Migration Background and Educational Tracking: Is there a Double Disadvantage for Second-Generation Immigrants?

Research on immigrants’ educational disadvantages largely focuses on differences in student achievement tests. Exploiting data from the German PIRLS extension, we find that second-generation immigrants face additional disadvantages with respect to grades and teacher recommendations for secondary school tracks that cannot be explained by differences in student achievement tests and general intelligence. Second-generation immigrations are disproportionately affected by prevailing social inequalities at the transition to secondary school tracks due to their generally less favorable socio-economic background. We additionally provide new evidence suggesting that these inequalities might be related to the failing economic assimilation of immigrants.immigration, educational inequalities, educational tracking, Germany

Identity and Entrepreneurship

We incorporate the concept of social identity into a stylized model of occupational choice and analyze whether an individual’s identity affects his or her decision to become an entrepreneur. We argue that an entrepreneurial identity results from an individual’s socialization. This could be parental influence but, as argued in this paper, also peer influence. To test this empirically, we apply instrumental variable approaches to PISA data. Our findings suggest that having an entrepreneurial peer group has a positive effect on an individual’s entrepreneurial intentions. Regarding entrepreneurial parents, we find a positive effect that cannot only be explained by ownership succession of the family business.occupational choice, entrepreneurship, identity, peer effects

NL6, ein neuer monoklonaler Antikörper zur Analyse der O-Glycosylierung von Neurofilament Protein M

NL6 ist ein neuer monoklonaler Antikörper, der ein spezifische O-Glycosylierung auf Neurofilament Protein M erkennt. In der Arbeit wurde der Antikörper allgemein charakterisiert, das Epitop in der C-terminalen KSP Region von humanen NF-M identifiziert und die Expression und Verteilung der von NL6 erkannten Subpopulation von NF-M im Vergleich zu Gesamt-NF-M untersucht. Desweiteren wurden die Regulation dieser Glycosylierung analysiert und eine mögliche Anwendung des Antikörpers bei der Untersuchung von ALS und Diabetes diskutiert. Die Untersuchungen zeigten, dass NL6 ein interessanter und nützlicher Antikörper zur Analyse der O-Glycosylierung von NF-M darstellt, besonders im Hinblick auf eine veränderte Expression im ALS Tiermodell

Censored Quantile Regressions and the Length of Unemployment Periods in West Germany

In this paper, we estimate the effect of different macro and micro variables on thedistribution of unemployment duration in West Germany using censored quantile regressions. We analyze unemployment periods of more than 91,000 observations from the years 1981 to 1997 drawn from the IAB employment subsample. The latter is an administrative data set that is representative with respect to the socially insured workforce. Surprisingly, we find that the educational degree and variables indicating the macroeconomic environment such as the unemployment rate have a weak effect only. On the other hand, variables reflecting the (un-)employment history of an individual such as the length of tenure, recall to the same employer in the past, recent unemployment and the position in the population income distribution before unemployment have the strongest effects on unemployment duration. We conclude that work history variables are the ones most suitable in characterizing the unemployment duration of an individual. From a methodological point of view, it is interesting that some regression coefficients have a different sign depending on the quantiles of the unemployment duration distribution. This clearly is a violation of the classical proportional hazard assumption which is very common in unemployment duration analysis. --censored quantile regression,unemployment duration,administrative data

Censored Quantile Regressions and the Length of Unemployment Periods in West Germany

We apply censored quantile regressions to representative German register data with more than 91,000 observations in order to determine crucial factors that influence the distribution of unemployment duration in West Germany during the 1980s and 1990s. We find that the effect of some regressors varies and has different sign depending on the quantiles of the unemployment duration distribution – a violation of the classical proportional hazard assumption which is very popular in unemployment duration analysis. We also find that variables reflecting the (un-)employment history of an individual such as the length of tenure, recall to the same employer in the past, recent unemployment and the position in the population income distribution before unemployment have the strongest effects on unemployment duration. We conclude that work history variables are most suitable in characterizing the job search behavior of an individual. The macroeconomic environment and the educational degree seem to have a limited effect only. --censored quantile regression,unemployment duration,register data

Pressure-Induced Alterations in the Protein Pattern of the Thermophilic Archaebacterium Methanococcus thermolithotrophicus

Elevated hydrostatic pressure has been shown to affect the growth rate of the thermophilic methanobacterium Methanococcus thermolithotrophicus without extending its temperature range of viability. Analysis of the cell inventory after approximately 10 h of incubation at 65 degrees C and 50 MPa (applying high-pressure liquid chromatography and two-dimensional gel electrophoresis) proved that pressure induces alterations in the protein pattern and the amino acid composition of the total cell hydrolysate. Gels showed that after pressurization a series of (basic) proteins with a molecular mass in the range of 38 and 70 kilodaltons occurs which is not detectable in cells grown at normal atmospheric pressure. The question of whether the observed alterations are caused by the perturbation of the balance of protein synthesis and turnover or by the pressure-induced synthesis of compounds analogous to heat shock proteins remains unanswered

Diffusion in simple fluids

Computed self diffusion coefficients for the Lennard-Jones and hard sphere fluids are related by Dej = DNs(aB) exp (--e/2kB T) where σB=σLJ(2/[1+ii(1+2kBT/ε)])1/6, the effective hard sphere diameter, is the (average) distance of closest approach in collisions between molecules which interact with the positive part of the LJ potential, and the Arrhenius term reflects the influence of the negative part. σLJ and ε are the size and well depth parameters. Measured diffusion coefficients of the halomethane liquids are reproduced by the equation over wide ranges of temperature and density and do not reveal any influence of the inelastic effects associated with molecular anisotropy

Anomalien des flüssigen Wassers

Bei tiefen Temperaturen (T < 300 K) zeigt flüssiges Wasser viele ungewöhnliche physikalisch-chemische Eigenschaften, die durch die starke Direktivität der Wasserstoffbrückenbindung und die damit verbundene energetische Bevorzugung einer tetraedrischen Nahordnung mit schlechter Raumausfüllung verursacht werden. Diese Anomalien werden im metastabilen Bereich unterhalb der Schmelzdruckkurve wesentlich ausgeprägter. Im vorliegenden Beitrag werden die Experimentalbefunde anhand der neueren Theorien diskutiert und mit den Ergebnissen von Computer-Simulationen am kalten Wasser verglichen. Die Anomalien des Wassers, die sich z. B. im Dichtemaximum der flüssigen Phase oder in der Abnahme der Viskosität mit dem Druck manifestieren, sind auf den Bereich T < 300 K und p ≲ 200 MPa beschränkt. Bei diesen Drücken zeigt das unterkühlte Wasser mit fallender Temperatur ein ungewöhnliches Verhalten: Alle isobaren Eigenschaften deuten auf einen Phasenübergang bei T ≈ (TK − 50 K), dessen physikalische Natur noch nicht eindeutig beschrieben werden kann. Dieses Phänomen ist bis jetzt ausschließlich im flüssigen Wasser beobachtet worden. – Künftig wird man unterkühlte wäßrige Lösungen für kinetische Untersuchungen verwenden und dadurch den zugänglichen dynamischen Bereich der Untersuchung wäßriger Lösungen erheblich erweitern können

Simultaneous multislice acquisition with multi-contrast segmented EPI for separation of signal contributions in dynamic contrast-enhanced imaging

We present a method to efficiently separate signal in magnetic resonance imaging (MRI) into a base signal S0, representing the mainly T1-weighted component without T2*-relaxation, and its T2*-weighted counterpart by the rapid acquisition of multiple contrasts for advanced pharmacokinetic modelling. This is achieved by incorporating simultaneous multislice (SMS) imaging into a multi-contrast, segmented echo planar imaging (EPI) sequence to allow extended spatial coverage, which covers larger body regions without time penalty. Simultaneous acquisition of four slices was combined with segmented EPI for fast imaging with three gradient echo times in a preclinical perfusion study. Six female domestic pigs, German-landrace or hybrid-form, were scanned for 11 minutes respectively during administration of gadolinium-based contrast agent. Influences of reconstruction methods and training data were investigated. The separation into T1- and T2*-dependent signal contributions was achieved by fitting a standard analytical model to the acquired multi-echo data. The application of SMS yielded sufficient temporal resolution for the detection of the arterial input function in major vessels, while anatomical coverage allowed perfusion analysis of muscle tissue. The separation of the MR signal into T1- and T2*-dependent components allowed the correction of susceptibility related changes. We demonstrate a novel sequence for dynamic contrast-enhanced MRI that meets the requirements of temporal resolution (Δt &lt; 1.5 s) and image quality. The incorporation of SMS into multi-contrast, segmented EPI can overcome existing limitations of dynamic contrast enhancement and dynamic susceptibility contrast methods, when applied separately. The new approach allows both techniques to be combined in a single acquisition with a large spatial coverage