4,583 research outputs found

    Effects of Proline and Glycine on the Cnidocyte Discharge of Hydra magnipapillata

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    The sense of taste enables animals to utilize environmental cues to detect favorable foods. Through specialized sensory receptors, Cnidarians employ stinging cells called cnidocytes to perform a variety of activities such as locomotion, capturing prey, inducing of feeding responses, and defense. Their discharge is highly regulated by mechanical and chemical signals that are mediated by a complex system including the opsin and taste pathways. Taste 1 Receptors (T1R) have previously been isolated in vertebrates but only until recently, have been noted in invertebrates. Receptors specific to L- amino acids corresponding to the taste sensation of umami, were studied to determine if the pathways of Hydra magnipapillata used for feeding were similar to the systems utilized in vertebrates. Amino acids, Proline and Glycine, were experimented using cnidocyte assays to induce feeding and capture cnidocytes. An optimal concentration of 10mM of Proline and Glycine was tested and found to be significant by eliciting greater cnidocyte discharge as compared to a Control of gelatin with P- Values of 0.003 and 0.0011 respectively. This indicates that amino acids, which have similar receptors in vertebrates, are capable of inducing feeding responses in invertebrates implying that T1Rs operate in similar mechanisms thus predating the current notion of the evolutions and diversification of such genes by around 400 million years

    A stochastic model of turbulent mixing with chemical reaction: Nitric oxide formulation in a plug-flow burner

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    A stochastic model of turbulent mixing was developed for a reactor in which mixing is represented by n-body fluid particle interactions. The model was used to justify the assumption (made in previous investigations of the role of turbulent mixing on burner generated thermal nitric oxide and carbon monoxide emissions) that for a simple plug flow reactor, composition nonuniformities can be described by a Gaussian distribution function in the local fuel:air equivalence ratio. Recent extensions of this stochastic model to include the combined effects of turbulent mixing and secondary air entrainment on thermal generation of nitric oxide in gas turbine combustors are discussed. Finally, rate limited upper and lower bounds of the nitric oxide produced by thermal fixation of molecular nitrogen and oxidation of organically bound fuel nitrogen are estimated on the basis of the stochastic model for a plug flow burner; these are compared with experimental measurements obtained using a laboratory burner operated over a wide range of test conditions; good agreement is obtained

    COLA. III. Radio Detection of Active Galactic Nucleus in Compact Moderate Luminosity Infrared Galaxies

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    We present results from 4.8 GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median L_(IR) = 10^(11.01) L_☉) COLA sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (~10^(21) W Hz^(–1)) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity

    Undiagnosed asthma in older people: an underestimated problem

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    The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included.WHAT WE NEED TO KNOW: Are older people with respiratory symptoms aware this could be asthma? Which explanations for undiagnosed asthma apply most commonly in older Australians with asthma? Can we improve awareness of asthma in older people with undiagnosed asthma? Is the possibility of asthma in older people firmly established on the general practitioners’ radar screen? What reasons most often determine whether GPs perform spirometry in their practice? WHAT WE NEED TO DO: Conduct a representative population study to assess whether older Australians recognise respiratory symptoms as being asthma and are reporting these symptoms. Conduct and evaluate a pilot asthma health promotion program for older people. Conduct a controlled therapeutic trial of people with undiagnosed asthma to assess treatment benefits and produce treatment recommendations. Identify whether the prominence of asthma in older people can be brought to the attention of GPs. Analyse more carefully the issues associated with innovation of office spirometry.David H Wilson, Sarah L Appleton, Robert J Adams and Richard E Ruffi

    Kinematic Masses of Super Star Clusters in M82 from High-Resolution Near-Infrared Spectroscopy

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    Using high-resolution (R~22,000) near-infrared (1.51 -- 1.75 microns) spectra from Keck Observatory, we measure the kinematic masses of two super star clusters in M82. Cross-correlation of the spectra with template spectra of cool evolved stars gives stellar velocity dispersions of sigma_r=15.9 +/- 0.8 km/s for MGG-9 and sigma_r=11.4 +/- 0.8 km/s for MGG-11. The cluster spectra are dominated by the light of red supergiants, and correlate most closely with template supergiants of spectral types M0 and M4.5. We fit King models to the observed profiles of the clusters in archival HST/NICMOS images to measure the half-light radii. Applying the virial theorem, we determine masses of 1.5 +/- 0.3 x 10^6 M_sun for MGG-9 and 3.5 +/- 0.7 x 10^5 M_sun for MGG-11. Population synthesis modelling suggests that MGG-9 is consistent with a standard initial mass function, whereas MGG-11 appears to be deficient in low-mass stars relative to a standard IMF. There is, however, evidence of mass segregation in the clusters, in which case the virial mass estimates would represent lower limits.Comment: 16 pages, 8 figures; ApJ, in pres

    An algorithmic approach to diagnosing asthma in older patients in general practice

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    The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included.WHAT WE NEED TO KNOW: How effective would an algorithm be in helping general practitioners diagnose asthma? What proportion of older people with undiagnosed asthma fail to recognise symptoms? What proportion of the population believe asthma does not occur in the older population? What systems or supports do GPs need to diagnose asthma more effectively? WHAT WE NEED TO DO: Work on developing a gold standard for asthma diagnosis. Develop prototype algorithms for general practice discussion. Conduct a general practice study to assess the effectiveness of an algorithm. In conjunction with GPs, develop a pilot program to increase awareness of the current asthma problem. Conduct focus-group research to identify why some people do not believe they can develop asthma for the first time in adult life. Conduct focus-group research to identify why some adults do not attribute asthma symptoms to asthma. Conduct focus groups with GPs to identify what support is needed to diagnose asthma more effectively. Consult with all stakeholders before an intervention is used. Evaluate any interventions used.Richard E Ruffin, David H Wilson, Sarah L Appleton and Robert J Adam

    Star Formation Across the Taffy Bridge: UGC 12914/15

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    We present BIMA two-field mosaic CO(1-0) images of the Taffy galaxies (UGC 12914/15), which show the distinct taffy-like radio continuum emission bridging the two spiral disks. Large amounts of molecular gas (1.4 x 10^{10} Msun, using the standard Galactic CO-to-H2_2 conversion applicable to Galactic disk giant molecular clouds [GMCs]) were clearly detected throughout the taffy bridge between the two galaxies, which, as in the more extreme case of HI, presumably results from a head-on collision between the two galaxies. The highest CO concentration between the two galaxies corresponds to the H_alpha source in the taffy bridge near the intruder galaxy UGC 12915. This HII region is also associated with the strongest source of radio continuum in the bridge, and shows both morphological and kinematic connections to UGC 12915. The overall CO distribution of the entire system agrees well with that of the radio continuum emission, particularly in the taffy bridge. This argues for the star formation origin of a significant portion of the radio continuum emission. Compared to the HI morphology and kinematics, which are strongly distorted owing to the high-speed collision, CO better defines the orbital geometry and impact parameter of the interaction, as well as the disk properties (e.g., rotation, orientation) of the progenitor galaxies. Based on the 20cm-to-CO ratio maps, we conclude that the starburst sites are primarily located in UGC 12915 and the H_alpha source in the bridge and show that the molecular gas in the taffy bridge is forming into stars with star formation efficiency comparable to that of the target galaxy UGC 12914 and similar to that in the Galactic disk.Comment: Minor typo/style corrections to match with the published version (AJ, Nov. issue). A single .ps.gz file of the entire paper can be downloaded from http://spider.ipac.caltech.edu/staff/gao/Taffy/all.ps.g

    Ventricular Tachycardia in the Absence of Structural Heart Disease

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    In up to 10% of patients who present with ventricular tachycardia (VT), obvious structural heart disease is not identified. In such patients, causes of ventricular arrhythmia include right ventricular outflow tract (RVOT) VT, extrasystoles, idiopathic left ventricular tachycardia (ILVT), idiopathic propranolol-sensitive VT (IPVT), catecholaminergic polymorphic VT (CPVT), Brugada syndrome, and long QT syndrome (LQTS). RVOT VT, ILVT, and IPVT are referred to as idiopathic VT and generally do not have a familial basis. RVOT VT and ILVT are monomorphic, whereas IPVT may be monomorphic or polymorphic. The idiopathic VTs are classified by the ventricle of origin, the response to pharmacologic agents, catecholamine dependence, and the specific morphologic features of the arrhythmia. CPVT, Brugada syndrome, and LQTS are inherited ion channelopathies. CPVT may present as bidirectional VT, polymorphic VT, or catecholaminergic ventricular fibrillation. Syncope and sudden death in Brugada syndrome are usually due to polymorphic VT. The characteristic arrhythmia of LQTS is torsades de pointes. Overall, patients with idiopathic VT have a better prognosis than do patients with ventricular arrhythmias and structural heart disease. Initial treatment approach is pharmacologic and radiofrequency ablation is curative in most patients. However, radiofrequency ablation is not useful in the management of inherited ion channelopathies. Prognosis for patients with VT secondary to ion channelopathies is variable. High-risk patients (recurrent syncope and sudden cardiac death survivors) with inherited ion channelopathies benefit from implantable cardioverter-defibrillator placement. This paper reviews the mechanism, clinical presentation, and management of VT in the absence of structural heart disease
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