1,243 research outputs found

    A Structural Model of Tenure and Specific Investments

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    Though a lot of work has been done on the distribution of job tenures, we are still uncertain about its main determinants. In this paper, we stress random shocks to match productivity after the start of an employment relation. The specificity of investment makes hiring and separation decisions irreversible.These decisions therefore have an option value. Assumptions on riskneutrality, efficient bargaining, and the efficient resolution of hold up problems allow investment and separation decisions to be analyzed separately from wage setting. The tenure profiles in wages implied by the model fit the observed pattern quite well. The model yields a hump shaped pattern in separation rates, similar to learning models, but with a slowerdecline after the peak. Estimation results using job tenure data from the NLSY support this humped shaped pattern and favor this model above the learning model. We develop a methodology to analyze the decomposition of shocks to match productivity into idiosyncratic and macro-level shocks.When assuming a Last-In-First-Out (LIFO) separation rule, this model of individualemployment relations is embedded in a model of firm level employment, that satisfies Gibrat’s law. The LIFO rule is interpreted as an institution protecting the property rights on specific investments of incumbentworkers against hiring new workers by the firm.option value, job tenure, tenure profiles

    Direct detection of methylation in genomic DNA

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    The identification of methylated sites on bacterial genomic DNA would be a useful tool to study the major roles of DNA methylation in prokaryotes: distinction of self and nonself DNA, direction of post-replicative mismatch repair, control of DNA replication and cell cycle, and regulation of gene expression. Three types of methylated nucleobases are known: N(6)-methyladenine, 5-methylcytosine and N(4)-methylcytosine. The aim of this study was to develop a method to detect all three types of DNA methylation in complete genomic DNA. It was previously shown that N(6)-methyladenine and 5-methylcytosine in plasmid and viral DNA can be detected by intersequence trace comparison of methylated and unmethylated DNA. We extended this method to include N(4)-methylcytosine detection in both in vitro and in vivo methylated DNA. Furthermore, application of intersequence trace comparison was extended to bacterial genomic DNA. Finally, we present evidence that intrasequence comparison suffices to detect methylated sites in genomic DNA. In conclusion, we present a method to detect all three natural types of DNA methylation in bacterial genomic DNA. This provides the possibility to define the complete methylome of any prokaryote

    Bonding bare die LEDs on PET foils for lighting applications: thermal design modeling and bonding experiments

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    Integration of LEDs on flexible foil substrates is of interest for flexible lighting applications and flexible photonic devices. A matrix of LEDs on a foil combined with a diffuser can be a potential alternative for flexible OLED lighting devices. Preferably, these LEDs are integrated in an unpackaged, bare die form as it reduces cost, footprint and thickness. As a substrate, preferably low cost materials like polyesters (PET) are being used, especially for large area devices. However, the use of these materials imposes some limitations. Most notably, the low temperature stability (<100 degrees C continuous use temperature) of these materials limits the maximum temperatures during the manufacturing process and poses constraints on the thermal design of the device. The current paper describes the results of research on possibilities for integrating bare die LEDs with low cost flexible PET foils. Finite element (FE) thermal modeling has been performed of possible designs of adhesively bonded LED-on-foil and laminated LED-in-foil configurations. The role of the different materials and the effect of their geometries on the temperature distribution in the simulated devices are discussed. The results give insight in measures that can be taken to keep the temperature of all the components of the device within operational limits. For LEDs bonded on Cu-PET foil the modeled temperature distributions are compared to experimentally observed temperature distributions in LED on PET foil reference devices using infrared thermal imaging. Besides this, initial studies on directly bonding LEDs on etched Cu on PET substrates using anisotropic conducting adhesives and isotropic conducting adhesives were performed. An experimental comparison is made between the different techniques based on temperature/humidity reliability and flexural stability of the bonded LEDs, based on these preliminary results

    Effect of Systolic Blood Pressure on Left Ventricular Structure and Function A Mendelian Randomization Study

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    We aimed to estimate the effects of a lifelong exposure to high systolic blood pressure (SBP) on left ventricular (LV) structure and function using Mendelian randomization. A total of 5596 participants of the UK Biobank were included for whom cardiovascular magnetic resonance imaging and genetic data were available. Major exclusion criteria included nonwhite ethnicity, major cardiovascular disease, and body mass index >30 o
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