Plasma Magnetohydrodynamics and Energy Conversion

Contains reports on three research projects.National Science Foundation under Grant G-9330U. S. Air Force (Aeronautical Systems Division) under Contract AF33(616)-7624 with the Aeronautical Accessories Laboratory, Wright-Patterson Air Force Base, Ohi

The Arp2/3 complex, UNC-115/abLIM, and UNC-34/Enabled regulate axon guidance and growth cone filopodia formation in Caenorhabditis elegans

<p>Abstract</p> <p>Background</p> <p>While many molecules involved in axon guidance have been identified, the cellular and molecular mechanisms by which these molecules regulate growth cone morphology during axon outgrowth remain to be elucidated. The actin cytoskeleton of the growth cone underlies the formation of lamellipodia and filopodia that control growth cone outgrowth and guidance. The role of the Arp2/3 complex in growth cone filopodia formation has been controversial, and other mechanisms of growth cone filopodia formation remain to be described.</p> <p>Results</p> <p>Here we show that mutations in genes encoding the Arp2/3 complex (<it>arx </it>genes) caused defects in axon guidance. Analysis of developing growth cones <it>in vivo </it>showed that <it>arx </it>mutants displayed defects in filopodia and reduced growth cone size. Time-lapse analysis of growth cones in living animals indicated that <it>arx </it>mutants affected the rate of growth cone filopodia formation but not filopodia stability or length. Two other actin modulatory proteins, UNC-115/abLIM and UNC-34/Enabled, that had been shown previously to affect axon guidance had overlapping roles with Arp2/3 in axon guidance and also affected the rate of filopodia initiation but not stability or length.</p> <p>Conclusion</p> <p>Our results indicate that the Arp2/3 complex is required cell-autonomously for axon guidance and growth cone filopodia initiation. Furthermore, they show that two other actin-binding proteins, UNC-115/abLIM and UNC-34/Enabled, also control growth cone filopodia formation, possibly in parallel to Arp2/3. These studies indicate that, <it>in vivo</it>, multiple actin modulatory pathways including the Arp2/3 complex contribute to growth cone filopodia formation during growth cone outgrowth.</p

PEOPLES: A Tool to Measure Community Resilience

This paper provides a novel method to quantitatively assess the resilience of communities at various scales. The proposed method is based on the PEOPLES framework and it takes an indicator-based approach as an engine for its algorithm. PEOPLES is a framework for identifying the different resilience aspects of a community and for providing new ways through which the decision makers can take actions. The framework comprises seven dimensions, each of which is the collection of more specific components and indicators. Each indicator is accompanied with a measure allowing the analytical computation of the indicator’s performance. The measures are presented in the form of continuous functions whose parameters can be analytically obtained. The output of the methodology is a performance function for each indicator and a resilience index for the whole community. A case study illustrating the application of the methodology is also provided in the paper

Psychometric Properties of the Altarum Consumer Engagement (ACE) Measure of Activation in Patients with Prediabetes.

BackgroundPatient activation is associated with better outcomes in chronic conditions.ObjectiveWe evaluated the psychometric properties of the 12-item Altarum Consumer Engagement™ Measure (ACE-12) in patients with prediabetes.ParticipantsACE-12 was administered to patients in the Prediabetes Informed Decisions and Education Study.Main measuresWe conducted an exploratory factor analysis followed by confirmatory factor analytic models. We evaluated item response categories using item characteristic curves. Construct validity was assessed by examining correlations of the ACE-12 scales with education, depressive symptoms, self-rated health, hemoglobin A1c, body mass index, and weight loss.Key resultsParticipants (n = 515) had a median age of 58; 56% were female; 17% Hispanic; 54% were non-White. The scree plot and Tucker and Lewis reliability coefficient (0.95) suggested three factors similar to the original scales. One item loaded on the navigation rather than the informed choice scale. Ordinal alpha coefficients for the original scales were commitment (0.75); informed choice (0.71); and navigation (0.54). ICCs indicated that one or more of the response categories for 5 of the 12 items were never most likely to be selected. Patients with lower education were less activated on the commitment (r = - 0.124, p = 0.004), choice (r = - 0.085, p = 0.009), and overall score (r = - 0.042, p = 0.011). Patients with depressive symptoms had lower commitment (r = - 0.313, p ≤ 0.001) and overall scores (r = - 0.172, p = 0.012). Patients with poorer health scored lower on the Commitment (r = - 0.308, p ≤ 0.001), Navigation (r = - 0.137, p ≤ 0.001), and overall score (r = - 0.279, p ≤ 0.001).ConclusionThe analyses provide some support for the psychometric properties of the ACE-12 in prediabetic patients. Future research evaluating this tool among patients with other chronic conditions are needed to determine whether Q1 (I spend a lot of time learning about health) should remain in the informed choice or be included in the navigation scale. Additional items may be needed to yield acceptable reliability for the navigation scale

Occipital alpha activity during stimulus processing gates the information flow to object-selective cortex.

Given the limited processing capabilities of the sensory system, it is essential that attended information is gated to downstream areas, whereas unattended information is blocked. While it has been proposed that alpha band (8–13 Hz) activity serves to route information to downstream regions by inhibiting neuronal processing in task-irrelevant regions, this hypothesis remains untested. Here we investigate how neuronal oscillations detected by electroencephalography in visual areas during working memory encoding serve to gate information reflected in the simultaneously recorded blood-oxygenation-level-dependent (BOLD) signals recorded by functional magnetic resonance imaging in downstream ventral regions. We used a paradigm in which 16 participants were presented with faces and landscapes in the right and left hemifields; one hemifield was attended and the other unattended. We observed that decreased alpha power contralateral to the attended object predicted the BOLD signal representing the attended object in ventral object-selective regions. Furthermore, increased alpha power ipsilateral to the attended object predicted a decrease in the BOLD signal representing the unattended object. We also found that the BOLD signal in the dorsal attention network inversely correlated with visual alpha power. This is the first demonstration, to our knowledge, that oscillations in the alpha band are implicated in the gating of information from the visual cortex to the ventral stream, as reflected in the representationally specific BOLD signal. This link of sensory alpha to downstream activity provides a neurophysiological substrate for the mechanism of selective attention during stimulus processing, which not only boosts the attended information but also suppresses distraction. Although previous studies have shown a relation between the BOLD signal from the dorsal attention network and the alpha band at rest, we demonstrate such a relation during a visuospatial task, indicating that the dorsal attention network exercises top-down control of visual alpha activity

Southern Massive Stars at High Angular Resolution: Observational Campaign and Companion Detection

Multiplicity is one of the most fundamental observable properties of massive O-type stars and offers a promising way to discriminate between massive star formation theories. Nevertheless, companions at separations between 1 and 100 mas remain mostly unknown due to intrinsic observational limitations. [...] The Southern MAssive Stars at High angular resolution survey (SMASH+) was designed to fill this gap by providing the first systematic interferometric survey of Galactic massive stars. We observed 117 O-type stars with VLTI/PIONIER and 162 O-type stars with NACO/SAM, respectively probing the separation ranges 1-45 and 30-250mas and brightness contrasts of Delta H < 4 and Delta H < 5. Taking advantage of NACO's field-of-view, we further uniformly searched for visual companions in an 8''-radius down to Delta H = 8. This paper describes the observations and data analysis, reports the discovery of almost 200 new companions in the separation range from 1mas to 8'' and presents the catalog of detections, including the first resolved measurements of over a dozen known long-period spectroscopic binaries. Excluding known runaway stars for which no companions are detected, 96 objects in our main sample (DEC < 0 deg; H<7.5) were observed both with PIONIER and NACO/SAM. The fraction of these stars with at least one resolved companion within 200mas is 0.53. Accounting for known but unresolved spectroscopic or eclipsing companions, the multiplicity fraction at separation < 8'' increases to f_m = 0.91 +/- 0.03. The fraction of luminosity class V stars that have a bound companion reaches 100% at 30mas while their average number of physically connected companions within 8'' is f_c = 2.2 +/- 0.3. This demonstrates that massive stars form nearly exclusively in multiple systems. Additionally, the nine non-thermal (NT) radio emitters observed by SMASH+ are all resolved [...]Comment: 57 pages, 20 figures, 7 tables; accepted for publication in ApJ

Adaptive correction of depth-induced aberrations in multiphoton scanning microscopy using a deformable mirror

We demonstrate adaptive aberration correction for depth-induced spherical aberration in a multiphoton scanning microscope with a micromachined deformable mirror. Correction was made using a genetic learning algorithm with two-photon fluorescence intensity feedback to determine the desired shape for an adaptive mirror. For a 40×/0.6 NA long working distance objective, the axial scanning range was increased from 150 mm to 600 mm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72425/1/j.1365-2818.2002.01004.x.pd

Radio Galaxy Zoo: Knowledge Transfer Using Rotationally Invariant Self-Organising Maps

With the advent of large scale surveys the manual analysis and classification of individual radio source morphologies is rendered impossible as existing approaches do not scale. The analysis of complex morphological features in the spatial domain is a particularly important task. Here we discuss the challenges of transferring crowdsourced labels obtained from the Radio Galaxy Zoo project and introduce a proper transfer mechanism via quantile random forest regression. By using parallelized rotation and flipping invariant Kohonen-maps, image cubes of Radio Galaxy Zoo selected galaxies formed from the FIRST radio continuum and WISE infrared all sky surveys are first projected down to a two-dimensional embedding in an unsupervised way. This embedding can be seen as a discretised space of shapes with the coordinates reflecting morphological features as expressed by the automatically derived prototypes. We find that these prototypes have reconstructed physically meaningful processes across two channel images at radio and infrared wavelengths in an unsupervised manner. In the second step, images are compared with those prototypes to create a heat-map, which is the morphological fingerprint of each object and the basis for transferring the user generated labels. These heat-maps have reduced the feature space by a factor of 248 and are able to be used as the basis for subsequent ML methods. Using an ensemble of decision trees we achieve upwards of 85.7% and 80.7% accuracy when predicting the number of components and peaks in an image, respectively, using these heat-maps. We also question the currently used discrete classification schema and introduce a continuous scale that better reflects the uncertainty in transition between two classes, caused by sensitivity and resolution limits