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1

Normal variation in fronto-occipital circuitry and cerebellar structure with an autism-associated polymorphism of CNTNAP2  

PubMed Central

Recent genetic studies have implicated a number of candidate genes in the pathogenesis of Autism Spectrum Disorder (ASD). Polymorphisms of CNTNAP2 (contactin-associated like protein-2), a member of the neurexin family, have already been implicated as a susceptibility gene for autism by at least 3 separate studies. We investigated variation in white and grey matter morphology using structural MRI and diffusion tensor imaging. We compared volumetric differences in white and grey matter and fractional anisotropy values in control subjects characterised by genotype at rs7794745, a single nucleotide polymorphism in CNTNAP2. Homozygotes for the risk allele showed significant reductions in grey and white matter volume and fractional anisotropy in several regions that have already been implicated in ASD, including the cerebellum, fusiform gyrus, occipital and frontal cortices. Male homozygotes for the risk alleles showed greater reductions in grey matter in the right frontal pole and in FA in the right rostral fronto-occipital fasciculus compared to their female counterparts who showed greater reductions in FA of the anterior thalamic radiation. Thus a risk allele for autism results in significant cerebral morphological variation, despite the absence of overt symptoms or behavioural abnormalities. The results are consistent with accumulating evidence of CNTNAP2's function in neuronal development. The finding suggests the possibility that the heterogeneous manifestations of ASD can be aetiologically characterised into distinct subtypes through genetic-morphological analysis.

Tan, Geoffrey C.Y.; Doke, Thomas F.; Ashburner, John; Wood, Nicholas W.; Frackowiak, Richard S.J.

2010-01-01

2

The "frontal syndrome" revisited: lessons from electrostimulation mapping studies.  

PubMed

For a long time, in a localizationist view of brain functioning, a combination of symptoms called "frontal syndrome" has been interpreted as the direct result of damages involving the frontal lobe(s). The goal of this review is to challenge this view, that is, to move to a hodotopical approach to lesion mapping, on the basis of new insights provided by intraoperative electrostimulation mapping investigations in patients who underwent awake surgery for cerebral tumors. These original data reported in the last decade break with the traditional dogma of a modular and fixed organization of the central nervous system, by switching to the concepts of cerebral connectivity and plasticity - i.e., a brain organization based on dynamic interrelationships between parallel distributed networks. According to this revisited model, "frontal symptoms" can be generated by tumor or electrostimulation not only of the frontal lobes, but also of cortical and subcortical (white matter pathways/deep gray nuclei) structures outside the frontal lobes: especially, stimulation of the superior longitudinal fascicle may elicit speech production disorders, syntactic disturbances, involuntary language switching or phonemic paraphasia (arcuate fascicle), stimulation of the inferior fronto-occipital fascicle can generate semantic paraphasia or deficit of cross-modal judgment, stimulation of the subcallosal fasciculus may elicit transcortical motor aphasia, while stimulation of the striatum induces preservations. On the other hand, it is also possible to perform extensive right or left frontal lobectomy in patients who continue to have a normal familial, social and professional life, without "frontal syndrome". Therefore, this provocative approach may open the door to a renewal in the modeling of brain processing as well as in its clinical applications, especially in the fields of cerebral surgery and functional rehabilitation. These findings illustrate well the need to reinforce links between cognitive neuroscience and clinical neurology/neurosurgery. PMID:21621762

Duffau, Hugues

2011-05-07

3

Tractography of the uncinate fasciculus and the posterior cingulate fasciculus in patients with mild cognitive impairment and Alzheimer disease.  

PubMed

INTRODUCTION: Brain tractography is a non-invasive medical imaging technique which enables in vivo visualisation and various types of quantitative studies of white matter fibre tracts connecting different parts of the brain. We completed a quantitative study using brain tractography with diffusion tensor imaging in patients with mild cognitive impairment, patients with Alzheimer disease, and normal controls, in order to analyse the reproducibility and validity of the results. SUBJECTS AND METHODS: Fractional anisotropy (FA) and mean diffusivity (MD) were measured across the uncinate fasciculus and the posterior cingulate fasciculus in images, obtained from a database and a research centre, representing 52 subjects distributed among the 3 study groups. Two observers took the measurements twice in order to evaluate intra- and inter-observer reproducibility. RESULTS: Measurements of FA and MD of the uncinate fasciculus delivered an intraclass correlation coefficient above 0.9; ICC was above 0.68 for the posterior cingulate fasciculus. Patients with Alzheimer disease showed lower values of FA and higher MD values in the right uncinate fasciculus in images from the research centre. A comparison of the measurements from the 2 centres revealed significant differences. CONCLUSION: We established a reproducible methodology for performing tractography of the tracts in question. FA and MD indexes may serve as early indicators of Alzheimer disease. The type of equipment and the method used to acquire images must be considered because they may alter results as shown by comparing the 2 data sets in this study. PMID:23582374

Larroza, A; Moratal, D; D'ocón Alcañiz, V; Arana, E

2013-04-10

4

The Role of the Arcuate Fasciculus in Conduction Aphasia  

ERIC Educational Resources Information Center

|In aphasia literature, it has been considered that a speech repetition defect represents the main constituent of conduction aphasia. Conduction aphasia has frequently been interpreted as a language impairment due to lesions of the arcuate fasciculus (AF) that disconnect receptive language areas from expressive ones. Modern neuroradiological…

Bernal, Byron; Ardila, Alfredo

2009-01-01

5

MR Imaging of the Temporal Stem: Anatomic Dissection Tractography of the Uncinate Fasciculus, Inferior Occipitofrontal Fasciculus, and Meyer's Loop of the Optic Radiation  

Microsoft Academic Search

BACKGROUND AND PURPOSE: The MR anatomy of the uncinate fasciculus, inferior occipitofrontal fasciculus, and Meyer's loop of the optic radiation, which traverse the temporal stem, is not well known. The purpose of this investigation was to study these structures in the anterior temporal lobe and the external and extreme capsules and to correlate the dissected anatomy with the cross-sectional MR

E. Leon Kier; Lawrence H. Staib; Lawrence M. Davis; Richard A. Bronen

6

Does the left inferior longitudinal fasciculus play a role in language? A brain stimulation study  

Microsoft Academic Search

Although advances in diffusion tensor imaging have enabled us to better study the anatomy of the inferior long- itudinal fasciculus (ILF), its function remains poorly understood. Recently, it was suggested that the subcortical network subserving the language semantics could be constituted, in parallel with the inferior occipitofrontal fasciculus, by the left ILF, joining the posterior occipitotemporal regions to the temporal

Emmanuel Mandonnet; Aurelien Nouet; Peggy Gatignol; Laurent Capelle; Hugues Duffau

2007-01-01

7

Does the Left Inferior Longitudinal Fasciculus Play a Role in Language? A Brain Stimulation Study  

ERIC Educational Resources Information Center

|Although advances in diffusion tensor imaging have enabled us to better study the anatomy of the inferior longitudinal fasciculus (ILF), its function remains poorly understood. Recently, it was suggested that the subcortical network subserving the language semantics could be constituted, in parallel with the inferior occipitofrontal fasciculus,…

Mandonnet, Emmanuel; Nouet, Aurelien; Gatignol, Peggy; Capelle, Laurent; Duffau, Hugues

2007-01-01

8

Asymmetries of the Arcuate Fasciculus in Monozygotic Twins: Genetic and Nongenetic Influences  

PubMed Central

We assessed cerebral asymmetry for language in 35 monozygotic twin pairs. Using DTI, we reconstructed the arcuate fasciculus in each twin. Among the male twins, right-handed pairs showed greater left-sided asymmetry of connectivity in the arcuate fasciculus than did those with discordant handedness, and within the discordant group the right-handers had greater left-sided volume asymmetry of the arcuate fasciculus than did their left-handed co-twins. There were no such effects in the female twins. Cerebral asymmetry for language showed more consistent results, with the more left-cerebrally dominant twins also showing more leftward asymmetry of high anisotropic fibers in the arcuate fasciculus, a result applying equally to female as to male twins. Reversals of arcuate fasciculus asymmetry were restricted to pairs discordant for language dominance, with the left-cerebrally dominant twins showing leftward and the right-cerebrally dominant twins rightward asymmetry of anisotropic diffusion in the arcuate fasciculus. Because monozygotic twin pairs share the same genotype, our results indicate a strong nongenetic component in arcuate fasciculus asymmetry, particularly in those discordant for cerebral asymmetry.

Haberling, Isabelle S.; Badzakova-Trajkov, Gjurgjica; Corballis, Michael C.

2013-01-01

9

Reading impairment in a patient with missing arcuate fasciculus  

PubMed Central

We describe the case of a child (“S”) who was treated with radiation therapy at age 5 for a recurrent malignant brain tumor. Radiation successfully abolished the tumor but caused radiation-induced tissue necrosis, primarily affecting cerebral white matter. S was introduced to us at age 15 because of her profound dyslexia. We assessed cognitive abilities and performed diffusion tensor imaging (DTI) to measure cerebral white matter pathways. Diffuse white matter differences were evident in T1-weighted, T2-weighted, diffusion anisotropy, and mean diffusivity measures in S compared to a group of 28 normal female controls. In addition, we found specific white matter pathway deficits by comparing tensor orientation directions in S’s brain with those of the control brains. While her principal diffusion direction maps appeared consistent with those of controls over most of the brain, there were tensor orientation abnormalities in the fiber tracts that form the superior longitudinal fasciculus (SLF) in both hemispheres. Tractography analysis indicated that the left and right arcuate fasciculus (AF), as well as other tracts within the SLF, were missing in S. Other major white matter tracts, such as the corticospinal and inferior occipitofrontal pathways, were intact. Functional MRI measurements indicated left-hemisphere dominanance for language with a normal activation pattern. Despite the left AF abnormality, S had preserved oral language with average sentence repetition skills. In addition to profound dyslexia, S exhibited visuospatial, calculation, and rapid naming deficits and was impaired in both auditory and spatial working memory. We propose that the reading and visuospatial deficits were due to the abnormal left and right SLF pathways, respectively. These results advance our understanding of the functional significance of the SLF and are the first to link radiation necrosis with selective damage to a specific set of fiber tracts.

Rauschecker, Andreas M.; Deutsch, Gayle K.; Ben-Shachar, Michal; Schwartzman, Armin; Perry, Lee M.; Dougherty, Robert F.

2009-01-01

10

Learning to Read Improves the Structure of the Arcuate Fasciculus.  

PubMed

The acquisition of literacy results from an effortful learning process that leads to functional changes in several cortical regions. We explored whether learning to read also leads to anatomical changes within the left intrahemispheric white matter pathways that interconnect these regions. Using diffusion tensor imaging tractography, we compared illiterates with ex-illiterates who learned to read during adulthood and literates who learned to read during their childhood. Literacy related to an increase in fractional anisotropy and a decrease in perpendicular diffusivity in the temporo-parietal portion of the left arcuate fasciculus. The microstructure within this pathway correlated with the reading performance and the degree of functional activation within 2 dominant brain regions involved in reading: The Visual Word Form Area in response to letter strings, and the posterior superior temporal cortex in response to spoken language. Thus, the acquisition of literacy is associated with a reinforcement of left temporo-parietal connections whose microstructure predicts overall reading performance and the functional specialization of the Visual Word Form Area. This anatomical magnetic resonance imaging marker may be useful to predict developmental reading disorders. PMID:23236205

Thiebaut de Schotten, Michel; Cohen, Laurent; Amemiya, Eduardo; Braga, Lucia W; Dehaene, Stanislas

2012-12-12

11

A tractography study in dyslexia: neuroanatomic correlates of orthographic, phonological and speech processing.  

PubMed

Diffusion tensor imaging tractography is a structural magnetic resonance imaging technique allowing reconstruction and assessment of the integrity of three dimensional white matter tracts, as indexed by their fractional anisotropy. It is assumed that the left arcuate fasciculus plays a crucial role for reading development, as it connects two regions of the reading network, the left temporoparietal region and the left inferior frontal gyrus, for which atypical functional activation and lower fractional anisotropy values have been reported in dyslexic readers. In addition, we explored the potential role of the left inferior fronto-occipital fasciculus, which might connect a third region of the reading network, the left ventral occipitotemporal region with the left inferior frontal gyrus. In the present study, 20 adults with dyslexia and 20 typical reading adults were scanned using diffusion tensor imaging, and the bilateral arcuate fasciculus and the left inferior fronto-occipital fasciculus were delineated. Group comparisons show a significantly reduced fractional anisotropy in the left arcuate fasciculus of adults with dyslexia, in particular in the segment that directly connects posterior temporal and frontal areas. This fractional anisotropy reduction might reflect a lower degree of myelination in the dyslexic sample, as it co-occurred with a group difference in radial diffusivity. In contrast, no significant group differences in fractional anisotropy were found in the right arcuate fasciculus or in the left inferior fronto-occipital fasciculus. Correlational analyses (controlled for reading status) demonstrated a specific relation between performance on phoneme awareness and speech perception and the integrity of left arcuate fasciculus as indexed by fractional anisotropy, and between orthographic processing and fractional anisotropy values in left inferior fronto-occipital fasciculus. The present study reveals structural anomalies in the left arcuate fasciculus in adults with dyslexia. This finding corroborates current hypotheses of dyslexia as a disorder of network connections. In addition, our study demonstrates a correlational double dissociation, which might reflect neuroanatomical correlates of the dual route reading model: the left arcuate fasciculus seems to sustain the dorsal phonological route underlying grapheme-phoneme decoding, while the left inferior fronto-occipital fasciculus seems to sustain the ventral orthographic route underlying reading by direct word access. PMID:22327793

Vandermosten, Maaike; Boets, Bart; Poelmans, Hanne; Sunaert, Stefan; Wouters, Jan; Ghesquière, Pol

2012-02-10

12

Uncinate Fasciculus Findings in Schizophrenia: A Magnetic Resonance Diffusion Tensor Imaging Study  

PubMed Central

Objective Disruptions in connectivity between the frontal and temporal lobes may explain some of the symptoms observed in schizophrenia. Conventional magnetic resonance imaging (MRI) studies, however, have not shown compelling evidence for white matter abnormalities, because white matter fiber tracts cannot be visualized by conventional MRI. Diffusion tensor imaging is a relatively new technique that can detect subtle white matter abnormalities in vivo by assessing the degree to which directionally organized fibers have lost their normal integrity. The first three diffusion tensor imaging studies in schizophrenia showed lower anisotropic diffusion, relative to comparison subjects, in whole-brain white matter, prefrontal and temporal white matter, and the corpus callosum, respectively. Here the authors focus on fiber tracts forming temporal-frontal connections. Method Anisotropic diffusion was assessed in the uncinate fasciculus, the most prominent white matter tract connecting temporal and frontal brain regions, in 15 patients with chronic schizophrenia and 18 normal comparison subjects. A 1.5-T GE Echospeed system was used to acquire 4-mm-thick coronal line-scan diffusion tensor images. Maps of the fractional anisotropy were generated to quantify the water diffusion within the uncinate fasciculus. Results Findings revealed a group-by-side interaction for fractional anisotropy and for uncinate fasciculus area, derived from automatic segmentation. The patients with schizophrenia showed a lack of normal left-greater-than-right asymmetry seen in the comparison subjects. Conclusions These findings demonstrate the importance of investigating white matter tracts in vivo in schizophrenia and support the hypothesis of a disruption in the normal pattern of connectivity between temporal and frontal brain regions in schizophrenia.

Kubicki, Marek; Westin, Carl-Fredrik; Maier, Stephan E.; Frumin, Melissa; Nestor, Paul G.; Salisbury, Dean F.; Kikinis, Ron; Jolesz, Ferenc A.; McCarley, Robert W.; Shenton, Martha E.

2009-01-01

13

Damage to the anterior arcuate fasciculus predicts non-fluent speech production in aphasia.  

PubMed

Non-fluent aphasia implies a relatively straightforward neurological condition characterized by limited speech output. However, it is an umbrella term for different underlying impairments affecting speech production. Several studies have sought the critical lesion location that gives rise to non-fluent aphasia. The results have been mixed but typically implicate anterior cortical regions such as Broca's area, the left anterior insula, and deep white matter regions. To provide a clearer picture of cortical damage in non-fluent aphasia, the current study examined brain damage that negatively influences speech fluency in patients with aphasia. It controlled for some basic speech and language comprehension factors in order to better isolate the contribution of different mechanisms to fluency, or its lack. Cortical damage was related to overall speech fluency, as estimated by clinical judgements using the Western Aphasia Battery speech fluency scale, diadochokinetic rate, rudimentary auditory language comprehension, and executive functioning (scores on a matrix reasoning test) in 64 patients with chronic left hemisphere stroke. A region of interest analysis that included brain regions typically implicated in speech and language processing revealed that non-fluency in aphasia is primarily predicted by damage to the anterior segment of the left arcuate fasciculus. An improved prediction model also included the left uncinate fasciculus, a white matter tract connecting the middle and anterior temporal lobe with frontal lobe regions, including the pars triangularis. Models that controlled for diadochokinetic rate, picture-word recognition, or executive functioning also revealed a strong relationship between anterior segment involvement and speech fluency. Whole brain analyses corroborated the findings from the region of interest analyses. An additional exploratory analysis revealed that involvement of the uncinate fasciculus adjudicated between Broca's and global aphasia, the two most common kinds of non-fluent aphasia. In summary, the current results suggest that the anterior segment of the left arcuate fasciculus, a white matter tract that lies deep to posterior portions of Broca's area and the sensory-motor cortex, is a robust predictor of impaired speech fluency in aphasic patients, even when motor speech, lexical processing, and executive functioning are included as co-factors. Simply put, damage to those regions results in non-fluent aphasic speech; when they are undamaged, fluent aphasias result. PMID:24131592

Fridriksson, Julius; Guo, Dazhou; Fillmore, Paul; Holland, Audrey; Rorden, Chris

2013-10-15

14

A Combined fMRI and DTI Examination of Functional Language Lateralization and Arcuate Fasciculus Structure: Effects of Degree versus Direction of Hand Preference  

ERIC Educational Resources Information Center

|The present study examined the relationship between hand preference degree and direction, functional language lateralization in Broca's and Wernicke's areas, and structural measures of the arcuate fasciculus. Results revealed an effect of degree of hand preference on arcuate fasciculus structure, such that consistently-handed individuals,…

Propper, Ruthe E.; O'Donnell, Lauren J.; Whalen, Stephen; Tie, Yanmei; Norton, Isaiah H.; Suarez, Ralph O.; Zollei, Lilla; Radmanesh, Alireza; Golby, Alexandra J.

2010-01-01

15

Preliminary Evidence of White Matter Abnormality in the Uncinate Fasciculus in Generalized Social Anxiety Disorder  

PubMed Central

Background Individuals with generalized social anxiety disorder (GSAD) exhibit exaggerated amygdala reactivity to aversive social stimuli. These findings could be explained by microstructural abnormalities in white matter (WM) tracts that connect the amygdala and prefrontal cortex, which is known to modulate the amygdala’s response to threat. The goal of this study was to investigate brain frontal WM abnormalities by using diffusion tensor imaging (DTI) in patients with social anxiety disorder. Method A Turboprop DTI sequence was used to acquire diffusion tensor images in thirty patients with GSAD and thirty matched healthy controls. Fractional anisotropy, an index of axonal organization, within WM was quantified in individual subjects and an automated voxel-based, whole-brain method was used to analyze group differences. Results Compared to healthy controls, patients had significantly lower fractional anisotropy localized to the right uncinate fasciculus WM near the orbitofrontal cortex. There were no areas of higher fractional anisotropy in patients than controls. Conclusions These findings point to an abnormality in the uncinate fasciculus, the major WM tract connecting the frontal cortex to the amygdala and other limbic temporal regions, in GSAD which could underlie the aberrant amygdala-prefrontal interactions resulting in dysfunctional social threat processing in this illness.

Phan, K. Luan; Orlichenko, Anton; Boyd, Erin; Angstadt, Mike; Coccaro, Emil F.; Liberzon, Israel; Arfanakis, Konstantinos

2009-01-01

16

Predicting Behavioral Deficits in Pediatric Traumatic Brain Injury Through Uncinate Fasciculus Integrity  

PubMed Central

Behavioral dysregulation is a common and detrimental consequence of traumatic brain injury (TBI) in children that contributes to poor academic achievement and deficits in social development. Unfortunately, behavioral dysregulation is difficult to predict from either injury severity or early neuropsychological evaluation. The uncinate fasciculus (UF) connects orbitofrontal and anterior temporal lobes, which are commonly implicated in emotional and behavioral regulation. Using probabilistic diffusion tensor tractography (DTT), we examined the relationship between the integrity of the UF 3 months post-injury and ratings of executive functions 12 months post-injury in children with moderate to severe TBI and a comparison group with orthopedic injuries. As expected, fractional anisotropy of the UF was lower in the TBI group relative to the orthopedic injury group. DTT metrics from the UF served as a biomarker and predicted ratings of emotional and behavior regulation, but not metacognition. In contrast, the Glasgow Coma Scale score was not related to either UF integrity or to executive function outcomes. Neuroanatomical biomarkers like the uncinate fasciculus may allow for early identification of behavioral problems and allow for investigation into the relationship of frontotemporal networks to brain-behavior relationships.

Johnson, Chad P.; Juranek, Jenifer; Kramer, Larry A.; Prasad, Mary R.; Swank, Paul R.; Ewing-Cobbs, Linda

2013-01-01

17

Disynaptic excitation from the medial longitudinal fasciculus to lumbosacral motoneurons: modulation by repetitive activation, descending pathways, and locomotion  

Microsoft Academic Search

Short-latency excitatory postsynaptic potentials (EPSPs) evoked by stimulation in the medial longitudinal fasciculus (MLF) were recorded intracellularly from motoneurons in the cat lumbosacral spinal cord. Monosynaptic and disynaptic EPSPs occurred in most flexor and extensor motoneurons studied. These EPSPs resulted from the activation of fast (> 100 m\\/s) descending axons from the MLF to the spinal cord. Several features distinguished

M. K. Floeter; G. N. Sholomenko; J.-P. Gossard; R. E. Burke

1993-01-01

18

Vertical gaze palsy and selective unilateral infarction of the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF)  

Microsoft Academic Search

We report a clinico-pathological correlation study in a patient with basilar artery thrombosis, who developed tetraplegia and combined up- and downgaze palsy involving voluntary saccades and visually-guided movements, but sparing the oculocephalic responses. At necropsy, apart from bilateral infarction in the basis pontis, there was a single unilateral infarct selectively destroying the rostral interstitial nucleus of the medial longitudinal fasciculus

J Bogousslavsky; J Miklossy; F Regli; R Janzer

1990-01-01

19

Dissociation of Behavioral Changes in Rats Resulting From Lesions of the Habenula Versus Fasciculus Retroflexus and Their Possible Anatomical Substrates  

Microsoft Academic Search

Lesions in either the habenula or its primary efferent pathway, the fasciculus retroflexus (FR), impaired avoidance responding. However, lesions of only the FR provided a persistent elevation of locomotor activity. Immunocytochemical study of the interpeduncular nucleus (IPN) through injection of retrograde tracers into the IPN and the overlying ventral tegmental area indicated that habenular lesions spared both rostral habenula and

Everard W. Thornton; Marion Murray; Theresa Connors-Eckenrode; Forrest Haun

1994-01-01

20

Evidence of slow maturation of the superior longitudinal fasciculus in early childhood by diffusion tensor imaging.  

PubMed

While the majority of axonal organization is established by birth in mammalian brains, axonal wiring and pruning processes, as well as myelination, are known to extend to the postnatal periods, where environmental stimuli often play a major role. Normal axonal and myelin development of individual white matter tracts of human in this period is poorly understood and may have a major role in cognitive development of human. In this study, we applied diffusion tensor imaging and normalization-based population analyses to 44 preteen children and 30 adult images. We observed highly significant changes of fiber orientations at regions that correspond to the superior longitudinal fasciculus during the first 5 years. The result is attributed to slow axonal and/or myelin maturation of this tract, which is believed to be involved in language functions. PMID:17826183

Zhang, Jiangyang; Evans, Alan; Hermoye, Laurent; Lee, Seung-Koo; Wakana, Setsu; Zhang, Weihong; Donohue, Pamela; Miller, Michael I; Huang, Hao; Wang, Xiaoqing; van Zijl, Peter C M; Mori, Susumu

2007-08-08

21

Is the term "fasciculus opticus cerebralis" more justifiable than the term "optic nerve"?  

PubMed

The terminology of the optic nerve had already been changed three times, since 1895 until 1955 when the term "nervus opticus" was introduced in the "Terminologia Anatomica". Following our study we claim that, from the aspect of phylogenetic evolution of binocular vision development as well as optical embryogenesis where opticus is evidently presented as a product of diencephalic structures, the addition of the term "nervus" to opticus is not adequate and justified. From the clinical aspect the term "nervus opticus" is also inadequate, both as a "nerve" that has no functional regenerative properties, unlike other cranial nerves, as well as from a pedagogical and didactical aspect of educating future physicians. We suggest that the term "Fasciculus Opticus Cerebralis" should be used as it much better explains the origin as well as its affiliation to the central nervous system. PMID:23837214

Vojnikovi?, Bojo; Bajek, Snjezana; Bajek, Goran; Strenja-Lini?, Ines; Grubesi?, Aron

2013-04-01

22

Relatively normal repetition performance despite severe disruption of the left arcuate fasciculus  

PubMed Central

The arcuate fasciculus (AF) is believed to be fundamental to the neural circuitry behind many important cognitive processes. Connecting Wernicke’s and Broca’s area, these fibers are thought to be especially important for repetition. In this case study we present evidence from a patient that set doubt on these assumptions. We present structural imaging, diffusion tensor imaging, and language data on a patient with a large left-sided stroke and severely damaged left AF who showed intact word repetition and relatively intact sentence repetition performance. Specifically, his sentence repetition is more fluent and grammatical, with less hesitation than spontaneous speech, and with rare omissions only during the longest sentences. These results challenge classical theories that maintain the left AF is the dominant language processing pathway or mechanism for repetition.

Epstein-Peterson, Zachary; Faria, Andreia Vasconcellos; Mori, Susumu; Hillis, Argye E.; Tsapkini, Kyrana

2012-01-01

23

A Combined fMRI and DTI Examination of Functional Language Lateralization and Arcuate Fasciculus Structure: Effects of Degree Versus Direction of Hand Preference  

PubMed Central

The present study examined the relationship between hand preference degree and direction, functional language lateralization in Broca's and Wernicke's areas, and structural measures of the arcuate fasciculus. Results revealed an effect of degree of hand preference on arcuate fasciculus structure, such that consistently-handed individuals, regardless of the direction of hand preference, demonstrated the most asymmetric arcuate fasciculus, with larger left versus right arcuate, as measured by DTI. Functional language lateralization in Wernicke's area, measured via fMRI, was related to arcuate fasciculus volume in consistent-left-handers only, and only in people who were not right hemisphere lateralized for language; given the small sample size for this finding, future investigation is warranted. Results suggest handedness degree may be an important variable to investigate in the context of neuroanatomical asymmetries.

Propper, Ruth E.; O'Donnell, Lauren J.; Whalen, Stephen; Tie, Yanmei; Norton, Isaiah H.; Suarez, Ralph O.; Zollei, Lilla; Radmanesh, Alireza; Golby, Alexandra J.

2010-01-01

24

Long-term Cognitive and Behavioral Therapies, Combined with Augmentative Communication, are Related to Uncinate Fasciculus Integrity in Autism  

Microsoft Academic Search

Recent evidence points to white-matter abnormalities as a key factor in autism physiopathology. Using Diffusion Tensor Imaging,\\u000a we studied white-matter structural properties in a convenience sample of twenty-two subjects with low-functioning autism exposed\\u000a to long-term augmentative and alternative communication, combined with sessions of cognitive and behavioral therapy. Uncinate\\u000a fasciculus structural properties correlated significantly with therapy length and early onset, as

Matteo Pardini; Maurizio Elia; Francesco G. Garaci; Silvia Guida; Filadelfo Coniglione; Frank Krueger; Francesca Benassi; Leonardo Emberti Gialloreti

25

The anatomical characteristics of superior longitudinal fasciculus I in human brain: Diffusion tensor tractography study.  

PubMed

The superior longitudinal fasciculus (SLF) I is known to be involved in regulation of higher aspects of motor function. Using diffusion tensor imaging (DTI), we attempted to identify the SLF I and to investigate the anatomical characteristics of the SLF I in the human brain. We recruited 30 healthy subjects for this study. The SLF I was obtained using the FMRIB Software Library. The seed region of interest (ROI) was given at the superior parietal lobule (SPL) and the target ROI was the supplementary motor area (SMA) along with the dorsal part of the premotor area (PMA). Values of fractional anisotropy (FA), mean diffusivity (MD), and tract volume were measured. The SLF I originated from the SPL and medial parietal cortex, passed through the white matter of the SPL and superior frontal gyrus, and then terminated in the SMA and dorsal PMA. There were no significant differences between hemispheres in terms of the FA, MD, and tract volume. We present with the anatomical characteristics of the SLF I in the human brain using DTI. We think that the methodology and results of this study would be helpful to researchers in this field. PMID:22085696

Jang, Sung Ho; Hong, Ji Heon

2011-11-06

26

Midbrain vs. pontine medial longitudinal fasciculus lesions: the utilization of masseter and blink reflexes.  

PubMed

Masseter (MR) and blink reflexes (BL) were investigated in 51 patients with internuclear ophthalmoplegia (INO) due to multiple sclerosis (28) and lacunar infarction (23). The MR was abnormal in 20 of 23 cases with bilateral INO and in 21 of 28 with unilateral INO. The R1 component of the BL (BL-R1) was abnormal in 7 of 23 patients with bilateral INO and 10 of 28 with unilateral INO. Combined MR and BL-R1 changes occurred in 8 of 28 cases with unilateral INO and 7 of 23 with bilateral INO. The findings provide evidence for a rostral/caudal localization of lesions within the medial longitudinal fasciculus causing INO on the basis of MR and BL-R1 abnormalities. An abnormality limited to MR suggests a midbrain location in 58.8% of patients while abnormal BL-R1 with or without an associated MR change suggests a rostral pontine location in 35.3%. PMID:2027350

Hopf, H C; Thömke, F; Gutmann, L

1991-04-01

27

Neural injury of uncinate fasciculus in patients with diffuse axonal injury.  

PubMed

The recent development of diffusion tensor imaging (DTI) allows visualization and estimation of the uncinate fasciculus (UF). We investigated injuries of the UF in patients with diffuse axonal injury (DAI) who showed no specific lesions except for DAI lesions on conventional brain MRI. Twenty-one chronic patients with DAI, and 21 age- and sex-matched normal control subjects were recruited for this study. Diffusion tensor images were acquired using a sensitivity-encoding head coil at 1.5 T and the UF was reconstructed using DTI-Studio software. Fractional anisotropy (FA), apparent diffusion coefficient (ADC) value, and fiber number of the UF were measured. In the DAI group, the FA values and fiber numbers were significantly decreased compared to those of the control group (P< 0.05). The FA value and fiber number decreased 8.4% and 26.5% in the DAI group compared to those of the control group. By contrast, the ADC value did not show any difference between the DAI and control groups (P> 0.05). Changes in the DTI parameters of the DAI group appeared to indicate neural injury of the UF. We believe that DTI can be a useful evaluation tool for detecting hidden neural injuries of UF in patients with DAI. PMID:22672947

Seo, Jeong Pyo; Kim, Oh Lyong; Kim, Seong Ho; Chang, Min Cheol; Kim, Min-Su; Son, Su Min; Jang, Sung Ho

2012-01-01

28

Effects of practice and experience on the arcuate fasciculus: comparing singers, instrumentalists, and non-musicians.  

PubMed

Structure and function of the human brain are affected by training in both linguistic and musical domains. Individuals with intensive vocal musical training provide a useful model for investigating neural adaptations of learning in the vocal-motor domain and can be compared with learning in a more general musical domain. Here we confirm general differences in macrostructure (tract volume) and microstructure (fractional anisotropy, FA) of the arcuate fasciculus (AF), a prominent white-matter tract connecting temporal and frontal brain regions, between singers, instrumentalists, and non-musicians. Both groups of musicians differed from non-musicians in having larger tract volume and higher FA values of the right and left AF. The AF was then subdivided in a dorsal (superior) branch connecting the superior temporal gyrus and the inferior frontal gyrus (STG???IFG), and ventral (inferior) branch connecting the middle temporal gyrus and the inferior frontal gyrus (MTG???IFG). Relative to instrumental musicians, singers had a larger tract volume but lower FA values in the left dorsal AF (STG???IFG), and a similar trend in the left ventral AF (MTG???IFG). This between-group comparison controls for the general effects of musical training, although FA was still higher in singers compared to non-musicians. Both musician groups had higher tract volumes in the right dorsal and ventral tracts compared to non-musicians, but did not show a significant difference between each other. Furthermore, in the singers' group, FA in the left dorsal branch of the AF was inversely correlated with the number of years of participants' vocal training. Our findings suggest that long-term vocal-motor training might lead to an increase in volume and microstructural complexity of specific white-matter tracts connecting regions that are fundamental to sound perception, production, and its feedforward and feedback control which can be differentiated from a more general musician effect. PMID:21779271

Halwani, Gus F; Loui, Psyche; Rüber, Theodor; Schlaug, Gottfried

2011-07-07

29

Correlation between uncinate fasciculus and memory tasks in healthy individual using diffusion tensor tractography.  

PubMed

Tractography is a procedure that can track and demonstrate the 3D neural tracts of the white matter of the brain. The images of the brain are obtained by analyzing the diffusion tensor, identification of which can provide the anatomical connections of the brain. Studying these connections is integral to the understanding of the brain function. Specifically, the uncinate fasciculus (UF), which is the white matter in the human brain, is said to be related to cognitive function. The UF tractography is calculated using diffusion tensor imaging (DTI) parameter. Studies have shown that the DTI parameter of dementia patients is lower than that of healthy individuals. It is also suggested that the DTI parameter of healthy individuals decreases with age. In addition, the WMS-R score, which is indicative of general memory, verbal memory and other cognitive functions, of the elderly are lower than of the young. However, there is no report yet that has holistically investigated DTI parameter and the memory functions. Thus, in this research, we have calculated the correlation coefficient between the DTI parameter of UF and WMS-R score. Our result shows that the correlation coefficient of diffusivity of the fiber direction and visual memory of a left UF is -0.226 at the maximum. Correlation between DTI measurement and memory performance suggests the relationships between the UF and function in memory tasks lateralization. Our finding matches previous reports on the correlation between FA in the left, or L1 in the right UF, and performance on visual memory. PMID:23365919

Sato, T; Maruyama, N; Hoshida, T; Minato, K

2012-01-01

30

Aberrations in the arcuate fasciculus are associated with auditory verbal hallucinations in psychotic and in non-psychotic individuals.  

PubMed

The pathophysiology of auditory verbal hallucinations (AVH) is still unclear. Cognitive as well as electrophysiological studies indicate that a defect in sensory feedback (corollary discharge) may contribute to the experience of AVH. This could result from disruption of the arcuate fasciculus, the major tract connecting frontal and temporo-parietal language areas. Previous diffusion tensor imaging studies indeed demonstrated abnormalities of this tract in schizophrenia patients with AVH. It is, however, difficult to disentangle specific associations with AVH in this patient group as many other factors, such as other positive and negative symptoms, medication or halted education could likewise have affected tract integrity. We therefore investigated AVH in relative isolation and studied a group of non-psychotic individuals with AVH as well as patients with AVH and non-hallucinating matched controls. We compared tract integrity of the arcuate fasiculus and of three other control tracts, between 35 non-psychotic individuals with AVH, 35 schizophrenia patients with AVH, and 36 controls using diffusion tensor imaging and magnetization transfer imaging. Both groups with AVH showed an increase in magnetization transfer ratio (MTR) in the arcuate fasciculus, but not in the other control tracts. In addition, a general decrease in fractional anisotropy (FA) for almost all bundles was observed in the patient group, but not in the non-psychotic individuals with AVH. As increased MTR in the arcuate fasciculus was present in both hallucinating groups, a specific association with AVH seems plausible. Decreases in FA, on the other hand, seem to be related to other disease processes of schizophrenia. PMID:22109992

de Weijer, Antoin D; Neggers, Sebastiaan F W; Diederen, Kelly M S; Mandl, René C W; Kahn, René S; Hulshoff Pol, Hilleke E; Sommer, Iris E

2011-11-23

31

Horizontal portion of arcuate fasciculus fibers track to pars opercularis, not pars triangularis, in right and left hemispheres: A DTI study  

Microsoft Academic Search

The arcuate fasciculus (AF) is a white matter pathway traditionally considered to connect left Broca's area with posterior language zones. We utilized diffusion tensor imaging (DTI) in eight healthy subjects (5 M) to track pathways in the horizontal mid-portion of the AF (hAF) to subregions of Broca's area — pars triangularis (PTr) and pars opercularis (POp); and to ventral premotor

Elina Kaplan; Margaret A. Naeser; Paula I. Martin; Michael Ho; Yunyan Wang; Errol Baker; Alvaro Pascual-Leone

2010-01-01

32

Selective neurotoxic effects of nicotine on axons in fasciculus retroflexus further support evidence that this a weak link in brain across multiple drugs of abuse  

Microsoft Academic Search

When administered continuously for several days at relatively low plasma levels, a variety of drugs of abuse with strong dopaminergic actions induce degeneration in axons traveling from the lateral habenula through the sheath of fasciculus retroflexus to midbrain monoaminergic nuclei. With some of these drugs, such as cocaine, this is virtually the only degeneration induced in brain. Nicotine given continuously

Janice Carlson; Brian Armstrong; Robert C. Switzer III; Gaylord Ellison

2000-01-01

33

Neural degeneration following chronic stimulant abuse reveals a weak link in brain, fasciculus retroflexus, implying the loss of forebrain control circuitry  

Microsoft Academic Search

There is increasing evidence that the fasciculus retroflexus (FR) represents a ‘weak link’ following the continuous administration of drugs of abuse. A variety of drugs which predominantly potentiate dopamine, including d-amphetamine, methamphetamine, MDMA, cocaine, and cathinone, all induce degeneration in axons from lateral habenula, through the sheath of FR, to midbrain cells such as SN, VTA, and raphe. For some

Gaylord Ellison

2002-01-01

34

Vertical gaze palsy and selective unilateral infarction of the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF).  

PubMed Central

We report a clinico-pathological correlation study in a patient with basilar artery thrombosis, who developed tetraplegia and combined up- and downgaze palsy involving voluntary saccades and visually-guided movements, but sparing the oculocephalic responses. At necropsy, apart from bilateral infarction in the basis pontis, there was a single unilateral infarct selectively destroying the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) on the right. The posterior commissure and its nucleus, the nucleus of Cajal, the nucleus of Darkschewitsch and the pontine tegmentum were spared. We suggest that the unilateral riMLF lesion may have disrupted bilateral upgaze excitatory and inhibitory inputs and unilateral downgaze excitatory inputs. The functional anatomy of inhibitory and excitatory vertical gaze circuitry, which remains speculative, may explain why a unilateral lesion of the upper midbrain tegmentum may be sufficient to generate an upgaze palsy or a combined up- and downgaze palsy, while an isolated downgaze palsy requires bilateral lesions. Images

Bogousslavsky, J; Miklossy, J; Regli, F; Janzer, R

1990-01-01

35

42 CFR 488.30 - Revisit user fee for revisit surveys.  

Code of Federal Regulations, 2010 CFR

... false Revisit user fee for revisit surveys. 488.30 Section 488.30 Public...CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES...488.30 Revisit user fee for revisit surveys. (a) Definitions. As used...

2009-10-01

36

42 CFR 488.30 - Revisit user fee for revisit surveys.  

Code of Federal Regulations, 2010 CFR

... false Revisit user fee for revisit surveys. 488.30 Section 488.30 Public...CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES...488.30 Revisit user fee for revisit surveys. (a) Definitions. As used...

2010-10-01

37

Network Nation Revisited  

NSDL National Science Digital Library

The Network Nation Revisited" is an analysis of the predictions made by Hiltz and Turoff in _The Network Nation_, one of the seminal texts (published in 1978) in the field of Computer Mediated Communications.

38

Abnormal Language Pathway in Children with Angelman Syndrome  

PubMed Central

Angelman Syndrome is a genetic disorder characterized by pervasive developmental disability with failure to develop speech. We examined the basis for severe language delay in Angelman Syndrome patients using diffusion tensor imaging. Magnetic Resonance Imaging/diffusion tensor imaging was performed in seven genetically confirmed Angelman Syndrome children (age:70±26 months, five males) and four age-matched controls to investigate the microstructural integrity of arcuate fasciculus and other major association tracts. Six of seven Angelman Syndrome children had unidentifiable left arcuate fasciculus while all controls had identifiable arcuate fasciculus. The right arcuate fasciculus was absent in six of seven Angelman Syndrome children and one of four controls. Diffusion tensor imaging color map suggested aberrant morphology of the arcuate fasciculus region. Other association tracts, including uncinate fasciculus, inferior-fronto-occipital fasciculus, inferior-longitudinal fasciculus, and corticospinal tract, were identifiable but showed decreased fractional anisotropy in Angelman Syndrome children. Increased apparent diffusion coefficient was seen in all tracts except uncinate fasciculus when compared to controls. Angelman Syndrome patients have global impairment of white matter integrity in association tracts, particularly, the arcuate fasciculus which shows severe morphological changes. This could be due to a potential problem with axon guidance during brain development possibly due to loss of UBE3A gene expression.

Wilson, Benjamin J.; Sundaram, Senthil K.; Huq, AHM; Jeong, Jeong-Won; Halverson, Stacey R.; Behen, Michael E.; Bui, Duy Q.; Chugani, Harry T.

2011-01-01

39

Deficits in torsional and vertical rapid eye movements and shift of Listing's plane after uni- and bilateral lesions of the rostral interstitial nucleus of the medial longitudinal fasciculus  

Microsoft Academic Search

The rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) contains burst neurons whose activity precedes rapid eye movements with a vertical and\\/or torsional component. To ascertain their causal role in the generation of conjugate eye movements, we placed uni- and bilateral kainic acid lesions in that region. Unilateral inactivation of the riMLF leads to a loss of all rapid

Y. Suzuki; J. A. Biittner-Ennever; D. Straumann; K. Hepp; B. J. M. Hess; V. Henn

1995-01-01

40

The anterior glenohumeral joint capsule: macroscopic and MRI anatomy of the fasciculus obliquus or so-called ligamentum glenohumerale spirale.  

PubMed

The purpose of this study was to demonstrate the macroscopic and MRI anatomy of the fasciculus obliquus, otherwise known as the ligamentum glenohumerale spirale or spiral GHL of the anterior shoulder joint capsule. Conventional and MR arthrography (1.5-T device Somatom Symphony, Siemens with shoulder coil) images in standard planes were compared with gross anatomic dissection findings in six fresh shoulder specimens from three cadavers. The MR imaging protocol included T1, PD and DESS 3D WI sequences. The macroscopically recognisable band-the spiral GHL-was identified by anatomic dissection and MRI in all the specimens. It was best visualised by MR arthrography on axial and oblique sagittal planes (T1; PD WI) and appeared as a low signal intensity stripe within the superficial layer of the anterior joint capsule. The absence of the variable middle glenohumeral ligament did not influence the anatomic properties and the MR imaging of the spiral GHL. Diagnostic visualisation of the normal anatomic structures is a prerequisite to distinguish between normal and pathologic conditions. Anatomy of the spiral GHL can be used by radiologists for more detailed interpretation of the anterior shoulder joint capsule ligaments on MR images. PMID:15022012

Merila, M; Leibecke, T; Gehl, H-B; Busch, L-C; Russlies, M; Eller, A; Haviko, T; Kolts, I

2004-03-12

41

Changes in maps of language function and the integrity of the arcuate fasciculus after therapy for chronic aphasia  

PubMed Central

A patient with chronic aphasia secondary to unilateral stroke in the left hemisphere underwent language testing, diffusion tensor imaging (DTI), and functional imaging using magnetoencephalography (MEG) at four time points: 3 weeks prior to, immediately prior to, immediately after, and 3 months after Constraint Induced Language Therapy (CILT). Performance on language tests involving visual naming and repetition of spoken sentences improved between the immediately prior to and immediately after CILT testing sessions, but not between the pre-CILT sessions. MEG activation in putative pre-morbid language areas of the left hemisphere and homotopic areas of the right hemisphere increased immediately after therapy, as did integrity within the arcuate fasciculus bilaterally. These changes were not evident between the two pre-CILT sessions. While some of these functional, neurophysiological and structural changes had regressed 3 months after therapy, all remained at or above baseline levels. Results provide evidence for an association between improvement in functional status and the increased integrity within a white matter tract known to be involved in language function and its contralateral homologue, as well as increased neurophysiological activity in areas that have the potential to subserve language function bilaterally.

Breier, Joshua I.; Juranek, Jenifer; Papanicolaou, Andrew C.

2012-01-01

42

Sustained attention is associated with right superior longitudinal fasciculus and superior parietal white matter microstructure in children.  

PubMed

Sustained attention develops during childhood and has been linked to the right fronto-parietal cortices in functional imaging studies; however, less is known about its relation to white matter (WM) characteristics. Here we investigated whether the microstructure of the WM underlying and connecting the right fronto-parietal cortices was associated with sustained attention performance in a group of 76 typically developing children aged 7-13 years. Sustained attention was assessed using a rapid visual information processing paradigm. The two behavioral measures of interest were the sensitivity index d' and the coefficient of variation in reaction times (RTCV ). Diffusion-weighted imaging was performed. Mean fractional anisotropy (FA) was extracted from the WM underlying right dorsolateral prefrontal (DLPFC) and parietal cortex (PC), and the right superior longitudinal fasciculus (SLF), as well as equivalent anatomical regions-of-interest (ROIs) in the left hemisphere and mean global WM FA. When analyzed collectively, right hemisphere ROIs FA was significantly associated with d' independently of age. Follow-up analyses revealed that only FA of right SLF and the superior part of the right PC contributed significantly to this association. RTCV was significantly associated with right superior PC FA, but not with right SLF FA. Observed associations remained significant after controlling for FA of equivalent left hemisphere ROIs or global mean FA. In conclusion, better sustained attention performance was associated with higher FA of WM in regions connecting right frontal and parietal cortices. Further studies are needed to clarify to which extent these associations are driven by maturational processes, stable characteristics and/or experience. Hum Brain Mapp 34:3216-3232, 2013. © 2012 Wiley Periodicals, Inc. PMID:22806938

Klarborg, Brith; Skak Madsen, Kathrine; Vestergaard, Martin; Skimminge, Arnold; Jernigan, Terry L; Baaré, William F C

2012-07-17

43

A Hydrostatic Paradox Revisited  

ERIC Educational Resources Information Center

|This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

Ganci, Salvatore

2012-01-01

44

A Hydrostatic Paradox Revisited  

ERIC Educational Resources Information Center

This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

Ganci, Salvatore

2012-01-01

45

CLP(Intervals) Revisited  

Microsoft Academic Search

The design and implementation of constraint logic programming (CLP) languagesover intervals is revisited. Instead of decomposing complex constraints in termsof simple primitive constraints as in CLP(BNR), complex constraints are manipulatedas a whole, enabling more sophisticated narrowing procedures to be appliedin the solver. This idea is embodied in a new CLP language Newton whose operationalsemantics is based on the notion of

Frédéric Benhamou; David A. Mcallester; Pascal Van Hentenryck

1994-01-01

46

Concept Image Revisited  

ERIC Educational Resources Information Center

|Concept image and concept definition is an important construct in mathematics education. Its use, however, has been limited to cognitive studies. This article revisits concept image in the context of research on undergraduate students' understanding of the derivative which regards the context of learning as paramount. The literature, mainly on…

Bingolbali, Erhan; Monaghan, John

2008-01-01

47

Colloquial Hebrew Imperatives Revisited  

ERIC Educational Resources Information Center

|In revisiting Bolozky's [Bolozky, Shmuel, 1979. "On the new imperative in colloquial Hebrew." "Hebrew Annual Review" 3, 17-24] and Bat-El's [Bat-El, Outi, 2002. "True truncation in colloquial Hebrew imperatives." "Language" 78(4), 651-683] analyses of colloquial Hebrew imperatives, the article argues for restricting Imperative Truncation to the…

Bolozky, Shmuel

2009-01-01

48

Google Scholar revisited  

Microsoft Academic Search

Purpose – The purpose of this paper is to revisit Google Scholar. Design\\/methodology\\/approach – This paper discusses the strengths and weaknesses of Google Scholar. Findings – The Google Books project has given a massive and valuable boost to the already rich and diverse content of Google Scholar. The downside of the growth is that significant gaps remain for top ranking

Péter Jacsó

2008-01-01

49

Colloquial Hebrew Imperatives Revisited  

ERIC Educational Resources Information Center

In revisiting Bolozky's [Bolozky, Shmuel, 1979. "On the new imperative in colloquial Hebrew." "Hebrew Annual Review" 3, 17-24] and Bat-El's [Bat-El, Outi, 2002. "True truncation in colloquial Hebrew imperatives." "Language" 78(4), 651-683] analyses of colloquial Hebrew imperatives, the article argues for restricting Imperative Truncation to the…

Bolozky, Shmuel

2009-01-01

50

Revisiting Bioaccumulation Criteria  

EPA Science Inventory

The objective of workgroup 5 was to revisit the B(ioaccumulation) criteria that are currently being used to identify POPs under the Stockholm Convention and PBTs under CEPA, TSCA, REACh and other programs. Despite the lack of a recognized definition for a B substance, we defined ...

51

Imperfect Tagging Revisited  

Microsoft Academic Search

Revisiting Parsons' 1996 article about disability insurance with imperfect tagging in a two type-economy -- individuals are either able or disabled. Here Parsons' analysis is extended in several directions. The model is generalized to allow for different utility functions over work status. The analysis extends to three different cases of a two-type economy. Finally Parsons' model is extended to three

Eric Rehn

2007-01-01

52

Mass Spectrometric Immunoassay Revisited  

NASA Astrophysics Data System (ADS)

The progressive understanding and improvement of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), realized over the years through the considerable efforts of Dr. Marvin Vestal, have made possible numerous comparable efforts involving its application in the biological sciences. Here we revisit the concepts behind one such analytical approach, Mass Spectrometric Immunoassay, which is designed to selectively detect and quantify proteins present in biological milieu.

Nelson, Randall W.; Borges, Chad R.

2011-06-01

53

Revisiting Dialogues and Monologues  

ERIC Educational Resources Information Center

|In educational discourse dialogue tends to be viewed as being (morally) superior to monologue. When we look at them as basic forms of communication, we find that dialogue is a two-way, one-to-one form and monologue is a one-way, one-to-many form. In this paper I revisit the alleged (moral) superiority of dialogue. First, I problematize certain…

Kvernbekk, Tone

2012-01-01

54

Extended pairing model revisited  

NASA Astrophysics Data System (ADS)

The mean-field plus extended pairing model proposed by the authors for describing well-deformed nuclei (F. Pan, V.G. Gueorguiev, J.P. Draayer, Phys. Rev. Lett. 92, 112503 (2004)) is revisited. Eigenvalues of the model can be determined by solving a single transidental equation. Results to date show that even through the model includes many-body interactions, the one- and two-body terms continue to dominate the dynamics for small values of the pairing strength; however, as the strength of the pairing interaction grows, the higher-order terms grow in importance and ultimately dominate. Attempts to extend the theory to the prediction of excited zero plus states did not produce expected results and therefore requires additional consideration.

Draayer, J. P.; Pan, Feng; Gueorguiev, V. G.

2005-09-01

55

Satellite failures revisited  

NASA Astrophysics Data System (ADS)

In January 1994, the two geostationary satellites known as Anik-E1 and Anik-E2, operated by Telesat Canada, failed one after the other within 9 hours, leaving many northern Canadian communities without television and data services. The outage, which shut down much of the country's broadcast television for hours and cost Telesat Canada more than $15 million, generated significant media attention. Lam et al. used publicly available records to revisit the event; they looked at failure details, media coverage, recovery effort, and cost. They also used satellite and ground data to determine the precise causes of those satellite failures. The researchers traced the entire space weather event from conditions on the Sun through the interplanetary medium to the particle environment in geostationary orbit.

Balcerak, Ernie

2012-12-01

56

White matter structural connectivity underlying semantic processing: evidence from brain damaged patients.  

PubMed

Widely distributed brain regions in temporal, parietal and frontal cortex have been found to be involved in semantic processing, but the anatomical connections supporting the semantic system are not well understood. In a group of 76 right-handed brain-damaged patients, we tested the relationship between the integrity of major white matter tracts and the presence of semantic deficits. The integrity of white matter tracts was measured by percentage of lesion voxels obtained in structural imaging and mean fractional anisotropy values obtained in diffusion tensor imaging. Semantic deficits were assessed by jointly considering the performance on three semantic tasks that vary in the modalities of input (visual and auditory stimuli) and output (oral naming and associative judgement). We found that the lesion volume and fractional anisotropy value of the left inferior fronto-occipital fasciculus, left anterior thalamic radiation, and left uncinate fasciculus significantly correlated with severity of impairment in all three semantic tasks. These associations remained significant even when we controlled for a wide range of potential confounding variables, including overall cognitive state, whole lesion volume, or type of brain damage. The effects of these three white matter tracts could not be explained by potential involvement of relevant grey matter, and were (relatively) specific to object semantic processing, as no correlation with performance on non-object semantic control tasks (oral repetition and number processing tasks) was observed. These results underscore the causal role of left inferior fronto-occipital fasciculus, left anterior thalamic radiation, and left uncinate fasciculus in semantic processing, providing direct evidence for (part of) the anatomical skeleton of the semantic network. PMID:23975453

Han, Zaizhu; Ma, Yujun; Gong, Gaolang; He, Yong; Caramazza, Alfonso; Bi, Yanchao

2013-08-23

57

Lateralization of the arcuate fasciculus and its differential correlation with reading ability between young learners and experienced readers: a diffusion tensor tractography study in a Chinese cohort.  

PubMed

As Chinese reading engages a different neural network from alphabetic language reading, we investigate whether leftward lateralization of the arcuate fasciculus (AF), as observed in the Western population, is also present in the Chinese population and if it does, whether it is associated with better reading ability. Diffusion tensor tractography analysis on 75 Chinese subjects of three age groups (first graders, fourth graders, and college students) showed that 70-83% of them had leftward lateralization of the AF. The pattern of lateralization did not differ significantly among the three groups, suggesting that lateralization of the AF is formed at an early age and before one enters first grade. Among the first graders, who had just started to learn to read, subjects with strongly leftward lateralized AF scored significantly higher than those with other defined lateralization patterns in Chinese (P = 0.001) and English (P = 0.036) reading tasks. This association was not observed among the fourth graders and college students who were experienced Chinese readers. Among the fourth graders, females were found to obtain significantly higher Chinese (P = 0.033) and English reading scores than males (P = 0.002). Our study suggests a differential effect of leftward lateralization of the AF on reading ability at different stages of reading development in the Chinese population. PMID:21259386

Qiu, Deqiang; Tan, Li-Hai; Siok, Wai-Ting; Zhou, Ke; Khong, Pek-Lan

2011-01-21

58

Downbeat nystagmus associated with damage to the medial longitudinal fasciculus of the pons: a vestibular balance control mechanism via the lower brainstem paramedian tract neurons.  

PubMed

The paramedian tract (PMT) neurons, a group of neurons associated with eye movement that project into the cerebellar flocculus, are present in or near the medial longitudinal fasciculus (MLF) in the paramedian region of the lower brainstem. A 66-year-old man with multiple sclerosis in whom downbeat nystagmus appeared along with right MLF syndrome due to a unilateral pontomedullary lesion is described. In light of these findings, a possible schema for the vestibular balance control mechanism circuit of the PMT neurons via the flocculus is presented. Damage to the PMT neurons impaired the elective inhibitory control mechanism of the anterior semicircular canal neural pathway by the flocculus. This resulted in the appearance of anterior semicircular canal-dominant vestibular imbalance and the formation of downbeat nystagmus. From the pathogenesis of this vertical vestibular nystagmus, the action of the PMT neurons in the vestibular eye movement neuronal pathway to maintain vestibular balance was conjectured to be as follows. PMT neurons transmit vestibular information from the anterior semicircular canals to the cerebellum, forming a cerebellum/brainstem feedback loop. Vestibular information from that loop is integrated in the cerebellum, inhibiting only the anterior semicircular canal neuronal pathway via the flocculus and controlling vestibular balance. PMID:23510567

Nakamagoe, Kiyotaka; Fujizuka, Natsu; Koganezawa, Tadachika; Yamaguchi, Tetsuto; Tamaoka, Akira

2013-03-16

59

Revisiting learning difficulties in biology  

Microsoft Academic Search

When students from Scottish schools were surveyed 15 years ago about their difficulties in learning biology, two main topic areas stood out as high in perceived difficulty: water transport in plants and genetics. In the interim, curricular changes have been made in which cognisance was taken of these findings. The present study was a revisit to ascertain the changes in

M. Bahar; A. H. Johnstone; M. H. Hansell

1999-01-01

60

Revisiting Rose's common currency debate  

Microsoft Academic Search

The main objective of this research is to revisit the estimation of the effect of a common currency on international trade by applying the new methodology proposed by Helpman, Melitz and Rubistein (2008) and incorporating tourism to the theoretical framework. Rose (2000) estimates an empirical model of bilateral trade, finding a significant coefficient for a currency union variable of 1.2,

María Santana-Gallego; Francisco J. Ledesma-Rodríguez; Jorge V. Pérez-Rodríguez

2010-01-01

61

Hemingway and Gender: Biography Revisited  

Microsoft Academic Search

This article reviews a number of biographies on Hemingway with the aim of revisiting the issue of gender and its relationship to life writing. Since biography has been defined as the best arena in which to fight unexamined assumptions and prejudiced notions, postmodernist biographical research into Hemingway has invariably pursued the explosion of the myth of masculinity by asserting that

Mauricio D. Aguilera Linde

62

The Levy sections theorem revisited  

Microsoft Academic Search

This paper revisits the Levy sections theorem. We extend the scope of the theorem to time series and apply it to historical daily returns of selected dollar exchange rates. The elevated kurtosis usually observed in such series is then explained by their volatility patterns. And the duration of exchange rate pegs explains the extra elevated kurtosis in the exchange rates

Annibal Figueiredo; Iram Gleria; Raul Matsushita; Sergio Da Silva

2007-01-01

63

Dark energy perturbations revisited  

NASA Astrophysics Data System (ADS)

In this Letter we study the evolution of cosmological perturbations in the presence of dynamical dark energy, and revisit the issue of dark energy perturbations. For a generally parameterized equation of state (EoS) such as w(z)=w+wz1+z (for a single fluid or a single scalar field), the dark energy perturbation diverges when its EoS crosses the cosmological constant boundary w=-1. In this Letter we present a method of treating the dark energy perturbations during the crossing of the w=-1 surface by imposing matching conditions which require the induced 3-metric on the hypersurface of w=-1 and its extrinsic curvature to be continuous. These matching conditions have been used widely in the literature to study perturbations in various models of early universe physics, such as Inflation, the Pre-Big-Bang and Ekpyrotic scenarios, and bouncing cosmologies. In all of these cases the EoS undergoes a sudden change. Through a detailed analysis of the matching conditions, we show that ? and ? are continuous on the matching hypersurface. This justifies the method used (Zhao et al., 2005, 2007; Xia et al., 2006, 2008) [1-4] in the numerical calculation and data fitting for the determination of cosmological parameters. We discuss the conditions under which our analysis is applicable.

Li, Mingzhe; Cai, Yifu; Li, Hong; Brandenberger, Robert; Zhang, Xinmin

2011-08-01

64

Searle's"Dualism Revisited"  

SciTech Connect

A recent article in which John Searle claims to refute dualism is examined from a scientific perspective. John Searle begins his recent article 'Dualism Revisited' by stating his belief that the philosophical problem of consciousness has a scientific solution. He then claims to refute dualism. It is therefore appropriate to examine his arguments against dualism from a scientific perspective. Scientific physical theories contain two kinds of descriptions: (1) Descriptions of our empirical findings, expressed in an every-day language that allows us communicate to each other our sensory experiences pertaining to what we have done and what we have learned; and (2) Descriptions of a theoretical model, expressed in a mathematical language that allows us to communicate to each other certain ideas that exist in our mathematical imaginations, and that are believed to represent, within our streams of consciousness, certain aspects of reality that we deem to exist independently of their being perceived by any human observer. These two parts of our scientific description correspond to the two aspects of our general contemporary dualistic understanding of the total reality in which we are imbedded, namely the empirical-mental aspect and the theoretical-physical aspect. The duality question is whether this general dualistic understanding of ourselves should be regarded as false in some important philosophical or scientific sense.

P., Henry

2008-11-20

65

Streaming potential revisited  

NASA Astrophysics Data System (ADS)

Streaming-potential phenomena refer to the generation of bulk electric fields by imposed relative motion between a charged solid and the Debye layer adjacent to it. Realistic scenarios are adequately described by the thin-Debye-layer limit ?->0 (? denoting the dimensionless Debye thickness), which has been addressed by Cox (1997). Cox's analysis has established that the perturbation to the flow, neglected in the earlier investigations, gives rise to an O(4?) force that dominates that contributed by Maxwell stresses. Cox's theory is founded upon the assumption of O(1) Hartmann and P'eclet numbers. We demonstrate that the product of these numbers is actually O(&-2circ;) and accordingly revisit the generic problem of streaming-potential. Electric-current matching between the Debye layer and the bulk provides an inhomogeneous Neumann condition governing the electric field in the latter. This field, in turn, results in a velocity perturbation animated by a Smoluchowski-type slip condition. Owing to dominant convection, the present analysis yields an asymptotic structure considerably simpler than that of Cox (1997): the electro-viscous effect now already appears at O(2?) and is contributed by both Maxwell and viscous stresses. The present paradigm is illustrated for the prototypic problem of a sphere sedimenting in an unbounded fluid, with the resulting drag correction differing from that calculated by Cox (1997).

Yariv, Ehud; Schnitzer, Ory; Frankel, Itzchak

2011-11-01

66

First Grade Writers Revisit Their Work  

ERIC Educational Resources Information Center

|In this article, the author focuses on first grade readers and writers who revisit their work and describes what first-graders do when they revisit their writing about science and literature and review collections of their work. The first-graders discussed here are in Elaine O'Connor's classroom at Clark Elementary School in Charlottesville. In a…

Hansen, Jane A.

2007-01-01

67

Negotiating the People's Capital Revisited  

Microsoft Academic Search

Editor's Note: What follows is the second part of an unofficial transcript of an off-the-record conversation among three of the labor movement's leading strategists. (The first installment appeared under the title “Strategy for Labor,” 22 J. Labor Research 569 (Summer 2001), and has been updated as “Strategy for Labor Revisited,” available www.ssrn.com). This second meeting was also convened by C,

Samuel Estreicher

2011-01-01

68

Secret Public Key Protocols Revisited  

Microsoft Academic Search

Password-based protocols are important and popular means of providing human-to-machine authentication. The concept of secret\\u000a public keys was proposed more than a decade ago as a means of securing password-based authentication protocols against off-line\\u000a password guessing attacks, but was later found vulnerable to various attacks. In this paper, we revisit the concept and introduce\\u000a the notion of identity-based secret public

Hoon Lim; Kenneth Paterson

69

Doppler ultrasound--basics revisited.  

PubMed

Palpation of pedal pulses alone is known to be an unreliable indicator for the presence of arterial disease. Using portable Doppler ultrasound to measure the resting ankle brachial pressure index is superior to palpation of peripheral pulses as an assessment of the adequacy pf the arterial supply in the lower limb. Revisiting basics, this article aims to aid the clinician to understand and perform hand-held Doppler ultrasound effectively while involving the client or patient in the process. The author describes the basics of Doppler ultrasound, how to select correct equipment for the process, and interpretation of results to further enhance clinicians' knowledge. PMID:16835512

Eagle, Mary

70

Simon Gutowitz bidirectional traffic model revisited  

NASA Astrophysics Data System (ADS)

The Simon Gutowitz bidirectional traffic model [P.M. Simon, H.A. Gutowitz, Phys. Rev. E 57 (1998) 2441] is revisited in this Letter. We found that passing cars get stuck with oncoming cars before returning to their home lanes. This provokes the occurrence of wide jams on both lanes. We have rectified the rules for lane changing. Then, the wide jams disappear and the revisited model can describe well the realistic bidirectional traffic.

Moussa, Najem

2008-11-01

71

Acute Kidney Injury: Controversies Revisited  

PubMed Central

This paper addresses the epidemiology of AKI specifically in relation to recent changes in AKI classification and revisits the controversies regarding the timing of initiation of dialysis and the use of peritoneal dialysis as a renal replacement therapy for AKI. In summary, the new RIFLE/AKIN classifications of AKI have facilitated more uniform diagnosis of AKI and clinically significant risk stratification. Regardless, the issue of timing of dialysis initiation still remains unanswered and warrants further examination. Furthermore, peritoneal dialysis as a treatment modality for AKI remains underutilised in spite of potential beneficial effects. Future research should be directed at identifying early reliable biomarkers of AKI, which in conjunction with RIFLE/AKIN classifications of AKI could facilitate well-designed large randomised controlled trials of early versus late initiation of dialysis in AKI. In addition, further studies of peritoneal dialysis in AKI addressing dialysis dose and associated complications are required for this therapy to be accepted more widely by clinicians.

Yong, Kenneth; Dogra, Gursharan; Boudville, Neil; Pinder, Mary; Lim, Wai

2011-01-01

72

The Levy sections theorem revisited  

NASA Astrophysics Data System (ADS)

This paper revisits the Levy sections theorem. We extend the scope of the theorem to time series and apply it to historical daily returns of selected dollar exchange rates. The elevated kurtosis usually observed in such series is then explained by their volatility patterns. And the duration of exchange rate pegs explains the extra elevated kurtosis in the exchange rates of emerging markets. In the end, our extension of the theorem provides an approach that is simpler than the more common explicit modelling of fat tails and dependence. Our main purpose is to build up a technique based on the sections that allows one to artificially remove the fat tails and dependence present in a data set. By analysing data through the lenses of the Levy sections theorem one can find common patterns in otherwise very different data sets.

Figueiredo, Annibal; Gleria, Iram; Matsushita, Raul; Da Silva, Sergio

2007-06-01

73

REVISITING THE PARADIGMS OF INSTRUCTIONAL TECHNOLOGY  

Microsoft Academic Search

In this paper I revisit a previously-pub lished analysis of paradigm shifts within research on instructional technology (IT). Following Kuhn, I will use the term 'paradigm' to denote an actual scientific achievement. Used in this way, a particular experiment or research study must meet two criteria to qualify as a paradigm: it must be novel, that is it must be

Timothy Koschmann

74

"Student Personnel: All Hail and Farewell!" Revisited.  

ERIC Educational Resources Information Center

Revisits Crookston's (1976) article advocating to expunge term "student personnel," arguing that it is inappropriate and no longer descriptive of student affairs. Presents background of term to determine whether it continues to be used to identify chief student affairs officers and graduate programs that prepare sstudent affairs practitioners or…

Bucci, Frank A.

1993-01-01

75

Revisiting the Skills Agenda: A Complicated Geography  

ERIC Educational Resources Information Center

|This paper revisits the skills agenda and suggests that in light of shifts from supply-side to demand-led provision within the UK higher education sector, there is a need to think more critically about the role and place of skills within university curricula. It suggests that if universities are to respond effectively to sector changes, then the…

Saunders, Angharad

2011-01-01

76

Citizenship Education Revisited: Policy, Participation and Problems  

ERIC Educational Resources Information Center

|This article revisits the underlying principles of the citizenship curriculum in England to address reports of communication breakdowns between schools and students and to consider whether the curriculum can do anything other than prescribe what democratic participation should be. Although the focus is on the curriculum in England, it has…

Watts, Michael

2006-01-01

77

Classic performance indexes revisited: axiomatic and applications  

Microsoft Academic Search

In this short article we revisit three classic performance indexes: Sharpe, Treynor and Jensen, adding a fourth index, the Penalized Internal Rate of Return (PIRR), which is perfectly coherent with those three. We propose some axioms that support the logic of these indexes, identifying one exception for the Treynor index and warning about the problems of quotients use. All these

Fernando Gómez-Bezares

2012-01-01

78

Classic performance indexes revisited: axiomatic and applications  

Microsoft Academic Search

In this short article we revisit three classic performance indexes: Sharpe, Treynor and Jensen, adding a fourth index, the Penalized Internal Rate of Return (PIRR), which is perfectly coherent with those three. We propose some axioms that support the logic of these indexes, identifying one exception for the Treynor index and warning about the problems of quotients use. All these

Fernando Gómez-Bezares

2011-01-01

79

The Rotating Morse-Pekeris Oscillator Revisited  

ERIC Educational Resources Information Center

The Morse-Pekeris oscillator model for the calculation of the vibration-rotation energy levels of diatomic molecules is revisited. This model is based on the realization of a second-order exponential expansion of the centrifugal term about the minimum of the vibrational Morse oscillator and the subsequent analytical resolution of the resulting…

Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

2008-01-01

80

Revisiting Fascist Italy's Crime in Ethiopia ? I???? ???  

Microsoft Academic Search

This essay will make a brief historical synopsis and analysis of the crimes perpetrated by the Italian fascists against the Ethiopian people in the 1930s. At this particular juncture, it may sound ironic to revisit the crimes against humanity committed in Ethiopia by Fascist henchmen like Marshall Pietro Badoglio and Marshal Rodolfo Graziani, but sometimes the past contends with the

Ghelawdewos Araia

81

Revisiting link privacy in social networks  

Microsoft Academic Search

In this paper, we revisit the problem of the link privacy attack in online social networks. In the link privacy attack, it turns out that by bribing or compromising a small number of nodes (users) in the social network graph, it is possible to obtain complete link information for a much larger fraction of other non-bribed nodes in the graph.

Suhendry Effendy; Roland H. C. Yap; Felix Halim

2012-01-01

82

Revisiting R-Tree Construction Principles  

Microsoft Academic Search

Spatial indexing is a well researched field that benefited com- puter science with many outstanding results. Our effort in this paper can be seen as revisiting some outstanding contributions to spatial indexing, questioning some paradigms, and designing an access method with glob- ally improved performance characteristics. In particular, we argue that dynamic R-tree construction is a typical clustering problem which

Sotiris Brakatsoulas; Dieter Pfoser; Yannis Theodoridis

2002-01-01

83

Racial bias in baseball card collecting revisited  

Microsoft Academic Search

Although research examining the role of racial bias in the secondary sports card market has been an emerging area of inquiry, empirical knowledge on the question: “Does the race of the player on a sports card affect the value of the card?” remains inconclusive. This paper revisits one of the first studies on this topic. Data were derived for 66

Eric Primm; Nicole L. Piquero; Robert M. Regoli; Alex R. Piquero

2010-01-01

84

The Rotating Morse-Pekeris Oscillator Revisited  

ERIC Educational Resources Information Center

|The Morse-Pekeris oscillator model for the calculation of the vibration-rotation energy levels of diatomic molecules is revisited. This model is based on the realization of a second-order exponential expansion of the centrifugal term about the minimum of the vibrational Morse oscillator and the subsequent analytical resolution of the resulting…

Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

2008-01-01

85

Revisiting the 1999 Cocking Lecture: Asynchronous Partners.  

ERIC Educational Resources Information Center

Revisits the author's lecture and discusses progress in the area of asynchronous learning. The lecture addressed trends in technology in society and education, the changing professoriate, public-private partnerships, and leadership in global education. Some predictions from the lecture proved true; others did not. (Contains eight references.) (WFA)

Papalewis, Rosemary

2002-01-01

86

Revisiting the argument from fetal potential  

Microsoft Academic Search

One of the most famous, and most derided, arguments against the morality of abortion is the argument from potential, which maintains that the fetus' potential to become a person and enjoy the valuable life common to persons, entails that its destruction is prima facie morally impermissible. In this paper, I will revisit and offer a defense of the argument from

Bertha Alvarez Manninen

2007-01-01

87

Transport–Regional Equity Issue Revisited  

Microsoft Academic Search

Almeida E. S. de, Haddad E. A. and Hewings G. J. D. Transport–regional equity issue revisited, Regional Studies. The objective of this paper is to analyse the relationship between transport and regional equity in Minas Gerais, Brazil. Furthermore, the existence of a trade-off between economic performance and regional equity is investigated as well. To do so, the paper develops a

Eduardo Simões de Almeida; Eduardo Amaral Haddad; Geoffrey J. D. Hewings

2010-01-01

88

Revisiting ADOPTing and its Feedback Schemes  

Microsoft Academic Search

Here we revisit ADOPT-ing and bring two new contributions. One contribution consists of developing variations on the algorithms keeping the improvement in length of chain of causal messages without an increase in the total number of messages. While past experiments have shown that sending more feedback is better than sending the minimal information needed for correctness, new experiments show that

Marius C. Silaghi; Makoto Yokoo

2007-01-01

89

Revisiting ADOPTing and its Feedback Schemes  

Microsoft Academic Search

Here we revisit ADOPT-ing and bring two new contribu- tions. One contribution consists of developing variationson the algorithms keeping the improvement in length of chain of causal messages without an increase in the total num- ber of messages. While past experiments have shown that sending more feedback is better than sending the minimal information needed for correctness, new experiments show

Marius-calin Silaghi; Makoto Yokoo

2007-01-01

90

Gate sizing by Lagrangian relaxation revisited  

Microsoft Academic Search

In this paper, we formulate the Generalized Convex Sizing (GCS) problem that unifies and generalizes the sizing problems. We revisit the approach to solve the sizing problem by Lagrangian relaxation, point out several misunderstandings in the previous works, and extend the approach to handle general convex delay functions in the GCS problems. We identify a class of proper GCS problems

Jia Wang; Debasish Das; Hai Zhou

2007-01-01

91

Log-periodic crashes revisited  

NASA Astrophysics Data System (ADS)

We revisit the finding that crashes can be deterministic and governed by log-periodic formulas [D. Sornette, A. Johansen, Significance of log-periodic precursors to financial crashes, Quant. Finance 1 (2001) 452 471; D. Sornette, W.X. Zhou, The US 2000 2002 market descent: how much longer and deeper?, Quant. Finance 2 (2002) 468 481]. One- and two-harmonic equations are usually employed to fit daily data during bubble episodes. But a three-harmonics has been shown to fit anti-bubbles [A. Johansen, D. Sornette, Financial “anti-bubbles”: log-periodicity in gold and Nikkei collapses, Int. J. Mod. Phys. C 10 (1999) 563 575]. Here we show that the three-harmonic formula can work for bubble episodes as well as anti-bubbles. This is illustrated with daily data from the Brazilian real-US dollar exchange rate. And we also show that the three-harmonics can fit an intraday data set from that foreign exchange rate.

Matsushita, Raul; da Silva, Sergio; Figueiredo, Annibal; Gleria, Iram

2006-05-01

92

Pharmacy School Survey Standards Revisited  

PubMed Central

In a series of 3 papers on survey practices published from 2008 to 2009, the editors of the American Journal of Pharmaceutical Education presented guidelines for reporting survey research, and these criteria are reflected in the Author Instructions provided on the Journal’s Web site. This paper discusses the relevance of these criteria for publication of survey research regarding pharmacy colleges and schools. In addition, observations are offered about surveying of small "universes" like that comprised of US colleges and schools of pharmacy. The reason for revisiting this issue is the authors’ concern that, despite the best of intentions, overly constraining publication standards might discourage research on US colleges and schools of pharmacy at a time when the interest in the growth of colleges and schools, curricular content, clinical education, competence at graduation, and other areas is historically high. In the best traditions of academia, the authors share these observations with the community of pharmacy educators in the hope that the publication standards for survey research about US pharmacy schools will encourage investigators to collect and disseminate valuable information.

Barnett, Mitchell J.; Lenth, Russell V.; Knapp, Katherine K.

2013-01-01

93

Revisiting \\  

Microsoft Academic Search

Although numerous advancements have been made in the study of agenda setting among the media, the president, and Congress, scholars have struggled to develop a cohesive theory about who influences whom. To address this problem, I integrate exogenous variables from the American politics and policy literatures into traditional dynamic agenda setting models. In contrast to prior research, which has tended

Ashlie B Delshad

2011-01-01

94

Mean diffusivity and fractional anisotropy as indicators of disease and genetic liability to schizophrenia  

PubMed Central

The goals of this study were to first determine whether the fractional anisotropy (FA) and mean diffusivity (MD) of major white matter pathways associate with schizophrenia, and secondly to characterize the extent to which differences in these metrics might reflect a genetic predisposition to schizophrenia. Differences in FA and MD were identified using a comprehensive atlas-based tract mapping approach using diffusion tensor imaging and high resolution structural data from 35 patients, 28 unaffected first-degree relatives of patients, 29 community controls, and 14 first-degree relatives of controls. Schizophrenia patients had significantly higher MD in the following tracts compared to controls: the right anterior thalamic radiations, the forceps minor, the bilateral inferior fronto-occipital fasciculus (IFO), the temporal component of the left superior longitudinal fasciculus (tSLF), and the bilateral uncinate. FA showed schizophrenia effects and a linear relationship to genetic liability (represented by schizophrenia patients, first-degree relatives, and controls) for the bilateral IFO, the left inferior longitudinal fasciculus (ILF), and the left tSLF. Diffusion tensor imaging studies have previously identified white matter abnormalities in all three of these tracts in schizophrenia; however, this study is the first to identify a significant genetic liability. Thus, FA of these three tracts may serve as biomarkers for studies seeking to identify how genes influence brain structure predisposing to schizophrenia. However, differences in FA and MD in frontal and temporal white matter pathways may be additionally driven by state variables that involve processes associated with the disease.

Clark, Kristi A.; Nuechterlein, Keith H.; Asarnow, Robert F.; Hamilton, Liberty S.; Phillips, Owen R.; Hageman, Nathan S.; Woods, Roger P.; Alger, Jeffry R.; Toga, Arthur W.; Narr, Katherine L.

2011-01-01

95

Effects of aging and calorie restriction on white matter in rhesus macaques.  

PubMed

Rhesus macaques on a calorie restricted diet (CR) develop less age-related disease, have virtually no indication of diabetes, are protected against sarcopenia, and potentially live longer. Beneficial effects of caloric restriction likely include reductions in age-related inflammation and oxidative damage. Oligodendrocytes are particularly susceptible to inflammation and oxidative stress, therefore, we hypothesized that CR would have a beneficial effect on brain white matter and would attenuate age-related decline in this tissue. CR monkeys and controls underwent diffusion tensor imaging (DTI). A beneficial effect of CR indexed by DTI was observed in superior longitudinal fasciculus, fronto-occipital fasciculus, external capsule, and brainstem. Aging effects were observed in several regions, although CR appeared to attenuate age-related alterations in superior longitudinal fasciculus, frontal white matter, external capsule, right parahippocampal white matter, and dorsal occipital bundle. The results, however, were regionally specific and also suggested that CR is not salutary across all white matter. Further evaluation of this unique cohort of elderly primates to mortality will shed light on the ultimate benefits of an adult-onset, moderate CR diet for deferring brain aging. PMID:20541839

Bendlin, B B; Canu, E; Willette, A; Kastman, E K; McLaren, D G; Kosmatka, K J; Xu, G; Field, A S; Colman, R J; Coe, C L; Weindruch, R H; Alexander, A L; Johnson, S C

2010-06-11

96

White Matter Integrity and Behavioral Activation in Healthy Subjects  

PubMed Central

Individual differences in behavioral inhibition and behavioral activation may place certain people at greater risk for neuropsychiatric disorders and engagement in risky behaviors. Therefore, studying the neural correlates of behavioral inhibition and activation may help us understand neural mechanisms underlying risk behaviors in both clinical and non-clinical populations. To investigate, we assessed the relationships between white matter integrity and measures of behavioral inhibition and behavioral activation in 51 healthy participants using diffusion tensor imaging (DTI) and the Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) scale. Scores on the Fun-Seeking subscale of the BAS positively correlated with DTI fractional anisotropy (FA) in the left corona radiata and adjacent superior longitudinal fasciculus, and with mean diffusivity (MD) in the left inferior longitudinal fasciculus and inferior fronto-occipital fasciculus after controlling for age, gender, and education. These findings suggest that the integrity of white matter connecting extensive brain regions implicated in self-control and the processing of rewards and emotions are associated with individual differences in the motivation for seeking and participating in fun and novel experiences.

Xu, Jiansong; Kober, Hedy; Carroll, Kathleen M.; Rounsaville, Bruce J.; Pearlson, Godfrey D.; Potenza, Marc N.

2011-01-01

97

White matter integrity and behavioral activation in healthy subjects.  

PubMed

Individual differences in behavioral inhibition and behavioral activation may place certain people at greater risk for neuropsychiatric disorders and engagement in risky behaviors. Therefore, studying the neural correlates of behavioral inhibition and activation may help us understand neural mechanisms underlying risk behaviors in both clinical and non-clinical populations. To investigate, we assessed the relationships between white matter integrity and measures of behavioral inhibition and behavioral activation in 51 healthy participants using diffusion tensor imaging (DTI) and the Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) scale. Scores on the Fun-Seeking subscale of the BAS positively correlated with DTI fractional anisotropy in the left corona radiata and adjacent superior longitudinal fasciculus, and with mean diffusivity in the left inferior longitudinal fasciculus and inferior fronto-occipital fasciculus after controlling for age, gender, and education. These findings suggest that the integrity of white matter connecting extensive brain regions implicated in self-control and the processing of rewards and emotions are associated with individual differences in the motivation for seeking and participating in fun and novel experiences. PMID:21618658

Xu, Jiansong; Kober, Hedy; Carroll, Kathleen M; Rounsaville, Bruce J; Pearlson, Godfrey D; Potenza, Marc N

2011-05-26

98

Role of Frontotemporal Fiber Tract Integrity in Task-Switching Performance of Healthy Controls and Patients with Temporal Lobe Epilepsy  

PubMed Central

The objective of this study is to investigate the relationships among frontotemporal fiber tract compromise and task-switching performance in healthy controls and patients with temporal lobe epilepsy (TLE). We performed diffusion tensor imaging (DTI) on 30 controls and 32 patients with TLE (15 left TLE). Fractional anisotropy (FA) was calculated for four fiber tracts [uncinate fasciculus (UncF), arcuate fasciculus (ArcF), dorsal cingulum (CING), and inferior fronto-occipital fasciculus (IFOF)]. Participants completed the Trail Making Test-B (TMT-B) and Verbal Fluency Category Switching (VFCS) test. Multivariate analyses of variances (MANOVAs) were performed to investigate group differences in fiber FA and set-shifting performances. Canonical correlations were used to examine the overall patterns of structural-cognitive relationships and were followed by within-group bivariate correlations. We found a significant canonical correlation between fiber FA and task-switching performance. In controls, TMT-B correlated with left IFOF, whereas VFCS correlated with FA of left ArcF and left UncF. These correlations were not significant in patients with TLE. We report significant correlations between frontotemporal fiber tract integrity and set-shifting performance in healthy controls that appear to be absent or attenuated in patients with TLE. These findings suggest a breakdown of typical structure-function relationships in TLE that may reflect aberrant developmental or degenerative processes.

Kucukboyaci, N. Erkut; Girard, H.M.; Hagler, D.J.; Kuperman, J.; Tecoma, E.S.; Iragui, V.J.; Halgren, E.; McDonald, C.R.

2012-01-01

99

Role of frontotemporal fiber tract integrity in task-switching performance of healthy controls and patients with temporal lobe epilepsy.  

PubMed

The objective of this study is to investigate the relationships among frontotemporal fiber tract compromise and task-switching performance in healthy controls and patients with temporal lobe epilepsy (TLE). We performed diffusion tensor imaging (DTI) on 30 controls and 32 patients with TLE (15 left TLE). Fractional anisotropy (FA) was calculated for four fiber tracts [uncinate fasciculus (UncF), arcuate fasciculus (ArcF), dorsal cingulum (CING), and inferior fronto-occipital fasciculus (IFOF)]. Participants completed the Trail Making Test-B (TMT-B) and Verbal Fluency Category Switching (VFCS) test. Multivariate analyses of variances (MANOVAs) were performed to investigate group differences in fiber FA and set-shifting performances. Canonical correlations were used to examine the overall patterns of structural-cognitive relationships and were followed by within-group bivariate correlations. We found a significant canonical correlation between fiber FA and task-switching performance. In controls, TMT-B correlated with left IFOF, whereas VFCS correlated with FA of left ArcF and left UncF. These correlations were not significant in patients with TLE. We report significant correlations between frontotemporal fiber tract integrity and set-shifting performance in healthy controls that appear to be absent or attenuated in patients with TLE. These findings suggest a breakdown of typical structure-function relationships in TLE that may reflect aberrant developmental or degenerative processes. PMID:22014246

Kucukboyaci, N Erkut; Girard, H M; Hagler, D J; Kuperman, J; Tecoma, E S; Iragui, V J; Halgren, E; McDonald, C R

2011-10-12

100

Fiber Dissection and DTI Tractography Study of the Temporo-parietal Fiber Intersection Area.  

PubMed

BACKGROUND:: Lesion studies and recent surgical series report important sequelae when damaging the inferior parietal lobe and posterior temporal lobe. Millions of axons cross through the white matter underlying these cortical areas; however, little is known about the complex organization of these connections. OBJECTIVE:: To analyze the subcortical anatomy of a specific region within the parietal and temporal lobes where seven long-distances tracts intersect, i.e. the temporo-parietal fiber intersection area (TPFIA). METHODS:: Four postmortem human hemispheres were dissected, and four healthy hemispheres were analyzed using DTI-based tractography software. The different tracts that intersect at the posterior temporal and parietal lobes were isolated and the relations with the surrounding structures analyzed. RESULTS:: Seven tracts pass through the TPFIA: horizontal portion of the superior longitudinal fasciculus, arcuate fasciculus, middle longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, optic radiations, and tapetum. The TPFIA was located deep to the angular gyrus, posterior portion of the supramarginal gyrus, and posterior portion of the superior, middle, and inferior temporal gyri. CONCLUSION:: The TPFIA is a critical neural crossroad, as it is traversed by seven white matter tracts that connect multiple areas of the ipsilateral and contralateral hemisphere. It is also a vulnerable part of the network, as a lesion within this area will produce multiple disconnections. This is valuable information when planning a surgical approach through the parieto-temporo-occipital junction. In order to decrease the surgical risks, a detailed DTI tractography reconstruction of the TPFIA should be performed and intraoperative electrical stimulation should be strongly considered. PMID:23037819

Martino, Juan; da Silva-Feritas, Rousinelle; Caballero, Hugo; Marco de Lucas, Enrique; García-Porrero, Juan A; Vázquez-Barquero, Alfonso

2012-10-01

101

Cortex-sparing fiber dissection: an improved method for the study of white matter anatomy in the human brain  

PubMed Central

Classical fiber dissection of post mortem human brains enables us to isolate a fiber tract by removing the cortex and overlying white matter. In the current work, a modification of the dissection methodology is presented that preserves the cortex and the relationships within the brain during all stages of dissection, i.e. ‘cortex-sparing fiber dissection’. Thirty post mortem human hemispheres (15 right side and 15 left side) were dissected using cortex-sparing fiber dissection. Magnetic resonance imaging study of a healthy brain was analyzed using diffusion tensor imaging (DTI)-based tractography software. DTI fiber tract reconstructions were compared with cortex-sparing fiber dissection results. The fibers of the superior longitudinal fasciculus (SLF), inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF) and uncinate fasciculus (UF) were isolated so as to enable identification of their cortical terminations. Two segments of the SLF were identified: first, an indirect and superficial component composed of a horizontal and vertical segment; and second, a direct and deep component or arcuate fasciculus. The IFOF runs within the insula, temporal stem and sagittal stratum, and connects the frontal operculum with the occipital, parietal and temporo-basal cortex. The UF crosses the limen insulae and connects the orbito-frontal gyri with the anterior temporal lobe. Finally, a portion of the ILF was isolated connecting the fusiform gyrus with the occipital gyri. These results indicate that cortex-sparing fiber dissection facilitates study of the 3D anatomy of human brain tracts, enabling the tracing of fibers to their terminations in the cortex. Consequently, it is an important tool for neurosurgical training and neuroanatomical research.

Martino, Juan; De Witt Hamer, Philip C; Vergani, Francesco; Brogna, Christian; de Lucas, Enrique Marco; Vazquez-Barquero, Alfonso; Garcia-Porrero, Juan A; Duffau, Hugues

2011-01-01

102

Angular Momentum of Baryons and Dark Matter Halos Revisited.  

National Technical Information Service (NTIS)

Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamic...

A. Slyz C. Pichon J. Devriendt S. A. Kassin T. Kimm Y. Dubois

2011-01-01

103

Exclusive electroproduction revisited: Treating kinematical effects  

SciTech Connect

Generalized parton distributions of the nucleon are accessed via exclusive leptoproduction of the real photon. While earlier analytical considerations of phenomenological observables were restricted to twist-three accuracy, i.e., taking into account only terms suppressed by a single power of the hard scale, in the present study we revisit this differential cross section within the helicity formalism and restore power-suppressed effects stemming from the process kinematics exactly. We restrict ourselves to the phenomenologically important case of lepton scattering off a longitudinally polarized nucleon, where the photon flips its helicity at most by one unit.

Belitsky, A. V. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Mueller, D. [Institut fuer Theoretische Physik II, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2010-10-01

104

Revisiting sea level and energy budgets  

NASA Astrophysics Data System (ADS)

Various factors contribute to sea level rise, including changing groundwater storage, thermal expansion of the oceans, and melting glaciers and ice sheets. However, studies that add up the observed contributions from these effects have not been able to account for the entire observed sea level rise over the past several decades. To help resolve the discrepancy, Church et al. revisited sea level budgets and considered sea level and Earth's energy budgets together using new and updated estimates of all contributing factors for the past several decades, including a new estimate of groundwater depletion. They were able to account for the entire observed sea level change from 1972 to the present.

Balcerak, Ernie

2011-12-01

105

Sloan Digital Sky Survey Photometric Calibration Revisited  

SciTech Connect

The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

Marriner, John; /Fermilab

2012-06-29

106

Brain connectivity in body dysmorphic disorder compared with controls: a diffusion tensor imaging study.  

PubMed

BACKGROUND: Several neuroimaging studies have investigated brain grey matter in people with body dysmorphic disorder (BDD), showing possible abnormalities in the limbic system, orbitofrontal cortex, caudate nuclei and temporal lobes. This study takes these findings forward by investigating white matter properties in BDD compared with controls using diffusion tensor imaging. It was hypothesized that the BDD sample would have widespread significantly reduced white matter connectivity as characterized by fractional anisotropy (FA). Method A total of 20 participants with BDD and 20 healthy controls matched on age, gender and handedness underwent diffusion tensor imaging. FA, a measure of water diffusion within a voxel, was compared between groups on a voxel-by-voxel basis across the brain using tract-based spatial statistics within the FSL package. RESULTS: Results showed that, compared with healthy controls, BDD patients demonstrated significantly lower FA (p < 0.05) in most major white matter tracts throughout the brain, including in the superior longitudinal fasciculus, inferior fronto-occipital fasciculus and corpus callosum. Lower FA levels could be accounted for by increased radial diffusivity as characterized by eigenvalues 2 and 3. No area of higher FA was found in BDD. CONCLUSIONS: This study provided the first evidence of compromised white matter integrity within BDD patients. This suggests that there are inefficient connections between different brain areas, which may explain the cognitive and emotion regulation deficits within BDD patients. PMID:23473554

Buchanan, B G; Rossell, S L; Maller, J J; Toh, W L; Brennan, S; Castle, D J

2013-03-11

107

White matter microstructure in body dysmorphic disorder and its clinical correlates.  

PubMed

Body dysmorphic disorder (BDD) is characterized by an often-delusional preoccupation with misperceived defects of appearance, causing significant distress and disability. Although previous studies have found functional abnormalities in visual processing, frontostriatal, and limbic systems, no study to date has investigated the microstructure of white matter connecting these systems in BDD. Participants comprised 14 medication-free individuals with BDD and 16 healthy controls who were scanned using diffusion-weighted magnetic resonance imaging (MRI). We utilized probabilistic tractography to reconstruct tracts of interest, and tract-based spatial statistics to investigate whole brain white matter. To estimate white matter microstructure, we used fractional anisotropy (FA), mean diffusivity (MD), and linear and planar anisotropy (c(l) and c(p)). We correlated diffusion measures with clinical measures of symptom severity and poor insight/delusionality. Poor insight negatively correlated with FA and c(l) and positively correlated with MD in the inferior longitudinal fasciculus (ILF) and the forceps major (FM). FA and c(l) were lower in the ILF and the inferior fronto-occipital fasciculus and higher in the FM in the BDD group, but differences were nonsignificant. This is the first diffusion-weighted MR investigation of white matter in BDD. Results suggest a relationship between impairments in insight, a clinically important phenotype, and fiber disorganization in tracts connecting visual with emotion/memory processing systems. PMID:23375265

Feusner, Jamie D; Arienzo, Donatello; Li, Wei; Zhan, Liang; Gadelkarim, Johnson; Thompson, Paul M; Leow, Alex D

2013-02-01

108

Sex differences in white matter development during adolescence: A DTI study  

PubMed Central

Adolescence is a complex transitional period in human development, composing physical maturation, cognitive and social behavioral changes. The objective of this study is to investigate sex differences in white matter development and the associations between intelligence and white matter microstructure in the adolescent brain using diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS). In a cohort of 16 typically-developing adolescents aged 13 to 17 years, longitudinal DTI data were recorded from each subject at two time points that were one year apart. We used TBSS to analyze the diffusion indices including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). Our results suggest that boys (13–18 years) continued to demonstrate white matter maturation, whereas girls appeared to reach mature levels earlier. In addition, we identified significant positive correlations between FA and full-scale intelligence quotient (IQ) in the right inferior fronto-occipital fasciculus when both sexes were looked at together. Only girls showed significant positive correlations between FA and verbal IQ in the left cortico-spinal tract and superior longitudinal fasciculus. The preliminary evidence presented in this study supports that boys and girls have different developmental trajectories in white matter microstructure.

Wang, Yingying; Adamson, Chris; Yuan, Weihong; Altaye, Mekibib; Rajagopal, Akila; Byars, Anna W.; Holland, Scott K.

2012-01-01

109

Decreased white matter integrity before the onset of delusions in patients with Alzheimer's disease: diffusion tensor imaging  

PubMed Central

Background The pathology of delusions in patients with Alzheimer’s disease (AD) associated with white matter (WM) abnormalities is poorly understood. In addition, whether the abnormalities in WM integrity that underlie the delusions develop before the onset of the delusions remains unclear. In this study, we used a diffusion tensor imaging approach to examine the existence of baseline abnormalities in WM integrity in AD patients who developed delusions and AD patients who did not develop delusions. Methods Using the Neuropsychiatric Inventory, we identified patients with AD who exhibit delusions during a 1-year period. All the patients underwent a magnetic resonance imaging (MRI) examination at baseline. We conducted fractional anisotropy using tract-based spatial statistics software and compared the results of AD patients who developed delusions with those who did not develop delusions. Results Compared with the AD patients who did not develop delusions (n = 15), the AD patients who developed delusions (n = 10) exhibited two relatively large clusters and one minimal cluster of significantly lower fractional anisotropy results. The first cluster was located in the left parieto-occipital region and included several fibers: the left inferior longitudinal fasciculus, the inferior fronto-occipital fasciculus, the posterior corona radiate, and the forceps major of the corpus callosum. The second cluster was located on the body of the corpus callosum. A third minimal cluster was located on the superior temporal gyrus white matter. Conclusion Abnormalities in WM integrity involving several fibers may be crucial to the development of delusions in AD patients.

Nakaaki, Shutaro; Sato, Junko; Torii, Katsuyoshi; Oka, Mizuki; Negi, Atsushi; Nakamae, Takashi; Narumoto, Jin; Miyata, Jun; Furukawa, Toshi A; Mimura, Masaru

2013-01-01

110

Emerging Structure-Function Relations in the Developing Face Processing System.  

PubMed

To evaluate emerging structure-function relations in a neural circuit that mediates complex behavior, we investigated age-related differences among cortical regions that support face recognition behavior and the fiber tracts through which they transmit and receive signals using functional neuroimaging and diffusion tensor imaging. In a large sample of human participants (aged 6-23 years), we derived the microstructural and volumetric properties of the inferior longitudinal fasciculus (ILF), the inferior fronto-occipital fasciculus, and control tracts, using independently defined anatomical markers. We also determined the functional characteristics of core face- and place-selective regions that are distributed along the trajectory of the pathways of interest. We observed disproportionately large age-related differences in the volume, fractional anisotropy, and mean and radial, but not axial, diffusivities of the ILF. Critically, these differences in the structural properties of the ILF were tightly and specifically linked with an age-related increase in the size of a key face-selective functional region, the fusiform face area. This dynamic association between emerging structural and functional architecture in the developing brain may provide important clues about the mechanisms by which neural circuits become organized and optimized in the human cortex. PMID:23765156

Suzanne Scherf, K; Thomas, Cibu; Doyle, Jaime; Behrmann, Marlene

2013-06-13

111

Altered Microstructure Within Social-Cognitive Brain Networks During Childhood in Williams Syndrome.  

PubMed

Williams syndrome (WS) is a neurodevelopmental condition caused by a hemizygous deletion of ?26-28 genes on chromosome 7q11.23. WS is associated with a distinctive pattern of social cognition. Accordingly, neuroimaging studies show that WS is associated with structural alterations of key brain regions involved in social cognition during adulthood. However, very little is currently known regarding the neuroanatomical structure of social cognitive brain networks during childhood in WS. This study used diffusion tensor imaging to investigate the structural integrity of a specific set of white matter pathways (inferior fronto-occipital fasciculus [IFOF] and uncinate fasciculus [UF]) and associated brain regions [fusiform gyrus (FG), amygdala, hippocampus, medial orbitofrontal gyrus (MOG)] known to be involved in social cognition in children with WS and a typically developing (TD) control group. Children with WS exhibited higher fractional anisotropy (FA) and axial diffusivity values and lower radial diffusivity and apparent diffusion coefficient (ADC) values within the IFOF and UF, higher FA values within the FG, amygdala, and hippocampus and lower ADC values within the FG and MOG compared to controls. These findings provide evidence that the WS genetic deletion affects the development of key white matter pathways and brain regions important for social cognition. PMID:23709644

Haas, Brian W; Barnea-Goraly, Naama; Sheau, Kristen E; Yamagata, Bun; Ullas, Shruti; Reiss, Allan L

2013-05-24

112

Magnetic resonance imaging correlates of first-episode psychosis in young adult male patients: combined analysis of grey and white matter  

PubMed Central

Background Several patterns of grey and white matter changes have been separately described in young adults with first-episode psychosis. Concomitant investigation of grey and white matter densities in patients with first-episode psychosis without other psychiatric comorbidities that include all relevant imaging markers could provide clues to the neurodevelopmental hypothesis in schizophrenia. Methods We recruited patients with first-episode psychosis diagnosed according to the DSM-IV-TR and matched controls. All participants underwent magnetic resonance imaging (MRI). Voxel-based morphometry (VBM) analysis and mean diffusivity voxel-based analysis (VBA) were used for grey matter data. Fractional anisotropy and axial, radial and mean diffusivity were analyzed using tract-based spatial statistics (TBSS) for white matter data. Results We included 15 patients and 16 controls. The mean diffusivity VBA showed significantly greater mean diffusivity in the first-episode psychosis than in the control group in the lingual gyrus bilaterally, the occipital fusiform gyrus bilaterally, the right lateral occipital gyrus and the right inferior temporal gyrus. Moreover, the TBSS analysis revealed a lower fractional anisotropy in the first-episode psychosis than in the control group in the genu of the corpus callosum, minor forceps, corticospinal tract, right superior longitudinal fasciculus, left middle cerebellar peduncle, left inferior longitudinal fasciculus and the posterior part of the fronto-occipital fasciculus. This analysis also revealed greater radial diffusivity in the first-episode psychosis than in the control group in the right corticospinal tract, right superior longitudinal fasciculus and left middle cerebellar peduncle. Limitations The modest sample size and the absence of women in our series could limit the impact of our results. Conclusion Our results highlight the structural vulnerability of grey matter in posterior areas of the brain among young adult male patients with first-episode psychosis. Moreover, the concomitant greater radial diffusivity within several regions already revealed by the fractional anisotropy analysis supports the idea of a late myelination in patients with first-episode psychosis.

Ruef, Anne; Curtis, Logos; Moy, Guenael; Bessero, Severine; Ba, Maryse Badan; Lazeyras, Francois; Lovblad, Karl-Olof; Haller, Sven; Malafosse, Alain; Giannakopoulos, Panteleimon; Merlo, Marco

2012-01-01

113

Pathogenesis of Progressive Multifocal Leukoencephalopathy--Revisited  

PubMed Central

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system that is rare even though the proven etiological agent of PML, the polyomavirus JC (JC virus), is ubiquitous within the human population. The common feature of PML cases appears to be underlying immunosuppression, and PML has gained clinical visibility because of its association with human immunodeficiency virus and AIDS and its occurrence as a side effect of certain immunomodulatory drugs. A hypothesis has gained general acceptance that JC virus causes a primary infection in childhood and enters a latent state, after which immunosuppression allows viral reactivation leading to PML. Nonetheless, many important aspects of PML pathogenesis remain unclear, including the molecular bases of latency and reactivation, the site(s) of latency, the relationship of archetype and prototype virus and the mode of virus transmission within the body and between individuals. In this review, we will revisit these areas and examine what the available evidence suggests.

White, Martyn K.

2011-01-01

114

L'enfant et les sortilèges revisited.  

PubMed

The author discusses 'L'Enfant et les sortilèges', an opera by Ravel based on a short story by Colette, which traces the trials and tribulations of a young boy whose bad behaviour leads to his being sent to his room, left alone and given only tea and bread until dinner. His progression from anger to persecution and fear, the various defences he employs to protect himself from feeling overwhelmed and his despair are graphically illustrated through words and music. The author considers the opera in relation to Klein's theory of the paranoidschizoid position and the struggle involved in maintaining contact with good objects, externally and internally. Revisiting the opera in light of Meltzer's contribution to psychoanalytic thinking provides a wider perspective in which to explore what he has termed the aesthetic conflict and its place in relation to the depressive position and developmental processes. PMID:11144856

Hindle, D

2000-12-01

115

ALFVEN WAVES IN SHEAR FLOWS REVISITED  

SciTech Connect

We revisit our earlier study of the evolution of an initial propagating Alfven wave in a magnetic-field-aligned flow with a cross-field velocity shear. Our goal is to show how the Alfven wave drives up plasma density fluctuations which might be observed and serve as a signature of the presence of Alfven waves in regions such as the solar corona which are inaccessible to direct observations. Here, we introduce a new initial condition which takes into account the initial distortion of the streamlines by the Alfven wave, and we present new analytical results for the driven waves. We find that the density fluctuations of a properly placed linearly polarized Alfven wave in a shear flow are much smaller than we originally estimated.

Hollweg, Joseph V. [Space Science Center, Morse Hall, University of New Hampshire, Durham, NH 03824 (United States); Kaghashvili, Edisher Kh., E-mail: joe.hollweg@unh.edu [Atmospheric and Environmental Research, Inc., 131 Hartwell Avenue, Lexington, MA 02421 (United States)

2012-01-10

116

Nonlinear Dynamics of Mirror Instability Revisited  

SciTech Connect

A nonlinear dynamics of the mirror modes near the instability threshold is revisited. It is shown that the major saturation is provided by modification of the velocity distribution function in the vicinity of small parallel ion velocities. The final relaxation scenario is based on almost resonant particle interaction with mirror modes. The saturated plasma state can be considered as a magnetic counterpart to electrostatic Bernstein-Greene-Kruskal modes. Our analytical model is verified by relevant numerical simulations. Test particle and PIC simulations indeed show that it is a modification of distribution function at small parallel velocities that results in fading away of free energy driving mirror mode. The physical similarity of the mirror and Weibel instabilities is demonstrated. The multipoint satellite measurements in space plasma can be used to validate a proposed scenario.

Pokhotelov, O. A.; Balikhin, M. A. [Automatic Control Systems Engineering, University of Sheffield, Sheffield (United Kingdom); Sagdeev, R. Z.; Dudnikova, G. I. [Department of Physics, University of Maryland, College Park, Maryland (United States); Fedun, V. N. [Department of Applied Mathematics, University of Sheffield, Sheffield (United Kingdom)

2010-12-14

117

Visser's massive graviton bimetric theory revisited  

NASA Astrophysics Data System (ADS)

A massive gravity theory was proposed by Visser in the late 1990s. This theory, based on a background metric b?? and on an usual dynamical metric g?? has the advantage of being free of ghosts as well as discontinuities present in other massive theories proposed in the past. In the present investigation, the equations of Visser’s theory are revisited with particular care on the related conservation laws. It will be shown that a multiplicative factor is missing in the graviton tensor originally derived by Visser, which has no incidence on the weak field approach but becomes important in the strong field regime when, for instance, cosmological applications are considered. In this case, contrary to some previous claims found in the literature, we conclude that a nonstatic background metric is required in order to obtain a solution able to mimic the ?CDM cosmology.

de Roany, Alain; Chauvineau, Bertrand; de Freitas Pacheco, José A.

2011-10-01

118

Revisiting light neutralino scenarios in the MSSM  

SciTech Connect

We revisit the case of a light neutralino lightest supersymmetric particle in the framework of the minimal supersymmetric standard model. We consider a model with 11 free parameters. We show that all scenarios where the annihilation of light neutralinos rely mainly on the exchange of a light pseudoscalar are excluded by direct detection searches and by Fermi measurements of the {gamma}-flux from dwarf spheroidal galaxies. On the other hand, we find scenarios with light sleptons that satisfy all collider and astroparticle physics constraints. In this case, the lower limit on the lightest supersymmetric particle mass is 12.6 GeV. We discuss briefly how the parameter space of the model could be further probed at the LHC.

Albornoz Vasquez, Daniel; Belanger, Genevieve [LAPTH, U. de Savoie, CNRS, BP 110, 74941 Annecy-Le-Vieux (France); Boehm, Celine [LAPTH, U. de Savoie, CNRS, BP 110, 74941 Annecy-Le-Vieux (France); IPPP, Ogden centre, Durham University (United Kingdom)

2011-11-01

119

Predator-prey interactions, resource depression and patch revisitation  

USGS Publications Warehouse

Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short 'recovery' times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.

Erwin, R.M.

1989-01-01

120

Decay of the neutron deficient {sup 32}Ar, revisited  

SciTech Connect

The aim of this work is to revisit the decay of Argon {sup 32}Ar with special emphasis in the p-{gamma} coincidences. The study was motivated by the increase in granularity and sensitivity of the charged particle detectors and by the high sensitivity and large angular coverage obtained by the use of CLOVER detectors.

Dominguez-Reyes, R.; Borge, M. J. G. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Blank, B.; Matea, I.; Adimi, N. [Centre dEtudes Nucleaires de Bordeaux-Gradignan (CENBG), chemin du Solarium, B.P. 120, 33175 Gradignan, Cedex (France); Thomas, J. C. [Fundamental Physics, Chalmers Univ of Technology, S-41296 Goeteborg (Sweden)

2007-11-30

121

Instructional Efficiency: Revisiting the Original Construct in Educational Research  

ERIC Educational Resources Information Center

|This article revisits Paas and Van Merrienboer's (1993) measure of instructional efficiency, which can be applied by educational researchers to compare the effects of different instructional conditions on learning. This measure relied on performance and mental effort on the test, and as such gave an indication of the quality of learning outcomes.…

van Gog, Tamara; Paas, Fred

2008-01-01

122

Revisiting the Revolving Door: Capital Flight from Southeast Asia  

Microsoft Academic Search

The paper revisits hypothesized direct linkages between external borrowing and capital flight. It reviews the cases of Indonesia, Malaysia, the Philippines and Thailand to see if such linkages exist. The results indicate that, indeed, large sums of capital flowed in and out of these four countries in a revolving door process. Thus, the results lend support to the need for:

Edsel L. Beja Jr.

2006-01-01

123

Moral Judgment Development across Cultures: Revisiting Kohlberg's Universality Claims  

ERIC Educational Resources Information Center

|This article revisits Kohlberg's cognitive developmental claims that stages of moral judgment, facilitative processes of social perspective-taking, and moral values are commonly identifiable across cultures. Snarey [Snarey, J. (1985). "The cross-cultural universality of social-moral development: A critical review of Kohlbergian research."…

Gibbs, John C.; Basinger, Karen S.; Grime, Rebecca L.; Snarey, John R.

2007-01-01

124

Literary Origins of the Term "School Psychologist" Revisited  

ERIC Educational Resources Information Center

|Previous research on the literary origins of the term "school psychologist" is revisited, and conclusions are revised in light of new evidence. It appears that the origin of the term in the American literature occurred as early as 1898 in an article by Hugo Munsterberg, predating the usage by Wilhelm Stern in 1911. The early references to the…

Fagan, Thomas K.

2005-01-01

125

Educational Administration and the Management of Knowledge: 1980 Revisited  

ERIC Educational Resources Information Center

|This paper revisits the thesis of a 1980 paper that suggested a new approach to educational administration based upon the New Sociology of Education. In particular it updates answers to the six key questions asked by that paper: what counts as knowledge; how is what counts as knowledge organised; how is what counts as knowledge transmitted; how…

Bates, Richard

2013-01-01

126

Antidote for Zero Tolerance: Revisiting a "Reclaiming" School.  

ERIC Educational Resources Information Center

Reports on a revisit to the Frank Lloyd Wright Middle School, which implemented strategies to deal with disciplinary problems. The school continues to progress towards creating the type of reclaiming environment necessary to ensure the needs of all students. Strategies used include alternatives to zero tolerance policy; smaller teams of students;…

Farner, Conrad D.

2002-01-01

127

Magnetic Braking Revisited: Activities for the Undergraduate Laboratory  

ERIC Educational Resources Information Center

|This paper revisits the demonstration of Lenz by dropping magnets down a non-magnetic tube. Recent publications are reviewed and ideas for undergraduate laboratory investigations are suggested. Finally, an example of matching theory to observation is presented. (Contains 4 tables, 5 figures and 3 footnotes.)|

Ireson, Gren; Twidle, John

2008-01-01

128

The relationship between economic development and business ownership revisited  

Microsoft Academic Search

This paper revisits the two-equation model of Carree, van Stel, Thurik and Wennekers (2002) where deviations from the ‘equilibrium’ rate of business ownership play a central role in determining both the growth of business ownership and that of economic development. Two extensions of the original set-up are addressed: using longer time series of averaged data of 23 OECD countries (up

Martin Carree; André Van Stel; Roy Thurik; Sander Wennekers

2007-01-01

129

Processing of FORMOSAT-2 Daily Revisit Imagery for Site Surveillance  

Microsoft Academic Search

The successful operation of FORMOSAT-2, which was launched on May 21, 2004, proved the concept that the temporal resolution of a remote sensing system can be much improved by deploying a high spatial resolution sensor in a daily revisit orbit, and each accessible scene can be systematically observed from the same angle under similar illumination conditions. These characteristics make FORMOSAT-2

Cheng-Chien Liu

2006-01-01

130

Revisiting Jack Goody to Rethink Determinisms in Literacy Studies  

ERIC Educational Resources Information Center

|This article revisits Goody's arguments about literacy's influence on social arrangements, culture, cognition, economics, and other domains of existence. Whereas some of his arguments tend toward technological determinism (i.e., literacy causes change in the world), other of his arguments construe literacy as a force that shapes and is shaped by…

Collin, Ross

2013-01-01

131

Girl Number 20 Revisited: Feminist Literacies in New Hard Times  

ERIC Educational Resources Information Center

This paper revisits the question of "voice" in the context of neo-liberal social and educational reform. "Voice" has been one of the key concepts of feminist and critical pedagogies in the theory and practice of producing social transformation. I argue in this paper, that the political effectiveness of this concept needs to be reconsidered at a…

Gonick, Marnina

2007-01-01

132

Revisiting methodological issues in transcript analysis: Negotiated coding and reliability  

Microsoft Academic Search

Transcript analysis is an important methodology to study asynchronous online educational discourse. The purpose of this study is to revisit reliability and validity issues associated with transcript analysis. The goal is to provide researchers with guidance in coding transcripts. For validity reasons, it is suggested that the first step is to select a sound theoretical model and coding scheme. Particular

D. R. Garrison; M. Cleveland-Innes; Marguerite Koole; James Kappelman

2006-01-01

133

Revisiting the Role of Communication in Adolescent Intimate Partner Violence  

ERIC Educational Resources Information Center

A growing literature suggests that communication strategies can promote or inhibit intimate partner violence (IPV). Research on communication is still needed on a group ripe for early IPV intervention: high school-aged adolescents. This article revisits our previous analyses of young female reproductive clinic patients (Messinger, Davidson, &…

Messinger, Adam M.; Rickert, Vaughn I.; Fry, Deborah A.; Lessel, Harriet; Davidson, Leslie L.

2012-01-01

134

China in 2005 Revisited: The Implications of International Capital Mobility  

Microsoft Academic Search

This paper revisits the analysis of the implications of China's economic growth on her trading partners presented in Arndt et al. (1997) using a dynamic, applied general equilibrium model that features international capital mobility. We find that accounting for the impact of China's growth on international capital markets reverses some of the findings in the paper by Arndt et al.

Elena Ianchovichina; Robert McDougall; Thomas W. Hertel

2000-01-01

135

Revisiting Hirschman on Development Assistance and Unbalanced Growth  

Microsoft Academic Search

It is useful from time to time to revisit the pioneers in a field. The richness of their original thought is often diminished as new specialists in a field are educated or, rather, trained. Stylized caricatures and toy models out-compete nuanced multidisciplinary narratives in the competition for shelf-space in textbooks. After the students ingest the textbooks and go forth in

David Ellerman

2004-01-01

136

Revisiting the uniqueness of simple demographics in the US population  

Microsoft Academic Search

According to a famous study (10) of the 1990 census data, 87% of the US population can be uniquely identified by gen- der, ZIP code and full date of birth. This short paper revisits the uniqueness of simple demographics in the US population based on the most recent census data (the 2000 census). We oer a detailed, comprehensive and up-to-date

Philippe Golle

2006-01-01

137

Practical historians and adversaries: 9\\/11 revisited  

Microsoft Academic Search

This article extends the idea of ‘structured immediacy’ (Leudar et al., 2008b) by investigating methods that adversaries use to make the past relevant and consequential in conflicts. Our strategy was to revisit our analysis of political discourse immediately following the 9\\/11 attacks in the USA (Leudar et al., 2004; Leudar and Nekvapil, 2007). We did this to document what the

Ivan Leudar; Ji?í Nekvapil

2011-01-01

138

Critical natural capital revisited: Ecological resilience and sustainable development  

Microsoft Academic Search

The maintenance of critical natural capital is an important objective of sustainable development. Critical natural capital represents a multidimensional concept, as it mirrors the different frameworks of various scientific disciplines and social groups in valuing nature. This article revisits the concept of critical natural capital and examines its relation to the concept of ecological resilience. I propose that ecological resilience

Fridolin Brand

2009-01-01

139

Revisiting youthful sexuality: continuities and changes over two decades  

Microsoft Academic Search

In this short article we revisit “Deconstructing virginity” published in Sex and Relationship Therapy in 2000. The article was based on data from two largely qualitative studies of young people's sexuality: the Women Risk and AIDS project and subsequent Men, Risk and AIDS project, which were funded in the late-1980s in the light of the threat of HIV and AIDS.

Janet Holland; Rachel Thomson

2010-01-01

140

Financial Openness and Thresholds Revisited: Accounting for Model Uncertainty  

Microsoft Academic Search

Recent research stresses the importance of supportive initial conditions for countries to reap the benefits of financial integration. This paper revisits the robustness and relative importance of different thresholds in the link between financial openness and growth. It offers a comprehensive analysis of threshold effects in a common empirical framework. We employ Bayesian Model Averaging (BMA) techniques to appropriately account

Oliver Röhn

141

Environmental Education and Politics: Snakes and Ladders Revisited  

ERIC Educational Resources Information Center

|This paper revisits the history of environmental education in Australia in the 1970s and 1980s and draws parallels between these and current events in four countries, including Australia. It is argued that little has changed and that few environmental educators confront the inherently political nature of their work. It is concluded that…

Chapman, David

2004-01-01

142

A Truly Early Starter Model of Antisocial Behavior Revisited  

Microsoft Academic Search

This paper revisits a developmental model of the origins of early conduct problems. Several of the model's primary tenets have now been validated in two samples of at-risk children followed prospectively from infancy to school-age. In both cohorts, child, family, and sociodemographic factors all play a significant role in the development of early conduct problems. In particular, the quality of

Daniel S. Shaw; Richard Q. Bell; Miles Gilliom

2000-01-01

143

Revisiting library mission statements in the era of technology  

Microsoft Academic Search

Collection building in today’s technologically rich library environment should include library mission statements that embody all types of formats. It has become the role of the librarian to revisit mission statements and collection development policies periodically and examine the contents for the latest in technology. All library resources formats should be encompassed in the statements developed. The library mission statement

Karen Svenningsen; Lois Cherepon

1998-01-01

144

Gerogogy in patient education--revisited.  

PubMed

Gerogogy in Patient Education was first printed in Home Healthcare Nurse, Volume 14, Number 8, (1996), Lippincott. Writers Mary Pearson, M.Ed, RN- BC and Joan Wessman, MA. have revisited and updated the material to meet the needs of a new generation of health care professionals. Baby Boomers are retiring; they will reach their peak in 2030, with an estimated 72 million drawing social security. With these numbers comes an increase in services to the elderly, mostly in the form of medical expenditure. The problem will not only impact the financial system of Medicare but will have a great toll on families. How will the retirees remain independent in their homes? How will they learn new medical information? Will new health care professions be able to teach them while taking into consideration the physical and psychological alterations that occur with aging and illness? Gerogogy takes into account the person's disease process, age-related changes, educational level and motivation. Then incorporates these factors into practice, utilizing the same foundations found within the nursing process: assessment, planning, implementation, and evaluation. As stated, the methods for teaching the elderly are unique and require modifications. Gerogogy meets these needs so individuals can remain at home while also reducing unnecessary medical costs. PMID:21874787

Pearson, Mary

145

Revisiting the argument from fetal potential.  

PubMed

One of the most famous, and most derided, arguments against the morality of abortion is the argument from potential, which maintains that the fetus' potential to become a person and enjoy the valuable life common to persons, entails that its destruction is prima facie morally impermissible. In this paper, I will revisit and offer a defense of the argument from potential.First, I will criticize the classical arguments proffered against the importance of fetal potential, specifically the arguments put forth by philosophers Peter Singer and David Boonin, by carefully unpacking the claims made in these arguments and illustrating why they are flawed.Secondly, I will maintain that fetal potential is morally relevant when it comes to the morality of abortion, but that it must be accorded a proper place in the argument. This proper place, however, cannot be found until we first answer a very important and complex question: we must first address the issue of personal identity, and when the fetus becomes the type of being who is relevantly identical to a future person. I will illustrate why the question of fetal potential can only be meaningfully addressed after we have first answered the question of personal identity and how it relates to the human fetus. PMID:17509146

Manninen, Bertha Alvarez

2007-05-17

146

White matter integrity, language, and childhood onset schizophrenia  

PubMed Central

Background The heterogeneity of symptoms and cognitive deficits in schizophrenia can be explained by abnormal connectivity between brain regions. Childhood-onset schizophrenia (COS) is a particularly severe form of schizophrenia, with an onset during a key time period for both cerebral pruning and myelination. Methods Diffusion tensor images were acquired from 18 children and adolescents with COS and 25 controls. The COS group was divided into two sub-groups--one with linguistic impairment (LI) and the other without (NLI). The fractional anisotropy (FA), axial (AD), and radial diffusivity (RD) data from the two COS sub-groups were compared to each other and to the controls using tract-based spatial statistics (TBSS) analyses, which is a voxel-based method used to identify regions of white matter abnormalities. Results TBSS identified several regions in the left hemisphere where the LI group had increased AD and RD relative to the NLI and the control groups. These areas primarily localized to linguistic tracts: left superior longitudinal fasciculus and left inferior longitudinal fasciculus/inferior fronto-occipital fasciculus. Regions of increased RD overlapped regions of increased AD, with the former showing more pronounced effects. Conclusions Studies of adult-onset schizophrenia typically identify areas of higher RD but unchanged AD; however, normal development studies have shown that while RD decreases are pronounced over this age range, smaller decreases in AD can also be detected. The observed increases in both RD and AD suggest that developmental disturbances affecting the structural connectivity of these pathways are more severe in COS accompanied by severe linguistic impairments.

Clark, Kristi; Narr, Katherine L.; O'Neill, Joseph; Levitt, Jennifer; Siddarth, Prabha; Phillips, Owen; Toga, Arthur; Caplan, Rochelle

2012-01-01

147

Revisited nitrogen isotopic ratio in molecular clouds  

NASA Astrophysics Data System (ADS)

Fundamental for the understanding of nucleosynthesis processes as well as galactic and solar system evolution, the nitrogen isotope ratio in the galaxy has long been a puzzle. Particularly, meteorites, comets and IDPs show a strong enhancement of the 15N isotope compared to values estimated from molecular clouds, which casts doubts on the pristine nature of the cometary and meteoritic material. Due to high optical depths of the main nitrogen carriers, direct measurement of [14N/15N] is difficult. To date only a few global studies of the nitrogen isotope ratio in dense molecular clouds exist, which employ indirect methods to estimate this ratio. We revisit the nitrogen isotope ratio in dense molecular clouds using two nitrogen carriers, HNC and CN, and several methods. The J=1-0 and 3-2 transitions of HNC at 90 and 271 GHz, and H15NC at 88 and 266 GHz were observed at the Arizona Radio Observatory (ARO) 12m and SMT telescopes, toward the clouds SgrB2, W31, G34.3, W51M, M17-SW, DR-21, Orion A, W3(OH), NGC7538 and S156, located at various galactic distances from the Galactic Center. HNC being optically thick, its abundance was estimated using known [12C/13C] ratios, as well as radiative transfer modeling using the freely available code RADEX. Finally, the N=1-0 transition of CN and C15N at 113 and 110 GHz were also recorded at the 12m telescope. The last and most direct estimation method makes use of the intensities of CN hyperfines to estimate an optical depth and abundance for the main isotope. Results seem to indicate a [14N/15N] ratio of about ˜ 100-350, lower than previously reported, and more in line with cometary or meteoritic values.

Adande, G.; Ziurys, L.

2011-05-01

148

Autosomal recessive cutis laxa syndrome revisited  

PubMed Central

The clinical spectrum of the autosomal recessive cutis laxa syndromes is highly heterogeneous with respect to organ involvement and severity. One of the major diagnostic criteria is to detect abnormal elastin fibers. In several other clinically similar autosomal recessive syndromes, however, the classic histological anomalies are absent, and the definite diagnosis remains uncertain. In cutis laxa patients mutations have been demonstrated in elastin or fibulin genes, but in the majority of patients the underlying genetic etiology remains unknown. Recently, we found mutations in the ATP6V0A2 gene in families with autosomal recessive cutis laxa. This genetic defect is associated with abnormal glycosylation leading to a distinct combined disorder of the biosynthesis of N- and O-linked glycans. Interestingly, similar mutations have been found in patients with wrinkly skin syndrome, without the presence of severe skin symptoms of elastin deficiency. These findings suggest that the cutis laxa and wrinkly skin syndromes are phenotypic variants of the same disorder. Interestingly many phenotypically similar patients carry no mutations in the ATP6V0A2 gene. The variable presence of protein glycosylation abnormalities in the diverse clinical forms of the wrinkled skin-cutis laxa syndrome spectrum necessitates revisiting the diagnostic criteria to be able to offer adequate prognosis assessment and counseling. This paper aims at describing the spectrum of clinical features of the various forms of autosomal recessive cutis laxa syndromes. Based on the recently unraveled novel genetic entity we also review the genetic aspects in cutis laxa syndromes including genotype–phenotype correlations and suggest a practical diagnostic approach.

Morava, Eva; Guillard, Mailys; Lefeber, Dirk J; Wevers, Ron A

2009-01-01

149

Unwarranted Return: A Response to McVee, Dunsmore, and Gavelek's (2005) "Schema Theory Revisited"  

ERIC Educational Resources Information Center

This article presents the authors' response to McVee, Dunsmore, and Gavelek's "Schema Theory Revisited." In "Schema Theory Revisited," McVee, Dunsmore, and Gavelek (2005) proposed a rearticulation of schema theory intended to encompass the ideas that schemata and other cognitive processes are embodied, that knowledge is situated in the transaction…

Krasny, Karen A.; Sadoski, Mark; Paivio, Allan

2007-01-01

150

Unwarranted Return: A Response to McVee, Dunsmore, and Gavelek's (2005) "Schema Theory Revisited"  

ERIC Educational Resources Information Center

|This article presents the authors' response to McVee, Dunsmore, and Gavelek's "Schema Theory Revisited." In "Schema Theory Revisited," McVee, Dunsmore, and Gavelek (2005) proposed a rearticulation of schema theory intended to encompass the ideas that schemata and other cognitive processes are embodied, that knowledge is situated in the…

Krasny, Karen A.; Sadoski, Mark; Paivio, Allan

2007-01-01

151

Symbols and Dynamics in Embodied Cognition: Revisiting a Robot Experiment  

Microsoft Academic Search

\\u000a This paper introduces novel analyses that clarify why the dynamical systems approach is essential for studies of embodied\\u000a cognition by revisiting author’s prior robot experiment studies. Firstly, we argue that the symbol grounding problems as well\\u000a as the “situatedness” problems should be the consequences of lacking a shared metric space for the interactions between the\\u000a higher cognitive levels based on

Jun Tani

2003-01-01

152

Topological Twisted Sigma Model with H-flux Revisited  

SciTech Connect

In this paper we revisit the topological twisted sigma model with H-flux. We explicitly expand and then twist the worldsheet Lagrangian for bi-Hermitian geometry. we show that the resulting action consists of a BRST exact term and pullback terms, which only depend on one of the two generalized complex structures and the B-field. We then discuss the topological feature of the model.

Chuang, Wu-yen

2006-08-18

153

Indoor air and human health revisited: A recent IAQ symposium  

SciTech Connect

Indoor Air and Human Health Revisited was a speciality symposium examining the scientific underpinnings of sensory and sensitivity effects, allergy and respiratory disease, neurotoxicity and cancer. An organizing committee selected four persons to chain the sessions and invite experts to give state-of-the-art presentations that will be published as a book. A summary of the presentations is made and some critical issues identified.

Gammage, R.B.

1994-12-31

154

Distant future of the Sun and Earth revisited  

Microsoft Academic Search

We revisit the distant future of the Sun and the solar system, based on\\u000astellar models computed with a thoroughly tested evolution code. For the solar\\u000agiant stages, mass-loss by the cool (but not dust-driven) wind is considered in\\u000adetail. Using the new and well-calibrated mass-loss formula of Schroder & Cuntz\\u000a(2005, 2007), we find that the mass lost by

Klaus-Peter Schroder; Robert Connon Smith

2008-01-01

155

Distant future of the Sun and Earth revisited  

Microsoft Academic Search

We revisit the distant future of the Sun and the Solar system, based on stellar models computed with a thoroughly tested evolution code. For the solar giant stages, mass loss by the cool (but not dust-driven) wind is considered in detail. Using the new and well-calibrated mass-loss formula of Schröder & Cuntz, we find that the mass lost by the

K.-P. Schröder; Robert Connon Smith

2008-01-01

156

Revisiting the Two-Stage Algorithm for Hammerstein system identification  

Microsoft Academic Search

The Two-Stage Algorithm (TSA) has been extensively used and adapted for the identification of block-oriented nonlinear systems including Hammerstein systems. This paper revisits an optimality result established by Bai in 1998 showing that the TSA provides the optimal estimation of a bilinearly parameterized Hammerstein system in the sense of a weighted nonlinear least-squares (LS) criterion formulated with some special weighting

Jiandong Wang; Qinghua Zhang; LLennart. Ljung

2009-01-01

157

BDNF GENE EFFECTS ON BRAIN CIRCUITRY REPLICATED IN 455 TWINS  

PubMed Central

Brain-derived neurotrophic factor (BDNF) plays a key role in learning and memory, but its effects on the fiber architecture of the living brain are unknown. We genotyped 455 healthy adult twins and their non-twin siblings (188 males/267 females; age: 23.7±2.1 years, mean±SD) and scanned them with high angular resolution diffusion tensor imaging (DTI), to assess how the BDNF Val66Met polymorphism affects white matter microstructure. By applying genetic association analysis to every 3D point in the brain images, we found that the Val-BDNF genetic variant was associated with lower white matter integrity in the splenium of the corpus callosum, left optic radiation, inferior fronto-occipital fasciculus, and superior corona radiata. Normal BDNF variation influenced the association between subjects’ performance intellectual ability (as measured by Object Assembly subtest) and fiber integrity (as measured by fractional anisotropy; FA) in the callosal splenium, and pons. The BDNF gene may affect intellectual performance by modulating white matter development. This combination of genetic association analysis and large-scale diffusion imaging directly relates a specific gene to the fiber microstructure of the living brain and to human intelligence.

Chiang, Ming-Chang; Barysheva, Marina; Toga, Arthur W.; Medland, Sarah E.; Hansell, Narelle K.; James, Michael R.; McMahon, Katie L.; de Zubicaray, Greig I.; Martin, Nicholas G.; Wright, Margaret J.; Thompson, Paul M.

2011-01-01

158

White matter integrity and vulnerability to Alzheimer's disease: Preliminary findings and future directions  

PubMed Central

Neuroimaging biomarkers that precede cognitive decline have the potential to aid early diagnosis of Alzheimer's disease (AD). A body of diffusion tensor imaging (DTI) work has demonstrated declines in white matter (WM) microstructure in AD and its typical prodromal state, amnestic mild cognitive impairment. The present review summarizes recent evidence suggesting that WM integrity declines are present in individuals at high AD-risk, prior to cognitive decline. The available data suggest that AD-risk is associated with WM integrity declines in a subset of tracts showing decline in symptomatic AD. Specifically, AD-risk has been associated with WM integrity declines in tracts that connect grey matter structures associated with memory function. These tracts include parahippocampal WM, the cinglum, the inferior fronto-occipital fasciculus, and the splenium of the corpus callosum. Preliminary evidence suggests that some AD-risk declines are characterized by increases of radial diffusivity, raising the possibility that a myelin-related pathology may contribute to AD onset. These findings justify future research aimed at a more complete understanding of the neurobiological bases of DTI-based declines in AD. With continued refinement of imaging methods, DTI holds promise as a method to aid identification of presymptomatic AD.

Gold, Brian T.; Johnson, Nathan F.; Powell, David K.; Smith, Charles D.

2011-01-01

159

BDNF gene effects on brain circuitry replicated in 455 twins.  

PubMed

Brain-derived neurotrophic factor (BDNF) plays a key role in learning and memory, but its effects on the fiber architecture of the living brain are unknown. We genotyped 455 healthy adult twins and their non-twin siblings (188 males/267 females; age: 23.7±2.1 years, mean±SD) and scanned them with high angular resolution diffusion tensor imaging (DTI), to assess how the BDNF Val66Met polymorphism affects white matter microstructure. By applying genetic association analysis to every 3D point in the brain images, we found that the Val-BDNF genetic variant was associated with lower white matter integrity in the splenium of the corpus callosum, left optic radiation, inferior fronto-occipital fasciculus, and superior corona radiata. Normal BDNF variation influenced the association between subjects' performance intellectual ability (as measured by Object Assembly subtest) and fiber integrity (as measured by fractional anisotropy; FA) in the callosal splenium, and pons. BDNF gene may affect the intellectual performance by modulating the white matter development. This combination of genetic association analysis and large-scale diffusion imaging directly relates a specific gene to the fiber microstructure of the living brain and to human intelligence. PMID:21195196

Chiang, Ming-Chang; Barysheva, Marina; Toga, Arthur W; Medland, Sarah E; Hansell, Narelle K; James, Michael R; McMahon, Katie L; de Zubicaray, Greig I; Martin, Nicholas G; Wright, Margaret J; Thompson, Paul M

2010-12-30

160

Sex-linked white matter microstructure of the social and analytic brain.  

PubMed

Sexual dimorphism in the brain is known to underpin sex differences in neuropsychological behaviors. The white matter (WM) microstructure appears to be coupled with cognitive performances. However, the issues concerning sex differences in WM remains to be determined. This study used the tract-based spatial statistics on diffusion tensor imaging concurrently with the assessments of Empathizing Quotient (EQ) and Systemizing Quotient (SQ) in forty healthy female and forty male adults. Females exhibited greater fractional anisotropy (FA) in the fronto-occipital fasciculus, body of the corpus callosum, and WM underlying the parahippocampal gyrus. Males exhibited larger FA in the bilateral internal capsule, WM underlying the medial frontal gyrus, fusiform gyrus, hippocampus, insula, postcentral gyrus, frontal and temporal lobe. Interestingly, the interaction analysis of dispositional measures by sex showed that females had a positive correlation between FA of the WM underlying the inferior parietal lobule and superior temporal gyrus and EQ but a negative correlation between FA of the occipital and postcentral gyrus and SQ. Males displayed the opposite effect. The findings indicate a sexual dimorphism of WM microstructure. Divergent correlations of WM microstructure and neuropsychological behaviors between sexes may account for the higher prevalence of autism spectrum disorders in males. PMID:20633662

Chou, Kun-Hsien; Cheng, Yawei; Chen, I-Yun; Lin, Ching-Po; Chu, Woei-Chyn

2010-07-12

161

Covert face recognition without the fusiform-temporal pathways.  

PubMed

Patients with prosopagnosia are unable to recognize faces consciously, but when tested indirectly they can reveal residual identification abilities. The neural circuitry underlying this covert recognition is still unknown. One candidate for this function is the partial survival of a pathway linking the fusiform face area (FFA) and anterior-inferior temporal (AIT) cortex, which has been shown to be essential for conscious face identification. Here we performed functional magnetic, and diffusion tensor imaging in FE, a patient with severe prosopagnosia, with the goal of identifying the neural substrates of his robust covert face recognition. FE presented massive bilateral lesions in the fusiform gyri that eliminated both FFAs, and also disrupted the fibers within the inferior longitudinal fasciculi that link the visual areas with the AITs and medial temporal lobes. Therefore participation of the fusiform-temporal pathway in his covert recognition was precluded. However, face-selective activations were found bilaterally in his occipital gyri and in his extended face system (posterior cingulate and orbitofrontal areas), the latter with larger responses for previously-known faces than for faces of strangers. In the right hemisphere, these surviving face selective-areas were connected via a partially persevered inferior fronto-occipital fasciculus. This suggests an alternative occipito-frontal pathway, absent from current models of face processing, that could explain the patient's covert recognition while also playing a role in unconscious processing during normal cognition. PMID:21570471

Valdés-Sosa, Mitchell; Bobes, Maria A; Quiñones, Ileana; Garcia, Lorna; Valdes-Hernandez, Pedro A; Iturria, Yasser; Melie-Garcia, Lester; Lopera, Francisco; Asencio, José

2011-05-04

162

Regulatory T Cells for Tolerance Therapy: Revisiting the Concept  

PubMed Central

The discovery of regulatory T cells (Tregs) as a crucial component of peripheral down-regulation of immunity to self and allogeneic antigens, has raised legitimate hope for the development of Treg-based clinical protocols for tolerance to allografts. The present review addresses the question of whether or not therapeutic Tregs are ready to enter the clinical transplantation arena. In the light of recent experimental observations, we will revisit some fundamentals of T cell and biology that stress the need for further studies prior to applications and provide conceptual cues for novel therapeutic approaches.

LeGuern, Christian

2011-01-01

163

Lost siblings of the Sun: Revisiting the FGK potential candidates  

NASA Astrophysics Data System (ADS)

The main goal of this paper is to revisit the lost siblings of the Sun candidates within 100 pc. The solar siblings should have some similar characteristics as their ages, chemical compositions and kinematics properties. Considering their chemical compositions, age and kinematics properties only three potential candidates have been found in the literature: HD28676, HD83423 and HD175740. The first two stars are mentioned by Brown et al. (2010) and Bobylev et al. (2011), respectively. HD175740 is, to our knowledge, the first giant to be proposed as potential candidate.

Batista, Sérgio Filipe Assunção; Fernandes, João

2012-07-01

164

Revisiting and Computing Reaction Coordinates with Directional Milestoning  

PubMed Central

The method of Directional Milestoning is revisited. We start from an exact and more general expression and state the conditions and validity of the memory-loss approximation. An algorithm to compute a reaction coordinate from Directional Milestoning data is presented. The reaction coordinate is calculated as a set of discrete jumps between Milestones that maximizes the flux between two stable states. As an application we consider a conformational transition in solvated Adenosine. We compare a long molecular dynamic trajectory with Directional Milestoning and discuss the differences between the maximum flux path and minimum energy coordinates.

Kirmizialtin, Serdal; Elber, Ron

2011-01-01

165

Revisiting a Constructive Classic: Wright's Physical Disability: A Psychosocial Approach  

PubMed Central

Beatrice A. Wright's (1960) classic book, Physical Disability: A Psychological Approach is a landmark publication in rehabilitation psychology. The authors believe that Division 22's forthcoming 50th anniversary, the results of a recent survey on essential readings in rehabilitation psychology, and a public critique concerning the relevance of individuating language in psychology are compelling reasons for revisiting the influence of Physical Disability. After discussing these catalysts, the authors review the book's history, scholarly impact, and link to positive disciplinary directions. The authors conclude by encouraging rehabilitation psychologists and other members of the discipline to (re)acquaint themselves with this important book and the timeless concepts it espouses.

Dunn, Dana S.; Elliott, Timothy R.

2008-01-01

166

Faraday effect revisited: sum rules and convergence issues  

NASA Astrophysics Data System (ADS)

This is the third paper of a series revisiting the Faraday effect. The question of the absolute convergence of the sums over the band indices entering the Verdet constant is considered. In general, sum rules and traces per unit volume play an important role in solid-state physics, and they give rise to certain convergence problems widely ignored by physicists. We give a complete answer in the case of smooth potentials and formulate a number of open problems related to less regular perturbations.

Cornean, Horia D.; Nenciu, Gheorghe

2010-11-01

167

Massless Axions: the Callan-Harvey effect revisited  

NASA Astrophysics Data System (ADS)

Axion-like degrees of freedom appear in the low energy physics of various condensed matter systems, which range from quantum spin systems and superconductors to topological insulators and their variants. When topological defects such as domain walls and vortices are formed by the axion fields, their responses to external fields are dominated by the current inflow from the surrounding bulk (Callan-Harvey effect). However, a dual reformulation due to Izquierdo-Townsend is known to present a controversy regarding the existence of this inflow in the case when axions are massless, and can have important consequences. We revisit this problem and discuss its possible relevance to condensed matters.

Kikuchi, Toru; Tanaka, Akihiro

2013-03-01

168

Nonlinear realization of spontaneously broken N = 1 supersymmetry revisited  

NASA Astrophysics Data System (ADS)

This paper revisits the nonlinear realization of spontaneously broken N = 1 supersymmetry. It is shown that the constrained superfield formalism as proposed in [6] can be reinterpreted in the language of standard realization of nonlinear supersymmetry via a new and simpler route. Explicit formulas of actions are presented for general renormalizable theories with or without gauge interactions. The nonlinearWess-Zumino gauge is discussed and relations are pointed out for different definitions of gauge fields. In addition, a general procedure is provided to deal with theories of arbitrary Kahler potentials.

Luo, Hui; Luo, Mingxing; Wang, Liucheng

2010-02-01

169

GENETIC INFLUENCES ON BRAIN ASYMMETRY: A DTI STUDY OF 374 TWINS AND SIBLINGS  

PubMed Central

Brain asymmetry, or the structural and functional specialization of each brain hemisphere, has fascinated neuroscientists for over a century. Even so, genetic and environmental factors that influence brain asymmetry are largely unknown. Diffusion tensor imaging (DTI) now allows asymmetry to be studied at a microscopic scale by examining differences in fiber characteristics across hemispheres rather than differences in structure shapes and volumes. Here we analyzed 4 Tesla DTI scans from 374 healthy adults, including 60 monozygotic twin pairs, 45 same-sex dizygotic pairs, and 164 mixed-sex DZ twins and their siblings; mean age: 24.4 years +/? 1.9SD). All DTI scans were nonlinearly aligned to a geometrically-symmetric, population-based image template. We computed voxel-wise maps of significant asymmetries (left/right differences) for common diffusion measures that reflect fiber integrity (fractional and geodesic anisotropy; FA, GA and mean diffusivity, MD). In quantitative genetic models computed from all same-sex twin pairs (N=210 subjects), genetic factors accounted for 33% of the variance in asymmetry for the inferior fronto-occipital fasciculus, 37% for the anterior thalamic radiation, and 20% for the forceps major and uncinate fasciculus (all L>R). Shared environmental factors accounted for around 15% of the variance in asymmetry for the cortico-spinal tract (R>L) and about 10% for the forceps minor (L>R). Sex differences in asymmetry (men > women) were significant, and were greatest in regions with prominent FA asymmetries. These maps identify heritable DTI-derived features, and may empower genome-wide searches for genetic polymorphisms that influence brain asymmetry.

Jahanshad, Neda; Lee, Agatha D.; Barysheva, Marina; McMahon, Katie L.; de Zubicaray, Greig I.; Martin, Nicholas G.; Wright, Margaret J.; Toga, Arthur W.; Thompson, Paul M.

2011-01-01

170

Genetic influences on brain asymmetry: a DTI study of 374 twins and siblings.  

PubMed

Brain asymmetry, or the structural and functional specialization of each brain hemisphere, has fascinated neuroscientists for over a century. Even so, genetic and environmental factors that influence brain asymmetry are largely unknown. Diffusion tensor imaging (DTI) now allows asymmetry to be studied at a microscopic scale by examining differences in fiber characteristics across hemispheres rather than differences in structure shapes and volumes. Here we analyzed 4Tesla DTI scans from 374 healthy adults, including 60 monozygotic twin pairs, 45 same-sex dizygotic pairs, and 164 mixed-sex DZ twins and their siblings; mean age: 24.4years+/-1.9 SD). All DTI scans were nonlinearly aligned to a geometrically-symmetric, population-based image template. We computed voxel-wise maps of significant asymmetries (left/right differences) for common diffusion measures that reflect fiber integrity (fractional and geodesic anisotropy; FA, GA and mean diffusivity, MD). In quantitative genetic models computed from all same-sex twin pairs (N=210 subjects), genetic factors accounted for 33% of the variance in asymmetry for the inferior fronto-occipital fasciculus, 37% for the anterior thalamic radiation, and 20% for the forceps major and uncinate fasciculus (all L>R). Shared environmental factors accounted for around 15% of the variance in asymmetry for the cortico-spinal tract (R>L) and about 10% for the forceps minor (L>R). Sex differences in asymmetry (men>women) were significant, and were greatest in regions with prominent FA asymmetries. These maps identify heritable DTI-derived features, and may empower genome-wide searches for genetic polymorphisms that influence brain asymmetry. PMID:20430102

Jahanshad, Neda; Lee, Agatha D; Barysheva, Marina; McMahon, Katie L; de Zubicaray, Greig I; Martin, Nicholas G; Wright, Margaret J; Toga, Arthur W; Thompson, Paul M

2010-04-27

171

Relationship of a variant in the NTRK1 gene to white matter microstructure in young adults.  

PubMed

The NTRK1 gene (also known as TRKA) encodes a high-affinity receptor for NGF, a neurotrophin involved in nervous system development and myelination. NTRK1 has been implicated in neurological function via links between the T allele at rs6336 (NTRK1-T) and schizophrenia risk. A variant in the neurotrophin gene, BDNF, was previously associated with white matter integrity in young adults, highlighting the importance of neurotrophins to white matter development. We hypothesized that NTRK1-T would relate to lower fractional anisotropy in healthy adults. We scanned 391 healthy adult human twins and their siblings (mean age: 23.6 ± 2.2 years; 31 NTRK1-T carriers, 360 non-carriers) using 105-gradient diffusion tensor imaging at 4 tesla. We evaluated in brain white matter how NTRK1-T and NTRK1 rs4661063 allele A (rs4661063-A, which is in moderate linkage disequilibrium with rs6336) related to voxelwise fractional anisotropy-a common diffusion tensor imaging measure of white matter microstructure. We used mixed-model regression to control for family relatedness, age, and sex. The sample was split in half to test reproducibility of results. The false discovery rate method corrected for voxelwise multiple comparisons. NTRK1-T and rs4661063-A correlated with lower white matter fractional anisotropy, independent of age and sex (multiple-comparisons corrected: false discovery rate critical p = 0.038 for NTRK1-T and 0.013 for rs4661063-A). In each half-sample, the NTRK1-T effect was replicated in the cingulum, corpus callosum, superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculus, superior corona radiata, and uncinate fasciculus. Our results suggest that NTRK1-T is important for developing white matter microstructure. PMID:22539856

Braskie, Meredith N; Jahanshad, Neda; Stein, Jason L; Barysheva, Marina; Johnson, Kori; McMahon, Katie L; de Zubicaray, Greig I; Martin, Nicholas G; Wright, Margaret J; Ringman, John M; Toga, Arthur W; Thompson, Paul M

2012-04-25

172

Effects of early-life adversity on white matter diffusivity changes in patients at risk for major depression  

PubMed Central

Background Relatives of patients with major depressive disorder (MDD) and people who experienced early-life adversity are at risk for MDD. The aim of our study was to investigate whether unaffected first-degree healthy relatives (UHRs) of patients with MDD show changes in white matter fibre connections compared with healthy controls and whether there are interactions between early-life adversity and these microstructural changes. Methods Unaffected, healthy first-degree relatives of patients with MDD and healthy controls without any family history for a psychiatric disease underwent high angular resolution diffusion imaging with 61 diffusion directions. Data were analyzed with tract-based spatial statistics, and findings were confirmed with tractography. Results Twenty-one UHRs and 24 controls participated in our study. The UHRs showed greater fractional anisotropy than controls in the body and splenium of the corpus callosum, inferior fronto-occipital fasciculus (IFO), left superior longitudinal fasciculus (SLF) and right fornix. The UHRs who experienced more early-life adversity had greater fractional anisotropy than those with less early-life adversity in the splenium of the corpus callosum, fornix, IFO and SLF; in controls, early-life adversity was found to be associated with decreased fractional anisotropy in these fibre tracts. Limitations Studying participants’ strategies for coping with early-life adversity would have been helpful. Crossing fibres in tracts are a general limitation of the method used. Conclusion Altogether, our findings provide evidence for greater fractional anisotropy in UHRs and for interaction between early-life adversity and family risk on white matter tracts involved in cognitive–emotional processes. Whether stronger neural fibre connections are associated with more resilience against depression needs to be addressed in future studies.

Frodl, Thomas; Carballedo, Angela; Fagan, Andrew J.; Lisiecka, Danuta; Ferguson, Yolande; Meaney, James F.

2012-01-01

173

Evidence of frontotemporal structural hypoconnectivity in social anxiety disorder: A quantitative fiber tractography study.  

PubMed

Investigation of the brain's white matter fiber tracts in social anxiety disorder (SAD) may provide insight into the underlying pathophysiology. Because models of pathological anxiety posit altered frontolimbic interactions, the uncinate fasciculus (UF) connecting (orbito-) frontal and temporal areas including the amygdala is of particular interest. Microstructural alterations in parts of the UF have been reported previously, whereas examination of the UF as discrete fiber tract with regard to more large-scale properties is still lacking. Diffusion tensor imaging was applied in 25 patients with generalized SAD and 25 healthy control subjects matched by age and gender. By means of fiber tractography, the UF was reconstructed for each participant. The inferior fronto-occipital fasciculus (IFOF), originating from the frontal cortex similarly to the UF, was additionally included as control tract. Volume and fractional anisotropy (FA) were compared between the groups for both tracts. Volume of left and right UF was reduced in patients with SAD, reaching statistical significance for the left UF. Bilateral IFOF volume was not different between groups. A similar pattern was observed for FA. Reduced volume of the left UF in SAD fits well into pathophysiological models of anxiety, as it suggests deficient structural connectivity between higher-level control areas in the orbitofrontal cortex and more basal limbic areas like the amygdala. The results point to a specific role of the left UF with regard to altered white matter volume in SAD. However, results should be replicated and functional correlates of altered UF volume be determined in future studies. PMID:22076860

Baur, Volker; Brühl, Annette Beatrix; Herwig, Uwe; Eberle, Tanja; Rufer, Michael; Delsignore, Aba; Jäncke, Lutz; Hänggi, Jürgen

2011-11-11

174

White matter microstructure in untreated first episode bipolar disorder with psychosis: comparison with schizophrenia  

PubMed Central

Objectives White matter abnormalities have been reported in bipolar disorder. The present study aimed to investigate white matter integrity in untreated first episode patients with psychotic bipolar disorder using diffusion tensor imaging, and to compare observations with those from untreated first episode schizophrenia patients. Methods Fractional anisotropy and mean diffusivity were measured in first episode psychotic patients with bipolar disorder (n = 13) or schizophrenia (n = 21) and healthy individuals (n = 18). Group differences were evaluated using voxel based morphometry. Axial and radial diffusivity were examined in regions with altered fractional anisotropy in post-hoc analyses. Results Patients with bipolar disorder showed lower fractional anisotropy than healthy controls in several white matter tracts. Compared with schizophrenia patients, bipolar disorder patients showed lower fractional anisotropy in the cingulum, internal capsule, posterior corpus callosum, tapetum, and occipital white matter including posterior thalamic radiation and inferior longitudinal fasciculus/inferior fronto-occipital fasciculus. Lower fractional anisotropy in bipolar disorder was characterized by increased radial diffusion rather than axial diffusion along the orientation of fiber tracts. Across several white matter tracts, both patient groups showed greater mean diffusivity than healthy individuals. Conclusions Selectively increased radial diffusivity in bipolar disorder patients suggests structural disorganization in fiber tract coherence of neurodevelopmental origin or alterations in myelin sheaths along fiber tracts. In contrast, increased isotropic diffusion along white matter tracts in schizophrenia patients with alterations in both radial and axial diffusivity suggests increased water content outside of axonal space. Thus, the present results suggest that different pathophysiological mechanisms may underlie white matter microstructural abnormalities in bipolar disorder and schizophrenia.

Lu, Lisa H; Zhou, Xiaohong Joe; Keedy, Sarah K; Reilly, James L; Sweeney, John A

2012-01-01

175

White matter integrity, substance use, and risk taking in adolescence.  

PubMed

White matter development is important for efficient communication between brain regions, higher order cognitive functioning, and complex behaviors. Adolescents have a higher propensity for engaging in risky behaviors, yet few studies have explored associations between white matter integrity and risk taking directly. Altered white matter integrity in mid-adolescence was hypothesized to predict subsequent risk taking behaviors 1.5 years later. Adolescent substance users (predominantly alcohol and marijuana, n = 47) and demographically similar nonusers (n = 49) received diffusion tensor imaging at baseline (ages 16-19), and risk taking measures at both baseline and an 18-month follow-up (i.e., at ages 17-20). Brain regions of interest were the fornix, superior corona radiata, superior longitudinal fasciculus, and superior fronto-occipital fasciculus. In substance-using youth (n = 47), lower white matter integrity at baseline in the fornix and superior corona radiata predicted follow-up substance use (?R2 = 10-12%, ps < .01), and baseline fornix integrity predicted follow-up delinquent behaviors (?R2 = 10%, p < .01) 1.5 years later. Poorer fronto-limbic white matter integrity was linked to a greater propensity for future risk taking behaviors among youth who initiated heavy substance use by mid-adolescence. Most notable were relationships between projection and limbic-system fibers and future substance-use frequency. Subcortical white matter coherence, along with an imbalance between the maturation levels in cognitive control and reward systems, may disadvantage the resistance to engage in risk taking behaviors during adolescence. PMID:22564204

Jacobus, Joanna; Thayer, Rachel E; Trim, Ryan S; Bava, Sunita; Frank, Lawrence R; Tapert, Susan F

2012-05-07

176

How important is plot relocation accuracy when interpreting re-visitation studies of vegetation change?  

Microsoft Academic Search

Background: Re-visitation studies are often based on phytosociological survey data where the precise location of the original plots is unknown. Attempts to evaluate the error associated with relocation uncertainty are rare, yet this is important in interpreting the results with any degree of confidence.Aims: Using a 50-year re-visitation study of upland vegetation in the Scottish Highlands, we aim to assess

Louise C. Ross; Sarah J. Woodin; Alison Hester; Des B. A. Thompson; H. John B. Birks

2010-01-01

177

Characterizing cloud cover and satellite revisit with cloud masks in North West England  

Microsoft Academic Search

The aim of this study is to determine the availability of cloud-free images in relation to satellite revisit periods for the UK and in particular for the North West of England. Cloud cover was analysed with cloud masks from AVHRR\\/APOLLO and TERRA\\/MODIS cloud products. Availability of cloud-free images was determined from revisit frequency and the numbers of monthly images from

Ebenezer Yemi Ogunbadewa

2012-01-01

178

Evidence based practice: decreasing psychiatric revisits to the emergency department.  

PubMed

Inpatient psychiatric settings anticipate changes in reimbursement that will link payment rates to objective quality measures. Readmission rates are expected to be one of the quality measures. Inpatient areas are undertaking initiatives to decrease readmission rates in preparation for this change. The emphasis on avoiding readmission could cause an increase in emergency room revisit rates by psychiatric patients. In preparation for this potential impact, the mental health emergency service within the Emergency Department of a not-for-profit community based hospital implemented a proactive process improvement plan. The plan's goal was to insure that all patients' care was provided according to a defined standardize best practice process. Steps of the plan focused on (1) improving treatment providers' communications across the continuum of care, (2) enhancing communication between the mental health emergency department nurses and the on-call psychiatrists, (3) developing on-line decisional support to enhance communication, and (4) providing providers with feedback on the impact of changes. Implementation of the improvement process decreased the mean psychiatric emergency revisit rate from 5.7% to 4.3% and decreased the variability in monthly rates from a range of 1.83%-9.53% to a range of 3.53%-5.56%. PMID:22849781

Adams, Priscilla; Nielson, Heather

2012-08-01

179

Hund's coupling and spin-orbit coupling in iridates revisited  

NASA Astrophysics Data System (ADS)

In recent years iridates have attracted a lot of interests because of unusual properties due to a combination of strong correlations and strong spin-orbit scattering. The magnetic properties of these materials are often analyzed theoretically by applying the Kugel-Khomskii model and specifically considering the J=12 subspace decoupled by strong spin-orbit coupling. It is not obvious that such an approach is always valid, however, given that the spin-orbit coupling, on-site correlation energies, intra-atom exchange energies, tetragonal splittings, etc. all have comparable strength. In this work we will revisit the magnetic interactions of these materials combining insights from an examination of the 2-electron multiplet structure of a t2g ion using the Slater theory of atomic structure, and ab initio electronic structure calculations. We will also discuss the the magnetic anisotropy and domain-wall energies of specific iridate materials implied by these magnetic interactions.

Chen, Hua; Khalsa, Guru; MacDonald, Allan H.

2013-03-01

180

Revisiting the Response Mechanism of Polymeric Membrane Based Heparin Electrodes  

PubMed Central

Potentiometric membrane electrodes that respond to heparin and other polyanions were introduced in the early 1990s. Herein, the mechanism of polymer membrane electrode type heparin sensors is revisited. The extraction/diffusion of heparin is studied via both potentiometric and impedance spectroscopic techniques using a pre-fractionated heparin preparation that contains polyanionic species > 10000 Daltons. The reversal in EMF response using this heparin preparation indicates diffusion of higher MW heparin fragments to the backside of the membrane. Diffusion coefficients are calculated using a novel formula derived from the phase boundary potential model and Fick's second law of diffusion. Impedance spectroscopy is also employed to show that high MW heparin species are extracted and diffuse across the PVC membranes.

Bell, Andrea K.; Hofler, Lajos; Meyerhoff, Mark E.

2012-01-01

181

Bond energy analysis revisited and designed toward a rigorous methodology  

NASA Astrophysics Data System (ADS)

The present study theoretically revisits and numerically assesses two-body energy decomposition schemes including a newly proposed one. The new decomposition scheme is designed to make the equilibrium bond distance equivalent with the minimum point of bond energies. Although the other decomposition schemes generally predict the wrong order of the C-C bond strengths of C2H2, C2H4, and C2H6, the new decomposition scheme is capable of reproducing the C-C bond strengths. Numerical assessment on a training set of molecules demonstrates that the present scheme exhibits a stronger correlation with bond dissociation energies than the other decomposition schemes do, which suggests that the new decomposition scheme is a reliable and powerful analysis methodology.

Nakai, Hiromi; Ohashi, Hideaki; Imamura, Yutaka; Kikuchi, Yasuaki

2011-09-01

182

Online haemodiafiltration: definition, dose quantification and safety revisited.  

PubMed

The general objective assigned to the EUropean DIALlysis (EUDIAL) Working Group by the European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) was to enhance the quality of dialysis therapies in Europe in the broadest possible sense. Given the increasing interest in convective therapies, the Working Group has started by focusing on haemodiafiltration (HDF) therapies. Several reports suggest that those therapies potentially improve the outcomes for end-stage renal disease patients. Europe is the leader in the field, having introduced the concept of ultra-purity for water and dialysis fluids and with notified bodies of the European Community having certified water treatment systems and online HDF machines. The prevalence of online HDF-treated patients is steadily increasing in Europe, averaging 15%. A EUDIAL consensus conference was held in Paris on 13 October 2011 to revisit terminology, safety and efficacy of online HDF. This is the first report of the expert group arising from that conference. PMID:23345621

Tattersall, James E; Ward, Richard A

2013-01-22

183

Revisiting total, matric, and osmotic suction in partially saturated geomaterials  

NASA Astrophysics Data System (ADS)

An accurate quantification of negative pore pressure (commonly referred to as `suction') in the pore network is necessary for modeling the mechanical response of unsaturated geomaterials. Traditional definitions and formulations of total, matric, and osmotic suction suggest incorrect pore fluid pressures under certain conditions. In this paper, the notion of suction is revisited by deriving an expression for pore fluid pressure in a simple osmotic, capillary tube using the framework of mixture theory in conjunction with the fundamental laws of thermodynamics. Based on the derived expression for the tube, expressions are derived for total, matric, and osmotic suction for partially saturated geomaterials. Particular attention is given to osmotic suction since confusion regarding its mechanisms has apparently contributed to its misapplication in geomechanics. The new expressions derived herein adequately explain behavior that is incorrectly explained by the traditional formulations and unifies two approaches to modeling osmotic suction previously considered to be in contradiction.

Grasley, Zachary C.; Rajagopal, Kumbakonam R.

2012-04-01

184

Energy in synthetic fertilizers and pesticides: Revisited. Final project report  

SciTech Connect

Agricultural chemicals that are derived from fossil-fuels are the major energy intensive inputs in agriculture. Growing scarcity of the world`s fossil resources stimulated research and development of energy-efficient technology for manufacturing these chemicals in the last decade. The purpose of this study is to revisit the energy requirements of major plant nutrients and pesticides. The data from manufacturers energy survey conducted by The Fertilizer Institute are used to estimate energy requirements of fertilizers. Energy estimates for pesticides are developed from consulting previously published literature. The impact of technical innovation in the fertilizer industry to US corn, cotton, soybean and wheat producers is estimated in terms of energy-saving.

Bhat, M.G.; English, B.C.; Turhollow, A.F.; Nyangito, H.O. [Tennessee Univ., Knoxville, TN (United States). Dept. of Agricultural Economics and Rural Sociology

1994-01-01

185

Seismic demand of plan-asymmetric structures: a revisit  

NASA Astrophysics Data System (ADS)

In view of the recognition of the importance of the interdependent behavior of strength and stiffness of walltype structural elements, the seismic demand of plan-asymmetric systems is revisited. Useful strength distribution strategies, i.e., `Center of Strength-Center of Mass (CV-CM) coinciding' and `Balanced Center of Strength-Center of Resistance (CVCR)' are adopted. Design charts for the seismic demand of classical uni-directionally and bi-directionally asymmetric systems are developed in a simple unified format. A conceptual framework is also outlined to conveniently apply the design charts. Illustrations are included to explain the use of the current recommendations in practical design. The study also highlights the relative performance of `CV-CM coinciding' and `Balanced CV-CR' criteria.

Roy, Rana; Chakroborty, Suvonkar

2013-03-01

186

Response Variance in Functional Maps: Neural Darwinism Revisited  

PubMed Central

The mechanisms by which functional maps and map plasticity contribute to cortical computation remain controversial. Recent studies have revisited the theory of neural Darwinism to interpret the learning-induced map plasticity and neuronal heterogeneity observed in the cortex. Here, we hypothesize that the Darwinian principle provides a substrate to explain the relationship between neuron heterogeneity and cortical functional maps. We demonstrate in the rat auditory cortex that the degree of response variance is closely correlated with the size of its representational area. Further, we show that the response variance within a given population is altered through training. These results suggest that larger representational areas may help to accommodate heterogeneous populations of neurons. Thus, functional maps and map plasticity are likely to play essential roles in Darwinian computation, serving as effective, but not absolutely necessary, structures to generate diverse response properties within a neural population.

Takahashi, Hirokazu; Yokota, Ryo; Kanzaki, Ryohei

2013-01-01

187

Revisiting Public Health Challenges in the New Millennium  

PubMed Central

Positive Health of the communities could only be brought out through the interrelationship between conventional health sector and other development sectors. It was a dream that came true when World Health Organization (WHO) accepted Primary Health Care (PHC) as the major tool to achieve its proposed goal of Health For All (HFA) by 2000 A.D., but we could not succeed as expected. Now we have the Millennium Development Goals (MDG), which place health at the heart of development but the achievements in health is still challenging. The literature search in this article has been conducted in Pub Med and Google scholar, with the aim to draw references to discuss the major health issues and ways to tackle them. The current article briefly narrates the burden and complexities of challenges faced by the present global health. Revisiting the concept of PHC and reaffirming our solidarity to this philosophy is the need of this hour.

Anish, TS; Sreelakshmi, PR

2013-01-01

188

Small-angle Scattering Theory Revisited: Photocurrent and Spatial Localization  

NASA Astrophysics Data System (ADS)

In this paper theory on collective scattering measurements of electron density fluctuations in fusion plasmas is revisited. We present the first full derivation of the expression for the photocurrent beginning at the basic scattering concepts. Thereafter we derive detailed expressions for the auto- and crosspower spectra obtained from measurements. These are discussed and simple simulations made to elucidate the physical meaning of the findings. In this context, the known methods of obtaining spatial localization are discussed and appraised. Where actual numbers are applied, we utilize quantities from two collective scattering instruments The ALTAIR diagnostic on the Tore Supra tokamak [A Truc et al, "ALTAIR An infrared laser scattering diagnostic on the Tore Supra tokamak", Rev. Sci. Instrum. 63 3716 3724 (1992)] and the LOTUS diagnostic on the Wendelstein 7-AS stellarator [M Saffman et al, "CO2 laser based two-volume collective scattering instrument for spatially localized turbulence measurements", Rev. Sci. Instrum. 72 2579 2592 (2001)].

Basse, N. P.; Zoletnik, S.; Michelsen, P. K.

2005-01-01

189

Pseudoscalar N-flation and axial coupling revisited  

NASA Astrophysics Data System (ADS)

We revisit the dynamics of the axial coupling between many N-flatons and an Abelian gauge field, with special attention to its statistically anisotropic signal. The anisotropic power spectrum of curvature perturbations associated with the large-wavelength modes of the gauge vector field is generally undetectable, since the anisotropy is confined to small scales. If the gauge field is the electromagnetic field, provided that the number of fields participating in the exponential expansion is large, it could be possible to generate sizable large-scale magnetic fields. However, its spectrum is blue, and appreciable power on large scales implies an overly strong field on smaller scales, incompatible with observations. Furthermore, the anisotropy is also markedly enhanced, and might be at odds with the isotropic observed sky. These aspects further demand that the scale of inflation be kept to a minimum.

Urban, Federico R.

2013-09-01

190

Revisiting the 100 Year Old Radioactivity Lectures of Frederick Soddy  

NASA Astrophysics Data System (ADS)

Between 1908 and 1922, Frederick Soddy, MA., FRS (Dr. Lee`s Professor of Inorganic and Physical Chemistry, Univ. of Oxford) published four editions of a compendium of his experimental lectures delivered at the University of Glasgow, under the title ``The Interpretation of Radium, and the Structure of the Atom''. Professor Soddy taught his students about `radium writing' and the emanation of radium. He presented a radium clock designed by Professor Strutt; showed students `Pleochroic Halos'; and described the separation of `ionium' from its isotope, thorium. The process of constructing a cohesive logic to empirical observations of this newly discovered phenomenon of radioactivity was a challenging one. Some aspects did not stand the test of time. However, revisiting these lectures after 100 years gives us fascinating insight into the mental processes of the early pioneers in radioactivity.

Hampton, Christine

2008-04-01

191

Word learning is mediated by the left arcuate fasciculus.  

PubMed

Human language requires constant learning of new words, leading to the acquisition of an average vocabulary of more than 30,000 words in adult life. The ability to learn new words is highly variable and may rely on the integration between auditory and motor information. Here, we combined diffusion imaging tractography and functional MRI to study whether the strength of anatomical and functional connectivity between auditory and motor language networks is associated with word learning ability. Our results showed that performance in word learning correlates with microstructural properties and strength of functional connectivity of the direct connections between Broca's and Wernicke's territories in the left hemisphere. This study suggests that our ability to learn new words relies on an efficient and fast communication between temporal and frontal areas. The absence of these connections in other animals may explain the unique ability of learning words in humans. PMID:23884655

López-Barroso, Diana; Catani, Marco; Ripollés, Pablo; Dell'Acqua, Flavio; Rodríguez-Fornells, Antoni; de Diego-Balaguer, Ruth

2013-07-24

192

Reading Impairment in a Patient with Missing Arcuate Fasciculus  

ERIC Educational Resources Information Center

|We describe the case of a child ("S") who was treated with radiation therapy at age 5 for a recurrent malignant brain tumor. Radiation successfully abolished the tumor but caused radiation-induced tissue necrosis, primarily affecting cerebral white matter. "S" was introduced to us at age 15 because of her profound dyslexia. We assessed cognitive…

Rauschecker, Andreas M.; Deutsch, Gayle K.; Ben-Shachar, Michal; Schwartzman, Armin; Perry, Lee M.; Dougherty, Robert F.

2009-01-01

193

Revisit of WHP P17N in 2001  

NASA Astrophysics Data System (ADS)

During the WHP P17N revisit cruise by R/V Mirai in 2001 summer, we carried out hydrographic observations in the eastern North Pacific from 30 to 55 N degrees. A total of 78 CTDO/rosette stations were conducted and more than 3,500 seawater samples for salinity, oxygen, phosphate, silicate, nitrate, nitrite, dissolved inorganic carbon (DIC), pH, and alkalinity were measured on board. Additionally, vertical profiles of radiocarbon and carbon-13 of DIC were also measured at 21 stations (about 700 samples). Comparison of hydrographic data between the first visit in the early 1990s (P17N in 1993 and P17C in 1991) and the re-visit elucidated temporal changes of intermediate water properties in the eastern North Pacific in the 1990s. From the subtropical region to the Alaskan Gyre, apparent oxygen utilization (AOU) in intermediate layers (26 - 27 sigma-theta) increased by up to 60 micro-mol/kg with increased nutrients and DIC concentrations. Patchy AOU increases in the subtropical region (30 - 40 N degrees) suggest that high AOU water was brought by mesoscale eddies from the east, off of California, where oxygen concentration is low. Between 41 and 53 N degrees, a tongue of AOU increase was measured around 26.6 sigma-theta isopycnal. This AOU increase is in agreement with previous studies showing AOU and CFC age increases along 152 W degrees from 30 to 45 N degrees between 1991 and 1997 (Emerson et al., 2001) and along 47 N degrees from 160 E to 145 W degrees between 1985 and 1999 (Watanabe et al., 2001). Furthermore, the AOU increase was larger in the Alaskan Gyre from 44 to 53 N degrees and was associated with intensification of stratification. These results suggest that ventilation rate of intermediate water slowed down in the subpolar and the subpolar/subtropical transition regions of the eastern North Pacific during the 1990s. Measured changes of the carbon-13 and radiocarbon of DIC also imply stagnation of the subpolar intermediate water.

Kumamoto, Y.; Murata, A.; Watanabe, S.; Fukasawa, M.; Uchida, H.; Quay, P.; Yoneda, M.; Shibata, Y.; Morita, M.

2004-12-01

194

A Revisit of the Theoretical Model of Store Image and Its Application to Chinese Consumers  

Microsoft Academic Search

This study revisits the theoretical model of store image and examines its application to both American and Chinese samples. The researchers used structural equation modeling techniques to analyze the data. Their findings indicated that in both countries consumer evaluation of store attributes or their cognitive response has a direct effect on shopping intention, as do consumers' feelings or their affective

Haiyan Hu; Cynthia R. Jasper

2010-01-01

195

Revisiting the concept of components in software engineering from a software ecosystem perspective  

Microsoft Academic Search

The treatment of economic and social issues in Software Engineering (SE) was pointed out as a challenge for the next years, since SE needs to treat issues beyond the technical side, which requires observing it in another perspective. In this sense, this paper revisits the concept of components in SE through a sociotechnical construction. Based on a ranking of its

Rodrigo Pereira dos Santos; Cláudia Maria Lima Werner

2010-01-01

196

Resampling methods revisited: advancing the understanding and applications in educational research  

Microsoft Academic Search

Resampling methods including randomization test, cross?validation, the jackknife and the bootstrap are widely employed in the research areas of natural science, engineering and medicine, but they lack appreciation in educational research. The purpose of the present review is to revisit and highlight the key principles and developments of resampling methods to advance the understanding and applications of resampling methods in

Haiyan Bai; Wei Pan

2008-01-01

197

Revisiting First-Year College Students' Mattering: Social Support, Academic Stress, and the Mattering Experience  

ERIC Educational Resources Information Center

In this study, Nancy Schlossberg's (1989) theory of college students' mattering to others was revisited. Mattering is the experience of others depending on us, being interested in us, and being concerned with our fate. The relationships of gender, mattering to college friends and the college environment, and friend and family social support with…

Rayle, Andrea Dixon; Chung, Kuo-Yi

2008-01-01

198

DNA as Genetic Material: Revisiting Classic Experiments through a Simple, Practical Class  

ERIC Educational Resources Information Center

|In 1928, Frederick Griffith demonstrated a transmission process of genetic information by transforming "Pneumococcus". In 1944, Avery et al. demonstrated that Griffith's transforming principle was DNA. We revisited these classic experiments in a practical class for undergraduate students. Both experiments were reproduced in simple, adapted forms.…

Malago, Wilson, Jr.; Soares-Costa, Andrea; Henrique-Silva, Flavio

2009-01-01

199

Revisiting the Civic Duty to Keep Informed in the New Media Environment  

Microsoft Academic Search

The present study revisits the relationship between the civic duty to keep informed and news media use in the new media environment, then discovers that the civic duty to keep informed functions as an intervening variable between education and news media use. Of particular theoretical interest is that the civic duty to keep informed was found to be a consequence

Paula M. Poindexter; Maxwell E. McCombs

2001-01-01

200

Globalisation, the Singapore Developmental State and Education Policy: A Thesis Revisited  

ERIC Educational Resources Information Center

In this article I revisit and extend arguments made in 1996 and 1997 about the relationship between globalisation, the state and education policy. I was particularly concerned then to see how a small but strong state, Singapore, was responding in the education arena to globalisation. I also wished to draw attention to the literature on the high…

Gopinathan, S.

2007-01-01

201

Considerations of the Social, Individual, and Embodied: A Response to Comments on "Schema Theory Revisited"  

ERIC Educational Resources Information Center

|This article presents the authors' response and clarifications to the comments of Margaret E. Gredler and of Karen A. Krasny, Mark Sadoski, and Allan Paivio on their article "Schema Theory Revisited." The authors first respond to Gredler's criticism contending that they "transmogrified" Harre's (1984) "ignominiously named...Vygotsky space" in…

McVee, Mary B.; Gavelek, James R.; Dunsmore, Kailonnie L.

2007-01-01

202

Ambiguity Advantage Revisited: Two Meanings Are Better than One when Accessing Chinese Nouns  

ERIC Educational Resources Information Center

|This paper revisits the effect of lexical ambiguity in word recognition, which has been controversial as previous research reported advantage, disadvantage, and null effects. We discuss factors that were not consistently treated in previous research (e.g., the level of lexical ambiguity investigated, parts of speech of the experimental stimuli,…

Lin, Chien-Jer Charles; Ahrens, Kathleen

2010-01-01

203

Revisiting the relation between environmental performance and environmental disclosure: An empirical analysis  

Microsoft Academic Search

Previous empirical evidence provides mixed results on the relationship between corporate environmental perfor- mance and the level of environmental disclosures. We revisit this relation by testing competing predictions from eco- nomics based and socio-political theories of voluntary disclosure using a more rigorous research design. In particular, we improve on the prior literature by focusing on purely discretionary environmental disclosures and

Peter M. Clarkson; Yue Li; Gordon D. Richardson; Florin P. Vasvari

2007-01-01

204

The Gottfredson-Hirschi Critiques Revisited: Reconciling Self-Control Theory, Criminal Careers, and Career Criminals  

Microsoft Academic Search

Revisiting Gottfredson and Hirschi's critiques of criminal career research, the current study views low self-control as being analogous to criminal propensity and examines its predictive validity of career criminality among 723 incarcerated delinquent youths. Four key findings emerged. Compared to noncareer offenders, career criminals had significantly lower levels of self-control. Second, youths scoring one standard deviation above the mean on

Matt DeLisi; M. G. Vaughn

2007-01-01

205

EPR before EPR: A 1930 Einstein-Bohr thought Experiment Revisited  

ERIC Educational Resources Information Center

|In 1930, Einstein argued against the consistency of the time-energy uncertainty relation by discussing a thought experiment involving a measurement of the mass of the box which emitted a photon. Bohr seemingly prevailed over Einstein by arguing that Einstein's own general theory of relativity saves the consistency of quantum mechanics. We revisit

Nikolic, Hrvoje

2012-01-01

206

Increasing the Degrees of Freedom in Future Group Randomized Trials: The "df*" Method Revisited  

ERIC Educational Resources Information Center

|Background: This article revisits an article published in Evaluation Review in 2005 on sample size estimation and power analysis for group-randomized trials. With help from a careful reader, we learned of an important error in the spreadsheet used to perform the calculations and generate the results presented in that article. As we studied the…

Murray, David M.; Blitstein, Jonathan L.; Hannan, Peter J.; Shadish, William R.

2012-01-01

207

Revisiting Marshall's Agglomeration Economies: Technological Relatedness and the Evolution of the Sheffield Metals Cluster  

Microsoft Academic Search

Potter A. and Watts H. D. Revisiting Marshall's agglomeration economies: technological relatedness and the evolution of the Sheffield metals cluster, Regional Studies. According to Alfred Marshall, firms receive increasing returns from a trinity of agglomeration economies: a local pool of skilled labour, local supplier linkages and local knowledge spillovers. This article re-examines the mechanisms underlying Marshall's agglomeration economies in the

Antony Potter; H. Doug Watts

2012-01-01

208

The Concept of Experience by John Dewey Revisited: Conceiving, Feeling and "Enliving"  

ERIC Educational Resources Information Center

|"The concept of experience by John Dewey revisited: conceiving, feeling and 'enliving'." Dewey takes a few steps towards a differentiation of the concept of experience, such as the distinction between primary and secondary experience, or between ordinary (partial, raw, primitive) experience and complete, aesthetic experience. However, he does not…

Hohr, Hansjorg

2013-01-01

209

Convergence of Relative State-level Per Capita Incomes in the United States Revisited  

Microsoft Academic Search

In this paper convergence in per capita incomes (personal and disposable) in US states over 1929-2005 is revisited using the notion of relative stochastic convergence and stationarity tests for panel data. According to the results, although the dispersion of per capita income be- came stationary by the early 1960s a large proportion of states have not converged to the na-

Panos Fousekis

2007-01-01

210

Gamma-ray Burst Prompt Emission: Jitter Radiation in Stochastic Magnetic Field Revisited  

Microsoft Academic Search

We revisit the radiation mechanism of relativistic electrons in the stochastic magnetic field and apply it to the high-energy emissions of gamma-ray bursts (GRBs). We confirm that jitter radiation is a possible explanation for GRB prompt emission in the condition of a large electron deflection angle. In the turbulent scenario, the radiative spectral property of GRB prompt emission is decided

Jirong Mao; Jiancheng Wang

2011-01-01

211

Revisiting coupled Shukla-Varma and convective cell mode in classical and quantum dusty magnetoplasmas  

NASA Astrophysics Data System (ADS)

The coupled Shukla-Varma (SV) and convective cell mode is revisited in classical and quantum dusty magnetoplasmas. It is shown that the inclusion of electron thermal effects modifies the original coupled SV and convective cell mode. It is also discussed how the quantum effects can be incorporated in the coupled SV and convective cell mode.

Masood, W.; Mirza, A. M.; Nargis, S.

2010-08-01

212

The Neutrosophic Logic View to Schr"odinger Cat Paradox, Revisited  

NASA Astrophysics Data System (ADS)

The present article discusses Neutrosophic logic view to Schr"odinger's cat paradox. We argue that this paradox involves some degree of indeterminacy (unknown) which Neutrosophic logic can take into consideration. To make this proposition clear, we revisit a previous paper of ours by offering an illustration using modified coin tossing problem, known as Parrondo's game.

Smarandache, Florentin; Christianto, Vic

2010-03-01

213

Flashpoints Revisited: A Critical Application to the Policing of Anti-globalization Protest  

Microsoft Academic Search

The Flashpoints model, developed by David Waddington and colleagues in the late 1980s, has been utilized to examine various public order occurrences, ranging from urban rioting, industrial unrest and animal rights protests of the 1990s, primarily focusing on the United Kingdom, with some examples from the United States of America. This article revisits and reappraises the model in the light

Mike King; David Waddington

2005-01-01

214

Critical Language Awareness in the United States: Revisiting Issues and Revising Pedagogies in a Resegregated Society  

ERIC Educational Resources Information Center

|As scholars examine the successes and failures of more than 50 years of court-ordered desegregation since "Brown v. Board of Education of Topeka, Kansas," and 25 years of language education of Black youth since "Martin Luther King Elementary School Children v. Ann Arbor School District Board," this article revisits the key issues involved in…

Alim, H. Samy

2005-01-01

215

Short article Revisiting places passed: Sensitization of exploratory activity in rats with hippocampal lesions  

Microsoft Academic Search

We examined the involvement of the hippocampus in short-term changes in exploratory behaviour in an open field (Experiment 1) and experimental contexts (Experiment 2). In Experiment 1, rats with excitotoxic lesions of the hippocampus were more likely to revisit recently visited zones within the open field than were control rats. Similarly, in Experiment 2 rats with hippocampal lesions showed greater

R. C. Honey; V. J. Marshall; A. McGregor; J. Futter; M. Good

216

THE MEAN SQUARE ERROR OF PREDICTION IN THE CHAIN LADDER RESERVING METHOD (MACK AND MURPHY REVISITED)  

Microsoft Academic Search

We revisit the famous Mack formula (2), which gives an estimate for the mean square error of prediction MSEP of the chain ladder claims reserving method: We define a time series model for the chain ladder method. In this time series framework we give an approach for the estimation of the conditional MSEP. It turns out that our approach leads

MARKUS BUCHWALDER; H ANS BÜHLMANN; M ICHAEL MERZ; MARIO V. W ÜTHRICH

2006-01-01

217

Re-Visit to the School Nurse and Adolescents' Medicine Use  

ERIC Educational Resources Information Center

|Objective: To examine if students who re-visit the school nurse use medicines differently than other students when exposed to aches and psychological problems. Methods: The study includes all 11-, 13- and 15-year-old students from a random sample of schools in Denmark, response rate 87 per cent, n = 5,205. The data collection followed the…

Borup, Ina K.; Andersen, Anette; Holstein, Bjorn E.

2011-01-01

218

Revisiting the total ion yield x-ray absorption spectra of liquid water microjets  

Microsoft Academic Search

Measurements of the total ion yield (TIY) x-ray absorption spectrum (XAS) of liquid water by Wilson et al (2002 J. Phys.: Condens. Matter14 L221 and 2001 J. Phys. Chem. B 105 3346) have been revisited in light of new experimental and theoretical efforts by our group. Previously, the TIY spectrum was interpreted as a distinct measure of the electronic structure

Christopher D Cappa; Jared D Smith; Kevin R Wilson; Richard J Saykally

2008-01-01

219

Distance Learning Revisited: Life-Long Learning and the National Information Infrastructure.  

ERIC Educational Resources Information Center

|This paper "revisits" distance learning by addressing its past achievements, its present state, and its future in the face of the rapidly converging computer and communications technologies and the goals and potential that underlie the creation of the proposed National Information Infrastructure (NII). The analysis was undertaken recognizing that…

Weisburg, Michael; Ullmer, Eldon J.

220

The Myth of Meeting Needs Revisited: The Case of Educational Research  

ERIC Educational Resources Information Center

|Our primary objective in this paper is revisit a debate that was articulated 25 years ago in this journal in which it was argued that the idea of meeting needs in adult and continuing education is a myth. We extend the original analysis of need and apply it to the case of educational research. We look at the policy context, which has, in the…

Lawy, Robert; Armstrong, Paul

2009-01-01

221

Resampling Methods Revisited: Advancing the Understanding and Applications in Educational Research  

ERIC Educational Resources Information Center

Resampling methods including randomization test, cross-validation, the jackknife and the bootstrap are widely employed in the research areas of natural science, engineering and medicine, but they lack appreciation in educational research. The purpose of the present review is to revisit and highlight the key principles and developments of…

Bai, Haiyan; Pan, Wei

2008-01-01

222

Reading Revisited: Evaluating the Usability of Digital Display Surfaces for Active Reading Tasks  

Microsoft Academic Search

A number of studies have shown that paper holds several advantages over computers for reading tasks. However, these studies were carried out several years ago, and since that time computerized reading technology has advanced in many areas. We revisit the issue of reading in the workplace, comparing paper use to state-of-the-art hardware and software. In particular, we studied how knowledge

Meredith Ringel Morris; A. J. Bernheim Brush; Brian R. Meyers

2007-01-01

223

Reading Revisited: Evaluating the Usability of Digital Display Surfaces for Active Reading Tasks  

Microsoft Academic Search

A number of studies have shown that paper holds several advantages over computers for reading tasks. However, these studies were carried out several years ago, and since that time computerized reading tech- nology has advanced in many areas. We revisit the issue of reading in the workplace, comparing paper use to state-of-the-art hardware and software. In par- ticular, we studied

Meredith Ringel Morris; A. J. Bernheim Brush; Brian R. Meyers

2007-01-01

224

Transformation of Learning in Education and Training: Key Qualifications Revisited. CEDEFOP Reference Series.  

ERIC Educational Resources Information Center

|This book contains 15 papers examining European approaches to the theme of key qualifications. The following papers are included: "Key Qualifications Revisited: An Introduction" (Pekka Kamarainen); "Exploring Key Qualifications: Context, Theory, and Practice in Europe" (Pekka Kamarainen); "Rethinking Key Qualifications: Towards a New Framework"…

Kamarainen, Pekka, Ed.; Attwell, Graham, Ed.; Brown, Alan, Ed.

225

The dynamics of a bouncing ball with a sinusoidally vibrating table revisited  

Microsoft Academic Search

The dynamical behavior of a bouncing ball with a sinusoidally vibrating table is revisited in this paper. Based on the equation of motion of the ball, the mapping for period-1 motion is constructured and thereby allowing the stability and bifurcation conditions to be determined. Comparison with Holmes's solution [1] shows that our range of stable motion is wider, and through

Albert C. J. Luo; Ray P. S. Han

1996-01-01

226

Beliefs, attitude and behaviour towards fresh meat revisited after the Belgian dioxin crisis  

Microsoft Academic Search

This study revisits consumer beliefs, attitude and behaviour towards fresh meat consumption in Belgium after the occurrence of the dioxin crisis of 1999. The meat dioxin scare evoked a large amount of negative press, mainly pertained to poultry meat and pork. The focus of this follow-up study is on assessing shifts and persistence in consumer perception and attitude, based on

Wim Verbeke

2001-01-01

227

Revisiting the Accuracy Hypothesis in Families of Young Children With Conduct Problems  

Microsoft Academic Search

Revisited the accuracy hypothesis in an examination of the relation between maternal depressive symptomatology and child conduct problems. All data were gathered as part of the pretreatment assessment in an outcome study of families with clinic-re - ferred children with conduct problems (age 3 to 6). The mothers varied in their depres - sive symptomatology, from not at all symptomatic

Jane G. Querido; Sheila M. Eyberg; Stephen R. Boggs

2001-01-01

228

Revisiting the Quantitative-Qualitative Debate: Implications for Mixed-Methods Research  

Microsoft Academic Search

Health care research includes many studies that combine quantitative and qualitative methods. In this paper, we revisit the quantitative-qualitative debate and review the arguments for and against using mixed-methods. In addition, we discuss the implications stemming from our view, that the paradigms upon which the methods are based have a different view of reality and therefore a different view of

JOANNA E. M. SALE; LYNNE H. LOHFELD; Kevin Brazil

2002-01-01

229

Increasing the Degrees of Freedom in Future Group Randomized Trials: The "df*" Method Revisited  

ERIC Educational Resources Information Center

Background: This article revisits an article published in Evaluation Review in 2005 on sample size estimation and power analysis for group-randomized trials. With help from a careful reader, we learned of an important error in the spreadsheet used to perform the calculations and generate the results presented in that article. As we studied the…

Murray, David M.; Blitstein, Jonathan L.; Hannan, Peter J.; Shadish, William R.

2012-01-01

230

Sunday School Revisited: An Alternative to Christian Education of the Church Today?  

ERIC Educational Resources Information Center

|This article attempts to demonstrate similarities between the socioeconomic, cultural, and religious contexts of 18th-century England and 21st-century Canada. Revisiting the Sunday School movement in 18th-century England provides insights for the development of renewed Sunday School models in the current Canadian context of transnational…

Song, Nam Soon

2013-01-01

231

Recreancy Revisited: Beliefs about Institutional Failure Following the Exxon Valdez Oil Spill  

Microsoft Academic Search

In 1993, Freudenburg suggested the term “recreancy” to refer to behaviors associated with institutional failures, which he distinguished from the consequences of such failures. This article revisits issues related to recreancy associated with the 1989 Exxon Valdez oil spill. Using qualitative data collected in Cordova, Alaska, between 2002 and 2010, we examine notions about recreancy and technological disasters. Findings highlight

Liesel Ashley Ritchie; Duane A. Gill; Courtney N. Farnham

2012-01-01

232

The Best and the Rest: Revisiting the Norm of Normality of Individual Performance  

ERIC Educational Resources Information Center

|We revisit a long-held assumption in human resource management, organizational behavior, and industrial and organizational psychology that individual performance follows a Gaussian (normal) distribution. We conducted 5 studies involving 198 samples including 633,263 researchers, entertainers, politicians, and amateur and professional athletes.…

O'Boyle, Ernest, Jr.; Aguinis, Herman

2012-01-01

233

Joint remote preparation of four-qubit cluster-type states revisited  

Microsoft Academic Search

We revisit the protocols proposed recently (Zhan et al 2011 J. Phys. B: At. Mol. Opt. Phys. 44 095501) for joint remote preparation of four-qubit cluster-type states. We not only point out errors in those protocols but also make considerable improvements. Our protocols, for both the cases of real and complex coefficients of the state to be prepared, consume much

Nguyen Ba An; Cao Thi Bich; Nung Van Don

2011-01-01

234

Putting Armor Back into the 82nd Airborne Division: Revisiting the AGS Decision.  

National Technical Information Service (NTIS)

The Army Times has reported that the Chief of Staff of the Army, General Peter Schoomaker, has directed the army to pursue more effective organizational structures. Since that is the case, now is the perfect time to revisit the decision to remove armor fr...

A. D. Preston

2004-01-01

235

A Gender Lens on Pedagogical Choice in Academia: Revisiting Hartlaub and Lancaster's Study on Teaching Methodologies  

ERIC Educational Resources Information Center

|This paper focuses on the role of gender in faculty choice of teaching methodologies at colleges and universities in North Carolina. We replicate research conducted by Hartlaub and Lancaster who examined pedagogical preference among a national sample of political science instructors. In revisiting that inquiry, published in 2008, we have explored…

Wigfall, Patricia Moss; Hall, Paula Quick

2010-01-01

236

Revisiting the 'invisible college': José Ramón Mélida in early 20th century Spain  

Microsoft Academic Search

This article revisits the concept of the 'invisible college', defined within the field of History of Science in the 1960s as the informal power groups formed in academia. It is argued that the concept of the 'invisible college' is still valid but should integrate new developments within the social sciences. Thus, the networks formed in the invisible colleges should be

Margarita Díaz-Andreu

237

To Die Laughing and to Laugh at Dying: Revisiting The Awakening  

Microsoft Academic Search

Time has come to reread The Awakening. In new times, it might be worth giving our texts another chance, let them run another risk. We might learn to open our ears to other things, familiar things that nevertheless might ring otherwise. The present reading revisits this well-known novel through a reconsideration of the apparently familiar notion of awakening. An encounter

Anca Parvulescu

2005-01-01

238

Revisiting First-Year College Students' Mattering: Social Support, Academic Stress, and the Mattering Experience  

ERIC Educational Resources Information Center

|In this study, Nancy Schlossberg's (1989) theory of college students' mattering to others was revisited. Mattering is the experience of others depending on us, being interested in us, and being concerned with our fate. The relationships of gender, mattering to college friends and the college environment, and friend and family social support with…

Rayle, Andrea Dixon; Chung, Kuo-Yi

2008-01-01

239

LETTERS AND COMMENTS: Surface tension in soap films: revisiting a classic demonstration  

NASA Astrophysics Data System (ADS)

We revisit a classic demonstration for surface tension in soap films and introduce a more striking variation of it. The demonstration shows how the film, pulling uniformly and normally on a loose string, transforms it into a circular arc under tension. The relationship between the surface tension and the string tension is analysed and presented in a useful graphical form.

Behroozi, F.

2010-01-01

240

Revisiting Interpretation of Canonical Correlation Analysis: A Tutorial and Demonstration of Canonical Commonality Analysis  

ERIC Educational Resources Information Center

In the face of multicollinearity, researchers face challenges interpreting canonical correlation analysis (CCA) results. Although standardized function and structure coefficients provide insight into the canonical variates produced, they fall short when researchers want to fully report canonical effects. This article revisits the interpretation of…

Nimon, Kim; Henson, Robin K.; Gates, Michael S.

2010-01-01

241

Malaria resurgence in the East African highlands: Temperature trends revisited  

PubMed Central

The incidence of malaria in the East African highlands has increased since the end of the 1970s. The role of climate change in the exacerbation of the disease has been controversial, and the specific influence of rising temperature (warming) has been highly debated following a previous study reporting no evidence to support a trend in temperature. We revisit this result using the same temperature data, now updated to the present from 1950 to 2002 for four high-altitude sites in East Africa where malaria has become a serious public health problem. With both nonparametric and parametric statistical analyses, we find evidence for a significant warming trend at all sites. To assess the biological significance of this trend, we drive a dynamical model for the population dynamics of the mosquito vector with the temperature time series and the corresponding detrended versions. This approach suggests that the observed temperature changes would be significantly amplified by the mosquito population dynamics with a difference in the biological response at least 1 order of magnitude larger than that in the environmental variable. Our results emphasize the importance of considering not just the statistical significance of climate trends but also their biological implications with dynamical models.

Pascual, M.; Ahumada, J. A.; Chaves, L. F.; Rodo, X.; Bouma, M.

2006-01-01

242

REVISITING THE THERMAL STABILITY OF RADIATION-DOMINATED THIN DISKS  

SciTech Connect

The standard thin disk model predicts that when the accretion rate is over a small fraction of the Eddington rate, which corresponds to L {approx}> 0.06 L{sub Edd}, the inner region of the disk is radiation-pressure dominated and thermally unstable. However, observations of the high/soft state of black hole X-ray binaries with luminosity well within this regime (0.01L{sub Edd} {approx}< L {approx}< 0.5L{sub Edd}) indicate that the disk has very little variability, i.e., it is quite stable. Recent radiation magnetohydrodynamic simulations of a vertically stratified shearing box have confirmed the absence of the thermal instability. In this paper, we revisit the thermal stability by linear analysis, taking into account the role of magnetic field in the accretion flow. By assuming that the field responds negatively to a positive temperature perturbation, we find that the threshold of accretion rate above which the disk becomes thermally unstable increases significantly compared with the case of not considering the role of magnetic field. This accounts for the stability of the observed sources with high luminosities. Our model also presents a possible explanation as to why only GRS 1915+105 seems to show thermally unstable behavior. This peculiar source holds the highest accretion rate (or luminosity) among the known high state sources, which is well above the accretion rate threshold of the instability.

Zheng Shengming; Gu Weimin; Lu Jufu [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China); Yuan Feng, E-mail: guwm@xmu.edu.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

2011-05-01

243

V838 Monocerotis revisited: Space phenomenon imitates art  

NASA Astrophysics Data System (ADS)

V838 Monocerotis revisited: Space phenomenon imitates art hi-res Size hi-res: 558 Kb Credits: NASA, the Hubble Heritage Team (AURA/STScI) and ESA V838 Monocerotis revisited: Space phenomenon imitates art "Starry Night", Vincent van Gogh's famous painting, is renowned for its bold whorls of light sweeping across a raging night sky. Although this image of the heavens came only from the artist's restless imagination, a new picture from the NASA/ESA Hubble Space Telescope bears remarkable similarities to the van Gogh work, complete with never-before-seen spirals of dust swirling across trillions of kilometres of interstellar space. This image, obtained with the Advanced Camera for Surveys on February 8, 2004, is Hubble's latest view of an expanding halo of light around a distant star, named V838 Monocerotis (V838 Mon). The illumination of interstellar dust comes from the red supergiant star at the middle of the image, which gave off a flashbulb-like pulse of light two years ago. V838 Mon is located about 20,000 light-years away from Earth in the direction of the constellation Monoceros, placing the star at the outer edge of our Milky Way galaxy V838 Monocerotis revisited: Space phenomenon imitates art hi-res Size hi-res: 1989 kb Credits: NASA, the Hubble Heritage Team (AURA/STScI) and ESA V838 Monocerotis revisited: Space phenomenon imitates art "Starry Night", Vincent van Gogh's famous painting, is renowned for its bold whorls of light sweeping across a raging night sky. Although this image of the heavens came only from the artist's restless imagination, a new picture from the NASA/ESA Hubble Space Telescope bears remarkable similarities to the van Gogh work, complete with never-before-seen spirals of dust swirling across trillions of kilometres of interstellar space. This image, obtained with the Advanced Camera for Surveys on February 8, 2004, is Hubble's latest view of an expanding halo of light around a distant star, named V838 Monocerotis (V838 Mon). The illumination of interstellar dust comes from the red supergiant star at the middle of the image, which gave off a flashbulb-like pulse of light two years ago. V838 Mon is located about 20,000 light-years away from Earth in the direction of the constellation Monoceros, placing the star at the outer edge of our Milky Way galaxy This image, obtained with the Advanced Camera for Surveys on 8 February 2004, is Hubble's latest view of an expanding halo of light around a distant star, named V838 Monocerotis (V838 Mon). The illumination of interstellar dust comes from the red supergiant star at the middle of the image, which gave off a flashbulb-like pulse of light two years ago. V838 Mon is located about 20 000 light-years away from Earth in the direction of the constellation Monoceros, placing the star at the outer edge of our Milky Way galaxy. Called a 'light echo', the expanding illumination of a dusty cloud around the star has been revealing remarkable structures ever since the star suddenly brightened for several weeks in early 2002. Though Hubble has followed the light echo in several snapshots, this new image shows swirls or eddies in the dusty cloud for the first time. These eddies are probably caused by turbulence in the dust and gas around the star as they slowly expand away. The dust and gas were likely ejected from the star in a previous explosion, similar to the 2002 event, which occurred some tens of thousands of years ago. The surrounding dust remained invisible and unsuspected until suddenly illuminated by the brilliant explosion of the central star two years ago. The Hubble Space Telescope has imaged V838 Mon and its light echo several times since the star's outburst in January 2002, in order to follow the constantly changing appearance of the dust as the pulse of illumination continues to expand away from the star at the speed of light. During the outburst event, the normally faint star suddenly brightened, becoming 600 000 times more luminous than our Sun. It was thus one of the most luminous stars in the entire Milky Way, until it faded

2004-03-01

244

Revisiting the quantum Szilard engine with fully quantum considerations  

NASA Astrophysics Data System (ADS)

By considering level shifting during the insertion process we revisit the quantum Szilard engine (QSZE) with fully quantum consideration. We derive the general expressions of the heat absorbed from thermal bath and the total work done to the environment by the system in a cycle with two different cyclic strategies. We find that only the quantum information contributes to the absorbed heat, and the classical information acts like a feedback controller and has no direct effect on the absorbed heat. This is the first demonstration of the different effects of quantum information and classical information for extracting heat from the bath in the QSZE. Moreover, when the well width L?? or the temperature of the bath T?? the QSZE reduces to the classical Szilard engine (CSZE), and the total work satisfies the relation W=kBTln2 as obtained by Sang Wook Kim et al. [S.W. Kim, T. Sagawa, S. De Liberato, M. Ueda, Phys. Rev. Lett. 106 (2011) 070401] for one particle case.

Li, Hai; Zou, Jian; Li, Jun-Gang; Shao, Bin; Wu, Lian-Ao

2012-12-01

245

Biogas from Macroalgae: is it time to revisit the idea?  

PubMed Central

The economic and environmental viability of dedicated terrestrial energy crops is in doubt. The production of large scale biomass (macroalgae) for biofuels in the marine environment was first tested in the late 1960’s. The culture attempts failed due to the engineering challenges of farming offshore. However the energy conversion via anaerobic digestion was successful as the biochemical composition of macroalgae makes it an ideal feedstock. The technology for the mass production of macroalgae has developed principally in China and Asia over the last 50 years to such a degree that it is now the single largest product of aquaculture. There has also been significant technology transfer and macroalgal cultivation is now well tried and tested in Europe and America. The inherent advantage of production of biofuel feedstock in the marine environment is that it does not compete with food production for land or fresh water. Here we revisit the idea of the large scale cultivation of macroalgae at sea for subsequent anaerobic digestion to produce biogas as a source of renewable energy, using a European case study as an example.

2012-01-01

246

The Loss-Cone Problem in Dense Nuclei Revisited  

NASA Astrophysics Data System (ADS)

This is the start-up of a project revisiting the star-gas interactions in young, dense galactic nuclei. Here we present some semi-analytic results following ideas given originally by Frank & Rees (1976), Vil'koviski (1976), Hara (1978), Langbein et al. (1990), and references therein. The heating rate of an assumed supermassive central gas-star object due to loss-cone stars, plunging onto it on elongated orbits from outside is calculated taking into account a possible anisotropy of the surrounding stellar distribution. We discuss for a range of central masses the rate of stars on such loss-cone orbits and their heating effect. Here we assume a simplified model of a galactic nucleus consisting of a Plummer model with an embedded density cusp, using stellar point masses. We plan to extend this investigation to numerical studies, allowing a wider range of possible stellar distribution functions and to take into account gas production by stellar collisions and star formation. A more detailed understanding of that early evolutionary phase of galactic nuclei from basic principles is one of the key features presently missing for the link between cosmology and galaxy formation. References: Frank J., Rees M.J., 1976, MNRAS, 176, 633. Hara T., 1978, Prog. Theor. Phys., 60, 711. Langbein, T., Spurzem, R., Fricke, K.J, Yorke, H.W., 1990, A&A, 227, 333. Vil'koviski E., 1976, Sov. Astr. Lett., 1, 137.

Amaro-Seoane, Pau; Spurzem, Rainer

247

A simple theory of the pycnocline and overturning revisited  

NASA Astrophysics Data System (ADS)

A simple theory linking the pycnocline depth and volume transport of the thermohaline overturning to winds, eddies, surface densities and diapycnal diffusion was proposed by Gnanadesikan (Science, 283:2077-2079, 1999). This paper revisits this theory, with eye to understanding which predictions are robust, and which may be limited by the geometric simplification required to derive such a simple theory. We show that the theory works extremely well for diagnostic models, in which surface density is fixed. It thus appears that the model can be used as a diagnostic framework for understanding mechanisms behind circulation changes. The key insight of the theory that the Southern Ocean, rather than the tropics, can serve as a pathway for transformation of dense water to light water is supported by the observed distribution of radiocarbon. However, we demonstrate that changes in forcing do more than simply scale the magnitude of the circulation up and down, producing changes in pycnocline shape and circulation geometry. In particular, the roles of buoyancy forcing and stationary eddies are more complicated than would be expected from the simple theory. Such changes must be taken into account when interpreting measurements at individual locations.

Gnanadesikan, Anand; de Boer, Agatha M.; Mignone, Bryan K.

248

Revisiting the role of magnetic moments in heliospheric plasmas  

NASA Astrophysics Data System (ADS)

The magnetic moment is one of the most fundamental, nontrivial particle properties known in plasma physics. Also known as the first adiabatic invariant, it is conserved under a broad range of microphysical processes and plasma boundary conditions. However, especially in modern numerical simulations, the conservation of this property, which in principle may serve as a control parameter, is no longer used explicitly. In light of this fact, as well as in a recent series of studies of the solar wind termination shock and comparable systems, where this conservation was used as a key ingredient, we now revisit this old, but standing problem. Building on our earlier arguments on when the magnetic moment of individual particles is conserved, we now carefully expand this argument further, studying nontrivial systems, such as systems where individual ions are represented by a broad distribution function that is described with the help of a transport equation. We see that the magnetic moment is conserved under an even wider variety of situations than those studied in earlier publications. When studying systems of purely kinetic equations, the magnetic moment can be converted into an additional force term in the transport equation. We also study the physics that is taken into account in shock simulations and pinpoint weaknesses in the physics used by these modern codes.

Fahr, H.-J.; Siewert, M.

2013-04-01

249

Children's thermoregulation during exercise in the heat: a revisit.  

PubMed

The review revisits some child-adult differences relevant to thermoregulation and offers alternatives to accepted interpretations. Morphologically, children have a higher body surface area to mass ratio -- a major factor in "dry" heat dissipation and effective sweat evaporation. Locomotion-wise, children are less economical than adults, producing more heat per unit body mass. Additionally, children need to divert a greater proportion of their cardiac output to the skin under heat stress. Thus, a larger proportion of their cardiac output is shunted away from the body's core and working muscles -- particularly in hot conditions. Finally, under all environmental conditions and allometric comparisons, children's sweating rates are lower than those of adults. The differences appear to suggest thermoregulatory inferiority, but no epidemiological data show higher heat-injury rates in children, even during heat waves. We suggest that children employ a different thermoregulatory strategy. In extreme temperatures, they may indeed be more vulnerable, but under most ambient conditions they are not necessarily inferior to adults. Children rely more on dry heat dissipation by their larger relative skin surface area than on evaporative heat loss. This also enables them to evaporate sweat more efficiently with the added bonus of conserving water better than adults. PMID:18347699

Falk, Bareket; Dotan, Raffy

2008-04-01

250

Revisiting the role of communication in adolescent intimate partner violence.  

PubMed

A growing literature suggests that communication strategies can promote or inhibit intimate partner violence (IPV). Research on communication is still needed on a group ripe for early IPV intervention: high school-aged adolescents. This article revisits our previous analyses of young female reproductive clinic patients (Messinger, Davidson, & Rickert, 2011) by examining how the adolescent and young adult respondents differ. To explore replicability of the adolescent results across populations, they are compared to 487 adolescent female students sampled from four urban high schools. Across samples, all communication strategies were used more frequently within violent relationships. Multivariate analysis identified escalating strategies used and received as being positively associated with physical violence used and received in all three samples. Regarding verbal reasoning and temporary conflict avoidance, substantial differences appeared between the young adult and adolescent clinic samples, and results from the adolescent clinic sample were largely replicated with the adolescent school sample, suggesting that young adult samples in this literature are not adequate proxies for adolescents. PMID:22491220

Messinger, Adam M; Rickert, Vaughn I; Fry, Deborah A; Lessel, Harriet; Davidson, Leslie L

2012-04-04

251

Nonradial thermal instabilities in the solar core, revisited.  

NASA Astrophysics Data System (ADS)

Mechanisms which produce a mixing in the solar core, based on the original idea of the ``solar spoon'' (Dilke & Gough 1972Natur.240..262D), for explaining the neutrino problem have recently been ruled out by Bahcall & Kumar (1993ApJ...409L..73B). We therefore revisit the original work of Rosenbluth & Bahcall (1973ApJ...184....9R) on the nonspherical thermal instabilities in the solar core, introducing some improvements. The authors found that their solar model was stable against these perturbations and they concluded that the turbulence in the solar core appeared unlikely to be the explanation of the lack of solar neutrinos. Our analysis is motived by the fact that the updated standard solar models are sensibly different from those used in the 70's, and therefore instabilities of the kind postulated by Rosenbluth & Bahcall might be excited. However our results fully confirm the previous ones that the present Sun is stable against nonradial thermal disturbances, at least in the linear analysis, therefore no solutions for growing thermal modes are possible. The confirmation of the stability of the solar core against the mixing and the impressive agreement of the standard solar models with helioseismic data indicate that the present neutrino problem is not astrophysical in origin but it relies upon non standard neutrino properties.

Paterno, L.; Rapisarda, L.; di Mauro, M. P.

1997-06-01

252

The significance of the integrated Sachs-Wolfe effect revisited  

NASA Astrophysics Data System (ADS)

We revisit the state of the integrated Sachs-Wolfe (ISW) effect measurements in light of newly available data and address criticisms about the measurements which have recently been raised. We update the data set previously assembled by Giannantonio et al. to include new data releases for both the cosmic microwave background and the large-scale structure of the Universe. We find that our updated results are consistent with previous measurements. By fitting a single template amplitude, we now obtain a combined significance of the ISW detection at the 4.4? level, which fluctuates by ˜0.4? when alternative data cuts and analysis assumptions are considered. We also make new tests for systematic contaminations of the data, focusing in particular on the issues raised by Sawangwit et al. Amongst them, we address the rotation test, which aims at checking for possible systematics by correlating pairs of randomly rotated maps. We find results consistent with the expected data covariance, no evidence for enhanced correlation on any preferred axis of rotation, and therefore no indication of any additional systematic contamination. We publicly release the results, the covariance matrix and the sky maps used to obtain them.

Giannantonio, Tommaso; Crittenden, Robert; Nichol, Robert; Ross, Ashley J.

2012-11-01

253

Prediction of post-surgical seizure outcome in left mesial temporal lobe epilepsy?  

PubMed Central

Mesial temporal lobe epilepsy is the most common type of focal epilepsy and in its course often becomes refractory to anticonvulsant pharmacotherapy. A resection of the mesial temporal lobe structures is a promising option in these cases. However, approximately 30% of all patients remain with persistent seizures after surgery. In other words, reliable criteria for patients' outcome prediction are absent. To address this limitation, we investigated pre-surgical brain morphology of patients with unilateral left mesial temporal lobe epilepsy who underwent a selective amygdalohippocampectomy. Using support vector classification, we aimed to predict the post-surgical seizure outcome of each patient based on the pre-surgical T1-weighted structural brain images. Due to morphological gender differences and the evidence that men and women differ in onset, prevalence and symptomology in most neurological diseases, we investigated male and female patients separately. Thus, we benefitted from the capability to validate the reliability of our method in two independent samples. Notably, we were able to accurately predict the individual patients' outcome in the male (94% balanced accuracy) as well as in the female (96% balanced accuracy) group. In the male cohort relatively larger white matter volumes in the favorable as compared to the non-favorable outcome group were identified bilaterally in the cingulum bundle, fronto-occipital fasciculus and both caudate nuclei, whereas the left inferior longitudinal fasciculus showed relatively larger white matter volume in the non-favorable group. While relatively larger white matter volumes in the female cohort in the left inferior and right middle longitudinal fasciculus were associated with the favorable outcome, relatively larger white matter volumes in the non-favorable outcome group were identified bilaterally in the superior longitudinal fasciculi I and II. Here, we observed a clear lateralization and distinction of structures involved in the classification in men as compared to women with men exhibiting more alterations in the hemisphere contralateral to the seizure focus. In conclusion, individual post-surgical outcome predictions based on a single T1-weighted magnetic resonance image seem plausible and may thus support the routine pre-surgical workup of epilepsy patients.

Feis, Delia-Lisa; Schoene-Bake, Jan-Christoph; Elger, Christian; Wagner, Jan; Tittgemeyer, Marc; Weber, Bernd

2013-01-01

254

Derivation of a nomogram to estimate probability of revisit in at-risk older adults discharged from the emergency department.  

PubMed

Estimation of the risk of revisit to the emergency department (ED) soon after discharge in the older population may assist discharge planning and targeting of post discharge intervention in high risk patients. In this study we sought to derive a risk prediction calculator for this purpose. In a prospective observational study in two tertiary ED, we conducted a comprehensive assessment of people aged 65 and over, and followed them for a minimum of 28 days post discharge. Cox proportional hazard models relating any unplanned ED revisit in the follow up period to observed risk factors were used to compute a probability nomogram. From 1,439 patients, 189 (13.1 %) had at least one unplanned revisit within 28 days. Revisit probability was weighted towards chronic and difficult to modify risk factors such as depression, malignancy and cognitive impairment. We conclude that the risk of revisit post discharge is calculable using a probability nomogram. However, revisit is largely related to immutable factors reflecting chronic illness burden, and does not necessarily reflect poor ED care during the initial index presentation. PMID:23462889

Arendts, Glenn; Fitzhardinge, Sarah; Pronk, Karren; Hutton, Marani; Nagree, Yusuf; Donaldson, Mark

2013-03-05

255

Management of 46, XY partial gonadal dysgenesis--revisited.  

PubMed

46, XY partial gonadal dysgenesis is a rare condition characterized by a varying degree of testicular dysgenesis, ambiguous genitalia, and usually absence of regression of Müllerian structures. The management of patients with these disorders warrants revisiting, owing to recent molecular biological findings and to reports on the long-term outcome of individuals with ambiguous genitalia. We report on a patient with 46, XY chromosomes, presence of the "sex-determining region of Y chromosome" (SRY) gene, scrotal gonads, fallopain tubes, uterus, vagina, and ambiguous genitalia with a penisoid, perineal hypospadia and sinus urogenitalis. Gonadal biopsy revealed virtually normal testicular tissue in both gonads. Removal of the gonads during surgery for a cystic adnex tumor revealed clear signs of partial gonadal dysgenesis. The decision to raise the child as a male was made by parents and physicians caring for the patient. Administration of testosterone, removal of the uterus and adnexes, in addition to repair of the hypospadia permitted an almost normal penis to be formed with normal male micturition. In the management of affected patients it has to be considered that establishing the diagnosis may be extremely tricky, even with the use of gonadal biopsies. The decision on sex assignment may be even more difficult, since future gender identity, limitations of genital reconstructive surgery and the potential for development of gonadal tumors have to be taken into consideration. While in the past, female sex assignment was commonly recommended for such patients, raising them in a male gender role is now considered. Parents should be involved in the decision that is ultimately based on extensive analysis of the individual case. PMID:12422582

Crone, Julia; Amann, Gabriele; Gheradini, Rainer; Kirchlechner, Veronika; Fékété, Claire-Nihoul

2002-06-28

256

REVISITING ACCELERATION OF CHARGED GRAINS IN MAGNETOHYDRODYNAMIC TURBULENCE  

SciTech Connect

We study the acceleration of charged grains by magnetohydrodynamic (MHD) turbulence in the interstellar medium (ISM). We begin with revisiting gyroresonance acceleration by taking into account the fluctuations of grain guiding center along a uniform magnetic field (i.e., nonlinear theory-NLT). We calculate grain velocities due to gyroresonance by fast MHD modes using the NLT for different phases of the ISM and compare them with results obtained using quasi-linear theory (QLT). We find for the parameters applicable to the typical ISM phases that the fluctuations of the grain guiding center reduce grain velocities by less than 15%, but they can be important for more special circumstances. We confirm that large grains can be accelerated to super-Alfvenic velocities through gyroresonance. For such super-Alfvenic grains, we investigate the effect of further acceleration via transit-time damping (TTD) by fast modes. We find that due to the broadening of the resonance condition in the NLT, the TTD acceleration is not only important for the cosines of grain pitch angle relative to the magnetic field {mu} > V{sub A}/v, but also for {mu} < V{sub A}/v where v is the grain velocity and V{sub A} is the Alfven speed. We show that the TTD acceleration is dominant over the gyroresonance for large grains, and can increase substantially grain velocities induced by gyroresonance acceleration. We quantify another stochastic acceleration mechanism arising from low-frequency Alfven waves. We discuss the range of applicability of the mechanisms and their implications.

Hoang, Thiem; Lazarian, A. [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States); Schlickeiser, R. [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

2012-03-01

257

Revisiting evidence for sustainability of bushmeat hunting in West Africa.  

PubMed

Bushmeat hunting, a key source of dietary protein, has been implicated as a major extinction threat to tropical vertebrate species in West Africa. Ideally, any such hunting of wild species should be done sustainably, with off-take levels low enough to ensure viability of harvested species. Recent work purports to show that a mature bushmeat market in a major city in Ghana operates sustainably after depletion of vulnerable, slow-reproducing species (Cowlishaw and others 2005). I revisit two aspects of this work. First, I retest the prediction that larger species are transported to the market from greater distances, as expected if overexploitation depletes large species close to the city. Cowlishaw and others failed to find a significantly positive relationship between species-specific body mass and distance between capture site and the market. However, my reanalysis provides evidence for a positive relationship after all, consistent with unsustainable harvesting. In particular, ungulate species were harvested significantly farther from the market than smaller-bodied rodent species. Second, I caution that just because species "persist" in the marketplace in no way implies that they can withstand hunting pressure elsewhere and so should be of little concern to conservationists. I reveal that such species, despite their high intrinsic rates of population growth, are not robust elsewhere. Several of them have disappeared from a network of protected areas in Ghana (Brashares and others 2001). I show that faster-reproducing species are not necessarily more likely to persist in protected areas. The mere presence of fast-reproducing species in a mature bushmeat market should not be construed as generalizable robustness; criteria for ecological sustainability should ensure viability; and harvested species should be robust, not highly prone to extinction, in protected areas. PMID:17638049

Waite, T A

2007-07-18

258

Revisiting four scientific debates in ocean acidification research  

NASA Astrophysics Data System (ADS)

In recent years, ocean acidification has gained continuously increasing attention from scientists and a number of stakeholders and has raised serious concerns about its effects on marine organisms and ecosystems. With the increase in interest, funding resources, and the number of scientific investigations focusing on this environmental problem, increasing amounts of data and results have been produced, and a progressively growing and more rigorous understanding of this problem has begun to develop. Nevertheless, there are still a number of scientific debates, and in some cases misconceptions, that keep reoccurring at a number of forums in various contexts. In this article, we revisit four of these topics that we think require further thoughtful consideration including: (1) surface seawater CO2 chemistry in shallow water coastal areas, (2) experimental manipulation of marine systems using CO2 gas or by acid addition, (3) net versus gross calcification and dissolution, and (4) CaCO3 mineral dissolution and seawater buffering. As a summation of these topics, we emphasize that: (1) many coastal environments experience seawater pCO2 that is significantly higher than expected from equilibrium with the atmosphere and is strongly linked to biological processes; (2) addition of acid, base or CO2 gas to seawater can all be useful techniques to manipulate seawater chemistry in ocean acidification experiments; (3) estimates of calcification or CaCO3 dissolution based on present techniques are measuring the net of gross calcification and dissolution; and (4) dissolution of metastable carbonate mineral phases will not produce sufficient alkalinity to buffer the pH and carbonate saturation state of shallow water environments on timescales of decades to hundreds of years to the extent that any potential negative effects on marine calcifiers will be avoided.

Andersson, A. J.; MacKenzie, F. T.

2012-03-01

259

Revisiting theories with enhanced Higgs couplings to weak gauge bosons  

NASA Astrophysics Data System (ADS)

Based on recent LHC Higgs analyses and in anticipation of future results we revisit theories where Higgs bosons can couple to weak gauge bosons with enhanced strength relative to the Standard Model value. Specifically, we look at the Georgi-Machacek model and its generalizations where higher “spin” representations of SU(2)L break electroweak symmetry while maintaining custodial SU(2). In these theories, there is not only a Higgs-like boson but partner Higgs scalars transforming under representations of custodial SU(2), leading to a rich phenomenology. These theories serve as a consistent theoretical and experimental framework to explain enhanced couplings to gauge bosons, including fermiophobic Higgses. We focus on the phenomenology of a neutral scalar partner to the Higgs, which is determined once the Higgs couplings are specified. Depending on the parameter space, this partner could have (i) enhanced fermion and gauge boson couplings and should be searched for at high mass (>600GeV), (ii) suppressed couplings and could be searched for at lower masses, where the Standard Model Higgs has already been ruled out, and (iii) fermiophilic couplings, where it can be searched for in heavy Higgs and top resonance searches. In the first two regions, the partner also has substantial decay rates into a pair of Higgs bosons. We touch briefly on the more model-dependent effects of the nontrivial SU(2)C multiplets, which have exotic signals, such as a doubly charged Higgs. We also discuss how the loop induced effects of these scalars tend to reduce the Higgs decay rate to photons, adding an additional uncertainty when extracting the couplings for the Higgs boson.

Chang, Spencer; Newby, Christopher A.; Raj, Nirmal; Wanotayaroj, Chaowaroj

2012-11-01

260

Photoevaporation of Circumstellar Disks Revisited: The Dust-free Case  

NASA Astrophysics Data System (ADS)

Photoevaporation by stellar ionizing radiation is believed to play an important role in the dispersal of disks around young stars. The mass-loss model for dust-free disks developed by Hollenbach et al. is currently regarded as the conventional one and has been used in a wide variety of studies. However, the rate in this model was derived using the crude so-called 1+1D approximation of ionizing radiation transfer, which assumes that diffuse radiation propagates in a direction vertical to the disk. In this study, we revisit the photoevaporation of dust-free disks by solving the two-dimensional axisymmetric radiative transfer for steady-state disks. Unlike that solved by the conventional model, we determine that direct stellar radiation is more important than the diffuse field at the disk surface. The radial density distribution at the ionization boundary is represented by a single power law with index –3/2 in contrast to the conventional double power law. For this distribution, the photoevaporation rate from the entire disk can be written as a function of the ionizing photon emissivity ?EUV from the central star and the disk outer radius r d as follows: \\dot{M}_PE = 5.4 \\times 10^{-5} (\\Phi _EUV/10^{49}\\ s^{-1})^{1/2} (r_d/1000\\ AU)^{1/2} \\ M_\\odot \\ yr^{-1}. This new rate depends on the outer disk radius rather than on the gravitational radius as in the conventional model, because of the enhanced contribution to the mass loss from the outer disk annuli. In addition, we discuss its applications to present-day as well as primordial star formation.

Tanaka, Kei E. I.; Nakamoto, Taishi; Omukai, Kazuyuki

2013-08-01

261

The cholinergic system in mild cognitive impairment and Alzheimer's disease: an in vivo MRI and DTI study.  

PubMed

Few studies have investigated in vivo changes of the cholinergic basal forebrain in Alzheimer's disease (AD) and amnestic mild cognitive impairment (MCI), an at risk stage of AD. Even less is known about alterations of cortical projecting fiber tracts associated with basal forebrain atrophy. In this study, we determined regional atrophy within the basal forebrain in 21 patients with AD and 16 subjects with MCI compared to 20 healthy elderly subjects using deformation-based morphometry of MRI scans. We assessed effects of basal forebrain atrophy on fiber tracts derived from high-resolution diffusion tensor imaging (DTI) using tract-based spatial statistics. We localized significant effects relative to a map of cholinergic nuclei in MRI standard space as determined from a postmortem brain. Patients with AD and MCI subjects showed reduced volumes in basal forebrain areas corresponding to anterior medial and lateral, intermediate and posterior nuclei of the Nucleus basalis of Meynert (NbM) as well as in the diagonal band of Broca nuclei (P < 0.01). Effects in MCI subjects were spatially more restricted than in AD, but occurred at similar locations. The volume of the right antero-lateral NbM nucleus was correlated with intracortical projecting fiber tract integrity such as the corpus callosum, cingulate, and the superior longitudinal, inferior longitudinal, inferior fronto-occipital, and uncinate fasciculus (P < 0.05, corrected for multiple comparisons). Our findings suggest that a multimodal MRI-DTI approach is supportive to determine atrophy of cholinergic nuclei and its effect on intracortical projecting fiber tracts in AD. PMID:20672311

Teipel, Stefan J; Meindl, Thomas; Grinberg, Lea; Grothe, Michel; Cantero, Jose L; Reiser, Maximilian F; Möller, Hans-Jürgen; Heinsen, Helmut; Hampel, Harald

2010-07-29

262

White Matter Abnormalities in Pediatric Obsessive-Compulsive Disorder  

PubMed Central

Obsessive-compulsive disorder (OCD) is a prevalent and often severely disabling illness with onset generally in childhood or adolescence. Although white matter deficits have been implicated in the neurobiology of OCD, few studies have been conducted in pediatric patients when the brain is still developing and have examined their functional correlates. In this study, 23 pediatric OCD patients and 23 healthy volunteers, between the ages of 9 and 17 years, matched for sex, age, handedness, and IQ, received a diffusion tensor imaging exam on a 3T GE system and a brief neuropsychological battery tapping executive functions. Patient symptom severity was assessed using the Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS). Patients with OCD exhibited significantly greater fractional anisotropy compared to matched controls in the left dorsal cingulum bundle, splenium of the corpus callosum, right corticospinal tract, and left inferior fronto-occipital fasciculus. There were no regions of significantly lower fractional anisotropy in patients compared to controls. Higher fractional anisotropy in the splenium was significantly correlated with greater obsession severity on the CY-BOCS in the subgroup of psychotropic drug-naïve patients. Among patients, there was a significant association between greater fractional anisotropy in the dorsal cingulum bundle and better performance on measures of response inhibition and cognitive control. The overall findings suggest a pattern of greater directional coherence of white matter tracts in OCD very early in the course of illness, which may serve a compensatory mechanism, at least for response inhibition functions typically subserved by the cingulum bundle.

Gruner, Patricia; Vo, An; Ikuta, Toshikazu; Mahon, Katie; Peters, Bart D; Malhotra, Anil K; Ulug, Aziz M; Szeszko, Philip R

2012-01-01

263

Genetics of brain fiber architecture and intellectual performance.  

PubMed

The study is the first to analyze genetic and environmental factors that affect brain fiber architecture and its genetic linkage with cognitive function. We assessed white matter integrity voxelwise using diffusion tensor imaging at high magnetic field (4 Tesla), in 92 identical and fraternal twins. White matter integrity, quantified using fractional anisotropy (FA), was used to fit structural equation models (SEM) at each point in the brain, generating three-dimensional maps of heritability. We visualized the anatomical profile of correlations between white matter integrity and full-scale, verbal, and performance intelligence quotients (FIQ, VIQ, and PIQ). White matter integrity (FA) was under strong genetic control and was highly heritable in bilateral frontal (a(2)=0.55, p=0.04, left; a(2)=0.74, p=0.006, right), bilateral parietal (a(2)=0.85, p<0.001, left; a(2)=0.84, p<0.001, right), and left occipital (a(2)=0.76, p=0.003) lobes, and was correlated with FIQ and PIQ in the cingulum, optic radiations, superior fronto-occipital fasciculus, internal capsule, callosal isthmus, and the corona radiata (p=0.04 for FIQ and p=0.01 for PIQ, corrected for multiple comparisons). In a cross-trait mapping approach, common genetic factors mediated the correlation between IQ and white matter integrity, suggesting a common physiological mechanism for both, and common genetic determination. These genetic brain maps reveal heritable aspects of white matter integrity and should expedite the discovery of single-nucleotide polymorphisms affecting fiber connectivity and cognition. PMID:19228974

Chiang, Ming-Chang; Barysheva, Marina; Shattuck, David W; Lee, Agatha D; Madsen, Sarah K; Avedissian, Christina; Klunder, Andrea D; Toga, Arthur W; McMahon, Katie L; de Zubicaray, Greig I; Wright, Margaret J; Srivastava, Anuj; Balov, Nikolay; Thompson, Paul M

2009-02-18

264

Fiber tract-specific white matter lesion severity Findings in late-life depression and by AGTR1 A1166C genotype.  

PubMed

Past work demonstrated that late-life depression is associated with greater severity of ischemic cerebral hyperintense white matter lesions, particularly frontal lesions. However, these lesions are also associated with other neuropsychiatric deficits, so these clinical relationships may depend on which fiber tracts are damaged. We examined the ratio of lesion to nonlesioned white matter tissue within multiple fiber tracts between depressed and nondepressed elders. We also sought to determine if the AGTR1 A1166C and BDNF Val66Met polymorphisms contributed to vulnerability to lesion development in discrete tracts. The 3T structural MR images and blood samples for genetic analyses were acquired on 54 depressed and 37 nondepressed elders. Lesion maps were created through an automated tissue segmentation process and applied to a probabilistic white matter fiber tract atlas allowing for identification of the fraction of the tract occupied by lesion. The depressed cohort exhibited a significantly greater lesion ratio only in the left upper cingulum near the cingulate gyrus (F((1,86)) = 4.62, P = 0.0344), supporting past work implicating cingulate dysfunction in the pathogenesis of depression. In the 62 Caucasian subjects with genetic data, AGTR1 C1166 carriers exhibited greater lesion ratios across multiple tracts including the anterior thalamic radiation and inferior fronto-occipital fasciculus. In contrast, BDNF Met allele carriers exhibited greater lesion ratios only in the frontal corpus callosum. Although these findings did not survive correction for multiple comparisons, this study supports our hypothesis and provides preliminary evidence that genetic differences related to vascular disease may increase lesion vulnerability differentially across fiber tracts. PMID:22021115

Taylor, Warren D; Zhao, Zheen; Ashley-Koch, Allison; Payne, Martha E; Steffens, David C; Krishnan, Ranga R; Hauser, Elizabeth; MacFall, James R

2011-10-22

265

Abnormal White Matter Integrity in Adolescents with Internet Addiction Disorder: A Tract-Based Spatial Statistics Study  

PubMed Central

Background Internet addiction disorder (IAD) is currently becoming a serious mental health issue around the globe. Previous studies regarding IAD were mainly focused on associated psychological examinations. However, there are few studies on brain structure and function about IAD. In this study, we used diffusion tensor imaging (DTI) to investigate white matter integrity in adolescents with IAD. Methodology/Principal Findings Seventeen IAD subjects and sixteen healthy controls without IAD participated in this study. Whole brain voxel-wise analysis of fractional anisotropy (FA) was performed by tract-based spatial statistics (TBSS) to localize abnormal white matter regions between groups. TBSS demonstrated that IAD had significantly lower FA than controls throughout the brain, including the orbito-frontal white matter, corpus callosum, cingulum, inferior fronto-occipital fasciculus, and corona radiation, internal and external capsules, while exhibiting no areas of higher FA. Volume-of-interest (VOI) analysis was used to detect changes of diffusivity indices in the regions showing FA abnormalities. In most VOIs, FA reductions were caused by an increase in radial diffusivity while no changes in axial diffusivity. Correlation analysis was performed to assess the relationship between FA and behavioral measures within the IAD group. Significantly negative correlations were found between FA values in the left genu of the corpus callosum and the Screen for Child Anxiety Related Emotional Disorders, and between FA values in the left external capsule and the Young's Internet addiction scale. Conclusions Our findings suggest that IAD demonstrated widespread reductions of FA in major white matter pathways and such abnormal white matter structure may be linked to some behavioral impairments. In addition, white matter integrity may serve as a potential new treatment target and FA may be as a qualified biomarker to understand the underlying neural mechanisms of injury or to assess the effectiveness of specific early interventions in IAD.

Qin, Lindi; Zhao, Zhimin; Xu, Jianrong; Lei, Hao

2012-01-01

266

Cerebral correlates of visuospatial neglect: A direct cerebral stimulation study.  

PubMed

OBJECTIVE.: To assess the role of the superior longitudinal fascicle, the inferior fronto-occipital fascicle, and the posterior parietal lobe in visuospatial attention in humans during awake brain surgery. EXPERIMENTAL DESIGN.: Seven patients with hemispheric gliomas (six in the right hemisphere) entered the study. During surgery in asleep/awake anesthesia, guided by Diffusion Tensor Imaging Fiber Tractography, visuospatial neglect was assessed during direct electrical stimulation by computerized line bisection. PRINCIPAL OBSERVATIONS.: A rightward deviation, indicating left visuospatial neglect, was induced in six of seven patients by stimulation of the parietofrontal connections, in a location consistent with the trajectory of the second branch of the superior longitudinal fascicle. Stimulation of the medial and dorsal white matter of the superior parietal lobule (corresponding to the first branch of the superior longitudinal fascicle), of the ventral and lateral white matter of the supramarginal gyrus (corresponding to the third branch of the superior longitudinal fascicle), and of the inferior occipitofrontal fasciculus, was largely ineffective. Stimulation of the superior parietal lobule (Brodmann's area 7) caused a marked rightward deviation in all of the six assessed patients, while stimulation of Brodmann's areas 5 and 19 was ineffective. CONCLUSIONS.: The parietofrontal connections of the dorso-lateral fibers of the superior longitudinal fascicle (i.e., the second branch of the fascicle), and the posterior superior parietal lobe (Brodmann's area 7) are involved in the orientation of spatial attention. Spatial neglect should be assessed systematically during awake brain surgery, particularly when the right parietal lobe may be involved by the neurosurgical procedure. Hum Brain Mapp, 2013. © 2013 Wiley Periodicals, Inc. PMID:23417885

Vallar, Giuseppe; Bello, Lorenzo; Bricolo, Emanuela; Castellano, Antonella; Casarotti, Alessandra; Falini, Andrea; Riva, Marco; Fava, Enrica; Papagno, Costanza

2013-02-18

267

Brain white matter microstructure is associated with susceptibility to motion-induced nausea.  

PubMed

Nausea is associated with significant morbidity, and there is a wide range in the propensity of individuals to experience nausea. The neural basis of the heterogeneity in nausea susceptibility is poorly understood. Our previous functional magnetic resonance imaging (fMRI) study in healthy adults showed that a visual motion stimulus caused activation in the right MT+/V5 area, and that increased sensation of nausea due to this stimulus was associated with increased activation in the right anterior insula. For the current study, we hypothesized that individual differences in visual motion-induced nausea are due to microstructural differences in the inferior fronto-occipital fasciculus (IFOF), the white matter tract connecting the right visual motion processing area (MT+/V5) and right anterior insula. To test this hypothesis, we acquired diffusion tensor imaging data from 30 healthy adults who were subsequently dichotomized into high and low nausea susceptibility groups based on the Motion Sickness Susceptibility Scale. We quantified diffusion along the IFOF for each subject based on axial diffusivity (AD); radial diffusivity (RD), mean diffusivity (MD) and fractional anisotropy (FA), and evaluated between-group differences in these diffusion metrics. Subjects with high susceptibility to nausea rated significantly (P < 0.001) higher nausea intensity to visual motion stimuli and had significantly (P < 0.05) lower AD and MD along the right IFOF compared to subjects with low susceptibility to nausea. This result suggests that differences in white matter microstructure within tracts connecting visual motion and nausea-processing brain areas may contribute to nausea susceptibility or may have resulted from an increased history of nausea episodes. PMID:23360260

Napadow, V; Sheehan, J; Kim, J; Dassatti, A; Thurler, A H; Surjanhata, B; Vangel, M; Makris, N; Schaechter, J D; Kuo, B

2013-01-29

268

Preliminary transport analysis for P06, A10 and I4+I3 revisits (BEAGLE2003)  

NASA Astrophysics Data System (ADS)

Mass and heat transports across all P06, A10 and I4+I3 were analyzed together based on both revisit data prepared by BEAGLE2003 Expedition and original data during WOCE period. Transports were estimated using an inverse model with 25 neutral density categories. Constraints for calculations were rather simple, i.e., the mass conservation for whole water column, no net mass flux into a basin at deeper layers than the deepest shill located in the north of the observation line, the salt conservation for whole water column and 4Sv of the northward transport between the Rio Grande Rise and the S. American continent. Initial `levels of no motion' were given a priori from vertical profiles of salt and DO. Ekman transports were estimated using NCEP re-analysis data both for the revisit and the original WOCE periods, respectively. Finally, overturn structures especially in the Indian and the Pacific were examined by applying several mass transport values of ITF and we selected solutions which included ITF transport of 15Sv as basic ones for revisit and original WOCE data. Results from present analysis for original WOCE data show good agreements with those from published inverse analyses in the mass and the heat transports. As for results from the analysis with revisit data, a 5 Sv larger (3 Sv smaller) deep overturn is estimated for the Indian (the Pacific) than those with original WOCE data. On the other hand, 5 Sv smaller overturns are estimated both for intermediate and shallower ones in the Pacific-Indian system. As the result, the geostrophic heat flux during the revisit period is estimated to be 0.08 PW which is significantly smaller than that of 0.20 PW during WOCE period. However, the Ekman heat transports compensate geostrophic fluxes, and total heat transports during the revisit and WOCE period turn out to be almost the same value as -0.84+/-0.32 PW and -0.82+/- 0.31 PW, respectively.

Fukasawa, M.; Watanabe, S.; Yoshikawa, Y.; Uchida, H.; Schneider, W.; Kawano, T.; Kaneko, I.; Doi, T.; Ozawa, S.

2004-12-01

269

Preliminary transport analysis for P06, A10 and I4+I3 revisits (BEAGLE2003)  

Microsoft Academic Search

Mass and heat transports across all P06, A10 and I4+I3 were analyzed together based on both revisit data prepared by BEAGLE2003 Expedition and original data during WOCE period. Transports were estimated using an inverse model with 25 neutral density categories. Constraints for calculations were rather simple, i.e., the mass conservation for whole water column, no net mass flux into a

M. Fukasawa; S. Watanabe; Y. Yoshikawa; H. Uchida; W. Schneider; T. Kawano; I. Kaneko; T. Doi; S. Ozawa

2004-01-01

270

Direct synthesis of 1,5-disubstituted-4-magnesio-1,2,3-triazoles, revisited.  

PubMed

After revisiting earlier works reporting the regioselective synthesis of 1,5-disubstituted-1,2,3-triazoles via the addition of bromomagnesium acetylides to azides, much improved yields of the products were obtained for a wide array of azides and alkynes. The intermediates of that reaction can be trapped with different electrophiles to regioselectively form 1,4,5-trisubstituted 1,2,3-triazoles. [reaction: see text] PMID:15070306

Krasi?ski, Antoni; Fokin, Valery V; Sharpless, K Barry

2004-04-15

271

The Merton Theorem Revisited and Restated: Conservatism and Fascism as Functional Analogues  

Microsoft Academic Search

The paper revisits and restates the Merton Theorem of American religious conservatism (Puritanism) and European fascism (Nazism)\\u000a as functional analogues. The original formulation the Merton Theorem identifies and describes them as functional analogues\\u000a in nativism or nationalism through exclusion of and aggression against non-native out-groups. The paper offers an extended\\u000a restatement of the Merton Theorem in which American conservatism and

Milan Zafirovski

2010-01-01

272

Revisiting "Who gets care?": health equity as an arena for nursing action.  

PubMed

This article revisits and reaffirms Patricia Steven's earlier work on access to healthcare as an important arena for nursing action. Many of the conditions that affect access to healthcare, such as racism and oppression, also shape inequities in health outcomes. We propose a conceptualization of social justice that is consistent with addressing the conditions that influence health inequities. We also discuss the implications of a critical and feminist conception of social justice for nursing action, education, practice, research, and policy. PMID:19461229

Pauly, Bernadette M; MacKinnon, Karen; Varcoe, Colleen

273

Cacao Diseases: Important Threats to Chocolate Production Worldwide Cacao Diseases—The Trilogy Revisited  

Microsoft Academic Search

Evans, H. C. 2007. Cacao diseases—The trilogy revisited. Phytopathol- ogy 97:1640-1643. This paper reviews the significant advances by the diseases themselves, as well as by the scientists, in the intervening period since the disease trilogy was first delimited in 1989. The impact of these diseases, black pod, witches' broom, and frosty pod rot, has increased dramatically. In addition, there have

Harry C. Evans

274

Kidney-specific chromosome transfer in genetic hypertension: The Dahl hypothesis revisited  

Microsoft Academic Search

Kidney-specific chromosome transfer in genetic hypertension: The Dahl hypothesis revisited.BackgroundA central dogma in the field of essential hypertension research is that the genetic transmission of increased blood pressure is determined solely by the genotype of the kidney. This concept is based in large part on studies in experimental rat models of spontaneous hypertension in which transplantation of a kidney from

Paul C Churchill; Monique C Churchill; Anil K Bidani; Theodore W Kurtz

2001-01-01

275

Ytterholmen revisited - implications for the Late Wenlock stratigraphy of Gotland and coeval extinctions  

Microsoft Academic Search

Calner, M., Jeppsson, L. & Eriksson, M. J., 2004: Ytterholmen revisited - implications for the Late Wenlock stratigraphy of Gotland and coeval extinctions. GFF, Vol. 126 (Pt. 2, June), pp. 231-241. Stockholm. ISSN 1103-5897. Abstract: The latest Cyrtograptus lundgreni graptolite Chron (Late Wenlock, middle Silurian) is charac- terized globally by the Mulde Event faunal extinctions and glacio-eustatic sea-level change. Only

M. Calner; L. Jeppsson; M. J. Eriksson

2004-01-01

276

The User Model and Context Ontology GUMO Revisited for Future Web 2.0 Extensions  

Microsoft Academic Search

We revisit the top-level ontology Gumo for the uniform man- agement of user and context models in a semantic web environment. We discuss design decisions, while putting the focus on ontological is- sues. The structural integration into user model servers, especially into the U2M-UserModel&ContextService, is also presented. We show ubiq- uitous applications using the user model ontology Gumo together with

Dominik Heckmann; Eric Schwarzkopf; Junichiro Mori; Dietmar Dengler; Alexander Kröner

2007-01-01

277

DeBeauvoir’s Second sex Revisited with Michele Le Doeuff  

Microsoft Academic Search

This paper revisits Simone DeBeauvoir’s Second Sex (1953) with the aid of Michèle Le Doeuff’s analysis of pictorial or imaginary elements in philosophical texts. In her research Le Doeuff takes a central interest in the imaginaire. In The Philosophical Imaginary (1980) she identifies throughout the history of philosophy images which were being presented by their authors as merely ornamental, marginal

Ruth Burch

2011-01-01

278

Second-order elliptic integro-differential equations: viscosity solutions' theory revisited  

Microsoft Academic Search

The aim of this work is to revisit viscosity solutions' theory for second-order elliptic integro-differential equations and to provide a general framework which takes into account solutions with arbitrary growth at infinity. Our main contribution is a new Jensen–Ishii's lemma for integro-differential equations, which is stated for solutions with no restriction on their growth at infinity. The proof of this

Guy Barlesand; Cyril Imbert

2008-01-01

279

Joint remote preparation of four-qubit cluster-type states revisited  

NASA Astrophysics Data System (ADS)

We revisit the protocols proposed recently (Zhan et al 2011 J. Phys. B: At. Mol. Opt. Phys. 44 095501) for joint remote preparation of four-qubit cluster-type states. We not only point out errors in those protocols but also make considerable improvements. Our protocols, for both the cases of real and complex coefficients of the state to be prepared, consume much less quantum resource as well as classical communication cost.

An, Nguyen Ba; Thi Bich, Cao; Van Don, Nung

2011-07-01

280

Something Old, Something New: Revisiting Competing Hypotheses of the Victimization-Offending Relationship Among Adolescents  

Microsoft Academic Search

This study revisits a familiar question regarding the relationship between victimization and offending. Using longitudinal\\u000a data on middle- and high-school students, the study examines competing arguments regarding the relationship between victimization\\u000a and offending embedded within the “dynamic causal” and “population heterogeneity” perspectives. The analysis begins with models\\u000a that estimate the longitudinal relationship between victimization and offending without accounting for the

Graham C. Ousey; Pamela Wilcox; Bonnie S. Fisher

2011-01-01

281

Revisit the Analog Computer and Gradient-Based Neural System for Matrix Inversion  

Microsoft Academic Search

As inspired by revising (Zhang and Ge, 2003), the traditional gradient-based neural system (also termed analog computer (Manherz et al., 1968)) for matrix inversion is re-visited by examining different activation functions and various implementation errors. A general neural system for matrix inversion is thus presented which can be constructed by using monotonically-increasing odd activation functions. For superior convergence and robustness

Yunong Zhang

2005-01-01

282

Children’s social play sequence: Parten’s classic theory revisited  

Microsoft Academic Search

The purpose of this article is to revisit Parten’s study on social play from cultural, environmental, social and economic aspects. Young children’s social play is viewed as a critical means to foster and enhance language, cognitive, social and emotional development. Social play theory has been predominately viewed from developmental perspectives. The classic study of Parten’s social play has been considered

Yaoying Xu

2010-01-01

283

Effective-Medium Models for Marine Gas Hydrates, Mallik Revisited  

NASA Astrophysics Data System (ADS)

Hertz-Mindlin type effective-medium dry-rock elastic models have been commonly used for more than three decades in rock physics analysis, and recently have been applied to assessment of marine gas hydrate resources. Comparisons of several effective-medium models with derivative well-log data from the Mackenzie River Valley, Northwest Territories, Canada (i.e. Mallik 2L-38 and 5L-38) were made several years ago as part of a marine gas hydrate joint industry project in the Gulf of Mexico. The matrix/grain supporting model (one of the five models compared) was clearly a better representation of the Mallik data than the other four models (2 cemented sand models; a pore-filling model; and an inclusion model). Even though the matrix/grain supporting model was clearly better, reservations were noted that the compressional velocity of the model was higher than the compressional velocity measured via the sonic logs, and that the shear velocities showed an even greater discrepancy. Over more than thirty years, variations of Hertz-Mindlin type effective medium models have evolved for unconsolidated sediments and here, we briefly review their development. In the past few years, the perfectly smooth grain version of the Hertz-Mindlin type effective-medium model has been favored over the infinitely rough grain version compared in the Gulf of Mexico study. We revisit the data from the Mallik wells to review assertions that effective-medium models with perfectly smooth grains are a better predictor than models with infinitely rough grains. We briefly review three Hertz-Mindlin type effective-medium models, and standardize nomenclature and notation. To calibrate the extended effective-medium model in gas hydrates, we use a well accepted framework for unconsolidated sediments through Hashin-Shtrikman bounds. We implement the previously discussed effective-medium models for saturated sediments with gas hydrates and compute theoretical curves of seismic velocities versus gas hydrate saturation to compare with well log data available from the Canadian gas hydrates research site. By directly comparing the infinitely rough and perfectly smooth grain versions of the Hertz-Mindlin type effective-medium model, we provide additional insight to the discrepancies noted in the Gulf of Mexico study.

Terry, D. A.; Knapp, C. C.; Knapp, J. H.

2011-12-01

284

Physical characteristics of subduction-type seismogenic zones revisited  

NASA Astrophysics Data System (ADS)

Based on both the Centennial earthquake catalog, the revised 1964-2007 EHB hypocenters and the 1976-2007 CMT Harvard catalog, we have extracted the hypocenters, nodal planes and seismic moments of worldwide subduction earthquakes for the period 1900-2007. For the period 1976-2007, we use the focal solutions provided by Harvard and the revised hypocenters from Engdahl et al. (1998). Older events are extracted from the Centennial catalogue (Engdahl and Villasenor, 2002) and they are used for the estimate of the cumulated seismic moment only. The criteria used to select the subduction earthquakes are similar to those used by Mc Caffrey (1994), i.e., we test if the focal mechanisms are consistent with 1/ shallow thrust events (positive slips, at least one nodal plane get dip < 45° and depth > 70 km), and, 2/ the plate interface local geometry and orientation (one nodal plane is oriented toward the volcanic arc, the azimut of this nodal plane is ± 45° with respect to the trench one, its dip is ± 20° with respect to the slab one and the epicenter is located seaward of the volcanic arc). Our study concerns segments of subduction zones that fit with estimated paleoruptures associated with major events (M > 8). We assume that the seismogenic zone coincides with the distribution of 5.5 < M < 7 subduction earthquakes. We then provide a map of the seismogenic zone for 36% of the oceanic subduction plates boundaries including dip, length, downdip and updip limits. The remnant 64% correspond to either weakly coupled oceanic subduction zones, slow subduction rates, or long recurrence period between earthquakes. We then revisit the statistical study done by Pacheco et al. (1993) and tested some empirical laws obtained for example by Kanamori (1986) in light of a more complete, more detailed, more accurate and more uniform description of the subduction interplate seismogenic zone. Since the subduction earthquakes result from stress accumulation along the interplate and that stress depends on plates kinematics, subduction zone geometry, thermal state and seismic coupling, we aim to isolate some correlations between parameters.

Heuret, A.; Lallemand, S.; Piromallo, C.; Funiciello, F.

2009-12-01

285

Curiosity and context revisited: crassulacean acid metabolism in the Anthropocene.  

PubMed

Having gained some understanding of the consequences of the CO(2)-concentrating mechanisms in crassulacean acid metabolism (CAM) that internalize the photosynthetic environment of the Cretaceous on a daily basis, it may be time to consider potential long-term effects of the planetary CO(2)-concentrating mechanism on growth and ecology of these plants in the Anthropocene. This paper emphasizes our limited understanding of the carbohydrate economy of CAM in relation to growth processes and briefly reviews recent studies of the diel cycles of growth in these plants. An inadvertent long-term, regional-scale experiment from the past is revisited in which an Opuntia monoculture grew to occupy >25 million hectares of farmland in central eastern Australia, producing a total biomass of about 1.5 billion tonnes in about 80 years. Although at the time it does not seem to have been recognized that this invasion involved CAM, a botanist from the University of Melbourne, Jean White-Haney emerges as a heroic pioneer in the control of the invader by poison and pioneered its biological control. The Opuntia population was expanding at 10-100 ha h(-1) when it was brought to a halt within a decade by the voracious appetite of Cactoblastis cactorum larvae. It is now known that the female parent moth of this predator detects CAM in O. stricta prior to oviposition by deploying the most sensitive CO(2) detector system yet found in the Lepidoptera. The O. stricta invasion is a dramatic demonstration of the capacity of CAM plants to attain and sustain high biomass; to sequester and retain atmospheric CO(2). In conclusion, experiments are reviewed that show stimulation of CO(2) assimilation, growth, and biomass of CAM plants by elevated atmospheric [CO(2)], and the proposition that these plants may have a role in atmospheric CO(2) sequestration is re-examined. This role may be compromised by predators such as Cactoblastis. However the moth CO(2) sensors are adapted to pre-industrial atmospheric [CO(2)] and FACE (free-air CO(2) enrichment) experiments show this exquisite system of biological control is also compromised by rising global [CO(2)] in the Anthropocene. PMID:18436545

Osmond, Barry; Neales, Tom; Stange, Gert

2008-04-23

286

Distant future of the Sun and Earth revisited  

NASA Astrophysics Data System (ADS)

We revisit the distant future of the Sun and the Solar system, based on stellar models computed with a thoroughly tested evolution code. For the solar giant stages, mass loss by the cool (but not dust-driven) wind is considered in detail. Using the new and well-calibrated mass-loss formula of Schröder & Cuntz, we find that the mass lost by the Sun as a red giant branch (RGB) giant (0.332Msolar, 7.59 Gyr from now) potentially gives planet Earth a significant orbital expansion, inversely proportional to the remaining solar mass. According to these solar evolution models, the closest encounter of planet Earth with the solar cool giant photosphere will occur during the tip-RGB phase. During this critical episode, for each time-step of the evolution model, we consider the loss of orbital angular momentum suffered by planet Earth from tidal interaction with the giant Sun, as well as dynamical drag in the lower chromosphere. As a result of this, we find that planet Earth will not be able to escape engulfment, despite the positive effect of solar mass loss. In order to survive the solar tip-RGB phase, any hypothetical planet would require a present-day minimum orbital radius of about 1.15 au. The latter result may help to estimate the chances of finding planets around white dwarfs. Furthermore, our solar evolution models with detailed mass-loss description predict that the resulting tip-AGB (asymptotic giant branch) giant will not reach its tip-RGB size. Compared to other solar evolution models, the main reason is the more significant amount of mass lost already in the RGB phase of the Sun. Hence, the tip-AGB luminosity will come short of driving a final, dust-driven superwind, and there will be no regular solar planetary nebula (PN). The tip-AGB is marked by a last thermal pulse, and the final mass loss of the giant may produce a circumstellar (CS) shell similar to, but rather smaller than, that of the peculiar PN IC 2149 with an estimated total CS shell mass of just a few hundredths of a solar mass.

Schröder, K.-P.; Connon Smith, Robert

2008-05-01

287

Revisiting Scaling Relations for Giant Radio Halos in Galaxy Clusters  

NASA Astrophysics Data System (ADS)

Many galaxy clusters host megaparsec-scale radio halos, generated by ultrarelativistic electrons in the magnetized intracluster medium. Correlations between the synchrotron power of radio halos and the thermal properties of the hosting clusters were established in the last decade, including the connection between the presence of a halo and cluster mergers. The X-ray luminosity and redshift-limited Extended GMRT Radio Halo Survey provides a rich and unique dataset for statistical studies of the halos. We uniformly analyze the radio and X-ray data for the GMRT cluster sample, and use the new Planck Sunyaev-Zel'dovich (SZ) catalog to revisit the correlations between the power of radio halos and the thermal properties of galaxy clusters. We find that the radio power at 1.4 GHz scales with the cluster X-ray (0.1-2.4 keV) luminosity computed within R 500 as P_{1.4} \\sim L^{2.1+/- 0.2}_{500}. Our bigger and more homogenous sample confirms that the X-ray luminous (L 500 > 5 × 1044 erg s–1) clusters branch into two populations—radio halos lie on the correlation, while clusters without radio halos have their radio upper limits well below that correlation. This bimodality remains if we excise cool cores from the X-ray luminosities. We also find that P 1.4 scales with the cluster integrated SZ signal within R 500, measured by Planck, as P_{1.4}\\sim Y^{2.05+/- 0.28}_{500}, in line with previous findings. However, contrary to previous studies that were limited by incompleteness and small sample size, we find that "SZ-luminous" Y 500 > 6 × 10–5 Mpc2 clusters show a bimodal behavior for the presence of radio halos, similar to that in the radio-X-ray diagram. Bimodality of both correlations can be traced to clusters dynamics, with radio halos found exclusively in merging clusters. These results confirm the key role of mergers for the origin of giant radio halos, suggesting that they trigger the relativistic particle acceleration.

Cassano, R.; Ettori, S.; Brunetti, G.; Giacintucci, S.; Pratt, G. W.; Venturi, T.; Kale, R.; Dolag, K.; Markevitch, M.

2013-11-01

288

Revisiting the physical characterisitics of the subduction interplate seismogenic zones  

NASA Astrophysics Data System (ADS)

Based on the Centennial earthquake catalog, the revised 1964-2007 EHB hypocenters catalog and the 1976-2007 CMT Harvard catalog, we have extracted the hypocenters, nodal planes and seismic moments of worldwide subduction earthquakes for the 1900-2007 period. For the 1976-2007 period, we combine the focal solutions provided by Harvard and the revised hypocenters from Engdahl et al. (1998). Older events are extracted from the Centennial catalogue (Engdahl and Villasenor, 2002) and they are used to estimate the cumulated seismic moment only. The selection criteria for the subduction earthquakes are similar to those used by Mc Caffrey (1994), i.e., we test if the focal mechanisms are consistent with 1/ shallow thrust events (depth > 70 km, positive slips, and at least one nodal plane gets dip < 45°), and, 2/ the plate interface local geometry and orientation (one nodal plane is oriented toward the volcanic arc, the azimuth of this nodal plane ranges between ± 45° with respect to the trench one, its dip ranges between ± 20° with respect to the slab one and the epicentre is located seaward of the volcanic arc). Our study concerns segments of subduction zones that fit with estimated paleoruptures associated with major events (M > 8). We assume that the seismogenic zone coincides with the distribution of 5.5 < M < 7 subduction earthquakes. We provide a map of the interplate seismogenic zones for 80% of the trench systems including dip, length, downdip and updip limits, we revisit the statistical study done by Pacheco et al. (1993) and test some empirical laws obtained for example by Ruff and Kanamori (1980) in light of a more complete, detailed, accurate and uniform description of the subduction interplate seismogenic zone. Since subduction earthquakes result from stress accumulation along the interplate and stress depends on plates kinematics, subduction zone geometry, thermal state and seismic coupling, we aim to isolate some correlations between parameters. The statistical analysis reveals that: 1- vs, the subduction velocity is the first order controlling parameter of seismogenic zone variability, both in term of geometry and seismic behaviour; 2- steep dip, large vertical extent and narrow horizontal extent of the seismogenic zone are associated to fast subductions, and cold slabs, the opposite holding for slow subductions and warm slabs; the seismogenic zone usually ends in the fore-arc mantle rather than at the upper plate Moho depth; 3- seismic rate (?) variability is coherent with the geometry of the seismogenic zone: ? increases with the dip and with the vertical extent of the seismogenic zone, and it fits with vs and with the subducting plate thermal state; 4- mega-events occurrence determines the level of seismic energy released along the subduction interface, whatever ? is; 5- to some extent, the potential size of earthquakes fits with vs and with the seismogenic zone geometry, but second order controlling parameters are more difficult to detect; 6- the plate coupling, measured through Upper Plate Strain, is one possible second order parameter: mega-events are preferentially associated to neutral subductions, i.e. moderate compressive stresses along the plate interface; high plate coupling (compressive UPS) is thought to inhibit mega-events genesis by enhancing the locking of the plate interface and preventing the rupture to extend laterally. This research was supported as part of the Eurohorcs/ESF — European Young Investigators Awards Scheme (resp. F.F.), by funds from the National Research Council of Italy and other National Funding Agencies participating in the 3rd Memorandum of Understanding, as well as from the EC Sixth Framework Programme.

Heuret, Arnauld; Lallemand, Serge; Funiciello, Francesca; Piromallo, Claudia

2010-05-01

289

Structuralism’s relevance in a post-structural era: Re-visiting research on multicultural curricular studies  

Microsoft Academic Search

At the current historical juncture in which differences and inequalities are surfacing greater than ever in the world, societies, and schools, the main goal of this essay is to revisit the aspects of structuralism that can potentially contribute productively to understanding the invisible structures and forces that everyone carries (mostly unknowingly) with them at all times and in all places

Jenna Min Shim

2011-01-01

290

The fit between capabilities and priorities and its impact on performance improvement: revisiting and extending the theory of production competence  

Microsoft Academic Search

This paper revisits and extends the theory of production competence, which has received wide attention in the operations and production management literature. As such, considering the aspects of quality, delivery, flexibility, and cost, we develop two novel measures that assess the concept of production competence, which is conceptualised as the fit between production and operations management (POM) capabilities and production

Tobias Schoenherr; Ram Narasimhan

2011-01-01

291

The fit between capabilities and priorities and its impact on performance improvement: revisiting and extending the theory of production competence  

Microsoft Academic Search

This paper revisits and extends the theory of production competence, which has received wide attention in the operations and production management literature. As such, considering the aspects of quality, delivery, flexibility, and cost, we develop two novel measures that assess the concept of production competence, which is conceptualised as the fit between production and operations management (POM) capabilities and production

Tobias Schoenherr; Ram Narasimhan

2012-01-01

292

Revisiting the melting temperature of NpO2 and the challenges associated with high temperature actinide compound measurements  

Microsoft Academic Search

This work revisits the melting behaviour of neptunium dioxide, an actinide compound which can be produced in the nuclear fuel during operation, and which has an important impact on the nuclear fuel and waste radioactivity especially on the very long term. The present experimental approach employs remote laser heating under controlled atmosphere and fast pyrometry. This technique circumvents problems encountered

R. Böhler; M. J. Welland; F. De Bruycker; K. Boboridis; A. Janssen; R. Eloirdi; R. J. M. Konings; D. Manara

2012-01-01

293

Mirror, mirror, on the wall, who in this land is fairest of all? Revisiting the extended concentration index  

Microsoft Academic Search

This paper explores three alternative indices for measuring health inequalities in a way that takes into account attitudes towards inequality. Firstly, we revisit the extended concentration index which has been proposed to generalise the value judgements implicit in the standard concentration index. We then examine two alternative measures which have desirable mirror properties. One of these indices applies symmetric weights

Erreygers G; Clarke Ph; Van Ourti T

2010-01-01

294

Revisiting the early childhood-health dyad: Health promotion in early childhood settings - Implications for policy and practice  

Microsoft Academic Search

Abstract This article stresses the need to revisit the early childhood-health partnership in relation to childcare services. The author reviews contrasting notions of sickness and health and shows how social determinants have become ,significant predictors of long-term health and wellbeing for children and families. Building on this, the health promotion movement of WHO has stressed the importance of partnerships and

Jacqueline Hayden

295

Today's Teens, Their Problems, and Their Literature: Revisiting G. Robert Carlsen's "Books and the Teenage Reader" Thirty Years Later.  

ERIC Educational Resources Information Center

Revisits G. Robert Carlsen's call for the use of young adult literature in the classroom by looking specifically at the emotional and reading needs of older adolescents, those in the upper grades. Discusses problems associated with adolescence in the late twentieth century and lists recommended young adult books that touch on those issues. (TB)

Carroll, Pamela Sissi

1997-01-01

296

Revisiting Du Bois: The Relationship Between African American Double Consciousness and Beliefs About Racial and National Group Experiences  

Microsoft Academic Search

This study revisits Du Bois’s concept of double consciousness by examining the relationship between racial and mainstream acculturation and African Americans’ beliefs about their racial and national groups. Surveys completed by 100 prospective Black jurors at a municipal courthouse approximately 6 months after 9\\/11 revealed that they perceived their racial group as more unjustly treated and more helpless than their

Mikhail Lyubansky; Roy J. Eidelson

2005-01-01

297

Revisiting Risk in the 21st Century. Forum Focus. Volume 3, Issue 1, January-February 2005  

ERIC Educational Resources Information Center

|Over the past year, dozens of articles have been published about excessive youth borrowing and spending (leading to high amounts of debt), new reactions to negative body image (such as plastic surgery), as well as more familiar risks like premarital sex and smoking. In Forum Focus: Revisiting Risk in the 21st Century, we explore these challenges…

Forum for Youth Investment, 2005

2005-01-01

298

Running in the Shadows: Revisiting In the Shadows of Romance: Romantic Tragic Drama in Germany, England, and France  

Microsoft Academic Search

This essay reflects on In the Shadows of Romance: Romantic Tragic Drama in Germany, England, and France (1987), revisiting its genesis, aims, and accomplishments. The book appeared at a time when little attention was paid to Romantic drama, and it thus focused widely on drama in three national traditions. While Romanticists have subsequently made great strides in recovering, interpreting, and

Jeffrey N. Cox

2012-01-01

299

Top Ten Mistakes of Shopping Cart Design Revisited: A Survey of 500 Top E-Commerce Websites  

Microsoft Academic Search

Summary: A list of common mistakes with e-commerce shopping cart design were identified in a previous issue of Usability News. This article revisits that list and reviews how 500 of the top Internet retail sites of today implemented their shopping cart design.

Barbara S. Chaparro; Shivashankar Naidu

300

Revisiting Risk in the 21st Century. Forum Focus. Volume 3, Issue 1, January-February 2005  

ERIC Educational Resources Information Center

Over the past year, dozens of articles have been published about excessive youth borrowing and spending (leading to high amounts of debt), new reactions to negative body image (such as plastic surgery), as well as more familiar risks like premarital sex and smoking. In Forum Focus: Revisiting Risk in the 21st Century, we explore these challenges…

Forum for Youth Investment, 2005

2005-01-01

301

Borobudur revisited: Soy consumption may be associated with better recall in younger, but not in older, rural Indonesian elderly  

Microsoft Academic Search

Previous reports have suggested that high frequent tofu consumption is associated with worse cognitive function in East Asian elderly. Some studies also found an increased risk of dementia with high tofu consumption in those older than 65years of age. Tofu and other soy products, such as tempeh, contain high levels of plant estrogens or isoflavones. This study revisited a rural

Eef Hogervorst; Fidiansjah Mursjid; Dewi Priandini; Henry Setyawan; Raden Irawati Ismael; Stephan Bandelow; Tri Budi Rahardjo

2011-01-01

302

Ortho/Para Ratio of H2O+ Toward Sagittarius B2(M) Revisited  

NASA Astrophysics Data System (ADS)

The HIFI instrument aboard the Herschel satellite has allowed the observation and characterization of light hydrides, the building blocks of interstellar chemistry. In this article, we revisit the ortho/para ratio for H2O+ toward the Sgr B2(M) cloud core. The line of sight toward this star forming region passes through several spiral arms and the gas in the Bar potential in the inner Galaxy. In contrast to earlier findings, which used fewer lines to constrain the ratio, we find a ratio of 3, which is uniformly consistent with high-temperature formation of the species. In view of the reactivity of this ion, this matches the expectations.

Schilke, Peter; Lis, Dariusz C.; Bergin, Edwin A.; Higgins, Ronan; Comito, Claudia

2013-10-01

303

Wittig Reaction: The Synthesis of trans-9-(2-Phenylethenyl)anthracene Revisited  

NASA Astrophysics Data System (ADS)

The revisit to this experimental procedure resulted in making a good undergraduate laboratory procedure even better. In this Wittig reaction, readily available starting materials are used; only the trans isomer is produced; the clear and characteristic 1H NMR spectrum of the product is ideal for a lesson in coupling constants to determine stereochemistry; and the product can be readily used in additional brilliant chemiluminescence laboratory experiments. The problematic step of generating tough emulsions during extractions with halogenated solvents has been eliminated by using N,N-dimethylformamide as the reaction solvent and readily precipitating the product from the reaction mixture using 1-propanol and water.

Jaworek, Christine; Iacobucci, Sarah

2002-01-01

304

2-Hy-droxy-3-meth-oxy-benzaldehyde (o-vanillin) revisited  

PubMed Central

The structure of ortho-vanillin, C8H8O3, has been revisited with modern methods and at low temperature (100?K). The previous structure [Iwasaki et al. (1976 ?). Acta Cryst. B32, 1264–1266] is confirmed, but geometric precision is improved by an order of magnitude. The C atom of the meth­oxy group lies close to the benzene ring plane, which is the most common geometry for –OMe groups lying ortho to –OH groups on an aromatic ring. The crystal structure displays one intra­molecular O—H?O and three weak inter­molecular C—H?O hydrogen bonds.

Shin, David; Muller, Peter

2012-01-01

305

A parable of oil and water: Revisiting Prince William Sound, four years after  

SciTech Connect

On Good Friday, March 24, 1989, the Exxon oil tanker Valdez foundered on Bligh Reef, spilling 11 million gallons of crude oil into Alaska`s Prince William Sound. To Alaskans, especially fishing people, this was a shocking but not entirely unanticipated event, as there had been several near misses in the twelve years since the opening of oil shipping from Valdez, Alaska. This article revisits Prince William sound to evaluate both the lingering environmental effects and the socio-economic effects of the spill and the huge monetary settlement from the spills.

Keeble, J.

1993-12-31

306

Investigating Predictors of Visiting, Using, and Revisiting an Online Health-Communication Program: A Longitudinal Study  

PubMed Central

Background Online health communication has the potential to reach large audiences, with the additional advantages that it can be operational at all times and that the costs per visitor are low. Furthermore, research shows that Internet-delivered interventions can be effective in changing health behaviors. However, exposure to Internet-delivered health-communication programs is generally low. Research investigating predictors of exposure is needed to be able to effectively disseminate online interventions. Objective In the present study, the authors used a longitudinal design with the aim of identifying demographic, psychological, and behavioral predictors of visiting, using, and revisiting an online program promoting physical activity in the general population. Methods A webpage was created providing the public with information about health and healthy behavior. The website included a “physical activity check,” which consisted of a physical activity computer-tailoring expert system where visitors could check whether their physical activity levels were in line with recommendations. Visitors who consented to participate in the present study (n = 489) filled in a questionnaire that assessed demographics, mode of recruitment, current physical activity levels, and health motivation. Immediately after, participants received tailored feedback concerning their current physical activity levels and completed a questionnaire assessing affective and cognitive user experience, attitude toward being sufficiently physically active, and intention to be sufficiently physically active. Three months later, participants received an email inviting them once more to check whether their physical activity level had changed. Results Analyses of visiting showed that more women (67.5%) than men (32.5%) visited the program. With regard to continued use, native Dutch participants (odds ratio [OR] = 2.81, 95% confidence interval [CI] = 1.16-6.81, P = .02) and participants with a strong motivation to be healthy (OR = 1.46, CI = 1.03-2.07, P = .03) were most likely to continue usage of the program. With regard to revisiting, older participants (OR = 1.04, CI = 1.01-1.06, P = .01) and highly educated participants (OR = 4.69, CI = 1.44-15.22, P = .01) were more likely to revisit the program after three months. In addition, positive affective user experience predicted revisiting (OR = 1.64, CI = 1.12-2.39, P = .01). Conclusions The results suggest that online interventions could specifically target men, young people, immigrant groups, people with a low education, and people with a weak health motivation to increase exposure to these interventions. Furthermore, eliciting positive feelings in visitors may contribute to higher usage rates.

Crutzen, Rik; De Vries, Hein

2010-01-01

307

Gauge-covariant canonical formalism revisited with application to the proton spin decomposition  

NASA Astrophysics Data System (ADS)

We revisit the gauge-covariant canonical formalism by separating explicitly physical and gauge degrees of freedom. We show in particular that the gauge-invariant linear and angular momentum operators proposed by Chen et al. can consistently be derived from the standard procedure based on Noether’s theorem. Finally, we demonstrate that this approach is essentially equivalent to the gauge-invariant canonical formalism based on the concept of Dirac variables. Because of many similarities with the background field method, the formalism developed here should also be relevant to general relativity and any metric theories.

Lorcé, Cédric

2013-08-01

308

Hall-Petch Law Revisited in Terms of Collective Dislocation Dynamics  

SciTech Connect

The Hall-Petch (HP) law, that accounts for the effect of grain size on the plastic yield stress of polycrystals, is revisited in terms of the collective motion of interacting dislocations. Sudden relaxation of incompatibility stresses in a grain triggers aftershocks in the neighboring ones. The HP law results from a scaling argument based on the conservation of the elastic energy during such transfers. The Hall-Petch law breakdown for nanometric sized grains is shown to stem from the loss of such a collective behavior as grains start deforming by successive motion of individual dislocations.

Louchet, Francois; Weiss, Jerome; Richeton, Thiebaud [Laboratoire de Glaciologie et de Geophysique de l'Environnement, Universite Joseph Fourier/CNRS, BP96 - 38402 Saint Martin d'Heres (France)

2006-08-18

309

MWIR persistent surveillance performance for human and vehicle backtracking as a function of ground sample distance and revisit rate  

NASA Astrophysics Data System (ADS)

Real MWIR Persistent Surveillance (PS) data was taken with a single human walking from a known point to different tents in the PS sensor field of view. The spatial resolution (ground sample distance) and revisit rate was varied from 0.5 to 2 meters and 1/8th to 4 Hz, respectively. A perception experiment was conducted where the observer was tasked to track the human to the terminal (end of route) tent. The probability of track is provided as a function of ground sample distance and revisit rate. These results can help determine PS design requirements for tracking and back-tracking humans on the ground. This paper begins with a summary of two previous simulation experiments: one for human tracking and one for vehicle tracking.

Driggers, R.; Aghera, S.; Richardson, P.; Miller, B.; Doe, J.; Robinson, A.; Krapels, K.; Murrill, S.

2008-05-01

310

Understanding and Revisiting Properties of EuTiO3 Bulk Material and Films from First Principles  

NASA Astrophysics Data System (ADS)

Ab initio computations are performed to investigate properties of bulk material and epitaxial films made of EuTiO3 (ETO). A whole family of nanoscale twinned phases, that present complex oxygen octahedra tilting (OOT) and unusual antiferroelectricity, is found to be degenerate in energy with simpler phases (all possessing typical OOT) in bulk ETO. Such degeneracy provides a successful explanation of recently observed anomalous phenomena. The calculations also lead to revisiting the (rich) phase diagram of ETO films.

Yang, Yurong; Ren, Wei; Wang, Dawei; Bellaiche, L.

2012-12-01

311

Decision-making in the physician–patient encounter: revisiting the shared treatment decision-making model  

Microsoft Academic Search

In this paper we revisit and add elements to our earlier conceptual framework on shared treatment decision-making within the context of different decision-making approaches in the medical encounter (Charles, C., Gafni, A., Whelan, T., 1997. Shared decision-making in the medical encounter: what does it mean? (or, it takes at least two to tango). Social Science & Medicine 44, 681–692.). This

Cathy Charles; Amiram Gafni; Tim Whelan

1999-01-01

312

Wild mouse lemurs revisit artificial feeding platforms: implications for field experiments on sensory and cognitive abilities in small primates.  

PubMed

Dealing effectively with space to find important resources in a natural environment is a fundamental ability necessary for survival. Evidence has already been provided that wild gray mouse lemurs revisit stationary feeding sites regularly. In this study, we explore to what extent two sympatric mouse lemur species, Microcebus murinus and M. ravelobensis, revisited artificial feeding sites during a period of food scarcity. As the tested populations are marked with individual transponders, we built up artificial feeding platforms equipped with a transponder reader at nine different locations where mouse lemurs had been previously caught. We baited them with a liquid reward and recorded the visitors' ID, the time and frequency of their visits, as well as all encounters that occurred on the platforms. Only mouse lemurs visited platforms and a total of sixteen individuals across both species were identified. Mouse lemurs visited a platform with a frequency of 2.02 (+/-0.95, range: 1-3.4) times in a night and they revisited it on several consecutive nights following their first visit (percentage of revisits 90.6%+/-11.7, range: 73.3-100%). First visits on a platform occurred on average 44 min (+/-35; range: 13-131) after sunset. We identified encounters between mouse lemurs on platforms: all of them were agonistic and within a species. Within a dyad, chasers were significantly heavier than chasees (N=7 dyads). Our design of platform experiments offers the advantage of observing wild individually known small primates in their natural environment and of setting up controlled experiments to gain insight into their sensory and cognitive abilities. PMID:18561263

Joly, Marine; Scheumann, Marina; Zimmermann, Elke

2008-09-01

313

Aztec arithmetic revisited: land-area algorithms and Acolhua congruence arithmetic.  

PubMed

Acolhua-Aztec land records depicting areas and side dimensions of agricultural fields provide insight into Aztec arithmetic. Hypothesizing that recorded areas resulted from indigenous calculation, in a study of sample quadrilateral fields we found that 60% of the area values could be reproduced exactly by computation. In remaining cases, discrepancies between computed and recorded areas were consistently small, suggesting use of an unknown indigenous arithmetic. In revisiting the research, we discovered evidence for the use of congruence principles, based on proportions between the standard linear Acolhua measure and their units of shorter length. This procedure substitutes for computation with fractions and is labeled "Acolhua congruence arithmetic." The findings also clarify variance between Acolhua and Tenochca linear units, long an issue in understanding Aztec metrology. PMID:18388287

Williams, Barbara J; Jorge y Jorge, María del Carmen

2008-04-01

314

Evidence for Two Distinct Stellar Initial Mass Functions: Revisiting the Effects of Cluster Dynamical Evolution  

NASA Astrophysics Data System (ADS)

We measure the velocity dispersions of six galactic globular clusters using spatially integrated spectra, to test for the effects of internal dynamical evolution in the stellar mass-to-light ratios, Upsilon*, of star clusters. In particular, we revisit whether the low values of Upsilon* that we found in our previous study, from which we concluded that there are at least two population of stellar clusters with distinct stellar initial mass functions, are artificially depressed by relaxation driven mass loss. The combination of our previous sample of five old clusters and these six now provide an order of magnitude range in cluster mass with which to explore this issue. We find no relationship between cluster mass, or relaxation time, and Upsilon*. Because relaxation is mass dependent, we conclude that the values of Upsilon* for these clusters are not strongly affected by dynamical effects, and so confirm the presence of the population of clusters with low Upsilon*.

Zaritsky, Dennis; Colucci, Janet E.; Pessev, Peter M.; Bernstein, Rebecca A.; Chandar, Rupali

2013-06-01

315

The impact of minimum legal drinking age laws on alcohol consumption, smoking, and marijuana use revisited.  

PubMed

In volume 30, issue 4 of this journal, we used data from the National Longitudinal Study of Youth, 1997 cohort (NLSY97) to estimate the impact of the minimum legal drinking age (MLDA) laws on alcohol consumption, smoking, and marijuana use among young adults. In our analysis, we used a restricted sample of young adults and considered only those who have consumed alcohol, smoked cigarettes, or used marijuana at least once since the date of their last interview. In this paper, we revisit our original study using the full sample. We show that our results for alcohol consumption in the full sample are similar to those from the restricted sample. However, the effect of the MLDA on smoking and marijuana use is smaller and often statistically insignificant. PMID:23092933

Yörük, Bar?? K; Yörük, Ceren Ertan

2012-10-03

316

GAMMA-RAY BURST PROMPT EMISSION: JITTER RADIATION IN STOCHASTIC MAGNETIC FIELD REVISITED  

SciTech Connect

We revisit the radiation mechanism of relativistic electrons in the stochastic magnetic field and apply it to the high-energy emissions of gamma-ray bursts (GRBs). We confirm that jitter radiation is a possible explanation for GRB prompt emission in the condition of a large electron deflection angle. In the turbulent scenario, the radiative spectral property of GRB prompt emission is decided by the kinetic energy spectrum of turbulence. The intensity of the random and small-scale magnetic field is determined by the viscous scale of the turbulent eddy. The microphysical parameters {epsilon}{sub e} and {epsilon}{sub B} can be obtained. The acceleration and cooling timescales are estimated as well. Due to particle acceleration in magnetized filamentary turbulence, the maximum energy released from the relativistic electrons can reach a value of about 10{sup 14} eV. The GeV GRBs are possible sources of high-energy cosmic-ray.

Mao, Jirong [International Center for Astrophysics, Korea Astronomy and Space Science Institute, 776, Daedeokdae-ro, Yuseong-gu, Daejeon 305-348 (Korea, Republic of); Wang Jiancheng, E-mail: jirong.mao@brera.inaf.it [Yunnan Observatory, Chinese Academy of Sciences, Kunming, Yunnan Province 650011 (China)

2011-04-10

317

Antiresonant reflecting optical waveguide microstructured fibers revisited: a new analysis based on leaky mode coupling.  

PubMed

Using two different modal methods, the multipole method and the more recent fast Fourier factorization method, we exhibit and explain a core mode transition induced by avoided crossing between a core localized leaky mode and an high-index cylinder leaky mode in anti-resonant reflecting optical waveguide microstructured optical fibers (ARROW MOFs). Due to its wavelength selectivity and to the leaky nature of the involved modes, this transition doesn't seem to have already been described in detail and analyzed as done in this work in spite of several already published studies on core mode dispersion properties. The main properties of this transition are also described. We also revisite the already mentionned cut-off phenomena limiting the transmission band in ARROW MOFs in terms of mode coupling between the core mode and one or several high- index cylinder modes. PMID:19516737

Renversez, Gilles; Boyer, Philippe; Sagrini, Angelo

2006-06-12

318

Revisiting the {P} {T}-symmetric trimer: bifurcations, ghost states and associated dynamics  

NASA Astrophysics Data System (ADS)

In this paper, we revisit one of the prototypical {P} {T}-symmetric oligomers, namely the trimer. We find all the relevant branches of ‘regular’ solutions and analyze the bifurcations and instabilities thereof. Our work generalizes the formulation that was recently proposed in the case of dimers for the so-called ‘ghost states’ of trimers, which we also identify and connect to symmetry-breaking bifurcations from the regular states. We also examine the dynamics of unstable trimers, as well as those of the ghost states in the parametric regime where the latter are found to exist. Finally, we present the current state-of-the-art for optical experiments in {P} {T}-symmetric trimers, as well as experimental results in a gain-loss-gain three channel waveguide structure.

Li, K.; Kevrekidis, P. G.; Frantzeskakis, D. J.; Rüter, C. E.; Kip, D.

2013-09-01

319

Gamma-ray Burst Prompt Emission: Jitter Radiation in Stochastic Magnetic Field Revisited  

NASA Astrophysics Data System (ADS)

We revisit the radiation mechanism of relativistic electrons in the stochastic magnetic field and apply it to the high-energy emissions of gamma-ray bursts (GRBs). We confirm that jitter radiation is a possible explanation for GRB prompt emission in the condition of a large electron deflection angle. In the turbulent scenario, the radiative spectral property of GRB prompt emission is decided by the kinetic energy spectrum of turbulence. The intensity of the random and small-scale magnetic field is determined by the viscous scale of the turbulent eddy. The microphysical parameters epsilon e and epsilon B can be obtained. The acceleration and cooling timescales are estimated as well. Due to particle acceleration in magnetized filamentary turbulence, the maximum energy released from the relativistic electrons can reach a value of about 1014 eV. The GeV GRBs are possible sources of high-energy cosmic-ray.

Mao, Jirong; Wang, Jiancheng

2011-04-01

320

Particle production at high energy and large transverse momentum: 'The hybrid formalism' revisited  

SciTech Connect

We revisit the 'hybrid formalism' for particle production used recently to study saturation effects in single hadron multiplicities at forward rapidities at RHIC and LHC. We point out that at leading twist there is an extra contribution to the formulae used so far, which corresponds to particle production via inelastic scattering of the projectile partons on the target fields. This contribution is expected to be small due to kinematics at very forward rapidities/very high transverse momenta, but should be significant at high momenta and very high energies. This contribution is expected to be most affected by saturation effects, and is therefore an interesting object of study in the context of possible onset of saturation at high energies.

Altinoluk, Tolga; Kovner, Alex [Physics Department, University of Connecticut, 2152 Hillside Road, Storrs, Connecticut 06269-3046 (United States)

2011-05-15

321

Revisiting scope of practice facilitators and barriers for primary care nurse practitioners: a qualitative investigation.  

PubMed

Revisiting scope of practice (SOP) policies for nurse practitioners (NPs) is necessary in the evolving primary care environment with goals to provide timely access, improve quality, and contain cost. This study utilized qualitative descriptive design to investigate NP roles and responsibilities as primary care providers (PCPs) in Massachusetts and their perceptions about barriers and facilitators to their SOP. Through purposive sampling, 23 NPs were recruited and they participated in group and individual interviews in spring 2011.The interviews were audio recorded and transcribed. Data were analyzed using Atlas.ti 6.0 software, and content analysis was applied. In addition to NP roles and responsibilities, three themes affecting NP SOP were: regulatory environment; comprehension of NP role; and work environment. NPs take on similar responsibilities as physicians to deliver primary care services; however, the regulatory environment and billing practices, lack of comprehension of the NP role, and challenging work environments limit successful NP practice. PMID:23528433

Poghosyan, Lusine; Nannini, Angela; Smaldone, Arlene; Clarke, Sean; O'Rourke, Nancy C; Rosato, Barbara G; Berkowitz, Bobbie

2013-03-25

322

Productions of heavy charged leptons via gluon fusion at the LHC: A revisit  

SciTech Connect

Heavy charged lepton productions via gluon fusion at the LHC are revisited. Full loop calculations are adopted with an updated parton distribution function and electroweak data. Including contribution from new generation quarks in the loop, pair production of the sequential heavy lepton via gluon fusion at the LHC dominates over that via the Drell-Yan mechanism in some heavy lepton mass range. Exotic lepton single production of vectorlike lepton extended models is also calculated. In the later case, the gluon fusion mechanism via the Higgs exchange is emphasized. Our numerical results for both pair and single production of heavy leptons are smaller than previous studies especially for a large heavy lepton mass as a result of full loop calculation and due to the mixing angles.

Liu Chun; Yang Shuo [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China)

2010-05-01

323

Network and system diagrams revisited: Satisfying CEA requirements for causality analysis  

SciTech Connect

Published guidelines for Cumulative Effects Assessment (CEA) have called for the identification of cause-and-effect relationships, or causality, challenging researchers to identify methods that can possibly meet CEA's specific requirements. Together with an outline of these requirements from CEA key literature, the various definitions of cumulative effects point to the direction of a method for causality analysis that is visually-oriented and qualitative. This article consequently revisits network and system diagrams, resolves their reported shortcomings, and extends their capabilities with causal loop diagramming methodology. The application of the resulting composite causality analysis method to three Environmental Impact Assessment (EIA) case studies appears to satisfy the specific requirements of CEA regarding causality. Three 'moments' are envisaged for the use of the proposed method: during the scoping stage, during the assessment process, and during the stakeholder participation process.

Perdicoulis, Anastassios [University of Tras-os-Montes e Alto Douro, 5001-801 Vila Real (Portugal); University of Tras-os-Montes e Alto Douro, 5001-801 Vila Real (Portugal); Piper, Jake [Oxford Institute for Sustainable Development, Oxford Brookes University, Headington Campus, Gipsy, Lane, Oxford OX3 0BP (United Kingdom)

2008-10-15

324

Amish revisited: next-generation sequencing studies of psychiatric disorders among the Plain people.  

PubMed

The rapid development of next-generation sequencing (NGS) technology has led to renewed interest in the potential contribution of rarer forms of genetic variation to complex non-mendelian phenotypes such as psychiatric illnesses. Although challenging, family-based studies offer some advantages, especially in communities with large families and a limited number of founders. Here we revisit family-based studies of mental illnesses in traditional Amish and Mennonite communities--known collectively as the Plain people. We discuss the new opportunities for NGS in these populations, with particular emphasis on investigating psychiatric disorders. We also address some of the challenges facing NGS-based studies of complex phenotypes in founder populations. PMID:23422049

Hou, Liping; Faraci, Gloria; Chen, David T W; Kassem, Layla; Schulze, Thomas G; Shugart, Yin Yao; McMahon, Francis J

2013-02-17

325

Nice to kin and nasty to non-kin: revisiting Hamilton's early insights on eusociality.  

PubMed

When helping behaviour is costly, Hamiltonian logic implies that animals need to direct helpful acts towards kin, so that indirect fitness benefits justify the costs. We revisit inferences about nepotism and aggression in Hamilton's 1964 paper to argue that he overestimated the general significance of nepotism, but that other issues that he raised continue to suggest novel research agendas today. We now know that nepotism in eusocial insects is rare, because variation in genetic recognition cues is insufficient. A lower proportion of individuals breeding and larger clutch sizes selecting for a more uniform colony odour may explain this. Irreversible worker sterility can induce both the fiercest possible aggression and the highest likelihood of helping random distant kin, but these Hamiltonian contentions still await large-scale testing in social animals. PMID:24132094

Boomsma, Jacobus J; d'Ettorre, Patrizia

2013-10-16

326

Resonance-assisted hydrogen bonds revisited. Resonance stabilization vs. charge delocalization.  

PubMed

The origins of stabilization in the short strong hydrogen bonds commonly referred to as "resonance-assisted" (RAHB) have been revisited using the modern valence-bond theory, the hybrid variational-perturbational interaction energy decomposition scheme and atoms in molecules (AIM) analysis. Dimers of carboxylic acids and amides have been chosen as the model structures for intermolecular RAHBs, while for the intramolecular case malondialdehyde and its substituted derivatives have been selected. The estimated (negligible) resonance stabilization energies and relative magnitudes of interaction energy components indicate that the origin of stabilization in the studied complexes is charge-delocalization. Although in the case of intramolecular RAHBs the resonance effects are much more pronounced, still they are a relatively minor contribution to the total stabilization energy. In fact, the estimated resonance stabilization energies diminish with an increasing strength of the hydrogen bond (as indicated by AIM and structural descriptors). PMID:23322083

Góra, Robert W; Maj, Micha?; Grabowski, S?awomir J

2013-01-15

327

Cancer stem cells, endothelial progenitors, and mesenchymal stem cells: "seed and soil" theory revisited.  

PubMed

Isolation of putative cancer stem cells (CSCs) in various tumors has generated much excitement among researchers who consider these cells the potential "culprits" behind resistance to conventional therapy. Both cancer and cardiovascular disease are believed to be stem cell disorders involving circulating endothelial progenitors (CEPs) and mesenchymal stem cells (MSCs). CD133 and CD44, markers of CSCs in many tumors, also enrich CEPs and MSCs, respectively. We propose an integrated tumorigenesis model that involves all three interdependent stem cell (CSC, CEP, MSC) compartments by revisiting the "seed and soil" model. Developing therapeutics that can effectively target CSCs and spare normal cardiovascular tissue will remain a challenge. Preliminary laboratory and clinical data on monitoring and targeting colon CSCs, using such a modeling system, are discussed. PMID:19259284

Lin, Edward H; Jiang, Yixing; Deng, Yanhong; Lapsiwala, Ritu; Lin, Tongyu; Blau, C Anthony

2008-07-01

328

Re-visit local coupling correction in the interaction regions of RHIC  

SciTech Connect

In this article we will re-visit the local coupling correction in the interaction regions (IRs) of the Relativistic Heavy Ion Collider (RHIC). We will review the measurement data of triplet quadrupole rolls, the local coupling correction strengths in the RHIC control system, and the methods for the local coupling correction with local skew quadrupole correctors. Based on the in-turnnel measurement data of triplet roll errors in 2011, we will analytically calculate and simulate IR-bump method to find out the local skew correction strengths and compare them at store and at injection with the Blue and Yellow ring lattices in the 2011 polarized proton (p-p) and Au-Au runs. The vertical dispersion from the triplet roll errors, local and global coupling correction skew quadrupoles, and the vertical dipole correctors are calculated and discussed.

Luo, Y.; Fischer, W.; Liu, C.; Marusic, A.; Minty, M.; Ptitsyn, V.; Schoefer, V.; Tepikian, S.; Trbojevic, D.; Zimmer, C.

2011-11-01

329

Genomic exploration of the hemiascomycetous yeasts: 4. The genome of Saccharomyces cerevisiae revisited.  

PubMed

Since its completion more than 4 years ago, the sequence of Saccharomyces cerevisiae has been extensively used and studied. The original sequence has received a few corrections, and the identification of genes has been completed, thanks in particular to transcriptome analyses and to specialized studies on introns, tRNA genes, transposons or multigene families. In order to undertake the extensive comparative sequence analysis of this program, we have entirely revisited the S. cerevisiae sequence using the same criteria for all 16 chromosomes and taking into account publicly available annotations for genes and elements that cannot be predicted. Comparison with the other yeast species of this program indicates the existence of 50 novel genes in segments previously considered as 'intergenic' and suggests extensions for 26 of the previously annotated genes. PMID:11152879

Blandin, G; Durrens, P; Tekaia, F; Aigle, M; Bolotin-Fukuhara, M; Bon, E; Casarégola, S; de Montigny, J; Gaillardin, C; Lépingle, A; Llorente, B; Malpertuy, A; Neuvéglise, C; Ozier-Kalogeropoulos, O; Perrin, A; Potier, S; Souciet, J; Talla, E; Toffano-Nioche, C; Wésolowski-Louvel, M; Marck, C; Dujon, B

2000-12-22

330

Revisiting the classics: considering nonconsumptive effects in textbook examples of predator-prey interactions.  

PubMed

Predator effects on prey dynamics are conventionally studied by measuring changes in prey abundance attributed to consumption by predators. We revisit four classic examples of predator-prey systems often cited in textbooks and incorporate subsequent studies of nonconsumptive effects of predators (NCE), defined as changes in prey traits (e.g., behavior, growth, development) measured on an ecological time scale. Our review revealed that NCE were integral to explaining lynx-hare population dynamics in boreal forests, cascading effects of top predators in Wisconsin lakes, and cascading effects of killer whales and sea otters on kelp forests in nearshore marine habitats. The relative roles of consumption and NCE of wolves on moose and consequent indirect effects on plant communities of Isle Royale depended on climate oscillations. Nonconsumptive effects have not been explicitly tested to explain the link between planktonic alewives and the size structure of the zooplankton, nor have they been invoked to attribute keystone predator status in intertidal communities or elsewhere. We argue that both consumption and intimidation contribute to the total effects of keystone predators, and that characteristics of keystone consumers may differ from those of predators having predominantly NCE. Nonconsumptive effects are often considered as an afterthought to explain observations inconsistent with consumption-based theory. Consequently, NCE with the same sign as consumptive effects may be overlooked, even though they can affect the magnitude, rate, or scale of a prey response to predation and can have important management or conservation implications. Nonconsumptive effects may underlie other classic paradigms in ecology, such as delayed density dependence and predator-mediated prey coexistence. Revisiting classic studies enriches our understanding of predator-prey dynamics and provides compelling rationale for ramping up efforts to consider how NCE affect traditional predator-prey models based on consumption, and to compare the relative magnitude of consumptive and NCE of predators. PMID:18831163

Peckarsky, Barbara L; Abrams, Peter A; Bolnick, Daniel I; Dill, Lawrence M; Grabowski, Jonathan H; Luttbeg, Barney; Orrock, John L; Peacor, Scott D; Preisser, Evan L; Schmitz, Oswald J; Trussell, Geoffrey C

2008-09-01

331

The Nanometric and Micrometric Scales of the Structure and Mechanics of Materials Revisited: An Introduction to the Challenges of Fully Deterministic Numerical Descriptions  

Microsoft Academic Search

Nano-science and nano-technology as well as the fine modelling of the structure and mechanics of materials from the nanometric to the micrometric scales use descriptions ranging from the quantum to the statistical mechanics. This paper revisits the modelling at these scales and points out the main challenges related to the numerical solution of such models that some times are discrete

A. Ammar; P. Joyot

2008-01-01

332

Revisiting strategic communication's past to understand the present : Examining the direction and nature of communication on Fortune 500 and Philanthropy 400 web sites  

Microsoft Academic Search

Purpose – The purpose of this paper is to compare the communication styles on the web sites of a random sample of the top American corporations and non-profit organizations. By revisiting the traditional approach to understanding strategic communication, the four models of public relations provide insights into the direction and nature of organizational communication. Design\\/methodology\\/approach – A random sample of

Richard D. Waters; Jennifer L. Lemanski

2011-01-01

333

Revisiting the analytic theory of p-n junction impedance: improvements guided by computer simulation leading to a new equivalent circuit  

Microsoft Academic Search

We revisit the analytic derivation of the dc and low frequency ac behavior of the p-n step junction and suggest all preexisting treatments are flawed for three important reasons. First, not all contributions to the diode current are included. We derive a rigorous expression for each component of current that can be used to judge the completeness of existing analytic

Steven E. Laux; Karl Hess

1999-01-01

334

Factors influencing the intention to revisit a cultural attraction: The case study of the Museum of Modern and Contemporary Art in Rovereto  

Microsoft Academic Search

This paper analyses the different factors influencing the intention to revisit a cultural attraction with an application to the Museum for Modern and Contemporary Art (MART) in Rovereto, Italy. The empirical data were obtained from a survey undertaken in 2009 and a zero-truncated count data model is estimated. The findings reveal that sociodemographic characteristics positively influence the probability to return

Juan G. Brida; Marta Meleddu; Manuela Pulina

335

Revisiting the Role of Individual Variability in Population Persistence and Stability  

PubMed Central

Populations often exhibit a pronounced degree of individual variability and this can be important when constructing ecological models. In this paper, we revisit the role of inter-individual variability in population persistence and stability under predation pressure. As a case study, we consider interactions between a structured population of zooplankton grazers and their predators. Unlike previous structured population models, which only consider variability of individuals according to the age or body size, we focus on physiological and behavioural structuring. We first experimentally demonstrate a high degree of variation of individual consumption rates in three dominant species of herbivorous copepods (Calanus finmarchicus, Calanus glacialis, Calanus euxinus) and show that this disparity implies a pronounced variation in the consumption capacities of individuals. Then we construct a parsimonious predator-prey model which takes into account the intra-population variability of prey individuals according to behavioural traits: effectively, each organism has a ‘personality’ of its own. Our modelling results show that structuring of prey according to their growth rate and vulnerability to predation can dampen predator-prey cycles and enhance persistence of a species, even if the resource stock for prey is unlimited. The main mechanism of efficient top-down regulation is shown to work by letting the prey population become dominated by less vulnerable individuals when predator densities are high, while the trait distribution recovers when the predator densities are low.

Morozov, Andrew; Pasternak, Anna F.; Arashkevich, Elena G.

2013-01-01

336

Re-Visiting of Plentiful Food Sources and Food Search Strategies in Desert Ants  

PubMed Central

North African desert ants, Cataglyphis fortis, are established model organisms in animal navigation research. Cataglyphis re-visit plentiful feeding sites, but their decision to return to a feeder and the organization of food searches has been little studied. Here we provide a review of recent advances regarding this topic. At least two parameters determine the ants’ assessment of site quality, namely, amount of food available and reliability of food encounter on subsequent visits. The amount of food appears to be judged by the concentration of items at the food uptake site. Initially the amount of food in a feeder dominates the foragers’ decision to return, whereas learning about reliability takes precedence in the course of a few visits. The location of a worthwhile site is determined by the animals’ path integration system. In particular, the distance of the feeding site is memorized as the arithmetic average of the distances covered during the previous outbound and homebound journeys. Feeding sites that are small and inconspicuous cannot be approached directly with sufficient certainty, due to inevitable inaccuracies of the path integrator. Instead, desert ants steer downwind of the goal to encounter the odor plume emanating from the food and they follow this plume to the feeder. The angle steered downwind reflects the animals’ maximal navigation error and is adjusted according to experience. In summary, food searches of desert ants provide an unexpected wealth of features that may advance our understanding of search, navigation, and decision strategies. There are several aspects that warrant further scrutiny.

Wolf, Harald; Wittlinger, Matthias; Bolek, Siegfried

2012-01-01

337

Polyploidy and its effect on evolutionary success: old questions revisited with new tools.  

PubMed

Polyploidy, the condition of possessing more than two complete genomes in a cell, has intrigued biologists for almost a century. Polyploidy is found in many plants and some animal species and today we know that polyploidy has had a role in the evolution of all angiosperms. Despite its widespread occurrence, the direct effect of polyploidy on evolutionary success of a species is still largely unknown. Over the years many attractive hypotheses have been proposed in an attempt to assign functionality to the increased content of a duplicated genome. Among these hypotheses are the proposal that genome doubling confers distinct advantages to a polyploid and that these advantages allow polyploids to thrive in environments that pose challenges to the polyploid's diploid progenitors. This article revisits these long-standing questions and explores how the integration of recent genomic developments with ecological, physiological and evolutionary perspectives has contributed to addressing unresolved problems about the role of polyploidy. Although unsatisfactory, the current conclusion has to be that despite significant progress, there still isn't enough information to unequivocally answer many unresolved questions about cause and effect of polyploidy on evolutionary success of a species. There is, however, reason to believe that the increasingly integrative approaches discussed here should allow us in the future to make more direct connections between the effects of polyploidy on the genome and the responses this condition elicits from the organism living in its natural environment. PMID:23149459

Madlung, A

2012-11-14

338

Local geographic distributions of bumble bees near Crested Butte, Colorado: competition and community structure revisited.  

PubMed

Surveys in 1974 of bumble bee species distributions along elevational gradients (Pyke 1982) were revisited to reevaluate the original conclusion that coexistence of bumble bee species can be ascribed to niche differentiation, primarily on the basis of proboscis lengths and the associated corolla lengths of visited flowers. Each bee species largely visited a few plant species, which were preferred relative to other species. Bee proboscis length was correlated with average corolla length of visited flowers, but not when species with relatively long and short proboscises were considered separately. Bumble bee abundance was affected by presence or absence of major plant species and, contrary to the interpretation of Pyke (1982), elevation, with neither factor dominating. Multimodal distributions of proboscis lengths and altitudinal replacement of bee species of similar proboscis length were consistent with the original hypothesis that bumble bee species compete for floral resources, especially nectar, and cannot coexist if proboscis lengths are too similar, unless one species is a "nectar robber" and hence has exclusive use of some floral resources. However, observed overlap in elevational distributions of bumble bee species with similar proboscis length cannot be reconciled with this hypothesis unless other phenomena are invoked. PMID:23321080

Pyke, Graham H; Inouye, David W; Thomson, James D

2012-12-01

339

A matching problem revisited for stability analysis of resistive wall modes in flowing plasmas  

SciTech Connect

The classical matching problem for magnetohydrodynamic stability analysis is revisited to study effects of the plasma flow on the resistive wall modes (RWMs). The Newcomb equation, which describes the marginal states and governs the regions except for the resonant surface, is generalized to analyze the stability of flowing plasmas. When there exists no flow, the singular point of the Newcomb equation and the resonant surface degenerate into the rational surface. The location of the rational surface is prescribed by the equilibrium, hence the inner layer, which must contain the resonant surface, can be set a priori. When the flow exists, the singular point of the Newcomb equation splits in two due to the Doppler shift. Additionally, the resonant surface deviates from the singular points and the rational surface if the resonant eigenmode has a real frequency. Since the location of the resonant surface depends on the unknown real frequency, it can be determined only a posteriori. Hence the classical asymptotic matching method cannot be applied. This paper shows that a new matching method that generalizes the asymptotic one to use the inner layer with finite width works well for the stability analysis of flowing plasmas. If the real frequency is limited in a certain range such as the RWM case, the resonance occurs somewhere in the finite region around the singular points, hence the inner layer with finite width can capture the resonant surface.

Shiraishi, J.; Tokuda, S.; Aiba, N. [Japan Atomic Energy Agency, 801-1 Mukouyama, Naka-shi, Ibaraki-ken 311-0193 (Japan)

2010-01-15

340

TYPE II-P SUPERNOVAE AS STANDARD CANDLES: THE SDSS-II SAMPLE REVISITED  

SciTech Connect

We revisit the observed correlation between the H{beta} and Fe II velocities for Type II-P supernovae (SNe II-P) using 28 optical spectra of 13 SNe II-P and demonstrate that it is well modeled by a linear relation with a dispersion of about 300 km s{sup -1}. Using this correlation, we re-analyze the publicly available sample of SNe II-P compiled by D'Andrea et al. and find a Hubble diagram with an intrinsic scatter of 11% in distance, which is nearly as tight as that measured before their sample is added to the existing set. The larger scatter reported in their work is found to be systematic, and most of it can be alleviated by measuring the H{beta} rather than Fe II velocities, due to the low signal-to-noise ratios and early epochs at which many of the optical spectra were obtained. Their sample, while supporting the mounting evidence that SNe II-P are good cosmic rulers, is biased toward intrinsically brighter objects and is not a suitable set to improve upon SN II-P correlation parameters. This will await a dedicated survey.

Poznanski, Dovi; Nugent, Peter E. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Filippenko, Alexei V., E-mail: dovi@berkeley.ed [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

2010-10-01

341

Revisiting adoption of high transmission PSM: pros, cons and path forward  

NASA Astrophysics Data System (ADS)

High transmission attenuated phase shift masks (Hi-T PSM) have been successfully applied in volume manufacturing for certain memory devices. Moreover, numerous studies have shown the potential benefits of Hi-T PSM for specific lithography applications. In this paper, the potential for extending Hi-T PSM to logic devices, is revisited with an emphasis on understanding layout, transmission, and manufacturing of Hi-T PSM versus traditional 6% embedded attenuated phase shift mask (EAPSM). Simulations on various layouts show Hi-T PSM has advantage over EAPSM in low duty cycle line patterns and high duty cycle space patterns. The overall process window can be enhanced when Hi- T PSM is combined with optimized optical proximity correction (OPC), sub-resolution assist features (SRAF), and source illumination. Therefore, Hi-T PSM may be a viable and lower cost alternative to other complex resolution enhancement technology (RET) approaches. Aerial image measurement system (AIMS) results on test masks, based on an inverse lithography technology (ILT) generated layout, confirm the simulation results. New advancement in high transmission blanks also make low topography Hi-T PSM a reality, which can minimize scattering effects in high NA lithography.

Ma, Z. Mark; McDonald, Steve; Progler, Chris

2009-12-01

342

Revisiting the Reactivity of Uracil During Collision Induced Dissociation: Tautomerism and Charge-Directed Processes  

NASA Astrophysics Data System (ADS)

In our recent work towards the nontarget identification of products of nucleic acid (NA) damage in urine, we have found previous work describing the dissociation of NA bases not adequate to fully explain their observed reactivity. Here we revisit the gas-phase chemistry of protonated uracil (U) during collision induced dissociation (CID) using two modern tandem mass spectrometry techniques; quadrupole ion trap (QIT) and quadrupole time of flight (Q-TOF). We present detailed mechanistic proposals that account for all observed products of our experiments and from previous isotope labeling data, and that are supported by previous ion spectroscopy results and theoretical work. The diverse product-ions of U cannot be explained adequately by only considering the lowest energy form of protonated U as a precursor. The tautomers adopted by U during collisional excitation make it possible to relate the complex reactivity observed to reasonable mechanistic proposals and feasible product-ion structures for this small highly conjugated heterocycle. These reactions proceed from four different stable tautomers, which are excited to a specific activated precursor from which dissociation can occur via a charge-directed process through a favorable transition state to give a stabilized product. Understanding the chemistry of uracil at this level will facilitate the identification of new modified uracil derivatives in biological samples based solely on their reactivity during CID. Our integrated approach to describing ion dissociation is widely applicable to other NA bases and similar classes of biomolecules.

Beach, Daniel G.; Gabryelski, Wojciech

2012-05-01

343

Revisiting the Scale Length-?0 Plane and the Freeman Law in the Local Universe  

NASA Astrophysics Data System (ADS)

We have used Virtual Observatory technology to analyze the disk scale length rd and central surface brightness ?0 for a sample of 29,955 bright disk galaxies from the Sloan Digital Sky Survey. We use the results in the r band and revisit the relation between these parameters and the galaxy morphology, and find the average value lang?0rang = 20.2 ± 0.7 mag arcsec-2. We confirm that late-type spirals populate the lower left corner of the rd -?0 plane and that the early and intermediate spirals are mixed in this diagram, with disky ellipticals at the top left corner. We further investigate the Freeman Law and confirm that it indeed defines an upper limit for ?0 in bright disk galaxies with r mag < 17.0, and that disks in late-type spirals (T >= 6) have fainter central surface brightness. Our results are based on a volume-corrected sample of galaxies in the local universe (z < 0.3) that is two orders of magnitudes larger than any sample previously studied and deliver statistically significant implications that provide a comprehensive test bed for future theoretical studies and numerical simulations of galaxy formation and evolution.

Fathi, Kambiz

2010-10-01

344

The uranyl ion revisited: the electric field gradient at U as a probe of environmental effects  

NASA Astrophysics Data System (ADS)

The experimental electric field gradient (EFG) at the U nucleus in uranyl is positive. It has been pointed out by Pyykkö that this could be a signature of a hole in the 6p shell induced by the strong bonding to the axial O atoms. We have revisited this issue with the help of relativistic density functional calculations, including accurate ZORA-4 calculations of the EFG. We confirm the existence of a 6p hole, with a positive contribution to the EFG, but we still find the EFG in the free uranyl ion to be negative due to the non-spherical electron distribution in the valence 5f shell caused by the bonding to the oxygens. A positive EFG only results in our calculations from the effect of the crystal environment of the uranyl ion, i.e. the coordination of three nitrate groups in the equatorial plane. Again the extended nature of 6p plays a key role, with an important positive contribution to the EFG coming from 6p tails in the high-lying electron pair orbitals of the closed shell nitrate ligands due to the orthogonality requirement. A further contribution comes from electron donation by the nitrate groups into the U 5? and 6d? orbitals which both have their lobes in the equatorial plane. Our findings highlight the sensitivity of the EFG to the environment, through effects on the upper valence electronic structure.

Belanzoni, Paola; Baerends, Evert Jan; van Lenthe, Erik

345

Revisiting Purine-Histidine Cross-Pathway Regulation in Saccharomyces cerevisiae  

PubMed Central

Because some metabolic intermediates are involved in more than one pathway, crosstalk between pathways is crucial to maintaining homeostasis. AMP and histidine biosynthesis pathways are coregulated at the transcriptional level in response to adenine availability. 5?-Phosphoribosyl-4-carboxamide-5-aminoimidazole (AICAR), a metabolic intermediate at the crossroads between these two pathways, is shown here to be critical for activation of the transcriptional response in the absence of adenine. In this study, we show that both AMP and histidine pathways significantly contribute to AICAR synthesis. Furthermore, we show that upregulation of the histidine pathway clearly interferes with regulation of the AMP pathway, thus providing an explanation for the regulatory crosstalk between these pathways. Finally, we revisit the histidine auxotrophy of ade3 or ade16 ade17 mutants. Interestingly, overexpression of PMU1, encoding a potential phosphomutase, partially suppresses the histidine requirement of an ade3 ade16 ade17 triple mutant, most probably by reducing the level of AICAR in this mutant. Together our data clearly establish that AICAR is not just a metabolic intermediate but also acts as a true regulatory molecule.

Rebora, Karine; Laloo, Benoit; Daignan-Fornier, Bertrand

2005-01-01

346

Fertility control in historical China revisited: New Methods for an Old Debate  

PubMed Central

We revisit the debate over deliberate control of reproduction in historical China through a reanalysis of data from the Qing (1644-911) Imperial Lineage that accounts for physiological or other differences between couples that affected their chances of having children. Even though studies of contemporary and historical European fertility suggest that failing to control for such differences may obscure evidence of parity-specific control, previous studies of historical Chinese fertility have not accounted for them. We show that in the Lineage, failure to account for such differences leads the association between number of children already born and the chances of having another birth to appear to be positive, but that once they are accounted for properly, the relationship is inverted. Based on this, we conclude that lineage members adjusted their reproductive behavior based on the number of children. We also show that the sex composition and survival of previous births affected reproductive behavior. We conclude by suggesting that one way forward in the ongoing debate over fertility control in historical China is through application of such methods to other datasets and comparison of results. We also suggest that progress in the debate over fertility in historical China has been impeded by confusion over the definition of fertility control, so that some behaviors are recognized as fertility control by some parties in the debate but not others.

Lee, James Z.

2010-01-01

347

The Neogene astronomical tuned (polarity) timescale between 5 and 14 Ma revisited  

NASA Astrophysics Data System (ADS)

The characteristic cyclic sedimentary sequence of ODP Leg 154 Sites 925-929 from the Ceara Rise in the western equatorial Atlantic allowed the construction of an astronomical-tuned geologic time scale for the entire Neogene (Shackleton et al. 1999). During the Leg it became already apparent that the splice of Site 926 contains some complications, which could affect the orbital tuning and hence the paleoclimatic interpretation of the record (Shackleton et al. 1997). This record is of major importance for biostratigraphic and paleoclimatologic investigations and, together with Mediterranean land-based sections, forms the backbone of the standard Neogene Geologic Time Scale (Lourens et al. 2004). We revisited the Ceara Rise physical property records and established a revised splice and orbital tuning, using the La2004 solution (Laskar et al. 2004). In addition, we evaluated the tuning by applying different values for the tidal dissipation parameter of the Earth-Moon system. According to our new tuning results, the eccentricity pattern of the physical property records resembles the orbital eccentricity very well; biostratigraphic datums differ from the initial tuning in the order of 100 kyr from ca. 10.5 to 11.2 and ca. 13.4 to 13.7 Ma. Finally, we compared our revised time scale with new data of the tuned Monte dei Corvi section in the Mediterranean, which contained a reliable magnetostratigraphy. This allowed us to improve the accuracy of magnetic reversals ages between 5 and 14 Ma.

Zeeden, C.; Hilgen, F.; Lourens, L.; Westerhold, T.; Roehl, U.; Huesing, S.

2011-12-01

348

Chemical composition and structure of peritubular and intertubular human dentin revisited  

PubMed Central

Objective Currently there is still a debate about whether peritubular dentin (PTD) is non-collageneous or collageneous tissue. The chemical composition and structure of human PTD and intertubular dentin (ITD) was re-visited in this study. Design The dentin tubular region including ITD and PTD prepared from human third molars was in-situ detected by means of micro-Raman spectroscopy (?Rs) and atomic force microscopy (AFM). Results From the ?Rs study, it was found that the mineral/matrix ratios (phosphate vs CH2) in PTD were ~3 times of those in ITD. For the mineral, the differences between PTD and ITD were small, but still detectable. For the organic matrix, the intensity ratios of amide III to CH2 in ITD were ~1.5 times of those in PTD, indicating the structural differences. In addition, there was a higher proline/hydroxyproline content in ITD than that in PTD. However, the overall Raman peak contour in the amide regions (I & III) was similar, indicating collagen might still exist in both the ITD and PTD. An in situ AFM observation of the dentinal tubular region during EDTA etching confirmed that dentin collagen ran across from the ITD into the PTD. Conclusion A phenomenon similar to that observed in the dentin-enamel junction is proposed to explain the above results. It is demonstrated that the ?Rs-AFM approach can be used to provide an insight into the structure of small dental tissues at the micron or sub-micron scale.

Xu, Changqi; Wang, Yong

2011-01-01

349

Revisiting properties of ferroelectric and multiferroic thin films under tensile strain from first principles.  

PubMed

First-principles calculations are performed to revisit properties of (001) epitaxial BiFeO(3) (BFO) and PbTiO(3) thin films under tensile strain. While these two films possess different ground states when experiencing no misfit strain, they both exhibit the same, previously unknown phase for tensile strains above ?5% at T = 0 K. This novel state is of orthorhombic Pmc2(1) symmetry and is macroscopically characterized by a large in-plane polarization coexisting with oxygen octahedra tilting in-phase about the out-of-plane direction. On a microscopic point of view, this Pmc2(1) state exhibits short atomic bonds and zigzag cation displacement patterns, unlike conventional ferroelectric phases and typical domains. Such unusual inhomogeneous patterns originate from the coexistence of polar and antiferroelectric distortions having the same magnitude and lead BFO films to be the first known material for which orbital ordering coexists with a large polarization. Furthermore, this Pmc2(1) state is also found in other perovskite films under tensile strain, which emphasizes its generality. PMID:23006208

Yang, Yurong; Ren, Wei; Stengel, Massimiliano; Yan, X H; Bellaiche, L

2012-08-02

350

Inverse neutrinoless double beta decay revisited: Neutrinos, Higgs triplets, and a muon collider  

SciTech Connect

We revisit the process of inverse neutrinoless double beta decay (e{sup -}e{sup -{yields}}W{sup -}W{sup -}) at future linear colliders. The cases of Majorana neutrino and Higgs triplet exchange are considered. We also discuss the processes e{sup -{mu}-{yields}}W{sup -}W{sup -} and {mu}{sup -{mu}-{yields}}W{sup -}W{sup -}, which are motivated by the possibility of muon colliders. For heavy neutrino exchange, we show that masses up to 10{sup 6} (10{sup 5}) GeV could be probed for ee and e{mu} machines, respectively. The stringent limits for mixing of heavy neutrinos with muons render {mu}{sup -{mu}-{yields}}W{sup -}W{sup -} less promising, even though this process is not constrained by limits from neutrinoless double beta decay. If Higgs triplets are responsible for inverse neutrinoless double beta decay, observable signals are only possible if a very narrow resonance is met. We also consider unitarity aspects of the process in case both Higgs triplets and neutrinos are exchanged. An exact seesaw relation connecting low energy data with heavy neutrino and triplet parameters is found.

Rodejohann, Werner [Max-Planck-Institut fuer Kernphysik, Postfach 103980, D-69029 Heidelberg (Germany)

2010-06-01

351

Perceived parenting style and adolescent adjustment: revisiting directions of effects and the role of parental knowledge.  

PubMed

In the present research on parenting and adolescent behavior, there is much focus on reciprocal, bidirectional, and transactional processes, but parenting-style research still adheres to a unidirectional perspective in which parents affect youth behavior but are unaffected by it. In addition, many of the most cited parenting-style studies have used measures of parental behavioral control that are questionable because they include measures of parental knowledge. The goals of this study were to determine whether including knowledge items might have affected results of past studies and to test the unidirectional assumption. Data were from 978 adolescents participating in a longitudinal study. Parenting-style and adolescent adjustment measures at 2 time points were used, with a 2-year interval between time points. A variety of internal and external adjustment measures were used. Results showed that including knowledge items in measures of parental behavioral control elevated links between behavioral control and adjustment. Thus, the results and conclusions of many of the most highly cited studies are likely to have been stronger than if the measures had focused strictly on parental behavior. In addition, adolescent adjustment predicted changes in authoritative and neglectful parenting styles more robustly than these styles predicted changes in adolescent adjustment. Adolescent adjustment also predicted changes in authoritativeness more robustly than authoritativeness predicted changes in adjustment. Thus, parenting style cannot be seen as independent of the adolescent. In summary, both the theoretical premises of parenting-style research and the prior findings should be revisited. PMID:22448987

Kerr, Margaret; Stattin, Håkan; Ozdemir, Metin

2012-03-26

352

A plasma vortex revisited: The importance of including ionospheric conductivity measurements  

NASA Astrophysics Data System (ADS)

In an earlier paper [Kosch et al., 1998], simultaneous all-sky TV imager and Scandinavian Twin Auroral Radar Experiment (STARE) observations of an ionospheric plasma vortex located poleward of an auroral arc were presented. The vortex is associated with a sudden brightening of the arc and corresponds to an ionospheric region of diverging horizontal electric fields, which is equivalent to a downward field-aligned current (FAC), i.e., the closure current for the upward current above the arc. This event has been revisited because of the subsequent availability of data from the Scandinavian Magnetometer Array. These data, combined with STARE electric fields, have been used to determine the real ionospheric conductance distribution throughout the field of view. As a result, a more realistic, quantitative picture of the current system associated with the arc is obtained than was possible in an earlier model based on an assumed constant conductance. In particular, a complete macroscopic electrodynamic description of a plasma vortex, composed of ionospheric conductances, true horizontal currents, and FACs, is obtained for the first time. It is shown that the plasma vortex corresponds to an area of decreased conductance, thus broadening the FAC distribution and reducing the current density compared to the earlier results. The study illustrates that horizontal conductance gradients should not be neglected when computing FACs.

Kosch, M. J.; Amm, O.; Scourfield, M. W. J.

2000-11-01

353

Radiative transfer model for aerosols at infrared wavelengths for passive remote sensing applications: revisited.  

PubMed

We introduced a two-dimensional radiative transfer model for aerosols in the thermal infrared [Appl. Opt.45, 6860-6875 (2006)APOPAI0003-693510.1364/AO.45.006860]. In that paper we superimposed two orthogonal plane-parallel layers to compute the radiance due to a two-dimensional (2D) rectangular aerosol cloud. In this paper we revisit the model and correct an error in the interaction of the two layers. We derive new expressions relating to the signal content of the radiance from an aerosol cloud based on the concept of five directional thermal contrasts: four for the 2D diffuse radiance and one for direct radiance along the line of sight. The new expressions give additional insight on the radiative transfer processes within the cloud. Simulations for Bacillus subtilis var. niger (BG) bioaerosol and dustlike kaolin aerosol clouds are compared and contrasted for two geometries: an airborne sensor looking down and a ground-based sensor looking up. Simulation results suggest that aerosol cloud detection from an airborne platform may be more challenging than for a ground-based sensor and that the detection of an aerosol cloud in emission mode (negative direct thermal contrast) is not the same as the detection of an aerosol cloud in absorption mode (positive direct thermal contrast). PMID:19122735

Ben-David, Avishai; Davidson, Charles E; Embury, Janon F

2008-11-01

354

'The Ethiopian famine' revisited: band aid and the antipolitics of celebrity humanitarian action.  

PubMed

In many ways the Ethiopian famine of 1983-85 has served as a watershed with respect to humanitarian action. One of its lasting legacies has been the emergence of Band Aid and the subsequent increase in celebrity humanitarianism. A revisiting of the events of 1983-85 occurred in 2010 during a dispute in which it was alleged that a portion of the donations of Band Aid were spent on arms purchases. This paper takes this controversy as its starting point. It goes on to use the theoretical reflections of Giorgio Agamben to consider the dynamics that unfolded during the Ethiopian famine of 1983-85 and to analyse the underlying conceptualisation behind the emergence of Band Aid-type celebrity humanitarianism. The paper concludes with some wider thoughts on how the in essence antipolitical agenda of celebrity humanitarian action is transported into the everyday understanding of 'African disaster', resulting ultimately in the perpetuation of hegemonic control by the global North. PMID:23067379

Müller, Tanja R

2012-10-16

355

Safe removal of an encrusted nephrostomy tube using a vascular sheath: a technique revisited.  

PubMed

With the advent of interventional radiology and the decrease in mortality from chronic ailments, especially malignancy, percutaneous nephrostomy has become a commonly used safe technique for temporary relief of renal tract obstruction or for urinary diversion. However, these are associated with risks of infection, particularly septicaemia, colonisation, and blockage. Another significant complication is difficulty in removal due to encrustation. We describe a useful technique used in our department for the past few years and cite four cases of variable presentation and complexity for removal of an encrusted nephrostomy tube. No mention of this technique was found recent literature. An almost similar technique was described in the 1980s "Pollack and Banner (Radiology 145:203-205, 1982), Baron and McClennan (Radiology 141:824, 1981)". It is possible that experienced operators may have used this technique. We revisit it with pictographic representation, describing its use with currently available equipment, for benefit of operators who are not aware of this technique. PMID:23443251

Farooq, Ammad; Agarwal, Sanjay; Jones, Vaughan

2013-02-27

356

The Eating Attitudes Test-26 revisited using exploratory structural equation modeling.  

PubMed

Most previous studies have failed to replicate the original factor structure of the 26-item version of the Eating Attitudes Test (EAT-26) among community samples of adolescents. The main objective of the present series of four studies (n?=?2178) was to revisit the factor structure of this instrument among mixed gender community samples of adolescents using both exploratory structural equation modeling (ESEM) and confirmatory factor analysis (CFA). First, results from the ESEM analyses provided satisfactory goodness-of-fit statistics and reliability coefficients for a six-factor model of the EAT with 18 items (EAT-18) closely corresponding to the original seven-factor structure proposed for the 40-item version of the EAT. Second, these analyses were satisfactorily replicated among a new sample of community adolescents using CFA. The results confirmed the factor loading and intercept invariance of this model across gender and age groups (i.e., early and late adolescence), as well as the complete invariance of the EAT-18 measurement model between ethnicities (i.e., European versus African origins) and across weight categories (i.e., underweight, normal weight and overweight). Finally, the last study provided support for convergent validity of the EAT-18 with the Eating Disorder Inventory and with instruments measuring global self-esteem, physical appearance, social physique anxiety and fear of negative appearance evaluation. PMID:23344702

Maïano, Christophe; Morin, Alexandre J S; Lanfranchi, Marie-Christine; Therme, Pierre

2013-07-01

357

Positive and negative analyte ion yield in matrix-assisted laser desorption/ionization revisited  

NASA Astrophysics Data System (ADS)

The most commonly accepted model for the formation of analyte ions in MALDI-MS assumes a primary ionization of the matrix e.g., by photoionization, leading among others to stable protonated and deprotonated matrix ions, respectively. Peptide and protein ions are then formed by secondary proton transfer reactions in the expanding plume. This model had been checked experimentally by comparing the yield of positive to negative ions of three peptides (Bradykinin, Angiotensin I and Fibrinopeptide A) and six matrices ([alpha]-cyano-4-hydroxycinnamicacid (CHCA), 2,5-dihydroxybenzoicacid (DHB), 6-aza-2-thiothymine (ATT), 4-nitroaniline (4-NA), 2-amino-5-nitro-4-picoline (ANP), 5-aminoquinolione (5-AQ)), differing in gas-phase basicity by about 100 kJ/mole [M. Dashtiev, E. Wäfler, U. Röhling, M. Gorshkov, F. Hillenkamp, R. Zenobi, Int. J. Mass Spetrom. 268 (2007) 122]. The data have been revisited for a more general and in-depth analysis. Model predictions are presented for a wide range of experimental parameters, in particular for ranges of the gas-phase basicity and acidity of analyte and matrix and for different molar ratios of analyte to matrix as well as the yield of primary matrix ions. It is shown that the observed ion yields cannot be explained by any single and consistent set of parameters. It is concluded that the existing simple model needs be modified to fully explain the experimental findings. Such modifications should primarily address the formation of negative matrix and analyte ions.

Hillenkamp, F.; Wäfler, E.; Jecklin, M. C.; Zenobi, R.

2009-08-01

358

Revisiting the method to obtain the mechanical properties of hydrided fuel cladding in the hoop direction  

NASA Astrophysics Data System (ADS)

The method reported in the literature to calculate the stress-strain curve of nuclear fuel cladding from ring tensile test is revisited in this paper and a new alternative is presented. In the former method, two universal curves are introduced under the assumption of small strain. In this paper it is shown that these curves are not universal, but material-dependent if geometric nonlinearity is taken into account. The new method is valid beyond small strains, takes geometric nonlinearity into consideration and does not need universal curves. The stress-strain curves in the hoop direction are determined by combining numerical calculations with experimental results in a convergent loop. To this end, ring tensile tests were performed in unirradiated hydrogen-charged samples. The agreement among the simulations and the experimental results is excellent for the range of concentrations tested (up to 2000 wppm hydrogen). The calculated stress-strain curves show that the mechanical properties do not depend strongly on the hydrogen concentration, and that no noticeable strain hardening occurs. However, ductility decreases with the hydrogen concentration, especially beyond 500 wppm hydrogen. The fractographic results indicate that as-received samples fail in a ductile fashion, whereas quasicleavage is observed in the hydrogen-charged samples.

Martín-Rengel, M. A.; Gómez Sánchez, F. J.; Ruiz-Hervías, J.; Caballero, L.; Valiente, A.

2012-10-01

359

Revisit of combined parallel-beam/cone-beam or fan-beam/cone-beam imaging  

PubMed Central

Purpose: This aim of this paper is to revisit the parallel-beam/cone-beam or fan-beam/cone-beam imaging configuration, and to investigate whether this configuration has any advantages. Methods: Twenty years ago, it was suggested to simultaneously use a parallel-beam (or a fan-beam) collimator and a cone-beam collimator to acquire single photon emission computed tomography data. The motivation was that the parallel-beam (or the fan-beam) collimator can provide sufficient sampling, while the cone-beam collimator is able to provide higher photon counts. Even with higher total counts, this hybrid system does not give significant improvement (if any) in terms of image noise and artifacts reduction. If a conventional iterative maximum-likelihood expectation-maximization algorithm is used to reconstruct the image, the resultant reconstruction may be worse than the parallel-beam-only (or fan-beam-only) system. This paper uses the singular value decomposition (SVD) analysis to explain this phenomenon. Results: The SVD results indicate that the parallel-beam-only and the fan-beam-only system outperform the combined systems. Conclusions: The optimal imaging system does not necessary to be the one that generates the projections with highest signal-to-noise ratio and best resolution.

Zeng, Gengsheng L.

2013-01-01

360

Re-visiting of plentiful food sources and food search strategies in desert ants.  

PubMed

North African desert ants, Cataglyphis fortis, are established model organisms in animal navigation research. Cataglyphis re-visit plentiful feeding sites, but their decision to return to a feeder and the organization of food searches has been little studied. Here we provide a review of recent advances regarding this topic. At least two parameters determine the ants' assessment of site quality, namely, amount of food available and reliability of food encounter on subsequent visits. The amount of food appears to be judged by the concentration of items at the food uptake site. Initially the amount of food in a feeder dominates the foragers' decision to return, whereas learning about reliability takes precedence in the course of a few visits. The location of a worthwhile site is determined by the animals' path integration system. In particular, the distance of the feeding site is memorized as the arithmetic average of the distances covered during the previous outbound and homebound journeys. Feeding sites that are small and inconspicuous cannot be approached directly with sufficient certainty, due to inevitable inaccuracies of the path integrator. Instead, desert ants steer downwind of the goal to encounter the odor plume emanating from the food and they follow this plume to the feeder. The angle steered downwind reflects the animals' maximal navigation error and is adjusted according to experience. In summary, food searches of desert ants provide an unexpected wealth of features that may advance our understanding of search, navigation, and decision strategies. There are several aspects that warrant further scrutiny. PMID:22783163

Wolf, Harald; Wittlinger, Matthias; Bolek, Siegfried

2012-07-05

361

Revisiting XENON100's constraints (and signals?) for low-mass dark matter  

NASA Astrophysics Data System (ADS)

Although observations made with the CoGeNT and CDMS experiments have been interpreted as possible signals of low-mass ( ~ 7–10 GeV) dark matter particles, constraints from the XENON100 collaboration appear to be incompatible with this hypothesis, at least at face value. In this paper, we revisit XENON100's constraint on dark matter in this mass range, and consider how various uncertainties and assumptions made might alter this conclusion. We also note that while XENON100's two nuclear recoil candidates each exhibit very low ratios of ionization-to-scintillation signals, making them difficult to attribute to known electronic or neutron backgrounds, they are consistent with originating from dark matter particles in the mass range favored by CoGeNT and CDMS. We argue that with lower, but not implausible, values for the relative scintillation efficiency of liquid xenon (Leff), and the suppression of the scintillation signal in liquid xenon at XENON100's electric field (Snr), these two events could consistently arise from dark matter particles with a mass and cross section in the range favored by CoGeNT and CDMS. If this interpretation is correct, we predict that the LUX experiment, with a significantly higher light yield than XENON100, should observe dark matter induced events at an observable rate of ~ 3–24 per month.

Hooper, Dan

2013-09-01

362

Phobos 2/ASPERA data revisited: Planetary ion escape rate from Mars near the 1989 solar maximum  

NASA Astrophysics Data System (ADS)

Insights about the near-Mars space environment from Mars Express observations have motivated a revisit of the Phobos 2/ASPERA ion data from 1989. We have expanded the analysis to now include all usable heavy ion (O+, O2+, CO2+) measurements from the circular orbits of Phobos 2. Phobos 2/ASPERA ion fluxes in the Martian tail are compared with previous results obtained by the instruments on Phobos 2. Further validation of the measurement results is obtained by comparing IMP-8 and Phobos 2/ASPERA solar wind ion fluxes, taking into account the time lag between Earth and Mars. Heavy ion flux measurements from 18 circular equatorial orbits around Mars are bin-averaged to a grid, using the MSE (electric field) frame of reference. The binned data are subsequently integrated to determine the total escape rate of planetary ions. From this we derive a total planetary heavy ion escape rate of (2-3) × 1025 s-1 from Mars for the 1989 solar maximum.

Ramstad, Robin; Futaana, Yoshifumi; Barabash, Stas; Nilsson, Hans; Martin Del Campo B, Sergio; Lundin, Rickard; Schwingenschuh, Konrad

2013-02-01

363

Revisiting the Recommended Geometry for the Diametrally Compressed Ceramic C-Ring Specimen  

SciTech Connect

A study conducted several years ago found that a stated allowable width/thickness (b/t) ratio in ASTM C1323 (Standard Test Method for Ultimate Strength of Advanced Ceramics with Diametrally Compressed C-Ring Specimens at Ambient Temperature) could ultimately cause the prediction of a non-conservative probability of survival when the measured C-ring strength was scaled to a different size. Because of that problem, this study sought to reevaluate the stress state and geometry of the C-ring specimen and suggest changes to ASTM C1323 that would resolve that issue. Elasticity, mechanics of materials, and finite element solutions were revisited with the C ring geometry. To avoid the introduction of more than 2% error, it was determined that the C ring width/thickness (b/t) ratio should range between 1-3 and that its inner radius/outer radius (ri/ro) ratio should range between 0.50-0.95. ASTM C1323 presently allows for b/t to be as large as 4 so that ratio should be reduced to 3.

Jadaan, Osama M. [University of Wisconsin, Platteville; Wereszczak, Andrew A [ORNL

2009-04-01

364

Indiana v. Davis: revisiting due process rights of permanently incompetent defendants.  

PubMed

With its landmark Jackson v. Indiana (406 U.S. 715 (1972)) decision, the United States Supreme Court ruled that states may not indefinitely confine criminal defendants solely on the basis of incompetence to stand trial. While this decision led to widespread state statutory and procedural changes, the Jackson court left unresolved whether states could indefinitely maintain criminal charges against incompetent defendants. Nearly four decades after the Jackson decision, the Indiana Supreme Court finally revisited this question in Indiana v. Davis (898 N.E.2d. 281 (Ind. 2008)), unanimously ruling that holding criminal charges over the head of a permanently incompetent defendant, when her pretrial confinement extended beyond the maximum period of any sentence the trial court could impose, violated the basic notions of fundamental fairness embodied in the Due Process Clause of the Fourteenth Amendment. In this analysis of Indiana v. Davis, the facts of the case and the court's rationale for its decision are discussed. This unique ruling is considered in light of the questions resolved and still unanswered since Jackson v. Indiana. PMID:19767504

Morris, Douglas R; Parker, George F

2009-01-01

365

Vibrational Dynamics of Ferric MbCN-A Revisit by Resonance Raman and Vibrational Coherence Spectroscopy  

NASA Astrophysics Data System (ADS)

Ultrafast pump-probe spectroscopy has indicated that there exists a photoproduct state following the excitation of ferric MbCN^[1][2]. This excited state decays with a time constant of 3.6 ps^[1]. Previous studies on this system have suggested that in this photoproduct state, the heme is either (i) still six-coordinated but vibrationally hot in the electronic ground state^[1] or (ii) the proximal histidine residue (His93) is transiently dissociated, while CN^- is still bound^[2]. Recent resonance Raman measurements on ferric MbCN in static solution yield spectra that are very similar to ferric myoglobin, which has His93 and a water molecule as axial ligands. This indicates that a water molecule replaces CN^- in ferric MbCN under continuous laser excitation. Photolysis of CN^- from the heme iron is necessary to make this happen, which is not consistent with the above two suggestions. In this presentation we will revisit the dynamics of ferric MbCN with resonance Raman and vibrational coherence spectroscopy and try to explain how a water molecule competes with CN^- in binding to the heme under photo excitation^[3]. References: [1]Helbing J. et al., Biophys J, vol 87, 1881(2004) [2]Gruia F. et al., Biophys J, vol 94, 2252(2008) [3]Cao W. et al., Biochemistry, vol 40, 5728(2001)

Zeng, Weiqiao; Sun, Yuhan; Benabbas, Abdelkrim; Champion, Paul M.

2012-02-01

366

Revisiting the Spiral Density Wave Paradigm in M51 with PAWS  

NASA Astrophysics Data System (ADS)

The interacting Whirlpool galaxy M51 is a favorite test-bed for spiral arm density wave theories, and studies of the spiral morphology and kinematics show evidence for the offset alignment of the gaseous, young and old stellar tracers predicted by theory, as well as strong non-circular gas streaming motions. Now, the unparalleled high resolution of the PAWS (PdBI Arcsecond Whirlpool Survey, PI:Schinnerer) data, combined with exceptional multi-wavelength coverage, makes it an ideal target for revisiting the density wave picture and for examining the influence of bar and spiral instabilities on secular evolution. We present an updated view of the current dynamical state of the system, with particular emphasis on GMC scales. Gas kinematics at these scales--available for the first time in a spiral outside the Local Group--are a critical tool for assessing the influence of spiral arms on the organization of the ISM. To interpret the role of pressure and shear on GMC formation and evolution, we combine these data with a 2D map of spiral arm torques newly derived from the stellar mass distribution mapped with S4G 3.6 and 4.5 ?m images. We also compare gas inflow and star formation rates throughout the disk, assembling a view of the spatial-dependence of consumption timescales for the current gas reservoir.

Meidt, Sharon; Schinnerer, E.; Garcia-Burillo, S.; Hughes, A.; Colombo, D.; Pety, J.; Leroy, A.; Schuster, K.; Kramer, C.; Dumas, G.; Dobbs, C.; Thompson, T.

2012-01-01

367

Phobos 2/ASPERA data revisited: Planetary ion escape rate from Mars near the 1989 solar maximum  

NASA Astrophysics Data System (ADS)

Insights about the near-Mars space environment from Mars Express observations have motivated a revisit of the ASPERA-Phobos 2 ion data from 1989. The Sun's more active past makes the escape rate measured during the extremely high 1989 solar maximum crucial for understanding the evolution of the Martian atmosphere. Our escape rate analysis is expanded to include all usable heavy ion measurements (O+, O++, O2+) from the circular orbits of Phobos 2. We used an empirical model for the ion distribution function in the Martian tail, based on Mars Express data, to reexamine the Phobos 2 data. The newly calculated fluxes in the Martian tail were also recalibrated against IMP-8 measurements of the solar wind and Phobos 2-TAUS ion measurements in the tail. Heavy ion flux measurements from 18 circular equatorial orbits around Mars have were bin-averaged to a grid, using the MSE (electric field) frame of reference and data from the MAGMA magnetometer. The heavy ion flux grid reveals a disturbed Martian magnetosphere and is integrated to yield a total planetary heavy ion escape rate of 2.2 × 1025 s-1 from Mars for the 1989 solar maximum.

Ramstad, Robin; Futaana, Yoshifumi; Barabash, Stas; Nilsson, Hans; Fedorov, Andrei; del Campo Barraza, Sergio Martin; Lundin, Rickard; Schwingenschuh, Konrad

2013-04-01

368

Revisiting the relationship between adaptive smoothing and anisotropic diffusion with modified filters.  

PubMed

Anisotropic diffusion has been known to be closely related to adaptive smoothing and discretized in a similar manner. This paper revisits a fundamental relationship between two approaches. It is shown that adaptive smoothing and anisotropic diffusion have different theoretical backgrounds by exploring their characteristics with the perspective of normalization, evolution step size, and energy flow. Based on this principle, adaptive smoothing is derived from a second order partial differential equation (PDE), not a conventional anisotropic diffusion, via the coupling of Fick's law with a generalized continuity equation where a "source" or "sink" exists, which has not been extensively exploited. We show that the source or sink is closely related to the asymmetry of energy flow as well as the normalization term of adaptive smoothing. It enables us to analyze behaviors of adaptive smoothing, such as the maximum principle and stability with a perspective of a PDE. Ultimately, this relationship provides new insights into application-specific filtering algorithm design. By modeling the source or sink in the PDE, we introduce two specific diffusion filters, the robust anisotropic diffusion and the robust coherence enhancing diffusion, as novel instantiations which are more robust against the outliers than the conventional filters. PMID:23193236

Ham, Bumsub; Min, Dongbo; Sohn, Kwanghoon

2012-11-10

369

"Toward a Clearer Definition of Confounding" Revisited With Directed Acyclic Graphs  

PubMed Central

In a 1993 paper (Am J Epidemiol. 1993;137(1):1–8), Weinberg considered whether a variable that is associated with the outcome and is affected by exposure but is not an intermediate variable between exposure and outcome should be considered a confounder in etiologic studies. As an example, she examined the common practice of adjusting for history of spontaneous abortion when estimating the effect of an exposure on the risk of spontaneous abortion. She showed algebraically that such an adjustment could substantially bias the results even though history of spontaneous abortion would meet some definitions of a confounder. Directed acyclic graphs (DAGs) were introduced into epidemiology several years later as a tool with which to identify confounders. The authors now revisit Weinberg's paper using DAGs to represent scenarios that arise from her original assumptions. DAG theory is consistent with Weinberg's finding that adjusting for history of spontaneous abortion introduces bias in her original scenario. In the authors' examples, treating history of spontaneous abortion as a confounder introduces bias if it is a descendant of the exposure and is associated with the outcome conditional on exposure or is a child of a collider on a relevant undirected path. Thoughtful DAG analyses require clear research questions but are easily modified for examining different causal assumptions that may affect confounder assessment.

Howards, Penelope P.; Schisterman, Enrique F.; Poole, Charles; Kaufman, Jay S.; Weinberg, Clarice R.

2012-01-01

370

Revisiting a fundamental test of the disc instability model for X-ray binaries  

NASA Astrophysics Data System (ADS)

We revisit a core prediction of the disc instability model (DIM) applied to X-ray binaries. The model predicts the existence of a critical mass-transfer rate, which depends on disc size, separating transient and persistent systems. We therefore selected a sample of 52 persistent and transient neutron star and black hole X-ray binaries and verified if the observed persistent (transient) systems do lie in the appropriate stable (unstable) region of parameter space predicted by the model. We find that, despite the significant uncertainties inherent to these kinds of studies, the data are in very good agreement with the theoretical expectations. We then discuss some individual cases that do not clearly fit into this main conclusion. Finally, we introduce the transientness parameter as a measure of the activity of a source and show a clear trend of the average outburst recurrence time to decrease with transientness in agreement with the DIM predictions. We therefore conclude that, despite difficulties in reproducing the complex details of the light curves, the DIM succeeds in explaining the global behaviour of X-ray binaries averaged over a long enough period of time.

Coriat, M.; Fender, R. P.; Dubus, G.

2012-08-01

371

Circles Revisited.  

ERIC Educational Resources Information Center

Discusses six examples that discover supplementary geometry theorems by using three elementary theorems about the relationships between angles and intercepted arcs in circles. Topics in the examples include angles formed by parallel lines and the sum of the interior angles of triangles, convex quadrilaterals, star polygons, and hexagons. (MDH)

Burke, Maurice

1992-01-01

372

Osteomalacia revisited  

Microsoft Academic Search

The aim of this study was to analyse the clinical manifestations and the most frequent causes of osteomalacia (OM) in a group\\u000a of 28 patients diagnosed with this disorder during a 20-year period. OM was diagnosed by bone biopsy and\\/or by Bingham and\\u000a Fitzpatrick criteria (two of the following: low calcium, low phosphate, elevated total alkaline phosphatase [total AP] or

Laia Gifre; Pilar Peris; Ana Monegal; Maria Jesús Martinez de Osaba; Luisa Alvarez; Núria Guañabens

2011-01-01

373

PACER Revisited.  

National Technical Information Service (NTIS)

This paper discusses a modified version of the PACER concept for power and nuclear material production. In the PACER concept, a 20-kt peaceful nuclear explosion is contained in a cavity about 200 m in diameter, filled with 200 atom of 500 degree C steam. ...

R. W. Moir

1988-01-01

374

PACER Revisited.  

National Technical Information Service (NTIS)

This paper discusses a modified version of the PACER concept for power and nuclear material production, which changes the working fluid in the cavity from steam to the molten salt, LiF + BeF sub 2 . In the PACER concept, a 20-kt peaceful nuclear explosion...

R. W. Moir

1988-01-01

375

Leukemia revisited  

SciTech Connect

Selected features of the historical development of our knowledge of leukemia are discussed. The use of different methodologies for study of the nature of leukemic cell proliferation are analyzed. The differences between older cell kinetic data using tritiated thymidine and autoradiography and the newer cell culture methods are more apparent than real. It is suggested that tritiated thymidine and extracorporeal irradiation of the blood may be useful for therapeutic agents that have not been given an adequate trial. Radiation leukemogenesis presents an opportunity for study of the nature of leukemogenesis that has not been exploited adequately.

Cronkite, E P

1980-01-01

376

Einstein Revisited  

ERIC Educational Resources Information Center

|A brief description on the work and life of the great physicist scientist Albert Einstein is presented. The photoelectric paper written by him in 1905 led him to the study of fluctuations in the energy density of radiation and from there to the incomplete nature of the equipartition theorem of classical mechanics, which failed to account for…

Fine, Leonard

2005-01-01

377

Control revisited  

Microsoft Academic Search

Some personal recollections of automatic control before 1947. My first contact with a process control system occurred when I went to work in the Physics Laboratory of Dow Chemical Company, Midland, Michigan, in the summer of 1936. This laboratory was then headed by Dr. John Grebe. I was assigned as an operator of a very small pilot plant which was

Nathaniel B. Nichols

1977-01-01

378

Brezinaite Revisited  

NASA Astrophysics Data System (ADS)

Brezinaite Data: Idealized formula: (Cr^2+Cr^3+)(sub)3S(sub)4, metal: sulphur ratio=0.76 - 0.79, structure: defect NiAs-type, symmetry: monoclinic I 2/m, Beta = 91 degrees 32'. As part of a research program in Copenhagen and at the Smithsonian Institution involving sulphides in selected irons, the mineral brezinaite was, quite surprisingly, found to be present in several of the sections studied. Brezinaite is a rare meteoritic sulphide, previously only reported in two Anom. irons; Tucson [1] and New Baltimore [2] , a list that can now be extended to include, as a minimum, the following meteorites: Type IIIA; Costilla Peak, Kalkaska and Murfreesboro. Type IVA; Jamestown, La Grange and Western Arkansas. Anom. or type IIIF; Saint Genevieve County. A thin section examination by reflected light alone will not always be enough to identify the mineral with sufficient accuracy, and it is, therefore, only meteorites in which brezinaite has been confirmed by microprobe analysis that are mentioned above. With the exception of Tucson, where brezinaite is frequently found as anhedral grains contiguous to silicate inclusions, its typical occurrence is either in or along sub-boundaries of the kamacite bands, or occasionally within comb- structured plessite fields. Brezinaite appears most commonly as minute (5-200 micrometers) anhedral-subhedral greyish colored grains, occasionally with a partial rim of schreibersite (eg., Murfreesboro), that occur freely scattered throughout the metal matrix. With the notable exception of troilite aggregates, in which brezinaite does not occur, its appearance and occurrence coincide with the common mineral daubreelite (VH~400 and R% = 37- 40). The difficulty in distinguishing between these two minerals has been a source of confusion. The present study shows that the two minerals both occur as isolated grains and in the immediate vicinity of each other. The intimate relationship between the two minerals is especially clear in Costilla Peak where one (180/120 micrometer) grain was found to consist of alternating thin lamellae of daubreelite and brezinaite. Such lamellae cannot, however, be distinguished in reflected light! Brezinaite does, however, have several distinctive features that are of diagnostic value in separating it from daubreelite. Brezinaite possesses a high degree of anisotropy that may vary from barely detectable to very pronounced, due to differing optical orientations. In general, brezinaite is not abundant in any one thin section, thus unfavorably oriented grains can be mistaken for daubreelite. More characteristic is the quite frequent display of polysynthetic twins in brezinaite, eg., Tucson, Western Arkansas, and to a lesser degree Jamestown. The twinned character is most commonly seen as two sets of parallel lamallae, almost at right angles to one another. Occasionally a third set of more irregular twins can be seen to intersect the two former at an oblique angle, as shown in Fig. 1. References: [1] Bunch T. E. and Fuchs L. H. (1969) Am. Miner., 54, 1509-1518. [2] Buchwald V. F. (1975) I-III, University of California, 1-1418. Fig. 1, which appears here in the hard copy, shows twinned brezinaite bordering a silicate inclusion in the Tucson meteorite. Crossed nicols, X 400. In a future study it is planned to cross-examine the Fe-Cr sulphides with a view to improve our understanding of iron meteorites at moderate to low temperatures.

Davis, D. E.

1993-07-01

379

Neologisms Revisited  

Microsoft Academic Search

Oscar Gray, you are a great student of Jimmy's [Fleming James] and since you and I are not the last, but among the last, of his students, it pleased me particularly that you remembered him. Thank you. I also want to thank all my other friends who took the time to come here today, and most especially this University, which

Guido Calabresi

2005-01-01

380

Endosymbiosis Revisited.  

ERIC Educational Resources Information Center

|Presents insights into the endosymbiotic theory based on a re-examination of evidence from investigations into the archaebacteria and other strange organisms inhabiting the hindguts of wood-eating insects. Examines the mechanism of evolutionary change and the speed with which it occurs. (RT)|

Tribe, Michael A.

1988-01-01

381

Endosymbiosis revisited  

Microsoft Academic Search

The mechanism of evolutionary change and the speed with which it occurs is of fundamental interest to biologists. It is generally agreed that cytosis and endosymbiosis have had a profound influence upon the evolution of eukaryotic cells. The endosymbiotic theory in particular is re-examined in the light of more recent evidence from investigations into the archaebacteria and other strange organisms

Michael A. Tribe

1988-01-01

382

Speechreading Revisited  

ERIC Educational Resources Information Center

Although speechreading has always served an important role in the communication of deaf people, educational interest in speechreading has decreased in recent decades. This paper reviews speechreading in terms of speech processing, neural activity and literacy, and suggests that it has an important role in intervention programmes for all deaf…

Woll, Bencie

2012-01-01

383

PACER revisited  

NASA Astrophysics Data System (ADS)

This paper discusses a modified version of the PACER concept for power and nuclear material production. In the PACER concept, a 20-kt peaceful nuclear explosion is contained in a cavity about 200 m in diameter, filled with 200 atom of 500 C steam. Energy from the explosion is used to produce power, and the neutrons are used to produce materials such as U-233. The present idea is to modify the PACER concept in three ways to improve the practicality, predictability, and safety of power production from this technology and thus improve public acceptance of this power source. These improvements are: (1) line the cavity with steel; (2) replace the steam with molten salt, LiF + BeF2; and (3) reduce the explosive yield to about 2 kt. PACER is the only fusion power concept where the underlying technology of the power source itself is proven and in hand today. The molten-salt shock-suppression and heat transport system and the durability of the underground cavity need demonstration.

Moir, Ralph W.

1988-11-01

384

Filaggrin - revisited.  

PubMed

Profilaggrin (proFLG) and its processing products are critical to the health and appearance of skin. The recent identification of loss-of-function filaggrin (FLG) mutations as a predisposing factor in ichthyosis vulgaris and atopic dermatitis has lead to a resurgent interest in this enigmatic protein. Here, we review the literature on the structure and many functions of proFLG, from its role as a filament-aggregating protein and a source of natural moisturizing factor (NMF), to the more recent discoveries of its role in epidermal barrier formation and its more speculative functions as an antimicrobial and sunscreen. Finally, we discuss the relationship of proFLG with dry skin, the influence of moisturizers on NMF generation and speculate on next generation of FLG research. PMID:23517450

Harding, C R; Aho, S; Bosko, C A

2013-04-18

385

Countertransference revisited.  

PubMed

A female patient of mine recounts her week. I listen with interest, waiting for her to arrive at particular conclusions. She has suffered a great deal and still does, but prefers not to dwell on it. My interest turns into patience as she continues to talk but circumvents her discontent. She is adroit at avoidance, but easily offended when I point such things out. "I'd better wait" I think. I grow more aware that I must encourage her digressions. I feel frustrated. Getting further and further away, she skirts the issue with supple grace, then strays off into tangentiality. I forget her point and lose my focus, then get down on myself. The opportunity is soon gone. I glance at the clock as her monologue drones on into banality. I grow more uninterested and distant. There is a subtle irritation to her voice; a whiney indecisive ring begins to pervade my consciousness. I home in on her mouth with aversion, watching apprehensively as this disgusting hole flaps tirelessly but says nothing. It looks carnivorous, voracious. Now she is unattractive, something I have noticed before. I forget who my next patient is. I think about the meal I will prepare for my wife this evening, then glance at the time once more. Then I am struck: Why am I looking at the clock? So soon? The session has just begun. I catch myself. What is going on in me, between us? I am detached, but why? Is she too feeling unattuned, disconnected? I am failing my patient. What is her experience of me? I lamentingly confess that I do not feel I have been listening to her, and wonder what has gone wrong between us. I ask her if she has noticed. We talk about our feelings, our impact on one another, why we had lost our sense of connection, what it means to us. I instantly feel more involved, rejuvenated, and she continues, this time with me present. Her mouth is no longer odious, but sincere and articulate. She is attractive and tender; I suddenly feel empathy and warmth toward her. We are now very close. I am moved. Time flies, the session is soon over; we do not want it to end. PMID:15491945

Mills, Jon

2004-08-01

386

Revisiting dandruff.  

PubMed

Dandruff is a common scalp disorder affecting almost half of the postpubertal population of any ethnicity and both genders. It may, however, represent a stubborn esthetical disturbance often source of pruritus. Skin biocenosis, in particular the Malassezia spp. flora, plays a key aetiologic role, in combination with the unusual capacity of some corneocytes to be coated by these yeasts. Substantial evidence indicates that keratinocytes play an active role in the generation and expression of immunopathological reactions. This is probably the case in dandruff. Upon stimulation of a critical colonization of corneocytes by Malassezia yeasts, the release of pro-inflammatory mediators is increased. This could lead to the subclinical microinflammation present in dandruff. In seborrheic dermatitis, local deposits of immunoglobulins and the release of lymphokines are responsible for the recruitment and local activation of leukocytes leading to the eventual amplification of the inflammatory reaction. Some ancillary non-microbial causes of dandruff may operate through physical or chemical irritants. Many methods have been described for rating dandruff. Our favourite tools are clinical examination and squamometry. Dandruff can precipitate telogen effluvium and exacerbate androgenic alopecia. Antidandruff formulations exhibiting some direct or indirect anti-inflammatory activity can improve both dandruff and its subsequent hair cycle disturbance. PMID:18489295

Piérard-Franchimont, C; Xhauflaire-Uhoda, E; Piérard, G E

2006-10-01

387

Visibles Revisited  

ERIC Educational Resources Information Center

Within the set of points in the plane with integer coordinates, one point is said to be visible from another if no other point in the set lies between them. This study of visibility draws in topics from a wide variety of mathematical areas, including geometry, number theory, probability, and combinatorics.

Bridger, Mark; Zelevinsky, Andrei

2005-01-01

388

Siphons, Revisited  

ERIC Educational Resources Information Center

|The siphon is a very useful example of early technology, the operation of which has long been well understood. A recent article makes the claim that established beliefs regarding this device are incorrect and proposes a "chain model" in which intermolecular forces within the fluid play a large role while atmospheric pressure does not. We have…

Richert, Alex; Binder, P. -M.

2011-01-01

389

Speechreading Revisited  

ERIC Educational Resources Information Center

|Although speechreading has always served an important role in the communication of deaf people, educational interest in speechreading has decreased in recent decades. This paper reviews speechreading in terms of speech processing, neural activity and literacy, and suggests that it has an important role in intervention programmes for all deaf…

Woll, Bencie

2012-01-01

390

Fixpoints Revisited  

Microsoft Academic Search

This is an attempt to update some old results by the author on least fixpoints of endofunctors of categories. It is now assumed that the categories in question are cartesian or bicartesian closed and that the functors can be expressed as polynomials. Moreover, in place of completeness one now requires only a weak kind of product in addition to joint

Joachim Lambek

1989-01-01

391

Excellence Revisited.  

ERIC Educational Resources Information Center

|Excellence in education of gifted children is the focus of this journal theme issue. Two articles are featured: (1) "Making Connections for the At-Risk Gifted Child" by Mary Kay Finholt and Kathy Peckron, describing an exemplary support system developed for at-risk gifted students in the Rockwood School District in Missouri, which provides…

Silverman, Linda Kreger, Ed.

1993-01-01

392

Asparaginase revisited.  

PubMed

Asparaginase is one of the main drugs used to treat acute lymphoblastic leukemia and certain non-Hodgkin lymphomas. The drug is a bacterial product, and this results in differences in activity, efficacy, and side effects among the various marketed products. Native products originate from either Escherichia coli or Erwinia chrysanthemi. Currently a new product, PEG-asparaginase, is on the market. Recombinant asparaginases will be entering the market in a few years, and development of the incorporation of asparaginase in erythrocytes is progressing. This article reviews the available data on the various asparaginases and current developments. Differences between the various preparations are discussed in relation to pharmacokinetics, i.e. the short half-life of Erwinia preparations and prolonged activity of PEG-asparaginase. Uncertainties in relation to antibody formation and batch related differences of the newer products are discussed. The adverse effects related to origin of a product, mode of action, and antibody formation are also discussed. PMID:21281233

van den Berg, Henk

2011-02-01

393

Entry, revisited  

Microsoft Academic Search

How can an individual reenter a society of which he has never truly been a member? What does the PRI miss in assuming that\\u000a the individual offender is the only potentially successful site for intervention? Drawing on his personal experience as an\\u000a educator in prisons, public schools, and the PRI, the author argues that education in the PRI can best

Daniel Stageman

2010-01-01

394

Leadership Revisited.  

National Technical Information Service (NTIS)

This paper, prepared for delivery at the symposium commemorating the 50th anniversary of the inception of the Hawthorne Studies, reviews a variety of approaches to the investigation of leadership in organizations. Concepts of leadership as a general trait...

V. H. Vroom

1974-01-01

395

Unification Revisited  

Microsoft Academic Search

In the literature unification is often treated as a simple and straightforward matter, even though it is recognized as a deep and fundamental concept. However when a thorough presentation is attempted, it is then realized that the matter is fairly subtle and treacherous. For instance the notion of most general unifier and its property of being unique up to renaming

Jean-louis Lassez; Michael J. Maher; Kim Marriott

1986-01-01

396

Polypseudologarithms revisited  

NASA Astrophysics Data System (ADS)

Lee, in a series of papers, described a unified formulation of the statistical thermodynamics of ideal quantum gases in terms of the polylogarithm functions, Li(z). It is aimed here to investigate the functions Li(z), for s=0,-1,-2,…, which are, following Lee, referred to as the polypseudologarithms (or polypseudologs) of order n?-s. Various known results regarding polypseudologs, mainly obtained in widely differing contexts and currently scattered throughout the literature, have been brought together along with many new results and insights and they all have been proved in a simple and unified manner. In addition, a new general explicit closed-form formula for these functions involving the Carlitz-Scoville higher tangent numbers has been established.

Cvijovi?, Djurdje

2010-04-01

397

Oligometastases revisited.  

PubMed

We previously proposed a clinical state of metastasis termed 'oligometastases' that refers to restricted tumor metastatic capacity. The implication of this concept is that local cancer treatments are curative in a proportion of patients with metastases. Here we review clinical and laboratory data that support the hypothesis that oligometastasis is a distinct clinical entity. Investigations of the prevalence, mechanism of occurrence, and position in the metastatic cascade, as well as the determination of molecular markers to distinguish oligometastatic from polymetastatic disease, are ongoing. PMID:21423255

Weichselbaum, Ralph R; Hellman, Samuel

2011-03-22

398

Panspermia revisited  

NASA Astrophysics Data System (ADS)

"Panspermia", coined by S. Arrhenius in 1903, suggests that microscopic forms of life, e.g., bacterial spores, can be dispersed in space by the radiation pressure from the Sun thereby seeding life from one planet to another or even beyond our Solar System. Being ignored for almost the rest of the century, the scenario of interplanetary transfer of life has received increased support from recent discoveries, such as the detection of Martian meteorites and the high resistance of microorganisms to outer space conditions. With the aid of space technology and adequate laboratory devices the following decisive step required for viable transfer from one planet to another have been tested: (i) the escape process, i.e. impact ejection into space; (ii) the journey through space over extended periods of time; and (iii) the landing process, i.e. non-destructive deposition of the biological material on another planet. In systematic shock recovery experiments within a pressure range observed in Martian meteorites (5-50 GPa) a vital launch window of 5-40 GPa has been determined for spores of Bacillus subtilis and the lichen Xanthoria elegans, whereas this window was restricted to 5-10 GPa for the endolithic cyanobaterium Chroococcidiopsis. Traveling through space implies exposure to high vacuum, an intense radiation regime of cosmic and solar origin and high temperature fluctuations. In several space experiments the biological efficiency of these different space parameters has been tested: extraterrestrial solar UV radiation has exerted the most deleterious effects to viruses, as well as to bacterial and fungal spores; however shielding against this intense insolation resulted in 70 % survival of B. subtilis spores after spending 6 years in outer space. Lichens survived 2 weeks in space, even without any shielding. The entry process of microorganisms has been recently tested in the STONE facility attached to the heat shield of a reentry capsule. The data support the scenario of "Lithopanspermia", which assumes that impact-expelled rocks serve as interplanetary transfer vehicles for microorganisms colonizing those rocks. Literature: St¨ffler D, Horneck G, Ott S, Hornemann, U, Cockell CS, Moeller R, Meyer C, de Vera J-P, o Fritz J, Artemieva NA,.Experimental evidence for the potential impact ejection of viable microorganisms from Mars and Mars-like planets (2007) Icarus, 186, 585-588. Sancho, L.G., de la Torre, R., Horneck, G., Ascaso, C., de los Rios, A., Pintado, A., Wierzchos, J. and Schuster, M. (2007) Lichens survive in space: Results from the 2005 LICHENS experiment. Astrobiology, 7, 443-454. Mileikowsky C, Cucinotta F, Wilson J W, Gladman B, Horneck G, Lindegren L, Melosh J, Rickman H, Valtonen M, Zheng J Q (2000) Natural transfer of viable microbes In space, Part 1: From Mars to Earth and Earth to Mars, Icarus, 145, 391-427. Nicholson WL, Munakata N, Horneck G, Melosh HJ, and Setlow P (2000) Resistance of Bacillus endospores to extreme terrestrial and extraterrestrial environments, Microb. Mol. Biol. Rev. 64, 548-572.

Horneck, Gerda

399

Totalitarianism Revisited  

Microsoft Academic Search

The terrorist attacks of September 11, 2001, and the debate over the American war in Iraq, revived talk of totalitarianism among liberals and leftists thinking about radical Islamists and Middle East dictatorships. With varying degrees of enthusiasm, respected former dissidents such as Vaclav Havel and Adam Michnik and distinguished intellectuals in Europe and America such as Paul Berman, André Glucksmann,

Anson Rabinbach

2006-01-01

400

Balloons Revisited  

ERIC Educational Resources Information Center

|Whilst everyone is familiar with the process of blowing up a balloon, few of us have gone further to quantify the actual pressures involved at different stages in the inflation process. This paper seeks to describe experiments to fill some of those gaps and examine some of the apparently anomalous behaviour of connected balloons. (Contains 12…

Jeskova, Z.; Featonby, D.; Fekova, V.

2012-01-01

401

"Brown" Revisited.  

ERIC Educational Resources Information Center

The 1954 "Brown" decision and its 1955 enforcement decree were merely keystone events in a decade-long effort to replace South's elaborate system of legal segregation with type of de facto segregation found in northern, western, and midwestern cities resulting from well-defined racial barriers between neighborhoods. The traditional histories have…

White, Forrest R.

1994-01-01

402

Coadaptation revisited  

SciTech Connect

During the four decades or more since Dobzhansky introduced the term 'coadaptation' to refer to the commonly observed selective superiority of inversion heterozygotes in populations of Drosophila pseudoobscura, the definition of the term has evolved, as have views concerning the rapidity with which coadaptation might occur. Indeed, the paucity of demonstrated instances of linkage disequilibrium in natural populations has led many to dismiss coadaptation as a factor in evolutionary change. The present article reviews the reasons why coadaptation (and the equivalent expression, 'integration of gene pools') was proposed as a phenomenon occurring in local (or experimental) populations, offers supporting data obtained through a reanalysis of data on irradiated populations of D. melanogaster, and concludes that sound evidence supports coadaptation as a factor in the genetic change of populations.65 references.

Wallace, B. (Virginia Polytechnic Institute and State Univ., Blacksburg (USA))

1991-03-01

403

Romania Revisited.  

National Technical Information Service (NTIS)

The report discusses current research in some marine facilities in Romania and describes facilities. In effect, it updates the report 'Marine Sciences in Romania' ONRL 7-67 (AD-808 471). It also contains a bibliography of publications by Romanian marine b...

J. D. Costlow

1970-01-01

404

Arhinia revisited.  

PubMed

Arhinia is a rare anomaly in which a total absence of the nose and parts of the olfactory system occurs. It is frequently associated with various multiple central nervous system (CNS) and somatic anomalies of different degrees of severity, with high mortality rate. Twelve cases that have been reported in the literature are analyzed according to multiple criteria. The anomalies that have been found to be associated with arhinia are: lack of olfactory bulbs and nerves, missing paranasal sinuses, high arched or cleft palate, various eye anomalies, low set ears - all in a very high incidence. Various degrees of CNS malformations have been found in part of the cases. Somatic anomalies have been reported in 50% of the cases. In two cases chromosome 9 anomalies have been reported. A classification is suggested in which arhinia is classified into arhinia (total absence of the nose and rhinencephalon) and partial arhinia (partial absence of the nose), each may or may not be associated with other malformations (facial, CNS and somatic). PMID:3324281

Cohen, D; Goitein, K J

1987-12-01

405

Normal cerebral asymmetry in familial and non-familial schizophrenic probands and their unaffected relatives  

Microsoft Academic Search

Loss of normal fronto-occipital cerebral asymmetry has been reported in patients with schizophrenia and also in their well relatives from multiply affected families, suggesting a relationship with susceptibility genes. We sought to confirm this relationship in a family study of patients with schizophrenia and their unaffected relatives of presumed differing genetic risk. MRI scans were carried out on 25 probands

Ben Chapple; Anton Grech; Pak Sham; Timothea Toulopoulou; Muriel Walshe; Katja Schulze; Kevin Morgan; Robin M. Murray; Colm McDonald

2004-01-01

406

Beyond the Arcuate Fasciculus: Consensus and Controversy in the Connectional Anatomy of Language  

ERIC Educational Resources Information Center

|The growing consensus that language is distributed into large-scale cortical and subcortical networks has brought with it an increasing focus on the connectional anatomy of language, or how particular fibre pathways connect regions within the language network. Understanding connectivity of the language network could provide critical insights into…

Dick, Anthony Steven; Tremblay, Pascale

2012-01-01

407

White Matter Microstructure in Superior Longitudinal Fasciculus Associated with Spatial Working Memory Performance in Children  

ERIC Educational Resources Information Center

|During childhood and adolescence, ongoing white matter maturation in the fronto-parietal cortices and connecting fiber tracts is measurable with diffusion-weighted imaging. Important questions remain, however, about the links between these changes and developing cognitive functions. Spatial working memory (SWM) performance improves significantly…

Vestergaard, Martin; Madsen, Kathrine Skak; Baare, William F. C.; Skimminge, Arnold; Ejersbo, Lisser Rye; Ramsoy, Thomas Z.; Gerlach, Christian; Akeson, Per; Paulson, Olaf B.; Jernigan, Terry L.

2011-01-01

408

White Matter Microstructure in Superior Longitudinal Fasciculus Associated with Spatial Working Memory Performance in Children  

ERIC Educational Resources Information Center

During childhood and adolescence, ongoing white matter maturation in the fronto-parietal cortices and connecting fiber tracts is measurable with diffusion-weighted imaging. Important questions remain, however, about the links between these changes and developing cognitive functions. Spatial working memory (SWM) performance improves significantly…

Vestergaard, Martin; Madsen, Kathrine Skak; Baare, William F. C.; Skimminge, Arnold; Ejersbo, Lisser Rye; Ramsoy, Thomas Z.; Gerlach, Christian; Akeson, Per; Paulson, Olaf B.; Jernigan, Terry L.

2011-01-01

409

Cingulate fasciculus integrity disruption in schizophrenia: a magnetic resonance diffusion tensor imaging study  

Microsoft Academic Search

BackgroundEvidence suggests that a disruption in limbic system network integrity and, in particular, the cingulate gyrus (CG), may play a role in the pathophysiology of schizophrenia; however, the cingulum bundle (CB), the white matter tract furnishing both input and output to CG, and the most prominent white matter fiber tract in the limbic system, has not been evaluated in schizophrenia

Marek Kubicki; Carl-Fredrik Westin; Paul G. Nestor; Cynthia G. Wible; Melissa Frumin; Stephan E. Maier; Ron Kikinis; Ferenc A. Jolesz; Robert W. McCarley; Martha E. Shenton

2003-01-01

410

Theoretical Investigation of the Enzymatic Phosphoryl Transfer of ?-phosphoglucomutase: Revisiting Both Steps of the Catalytic Cycle  

SciTech Connect

Enzyme catalyzed phosphate transfer is a part of almost all metabolic processes. Such reactions are of central importance for the energy balance in all organisms and play important roles in cellular control at all levels. Mutases transfer a phosphoryl group while nucleases cleave the phosphodiester linkages between two nucleotides. The subject of our present study is the Lactococcus lactis ?-phosphoglucomutase (?-PGM), which effectively catalyzes the interconversion of ?-D-glucose-1-phosphate (?-G1P) to ?- D-glucose-6-phosphate (?-G6P) and vice versa via stabile intermediate ?-D-glucose-1,6-(bis)phosphate (?-G1,6diP) in the presence of Mg2+. In this paper we revisited the reaction mechanism of the phosphoryl transfer starting from the bisphosphate ?-G1,6diP in both directions (toward ?-G1P and ?-G6P) combining docking techniques and QM/MM theoretical method at the DFT/PBE0 level of theory. In addition we performed NEB (nudged elastic band) and free energy calculations to optimize the path and to identify the transition states and the energies involved in the catalytic cycle. Our calculations reveal that both steps proceed via dissociative pentacoordinated phosphorane, which is not a stabile intermediate but rather a transition state. In addition to the Mg2+ ion, Ser114 and Lys145 also play important roles in stabilizing the large negative charge on the phosphate through strong coordination with the phosphate oxygens and guiding the phosphate group throughout the catalytic process. The calculated energy barrier of the reaction for the ?-G1P to ?-G1,6diP step is only slightly higher than for the ?-G1,6diP to ?-G6P step (16.10 kcal mol-1 versus 15.10 kcal mol-1) and is in excellent agreement with experimental findings (14.65 kcal mol-1).

Elsasser, Brigitta M.; Dohmeier-Fischer, Silvia; Fels, Gregor

2012-07-12

411

The use of self-expanding stents in coronary bifurcations and beyond: a paradigm revisited.  

PubMed

Conventional tubular balloon expandable (BE) stent designs are poorly suited to coronary bifurcations, yielding highly variable results. For this reason, intense interest remains and industry development continues for dedicated bifurcation coronary stents to make treatment of such lesions more straightforward. Innovative designs have emerged, some balloon expandable, but also self-expandable, based on the premise that nitinol based designs may conform more favourably than other metals to non-tubular vascular structures such as bifurcations. Through discussion of one of the early implantations of the first of these new age self-expanding designs, the Devax coronary bifurcation system, we outline the state-of-the-art use of self-expanding designs in percutaneous intervention to coronary bifurcations, and revisit an old paradigm with contemporary applications. The Devax system was the first of a new generation of self-expanding coronary stents after a more than 15 year lull in their development and was also the first dedicated drug eluting stent (DES) for bifurcations. It was first used in man in 2003. Other self-expanding designs have followed and shown promise in this setting, including Stentys and the Capella Sideguard. New indications have also emerged, including small vessels, addressed by the Cardiomind Sparrow and soft, unstable lesions, treated by the vProtect luminal shield. Of note, all the novel devices presented have a relative paucity of clinical data with no randomised clinical trials to date, but--if the contemporary results continue to be favourable--their indications may become more widespread in the future of coronary intervention. PMID:19378690

Jilaihawi, Hasan; Farah, Bruno; Laborde, Jean-Claude

2009-03-01

412

Trends in ostracod distribution and water chemistry in subarctic Canada: Churchill (Manitoba) lakes and ponds revisited  

NASA Astrophysics Data System (ADS)

Ecosystems change in response to factors such as climate variability, invasions, and natural hazards over a short period of time (IPCC 2007). The individual organism has to react to complete its life cycle and eventually to reproduce successfully. Under extreme conditions the survival of the total population depends thoroughly on the genetic diversity/potential and thus the ability to expand its biogeographical range or to run extinct. The knowledge of the specific plasticity in time is essential to interpret signals of biological proxies in palaeo records. We investigated 13 lakes/ponds in the surrounding of the Churchill Northern Studies Centre (CNSC; 58° 43.989'N, 93° 49.219'W), Churchill, Canada in 1997. 9 years later we revisited the same localities in 2006. In addition, faunistic data of microcrustaceans in the local study area is available from the late 80's (Havel et al 1990 a, b). and further instrumental climate records from Churchill (Manitoba, Canada) are daily filed since 1943 by Environment Canada. Thus we were able to pinpoint local warming trends and changes in the water chemistry from our short term records in the subarctic study area. The microcrustacean fauna change consecutively. e.g., freshwater ostracods adopted to short open water periods during the summer, strong variations of water temperatures in the shallow waters and mostly low ionic contents of the host waters are not present in the current record. References: Havel, J.E., Hebert, P.D.N. and Delorme, L.D., 1990a. Genetics of sexual Ostracoda from a low Arctic site. Journal of Evolutionary Biology, 3: 65-84. Havel, J.E., Hebert, P.D.N. and Delorme, L.D., 1990b. Genotypic diversity of asexual Ostracoda from a low Arctic site. Journal of Evolutionary Biology, 3: 391-410.

Viehberg, F. A.; Côté, G.; Pienitz, R.

2009-04-01

413

Heparin and cancer revisited: Mechanistic connections involving platelets, P-selectin, carcinoma mucins, and tumor metastasis  

NASA Astrophysics Data System (ADS)

Independent studies indicate that expression of sialylated fucosylated mucins by human carcinomas portends a poor prognosis because of enhanced metastatic spread of tumor cells, that carcinoma metastasis in mice is facilitated by formation of tumor cell complexes with blood platelets, and that metastasis can be attenuated by a background of P-selectin deficiency or by treatment with heparin. The effects of heparin are not primarily due to its anticoagulant action. Other explanations have been suggested but not proven. Here, we bring together all these unexplained and seemingly disparate observations, showing that heparin treatment attenuates tumor metastasis in mice by inhibiting P-selectin-mediated interactions of platelets with carcinoma cell-surface mucin ligands. Selective removal of tumor mucin P-selectin ligands, a single heparin dose, or a background of P-selectin deficiency each reduces tumor cell-platelet interactions in vitro and in vivo. Although each of these maneuvers reduced the in vivo interactions for only a few hours, all markedly reduce long-term organ colonization by tumor cells. Three-dimensional reconstructions by using volume-rendering software show that each situation interferes with formation of the platelet "cloak" around tumor cells while permitting an increased interaction of monocytes (macrophage precursors) with the malignant cells. Finally, we show that human P-selectin is even more sensitive to heparin than mouse P-selectin, giving significant inhibition at concentrations that are in the clinically acceptable range. We suggest that heparin therapy for metastasis prevention in humans be revisited, with these mechanistic paradigms in mind.

Borsig, Lubor; Wong, Richard; Feramisco, James; Nadeau, David R.; Varki, Nissi M.; Varki, Ajit

2001-03-01

414

Revisiting the Polyoxometalate-Based Late-Transition-Metal-Oxo Complexes: The “Oxo Wall” Stands  

SciTech Connect

Terminal oxo complexes of the late transition metals Pt, Pd, and Au have been reported by us in Science and Journal of the American Chemical Society. Despite thoroughness in characterizing these complexes (multiple independent structural methods and up to 17 analytical methods in one case), we have continued to study these structures. Initial work on these systems was motivated by structural data from X-ray crystallography and neutron diffraction and 17O and 31P NMR signatures which all indicated differences from all previously published compounds. With significant new data, we now revisit these studies. New X-ray crystal structures of previously reported complexes K14[P2W19O69(OH2)] and “K10Na3[PdIV(O)(OH)WO(OH2)(PW9O34)2]” and a closer examination of these structures are provided. Also presented are the 17O NMR spectrum of an 17O-enriched sample of [PW11O39]7– and a careful combined 31P NMR-titration study of the previously reported “K7H2[Au(O)(OH2)P2W20O70(OH2)2].” These and considerable other data collectively indicate that previously assigned terminal Pt-oxo and Au-oxo complexes are in fact cocrystals of the all-tungsten structural analogues with noble metal cations, while the Pd-oxo complex is a disordered Pd(II)-substituted polyoxometalate. The neutron diffraction data have been re-analyzed, and new refinements are fully consistent with the all-tungsten formulations of the Pt-oxo and Au-oxo polyoxometalate species.

O; Halloran, Kevin P.; Zhao, Chongchao; Ando, Nicole S.; Schultz, Arthur J.; Koetzle, Thomas F.; Piccoli, Paula M. B.; Hedman, Britt; Hodgson, Keith O.; Bobyr, Elena; Kirk, Martin L.; Knottenbelt, Sushilla; Depperman, Ezra C.; Stein, Benjamin: Anderson, Travis M.; Cao, Rui; Geletii, Yurii V.; Hardcastle, Kenneth I.; Musaev, Djamaladdin G.; Neiwert, Wade A.; Fang, Xikui; Morokuma, Keiji; Wu, Shaoxiong; Koegerler, Paul, Hill, Craig L.

2012-06-13

415

The growth of galactic bulges through mergers in ? CDM haloes revisited - I. Present-day properties  

NASA Astrophysics Data System (ADS)

We use the combined data sets of the Millennium I and II cosmological simulations to revisit the impact of mergers in the growth of bulges in central galaxies in the ? cold dark matter (?CDM) scenario. We seed galaxies within the growing CDM haloes using semi-empirical relations to assign stellar and gaseous masses, and an analytic treatment to estimate the transfer of stellar mass to the bulge of the remnant after a galaxy merger. We find that this model roughly reproduces the observed correlation between the bulge-to-total mass (B/T) ratio and stellar mass (M*) in present-day central galaxies as well as their observed demographics, although low-mass B/T < 0.1 (bulgeless) galaxies might be scarce relative to the observed abundance. In our merger-driven scenario, bulges have a composite stellar population made of (i) stars acquired from infalling satellites, (ii) stars transferred from the primary disc due to merger-induced perturbations and (iii) newly formed stars in starbursts triggered by mergers. We find that the first two are the main channels of mass assembly, with the first one being dominant for massive galaxies, creating large bulges with different stellar populations than those of the inner discs, while the second is dominant for intermediate/low-mass galaxies and creates small bulges with similar stellar populations to the inner discs. We associate the dominion of the first (second) channel to classical (pseudo) bulges, and compare the predicted fractions to observations. We emphasize that our treatment does not include other mechanisms of bulge growth such as intrinsic secular processes in the disc or misaligned gas accretion. Interestingly, we find that the evolution of the stellar and gaseous contents of the satellite as it spirals towards the central galaxy is a key ingredient in setting the morphology of the remnant galaxy, and that a good match to the observed bulge demographics occurs when this evolution proceeds closely to that of the central galaxy.

Zavala, Jesus; Avila-Reese, Vladimir; Firmani, Claudio; Boylan-Kolchin, Michael

2012-12-01

416

Heparin and cancer revisited: Mechanistic connections involving platelets, P-selectin, carcinoma mucins, and tumor metastasis  

PubMed Central

Independent studies indicate that expression of sialylated fucosylated mucins by human carcinomas portends a poor prognosis because of enhanced metastatic spread of tumor cells, that carcinoma metastasis in mice is facilitated by formation of tumor cell complexes with blood platelets, and that metastasis can be attenuated by a background of P-selectin deficiency or by treatment with heparin. The effects of heparin are not primarily due to its anticoagulant action. Other explanations have been suggested but not proven. Here, we bring together all these unexplained and seemingly disparate observations, showing that heparin treatment attenuates tumor metastasis in mice by inhibiting P-selectin-mediated interactions of platelets with carcinoma cell-surface mucin ligands. Selective removal of tumor mucin P-selectin ligands, a single heparin dose, or a background of P-selectin deficiency each reduces tumor cell-platelet interactions in vitro and in vivo. Although each of these maneuvers reduced the in vivo interactions for only a few hours, all markedly reduce long-term organ colonization by tumor cells. Three-dimensional reconstructions by using volume-rendering software show that each situation interferes with formation of the platelet “cloak” around tumor cells while permitting an increased interaction of monocytes (macrophage precursors) with the malignant cells. Finally, we show that human P-selectin is even more sensitive to heparin than mouse P-selectin, giving significant inhibition at concentrations that are in the clinically acceptable range. We suggest that heparin therapy for metastasis prevention in humans be revisited, with these mechanistic paradigms in mind.

Borsig, Lubor; Wong, Richard; Feramisco, James; Nadeau, David R.; Varki, Nissi M.; Varki, Ajit

2001-01-01

417

Fractional flow in fractured chalk; a flow and tracer test revisited  

NASA Astrophysics Data System (ADS)

A multi-borehole pumping and tracer test in fractured chalk is revisited and reinterpreted in the light of fractional flow. Pumping test data analyzed using a fractional flow model gives sub-spherical flow dimensions of 2.2-2.4 which are interpreted as due to the partially penetrating nature of the pumped borehole. The fractional flow model offers greater versatility than classical methods for interpreting pumping tests in fractured aquifers but its use has been hampered because the hydraulic parameters derived are hard to interpret. A method is developed to convert apparent transmissivity and storativity (L4-n/T and S2-n) to conventional transmissivity and storativity (L2/T and dimensionless) for the case where flow dimension, 2 < n < 3. These parameters may then be used in further applications, facilitating application of the fractional flow model. In the case illustrated, improved fits to drawdown data are obtained and the resultant transmissivities and storativities are found to be lower by 30% and an order of magnitude respectively, than estimates from classical methods. The revised hydraulic parameters are used in a reinterpretation of a tracer test using an analytical dual porosity model of solute transport incorporating matrix diffusion and modified for fractional flow. Model results show smaller fracture apertures, spacings and dispersivities than those when 2D flow is assumed. The pumping and tracer test results and modeling presented illustrate the importance of recognizing the potential fractional nature of flow generated by partially penetrating boreholes in fractured aquifers in estimating aquifer properties and interpreting tracer breakthrough curves.

Odling, N. E.; West, L. J.; Hartmann, S.; Kilpatrick, A.

2013-04-01

418

The Origin and Evolution of DQ White Dwarfs: The Carbon Pollution Problem Revisited  

NASA Astrophysics Data System (ADS)

We summarize some of the results we obtained using detailed evolutionary calculations that take into account diffusion and mass loss to revisit the question of the carbon pollution observed in the atmospheres of DQ white dwarfs and in some DB stars. Our basic premise is that gravitational settling of C and O is slowed down by dying residual winds in the hot PG1159 phase and it is this competition that is ultimately responsible for the very existence of the PG1159 stars themselves and their progenies, the DO, DB, and DQ white dwarfs. Unlike some computations by other groups, we find that the carbon abundance pattern (N(C)/N(He) vs. Teff) uncovered recently by Dufour, Bergeron, & Fontaine (2005) in DQ stars can quite naturally be explained in terms of the dredge-up model developed by Pelletier et al. (1986). In particular, we recover quite well the observed trend of a monotonic decrease of the N(C)/N(He) ratio with decreasing effective temperature in those stars. The tight observational sequence found by Dufour et al. (and confirmed recently by Koester & Knist 2006) allows us to pin down accurately the masses of the He-dominated envelopes in DQ stars. The bulk of them appear to have envelopes containing about 10-2 to 10-3 of the total mass, in agreement with the expectations of ``born again'' post-AGB models such as those proposed by Herwig et al. (1999). In addition, we can account qualitatively for the pollution observed in the atmospheres of DB white dwarfs in terms of primordial carbon whose settling is slowed down, in the hotter phases of their evolution, by the presence of residual winds, in agreement with our original premise. We thus reaffirm the natural connection between PG1159, DO, DB, and DQ white dwarfs.

Brassard, P.; Fontaine, G.; Dufour, P.; Bergeron, P.

2007-09-01

419

The I2 dissociation mechanisms in the chemical oxygen-iodine laser revisited  

NASA Astrophysics Data System (ADS)

The recently suggested mechanism of I2 dissociation in the chemical oxygen-iodine laser (COIL) [K. Waichman, B. D. Barmashenko, and S. Rosenwaks, J. Appl. Phys. 106, 063108 (2009); and J. Chem. Phys. 133, 084301 (2010)] was largely based on the suggestion of V. N. Azyazov, S. Yu. Pichugin, and M. C. Heaven [J. Chem. Phys. 130, 104306 (2009)] that the vibrational population of O2(a) produced in the chemical generator is high enough to play an essential role in the dissociation. The results of model calculations based on this mechanism agreed very well with measurements of the small signal gain g, I2 dissociation fraction F, and temperature T in the COIL. This mechanism is here revisited, following the recent experiments of M. V. Zagidullin [Quantum Electron. 40, 794 (2010)] where the observed low population of O2(b, v = 1) led to the conclusion that the vibrational population of O2(a) at the outlet of the generator is close to thermal equilibrium value. This value corresponds to a very small probability, ~0.05, of O2(a) energy pooling to the states O2(X,a,b, v > 0). We show that the dissociation mechanism can reproduce the experimentally observed values of g, F, and T in the COIL only if most of the energy released in the processes of O2(a) energy pooling and O2(b) quenching by H2O ends up as vibrational energy of the products, O2(X,a,b), where the vibrational states v = 2 and 3 are significantly populated. We discuss possible reasons for the differences in the suggested vibrational population and explain how these differences can be reconciled.

Waichman, K.; Barmashenko, B. D.; Rosenwaks, S.

2012-06-01

420

Heparin and cancer revisited: mechanistic connections involving platelets, P-selectin, carcinoma mucins, and tumor metastasis.  

PubMed

Independent studies indicate that expression of sialylated fucosylated mucins by human carcinomas portends a poor prognosis because of enhanced metastatic spread of tumor cells, that carcinoma metastasis in mice is facilitated by formation of tumor cell complexes with blood platelets, and that metastasis can be attenuated by a background of P-selectin deficiency or by treatment with heparin. The effects of heparin are not primarily due to its anticoagulant action. Other explanations have been suggested but not proven. Here, we bring together all these unexplained and seemingly disparate observations, showing that heparin treatment attenuates tumor metastasis in mice by inhibiting P-selectin-mediated interactions of platelets with carcinoma cell-surface mucin ligands. Selective removal of tumor mucin P-selectin ligands, a single heparin dose, or a background of P-selectin deficiency each reduces tumor cell-platelet interactions in vitro and in vivo. Although each of these maneuvers reduced the in vivo interactions for only a few hours, all markedly reduce long-term organ colonization by tumor cells. Three-dimensional reconstructions by using volume-rendering software show that each situation interferes with formation of the platelet "cloak" around tumor cells while permitting an increased interaction of monocytes (macrophage precursors) with the malignant cells. Finally, we show that human P-selectin is even more sensitive to heparin than mouse P-selectin, giving significant inhibition at concentrations that are in the clinically acceptable range. We suggest that heparin therapy for metastasis prevention in humans be revisited, with these mechanistic paradigms in mind. PMID:11248082

Borsig, L; Wong, R; Feramisco, J; Nadeau, D R; Varki, N M; Varki, A

2001-03-13

421

Revisiting Christfried Jakob’s concept of the dual onto-phylogenetic origin and ubiquitous function of the cerebral cortex: a century of progress  

Microsoft Academic Search

This paper revisits a concept combining the evolution, ontogeny and histophysiology of the cerebral cortex, presented, in\\u000a a quest to explain cognition and behavior, by the neurobiologist Christfried Jakob (1866–1956) at the Second Annual Meeting\\u000a of the International Society for Medical Psychology and Psychotherapy, organized by Oskar Vogt (1870–1959) in Munich in 1911.\\u000a Jakob suggested a dual onto-phylogenetic origin and

Lazaros C. Triarhou

2010-01-01

422

The dynamics of a double-cell hydrothermal system in triggering seismicity at Somma-Vesuvius: results from a high-resolution radon survey (revisited)  

Microsoft Academic Search

Data collected at Somma-Vesuvius during the 1998–1999 radon surveys have been revisited and reinterpreted in light of recent\\u000a geophysical and geochemical information. The duration of selected radon anomalies, together with the decay properties of radon,\\u000a have been used to estimate the permeability and porosity of rocks of the deep hydrothermal system. The current local cyclic\\u000a seismicity is explained by means

Corrado Cigolini

2010-01-01

423

Quantum gates in hyperfine levels of ultracold alkali dimers by revisiting constrained-phase optimal control design.  

PubMed

We simulate the implementation of a 3-qubit quantum Fourier transform gate in the hyperfine levels of ultracold polar alkali dimers in their first two lowest rotational levels. The chosen dimer is (41)K(87)Rb supposed to be trapped in an optical lattice. The hyperfine levels are split by a static magnetic field. The pulses operating in the microwave domain are obtained by optimal control theory. We revisit the problem of phase control in information processing. We compare the efficiency of two optimal fields. The first one is obtained from a functional based on the average of the transition probabilities for each computational basis state but constrained by a supplementary transformation to enforce phase alignment. The second is obtained from a functional constructed on the phase sensitive fidelity involving the sum of the transition amplitudes without any supplementary constrain. PMID:23822306

Jaouadi, A; Barrez, E; Justum, Y; Desouter-Lecomte, M

2013-07-01

424

Re-visiting the observation of the ?v=-4 vibronic sequence of the C2 Swan system  

NASA Astrophysics Data System (ADS)

We re-visit the analysis of the ?v=-4 vibronic sequence of the C2 Swan system published recently by Yeung et al. [1] in which the heavily perturbed (4,8) band could not be assigned and analyzed satisfactorily. Here, we outline the assignment of 122 transitions of the band by taking into account a recent deperturbation study of the d3?g, v=4 level by Bornhauser et al. [2]. Improved molecular constants for the a3?u, v=8 and d3?g, v=4 states are presented by performing a least-squares fit to the Hamiltonian with a favorable root-mean square error of 0.012 cm-1.

Bornhauser, P.; Sych, Y.; Knopp, G.; Gerber, T.; Radi, P. P.

2013-05-01

425

Sterol Lipid Metabolism in Down Syndrome Revisited: Down Syndrome Is Associated with a Selective Reduction in Serum Brassicasterol Levels  

PubMed Central

Over the past 15 years, insights into sterol metabolism have improved our understanding of the relationship between lipids and common conditions such as atherosclerosis and Alzheimer's Disease (AD). A better understanding of sterol lipid metabolism in individuals with Down Syndrome (DS) may help elucidate how this population's unique metabolic characteristics influence their risks for atherosclerosis and AD. To revisit the question of whether sterol lipid parameters may be altered in DS subjects, we performed a pilot study to assess traditional serum sterol lipids and lipoproteins, as well as markers of sterol biosynthesis, metabolites, and plant sterols in 20 subjects with DS compared to age-matched controls. Here we report that the levels of nearly all lipids and lipoproteins examined are similar to control subjects, suggesting that trisomy 21 does not lead to pronounced general alterations in sterol lipid metabolism. However, the levels of serum brassicasterol were markedly reduced in DS subjects.

Tansley, Gavin; Holmes, Daniel T.; Lutjohann, Dieter; Head, Elizabeth; Wellington, Cheryl L.

2012-01-01

426

The AD775 cosmic event revisited: the Sun is to blame  

NASA Astrophysics Data System (ADS)

Aims: Miyake et al. (2012, Nature, 486, 240, henceforth M12) recently reported, based on 14C data, an extreme cosmic event in about AD775. Using a simple model, M12 claimed that the event was too strong to be caused by a solar flare within the standard theory. This implied a new paradigm of either an impossibly strong solar flare or a very strong cosmic ray event of unknown origin that occurred around AD775. However, as we show, the strength of the event was significantly overestimated by M12. Several subsequent works have attempted to find a possible exotic source for such an event, including a giant cometary impact upon the Sun or a gamma-ray burst, but they are all based on incorrect estimates by M12. We revisit this event with analysis of new datasets and consistent theoretical modelling. Methods: We verified the experimental result for the AD775 cosmic ray event using independent datasets including 10Be series and newly measured 14C annual data. We surveyed available historical chronicles for astronomical observations for the period around the AD770s to identify potential sightings of aurorae borealis and supernovae. We interpreted the 14C measurements using an appropriate carbon cycle model. Results: We show that: (1) The reality of the AD775 event is confirmed by new measurements of 14C in German oak; (2) by using an inappropriate carbon cycle model, M12 strongly overestimated the event's strength; (3) the revised magnitude of the event (the global 14C production Q = (1.1 - 1.5) × 108 atoms/cm2) is consistent with different independent datasets (14C, 10Be, 36Cl) and can be associated with a strong, but not inexplicably strong, solar energetic particle event (or a sequence of events), and provides the first definite evidence for an event of this magnitude (the fluence >30 MeV was about 4.5 × 1010 cm-2) in multiple datasets; (4) this interpretation is in agreement with increased auroral activity identified in historical chronicles. Conclusions: The results point to the likely solar origin of the event, which is now identified as the greatest solar event on a multi-millennial time scale, placing a strong observational constraint on the theory of explosive energy releases on the Sun and cool stars.

Usoskin, I. G.; Kromer, B.; Ludlow, F.; Beer, J.; Friedrich, M.; Kovaltsov, G. A.; Solanki, S. K.; Wacker, L.

2013-04-01

427

Revisiting the November 27, 1945 Makran (Mw=8.2) interplate earthquake  

NASA Astrophysics Data System (ADS)

Makran Subduction Zone (MSZ) in southern Iran and southwestern Pakistan is a zone of convergence, where the remnant oceanic crust of Arabian plate is subducting beneath the Eurasian plate with a rate of less than 30 mm/yr. The November 27, 1945 earthquake (Mw=8.2) in eastern section of Makran followed by a tsunami, at some points 15 meters high. More than 4000 victims and widespread devastation along the coastal area of Pakistan, Iran, Oman and India are reported for this earthquake. We have collected the old seismograms of the 1945 earthquake and its largest following earthquake (August 5, 1947, Mw=7.3) from a number of stations around the globe. Using ISS data, we relocated these two events. We used the teleseismic body-waveform inversion code of Kikuchi and Kanamori to determine the slip distribution of these two earthquakes for the first time. The results show that the extent of rupture of the 1945 earthquake is larger than what previously had been approximated in other studies. The slip distribution suggests two distinct sets of asperities with different behavior in the west close to Pasni and in the east close to Ormara. The highest slip was obtained for an area between these two cities which shows geological evidence of rapid uplift. To associate this behavior with the structure of slab interface we studied the TPGA (Trench Parallel Free-air Gravity Anomaly) and TPBA (Trench Parallel Bouguer Anomaly) in MSZ. The results of TPGA does not show the expected phenomenon, which is the correlation of asperities with the area of highly negative TPGA. However, TPBA can make correlation between the observed slip distribution and the structure of slab interface. Using the topography and gravity profiles perpendicular to trench and along the MSZ, we could observe the segmentation in the slab interface. This confirms that we barely expect that the whole interface releases energy in one single megathrust earthquake. Current seismicity in MSZ, although sparse, can fairly good confirm signals of a mature cycle of earthquake to the west of the rupture area of the 1945 event. These evidences include distribution of extensional earthquakes at intermediate depths and compressional events in the overriding plate. Revisiting the 1945 earthquake can provide lessons for understanding the behavior of MSZ and its future large events.

Zarifi, Z.; Raeesi, M.

2012-04-01

428

Substellar Objects in Nearby Young Clusters. VII. The Substellar Mass Function Revisited  

NASA Astrophysics Data System (ADS)

The abundance of brown dwarfs (BDs) in young clusters is a diagnostic of star formation theory. Here we revisit the issue of determining the substellar initial mass function (IMF) based on a comparison between NGC 1333 and IC348, two clusters in the Perseus star-forming region. We derive their mass distributions for a range of model isochrones, varying distances, extinction laws, and ages with comprehensive assessments of the uncertainties. We find that the choice of isochrone and other parameters have significant effects on the results, thus we caution against comparing IMFs obtained using different approaches. For NGC 1333, we find that the star/BD ratio R is between 1.9 and 2.4 for all plausible scenarios, consistent with our previous work. For IC348, R is found to be between 2.9 and 4.0, suggesting that previous studies have overestimated this value. Thus the star-forming process generates about 2.5-5 substellar objects per 10 stars. The derived star/BD ratios correspond to a slope of the power-law mass function of ? = 0.7-1.0 for the 0.03-1.0 M ? mass range. The median mass in these clusters—the typical stellar mass—is between 0.13 and 0.30 M ?. Assuming that NGC 1333 is at a shorter distance than IC348, we find a significant difference in the cumulative distribution of masses between the two clusters, resulting from an overabundance of very low mass objects in NGC 1333. Gaia astrometry will constrain the cluster distances better and will lead to a more definitive conclusion. Furthermore, the star/BD ratio is somewhat larger in IC348 compared with NGC 1333, although this difference is still within the margins of error. Our results indicate that environments with higher object density may produce a larger fraction of very low mass objects, in line with predictions for BD formation through gravitational fragmentation of filaments falling into a cluster potential.

Scholz, Alexander; Geers, Vincent; Clark, Paul; Jayawardhana, Ray; Muzic, Koraljka

2013-10-01

429

Correlating Subjective and Objective Sleepiness: Revisiting the Association Using Survival Analysis  

PubMed Central

Study Objectives: The Epworth Sleepiness Scale (ESS) and multiple sleep latency test (MSLT) are the most commonly used measures of subjective and objective sleepiness, respectively. The strength of the association between these measures as well as the optimal ESS threshold that indicates objective sleepiness remains a topic of significant interest in the clinical and research arenas. The current investigation sought to: (a) examine the association between the ESS and the average sleep latency from the MSLT using the techniques of survival analysis; (b) determine whether specific patient factors influence the association; (c) examine the utility of each ESS question; and (d) identify the optimal ESS threshold that indicates objective sleepiness. Design: Cross-sectional study. Patients and Settings: Patients (N = 675) referred for polysomnography and MSLT. Measurements and Results: Using techniques of survival analysis, a significant association was noted between the ESS score and the average sleep latency. The adjusted hazard ratios for sleep onset during the MSLT for the ESS quartiles were 1.00 (ESS < 9), 1.32 (ESS: 10–13), 1.85 (ESS: 14-17), and 2.53 (ESS ? 18), respectively. The association was independent of several patient factors and was distinct for the 4 naps. Furthermore, most of the ESS questions were individually predictive of the average sleep latency except the tendency to doze off when lying down to rest in the afternoon, which was only predictive in patients with less than a college education. Finally, an ESS score ? 13 optimally predicted an average sleep latency < 8 minutes. Conclusions: In contrast to previous reports, the association between the ESS and the average sleep latency is clearly apparent when the data are analyzed by survival analysis, and most of the ESS questions are predictive of objective sleepiness. An ESS score ? 13 most effectively predicts objective sleepiness, which is higher than what has typically been used in clinical practice. Given the ease of administering the ESS, it represents a relatively simple and cost-effective method for identifying individuals at risk for daytime sleepiness. Citation: Aurora RN; Caffo B; Crainiceanu C; Punjabi NM. Correlating subjective and objective sleepiness: revisiting the association using survival analysis. SLEEP 2011;34(12):1707-1714.

Aurora, R. Nisha; Caffo, Brian; Crainiceanu, Ciprian; Punjabi, Naresh M.

2011-01-01

430

The Steric Hypothesis for DNA Replication and Fluorine Hydrogen Bonding Revisited in Light of Structural Data  

PubMed Central

CONSPECTUS In DNA, bases pair in a molecular interaction that is both highly predictable and exquisitely specific. Therefore researchers have generally believed that the insertion of the matching nucleotide opposite a template base by DNA polymerases (pols) required Watson-Crick (W-C) hydrogen bond formation. However pioneering work by Kool and coworkers using hydrophobic base analogs such as the T isostere 2,4-difluorotoluene (F) showed that shape rather than H-bonding served as the primary source of specificity in DNA replication by certain pols. This steric hypothesis for DNA replication has gained popularity, perhaps discouraging further experimental studies to address potential limitations of this new idea. The idea that shape trumps H-bonding in terms of pol selectivity largely hinges on the belief that fluorine is a poor H-bond acceptor. However, the shape complementarity model was embraced in the absence of any detailed structural data for match (F:A) and mismatch pairs (F:G, F:C, F:T) in DNA duplexes or at active sites of pols. Although the F and T nucleosides are roughly isosteric, it is unclear whether F:A and T:A pairs exhibit similar geometries. If the former pair is devoid of H-bonding, it will be notably wider than a T:A pair. Because shape/size and H bonding are intimately related, it may not be possible to separate these two properties. Thus the geometries of an isolated F:A pair in water may differ considerably from an F:A pair embedded in a stretch of duplex DNA, at the tight active site of an A-family replicative pol, or within the spacious active site of a Y-family translesion pol. The shape complementarity model may have more significance for pol accuracy than efficiency: this model appears to be most relevant for replicative pols that use specific residues to probe the identity of the nascent base pair from the minor groove side. However, compared with W-C H-bonds researchers have not fully considered the importance of such interactions that include H-bonds in terms of pol fidelity and the shape complementarity model. This Account revisits the steric hypothesis for DNA replication in light of recent structural data and discusses the role of fluorine as an H-bond acceptor. Over the last five years, crystal structures have emerged for nucleic acid duplexes with F paired opposite to natural bases or located at the active sites of DNA pols. These data permit a more nuanced understanding of the role of shape in DNA replication and the capacity of fluorine to form H-bonds. These studies and additional research involving RNA or other fluorine-containing nucleoside analogs within duplexes indicate that fluorine engages in H-bonding in many cases. Although T and F are isosteric at the nucleoside level, replacement of a natural base by F in pairs often changes their shapes and sizes, and dF in DNA behaves differently from rF in RNA. Similarly, the pairing geometries observed for F and T opposite dATP, dGTP, dTTP or dCTP and their H-bonding patterns at the active site of a replicative pol differ considerably.

EGLI, MARTIN

2012-01-01

431

Revisiting olfactory classical conditioning of the proboscis extension response in honey bees: a step toward standardized procedures.  

PubMed

The honey bee Apis mellifera has emerged as a robust and influential model for the study of classical conditioning thanks to the existence of a powerful Pavlovian conditioning protocol, the olfactory conditioning of the proboscis extension response (PER). In 2011, the olfactory PER conditioning protocol celebrated its 50 years since it was first introduced by Kimihisa Takeda in 1961. In this protocol, individually harnessed honey bees are trained to associate an odor with sucrose solution. The resulting olfactory learning is fast and induces robust olfactory memories that have been characterized at the behavioral, neuronal and molecular levels. Despite the success of this protocol for studying the bases of learning and memory at these different levels, innumerable procedural variants have arisen throughout the years, which render comparative analyses of behavioral performances difficult. Moreover, because even slight variations in conditioning procedures may introduce significant differences in acquisition and retention performances, we revisit olfactory PER conditioning and define here a standardized framework for experiments using this behavioral protocol. To this end, we present and discuss all the methodological steps and details necessary for successful implementation of olfactory PER conditioning. PMID:22960052

Matsumoto, Yukihisa; Menzel, Randolf; Sandoz, Jean-Christophe; Giurfa, Martin

2012-08-31

432

Revisiting the spread spectrum effect in radio interferometric imaging: a sparse variant of the w-projection algorithm  

NASA Astrophysics Data System (ADS)

Next-generation radio interferometric telescopes will exhibit non-coplanar baseline configurations and wide field of views, inducing a w-modulation of the sky image, which induces the spread spectrum effect. We revisit the impact of this effect on the imaging quality and study a new algorithmic strategy to deal with the associated operator. In previous studies, it has been shown that image recovery in the framework of compressed sensing is improved due to this effect, where the w-modulation can increase the incoherence between measurement and sparsifying signal representations. For the purpose of computational efficiency, idealized experiments with a constant baseline component w were performed. We extend this analysis to the more realistic setting where the w-component varies for each visibility measurement. First, incorporating varying w-components into imaging algorithms is a computational demanding task. We propose a variant of the w-projection algorithm, which is based on an adaptive sparsification procedure, and incorporate it in compressed sensing imaging methods. Secondly, we show that for varying w-components, the reconstruction quality is significantly improved compared to no w-modulation, reaching levels comparable to a constant, maximal w-component. This finding confirms that one may seek to optimize future telescope configurations to promote large w-components, thus enhancing the fidelity of image reconstruction.

Wolz, L.; McEwen, J. D.; Abdalla, F. B.; Carrillo, R. E.; Wiaux, Y.

2013-10-01

433

Revisiting the Long/Soft-Short/Hard Classification of Gamma-Ray Bursts in the Fermi Era  

NASA Astrophysics Data System (ADS)

We perform a statistical analysis of the temporal and spectral properties of the latest Fermi gamma-ray bursts (GRBs) to revisit the classification of GRBs. We find that the bimodalities of duration and the energy ratio (E peak/Fluence) and the anti-correlation between spectral hardness (hardness ratio (HR), peak energy, and spectral index) and duration (T 90) support the long/soft-short/hard classification scheme for Fermi GRBs. The HR-T 90 anti-correlation strongly depends on the spectral shape of GRBs and energy bands, and the bursts with the curved spectra in the typical BATSE energy bands show a tighter anti-correlation than those with the power-law spectra in the typical BAT energy bands. This might explain why the HR-T 90 correlation is not evident for those GRB samples detected by instruments like Swift with a narrower/softer energy bandpass. We also analyze the intrinsic energy correlation for the GRBs with measured redshifts and well-defined peak energies. The current sample suggests E p, rest = 2455 × (E iso/1052)0.59 for short GRBs, significantly different from that for long GRBs. However, both the long and short GRBs comply with the same E p, rest-L iso correlation.

Zhang, Fu-Wen; Shao, Lang; Yan, Jing-Zhi; Wei, Da-Ming

2012-05-01

434

Podiform chromitite classification revisited: A comparison of discordant and concordant chromitite pods from Wadi Hilti, northern Oman ophiolite  

NASA Astrophysics Data System (ADS)

Two types of podiform chromitite, concordant and discordant, were examined in the mantle section of northern Oman ophiolite along Wadi Hilti, to revisit the structural classification of podiform chromitite. They are contrasted in mineral chemical characteristics, in addition to the difference in attitude; the Cr/(Cr + Al) atomic ratio of spinel is around 0.6 for the concordant chromitite and surrounding peridotites, but is around 0.7 for the discordant one and surrounding peridotites. Chromian spinel grains contain pargasite-rich inclusions of primary origin from the both types, but they are far less abundant and smaller in size in the concordant chromitite than in the discordant one. Thin lamellae of pyroxenes in chromian spinel, similar to those in ultrahigh-pressure (UHP) chromitites from Tibet, are available only from the concordant chromitite. The dunite enveloping the concordant chromitite is extraordinarily high in NiO (up to >0.5 wt.%), suggesting subsolidus Ni diffusion from the chromitite. The involved melt was quite different between the two types of chromitite; the melt to precipitate the discordant one was more hydrous than that for the concordant one because of far more abundance of hydrous minerals in the former. The difference in duration of subsolidus cooling, and probably decompression, is prominent between the two types of chromitite. The concordant chromitite cannot be formed from the discordant one simply by metamorphic conversion: the former is of deep magmatic origin whereas the latter, of shallow magmatic origin.

Miura, Makoto; Arai, Shoji; Ahmed, Ahmed H.; Mizukami, Tomoyuki; Okuno, Masayuki; Yamamoto, Shinji

2012-10-01

435

REVISITING THE LONG/SOFT-SHORT/HARD CLASSIFICATION OF GAMMA-RAY BURSTS IN THE FERMI ERA  

SciTech Connect

We perform a statistical analysis of the temporal and spectral properties of the latest Fermi gamma-ray bursts (GRBs) to revisit the classification of GRBs. We find that the bimodalities of duration and the energy ratio (E{sub peak}/Fluence) and the anti-correlation between spectral hardness (hardness ratio (HR), peak energy, and spectral index) and duration (T{sub 90}) support the long/soft-short/hard classification scheme for Fermi GRBs. The HR-T{sub 90} anti-correlation strongly depends on the spectral shape of GRBs and energy bands, and the bursts with the curved spectra in the typical BATSE energy bands show a tighter anti-correlation than those with the power-law spectra in the typical BAT energy bands. This might explain why the HR-T{sub 90} correlation is not evident for those GRB samples detected by instruments like Swift with a narrower/softer energy bandpass. We also analyze the intrinsic energy correlation for the GRBs with measured redshifts and well-defined peak energies. The current sample suggests E{sub p,rest} = 2455 Multiplication-Sign (E{sub iso}/10{sup 52}){sup 0.59} for short GRBs, significantly different from that for long GRBs. However, both the long and short GRBs comply with the same E{sub p,rest}-L{sub iso} correlation.

Zhang Fuwen; Yan Jingzhi; Wei Daming [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Shao Lang, E-mail: fwzhang@pmo.ac.cn [Department of Physics, Hebei Normal University, Shijiazhuang 050016 (China)

2012-05-10

436

Entropy is conserved in Hawking radiation as tunneling: A revisit of the black hole information loss paradox  

SciTech Connect

Research Highlights: > Information is found to be encoded and carried away by Hawking radiations. > Entropy is conserved in Hawking radiation. > We thus conclude no information is lost. > The dynamics of black hole may be unitary. - Abstract: We revisit in detail the paradox of black hole information loss due to Hawking radiation as tunneling. We compute the amount of information encoded in correlations among Hawking radiations for a variety of black holes, including the Schwarzchild black hole, the Reissner-Nordstroem black hole, the Kerr black hole, and the Kerr-Newman black hole. The special case of tunneling through a quantum horizon is also considered. Within a phenomenological treatment based on the accepted emission probability spectrum from a black hole, we find that information is leaked out hidden in the correlations of Hawking radiation. The recovery of this previously unaccounted for information helps to conserve the total entropy of a system composed of a black hole plus its radiations. We thus conclude, irrespective of the microscopic picture for black hole collapsing, the associated radiation process: Hawking radiation as tunneling, is consistent with unitarity as required by quantum mechanics.

Zhang Baocheng [State Key Laboratory of Magnetic Resonances and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Cai Qingyu, E-mail: qycai@wipm.ac.cn [State Key Laboratory of Magnetic Resonances and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Zhan Mingsheng [State Key Laboratory of Magnetic Resonances and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071 (China); You Li [Department of Physics, Tsinghua University, Beijing 100084 (China)

2011-02-15

437

Borobudur revisited: soy consumption may be associated with better recall in younger, but not in older, rural Indonesian elderly.  

PubMed

Previous reports have suggested that high frequent tofu consumption is associated with worse cognitive function in East Asian elderly. Some studies also found an increased risk of dementia with high tofu consumption in those older than 65years of age. Tofu and other soy products, such as tempeh, contain high levels of plant estrogens or isoflavones. This study revisited a rural Central Javanese population (56-97 years of age) who were covered by the Borobudur District Health Centers. Data on cognitive performance were available for n=142 participants. Results showed positive linear associations of weekly tofu (beta=.22, p<0.05) and tempeh (beta=.23, p<0.01) consumption with immediate recall, which were significant in those with an average age of 67 years. In those with an average age of 80 years, the earlier reported negative association of tofu with immediate recall was no longer significant. Lifestyle changes (reduction of tofu consumption after dissemination of results) or "healthy survivor effects" may have been responsible for this finding. These findings may be reminiscent of the "Window of Opportunity" theory, which suggests that estrogenic compounds can exert positive effects on verbal memory, but not in older men and women, when no or negative effects of these compounds on brain cells and cognition have been found. Long-term, placebo-controlled treatment studies should investigate whether tempeh, a fermented soybean product that also contains folate, can maintain cognitive function in middle-aged and elderly participants. PMID:21035431

Hogervorst, Eef; Mursjid, Fidiansjah; Priandini, Dewi; Setyawan, Henry; Ismael, Raden Irawati; Bandelow, Stephan; Rahardjo, Tri Budi

2010-10-28

438

'There and back again': revisiting the pathophysiological roles of human endogenous retroviruses in the post-genomic era  

PubMed Central

Almost 8% of the human genome comprises endogenous retroviruses (ERVs). While they have been shown to cause specific pathologies in animals, such as cancer, their association with disease in humans remains controversial. The limited evidence is partly due to the physical and bioethical restrictions surrounding the study of transposons in humans, coupled with the major experimental and bioinformatics challenges surrounding the association of ERVs with disease in general. Two biotechnological landmarks of the past decade provide us with unprecedented research artillery: (i) the ultra-fine sequencing of the human genome and (ii) the emergence of high-throughput sequencing technologies. Here, we critically assemble research about potential pathologies of ERVs in humans. We argue that the time is right to revisit the long-standing questions of human ERV pathogenesis within a robust and carefully structured framework that makes full use of genomic sequence data. We also pose two thought-provoking research questions on potential pathophysiological roles of ERVs with respect to immune escape and regulation.

Magiorkinis, Gkikas; Belshaw, Robert; Katzourakis, Aris

2013-01-01

439

Top-down control in a patchy environment: revisiting the stabilizing role of food-dependent predator dispersal.  

PubMed

In this paper, we revisit the stabilizing role that predator dispersal and aggregation have in the top-down regulation of predator-prey systems in a heterogeneous environment. We consider an environment consisting of sites interconnected by dispersal, and propose a novel mechanism of stabilization for the case with a non-sigmoid functional response of predators. We assume that the carrying capacity of the prey is infinitely large in each site, and show that successful top-down regulation of this otherwise globally unstable system is made possible through an interplay between the unevenness of prey fitness across the sites and the rapid food-dependent migration of predators. We argue that this mechanism of stabilization is different from those previously reported in the literature: in particular, it requires a high degree of synchronicity in local oscillations of species densities across the sites. Prey outbreaks take place synchronously, but the unevenness of prey growth rates across the sites results in a pronounced difference in the species densities, and so the predator quickly disperses to the sites with the highest prey abundances. For this reason, the consumption of prey mostly takes place in the sites with high densities of prey, which assures an efficient suppression of outbreaks. Furthermore, when the total size of prey population is low, the distribution of both species among the sites becomes more even, and this prevents overconsumption of the prey by the predator. Finally, we put forward the hypothesis that this mechanism, when considered in a tri-trophic plankton community in the water column, can explain the stability of the nutrient-rich low-chlorophyll open ocean regions. PMID:22079669

Morozov, Andrew; Sen, Moitri; Banerjee, Malay

2011-11-04

440

Revisiting the melting temperature of NpO2 and the challenges associated with high temperature actinide compound measurements  

NASA Astrophysics Data System (ADS)

This work revisits the melting behaviour of neptunium dioxide, an actinide compound which can be produced in the nuclear fuel during operation, and which has an important impact on the nuclear fuel and waste radioactivity especially on the very long term. The present experimental approach employs remote laser heating under controlled atmosphere and fast pyrometry. This technique circumvents problems encountered by more traditional heating techniques, in particular, the reaction between sample and containment at temperatures beyond 2500 K. In addition, only a small amount of sample material is required, which is an advantage with respect to the radioactivity and limited availability of neptunium. The NpO2 melting/freezing temperature has been measured to be 3070 K +/- 62 K, much higher than previous values (around 2830 K) obtained by more traditional thermal analysis methods. The large amount of experimental data collected allowed a consistent statistical analysis. It seems likely, although not fully evident from the present results, that the high oxygen potential at temperatures around melting leads to a slightly hypo-stoichiometric congruent melting composition, as already observed in other actinide (ThO2, PuO2) and lanthanide oxides (e.g., CeO2). Finally, a recently developed phase-field model was used for the simulation of the observed thermograms, allowing a deeper insight in material properties that are difficult to directly measure. For example, a polaron contribution to the high-temperature thermal conductivity, well accepted for the commonly studied actinide oxide UO2, is shown here to likely be present in NpO2.

Böhler, R.; Welland, M. J.; Bruycker, F. De; Boboridis, K.; Janssen, A.; Eloirdi, R.; Konings, R. J. M.; Manara, D.

2012-06-01

441

New and revisited paleomagnetic data from Permian-Triassic red beds: Two kinematic domains in the west-central Pyrenees  

NASA Astrophysics Data System (ADS)

New paleomagnetic results of Permian-Triassic red beds from Bielsa, Aure and Somport-Anayet sectors in the Pyrenean Axial Zone are presented and combined with revisited and reviewed paleomagnetic data from the west-central Pyrenees. The paleomagnetic data from the red beds vary between different sectors that share similar structural position; i.e. whilst all sectors share the existence of a characteristic prefolding component, a Cenozoic postfolding component is found only in one area but not in other areas with similar structural position and kinematics. Previous paleomagnetic data to the west of the studied zone reveal a pre-Turonian remagnetization component, but this secondary component is not found in an area that shares a similar structural position (Aure). This variability suggests that the paleomagnetic behavior is the result of a series of factors related to the particular tectonic history of the region (sedimentation, burial, and deformation during basin inversion) and therefore paleomagnetic data demands careful assessment in order to unravel the kinematics of areas with equivalent structural positions in orogens.However, important kinematic implications that hold in the Pyrenees can be inferred from the restoration of the Permian-Triassic characteristic magnetizations to positions previous to the paleomagnetic rotations recorded by Cretaceous or Cenozoic paleomagnetic data. The restoration reveals on one hand the lack of large rotations in the South Pyrenenan Zone except in the Nogueras area, according to Bates (1989), and on the other hand, the contrasting rotations recorded to the west of the studied zone, in the Paleozoic Basque Massifs (PBM) and the South-Pyrenean Zone, indicating the existence of two different tectonic domains in the west-central sector of the Pyrenees. The strong clockwise rotations postdating the Early Cretaceous remagnetization that are recorded in the PBM and in the North Pyreneean Zone, suggest a late dextral shear deformation affecting areas near the North Pyrenean Fault Zone.

Oliva-Urcia, Belén; Pueyo, Emilio L.; Larrasoaña, Juan Cruz; Casas, Antonio M.; Román-Berdiel, Teresa; van der Voo, Rob; Scholger, Robert

2012-02-01

442

From the Blazar Sequence to the Blazar Envelope: Revisiting the Relativistic Jet Dichotomy in Radio-loud Active Galactic Nuclei  

NASA Astrophysics Data System (ADS)

We revisit the concept of a blazar sequence that relates the synchrotron peak frequency (?peak) in blazars with synchrotron peak luminosity (L peak, in ?L ?) using a large sample of radio-loud active galactic nuclei. We present observational evidence that the blazar sequence is formed from two populations in the synchrotron ?peak-L peak plane, each forming an upper edge to an envelope of progressively misaligned blazars, and connecting to an adjacent group of radio galaxies having jets viewed at much larger angles to the line of sight. When binned by jet kinetic power (L kin; as measured through a scaling relationship with extended radio power), we find that radio core dominance decreases with decreasing synchrotron L peak, revealing that sources in the envelope are generally more misaligned. We find population-based evidence of velocity gradients in jets at low kinetic powers (~1042-1044.5 erg s-1), corresponding to Fanaroff-Riley (FR) I radio galaxies and most BL Lac objects. These low jet power "weak-jet" sources, thought to exhibit radiatively inefficient accretion, are distinguished from the population of non-decelerating, low synchrotron-peaking (LSP) blazars and FR II radio galaxies ("strong" jets) which are thought to exhibit radiatively efficient accretion. The two-population interpretation explains the apparent contradiction of the existence of highly core-dominated, low-power blazars at both low and high synchrotron peak frequencies, and further implies that most intermediate synchrotron peak sources are not intermediate in intrinsic jet power between LSP and high synchrotron-peaking (HSP) sources, but are more misaligned versions of HSP sources with similar jet powers.

Meyer, Eileen T.; Fossati, Giovanni; Georganopoulos, Markos; Lister, Matthew L.

2011-10-01

443

Revisiting the Wilson-Jungner criteria: How can supplemental criteria guide public health in the era of genetic screening?  

PubMed

PURPOSE:: Advances in technology have made newborn screening for more than 50 inborn errors of metabolism possible using a dried blood sample. A framework is proposed that public health practitioners may use when considering candidate disorders for newborn screening panels. METHODS:: The framework expands on the 10 Wilson-Jungner criteria with the addition of 11 criteria specific to newborn screening. A calculation, the "pNBS Decision Score," is used to quantify results and rank candidate disorders. RESULTS:: The pNBS Decision Scores that were calculated for phenylketonuria (OMIM# 261600), cystic fibrosis (OMIM# 219700), Pompe disease (OMIM# 232300), and severe combined immunodeficiency (OMIM# 102700) support their inclusion as newborn screening disorders. The pNBS Decision Score suggests that Krabbe disease (OMIM# 245200) is not a candidate disorder for inclusion at this time. CONCLUSION:: The proposed framework adds to the ability of policy makers to quantify an essential portion of the process for adding disorders to newborn screening panels. Other factors such as ethical, legal, and social issues, clinical utility, and advocacy are also part of the policy process. The framework is not intended to replace existing nomination processes but rather to enhance those processes by encouraging iterative review of newborn screening-specific criteria. The use of the framework will provide consistency across a portion of the decision process. The public health community should take the opportunity to revisit the screening determinants of the Wilson-Jungner criteria from a 21st century perspective. The results suggest that this framework provides the public health practitioner with a consistent process for making an evidence-based decision. PMID:21983595

Petros, Michael

2011-10-01

444

B_s^0 - overline B_s^0 mixing in a family non-universal Z' model revisited  

NASA Astrophysics Data System (ADS)

Motivated by the very recent measurements performed at the LHCb and the Tevatron of the B_s^0 - overline B_s^0 mixing, in this paper we revisit it in a family non-universal Z' model, to check if a simultaneous explanation for all the mixing observables, especially for the like-sign dimuon charge asymmetry observed by the D0 collaboration, could be made in such a specific model. In the first scenario where the Z' boson contributes only to the off-diagonal element M_{{{12}}}^s , it is found that, once the combined constraints from ? M s , ? s and ?? s are imposed, the model could not explain the measured flavour-specific CP asymmetry a_{{fs}}^s