

Microscopic treatment of energy dissipation and decoherence via many-body Lindblad superoperators

Starting from a recent reformulation of the Markov limit, we apply the mean-field approximation to the resulting Lindblad-type many-electron dynamics, and derive a closed equation of motion for the electronic single-particle density matrix in the presence of one- and two-body scattering mechanisms. The proposed formulation preserves the positive-definite character of the single-particle density matrix. This result is in striking contrast with conventional Markov approaches, where the single-particle mean-field equations can lead to positivity violations and therefore to unphysical results

Derivation of nonlinear single-particle equations via many-body Lindblad superoperators: A density-matrix approach

A recently proposed Markov approach provides Lindblad-type scattering superoperators, which ensure the physical (positive-definite) character of the many-body density matrix. We apply the mean-field approximation to such a many-body equation, in the presence of one- and two-body scattering mechanisms, and we derive a closed equation of motion for the electronic single-particle density matrix, which turns out to be nonlinear as well as non-Lindblad. We prove that, in spite of its nonlinear and non-Lindblad structure, the mean-field approximation does preserve the positive-definite character of the single-particle density matrix, an essential prerequisite of any reliable kinetic treatment of semiconductor quantum devices. This result is in striking contrast with conventional (non-Lindblad) Markov approaches, where the single-particle mean-field equations can lead to positivity violations and thus to unphysical results. Furthermore, the proposed single-particle formulation is extended to the case of quantum systems with spatial open boundaries, providing a formal derivation of a recently proposed density-matrix treatment based on a Lindblad-like system-reservoir scattering superoperator

Notch signaling sustains the expression of Mcl-1 and the activity of eIF4E to promote cell survival in CLL

In chronic lymphocytic leukemia (CLL), Notch1 and Notch2 signaling is constitutively activated and contributes to apoptosis resistance. We show that genetic inhibition of either Notch1 or Notch2, through small-interfering RNA, increases apoptosis of CLL cells and is associated with decreased levels of the anti-apoptotic protein Mcl-1. Thus, Notch signaling promotes CLL cell survival at least in part by sustaining Mcl-1 expression. In CLL cells, an enhanced Notch activation also contributes to the increase in Mcl-1 expression and cell survival induced by IL-4.Mcl-1 downregulation by Notch targeting is not due to reduced transcription or degradation by caspases, but in part, to increased degradation by the proteasome. Mcl-1 downregulation by Notch targeting is also accompanied by reduced phosphorylation of eukaryotic translation initiation factor 4E (eIF4E), suggesting that this protein is another target of Notch signaling in CLL cells.Overall, we show that Notch signaling sustains CLL cell survival by promoting Mcl-1 expression and eIF4E activity, and given the oncogenic role of these factors, we underscore the therapeutic potential of Notch inhibition in CLL

Tinnitus and Self-Perceived Hearing Handicap in Firefighters: a Cross-Sectional Study

Firefighters are susceptible to auditory dysfunction due to long-term exposure to noise from sirens, air horns, equipment, and tools used in forcible entry, ventilation, and extrication. In addition, they are exposed to ototoxic chemicals, particularly, during overhaul operations. Studies indicate that 40% of firefighters have hearing loss in the noise-sensitive frequencies of 4 and 6 kHz. Noise-induced hearing loss (NIHL) is often accompanied by tinnitus, which is characterized by ringing noise in the ears. The presence of phantom sounds can adversely affect the performance of firefighters. However, there has been limited research conducted on the prevalence of tinnitus in firefighters. We enrolled firefighters from Michigan, with at least 5 years of continuous service. The hearing handicap inventory for adults (HHIA) was used to determine the difficulty in hearing perceived by the firefighters and the tinnitus functional index (TFI) was used to determine the severity of tinnitus. Self-perceived hearing handicap was reported by 36% of the participants, while tinnitus was reported by 48% of the participants. The TFI survey indicated that 31% perceived tinnitus as a problem. More importantly, self-perceived hearing handicap was significantly associated with the incidence of tinnitus in firefighters, suggesting a potential link between occupational exposure to ototraumatic agents and tinnitus in firefighters

Genetic study of Murgese horse from genealogical data and microsatellites

The black or rarely roan Murgese is a mesomorph horse, mainly reared in Apulia, recently selected for the saddle. Thefirst official registry of Murgese was established in 1926. All the existing Murgese horses can be traced back to a smallnumber of founders (46 founder mares and 9 stallions). This work aims to monitor the genetic structure of the actualpopulation by analysing the available genealogical information from 2708 animals and a data-set containing 563 typingrecords of twelve microsatellites. Inbreeding coefficients were estimated for the whole sample and for the animals bornfrom 1992 to 1999. A total of 23 generations were found. The average inbreeding coefficient was 0.0165 for the last threegenerations, whereas inbreeding was below 2% in animals born in the 92-99 period. The contribution of founders wasunbalanced. The overall FIS coefficient estimation was 0.025 and suggests that mating is generally at random in the population.However, some statistics obtained from this study, i.e. the inbreeding coefficient higher than 0.015 in the 70 animalsof the 19th, 20th, and 21st generations, should induce breeders to more attention in planning mating

The consumer empowerment index. A measure of skills, awareness and engagement of European consumers

The Consumer Empowerment Index is a pilot exercise, aimed at obtaining a first snapshot of the state of consumer empowerment as measured by the Eurobarometer survey (Special Eurobarometer n. 342). It is neither a final answer on empowerment nor a comprehensive study on all the different facets of consumer empowerment, but instead it is meant to foster the debate on the determinants of empowerment and their importance for protecting consumers. This report describes the steps followed in the construction of the Index of consumer Empowerment. In particular the definition of the theoretical framework, the quantification of categorical survey questions, the univariate and multivariate analysis of the dataset, and the set of weight used for calculating the scores and ranks of the Index. The report also discusses the robustness of the results and the relationship between the Index and the socio-economic characteristics of the respondents in order to identify the features of the most vulnerable consumers. The Consumer Empowerment Index identifies Norway as the leading country followed by Finland, the Netherlands and Germany and Denmark. The middle of the ranking is dominated by western countries such as Belgium, France, and UK, with an average score 13% lower than the top five. At the bottom of the Index are some Eastern and Baltic countries like Bulgaria, Lithuania, Poland, and Romania with a score 31% lower on average (this gap reaches 40% and 38% in Awareness of consumer legislation and Consumer skills). A group of southern countries, Italy, Portugal, and Spain score poorly in the Index, especially in the pillar Consumer skills where the gap with the top performers reaches 30%