The dual-frequency scatterometer reexamined

The utility of dual frequency scatterometers in measuring ocean wave directional spectra can be increased by adding third frequency to the system. The background which effectively limits signal detectability in dual frequency operation can be made a part of the signal through the addition of this third frequency. Signal detectability is limited only by system thermal noise and space based operation becomes more feasible

Barefoot running improves economy at high intensities and peak treadmill velocity

Aim: Barefoot running can improve running economy (RE) compared to shod running at low exercise intensities, but data is lacking for the higher intensities typical during many distance running competitions. The influence of barefoot running on the velocity at maximal oxygen uptake (vVO2max) and peak incremental treadmill test velocity (vmax) is unknown. The present study tested the hypotheses that barefoot running would improve RE, vVO2max and vmax relative to shod running. Methods: Using a balanced within-subject repeated measures design, eight male runners (aged 23.1±4.5 years, height 1.80±0.06 m, mass 73.8±11.5 kg, VO2max 4.08±0.39 L·min-1) completed a familiarization followed by one barefoot and one shod treadmill running trial, 2-14 days apart. Trial sessions consisted of a 5 minute warm-up, 5 minute rest, followed by 4×4 minute stages, at speeds corresponding to ~67, 75, 84 and 91% shod VO2max respectively, separated by a 1 minute rest. After the 4th stage treadmill speed was incremented by 0.1 km·h-1 every 15 s until participants reached volitional exhaustion. Results: RE was improved by 4.4±7.0% across intensities in the barefoot condition (P=0.040). The improvement in RE was related to removed shoe mass (r2=0.80, P=0.003) with an intercept at 0% improvement for RE at 0.520 kg total shoe mass. Both vVO2max (by 4.5±5.0%, P=0.048) and vmax (by 3.9±4.0%, P=0.030) also improved but VO2max was unchanged (p=0.747). Conclusion: Barefoot running improves RE at high exercise intensities and increases vVO2max and vmax, but further research is required to clarify the influence of very light shoe weights on RE

An outburst scenario for the X-ray spectral variability in 3C 111

We present a combined Suzaku and Swift BAT broad-band E=0.6-200keV spectral analysis of three 3C 111 observations obtained in 2010. The data are well described with an absorbed power-law continuum and a weak (R~0.2) cold reflection component from distant material. We constrain the continuum cutoff at E_c~150-200keV, which is in accordance with X-ray Comptonization corona models and supports claims that the jet emission is only dominant at much higher energies. Fe XXVI Ly\alpha emission and absorption lines are also present in the first and second observations, respectively. The modelling and interpretation of the emission line is complex and we explore three possibilities. If originating from ionized disc reflection, this should be emitted at r_in> 50r_g or, in the lamp-post configuration, the illuminating source should be at a height of h> 30r_g over the black hole. Alternatively, the line could be modeled with a hot collisionally ionized plasma with temperature kT = 22.0^{+6.1}_{-3.2} keV or a photo-ionized plasma with log\xi=4.52^{+0.10}_{-0.16} erg s^{-1} cm and column density N_H > 3x10^23 cm^{-2}. However, the first and second scenarios are less favored on statistical and physical grounds, respectively. The blue-shifted absorption line in the second observation can be modelled as an ultra-fast outflow (UFO) with ionization parameter log\xi=4.47^{+0.76}_{-0.04} erg s^{-1} cm, column density N_H=(5.3^{+1.8}_{-1.3})x 10^{22} cm^{-2} and outflow velocity v_out = 0.104+/-0.006 c. Interestingly, the parameters of the photo-ionized emission model remarkably match those of the absorbing UFO. We suggest an outburst scenario in which an accretion disc wind, initially lying out of the line of sight and observed in emission, then crosses our view to the source and it is observed in absorption as a mildly-relativistic UFO.Comment: Accepted for publication in MNARS on July 1st 201

An XMM-Newton observation of the Narrow Line Seyfert 1 Galaxy, Markarian 896

XMM-Newton observations of the NLS1 Markarian 896 are presented. Over the 2-10 keV band, an iron emission line, close to 6.4 keV, is seen. The line is just resolved and has an equivalent width of ~170 eV. The broad-band spectrum is well modelled by a power law slope of gamma ~ 2.03, together with two blackbody components to fit the soft X-ray excess. Using a more physical two-temperature Comptonisation model, a good fit is obtained for an input photon distribution of kT ~ 60eV and Comptonising electron temperatures of ~0.3 and 200 keV. The soft excess cannot be explained purely through the reprocessing of a hard X-ray continuum by an ionised disc reflector.Comment: 6 pages, 4 figures, accepted by MNRA

X-ray variability analysis of a large series of XMM-Newton + NuSTAR observations of NGC 3227

We present a series of X-ray variability results from a long XMM-Newton + NuSTAR campaign on the bright, variable AGN NGC 3227. We present an analysis of the lightcurves, showing that the source displays typically softer-when-brighter behaviour, although also undergoes significant spectral hardening during one observation which we interpret as due to an occultation event by a cloud of absorbing gas. We spectrally decompose the data and show that the bulk of the variability is continuum-driven and, through rms variability analysis, strongly enhanced in the soft band. We show that the source largely conforms to linear rms-flux behaviour and we compute X-ray power spectra, detecting moderate evidence for a bend in the power spectrum, consistent with existing scaling relations. Additionally, we compute X-ray Fourier time lags using both the XMM-Newton and - through maximum-likelihood methods - NuSTAR data, revealing a strong low-frequency hard lag and evidence for a soft lag at higher frequencies, which we discuss in terms of reverberation models.Comment: Accepted for publication in MNRAS; 19 pages, 13 figures, 4 tables; minor typographical errors corrected and reference list update