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1

Q-Ball of Inferior Fronto-Occipital Fasciculus and Beyond  

PubMed Central

The inferior fronto-occipital fasciculus (IFOF) is historically described as the longest associative bundle in the human brain and it connects various parts of the occipital cortex, temporo-basal area and the superior parietal lobule to the frontal lobe through the external/extreme capsule complex. The exact functional role and the detailed anatomical definition of the IFOF are still under debate within the scientific community. In this study we present a fiber tracking dissection of the right and left IFOF by using a q-ball residual-bootstrap reconstruction of High-Angular Resolution Diffusion Imaging (HARDI) data sets in 20 healthy subjects. By defining a single seed region of interest on the coronal fractional anisotropy (FA) color map of each subject, we investigated all the pathways connecting the parietal, occipital and posterior temporal cortices to the frontal lobe through the external/extreme capsule. In line with recent post-mortem dissection studies we found more extended anterior-posterior association connections than the “classical” fronto-occipital representation of the IFOF. In particular the pathways we evidenced showed: a) diffuse projections in the frontal lobe, b) fronto-parietal lobes connections trough the external capsule in almost all the subjects and c) widespread connections in the posterior regions. Our study represents the first consistent in vivo demonstration across a large group of individuals of these novel anterior and posterior terminations of the IFOF detailed described only by post-mortem anatomical dissection. Furthermore our work establishes the feasibility of consistent in vivo mapping of this architecture with independent in vivo methodologies. In conclusion q-ball tractography dissection supports a more complex definition of IFOF, which includes several subcomponents likely underlying specific function.

Amirbekian, Bagrat; Berger, Mitchel S.; Henry, Roland G.

2014-01-01

2

The anatomy of fronto-occipital connections from early blunt dissections to contemporary tractography.  

PubMed

The occipital and frontal lobes are anatomically distant yet functionally highly integrated to generate some of the most complex behaviour. A series of long associative fibres, such as the fronto-occipital networks, mediate this integration via rapid feed-forward propagation of visual input to anterior frontal regions and direct top-down modulation of early visual processing. Despite the vast number of anatomical investigations a general consensus on the anatomy of fronto-occipital connections is not forthcoming. For example, in the monkey the existence of a human equivalent of the 'inferior fronto-occipital fasciculus' (iFOF) has not been demonstrated. Conversely, a 'superior fronto-occipital fasciculus' (sFOF), also referred to as 'subcallosal bundle' by some authors, is reported in monkey axonal tracing studies but not in human dissections. In this study our aim is twofold. First, we use diffusion tractography to delineate the in vivo anatomy of the sFOF and the iFOF in 30 healthy subjects and three acallosal brains. Second, we provide a comprehensive review of the post-mortem and neuroimaging studies of the fronto-occipital connections published over the last two centuries, together with the first integral translation of Onufrowicz's original description of a human fronto-occipital fasciculus (1887) and Muratoff's report of the 'subcallosal bundle' in animals (1893). Our tractography dissections suggest that in the human brain (i) the iFOF is a bilateral association pathway connecting ventro-medial occipital cortex to orbital and polar frontal cortex, (ii) the sFOF overlaps with branches of the superior longitudinal fasciculus (SLF) and probably represents an 'occipital extension' of the SLF, (iii) the subcallosal bundle of Muratoff is probably a complex tract encompassing ascending thalamo-frontal and descending fronto-caudate connections and is therefore a projection rather than an associative tract. In conclusion, our experimental findings and review of the literature suggest that a ventral pathway in humans, namely the iFOF, mediates a direct communication between occipital and frontal lobes. Whether the iFOF represents a unique human pathway awaits further ad hoc investigations in animals. PMID:23137651

Forkel, Stephanie J; Thiebaut de Schotten, Michel; Kawadler, Jamie M; Dell'Acqua, Flavio; Danek, Adrian; Catani, Marco

2014-07-01

3

Effects of fronto-occipital cranial reshaping on mandibular form.  

PubMed

Cultural reshaping (artificial deformation or modification) of the neurocranial vault provides an artificially increased range of morphological variability within which the relationship between the growing neurocranium and face can be investigated. We analyze crania which have been fronto-occipitally compressed to ascertain possible morphological effects on the mandible. We collected measures of mandibular breadth, length, and height from 82 modified (N = 48) and unmodified (N = 34) crania from a Peruvian Ancon series. Angle classification was also scored in order to investigate whether or not occlusal relationships were affected by neurocranial reshaping. Only intercondylar distance (posterior mandibular breadth) exhibited significant differences between unmodified and modified groups, though this difference was relatively small compared with vault deformation. The modified crania had a higher frequency of normal occlusion (Class I) than the unmodified crania. Increased intercondylar breadth in modified skulls is due to a cascade of effects which begin with a direct effect of the fronto-occipital deforming device on neurocranial shape (increased neurocranial width). The increase in mandibular breadth may be a compensatory response to increased cranial base breadth and maintains articulation between the cranial base and mandible. The increased posterior breadth, coupled with a slight decrease in mandibular depth, may contribute to the change in occlusal relationships suggested for this sample. PMID:1543243

Cheverud, J M; Midkiff, J E

1992-02-01

4

Maxillary changes and occlusal traits in crania with artificial fronto-occipital deformation.  

PubMed

Artificial fronto-occipital deformation of the cranial vault was typical of pre-Columbian cultures in the central Andean coastal regions. We have studied the influence of this deformation on maxillary and mandibular morphology. Measurements were performed on 86 adult Ancon skulls with anteroposterior deformation. Undeformed skulls from the area of Makatampu (n = 52) were used as the control group. To explore the influence of the deformity on occlusion, the skulls were categorized using the Angle classification and the alignment of the interincisor midline. In the group of deformed skulls, there was an increase in lateral growth of the vault and of the base of the skull (P < 0.001), giving rise to a greater interpterygoid width of the maxilla (P < 0.001), and an increase in the transverse diameter of the palatal vault. The mandible presented an increase in the length of the rami (P < 0.001) and in the intercondylar width, with no alteration of mandibular length. The deformed skulls had normal (class I) occlusion, with no displacement of the midline. The difference in the asymmetry index between the two groups was not statistically significant. Artificial fronto-occipital deformation of the cranial vault provoked compensatory lateral expansion of the base that was correlated with the transverse development of the maxilla and mandible. Occlusion and sagittal intermaxillary position were not affected by the cranial deformity. These results provide evidence of the integration between the neurocranium and the viscerocranium in craniofacial development, and support the hypothesis of a compensatory effect of function. PMID:21990029

Jimenez, Publio; Martinez-Insua, Arturo; Franco-Vazquez, Jaime; Otero-Cepeda, Xose Luis; Santana, Urbano

2012-01-01

5

Damage to the left ventral, arcuate fasciculus and superior longitudinal fasciculus-related pathways induces deficits in object naming, phonological language function and writing, respectively.  

PubMed

The anatomic localization of brain functions can be characterized via diffusion tensor imaging in patients with brain tumors and neurological symptoms. The goal of the present study was to evaluate the function of the ventral, arcuate fasciculus (AF) and the superior longitudinal fasciculus (SLF)-related language pathways using these techniques by analyzing 9 patients treated in our hospital between 2007 and 2011. In cases 1-3, the left ventral pathways, namely, the inferior longitudinal fasciculus, uncinate fasciculus or inferior fronto-occipital fasciculus, were mainly damaged, and the common dysfunction experienced by these patients was a deficit in object naming. In cases 4-6, the left SLF was mainly damaged, and the common deficit was dysgraphia. In cases 7-9, the left AF was mainly damaged, and almost all language functions related to phonology were abnormal. These results suggest that the left ventral, AF and SLF-related pathways are closely related to visual, auditory and hand-related language function, respectively. PMID:23311714

Shinoura, Nobusada; Midorikawa, Akira; Onodera, Toshiyuki; Tsukada, Masanobu; Yamada, Ryozi; Tabei, Yusuke; Itoi, Chisato; Saito, Seiko; Yagi, Kazuo

2013-07-01

6

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

2012-01-01

7

Neuropsychological evidence for the functional role of the uncinate fasciculus in semantic control.  

PubMed

Understanding a word requires mapping sounds to a word-form and then identifying its correct meaning, which in some cases necessitates the recruitment of cognitive control processes to direct the activation of semantic knowledge in a task appropriate manner (i.e., semantic control). Neuroimaging and neuropsychological studies identify a fronto-temporal network important for word comprehension. However, little is known about the connectional architecture subserving controlled retrieval and selection of semantic knowledge during word comprehension. We used diffusion tensor imaging (DTI) and resting-state functional magnetic resonance imaging (rs-fMRI) in aphasic individuals with varying degrees of word comprehension deficits to examine the role of three white matter pathways within this network: the uncinate fasciculus (UF), inferior longitudinal fasciculus (ILF), and inferior fronto-occipital fasciculus (IFOF). Neuroimaging data from a group of age-matched controls were also collected in order to establish that the patient group had decreased structural and functional connectivity profiles. We obtained behavioral data from aphasic participants on two measures of single word comprehension that involve semantic control, and assessed pathway functional significance by correlating patients' performance with indices of pathway structural integrity and the functional connectivity profiles of regions they connect. Both the structural integrity of the UF and the functional connectivity strength of regions it connects predicted patients' performance. This result suggests the semantic control impairment in word comprehension resulted from poor neural communication between regions the UF connects. Inspections of other subcortical and cortical structures revealed no relationship with patients' performance. We conclude that the UF mediates semantic control during word comprehension by connecting regions specialized for cognitive control with those storing word meanings. These findings also support a relationship between structural and functional connectivity measures, as the rs-fMRI results provide converging evidence with those obtained using DTI. PMID:23395830

Harvey, Denise Y; Wei, Tao; Ellmore, Timothy M; Hamilton, A Cris; Schnur, Tatiana T

2013-04-01

8

Structural connectivity in a single case of progressive prosopagnosia: The role of the right inferior longitudinal fasciculus.  

PubMed

Progressive prosopagnosia (PP) is a clinical syndrome characterized by a progressive and selective inability to recognize and identify faces of familiar people. Here we report a patient (G.S.) with PP, mainly related to a prominent deficit in recognition of familiar faces, without a semantic (cross-modal) impairment. An in-depth evaluation showed that his deficit extended to other classes of objects, both living and non-living. A follow-up neuropsychological assessment did not reveal substantial changes after about 1 year. Structural MRI showed predominant right temporal lobe atrophy. Diffusion tensor imaging was performed to elucidate structural connectivity of the inferior longitudinal fasciculus (ILF) and the inferior fronto-occipital fasciculus (IFOF), the two major tracts that project through the core fusiform region to the anterior temporal and frontal cortices, respectively. Right ILF was markedly reduced in G.S., while left ILF and IFOFs were apparently preserved. These data are in favour of a crucial role of the neural circuit subserved by right ILF in the pathogenesis of PP. PMID:23099263

Grossi, Dario; Soricelli, Andrea; Ponari, Marta; Salvatore, Elena; Quarantelli, Mario; Prinster, Anna; Trojano, Luigi

2014-07-01

9

AN AFFERENT SYSTEM IN THE CENTRAL TEGMENTAL FASCICULUS  

Microsoft Academic Search

The brainstem course of the limb afferent component of the central tegmental fasciculus has been determined in both the cat and the phalanger, Trichosurus vulpecula, using evoked potentials. Unit records obtained from the reticular formation indicate that the ascending central tegmental fasciculus arises in large part from the level of the superior olives. The termination of the system is found

Barbara J Dennis; DIB Kerr

1961-01-01

10

Is the left uncinate fasciculus essential for language?  

Microsoft Academic Search

Despite a better understanding of the anatomy of the uncinate fasciculus (UF), its function remains poorly known. Our aim\\u000a was to study the exact role of UF in language, and the possible existence of parallel distributed language networks within\\u000a the “ventral stream”, underlaid by distinct subcortical tracts – namely the inferior occipito-temporal fasciculus (IOF) and\\u000a UF.\\u000a \\u000a We report a series

Hugues Duffau; Peggy Gatignol; Sylvie Moritz-Gasser; Emmanuel Mandonnet

2009-01-01

11

Dissecting the uncinate fasciculus: disorders, controversies and a hypothesis.  

PubMed

The uncinate fasciculus is a bidirectional, long-range white matter tract that connects lateral orbitofrontal cortex and Brodmann area 10 with the anterior temporal lobes. Although abnormalities in the uncinate fasciculus have been associated with several psychiatric disorders and previous studies suggest it plays a putative role in episodic memory, language and social emotional processing, its exact function is not well understood. In this review we summarize what is currently known about the anatomy of the uncinate, we review its role in psychiatric and neurological illnesses, and we evaluate evidence related to its putative functions. We propose that an overarching role of the uncinate fasciculus is to allow temporal lobe-based mnemonic associations (e.g. an individual's name + face + voice) to modify behaviour through interactions with the lateral orbitofrontal cortex, which provides valence-based biasing of decisions. The bidirectionality of the uncinate fasciculus information flow allows orbital frontal cortex-based reward and punishment history to rapidly modulate temporal lobe-based mnemonic representations. According to this view, disruption of the uncinate may cause problems in the expression of memory to guide decisions and in the acquisition of certain types of learning and memory. Moreover, uncinate perturbation should cause problems that extend beyond memory to include social-emotional problems owing to people and objects being stripped of personal value and emotional history and lacking in higher-level motivational value. PMID:23649697

Von Der Heide, Rebecca J; Skipper, Laura M; Klobusicky, Elizabeth; Olson, Ingrid R

2013-06-01

12

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

13

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

14

Diffusion Tensor Anisotropy in Adolescents and Adults  

Microsoft Academic Search

We acquired diffusion tensor images on 33 normal adults aged 22–64 and 15 adolescents aged 14–21. We assessed relative anisotropy in stereotaxically located regions of interest in the internal capsule, corpus callosum, anterior thalamic radiations, frontal anterior fasciculus, fronto-occipital fasciculus, temporal lobe white matter, cingulum bundle, frontal inferior longitudinal fasciculus, frontal superior longitudinal fasciculus, and optic radiations. All of these

Jason S. Schneiderman; Monte S. Buchsbaum; M. Mehmet. Haznedar; Erin A. Hazlett; Adam M. Brickman; Lina Shihabuddin; Jesse G. Brand; Yuliya Torosjan; Randall E. Newmark; Cheuk Tang; Jonathan Aronowitz; Reshmi Paul-Odouard; William Byne; Patrick R. Hof

2007-01-01

15

Quantitative Diffusion Tensor Tractography of Association and Projection Fibers in Normally Developing Children and Adolescents  

Microsoft Academic Search

Whole-brain diffusion tensor tractography (DTT) at high signal-to- noise ratio and angular and spatial resolutions were utilized to study the effects of age, sex differences, and lateral asymmetries of 6 white matter pathways (arcuate fasciculus (AF), inferior longitudinal fasciculus, inferior fronto-occipital fasciculus (IFOF), uncinate fasciculus (UF), corticospinal tract (CST), and somato- sensory pathway (SS)) in 31 right-handed children (6--17 years).

Thomas J. Eluvathingal; Khader M. Hasan; Larry Kramer; Jack M. Fletcher; Linda Ewing-Cobbs

2007-01-01

16

Naming and the role of the uncinate fasciculus in language function.  

PubMed

In this paper, an overview of the studies relating naming to the uncinate fasciculus is reported. With the introduction of contemporary neuroimaging techniques, namely of diffusion tensor imaging, white matter tracts have been investigated more thoroughly and possible changes in the uncinate fasciculus integrity have been correlated to different neuropsychological deficits. Although previous research has proposed a role of the left uncinate fasciculus on action and object naming or in semantic processing, a more recent study has suggested that naming famous people could be the most relevant task in which this bundle is involved, the semantic component being intact. The uncinate fasciculus connects the orbitofrontal cortex, involved in face encoding and in processing famous names, to the temporal pole, which is crucial in naming people. This conclusion is supported by the fact that tip-of-the-tongue states in older adults with reduced integrity of the uncinate fasciculus mainly concern proper names. PMID:21853238

Papagno, Costanza

2011-12-01

17

Superior longitudinal fasciculus and language functioning in healthy aging.  

PubMed

Structural deterioration of brain tissue in older adults is thought to be responsible for the majority of age-related cognitive decline. Disruption of widespread cortical networks due to a loss of axonal integrity may also play an important role. Research examining correlations between structural change and functional decline has focused heavily on working memory, processing speed, and executive processes while other aspects of cognition, such as language functioning, have received less attention. The current study aimed to determine whether age-related changes in the superior longitudinal fasciculus (SLF), are responsible for the deterioration in language functioning associated with age. Subjects included 112 right-handed volunteers (ages 19-76). For each subject, the SLF of the left hemisphere was reconstructed from diffusion tensor images (DTI). Mean fractional anisotropy (FA) values were extracted from parietal (SLFp) and temporal (SLFt) bundles. Language functioning was measured using the Peabody Picture Vocabulary Test (PPVT), Boston Naming Test (BNT), Controlled Oral Word Association Test (COWAT), and Semantic Fluency Test (SFT). Regression analyses revealed that males and females showed a different pattern of decline in FA across adulthood. For males, greater SLFt FA was significantly associated with increased COWAT performance, and there was a positive relationship between both age and SLFp FA with BNT scores. In females, greater SLFp FA was related to lower COWAT performance. Taken together, the results suggest that white matter integrity of the SLF follows a different pattern of decline in adulthood for males and females, and this decline differentially affects language functioning. PMID:24680744

Madhavan, Kiely M; McQueeny, Tim; Howe, Steven R; Shear, Paula; Szaflarski, Jerzy

2014-05-01

18

Microstructural connectivity of the arcuate fasciculus in adolescents with high-functioning autism  

PubMed Central

The arcuate fasciculus is a white matter fiber bundle of great importance in language. In this study, diffusion tensor imaging (DTI) was used to infer white matter integrity in the arcuate fasciculi of a group of subjects with high-functioning autism and a control group matched for age, handedness, IQ, and head size. The arcuate fasciculus for each subject was automatically extracted from the imaging data using a new volumetric DTI segmentation algorithm. The results showed a significant increase in mean diffusivity (MD) in the autism group, due mostly to an increase in the radial diffusivity (RD). A test of the lateralization of DTI measurements showed that both MD and fractional anisotropy (FA) were less lateralized in the autism group. These results suggest that white matter microstructure in the arcuate fasciculus is affected in autism and that the language specialization apparent in the left arcuate of healthy subjects is not as evident in autism, which may be related to poorer language functioning.

Fletcher, P. Thomas; Whitaker, Ross T.; Tao, Ran; DuBray, Molly B.; Froehlich, Alyson; Ravichandran, Caitlin; Alexander, Andrew L.; Bigler, Erin D.; Lange, Nicholas; Lainhart, Janet E.

2010-01-01

19

Pre-cue Fronto-Occipital Alpha Phase and Distributed Cortical Oscillations Predict Failures of Cognitive Control  

PubMed Central

Cognitive control is required for correct performance on antisaccade tasks, including the ability to inhibit an externally driven ocular motor repsonse (a saccade to a peripheral stimulus) in favor of an internally driven ocular motor goal (a saccade directed away from a peripheral stimulus). Healthy humans occasionally produce errors during antisaccade tasks, but the mechanisms associated with such failures of cognitive control are uncertain. Most research on cognitive control failures focuses on post-stimulus processing, although a growing body of literature highlights a role of intrinsic brain activity in perceptual and cognitive performance. The current investigation used dense array electroencephalography and distributed source analyses to examine brain oscillations across a wide frequency bandwidth in the period prior to antisaccade cue onset. Results highlight four important aspects of ongoing and preparatory brain activations that differentiate error from correct antisaccade trials: (i) ongoing oscillatory beta (20–30Hz) power in anterior cingulate prior to trial initiation (lower for error trials), (ii) instantaneous phase of ongoing alpha-theta (7Hz) in frontal and occipital cortices immediately before trial initiation (opposite between trial types), (iii) gamma power (35–60Hz) in posterior parietal cortex 100 ms prior to cue onset (greater for error trials), and (iv) phase locking of alpha (5–12Hz) in parietal and occipital cortices immediately prior to cue onset (lower for error trials). These findings extend recently reported effects of pre-trial alpha phase on perception to cognitive control processes, and help identify the cortical generators of such phase effects.

Hamm, Jordan P.; Dyckman, Kara A.; McDowell, Jennifer E.; Clementz, Brett A.

2012-01-01

20

White matter tracts in first-episode psychosis: A DTI tractography study of the uncinate fasciculus  

Microsoft Academic Search

A model of disconnectivity involving abnormalities in the cortex and connecting white matter pathways may explain the symptoms and cognitive abnormalities of schizophrenia. Recently, diffusion imaging tractography has made it possible to study white matter pathways in detail, and we present here a study of patients with first-episode psychosis using this technique. We studied the uncinate fasciculus (UF), the largest

Gary Price; Mara Cercignani; Geoffrey J. M. Parker; Daniel R. Altmann; Thomas R. E. Barnes; Gareth J. Barker; Eileen M. Joyce; Maria A. Ron

2008-01-01

21

The relationship between uncinate fasciculus white matter integrity and verbal memory proficiency in children.  

PubMed

During childhood, verbal learning and memory are important for academic performance. Recent functional MRI studies have reported on the functional correlates of verbal memory proficiency, but few have reported the underlying structural correlates. The present study sought to test the relationship between fronto-temporal white matter integrity and verbal memory proficiency in children. Diffusion weighted images were collected from 17 Black children (age 8-11 years) who also completed the California Verbal Learning Test. To index white matter integrity, fractional anisotropy values were calculated for bilateral uncinate fasciculus. The results revealed that low anisotropy values corresponded to poor verbal memory, whereas high anisotropy values corresponded to significantly better verbal memory scores. These findings suggest that a greater degree of myelination and cohesiveness of axonal fibers in uncinate fasciculus underlie better verbal memory proficiency in children. PMID:24949818

Schaeffer, David J; Krafft, Cynthia E; Schwarz, Nicolette F; Chi, Lingxi; Rodrigue, Amanda L; Pierce, Jordan E; Allison, Jerry D; Yanasak, Nathan E; Liu, Tianming; Davis, Catherine L; McDowell, Jennifer E

2014-08-20

22

Anatomical Properties of the Arcuate Fasciculus Predict Phonological and Reading Skills in Children  

PubMed Central

For more than a century, neurologists have hypothesized that the arcuate fasciculus carries signals that are essential for language function; however, the relevance of the pathway for particular behaviors is highly controversial. The primary objective of this study was to use diffusion tensor imaging to examine the relationship between individual variation in the microstructural properties of arcuate fibers and behavioral measures of language and reading skills. A second objective was to use novel fiber-tracking methods to reassess estimates of arcuate lateralization. In a sample of 55 children, we found that measurements of diffusivity in the left arcuate correlate with phonological awareness skills and arcuate volume lateralization correlates with phonological memory and reading skills. Contrary to previous investigations that report the absence of the right arcuate in some subjects, we demonstrate that new techniques can identify the pathway in every individual. Our results provide empirical support for the role of the arcuate fasciculus in the development of reading skills.

Yeatman, Jason D.; Dougherty, Robert F.; Rykhlevskaia, Elena; Sherbondy, Anthony J.; Deutsch, Gayle K.; Wandell, Brian A.; Ben-Shachar, Michal

2011-01-01

23

Evaluating the Arcuate Fasciculus With Combined Diffusion-Weighted MRI Tractography and Electrocorticography  

PubMed Central

The conventional model of language-related brain structure describing the arcuate fasciculus as a key white matter tract providing a direct connection between Wernicke’s region and Broca’s area has been called into question. Specifically, the inferior precentral gyrus, possessing both primary motor (Brodmann Area [BA] 4) and premotor cortex (BA 6), has been identified as a potential alternative termination. The authors initially localized cortical sites involved in language using measurement of event-related gamma-activity on electrocorticography (ECoG). The authors then determined whether language-related sites of the temporal lobe were connected, via white matter structures, to the inferior frontal gyrus more tightly than to the precentral gyrus. The authors found that language-related sites of the temporal lobe were far more likely to be directly connected to the inferior precentral gyrus through the arcuate fasciculus. Furthermore, tractography was a significant predictor of frontal language-related ECoG findings. Analysis of an interaction between anatomy and tractography in this model revealed tractrography to have the highest predictive value for language-related ECoG findings of the precentral gyrus. This study failed to support the conventional model of language-related brain structure. More feasible models should include the inferior precentral gyrus as a termination of the arcuate fasciculus. The exact functional significance of direct connectivity between temporal language-related sites and the precentral gyrus requires further study.

Brown, Erik C.; Jeong, Jeong-Won; Muzik, Otto; Rothermel, Robert; Matsuzaki, Naoyuki; Juhasz, Csaba; Sood, Sandeep; Asano, Eishi

2014-01-01

24

What is the role of the uncinate fasciculus? Surgical removal and proper name retrieval.  

PubMed

The functional role of the uncinate fasciculus is still a matter of debate. We examined 44 patients submitted to awake surgery for removal of a left frontal or temporal glioma. In 18 patients, the removal included the uncinate fasciculus. We compared patients with or without removal on a series of neuropsychological tasks, performed at different time intervals: pre-surgery, in the first week after surgery and 3 months after surgery. Functional magnetic resonance and diffusion tensor imaging, fibre-tracking techniques were performed before surgery. At the last examination, patients with uncinate removal were significantly impaired in naming of famous faces and objects as compared with patients without removal. We further divided patients according to the site of the tumour (either frontal or temporal). At the follow-up, patients with a temporal glioma who underwent uncinate removal had the worst loss of performance in famous face naming. In addition, on the same task, the group with a frontal glioma that underwent resection of the frontal part of the uncinate performed significantly worse than the group with a frontal glioma but without uncinate removal. In conclusion, the resection of the uncinate fasciculus, in its frontal or temporal part, has long-lasting consequences for famous face naming. We suggest that this fibre tract is part of a circuitry involved in the retrieval of word form for proper names. Retrieval of conceptual knowledge was intact. PMID:20959310

Papagno, Costanza; Miracapillo, Christiano; Casarotti, Alessandra; Romero Lauro, Leonor J; Castellano, Antonella; Falini, Andrea; Casaceli, Giuseppe; Fava, Enrica; Bello, Lorenzo

2011-02-01

25

Quantification of the spatiotemporal microstructural organization of the human brain association, projection and commissural pathways across the lifespan using diffusion tensor tractography  

PubMed Central

Using diffusion tensor tractography, we quantified the microstructural changes in the association, projection, and commissural compact white matter pathways of the human brain over the lifespan in a cohort of healthy right-handed children and adults aged 6–68 years. In both males and females, the diffusion tensor radial diffusivity of the bilateral arcuate fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, corticospinal, somatosensory tracts, and the corpus callosum followed a U-curve with advancing age; fractional anisotropy in the same pathways followed an inverted U-curve. Our study provides useful baseline data for the interpretation of data collected from patients.

Kamali, Arash; Abid, Humaira; Kramer, Larry A.; Fletcher, Jack M.; Ewing-Cobbs, Linda

2010-01-01

26

Diffusion tensor imaging in autism spectrum disorders: Preliminary evidence of abnormal neural connectivity  

PubMed Central

Objective This study indirectly tested the hypothesis that individuals with autism spectrum disorders (ASDs) have impaired neural connections between the amygdala, fusiform face area, and superior temporal sulcus, key processing nodes of the “social brain.” This would be evidenced by abnormalities in the major fibre tracts known to connect these structures, including the inferior longitudinal fasciculus and inferior fronto-occipital fasciculus. Method Magnetic resonance diffusion tensor imaging was performed on 20 right-handed males (ASD = 10, controls = 10) with a mean age 13.5 ± 4.0 years. Subjects were group-matched according to age, full-scale IQ, handedness, and ethnicity. Fractional anisotropy was used to assess structural integrity of major fibre tracts. Voxel-wise comparison of white matter fractional anisotropy was conducted between groups using ANCOVA adjusting for age, full-scale IQ, and brain volume. Volumes of interest were identified using predetermined probability and cluster thresholds. Follow-up tractography was performed to confirm the anatomic location of all volumes of interest. Results All volumes of interest were regions of lower FA and were observed primarily in pericallosal regions and temporal lobes. As confirmed by tractography, affected white matter structures included the inferior longitudinal fasciculus/inferior fronto-occipital fasciculus, superior longitudinal fasciculus, and corpus callosum/cingulum. Notably, some volumes of interest were adjacent to the fusiform face area, bilaterally, corresponding to involvement of the inferior longitudinal fasciculus. The largest effect sizes were noted for volumes of interest in the right anterior radiation of the corpus callosum/cingulum and right fusiform face area (inferior longitudinal fasciculus). Conclusions This study provides preliminary evidence of impaired neural connectivity in the corpus callosum/cingulum and temporal lobes involving the inferior longitudinal fasciculus/inferior fronto-occipital fasciculus and superior longitudinal fasciculus in ASDs. These findings provide preliminary support for aberrant neural connectivity between the amygdala, fusiform face area, and superior temporal sulcus – temporal lobe structures critical for normal social perception and cognition.

Jou, Roger J.; Jackowski, Andrea P.; Papademetris, Xenophon; Rajeevan, Nallakkandi; Staib, Lawrence H.; Volkmar, Fred R.

2011-01-01

27

'For the benefit of the people': the Dutch translation of the Fasciculus medicinae, Antwerp 1512.  

PubMed

The article deals with the Dutch translation of the Fasciculus medicinae based on the Latin edition, Venice 1495, with the famous woodcuts created in 1494 for the Italian translation of the original Latin edition of 1491. The woodcuts are compared with the Venetian model. New features in the Antwerp edition include the Skeleton and the Zodiac Man, bot originally based on German models. The text also deals with other woodcuts in the Low Countries based on these Venetian illustrations. The Appendices provide a short title catalog of all the editions and translations based on the Venetian edition and a stemma. PMID:19642255

Coppens, Christian

2009-01-01

28

Diffusion Tensor Anisotropy in Adolescents and Adults  

PubMed Central

We acquired diffusion tensor images on 33 normal adults aged 22–64 and 15 adolescents aged 14–21. We assessed relative anisotropy in stereotaxically located regions of interest in the internal capsule, corpus callosum, anterior thalamic radiations, frontal anterior fasciculus, fronto-occipital fasciculus, temporal lobe white matter, cingulum bundle, frontal inferior longitudinal fasciculus, frontal superior longitudinal fasciculus, and optic radiations. All of these structures except the optic radiations, corpus callosum, and frontal inferior longitudinal fasciculus exhibited differences in anisotropy between adolescents and adults. Areas with anisotropy increasing with age included the anterior limb of the internal capsule, superior levels of the frontal superior longitudinal fasciculus and the inferior portion of the temporal white matter. Areas with anisotropy decreasing with age included the posterior limb of the internal capsule, anterior thalamic radiations, fronto-occipital fasciculus, anterior portion of the frontal anterior fasciculus, inferior portion of the frontal superior longitudinal fasciculus, cingulum bundle and superior portion of the temporal axis. Sex differences were found in the majority of areas but were most marked in the cingulum bundle and internal capsule. These results suggest continuing white matter development between adolescence and adulthood.

Schneiderman, Jason S.; Buchsbaum, Monte S.; Haznedar, M. Mehmet; Hazlett, Erin A.; Brickman, Adam M.; Shihabuddin, Lina; Brand, Jesse G.; Torosjan, Yuliya; Newmark, Randall E.; Tang, Cheuk; Aronowitz, Jonathan; Paul-Odouard, Reshmi; Byne, William; Hof, Patrick R.

2009-01-01

29

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

30

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

31

Evidence of Slow Maturation of the Superior Longitudinal Fasciculus in Early Childhood by Diffusion Tensor Imaging  

PubMed Central

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 five years. The result is attributed to slow axonal and/or myelin maturation of this tract, which is believed to be involved in language functions.

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

2009-01-01

32

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

33

Mild Traumatic Brain Injury and Conduction Aphasia from a Close Proximity Blast Resulting in Arcuate Fasciculus Damage Diagnosed on DTI Tractography.  

National Technical Information Service (NTIS)

The authors present a case demonstrating that a blast injury was associated with both conduction aphasia and an abnormality in the left Arcuate Fasciculus (AF) on MR DTI (Diffusion Tensor Imaging). In addition, this study showed the presence of conduction...

A. Kasprisin A. Rosen J. W. Ashford W. Han Y. Zhang

2009-01-01

34

Lakatos Revisited.  

ERIC Educational Resources Information Center

Revisits and reviews Imre Lakatos' ideas on "Falsification and the Methodology of Scientific Research Programmes." Suggests that Lakatos' framework offers an insightful way of looking at the relationship between theory and research that is relevant not only for evaluating research programs in theoretical physics, but in the social sciences as…

Court, Deborah

1999-01-01

35

Increased Brain White Matter Axial Diffusivity Associated with Fatigue, Pain and Hyperalgesia in Gulf War Illness  

PubMed Central

Background Gulf War exposures in 1990 and 1991 have caused 25% to 30% of deployed personnel to develop a syndrome of chronic fatigue, pain, hyperalgesia, cognitive and affective dysfunction. Methods Gulf War veterans (n?=?31) and sedentary veteran and civilian controls (n?=?20) completed fMRI scans for diffusion tensor imaging. A combination of dolorimetry, subjective reports of pain and fatigue were correlated to white matter diffusivity properties to identify tracts associated with symptom constructs. Results Gulf War Illness subjects had significantly correlated fatigue, pain, hyperalgesia, and increased axial diffusivity in the right inferior fronto-occipital fasciculus. ROC generated thresholds and subsequent binary regression analysis predicted CMI classification based upon axial diffusivity in the right inferior fronto-occipital fasciculus. These correlates were absent for controls in dichotomous regression analysis. Conclusion The right inferior fronto-occipital fasciculus may be a potential biomarker for Gulf War Illness. This tract links cortical regions involved in fatigue, pain, emotional and reward processing, and the right ventral attention network in cognition. The axonal neuropathological mechanism(s) explaining increased axial diffusivity may account for the most prominent symptoms of Gulf War Illness.

Rayhan, Rakib U.; Stevens, Benson W.; Timbol, Christian R.; Adewuyi, Oluwatoyin; Walitt, Brian; VanMeter, John W.; Baraniuk, James N.

2013-01-01

36

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

37

Sex differences of uncinate fasciculus structural connectivity in individuals with conduct disorder.  

PubMed

Conduct disorder (CD) is one of the most common behavior disorders in adolescents, such as impulsivity, aggression, and running from school. Males are more likely to develop CD than females, and two previous diffusion tensor imaging (DTI) studies have demonstrated abnormal microstructural integrity in the uncinate fasciculus (UF) in boys with CD compared to a healthy control group. However, little is known about changes in the UF in females with CD. In this study, the UF was illustrated by tractography; then, the fractional anisotropy (FA), axial diffusivity, mean diffusion, radial diffusivity (RD), and the length and number of the UF fiber bundles were compared between male and female patients with CD and between female patients with CD and female healthy controls, as well as between males with CD and healthy males. We found that males with CD showed significantly higher FA of the bilateral UF and significantly lower RD of the left UF when comparing with females with CD. Meanwhile, significantly higher FA and lower RD of the bilateral UF were also found in boys with CD relative to the male healthy controls. Our results replicated previous reports that the microstructural integrity of the UF was abnormal in boys with CD. Additionally, our results demonstrated significant gender effects on the UF of patients with CD, which may indicate why boys have higher rates of conduct problems than girls. PMID:24829912

Zhang, Jibiao; Gao, Junling; Shi, Huqing; Huang, Bingsheng; Wang, Xiang; Situ, Weijun; Cai, Weixiong; Yi, Jinyao; Zhu, Xiongzhao; Yao, Shuqiao

2014-01-01

38

Individual differences in crossmodal brain activity predict arcuate fasciculus connectivity in developing readers.  

PubMed

Crossmodal integration of auditory and visual information, such as phonemes and graphemes, is a critical skill for fluent reading. Previous work has demonstrated that white matter connectivity along the arcuate fasciculus (AF) is predicted by reading skill and that crossmodal processing particularly activates the posterior STS (pSTS). However, the relationship between this crossmodal activation and white matter integrity has not been previously reported. We investigated the interrelationship of crossmodal integration, both in terms of behavioral performance and pSTS activity, with AF tract coherence using a rhyme judgment task in a group of 47 children with a range of reading abilities. We demonstrate that both response accuracy and pSTS activity for crossmodal (auditory-visual) rhyme judgments was predictive of fractional anisotropy along the left AF. Unimodal (auditory-only or visual-only) pSTS activity was not significantly related to AF connectivity. Furthermore, activity in other reading-related ROIs did not show the same AV-only AF coherence relationship, and AV pSTS activity was not related to connectivity along other language-related tracts. This study is the first to directly show that crossmodal brain activity is specifically related to connectivity in the AF, supporting its role in phoneme-grapheme integration ability. More generally, this study helps to define an interdependent neural network for reading-related integration. PMID:24456399

Gullick, Margaret M; Booth, James R

2014-07-01

39

Sex Differences of Uncinate Fasciculus Structural Connectivity in Individuals with Conduct Disorder  

PubMed Central

Conduct disorder (CD) is one of the most common behavior disorders in adolescents, such as impulsivity, aggression, and running from school. Males are more likely to develop CD than females, and two previous diffusion tensor imaging (DTI) studies have demonstrated abnormal microstructural integrity in the uncinate fasciculus (UF) in boys with CD compared to a healthy control group. However, little is known about changes in the UF in females with CD. In this study, the UF was illustrated by tractography; then, the fractional anisotropy (FA), axial diffusivity, mean diffusion, radial diffusivity (RD), and the length and number of the UF fiber bundles were compared between male and female patients with CD and between female patients with CD and female healthy controls, as well as between males with CD and healthy males. We found that males with CD showed significantly higher FA of the bilateral UF and significantly lower RD of the left UF when comparing with females with CD. Meanwhile, significantly higher FA and lower RD of the bilateral UF were also found in boys with CD relative to the male healthy controls. Our results replicated previous reports that the microstructural integrity of the UF was abnormal in boys with CD. Additionally, our results demonstrated significant gender effects on the UF of patients with CD, which may indicate why boys have higher rates of conduct problems than girls.

Zhang, Jibiao; Gao, Junling; Shi, Huqing; Huang, Bingsheng; Wang, Xiang; Situ, Weijun; Cai, Weixiong; Yi, Jinyao; Zhu, Xiongzhao; Yao, Shuqiao

2014-01-01

40

Superior longitudinal fasciculus and cognitive dysfunction in adolescents born preterm and at term  

PubMed Central

Aim To understanding the relation between cognition and white matter structure in adolescents born preterm without obvious brain injury. Methods Thirty-two adolescents were selected based on birth risk (Full-term: M:F=8:5, Median (Interquartile Range) Age=16.1(.8); Low-risk preterm: M:F=4:5, Age=16.0(.3); High-risk preterm: M:F=3:7, Age=16.2(1.2)) and reading ability (Good-readers: M:F=3:8, Age=16.0(.6); Average-readers, M:F=6:3, Age=16.8(1.0); Poor-readers M:F=6:6, Age=16.0(.5)) from a longitudinal study on child development. Preterm birth was defined as a gestational age ?36 weeks and a birth weight <=1600g. All participants demonstrated normal clinical neuroimaging. We examined fractional anisotropy (FA), radial diffusivity and volume of three major white matter fasciculi. The relations between structural measures and birth risk, hemisphere and cognitive ability (attention, lexical and sublexical decoding, auditory phonological awareness and processing speed) were analyzed using mixed-model regression. Results Left superior longitudinal fasciculus (SLF) FA and radial diffusivity was related to reading-related skills while right SLF FA was related to attention skills. SLF volume decreased as these skills declined for adolescents born preterm, but not those born at term. Interpretation The relation between cognitive skills and SLF volume suggests that cryptic white matter injury may exist, possibly related to oligodendrocyte or axonal loss, despite normal clinical neuroimaging in adolescents born preterm.

Frye, Richard E.; Hasan, Khader; Malmberg, Benjamin; deSouza, Laura; Swank, Paul; Smith, Karen; Landry, Susan

2010-01-01

41

White matter alterations in temporal lobe epilepsy  

NASA Astrophysics Data System (ADS)

In This study, we used Fractional anisotropy (FA), mean diffusivity (D), parallel diffusivity (D//) and perpendicular diffusivity (D), to localize the regions where occur axonal lesion and demyelization. TBSS was applied to analyze the FA data. After, the regions with alteration were studied with D, D// and D maps. Patients exhibited widespread degradation of FA. With D, D// and D maps analysis we found alterations in corpus callosum, corticospinal tract, fornix, internal capsule, corona radiate, Sagittal stratum, cingulum, fronto-occipital fasciculus and uncinate fasciculus. Our results are consistent with the hypothesis that exist demyelization and axonal damage in patients with TLE.

Diniz, P. B.; Salmon, C. E.; Velasco, T. R.; Sakamoto, A. C.; Leite, J. P.; Santos, A. C.

2011-03-01

42

Analysis of the subcomponents and cortical terminations of the perisylvian superior longitudinal fasciculus: a fiber dissection and DTI tractography study.  

PubMed

The anatomy of the perisylvian component of the superior longitudinal fasciculus (SLF) has recently been reviewed by numerous diffusion tensor imaging tractography (DTI) studies. However, little is known about the exact cortical terminations of this tract. The aim of the present work is to isolate the different subcomponents of this tract with fiber dissection and DTI tractography, and to identify the exact cortical connections. Twelve postmortem human hemispheres (6 right and 6 left) were dissected using the cortex-sparing fiber dissection. In addition, three healthy brains were analyzed using DTI-based tractography software. The different components of the perisylvian SLF were isolated and the fibers were followed until the cortical terminations. Three segments of the perisylvian SLF were identified: (1) anterior segment, connecting the supramarginal gyrus and superior temporal gyrus with the precentral gyrus, (2) posterior segment, connecting the posterior portion of the middle temporal gyrus with the angular gyrus, and (3) long segment of the arcuate fasciculus that connects the middle and inferior temporal gyri with the precentral gyrus and posterior portion of the inferior and middle frontal gyri. In the present study, three different components of the perisylvian SLF were identified. For the first time, our dissections revealed that each component was connected to a specific cortical area within the frontal, parietal and temporal lobes. By accurately depicting not only the trajectory but also cortical connections of this bundle, it is possible to develop new insights into the putative functional role of this tract. PMID:22422148

Martino, Juan; De Witt Hamer, Philip C; Berger, Mitchel S; Lawton, Michael T; Arnold, Christine M; de Lucas, Enrique Marco; Duffau, Hugues

2013-01-01

43

decays revisited  

NASA Astrophysics Data System (ADS)

We revisit the determination of ? S (m {/? 2}) using a fit to inclusive ? hadronic spectral moments in light of (1) the recent calculation of the fourth-order perturbative coefficient K 4 in the expansion of the Adler function, (2) new precision measurements from BABAR of e+e- annihilation cross sections, which decrease the uncertainty in the separation of vector and axial-vector spectral functions, and (3) improved results from BABAR and Belle on ? branching fractions involving kaons. We estimate that the fourth-order perturbative prediction reduces the theoretical uncertainty, introduced by the truncation of the series, by 20% with respect to earlier determinations. We discuss to some detail the perturbative prediction of two different methods: fixed-order perturbation theory (FOPT) and contour-improved perturbative theory (CIPT). The corresponding theoretical uncertainties are studied at the ? and Z mass scales. The CIPT method is found to be more stable with respect to the missing higher order contributions and to renormalization scale variations. It is also shown that FOPT suffers from convergence problems along the complex integration contour. Nonperturbative contributions extracted from the most inclusive fit are small, in agreement with earlier determinations. Systematic effects from quark-hadron duality violation are estimated with simple models and found to be within the quoted systematic errors. The fit based on CIPT gives ? S (m {/? 2})=0.344±0.005±0.007, where the first error is experimental and the second theoretical. After evolution to M Z we obtain ? S (M {/Z 2})=0.1212±0.0005±0.0008±0.0005, where the errors are respectively experimental, theoretical and due to the evolution. The result is in agreement with the corresponding N3LO value derived from essentially the Z width in the global electroweak fit. The ? S (M {/Z 2}) determination from ? decays is the most precise one to date.

Davier, M.; Descotes-Genon, S.; Höcker, A.; Malaescu, B.; Zhang, Z.

2008-08-01

44

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

45

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

46

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

47

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.

48

Relations between white matter maturation and reaction time in childhood.  

PubMed

White matter matures with age and is important for the efficient transmission of neuronal signals. Consequently, white matter growth may underlie the development of cognitive processes important for learning, including the speed of information processing. To dissect the relationship between white matter structure and information processing speed, we administered a reaction time task (finger abduction in response to visual cue) to 27 typically developing, right-handed children aged 4 to 13. Magnetoencephalography and Diffusion Tensor Imaging were used to delineate white matter connections implicated in visual-motor information processing. Fractional anisotropy (FA) and radial diffusivity (RD) of the optic radiation in the left hemisphere, and FA and mean diffusivity (MD) of the optic radiation in the right hemisphere changed significantly with age. MD and RD decreased with age in the right inferior fronto-occipital fasciculus, and bilaterally in the cortico-spinal tracts. No age-related changes were evident in the inferior longitudinal fasciculus. FA of the cortico-spinal tract in the left hemisphere and MD of the inferior fronto-occipital fasciculus of the right hemisphere contributed uniquely beyond the effect of age in accounting for reaction time performance of the right hand. Our findings support the role of white matter maturation in the development of information processing speed. PMID:24168858

Scantlebury, Nadia; Cunningham, Todd; Dockstader, Colleen; Laughlin, Suzanne; Gaetz, William; Rockel, Conrad; Dickson, Jolynn; Mabbott, Donald

2014-01-01

49

Differences in white matter reflect atypical developmental trajectory in autism: A Tract-based Spatial Statistics study.  

PubMed

Autism is a neurodevelopmental disorder in which white matter (WM) maturation is affected. We assessed WM integrity in 16 adolescents and 14 adults with high-functioning autism spectrum disorder (ASD) and in matched neurotypical controls (NT) using diffusion weighted imaging and Tract-based Spatial Statistics. Decreased fractional anisotropy (FA) was observed in adolescents with ASD in tracts involved in emotional face processing, language, and executive functioning, including the inferior fronto-occipital fasciculus and the inferior and superior longitudinal fasciculi. Remarkably, no differences in FA were observed between ASD and NT adults. We evaluated the effect of age on WM development across the entire age range. Positive correlations between FA values and age were observed in the right inferior fronto-occipital fasciculus, the left superior longitudinal fasciculus, the corpus callosum, and the cortical spinal tract of ASD participants, but not in NT participants. Our data underscore the dynamic nature of brain development in ASD, showing the presence of an atypical process of WM maturation, that appears to normalize over time and could be at the basis of behavioral improvements often observed in high-functioning autism. PMID:24179736

Bakhtiari, Reyhaneh; Zürcher, Nicole R; Rogier, Ophélie; Russo, Britt; Hippolyte, Loyse; Granziera, Cristina; Araabi, Babak Nadjar; Nili Ahmadabadi, Majid; Hadjikhani, Nouchine

2012-01-01

50

Differences in white matter reflect atypical developmental trajectory in autism: A Tract-based Spatial Statistics study?  

PubMed Central

Autism is a neurodevelopmental disorder in which white matter (WM) maturation is affected. We assessed WM integrity in 16 adolescents and 14 adults with high-functioning autism spectrum disorder (ASD) and in matched neurotypical controls (NT) using diffusion weighted imaging and Tract-based Spatial Statistics. Decreased fractional anisotropy (FA) was observed in adolescents with ASD in tracts involved in emotional face processing, language, and executive functioning, including the inferior fronto-occipital fasciculus and the inferior and superior longitudinal fasciculi. Remarkably, no differences in FA were observed between ASD and NT adults. We evaluated the effect of age on WM development across the entire age range. Positive correlations between FA values and age were observed in the right inferior fronto-occipital fasciculus, the left superior longitudinal fasciculus, the corpus callosum, and the cortical spinal tract of ASD participants, but not in NT participants. Our data underscore the dynamic nature of brain development in ASD, showing the presence of an atypical process of WM maturation, that appears to normalize over time and could be at the basis of behavioral improvements often observed in high-functioning autism.

Bakhtiari, Reyhaneh; Zurcher, Nicole R.; Rogier, Ophelie; Russo, Britt; Hippolyte, Loyse; Granziera, Cristina; Araabi, Babak Nadjar; Nili Ahmadabadi, Majid; Hadjikhani, Nouchine

2012-01-01

51

Monkey to human comparative anatomy of the frontal lobe association tracts.  

PubMed

The greater expansion of the frontal lobes along the phylogeny scale has been interpreted as the signature of evolutionary changes underlying higher cognitive abilities in humans functions in humans. However, it is unknown how an increase in number of gyri, sulci and cortical areas in the frontal lobe have coincided with a parallel increase in connectivity. Here, using advanced tractography based on spherical deconvolution, we produced an atlas of human frontal association connections that we compared with axonal tracing studies of the monkey brain. We report several similarities between human and monkey in the cingulum, uncinate, superior longitudinal fasciculus, frontal aslant tract and orbito-polar tract. These similarities suggest to preserved functions across anthropoids. In addition, we found major differences in the arcuate fasciculus and the inferior fronto-occipital fasciculus. These differences indicate possible evolutionary changes in the connectional anatomy of the frontal lobes underlying unique human abilities. PMID:22088488

Thiebaut de Schotten, Michel; Dell'Acqua, Flavio; Valabregue, Romain; Catani, Marco

2012-01-01

52

White matter abnormalities in adolescents with generalized anxiety disorder: a diffusion tensor imaging study  

PubMed Central

Background Previous neuroimaging studies have suggested an abnormal neural circuitry of emotion regulation including the amygdala and prefrontal cortex in both adult and adolescent generalized anxiety disorder (GAD) patients. Aberrant integrity of white matter in this neural circuitry has been verified in adult GAD patients. White matter abnormalities in adolescent GAD patients have not been detected. Methods Twenty-five adolescents with GAD and 24 healthy controls underwent a diffusion tensor imaging scan. Fractional anisotropy (FA) was compared between groups with a voxel-wise Tract-Based Spatial Statistics (TBSS) analysis method. Results Compared with healthy controls, adolescents with GAD showed significantly reduced FA in bilateral uncinate fasciculus, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, and corona radiata. Conclusions The findings in the present study suggest a neural basis of emotion dysregulation in adolescent GAD patients.

2014-01-01

53

Revisiting Teachers as Learners  

ERIC Educational Resources Information Center

This article revisits the concept of teachers as learners within the context of radical changes that have taken place within the education system in England over the past 25 years. The concept of "professional courage" is discussed and examined in relation to questions and issues raised by Paulo Freire in a series of letters to teachers (1997).…

Thomson, Liz

2008-01-01

54

Revisiting the Rhetorical Curriculum  

ERIC Educational Resources Information Center

The aim of the special strand on "Revisiting the rhetorical curriculum" is to explore the educational potential of a new rhetorical perspective, specifically in relation to different traditions within educational and rhetorical studies. This implies that we do not only look at education "in" rhetoric, but that we position education also "as" a…

Rutten, Kris; Soetaert, Ronald

2012-01-01

55

Revisiting Curriculum Potential  

ERIC Educational Resources Information Center

This article analyzes the notion of curriculum potential by revisiting the ideas of Miriam Ben-Peretz and Joseph Schwab. Invoking the German "Didaktik" tradition and by way of a curriculum-making framework, the paper argues that interpreting curriculum materials for curriculum potential requires a careful analysis and unpacking of the meanings and…

Deng, Zongyi

2011-01-01

56

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

57

Superresolution Imaging—Revisited  

Microsoft Academic Search

Methods for synthesizing and recovering signal features below the diffraction limit are revisited and interpreted as instances of a single unifying principle. Based on the review of the Rayleigh resolution limit and Abbe's theory of the microscope two distinct strategies can be distinguished: The first uses suitable encoding methods to increase the signal bandwidth passed through the imaging system at

Markus E. Testorf; Michael A. Fiddy

2010-01-01

58

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

59

Clinical ethics revisited  

PubMed Central

A decade ago, we reviewed the field of clinical ethics; assessed its progress in research, education, and ethics committees and consultation; and made predictions about the future of the field. In this article, we revisit clinical ethics to examine our earlier observations, highlight key developments, and discuss remaining challenges for clinical ethics, including the need to develop a global perspective on clinical ethics problems.

Singer, Peter A; Pellegrino, Edmund D; Siegler, Mark

2001-01-01

60

Clinical ethics revisited  

Microsoft Academic Search

A decade ago, we reviewed the field of clinical ethics; assessed its progress in research, education, and ethics committees and consultation; and made predictions about the future of the field. In this article, we revisit clinical ethics to examine our earlier observations, highlight key developments, and discuss remaining challenges for clinical ethics, including the need to develop a global perspective

Peter A Singer; Edmund D Pellegrino; Mark Siegler

2001-01-01

61

Revisiting the learning organisation  

Microsoft Academic Search

The concept of the learning organisation is now established, yet there are not many organisations that claim to be learning organisations. Revisits the concept of the learning organisation to illustrate the key attributes. Suggests some of the key requirements to make the transformation into a learning organisation and highlights the benefits that can accrue.

Simon Evans

1998-01-01

62

Cerebral white matter deficiencies in pedophilic men.  

PubMed

The present investigation sought to identify which brain regions distinguish pedophilic from nonpedophilic men, using unbiased, automated analyses of the whole brain. T1-weighted magnetic resonance images (MRIs) were acquired from men who demonstrated illegal or clinically significant sexual behaviors or interests (n = 65) and from men who had histories of nonsexual offenses but no sexual offenses (n = 62). Sexual interest in children was assessed by participants' admissions of pedophilic interest, histories of committing sexual offenses against children, and psychophysiological responses in the laboratory to erotic stimuli depicting children or adults. Automated parcellation of the MRIs revealed significant negative associations between pedophilia and white matter volumes of the temporal and parietal lobes bilaterally. Voxel-based morphometry corroborated the associations and indicated that the regions of lower white matter volumes followed, and were limited to, two major fiber bundles: the superior fronto-occipital fasciculus and the right arcuate fasciculus. No significant differences were found in grey matter or in cerebrospinal fluid (CSF). Because the superior fronto-occipital and arcuate fasciculi connect the cortical regions that respond to sexual cues, these results suggest (1) that those cortical regions operate as a network for recognizing sexually relevant stimuli and (2) that pedophilia results from a partial disconnection within that network. PMID:18039544

Cantor, James M; Kabani, Noor; Christensen, Bruce K; Zipursky, Robert B; Barbaree, Howard E; Dickey, Robert; Klassen, Philip E; Mikulis, David J; Kuban, Michael E; Blak, Thomas; Richards, Blake A; Hanratty, M Katherine; Blanchard, Ray

2008-02-01

63

The left superior longitudinal fasciculus within the primary sensory area of inferior parietal lobe plays a role in dysgraphia of kana omission within sentences.  

PubMed

Functional neurological changes after surgery combined with diffusion tensor imaging (DTI) tractography can directly provide evidence of anatomical localization of brain function. Using these techniques, a patient with dysgraphia before surgery was analyzed at our hospital in 2011. The patient showed omission of kana within sentences before surgery, which improved after surgery. The brain tumor was relatively small and was located within the primary sensory area (S1) of the inferior parietal lobe (IPL). DTI tractography before surgery revealed compression of the branch of the superior longitudinal fasciculus (SLF) by the brain tumor. These results suggest that the left SLF within the S1 of IPL plays a role in the development of dysgraphia of kana omission within sentences. PMID:22713399

Shinoura, Nobusada; Midorikawa, Akira; Onodera, Toshiyuki; Yamada, Ryozi; Tabei, Yusuke; Onda, Yasumitsu; Itoi, Chihiro; Saito, Seiko; Yagi, Kazuo

2012-01-01

64

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

65

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

PubMed

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 cortex (vPMC) in the right and left hemispheres (RH, LH). These pathways have previously been studied in the LH, but not in the RH. Only 1/8 subjects showed fiber tracts between PTr and hAF in the RH (also, only 1/8 in the LH). In contrast to PTr, 5/8 subjects showed fiber tracts between POp and hAF in the RH (8/8 in the LH). Fiber tracts for vPMC were similar to those of POp, where 7/8 subjects showed fiber tracts between vPMC and hAF in the RH (8/8 in the LH). Our designated hAF could have included some of the superior longitudinal fasciculus (SLF) III, because it is difficult to separate the two fiber bundles. The SLF III has been previously reported to connect supramarginal gyrus with POp and vPMC in the LH. Thus, although the present DTI study showed almost no pathways between PTr and hAF in the RH (and in the LH), robust pathways were observed between POp and/or vPMC with hAF in the RH (and in LH). These results replicate previous studies for the LH, but are new, for the RH. They could contribute to better understanding of recovery in aphasia. PMID:20438853

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

2010-08-15

66

Patterns of dysgraphia in primary progressive aphasia compared to post-stroke aphasia.  

PubMed

We report patterns of dysgraphia in participants with primary progressive aphasia that can be explained by assuming disruption of one or more cognitive processes or representations in the complex process of spelling. These patterns are compared to those described in participants with focal lesions (stroke). Using structural imaging techniques, we found that damage to the left extrasylvian regions, including the uncinate, inferior fronto-occipital fasciculus, and sagittal stratum (including geniculostriate pathway and inferior longitudinal fasciculus), as well as other deep white and grey matter structures, was significantly associated with impairments in access to orthographic word forms and semantics (with reliance on phonology-to-orthography to produce a plausible spelling in the spelling to dictation task). These results contribute not only to our understanding of the patterns of dysgraphia following acquired brain damage but also the neural substrates underlying spelling. PMID:22713396

Faria, Andreia V; Crinion, Jenny; Tsapkini, Kyrana; Newhart, Melissa; Davis, Cameron; Cooley, Shannon; Mori, Susumu; Hillis, Argye E

2013-01-01

67

Patterns of Dysgraphia in Primary Progressive Aphasia Compared to Post-Stroke Aphasia  

PubMed Central

We report patterns of dysgraphia in participants with primary progressive aphasia that can be explained by assuming disruption of one or more cognitive processes or representations in the complex process of spelling. These patterns are compared to those described in participants with focal lesions (stroke). Using structural imaging techniques, we found that damage to the left extrasylvian regions, including the uncinate, inferior fronto-occipital fasciculus, and sagittal stratum (including geniculostriate pathway and inferior longitudinal fasciculus), as well as other deep white and grey matter structures, was significantly associated with impairments in access to orthographic word forms and semantics (with reliance on phonology-to-orthography to produce a plausible spelling in the spelling to dictation task). These results contribute not only to our understanding of the patterns of dysgraphia following acquired brain damage but also the neural substrates underlying spelling.

Faria, Andreia V.; Crinion, Jenny; Tsapkini, Kyrana; Newhart, Melissa; Davis, Cameron; Cooley, Shannon; Mori, Susumu; Hillis, Argye E.

2013-01-01

68

Temporal Dynamic Controllability Revisited  

NASA Technical Reports Server (NTRS)

An important issue for temporal planners is the ability to handle temporal uncertainty. We revisit the question of how to determine whether a given set of temporal requirements are feasible in the light of uncertain durations of some processes. In particular, we consider how best to determine whether a network is Dynamically Controllable, i.e., whether a dynamic strategy exists for executing the network that is guaranteed to satisfy the requirements. Previous work has shown the existence of a pseudo-polynomial algorithm for testing Dynamic Controllability. Here, we greatly simplify the previous framework, and present a true polynomial algorithm with a cutoff based only on the number of nodes.

Morris, Paul H.; Muscettola, Nicola

2005-01-01

69

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

2013-10-01

70

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

2013-05-15

71

Association of dorsal inferior frontooccipital fasciculus fibers in the deep parietal lobe with both reading and writing processes: a brain mapping study.  

PubMed

Alexia and agraphia are disorders common to the left inferior parietal lobule, including the angular and supramarginal gyri. However, it is still unclear how these cortical regions interact with other cortical sites and what the most important white matter tracts are in relation to reading and writing processes. Here, the authors present the case of a patient who underwent an awake craniotomy for a left inferior parietal lobule glioma using direct cortical and subcortical electrostimulation. The use of subcortical stimulation allowed identification of the specific white matter tracts associated with reading and writing. These tracts were found as portions of the dorsal inferior frontooccipital fasciculus (IFOF) fibers in the deep parietal lobe that are responsible for connecting the frontal lobe to the superior parietal lobule. These findings are consistent with previous diffusion tensor imaging tractography and functional MRI studies, which suggest that the IFOF may play a role in the reading and writing processes. This is the first report of transient alexia and agraphia elicited through intraoperative direct subcortical electrostimulation, and the findings support the crucial role of the IFOF in reading and writing. PMID:24655122

Motomura, Kazuya; Fujii, Masazumi; Maesawa, Satoshi; Kuramitsu, Shunichiro; Natsume, Atsushi; Wakabayashi, Toshihiko

2014-07-01

72

Curvaton dynamics revisited  

NASA Astrophysics Data System (ADS)

We revisit the dynamics of the curvaton in detail taking account of effects from thermal environment, effective potential and decay/dissipation rate for general field values and couplings. We also consider the curvature perturbation generated through combinations of various effects: large scale modulation of the oscillation epoch, the effective dissipation rate and the timing at which the equation of state changes. In particular, we find that it tends to be difficult to explain the observed curvature perturbation by the curvaton mechanism without producing too large non-Gaussianity if the curvaton energy density is dissipated through thermal effects. In particular, we find that if the renormalizable coupling between the curvaton and light elements is larger than the critical value ~ (mphi/Mpl)1/2, the curvaton is soon dissipated away almost regardless of its initial energy density, contrary to the standard perturbative decay. Therefore, the interaction between them should be suppressed in order for the curvaton to survive the thermal dissipation.

Mukaida, Kyohei; Nakayama, Kazunori; Takimoto, Masahiro

2014-06-01

73

Jaccoud's arthropathy revisited.  

PubMed

Jaccoud's arthropathy is a chronic, non erosive, rheumatoid-like deformity of the hands associated with rheumatic fever and systemic lupus erythematosus (SLE). This deforming arthropathy may present difficulties in differentiating SLE from rheumatoid arthritis (RA). We present a case of a 43-year-old woman who was initially diagnosed with Sjogren's syndrome and rheumatoid arthritis (RA), and several years later, with SLE. The diagnosis of RA was based mainly on the presence of hands deformities. On evaluation she had reducible hands deformities and had no radiographic evidence of joint destruction; thus joint deformities were not consistent with RA but to Jaccoud's arthropathy associated with SLE. Here, we revisit Jaccoud's arthropathy and highlight the importance of a careful joint examination in the assessment of rheumatic diseases. PMID:19227718

Martínez, David

2008-01-01

74

White Matter Microstructure in Attention-Deficit/Hyperactivity Disorder Subjects and Their Siblings  

PubMed Central

Objective Previous voxel-based and regions-of-interest (ROI)-based diffusion tensor imaging (DTI) studies have found above-normal mean diffusivity (MD) and below-normal fractional anisotropy (FA) in subjects with attention-deficit/hyperactivity disorder (ADHD). However, findings remain mixed and few studies have examined the contribution of ADHD familial liability to white matter microstructure. Method We used refined DTI tractography methods to examine MD, FA, axial diffusivity (AD) and radial diffusivity (RD) of the anterior thalamic radiation, cingulum, corticospinal tract, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, forceps major, forceps minor, superior longitudinal fasciculus and uncinate fasciculus in children and adolescents with ADHD (n = 56), unaffected siblings of ADHD probands (n = 31) and healthy controls (n = 17). Results Subjects with ADHD showed significantly higher MD than controls in the anterior thalamic radiation, forceps minor, and superior longitudinal fasciculus. Unaffected siblings of subjects with ADHD displayed similar differences in MD as subjects with ADHD. While none of the tested tracts showed a significant effect of FA, the tracts with elevated MD likewise displayed elevated AD in both subjects with ADHD and unaffected siblings. Differences in RD between subjects with ADHD, unaffected siblings and controls were not as widespread as differences in MD and AD. Conclusion Our findings suggest that disruptions in white matter microstructure occur in several large white matter pathways in association with ADHD and indicate a familial liability for the disorder. Furthermore, MD may reflect these abnormalities more sensitively than FA.

Lawrence, Katherine E.; Levitt, Jennifer G.; Loo, Sandra K.; Ly, Ronald; Yee, Victor; O'Neill, Joseph; Alger, Jeffry; Narr, Katherine L.

2013-01-01

75

Origin and neurochemical properties of bulbospinal neurons projecting to the rat lumbar spinal cord via the medial longitudinal fasciculus and caudal ventrolateral medulla  

PubMed Central

Bulbospinal systems (BS) originate from various regions of the brainstem and influence spinal neurons by classical synaptic and modulatory mechanisms. Our aim was to determine the brainstem locations of cells of origin of BS pathways passing through the medial longitudinal fasciculus (MLF) and the caudal ventrolateral medulla (CVLM). We also examined the transmitter content of spinal terminations of the CVLM pathway. Six adult rats received Fluorogold (FG) injections to the right intermediate gray matter of the lumbar cord (L1–L2) and the b-subunit of cholera toxin (CTb) was injected either into the MLF or the right CVLM (3 animals each). Double-labeled cells were identified within brainstem structures with confocal microscopy and mapped onto brainstem diagrams. An additional 3 rats were injected with CTb in the CVLM to label axon terminals in the lumbar spinal cord. Double-labeled cells projecting via the MLF or CVLM were found principally in reticular regions of the medulla and pons but small numbers of cells were also located within the midbrain. CVLM projections to the lumbar cord were almost exclusively ipsilateral and concentrated within the intermediate gray matter. Most (62%) of terminals were immunoreactive for the vesicular glutamate transporter 2 while 23% contained the vesicular GABA transporter. The inhibitory subpopulation was glycinergic, GABAergic or contained both transmitters. The proportions of excitatory and inhibitory axons projecting via the CVLM to the lumbar cord are similar to those projecting via the MLF. Unlike the MLF pathway, CVLM projections are predominantly ipsilateral and concentrated within intermediate gray but do not extend into motor nuclei or laminia VIII. Terminations of the CVLM pathway are located in a region of the gray matter that is rich in premotor interneurons; thus its primary function may be to coordinate activity of premotor networks.

Huma, Zilli; Du Beau, Amy; Brown, Christina; Maxwell, David J.

2014-01-01

76

Reduced fractional anisotropy in the uncinate fasciculus in patients with major depression carrying the met-allele of the Val66Met brain-derived neurotrophic factor genotype.  

PubMed

Experimental studies support a neurotrophic hypothesis of major depressive disorder (MDD). The aim of this study was to determine the effect of Val66Met brain-derived neurotrophic factor (BDNF) polymorphism on the white matter fiber tracts connecting hippocampus and amygdala with the prefrontal lobe in a sample of patients with MDD and healthy controls. Thirty-seven patients with MDD and 42 healthy volunteers were recruited. Diffusion tensor imaging (DTI) data with 61 diffusion directions were obtained with MRI 3 Tesla scanner. Deterministic tractography was applied with ExploreDTI and Val66Met BDNF SNP (rs6265) was genotyped. Fiber tracts connecting the hippocampus and amygdala with the prefrontal lobe, namely uncinate fasciculus (UF), fornix, and cingulum were analyzed. A significant interaction was found in the UF between BDNF alleles and diagnosis. Patients carrying the BDNF met-allele had smaller fractional anisotropy (FA) in the UF compared to those patients homozygous for val-allele and compared to healthy subjects carrying the met-allele. A significant three-way interaction was detected between region of the cingulum (dorsal, rostral, and parahippocampal regions), brain hemisphere and BDNF genotype. Larger FA was detectable in the left rostral cingulum for met-allele carriers when compared to val/val alelle carriers. We provide evidence for the importance of the neurotrophic involvement in limbic and prefrontal connections. The met-allele of the BDNF polymorphism seems to render subjects more vulnerable for dysfunctions associated with the UF, a tract known to be related to negative emotional-cognitive processing bias, declarative memory problems, and autonoetic self awareness. PMID:22585743

Carballedo, A; Amico, F; Ugwu, I; Fagan, A J; Fahey, C; Morris, D; Meaney, J F; Leemans, A; Frodl, T

2012-07-01

77

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

78

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

79

The "Mushroom Cloud" Demonstration Revisited  

ERIC Educational Resources Information Center

A revisitation of the classical "mushroom cloud" demonstration is described. Instead of aniline and benzoyl peroxide, the proposed reaction involves household chemicals such as alpha-pinene (turpentine oil) and trichloroisocyanuric acid ("Trichlor") giving an impressive demonstration of oxidation and combustion reactions that…

Panzarasa, Guido; Sparnacci, Katia

2013-01-01

80

The tallest column — optimality revisited  

Microsoft Academic Search

The problem of the optimal design of the tallest unloaded column under selfweight is revisited with a view towards clarifying the optimality of the design proposed by Keller and Niordson (The Tallest Column, J. Math. Mech. 16 (1966), pp. 433–446). The height of the tallest column is related to the first eigenvalue of a Sturm-Liouville operator. Since the operator associated

C. Maeve McCarthy

1999-01-01

81

LTL Generalized Model Checking Revisited  

Microsoft Academic Search

Given a 3-valued abstraction of a program (possibly generated using static program analysis and predicate abstraction) and a te mporal logic formula, generalized model checking (GMC) checks whether there exists a concretiza- tion of that abstraction that satisfies the formula. In this p aper, we revisit gen- eralized model checking for linear time (LTL) properties. First, we show that LTL

Patrice Godefroid; Nir Piterman

2009-01-01

82

Benjamin franklin and mesmerism, Revisited  

Microsoft Academic Search

The authors revisit and update their previous historiographical note (McConkey & Perry, 1985) on Benjamin Franklin's involvement with and investigation of animal magnetism or mesmerism. They incorporate more recent literature and offer additional comment about Franklin's role in and views about mesmerism. Franklin had a higher degree of personal involvement with and a more detailed opinion of mesmerism than has

Kevin M. McConkey; Campbell Perry

2002-01-01

83

Diffusion orientation transform revisited.  

PubMed

Diffusion orientation transform (DOT) is a powerful imaging technique that allows the reconstruction of the microgeometry of fibrous tissues based on diffusion MRI data. The three main error sources involving this methodology are the finite sampling of the q-space, the practical truncation of the series of spherical harmonics and the use of a mono-exponential model for the attenuation of the measured signal. In this work, a detailed mathematical description that provides an extension to the DOT methodology is presented. In particular, the limitations implied by the use of measurements with a finite support in q-space are investigated and clarified as well as the impact of the harmonic series truncation. Near- and far-field analytical patterns for the diffusion propagator are examined. The near-field pattern makes available the direct computation of the probability of return to the origin. The far-field pattern allows probing the limitations of the mono-exponential model, which suggests the existence of a limit of validity for DOT. In the regimen from moderate to large displacement lengths the isosurfaces of the diffusion propagator reveal aberrations in form of artifactual peaks. Finally, the major contribution of this work is the derivation of analytical equations that facilitate the accurate reconstruction of some orientational distribution functions (ODFs) and skewness ODFs that are relatively immune to these artifacts. The new formalism was tested using synthetic and real data from a phantom of intersecting capillaries. The results support the hypothesis that the revisited DOT methodology could enhance the estimation of the microgeometry of fiber tissues. PMID:19815083

Canales-Rodríguez, Erick Jorge; Lin, Ching-Po; Iturria-Medina, Yasser; Yeh, Chun-Hung; Cho, Kuan-Hung; Melie-García, Lester

2010-01-15

84

LTL generalized model checking revisited  

Microsoft Academic Search

Given a 3-valued abstraction of a program (possibly generated using static program analysis and predicate abstraction) and\\u000a a temporal logic formula, generalized model checking (GMC) checks whether there exists a concretization of that abstraction\\u000a that satisfies the formula. In this paper, we revisit generalized model checking for linear time (LTL) properties. First,\\u000a we show that LTL GMC is 2EXPTIME-complete in

Patrice Godefroid; Nir Piterman

2008-01-01

85

Benjamin Franklin and Mesmerism, revisited.  

PubMed

The authors revisit and update their previous historiographical note (McConkey & Perry, 1985) on Benjamin Franklin's involvement with and investigation of animal magnetism or mesmerism. They incorporate more recent literature and offer additional comment about Franklin's role in and views about mesmerism. Franklin had a higher degree of personal involvement with and a more detailed opinion of mesmerism than has been previously appreciated. PMID:12362950

McConkey, Kevin M; Perry, Campbell

2002-10-01

86

Language-general and -specific white matter microstructural bases for reading.  

PubMed

In the past decade, several studies have investigated language-general and -specific brain regions for reading. However, very limited research has examined the white matter that connects these cortical regions. By using diffusion tensor imaging (DTI), the current study investigated the common and divergent relationship between white matter integrity indexed by fractional anisotropy (FA) and native language reading abilities in 89 Chinese and 93 English speakers. Conjunction analysis revealed that for both groups, reading ability was associated with the FA of seven white matter fiber bundles in two main anatomical locations in the left hemisphere: the dorsal corona radiate/corpus callosum/superior longitudinal fasciculus which might be for phonological access, and the ventral uncinate fasciculus/external capsule/inferior fronto-occipital fasciculus which might be for semantic processing. Contrast analysis showed that the FA of the left temporal part of superior longitudinal fasciculus contributed more to reading in English than in Chinese, which is consistent with the notion that this tract is involved in grapheme-to-phoneme conversion for alphabetic language reading. These results are the first evidence of language-general and -specific white matter microstructural bases for reading. PMID:24814214

Zhang, Mingxia; Chen, Chuansheng; Xue, Gui; Lu, Zhong-Lin; Mei, Leilei; Xue, Hongli; Wei, Miao; He, Qinghua; Li, Jin; Dong, Qi

2014-09-01

87

Case series: fractional anisotropy along the trajectory of selected white matter tracts in adolescents born preterm with ventricular dilation.  

PubMed

This case series assesses white matter microstructure in 3 adolescents born preterm with nonshunted ventricular dilation secondary to intraventricular hemorrhage. Subjects (ages 12-17 years, gestational age 26-29 weeks, birth weight 825-1624 g) were compared to 3 full-term controls (13-17 years, 39-40 weeks, 3147-3345 g) and 3 adolescents born preterm without ventricular dilation (10-13 years, 26-29 weeks, 630-1673 g). Tractography using a 2 region of interest method reconstructed the following white matter tracts: superior longitudinal/arcuate fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, and corticospinal tract. Subjects showed increased fractional anisotropy and changes in the pattern of fractional anisotropy along the trajectory of tracts adjacent to the lateral ventricles. Tensor shape at areas of increased fractional anisotropy demonstrated increased linear anisotropy at the expense of planar and spherical anisotropy. These findings suggest increased axonal packing density and straightening of fibers secondary to ventricular enlargement. PMID:22859695

Myall, Nathaniel J; Yeom, Kristen W; Yeatman, Jason D; Gaman-Bean, Shayna; Feldman, Heidi M

2013-06-01

88

Interpersonal competence in young adulthood and right laterality in white matter.  

PubMed

The right hemisphere of the human brain is known to be involved in processes underlying emotion and social cognition. Clinical neuropsychology investigations and brain lesion studies have linked a number of personality and social disorders to abnormal white matter (WM) integrity in the right hemisphere. Here, we tested the hypothesis that interpersonal competencies are associated with integrity of WM tracts in the right hemisphere of healthy young adults. Thirty-one participants underwent diffusion tensor imaging scanning. Fractional anisotropy was used to quantify water diffusion. After the scanning session, participants completed the Adolescent Interpersonal Competence Questionnaire. Fractional anisotropy was subsequently correlated with Adolescent Interpersonal Competence Questionnaire scores using tract-based spatial statistics. Higher interpersonal competencies are related to higher WM integrity in several major tracts of the right hemisphere, in specific the uncinate fasciculus, the cingulum, the forceps minor, the infero-fronto occipital fasciculus, the inferior longitudinal fasciculus, and the superior longitudinal fasciculus. These results provide the first direct analysis of the neuroanatomical basis of interpersonal competencies and young adult self-reported skills in social contexts. PMID:24345175

De Pisapia, Nicola; Serra, Mauro; Rigo, Paola; Jager, Justin; Papinutto, Nico; Esposito, Gianluca; Venuti, Paola; Bornstein, Marc H

2014-06-01

89

Radiolytic Cryovolcanism Revisited  

NASA Astrophysics Data System (ADS)

Active geysers of water vapor and ice grains from the south pole of Enceladus are not yet definitively explained in terms of energy sources and processes. Other instances of hot (Io) and cold (Mars, Triton) volcanism beyond Earth are known if not fully understood. We revisit, in comparison to other models, the 'Old Faithful' theory of radiolytic gas-driven cryovolcanism first proposed by Cooper et al. [Plan. Sp. Sci. 2009]. In the energetic electron irradiation environment of Enceladus within Saturn's magnetosphere, a 10-percent duty cycle could be maintained for current geyser activity driven by gases from oxidation of ammonia to N2 and methane to CO2 in the thermal margins of a south polar sea. Much shorter duty cycles down to 0.01 percent would be required to account for thermal power output up to 16 GW, Steady accumulation of oxidant energy over four billion years could have powered all Enceladus emissions over the past four hundred thousand to four hundred million years. There could be separate energy sources driving mass flow and thermal emission over vastly different time scales. Since episodic tidal dissipation on 10 Myr time scales at 0.1 - 1 Gyr intervals [O'Neill and Nimmo, Nature 2010], and thus duty cycles 1 - 10 percent, could heat the polar sea to the current level, the radiolytic energy source could easily power and modulate the geyser mass flow on million-year time scales. Maximum thermal emission temperature 223 K [Abramov and Spencer, Icarus 2009] hints at thermal buffering in the basal and vent wall layers by a 1:1 H2O:H2O2 radiolytic eutectic, assuming deep ice crust saturation with H2O2 from long cumulative surface irradiation and downward ice convection. Due to density stratification the peroxide eutectic and salt water layers could separate, so that the denser peroxide layer (1.2 g/cc) descends to the polar sea while the lighter salt water (1.05 g/cc) rises along separate channels. Methane reservoirs could be found dissolved into the polar sea, or else trapped in hydrates [Kieffer et al., Science 2006] along flow paths and at the walls of the polar sea at surface depths below 20 km [Fortes, Icarus 2007]. Driver gas production for cryovolcanism could occur wherever these two layers come into contact under requisite temperature and pressure conditions, e.g. from 220 K and 10 bar at the 10-km basal layer of the overlying ice crust to 647 K and 220 bars at the liquid water limit, above the core-mantle boundary at 460 bars [Fortes, Icarus 2007]. We expect H2O2 oxidation to ignite at high temperatures but metallic minerals could catalyze reactions at lower temperatures nearer the basal layer. Pressure effects on oxidation rates are uncertain. Definitive modeling of Enceladus cryovolcanism likely involves synthesis of key processes from multiple models: Cold Faithful [Porco et al., Science 2006], Frigid Faithful [Keiffer et al., Science 2006], Frothy Faithful [Fortes, Icarus 2007], Old Faithful, and 'Perrier Ocean' recirculation [Matson et al., Icarus 2012].

Cooper, J. F.; Cooper, P. D.; Sittler, E. C.; Wesenberg, R. P.

2013-12-01

90

Lithium and GSK3-? Promoter Gene Variants Influence White Matter Microstructure in Bipolar Disorder  

PubMed Central

Lithium is the mainstay for the treatment of bipolar disorder (BD) and inhibits glycogen synthase kinase 3-? (GSK3-?). The less active GSK3-? promoter gene variants have been associated with less detrimental clinical features of BD. GSK3-? gene variants and lithium can influence brain gray matter structure in psychiatric conditions. Diffusion tensor imaging (DTI) measures of white matter (WM) integrity showed widespred disruption of WM structure in BD. In a sample of 70 patients affected by a major depressive episode in course of BD, we investigated the effect of ongoing long-term lithium treatment and GSK3-? promoter rs334558 polymorphism on WM microstructure, using DTI and tract-based spatial statistics with threshold-free cluster enhancement. We report that the less active GSK3-? rs334558*C gene-promoter variants, and the long-term administration of the GSK3-? inhibitor lithium, were associated with increases of DTI measures of axial diffusivity (AD) in several WM fiber tracts, including corpus callosum, forceps major, anterior and posterior cingulum bundle (bilaterally including its hippocampal part), left superior and inferior longitudinal fasciculus, left inferior fronto-occipital fasciculus, left posterior thalamic radiation, bilateral superior and posterior corona radiata, and bilateral corticospinal tract. AD reflects the integrity of axons and myelin sheaths. We suggest that GSK3-? inhibition and lithium could counteract the detrimental influences of BD on WM structure, with specific benefits resulting from effects on specific WM tracts contributing to the functional integrity of the brain and involving interhemispheric, limbic, and large frontal, parietal, and fronto-occipital connections.

Benedetti, Francesco; Bollettini, Irene; Barberi, Ignazio; Radaelli, Daniele; Poletti, Sara; Locatelli, Clara; Pirovano, Adele; Lorenzi, Cristina; Falini, Andrea; Colombo, Cristina; Smeraldi, Enrico

2013-01-01

91

Lithium in the Pleiades Revisited  

NASA Astrophysics Data System (ADS)

New Li abundances have been derived for some 15-20 Pleiades dwarfs using new high-resolution and high S/N spectroscopy from HET/HRS. Previous studies suggested that our objects, all modest (projected) rotators, evinced considerable scatter in their Li abundances. We revisit the question of this scatter and its origin. This work has been supported by NSF grants AST 00-86576 and 02-39518, a South Carolina Space Grant Scholarship award, a generous donation from the Curry Foundation of Seneca, SC, and the NOAO Public Access Program.

King, J. R.; Hobbs, L. M.; Schuler, S. C.; Pinsonneault, M. H.

2003-12-01

92

SLIM--An Early Work Revisited  

SciTech Connect

An early, but at the time illuminating, piece of work on how to deal with a general, linearly coupled accelerator lattice is revisited. This work is based on the SLIM formalism developed in 1979-1981.

Chao, Alex; /SLAC

2008-07-25

93

Revisiting Cometary Bow Shock Positions  

NASA Astrophysics Data System (ADS)

The Rosetta spacecraft will arrive at comet 67P/Churyumov-Gerasimenko in 2014 and will escort the comet along its journey around the Sun. The predicted outgassing rate of the comet and the solar wind properties next to its perihelion at 1.24 AU lead to the expectation that a cometary bow shock will form during the escort phase. Since the forecasts of the subsolar stand off distances differ, this study revisits selected models and presents hybrid simulations of the comet-solar wind interaction region performed with the A.I.K.E.F. code. In addition, an analytical model is presented that reproduces the bow shock distances observed in the hybrid simulations.

Koenders, C.; Glassmeier, K.-H.; Richter, I.; Motschmann, U.; Rubin, M.

2013-09-01

94

Revisiting cometary bow shock positions  

NASA Astrophysics Data System (ADS)

The Rosetta spacecraft will arrive at comet 67P/Churyumov-Gerasimenko in 2014 and will escort the comet along its journey around the Sun. The predicted outgassing rate of the comet and the solar wind properties close to its perihelion at 1.24 AU lead to the expectation that a cometary bow shock will form during the escort phase. Since the forecasts of the subsolar stand off distances differ, this study revisits selected models and presents hybrid simulations of the comet-solar wind interaction region performed with the A.I.K.E.F. code. It is shown that small variations of the solar wind parameters will shift the bow shock position considerably. In addition, a model is presented that reproduces the bow shock distances observed in the hybrid simulations.

Koenders, C.; Glassmeier, K.-H.; Richter, I.; Motschmann, U.; Rubin, M.

2013-10-01

95

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

PubMed Central

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 CR 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.

Bendlin, B.B.; Canu, E.; Willette, A.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.

2010-01-01

96

Alterations in frontal lobe tracts and corpus callosum in young children with autism spectrum disorder.  

PubMed

Major frontal lobe tracts and corpus callosum (CC) were investigated in 32 children with autism spectrum disorder (ASD, mean age: 5 years), 12 nonautistic developmentally impaired children (DI, mean age: 4.6 years), and 16 typically developing children (TD, mean age: 5.5 years) using diffusion tensor imaging tractography and tract-based spatial statistics. Various diffusion and geometric properties were calculated for uncinate fasciculus (UF), inferior fronto-occipital fasciculus (IFO), arcuate fasciculus (AF), cingulum (Cg), CC, and corticospinal tract. Fractional anisotropy was lower in the right UF, right Cg and CC in ASD and DI children; in right AF in ASD children; and in bilateral IFO in DI children, compared with TD children. Apparent diffusion coefficient was increased in right AF in both ASD and DI children. The ASD group showed shorter length of left UF and increased length, volume, and density of right UF; increased length and density of CC; and higher density of left Cg, compared with the TD group. Compared with DI group, ASD group had increased length, volume, and density of right UF; higher volume of left UF; and increased length of right AF and CC. Volume of bilateral UF and right AF and fiber density of left UF were positively associated with autistic features. PMID:20019145

Kumar, Ajay; Sundaram, Senthil K; Sivaswamy, Lalitha; Behen, Michael E; Makki, Malek I; Ager, Joel; Janisse, James; Chugani, Harry T; Chugani, Diane C

2010-09-01

97

White matter integrity is associated with cerebrospinal fluid markers of Alzheimer's disease in normal adults.  

PubMed

We explored whether white matter (WM) integrity in cognitively normal (CN) older adults is associated with cerebrospinal fluid (CSF) markers of Alzheimer's disease pathology. Twenty CN older adults underwent lumbar puncture and magnetic resonance imaging within a few days of each other. Analysis of diffusion tensor imaging data involved a priori region of interest and voxelwise approaches. The region of interest results revealed a positive correlation between CSF measures of amyloid-beta (A?42 and A?42/p-Tau181) and WM integrity in the fornix, a relationship which persisted after controlling for hippocampal volume and fornix volume. Lower WM integrity in the same portion of the fornix was also associated with reduced performance on the Digit Symbol test. Subsequent exploratory voxelwise analyses indicated a positive correlation between CSF A?42/p-Tau181 and WM integrity in bilateral portions of the fornix, superior longitudinal fasciculus, inferior fronto-occipital fasciculus, and in the corpus callosum and left inferior longitudinal fasciculus. Our results link lower WM microstructural integrity in CN older adults with CSF biomarkers of Alzheimer's disease and suggest that this association in the fornix may be independent of volumetric measures. PMID:24866404

Gold, Brian T; Zhu, Zude; Brown, Christopher A; Andersen, Anders H; LaDu, Mary Jo; Tai, Leon; Jicha, Greg A; Kryscio, Richard J; Estus, Steven; Nelson, Peter T; Scheff, Steve W; Abner, Erin; Schmitt, Frederick A; Van Eldik, Linda J; Smith, Charles D

2014-10-01

98

Clinical correlations of microstructural changes in progressive supranuclear palsy.  

PubMed

In patients with progressive supranuclear palsy (PSP), previous reports have shown a severe white matter (WM) damage involving supra and infratentorial regions including cerebellum. In the present study, we investigated potential correlations between WM integrity loss and clinical-cognitive features of patients with PSP. By using magnetic resonance imaging and diffusion tensor imaging with tract based spatial statistic analysis, we analyzed WM volume in 18 patients with PSP and 18 healthy controls (HCs). All patients and HCs underwent a detailed clinical and neuropsychological evaluation. Relative to HCs, patients with PSP showed WM changes encompassing supra and infratentorial areas such as corpus callosum, fornix, midbrain, inferior fronto-occipital fasciculus, anterior thalamic radiation, superior cerebellar peduncle, superior longitudinal fasciculus, uncinate fasciculus, cingulate gyrus, and cortico-spinal tract bilaterally. Among different correlations between motor-cognitive features and WM structural abnormalities, we detected a significant association between fronto-cerebellar WM loss and executive cognitive impairment in patients with PSP. Our findings, therefore, corroborate the hypothesis that cognitive impairment in PSP may result from both "intrinsic" and "extrinsic" frontal lobe dysfunction, likely related to cerebellar disconnection. PMID:24786632

Tessitore, Alessandro; Giordano, Alfonso; Caiazzo, Giuseppina; Corbo, Daniele; De Micco, Rosa; Russo, Antonio; Liguori, Sara; Cirillo, Mario; Esposito, Fabrizio; Tedeschi, Gioacchino

2014-10-01

99

PATHOLOGY OF HUMAN INFLUENZA REVISITED  

PubMed Central

Summary The pathology of human influenza has been studied most intensively during the three pandemics of the last century, the last of which occurred in 1968. It is important to revisit this subject because of the recent emergence of avian H5N1 influenza in humans as well as the threat of a new pandemic. Uncomplicated human influenza virus infection causes transient tracheo-bronchitis, corresponding with predominant virus attachment to tracheal and bronchial epithelial cells. The main complication is extension of viral infection to the alveoli, often with secondary bacterial infection, resulting in severe pneumonia. Complications in extra-respiratory tissues such as encephalopathy, myocarditis, and myopathy occur occasionally. Sensitive molecular and immunological techniques allow us to investigate whether these complications are a direct result of virus infection or an indirect result of severe pneumonia. Human disease from avian influenza virus infections is most severe for subtype H5N1, but also has been reported for H7 and H9 subtypes. In contrast to human influenza viruses, avian H5N1 virus attaches predominantly to alveolar and bronchiolar epithelium, corresponding with diffuse alveolar damage as the primary lesion. Viremia and extra-respiratory complications appear to be more common for infections with avian H5N1 virus than with human influenza viruses. Further understanding and comparison of the pathology of human and avian influenza virus infections only can be achieved by directed and careful pathological analysis of additional influenza cases.

Kuiken, Thijs; Taubenberger, Jeffery

2008-01-01

100

Revisiting Bohr's semiclassical quantum theory.  

PubMed

Bohr's atomic theory is widely viewed as remarkable, both for its accuracy in predicting the observed optical transitions of one-electron atoms and for its failure to fully correspond with current electronic structure theory. What is not generally appreciated is that Bohr's original semiclassical conception differed significantly from the Bohr-Sommerfeld theory and offers an alternative semiclassical approximation scheme with remarkable attributes. More specifically, Bohr's original method did not impose action quantization constraints but rather obtained these as predictions by simply matching photon and classical orbital frequencies. In other words, the hydrogen atom was treated entirely classically and orbital quantized emerged directly from the Planck-Einstein photon quantization condition, E = h nu. Here, we revisit this early history of quantum theory and demonstrate the application of Bohr's original strategy to the three quintessential quantum systems: an electron in a box, an electron in a ring, and a dipolar harmonic oscillator. The usual energy-level spectra, and optical selection rules, emerge by solving an algebraic (quadratic) equation, rather than a Bohr-Sommerfeld integral (or Schroedinger) equation. However, the new predictions include a frozen (zero-kinetic-energy) state which in some (but not all) cases lies below the usual zero-point energy. In addition to raising provocative questions concerning the origin of quantum-chemical phenomena, the results may prove to be of pedagogical value in introducing students to quantum mechanics. PMID:17020371

Ben-Amotz, Dor

2006-10-12

101

Principal eigenvector field segmentation for reproducible diffusion tensor tractography of white matter structures.  

PubMed

The study was aimed to test the feasibility of utilizing an algorithmically determinable stable fiber mass (SFM) map obtained by an unsupervised principal eigenvector field segmentation (PEVFS) for automatic delineation of 18 white matter (WM) tracts: (1) corpus callosum (CC), (2) tapetum (TP), (3) inferior longitudinal fasciculus (ILF), (4) uncinate fasciculus (UNC), (5) inferior fronto-occipital fasciculus (IFO), (6) optic pathways (OP), (7) superior longitudinal fasciculus (SLF), (8) arcuate fasciculus (AF), (9) fornix (FX), (10) cingulum (CG), (11) anterior thalamic radiation (ATR), (12) superior thalamic radiation (STR), (13) posterior thalamic radiation (PTR), (14) corticospinal/corticopontine tract (CST/CPT), (15) medial lemniscus (ML), (16) superior cerebellar peduncle (SCP), (17) middle cerebellar peduncle (MCP) and (18) inferior cerebellar peduncle (ICP). Diffusion tensor imaging (DTI)-derived fractional anisotropy (FA) and the principal eigenvector field have been used to create the SFM consisting of a collection of linear voxel structures which are grouped together by color-coding them into seven natural classes to provide PEVFS signature segments which greatly facilitate the selection of regions of interest (ROIs) for fiber tractography using just a single mouse click, as compared with a manual drawing of ROIs in the classical approach. All the 18 fiber bundles have been successfully reconstructed, in all the subjects, using the single ROIs provided by the SFM approach, with their reproducibility characterized by the fact that the ROI selection is user independent. The essentially automatic PEVFS method is robust, efficient and compares favorably with the classical ROI methods for diffusion tensor tractography (DTT). PMID:21664783

Rathore, Ram K S; Gupta, Rakesh K; Agarwal, Shruti; Trivedi, Richa; Tripathi, Rajendra P; Awasthi, Rishi

2011-10-01

102

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

103

Revisitation patterns in World Wide Web navigation  

Microsoft Academic Search

We report on users' revisitation patterns to World Wide Web pages, and use these to lay an empirical foundation for the design of history mechanisms in web browsers. Through history, a user can return quickly to a previously visited page, possibly reducing the cognitive and physical overhead required to navigate to it from scratch. We analyzed 6 weeks of usage

Linda Tauscher; Saul Greenberg

1997-01-01

104

Aid, Policies, and Growth: Revisiting the Evidence  

Microsoft Academic Search

Burnside and Dollar revisit the relationship between aid and growth using a new data set focusing on the 1990s. The evidence supports the view that the impact of aid depends on the quality of state institutions and policies. The authors use an overall measure of institutions and policies popular in the empirical growth literature. The interaction of aid and institutional

Craig Burnside; David Dollar

2004-01-01

105

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

106

Security of Invertible Media Authentication Schemes Revisited  

Microsoft Academic Search

Dittmann, Katzenbeisser, Schallhart and Veith (IACR ePrint 2004) intro- duced the notion of invertible media authentication schemes, embedding authentication data in media objects via invertible watermarks. These invertible watermarks allow to recover the original media object (given a secret encryption key), as required for example in some medical applications where the distortion must be removable. Here we revisit the approach

Daniel Dönigus; Stefan Endler; Marc Fischlin; Andreas Hülsing; Patrick Jäger; Anja Lehmann; Sergey Podrazhansky; Sebastian Schipp; Erik Tews; Sven Vowe; Matthias Walthart; Frederik Weidemann

2007-01-01

107

Pair Production Constraints on Superluminal Neutrinos Revisited.  

National Technical Information Service (NTIS)

We revisit the pair creation constraint on superluminal neutrinos considered by Cohen and Glashow in order to clarify which types of superluminal models are constrained. We show that a model in which the superluminal neutrino is effectively light-like can...

S. Gardner S. J. Brodsky

2011-01-01

108

Revisiting the Regenerative Possibilities of Ortiz  

ERIC Educational Resources Information Center

The author of this article revisits Simon Ortiz's poem, "From Sand Creek," in which the latter can in so few words convey both the horrific tragedy of conquest and colonization, while at the same time find a space for possibility, a means for recovery that is never about forgetting but always occurs as a kind of recuperative remembering. Ortiz…

Duques, Matthew

2004-01-01

109

The Evil of Banality: Arendt Revisited  

ERIC Educational Resources Information Center

"The banality of evil" (Arendt) remains controversial and useful. Ironically, the concept is now itself a banality. To revisit and extend it, we consider the "evil of banality", the profound dangers of cliched thoughtlessness. A distinction is proposed: "intensive" versus "extensive evils". The former takes…

Minnich, Elizabeth

2014-01-01

110

Dispelling the Myth Revisited: Additional Tables.  

ERIC Educational Resources Information Center

In December 2001, the Education Trust released preliminary findings from its new database, Dispelling the Myth Online, in a report titled Dispelling the Myth Revisited (DTMR). This followup report is the first of several multilayered looks at high-performing schools in the database. It contains additional information about DTMR schools. The lists…

Education Trust, Washington, DC.

111

Closing reflections on 'Revisiting Apartheid's Race Categories'  

Microsoft Academic Search

In these closing reflections, I wish to open up a set of questions by drawing upon a larger historical canvass in order to historicise the question of revisiting apartheid race categories and locate it within a global frame. I will frame these thoughts around a few keywords - modernity, race categories, apartheid and beyond. Perhaps the first truly notable instance

Harry Garuba

2012-01-01

112

"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

113

Revisiting the Definition of Homo Sapiens  

Microsoft Academic Search

Research in genomics, human cloning, and transgenic technology has challenged bioethicists and scientists to rethink the definition of human be- ings as a species. For example, should the definition incorporate a genetic crite- rion and how does the capacity to genetically engineer human beings affect the definition of our species? In considering these contemporary bioethical dilem- mas, we revisit an

John D. Loike; Moshe David Tendler

2002-01-01

114

Revisiting the Political Theory of Party Identification  

Microsoft Academic Search

Recently, Lewis-Beck et al. (The American Voter Revisited, 2008b) re-created The American Voter using contemporary data. Although these scholars ultimately conclude that voters today behave in ways that are consistent\\u000a with the account of voting behavior presented in The American Voter, their work nonetheless highlights the importance and value of re-examining past ideas. Given that Lewis-Beck et al. have\\u000a re-tested the findings

Aaron C. Weinschenk

2010-01-01

115

Setting the revisit interval in primary care  

Microsoft Academic Search

OBJECTIVE: Although longitudinal care constitutes the bulk of primary care, physicians receive little guidance on the fundamental question\\u000a of how to time follow-up visits. We sought to identify important predictors of the revisit interval and to describe the variability\\u000a in how physicians set these intervals when caring for patients with common medical conditions.\\u000a \\u000a \\u000a DESIGN: Cross-sectional survey of physicians performed at

Lisa M. Schwartz; Steven Woloshin; John H. Wasson; Roger A. Renfrew; H. Gilbert Welch

1999-01-01

116

Damage to Association Fiber Tracts Impairs Recognition of the Facial Expression of Emotion  

PubMed Central

An array of cortical and subcortical structures have been implicated in the recognition of emotion from facial expressions. It remains unknown how these regions communicate as parts of a system to achieve recognition, but white matter tracts are likely critical to this process. We hypothesized that (1) damage to white matter tracts would be associated with recognition impairment and (2) the degree of disconnection of association fiber tracts [inferior longitudinal fasciculus (ILF) and/or inferior fronto-occipital fasciculus (IFOF)] connecting the visual cortex with emotion-related regions would negatively correlate with recognition performance. One hundred three patients with focal, stable brain lesions mapped onto a reference brain were tested on their recognition of six basic emotional facial expressions. Association fiber tracts from a probabilistic atlas were coregistered to the reference brain. Parameters estimating disconnection were entered in a general linear model to predict emotion recognition impairments, accounting for lesion size and cortical damage. Damage associated with the right IFOF significantly predicted an overall facial emotion recognition impairment and specific impairments for sadness, anger, and fear. One subject had a pure white matter lesion in the location of the right IFOF and ILF. He presented specific, unequivocal emotion recognition impairments. Additional analysis suggested that impairment in fear recognition can result from damage to the IFOF and not the amygdala. Our findings demonstrate the key role of white matter association tracts in the recognition of the facial expression of emotion and identify specific tracts that may be most critical.

Philippi, Carissa L.; Mehta, Sonya; Grabowski, Thomas; Adolphs, Ralph; Rudrauf, David

2010-01-01

117

Individual differences in white matter anatomy predict dissociable components of reading skill in adults.  

PubMed

We used diffusion tensor imaging (DTI) to investigate relationships between white matter anatomy and different reading subskills in typical-reading adults. A series of analytic approaches revealed that phonological decoding ability is associated with anatomical markers that do not relate to other reading-related cognitive abilities. Thus, individual differences in phonological decoding might relate to connectivity between a network of cortical regions, while skills like sight word reading might rely less strongly on integration across regions. Specifically, manually-drawn ROIs and probabilistic tractography revealed an association between the volume and integrity of white matter underlying primary auditory cortex and nonword reading ability. In a related finding, more extensive cross-hemispheric connections through the isthmus of the corpus callosum predicted better phonological decoding. Atlas-based white matter ROIs demonstrated that relationships with nonword reading were strongest in the inferior fronto-occipital fasciculus and uncinate fasciculus that connect occipital and anterior temporal cortex with inferior frontal cortex. In contrast, tract volume underlying the left angular gyrus was related to nonverbal IQ. Finally, connectivity underlying functional ROIs that are differentially active during phonological and semantic processing predicted nonword reading and reading comprehension, respectively. Together, these results provide important insights into how white matter anatomy may relate to both typical reading subskills, and perhaps a roadmap for understanding neural connectivity in individuals with reading impairments. PMID:24704456

Welcome, Suzanne E; Joanisse, Marc F

2014-08-01

118

Diffusion Tensor Imaging of Aicardi Syndrome  

PubMed Central

Aicardi syndrome is a congenital neurodevelopmental disorder associated with significant cognitive and motor impairment. Diffusion Tensor Imaging was performed on two subjects with Aicardi syndrome, as well as on two matched subjects with callosal agenesis and cortical malformations, but not a clinical diagnosis of Aicardi syndrome. Whole brain three-dimensional fiber tractography was performed, and major white matter tracts were isolated using standard tracking protocols. One Aicardi subject demonstrated an almost complete lack of normal cortico-cortical connectivity, with only the left inferior fronto-occipital fasciculus recovered by diffusion tensor tractography. A second Aicardi subject showed evidence of bilateral cingulum bundles and right uncinate fasciculus, but other cortico-cortical tracts were not recovered. Major subcortical white matter tracts, including corticospinal, pontocerebellar, and anterior thalamic radiation tracts, were recovered in both Aicardi subjects. In contrast, diffusion tensor tractography analysis on the two matched control subjects with callosal agenesis and cortical malformations recovered all major intrahemispheric cortical and subcortical white matter tracts. These results reveal a widespread disruption in the corticocortical white matter organization of individuals with Aicardi syndrome. Furthermore, such disruption in white matter organization appears to be a feature specific to Aicardi syndrome, and not shared by other neurodevelopmental disorders with similar anatomic manifestations.

Wahl, Michael; Strominger, Zoe A.; Wakahiro, Mari; Jeremy, Rita J.; Mukherjee, Pratik; Sherr, Elliott H.

2010-01-01

119

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

2013-02-28

120

White Matter Integrity, Substance Use, and Risk Taking in Adolescence  

PubMed Central

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 non-users (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: 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.

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

2012-01-01

121

Multivariate pattern analysis of DTI reveals differential white matter in individuals with obsessive-compulsive disorder.  

PubMed

Diffusion tensor imaging (DTI) studies have revealed group differences in white matter between patients with obsessive-compulsive disorder (OCD) and healthy controls. However, the results of these studies were based on average differences between the two groups, and therefore had limited clinical applicability. The objective of this study was to investigate whether fractional anisotropy (FA) of white matter can be used to discriminate between patients with OCD and healthy controls at the level of the individual. DTI data were acquired from 28 OCD patients and 28 demographically matched healthy controls, scanned using a 3T MRI system. Differences in FA values of white matter between OCD and healthy controls were examined using a multivariate pattern classification technique known as support vector machine (SVM). SVM applied to FA images correctly identified OCD patients with a sensitivity of 86% and a specificity of 82% resulting in a statistically significant accuracy of 84% (P ? 0.001). This discrimination was based on a distributed network including bilateral prefrontal and temporal regions, inferior fronto-occipital fasciculus, superior fronto-parietal fasciculus, splenium of corpus callosum and left middle cingulum bundle. The present study demonstrates subtle and spatially distributed white matter abnormalities in individuals with OCD, and provides preliminary support for the suggestion that that these could be used to aid the identification of individuals with OCD in clinical practice. PMID:24048702

Li, Fei; Huang, Xiaoqi; Tang, Wanjie; Yang, Yanchun; Li, Bin; Kemp, Graham J; Mechelli, Andrea; Gong, Qiyong

2014-06-01

122

Alterations in white matter pathways in Angelman syndrome  

PubMed Central

Aim Angelman syndrome is a neurogenetic disorder characterized by severe intellectual disability, absent speech, seizures, and outbursts of laughter. The aim of this study was to utilize diffusion tensor imaging (DTI) to examine alterations in white matter pathways in Angelman syndrome, with an emphasis on correlations with clinical severity. Methods DTI was used to examine the arcuate fasciculus (AF), uncinate fasciculus (UF), inferior longitudinal fasciculus (ILF), inferior fronto-occipital fasciculus (IFOF), and the corpus callosum (CC). We enrolled 14 children aged 8 to 17 years (mean age 10y 8mo; SD 2y 7mo) with Angelman syndrome (seven male; seven female) and 13 typically developing children, aged 8 to 17 years, for comparison (five male; eight female; mean age 12y; SD 2y 9mo). Individuals with Angelman syndrome were assessed using standardized measures of development, language, and behaviour. Results The children with Angelman syndrome exhibited lower fractional anisotropy and increased radial diffusivity values than the comparison group for the AF, UF, ILF, and CC (p<0.006 corrected for multiple comparisons). They also had lower fractional anisotropy values for the IFOF and higher radial diffusivity values for the left IFOF (p<0.006). Additionally, children with Angelman syndrome had significantly higher apparent diffusion coefficient values in the AF, CC, ILF, and the left IFOF (p<0.006). Significant correlations were noted between DTI parameters and some of the clinical assessment outcomes (e.g. language, socialization, cognition) for three of the temporal pathways (AF, UF, ILF; p<0.05). Interpretation Changes in DTI parameters in individuals with Angelman syndrome suggest decreased/delayed myelination, decreased axonal density or diameter, or aberrant axonal organization. Our findings suggest a generalized white matter alteration throughout the brain in those with Angelman syndrome; however, only the alterations in temporal white matter pathways were associated with language and cognitive and social functioning.

PETERS, SARIKA U; KAUFMANN, WALTER E; BACINO, CARLOS A; ANDERSON, ADAM W; ADAPA, PAVANI; CHU, ZILI; YALLAMPALLI, RAGINI; TRAIPE, ELFRIDES; HUNTER, JILL V; WILDE, ELISABETH A

2010-01-01

123

The mid-domain effect revisited.  

PubMed

We revisit the proposition that boundary constraints on species' ranges cause species richness gradients (the mid-domain effect [MDE] hypothesis). In the absence of environmental gradients, species should not retain their observed range sizes as assumed by MDE models. Debate remains regarding the definition of domain limits, valid predictions for testing the models, and their statistical assessment. Empirical support for the MDE is varied but often weak, suggesting that geometric constraints on species' ranges do not provide a general explanation for richness gradients. Criticism of MDE model assumptions does not, however, imply opposition to the use of null models in ecology. PMID:16224717

Zapata, Fernando A; Gaston, Kevin J; Chown, Steven L

2005-11-01

124

Revisiting eukaryotic anti-infective biotherapeutics.  

PubMed

Emerging drug resistance has forced the scientific community to revisit the observational data documented in the folklore and come up with novel and effective alternatives. Candidates from eukaryotic origin including herbal products and antimicrobial peptides are finding a strategic place in the therapeutic armamentarium against infectious diseases. These agents have recently gained interest owing to their versatile applications. Present review encompasses the use of these alternative strategies in their native or designer form, alone or in conjunction with antibiotics, as possible remedial measures. Further to this, the limitations or the possible concerns associated with these options are also discussed at length. PMID:23317462

Rishi, Praveen; Singh, Aman Preet; Arora, Sumeha; Garg, Neha; Kaur, Indu Pal

2014-11-01

125

Revisiting Resistance Speeds Up I\\/O-Efficient LTL Model Checking  

Microsoft Academic Search

Revisiting resistant graph algorithms are those that can tolerate re- exploration of edges without yielding incorrect results. Revisiting resistant I\\/O efficient graph algorithms exhibit considerable speed-up in practice in compari- son to non-revisiting resistant algorithms. In the paper we present a new revisiting resistant I\\/O efficient LTL model checking algorithm. We analyze its theoretical I\\/O complexity and we experimentally compare

Jiri Barnat; Lubos Brim; Pavel Simecek; M. Weber; C. R. Ramakrishnan; J Rehof

2008-01-01

126

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

127

The need to revisit lipid areas  

NASA Astrophysics Data System (ADS)

We have studied the structural properties of lipid bilayers made up of monounsaturated phosphatidylcholines (i.e. diCn:1PC, where n=14, 16, 18, 20, 22 and 24). High-resolution x-ray scattering data were analyzed in conjunction with contrast varied neutron scattering data, using the recently developed technique by Ku?erka et al. [Biophys. J. 95, 2356 (2008)]. Analyses of the data show that with increasing n lipid bilayers do not thicken in a linear fashion, as is often assumed, but quadratically, and that lipid area assumes a maximum value for n~18 bilayers. More importantly, compared to previous data our results strongly suggest that lipid areas are smaller by about 10%. This observation highlights the need to revisit lipid areas as they are extensively used in molecular dynamics simulations and for calibrating their force fields.

Ku?erka, N.; Gallová, J.; Uhríková, D.; Balgavý, P.; Katsaras, J.

2010-11-01

128

Electron heating in capacitively coupled plasmas revisited  

NASA Astrophysics Data System (ADS)

We revisit the problem of electron heating in capacitively coupled plasmas (CCPs), and propose a method for quantifying the level of collisionless and collisional heating in plasma simulations. The proposed procedure, based on the electron mechanical energy conservation equation, is demonstrated with particle-in-cell simulations of a number of single and multi-frequency CCPs operated in regimes of research and industrial interest. In almost all cases tested, the total electron heating is comprised of collisional (ohmic) and pressure heating parts. This latter collisionless component is in qualitative agreement with the mechanism of electron heating predicted from the recent re-evaluation of theoretical models. Finally, in very electrically asymmetric plasmas produced in multi-frequency discharges, we observe an additional collisionless heating mechanism associated with electron inertia.

Lafleur, T.; Chabert, P.; Booth, J. P.

2014-06-01

129

Revisiting the stability of pulsatile pipe flow  

NASA Astrophysics Data System (ADS)

It is well known that pulsatile pipe flow is stable for small axisymmetric perturbations. Here, we revisit the stability of the flow proposing to solve for the stream function of axisymmetric perturbations by projecting the fourth order Orr-Sommerfeld equation onto an approximation function space. The derived time-periodic system of first order differential equations has solution which admits an expansion in terms of non-orthogonal eigenmodes, representing in physical space, characteristic flow structures of toroidal vortex tubes. A multi-scale perturbation analysis in the longwave limit predicts that the disturbance is not influenced by the pulsatility of the basic flow for large Strouhal number, since the oscillatory time scale is much faster than the disturbance time scale. Our numerical results are in agreement with the perturbation analysis and confirm the known stability of the flow. Finally, it is found that the optimal initial disturbance giving the largest energy growth consists of vortex tubes localized closer to the wall.

Fedele, Francesco; Hitt, Darren; Prabhu, Rachakonda

2003-11-01

130

Pathogenesis of progressive multifocal leukoencephalopathy--revisited.  

PubMed

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. PMID:21227915

White, Martyn K; Khalili, Kamel

2011-03-01

131

Left hemisphere fractional anisotropy increase in noise-induced tinnitus: a diffusion tensor imaging (DTI) study of white matter tracts in the brain.  

PubMed

Diffusion tensor imaging (DTI) is a contemporary neuroimaging modality used to study connectivity patterns and microstructure of white matter tracts in the brain. The use of DTI in the study of tinnitus is a relatively unexplored methodology with no studies focusing specifically on tinnitus induced by noise exposure. In this investigation, participants were two groups of adults matched for etiology, age, and degree of peripheral hearing loss, but differed by the presence or absence (+/-) of tinnitus. It is assumed that matching individuals on the basis of peripheral hearing loss, allows for differentiating changes in white matter microstructure due to hearing loss from changes due to the effects of chronic tinnitus. Alterations in white matter tracts, using the fractional anisotropy (FA) metric, which measures directional diffusion of water, were quantified using tract-based spatial statistics (TBSS) with additional details provided by in vivo probabilistic tractography. Our results indicate that 10 voxel clusters differentiated the two groups, including 9 with higher FA in the group with tinnitus. A decrease in FA was found for a single cluster in the group with tinnitus. However, seven of the 9 clusters with higher FA were in left hemisphere thalamic, frontal, and parietal white matter. These foci were localized to the anterior thalamic radiations and the inferior and superior longitudinal fasciculi. The two right-sided clusters with increased FA were located in the inferior fronto-occipital fasciculus and superior longitudinal fasciculus. The only decrease in FA for the tinnitus-positive group was found in the superior longitudinal fasciculus of the left parietal lobe. PMID:24212050

Benson, Randall R; Gattu, Ramtilak; Cacace, Anthony T

2014-03-01

132

White Matter Hyperintensities, Exercise and Improvement in Gait Speed: Does the Type of Gait Rehabilitation Matter?  

PubMed Central

Background and Objectives White matter hyperintensities (WMH) on brain MRI are associated with cognitive and mobility impairment in older adults. We examined whether WMH in tracts in older adults with mobility impairment are linked to outcomes of gait rehabilitation interventions. Design A 12-week randomized controlled single-blind trial. Setting University-based mobility research laboratory. Participants Ambulatory adults aged 65 and older with mobility impairment. Intervention A conventional gait intervention focusing on walking, endurance, balance, and strength (WEBS, n=21) compared to a task-oriented intervention focused on timing and coordination of gait (TC, n=23). Measurements We measured self-paced gait speed over an instrumented walkway, pre and post intervention, and quantified WMH and brain volumes on pre-intervention brain MRI using an automated segmentation process. We overlaid a white matter tract atlas on the segmented images to measure tract WMH volumes and normalized WMH volumes to total brain volume. Aggregate WMH volumes in all white matter tracts and individual WMH volumes in specific longitudinal tracts (the superior longitudinal fasciculus, inferior longitudinal fasciculus and the fronto-occipital fasciculus) and cingulum were obtained. Results Gait speed gains in the TC group were of the same magnitude, independent of the WMH volume measures in all except the cingulum. However, in the WEBS group, gain in gait speed was smaller with greater overall tract WMH volumes (P<0.001) and with greater WMH volume in the three longitudinal tracts (P< 0.001 to 0.025). Conclusion Gains in gait speed with two types of gait rehabilitation are associated with individual differences in WMH. Task-oriented therapy that targets timing and coordination of gait may particularly benefit older adults with WMH in brain tracts that influence gait and cognition.

Nadkarni, Neelesh K.; Studenski, Stephanie A.; Perera, Subashan; Rosano, Caterina; Aizenstein, Howard J.; Brach, Jennifer S.; VanSwearingen, Jessie M.

2013-01-01

133

Evaluation of Diffusion-Tensor Imaging-Based Global Search and Tractography for Tumor Surgery Close to the Language System  

PubMed Central

Pre-operative planning and intra-operative guidance in neurosurgery require detailed information about the location of functional areas and their anatomo-functional connectivity. In particular, regarding the language system, post-operative deficits such as aphasia can be avoided. By combining functional magnetic resonance imaging and diffusion tensor imaging, the connectivity between functional areas can be reconstructed by tractography techniques that need to cope with limitations such as limited resolution and low anisotropic diffusion close to functional areas. Tumors pose particular challenges because of edema, displacement effects on brain tissue and infiltration of white matter. Under these conditions, standard fiber tracking methods reconstruct pathways of insufficient quality. Therefore, robust global or probabilistic approaches are required. In this study, two commonly used standard fiber tracking algorithms, streamline propagation and tensor deflection, were compared with a previously published global search, Gibbs tracking and a connection-oriented probabilistic tractography approach. All methods were applied to reconstruct neuronal pathways of the language system of patients undergoing brain tumor surgery, and control subjects. Connections between Broca and Wernicke areas via the arcuate fasciculus (AF) and the inferior fronto-occipital fasciculus (IFOF) were validated by a clinical expert to ensure anatomical feasibility, and compared using distance- and diffusion-based similarity metrics to evaluate their agreement on pathway locations. For both patients and controls, a strong agreement between all methods was observed regarding the location of the AF. In case of the IFOF however, standard fiber tracking and Gibbs tracking predominantly identified the inferior longitudinal fasciculus that plays a secondary role in semantic language processing. In contrast, global search resolved connections in almost every case via the IFOF which could be confirmed by probabilistic fiber tracking. The results show that regarding the language system, our global search is superior to clinically applied conventional fiber tracking strategies with results similar to time-consuming global or probabilistic approaches.

Richter, Mirco; Zolal, Amir; Ganslandt, Oliver; Buchfelder, Michael; Nimsky, Christopher; Merhof, Dorit

2013-01-01

134

White Matter Abnormalities in Patients with Focal Cortical Dysplasia Revealed by Diffusion Tensor Imaging Analysis in a Voxelwise Approach  

PubMed Central

Background: Diffusion tensor imaging (DTI) allows the analysis of changes in microstructure, through the quantification of the spread and direction of water molecules in tissues. We used fractional anisotropy (FA) maps to compare the integrity of WM between patients and controls. The objective of the present study was to investigate WM abnormalities in patients with frontal lobe epilepsy secondary to focal cortical dysplasia (FCD). Materials and Methods: We included 31 controls (12 women, 33.1?±?9.6?years, mean?±?SD) and 22 patients (11 women, 30.4?±?10.0?years), recruited from our outpatient clinic. They had clinical and EEG diagnosis of frontal lobe epilepsy, secondary to FCD detected on MRI. Patients and controls underwent 3T MRI, including the DTI sequence, obtained in 32 directions and b value of 1000?s/mm2. To process the DTI we used the following softwares: MRIcroN and FSL/TBSS (tract-based spatial statistics). We used a threshold-free cluster enhancement with significance at p?fasciculus (p?=?0.044), uncinate fasciculus, and inferior fronto-occipital fasciculus (p?=?0.042). Conclusion: Our results showed a widespread pattern of WM microstructural abnormalities extending beyond the main lesion seen on MRI (frontal lobe), which may be related to frequent seizures or to the extent of MRI-invisible portion of FCD.

Fonseca, Viviane de Carvalho; Yasuda, Clarissa Lin; Tedeschi, Guilherme Garlipp; Betting, Luiz Eduardo; Cendes, Fernando

2012-01-01

135

Disconnection Mechanism and Regional Cortical Atrophy Contribute to Impaired Processing of Facial Expressions and Theory of Mind in Multiple Sclerosis: A Structural MRI Study  

PubMed Central

Successful socialization requires the ability of understanding of others’ mental states. This ability called as mentalization (Theory of Mind) may become deficient and contribute to everyday life difficulties in multiple sclerosis. We aimed to explore the impact of brain pathology on mentalization performance in multiple sclerosis. Mentalization performance of 49 patients with multiple sclerosis was compared to 24 age- and gender matched healthy controls. T1- and T2-weighted three-dimensional brain MRI images were acquired at 3Tesla from patients with multiple sclerosis and 18 gender- and age matched healthy controls. We assessed overall brain cortical thickness in patients with multiple sclerosis and the scanned healthy controls, and measured the total and regional T1 and T2 white matter lesion volumes in patients with multiple sclerosis. Performances in tests of recognition of mental states and emotions from facial expressions and eye gazes correlated with both total T1-lesion load and regional T1-lesion load of association fiber tracts interconnecting cortical regions related to visual and emotion processing (genu and splenium of corpus callosum, right inferior longitudinal fasciculus, right inferior fronto-occipital fasciculus, uncinate fasciculus). Both of these tests showed correlations with specific cortical areas involved in emotion recognition from facial expressions (right and left fusiform face area, frontal eye filed), processing of emotions (right entorhinal cortex) and socially relevant information (left temporal pole). Thus, both disconnection mechanism due to white matter lesions and cortical thinning of specific brain areas may result in cognitive deficit in multiple sclerosis affecting emotion and mental state processing from facial expressions and contributing to everyday and social life difficulties of these patients.

Mike, Andrea; Strammer, Erzsebet; Aradi, Mihaly; Orsi, Gergely; Perlaki, Gabor; Hajnal, Andras; Sandor, Janos; Banati, Miklos; Illes, Eniko; Zaitsev, Alexander; Herold, Robert; Guttmann, Charles R. G.; Illes, Zsolt

2013-01-01

136

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

137

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

2011-01-01

138

No-scale ripple inflation revisited  

NASA Astrophysics Data System (ADS)

We revisit the no-scale ripple inflation model, where no-scale supergravity is modified by an additional term for the inflaton field in the Kähler potential. This term not only breaks one SU(N,1) symmetry explicitly, but also plays an important role for inflation. We generalize the superpotential in the no-scale ripple inflation model slightly. There exists a discrete Z2 symmetry/parity in the scalar potential in general, which can be preserved or violated by the non-canonical nomalized inflaton kinetic term. Thus, there are three inflation paths: one parity invariant path, and the left and right paths for parity violating scenario. We show that the inflations along the parity invariant path and right path are consistent with the Planck results. However, the gavitino mass for the parity invariant path is so large that the inflation results will be invalid if we consider the inflaton supersymmetry breaking soft mass term. Thus, only the inflation along the right path gives the correct and consistent results. Notably, the tensor-to-scalar ratio in such case can be large, with a value around 0.05, which may be probed by the future Planck experiment.

Li, Tianjun; Li, Zhijin; Nanopoulos, Dimitri V.

2014-04-01

139

Revisiting the relaxation dynamics of isolated pyrrole.  

PubMed

Herein, the interpretation of the femtosecond-scale temporal evolution of the pyrrole ion signal, after excitation in the 267-217 nm interval, recently published by our group [R. Montero, A. Peralta Conde, V. Ovejas, M. Fernández-Fernández, F. Castaño, J. R. Vázquez de Aldana, and A. Longarte, J. Chem. Phys. 137, 064317 (2012)] is re-visited. The observation of a shift in the pyrrole(+) transient respect to zero delay reference, initially attributed to ultrafast dynamics on the ??(*) type state (3s a1 ? ? 1a2), is demonstrated to be caused by the existence of pump + probe populated states, along the ionization process. The influence of these resonances in pump-prone ionization experiments, when multi-photon probes are used, and the significance of a proper zero-time reference, is discussed. The possibility of preparing the ??(*) state by direct excitation is investigated by collecting 1 + 1 photoelectron spectra, at excitation wavelengths ranging from 255 to 219 nm. No conclusive evidences of ionization through this state are found. PMID:25005285

Montero, Raúl; Ovejas, Virginia; Fernández-Fernández, Marta; Peralta Conde, Alvaro; Longarte, Asier

2014-07-01

140

Electromyogenic Artifacts and Electroencephalographic Inferences Revisited  

PubMed Central

Recent years have witnessed a renewed interest in using oscillatory brain electrical activity to understand the neural bases of cognition and emotion. Electrical signals originating from pericranial muscles represent a profound threat to the validity of such research. Recently, McMenamin et al (2010) examined whether independent component analysis (ICA) provides a sensitive and specific means of correcting electromyogenic (EMG) artifacts. This report sparked the accompanying commentary (Olbrich, Jödicke, Sander, Himmerich & Hegerl, in press), and here we revisit the question of how EMG can alter inferences drawn from the EEG and what can be done to minimize its pernicious effects. Accordingly, we briefly summarize salient features of the EMG problem and review recent research investigating the utility of ICA for correcting EMG and other artifacts. We then directly address the key concerns articulated by Olbrich and provide a critique of their efforts at validating ICA. We conclude by identifying key areas for future methodological work and offer some practical recommendations for intelligently addressing EMG artifact.

McMenamin, Brenton W.; Shackman, Alexander J.; Greischar, Lawrence L.; Davidson, Richard J.

2010-01-01

141

Nursing knowledge, theory and method revisited.  

PubMed

With the approach of the 21st century, nursing is having to respond to diverse influences which are remoulding the professional landscape. Not least of these is the changing status of western economies which underpins a drive towards evidence-based practice and an increased emphasis on multidisciplinary approaches to health care delivery. Certainty in health care is now a thing of the past. Central to the way the nursing profession embraces the future is its underlying philosophy: that which articulates professional values and shapes practice, research, education and management. In a time of change it is therefore essential to revisit the philosophical framework which underpins nursing. The debate in nursing research and theory appears to have stressed the polarization of viewpoints. It may be the case that feminist writers, ethnographers, positivist researchers and nursing theorists, in defending their own points of view, diminish rather than enhance professional dialogue. This paper reviews the nature of this debate within nursing and considers the implications that a dichotomous position may have for knowledge, theory and research method within the current context of health care. It then suggests a philosophical framework which could be relevant and accessible across the whole spectrum of nursing activity. In so doing, the paper aims to contribute to the discussion around epistemology and method in a way which encompasses the diversity found within the broad church of nursing. PMID:9354995

Booth, K; Kenrick, M; Woods, S

1997-10-01

142

Pair Production Constraints on Superluminal Neutrinos Revisited  

SciTech Connect

We revisit the pair creation constraint on superluminal neutrinos considered by Cohen and Glashow in order to clarify which types of superluminal models are constrained. We show that a model in which the superluminal neutrino is effectively light-like can evade the Cohen-Glashow constraint. In summary, any model for which the CG pair production process operates is excluded because such timelike neutrinos would not be detected by OPERA or other experiments. However, a superluminal neutrino which is effectively lightlike with fixed p{sup 2} can evade the Cohen-Glashow constraint because of energy-momentum conservation. The coincidence involved in explaining the SN1987A constraint certainly makes such a picture improbable - but it is still intrinsically possible. The lightlike model is appealing in that it does not violate Lorentz symmetry in particle interactions, although one would expect Hughes-Drever tests to turn up a violation eventually. Other evasions of the CG constraints are also possible; perhaps, e.g., the neutrino takes a 'short cut' through extra dimensions or suffers anomalous acceleration in matter. Irrespective of the OPERA result, Lorentz-violating interactions remain possible, and ongoing experimental investigation of such possibilities should continue.

Brodsky, Stanley J.; /SLAC; Gardner, Susan; /Kentucky U.

2012-02-16

143

[What mirror neurons have revealed: revisited].  

PubMed

The first paper on mirror neurons was published in 1992. In the span of over two decades since then, much knowledge about the relationship between social cognitive function and the motor control system has been accumulated. Direct matching of visual actions and their corresponding motor representations is the most important functional property of mirror neuron. Many studies have emphasized intrinsic simulation as a core concept for mirror neurons. Mirror neurons are thought to play a role in social cognitive function. However, the function of mirror neurons in the macaque remains unclear, because such cognitive functions are limited or lacking in macaque monkeys. It is therefore important to discuss these neurons in the context of motor function. Rizzolatti and colleagues have stressed that the most important function of mirror neurons in macaques is recognition of actions performed by other individuals. I suggest that mirror neurons in the Macaque inferior pariental lobule might be correlated with body schema. In the parieto-premotor network, matching of corollary discharge and actual sensory feedback is an essential neuronal operation. Recently, neurons showing mirror properties were found in some cortical areas outside the mirror neuron system. The current work would revisit the outcomes of mirror neuron studies to discuss the function of mirror neurons in the monkey. PMID:24899345

Murata, Akira; Maeda, Kazutaka

2014-06-01

144

Revisiting the phase diagram of hard ellipsoids.  

PubMed

In this work, the well-known Frenkel-Mulder phase diagram of hard ellipsoids of revolution [D. Frenkel and B. M. Mulder, Mol. Phys. 55, 1171 (1985)] is revisited by means of replica exchange Monte Carlo simulations. The method provides good sampling of dense systems and so, solid phases can be accessed without the need of imposing a given structure. At high densities, we found plastic solids and fcc-like crystals for semi-spherical ellipsoids (prolates and oblates), and SM2 structures [P. Pfleiderer and T. Schilling, Phys. Rev. E 75, 020402 (2007)] for x : 1-prolates and 1 : x-oblates with x ? 3. The revised fluid-crystal and isotropic-nematic transitions reasonably agree with those presented in the Frenkel-Mulder diagram. An interesting result is that, for small system sizes (100 particles), we obtained 2:1- and 1.5:1-prolate equations of state without transitions, while some order is developed at large densities. Furthermore, the symmetric oblate cases are also reluctant to form ordered phases. PMID:22482570

Odriozola, Gerardo

2012-04-01

145

The Non-Adiabatic Polaron Model Revisited  

NASA Astrophysics Data System (ADS)

We revisit Holstein's polaron model to derive an extension of the expression for the thermal dependence of the electrical resistivity in the non-adiabatic small-polaron regime. Our analysis relaxes Holstein's assumption that the vibrational-mode energies hbar ? k are much smaller than the thermal energy k B T and substitutes a fifth-order expansion in powers of hbar ? k/kBT for the linear approximation in the expression for the quasiparticle hopping probability in the original treatment. The resulting expression for the electrical resistivity has the form ?(T)=? 0 T 3/2 exp(E a /k B T-C/T 3+D/T 5), where C and D are constants related to the molecule-electron interaction energy, or alternatively to the polaron binding energy, and the dispersion relation of the vibrational normal modes. We show that experimental data for the La 1-x Ca x MnO 3 (x=0.30,0.34,0.40, and 0.45) manganite system, which are poorly fitted by the conventional non-adiabatic model, are remarkably well described by the more accurate expression. Our results suggest that, under conditions favoring high resistivity, the higher-order terms associated with the constants C and D in the above expression should taken into account in comparisons between theoretical and experimental results for the temperature-dependent transport properties of transition-metal oxides.

N. Ramirez, Fabian E.; Souza, José Antonio

2014-05-01

146

Revisiting the argument from fetal potential  

PubMed Central

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.

Manninen, Bertha Alvarez

2007-01-01

147

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

148

Revisiting the Trust Effect in Urban Elementary Schools  

ERIC Educational Resources Information Center

More than a decade after Goddard, Tschannen-Moran, and Hoy (2001) found that collective faculty trust in clients predicts student achievement in urban elementary schools, we sought to identify a plausible link for this relationship. Our purpose in revisiting the trust effect was twofold: (1) to test the main effect of collective faculty trust on…

Adams, Curt M.; Forsyth, Patrick B.

2013-01-01

149

Rural-Nonrural Disparities in Postsecondary Educational Attainment Revisited  

ERIC Educational Resources Information Center

Using data from the National Educational Longitudinal Study, this study revisited rural-nonrural disparities in educational attainment by considering a comprehensive set of factors that constrain and support youth's college enrollment and degree completion. Results showed that rural students were more advantaged in community social resources…

Byun, Soo-yong; Meece, Judith L.; Irvin, Matthew J.

2012-01-01

150

Threshold Concepts and Student Engagement: Revisiting Pedagogical Content Knowledge  

ERIC Educational Resources Information Center

This article revisits the notion that to facilitate quality learning requires teachers in higher education to have pedagogical content knowledge. It constructs pedagogical content knowledge as a teaching and learning space that brings content and pedagogy together. On the content knowledge side, it suggests that threshold concepts, akin to a…

Zepke, Nick

2013-01-01

151

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

152

Crop Classification Using Short-Revisit Multitemporal SAR Data  

Microsoft Academic Search

Classification of crops and other land cover types is an important application of both optical\\/infrared and SAR satel- lite data. It is already an import application of present satellite sys- tems, as it will be for planned missions, such as the Sentinels. An airborne SAR data set with a short revisit time acquired by the German ESAR system during the

Henning Skriver; Francesco Mattia; Giuseppe Satalino; Anna Balenzano; Valentijn R. N. Pauwels; Niko E. C. Verhoest; Malcolm Davidson

2011-01-01

153

WAC Revisited: You Get What You Pay for  

ERIC Educational Resources Information Center

In 1982, the author wrote an essay for the second issue of "The Writing Instructor," "Approaches to Comprehensive Writing: Integrating Writing into the College Curriculum," reviewing the early stages of the modern Writing Across the Curriculum (WAC)/Writing in the Disciplines (WID) movement. In this article, the author revisits his essay and…

Perelman, Les

2011-01-01

154

Children's Social Play Sequence: Parten's Classic Theory Revisited  

ERIC Educational Resources Information Center

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.…

Xu, Yaoying

2010-01-01

155

Discursivity, Heteroglossia, and Interest: Revisiting Herbert Kliebard's Dewey  

Microsoft Academic Search

This paper revisits Herbert Kliebard's figure of John Dewey in Kliebard's The Struggle for the American Curriculum. The paper argues that, while there are indeed reasons for the disembodied picture of Dewey that emerges from Struggle, such figuration ultimately has an effect that is overly reproductive: It ignores Dewey's efforts to live within and across institutional boundaries so as to

Kyle A. Greenwalt

2008-01-01

156

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

157

Facilitating Grade Acceleration: Revisiting the Wisdom of John Feldhusen  

ERIC Educational Resources Information Center

This article revisits the 1986 Feldhusen, Proctor, and Black recommendations on grade skipping. These recommendations originally appeared as 12 guidelines. In this article, the guidelines are grouped into three general categories: how to screen accelerant candidates, how to engage with the adults in the acceleration process (e.g., teachers,…

Culross, Rita R.; Jolly, Jennifer L.; Winkler, Daniel

2013-01-01

158

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

159

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

160

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 is…

Bates, Richard

2013-01-01

161

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

162

Stuck Schools Revisited: Beneath the Averages. K-12 Policy  

ERIC Educational Resources Information Center

"Stuck Schools Revisited: Beneath the Averages" shows why a national focus on turning around the lowest performing schools, while needed, is not enough to raise achievement and close gaps. The report analyzes student achievement data from Maryland and Indiana, which reflect the outcomes seen in other states. The results confirm a troubling…

Ushomirsky, Natasha

2011-01-01

163

The classification of glomerulonephritis in systemic lupus erythematosus revisited  

Microsoft Academic Search

The classification of glomerulonephritis in systemic lupus erythematosus revisited. The currently used classification reflects our understanding of the pathogenesis of the various forms of lupus nephritis, but clinicopathologic studies have revealed the need for improved categorization and terminology. Based on the 1982 classification published under the auspices of the World Health Organization (WHO) and subsequent clinicopathologic data, we propose that

Jan J. Weening; Vivette D. D'Agati; Melvin M. Schwartz; Surya V. Seshan; Charles E. Alpers; Gerald B. Appel; James E. Balow; Jan A. Bruijn; TERENCE COOK; FRANCO FERRARIO; Agnes B. Fogo; Ellen M. Ginzler; LEE HEBERT; GARY HILL; PRUE HILL; J. Charles Jennette; Norella C. Kong; PHILIPPE LESAVRE; MICHAEL LOCKSHIN; LAI-MENG LOOI; HIROFUMI MAKINO; Luiz A. Moura; MICHIO NAGATA

2004-01-01

164

Transport benchmarks for one-dimensional binary markovian mixtures revisited  

NASA Astrophysics Data System (ADS)

The classic benchmarks for transport through a binary markovian mixure are revisited to look at the probability distribution function of the chosen "results": reflection, transmission and scalar flux. We argue that knowledge of the ensemble averaged results is not sufficient for reliable predictions: a measure of the dispersion must also be obtained. An algorithm to estimate this dispersion is tested.

Malvagi, Fausto

2014-06-01

165

White matter structure and symptom dimensions in obsessive-compulsive disorder.  

PubMed

There is evidence that the different symptom dimensions in obsessive-compulsive disorder (OCD) may be mediated by partially distinct neural systems. This DTI study investigated the relationship between symptom dimensions and white matter microstructure. Fractional anisotropy (FA), axial and radial diffusivity was analyzed in relation to the main OCD symptom dimensions. Symptom severity on the obsessing dimension was negatively correlated with FA in the corpus callosum and the cingulate bundle. Severity on the ordering dimension was negatively correlated with FA in, amongst others, the right inferior fronto-occipital fasciculus and the right optic radiation. All correlations were ascribable to alterations in radial diffusivity while there was no association between symptoms and axial diffusivity. Present results illustrate an association between alterations in visual processing tracts and ordering symptoms which are characterized by altered visual processing and increased attention towards irrelevant detail. They also indicate an association between obsessive thoughts and alterations in structures known to be relevant for cognitive control and inhibition. Hence, different symptom dimensions must be taken into account in order to disentangle the neurobiological underpinnings of OCD. PMID:22099866

Koch, Kathrin; Wagner, Gerd; Schachtzabel, Claudia; Schultz, C Christoph; Straube, Thomas; Güllmar, Daniel; Reichenbach, Jürgen R; Peikert, Gregor; Sauer, Heinrich; Schlösser, Ralf G M

2012-02-01

166

White Matter Integrity is Reduced in Bulimia Nervosa  

PubMed Central

Objective To investigate brain white matter (WM) functionality in bulimia nervosa (BN) in relation to anxiety. Method Twenty-one control (CW, mean age 27±7 years) and 20 BN women (mean age 25±5 years) underwent brain diffusion tensor imaging (DTI) to measure fractional anisotropy (FA; an indication of WM axon integrity) and the apparent diffusion coefficient (ADC; reflecting WM cell damage). Results FA was decreased in BN in the bilateral corona radiata extending into the posterior limb of the internal capsule, the corpus callosum, the right sub-insular white matter and right fornix. In CW but not BN trait anxiety correlated negatively with fornix, corpus callosum and left corona radiata FA. ADC was increased in BN compared to CW in the bilateral corona radiata, corpus callosum, inferior fronto-occipital and uncinate fasciculus. Alterations in BN WM functionality were not due to structural brain alterations. Discussion WM integrity is disturbed in BN, especially in the corona radiate, which has been associated with taste and brain reward processing. Whether this is a premorbid condition or an effect from the illness is yet uncertain. The relationships between WM FA and trait anxiety in CW but not BN may suggest that altered WM functionality contributes to high anxious traits in BN.

Mettler, Lisa N.; Shott, Megan E.; Pryor, Tamara; Yang, Tony T.; Frank, Guido K.W.

2013-01-01

167

Altered fimbria-fornix white matter integrity in anorexia nervosa predicts harm avoidance  

PubMed Central

The eating disorder anorexia nervosa (AN) is associated with high anxiety. The brain mechanisms that drive those behaviors are unknown. In this study we wanted to test whether brain WM integrity is altered in AN, and related to heightened anxiety. Sixteen adult women with AN (mean age 24±7 years) and 17 healthy control women (CW, mean age 25±4 years) underwent diffusion tensor imaging (DTI) of the brain. The DTI brain images were used to calculate the fractional anisotropy (FA) of WM tracts, which is a measure for WM integrity. AN individuals compared to CW showed clusters of significantly reduced FA (p<0.05, corrected) in the bilateral fimbria-fornix, fronto-occipital fasciculus, as well as posterior cingulum WM. In the AN group, Harm Avoidance was predicted by left (F=5.8, Beta=?0.54, p<0.03) and right (F=6.0, Beta=?0.55, p<0.03) fimbria-fornix FA. Those findings were not due to WM volume deficits in AN. This study indicates that WM integrity is abnormal in AN in limbic and association pathways, which could contribute to disturbed feeding, emotion processing and body perception in AN. The prediction of Harm Avoidance in AN by fimbria-fornix WM integrity suggests that this pathway may be mechanistically involved in high anxiety in AN.

Kazlouski, Demitry; Rollin, Michael D.H.; Tregellas, Jason; Shott, Megan E.; Jappe, Leah M.; Hagman, Jennifer O.; Pryor, Tamara; Yang, Tony T.; Frank, Guido K.W.

2011-01-01

168

Altered fimbria-fornix white matter integrity in anorexia nervosa predicts harm avoidance.  

PubMed

The eating disorder anorexia nervosa (AN) is associated with high anxiety. The brain mechanisms that drive those behaviors are unknown. In this study we wanted to test whether brain white matter (WM) integrity is altered in AN, and related to heightened anxiety. Sixteen adult women with AN (mean age 24 ± 7 years) and 17 healthy control women (CW, mean age 25 ± 4 years) underwent diffusion tensor imaging (DTI) of the brain. The DTI brain images were used to calculate the fractional anisotropy (FA) of WM tracts, which is a measure for WM integrity. AN individuals compared to CW showed clusters of significantly reduced FA (p<0.05, corrected) in the bilateral fimbria-fornix and the fronto-occipital fasciculus, as well as the posterior cingulum WM. In the AN group, Harm Avoidance was predicted by FA in the left and right fimbria-fornix. Those findings were not due to WM volume deficits in AN. This study indicates that WM integrity is abnormal in AN in limbic and association pathways, which could contribute to disturbed feeding, emotion processing and body perception in AN. The prediction of Harm Avoidance in AN by fimbria-fornix WM integrity suggests that this pathway may be mechanistically involved in high anxiety in AN. PMID:21498054

Kazlouski, Demitry; Rollin, Michael D H; Tregellas, Jason; Shott, Megan E; Jappe, Leah M; Hagman, Jennifer O; Pryor, Tamara; Yang, Tony T; Frank, Guido K W

2011-05-31

169

The coordinate coherent states approach revisited  

SciTech Connect

We revisit the coordinate coherent states approach through two different quantization procedures in the quantum field theory on the noncommutative Minkowski plane. The first procedure, which is based on the normal commutation relation between an annihilation and creation operators, deduces that a point mass can be described by a Gaussian function instead of the usual Dirac delta function. However, we argue this specific quantization by adopting the canonical one (based on the canonical commutation relation between a field and its conjugate momentum) and show that a point mass should still be described by the Dirac delta function, which implies that the concept of point particles is still valid when we deal with the noncommutativity by following the coordinate coherent states approach. In order to investigate the dependence on quantization procedures, we apply the two quantization procedures to the Unruh effect and Hawking radiation and find that they give rise to significantly different results. Under the first quantization procedure, the Unruh temperature and Unruh spectrum are not deformed by noncommutativity, but the Hawking temperature is deformed by noncommutativity while the radiation specturm is untack. However, under the second quantization procedure, the Unruh temperature and Hawking temperature are untack but the both spectra are modified by an effective greybody (deformed) factor. - Highlights: Black-Right-Pointing-Pointer Suggest a canonical quantization in the coordinate coherent states approach. Black-Right-Pointing-Pointer Prove the validity of the concept of point particles. Black-Right-Pointing-Pointer Apply the canonical quantization to the Unruh effect and Hawking radiation. Black-Right-Pointing-Pointer Find no deformations in the Unruh temperature and Hawking temperature. Black-Right-Pointing-Pointer Provide the modified spectra of the Unruh effect and Hawking radiation.

Miao, Yan-Gang, E-mail: miaoyg@nankai.edu.cn; Zhang, Shao-Jun, E-mail: sjzhang@mail.nankai.edu.cn

2013-02-15

170

Alkaline phosphatase revisited: hydrolysis of alkyl phosphates.  

PubMed

Escherichia coli alkaline phosphatase (AP) is the prototypical two metal ion catalyst with two divalent zinc ions bound approximately 4 A apart in the active site. Studies spanning half a century have elucidated many structural and mechanistic features of this enzyme, rendering it an attractive model for investigating the potent catalytic power of bimetallic centers. Unfortunately, fundamental mechanistic features have been obscured by limitations with the standard assays. These assays generate concentrations of inorganic phosphate (P(i)) in excess of its inhibition constant (K(i) approximately 1 muM). This tight binding by P(i) has affected the majority of published kinetic constants. Furthermore, binding limits k(cat)/K(m) for reaction of p-nitrophenyl phosphate, the most commonly employed substrate. We describe a sensitive (32)P-based assay for hydrolysis of alkyl phosphates that avoids the complication of product inhibition. We have revisited basic mechanistic features of AP with these alkyl phosphate substrates. The results suggest that the chemical step for phosphorylation of the enzyme limits k(cat)/K(m). The pH-rate profile and additional results suggest that the serine nucleophile is active in its anionic form and has a pK(a) of < or = 5.5 in the free enzyme. An inactivating pK(a) of 8.0 is observed for binding of both substrates and inhibitors, and we suggest that this corresponds to ionization of a zinc-coordinated water molecule. Counter to previous suggestions, inorganic phosphate dianion appears to bind to the highly charged AP active site at least as strongly as the trianion. The dependence of k(cat)/K(m) on the pK(a) of the leaving group follows a Brønsted correlation with a slope of beta(lg) = -0.85 +/- 0.1, differing substantially from the previously reported value of -0.2 obtained from data with a less sensitive assay. This steep leaving group dependence is consistent with a largely dissociative transition state for AP-catalyzed hydrolysis of phosphate monoesters. The new (32)P-based assay employed herein will facilitate continued dissection of the AP reaction by providing a means to readily follow the chemical step for phosphorylation of the enzyme. PMID:11863460

O'Brien, Patrick J; Herschlag, Daniel

2002-03-01

171

Finite frequency tomography: the checkerboard test revisited  

NASA Astrophysics Data System (ADS)

We address some consequences of the application of finite frequency theory for seismic tomography by revisiting the classical checkerboard test. We use a simple borehole-to-borehole experiment set-up in order to have complete control of the situation and to avoid complicating factors such as crustal corrections that still hamper global tomography. We are particularly interested in the feasibility of using ray-based finite frequency kernels in the inversion of travel time perturbations measured by crosscorrelation, in the cross-dependence between S wave velocity perturbations and the measured P travel times, and in the benefits of using finite-frequency theory on one or multiple frequency bands. We have done a 3D checkerboard test to assess the influence of these issues. Full-waveform synthetic seismograms are calculated using the spectral elements method up to 2 kHz maximum frequency. The computational domain extends 200 m x 120 m x 120 m and the target velocity model is a checkerboard with 12 m x 12 m x 12 m blocks of velocities 5% slower and faster than the background (homogeneous, Vp=6 km/s) model. First, we make a comparison between finite-frequency kernels calculated by ray theory with those based on the spectral elements method (adjoint technique), in terms of resolution, accuracy, but also computational cost. From synthetic seismograms calculated for the 3D checkerboard model as well as for the homogeneous model, we measure crosscorrelation travel times at different frequency bands and invert them with classical ray theory as well as with finite frequency theory. Several interesting features are highlighted in our multi-band data set, such as the wavefront healing effect. For instance, we observe that the delay times, in absolute value, are usually larger at short (0.5 ms) than long (4 ms) periods. This can be explained by the presence of the "doughnut hole" along the geometrical ray path in the sensitivity kernels, whose diameter is proportional to the period. Thus, as the period increases, the anomalies are able to "hide" inside the growing "doughnut hole". When a single frequency band is interpreted using ray theory (infinite frequency approximation), the fact that wavefront healing is not taken into account has a disastrous effect, in particular on the imaging of blocks that are somewhat smaller than the Fresnel zone. When interpreting the same data set with finite-frequency theory we do much better, especially in the center of the model where Fresnel zones are widest. Adding a range of frequencies in the inversion (i.e. taking body wave dispersion into account) significantly increases resolution.

Mercerat, E. D.; Zaroli, C.; Nolet, G.

2011-12-01

172

The hard-core model on random graphs revisited  

NASA Astrophysics Data System (ADS)

We revisit the classical hard-core model, also known as independent set and dual to vertex cover problem, where one puts particles with a first-neighbor hard-core repulsion on the vertices of a random graph. Although the case of random graphs with small and very large average degrees respectively are quite well understood, they yield qualitatively different results and our aim here is to reconciliate these two cases. We revisit results that can be obtained using the (heuristic) cavity method and show that it provides a closed-form conjecture for the exact density of the densest packing on random regular graphs with degree K >= 20, and that for K > 16 the nature of the phase transition is the same as for large K. This also shows that the hard-code model is the simplest mean-field lattice model for structural glasses and jamming.

Barbier, Jean; Krzakala, Florent; Zdeborová, Lenka; Zhang, Pan

2013-12-01

173

The Transverse Momentum Dependent Statistical Parton Distributions Revisited  

NASA Astrophysics Data System (ADS)

The extension of the statistical parton distributions to include their transverse momentum dependence (TMD) is revisited by considering that the proton target has a finite longitudinal momentum. The TMD will be generated by means of a transverse energy sum rule. The new results are mainly relevant for electron-proton inelastic collisions in the low Q2 region. We take into account the effects of the Melosh-Wigner rotation for the helicity distributions.

Bourrely, Claude; Buccella, Franco; Soffer, Jacques

2013-04-01

174

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

175

Hadronization revisited: the dynamics behind hadro-chemical equilibrium  

Microsoft Academic Search

The multiplicity of hadronic species created in elementary, and in nucleus-nucleus collisions, are known to be well reproduced by the statistical hadronization model, in its canonical and grand-canonical versions.To understand the origin of the implied equilibrium we revisit the hadronization models developed for e+e- annihilation to hadrons which imply spatial color pre-confinement clusters forming at the end of the pQCD

Reinhard Stock

2007-01-01

176

Anatomo-functional study of the temporo-parieto-occipital region: dissection, tractographic and brain mapping evidence from a neurosurgical perspective.  

PubMed

The temporo-parieto-occipital (TPO) junction is a complex brain territory heavily involved in several high-level neurological functions, such as language, visuo-spatial recognition, writing, reading, symbol processing, calculation, self-processing, working memory, musical memory, and face and object recognition. Recent studies indicate that this area is covered by a thick network of white matter (WM) connections, which provide efficient and multimodal integration of information between both local and distant cortical nodes. It is important for neurosurgeons to have good knowledge of the three-dimensional subcortical organisation of this highly connected region to minimise post-operative permanent deficits. The aim of this dissection study was to highlight the subcortical functional anatomy from a topographical surgical perspective. Eight human hemispheres (four left, four right) obtained from four human cadavers were dissected according to Klingler's technique. Proceeding latero-medially, the authors describe the anatomical courses of and the relationships between the main pathways crossing the TPO. The results obtained from dissection were first integrated with diffusion tensor imaging reconstructions and subsequently with functional data obtained from three surgical cases, all resection of infiltrating glial tumours using direct electrical mapping in awake patients. The subcortical limits for performing safe lesionectomies within the TPO region are as follows: within the parietal region, the anterior horizontal part of the superior longitudinal fasciculus and, more deeply, the arcuate fasciculus; dorsally, the vertical projective thalamo-cortical fibres. For lesions located within the temporal and occipital lobes, the resection should be tailored according to the orientation of the horizontal associative pathways (the inferior fronto-occipital fascicle, inferior longitudinal fascicle and optic radiation). The relationships between the WM tracts and the ventricle system were also examined. These results indicate that a detailed anatomo-functional awareness of the WM architecture within the TPO area is mandatory when approaching intrinsic brain lesions to optimise surgical results and to minimise post-operative morbidity. PMID:24975421

De Benedictis, Alessandro; Duffau, Hugues; Paradiso, Beatrice; Grandi, Enrico; Balbi, Sergio; Granieri, Enrico; Colarusso, Enzo; Chioffi, Franco; Marras, Carlo Efisio; Sarubbo, Silvio

2014-08-01

177

A combined DTI and structural MRI study in medicated-naïve chronic schizophrenia.  

PubMed

Disconnection in white matter (WM) pathway and alterations in gray matter (GM) structure have been hypothesized as pathogenesis in schizophrenia. However, the relationship between the abnormal WM integrity and the alteration of GM in anatomically connected areas remains uncertain. Moreover, the potential influence of antipsychotic medication on WM anisotropy and cortical morphology was not excluded in previous studies. In this study, a total number of 34 subjects were enrolled, including 17 medicated-naïve chronic schizophrenia patients and 17 healthy controls. Tract-based spatial statistics (TBSS) were applied to investigate the level of WM integrity. The FreeSurfer surface-based analysis was used to determine GM volume, cortical thickness and the surface area of GM regions which corresponded to abnormal WM fiber tracts. We observed that patients possessed lower fractional anisotropy (FA) values in the left inferior fronto-occipital fasciculus (IFOF) and left inferior longitudinal fasciculus (ILF), along with smaller GM volume and cortical thinning in temporal lobe than the healthy controls, which reflected the underlying WM and GM disruption that contributed to the disease. In the patient population, the lower connectivity of ILF and IFOF was positively associated with cortical thickness in left lateral orbitofrontal cortex, superior temporal gyrus and lingual gyrus in males, and positively correlated with GM volume in left lateral orbitofrontal cortex in females. On the other hand, it was negatively correlated with cortical area of middle temporal gyrus in males and temporal pole in females respectively, but not when genders were combined. These findings suggested that abnormal WM integrity and anatomical correspondence of GM alterations in schizophrenia were interdependent on gender-separated analysis in patients with schizophrenia. Moreover, combining TBSS and FreeSurfer might be a useful method to provide significant insight into interacting processes related to WM fiber tracts and GM changes in schizophrenia. PMID:24161847

Liu, Xiaoyi; Lai, Yunyao; Wang, Xijin; Hao, Chuanxi; Chen, Lei; Zhou, Zhenyu; Yu, Xin; Hong, Nan

2014-01-01

178

Reading skill in adult survivors of childhood brain tumor: A theory-based neurocognitive model.  

PubMed

Objective: This study investigated the relationship between word reading and white matter (WM) integrity within a neuroanatomical-based reading system comparing adult survivors of childhood brain tumors and controls. It was predicted that the association between WM integrity and word reading would be mediated by processing speed, and this indirect effect would be moderated by group. Method: Thirty-seven adult survivors of childhood brain tumor and typically developing adults participated (age M = 24.19 ± 4.51 years, 62% female). DTI Tractography identified the WM tract for 3 of the reading system connections: inferior fronto-occipital fasciculus (IFOF), arcuate fasciculus (AF), and parietotemporal-occipitotemporal connection (PT-OT). Results: Fractional anisotropy values (FA) of the PT-OT tract were significantly correlated with word reading in survivors and controls (r = .45, .58, respectively; p < .05) and IFOF values were associated with reading in survivors only (r = .59, p < .01). Further, the moderated mediated model was significant for PT-OT and IFOF, such that the indirect effect of processing speed was only present for survivors (CI: PT-OT: 2.90, 28.41, IFOF: 2.92, 40.17). Conclusion: Results suggest the tracts emerging from the occipitotemporal area are a critical component of the reading system in adults. The finding that processing speed was the mechanism by which WM was associated with reading in survivors is in alignment with the developmental cascade model. Current findings bolster the existing theory-based models of reading using innovative diffusion tensor imaging and moderated mediation statistical neurodevelopmental model, establishing the role of processing speed and specific WM pathway integrity in word reading skill. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24548126

Smith, Kristen M; King, Tricia Z; Jayakar, Reema; Morris, Robin D

2014-05-01

179

Neuroanatomical Correlates of Developmental Dyscalculia: Combined Evidence from Morphometry and Tractography  

PubMed Central

Poor mathematical abilities adversely affect academic and career opportunities. The neuroanatomical basis of developmental dyscalculia (DD), a specific learning deficit with prevalence rates exceeding 5%, is poorly understood. We used structural MRI and diffusion tensor imaging (DTI) to examine macro- and micro-structural impairments in 7- to 9-year-old children with DD, compared to a group of typically developing (TD) children matched on age, gender, intelligence, reading abilities and working memory capacity. Voxel-based morphometry (VBM) revealed reduced grey matter (GM) bilaterally in superior parietal lobule, intra-parietal sulcus, fusiform gyrus, parahippocampal gyrus and right anterior temporal cortex in children with DD. VBM analysis also showed reduced white matter (WM) volume in right temporal-parietal cortex. DTI revealed reduced fractional anisotropy (FA) in this WM region, pointing to significant right hemisphere micro-structural impairments. Furthermore, FA in this region was correlated with numerical operations but not verbal mathematical reasoning or word reading. Atlas-based tract mapping identified the inferior longitudinal fasciculus, inferior fronto-occipital fasciculus and caudal forceps major as key pathways impaired in DD. DTI tractography suggests that long-range WM projection fibers linking the right fusiform gyrus with temporal-parietal WM are a specific source of vulnerability in DD. Network and classification analysis suggest that DD in children may be characterized by multiple dysfunctional circuits arising from a core WM deficit. Our findings link GM and WM abnormalities in children with DD and they point to macro- and micro-structural abnormalities in right hemisphere temporal-parietal WM, and pathways associated with it, as key neuroanatomical correlates of DD.

Rykhlevskaia, Elena; Uddin, Lucina Q.; Kondos, Leeza; Menon, Vinod

2009-01-01

180

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

PubMed Central

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 FA 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 results reproducibility. 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.

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

2012-01-01

181

Novel DTI Methodology to Detect and Quantify Injured Regions and Affected Brain Pathways in Traumatic Brain Injury  

PubMed Central

Purpose To develop and apply DTI based normalization methodology for the detection and quantification of traumatic brain injury (TBI) and the impact of injury along specific brain pathways in: a) individual TBI subjects, and b) a TBI group. Materials and Methods Normalized DTI tractography was conducted in the native space of 12 TBI and 10 age-matched control subjects using the same number of seeds in each subject, distributed at anatomically equivalent locations. Whole-brain tracts from the control group were mapped onto the head of each TBI subject. Differences in the Fractional Anisotropy (FA) maps between each TBI subject and the control group were computed in a common space using a t-test, transformed back to the individual TBI subject's head-space, and thresholded to form Regions of Interest (ROIs) that were used to sort tracts from the control group and the individual TBI subject. Tract-counts for a given ROI in each TBI subject were compared to group mean for the same ROI to quantify impact of injury along affected pathways. Same procedure was used to compare TBI group to control group in a common space. Results Sites of injury within individual TBI subjects and affected pathways included hippocampal/fornix, inferior fronto-occipital, inferior longitudinal fasciculus, corpus callosum (genu and splenium), cortico-spinal tracts and the uncinate fasciculus. Most of these regions were also detected in the group study. Conclusions The DTI normalization methodology presented here enables automatic delineation of ROIs within the heads of individual subjects (or in a group). These ROIs not only localize and quantify the extent of injury, but also quantify the impact of injury on affected pathways in an individual or a group of TBI subjects.

Singh, Manbir; Jeong, Jeongwon; Hwang, Darryl; Sungkarat, Witaya; Gruen, Peter

2009-01-01

182

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

183

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

184

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

185

Entropy of measurement and erasure: Szilard's membrane model revisited  

NASA Astrophysics Data System (ADS)

It is widely believed that measurement is accompanied by irreversible entropy increase. This conventional wisdom is based in part on Szilard's 1929 study of entropy decrease in a thermodynamic system by intelligent intervention (i.e., a Maxwell's demon) and Brillouin's association of entropy with information. Bennett subsequently argued that information acquisition is not necessarily irreversible, but information erasure must be dissipative (Landauer's principle). Inspired by the ensuing debate, we revisit the membrane model introduced by Szilard and find that it can illustrate and clarify (1) reversible measurement, (2) information storage, (3) decoupling of the memory from the system being measured, and (4) entropy increase associated with memory erasure and resetting.

Leff, Harvey S.; Rex, Andrew F.

1994-11-01

186

Chaos control: The problem of a bouncing ball revisited  

NASA Astrophysics Data System (ADS)

The problem of a body bouncing on a periodically oscillating surface is revisited to demonstrate chaos control. When the bouncing body is magnetic, it is possible to modify its behavior by adding a magnetic driving force. The mechanism of chaos control may be understood by means of a mechanical analysis which shows that the main result of applying the driving force is to shift the bifurcation diagram in such a way that chaotic behavior is replaced by periodic behavior and vice versa. A simple experiment is presented, along with a numerical simulation, that provides insight into chaos control.

Vargas, M. Cristina; Huerta, D. A.; Sosa, Victor

2009-09-01

187

[Perinatal risk at term and post-term revisited].  

PubMed

The aim of this review was to revisit the evaluation of risk of foetal and neonatal mortality at term. We analyse the meaning of term period and difficulty to determine the normal duration of the pregnancy. Specific complications associated with post term and the statistic approach of the perinatal risk are analysed, together with various mortality rates and especially the prospective risk introducing foetal term as a new concept. We study various aspect and evolution of non specific morbidity of the term period. An optimal decision for term management should involve pregnant women and the analysed parameters should be taken into consideration. PMID:17537588

Vercoustre, L; Nizard, J

2007-11-01

188

Strategist and the Web Revisited: An Updated Guide to Internet Resources.  

National Technical Information Service (NTIS)

The authors revisit the Internet (Web) to update their guide for planners and researchers interested in the practice, problems, and policies of contemporary national security and military strategy. As with the previous version, the authors conclude that w...

J. Kievit S. Metz

1996-01-01

189

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

190

Neuromodulator threading: revisiting an approach to neurotoxin delivery.  

PubMed

Neuromodulator toxins are traditionally delivered to facial muscles via a depot technique using a 32g needle. This article revisits the threading technique, which was used more commonly in the 1990s and early 2000s prior to the introduction of the 32g x ½" gamma ray sterilized needle. A description of the threading technique, illustrated by diagrams and patient photos, is presented for the orbicularis oris and corrugator supercilii injection sites. In contrast to the depot technique in which the needle enters the skin at a 90-degree angle, the threading technique enters the skin at a 20- to 30-degree angle. Specifically, for the orbicularis oris, onabotulinum toxin A injections are performed 2 to 5mm beyond the "white roll" of the vermillion border. After the needle punctures the skin, the toxin is injected while withdrawing in a threading manner parallel to the vermillion border. This method is repeated along the entire length of the orbicularis oris muscle. For the corrugator supercilii muscles, the injection technique differs slightly. A depot injection is given at the most medial point of the muscle, targeting the body of the muscle. The tail of the corrugator supercilii is injected using the threading technique as described for the orbicularis oris, in which the needle inserts at a 20- to 30-degree angle. This paper revisits the threading injection technique for neurotoxin treatment of the orbicularis and corrugator supercilii sites. PMID:25013538

Higgins, H William; Lee, Kachiu C; Enzer, Yoash

2014-06-01

191

Word learning is mediated by the left arcuate fasciculus  

PubMed Central

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.

Lopez-Barroso, Diana; Catani, Marco; Ripolles, Pablo; Dell'Acqua, Flavio; Rodriguez-Fornells, Antoni; de Diego-Balaguer, Ruth

2013-01-01

192

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

193

Response variance in functional maps: neural darwinism revisited.  

PubMed

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. PMID:23874733

Takahashi, Hirokazu; Yokota, Ryo; Kanzaki, Ryohei

2013-01-01

194

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

195

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

196

Neutrino dark energy-revisiting the stability issue  

SciTech Connect

A coupling between a light scalar field and neutrinos has been widely discussed as a mechanism for linking (time varying) neutrino masses and the present energy density and equation of state of dark energy. However, it has been pointed out that the viability of this scenario in the non-relativistic neutrino regime is threatened by the strong growth of hydrodynamic perturbations associated with a negative adiabatic sound speed squared. In this paper we revisit the stability issue in the framework of linear perturbation theory in a model independent way. The criterion for the stability of a model is translated into a constraint on the scalar-neutrino coupling, which depends on the ratio of the energy densities in neutrinos and cold dark matter. We illustrate our results by providing meaningful examples for both stable and unstable models.

Bjaelde, Ole Eggers; Hannestad, Steen [Department of Physics and Astronomy, University of Aarhus, Ny Munkegade, DK-8000 Aarhus C (Denmark); Brookfield, Anthony W; Van de Bruck, Carsten [Department of Applied Mathematics, Astro-Particle Theory and Cosmology Group, Hounsfield Road, Hicks Building, University of Sheffield, Sheffield S3 7RH (United Kingdom); Mota, David F [Institute for Theoretical Physics, University of Heidelberg, D-69120 Heidelberg (Germany); Schrempp, Lily [Deutsches Elektron-Synchroton DESY, Hamburg, Notkestrasse 85, 22607 Hamburg (Germany); Tocchini-Valentini, Domenico, E-mail: oeb@phys.au.dk, E-mail: php04awb@sheffield.ac.uk, E-mail: C.vandebruck@sheffield.ac.uk, E-mail: sth@phys.au.dk, E-mail: d.mota@thphys.uni-heidelberg.de, E-mail: lily.schrempp@desy.de, E-mail: dtv@skysrv.pha.jhu.edu [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

2008-01-15

197

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

198

Feedback instability in the magnetosphere-ionosphere coupling system: Revisited  

SciTech Connect

A coupled set of the reduced magnetohydrodynamic and the two-fluid equations is applied to the magnetosphere-ionosphere (M-I) feedback interactions in relation to growth of quite auroral arcs. A theoretical analysis revisiting the linear feedback instability reveals asymptotic behaviors of the dispersion relation and a non-Hermite property in the M-I coupling. A nonlinear simulation of the feedback instability in the M-I coupling system manifests growth of the Kelvin-Helmholtz-like mode in the magnetosphere as the secondary instability. The distorted vortex and field-aligned current profiles propagating as the shear Alfven waves lead to spontaneous deformation of ionospheric density and current structures associated with auroral arcs.

Watanabe, T.-H. [National Institute for Fusion Science/Graduate University for Advanced Studies, Toki, Gifu, 509-5292 (Japan)

2010-02-15

199

Atlas-based white matter analysis in individuals with velo-cardio-facial syndrome (22q11.2 deletion syndrome) and unaffected siblings  

PubMed Central

Background Velo-cardio-facial syndrome (VCFS, MIM#192430, 22q11.2 Deletion Syndrome) is a genetic disorder caused by a deletion of about 40 genes at the q11.2 band of one copy of chromosome 22. Individuals with VCFS present with deficits in cognition and social functioning, high risk of psychiatric disorders, volumetric reductions in gray and white matter (WM) and some alterations of the WM microstructure. The goal of the current study was to characterize the WM microstructural differences in individuals with VCFS and unaffected siblings, and the correlation of WM microstructure with neuropsychological performance. We hypothesized that individuals with VCFS would have decreased indices of WM microstructure (fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD)), particularly in WM tracts to the frontal lobe, and that these measures would be correlated with cognitive functioning. Methods Thirty-three individuals with VCFS (21 female) and 16 unaffected siblings (8 female) participated in DTI scanning and neuropsychological testing. We performed an atlas-based analysis, extracted FA, AD, and RD measures for 54 WM tracts (27 in each hemisphere) for each participant, and used MANOVAs to compare individuals with VCFS to siblings. For WM tracts that were statistically significantly different between VCFS and siblings (pFDR?fasciculus, and decreased AD in multiple WM tracts (bilateral superior and posterior corona radiata, dorsal cingulum, inferior fronto-occipital fasciculus, superior longitudinal fasciculus, superior cerebellar peduncle, posterior thalamic radiation, and left anterior corona radiata, retrolenticular part of the internal capsule, external capsule, sagittal stratum). We also found significant correlations of AD with measures of executive function, IQ, working memory, and/or social cognition. Conclusions Our results suggest that individuals with VCFS display abnormal WM connectivity in a widespread cerebro-anatomical network, involving tracts from/to all cerebral lobes and the cerebellum. Future studies could focus on the WM developmental trajectory in VCFS, the association of WM alterations with psychiatric disorders, and the effects of candidate 22q11.2 genes on WM anomalies.

2012-01-01

200

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

201

Neuroanatomical Changes due to Hearing Loss and Chronic Tinnitus: A Combined VBM and DTI Study  

PubMed Central

Subjective tinnitus is the perception of sound in the absence of an external source. Tinnitus is often accompanied by hearing loss but not everyone with hearing loss experiences tinnitus. We examined neuroanatomical alterations associated with hearing loss and tinnitus in three groups of subjects: those with hearing loss with tinnitus, those with hearing loss without tinnitus and normal hearing controls without tinnitus. To examine changes in gray matter we used structural MRI scans and voxel-based morphometry (VBM) and to identify changes in white matter tract orientation we used diffusion tensor imaging (DTI). A major finding of our study was that there were both gray and white matter changes in the vicinity of the auditory cortex for subjects with hearing loss alone relative to those with tinnitus and those with normal hearing. We did not find significant changes in gray or white matter in subjects with tinnitus and hearing loss compared to normal hearing controls. VBM analysis revealed that individuals with hearing loss without tinnitus had gray matter decreases in anterior cingulate and superior and medial frontal gyri relative to those with hearing loss and tinnitus. Region-of-interest analysis revealed additional decreases in superior temporal gyrus for the hearing loss group compared to the tinnitus group. Investigating effects of hearing loss alone, we found gray matter decreases in superior and medial frontal gyri in participants with hearing loss compared to normal hearing controls. DTI analysis showed decreases in fractional anisotropy values in the right superior and inferior longitudinal fasciculi, corticospnial tract, inferior fronto-occipital tract, superior occipital fasciculus, and anterior thalamic radiation for the hearing loss group relative to normal hearing controls. In attempting to dissociate the effect of tinnitus from hearing loss, we observed that hearing loss rather than tinnitus had the greatest influence on gray and white matter alterations.

Husain, Fatima T.; Medina, Roberto E.; Davis, Caroline W.; Szymko-Bennett, Yvonne; Simonyan, Kristina; Pajor, Nathan M.; Horwitz, Barry

2010-01-01

202

White matter abnormalities in pediatric obsessive-compulsive disorder.  

PubMed

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. PMID:22871914

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

2012-11-01

203

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

204

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

2013-02-01

205

Neuroanatomical pattern classification in a population-based sample of first-episode schizophrenia.  

PubMed

Recent neuroanatomical pattern classification studies have attempted to individually classify cases with psychotic disorders using morphometric MRI data in an automated fashion. However, this approach has not been tested in population-based samples, in which variable patterns of comorbidity and disease course are typically found. We aimed to evaluate the diagnostic accuracy (DA) of the above technique to discriminate between incident cases of first-episode schizophrenia identified in a circumscribed geographical region over a limited period of time, in comparison with next-door healthy controls. Sixty-two cases of first-episode schizophrenia or schizophreniform disorder and 62 age, gender and educationally-matched controls underwent 1.5 T MRI scanning at baseline, and were naturalistically followed-up over 1 year. T1-weighted images were used to train a high-dimensional multivariate classifier, and to generate both spatial maps of the discriminative morphological patterns between groups and ROC curves. The spatial map discriminating first-episode schizophrenia patients from healthy controls revealed a complex pattern of regional volumetric abnormalities in the former group, affecting fronto-temporal-occipital gray and white matter regions bilaterally, including the inferior fronto-occipital fasciculus, as well as the third and lateral ventricles. However, an overall modest DA (73.4%) was observed for the individual discrimination between first-episode schizophrenia patients and controls, and the classifier failed to predict 1-year prognosis (remitting versus non-remitting course) of first-episode schizophrenia (DA=58.3%). In conclusion, using a "real world" sample recruited with epidemiological methods, the application of a neuroanatomical pattern classifier afforded only modest DA to classify first-episode schizophrenia subjects and next-door healthy controls, and poor discriminative power to predict the 1-year prognosis of first-episode schizophrenia. PMID:23261522

Zanetti, Marcus V; Schaufelberger, Maristela S; Doshi, Jimit; Ou, Yangming; Ferreira, Luiz K; Menezes, Paulo R; Scazufca, Marcia; Davatzikos, Christos; Busatto, Geraldo F

2013-06-01

206

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

207

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

2013-05-01

208

Hediger revisited: how do zoo animals see us?  

PubMed

Contact with people, both familiar (e.g., caretakers) and unfamiliar (e.g., members of the public), is a significant part of the lives of nonhuman animals in zoos. The available empirical evidence shows that in many cases this contact represents a source of stress to the animals, although there is sufficient overall ambiguity in these studies to suggest that the effect of people on the animals is much more complex than this. A possible way to try to understand human-animal relationships in the zoo is to ask how the animals might perceive the humans with whom they have contact, and here this question is explored further, using a framework first published by Hediger as a starting point. Hediger suggested that zoo animals might perceive people as an enemy, as part of the inanimate environment, or as a member of the same species. He supported these categories with anecdotal evidence, which was all that was available at the time, but more empirical evidence is available now, so it is appropriate to revisit these categories. The evidence suggests that animals discriminate both conspecific and heterospecific others, rather than just viewing familiar people as members of their own species, and that additional categories (stimulating part of the environment and friendship) may be warranted. These categories are then placed in a general model that suggests how relationships of different qualities, and hence different perceptions of each other, might develop between animals and the people they are in contact with in zoos. PMID:24079488

Hosey, Geoff

2013-01-01

209

How to infer gene networks from expression profiles, revisited  

PubMed Central

Inferring the topology of a gene-regulatory network (GRN) from genome-scale time-series measurements of transcriptional change has proved useful for disentangling complex biological processes. To address the challenges associated with this inference, a number of competing approaches have previously been used, including examples from information theory, Bayesian and dynamic Bayesian networks (DBNs), and ordinary differential equation (ODE) or stochastic differential equation. The performance of these competing approaches have previously been assessed using a variety of in silico and in vivo datasets. Here, we revisit this work by assessing the performance of more recent network inference algorithms, including a novel non-parametric learning approach based upon nonlinear dynamical systems. For larger GRNs, containing hundreds of genes, these non-parametric approaches more accurately infer network structures than do traditional approaches, but at significant computational cost. For smaller systems, DBNs are competitive with the non-parametric approaches with respect to computational time and accuracy, and both of these approaches appear to be more accurate than Granger causality-based methods and those using simple ODEs models.

Penfold, Christopher A.; Wild, David L.

2011-01-01

210

Revisiting cosmic no-hair theorem for inflationary settings  

NASA Astrophysics Data System (ADS)

In this work we revisit Wald’s cosmic no-hair theorem [R. M. Wald, Phys. Rev. DPRVDAQ0556-2821 28, 2118 (1983).10.1103/PhysRevD.28.2118] in the context of accelerating Bianchi cosmologies for a generic cosmic fluid with nonvanishing anisotropic stress tensor and when the fluid energy-momentum tensor is of the form of a cosmological constant term plus a piece which does not respect strong or dominant energy conditions. Such a fluid is the one appearing in inflationary models. We show that for such a system anisotropy may grow, in contrast to the cosmic no-hair conjecture. In particular, for a generic inflationary model we show that there is an upper bound on the growth of anisotropy. For slow-roll inflationary models, our analysis can be refined further and the upper bound is found to be of the order of slow-roll parameters. We examine our general discussions and our extension of Wald’s theorem for three classes of slow-roll inflationary models, generic multiscalar field driven models, anisotropic models involving U(1) gauge fields and the gauge-flation scenario.

Maleknejad, A.; Sheikh-Jabbari, M. M.

2012-06-01

211

Advanced Single-Aisle Transport Propulsion Design Options Revisited  

NASA Technical Reports Server (NTRS)

Future propulsion options for advanced single-aisle transports have been investigated in a number of previous studies by the authors. These studies have examined the system level characteristics of aircraft incorporating ultra-high bypass ratio (UHB) turbofans (direct drive and geared) and open rotor engines. During the course of these prior studies, a number of potential refinements and enhancements to the analysis methodology and assumptions were identified. This paper revisits a previously conducted UHB turbofan fan pressure ratio trade study using updated analysis methodology and assumptions. The changes incorporated have decreased the optimum fan pressure ratio for minimum fuel consumption and reduced the engine design trade-offs between minimizing noise and minimizing fuel consumption. Nacelle drag and engine weight are found to be key drivers in determining the optimum fan pressure ratio from a fuel efficiency perspective. The revised noise analysis results in the study aircraft being 2 to 4 EPNdB (cumulative) quieter due to a variety of reasons explained in the paper. With equal core technology assumed, the geared engine architecture is found to be as good as or better than the direct drive architecture for most parameters investigated. However, the engine ultimately selected for a future advanced single-aisle aircraft will depend on factors beyond those considered here.

Guynn, Mark D.; Berton, Jeffrey J.; Tong, Michael T.; Haller, William J.

2013-01-01

212

Oxytocin revisited: It is also a cardiovascular hormone.  

PubMed

Oxytocin (OT), traditionally associated with reproductive functions, was revisited recently, which revealed several new functions of the hormone in cardiovascular regulation. To support this contention, we have demonstrated the presence and synthesis of OT receptors in all heart compartments and the vasculature. The functionality of these receptors has been established by the ability of OT to induce atrial natriuretic peptide and nitric oxide (NO) release from the perfused heart and atrial slices. OT's cardiovascular actions include natriuresis, blood pressure reduction, negative inotropic and chronotropic effects, parasympathetic neuromodulation, as well as vasodilatation triggered by the NO pathway that is also involved in endothelial cell growth and anti-inflammatory activity. In addition, we have reported the abundance of the OT system in the early developing heart and OT's capacity to generate cardiomyocytes from mouse embryonic stem cells. The most potent inducer of cardiac differentiation, OT-Gly-Lys-Arg, is an extended form of OT that is abundantly expressed in the fetal heart. Therefore, in pathological conditions, OT plays an anti-inflammatory and cardioprotective role, improving vascular and metabolic functions; it has potential for therapeutic use. PMID:20409913

Gutkowska, Jolanta; Jankowski, Marek

2008-01-01

213

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

214

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

215

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

216

Revisiting the quantum Szilard engine with fully quantum considerations  

SciTech Connect

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{yields}{infinity} or the temperature of the bath T{yields}{infinity} the QSZE reduces to the classical Szilard engine (CSZE), and the total work satisfies the relation W{sub tot}=k{sub B}Tln2 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. - Highlights: Black-Right-Pointing-Pointer For the first time analyze the QSZE by considering energy level shifts. Black-Right-Pointing-Pointer Find different roles played by classical and quantum information in the QSZE. Black-Right-Pointing-Pointer The amount of work extracted depends on the cyclic strategies of the QSZE. Black-Right-Pointing-Pointer Verify that the QSZE will reduce to the CSZE in the classical limits.

Li, Hai [School of Physics, Beijing Institute of Technology, Beijing 100081 (China) [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); School of Information and Electronics Engineering, Shandong Institute of Business and Technology, Yantai 264000 (China); Zou, Jian, E-mail: zoujian@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)] [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Li, Jun-Gang; Shao, Bin [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)] [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Wu, Lian-Ao [Department of Theoretical Physics and History of Science, The Basque Country University (EHU/UPV), P.O. Box 644, ES-48080 Bilbao (Spain) [Department of Theoretical Physics and History of Science, The Basque Country University (EHU/UPV), P.O. Box 644, ES-48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, ES-48011 Bilbao (Spain)

2012-12-15

217

Revisiting the Monoamine Hypothesis of Depression: A New Perspective  

PubMed Central

As the incidence of depression increases, depression continues to inflict additional suffering to individuals and societies and better therapies are needed. Based on magnetic resonance spectroscopy and laboratory findings, gamma aminobutyric acid (GABA) may be intimately involved in the pathophysiology of depression. The isoelectric point of GABA (pI = 7.3) closely approximates the pH of cerebral spinal fluid (CSF). This may not be a trivial observation as it may explain preliminary spectrophotometric, enzymatic, and HPLC data that monoamine oxidase (MAO) deaminates GABA. Although MAO is known to deaminate substrates such as catecholamines, indoleamines, and long chain aliphatic amines all of which contain a lipophilic moiety, there is very good evidence to predict that a low concentration of a very lipophilic microspecies of GABA is present when GABA pI = pH as in the CSF. Inhibiting deamination of this microspecies of GABA could explain the well-established successful treatment of refractory depression with MAO inhibitors (MAOI) when other antidepressants that target exclusively levels of monoamines fail. If further experimental work can confirm these preliminary findings, physicians may consider revisiting the use of MAOI for the treatment of non-intractable depression because the potential benefits of increasing GABA as well as the monoamines may outweigh the risks associated with MAOI therapy.

Goldberg, Joel S; Bell, Clifton E; Pollard, David A

2014-01-01

218

NLTE in a Hot Hydrogen Star: Auer & Mihalas Revisited  

NASA Astrophysics Data System (ADS)

We pay tribute to two landmark papers published by Auer & Mihalas in 1969. They modeled hot-star NLTE-RE hydrogen-only atmospheres, using two simplified hydrogen atoms: ApJ 156, 157: H I levels 1, 2 and c, Lyman ? the only line ApJ 156, 681: H I levels 1, 2, 3 and c, Balmer ? the only line and computed LTE and NLTE models with the single line turned on and off. The results were extensively analyzed in the two papers. Any student of stellar line formation should take these beautiful papers to heart. The final exercise in Rutten's lecture notes ``Radiative Transfer in Stellar Atmospheres'' asks the student to work through five pages of questions concerning diagrams from the first paper alone! That exercise led to the present work in which we recompute the Auer-Mihalas hot-hydrogen-star models with TLUSTY, adding results from a complete hydrogen atom for comparison. Our motivation for this Auer-Mihalas re-visitation is twofold: 1. to add diagnostic diagrams to the ones published by Auer & Mihalas, in particular B?, J?, S? graphs to illustrate the role of the radiation field, and radiative heating & cooling graphs to illustrate the radiative energy budget, 2. to see the effect of adding the rest of the hydrogen atom.

Wiersma, J.; Rutten, R. J.; Lanz, T.

2003-01-01

219

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

220

Maturation of the human medial efferent reflex revisited  

PubMed Central

Past work applying otoacoustic emissions to gauge maturational status of the medial olivocochlear (MOC) reflex in human newborns has produced mixed results. The present study revisits the question while considering the dual nature of the 2f1 – f2 distortion product otoacoustic emission (DPOAE) and expanding measures of medial efferent function. Subjects included premature and term-born neonates, 6-month-old infants and young adults. The MOC reflex was elicited with contralateral acoustic stimulation (CAS) while shifts in amplitude and phase of the DPOAE, and its distortion and reflection components, were monitored. Overall, CAS-elicited reductions in DPOAE level did not differ among age groups. For all ages, the MOC reflex was strongest at frequencies below 1.5 kHz, and the reflection component of the DPOAE was most affected, showing maximally reduced amplitude and shallower phase slope when contralateral noise was presented. Results suggest that the MOC reflex likely reaches maturation prior to full-term birth. However, prematurely born neonates show markedly more episodes of CAS-induced DPOAE level enhancement. This may be due to more intrusive component mixing in this age group or disruptions in the formation of the MOC pathway or synapse in the most premature neonates.

Abdala, Carolina; Mishra, Srikanta; Garinis, Angela

2013-01-01

221

Lunar eclipse theory revisited: Scattered sunlight in both the quiescent and the volcanically perturbed atmosphere  

Microsoft Academic Search

The residual brightness of the shadowed Moon during a lunar eclipse is attributed to unscattered sunlight rays refracted in the Earth's atmosphere. The classical theory of lunar eclipses is built on the premise that the sunlight scattered by the gases and particles in the atmosphere contributes negligibly to the brightness of the eclipsed Moon. The current work revisits the lunar

A. García Muñoz; E. Pallé

2011-01-01

222

The Toolbox Revisited: Paths to Degree Completion From High School Through College  

ERIC Educational Resources Information Center

The Toolbox Revisited is a data essay that follows a nationally representative cohort of students from high school into postsecondary education, and asks what aspects of their formal schooling contribute to completing a bachelor's degree by their mid-20s. The universe of students is confined to those who attended a four-year college at any time,…

Adelman, Clifford

2006-01-01

223

Revisiting "Grutter" and "Gratz" in the Wake of "Fisher": Looking Back to Move Forward  

ERIC Educational Resources Information Center

This article revisits the University of Michigan's 2003 affirmative action cases, "Grutter v. Bollinger" and "Gratz v. Bollinger." Through the aid of critical textual analysis and critical race theory, the author looks back at the predominant narratives that framed the challenge to, and defense of, race-conscious affirmative action policy in the…

Ledesma, Maria C.

2013-01-01

224

Measuring the Effectiveness of Schooling Policies in Developing Countries: Revisiting Issues of Methodology.  

ERIC Educational Resources Information Center

Revisits key school effectiveness measurement issues: difficulties in evaluating school effectiveness from behavioral data due to observation/measurement problems; evidence on marginal values of schooling outputs and schooling production relations; methodological issues in underlying studies and their carryover to cost-benefit estimates; and…

Behrman, Jere R.

1996-01-01

225

Framing the Future: Revisiting the Place of Educational Expectations in Status Attainment  

ERIC Educational Resources Information Center

This study revisits the Wisconsin model of status attainment from a life course developmental perspective. Fixed-effects regression analyses lend strong support to the Wisconsin framework's core proposition that academic performance and significant others' influence shape educational expectations. However, investigating the process of expectation…

Bozick, Robert; Alexander, Karl; Entwisle, Doris; Dauber, Susan; Kerr, Kerri

2010-01-01

226

Where Are They Now? LJ Revisits a Decade's Worth of Graduates  

ERIC Educational Resources Information Center

In this article, the author revisits 11 graduates who were profiled as part of LJ's annual Placements & Salaries issue. Armed with a library science degree from various institutions, they had just secured jobs in librarianship and were off to a good start forging their careers. Since then, they have worked at elementary school, college, and…

Kuzyk, Raya

2006-01-01

227

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

228

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

229

The three-dimensional instability of a strained vortex tube revisited  

Microsoft Academic Search

We revisit the Moore Saffman Tsai Widnall instability, a parametric resonance between left- and right-handed bending waves of infinitesimal amplitude, on the Rankine vortex strained by a weak pure shear flow. The results of Tsai & Widnall (1976) and Eloy & Le Dizès (2001), as generalized to all pairs of Kelvin waves whose azimuthal wavenumbers m are separated by 2,

Yasuhide Fukumoto

2003-01-01

230

The role of variety seeking in short and long run revisit intentions in holiday destinations  

Microsoft Academic Search

Purpose – The main purpose of the present paper is to identify the differences in the antecedents of holiday destinations revisit intentions in the short and long run. Specifically, this work analyzes the influence of specific variety seeking, perceived value, destination image, satisfaction, switching costs and past switching behavior. Design\\/methodology\\/approach – This is a quantitative study and the authors collected

J. Enrique Bigné; Isabel Sánchez; Luisa Andreu

2009-01-01

231

Concluding Messages: The Toolbox Revisited--Paths to Degree Completion from High School through College  

ERIC Educational Resources Information Center

Compared to its predecessor, "Answers in the Tool Box," the preponderance of the "Toolbox Revisited" story has been on the postsecondary side of the matriculation line. Implicitly, it calls on colleges, universities, and community colleges to be a great deal more interventionary in the precollegiate world, to be more self-reflective about the…

Adelman, Clifford

2005-01-01

232

The Twin Paradox Revisited and Reformulated -- On the Possibility of Detecting Absolute Motion  

Microsoft Academic Search

The famous twin paradox of the Special Theory of Relativity by Einstein (1905) is revisited and revised. This paradox is not a paradox in the true sense of a paradox but a reflection of a misunderstanding of the problem and the Principle of Relativity. The currently accepted solution to this takes into account the accelerations and deceleration of the traveling

G. G. Nyambuya; M. D. Ngobeni

2008-01-01

233

Structuralism's Relevance in a Post-Structural Era: Re-Visiting Research on Multicultural Curricular Studies  

ERIC Educational Resources Information Center

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…

Shim, Jenna Min

2011-01-01

234

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

235

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

236

Atmospheric Entry Heating of Micrometeorites Revisited: Higher Temperatures and Potential Biases  

NASA Technical Reports Server (NTRS)

The atmospheric entry heating model of Love and Brownlee appears to have overestimated evaporation rates by as much as two orders of magnitude. Here we revisit the issue of atmospheric entry heating, using a revised prescription for evaporation rates. Additional information is contained in the original extended abstract.

Love, S.; Alexander, C. M. OD.

2001-01-01

237

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

238

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 those…

Alim, H. Samy

2005-01-01

239

A REVISIT OF A CLASSIC PAPER ON AMPHIBIAN AND REPTILE COMMUNITY ECOLOGY  

Microsoft Academic Search

We reissue a key paper from the book Herpetological Communities edited by Norman Scott, Jr. This effort remains among the most cited herpetological titles in community ecology. This revisit reminds us that the status of community ecology research continues to be in its infancy and much remains for us to investigate. Further, it contains many probing questions on how to

R. BRUCE BURY; MALCOLM L. MCCALLUM; RAYMOND A. SAUMURE; DAVID J. GERMANO; STANLEY E. TRAUTH

240

Revisiting the Age-Old Question: Does Money Matter in Education?  

ERIC Educational Resources Information Center

This policy brief revisits the long and storied literature on whether money matters in providing a quality education. Increasingly, political rhetoric adheres to the unfounded certainty that money doesn't make a difference in education, and that reduced funding is unlikely to harm educational quality. Such proclamations have even been used to…

Baker, Bruce D.

2012-01-01

241

Asian Lifelong Learning in the Context of a Global Knowledge Economy: A Task Re-Visited  

ERIC Educational Resources Information Center

This article revisits and reinterprets my previous paper. It is a snapshot of the lifelong learning system building in selected Asian countries, reflected in the mirror of the Asian Financial Crisis in the 1997s and the aftermath of that event. I reconsidered the arguments (1) the economic recession had delivered a global dimension of lifelong…

Han, Soonghee

2007-01-01

242

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

243

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

244

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

245

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

246

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

247

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

248

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 performance and the level of environmental disclosures. We revisit this relation by testing competing predictions from economics 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 by developing

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

2008-01-01

249

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

250

Revisiting the doping requirement for low power junctionless MOSFETs  

NASA Astrophysics Data System (ADS)

In this work, we revisit the requirement of higher channel doping (?1019 cm?3) in junctionless (JL) double gate MOSFETs. It is demonstrated that moderately doped (1018 cm?3) ultra low power (ULP) JL transistors perform significantly better than heavily doped (1019 cm?3) devices. JL MOSFETs with moderate doping results in the spreading out of carriers across the entire silicon film instead of being localized at the center of the film. This improves gate controllability leading to higher on–off current ratio and lower intrinsic delay for ULP subthreshold logic applications. Additional benefits of using a channel doping concentration of 1018 cm?3 instead of conventional heavily doped design is the significant reduction in threshold voltage sensitivity values (by ?70–90%) with respect to film thickness and gate oxide thickness. Further improvement in ULP performance metrics can be achieved by limiting the source/drain implantation away from the gate edge. This design, specifically for ULP, allows the requirement of gate workfunction to be reduced from p+-poly (? 5.1 eV) to near about midgap values (? 4.8 eV). On–off current ratio and intrinsic delay for optimized JL devices are compared for low standby power projections of the technological roadmap. A 6T-SRAM cell operating at 0.8 V with 25 nm JL devices exhibits a static noise margin of 151 mV with gate workfunction offset of 0.2 eV with respect to midgap value (4.72 eV). The results highlight new viewpoints for realizing improved low power JL transistors.

Singh Parihar, Mukta; Kranti, Abhinav

2014-07-01

251

Inhibition of Apurinic/apyrimidinic endonuclease I's redox activity revisited  

PubMed Central

The essential base excision repair protein, apurinic/apyrimidinic endonuclease 1 (APE1), plays an important role in redox regulation in cells and is currently targeted for development of cancer therapeutics. One compound that binds APE1 directly is (E)-3-(2-(5,6-dimethoxy-3-methyl-1,4-benzoquinonyl))-2-nonyl propenoic acid (E3330). Here, we revisit the mechanism by which this negatively charged compound interacts with APE1 and inhibits its redox activity. At high concentrations (mM), E3330 interacts with two regions in the endonuclease active site of APE1, as mapped by hydrogen/deuterium exchange mass spectrometry. However, this interaction lowers the melting temperature of APE1 consistent with a loss of structure in APE1, as measured by both differential scanning fluorimetry and circular dichroism. These results are consistent with other findings that concentrations of E3330 greater than 100 ?M are required to inhibit APE1’s endonuclease activity. To determine the role of E3330’s negatively charged carboxylate in redox inhibition, we converted the carboxylate to an amide by synthesizing (E)-2-((4,5-dimethoxy-2-methyl-3,6-dioxocyclohexa-1,4-dien-1-yl)methylene)-N-methoxy-undecanamide (E3330-amide), a novel uncharged derivative. E3330-amide has no effect on the melting temperature of APE1, suggesting that it does not interact with the fully-folded protein. However, E3330-amide inhibits APE1’s redox activity in in vitro EMSA redox and cell-based transactivation assays producing lower IC50 values as compared to E3330, 8.5 ?M vs. 20 ?M and 7 ?M vs. 55 ?M, respectively. Thus, E3330’s negatively charged carboxylate is not required for redox inhibition. Collectively, our results provide additional support for a mechanism of redox inhibition involving interaction of E3330 or E3330-amide with partially unfolded APE1.

Zhang, Jun; Luo, Meihua; Marasco, Daniela; Logsdon, Derek; LaFavers, Kaice A.; Chen, Qiujia; Reed, April; Kelley, Mark R.; Gross, Michael L.; Georgiadis, Millie M.

2013-01-01

252

South Asian summer monsoon: Role of Plateau heating revisited  

NASA Astrophysics Data System (ADS)

A recent GCM based study by William and Zhiming (nature, 2010) suggests that orographic insulation provided by the Himalayas and adjacent mountains predominantly controls South Asian monsoon, debating the previously recognized role of the Tibetan plateau as a dominant thermal forcing. However, at a typical GCM resolution, neither the Himalayas and the Plateau are distinguishable nor the topographic gradient is correctly represented. Therefore, it is imperative to test the reproducibility of these results with high-resolution nested climate models. Using the Weather Research and Forecasting Model (WRF), we revisit the role of Plateau heating versus the role of orographic insulation. Following the methodology used in the above-mentioned study, we perform cloud-resolving scale South Asian summer monsoon simulations with and without modifications in the topography. In addition, we perform similar WRF simulations at a resolution comparable to that of a GCM. In order for the orographic insulation to be the dominant factor in South Asian summer monsoon development, we expect to find 1) comparable results both at coarse and cloud-resolving scales with and without the availability of Plateau heating, and 2) insensitivity of reversal and strengthening of meridional tropospheric temperature gradient (MTG) to the presence of Plateau. In order to test that, we first compare coarse-scale and cloud-resolving scale WRF simulations to investigate the potential influence of realistic representation of South Asian topography on the simulation of summer monsoon. Second, we compare the differences between coarse-scale simulations with and without topographic modification to the differences between cloud-resolving scale simulations with and without topographic modifications, with a particular focus on the role of Plateau heating in MTG variations, and the importance of MTG in the development of South Asian summer monsoon.

Ashfaq, M.; Bisht, G.

2010-12-01

253

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

2007-09-01

254

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

255

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

256

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

257

Revisited Inventory of Glaciers on Axel Heiberg Island, Nunavut  

NASA Astrophysics Data System (ADS)

As documented in the IPCC's Climate Change 2007 report, the high latitude regions of the Northern Hemisphere are experiencing the highest rates of warming. Given that 35% of the global glacial ice exists within the Arctic Archipelago, this region provides an excellent laboratory for monitoring the anticipated degree of glacial recession [1]. Evidence of arctic warming through negative mass balance trends has been detected in several studies already [e.g., 2]. Here, we show the importance and value of historical records in the task of monitoring glacial retreat. A highly detailed inventory developed by S. Ommanney in 1969 [3], has been revisited and transformed into digital format for the purposes of integration with modern inventories. The Ommanney inventory covers the entirety of Axel Heiberg Island , NU, and includes details often lacking in present day inventories, including orientations (accumulation and ablation zones), elevations (highest, lowest, elevation of the snowline, and the mean elevations of both the accumulation and ablation areas), length (of the ablation area, exposed ice, and of the total glacier including debris cover), area (of the ablation area, exposed ice, and of the total glacier), accumulation area ratio (AAR), depth, volume, and a six digit code which gives qualitative details on glacier attributes. This report is one of the most thorough and comprehensive glacier inventory report ever published in Canada. More recent inventories used for comparison include the glacier extents created by the National Topographic System based on photography from 1980-1987, as well as extents developed by Dr. Luke Copland for the Global Land Ice Measurements from Space (GLIMS) database using 1999-2000 satellite imagery. Our preliminary results show that approximately 90% of ice bodies under 0.2km on Axel Heiberg Island have disappeared entirely in the 40 year period of interest. The issue of glacier definition will be discussed as a possible cause of these drastic changes in the status of small, remnant glaciers. Recession trends will also be discussed with respect to glacier characteristics and regional distribution. [1] Barry, R. G., Progress in Physical Geography, 2006. 30(3): p. 285-306; [2] Dowdeswell, J. A., et al., Quaternary Research, 1997. 40: p. 1-14; [3] Ommanney, C. S. L., McGill Subarctic Research Paper, 1969. 40: p. 5-67.

Thomson, L.; Osinski, G.

2009-05-01

258

The Angular Momentum of Baryons and Dark Matter Halos Revisited  

NASA Technical Reports Server (NTRS)

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 hydrodynamics simulations with adaptive-mesh refinement (AMR), we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r = 0.1R(sub vir). In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/R(sub vir) > 0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its virialised dark matter halo host. This generic result holds for halos of all masses at all redshifts, as radiative cooling ensures that a significant fraction of baryons remain trapped at the centre of the halos. Despite this injection of angular momentum enriched gas, we predict an amount for stellar discs which is in fair agreement with observations at z=0. This arises because the total specific angular momentum of the baryons (gas and stars) remains close to that of dark matter halos. Indeed, our simulations indicate that any differential loss of angular momentum amplitude between the two components is minor even though dark matter halos continuously lose between half and two-thirds of their specific angular momentum modulus as they evolve. In light of our results, a substantial revision of the standard theory of disc formation seems to be required. We propose a new scenario where gas efficiently carries the angular momentum generated by large-scale structure motions deep inside dark matter halos, redistributing it only in the vicinity of the disc.

Kimm, Taysun; Devriendt, Julien; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A.; Dubois, Yohan

2011-01-01

259

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

260

Moral judgment development across cultures: Revisiting Kohlberg’s universality claims  

Microsoft Academic Search

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. Psychological Bulletin, 97, 202–232] examined Kohlberg’s claims in a survey of 45 cross-cultural studies in 27 countries that used

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

2007-01-01

261

Tales of sociology and the nursing curriculum: revisiting the debates.  

PubMed

The relationship between nursing and sociology has been extensively debated for more than two decades [Cox, C.A., 1979. Who cares? Nursing and sociology: the development of a symbiotic relationship. Journal of Advanced Nursing 4, 237-252; Cooke, H., 1993. Why teach sociology? Nurse Education Today 13, (3) 210-216; Sharpe, K., 1994. Sociology and the nursing curriculum: a note of caution. Journal of Advanced Nursing 20, (2) 391-395; Sharpe, K., 1995. Why indeed should we teach sociology? A response to Hannah Cooke. Nurse Education Today 15, (1) 52-55; Sharpe, K., 1996. Feedback - sociology and the nursing curriculum: a reply to Sam Porter. Journal of Advanced Nursing 23, (7) 1275-1278; Balsamo, D., Martin, S.I., 1995a. Developing the sociology of health in nurse education: towards a more critical curriculum. Part 1. Andragogy and sociology in Project 2000. Nurse Education Today 15, 427-432; Balsamo, D., Martin, S.I., 1995b. Developing the sociology of health in nurse education: towards a more critical curriculum. Part 2. Linking methodology and epistemology. Nurse Education Today 15, 427-432; Porter, S., 1995. Sociology and the nursing curriculum: a defence. Journal of Advanced Nursing 21, (6) 1130-1135; Porter, S., 1996. Why teach sociology? A contribution to the debate. Nurse Education Today, 16, 170-174; Porter, S., 1997. Sociology and the nursing curriculum: a further comment. Journal of Advanced Nursing 26, (1) 214-218; Porter, S., 1998. Social Theory and Nursing Practice. Macmillan, Basingstoke; Corlett, J., 2000. The perceptions of nurse teacher, student nurses and preceptors of the theory-practice gap in nurse education. Nurse Education Today 20, 499-505; Allen, D., 2001. Review article: nursing and sociology: an uneasy marriage?. Sociology of Health and Illness 23, (3) 386-396; Pinikahana, J., 2003. Role of sociology within the nursing enterprise: some reflections on the unfinished debate. Nursing and health Sciences 5, (2) 175-180; Holland, K., 2004. Sociology and the nursing curriculum; editorial. Nurse Education in Practice 4, 81-82; Mowforth, G., Harrison, J., Morris, M., 2005. An investigation into adult nursing students' experience of the relevance and application of behavioural sciences (biology, psychology and sociology) across two different curricula. Nurse Education Today 25, 41-48]. Much attention has been given to the role, utility and value of sociology mostly within pre-registration but also post-registration nursing curricula. Through an initial analysis of a series of letters appearing in The Nursing Times over a 12 week period in 2004, and using an analytical framework of four tales (realist, critical, deconstructive and reflexive) we revisit this relationship. Unlike previous debates our argument is that this relationship is more usefully viewed as emblematic of the legitimation crisis inherent in all modern projects. We argue that in order to move beyond the 'utility' discussion, an interrogation of the knowledge claims of both nursing and sociology is required. PMID:17064822

Aranda, Kay; Law, Kate

2007-08-01

262

Associations between in-hospital bed occupancy and unplanned 72-h revisits to the emergency department: a register study  

PubMed Central

Background A possible downstream effect of high in-hospital bed occupancy is that patients in the emergency department (ED) who would benefit from in-hospital care are denied admission. The present study aimed at evaluating this hypothesis through investigating associations between in-hospital bed occupancy at the time of presentation in the ED and the probability for unplanned 72-hour (72-h) revisits to the ED among patients discharged at index. A second outcome was unplanned 72-h revisits resulting in admission. Methods All visits to the ED of a 420-bed emergency hospital in southern Sweden between 1 January 2011 and 31 December 2012, which did not result in admission, death, or transfer to another hospital were included. Revisiting fractions were computed for in-hospital occupancy intervals <85%, 85% to 90%, 90% to 95%, 95% to 100%, 100% to 105%, and ?105%. Multivariate models were constructed in an attempt to take confounding factors from, e.g., presenting complaints, age, referral status, and triage priority into account. Results Included in the study are 81,878 visits. The fraction of unplanned 72-h revisits/unplanned 72-h revisits resulting in admission was 5.8%/1.4% overall, 6.2%/1.4% for occupancy <85%, 6.4%/1.5% for occupancy 85% to 90%, 5.8%/1.4% for occupancy 90% to 95%, 6.0%/1.6% for occupancy 95% to 100%, 5.4%/1.6% for occupancy 100% to 105%, and 4.9%/1.4% for occupancy ?105%. In the multivariate models, a trend to lower probability of unplanned 72-h revisits was observed at occupancy ?105% compared to occupancy <95% (OR 0.88, CI 0.76 to 1.01). No significant associations between in-hospital occupancy at index and the probability of making unplanned 72-h revisits resulting in admission were observed. Conclusions The lack of associations between in-hospital occupancy and unplanned 72-h revisits does not support the hypothesis that ED patients are inappropriately discharged when in-hospital beds are scarce. The results are reassuring as they indicate that physicians are able to make good decisions, also while resources are constrained.

2014-01-01

263

Effective properties and band structures of lamellar subwavelength crystals: Plane-wave method revisited  

NASA Astrophysics Data System (ADS)

The plane-wave method used to compute the band structure of photonic crystals is revisited in light of recent mathematical results about the Fourier factorization of products of discontinuous functions. Highly accurate numerical predictions for the effective index and for the band structure are obtained for two- and three-dimensional dielectric lamellar crystals with high dielectric contrasts. At the same time, we clarify some aspects related to the effective properties of multidimensional crystals by establishing clear links between their band structures and their effective indices.

Lalanne, Philippe

1998-10-01

264

Psychosis as a Disorder of Reduced Cathectic Capacity: Freud's Analysis of the Schreber Case Revisited  

PubMed Central

Approximately 100 years ago, a prominent German public figure name Daniel Schreber wrote memoirs of his experiences in asylums. His case was diagnosed Dementia Praecox at times and Paranoia at others by his treaters. Freud analyzed Schreber's memoirs from the perspective of his “libido” theory of developmentally organized mental “cathexes” or ideational/emotional investments in self and others. Revisiting Freud's analysis of the Schreber case suggests that it may represent the first theoretical articulation that the pathophysiologic core of psychosis is one of deficit, i.e., of diminished (organic) cathectic capacity for normal mental and affective investments in life.

McGlashan, Thomas H.

2009-01-01

265

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

266

Stefan-Boltzmann law for the tungsten filament of a light bulb: Revisiting the experiment  

NASA Astrophysics Data System (ADS)

A classical laboratory experiment to verify the Stefan-Boltzmann radiation law with the tungsten filaments of commercial incandescent lamps has been fully revisited, collecting a fairly large amount of data with a computer-controlled four-channel power supply. In many cases, the total power dissipated by the lamp is well described by a sum of two power-law terms, with one exponent very close to 4, as predicted by the radiation law, and the other very close to 1, as for simple heat conduction. This result was true even for filament surfaces with a shiny metallic appearance, whose emissivity should vary with temperature.

Carlà, Marcello

2013-07-01

267

LETTERS AND COMMENTS: Reply to Comment by J Roche on `Maxwell's displacement current revisited'  

NASA Astrophysics Data System (ADS)

I reply to a Comment by J Roche (2000 Eur. J. Phys. 21 L27-8) on my paper `Maxwell's displacement current revisited' (1999 Eur. J. Phys. 20 495-9), which contrasted commonly accepted views with those expressed by Roche in his earlier paper `The present status of Maxwell's displacement current' (1998 Eur. J. Phys. 19 155-66).

Jackson, J. D.

2000-07-01

268

Long, cold, early r process? Neutrino-induced nucleosynthesis in He shells revisited.  

PubMed

We revisit a ?-driven r-process mechanism in the He shell of a core-collapse supernova, finding that it could succeed in early stars of metallicity Z ? 10?³ Z(?), at relatively low temperatures and neutron densities, producing A ~ 130 and 195 abundance peaks over ~10-20 s. The mechanism is sensitive to the ? emission model and to ? oscillations. We discuss the implications of an r process that could alter interpretations of abundance data from metal-poor stars, and point out the need for further calculations that include effects of the supernova shock. PMID:21668217

Banerjee, Projjwal; Haxton, W C; Qian, Yong-Zhong

2011-05-20

269

Conservation laws for steady flow and solitons in a multifluid plasma revisited  

NASA Astrophysics Data System (ADS)

The conservation laws used in constructing the governing equations for planar solitons in multifluid plasmas are revisited. In particular, the concept of generalized vorticity facilitates the derivation of some general ``Bernoulli theorems,'' which reduce, in specific instances, to conservation laws previously deduced by other means. These theorems clarify the underlying physical principles that give rise to the conserved quantities. As an example of the usefulness of the techniques, even for relatively simple flows and progressive waves, the equations governing stationary nonlinear whistler waves propagating parallel to an ambient magnetic field are derived using generalized vorticity concepts.

Mace, R. L.; McKenzie, J. F.; Webb, G. M.

2007-01-01

270

Revisiting symmetry breaking in BNB: The key role of electronic correlation  

NASA Astrophysics Data System (ADS)

Spontaneous symmetry breaking in the ground state of the BNB molecule is revisited by employing a series of high-level multireference methods based on updated SA-CASSCF wavefunctions with larger active space. It supports our previous determination of two equivalent linear-noncentrosymmetric equilibrium configurations. The calculated magnitude of the barrier between them increases with the level of electronic correlation taken into account. The inadequate centrosymmetric structure obtained by MRCI calculations is caused by insufficient account of electronic correlation. The origin of the off-center distortion in BNB, as in many other systems, is due to the Pseudo Jahn-Teller effect.

Liu, Yang; Zou, Wenli; Bersuker, Isaac B.

2014-05-01

271

Long, Cold, Early r Process? Neutrino-Induced Nucleosynthesis in He Shells Revisited  

NASA Astrophysics Data System (ADS)

We revisit a ?-driven r-process mechanism in the He shell of a core-collapse supernova, finding that it could succeed in early stars of metallicity Z?10-3Z?, at relatively low temperatures and neutron densities, producing ˜130 and 195 abundance peaks over ˜10-20s. The mechanism is sensitive to the ? emission model and to ? oscillations. We discuss the implications of an r process that could alter interpretations of abundance data from metal-poor stars, and point out the need for further calculations that include effects of the supernova shock.

Banerjee, Projjwal; Haxton, W. C.; Qian, Yong-Zhong

2011-05-01

272

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

273

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

Microsoft Academic Search

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 community

Jacqueline Haydeni

274

Revisiting "Kindergarten as Academic Boot Camp": A Nationwide Study of Ability Grouping and Psycho-Social Development  

ERIC Educational Resources Information Center

We revisit Harry L. Gracey's perspective of kindergarten as academic boot camp where, at school entry, children acquire the student role through a structured program of activities. We provide further insights into the crucial mechanisms of socialization that occur in U.S. kindergartens by examining the relationship between within-class ability…

Catsambis, Sophia; Buttaro, Anthony, Jr.

2012-01-01

275

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

276

An analytic algorithm for global coverage of the revisiting orbit and its application to the CFOSAT satellite  

NASA Astrophysics Data System (ADS)

This paper addresses a new analytic algorithm for global coverage of the revisiting orbit and its application to the mission revisiting the Earth within long periods of time, such as Chinese-French Oceanic Satellite (abbr., CFOSAT). In the first, it is presented that the traditional design methodology of the revisiting orbit for some imaging satellites only on the single (ascending or descending) pass, and the repeating orbit is employed to perform the global coverage within short periods of time. However, the selection of the repeating orbit is essentially to yield the suboptimum from the rare measure of rational numbers of passes per day, which will lose lots of available revisiting orbits. Thus, an innovative design scheme is proposed to check both rational and irrational passes per day to acquire the relationship between the coverage percentage and the altitude. To improve the traditional imaging only on the single pass, the proposed algorithm is mapping every pass into its ascending and descending nodes on the specified latitude circle, and then is accumulating the projected width on the circle by the field of view of the satellite. The ergodic geometry of coverage percentage produced from the algorithm is affecting the final scheme, such as the optimal one owning the largest percentage, and the balance one possessing the less gradient in its vicinity, and is guiding to heuristic design for the station-keeping control strategies. The application of CFOSAT validates the feasibility of the algorithm.

Xu, Ming; Huang, Li

2014-04-01

277

Revisiting Down syndrome from the ENT perspective: review of literature and recommendations.  

PubMed

Down syndrome is the most common chromosomal abnormality among live born infants reaching up to 1 in 700 births and is characterized by a variety of dysmorphic features and medical conditions. The potential to reach their full developmental capacities can be hindered by ear, nose, and throat problems. Hence, knowledge of the various anatomic peculiarities that predispose them to various medical conditions is fundamental. The medical states resulting from these variations and suggested treatment options are reviewed. Such conditions include refractory otitis, eustachian tube dysfunction, laryngomalacia, tracheal stenosis, obstructive sleep apnea, hearing loss, and voice and articulatory impairments. This review revisits besides the otolaryngeal pathologies, special medical considerations in Down's syndrome patients that might affect surgical outcomes used in the management of the above pathologies. PMID:23689804

Ramia, Maria; Musharrafieh, Umayya; Khaddage, Wajdi; Sabri, Alain

2014-05-01

278

Signet ring stromal cell tumor revisited and related signet ring cell lesions of the ovary.  

PubMed

In this article, we revisit the first reported case of ovarian signet ring stromal cell tumor (SRSCT) using modern immunohistochemical techniques and compare it to a case of signet ring cell transformation of lutein cells in an ovarian stromal tumor having components of luteinized thecoma and sclerosing stromal tumor. We introduce a new classification of signet ring stromal cell lesions of the ovary that serves as a framework to distinguish pathogenetically distinct ovarian stromal lesions that may be confused with cases of true SRSCT. The SRSCT in our first case most likely arose directly from the ovarian stroma without an identifiable precursor neoplasm. In our second case, the association of the signet ring cells with lutein cells and the positive staining of the signet ring cells for inhibin and steroidogenic factor 1 confirm that in some instances signet ring cells are derived from lutein cells. PMID:24342431

Roth, Lawrence M; Ramzy, Ibrahim

2014-03-01

279

Revisit laser scanning fluorescence microscopy performance under fluorescence-lifetime-limited regime  

NASA Astrophysics Data System (ADS)

Continuing desire for higher-speed laser scanning fluorescence microscopy (LSFM) and progressive advancement in ultrafast and sensitive photodetectors might imply that our conventional understanding of LSFM is not adequate when approaching to the intrinsic speed limit — fluorescence lifetime. In this regard, we here revisit the theoretical framework of LSFM and evaluate its general performance in lifetime-limited and noise-limited regimes. Our model suggests that there still exists an order-of-magnitude gap between the current LSFM speed and the intrinsic limit. An imaging frame rate of > 100 kHz could be viable with the emerging laser-scanning techniques using ultrafast wavelength-swept sources, or optical time-stretch.

Chan, Antony C.; Wong, Terence T. W.; Wong, Kenneth K. Y.; Lam, Edmund Y.; Tsia, Kevin K.

2014-03-01

280

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

2013-03-01

281

What drives health care expenditure?--Baumol's model of 'unbalanced growth' revisited.  

PubMed

The share of health care expenditure in GDP rises rapidly in virtually all OECD countries, causing increasing concern among politicians and the general public. Yet, economists have to date failed to reach an agreement on what the main determinants of this development are. This paper revisits Baumol's [Baumol, W.J., 1967. Macroeconomics of unbalanced growth: the anatomy of urban crisis. American Economic Review 57 (3), 415-426] model of 'unbalanced growth', showing that the latter offers a ready explanation for the observed inexorable rise in health care expenditure. The main implication of Baumol's model in this context is that health care expenditure is driven by wage increases in excess of productivity growth. This hypothesis is tested empirically using data from a panel of 19 OECD countries. Our tests yield robust evidence in favor of Baumol's theory. PMID:18164773

Hartwig, Jochen

2008-05-01

282

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

283

Two-fluid scenario for dark energy models in an FRW universe-revisited  

NASA Astrophysics Data System (ADS)

In this paper we study the evolution of the dark energy parameter within the scope of a spatially homogeneous and isotropic Friedmann-Robertson-Walker (FRW) model filled with barotropic fluid and dark energy by revisiting the recent results (Amirhashchi et al. in Chin. Phys. Lett. 28:039801, 2011a). To prevail the deterministic solution we select the scale factor a(t) = sqrt{tnet} which generates a time-dependent deceleration parameter (DP), representing a model which generates a transition of the universe from the early decelerating phase to the recent accelerating phase. We consider the two cases of an interacting and non-interacting two-fluid (barotropic and dark energy) scenario and obtained general results. The cosmic jerk parameter in our derived model is also found to be in good agreement with the recent data of astrophysical observations under the suitable condition. The physical aspects of the models and the stability of the corresponding solutions are also discussed.

Saha, Bijan; Amirhashchi, Hassan; Pradhan, Anirudh

2012-11-01

284

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

285

Coronal loop hydrodynamics. The solar flare observed on November 12, 1980 revisited: The UV line emission  

NASA Astrophysics Data System (ADS)

We revisit a well-studied solar flare whose X-ray emission originating from a simple loop structure was observed by most of the instruments on board SMM on November 12, 1980. The X-ray emission of this flare, as observed with the XRP, was successfully modeled previously. Here we include a detailed modeling of the transition region and we compare the hydrodynamic results with the UVSP observations in two EUV lines, measured in areas smaller than the XRP rasters, covering only some portions of the flaring loop (the top and the foot-points). The single loop hydrodynamic model, which fits well the evolution of coronal lines (those observed with the XRP and the Fe XXI 1354.1 Å line observed with the UVSP) fails to model the flux level and evolution of the O V 1371.3 Åline.

Betta, R. M.; Peres, G.; Reale, F.; Serio, S.

2001-12-01

286

Multiple drug resistance in cancer revisited: the cancer stem cell hypothesis.  

PubMed

The failure to eradicate cancer may be as fundamental as a misidentification of the target. Current therapies succeed at eliminating bulky disease but often miss a tumor reservoir that is the source of disease recurrence and metastasis. Recent advances in the understanding of tissue development and repair cause us to revisit the process of drug resistance as it applies to oncogenesis and tumor heterogeneity. The cancer stem cell hypothesis states that the cancer-initiating cell is a transformed tissue stem cell, which retains the essential property of self-protection through the activity of multiple drug resistance (MDR) transporters. This resting constitutively drug-resistant cell remains at low frequency among a heterogeneous tumor mass. In the context of this hypothesis, the authors review the discovery of MDR transporters in cancer and normal stem cells and the failure of MDR reversal agents to increase the therapeutic index of substrate antineoplastic agents. PMID:16027397

Donnenberg, Vera S; Donnenberg, Albert D

2005-08-01

287

Ortho/para ratio of H2O+ toward Sagittarius B2(M) revisited.  

PubMed

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. PMID:23713712

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

2013-10-01

288

Revisiting the symmetric reactions for synthesis of super-heavy nuclei of Z?120  

NASA Astrophysics Data System (ADS)

Extensive efforts have been made experimentally to reach nuclei in the super-heavy mass region of Z=110 and above with suitable choices of projectile and target nuclei. The cross sections for production of these nuclei are seen to be in the range of a few picobarn or less, and pose great experimental challenges. Theoretically, there have been extensive calculations for highly asymmetric (hot-fusion) and moderately asymmetric (cold-fusion) collisions and only a few theoretical studies are available for near-symmetric collisions to estimate the cross sections for production of super-heavy nuclei. In the present article, we revisit the symmetric heavy ion reactions with suitable combinations of projectile and target nuclei in the rare-earth region, that will lead to super-heavy nuclei of Z?120 with measurable fusion cross sections.

Choudhury, R. K.; Gupta, Y. K.

2014-04-01

289

Revisiting the Prominent Anti-Tumoral Potential of Pre-mNK Cells  

PubMed Central

Interferon-producing killer dendritic cells (IKDC) were first described for their outstanding anti-tumoral properties. The “IKDC” terminology implied the description of a novel DC subset and initiated a debate on their cellular lineage origin. This debate shifted the focus away from their notable anti-tumoral potential. IKDC were recently redefined as precursors to mature NK (mNK) cells and consequently renamed pre-mNK cells. Importantly, a putative human equivalent of pre-mNK cells was recently associated with improved disease outcome in cancer patients. It is thus timely to revisit the functional attributes as well as the therapeutic potential of pre-mNK cells in line with their newly defined NK-cell precursor function.

Guimont-Desrochers, Fanny; Lesage, Sylvie

2013-01-01

290

Polycarbonate crowns for primary teeth revisited: restorative options, technique and case reports.  

PubMed

Esthetics by definition is the science of beauty - that particular detail of an animate or inanimate object that makes it appealing to the eye. In the modern, civilized, and cosmetically conscious world, well-contoured and well-aligned white teeth set the standard for beauty. Such teeth are not only considered attractive but are also indicative of nutritional health, self esteem, hygienic pride, and economic status. Numerous treatment approaches have been proposed to address the esthetics and retention of restorations in primary teeth. Even though researchers have claimed that certain restorations are better than the others, particularly owing to the issues mentioned above, the search for the ideal esthetic restoration for the primary teeth continues. This paper revisits and attempts to reintroduce the full coverage restoration, namely, polycarbonate crown, for use in primary anterior teeth. PMID:24739917

Venkataraghavan, Karthik; Chan, John; Karthik, Sandhya

2014-01-01

291

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

292

Language planning for the 21st century: revisiting bilingual language policy for deaf children.  

PubMed

For over 25 years in some countries and more recently in others, bilingual education involving sign language and the written/spoken vernacular has been considered an essential educational intervention for deaf children. With the recent growth in universal newborn hearing screening and technological advances such as digital hearing aids and cochlear implants, however, more deaf children than ever before have the potential for acquiring spoken language. As a result, the question arises as to the role of sign language and bilingual education for deaf children, particularly those who are very young. On the basis of recent research and fully recognizing the historical sensitivity of this issue, we suggest that language planning and language policy should be revisited in an effort to ensure that they are appropriate for the increasingly diverse population of deaf children. PMID:22577073

Knoors, Harry; Marschark, Marc

2012-01-01

293

F center in lithium fluoride revisited: Comparison of solid-state physics and quantum-chemistry approaches  

NASA Astrophysics Data System (ADS)

We revisit the theoretical description of the F color center in lithium fluoride employing advanced complementary ab initio techniques. We compare the results from periodic supercell calculations involving density-functional theory (DFT) and post-DFT techniques with those from the embedded-cluster approach involving quantum-chemical many-electron wave-function techniques. These alternative approaches yield results in good agreement with each other and with the experimental data provided that correlation effects are properly taken into account.

Karsai, Ferenc; Tiwald, Paul; Laskowski, Robert; Tran, Fabien; Koller, David; Gräfe, Stefanie; Burgdörfer, Joachim; Wirtz, Ludger; Blaha, Peter

2014-03-01

294

Estimating the number of coding mutations in genotypic and phenotypic driven N -ethyl- N -nitrosourea (ENU) screens: revisited  

Microsoft Academic Search

We recently described methods for estimating the number of N-ethyl-N-nitrosourea (ENU)-induced coding mutations in phenotypic and genotypic screens. In this article we revisit these methods,\\u000a clarifying their application. In particular, we focus on the difference between unconditional and conditional probabilities.\\u000a We also introduce a website to assist investigators in the application of these equations (http:\\/\\/www.well.ox.ac.uk\\/enuMutRat).

David A. Keays; Taane G. Clark; Thomas G. Campbell; John Broxholme; William Valdar

2007-01-01

295

A Revisited Tsypkin Criterion for Discrete-Time Nonlinear Lur’e Systems with Monotonic Sector-Restrictions  

Microsoft Academic Search

This paper revisits a well-known Tsypkin criterion for stability analysis of discrete-time nonlinear Lur’e systems. When nonlinearities are monotonic and sector restricted by [0,??], where ?? is positive definite, it is shown by Kapila and Haddad that the system is absolutely stable if a function G0(z)=??-1+{I+(1?z-1)K+}G(z) is strictly positive real, where K+ is nonnegative diagonal and G(z) represents a transfer

SANG WOO KIM

1998-01-01

296

Revisit to Grad's Closure and Development of Physically Motivated Closure for Phenomenological High-Order Moment Model  

SciTech Connect

The Grad's closure for the high-order moment equation is revisited and, by extending his theory, a physically motivated closure is developed for the one-dimensional velocity shear gas flow. The closure is based on the physical argument of the relative importance of various terms appearing in the moment equation. Also, the closure is derived such that the resulting theory may be inclusive of the well established linear theory (Navier-Stokes-Fourier) as limiting case near local thermal equilibrium.

Myong, R. S.; Nagdewe, S. P. [Dept. of Mechanical and Aerospace Engineering and Research Center for Aircraft Parts Technology, Gyeongsang National University, Jinju, Gyeongnam 660-701 (Korea, Republic of)

2011-05-20

297

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

298

Capella revisited  

NASA Technical Reports Server (NTRS)

The highlights of two studies of Capella, a spectroscopic binary, undertaken during the third and fourth years of the IUE are given. The first program consists of high dispersion spectroscopy at critical phases of the Capella orbit. The second program is a two month monitoring effort to search for ultraviolet modulations induced by the rotation of magnetic active regions onto and off of the visible hemisphere of the Capella secondary.

Ayres, T. R.

1982-01-01

299

Revisiting Differentiation  

ERIC Educational Resources Information Center

With the passage of the "No Child Left Behind Act" (NCLB), the emphasis is for all children to reach proficient levels. Since they already work above this benchmark, the needs of gifted students are often de-emphasized. If teachers define learning as moving forward from the knowledge a student already has, they find that those who are at greatest…

Winebrenner, Susan

2007-01-01

300

Pseudodiagnosticity Revisited  

ERIC Educational Resources Information Center

In the psychology of reasoning and judgment, the pseudodiagnosticity task has been a major tool for the empirical investigation of people's ability to search for diagnostic information. A novel normative analysis of this experimental paradigm is presented, by which the participants' prevailing responses turn out not to support the generally…

Crupi, Vincenzo; Tentori, Katya; Lombardi, Luigi

2009-01-01

301

Versailles revisited  

Microsoft Academic Search

Manfred Boemeke, Gerald Feldman, and Elisabeth Glaser, The Treaty of Versailles: A Reassessment after 75 Years (New York: Cambridge University Press; and Washington, D.C.: German Historical Institute, 1998).

Marc Trachtenberg

2000-01-01

302

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

2013-10-01

303

Palatogram revisited.  

PubMed

It is the responsibility of the dentist to fabricate a denture that is fully functional and perfectly esthetic. One prime oral function that has always been overlooked in this regard is speech. It has been thought that speech will follow mere replacement of teeth and that it is the patient's duty to fine tune this function with practice. Phonetics, esthetics, function and comfort form the foundation of a successful prosthodontic treatment. Accurate approximation of palatal contours of a maxillary complete denture to a patient's tongue can improve speech intelligibility, if other factors such as tooth position, occlusal plane and occlusal vertical dimension are satisfactory. Customizing palatal contours of a maxillary complete denture can be accomplished by using tissue-conditioning material, which provides sufficient working time for a patient to pronounce a series of sibilant sounds while recording dynamic impression of the tongue. This article describes a technique of obtaining palatogram and customizing palatal contours of a maxillary complete denture with autopolymerizing acrylic resin to improve the intelligibility of speech. PMID:24808716

Jain, Ashish R; Venkat Prasad, M K; Ariga, Padma

2014-01-01

304

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

305

Cryojet Revisited.  

National Technical Information Service (NTIS)

The viability of a cryojet engine is evaluated for high Mach number applications. Cryojet is an advanced thermodynamic cycle that offers high specific impulse (to 5000 seconds), high thrust-to-weight ratio (up to 25:1) and increased Mach number capability...

B. Singh W. Roberts S. Harper

1990-01-01

306

Amyoplasia revisited.  

PubMed

Amyoplasia is a specific type and the most common form of arthrogryposis (multiple congenital contractures). It is a clinical diagnosis at this time. Care should be used making the diagnosis because of the implications for recurrence, natural history, associated anomalies, and both etiology and pathogenesis. We reviewed over 600 published reports and 2,500 individual records to identify the 560 individuals reported here. Affected limbs had characteristic positions with fatty-fibrous replacement of muscle. Upper limb involvement was usually characterized by extended elbows. Lower limbs were held in various positions at birth; however, equinovarus positioning of feet was almost always present. Symmetric involvement was common. Among 560 affected individuals, subtypes were identified: four-limb symmetric involvement (331/560 = 55.9%), severe involvement (41/560 = 7.3%), three-limb involvement (27/560 = 4.8%), upper limb only Amyoplasia (ULA; 94/560 = 16.8%), and lower limb only Amyoplasia (LLA; 25/560 = 15.5%). Discordant monozygotic twinning was increased, occurring in 6.6% (37/560; OR 10.9). A variety of additional anomalies were seen, attributed to apparent vascular compromise. Gastrointestinal vascular compromise-type anomalies were present in 9.1% (51/560), trunk muscle defects in another 2.7% (15/560), digit compromise in 12.1% (68/560), constriction rings in 4.3% (24/560), and perinatal long bone fractures in 10.5% (59/560). Although prenatal ultrasound became the standard of care in 1990, only about one quarter of affected pregnancies were diagnosed prenatally since 1990. Amyoplasia appears to be completely sporadic. Novel pathogenetic mechanisms for the congenital anomalies seen in Amyoplasia need to be identified. PMID:24459070

Hall, Judith G; Aldinger, Kimberly A; Tanaka, Kimi I

2014-03-01

307

Chondrosarcomas revisited.  

PubMed

Chondrosarcomas are malignant bone tumors with pure hyaline cartilage differentiation; myxoid changes, calcification, or ossification may be present. Several subtypes of chondrosarcomas exist. Behavior patterns vary, ranging from slow-growing nonmetastasizing lesions to aggressive metastasizing sarcomas. Symptoms are usually mild, with duration ranging from several months to years, and usually consist of persistent, dull, aching pain or palpable masses. Radiographic findings include bone expansion with cortical thickening, radiolucent areas with variably distributed punctate or ring-like matrix calcifications, cortical erosion or destruction, endosteal scalloping, and scant or absent periosteal reaction; extension into the soft tissue may be present. Histological differential diagnosis from benign cartilaginous lesions can be achieved by increased cellularity, enlarged plump nuclei, binucleated cells, hyperchromatic nuclear pleomorphism, and permeation of cortical or medullary bone. Atypia is usually mild to moderate; necrosis and mitoses can be seen, particularly in high-grade lesions. Adequate surgery is the mainstay of treatment. High-grade and pelvic chondrosarcomas are best managed with wide resection. Because of the low metastatic potential and low local recurrence rate noted with intralesional surgery, low-grade chondrosarcomas can be treated with curettage (with or without treatment of the defect cavity) with a local adjuvant, such as phenol or cryotherapy. Adjuvant chemotherapy may be considered for mesenchymal and dedifferentiated chondrosarcomas. Radiation therapy can be considered after incomplete resection or if resection is not feasible or would cause unacceptable morbidity. PMID:22385450

Mavrogenis, Andreas F; Gambarotti, Marco; Angelini, Andrea; Palmerini, Emanuela; Staals, Eric L; Ruggieri, Pietro; Papagelopoulos, Panayiotis J

2012-03-01

308

Cinderella revisited  

PubMed Central

Objective To examine the references to Cinderella in medical literature. Design Analysis of papers published in the past 50 years that mention Cinderella. Results The trend for use of Cinderella as a metaphor in medical publications is increasing exponentially. Five separate themes emerged: neglect, identity, transformation, exhaustion, and the mixed metaphor. Conclusions The medical use of the Cinderella fable is growing in popularity

Cameron, Stewart M

2005-01-01

309

Revisiting the \\  

Microsoft Academic Search

This paper constitutes an attempt to reframe and eventually deflate the ongoing “compliance-vs.-rebalancing” debate which has permeated WTO scholarship for the last 10 years. At face value, this controversy circles around object and purpose of WTO enforcement and the legal nature of dispute panels’ recommendations: Compliance advocates maintain that the objective of WTO enforcement is to induce compliance with DSB

Simon A. B. Schropp

2007-01-01

310

PACER revisited  

SciTech Connect

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 is contained in a cavity about 200 m in diameter, filled with 200 atm of 500/degree/C steam. Energy from the explosion is used to produce power, and the neutrons are used to produce materials such as /sup 233/U, Pu, /sup 60/Co, and T. 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 line the cavity with steel; replace the steam with molten salt; and reduce the explosive yield to about 2 kt. This concept is the only fusion power concept where the underlying technology is proven and in hand today. 9 refs., 3 figs., 1 tab.

Moir, R.W.

1988-10-04

311

Palatogram revisited  

PubMed Central

It is the responsibility of the dentist to fabricate a denture that is fully functional and perfectly esthetic. One prime oral function that has always been overlooked in this regard is speech. It has been thought that speech will follow mere replacement of teeth and that it is the patient's duty to fine tune this function with practice. Phonetics, esthetics, function and comfort form the foundation of a successful prosthodontic treatment. Accurate approximation of palatal contours of a maxillary complete denture to a patient's tongue can improve speech intelligibility, if other factors such as tooth position, occlusal plane and occlusal vertical dimension are satisfactory. Customizing palatal contours of a maxillary complete denture can be accomplished by using tissue-conditioning material, which provides sufficient working time for a patient to pronounce a series of sibilant sounds while recording dynamic impression of the tongue. This article describes a technique of obtaining palatogram and customizing palatal contours of a maxillary complete denture with autopolymerizing acrylic resin to improve the intelligibility of speech.

Jain, Ashish R.; Venkat Prasad, M. K.; Ariga, Padma

2014-01-01

312

Hubble Revisited  

NASA Astrophysics Data System (ADS)

Arguably the single most successful scientific instrument ever built, the Hubble Space telescope continues to dazzle. In recent months it has discovered the most distant known galaxy and the most massive known star, and has been at the front lines of all the most pressing questions in astrophysics: the age of the Universe, the nature of gamma-ray bursters, the discovery of extrasolar planets. In The Discovery Machine, the authors of the widely acclaimed Hubble: A New Window to the Universe bring you an exciting, detailed, gorgeously illustrated account of Hubble's breathtaking new discoveries. Acclaim for Hubble: A New Window to the Universe "Wonderful to behold. Buy it and feast your eyes." Scientific American "A wonderful volume...a clear and insightful explanation is included for each and every image." The Planetarian

Fischer, Daniel; Duerbeck, Hilmar; Hawley, S. A.; Jenkner, H.

313

Photons Revisited  

NASA Astrophysics Data System (ADS)

A systematic review of methods and data for the Monte Carlo simulation of photon interactions is in progress: it concerns a wide set of theoretical modeling approaches and data libraries available for this purpose. Models and data libraries are assessed quantitatively with respect to an extensive collection of experimental measurements documented in the literature to determine their accuracy; this evaluation exploits rigorous statistical analysis methods. The computational performance of the associated modeling algorithms is evaluated as well. An overview of the assessment of photon interaction models and results of the experimental validation are presented.

Batic, Matej; Begalli, Marcia; Han, Min Cheol; Hauf, Steffen; Hoff, Gabriela; Kim, Chan Hyeong; Kim, Han Sung; Grazia Pia, Maria; Saracco, Paolo; Weidenspointner, Georg

2014-06-01

314

Ortega Revisited.  

ERIC Educational Resources Information Center

Reexamines Ortega y Gasset's proposition that the professional role of the librarian is to act as a selective "filter between man and the torrent of books." Responsibilities of the librarian in light of the increasing volume of information, increases in speed of access to information, and information overload, are discussed. (Author/JL)

Asheim, Lester

1982-01-01

315

Marijuana Revisited.  

ERIC Educational Resources Information Center

This review examines recent research on psychological effects of marijuana. The article contains material on potency, research problems, use patterns in the United States, and expectancy, as well as a review of research on acute effects, including psychosis, toxic delirium, acute anxiety, and brain damage. (Author)

Archer, James, Jr.; Lopata, Ann

1979-01-01

316

Pronominalization revisited  

Microsoft Academic Search

Pronominalization has been related to the idea of a local focus - a set of discourse entities in the speaker's centre of attention, for example in Gundel et al. (1993)'s givenness hierarchy or in centering theory. Both accounts say that the determination of the focus depends on syntactic as well as pragmatic factors, but have not been able to pin

Renate Henschel; Hua Cheng; Massimo Poesio

2000-01-01

317

Globozoospermia revisited.  

PubMed

Globozoospermia is a rare (incidence <0.1%) but severe disorder in male infertility. Total globozoospermia is diagnosed by the presence of 100% round-headed spermatozoa lacking an acrosome. It is still unclear whether patients whose ejaculate contains both normal and globozoospermic cells (partial globozoospermia) suffer from a variation of the same syndrome. Apart from the fact that affected males suffer from reduced fertility or even infertility, no other physical characteristics can be associated with the syndrome. ICSI is a treatment option for these patients, although low fertilization rates after ICSI show a reduced ability to activate the oocyte. In globozoospermic cells, the use of acrosome markers has demonstrated an absent or severely malformed acrosome. Chromatin compaction appears to be disturbed but is not consistently over- or undercondensed. In some cases, an increased number of cells with DNA fragmentation have been observed. The analysis of the cytogenetic composition revealed an increased aneuploidy rate in some cases. Nonetheless, no increased number of spontaneous abortions or congenital defects has been reported in pregnancies conceived after ICSI. The pathogenesis of globozoospermia most probably originates in spermiogenesis, more specifically in acrosome formation and sperm head elongation. In several knockout mouse models, a phenotype similar to that in humans was found. Together with the occurrence of affected siblings, these findings indicate a genetic origin, which makes globozoospermia a good candidate for genetic analysis. More research is needed to elucidate the pathogenesis of human globozoospermia to further understand globozoospermia as well as (abnormalities in) spermiogenesis and spermatogenesis in general. PMID:17008355

Dam, A H D M; Feenstra, I; Westphal, J R; Ramos, L; van Golde, R J T; Kremer, J A M

2007-01-01

318

Dualism revisited  

Microsoft Academic Search

The problem of consciousness should eventually receive a scientific solution, but there are a number of scientific and philosophical obstacles along the way. I offer solutions to the philosophical problems and proposals for approaching the scientific problems.

John R. Searle

2007-01-01

319

Petaluma Revisited  

ERIC Educational Resources Information Center

If economic recovery occurs, land development and construction will revive simultaneously with land-use controls. Already the Federal government has affected land use by passing the Coastal Zone Management Act and the Clean Air Act. The states have also initiated land-use regulations concerning community planning and environmental quality. (MR)

Wolff, Anthony

1975-01-01

320

Intelligence Revisited.  

National Technical Information Service (NTIS)

This document is a draft of Chapter 19 from 'The Evolution of ROBART,' written by H. R. Everett of the Space and Naval Warfare Systems Command in San Diego, California. In this chapter, the author explores the theoretical upper limit of robotic intelligen...

H. R. Everett

2005-01-01

321

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

322

Ossiculoplasty: revisited.  

PubMed

Conductive hearing loss from ossicular chain abnormalities may result from either discontinuity or fixation of the ossicular chain. The ideal prosthesis for ossicular reconstruction should be biocompatible, stable, safe, readily available, and capable of yielding optimal sound transmission. At present ossiculoplasty techniques using alloplast materials are becoming popular but the fate of these synthetic materials in human middle ear requires further study. Autologous ossicle or cortical bone grafts maintain their morphologic contour, size, shape, and physical integrity for long periods of time, over 25 years making them still the choice at present. The choice of technique will still depend on the causative pathology, availability of graft, surgical experience. PMID:24427696

Mudhol, R S; Naragund, A I; Shruthi, V S

2013-12-01

323

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

324

pKa determination by (1)H NMR spectroscopy - An old methodology revisited.  

PubMed

pKa values of acids and protonated bases have an essential impact on organic synthesis, medicinal chemistry, and material and food sciences. In drug discovery and development, they are of utmost importance for the prediction of pharmacokinetic and pharmacodynamic properties. To date, various methods for the determination of pKa values are available, including UV-spectroscopic, potentiometric, and capillary electrophoretic techniques. An additional option is provided by nuclear magnetic resonance (NMR) spectroscopy. The underlying principle is the alteration of chemical shifts of NMR-active nuclei (e.g., (13)C and (1)H) depending on the protonation state of adjacent acidic or basic sites. When these chemical shifts are plotted against the pH, the inflection point of the resulting sigmoidal curve defines the pKa value. Although pKa determinations by (1)H NMR spectroscopy are reported for numerous cases, the potential of this approach is not yet fully evaluated. We therefore revisited this method with a diverse set of test compounds covering a broad range of pKa values (pKa 0.9-13.8) and made a comparison with four commonly used approaches. The methodology revealed excellent correlations (R(2)=0.99 and 0.97) with electropotentiometric and UV spectroscopic methods. Moreover, the comparison with in silico results (Epik and Marvin) also showed high correlations (R(2)=0.92 and 0.94), further confirming the reliability and utility of this approach. PMID:24462329

Bezençon, Jacqueline; Wittwer, Matthias B; Cutting, Brian; Smieško, Martin; Wagner, Bjoern; Kansy, Manfred; Ernst, Beat

2014-05-01

325

Orphan drugs for rare diseases: is it time to revisit their special market access status?  

PubMed

Orphan drugs are intended for diseases with a very low prevalence, and many countries have implemented legislation to support market access of orphan drugs. We argue that it is time to revisit the special market access status of orphan drugs. Indeed, evidence suggests that there is no societal preference for treating rare diseases. Although society appears to assign a greater value to severity of disease, this criterion is equally relevant to many common diseases. Furthermore, the criterion of equity in access to treatment, which underpins orphan drug legislation, puts more value on health improvement in rare diseases than in common diseases and implies that population health is not maximized. Finally, incentives for the development, pricing and reimbursement of orphan drugs have created market failures, including monopolistic prices and the artificial creation of rare diseases. We argue that, instead of awarding special market access status to orphan drugs, there is scope to optimize research and development (R&D) of orphan drugs and to control prices of orphan drugs by means of, for example, patent auctions, advance purchase commitments, pay-as-you-go schemes and dose-modification studies. Governments should consider carefully the right incentive strategy for R&D of orphan drugs in rare diseases. PMID:22747423

Simoens, Steven; Cassiman, David; Dooms, Marc; Picavet, Eline

2012-07-30

326

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

327

TGF production altitude - revisiting the BATSE spectra in view of upcoming missions  

NASA Astrophysics Data System (ADS)

Based on the RHESSI results it has been suggested that most of the X-rays are produced at very low altitudes. On the other hand the few published BATSE spectra show unabsorbed fluxes of X-rays in the 25-50 keV energy range, indicating that the production altitude of the X-rays is still an open question. As the soft X- rays are highly modified by photoelectric absorption on their way out of the atmosphere, we suggest that this is a key feature that can be utilized to determine at which altitude most of the X-rays are produced, although TGF measurements in the low energy range are still not available. In order to determine the most likely production altitude of TGFs we have revisited the BATSE spectra and modelled the X-ray propagation out of the atmosphere. The results are used to justify what kind of measurements that are needed to solve this problem and define requirements for upcoming missions like ASIM.

Ostgaard, N.; Stadsnes, J.; Gjesteland, T.; Connell, P. H.

2006-12-01

328

Revisiting the role of first trimester homocysteine as an index of maternal and fetal outcome.  

PubMed

AIM. To revisit the role of first trimester homocysteine levels with the maternal and fetal outcome. METHODS. This was a cohort study comprising 100 antenatal women between 8 and 12 weeks of gestation. Serum homocysteine levels were checked after overnight fasting. RESULTS. There were significantly elevated homocysteine levels among women with prior history of hypertensive disorders of pregnancy and prior second or third trimester pregnancy losses. There was no significant difference in homocysteine levels among women with previous gestational diabetes mellitus, preterm deliveries, or fetal malformations. Homocysteine levels were significantly elevated in those who developed hypertensive disorder of pregnancy, oligohydramnios, and meconium stained amniotic fluid, had a pregnancy loss, or delivered a low birth weight baby. There was no significant difference in homocysteine levels for those who developed gestational diabetes mellitus. CONCLUSIONS. Increased first trimester serum homocysteine is associated with history of pregnancy losses, hypertensive disorders of pregnancy, and preterm birth. This is also associated with hypertensive disorders of pregnancy, pregnancy loss, oligohydramnios, meconium stained amniotic fluid, and low birth weight in the current pregnancy. This trial is registered with ClinicalTrials.gov CTRI/2013/02/003441. PMID:24883207

Mascarenhas, Mariano; Habeebullah, Syed; Sridhar, M G

2014-01-01

329

The Galactic Cepheid period-luminosity relation revisited using bona fide cluster Cepheids  

NASA Astrophysics Data System (ADS)

Classical Cepheids in Galactic open clusters (cluster Cepheids: CCs) have been studied extensively for multiple decades, thanks to their importance as calibrators of the Galactic Cepheid period-luminosity relation (PLR). Here we revisit the calibration of the Galactic PLR using a new sample of CCs, since even recent calibrations show significant discrepancies. The CC sample employed for the calibration is based on the preliminary results of a self-consistent, eight-dimensional all-sky census. This census is based mostly on literature data, supplemented with high-precision radial-velocity observations from both hemispheres. New CCs are identified from our census and the degree of confidence in membership is quantified for known candidates. Using only bona fide CCs, we obtain MV = (-3.08 +/- 0.50) log P + (-0.94 +/- 0.42) mag, which is in perfect agreement with the results by Sandage, Tammann, and Reindl, albeit with larger error bars and an rms of 0.21 mag. The key to obtaining a meaningful calibration is to employ accurate cluster distance moduli and space reddening values. A homogeneous study of all bona fide host clusters would be desirable to increase precision and confidence in the calibration.

Anderson, Richard I.; Mowlavi, Nami; Eyer, Laurent

2013-02-01

330

Modeling the northern Adriatic double-gyre response to intense bora wind: A revisit  

NASA Astrophysics Data System (ADS)

A combination of recent intensive observations and simulations with two numerical models is used to revisit the issue of the northern Adriatic response to strong bora episodes. New observed and simulated data reinforce the view that an episode of strong bora wind provokes a double-gyre (cyclonic, Trieste, and anticyclonic, Rovinj) response north of the Po Delta - Pula line. During an intense bora episode, both measured and modeled statistics picture a downwind, highly polarized, and almost depth-independent flow within the Trieste gyre NW arm. Its NE arm maintains a sharp polarization and strong depth dependence while exhibiting lower speeds, with models in good accord with observations. The current statistics for Rovinj gyre provide lower maximum and average speed values and less polarized but still rather depth-independent flow, while exhibiting clockwise rotation. The north arm of the Senj gyre (positioned south of the Po Delta-Pula line) enjoys more lateral freedom, and exhibits less rectilinear flow. Our review reinforces the notion that modeling studies based on ECMWF wind forcing fail to properly take into account the orographic control of the Dinaric Alps, and to produce correct bora-induced gyral pattern. The COAMPS® model successfully simulated the onset, duration, and decay of the wind peaks, but exhibited a tendency to overpredict the strength of the bora wind. Our simulations have identified the shallow NW coastal strip as an important source of colder water observed in a sequence of remotely sensed SST fields derived from AVHRR data.

Kuzmi?, Milivoj; Janekovi?, Ivica; Book, Jeffrey W.; Martin, Paul J.; Doyle, James D.

2006-03-01

331

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

332

Revisiting the NIOSH Criteria for a Recommended Standard: Occupational Noise Exposure  

NASA Astrophysics Data System (ADS)

In 1998, the National Institute for Occupational Safety and Health (NIOSH) revised the Criteria for a Recommended Standard: Occupational Noise Exposure [DHHS (NIOSH) Publication No. 98-126]. NIOSH reevaluated the recommended exposure limit (REL) for occupational noise exposure and reaffirms support for 85-dBA REL. Based upon scientific evidence, NIOSH recommends a 3-dB exchange rate. NIOSH recommends that significant threshold shift be identified as an increase of 15 dB in the hearing threshold level at 500, 1000, 2000, 3000, 4000, or 6000 Hz in either ear, with two consecutive audiometric tests. The new criterion has the advantages of a high identification rate and a low false-positive rate. In contrast with the former 1972 criterion, NIOSH no longer recommends age correction on individual audiograms. NIOSH has revisited its recommendations on the using of single-number laboratory-derived Noise Reduction Rating (NRR) required by the U.S. Environmental Protection Agency for labeling of hearing protectors sold within the United States. In 1972, NIOSH recommended the use of the full NRR value; however, the new criterion recommends derating the NRR by 25%, 50%, and 70% for earmuffs, formable earplugs, and all other earplugs, respectively. This presentation will compare and contrast current regulations against the NIOSH recommendations.

Murphy, William J.; Franks, John R.

2002-05-01

333

Revisiting the carousel and non-radial oscillation models for pulsar B0809+74  

NASA Astrophysics Data System (ADS)

Recent interest in pulsar B0809+74, well known for its highly accurate drifting subpulses and `memory across nulls' has raised questions about the adequacy of the rotating subbeam-carousel or/and non-radial oscillation models to describe this phenomenon. The success of the subbeam-carousel model in explaining the drift modes and periodic nulls in B1918+19 has encouraged us to revisit the application of this model to B0809+74. Pulsar B0809+74 is a complicated object, as are many pulsars where our sightline grazes the conal beam edge obliquely. Its subpulses also exhibit complex modal polarization, and only analysing the total power paints an incomplete picture of emission from the star. This remarkable pulsar has, however, been studied in great detail for over three decades, and many of the earlier controversies about its characteristics have largely been resolved. In this paper, we demonstrate that the carousel model is highly successful in reproducing the behaviour of B0809+74 in every heuristic and geometric manner. In addition, Rosen and Demorest have quantitatively fitted a non-radial oscillation model to B0809+74 at a single frequency, and we discuss how this model can reproduce the behaviour of B0809+74 across a much larger band.

Rankin, Joanna; Rosen, Rachel

2014-03-01

334

Revisiting the implications of CPT and unitarity for baryogenesis and leptogenesis  

NASA Astrophysics Data System (ADS)

In the context of Grand Unified Theories (GUT) baryogenesis models, a well-known theorem asserts that CPT conservation and the unitarity of the S matrix require that the lowest order contribution that leads to the generation of a nonzero net CP violation via the decay of a heavy particle must be to O(?B3), where ?B is a baryon number (B) violating coupling. We revisit this theorem [which holds for lepton number (L) violation, and hence for leptogenesis as well] and examine its implications for models where the particle content allows the heavy particle to also decay via modes which conserve B (or L) in addition to modes which do not. We systematically expand the S matrix order by order in B/L violating couplings, and show, in such cases, that the net CP violation is nonzero even to O(?2), without actually contradicting the theorem. By replacing a B/L violating coupling (usually constrained to be small) by a relatively unconstrained B/L conserving one, our result may allow for sufficient CP violation in models where it may otherwise have been difficult to generate the observed baryon asymmetry. As an explicit application of this result, we construct a model in low-scale leptogenesis.

Bhattacharya, Atri; Gandhi, Raj; Mukhopadhyay, Satyanarayan

2014-06-01

335

Gray and green revisited: a multidisciplinary perspective of gardens, gardening, and the aging process.  

PubMed

Over fourteen years ago, the concept of "gray and green" was first introduced by Wright and Lund (2000) to represent a new awareness and a call for increased scholarship at the intersection of environmental issues and the aging process. This review paper revisits that concept with a fresh perspective on the specific role of gardens and gardening in the aging experience. As example, gardening is one of the most popular home-based leisure activities in the US and represents an important activity in the lives of older adults in a variety of residential settings. Yet, there has been a lack of any comprehensive and multidisciplinary (science and humanities) examination of the nexus between gardening and the aging experience, and in particular with research connections to stewardship and caring. In this paper, we review contemporary articles demonstrating the multidisciplinarity of gardening and the aging process. First, we will focus on the beneficial psychological effects resulting from the cultivation of caring, including personal contentment and artistic expression. Second, we will focus on stewardship and how gardening increases health, community awareness, and a connection to future generations. On the surface, this may demonstrate a separation between the humanities and science, but we will clarify a symbiotic relationship between the two disciplines in our conclusion. PMID:24734179

Wright, Scott D; Wadsworth, Amy Maida

2014-01-01

336

Gray and Green Revisited: A Multidisciplinary Perspective of Gardens, Gardening, and the Aging Process  

PubMed Central

Over fourteen years ago, the concept of “gray and green” was first introduced by Wright and Lund (2000) to represent a new awareness and a call for increased scholarship at the intersection of environmental issues and the aging process. This review paper revisits that concept with a fresh perspective on the specific role of gardens and gardening in the aging experience. As example, gardening is one of the most popular home-based leisure activities in the US and represents an important activity in the lives of older adults in a variety of residential settings. Yet, there has been a lack of any comprehensive and multidisciplinary (science and humanities) examination of the nexus between gardening and the aging experience, and in particular with research connections to stewardship and caring. In this paper, we review contemporary articles demonstrating the multidisciplinarity of gardening and the aging process. First, we will focus on the beneficial psychological effects resulting from the cultivation of caring, including personal contentment and artistic expression. Second, we will focus on stewardship and how gardening increases health, community awareness, and a connection to future generations. On the surface, this may demonstrate a separation between the humanities and science, but we will clarify a symbiotic relationship between the two disciplines in our conclusion.

Wright, Scott D.; Wadsworth, Amy Maida

2014-01-01

337

COPS science questions revisited: What have we learned so far from COPS?  

NASA Astrophysics Data System (ADS)

The Convective and Orographically-induced Precipitation Study (COPS) was an international field campaign carried out in summer 2007 with the overall goal to advance the quality of forecasts of orographically-induced convective precipitation by 4-dimensional observations and modeling of its life cycle. The pre-convective environment, the formation of clouds and the onset and development of precipitation were observed in a low-mountain area in south-western Germany and eastern France covering the Vosges Mountains, the Rhine Valley, and the Black Forest Mountains during 18 Intensive Observations Periods from June 1 to August 31, 2007, under different forcing conditions. Meanwhile, in the nearly five years since the COPS field phase, a large number of results on analyses of selected COPS IOPs and of continuous measurements during the COPS period have been published; in a special issue of the Quarterly Journal of the Royal Meteorological Society alone, 21 papers appeared in January 2011. A second special issue on COPS results is currently in preparation for the Meteorologische Zeitschrift (MetZ). In this contribution, we will revisit the original science questions of COPS, summarize the results gained so far from COPS, and discuss questions which still remain open.

Behrendt, A.; Wulfmeyer, V.; Kottmeier, Ch.; Richard, E.; Dorninger, M.; Di Girolamo, P.; Corsmeier, U.; Kalthoff, N.; Bauer, H.-S.

2012-04-01

338

Pulmonary Function Studies of Healthy Non-smoking Male University Students of Kolkata, India -- Revisited  

PubMed Central

Background: Pulmonary function tests (PFTs) need to be revisited in light of rapid economic growth and industrial development. Questions have been raised about the validity of existing population-specific norms for predicting PFTs, and therefore, the present study aimed to determine the applicability of existing norms for PFTs in young healthy non-smoking male university students of Kolkata. Methods: PFTs were carried out for 87 non-smoking male university students who were randomly sampled from the University of Calcutta, Kolkata, India. Results: The PFTs data obtained in this study did not show a significant variation with that obtained in a previous study. Significant (P < 0.001) differences in the forced expiratory volume in 1 s (FEV1%) and peak expiratory flow rate (PEFR) between the two studies may be attributed to differences in the age and body height, which exhibited significant correlations with the vital capacity (VC), forced vital capacity (FVC), FEV1, FEV1%, and PEFR. Regression equations have been computed to predict PFTs parameters from age and body height. Conclusion: Pulmonary function in the university students of Kolkata was found to have remained mostly unchanged in the last 24 years. The equations computed in this study are considered preferable owing to their substantially smaller standard error of estimate (SEE) than those proposed in the previous study.

Bandyopadhyay, Amit; Bhattacharjee, Ishita; Dalui, Rishna; Pal, Sangita

2013-01-01

339

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

SciTech Connect

Measurements of the total ion yield (TIY) x-ray absorption spectrum (XAS) of liquid water by Wilson et al. (2002 J. Phys.: Condens. Matter 14 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 of the liquid water surface. However, our new results indicate that the previously obtained spectrum may have suffered from as yet unidentified experimental artifacts. Although computational results indicate that the liquid water surface should exhibit a TIY-XAS that is fundamentally distinguishable from the bulk liquid XAS, the new experimental results suggest that the observable TIY-XAS is actually nearly identical in appearance to the total electron yield (TEY-)XAS, which is a bulk probe. This surprising similarity between the observed TIY-XAS and TEY-XAS likely results from large contributions from x-ray induced electron stimulated desorption of ions, and does not necessarily indicate that the electronic structure of the bulk liquid and liquid surface are identical.

Saykally, Richard J; Cappa, Chris D.; Smith, Jared D.; Wilson, Kevin R.; Saykally, Richard J.

2008-02-16

340

FUV Spectra of Evolved Late-K and M Stars: Mass Loss Revisited and Stellar Activity  

NASA Technical Reports Server (NTRS)

This is the final report for the FUSE Cycle 1 program A100: FUV Spectra of Evolved Late-K and M Stars: Mass Loss revisited and Stellar Activity. Targets alpha TrA (K3 II) and gamma Cru (M3 III) were originally assigned 25 ksec each, to be observed in the medium aperture. Once the in-flight performance and telescope alignment problems were known, the observations were reprogrammed to optimized the scientific return of the program. Alpha TrA was scheduled for 25 ksec observations in both the medium and large apertures. The principle aim of this program was to measure the stellar FUV line and continuum emission, in order to estimate the photoionization radiation field and to determine the level of stellar activity through the fluxes in the collisionally excited high temperature diagnostics: C III 977Angstroms and O VI 1032,1038Angstrom doublet. The medium aperture observations were obtained successfully while the large aperture observations were thought by Johns Hopkins University (JHU)to be lost to satellite problems. There was insufficient signal-to- noise in the medium aperture short wavelength Sic channels to do quantitative science.

Harper, Graham M.

2002-01-01

341

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

342

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

343

Revisit of Alfvén ballooning modes in isotropic, ideal MHD plasmas: Effect of diamagnetic condition  

NASA Astrophysics Data System (ADS)

Alfvén ballooning modes provide an important mechanism to explain explosive phenomena in regions where field lines transit from dipole-like to taillike shapes. However, commonly used analytical results were unable to recover Alfvén modes in uniform plasmas and basic ballooning mode in inhomogeneous plasmas. We rigidly revisited previous work on isotropic, ideal magnetospheric plasmas and found where the problems occurred. This paper shows accurate expressions of the ballooning modes. Under the dimagnetic condition (an infinite ky), the modes have two groups depending on the relations of the three equilibrium parameters: plasma ?, pressure gradient kp, and magnetic curvature kc (magnetic gradient kB is no more than a tenth of kc and thus neglected in magnetotail plasma). If the constraint is relaxed (a finite ky), the dispersion relation includes the following: (1) the fast compressional Alfvén branch; (2) two groups of ballooning instabilities: Group 1 appears when kp is independent of ?, and Group 2 emerges when kc is independent of ?; and (3) in Group 1, a critical ? exists above which the wave mode becomes unstable, while the perpendicular wave number (k?) affects the instability by modulating the critical ? values; by contrast, in Group 2, there is no critical ?, and the wave keeps its original stable or unstable mode, while k? has a critical value above which the wave mode becomes unstable.

Ma, John Z. G.; Hirose, Akira

2014-04-01

344

Nuclear magnetic resonance signal dynamics of liquids in the presence of distant dipolar fields, revisited.  

PubMed

The description of the nuclear magnetic resonance magnetization dynamics in the presence of long-range dipolar interactions, which is based upon approximate solutions of Bloch-Torrey equations including the effect of a distant dipolar field, has been revisited. New experiments show that approximate analytic solutions have a broader regime of validity as well as dependencies on pulse-sequence parameters that seem to have been overlooked. In order to explain these experimental results, we developed a new method consisting of calculating the magnetization via an iterative formalism where both diffusion and distant dipolar field contributions are treated as integral operators incorporated into the Bloch-Torrey equations. The solution can be organized as a perturbative series, whereby access to higher order terms allows one to set better boundaries on validity regimes for analytic first-order approximations. Finally, the method legitimizes the use of simple analytic first-order approximations under less demanding experimental conditions, it predicts new pulse-sequence parameter dependencies for the range of validity, and clarifies weak points in previous calculations. PMID:19425789

Barros, Wilson; Gochberg, Daniel F; Gore, John C

2009-05-01

345

Keratinocyte detachment-differentiation connection revisited, or anoikis-pityriasi nexus redux.  

PubMed

Epidermis, a continuously self-renewing and differentiating organ, produces a protective stratum corneum that shields us from external chemical, physical and microbial threats. Epidermal differentiation is a multi-step process regulated by influences, some unknown, others insufficiently explored. Detachment of keratinocytes from the basement membrane is one such pro-differentiation stimulus. Here, we define the transcriptional changes during differentiation, especially those caused by detachment from the substratum. Using comprehensive transcriptional profiling, we revisited the effects of detachment as a differentiation signal to keratinocytes. We identified the genes regulated by detachment, the corresponding ontological categories and, using metaanalysis, compared the genes and categories to those regulated by other pro-differentiating stimuli. We identified 762 genes overexpressed in suspended keratinocyte, including known and novel differentiation markers, and 1427 in attached cells, including basal layer markers. Detachment induced epidermis development, cornification and desmosomal genes, but also innate immunity, proliferation inhibitors, transcription regulators and MAPKs; conversely the attached cells overexpressed cell cycle, anchoring, motility, splicing and mitochondrial genes, and both positive and negative regulators of apoptosis. Metaanalysis identified which detachment-regulated categories overlap with those induced by suprabasal location in vivo, by reaching confluency in vitro, and by inhibition of JUN kinases. Attached and in vivo basal cells shared overexpression of mitochondrial components. Interestingly, melanosome trafficking components were also overexpressed in the attached and in vivo basal keratinocytes. These results suggest that specific pro-differentiation signals induce specific features of the keratinization process, which are in vivo orchestrated into harmonious epidermal homeostasis. PMID:24960166

Banno, Tomohiro; Blumenberg, Miroslav

2014-01-01

346

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

347

Anion production in high-velocity cluster-atom collisions; the electron capture process revisited  

NASA Astrophysics Data System (ADS)

Anion production cross sections in collisions between Cn+, Cn carbon clusters (n ? 5) and helium atoms have been measured in high-velocity collisions (v = 2.25 and 2.6 au). This paper focuses on two of the three processes responsible for the Cn- production, namely double electron capture (DEC) onto Cn+ cations and single electron capture onto neutral (SECN) Cn. They were experimentally distinguished from a gaseous thickness dependence study. Dissociative and non-dissociative cross sections were measured and, in the case of DEC, all dissociative branching ratios measured; for these small systems, the C2- fragment was found magical. Data concerning electron capture in neutral-neutral collisions are extremely rare, especially at high velocity. Introduction of this measured process in the independent atom and electron (IAE) model allowed us to revisit and satisfactorily reproduce the so-far unexplained size evolution of single electron capture (SEC) cross sections in 2.6 au Cn+-He (n ? 10) collisions (Chabot et al 2006 J. Phys. B: At. Mol. Opt. Phys. 39 2593-603). IAE calculations for DEC cross sections and their comparison with experiment suggest a loss of electron in anionic Cn- species after the collision, competing with fragmentation and depending on the size.

Béroff, K.; Chabot, M.; Martinet, G.; Pino, T.; Bouneau, S.; Le Padellec, A.; Féraud, G.; Do Thi, N.; Calvo, F.; Bordas, C.; Lépine, F.

2013-01-01

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

Peripheral biomarkers revisited: integrative profiling of peripheral samples for psychiatric research.  

PubMed

Peripheral samples, such as blood and skin, have been used for decades in psychiatric research as surrogates for central nervous system samples. Although the validity of the data obtained from peripheral samples has been questioned and other state-of-the-art techniques, such as human brain imaging, genomics, and induced pluripotent stem cells, seem to reduce the value of peripheral cells, accumulating evidence has suggested that revisiting peripheral samples is worthwhile. Here, we re-evaluate the utility of peripheral samples and argue that establishing an understanding of the common signaling and biological processes in the brain and peripheral samples is required for the validity of such models. First, we present an overview of the available types of peripheral cells and describe their advantages and disadvantages. We then briefly summarize the main achievements of omics studies, including epigenome, transcriptome, proteome, and metabolome analyses, as well as the main findings of functional cellular assays, the results of which imply that alterations in neurotransmission, metabolism, the cell cycle, and the immune system may be partially responsible for the pathophysiology of major psychiatric disorders such as schizophrenia. Finally, we discuss the future utility of peripheral samples for the development of biomarkers and tailor-made therapies, such as multimodal assays that are used as a battery of disease and trait pathways and that might be potent and complimentary tools for use in psychiatric research. PMID:24286759

Hayashi-Takagi, Akiko; Vawter, Marquis P; Iwamoto, Kazuya

2014-06-15

350

Revisiting the Role of First Trimester Homocysteine as an Index of Maternal and Fetal Outcome  

PubMed Central

Aim. To revisit the role of first trimester homocysteine levels with the maternal and fetal outcome. Methods. This was a cohort study comprising 100 antenatal women between 8 and 12 weeks of gestation. Serum homocysteine levels were checked after overnight fasting. Results. There were significantly elevated homocysteine levels among women with prior history of hypertensive disorders of pregnancy and prior second or third trimester pregnancy losses. There was no significant difference in homocysteine levels among women with previous gestational diabetes mellitus, preterm deliveries, or fetal malformations. Homocysteine levels were significantly elevated in those who developed hypertensive disorder of pregnancy, oligohydramnios, and meconium stained amniotic fluid, had a pregnancy loss, or delivered a low birth weight baby. There was no significant difference in homocysteine levels for those who developed gestational diabetes mellitus. Conclusions. Increased first trimester serum homocysteine is associated with history of pregnancy losses, hypertensive disorders of pregnancy, and preterm birth. This is also associated with hypertensive disorders of pregnancy, pregnancy loss, oligohydramnios, meconium stained amniotic fluid, and low birth weight in the current pregnancy. This trial is registered with ClinicalTrials.gov CTRI/2013/02/003441.

Habeebullah, Syed; Sridhar, M. G.

2014-01-01

351

Structure of ketene - Revisited re (equilibrium) and rm (mass-dependent) structures  

NASA Astrophysics Data System (ADS)

The structure of ketene has been revisited on the basis of five new investigated isotopologues which, added to the existing six, rise their number to eleven. This gives an useful basis for new discussions about the structure. The quadratic, cubic and semi-diagonal quartic force field of ketene has been calculated at the MP2 level of theory employing a basis set of triple- ? quality. A semi-experimental equilibrium structure has been derived from experimental ground state rotational constants and rovibrational interaction parameters calculated from the ab initio force field. This structure is in excellent agreement with the ab initio structure calculated at the CCSD(T) level of theory using a basis set of quintuple- ? quality and a core correlation correction. The empirical structures including the mass-dependent rm structures have also been determined and their accuracy is discussed. The rm(1rL) method is the most stable under several testing conditions. However, the results are still not fully satisfactory. This is mainly due to the small coordinate of the keto-carbon.

Guarnieri, Antonio; Demaison, Jean; Rudolph, Heinz Dieter

2010-04-01

352

Revisiting annual mean and seasonal cycle of deep meridional overturning circulation of the Indian Ocean  

NASA Astrophysics Data System (ADS)

The annual mean and seasonal cycle of the deep meridional overturning circulation (MOC) of the Indian Ocean is being revisited here using GECCO synthesis. Resulting from ocean general circulation models, the annual mean deep MOC of the Indian Ocean are generally weak with inflow in the bottom layer and outflow in the intermediate and upper layer mixing with strong Indonesian Throughflow. For seasonal cycle of deep MOC, two significant and seasonal reversed counter-rotating deep cells over full depth of water column, roughly separated by 20S, are revealed during boreal summer and winter. The coincidences of the latitude 20S with where the maximum climatological wind curl for most of seasons reveals intimate relations between the deep meridional overturning and surface winds. Dynamical decompositions on annual mean and complete seasonal cycle of the meridional overturning show varying relative contribution of each dynamical component at different time scale. For annual mean deep MOC, Ekman dynamics is found to be dominant in the region of north of 25S, particularly in upper 3000m, whereas south of 25S external and vertical shear components show remarkable "seamount" features and are compensated with much larger strengths because of topo-modulated strong western boundary topography. At seasonal time scale, dominant role of Ekman dynamics and secondary role of external mode are found in the deep cell north of 20S in January and July. However in transition seasons, vertical shear is responsible for major part of meridional overturning and Ekman dynamics has comparable contribution north of Equator.

Wang, Weiqiang; Xie, Qiang; Li, Sha; Zhu, Xiuhua

2014-05-01

353

Revisiting the location and environment of the central engine in NGC 1068  

NASA Astrophysics Data System (ADS)

We revisit in this paper the location of the various components observed in the AGN of NGC 1068. Discrepancies between previously published studies are explained, and a new measurement for the absolute location of the K-band emission peak is provided. It is found to be consistent with the position of the central engine as derived by Gallimore et al. (1997), Capetti et al. (1997) and Kishimoto (1999). A series of map overlays is then presented and discussed. Model predictions of dusty tori show that the nuclear unresolved NIR-MIR emission is compatible with a broad range of models: the nuclear SED alone does not strongly constrain the torus geometry, while placing reasonable constraints on its size and thickness. The extended MIR emission observed within the ionizing cone is shown to be well explained by the presence of optically thick dust clouds exposed to the central engine radiation and having a small covering factor. Conversely, a distribution of diffuse dust particles within the ionizing cone is discarded. A simple model for the H2 and CO emission observed perpendicularly to the axis of the ionizing cone is proposed. We show that a slight tilt between the molecular disc and the Compton thick central absorber naturally reproduces the observed distribution of H2 of CO emission.

Galliano, E.; Alloin, D.; Granato, G. L.; Villar-Martín, M.

2003-12-01

354

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

355

Keratinocyte Detachment-Differentiation Connection Revisited, or Anoikis-Pityriasi Nexus Redux  

PubMed Central

Epidermis, a continuously self-renewing and differentiating organ, produces a protective stratum corneum that shields us from external chemical, physical and microbial threats. Epidermal differentiation is a multi-step process regulated by influences, some unknown, others insufficiently explored. Detachment of keratinocytes from the basement membrane is one such pro-differentiation stimulus. Here, we define the transcriptional changes during differentiation, especially those caused by detachment from the substratum. Using comprehensive transcriptional profiling, we revisited the effects of detachment as a differentiation signal to keratinocytes. We identified the genes regulated by detachment, the corresponding ontological categories and, using metaanalysis, compared the genes and categories to those regulated by other pro-differentiating stimuli. We identified 762 genes overexpressed in suspended keratinocyte, including known and novel differentiation markers, and 1427 in attached cells, including basal layer markers. Detachment induced epidermis development, cornification and desmosomal genes, but also innate immunity, proliferation inhibitors, transcription regulators and MAPKs; conversely the attached cells overexpressed cell cycle, anchoring, motility, splicing and mitochondrial genes, and both positive and negative regulators of apoptosis. Metaanalysis identified which detachment-regulated categories overlap with those induced by suprabasal location in vivo, by reaching confluency in vitro, and by inhibition of JUN kinases. Attached and in vivo basal cells shared overexpression of mitochondrial components. Interestingly, melanosome trafficking components were also overexpressed in the attached and in vivo basal keratinocytes. These results suggest that specific pro-differentiation signals induce specific features of the keratinization process, which are in vivo orchestrated into harmonious epidermal homeostasis.

Banno, Tomohiro; Blumenberg, Miroslav

2014-01-01

356

Revisiting the role of exact exchange in DFT spin-state energetics of transition metal complexes.  

PubMed

The effect of the exact exchange on the spin-state energetics of transition metal complexes is revisited with an attempt to clarify its origin and with regard to performance of DFT methods. Typically, by increasing an amount of the exact exchange in an exchange-correlation functional, higher spin states are strongly stabilized with respect to lower spin states. But this is not always the case, as revealed from the presented studies of heme and non-heme complexes, and of metal cations surrounded by point charges. It is argued that the sensitivity of the DFT spin-state energetics to the exact exchange admixture is rooted in the DFT description of the metal-ligand bonding rather than of the metal-centered exchange interactions. In the typical case, where transition from a lower spin state to a higher spin state involves an electron promotion from a nonbonding to an antibonding orbital, the lower spin state has a more delocalized charge distribution and contains a larger amount of nondynamical correlation energy than the higher spin state. However, DFT methods have problems with describing these two effects accurately. This interpretation allows us to explain why the exact exchange admixture has a much smaller effect on the energetics of spin transitions that involve only nonbonding d orbitals. PMID:24604025

Rado?, Mariusz

2014-06-25

357

Revisiting Low Energy Deuteron Production of [18F] Fluoride and Fluorine for PET  

SciTech Connect

Fluorine-18 is currently the most widely used radioisotope in PET imaging. While much attention has been paid in recent years to production methods from 18O(p,n)18F, the current work revisits production techniques using non-enriched neon targets and the 20Ne(d,{alpha})18F reaction. While this reaction was originally pursued, and ultimately replaced by the higher yielding 18O reactions, there is an opportunity using high current low-energy deuteron accelerators and the inherent simplicity of gas targetry to provide viable alternatives to the costly 18O water target systems. 18F production systems have been developed for the gas-phase 20Ne(d,{alpha})18F reaction with deuterons from a 3MV NEC 9SDH-2 electrostatic tandem accelerator. High power target systems allowing for irradiation in excess of 100uA provided [18F]F2 yields to 86% of the theoretical maximum, and [18F]F- yields with a wash-off system of 80% of the maximum.

Barnhart, T.E.; Nickles, R.J. [Medical Physics Department, University of Wisconsin, Madison, Wisconsin, 1500 North Highland Ave., Waisman Center, Madison, WI 53705 (United States); Roberts, A.D. [Medical Physics Department, University of Wisconsin, Madison, Wisconsin, 1500 North Highland Ave., Waisman Center, Madison, WI 53705 (United States); Psychiatry Department, University of Wisconsin, Madison, Wisconsin, 1500 North Highland Ave., Waisman Center, Madison, WI 53705 (United States)

2003-08-26

358

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

359

Steric and mass-induced sea level variations in the Mediterranean Sea revisited  

NASA Astrophysics Data System (ADS)

The total sea level variation (SLV) is the combination of steric and mass-induced SLV, whose exact shares are key to understanding the oceanic response to climate system changes. Total SLV can be observed by radar altimetry satellites such as TOPEX/POSEIDON and Jason 1/2. The steric SLV can be computed through temperature and salinity profiles from in situ measurements or from ocean general circulation models (OGCM), which can assimilate the said observations. The mass-induced SLV can be estimated from its time-variable gravity (TVG) signals. We revisit this problem in the Mediterranean Sea estimating the observed, steric, and mass-induced SLV, for the latter we analyze the latest TVG data set from the GRACE (Gravity Recovery and Climate Experiment) satellite mission launched in 2002, which is 3.5 times longer than in previous studies, with the application of a two-stage anisotropic filter to reduce the noise in high-degree and -order spherical harmonic coefficients. We confirm that the intra-annual total SLV are only produced by water mass changes, a fact explained in the literature as a result of the wind field around the Gibraltar Strait. The steric SLV estimated from the residual of "altimetry minus GRACE" agrees in phase with that estimated from OGCMs and in situ measurements, although showing a higher amplitude. The net water fluxes through both the straits of Gibraltar and Sicily have also been estimated accordingly.

GarcíA-GarcíA, D.; Chao, B. F.; Boy, J.-P.

2010-12-01

360

Revisiting the universality of (multiple) star formation in present-day star formation regions  

NASA Astrophysics Data System (ADS)

Populations of multiple stars inside clustered regions are known to change through dynamical interactions. The efficiency of binary disruption is thought to be determined by stellar density. King and collaborators recently investigated the multiplicity properties in young star-forming regions and in the Galactic field. They concluded that stellar-density-dependent modification of a universal initial binary population (the standard or null hypothesis model) cannot explain the observations. We revisit their results, analysing the data within the framework of different model assumptions, namely non-universality without dynamical modification and universality with dynamics. We illustrate that the standard model does account for all known populations if regions were significantly denser in the past. Some of the effects of using present-day cluster properties as proxies for their past values are emphasized and that the degeneracy between age and density of a star-forming region cannot be omitted when interpreting multiplicity data. A new analysis of the Corona Australis region is performed within the standard model. It is found that this region is likely as unevolved as Taurus and an initial density of ?190 M? pc-3 is required to produce the presently observed binary population, which is close to its present-day density.

Marks, Michael; Leigh, Nathan; Giersz, Mirek; Pfalzner, Susanne; Pflamm-Altenburg, Jan; Oh, Seungkyung

2014-07-01

361

The rotational spectrum of hydrogen sulfide: The H2S and H2S isotopologues revisited  

NASA Astrophysics Data System (ADS)

The rotational spectra of two isotopic species of hydrogen sulfide have been revisited. For H2S, which was detected in natural abundance, accurate measurements were performed in the submillimeter-wave region, from 500 GHz up to 1.56 THz, thus allowing improvement of the spectroscopic parameters as well as determination of new high-order centrifugal-distortion constants. The rotational spectrum of the main isotopologue was investigated in the millimeter- and submillimeter-wave region up to 1.6 THz, employing the Lamb-dip technique to obtain sub-Doppler resolution. As a consequence, transition frequencies at 1 THz were retrieved with an accuracy of 1 kHz and the hyperfine structure due to hydrogens was resolved, thus allowing the first determination of the spin–rotation tensor of H in H2S. Improved and new spectroscopic parameters were then provided that allow accurate predictions of rotational transitions up to 20 THz; in particular, the newly determined constants permit prediction of rotational transitions with J < 15, Ka<12 (up to about 10 THz) with expected uncertainties of a few hundreds of kHz.

Cazzoli, Gabriele; Puzzarini, Cristina

2014-04-01

362

Iron deficiency in the elderly population, revisited in the hepcidin era  

PubMed Central

Iron deficiency (ID) is relatively common among the elderly population, contributing substantially to the high prevalence of anemia observed in the last decades of life, which in turn has important implications both on quality of life and on survival. In elderly subjects, ID is often multifactorial, i.e., due to multiple concurring causes, including inadequate dietary intake or absorption, occult bleeding, medications. Moreover, because of the typical multimorbidity of aged people, other conditions leading to anemia frequently coexist and make diagnosis of ID particularly challenging. Treatment of ID is also problematic in elderly, since response to oral iron is often slow, with a substantial fraction of patients showing refractoriness and requiring cumbersome intravenous administration. In the last decade, the discovery of the iron regulatory hormone hepcidin has revolutionized our understanding of iron pathophysiology. In this review, we revisit ID among elderly people in the light of the impressive recent advances on knowledge of iron regulation, and discuss how hepcidin may help in diagnosis and treatment of this common clinical condition.

Busti, Fabiana; Campostrini, Natascia; Martinelli, Nicola; Girelli, Domenico

2014-01-01

363

18F-Fluorodeoxyglucose Uptake and Tumor Hypoxia: Revisit 18F-Fluorodeoxyglucose in Oncology Application  

PubMed Central

This study revisited 18F-fluorodeoxyglucose (18F-FDG) uptake and its relationship to hypoxia in various tumor models. METHODS: We generated peritoneal carcinomatosis and subcutaneous xenografts of colorectal cancer HT29, breast cancer MDA-MB-231, and non–small cell lung cancer A549 cell lines in nude mice. The partial oxygen pressure (pO2) of ascites fluid was measured. 18F-FDG accumulation detected by digital autoradiography was related to tumor hypoxia visualized by pimonidazole binding and glucose transporter-1 (GLUT-1) in frozen tumor sections. RESULTS: Ascites pO2 was 0.90 ± 0.53 mm Hg. Single cancer cells and clusters suspended in ascites fluid as well as submillimeter serosal tumors stained positive for pimonidazole and GLUT-1 and had high 18F-FDG uptake. In contrast, 18F-FDG uptake was significantly lower in normoxic portion (little pimonidazole binding or GLUT-1 expression) of larger serosal tumors or subcutaneous xenografts, which was not statistically different from that in the liver. CONCLUSIONS: Glucose demand (18F-FDG uptake) in severely hypoxic ascites carcinomas and hypoxic portion of larger tumors is significantly higher than in normoxic cancer cells. Warburg effect originally obtained from Ehrlich ascites carcinoma may not apply to normoxic cancer cells. Our findings may benefit the better understanding of 18F-FDG PET in oncology application.

Li, Xiao-Feng; Du, Yang; Ma, Yuanyuan; Postel, Gregory C.; Civelek, A. Cahid

2014-01-01

364

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

365

Revisiting the Lissajous figure as a tool to study bistable perception.  

PubMed

During bistable vision perception spontaneously "switches" between two mutually exclusive percepts despite constant sensory input. The endogenous nature of these perceptual transitions has motivated extensive research aimed at the underlying mechanisms, since spontaneous perceptual transitions of bistable stimuli should in principle allow for a dissociation of processes related to sensory stimulation from those related to conscious perception. However, transitions from one conscious percept to another are often not instantaneous, and participants usually report a considerable amount of mixed or unclear percepts. This feature of bistable vision makes it difficult to isolate transition-related visual processes. Here, we revisited an ambiguous depth-from-motion stimulus which was first introduced to experimental psychology more than 80 years ago. This rotating Lissajous figure might prove useful in complementing other bistable stimuli, since its perceptual transitions only occur at critical stimulus configurations and are virtually instantaneous, thus facilitating the construction of a perceptually equivalent replay condition. We found that three parameters of the Lissajous figure - complexity, line width, and rotational speed - differentially modulated its perceptual dominance durations and transition probabilities, thus providing experimenters with a versatile tool to study the perceptual dynamics of bistable vision. PMID:24718018

Weilnhammer, V A; Ludwig, K; Sterzer, P; Hesselmann, G

2014-05-01

366

Impact of Accuracy, Spatial Availability, and Revisit Time of Satellite-Derived Surface Soil Moisture in a Multiscale Ensemble Data Assimilation System  

Microsoft Academic Search

This study evaluates the sensitivity of a multiscale ensemble assimilation system to different configurations of satellite soil moisture observations, namely the retrieval accuracy, spatial availability, and revisit time. We perform horizontally coupled assimilation experiments where pixels are updated not only by observations at the same location but also all in the study domain. Carrying out sensitivity studies within a multiscale

Ming Pan; Eric F. Wood

2010-01-01

367

"Keeping Close and Spoiling" Revisited: Exploring the Significance of "Home" for Family Relationships and Educational Trajectories in a Marginalised Estate in Urban South Wales  

ERIC Educational Resources Information Center

This paper revisits Diana Leonard's seminal paper "Keeping close and spoiling in a south Wales town", by drawing on one mother and daughter case study. Leonard focused on geographical closeness and the strategies employed by parents to keep their children living at home, rather than sending them to university. In contrast, this…

Mannay, Dawn

2013-01-01

368

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

369

Fractional flow in fractured chalk; a flow and tracer test revisited.  

PubMed

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 (L(4-n)/T and S(2-n)) to conventional transmissivity and storativity (L2/T and dimensionless) for the case where flow dimension, 2

Odling, N E; West, L J; Hartmann, S; Kilpatrick, A

2013-04-01

370

Croll revisited: Why is the northern hemisphere warmer than the southern hemisphere?  

NASA Astrophysics Data System (ADS)

The question of why, in the annual-mean, the northern hemisphere (NH) is warmer than the southern hemisphere (SH) is addressed, revisiting an 1870 paper by James Croll. We first show that ocean is warmer than land in general which, acting alone, would make the SH, with greater ocean fraction, warmer. Croll was aware of this and thought it was caused by greater specific humidity and greenhouse trapping over ocean than over land. However, for any given temperature, it is shown that greenhouse trapping is actually greater over land. Instead, oceans are warmer than land because of the smaller surface albedo. However, hemispheric differences in planetary albedo are negligible because the impact of differences in land-sea fraction are offset by the SH ocean and land reflecting more than their NH counterparts. In the absence of a role for albedo differences it is shown that, in agreement with Croll, northward cross-equatorial ocean heat transport (X-OHT) is critical for the warmer NH. This is examined in a simple box model based on the energy budget of each hemisphere. The hemispheric difference forced by X-OHT is enhanced by the positive water vapor-greenhouse feedback, and is partly compensated by the southward atmospheric energy transport. Due to uncertainties in the ocean data, a range of X-OHT is considered. A X-OHT of larger than 0.5 PW is needed to explain the warmer NH solely by X-OHT. For smaller X-OHT, a larger basic state greenhouse trapping in the NH, conceived as imposed by continental geometry, needs to be imposed. Numerical experiments with a GCM coupled to a slab ocean provide evidence that X-OHT is fundamentally important in determining the hemispheric differences in temperature. Therefore, despite some modifications to his theory, analysis of modern data confirms Croll's 140-year-old theory that the warmer NH is partly because of northward X-OHT.

Kang, Sarah M.; Seager, Richard; Frierson, Dargan M. W.; Liu, Xiaojuan

2014-04-01

371

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

372

Revisiting the polyoxometalate-based late-transition-metal-oxo complexes: the "oxo wall" stands.  

PubMed

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 (17)O and (31)P 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 K(14)[P(2)W(19)O(69)(OH(2))] and "K(10)Na(3)[Pd(IV)(O)(OH)WO(OH(2))(PW(9)O(34))(2)]" and a closer examination of these structures are provided. Also presented are the (17)O NMR spectrum of an (17)O-enriched sample of [PW(11)O(39)](7-) and a careful combined (31)P NMR-titration study of the previously reported "K(7)H(2)[Au(O)(OH(2))P(2)W(20)O(70)(OH(2))(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. PMID:22694272

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; Kögerler, Paul; Hill, Craig L

2012-07-01

373

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

374

Short-term retention of relational memory in amnesia revisited: accurate performance depends on hippocampal integrity  

PubMed Central

Traditionally, it has been proposed that the hippocampus and adjacent medial temporal lobe cortical structures are selectively critical for long-term declarative memory, which entails memory for inter-item and item-context relationships. Whether the hippocampus might also contribute to short-term retention of relational memory representations has remained controversial. In two experiments, we revisit this question by testing memory for relationships among items embedded in scenes using a standard working memory trial structure in which a sample stimulus is followed by a brief delay and the corresponding test stimulus. In each experimental block, eight trials using different exemplars of the same scene were presented. The exemplars contained the same items but with different spatial relationships among them. By repeating the pictures across trials, any potential contributions of item or scene memory to performance were minimized, and relational memory could be assessed more directly than has been done previously. When test displays were presented, participants indicated whether any of the item-location relationships had changed. Then, regardless of their responses (and whether any item did change its location), participants indicated on a forced-choice test, which item might have moved, guessing if necessary. Amnesic patients were impaired on the change detection test, and were frequently unable to specify the change after having reported correctly that a change had taken place. Comparison participants, by contrast, frequently identified the change even when they failed to report the mismatch, an outcome that speaks to the sensitivity of the change specification measure. These results confirm past reports of hippocampal contributions to short-term retention of relational memory representations, and suggest that the role of the hippocampus in memory has more to do with relational memory requirements than the length of a retention interval.

Yee, Lydia T. S.; Hannula, Deborah E.; Tranel, Daniel; Cohen, Neal J.

2014-01-01

375

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

376

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

377

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

378

Disappearing Scales in Carps: Re-Visiting Kirpichnikov's Model on the Genetics of Scale Pattern Formation  

PubMed Central

The body of most fishes is fully covered by scales that typically form tight, partially overlapping rows. While some of the genes controlling the formation and growth of fish scales have been studied, very little is known about the genetic mechanisms regulating scale pattern formation. Although the existence of two genes with two pairs of alleles (S&s and N&n) regulating scale coverage in cyprinids has been predicted by Kirpichnikov and colleagues nearly eighty years ago, their identity was unknown until recently. In 2009, the ‘S’ gene was found to be a paralog of fibroblast growth factor receptor 1, fgfr1a1, while the second gene called ‘N’ has not yet been identified. We re-visited the original model of Kirpichnikov that proposed four major scale pattern types and observed a high degree of variation within the so-called scattered phenotype due to which this group was divided into two sub-types: classical mirror and irregular. We also analyzed the survival rates of offspring groups and found a distinct difference between Asian and European crosses. Whereas nude × nude crosses involving at least one parent of Asian origin or hybrid with Asian parent(s) showed the 25% early lethality predicted by Kirpichnikov (due to the lethality of the NN genotype), those with two Hungarian nude parents did not. We further extended Kirpichnikov's work by correlating changes in phenotype (scale-pattern) to the deformations of fins and losses of pharyngeal teeth. We observed phenotypic changes which were not restricted to nudes, as described by Kirpichnikov, but were also present in mirrors (and presumably in linears as well; not analyzed in detail here). We propose that the gradation of phenotypes observed within the scattered group is caused by a gradually decreasing level of signaling (a dose-dependent effect) probably due to a concerted action of multiple pathways involved in scale formation.

Goh, Chin Heng; Kathiresan, Purushothaman; Nemeth, Sandor; Jeney, Zsigmond; Bercsenyi, Miklos; Orban, Laszlo

2013-01-01

379

Short-term retention of relational memory in amnesia revisited: accurate performance depends on hippocampal integrity.  

PubMed

Traditionally, it has been proposed that the hippocampus and adjacent medial temporal lobe cortical structures are selectively critical for long-term declarative memory, which entails memory for inter-item and item-context relationships. Whether the hippocampus might also contribute to short-term retention of relational memory representations has remained controversial. In two experiments, we revisit this question by testing memory for relationships among items embedded in scenes using a standard working memory trial structure in which a sample stimulus is followed by a brief delay and the corresponding test stimulus. In each experimental block, eight trials using different exemplars of the same scene were presented. The exemplars contained the same items but with different spatial relationships among them. By repeating the pictures across trials, any potential contributions of item or scene memory to performance were minimized, and relational memory could be assessed more directly than has been done previously. When test displays were presented, participants indicated whether any of the item-location relationships had changed. Then, regardless of their responses (and whether any item did change its location), participants indicated on a forced-choice test, which item might have moved, guessing if necessary. Amnesic patients were impaired on the change detection test, and were frequently unable to specify the change after having reported correctly that a change had taken place. Comparison participants, by contrast, frequently identified the change even when they failed to report the mismatch, an outcome that speaks to the sensitivity of the change specification measure. These results confirm past reports of hippocampal contributions to short-term retention of relational memory representations, and suggest that the role of the hippocampus in memory has more to do with relational memory requirements than the length of a retention interval. PMID:24478681

Yee, Lydia T S; Hannula, Deborah E; Tranel, Daniel; Cohen, Neal J

2014-01-01

380

The [C II] 158 Micron Line in Ultraluminous Infrared Galaxies Revisited  

NASA Technical Reports Server (NTRS)

We present a study of the [C II] 157.74 micron fine-structure line in a sample of 15 ultraluminous infrared (IR) galaxies (IR luminosity L(sub IR greater than or equal to 10(exp 12)L.; ULIRGs) using the Long Wavelength Spectrometer (LWS) on the Infrared Space Observatory (ISO). We confirm the observed order of magnitude deficit (compared to normal and starburst galaxies) in the strength of the [C II] line relative to the far-infrared (FIR) dust continuum emission found in our initial report, but here with a sample that is twice as large. This result suggests that the deficit is a general phenomenon affecting 4 out of 5 ULIRGs. We present an analysis using observations of generally acknowledged photodissociation region (PDR) tracers ([C II], [OI] 63 and 145 micron, and FIR continuum emission), which suggests that a high ultraviolet flux G(sub 0) incident on a moderate density n PDR could explain the deficit. However, comparisons with other ULIRG observations, including CO (1-0), [C I] (1-0), and 6.2 micron polycyclic aromatic hydrocarbon (PAH) emission, suggest that high G(sub 0)/n PDRs alone cannot produce a self-consistent solution that is compatible with all of the observations. We propose that non-PDR contributions to the FIR continuum can explain the apparent [C II] deficiency. Here, unusually high G(sub 0) and/ or n physical conditions in ULIRGs as compared to those in normal and starburst galaxies are not required to explain the [C II] deficit. Dust-bounded photoionization regions, which generate much of the FIR emission but do not contribute significant [C II] emission, offer one possible physical origin for this additional non-PDR component. Such environments may also contribute to the observed suppression of FIR fine-structure emission from ionized gas and PAHs, as well as the warmer FIR colors found in ULIRGs. The implications for observations at higher redshifts are also revisited.

Luhman, M. L.; Satyapal, S.; Fischer, J.; Wolfire, M. G.; Sturm, E.; Dudley, C. C.; Lutz, D.; Genzel, R.

2003-01-01

381

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

382

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

383

Critical thickness for plastic relaxation of SiGe on Si(001) revisited  

NASA Astrophysics Data System (ADS)

We have revisited the critical thickness for plastic relaxation hc of SiGe on Si(001). To that end, we have started from prime 200-mm Si(001) wafers and grown (at 20 Torr with SiH2Cl2 and GeH4) various thickness and Ge content SiGe layers in an Epi Centura reduced-pressure-chemical-vapor-deposition chamber. Growth temperature was reduced from 700 °C to 550 °C, as the Ge content increased from 12% to 52%, to minimize surface roughening. X-ray diffraction (XRD) was performed on all samples to determine hc for the various Ge contents probed. Fully strained layers were characterized by: (i) peaks at a constant incidence angle that became narrower and more intense as the thickness increased, and (ii) the presence of numerous thickness fringes on each side of the layers' peaks. Meanwhile, broader, less intense peaks (without thickness fringes) closer to the Si substrate peak were associated with plastically relaxed SiGe layers. Plastic strain relaxation was more gradual and less complete in higher Ge content layers grown at lower temperatures. We then performed haze and atomic force microscopy (AFM) measurements to have wafer and local scale quantifications of the surface roughening, which occurs when exceeding hc. For 12%, 22%, and 32% Ge, the haze and the surface roughness drastically increased for thicknesses greater than hc. For 42% Ge, the haze and the surface roughness were low for layers that had barely begun to relax, and became much larger for layers that were more plastically relaxed. Finally, for 52% Ge, there was a continuous but less pronounced increase of the haze and surface roughness when getting close to or exceeding hc. The critical thickness for plastic relaxation inferred from XRD was, for Ge content 22% and above, approximately two times higher than predicted by the People and Bean theory [Appl. Phys. Lett. 49, 229 (1986)]. However, some of the thickest SiGe 32%-52%, layers, considered fully strained in XRD, were observed by AFM to have a few ``plow'' lines, which are the surface signatures of misfit dislocations.

Hartmann, J. M.; Abbadie, A.; Favier, S.

2011-10-01

384

Strange quark mass from e+e- revisited and present status of light quark masses  

NASA Astrophysics Data System (ADS)

We reconsider the determinations of the strange quark mass ms from e+e- into hadrons data using a new combination of finite energy sum rules (FESR) and revisiting the existing ?-like sum rules by including nonresonant contributions to the spectral functions. To order ?s3 and including the tachyonic gluon mass ?2 contribution, which phenomenologically parametrizes the UV renormalon effect into the perturbative series, we obtain the invariant mass m^s=(119±17)MeV leading to m¯s(2GeV)=(104±15)MeV. Combining this value with the recent and independent phenomenological determinations from some other channels, to order ?s3 and including ?2, we deduce the weighted average m¯s(2GeV)=(96.1±4.8)MeV. The positivity of the spectral functions in the (pseudo)scalar (resp. vector) channels leads to the lower (resp. upper) bounds of m¯s(2GeV): (71±4)MeV?m¯s(2GeV)?(151±14)MeV, to order ?s3. Using the chiral perturbation theory (ChPT) mass ratio r3?2ms/(mu+md)=24.2±1.5, and the average value of ms, we deduce (m¯u+m¯d)(2GeV)=(7.9±0.6)MeV, consistent with the pion sum rule result, which, combined with the ChPT value for mu/md, gives m¯d(2GeV)=(5.1±0.4)MeV and m¯u(2GeV)=(2.8±0.2)MeV. Finally, using (m¯u+m¯d) from the pion sum rule and the average value of m¯s (without the pion sum rule), the method gives r3=23.5±5.8, in perfect agreement with the ChPT ratio, indicating the self-consistency of the sum rule results. Using the value m¯b(m¯b)=(4.23±0.06)GeV, we also obtain the scale-independent mass ratio mb/ms=50±3, which is useful for model-buildings. Absolute values of the light quark masses from QCD spectral sum rules reported in this paper are the most accurate determinations to date.

Narison, Stephan

2006-08-01

385

Non-24-Hour Disorder in Blind Individuals Revisited: Variability and the Influence of Environmental Time Cues  

PubMed Central

Study Objectives: To assess the interindividual and intraindividual variability in the circadian rhythms of blind individuals with non-24-h disorder and to quantify the influence of environmental time cues in blind subjects lacking entrainment (non-24-h individuals or N-24s). Design: An observational study of 21 N-24s (11 females and 10 males, age 9-78 years) who kept a sleep/wake schedule of their choosing. Circadian phase was determined using the melatonin onset (MO) from plasma or saliva samples that were collected every 2 weeks. Melatonin concentrations were measured by radioimmunoassay. A total of 469 MO assessments were conducted over 5,536 days of study. The rate of drift of circadian phase was calculated using a series of MOs (total number of hours the MO drifted divided by the total number of days studied). Stability of the rest/activity rhythm was calculated using chi-squared periodogram analysis of wrist actigraphy data in 19 subjects. Setting: Academic medical center. Participants: Paid volunteers. Interventions: N/A. Measurements and Results: Subjects lacked entrainment such that circadian phase drifted an average (± standard deviation) of 0.39 ± 0.29 h later per day; however, there was notable intersubject and intrasubject variability in the rate of drift including relative coordination and periods of transient entrainment during which there was little to no drift in the circadian phase. A regular, reproducible, and significant oscillation in the rate of drift was detected in 14 of the 21 subjects. A significant non-24-h rest/activity rhythm was detected in 18 of 19 subjects. There was a strong correlation (r = 0.793, P = 0.0001) between the non-24-h rest/activity rhythm and the rate of drift of the circadian phase. Conclusions: Most N-24s are influenced by unidentified environmental time cues and the non-entrained biological clock in such N-24s is reflected in their rest/activity rhythms. These findings may have diagnostic and treatment implications: this disorder might be diagnosed with actigraphy alone, relative coordination and transient entrainment may result in misdiagnosis and responsiveness to environmental time cues may influence treatment success with oral melatonin. Citation: Emens JS; Laurie AL; Songer JB; Lewy AJ. Non-24-hour disorder in blind individuals revisited: variability and the influence of environmental time cues. SLEEP 2013;36(7):1091-1100.

Emens, Jonathan S.; Laurie, Amber L.; Songer, Jeannie B.; Lewy, Alfred J.

2013-01-01

386

The time course of photoinactivation of photosystem II in leaves revisited.  

PubMed

Since photosystem II (PS II) performs the demanding function of water oxidation using light energy, it is susceptible to photoinactivation during photosynthesis. The time course of photoinactivation of PS II yields useful information about the process. Depending on how PS II function is assayed, however, the time course seems to differ. Here, we revisit this problem by using two additional assays: (1) the quantum yield of oxygen evolution in limiting, continuous light and (2) the flash-induced cumulative delivery of PS II electrons to the oxidized primary donor (P700(+)) in PS I measured as a 'P700 kinetics area'. The P700 kinetics area is based on the fact that the two photosystems function in series: when P700 is completely photo-oxidized by a flash added to continuous far-red light, electrons delivered from PS II to PS I by the flash tend to re-reduce P700(+) transiently to an extent depending on the PS II functionality, while the far-red light photo-oxidizes P700 back to the steady-state concentration. The quantum yield of oxygen evolution in limiting, continuous light indeed decreased in a way that deviated from a single-negative exponential. However, measurement of the quantum yield of oxygen in limiting light may be complicated by changes in mitochondrial respiration between darkness and limiting light. Similarly, an assay based on chlorophyll fluorescence may be complicated by the varying depth in leaf tissue from which the signal is detected after progressive photoinactivation of PS II. On the other hand, the P700 kinetics area appears to be a reasonable assay, which is a measure of functional PS II in the whole leaf tissue and independent of changes in mitochondrial respiration. The P700 kinetics area decreased in a single-negative exponential fashion during progressive photoinactivation of PS II in a number of plant species, at least at functional PS II contents ?6 % of the initial value, in agreement with the conclusion of Sarvikas et al. (Photosynth Res 103:7-17, 2010). That is, the single-negative-exponential time course does not provide evidence for photoprotection of functional PS II complexes by photoinactivated, connected neighbours. PMID:22644475

Kou, Jiancun; Oguchi, Riichi; Fan, Da-Yong; Chow, Wah Soon

2012-09-01

387

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

388

Ups and downs of Viagra: revisiting ototoxicity in the mouse model.  

PubMed

Sildenafil citrate (Viagra), a phosphodiesterase 5 inhibitor (PDE5i), is a commonly prescribed drug for erectile dysfunction. Since the introduction of Viagra in 1997, several case reports have linked Viagra to sudden sensorineural hearing loss. However, these studies are not well controlled for confounding factors, such as age and noise-induced hearing loss and none of these reports are based on prospective double-blind studies. Further, animal studies report contradictory data. For example, one study (2008) reported hearing loss in rats after long-term and high-dose exposure to sildenafil citrate. The other study (2012) showed vardenafil, another formulation of PDE5i, to be protective against noise-induced hearing loss in mice and rats. Whether or not clinically relevant doses of sildenafil citrate cause hearing loss in normal subjects (animals or humans) is controversial. One possibility is that PDE5i exacerbates age-related susceptibility to hearing loss in adults. Therefore, we tested sildenafil citrate in C57BL/6J, a strain of mice that displays increased susceptibility to age-related hearing loss, and compared the results to those obtained from the FVB/N, a strain of mice with no predisposition to hearing loss. Six-week-old mice were injected with the maximum tolerated dose of sildenafil citrate (10 mg/kg/day) or saline for 30 days. Auditory brainstem responses (ABRs) were recorded pre- and post injection time points to assess hearing loss. Entry of sildenafil citrate in the mouse cochlea was confirmed by qRT-PCR analysis of a downstream target of the cGMP-PKG cascade. ABR data indicated no statistically significant difference in hearing between treated and untreated mice in both backgrounds. Results show that the maximum tolerated dose of sildenafil citrate administered daily for 4 weeks does not affect hearing in the mouse. Our study gives no indication that Viagra will negatively impact hearing and it emphasizes the need to revisit the issue of Viagra related ototoxicity in humans. PMID:24244454

Au, Adrian; Stuyt, John Gerka; Chen, Daniel; Alagramam, Kumar

2013-01-01

389

Clostridium sticklandii, a specialist in amino acid degradation:revisiting its metabolism through its genome sequence  

PubMed Central

Background Clostridium sticklandii belongs to a cluster of non-pathogenic proteolytic clostridia which utilize amino acids as carbon and energy sources. Isolated by T.C. Stadtman in 1954, it has been generally regarded as a "gold mine" for novel biochemical reactions and is used as a model organism for studying metabolic aspects such as the Stickland reaction, coenzyme-B12- and selenium-dependent reactions of amino acids. With the goal of revisiting its carbon, nitrogen, and energy metabolism, and comparing studies with other clostridia, its genome has been sequenced and analyzed. Results C. sticklandii is one of the best biochemically studied proteolytic clostridial species. Useful additional information has been obtained from the sequencing and annotation of its genome, which is presented in this paper. Besides, experimental procedures reveal that C. sticklandii degrades amino acids in a preferential and sequential way. The organism prefers threonine, arginine, serine, cysteine, proline, and glycine, whereas glutamate, aspartate and alanine are excreted. Energy conservation is primarily obtained by substrate-level phosphorylation in fermentative pathways. The reactions catalyzed by different ferredoxin oxidoreductases and the exergonic NADH-dependent reduction of crotonyl-CoA point to a possible chemiosmotic energy conservation via the Rnf complex. C. sticklandii possesses both the F-type and V-type ATPases. The discovery of an as yet unrecognized selenoprotein in the D-proline reductase operon suggests a more detailed mechanism for NADH-dependent D-proline reduction. A rather unusual metabolic feature is the presence of genes for all the enzymes involved in two different CO2-fixation pathways: C. sticklandii harbours both the glycine synthase/glycine reductase and the Wood-Ljungdahl pathways. This unusual pathway combination has retrospectively been observed in only four other sequenced microorganisms. Conclusions Analysis of the C. sticklandii genome and additional experimental procedures have improved our understanding of anaerobic amino acid degradation. Several specific metabolic features have been detected, some of which are very unusual for anaerobic fermenting bacteria. Comparative genomics has provided the opportunity to study the lifestyle of pathogenic and non-pathogenic clostridial species as well as to elucidate the difference in metabolic features between clostridia and other anaerobes.

2010-01-01

390

Revisiting the Impact of Atmospheric Refraction on VIMOS-MOS Observations: Beyond the Two-hour Angle Rule  

NASA Astrophysics Data System (ADS)

Multi-object spectroscopic (MOS) observations with VIMOS have traditionally been limited to a narrow two-hour range from the meridian to minimise slit losses caused by atmospheric dispersion and differential refraction. We revisit the impact of these effects on the quality of VIMOS-MOS spectra through extensive simulations of slit losses. We show that MOS observations can be effectively extended to plus/minus three hours from the meridian for fields with zenith angles smaller than 20 degrees at culmination — provided a nonstandard rotator offset angle of 0 degrees is used. The increase in target observability will enhance the efficiency of operations, and hasten the completion of programmes — a particularly relevant aspect for the forthcoming spectroscopic public surveys with VIMOS.

Sánchez-Janssen, R.; Selman, F.; Mieske, S.; Bristow, P.; Hammersley, P.; Hilker, M.; Rejkuba, M.; Wolff, B.

2013-12-01

391

Multiple target tracking with symmetric measurement equations revisited: unscented Kalman filters, particle filters, and Taylor series expansions  

NASA Astrophysics Data System (ADS)

The symmetric measurement equation (SME) approach to multiple target tracking is revisited using unscented Kalman and particle filters. The unscented Kalman filter (UKF) promises more accurate approximation of nonlinearities and simpler implementation of the SME approach than the EKF. The particle filter implementation offers the ability to explore the limits of the SME approach. In the first portion of this paper, experiences with SME for tracking one-dimensional motion are reviewed. The second portion of this paper discusses the challenges that arise when using the SME approach to track two-dimensional motion and introduces a new set of two-dimensional SME equations. Finally, Taylor series expansions are used to explore differences between Kalman filter-SME pairings. Using the Taylor series representation, we show how the choice of SME formulation affects the representation, and consequently approximation, of uncertainty in the Kalman filters.

Leven, William F.; Lanterman, Aaron D.

2005-05-01

392

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

393

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

394

Revisiting Marey’s Applications of Scientific Moving Image Technologies in the Context of Bergson’s Philosophy: Audio-Visual Mediation and the Experience of Time  

Microsoft Academic Search

This paper revisits some early applications of audio-visual imaging technologies used in physiology in a dialogue with reflections\\u000a on Henri Bergson’s philosophy. It focuses on the aspects of time and memory in relation to spatial representations of movement\\u000a measurements and critically discusses them from the perspective of the observing participant and the public exhibitions of\\u000a scientific films. Departing from an

Martha Blassnigg

2010-01-01

395

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

396

Soft bottom macrobenthic communities of North Biscay revisited: Long-term evolution under fisheries-climate forcing  

NASA Astrophysics Data System (ADS)

Thirty-five years after the first description of the benthic community and sediments of the North Bay of Biscay continental shelf (80-200 m depth in the "Grande Vasière" region) by Glémarec (personal communication), the sampling stations were revisited to provide a new reference on the status of the macrozoobenthic communities to help our understanding and management of fisheries that are highly developed in this area. Results showed that large modifications occurred in the communities and sediments of the central part of the "Grande Vasière", while these modifications remained moderate in the surroundings on the outer continental shelf. Revisited, macrobenthic communities differed greatly from those recorded in the 1960s, and were less numerous and more homogeneous. The dominant species which characterized the communities and sub-communities had also changed. The main factor that can explain these differences is the granulometry of the sediments which has shown large changes: a strong decrease in the mud fraction and increase in the fine sand fraction. These sedimentary changes should be linked with human activities: increase in bottom trawling effort that induces the resuspension of fine mud particles and the homogenization of sediments over large areas, and decrease in terrigenous particulate fluxes due to anthropic activities on the shoreline and in coastal waters. Effects of global climatic change on the observed evolution remain low, even if some species common in the south of the Bay of Biscay in the 1960s but rare or absent in the north, had increased in density and spread to the north. Trawling activities are probably the main force driving benthic community evolution in the North Bay of Biscay both through direct action on the fauna (inhibition and facilitation processes) and indirect action by modifying sediment characteristics.

Hily, C.; Le Loc'h, F.; Grall, J.; Glémarec, M.

2008-06-01

397

Mid-Miocene Silicic Volcanism of the Three Fingers - Mahogany Mountain Area, SE Oregon - Revisited  

NASA Astrophysics Data System (ADS)

Earlier work identified two adjacent caldera systems, the Mahogany Mountain and Three Fingers calderas as the centerpiece of voluminous rhyolitic volcanism on the eastern margin of the Oregon-Idaho graben during the mid-Miocene. Silicic volcanism of Three Fingers-Mahogany Mtn. area is part of the Lake Owyhee volcanic field, Oregon and belongs to widespread rhyolites associated with the Columbia River Basalt province. Here we revisit field evidence and establish relationships between intra-caldera units of Three Fingers and Mahogany Mtn. calderas, and their outflow facies, the tuffs of Spring Creek and Leslie Gulch. In addition, we assess the distribution of entrained mafic clasts and their often anomalously high, nearly ore-grade concentrations of rare earth elements (REE). Previous mapping identified two groups of intra-caldera rhyolite units: 1) intra-caldera tuffs of Spring Creek and Leslie Gulch and 2) younger rhyolite lavas (Trp) within Three Fingers Caldera and cross-cutting rhyolite dikes within the core of Mahogany Mtn. Caldera. Our mapping determines that devitrified Trp of Three Fingers area is equivalent to surrounding often glassy, pumiceous to dense or brecciated rhyolite flows mapped before as intra-caldera tuff of Spring Creek, and all are compositionally indistinguishable from cross-cutting dikes within Mahogany Mtn. Reinterpreted rhyolites of Three Fingers Caldera lack vitroclastic textures and are geochemically distinct from outflow tuff of Spring Creek which in turn can be distinguished from the tuff of Leslie Gulch. Outflow tuff of Spring Creek is Fe-rich, low silica rhyolite (~74 wt.% SiO2, 3 wt.% FeO, ~1600 ppm Ba) as compared to less Fe rich, high-silica rhyolite (~77 wt.% SiO2, 2 wt.% FeO, ~200 ppm Ba) of intra-caldera units. Outflow tuff of Leslie Gulch is also high-silica rhyolite but Ba rich (~1500 ppm). We interpret the investigated Three Fingers area as a rhyolite dome field, erupting subsequent to caldera collapse. There, abundant post-collapse rhyolite volcanism resulted in a complex stratigraphic overlap of rhyolite flows and clastic debris issued from closely-spaced domes. The predominance of high-standing dome interiors reflects the more resistant nature of dense devitrified rhyolite as compared to pumiceous, glassy, or brecciated rhyolite. New 40Ar/39Ar data reveal intra-caldera rhyolites and outflow tuff of Spring Creek to be indistinguishable at 15.64 × 0.08 Ma yet field evidence indicates eruption of post-caldera rhyolites occurred after sedimentation within the caldera. The existence of two outflow tuff units suggests two collapse structures and ages indicate the Mahogany Mtn. Caldera preceded the younger rhyolites by ~200,000 years. Mafic clasts present in dense glassy or porous intra-caldera rhyolites of Three Fingers are reworked fragments of preexisting lava flows that were entrained by subsequent eruptions. Ore-grade REE enrichment of over 2400 ppm Nd in these clasts is likely facilitated by mobilization of REE from earlier rhyolites during renewed rhyolite magmatism and subsequent deposition.

Marcy, P.; Streck, M. J.; Ferns, M.

2013-12-01

398

REVISITING THE SCALE LENGTH-{mu}{sub 0} PLANE AND THE FREEMAN LAW IN THE LOCAL UNIVERSE  

SciTech Connect

We have used Virtual Observatory technology to analyze the disk scale length r{sub d} and central surface brightness {mu}{sub 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 ({mu}{sub 0}) = 20.2 {+-} 0.7 mag arcsec{sup -2}. We confirm that late-type spirals populate the lower left corner of the r{sub d} -{mu}{sub 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 {mu}{sub 0} in bright disk galaxies with r {sub 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 [Stockholm Observatory, Department of Astronomy, Stockholm University, AlbaNova Center, 106 91 Stockholm (Sweden); Oskar Klein Centre for Cosmoparticle Physics, Stockholm University, 106 91 Stockholm (Sweden)

2010-10-10

399

TOPICAL REVIEW: Growth modes of Fe(110) revisited: a contribution of self-assembly to magnetic materials  

NASA Astrophysics Data System (ADS)

We have revisited the epitaxial growth modes of Fe on W(110) and Mo(110), and propose an overview or our contribution to the field. We show that the Stranski-Krastanov growth mode, acknowledged for a long time in these systems, is in fact characterized by a bimodal distribution of islands for a growth temperature in the range ~250-700 °C. We observe firstly compact islands whose shape is determined by Wulff-Kaischev's theorem, and secondly thin and flat islands that display a preferred height, i.e. are independent of nominal thickness and deposition procedures (1.4 nm for Mo, and 5.5 nm for W on the average). We used this effect to fabricate self-organized arrays of nanometres-thick stripes by step decoration. Self-assembled nanoties are also obtained for nucleation of the flat islands on Mo at fairly high temperature, i.e. ~800 °C. Finally, using interfacial layers and solid solutions we separate two effects on the preferred height, first that of the interfacial energy, and second that of the continuously varying lattice parameter of the growth surface.

Fruchart, O.; Jubert, P. O.; Eleoui, M.; Cheynis, F.; Borca, B.; David, P.; Santonacci, V.; Liénard, A.; Hasegawa, M.; Meyer, C.

2007-02-01

400

'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

401

'There and back again': revisiting the pathophysiological roles of human endogenous retroviruses in the post-genomic era.  

PubMed

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. PMID:23938753

Magiorkinis, Gkikas; Belshaw, Robert; Katzourakis, Aris

2013-09-19

402

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

ERIC Educational Resources Information Center

Recent evidence points to white-matter abnormalities as a key factor in autism physiopathology. Using Diffusion Tensor Imaging, we studied white-matter structural properties in a convenience sample of twenty-two subjects with low-functioning autism exposed to long-term augmentative and alternative communication, combined with sessions of cognitive…

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

2012-01-01

403

Repeat topography surveys of geomorphic changes using digital surface models deriving from Formosat-2 daily revisit stereo pair with very narrow baseline  

NASA Astrophysics Data System (ADS)

Repeat topography surveys provides a geometrically-corrected frame with relief information, which is crucial for studying geomorphic changes after a major slope hazard, such as the debris flow or landslides. The successful operation of Formosat-2 has 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, as each accessible scene can be systematically observed from the same angle under similar illumination conditions. These characteristics make Formosat-2 an ideal satellite for site surveillance, and its images have been successfully applied in environmental monitoring, hazard assessment, orthomap generation, rapidly responding to a global disaster event, and land use management. The attempt of using a Formosat-2 stereo pair to generate a DSM, however, has not been very successful up-to-date. Ironically, it is mainly due to the characteristics of daily-revisit orbit as well. According to the parallax equation, to obtain an accurate height estimation requires a high disparity precision from the stereo pair. The most convenient approach is to maximize the baseline B or the baseline/height (B/H) ratio to a preferred range 0.6 to 1. It is not feasible, however, to acquire an across-track stereo pair with that range of baseline from the daily-revisit orbit using Formosat-2. Even taking the orbit drifting into consideration, it would take a few months to achieve a B/H ratio of approximately 0.15 across track. Another approach is to acquire an along-track stereo pair. But for the mountainous areas, such as the central mountain areas, in Taiwan, the shaded effect and geometrically distortion are apparent. This prohibits any attempt to employ the automatic image matching technique to generate a DSM based on the disparities retrieved from Frmosat-2 along-track stereo pair directly. Phase correlation is operated in the frequency-domain, which enables the relative translative offset between two similar images to be rapidly estimated. To meet the requirements in remote sensing and biomedical imaging, the technology of phase correlation has been extended to the sub-pixel level. Liu and Yan (2008) developed a robust phase correlation model using the based feature matching for image co-registration and DEM generation. Considering the fact that the Formosat-2 consecutive images are intrinsically stereo pairs with very narrow baselines, this innovative stereo-matching algorithm based on SPPC technique is employed to process Formosat-2 daily revisit stereo pairs with very narrow baselines. The detailed accuracy and efficiency analysis is investigated for the study area, Namasha, Kaohsiung, using the 50cm resolution aerial photo and the 2m resolution DEM derived from airborne LiDAR data. The archive of Formosat-2 images in Taiwan area collected from 2005 to 2012 was screened out, with the intention to select the consecutive pairs of those areas where major slope disasters occurred in the past eight years. This research encourages the repeated topography surveys of geomorphic changes using digital surface models deriving from Formosat-2 daily revisit stereo pair with very narrow baseline.

Liu, C.; Wen, H.; Liu, J.; Ko, M.; Yan, H.; Chang, L.

2012-12-01

404

Social cognition: empirical contribution. The developmental building blocks of psychopathic traits: revisiting the role of theory of mind.  

PubMed

In the context of personality disorder development, theories of typical and atypical development both emphasize social cognition as an important building block for personality development. Prior claims of intact theory of mind (ToM) abilities in psychopathic individuals have relied upon a narrow conception of ToM as equivalent to "cognitive empathy." In this article, the authors make use of a broader conception of ToM comprising top-down and bottom-up processing, as well as the fractionation of ToM in terms of reduced or excessive ToM function, to examine relationships between ToM and psychopathic traits. A total of 342 adolescents (ages 12-17; Mage 15.39; SD = 1.45; 61.5% females) completed the Movie Assessment for Social Cognition (Dziobek, Fleck, Kalbe, et al., 2006) and the Child Eyes Test (Baron-Cohen, Wheelwright, Hill, Raste, & Plumb, 2001) in addition to three measures of psychopathic traits. Results demonstrated unique relations between the affective components of psychopathy (callous-unemotional traits [CU traits]) and impairment in both top-down and bottom-up ToM. In addition, excessive ToM related to affective components of psychopathy, while reduced or no ToM related to behavioral components of psychopathy. In mediational analyses, bottom-up ToM was shown to be necessary for top-town ToM in its relation with CU traits. Taken together, these results from the study lend support to revisiting the link between ToM and psychopathy. PMID:24344889

Sharp, Carla; Vanwoerden, Salome

2014-02-01

405

Infectious Speciation Revisited: Impact of Symbiont-Depletion on Female Fitness and Mating Behavior of Drosophila paulistorum  

PubMed Central

The neotropical Drosophila paulistorum superspecies, consisting of at least six geographically overlapping but reproductively isolated semispecies, has been the object of extensive research since at least 1955, when it was initially trapped mid-evolution in flagrant statu nascendi. In this classic system females express strong premating isolation patterns against mates belonging to any other semispecies, and yet uncharacterized microbial reproductive tract symbionts were described triggering hybrid inviability and male sterility. Based on theoretical models and limited experimental data, prime candidates fostering symbiont-driven speciation in arthropods are intracellular bacteria belonging to the genus Wolbachia. They are maternally inherited symbionts of many arthropods capable of manipulating host reproductive biology for their own benefits. However, it is an ongoing debate as to whether or not reproductive symbionts are capable of driving host speciation in nature and if so, to what extent. Here we have reevaluated this classic case of infectious speciation by means of present day molecular approaches and artificial symbiont depletion experiments. We have isolated the ?-proteobacteria Wolbachia as the maternally transmitted core endosymbionts of all D. paulistorum semispecies that have coevolved towards obligate mutualism with their respective native hosts. In hybrids, however, these mutualists transform into pathogens by overreplication causing embryonic inviability and male sterility. We show that experimental reduction in native Wolbachia titer causes alterations in sex ratio, fecundity, and mate discrimination. Our results indicate that formerly designated Mycoplasma-like organisms are most likely Wolbachia that have evolved by becoming essential mutualistic symbionts in their respective natural hosts; they have the potential to trigger pre- and postmating isolation. Furthermore, in light of our new findings, we revisit the concept of infectious speciation and discuss potential mechanisms that can restrict or promote symbiont-induced speciation at post- and prezygotic levels in nature and under artificial laboratory conditions.

Miller, Wolfgang J.; Ehrman, Lee; Schneider, Daniela

2010-01-01

406

Revisiting the contribution of negative charges on the chaperonin cage wall to the acceleration of protein folding  

PubMed Central

Chaperonin GroEL mediates the folding of protein encapsulated in a GroES-sealed cavity (cage). Recently, a critical role of negative charge clusters on the cage wall in folding acceleration was proposed based on experiments using GroEL single-ring (SR) mutants SR1 and SRKKK2 [Tang YC, et al. (2006) Cell 125:903–914; Chakraborty K, et al. (2010) Cell 142:112–122]. Here, we revisited these experiments and discovered several inconsistencies. (i) SR1 was assumed to bind to GroES stably and to mediate single-round folding in the cage. However, we show that SR1 repeats multiple turnovers of GroES release/binding coupled with ATP hydrolysis. (ii) Although the slow folding observed for a double-mutant of maltose binding protein (DMMBP) by SRKKK2 was attributed to mutations that neutralize negative charges on the cage wall, we found that the majority of DMMBP escape from SRKKK2 and undergo spontaneous folding in the bulk medium. (iii) An osmolyte, trimethylamine N-oxide, was reported to accelerate SRKKK2-mediated folding of DMMBP by mimicking the effect of cage-wall negative charges of WT GroEL and ordering the water structure to promote protein compaction. However, we demonstrate that in-cage folding by SRKKK2 is unaffected by trimethylamine N-oxide. (iv) Although it was reported that SRKKK2 lost the ability to assist the folding of ribulose-1,5-bisphosphate carboxylase/oxygenase, we found that SRKKK2 retains this ability. Our results argue against the role of the negative charges on the cage wall of GroEL in protein folding. Thus, in chaperonin studies, folding kinetics need to be determined from the fraction of the real in-cage folding.

Motojima, Fumihiro; Motojima-Miyazaki, Yuko; Yoshida, Masasuke

2012-01-01

407

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 , at least within its 1 ? ranges. In the second scenario where the NP contributes also to the absorptive part ?_{{{12}}}^s via tree-level Z'-induced b ? coverline c s operators, we find that, with the constraints from ? M s , ? s and the indirect CP asymmetry in {{overline B }_d} ? J/?K S taken into account, the present measured 1 ? experimental ranges for a_{{fs}}^s could not be reproduced too. Thus, such a specific Z' model with our specific assumptions could not simultaneously reconcile all the present data on B_s^0 - overline B_s^0 mixing. Future improved measurements from the LHCb and the proposed superB experiments, especially of the flavour-specific CP asymmetries, are expected to shed light on the issue.

Li, Xin-Qiang; Li, Yan-Min; Lu, Gong-Ru; Su, Fang

2012-05-01

408

Effect of the air hammer on the hands of stonecutters. The limestone quarries of Bedford, Indiana, revisited.  

PubMed Central

In the limestone quarries of Indiana, USA, pneumatic percussive hammers replaced the mallet and hammer around 1900. By 1917 the air hammer was being used exclusively for periods of eight to ten hours a shift. In 1918 Alice Hamilton investigated an unusual "disease" in these stonecutters of Bedford, Indiana, who complained of "attacks of numbness and blanching of the fingers coming on suddenly under the influence of cold and then disappearing." The prevalence of vibration induced white finger (VWF) found in this population of 38 stonecutters was 89%, with decreased light touch, pain, and temperature appreciation in advanced cases. In 1978 a VWF research team revisited these limestone quarries. During the 60 year interval the stonecutting industry had contracted from 4000 workers in 40 quarries in 1918 to 3-400 in 10 quarries in 1978, with only 50 employees remaining in the Bedford area. In a population of 30 stonecutters the prevalence of VWF in 1978 was 80%, with similar sensory loss in light touch, pain, and temperature appreciation. Between 1918 and 1978 no change had taken place in the design of the air hammers used for stonecutting. Vibration levels of 4859 metres/s2 on the chisel, and 2010 metres/s2 on the barrel were measured over a frequency range 6.3 to 1000 Hz. The fundamental frequency was 75 Hz. These measured vibration levels are outside the ISO/DIS/5349 (1979) recommended limits for human exposure to vibration transmitted to the hand. The VWF data presented in this paper, and those originally reported by Hamilton in 1918, call for an immediate redesign of stonecutting pneumatic hammers in order to remove one cause of Raynaud's phenomenon of occupational origin. Images

Taylor, W; Wasserman, D; Behrens, V; Reynolds, D; Samueloff, S

1984-01-01

409

Eurotatorian paraphyly: Revisiting phylogenetic relationships based on the complete mitochondrial genome sequence of Rotaria rotatoria (Bdelloidea: Rotifera: Syndermata)  

PubMed Central

Background The Syndermata (Rotifera+Acanthocephala) is one of the best model systems for studying the evolutionary origins and persistence of different life styles because it contains a series of lineage-specific life histories: Monogononta (cyclic parthenogenetic and free-living), Bdelloidea (entirely parthenogenetic and mostly benthic dweller), Seisonidea (exclusively bisexual and epizoic or ectoparasitic), and Acanthocephala (sexual and obligatory endoparasitic). Providing phylogenetic resolution to the question of Eurotatoria (Monogononta and Bdelloidea) monophyly versus paraphyly is a key factor for better understanding the evolution of different life styles, yet this matter is not clearly resolved. In this study, we revisited this issue based on comparative analysis of complete mitochondrial genome information for major groups of the Syndermata. Results We determined the first complete mitochondrial genome sequences (15,319 bp) of a bdelloid rotifer, Rotaria rotatoria. In order to examine the validity of Eurotatoria (Monogononta and Bdelloidea) monophyly/paraphyly, we performed phylogenetic analysis of amino acid sequences for eleven protein-coding genes sampled from a wide variety of bilaterian representatives. The resulting mitochondrial genome trees, inferred using different algorithms, consistently failed to recover Monogononta and Bdelloidea as monophyletic, but instead identified them as a paraphyletic assemblage. Bdelloidea (as represented by R. rotatoria) shares most common ancestry with Acanthocephala (as represented by L. thecatus) rather than with monogonont B. plicatilis, the other representative of Eurotatoria. Conclusion Comparisons of inferred amino acid sequence and gene arrangement patterns with those of other metazoan mtDNAs (including those of acanthocephalan L. thecatus and monogonont B. plicatilis) support the hypothesis that Bdelloidea shares most common ancestry with Acanthocephala rather than with Monogononta. From this finding, we suggest that the obligatory asexuality of bdelloideans may have secondarily derived from some other preexisting condition in earlier lineage of rotifers. Providing a more complete assessment of phylogenetic relationships and inferring patterns of evolution of different types of life styles among Syndermata awaits comparisons requiring mitochondrial genome sequencing of Seisonidea.

2009-01-01

410

Unexpected extensions of non-small-cell lung cancer diagnosed during surgery: revisiting exploratory thoracotomies and incomplete resections  

PubMed Central

OBJECTIVES Only patients with a complete resection of non-small-cell lung cancer (NSCLC) may expect long-term survival. Despite the recent progress in imaging and induction therapy, a thoracotomy may remain exploratory or with incomplete resection (R2). Our purpose was to revisit these situations. METHODS A total of 5305 patients who underwent surgery for NSCLC between 1980 and 2009 were reviewed. We compared the epidemiology, pathology, causes and prognosis characteristics of exploratory thoracotomy (ET) and R2 resections. RESULTS ET and R2 resections were observed in 223 (4%) and 197 (4%) patients, respectively. The frequency of ET decreased with time, while the frequency of R2 resection remained almost stable. The indications for ET and R2 resections were not significantly different. In comparison with ET, R2 resections were characterized by a significantly higher frequency of induction therapy (22 vs 17%, P < 10?3), adenocarcinomas (49 vs 15%, P < 10?6), T1–T2 (53 vs 29%, P < 10?6) and N0–N1 extension (67 vs 42%, P = 10?6). R2 resections were also characterized by a higher rate of postoperative complications (19.1 vs 9.9%, P = 0.014), with no significant difference in postoperative mortality (6.9 vs 4.9%, P = non significant). R2 resections resulted in a higher 5-year survival compared with ET (11.1 vs 1.2%, P = 10?3). There was no long-term survivor after ET, except during the last decade. CONCLUSIONS ET and R2 remain unavoidable. In comparison with ET, R2 resection is associated with a higher rate of postoperative complications, but a higher long-term survival.

Foucault, Christophe; Mordant, Pierre; Grand, Bertrand; Achour, Karima; Arame, Alex; Dujon, Antoine; Le Pimpec Barthes, Francoise; Riquet, Marc

2013-01-01

411

Embryonic rat vascular smooth muscle cells revisited - a model for neonatal, neointimal SMC or differentiated vascular stem cells?  

PubMed Central

Background The A10 and A7r5 cell lines derived from the thoracic aorta of embryonic rat are widely used as models of non-differentiated, neonatal and neointimal vascular smooth muscle cells in culture. The recent discovery of resident multipotent vascular stem cells within the vessel wall has necessitated the identity and origin of these vascular cells be revisited. In this context, we examined A10 and A7r5 cell lines to establish the similarities and differences between these cell lines and multipotent vascular stem cells isolated from adult rat aortas by determining their differentiation state, stem cell marker expression and their multipotency potential in vitro. Methods Vascular smooth muscle cell differentiation markers (alpha-actin, myosin heavy chain, calponin) and stem cell marker expression (Sox10, Sox17 and S100?) were assessed using immunocytochemistry, confocal microscopy, FACS analysis and real-time quantitative PCR. Results Both A10 and A7r5 expressed vascular smooth muscle differentiation, markers, smooth muscle alpha?-?actin, smooth muscle myosin heavy chain and calponin. In parallel analysis, multipotent vascular stem cells isolated from rat aortic explants were immunocytochemically myosin heavy chain negative but positive for the neural stem cell markers Sox10+, a neural crest marker, Sox17+ the endoderm marker, and the glia marker, S100?+. This multipotent vascular stem cell marker profile was detected in both embryonic vascular cell lines in addition to the adventitial progenitor stem cell marker, stem cell antigen-1, Sca1+. Serum deprivation resulted in a significant increase in stem cell and smooth muscle cell differentiation marker expression, when compared to serum treated cells. Both cell types exhibited weak multipotency following adipocyte inductive stimulation. Moreover, Notch signaling blockade following ?-secretase inhibition with DAPT enhanced the expression of both vascular smooth muscle and stem cell markers. Conclusions We conclude that A10 and A7r5 cells share similar neural stem cell markers to both multipotent vascular stem cells and adventitial progenitors that are indicative of neointimal stem-derived smooth muscle cells. This may have important implications for their use in examining vascular contractile and proliferative phenotypes in vitro.

2014-01-01

412

Thermal expansion of the high-7c superconductors REBa2Cu3O7 (RE = Y, Dy) revisited at low temperatures  

NASA Astrophysics Data System (ADS)

The linear thermal expansion coefficient ?(T) of two high-Tc superconductors, YBa2Cu3O7 and DyBa2Cu3O7 has been revisited in the 4.5-80K temperature range. The X-ray diffraction analysis and microstructural characterization using scanning electron microscopy confirm an orthorhombic single phase with an average of the grain size of about 20 ?m for both polycrystalline samples. In the case of the Dy compound, a small magnetic excess superimposed to the high phonon contribution is observed in the T3 term, whereas no anomaly is detected below 40K. The deduced magnetic contribution ?m(T) which increases monotonically with rising temperature is attributed to the CF interactions induced by the 4f electric quadrupole moment of the Dy Kramers ions. A discussion and a comparison with respect to the previous experimental and theoretical works are presented.

Lahoubi, M.

2014-05-01

413

Revisiting regional flood frequency analysis in Slovakia: the region-of-influence method vs. traditional regional approaches  

NASA Astrophysics Data System (ADS)

During the last 10-15 years, the Slovak hydrologists and water resources managers have been devoting considerable efforts to develop statistical tools for modelling probabilities of flood occurrence in a regional context. Initially, these models followed concepts to regional flood frequency analysis that were based on fixed regions, later the Hosking and Wallis's (HW; 1997) theory was adopted and modified. Nevertheless, it turned out to be that delineating homogeneous regions using these approaches is not a straightforwar