Production of two hadrons in semi-inclusive Deep Inelatic Scattering

We present the general expression, in terms of structure functions, of the cross section for the production of two hadrons in semi-inclusive deep-inelastic scattering. We analyze this process including full transverse-momentum dependence up to subleading twist and check, where possible, the consistency with existing literature.Comment: 14 pages, 1 figur

The intrinsic value of HFO features as a biomarker of epileptic activity

High frequency oscillations (HFOs) are a promising biomarker of epileptic brain tissue and activity. HFOs additionally serve as a prototypical example of challenges in the analysis of discrete events in high-temporal resolution, intracranial EEG data. Two primary challenges are 1) dimensionality reduction, and 2) assessing feasibility of classification. Dimensionality reduction assumes that the data lie on a manifold with dimension less than that of the feature space. However, previous HFO analyses have assumed a linear manifold, global across time, space (i.e. recording electrode/channel), and individual patients. Instead, we assess both a) whether linear methods are appropriate and b) the consistency of the manifold across time, space, and patients. We also estimate bounds on the Bayes classification error to quantify the distinction between two classes of HFOs (those occurring during seizures and those occurring due to other processes). This analysis provides the foundation for future clinical use of HFO features and buides the analysis for other discrete events, such as individual action potentials or multi-unit activity.Comment: 5 pages, 5 figure

Transverse Target Moments of SIDIS Vector Meson Production at HERMES

The on-going analysis of the transverse target ( A UT ) moments of the non-collinear cross section for SIDIS dihadron production at Hermes is discussed. These moments access the transversity ( h 1 ), pretzelocity ( h _ 1T ), and Sivers ( f _ 1T ) distribution functions convoluted with the unpolarized ( D 1 ) and Collins ( H 1 ) dihadron fragmentation functions. This measurement allows greater insight into the flavor decomposition and factorization of these functions. Additionally, the results will test the Lund/Artru fragmentation model, which predicts a sign change in the Collins function between pseudo-scalar mesons and certain partial waves of vector mesons. In preparation for this analysis, a new Monte Carlo generator has been written, and non-collinear fragmentation functions have been computed in a spectator model. Additionally, an alternate partial wave expansion is presented, providing a complementary interpretation of the fragmentation functions and allowing computation of the next-to-leading twist cross section.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90826/1/1742-6596_295_1_012044.pd

Differential Effects of a Military Parenting Program on Child Internalizing and Externalizing Behavior: A Latent Profile Analysis

University of Minnesota Ph.D. dissertation. December 2017. Major: Family Social Science. Advisor: Abigail Gewirtz. 1 computer file (PDF); vi, 74 pages.Some children who experience a parental deployment evince high rates of internalizing and externalizing behavior in the years following that parent’s return home. This dissertation explored the risk for mental health symptoms in military children in the years following a parent’s deployment, as well as the risk factors and outcomes associated with different profile membership. In the first phase, I studied heterogeneity in children’s internalizing symptoms and externalizing behavior among 336 military youth who experienced a parental deployment since 2001 using a finite number of discrete mental health profiles with latent profile analysis (LPA), as well as risk factors associated with membership to different risk profiles. Results indicated that current parental mental health problems were associated with child membership in the higher risk profile relative to the low risk profile, but that deployment was not significantly associated with profile membership. In the second phase, I assessed whether parent assignment to a preventive parenting intervention developed for military families, After Deployment Adaptive Parenting Tools intervention (ADAPT; Gewirtz, Pinna, Hanson, & Brockberg, 2014) was associated with improvement in child internalizing and externalizing behavior at one year follow-up, and whether differential treatment effects emerged according to a child’s mental health profile at baseline. Results showed significantly lower anxiety and conduct problems for the intervention group relative to the control group that differed according to baseline profile membership

Estimation of circular statistics in the presence of measurement bias

Background and objective. Circular statistics and Rayleigh tests are important tools for analyzing the occurrence of cyclic events. However, current methods fail in the presence of measurement bias, such as incomplete or otherwise non-uniform sampling. Consider, for example, studying 24-cyclicity but having data not recorded uniformly over the full 24-hour cycle. The objective of this paper is to present a method to estimate circular statistics and their statistical significance even in this circumstance. Methods. We present our objective as a special case of a more general problem: estimating probability distributions in the context of imperfect measurements, a highly studied problem in high energy physics. Our solution combines 1) existing approaches that estimate the measurement process via numeric simulation and 2) innovative use of linear parametrizations of the underlying distributions. We compute the estimation error for several toy examples as well as a real-world example: analyzing the 24-hour cyclicity of an electrographic biomarker of epileptic tissue controlled for state of vigilance. Results. Our method shows low estimation error. In a real-world example, we observed the corrected moments had a root mean square residual less than 0.007. We additionally found that, even with unfolding, Rayleigh test statistics still often underestimate the p-values (and thus overestimate statistical significance) in the presence of non-uniform sampling. Numerical estimation of statistical significance, as described herein, is thus preferable. Conclusions. The presented methods provide a robust solution to addressing incomplete or otherwise non-uniform sampling. The general method presented is also applicable to a wider set of analyses involving estimation of the true probability distribution adjusted for imperfect measurement processes

Preictal variability of high‐frequency oscillation rates in refractory epilepsy

ObjectiveHigh‐frequency oscillations (HFOs) have shown promising utility in the spatial localization of the seizure onset zone for patients with focal refractory epilepsy. Comparatively few studies have addressed potential temporal variations in HFOs, or their role in the preictal period. Here, we introduce a novel evaluation of the instantaneous HFO rate through interictal and peri‐ictal epochs to assess their usefulness in identifying imminent seizure onset.MethodsUtilizing an automated HFO detector, we analyzed intracranial electroencephalographic data from 30 patients with refractory epilepsy undergoing long‐term presurgical evaluation. We evaluated HFO rates both as a 30‐minute average and as a continuous function of time and used nonparametric statistical methods to compare individual and population‐level differences in rate during peri‐ictal and interictal periods.ResultsMean HFO rate was significantly higher for all epochs in seizure onset zone channels versus other channels. Across the 30 patients of our cohort, we found no statistically significant differences in mean HFO rate during preictal and interictal epochs. For continuous HFO rates in seizure onset zone channels, however, we found significant population‐wide increases in preictal trends relative to interictal periods. Using a data‐driven analysis, we identified a subset of 11 patients in whom either preictal HFO rates or their continuous trends were significantly increased relative to those of interictal baseline and the rest of the population.SignificanceThese results corroborate existing findings that HFO rates within epileptic tissue are higher during interictal periods. We show this finding is also present in preictal, ictal, and postictal data, and identify a novel biomarker of preictal state: an upward trend in HFO rate leading into seizures in some patients. Overall, our findings provide preliminary evidence that HFOs can function as a temporal biomarker of seizure onset.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163961/1/epi16680.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163961/2/epi16680_am.pd

Transverse Target Moments of Dihadron Production in Semi-inclusive Deep Inelastic Scattering at HERMES.

Pseudo-scalar meson production in semi-inclusive deep inelastic scattering (SIDIS) at HERMES has provided essential information towards the understanding of the transverse momentum dependent structure of the proton. SIDIS dihadron (hadron pair) production also provides access to the structure of the proton and is complimentary to that provided by pseudo-scalars production, as the same parton distribution functions are involved. For example, while pion and kaon final states allow access to flavor combinations of the Sivers distribution function, SIDIS $phi$ meson production (included in the $K^+K^-$ dihadron sample) allows direct access to the Sivers function for the strange quarks. The Sivers function for strange quarks is also related to the orbital angular momentum of the gluons. In the SIDIS cross section, the distribution functions are integrated with fragmentation functions for the respective final states. These fragmentation functions yield information regarding the quark hadronization process. Of particular interest, the Lund/Artru model of fragmentation makes specific predictions regarding the relation between results for dihadron and pseudo-scalar meson production for certain transverse momentum dependent moments. This dissertation presents the first transverse momentum dependent (non-collinear) analysis of the transverse target moments in SIDIS dihadron production, extracting results from the 2002-2005 HERMES data set for $pi^+pi^0$, $pi^+pi^-$, $pi^-pi^0$ and $K^+K^-$ dihadrons. A new transverse momentum dependent Monte Carlo generator, TMDGen, is also introduced. Additionally, several theoretical developments have been completed, including a new partial wave analysis of the fragmentation functions, computation of the next-to-leading twist dihadron cross section, and the first model calculation for transverse momentum dependent dihadron fragmentation functions.PhDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/86394/1/sgliske_1.pd

Regge and Okamoto symmetries

We will relate the surprising Regge symmetry of the Racah-Wigner 6j symbols to the surprising Okamoto symmetry of the Painleve VI differential equation. This then presents the opportunity to give a conceptual derivation of the Regge symmetry, as the representation theoretic analogue of the author's previous derivation of the Okamoto symmetry. [The resulting derivation is quite simple, so it would be surprising if it has not been previously observed. Any references would be appreciated!]Comment: 14 page