Extreme River Floods in Western Switzerland and the Lake of Constance Region in the Period Prior to Instrumental Measurements

The floods that occurred on the Aare and Rhine rivers in May 2015 and the mostly successful handling of this event in terms of flood protection measures are a good reminder of how important it is to comprehend the causes and processes involved in such natural hazards. While the needed data series of gauge measurements and peak discharge calculations reach back to the 19th century, historical records dating further back in time can provide additional and useful information to help understanding extreme flood events and to evaluate prevention measures such as river dams and corrections undertaken prior to instrumental measurements. In my PhD project I will use a wide range of historical sources to assess and quantify past extreme flood events. It is part of the SNF-funded project “Reconstruction of the Genesis, Process and Impact of Major Pre-instrumental Flood Events of Major Swiss Rivers Including a Peak Discharge Quantification” and will cover the research locations Fribourg (Saane R.), Burgdorf (Emme R.), Thun, Bern (both Aare R.), and the Lake of Constance at the locations Lindau, Constance and Rorschach. My main goals are to provide a long time series of quantitative data for extreme flood events, to discuss the occurring changes in these data, and to evaluate the impact of the aforementioned human influences on the drainage system. Extracting information given in account books from the towns of Basel and Solothurn may also enable me to assess the frequency and seasonality of less severe river floods. Finally, historical information will be used for remodeling the historical hydrological regime to homogenize the historical data series to modern day conditions and thus make it comparable to the data provided by instrumental measurements. The method I will apply for processing all information provided by historical sources such as chronicles, newspapers, institutional records, as well as flood marks, paintings and archeological evidence has been developed and successfully applied to the site of Basel by Wetter et al. (2011). They have also shown that data homogenization is possible by reconstructing previous stream flow conditions using historical river profiles and by carefully observing and re-constructing human changes of the river bed and its surroundings. Taken all information into account, peak discharges for past extreme flood events will be calculated with a one-dimensional hydrological model.

Holocene palaeoclimate and palaeovegetation on the islands of Flores and Pico

Palaeoclimatic stability is regarded as an important factor in explaining patterns of endemism in the Azorean flora. However, modelling simulations and quantitative reconstructions for the last 6000 years suggest considerable palaeoclimatic variability. Here we explore the link between Holocene palaeoclimate and palaeovegetation on the islands of Flores and Pico. Modern pollen assemblages indicate that most major plant communities can be detected using pollen analysis and that, in some cases, the pre-colonisation vegetation was quite similar to present-day relict vegetation. A 200–500-year pollen record from Alagoinha, a low-elevation mire in western Flores, shows that Juniperus brevifolia-dominated communities were widespread at lower elevations prior to large-scale deforestation. Today these communities are generally restricted to higher elevations. While our results are preliminary, there appears to be a weak link between palaeovegetation (which was primarily influenced by volcanism, soil formation and human impact) and palaeoclimatic changes detected through geochemical proxies. Even if the Azorean palaeoclimate varied substantially, its impact on the pristine vegetation, at least in terms of pollen production, was relatively small.

Phenotypic plasticity is a negative, though weak, predictor of the commonness of 105 grassland species

Aim The usual hypothesis about the relationship between niche breadth and range size posits that species with the capacity to use a wider range of resources or to tolerate a greater range of environmental conditions should be more widespread. In plants, broader niches are often hypothesized to be due to pronounced phenotypic plasticity, and more plastic species are therefore predicted to be more common. We examined the relationship between the magnitude of phenotypic plasticity in five functional traits, mainly related to leaves, and several measures of abundance in 105 Central European grassland species. We further tested whether mean values of traits, rather than their plasticity, better explain the commonness of species, possibly because they are pre-adapted to exploiting the most common resources. Location Central Europe. Methods In a multispecies experiment with 105 species we measured leaf thickness, leaf greenness, specific leaf area, leaf dry matter content and plant height, and the plasticity of these traits in response to fertilization, waterlogging and shading. For the same species we also obtained five measures of commonness, ranging from plot-level abundance to range size in Europe. We then examined whether these measures of commonness were associated with the magnitude of phenotypic plasticity, expressed as composite plasticity of all traits across the experimental treatments. We further estimated the relative importance of trait plasticity and trait means for abundance and geographical range size. Results More abundant species were less plastic. This negative relationship was fairly consistent across several spatial scales of commonness, but it was weak. Indeed, compared with trait means, plasticity was relatively unimportant for explaining differences in species commonness. Main conclusions Our results do not indicate that larger phenotypic plasticity of leaf morphological traits enhances species abundance. Furthermore, possession of a particular trait value, rather than of trait plasticity, is a more important determinant of species commonness.

Corruption and Growth Under Weak Identification

The goal of this paper is to revisit the influential work of Mauro [1995] focusing on the strength of his results under weak identification. He finds a negative impact of corruption on investment and economic growth that appears to be robust to endogeneity when using two-stage least squares (2SLS). Since the inception of Mauro [1995], much literature has focused on 2SLS methods revealing the dangers of estimation and thus inference under weak identification. We reproduce the original results of Mauro [1995] with a high level of confidence and show that the instrument used in the original work is in fact 'weak' as defined by Staiger and Stock [1997]. Thus we update the analysis using a test statistic robust to weak instruments. Our results suggest that under Mauro's original model there is a high probability that the parameters of interest are locally almost unidentified in multivariate specifications. To address this problem, we also investigate other instruments commonly used in the corruption literature and obtain similar results.

Emerging Identities in Colonial Tunisia: "Alliancist" and Zionist Representations in Tunis prior to World War I

By 1900 the Jewish community of Tunisia witnessed the emergence of new competing identities: “assimilationist” of the Alliance Israelite Universelle, termed “Alliancist,” and Zionist. Strikingly, two members of the same family in Tunis, Raymond Valensi, President of the AIU Regional Committee, and Alfred Valensi, President of the Zionist Federation, led the struggle for their separate causes. In his discussion of identity in the modern world, Homi Bhabha asks, "How do strategies of representation or empowerment come to be formulated in the competing claims of communities…where, despite shared histories of …discrimination, the exchange of values, meanings and priorities…may be profoundly antagonistic…?" It is in this context that the claims of the Alliance and Zionism will be examined prior to World War I, based on the Archives of the AIU and on such secondary sources as the indispensable work of Paul Sebag. The tensions between the Alliancists and Zionists continued until the outbreak of World War II, as the French-speaking Jews of Tunisia sought to define their individual and collective identities.

A Simple Statistical Test of Violation of the Weak Axiom of Cost Minimization

A problem with a practical application of Varian.s Weak Axiom of Cost Minimization is that an observed violation may be due to random variation in the output quantities produced by firms rather than due to inefficiency on the part of the firm. In this paper, unlike in Varian (1985), the output rather than the input quantities are treated as random and an alternative statistical test of the violation of WACM is proposed. We assume that there is no technical inefficiency and provide a test of the hypothesis that an observed violation of WACM is merely due to random variations in the output levels of the firms being compared.. We suggest an intuitive approach for specifying a value of the variance of the noise term that is needed for the test. The paper includes an illustrative example utilizing a data set relating to a number of U.S. airlines.

De anima brutorum quae hominis vitalis ac sensitiva est exercitationes : 2. Prior physiologica eiusdem naturam, partes, petentias et affectiones tradit : altera pathologica morbos qui ipsam, & sedem eius primariam, ...

studio Thomae Willis

Prior history of atopy or autoimmunity increases risk for alopecia areata

Background. The association between a prior history of atopy or other autoimmune diseases and risk of alopecia areata is not well established. ^ Objective. Purpose of this study was to use the National Alopecia Areata Registry database to further investigate the association between history of atopy or other autoimmune diseases and risk of alopecia areata. ^ Methods. A total of 2,613 self-registered sporadic cases (n = 2,055) and controls (n = 558) were included in the present analysis. ^ Results. Possessing a history of any atopy (OR = 2.00; 95% CI 1.50-2.54) or autoimmune disease (OR = 1.73; 95% CI 1.10-2.72) was associated with an increased risk of alopecia areata. There was no trend for possessing a history of more than one atopy or autoimmune disease and increasing risk of alopecia areata. ^ Limitations. Recall, reporting, and recruiting bias are potential sources of limitations in this analysis. ^ Conclusion. This analysis revealed that a prior history of atopy and autoimmune disease was associated with an increased risk of alopecia areata and that the results were consistent for both the severe subtype of alopecia areata (i.e., alopecia totalis and alopecia universalis) and the localized subtype (i.e., alopecia areata persistent).^

A systematic review of selected birth outcomes in diabetic women who received preconception care and/or used multivitamins prior to pregnancy

Objective. To conduct a systematic review of published literature on preconception care in pre-existing diabetic women looking at the effect of glycemic control and multivitamin usage on the frequency of spontaneous abortion and birth defects.^ Methods. Articles were retrieved from Medline (1950–Dec 2007), Cochrane Library (1800–Dec 2007), Academic Search Complete (Ebsco) (Jan 1800–Dec 2007) and Maternal and Child Health Library (1965–Dec 2007). Studies included women with pre-existing, non-gestational diabetes and a comparison group. Participants must have either received preconception care and/or consumed a multivitamin as part of the study.^ Results. Overall, seven studies met the study criteria and applicability to the study objectives. Four of these reported the frequency of spontaneous abortion. Only one found a statistically significant increased risk of spontaneous abortion among pregnant women who did not receive preconception care compared with those who did receive care, odds ratio 4.32; 95% CI 1.34 to 13.9. Of the seven studies, six reported the frequency of birth defects. Five of these six studies found a significantly increased rate of birth defects among pregnant women who did not receive preconception care compared with those who did receive care, with odds ratios ranging from 1.53 to 10.16. All seven studies based their preconception care intervention on glycemic control. One study also used multivitamins as part of the preconception care.^ Conclusion. Glycemic control was shown to be useful in reducing the prevalence of birth defects, but not as useful in reducing the prevalence of spontaneous abortion. Insulin regimen options vary widely for the diabetic woman. No author excluded or controlled for women who may have been taking a multivitamin on their own. Due to the small amount of literature available, it is still not known which preconception care option, glucose control and/or multivitamin usage, provides better protection from birth defects and spontaneous abortion for the diabetic woman. An area for future investigation would be glycemic control and the use of folic acid started before pregnancy and the effects on birth defects and spontaneous abortion.^

Effects of informative censoring on the hazard function: Application to the proportional hazards regression model

The standard analyses of survival data involve the assumption that survival and censoring are independent. When censoring and survival are related, the phenomenon is known as informative censoring. This paper examines the effects of an informative censoring assumption on the hazard function and the estimated hazard ratio provided by the Cox model.^ The limiting factor in all analyses of informative censoring is the problem of non-identifiability. Non-identifiability implies that it is impossible to distinguish a situation in which censoring and death are independent from one in which there is dependence. However, it is possible that informative censoring occurs. Examination of the literature indicates how others have approached the problem and covers the relevant theoretical background.^ Three models are examined in detail. The first model uses conditionally independent marginal hazards to obtain the unconditional survival function and hazards. The second model is based on the Gumbel Type A method for combining independent marginal distributions into bivariate distributions using a dependency parameter. Finally, a formulation based on a compartmental model is presented and its results described. For the latter two approaches, the resulting hazard is used in the Cox model in a simulation study.^ The unconditional survival distribution formed from the first model involves dependency, but the crude hazard resulting from this unconditional distribution is identical to the marginal hazard, and inferences based on the hazard are valid. The hazard ratios formed from two distributions following the Gumbel Type A model are biased by a factor dependent on the amount of censoring in the two populations and the strength of the dependency of death and censoring in the two populations. The Cox model estimates this biased hazard ratio. In general, the hazard resulting from the compartmental model is not constant, even if the individual marginal hazards are constant, unless censoring is non-informative. The hazard ratio tends to a specific limit.^ Methods of evaluating situations in which informative censoring is present are described, and the relative utility of the three models examined is discussed. ^

Genetic epidemiology of gallbladder disease in Mexican Americans and cholesterol 7$\alpha$-hydroxylase gene sequence variation

Among Mexican Americans, the second largest minority group in the United States, the prevalence of gallbladder disease is markedly elevated. Previous data from both genetic admixture and family studies indicate that there is a genetic component to the occurrence of gallbladder disease in Mexican Americans. However, prior to this thesis no formal genetic analysis of gallbladder disease had been carried out nor had any contributing genes been identified.^ The results of complex segregation analysis in a sample of 232 Mexican American pedigrees documented the existence of a major gene having two alleles with age- and gender-specific effects influencing the occurrence of gallbladder disease. The estimated frequency of the allele increasing susceptibility was 0.39. The lifetime probabilities that an individual will be affected by gallbladder disease were 1.0, 0.54, and 0.00 for females of genotypes "AA", "Aa", and "aa", respectively, and 0.68, 0.30, and 0.00 for males, respectively. This analysis provided the first conclusive evidence for the existence of a common single gene having a large effect on the occurrence of gallbladder disease.^ Human cholesterol 7$\alpha$-hydroxylase is the rate-limiting enzyme in bile acid synthesis. The results of an association study in both a random sample and a matched case/control sample showed that there is a significant association between cholesterol 7$\alpha$-hydroxylase gene variation and the occurrence of gallbladder disease in Mexican Americans males but not in females. These data have implicated a specific gene, 7$\alpha$-hydroxylase, in the etiology of gallbladder disease in this population.^ Finally, I asked whether the inferred major gene from complex segregation analysis is genetically linked to the cholesterol 7$\alpha$-hydroxylase gene. Three pedigrees predicted to be informative for linkage analysis by virtue of supporting the major gene hypothesis and having parents with informative genotypes and multiple offspring were selected for this linkage analysis. In each of these pedigrees, the recombination fractions maximized at 0 with a positive, albeit low, LOD score. The results of this linkage analysis provide preliminary and suggestive evidence that the cholesterol 7$\alpha$-hydroxylase gene and the inferred gallbladder disease susceptibility gene are genetically linked. ^

FACTORS INFLUENCING THE PATTERNS OF PHYSICIAN VISITS TO NURSING HOME RESIDENTS

This study was designed to identify some of the factors related to patterns of physician visits to nursing home residents. The relationship of ten resident and organizational characteristics to patterns of physician visits was investigated through secondary analysis of data abstracted from the 1973-74 National Nursing Home Survey of the National Center for Health Statistics. The study sample was composed of 11,135 of the 19,013 nursing home residents who participated in the survey.^ The analytic results revealed that all ten variables had a statistically significant relationship to patterns of physician visits, mainly due to the large sample size. The degrees of association between the variables, measured by the Cramer's V statistic, ranged from moderate to very weak.^ Certification status of the nursing home under Medicare and/or Medicaid was shown to be most strongly related to patterns of physician visits, followed by primary source of payment for nursing home care, and residence prior to nursing home admission. Several variables thought to be related to patterns of physician visits were found to have a very weak relationship: age of the resident, marital status, length of stay, primary diagnosis, number of chronic conditions, activities of daily living status, and levels of care.^ In order to get a more precise picture of the relative influence of certification status and primary source of payment when the other variables were statistically controlled, these two variables were combined into a single variable. The results revealed that the combined effects of certification status and primary source of payment were sustained, regardless of differences in the residents' personal, utilization, and health status characteristics, and the levels of care that they received. The results also indicated that the five groups created by combining the two variables differed in patterns of physician visits. For example, private pay residents in intermediate care facilities (ICF's) and non-certified facilities were more likely to receive unscheduled visits than private pay residents in skilled nursing homes (SNH's), residents in SNH's supported by Medicare or Medicaid, and residents in ICF's supported by Medicaid. ^

Does prior receipt of a rifamycin antibiotic increase the risk of acquiring an infection due to a rifamycin-resistant strain of Clostridium difficile?

Objectives. To examine the association between prior rifamycin exposure and later development of C. difficile infection (CDI) caused by a rifamycin-resistant strain of C. difficile , and to compare patient characteristics between rifamycin-resistant strains of C. difficile infection and rifamycin-susceptible strains of C. difficile infection. ^ Methods. A case-control study was performed in a large university-affiliated hospital in Houston, Texas. Study subjects were patients with C. difficile infection acquired at the hospital with culture-positive isolates of C. difficile with which in vitro rifaximin and rifampin susceptibility has been tested. Prior use of rifamycin, demographic and clinical characteristics was compared between case and control groups using univariate statistics. ^ Results. A total of 49 C. difficile strains met the study inclusion criteria for rifamycin-resistant case isolates, and a total of 98 rifamycin-susceptible C. difficile strains were matched to case isolates. Of 49 case isolates, 12 (4%) were resistant to rifampin alone, 12 (4%) were resistant to rifaximin alone, and 25 (9%) were resistant to both rifampin and rifaximin. There was no significant association between prior rifamycin use and rifamycin-resistant CDI. Cases and controls did not differ according to demographic characteristics, length of hospital stay, known risk factors of CDI, type of CDI-onset, and pre-infection medical co-morbidities. Our results on 37 rifaximin-resistant isolates (MIC ≥32 &mgr;g/ml) showed more than half of isolates had a rifaximin MIC ≥256 &mgr;g/ml, and out of these isolates, 19 isolates had MICs ≥1024 &mgr;g/ml. ^ Conclusions. Using a large series of rifamycin-non-susceptible isolates, no patient characteristics were independently associated with rifamycin-resistant CDI. This data suggests that factors beyond previous use of rifamycin antibiotics are primary risk factors for rifamycin-resistant C. difficile. ^

BAYESIAN STATISTICAL METHODS IN GENE-ENVIRONMENT AND GENE-GENE INTERACTION STUDIES

Complex diseases such as cancer result from multiple genetic changes and environmental exposures. Due to the rapid development of genotyping and sequencing technologies, we are now able to more accurately assess causal effects of many genetic and environmental factors. Genome-wide association studies have been able to localize many causal genetic variants predisposing to certain diseases. However, these studies only explain a small portion of variations in the heritability of diseases. More advanced statistical models are urgently needed to identify and characterize some additional genetic and environmental factors and their interactions, which will enable us to better understand the causes of complex diseases. In the past decade, thanks to the increasing computational capabilities and novel statistical developments, Bayesian methods have been widely applied in the genetics/genomics researches and demonstrating superiority over some regular approaches in certain research areas. Gene-environment and gene-gene interaction studies are among the areas where Bayesian methods may fully exert its functionalities and advantages. This dissertation focuses on developing new Bayesian statistical methods for data analysis with complex gene-environment and gene-gene interactions, as well as extending some existing methods for gene-environment interactions to other related areas. It includes three sections: (1) Deriving the Bayesian variable selection framework for the hierarchical gene-environment and gene-gene interactions; (2) Developing the Bayesian Natural and Orthogonal Interaction (NOIA) models for gene-environment interactions; and (3) extending the applications of two Bayesian statistical methods which were developed for gene-environment interaction studies, to other related types of studies such as adaptive borrowing historical data. We propose a Bayesian hierarchical mixture model framework that allows us to investigate the genetic and environmental effects, gene by gene interactions (epistasis) and gene by environment interactions in the same model. It is well known that, in many practical situations, there exists a natural hierarchical structure between the main effects and interactions in the linear model. Here we propose a model that incorporates this hierarchical structure into the Bayesian mixture model, such that the irrelevant interaction effects can be removed more efficiently, resulting in more robust, parsimonious and powerful models. We evaluate both of the 'strong hierarchical' and 'weak hierarchical' models, which specify that both or one of the main effects between interacting factors must be present for the interactions to be included in the model. The extensive simulation results show that the proposed strong and weak hierarchical mixture models control the proportion of false positive discoveries and yield a powerful approach to identify the predisposing main effects and interactions in the studies with complex gene-environment and gene-gene interactions. We also compare these two models with the 'independent' model that does not impose this hierarchical constraint and observe their superior performances in most of the considered situations. The proposed models are implemented in the real data analysis of gene and environment interactions in the cases of lung cancer and cutaneous melanoma case-control studies. The Bayesian statistical models enjoy the properties of being allowed to incorporate useful prior information in the modeling process. Moreover, the Bayesian mixture model outperforms the multivariate logistic model in terms of the performances on the parameter estimation and variable selection in most cases. Our proposed models hold the hierarchical constraints, that further improve the Bayesian mixture model by reducing the proportion of false positive findings among the identified interactions and successfully identifying the reported associations. This is practically appealing for the study of investigating the causal factors from a moderate number of candidate genetic and environmental factors along with a relatively large number of interactions. The natural and orthogonal interaction (NOIA) models of genetic effects have previously been developed to provide an analysis framework, by which the estimates of effects for a quantitative trait are statistically orthogonal regardless of the existence of Hardy-Weinberg Equilibrium (HWE) within loci. Ma et al. (2012) recently developed a NOIA model for the gene-environment interaction studies and have shown the advantages of using the model for detecting the true main effects and interactions, compared with the usual functional model. In this project, we propose a novel Bayesian statistical model that combines the Bayesian hierarchical mixture model with the NOIA statistical model and the usual functional model. The proposed Bayesian NOIA model demonstrates more power at detecting the non-null effects with higher marginal posterior probabilities. Also, we review two Bayesian statistical models (Bayesian empirical shrinkage-type estimator and Bayesian model averaging), which were developed for the gene-environment interaction studies. Inspired by these Bayesian models, we develop two novel statistical methods that are able to handle the related problems such as borrowing data from historical studies. The proposed methods are analogous to the methods for the gene-environment interactions on behalf of the success on balancing the statistical efficiency and bias in a unified model. By extensive simulation studies, we compare the operating characteristics of the proposed models with the existing models including the hierarchical meta-analysis model. The results show that the proposed approaches adaptively borrow the historical data in a data-driven way. These novel models may have a broad range of statistical applications in both of genetic/genomic and clinical studies.

Exploring the perception and production of weak and strong forms in English

Como profesoras de Fonética y Fonología Inglesa hemos percibido que nuestros alumnos –hispano-hablantes- enfrentan una serie de dificultades en relación con la percepción y producción de las formas débiles de las palabras estructurales. En consecuencia, evaluamos la percepción y producción de las formas débiles y fuertes en nuestros alumnos, a través de una prueba de escucha y otra de habla, una vez que los estudiantes de primer año de la Facultad de Filosofía, Humanidades y Artes, Universidad Nacional de San Juan (UNSJ), habían finalizado el período de entrenamiento en estas formas. Para la recolección de datos utilizamos dos tipos de tests: uno de percepción y otro de producción. En general, los resultados corroboraron nuestra percepción: los alumnos continuaron teniendo mayor dificultad en la percepción y producción de las formas débiles de las palabras estructurales que en la de las formas fuertes, aún después de haber estado expuestos al entrenamiento explícito.