Collective Correlations of Brodmann Areas fMRI Study with RMT-Denoising

We study collective behavior of Brodmann regions of human cerebral cortex using functional Magnetic Resonance Imaging (fMRI) and Random Matrix Theory (RMT). The raw fMRI data is mapped onto the cortex regions corresponding to the Brodmann areas with the aid of the Talairach coordinates. Principal Component Analysis (PCA) of the Pearson correlation matrix for 41 different Brodmann regions is carried out to determine their collective activity in the idle state and in the active state stimulated by tapping. The collective brain activity is identified through the statistical analysis of the eigenvectors to the largest eigenvalues of the Pearson correlation matrix. The leading eigenvectors have a large participation ratio. This indicates that several Broadmann regions collectively give rise to the brain activity associated with these eigenvectors. We apply random matrix theory to interpret the underlying multivariate data

Systematic Review: Occupational Therapy & Improving Social Participation for At-Risk Youth in School

Objectives of Presentation: 1. Describe occupational therapists’ role in working with at-risk youth. 2. Identify 1-2 effective interventions for increasing social participation amongst at-risk youth. 3. Discuss how the current evidence regarding interventions within the scope of occupational therapy for at-risk youth can be best integrated into practice. PICO: What school-based interventions within the scope of occupational therapy practice aid in improving social participation for at-risk youth? Methods: Creation of clinical question, list of search terms for literature search Systematic search of databases: CINAHL, PubMed, Cochrane, & Scopus List of inclusion/exclusion criteria created Presentation: 50 minute

A molecular phylogenetic analysis of the genera of fruit doves and allies using dense taxonomic sampling

Fruit doves and their allies are a diverse group within the pigeon and dove family (Aves: Columbidae). Progress towards subfamilial classification of Columbidae relies on identifying major groups and the phylogenetic relationships within these groups. One such recently proposed group is the Raphinae based on previous evidence that the extinct dodo is potentially within what was formerly recognized as the Treroninae (fruit doves and allies). Although several studies have explored the phylogenetic relationships within Columbidae, most have focused either on broad-scale, familial level relationships or finer scale, species level relationships. Here we use mitochondrial and nuclear gene sequences from a diverse taxonomic sample to identify relationships among the genera and species of fruit doves and their allies. In particular our goal is to identify which of these genera should be included within Raphinae (the name which has taxonomic priority over Treroninae), focusing on an inclusive, well-supported monophyletic group. We also use dense taxon sampling to explore relationships among genera and species in this group, expanding on previous studies. In addition, we use resulting phylogenetic hypotheses to reconstruct the ancestral evolutionary history of foraging mode and biogeographic patterns of dispersal within the group. We used two data sets for our phylogenetic analysis: the first consisting of novel sequences generated for this project and the second with additional, previously published sequences from the fruit dove genus (Ptilinopus). Our analyses found support for the monophyly of a clade that contains a large fraction of the genera currently classified within Raphinae and also found several well-supported clades within this group of pigeons and doves. Character reconstruction methods based on the resulting phylogeny recover multiple transitions from a terrestrial to an arboreal foraging mode and evidence for multiple dispersal events from Asia to Africa throughout the history of the clade.is peer reviewedOpe

Fluorescence Imaging Study of Transition in Underexpanded Free Jets

Planar laser-induced fluorescence (PLIF) is demonstrated to be a valuable tool for studying the onset of transition to turbulence. For this study, we have used PLIF of nitric oxide (NO) to image underexpanded axisymmetric free jets issuing into a low-pressure chamber through a smooth converging nozzle with a sonic orifice. Flows were studied over a range of Reynolds numbers and nozzle-exit-to-ambient pressure ratios with the aim of empirically determining criteria governing the onset of turbulence. We have developed an image processing technique, involving calculation of the standard deviation of the intensity in PLIF images, in order to aid in the identification of turbulence. We have used the resulting images to identify laminar, transitional and turbulent flow regimes. Jet scaling parameters were used to define a rescaled Reynolds number that incorporates the influence of a varying pressure ratio. An empirical correlation was found between transition length and this rescaled Reynolds number for highly underexpanded jets

The Effect of Impingement on Transitional Behavior in Underexpanded Jets

An investigation into the development of flow unsteadiness in impinging axisymmetric underexpanded jets has been conducted at NASA Langley Research Center. The study has examined the effect of an impingement target placed at various distances and angles on transitional behavior of such jets. Two nozzles, with exit Mach numbers of 1.0 and 2.6, were used in this investigation. Planar laser-induced fluorescence of nitric oxide (NO PLIF) has been used to identify flow unsteadiness and to image transitional and turbulent flow features. Measurements of the location of the onset of various degrees of unsteady flow behavior have been made using these PLIF images. Both qualitative and quantitative comparisons are presented to demonstrate the observed effects of impingement and flow parameters on the process of the transition to turbulence. The presence of the impingement target was found to significantly shorten the distance to transition to turbulence by up to a factor of approximately three, with closer targets resulting in slightly shorter distance to transition and turbulence. The location at which the flow first exhibits unsteadiness was found to have a strong dependence on the presence and location of key flow structures. This paper presents quantitative results on transition criteria for free and impinging jets

Identification of Instability Modes of Transition in Underexpanded Jets

A series of experiments into the behavior of underexpanded jet flows has been conducted at NASA Langley Research Center. Two nozzles supplied with high-pressure gas were used to generate axisymmetric underexpanded jets exhausting into a low-pressure chamber. These nozzles had exit Mach numbers of 1 and 2.6, though this paper will present cases involving only the supersonic nozzle. Reynolds numbers based on nozzle exit conditions ranged from about 300 to 22,000, and nozzle exit-to-ambient jet pressure ratios ranged from about 1 to 25. For the majority of cases, the jet fluid was a mixture of 99.5% nitrogen seeded with 0.5% nitric oxide (NO). Planar laser-induced fluorescence (PLIF) of NO is used to visualize the flow, visualizing planar slices of the flow rather than path integrated measurements. In addition to revealing the size and location of flow structures, PLIF images were also used to identify unsteady jet behavior in order to quantify the conditions governing the transition to turbulent flow. Flow structures that contribute to the growth of flow instabilities have been identified, and relationships between Reynolds number and transition location are presented. By highlighting deviations from mean flow properties, PLIF images are shown to aide in the identification and characterization of flow instabilities and the resulting process of transition to turbulence

Fluorescence Imaging Study of Impinging Underexpanded Jets

An experiment was designed to create a simplified simulation of the flow through a hole in the surface of a hypersonic aerospace vehicle and the subsequent impingement of the flow on internal structures. In addition to planar laser-induced fluorescence (PLIF) flow visualization, pressure measurements were recorded on the surface of an impingement target. The PLIF images themselves provide quantitative spatial information about structure of the impinging jets. The images also help in the interpretation of impingement surface pressure profiles by highlighting the flow structures corresponding to distinctive features of these pressure profiles. The shape of the pressure distribution along the impingement surface was found to be double-peaked in cases with a sufficiently high jet-exit-to-ambient pressure ratio so as to have a Mach disk, as well as in cases where a flow feature called a recirculation bubble formed at the impingement surface. The formation of a recirculation bubble was in turn found to depend very sensitively upon the jet-exit-to-ambient pressure ratio. The pressure measured at the surface was typically less than half the nozzle plenum pressure at low jet pressure ratios and decreased with increasing jet pressure ratios. Angled impingement cases showed that impingement at a 60deg angle resulted in up to a factor of three increase in maximum pressure at the plate compared to normal incidence