WorldWideScience

Sample records for voxel size matters

  1. Optimal voxel size for measuring global gray and white matter proton metabolite concentrations using chemical shift imaging

    DEFF Research Database (Denmark)

    Hanson, Lars Peter Grüner; Adalsteinsson, E; Pfefferbaum, A

    2000-01-01

    Quantification of gray and white matter levels of spectroscopically visible metabolites can provide important insights into brain development and pathological conditions. Chemical shift imaging offers a gain in efficiency for estimation of global gray and white matter metabolite concentrations...

  2. Schizophrenia Patients Demonstrate Both Inter-Voxel Level and Intra-Voxel Level White Matter Alterations.

    Science.gov (United States)

    Zhuo, Chuanjun; Ma, Xiaolei; Qu, Hongru; Wang, Lina; Jia, Feng; Wang, Chunli

    2016-01-01

    Fractional anisotropy (FA) and mean diffusivity (MD) are the most frequently used metrics to investigate white matter impairments in mental disorders. However, these two metrics are derived from intra-voxel analyses and only reflect the diffusion properties solely within the voxel unit. Local diffusion homogeneity (LDH) is a newly developed inter-voxel metric which quantifies the local coherence of water molecule diffusion in a model-free manner. In this study, 94 schizophrenia patients and 91 sex- and age-matched healthy controls underwent diffusion tensor imaging (DTI) examinations. White matter integrity was assessed by FA, MD and LDH. Group differences in these metrics were compared using tract-based spatial statistics (TBSS). Compared with healthy controls, schizophrenia patients exhibited reduced FA and increased MD in the corpus callosum, cingulum, internal capsule, fornix and widespread superficial white matter in the frontal, parietal, occipital and temporal lobes. We also found decreased LDH in the corpus callosum, cingulum, internal capsule and fornix in schizophrenia. Our findings suggest that both intra-voxel and inter-voxel diffusion metrics are able to detect impairments in the anisotropic white matter regions, and intra-voxel diffusion metrics could detect additional impairments in the widespread isotropic white matter regions in schizophrenia.

  3. Influence of voxel size on specific absorbed fractions and S-values in a mouse voxel phantom.

    Science.gov (United States)

    Mohammadi, A; Kinase, S

    2011-02-01

    Photon and electron specific absorbed fractions (SAFs) and S-values have been evaluated using mouse voxel phantoms. In voxel phantoms, it is important to choose the voxel size carefully since it affects the accuracy of results. In this study, two mouse voxel phantoms were constructed, with cubic voxels, one with 0.1-mm sides and the other with 0.4-mm sides. The sources were considered to be distributed uniformly in the main organs and the radiation transport was simulated using the Monte Carlo code EGS4. It was found that the effect of voxel size on SAFs for self-irradiation was not high (voxel size was investigated on S-values for some beta emitters such as (131)I, (153)Sm, (188)Re and (90)Y.

  4. Size matter!

    DEFF Research Database (Denmark)

    Hansen, Pelle Guldborg; Jespersen, Andreas Maaløe; Skov, Laurits Rhoden

    2015-01-01

    Objectives We examined how a reduction in plate size would affect the amount of food waste from leftovers in a field experiment at a standing lunch for 220 CEOs. Methods A standing lunch for 220 CEOs in the Danish Opera House was arranged to feature two identical buffets with plates of two differ...

  5. Size matters

    Energy Technology Data Exchange (ETDEWEB)

    Forst, Michael

    2012-11-01

    The shakeout in the solar cell and module industry is in full swing. While the number of companies and production locations shutting down in the Western world is increasing, the capacity expansion in the Far East seems to be unbroken. Size in combination with a good sales network has become the key to success for surviving in the current storm. The trade war with China already looming on the horizon is adding to the uncertainties. (orig.)

  6. A voxel-based approach to gray matter asymmetries.

    Science.gov (United States)

    Luders, E; Gaser, C; Jancke, L; Schlaug, G

    2004-06-01

    Voxel-based morphometry (VBM) was used to analyze gray matter (GM) asymmetries in a large sample (n = 60) of male and female professional musicians with and without absolute pitch (AP). We chose to examine these particular groups because previous studies using traditional region-of-interest (ROI) analyses have shown differences in hemispheric asymmetry related to AP and gender. Voxel-based methods may have advantages over traditional ROI-based methods since the analysis can be performed across the whole brain with minimal user bias. After determining that the VBM method was sufficiently sensitive for the detection of differences in GM asymmetries between groups, we found that male AP musicians were more leftward lateralized in the anterior region of the planum temporale (PT) than male non-AP musicians. This confirmed the results of previous studies using ROI-based methods that showed an association between PT asymmetry and the AP phenotype. We further observed that male non-AP musicians revealed an increased leftward GM asymmetry in the postcentral gyrus compared to female non-AP musicians, again corroborating results of a previously published study using ROI-based methods. By analyzing hemispheric GM differences across our entire sample, we were able to partially confirm findings of previous studies using traditional morphometric techniques, as well as more recent, voxel-based analyses. In addition, we found some unusually pronounced GM asymmetries in our musician sample not previously detected in subjects unselected for musical training. Since we were able to validate gender- and AP-related brain asymmetries previously described using traditional ROI-based morphometric techniques, the results of our analyses support the use of VBM for examinations of GM asymmetries.

  7. Selection of voxel size and photon number in voxel-based Monte Carlo method: criteria and applications.

    Science.gov (United States)

    Li, Dong; Chen, Bin; Ran, Wei Yu; Wang, Guo Xiang; Wu, Wen Juan

    2015-01-01

    The voxel-based Monte Carlo method (VMC) is now a gold standard in the simulation of light propagation in turbid media. For complex tissue structures, however, the computational cost will be higher when small voxels are used to improve smoothness of tissue interface and a large number of photons are used to obtain accurate results. To reduce computational cost, criteria were proposed to determine the voxel size and photon number in 3-dimensional VMC simulations with acceptable accuracy and computation time. The selection of the voxel size can be expressed as a function of tissue geometry and optical properties. The photon number should be at least 5 times the total voxel number. These criteria are further applied in developing a photon ray splitting scheme of local grid refinement technique to reduce computational cost of a nonuniform tissue structure with significantly varying optical properties. In the proposed technique, a nonuniform refined grid system is used, where fine grids are used for the tissue with high absorption and complex geometry, and coarse grids are used for the other part. In this technique, the total photon number is selected based on the voxel size of the coarse grid. Furthermore, the photon-splitting scheme is developed to satisfy the statistical accuracy requirement for the dense grid area. Result shows that local grid refinement technique photon ray splitting scheme can accelerate the computation by 7.6 times (reduce time consumption from 17.5 to 2.3 h) in the simulation of laser light energy deposition in skin tissue that contains port wine stain lesions.

  8. Automatic Calibration Method of Voxel Size for Cone-beam 3D-CT Scanning System

    CERN Document Server

    Yang, Min; Liu, Yipeng; Men, Fanyong; Li, Xingdong; Liu, Wenli; Wei, Dongbo

    2013-01-01

    For cone-beam three-dimensional computed tomography (3D-CT) scanning system, voxel size is an important indicator to guarantee the accuracy of data analysis and feature measurement based on 3D-CT images. Meanwhile, the voxel size changes with the movement of the rotary table along X-ray direction. In order to realize the automatic calibration of the voxel size, a new easily-implemented method is proposed. According to this method, several projections of a spherical phantom are captured at different imaging positions and the corresponding voxel size values are calculated by non-linear least square fitting. Through these interpolation values, a linear equation is obtained, which reflects the relationship between the rotary table displacement distance from its nominal zero position and the voxel size. Finally, the linear equation is imported into the calibration module of the 3D-CT scanning system, and when the rotary table is moving along X-ray direction, the accurate value of the voxel size is dynamically expo...

  9. Effect of voxel size when calculating patient specific radionuclide dosimetry estimates using direct Monte Carlo simulation.

    Science.gov (United States)

    Hickson, Kevin J; O'Keefe, Graeme J

    2014-09-01

    The scalable XCAT voxelised phantom was used with the GATE Monte Carlo toolkit to investigate the effect of voxel size on dosimetry estimates of internally distributed radionuclide calculated using direct Monte Carlo simulation. A uniformly distributed Fluorine-18 source was simulated in the Kidneys of the XCAT phantom with the organ self dose (kidney ← kidney) and organ cross dose (liver ← kidney) being calculated for a number of organ and voxel sizes. Patient specific dose factors (DF) from a clinically acquired FDG PET/CT study have also been calculated for kidney self dose and liver ← kidney cross dose. Using the XCAT phantom it was found that significantly small voxel sizes are required to achieve accurate calculation of organ self dose. It has also been used to show that a voxel size of 2 mm or less is suitable for accurate calculations of organ cross dose. To compensate for insufficient voxel sampling a correction factor is proposed. This correction factor is applied to the patient specific dose factors calculated with the native voxel size of the PET/CT study.

  10. Whole-brain voxel-based morphometry of white matter in medial temporal lobe epilepsy

    Energy Technology Data Exchange (ETDEWEB)

    Yu Aihong [Department of Radiology, Xuanwu Hospital, Capital University of Medical Sciences, Beijing 100053 (China); Li Kuncheng [Department of Radiology, Xuanwu Hospital, Capital University of Medical Sciences, Beijing 100053 (China)], E-mail: Likuncheng@vip.sina.com; Li Lin; Shan Baoci [Institute of High Energy Physics, Chinese Academy of Sciences (China); Wang Yuping; Xue Sufang [Department of Neurology, Xuanwu Hospital, Capital University of Medical Sciences (China)

    2008-01-15

    Purpose: The purpose of this study was to analyze whole-brain white matter changes in medial temporal lobe epilepsy (MTLE). Materials and methods: We studied 23 patients with MTLE and 13 age- and sex-matched healthy control subjects using voxel-based morphometry (VBM) on T1-weighted 3D datasets. The seizure focus was right sided in 11 patients and left sided in 12. The data were collected on a 1.5 T MR system and analyzed by SPM 99 to generate white matter density maps. Results: Voxel-based morphometry revealed diffusively reduced white matter in MTLE prominently including bilateral frontal lobes, bilateral temporal lobes and corpus callosum. White matter reduction was also found in the bilateral cerebellar hemispheres in the left MTLE group. Conclusion: VBM is a simple and automated approach that is able to identify diffuse whole-brain white matter reduction in MTLE.

  11. Influence of voxel size settings in X-Ray CT Imagery of soil in scaling properties

    Science.gov (United States)

    Heck, R.; Scaiff, N. T.; Andina, D.; Tarquis, A. M.

    2012-04-01

    Fundamental to the interpretation and comparison of X-ray CT imagery of soil is recognition of the objectivity and consistency of procedures used to generate the 3D models. Notably, there has been a lack of consistency in the size of voxels used for diverse interpretations of soils features and processes; in part, this is due to the ongoing evolution of instrumentation and computerized image processing capacity. Moreover, there is still need for discussion on whether standard voxels sizes should be recommended, and what those would be. Regardless of any eventual adoption of such standards, there is a need to also consider the manner in which voxel size is set in the 3D imagery. In the typical approaches to X-ray CT imaging, voxel size may be set at three stages: image acquisition (involving the position of the sample relative to the tube and detector), image reconstruction (where binning of pixels in the acquired images may occur), as well as post-reconstruction re-sampling (which may involve algorithms such as tri-cubic convolution). This research evaluates and compares the spatial distribution of intra-aggregate voids in 3D imagery as well as their scaling properties, of equivalent voxel size, generated using various combinations of the afore-mentioned approaches. Funding provided by Spanish Ministerio de Ciencia e Innovación (MICINN) through project no. AGL2010-21501/AGR is greatly appreciated.

  12. Voxel-wise grey matter asymmetry analysis in left- and right-handers.

    Science.gov (United States)

    Ocklenburg, Sebastian; Friedrich, Patrick; Güntürkün, Onur; Genç, Erhan

    2016-10-28

    Handedness is thought to originate in the brain, but identifying its structural correlates in the cortex has yielded surprisingly incoherent results. One idea proclaimed by several authors is that structural grey matter asymmetries might underlie handedness. While some authors have found significant associations with handedness in different brain areas (e.g. in the central sulcus and precentral sulcus), others have failed to identify such associations. One method used by many researchers to determine structural grey matter asymmetries is voxel based morphometry (VBM). However, it has recently been suggested that the standard VBM protocol might not be ideal to assess structural grey matter asymmetries, as it establishes accurate voxel-wise correspondence across individuals but not across both hemispheres. This could potentially lead to biased and incoherent results. Recently, a new toolbox specifically geared at assessing structural asymmetries and involving accurate voxel-wise correspondence across hemispheres has been published [F. Kurth, C. Gaser, E. Luders. A 12-step user guide for analyzing voxel-wise gray matter asymmetries in statistical parametric mapping (SPM), Nat Protoc 10 (2015), 293-304]. Here, we used this new toolbox to re-assess grey matter asymmetry differences in left- vs. right-handers and linked them to quantitative measures of hand preference and hand skill. While we identified several significant left-right asymmetries in the overall sample, no difference between left- and right-handers reached significance after correction for multiple comparisons. These findings indicate that the structural brain correlates of handedness are unlikely to be rooted in macroscopic grey matter area differences that can be assessed with VBM. Future studies should focus on other potential structural correlates of handedness, e.g. structural white matter asymmetries.

  13. Voxel size dependency, reproducibility and sensitivity of an in vivo bone loading estimation algorithm.

    Science.gov (United States)

    Christen, Patrik; Schulte, Friederike A; Zwahlen, Alexander; van Rietbergen, Bert; Boutroy, Stephanie; Melton, L Joseph; Amin, Shreyasee; Khosla, Sundeep; Goldhahn, Jörg; Müller, Ralph

    2016-01-01

    A bone loading estimation algorithm was previously developed that provides in vivo loading conditions required for in vivo bone remodelling simulations. The algorithm derives a bone's loading history from its microstructure as assessed by high-resolution (HR) computed tomography (CT). This reverse engineering approach showed accurate and realistic results based on micro-CT and HR-peripheral quantitative CT images. However, its voxel size dependency, reproducibility and sensitivity still need to be investigated, which is the purpose of this study. Voxel size dependency was tested on cadaveric distal radii with micro-CT images scanned at 25 µm and downscaled to 50, 61, 75, 82, 100, 125 and 150 µm. Reproducibility was calculated with repeated in vitro as well as in vivo HR-pQCT measurements at 82 µm. Sensitivity was defined using HR-pQCT images from women with fracture versus non-fracture, and low versus high bone volume fraction, expecting similar and different loading histories, respectively. Our results indicate that the algorithm is voxel size independent within an average (maximum) error of 8.2% (32.9%) at 61 µm, but that the dependency increases considerably at voxel sizes bigger than 82 µm. In vitro and in vivo reproducibility are up to 4.5% and 10.2%, respectively, which is comparable to other in vitro studies and slightly higher than in other in vivo studies. Subjects with different bone volume fraction were clearly distinguished but not subjects with and without fracture. This is in agreement with bone adapting to customary loading but not to fall loads. We conclude that the in vivo bone loading estimation algorithm provides reproducible, sensitive and fairly voxel size independent results at up to 82 µm, but that smaller voxel sizes would be advantageous.

  14. Intrinsic dependencies of CT radiomic features on voxel size and number of gray levels.

    Science.gov (United States)

    Shafiq-Ul-Hassan, Muhammad; Zhang, Geoffrey G; Latifi, Kujtim; Ullah, Ghanim; Hunt, Dylan C; Balagurunathan, Yoganand; Abdalah, Mahmoud Abrahem; Schabath, Matthew B; Goldgof, Dmitry G; Mackin, Dennis; Court, Laurence Edward; Gillies, Robert James; Moros, Eduardo Gerardo

    2017-03-01

    Many radiomics features were originally developed for non-medical imaging applications and therefore original assumptions may need to be reexamined. In this study, we investigated the impact of slice thickness and pixel spacing (or pixel size) on radiomics features extracted from Computed Tomography (CT) phantom images acquired with different scanners as well as different acquisition and reconstruction parameters. The dependence of CT texture features on gray-level discretization was also evaluated. A texture phantom composed of 10 different cartridges of different materials was scanned on eight different CT scanners from three different manufacturers. The images were reconstructed for various slice thicknesses. For each slice thickness, the reconstruction Field Of View (FOV) was varied to render pixel sizes ranging from 0.39 to 0.98 mm. A fixed spherical region of interest (ROI) was contoured on the images of the shredded rubber cartridge and the 3D printed, 20% fill, acrylonitrile butadiene styrene plastic cartridge (ABS20) for all phantom imaging sets. Radiomic features were extracted from the ROIs using an in-house program. Features categories were: shape (10), intensity (16), GLCM (24), GLZSM (11), GLRLM (11), and NGTDM (5), fractal dimensions (8) and first-order wavelets (128), for a total of 213 features. Voxel-size resampling was performed to investigate the usefulness of extracting features using a suitably chosen voxel size. Acquired phantom image sets were resampled to a voxel size of 1 × 1 × 2 mm(3) using linear interpolation. Image features were therefore extracted from resampled and original datasets and the absolute value of the percent coefficient of variation (%COV) for each feature was calculated. Based on the %COV values, features were classified in 3 groups: (1) features with large variations before and after resampling (%COV >50); (2) features with diminished variation (%COV variation (%COV definitions to include voxel size. Original and

  15. Voxel-based MRI intensitometry reveals extent of cerebral white matter pathology in amyotrophic lateral sclerosis.

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    Viktor Hartung

    Full Text Available Amyotrophic lateral sclerosis (ALS is characterized by progressive loss of upper and lower motor neurons. Advanced MRI techniques such as diffusion tensor imaging have shown great potential in capturing a common white matter pathology. However the sensitivity is variable and diffusion tensor imaging is not yet applicable to the routine clinical environment. Voxel-based morphometry (VBM has revealed grey matter changes in ALS, but the bias-reducing algorithms inherent to traditional VBM are not optimized for the assessment of the white matter changes. We have developed a novel approach to white matter analysis, namely voxel-based intensitometry (VBI. High resolution T1-weighted MRI was acquired at 1.5 Tesla in 30 ALS patients and 37 age-matched healthy controls. VBI analysis at the group level revealed widespread white matter intensity increases in the corticospinal tracts, corpus callosum, sub-central, frontal and occipital white matter tracts and cerebellum. VBI results correlated with disease severity (ALSFRS-R and patterns of cerebral involvement differed between bulbar- and limb-onset. VBI would be easily translatable to the routine clinical environment, and once optimized for individual analysis offers significant biomarker potential in ALS.

  16. Regional White Matter Decreases in Alzheimer's Disease Using Optimized Voxel-Based Morphometry

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    Shuyu Li; Fang Pu; Feng Shi; Sheng Xie; Yinhua Wang; Tianzi Jiang (Dept. of Bioengineering, Beijing Univ. of Aeronautics and Astronautics, Beijing (China))

    2008-02-15

    Background: Most studies that attempt to clarify structural abnormalities related to functional disconnection in patients with Alzheimer's disease (AD) have focused on exploring pathological changes in cortical gray matter. However, white matter fibers connecting these cerebral areas may also be abnormal. Purpose: To investigate the regional changes of white matter volume in patients with AD compared to healthy subjects. Material and Methods: White matter volume changes in whole-brain magnetic resonance images acquired from 19 patients with AD and 20 healthy subjects (control group) were observed using the optimized voxel-based morphometry (VBM) method. In addition, the corpus callosum (CC) of AD patients and the control group was investigated further by outlining manually the boundary of the CC on a midsagittal slice. Each area of the CC was then corrected by dividing each subject's intracranial area in the midsagittal plane. Results: Compared with the control group, AD patients showed significantly reduced white matter volumes in the posterior part of the CC and the temporal lobe in the left and right hemispheres. Moreover, the voxel showing peak statistical difference in the posterior of the CC was left sided. The five subdivisions of the CC were also significantly smaller among the AD patients relative to the control group. Conclusion: Our findings suggest that these abnormalities in white matter regions may contribute to the functional disconnections in AD

  17. Regional White Matter Decreases in Alzheimer's Disease Using Optimized Voxel-Based Morphometry

    Energy Technology Data Exchange (ETDEWEB)

    Shuyu Li; Fang Pu; Feng Shi; Sheng Xie; Yinhua Wang; Tianzi Jiang [Dept. of Bioengineering, Beijing Univ. of Aeronautics and Astronautics, Beijing (China)

    2008-02-15

    Background: Most studies that attempt to clarify structural abnormalities related to functional disconnection in patients with Alzheimer's disease (AD) have focused on exploring pathological changes in cortical gray matter. However, white matter fibers connecting these cerebral areas may also be abnormal. Purpose: To investigate the regional changes of white matter volume in patients with AD compared to healthy subjects. Material and Methods: White matter volume changes in whole-brain magnetic resonance images acquired from 19 patients with AD and 20 healthy subjects (control group) were observed using the optimized voxel-based morphometry (VBM) method. In addition, the corpus callosum (CC) of AD patients and the control group was investigated further by outlining manually the boundary of the CC on a midsagittal slice. Each area of the CC was then corrected by dividing each subject's intracranial area in the midsagittal plane. Results: Compared with the control group, AD patients showed significantly reduced white matter volumes in the posterior part of the CC and the temporal lobe in the left and right hemispheres. Moreover, the voxel showing peak statistical difference in the posterior of the CC was left sided. The five subdivisions of the CC were also significantly smaller among the AD patients relative to the control group. Conclusion: Our findings suggest that these abnormalities in white matter regions may contribute to the functional disconnections in AD.

  18. The effect of voxel size on the measurement of mandibular thickness in cone-beam computed tomography

    Directory of Open Access Journals (Sweden)

    Ehsan Hekmatian

    2014-01-01

    Full Text Available Background: Cone-beam computed tomography (CBCT is a new imaging technology that has been widely used in implantology, oral and maxillofacial surgery and orthodontics. This method provides 3-D images that are composed of voxel, which is the smallest image unit, and determines image resolution. Smaller voxel is associated with the higher resolution and also greater radiation exposure. This study was aimed to find out the effect of voxel size on the measurement of mandibular thickness. Materials and Methods: Using voxel sizes of 0.30 mm and 0.15 mm, two CBCT protocols (protocol 1: Field of view (FOV of 15 cm, 85 kVp, 42 mAs, 0.15 mm voxel, 14 s scan time; protocol 2: FOV of 15 cm, 85 kVp, 10 mAs, 0.30 mm voxel, 14 s scan time were carried out on 16 dry human mandibles with permanent dentition. Mandibular thickness was measured at seven different sites (midline region, bilateral canine regions, bilateral mental foramen regions and bilateral molar regions. Analysis of variance was used for analysis of data using the Statistical Package for the Social Sciences version 20 (SPSS Inc., Chicago, IL, USA. P 0.05. Conclusion: Considering the insignificant differences of the mandibular thickness measurements using different voxel sizes, it would be more reasonable to use 0.30 mm voxel size instead of 0.15 mm voxel size to avoid unnecessary radiation exposure.

  19. Regional gray matter abnormalities in patients with schizophrenia determined with optimized voxel-based morphometry

    Science.gov (United States)

    Guo, XiaoJuan; Yao, Li; Jin, Zhen; Chen, Kewei

    2006-03-01

    This study examined regional gray matter abnormalities across the whole brain in 19 patients with schizophrenia (12 males and 7 females), comparing with 11 normal volunteers (7 males and 4 females). The customized brain templates were created in order to improve spatial normalization and segmentation. Then automated preprocessing of magnetic resonance imaging (MRI) data was conducted using optimized voxel-based morphometry (VBM). The statistical voxel based analysis was implemented in terms of two-sample t-test model. Compared with normal controls, regional gray matter concentration in patients with schizophrenia was significantly reduced in the bilateral superior temporal gyrus, bilateral middle frontal and inferior frontal gyrus, right insula, precentral and parahippocampal areas, left thalamus and hypothalamus as well as, however, significant increases in gray matter concentration were not observed across the whole brain in the patients. This study confirms and extends some earlier findings on gray matter abnormalities in schizophrenic patients. Previous behavior and fMRI researches on schizophrenia have suggested that cognitive capacity decreased and self-conscious weakened in schizophrenic patients. These regional gray matter abnormalities determined through structural MRI with optimized VBM may be potential anatomic underpinnings of schizophrenia.

  20. Diffuse Decreased Gray Matter in Patients with Idiopathic Craniocervical Dystonia: a Voxel-Based Morphometry Study

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    Camila Callegari Piccinin

    2015-01-01

    Full Text Available Background: Recent studies have addressed the role of structures other than the basal ganglia in the pathophysiology of craniocervical dystonia. Neuroimaging studies have attempted to identify structural abnormalities in craniocervical dystonia but a clear pattern of alteration has not been established. We performed whole brain evaluation using voxel-based morphometry to identify patterns of gray matter changes in craniocervical dystonia.Methods: We compared 27 patients with craniocervical dystonia matched in age and gender to 54 healthy controls. Voxel-based morphometry was used to compare gray matter volumes. We created a two-sample t-test corrected for subjects’ age and we tested with a level of significance of p<0.001 and false discovery rate correction (p<0.05. Results: Voxel-based morphometry demonstrated significant reductions of gray matter using p<0.001 in the cerebellar vermis IV/V, bilaterally in the superior frontal gyrus, precuneus, anterior cingulate and paracingulate, insular cortex, lingual gyrus and calcarine fissure; in the left hemisphere in the supplemementary motor area (SMA, inferior frontal gyrus, inferior parietal gyrus, temporal pole, supramarginal gyrus, rolandic operculum , hippocampus, middle occipital gyrus, cerebellar lobules IV/V, superior and middle temporal gyri; in the right hemisphere, the middle cingulate and precentral gyrus. Our study did not report any significant result using the false discovery rate correction. We also detected correlations between gray matter volume and age, disease duration, duration of botulinum toxin treatment and the Marsden-Fahn dystonia scale scores.Conclusions: We detected large clusters of gray matter changes chiefly in structures primarily involved in sensorimotor integration, motor planning, visuospatial function and emotional processing.

  1. A voxel-based morphometry study of grey matter loss in fragile X-associated tremor/ataxia syndrome.

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    Hashimoto, Ryu-ichiro; Javan, Alireza K; Tassone, Flora; Hagerman, Randi J; Rivera, Susan M

    2011-03-01

    Fragile X-associated tremor/ataxia syndrome is a neurodegenerative disorder that primarily affects older male premutation carriers of the fragile X mental retardation gene. Although its core symptoms are mainly characterized by motor problems such as intention tremor and gait ataxia, cognitive decline and psychiatric problems are also commonly observed. Past radiological and histological approaches have focused on prominent neurodegenerative changes in specific brain structures including the cerebellum and limbic areas. However, quantitative investigations of the regional structural abnormalities have not been performed over the whole brain. In this study, we adopted the voxel-based morphometry method together with regions of interest analysis for the cerebellum to examine the pattern of regional grey matter change in the male premutation carriers with and without fragile X-associated tremor/ataxia syndrome. In a comparison with healthy controls, we found striking grey matter loss of the patients with fragile X-associated tremor/ataxia syndrome in multiple regions over the cortical and subcortical structures. In the cerebellum, the anterior lobe and the superior posterior lobe were profoundly reduced in both vermis and hemispheres. In the cerebral cortex, clusters of highly significant grey matter reduction were found in the extended areas in the medial surface of the brain, including the dorsomedial prefrontal cortex, anterior cingulate cortex and precuneus. The other prominent grey matter loss was found in the lateral prefrontal cortex, orbitofrontal cortex, amygdala and insula. Although the voxel-wise comparison between the asymptomatic premutation group and healthy controls did not reach significant difference, a regions of interest analysis revealed significant grey matter reduction in anterior subregions of the cerebellar vermis and hemisphere in the asymptomatic premutation group. Correlation analyses using behavioural scales of the premutation groups showed

  2. Dyslexia and voxel-based morphometry: correlations between five behavioural measures of dyslexia and gray and white matter volumes

    NARCIS (Netherlands)

    Tamboer, P.; Scholte, H.S.; Vorst, H.C.M.

    2015-01-01

    In voxel-based morphometry studies of dyslexia, the relation between causal theories of dyslexia and gray matter (GM) and white matter (WM) volume alterations is still under debate. Some alterations are consistently reported, but others failed to reach significance. We investigated GM alterations in

  3. Dyslexia and Voxel-Based Morphometry: Correlations between Five Behavioural Measures of Dyslexia and Gray and White Matter Volumes

    Science.gov (United States)

    Tamboer, Peter; Scholte, H. Steven; Vorst, Harrie C. M.

    2015-01-01

    In voxel-based morphometry studies of dyslexia, the relation between causal theories of dyslexia and gray matter (GM) and white matter (WM) volume alterations is still under debate. Some alterations are consistently reported, but others failed to reach significance. We investigated GM alterations in a large sample of Dutch students (37 dyslexics…

  4. Accuracy in the diagnosis of vertical root fractures, external root resorptions, and root perforations using cone-beam computed tomography with different voxel sizes of acquisition

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    Fernanda Paula Bragatto

    2016-01-01

    Conclusions: Voxel size 0.125 mm produced images with the best resolution without increasing radiation levels to the patient when compared to voxel sizes 0.200 and 0.250 mm. Voxel sizes 0.300 and 0.400 mm should be avoided in the identification of root alterations.

  5. In vitro comparison of cone beam computed tomography with different voxel sizes for detection of simulated external root resorption.

    Science.gov (United States)

    Neves, Frederico S; de Freitas, Deborah Q; Campos, Paulo S F; de Almeida, Solange M; Haiter-Neto, Francisco

    2012-09-01

    The present study compared the efficacy of cone beam computed tomography using different voxel sizes in the diagnosis of simulated external root resorption. The presence or absence of simulated defects on buccal, mesial and distal root surfaces of 20 premolars was evaluated. The defects were small (0.26 mm in diameter and 0.08 mm deep), medium (0.62 mm in diameter and 0.19 mm deep) and large (1.05 mm in diameter and 0.24 mm deep), equally distributed on each root surface. Images were obtained using Classic i-CAT cone beam computed tomography with different voxel sizes: 0.12, 0.20, 0.25 and 0.30 mm. Five oral radiologists evaluated the images. Accuracy, sensitivity, specificity, positive and negative predictive values were determined. The sensitivity decreased and specificity increased as voxel size increased. Accuracy values were the highest for the smallest voxel size (0.12 mm). The results for voxel sizes 0.20 mm and 0.25 mm were similar. Positive and negative predictive values were similar in all protocols, except with 0.30 mm, in which they were the lowest. In conclusion, external root resorption was more easily diagnosed when a smaller voxel size was used.

  6. Gray matter abnormalities in Internet addiction: A voxel-based morphometry study

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    Zhou Yan, E-mail: clare1475@hotmail.com [Department of Radiology, RenJi Hospital, Jiao Tong University Medical School, Shanghai 200127 (China); Lin Fuchun, E-mail: fclin@wipm.ac.cn [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Du Yasong, E-mail: yasongdu@yahoo.com.cn [Department of Child and Adolescent Psychiatry Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai 200030 (China); Qin Lingdi, E-mail: flyingfool838@hotmail.com [Department of Radiology, RenJi Hospital, Jiao Tong University Medical School, Shanghai 200127 (China); Zhao Zhimin, E-mail: zmzsky@163.com [Department of Child and Adolescent Psychiatry Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai 200030 (China); Xu Jianrong, E-mail: xujianr@hotmail.com [Department of Radiology, RenJi Hospital, Jiao Tong University Medical School, Shanghai 200127 (China); Lei Hao, E-mail: leihao@wipm.ac.cn [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)

    2011-07-15

    Background: This study aims to investigate brain gray matter density (GMD) changes in adolescents with Internet addiction (IA) using voxel-based morphometry (VBM) analysis on high-resolution T1-weighted structural magnetic resonance images. Methods: Eighteen IA adolescents and 15 age- and gender-matched healthy controls took part in this study. High-resolution T1-weighted magnetic resonance imaging scans were performed on the two groups. VBM analysis was used to compare the GMD between the two groups. Results: Compared with healthy controls, IA adolescents had lower GMD in the left anterior cingulate cortex, left posterior cingulate cortex, left insula, and left lingual gyrus. Conclusions: Our findings suggested that brain structural changes were present in IA adolescents, and this finding may provide a new insight into the pathogenesis of IA.

  7. Brain Gray Matter Atrophy after Spinal Cord Injury: A Voxel-Based Morphometry Study

    Directory of Open Access Journals (Sweden)

    Nan Chen

    2017-04-01

    Full Text Available The aim of this study was to explore possible changes in whole brain gray matter volume (GMV after spinal cord injury (SCI using voxel-based morphometry (VBM, and to study their associations with the injury duration, severity, and clinical variables. In total, 21 patients with SCI (10 with complete and 11 with incomplete SCI and 21 age- and sex-matched healthy controls (HCs were recruited. The 3D high-resolution T1-weighted structural images of all subjects were obtained using a 3.0 Tesla MRI system. Disease duration and American Spinal Injury Association (ASIA Scale scores were also obtained from each patient. Voxel-based morphometry analysis was carried out to investigate the differences in GMV between patients with SCI and HCs, and between the SCI sub-groups. Associations between GMV and clinical variables were also analyzed. Compared with HCs, patients with SCI showed significant GMV decrease in the dorsal anterior cingulate cortex, bilateral anterior insular cortex, bilateral orbital frontal cortex (OFC, and right superior temporal gyrus. No significant difference in GMV in these areas was found either between the complete and incomplete SCI sub-groups, or between the sub-acute (duration <1 year and chronic (duration >1 year sub-groups. Finally, the GMV of the right OFC was correlated with the clinical motor scores of left extremities in not only all SCI patients, but especially the CSCI subgroup. In the sub-acute subgroup, we found a significant positive correlation between the dACC GMV and the total clinical motor scores, and a significant negative correlation between right OFC GMV and the injury duration. These findings indicate that SCI can cause remote atrophy of brain gray matter, especially in the salient network. In general, the duration and severity of SCI may be not associated with the degree of brain atrophy in total SCI patients, but there may be associations between them in subgroups.

  8. Voxel-based analysis of grey and white matter degeneration in cervical spondylotic myelopathy.

    Science.gov (United States)

    Grabher, Patrick; Mohammadi, Siawoosh; Trachsler, Aaron; Friedl, Susanne; David, Gergely; Sutter, Reto; Weiskopf, Nikolaus; Thompson, Alan J; Curt, Armin; Freund, Patrick

    2016-04-20

    In this prospective study, we made an unbiased voxel-based analysis to investigate above-stenosis spinal degeneration and its relation to impairment in patients with cervical spondylotic myelopathy (CSM). Twenty patients and 18 controls were assessed with high-resolution MRI protocols above the level of stenosis. Cross-sectional areas of grey matter (GM), white matter (WM), and posterior columns (PC) were measured to determine atrophy. Diffusion indices assessed tract-specific integrity of PC and lateral corticospinal tracts (CST). Regression analysis was used to reveal relationships between MRI measures and clinical impairment. Patients showed mainly sensory impairment. Atrophy was prominent within the cervical WM (13.9%, p = 0.004), GM (7.2%, p = 0.043), and PC (16.1%, p = 0.005). Fractional anisotropy (FA) was reduced in the PC (-11.98%, p = 0.006) and lateral CST (-12.96%, p = 0.014). In addition, radial (+28.47%, p = 0.014), axial (+14.72%, p = 0.005), and mean (+16.50%, p = 0.001) diffusivities were increased in the PC. Light-touch score was associated with atrophy (R(2) = 0.3559, p = 0.020) and FA (z score 3.74, p = 0.003) in the PC, as was functional independence and FA in the lateral CST (z score 3.68, p = 0.020). This study demonstrates voxel-based degeneration far above the stenosis at a level not directly affected by the compression and provides unbiased readouts of tract-specific changes that relate to impairment.

  9. Early Gray-Matter and White-Matter Concentration in Infancy Predict Later Language Skills: A Whole Brain Voxel-Based Morphometry Study

    Science.gov (United States)

    Can, Dilara Deniz; Richards, Todd; Kuhl, Patricia K.

    2013-01-01

    Magnetic Resonance Imaging (MRI) brain scans were obtained from 19 infants at 7 months. Expressive and receptive language performance was assessed at 12 months. Voxel-based morphometry (VBM) identified brain regions where gray-matter and white-matter concentrations at 7 months correlated significantly with children's language scores at 12 months.…

  10. Early Gray-Matter and White-Matter Concentration in Infancy Predict Later Language Skills: A Whole Brain Voxel-Based Morphometry Study

    Science.gov (United States)

    Can, Dilara Deniz; Richards, Todd; Kuhl, Patricia K.

    2013-01-01

    Magnetic Resonance Imaging (MRI) brain scans were obtained from 19 infants at 7 months. Expressive and receptive language performance was assessed at 12 months. Voxel-based morphometry (VBM) identified brain regions where gray-matter and white-matter concentrations at 7 months correlated significantly with children's language scores at 12 months.…

  11. Regional gray matter density associated with emotional intelligence: evidence from voxel-based morphometry.

    Science.gov (United States)

    Takeuchi, Hikaru; Taki, Yasuyuki; Sassa, Yuko; Hashizume, Hiroshi; Sekiguchi, Atsushi; Fukushima, Ai; Kawashima, Ryuta

    2011-09-01

    Emotional Intelligence (EI) is the ability to monitor one's own and others' emotions and the ability to use the gathered information to guide one's thinking and action. EI is thought to be important for social life making it a popular subject of research. However, despite the existence of previous functional imaging studies on EI, the relationship between regional gray matter morphology and EI has never been investigated. We used voxel-based morphometry (VBM) and a questionnaire (Emotional Intelligence Scale) to measure EI to identify the gray matter correlates of each factor of individual EI (Intrapersonal factor, Interpersonal factor, Situation Management factor). We found significant negative relationships between the Intrapersonal factor and regional gray matter density (rGMD) (1-a) in an anatomical cluster that included the right anterior insula, (1-b) in the right cerebellum, (1-c) in an anatomical cluster that extends from the cuneus to the precuneus, (1-d) and in an anatomical cluster that extends from the medial prefrontal cortex to the left lateral fronto-polar cortex. We also found significant positive correlations between the Interpersonal factor and rGMD in the right superior temporal sulcus, and significant negative correlations between the Situation Management factor and rGMD in the ventromedial prefrontal cortex. These findings suggest that each factor of EI in healthy young people is related to the specific brain regions known to be involved in the networks of social cognition and self-related recognition, and in the somatic marker circuitry.

  12. A voxelation-corrected non-stationary 3D cluster-size test based on random field theory.

    Science.gov (United States)

    Li, Huanjie; Nickerson, Lisa D; Zhao, Xuna; Nichols, Thomas E; Gao, Jia-Hong

    2015-09-01

    Cluster-size tests (CSTs) based on random field theory (RFT) are commonly adopted to identify significant differences in brain images. However, the use of RFT in CSTs rests on the assumption of uniform smoothness (stationarity). When images are non-stationary, CSTs based on RFT will likely lead to increased false positives in smooth regions and reduced power in rough regions. An adjustment to the cluster size according to the local smoothness at each voxel has been proposed for the standard test based on RFT to address non-stationarity, however, this technique requires images with a large degree of spatial smoothing, large degrees of freedom and high intensity thresholding. Recently, we proposed a voxelation-corrected 3D CST based on Gaussian random field theory that does not place constraints on the degree of spatial smoothness. However, this approach is only applicable to stationary images, requiring further modification to enable use for non-stationary images. In this study, we present modifications of this method to develop a voxelation-corrected non-stationary 3D CST based on RFT. Both simulated and real data were used to compare the voxelation-corrected non-stationary CST to the standard cluster-size adjusted non-stationary CST based on RFT and the voxelation-corrected stationary CST. We found that voxelation-corrected stationary CST is liberal for non-stationary images and the voxelation-corrected non-stationary CST performs better than cluster-size adjusted non-stationary CST based on RFT under low smoothness, low intensity threshold and low degrees of freedom. Published by Elsevier Inc.

  13. A 12-step user guide for analyzing voxel-wise gray matter asymmetries in statistical parametric mapping (SPM).

    Science.gov (United States)

    Kurth, Florian; Gaser, Christian; Luders, Eileen

    2015-02-01

    Voxel-based morphometry (VBM) has been proven capable of capturing cerebral gray matter asymmetries with a high (voxel-wise) regional specificity. However, a standardized reference on how to conduct voxel-wise asymmetry analyses is missing. This protocol provides the scientific community with a carefully developed guide describing, in 12 distinct steps, how to take structural images from data pre-processing, via statistical analysis, to the final interpretation of the significance maps. Key adaptations compared with the standard VBM workflow involve establishing a voxel-wise hemispheric correspondence, capturing the direction and degree of asymmetry and preventing a blurring of information across hemispheres. The workflow incorporates the most recent methodological developments, including high-dimensional spatial normalization and partial volume estimations. Although the protocol is primarily designed to enable relatively inexperienced users to conduct a voxel-based asymmetry analysis on their own, it may also be useful to experienced users who wish to efficiently adapt their existing scripts or pipelines.

  14. Gray Matter Volume Decreases in Elderly Patients with Schizophrenia: A Voxel-based Morphometry Study

    Science.gov (United States)

    Schuster, Caroline; Schuller, Anne Marie; Paulos, Carlos; Namer, Izzie; Pull, Charles; Danion, Jean Marie; Foucher, Jack René

    2012-01-01

    Background: Aged patients (>50 years old) with residual schizophrenic symptoms differ from young patients. They represent a subpopulation with a more unfavorable Kraepelinian course and have an increased risk (up to 30%) for dementia of unknown origin. However, our current understanding of age-related brain changes in schizophrenia is derived from studies that included less than 17% of patients who were older than 50 years of age. This study investigated the anatomical distribution of gray matter (GM) brain deficits in aged patients with ongoing schizophrenia. Methods: Voxel-based morphometry was applied to 3D-T1 magnetic resonance images obtained from 27 aged patients with schizophrenia (mean age of 60 years) and 40 age-matched normal controls. Results: Older patients with schizophrenia showed a bilateral reduction of GM volume in the thalamus, the prefrontal cortex, and in a large posterior region centered on the occipito-temporo-parietal junction. Only the latter region showed accelerated GM volume loss with increasing age. None of these results could be accounted for by institutionalization, antipsychotic medication, or cognitive scores. Conclusions: This study replicated most common findings in patients with schizophrenia with regard to thalamic and frontal GM deficits. However, it uncovered an unexpected large region of GM atrophy in the posterior tertiary cortices. The latter observation may be specific to this aged and chronically symptomatic subpopulation, as atrophy in this region is rarely reported in younger patients and is accelerated with age. PMID:21205677

  15. Grey matter abnormalities in untreated hyperthyroidism: A voxel-based morphometry study using the DARTEL approach

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    Zhang, Wei, E-mail: will.zhang.1111@gmail.com [Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Department of Radiology, Sichuan Provincial Corps Hospital, Chinese People' s Armed Police Forces, Leshan 614000 (China); Song, Lingheng, E-mail: songlh1023@hotmail.com [Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Department of Radiology, No. 324 Hospital of PLA, Chongqing 400020 (China); Yin, Xuntao, E-mail: xuntaoyin@gmail.com [Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Zhang, Jiuquan, E-mail: jiuquanzhang@yahoo.com [Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Liu, Chen, E-mail: cqliuchen@foxmail.com [Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Wang, Jian, E-mail: wangjian_811@yahoo.com [Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Zhou, Daiquan, E-mail: zhoudq77@sina.com [Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Chen, Bing, E-mail: chenbing3@medmail.com.cn [Department of Endocrinology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Lii, Haitao, E-mail: haitaolii023@gmail.com [Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China)

    2014-01-15

    Objective: Hyperthyroidism is frequently associated with pronounced neuropsychiatric symptoms such as impulsiveness, irritability, poor concentration, and memory impairments. Functional neuroimaging has revealed changes in cerebral metabolism in hyperthyroidism, but regional changes in cortical morphology associated with specific neurological deficits have not been studied so far. To investigate the pathophysiology underlying hyperthyroid-associated neural dysfunction, we compared grey matter volume (GMV) between adult hyperthyroid patients and matched healthy controls using voxel-based morphometry (VBM). Materials and methods: High resolution 3D T1-weighted images were acquired by 3T MRI from 51 hyperthyroid patients and 51 controls. VBM analysis was performed using SPM8. Correlations between regional GMV and both serum free thyroid hormone (TH) concentrations and disease duration were assessed by multiple regression analysis. Results: Compared to controls, GM volumes in the bilateral hippocampus, parahippocampal gyrus, calcarine, lingual gyrus, and left temporal pole were lower and bilateral supplementary motor area GMV higher in hyperthyroid patients. Serum free triiodothyronine (FT3) concentration was negatively correlated with the normalized regional volume (NRV) of the left parahippocampal gyrus and serum free thyroxine (FT4) concentration negatively correlated with the NRV of the left hippocampus and right parahippocampal gyrus. Disease duration was negatively correlated with the NRV of the left hippocampus, bilateral parahippocampal gyrus, and left temporal pole. Conclusion: Hyperthyroid patients exhibited reduced GMV in regions associated with memory, attention, emotion, vision, and motor planning. Negative correlations between GMV and both free TH and disease duration suggest that chronic TH elevation induces abnormalities in the adult cortex.

  16. Effect of micro-computed tomography voxel size and segmentation method on trabecular bone microstructure measures in mice.

    Science.gov (United States)

    Christiansen, Blaine A

    2016-12-01

    Micro-computed tomography (μCT) is currently the gold standard for determining trabecular bone microstructure in small animal models. Numerous parameters associated with scanning and evaluation of μCT scans can strongly affect morphologic results obtained from bone samples. However, the effect of these parameters on specific trabecular bone outcomes is not well understood. This study investigated the effect of μCT scanning with nominal voxel sizes between 6-30 μm on trabecular bone outcomes quantified in mouse vertebral body trabecular bone. Additionally, two methods for determining a global segmentation threshold were compared: based on qualitative assessment of 2D images, or based on quantitative assessment of image histograms. It was found that nominal voxel size had a strong effect on several commonly reported trabecular bone parameters, in particular connectivity density, trabecular thickness, and bone tissue mineral density. Additionally, the two segmentation methods provided similar trabecular bone outcomes for scans with small nominal voxel sizes, but considerably different outcomes for scans with larger voxel sizes. The Qualitatively Selected segmentation method more consistently estimated trabecular bone volume fraction (BV/TV) and trabecular thickness across different voxel sizes, but the Histogram segmentation method more consistently estimated trabecular number, trabecular separation, and structure model index. Altogether, these results suggest that high-resolution scans be used whenever possible to provide the most accurate estimation of trabecular bone microstructure, and that the limitations of accurately determining trabecular bone outcomes should be considered when selecting scan parameters and making conclusions about inter-group variance or between-group differences in studies of trabecular bone microstructure in small animals.

  17. Regional grey matter structure differences between transsexuals and healthy controls--a voxel based morphometry study.

    Directory of Open Access Journals (Sweden)

    Lajos Simon

    Full Text Available Gender identity disorder (GID refers to transsexual individuals who feel that their assigned biological gender is incongruent with their gender identity and this cannot be explained by any physical intersex condition. There is growing scientific interest in the last decades in studying the neuroanatomy and brain functions of transsexual individuals to better understand both the neuroanatomical features of transsexualism and the background of gender identity. So far, results are inconclusive but in general, transsexualism has been associated with a distinct neuroanatomical pattern. Studies mainly focused on male to female (MTF transsexuals and there is scarcity of data acquired on female to male (FTM transsexuals. Thus, our aim was to analyze structural MRI data with voxel based morphometry (VBM obtained from both FTM and MTF transsexuals (n = 17 and compare them to the data of 18 age matched healthy control subjects (both males and females. We found differences in the regional grey matter (GM structure of transsexual compared with control subjects, independent from their biological gender, in the cerebellum, the left angular gyrus and in the left inferior parietal lobule. Additionally, our findings showed that in several brain areas, regarding their GM volume, transsexual subjects did not differ significantly from controls sharing their gender identity but were different from those sharing their biological gender (areas in the left and right precentral gyri, the left postcentral gyrus, the left posterior cingulate, precuneus and calcarinus, the right cuneus, the right fusiform, lingual, middle and inferior occipital, and inferior temporal gyri. These results support the notion that structural brain differences exist between transsexual and healthy control subjects and that majority of these structural differences are dependent on the biological gender.

  18. Structural differences in gray matter between glider pilots and non-pilots. A voxel based morphometry study.

    Directory of Open Access Journals (Sweden)

    Tosif eAhamed

    2014-11-01

    Full Text Available Glider flying is a unique skill that requires pilots to control an aircraft at high speeds in three dimensions and amidst frequent full body rotations. In the present study we investigated the neural correlates of flying a glider using voxel-based morphometry (VBM. The comparison between gray matter densities of 15 glider pilots and a control group of 15 non-pilots exhibited significant gray matter density increases in left ventral premotor cortex, anterior cingulate cortex and the supplementary eye field. We posit that the identified regions might be associated with cognitive and motor processes related to flying such as joystick control, visuo-vestibular interaction and oculomotor control.

  19. Grey matter, an endophenotype for schizophrenia? A voxel-based morphometry study in siblings of patients with schizophrenia

    Science.gov (United States)

    van der Velde, Jorien; Gromann, Paula M.; Swart, Marte; de Haan, Lieuwe; Wiersma, Durk; Bruggeman, Richard; Krabbendam, Lydia; Aleman, André

    2015-01-01

    Background Grey matter, both volume and concentration, has been proposed as an endophenotype for schizophrenia given a number of reports of grey matter abnormalities in relatives of patients with schizophrenia. However, previous studies on grey matter abnormalities in relatives have produced inconsistent results. The aim of the present study was to examine grey matter differences between controls and siblings of patients with schizophrenia and to examine whether the age, genetic loading or subclinical psychotic symptoms of selected individuals could explain the previously reported inconsistencies. Methods We compared the grey matter volume and grey matter concentration of healthy siblings of patients with schizophrenia and healthy controls matched for age, sex and education using voxel-based morphometry (VBM). Furthermore, we selected subsamples based on age (< 30 yr), genetic loading and subclinical psychotic symptoms to examine whether this would lead to different results. Results We included 89 siblings and 69 controls in our study. The results showed that siblings and controls did not differ significantly on grey matter volume or concentration. Furthermore, specifically selecting participants based on age, genetic loading or subclinical psychotic symptoms did not alter these findings. Limitations The main limitation was that subdividing the sample resulted in smaller samples for the subanalyses. Furthermore, we used MRI data from 2 different scanner sites. Conclusion These results indicate that grey matter measured through VBM might not be a suitable endophenotype for schizophrenia. PMID:25768029

  20. Sparse and Adaptive Diffusion Dictionary (SADD) for recovering intra-voxel white matter structure.

    Science.gov (United States)

    Aranda, Ramon; Ramirez-Manzanares, Alonso; Rivera, Mariano

    2015-12-01

    On the analysis of the Diffusion-Weighted Magnetic Resonance Images, multi-compartment models overcome the limitations of the well-known Diffusion Tensor model for fitting in vivo brain axonal orientations at voxels with fiber crossings, branching, kissing or bifurcations. Some successful multi-compartment methods are based on diffusion dictionaries. The diffusion dictionary-based methods assume that the observed Magnetic Resonance signal at each voxel is a linear combination of the fixed dictionary elements (dictionary atoms). The atoms are fixed along different orientations and diffusivity profiles. In this work, we present a sparse and adaptive diffusion dictionary method based on the Diffusion Basis Functions Model to estimate in vivo brain axonal fiber populations. Our proposal overcomes the following limitations of the diffusion dictionary-based methods: the limited angular resolution and the fixed shapes for the atom set. We propose to iteratively re-estimate the orientations and the diffusivity profile of the atoms independently at each voxel by using a simplified and easier-to-solve mathematical approach. As a result, we improve the fitting of the Diffusion-Weighted Magnetic Resonance signal. The advantages with respect to the former Diffusion Basis Functions method are demonstrated on the synthetic data-set used on the 2012 HARDI Reconstruction Challenge and in vivo human data. We demonstrate that improvements obtained in the intra-voxel fiber structure estimations benefit brain research allowing to obtain better tractography estimations. Hence, these improvements result in an accurate computation of the brain connectivity patterns.

  1. Two-tensor streamline tractography through white matter intra-voxel fiber crossings

    DEFF Research Database (Denmark)

    Qazi, Arish Asif; Kindlmann, G; O'Donnell, L;

    2008-01-01

    An inherent drawback of the traditional diffusion tensor model is its limited ability to provide detailed information about multidirectional fiber architecture within a voxel. This leads to erroneous fiber tractography results in locations where fiber bundles cross each other. In this paper, we...

  2. Accelerated cerebral white matter development in preterm infants: a voxel-based morphometry study with diffusion tensor MR imaging

    DEFF Research Database (Denmark)

    Giménez, Mónica; Born, A Peter; Nagy, Zoltan;

    2008-01-01

    stratum. While some earlier findings in preterm infants have suggested developmental delays, the results of this study are more consistent with accelerated white matter development, possibly as a result of increased sensorimotor stimulation in the extrauterine environment. These results are the first......Twenty-seven preterm infants were compared to 10 full-term infants at term equivalent age using a voxel-based analysis of diffusion tensor imaging of the brain. Preterm infants exhibited higher fractional anisotropy values, which may suggest accelerated maturation, in the location of the sagittal...

  3. Local diffusion homogeneity (LDH): an inter-voxel diffusion MRI metric for assessing inter-subject white matter variability.

    Science.gov (United States)

    Gong, Gaolang

    2013-01-01

    Many diffusion parameters and indices (e.g., fractional anisotropy [FA] and mean diffusivity [MD]) have been derived from diffusion magnetic resonance imaging (MRI) data. These parameters have been extensively applied as imaging markers for localizing white matter (WM) changes under various conditions (e.g., development, degeneration and disease). However, the vast majority of the existing parameters is derived from intra-voxel analyses and represents the diffusion properties solely within the voxel unit. Other types of parameters that characterize inter-voxel relationships have been largely overlooked. In the present study, we propose a novel inter-voxel metric referred to as the local diffusion homogeneity (LDH). This metric quantifies the local coherence of water molecule diffusion in a model-free manner. It can serve as an additional marker for evaluating the WM microstructural properties of the brain. To assess the distinguishing features between LDH and FA/MD, the metrics were systematically compared across space and subjects. As an example, both the LDH and FA/MD metrics were applied to measure age-related WM changes. The results indicate that LDH reveals unique inter-subject variability in specific WM regions (e.g., cerebral peduncle, internal capsule and splenium). Furthermore, there are regions in which measurements of age-related WM alterations with the LDH and FA/MD metrics yield discrepant results. These findings suggest that LDH and FA/MD have different sensitivities to specific WM microstructural properties. Taken together, the present study shows that LDH is complementary to the conventional diffusion-MRI markers and may provide additional insights into inter-subject WM variability. Further studies, however, are needed to uncover the neuronal mechanisms underlying the LDH.

  4. Local diffusion homogeneity (LDH: an inter-voxel diffusion MRI metric for assessing inter-subject white matter variability.

    Directory of Open Access Journals (Sweden)

    Gaolang Gong

    Full Text Available Many diffusion parameters and indices (e.g., fractional anisotropy [FA] and mean diffusivity [MD] have been derived from diffusion magnetic resonance imaging (MRI data. These parameters have been extensively applied as imaging markers for localizing white matter (WM changes under various conditions (e.g., development, degeneration and disease. However, the vast majority of the existing parameters is derived from intra-voxel analyses and represents the diffusion properties solely within the voxel unit. Other types of parameters that characterize inter-voxel relationships have been largely overlooked. In the present study, we propose a novel inter-voxel metric referred to as the local diffusion homogeneity (LDH. This metric quantifies the local coherence of water molecule diffusion in a model-free manner. It can serve as an additional marker for evaluating the WM microstructural properties of the brain. To assess the distinguishing features between LDH and FA/MD, the metrics were systematically compared across space and subjects. As an example, both the LDH and FA/MD metrics were applied to measure age-related WM changes. The results indicate that LDH reveals unique inter-subject variability in specific WM regions (e.g., cerebral peduncle, internal capsule and splenium. Furthermore, there are regions in which measurements of age-related WM alterations with the LDH and FA/MD metrics yield discrepant results. These findings suggest that LDH and FA/MD have different sensitivities to specific WM microstructural properties. Taken together, the present study shows that LDH is complementary to the conventional diffusion-MRI markers and may provide additional insights into inter-subject WM variability. Further studies, however, are needed to uncover the neuronal mechanisms underlying the LDH.

  5. Effects of voxel size and iterative reconstruction parameters on the spatial resolution of 99mTc SPECT/CT.

    Science.gov (United States)

    Kappadath, S Cheenu

    2011-11-15

    The purpose of this study was to evaluate the effects of voxel size and iterative reconstruction parameters on the radial and tangential resolution for 99mTc SPECT as a function of radial distance from isocenter. SPECT/CT scans of eight coplanar point sources of size smaller than 1 mm3 containing high concentration 99mTc solution were acquired on a SPECT/CT system with 5/8 inch NaI(Tl) detector and low-energy, high-resolution collimator. The tomographic projection images were acquired in step-and-shoot mode for 360 views over 360° with 250,000 counts per view, a zoom of 2.67, and an image matrix of 256 × 256 pixels that resulted in a 0.9 × 0.9 × 0.9 mm3 SPECT voxel size over 230 mm field-of-view. The projection images were also rebinned to image matrices of 128 × 128 and 64 × 64 to yield SPECT voxel sizes of 1.8 × 1.8 × 1.8 and 3.6 × 3.6 × 3.6 mm3, respectively. The SPECT/CT datasets were reconstructed using the vendor-supplied iterative reconstruction software that incorporated collimator-specific resolution recovery, CT-based attenuation correction, and dual-energy window-based scatter correction using different combinations of iterations and subsets. SPECT spatial resolution was estimated as the full width at half maximum of the radial and tangential profiles through the center of each point source in reconstructed SPECT images. Both radial and tangential resolution improved with higher iterations and subsets, and with smaller voxel sizes. Both radial and tangential resolution also improved with radial distance further away from isocenter. The magnitude of variation decreased for smaller voxel sizes and for higher number of iterations and subsets. Tangential resolution was found not to be equal to the radial resolution, and the nature of the anisotropy depended on the distribution of the radionuclide and on the reconstruction parameters used. The tangential resolution converged faster than the radial resolution, with higher iterations and subsets

  6. Increased Grey Matter Associated with Long-Term Sahaja Yoga Meditation: A Voxel-Based Morphometry Study.

    Directory of Open Access Journals (Sweden)

    Sergio Elías Hernández

    Full Text Available To investigate regional differences in grey matter volume associated with the practice of Sahaja Yoga Meditation.Twenty three experienced practitioners of Sahaja Yoga Meditation and twenty three non-meditators matched on age, gender and education level, were scanned using structural Magnetic Resonance Imaging and their grey matter volume were compared using Voxel-Based Morphometry.Grey matter volume was larger in meditators relative to non-meditators across the whole brain. In addition, grey matter volume was larger in several predominantly right hemispheric regions: in insula, ventromedial orbitofrontal cortex, inferior temporal and parietal cortices as well as in left ventrolateral prefrontal cortex and left insula. No areas with larger grey matter volume were found in non-meditators relative to meditators.The study shows that long-term practice of Sahaja Yoga Meditation is associated with larger grey matter volume overall, and with regional enlargement in several right hemispheric cortical and subcortical brain regions that are associated with sustained attention, self-control, compassion and interoceptive perception. The increased grey matter volume in these attention and self-control mediating regions suggests use-dependent enlargement with regular practice of this meditation.

  7. Increased Grey Matter Associated with Long-Term Sahaja Yoga Meditation: A Voxel-Based Morphometry Study.

    Science.gov (United States)

    Hernández, Sergio Elías; Suero, José; Barros, Alfonso; González-Mora, José Luis; Rubia, Katya

    2016-01-01

    To investigate regional differences in grey matter volume associated with the practice of Sahaja Yoga Meditation. Twenty three experienced practitioners of Sahaja Yoga Meditation and twenty three non-meditators matched on age, gender and education level, were scanned using structural Magnetic Resonance Imaging and their grey matter volume were compared using Voxel-Based Morphometry. Grey matter volume was larger in meditators relative to non-meditators across the whole brain. In addition, grey matter volume was larger in several predominantly right hemispheric regions: in insula, ventromedial orbitofrontal cortex, inferior temporal and parietal cortices as well as in left ventrolateral prefrontal cortex and left insula. No areas with larger grey matter volume were found in non-meditators relative to meditators. The study shows that long-term practice of Sahaja Yoga Meditation is associated with larger grey matter volume overall, and with regional enlargement in several right hemispheric cortical and subcortical brain regions that are associated with sustained attention, self-control, compassion and interoceptive perception. The increased grey matter volume in these attention and self-control mediating regions suggests use-dependent enlargement with regular practice of this meditation.

  8. Mapping grey matter reductions in schizophrenia: an anatomical likelihood estimation analysis of voxel-based morphometry studies.

    Science.gov (United States)

    Fornito, A; Yücel, M; Patti, J; Wood, S J; Pantelis, C

    2009-03-01

    Voxel-based morphometry (VBM) is a popular tool for mapping neuroanatomical changes in schizophrenia patients. Several recent meta-analyses have identified the brain regions in which patients most consistently show grey matter reductions, although they have not examined whether such changes reflect differences in grey matter concentration (GMC) or grey matter volume (GMV). These measures assess different aspects of grey matter integrity, and may therefore reflect different pathological processes. In this study, we used the Anatomical Likelihood Estimation procedure to analyse significant differences reported in 37 VBM studies of schizophrenia patients, incorporating data from 1646 patients and 1690 controls, and compared the findings of studies using either GMC or GMV to index grey matter differences. Analysis of all studies combined indicated that grey matter reductions in a network of frontal, temporal, thalamic and striatal regions are among the most frequently reported in literature. GMC reductions were generally larger and more consistent than GMV reductions, and were more frequent in the insula, medial prefrontal, medial temporal and striatal regions. GMV reductions were more frequent in dorso-medial frontal cortex, and lateral and orbital frontal areas. These findings support the primacy of frontal, limbic, and subcortical dysfunction in the pathophysiology of schizophrenia, and suggest that the grey matter changes observed with MRI may not necessarily result from a unitary pathological process.

  9. A Large Scale (N=400) Investigation of Gray Matter Differences in Schizophrenia Using Optimized Voxel-based Morphometry

    Science.gov (United States)

    Meda, Shashwath A.; Giuliani, Nicole R.; Calhoun, Vince D.; Jagannathan, Kanchana; Schretlen, David J.; Pulver, Anne; Cascella, Nicola; Keshavan, Matcheri; Kates, Wendy; Buchanan, Robert; Sharma, Tonmoy; Pearlson, Godfrey D.

    2008-01-01

    Background Many studies have employed voxel-based morphometry (VBM) of MRI images as an automated method of investigating cortical gray matter differences in schizophrenia. However, results from these studies vary widely, likely due to different methodological or statistical approaches. Objective To use VBM to investigate gray matter differences in schizophrenia in a sample significantly larger than any published to date, and to increase statistical power sufficiently to reveal differences missed in smaller analyses. Methods Magnetic resonance whole brain images were acquired from four geographic sites, all using the same model 1.5T scanner and software version, and combined to form a sample of 200 patients with both first episode and chronic schizophrenia and 200 healthy controls, matched for age, gender and scanner location. Gray matter concentration was assessed and compared using optimized VBM. Results Compared to the healthy controls, schizophrenia patients showed significantly less gray matter concentration in multiple cortical and subcortical regions, some previously unreported. Overall, we found lower concentrations of gray matter in regions identified in prior studies, most of which reported only subsets of the affected areas. Conclusions Gray matter differences in schizophrenia are most comprehensively elucidated using a large, diverse and representative sample. PMID:18378428

  10. Effects of voxel size and iterative reconstruction parameters on the spatial resolution of 99mTc SPECT/CT

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    Kappadath, S. Cheenu

    2011-01-01

    The purpose of this study was to evaluate the effects of voxel size and iterative reconstruction parameters on the radial and tangential resolution for 99mTc SPECT as a function of radial distance from isocenter. SPECT/CT scans of eight coplanar point sources of size smaller than 1 mm3 containing high concentration 99mTc solution were acquired on a SPECT/CT system with 5/8 inch NaI(Tl) detector and low-energy, high-resolution collimator. The tomographic projection images were acquired in step...

  11. Dyslexia and voxel-based morphometry: correlations between five behavioural measures of dyslexia and gray and white matter volumes.

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    Tamboer, Peter; Scholte, H Steven; Vorst, Harrie C M

    2015-10-01

    In voxel-based morphometry studies of dyslexia, the relation between causal theories of dyslexia and gray matter (GM) and white matter (WM) volume alterations is still under debate. Some alterations are consistently reported, but others failed to reach significance. We investigated GM alterations in a large sample of Dutch students (37 dyslexics and 57 non-dyslexics) with two analyses: group differences in local GM and total GM and WM volume and correlations between GM and WM volumes and five behavioural measures. We found no significant group differences after corrections for multiple comparisons although total WM volume was lower in the group of dyslexics when age was partialled out. We presented an overview of uncorrected clusters of voxels (p  200) with reduced or increased GM volume. We found four significant correlations between factors of dyslexia representing various behavioural measures and the clusters found in the first analysis. In the whole sample, a factor related to performances in spelling correlated negatively with GM volume in the left posterior cerebellum. Within the group of dyslexics, a factor related to performances in Dutch-English rhyme words correlated positively with GM volume in the left and right caudate nucleus and negatively with increased total WM volume. Most of our findings were in accordance with previous reports. A relatively new finding was the involvement of the caudate nucleus. We confirmed the multiple cognitive nature of dyslexia and suggested that experience greatly influences anatomical alterations depending on various subtypes of dyslexia, especially in a student sample.

  12. Gray Matter Atrophy within the Default Mode Network of Fibromyalgia: A Meta-Analysis of Voxel-Based Morphometry Studies

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    Chemin Lin

    2016-01-01

    Full Text Available Over the years, studies have demonstrated morphological changes in the brain of fibromyalgia (FMS. We aimed to conduct a coordinate-based meta-analytic research through systemic review on voxel-based morphometry (VBM imaging results to identify consistent gray matter (GM difference between FMS patients and healthy subjects. We performed a comprehensive literature search in PubMed (January 2000–December 2015 and included six VBM publication on FMS. Stereotactic data were extracted from 180 patients of FMS and 123 healthy controls. By means of activation likelihood estimation (ALE technique, regional GM reduction in left medial prefrontal cortex and right dorsal posterior cingulate cortex was identified. Both regions are within the default mode network. In conclusion, the gray matter deficit is related to the both affective and nonaffective components of pain processing. This result also provided the neuroanatomical correlates for emotional and cognitive symptoms in FMS.

  13. Accuracy in the diagnosis of vertical root fractures, external root resorptions, and root perforations using cone-beam computed tomography with different voxel sizes of acquisition

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    Bragatto, Fernanda Paula; Iwaki Filho, Liogi; Kasuya, Amanda Vessoni Barbosa; Chicarelli, Mariliani; Queiroz, Alfredo Franco; Takeshita, Wilton Mitsunari; Iwaki, Lilian Cristina Vessoni

    2016-01-01

    Aim: The aim of this study is to assess the accuracy of images acquired with cone-beam computed tomography (CBCT) in the identification of three different root alterations. Materials and Methods: Forty human premolars were allocated to four experimental groups (n = 10): sound teeth (control), vertical root fracture (VRF), external root resorption (ERR), and root perforation (RP). After the root alterations had been produced, four teeth were randomly assembled into 10 macerated mandibles and submitted to CBCT. Images were acquired with five voxel sizes (0.125, 0.200, 0.250, 0.300, and 0.400 mm) and assessed by three experienced dental radiologists. Sensitivity, specificity, positive and negative predictive values, and the areas under the receiver operating characteristic curve (accuracy) were calculated. The accuracy of imaging in different voxel sizes was compared with Tukey exact binomial test (α=5%). Results: Accuracy with voxel sizes 0.125, 0.200, and 0.250 mm was significantly higher in the detection of ERRs and VRFs than voxel sizes 0.300 and 0.400 mm. No statistical difference was found in terms of accuracy among any of the studied voxel sizes in the identification of RPs. Conclusions: Voxel size 0.125 mm produced images with the best resolution without increasing radiation levels to the patient when compared to voxel sizes 0.200 and 0.250 mm. Voxel sizes 0.300 and 0.400 mm should be avoided in the identification of root alterations. PMID:27994322

  14. CNS involvement in primary Sjogren Syndrome: assessment of gray and white matter changes with MRI and voxel-based morphometry.

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    Tzarouchi, Loukia C; Tsifetaki, Niki; Konitsiotis, Spyridon; Zikou, Anastasia; Astrakas, Loukas; Drosos, Alexandros; Argyropoulou, Maria I

    2011-11-01

    The purpose of this study was to evaluate with MRI the involvement of gray matter and white matter structures in patients with primary Sjögren syndrome. Fifty-three patients with primary Sjögren syndrome, 18 age- and disease duration-matched patients with systemic sclerosis, and 35 age-matched control subjects were examined for differences in white matter hyperintensities (WMHIs) detected on FLAIR MR images. Differences in brain volume between patients with primary Sjögren syndrome and controls were studied by application of voxel-based morphometry to a 3D T1-weighted sequence. WMHIs were observed in 38 of the 53 patients with primary Sjögren syndrome, six of 18 patients with systemic sclerosis, and 17 of 35 controls. The numbers of WMHIs 2 mm or larger and the number smaller than 2 mm were higher in patients with primary Sjögren syndrome than in controls (≥ 2 mm, p = 0.004; syndrome patients and that in systemic sclerosis patients. After control for age, a positive relation was found between disease duration and total number of WMHIs (p = 0.037) and number of WMHIs 2 mm or larger (p = 0.023) in patients with primary Sjögren syndrome. In comparison with the controls, patients with primary Sjögren syndrome had decreased gray matter volume in the cortex, deep gray matter, and cerebellum. Associated loss of white matter volume was observed in areas corresponding to gray matter atrophy and in the corpus callosum (p syndrome have WMHIs and gray and white matter atrophy, probably related to cerebral vasculitis.

  15. The effect of in situ/in vitro three-dimensional quantitative computed tomography image voxel size on the finite element model of human vertebral cancellous bone.

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    Lu, Yongtao; Engelke, Klaus; Glueer, Claus-C; Morlock, Michael M; Huber, Gerd

    2014-11-01

    Quantitative computed tomography-based finite element modeling technique is a promising clinical tool for the prediction of bone strength. However, quantitative computed tomography-based finite element models were created from image datasets with different image voxel sizes. The aim of this study was to investigate whether there is an influence of image voxel size on the finite element models. In all 12 thoracolumbar vertebrae were scanned prior to autopsy (in situ) using two different quantitative computed tomography scan protocols, which resulted in image datasets with two different voxel sizes (0.29 × 0.29 × 1.3 mm(3) vs 0.18 × 0.18 × 0.6 mm(3)). Eight of them were scanned after autopsy (in vitro) and the datasets were reconstructed with two voxel sizes (0.32 × 0.32 × 0.6 mm(3) vs. 0.18 × 0.18 × 0.3 mm(3)). Finite element models with cuboid volume of interest extracted from the vertebral cancellous part were created and inhomogeneous bilinear bone properties were defined. Axial compression was simulated. No effect of voxel size was detected on the apparent bone mineral density for both the in situ and in vitro cases. However, the apparent modulus and yield strength showed significant differences in the two voxel size group pairs (in situ and in vitro). In conclusion, the image voxel size may have to be considered when the finite element voxel modeling technique is used in clinical applications.

  16. Small gray matter volume in orbitofrontal cortex in Prader-Willi syndrome: a voxel-based MRI study.

    Science.gov (United States)

    Ogura, Kaeko; Fujii, Toshikatsu; Abe, Nobuhito; Hosokai, Yoshiyuki; Shinohara, Mayumi; Takahashi, Shoki; Mori, Etsuro

    2011-07-01

    Prader-Willi syndrome (PWS) is a genetically determined neurodevelopmental disorder presenting with behavioral symptoms including hyperphagia, disinhibition, and compulsive behavior. The behavioral problems in individuals with PWS are strikingly similar to those in patients with frontal pathologies, particularly those affecting the orbitofrontal cortex (OFC). However, neuroanatomical abnormalities in the frontal lobe have not been established in PWS. The aim of this study was to look, using volumetric analysis, for morphological changes in the frontal lobe, especially the OFC, of the brains of individuals with PWS. Twelve adults with PWS and 13 age- and gender-matched control subjects participated in structural magnetic resonance imaging (MRI) scans. The whole-brain images were segmented and normalized to a standard stereotactic space. Regional gray matter volumes were compared between the PWS group and the control group using voxel-based morphometry. The PWS subjects showed small gray-matter volume in several regions, including the OFC, caudate nucleus, inferior temporal gyrus, precentral gyrus, supplementary motor area, postcentral gyrus, and cerebellum. The small gray-matter volume in the OFC remained significant in a separate analysis that included total gray matter volume as a covariate. These preliminary findings suggest that the neurobehavioral symptoms in individuals with PWS are related to structural brain abnormalities in these areas.

  17. Grey matter changes associated with deficit awareness in mild cognitive impairment: a voxel-based morphometry study.

    Science.gov (United States)

    Ford, Andrew H; Almeida, Osvaldo P; Flicker, Leon; Garrido, Griselda J; Greenop, Kathryn R; Foster, Jonathan K; Etherton-Beer, Christopher; van Bockxmeer, Frank M; Lautenschlager, Nicola T

    2014-01-01

    Reduced awareness of cognitive deficits in mild cognitive impairment (MCI) is associated with poorer outcomes although little is known about the anatomical correlates of this. We examined the association of insight and grey matter volume using a voxel-based morphometry approach in 65 volunteers with MCI and 55 healthy age-matched controls. Participants with MCI had multiple areas of subtle grey matter volume loss compared with controls, although these did not survive correction for multiple comparisons. These were predominantly in the temporal and anterior portions of the brain. Individuals with MCI did not differ from each other on a number of demographic and cognitive variables according to level of insight. Reduced awareness of cognitive deficits was associated with few differences in grey matter volume apart from a subtle loss of grey matter in the medial frontal gyri. Given the modest nature of these findings, the routine assessment of insight in non-clinical populations of individuals with MCI is therefore not supported. Prospective data in larger samples, however, would be helpful to clarify this further and determine if impaired insight predicts brain atrophy and cognitive decline.

  18. Whole-brain gray matter volume abnormalities in patients with generalized anxiety disorder: voxel-based morphometry.

    Science.gov (United States)

    Moon, Chung-Man; Kim, Gwang-Won; Jeong, Gwang-Woo

    2014-02-12

    Patients with generalized anxiety disorder (GAD) experience psychological distress because of excessive and uncontrollable anxiety in everyday life. Only a few morphological studies have so far focused on specific brain regions of interest as well as the gray matter volume changes in GAD patients. This study evaluated gray matter volume alterations in whole-brain areas between GAD patients and healthy controls, and sex differences between the specific brain areas with significant volume changes in GAD patients using voxel-based morphometry. Twenty-two patients with GAD (13 men and nine women), who were diagnosed using the DSM-IV-TR, and 22 age-matched healthy controls (13 men and nine women) participated in this study. The high-resolution MRI data were processed using voxel-based morphometry analysis on the basis of diffeomorphic anatomical registration through an exponentiated Lie algebra algorithm in Statistical Parametric Mapping 8. There was no significant difference in the total intracranial volume between GAD patients and controls, but a significant difference was observed between sexes (Psuperior temporal gyrus compared with the controls. As for the sex comparison, female patients showed a significant increase in the volume of the dorsolateral prefrontal cortex relative to male patients. Also, the volume of the dorsolateral prefrontal cortex in female patients was correlated positively with the Hamilton Anxiety Rating Scale score (γ=0.68, P=0.04). The specific morphological variations in patient with GAD will be helpful to understand the neural mechanism associated with a symptom of GAD. Furthermore, the findings would be valuable for the diagnostic accuracy of GAD using morphometric MRI analysis.

  19. A fourth gradient to overcome slice dependent phase effects of voxel-sized coils in planar arrays.

    Science.gov (United States)

    Bosshard, John C; Eigenbrodt, Edwin P; McDougall, Mary P; Wright, Steven M

    2010-01-01

    The signals from an array of densely spaced long and narrow receive coils for MRI are complicated when the voxel size is of comparable dimension to the coil size. The RF coil causes a phase gradient across each voxel, which is dependent on the distance from the coil, resulting in a slice dependent shift of k-space. A fourth gradient coil has been implemented and used with the system's gradient set to create a gradient field which varies with slice. The gradients are pulsed together to impart a slice dependent phase gradient to compensate for the slice dependent phase due to the RF coils. However the non-linearity in the fourth gradient which creates the desired slice dependency also results in a through-slice phase ramp, which disturbs normal slice refocusing and leads to additional signal cancelation and reduced field of view. This paper discusses the benefits and limitations of using a fourth gradient coil to compensate for the phase due to RF coils.

  20. A voxel-based morphometry study of regional gray and white matter correlate of self-disclosure.

    Science.gov (United States)

    Wang, ShanShan; Wei, DongTao; Li, WenFu; Li, HaiJiang; Wang, KangCheng; Xue, Song; Zhang, Qinglin; Qiu, Jiang

    2014-01-01

    Self-disclosure is an important performance in human social communication. Generally, an individual is likely to have a good physical and mental health if he is prone to self-disclosure under stressful life events. However, as for now, little is known about the neural structure associated with self-disclosure. Therefore, in this study, we used voxel-based morphometry to explore regional gray matter volume (rGMV) and white matter volume (rWMV) associated with self-disclosure measured by the Jourard Self-disclosure Questionnaire in a large sample of college students. Results showed that individual self-disclosure was significantly and positively associated with rGMV of the left postcentral gyrus, which might be related to strengthen individual's ability of body feeling; while self-disclosure was significantly and negatively associated with rGMV of the right orbitofrontal cortex (OFC), which might be involved in increased positive emotion experience seeking (intrinsically rewarding). In addition, individual self-disclosure was also associated with smaller rWMV in the right inferior parietal lobule (IPL). These findings suggested a biological basis for individual self-disclosure, distributed across different gray and white matter areas of the brain.

  1. Density abnormalities in normal-appearing gray matter in the middle-aged brain with white matter hyperintense lesions: a DARTEL-enhanced voxel-based morphometry study

    Directory of Open Access Journals (Sweden)

    Peng Y

    2016-05-01

    Full Text Available Yan Peng,1,* Shenhong Li,2,* Ying Zhuang,3,* Xiaojia Liu,4 Lin Wu,2 Honghan Gong,2 Dewu Liu,1 Fuqing Zhou2 1Burn Center, 2Department of Radiology, The First Affiliated Hospital, Nanchang University, 3Department of Oncology, The Second Hospital of Nanchang, Nanchang, Jiangxi Province, 4Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, People’s Republic of China *These authors contributed equally to this work Background and purpose: Little is known about the structural alterations within gray matter (GM in middle-aged subjects with white matter hyperintense (WMH lesions. Here, we aimed to examine the anatomical changes within the GM and their relationship to WMH lesion loads in middle-aged subjects. Participants and methods: Twenty-three middle-aged subjects with WMH lesions (WMH group and 23 demographically matched healthy control subjects participated in the study. A Diffeomorphic Anatomical Registration Through Exponentiated Liealgebra-enhanced voxel-based morphometry was used to measure the GM density, and the correlations between WMH lesion volume and extracted GM values in abnormal regions were identified by voxel-based morphometry analysis. Results: Compared with the healthy control subjects, the WMH group had a significantly decreased GM density in the left middle frontal gyrus, bilateral anterior cingulate cortex, left and right premotor cortex, and left and right middle cingulate cortex and an increased GM density in the bilateral cerebellum anterior lobe, left middle temporal gyrus, right temporoparietal junction, left and right prefrontal cortex (PFC, and left inferior parietal lobule. A relationship was observed between the normalized WMH lesion volume and the decreased GM density, including the left middle frontal gyrus (ρ=-0.629, P=0.002, bilateral anterior cingulate cortex (ρ=-0.507, P=0.019, right middle cingulate cortex (ρ=-0.484, P=0.026, and

  2. Larger mid-dorsolateral prefrontal gray matter volume in young binge drinkers revealed by voxel-based morphometry.

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    Sonia Doallo

    Full Text Available Binge drinking or heavy episodic drinking is a high prevalent pattern of alcohol consumption among young people in several countries. Despite increasing evidence that binge drinking is associated with impairments in executive aspects of working memory (i.e. self-ordered working memory, processes known to depend on the mid-dorsolateral prefrontal cortex (Brodmann areas 46 and 9, less is known about the impact of binge drinking on prefrontal gray matter integrity. Here, we investigated the effects of binge drinking on gray matter volume of mid- dorsolateral prefrontal cortex in youths. We used voxel-based morphometry on the structural magnetic resonance images of subjects reporting a persistent (at least three years binge drinking pattern of alcohol use (n = 11; age 22.43 ± 1.03 and control subjects (n = 21; age 22.18 ± 1.08 to measure differences in gray matter volume between both groups. In a region of interest analysis of the mid-dorsolateral prefrontal cortex, after co-varying for age and gender, we observed significantly larger gray matter volume in the left mid-dorsolateral prefrontal cortex (Brodmann areas 46 and 9 in binge drinkers in comparison with control subjects. Furthermore, there was a significant positive correlation between left mid-dorsolateral prefrontal cortex volume and Self-Ordered Pointing Test (SOPT total errors score in binge drinkers. The left mid-dorsolateral prefrontal cortex volume also correlated with the quantity and speed of alcohol intake. These findings indicate that a repeated exposure to alcohol -that does not meet criteria for alcohol dependence- throughout post-adolescent years and young adulthood is linked with structural anomalies in mid-dorsolateral prefrontal regions critically involved in executive aspects of working memory.

  3. From Cortical and Subcortical Grey Matter Abnormalities to Neurobehavioral Phenotype of Angelman Syndrome: A Voxel-Based Morphometry Study.

    Science.gov (United States)

    Aghakhanyan, Gayane; Bonanni, Paolo; Randazzo, Giovanna; Nappi, Sara; Tessarotto, Federica; De Martin, Lara; Frijia, Francesca; De Marchi, Daniele; De Masi, Francesco; Kuppers, Beate; Lombardo, Francesco; Caramella, Davide; Montanaro, Domenico

    2016-01-01

    Angelman syndrome (AS) is a rare neurogenetic disorder due to loss of expression of maternal ubiquitin-protein ligase E3A (UBE3A) gene. It is characterized by severe developmental delay, speech impairment, movement or balance disorder and typical behavioral uniqueness. Affected individuals show normal magnetic resonance imaging (MRI) findings, although mild dysmyelination may be observed. In this study, we adopted a quantitative MRI analysis with voxel-based morphometry (FSL-VBM) method to investigate disease-related changes in the cortical/subcortical grey matter (GM) structures. Since 2006 to 2013 twenty-six AS patients were assessed by our multidisciplinary team. From those, sixteen AS children with confirmed maternal 15q11-q13 deletions (mean age 7.7 ± 3.6 years) and twenty-one age-matched controls were recruited. The developmental delay and motor dysfunction were assessed using Bayley III and Gross Motor Function Measure (GMFM). Principal component analysis (PCA) was applied to the clinical and neuropsychological datasets. High-resolution T1-weighted images were acquired and FSL-VBM approach was applied to investigate differences in the local GM volume and to correlate clinical and neuropsychological changes in the regional distribution of GM. We found bilateral GM volume loss in AS compared to control children in the striatum, limbic structures, insular and orbitofrontal cortices. Voxel-wise correlation analysis with the principal components of the PCA output revealed a strong relationship with GM volume in the superior parietal lobule and precuneus on the left hemisphere. The anatomical distribution of cortical/subcortical GM changes plausibly related to several clinical features of the disease and may provide an important morphological underpinning for clinical and neurobehavioral symptoms in children with AS.

  4. Assessing age-related grey matter decline with Voxel-Based Morphometry depends significantly on segmentation and normalisation procedures

    Directory of Open Access Journals (Sweden)

    Dorothée V Callaert

    2014-06-01

    Full Text Available Healthy ageing coincides with a progressive decline of brain grey matter (GM ultimately affecting the entire brain. For a long time, manual delineation-based volumetry within predefined regions of interest (ROI has been the gold standard for assessing such degeneration. Voxel-Based Morphometry (VBM offers an automated alternative approach that, however, relies critically on the segmentation and spatial normalization of a large collection of images from different subjects. This can be achieved via different algorithms, with SPM5/SPM8, DARTEL of SPM8 and FSL tools (FAST, FNIRT being three of the most frequently used. We complemented these voxel based measurements with a ROI based approach, whereby the ROIs are defined by transforms of an atlas (containing different tissue probability maps as well as predefined anatomic labels to the individual subject images in order to obtain volumetric information at the level of the whole brain or within separate ROIs. Comparing GM decline between 21 young subjects (mean age 23 and 18 elderly (mean age 66 revealed that volumetric measurements differed significantly between methods. The unified segmentation/normalisation of SPM5/SPM8 revealed the largest age-related differences and DARTEL the smallest, with FSL being more similar to the DARTEL approach. Method specific differences were substantial after segmentation and most pronounced for the cortical structures in close vicinity to major sulci and fissures. Our findings suggest that algorithms that provide only limited degrees of freedom for local deformations (such as the unified segmentation and normalisation of SPM5/SPM8 tend to overestimate between-group differences in VBM results when compared to methods providing more flexible warping. This difference seems to be most pronounced if the anatomy of one of the groups deviates from custom templates, a finding that is of particular importance when results are compared across studies using different VBM

  5. Gray matter changes in right superior temporal gyrus in criminal psychopaths. Evidence from voxel-based morphometry.

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    Müller, Jürgen L; Gänssbauer, Susanne; Sommer, Monika; Döhnel, Katrin; Weber, Tatjana; Schmidt-Wilcke, Tobias; Hajak, Göran

    2008-08-30

    "Psychopathy" according to the PCL-R describes a specific subgroup of antisocial personality disorder with a high risk for criminal relapses. Lesion and imaging studies point towards frontal or temporal brain regions connected with disturbed social behavior, antisocial personality disorder (APD) and psychopathy. Morphologically, some studies described a reduced prefrontal brain volume, whereas others reported on temporal lobe atrophy. To further investigate whether participants with psychopathy according to the Psychopathy Checklist-Revised Version (PCL-R) show abnormalities in brain structure, we used voxel-based morphometry (VBM) to investigate region-specific changes in gray matter in 17 forensic male inpatients with high PCL-R scores (PCL-R>28) and 17 male control subjects with low PCL-R scores (PCLright superior temporal gyrus. This is the first study to show that psychopathy is associated with a decrease in gray matter in both frontal and temporal brain regions, in particular in the right superior temporal gyrus, supporting the hypothesis that a disturbed frontotemporal network is critically involved in the pathogenesis of psychopathy.

  6. Grey matter density decreases as well as increases in patients with classic galactosemia: A voxel-based morphometry study.

    Science.gov (United States)

    Timmers, Inge; van der Korput, Lisanne D; Jansma, Bernadette M; Rubio-Gozalbo, M Estela

    2016-10-01

    Brain impairments have been observed in patients with classic galactosemia, an inherited metabolic disorder resulting in a particular neuro-cognitive profile. Neuroimaging studies showed abnormalities such as diffuse white mater (WM) abnormalities and grey matter (GM) atrophy. Our current study analysed grey matter density using voxel-based morphometry (VBM) and compared the brains of eight adolescent patients with classic galactosemia with eight healthy gender- and aged-matched controls. GM density differences were found in several regions. Decreased GM density was found in the patients in the bilateral putamen and bilateral occipital cortex. Increased GM density in the patients, on the other hand, was found in the bilateral inferior frontal and medial prefrontal cortex. The anatomical profile of the abnormalities is in line with the neuro-cognitive profile of patients with classic galactosemia, including motor dysfunction, speech and language difficulties and higher order cognitive problems. Less favourable GM densities in patients (either increased or decreased compared to controls) correlated with younger age, a worse visual working memory performance, and an older age at initiation of the galactose-restricted diet. To conclude, this explorative study is the first to analyse the GM using VBM in this population, and demonstrates a mixed profile of both increased and decreased GM density in these patients.

  7. Subcortical and cortical gray matter differences between Kraepelinian and non-Kraepelinian schizophrenia patients identified using voxel-based morphometry.

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    Molina, Vicente; Hernández, Juan A; Sanz, Javier; Paniagua, Juan C; Hernández, Ana I; Martín, Carmen; Matías, Juan; Calama, Julia; Bote, Berta

    2010-10-30

    The long-term outcome of schizophrenia patients may differ depending on their brain structure. This would be reflected in significant structural differences between poor-outcome (i.e., Kraepelinian) and non-Kraepelinian patients. To assess this possibility, we have evaluated the degree of deviation in brain structure in Kraepelinian patients with respect to controls and non-Kraepelinian schizophrenia patients. We used voxel-brain morphometry (VBM) to assess the differences in gray matter volume across the brain in the Kraepelinian group with respect to the healthy controls and non-Kraepelinian patients. Twenty-six Kraepelinian and 18 non-Kraepelinian schizophrenia patients and 41 healthy controls were included. With respect to the healthy controls, the Kraepelinian patients showed a very significant decrease in gray matter in the frontal, occipital, and limbic cortices, and, at a subcortical level, bilaterally in the striatum and thalamus. In comparison with the non-Kraepelinian patients, the Kraepelinian individuals continued to show a similar subcortical decrease. Thus, Kraepelinian patients may be characterized by a distinct pattern of brain abnormalities, in particular, in subcortical regions.

  8. Voxel-based morphometry in opera singers: Increased gray-matter volume in right somatosensory and auditory cortices.

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    Kleber, Boris; Veit, Ralf; Moll, Christina Valérie; Gaser, Christian; Birbaumer, Niels; Lotze, Martin

    2016-06-01

    In contrast to instrumental musicians, professional singers do not train on a specific instrument but perfect a motor system that has already been extensively trained during speech motor development. Previous functional imaging studies suggest that experience with singing is associated with enhanced somatosensory-based vocal motor control. However, experience-dependent structural plasticity in vocal musicians has rarely been studied. We investigated voxel-based morphometry (VBM) in 27 professional classical singers and compared gray matter volume in regions of the "singing-network" to an age-matched group of 28 healthy volunteers with no special singing experience. We found right hemispheric volume increases in professional singers in ventral primary somatosensory cortex (larynx S1) and adjacent rostral supramarginal gyrus (BA40), as well as in secondary somatosensory (S2) and primary auditory cortices (A1). Moreover, we found that earlier commencement with vocal training correlated with increased gray-matter volume in S1. However, in contrast to studies with instrumental musicians, this correlation only emerged in singers who began their formal training after the age of 14years, when speech motor development has reached its first plateau. Structural data thus confirm and extend previous functional reports suggesting a pivotal role of somatosensation in vocal motor control with increased experience in singing. Results furthermore indicate a sensitive period for developing additional vocal skills after speech motor coordination has matured.

  9. Association between regional white and gray matter volume and ambiguity tolerance: Evidence from voxel-based morphometry.

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    Tong, Dandan; Yang, Wenjing; Zhang, Qinglin; Li, Wenfu; Wei, Dongtao; Che, Xianwei; Zhang, Meng; Hitchman, Glenn; Qiu, Jiang; Liu, Yijun; Cao, Guikang

    2015-08-01

    The concept of tolerance of ambiguity (AT) is defined as the way in which an individual tends to perceive and deal with confusing, vague, and unclear situations. AT is generally considered as an important personality trait, but the neural mechanisms underlying individual differences in AT have never been investigated. Using voxel-based morphometry and MSTAT-II scale, we investigated the correlations between AT and regional white matter volume (rWMV) and regional gray matter volume (rGMV) in 351 young healthy subjects. We found AT to be positively correlated with rGMV in the dorsolateral prefrontal cortex (DLPFC), and negatively correlated with rGMV in the precuneus. These results indicate that increased rGMV in the left DLPFC may lead to characteristics of ambiguous stimuli consideration from multiple contexts and risk taking. Decreased rGMV in the left precuneus may be associated with a high tolerance for ambiguity, which attributes uncertainty to self-related factors.

  10. Visceral sensitivity correlates with decreased regional gray matter volume in healthy volunteers: a voxel-based morphometry study.

    Science.gov (United States)

    Elsenbruch, Sigrid; Schmid, Julia; Kullmann, Jennifer S; Kattoor, Joswin; Theysohn, Nina; Forsting, Michael; Kotsis, Vassilios

    2014-02-01

    Regional changes in brain structure have been reported in patients with altered visceral sensitivity and chronic abdominal pain, such as in irritable bowel syndrome. It remains unknown whether structural brain changes are associated with visceral sensitivity. Therefore, we present the first study in healthy individuals to address whether interindividual variations in gray matter volume (GMV) in pain-relevant regions correlate with visceral sensitivity. In 92 healthy young adults (52 female), we assessed rectal sensory and pain thresholds and performed voxel-based morphometry (VBM) to compute linear regression models with visceral sensory and pain thresholds, respectively, as independent variable and GMV in a priori-defined regions of interest (ROIs) as dependent variable. All results were familywise error (FWE) corrected at a level of PFWEpain, without evidence of sex differences. Lower rectal sensory threshold (ie, increased sensitivity) correlated significantly with reduced GMV in the thalamus, insula, posterior cingulate cortex, ventrolateral and orbitofrontal prefrontal cortices, amygdala, and basal ganglia (all PFWEpain threshold was associated with reduced GMV in the right thalamus (PFWE=.051). These are the first data supporting that increased visceral sensitivity correlates with decreased gray matter volume in pain-relevant brain regions. These findings support that alterations in brain morphology not only occur in clinical pain conditions but also occur according to normal interindividual variations in visceral sensitivity. Copyright © 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  11. Radiation-induced changes in normal-appearing gray matter in patients with nasopharyngeal carcinoma: a magnetic resonance imaging voxel-based morphometry study

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Xiao-Fei; Zheng, Xiao-Li; Zhang, Wei-Dong; Liu, Li-Zhi; Zhang, You-Ming [State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou (China); Sun Yat-sen University Cancer Center, Department of Medical Imaging and Interventional Radiology, Guangzhou (China); Chen, Ming-Yuan [Sun Yat-sen University Cancer Center, Department of Nasopharyngeal Carcinoma, Guangzhou (China); Li, Li [Sun Yat-sen University Cancer Center, Department of Medical Imaging and Interventional Radiology, Guangzhou (China)

    2014-05-15

    Evidence is accumulating that temporal lobe radiation necrosis in patients with nasopharyngeal carcinoma (NPC) after radiotherapy (RT) could involve gray matter (GM). The purpose of the study was to assess the radiation-induced GM volume differences between NPC patients who had and had not received RT and the effect of time after RT on GM volume differences in those patients who had received RT. We used magnetic resonance imaging voxel-based morphometry (VBM) to assess differences in GM volume between 30 NPC patients with normal-appearing whole-brain GM after RT and 15 control patients with newly diagnosed but not yet medically treated NPC. Correlation analyses were used to investigate the relationship between GM volume changes and time after RT. Patients who had received RT had GM volume decreases in the bilateral superior temporal gyrus, left middle temporal gyrus, right fusiform gyrus, right precentral gyrus, and right inferior parietal lobule (p < 0.001, uncorrected, cluster size >100 voxels). Moreover, the correlation analysis indicated that regional GM volume loss in the left superior temporal gyrus, left middle temporal gyrus, and right fusiform gyrus were negatively related to the mean dose to the ipsilateral temporal lobe, respectively. These results indicate that GM volume deficits in bilateral temporal lobes in patients who had received RT might be radiation-induced. Our findings might provide new insight into the pathogenesis of radiation-induced structural damage in normal-appearing brain tissue. Yet this is an exploratory study, whose findings should therefore be taken with caution. (orig.)

  12. The effect of voxel size on dose distribution in Varian Clinac iX 6 MV photon beam using Monte Carlo simulation

    Science.gov (United States)

    Yani, Sitti; Dirgayussa, I. Gde E.; Rhani, Moh. Fadhillah; Haryanto, Freddy; Arif, Idam

    2015-09-01

    Recently, Monte Carlo (MC) calculation method has reported as the most accurate method of predicting dose distributions in radiotherapy. The MC code system (especially DOSXYZnrc) has been used to investigate the different voxel (volume elements) sizes effect on the accuracy of dose distributions. To investigate this effect on dosimetry parameters, calculations were made with three different voxel sizes. The effects were investigated with dose distribution calculations for seven voxel sizes: 1 × 1 × 0.1 cm3, 1 × 1 × 0.5 cm3, and 1 × 1 × 0.8 cm3. The 1 × 109 histories were simulated in order to get statistical uncertainties of 2%. This simulation takes about 9-10 hours to complete. Measurements are made with field sizes 10 × 10 cm2 for the 6 MV photon beams with Gaussian intensity distribution FWHM 0.1 cm and SSD 100.1 cm. MC simulated and measured dose distributions in a water phantom. The output of this simulation i.e. the percent depth dose and dose profile in dmax from the three sets of calculations are presented and comparisons are made with the experiment data from TTSH (Tan Tock Seng Hospital, Singapore) in 0-5 cm depth. Dose that scored in voxels is a volume averaged estimate of the dose at the center of a voxel. The results in this study show that the difference between Monte Carlo simulation and experiment data depend on the voxel size both for percent depth dose (PDD) and profile dose. PDD scan on Z axis (depth) of water phantom, the big difference obtain in the voxel size 1 × 1 × 0.8 cm3 about 17%. In this study, the profile dose focused on high gradient dose area. Profile dose scan on Y axis and the big difference get in the voxel size 1 × 1 × 0.1 cm3 about 12%. This study demonstrated that the arrange voxel in Monte Carlo simulation becomes important.

  13. The effect of voxel size on dose distribution in Varian Clinac iX 6 MV photon beam using Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yani, Sitti, E-mail: sitti.yani@s.itb.ac.id [Nuclear Physics and Biophysics Division, Physics Department, Institut Teknologi Bandung (Indonesia); Akademi Kebidanan Pelita Ibu, Kendari (Indonesia); Dirgayussa, I Gde E.; Haryanto, Freddy; Arif, Idam [Nuclear Physics and Biophysics Division, Physics Department, Institut Teknologi Bandung (Indonesia); Rhani, Moh. Fadhillah [Tan Tock Seng Hospital (Singapore)

    2015-09-30

    Recently, Monte Carlo (MC) calculation method has reported as the most accurate method of predicting dose distributions in radiotherapy. The MC code system (especially DOSXYZnrc) has been used to investigate the different voxel (volume elements) sizes effect on the accuracy of dose distributions. To investigate this effect on dosimetry parameters, calculations were made with three different voxel sizes. The effects were investigated with dose distribution calculations for seven voxel sizes: 1 × 1 × 0.1 cm{sup 3}, 1 × 1 × 0.5 cm{sup 3}, and 1 × 1 × 0.8 cm{sup 3}. The 1 × 10{sup 9} histories were simulated in order to get statistical uncertainties of 2%. This simulation takes about 9-10 hours to complete. Measurements are made with field sizes 10 × 10 cm2 for the 6 MV photon beams with Gaussian intensity distribution FWHM 0.1 cm and SSD 100.1 cm. MC simulated and measured dose distributions in a water phantom. The output of this simulation i.e. the percent depth dose and dose profile in d{sub max} from the three sets of calculations are presented and comparisons are made with the experiment data from TTSH (Tan Tock Seng Hospital, Singapore) in 0-5 cm depth. Dose that scored in voxels is a volume averaged estimate of the dose at the center of a voxel. The results in this study show that the difference between Monte Carlo simulation and experiment data depend on the voxel size both for percent depth dose (PDD) and profile dose. PDD scan on Z axis (depth) of water phantom, the big difference obtain in the voxel size 1 × 1 × 0.8 cm{sup 3} about 17%. In this study, the profile dose focused on high gradient dose area. Profile dose scan on Y axis and the big difference get in the voxel size 1 × 1 × 0.1 cm{sup 3} about 12%. This study demonstrated that the arrange voxel in Monte Carlo simulation becomes important.

  14. Marine reserves: size and age do matter.

    Science.gov (United States)

    Claudet, Joachim; Osenberg, Craig W; Benedetti-Cecchi, Lisandro; Domenici, Paolo; García-Charton, José-Antonio; Pérez-Ruzafa, Angel; Badalamenti, Fabio; Bayle-Sempere, Just; Brito, Alberto; Bulleri, Fabio; Culioli, Jean-Michel; Dimech, Mark; Falcón, Jesús M; Guala, Ivan; Milazzo, Marco; Sánchez-Meca, Julio; Somerfield, Paul J; Stobart, Ben; Vandeperre, Frédéric; Valle, Carlos; Planes, Serge

    2008-05-01

    Marine reserves are widely used throughout the world to prevent overfishing and conserve biodiversity, but uncertainties remain about their optimal design. The effects of marine reserves are heterogeneous. Despite theoretical findings, empirical studies have previously found no effect of size on the effectiveness of marine reserves in protecting commercial fish stocks. Using 58 datasets from 19 European marine reserves, we show that reserve size and age do matter: Increasing the size of the no-take zone increases the density of commercial fishes within the reserve compared with outside; whereas the size of the buffer zone has the opposite effect. Moreover, positive effects of marine reserve on commercial fish species and species richness are linked to the time elapsed since the establishment of the protection scheme. The reserve size-dependency of the response to protection has strong implications for the spatial management of coastal areas because marine reserves are used for spatial zoning.

  15. Age-related cortical grey matter reductions in non-demented Down's syndrome adults determined by MRI with voxel-based morphometry.

    Science.gov (United States)

    Teipel, Stefan J; Alexander, Gene E; Schapiro, Marc B; Möller, Hans-Jürgen; Rapoport, Stanley I; Hampel, Harald

    2004-04-01

    Ageing in Down's syndrome is accompanied by amyloid and neurofibrillary pathology the distribution of which replicates pathological features of Alzheimer's disease. With advancing age, an increasing proportion of Down's syndrome subjects >40 years old develop progressive cognitive impairment, resembling the cognitive profile of Alzheimer's disease. Based on these findings, Down's syndrome has been proposed as a model to study the predementia stages of Alzheimer's disease. Using an interactive anatomical segmentation technique and volume-of-interest measurements of MRI, we showed recently that non-demented Down's syndrome adults had significantly reduced hippocampus, entorhinal cortex and corpus callosum sizes with increasing age. In this study, we applied the automated and objective technique of voxel-based morphometry, implemented in SPM99, to the analysis of structural MRI from 27 non-demented Down's syndrome adults (mean age 41.1 years, 15 female). Regional grey matter volume was decreased with advancing age in bilateral parietal cortex (mainly the precuneus and inferior parietal lobule), bilateral frontal cortex with left side predominance (mainly middle frontal gyrus), left occipital cortex (mainly lingual cortex), right precentral and left postcentral gyrus, left transverse temporal gyrus, and right parahippocampal gyrus. The reductions were unrelated to gender, intracranial volume or general cognitive function. Grey matter volume was relatively preserved in subcortical nuclei, periventricular regions, the basal surface of the brain (bilateral orbitofrontal and anterior temporal) and the anterior cingulate gyrus. Our findings suggest grey matter reductions in allocortex and association neocortex in the predementia stage of Down's syndrome. The most likely substrate of these changes is alterations or loss of allocortical and neocortical neurons due to Alzheimer's disease-type pathology.

  16. Relationship between personality and gray matter volume in healthy young adults: a voxel-based morphometric study.

    Science.gov (United States)

    Lu, Fengmei; Huo, Yajun; Li, Meiling; Chen, Heng; Liu, Feng; Wang, Yifeng; Long, Zhiliang; Duan, Xujun; Zhang, Jiang; Zeng, Ling; Chen, Huafu

    2014-01-01

    This study aims to investigate the neurostructural foundations of the human personality in young adults. High-resolution structural T1-weighted MR images of 71 healthy young individuals were processed using voxel-based morphometric (VBM) approach. Multiple regression analyses were performed to identify the associations between personality traits and gray matter volume (GMV). The Eysenck Personality Questionnaire-Revised, Short Scale for Chinese was chosen to assess the personality traits. This scale includes four dimensions, namely, extraversion, neuroticism, psychoticism, and lie. Particularly, we studied on two dimensions (extraversion and neuroticism) of Eysenck's personality. Our results showed that extraversion was negatively correlated with GMV of the bilateral amygdala, the bilateral parahippocampal gyrus, the right middle temporal gyrus, and the left superior frontal gyrus, all of which are involved in emotional and social cognitive processes. These results might suggest an association between extraversion and affective processing. In addition, a positive correlation was detected between neuroticism and GMV of the right cerebellum, a key brain region for negative affect coordination. Meanwhile, a negative association was revealed between GMV of the left superior frontal gyrus and neuroticism. These results may prove that neuroticism is related to several brain regions involved in regulating negative emotions. Based on those findings, we concluded that brain regions involved in social cognition and affective process accounted for modulation and shaping of personality traits among young individuals. Results of this study may serve as a basis for elucidating the anatomical factors of personality.

  17. A voxel-based morphometry study of gray matter correlates of facial emotion recognition in bipolar disorder.

    Science.gov (United States)

    Neves, Maila de Castro L; Albuquerque, Maicon Rodrigues; Malloy-Diniz, Leandro; Nicolato, Rodrigo; Silva Neves, Fernando; de Souza-Duran, Fábio Luis; Busatto, Geraldo; Corrêa, Humberto

    2015-08-30

    Facial emotion recognition (FER) is one of the many cognitive deficits reported in bipolar disorder (BD) patients. The aim of this study was to investigate neuroanatomical correlates of FER impairments in BD type I (BD-I). Participants comprised 21 euthymic BD-I patients without Axis I DSM IV-TR comorbidities and 21 healthy controls who were assessed using magnetic resonance imaging and the Penn Emotion Recognition Test (ER40). Preprocessing of images used DARTEL (diffeomorphic anatomical registration through exponentiated Lie algebra) for optimized voxel-based morphometry in SPM8. Compared with healthy subjects, BD-I patients performed poorly in on the ER40 and had reduced gray matter volume (GMV) in the left orbitofrontal cortex, superior portion of the temporal pole and insula. In the BD-I group, the statistical maps indicated a direct correlation between FER on the ER40 and right middle cingulate gyrus GMV. Our findings are consistent with the previous studies regarding the overlap of multiple brain networks of social cognition and BD neurobiology, particularly components of the anterior-limbic neural network. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  18. Cerebral gray matter volume variation in female-to-male transsexuals: a voxel-based morphometric study.

    Science.gov (United States)

    Kim, Tae-Hoon; Kim, Seok-Kwun; Jeong, Gwang-Woo

    2015-12-16

    Several studies seem to support the hypothesis that brain anatomy is associated with transsexualism. However, these studies were still limited because few neuroanatomical findings have been obtained from female-to-male (FtM) transsexuals. This study compared the cerebral regional volumes of gray matter (GM) between FtM transsexuals and female controls using a voxel-based morphometry. Twelve FtM transsexuals who had undergone sex-reassignment surgery and 15 female controls participated in this study. Both groups were age matched and right-handed, with no history of neurological illness. Fifteen female controls were recruited to determine whether GM volumes in FtM transsexuals more closely resembled individuals who shared their biological sex. MRI data were processed using SPM 8 with the diffeomorphic anatomical registration through exponentiated Lie algebra (DARTEL). FtM transsexuals showed significantly larger volumes of the thalamus, hypothalamus, midbrain, gyrus rectus, head of caudate nucleus, precentral gyrus, and subcallosal area compared with the female controls. However, the female controls showed a significantly larger volume in the superior temporal gyrus including Heschl's gyrus and Rolandic operculum. These findings confirm that the volume difference in brain substructures in FtM transsexuals is likely to be associated with transsexualism and that transsexualism is probably associated with distinct cerebral structures, determining gender identity.

  19. Relationship between personality and gray matter volume in healthy young adults: a voxel-based morphometric study.

    Directory of Open Access Journals (Sweden)

    Fengmei Lu

    Full Text Available This study aims to investigate the neurostructural foundations of the human personality in young adults. High-resolution structural T1-weighted MR images of 71 healthy young individuals were processed using voxel-based morphometric (VBM approach. Multiple regression analyses were performed to identify the associations between personality traits and gray matter volume (GMV. The Eysenck Personality Questionnaire-Revised, Short Scale for Chinese was chosen to assess the personality traits. This scale includes four dimensions, namely, extraversion, neuroticism, psychoticism, and lie. Particularly, we studied on two dimensions (extraversion and neuroticism of Eysenck's personality. Our results showed that extraversion was negatively correlated with GMV of the bilateral amygdala, the bilateral parahippocampal gyrus, the right middle temporal gyrus, and the left superior frontal gyrus, all of which are involved in emotional and social cognitive processes. These results might suggest an association between extraversion and affective processing. In addition, a positive correlation was detected between neuroticism and GMV of the right cerebellum, a key brain region for negative affect coordination. Meanwhile, a negative association was revealed between GMV of the left superior frontal gyrus and neuroticism. These results may prove that neuroticism is related to several brain regions involved in regulating negative emotions. Based on those findings, we concluded that brain regions involved in social cognition and affective process accounted for modulation and shaping of personality traits among young individuals. Results of this study may serve as a basis for elucidating the anatomical factors of personality.

  20. Late-life obesity is associated with smaller global and regional gray matter volumes: a voxel-based morphometric study.

    Science.gov (United States)

    Brooks, S J; Benedict, C; Burgos, J; Kempton, M J; Kullberg, J; Nordenskjöld, R; Kilander, L; Nylander, R; Larsson, E-M; Johansson, L; Ahlström, H; Lind, L; Schiöth, H B

    2013-02-01

    Obesity adversely affects frontal lobe brain structure and function. Here we sought to show that people who are obese versus those who are of normal weight over a 5-year period have differential global and regional brain volumes. Using voxel-based morphometry, contrasts were done between those who were recorded as being either obese or of normal weight over two time points in the 5 years prior to the brain scan. In a post-hoc preliminary analysis, we compared scores for obese and normal weight people who completed the trail-making task. A total of 292 subjects were examined following exclusions (for example, owing to dementia, stroke and cortical infarcts) from the Prospective Investigation of the Vasculature in Uppsala Seniors cohort with a body mass index of normal weight (obese (30 kg m(-2)). People who were obese had significantly smaller total brain volumes and specifically, significantly reduced total gray matter (GM) volume (GMV) (with no difference in white matter or cerebrospinal fluid). Initial exploratory whole brain uncorrected analysis revealed that people who were obese had significantly smaller GMV in the bilateral supplementary motor area, bilateral dorsolateral prefrontal cortex (DLPFC), left inferior frontal gyrus and left postcentral gyrus. Secondary more stringent corrected analyses revealed a surviving cluster of GMV difference in the left DLPFC. Finally, post-hoc contrasts of scores on the trail-making task, which is linked to DLPFC function, revealed that obese people were significantly slower than those of normal weight. These findings suggest that in comparison with normal weight, people who are obese have smaller GMV, particularly in the left DLPFC. Our results may provide evidence for a potential working memory mechanism for the cognitive suppression of appetite that may lower the risk of developing obesity in later life.

  1. The gray matter volume of the amygdala is correlated with the perception of melodic intervals: a voxel-based morphometry study.

    Science.gov (United States)

    Li, Xueting; De Beuckelaer, Alain; Guo, Jiahui; Ma, Feilong; Xu, Miao; Liu, Jia

    2014-01-01

    Music is not simply a series of organized pitches, rhythms, and timbres, it is capable of evoking emotions. In the present study, voxel-based morphometry (VBM) was employed to explore the neural basis that may link music to emotion. To do this, we identified the neuroanatomical correlates of the ability to extract pitch interval size in a music segment (i.e., interval perception) in a large population of healthy young adults (N = 264). Behaviorally, we found that interval perception was correlated with daily emotional experiences, indicating the intrinsic link between music and emotion. Neurally, and as expected, we found that interval perception was positively correlated with the gray matter volume (GMV) of the bilateral temporal cortex. More important, a larger GMV of the bilateral amygdala was associated with better interval perception, suggesting that the amygdala, which is the neural substrate of emotional processing, is also involved in music processing. In sum, our study provides one of first neuroanatomical evidence on the association between the amygdala and music, which contributes to our understanding of exactly how music evokes emotional responses.

  2. The gray matter volume of the amygdala is correlated with the perception of melodic intervals: a voxel-based morphometry study.

    Directory of Open Access Journals (Sweden)

    Xueting Li

    Full Text Available Music is not simply a series of organized pitches, rhythms, and timbres, it is capable of evoking emotions. In the present study, voxel-based morphometry (VBM was employed to explore the neural basis that may link music to emotion. To do this, we identified the neuroanatomical correlates of the ability to extract pitch interval size in a music segment (i.e., interval perception in a large population of healthy young adults (N = 264. Behaviorally, we found that interval perception was correlated with daily emotional experiences, indicating the intrinsic link between music and emotion. Neurally, and as expected, we found that interval perception was positively correlated with the gray matter volume (GMV of the bilateral temporal cortex. More important, a larger GMV of the bilateral amygdala was associated with better interval perception, suggesting that the amygdala, which is the neural substrate of emotional processing, is also involved in music processing. In sum, our study provides one of first neuroanatomical evidence on the association between the amygdala and music, which contributes to our understanding of exactly how music evokes emotional responses.

  3. Comparison of grey matter and metabolic reductions in frontotemporal dementia using FDG-PET and voxel-based morphometric MR studies

    Energy Technology Data Exchange (ETDEWEB)

    Kanda, Tomonori; Uemura, Takafumi; Miyamoto, Naokazu; Yoshikawa, Toshiki; Kono, Atsushi K. [Hyogo Brain and Heart Center, Department of Radiology and Nuclear Medicine, Himeji, Hyogo (Japan); Ishii, Kazunari [Hyogo Brain and Heart Center, Department of Radiology and Nuclear Medicine, Himeji, Hyogo (Japan); Hyogo Institute for Aging Brain and Cognitive Disorders, Division of Neuroimaging Research, Himeji, Hyogo (Japan); Mori, Etsuro [Hyogo Institute for Aging Brain and Cognitive Disorders, Division of Clinical Neurosciences, Himeji, Hyogo (Japan); Tohoku University Graduate School of Medicine, Behavioral Neurology and Cognitive Neuroscience, Sendai, Miyagi (Japan)

    2008-12-15

    The aim of this study was to investigate the regional differences between the morphologic and functional changes in the same patients with frontotemporal dementia (FTD) using statistical parametric mapping and voxel-based morphometry (VBM). Thirteen FTD patients (mean age, 64.9 years old; mean MMSE score, 17.7), 20 sex-matched Alzheimer's disease (AD) patients (mean age, 65.0 years old; mean MMSE score, 17.5), and 20 normal volunteers (mean age, 65.2 years old; mean MMSE score, 29.0) underwent both [{sup 18}F]FDG positron emission tomography and three-dimensional spoiled gradient echo MRI. Statistical parametric mapping was used to conduct a VBM analysis of the morphologic data, which were compared voxel by voxel with the results of a similar analysis of glucose metabolic data. FTD patients showed decreased grey matter volume and decreased glucose metabolism in the frontal lobe and anterior temporal lobe. In addition, there was a clear asymmetry in grey matter volume in FTD patients by the VBM analysis while the glucose metabolic data showed little asymmetry. In AD patients, glucose metabolic reduction occurred in the bilateral posterior cingulate gyri and parietal lobules while grey matter density decreased the least in the same patients. In FTD, metabolic and morphologic changes occur in the bilateral frontal lobe and temporal lobe with a limited asymmetry whereas there was considerable discordance in the AD group. (orig.)

  4. Diagnostic Accuracy of CBCT with Different Voxel Sizes and Intraoral Digital Radiography for Detection of Periapical Bone Lesions: An Ex-Vivo Study

    Directory of Open Access Journals (Sweden)

    Shirin Sakhdari

    2016-10-01

    Full Text Available Objectives: This study sought to assess the diagnostic accuracy of cone beam computed tomography (CBCT with different voxel sizes and intraoral digital radiography with photostimulable phosphor (PSP plate for detection of periapical (PA bone lesions.Materials and Methods: In this ex vivo diagnostic study, one-millimeter defects were created in the alveolar sockets of 15 bone blocks, each with two posterior teeth. A no-defect control group was also included. Digital PA radiographs with PSP plates and CBCT scans with 200, 250 and 300μ voxel sizes were obtained. Four observers evaluated the possibility of lesion detection using a 5-point scale. Sensitivity, specificity, positive predictive value (PPV and negative predicative value (NPV were analyzed using one-way ANOVA and Tamhane’s post hoc test. Kappa and weighted kappa statistics were applied to assess intraobserver and interobserver agreements.Results: Cochrane Q test showed no significant difference between PSP and CBCT imaging modalities in terms of kappa and weighted kappa statistics (P=0.675. The complete sensitivity and complete NPV for 200 and 250 μ voxel sizes were higher than those of 300 μ voxel size and digital radiography (P<0.001. No significant difference was noted in other parameters among other imaging modalities (P=0.403.Conclusions: The results showed that high-resolution CBCT scans had higher diagnostic accuracy than PSP digital radiography for detection of artificially created PA bone lesions. Voxel size (field of view must be taken into account to minimize patient radiation dose.Keywords: Diagnosis; Cone-Beam Computed Tomography; Radiography, Dental, Digital; Periapical Periodontitis

  5. Skeletal dosimetry for external exposures to photons based on {mu}CT images of spongiosa: Consideration of voxel resolution, cluster size, and medullary bone surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, R.; Khoury, H. J.; Vieira, J. W.; Brown, K. A. Robson [Departamento de Energia Nuclear, Universidade Federal de Pernambuco, Avenida Professor Luiz Freire 1000, Cidade Universitaria, CEP 50740-540, Recife, Pernambuco (Brazil); Centro Federal de Educacao Tecnologica de Pernambuco, Avenida Professor Luiz Freire 500, CEP 50740-540, Recife, Pernambuco, Brazil and Escola Politecnica, UPE, Rua Benfica 455, CEP 50751-460, Recife, Pernambuco (Brazil); Imaging Laboratory, Department of Archaeology and Anthropology, University of Bristol, 43 Woodland Road, Bristol BS8 1UU (United Kingdom)

    2009-11-15

    Skeletal dosimetry based on {mu}CT images of trabecular bone has recently been introduced to calculate the red bone marrow (RBM) and the bone surface cell (BSC) equivalent doses in human phantoms for external exposure to photons. In order to use the {mu}CT images for skeletal dosimetry, spongiosa voxels in the skeletons were replaced at run time by so-called micromatrices, which have exactly the size of a spongiosa voxel and contain segmented trabecular bone and marrow microvoxels. A cluster (=parallelepiped) of 2x2x2=8 micromatrices was used systematically and periodically throughout the spongiosa volume during the radiation transport calculation. Systematic means that when a particle leaves a spongiosa voxel to enter into a neighboring spongiosa voxel, then the next micromatrix in the cluster will be used. Periodical means that if the particle travels through more than two spongiosa voxels in a row, then the cluster will be repeated. Based on the bone samples available at the time, clusters of up to 3x3x3=27 micromatrices were studied. While for a given trabecular bone volume fraction the whole-body RBM equivalent dose showed converging results for cluster sizes between 8 and 27 micromatrices, this was not the case for the BSC equivalent dose. The BSC equivalent dose seemed to be very sensitive to the number, form, and thickness of the trabeculae. In addition, the cluster size and/or the microvoxel resolution were considered to be possible causes for the differences observed. In order to resolve this problem, this study used a bone sample large enough to extract clusters containing up to 8x8x8=512 micromatrices and which was scanned with two different voxel resolutions. Taking into account a recent proposal, this investigation also calculated the BSC equivalent dose on medullary surfaces of cortical bone in the arm and leg bones. The results showed (1) that different voxel resolutions have no effect on the RBM equivalent dose but do influence the BSC equivalent

  6. Detecting damaged regions of cerebral white matter in the subacute phase after carbon monoxide poisoning using voxel-based analysis with diffusion tensor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Shunrou; Nishimoto, Hideaki; Ogasawara, Kuniaki [Iwate Medical University, Department of Neurosurgery, Morioka (Japan); Beppu, Takaaki [Iwate Medical University, Department of Neurosurgery, Morioka (Japan); Iwate Medical University, Department of Hyperbaric Medicine, Morioka (Japan); Sanjo, Katsumi; Koeda, Atsuhiko [Iwate Medical University, Department of Psychiatry, Morioka (Japan); Mori, Kiyoshi [Iwate Prefectural Critical Care and Emergency Center, Department of Neurology, Morioka (Japan); Kudo, Kohsuke; Sasaki, Makoto [Iwate Medical University, Advanced Medical Research Center, Morioka (Japan)

    2012-07-15

    The present study aimed to detect the main regions of cerebral white matter (CWM) showing damage in the subacute phase for CO-poisoned patients with chronic neurological symptoms using voxel-based analysis (VBA) with diffusion tensor imaging (DTI). Subjects comprised 22 adult CO-poisoned patients and 16 age-matched healthy volunteers as controls. Patients were classified into patients with transient acute symptoms only (group A) and patients with chronic neurological symptoms (group S). In all patients, DTI covering the whole brain was performed with a 3.0-T magnetic resonance imaging system at 2 weeks after CO exposure. As procedures for VBA, all fractional anisotropy (FA) maps obtained from DTI were spatially normalized, and FA values for all voxels in the whole CWM on normalized FA maps were statistically compared among the two patient groups and controls. Voxels with significant differences in FA were detected at various regions in comparisons between groups S and A and between group S and controls. In these comparisons, more voxels were detected in deep CWM, including the centrum semiovale, than in other regions. A few voxels were detected between group A and controls. Absolute FA values in the centrum semiovale were significantly lower in group S than in group A or controls. VBA demonstrated that CO-poisoned patients with chronic neurological symptoms had already suffered damage to various CWM regions in the subacute phase. In these regions, the centrum semiovale was suggested to be the main region damaged in the subacute phase after CO inhalation. (orig.)

  7. White matter abnormalities in young males with antisocial personality disorder Evidence from voxel-based morphometry-diffeomorphic anatomical registration using exponentiated lie algebra analysis

    Institute of Scientific and Technical Information of China (English)

    Daxing Wu; Ying Zhao; Jian Liao; Huifang Yin; Wei Wang

    2011-01-01

    Voxel-based morphometry-diffeomorphic anatomical registration using exponentiated lie algebra analysis was used to investigate the structural characteristics of white matter in young males with antisocial personality disorder (APD) and healthy controls without APD. The results revealed that APD subjects, relative to healthy subjects, exhibited increased white matter volume in the bilateral prefrontal lobe, right insula, precentral gyrus, bilateral superior temporal gyrus, right postcentral gyrus, right inferior parietal lobule, right precuneus, right middle occipital lobe, right parahippocampal gyrus and bilateral cingulate, and decreased volume in the middle temporal cortex and right cerebellum. The white matter volume in the medial frontal gyrus was significantly correlated with antisocial type scores on the Personality Diagnostic Questionnaire in APD subjects. These experimental findings indicate that white matter abnormalities in several brain areas may contribute to antisocial behaviors in APD subjects.

  8. Gray and white matter density changes in monozygotic and same-sex dizygotic twins discordant for schizophrenia using voxel-based morphometry

    DEFF Research Database (Denmark)

    Hulshoff Pol, HE; Schnack, HG; Mandl, RC

    2006-01-01

    best reflect the genetic and environmental risk factors in the brains of patients with schizophrenia remains unresolved. 1.5-T MRI brain scans of 11 monozygotic and 11 same-sex dizygotic twin-pairs discordant for schizophrenia were compared to 11 monozygotic and 11 same-sex dizygotic healthy control...... twin-pairs using voxel-based morphometry. Linear regression analysis was done in each voxel for the average and difference in gray and white matter density separately, in each twin-pair, with group (discordant, healthy) and zygosity (monozygotic, dizygotic) as between subject variables, and age, sex...... and handedness as covariates. The t-maps (critical threshold value mid R:tmid R: > 6.0, P

  9. A comparison of gray and white matter density in patients with Parkinson's disease dementia and dementia with Lewy bodies using voxel-based morphometry.

    Science.gov (United States)

    Lee, Ji E; Park, Bosuk; Song, Sook K; Sohn, Young H; Park, Hae-Jeong; Lee, Phil Hyu

    2010-01-15

    Despite clinical and neuropsychological similarities between Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB), recent studies have demonstrated that structural and pathological changes are more severe in DLB than in PDD. We used voxel-based morphometry using a 3-T MRI scanner to compare gray and white matter densities in 20 patients with probable PDD and 18 patients with probable DLB, who had similar overall severity of dementia and similar demographic characteristics. The gray matter density was significantly decreased in the left occipital, parietal, and striatal areas in patients with DLB compared with patients with PDD. The white matter density was significantly decreased in bilateral occipital and left occipito-parietal areas in patients with DLB compared with those with PDD. The degree of white and gray matter atrophy was similar in patients with DLB; in contrast, there was markedly less atrophy in the white matter than in the gray matter in patients with PDD. On analyzing the change of WM density relative to that of GM density in patients with DLB compared to those with PDD, the area of WM atrophy in the occipital areas was more extensive than that of GM atrophy. Our data demonstrate that atrophy of both gray and white matter was more severe in patients with DLB and that white matter atrophy relative to gray matter atrophy was less severe in patients with PDD. These data may reflect a difference in the underlying nature of PDD and DLB.

  10. Diagnostic Accuracy of CBCT with Different Voxel Sizes and Intraoral Digital Radiography for Detection of Periapical Bone Lesions: An Ex-Vivo Study

    OpenAIRE

    Shirin Sakhdari; Ahmad Reza Talaeipour; Maziar Talaeipour; Maryam Pazhutan; Sanaz Heidarkhan Tehrani; Mohammad Javad Kharazifard

    2016-01-01

    Objectives: This study sought to assess the diagnostic accuracy of cone beam computed tomography (CBCT) with different voxel sizes and intraoral digital radiography with photostimulable phosphor (PSP) plate for detection of periapical (PA) bone lesions.Materials and Methods: In this ex vivo diagnostic study, one-millimeter defects were created in the alveolar sockets of 15 bone blocks, each with two posterior teeth. A no-defect control group was also included. Digital PA radiographs with PSP ...

  11. Supersize my brain: A cross-sectional voxel-based morphometry study on the association between self-reported dietary restraint and regional grey matter volumes.

    Science.gov (United States)

    van der Laan, Laura N; Charbonnier, Lisette; Griffioen-Roose, Sanne; Kroese, Floor M; van Rijn, Inge; Smeets, Paul A M

    2016-05-01

    Restrained eaters do not eat less than their unrestrained counterparts. Proposed underlying mechanisms are that restrained eaters are more reward sensitive and that they have worse inhibitory control. Although fMRI studies assessed these mechanisms, it is unknown how brain anatomy relates to dietary restraint. Voxel-based morphometry was performed on anatomical scans from 155 normal-weight females to investigate how regional grey matter volume correlates with restraint. A positive correlation was found in several areas, including the parahippocampal gyrus, hippocampus, striatum and the amygdala (bilaterally, pgrey matter volume in reward-related areas and lower grey matter volume in regions involved in inhibition, provides a neuroanatomical underpinning of theories relating restraint to increased reward sensitivity and reduced inhibitory capacity.

  12. Accuracy of linear measurements from cone-beam computed tomography-derived surface models of different voxel sizes

    NARCIS (Netherlands)

    Damstra, Janalt; Fourie, Zacharias; Huddleston Slater, James J R; Ren, Yijin

    2010-01-01

    INTRODUCTION: The aims of this study were to determine the linear accuracy of 3-dimensional surface models derived from a commercially available cone-beam computed tomography (CBCT) dental imaging system and volumetric rendering software and to investigate the influence of voxel resolution on the li

  13. Accuracy of linear measurements from cone-beam computed tomography-derived surface models of different voxel sizes

    NARCIS (Netherlands)

    Damstra, Janalt; Fourie, Zacharias; Huddleston Slater, James J R; Ren, Yijin

    2010-01-01

    INTRODUCTION: The aims of this study were to determine the linear accuracy of 3-dimensional surface models derived from a commercially available cone-beam computed tomography (CBCT) dental imaging system and volumetric rendering software and to investigate the influence of voxel resolution on the li

  14. Linear and curvilinear correlations of brain gray matter volume and density with age using voxel-based morphometry with the Akaike information criterion in 291 healthy children.

    Science.gov (United States)

    Taki, Yasuyuki; Hashizume, Hiroshi; Thyreau, Benjamin; Sassa, Yuko; Takeuchi, Hikaru; Wu, Kai; Kotozaki, Yuka; Nouchi, Rui; Asano, Michiko; Asano, Kohei; Fukuda, Hiroshi; Kawashima, Ryuta

    2013-08-01

    We examined linear and curvilinear correlations of gray matter volume and density in cortical and subcortical gray matter with age using magnetic resonance images (MRI) in a large number of healthy children. We applied voxel-based morphometry (VBM) and region-of-interest (ROI) analyses with the Akaike information criterion (AIC), which was used to determine the best-fit model by selecting which predictor terms should be included. We collected data on brain structural MRI in 291 healthy children aged 5-18 years. Structural MRI data were segmented and normalized using a custom template by applying the diffeomorphic anatomical registration using exponentiated lie algebra (DARTEL) procedure. Next, we analyzed the correlations of gray matter volume and density with age in VBM with AIC by estimating linear, quadratic, and cubic polynomial functions. Several regions such as the prefrontal cortex, the precentral gyrus, and cerebellum showed significant linear or curvilinear correlations between gray matter volume and age on an increasing trajectory, and between gray matter density and age on a decreasing trajectory in VBM and ROI analyses with AIC. Because the trajectory of gray matter volume and density with age suggests the progress of brain maturation, our results may contribute to clarifying brain maturation in healthy children from the viewpoint of brain structure.

  15. Resident Assistant Mattering: Do Placement and Community Size Matter?

    Science.gov (United States)

    Stoner, James C.; Zhang, Yi

    2017-01-01

    A sense of mattering among college students has been found to have positive outcomes, including lower levels of anxiety and depression as well as increased self-esteem, wellness, happiness, and job satisfaction. However, the feeling of mattering among Resident Assistants (RAs) has received little attention in literature. This quantitative study…

  16. Numerical transcoding proficiency in 10-year-old schoolchildren is associated with grey-matter interindividual differences: A voxel-based morphometry study

    Directory of Open Access Journals (Sweden)

    Amélie eLubin

    2013-04-01

    Full Text Available Are individual differences in numerical performance sustained by variations in grey matter volume in schoolchildren? To our knowledge, this challenging question for neuroeducation has not yet been investigated in typical development. We used the Voxel-Based Morphometry method to search for possible structural brain differences between two groups of 10-year-old schoolchildren (N=22 whose performance differed only in numerical transcoding between analog and symbolic systems. The results indicated that children with low numerical proficiency have less grey matter volume in the parietal (particularly in the left intraparietal sulcus and the bilateral angular gyri and occipito-temporal areas. All the identified regions have previously been shown to be functionally involved in transcoding between analog and symbolic numerical systems. Our data contribute to a better understanding of the intertwined relationships between mathematics learning and brain structure in healthy schoolchildren.

  17. Cerebral and cerebellar gray matter reduction in first-episode patients with major depressive disorder: A voxel-based morphometry study

    Energy Technology Data Exchange (ETDEWEB)

    Peng Jing, E-mail: ppengjjing@sina.com.cn [Department of Radiology, Xuanwu Hospital of Capital Medical University, No. 45, Chang-Chun St, Xuanwu District, Beijing 100053 (China); Liu Jiangtao, E-mail: Liujiangtao813@sina.com [Department of Radiology, Xuanwu Hospital of Capital Medical University, No. 45, Chang-Chun St, Xuanwu District, Beijing 100053 (China); Nie Binbin, E-mail: niebb@ihep.ac.cn [Institute of High Energy Physics, Chinese Academy of Sciences, PO Box 918, Yu-Quan St, Shijingshan District, Beijing 100049 (China); Li Yang, E-mail: Liyang2007428@hotmail.com [Department of Psychiatry, Anding Hospital of Capital Medical University, No. 5, An Kang Hutong, Deshengmen wai, Xicheng District, Beijing 100088 (China); Shan Baoci, E-mail: shanbc@ihep.ac.cn [Institute of High Energy Physics, Chinese Academy of Sciences, PO Box 918, Yu-Quan St, Shijingshan District, Beijing 100049 (China); Wang Gang, E-mail: gangwang@gmail.com [Department of Psychiatry, Anding Hospital of Capital Medical University, No. 5, An Kang Hutong, Deshengmen wai, Xicheng District, Beijing 100088 (China); Li Kuncheng, E-mail: likuncheng1955@yahoo.com.cn [Department of Radiology, Xuanwu Hospital of Capital Medical University, No. 45, Chang-Chun St, Xuanwu District, Beijing 100053 (China)

    2011-11-15

    Purpose: To investigate cerebral and cerebellar gray matter abnormalities in patients with first-episode major depressive disorder (MDD). Materials and methods: We examined the structural difference in regional gray matter density (GMD) between 22 first-episode MDD patients and 30 age-, gender- and education-matched healthy controls by optimized voxel-based morphometry (VBM) based on magnetic resonance imaging. Results: Compared with healthy controls, MDD patients showed decreased GMD in the right medial and left lateral orbitofrontal cortex, right dorsolateral prefrontal cortex (DLPFC), bilateral temporal pole, right superior temporal gyrus, bilateral anterior insular cortex, left parahippocampal gyrus, and left cerebellum. In addition, in MDD patients, there was a negative correlation between GMD values of the right DLPFC and the score of the depression rating scale. Conclusions: Our findings provided additional support for the involvement of limbic-cortical circuits in the pathophysiology of MDD and preliminary evidence that a defect involving the cerebellum may also be implicated.

  18. Grey matter volume abnormalities in patients with bipolar I depressive disorder and unipolar depressive disorder: a voxel-based morphometry study.

    Science.gov (United States)

    Cai, Yi; Liu, Jun; Zhang, Li; Liao, Mei; Zhang, Yan; Wang, Lifeng; Peng, Hongjun; He, Zhong; Li, Zexuan; Li, Weihui; Lu, Shaojia; Ding, Yuqiang; Li, Lingjiang

    2015-02-01

    Bipolar disorder and unipolar depressive disorder (UD) may be different in brain structure. In the present study, we performed voxel-based morphometry (VBM) to quantify the grey matter volumes in 23 patients with bipolar I depressive disorder (BP1) and 23 patients with UD, and 23 age-, gender-, and education-matched healthy controls (HCs) using magnetic resonance imaging. We found that compared with the HC and UD groups, the BP1 group showed reduced grey matter volumes in the right inferior frontal gyrus and middle cingulate gyrus, while the UD group showed reduced volume in the right inferior frontal gyrus compared to HCs. In addition, correlation analyses revealed that the grey matter volumes of these regions were negatively correlated with the Hamilton depression rating scores. Taken together, the results of our study suggest that decreased grey matter volume of the right inferior frontal gyrus is a common abnormality in BP1 and UD, and decreased grey matter volume in the right middle cingulate gyrus may be specific to BP1.

  19. Grey matter, an endophenotype for schizophrenia? A voxel-based morphometry study in siblings of patients with schizophrenia

    NARCIS (Netherlands)

    van der Velde, Jorien; Gromann, Paula M.; Swart, Marte; de Haan, Lieuwe; Wiersma, Durk; Bruggeman, Richard; Krabbendam, Lydia; Aleman, Andre

    2015-01-01

    Background Grey matter, both volume and concentration, has been proposed as an endophenotype for schizophrenia given a number of reports of grey matter abnormalities in relatives of patients with schizophrenia. However, previous studies on grey matter abnormalities in relatives have produced inconsi

  20. The Gray Matter Volume of the Amygdala Is Correlated with the Perception of Melodic Intervals: A Voxel-Based Morphometry Study

    OpenAIRE

    Xueting Li; Alain De Beuckelaer; Jiahui Guo; Feilong Ma; Miao Xu; Jia Liu

    2014-01-01

    Music is not simply a series of organized pitches, rhythms, and timbres, it is capable of evoking emotions. In the present study, voxel-based morphometry (VBM) was employed to explore the neural basis that may link music to emotion. To do this, we identified the neuroanatomical correlates of the ability to extract pitch interval size in a music segment (i.e., interval perception) in a large population of healthy young adults (N = 264). Behaviorally, we found that interval perception was corre...

  1. Estimating radiation doses from multidetector CT using Monte Carlo simulations: effects of different size voxelized patient models on magnitudes of organ and effective dose.

    Science.gov (United States)

    DeMarco, J J; Cagnon, C H; Cody, D D; Stevens, D M; McCollough, C H; Zankl, M; Angel, E; McNitt-Gray, M F

    2007-05-07

    The purpose of this work is to examine the effects of patient size on radiation dose from CT scans. To perform these investigations, we used Monte Carlo simulation methods with detailed models of both patients and multidetector computed tomography (MDCT) scanners. A family of three-dimensional, voxelized patient models previously developed and validated by the GSF was implemented as input files using the Monte Carlo code MCNPX. These patient models represent a range of patient sizes and ages (8 weeks to 48 years) and have all radiosensitive organs previously identified and segmented, allowing the estimation of dose to any individual organ and calculation of patient effective dose. To estimate radiation dose, every voxel in each patient model was assigned both a specific organ index number and an elemental composition and mass density. Simulated CT scans of each voxelized patient model were performed using a previously developed MDCT source model that includes scanner specific spectra, including bowtie filter, scanner geometry and helical source path. The scan simulations in this work include a whole-body scan protocol and a thoracic CT scan protocol, each performed with fixed tube current. The whole-body scan simulation yielded a predictable decrease in effective dose as a function of increasing patient weight. Results from analysis of individual organs demonstrated similar trends, but with some individual variations. A comparison with a conventional dose estimation method using the ImPACT spreadsheet yielded an effective dose of 0.14 mSv mAs(-1) for the whole-body scan. This result is lower than the simulations on the voxelized model designated 'Irene' (0.15 mSv mAs(-1)) and higher than the models 'Donna' and 'Golem' (0.12 mSv mAs(-1)). For the thoracic scan protocol, the ImPACT spreadsheet estimates an effective dose of 0.037 mSv mAs(-1), which falls between the calculated values for Irene (0.042 mSv mAs(-1)) and Donna (0.031 mSv mAs(-1)) and is higher relative

  2. Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size

    Science.gov (United States)

    King, Richard B.

    2016-01-01

    Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females) and annual growth increments of individuals of unknown age (1,152 males, 730 females). We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631–820 mm snout-vent length in males and from 835–1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further investigation. PMID

  3. Matters of fiber size and myonuclear domain

    DEFF Research Database (Denmark)

    Karlsen, Anders; Couppé, Christian; Andersen, Jesper L.;

    2015-01-01

    INTRODUCTION: The relationship between fiber size and myonuclear content is understood poorly. METHODS: Biopsy cross-sections from young and old trained and untrained healthy individuals were analyzed for fiber area and myonuclei, and 2 fiber size-dependent cluster analyses were performed. RESULTS......: Comparing fibers of similar size, no effect of training or age was found for myonuclear domain. There was a linear relationship between fiber area and myonuclei per fiber (r=0.99; Pfiber area and domain (r=0.97-0.99; P... in fibers fibers below 3,000 μm(2) was observed in the old. DISCUSSION: These findings suggest that age-related reductions in myonuclear domain size could be explained by a larger proportion of small fibers and highlight the usefulness of fiber size...

  4. Windows in Low Energy Houses. Size Matters

    Energy Technology Data Exchange (ETDEWEB)

    Persson, Mari-Louise

    2004-06-01

    A generally accepted way of building passive houses has been to have small windows facing north and a large glass facade to the south. This is to minimize losses on the north side while gaining as much solar heat as possible on the south. In spring 2001, twenty terraced houses were built outside Goeteborg partly in this way. The indoor temperature is kept at a comfortable level by passive methods, using solar gains and internal gains from household appliances and occupants. Heat losses are very low, since the building envelope is well insulated and since modern coated triple-glazed windows have been installed. The purpose of this work is to investigate how decreasing the window size facing south and increasing the window size facing north in low energy houses will influence the energy consumption and maximum power needed to keep the indoor temperature between 23 and 26 deg C. Different climates and orientations have been investigated and so have the influence of occupancy and window type. A dynamic building simulation tool, DEROB, has been used and the simulations indicate an extremely low energy demand for the houses. The results show that the size of the energy efficient windows does not have a major influence on the heating demand in winter, but is of relevant signification looking at the cooling need in summer. This indicates that instead of the traditional technique of building passive houses it is possible to enlarge the window area facing north and get better lighting conditions. To decrease the energy need for cooling, there is an optimal window size facing south that is smaller than the original size of the investigated buildings.

  5. Influence of parameter settings in voxel-based morphometry 8. Using DARTEL and region-of-interest on reproducibility in gray matter volumetry.

    Science.gov (United States)

    Goto, M; Abe, O; Aoki, S; Hayashi, N; Miyati, T; Takao, H; Matsuda, H; Yamashita, F; Iwatsubo, T; Mori, H; Kunimatsu, A; Ino, K; Yano, K; Ohtomo, K

    2015-01-01

    To investigate whether reproducibility of gray matter volumetry is influenced by parameter settings for VBM 8 using Diffeomorphic Anatomical Registration Through Exponentiated Lie Algebra (DARTEL) with region-of-interest (ROI) analyses. We prepared three-dimensional T1-weighted magnetic resonance images (3D-T1WIs) of 21 healthy subjects. All subjects were imaged with each of five MRI systems. Voxel-based morphometry 8 (VBM 8) and WFU PickAtlas software were used for gray matter volumetry. The bilateral ROI labels used were those provided as default settings with the software: Frontal Lobe, Hippocampus, Occipital Lobe, Orbital Gyrus, Parietal Lobe, Putamen, and Temporal Lobe. All 3D-T1WIs were segmented to gray matter with six parameters of VBM 8, with each parameter having between three and eight selectable levels. Reproducibility was evaluated as the standard deviation (mm³) of measured values for the five MRI systems. Reproducibility was influenced by 'Bias regularization (BiasR)', 'Bias FWHM', and 'De-noising filter' settings, but not by 'MRF weighting', 'Sampling distance', or 'Warping regularization' settings. Reproducibility in BiasR was influenced by ROI. Superior reproducibility was observed in Frontal Lobe with the BiasR1 setting, and in Hippocampus, Parietal Lobe, and Putamen with the BiasR3*, BiasR1, and BiasR5 settings, respectively. Reproducibility of gray matter volumetry was influenced by parameter settings in VBM 8 using DARTEL and ROI. In multi-center studies, the use of appropriate settings in VBM 8 with DARTEL results in reduced scanner effect.

  6. Common and distinct patterns of grey-matter volume alteration in major depression and bipolar disorder: evidence from voxel-based meta-analysis.

    Science.gov (United States)

    Wise, T; Radua, J; Via, E; Cardoner, N; Abe, O; Adams, T M; Amico, F; Cheng, Y; Cole, J H; de Azevedo Marques Périco, C; Dickstein, D P; Farrow, T F D; Frodl, T; Wagner, G; Gotlib, I H; Gruber, O; Ham, B J; Job, D E; Kempton, M J; Kim, M J; Koolschijn, P C M P; Malhi, G S; Mataix-Cols, D; McIntosh, A M; Nugent, A C; O'Brien, J T; Pezzoli, S; Phillips, M L; Sachdev, P S; Salvadore, G; Selvaraj, S; Stanfield, A C; Thomas, A J; van Tol, M J; van der Wee, N J A; Veltman, D J; Young, A H; Fu, C H; Cleare, A J; Arnone, D

    2016-05-24

    Finding robust brain substrates of mood disorders is an important target for research. The degree to which major depression (MDD) and bipolar disorder (BD) are associated with common and/or distinct patterns of volumetric changes is nevertheless unclear. Furthermore, the extant literature is heterogeneous with respect to the nature of these changes. We report a meta-analysis of voxel-based morphometry (VBM) studies in MDD and BD. We identified studies published up to January 2015 that compared grey matter in MDD (50 data sets including 4101 individuals) and BD (36 data sets including 2407 individuals) using whole-brain VBM. We used statistical maps from the studies included where available and reported peak coordinates otherwise. Group comparisons and conjunction analyses identified regions in which the disorders showed common and distinct patterns of volumetric alteration. Both disorders were associated with lower grey-matter volume relative to healthy individuals in a number of areas. Conjunction analysis showed smaller volumes in both disorders in clusters in the dorsomedial and ventromedial prefrontal cortex, including the anterior cingulate cortex and bilateral insula. Group comparisons indicated that findings of smaller grey-matter volumes relative to controls in the right dorsolateral prefrontal cortex and left hippocampus, along with cerebellar, temporal and parietal regions were more substantial in major depression. These results suggest that MDD and BD are characterised by both common and distinct patterns of grey-matter volume changes. This combination of differences and similarities has the potential to inform the development of diagnostic biomarkers for these conditions.Molecular Psychiatry advance online publication, 24 May 2016; doi:10.1038/mp.2016.72.

  7. Adaptive Dynamics of Regulatory Networks: Size Matters

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available To accomplish adaptability, all living organisms are constructed of regulatory networks on different levels which are capable to differentially respond to a variety of environmental inputs. Structure of regulatory networks determines their phenotypical plasticity, that is, the degree of detail and appropriateness of regulatory replies to environmental or developmental challenges. This regulatory network structure is encoded within the genotype. Our conceptual simulation study investigates how network structure constrains the evolution of networks and their adaptive abilities. The focus is on the structural parameter network size. We show that small regulatory networks adapt fast, but not as good as larger networks in the longer perspective. Selection leads to an optimal network size dependent on heterogeneity of the environment and time pressure of adaptation. Optimal mutation rates are higher for smaller networks. We put special emphasis on discussing our simulation results on the background of functional observations from experimental and evolutionary biology.

  8. Adaptive Dynamics of Regulatory Networks: Size Matters

    Directory of Open Access Journals (Sweden)

    Martinetz Thomas

    2009-01-01

    Full Text Available To accomplish adaptability, all living organisms are constructed of regulatory networks on different levels which are capable to differentially respond to a variety of environmental inputs. Structure of regulatory networks determines their phenotypical plasticity, that is, the degree of detail and appropriateness of regulatory replies to environmental or developmental challenges. This regulatory network structure is encoded within the genotype. Our conceptual simulation study investigates how network structure constrains the evolution of networks and their adaptive abilities. The focus is on the structural parameter network size. We show that small regulatory networks adapt fast, but not as good as larger networks in the longer perspective. Selection leads to an optimal network size dependent on heterogeneity of the environment and time pressure of adaptation. Optimal mutation rates are higher for smaller networks. We put special emphasis on discussing our simulation results on the background of functional observations from experimental and evolutionary biology.

  9. Grey matter density decreases as well as increases in patients with classic galactosemia : a voxel-based morphometry study

    NARCIS (Netherlands)

    Timmers, Inge; van der Korput, Lisanne D; Jansma, Bernadette M; Rubio-Gozalbo, M Estela

    2016-01-01

    Brain impairments have been observed in patients with classic galactosemia, an inherited metabolic disorder resulting in a particular neuro-cognitive profile. Neuroimaging studies showed abnormalities such as diffuse white mater (WM) abnormalities and grey matter (GM) atrophy. Our current study anal

  10. A Voxel-based Morphometric Analysis of Cerebral Gray Matter in Subcortical Ischemic Vascular Dementia Patients and Normal Aged Controls

    Directory of Open Access Journals (Sweden)

    Chuanming Li, Hanjian Du, Jian Zheng, Jian Wang

    2011-01-01

    Full Text Available BACKGROUND AND PURPOSE: The present study was designed to detect the abnormalities of the cerebral grey-matter density in subcortical ischemic vascular dementia patients by FSL-VBM method to promote the early diagnosis of it.METHODS: Nine subcortical ischemic vascular dementia patients and nine age-matched normal controls underwent MRI brain structure scanning that was performed on a SIEMENS AVANTO 1.5 Tesla scanner and standard T1-weighted high-resolution anatomic scans of MPRAGE sequence were obtained. The 3-demensional MPRAGE images were processed with FSL-VBM package and the cerebral gray matter density was compared between the subcortical ischemic vascular dementia patients and normal controls.RESULTS: Compared with the normal control group, the cerebral gray matter density of subcortical ischemic vascular dementia patients was found significantly decreasing, including brain regions of thalamus, parietal lobe, frontal lobe and temporal lobe (P<0.05.CONCLUSIONS: The cerebral gray matter density alterations have closed correlation with cognitive dysfunction in subcortical ischemic vascular dementia patient and can be detected by MRI. MRI has some potential value in the diagnosis of them.

  11. Collective resonances in plasmonic crystals: Size matters

    CERN Document Server

    Rodriguez, S R K; Berrier, A; Rivas, J Gomez

    2013-01-01

    Periodic arrays of metallic nanoparticles may sustain Surface Lattice Resonances (SLRs), which are collective resonances associated with the diffractive coupling of Localized Surface Plasmon Resonances (LSPRs). By investigating a series of arrays with varying number of particles, we traced the evolution of SLRs to its origins. Polarization resolved extinction spectra of arrays formed by a few nanoparticles were measured, and found to be in very good agreement with calculations based on a coupled dipole model. Finite size effects on the optical properties of the arrays are observed, and our results provide insight into the characteristic length scales for collective plasmonic effects: for arrays smaller than 5 x 5 particles, the Q-factors of SLRs are lower than those of LSPRs; for arrays larger than 20 x 20 particles, the Q-factors of SLRs saturate at a much larger value than those of LSPRs; in between, the Q-factors of SLRs are an increasing function of the number of particles in the array.

  12. Voxel-based morphometry reveals increased gray matter density in Broca's area in male symphony orchestra musicians.

    Science.gov (United States)

    Sluming, Vanessa; Barrick, Thomas; Howard, Matthew; Cezayirli, Enis; Mayes, Andrew; Roberts, Neil

    2002-11-01

    Broca's area is a major neuroanatomical substrate for spoken language and various musically relevant abilities, including visuospatial and audiospatial localization. Sight reading is a musician-specific visuospatial analysis task, and spatial ability is known to be amenable to training effects. Musicians have been reported to perform significantly better than nonmusicians on spatial ability tests, which is supported by our findings with the Benton judgement of line orientation (JOL) test (P musical performance promotes use-dependent retention, and possibly expansion, of gray matter involving Broca's area and that this provides further support for shared neural substrates underpinning expressive output in music and language.

  13. Individual differences in local gray and white matter volumes reflect differences in temperament and character: a voxel-based morphometry study in healthy young females.

    Science.gov (United States)

    Van Schuerbeek, Peter; Baeken, Chris; De Raedt, Rudi; De Mey, Johan; Luypaert, Rob

    2011-01-31

    The psychobiological personality model of Cloninger distinguishes four heritable temperament traits (harm avoidance (HA), novelty seeking (NS), reward dependence (RD) and persistence (P)) and three character traits (self-directedness (SD), cooperativeness (CO) and self-transcendence (ST)) which develop during lifetime. Prior research already showed that individual differences in temperament are reflected in structural variances in specific brain areas. In this study, we used voxel-based morphometry (VBM) to correlate the different temperament and character traits with local gray and white matter volumes (GMV and WMV) in young healthy female volunteers. We found correlations between the temperament traits and GMV and WMV in the frontal, temporal and limbic regions involved in controlling and generating the corresponding behavior as proposed in Cloninger's theory: anxious for HA, impulsive for NS, reward-directed for RD and goal-directed for P. The character traits correlated with GMV and WMV in the frontal, temporal and limbic regions involved in the corresponding cognitive tasks: self-reflection for SD, mentalizing and empathizing with others for CO and religious belief for ST. This study shows that individual variations in brain morphology can be related to the temperament and character dimensions, and lends support to the hypothesis of a neurobiological basis of personality traits.

  14. A voxel-based morphometry (VBM) analysis of regional grey and white matter volume abnormalities within the speech production network of children who stutter.

    Science.gov (United States)

    Beal, Deryk S; Gracco, Vincent L; Brettschneider, Jane; Kroll, Robert M; De Nil, Luc F

    2013-09-01

    It is well documented that neuroanatomical differences exist between adults who stutter and their fluently speaking peers. Specifically, adults who stutter have been found to have more grey matter volume (GMV) in speech relevant regions including inferior frontal gyrus, insula and superior temporal gyrus (Beal et al., 2007; Song et al., 2007). Despite stuttering having its onset in childhood only one study has investigated the neuroanatomical differences between children who do and do not stutter. Chang et al. (2008) reported children who stutter had less GMV in the bilateral inferior frontal gyri and middle temporal gyrus relative to fluently speaking children. Thus it appears that children who stutter present with unique neuroanatomical abnormalities as compared to those of adults who stutter. In order to better understand the neuroanatomical correlates of stuttering earlier in its development, near the time of onset, we used voxel-based morphometry to examine volumetric differences between 11 children who stutter and 11 fluent children. Children who stutter had less GMV in the bilateral inferior frontal gyri and left putamen but more GMV in right Rolandic operculum and superior temporal gyrus relative to fluent children. Children who stutter also had less white matter volume bilaterally in the forceps minor of the corpus callosum. We discuss our findings of widespread anatomic abnormalities throughout the cortical network for speech motor control within the context of the speech motor skill limitations identified in people who stutter (Namasivayam and van Lieshout, 2008; Smits-Bandstra et al., 2006).

  15. Regional gray matter correlates of memory for emotion-laden words in middle-aged and older adults: A voxel-based morphometry study.

    Science.gov (United States)

    Saarela, Carina; Joutsa, Juho; Laine, Matti; Parkkola, Riitta; Rinne, Juha O; Karrasch, Mira

    2017-01-01

    Emotional content is known to enhance memory in a content-dependent manner in healthy populations. In middle-aged and older adults, a reduced preference for negative material, or even an enhanced preference for positive material has been observed. This preference seems to be modulated by the emotional arousal that the material evokes. The neuroanatomical basis for emotional memory processes is, however, not well understood in middle-aged and older healthy people. Previous research on local gray matter correlates of emotional memory in older populations has mainly been conducted with patients suffering from various neurodegenerative diseases. To our knowledge, this is the first study to examine regional gray matter correlates of immediate free recall and recognition memory of intentionally encoded positive, negative, and emotionally neutral words using voxel-based morphometry (VBM) in a sample of 50-to-79-year-old cognitively intact normal adults. The behavioral analyses yielded a positivity bias in recognition memory, but not in immediate free recall. No associations with memory performance emerged from the region-of-interest (ROI) analyses using amygdalar and hippocampal volumes. Controlling for total intracranial volume, age, and gender, the whole-brain VBM analyses showed statistically significant associations between immediate free recall of negative words and volumes in various frontal regions, between immediate free recall of positive words and cerebellar volume, and between recognition memory of positive words and primary visual cortex volume. The findings indicate that the neural areas subserving memory for emotion-laden information encompass posterior brain areas, including the cerebellum, and that memory for emotion-laden information may be driven by cognitive control functions.

  16. White matter neuroplastic changes in long-term trained players of the game of "Baduk" (GO): a voxel-based diffusion-tensor imaging study.

    Science.gov (United States)

    Lee, Boreom; Park, Ji-Young; Jung, Wi Hoon; Kim, Hee Sun; Oh, Jungsu S; Choi, Chi-Hoon; Jang, Joon Hwan; Kang, Do-Hyung; Kwon, Jun Soo

    2010-08-01

    Currently, one of the most challenging issues in modern neuroscience is learning-induced neural plasticity. Many researchers have identified activation-dependent structural brain plasticity in gray and white matter. The game of Baduk is known to require many cognitive processes, and long-term training in such processes would be expected to cause structural changes in related brain areas. We conducted voxel-based analyses of diffusion-tensor imaging (DTI) data and found that, compared to inexperienced controls, long-term trained Baduk players developed larger regions of white matter with increased fractional anisotropy (FA) values in the frontal, cingulum, and striato-thalamic areas that are related to attentional control, working memory, executive regulation, and problem-solving. In addition, inferior temporal regions with increased FA indicate that Baduk experts tend to develop a task-specific template for the game, as compared to controls. In contrast, decreased FA found in dorsolateral premotor and parietal areas indicate that Baduk experts were less likely than were controls to use structures related to load-dependent memory capacity. Right-side dominance in Baduk experts suggests that the tasks involved are mainly spatial processes. Altogether, long-term Baduk training appears to cause structural brain changes associated with many of the cognitive aspects necessary for game play, and investigation of the mechanism underpinning such changes might be helpful for improving higher-order cognitive capacities, such as learning, abstract reasoning, and self-control, which can facilitate education and cognitive therapies. Copyright 2010 Elsevier Inc. All rights reserved.

  17. Patterns of Gray Matter Abnormalities in Idiopathic Generalized Epilepsy: A Meta-Analysis of Voxel-Based Morphology Studies

    Science.gov (United States)

    Zeng, Hongwu; He, Xiaoming; Li, Feng; Zhang, Jian; Huang, Bingsheng

    2017-01-01

    Objective We aimed to identify the consistent regions of gray matter volume (GMV) abnormalities in idiopathic generalized epilepsy (IGE), and to study the difference of GMV abnormalities among IGE subsyndromes by applying activation likelihood estimation (ALE) meta-analysis. Methods A systematic review of VBM studies on GMV of patients with absence epilepsy (AE), juvenile myoclonic epilepsy (JME), IGE and controls indexed in PubMed and ScienceDirect from January 1999 to June 2016 was conducted. A total of 12 IGE studies, including 7 JME and 3 AE studies, were selected. Meta-analysis was performed on these studies by using the pooled and within-subtypes analysis (www.brainmap.org). Based on the above results, between-subtypes contrast analysis was carried out to detect the abnormal GMV regions common in and unique to each subtype as well. Results IGE demonstrated significant GMV increase in right ventral lateral nucleus (VL) and right medial frontal gyrus, and significant GMV decrease in bilateral pulvinar. For JME, significant GMV increase was seen in right medial frontal gyrus, right anterior cingulate cortex (ACC), while significant GMV decrease was found in right pulvinar. In AE, the most significant GMV increase was found in right VL, and slight GMV reduction was seen in right medial dorsal nucleus, right subcallosal gyrus, left caudate and left precuneus. No overlapped and unique regions with significant GMV abnormalities were found between JME and AE. Significance This meta-analysis demonstrated that thalamo-frontal network was a structure with significant GMV abnormality in IGE, and the IGE subsyndromes showed different GMV abnormal regions. These observations may provide instructions on the clinical diagnosis of IGE. PMID:28060866

  18. Avaliação de doses referenciais obtidas com exames de tomografia computadorizada de feixe cônico adquiridos com diferentes tamanhos de voxel Evaluation of referential dosages obtained by Cone-Beam Computed Tomography examinations acquired with different voxel sizes

    Directory of Open Access Journals (Sweden)

    Marianna Guanaes Gomes Torres

    2010-10-01

    Full Text Available OBJETIVO: o objetivo deste estudo reside na avaliação do produto dose-área (DAP e das doses de entrada na pele (DEP, empregando protocolos com tamanho de voxel diferente, obtidos com o aparelho de Tomografia Computadorizada de Feixe Cônico (TCFC i-CAT, a fim de determinar melhores parâmetros baseados nos princípios da radioproteção. MÉTODOS: para medição do DEP foi utilizada uma câmara de ionização do tipo lápis, e para o DAP foi utilizado um aparelho PTW. Quatro protocolos foram testados, a saber: (1 40 seg., voxel de 0,2mm e 46,72mAs; (2 40 seg., voxel de 0,25mm e 46,72mAs; (3 20 seg., voxel de 0,3mm e 23,87mAs; (4 20 seg., voxel de 0,4mm e 23,87mAs. A quilovoltagem permaneceu constante (120KVp. RESULTADOS: detectou-se diferença estatisticamente significativa (pObjectives: The aim of this study was to evaluate the dose-area product (DAP and the entrance skin dose (ESD, using protocols with different voxel sizes, obtained with i-CAT Cone-Beam Computed Tomography (CBCT, to determine the best parameters based on radioprotection principles. METHODS: A pencil-type ionization chamber was used to measure the ESD and a PTW device was used to measure the DAP. Four protocols were tested: (1 40s, 0.2 mm voxel and 46.72 mAs; (2 40s, 0.25 mm voxel and 46.72 mAs; (3 20s, 0.3 mm voxel and 23.87 mAs; (4 20s, 0.4 mm voxel and 23.87 mAs. The kilovoltage remained constant (120kVp. RESULTS: A significant statistical difference (p<0.001 was found among the four protocols for both methods of radiation dosage evaluation (DAP and ESD. For DAP evaluation, protocols 2 and 3 presented a statistically significant difference, and it was not possible to detect which of the protocols for ESD evaluation promoted this result. CONCLUSIONS: DAP and ESD are evaluation methods for radiation dose for Cone-Beam Computed Tomography, and more studies are necessary to explain such result. The voxel size alone does not affect the radiation dose in CBCT (i

  19. Finite size effects in Neutron Star and Nuclear matter simulations

    CERN Document Server

    Molinelli, P A Giménez

    2014-01-01

    In this work we study molecular dynamics simulations of symmetric nuclear matter using a semi-classical nucleon interaction model. We show that, at sub-saturation densities and low temperatures, the solutions are non-homogeneous structures reminiscent of the ``nuclear pasta'' phases expected in Neutron Star Matter simulations, but shaped by artificial aspects of the simulations. We explore different geometries for the periodic boundary conditions imposed on the simulation cell: cube, hexagonal prism and truncated octahedron. We find that different cells may yield different solutions for the same physical conditions (i.e. density and temperature). The particular shape of the solution at a given density can be predicted analytically by energy minimization. We also show that even if this behavior is due to finite size effects, it does not mean that it vanishes for very large systems and it actually is independent of the system size: The system size sets the only characteristic length scale for the inhomogeneitie...

  20. Finite size effects in neutron star and nuclear matter simulations

    Energy Technology Data Exchange (ETDEWEB)

    Giménez Molinelli, P.A., E-mail: pagm@df.uba.ar; Dorso, C.O.

    2015-01-15

    In this work we study molecular dynamics simulations of symmetric nuclear and neutron star matter using a semi-classical nucleon interaction model. Our aim is to gain insight on the nature of the so-called “finite size effects”, unavoidable in this kind of simulations, and to understand what they actually affect. To do so, we explore different geometries for the periodic boundary conditions imposed on the simulation cell: cube, hexagonal prism and truncated octahedron. For nuclear matter simulations we show that, at sub-saturation densities and low temperatures, the solutions are non-homogeneous structures reminiscent of the “nuclear pasta” phases expected in neutron star matter simulations, but only one structure per cell and shaped by specific artificial aspects of the simulations—for the same physical conditions (i.e. number density and temperature) different cells yield different solutions. The particular shape of the solution at low enough temperature and a given density can be predicted analytically by surface minimization. We also show that even if this behavior is due to the imposition of periodic boundary conditions on finite systems, this does not mean that it vanishes for very large systems, and it is actually independent of the system size. We conclude that, for nuclear matter simulations, the cells' size sets the only characteristic length scale for the inhomogeneities, and the geometry of the periodic cell determines the shape of those inhomogeneities. To model neutron star matter we add a screened Coulomb interaction between protons, and perform simulations in the three cell geometries. Our simulations indeed produce the well known nuclear pasta, with (in most cases) several structures per cell. However, we find that for systems not too large results are affected by finite size in different ways depending on the geometry of the cell. In particular, at the same certain physical conditions and system size, the hexagonal prism yields a

  1. Size Does Matter (in P2P Live Streaming)

    CERN Document Server

    Hegde, Nidhi; Perino, Diego

    2009-01-01

    Optimal dissemination schemes have previously been studied for peer-to-peer live streaming applications. Live streaming being a delay-sensitive application, fine tuning of dissemination parameters is crucial. In this report, we investigate optimal sizing of chunks, the units of data exchange, and probe sets, the number peers a given node probes before transmitting chunks. Chunk size can have significant impact on diffusion rate (chunk miss ratio), diffusion delay, and overhead. The size of the probe set can also affect these metrics, primarily through the choices available for chunk dissemination. We perform extensive simulations on the so-called random-peer, latest-useful dissemination scheme. Our results show that size does matter, with the optimal size being not too small in both cases.

  2. Nearsightedness of Electronic Matter and the Size of Viruses

    CERN Document Server

    Geng, W T

    2010-01-01

    I conjecture that the nearsightedness of component electronic matter largely determines the size of a virus. These two length scales, one from physics and one from biochemistry, are in fact the same dimension which connects our quantum and everyday worlds. Learning how viruses interact with microscopic molecules and macroscopic biological cells might help us understand the quantum-to-classical transition in general cases of multiscale phenomena.

  3. Size did not matter: An evolutionary account of the variation in penis size and size anxiety

    OpenAIRE

    Menelaos Apostolou

    2016-01-01

    The human penis exhibits considerable variation in size, while a substantial proportion of the adult male population experiences size anxiety. This paper employs an evolutionary framework in order to understand this variation, as well as the concern men exhibit about the adequacy of the size of their penis. It is argued that female choice has been one important sexual selection force, responsible for shaping the size of the penis. However, this force has been relatively weak, because women do...

  4. Size did not matter: An evolutionary account of the variation in penis size and size anxiety

    Directory of Open Access Journals (Sweden)

    Menelaos Apostolou

    2016-12-01

    Full Text Available The human penis exhibits considerable variation in size, while a substantial proportion of the adult male population experiences size anxiety. This paper employs an evolutionary framework in order to understand this variation, as well as the concern men exhibit about the adequacy of the size of their penis. It is argued that female choice has been one important sexual selection force, responsible for shaping the size of the penis. However, this force has been relatively weak, because women do not consider the size of their partners’ penis to be the most important determinant of their sexual satisfaction. Also, in ancestral human societies, sexual satisfaction was a secondary concern, while women had limited space to exercise mate choice. The mismatch between ancestral and modern conditions, with female choice being stronger in the present than in the past, causes anxiety in men about their ability to satisfy their partners, which is also manifested in their concerns about size.

  5. The Gray Matter Volume of the Amygdala Is Correlated with the Perception of Melodic Intervals: A Voxel-Based Morphometry Study

    NARCIS (Netherlands)

    Li, X.; Beuckelaer, A. De; Guo, J.; Ma, F.; Xu, M.; Liu, J.

    2014-01-01

    Music is not simply a series of organized pitches, rhythms, and timbres, it is capable of evoking emotions. In the present study, voxel-based morphometry (VBM) was employed to explore the neural basis that may link music to emotion. To do this, we identified the neuroanatomical correlates of the abi

  6. Lithological, grain-size and architectural trends in the holocene Rhine-Meuse delta-insights from 3D voxel models

    NARCIS (Netherlands)

    Stafleu, J.; Busschers, F.S.

    2014-01-01

    TNO Geological Survey of the Netherlands systematically produces 3D voxel models for answering subsurface related questions. The unique combination of vast amounts of borehole data and the voxelbased approach makes the models valuable new sources for exploring the Quaternary fluvial record. The late

  7. Lithological, grain-size and architectural trends in the holocene Rhine-Meuse delta-insights from 3D voxel models

    NARCIS (Netherlands)

    Stafleu, J.; Busschers, F.S.

    2014-01-01

    TNO Geological Survey of the Netherlands systematically produces 3D voxel models for answering subsurface related questions. The unique combination of vast amounts of borehole data and the voxelbased approach makes the models valuable new sources for exploring the Quaternary fluvial record. The late

  8. Size-fractionated production and bioavailability of dissolved organic matter

    DEFF Research Database (Denmark)

    Knudsen-Leerbeck, Helle; Bronk, Deborah A.; Markager, Stiig

    Production and bioavailability of dissolved organic matter was quantified on a time scale of two days from size fractions ranging from bacteria to zooplankton in the York River, Virginia. The goal was to find the main contributor to DOM. Batch incubation experiments were labeled with N15-ammonium...... was mainly in the phytoplankton size fraction, which on average contributed 62 % of total particulate nitrogen and 61 % of total particulate carbon. Up to 5 ± 0.4 μmol dissolved organic nitrogen L-1 and 33 ± 6.2 μmol dissolved organic carbon L-1 was produced during the incubation. Bioavailability...... of phytoplankton produced dissolved organic carbon was 12 ± 1 % and higher than in the presence of bacteria, microzooplankton, or copepods (7 ± 3 %). The pattern for bioavailability of dissolved organic nitrogen was less clear and ranged from 4 – 7 %. This study revealed that phytoplankton was the main contributor...

  9. The accuracy of linear measurements of maxillary and mandibular edentulous sites in cone-beam computed tomography images with different fields of view and voxel sizes under simulated clinical conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ganguly, Rumpa; Ramesh, Aruna; Pagni, Sarah [Tufts University School of Dental Medicine, Boston (United States)

    2016-06-15

    The objective of this study was to investigate the effect of varying resolutions of cone-beam computed tomography images on the accuracy of linear measurements of edentulous areas in human cadaver heads. Intact cadaver heads were used to simulate a clinical situation. Fiduciary markers were placed in the edentulous areas of 4 intact embalmed cadaver heads. The heads were scanned with two different CBCT units using a large field of view (13 cm×16 cm) and small field of view (5 cm×8 cm) at varying voxel sizes (0.3 mm, 0.2 mm, and 0.16 mm). The ground truth was established with digital caliper measurements. The imaging measurements were then compared with caliper measurements to determine accuracy. The Wilcoxon signed rank test revealed no statistically significant difference between the medians of the physical measurements obtained with calipers and the medians of the CBCT measurements. A comparison of accuracy among the different imaging protocols revealed no significant differences as determined by the Friedman test. The intraclass correlation coefficient was 0.961, indicating excellent reproducibility. Inter-observer variability was determined graphically with a Bland-Altman plot and by calculating the intraclass correlation coefficient. The Bland-Altman plot indicated very good reproducibility for smaller measurements but larger discrepancies with larger measurements. The CBCT-based linear measurements in the edentulous sites using different voxel sizes and FOVs are accurate compared with the direct caliper measurements of these sites. Higher resolution CBCT images with smaller voxel size did not result in greater accuracy of the linear measurements.

  10. Investigation of Nonuniform Dose Voxel Geometry in Monte Carlo Calculations.

    Science.gov (United States)

    Yuan, Jiankui; Chen, Quan; Brindle, James; Zheng, Yiran; Lo, Simon; Sohn, Jason; Wessels, Barry

    2015-08-01

    The purpose of this work is to investigate the efficacy of using multi-resolution nonuniform dose voxel geometry in Monte Carlo (MC) simulations. An in-house MC code based on the dose planning method MC code was developed in C++ to accommodate the nonuniform dose voxel geometry package since general purpose MC codes use their own coupled geometry packages. We devised the package in a manner that the entire calculation volume was first divided into a coarse mesh and then the coarse mesh was subdivided into nonuniform voxels with variable voxel sizes based on density difference. We name this approach as multi-resolution subdivision (MRS). It generates larger voxels in small density gradient regions and smaller voxels in large density gradient regions. To take into account the large dose gradients due to the beam penumbra, the nonuniform voxels can be further split using ray tracing starting from the beam edges. The accuracy of the implementation of the algorithm was verified by comparing with the data published by Rogers and Mohan. The discrepancy was found to be 1% to 2%, with a maximum of 3% at the interfaces. Two clinical cases were used to investigate the efficacy of nonuniform voxel geometry in the MC code. Applying our MRS approach, we started with the initial voxel size of 5 × 5 × 3 mm(3), which was further divided into smaller voxels. The smallest voxel size was 1.25 × 1.25 × 3 mm(3). We found that the simulation time per history for the nonuniform voxels is about 30% to 40% faster than the uniform fine voxels (1.25 × 1.25 × 3 mm(3)) while maintaining similar accuracy.

  11. Voxel-based morphometry MRI study of gray matter change in patients with Parkinson's disease%帕金森病患者脑灰质变化的VBM-MRI研究

    Institute of Scientific and Technical Information of China (English)

    郭黎; 史长征; 胡艳; 彭子文; 杨柳; 徐安定

    2012-01-01

    Objective To delineate the gray matter changes of Parkinson's disease(PD) patients applied by voxel-based morphometry method (VBM) of magnetic resonance imaging (MRI). Methods of the regional gray matter volume was studied using voxel-based morphometry in 28 PD patients including 14 early stage PD (EPD) and 14 late stage PD (LPD) and 32 age- and education-matched controls. Results Compared with normal controls, PD patients had significant reductions of the gray matter volume in the frontal lobe (bilateral superior frontal gyrus, left inferior frontal gyrus), bilateral temporal lobes (superior temporal gyrus, middle temporal gyrus), right cingulated gyrus, right thalamus, bilateral caudate nucleus, and left inferior parietal lobe . Compared with EPD, LPD had significant reductions of gray matter volume in the frontal lobe(bilateral superior frontal gyrus, right inferior frontal gyrus, right orbitofrontal cortex and bilateral medial anterior frontal lobe), temporal lobe (right superior temporal gyrus, left middle temporal gyms),right parahippocampal gyrus, right caudate nucleus and right hypothalamus. Conclusions PD patients have significant reductions of the gray matter volume mainly in the frontal lobe, temporal lobe, right cingulate gyrus and subcor-tical gray matter. With the progression of PD, the reductions of gray matter volume increase in these regions and expend to the limbic system.%目的 应用核磁共振的基于体素形态学(voxel-based morphometry method of magnetic resonance imaging.VBM-MRI)技术,研究帕金森病(Parkinson disease,PD)患者大脑灰质变化的状况.方法 28例PD组与年龄、受教育年限相匹配32例健康对照组的VBM-MRI图像数据进行比较,PD组中,早期PD组(early Parkinson disease.EPD,n=14)与晚期PD组((late Parkinson disease.LPD,n=14)的VBM-MRI图像数据进行比较.结果 与健康对照组比较.VBM-MRI显示PD组患者存在下列脑区灰质体积减少:额叶(双侧额上回、左额下回)、双

  12. Multistep Lattice-Voxel method utilizing lattice function for Monte-Carlo treatment planning with pixel based voxel model.

    Science.gov (United States)

    Kumada, H; Saito, K; Nakamura, T; Sakae, T; Sakurai, H; Matsumura, A; Ono, K

    2011-12-01

    Treatment planning for boron neutron capture therapy generally utilizes Monte-Carlo methods for calculation of the dose distribution. The new treatment planning system JCDS-FX employs the multi-purpose Monte-Carlo code PHITS to calculate the dose distribution. JCDS-FX allows to build a precise voxel model consisting of pixel based voxel cells in the scale of 0.4×0.4×2.0 mm(3) voxel in order to perform high-accuracy dose estimation, e.g. for the purpose of calculating the dose distribution in a human body. However, the miniaturization of the voxel size increases calculation time considerably. The aim of this study is to investigate sophisticated modeling methods which can perform Monte-Carlo calculations for human geometry efficiently. Thus, we devised a new voxel modeling method "Multistep Lattice-Voxel method," which can configure a voxel model that combines different voxel sizes by utilizing the lattice function over and over. To verify the performance of the calculation with the modeling method, several calculations for human geometry were carried out. The results demonstrated that the Multistep Lattice-Voxel method enabled the precise voxel model to reduce calculation time substantially while keeping the high-accuracy of dose estimation.

  13. Size matters: abundance matching, galaxy sizes, and the Tully-Fisher relation in EAGLE

    CERN Document Server

    Ferrero, Ismael; Abadi, Mario G; Sales, Laura V; Bower, Richard G; Crain, Robert A; Frenk, Carlos S; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2016-01-01

    The Tully-Fisher relation (TFR) links the stellar mass of a disk galaxy, $M_{\\rm str}$, to its rotation speed: it is well approximated by a power law, shows little scatter, and evolves weakly with redshift. The relation has been interpreted as reflecting the mass-velocity scaling ($M\\propto V^3$) of dark matter halos, but this interpretation has been called into question by abundance-matching (AM) models, which predict the galaxy-halo mass relation to be non-monotonic and rapidy evolving. We study the TFR of luminous spirals and its relation to AM using the EAGLE set of $\\Lambda$CDM cosmological simulations. Matching both relations requires disk sizes to satisfy constraints given by the concentration of halos and their response to galaxy assembly. EAGLE galaxies approximately match these constraints and show a tight mass-velocity scaling that compares favourably with the observed TFR. The TFR is degenerate to changes in galaxy formation efficiency and the mass-size relation; simulations that fail to match the...

  14. Does Stake Size matter for Cooperation and Punishment?

    OpenAIRE

    2006-01-01

    The effects of stake size on cooperation and punishment are investigated using a public goods experiment. We find that an increase in stake size does neither significantly affect cooperation nor, interestingly, the level of punishment.

  15. Size matters : Pitch dimensions constrain interactive team behaviour in soccer

    NARCIS (Netherlands)

    Frencken, Wouter; Van der Plaats, Jorrit; Visscher, Chris; Lemmink, Koen

    2013-01-01

    Pitch size varies in official soccer matches and differently sized pitches are adopted for tactical purposes in small-sided training games. Since interactive team behaviour emerges under constraints, the authors evaluate the effect of pitch size (task) manipulations on interactive team behaviour in

  16. Voxel-based morphometry and fMRI revealed differences in brain gray matter in breastfed and milk formula–fed children

    Science.gov (United States)

    Background and Purpose: Infant diets may have significant impact on brain development in children. The aim of this study was to evaluate brain grey matter structure and function in 8-year-old children who were predominantly breastfed (BF) or fed cow’s milk formula (MF) as infants. Materials and Me...

  17. White matter abnormalities at a regional and voxel level in focal and generalized epilepsy : A systematic review and meta-analysis

    NARCIS (Netherlands)

    Slinger, Geertruida; Sinke, Michel R T; Braun, Kees P J|info:eu-repo/dai/nl/207237239; Otte, Willem M.|info:eu-repo/dai/nl/168455706

    2016-01-01

    Objective Since the introduction of diffusion tensor imaging, white matter abnormalities in epilepsy have been studied extensively. However, the affected areas reported, the extent of abnormalities and the association with relevant clinical parameters are highly variable. We aimed to obtain a more

  18. Strategic Role of Frontal White Matter Tracts in Vascular Cognitive Impairment: A Voxel-Based Lesion-Symptom Mapping Study in CADASIL

    Science.gov (United States)

    Duering, Marco; Zieren, Nikola; Herve, Dominique; Jouvent, Eric; Reyes, Sonia; Peters, Nils; Pachai, Chahin; Opherk, Christian; Chabriat, Hugues; Dichgans, Martin

    2011-01-01

    Cerebral small vessel disease is the most common cause of vascular cognitive impairment. It typically manifests with lacunar infarcts and ischaemic white matter lesions. However, little is known about how these lesions relate to the cognitive symptoms. Previous studies have found a poor correlation between the burden of ischaemic lesions and…

  19. Bacterial utilization of size-fractionated dissolved organic matter

    Digital Repository Service at National Institute of Oceanography (India)

    Khodse, V.B.; Bhosle, N.B.

    Dissolved organic matter (DOM) is an important source of organic carbon for sustaining the growth of heterotrophic bacteria. The bacterial utilization of high-molecular-weight (HMW; greater than 30 kDa to 0.22 mu m) and low-molecular-weight (LMW...

  20. When the Single Matters more than the Group (II): Addressing the Problem of High False Positive Rates in Single Case Voxel Based Morphometry Using Non-parametric Statistics.

    Science.gov (United States)

    Scarpazza, Cristina; Nichols, Thomas E; Seramondi, Donato; Maumet, Camille; Sartori, Giuseppe; Mechelli, Andrea

    2016-01-01

    In recent years, an increasing number of studies have used Voxel Based Morphometry (VBM) to compare a single patient with a psychiatric or neurological condition of interest against a group of healthy controls. However, the validity of this approach critically relies on the assumption that the single patient is drawn from a hypothetical population with a normal distribution and variance equal to that of the control group. In a previous investigation, we demonstrated that family-wise false positive error rate (i.e., the proportion of statistical comparisons yielding at least one false positive) in single case VBM are much higher than expected (Scarpazza et al., 2013). Here, we examine whether the use of non-parametric statistics, which does not rely on the assumptions of normal distribution and equal variance, would enable the investigation of single subjects with good control of false positive risk. We empirically estimated false positive rates (FPRs) in single case non-parametric VBM, by performing 400 statistical comparisons between a single disease-free individual and a group of 100 disease-free controls. The impact of smoothing (4, 8, and 12 mm) and type of pre-processing (Modulated, Unmodulated) was also examined, as these factors have been found to influence FPRs in previous investigations using parametric statistics. The 400 statistical comparisons were repeated using two independent, freely available data sets in order to maximize the generalizability of the results. We found that the family-wise error rate was 5% for increases and 3.6% for decreases in one data set; and 5.6% for increases and 6.3% for decreases in the other data set (5% nominal). Further, these results were not dependent on the level of smoothing and modulation. Therefore, the present study provides empirical evidence that single case VBM studies with non-parametric statistics are not susceptible to high false positive rates. The critical implication of this finding is that VBM can be used

  1. 海洛因依赖者脑灰质体积的VBM研究%Voxel Based Morphometry Study of Cerebral Gray Matter Volume in Patients With Heroin Dependence

    Institute of Scientific and Technical Information of China (English)

    朱佳; 王亚蓉; 李强; 李玮; 杨伟川; 吴宁; 常海峰; 王玮

    2012-01-01

    目的 探讨海洛因依赖对大脑灰质结构的作用,分析吸食海洛因总时间、吸食海洛因总量、每日吸食海洛因量等因素对脑灰质体积产生的影响.资料与方法 采用MRI对17例海洛因依赖者和15名健康受试者行3D 结构像扫描,所得数据用基于体素的形态学分析(voxel based morphometry,VBM)方法分析脑灰质体积,并比较两组之间的体积差异;分析脑灰质体积与吸食海洛因总时间、吸食海洛因总量、每日吸食海洛因量之间的相关关系.结果 与健康被试者相比,海洛因依赖者右侧眶额回、中央前回、左侧岛叶、扣带回、枕叶舌回灰质体积减少(P<0.005);控制年龄、受教育程度、每日吸烟量后,脑灰质体积变化与使用海洛因总时间、海洛因总量、每日吸食海洛因量之间无显著相关关系.结论 长期吸食海洛因导致脑灰质结构损害,主要涉及认知控制、情感、视觉控制等相关脑区.%Objective To investigate the effect of heroin on cerebral gray structure in patients with heroin dependence. Materials and Methods Seventeen heroin dependent patients and 15 normal volunteers performed 3D structural MR examination. The cerebral grey matter volume was measured by voxel based morphometry (VBM). The differences of cerebral grey matter volume between two groups were compared by two sample t-test. Partial correlation analysis was to measure the relativity between grey matter volume and the duration of heroin use, the total dose of heroin use as well as the everyday dose of heroin. Results Compared with the control group, the cerebral gray matter volume in heroin dependent group had a significant decrease (P <0. 005) in the right orbital frontal gyrus, right precentral gyrus, left insular, left cingulate gyrus and left lingual gyrus. Partial correlation analysis, which controlled for age, education and nicotine use factors, showed that the duration of heroin use, the total dose of

  2. Public decisions on animal species : does body size matter?

    NARCIS (Netherlands)

    Knegtering, Edo; van der Windt, Henny J.; Schoot Uiterkamp, Anton J. M.

    Systematic knowledge about factors affecting the willingness of societies to conserve biodiversity is still scarce. This study investigates the role of body size in national decisions on wild animal species by analysing the average body sizes of the animal species subject to species-specific

  3. Mass size distributions and size resolved chemical composition of fine particulate matter at the Pittsburgh supersite

    Science.gov (United States)

    Cabada, Juan C.; Rees, Sarah; Takahama, Satoshi; Khlystov, Andrey; Pandis, Spyros N.; Davidson, Cliff I.; Robinson, Allen L.

    Size-resolved aerosol mass and chemical composition were measured during the Pittsburgh Air Quality Study. Daily samples were collected for 12 months from July 2001 to June 2002. Micro-orifice uniform deposit impactors (MOUDIs) were used to collect aerosol samples of fine particulate matter smaller than 10 μm. Measurements of PM 0.056, PM 0.10, PM 0.18, PM 0.32, PM 0.56, PM 1.0, PM 1.8 and PM 2.5 with the MOUDI are available for the full study period. Seasonal variations in the concentrations are observed for all size cuts. Higher concentrations are observed during the summer and lower during the winter. Comparison between the PM 2.5 measurements by the MOUDI and other integrated PM samplers reveals good agreement. Good correlation is observed for PM 10 between the MOUDI and an integrated sampler but the MOUDI underestimates PM 10 by 20%. Bouncing of particles from higher stages of the MOUDI (>PM 2.5) is not a major problem because of the low concentrations of coarse particles in the area. The main cause of coarse particle losses appears to be losses to the wall of the MOUDI. Samples were collected on aluminum foils for analysis of carbonaceous material and on Teflon filters for analysis of particle mass and inorganic anions and cations. Daily samples were analyzed during the summer (July 2001) and the winter intensives (January 2002). During the summer around 50% of the organic material is lost from the aluminum foils as compared to a filter-based sampler. These losses are due to volatilization and bounce-off from the MOUDI stages. High nitrate losses from the MOUDI are also observed during the summer (above 70%). Good agreement between the gravimetrically determined mass and the sum of the masses of the individual compounds is obtained, if the lost mass from organics and the aerosol water content are included for the summer. For the winter no significant losses of material are detected and there exists reasonable agreement between the gravimetrical mass and the

  4. Pacific carbon cycling constrained by organic matter size, age and composition relationships

    Science.gov (United States)

    Walker, Brett D.; Beaupré, Steven R.; Guilderson, Thomas P.; McCarthy, Matthew D.; Druffel, Ellen R. M.

    2016-12-01

    Marine organic matter is one of Earth’s largest actively cycling reservoirs of organic carbon and nitrogen. The processes controlling organic matter production and removal are important for carbon and nitrogen biogeochemical cycles, which regulate climate. However, the many possible cycling mechanisms have hindered our ability to quantify marine organic matter transformation, degradation and turnover rates. Here we analyse existing and new measurements of the carbon:nitrogen ratio and radiocarbon age of organic matter spanning sizes from large particulate organic matter to small dissolved organic molecules. We find that organic matter size is negatively correlated with radiocarbon age and carbon:nitrogen ratios in coastal, surface and deep waters of the Pacific Ocean. Our measurements suggest that organic matter is increasingly chemically degraded as it decreases in size, and that small particles and molecules persist in the ocean longer than their larger counterparts. Based on these correlations, we estimate the production rates of small, biologically recalcitrant dissolved organic matter molecules at 0.11-0.14 Gt of carbon and about 0.005 Gt of nitrogen per year in the deep ocean. Our results suggest that the preferential remineralization of large over small particles and molecules is a key process governing organic matter cycling and deep ocean carbon storage.

  5. Effect of Pot Size on Various Characteristics Related to Photosynthetic Matter Production in Soybean Plants

    OpenAIRE

    Minobu Kasai; Keisuke Koide; Yuya Ichikawa

    2012-01-01

    Despite the wide uses of potted plants, information on how pot size affects plant photosynthetic matter production is still considerably limited. This study investigated with soybean plants how transplantation into larger pots affects various characteristics related to photosynthetic matter production. The transplantation was analyzed to increase leaf photosynthetic rate, transpiration rate, and stomatal conductance without affecting significantly leaf intercellular CO2 concentration, implica...

  6. Silver nanoparticle toxicity in Drosophila: size does matter

    Directory of Open Access Journals (Sweden)

    Deborah J Gorth

    2011-02-01

    Full Text Available Deborah J Gorth1, David M Rand2, Thomas J Webster11School of Engineering, 2Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, USABackground: Consumer nanotechnology is a growing industry. Silver nanoparticles are the most common nanomaterial added to commercially available products, so understanding the influence that size has on toxicity is integral to the safe use of these new products. This study examined the influence of silver particle size on Drosophila egg development by comparing the toxicity of both nanoscale and conventional-sized silver particles.Methods: The toxicity assays were conducted by exposing Drosophila eggs to particle concentrations ranging from 10 ppm to 100 ppm of silver. Size, chemistry, and agglomeration of the silver particles were evaluated using transmission electron microscopy, X-ray photoelectron spectroscopy, and dynamic light scattering.Results: This analysis confirmed individual silver particle sizes in the ranges of 20–30 nm, 100 nm, and 500–1200 nm, with similar chemistry. Dynamic light scattering and transmission electron microscope data also indicated agglomeration in water, with the transmission electron microscopic images showing individual particles in the correct size range, but the dynamic light scattering z-average sizes of the silver nanoparticles were 782 ± 379 nm for the 20–30 nm silver nanoparticles, 693 ± 114 nm for the 100 nm silver nanoparticles, and 508 ± 32 nm for the 500–1200 nm silver particles. Most importantly, here we show significantly more Drosophila egg toxicity when exposed to larger, nonnanometer silver particles. Upon exposure to silver nanoparticles sized 20–30 nm, Drosophila eggs did not exhibit a statistically significant (P < 0.05 decrease in their likelihood to pupate, but eggs exposed to larger silver particles (500–1200 nm were 91% ± 18% less likely to pupate. Exposure to silver nanoparticles reduced the percentage of pupae able

  7. Archaeological Soybean (Glycine max) in East Asia: Does Size Matter?

    Science.gov (United States)

    Lee, Gyoung-Ah; Crawford, Gary W.; Liu, Li; Sasaki, Yuka; Chen, Xuexiang

    2011-01-01

    The recently acquired archaeological record for soybean from Japan, China and Korea is shedding light on the context in which this important economic plant became associated with people and was domesticated. This paper examines archaeological (charred) soybean seed size variation to determine what insight can be gained from a comprehensive comparison of 949 specimens from 22 sites. Seed length alone appears to represent seed size change through time, although the length×width×thickness product has the potential to provide better size change resolution. A widespread early association of small seeded soybean is as old as 9000–8600 cal BP in northern China and 7000 cal BP in Japan. Direct AMS radiocarbon dates on charred soybean seeds indicate selection resulted in large seed sizes in Japan by 5000 cal BP (Middle Jomon) and in Korea by 3000 cal BP (Early Mumun). Soybean seeds recovered in China from the Shang through Han periods are similar in length to the large Korean and Japanese specimens, but the overall size of the large Middle and Late Jomon, Early Mumun through Three Kingdom seeds is significantly larger than any of the Chinese specimens. The archaeological record appears to disconfirm the hypothesis of a single domestication of soybean and supports the view informed by recent phyologenetic research that soybean was domesticated in several locations in East Asia. PMID:22073186

  8. Does Size Matter? The Multipolar International Landscape of Nanoscience.

    Science.gov (United States)

    Levin, Luciano; Jensen, Pablo; Kreimer, Pablo

    2016-01-01

    How do different countries tackle nanoscience research? Are all countries similar except for a trivial size effect, as science is often assumed to be universal? Or does size dictate large differences, as large countries are able to develop activities in all directions of research, while small countries have to specialize in some specific niches? Alternatively, is size irrelevant, as all countries have followed different historical paths, leading to different patterns of specialisation? Here, we develop an original method that uses a bottom-up definition of scientific subfields to map the international structure of any scientific field. Our analysis shows that nanoscience research does not show a universal pattern of specialisation, homothetic of that of a single global leader (e.g., the United States). Instead, we find a multipolar world, with four main ways of doing nanosciences.

  9. Mosquito consumption by insectivorous bats: does size matter?

    Directory of Open Access Journals (Sweden)

    Leroy Gonsalves

    Full Text Available Insectivorous bats have often been touted as biological control for mosquito populations. However, mosquitoes generally represent only a small proportion of bat diet. Given the small size of mosquitoes, restrictions imposed on prey detectability by low frequency echolocation, and variable field metabolic rates (FMR, mosquitoes may not be available to or profitable for all bats. This study investigated whether consumption of mosquitoes was influenced by bat size, which is negatively correlated with echolocation frequency but positively correlated with bat FMR. To assess this, we investigated diets of five eastern Australian bat species (Vespadelus vulturnus Thomas, V. pumilus Gray, Miniopterus australis Tomes, Nyctophilus gouldi Tomes and Chalinolobus gouldii Gray ranging in size from 4-14 g in coastal forest, using molecular analysis of fecal DNA. Abundances of potential mosquito and non-mosquito prey were concurrently measured to provide data on relative prey abundance. Aedes vigilax was locally the most abundant mosquito species, while Lepidoptera the most abundant insect order. A diverse range of prey was detected in bat feces, although members of Lepidoptera dominated, reflecting relative abundance at trap sites. Consumption of mosquitoes was restricted to V. vulturnus and V. pumilus, two smaller sized bats (4 and 4.5 g. Although mosquitoes were not commonly detected in feces of V. pumilus, they were present in feces of 55 % of V. vulturnus individuals. To meet nightly FMR requirements, Vespadelus spp. would need to consume ~600-660 mosquitoes on a mosquito-only diet, or ~160-180 similar sized moths on a moth-only diet. Lower relative profitability of mosquitoes may provide an explanation for the low level of mosquito consumption among these bats and the absence of mosquitoes in feces of larger bats. Smaller sized bats, especially V. vulturnus, are likely to be those most sensitive to reductions in mosquito abundance and should be monitored

  10. Wildfire selectivity for land cover type: does size matter?

    Science.gov (United States)

    Barros, Ana M G; Pereira, José M C

    2014-01-01

    Previous research has shown that fires burn certain land cover types disproportionally to their abundance. We used quantile regression to study land cover proneness to fire as a function of fire size, under the hypothesis that they are inversely related, for all land cover types. Using five years of fire perimeters, we estimated conditional quantile functions for lower (avoidance) and upper (preference) quantiles of fire selectivity for five land cover types - annual crops, evergreen oak woodlands, eucalypt forests, pine forests and shrublands. The slope of significant regression quantiles describes the rate of change in fire selectivity (avoidance or preference) as a function of fire size. We used Monte-Carlo methods to randomly permutate fires in order to obtain a distribution of fire selectivity due to chance. This distribution was used to test the null hypotheses that 1) mean fire selectivity does not differ from that obtained by randomly relocating observed fire perimeters; 2) that land cover proneness to fire does not vary with fire size. Our results show that land cover proneness to fire is higher for shrublands and pine forests than for annual crops and evergreen oak woodlands. As fire size increases, selectivity decreases for all land cover types tested. Moreover, the rate of change in selectivity with fire size is higher for preference than for avoidance. Comparison between observed and randomized data led us to reject both null hypotheses tested ([Formula: see text] = 0.05) and to conclude it is very unlikely the observed values of fire selectivity and change in selectivity with fire size are due to chance.

  11. Patenting activities and firm performance : Does firm size matter?

    NARCIS (Netherlands)

    Andries, P.; Faems, D.L.M.

    2013-01-01

    Whereas prior research has provided valuable insights into the willingness of small and medium-sized enterprises (SMEs) and large firms to engage in patenting, a comparison of the performance implications of patenting activities across small and large firms is still lacking. This gap is important be

  12. Does size matter? Animal units and animal unit months

    Science.gov (United States)

    Lamar Smith; Joe Hicks; Scott Lusk; Mike Hemmovich; Shane Green; Sarah McCord; Mike Pellant; John Mitchell; Judith Dyess; Jim Sprinkle; Amanda Gearhart; Sherm Karl; Mike Hannemann; Ken Spaeth; Jason Karl; Matt Reeves; Dave Pyke; Jordan Spaak; Andrew Brischke; Del Despain; Matt Phillippi; Dave Weixelmann; Alan Bass; Jessie Page; Lori Metz; David Toledo; Emily Kachergis

    2017-01-01

    The concepts of animal units, animal unit months, and animal unit equivalents have long been used as standards for range management planning, estimating stocking rates, reporting actual use, assessing grazing fees, ranch appraisal, and other purposes. Increasing size of cattle on rangelands has led some to suggest that the definition of animal units and animal unit...

  13. Hypofractionated Whole-Breast Radiation Therapy: Does Breast Size Matter?

    Energy Technology Data Exchange (ETDEWEB)

    Hannan, Raquibul, E-mail: Raquibul.Hannan@gmail.com [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas (United States); Thompson, Reid F.; Chen Yu; Bernstein, Karen; Kabarriti, Rafi; Skinner, William [Department of Radiation Oncology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York (United States); Chen, Chin C. [Department of Radiation Oncology, Columbia University Medical Center, New York, New York (United States); Landau, Evan; Miller, Ekeni; Spierer, Marnee; Hong, Linda; Kalnicki, Shalom [Department of Radiation Oncology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York (United States)

    2012-11-15

    Purpose: To evaluate the effects of breast size on dose-volume histogram parameters and clinical toxicity in whole-breast hypofractionated radiation therapy using intensity modulated radiation therapy (IMRT). Materials and Methods: In this retrospective study, all patients undergoing breast-conserving therapy between 2005 and 2009 were screened, and qualifying consecutive patients were included in 1 of 2 cohorts: large-breasted patients (chest wall separation >25 cm or planning target volume [PTV] >1500 cm{sub 3}) (n=97) and small-breasted patients (chest wall separation <25 cm and PTV <1500 cm{sub 3}) (n=32). All patients were treated prone or supine with hypofractionated IMRT to the whole breast (42.4 Gy in 16 fractions) followed by a boost dose (9.6 Gy in 4 fractions). Dosimetric and clinical toxicity data were collected and analyzed using the R statistical package (version 2.12). Results: The mean PTV V95 (percentage of volume receiving >= 95% of prescribed dose) was 90.18% and the mean V105 percentage of volume receiving >= 105% of prescribed dose was 3.55% with no dose greater than 107%. PTV dose was independent of breast size, whereas heart dose and maximum point dose to skin correlated with increasing breast size. Lung dose was markedly decreased in prone compared with supine treatments. Radiation Therapy Oncology Group grade 0, 1, and 2 skin toxicities were noted acutely in 6%, 69%, and 25% of patients, respectively, and at later follow-up (>3 months) in 43%, 57%, and 0% of patients, respectively. Large breast size contributed to increased acute grade 2 toxicity (28% vs 12%, P=.008). Conclusions: Adequate PTV coverage with acceptable hot spots and excellent sparing of organs at risk was achieved by use of IMRT regardless of treatment position and breast size. Although increasing breast size leads to increased heart dose and maximum skin dose, heart dose remained within our institutional constraints and the incidence of overall skin toxicity was comparable

  14. Yoga Meditation Practitioners Exhibit Greater Gray Matter Volume and Fewer Reported Cognitive Failures: Results of a Preliminary Voxel-Based Morphometric Analysis

    Directory of Open Access Journals (Sweden)

    Brett Froeliger

    2012-01-01

    Full Text Available Hatha yoga techniques, including physical postures (asanas, breathing exercises (pranayama, and meditation, involve the practice of mindfulness. In turn, yoga meditation practices may induce the state of mindfulness, which, when evoked recurrently through repeated practice, may accrue into trait or dispositional mindfulness. Putatively, these changes may be mediated by experience-dependent neuroplastic changes. Though prior studies have identified differences in gray matter volume (GMV between long-term mindfulness practitioners and controls, no studies to date have reported on whether yoga meditation is associated with GMV differences. The present study investigated GMV differences between yoga meditation practitioners (YMP and a matched control group (CG. The YMP group exhibited greater GM volume in frontal, limbic, temporal, occipital, and cerebellar regions; whereas the CG had no greater regional greater GMV. In addition, the YMP group reported significantly fewer cognitive failures on the Cognitive Failures Questionnaire (CFQ, the magnitude of which was positively correlated with GMV in numerous regions identified in the primary analysis. Lastly, GMV was positively correlated with the duration of yoga practice. Results from this preliminary study suggest that hatha yoga practice may be associated with the promotion of neuroplastic changes in executive brain systems, which may confer therapeutic benefits that accrue with repeated practice.

  15. Host-parasite coevolution: why changing population size matters.

    Science.gov (United States)

    Papkou, Andrei; Gokhale, Chaitanya S; Traulsen, Arne; Schulenburg, Hinrich

    2016-08-01

    Host-parasite coevolution is widely assumed to have a major influence on biological evolution, especially as these interactions impose high selective pressure on the reciprocally interacting antagonists. The exact nature of the underlying dynamics is yet under debate and may be determined by recurrent selective sweeps (i.e., arms race dynamics), negative frequency-dependent selection (i.e., Red Queen dynamics), or a combination thereof. These interactions are often associated with reciprocally induced changes in population size, which, in turn, should have a strong impact on co-adaptation processes, yet are neglected in most current work on the topic. Here, we discuss potential consequences of temporal variations in population size on host-parasite coevolution. The limited empirical data available and the current theoretical literature in this field highlight that the consideration of such interaction-dependent population size changes is likely key for the full understanding of the coevolutionary dynamics, and, thus, a more realistic view on the complex nature of species interactions.

  16. UTILIZATION OF QUALITY TOOLS: DOES SECTOR AND SIZE MATTER?

    Directory of Open Access Journals (Sweden)

    Luis Fonseca

    2015-12-01

    Full Text Available This research focuses on the influence of company sector and size on the level of utilization of Basic and Advanced Quality Tools. The paper starts with a literature review and then presents the methodology used for the survey. Based on the responses from 202 managers of Portuguese ISO 9001:2008 Quality Management System certified organizations, statistical tests were performed. Results show, with 95% confidence level, that industry and services have a similar proportion of use of Basic and Advanced Quality Tools. Concerning size, bigger companies show a higher trend to use Advanced Quality Tools than smaller ones. For Basic Quality Tools, there was no statistical significant difference at a 95% confidence level for different company sizes. The three basic Quality tools with higher utilization were Check sheets, Flow charts and Histograms (for Services or Control Charts/ (for Industry, however 22% of the surveyed organizations reported not using Basic Quality Tools, which highlights a major improvement opportunity for these companies. Additional studies addressing motivations, benefits and barriers for Quality Tools application should be undertaken for further validation and understanding of these results.

  17. (Sample) Size Matters: Defining Error in Planktic Foraminiferal Isotope Measurement

    Science.gov (United States)

    Lowery, C.; Fraass, A. J.

    2015-12-01

    Planktic foraminifera have been used as carriers of stable isotopic signals since the pioneering work of Urey and Emiliani. In those heady days, instrumental limitations required hundreds of individual foraminiferal tests to return a usable value. This had the fortunate side-effect of smoothing any seasonal to decadal changes within the planktic foram population, which generally turns over monthly, removing that potential noise from each sample. With the advent of more sensitive mass spectrometers, smaller sample sizes have now become standard. This has been a tremendous advantage, allowing longer time series with the same investment of time and energy. Unfortunately, the use of smaller numbers of individuals to generate a data point has lessened the amount of time averaging in the isotopic analysis and decreased precision in paleoceanographic datasets. With fewer individuals per sample, the differences between individual specimens will result in larger variation, and therefore error, and less precise values for each sample. Unfortunately, most workers (the authors included) do not make a habit of reporting the error associated with their sample size. We have created an open-source model in R to quantify the effect of sample sizes under various realistic and highly modifiable parameters (calcification depth, diagenesis in a subset of the population, improper identification, vital effects, mass, etc.). For example, a sample in which only 1 in 10 specimens is diagenetically altered can be off by >0.3‰ δ18O VPDB or ~1°C. Additionally, and perhaps more importantly, we show that under unrealistically ideal conditions (perfect preservation, etc.) it takes ~5 individuals from the mixed-layer to achieve an error of less than 0.1‰. Including just the unavoidable vital effects inflates that number to ~10 individuals to achieve ~0.1‰. Combining these errors with the typical machine error inherent in mass spectrometers make this a vital consideration moving forward.

  18. Interfacial water thickness at inorganic nanoconstructs and biomolecules: Size matters

    Energy Technology Data Exchange (ETDEWEB)

    Cardellini, Annalisa; Fasano, Matteo; Chiavazzo, Eliodoro; Asinari, Pietro, E-mail: pietro.asinari@polito.it

    2016-04-29

    Water molecules in the proximity of solid nanostructures influence both the overall properties of liquid and the structure and functionality of solid particles. The study of water dynamics at solid–liquid interfaces has strong implications in energy, environmental and biomedical fields. This article focuses on the hydration layer properties in the proximity of Carbon Nanotubes (CNTs) and biomolecules (proteins, polypeptides and amino acids). Here we show a quantitative relation between the solid surface extension and the characteristic length of water nanolayer (δ), which is confined at solid–liquid interfaces. Specifically, the size dependence is attributed to the limited superposition of nonbonded interactions in case of small molecules. These results may facilitate the design of novel energy or biomedical colloidal nanosuspensions, and a more fundamental understanding of biomolecular processes influenced by nanoscale water dynamics. - Highlights: • Properties of the water hydration layer are investigated. • New relation between extension of solid size and hydration layer established. • Possible impact on rational design of nanosuspensions.

  19. Why herd size matters - mitigating the effects of livestock crashes.

    Directory of Open Access Journals (Sweden)

    Marius Warg Næss

    Full Text Available Analysing the effect of pastoral risk management strategies provides insights into a system of subsistence that have persevered in marginal areas for hundreds to thousands of years and may shed light into the future of around 200 million households in the face of climate change. This study investigated the efficiency of herd accumulation as a buffer strategy by analysing changes in livestock holdings during an environmental crisis in the Saami reindeer husbandry in Norway. We found a positive relationship between: (1 pre- and post-collapse herd size; and (2 pre-collapse herd size and the number of animals lost during the collapse, indicating that herd accumulation is an effective but costly strategy. Policies that fail to incorporate the risk-beneficial aspect of herd accumulation will have a limited effect and may indeed fail entirely. In the context of climate change, official policies that incorporate pastoral risk management strategies may be the only solution for ensuring their continued existence.

  20. Cost-effective unilateral climate policy design: Size Matters

    Energy Technology Data Exchange (ETDEWEB)

    Boehringer, Christoph; Fischer, Carolyn; Rosendahl, Knut Einar

    2011-07-01

    Given the bleak prospects for a global agreement on mitigating climate change, pressure for unilateral abatement is increasing. A major challenge is emissions leakage. Border carbon adjustments and output-based allocation of emissions allowances can increase effectiveness of unilateral action but introduce distortions of their own. We assess antileakage measures as a function of abatement coalition size. We first develop a partial equilibrium analytical framework to see how these instruments affect emissions within and outside the coalition. We then employ a computable general equilibrium model of international trade and energy use to assess the strategies as the coalition grows. We find that full border adjustments rank first in global cost-effectiveness, followed by import tariffs and output-based rebates. The differences across measures and their overall appeal decline as the abatement coalition grows. In terms of cost, the coalition countries prefer border carbon adjustments; countries outside the coalition prefer output-based rebates.(Author)

  1. [Clinical risk management in german hospitals - does size really matter?].

    Science.gov (United States)

    Bohnet-Joschko, S; Jandeck, L M; Zippel, C; Andersen, M; Krummenauer, F

    2011-06-01

    In the last years, German hospitals have implemented different measures to increase patient safety. Special importance has been attached to near miss reporting systems (critical incident reporting system, CIRS) as instruments for risk identification in health care, instruments that promise high potential for organisational learning. To gain insight into the current status of critical incident reporting systems and other instruments for clinical risk management, a survey among 341 hospitals was carried out in 2009. Questions covered a process of six steps: from risk strategy to methods for risk identification, to risk analysis and risk assessment, to risk controlling and risk monitoring. Structured telephone interviews were conducted with 341 German hospitals, featuring in their statutory quality reports certain predefined key terms that indicated the concluded or planned implementation of clinical risk management. The main objective of those interviews was to check the relation between status/organisation of self-reported risk management and both operator (private, public, NPO) and size of hospital. The implementation of near miss reporting systems (CIRS) in German hospitals has been constantly rising since 2004: in 2009, 54 % of the interviewed hospitals reported an implemented CIRS; of these, 72 % reported the system to be hospital-wide. An association between CIRS and private, public or NPO-operator could not be detected (Fisher p = 1.000); however, the degree of CIRS implementation was significantly increasing with the size of the hospital, i.e., the number of beds (Fisher p = 0.008): only 38 % of the hospitals with less than 100 beds reported CIRS implementation against 52 % of those between 100 to 500 beds, and 67 % of those with more than 500 beds. While 62 % of the hospitals interviewed reported the maintenance of a risk management committee, only 14 % reported the implementation of risk analysing techniques. As to clinical risk

  2. A voxel-based morphometric analysis of brain gray matter in online game addicts%网络游戏成瘾患者基于体素的脑灰质结构研究

    Institute of Scientific and Technical Information of China (English)

    翁传波; 钱若兵; 傅先明; 林彬; 季学兵; 牛朝诗; 汪业汉

    2012-01-01

    Objective To explore the possible brain mechanism of online game addiction(OGA)in terms of brain morphology through voxel-based morphometric(VBM)analysis.Methods Seventeen subjects with OGA and 17 age-and gender-matched healthy controls(HC group)were recruited from Department of Psychology at our hospital during February-December 2011.The internet addiction scale (IAS)was used to measure the degree of OGA tendency.Magnetic resonance imaging(MRI)scans were performed to acquire 3-demensional T1-weighted images.And FSL 4.1 software was employed to confirm regional gray matter volume changes.For the regions where OGA subjects showed significantly different gray matter volumes from the controls,the gray matter volumes of these areas were extracted,averaged and regressed against the scores of IAS.Results The OGA group had lower gray matter volume in left orbitofrontal cortex(OFC),left medial prefrontal cortex(mPFC),bilateral insula(INS),left posterior cingnlate cortex(PCC)and left supplementary motor area(SMA).Gray matter volumes of left OFC and bilateral INS showed a negative correlation with the scores of IAS(r =-0.65,r =-0.78,P <0.05).Conclusion Gray matter volume changes are present in online game addicts and they may be correlated with the occurrence and maintenance of OGA.%目的 采用基于体素脑形态学测量法探索网络游戏成瘾(OGA)患者脑灰质结构特点,从脑形态学角度解释网络游戏成瘾的可能神经机制.方法 选择安徽医科大学附属省立医院心理科2011年2至12月门诊就诊的网络游戏成瘾者(OGA组)和年龄性别相匹配的健康对照者(HC组)各17例,利用网络成瘾自评量表测评被试网络游戏成瘾程度;静息状态下采集被试磁共振数据,应用FSL软件进行基于体素脑形态学分析,确定OGA组灰质结构异常脑区的位置,并将异常脑区灰质容积率与网络成瘾自评量表得分进行相关性分析.结果 OGA组左侧眶额叶(OFC-L)、双侧岛叶(INS-L&R)

  3. Binding of fullerenes to amyloid beta fibrils: size matters.

    Science.gov (United States)

    Huy, Pham Dinh Quoc; Li, Mai Suan

    2014-10-01

    Binding affinity of fullerenes C20, C36, C60, C70 and C84 for amyloid beta fibrils is studied by docking and all-atom molecular dynamics simulations with the Amber force field and water model TIP3P. Using the molecular mechanic-Poisson Boltzmann surface area method one can demonstrate that the binding free energy linearly decreases with the number of carbon atoms of fullerene, i.e. the larger is the fullerene size, the higher is the binding affinity. Overall, fullerenes bind to Aβ9-40 fibrils stronger than to Aβ17-42. The number of water molecules trapped in the interior of 12Aβ9-40 fibrils was found to be lower than inside pentamer 5Aβ17-42. C60 destroys Aβ17-42 fibril structure to a greater extent compared to other fullerenes. Our study revealed that the van der Waals interaction dominates over the electrostatic interaction and non-polar residues of amyloid beta peptides play the significant role in interaction with fullerenes providing novel insight into the development of drug candidates against Alzheimer's disease.

  4. Oxidative DNA damage in mouse sperm chromosomes: Size matters.

    Science.gov (United States)

    Kocer, Ayhan; Henry-Berger, Joelle; Noblanc, Anais; Champroux, Alexandre; Pogorelcnik, Romain; Guiton, Rachel; Janny, Laurent; Pons-Rejraji, Hanae; Saez, Fabrice; Johnson, Graham D; Krawetz, Stephen A; Alvarez, Juan G; Aitken, R John; Drevet, Joël R

    2015-12-01

    Normal embryo and foetal development as well as the health of the progeny are mostly dependent on gamete nuclear integrity. In the present study, in order to characterize more precisely oxidative DNA damage in mouse sperm we used two mouse models that display high levels of sperm oxidative DNA damage, a common alteration encountered both in in vivo and in vitro reproduction. Immunoprecipitation of oxidized sperm DNA coupled to deep sequencing showed that mouse chromosomes may be largely affected by oxidative alterations. We show that the vulnerability of chromosomes to oxidative attack inversely correlated with their size and was not linked to their GC richness. It was neither correlated with the chromosome content in persisting nucleosomes nor associated with methylated sequences. A strong correlation was found between oxidized sequences and sequences rich in short interspersed repeat elements (SINEs). Chromosome position in the sperm nucleus as revealed by fluorescent in situ hybridization appears to be a confounder. These data map for the first time fragile mouse sperm chromosomal regions when facing oxidative damage that may challenge the repair mechanisms of the oocyte post-fertilization.

  5. Discrimination of dementia with Lewy bodies from Alzheimer's disease using voxel-based morphometry of white matter by statistical parametric mapping 8 plus diffeomorphic anatomic registration through exponentiated Lie algebra.

    Science.gov (United States)

    Nakatsuka, Tomoya; Imabayashi, Etsuko; Matsuda, Hiroshi; Sakakibara, Ryuji; Inaoka, Tsutomu; Terada, Hitoshi

    2013-05-01

    The purpose of this study was to identify brain atrophy specific for dementia with Lewy bodies (DLB) and to evaluate the discriminatory performance of this specific atrophy between DLB and Alzheimer's disease (AD). We retrospectively reviewed 60 DLB and 30 AD patients who had undergone 3D T1-weighted MRI. We randomly divided the DLB patients into two equal groups (A and B). First, we obtained a target volume of interest (VOI) for DLB-specific atrophy using correlation analysis of the percentage rate of significant whole white matter (WM) atrophy calculated using the Voxel-based Specific Regional Analysis System for Alzheimer's Disease (VSRAD) based on statistical parametric mapping 8 (SPM8) plus diffeomorphic anatomic registration through exponentiated Lie algebra, with segmented WM images in group A. We then evaluated the usefulness of this target VOI for discriminating the remaining 30 DLB patients in group B from the 30 AD patients. Z score values in this target VOI obtained from VSRAD were used as the determinant in receiver operating characteristic (ROC) analysis. Specific target VOIs for DLB were determined in the right-side dominant dorsal midbrain, right-side dominant dorsal pons, and bilateral cerebellum. ROC analysis revealed that the target VOI limited to the midbrain exhibited the highest area under the ROC curves of 0.75. DLB patients showed specific atrophy in the midbrain, pons, and cerebellum. Midbrain atrophy demonstrated the highest power for discriminating DLB and AD. This approach may be useful for determining the contributions of DLB and AD pathologies to the dementia syndrome.

  6. Global warming: it's not only size that matters

    Science.gov (United States)

    Hegerl, Gabriele C.

    2011-09-01

    impacts than temperatures that have occurred frequently due to internal climate variability. Determining when exactly temperatures enter unusual ranges may be done in many different ways (and the paper shows several, and more could be imagined), but the main result of first local emergence in low latitudes remains robust. A worrying factor is that the regions where the signal is expected to emerge first, or is already emerging are largely regions in Africa, parts of South and Central America, and the Maritime Continent; regions that are vulnerable to climate change for a variety of regions (see IPCC 2007), and regions which contribute generally little to global greenhouse gas emissions. In contrast, strong emissions of greenhouse gases occur in regions of low warming-to-variability ratio. To get even closer to the relevance of this finding for impacts, it would be interesting to place the emergence of highly unusual summer temperatures in the context not of internal variability, but in the context of variability experienced by the climate system prior to the 20th century, as, e.g. documented in palaeoclimatic reconstructions and simulated in simulations of the last millennium (see Jansen et al 2007). External forcing has moved the temperature range around more strongly for some regions and in some seasons than others. For example, while reconstructions of summer temperatures in Europe appear to show small long-term variations, winter shows deep drops in temperature in the little Ice Age and a long-term increase since then (Luterbacher et al 2004), which was at least partly caused by external forcing (Hegerl et al 2011a) and therefore 'natural variability' may be different from internal variability. A further interesting question in attempts to provide a climate-based proxy for impacts of climate change is: to what extent does the rapidity of change matter, and how does it compare to trends due to natural variability? It is reasonable to assume that fast changes impact

  7. Baryonic impact on the dark matter orbital properties of Milky Way-sized haloes

    Science.gov (United States)

    Zhu, Qirong; Hernquist, Lars; Marinacci, Federico; Springel, Volker; Li, Yuexing

    2017-04-01

    We study the orbital properties of dark matter haloes by combining a spectral method and cosmological simulations of Milky Way-sized Galaxies. We compare the dynamics and orbits of individual dark matter particles from both hydrodynamic and N-body simulations, and find that the fraction of box, tube and resonant orbits of the dark matter halo decreases significantly due to the effects of baryons. In particular, the central region of the dark matter halo in the hydrodynamic simulation is dominated by regular, short-axis tube orbits, in contrast to the chaotic, box and thin orbits dominant in the N-body run. This leads to a more spherical dark matter halo in the hydrodynamic run compared to a prolate one as commonly seen in the N-body simulations. Furthermore, by using a kernel-based density estimator, we compare the coarse-grained phase-space densities of dark matter haloes in both simulations and find that it is lower by ˜0.5 dex in the hydrodynamic run due to changes in the angular momentum distribution, which indicates that the baryonic process that affects the dark matter is irreversible. Our results imply that baryons play an important role in determining the shape, kinematics and phase-space density of dark matter haloes in galaxies.

  8. Size Matters: Penis Size and Sexual Position in Gay Porn Profiles.

    Science.gov (United States)

    Brennan, Joseph

    2017-08-18

    This article combines qualitative and quantitative textual approaches to the representation of penis size and sexual position of performers in 10 of the most visited gay pornography Web sites currently in operation. Specifically, in excess of 6,900 performer profiles sourced from 10 commercial Web sites are analyzed. Textual analysis of the profile descriptions is combined with a quantitative representation of disclosed penis size and sexual position, which is presented visually by two figures. The figures confirm that these sites generally market themselves as featuring penises that are extraordinarily large and find a sample-wide correlation between smaller penis sizes (5-6.5 inches) and receptive sexual acts (bottoming), and larger (8.5-13 inches) with penetrative acts (topping). These observations are supported through the qualitative textual readings of how the performers are described on these popular sites, revealing the narratives and marketing strategies that shape the construction of popular porn brands, performers, and profitable fantasies.

  9. Unraveling the size-dependent optical properties of dissolved organic matter

    DEFF Research Database (Denmark)

    Wünsch, Urban; Stedmon, Colin; Tranvik, Lars

    2017-01-01

    The size-dependent optical properties of dissolved organic matter (DOM) from four Swedish lakes were investigated using High Performance Size Exclusion Chromatography (HPSEC) in conjunction with online characterization of absorbance (240–600 nm) and fluorescence (excitation: 275 nm, emission: 300...... the characteristics of the low size range. Furthermore, the combination of HPSEC and parallel factor analysis (HPSEC-PARAFAC2) allowed the decomposition of DOM fluorescence chromatograms. Three humic-like components and one protein-like component with broadly overlapping molecular size distributions were identified...

  10. Size Matters: The Link between Staff Size and Perceived Organizational Support in Early Childhood Education

    Science.gov (United States)

    Ho, Dora; Lee, Moosung; Teng, Yue

    2016-01-01

    Purpose: The purpose of this paper is to examine the relationship between staff size and perceived organizational support (POS) in early childhood education (ECE) organizations. Design/methodology/approach: A territory-wide questionnaire survey was designed to investigate the perceptions of preschool teachers in Hong Kong on four dimensions of…

  11. How size matters: exploring the association between quality of mental health services and catchment area size.

    Science.gov (United States)

    Ala-Nikkola, Taina; Sadeniemi, Minna; Kaila, Minna; Saarni, Samuli; Kontio, Raija; Pirkola, Sami; Joffe, Grigori; Oranta, Olli; Wahlbeck, Kristian

    2016-08-12

    The diversity of mental health and substance abuse services (MHS) available to service users is seen as an indicator of the quality of the service system. In most countries MHS are provided by a mix of public, private and third sector providers. In Finland, officially, the municipalities are responsible for organizing the services needed, but the real extent and roles of private and third sector service providers are not known. Our previous study showed that the catchment area population size was strongly associated with diversity of mental health services. It is not known whether this was due to some types of services or some provider types being more sensitive to the size effect than others. The aim of this study was to investigate the association between area population size and diversity of mental health services, i.e. which types of services and which service providers' contributions are sensitive to population size. To map and classify services, we used the ESMS-R. The diversity of services was defined as the count of main types of care. Providers were classified as public, private or third sectors. The diversity of outpatient, residential and voluntary services correlated positively with catchment area population size. The strongest positive correlation between the size of population and services available was found in third sector activities followed by public providers, but no correlation was found for diversity of private services. The third sector and public corporations each provided 44 % of the service units. Third sector providers produced all self-help services and most of the day care services. Third sector and private companies provided a significant part (59 %) of the residential care service units. Significant positive correlations were found between size of catchment area population and diversity of residential, outpatient and voluntary services, indicating that these services concentrate on areas with larger population bases. The third sector

  12. Size Evolution of Early-Type Galaxies and Massive Compact Objects as the Dark Matter

    CERN Document Server

    Totani, Tomonori

    2009-01-01

    The dramatic size evolution of early-type galaxies from z ~ 2 to 0 poses a new challenge in the theory of galaxy formation, which may not be explained by the standard picture. It is shown here that the size evolution can be explained if the non-baryonic cold dark matter is composed of compact objects having a mass scale of ~10^5 M_sun. This form of dark matter is consistent with or only weakly constrained by the currently available observations. The kinetic energy of the dark compact objects is transferred to stars by dynamical friction, and stars around the effective radius are pushed out to larger radii, resulting in a pure size evolution. This scenario has several good properties to explain the observations, including the ubiquitous nature of size evolution and faster disappearance of higher density galaxies.

  13. Size matters!

    DEFF Research Database (Denmark)

    Pedersen, Jens Christian

    2010-01-01

    Når man taler om partikelforureningen fra den islandske vulkan er det afgørende at være opmærksom på at der er tale om en bred vifte af partikelstørrelser. De største partikler vil hurtigst falde ned til jordoverfladen, de mindste vil klumpe sammen, og tilbage er hovedsageligt partiklerne på 0,1-...

  14. Size matters

    DEFF Research Database (Denmark)

    Borgbo, T; Macek, M; Chrudimska, J;

    2016-01-01

    , intrafollicular levels of Anti-Müllerian Hormone (AMH), progesterone, oestradiol, testosterone and androstenedione, and GC gene expression levels of FSHR, LHR, AR, CYP19A1, and AMH. The long CAG repeat lengths were associated with significantly decreased testosterone levels, as compared to medium CAG repeats (P...... to evaluate the effects of the AR CAG repeat length on the intrafollicular hormone profiles, and the gene expression profiles of GC from human small antral follicles. In total, 190 small antral follicles (3-11 mm in diameter) were collected from 58 women undergoing ovarian cryopreservation for fertility...

  15. Sample size matters: Investigating the optimal sample size for a logistic regression debris flow susceptibility model

    Science.gov (United States)

    Heckmann, Tobias; Gegg, Katharina; Becht, Michael

    2013-04-01

    Statistical approaches to landslide susceptibility modelling on the catchment and regional scale are used very frequently compared to heuristic and physically based approaches. In the present study, we deal with the problem of the optimal sample size for a logistic regression model. More specifically, a stepwise approach has been chosen in order to select those independent variables (from a number of derivatives of a digital elevation model and landcover data) that explain best the spatial distribution of debris flow initiation zones in two neighbouring central alpine catchments in Austria (used mutually for model calculation and validation). In order to minimise problems arising from spatial autocorrelation, we sample a single raster cell from each debris flow initiation zone within an inventory. In addition, as suggested by previous work using the "rare events logistic regression" approach, we take a sample of the remaining "non-event" raster cells. The recommendations given in the literature on the size of this sample appear to be motivated by practical considerations, e.g. the time and cost of acquiring data for non-event cases, which do not apply to the case of spatial data. In our study, we aim at finding empirically an "optimal" sample size in order to avoid two problems: First, a sample too large will violate the independent sample assumption as the independent variables are spatially autocorrelated; hence, a variogram analysis leads to a sample size threshold above which the average distance between sampled cells falls below the autocorrelation range of the independent variables. Second, if the sample is too small, repeated sampling will lead to very different results, i.e. the independent variables and hence the result of a single model calculation will be extremely dependent on the choice of non-event cells. Using a Monte-Carlo analysis with stepwise logistic regression, 1000 models are calculated for a wide range of sample sizes. For each sample size

  16. Do Class and School Size Matter? A Crucial Issue to School Improvement

    Science.gov (United States)

    Cornelius, Elizabeth; Gaines, Raffaella; Gautney, Tara; Johnson, Gresha; Rainer, Robyn; Notar, Charles E.; Webb, Shelia A.

    2008-01-01

    Students in a first year Master's degree seminar were asked to find the answer to the question "Do Class and School Size Matter as A Crucial Issue to School Improvement?" The paper the students wrote is based on a review of the literature. The students determined that the question had several issues to be addressed before they could…

  17. Challenging "Size Matters" Messages: An Exploration of the Experiences of Critical Obesity Scholars in Higher Education

    Science.gov (United States)

    Cameron, Erin

    2016-01-01

    Given that postsecondary institutions are increasingly seen as sites to promote health, critical scholars are calling attention to how the contemporary Western weight-centred health paradigm reinforces a "size matters" message that is fueling harmful attitudes towards and judgments of bodies. As such, research that highlights strategies…

  18. Size Matters: FTIR Spectral Analysis of Apollo Regolith Samples Exhibits Grain Size Dependence.

    Science.gov (United States)

    Martin, Dayl; Joy, Katherine; Pernet-Fisher, John; Wogelius, Roy; Morlok, Andreas; Hiesinger, Harald

    2017-04-01

    The Mercury Thermal Infrared Spectrometer (MERTIS) on the upcoming BepiColombo mission is designed to analyse the surface of Mercury in thermal infrared wavelengths (7-14 μm) to investigate the physical properties of the surface materials [1]. Laboratory analyses of analogue materials are useful for investigating how various sample properties alter the resulting infrared spectrum. Laboratory FTIR analysis of Apollo fine (60%) causes a 'flattening' of the spectrum, with reduced reflectance in the Reststrahlen Band region (RB) as much as 30% in comparison to samples that are dominated by a high proportion of crystalline material. Apollo 15401,147 is an immature regolith with a high proportion of volcanic glass pyroclastic beads [2]. The high mafic mineral content results in a systematic shift in the Christiansen Feature (CF - the point of lowest reflectance) to longer wavelength: 8.6 μm. The glass beads dominate the spectrum, displaying a broad peak around the main Si-O stretch band (at 10.8 μm). As such, individual mineral components of this sample cannot be resolved from the average spectrum alone. Apollo 67481,96 is a sub-mature regolith composed dominantly of anorthite plagioclase [2]. The CF position of the average spectrum is shifted to shorter wavelengths (8.2 μm) due to the higher proportion of felsic minerals. Its average spectrum is dominated by anorthite reflectance bands at 8.7, 9.1, 9.8, and 10.8 μm. The average reflectance is greater than the other samples due to a lower proportion of glassy material. In each soil, the smallest fractions (0-25 and 25-63 μm) have CF positions 0.1-0.4 μm higher than the larger grain sizes. Also, the bulk-sample spectra mostly closely resemble the 0-25 μm sieved size fraction spectrum, indicating that this size fraction of each sample dominates the bulk spectrum regardless of other physical properties. This has implications for surface analyses of other Solar System bodies where some mineral phases or components

  19. From Source to City: Particulate Matter Concentration and Size Distribution Data from an Icelandic Dust Storm

    Science.gov (United States)

    Thorsteinsson, T.; Mockford, T.; Bullard, J. E.

    2015-12-01

    Dust storms are the source of particulate matter in 20%-25% of the cases in which the PM10health limit is exceeded in Reykjavik; which occurred approximately 20 times a year in 2005-2010. Some of the most active source areas for dust storms in Iceland, contributing to the particulate matter load in Reykjavik, are on the south coast of Iceland, with more than 20 dust storm days per year (in 2002-2011). Measurements of particle matter concentration and size distribution were recorded at Markarfljot in May and June 2015. Markarfljot is a glacial river that is fed by Eyjafjallajokull and Myrdalsjokull, and the downstream sandur areas have been shown to be significant dust sources. Particulate matter concentration during dust storms was recorded on the sandur area using a TSI DustTrak DRX Aerosol Monitor 8533 and particle size data was recorded using a TSI Optical Particle Sizer 3330 (OPS). Wind speed was measured using cup anemometers at five heights. Particle size measured at the source area shows an extremely fine dust creation, PM1 concentration reaching over 5000 μg/m3 and accounting for most of the mass. This is potentially due to sand particles chipping during saltation instead of breaking uniformly. Dust events occurring during easterly winds were captured by two permanent PM10 aerosol monitoring stations in Reykjavik (140 km west of Markarfljot) suggesting the regional nature of these events. OPS measurements from Reykjavik also provide an interesting comparison of particle size distribution from source to city. Dust storms contribute to the particular matter pollution in Reykjavik and their small particle size, at least from this source area, might be a serious health concern.

  20. Anodic aluminum oxide with fine pore size control for selective and effective particulate matter filtering

    Science.gov (United States)

    Zhang, Su; Wang, Yang; Tan, Yingling; Zhu, Jianfeng; Liu, Kai; Zhu, Jia

    2016-07-01

    Air pollution is widely considered as one of the most pressing environmental health issues. Particularly, atmospheric particulate matters (PM), a complex mixture of solid or liquid matter suspended in the atmosphere, are a harmful form of air pollution due to its ability to penetrate deep into the lungs and blood streams, causing permanent damages such as DNA mutations and premature death. Therefore, porous materials which can effectively filter out particulate matters are highly desirable. Here, for the first time, we demonstrate that anodic aluminum oxide with fine pore size control fabricated through a scalable process can serve as effective and selective filtering materials for different types of particulate matters (such as PM2.5, PM10). Combining selective and dramatic filtering effect, fine pore size control and a scalable process, this type of anodic aluminum oxide templates can potentially serve as a novel selective filter for different kinds of particulate matters, and a promising and complementary solution to tackle this serious environmental issue.

  1. Does screen size matter for smartphones? Utilitarian and hedonic effects of screen size on smartphone adoption.

    Science.gov (United States)

    Kim, Ki Joon; Sundar, S Shyam

    2014-07-01

    This study explores the psychological effects of screen size on smartphone adoption by proposing an extended Technology Acceptance Model (TAM) that integrates an empirical comparison between large and small screens with perceived control, affective quality, and the original TAM constructs. A structural equation modeling analysis was conducted on data collected from a between-subjects experiment (N=130) in which users performed a web-based task on a smartphone with either a large (5.3 inches) or a small (3.7 inches) screen. Results show that a large screen, compared to a small screen, is likely to lead to higher smartphone adoption by simultaneously promoting both the utilitarian and hedonic qualities of smartphones, which in turn positively influence perceived ease of use of-and attitude toward-the device respectively. Implications and directions for future research are discussed.

  2. Size matters: a single representation underlies our perceptions of heaviness in the size-weight illusion.

    Directory of Open Access Journals (Sweden)

    Gavin Buckingham

    Full Text Available In the size-weight illusion (SWI, a small object feels heavier than an equally-weighted larger object. It is thought that this illusion is a consequence of the way that we internally represent objects' properties--lifters expect one object to outweigh the other, and the subsequent illusion reflects a contrast with their expectations. Similar internal representations are also thought to guide the application of fingertip forces when we grip and lift objects. To determine the nature of the representations underpinning how we lift objects and perceive their weights, we examined weight judgments in addition to the dynamics and magnitudes of the fingertip forces when individuals lifted small and large exemplars of metal and polystyrene cubes, all of which had been adjusted to have exactly the same mass. Prior to starting the experiment, subjects expected the density of the metal cubes to be higher than that of the polystyrene cubes. Their illusions, however, did not reflect their conscious expectations of heaviness; instead subjects experienced a SWI of the same magnitude regardless of the cubes' material. Nevertheless, they did report that the polystyrene cubes felt heavier than the metal ones (i.e. they experienced a material-weight illusion. Subjects persisted in lifting the large metal cube with more force than the small metal cube, but lifted the large polystyrene cube with roughly the same amount of force that they used to lift the small polystyrene cube. These findings suggest that our perceptual and sensorimotor representations are not only functionally independent from one another, but that the perceptual system represents a more single, simple size-weight relationship which appears to drive the SWI itself.

  3. Does Size Matter? The Implications of Firm Size on Enterprise Systems Success

    Directory of Open Access Journals (Sweden)

    Darshana Sedera

    2016-04-01

    Full Text Available With the increasing emphasis on globalization and consumer demands in highly competitive markets, organizations have attempted to integrate and standardize across their corporate subsidiaries by implementing Enterprise Systems (ES. In such corporate-wide ES implementations, system requirements are dictated by headquarters, favouring large subsidiaries, and thus potentially compromising the unique business requirements of smaller units. This research reports findings from an ES initiative within a group of large, medium, and small organizations, where the impact of organization size is assessed in relation to the level of system success and knowledge-management competence. The results of this analysis suggest that (i large organizations, in contrast to their smaller counterparts, receive greater benefits in terms of both Individual and Organizational Impacts, (ii while no such differences were observed in relation to System and Information Quality. Similarly, (iii no differences were observed in relation to knowledge-creation competencies amongst large, medium, and small organizations. However, (iv differences were observed between the large and smaller firms on their Knowledge-Retention and Knowledge-Transfer competencies. 

  4. White matter microstructure asymmetry: effects of volume asymmetry on fractional anisotropy asymmetry.

    Science.gov (United States)

    Takao, H; Hayashi, N; Ohtomo, K

    2013-02-12

    Diffusion tensor imaging (DTI) provides information regarding white matter microstructure; however, macroscopic fiber architectures can affect DTI measures. A larger brain (fiber tract) has a 'relatively' smaller voxel size, and the voxels are less likely to contain more than one fiber orientation and more likely to have higher fractional anisotropy (FA). Previous DTI studies report left-to-right differences in the white matter; however, these may reflect true microscopic differences or be caused purely by volume differences. Using tract-based spatial statistics, we investigated left-to-right differences in white matter microstructure across the whole brain. Voxel-wise analysis revealed a large number of white matter volume asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. In many white matter regions, FA asymmetry was positively correlated with volume asymmetry. Voxel-wise analysis with adjustment for volume asymmetry revealed many white matter FA asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. The voxel-wise analysis showed a reduced number of regions with significant FA asymmetry compared with analysis performed without adjustment for volume asymmetry; however, the overall trend of the results was unchanged. The results of the present study suggest that these FA asymmetries are not caused by volume differences and reflect microscopic differences in the white matter.

  5. Size Matters!. Birth Size and a Size-Independent Stochastic Term Determine Asexual Reproduction Dynamics in Freshwater Planarians

    Science.gov (United States)

    Thomas, Michael A.; Quinodoz, Sofia; Schötz, Eva-Maria

    2012-09-01

    Asexual reproduction by division in higher organisms is rare, because a prerequisite is the ability to regenerate an entire organism from a piece of the original body. Freshwater planarians are one of the few animals that can reproduce this way, but little is known about the regulation of their reproduction cycles or strategies. We have previously shown that a planarian's reproduction strategy is randomized to include fragmentations, producing multiple offspring, as well as binary fissions, and can be partially explained by a maximum relative entropy principle. In this study we attempt to decompose the factors controlling their reproduction cycle. Based on recent studies on the cell cycle of budding yeast, which suggest that molecular noise in gene expression and cell size at birth together control cell cycle variability, we investigated whether the variability in planarian reproduction waiting times could be similarly regulated. We find that such a model can indeed explain the observed distribution of waiting times between birth and next reproductive event, suggesting that birth size and a stochastic noise term govern the reproduction dynamics of asexual planarians.

  6. Voxel-based morphometry on grey matter concentration of the brain in patients with post stroke depression%脑卒中后抑郁患者大脑灰质密度基于体素的形态测量学研究

    Institute of Scientific and Technical Information of China (English)

    吴磊; 吴文; 郭荣; 曹安; 杨建明

    2013-01-01

    目的 运用基于体素的形态测量学分析(VBM)方法,探讨脑卒中后抑郁(PSD)患者双侧前额叶、海马及前扣带回灰质密度特征. 方法 选择自2012年6月至2013年3月南方医科大学珠江医院康复科收住院的10例PSD患者(PSD组)和13例脑卒中后无抑郁患者(non-PSD组)接受3D高分辨率TlWI序列磁共振扫描,利用基于SPM8的DARTEL工具箱对扫描获得的结构图像进行预处理,并将双侧前额叶、海马及前扣带回作为感兴趣区,最后用双样本t检验比较PSD组与non-PSD组患者双侧前额叶、海马及前扣带回灰质密度差异,以P<0.001(未校正)、相连体素大于200以上的组块视为有差异的脑区,同时采用双变量相关分析方法分析汉密尔顿抑郁量表(HAMD)评分与PSD组中组间差异有统计学意义的组块的灰质密度值的相关性. 结果 (1)与non-PSD组相比,PSD组患者右侧前额叶(额中回)灰质密度明显下降(BA10;MNI坐标:x=25.5,y=46.5,z=-l.5;相连体素260 voxels;t=30.28,P<0.001未校正),双侧前扣带回灰质密度明显增高(BA32;MNI坐标:x=1.5,y=45,z=6;相连体素495 voxels; t=-13.29,P<0.001未校正),而双侧海马灰质密度未发现差异有统计学意义(BA30; MNI坐标:x=18,y=-34.5,z=3;相连体素164 voxels;t=5.15,P<0.001未校正).(2)在PSD组中,HAMD评分与右侧额中回灰质密度值呈显著正相关性(r=0.687,P=-0.000),与双侧前扣带回灰质密度值无显著相关性(r=0.321,P>0.0S). 结论 PSD患者同样存在边缘-皮质环路多个脑区灰质结构的异常,右侧额中回灰质密度值对PSD患者抑郁严重程度的判断有一定的临床价值.%Objective To study the differences of gray matter density in the prefrontal cortex,anterior cingulate cortex and hippocampus of patients with post stroke depression (PSD) by using voxel-based morphometry (VBM).Methods Ten patients with PSD and 13 patients without PSD underwent examination of three-dimensional high-resolution T1

  7. Characteristic size and mass of galaxies in the Bose–Einstein condensate dark matter model

    Directory of Open Access Journals (Sweden)

    Jae-Weon Lee

    2016-05-01

    Full Text Available We study the characteristic length scale of galactic halos in the Bose–Einstein condensate (or scalar field dark matter model. Considering the evolution of the density perturbation we show that the average background matter density determines the quantum Jeans mass and hence the spatial size of galaxies at a given epoch. In this model the minimum size of galaxies increases while the minimum mass of the galaxies decreases as the universe expands. The observed values of the mass and the size of the dwarf galaxies are successfully reproduced with the dark matter particle mass m≃5×10−22 eV. The minimum size is about 6×10−3m/Hλc and the typical rotation velocity of the dwarf galaxies is O(H/m c, where H is the Hubble parameter and λc is the Compton wave length of the particle. We also suggest that ultra compact dwarf galaxies are the remnants of the dwarf galaxies formed in the early universe.

  8. A voxel-based morphometric study on change of gray matter structures in cerebral palsy%基于体素形态测量学检测脑性瘫痪患儿脑灰质结构改变

    Institute of Scientific and Technical Information of China (English)

    王莹; 王海宝; 余永强; 徐丽艳; 陈玉萍; 吴德

    2015-01-01

    Objective To measure gray matter volume of whole brain with voxel-based morphometry (VBM) method and to study brain structures associated with gross motor function.Method Forty children with cerebral palsy were recruited in the authors' hospital from Oct.2012 to Dec.2013 (26 male,14 female cases,average age (3.6 ± 2.0) years).Gross motor function classification system (GMFCS) for children was used to obtain their motor function.The whole-brain three dimensional magnetic resonance imaging (MRI) was performed on a 3.0 T MRI scanner.The data were segmented by VBM 5,and the whole brain volumes of gray matter,white matter and cerebospinal fluid were produced.Correlation analysis was used to analyze the correlation of GMFCS with whole brain volumes using SPM 5 in Matalab 7.1.Result The volume in left meditemporal gyrus (Z =3.57) and inferior temporal gyrus (Z =3.40),right thalamus and pallidum (Z =3.36),left thalamus and pallidum (Z =2.76),left supramarginal gyrus (Z =3.14),left precuneus gyrus (Z =3.00),right dorsolateral superior frontal gyrus (Z =3.08),right superior and medial occipital gyrus (Z =2.84) significantly increased as aggravation of gross motor dysfunction.The volume of the left medial orbitofrontal lobe and anterior cingulate (Z =3.28,3.02),left medial superior frontal gyrus (Z =3.19),left caudate (Z =3.04,2.94,2.92),left cerebellum (Z =2.94),right cerebellum (Z =2.97),left parahippocampal (Z =3.94),right parahippocampal (Z =3.43,3.00),left insula (Z =3.50),right insula (Z =3.41,3.80),left lingual (Z =3.37),right lingual (Z =3.30),left post cingulum (Z =2.73),left midioccipital gyrus (Z =2.92) and right miditemporal gyrus (Z =3.05) significantly reduced as the aggravation of gross motor dysfunction (P all < 0.005).Conclusion GMFCS in children with cerebral palsy is related to abnormalities of brain gray matter structure for motor,emotion,memory and default model network when examined with VBM method.%目的 应用基于体素形态测量学(VBM)技术

  9. Academic literacy of South African higher education level students: Does vocabulary size matter?

    Directory of Open Access Journals (Sweden)

    Déogratias Nizonkiza

    2015-12-01

    Full Text Available This study explores the extent to which vocabulary size matters in academic literacy. Participants (first-year students at North-West University were administered the Vocabulary Levels Test (Schmitt, Schmitt and Clapham 2001. Scores from the test were used to estimate students’ vocabulary size and were subsequently mapped onto the levels distinguished by the Test of Academic Literacy Levels (TALL. Estimates show that, on average, the vocabulary size of first-year students at North-West University is approximately 4,500 word families, a size large enough to allow them to follow lectures in English. Furthermore, students with large vocabularies were found to have higher academic literacy proficiency, which establishes a strong relationship between vocabulary size and academic literacy. This relationship was also observed at the different word frequency bands the Vocabulary Levels Test consists of. These results support previous findings which established a relationship between vocabulary size and reading (cf. Nation 2006, and between vocabulary size and overall language proficiency (cf. Beglar 2010, Meara and Buxton 1987, Meara and Jones 1988, Nation and Beglar 2007, which could be extended to academic literacy. Furthermore, a stronger relationship between vocabulary size and academic literacy was found towards more infrequent word bands, indicating that infrequent word bands may best predict academic literacy. On the basis of these findings, we discuss possible strategies to adopt in order to assist some first-years with expanding their vocabularies. 

  10. Copper and Zinc Enrichment in Different Size Fractions of Organic Matter from Polluted Soils

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming-Kui; KE Zi-Xia

    2004-01-01

    Bioavailability of heavy metals in soil organic matter depends on its components. Characterization of heavy metal distributions in different fractions of soil organic matter is needed for better understanding of the fate of heavy metals. This study investigated the accumulation and partitioning of copper and zinc among different size particulate organic matter (POM) fractions in polluted soils from a former iron ore processing site in western Shaoxing County, Zhejiang Province. Physical fractionations were carried out to separate soil primary particles according to their size and density. Copper and Zn had a heterogeneous distribution among soil particle fractions. Copper and Zn were significantly (p < 0.05) enriched in the POM fractions. > 0.05 mm POM and < 0.05 mm fine soil fractions were mainly responsible for Cu and Zn retention in soils. The POM fraction contained up to 1 322 mg Cu kg-1 and 1 115 mg Zn kg-1 and the fine soil fraction contained up to 422 mg Cu kg-1 and 537 mg Zn kg-1. The total POM fraction was responsible for 15.8%-41.2% and 12.2%-31.7% of the total amount of Cu and Zn, respectively, in the polluted soils. The percentages of Cu and Zn associated with organic matter in < 0.05 mm fine soil fractions for the polluted soils ranged from 14.1% to 24.5%, and 5.4% to 15.8%, respectively. Accumulation of soil organic matter could increase enrichment of Gu (or Zn) in the POM fractions. Also, Cu provided a greater enrichment in the POM fractions than Zn.

  11. Laser-induced forward transfer (LIFT) of congruent voxels

    Energy Technology Data Exchange (ETDEWEB)

    Piqué, Alberto, E-mail: pique@nrl.navy.mil [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Kim, Heungsoo; Auyeung, Raymond C.Y.; Beniam, Iyoel [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Breckenfeld, Eric [National Research Council Fellow at the Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-06-30

    Highlights: • Laser-induced forward transfer (LIFT) is demonstrated with high viscosity Ag nanopaste. • Under the right conditions (viscosity and fluence) the transfer of congruent voxels was achieved. • For viscosities under 100 Pa s, congruent voxel transfer of silver nano-suspensions is only possible under a very narrow range of conditions. • For viscosities over 100 Pa s, congruent voxel transfer of silver nano-pastes works over a wider range of fluences, donor substrate thickness, gap distances and voxel areas. • The laser transfer of congruent voxels can be used for printing electronic patterns in particular interconnects. - Abstract: Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D

  12. 基于体素的形态测量学观察两种亚型血管性认知障碍患者脑灰质萎缩的差异%Volume differences in regional gray matter between patients with two subtypes of vascular cognitive impairment:A voxel-based morphometric observation

    Institute of Scientific and Technical Information of China (English)

    李秋雨; 沈智威; 杨忠现; 肖叶玉; 吴仁华

    2013-01-01

    Objective To investigate volume differences in regional gray matter between patients suffered from mild cognitive impairment associated with periventricular white matter hyperintensities (PWMH) and strategic single-infarct (SSI)by using voxel-based morphometry (VBM) method.Methods Participants were neuropsychologically tested to characterize cognitive function,and then 24 cases of cerebral infarction in patients with mild cognitive impairment were collected and underwent MR scan.According to the results,the patients were divided into PWMH group (n=14) and SSI group (n=10).Meanwhile,16 healthy controls (control group) in the same period were included,whose neuropsychological testing were normal and no obvious infarct was found on MRI.Whole brain regional differences in gray matter volume among 3 groups were examined with VBM.Results Compared with SSI group,the volume of bilateral temporal lobe and bilateral frontal gray matter obviously reduced in PWMH group,especially in bilateral temporal lobes.The lobe atrophy volume difference of left temporal was 4086 voxels,of the right temporal lobe was 4154 voxels,of the left and right frontal lobe was 1718 voxels and 1141 voxels,respectively.Conclusion The volume of regional gray matter between patients with SSI and PWMH shows significant difference.The characteristics of gray matter atrophy in PWMH are similar to degenerative disease,prompting that merger or secondary neurodegenerative changes in this vascular cognitive impairment subtypes can not be ruled out.%目的 利用基于体素的形态测量学(VBM)方法观察由皮质下微血管病变导致的脑室周围白质脱髓鞘(PWMH)后轻度认知障碍的患者与关键部位单发梗死(SSI)后轻度认知障碍的患者灰质萎缩的差异.方法 根据神经心理学测试结果收集24例具有轻度认知障碍的脑梗死患者,根据MRI结果将其分为PWMH组(n=14)和SSI组(n=10);另选同期16名神经心理学测试结果正常、脑实质内未见明

  13. Baryonic impact on the dark matter distribution in Milky Way-size galaxies and their satellites

    CERN Document Server

    Zhu, Qirong; Maji, Moupiya; Li, Yuexing; Springel, Volker; Hernquist, Lars

    2015-01-01

    We study the impact of baryons on the distribution of dark matter in a Milky Way-size halo by comparing a high-resolution, moving-mesh cosmological simulation with its dark matter-only counterpart. We identify three main processes related to baryons -- adiabatic contraction, tidal disruption and reionization -- which jointly shape the dark matter distribution in both the main halo and its subhalos. The relative effect of each baryonic process depends strongly on the subhalo mass. For massive subhalos with maximum circular velocity $v_{\\rm max} > 35 km/s$, adiabatic contraction increases the dark matter concentration, making these halos less susceptible to tidal disruption. For low-mass subhalos with $v_{\\rm max} < 20 km/s$, reionization effectively reduces their mass on average by $\\approx$ 30% and $v_{\\rm max}$ by $\\approx$ 20%. For intermediate subhalos with $20 km/s < v_{\\rm max} < 35 km/s$, which share a similar mass range as the classical dwarf spheroidals, strong tidal truncation induced by the...

  14. Laser-induced forward transfer (LIFT) of congruent voxels

    Science.gov (United States)

    Piqué, Alberto; Kim, Heungsoo; Auyeung, Raymond C. Y.; Beniam, Iyoel; Breckenfeld, Eric

    2016-06-01

    Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D and 3D microstructures by adjusting the viscosity of the nano-suspension and laser transfer parameters.

  15. The stability of stellar disks in Milky-Way sized dark matter halos

    CERN Document Server

    Yurin, Denis

    2014-01-01

    We employ an improved methodology to insert live stellar disks into high-resolution dark matter simulations of Milky Way sized halos, allowing us to investigate the fate of thin stellar disks in the tumultuous environment of cold dark matter structures. We study a set of eight different halos, drawn from the Aquarius simulation project, in which stellar disks are adiabatically grown with a prescribed structure, and then allowed to self-consistently evolve. The initial velocity distribution is set-up in very good equilibrium with the help of the GALIC code. We find that the residual triaxiality of the halos leads to significant disk tumbling, qualitatively confirming earlier work. We show that the disk turning motion is unaffected by structural properties of the galaxies such as the presence or absence of a bulge or bar. In typical Milky Way sized dark matter halos, we expect an average turning of the disks by about 40 degrees between z=1 and z=0, over the coarse of 6 Gyr. We also investigate the impact of the...

  16. THE DIFFERENCES OF GRAY MATTER BETWEEN CHRONIC CIGARETTE SMOKERS AND NONSMOKERS:A VOXEL BASED MORPHOMETRY(VBM)STUDY%吸烟者与不吸烟者灰质体积的差异-基于体素的形态学研究(VBM)

    Institute of Scientific and Technical Information of China (English)

    廖艳辉; 唐劲松; 刘铁桥; 陈晓岗; 郝伟

    2011-01-01

    Objective: Assessing volumetric abnormalities of grey matter in chronic cigarette smokers. Methods:We used three -dimensional structural magnetic resonance images and voxel -based morphometry method in 44 smokers and 44 non - smoking control individuals to assess gray matter volume differences between the two groups. Results: We found a decrease in gray matter volume in left thalamus,medial frontal cortex and anterior eingulate of smokers in comparison to controls (P <0.001 uncorrected for multiple comparisons at voxel- level). Conclusion:This study showed the reduction of regional (left thalamus, medial frontal cortex and anterior cingulated) gray matter volume in smokers. Those results might better guide future research into the pathogenesis of chronic smoking.%目的:了解慢性吸烟者是否存在脑灰质改变.方法:采用磁共振三维成像技术对44名吸烟者和44名相匹配的不吸烟者脑结构扫描,利用基于体素的形态学分析方法进行吸烟与非吸烟者两组之间的脑灰质体积比较.结果:与不吸烟者组相比,吸烟者组的左侧丘脑、额中回区和扣带回灰质体积下降(P<0.001,未纠正).结论:本研究发现了慢性吸烟者的脑灰质改变(丘脑、额中回区和扣带回灰质体积下降),此结果将有助于进一步研究慢性吸烟的大脑作用机制.

  17. Gender versus brain size effects on subcortical gray matter volumes in the human brain.

    Science.gov (United States)

    Tang, Tianyu; Jiao, Yun; Wang, Xunheng; Lu, Zuhong

    2013-11-27

    Previous studies had reported that volume differences of gray matter (GM) in subcortical regions of the human brain were mainly caused by gender. Meanwhile, other studies had found that the distribution of GM in the human brain varied based on individual brain sizes. Main effects of volume differences of GM in subcortical regions remain unclear. Therefore, the goals of this study are twofold, namely, to determine the main effects of volume differences of GM in subcortical regions of the human brain and to investigate the independent or joint contribution of gender and brain size to subcortical volume differences. In this study, 40 male and 40 female subjects with comparable brain sizes were selected from a population of 198 individuals. The sample was divided into the following four groups: male and female groups with comparably large brain sizes and male and female groups with comparably small brain sizes. The main effects of gender and of brain size and interactions between both factors in subcortical GM volumes were examined by analyses of covariance (ANCOVAs) using a 2×2 design matrix. Volumes of GM in subcortical regions were extracted and measured by an automatic segmentation method. Furthermore, we used two datasets to test the reliability of our methods. In both datasets, we found significant brain size effects in the right amygdala and the bilateral caudate nucleus and significant gender effects in the bilateral putamen. No interactions between brain size and gender were found. In conclusion, both gender and brain size independently contributed to volume distribution in different subcortical areas of the human brain.

  18. Particle size distributions and organic-inorganic compositions of suspended particulate matters around the Bohai Strait

    Science.gov (United States)

    Wang, Xiao; Bian, Changwei; Bi, Rong; Jiang, Wensheng; Zhang, Hua; Zhang, Xueqing

    2017-02-01

    Laser in situ scattering and transmissometry (LISST) significantly improves our ability to assess particle size distribution (PSD) in seawater, while wide-ranging measurements of the organic-inorganic compositions of suspended particulate matters (SPM) are still difficult by using traditional methods such as microscopy. In this study, PSD properties and SPM compositions around the Bohai Strait (China) were investigated based on the measurements by LISST in combination with hydro-biological parameters collected from a field survey in summer 2014. Four typical PSD shapes were found in the region, namely right-peak, left-peak, double-peak and negative-skew shapes. The double-peak and negative-skew shapes may interconvert into each other along with strong hydrodynamic variation. In the upper layer of the Bohai Sea, organic particles were in the majority, with inorganic particles rarely observed. In the bottom layer, SPM were the mixture of organic and inorganic matters. LISST provided valuable baseline information on size-resolved organic-inorganic compositions of SPM: the size of organic particles mainly ranged from 4 to 20 μm and 40 to 100 μm, while most SPM ranging from 20 to 40 μm were composed of inorganic sediment.

  19. Measuring Sub-micron Size Fractionated Particulate Matter on Aluminum Impactor Disks

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, B A; Zermeno, P; Hwang, H; Young, T M

    2009-07-28

    Sub-micron sized airborne particulate matter is not collected well on regular quartz or glass fiber filter papers. We used a micro-orifice uniform deposit impactor (MOUDI) to size fractionate particulate matter (PM) into six size fractions and deposit it on specially designed high purity thin aluminum disks. The MOUDI separated PM into fractions 56-100 nm, 100-180 nm, 180-320 nm, 320-560 nm, 560-1000 nm, and 1000-1800 nm. Since MOUDI have low flow rates, it takes several days to collect sufficient carbon on 47 mm foil disks. The small carbon mass (20-200 microgram C) and large aluminum substrate ({approx}25 mg Al) presents several challenges to production of graphite targets for accelerator mass spectrometry (AMS) analysis. The Al foil consumes large amounts of oxygen as it is heated and tends to melt into quartz combustion tubes, causing gas leaks. We describe sample processing techniques to reliably produce graphitic targets for {sup 14}C-AMS analysis of PM deposited on Al impact foils.

  20. Study on the consistency of the voxel of two photon polymerization with inclined beam

    Science.gov (United States)

    Cheng, Kai; Zhou, Xiaoqin; Zheng, Xu; Lin, Jieqiong

    2016-12-01

    In the process of two photon polymerization, the focused beam should be perpendicular to the materials to be processed. But actually it is hard to control, because of the errors of the optical system and the three-dimensional motion platform. So, the inconsistencies of voxels in size and angle due to the errors mentioned above will seriously impact the surface quality of the products. In this paper, the size, angle and location of the titled voxels formed by inclined beam are simulated according to matrix optics and polymerization theory. According to the simulation results, a method for angle errors compensation with the aid of scanning galvanometer is proposed. Although the angle of the voxels can be controlled by scanning galvanometer, but the deflection angles of the scanning galvanometer have a certain range, it should be lower than 3°, or the deformation of the voxels will be serious. Therefore the consistency of the voxel in both size and angle will be ensured.

  1. SIZE DISTRIBUTION AND RATE OF PRODUCTION OF AIRBORNE PARTICULATE MATTER GENERATED DURING METAL CUTTING

    Energy Technology Data Exchange (ETDEWEB)

    M.A. Ebadian, Ph.D.; S.K. Dua, Ph.D., C.H.P.; Hillol Guha, Ph.D.

    2001-01-01

    During deactivation and decommissioning activities, thermal cutting tools, such as plasma torch, laser, and gasoline torch, are used to cut metals. These activities generate fumes, smoke and particulates. These airborne species of matter, called aerosols, may be inhaled if suitable respiratory protection is not used. Inhalation of the airborne metallic aerosols has been reported to cause ill health effects, such as acute respiratory syndrome and chromosome damage in lymphocytes. In the nuclear industry, metals may be contaminated with radioactive materials. Cutting these metals, as in size reduction of gloveboxes and tanks, produces high concentrations of airborne transuranic particles. Particles of the respirable size range (size < 10 {micro}m) deposit in various compartments of the respiratory tract, the fraction and the site in the respiratory tract depending on the size of the particles. The dose delivered to the respiratory tract depends on the size distribution of the airborne particulates (aerosols) and their concentration and radioactivity/toxicity. The concentration of airborne particulate matter in an environment is dependent upon the rate of their production and the ventilation rate. Thus, measuring aerosol size distribution and generation rate is important for (1) the assessment of inhalation exposures of workers, (2) the selection of respiratory protection equipment, and (3) the design of appropriate filtration systems. Size distribution of the aerosols generated during cutting of different metals by plasma torch was measured. Cutting rates of different metals, rate of generation of respirable mass, as well as the fraction of the released kerf that become respirable were determined. This report presents results of these studies. Measurements of the particles generated during cutting of metal plates with a plasma arc torch revealed the presence of particles with mass median aerodynamic diameters of particles close to 0.2 {micro}m, arising from

  2. Input related microbial carbon dynamic of soil organic matter in particle size fractions

    Science.gov (United States)

    Gude, A.; Kandeler, E.; Gleixner, G.

    2012-04-01

    This paper investigated the flow of carbon into different groups of soil microorganisms isolated from different particle size fractions. Two agricultural sites of contrasting organic matter input were compared. Both soils had been submitted to vegetation change from C3 (Rye/Wheat) to C4 (Maize) plants, 25 and 45 years ago. Soil carbon was separated into one fast-degrading particulate organic matter fraction (POM) and one slow-degrading organo-mineral fraction (OMF). The structure of the soil microbial community were investigated using phospholipid fatty acids (PLFA), and turnover of single PLFAs was calculated from the changes in their 13C content. Soil enzyme activities involved in the degradation of carbohydrates was determined using fluorogenic MUF (methyl-umbelliferryl phosphate) substrates. We found that fresh organic matter input drives soil organic matter dynamic. Higher annual input of fresh organic matter resulted in a higher amount of fungal biomass in the POM-fraction and shorter mean residence times. Fungal activity therefore seems essential for the decomposition and incorporation of organic matter input into the soil. As a consequence, limited litter input changed especially the fungal community favouring arbuscular mycorrhizal fungi. Altogether, supply and availability of fresh plant carbon changed the distribution of microbial biomass, the microbial community structure and enzyme activities and resulted in different priming of soil organic matter. Most interestingly we found that only at low input the OMF fraction had significantly higher calculated MRT for Gram-positive and Gram-negative bacteria suggesting high recycling of soil carbon or the use of other carbon sources. But on average all microbial groups had nearly similar carbon uptake rates in all fractions and both soils, which contrasted the turnover times of bulk carbon. Hereby the microbial carbon turnover was always faster than the soil organic carbon turnover and higher carbon input

  3. Stroke Damage Is Exacerbated by Nano-Size Particulate Matter in a Mouse Model.

    Science.gov (United States)

    Liu, Qinghai; Babadjouni, Robin; Radwanski, Ryan; Cheng, Hank; Patel, Arati; Hodis, Drew M; He, Shuhan; Baumbacher, Peter; Russin, Jonathan J; Morgan, Todd E; Sioutas, Constantinos; Finch, Caleb E; Mack, William J

    2016-01-01

    This study examines the effects of nano-size particulate matter (nPM) exposure in the setting of murine reperfused stroke. Particulate matter is a potent source of inflammation and oxidative stress. These processes are known to influence stroke progression through recruitment of marginally viable penumbral tissue into the ischemic core. nPM was collected in an urban area in central Los Angeles, impacted primarily by traffic emissions. Re-aerosolized nPM or filtered air was then administered to mice through whole body exposure chambers for forty-five cumulative hours. Exposed mice then underwent middle cerebral artery occlusion/ reperfusion. Following cerebral ischemia/ reperfusion, mice exposed to nPM exhibited significantly larger infarct volumes and less favorable neurological deficit scores when compared to mice exposed to filtered air. Mice exposed to nPM also demonstrated increases in markers of inflammation and oxidative stress in the region of the ischemic core. The findings suggest a detrimental effect of urban airborne particulate matter exposure in the setting of acute ischemic stroke.

  4. Impact of breast milk on intelligence quotient, brain size, and white matter development.

    Science.gov (United States)

    Isaacs, Elizabeth B; Fischl, Bruce R; Quinn, Brian T; Chong, Wui K; Gadian, David G; Lucas, Alan

    2010-04-01

    Although observational findings linking breast milk to higher scores on cognitive tests may be confounded by factors associated with mothers' choice to breastfeed, it has been suggested that one or more constituents of breast milk facilitate cognitive development, particularly in preterms. Because cognitive scores are related to head size, we hypothesized that breast milk mediates cognitive effects by affecting brain growth. We used detailed data from a randomized feeding trial to calculate percentage of expressed maternal breast milk (%EBM) in the infant diet of 50 adolescents. MRI scans were obtained (mean age=15 y 9 mo), allowing volumes of total brain (TBV) and white and gray matter (WMV, GMV) to be calculated. In the total group, %EBM correlated significantly with verbal intelligence quotient (VIQ); in boys, with all IQ scores, TBV and WMV. VIQ was, in turn, correlated with WMV and, in boys only, additionally with TBV. No significant relationships were seen in girls or with gray matter. These data support the hypothesis that breast milk promotes brain development, particularly white matter growth. The selective effect in males accords with animal and human evidence regarding gender effects of early diet. Our data have important neurobiological and public health implications and identify areas for future mechanistic study.

  5. 氯胺酮依赖者的额叶灰质体积研究——基于体素的形态学研究( VBM)%Volumetric abnormalities of gray matter in ketamine dependent patients: a voxel based morphometry study

    Institute of Scientific and Technical Information of China (English)

    廖艳辉; 詹劲松; 王绪轶; 谌红献; 向小军; 刘铁桥; 陈晓岗; 郝伟

    2012-01-01

    Objective Using three - dimensional magnetic resonance imaging to assess volumetric abnormalities of grey matter in chronic ketamine dependent subjects. Methods We used voxel based morphometry in conjunction with statistical parametric mapping on the structural magnetic resonance images of ketamine - dependent (n =41) and drug -naive control individuals (n = 44) to assess differences between the two groups in gray matter volume. Results We found a decrease in gray matter volume in bilateral frontal (left superior frontal and right middle frontal) cortex of ketamine patients in comparison to controls ( P < 0. 05 corrected for multiple comparisons at cluster - level) . Also, we found that the duration (months) of ketamine use was negatively correlated with gray matter volume in bilateral frontal cortex while the estimated total lifetime ketamine consumption was only negatively correlated with gray matter volume in left superior frontal cortex. Conclusions This is the first voxel - based morphometry study showing reduction of frontal gray matter volume in patients with ketamine dependence and showing the correlation of duration of ketamine use and cumulative doses of ketamine with decrease of frontal gray matter volume. Brain structural study of the affected areas in patients with ketamine dependence might better guide future research into the poorly understood condition of ketamine addiction and its correlates of schizophrenia.%目的 研究慢性氯胺酮依赖者脑灰质改变情况.方法 采用基本体素的形态学分析方法 对41名氯胺酮依赖者和44名未使用任何成瘾物质的健康志愿者进行两组之间的脑灰质体积比较.结果 与对照组相比,氯胺酮依赖组的双侧额叶区(左额上回和右额中回)灰质体积下降(P <0.05,纠正后,cluster水平);氯胺酮使用的时间(月)与双侧额叶灰质体积呈负相关,而估计的氯胺酮使用总量只和左额上回的灰质体积呈负相关.结论 本研究首次

  6. Accumulation of three different sizes of particulate matter on plant leaf surfaces: Effect on leaf traits

    Directory of Open Access Journals (Sweden)

    Chen Xiaoping

    2015-01-01

    Full Text Available Plants not only improve air quality by adsorbing particulate matter (PM on leaf surfaces but can also be affected by their accumulation. In this study, a field investigation was performed in Wuhan, China, into the relationship between seven leaf traits and the accumulation of three different sizes of PM (PM11, PM2.5 and PM0.2 on leaves. The retention abilities of plant leaves with respect to the three sizes of PM differed significantly at different sites and species. The average PM retention capabilities of plant leaves and specific leaf area (SLA were significantly greater in a seriously polluted area, whereas the average values of chlorophyll a (Chl a, chlorophyll b (Chl b, total chlorophyll, carotenoid, pH and relative water content (RWC were greater at the control site. SLA significantly positively correlated with the size of PM, but Chl a, Chl b, total chlorophyll, RWC significantly negatively correlated with the size of PM, whereas the pH did not correlate significantly with the the PM fractions. Additionally, SLA was found to be affected by large particles (PM11, p<0.01; PM2.5 had a more obvious effect on plant leaf traits than the other PM (p<0.05. Overall, the findings from this study provide useful information regarding the selection of plants to reduce atmospheric pollution.

  7. Fast voxel and polygon ray-tracing algorithms in intensity modulated radiation therapy treatment planning.

    Science.gov (United States)

    Fox, Christopher; Romeijn, H Edwin; Dempsey, James F

    2006-05-01

    We present work on combining three algorithms to improve ray-tracing efficiency in radiation therapy dose computation. The three algorithms include: An improved point-in-polygon algorithm, incremental voxel ray tracing algorithm, and stereographic projection of beamlets for voxel truncation. The point-in-polygon and incremental voxel ray-tracing algorithms have been used in computer graphics and nuclear medicine applications while the stereographic projection algorithm was developed by our group. These algorithms demonstrate significant improvements over the current standard algorithms in peer reviewed literature, i.e., the polygon and voxel ray-tracing algorithms of Siddon for voxel classification (point-in-polygon testing) and dose computation, respectively, and radius testing for voxel truncation. The presented polygon ray-tracing technique was tested on 10 intensity modulated radiation therapy (IMRT) treatment planning cases that required the classification of between 0.58 and 2.0 million voxels on a 2.5 mm isotropic dose grid into 1-4 targets and 5-14 structures represented as extruded polygons (a.k.a. Siddon prisms). Incremental voxel ray tracing and voxel truncation employing virtual stereographic projection was tested on the same IMRT treatment planning cases where voxel dose was required for 230-2400 beamlets using a finite-size pencil-beam algorithm. Between a 100 and 360 fold cpu time improvement over Siddon's method was observed for the polygon ray-tracing algorithm to perform classification of voxels for target and structure membership. Between a 2.6 and 3.1 fold reduction in cpu time over current algorithms was found for the implementation of incremental ray tracing. Additionally, voxel truncation via stereographic projection was observed to be 11-25 times faster than the radial-testing beamlet extent approach and was further improved 1.7-2.0 fold through point-classification using the method of translation over the cross product technique.

  8. Brain size and white matter content of cerebrospinal tracts determine the upper cervical cord area: evidence from structural brain MRI

    Energy Technology Data Exchange (ETDEWEB)

    Engl, Christina; Arsic, Milan; Boucard, Christine C.; Biberacher, Viola; Nunnemann, Sabine; Muehlau, Mark [Technische Universitaet Muenchen, Department of Neurology, Klinikum rechts der Isar, Munich (Germany); Technische Universitaet Muenchen, TUM-Neuroimaging Center, Klinikum rechts der Isar, Munich (Germany); Schmidt, Paul [Technische Universitaet Muenchen, Department of Neurology, Klinikum rechts der Isar, Munich (Germany); Ludwig-Maximilians-University Muenchen, Department of Statistics, Munich (Germany); Roettinger, Michael [Technische Universitaet Muenchen, Department of Radiology, Klinikum rechts der Isar, Munich (Germany); Muenchner Institut fuer Neuroradiologie, Munich (Germany); Etgen, Thorleif [Technische Universitaet Muenchen, Department of Neurology, Klinikum rechts der Isar, Munich (Germany); Klinikum Traunstein, Department of Neurology, Traunstein (Germany); Koutsouleris, Nikolaos; Meisenzahl, Eva M. [Ludwig-Maximilians-Universitaet Muenchen, Department of Psychiatry and Psychotherapy, Munich (Germany); Reiser, Maximilian [Ludwig-Maximilians-Universitaet, Department of Radiology, Munich (Germany)

    2013-08-15

    Measurement of the upper cervical cord area (UCCA) from brain MRI may be an effective way to quantify spinal cord involvement in neurological disorders such as multiple sclerosis. However, knowledge on the determinants of UCCA in healthy controls (HCs) is limited. In two cohorts of 133 and 285 HCs, we studied the influence of different demographic, body-related, and brain-related parameters on UCCA by simple and partial correlation analyses as well as by voxel-based morphometry (VBM) across both cerebral gray matter (GM) and white matter (WM). First, we confirmed the known but moderate effect of age on UCCA in the older cohort. Second, we studied the correlation of UCCA with sex, body height, and total intracranial volume (TIV). TIV was the only variable that correlated significantly with UCCA after correction for the other variables. Third, we studied the correlation of UCCA with brain-related parameters. Brain volume correlated stronger with UCCA than TIV. Both volumes of the brain tissue compartments GM and WM correlated with UCCA significantly. WM volume explained variance of UCCA after correction for GM volume, whilst the opposite was not observed. Correspondingly, VBM did not yield any brain region, whose GM content correlated significantly with UCCA, whilst cerebral WM content of cerebrospinal tracts strongly correlated with UCCA. This latter effect increased along a craniocaudal gradient. UCCA is mainly determined by brain volume as well as by WM content of cerebrospinal tracts. (orig.)

  9. Molecular turnover time of soil organic matter in particle-size fractions of an arable soil.

    Science.gov (United States)

    Bol, Roland; Poirier, Natacha; Balesdent, Jérôme; Gleixner, Gerd

    2009-08-30

    The composition and molecular residence time of soil organic matter (SOM) in four particle-size fractions (POM >200 microm, POM 63-200 microm, silt and clay) were determined using Curie-point pyrolysis/gas chromatography coupled on-line to mass spectrometry. The fractions were isolated from soils, either continuously with a C(3) wheat (soil (13)C value = -26.4 per thousand), or transferred to a C(4) maize (soil (13)C value = -20.2 per thousand) cropping system 23 years ago. Pyrograms contained up to 45 different pyrolysis peaks; 37 (ca. 85%) were identifiable compounds. Lignins and carbohydrates dominated the POM fractions, proteins were abundant, but lignin was (nearly) absent in the silt and clay fractions. The mean turnover time (MRT) for the pyrolysis products in particulate organic matter (POM) was generally <15 years (fast C pool) and 20-300 years (medium or slow C pools) in silt and clay fractions. Methylcyclopentenone (carbohydrate) in the clay fraction and benzene (mixed source) in the silt fraction exhibited the longest MRTs, 297 and 159 years, respectively. Plant-derived organic matter was not stored in soils, but was transformed to microbial remains, mainly in the form of carbohydrates and proteins and held in soil by organo-mineral interactions. Selective preservation of plant-derived OM (i.e. lignin) based on chemical recalcitrance was not observed in these arable soils. Association/presence of C with silt or clays in soils clearly increased MRT values, but in an as yet unresolved manner (i.e. 'truly' stabilized, or potentially still 'labile' but just not accessible C).

  10. Effect of Pot Size on Various Characteristics Related to Photosynthetic Matter Production in Soybean Plants

    Directory of Open Access Journals (Sweden)

    Minobu Kasai

    2012-01-01

    Full Text Available Despite the wide uses of potted plants, information on how pot size affects plant photosynthetic matter production is still considerably limited. This study investigated with soybean plants how transplantation into larger pots affects various characteristics related to photosynthetic matter production. The transplantation was analyzed to increase leaf photosynthetic rate, transpiration rate, and stomatal conductance without affecting significantly leaf intercellular CO2 concentration, implicating that the transplantation induced equal increases in the rate of CO2 diffusion via leaf stomata and the rate of CO2 fixation in leaf photosynthetic cells. Analyses of Rubisco activity and contents of a substrate (ribulose-1,5-bisphosphate (RuBP for Rubisco and total protein in leaf suggested that an increase in leaf Rubisco activity, which is likely to result from an increase in leaf Rubisco content, could contribute to the transplantation-induced increase in leaf photosynthetic rate. Analyses of leaf major photosynthetic carbohydrates and dry weights of source and sink organs revealed that transplantation increased plant sink capacity that uses leaf starch, inducing a decrease in leaf starch content and an increase in whole plant growth, particularly, growth of sink organs. Previously, in the same soybean species, it was demonstrated that negative correlation exists between leaf starch content and photosynthetic rate and that accumulation of starch in leaf decreases the rate of CO2 diffusion within leaf. Thus, it was suggested that the transplantation-induced increase in plant sink capacity decreasing leaf starch content could cause the transplantation-induced increase in leaf photosynthetic rate by inducing an increase in the rate of CO2 diffusion within leaf and thereby substantiating an increase in leaf Rubisco activity in vivo. It was therefore concluded that transplantation of soybean plants into larger pots attempted in this study increased the

  11. Elemental Constituents of Particulate Matter and Newborn's Size in Eight European Cohorts

    DEFF Research Database (Denmark)

    Pedersen, Marie; Gehring, Ulrike; Beelen, Rob

    2016-01-01

    % confidence interval: 1.17, 1.58). Increased nickel and zinc in PM2.5 concentrations were also associated with an increased risk of LBW. Head circumference was reduced at higher exposure to all elements except potassium. All associations with sulfur were most robust to adjustment for PM2.5 mass concentration......BACKGROUND: The health effects of suspended particulate matter (PM) may depend on its chemical composition. Associations between maternal exposure to chemical constituents of PM and newborn's size have been little examined. AIM: We aimed to investigate the associations of exposure to elemental...... cohorts comprising 34,923 singleton births in 1994-2008. Annual average concentrations of elemental constituents of PM smaller than 2.5 and 10 µm (PM2.5 and PM10) at maternal home addresses during pregnancy were estimated using land-use regression models. Adjusted associations between each birth...

  12. Determining consumer purchase intentions: the importance of dry matter, size, and price of kiwifruit.

    Science.gov (United States)

    Jaeger, Sara R; Harker, Roger; Triggs, Chris M; Gunson, Anne; Campbell, Rachel L; Jackman, Richard; Requejo-Jackman, Cecilia

    2011-04-01

    Knowledge of the relative importance of food quality attributes in determining consumer purchase intention is critical for robust assessment of economic opportunities for industry growth. The aim of this study is to demonstrate how conjoint analysis methodology that incorporates tasting of fruit can be used to collect such information. Three hundred Japanese consumers took part in research designed to measure the importance of dry matter (DM), size, and price of kiwifruit (Actinidia deliciosa "Hayward" and Actinidia chinensis "Hort16A") for purchase intention. Measurement of consumer liking for kiwifruit of different DM content was a key first step. Liking increased as DM increased and was accompanied by increased purchase likelihood/choice probability for kiwifruit. The size of kiwifruit presented to consumers varied from "small" to "extra large." Consumers liked "mid-sized" kiwifruit over "small" or "extra-large" kiwifruit. Despite these differences in liking, size was of little importance in determining purchase likelihood/choice probability for kiwifruit. Price was a very important factor in determining purchase likelihood/choice probability but was less important than DM content. As price increased, purchase likelihood/choice probability decreased. Beneath these general findings, heterogeneity existed. Some consumers placed more/less importance on the focal purchase drivers than suggested by the aggregate model. Overall, the results suggest that incentive schemes already implemented by industry should consider rewarding high-DM fruit more than fruit size.   This research has contributed to the New Zealand kiwifruit industry gaining a better understanding of the relative importance consumers place on DM, size, and price of kiwifruit and has resulted in changes to grower incentive schemes. The research approach presented forces consumer to tradeoff attributes of kiwifruit against each other and decide on how important two key quality attributes-DM and

  13. Neuroanatomy of auditory verbal hallucinations in schizophrenia : A quantitative meta-analysis of voxel-based morphometry studies

    NARCIS (Netherlands)

    Modinos, Gemma; Costafreda, Sergi G.; van Tol, Marie-Jose; McGuire, Philip K.; Aleman, Andre; Allen, Paul

    Introduction: Voxel-based morphometry (VBM) studies demonstrate grey matter volume (GMV) deficits in schizophrenia. This method is also applied for detecting associations between specific psychotic symptoms and brain structure, such as auditory verbal hallucinations (AVHs). However, due to differing

  14. Spatial and seasonal variability of particulate matter optical and size properties in the Eastern Mediterranean Sea

    Science.gov (United States)

    Karageorgis, A. P.; Georgopoulos, D.; Kanellopoulos, T. D.; Mikkelsen, O. A.; Pagou, K.; Kontoyiannis, H.; Pavlidou, A.; Anagnostou, Ch.

    2012-12-01

    Particulate matter plays a paramount role in the biogeochemical processes taking place in the marine environment. We report seasonal (spring and summer 2008) distribution of particulate matter in the Eastern Mediterranean, along a transect extending from the open Ionian Sea to the North Aegean Sea, including measurements in the Levantine Sea. A suite of optical instruments measuring beam attenuation (beam cp), fluorescence and particle size, the latter obtained with the innovative in-situ laser particle sizer LISST-Deep are used in concert with traditional measurements of particulate matter concentration (PMC), and total chlorophyll α from bottle samples. PMCs were generally low during both seasons (range: 0.02-0.85 mg L- 1), with values substantially higher in the euphotic zone during spring. The deep waters (> 200 m) in the Eastern Mediterranean exhibit extremely low PMCs, well-below 0.1 mg L- 1. Total chlorophyll α concentrations ranged from 0.003 to 0.28 μg L- 1 in spring and from 0.08 to 0.19 μg L- 1 in summer, verifying the ultra-oligotrophic character of the area. A significant correlation of beam cp and fluorescence in spring suggests that sources of particles are primarily biogenic in the surface waters. Deep water formation triggered the development of a ~ 900-m thick benthic nepheloid layer in the N. Aegean Sea. LISST-Deep revealed valuable information on the particle volume concentrations and the median particle size. It is striking that large particles (range: 31-230 μm; median ~ 85 μm) predominate in the entire region, from the surface up to the deep waters. In addition, accumulation of particles in the pycnocline is observed during summer; however, it is possible that schlieren (increase in beam attenuation due to scattering off of density gradients) could be responsible for the high particle volume concentrations and large median particle diameters recorded. These measurements, conducted for the first time in the Eastern Mediterranean

  15. Preparing a voxel-simulator of Alderson Rando physical phantom

    Energy Technology Data Exchange (ETDEWEB)

    Boia, Leonardo S.; Martins, Maximiano C.; Silva, Ademir X., E-mail: lboia@con.ufrj.br, E-mail: ademir@con.ufrj.br [Programa de Engenharia Nuclear (PEN/COPPE/UFRJ). Universidade Federal do Rio de Janeiro, RJ (Brazil); Salmon Junior, Helio A., E-mail: heliosalmon@coinet.com.br [COI - Clinicas Oncologicas Integradas, MD.X Barra Medical Center, Rio de Janeiro, RJ (Brazil); Soares, Alessandro F.N.S., E-mail: afacure@cnen.gov.br [Comissao Nacional de Engenharia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    There are, nowadays, sorts of anthropomorphycal phantoms which are used for simulation of radiation transport by the matter and also the deposition of energy in such radiation in human tissues and organs, because an in-vitro dosimetry becomes very either complicated or even impossible in some cases. In the present work we prepared a computational phantom in voxels based on computational tomography of Rando-Alderson. This phantom is one of the most known human body simulators on the scope of ionizing radiation dosimetry, and it is used for radioprotection issues and dosimetry from radiotherapy and brachytherapy treatments as well. The preparation of a voxel simulator starts with the image acquisition by a tomograph found at COI/RJ (Clinicas Oncologicas Integradas). The images were generated with 1mm cuts and collected for analysis. After that step the images were processed in SAPDI (Sistema Automatizado de Processamento Digital de Imagem) in order to amplify the images regions intending to facilitate the task in their segmentation. SAPDI is based on parameters described by Hounsfield scale. After that, it has begun discretization of elements in IDs voxels using Scan2MCNP software - which converts images to a sequential text file containing the voxels' IDs ready to be introduced into MCNPX input; however, this set can be turned to a voxel's IDs matrix and used in other Monte Carlo codes, such as Geant4, PENELOPE and EGSnrc. Finished this step, the simulator is able to simulate with accurate geometry the physical phantom. It's possible to study a large number of cases by computational techniques of geometry's insertions of tumors and TLDs, which makes this simulator a research material useful for a lot of subjects. (author)

  16. Rapid three-dimensional quantification of voxel-wise collagen fiber orientation.

    Science.gov (United States)

    Liu, Zhiyi; Quinn, Kyle P; Speroni, Lucia; Arendt, Lisa; Kuperwasser, Charlotte; Sonnenschein, Carlos; Soto, Ana M; Georgakoudi, Irene

    2015-07-01

    Defining fiber orientation at each voxel within a 3D biomedical image stack is potentially useful for a variety of applications, including cancer, wound healing and tissue regeneration. Current methods are typically computationally intensive or inaccurate. Herein, we present a 3D weighted orientation vector summation algorithm, which is a generalization of a previously reported 2D vector summation technique aimed at quantifying collagen fiber orientations simultaneously at each voxel of an image stack. As a result, voxel-wise fiber orientation information with 4° to 5° accuracy can be determined, and the computational time required to analyze a typical stack with the size of 512x512x100 voxels is less than 5 min. Thus, this technique enables the practical extraction of voxel-specific orientation data for characterizing structural anisotropy in 3D specimens. As examples, we use this approach to characterize the fiber organization in an excised mouse mammary gland and a 3D breast tissue model.

  17. Head size may modify the impact of white matter lesions on dementia.

    Science.gov (United States)

    Skoog, Ingmar; Olesen, Pernille J; Blennow, Kaj; Palmertz, Bo; Johnson, Sterling C; Bigler, Erin D

    2012-07-01

    We aimed to examine whether total intracranial volume (TICV), a marker of premorbid brain size, modified the impact of the apolipoprotein E (apoE) e4 phenotype and ischemic white matter lesions (WMLs) on odds for dementia. The study comprised a population-based sample of 104 demented and 135 nondemented 85-year-olds, and included physical and neuropsychiatric examinations, and head computerized tomography (CT). Dementia disorders were defined according to standard criteria. TICV and WMLs were rated on computerized tomography. Using the highest group as reference, the risk for dementia, Alzheimer's disease (AD), and vascular dementia (VaD) was increased in those with the smallest half, tertile, and quartile of TICV. Smaller TICV increased the odds of dementia, Alzheimer's disease, and vascular dementia in participants with WMLs. WMLs were not associated with increased odds of dementia in those with the largest TICV. The interaction term WMLs*TICV was also significant. TICV did not modify the odds of dementia in those with the apolipoprotein e4 phenotype. Our results suggest that the impact of brain pathology on the risk of dementia is modified by premorbid brain size. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Concentration and Size Distribution of Particulate Matter in a Broiler House Ambient Air

    Directory of Open Access Journals (Sweden)

    Ismael Rodrigues Amador

    2016-07-01

    Full Text Available Atmospheric particulate matter (PM is an important constituent of ambient air. The determination of its concentration and size distribution in different environments is essential because of its ability to penetrate deeply into animal and human respiratory tract. In this study, air sampling was performed in a broiler house to estimate the concentration and size distribution of PM emitted along with its activities. Low-vol impactor (< 10 mm, cyclones (< 2.5 e < 1.0 mm, and Sioutas cascade impactor (> 2.5; 1.0 – 2.5; 0.50 – 1.0; 0.25 – 0.50; < 0.25 mm connected with membrane pumps were used. PM10 showed high concentration (209 - 533 mg m-3. PM2.5 and PM1.0 initially showed relatively low concentration (20.8 and 16.0 mg m-3 respectively with significantly increasing levels (412.9 and 344.8 mg m-3 respectively during the samplings. It was also possible to observe the contribution of fine particles. This was evidenced by the high correlation between PM2.5 and PM1.0 and by the profile of particle distribution in the Sioutas sampler. PM concentration levels are considered excessively high, with great potential to affect animal and human health. DOI: http://dx.doi.org/10.17807/orbital.v8i3.847 

  19. Effect of size-fractionation dissolved organic matter on the mobility of prometryne in soil.

    Science.gov (United States)

    Chen, Guang; Lin, Chao; Chen, Liang; Yang, Hong

    2010-05-01

    Import of organic materials in the form of compost, sludge or plant residues introduces large amounts of dissolved organic matter (DOM) into soils. DOM as a dynamic soil component affects the behaviors of organic pollutants. Different DOM constituents may affect herbicide action in a different way. However, the process of interaction between the distinct DOM-fractions and herbicides is largely unknown. In this study, DOM was separated by size-fractionation into three molecular size groups: MW14000 Da. Effects of DOM-fractions on prometryne sorption/desorption and mobility were analyzed using approaches of batch experiments, soil column and soil thin-layer chromatography. Application of varied DOM-fractions at 50mg DOCL(-1) to the soil reduced the sorption and increased desorption of prometryne. DOM-fraction with MW>14000 Da appeared most effective in prometryne mobilization in the soil than any other fractions. Finally, DOM-fractions were characterized by chemical analyses, fourier transformed infrared spectroscopy (FT-IR) and excitation-emission matrices (EEMs) fluorescence spectroscopy. Our studies revealed that the high-molecular weight fraction contained more aromatic framework and unsaturated structure that was most likely the dominant factor modulating the behavior of prometryne in soils.

  20. Size and composition distributions of particulate matter emissions: part 1--light-duty gasoline vehicles.

    Science.gov (United States)

    Robert, Michael A; VanBergen, Saskia; Kleeman, Michael J; Jakober, Christopher A

    2007-12-01

    Size-resolved particulate matter (PM) emitted from light-duty gasoline vehicles (LDGVs) was characterized using filter-based samplers, cascade impactors, and scanning mobility particle size measurements in the summer 2002. Thirty LDGVs, with different engine and emissions control technologies (model years 1965-2003; odometer readings 1264-207,104 mi), were tested on a chassis dynamometer using the federal test procedure (FTP), the unified cycle (UC), and the correction cycle (CC). LDGV PM emissions were strongly correlated with vehicle age and emissions control technology. The oldest models had average ultrafine PM0.1 (0.056- to 0.1-microm aerodynamic diameter) and fine PM1.8 (emission rates of 9.6 mg/km and 213 mg/km, respectively. The newest vehicles had PM0.1 and PM1.8 emissions of 51 microg/km and 371 microg/km, respectively. Light duty trucks and sport utility vehicles had PM0.1 and PM1.8 emissions nearly double the corresponding emission rates from passenger cars. Higher PM emissions were associated with cold starts and hard accelerations. The FTP driving cycle produced the lowest emissions, followed by the UC and the CC. PM mass distributions peaked between 0.1- and 0.18-microm particle diameter for all vehicles except those emitting visible smoke, which peaked between 0.18 and 0.32 microm. The majority of the PM was composed of carbonaceous material, with only trace amounts of water-soluble ions. Elemental carbon (EC) and organic matter (OM) had similar size distributions, but the EC/OM ratio in LDGV exhaust particles was a strong function of the adopted emissions control technology and of vehicle maintenance. Exhaust from LDGV classes with lower PM emissions generally had higher EC/OM ratios. LDGVs adopting newer technologies were characterized by the highest EC/OM ratios, whereas OM dominated PM emissions from older vehicles. Driving cycles with cold starts and hard accelerations produced higher EC/OM ratios in ultrafine particles.

  1. 采用基于体素的形态测量学比较分析不同核型特纳综合征患儿全脑灰质的变化%Comparison of gray matter among children with different karyotype of Turner syndrome: voxel-based morphometry analysis

    Institute of Scientific and Technical Information of China (English)

    谢晟; 赵秋玲; 张知新; 刘茜玮; 张嘉颖; 龚高浪

    2013-01-01

    Objective To detect the difference of cerebral gray matter change in children with different karyotype Turner Syndrome (TS) by using voxel-based morphometry (VBM).Methods Nineteen children with 45XO karyotype TS,21 children with heterozygous TS and 20 age-matched control girls were recruited in this study.Wechsler intelligence scale for children was used to obtain their intelligence quotients (IQ).High-resolution magnetic MR imaging was performed in TS children and control girls to collect the whole brain structural data.The data was analyzed by VBM based on SPM8 to compare the volume of gray matter among the monosomy TS children,heterozygous TS children and normal controls by using covariance analysis.Alphasim method in the software of analysis of functional neuroimages(AFNI) was used for clusterlevel multiple comparison.Results The IQ was 89 ± 16 for the monosomy TS children,and it was 91 ± 13 for heterozygous TS children and 109 ± 15 for the controls.Statistical analysis revealed significant difference of IQ among them (F =10.75,P < 0.05).Compared with normal controls,both monosomy TS children and heterozygous TS children showed significantly decreased volume (voxel numbers in clusters were 4117,1392,1085,t =5.75,5.33 and 5.02 for monosomy TS; voxel numbers in clusters were 4501,2437,591,t =5.40,5.11 and 4.95 for heterozygous TS respectively,P < 0.01,FWE-corrected) in the gray matter of bilateral precuneus lobule,postcentral gyrus,and cingulum cortex.However,the volume of the orbitofrontal lobe,parahippocampal gyrus,cerebellum,temporal pole,corpus striatum and posterior midbrain were increased in the monosomy and heterozygous TS children compared to the controls (voxel numbers in clusters were 1444,1188,791,725,695,431,386,t =5.01,5.96,5.67,5.23,4.85,4.43,4.94 for monosomy TS; voxel numbers in clusters were 6988,2709,2510,2380,1987,1709,1185,t =6.50,7.06,7.26,5.27,5.71,6.02,4.56 for heterozygous TS,P < 0.01,FWE-corrected).Compared with monosomy TS

  2. Relationship between ventricular size, white matter injury, and neurocognition in children with stable, treated hydrocephalus.

    Science.gov (United States)

    Kulkarni, Abhaya V; Donnelly, Ruth; Mabbott, Donald J; Widjaja, Elysa

    2015-09-01

    Larger-than-normal ventricles can persist in children following hydrocephalus treatment, even if they are asymptomatic and clinically well. This study aims to answer the following question: do large ventricles result in brain injuries that are detectable on diffusion tensor imaging (DTI) and/or in measurable neurocognitive deficits in children with stable, treated hydrocephalus that are not seen in children with small ventricles? For this prospective study, we recruited 23 children (age range 8-18 years) with hydrocephalus due to aqueductal stenosis or tectal glioma who were asymptomatic following hydrocephalus treatment that had been performed at least 2 years earlier. All patients underwent detailed DTI and a full battery of neuropsychological tests. Correlation analysis was performed to assess the relationship between DTI parameters, neurocognitive tests, and ventricular size. The false-discovery rate method was used to adjust for multiple comparisons. The median age of these 23 children at the time of assessment was 15.0 years (interquartile range [IQR] 12.1-17.6 years), and the median age at the first hydrocephalus treatment was 5.8 years (IQR 2.2 months-12.8 years). At the time of assessment, 17 children had undergone endoscopic third ventriculostomy and 6 children had received a shunt. After adjusting for multiple comparisons, there were no significant correlations between any neurocognitive test and ventricular volume, any DTI parameter and ventricular volume, or any DTI parameter and neurocognitive test. Our data do not show an association between large ventricular size and additional white matter injury or worse neurocognitive deficits in asymptomatic children with stable, treated hydrocephalus caused by a discrete blockage of the cerebral aqueduct. Further investigations using larger patient samples are needed to validate these results.

  3. Molecular Composition and Photochemical Reactivity of Size-Fractionated Dissolved Organic Matter.

    Science.gov (United States)

    Maizel, Andrew C; Remucal, Christina K

    2017-02-21

    The photochemical production of reactive species, such as triplet dissolved organic matter ((3)DOM) and singlet oxygen ((1)O2), contributes to the degradation of aquatic contaminants and is related to an array of DOM structural characteristics, notably molecular weight. In order to relate DOM molecular weight, optical properties, and reactive species production, Suwannee River (SRFA) and Pony Lake fulvic acid (PLFA) isolates are fractionated by sequential ultrafiltration, and the resultant fractions are evaluated in terms of molecular composition and photochemical reactivity. UV-visible measurements of aromaticity increase with molecular weight in both fulvic acids, while PLFA molecular weight fractions are shown to be structurally similar by Fourier-transform ion cyclotron resonance mass spectrometry. In addition, Bray-Curtis dissimilarity analysis of formulas identified in the isolates and their size fractions reveal that SRFA and PLFA have distinct molecular compositions. Quantum yields of (3)DOM, measured by electron and energy transfer probes, and (1)O2 decreased with molecular weight. Decreasing [(3)DOM]ss with molecular weight is shown to derive from elevated quenching in high molecular weight fractions, rather than increased (3)DOM formation. This work has implications for the photochemistry of waters undergoing natural or engineered treatment processes that alter DOM molecular weight, such as photooxidation and biological degradation.

  4. 基于体素的遗忘型轻度认知障碍和轻度阿尔茨海默病全脑白质MR扩散张量成像分析%MR diffusion tensor imaging voxel-based analysis of whole brain white matter in patients with amnestic-type mild cognitive impairment and mild Alzheimer disease

    Institute of Scientific and Technical Information of China (English)

    李亚迪; 冯晓源; 何慧瑾; 丁玎; 汤伟军; 赵倩华

    2011-01-01

    microstructural integrity of white matter (WM) in patients with amnestic mild cognitive impairment (aMCI) and mild Alzheimer's disease (AD) using voxel-based analysis (VBA), and investigate the relationship between WM abnormalities and gray matter(GM) atrophy.Methods Thirty-three cases with aMCI, 32 cases with mild AD and 31 normal aging volunteers as control subjects were scanned on a 3.0 T MR system using diffusion tensor imaging (DTI) and three-dimensional spoiled gradient-recalled(3DSPGR) sequences. Fractional anisotropy (FA) maps and morphological images were preprocessed by SPM5 and voxel-based comparisons between the 2 patient groups and the control group were performed by t test. Results Relative to the control group, patients with aMCI showed significantly reduced FA value in bilateral frontal, temporal and left occipital WM, left anterior part of cingulum, left inferior parietal lobule, and the W M adjacent to the triangular part of the right lateral ventricle(k≥20 voxels).In mild AD,significantly reduced FA value was found in bilateral hippocampal,inferior parietal lobular,frontal,temporal,and occipital WM,bilateral corpus callosum,anterior part of cingulums,the WM adjacent to the triaangular part of the bilateral lateral ventricles,left temporal stem,left thalamus,right precuneus(k≥20 voxels).Significantly reduced GM volume was found in left hippocampus,parahippocampal gyrus,lingual gyrus and superior temporal gyrus,bilateral insulae and middle temporal gyri in aMCl group whencompared with control group(k≥50 voxels).In mild AD,significantly reduced GM volume was found in bilateral hippoeampi,parahippocampal gyri,amygdalae,thalami,temporal,parietal,frontal,occipital cortex(k≥50 voxels).The pattern of areas with reduced FA differs;from that of the GM volumetric reduction.No areas with significantlv reduced FA was detected in aMCl compared with mild AD. There was no significant correlation between FA value of WM in patient groups and Mini-Mental State Examination

  5. Comparing voxel-based iterative sensitivity and voxel-based morphometry to detect abnormalities in T2-weighted MRI.

    Science.gov (United States)

    Diaz-de-Grenu, Lara Z; Acosta-Cabronero, Julio; Williams, Guy B; Nestor, Peter J

    2014-10-15

    This study aimed to test the superiority proposed by Abbott et al. (2011) of their Voxel based iterative sensitivity (VBIS) method over Voxel Based Morphometry using T2-weighted images (T2-VBM), in detecting intensity changes in Alzheimer's disease (AD). A comparison was made first in simulated intensity lesions and then in AD patients. Intensity changes were evaluated in the whole-brain with VBIS and with a simple intensity-based approach and in specific tissue classes with the conventional VBM method of using tissue probability segments. Results showed that VBIS performed well in the simulated environment though it showed no superiority in detecting the lesion compared to the much simpler VBM approach. The VBIS method, however, failed to detect any meaningful signal intensity reduction in AD patient data. Moreover, its whole brain approach was contaminated by the excess cerebrospinal fluid signal (very bright on T2-weighted scans) in areas of maximal measurable atrophy (mesial temporal lobes); this gave rise to spurious signal intensity increases in these regions in AD. The same artefact was observed for both intensity-based methods but not with the conventional VBM approach of performing statistics on grey matter segments. In conclusion, no evidence was found to indicate that VBIS offers benefits over T2-VBM in AD, nor in simulation intensity lesions. The study highlights the necessity of empirically testing voxel-based analysis techniques rather than merely claiming superiority of one method over another on theoretical grounds.

  6. Voxel inversion of airborne EM data

    DEFF Research Database (Denmark)

    Fiandaca, Gianluca G.; Auken, Esben; Christiansen, Anders Vest C A.V.C.;

    2013-01-01

    We present a geophysical inversion algorithm working directly in a voxel grid disconnected from the actual measuring points, which allows for straightforward integration of different data types in joint inversion, for informing geological/hydrogeological models directly and for easier incorporation...... for jointly inverting airborne and ground-based geophysical data. Furthermore, geological and groundwater models most often refer to a regular voxel grid not correlated to the geophysical model space, and incorporating the geophysical data into the geological/hydrological modelling grids is problematic. We...... present a voxel grid inversion routine that overcomes these problems and we discuss in detail the algorithm implementation....

  7. VoxelStats: A MATLAB Package for Multi-Modal Voxel-Wise Brain Image Analysis.

    Science.gov (United States)

    Mathotaarachchi, Sulantha; Wang, Seqian; Shin, Monica; Pascoal, Tharick A; Benedet, Andrea L; Kang, Min Su; Beaudry, Thomas; Fonov, Vladimir S; Gauthier, Serge; Labbe, Aurélie; Rosa-Neto, Pedro

    2016-01-01

    In healthy individuals, behavioral outcomes are highly associated with the variability on brain regional structure or neurochemical phenotypes. Similarly, in the context of neurodegenerative conditions, neuroimaging reveals that cognitive decline is linked to the magnitude of atrophy, neurochemical declines, or concentrations of abnormal protein aggregates across brain regions. However, modeling the effects of multiple regional abnormalities as determinants of cognitive decline at the voxel level remains largely unexplored by multimodal imaging research, given the high computational cost of estimating regression models for every single voxel from various imaging modalities. VoxelStats is a voxel-wise computational framework to overcome these computational limitations and to perform statistical operations on multiple scalar variables and imaging modalities at the voxel level. VoxelStats package has been developed in Matlab(®) and supports imaging formats such as Nifti-1, ANALYZE, and MINC v2. Prebuilt functions in VoxelStats enable the user to perform voxel-wise general and generalized linear models and mixed effect models with multiple volumetric covariates. Importantly, VoxelStats can recognize scalar values or image volumes as response variables and can accommodate volumetric statistical covariates as well as their interaction effects with other variables. Furthermore, this package includes built-in functionality to perform voxel-wise receiver operating characteristic analysis and paired and unpaired group contrast analysis. Validation of VoxelStats was conducted by comparing the linear regression functionality with existing toolboxes such as glim_image and RMINC. The validation results were identical to existing methods and the additional functionality was demonstrated by generating feature case assessments (t-statistics, odds ratio, and true positive rate maps). In summary, VoxelStats expands the current methods for multimodal imaging analysis by allowing the

  8. Temporal patterns of dissolved organic matter biodegradability are similar across three rivers of varying size

    Science.gov (United States)

    Coble, Ashley A.; Marcarelli, Amy M.; Kane, Evan S.; Toczydlowski, David; Stottlemyer, Robert

    2016-06-01

    Dissolved organic matter (DOM) composition may be an important determinant of its fate in freshwaters, but little is known about temporal variability in DOM composition and the biodegradability of DOM in northern temperate watersheds. We measured biodegradable dissolved organic carbon (BDOC) via incubation assays and DOM composition using optical indices on 11 dates in three Lake Superior tributaries. Percent BDOC (%BDOC) and BDOC concentrations were seasonally synchronous across these watersheds, despite that they vary in size by orders of magnitude (1.7 to 3400 km2). Relative to %BDOC, BDOC concentrations were more tightly constrained among sites on any given date. BDOC also varied within seasons; for example, %BDOC on two different dates in winter were among the highest (29% and 54%) and lowest (0%) values observed for each site (overall %BDOC range: 0 to 72%). DOM composition varied the most among tributaries during a summer storm event when BDOC (both as percent and concentration) was elevated but was remarkably similar among tributaries during fall, spring, and winter. Multivariate models identified humic-like and tryptophan-like fluorophores as predictors of %BDOC, but DOM composition only described 21% of the overall variation in %BDOC. Collectively, these three rivers exported ~18 Gg C yr-1 as DOC and ~2 Gg C yr-1 as BDOC, which corresponded to 9 to 17% of annual DOC exported in biodegradable form. Our results suggest much of the C exported from these northern temperate watersheds may be biodegradable within 28 days and that large pulses of labile DOM can be exported during storm events and spring snowmelt.

  9. Towards a simple and sensitive size-density fractionation approach for determining changes in soil organic matter

    Science.gov (United States)

    Guidi, Claudia; Magid, Jakob; Rodeghiero, Mirco

    2017-04-01

    Fractionation of soil organic matter (SOM), i.e. the separation of SOM into discrete fractions, can elucidate the temporal responses of soil organic carbon (SOC) to land-use and management changes. In order to reduce the workload and uncertainties associated with fractionation, we optimized and tested a simple size-density fractionation approach, containing a limited number of fractions and using relatively mild soil dispersion. We compared size-density fractionation, which isolated non-occluded particulate organic matter (POM), stable aggregates and silt- and clay-sized fraction, with aggregate size fractionation, i.e. an established method for aggregate separation, and with SOC content in the bulk soil. These methods were tested on soil samples collected from the mineral soil (0-20 cm) of a land-use and management gradient examining forest colonization on grassland in the Southern Alps (Italy). Differences in SOC stocks among successional stages were detected both by size-density fractions, aggregate size fractions and SOC content in the bulk soil. However, size-density fractions were better suited than aggregate size fractions for the detection of changes in SOC allocation within the study area. Therefore, the tested size-density fractionation approach may be preferred over aggregate size fractionation, considering its higher sensitivity to SOC differences in the land-use gradient. Stable aggregates obtained by size-density fractionation detected both changes in SOC allocation and stocks, and have the potential to be used as indicators of SOC changes in soils that express aggregate hierarchy. Further testing of the developed procedure across soil types, environmental conditions and land uses is required to confirm its repeatability and sensitivity to SOC changes.

  10. Cytotoxicity and genotoxicity induced in vitro by solvent-extractable organic matter of size-segregated urban particulate matter.

    Science.gov (United States)

    Velali, Ekaterini; Papachristou, Eleni; Pantazaki, Anastasia; Choli-Papadopoulou, Theodora; Argyrou, Nikoleta; Tsourouktsoglou, Theodora; Lialiaris, Stergios; Constantinidis, Alexandros; Lykidis, Dimitrios; Lialiaris, Thedore S; Besis, Athanasios; Voutsa, Dimitra; Samara, Constantini

    2016-11-01

    Three organic fractions of different polarity, including a non polar organic fraction (NPOF), a moderately polar organic fraction (MPOF), and a polar organic fraction (POF) were obtained from size-segregated (3 μm) urban particulate matter (PM) samples, and tested for cytotoxicity and genotoxicity using a battery of in vitro assays. The cytotoxicity induced by the organic PM fractions was measured by the mitochondrial dehydrogenase (MTT) cell viability assay applied on MRC-5 human lung epithelial cells. DNA damages were evaluated through the comet assay, determination of the poly(ADP-Ribose) polymerase (PARP) activity, and the oxidative DNA adduct 8-hydroxy-deoxyguanosine (8-OHdG) formation, while pro-inflammatory effects were assessed by determination of the tumor necrosis factor-alpha (TNF-α) mediator release. In addition, the Sister Chromatid Exchange (SCE) inducibility of the solvent-extractable organic matter was measured on human peripheral lymphocyte. Variations of responses were assessed in relation to the polarity (hence the expected composition) of the organic PM fractions, particle size, locality, and season. Organic PM fractions were found to induce rather comparable Cytotoxicity and genotoxicity of PM appeared to be rather independent from the polarity of the extractable organic PM matter (EOM) with POF often being relatively more toxic than NPOF or MPOF. All assays indicated stronger mass-normalized bioactivity for fine than coarse particles peaking in the 0.97-3 and/or the 0.49-0.97 μm size ranges. Nevertheless, the air volume-normalized bioactivity in all assays was highest for the size range highlighting the important human health risk posed by the inhalation of these quasi-ultrafine particles. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Mapping the MRI voxel volume in which thermal noise matches physiological noise--implications for fMRI.

    Science.gov (United States)

    Bodurka, J; Ye, F; Petridou, N; Murphy, K; Bandettini, P A

    2007-01-15

    This work addresses the choice of the imaging voxel volume in blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI). Noise of physiological origin that is present in the voxel time course is a prohibitive factor in the detection of small activation-induced BOLD signal changes. If the physiological noise contribution dominates over the temporal fluctuation contribution in the imaging voxel, further increases in the voxel signal-to-noise ratio (SNR) will have diminished corresponding increases in temporal signal-to-noise (TSNR), resulting in reduced corresponding increases in the ability to detect activation induced signal changes. On the other hand, if the thermal and system noise dominate (suggesting a relatively low SNR) further decreases in SNR can prohibit detection of activation-induced signal changes. Here we have proposed and called the "suggested" voxel volume for fMRI the volume where thermal plus system-related and physiological noise variances are equal. Based on this condition we have created maps of fMRI suggested voxel volume from our experimental data at 3T, since this value will spatially vary depending on the contribution of physiologic noise in each voxel. Based on our fast EPI segmentation technique we have found that for gray matter (GM), white matter (WM), and cerebral spinal fluid (CSF) brain compartments the mean suggested cubical voxel volume is: (1.8 mm)3, (2.1 mm)3 and (1.4 mm)3, respectively. Serendipitously, (1.8 mm)3 cubical voxel volume for GM approximately matches the cortical thickness, thus optimizing BOLD contrast by minimizing partial volume averaging. The introduced suggested fMRI voxel volume can be a useful parameter for choice of imaging volume for functional studies.

  12. Does size matter? An investigation of how department size and other organizational variables influence on publication productivity and citation impact

    Energy Technology Data Exchange (ETDEWEB)

    Aksnes, D.W.; Rørstad, K.; Piro, F.N.

    2016-07-01

    In this study, we investigate whether university department size is important in determining publication productivity and citation impact. Drawing on a unique dataset containing a variety of different variables at department levels, we are able to provide a richer picture of the research performance than what typically has been the case in many previous studies. In addition to analyzing the basic question of how size relates to scientific performance, we address whether the funding profile of the departments plays a role, whether the scientific performance is influenced by the composition of the academic personnel (in terms of gender, academic positions, recruiting personnel and the share of doctoral degree holders). The study shows that virtually no size effect can be identified and highly productive and highly cited units are found among both small, medium and large departments. For none of the organizational variables we are able to identify statistically significant relationships in respect to research performance at an overall level. We conclude that the productivity and citation differences at the level of departments cannot generally be explained by the selected variables for department size, funding structure and the composition of scientific personnel. (Author)

  13. Size matters: relationships between body size and body mass of common coastal, aquatic invertebrates in the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Johan Eklöf

    2017-01-01

    Full Text Available Background Organism biomass is one of the most important variables in ecological studies, making biomass estimations one of the most common laboratory tasks. Biomass of small macroinvertebrates is usually estimated as dry mass or ash-free dry mass (hereafter ‘DM’ vs. ‘AFDM’ per sample; a laborious and time consuming process, that often can be speeded up using easily measured and reliable proxy variables like body size or wet (fresh mass. Another common way of estimating AFDM (one of the most accurate but also time-consuming estimates of biologically active tissue mass is the use of AFDM/DM ratios as conversion factors. So far, however, these ratios typically ignore the possibility that the relative mass of biologically active vs. non-active support tissue (e.g., protective exoskeleton or shell—and therefore, also AFDM/DM ratios—may change with body size, as previously shown for taxa like spiders, vertebrates and trees. Methods We collected aquatic, epibenthic macroinvertebrates (>1 mm in 32 shallow bays along a 360 km stretch of the Swedish coast along the Baltic Sea; one of the largest brackish water bodies on Earth. We then estimated statistical relationships between the body size (length or height in mm, body dry mass and ash-free dry mass for 14 of the most common taxa; five gastropods, three bivalves, three crustaceans and three insect larvae. Finally, we statistically estimated the potential influence of body size on the AFDM/DM ratio per taxon. Results For most taxa, non-linear regression models describing the power relationship between body size and (i DM and (ii AFDM fit the data well (as indicated by low SE and high R2. Moreover, for more than half of the taxa studied (including the vast majority of the shelled molluscs, body size had a negative influence on organism AFDM/DM ratios. Discussion The good fit of the modelled power relationships suggests that the constants reported here can be used to quickly estimate

  14. 单体型特纳综合征患儿全脑灰、白质基于体素的形态学分析%A whole-brain gray and white matter analysis in children with 45XO karyotype Turner syndrome:voxel-based morphometry

    Institute of Scientific and Technical Information of China (English)

    赵秋玲; 谢晟; 张知新; 潘慧; 李康; 张嘉颖; 程盼贵; 龚高浪; 刘茜玮

    2013-01-01

    Objective To detect the structural changes of cerebral gray and white matter in children of monosomy Turner syndrome (TS) by using voxel-based morphometry (VBM).Methods Nine children 45XO karyotype TS and 20 age-matched control girls were recruited in this study.Wechsler intelligence scale for children was used to obtain their intelligence quotients (IQ).High-resolution magnetic MR imaging was performed in TS children and control girls to collect the whole brain structural data.The data were analyzed by VBM based on SPM 8 to compare the volume of gray and white matter between the TS children and normal controls by using covariance analysis.Results The IQ of TS children was 81 ± 13,and the IQ of the controls was 109 ± 16.Statistical analysis revealed significant difference of IQ between the two groups (t =-4.70,P < 0.05).Compared with normal controls,TS children showed significantly decreased volume (numbers of voxel in clusters were 631,525,520,t =3.95,3.50,3.36,P < 0.05,FWE-corrected) in the gray matter of the right superior parietal lobule,postcentral gyrus,precuneus lobule,calcarine,cuneus cortices,as well as the left middle and inferior occipital lobe.However,the volume of the bilateral supplemental motor area and the medial superior frontal lobes,the right middle cingulum,the left superior,middle,and inferior temporal gyri were increased in the TS children compared to the controls.The left fusiform,the left parahippocampus,the left hippocampus and the left cerebellum were also enlarged in TS children (numbers of voxel in clusters were 2082,974,1708,588,579,t =5.45,4.59,4.40,4.29,3.55,P <0.05,FWE-corrected).White matter regions in the left postcentral gyrus and inferior parietal lobule showed significantly reduced volume (voxel number 957,t =5.85,P < 0.05,FWE-corrected).Conclusion Children with monosomy TS show abnormal gray and white matter volumes in some brain regions,which may be involved in the neuropathology of Turner syndrome.%目的 利用

  15. Mild cognitive impairment in patients with Parkinson's disease: A voxel-based morphometry analysis of gray matter%帕金森病轻度认知功能障碍:基于体素的全脑灰质形态学研究

    Institute of Scientific and Technical Information of China (English)

    胡晓飞; 张久权; 张艳玲; 吴娅; 陈利华; 王健

    2013-01-01

    目的 采用基于体素的形态学测量方法,分析帕金森病(PD)伴轻度认知功能损害(MCI)患者全脑灰质结构的变化.方法 利用3.0T MR仪对22例伴MCI的PD患者(PD伴MCI组)、21例认知功能正常的PD患者(单纯PD组)及20名健康对照(NC组)进行T1W扫描.采用SPM8为基础的VBM8工具箱进行数据处理.结果 与NC组比较,PD伴MCI组脑灰质萎缩见于双侧额叶、左侧颞叶、双侧枕叶、双侧小脑、左侧后扣带回及左侧海马区域;单纯PD组脑灰质萎缩集中出现于左侧额叶、颞叶.与单纯PD组相比,PD伴MCI组左侧颞中回和海马旁回出现灰质萎缩.结论 伴有MCI的PD患者的脑灰质结构改变范围比不伴MCI者更广,提示PD患者认知功能改变存在脑形态结构水平的异常.%Objective To investigate the changes of grey matter in Parkinson's disease (PD) patients with mild cognitive impairment (MCI) using voxel-based morphometry (VBM). Methods Totally 43 PD patients were classified using cognitive testing as PD with normal cognition (single PD, n = 21) and PD with MCI (PD-MCI, n=22). And 20 normal controls were enrolled (NC). T1WI were derived using a 3. 0T MR scanner. The differences of grey matter volumes were evaluated using VBM. Results Compared with NC, PD-MCI exhibited reduced grey matter volume in bilateral frontal cortex, bilateral cerebellum, the right occipital lobe, as well as in left temporal lobe, posterior cingulate and the hippocampus. Patients with single PD showed limited grey matter atrophy in the left temporal and frontal cortex. Compared with single PD patients, areas of grey matter in the left middle temporal gyrus and parahippocampal reduced in PD-MCI patients. Conclusion PD with MCI is associated with structural neocortical changes in the brain, suggesting that there may exist a gradient of neuropathology structures in PD.

  16. A free database of radionuclide voxel S values for the dosimetry of nonuniform activity distributions

    Science.gov (United States)

    Lanconelli, N.; Pacilio, M.; Lo Meo, S.; Botta, F.; Di Dia, A.; Torres Aroche, L. A.; Coca Pérez, M. A.; Cremonesi, M.

    2012-01-01

    The increasing availability of SPECT/CT devices with advanced technology offers the opportunity for the accurate assessment of the radiation dose to the biological target volume during radionuclide therapy. Voxel dosimetry can be performed employing direct Monte Carlo radiation transport simulations, based on both morphological and functional images of the patient. On the other hand, for voxel dosimetry calculations the voxel S value method can be considered an easier approach than patient-specific Monte Carlo simulations, ensuring a good dosimetric accuracy at least for anatomic regions which are characterized by uniform density tissue. However, this approach has been limited because of the lack of tabulated S values for different voxel dimensions and radionuclides. The aim of this work is to provide a free dataset of values which can be used for voxel dosimetry in targeted radionuclide studies. Seven different radionuclides (89Sr, 90Y, 131I, 153Sm, 177Lu, 186Re, 188Re), and 13 different voxel sizes (2.21, 2.33, 2.4, 3, 3.59, 3.9, 4, 4.42, 4.8, 5, 6, 6.8 and 9.28 mm) are considered. Voxel S values are calculated performing simulations of monochromatic photon and electron sources in two different homogeneous tissues (soft tissue and bone) with DOSXYZnrc code, and weighting the contributions on the basis of the radionuclide emission spectra. The outcomes are validated by comparison with Monte Carlo simulations obtained with other codes (PENELOPE and MCNP4c) performing direct simulation of the radionuclide emission spectra. The differences among the different Monte Carlo codes are of the order of a few per cent when considering the source voxel and the bremsstrahlung tail, whereas the highest differences are observed at a distance close to the maximum continuous slowing down approximation range of electrons. These discrepancies would negligibly affect dosimetric assessments. The dataset of voxel S values can be freely downloaded from the website www.medphys.it.

  17. A free database of radionuclide voxel S values for the dosimetry of nonuniform activity distributions.

    Science.gov (United States)

    Lanconelli, N; Pacilio, M; Lo Meo, S; Botta, F; Di Dia, A; Aroche, A Torres; Pérez, M A Coca; Cremonesi, M

    2012-01-21

    The increasing availability of SPECT/CT devices with advanced technology offers the opportunity for the accurate assessment of the radiation dose to the biological target volume during radionuclide therapy. Voxel dosimetry can be performed employing direct Monte Carlo radiation transport simulations, based on both morphological and functional images of the patient. On the other hand, for voxel dosimetry calculations the voxel S value method can be considered an easier approach than patient-specific Monte Carlo simulations, ensuring a good dosimetric accuracy at least for anatomic regions which are characterized by uniform density tissue. However, this approach has been limited because of the lack of tabulated S values for different voxel dimensions and radionuclides. The aim of this work is to provide a free dataset of values which can be used for voxel dosimetry in targeted radionuclide studies. Seven different radionuclides (89Sr, 90Y, 131I, 153Sm, 177Lu, 186Re, 188Re), and 13 different voxel sizes (2.21, 2.33, 2.4, 3, 3.59, 3.9, 4, 4.42, 4.8, 5, 6, 6.8 and 9.28 mm) are considered. Voxel S values are calculated performing simulations of monochromatic photon and electron sources in two different homogeneous tissues (soft tissue and bone) with DOSXYZnrc code, and weighting the contributions on the basis of the radionuclide emission spectra. The outcomes are validated by comparison with Monte Carlo simulations obtained with other codes (PENELOPE and MCNP4c) performing direct simulation of the radionuclide emission spectra. The differences among the different Monte Carlo codes are of the order of a few per cent when considering the source voxel and the bremsstrahlung tail, whereas the highest differences are observed at a distance close to the maximum continuous slowing down approximation range of electrons. These discrepancies would negligibly affect dosimetric assessments. The dataset of voxel S values can be freely downloaded from the website www.medphys.it.

  18. Carbohydrates in size fractionated dissolved organic matter in a station of the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, L.; DeSouza, F.; Bhosle, N.B.

    of the dissolved organic matter (DOM) were collected using Amicon stirred Ultrafiltration Cell, and analysed for dissolved organic carbon (UDOC), total carbohydrates (UTCHO) and neutral sugars (UNS). UDOC concentrations were relatively higher in HMW fraction...

  19. Influence of different weather events on concentrations of particulate matter with different sizes in Lanzhou, China

    Institute of Scientific and Technical Information of China (English)

    Xinyuan Feng; Shigong Wang

    2012-01-01

    The formation and development of weather events has a great impact on the diffusion,accumulation and transport of air pollutants,and causes great changes in the particulate pollution level.It is very important to study their influence on particulate pollution.Lanzhou is one of the most particulate-polluted cities in China and even in the world.Particulate matter (PM) including TSP,PM>10,PM2.5-10,PM2.5 and PM1.0 concentrations were simultaneously measured during 2005-2007 in Lanzhou to evaluate the influence of three kinds of weather events - dust,precipitation and cold front - on the concentrations of PM with different sizes and detect the temporal evolution.The main results are as follows:(1) the PM pollution in Lanzhou during dust events was very heavy and the rate of increase in the concentration of PM2.5-10 was the highest of the five kinds of particles.During dust-storm events,the highest peaks of the concentrations of fine particles (PM2.5 and PM1.0) occurred 3 hr later than those of coarse particles (PM>10 and PM2.5-10).(2) The major effect of precipitation events on PM is wet scavenging.The scavenging rates of particles were closely associated with the kinds of precipitation events.The scavenging rates of TSP,PM>10 and PM2.5-10 by convective precipitation were several times as high as those caused by frontal precipitation for the same precipitation amount,the reason being the different formation mechanism and precipitation characteristics of the two kinds of precipitation.Moreover,there exists a limiting value for the scavenging rates of particles by precipitation.(3) The major effect of cold-front events on particles is clearance.However,during cold-front passages,the PM concentrations could sometimes rise first and decrease afterwards,which is the critical difference in the influence of cold fronts on the concentrations of particulate pollutants vs.gaseous pollutants.

  20. Correlation between white matter damage and gray matter lesions in multiple sclerosis patients

    Directory of Open Access Journals (Sweden)

    Xue-mei Han

    2017-01-01

    Full Text Available We observed the characteristics of white matter fibers and gray matter in multiple sclerosis patients, to identify changes in diffusion tensor imaging fractional anisotropy values following white matter fiber injury. We analyzed the correlation between fractional anisotropy values and changes in whole-brain gray matter volume. The participants included 20 patients with relapsing-remitting multiple sclerosis and 20 healthy volunteers as controls. All subjects underwent head magnetic resonance imaging and diffusion tensor imaging. Our results revealed that fractional anisotropy values decreased and gray matter volumes were reduced in the genu and splenium of corpus callosum, left anterior thalamic radiation, hippocampus, uncinate fasciculus, right corticospinal tract, bilateral cingulate gyri, and inferior longitudinal fasciculus in multiple sclerosis patients. Gray matter volumes were significantly different between the two groups in the right frontal lobe (superior frontal, middle frontal, precentral, and orbital gyri, right parietal lobe (postcentral and inferior parietal gyri, right temporal lobe (caudate nucleus, right occipital lobe (middle occipital gyrus, right insula, right parahippocampal gyrus, and left cingulate gyrus. The voxel sizes of atrophic gray matter positively correlated with fractional anisotropy values in white matter association fibers in the patient group. These findings suggest that white matter fiber bundles are extensively injured in multiple sclerosis patients. The main areas of gray matter atrophy in multiple sclerosis are the frontal lobe, parietal lobe, caudate nucleus, parahippocampal gyrus, and cingulate gyrus. Gray matter atrophy is strongly associated with white matter injury in multiple sclerosis patients, particularly with injury to association fibers.

  1. The field size matters: low dose external beam radiotherapy for thumb carpometacarpal osteoarthritis : Importance of field size.

    Science.gov (United States)

    Kaltenborn, Alexander; Bulling, Elke; Nitsche, Mirko; Carl, Ulrich Martin; Hermann, Robert Michael

    2016-08-01

    The purpose of this work was to evaluate the efficacy of low-dose radiotherapy (RT) for thumb carpometacarpal osteoarthritis (rhizarthrosis). The responses of 84 patients (n = 101 joints) were analyzed 3 months after therapy (n = 65) and at 12 months (n = 27). Patients were treated with 6 fractions of 1 Gy, two times a week, with a linear accelerator. At the end of therapy, about 70 % of patients reported a response (partial remission or complete remission), 3 months later about 60 %, and 1 year after treatment 70 %. In univariate regression analysis, higher patient age and field size greater than 6 × 4 cm were associated with response to treatment, while initial increase of pain under treatment was predictive for treatment failure. Duration of RT series (more than 18 days), gender, time of symptoms before RT, stress pain or rest pain, or prior ortheses use, injections, or surgery of the joint were not associated with treatment efficacy. In multivariate regression analysis, only field size and initial pain increase were highly correlated with treatment outcome. In conclusion, RT represents a useful treatment option for patients suffering from carpometacarpal osteoarthritis. In contrast to other benign indications, a larger field size (>6 × 4 cm) seems to be more effective than smaller fields and should be evaluated in further prospective studies.

  2. Size does matter: an integrative in vivo-in silico approach for the treatment of critical size bone defects.

    Directory of Open Access Journals (Sweden)

    Aurélie Carlier

    2014-11-01

    Full Text Available Although bone has a unique restorative capacity, i.e., it has the potential to heal scarlessly, the conditions for spontaneous bone healing are not always present, leading to a delayed union or a non-union. In this work, we use an integrative in vivo-in silico approach to investigate the occurrence of non-unions, as well as to design possible treatment strategies thereof. The gap size of the domain geometry of a previously published mathematical model was enlarged in order to study the complex interplay of blood vessel formation, oxygen supply, growth factors and cell proliferation on the final healing outcome in large bone defects. The multiscale oxygen model was not only able to capture the essential aspects of in vivo non-unions, it also assisted in understanding the underlying mechanisms of action, i.e., the delayed vascularization of the central callus region resulted in harsh hypoxic conditions, cell death and finally disrupted bone healing. Inspired by the importance of a timely vascularization, as well as by the limited biological potential of the fracture hematoma, the influence of the host environment on the bone healing process in critical size defects was explored further. Moreover, dependent on the host environment, several treatment strategies were designed and tested for effectiveness. A qualitative correspondence between the predicted outcomes of certain treatment strategies and experimental observations was obtained, clearly illustrating the model's potential. In conclusion, the results of this study demonstrate that due to the complex non-linear dynamics of blood vessel formation, oxygen supply, growth factor production and cell proliferation and the interactions thereof with the host environment, an integrative in silico-in vivo approach is a crucial tool to further unravel the occurrence and treatments of challenging critical sized bone defects.

  3. Size partitioning and mixing behavior of trace metals and dissolved organic matter in a South China estuary.

    Science.gov (United States)

    Wang, Wenhao; Chen, Min; Guo, Laodong; Wang, Wen-Xiong

    2017-12-15

    The Jiulong River estuary, located in the southeastern China, suffered from metal pollution due to industrial effluent releases. Mixing of effluent and estuarine water may have significantly affected the size distribution of trace metals and their environmental fate. In the present study, colloidal size distribution of organic matter and selected metals were quantified using asymmetric flow field-flow fractionation (AF4) and ICP-MS. We demonstrated a dominance of dissolved metals in the 1-10kDa fraction, and metals such as Cu, Zn, Ni, Co, Pb, Cd and Mn were mostly regulated by terrestrial fulvic acid. The larger inorganic colloids played a limited role, although Fe reduction was likely to affect the size partitioning of colloidal Mn. The holding pond represented a source of trace metals and chromophoric and humic-like dissolved organic matter to the estuary. Scavenging or removal behavior became evident following the intermittent mixing, and the small sized colloidal organic complexes were responsible for binding and stabilizing trace metals. Variations in particle size distributions indicated different sources, fates and geochemical controls of the metals. Our results highlighted the impacts of both natural and anthropogenic processes on the transformation of trace metals among phases in this dynamic estuary system. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Quality control considerations for size exclusion chromatography with online ICP-MS: a powerful tool for evaluating the size dependence of metal-organic matter complexation

    Science.gov (United States)

    McKenzie, Erica R.; Young, Thomas M.

    2013-01-01

    Size exclusion chromatography (SEC), which separates molecules based on molecular volume, can be coupled with online inductively coupled plasma mass spectrometry (ICP-MS) to explore size-dependent metal-natural organic matter (NOM) complexation. To make effective use of this analytical dual detector system, the operator should be mindful of quality control measures. Al, Cr, Fe, Se, and Sn all exhibited columnless attenuation, which indicated unintended interactions with system components. Based on signal-to-noise ratio and peak reproducibility between duplicate analyses of environmental samples, consistent peak time and height were observed for Mg, Cl, Mn, Cu, Br, and Pb. Al, V, Fe, Co, Ni, Zn, Se, Cd, Sn, and Sb were less consistent overall, but produced consistent measurements in select samples. Ultrafiltering and centrifuging produced similar peak distributions, but glass fiber filtration produced more high molecular weight peaks. Storage in glass also produced more high molecular weight peaks than did plastic bottles. PMID:23416600

  5. Size matter! A choice architectural field experiment in reducing food waste

    OpenAIRE

    Guldborg Hansen, Pelle; Maaløe Jespersen, Andreas; Skov, Laurits Rohden

    2015-01-01

    Objectives We examined how a reduction in plate size would affect the amount of food waste from leftovers in a field experiment at a standing lunch for 220 CEOs. Methods A standing lunch for 220 CEOs in the Danish Opera House was arranged to feature two identical buffets with plates of two different sizes. One buffet featured standard sized plates that served as control (standard size as provided by the caterer, 27cm). A second buffet featured smaller sized plates (24cm) that served as the in...

  6. 应用基于体素的MR形态测量学分析抽动秽语综合征患儿脑灰质体积变化%Volume changes of whole brain gray matter in pediatric patients with Tourette syndrome: evidence from voxel-based morphometry

    Institute of Scientific and Technical Information of China (English)

    刘玥; 单保慈; 彭芸; 高培毅; 聂彬彬; 吕传凯; 张礼萍; 季之颖; 尹光恒; 于彤

    2012-01-01

    目的 应用优化的基于体素的形态测量学(VBM)技术,分析抽动秽语综合征(TS)患儿全脑灰质异常情况.方法 选取31例TS患儿(TS组)和与之年龄、性别匹配的50名正常儿童(正常对照组)进行3DT1WI.利用基于统计参数图(SPM)2软件的VBM 2工具箱对扫描获得的图像进行预处理,对TS患儿和正常儿童的全脑灰质体积采用t检验进行比较.将灰质体积差异区域的改变值提取出来,与临床耶鲁综合抽动严重程度评分量表(YGTSS)评分、病程进行多元线性分析.结果 应用VBM方法,发现TS组的左顶上小叶、右小脑半球、左海马旁回灰质体积较对照组增大,增加体积分别为4059、2126、84 mm3,其差异有统计学意义(t值分别为3.93、3.71、3.58,P值均<0.05).延髓和左桥脑体积较对照组减小,减小体积分别为213、117 mm3(t值分别为3.53、3.48,P值均<0.05).体积差异区域的体积改变值与临床YGTSS评分无相关性(P>0.05),左海马旁回灰质体积与患儿病程呈负相关(Beta=-0.391,P=0.039).结论 VBM能够显示常规MRI表现正常的TS患儿的灰质异常.颡顶叶和小脑体积增加可能是TS患儿的适应性反应,左海马旁回灰质体积可能是评价TS患者预后的一项客观指标.%Objectives To identify the related abnormalities of gray matter in pediatric patients with Tourette syndrome (TS) by using the optimized voxel-based morphometry (VBM).Methods Three dimensional T1WI was acquired in 31 TS children (28 boys,3 girts,mean age 8 years,range 4-15 years) and 50 age- and sex-matched controls on a 1.5 Tesla Philips scanner. Images were pre-processed and analyzed using a version of VBM 2 in SPM 2.The whole brain gray matter volume was compared between the study and control group by using t-test.Multivariate linear regression analysis was used for analyzing the correlation between the change of grey matter volume within each brain region (mm3 ) and YGTSS score and course of disease of

  7. 运用基于体素的脑形态测量学法检测缺陷型及非缺陷型精神分裂症患者脑灰质结构异常%Gray matter volume differences in deficit and nondeficit schizophrenia:a voxel-based morphometric study

    Institute of Scientific and Technical Information of China (English)

    王晓晟; 王湘; 颜莉蓉; 谭长连; 司徒卫军; 李亚军; 姚树桥

    2010-01-01

    Objective To examine the differences in the structure of brain white matter among deficit schizophrenia, nondeficit schizophrenia and healthy controls by using voxel-based morphometry (VBM). Methods Ten deficit schizophrenic patients, eleven nondeficit patients and fifteen healthy comparison subjects participated in the study. All the subjects were scanned by GE Twin Speed 1.5T MRI system. Whole brain, voxel-wise analyses of regional white matter volume were conducted by the VBM toolbox on the Matlab7.6 and SPM5. t -test was then used for the comparison between groups. Results Compared to the healthy controls, nondeficit schizophrenic patients significantly decreased the density of gray matter in the frontal, parietal, temporal, occipital lobe and basal ganglia , while the deficit patients showed the characteristically broad and significant decreasion in the frontal lobe, including left medial frontal gyrus, bilateral inferior frontal gyrus, left middle frontal gyrus, and left orbital gyrus (Cluster ≥ 30 mm3, P<0.01). Moreover, deficit patients showed the decreasion in the temporal cortex and the limbic lobe (right insula). Relative to the nondeficit schizophrenic patients, deficit patients had significant regional gray matter decreases in the left medial frontal gyrus, bilateral inferior frontal gyrus, right precentral gyrus, and right superior temporal gyrus (Cluster ≥ 30 mm3, P<0.01). Conclusion Structural heterogeneity in schizophrenia may relate to specific patterns of gray matter density reductions in deficit and nondeficit patient. However the two subtype of schizophremia patients share a common prefrontal-temperal pattern of structural brain alterations.%目的 应用基于体素的脑形态测量学(Voxel-based Morphometric,VBM)法,比较缺陷型与非缺陷型精神分裂症患者大脑灰质结构损害的差异.方法 采用GE Signa TwinSpeed 1.5T超导型MRI成像系统,对缺陷型精神分裂症(N=10)、非缺陷型精神分裂症(n=11)

  8. Estimating the size and abundance of dark matter subhaloes with gravitational millilensing

    Science.gov (United States)

    Vives-Arias, H.; Jiménez-Vicente, J.; Muñoz, J. A.; Mediavilla, E.

    2017-03-01

    We use 8 gravitational lens systems with quadruply imaged quasars and their observed flux ratio anomalies obtained using data in mid-infrared, radio or spectral narrow lines as a baseline, to estimate the amount of substructure in the dark matter halo of lens galaxies. We assume that the smooth gravitational potential of the galaxies is well modeled by a Singular Isothermal Ellipsoid (SIE) plus external shear (γ) and an additional Singular Isothermal Sphere (SIS) in some cases, and that the cause of the flux ratio anomalies is dark matter subhalos described by pseudo-Jaffe density profiles. Our Bayesian estimate for the Einstein radius of the subhalos is b = 0.0003^{+0.0005}_{-0.0002} arcsec, and their abundance (as a fraction of the total surface density of the lens galaxy at the image positions) is α =Ê0.075^{+0.030}_{-0.021}.

  9. Voxel-Based LIDAR Analysis and Applications

    Science.gov (United States)

    Hagstrom, Shea T.

    One of the greatest recent changes in the field of remote sensing is the addition of high-quality Light Detection and Ranging (LIDAR) instruments. In particular, the past few decades have been greatly beneficial to these systems because of increases in data collection speed and accuracy, as well as a reduction in the costs of components. These improvements allow modern airborne instruments to resolve sub-meter details, making them ideal for a wide variety of applications. Because LIDAR uses active illumination to capture 3D information, its output is fundamentally different from other modalities. Despite this difference, LIDAR datasets are often processed using methods appropriate for 2D images and that do not take advantage of its primary virtue of 3-dimensional data. It is this problem we explore by using volumetric voxel modeling. Voxel-based analysis has been used in many applications, especially medical imaging, but rarely in traditional remote sensing. In part this is because the memory requirements are substantial when handling large areas, but with modern computing and storage this is no longer a significant impediment. Our reason for using voxels to model scenes from LIDAR data is that there are several advantages over standard triangle-based models, including better handling of overlapping surfaces and complex shapes. We show how incorporating system position information from early in the LIDAR point cloud generation process allows radiometrically-correct transmission and other novel voxel properties to be recovered. This voxelization technique is validated on simulated data using the Digital Imaging and Remote Sensing Image Generation (DIRSIG) software, a first-principles based ray-tracer developed at the Rochester Institute of Technology. Voxel-based modeling of LIDAR can be useful on its own, but we believe its primary advantage is when applied to problems where simpler surface-based 3D models conflict with the requirement of realistic geometry. To

  10. Gait analysis and validation using voxel data.

    Science.gov (United States)

    Wang, Fang; Stone, Erik; Dai, Wenqing; Skubic, Marjorie; Keller, James

    2009-01-01

    In this paper, we present a method for extracting gait parameters including walking speed, step time and step length from a three-dimensional voxel reconstruction, which is built from two calibrated camera views. These parameters are validated with a GAITRite Electronic mat and a Vicon motion capture system. Experiments were conducted in which subjects walked across the GAITRite mat at various speeds while the Vicon cameras recorded the motion of reflective markers attached to subjects' shoes, and our two calibrated cameras captured the images. Excellent agreements were found for walking speed. Step time and step length were also found to have good agreement given the limitation of frame rate and voxel resolution.

  11. On the Impact of Layout Quality to Understanding UML Diagrams: Size Matters

    DEFF Research Database (Denmark)

    Störrle, Harald

    2014-01-01

    studying different factors like diagram type and expertise level, it became apparent that diagram size plays an important role, too. Since we lack an adequate understanding of this notion, in this paper, we define diagram size metrics and study their impact to modeler performance. We find...

  12. Does print size matter for reading? A review of findings from vision science and typography.

    Science.gov (United States)

    Legge, Gordon E; Bigelow, Charles A

    2011-08-09

    The size and shape of printed symbols determine the legibility of text. In this paper, we focus on print size because of its crucial role in understanding reading performance and its significance in the history and contemporary practice of typography. We present evidence supporting the hypothesis that the distribution of print sizes in historical and contemporary publications falls within the psychophysically defined range of fluent print size--the range over which text can be read at maximum speed. The fluent range extends over a factor of 10 in angular print size (x-height) from approximately 0.2° to 2°. Assuming a standard reading distance of 40 cm (16 inches), the corresponding physical x-heights are 1.4 mm (4 points) and 14 mm (40 points). We provide new data on the distributions of print sizes in published books and newspapers and in typefounders' specimens, and consider factors influencing these distributions. We discuss theoretical concepts from vision science concerning visual size coding that help inform our understanding of historical and modern typographical practices. While economic, social, technological, and artistic factors influence type design and selection, we conclude that properties of human visual processing play a dominant role in constraining the distribution of print sizes in common use.

  13. Particulate matter and atherosclerosis: role of particle size, composition and oxidative stress

    OpenAIRE

    2009-01-01

    Abstract Air Pollution has been associated with significant adverse health effects leading to increased morbidity and mortality. Cumulative epidemiological and experimental data have shown that exposure to air pollutants lead to increased cardiovascular ischemic events and enhanced atherosclerosis. It appears that these associations are much stronger with the air particulate matter (PM) component and that in urban areas, the smaller particles could be more pathogenic, as a result of their gre...

  14. Educational Vouchers When There Are Peer Group Effects--Size Matters

    OpenAIRE

    Caucutt, Elizabeth M.

    2002-01-01

    In this article, I study the effects various educational voucher policies have on the sorting of children across schools and the per-student expenditure levels at these schools, when a child's peer group matters and students differ over income and ability. I find that, depending on the magnitude of the voucher, switching from a public system to a voucher system could entail either welfare gains or losses. All voucher policies under consideration lead to greater inequality than the public syst...

  15. Plastic marine debris on the Portuguese coastline: a matter of size?

    Science.gov (United States)

    Martins, J; Sobral, P

    2011-12-01

    Plastic debris is a worldwide threat to marine environments and Portugal is not immune to it. Though never quantified, items of all sizes can be found in the Portuguese coastline; therefore the objective of this work is the identification of main size classes in stranded plastic debris. Beaches sediment was sampled and in the laboratory plastic items were sorted in 11 classes from 10mm, counted and weighted. Plastic size ranged from 50 μm to 20 cm and microplastics (plastic fits in the smaller size classes, due to expected high residence time in the sea enhancing degradation processes, which increase surface exposure and potentially persistent organic pollutants (POP) adsorption. These results point out the important contribution of microplastics to marine debris pollution, its risks, and the need to set a higher focus on this size class.

  16. Molecular size-dependent abundance and composition of dissolved organic matter in river, lake and sea waters.

    Science.gov (United States)

    Xu, Huacheng; Guo, Laodong

    2017-06-15

    Dissolved organic matter (DOM) is ubiquitous in natural waters. The ecological role and environmental fate of DOM are highly related to the chemical composition and size distribution. To evaluate size-dependent DOM quantity and quality, water samples were collected from river, lake, and coastal marine environments and size fractionated through a series of micro- and ultra-filtrations with different membranes having different pore-sizes/cutoffs, including 0.7, 0.4, and 0.2 μm and 100, 10, 3, and 1 kDa. Abundance of dissolved organic carbon, total carbohydrates, chromophoric and fluorescent components in the filtrates decreased consistently with decreasing filter/membrane cutoffs, but with a rapid decline when the filter cutoff reached 3 kDa, showing an evident size-dependent DOM abundance and composition. About 70% of carbohydrates and 90% of humic- and protein-like components were measured in the properties of DOM, such as specific ultraviolet absorbance, spectral slope, and biological and humification indices also varied significantly with membrane cutoffs. In addition, different ultrafiltration membranes with the same manufacture-rated cutoff also gave rise to different DOM retention efficiencies and thus different colloidal abundances and size spectra. Thus, the size-dependent DOM properties were related to both sample types and membranes used. Our results here provide not only baseline data for filter pore-size selection when exploring DOM ecological and environmental roles, but also new insights into better understanding the physical definition of DOM and its size continuum in quantity and quality in aquatic environments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. 基于体素的孤独症谱系障碍儿童脑灰质体积研究%A typical gray matter volume in children with autism spectrum disorder: a voxel-based morphometric study

    Institute of Scientific and Technical Information of China (English)

    牛丽薇; 王佳; 陈恒; 陈磊; 吴琼; 张碧珊; 孙彩虹; 夏薇; 陈华富

    2016-01-01

    目的 比较孤独症谱系障碍(ASD)儿童和正常对照儿童的大脑灰质体积,探索ASD大脑结构异常的神经影像学证据.方法 采集21例ASD儿童及9名正常儿童的全脑T1结构MRI图像,采用基于体素的形态学测量(VBM)方法计算两组被试大脑各区域的灰质体积,并采用双样本t检验结合Alphasim多重检验矫正寻找差异脑区,采用多元回归分析与相关分析探究ASD组异常脑区的灰质体积与临床表型和年龄的关系.结果 与对照组相比,ASD组中灰质体积增大的区域位于楔前叶、距状皮层、舌回和左侧扣带回后部以及左侧缘上回、左侧颞上回、左侧顶下小叶、左侧中央后回、左侧罗兰迪克岛盖和左侧颞中回(校正后P值均<0.05).异常的左侧缘上回和左侧顶下小叶灰质体积与孤独症诊断访谈量表社会互动障碍(r=-0.64,P=0.002)和孤独症诊断观察量表相互性社会互动(r=-0.58,P=0.006)得分均呈负相关.ASD组中存在差异的脑区灰质体积随着年龄增大呈减小的趋势(r=-0.52,P=0.017),而对照组中未见该趋势(r=-0.15,P=0.69).结论 ASD儿童灰质体积改变见于多个脑区,ASD儿童大脑结构存在明显异常.%Objective To compare the gray matter volume (GMV) of ASD children with healthy control and to explore the neuroimaging evidence associated with ASD brain structure.Methods Whole-brain T1 MRI scans were collected both from 21 ASD children and 9 normal children,VBM analysis was performed to calculate the GMV of each brain regions.A two-sample t test combining Alphasim multiple test correction was utilized to explore the regions with atypical GMV,then a multi-regression analysis was performed to determine the relationship between the GMV of atypical regions and symptoms of ASD,and the development course of two groups.Results Compared with HC group,ASD exhibited increased GMV in precuneus,calcarine,lingual gyrus,left posterior cingulated,left supramarginal gyrus

  18. Voxel2MCNP: software for handling voxel models for Monte Carlo radiation transport calculations.

    Science.gov (United States)

    Hegenbart, Lars; Pölz, Stefan; Benzler, Andreas; Urban, Manfred

    2012-02-01

    Voxel2MCNP is a program that sets up radiation protection scenarios with voxel models and generates corresponding input files for the Monte Carlo code MCNPX. Its technology is based on object-oriented programming, and the development is platform-independent. It has a user-friendly graphical interface including a two- and three-dimensional viewer. A row of equipment models is implemented in the program. Various voxel model file formats are supported. Applications include calculation of counting efficiency of in vivo measurement scenarios and calculation of dose coefficients for internal and external radiation scenarios. Moreover, anthropometric parameters of voxel models, for instance chest wall thickness, can be determined. Voxel2MCNP offers several methods for voxel model manipulations including image registration techniques. The authors demonstrate the validity of the program results and provide references for previous successful implementations. The authors illustrate the reliability of calculated dose conversion factors and specific absorbed fractions. Voxel2MCNP is used on a regular basis to generate virtual radiation protection scenarios at Karlsruhe Institute of Technology while further improvements and developments are ongoing.

  19. Voxel-based morphometry in autopsy proven PSP and CBD.

    Science.gov (United States)

    Josephs, Keith A; Whitwell, Jennifer L; Dickson, Dennis W; Boeve, Bradley F; Knopman, David S; Petersen, Ronald C; Parisi, Joseph E; Jack, Clifford R

    2008-02-01

    The aim of this study was to compare the patterns of grey and white matter atrophy on MRI in autopsy confirmed progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD), and to determine whether the patterns vary depending on the clinical syndrome. Voxel-based morphometry was used to compare patterns of atrophy in 13 PSP and 11 CBD subjects and 24 controls. PSP and CBD subjects were also subdivided into those with a dominant dementia or extrapyramidal syndrome. PSP subjects showed brainstem atrophy with involvement of the cortex and underlying white matter. Frontoparietal grey and subcortical grey matter atrophy occurred in CBD. When subdivided, PSP subjects with an extrapyramidal syndrome had more brainstem atrophy and less cortical atrophy than CBD subjects with an extrapyramidal syndrome. PSP subjects with a dementia syndrome had more subcortical white matter atrophy than CBD subjects with a dementia syndrome. These results show regional differences between PSP and CBD that are useful in predicting the underlying pathology, and help to shed light on the in vivo distribution of regional atrophy in PSP and CBD.

  20. Modelling of airborne particulate matter concentration in underground stations using a two size-class conservation model.

    Science.gov (United States)

    Walther, E; Bogdan, M; Cohen, R

    2017-12-31

    This study presents an attempt of predictive modelling of airborne particulate matter in underground railway stations. The aerosol is represented by a set of simple, ordinary differential equations that describe apparent emission of two particles size-classes in relation with train traffic, ventilation and deposition. The parameters of the equations are identified numerically by a genetic algorithm and comply with their respective expected order of magnitude. A quantitative comparison of numerical results with experimental data from Paris underground station exhibits a good accordance. A qualitative comparison with results from the literature also supports the model. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. New vortex-matter size effect observed in Bi(2)Sr(2)CaCu(2)O(8 + delta).

    Science.gov (United States)

    Wang, Y M; Fuhrer, M S; Zettl, A; Ooi, S; Tamegai, T

    2001-04-16

    The vortex-matter 3D to 2D phase transition is studied in micron-sized Bi(2)Sr(2)CaCu(2)O(8 + delta) single crystals using local Hall magnetization measurements. At a given temperature, the second magnetization peak, the signature of a possible 3D--2D vortex phase transition, disappears for samples smaller than a critical length. We suggest that this critical length should be equated with the 2D vortex lattice ab-plane correlation length R(2D)(c). The magnitude and temperature dependence of R(2D)(c) agree well with Larkin-Ovchinnikov collective pinning theory.

  2. Soil structure and soil organic matter: I. Distribution of aggregate size classes and aggregate associated carbon

    OpenAIRE

    J. Six; K. Paustian; Elliott, E.T.; C. Combrink

    2000-01-01

    Metadata only record This study compares aggregate size and carbon in three different soils, each with three tillage treatments (native vegetation (NV), no-tillage (NT), and conventional tillage (CT)).

  3. Economy, Speed and Size Matter: Evolutionary Forces Driving Nuclear Genome Miniaturization and Expansion

    OpenAIRE

    CAVALIER-SMITH, THOMAS

    2005-01-01

    • Background Nuclear genome size varies 300 000-fold, whereas transcriptome size varies merely 17-fold. In the largest genomes nearly all DNA is non-genic secondary DNA, mostly intergenic but also within introns. There is now compelling evidence that secondary DNA is functional, i.e. positively selected by organismal selection, not the purely neutral or ‘selfish’ outcome of mutation pressure. The skeletal DNA theory argued that nuclear volumes are genetically determined primarily by nuclear D...

  4. The Relationship Between Banking Market Competition and Risk-taking: Do Size and Capitalization Matter?

    OpenAIRE

    Benjamin M. Tabak; Dimas M. Fazio; Cajueiro, Daniel O.

    2011-01-01

    This paper aims to study the effect of banking competition on Latin American banks' risk-taking and whether capitalization and size changes this relationship. We conclude that: (1) competition affects risk in a non-linear manner: high/low (average) competition are related to more (less) stability; (2) bank's size explains the advantage from competition, while capitalization is only positive for larger banks in this case; (3) capital ratio explains the advantage from lower competition. These r...

  5. Characterization of size-specific particulate matter emission rates for a simulated medical laser procedure--a pilot study.

    Science.gov (United States)

    Lopez, Ramon; Lacey, Steven E; Lippert, Julia F; Liu, Li C; Esmen, Nurtan A; Conroy, Lorraine M

    2015-05-01

    Prior investigation on medical laser interaction with tissue has suggested device operational parameter settings influence laser generated air contaminant emission, but this has not been systematically explored. A laboratory-based simulated medical laser procedure was designed and pilot tested to determine the effect of laser operational parameters on the size-specific mass emission rate of laser generated particulate matter. Porcine tissue was lased in an emission chamber using two medical laser systems (CO2, λ = 10,600 nm; Ho:YAG, λ = 2100 nm) in a fractional factorial study design by varying three operational parameters (beam diameter, pulse repetition frequency, and power) between two levels (high and low) and the resultant plume was measured using two real-time size-selective particle counters. Particle count concentrations were converted to mass emission rates before an analysis of variance was used to determine the influence of operational parameter settings on size-specific mass emission rate. Particle shape and diameter were described for a limited number of samples by collecting particles on polycarbonate filters, and photographed using a scanning electron microscope (SEM) to examine method of particle formation. An increase in power and decrease in beam diameter led to an increase in mass emission for the Ho:YAG laser at all size ranges. For the CO2 laser, emission rates were dependent on particle size and were not statistically significant for particle ranges between 5 and 10 µm. When any parameter level was increased, emission rate of the smallest particle size range also increased. Beam diameter was the most influential variable for both lasers, and the operational parameters tested explained the most variability at the smallest particle size range. Particle shape was variable and some particles observed by SEM were likely created from mechanical methods. This study provides a foundation for future investigations to better estimate size

  6. Genetics of recent habitat contraction and reduction in population size: does isolation by distance matter?

    Science.gov (United States)

    Leblois, Raphael; Estoup, Arnaud; Streiff, Rejane

    2006-10-01

    Fragmentation and loss of natural habitats are recognized as major threats to contemporary flora and fauna. Detecting past or current reductions in population size is therefore a major aim in conservation genetics. Statistical methods developed to this purpose have tended to ignore the effects of spatial population structure. However in many species, individual dispersal is restricted in space and fine-scale spatial structure such as isolation by distance (IBD) is commonly observed in continuous populations. Using a simulation-based approach, we investigated how comparative and single-point methods, traditionally used in a Wright-Fisher (WF) population context for detecting population size reduction, behave for IBD populations. We found that a complex 'quartet' of factors was acting that includes restricted dispersal, population size (i.e. habitat size), demographic history, and sampling scale. After habitat reduction, IBD populations were characterized by a stronger inertia in the loss of genetic diversity than WF populations. This inertia increases with the strength of IBD, and decreases when the sampling scale increases. Depending on the method used to detect a population size reduction, a local sampling can be more informative than a sample scaled to habitat size or vice versa. However, IBD structure led in numerous cases to incorrect inferences on population demographic history. The reanalysis of a real microsatellite data set of skink populations from fragmented and intact rainforest habitats confirmed most of our simulation results.

  7. Characterization of particulate matter size distributions and indoor concentrations from kerosene and diesel lamps.

    Science.gov (United States)

    Apple, J; Vicente, R; Yarberry, A; Lohse, N; Mills, E; Jacobson, A; Poppendieck, D

    2010-10-01

    Over one-quarter of the world's population relies on fuel-based lighting. Kerosene lamps are often located in close proximity to users, potentially increasing the risk for respiratory illnesses and lung cancer. Particulate matter concentrations resulting from cook stoves have been extensively studied in the literature. However, characterization of particulate concentrations from fuel-based lighting has received minimal attention. This research demonstrates that vendors who use a single simple wick lamp in high-air-exchange market kiosks will likely be exposed to PM(2.5) concentrations that are an order of magnitude greater than ambient health guidelines. Using a hurricane lamp will reduce exposure to PM(2.5) and PM(10) concentrations by an order of magnitude compared to using a simple wick lamp. Vendors using a single hurricane or pressure lamp may not exceed health standards or guidelines for PM(2.5) and PM(10), but will be exposed to elevated 0.02-0.3 μm particle concentrations. Vendors who change from fuel-based lighting to electric lighting technology for enhanced illumination will likely gain the ancillary health benefit of reduced particulate matter exposure. Vendors exposed only to ambient and fuel-based lighting particulate matter would see over an 80% reduction in inhaled PM(2.5) mass if they switched from a simple wick lamp to an electric lighting technology. Changing lighting technologies to achieve increased efficiency and energy service levels can provide ancillary health benefits. The cheapest, crudest kerosene lamps emit the largest amounts of PM(2.5). Improving affordability and access to better lighting options (hurricane or pressure lamps and lighting using grid or off-grid electricity) can deliver health benefits for a large fraction of the world's population, while reducing the economic and environmental burden of the current fuel-based lighting technologies.

  8. The Inner Structure of Dwarf-sized Halos in Warm and Cold Dark Matter Cosmologies

    Science.gov (United States)

    González-Samaniego, A.; Avila-Reese, V.; Colín, P.

    2016-03-01

    By means of N-body + hydrodynamic zoom-in simulations we study the evolution of the inner dark matter and stellar mass distributions of central dwarf galaxies formed in halos of virial masses Mv = (2-3) × 1010 h-1 M⊙ at z = 0, both in a warm dark matter (WDM) and cold dark matter (CDM) cosmology. The half-mode mass in the WDM power spectrum of our simulations is Mf = 2 × 1010 h-1 M⊙. In the dark matter (DM) only simulations halo density profiles are well described by the Navarro-Frenk-White parametric fit in both cosmologies, though the WDM halos have concentrations lower by factors of 1.5-2.0 than their CDM counterparts. In the hydrodynamic simulations, the effects of baryons significantly flatten the inner density, velocity dispersion, and pseudo phase space density profiles of the WDM halos but not of the CDM ones. The density slope, measured at ≈0.02Rv, α0.02, becomes shallow in periods of 2-5 Gyr in the WDM runs. We explore whether this flattening process correlates with the global star formation (SF), Ms/Mv ratio, gas outflow, and internal specific angular momentum histories. We do not find any clear trends, but when α0.02 is shallower than -0.5, Ms/Mv is always between 0.25% and 1%. We conclude that the main reason for the formation of the shallow core is the presence of strong gas mass fluctuations inside the inner halo, which are a consequence of the feedback driven by a very bursty and sustained SF history in shallow gravitational potentials. Our WDM halos, which assemble late and are less concentrated than the CDM ones, obey these conditions. There are also (rare) CDM systems with extended mass assembly histories that obey these conditions and form shallow cores. The dynamical heating and expansion processes behind the DM core flattening apply also to the stars in such a way that the stellar age and metallicity gradients of the dwarfs are softened, their stellar half-mass radii strongly grow with time, and their central surface densities

  9. THE INNER STRUCTURE OF DWARF-SIZED HALOS IN WARM AND COLD DARK MATTER COSMOLOGIES

    Energy Technology Data Exchange (ETDEWEB)

    González-Samaniego, A.; Avila-Reese, V. [Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 70-264, 04510, México, D.F., México (Mexico); Colín, P. [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, A.P. 72-3 (Xangari), Morelia, Michoacán 58089, México (Mexico)

    2016-03-10

    By means of N-body + hydrodynamic zoom-in simulations we study the evolution of the inner dark matter and stellar mass distributions of central dwarf galaxies formed in halos of virial masses M{sub v} = (2–3) × 10{sup 10} h{sup −1} M{sub ⊙} at z = 0, both in a warm dark matter (WDM) and cold dark matter (CDM) cosmology. The half-mode mass in the WDM power spectrum of our simulations is M{sub f} = 2 × 10{sup 10} h{sup −1} M{sub ⊙}. In the dark matter (DM) only simulations halo density profiles are well described by the Navarro–Frenk–White parametric fit in both cosmologies, though the WDM halos have concentrations lower by factors of 1.5–2.0 than their CDM counterparts. In the hydrodynamic simulations, the effects of baryons significantly flatten the inner density, velocity dispersion, and pseudo phase space density profiles of the WDM halos but not of the CDM ones. The density slope, measured at ≈0.02R{sub v}, α{sub 0.02}, becomes shallow in periods of 2–5 Gyr in the WDM runs. We explore whether this flattening process correlates with the global star formation (SF), M{sub s}/M{sub v} ratio, gas outflow, and internal specific angular momentum histories. We do not find any clear trends, but when α{sub 0.02} is shallower than −0.5, M{sub s}/M{sub v} is always between 0.25% and 1%. We conclude that the main reason for the formation of the shallow core is the presence of strong gas mass fluctuations inside the inner halo, which are a consequence of the feedback driven by a very bursty and sustained SF history in shallow gravitational potentials. Our WDM halos, which assemble late and are less concentrated than the CDM ones, obey these conditions. There are also (rare) CDM systems with extended mass assembly histories that obey these conditions and form shallow cores. The dynamical heating and expansion processes behind the DM core flattening apply also to the stars in such a way that the stellar age and metallicity gradients of the

  10. A Census of Baryons and Dark Matter in an Isolated, Milky Way-sized Elliptical Galaxy

    CERN Document Server

    Humphrey, Philip J; Canizares, Claude R; Fabian, Andrew C; Miller, Jon M

    2010-01-01

    We present a study of the dark and luminous matter in the isolated elliptical galaxy NGC720, based on deep X-ray data taken with Chandra and Suzaku. The gas is reliably measured to ~R2500, allowing us to place good constraints on the enclosed mass and baryon fraction (fb) within this radius (M2500=1.6e12+/-0.2e12 Msun, fb(2500)=0.10+/-0.01; systematic errors are <~20%). The data indicate that the hot gas is close to hydrostatic, which is supported by good agreement with a kinematical analysis of the dwarf satellite galaxies. We confirm a dark matter (DM) halo at ~20-sigma. Assuming an NFW DM profile, our physical model for the gas distribution enables us to obtain meaningful constraints at scales larger than R2500, revealing that most of the baryons are in the hot gas. We find that fb within Rvir is consistent with the Cosmological value, confirming theoretical predictions that a ~Milky Way-mass (Mvir=3.1e12+/-0.4e12 Msun) galaxy can sustain a massive, quasi-hydrostatic gas halo. While fb is higher than th...

  11. The inner structure of dwarf sized halos in Warm and Cold Dark Matter cosmologies

    CERN Document Server

    Gonzalez-Samaniego, Alejandro; Colin, Pedro

    2015-01-01

    By means of N-body+Hydrodynamics zoom-in simulations we study the evolution of the inner dark matter and stellar mass distributions of central dwarf galaxies formed in halos of virial masses mh=2-3x10^10 Msun at z=0, both in a WDM and CDM cosmology. The half-mode mass in the WDM power spectrum of our simulations is Mv= 2x 10^10 Msun. In the dark matter only simulations halo density profiles are well described by the NFW parametric fit in both cosmologies, though the WDM halos have concentrations lower by factors 1.5--2.0 than their CDM counterparts. In the hydrodynamical simulations, the effects of baryons significantly flatten the inner density, velocity dispersion, and pseudo phase-space density profiles of the WDM halos but not of the CDM ones. The density slope measured at ~ 0.02xRv, alpha, becomes shallow in periods of 2 to 5 Gyr in the WDM runs. We explore whether this flattening process correlates with the global SF, Ms/Mv ratio, gas outflow, and internal specific angular momentum histories. We do not ...

  12. Water-soluble organic carbon in urban aerosol: concentrations, size distributions and contribution to particulate matter

    Energy Technology Data Exchange (ETDEWEB)

    Timonen, H. J.; Saarikoski, S. K.; Aurela, M. A.; Saarnio, K. M.; Hillamo, R. E. (Finnish Meteorological Inst., Helsinki (Finland))

    2008-07-01

    The aim of this study was to characterize the concentrations and particle mass size distributions of water-soluble organic carbon (WSOC) in urban aerosols. The sample collection was carried out in spring 2006 at the SMEAR III station in Helsinki, Finland, by using a size-segregating method (MOUDI) and by collecting sub-micrometer fraction of aerosols on the filter. During the three-month measurement period, a major 12-day biomass burning pollution episode was observed. Concentrations of WSOC, organic carbon, monosaccharide anhydrides, inorganic ions and some organic acids (oxalic, succinic and malonic acid) were analyzed from the PM{sub 1} samples. The measured OC and WSOC concentrations varied in ranges 0.67-15.7 mug m-3 and 0.26-10.7 mug m3, respectively. The WSOC/OC concentration ratio was between 0.30 and 0.89 with an average of 0.54. Size distributions of WSOC, inorganic ions and total mass were determined from the MOUDI samples. WSOC had bimodal size distributions with a clear accumulation mode below 1 mum of particle aerodynamic diameter and minor coarse mode at sizes > 1 mum. (orig.)

  13. Impact of shear stress and pH changes on floc size and removal of dissolved organic matter (DOM).

    Science.gov (United States)

    Slavik, Irene; Müller, Susanne; Mokosch, Regina; Azongbilla, Joseph Abanga; Uhl, Wolfgang

    2012-12-01

    The impact of shear stress and increases in pH on the release of natural dissolved organic matter (DOM) from Fe-DOM and Al-DOM flocs was investigated for a high organic matter, low turbidity raw water by application of a dynamic extinction probe (DEP) and liquid chromatography organic carbon detection (LC-OCD). It was shown that high shear forces resulted in a breakage of Fe-DOM flocs. Re-growth took place during subsequent low shear phases. However, re-growth was limited. The flocs regained a size of about 50% of the size after initial coagulation. Cyclic shearing resulted in slower re-growth rates. A new insight was that when enough time was given, similar sizes of the re-grown flocs were regained. As shown by bulk DOC, only an insignificant release of DOM took place when flocs were exposed to shear. Increase in shear stress resulted in smaller flocs with higher specific outer surface area. However, DOM removal did not change. Thus, there was no increase in adsorption capacity due to floc breakage. Consequently, DOM must be adsorbed inside the amorphous flocs rather than on the outer surface. Also, as shear results in more compact flocs, compaction does not have an effect on DOM removal. A pH increase of 0.5, as it can happen during water treatment after coagulation, resulted in a release of DOM. Humic substances accounted for the largest proportion of total DOM released. The increase in pH did not affect floc size. Consequently, DOM removal is mainly governed by the dependence of DOM properties on pH with the final pH determining the degree of DOM removal and not the path on which this pH is reached. The physical properties of the flocs have no impact on DOM removal. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Distribution and sources of organic matter in size-fractionated nearshore sediments off the Barcelona city (NW Mediterranean)

    Science.gov (United States)

    Quirós-Collazos, Lucía; Pedrosa-Pàmies, Rut; Sanchez-Vidal, Anna; Guillén, Jorge; Duran, Ruth; Cabelloa, Patricia

    2017-04-01

    Continental shelves are recognized to play a key role in the biogeochemical cycle of carbon, linking terrestrial and marine carbon reservoirs. In this study we investigate the physical and biogeochemical processes that control the source, transport and fate of organic carbon (OC) in the continental shelf off Barcelona city, in the NW Mediterranean Sea. Surface sediment samples were collected from depths of 10-40 m during late summer and autumn 2012. Grain size and biogeochemical parameters such as OC, its stable isotope δ13C, total nitrogen (TN) and OC/TN ratios were analysed in size-fractionated sediments. The influence of environmental factors over the study area was determined using hydrological and oceanographic time series, together with video images of the Barcelona coast line and nearshore region. We have found a wide range of OC contents, from 0.13 to 8.68%, depending on water depth and sediment particle size. The highest OC concentration was always found in the clay fraction (63 μm) that contained terrestrial plant debris. Wave activity, discharge of the Besòs River and the ;Espigó de Ginebra; outfall were the main mechanisms controlling the sorting of sediments by their grain size and thus the distribution of OC in the inner shelf off Barcelona. In addition, we observed that the organic matter in clay particles was progressively degraded seawards, probably because these particles remain suspended in the water column much more time compared to those that are heavier and, therefore, they are exposed for longer time periods to oxygenated conditions. Both OC/TN ratios and δ13C values found suggest that the organic matter preserved was predominantly land supplied.

  15. Font size matters--emotion and attention in cortical responses to written words.

    Directory of Open Access Journals (Sweden)

    Mareike Bayer

    Full Text Available For emotional pictures with fear-, disgust-, or sex-related contents, stimulus size has been shown to increase emotion effects in attention-related event-related potentials (ERPs, presumably reflecting the enhanced biological impact of larger emotion-inducing pictures. If this is true, size should not enhance emotion effects for written words with symbolic and acquired meaning. Here, we investigated ERP effects of font size for emotional and neutral words. While P1 and N1 amplitudes were not affected by emotion, the early posterior negativity started earlier and lasted longer for large relative to small words. These results suggest that emotion-driven facilitation of attention is not necessarily based on biological relevance, but might generalize to stimuli with arbitrary perceptual features. This finding points to the high relevance of written language in today's society as an important source of emotional meaning.

  16. Intra-community spatial variability of particulate matter size distributions in southern California/Los Angeles

    Directory of Open Access Journals (Sweden)

    M. Krudysz

    2008-05-01

    Full Text Available Ultrafine particle (UFP number concentrations vary significantly on small spatial and temporal scales due to their short atmospheric lifetimes and multiplicity of sources. To determine UFP exposure gradients within a community, simultaneous particle number concentration measurements at a network of sites are necessary. Concurrent particle size distribution measurements aid in identifying UFP sources, while providing data to investigate local scale effects of both photochemical and physical processes on UFP. From April to December 2007, we monitored particle size distributions at 13 sites within 350 m to 11 km of each other in the vicinity of the Ports of Los Angeles and Long Beach using Scanning Mobility Particle Sizers (SMPS. Typically, three SMPS units were simultaneously deployed and rotated among sites at 1–2 week intervals. Total particle number concentration measurements were conducted continuously at all sites. Seasonal and diurnal size distribution patterns are complex, highly dependent on local meteorology, nearby PM sources, and times of day, and cannot be generalized over the study area nor inferred from one or two sampling locations. Spatial variation in particle number size distributions was assessed by calculating the coefficient of divergence (COD and correlation coefficients (r between site pairs. Results show an overall inverse relationship between particle size and CODs, implying that number concentrations of smaller particles (<40 nm differ from site to site, whereas larger particles tend to have similar concentrations at various sampling locations. In addition, variations in r values as a function of particle size are not necessarily consistent with corresponding COD values, indicating that using results from correlation analysis alone may not accurately assess spatial variability.

  17. Sibship size and educational attainment in peninsular Malaysia: do policies matter?

    Science.gov (United States)

    Pong, S L

    1997-01-01

    This study examines the effects of sibship size on secondary school attainment in Malaysia. Data were obtained from the 1989 Malaysian Second Family Life Survey among a sample of individuals aged 19-38 years in 1989 who were born during 1938-69. The sample included 1749 Malays, 1071 Chinese, and 523 Indians. Subsamples divided persons into those born during the period 1950-59 and those born during 1960-69. 98% of the sample had a primary education. Almost 66% had attained a secondary school education: 23% of Malays, 34% of Chinese, and 30% of Indians. 97% had at least one sibling. The percentage of non-Malays with a secondary school education (SSE) decreased with an increase in sibship size. Sibship size was unrelated to SSE among Malays. It is pointed out that the preferential policies were probably a stronger impetus for secondary attainment among Malays than sibship size. Finer analysis by cohort revealed that only in the cohort born during 1950-59 did sibship size have no significant effect on SSE. Sibship size had a significantly negative impact among children born during 1960-69 and the impact was greater for Malays than non-Malays. The magnitude of the effect for Malays was twice as large in the 1960-69 cohort as in the 1950-59 cohort, while the magnitude of the impact of sibship size for non-Malays was the same for both birth cohorts. Average sibship size for non-Malays declined sharply over time, while it remained stable for Malays. Logistic analysis revealed few differences between ethnic groups in the predicted probabilities for the 1950-59 cohort when individual and family factors were accounted for. Findings suggest that non-Malays' adjustment by decreasing their fertility or changing family resource allocations could not entirely compensate for increases in the cost of education or reductions in the return to education. The benefit was the closing of the gap between Malays and non-Malays with regard to children's likelihood of SSE.

  18. Mechanical support availability in pediatric cardiac surgery: program size should not matter.

    Science.gov (United States)

    da Cruz, Eduardo M; Beghetti, Maurice; Kalangos, Afksendyios; Berner, Michel; Sierra, Jorge; Aggoun, Yacine; Tissot, Cécile; Pellegrini, Michel; Saudan, Sonja; Habre, Walid; Rimensberger, Peter C

    2008-09-26

    Intractable heart failure may require Extracorporeal Life Support (ECLS) techniques for rescue therapy. Nevertheless, in many small to middle-sized centers in Europe, this valuable resource is not available. In our University pediatric intensive care unit 0.9% of 1360 open-heart surgical patients required mechanical assistance over the latest 9 years with a survival rate of 69.2% and low residual morbidity. This favorable overall outcome suggests that regardless of the program size, it is possible to ensure the availability of efficient mechanical assistance that appears to be fundamental in a center performing surgery for complex congenital or acquired cardiac diseases.

  19. Size-segregated particulate matter inside residences of elderly in the Metropolitan Area of São Paulo, Brazil

    Science.gov (United States)

    Segalin, Bruna; Kumar, Prashant; Micadei, Kaonan; Fornaro, Adalgiza; Gonçalves, Fabio L. T.

    2017-01-01

    The elderly population spend relatively more time indoors and is more sensitive to air pollution-related health risks but there is limited information on the quality of the air they breathe inside their residences. The objectives of this work are to (i) characterise mass of size-segregated particulate matter (PM) in elderly residences in Metropolitan Area of Sao Paulo (MASP) in Brazil, (ii) assess the impact of the meteorological parameters on the behaviour of indoor PM concentrations, (iii) evaluate the indoor and outdoor relationship of PM mass concentration, and (iv) estimate the respiratory deposition doses (RDD). To achieve these objectives, we measured mass concentrations of size-segregated particles in 59 elderly residences in MASP. The measurements were made in the 0.25-10 μm size range in 5 size bins using a Personal Cascade Impactor Sampler. We evaluated the mass concentration of particles using a gravimetric method and compared our PM10 (sum of all size bins) and PM2.5 (sum of all size bins, except PM10-2.5) concentrations against the 24 h mean guidelines recommended by World Health Organization (WHO). Our results show the mean PM10 and PM2.5 measured in elderly residences in MASP as 35.2 and 27.4 μg m-3, respectively. PM2.5 and PMtotal PM10, respectively, clearly suggesting a significantly high exposure to fine particles by the elderly. About 13 and 43% of the measurements exceeded the WHO's PM10 and PM2.5 guidelines, respectively. The samples were clustered into five groups to found the behaviour of indoor PM. The cluster representing the residences with higher PM concentration in all size bins are predominantly residences near the heavy traffic areas during the non-precipitation days. About 68% of residences showed the highest fraction of PMcontrol of indoor sources in the elderly residences to limit adverse health effects of particulate matter, especially fine particles, on elderly.

  20. Uncertainty driven probabilistic voxel selection for image registration.

    Science.gov (United States)

    Oreshkin, Boris N; Arbel, Tal

    2013-10-01

    This paper presents a novel probabilistic voxel selection strategy for medical image registration in time-sensitive contexts, where the goal is aggressive voxel sampling (e.g., using less than 1% of the total number) while maintaining registration accuracy and low failure rate. We develop a Bayesian framework whereby, first, a voxel sampling probability field (VSPF) is built based on the uncertainty on the transformation parameters. We then describe a practical, multi-scale registration algorithm, where, at each optimization iteration, different voxel subsets are sampled based on the VSPF. The approach maximizes accuracy without committing to a particular fixed subset of voxels. The probabilistic sampling scheme developed is shown to manage the tradeoff between the robustness of traditional random voxel selection (by permitting more exploration) and the accuracy of fixed voxel selection (by permitting a greater proportion of informative voxels).

  1. Size Matters: Economies of Scale in Schools and Colleges. Research Report

    Science.gov (United States)

    Owen, Glyn; Fletcher, Mick; Lester, Stan

    2006-01-01

    This report reviews the relationship in England between institutional size and the cost of Level 3 (mainly A-level) provision in three major settings: sixth form colleges (SFCs), general further education colleges (GFECs) and school sixth forms (SSFs). The study models how institutions might behave, given the funding regime and cost structures. It…

  2. Hubble Space Telescope NICMOS observations of the host galaxies of powerful radio sources : Does size matter?

    NARCIS (Netherlands)

    de Vries, WH; O'Dea, CP; Barthel, PD; Fanti, C; Fanti, R; Lehnert, MD

    2000-01-01

    We present near-infrared J- and K-band imaging of a sample of powerful radio source host galaxies with the Hubble Space Telescope NICMOS2 camera. These sources have been selected on their double-lobed radio structure and include a wide range of projected radio source sizes. The largest projected

  3. Small Size at Birth or Abnormal Intrauterine Growth Trajectory: Which Matters More for Child Growth?

    Science.gov (United States)

    Hutcheon, Jennifer A; Jacobsen, Geir W; Kramer, Michael S; Martinussen, Marit; Platt, Robert W

    2016-06-15

    Small size at birth is linked with lifelong adverse health implications. However, small size is only a proxy for the pathological process of interest, intrauterine growth restriction. We examined the extent to which information on intrauterine growth patterns improved prediction of childhood anthropometry, above and beyond birth weight alone. We obtained fetal weights estimated via serial ultrasound for 478 children in the Scandinavian Successive Small-for-Gestational-Age Births Study (1986-1988). Size at birth was classified using birth weight-for-gestational-age z scores and conditional fetal growth z scores (reflecting growth between 25 weeks' gestation and birth) using internal references. Conditional z scores were also expressed as residuals of birth weight z scores. Growth measures were linked with age-5-years anthropometric characteristics using linear regression. In univariable analyses, conditional fetal growth z scores were positively associated with z scores for child height, body mass index, total skinfold thickness, and head circumference (β = 0.24 (95% confidence interval (CI): 0.18, 0.31), β = 0.16 (95% CI: 0.09, 0.23), β = 0.08 (95% CI: 0.01, 0.16), and β = 0.37 (95% CI: 0.22, 0.52), respectively). However, conditional z scores were highly correlated with birth weight z scores (r = 0.9), and residuals explained minimal additional variation in anthropometric factors (null coefficients; adjusted R(2) increases child growth beyond that obtained from absolute size at birth.

  4. Does size matter? An investigation into the Rey Complex Figure in a pediatric clinical sample.

    Science.gov (United States)

    Loughan, Ashlee R; Perna, Robert B; Galbreath, Jennifer D

    2014-01-01

    The Rey Complex Figure Test (RCF) copy requires visuoconstructional skills and significant attentional, organizational, and problem-solving skills. Most scoring schemes codify a subset of the details involved in figure construction. Research is unclear regarding the meaning of figure size. The research hypothesis of our inquiry is that size of the RCF copy will have neuropsychological significance. Data from 95 children (43 girls, 52 boys; ages 6-18 years) with behavioral and academic issues revealed that larger figure drawings were associated with higher RCF total scores and significantly higher scores across many neuropsychological tests including the Wechsler Individual Achievement Test-Second Edition (WIAT-II) Word Reading (F = 5.448, p = .022), WIAT-II Math Reasoning (F = 6.365, p = .013), Children's Memory Scale Visual Delay (F = 4.015, p = .048), Trail-Making Test-Part A (F = 5.448, p = .022), and RCF Recognition (F = 4.862, p = .030). Results indicated that wider figures were associated with higher cognitive functioning, which may be part of an adaptive strategy in helping facilitate accurate and relative proportions of the complex details presented in the RCF. Overall, this study initiates the investigation of the RCF size and the relationship between size and a child's neuropsychological profile.

  5. Factors Affecting Teachers' Adoption of Technology in Classrooms: Does School Size Matter?

    Science.gov (United States)

    Wu, Hsin-Kai; Hsu, Ying-Shao; Hwang, Fu-Kwun

    2008-01-01

    Researchers in educational technology have searched for factors to explain teachers' acceptance and resistance to using technology for instruction. Among the many identified factors, however, organizational and school factors have not yet been explored and discussed. This study investigates the effects of school size on science and mathematics…

  6. Seeds, saplings and gaps: size matters. A study in the tropical rain forest of Guyana

    NARCIS (Netherlands)

    Rose, S.A.

    2001-01-01

    Forest management for timber exploitation is dependent on the succesful regeneration of commercial timber species in gaps. This study evaluated the influence of gap size and seed mass on the processes of seedling recruitment, establishment, growth and survival in logged over and mature forest

  7. Nanoparticle size matters in the formation of plasma protein coronas on Fe3O4 nanoparticles.

    Science.gov (United States)

    Hu, Zhengyan; Zhang, Hongyan; Zhang, Yi; Wu, Ren'an; Zou, Hanfa

    2014-09-01

    When nanoparticles (NPs) enter into biological systems, proteins would interact with NPs to form the protein corona that can critically impact the biological identity of the nanomaterial. Owing to their fundamental scientific interest and potential applications, Fe3O4 NPs of different sizes have been developed for applications in cell separation and protein separation and as contrast agents in magnetic resonance imaging (MRI), etc. Here, we investigated whether nanoparticle size affects the formation of protein coronas around Fe3O4 NPs. Both the identification and quantification results demonstrated that particle size does play an important role in the formation of plasma protein coronas on Fe3O4 NPs; it not only influenced the protein composition of the formed plasma protein corona but also affected the abundances of the plasma proteins within the coronas. Understanding the different binding profiles of human plasma proteins on Fe3O4 NPs of different sizes would facilitate the exploration of the bio-distributions and biological fates of Fe3O4 NPs in biological systems.

  8. Contrast-enhanced ultrasound of focal nodular hyperplasia: a matter of size

    Energy Technology Data Exchange (ETDEWEB)

    Bertin, Caroline [Hopital Beaujon APHP, Radiology Department, Clichy (France); Egels, Sophie; Huynh-Charlier, Isabelle [Hopital Pitie-Salpetriere APHP, Radiology Department, Paris (France); Wagner, Mathilde [Hopital Pitie-Salpetriere APHP, Radiology Department, Paris (France); Universite Paris Diderot, INSERM, UMR 1149, Laboratoire IPMA, Centre de Recherche sur l' Inflammation, Faculte de Medecine X Bichat, Paris (France); Vilgrain, Valerie [Hopital Beaujon APHP, Radiology Department, Clichy (France); Universite Paris Diderot, INSERM, UMR 1149, Laboratoire IPMA, Centre de Recherche sur l' Inflammation, Faculte de Medecine X Bichat, Paris (France); Lucidarme, Olivier [Hopital Pitie-Salpetriere APHP, Radiology Department, Paris (France); Sorbonne Universites, UPMC Univ Paris 06, CNRS UMR 7371, INSERM UMRS 1146, Laboratoire d' Imagerie Biomedicale, Paris (France); Groupe Hospitalier Pitie-Salpetriere - Charles Foix, Service de Radiologie Polyvalente et Oncologique, Paris (France)

    2014-10-15

    To assess the contrast-enhanced ultrasound (CEUS) frequencies of centrifugal enhancement, spoke-wheel sign and central scar in focal nodular hyperplasia (FNH) as a function of lesion size. Ninety-four FNHs were retrospectively reviewed to assess their largest diameter and enhancement pattern, including centrifugal enhancement from one central artery, spoke-wheel sign, diffuse or centripetal enhancement, central scar and late-phase washout. Mean FNH-lesion size was 3.7 ± 2.1 cm. Only 43.6 % of FNHs had centrifugal enhancement, with a spoke-wheel pattern (23.4 %) or without (20.2 %), while 56.4 % showed diffuse or centripetal enhancement. Centrifugal enhancement was observed in 73.9 % of FNHs ≤3.1 cm and 14.6 % of FNHs >3.1 cm (P < 10{sup -4}). Size and frequency of centrifugal enhancement were negatively correlated (r = -0.57, P < 10{sup -4}). The spoke-wheel pattern was also seen more frequently in smaller (37 %) than in larger FNHs (10.4 %) (P < 10{sup -3}). Late-phase washout was described in 5.3 % of FNHs and was not size-dependent. Lesions with a central scar were larger than those without, respectively, 5.7 ± 1.7 and 3.6 ± 2.0 cm (P = 0.012). Typical centrifugal enhancement yielding a confident FNH diagnosis is seen significantly more frequently when the lesion is ≤3.1 cm. (orig.)

  9. Whole brain CT perfusion in acute anterior circulation ischemia: coverage size matters

    Energy Technology Data Exchange (ETDEWEB)

    Emmer, B.J. [Erasmus Medical Centre, Department of Radiology, Postbus 2040, Rotterdam (Netherlands); Rijkee, M.; Walderveen, M.A.A. van [Leiden University Medical Centre, Department of Radiology, Leiden (Netherlands); Niesten, J.M.; Velthuis, B.K. [University Medical Centre Utrecht, Department of Radiology, Utrecht (Netherlands); Wermer, M.J.H. [Leiden University Medical Centre, Department of Neurology, Leiden (Netherlands)

    2014-12-15

    Our aim was to compare infarct core volume on whole brain CT perfusion (CTP) with several limited coverage sizes (i.e., 3, 4, 6, and 8 cm), as currently used in routine clinical practice. In total, 40 acute ischemic stroke patients with non-contrast CT (NCCT) and CTP imaging of anterior circulation ischemia were included. Imaging was performed using a 320-multislice CT. Average volumes of infarct core of all simulated partial coverage sizes were calculated. Infarct core volume of each partial brain coverage was compared with infarct core volume of whole brain coverage and expressed using a percentage. To determine the optimal starting position for each simulated CTP coverage, the percentage of infarct coverage was calculated for every possible starting position of the simulated partial coverage in relation to Alberta Stroke Program Early CT Score in Acute Stroke Triage (ASPECTS 1) level. Whole brain CTP coverage further increased the percentage of infarct core volume depicted by 10 % as compared to the 8-cm coverage when the bottom slice was positioned at the ASPECTS 1 level. Optimization of the position of the region of interest (ROI) in 3 cm, 4 cm, and 8 cm improved the percentage of infarct depicted by 4 % for the 8-cm, 7 % for the 4-cm, and 13 % for the 3-cm coverage size. This study shows that whole brain CTP is the optimal coverage for CTP with a substantial improvement in accuracy in quantifying infarct core size. In addition, our results suggest that the optimal position of the ROI in limited coverage depends on the size of the coverage. (orig.)

  10. Not only size matters: Acorn selection by the European jay ( Garrulus glandarius)

    Science.gov (United States)

    Pons, Josep; Pausas, Juli G.

    2007-05-01

    A strong selection for acorn characteristics is expected to have evolved in the mutualistic relationship between the European jay ( Garrulus glandarius) and the oak ( Quercus spp.). Bossema's pioneer work suggested that jays do not select acorns randomly, but rather they preferentially select some size and species. Preference for some seeds over others may have implications on plant community dynamics by conferring advantages (or disadvantages) on the selected (avoided) seed characteristics. In this paper we test to what extent jays select acorns by species and/or by size and the relation between these two traits in Mediterranean oak species. The experiments consist of a set of field tests in which acorns from four different coexisting Mediterranean oak species ( Quercus ilex, Quercus faginea, Quercus suber, and Quercus coccifera) were placed in artificial feeders accessible to wild jays. The acorns were previously measured to control individual acorn characteristics. Using video-recording techniques, we followed jay activity and the fate of each acorn (sequence of acorn selection and method of transport). Q. ilex acorns were preferred over other acorns, and Q. coccifera acorns were avoided when other acorns were available. Preference for Q. faginea and Q. suber acorns was intermediate, that is, they were preferred over Q. coccifera acorns but not over Q. ilex acorns. Large acorns were also preferred although acorn species selection was stronger than size selection. Jays selected species and size both by visual means and by using acorn area as an indicator of size. Acorns wider than 17-19 mm were carried in the bill because of throat limitation. Our results confirm Bossema's study on temperate oaks and extend it to Mediterranean oak species, revealing implications on mixed oak forest dynamics.

  11. Interplay of Natural Organic Matter with Flow Rate and Particle Size on Colloid Transport: Experimentation, Visualization, and Modeling.

    Science.gov (United States)

    Yang, Xinyao; Zhang, Yimeng; Chen, Fangmin; Yang, Yuesuo

    2015-11-17

    The investigation on factors that affect the impact of natural organic matter (NOM) on colloid transport in complex hydraulic flow systems remains incomplete. Using our previously established approach, the interplay of flow rate and particle size on the NOM effect was quantified, using flow rates of 1 and 2 mL/min and particle sizes of 50 and 200 nm to represent small nanoparticles (1-100 nm) and large non-nano-microspheres (100-1000 nm) in the low-flow groundwater environment. Latex particles, Suwannee River humic acid (SRHA), and iron oxide-coated sand were used as model particles, NOM, and the aquifer medium, respectively. The quantitative results show NOM blocked more sites for large particles at a high flow rate: 1 μg of SRHA blocked 5.95 × 10(9) microsphere deposition sites at 2 mL/min but only 7.38 × 10(8) nanoparticle deposition sites at 1 mL/min. The particle size effect dominated over the flow rate, and the overall effect of the two is antagonistic. Granule-scale visualization of the particle packing on the NOM-presented sand surface corroborates the quantification results, revealing a more dispersed status of large particles at a high flow rate. We interpret this phenomenon as a polydispersivity effect resulting from the differential size of the particles and NOM: high flow and a high particle size enlarge the ratio of particle-blocked to NOM-blocked areas and thus the NOM blockage. To our knowledge, this is the first model-assisted quantification on the interplay of NOM, flow rate, and particle size on colloid transport. These findings are significant for nanorisk assessment and nanoremediation practices.

  12. Trace elements in particulate matter from metropolitan regions of Northern China: Sources, concentrations and size distributions.

    Science.gov (United States)

    Pan, Yuepeng; Tian, Shili; Li, Xingru; Sun, Ying; Li, Yi; Wentworth, Gregory R; Wang, Yuesi

    2015-12-15

    Public concerns over airborne trace elements (TEs) in metropolitan areas are increasing, but long-term and multi-site observations of size-resolved aerosol TEs in China are still lacking. Here, we identify highly elevated levels of atmospheric TEs in megacities and industrial sites in a Beijing-Tianjin-Hebei urban agglomeration relative to background areas, with the annual mean values of As, Pb, Ni, Cd and Mn exceeding the acceptable limits of the World Health Organization. Despite the spatial variability in concentrations, the size distribution pattern of each trace element was quite similar across the region. Crustal elements of Al and Fe were mainly found in coarse particles (2.1-9 μm), whereas the main fraction of toxic metals, such as Cu, Zn, As, Se, Cd and Pb, was found in submicron particles (environmental standards in China are required to reduce the amounts of these hazardous pollutants released into the atmosphere.

  13. Dynamics of Dissolved Organic Matter and Microbes in Seawater through Sub-Micron Particle Size Analyses

    Digital Repository Service at National Institute of Oceanography (India)

    Goes, J.I.; Balch, W.M.; Vaughn, J.M.; Gomes, H.R.

    , 1997). In view of the above, understanding the processes regulating the dynamics and distribution of DOM in seawater, assumes tremendous importance for global biogeochemistry and climate change studies. Phytoplankton are the primary source of oceanic.... The exact relationship between the lift force and the channel flow velocity is not well- characterized and calibrations with standard monodispersed particles (>1?m) are necessary to calibrate an FFFF fractogram into a size distribution plot. The FFFF...

  14. Vestibular function and quality of life in vestibular schwannoma: does size matter?

    Directory of Open Access Journals (Sweden)

    Judith eWagner

    2011-08-01

    Full Text Available Objectives. Patients with vestibular schwannoma (VS frequently suffer from disabling vestibular symptoms. This prospective follow-up study evaluates vestibular and auditory function and impairment of quality of life due to vertigo, dizziness and imbalance in patients with unilateral vestibular schwannoma of different sizes before/ after microsurgical or radiosurgical treatment. Methods. 38 patients with unilateral vestibular schwannoma were included. 22 received microsurgery, 16 cyberknife radiosurgery. Two follow-ups took place after a median of 50 and 186.5 days. Patients received a standardized neuro-ophthalmological examination, electronystagmography with bithermal caloric testing, and pure-tone audiometry. Quality of life was evaluated with the Dizziness Handicap Inventory (DHI. Patient data was grouped and analyzed according to the size of the VS (group 1: < 20mm vs group 2: ≥ 20mm. Results. In group 1, the median loss of vestibular function was +10.5% as calculated by Jongkees Formula (range –43;+52; group 2: median + 36%, range –56; +90. The median change of DHI scores was –9 in group 1 (range –68;30 and +2 in group 2 (–54;+20. Median loss of hearing was 4dB (-42;93 in group 1 and 12dB in group 2 (5;42.Conclusions. Loss of vestibular function in vestibular schwannoma clearly correlates with tumor size. However, loss of vestibular function was not strictly associated with a long-term deterioration of quality of life. This may be due to central compensation of vestibular deficits in long-standing large tumors. Loss of hearing before treatment was significantly influenced by the age of the patient but not by tumor size. At follow-up 1 and 2, hearing was significantly worse in those patients with a large VS and after microsurgical treatment.

  15. Seeds, saplings and gaps: size matters. A study in the tropical rain forest of Guyana

    OpenAIRE

    Rose, S A

    2001-01-01

    Forest management for timber exploitation is dependent on the succesful regeneration of commercial timber species in gaps. This study evaluated the influence of gap size and seed mass on the processes of seedling recruitment, establishment, growth and survival in logged over and mature forest areas over four years (1996-1999) in the tropical rain forest in Guyana. It generates insight into the potential impacts of logging on forest species diversity, and indicates necessary management procedu...

  16. The Impact of Lean bundles on Hospital Performance, Does Size Matter?

    OpenAIRE

    Al-Hyari, K.; Abuhammour, S.; Abu Zaid, M.; Haffar, Mohamed

    2016-01-01

    Purpose\\ud The purpose of this paper is to study the effect of the implementation of Lean bundles on hospital performance in private hospitals in Jordan and evaluate how much the size of organization can affect the relationship between Lean bundles implementation and hospital performance.\\ud Design/methodology/approach\\ud The research is considered as quantitative method (descriptive and hypothesis testing). Three statistical techniques were adopted to analyse the data. Structural equation mo...

  17. When problem size matters: differential effects of brain stimulation on arithmetic problem solving and neural oscillations.

    Directory of Open Access Journals (Sweden)

    Bruno Rütsche

    Full Text Available The problem size effect is a well-established finding in arithmetic problem solving and is characterized by worse performance in problems with larger compared to smaller operand size. Solving small and large arithmetic problems has also been shown to involve different cognitive processes and distinct electroencephalography (EEG oscillations over the left posterior parietal cortex (LPPC. In this study, we aimed to provide further evidence for these dissociations by using transcranial direct current stimulation (tDCS. Participants underwent anodal (30min, 1.5 mA, LPPC and sham tDCS. After the stimulation, we recorded their neural activity using EEG while the participants solved small and large arithmetic problems. We found that the tDCS effects on performance and oscillatory activity critically depended on the problem size. While anodal tDCS improved response latencies in large arithmetic problems, it decreased solution rates in small arithmetic problems. Likewise, the lower-alpha desynchronization in large problems increased, whereas the theta synchronization in small problems decreased. These findings reveal that the LPPC is differentially involved in solving small and large arithmetic problems and demonstrate that the effects of brain stimulation strikingly differ depending on the involved neuro-cognitive processes.

  18. Mg/Ca and δ18O in the calcite of benthic foraminifera: does size matter?

    Science.gov (United States)

    de Nooijer, Lennart; Bijma, Jelle; -Jan Reichart, Gert; Hathorne, Ed

    2010-05-01

    Mg/Ca and del-18O are popular proxies for past sea water temperatures, ice volume and, together, salinity. The biological control that foraminifera have over calcification results in precipitation of calcium carbonate that has an isotope and element composition that is very different from those of inorganically precipitated calcium carbonates. Indications for an effect of ontogeny (i.e. size of a specimen) on the fractionation of oxygen isotopes are contradictory, while for the incorporation of most (trace) elements, data are lacking. The causes of size-based variability in element incorporation and isotope fractionation need to be understood and quantified in order to reliably use them as paleoproxies. In this study, we present Mg/Ca and oxygen isotope data from cultured specimens of the benthic foraminifer Ammonia tepida. When asexual reproduction takes place in this species, 50-300 genetically identical juveniles (i.e. clones) are produced. These juveniles are cultured at constant temperature, carbonate chemistry, salinity, etc to determine inter- and intra-specimen variability in Mg/Ca, Ba/Ca and Sr/Ca. From the same groups of clones, del-18O was determined from specimens with different sizes. Results show that the variability differs greatly between the analysed elements (e.g. relatively constant for Sr and Ba, variable for Mg) and isotopes, underscoring the need for a biological understanding of foraminiferal calcification pathways.

  19. Size-resolved source apportionment of particulate matter in urban Beijing during haze and non-haze episodes

    Science.gov (United States)

    Tian, S. L.; Pan, Y. P.; Wang, Y. S.

    2016-01-01

    Additional size-resolved chemical information is needed before the physicochemical characteristics and sources of airborne particles can be understood; however, this information remains unavailable in most regions of China due to lacking measurement data. In this study, we report observations of various chemical species in size-segregated particle samples that were collected over 1 year in the urban area of Beijing, a megacity that experiences severe haze episodes. In addition to fine particles, high concentrations of coarse particles were measured during the periods of haze. The abundance and chemical compositions of the particles in this study were temporally and spatially variable, with major contributions from organic matter and secondary inorganic aerosols. The contributions of organic matter to the particle mass decreased from 37.9 to 31.2 %, and the total contribution of sulfate, nitrate and ammonium increased from 19.1 to 33.9 % between non-haze and haze days, respectively. Due to heterogeneous reactions and hygroscopic growth, the peak concentrations of the organic carbon, cadmium and sulfate, nitrate, ammonium, chloride and potassium shifted from 0.43 to 0.65 µm on non-haze days to 0.65-1.1 µm on haze days. Although the size distributions of lead and thallium were similar during the observation period, their concentrations increased by a factor of more than 1.5 on haze days compared with non-haze days. We observed that sulfate and ammonium, which have a size range of 0.43-0.65 µm, sulfate and nitrate, which have a size range of 0.65-1.1 µm, calcium, which has a size range of 5.8-9 µm, and the meteorological factors of relative humidity and wind speed were responsible for haze pollution when the visibility was less than 10 km. Source apportionment using Positive Matrix Factorization showed six PM2.1 sources and seven PM2.1-9 common sources: secondary inorganic aerosol (25.1 % for fine particles vs. 9.8 % for coarse particles), coal combustion (17

  20. Ciguatera fish toxicity in French Polynesia: size does not always matter.

    Science.gov (United States)

    Gaboriau, Matthias; Ponton, Dominique; Darius, H Taiana; Chinain, Mireille

    2014-06-01

    Accumulation of ciguatoxins (CTXs) in tropical reef fish tissues during their life is responsible of the most prevalent human seafood intoxication in the South Pacific called Ciguatera Fish Poisoning (CFP). It has been assumed for a long time that CTXs are transferred and accumulated along the trophic food chain, and consequently that smaller individuals within a given fish species are safer to eat than larger ones. However, the relationship between toxicity and fish size has been studied for a limited number of species only and the conclusions are often contradictory. The toxicity of 856 fishes from 59 different species sampled in six islands in French Polynesia between 2003 and 2011 was assessed by Receptor Binding Assay. Among them, 45 species × island and 32 families × island for which the number of individuals was ≥6 allowed testing the relationship between toxicity and size. Except for six specimens of Lutjanus bohar caught in Fakarava (P < 0.01; R(2) = 0.854), the 44 remaining species × island showed no significant increase of CTXs concentration with fish total length (TL). Moreover, the proportion of toxic individuals decreased significantly for Epinephelus polyphekadion from Fakarava (n = 24; P < 0.05) and Kyphosus cinerascens from Raivavae (n = 29; P < 0.05), while no significant variation was detected for the other 43 species × island. At the family level, only three positive and three negative relationships between size and CTXs concentration were observed among the 32 family × island analyzed. No relationship between the proportion of toxic fish within a family and the relative total length of individuals were observed. The lack of relationship between toxicity and size observed for most of the species and families from the six islands suggests that fish size cannot be used as an efficient predictor of fish toxicity in French Polynesia. These results highlight the need for improving our knowledge about metabolic processes

  1. 轻度认知损害和阿尔茨海默病的大脑灰质体积及其与记忆功能的关系%Relationship between the brain gray matter volume and memory performance in mild cognitive impairment and Alzheimer' s disease: a voxel-based morphometric study

    Institute of Scientific and Technical Information of China (English)

    何毅; 王华丽; 苏敏莹; 袁慧书; 李涛; 张美燕; 于欣

    2012-01-01

    Objective To explore the relationship between the gray matter loss measured with voxel-based morphometry (VBM) and memory performance in mild cognitive impairment (MCI) and Alzheimer's disease (AD). Methods Eighty-six subjects were recruited, including 56 patients with mild AD, 14 subjects with MCI, and 16 healthy controls. All subjects were administered the comprehensive memory tests, All 3D T1 images were analyzed by using the procedures of optimized VBM analysis. Results Compared to control group, memory performance were significantly worse in AD and MCI groups, in a pattern of AD < MCI < control. Gray matter loss was detected extensively in the temporal, frontal and parietal lobes in AD group. There was More severe atrophy in frontal and parietal lobes in AD compared to MCI group. In AD group, the 3D statistical maps showed extensive cortical areas in the temporal, frontal and parietal lobes were linked to immediate object memory performance. Score of 30-min delayed recall of objects was correlated strongly with the gray matter density in the bilateral superior frontal gyri, thalamus, right anterior cingulate, medial frontal gyri, middle temporal gyri, and paracentral lobule (P < 0.01). Composite memory score was closely correlated with the gray matter density in the left parahippocampal gyrus, middle temporal gyri, precuneus, superior frontal gyri, middle frontal gyri, cingulate gyrus, and right parahippocampal gyrus, medial frontal gyri, and inferior frontal gyri (P < 0.01). In MCI and NC groups, suprathreshold clusters were not correlated with the memory scores. Conclusion Memory impairment is strongly correlated with extensive cerebral atrophy in AD. Brain volume in MCI individuals are not significantly correlated with memory performance, suggesting that memory impairment, an early sign of MCI, may not be directly attributable to brain atrophy. Further investigations on microstructural or functional connectivity are warranted.%目的

  2. Particulate matter and atherosclerosis: role of particle size, composition and oxidative stress

    Directory of Open Access Journals (Sweden)

    Nel Andre E

    2009-09-01

    Full Text Available Abstract Air Pollution has been associated with significant adverse health effects leading to increased morbidity and mortality. Cumulative epidemiological and experimental data have shown that exposure to air pollutants lead to increased cardiovascular ischemic events and enhanced atherosclerosis. It appears that these associations are much stronger with the air particulate matter (PM component and that in urban areas, the smaller particles could be more pathogenic, as a result of their greater propensity to induce systemic prooxidant and proinflammatory effects. Much is still unknown about the toxicology of ambient particulates as well as the pathogenic mechanisms responsible for the induction of adverse cardiovascular health effects. It is expected that better understanding of these effects will have large implications and may lead to the formulation and implementation of new regulatory policies. Indeed, we have found that ultrafine particles ( Extensive epidemiological evidence supports the association of air pollution with adverse health effects 123. It is increasingly being recognized that such effects lead to enhanced morbidity and mortality, mostly due to exacerbation of cardiovascular diseases and predominantly those of ischemic character 4. Indeed, in addition to the classical risk factors such as serum lipids, smoking, hypertension, aging, gender, family history, physical inactivity and diet, recent data have implicated air pollution as an important additional risk factor for atherosclerosis. This has been the subject of extensive reviews 56 and a consensus statement from the American Heart Association 7. This article reviews the supporting epidemiological and animal data, possible pathogenic mechanisms and future perspectives.

  3. Chemical composition and size distribution of airborne particulate matters in Beijing during the 2008 Olympics

    Science.gov (United States)

    Li, Xingru; Wang, Lili; Wang, Yuesi; Wen, Tianxue; Yang, Yongjie; Zhao, Yanan; Wang, Yingfeng

    2012-04-01

    Size-segregated aerosol samples were collected daily in Beijing from 1 Jun. to 20 Sep. during the Beijing Olympic Games in 2008 to investigate aerosol concentrations, particle size distributions, and sources as well as the effects of pollution control measures on the chemical compositions (including Water-soluble ions, trace elements, elemental carbon (EC), and organic carbon (OC)) in aerosols of different sizes. Water-soluble ions, EC, OC, and trace elements accounted for 45.0%, 1.6%, 14.7%, and 11.4% of the total particle mass (PM), respectively. Approximately 56%, 56%, 30%, 71% and 55% of the PM, water-soluble ions, trace elements, EC and OC, respectively, were associated with particles smaller than 2.1 μm. Sulfate, nitrate, and ammonium were the dominant ions, which together accounted for approximately 77% of total water-soluble ions. The crustal elements accounted for the majority of the trace elements present. Different sources showed different mass size distributions. Anthropogenic source compounds, such as sulfate, nitrate, ammonium, OC, EC, and toxic elements, were mainly present in fine mode aerosols, whereas crustal elements, such as Al, Fe, Ca, Mg and Ba, primarily occurred in the coarse mode. SO42- and NH4+ concentrations were strongly correlated (r2 = 0.90, slope = 1.63) in the fine mode, thereby indicating that SO42- was mainly present as (NH4)2SO4; in contrast, a weak correlation between SO42- and NH4+ (r2 = 0.18, slope = 0.54) was observed in the coarse mode, indicating that SO42- was associated with other ions. Similarly, SO42- and NO3- exhibited a stronger correlation in the fine mode than in the coarse mode, indicating that SO42- and NO3- were formed via the same in-cloud processes in fine particles. The OC/EC ratio and the correlations between EC and OC concentrations showed that the sources of carbonaceous species were secondary organic carbon from fine particles and the long-range transport of coarse carbonaceous particles from biomass

  4. Modeling and analysis of caves using voxelization

    Science.gov (United States)

    Szeifert, Gábor; Szabó, Tivadar; Székely, Balázs

    2014-05-01

    Although there are many ways to create three dimensional representations of caves using modern information technology methods, modeling of caves has been challenging for researchers for a long time. One of these promising new alternative modeling methods is using voxels. We are using geodetic measurements as an input for our voxelization project. These geodetic underground surveys recorded the azimuth, altitude and distance of corner points of cave systems relative to each other. The diameter of each cave section is estimated from separate databases originating from different surveys. We have developed a simple but efficient method (it covers more than 99.9 % of the volume of the input model on the average) to convert these vector-type datasets to voxels. We have also developed software components to make visualization of the voxel and vector models easier. Since each cornerpoint position is measured relative to another cornerpoints positions, propagation of uncertainties is an important issue in case of long caves with many separate sections. We are using Monte Carlo simulations to analyze the effect of the error of each geodetic instrument possibly involved in a survey. Cross-sections of the simulated three dimensional distributions show, that even tiny uncertainties of individual measurements can result in high variation of positions that could be reduced by distributing the closing errors if such data are available. Using the results of our simulations, we can estimate cave volume and the error of the calculated cave volume depending on the complexity of the cave. Acknowledgements: the authors are grateful to Ariadne Karst and Cave Exploring Association and State Department of Environmental and Nature Protection of the Hungarian Ministry of Rural Development, Department of National Parks and Landscape Protection, Section Landscape and Cave Protection and Ecotourism for providing the cave measurement data. BS contributed as an Alexander von Humboldt Research

  5. 采用优化的基于体素的形态学方法研究智力障碍儿童脑灰质容积变化%Investigation of the alteration of gray matter volume in children with mental retardation with the optimal voxel-based morphometry

    Institute of Scientific and Technical Information of China (English)

    袁新宇; 谢晟; 肖江喜; 张远哲; 蒋学祥; 金春华; 白振华; 仪晓立

    2011-01-01

    Objective To detect brain structural difference between children with unexplained mental retardation and children with typically normal development. Methods The high-resolution magnetic MR imaging were obtained from 21 children with unexplained mental retardation and 30 age-matched control children without intellectual disabilities. Voxel-based morphometry analysis with an optimization of spatial segmentation and normalization procedures were applied to compare differences of gray matter volume between the two groups. The total and regional gray matter volume were compared between the two groups with independent t test. Meanwhile, correlation was conducted to analyze the relationship between the total gray matter volume and intelligence quotient (IQ) with partial correlation test. Results The total gray matter volume was significantly increased in the mental retardation children [(1. 012 ±0. 079) × 106 mm3]in relative to the controls [(0. 956 ± 0. 059) × 106 mm3, t = - 2. 80, P < 0. 05]. Compared to controls,children with unexplained mental retardation showed significantly increased gray matter volume in different regions, including the bilateral thalami, the bilateral superior frontal gyri, the bilateral gyri rectus, the bilateral temporal poles, the right inferior frontal gyrus, right parahippocampal gyrus and the right cerebellum. No correlation was detected between the total gray matter volume and IQ in children with mental retardation (r = 0. 078 ,P > 0. 05). Conclusions VBM would detect the gray matter abnormalities that were not founded in routine MR scanning. The increase of gray matter volume in the frontal-thalamus network might indicate the delayed maturation of the brain development. This might be one of the causations of mental retardation in children.%目的 利用优化的基于体素的形态测量学(VBM)方法,比较病因不明且常规影像检查正常的智力障碍儿童与正常同龄儿童脑灰质容积的差异,探究患儿脑灰

  6. 应用体素的形态学研究复发缓解型多发性硬化患者的全脑灰质萎缩特点%Feature of grey matter atrophy in relapsing-remitting multiple sclerosis:a voxel-based morphometry Study

    Institute of Scientific and Technical Information of China (English)

    段云云; 李坤成; 刘亚欧; 梁佩鹏; 贾秀琴; 于春水; 秦文; 叶静; 孙慧

    2011-01-01

    Objective To investigate the feature of regional grey matter volume changes in relapsing-remitting multiple sclerosis (RRMS) patients by voxel-based morphometry ( VBM) and presume the possible pathophysiological basis.Methods Conventional magnetic resonance imaging (MRI) and T1-weighted three-dimensional MRI were obtained from 32 RRMS and 32 sex- and age-matched normal controls.The comparison of grey matter volume between the two groups was analyzed by statistical analysis software SPM5 and VBM.A Pearson correlational analysis was used to assess correlation between gre matter loss and disease duration,expanded disability status scale (EDSS) and visible brain lesion volume.Results Compared with normal controls,RRMS patients had extensive bilateral grey matter atrophy in thalami (left 2031 and right 1711),caudate (left 815 and right 1031) and parahippocampal gyrus (left 313 and right 467),as well as several cortical regions in frontal,temporal,parietal,and occipital lobes (t value were between 8.853 and 11.163,all P < 0.01).Regional grey matter loss in bilateral thalami ( r value were - 0.596 on left and were - 0.694 on right) and right caudate ( r = - 0.409 ) were strongly negatively correlated with visible brain lesion volume in RRMS (all P < 0.05 ).Conclusions By means of VBM,extensive grey matter atrophy are found in RRMS patients,especially in deep grey matter.Axonal degeneration secondary to visible brain lesions may be a key pathogenesis of grey matter atrophy in RRMS.%目的 利用基于体素的形态学研究方法比较复发缓解型多发性硬化(relapsingremitting multiple selerosis,RRMS)患者和健康志愿者局部脑灰质的体积差异,推断灰质体积变化可能的病理生理机制.方法 对32例RRMS患者和32名性别、年龄匹配的健康志愿者进行常规MRI和三维T1WI扫描,采用参数统计软件包SPM5进行图像后处理,对RRMS组及对照组数据进行基于体素的统计学比较.利用相

  7. Epidemiology of Injuries in High School Football: Does School Size Matter?

    Science.gov (United States)

    King, Harold; Campbell, Stephen; Herzog, Makenzie; Popoli, David; Reisner, Andrew; Polikandriotis, John

    2015-08-01

    More than 1 million US high school students play football. Our objective was to compare the high school football injury profiles by school enrollment size during the 2013-2014 season. Injury data were prospectively gathered on 1806 student athletes while participating in football practice or games by certified athletic trainers as standard of care for 20 high schools in the Atlanta Metropolitan area divided into small (football season. Smaller schools had a higher overall injury rate (79.9 injuries per 10,000 athletic exposures vs. 46.4 injuries per 10,000 athletic exposures; P injuries (14.3% vs. 10.3%; P = .009 and 3.5% vs. 1.5%; P = .006, respectively) while larger schools have more hip/upper leg injuries (13.3% vs. 9.9%; P = .021). Lastly, smaller schools had a higher concussion distribution for offensive lineman (30.6% vs. 13.4%; P = .006) and a lower rate for defensive backs/safeties (9.2% vs. 25.4%; P = .008). This study is the first to compare and show unique injury profiles for different high school sizes. An understanding of school specific injury patterns can help drive targeted preventative measures.

  8. The impact of Lean bundles on hospital performance: does size matter?

    Science.gov (United States)

    Al-Hyari, Khalil; Abu Hammour, Sewar; Abu Zaid, Mohammad Khair Saleem; Haffar, Mohamed

    2016-10-10

    Purpose The purpose of this paper is to study the effect of the implementation of Lean bundles on hospital performance in private hospitals in Jordan and evaluate how much the size of organization can affect the relationship between Lean bundles implementation and hospital performance. Design/methodology/approach The research is considered as quantitative method (descriptive and hypothesis testing). Three statistical techniques were adopted to analyse the data. Structural equation modeling techniques and multi-group analysis were used to examine the research's hypothesis, and to perform the required statistical analysis of the data from the survey. Reliability analysis and confirmatory factor analysis were used to test the construct validity, reliability and measurement loadings that were performed. Findings Lean bundles have been identified as an effective approach that can dramatically improve the organizational performance of private hospitals in Jordan. Main Lean bundles - just in time, human resource management, and total quality management are applicable to large, small and medium hospitals without significant differences in advantages that depend on size. Originality/value According to the researchers' best knowledge, this is the first research that studies the impact of Lean bundles implementation in healthcare sector in Jordan. This research also makes a significant contribution for decision makers in healthcare to increase their awareness of Lean bundles.

  9. Biogeography of soil organic matter molecular structure across multiple soil size fractions

    Science.gov (United States)

    Meier, C. L.; Neff, J.

    2009-12-01

    Recent work suggests that there is a common soil decomposition sequence whereby plant inputs are metabolized into a physiologically constrained set of compounds originating from microbes that may persist in soil over relatively long time-scales. Plant inputs tend to be found in coarse particulate fractions (>180 μm) with relatively fast turnover times, while microbially derived compounds tend to accrue in the finer silt + clay fractions (coniferous, temperate deciduous, dry desert/savannah, and tropical forest). We hypothesized that: 1) regardless of biome, fractions >180 μm would be chemically similar, and would be characterized by lignin and other plant-derived compounds; and 2) fractions 180 μm fractions (p180 μm coarse particulate fractions also contained compounds associated with microbial origins, indicating that microbial C is not limited to <53 μm size fractions. The PCA also revealed that samples within each of the three size fractions did not cluster together (i.e. they did not share a common molecular structure), but we did note that: 1) cold alpine and sub-alpine sites were unique and chemically similar; and 2) tropical forest soils were unique and chemically similar. Moreover, we observed large differences in molecular structure for dry desert/savannah sites with varying vegetation types (trees vs. grass) and varying geologic substrates. Taken together, these observations argue that temperature, vegetation, and underlying geology influence soil molecular structure, but support for a common decomposition sequence is mixed.

  10. Compressing Color Data for Voxelized Surface Geometry.

    Science.gov (United States)

    Dolonius, Dan; Sintorn, Erik; Kampe, Viktor; Assarsson, Ulf

    2017-08-18

    We explore the problem of decoupling color information from geometry in large scenes of voxelized surfaces and of compressing the array of colors without introducing disturbing artifacts. In this extension of our I3D paper with the same title, we first present a novel method for connecting each node in a sparse voxel DAG to its corresponding colors in a separate 1D array of colors, with very little additional information stored to the DAG. Then, we show that by mapping the 1D array of colors onto a 2D image using a space-filling curve, we can achieve high compression rates and good quality using conventional, modern, hardware-accelerated texture compression formats such as ASTC or BC7. We additionally explore whether this method can be used to compress voxel colors for off-line storage and network transmission using conventional off-line compression formats such as JPG and JPG2K. For real-time decompression, we suggest a novel variable bitrate block encoding that consistently outperforms previous work, often achieving two times the compression at equal quality.

  11. Optimization of Voxelization Parameters in Geant4 Tracking and Improvement of the Shooter Benchmarking Program

    CERN Document Server

    Siegel, Zachary

    2013-01-01

    The geometry-based tracking of the ubiquitous particle physics simulation toolkit Geant4 utilizes the idea of voxels, which effectively partition regions into multi-dimensional slices that can decrease simulation time. The extent of voxelization and the size of the voxels is determined by a set of parameters, which until now, defaulted to arbitrary numbers. In this report I document how I tested different values for these parameters and determined which values should be the default. I modified the existing G01 Geant4 example program to get an initial look at how the performance depended on the parameters. Then I modified the Shooter benchmark program, which lacks extraneous physics processes, to collect more refined data and to provide a tool for future testers to perform comprehensive benchmarks. To this end, I created a new geometry, added features to aid in testing over ranges of parameters, and setup the default tests to provide a good sampling of different simulation scenarios.

  12. A macromolecular crowding study of RNA folding and activity: polymer pore size matters! (Conference Presentation)

    Science.gov (United States)

    Börner, Richard; Fiorini, Erica; Paudel, Bishnu; Rueda, David; Sigel, Roland K. O.

    2016-03-01

    Catalytic RNAs, like the group IIB intron ribozyme of S. cerevesiae, require a high magnesium(II) concentration to show folding and function in vitro [1]. In contrast, in vivo conditions are characterized by a highly crowded cellular environment and much lower ion concentration. Molecular crowding agents are a widespread tool to mimic cellular crowding [2]. However, particular physical/chemical properties explaining the crowders influence are mostly not understood. In this study, we gain new insights on how polymer properties like viscosity, pore size etc. influence the activity and folding of a large RNA. We combined bulk activity assays and single-molecule Förster Resonance Energy Transfer experiments, screening the PEG volume fraction (%) and molecular weight (MW). Our results revealed that upon the influence of crowding agents, a compaction of the underlying structure depends on the PEG % and the presence of different PEG MW and % unveiled an optimal pore size in terms of catalytic activity. In summary, an increasing density of the crowding environment shifts the RNA towards the most compact state, but the ribozyme is only active if the crowders network matches its size [4]. We interpret the most compact state as necessary, but not sufficient, to keep the ribozyme active. Financial support from the European Research Council (MIRNA N° 259092, to RKOS), the Swiss National Fund (SNF), and the Forschungskredit Grant of the University of Zürich (FK-14-096 and 15-092 to RB) are gratefully acknowledged. [1] Swisher J.F., Su L.J., Brenowitz M., Anderson V.E., Pyle A.M., J. Mol. Bio., 315, 297-310 (2002). [2] Kilburn D., Roh J.H., Guo L., Briber R.M., Woodson S.A., JACS, 132, 8690-6 (2010). [3] Steiner M., Karunatilaka K.S., Sigel R.K.O., Rueda D., Proc. Natl. Acad. Sci. U.S.A.,105, 13853-8 (2008). [4] aBörner R, Fiorini E, Sigel R.K.O., Chimia, 69, 207-212 (2015).; bFiorini E., Paudel B., Börner R., Rueda D., Sigel R.K.O., submitted. [5] König S.L.B., Hadzic M

  13. Assessment of Contribution of Contemporary Carbon Sources to Size-Fractionated Particulate Matter and Time-Resolved Bulk Particulate Matter Using the Measurement of Radiocarbon

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, H M; Young, T M; Buchholz, B A

    2009-04-16

    This study was motivated by a desire to improve understanding of the sources contributing to the carbon that is an important component of airborne particulate matter (PM). The ultimate goal of this project was to lay a ground work for future tools that might be easily implemented with archived or routinely collected samples. A key feature of this study was application of radiocarbon measurement that can be interpreted to indicate the relative contributions from fossil and non-fossil carbon sources of atmospheric PM. Size-resolved PM and time-resolved PM{sub 10} collected from a site in Sacramento, CA in November 2007 (Phase I) and March 2008 (Phase II) were analyzed for radiocarbon and source markers such as levoglucosan, cholesterol, and elemental carbon. Radiocarbon data indicates that the contributions of non-fossil carbon sources were much greater than that from fossil carbon sources in all samples. Radiocarbon and source marker measurements confirm that a greater contribution of non-fossil carbon sources in Phase I samples was highly likely due to residential wood combustion. The present study proves that measurement of radiocarbon and source markers can be readily applied to archived or routinely collected samples for better characterization of PM sources. More accurate source apportionment will support ARB in developing more efficient control strategies.

  14. The rarity of Dark Matter Halos in medium-sized walls of the cosmic web

    Science.gov (United States)

    Goh, Tze; Primack, Joel R.; Lee, Christoph; Aragon-Calvo, Miguel A.; Behroozi, Peter

    2017-01-01

    In 2014, Marshall McCall mapped out our Local Sheet, the cosmic wall containing the Milk Way and Andromeda galaxies. We use the large new Bolshoi-Planck cosmological simulation to investigate how rare our type of Local Sheet is, with 2 nearby halos like those of Milky Way and Andromeda. The conclusion of our investigation is that the occurrence of a pair of galaxies the size of Milky Way and Andromeda near the center of a wall 8 mpc in diameter, with the pair of galaxies within 0.7 mpc/h of each other, is very rare : it makes up only 0.05% of all walls in the simulation.

  15. Size Matters: Developing Design Rules to Engineer Nanoparticles for Solid Tumour Targeting

    Science.gov (United States)

    Sykes, Edward Alexander

    Nanotechnology enables the design of highly customizable platforms for producing minimally invasive and programmable strategies for cancer diagnosis and treatment. Advances in this field have demonstrated that nanoparticles can enhance specificity of anti-cancer agents, respond to tumour-specific cues, and direct the visualization of biological targets in vivo. . Nanoparticles can be synthesized within the 1 to 100 nm range to achieve different electromagnetic properties and specifically interact with biological tissues by tuning their size, shape, and surface chemistry. However, it remains unclear which physicochemical parameters are critical for delivering nanomaterials to the tumour site. With less than 5% of administered nanoparticles reaching the tumour, engineering of nanoparticles for effective delivery to solid tumours remains a critical challenge to cancer nanomedicine. A more comprehensive understanding of the interplay between the nanomaterial physicochemical properties and biological systems is necessary to enhance the efficacy of nanoparticle tumour targeting. This thesis explores how nanoparticle size and functionalization with cancer cell specific agents impact nanoparticle delivery to tumours. Furthermore, this doctoral work (i) discusses how tumour structure evolves with growth, (ii) elucidates how such changes modulate nanoparticle accumulation, and (iii) identifies how the skin serves as a significant off-target site for nanoparticle uptake. This thesis also demonstrates the utility of empirically-derived parametric models, Monte Carlo simulations, and decision matrices for mechanistically understanding and predicting the impact of nanomaterial features and tumour biology on nanoparticle fate in vivo. These topics establish key design considerations to tailor nanoparticles for enhanced tumour targeting. Collectively, the concepts presented herein form a fundamental framework for the development of personalized nanomedicine and nano

  16. Computer simulations for internal dosimetry using voxel models.

    Science.gov (United States)

    Kinase, Sakae; Mohammadi, Akram; Takahashi, Masa; Saito, Kimiaki; Zankl, Maria; Kramer, Richard

    2011-07-01

    In the Japan Atomic Energy Agency, several studies have been conducted on the use of voxel models for internal dosimetry. Absorbed fractions (AFs) and S values have been evaluated for preclinical assessments of radiopharmaceuticals using human voxel models and a mouse voxel model. Computational calibration of in vivo measurement system has been also made using Japanese and Caucasian voxel models. In addition, for radiation protection of the environment, AFs have been evaluated using a frog voxel model. Each study was performed by using Monte Carlo simulations. Consequently, it was concluded that these data of Monte Carlo simulations and voxel models could adequately reproduce measurement results. Voxel models were found to be a significant tool for internal dosimetry since the models are anatomically realistic. This fact indicates that several studies on correction of the in vivo measurement efficiency for the variability of human subjects and interspecies scaling of organ doses will succeed.

  17. Computerized MRS voxel registration and partial volume effects in single voxel 1H-MRS.

    Science.gov (United States)

    Lee, Hedok; Caparelli, Elisabeth; Li, Haifang; Mandal, Amit; Smith, S David; Zhang, Shaonan; Bilfinger, Thomas V; Benveniste, Helene

    2013-09-01

    Partial volume effects in proton magnetic resonance spectroscopy in the brain have been studied previously in terms of proper water concentration calculations, but there is a lack of disclosure in terms of voxel placement techniques that would affect the calculations. The purpose of this study is to facilitate a fully automated MRS voxel registration method which is time efficient, accurate, and can be extended to all imaging modalities. A total of thirteen healthy adults underwent single voxel 1H-MRS scans in 3.0T MRI scanners. Transposition of a MRS voxel onto an anatomical scan is derived along with a full calculation of water concentration with a correction term to account for the partial volume effects. Five metabolites (tNAA, Glx, tCr, mI, and tCho) known to yield high reliability are studied. Pearson's correlation analyses between tissue volume fractions and metabolite concentrations were statistically significant in parietal (tCr, Glx, and tNAA) lobe and occipital lobe (tNAA). MRS voxel overlaps quantified by dice metric over repeated visits yielded 60%~70% and coefficients of variance in metabolites concentration were 4%~10%. These findings reiterate an importance of considering the partial volume effects when tissue water is used as an internal concentration reference so as to avoid misinterpreting a morphometric difference as a metabolic difference.

  18. Size distributions of coastal ocean suspended particulate inorganic matter: Amorphous silica and clay minerals and their dynamics

    Science.gov (United States)

    Zhang, Xiaodong; Stavn, Robert H.; Falster, Alexander U.; Rick, Johannes J.; Gray, Deric; Gould, Richard W.

    2017-04-01

    Particulate inorganic matter (PIM) is a key component in estuarine and coastal systems and plays a critical role in trace metal cycling. Better understanding of coastal dynamics and biogeochemistry requires improved quantification of PIM in terms of its concentration, size distribution, and mineral species composition. The angular pattern of light scattering contains detailed information about the size and composition of particles. These volume scattering functions (VSFs) were measured in Mobile Bay, Alabama, USA, a dynamic, PIM dominated coastal environment. From measured VSFs, we determined through inversion the particle size distributions (PSDs) of major components of PIM, amorphous silica and clay minerals. An innovation here is the extension of our reported PSDs significantly into the submicron range. The PSDs of autochthonous amorphous silica exhibit two unique features: a peak centered at about 0.8 μm between 0.2 and 4 μm and a very broad shoulder essentially extending from 4 μm to >100 μm. With an active and steady particle source from blooming diatoms, the shapes of amorphous silica PSDs for sizes 10 μm inside the bay, likely due to wind-induced resuspension of larger frustules that have settled. Compared to autochthonous amorphous silica, the allochthonous clay minerals are denser and exhibit relatively narrower PSDs with peaks located between 1 and 4 μm. Preferential settling of larger mineral particles as well as the smaller but denser illite component further narrowed the size distributions of clay minerals as they were being transported outside the bay. The derived PSDs also indicated a very dynamic situation in Mobile Bay when a cold weather front passed through during the experiment. With northerly winds of speeds up to 15 m s-1, both amorphous silica and clay minerals showed a dramatic increase in concentration and broadening in size distribution outside the exit of the barrier islands, indicative of wind-induced resuspension and subsequent

  19. Structure Matters More than Size: Tuning the Electronic Properties of (TiO2)n Clusters

    Science.gov (United States)

    Marom, Noa; Bhattacharya, Saswata; Ghiringhelli, Luca

    2015-03-01

    To design (TiO2)n clusters with desired properties we implemented a suite of three genetic algorithms (GA) tailored to optimize for low total energy (EGA), high vertical electron affinity (VEA-GA), and low vertical ionization potential (VIP-GA). The property-based GAs are an extension of the cascade GA reported in. Analysis of the structures found by the VEA-GA and the VIP-GA vs. the EGA reveals structure-property relations. A high VEA is correlated with the presence of several dangling-O atoms (typically 3-4), rather than the previously suggested tri-coordinated Ti atom. A low VIP is correlated with low bond connectivity (typically 2) between two dangling-O atoms. We show that the electronic properties of (TiO2)n clusters with n up to 20 correlate more strongly with the presence of these structural features than with size. We further suggest that the presence of dangling-O atoms on TiO2 clusters or surfaces may be associated with enhanced catalytic activity and that these O atoms may serve as active sites. The process of optimization for a target property reveals the underlying structure-property relations and the structural features that may serve as active sites for catalysis. This generally applicable approach may provide valuable physical insight and design rules for better nanocatalysts.

  20. The size evolution of galaxy discs formed within Lambda Cold Dark Matter haloes

    CERN Document Server

    Firmani, C

    2009-01-01

    By means of galaxy evolutionary models, we explore the direct consequences of the LCDM cosmogony on the size evolution of galactic discs, avoiding intentionally the introduction of intermediate (uncertain) astrophysical processes. Based on the shape of the rotation curves and guided by a simplicity criterion, we adopt an average galaxy mass baryon fraction of 0.03. In order to study general behaviors, only models with the average initial conditions are analyzed. The stellar and B-band effective radii, R* and RB, of individual galaxies grow significantly with time (inside-out disc formation) with laws that are weakly dependent on mass, M*,or luminosity, LB. However, the change of R* with z at fixed M* is slow; for z0.75. We find also that at z=0, R* ~ M*^0.38 and RB ~ LB^0.40, remaining the slopes of these relations almost the same up to z ~ 3. Our predictions are in reasonable agreement with observational inferences on the typical radius change with z of late-type galaxies more luminous (massive) than high va...

  1. Fathers matter: male body mass affects life-history traits in a size-dimorphic seabird.

    Science.gov (United States)

    Cornioley, Tina; Jenouvrier, Stéphanie; Börger, Luca; Weimerskirch, Henri; Ozgul, Arpat

    2017-05-17

    One of the predicted consequences of climate change is a shift in body mass distributions within animal populations. Yet body mass, an important component of the physiological state of an organism, can affect key life-history traits and consequently population dynamics. Over the past decades, the wandering albatross-a pelagic seabird providing bi-parental care with marked sexual size dimorphism-has exhibited an increase in average body mass and breeding success in parallel with experiencing increasing wind speeds. To assess the impact of these changes, we examined how body mass affects five key life-history traits at the individual level: adult survival, breeding probability, breeding success, chick mass and juvenile survival. We found that male mass impacted all traits examined except breeding probability, whereas female mass affected none. Adult male survival increased with increasing mass. Increasing adult male mass increased breeding success and mass of sons but not of daughters. Juvenile male survival increased with their chick mass. These results suggest that a higher investment in sons by fathers can increase their inclusive fitness, which is not the case for daughters. Our study highlights sex-specific differences in the effect of body mass on the life history of a monogamous species with bi-parental care. © 2017 The Authors.

  2. Single Voxel Proton Spectroscopy for Neurofeedback at 7 Tesla.

    Science.gov (United States)

    Koush, Yury; Elliott, Mark A; Mathiak, Klaus

    2011-09-01

    Echo-planar imaging (EPI) in fMRI is regularly used to reveal BOLD activation in presubscribed regions of interest (ROI). The response is mediated by relative changes in T2* which appear as changes in the image pixel intensities. We have proposed an application of functional single-voxel proton spectroscopy (fSVPS) for real-time studies at ultra-high MR field which can be comparable to the EPI BOLD fMRI technique. A spin-echo SVPS protocol without water suppression was acquired with 310 repetitions on a 7T Siemens MR scanner (TE/TR = 20/1000 ms, flip angle α = 90°, voxel size 10 × 10 × 10 mm(3)). Transmitter reference voltage was optimized for the voxel location. Spectral processing of the water signal free induction decay (FID) using log-linear regression was used to estimate the T2* change between rest and activation of a functional task. The FID spectrum was filtered with a Gaussian window around the water peak, and log-linear regression was optimized for the particular ROI by adoption of the linearization length. The spectroscopic voxel was positioned on an ROI defined from a real-time fMRI EPI BOLD localizer. Additional online signal processing algorithms performed signal drift removal (exponential moving average), despiking and low-pass filtering (modified Kalman filter) and, finally, the dynamic feedback signal normalization. Two functional tasks were used to estimate the sensitivity of the SVPS method compared to BOLD signal changes, namely the primary motor cortex (PMC, left hand finger tapping) and visual cortex (VC, blinking checkerboard). Four healthy volunteers performed these tasks and an additional session using real-time signal feedback modulating their activation level of the PMC. Results show that single voxel spectroscopy is able to provide a good and reliable estimation of the BOLD signal changes. Small data size and FID signal processing instead of processing entire brain volumes as well as more information revealed from the acquired total

  3. Single Voxel Proton Spectroscopy for Neurofeedback at 7 Tesla

    Directory of Open Access Journals (Sweden)

    Mark A. Elliott

    2011-09-01

    Full Text Available Echo-planar imaging (EPI in fMRI is regularly used to reveal BOLD activation in presubscribed regions of interest (ROI. The response is mediated by relative changes in T2* which appear as changes in the image pixel intensities. We have proposed an application of functional single-voxel proton spectroscopy (fSVPS for real-time studies at ultra-high MR field which can be comparable to the EPI BOLD fMRI technique. A spin-echo SVPS protocol without water suppression was acquired with 310 repetitions on a 7T Siemens MR scanner (TE/TR = 20/1000 ms, flip angle α = 90°, voxel size 10 × 10 × 10 mm3. Transmitter reference voltage was optimized for the voxel location. Spectral processing of the water signal free induction decay (FID using log-linear regression was used to estimate the T2* change between rest and activation of a functional task. The FID spectrum was filtered with a Gaussian window around the water peak, and log-linear regression was optimized for the particular ROI by adoption of the linearization length. The spectroscopic voxel was positioned on an ROI defined from a real-time fMRI EPI BOLD localizer. Additional online signal processing algorithms performed signal drift removal (exponential moving average, despiking and low-pass filtering (modified Kalman filter and, finally, the dynamic feedback signal normalization. Two functional tasks were used to estimate the sensitivity of the SVPS method compared to BOLD signal changes, namely the primary motor cortex (PMC, left hand finger tapping and visual cortex (VC, blinking checkerboard. Four healthy volunteers performed these tasks and an additional session using real-time signal feedback modulating their activation level of the PMC. Results show that single voxel spectroscopy is able to provide a good and reliable estimation of the BOLD signal changes. Small data size and FID signal processing instead of processing entire brain volumes as well as more information revealed from the

  4. A combined VBM and DTI study of schizophrenia: bilateral decreased insula volume and cerebral white matter disintegrity corresponding to subinsular white matter projections unlinked to clinical symptomatology.

    Science.gov (United States)

    Onay, Aslıhan; Yapıcı Eser, Hale; Ulaşoğlu Yıldız, Çiğdem; Aslan, Selçuk; Talı, Erhan Turgut

    2017-01-01

    Grey matter and white matter changes within the brain are well defined in schizophrenia. However, most studies focused on either grey matter changes or white matter integrity separately; only in limited number of studies these changes were interpreted in the same frame. In addition, the relationship of these findings with clinical variables is not clearly established. Here, we aimed to investigate the grey matter and white matter changes in schizophrenia patients and exhibit the relation of these imaging findings with clinical variables. A total of 20 schizophrenia patients and 16 matched healthy controls underwent magnetic resonance imaging to investigate the grey matter and white matter alterations that occur in schizophrenia patients using voxel-based morphometry (VBM) and whole brain voxel-wise analysis of diffusion tensor imaging (DTI) parameters with SPM8, respectively. While the preprocessing steps of VBM were performed with the default parameters of VBM8 toolbox, the preprocessing steps of DTI were carried out using FSL. Additionally, VBM results were correlated with clinical variables. Bilateral insula showed decreased grey matter volume in schizophrenia patients compared with healthy controls (P < 0.01). The opposite contrast did not show a significant difference. Psychiatric scores, duration of illness, and age were not correlated with the decreased grey matter volume of insula in schizophrenia patients. DTI analysis revealed a significant increase in mean, radial, and axial diffusivity, mainly of the fibers of bilateral anterior thalamic radiation and superior longitudinal fasciculus with left predominance, which intersected with bilateral subinsular white matter (P < 0.05). Our findings suggest that insula may be the main affected brain region in schizophrenia, which is also well supported by the literature. Our results were independent of disease duration and schizophrenia symptoms. White matter alterations were observed within bilateral anterior

  5. The structure of the amygdala associates with human sexual permissiveness: evidence from voxel-based morphometry.

    Science.gov (United States)

    Takeuchi, Hikaru; Taki, Yasuyuki; Nouchi, Rui; Hashizume, Hiroshi; Sekiguchi, Atsushi; Kotozaki, Yuka; Nakagawa, Seishu; Miyauchi, Carlos Makoto; Sassa, Yuko; Kawashima, Ryuta

    2015-02-01

    Sexual behavior is a critical function of human procreation. Despite previous studies that investigated the neural mechanisms of basic human physiological sexual functions, the neural mechanisms that underlie individual differences in human sexual permissiveness remain unknown. We used voxel-based morphometry and a questionnaire (scale for sexual attitudes) to measure sexual permissiveness to investigate the gray matter and white matter structural correlates of sexual permissiveness. Sexual permissiveness was negatively correlated with regional gray matter density of the structures involving the right amygdala and surrounding areas, and positively correlated with regional white matter density of the white matter area that spread around the left amygdala to the hypothalamus area. There were no gender-specific relationships in the neural correlates of our findings. These findings suggest that structural variations in regions that play key roles in the basic physiological aspects of human sexuality underlie individual complex sexual attitudes in social life. © 2014 The Authors. Human Brain Mapping Published by Wiley Periodicals, Inc.

  6. Failure of implantable cardioverter-defibrillator leads: a matter of lead size?

    Science.gov (United States)

    Rordorf, Roberto; Poggio, Luca; Savastano, Simone; Vicentini, Alessandro; Petracci, Barbara; Chieffo, Enrico; Klersy, Catherine; Landolina, Maurizio

    2013-02-01

    Small-diameter implantable cardioverter-defibrillator (ICD) Sprint Fidelis and Riata leads have been recalled owing to an increased risk of lead failure, thus arousing the suspicion that lead size might be a critical issue. To compare the incidence of failure of small-diameter (≤8 F) and standard-diameter (>8 F) ICD leads implanted in a single center. From January 2003 to December 2010, 190 Sprint Fidelis, 182 Riata/Riata ST, 99 Optim (Riata Optim/Durata), and 419 standard-diameter leads were implanted in our center. During a median follow-up of 33 months, the overall failure rate was 6.3%. Follow-up duration was similar for Sprint Fidelis, Riata, and standard-diameter leads but shorter for the Optim group. The failure rate was significantly higher in Sprint Fidelis leads than in both standard-diameter (4.8%/year vs 0.8%/year; P<.001) and Riata/Riata ST (4.8%/year vs 2.6%/year; P = .03) leads. The incidence of lead failure in Riata/Riata ST leads proved significantly higher than in standard-diameter leads (2.6%/year vs 0.8%/year; P = .001). No cases of lead failure were recorded in the Optim group. On multivariable analyses, small-diameter (hazard ratio [HR] 5.03, 2.53-10.01, P<.001), Sprint Fidelis (HR 6.3, 3.1-13.3, P<.001), or Riata/Riata ST (HR 4.5, 1.9-10.5, P = .001) leads and age<60 years (HR 2.3, 1.3-4.3, P = .005) were found to independently increase the risk of lead failure. Compared with standard-diameter leads, both Sprint Fidelis and Riata/Riata ST small-diameter ICD leads are at an increased risk of failure, although the incidence of events is significantly lower in the Riata than in the Sprint Fidelis group. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  7. Organic composition of size segregated atmospheric particulate matter, during summer and winter sampling campaigns at representative sites in Madrid, Spain

    Science.gov (United States)

    Mirante, Fátima; Alves, Célia; Pio, Casimiro; Pindado, Oscar; Perez, Rosa; Revuelta, M.a. Aranzazu; Artiñano, Begoña

    2013-10-01

    Madrid, the largest city of Spain, has some and unique air pollution problems, such as emissions from residential coal burning, a huge vehicle fleet and frequent African dust outbreaks, along with the lack of industrial emissions. The chemical composition of particulate matter (PM) was studied during summer and winter sampling campaigns, conducted in order to obtain size-segregated information at two different urban sites (roadside and urban background). PM was sampled with high volume cascade impactors, with 4 stages: 10-2.5, 2.5-1, 1-0.5 and extracted and organic compounds were identified and quantified by GC-MS. Alkanes, polycyclic aromatic hydrocarbons (PAHs), alcohols and fatty acids were chromatographically resolved. The PM1-2.5 was the fraction with the highest mass percentage of organics. Acids were the organic compounds that dominated all particle size fractions. Different organic compounds presented apparently different seasonal characteristics, reflecting distinct emission sources, such as vehicle exhausts and biogenic sources. The benzo[a]pyrene equivalent concentrations were lower than 1 ng m- 3. The estimated carcinogenic risk is low.

  8. Multisensor on-the-go mapping of readily dispersible clay, particle size and soil organic matter

    Science.gov (United States)

    Debaene, Guillaume; Niedźwiecki, Jacek; Papierowska, Ewa

    2016-04-01

    Particle size fractions affect strongly the physical and chemical properties of soil. Readily dispersible clay (RDC) is the part of the clay fraction in soils that is easily or potentially dispersible in water when small amounts of mechanical energy are applied to soil. The amount of RDC in the soil is of significant importance for agriculture and environment because clay dispersion is a cause of poor soil stability in water which in turn contributes to soil erodibility, mud flows, and cementation. To obtain a detailed map of soil texture, many samples are needed. Moreover, RDC determination is time consuming. The use of a mobile visible and near-infrared (VIS-NIR) platform is proposed here to map those soil properties and obtain the first detailed map of RDC at field level. Soil properties prediction was based on calibration model developed with 10 representative samples selected by a fuzzy logic algorithm. Calibration samples were analysed for soil texture (clay, silt and sand), RDC and soil organic carbon (SOC) using conventional wet chemistry analysis. Moreover, the Veris mobile sensor platform is also collecting electrical conductivity (EC) data (deep and shallow), and soil temperature. These auxiliary data were combined with VIS-NIR measurement (data fusion) to improve prediction results. EC maps were also produced to help understanding RDC data. The resulting maps were visually compared with an orthophotography of the field taken at the beginning of the plant growing season. Models were developed with partial least square regression (PLSR) and support vector machine regression (SVMR). There were no significant differences between calibration using PLSR or SVMR. Nevertheless, the best models were obtained with PLSR and standard normal variate (SNV) pretreatment and the fusion with deep EC data (e.g. for RDC and clay content: RMSECV = 0,35% and R2 = 0,71; RMSECV = 0,32% and R2 = 0,73 respectively). The best models were used to predict soil properties from the

  9. Impact of cow size on dry matter intake, residual feed intake, metabolic response, and cow performance.

    Science.gov (United States)

    Walker, R S; Martin, R M; Gentry, G T; Gentry, L R

    2015-02-01

    Thirty-eight Angus-cross beef cows were used to evaluate differences in DMI, residual feed intake (RFI), and endocrine markers on the basis of cow size and RFI ranking during 2 stages of production. Cows housed in individual pens (2.2 × 9.1 m) were fed, over a 70-d feeding period, 30% Bermuda grass hay and 70% ryegrass baleage diet during lactation (LACT) and a 100% ryegrass hay diet during postweaning (NOLACT). Individual daily feed intake, BW, and BCS were recorded, and hip height was used to determine frame score (FS). Feed intake was used to calculate RFI for each cow, and cow was the experimental unit. Blood samples were obtained on d 0 and 70 and were analyzed for glucose, insulin, leptin, triiodothyronine (T3), and thyroxine (T4). Cows were assigned to a light (LIT) or heavy (HEV) BW groups on the basis of mean BW at the beginning of the LACT period. On the basis of RFI values for each feeding period, cows were placed into a negative (NEG; RFI 0.00) RFI group and into a low (LOW; ≤0.2 SD mean RFI), medium (MED; within ±0.19 SD), or high (HI; ≥0.2 SD mean RFI) RFI group. During LACT, DMI was 4.8% greater (P = 0.03) and FS was greater (P 0.05) among BW groups; however, DMI was 6.5% and 8.9% greater (P < 0.01) for POS compared with NEG RFI in the LACT and NOLACT periods. In LACT, DMI was greater (P < 0.01) for HI and MED RFI compared with LOW RFI, and in NOLACT, DMI was greater (P < 0.01) for the HI compared with MED and LOW RFI cows and MED compared with LOW RFI cows. During NOLACT, DMI was 8.9% greater (P < 0.01) for the HEV (12.4 ± 0.22 kg) compared with LIT (11.3 ± 0.19 kg) BW cows. Change in BCS was greater (P ≤ 0.03) in higher RFI cows in both RFI groups only in the NOLACT period. Differences in T3 and T4 on d 0 and 70 were 25% and 15% greater (P ≤ 0.04) for the LIT BW group compared with the HEV BW group. A negative correlation existed (P ≤ 0.04) between BW group and T3 and T4, as well as leptin and RFI (P = 0.03). Although cow BW was

  10. Characterisation of the organic composition of size segregated atmospheric particulate matter at traffic exposed and background sites in Madrid

    Science.gov (United States)

    Mirante, F.; Perez, R.; Alves, C.; Revuelta, M.; Pio, C.; Artiñano, B.; Nunes, T.

    2010-05-01

    The growing awareness of the impact of atmospheric particulate matter (PM) on climate, and the incompletely recognised but serious effects of anthropogenic aerosols on air quality and human health, have led to diverse studies involving almost exclusively the coarse or the fine PM fractions. However, these environmental effects, the PM formation processes and the source assignment depend greatly on the particle size distribution. The innovative character of this study consists in obtaining time series with a size-segregated detailed chemical composition of PM for differently polluted sites. In this perspective, a summer sampling campaign was carried out from 1 of June to 1 of July 2009. One of the sampling sites was located at a representative urban monitoring station (Escuelas Aguirre) belonging to the municipal network, located at a heavy traffic street intersection in downtown Madrid. Other sampling point was positioned within the CIEMAT area, located in the NW corner of the city, which can be considered an urban background or suburban site. Particulate matter was sampled with high volume cascade impactors at 4 size stages: 10-2.5, 2.5-0.95, 0.95-0.45 and < 0.45 µm. Daily sampling was carried out on quartz fibre filters. Based on meteorological conditions and PM mass concentrations, each one of the 7 groups of filters collected during the first week were combined with the corresponding filters of the third week. The same procedure was undertaken with samples of the second and fourth weeks. Filters of 0.95-0.45 and < 0.45 µm were pooled to obtain the PM0.95 organic composition. The PM size-segregated samples were subjected to organic analysis by gas chromatography-mass spectrometry (GC-MS), after solvent extraction of filters and an appropriate derivatisation technique. Besides the homologous compound series of organic classes (e.g. n-alkanes, n-alkanols and n-alkanoic acids), special attention was given to the determination of specific molecular markers for

  11. Comparative toxicity of size-fractionated airborne particulate matter obtained from different cities in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Gilmour, M.I.; McGee, J.; Duvall, R.M.; Dailey, L.; Daniels, M.; Boykin, E.; Cho, S.H.; Doerfler, D.; Gordon, T.; Devlin, R.B. [US EPA, Research Triangle Park, NC (United States)

    2007-07-01

    Hundreds of epidemiological studies have shown that exposure to ambient particulate matter (PM) is associated with dose-dependent increases in morbidity and mortality. While early reports focused on PM less than 10 {mu}m (PM10), numerous studies have since shown that the effects can occur with PM stratified into ultrafine (UF), fine (FI), and coarse (CO) size modes despite the fact that these materials differ significantly in both evolution and chemistry. Furthermore the chemical makeup of these different size fractions can vary tremendously depending on location, meteorology, and source profile. For this reason, high-volume three-stage particle impactors with the capacity to collect UF, FI, and CO particles were deployed to four different locations in the United States (Seattle, WA; Salt Lake City, UT; Sterling Forest and South Bronx, NY), and weekly samples were collected for 1 mo in each place. The particles were extracted, assayed for a standardized battery of chemical components, and instilled into mouse lungs (female BALB/c) at doses of 25 and 100 {mu}g. Eighteen hours later animals were euthanized and parameters of injury and inflammation were monitored in the bronchoalveolar lavage fluid and plasma. Of the four locations, the South Bronx coarse fraction was the most potent sample in both pulmonary and systemic biomarkers. Receptor source modeling on the PM2.5 samples showed that the South Bronx sample was heavily influenced by emissions from coal fired power plants (31%) and mobile sources (22%). Further studies will assess how source profiles correlate with the observed effects for all locations and size fractions.

  12. Short-term bioavailability of carbon in soil organic matter fractions of different particle sizes and densities in grassland ecosystems.

    Science.gov (United States)

    Breulmann, Marc; Masyutenko, Nina Petrovna; Kogut, Boris Maratovich; Schroll, Reiner; Dörfler, Ulrike; Buscot, François; Schulz, Elke

    2014-11-01

    The quality, stability and availability of organic carbon (OC) in soil organic matter (SOM) can vary widely between differently managed ecosystems. Several approaches have been developed for isolating SOM fractions to examine their ecological roles, but links between the bioavailability of the OC of size-density fractions and soil microbial communities have not been previously explored. Thus, in the presented laboratory study we investigated the potential bioavailability of OC and the structure of associated microbial communities in different particle-size and density fractions of SOM. For this we used samples from four grassland ecosystems with contrasting management intensity regimes and two soil types: a Haplic Cambisol and a typical Chernozem. A combined size-density fractionation protocol was applied to separate clay-associated SOM fractions (CF1, fractions (LF1, fractions were used as carbon sources in a respiration experiment to determine their potential bioavailability. Measured CO2-release was used as an index of substrate accessibility and linked to the soil microbial community structure, as determined by phospholipid fatty acids (PLFA) analysis. Several key factors controlling decomposition processes, and thus the potential bioavailability of OC, were identified: management intensity and the plant community composition of the grasslands (both of which affect the chemical composition and turnover of OC) and specific properties of individual SOM fractions. The PLFA patterns highlighted differences in the composition of microbial communities associated with the examined grasslands, and SOM fractions, providing the first broad insights into their active microbial communities. From observed interactions between abiotic and biotic factors affecting the decomposition of SOM fractions we demonstrate that increasing management intensity could enhance the potential bioavailability of OC, not only in the active and intermediate SOM pools, but also in the passive

  13. New hybrid voxelized/analytical primitive in Monte Carlo simulations for medical applications

    Science.gov (United States)

    Bert, Julien; Lemaréchal, Yannick; Visvikis, Dimitris

    2016-05-01

    Monte Carlo simulations (MCS) applied in particle physics play a key role in medical imaging and particle therapy. In such simulations, particles are transported through voxelized phantoms derived from predominantly patient CT images. However, such voxelized object representation limits the incorporation of fine elements, such as artificial implants from CAD modeling or anatomical and functional details extracted from other imaging modalities. In this work we propose a new hYbrid Voxelized/ANalytical primitive (YVAN) that combines both voxelized and analytical object descriptions within the same MCS, without the need to simultaneously run two parallel simulations, which is the current gold standard methodology. Given that YVAN is simply a new primitive object, it does not require any modifications on the underlying MC navigation code. The new proposed primitive was assessed through a first simple MCS. Results from the YVAN primitive were compared against an MCS using a pure analytical geometry and the layer mass geometry concept. A perfect agreement was found between these simulations, leading to the conclusion that the new hybrid primitive is able to accurately and efficiently handle phantoms defined by a mixture of voxelized and analytical objects. In addition, two application-based evaluation studies in coronary angiography and intra-operative radiotherapy showed that the use of YVAN was 6.5% and 12.2% faster than the layered mass geometry method, respectively, without any associated loss of accuracy. However, the simplification advantages and differences in computational time improvements obtained with YVAN depend on the relative proportion of the analytical and voxelized structures used in the simulation as well as the size and number of triangles used in the description of the analytical object meshes.

  14. New hybrid voxelized/analytical primitive in Monte Carlo simulations for medical applications.

    Science.gov (United States)

    Bert, Julien; Lemaréchal, Yannick; Visvikis, Dimitris

    2016-05-01

    Monte Carlo simulations (MCS) applied in particle physics play a key role in medical imaging and particle therapy. In such simulations, particles are transported through voxelized phantoms derived from predominantly patient CT images. However, such voxelized object representation limits the incorporation of fine elements, such as artificial implants from CAD modeling or anatomical and functional details extracted from other imaging modalities. In this work we propose a new hYbrid Voxelized/ANalytical primitive (YVAN) that combines both voxelized and analytical object descriptions within the same MCS, without the need to simultaneously run two parallel simulations, which is the current gold standard methodology. Given that YVAN is simply a new primitive object, it does not require any modifications on the underlying MC navigation code. The new proposed primitive was assessed through a first simple MCS. Results from the YVAN primitive were compared against an MCS using a pure analytical geometry and the layer mass geometry concept. A perfect agreement was found between these simulations, leading to the conclusion that the new hybrid primitive is able to accurately and efficiently handle phantoms defined by a mixture of voxelized and analytical objects. In addition, two application-based evaluation studies in coronary angiography and intra-operative radiotherapy showed that the use of YVAN was 6.5% and 12.2% faster than the layered mass geometry method, respectively, without any associated loss of accuracy. However, the simplification advantages and differences in computational time improvements obtained with YVAN depend on the relative proportion of the analytical and voxelized structures used in the simulation as well as the size and number of triangles used in the description of the analytical object meshes.

  15. Voxel-based morphometry and automated lobar volumetry: the trade-off between spatial scale and statistical correction.

    Science.gov (United States)

    Voormolen, Eduard H J; Wei, Corie; Chow, Eva W C; Bassett, Anne S; Mikulis, David J; Crawley, Adrian P

    2010-01-01

    Voxel-based morphometry (VBM) and automated lobar region of interest (ROI) volumetry are comprehensive and fast methods to detect differences in overall brain anatomy on magnetic resonance images. However, VBM and automated lobar ROI volumetry have detected dissimilar gray matter differences within identical image sets in our own experience and in previous reports. To gain more insight into how diverging results arise and to attempt to establish whether one method is superior to the other, we investigated how differences in spatial scale and in the need to statistically correct for multiple spatial comparisons influence the relative sensitivity of either technique to group differences in gray matter volumes. We assessed the performance of both techniques on a small dataset containing simulated gray matter deficits and additionally on a dataset of 22q11-deletion syndrome patients with schizophrenia (22q11DS-SZ) vs. matched controls. VBM was more sensitive to simulated focal deficits compared to automated ROI volumetry, and could detect global cortical deficits equally well. Moreover, theoretical calculations of VBM and ROI detection sensitivities to focal deficits showed that at increasing ROI size, ROI volumetry suffers more from loss in sensitivity than VBM. Furthermore, VBM and automated ROI found corresponding GM deficits in 22q11DS-SZ patients, except in the parietal lobe. Here, automated lobar ROI volumetry found a significant deficit only after a smaller sub-region of interest was employed. Thus, sensitivity to focal differences is impaired relatively more by averaging over larger volumes in automated ROI methods than by the correction for multiple comparisons in VBM. These findings indicate that VBM is to be preferred over automated lobar-scale ROI volumetry for assessing gray matter volume differences between groups.

  16. Size distribution of alkyl amines in continental particulate matter and their online detection in the gas and particle phase

    Directory of Open Access Journals (Sweden)

    T. C. VandenBoer

    2011-05-01

    Full Text Available An ion chromatographic method is described for the quantification of the simple alkyl amines: methylamine (MA, dimethylamine (DMA, trimethylamine (TMA, ethylamine (EA, diethylamine (DEA and triethylamine (TEA, in the ambient atmosphere. Limits of detection (3σ are in the tens of pmol range for all of these amines, and good resolution is achieved for all compounds except for TMA and DEA. The technique was applied to the analysis of time-integrated samples collected using a micro-orifice uniform deposition impactor (MOUDI with ten stages for size resolution of particles with aerodynamic diameters between 56 nm and 18 μm. In eight samples from urban and rural continental airmasses, the mass loading of amines consistently maximized on the stage corresponding to particles with aerodynamic diameters between 320 and 560 nm. The molar ratio of amines to ammonium (R3NH+/NH4+ in fine aerosol ranged between 0.005 and 0.2, and maximized for the smallest particle sizes. The size-dependence of the R3NH+/NH4+ ratio indicates differences in the relative importance of the processes leading to the incorporation of amines and ammonia into secondary particles. The technique was also used to make simultaneous hourly online measurements of amines in the gas phase and in fine particulate matter using an Ambient Ion Monitor Ion Chromatograph (AIM-IC. During a ten day campaign in downtown Toronto, DMA, TMA + DEA, and TEA were observed to range from below detection limit to 2.7 ppt in the gas phase. In the particle phase, MAH+ and TMAH+ + DEAH+ were observed to range from below detection limit up to 15 ng m−3. The presence of detectable levels of amines in the particle phase corresponded to periods with higher relative humidity and higher mass loadings of nitrate. While the hourly measurements made using the AIM-IC provide data that can

  17. Size distribution of alkyl amines in continental particulate matter and their online detection in the gas and particle phase

    Directory of Open Access Journals (Sweden)

    T. C. VandenBoer

    2010-11-01

    Full Text Available An ion chromatographic method is described for the quantification of the simple alkyl amines: methylamine (MA, dimethylamine (DMA, trimethylamine (TMA, ethylamine (EA, diethylamine (DEA and triethylamine (TEA, in the ambient atmosphere. Limits of detection (3σ are in the tens of pmol range for all of these amines, and good resolution is achieved for all compounds except for TMA and DEA. The technique was applied to the analysis of time-integrated samples collected using a micro-orifice uniform deposition impactor (MOUDI with ten stages for size resolution of particles with aerodynamic diameters between 56 nm and 18 μm. In eight samples from urban and rural continental airmasses, the mass loading of amines consistently maximized on the stage corresponding to particles with aerodynamic diameters between 320 and 560 nm. The molar ratio of amines to ammonium (R3NH+/NH4+ in fine aerosol ranged between 0.005 and 0.2, and maximized for the smallest particle sizes. The size-dependence of the R3NH+/NH4+ ratio indicates differences in the relative importance of the processes leading to the incorporation of amines and ammonia into secondary particles. The technique was also used to make simultaneous hourly online measurements of amines in the gas phase and in fine particulate matter using an Ambient Ion Monitor Ion Chromatograph (AIM-IC. During a ten day campaign in downtown Toronto, DMA, TMA+DEA, and TEA were observed to range from below detection limit to 2.7 ppt in the gas phase. In the particle phase, MAH+ and TMAH++DEAH+ were observed to range from below detection limit up to 15 ng m−3. The presence of detectable levels of amines in the particle phase corresponded to periods with higher relative humidity and higher mass loadings of nitrate. While the hourly measurements made using the AIM-IC provide data that can be

  18. Size distribution of alkyl amines in continental particulate matter and their online detection in the gas and particle phase

    Science.gov (United States)

    Vandenboer, T. C.; Petroff, A.; Markovic, M. Z.; Murphy, J. G.

    2011-05-01

    An ion chromatographic method is described for the quantification of the simple alkyl amines: methylamine (MA), dimethylamine (DMA), trimethylamine (TMA), ethylamine (EA), diethylamine (DEA) and triethylamine (TEA), in the ambient atmosphere. Limits of detection (3σ) are in the tens of pmol range for all of these amines, and good resolution is achieved for all compounds except for TMA and DEA. The technique was applied to the analysis of time-integrated samples collected using a micro-orifice uniform deposition impactor (MOUDI) with ten stages for size resolution of particles with aerodynamic diameters between 56 nm and 18 μm. In eight samples from urban and rural continental airmasses, the mass loading of amines consistently maximized on the stage corresponding to particles with aerodynamic diameters between 320 and 560 nm. The molar ratio of amines to ammonium (R3NH+/NH4+) in fine aerosol ranged between 0.005 and 0.2, and maximized for the smallest particle sizes. The size-dependence of the R3NH+/NH4+ ratio indicates differences in the relative importance of the processes leading to the incorporation of amines and ammonia into secondary particles. The technique was also used to make simultaneous hourly online measurements of amines in the gas phase and in fine particulate matter using an Ambient Ion Monitor Ion Chromatograph (AIM-IC). During a ten day campaign in downtown Toronto, DMA, TMA + DEA, and TEA were observed to range from below detection limit to 2.7 ppt in the gas phase. In the particle phase, MAH+ and TMAH+ + DEAH+ were observed to range from below detection limit up to 15 ng m-3. The presence of detectable levels of amines in the particle phase corresponded to periods with higher relative humidity and higher mass loadings of nitrate. While the hourly measurements made using the AIM-IC provide data that can be used to evaluate the application of gas-particle partitioning models to amines, the strong size-dependence of the R3NH+/NH4+ ratio indicates

  19. Does market size matter?

    OpenAIRE

    Harry Bloch; B. Curtis Eaton; R. Rothschild

    2013-01-01

    In their efforts to create a position in a market, and to maintain that position, firms make positioning investments of various sorts, in R&D, plant, advertising, and location, or more generally, in product development and maintenance. The heart of this paper is the hypothesis that the success of these positioning investments is not assured. In an environment where the success of positioning investments is stochastic, the positioning game played by firms that compete to serve a market is nece...

  20. When size matters

    DEFF Research Database (Denmark)

    Toft-Bertelsen, Trine L.; Križaj, David; MacAulay, Nanna

    2017-01-01

    Key points: Mammalian cells are frequently exposed to stressors causing volume changes. The transient receptor potential vanilloid 4 (TRPV4) channel translates osmotic stress into ion flux. The molecular mechanism coupling osmolarity to TRPV4 activation remains elusive. TRPV4 responds to isosmola...

  1. Does Size Matter?

    Science.gov (United States)

    Watson, David

    2014-01-01

    In this article, David Watson debates the pros and cons of leadership skills in both a small and large university. Watson relates his own experiences regarding the changing atmosphere of leadership. He states that his experiences have caused him to reflect on what is genuinely generic about individual capacities for institutional leadership: that…

  2. Size does Matter

    Science.gov (United States)

    Vespignani, Alessandro

    From schools of fish and flocks of birds, to digital networks and self-organizing biopolymers, our understanding of spontaneously emergent phenomena, self-organization, and critical behavior is in large part due to complex systems science. The complex systems approach is indeed a very powerful conceptual framework to shed light on the link between the microscopic dynamical evolution of the basic elements of the system and the emergence of oscopic phenomena; often providing evidence for mathematical principles that go beyond the particulars of the individual system, thus hinting to general modeling principles. By killing the myth of the ant queen and shifting the focus on the dynamical interaction across the elements of the systems, complex systems science has ushered our way into the conceptual understanding of many phenomena at the core of major scientific and social challenges such as the emergence of consensus, social opinion dynamics, conflicts and cooperation, contagion phenomena. For many years though, these complex systems approaches to real-world problems were often suffering from being oversimplified and not grounded on actual data...

  3. Size does matter

    CERN Multimedia

    Hollander, Jason

    2009-01-01

    For some kids, age 10 is when they start to memorize players on their favorite baseball team or grow obsessed with a certain cartoon or video game. For David W. Hogg, 10 is when he first became aware that "We live on an absolutely, microscopically insignifiant fleck of dust in the middle of nowhere in this ginormous universe." It might sound like the setup for a Woody Allen protagonist, but the realization cast a lingering spell on him. No one - not his parents, teachers, or friends - could provide relief from the utter fear brought on by it. Out of necessity, young Hogg finally settled on a creed: "The facts is, we are completely insignificant. Suck it up."

  4. Alteration of the molecular-size-distribution of Boom Clay dissolved organic matter induced by Na+ and Ca2 +

    Science.gov (United States)

    Durce, D.; Maes, N.; Bruggeman, C.; Van Ravestyn, L.

    2016-02-01

    In porous media, the extent of dissolved organic matter (DOM)-facilitated contaminant transport depends on the concentration, conformation and the size of the dissolved organic species. Yet, these parameters are highly sensitive to the ionic strength (IS) and the ionic composition of the solution. Boom Clay (BC) which is considered in Belgium as a potential host rock for nuclear waste disposal contains polydisperse DOM that might associate with radionuclide and increase their mobility. To get more insight into the effect of IS on DOM structure and into its impact on the solid/solution partitioning of OM in BC is essential for safety assessment. In a first set, we investigated the influence of NaCl and CaCl2 content on the concentration, the MW distribution and UV spectral parameters of DOM collected from BC. With an increase in IS two main mechanisms were identified: a compaction and/or dissociation of the DOM molecules and an aggregation. We showed that the sensitivity of the DOM species to these two mechanisms was size/MW dependent and that the presence of Ca2 + promotes the aggregation. The largest species are more prone to aggregation which at the extreme leads to their transfer to particulate OM. On the contrary, small DOM species hardly aggregate but compact or dissociate with an increase of IS. These observations were confirmed in the second experimental set in which we followed the release of DOM from BC rock in various electrolytes. The increase of IS and multivalent cations content reduces the amount, the degree of aromaticity and the MW of DOM released from BC which limit the extent of DOM-facilitated contaminant transport in BC.

  5. Associations between personal, indoor, and residential outdoor pollutant concentrations: implications for exposure assessment to size-fractionated particulate matter.

    Science.gov (United States)

    Arhami, Mohammad; Polidori, Andrea; Delfino, Ralph J; Tjoa, Thomas; Sioutas, Constantinos

    2009-04-01

    The physical and chemical characteristics of indoor, outdoor, and personal quasi-ultrafine (matter (PM) levels, their particle components, and gaseous co-pollutants. Seasonal and spatial differences in the concentrations of all measured species were evaluated at all sites on the basis of P values for product terms. Outdoor quasi-ultrafine (UF) and, to a lesser extent, accumulation-mode particles were the two fractions that best correlated with outdoor concentrations of carbon monoxide (CO), nitrogen dioxide (NO2), nitrogen oxides (NOx; during both phases of the study), and ozone (O3; only during the warmer months). Outdoor and indoor concentrations of CO, NO2, and NOx were more positively correlated to personal quasi-UF particles than larger size fractions. Despite these findings, it seems unlikely that these gaseous co-pollutants could confound epidemiologic associations between quasi-UF particles and adverse health effects. Overall, measured gaseous co-pollutants were weak surrogates of personal exposure to accumulation-mode PM, at least for subjects with similar exposure profiles and living in similar urban locations. Indoor sources were not significant contributors to personal exposure of accumulation and quasi-UF PM, which is predominantly influenced by primary emitted pollutants of outdoor origin. Correlations between personal coarse-mode PM and both outdoor and indoor gaseous co-pollutant concentrations were weak at all sites and during all seasons.

  6. Dry matter and digesta particle size gradients along the goat digestive tract on grass and browse diets.

    Science.gov (United States)

    Clauss, M; Fritz, J; Tschuor, A; Braun, U; Hummel, J; Codron, D

    2017-02-01

    Physical properties of the digesta vary along the ruminant digestive tract. They also vary within the forestomach, leading to varying degrees of rumen contents stratification in 'moose-type' (browsing) and 'cattle-type' (intermediate and grazing) ruminants. We investigated the dry matter concentration (DM) and the mean digesta particle size (MPS) within the forestomach and along the digestive tract in 10 goats fed grass hay or dried browse after a standardized 12-h fast, euthanasia and freezing in the natural position. In all animals, irrespective of diet, DM showed a peak in the omasum and an increase from caecum via colon towards the faeces and a decrease in MPS between the reticulum and the omasum. Both patterns are typical for ruminants in general. In the forestomach, there was little systematic difference between more cranial and more caudal locations ('horizontal stratification'), with the possible exception of large particle segregation in the dorsal rumen blindsac on the grass diet. In contrast, the typical (vertical) contents stratification was evident for DM (with drier contents dorsally) and, to a lower degree, for MPS (with larger particles dorsally). Although evident in both groups, this stratification was more pronounced on the grass diet. The results support the interpretation that differences in rumen contents stratification between ruminants are mainly an effect of species-specific physiology, but can be enhanced due to the diet consumed. Journal of Animal Physiology and Animal Nutrition © 2016 Blackwell Verlag GmbH.

  7. Microbial and size characterization of airborne particulate matter collected on sticky tapes along US-Mexico border.

    Science.gov (United States)

    González-Delgado, Amir; Shukla, Manoj K; DuBois, David W; Flores-Márgez, Juan P; Hernández Escamilla, Joel A; Olivas, Evangelina

    2017-03-01

    Particulate matter (PM) emissions from various sources can affect significantly human health and environmental quality especially in the Chihuahuan Desert region along US-Mexico border. The objective of this study was to use the low-cost sticky tape method to collect airborne PM for size characterization and identification of fungal spores. Sticky tape samplers were placed at 1.0 and 2.0m above the ground surface at experimental sites in Ciudad Juárez, Mexico and at 0.6, 1.2 and 1.8m at New Mexico sites, USA. Soil samples were collected in both countries to determine fungal diversity, texture and moisture content. Dust particles collected from all of the experimental sites had a dominant texture of clay (Mexico and US sites. Alternaria, Penicillium and Aspergillus were the three groups of airborne fungal microorganisms consistently present in the US and Mexican sites. The low-cost sticky tape method has the potential to be used for characterizing different airborne microorganisms and dust particles. Copyright © 2016. Published by Elsevier B.V.

  8. The Effect of Composition, Size, and Solubility on Acute Pulmonary Injury in Rats Following Exposure to Mexico City Ambient Particulate Matter Samples

    Science.gov (United States)

    Particulate matter (PM) associated metals contribute to the adverse cardiopulmonary effects following exposure to air pollution. Here, we investigated how variation in the composition and size of ambient PM collected from two distinct regions in Mexico City relates to toxicity d...

  9. Effect of biochar application and soil temperature on characteristics of organic matter associated with aggregate-size and density fractions

    Science.gov (United States)

    Kaiser, Michael; Grunwald, Dennis; Marhan, Sven; Poll, Christian; Bamminger, Chris; Ludwig, Bernard

    2016-04-01

    Potential increases in soil temperature due to climate change might result in intensified soil organic matter (SOM) decomposition and thus higher CO2 emissions. Management options to increase and stabilize SOM include the application of biochar. However, the effects of biochar amendments under elevated soil temperatures on SOM dynamics are largely unknown. The objective of this study was to analyze the effect of biochar application and elevated soil temperature on the amount and composition of OM associated with fractions of different turnover kinetics. Samples were taken from four treatments of the Hohenheim Climate Change Experiment with the factors temperature (ambient or elevated by 2.5 °C in 4 cm depth, six years before sampling) and biochar (control and 30 t / ha Miscanthus pyrolysis biochar, one year before sampling) in two depths (0 - 5 and 5 - 15 cm). Basal respiration and microbial biomass C were analyzed within an incubation experiment. Aggregate size-fractions were separated by wet-sieving and the free light, occluded light (oLF), and heavy fractions were isolated by density fractionation. All fractions were analyzed for organic C and δ13C as well as by infrared spectroscopy. Preliminary data suggest that biochar significantly increased basal respiration and that the microbial biomass C was significantly affected by elevated temperature. No biochar-C was found in the microbial biomass. Biochar and elevated temperature had only minor effects on the organic C associated with aggregate-size classes, although biochar was incorporated into all fractions already after one year of application. Biochar application significantly increased the organic C associated with oLF. In most samples affected by biochar, the proportion of C=O groups was significantly increased. The results suggest that already after one year, biochar-mineral interactions were formed leading to an aggregate occlusion of applied biochar. At least in the short-term, the effect of biochar on

  10. Exploring trees in three dimensions: VoxR, a novel voxel-based R package dedicated to analysing the complex arrangement of tree crowns.

    Science.gov (United States)

    Lecigne, Bastien; Delagrange, Sylvain; Messier, Christian

    2017-09-07

    Interest in tree form assessments using the terrestrial laser scanner (TLS) has increased in recent years. Yet many existing methods are limited to small-sized trees, principally due to noise and occlusion phenomena. In this paper, a novel voxel-based program that is dedicated to the analyses of large tree structures is presented. The method is based on the assumption that architectural trait variations (i.e. branching angle, bifurcation ratio, biomass allocation, etc.) influence the way a tree explores space. This method uses the concept of space exploration that considers a voxel as a portion of space explored by the tree. Once the TLS scene is voxelized, the program provides tools that extract qualitative (geometrical) and quantitative (volumetric) metrics. These tools measure (1) voxel dispersion in three dimensions (3-D), (2) projections of the voxel cloud in 2-D and (3) multi-temporal changes within a single tree crown. To test algorithm capabilities of measuring larger tree architectural traits, two application studies were conducted using point clouds that were either generated by a tree growth simulation model, thereby allowing algorithm application in a perfectly controlled environment, or acquired in the field with a TLS device. The space exploration concept makes it possible to take advantage of the volumetric nature of voxels to compensate for occlusion. The hypothesis that large-sized voxels can be used to reduce occlusion in the original point cloud was tested, as well as the consequences of voxel size on quantification of tree volume and on precision of derived metrics. Results show that space exploration is well adapted to highlight architectural differences among trees. They also suggest that large-sized voxels are efficient for occlusion compensation at the expense of metrics precision in some cases. The best resolution to choose depending on the research objectives and quality of the TLS scan is discussed.

  11. Spatial variations in dietary organic matter sources modulate the size and condition of fish juveniles in temperate lagoon nursery sites

    Science.gov (United States)

    Escalas, Arthur; Ferraton, Franck; Paillon, Christelle; Vidy, Guy; Carcaillet, Frédérique; Salen-Picard, Chantal; Le Loc'h, François; Richard, Pierre; Darnaude, Audrey Michèle

    2015-01-01

    Effective conservation of marine fish stocks involves understanding the impact, on population dynamics, of intra-specific variation in nursery habitats use at the juvenile stage. In some regions, an important part of the catching effort is concentrated on a small number of marine species that colonize coastal lagoons during their first year of life. To determine the intra-specific variation in lagoon use by these fish and their potential demographic consequences, we studied diet spatiotemporal variations in the group 0 juveniles of a highly exploited sparid, the gilthead seabream (Sparus aurata L.), during their ∼6 months stay in a NW Mediterranean lagoon (N = 331, SL = 25-198 mm) and traced the origin of the organic matter in their food webs, at two lagoon sites with contrasted continental inputs. This showed that the origin (marine, lagoonal or continental) of the organic matter (OM) available in the water column and the sediment can vary substantially within the same lagoon, in line with local variations in the intensity of marine and continental inputs. The high trophic plasticity of S. aurata allows its juveniles to adapt to resulting differences in prey abundances at each site during their lagoon residency, thereby sustaining high growth irrespective of the area inhabited within the lagoon. However, continental POM incorporation by the juveniles through their diet (of 21-37% on average depending on the site) is proportional to its availability in the environment and could be responsible for the greater fish sizes (of 28 mm SL on average) and body weights (of 40.8 g on average) observed at the site under continental influence in the autumn, when the juveniles are ready to leave the lagoon. This suggests that continental inputs in particulate OM, when present, could significantly enhance fish growth within coastal lagoons, with important consequences on the local population dynamics of the fish species that use them as nurseries. As our results indicate that

  12. The reference phantoms: voxel vs polygon.

    Science.gov (United States)

    Kim, C H; Yeom, Y S; Nguyen, T T; Wang, Z J; Kim, H S; Han, M C; Lee, J K; Zankl, M; Petoussi-Henss, N; Bolch, W E; Lee, C; Chung, B S

    2016-06-01

    The International Commission on Radiological Protection (ICRP) reference male and female adult phantoms, described in Publication 110, are voxel phantoms based on whole-body computed tomography scans of a male and a female patient, respectively. The voxel in-plane resolution and the slice thickness, of the order of a few millimetres, are insufficient for proper segmentation of smaller tissues such as the lens of the eye, the skin, and the walls of some organs. The calculated doses for these tissues therefore present some limitations, particularly for weakly penetrating radiation. Similarly, the Publication 110 phantoms cannot represent 8-40-µm-thick target regions in respiratory or alimentary tract organs. Separate stylised models have been used to represent these tissues for calculation of the ICRP reference dose coefficients (DCs). ICRP Committee 2 recently initiated a research project, the ultimate goal of which is to convert the Publication 110 phantoms to a high-quality polygon-mesh (PM) format, including all source and target regions, even those of the 8-40-µm-thick alimentary and respiratory tract organs. It is expected that the converted phantoms would lead to the same or very similar DCs as the Publication 110 reference phantoms for penetrating radiation and, at the same time, provide more accurate DCs for weakly penetrating radiation and small tissues. Additionally, the reference phantoms in the PM format would be easily deformable and, as such, could serve as a starting point to create phantoms of various postures for use, for example, in accidental dose calculations. This paper will discuss the current progress of the phantom conversion project and its significance for ICRP DC calculations.

  13. Size exclusion and anion exchange high performance liquid chromatography for characterizing metals bound to marine dissolved organic matter

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Otero, Natalia; Bermejo-Barrera, Pilar [Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, University of Santiago de Compostela, Avenida das Ciencias, s/n, 15782 Santiago de Compostela (Spain); Moreda-Pineiro, Antonio, E-mail: antonio.moreda@usc.es [Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, University of Santiago de Compostela, Avenida das Ciencias, s/n, 15782 Santiago de Compostela (Spain)

    2013-01-14

    Highlights: Black-Right-Pointing-Pointer Fractionation methods for assessing metals bound to marine DOM were developed. Black-Right-Pointing-Pointer SEC and AEC with UV detection and hyphenated with inductively coupled plasma-mass spectrometry were used. Black-Right-Pointing-Pointer SEC-UV showed marine DOM of molecular weights from 16 to 1 kDa. Black-Right-Pointing-Pointer Cobalt, manganese, strontium and zinc are bound to marine DOM. - Abstract: Size exclusion chromatography (SEC) followed by anion exchange chromatography (AEC) hyphenated with inductively coupled plasma-mass spectrometry (ICP-MS) was applied for fractionating metals bound to marine dissolved organic matter (DOM). Surface seawater samples (100 L) were subjected to tangential flow ultrafiltration (10,000 Da cut off) for isolating and pre-concentrating dissolved large molecules. The isolated fraction (retentate) consisted of 1 L, which was further freeze-dried and re-dissolved to 250 mL with ultrapure water. After HI Trap desalting of the re-dissolved retentate, SEC with UV detection showed marine DOM ranging from 6.5 kDa (lower than the permeable volume of the SEC column) to 16 kDa. A further characterization of this fraction by AEC with UV detection revealed the existence of four groups of macromolecules exhibiting retention times of 2.3, 2.8, 4.5 and 14.0 min. AEC hyphenated with ICP-MS showed the presence of strontium and zinc in the first AE fraction isolated from the SEC fraction; while manganese was found to be bound to the second AE fraction. Cobalt was found to be bound to molecules comprising the third AE fraction.

  14. The effect of size-segregated ambient particulate matter on Th1/Th2-like immune responses in mice

    Science.gov (United States)

    Liu, Szu-Yuan; Chou, Charles C. K.; Lee, Yi-Hsin; Cheng, Tsun-Jen

    2017-01-01

    Background Particulate matter (PM) has been associated with increased pulmonary and cardiovascular mortality and morbidity. Additionally, PM is known to exacerbate asthma. However, whether ambient PM exposure contributes to the onset of asthma, especially in non-atopic children and adults, is less conclusive. The current study aimed to evaluate the effects of size-fractioned PM on lung immune responses in healthy BALB/c mice. Methods and principal findings We collected PM10, PM2.5, PM1 and PM0.1 samples from October 2012 to August 2013 in the Taipei Basin. These PM samples were representative of urban traffic pollution. The samples were extracted and sonicated in phosphate-buffered saline (PBS). Female BALB/c mice were exposed to the samples via intratracheal instillation at three different doses: 1.75 mg/kg (35 μg/per mouse), 5 mg/kg (100 μg/per mouse), and 12.5 mg/kg (250 μg/per mouse). The mice were exposed on days 0 and 7, and PBS alone was used as a control. Following the exposures, the expression profiles of inflammatory cells and cytokines in bronchoalveolar lavage fluid (BALF) were assessed. Exposure to PM10 resulted in inflammatory responses, including the recruitment of neutrophils and the induction of T helper 1 (Th1) cell-related cytokine release, such as TNF-α and IFN-γ. Furthermore, an allergic immune response, including the recruitment of eosinophils and the up-regulation of T helper 2 (Th2) cell-related cytokine release, such as IL-5 and IL-13, was also observed in the BALF of mice exposed to PM10. Conclusions Our study showed that exposure to PM alone caused mixed Th1/Th2 inflammatory responses in healthy mice. These findings support the hypothesis that PM may contribute to the onset of asthma. PMID:28245275

  15. Vessel-guided airway segmentation based on voxel classification

    DEFF Research Database (Denmark)

    2008-01-01

    This paper presents a method for improving airway tree segmentation using vessel orientation information. We use the fact that an airway branch is always accompanied by an artery, with both structures having similar orientations. This work is based on a  voxel classification airway segmentation...... method proposed previously. The probability of a voxel belonging to the airway, from the voxel classification method, is augmented with an orientation similarity measure as a criterion for region growing. The orientation similarity measure of a voxel indicates how similar is the orientation...... of the surroundings of a voxel, estimated based on a tube model, is to that of a neighboring vessel. The proposed method is tested on 20 CT images from different subjects selected randomly from a lung cancer screening study. Length of the airway branches from the results of the proposed method are significantly...

  16. Hippocampal and neocortical metabolite ratio in patients with complex partial seizure: short TE and long TE techniques using single voxel proton MR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Jin Il; Kim, Dong Ik; Lee, Byung In; Lee, Seung Ik; Yoon, Pyeong Ho [Medical College, Yonsei University, Seoul (Korea, Republic of)

    2000-08-01

    To compare hippocampal and neocortical metabolite ratios using single-voxel proton MR spectroscopy with different echo times in patients with complex partial seizure. Using a GE Signa 1.5T scanner with STEAM and PRESS sequences, automated single voxel proton MRS was used to determine metabolite ratio differences in the hippocampus and neocortex of nine complex partial seizure patients (mesial temporal sclerosis (n=3D5), status epilepticus (n=3D1), tumor (n=3D1), cortical dysplasia (n=3D1), occipital lobe epilepsy (n=3D1)). A total of 20 examinations were performed in the region of the hippocampus (n=3D17), temporal neocortex (n=3D1), and parieto-occipital gray matter (n=3D1). Voxel size range was 5.2-17.4 cm{sup 3}. The calculated creatine (Cr) peak was employed as an internal reference and the relative ratio of N-acetylaspartate (NAA) and choline (Cho) was calculated for both short and long echo times using an automated PROBE/SV (GE Medical Systems) package. Each NAA/Cho ratio obtained using both PRESS and STEAM techniques was compared by means of statistical analysis (paired Student t-test). Using PRESS (long TE, 272 ms), NAA/Cho ratios were successfully calculated in 16 of 20 examinations; in four this was not possible due to noise levels of the Cr and Cho peaks. Using STEAM (short TE, 30 ms) NAA/Cho ratios were successfully calculated in 19 of 20 examinations; in one, the Cho peak could not be measured. Using PRESS and STEAM, mean and standard deviations for the NAA/Cho ratio were 1.22{+-}0.50 and 1.16{+-}0.36, respectively. There were no statistically significant differences in this ratio between the short and long TE method (p less than 0.01). In complex partial seizure patients, no significant metabolite differences were found between short and long echo times of single voxel proton MR spectroscopy. The metabolite ratio at different echo times can be reliably obtained using this simplified and automated PROBE/SV quantitation method. (author)

  17. Different traits of gray matter volume in general anxiety disorder and obsessive compulsive disorder:A voxel-based morphometric study%广泛性焦虑障碍和强迫障碍的基于体素的大脑灰质体积研究

    Institute of Scientific and Technical Information of China (English)

    阎浩; 黄悦勤; 刘肇瑞; 韩鸿宾; 张岱

    2015-01-01

    structural MRI scan.The severity of anxiety and OCD symptoms were rated in all patients with the Hamilton Anxiety Rating Scale (HAMA)and the Yale-Brown Obsessive Compulsive Scale (Y-BOCS).The gray matter volume (GMV)was compared between all groups by using the voxel-based morphometry (VBM)a- nalysis.The correlation analysis between GMV and total scores of HAMA and Y-BOCS was performed in GAD and OCD.Results:The GMV was increased in regions including left anterior cingulate cortex in GAD (P =0.016,small volume correction),while only decreased GMV was observed in OCD in bilateral orbitofrontal cortex (OFC)(P <0.001,uncorrected).GAD had larger GMV than OCD in several regions including bilateral OFC (P <0.001,un-corrected).The higher total score of HAMA was associated with increased GMV of right temporal cortex in GAD, and with the GMV of OFC in OCD (P <0.001,uncorrected).Conclusion:No sharing of GMV abnormalities in GAD and OCD was observed in the current study.The traits of brain structure and the potential neural substrate of anxiety symptom in GAD and OCD may be significantly different.

  18. Size-resolved source apportionment of carbonaceous particulate matter in urban and rural sites in central California

    Science.gov (United States)

    Ham, Walter A.; Kleeman, Michael J.

    2011-08-01

    Very little is currently known about the relationship between exposure to different sources of ambient ultrafine particles (PM 0.1) and human health effects. If human health effects are enhanced by PM 0.1's ability to cross cell membranes, then more information is needed describing the sources of ultrafine particles that are deposited in the human respiratory system. The current study presents results for the source apportionment of airborne particulate matter in six size fractions smaller than 1.8 μm particle diameter including ultrafine particles (PM 0.1) in one of the most polluted air basins in the United States. Size-resolved source apportionment results are presented at an urban site and rural site in central California's heavily polluted San Joaquin Valley during the winter and summer months using a molecular marker chemical mass balance (MM-CMB) method. Respiratory deposition calculations for the size-resolved source apportionment results are carried out with the Multiple Path Particle Dosimetry Model ( MPPD v 2.0), including calculations for ultrafine (PM 0.1) source deposition. Diesel engines accounted for the majority of PM 0.1 and PM 1.8 EC at both the urban and rural sampling locations during both summer and winter seasons. Meat cooking accounted for 33-67% and diesel engines accounted for 15-21% of the PM 0.1 OC at Fresno. Meat cooking accounted for 22-26% of the PM 0.1 OC at the rural Westside location, while diesel engines accounted for 8-9%. Wood burning contributions to PM 0.1 OC increased to as much as 12% of PM 0.1 OC during the wintertime. The modest contribution of wood smoke reflects the success of emissions control programs over the past decade. In contrast to PM 0.1, PM 1.8 OC had a higher fraction of unidentified source contributions (68-85%) suggesting that this material is composed of secondary organic aerosol (SOA) or primary organic aerosol (POA) that has been processed by atmospheric chemical reactions. Meat cooking was the largest

  19. Suspended Matter, Chl-a, CDOM, Grain Sizes, and Optical Properties in the Arctic Fjord-Type Estuary, Kangerlussuaq, West Greenland During Summer

    DEFF Research Database (Denmark)

    Lund-Hansen, L. C.; Andersen, T. J.; Nielsen, Morten Holtegaard

    2010-01-01

    attenuation coefficient of downwelling PAR (K (d)(PAR)), upwelling PAR (K (u)(PAR)), particle beam attenuation coefficient (c (p)), and irradiance reflectance R(-0, PAR). PAR is white light between 400 and 700 nm. The estuary receives melt water from the Greenland Inland Ice and stations covered a transect......Optical constituents as suspended particulate matter (SPM), chlorophyll (Chl-a), colored dissolved organic matter (CDOM), and grain sizes were obtained on a transect in the arctic fjord-type estuary Kangerlussuaq (66A degrees) in August 2007 along with optical properties. These comprised diffuse...... from the very high turbid melt water outlet to clear marine waters. Results showed a strong spatial variation with high values as for suspended matter concentrations, CDOM, diffuse attenuation coefficient K (d)(PAR), particle beam attenuation coefficients (c (p)), and reflectance R(-0, PAR) at the melt...

  20. Construction tool and suitability of voxel phantom for skin dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Antunes, Paula C.G.; Siqueira, Paulo T.D.; Fonseca, Gabriel P.; Yoriyaz, Helio, E-mail: ptsiquei@ipen.b, E-mail: hyoriyaz@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    This paper describes a new software tool called 'SkinVop' which was developed to enable accurate voxel phantom skin dosimetry. A voxel phantom is a model used to describe human anatomy in a realistic way in radiation transport codes. This model is a three-dimensional representation of the human body in the form of an array of identification numbers that are arranged in a 3D matrix. Each entry in this array represents a voxel (volume element) directly associated to the units of picture resolution (pixel) of medical images. Currently, these voxel phantoms, in association with the transport code MCNP (Monte Carlo N-Particle), have provided subsidies to the planning systems used on the hospital routine, once they afford accurate and personalized estimative of dose distribution. However, these assessments are limited to geometric representations of organs and tissues in the voxel phantom, which do not discriminates some thin body structure, such as the skin. In this context, to enable accurate dosimetric skin dose assessment by the MCNP code, it was developed this new software tool that discriminates this region with thickness and localization in the voxel phantoms similar to the real. This methodology consists in manipulating the skin volume elements by segmenting and subdividing them in different thicknesses. A graphical user interface was designed to fulfill display the modified voxel model. This methodology is extremely useful once the skin dose is inaccurately assessed of current hospital system planning, justified justly by its small thickness. (author)

  1. ODVBA: optimally-discriminative voxel-based analysis.

    Science.gov (United States)

    Zhang, Tianhao; Davatzikos, Christos

    2011-08-01

    Gaussian smoothing of images prior to applying voxel-based statistics is an important step in voxel-based analysis and statistical parametric mapping (VBA-SPM) and is used to account for registration errors, to Gaussianize the data and to integrate imaging signals from a region around each voxel. However, it has also become a limitation of VBA-SPM based methods, since it is often chosen empirically and lacks spatial adaptivity to the shape and spatial extent of the region of interest, such as a region of atrophy or functional activity. In this paper, we propose a new framework, named optimally-discriminative voxel-based analysis (ODVBA), for determining the optimal spatially adaptive smoothing of images, followed by applying voxel-based group analysis. In ODVBA, nonnegative discriminative projection is applied regionally to get the direction that best discriminates between two groups, e.g., patients and controls; this direction is equivalent to local filtering by an optimal kernel whose coefficients define the optimally discriminative direction. By considering all the neighborhoods that contain a given voxel, we then compose this information to produce the statistic for each voxel. Finally, permutation tests are used to obtain a statistical parametric map of group differences. ODVBA has been evaluated using simulated data in which the ground truth is known and with data from an Alzheimer's disease (AD) study. The experimental results have shown that the proposed ODVBA can precisely describe the shape and location of structural abnormality.

  2. Neural correlates of anxiety in healthy volunteers: a voxel-based morphometry study.

    Science.gov (United States)

    Spampinato, Maria Vittoria; Wood, Jacqueline N; De Simone, Veronica; Grafman, Jordan

    2009-01-01

    Studies have shown that the amygdala, temporal, and prefrontal cortices play a key role in the expression of anxiety. The correlation between gray matter volume of these structures and behavioral anxiety measures was not previously investigated in healthy volunteers. The authors used voxel-based morphometry to assess the relationship between brain regional volume and anxiety. The authors found an inverse correlation between anxiety measures and cortical volume in regions of the limbic system and prefrontal cortex implicated in the pathogenesis of anxiety disorders. The authors suggest that volumetric variability of these regions may have a correlation with the development of an anxious personality trait.

  3. Growth rate and size effect on carbon isotopic fractionation in diatom-bound organic matter in recent Southern Ocean sediments

    Science.gov (United States)

    Stoll, Heather M.; Mendez-Vicente, Ana; Abrevaya, Lorena; Anderson, Robert F.; Rigual-Hernández, Andrés S.; Gonzalez-Lemos, Saul

    2017-01-01

    Carbon isotopic fractionation during photosynthesis (εp) is used to reconstruct past CO2 and phytoplankton growth rates, typically by measuring the δ13C of biomarkers produced by coccolithophorids. However, organic molecules bound within diatom frustules represent another phase for measurement of δ13C and offer the opportunity to obtain εp for specific diatom sizes and geometries. Here, from core top sediments covering a strong productivity gradient in the Southern Ocean, we present determinations of δ13C and εp from frustule-bound organic matter from a fine opal fraction dominated by pennate diatoms and a coarse opal fraction dominated by larger centric diatoms. The δ13C of the pennate diatom fraction is typically 2.8‰ more positive than that of the centric fraction. Both fractions show a comparable range of 9-10‰ over the core top transect. εp is lowest (6.3‰ in pennate fraction) between the Polar Front (PF) and Southern Antarctic Circumpolar Current Front (SACCF) and increases both to the north and south, with maximum values at greatest distance from the PF (18‰ in the pennate fraction). These spatial changes in εp are too large to arise from the rather modest variation in dissolved CO2 in surface waters across the core top transect. We suggest instead that the maximum εp reflects higher diatom growth rates, and in the case of pennate diatom F. kerguelensis also an increase in the frustule width and volume to surface area ratio. Both processes may result from enhanced Fe supply due to upwelling of circumpolar deep water between the PF and SACCF. Farther south, diatom growth is strongly Fe-limited and farther north it is Fe and Si co-limited. The optima of growth rates between the PF and SACCF appears to be a general feature in all sectors of the Southern Ocean. Such growth rate-induced changes in diatom εp allow us to resolve a 5° northward displacement of the PF during glacial times compared to interglacial times. By estimating CO2 aq in

  4. The influence of the strain, flush and size of carpophores on the yield and dry matter content of button mushroom (Agaricus bisporus (Lange Imbach carpophores

    Directory of Open Access Journals (Sweden)

    Alina Kałużewicz

    2016-06-01

    Full Text Available The aim of the experiment was to obtain information about the yield quantity and quality of 16 cultivated strains of Agaricus bisporus. The ‘Somycel 516’ strain gave the highest yield, whereas the yield from the ‘Sylvan 130’ strain was the lowest. The ‘Hauser A1.5’ was characterised by the highest content of dry matter in all the three yield flushes. An equally high content of dry matter was in the first and second flush of the ‘Italspawn F 50’ strain and in the second flash of the strain ‘Italspawn F 62’. ‘Sylvan S100’, ‘Italspawn F 56’, ‘Irlandzka 501’, ‘Amycel 104’ and ‘Le Lion X13’ were the strains with the lowest content of dry matter in all of the three yield flushes. The size of the carpophores had significant influence on the dry matter content. In the all three flushes, the carpophores with diameter 4.6–5.5 cm were characterized by the lowest dry matter content.

  5. Does size really matter? A multisite study assessing the latent structure of the proposed ICD-11 and the DSM-5 diagnostic criteria for PTSD

    DEFF Research Database (Denmark)

    Hansen, Maj; Hyland, Philip; Karstoft, Karen-Inge

    2017-01-01

    ,213), chronic pain patients (N = 573), and military personnel (N = 118). Results. Diagnostic rates of PTSD were significantly lower according to the proposed ICD-11 criteria in the university sample, but no significant differences were found for chronic pain patients and military personnel. The proposed ICD-11...... diagnostic criteria only the ICD-11 model can reflect the configuration of symptoms satisfactorily. Thus, size does matter when assessing PTSD....

  6. Voxel-by-voxel analysis of brain SPECT perfusion in Fibromyalgia

    Energy Technology Data Exchange (ETDEWEB)

    Guedj, Eric [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France)]. E-mail: eric.guedj@ap-hm.fr; Taieb, David [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France); Cammilleri, Serge [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France); Lussato, David [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France); Laforte, Catherine de [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France); Niboyet, Jean [Unite d' Etude et de Traitement de la Douleur, Clinique La Phoceanne, Marseille (France); Mundler, Olivier [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France)

    2007-02-01

    We evaluated brain perfusion SPECT at rest, without noxious stiumuli, in a homogeneous group of hyperalgesic FM patients. We performed a voxel-based analysis in comparison to a control group, matched for age and gender. Under such conditions, we made the assumption that significant cerebral perfusion abnormalities could be demonstrated, evidencing altered cerebral processing associated with spontaneous pain in FM patients. The secondary objective was to study the reversibility and the prognostic value of such possible perfusion abnormalities under specific treatment. Eighteen hyperalgesic FM women (mean age 48 yr; range 25-63 yr; ACR criteria) and 10 healthy women matched for age were enrolled in the study. A voxel-by-voxel group analysis was performed using SPM2 (p<0.05, corrected for multiple comparisons). All brain SPECT were performed before any change was made in therapy in the pain care unit. A second SPECT was performed a month later after specific treatment by Ketamine. Compared to control subjects, we observed individual brain SPECT abnormalities in FM patients, confirmed by SPM2 analysis with hyperperfusion of the somatosensory cortex and hypoperfusion of the frontal, cingulate, medial temporal and cerebellar cortices. We also found that a medial frontal and anterior cingulate hypoperfusions were highly predictive (PPV=83%; NPV=91%) of non-response on Ketamine, and that only responders showed significant modification of brain perfusion, after treatment. In the present study performed without noxious stimuli in hyperalgesic FM patients, we found significant hyperperfusion in regions of the brain known to be involved in sensory dimension of pain processing and significant hypoperfusion in areas assumed to be associated with the affective dimension. As current pharmacological and non-pharmacological therapies act differently on both components of pain, we hypothesize that SPECT could be a valuable and readily available tool to guide individual therapeutic

  7. Voxel-by-voxel analysis of brain SPECT perfusion in Fibromyalgia

    Science.gov (United States)

    Guedj, Eric; Taïeb, David; Cammilleri, Serge; Lussato, David; de Laforte, Catherine; Niboyet, Jean; Mundler, Olivier

    2007-02-01

    We evaluated brain perfusion SPECT at rest, without noxious stiumuli, in a homogeneous group of hyperalgesic FM patients. We performed a voxel-based analysis in comparison to a control group, matched for age and gender. Under such conditions, we made the assumption that significant cerebral perfusion abnormalities could be demonstrated, evidencing altered cerebral processing associated with spontaneous pain in FM patients. The secondary objective was to study the reversibility and the prognostic value of such possible perfusion abnormalities under specific treatment. Eighteen hyperalgesic FM women (mean age 48 yr; range 25-63 yr; ACR criteria) and 10 healthy women matched for age were enrolled in the study. A voxel-by-voxel group analysis was performed using SPM2 ( ppain care unit. A second SPECT was performed a month later after specific treatment by Ketamine. Compared to control subjects, we observed individual brain SPECT abnormalities in FM patients, confirmed by SPM2 analysis with hyperperfusion of the somatosensory cortex and hypoperfusion of the frontal, cingulate, medial temporal and cerebellar cortices. We also found that a medial frontal and anterior cingulate hypoperfusions were highly predictive (PPV=83%; NPV=91%) of non-response on Ketamine, and that only responders showed significant modification of brain perfusion, after treatment. In the present study performed without noxious stimuli in hyperalgesic FM patients, we found significant hyperperfusion in regions of the brain known to be involved in sensory dimension of pain processing and significant hypoperfusion in areas assumed to be associated with the affective dimension. As current pharmacological and non-pharmacological therapies act differently on both components of pain, we hypothesize that SPECT could be a valuable and readily available tool to guide individual therapeutic strategy and provide objective follow-up of pain-processing recovery under treatment.

  8. Dynamic voxel modeling resolution based on quality assessments from LIDAR path tracing

    Science.gov (United States)

    Hagstrom, Shea; Broadwater, Joshua

    2015-05-01

    Airborne LIDAR instruments are capable of delivering high density point clouds, but sampling is inherently uneven in both 2D and 3D space due to collection patterns as well as effects like occlusion. Taking full advantage of the detail available when creating 3D models therefore requires that resolution be adaptable to the amount of localized data. Voxel-based modeling of LIDAR has proven advantageous in many situations, but the traditional use of a fixed grid size prevents full realization of the potential resolution. Allowing voxel sizes to vary across the model using spatial subdivision techniques overcomes this limitation. An important part of this process is defining an appropriate limit of resolution for different sections of a model, and we incorporate information gained through tracing of LIDAR pulses to guide this decision process. Real-world data are used to demonstrate our results, and we show how dynamic resolution voxelization of LIDAR allows for both reduced storage requirements as well as improved modeling flexibility.

  9. Stable carbon and radiocarbon isotope compositions of particle size fractions to determine origins of sedimentary organic matter in an estuary

    NARCIS (Netherlands)

    Megens, L; van der Plicht, J; de Leeuw, JW; Smedes, F; Altabet, M.

    2002-01-01

    Stable and radioactive carbon isotopic compositions of particle size fractions of a surface sediment from the Ems-Dollard estuary vary considerably with particle size. The organic material in the fine fractions (

  10. Stable carbon and radiocarbon isotope compositions of particle size fractions to determine origins of sedimentary organic matter in an estuary

    NARCIS (Netherlands)

    Megens, L; van der Plicht, J; de Leeuw, JW; Smedes, F; Altabet, M.

    2002-01-01

    Stable and radioactive carbon isotopic compositions of particle size fractions of a surface sediment from the Ems-Dollard estuary vary considerably with particle size. The organic material in the fine fractions (

  11. Simulation of computed tomography dose based on voxel phantom

    Science.gov (United States)

    Liu, Chunyu; Lv, Xiangbo; Li, Zhaojun

    2017-01-01

    Computed Tomography (CT) is one of the preferred and the most valuable imaging tool used in diagnostic radiology, which provides a high-quality cross-sectional image of the body. It still causes higher doses of radiation to patients comparing to the other radiological procedures. The Monte-Carlo method is appropriate for estimation of the radiation dose during the CT examinations. The simulation of the Computed Tomography Dose Index (CTDI) phantom was developed in this paper. Under a similar conditions used in physical measurements, dose profiles were calculated and compared against the measured values that were reported. The results demonstrate a good agreement between the calculated and the measured doses. From different CT exam simulations using the voxel phantom, the highest absorbed dose was recorded for the lung, the brain, the bone surface. A comparison between the different scan type shows that the effective dose for a chest scan is the highest one, whereas the effective dose values during abdomen and pelvis scan are very close, respectively. The lowest effective dose resulted from the head scan. Although, the dose in CT is related to various parameters, such as the tube current, exposure time, beam energy, slice thickness and patient size, this study demonstrates that the MC simulation is a useful tool to accurately estimate the dose delivered to any specific organs for patients undergoing the CT exams and can be also a valuable technique for the design and the optimization of the CT x-ray source.

  12. Size does matter - Determination of the critical molecular size for the uptake of chemicals across the chorion of zebrafish (Danio rerio) embryos.

    Science.gov (United States)

    Pelka, Katharina E; Henn, Kirsten; Keck, Andreas; Sapel, Benjamin; Braunbeck, Thomas

    2016-12-21

    In order to identify the upper limits of the molecular size of chemicals to cross the chorion of zebrafish, Danio rerio, differently sized, non-toxic and chemically inert polyethylene glycols (PEGs; 2000-12,000Da) were applied at concentrations (9.76mM) high enough to provoke osmotic pressure. Whereas small PEGs were expected to be able to cross the chorion, restricted uptake of large PEGs was hypothesized to result in shrinkage of the chorion. Due to a slow, but gradual uptake of PEGs over time, molecular size-dependent equilibration in conjunction with a regain of the spherical chorion shape was observed. Thus, the size of molecules able to cross the chorion could be narrowed down precisely to ≤4000Da, and the time-dependency of the movement across the chorion could be described. To account for associated alterations in embryonic development, fish embryo toxicity tests (FETs) according to OECD test guideline 236 (OECD, 2013) were performed with special emphasis to changes in chorion shape. FETs revealed clear-cut size-effects: the higher the actual molecular weight (=size) of the PEG, the more effects (both acutely toxic and sublethal) were found. No effects were seen with PEGs of 2000 and 3000Da. In contrast, PEG 8000 and PEG 12,000 were found to be most toxic with LC50 values of 16.05 and 16.40g/L, respectively. Likewise, the extent of chorion shrinkage due to increased osmotic pressure strictly depended on PEG molecular weight and duration of exposure. A reflux of water and PEG molecules into the chorion and a resulting re-shaping of the chorion could only be observed for eggs exposed to PEGs ≤4000Da. Results clearly indicate a barrier function of the zebrafish chorion for molecules larger than 3000 to 4,000Da.

  13. Geometric features for voxel-based surface recognition

    OpenAIRE

    Yarotsky, Dmitry

    2017-01-01

    We introduce a library of geometric voxel features for CAD surface recognition/retrieval tasks. Our features include local versions of the intrinsic volumes (the usual 3D volume, surface area, integrated mean and Gaussian curvature) and a few closely related quantities. We also compute Haar wavelet and statistical distribution features by aggregating raw voxel features. We apply our features to object classification on the ESB data set and demonstrate accurate results with a small number of s...

  14. Efficient simulation of voxelized phantom in GATE with embedded SimSET multiple photon history generator

    Science.gov (United States)

    Lin, Hsin-Hon; Chuang, Keh-Shih; Lin, Yi-Hsing; Ni, Yu-Ching; Wu, Jay; Jan, Meei-Ling

    2014-10-01

    spectra for energy below 50 keV due to the lack of x-ray simulation from 124I decay in the new code. The spatial resolution, scatter fraction and count rate performance are in good agreement between the two codes. For the case studies of 18F-NaF (124I-IAZG) using MOBY phantom with 1  ×  1 × 1 mm3 voxel sizes, the results show that GATE/MPHG can achieve acceleration factors of approximately 3.1 × (4.5 ×), 6.5 × (10.7 ×) and 9.5 × (31.0 ×) compared with GATE using the regular navigation method, the compressed voxel method and the parameterized tracking technique, respectively. In conclusion, the implementation of MPHG in GATE allows for improved efficiency of voxelized phantom simulations and is suitable for studying clinical and preclinical imaging.

  15. Voxel-based texture analysis of the brain.

    Science.gov (United States)

    Maani, Rouzbeh; Yang, Yee Hong; Kalra, Sanjay

    2015-01-01

    This paper presents a novel voxel-based method for texture analysis of brain images. Texture analysis is a powerful quantitative approach for analyzing voxel intensities and their interrelationships, but has been thus far limited to analyzing regions of interest. The proposed method provides a 3D statistical map comparing texture features on a voxel-by-voxel basis. The validity of the method was examined on artificially generated effects as well as on real MRI data in Alzheimer's Disease (AD). The artificially generated effects included hyperintense and hypointense signals added to T1-weighted brain MRIs from 30 healthy subjects. The AD dataset included 30 patients with AD and 30 age/sex matched healthy control subjects. The proposed method detected artificial effects with high accuracy and revealed statistically significant differences between the AD and control groups. This paper extends the usage of texture analysis beyond the current region of interest analysis to voxel-by-voxel 3D statistical mapping and provides a hypothesis-free analysis tool to study cerebral pathology in neurological diseases.

  16. Multi-Scale Voxel Segmentation for Terrestrial Lidar Data within Marshes

    Science.gov (United States)

    Nguyen, C. T.; Starek, M. J.; Tissot, P.; Gibeaut, J. C.

    2016-12-01

    The resilience of marshes to a rising sea is dependent on their elevation response. Terrestrial laser scanning (TLS) is a detailed topographic approach for accurate, dense surface measurement with high potential for monitoring of marsh surface elevation response. The dense point cloud provides a 3D representation of the surface, which includes both terrain and non-terrain objects. Extraction of topographic information requires filtering of the data into like-groups or classes, therefore, methods must be incorporated to identify structure in the data prior to creation of an end product. A voxel representation of three-dimensional space provides quantitative visualization and analysis for pattern recognition. The objectives of this study are threefold: 1) apply a multi-scale voxel approach to effectively extract geometric features from the TLS point cloud data, 2) investigate the utility of K-means and Self Organizing Map (SOM) clustering algorithms for segmentation, and 3) utilize a variety of validity indices to measure the quality of the result. TLS data were collected at a marsh site along the central Texas Gulf Coast using a Riegl VZ 400 TLS. The site consists of both exposed and vegetated surface regions. To characterize structure of the point cloud, octree segmentation is applied to create a tree data structure of voxels containing the points. The flexibility of voxels in size and point density makes this algorithm a promising candidate to locally extract statistical and geometric features of the terrain including surface normal and curvature. The characteristics of the voxel itself such as the volume and point density are also computed and assigned to each point as are laser pulse characteristics. The features extracted from the voxelization are then used as input for clustering of the points using the K-means and SOM clustering algorithms. Optimal number of clusters are then determined based on evaluation of cluster separability criterions. Results for

  17. A voxel-based morphometry and diffusion tensor imaging analysis of asymptomatic Parkinson's disease-related G2019S LRRK2 mutation carriers

    NARCIS (Netherlands)

    Thaler, A.; Artzi, M.; Mirelman, A.; Jacob, Y.; Helmich, R.C.G.; Nuenen, B.F.L. van; Gurevich, T.; Orr-Urtreger, A.; Marder, K.; Bressman, S.; Bloem, B.R.; Hendler, T.; Giladi, N.; Bashat, D. Ben

    2014-01-01

    BACKGROUND: Patients with Parkinson's disease have reduced gray matter volume and fractional anisotropy in both cortical and sub-cortical structures, yet changes in the pre-motor phase of the disease are unknown. METHODS: A comprehensive imaging study using voxel-based morphometry and diffusion tens

  18. Voxel Based Morphometry Alterations in Mal de Debarquement Syndrome.

    Directory of Open Access Journals (Sweden)

    Yoon-Hee Cha

    Full Text Available Mal de debarquement syndrome (MdDS is a disorder of chronic self-motion perception that occurs though entrainment to rhythmic background motion, such as from sea voyage, and involves the perception of low-frequency rocking that can last for months or years. The neural basis of this persistent sensory perception abnormality is not well understood.We investigated grey matter volume differences underlying persistent MdDS by performing voxel-based morphometry on whole brain and pre-specified ROIs in 28 individuals with MdDS and comparing them to 18 age, sex, and handedness matched controls.MdDS participants exhibited greater grey matter volume in the left inferior parietal lobule, right inferior occipital gyrus (area V3v, right temporal pole, bilateral cerebellar hemispheric lobules VIII/IX and left lobule VIIa/VIIb. Grey matter volumes were lower in bilateral inferior frontal, orbitofrontal, pregenual anterior cingulate cortex (pgACC and left superior medial gyri (t = 3.0, p<0.005uncorr. In ROI analyses, there were no volume differences in the middle occipital gyrus (region of V5/MT or parietal operculum 2 (region of the parietoinsular vestibular cortex. Illness duration was positively related to grey matter volume in bilateral inferior frontal gyrus/anterior insula (IFG/AI, right posterior insula, superior parietal lobule, left middle occipital gyrus (V5/MT, bilateral postcentral gyrus, anterior cerebellum, and left cerebellar hemisphere and vermian lobule IX. In contrast, illness duration was negatively related to volume in pgACC, posterior middle cingulate gyrus (MCC, left middle frontal gyrus (dorsolateral prefrontal cortex-DLPFC, and right cerebellar hemispheric lobule VIIIb (t = 3.0, p<0.005uncorr. The most significant differences were decreased volume in the pgACC and increased volume in the left IFG/AI with longer illness duration (qFDRcorr <0.05. Concurrent medication use did not correlate with these findings or have a relationship with

  19. Development and tests of a mouse voxel model dor MCNPX based on Digimouse images

    Energy Technology Data Exchange (ETDEWEB)

    Melo M, B.; Ferreira F, C. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Pte. Antonio Carlos No. 6627, Belo Horizonte 31270-901, Minas Gerais (Brazil); Garcia de A, I.; Machado T, B.; Passos Ribeiro de C, T., E-mail: bmm@cdtn.br [Universidade Federal de Minas Gerais, Departamento de Engenharia Nuclear, Pte. Antonio Carlos 6627, Belo Horizonte 31270-901, Minas Gerais (Brazil)

    2015-10-15

    Mice have been widely used in experimental protocols involving ionizing radiation. Biological effects (Be) induced by radiation can compromise studies results. Good estimates of mouse whole body and organs absorbed dose could provide valuable information to researchers. The aim of this study was to create and test a new voxel phantom for mice dosimetry from -Digimouse- project images. Micro CT images from Digimouse project were used in this work. Corel PHOTOPAINT software was utilized in segmentation process. The three-dimensional (3-D) model assembly and its voxel size manipulation were performed by Image J. SISCODES was used to adapt the model to run in MCNPX Monte Carlo code. The resulting model was called DM{sub B}RA. The volume and mass of segmented organs were compared with data available in literature. For the preliminary tests the heart was considered the source organ. Photons of diverse energies were simulated and Saf values obtained through F6:p and + F6 MCNPX tallies. The results were compared with reference data. 3-D picturing of absorbed doses patterns and relative errors distribution were generated by a C++ -in house- made program and visualized through Amide software. The organ masses of DM{sub B}RA correlated well with two models that were based on same set of images. However some organs, like eyes and adrenals, skeleton and brain showed large discrepancies. Segmentation of an identical image set by different persons and/or methods can result significant organ masses variations. We believe that the main causes of these differences were: i) operator dependent subjectivity in the definition of organ limits during the segmentation processes; and i i) distinct voxel dimensions between evaluated models. Lack of reference data for mice models construction and dosimetry was detected. Comparison with other models originated from different mice strains also demonstrated that the anatomical and size variability can be significant. Use of + F6 tally for mouse

  20. Absorbed dose evaluation based on a computational voxel model incorporating distinct cerebral structures

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Samia de Freitas; Trindade, Bruno; Campos, Tarcisio P.R. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)]. E-mail: samiabrandao@gmail.com; bmtrindade@yahoo.com; campos@nuclear.ufmg.br

    2007-07-01

    Brain tumors are quite difficult to treat due to the collateral radiation damages produced on the patients. Despite of the improvements in the therapeutics protocols for this kind of tumor, involving surgery and radiotherapy, the failure rate is still extremely high. This fact occurs because tumors can not often be totally removed by surgery since it may produce some type of deficit in the cerebral functions. Radiotherapy is applied after the surgery, and both are palliative treatments. During radiotherapy the brain does not absorb the radiation dose in homogeneous way, because the various density and chemical composition of tissues involved. With the intention of evaluating better the harmful effects caused by radiotherapy it was developed an elaborated cerebral voxel model to be used in computational simulation of the irradiation protocols of brain tumors. This paper presents some structures function of the central nervous system and a detailed cerebral voxel model, created in the SISCODES program, considering meninges, cortex, gray matter, white matter, corpus callosum, limbic system, ventricles, hypophysis, cerebellum, brain stem and spinal cord. The irradiation protocol simulation was running in the MCNP5 code. The model was irradiated with photons beam whose spectrum simulates a linear accelerator of 6 MV. The dosimetric results were exported to SISCODES, which generated the isodose curves for the protocol. The percentage isodose curves in the brain are present in this paper. (author)

  1. Structural covariance in the hallucinating brain: a voxel-based morphometry study

    Science.gov (United States)

    Modinos, Gemma; Vercammen, Ans; Mechelli, Andrea; Knegtering, Henderikus; McGuire, Philip K.; Aleman, André

    2009-01-01

    Background Neuroimaging studies have indicated that a number of cortical regions express altered patterns of structural covariance in schizophrenia. The relation between these alterations and specific psychotic symptoms is yet to be investigated. We used voxel-based morphometry to examine regional grey matter volumes and structural covariance associated with severity of auditory verbal hallucinations. Methods We applied optimized voxel-based morphometry to volumetric magnetic resonance imaging data from 26 patients with medication-resistant auditory verbal hallucinations (AVHs); statistical inferences were made at p < 0.05 after correction for multiple comparisons. Results Grey matter volume in the left inferior frontal gyrus was positively correlated with severity of AVHs. Hallucination severity influenced the pattern of structural covariance between this region and the left superior/middle temporal gyri, the right inferior frontal gyrus and hippocampus, and the insula bilaterally. Limitations The results are based on self-reported severity of auditory hallucinations. Complementing with a clinician-based instrument could have made the findings more compelling. Future studies would benefit from including a measure to control for other symptoms that may covary with AVHs and for the effects of antipsychotic medication. Conclusion The results revealed that overall severity of AVHs modulated cortical intercorrelations between frontotemporal regions involved in language production and verbal monitoring, supporting the critical role of this network in the pathophysiology of hallucinations. PMID:19949723

  2. Structural composition of organic matter in particle-size fractions of soils along a climo-biosequence in the main range of Peninsular Malaysia

    Science.gov (United States)

    Jafarzadeh-Haghighi, Amir Hossein; Shamshuddin, Jusop; Hamdan, Jol; Zainuddin, Norhazlin

    2016-09-01

    Information on structural composition of organic matter (OM) in particle-size fractions of soils along a climo-biosequence is sparse. The objective of this study was to examine structural composition and morphological characteristics of OM in particle-size fractions of soils along a climo-biosequence in order to better understand the factors and processes affecting structural composition of soil organic matter. To explore changes in structural composition of OM in soils with different pedogenesis, the A-horizon was considered for further analyses including particle-size fractionation, solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM). Due to the increase in the thickness of organic layer with increasing elevation, the A-horizon was situated at greater depth in soils of higher elevation. The relationship between relative abundances of carbon (C) structures and particle-size fractions was examined using principal component analysis (PCA). It was found that alkyl C (20.1-73.4%) and O-alkyl C (16.8-67.7%) dominated particle-size fractions. The proportion of alkyl C increased with increasing elevation, while O-alkyl C showed an opposite trend. Results of PCA confirmed this finding and showed the relative enrichment of alkyl C in soils of higher elevation. Increase in the proportion of alkyl C in 250-2000 μm fraction is linked to selective preservation of aliphatic compounds derived from root litter. SEM results showed an increase in root contribution to the 250-2000 μm fraction with increasing elevation. For the responsible for the relative enrichment of alkyl C. This study demonstrates that changes in structural composition of OM in particle-size fractions of soils along the studied climo-biosequence are attributed to site-specific differences in pedogenesis as a function of climate and vegetation.

  3. Brain gray matter volume changes associated with motor symptoms in patients with Parkinson's disease

    Institute of Scientific and Technical Information of China (English)

    Dezhi Kang; Fuyong Chen; Fangyu Wang; Guorong Wu; Ying Liu; Gang Wu; Lianghong Yu

    2016-01-01

    Background:Parkinson's disease (PD) is a common neurodegenerative disease.Most studies have found that the histopathological lesion is not only localized at the extrapyramidal area (basal ganglia) but also at the cortex in PD patients.Voxel-based morphometry (VBM) based on the voxel as a unit is described for quantitative detection of density and volume of brain tissue.In this study,VBM was used to investigate the brain gray matter changes associated with motor symptoms in PD patients.Methods:Twelve outpatients with PD and 12 healthy controls were recruited in our hospital from September 2013 to March 2014.VBM was performed on the whole brain of all subjects.Image processing and statistical analysis were performed using SPM8.A two-sample t test and multiple regression analysis were performed.Results were displayed with a threshold of P < 0.01,corrected by false discovery rate (FDR) correction and cluster size >30 voxels.Results:Comparing control healthy subjects with the patients,the data showed that PD patients had reduced gray matter volume in the postcentral gyrus,the right supramarginal center,superior temporal gyrus,precentral gyrus,Brodmann area 41,transverse temporal gyrus,Brodmann area 3,and inferior parietal Iobule.The data also found that between gray matter volume and UPDRSIII in PD patients,there were negative correlations in the right middle frontal gyrus,BA06,right precentral gyrus,right superior frontal gyrus,and medial frontal gyrus,and between gray matter volume and Hoehn-Yahr (HY) in PD patients,there were negative correlations in the right middle frontal gyrus,right superior frontal gyrus,BA6,and right precentral gyrus.Conclusions:These data supported that extensive changes associated with motor symptoms in the gray matter volume was mainly located in the related area of movement,which had obvious relevance with the progression of PD.

  4. The size does not matter – The presence of microvascular obstruction but not its extent corresponds to larger infarct size in reperfused STEMI

    Energy Technology Data Exchange (ETDEWEB)

    Małek, Łukasz A., E-mail: lmalek@ikard.pl [Department of Interventional Cardiology and Angiology, Institute of Cardiology, Warsaw (Poland); Śpiewak, Mateusz, E-mail: mspiewak@ikard.pl [Department of Coronary Artery Disease and Structural Heart Diseases, Institute of Cardiology, Warsaw (Poland); Kłopotowski, Mariusz, E-mail: mklopotowski@hotmail.com [Department of Interventional Cardiology and Angiology, Institute of Cardiology, Warsaw (Poland); Miśko, Jolanta, E-mail: jmisko@wp.pl [Magnetic Resonance Unit, Department of Radiology, Institute of Cardiology, Warsaw (Poland); Rużyłło, Witold, E-mail: wruzyllo@ikard.pl [Institute of Cardiology, Warsaw (Poland); Witkowski, Adam, E-mail: witkowski@hbz.pl [Department of Interventional Cardiology and Angiology, Institute of Cardiology, Warsaw (Poland)

    2012-10-15

    Background: Microvascular obstruction (MVO) is a cardiac magnetic resonance (CMR) marker of no-reflow in ST-segment elevation myocardial infarction (STEMI). It remains unresolved whether the infarct size corresponds only to the presence of MVO or also to its extent. Methods: The study included 53 patients with first STEMI (median age 61.5 years, 77% male) treated with percutaneous coronary intervention (PCI) who underwent CMR after median 5 days from PCI. Small MVO was defined as patchy, non-confluent spots of dark areas of absent contrast surrounded by late gadolinium enhancement (LGE). Large MVO was defined as confluent areas of MVO comprising a large amount of the infarct zone. Results: Microvascular obstruction was observed in 32 patients (60%) including 18 patients with small MVO (36%) and 14 patients with large MVO (24%). Patients with MVO were more likely to have TIMI 0/1 grade flow on initial angiogram, higher levels of necrotic markers, larger infarct size, larger left ventricular end-diastolic and end-systolic volume and lower ejection fraction in comparison to patients without MVO. These differences were not observed between patients with large and small MVO. Conclusions: The presence of MVO but not its extent corresponds to larger infarct size in STEMI.

  5. A Voxel-based Method for Forest Change Detection after Fire Using LiDAR Data

    Science.gov (United States)

    Xu, Z.

    2015-12-01

    A Voxel-based Method for Forest Change Detection after Fire Using LiDAR DataZewei Xu and Jonathan A. Greenberg Traditional methods of forest fire modeling focus on the patterns of burning in two-dimensions at relatively coarse resolutions. However, fires spread in complex, three-dimensional patterns related to the horizontal and vertical distributions of woody fuel as well as the prevailing climate conditions, and the micro-scale patterns of fuel distributions over scales of only meters can determine the path that fire can take through a complex landscape. One challenge in understanding the full three-dimensional (3D) path that a fire takes through a landscape is a lack of data at landscape scales of these burns. Remote sensing approaches, while operating at landscape scales, typically focus on two-dimensional analyses using standard image-based change detection techniques. In this research, we develop a 3D voxel-based change detection method applied to multitemporal LiDAR data collected before and after forest fires in California to quantify the full 3D pattern of vegetation loss. By changing the size of the voxel, forest loss at different spatial scales is revealed. The 3D tunnel of fuel loss created by the fire was used to examine ground-to-crown transitions, firebreaks, and other three-dimensional aspects of a forest fire.

  6. Size matters at deep-sea hydrothermal vents: different diversity and habitat fidelity patterns of meio- and macrofauna

    NARCIS (Netherlands)

    Gollner, S.; Govenar, B.; Fisher, C.R.; Bright, M.

    2015-01-01

    Species with markedly different sizes interact when sharing the same habitat. Unravelling mechanisms that control diversity thus requires consideration of a range of size classes. We compared patterns of diversity and community structure for meio- and macrofaunal communities sampled along a gradient

  7. 75 FR 447 - In the Matter of Certain Semiconductor Chips With Minimized Chip Package Size and Products...

    Science.gov (United States)

    2010-01-05

    ... Certain Semiconductor Chips With Minimized Chip Package Size and Products Containing Same (III); Notice of... States after importation of certain semiconductor chips with minimized chip package size or products... Semiconductor Corporation of Hsinchu, Taiwan; ProMOS Technologies, Inc. of Hsinchu, Taiwan; Ramaxel...

  8. The partitioning behavior of persistent toxicant organic contaminants in eutrophic sediments: Coefficients and effects of fluorescent organic matter and particle size.

    Science.gov (United States)

    He, Wei; Yang, Chen; Liu, Wenxiu; He, Qishuang; Wang, Qingmei; Li, Yilong; Kong, Xiangzhen; Lan, Xinyu; Xu, Fuliu

    2016-12-01

    In the shallow lakes, the partitioning of organic contaminants into the water phase from the solid phase might pose a potential hazard to both benthic and planktonic organisms, which would further damage aquatic ecosystems. This study determined the concentrations of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and phthalate esters (PAEs) in both the sediment and the pore water from Lake Chaohu and calculated the sediment - pore water partition coefficient (KD) and the organic carbon normalized sediment - pore water partition coefficient (KOC), and explored the effects of particle size, organic matter content, and parallel factor fluorescent organic matter (PARAFAC-FOM) on KD. The results showed that log KD values of PAHs (2.61-3.94) and OCPs (1.75-3.05) were significantly lower than that of PAEs (4.13-5.05) (p  PAHs (4.61-5.86) > OCPs (3.62-4.97). A modified MCI model can predict KOC values in a range of log 1.5 at a higher frequency, especially for PAEs. The significantly positive correlation between KOC and the octanol - water partition coefficient (KOW) were observed for PAHs and OCPs. However, significant correlation was found for PAEs only when excluding PAEs with lower KOW. Sediments with smaller particle sizes (clay and silt) and their organic matter would affect distributions of PAHs and OCPs between the sediment and the pore water. Protein-like fluorescent organic matter (C2) was associated with the KD of PAEs. Furthermore, the partitioning of PARAFAC-FOM between the sediment and the pore water could potentially affect the distribution of organic pollutants. The partitioning mechanism of PAEs between the sediment and the pore water might be different from that of PAHs and OCPs, as indicated by their associations with influencing factors and KOW.

  9. Mimicking Dark Matter

    OpenAIRE

    Bel, Lluís

    2017-01-01

    I show that a very simple model in the context of Newtonian physics promoted to a first approximation of general relativity can mimic Dark matter and explain most of its intriguing properties. Namely: i) Dark matter is a halo associated to ordinary matter; ii) Dark matter does not interact with ordinary matter nor with itself; iii) Its influence grows with the size of the aggregate of ordinary matter that is considered, and iv) Dark matter influences the propagation of light.

  10. Segmentation Based Classification of 3D Urban Point Clouds: A Super-Voxel Based Approach with Evaluation

    Directory of Open Access Journals (Sweden)

    Laurent Trassoudaine

    2013-03-01

    Full Text Available Segmentation and classification of urban range data into different object classes have several challenges due to certain properties of the data, such as density variation, inconsistencies due to missing data and the large data size that require heavy computation and large memory. A method to classify urban scenes based on a super-voxel segmentation of sparse 3D data obtained from LiDAR sensors is presented. The 3D point cloud is first segmented into voxels, which are then characterized by several attributes transforming them into super-voxels. These are joined together by using a link-chain method rather than the usual region growing algorithm to create objects. These objects are then classified using geometrical models and local descriptors. In order to evaluate the results, a new metric that combines both segmentation and classification results simultaneously is presented. The effects of voxel size and incorporation of RGB color and laser reflectance intensity on the classification results are also discussed. The method is evaluated on standard data sets using different metrics to demonstrate its efficacy.

  11. Voxel inversion of airborne electromagnetic data for improved model integration

    Science.gov (United States)

    Fiandaca, Gianluca; Auken, Esben; Kirkegaard, Casper; Vest Christiansen, Anders

    2014-05-01

    Inversion of electromagnetic data has migrated from single site interpretations to inversions including entire surveys using spatial constraints to obtain geologically reasonable results. Though, the model space is usually linked to the actual observation points. For airborne electromagnetic (AEM) surveys the spatial discretization of the model space reflects the flight lines. On the contrary, geological and groundwater models most often refer to a regular voxel grid, not correlated to the geophysical model space, and the geophysical information has to be relocated for integration in (hydro)geological models. We have developed a new geophysical inversion algorithm working directly in a voxel grid disconnected from the actual measuring points, which then allows for informing directly geological/hydrogeological models. The new voxel model space defines the soil properties (like resistivity) on a set of nodes, and the distribution of the soil properties is computed everywhere by means of an interpolation function (e.g. inverse distance or kriging). Given this definition of the voxel model space, the 1D forward responses of the AEM data are computed as follows: 1) a 1D model subdivision, in terms of model thicknesses, is defined for each 1D data set, creating "virtual" layers. 2) the "virtual" 1D models at the sounding positions are finalized by interpolating the soil properties (the resistivity) in the center of the "virtual" layers. 3) the forward response is computed in 1D for each "virtual" model. We tested the new inversion scheme on an AEM survey carried out with the SkyTEM system close to Odder, in Denmark. The survey comprises 106054 dual mode AEM soundings, and covers an area of approximately 13 km X 16 km. The voxel inversion was carried out on a structured grid of 260 X 325 X 29 xyz nodes (50 m xy spacing), for a total of 2450500 inversion parameters. A classical spatially constrained inversion (SCI) was carried out on the same data set, using 106054

  12. Proinflammatory and cytotoxic effects of Mexico City air pollution particulate matter in vitro are dependent on particle size and composition.

    OpenAIRE

    2003-01-01

    Exposure to urban airborne particulate matter (PM) is associated with adverse health effects. We previously reported that the cytotoxic and proinflammatory effects of Mexico City PM10 (less than or equal to 10 micro m mean aerodynamic diameter) are determined by transition metals and endotoxins associated with these particles. However, PM2.5 (less than or equal to 2.5 micro m mean aerodynamic diameter) could be more important as a human health risk because this smaller PM has the potential to...

  13. Voxel Based Segmentation of Large Airborne Topobathymetric LIDAR Data

    Science.gov (United States)

    Boerner, R.; Hoegner, L.; Stilla, U.

    2017-05-01

    Point cloud segmentation and classification is currently a research highlight. Methods in this field create labelled data, where each point has additional class information. Current approaches are to generate a graph on the basis of all points in the point cloud, calculate or learn descriptors and train a matcher for the descriptor to the corresponding classes. Since these approaches need to look on each point in the point cloud iteratively, they result in long calculation times for large point clouds. Therefore, large point clouds need a generalization, to save computation time. One kind of generalization is to cluster the raw points into a 3D grid structure, which is represented by small volume units ( i.e. voxels) used for further processing. This paper introduces a method to use such a voxel structure to cluster a large point cloud into ground and non-ground points. The proposed method for ground detection first marks ground voxels with a region growing approach. In a second step non ground voxels are searched and filtered in the ground segment to reduce effects of over-segmentations. This filter uses the probability that a voxel mostly consist of last pulses and a discrete gradient in a local neighbourhood . The result is the ground label as a first classification result and connected segments of non-ground points. The test area of the river Mangfall in Bavaria, Germany, is used for the first processing.

  14. Natural organic matter alters size-dependent effects of nanoCuO on the feeding behaviour of freshwater invertebrate shredders.

    Science.gov (United States)

    Pradhan, Arunava; Geraldes, Paulo; Seena, Sahadevan; Pascoal, Cláudia; Cássio, Fernanda

    2015-12-01

    Nanoparticle size and the presence of natural organic matter (NOM) may influence the toxicity of nanoCuO to aquatic biota, but their interactive effects have been poorly investigated. We examined the feeding behaviour of the invertebrate shredder Allogamus ligonifer when exposed to sublethal concentrations of nanoCuO (50 and 100 mg L(-1)) with three particle sizes (12, 50 and 80 nm) in the absence or presence of humic acid (HA, 100 mg L(-1)) as a proxy of NOM. We further examined the ability of invertebrates to recover from the stressors. In the absence of nanoCuO and HA, the feeding rate of shredders was 0.416 mg leaf DM mg(-1 )animal DM day(-1). The exposure to increased nanoCuO concentrations inhibited the feeding rate and effects were stronger as nanoparticle size decreased (up to 83.3% inhibition for 12 nm particles). The exposure to HA alone inhibited the feeding activity by 52.7%. However, the co-exposure to nanoCuO and HA alleviated the inhibitory effects promoted by smaller and medium sized nanoCuO (up to 29.5%). The recovery of feeding activity by the shredders after stress removal was very low; maximum recovery (16.7%) was found for invertebrates rescued from pre-exposure to lower concentration of nanoCuO with larger size.

  15. Probing the dark matter radial profile in lens galaxies and the size of X-ray emitting region in quasars with microlensing

    CERN Document Server

    Jiménez-Vicente, J; Kochanek, C S; Muñoz, J A

    2015-01-01

    We use X-ray and optical microlensing measurements of 47 image pairs in 18 lens systems to study the shape of the dark matter density profile in the lens galaxies and the size of the (soft) X-ray emission region. We show that single epoch X-ray microlensing is sensitive to the source size. Our results, in good agreement with previous estimates, show that the X-ray size scales roughly linearly with the black hole mass, with a half light radius of $R_{1/2}\\simeq(20\\pm12) r_g$ (for $r_g=GM_{BH}/c^2$). This corresponds to a size of $\\sim$ 1 light day for a black hole mass of $M_{BH}=10^9 M_\\sun$. We simultaneously estimated the fraction of the local surface mass density in stars, finding that the stellar mass fraction is $\\alpha=0.20\\pm0.05$ at an average radius of $\\sim 1.9 R_{e}$, where $R_e$ is the effective radius of the lens. This stellar mass fraction is insensitive to the X-ray source size and in excellent agreement with our earlier results based on optical data. By combining the X-ray and optical microlen...

  16. Brain structure in post-traumatic stress disorder A voxel-based morphometry analysis**

    Institute of Scientific and Technical Information of China (English)

    Liwen Tan; Li Zhang; Rongfeng Qi; Guangming Lu; Lingjiang Li; Jun Liu; Weihui Li

    2013-01-01

    This study compared the difference in brain structure in 12 mine disaster survivors with chronic post-traumatic stress disorder, 7 cases of improved post-traumatic stress disorder symptoms, and 14 controls who experienced the same mine disaster but did not suffer post-traumatic stress disorder, us-ing the voxel-based morphometry method. The correlation between differences in brain structure and post-traumatic stress disorder symptoms was also investigated. Results showed that the gray matter volume was the highest in the trauma control group, fol owed by the symptoms-improved group, and the lowest in the chronic post-traumatic stress disorder group. Compared with the symptoms-improved group, the gray matter volume in the lingual gyrus of the right occipital lobe was reduced in the chronic post-traumatic stress disorder group. Compared with the trauma control group, the gray matter volume in the right middle occipital gyrus and left middle frontal gyrus was reduced in the symptoms-improved group. Compared with the trauma control group, the gray matter volume in the left superior parietal lobule and right superior frontal gyrus was reduced in the chronic post-traumatic stress disorder group. The gray matter volume in the left superior parietal lobule was significantly positively correlated with the State-Trait Anxiety Inventory subscale score in the symptoms-improved group and chronic post-traumatic stress disorder group (r = 0.477, P = 0.039). Our findings indicate that (1) chronic post-traumatic stress disorder patients have gray matter structural damage in the prefrontal lobe, occip-ital lobe, and parietal lobe, (2) after post-traumatic stress, the disorder symptoms are improved and gray matter structural damage is reduced, but cannot recover to the trauma-control level, and (3) the superior parietal lobule is possibly associated with chronic post-traumatic stress disorder. Post-traumatic stress disorder patients exhibit gray matter abnormalities.

  17. Brain structure in post-traumatic stress disorder: A voxel-based morphometry analysis.

    Science.gov (United States)

    Tan, Liwen; Zhang, Li; Qi, Rongfeng; Lu, Guangming; Li, Lingjiang; Liu, Jun; Li, Weihui

    2013-09-15

    This study compared the difference in brain structure in 12 mine disaster survivors with chronic post-traumatic stress disorder, 7 cases of improved post-traumatic stress disorder symptoms, and 14 controls who experienced the same mine disaster but did not suffer post-traumatic stress disorder, using the voxel-based morphometry method. The correlation between differences in brain structure and post-traumatic stress disorder symptoms was also investigated. Results showed that the gray matter volume was the highest in the trauma control group, followed by the symptoms-improved group, and the lowest in the chronic post-traumatic stress disorder group. Compared with the symptoms-improved group, the gray matter volume in the lingual gyrus of the right occipital lobe was reduced in the chronic post-traumatic stress disorder group. Compared with the trauma control group, the gray matter volume in the right middle occipital gyrus and left middle frontal gyrus was reduced in the symptoms-improved group. Compared with the trauma control group, the gray matter volume in the left superior parietal lobule and right superior frontal gyrus was reduced in the chronic post-traumatic stress disorder group. The gray matter volume in the left superior parietal lobule was significantly positively correlated with the State-Trait Anxiety Inventory subscale score in the symptoms-improved group and chronic post-traumatic stress disorder group (r = 0.477, P = 0.039). Our findings indicate that (1) chronic post-traumatic stress disorder patients have gray matter structural damage in the prefrontal lobe, occipital lobe, and parietal lobe, (2) after post-traumatic stress, the disorder symptoms are improved and gray matter structural damage is reduced, but cannot recover to the trauma-control level, and (3) the superior parietal lobule is possibly associated with chronic post-traumatic stress disorder. Post-traumatic stress disorder patients exhibit gray matter abnormalities.

  18. Speciation of organic matter in sandy soil size fractions as revealed by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy

    Science.gov (United States)

    Jiménez-Morillo, Nicasio T.; González-Vila, Francisco J.; Jordán, Antonio; Zavala, Lorena M.; de la Rosa, José M.; González-Pérez, José A.

    2015-04-01

    This research deals with the assessment of organic matter structural differences in soil physical fractions before and after lipid extractions. Soil samples were collected in sandy soils, Arenosols (WRB 2006) from the Doñana National Park (SW Spain) under different vegetation cover: cork oak (Quercus suber, QS), eagle fern (Pteridium aquilinum, PA), pine (Pinus pinea, PP) and rockrose (Halimium halimifolium, HH). Two size fractions; coarse (C: 1-2 mm) and fine (F: 0.05-0.25 mm) were studied from each soil. . In addition, the two fractions from each soil were exhaustively Soxhlet extracted with a Dichlorometane-Methanol (3:1) mixture to obtain the lipid-free fractions (LF) from each size fraction (LFC and LFF). The composition of the organic matter at a molecular level in the different soil fractions was approached by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy. These techniques are complementary and have been found suitable for the structural characterization of complex organic matrices (Moldoveanu, 1998; Piccolo and Stevenson, 1982); whereas Py-GC/MS provides detailed structural information of individual compounds present and a finger-printing of soil organic matter, FT-IR is informative about major functional groups present. The advantages of these techniques are well known: no need for pretreatment are fast to perform, highly reproducible and only small amount of samples are needed. Soil size fractions show contrasting differences in organic matter content (C 4-7 % and F > 40 %) and conspicuous differences were found in the pyrolysis products released by the fractions studied. The main families of pyrolysis compounds have well defined macromolecular precursors, such as lignin, polypeptides, polysaccharides and lipids (González-Vila et al., 2001). The C fractions yield higher relative abundance of lignin and polysaccharide derived pyrolysis compounds. Regarding the differences in the soil organic matter as affected by the different vegetation covers

  19. Does Size Matter? Atmospheric CO2 May Be a Stronger Driver of Stomatal Closing Rate Than Stomatal Size in Taxa That Diversified under Low CO2

    Science.gov (United States)

    Elliott-Kingston, Caroline; Haworth, Matthew; Yearsley, Jon M.; Batke, Sven P.; Lawson, Tracy; McElwain, Jennifer C.

    2016-01-01

    One strategy for plants to optimize stomatal function is to open and close their stomata quickly in response to environmental signals. It is generally assumed that small stomata can alter aperture faster than large stomata. We tested the hypothesis that species with small stomata close faster than species with larger stomata in response to darkness by comparing rate of stomatal closure across an evolutionary range of species including ferns, cycads, conifers, and angiosperms under controlled ambient conditions (380 ppm CO2; 20.9% O2). The two species with fastest half-closure time and the two species with slowest half-closure time had large stomata while the remaining three species had small stomata, implying that closing rate was not correlated with stomatal size in these species. Neither was response time correlated with stomatal density, phylogeny, functional group, or life strategy. Our results suggest that past atmospheric CO2 concentration during time of taxa diversification may influence stomatal response time. We show that species which last diversified under low or declining atmospheric CO2 concentration close stomata faster than species that last diversified in a high CO2 world. Low atmospheric [CO2] during taxa diversification may have placed a selection pressure on plants to accelerate stomatal closing to maintain adequate internal CO2 and optimize water use efficiency. PMID:27605929

  20. The mid-domain effect matters: simulation analyses of range-size distribution data from Mount Kinabalu, Borneo

    DEFF Research Database (Denmark)

    Grytnes, John-Arvid; Beaman, John H.; Romdal, Tom Skovlund;

    2008-01-01

    Aim In simulation exercises, mid-domain peaks in species richness arise as a result of the random placement of modelled species ranges within simulated geometric constraints. This has been called the mid-domain effect (MDE). Where close correspondence is found between such simulations and empirical...... within the domain (range-restricted MDE), and a model encompassing all species with the theoretical midpoint within the domain (midpoint-restricted MDE). These predictions are compared with observations from the elevational pattern of range-size distributions and species richness of vascular plants....... The distribution of range sizes gives different predictions between models including the MDE or not. Here, we produce predictions for species richness and distribution of range sizes from one model without the MDE and from two MDE models: a classical MDE model encompassing only species with their entire range...

  1. Does size matter? Study of performance of pseudo-ELISAs based on molecularly imprinted polymer nanoparticles prepared for analytes of different sizes.

    Science.gov (United States)

    Cáceres, C; Canfarotta, F; Chianella, I; Pereira, E; Moczko, E; Esen, C; Guerreiro, A; Piletska, E; Whitcombe, M J; Piletsky, S A

    2016-02-21

    The aim of this work is to evaluate whether the size of the analyte used as template for the synthesis of molecularly imprinted polymer nanoparticles (nanoMIPs) can affect their performance in pseudo-enzyme linked immunosorbent assays (pseudo-ELISAs). Successful demonstration of a nanoMIPs-based pseudo-ELISA for vancomycin (1449.3 g mol(-1)) was demonstrated earlier. In the present investigation, the following analytes were selected: horseradish peroxidase (HRP, 44 kDa), cytochrome C (Cyt C, 12 kDa) biotin (244.31 g mol(-1)) and melamine (126.12 g mol(-1)). NanoMIPs with a similar composition for all analytes were synthesised by persulfate-initiated polymerisation in water. In addition, core-shell nanoMIPs coated with polyethylene glycol (PEG) and imprinted for melamine were produced in organics and tested. The polymerisation of the nanoparticles was done using a solid-phase approach with the correspondent template immobilised on glass beads. The performance of the nanoMIPs used as replacement for antibodies in direct pseudo-ELISA (for the enzymes) and competitive pseudo-ELISA for the smaller analytes was investigated. For the competitive mode we rely on competition for the binding to the nanoparticles between free analyte and corresponding analyte-HRP conjugate. The results revealed that the best performances were obtained for nanoMIPs synthesised in aqueous media for the larger analytes. In addition, this approach was successful for biotin but completely failed for the smallest template melamine. This problem was solved using nanoMIP prepared by UV polymerisation in an organic media with a PEG shell. This study demonstrates that the preparation of nanoMIP by solid-phase approach can produce material with high affinity and potential to replace antibodies in ELISA tests for both large and small analytes. This makes this technology versatile and applicable to practically any target analyte and diagnostic field.

  2. Differences between the Bud End and Stem End of Potatoes in Dry Matter Content, Starch Granule Size, and Carbohydrate Metabolic Gene Expression at the Growing and Sprouting Stages.

    Science.gov (United States)

    Liu, Bailin; Zhang, Guodong; Murphy, Agnes; De Koeyer, David; Tai, Helen; Bizimungu, Benoit; Si, Huaijun; Li, Xiu-Qing

    2016-02-10

    Potatoes usually have the tuber bud end dominance in growth during tuber bulking and in tuber sprouting, likely using carbohydrates from the tuber stem end. We hypothesized that the tuber bud end and tuber stem end coordination in carbohydrate metabolism gene expression is different between the bulking dominance and sprouting dominance of the tuber bud end. After comparing the growing tubers at harvest from a green vine and the stage that sprouts just started to emerge after storage of tubers at room temperature, we found the following: (1) Dry matter content was higher in the tuber stem end than the tuber bud end at both stages. (2) The starch granule size was larger in the tuber bud end than in the tuber stem end. (3) The tuber bud end had higher gene expression for starch synthesis but a lower gene expression of sucrose transporters than the tuber stem end during tuber growing. (4) The tuber stem end at the sprouting stage showed more active gene expression in both starch degradation and resynthesis, suggesting more active export of carbohydrates, than the tuber bud end. The results indicate that the starch accumulation mechanism in the tuber bud end was different between field growing and post-harvest sprouting tubers and that tubers already increased dry matter and average starch granule sizes in the tuber bud end prior to the rapid growth of sprouts.

  3. Relations between the Sizes of Galaxies and Their Dark Matter Halos at Redshifts 0 < z < 3

    Science.gov (United States)

    Huang, Kuang-Han; Fall, S. Michael; Ferguson, Henry C.; van der Wel, Arjen; Grogin, Norman; Koekemoer, Anton; Lee, Seong-Kook; Pérez-González, Pablo G.; Wuyts, Stijn

    2017-03-01

    We derive relations between the effective radii R eff of galaxies and the virial radii R 200c of their dark matter halos over the redshift range 0 purpose, we derive a new SMHM relation based on the same selection criteria and other assumptions as for our sample of galaxies with size measurements. As a check on the robustness of our results, we also derive R eff–R 200c relations for three independent SMHM relations from the literature. We find that galaxy R eff is proportional on average to halo R 200c , confirming and extending to high redshifts the z = 0 results of Kravtsov. Late-type galaxies (with low Sérsic index and high specific star formation rate (sSFR)) follow a linear R eff–R 200c relation, with effective radii at 0.5 < z < 3 close to those predicted by simple models of disk formation; at z < 0.5, the sizes of late-type galaxies appear to be slightly below this prediction. Early-type galaxies (with high Sérsic index and low sSFR) follow a roughly parallel R eff–R 200c relation, ∼0.2–0.3 dex below the one for late-type galaxies. Our observational results, reinforced by recent hydrodynamical simulations, indicate that galaxies grow quasi-homologously with their dark matter halos.

  4. Assessment of particulate matter in the urban atmosphere: size distribution, metal composition and source characterization using principal component analysis.

    Science.gov (United States)

    Onat, Burcu; Alver Şahin, Ülkü; Bayat, Cuma

    2012-05-01

    In this study, the size distribution of airborne particles and related heavy metals Co, Cd, Sn, Cu, Ni, Cr, Pb and V in two urban areas in Istanbul: Yenibosna and Goztepe, were examined. The different inhalable particles were collected by using a cascade impactor in eight size fractions (9 μm) for six months at each station. Samples were collected on glass fiber filters and filters were extracted and analyzed using ICP-MS. Log-normal distributions showed that the particles collected at the Yenibosna site have a smaller size compared to the Goztepe samples and the size distribution of PM was represented the best by the tri-modal. The average total particle concentrations and standard deviations were obtained as 67.7 ± 17.0 μg m(-3) and 82.1 ± 21.2 μg m(-3), at the Yenibosna and Göztepe sites, respectively. The higher metal rate in fine and medium coarse PM showed that the anthropogenic sources were the most significant pollutant source. Principal component analysis identified five components for PM namely traffic, road dust, coal and fuel oil combustion, and industrial.

  5. Vocabulary Size Matters: The Assimilation of Second-Language Australian English Vowels to First-Language Japanese Vowel Categories

    Science.gov (United States)

    Bundgaard-Nielsen, Rikke L.; Best, Catherine T.; Tyler, Michael D.

    2011-01-01

    Adult second-language (L2) learners' perception of L2 phonetic segments is influenced by first-language phonological and phonetic properties. It was recently proposed that L2 vocabulary size in adult learners is related to changes in L2 perception (perceptual assimilation model), analogous to the emergence of first-language phonological function…

  6. How much does size really matter? Exploring the limits of graphene as Li ion battery anode material

    Science.gov (United States)

    Sun, H.; Varzi, A.; Pellegrini, V.; Dinh, D. A.; Raccichini, R.; Del Rio-Castillo, A. E.; Prato, M.; Colombo, M.; Cingolani, R.; Scrosati, B.; Passerini, S.; Bonaccorso, F.

    2017-02-01

    We unravel the role of flake dimensionality on the lithiation/de-lithiation processes and electrochemical performance of anodes based on few-(FLG) and multi-layer graphene (MLG) flakes prepared by liquid phase exfoliation (LPE) of pristine graphite. The flakes are sorted by lateral size (from 380 to 75 nm) and thickness from 20 (MLG) to 2 nm (FLG) exploiting a sedimentation-based separation in centrifugal field and, finally, deposited onto Cu disks for the realization of four binder-free anodes. The electrochemical results show that decreasing lateral size and thickness leads to an increase of the initial specific capacity from ≈590 to ≈1270mAhg-1. However, an increasing irreversible capacity is also associated to the reduction of flakes' size. We find, in addition, that the preferential Li ions storage by adsorption rather than intercalation in small lateral size (<100 nm) FLG flakes has a detrimental effect on the average de-lithiation voltage, resulting on low voltage efficiency of these anodes. We believe that the results reported in this work, provide the guidelines for the practical exploitation of graphene-based electrodes.

  7. DTI analysis in patients with primary open-angle glaucoma: impact of registration on Voxel-Wise statistics.

    Directory of Open Access Journals (Sweden)

    Manuel A Schmidt

    Full Text Available BACKGROUND AND PURPOSE: Tract-based spatial statistics (TBSS has been used to assess the integrity of the visual pathway in glaucoma patients. TBSS uses the subjects' FA data to create a mean FA skeleton of white matter tracts before running voxel-wise cross-subject statistics. We compared four different approaches of registration of FA maps to create the skeleton and evaluated alignment and subsequently the impact of the chosen registration on voxel-wise statistics. MATERIAL AND METHODS: Our study comprised 69 subjects, i.e. 46 patients with primary open angle glaucoma (POAG and a healthy, age-matched control group of 23 subjects. Mean FA skeletons were created using the following registration approaches: registration to a standard template (T, registration to the group mean (GM, registration to a group-wise atlas (GW and registration to the most typical subject (N. Subsequently, maps of standard deviation of the 4D images were created to assess the alignment. Voxel-wise statistics for each registration approach were performed. RESULTS: We found distinct differences in voxel-wise statistics depending on the chosen registration approach. Best alignment results were achieved by registration to a study specific template, i.e. to the group mean (GM or to a group-wise atlas (GW. Overall alignment did not differ between these two approaches. However, voxel-wise statistics showed clusters of significantly decreased FA values in the T and GM approach, which were not significant after GW registration. These voxels of significantly decreased FA values after T and GM registration did not represent white matter tracts and correlated with higher standard deviation in FA maps across subjects, thus implying registration errors, especially in the optic radiation. CONCLUSION: Registration to a study-specific template, i.e. to the group mean or a group-wise atlas seems to be the method of choice in TBSS-analysis of glaucoma patients as it shows better alignment

  8. Cell size matters in gamma-H2AX assay for low-dose alpha particle effect assessment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ui seob; Kim, Eun Hee [Seoul National University, Daejeon (Korea, Republic of)

    2016-05-15

    Gamma-H2AX assay is an immuno-fluorescence experiment that enables detecting the location and number of DNA double strand breaks (DSBs) in cells. Under uniform radiation beam intensity, cells would respond with similar numbers of gamma-H2AX if they are similar in cross section. If cells are not represented by a common size, however, a larger cell has a greater chance of radiation exposure and has a better chance of counting a greater number of foci. In other words, the cell size distribution would be reflected in the FPC distribution. In the conventional gamma-H2AX assay, the mean FPC value solely indicates the level of cellular damage under a certain radiation exposure. The purpose of this study is to investigate the FPC distribution in connection with the cell size distribution. The high-LET alpha beam was employed for radiation exposure so that a single track of radiation leaves a meaningful amount of energy in the cell. Gamma-H2AX is a powerful tool for investigating the cellular response at low-dose exposure. If the gamma-H2AX assay is performed with cells of the same size, 'the average number of foci per cell' may accord with the overall response of sample cells to radiation exposure. With cells of non-uniform size, however, one should be cautious in taking the value as an index of the severity in cellular effect of radiation exposure. According to our experiments, a portion of sample cells carried DSBs of more than 5 times greater number than the mean FPC value and might play a critical role in radio-response.

  9. Fragment size does not matter when you are well connected: effects of fragmentation on fitness of coexisting gypsophiles.

    Science.gov (United States)

    Matesanz, S; Gómez-Fernández, A; Alcocer, I; Escudero, A

    2015-09-01

    Most habitat fragmentation studies have focused on the effects of population size on reproductive success of single species, but studies assessing the effects of both fragment size and connectivity, and their interaction, on several coexisting species are rare. In this study, we selected 20 fragments along two continuous gradients of size and degree of isolation in a gypsum landscape in central Spain. In each fragment, we selected 15 individuals of each of three dominant gypsophiles (Centaurea hyssopifolia, Lepidium subulatum and Helianthemum squamatum, 300 plants per species, 900 plants in total) and measured several reproductive traits: inflorescence number, fruit set, seed set and seed mass. We hypothesised that plant fitness would be lower on small and isolated fragments due to an interaction between fragment size and connectivity, and that response patterns would be species-specific. Overall, fragment size had very little effect on reproductive traits compared to that of connectivity. We observed a positive effect of fragment connectivity on C. hyssopifolia fitness, mediated by the increased seed predation in plants from isolated fragments, resulting in fewer viable seeds per capitulum and lower seed set. Furthermore, seed mass was lower in plants from isolated fragments for both C. hyssopifolia and L. subulatum. In contrast, few reproductive traits of H. squamatum were affected by habitat fragmentation. We discuss the implications of species-specific responses to habitat fragmentation for the dynamics and conservation of gypsum plant communities. Our results highlight the complex interplay among plants and their mutualistic and antagonistic visitors, and reinforce the often-neglected role of habitat connectivity as a key component of the fragmentation process.

  10. A Morphological Approach to the Voxelization of Solids

    DEFF Research Database (Denmark)

    Bærentzen, Jakob Andreas; Sramek, Milos; Christensen, Niels Jørgen

    2000-01-01

    In this paper we present a new, morphological criterion for determining whether a geometric solid is suitable for voxelization at a given resolution. The criterion embodies two conditions, namely that the curvature of the solid must be bounded and the critical points of the distance field must...... be at a certain distance from the boundary of the solid. For solids that fulfill this criterion, we present an analytic and an empirical bound for the trilinear reconstruction error. Additionally, we give a theoretical argument as to why the distance field approach to voxelization is more sound than...

  11. [Grain Size Distribution Characteristics of Suspended Particulate Matter as Influenced by the Apparent Pollution in the Eutrophic Urban Landscape Water Body].

    Science.gov (United States)

    Gong, Dan-yan; Pan, Yang; Huang, Yong; Bao, Wei; Li, Qian-qian

    2016-03-15

    Grain size distribution characteristics of suspended particulate matter (SPM) reflects the apparent polluted condition of the urban landscape water. In order to explore the internal relationship between the eutrophication of urban landscape water's apparent pollution and grain size distribution of SPM, and its influencing factors, this paper selected five representative sampling sites in Feng Jin River which is a typical eutrophication river in Suzhou City, measured the grain size distribution of SPM, sensation pollution index (SPI) and water quality index, and analyzed their correlation. The results showed that: The rich nutrient water possessed a similar characteristics in grain size distribution. The grain size distribution of SPM in water was multimodal, and the the peak position was roughly the same; the grain size distribution of SPM was composed by multiple components. It could be roughly divided into six parts with the particle size range of every group being 516 µm. The component III was superior (with an average volume fraction of 38.3%-43.2%), and its volume fraction had a significant positive relation with the SPI value and the Chl-a content. The increase of component III volume fraction was the reflection of particle size's result of increasing SPI value. The increase of component III volume fraction was mainly derived from the increasing algal content. The volume fraction of group IV + group VI + group V was significantly higher under the condition of exogenous enter. When there was no exogenous component, the volume fraction of group IV + group VI + group V had a significant negative correlation with SPI value; when there were exogenous components, the volume fraction of group IV + group VI + group V had a weak positive correlation with SPI value, but the correlation did not reach a significant level. Environmental factors (Fv/Fm and DO) and exogenous factors had an influence by functioning on the algal content which signified the polluted material

  12. Structural brain abnormalities in patients with Parkinson's disease with visual hallucinations: a comparative voxel-based analysis.

    Science.gov (United States)

    Gama, Romulo Lopes; Bruin, Veralice Meireles Sales; Távora, Daniel Gurgel Fernandes; Duran, Fábio L S; Bittencourt, Lia; Tufik, Sergio

    2014-06-01

    The objective is to evaluate clinical characteristics and cerebral alterations in Parkinson's disease (PD) patients with diurnal visual hallucinations (VHs). Assessment was performed using magnetic resonance image (MRI) and voxel-based morphometry (VBM). Thirty-nine patients with PD (53.8%) and ten controls were studied. Voxel based morphology analysis was performed. Eleven patients presented diurnal VHs and among these, six had cognitive dysfunction. Patients with VHs performed worse in the mentation-related UPDRS I (p=0.005) and motor-related UPDRS III (p=0.02). Patients with VHs showed significant clusters of reduced grey matter volume compared to controls in the left opercula frontal gyrus and left superior frontal gyrus. PD without hallucinations demonstrated reduced grey matter volume in the left superior frontal gyrus compared to controls. Comparisons between patients with VHs regarding the presence of cognitive dysfunction showed that cases with cognitive dysfunction as compared to those without cognitive dysfunction showed significant clusters of reduced grey matter volume in the left opercular frontal gyrus. Cases without cognitive dysfunction had reduced grey matter substance in the left insula and left trigonal frontal gyrus. Judging from our findings, an abnormal frontal cortex, particularly left sided insula, frontal opercular, trigonal frontal gyrus and orbital frontal would make PD patients vulnerable to hallucinations. Compromise of the left operculum distinguished cases with VHs and cognitive dysfunction. Our findings reinforce the theoretical concept of a top-down visual processing in the genesis of VHs in PD.

  13. Lipoprotein particle subclass profiles among metabolically healthy and unhealthy obese and non-obese adults: does size matter?

    Science.gov (United States)

    Phillips, Catherine M; Perry, Ivan J

    2015-10-01

    No data regards lipoprotein particle profiles in obese and non-obese metabolic health subtypes exist. We characterised lipoprotein size, particle and subclass concentrations among metabolically healthy and unhealthy obese and non-obese adults. Cross-sectional sample of 1834 middle-aged Irish adults were classified as obese (BMI ≥30 kg/m(2)) and non-obese (BMI Lipoprotein size, particle and subclass concentrations were determined using nuclear magnetic resonance (NMR) spectroscopy. Lipoprotein profiling identified a range of adverse phenotypes among the metabolically unhealthy individuals, regardless of BMI and metabolic health definition, including increased numbers of small low density lipoprotein (LDL) (P lipoprotein (HDL) particles (P lipoprotein (VLDL) particles (P lipoprotein related insulin resistance (P lipoprotein particle profiles, irrespective of BMI and metabolic health definition. These findings underscore the importance of maintaining a healthy lipid profile in the context of overall cardiometabolic health. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  14. Brain correlates of pro-social personality traits: a voxel-based morphometry study.

    Science.gov (United States)

    Coutinho, Joana F; Sampaio, Adriana; Ferreira, Miguel; Soares, José M; Gonçalves, Oscar F

    2013-09-01

    Of the five personality dimensions described by the Big Five Personality Model (Costa and McCrae 1992), Extraversion and Agreeableness are the traits most commonly associated with a pro-social orientation. In this study we tested whether a pro-social orientation, as expressed in terms of Extraversion and Agreeableness, is associated with a specific grey matter phenotype. Fifty-two healthy participants underwent magnetic resonance imaging (MRI) and completed the NEO-Five Factor Inventory (NEO-FFI), a self-report measure of the Big Five personality traits. Voxel-based morphometry (VBM) was used to investigate the correlation between brain structure and the personality traits of Agreeableness and Extraversion. We found that Extraversion was negatively correlated with grey matter density in the middle frontal and orbitofrontal gyri while Agreeableness was negatively correlated with grey matter density in the inferior parietal, middle occipital and posterior cingulate gyri. No positive correlations were found. These results suggest that pro-social personality traits seem to be associated with decreases in grey matter density in more frontal regions for Extraversion, and more posterior regions for Agreeableness.

  15. Regional brain structural abnormality in ischemic stroke patients: a voxel-based morphometry study

    Directory of Open Access Journals (Sweden)

    Ping Wu

    2016-01-01

    Full Text Available Our previous study used regional homogeneity analysis and found that activity in some brain areas of patients with ischemic stroke changed significantly. In the current study, we examined structural changes in these brain regions by taking structural magnetic resonance imaging scans of 11 ischemic stroke patients and 15 healthy participants, and analyzing the data using voxel-based morphometry. Compared with healthy participants, patients exhibited higher gray matter density in the left inferior occipital gyrus and right anterior white matter tract. In contrast, gray matter density in the right cerebellum, left precentral gyrus, right middle frontal gyrus, and left middle temporal gyrus was less in ischemic stroke patients. The changes of gray matter density in the middle frontal gyrus were negatively associated with the clinical rating scales of the Fugl-Meyer Motor Assessment (r = -0.609, P = 0.047 and the left middle temporal gyrus was negatively correlated with the clinical rating scales of the nervous functional deficiency scale (r = -0.737, P = 0.010. Our findings can objectively identify the functional abnormality in some brain regions of ischemic stroke patients.

  16. Mapping the brain in type II diabetes: Voxel-based morphometry using DARTEL.

    Science.gov (United States)

    Chen, Zhiye; Li, Lin; Sun, Jie; Ma, Lin

    2012-08-01

    To investigate the pattern of brain volume changes of the brain in patients with type II diabetes mellitus using voxel-based morphometry. Institutional ethics approval and informed consent were obtained. VBM based on the high resolution three-dimensional T1-weighted fast spoiled gradient recalled echo MRI images was obtained from 16 type II diabetes patients (mean age 61.2 years) and 16 normal controls (mean age 59.6 years). All images were spatially preprocessed using Diffeomorphic Anatomical Registration using Exponentiated Lie algebra (DARTEL) algorithm, and the DARTEL templates were made from 100 normal subjects. Statistical parametric mapping was generated using analysis of covariance (ANCOVA). An atrophy pattern of gray matter was seen in type II diabetes patients compared with controls that involved the right superior, middle, and inferior temporal gyri, right precentral gyrus, and left rolandic operculum region. The loss of white matter volume in type II diabetes mellitus was observed in right temporal lobe and left inferior frontal triangle region. ROI analysis revealed that the gray and white matter volume of right temporal lobe were significant lower in type II diabetes mellitus than that in controls (P<0.05). This work demonstrated that type II diabetes mellitus patients mainly exhibited gray and white matter atrophy in right temporal lobe, and this finding supported that type II diabetes mellitus could lead to subtle diabetic brain structural changes in patients without dementia or macrovascular complications. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  17. Regional brain structural abnormality in ischemic stroke patients:a voxel-based morphometry study

    Institute of Scientific and Technical Information of China (English)

    Ping Wu; Lin Chen; Lin Bai; Juan Nie; San Zhang; Yan Xiong; Yu Bai; Can-xin Yin; Fan-rong Liang; Yu-mei Zhou; Fang Zeng; Zheng-jie Li; Lu Luo; Yong-xin Li; Wei Fan; Li-hua Qiu; Wei Qin

    2016-01-01

    Our previous study used regional homogeneity analysis and found that activity in some brain areas of patients with ischemic stroke changed signiifcantly. In the current study, we examined structural changes in these brain regions by taking structural magnetic resonance imaging scans of 11 ischemic stroke patients and 15 healthy participants, and analyzing the data using voxel-based morphometry. Compared with healthy participants, patients exhibited higher gray matter density in the left inferior occipital gyrus and right anterior white matter tract. In contrast, gray matter density in the right cerebellum, left precentral gyrus, right middle frontal gyrus, and left middle temporal gyrus was less in ischemic stroke patients. The changes of gray matter density in the middle frontal gyrus were negatively associated with the clin-ical rating scales of the Fugl-Meyer Motor Assessment (r = –0.609,P = 0.047) and the left middle temporal gyrus was negatively correlated with the clinical rating scales of the nervous functional deifciency scale (r = –0.737,P = 0.010). Our ifndings can objectively identify the functional abnormality in some brain regions of ischemic stroke patients.

  18. Mapping the brain in type II diabetes: Voxel-based morphometry using DARTEL

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhiye [Department of Radiology, PLA General Hospital, 28 Fuxing Road, Beijing 100853 (China); Li, Lin [Department of Geriatric Endocrinology, PLA General Hospital, Beijing 100853 (China); Sun, Jie [Department of Endocrinology, PLA General Hospital, Beijing 100853 (China); Ma, Lin, E-mail: cjr.malin@vip.163.com [Department of Radiology, PLA General Hospital, 28 Fuxing Road, Beijing 100853 (China)

    2012-08-15

    Purpose: To investigate the pattern of brain volume changes of the brain in patients with type II diabetes mellitus using voxel-based morphometry. Material and methods: Institutional ethics approval and informed consent were obtained. VBM based on the high resolution three-dimensional T1-weighted fast spoiled gradient recalled echo MRI images was obtained from 16 type II diabetes patients (mean age 61.2 years) and 16 normal controls (mean age 59.6 years). All images were spatially preprocessed using Diffeomorphic Anatomical Registration using Exponentiated Lie algebra (DARTEL) algorithm, and the DARTEL templates were made from 100 normal subjects. Statistical parametric mapping was generated using analysis of covariance (ANCOVA). Results: An atrophy pattern of gray matter was seen in type II diabetes patients compared with controls that involved the right superior, middle, and inferior temporal gyri, right precentral gyrus, and left rolandic operculum region. The loss of white matter volume in type II diabetes mellitus was observed in right temporal lobe and left inferior frontal triangle region. ROI analysis revealed that the gray and white matter volume of right temporal lobe were significant lower in type II diabetes mellitus than that in controls (P < 0.05). Conclusion: This work demonstrated that type II diabetes mellitus patients mainly exhibited gray and white matter atrophy in right temporal lobe, and this finding supported that type II diabetes mellitus could lead to subtle diabetic brain structural changes in patients without dementia or macrovascular complications.

  19. Assessing residential exposure to urban noise using environmental models: does the size of the local living neighborhood matter?

    Science.gov (United States)

    Tenailleau, Quentin M; Bernard, Nadine; Pujol, Sophie; Houot, Hélène; Joly, Daniel; Mauny, Frédéric

    2015-01-01

    Environmental epidemiological studies rely on the quantification of the exposure level in a surface defined as the subject's exposure area. For residential exposure, this area is often the subject's neighborhood. However, the variability of the size and nature of the neighborhoods makes comparison of the findings across studies difficult. This article examines the impact of the neighborhood's definition on environmental noise exposure levels obtained from four commonly used sampling techniques: address point, façade, buffers, and official zoning. A high-definition noise model, built on a middle-sized French city, has been used to estimate LAeq,24 h exposure in the vicinity of 10,825 residential buildings. Twelve noise exposure indicators have been used to assess inhabitants' exposure. Influence of urban environmental factors was analyzed using multilevel modeling. When the sampled area increases, the average exposure increases (+3.9 dB), whereas the SD decreases (-1.6 dB) (P<0.01). Most of the indicators differ statistically. When comparing indicators from the 50-m and 400-m radius buffers, the assigned LAeq,24 h level varies across buildings from -9.4 to +22.3 dB. This variation is influenced by urban environmental characteristics (P<0.01). On the basis of this study's findings, sampling technique, neighborhood size, and environmental composition should be carefully considered in further exposure studies.

  20. Cerebral morphology and dopamine D2/D3 receptor distribution in humans: a combined [18F]fallypride and voxel-based morphometry study.

    Science.gov (United States)

    Woodward, Neil D; Zald, David H; Ding, Zhaohua; Riccardi, Patrizia; Ansari, M Sib; Baldwin, Ronald M; Cowan, Ronald L; Li, Rui; Kessler, Robert M

    2009-05-15

    The relationship between cerebral morphology and the expression of dopamine receptors has not been extensively studied in humans. Elucidation of such relationships may have important methodological implications for clinical studies of dopamine receptor ligand binding differences between control and patient groups. The association between cerebral morphology and dopamine receptor distribution was examined in 45 healthy subjects who completed T1-weighted structural MRI and PET scanning with the D(2)/D(3) ligand [(18)F]fallypride. Optimized voxel-based morphometry was used to create grey matter volume and density images. Grey matter volume and density images were correlated with binding potential (BP(ND)) images on a voxel-by-voxel basis using the Biological Parametric Mapping toolbox. Associations between cerebral morphology and BP(ND) were also examined for selected regions-of-interest (ROIs) after spatial normalization. Voxel-wise analyses indicated that grey matter volume and density positively correlated with BP(ND) throughout the midbrain, including the substantia nigra. Positive correlations were observed in medial cortical areas, including anterior cingulate and medial prefrontal cortex, and circumscribed regions of the temporal, frontal, and parietal lobes. ROI analyses revealed significant positive correlations between BP(ND) and cerebral morphology in the caudate, thalamus, and amygdala. Few negative correlations between morphology and BP(ND) were observed. Overall, grey matter density appeared more strongly correlated with BP(ND) than grey matter volume. Cerebral morphology, particularly grey matter density, correlates with [(18)F]fallypride BP(ND) in a regionally specific manner. Clinical studies comparing dopamine receptor availability between clinical and control groups may benefit by accounting for potential differences in cerebral morphology that exist even after spatial normalization.

  1. Comparing the Effect of Different Voxel Resolutions for Assessment of Vertical Root Fracture of Permanent Teeth

    Directory of Open Access Journals (Sweden)

    Uzun

    2015-07-01

    Full Text Available Background The teeth with undiagnosed vertical root fractures (VRFs are likely to receive endodontic treatment or retreatment, leading to frustration and inappropriate endodontic therapies. Moreover, many cases of VRFs cannot be diagnosed definitively until the extraction of tooth. Objectives This study aimed to assess the use of different voxel resolutions of two different cone beam computerized tomography (CBCT units in the detection VRFs in vitro. Materials and Methods The study material comprised 74 extracted human mandibular single rooted premolar teeth without root fractures that had not undergone any root-canal treatment. Images were obtained by two different CBCT units. Four image sets were obtained as follows: 1 3D Accuitomo 170, 4 × 4 cm field of view (FOV (0.080 mm3; 2 3D Accuitomo 170. 6 × 6 cm FOV (0.125 mm3; 3 NewTom 3G, 6˝ (0.16 mm3 and 4 NewTom 3G, 9˝ FOV (0.25 mm3. Kappa coefficients were calculated to assess both intra- and inter-observer agreements for each image set. Results No significant differences were found among observers or voxel sizes, with high average Z (Az results being reported for all groups. Both intra- and inter-observer agreement values were relatively better for 3D Accuitomo 170 images than the images from NewTom 3G. The highest Az and kappa values were obtained with 3D Accuitomo 170, 4 × 4 cm FOV (0.080 mm3 images. Conclusion No significant differences were found among observers or voxel sizes, with high Az results reported for all groups.

  2. The brain structure correlates of individual differences in trait mindfulness: a voxel-based morphometry study.

    Science.gov (United States)

    Lu, H; Song, Y; Xu, M; Wang, X; Li, X; Liu, J

    2014-07-11

    Mindfulness is the state of being attentive to and aware of what is taking place in the present, which is beneficial for reducing stress-related symptoms and improving mental and physical health. Previous studies have demonstrated that meditation practice can improve individuals' mindfulness through modifying functions and structures of multiple brain regions, including the anterior cingulate cortex (ACC), insula, fronto-limbic network, posterior cingulate cortex (PCC), and temporal-parietal junction. However, little is known about the neuroanatomical correlates of trait mindfulness. In the current study, we used voxel-based morphometry to investigate the neural correlates of individual differences in trait mindfulness by correlating the gray matter (GM) volume of each voxel across the whole brain with trait mindfulness measured by the Mindful Attention Awareness Scale in a large sample of young adults (N=247). We found that individuals who were more mindful of the present had greater GM volume in the right hippocampus/amygdala and bilateral ACC, but less GM volume in bilateral PCC and the left orbitofrontal cortex. These results suggest that trait mindfulness is associated with brain regions involved in executive attention, emotion regulation, and self-referential processing, through which mindfulness may exert its beneficial effects on psychological and physical well-being.

  3. Mechanism of natural organic matter removal by polyaluminum chloride: effect of coagulant particle size and hydrolysis kinetics.

    Science.gov (United States)

    Yan, Mingquan; Wang, Dongsheng; Ni, Jinren; Qu, Jiuhui; Chow, Christopher W K; Liu, Hailong

    2008-07-01

    The mechanism of natural organic matter (NOM) removal by AlCl(3) and polyaluminum chloride (PACl) was investigated through bench-scale tests. The fraction distributions of NOM and residual Al after coagulation in solution, colloid and sediment were analyzed as changes of coagulant dosage and pH. The influence of NOM, coagulant dose and pH on coagulation kinetics of AlCl(3) was investigated using photometric dispersion analyzer compared with PACl. Monomeric Al species (Al(a)) shows high ability to satisfy some unsaturated coordinate bonds of NOM to facilitate particle and NOM removal, while most of the flocs formed by Al(a) are small and difficult to settle. Medium polymerized Al species (Al(b)) can destabilize particle and NOM efficiently, while some flocs formed by Al(b) are not large and not easy to precipitate as compared to those formed by colloidal or solid Al species (Al(c)). Thus, Al(c) could adsorb and remove NOM efficiently. The removal of contaminant by species of Al(a), Al(b) and Al(c) follows mechanisms of complexation, neutralization and adsorption, respectively. Unlike preformed Al(b) in PACl, in-situ-formed Al(b) can remove NOM and particle more efficiently via the mechanism of further hydrolysis and transfer into Al(c) during coagulation. While the presence of NOM would reduce Al(b) formed in-situ due to the complexation of NOM and Al(a).

  4. The sizes of mini-voids in the local universe: an argument in favor of a warm dark matter model?

    CERN Document Server

    Tikhonov, A V; Yepes, G; Hoffman, Y

    2009-01-01

    Using high-resolution simulations within the Cold and Warm Dark Matter models we study the evolution of small scale structure in the Local Volume, a sphere of 8 Mpc radius around the Local Group. We compare the observed spectrum of mini-voids in the Local Volume with the spectrum of mini-voids determined from the simulations. We show that the \\LWDM model can easily explain both the observed spectrum of mini-voids and the presence of low-mass galaxies observed in the Local Volume, provided that all haloes with circular velocities greater than 20 km/s host galaxies. On the contrary within the \\LCDM model the distribution of the simulated mini-voids reflects the observed one if haloes with maximal circular velocities larger than $35 \\kms$ host galaxies. This assumption is in contradiction with observations of galaxies with circular velocities as low as 20 km/s in our Local Universe. A potential problem of the \\LWDM model could be the late formation of the haloes in which the gas can be efficiently photo-evaporat...

  5. Association between arsenic and different-sized dissolved organic matter in the groundwater of black-foot disease area, Taiwan.

    Science.gov (United States)

    Chen, Ting-Chien; Hseu, Zeng-Yei; Jean, Jiin-Shuh; Chou, Mon-Lin

    2016-09-01

    The formation of an arsenic (As)-dissolved organic matter (DOM) complex is important in driving the release of arsenic in groundwater. This study collected groundwater samples from a 20 m deep well throughout 2014 and separated each into three subsamples by ultrafiltration: high molecular weight-DOM (HDOM, 0.45 μm-10 kDa), medium molecular weight-DOM (MDOM, 10-1 kDa), and low molecular weight-DOM (LDOM, arsenic and the fractional DOM. Based on the EEM records, three fluorescence indicators were further calculated to characterize the DOM sources, including the fluorescence index (FI), the biological index (BI), and the humification index (HI). The experimental results indicated that arsenic in the groundwater was mainly partitioned into the MDOM and LDOM fractions. All fractional DOMs contained humic acid-like substances and were considered as microbial sources. LDOM had the highest humification degree and aromaticity, followed by MDOM and HDOM. The As and DOM association could be formed by a Fe-bridge, which was demonstrated by the Ks values and fourier transform infrared (FTIR) spectra of the DOM. The formation of AsFe-DOM complex was only significant in the MDOM and LDOM.

  6. Do Size and Insecticide Treatment Matter? Evaluation of Different Nets against Phlebotomus argentipes, the Vector of Visceral Leishmaniasis in Nepal.

    Directory of Open Access Journals (Sweden)

    Murari Lal Das

    Full Text Available In the Indian subcontinent, Leishmania donovani, the parasite causing visceral leishmaniasis (VL is transmitted by the sand fly vector Phlebotomus argentipes. Long lasting insecticide treated nets (LN have been postulated as alternative or complement to Indoor Residual Spraying but there are few field studies evaluating the entomological efficacy of different nets against this vector. We conducted two crossover trials in a VL endemic area in Nepal to compare the barrier effect of (1 LN with different mesh sizes (156 holes/inch2 vs 625 holes/inch2 and (2 alpha-cypermethrin treated LN and untreated nets having the same mesh size (156 holes/inch2. Each crossover trial had two arms consisting of a sequence of two different nets for 8 nights. We used 10 cattle sheds per trial. A cow placed under the net was used as bait. CDC light traps placed inside the nets were used to evaluate the number of P. argentipes crossing the net barrier. Negative binomial generalized estimating equation (GEE population-averaged models adjusted by night and sequence were used to estimate the barrier effect of the different nets. The crossover trials conducted in a rural village in Morang district (South-eastern Nepal demonstrated that reducing the size of the holes in treated nets (625 holes/inch2 increased the barrier effect of LN by 77% (95% confidence interval (CI: 56%-88% compared with treated nets with larger holes (156 holes/inch2. Treating nets with alpha-cypermethrin reduced the number of P. argentipes captured inside the nets by 77% (95% CI: 27%-93% compared with untreated nets. The effectiveness and acceptability of finer mesh pyrethroid treated LN should be tested for VL prevention in a randomized controlled trial.

  7. Do Size and Insecticide Treatment Matter? Evaluation of Different Nets against Phlebotomus argentipes, the Vector of Visceral Leishmaniasis in Nepal

    Science.gov (United States)

    Das, Murari Lal; Rowland, Mark; Austin, James W.; De Lazzari, Elisa; Picado, Albert

    2014-01-01

    In the Indian subcontinent, Leishmania donovani, the parasite causing visceral leishmaniasis (VL) is transmitted by the sand fly vector Phlebotomus argentipes. Long lasting insecticide treated nets (LN) have been postulated as alternative or complement to Indoor Residual Spraying but there are few field studies evaluating the entomological efficacy of different nets against this vector. We conducted two crossover trials in a VL endemic area in Nepal to compare the barrier effect of (1) LN with different mesh sizes (156 holes/inch2 vs 625 holes/inch2) and (2) alpha-cypermethrin treated LN and untreated nets having the same mesh size (156 holes/inch2). Each crossover trial had two arms consisting of a sequence of two different nets for 8 nights. We used 10 cattle sheds per trial. A cow placed under the net was used as bait. CDC light traps placed inside the nets were used to evaluate the number of P. argentipes crossing the net barrier. Negative binomial generalized estimating equation (GEE) population-averaged models adjusted by night and sequence were used to estimate the barrier effect of the different nets. The crossover trials conducted in a rural village in Morang district (South-eastern Nepal) demonstrated that reducing the size of the holes in treated nets (625 holes/inch2) increased the barrier effect of LN by 77% (95% confidence interval (CI): 56%–88%) compared with treated nets with larger holes (156 holes/inch2). Treating nets with alpha-cypermethrin reduced the number of P. argentipes captured inside the nets by 77% (95% CI: 27%–93%) compared with untreated nets. The effectiveness and acceptability of finer mesh pyrethroid treated LN should be tested for VL prevention in a randomized controlled trial. PMID:25494099

  8. An Improved Optimization Method for the Relevance Voxel Machine

    DEFF Research Database (Denmark)

    Ganz, Melanie; Sabuncu, M. R.; Van Leemput, Koen

    2013-01-01

    In this paper, we will re-visit the Relevance Voxel Machine (RVoxM), a recently developed sparse Bayesian framework used for predicting biological markers, e.g., presence of disease, from high-dimensional image data, e.g., brain MRI volumes. The proposed improvement, called IRVoxM, mitigates the ...

  9. Robust Segmentation of Voxel Shapes using Medial Surfaces

    NARCIS (Netherlands)

    Reniers, Dennie; Telea, Alexandru

    2008-01-01

    We present a new patch-type segmentation method for 3D voxel shapes based on the medial surface, also called surface skeleton. The boundaries of the simplified fore- and background skeletons map one-to-one to increasingly fuzzy, soft convex, respectively concave, edges of the shape. Using this prope

  10. Vessel-guided airway segmentation based on voxel classification

    DEFF Research Database (Denmark)

    Lo, Pechin Chien Pau; Sporring, Jon; Ashraf, Haseem;

    2008-01-01

    This paper presents a method for improving airway tree segmentation using vessel orientation information. We use the fact that an airway branch is always accompanied by an artery, with both structures having similar orientations. This work is based on a  voxel classification airway segmentation...

  11. Finding significantly connected voxels based on histograms of connection strengths

    DEFF Research Database (Denmark)

    Kasenburg, Niklas; Pedersen, Morten Vester; Darkner, Sune

    2016-01-01

    -distribution and significance is determined using the false discovery rate (FDR). Segmentations are based on significantly connected voxels and their FDR. In this work we focus on the thalamus and the target regions were chosen by dividing the cortex into a prefrontal/temporal zone, motor zone, somatosensory zone and a parieto...

  12. Quality control of geological voxel models using experts' gaze

    NARCIS (Netherlands)

    Maanen, van Peter-Paul; Busschers, Freek S.; Brouwer, Anne-Marie; Meulendijk, van der Michiel J.; Erp, van Jan B.F.

    2015-01-01

    Due to an expected increase in geological voxel model data-flow and user demands, the development of improved quality control for such models is crucial. This study explores the potential of a new type of quality control that improves the detection of errors by just using gaze behavior of 12 geologi

  13. Motion-Compensated Compression of Dynamic Voxelized Point Clouds.

    Science.gov (United States)

    De Queiroz, Ricardo L; Chou, Philip A

    2017-05-24

    Dynamic point clouds are a potential new frontier in visual communication systems. A few articles have addressed the compression of point clouds, but very few references exist on exploring temporal redundancies. This paper presents a novel motion-compensated approach to encoding dynamic voxelized point clouds at low bit rates. A simple coder breaks the voxelized point cloud at each frame into blocks of voxels. Each block is either encoded in intra-frame mode or is replaced by a motion-compensated version of a block in the previous frame. The decision is optimized in a rate-distortion sense. In this way, both the geometry and the color are encoded with distortion, allowing for reduced bit-rates. In-loop filtering is employed to minimize compression artifacts caused by distortion in the geometry information. Simulations reveal that this simple motion compensated coder can efficiently extend the compression range of dynamic voxelized point clouds to rates below what intra-frame coding alone can accommodate, trading rate for geometry accuracy.

  14. Voxel model in BNCT treatment planning: performance analysis and improvements

    Science.gov (United States)

    González, Sara J.; Carando, Daniel G.; Santa Cruz, Gustavo A.; Zamenhof, Robert G.

    2005-02-01

    In recent years, many efforts have been made to study the performance of treatment planning systems in deriving an accurate dosimetry of the complex radiation fields involved in boron neutron capture therapy (BNCT). The computational model of the patient's anatomy is one of the main factors involved in this subject. This work presents a detailed analysis of the performance of the 1 cm based voxel reconstruction approach. First, a new and improved material assignment algorithm implemented in NCTPlan treatment planning system for BNCT is described. Based on previous works, the performances of the 1 cm based voxel methods used in the MacNCTPlan and NCTPlan treatment planning systems are compared by standard simulation tests. In addition, the NCTPlan voxel model is benchmarked against in-phantom physical dosimetry of the RA-6 reactor of Argentina. This investigation shows the 1 cm resolution to be accurate enough for all reported tests, even in the extreme cases such as a parallelepiped phantom irradiated through one of its sharp edges. This accuracy can be degraded at very shallow depths in which, to improve the estimates, the anatomy images need to be positioned in a suitable way. Rules for this positioning are presented. The skin is considered one of the organs at risk in all BNCT treatments and, in the particular case of cutaneous melanoma of extremities, limits the delivered dose to the patient. Therefore, the performance of the voxel technique is deeply analysed in these shallow regions. A theoretical analysis is carried out to assess the distortion caused by homogenization and material percentage rounding processes. Then, a new strategy for the treatment of surface voxels is proposed and tested using two different irradiation problems. For a parallelepiped phantom perpendicularly irradiated with a 5 keV neutron source, the large thermal neutron fluence deviation present at shallow depths (from 54% at 0 mm depth to 5% at 4 mm depth) is reduced to 2% on average

  15. Probing the Dark Matter Radial Profile in Lens Galaxies and the Size of X-Ray Emitting Region in Quasars with Microlensing

    Science.gov (United States)

    Jiménez-Vicente, J.; Mediavilla, E.; Kochanek, C. S.; Muñoz, J. A.

    2015-06-01

    We use X-ray and optical microlensing measurements to study the shape of the dark matter density profile in the lens galaxies and the size of the (soft) X-ray emission region. We show that single epoch X-ray microlensing is sensitive to the source size. Our results, in good agreement with previous estimates, show that the size of the X-ray emission region scales roughly linearly with the black hole mass, with a half-light radius of {{R}}1/2≃ (24+/- 14){{r}}{\\boldsymbol{g}} where {r}g={{GM}}{BH}/{c}2. This corresponds to a size of {log}({{R}}1/2/{cm})={15.6}-0.3+0.3 or ˜1 lt-day for a black hole mass of {M}{BH}={10}9 {M}⊙ . We simultaneously estimated the fraction of the local surface mass density in stars, finding that the stellar mass fraction is α = 0.20 ± 0.05 at an average radius of ˜ 1.9{R}e, where Re is the effective radius of the lens. This stellar mass fraction is insensitive to the X-ray source size and in excellent agreement with our earlier results based on optical data. By combining X-ray and optical microlensing data, we can divide this larger sample into two radial bins. We find that the surface mass density in the form of stars is α = 0.31 ± 0.15 and α = 0.13 ± 0.05 at (1.3+/- 0.3){R}e and (2.3+/- 0.3){R}e, respectively, in good agreement with expectations and some previous results.

  16. The role of the interface in germanium quantum dots: when not only size matters for quantum confinement effects.

    Science.gov (United States)

    Cosentino, S; Mio, A M; Barbagiovanni, E G; Raciti, R; Bahariqushchi, R; Miritello, M; Nicotra, G; Aydinli, A; Spinella, C; Terrasi, A; Mirabella, S

    2015-07-14

    Quantum confinement (QC) typically assumes a sharp interface between a nanostructure and its environment, leading to an abrupt change in the potential for confined electrons and holes. When the interface is not ideally sharp and clean, significant deviations from the QC rule appear and other parameters beyond the nanostructure size play a considerable role. In this work we elucidate the role of the interface on QC in Ge quantum dots (QDs) synthesized by rf-magnetron sputtering or plasma enhanced chemical vapor deposition (PECVD). Through a detailed electron energy loss spectroscopy (EELS) analysis we investigated the structural and chemical properties of QD interfaces. PECVD QDs exhibit a sharper interface compared to sputter ones, which also evidences a larger contribution of mixed Ge-oxide states. Such a difference strongly modifies the QC strength, as experimentally verified by light absorption spectroscopy. A large size-tuning of the optical bandgap and an increase in the oscillator strength occur when the interface is sharp. A spatially dependent effective mass (SPDEM) model is employed to account for the interface difference between Ge QDs, pointing out a larger reduction in the exciton effective mass in the sharper interface case. These results add new insights into the role of interfaces on confined systems, and open the route for reliable exploitation of QC effects.

  17. When size matters: differences in demineralized bone matrix particles affect collagen structure, mesenchymal stem cell behavior, and osteogenic potential.

    Science.gov (United States)

    Dozza, B; Lesci, I G; Duchi, S; Della Bella, E; Martini, L; Salamanna, F; Falconi, M; Cinotti, S; Fini, M; Lucarelli, E; Donati, D

    2017-04-01

    Demineralized bone matrix (DBM) is a natural, collagen-based, osteoinductive biomaterial. Nevertheless, there are conflicting reports on the efficacy of this product. The purpose of this study was to evaluate whether DBM collagen structure is affected by particle size and can influence DBM cytocompatibility and osteoinductivity. Sheep cortical bone was ground and particles were divided in three fractions with different sizes, defined as large (L, 1-2 mm), medium (M, 0.5-1 mm), and small (S, structure, with DBM-M being altered but not as much as DBM-S. DBM-M displayed a preferable trend in almost all biological characteristics tested, although all DBM particles revealed an optimal cytocompatibility. Subcutaneous implantation of DBM particles into immunocompromised mice resulted in bone induction only for DBM-M. When sheep MSC were seeded onto particles before implantation, all DBM particles were able to induce new bone formation with the best incidence for DBM-M and DBM-S. In conclusion, the collagen alteration in DBM-M is likely the best condition to promote bone induction in vivo. Furthermore, the choice of 0.5-1 mm particles may enable to obtain more efficient and consistent results among different research groups in bone tissue-engineering applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1019-1033, 2017.

  18. Proinflammatory and cytotoxic effects of Mexico City air pollution particulate matter in vitro are dependent on particle size and composition.

    Science.gov (United States)

    Osornio-Vargas, Alvaro R; Bonner, James C; Alfaro-Moreno, Ernesto; Martínez, Leticia; García-Cuellar, Claudia; Ponce-de-León Rosales, Sergio; Miranda, Javier; Rosas, Irma

    2003-08-01

    Exposure to urban airborne particulate matter (PM) is associated with adverse health effects. We previously reported that the cytotoxic and proinflammatory effects of Mexico City PM10 (less than or equal to 10 micro m mean aerodynamic diameter) are determined by transition metals and endotoxins associated with these particles. However, PM2.5 (less than or equal to 2.5 micro m mean aerodynamic diameter) could be more important as a human health risk because this smaller PM has the potential to reach the distal lung after inhalation. In this study, we compared the cytotoxic and proinflammatory effects of Mexico City PM10 with those of PM2.5 using the murine monocytic J774A.1 cell line in vitro. PMs were collected from the northern zone or the southeastern zone of Mexico City. Elemental composition and bacterial endotoxin on PMs were measured. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) production by J774A.1 cells was measured in the presence or absence of recombinant endotoxin-neutralizing protein (rENP). Both northern and southeastern PMs contained endotoxin and a variety of transition metals. Southeastern PM10 contained the highest endotoxin levels, 2-fold higher than that in northern PM10. Northern and southeastern PM2.5 contained the lowest endotoxin levels. Accordingly, southeastern PM10 was the most potent in causing secretion of the proinflammatory cytokines TNF-alpha and IL-6. All PM2.5 and PM10 samples caused cytotoxicity, but northern PMs were the most toxic. Cytokine secretion induced by southeastern PM10 was reduced 50-75% by rENP. These results indicate major differences in PM10 and PM2.5. PM2.5 induces cytotoxicity in vitro through an endotoxin-independent mechanism that is likely mediated by transition metals. In contrast, PM10 with relatively high levels of endotoxin induces proinflammatory cytokine release via an endotoxin-dependent mechanism.

  19. Particulate Matter in Second-Hand Smoke Emitted from Different Cigarette Sizes and Types of the Brand Vogue Mainly Smoked by Women

    Directory of Open Access Journals (Sweden)

    Nora Kant

    2016-08-01

    Full Text Available Indoor air pollution with harmful particulate matter (PM is mainly caused by cigarette smoke. Super-Slim-Size-Cigarettes (SSL are considered a less harmful alternative to King-Size-Cigarettes (KSC due to longer filters and relatively low contents. We ask if “Combined Mainstream and Sidestream Smoke” (CMSS-associated PM levels of SSL are lower than of KSC and thus are potentially less harmful. PM concentrations in CMSS (PM10, PM2.5, and PM1 are measured from four cigarette types of the brand Vogue, using an “automatic-environmental-tobacco-smoke-emitter” (AETSE and laser aerosol spectrometry: SSL-BLEUE, -MENTHE, -LILAS and KSC-La Cigarette and -3R4F reference. This analysis shows that SSL MENTHE emitted the highest amount of PM, and KSC-La Cigarette the lowest. 3R4F reference emitted PM in the middle range, exceeding SSL BLEUE and falling slightly below SSL LILAS. It emerged that PM1 constituted the biggest proportion of PM emission. The outcome shows significant type-specific differences for emitted PM concentrations. Our results indicate that SSL are potentially more harmful for passive smokers than the respective KSC. However, this study cannot give precise statements about the general influence of the size of a cigarette on PM. Alarming is that PM1 is responsible for the biggest proportion of PM pollution, since smaller particles cause more harmful effects.

  20. [Effects of particle-sizes, pH and organic matter on adsorption and desorption of mercury to sediments in the Songhua River].

    Science.gov (United States)

    Zhu, Hui; Yan, Bai-Xing; Zhang, Feng-Song; Lu, Yong-Zheng; Wang, Li-Xia

    2010-10-01

    The present study aims to further reveal the environmental behavior of mercury on sediments surface. Effects of particle-sizes, pH and concentrations of dissolved organic matter (DOM) on mercury adsorption and desorption to the surface of sediments in the Songhua River were investigated by simulation experiments. A distinct variety of absorption ability among sediments with different particle-sizes was observed. Under this experimental condition, the absorption ability increased inversely with particle-size of sediments. In all absorption systems, mercury adsorption was enhanced when pH increased from 3.5 to 4.5, while mercury adsorption was inhibited significantly with the increasing of pH when pH values were above 4.5. With the increasing of pH values, the desorption of mercury presented a decreasing-increasing trend, the minimum desorption occurred at pH 5. Citric acid inhibited the mercury adsorption, and the intensity was correlated with mercury concentrations. Effects of citric acid on desorption of mercury were also apparently. With the increasing of citric acid concentrations, its effect on desorption presented a trend as enhanced-inhibited-steadied. Therefore, the above factors affected the mercury adsorption and desorption obviously, and it was necessary to take these factors into consideration in conducting the rivers' mercury control and dealing with a sudden pollution incident.

  1. Particulate Matter in Second-Hand Smoke Emitted from Different Cigarette Sizes and Types of the Brand Vogue Mainly Smoked by Women.

    Science.gov (United States)

    Kant, Nora; Müller, Ruth; Braun, Markus; Gerber, Alexander; Groneberg, David

    2016-08-08

    Indoor air pollution with harmful particulate matter (PM) is mainly caused by cigarette smoke. Super-Slim-Size-Cigarettes (SSL) are considered a less harmful alternative to King-Size-Cigarettes (KSC) due to longer filters and relatively low contents. We ask if "Combined Mainstream and Sidestream Smoke" (CMSS)-associated PM levels of SSL are lower than of KSC and thus are potentially less harmful. PM concentrations in CMSS (PM10, PM2.5, and PM₁) are measured from four cigarette types of the brand Vogue, using an "automatic-environmental-tobacco-smoke-emitter" (AETSE) and laser aerosol spectrometry: SSL-BLEUE, -MENTHE, -LILAS and KSC-La Cigarette and -3R4F reference. This analysis shows that SSL MENTHE emitted the highest amount of PM, and KSC-La Cigarette the lowest. 3R4F reference emitted PM in the middle range, exceeding SSL BLEUE and falling slightly below SSL LILAS. It emerged that PM₁ constituted the biggest proportion of PM emission. The outcome shows significant type-specific differences for emitted PM concentrations. Our results indicate that SSL are potentially more harmful for passive smokers than the respective KSC. However, this study cannot give precise statements about the general influence of the size of a cigarette on PM. Alarming is that PM₁ is responsible for the biggest proportion of PM pollution, since smaller particles cause more harmful effects.

  2. Pyrogenic organic matter accumulation after density and particle size fractionation of burnt Cambisol using solid-state nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    López-Martín, María; Knicker, Heike

    2017-04-01

    Fires lead to formation of the pyrogenic organic matter (PyOM) which is quickly incorporated into the soil. The charring process involves chemical alterations of the litter material, where biologically available structures are transferred into aromatic polymers, such as black carbon (BC) and black nitrogen (BN). In order to reveal the medium term fate of BC and BN in soils, the top 5 cm of A horizons from unburnt, single and double burnt Cambisols of the Sierra de Aznalcóllar (Southern Spain) were collected 7 year after an intense fire and separated according to their density and their size (Golchin et al., 1994; Sohi et al., 2001). The density fractionation yielded in the free (fPOM), occluded particulate organic matter (oPOM) and the mineral-association organic fraction (MAF) and was performed using a sodium polytungstate solution with a density of 1.8 g cm-3. The MAF was further separated into the sand (2 mm to 63 μm) and coarse silt (63 to 20 μm) and fine fraction (competitividad de España (MINECO) and the European Regional Development Fund (ERDF) for financial support of the project (CGL2009-10557). The MINECO is also acknowledged for providing the Formación de Professional Investigator (FPI) grant (BES-2010-42581). REFERENCES Golchin, A., Oades, J., Skjemstad, J., Clarke, P., 1994. Soil structure and carbon cycling. Soil Research 32, 1043-1068. Sohi, S.P., Mahieu, N., Arah, J.R.M., Powlson, D.S., Madari, B., Gaunt, J.L., 2001. A procedure for isolating soil organic matter fractions suitable for modelling. Soil Science Society of America Journal 65, 1121.

  3. Differences in brain structure in patients with distinct sites of chronic pain A voxel-based morphometric analysis

    Institute of Scientific and Technical Information of China (English)

    Cuiping Mao; Longxiao Wei; Qiuli Zhang; Xia Liao; Xiaoli Yang; Ming Zhang

    2013-01-01

    A reduction in gray matter volume is common in patients with chronic back pain, and different types of pain are associated with gray matter abnormalities in distinct brain regions. To examine ences in brain morphology in patients with low back pain or neck and upper back pain, we gated changes in gray matter volume in chronic back pain patients having different sites of pain using voxel-based morphometry. A reduction in cortical gray matter volume was found primarily in the left postcentral gyrus and in the left precuneus and bilateral cuneal cortex of patients with low back pain. In these patients, there was an increase in subcortical gray matter volume in the bilateral putamen and accumbens, right pal idum, right caudate nucleus, and left amygdala. In upper back pain patients, reduced cortical gray matter volume was found in the left precentral and left tral cortices. Our findings suggest that regional gray matter volume abnormalities in low back pain patients are more extensive than in upper back pain patients. Subcortical gray matter volume in-creases are found only in patients with low back pain.

  4. Sex-related difference in human white matter volumes studied: Inspection of the corpus callosum and other white matter by VBM

    Science.gov (United States)

    Shiino, Akihiko; Chen, Yen-Wei; Tanigaki, Kenji; Yamada, Atsushi; Vigers, Piers; Watanabe, Toshiyuki; Tooyama, Ikuo; Akiguchi, Ichiro

    2017-01-01

    It has been contended that any observed difference of the corpus callosum (CC) size between men and women is not sex-related but brain-size-related. A recent report, however, showed that the midsagittal CC area was significantly larger in women in 37 brain-size-matched pairs of normal young adults. Since this constituted strong evidence of sexual dimorphism and was obtained from publicly available data in OASIS, we examined volume differences within the CC and in other white matter using voxel-based morphometry (VBM). We created a three-dimensional region of interest of the CC and measured its volume. The VBM statistics were analyzed by permutation test and threshold-free cluster enhancement (TFCE) with the significance levels at FWER sex-related difference. We also found that white matter in the bilateral anterior frontal regions and the left lateral white matter near to Broca’s area were larger in women, whereas there were no significant larger regions in men. Since we used brain-size-matched subjects, our results gave strong volumetric evidence of localized sexual dimorphism of white matter.

  5. [Determination of the distribution of relative molecular mass of organic matter by high pressure size exclusion chromatography with UV and TOC detectors].

    Science.gov (United States)

    Zhang, Han; Dong, Bing-Zhi

    2012-09-01

    An on-line high pressure size exclusion chromatography (HPSEC) with UV and TOC detectors was adapted to examine the distribution of relative molecular mass of natural organic matter (NOM). Through synchronous determination of UV254 and TOC responses in a wide range of relative molecular mass, it was possible to accurately characterize the structure of NOM, especially for some non-aromatic and non-conjugated double bond organics which have low response to UV. It was found that, TOC detector was capable of detecting all kinds of organic matters, including sucrose, sodium alginate and other hydrophilic organic compounds. The sample volume had a positively linear correlation with the TOC response, indicating that the larger volume would produce stronger responses. The effect of ion strength was relatively low, shown by the small decrease of peak area (1.2% ) from none to 0.2 mol x L(-1) NaCl. The pH value of tested samples should be adjusted to neutral or acidic because when the samples were alkaline, the results might be inaccurate. Compared to the sample solvents adopted as ultrapure water, the samples prepared by mobile phase solvents had less interference to salt boundary peak. The on-line HPSEC-UV-TOC can be used accurately to characterize the distribution of relative molecular mass and its four fractions in River Xiang.

  6. Size distributions and sources of elements in particulate matter at curbside,urban and rural sites in Beijing

    Institute of Scientific and Technical Information of China (English)

    Jingchun Duan; Jihua Tan; Shulan Wang; Jimin Hao; Fahe Chai

    2012-01-01

    Size distributions of 29 elements in aerosols collected at urban,rural and curbside sites in Beijing were studied.High levels of Mn,Ni,As,Cd and Pb indicate the pollution of toxic heavy metals cannot be neglected in Beijing.Principal component analysis (PCA)indicates 4 sources of combustion emission,crust related sources,traffic related sources and volatile species from coal combustion.The elements can be roughly divided into 3 groups by size distribution and enrichment factors method (EFs).Group 1 elements are crust related and mainly found within coarse mode including Al,Mg,Ca,Sc,Ti,Fe,Sr,Zr and Ba; Group 2 elements are fossil fuel related and mostly concentrated in accumulation mode including S,As,Se,Ag,Cd,T1 and Pb; Group 3 elements are multi-source related and show multi-mode distribution including Be,Na,K,Cr,Mn,Co,Ni,Cu,Zn,Ga,Mo,Sn and Sb.The EFs of Be,S,Cr,Co,Ni,Cu,Ga,Se,Mo,Ag,Cd,Sb,T1 and Pb show higher values in winter than in summer indicating sources of coal combustion for heating in winter.The abundance of Cu and Sb in coarse mode is about 2-6 times higher at curbside site than at urban site indicating their traffic sources.Coal burning may be the major source of Pb in Beijing since the phase out of leaded gasoline,as the EFs of Pb are comparable at both urban and curbside sites,and about two times higher in winter than that in summer.

  7. Size Matters a Lot: Drought-Affected Italian Oaks Are Smaller and Show Lower Growth Prior to Tree Death

    Science.gov (United States)

    Colangelo, Michele; Camarero, Jesús J.; Borghetti, Marco; Gazol, Antonio; Gentilesca, Tiziana; Ripullone, Francesco

    2017-01-01

    Hydraulic theory suggests that tall trees are at greater risk of drought-triggered death caused by hydraulic failure than small trees. In addition the drop in growth, observed in several tree species prior to death, is often interpreted as an early-warning signal of impending death. We test these hypotheses by comparing size, growth, and wood-anatomy patterns of living and now-dead trees in two Italian oak forests showing recent mortality episodes. The mortality probability of trees is modeled as a function of recent growth and tree size. Drift-diffusion-jump (DDJ) metrics are used to detect early-warning signals. We found that the tallest trees of the anisohydric Italian oak better survived drought contrary to what was predicted by the theory. Dead trees were characterized by a lower height and radial-growth trend than living trees in both study sites. The growth reduction of now-dead trees started about 10 years prior to their death and after two severe spring droughts during the early 2000s. This critical transition in growth was detected by DDJ metrics in the most affected site. Dead trees were also more sensitive to drought stress in this site indicating different susceptibility to water shortage between trees. Dead trees did not form earlywood vessels with smaller lumen diameter than surviving trees but tended to form wider latewood vessels with a higher percentage of vessel area. Since living and dead trees showed similar competition we did not expect that moderate thinning and a reduction in tree density would increase the short-term survival probability of trees. PMID:28270816

  8. Do manual and voxel-based morphometry measure the same? – A proof of concept study

    Directory of Open Access Journals (Sweden)

    Niels K. Focke

    2014-04-01

    Full Text Available Voxel-based morphometry (VBM is a commonly used method to study volumetric variations on a whole brain basis. However it is often criticised for potential confounds, mainly based on imperfect spatial registration. We therefore aimed to evaluate if VBM and gold-standard manual volumetry are measuring the same effects with respect to subcortical grey matter volumes. Manual regions-of-interest (ROIs were drawn in the hippocampus, amygdala, nucleus accumbens, thalamus, putamen, pallidum and caudate nucleus bilaterally. Resulting volumes were used for a whole brain VBM correlation analysis with SPM8. The hippocampus, amygdala, putamen and caudate nucleus were correctly identified by SPM using the contemporary high-dimensional normalization (DARTEL toolbox. This strongly suggests that VBM and manual volumetry both are indeed measuring the same effects with regard to subcortical brain structures.

  9. Brain structure in diving players on MR imaging studied with voxel-based morphometry

    Institute of Scientific and Technical Information of China (English)

    Gaoxia Wei; Jing Luo; Youfa Li

    2009-01-01

    We adopted professional diving players as a typical subject pool to explore whether structural brain differences relative to motor skill acquisition exist between highly skilled athletes and non-athletes. Based on the voxel-based morphometric (VBM) technique, structural MRIs of the brains of 12 elite diving players with professional training were analyzed and compared with those of control subjects with-out any professional physical training. Diving players showed significantly increased gray matter density in the thalamus and left pre-central gyrus than control subjects. However, future researches are needed to prove the contribution of preposition and practice. It also suggests that athletes as the subject pool could form a new subject pool to explore plastic change induced by motor skill acquisition.

  10. Mechanisms underlying fatigue: a voxel-based morphometric study of chronic fatigue syndrome

    Directory of Open Access Journals (Sweden)

    Watanabe Yasuyoshi

    2004-10-01

    Full Text Available Abstract Background Fatigue is a crucial sensation that triggers rest, yet its underlying neuronal mechanisms remain unclear. Intense long-term fatigue is a symptom of chronic fatigue syndrome, which is used as a model to study the mechanisms underlying fatigue. Methods Using magnetic resonance imaging, we conducted voxel-based morphometry of 16 patients and 49 age-matched healthy control subjects. Results We found that patients with chronic fatigue syndrome had reduced gray-matter volume in the bilateral prefrontal cortex. Within these areas, the volume reduction in the right prefrontal cortex paralleled the severity of the fatigue of the subjects. Conclusion These results are consistent with previous reports of an abnormal distribution of acetyl-L-carnitine uptake, which is one of the biochemical markers of chronic fatigue syndrome, in the prefrontal cortex. Thus, the prefrontal cortex might be an important element of the neural system that regulates sensations of fatigue.

  11. Voxel-based analysis of fractional anisotropy in post-stroke apathy.

    Directory of Open Access Journals (Sweden)

    Song-ran Yang

    Full Text Available To explore the structural basis of post-stroke apathy by using voxel-based analysis (VBA of fractional anisotropy (FA maps.We enrolled 54 consecutive patients with ischemic stroke during convalescence, and divided them into apathy (n = 31 and non-apathy (n = 23 groups. We obtained magnetic resonance images of their brains, including T1, T2 and DTI sequences. Age, sex, education level, Hamilton Depression Scale (HAMD scores, Mini-Mental State Examination (MMSE scores, National Institutes of Health Stroke Scale (NIHSS scores, and infarct locations for the two groups were compared. Finally, to investigate the structural basis of post-stroke apathy, VBA of FA maps was performed in which we included the variables that a univariate analysis determined had P-values less than 0.20 as covariates.HAMD (P = 0.01 and MMSE (P<0.01 scores differed significantly between the apathy and non-apathy groups. After controlling for age, education level, HAMD scores, and MMSE scores, significant FA reduction was detected in four clusters with peak voxels at the genu of the corpus callosum (X = -16, Y = 30, Z = 8, left anterior corona radiata (-22, 30, 10, splenium of the corpus callosum (-24, -56, 18, and right inferior frontal gyrus white matter (52, 24, 18, after family-wise error correction for multiple comparisons.Post-stroke apathy is related to depression and cognitive decline. Damage to the genu of the corpus callosum, left anterior corona radiata, splenium of the corpus callosum, and white matter in the right inferior frontal gyrus may lead to apathy after ischemic stroke.

  12. Larger right posterior parietal volume in action video game experts: a behavioral and voxel-based morphometry (VBM) study.

    Science.gov (United States)

    Tanaka, Satoshi; Ikeda, Hanako; Kasahara, Kazumi; Kato, Ryo; Tsubomi, Hiroyuki; Sugawara, Sho K; Mori, Makoto; Hanakawa, Takashi; Sadato, Norihiro; Honda, Manabu; Watanabe, Katsumi

    2013-01-01

    Recent studies suggest that action video game players exhibit superior performance in visuospatial cognitive tasks compared with non-game players. However, the neural basis underlying this visuospatial cognitive performance advantage remains largely unknown. The present human behavioral and imaging study compared gray matter volume in action video game experts and non-experts using structural magnetic resonance imaging and voxel-based morphometry analysis. The results revealed significantly larger gray matter volume in the right posterior parietal cortex in experts compared with non-experts. Furthermore, the larger gray matter volume in the right posterior parietal cortex significantly correlated with individual performance in a visual working memory task in experts. These results suggest that differences in brain structure may be linked to extensive video game play, leading to superior visuospatial cognitive performance in action video game experts.

  13. Toxicity of benz(a)anthracene and fluoranthene to marine phytoplankton in culture: Does cell size really matter?

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Hiba Ben [UMR 5119 ECOSYM, CNRS-IRD-Universite Montpellier II-Ifremer-Universite Montpellier I, SMEL 2 rue des Chantiers, F-34200 Sete (France); Laboratoire de Cytologie Vegetale et Phytoplanctonologie, Faculte des Sciences de Bizerte, Universite de Carthage, Zarzouna 7021, Bizerte (Tunisia); Leboulanger, Christophe, E-mail: christophe.leboulanger@ird.fr [UMR 5119 ECOSYM, CNRS-IRD-Universite Montpellier II-Ifremer-Universite Montpellier I, SMEL 2 rue des Chantiers, F-34200 Sete (France); Le Floc' h, Emilie [UMS MEDIMEER, CNRS-Universite Montpellier II, SMEL 2 rue des Chantiers F-34200 Sete (France); Hadj Mabrouk, Hassine; Sakka Hlaili, Asma [Laboratoire de Cytologie Vegetale et Phytoplanctonologie, Faculte des Sciences de Bizerte, Universite de Carthage, Zarzouna 7021, Bizerte (Tunisia)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Polycyclic aromatic hydrocarbons (PAHs) in the marine environment are a hazardous chemical legacy. Black-Right-Pointing-Pointer Benz(a)anthracene and fluoranthene are toxic to phytoplankton photosynthesis and growth in culture. Black-Right-Pointing-Pointer Acute (photosynthesis) and chronic (population growth) effects have different thresholds. Black-Right-Pointing-Pointer Toxicity depends on both the species selected as a model and the compound considered. Black-Right-Pointing-Pointer Further study of the size/sensitivity relationship is required to draw more general conclusions. - Abstract: The toxicity of benz(a)anthracene and fluoranthene (polycyclic aromatic hydrocarbons, PAHs) was evaluated on seven species of marine algae in culture belonging to pico-, nano-, and microphytoplankton, exposed to increasing concentrations of up to 2 mg L{sup -1}. The short-term (24 h) toxicity was assessed using chlorophyll a fluorescence transients, linked to photosynthetic parameters. The maximum quantum yield Fv/Fm was lower at the highest concentrations tested and the toxicity thresholds were species-dependent. For acute effects, fluoranthene was more toxic than benz(a)anthracene, with LOECs of 50.6 and 186 {mu}g L{sup -1}, respectively. After 72 h exposure, there was a dose-dependent decrease in cell density, fluoranthene being more toxic than benz(a)anthracene. The population endpoint at 72 h was affected to a greater extent than the photosynthetic endpoint at 24 h. EC50 was evaluated using the Hill model, and species sensitivity was negatively correlated to cell biovolume. The largest species tested, the dinoflagellate Alexandrium catenella, was almost insensitive to either PAH. The population endpoint EC50s for fluoranthene varied from 54 {mu}g L{sup -1} for the picophytoplankton Picochlorum sp. to 418 {mu}g L{sup -1} for the larger diatom Chaetoceros muelleri. The size/sensitivity