344 research outputs found
On Recoding Ordered Treatments as Binary Indicators
Researchers using instrumental variables to investigate the effects of
ordered treatments (e.g., years of education, months of healthcare coverage)
often recode treatment into a binary indicator for any exposure (e.g., any
college, any healthcare coverage). The resulting estimand is difficult to
interpret unless the instruments only shift compliers from no treatment to some
positive quantity and not from some treatment to more -- i.e., there are
extensive margin compliers only (EMCO). When EMCO holds, recoded endogenous
variables capture a weighted average of treatment effects across complier
groups that can be partially unbundled into each group's treated and untreated
means. Invoking EMCO along with the standard Local Average Treatment Effect
assumptions is equivalent to assuming choices are determined by a simple
two-factor selection model in which agents first decide whether to participate
in treatment at all and then decide how much. The instruments must only impact
relative utility in the first step. Although EMCO constrains unobserved
counterfactual choices, it places testable restrictions on the joint
distribution of outcomes, treatments, and instruments
Family Formation and Crime
The article of record as published may be found at�https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4198344We use administrative data from Washington State to perform a large-scale analysis of the impact of family formation on crime. Our estimates indicate that pregnancy triggers sharp declines in arrests rivaling any known intervention, supporting the view that childbirth is a 'turning point' that reduces deviant behavior through social bonds. For mothers, criminal arrests drop precipitously in the first few months of pregnancy, stabilizing at half of pre-pregnancy levels three years after birth. Men show a sustained 20 percent decline in crime that begins at pregnancy, although arrests for domestic violence spike at birth. These effects are concentrated among first-time parents, suggesting that a permanent change in preferences---rather than transitory time and budget shocks---may be responsible. A separate design using parents of stillborn children to estimate counterfactual arrest rates reinforces the main findings. Marriage, in contrast, is not associated with any sudden changes and marks the completion of a gradual 50 percent decline in arrests for both men and women
A Discrimination Report Card
We develop an Empirical Bayes grading scheme that balances the
informativeness of the assigned grades against the expected frequency of
ranking errors. Applying the method to a massive correspondence experiment, we
grade the racial biases of 97 U.S. employers. A four-grade ranking limits the
chances that a randomly selected pair of firms is mis-ranked to 5% while
explaining nearly half of the variation in firms' racial contact gaps. The
grades are presented alongside measures of uncertainty about each firm's
contact gap in an accessible rubric that is easily adapted to other settings
where ranks and levels are of simultaneous interest
Call to Action: The Impact of Cyberbullying in the COVID Era
Given the recent COVID-19 pandemic, research suggests that students are spending an increased amount of time online. Consequently, the opportunity for students engaged in, or students who are a victim of cyberbullying has increased as well. Bullying no longer begins and ends with the school bells, it has infiltrated every aspect of students’ lives through the internet. Similarly, to bullying, cyberbullying leads to negative outcomes; the purpose of this article is to identify support, prevention, and intervention suggestions for parents, educators and schools, and mental health providers to decrease students’ cyberbullying involvement
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Anomalous porosity preservation and preferential accumulation of gas hydrate in the Andaman accretionary wedge, NGHP-01 site 17A
In addition to well established properties that control the presence or absence of the hydrate stability zone, such as pressure, temperature, and salinity, additional parameters appear to influence the concentration of gas hydrate in host sediments. The stratigraphic record at Site 17A in the Andaman Sea, eastern Indian Ocean, illustrates the need to better understand the role pore-scale phenomena play in the distribution and presence of marine gas hydrates in a variety of subsurface settings. In this paper we integrate field-generated datasets with newly acquired sedimentology, physical property, imaging and geochemical data with mineral saturation and ion activity products of key mineral phases such as amorphous silica and calcite, to document the presence and nature of secondary precipitates that contributed to anomalous porosity preservation at Site 17A in the Andaman Sea. This study demonstrates the importance of grain-scale subsurface heterogeneities in controlling the occurrence and distribution of concentrated gas hydrate accumulations in marine sediments, and document the importance that increased permeability and enhanced porosity play in supporting gas concentrations sufficient to support gas hydrate formation. The grain scale relationships between porosity, permeability, and gas hydrate saturation documented at Site 17A likely offer insights into what may control the occurrence and distribution of gas hydrate in other sedimentary settings.This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/marine-and-petroleum-geologyKeywords: Indian Ocean, Porosity, Saturation, Gas hydrate, Grain size, Carbonate, Permeability, Volcanic as
Production of 3,4-dihydroxy L-phenylalanine by a newly isolated Aspergillus niger and parameter significance analysis by Plackett-Burman design
Production of 3,4-dihydroxy L-phenylalanine by a newly isolated Aspergillus niger and parameter significance analysis by Plackett-Burman design
<p>Abstract</p> <p>Background</p> <p>The amino acid derivative 3,4-dihydroxy L-phenylalanine (L-dopa) is gaining interest as a drug of choice for Parkinson's disease. <it>Aspergillus oryzae </it>is commonly used for L-dopa production; however, a slower growth rate and relatively lower tyrosinase activity of mycelia have led to an increasing interest in exploiting alternative fungal cultures. In the present investigation, we report on the microbiological transformation of L-tyrosine to L-dopa accomplished by a newly isolated filamentous fungus <it>Aspergillus niger</it>.</p> <p>Results</p> <p>The culture <it>A. niger </it>(isolate GCBT-8) was propagated in 500 ml Erlenmeyer flasks and the pre-grown mycelia (48 h old) were used in the reaction mixture as a source of enzyme tyrosinase. Grinded mycelia gave 1.26 fold higher L-dopa production compared to the intact at 6% glucose (pH 5.5). The rate of L-tyrosine consumption was improved from 0.198 to 0.281 mg/ml. Among the various nitrogen sources, 1.5% peptone, 1% yeast extract and 0.2% ammonium chloride were optimized. The maximal L-dopa was produced (0.365 mg/ml) at 0.3% potassium dihydrogen phosphate with L-tyrosine consumption of 0.403 mg/ml.</p> <p>Conclusion</p> <p>Over ~73% yield was achieved (degree of freedom 3) when the process parameters were identified using 2k-Plackett-Burman experimental design. The results are highly significant (p ≤ 0.05) and mark the commercial utility (LSD 0.016) of the mould culture which is perhaps the first ever report on L-dopa production from <it>A. niger</it>.</p
Bax regulates c-Myc-induced mammary tumour apoptosis but not proliferation in MMTV-c-myc transgenic mice
Methylated H3K4, a Transcription-Associated Histone Modification, Is Involved in the DNA Damage Response Pathway
Eukaryotic genomes are associated with a number of proteins such as histones that constitute chromatin. Post-translational histone modifications are associated with regulatory aspects executed by chromatin and all transactions on genomic DNA are dependent on them. Thus, it will be relevant to understand how histone modifications affect genome functions. Here we show that the mono ubiquitylation of histone H2B and the tri-methylation of histone H3 on lysine 4 (H3K4me3), both known for their involvement in transcription, are also important for a proper response of budding yeast cells to DNA damaging agents and the passage through S-phase. Cells that cannot methylate H3K4 display a defect in double-strand break (DSB) repair by non-homologous end joining. Furthermore, if such cells incur DNA damage or encounter a stress during replication, they very rapidly lose viability, underscoring the functional importance of the modification. Remarkably, the Set1p methyltransferase as well as the H3K4me3 mark become detectable on a newly created DSB. This recruitment of Set1p to the DSB is dependent on the presence of the RSC complex, arguing for a contribution in the ensuing DNA damage repair process. Taken together, our results demonstrate that Set1p and its substrate H3K4me3, which has been reported to be important for the transcription of active genes, also plays an important role in genome stability of yeast cells. Given the high degree of conservation for the methyltransferase and the histone mark in a broad variety of organisms, these results could have similar implications for genome stability mechanisms in vertebrate and mammalian cells
Large-Scale Phenotyping of an Accurate Genetic Mouse Model of JNCL Identifies Novel Early Pathology Outside the Central Nervous System
Cln3Δex7/8 mice harbor the most common genetic defect causing juvenile neuronal ceroid lipofuscinosis (JNCL), an autosomal recessive disease involving seizures, visual, motor and cognitive decline, and premature death. Here, to more thoroughly investigate the manifestations of the common JNCL mutation, we performed a broad phenotyping study of Cln3Δex7/8 mice. Homozygous Cln3Δex7/8 mice, congenic on a C57BL/6N background, displayed subtle deficits in sensory and motor tasks at 10–14 weeks of age. Homozygous Cln3Δex7/8 mice also displayed electroretinographic changes reflecting cone function deficits past 5 months of age and a progressive decline of retinal post-receptoral function. Metabolic analysis revealed increases in rectal body temperature and minimum oxygen consumption in 12–13 week old homozygous Cln3Δex7/8mice, which were also seen to a lesser extent in heterozygous Cln3Δex7/8 mice. Heart weight was slightly increased at 20 weeks of age, but no significant differences were observed in cardiac function in young adults. In a comprehensive blood analysis at 15–16 weeks of age, serum ferritin concentrations, mean corpuscular volume of red blood cells (MCV), and reticulocyte counts were reproducibly increased in homozygous Cln3Δex7/8 mice, and male homozygotes had a relative T-cell deficiency, suggesting alterations in hematopoiesis. Finally, consistent with findings in JNCL patients, vacuolated peripheral blood lymphocytes were observed in homozygous Cln3Δex7/8 neonates, and to a greater extent in older animals. Early onset, severe vacuolation in clear cells of the epididymis of male homozygous Cln3Δex7/8 mice was also observed. These data highlight additional organ systems in which to study CLN3 function, and early phenotypes have been established in homozygous Cln3Δex7/8 mice that merit further study for JNCL biomarker development
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