Three Essays Considering The Labor Market Behavior Of Young Workers

This dissertation consists of three chapters investigating labor market trends, specifically of young workers (ages 18-24). In the United States, young workers decreased their labor market participation by more than 8\% from 1994-2014 and the first chapter of this research considers changing demographics and educational decisions to account for this decline. Using connected monthly Current Population Survey (CPS) data, an alternative definition of labor market attachment is considered, which accounts for attached, marginally attached, and not attached workers. Additionally, attending college is considered as a weak form of labor market participation. Accounting for demographic changes and varying levels of attachment by demographics, the decrease in the participation rate is decomposed into genuine and demographic changes. The finding is a genuine decrease of 1.5\% young workers out of the labor force over the twenty year period studied. A calculation of the impact of college major choice on participation is estimated by extending the decomposition, as well as estimating a logit model on participation by college major. For males certain majors (Agriculture and English and Foreign Language) correlate with lower labor force attachment, while others (Engineering, Mathematics, and Visual and Performing Arts) correspond with higher attachment. For females, graduate degrees are the strongest indicator of attachment to the labor force and being married correlates with non-attachment to the labor force. The second chapter of this research investigates the movement of young workers between labor market statuses. Rather than consider the stocks and percentages of workers in each state (i.e. charting the unemployment or participation rate), this paper analyzes the flows between statuses. A contribution of this research is to consider how labor market flows are impacted by education decisions by including schooling as a labor market status. Additionally, this chapter estimates the impact that labor market movements by young workers have on fluctuations of their unemployment rate; flows between unemployment and not-in-the-labor-force, account for over forty percent of the variation in unemployment for young workers. As young workers decide whether to participate in the labor force or continue their education, they must decide whether to forgo ``on-the-job” training and experience or attend college to acquire human capital through formal education. Following the work of John Robst (2007), the third chapter of this research considers three questions: To what extent do college graduates work in fields unrelated to their most recent degree field? Which degree fields lead to greater mismatch? What is the relationship between working outside a degree field and wages? This research first provides updated answers to these questions using data from the 2013 National Survey of College Graduates (NSCG). Additionally, this work includes new specifications of the wage penalty using parental education level, which was unavailable in Robst's data. The result indicates a wage correlation of complete mismatch between job and college major that is more than three times that of a partial mismatch. An important contribution of this paper is to address changes over time by comparing results from the NSCG data in 1993, 2003, 2010, and 2013. A significant result is that the negative association between mismatch and wages has increased by a factor of three for men and over four times for women from 1993 to 2013. The conclusions in this research describe both structural and cyclical trends in the young worker labor market. Despite the significant proportion of young workers in the labor force, little research has been conducted using data from individuals under the age of twenty-five. This dissertation focuses on young workers because of the importance they play in the labor market, but also to motivate future research. The decisions young people make impact the labor market as well as drive individual future labor market outcomes; policy should be informed by the structural and cyclical trends presented throughout this research.Economic

Computational and informatics strategies for identification of specific protein interaction partners in affinity purification mass spectrometry experiments

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92060/1/pmic7070.pd

The power of protein interaction networks for associating genes with diseases

Motivation: Understanding the association between genetic diseases and their causal genes is an important problem concerning human health. With the recent influx of high-throughput data describing interactions between gene products, scientists have been provided a new avenue through which these associations can be inferred. Despite the recent interest in this problem, however, there is little understanding of the relative benefits and drawbacks underlying the proposed techniques

Recessive mutations in POLR1C cause a leukodystrophy by impairing biogenesis of RNA polymerase III

Contains fulltext : 153818.pdf (publisher's version ) (Open Access)A small proportion of 4H (Hypomyelination, Hypodontia and Hypogonadotropic Hypogonadism) or RNA polymerase III (POLR3)-related leukodystrophy cases are negative for mutations in the previously identified causative genes POLR3A and POLR3B. Here we report eight of these cases carrying recessive mutations in POLR1C, a gene encoding a shared POLR1 and POLR3 subunit, also mutated in some Treacher Collins syndrome (TCS) cases. Using shotgun proteomics and ChIP sequencing, we demonstrate that leukodystrophy-causative mutations, but not TCS mutations, in POLR1C impair assembly and nuclear import of POLR3, but not POLR1, leading to decreased binding to POLR3 target genes. This study is the first to show that distinct mutations in a gene coding for a shared subunit of two RNA polymerases lead to selective modification of the enzymes' availability leading to two different clinical conditions and to shed some light on the pathophysiological mechanism of one of the most common hypomyelinating leukodystrophies, POLR3-related leukodystrophy

ROCS: a reproducibility index and confidence score for interaction proteomics

Affinity-Purification Mass-Spectrometry (AP-MS) provides a powerful means of identifying protein complexes and interactions. Several important challenges exist in interpreting the results of AP-MS experiments. First, the reproducibility of AP-MS experimental replicates can be low, due both to technical variability and the dynamic nature of protein interactions in the cell. Second, the identification of true protein-protein interactions in AP-MS experiments is subject to inaccuracy due to high false negative and false positive rates. Several experimental approaches can be used to mitigate these drawbacks, including the use of replicated and control experiments and relative quantification to sensitively distinguish true interacting proteins from false ones. RESULTS: To address the issues of reproducibility and accuracy of protein-protein interactions, we introduce a two-step method, called ROCS, which makes use of Indicator Proteins to select reproducible AP-MS experiments, and of Confidence Scores to select specific protein-protein interactions. The Indicator Proteins account for measures of protein identification as well as protein reproducibility, effectively allowing removal of outlier experiments that contribute noise and affect downstream inferences. The filtered set of experiments is then used in the Protein-Protein Interaction (PPI) scoring step. Prey protein scoring is done by computing a Confidence Score, which accounts for the probability of occurrence of prey proteins in the bait experiments relative to the control experiment, where the significance cutoff parameter is estimated by simultaneously controlling false positives and false negatives against metrics of false discovery rate and biological coherence respectively. In summary, the ROCS method relies on automatic objective criterions for parameter estimation and error-controlled procedures. We illustrate the performance of our method by applying it to five previously published AP-MS experiments, each containing well characterized protein interactions, allowing for systematic benchmarking of ROCS. We show that our method may be used on its own to make accurate identification of specific, biologically relevant protein-protein interactions or in combination with other AP-MS scoring methods to significantly improve inferences. CONCLUSIONS: Our method addresses important issues encountered in AP-MS datasets, making ROCS a very promising tool for this purpose, either on its own or especially in conjunction with other methods. We anticipate that our methodology may be used more generally in proteomics studies and databases, where experimental reproducibility issues arise. The method is implemented in the R language, and is available as an R package called "ROCS", freely available from the CRAN repository http://cran.r-project.org/

Evolution of mechanical properties of lava dome rocks across the Soufrière Hills eruption, and application in discrete element models

&amp;lt;p&amp;gt;Lava dome collapses pose a hazard to surrounding populations, but equally represent important processes for deciphering the eruptive history of a volcano. Models examining lava dome instability rely on accurate physical and mechanical properties of volcanic rocks. Here we focus on determining the physical and mechanical properties of a suite of temporally-constrained rocks from different phases of the 1995&amp;amp;#8211;2010 eruption at Soufri&amp;amp;#232;re Hills volcano in Montserrat. We determine the uniaxial compressive strength, tensile strength, density, porosity, permeability, and Young&amp;amp;#8217;s modulus using laboratory measurements, complemented by Schmidt hammer testing in the field.&amp;lt;/p&amp;gt; &amp;lt;p&amp;gt;By viewing a snapshot of each phase, we find the highest tensile and compressive strengths in the samples attributed to Phase 4, corresponding to a lower permeability and an increasing proportion of isolated porosity. Samples from Phase 5 show lower compressive and tensile strengths, corresponding to the highest permeability and porosity of the tested materials. Overall, this demonstrates a reliance of mechanical properties primarily on porosity, however, a shift toward increasing prevalence of pore connectivity in weaker samples identified by microtextural analysis demonstrates that here pore connectivity also contributes to the strength and Young&amp;amp;#8217;s Modulus, as well as controlling permeability. The range in UCS strengths are supported using Schmidt hammer field testing. We determine a narrow range in mineralogy across the sample suite, but identify a correlation between increasing crystallinity and increasing strength. We correlate these changes to residency-time in the growing lava dome during the eruption, where stronger rocks have undergone more crystallization. In addition, subsequent recrystallization of silica polymorphs from the glass phase may further strengthen the material.&amp;lt;/p&amp;gt; &amp;lt;p&amp;gt;We incorporate the variation in physical and mechanical rock properties shown within the Soufri&amp;amp;#232;re Hills eruptive into structural stability models of the remaining over-steepened dome on Montserrat, considering also the possible effect of upscaling on the edifice-scale rock properties, and the resultant dome stability.&amp;lt;/p&amp;gt;</jats:p

Evolution of mechanical properties of lava dome rocks across the Soufri&amp;#232;re Hills eruption, and application in discrete element models

&amp;lt;p&amp;gt;Lava dome collapses pose a hazard to surrounding populations, but equally represent important processes for deciphering the eruptive history of a volcano. Models examining lava dome instability rely on accurate physical and mechanical properties of volcanic rocks. Here we focus on determining the physical and mechanical properties of a suite of temporally-constrained rocks from different phases of the 1995&amp;amp;#8211;2010 eruption at Soufri&amp;amp;#232;re Hills volcano in Montserrat. We determine the uniaxial compressive strength, tensile strength, density, porosity, permeability, and Young&amp;amp;#8217;s modulus using laboratory measurements, complemented by Schmidt hammer testing in the field.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;By viewing a snapshot of each phase, we find the highest tensile and compressive strengths in the samples attributed to Phase 4, corresponding to a lower permeability and an increasing proportion of isolated porosity. Samples from Phase 5 show lower compressive and tensile strengths, corresponding to the highest permeability and porosity of the tested materials. Overall, this demonstrates a reliance of mechanical properties primarily on porosity, however, a shift toward increasing prevalence of pore connectivity in weaker samples identified by microtextural analysis demonstrates that here pore connectivity also contributes to the strength and Young&amp;amp;#8217;s Modulus, as well as controlling permeability. The range in UCS strengths are supported using Schmidt hammer field testing. We determine a narrow range in mineralogy across the sample suite, but identify a correlation between increasing crystallinity and increasing strength. We correlate these changes to residency-time in the growing lava dome during the eruption, where stronger rocks have undergone more crystallization. In addition, subsequent recrystallization of silica polymorphs from the glass phase may further strengthen the material.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;We incorporate the variation in physical and mechanical rock properties shown within the Soufri&amp;amp;#232;re Hills eruptive into structural stability models of the remaining over-steepened dome on Montserrat, considering also the possible effect of upscaling on the edifice-scale rock properties, and the resultant dome stability.&amp;lt;/p&amp;gt; </jats:p