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Search Results: 1 - 10 of 6555 matches for " Jeffrey Conn "
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A Hierarchical Modeling Framework for Multiple Observer Transect Surveys
Paul B. Conn, Jeffrey L. Laake, Devin S. Johnson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042294
Abstract: Ecologists often use multiple observer transect surveys to census animal populations. In addition to animal counts, these surveys produce sequences of detections and non-detections for each observer. When combined with additional data (i.e. covariates such as distance from the transect line), these sequences provide the additional information to estimate absolute abundance when detectability on the transect line is less than one. Although existing analysis approaches for such data have proven extremely useful, they have some limitations. For instance, it is difficult to extrapolate from observed areas to unobserved areas unless a rigorous sampling design is adhered to; it is also difficult to share information across spatial and temporal domains or to accommodate habitat-abundance relationships. In this paper, we introduce a hierarchical modeling framework for multiple observer line transects that removes these limitations. In particular, abundance intensities can be modeled as a function of habitat covariates, making it easier to extrapolate to unsampled areas. Our approach relies on a complete data representation of the state space, where unobserved animals and their covariates are modeled using a reversible jump Markov chain Monte Carlo algorithm. Observer detections are modeled via a bivariate normal distribution on the probit scale, with dependence induced by a distance-dependent correlation parameter. We illustrate performance of our approach with simulated data and on a known population of golf tees. In both cases, we show that our hierarchical modeling approach yields accurate inference about abundance and related parameters. In addition, we obtain accurate inference about population-level covariates (e.g. group size). We recommend that ecologists consider using hierarchical models when analyzing multiple-observer transect data, especially when it is difficult to rigorously follow pre-specified sampling designs. We provide a new R package, hierarchicalDS, to facilitate the building and fitting of these models.
Prednisone on the threshold of rational use in the treatment of rheumatoid arthritis  [PDF]
Doyt L. Conn
Health (Health) , 2013, DOI: 10.4236/health.2013.58A1001
Abstract:

This is a review of the evolution of the use prednisone in the treatment of rheumatoid arthritis (RA). Cortisone was introduced in 1949 and shortly thereafter, the Mayo investigators found that low divided doses with slow tapering were effective and caused fewer side effects. In 1959, a British double blind 2 year study of prednisolone treatment in early RA demonstrated effectiveness and reduced bony erosions. This experience was lost over time and empiricism and efforts to reduce side effects dominated practice for the next 35 years. Since 1995, a number of controlled studies of low single daily doses of prednisone in early RA have been reported by European investigators. They have shown clinical improvement, reduced bony erosions, augmentation of the effect of dmards and few side effects. During the last 25 years, the molecular actions of glucocorticoids have been elucidated. The time relationship of the dose to the biologic and clinical effects has been established. As a result of the information on the diurnal effect of glucocorticoids and the documentation of the effect occurring 5-6 hours after the dose and dissipating by 24 hours, a delayed release preparation of prednisone has been developed. With the rediscovery of the effectiveness of low single daily morning dose of prednisone in early RA by controlled studies and the demonstration of the onset and duration of the clinical effect of low dose of prednisone, it is now possible to use low doses of prednisone rationally and effectively in the treatment of RA. It remains to be determined whether a single morning, single evening or a twice a day low dose is the most effective and safe. It is doubtful if the new delayed release prednisone is any more effective than the usual immediate release prednisone if given at the same time.

MGluR5 Mediates the Interaction between Late-LTP, Network Activity, and Learning
Arthur Bikbaev, Sergey Neyman, Richard Teke Ngomba, Jeffrey Conn, Ferdinando Nicoletti, Denise Manahan-Vaughan
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002155
Abstract: Hippocampal synaptic plasticity and learning are strongly regulated by metabotropic glutamate receptors (mGluRs) and particularly by mGluR5. Here, we investigated the mechanisms underlying mGluR5-modulation of these phenomena. Prolonged pharmacological blockade of mGluR5 with MPEP produced a profound impairment of spatial memory. Effects were associated with 1) a reduction of mGluR1a-expression in the dentate gyrus; 2) impaired dentate gyrus LTP; 3) enhanced CA1-LTP and 4) suppressed theta (5–10 Hz) and gamma (30–100 Hz) oscillations in the dentate gyrus. Allosteric potentiation of mGluR1 after mGluR5 blockade significantly ameliorated dentate gyrus LTP, as well as suppression of gamma oscillatory activity. CA3-lesioning prevented MPEP effects on CA1-LTP, suggesting that plasticity levels in CA1 are driven by mGluR5-dependent synaptic and network activity in the dentate gyrus. These data support the hypothesis that prolonged mGluR5-inactivation causes altered hippocampal LTP levels and network activity, which is mediated in part by impaired mGluR1-expression in the dentate gyrus. The consequence is impairment of long-term learning.
Systematics and Population Level Analysis of Anopheles darlingi
Conn JE
Memórias do Instituto Oswaldo Cruz , 1998,
Abstract: A new phylogenetic analysis of the Nyssorhynchus subgenus (Danoff-Burg and Conn, unpub. data) using six data sets {morphological (all life stages); scanning electron micrographs of eggs; nuclear ITS2 sequences; mitochondrial COII, ND2 and ND6 sequences} revealed different topologies when each data set was analyzed separately but no heterogeneity between the data sets using the arn test. Consequently, the most accurate estimate of the phylogeny was obtained when all the data were combined. This new phylogeny supports a monophyletic Nyssorhynchus subgenus but both previously recognized sections in the subgenus (Albimanus and Argyritarsis) were demonstrated to be paraphyletic relative to each other and four of the seven clades included species previously placed in both sections. One of these clades includes both Anopheles darlingi and An. albimanus, suggesting that the ability to vector malaria effectively may have originated once in this subgenus. Both a conserved (315 bp) and a variable (425 bp) region of the mitochondrial COI gene from 15 populations of An. darlingi from Belize, Bolivia, Brazil, French Guiana, Peru and Venezuela were used to examine the evolutionary history of this species and to test several analytical assumptions. Results demonstrated (1) parsimony analysis is equally informative compared to distance analysis using NJ; (2) clades or clusters are more strongly supported when these two regions are combined compared to either region separately; (3) evidence (in the form of remnants of older haplotype lineages) for two colonization events; and (4) significant genetic divergence within the population from Peixoto de Azevedo (State of Mato Grosso, Brazil). The oldest lineage includes populations from Peixoto, Boa Vista (State of Roraima) and Dourado (State of S o Paulo).
Pharmacoperone Identification for Therapeutic Rescue of Misfolded Mutant Proteins
P. Michael Conn
Frontiers in Endocrinology , 2011, DOI: 10.3389/fendo.2011.00006
Abstract: G protein-coupled receptors (GPCRs), which includes the gonadotropin-releasing hormone (GnRH) receptor (GnRHR), comprises the largest family of validated drug targets – more than half of all approved drugs derive their benefits by selective targeting of GPCRs. Most drugs in this class are either agonists or antagonists of GPCRs and high throughput screens have typically been designed and performed with a view toward identification of such compounds as lead drug candidates. This manuscript presents the case that valuable drugs which effect the trafficking of GPCRs may have been overlooked because pharmacoperones have been selected from existing screens that identify agonists and antagonists. A “gain of activity assay” is proposed; this assay relies on the expression of a mutant of the GnRHR that is known to be rescuable by pharmacoperone drugs, and which is restored to activity in their presence. Accordingly, “hits” are identified by the appearance of activity. The gene for the mutant is under control of tetracycline and may be prevented from being expressed. This is a valuable feature since it allows false positives to be identified. Such drugs will show apparent activity whether or not the mutant is expressed. This assay will enable identification of these drugs from chemical libraries and does not rely on their activity as agonists or antagonists.
Diffuse UV Background: GALEX Results
Richard Conn Henry
Physics , 2009,
Abstract: A bright UV GALEX image in the direction of a dense high galactic latitude interstellar dust cloud is examined to test (and to reject) the idea that a bright extragalactic UV background radiation field exists. A GALEX "Deep Imaging Survey" image of a second high latitude region (a region almost totally free of dust) shows a similar bright background, which, clearly, cannot be due to starlight scattered from interstellar dust. I speculate that the background is due to dark matter particles interacting with interstellar gas/dust nucleons.
Progress in Understanding the Diffuse UV Cosmic Background
Richard Conn Henry
Physics , 2012,
Abstract: I report on progress in my ongoing work with Professor Jayant Murthy concerning the origin and nature of the diffuse ultraviolet background radiation over the sky. We have obtained and are reducing a vast trove of Voyager ultraviolet spectrometer observations of the diffuse background shortward of Lyman alpha, including for the first time measurements made from the outermost regions of the solar system, where noise from solar-system scattered (and then grating-scattered) solar Lyman alpha is lowest. Also, we have obtained and are investigating the complete set of GALEX observations of the diffuse ultraviolet background longward of Lyman alpha. Preliminary investigation appears to confirm that longward of Lyman alpha there exists a component of the diffuse ultraviolet background that is not dust-scattered starlight.
The Local Interstellar Ultraviolet Radiation Field
Richard Conn Henry
Physics , 2002,
Abstract: I have used the Hipparcos Input Catalog, together with Kurucz model stellar atmospheres, and information on the strength of the interstellar extinction, to create a model of the expected intensity and spectral distribution of the local interstellar ultraviolet radiation field, under various assumptions concerning the albedo a of the interstellar grains. (This ultraviolet radiation field is of particular interest because of the fact that ultraviolet radiation is capable of profoundly affecting the chemistry of the interstellar medium.) By comparing my models with the observations, I am able to conclude that the albedo a of the interstellar grains in the far ultraviolet is very low, perhaps a = 0.1. I also advance arguments that my present determination of this albedo is much more reliable than any of the many previous (and conflicting) ultraviolet interstellar grain albedo determinations. Beyond this, I show that the ultraviolet background radiation that is observed at high galactic latitudes must be extragalactic in origin, as it cannot be backscatter of the interstellar radiation field.
Fecundity, parity, and adult feeding relationships among Nyssorhynchus malaria vectors from Venezuela
Lounibos, L. P.;Conn, Jan;
Memórias do Instituto Oswaldo Cruz , 1991, DOI: 10.1590/S0074-02761991000100010
Abstract: relative to their pre-engorgement weights, nulliparous anopheles nuneztovari consumed significantly smaller blood meals than a. marajoara, a. triannulatus or a. aquasalis. when females were deprived of sugar before blood feeding, only one-quarter of a. nuneztovari, but more than two-thirds of a. marajoara, a. triannulatus and a. aquasalis matured eggs. sugar feeding before blood, or two sucessive blood meals by sugar-deprived females, increased the proportion of nulliparous a. nuneztovari which developed eggs, but not significantly so. nearly all individuals of nulliparous, sugar-fed a. marajoara, a. triannulatus and a. aquasalis matured eggs after one blood feeding. among a. nuneztovari, a. marajoara and a. aquasalis that matured some eggs in the laboratory, there were no positive correlations between the number of eggs developed and relative vlood mealsize. however, blood meals larger than the mean size significantly increased the chance that a. nuneztovari would develop some eggs. mean fecundities of gravid a. nuneztovari and a. marajoara reared in the laboratory were significantly lower than those of the same species captured at human bait in nature. post-engorgement access to sugar by a. nuneztovari (captured at human bait) did not influence fecundity, but significantly enhanced survivorship and the proporticon of individuals which retained eggs. release-recapture experiments revealed that relatively small blood meals are typical of a. nuneztovari only during the first gonotrophic cycle. we suggest that multiple blood feeding, seemingly necessary for most a. nuneztovari to develop a first clutch of eggs, may increase the probability of infection with plasmodium vivax where this mosquito species is a primary vector.
Dust-Scattered Ultraviolet Halos around Bright Stars
Jayant Murthy,Richard Conn Henry
Physics , 2010, DOI: 10.1088/0004-637X/734/1/13
Abstract: We have discovered ultraviolet halos extending as far as 5{\deg} around four (of six) bright UV stars using data from the GALEX satellite. These halos are due to the scattering of the starlight from nearby thin, foreground dust clouds. We have placed limits of 0.58 $\pm$ 0.12 and 0.72 $\pm$ 0.06 on the phase function asymmetry factor (g) and limits on the albedo of 0.10 $\pm$ 0.05 and 0.26 $\pm$ 0.10 in the FUV (1521 {\AA}) and NUV (2320 {\AA}) bands, respectively. We suggest that these halos are a common feature around bright stars and may be used to explore the scattering function of interstellar grains at small angles.
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