The alpha-effect in rotating convection: a comparison of numerical simulations

Numerical simulations are an important tool in furthering our understanding of turbulent dynamo action, a process that occurs in a vast range of astrophysical bodies. It is important in all computational work that comparisons are made between different codes and, if non-trivial differences arise, that these are explained. Kapyla et al (2010: MNRAS 402, 1458) describe an attempt to reproduce the results of Hughes & Proctor (2009: PRL 102, 044501) and, by employing a different methodology, they arrive at very different conclusions concerning the mean electromotive force and the generation of large-scale fields. Here we describe why the simulations of Kapyla et al (2010) are simply not suitable for a meaningful comparison, since they solve different equations, at different parameter values and with different boundary conditions. Furthermore we describe why the interpretation of Kapyla et al (2010) of the calculation of the alpha-effect is inappropriate and argue that the generation of large-scale magnetic fields by turbulent convection remains a problematic issue.Comment: Submitted to MNRAS. 5 pages, 3 figure

Plane-wave impulse approximation extraction of the neutron magnetic form factor from quasielastic ^3He(e,e') at Q^2=0.3 to 0.6 (GeV/c)^2

A high precision measurement of the transverse spin-dependent asymmetry A_T' in ^3He(e,e') quasielastic scattering was performed in Hall A at Jefferson Lab at values of the squared four-momentum transfer, Q^2, between 0.1 and 0.6 (GeV/c)^2. A_(T') is sensitive to the neutron magnetic form factor, G_M^n . Values of G_M^n at Q^2 = 0.1 and 0.2 (GeV/c)^2, extracted using Faddeev calculations, were reported previously. Here, we report the extraction of G_M^n for the remaining Q^2 values in the range from 0.3 to 0.6 (GeV/c)^2 using a plane-wave impulse approximation calculation. The results are in good agreement with recent precision data from experiments using a deuterium target

Q^2 Evolution of the Neutron Spin Structure Moments using a ^3He Target

We have measured the spin structure functions g_1 and g_2 of ^3He in a double-spin experiment by inclusively scattering polarized electrons at energies ranging from 0.862 to 5.058 GeV off a polarized ^3He target at a 15.5° scattering angle. Excitation energies covered the resonance and the onset of the deep inelastic regions. We have determined for the first time the Q^2 evolution of Γ_1(Q^2)=∫_0^1g_1(x,Q^2)dx, Γ_2(Q^2)=∫_0^1g_2(x,Q^2)dx, and d_2(Q^2)=∫_0^1x^2[2g_1(x,Q^2)+3g_2(x,Q^2)]dx for the neutron in the range 0.1 ≤ Q^2 ≤0.9  GeV^2 with good precision. Γ_1(Q^2) displays a smooth variation from high to low Q^2. The Burkhardt-Cottingham sum rule holds within uncertainties and d_2 is nonzero over the measured range

Precision Measurement of the Spin-Dependent Asymmetry in the Threshold Region of ^3He(e, e')

We present the first precision measurement of the spin-dependent asymmetry in the threshold region of ^3He(e,e′) at Q^2 values of 0.1 and 0.2(GeV/c)^2. The agreement between the data and nonrelativistic Faddeev calculations which include both final-state interactions and meson-exchange current effects is very good at Q^2 = 0.1(GeV/c)^2, while a small discrepancy at Q^2 = 0.2(GeV/c)^2 is observed

Q^2 Evolution of the Generalized Gerasimov-Drell-Hearn Integral for the Neutron using a ^3He Target

We present data on the inclusive scattering of polarized electrons from a polarized ^3He target at energies from 0.862 to 5.06 GeV, obtained at a scattering angle of 15.5°. Our data include measurements from the quasielastic peak, through the nucleon resonance region, and beyond, and were used to determine the virtual photon cross-section difference σ_(1/2)-σ_(3/2). We extract the extended Gerasimov-Drell-Hearn integral for the neutron in the range of four-momentum transfer squared Q^2 of 0.1–0.9   GeV^2

Transverse Asymmetry A_T′ from the Quasielastic ^3He(e,e′) Process and the Neutron Magnetic Form Factor

We have measured the transverse asymmetry A_T′ in ^3He(e,e′) quasielastic scattering in Hall A at Jefferson Laboratory with high precision for Q^2 values from 0.1 to 0.6 (GeV/c)^2. The neutron magnetic form factor GMn was extracted based on Faddeev calculations for Q^2 = 0.1 and 0.2 (GeV/c)^2 with an experimental uncertainty of less than 2%

Observation of Parity Nonconservation in Møller Scattering

We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A_(PV) = [-175 ± 30(stat)± 20(syst)] X 10^(-9). This first direct observation of parity nonconservation in Møller scattering leads to a measurement of the electron’s weak charge at low energy Q^e_W = -0:053 ± 0:011. This is consistent with the standard model expectation at the current level of precision: sin^2θ_W = (M_Z)_(MS) = 0:2293 ± 0:0024(stat) ± 0:0016(syst) ± 0:0006(theory)

A Novel, Contactless, Portable “Spot-Check” Device Accurately Measures Respiratory Rate

Respiratory rate (RR) is an important vital sign used in the assessment of acutely ill patients. It is also used as to predict serious deterioration in a patient's clinical condition. Convenient electronic devices exist for measurement of pulse, blood pressure, oxygen saturation and temperature. Although devices which measure RR exist, none has entered everyday clinical practice. We developed a contactless portable respiratory rate monitor (CPRM) and evaluated the agreement in respiratory rate measurements between existing methods and our new device. The CPRM uses thermal anemometry to measure breath signals during inspiration and expiration. RR data were collected from 52 healthy adult volunteers using respiratory inductance plethysmography (RIP) bands (established contact method), visual counting of chest movements (established non-contact method) and the CPRM (new method), simultaneously. Two differently shaped funnel attachments were evaluated for each volunteer. Data showed good agreement between measurements from the CPRM and the gold standard RIP, with intra-class correlation coefficient (ICC): 0.836, mean difference 0.46 and 95% limits of agreement of -5.90 to 6.83. When separate air inlet funnels of the CPRM were analysed, stronger agreement was seen with an elliptical air inlet; ICC 0.908, mean difference 0.37 with 95% limits of agreement -4.35 to 5.08. A contactless device for accurately and quickly measuring respiratory rate will be an important triage tool in the clinical assessment of patients. More testing is needed to explore the reasons for outlying measurements and to evaluate in the clinical setting