721 research outputs found

    The Allometry of the Palate of Archaic \u3cem\u3eHomo sapiens\u3c/em\u3e and Modern \u3cem\u3eHomo sapiens\u3c/em\u3e

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    This research examines several aspects of allometry in the palate of archaic Homo sapiens and modern Homo sapiens. The allometry of the modern human palate is described. Comparisons between quantitative methods and comparisons between different types of samples are undertaken. Additionally, the allometry of the archaic Homo sapiens palate is described and analyzed. Finally, allometric comparisons between these groups are made. The samples employed in this study consist of 132 Amerindian (Arikara) crania and 21 archaic Homo sapiens (primarily Neandertal) crania. Quantitative methods used for analyzing these groups include least-squares regression, reduced major axis regression, and principal components analysis. Analysis of covariance and principal components analysis are used to compare allometric relationships between the groups. The results of this research indicate that least-squares regression techniques supply information which is generally substantiated by principal components analysis. Comparisons between samples indicate that static samples (samples derived from a single age group) do not provide the same information as ontogenetic samples (derived from several different age classes. These results are similar in both groups. The most important aspect of this study concerns the allometric relationships between modern and archaic Homo sapiens. Comparisons suggest that archaic Homo sapiens begin growth at larger sizes than modern Homo sapiens, and that this difference holds throughout the growth period. Complementary multivariate analyses indicate that the pattern or general size increase between these two groups is very similar

    Automated, high accuracy classification of Parkinsonian disorders: a pattern recognition approach

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    Progressive supranuclear palsy (PSP), multiple system atrophy (MSA) and idiopathic Parkinson’s disease (IPD) can be clinically indistinguishable, especially in the early stages, despite distinct patterns of molecular pathology. Structural neuroimaging holds promise for providing objective biomarkers for discriminating these diseases at the single subject level but all studies to date have reported incomplete separation of disease groups. In this study, we employed multi-class pattern recognition to assess the value of anatomical patterns derived from a widely available structural neuroimaging sequence for automated classification of these disorders. To achieve this, 17 patients with PSP, 14 with IPD and 19 with MSA were scanned using structural MRI along with 19 healthy controls (HCs). An advanced probabilistic pattern recognition approach was employed to evaluate the diagnostic value of several pre-defined anatomical patterns for discriminating the disorders, including: (i) a subcortical motor network; (ii) each of its component regions and (iii) the whole brain. All disease groups could be discriminated simultaneously with high accuracy using the subcortical motor network. The region providing the most accurate predictions overall was the midbrain/brainstem, which discriminated all disease groups from one another and from HCs. The subcortical network also produced more accurate predictions than the whole brain and all of its constituent regions. PSP was accurately predicted from the midbrain/brainstem, cerebellum and all basal ganglia compartments; MSA from the midbrain/brainstem and cerebellum and IPD from the midbrain/brainstem only. This study demonstrates that automated analysis of structural MRI can accurately predict diagnosis in individual patients with Parkinsonian disorders, and identifies distinct patterns of regional atrophy particularly useful for this process

    Effects of Endocannabinoid System Modulation on Cognitive and Emotional Behavior

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    Cannabis has long been known to produce cognitive and emotional effects. Research has shown that cannabinoid drugs produce these effects by driving the brain’s endogenous cannabinoid system and that this system plays a modulatory role in many cognitive and emotional processes. This review focuses on the effects of endocannabinoid system modulation in animal models of cognition (learning and memory) and emotion (anxiety and depression). We review studies in which natural or synthetic cannabinoid agonists were administered to directly stimulate cannabinoid receptors or, conversely, where cannabinoid antagonists were administered to inhibit the activity of cannabinoid receptors. In addition, studies are reviewed that involved genetic disruption of cannabinoid receptors or genetic or pharmacological manipulation of the endocannabinoid-degrading enzyme, fatty acid amide hydrolase (FAAH). Endocannabinoids affect the function of many neurotransmitter systems, some of which play opposing roles. The diversity of cannabinoid roles and the complexity of task-dependent activation of neuronal circuits may lead to the effects of endocannabinoid system modulation being strongly dependent on environmental conditions. Recent findings are reviewed that raise the possibility that endocannabinoid signaling may change the impact of environmental influences on emotional and cognitive behavior rather than selectively affecting any specific behavior

    Elemental abundances in M31: Individual and Coadded Spectroscopic [Fe/H] and [{\alpha}/Fe] throughout the M31 Halo with SPLASH

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    We present spectroscopic chemical abundances of red giant branch (RGB) stars in Andromeda (M31), using medium resolution (R6000R\sim6000) spectra obtained via the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) survey. In addition to individual chemical abundances, we coadd low signal-to-noise ratio (S/N) spectra of stars to obtain a high enough to measure average [Fe/H] and [α\alpha/Fe] abundances. We obtain individual and coadded measurements for [Fe/H] and [α\alpha/Fe] for M31 halo stars, covering a range of 9--180 kpc in projected radius from the center of M31. With these measurements, we greatly increase the number of outer halo (Rproj>50R_{\mathrm{proj}} > 50 kpc) M31 stars with spectroscopic [Fe/H] and [α\alpha/Fe], adding abundance measurements for 45 individual stars and 33 coadds from a pool of an additional 174 stars. We measure the spectroscopic metallicity ([Fe/H]) gradient, finding a negative radial gradient of 0.0050±0.0003-0.0050\pm0.0003 for all stars in the halo, consistent with gradient measurements obtained using photometric metallicities. Using the first measurements of [α\alpha/Fe] for M31 halo stars covering a large range of projected radii, we find a positive gradient (+0.0026±0.0004+0.0026\pm0.0004) in [α\alpha/Fe] as a function of projected radius. We also explore the distribution in [Fe/H]--[α\alpha/Fe] space as a function of projected radius for both individual and coadded measurements in the smooth halo, and compare these measurements to those stars potentially associated with substructure. These spectroscopic abundance distributions highlight the substantial evidence that M31 has had an appreciably different formation and merger history compared to our own Galaxy.Comment: Submitted to Ap

    Quantification of Proteins Using Peptide Immunoaffinity Enrichment Coupled with Mass Spectrometry

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    There is a great need for quantitative assays in measuring proteins. Traditional sandwich immunoassays, largely considered the gold standard in quantitation, are associated with a high cost, long lead time, and are fraught with drawbacks (e.g. heterophilic antibodies, autoantibody interference, 'hook-effect').1 An alternative technique is affinity enrichment of peptides coupled with quantitative mass spectrometry, commonly referred to as SISCAPA (Stable Isotope Standards and Capture by Anti-Peptide Antibodies).2 In this technique, affinity enrichment of peptides with stable isotope dilution and detection by selected/multiple reaction monitoring mass spectrometry (SRM/MRM-MS) provides quantitative measurement of peptides as surrogates for their respective proteins. SRM/MRM-MS is well established for accurate quantitation of small molecules 3, 4 and more recently has been adapted to measure the concentrations of proteins in plasma and cell lysates.5-7 To achieve quantitation of proteins, these larger molecules are digested to component peptides using an enzyme such as trypsin. One or more selected peptides whose sequence is unique to the target protein in that species (i.e. "proteotypic" peptides) are then enriched from the sample using anti-peptide antibodies and measured as quantitative stoichiometric surrogates for protein concentration in the sample. Hence, coupled to stable isotope dilution (SID) methods (i.e. a spiked-in stable isotope labeled peptide standard), SRM/MRM can be used to measure concentrations of proteotypic peptides as surrogates for quantification of proteins in complex biological matrices. The assays have several advantages compared to traditional immunoassays. The reagents are relatively less expensive to generate, the specificity for the analyte is excellent, the assays can be highly multiplexed, enrichment can be performed from neat plasma (no depletion required), and the technique is amenable to a wide array of proteins or modifications of interest.8-13 In this video we demonstrate the basic protocol as adapted to a magnetic bead platform

    Case Study of Ecstatic Meditation: fMRI and EEG Evidence of Self-Stimulating a Reward System

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    We report the first neural recording during ecstatic meditations called jhanas and test whether a brain reward system plays a role in the joy reported. Jhanas are Altered States of Consciousness (ASC) that imply major brain changes based on subjective reports: (1) external awareness dims, (2) internal verbalizations fade, (3) the sense of personal boundaries is altered, (4) attention is highly focused on the object of meditation, and (5) joy increases to high levels. The fMRI and EEG results from an experienced meditator show changes in brain activity in 11 regions shown to be associated with the subjective reports, and these changes occur promptly after jhana is entered. In particular, the extreme joy is associated not only with activation of cortical processes but also with activation of the nucleus accumbens (NAc) in the dopamine/opioid reward system. We test three mechanisms by which the subject might stimulate his own reward system by external means and reject all three. Taken together, these results demonstrate an apparently novel method of self-stimulating a brain reward system using only internal mental processes in a highly trained subject

    Non-conformal examples of AdS/CFT

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    Asymptotically anti-de Sitter spacetimes with Poincare invariance along the boundary can describe, via the AdS/CFT correspondence, either relevant deformations of a conformal field theory or non-conformal vacuum states. I consider examples of both types constructed in the framework of five-dimensional gauged supergravity. I explain the proof and motivation of a gravitational ``c-theorem'' which is independent of dimension. I show how one class of examples can be elevated to ten-dimensional geometries involving distributions of parallel D3-branes. For these cases some peculiar properties of two-point functions emerge, and I close with speculations on their physical origin.Comment: 16 pages, two figures, latex. Strings '99 tal
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