Correcting for Frequency Drift in Clinical Brain MR Spectroscopy.

PURPOSE: Averaging multiple repetitions to improve signal-to-noise ratio is common practice in magnetic resonance spectroscopy (MRS). However, temporal variations in scanner B0 due to motion or gradient heating may cause spectra to become misaligned, broadening and distorting peaks and impacting on processing and quantification. We present a comparison using in vivo data of different methods for correcting these errors. METHODS: Three different correction methods were applied to 53 brain scans: residual water peak alignment, creatine fitting, and spectral registration. In 32 of 53 subjects, diffusion tensor imaging (DTI) was acquired prior to the MRS scan. We compared the resulting linewidths to find the most effective technique. In addition, the impact on metabolite concentration estimates was evaluated. RESULTS: MRS data acquired after DTI imaging exhibited a frequency drift four times higher than data without DTI, resulting in changes to metabolite concentrations, particularly glutamate/glutamine. All three correction methods produced significantly improved linewidths relative to uncorrected data, with spectral registration performing best by a small margin. CONCLUSION: Frequency correction is an important step in processing MRS data, significantly impacting metabolite quantification, particularly after echo-planar imaging that often occurs with MRS scans in clinical studies. Spectral registration proved most effective at frequency correction.

Exclusive breastfeeding and maternal self-efficacy among women of intimate partner violence situations / Lactancia materna exclusiva y autoeficacia materna entre mujeres em situaciones de violencia em la pareja / Aleitamento materno exclusivo e autoeficácia materna entre mulheres em situação de violência por parceiro íntimo

ABSTRACT This study aims to evaluate the practice of breastfeeding among women in intimate partner violence situation during the current pregnancy for the duration of exclusive breastfeeding, the level of self-efficacy in breastfeeding, related factors from the beginning, the establishment of breastfeeding and early weaning. Cross-sectional study. 63 women in intimate partner violence situation in the current pregnancy participated, identified by survey in antenatal service. Data collection was performed in the prenatal and postpartum period. We used a questionnaire to identify the intimate partner violence, the Breastfeeding Self-Efficacy Scale and medical record information. The average days of exclusive breastfeeding was 19.08. There was no statistically significant association between the duration of exclusive breastfeeding at 30 and 70 days postpartum and intimate partner violence and care practices with level of self-efficacy to breastfeed. We found association between the type of breastfeeding at 30 and 70 days postpartum and better conditions vital of newborns with level of self-efficacy to breastfeed.

RESUMEN Este estúdio tiene como evaluar la práctica de la lactancia materna entre mujeres em situación de violência del compañero íntimo durante elembarazo actual para la duración de lan lactancia materna exclusiva, el nivel de autoeficacia de amamantar y factores relacionados a la iniciación, el establecimiento de la lactancia y el destete precoz. Estudio transversal. 63 mujeres participaron em situación de violência del compañero íntimo em el embarazo actual, identificado por encuesta em el servicio prenatal. La recolección de datos se realizo em el prenatal y postparto. Se utilizo um cuestionario de identificación de violência del compañero íntimo, Breastfeeding Self-Efficacy Scale y información de los registros médicos. El promedio de días de lactancia materna exclusiva fue 19,08. No hubo asociacióne stadísticamente significativa entre la duración de la lactancia materna exclusiva a los 30 y 70 días después del parto y tipos de violência del compañero, asi como prácticas de cuidado con nível de autoeficacia de amamentar. Se encontro asociación entre el tipo de lactancia materna a los 30 y 70 días después del parto y mejores condiciones vitales de lo recien nacido con el nível de autoeficacia de amamentar.

RESUMO Este estudo busca analisar a prática da amamentação entre mulheres em situação de violência por parceiro íntimo durante a gestação atual quanto à duração do aleitamento materno exclusivo, o nível de autoeficácia para amamentar e fatores relacionados ao início, estabelecimento da amamentação e desmame precoce. Trata-se de um estudo transversal. Participaram 63 mulheres em situação de violência por parceiro íntimo na gestação atual, identificadas por inquérito em serviço pré-natal. A coleta de dados foi realizada no pré-natal e pós-parto. Utilizou-se questionário de identificação da violência por parceiro íntimo, a Breastfeeding Self-Efficacy Scale e informações dos prontuários. A média em dias de aleitamento materno exclusivo foi de 19,08. Não houve associação estatisticamente significativa entre a duração do aleitamento materno exclusivo com 30 e 70 dias pós-parto e tipos de violência por parceiro íntimo, bem como práticas assistenciais com nível de autoeficácia para amamentar. Verificamos associação entre o tipo de aleitamento materno com 30 e 70 dias pós-parto e melhores condições vitais do recém-nascido com nível de autoeficácia para amamentar.

Modeling strategic use of human computer interfaces with novel hidden Markov models.

Immersive software tools are virtual environments designed to give their users an augmented view of real-world data and ways of manipulating that data. As virtual environments, every action users make while interacting with these tools can be carefully logged, as can the state of the software and the information it presents to the user, giving these actions context. This data provides a high-resolution lens through which dynamic cognitive and behavioral processes can be viewed. In this report, we describe new methods for the analysis and interpretation of such data, utilizing a novel implementation of the Beta Process Hidden Markov Model (BP-HMM) for analysis of software activity logs. We further report the results of a preliminary study designed to establish the validity of our modeling approach. A group of 20 participants were asked to play a simple computer game, instrumented to log every interaction with the interface. Participants had no previous experience with the game's functionality or rules, so the activity logs collected during their naïve interactions capture patterns of exploratory behavior and skill acquisition as they attempted to learn the rules of the game. Pre- and post-task questionnaires probed for self-reported styles of problem solving, as well as task engagement, difficulty, and workload. We jointly modeled the activity log sequences collected from all participants using the BP-HMM approach, identifying a global library of activity patterns representative of the collective behavior of all the participants. Analyses show systematic relationships between both pre- and post-task questionnaires, self-reported approaches to analytic problem solving, and metrics extracted from the BP-HMM decomposition. Overall, we find that this novel approach to decomposing unstructured behavioral data within software environments provides a sensible means for understanding how users learn to integrate software functionality for strategic task pursuit.

An electroencephalographic recording platform for real-time seizure detection.

There are currently no clinical devices that can be worn by epilepsy patients who suffer from intractable seizures to warn them of seizure onset. Here we summarize state-of-the-art therapies and devices, and present a second-generation hardware platform in which seizure detection algorithms may be programmed into the device. Bi-polar electrographic data is presented for a prototype device and future implementations are discussed.