311 research outputs found

    The complexity of the California recall election

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    The October 7, 2003 California Recall Election strained California’s direct democracy. In recent California politics there has not been a statewide election conducted on such short notice; county election officials were informed on July 24 that the election would be held on October 7. Nor has California recently seen a ballot with so many candidates running for a single statewide office (see Mueller 1970). Under easy ballot access requirements, Secretary of State Kevin Shelley certified 135 candidates for the official ballot on August 13^1. In the recall, voters cast votes on (1) whether to recall Governor Davis from office, and (2) his possible successor. These two voting decisions were made independent by the federal district court’s decision on July 29. The court’s decision invalidated a state law requiring a vote on the recall question in order for a vote on the successor election to be counted (Partnoy et al. 2003). The abbreviated election calendar also led to many improvisations, including a dramatically reduced number of precinct poll sites throughout the state and the unprecedented ability of military personnel, their dependents, and civilians living overseas to return their absentee ballots by fax. These problems produced litigation and speculation that substantial problems would mar the election and throw the outcome of both the recall and a possible successor’s election into doubt. In the end, the litigation failed to stall the recall election, and the large final vote margins on both the recall question and the successor ballot seemingly overwhelmed Election Day problems. In this paper, we concentrate on some of the problems produced by the complexity of the recall election, but we do not attempt an exhaustive presentation of these problems. We focus on polling place problems on election day, the problems associated with translating the complicated recall election ballot into six languages, how the long ballot influenced voter behavior, and voter difficulties with the ballot measured with survey data. We conclude with a short discussion of the possible impact of these problems on the recall election

    Semi-Automatic segmentation of multiple mouse embryos in MR images

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    <p>Abstract</p> <p>Background</p> <p>The motivation behind this paper is to aid the automatic phenotyping of mouse embryos, wherein multiple embryos embedded within a single tube were scanned using Magnetic Resonance Imaging (MRI).</p> <p>Results</p> <p>Our algorithm, a modified version of the simplex deformable model of Delingette, addresses various issues with deformable models including initialization and inability to adapt to boundary concavities. In addition, it proposes a novel technique for automatic collision detection of multiple objects which are being segmented simultaneously, hence avoiding major leaks into adjacent neighbouring structures. We address the initialization problem by introducing balloon forces which expand the initial spherical models close to the true boundaries of the embryos. This results in models which are less sensitive to initial minimum of two fold after each stage of deformation. To determine collision during segmentation, our unique collision detection algorithm finds the intersection between binary masks created from the deformed models after every few iterations of the deformation and modifies the segmentation parameters accordingly hence avoiding collision.</p> <p>We have segmented six tubes of three dimensional MR images of multiple mouse embryos using our modified deformable model algorithm. We have then validated the results of the our semi-automatic segmentation versus manual segmentation of the same embryos. Our Validation shows that except paws and tails we have been able to segment the mouse embryos with minor error.</p> <p>Conclusions</p> <p>This paper describes our novel multiple object segmentation technique with collision detection using a modified deformable model algorithm. Further, it presents the results of segmenting magnetic resonance images of up to 32 mouse embryos stacked in one gel filled test tube and creating 32 individual masks.</p

    The Effects of Square-Stepping Exercise on Risk of Falling and Balance in Senior Adults

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    As people age, their body systems gradually deteriorate. Muscle function and the vestibular system slowly deteriorate leading to lower body instability. Older adults who struggle with dizziness and imbalance are more prone to falling. Dizziness and imbalance cause falls, and falls are the leading cause of hospitalization and accidental death in older adults (Shinichi & Tatsuya, 2015). It is possible to prevent and reduce the risk of falls through balance training. It is crucial that older adults take the steps needed to improve their balance and therefore reduce their risk of falling. PURPOSE: To evaluate the effect of a 10-week Square-Stepping Exercise (SSE) program in older adults using the Biodex balance system. METHODS: Eleven adults over the age of 60 and involved in the Senior Jacket program at Cedarville University participated in this 10-week study (0 males, 11 females; mean age=76). Measurements taken prior to and after the intervention include Activities-specific Balance Confidence (ABC) Scale, Timed-Up-And-Go Test, 30-Second Chair Stand Test, Limits of Stability Test, and Fall Risk Test. A Repeated Measures ANOVA was used to determine changes in initial and final balance testing scores. RESULTS: The study revealed that significant differences were found for the functional fitness tests. SPSS indicated a significant difference in improvement from pretest to posttest for the Timed-Up-and-Go Test (P = .003) as well as the 30-Second Chair Stand Test (P = .043). For the Limits of Stability test, there was no significant change from pretest to posttest for the overall (P =0.162) or any of the 8 directions. The Fall Risk Test score also showed no significant change (P =0.831). The ABC Scale test did not show significant improvement either (P = 0.995). CONCLUSION: Overall, the results showed that the participants significantly benefited from the training program in areas of functional fitness. Unfortunately, there was no significant improvement with the Biodex balance system’s Fall Risk Test or Limits of Stability Test. Results may be due to the participants already having good balance as they were well below the normative data for risk of falling. It could also be because the training was not specific enough for improvements in the Fall Risk and Limits of Stability tests

    Casimir Energies for 6D Supergravities Compactified on T_2/Z_N with Wilson Lines

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    We compute (as functions of the shape and Wilson-line moduli) the one-loop Casimir energy induced by higher-dimensional supergravities compactified from 6D to 4D on 2-tori, and on some of their Z_N orbifolds. Detailed calculations are given for a 6D scalar field having an arbitrary 6D mass m, and we show how to extend these results to higher-spin fields for supersymmetric 6D theories. Particular attention is paid to regularization issues and to the identification of the divergences of the potential, as well as the dependence of the result on m, including limits for which m^2 A> 1 where A is the volume of the internal 2 dimensions. Our calculation extends those in the literature to very general boundary conditions for fields about the various cycles of these geometries. The results have potential applications towards Supersymmetric Large Extra Dimensions (SLED) as a theory of the Dark Energy. First, they provide an explicit calculation within which to follow the dependence of the result on the mass of the bulk states which travel within the loop, and for heavy masses these results bear out the more general analysis of the UV-sensitivity obtained using heat-kernel methods. Second, because the potentials we find describe the dynamics of the classical flat directions of these compactifications, within SLED they would describe the present-day dynamics of the Dark Energy.Comment: 40 pages, 7 figure

    Realistic Adversarial Data Augmentation for MR Image Segmentation

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    Neural network-based approaches can achieve high accuracy in various medical image segmentation tasks. However, they generally require large labelled datasets for supervised learning. Acquiring and manually labelling a large medical dataset is expensive and sometimes impractical due to data sharing and privacy issues. In this work, we propose an adversarial data augmentation method for training neural networks for medical image segmentation. Instead of generating pixel-wise adversarial attacks, our model generates plausible and realistic signal corruptions, which models the intensity inhomogeneities caused by a common type of artefacts in MR imaging: bias field. The proposed method does not rely on generative networks, and can be used as a plug-in module for general segmentation networks in both supervised and semi-supervised learning. Using cardiac MR imaging we show that such an approach can improve the generalization ability and robustness of models as well as provide significant improvements in low-data scenarios

    White matter injury predicts disrupted functional connectivity and microstructure in very preterm born neonates

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    © 2018 The Authors Objective: To determine whether the spatial extent and location of early-identified punctate white matter injury (WMI) is associated with regionally-specific disruptions in thalamocortical-connectivity in very-preterm born neonates. Methods: 37 very-preterm born neonates (median gestational age: 28.1 weeks; interquartile range [IQR]: 27–30) underwent early MRI (median age 32.9 weeks; IQR: 32–35), and WMI was identified in 13 (35%) neonates. Structural T1-weighted, resting-state functional Magnetic Resonance Imaging (rs-fMRI, n = 34) and Diffusion Tensor Imaging (DTI, n = 31) sequences were acquired using 3 T-MRI. A probabilistic map of WMI was developed for the 13 neonates demonstrating brain injury. A neonatal atlas was applied to the WMI maps, rs-fMRI and DTI analyses to extract volumetric, functional and microstructural data from regionally-specific brain areas. Associations of thalamocortical-network strength and alterations in fractional anisotropy (FA, a measure of white-matter microstructure) with WMI volume were assessed in general linear models, adjusting for age at scan and cerebral volumes. Results: WMI volume in the superior (β = −0.007; p =.02) and posterior corona radiata (β = −0.01; p =.01), posterior thalamic radiations (β = −0.01; p =.005) and superior longitudinal fasciculus (β = −0.02; p =.001) was associated with reduced connectivity strength between thalamus and parietal resting-state networks. WMI volume in the left (β = −0.02; p =.02) and right superior corona radiata (β = −0.03; p =.008), left posterior corona radiata (β = −0.03; p =.01), corpus callosum (β = −0.11; p \u3c.0001) and right superior longitudinal fasciculus (β = −0.02; p =.02) was associated with functional connectivity strength between thalamic and sensorimotor networks. Increased WMI volume was also associated with decreased FA values in the corpus callosum (β = −0.004, p =.015). Conclusions: Regionally-specific alterations in early functional and structural network complexity resulting from WMI may underlie impaired outcomes

    MSLED, Neutrino Oscillations and the Cosmological Constant

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    We explore the implications for neutrino masses and mixings within the minimal version of the supersymmetric large-extra-dimensions scenario (MSLED). This model was proposed in {\tt hep-ph/0404135} to extract the phenomenological implications of the promising recent attempt (in {\tt hep-th/0304256}) to address the cosmological constant problem. Remarkably, we find that the simplest couplings between brane and bulk fermions within this approach can lead to a phenomenologically-viable pattern of neutrino masses and mixings that is also consistent with the supernova bounds which are usually the bane of extra-dimensional neutrino models. Under certain circumstances the MSLED scenario can lead to a lepton mixing (PMNS) matrix close to the so-called bi-maximal or the tri-bimaximal forms (which are known to provide a good description of the neutrino oscillation data). We discuss the implications of MSLED models for neutrino phenomenology.Comment: 38 pages, 1 figure; Reposted with a few additional reference

    Altered Neurocircuitry in the Dopamine Transporter Knockout Mouse Brain

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    The plasma membrane transporters for the monoamine neurotransmitters dopamine, serotonin, and norepinephrine modulate the dynamics of these monoamine neurotransmitters. Thus, activity of these transporters has significant consequences for monoamine activity throughout the brain and for a number of neurological and psychiatric disorders. Gene knockout (KO) mice that reduce or eliminate expression of each of these monoamine transporters have provided a wealth of new information about the function of these proteins at molecular, physiological and behavioral levels. In the present work we use the unique properties of magnetic resonance imaging (MRI) to probe the effects of altered dopaminergic dynamics on meso-scale neuronal circuitry and overall brain morphology, since changes at these levels of organization might help to account for some of the extensive pharmacological and behavioral differences observed in dopamine transporter (DAT) KO mice. Despite the smaller size of these animals, voxel-wise statistical comparison of high resolution structural MR images indicated little morphological change as a consequence of DAT KO. Likewise, proton magnetic resonance spectra recorded in the striatum indicated no significant changes in detectable metabolite concentrations between DAT KO and wild-type (WT) mice. In contrast, alterations in the circuitry from the prefrontal cortex to the mesocortical limbic system, an important brain component intimately tied to function of mesolimbic/mesocortical dopamine reward pathways, were revealed by manganese-enhanced MRI (MEMRI). Analysis of co-registered MEMRI images taken over the 26 hours after introduction of Mn^(2+) into the prefrontal cortex indicated that DAT KO mice have a truncated Mn^(2+) distribution within this circuitry with little accumulation beyond the thalamus or contralateral to the injection site. By contrast, WT littermates exhibit Mn^(2+) transport into more posterior midbrain nuclei and contralateral mesolimbic structures at 26 hr post-injection. Thus, DAT KO mice appear, at this level of anatomic resolution, to have preserved cortico-striatal-thalamic connectivity but diminished robustness of reward-modulating circuitry distal to the thalamus. This is in contradistinction to the state of this circuitry in serotonin transporter KO mice where we observed more robust connectivity in more posterior brain regions using methods identical to those employed here

    Does having a twin-brother make for a bigger brain?

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    Objective: Brain volume of boys is larger than that of girls by ∼10%. Prenatal exposure to testosterone has been suggested in the masculinization of the brain. For example, in litter-bearing mammals intrauterine position increases prenatal testosterone exposure through adjacent male fetuses, resulting in masculinization of brain morphology. Design: The influence of intrauterine presence of a male co-twin on masculinization of human brain volume was studied in 9-year old twins. Methods: Magnetic resonance imaging brain scans, current testosterone, and estradiol levels were acquired from four groups of dizygotic (DZ) twins: boys from same-sex twin-pairs (SSM), boys from opposite-sex twin-pairs (OSM), girls from opposite-sex twin-pairs (OSF), and girls from same-sex twin-pairs (SSF; n=119 individuals). Data on total brain, cerebellum, gray and white matter volumes were examined. Results: Irrespective of their own sex, children with a male co-twin as compared to children with a female co-twin had larger total brain (+2.5%) and cerebellum (+5.5%) volumes. SSM, purportedly exposed to the highest prenatal testosterone levels, were found to have the largest volumes, followed by OSM, OSF and SSF children. Birth weight partly explained the effect on brain volumes. Current testosterone and estradiol levels did not account for the volumetric brain differences. However, the effects observed in children did not replicate in adult twins. Conclusions: Our study indicates that sharing the uterus with a DZ twin brother increases total brain volume in 9-year olds. The effect may be transient and limited to a critical period in childhood. © 2009 European Society of Endocrinology
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