On the population of remnant FRII radio galaxies and implications for radio source dynamics

The purpose of this work is two-fold: (1) to quantify the occurrence of ultra-steep spectrum remnant FRII radio galaxies in a 74 MHz flux limited sample, and (2) perform Monte-Carlo simulations of the population of active and remnant FRII radio galaxies to confront models of remnant lobe evolution, and provide guidance for further investigation of remnant radio galaxies. We find that fewer than 2$\%$ of FRII radio galaxies with S$_{ \rm74~MHz} > 1.5$ Jy are candidate ultra-steep spectrum remnants, where we define ultra-steep spectrum as $\alpha_{\rm 74~MHz}^{\rm 1400~MHz} > 1.2$. Our Monte-Carlo simulations demonstrate that models involving Sedov-like expansion in the remnant phase, resulting in rapid adiabatic energy losses, are consistent with this upper limit, and predict the existence of nearly twice as many remnants with normal (not ultra-steep) spectra in the observed frequency range as there are ultra-steep spectrum remnants. This model also predicts an ultra-steep remnant fraction approaching 10$\%$ at redshifts $z < 0.5$. Importantly, this model implies the lobes remain over-pressured with respect to the ambient medium well after their active lifetime, in contrast with existing observational evidence that many FRII radio galaxy lobes reach pressure equilibrium with the external medium whilst still in the active phase. The predicted age distribution of remnants is a steeply decreasing function of age. In other words young remnants are expected to be much more common than old remnants in flux limited samples. For this reason, incorporating higher frequency data $\gtrsim 5$ GHz will be of great benefit to future studies of the remnant population.Comment: 19 pages, 8 figures, 4 table

Properties of the Strange Axial Mesons in the Relativized Quark Model

We studied properties of the strange axial mesons in the relativized quark model. We calculated the $K_1$ decay constant in the quark model and showed how it can be used to extract the $K_1 (^3P_1) - K_1 (^1P_1)$ mixing angle ($\theta_K$) from the weak decay $\tau \to K_1 \nu_\tau$. The ratio $BR(\tau \to \nu_\tau K_1 (1270))/BR(\tau\to \nu_\tau K_1(1400))$ is the most sensitive measurement and also the most reliable since the largest of the theoretical uncertainties factor out. However the current bounds extracted from the TPC/Two-Gamma collaboration measurements are rather weak: we typically obtain $-30^o \lesssim \theta_K \lesssim 50^o$ at 68\% C.L. We also calculated the strong OZI-allowed decays in the pseudoscalar emission model and the flux-tube breaking model and extracted a $^3P_1 - ^1P_1$ mixing angle of $\theta_K \simeq 45^o$. Our analysis also indicates that the heavy quark limit does not give a good description of the strange mesons.Comment: Revised version to be published in Phys. Rev. D. Minor changes. Latex file uses revtex version 3 and epsfig, 4 postcript figures are attached. The full postcript version with embedded figures is available at ftp://ftp.physics.carleton.ca/pub/theory/godfrey/ocipc9512.ps.

Quartz crystal microbalance use in biological studies

Design, development, and applications of quartz crystal microbalance are discussed. Two types of crystals are used. One serves as reference and other senses changes in mass. Specific application to study of bacterial spores is described

Regarding the axial-vector mesons

The implications of the $f_1(1285)-f_1(1420)$ mixing for the $K_1(^3P_1)-K_1(^1P_1)$ mixing angle is investigated. Based on the $f_1(1285)-f_1(1420)$ mixing angle $\sim 50^\circ$ suggested from the analysis for a substantial body of data concerning the $f_1(1420)$ and $f_1(1285)$, the masses of the $K_1(^3P_1)$ and $K_1(^1P_1)$ are determined to be $\sim 1307.35\pm 0.63$ MeV and $1370.03\pm 9.69$ MeV, respectively, which therefore suggests that the $K_1(^3P_1)-K_1(^1P_1)$ mixing angle is about $\pm (59.55\pm 2.81)^\circ$. Also, it is found that the mass of the $h^\prime_1(^1P_1)$ (mostly of $s\bar{s}$) state is about $1495.18\pm 8.82$ MeV. Comparison of the predicted results and the available experimental information of the $h_1(1380)$ shows that without further confirmation on the $h_1(1380)$, the assignment of the $h_1(1380)$ as the $s\bar{s}$ member of the $^1P_1$ meson nonet may be premature.Comment: 11 pages, some typos corrected, accepted for publication in Eur. Phys. J.

Laboratory Measurement of the Pure Rotational Transitions of the HCNH+ and its Isotopic Species

The pure rotational transitions of the protonated hydrogen cyanide ion, HCNH+, and its isotopic species, HCND+ and DCND+, were measured in the 107 - 482 GHz region with a source modulated microwave spectrometer. The ions were generated in the cell with a magnetically confined dc-glow discharge of HCN and/or DCN. The rotational constant B0 and the centrifugal distortion constant D0 for each ion were precisely determined by a least-squares fitting to the observed spectral lines. The observed rotational transition frequencies by laboratory spectroscopy and the predicted ones are accurate in about 30 to 40 kHz and are useful as rest frequencies for astronomical searches of HCNH+ and HCND+.Comment: 14 pages in TeX, 1 figures in JPE

Strong Decays of Strange Charmed P-Wave Mesons

Goldstone boson decays of P-wave $D_s^{**}$ mesons are studied within the framework of Heavy Hadron Chiral Perturbation Theory. We first analyze the simplest single kaon decays of these strange charmed mesons. We derive a model independent prediction for the width of $D_{s2}$ and use experimental information on $D_{s1}$ to constrain the S-wave contribution to $D_1^0$ decay. Single and double pion decay modes are then discussed and shown to be significantly restricted by isospin conservation. We conclude that the pion channels may offer the best hope for detecting one strange member of an otherwise invisible P-wave flavor multiplet.Comment: 16 pages, 2 updated figures not included but available upon request, CALT-68-1902. (Revised estimates for error on $D_{s2}$ width and for isospin violating neutral pion decay of $D'_{s1}$.

Water, Sanitation, and Hygiene: Linkages with Stunting in Rural Ethiopia

Stunting is a global burden affecting nearly 160 million children younger than five years of age. Whilst the linkages between nutrition and stunting are well recognized, there is a need to explore environmental factors such as water and sanitation, which may influence feeding practices and result in potential infection pathways. This paper explores the linkages between stunting and water, sanitation and hygiene (WASH) factors in Ethiopia, which is a relatively understudied context. The research draws upon baseline data for children under the age of five from 3200 households across four regions in Ethiopia as part of a wider study and integrated program led by the United Nations Children’s Fund (UNICEF). Using World Health Organization (WHO) z-scoring, the average stunting rate in the sample is 47.5%. This paper also takes into account demographic and social behavioural factors such as the age, gender of children, and gender of the primary caregiver, in addition to handwashing behaviour and drinking water facilities. The evidence recommends efforts to improve handwashing behaviour for mothers and children with a focus on access to clean water. Higher stunting rates with an increase in the age of children highlight the need for continued interventions, as efforts to improve nutrition and WASH behaviours are most effective early on in promoting long-term health outcomes for children

Acidosis slows electrical conduction through the atrio-ventricular node

Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN). In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode's solution (20% CO2, pH 6.7) increased the time of earliest activation (Tact) from 100.5 ± 7.9 to 166.1 ± 7.2 ms (n = 8) at a pacing cycle length (PCL) of 300 ms (37°C). Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150 ms PCL, Tact was prolonged from 131.0 ± 5.2 to 174.9 ± 16.3 ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode's solutions at pH 7.4 (control), 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH) interval, the AVN effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis

A Multi-Wavelength Study of the Jet, Lobes and Core of the Quasar PKS 2101-490

We present a detailed study of the X-ray, optical and radio emission from the jet, lobes and core of the quasar PKS 2101-490 as revealed by new Chandra, HST and ATCA images. We extract the radio to X-ray spectral energy distributions from seven regions of the 13 arcsecond jet, and model the jet X-ray emission in terms of Doppler beamed inverse Compton scattering of the cosmic microwave background (IC/CMB) for a jet in a state of equipartition between particle and magnetic field energy densities. This model implies that the jet remains highly relativistic hundreds of kpc from the nucleus, with a bulk Lorentz factor Gamma ~ 6 and magnetic field of order 30 microGauss. We detect an apparent radiative cooling break in the synchrotron spectrum of one of the jet knots, and are able to interpret this in terms of a standard one-zone continuous injection model, based on jet parameters derived from the IC/CMB model. However, we note apparent substructure in the bright optical knot in one of the HST bands. We confront the IC/CMB model with independent estimates of the jet power, and find that the IC/CMB model jet power is consistent with the independent estimates, provided that the minimum electron Lorentz factor gamma_min > 50, and the knots are significantly longer than the jet width, as implied by de-projection of the observed knot lengths.Comment: 16 pages, 10 figures, 6 table