Dimension-independent Harnack inequalities for subordinated semigroups

Dimension-independent Harnack inequalities are derived for a class of subordinate semigroups. In particular, for a diffusion satisfying the Bakry-Emery curvature condition, the subordinate semigroup with power $\alpha$ satisfies a dimension-free Harnack inequality provided $\alpha \in(1/2, 1)$, and it satisfies the log-Harnack inequality for all $\alpha \in (0,1).$ Some infinite-dimensional examples are also presented

Safety of intracranial electroencephalography during functional electromagnetic resonance imaging in humans at 1.5 tesla using a head transmit RF coil: Histopathological and heat-shock immunohistochemistry observations.

Simultaneous intracranial EEG and functional MRI (icEEG-fMRI) recordings in humans, whereby EEG is recorded from electrodes implanted inside the cranium during fMRI scanning, were made possible following safety studies on test phantoms and our specification of a rigorous data acquisition protocol. In parallel with this work, other investigations in our laboratory revealed the damage caused by the EEG electrode implantation procedure at the cellular level. The purpose of this report is to further explore the safety of performing MRI, including simultaneous icEEG-fMRI data acquisitions, in the presence of implanted intra-cranial EEG electrodes, by presenting some histopathological and heat-shock immunopositive labeling observations in surgical tissue samples from patients who underwent the scanning procedure. We performed histopathology and heat shock protein expression analyses on surgical tissue samples from nine patients who had been implanted with icEEG electrodes. Three patients underwent icEEG-fMRI and structural MRI (sMRI); three underwent sMRI only, all at similar time points after icEEG implantation; and three who did not undergo functional or sMRI with icEEG electrodes. The histopathological findings from the three patients who underwent icEEG-fMRI were similar to those who did not, in that they showed no evidence of additional damage in the vicinity of the electrodes, compared to cases who had no MRI with implanted icEEG electrodes. This finding was similar to our observations in patients who only underwent sMRI with implanted icEEG electrodes. This work provides unique evidence on the safety of functional MRI in the presence of implanted EEG electrodes. In the cases studied, icEEG-fMRI performed in accordance with our protocol based on low-SAR (≤0.1 W/kg) sequences at 1.5T using a head-transmit RF coil, did not result in measurable additional damage to the brain tissue in the vicinity of implanted electrodes. Furthermore, while one cannot generalize the results of this study beyond the specific electrode implantation and scanning conditions described herein, we submit that our approach is a useful framework for the post-hoc safety assessment of MR scanning with brain implants. [Abstract copyright: Copyright © 2022. Published by Elsevier Inc.

Instrumental variable approaches to identifying the causal effect of educational attainment on dementia risk

PURPOSE: Education is an established correlate of cognitive status in older adulthood, but whether expanding educational opportunities would improve cognitive functioning remains unclear given limitations of prior studies for causal inference. Therefore, we conducted instrumental variable (IV) analyses of the association between education and dementia risk, using for the first time in this area, genetic variants as instruments as well as state-level school policies. METHODS: IV analyses in the Health and Retirement Study cohort (1998-2010) used two sets of instruments: (1) a genetic risk score constructed from three single-nucleotide polymorphisms (SNPs; n = 7981); and (2) compulsory schooling laws (CSLs) and state school characteristics (term length, student teacher ratios, and expenditures; n = 10,955). RESULTS: Using the genetic risk score as an IV, there was a 1.1% reduction in dementia risk per year of schooling (95% confidence interval, -2.4 to 0.02). Leveraging compulsory schooling laws and state school characteristics as IVs, there was a substantially larger protective effect (-9.5%; 95% confidence interval, -14.8 to -4.2). Analyses evaluating the plausibility of the IV assumptions indicated estimates derived from analyses relying on CSLs provide the best estimates of the causal effect of education. CONCLUSIONS: IV analyses suggest education is protective against risk of dementia in older adulthood

Bisphenol A exposure in Mexico City and risk of prematurity: a pilot nested case control study

Abstract Background Presence of Bisphenol A (BPA) has been documented worldwide in a variety of human biological samples. There is growing evidence that low level BPA exposure may impact placental tissue development and thyroid function in humans. The aim of this present pilot study was to determine urinary concentrations of BPA during the last trimester of pregnancy among a small subset of women in Mexico City, Mexico and relate these concentrations to risk of delivering prematurely. Methods A nested case-control subset of 60 participants in the Early Life Exposure in Mexico to ENvironmental Toxicants (ELEMENT) study in Mexico City, Mexico were selected based on delivering less than or equal to 37 weeks of gestation and greater than 37 weeks of gestation. Third trimester archived spot urine samples were analyzed by online solid phase extraction coupled with high performance liquid chromatography isotope dilution tandem mass spectrometry. Results BPA was detected in 80.0% (N = 48) of the urine samples; total concentrations ranged from < 0.4 μg/L to 6.7 μg/L; uncorrected geometric mean was 1.52 μg/L. The adjusted odds ratio of delivering less than or equal to 37 weeks in relation to specific gravity adjusted third trimester BPA concentration was 1.91 (95%CI 0.93, 3.91, p-value = 0.08). When cases were further restricted to births occurring prior to the 37th week (n = 12), the odds ratio for specific-gravity adjusted BPA was larger and statistically significant (p < 0.05). Conclusions This is the first study to document measurable levels of BPA in the urine of a population of Mexican women. This study also provides preliminary evidence, based on a single spot urine sample collected during the third trimester, that pregnant women who delivered less than or equal to 37 weeks of gestation and prematurely (< 37 weeks) had higher urinary concentrations of BPA compared to women delivering after 37 weeks.http://deepblue.lib.umich.edu/bitstream/2027.42/78251/1/1476-069X-9-62.xmlhttp://deepblue.lib.umich.edu/bitstream/2027.42/78251/2/1476-069X-9-62.pdfPeer Reviewe

China's great migration: the impact of the reduction in trade policy uncertainty

We analyze the effect of China's integration into the world economy on workers in the country and show that one important channel of impact has been internal migration. Specifically, we study the changes in internal migration rates triggered by the reduction in trade policy uncertainty faced by Chinese exporters in the U.S. This reduction is characterized by plausibly exogenous variation across sectors, which we use to construct a local measure of treatment, at the level of a Chinese prefecture, following Bartik (1991). This allows us to estimate a difference-in-difference empirical specification based on variation across Chinese prefectures before and after 2001. We find that prefectures facing the average decline in trade policy uncertainty experience an 18 percent increase in their internal in-migration rate this result is driven by migrants who are "non-hukou", skilled, and in their prime working age. Finally, in those prefectures, working hours of "native" unskilled workers significantly increase - while the employment rates of neither native workers nor internal migrants change

China's "Great Migration": the impact of the reduction in trade policy uncertainty

We analyze the effect of China's integration into the world economy on workers in the country and show that one important channel of impact has been internal migration. Specifically, we study the changes in internal migration rates triggered by the reduction in trade policy uncertainty faced by Chinese exporters in the U.S. This reduction is characterized by plausibly exogenous variation across products, which we use to construct a local measure of treatment, at the level of a Chinese prefecture, following Bartik (1991). This allows us to estimate a difference-in-difference empirical specification based on variation across Chinese prefectures before and after 2001. We find that prefectures facing the average decline in trade policy uncertainty experienced a 24 percent increase in their internal in-migration rate - this result is driven by migrants who are “non-hukou", skilled, and in their prime working age. Finally, in those prefectures, working hours of \native" unskilled workers significantly increased, and internal migrants found employment in the places they migrated to

China's great migration: the impact of the reduction in trade policy uncertainty

We analyze the effect of China's integration into the world economy on workers in the country and show that one important channel of impact has been internal migration. Specifically, we study the changes in internal migration rates triggered by the reduction in trade policy uncertainty faced by Chinese exporters in the U.S. This reduction is characterized by plausibly exogenous variation across sectors, which we use to construct a local measure of treatment, at the level of a Chinese prefecture, following Bartik (1991). This allows us to estimate a difference-in-difference empirical specification based on variation across Chinese prefectures before and after 2001. We find that prefectures facing the average decline in trade policy uncertainty experience an 18 percent increase in their internal in-migration rate this result is driven by migrants who are "non-hukou", skilled, and in their prime working age. Finally, in those prefectures, working hours of "native" unskilled workers significantly increase - while the employment rates of neither native workers nor internal migrants change