174 research outputs found
Ichthyoplankton Adjacent to Live-Bottom Habitats in Onslow Bay, North Carolina
The abundance and distribution of ichthyoplankton adjacent to live-bottom habitats (rock outcroppings containing rich, sessile invertebrate communities and many species of
tropical and subtropical fishes) in open-shelf waters « 55-m isobath) in Onslow Bay, North Carolina, were investigated. Larvae of reef-associated genera, especially the economically important subtropical and tropical members of the families Haemulidae (Haemulon), Lutjanidae (Lutjanus and Rltomboplites), Serranidae (Mycteroperca and Epinephelus), and Sparidae (Calamus and Pagrus) were targeted. Larvae representing 40 families were collected in neuston tows. Commonly collected reef-associated families were Balistidae, Blenniidae (dominated by the reef-associated Parablennius marmoreus) , Mullidae, and Gobiidae. Larvae representing 70 families were
collected in subsurface tows. Reef-associated families commonly collected included Apogonidae, Balistidae, Gobiidae, Haemulidae, LutJanidae, Scaridae, and Serranidae. Larval Haemulon sp (p)., Lutjanus sp(p)., and Rltomboplites aurorubens were commonly collected and thus it is likely that these taxa spawn in Onslow Bay and recruit to live-bottom sites within the area. Other families of fishes commonly collected but generally not considered reef-associated included Bothidae, Callionymidae, Carangidae, Clupeidae, Engraulidae, and Ophidiidae. Estuarine-dependent species (e.g. the clupeid Brevoortia tyrannus and the sciaenids Leiostomus xanthurus and Micropogonias undulatus) were an important component of the ichthyoplankton during late fall and winter. The frequent occurrence of larvae from
oceanic species (e.g. gonostomatids and myctophids) indicated that Gulf Stream waters had intruded onto the shelf, transporting these larvae to open-shelf waters off North Carolina.(PDF file containes 36 pages.
Association between MAPT haplotype and memory function in patients with Parkinson's disease and healthy aging individuals.
Genetic variation is associated with differences in the function of the brain as well as its susceptibility to disease. The common H1 haplotypic variant of the microtubule-associated protein tau gene (MAPT) has been related to an increased risk for Parkinson's disease (PD). Furthermore, among PD patients, H1 homozygotes have an accelerated progression to dementia. We investigated the neurocognitive correlates of MAPT haplotypes using functional magnetic resonance imaging. Thirty-seven nondemented patients with PD (19 H1/H1, 18 H2 carriers) and 40 age-matched controls (21 H1/H1, 19 H2 carriers) were scanned during performance of a picture memory encoding task. Behaviorally, H1 homozygosity was associated with impaired picture recognition memory in PD patients and control subjects. These impairments in the H1 homozygotes were accompanied by an altered blood-oxygen level-dependent response in the medial temporal lobe during successful memory encoding. Additional age-related differences in blood-oxygen level-dependent response were observed in the medial temporal lobes of H1 homozygotes with PD. These results suggest that common variation in MAPT is not only associated with the dementia of PD but also differences in the neural circuitry underlying aspects of cognition in normal aging.This work was funded by Parkinson's UK, the Medical Research Council, the Wellcome Trust (088324), and the NIHR Comprehensive Biomedical Research Centre (RG64473). The BCNI is co-funded by the MRC and Wellcome Trust. Sophie E. Winder-Rhodes received PhD funding from a Merck Sharp and Dohme studentship.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.neurobiolaging.2014.12.006
Vitamin D with Calcium reduces mortality: patient level pooled analysis of 70,528 patients from eight major vitamin D trials
Introduction: Vitamin D may affect multiple health outcomes. If so, an effect on mortality is to be expected. Using pooled data from randomized controlled trials, we performed individual patient data (IPD) and trial level meta-analyses to assess mortality among participants randomized to either vitamin D alone or vitamin D with calcium.
Subjects and Methods: Through a systematic literature search, we identified 24 randomized controlled trials reporting data on mortality in which vitamin D was given either alone or with calcium. From a total of 13 trials with more than 1000 participants each, eight trials were included in our IPD analysis. Using a stratified Cox regression model, we calculated risk of death during 3 yr of treatment in an intention-to-treat analysis. Also, we performed a trial level meta-analysis including data from all studies.
Results: The IPD analysis yielded data on 70,528 randomized participants (86.8% females) with a median age of 70 (interquartile range, 62–77) yr. Vitamin D with or without calcium reduced mortality by 7% [hazard ratio, 0.93; 95% confidence interval (CI), 0.88–0.99]. However, vitamin D alone did not affect mortality, but risk of death was reduced if vitamin D was given with calcium (hazard ratio, 0.91; 95% CI, 0.84–0.98). The number needed to treat with vitamin D plus calcium for 3 yr to prevent one death was 151. Trial level meta-analysis (24 trials with 88,097 participants) showed similar results, i.e. mortality was reduced with vitamin D plus calcium (odds ratio, 0.94; 95% CI, 0.88–0.99), but not with vitamin D alone (odds ratio, 0.98; 95% CI, 0.91–1.06).
Conclusion: Vitamin D with calcium reduces mortality in the elderly, whereas available data do not support an effect of vitamin D alone
A doubly-refined enumeration of alternating sign matrices and descending plane partitions
It was shown recently by the authors that, for any n, there is equality
between the distributions of certain triplets of statistics on nxn alternating
sign matrices (ASMs) and descending plane partitions (DPPs) with each part at
most n. The statistics for an ASM A are the number of generalized inversions in
A, the number of -1's in A and the number of 0's to the left of the 1 in the
first row of A, and the respective statistics for a DPP D are the number of
nonspecial parts in D, the number of special parts in D and the number of n's
in D. Here, the result is generalized to include a fourth statistic for each
type of object, where this is the number of 0's to the right of the 1 in the
last row of an ASM, and the number of (n-1)'s plus the number of rows of length
n-1 in a DPP. This generalization is proved using the known equality of the
three-statistic generating functions, together with relations which express
each four-statistic generating function in terms of its three-statistic
counterpart. These relations are obtained by applying the Desnanot-Jacobi
identity to determinantal expressions for the generating functions, where the
determinants arise from standard methods involving the six-vertex model with
domain-wall boundary conditions for ASMs, and nonintersecting lattice paths for
DPPs.Comment: 28 pages; v2: published versio
Science and Ideology in Economic, Political, and Social Thought
This paper has two sources: One is my own research in three broad areas: business cycles, economic measurement and social choice. In all of these fields I attempted to apply the basic precepts of the scientific method as it is understood in the natural sciences. I found that my effort at using natural science methods in economics was met with little understanding and often considerable hostility. I found economics to be driven less by common sense and empirical evidence, then by various ideologies that exhibited either a political or a methodological bias, or both. This brings me to the second source: Several books have appeared recently that describe in historical terms the ideological forces that have shaped either the direct areas in which I worked, or a broader background. These books taught me that the ideological forces in the social sciences are even stronger than I imagined on the basis of my own experiences.
The scientific method is the antipode to ideology. I feel that the scientific work that I have done on specific, long standing and fundamental problems in economics and political science have given me additional insights into the destructive role of ideology beyond the history of thought orientation of the works I will be discussing
Multiply-refined enumeration of alternating sign matrices
Four natural boundary statistics and two natural bulk statistics are
considered for alternating sign matrices (ASMs). Specifically, these statistics
are the positions of the 1's in the first and last rows and columns of an ASM,
and the numbers of generalized inversions and -1's in an ASM. Previously-known
and related results for the exact enumeration of ASMs with prescribed values of
some of these statistics are discussed in detail. A quadratic relation which
recursively determines the generating function associated with all six
statistics is then obtained. This relation also leads to various new identities
satisfied by generating functions associated with fewer than six of the
statistics. The derivation of the relation involves combining the
Desnanot-Jacobi determinant identity with the Izergin-Korepin formula for the
partition function of the six-vertex model with domain-wall boundary
conditions.Comment: 62 pages; v3 slightly updated relative to published versio
Altered subcortical emotional salience processing differentiates Parkinson’s patients with and without psychotic symptoms
Objective
Current research does not provide a clear explanation for why some patients with Parkinson’s Disease (PD) develop psychotic symptoms. The ‘aberrant salience hypothesis’ of psychosis has been influential and proposes that dopaminergic dysregulation leads to inappropriate attribution of salience to irrelevant/non-informative stimuli, facilitating the formation of hallucinations and delusions. The aim of this study is to investigate whether non-motivational salience is altered in PD patients and possibly linked to the development of psychotic symptoms.
Methods
We investigated salience processing in 14 PD patients with psychotic symptoms, 23 PD patients without psychotic symptoms and 19 healthy controls. All patients were on dopaminergic medication for their PD. We examined emotional salience using a visual oddball fMRI paradigm that has been used to investigate early stages of schizophrenia spectrum psychosis, controlling for resting cerebral blood flow as assessed with arterial spin labelling fMRI.
Results
We found significant differences between patient groups in brain responses to emotional salience. PD patients with psychotic symptoms had enhanced brain responses in the striatum, dopaminergic midbrain, hippocampus and amygdala compared to patients without psychotic symptoms. PD patients with psychotic symptoms showed significant correlations between the levels of dopaminergic drugs they were taking and BOLD signalling, as well as psychotic symptom scores.
Conclusion
Our study suggests that enhanced signalling in the striatum, dopaminergic midbrain, the hippocampus and amygdala is associated with the development of psychotic symptoms in PD, in line with that proposed in the ‘aberrant salience hypothesis’ of psychosis in schizophrenia
Atomoxetine restores the response inhibition network in Parkinson's disease
Parkinson's disease impairs the inhibition of responses, and whilst impulsivity is mild for some patients, severe impulse control disorders affect ∼10% of cases. Based on preclinical models we proposed that noradrenergic denervation contributes to the impairment of response inhibition, via changes in the prefrontal cortex and its subcortical connections. Previous work in Parkinson's disease found that the selective noradrenaline reuptake inhibitor atomoxetine could improve response inhibition, gambling decisions and reflection impulsivity. Here we tested the hypotheses that atomoxetine can restore functional brain networks for response inhibition in Parkinson's disease, and that both structural and functional connectivity determine the behavioural effect. In a randomized, double-blind placebo-controlled crossover study, 19 patients with mild-to-moderate idiopathic Parkinson's disease underwent functional magnetic resonance imaging during a stop-signal task, while on their usual dopaminergic therapy. Patients received 40 mg atomoxetine or placebo, orally. This regimen anticipates that noradrenergic therapies for behavioural symptoms would be adjunctive to, not a replacement for, dopaminergic therapy. Twenty matched control participants provided normative data. Arterial spin labelling identified no significant changes in regional perfusion. We assessed functional interactions between key frontal and subcortical brain areas for response inhibition, by comparing 20 dynamic causal models of the response inhibition network, inverted to the functional magnetic resonance imaging data and compared using random effects model selection. We found that the normal interaction between pre-supplementary motor cortex and the inferior frontal gyrus was absent in Parkinson's disease patients on placebo (despite dopaminergic therapy), but this connection was restored by atomoxetine. The behavioural change in response inhibition (improvement indicated by reduced stop-signal reaction time) following atomoxetine correlated with structural connectivity as measured by the fractional anisotropy in the white matter underlying the inferior frontal gyrus. Using multiple regression models, we examined the factors that influenced the individual differences in the response to atomoxetine: the reduction in stop-signal reaction time correlated with structural connectivity and baseline performance, while disease severity and drug plasma level predicted the change in fronto-striatal effective connectivity following atomoxetine. These results suggest that (i) atomoxetine increases sensitivity of the inferior frontal gyrus to afferent inputs from the pre-supplementary motor cortex; (ii) atomoxetine can enhance downstream modulation of frontal-subcortical connections for response inhibition; and (iii) the behavioural consequences of treatment are dependent on fronto-striatal structural connections. The individual differences in behavioural responses to atomoxetine highlight the need for patient stratification in future clinical trials of noradrenergic therapies for Parkinson's disease.This work was primarily funded by the Wellcome Trust (103838) with additional support from the Medical Research Council (MC-A060-5PQ30, and RG62761), the NIHR Cambridge Biomedical Research Centre, Parkinson's UK and the James F McDonnell Foundation. The BCNI is supported by the Wellcome Trust and Medical Research Council
The A's, G's, C's, and T's of health disparities
In order to eliminate health disparities in the United States, more efforts are needed to address the breadth of social issues directly contributing to the healthy divide observed across racial and ethnic groups. Socioeconomic status, education, and the environment are intimately linked to health outcomes. However, with the tremendous advances in technology and increased investigation into human genetic variation, genomics is poised to play a valuable role in bolstering efforts to find new treatments and preventions for chronic conditions and diseases that disparately affect certain ethnic groups. Promising studies focused on understanding the genetic underpinnings of diseases such as prostate cancer or beta-blocker treatments for heart failure are illustrative of the positive contribution that genomics can have on improving minority health
Verbal fluency in Huntington’s disease: a longitudinal analysis of phonemic and semantic clustering and switching
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