Refraction in spacetime

Refraction, interference, and diffraction are distinguishing features of wavelike phenomena. Although they are usually associated only with a purely spatial wave-propagation pattern, analogs to interference and diffraction involving the spatio-temporal dynamics of waves in one dimension have been discussed. We complete the triplet of analogies by discussing how spatio-temporal analogs to refraction are exhibited by a quantum particle in one dimension that is scattering off a step barrier. Similarly, birefringence in spacetime occurs for a spin-1/2 particle in a magnetic field.

Actitudes hacia el murciano : Un estudio comparativo de actitudes que presentan nativosmurcianos e hispanohablantes no peninsulares.

Murciano is a non-standard variety that is spoken in Murcia, a region in the southeast of Spain.This study aims to investigate which are the attitudes toward the variety from the dimensions ofsolidarity and status.We will use two groups of informants. One integrated by 20 natives from Murcia who use thevariety, and the other by 16 non-spanish-natives that have never been in contact with murciano.The intention with the study is to investigate which attitudes both groups show towardmurciano and analyse the differences and similarities between them. We expect the natives toshow positive attitudes in the dimension of solidarity, and negatives in the dimension of status.We expect the non-natives to show the same kind of attidudes toward both varieties (thestandard-spanish and murciano) while they have never been in contact with the non-standardand therefore should not have the sociocultural background that help people to create negativeattitudes toward non-standard varieties.The chosen method is an indirect one, and the used technique is the matched-guise. Theinformants listen to two different voices talking two times each: one in standard-spanish andone in murciano. After they have listened to one voice in one variety they answer 10 differentquestions to measure their attitudes in the both dimensions we aim to investigate. The resultsare analysed from the gender and the education variables.The results show that the natives attitudes toward murciano are positives from the solidaritydimension but negatives from the status one, results that confirm the first hypothesis. However,the study shows that the non-natives also have negative attitudes toward the variety in the statusdimension but positive toward the standard-spanish, which means that the second hypothesiswas wrong, something that could have been caused by the fact that all non-natives had a higheducational-level. Other studies show that education is a factor that can have a bearing onhaving negative attitudes toward non-standard varieties.

Estudio comparativo de las actitudes hacia elmurciano.

The aim of this study is to measure and analyse the attitudes towards a linguisticvariety called murciano. This variety is a regional standard of Spanish, namely, theSpanish talked in Murcia, a city located in the South of Spain.There are two groups of informants in this study. The first group is composed of12 people from Murcia and the second group consists of 12 people who know thevariety of murciano but are not natives from the city of Murcia. The methodapplied is the indirect method matched guise. The informants listened to fourdifferent recordings of voices acting as either a Spanish speaking person or amurciano speaking person. Ten short questions related with the voices were askedto the informants, who gave their answers on a Likert attitude scale.The results show that the attitudes towards murciano and the standard Spanishdiffer in both groups of informants. The group of natives from Murcia show morepositive attitudes toward the variety murciano than the group of non-natives fromMurcia. However, when the results towards the variety murciano and the standardSpanish are compared with each other, it is the standard Spanish the one thatreceives more positive valuations. In addition, the observations show that thegroup of non-natives from Murcia are more critical and negative in their attitudestoward the different linguistic varieties than the group of natives from Murcia.

Essays on firm dynamics in the Swedish wholesale trade sector

This thesis consists of a summary and five self-contained papers addressing dynamics of firms in the Swedish wholesale trade sector. Paper [1] focuses upon determinants of new firm formation in the Swedish wholesale trade sector, using two definitions of firms’ relevant markets, markets defined as administrative areas, and markets based on a cost minimizing behavior of retailers. The paper shows that new entering firms tend to avoid regions with already high concentration of other firms in the same branch of wholesaling, while right-of-the-center local government and quality of the infrastructure have positive impacts upon entry of new firms. The signs of the estimated coefficients remain the same regardless which definition of relevant market is used, while the size of the coefficients is generally higher once relevant markets delineated on the cost-minimizing assumption of retailers are used. Paper [2] analyses determinant of firm relocation, distinguishing between the role of the factors in in-migration municipalities and out-migration municipalities. The results of the analysis indicate that firm-specific factors, such as profits, age and size of the firm are negatively related to the firm’s decision to relocate. Furthermore, firms seems to be avoiding municipalities with already high concentration of firms operating in the same industrial branch of wholesaling and also to be more reluctant to leave municipalities governed by right-of-the- center parties. Lastly, firms seem to avoid moving to municipalities characterized with high population density. Paper [3] addresses determinants of firm growth, adopting OLS and a quantile regression technique. The results of this paper indicate that very little of the firm growth can be explained by the firm-, industry- and region-specific factors, controlled for in the estimated models. Instead, the firm growth seems to be driven by internal characteristics of firms, factors difficult to capture in conventional statistics. This result supports Penrose’s (1959) suggestion that internal resources such as firm culture, brand loyalty, entrepreneurial skills, and so on, are important determinants of firm growth rates. Paper [4] formulates a forecasting model for firm entry into local markets and tests this model using data from the Swedish wholesale industry. The empirical analysis is based on directly estimating the profit function of wholesale firms and identification of low- and high-return local markets. The results indicate that 19 of 30 estimated models have more net entry in high-return municipalities, but the estimated parameters is only statistically significant at conventional level in one of our estimated models, and then with unexpected negative sign. Paper [5] studies effects of firm relocation on firm profits of relocating firms, employing a difference-in-difference propensity score matching. Using propensity score matching, the pre-relocalization differences between relocating and non-relocating firms are balanced, while the difference-in-difference estimator controls for all time-invariant unobserved heterogeneity among firms. The results suggest that firms that relocate increase their profits significantly, in comparison to what the profits would be had the firms not relocated. This effect is estimated to vary between 3 to 11 percentage points, depending on the length of the analyzed period. 

Attitudes towards the minority variety Caló in the south of Spain : a sociolinguistic study

Caló is a variety spoken by the Spanish Calé (i.e. the Roma). It belongs to a group of languages referred to as “Para-Romani”, characterized by Romani vocabulary, but largely non-Romani morphology, phonology and syntax, in the case of Caló deriving from Spanish. According to previous research carried out – with focus on the vocabulary and the grammar of this variety – Caló is on its way to extinction. However, there is an expressed interest in reintroducing a form called “Romanó-Caló”. Attitudes play an important role in minority language maintenance as well as in order for a revitalization project to be successful. The aim of this study is to measure the attitudes that both Calé and non-Calé have towards Caló and Caló speakers, a type of study never carried out in the past. The methods applied are both direct and indirect. In total, 231 informants listened to different recordings of voices acting as either a “Spanish speaking person” or a “Caló speaking person”, a technique referred to as ‘matched guise’, answering questions related to the voices on attitude scales. Furthermore, 182 of the informants rated their agreement or disagreement to positive and negative items towards Caló and its speakers on a Likert scale. The results of the analysis indicate that the attitudes differ towards Caló and Caló speakers, depending on the informant’s (a) ethnicity (b) contact with Caló as well as with Caló speakers, and (c) gender. It is those who – in their own opinion – belong to the ethnic group Calé, as well as those who claim that they have some contact with the variety and its speakers, who show positive attitudes in both parts of the study. The women also show more positive attitudes than the men. It is also possible to note positive attitudes towards the variety and its speakers among the subjects with a high level of knowledge of Caló words, as well as among those with the highest willingness to use Caló. These observations suggest that a revitalization project of the variety Caló has a clear chance of being successful.

Automatic spiral analysis for objective assessment of motor symptoms in Parkinson's disease

A challenge for the clinical management of advanced Parkinson’s disease (PD) patients is the emergence of fluctuations in motor performance, which represents a significant source of disability during activities of daily living of the patients. There is a lack of objective measurement of treatment effects for in-clinic and at-home use that can provide an overview of the treatment response. The objective of this paper was to develop a method for objective quantification of advanced PD motor symptoms related to off episodes and peak dose dyskinesia, using spiral data gathered by a touch screen telemetry device. More specifically, the aim was to objectively characterize motor symptoms (bradykinesia and dyskinesia), to help in automating the process of visual interpretation of movement anomalies in spirals as rated by movement disorder specialists. Digitized upper limb movement data of 65 advanced PD patients and 10 healthy (HE) subjects were recorded as they performed spiral drawing tasks on a touch screen device in their home environment settings. Several spatiotemporal features were extracted from the time series and used as inputs to machine learning methods. The methods were validated against ratings on animated spirals scored by four movement disorder specialists who visually assessed a set of kinematic features and the motor symptom. The ability of the method to discriminate between PD patients and HE subjects and the test-retest reliability of the computed scores were also evaluated. Computed scores correlated well with mean visual ratings of individual kinematic features. The best performing classifier (Multilayer Perceptron) classified the motor symptom (bradykinesia or dyskinesia) with an accuracy of 84% and area under the receiver operating characteristics curve of 0.86 in relation to visual classifications of the raters. In addition, the method provided high discriminating power when distinguishing between PD patients and HE subjects as well as had good test-retest reliability. This study demonstrated the potential of using digital spiral analysis for objective quantification of PD-specific and/or treatment-induced motor symptoms.