The mysterious case of the C. elegans gut granule: death fluorescence, anthranilic acid and the kynurenine pathway

Gut granules are lysosome-like organelles with acidic interiors that are found in large numbers within the intestine of the nematode Caenorhabditis elegans. They are particularly prominent when viewed under ultraviolet light, which causes them to emit intense blue fluorescence. Yet the function of these large and abundant organelles in this heavily-studied model organism remains unclear. One possibility is that they serve as storage organelles, for example of zinc. A new clue to gut granule function is the identification of the blue fluorescent material that they contain as a glycosylated form of anthranilic acid, which is derived from tryptophan by action of the kynurenine pathway. This compound can also serve a surprising role as a natural, endogenous marker of organismal death

Interlimb Comparison of Electromyographic and Mechanomyographic Amplitude Responses of the Vastus Medialis to Submaximal and Maximal Isometric Contractions

Research on interlimb differences in neuromuscular recruitment patterns is limited. If interlimb differences exist, future exercise studies may have to reason for which limb (dominant vs. nondominant) to choose when examining muscle activation and contraction characteristics. PURPOSE: To investigate interlimb differences in normalized electromyographic (EMG) and mechanomyographic (MMG) amplitude responses of the vastus medialis muscle during submaximal and maximal isometric leg extension muscle actions. METHODS: Fourteen recreationally trained females (mean age ± SD = 22.3 ± 2.0 y) performed isometric leg extension muscle actions at 10-100% (10% increments) of maximal voluntary isometric contraction (MVIC) for their dominant (determined by kicking preference) and nondominant limbs. The muscle actions were performed unilaterally in the seated position of an isokinetic dynamometer. Subjects performed maximal isometric leg extension muscle actions for both limbs to determine each limb\u27s MVIC; then, they performed the submaximal isometric leg extension muscle actions in a random order of intensity. A bipolar surface EMG electrode arrangement and an accelerometer were placed over the vastus medialis muscle to detect EMG and MMG signals, respectively. The amplitudes of the EMG and MMG signals were expressed as root mean square (RMS) and normalized to their highest recorded value (% max). Two separate 2 (limb) × 10 (intensity) repeated measures ANOVAs were conducted to determine interlimb differences in normalized EMG and MMG RMS. RESULTS: There were no significant interactions for normalized EMG (p = 0.550) or MMG (p = 0.513) RMS. A main effect for limb was also not significant for normalized EMG (p = 0.653) or MMG (p = 0.490) RMS; however, a significant main effect for intensity was present for normalized EMG (10-90 \u3c 100, 10-80 \u3c 90, 10-60 \u3c 80, 10-50 \u3c 60 & 70, 20-30 \u3c 50, 20 \u3c 30 & 40% MVIC; p \u3c 0.001) and MMG (10-90 \u3c 100, 10-60 \u3c 90, 10-40 \u3c 70 & 80, 20 \u3c 60% MVIC; p \u3c 0.001) RMS. CONCLUSION: There were no interlimb differences in EMG or MMG RMS at submaximal and maximal isometric leg extension muscle actions. As they provided comparable information, either limb may be used for examining muscle activation and contraction characteristics in exercise studies using healthy, recreationally trained participants

Discovery of a flux-related change of the cyclotron line energy in Her X-1

We present the results of ten years of repeated measurements of the Cyclotron Resonance Scattering Feature (CRSF) in the spectrum of the binary X-ray pulsar Her X-1 and report the discovery of a positive correlation of the centroid energy of this absorption feature in pulse phase averaged spectra with source luminosity.Our results are based on a uniform analysis of observations bythe RXTE satellite from 1996 to 2005, using sufficiently long observations of 12 individual 35-day Main-On states of the source. The mean centroid energy E_c of the CRSF in pulse phase averaged spectra of Her X-1 during this time is around 40 keV, with significant variations from one Main-On state to the next. We find that the centroid energy of the CRSF in Her X-1 changes by ~5% in energy for a factor of 2 in luminosity. The correlation is positive, contrary to what is observed in some high luminosity transient pulsars. Our finding is the first significant measurement of a positive correlation between E_c and luminosity in any X-ray pulsar. We suggest that this behaviour is expected in the case of sub-Eddington accretion and present a calculation of a quantitative estimate, which is very consistent with the effect observed in Her X-1.We urge that Her X-1 is regularly monitored further and that other X-ray pulsars are investigated for a similar behaviour.Comment: 4 pages, 2 figures, accepted by A&A Letter

Multiple Cyclotron Lines in the Spectrum of 4U 0115+63

We report phase resolved spectroscopy of the transient accreting pulsar, 4U0115+63. For the first time, more than two cylotron resonance scattering features are detected in the spectrum of an X-ray pulsar. The shape of the fundamental line appears to be complex, and this is in agreement with predictions of Monte-Carlo models. As in other pulsars, the line energies and optical depths are strong functions of pulse phase. One possible model for this is an offset of the dipole of the neutron star magnetic field.Comment: 5 pages. To appear in "Proceedings of the 5th Compton Symposium

Discovery of a Cyclotron Resonance Scattering Feature in the X-ray Spectrum of XTE J1946+274

Observations of the transient accreting pulsar XTE J1946+274 made with the Rossi X-ray Timing Explorer during the course of the 1998 September-November outburst, reveal a cyclotron resonance scattering feature (or "cyclotron line") in the hard X-ray spectrum near 35 keV. We determine a centroid energy of 36.2 +0.5/-0.7 keV, which implies a magnetic field strength of 3.1(1+z)x10^12 G, where z is the gravitational redshift of the scattering region. The optical depth, Tau = 0.33 +0.07/-0.06, and width, sigma = 3.37 +0.92/-0.75 keV, are typical of known cyclotron lines in other pulsars. This discovery makes XTE J1946+274 one of thirteen pulsars with securely detected cyclotron lines resulting in direct magnetic field measurements.Comment: Five pages including four postscript figures and two tables. Uses emulateapj5. Published in ApJ Letters: http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001ApJ...563L..35

Discovery of a Transition to Global Spin-up in EXO 2030+375

EXO 2030+375, a 42-second transient X-ray pulsar with a Be star companion, has been observed to undergo an outburst at nearly every periastron passage for the last 13.5 years. From 1994 through 2002, the global trend in the pulsar spin frequency was spin-down. Using RXTE data from 2003 September, we have observed a transition to global spin-up in EXO 2030+375. Although the spin frequency observations are sparse, the relative spin-up between 2002 June and 2003 September observations, along with an overall brightening of the outbursts since mid 2002 observed with the RXTE ASM, accompanied by an increase in density of the Be disk, indicated by infrared magnitudes, suggest that the pattern observed with BATSE of a roughly constant spin frequency, followed by spin-up, followed by spin-down is repeating. If so this pattern has approximately an 11 year period, similar to the 15 +/- 3 year period derived by Wilson et al. (2002) for the precession period of a one-armed oscillation in the Be disk. If this pattern is indeed repeating, we predict a transition from spin-up to spin-down in 2005.Comment: Accepted for publication in ApJ Letters, 4 pages, 5 figures, using emulateapj.cl

Optical Modelling of the HFI Instrument on Board the Planck Surveyor

The PLANCK SURVEYOR is a European Space Agency satellite mission to image the very faint anisotropies in the temperature of the Cosmic Microwave Background (CMB) radiation. Maynooth is actively participating in an international collaboration of scientists involved with the optical design of the High Frequency Instrument (HFI). This paper outlines research which has been undertaken in Maynooth concerned with numerical modelling of the optical characteristics of the multi-frequency array of detectors making up the HFI instrument. In the study the commercial software package ZEMAX was used to model the coupling of the focal plane HFI detectors to the PLANCK telescope. This package is particularly useful in the optical design of PLANCK because of the powerful optimisation features of the software. It is thus possible to readily determine the optimum positioning of the detectors in the focal plane of the telescope. Although the package is based on a numerical ray tracing approach, diffraction effects can be included making it possible to model the beam patterns for the HFI array on the sky. As a method of validating this approach the results of the ZEMAX model of the system were compared with that of a more rigorous physical optics simulation. It was concluded from the study that the level of agreement between the two approaches support the proposed use of ZEMAX. Once the detector positions were optimised using ZEMAX the physical optics approach was used to determine a more accurate set of beam patterns for the array

Rural Adults Delay, Forego, and Strategize to Afford Their Pre-ACA Health Care

About 40% of non-elderly adults reported problems paying medical bills or cost-related barriers to obtaining needed medical care in 2012, difficulties that are especially pronounced for the uninsured and underinsured, the chronically-ill, and those with low incomes. Given their lower incomes and higher uninsured rates compared to urban residents, rural residents may face particular cost barriers in accessing health care. Past research has shown that, compared to urban residents, rural residents are more likely to experience higher out-of-pocket costs and delayed or foregone care as a result of cost, even when covered by private health insurance. This study provides detailed information about rural-urban differences among adults under age 65 in perceived affordability of health insurance coverage and services prior to implementation of the Affordable Care Act. Rural adults were more likely than urban adults to report problems paying their medical bills and to delay or forego needed care because of cost. To control costs, rural adults were more likely to skip medication doses, take less medicine, delay filling prescriptions, or ask their physician for a lower cost prescription than urban adults

Rural Disabled Medicare Beneficiaries Spend More out-of-Pocket Than Their Urban Counterparts

The majority of Medicare beneficiaries experience gaps between the care they need and costs covered by Medicare and seek supplemental coverage to meet this gap, including private plans offered by former employers or purchased individually, or public coverage through Medicaid. Since rural beneficiaries are more likely to purchase supplemental indemnity coverage individually, to participate in Medicaid, or to go without supplemental coverage altogether, it is likely that their out-of-pocket spending differs from that of urban residents, although the magnitude and direction of these differences may vary for individual beneficiaries. This study used data from the 2006-2010 Medical Expenditure Panel Survey to evaluate rural-urban differences in out-of-pocket spending, supplemental coverage, and variation in spending by type of service. The proportion of total spending paid out-of-pocket is 40% higher among rural disabled Medicare beneficiaries compared to urban disabled beneficiaries. Rural disabled and elderly beneficiaries are more likely to go without any form of supplemental coverage than urban beneficiaries