Thermal enhancement of magnetic susceptibility

The interpretation of geomagnetic anomalies with deep-seated sources sometimes requires postulating magnetic susceptibilities larger than those measured for common rock types at the Earth's surface. A possible explanation is that rocks buried at depths approaching the Curie point isotherm exhibit enhanced susceptibility due to the Hopkinson effect. In measurements on a sample of single-domain magnetite (0.04 μm particles), the susceptibility increased by a factor 2 between 20 and 500 °C and by a factor 3 at 550 °C. The Hopkinson peak was less pronounced in multidomain magnetites: the relative increase in susceptibility at 550 °C was by a factor 2 in 0.1 μm particles and a factor 1.5 in 0.25 μm particles. Single-domain hematite (0.1–1 μm) gave a spectacular Hopkinson peak, with relative susceptibility enhancement by a factor 5 at 530 °C and a factor 20 at 640 °C. However, rocks containing fine-grained maghemite and magnetite showed an enhancement of 50–70 % at most. The reasons for this variability in the height of the Hopkinson peak are not understood, but the width and shape of the peak are clearly related to the blocking temperature spectrum. Distributed blocking temperatures are associated with a broad peak, while discrete blocking temperatures are accompanied by a sharp susceptibility peak within 50-100 °C of the Curie point. A corollary is that remanent magnetization decreases roughly in inverse proportion to increase in susceptibility, so that the Koenigsberger Qn ratio decreases sharply at high temperature. For this reason, deep-seated anomalies can almost certainly be interpreted in terms of induced magnetization only. Finally, somewhat shallower bodies (temperatures of 200–400 °C) may exhibit thermally enhanced magnetization for two reasons: first, titanomagnetites have widely varying Curie points depending on titanium content, and second, observed anomalies are the result of a geomagnetic field applied over 106 years and viscous magnetization is also known to be enhanced at high temperature.           ARK: https://n2t.net/ark:/88439/y022154 Permalink: https://geophysicsjournal.com/article/162 &nbsp

A bio-economic analysis of harvest control rules for the Northeast Arctic cod fishery

Harvest control rules (HCRs) have been implemented for many fisheries worldwide. However, in most instances, those HCRs are not based on the explicit feedbacks between stock properties and economic considerations. This paper develops a bio-economic model that evaluates the HCR adopted in 2004 by the Joint Norwegian-Russian Fishery Commission to manage the world's largest cod stock, Northeast Arctic cod (NEA). The model considered here is biologically and economically detailed, and is the firt to compare the performance of the stock's current HCR with that of alternative HCRs derived with optimality criteria. In particular, HCRs are optimized for economic objectives including fleet profit, economic welfare, and total yield and the emerging properties are analyzed. The performance of these optimal HCRs was compared with the currently used HCR. This paper show that the current HCR does in fact comes very close to maximizing profits. Furthermore, the results reveal that the HCR that maximizes profits is the most precautionary one among the considered HCRs. Finally, the HCR that maximizes yield leads to un-precautionary low levels of biomass. In these ways, the implementation of the HCR for NEA cod can be viewed as a success story that may provide valuable lessons for other fishries

A note on brain actuated spelling with the Berlin brain-computer interface

Brain-Computer Interfaces (BCIs) are systems capable of decoding neural activity in real time, thereby allowing a computer application to be directly controlled by the brain. Since the characteristics of such direct brain-tocomputer interaction are limited in several aspects, one major challenge in BCI research is intelligent front-end design. Here we present the mental text entry application ‘Hex-o-Spell’ which incorporates principles of Human-Computer Interaction research into BCI feedback design. The system utilises the high visual display bandwidth to help compensate for the extremely limited control bandwidth which operates with only two mental states, where the timing of the state changes encodes most of the information. The display is visually appealing, and control is robust. The effectiveness and robustness of the interface was demonstrated at the CeBIT 2006 (world’s largest IT fair) where two subjects operated the mental text entry system at a speed of up to 7.6 char/min

Still Misinterpreting Lie Scales: Reply to Feldman’s Rejoinder

Despite convincing counterevidence, misinterpretation of so-called Impression Management, Social Desirability, or Lie scales in low-stakes settings seems to persist. In this reply to an ongoing discussion with Feldman and colleagues (De Vries et al., 2017; Feldman, in press; Feldman et al., 2017), we argue that high scores on Impression Management and Lie scales in low-stakes settings are more likely to reflect honesty than dishonesty. Specifically, we point out (1) that there is no evidence of a relation between Impression Management and (in-)authenticity, (2) that respondents in anonymous online studies have no reason to be inauthentic, and (3) that laypersons’ judgments about Lie scale responses (especially responses that are extremely rare) are uninformative and thus yield no insight on the construct validity of the Lie scale. We finally reiterate the warning that conclusions based on the incorrect interpretation of Impression Management, Social Desirability, or Lie scales in low-stakes settings are invalid

Risk factors for failure of the 36 mm metal-on-metal Pinnacle total hip arthroplasty system:a retrospective single-centre cohort study

Aims: To determine 10-year failure rates following 36mm metal-on-metal (MoM) Pinnacle total hip replacement (THR), and identify predictors of failure. Methods: We retrospectively assessed a single-centre cohort of 569 primary 36mm MoM Pinnacle THRs (all Corail stems) followed up since 2012 according to MHRA recommendations. Allcause failure rates (all-cause revision, and non-revised cross-sectional imaging failures) were calculated, with predictors for failure identified using multivariable Cox regression. Results: Failure occurred in 97 hips (17.0%). The 10-year cumulative failure rate was 27.1% (95% CI=21.6%-33.7%). Primary implantation from 2006 onwards (Hazard Ratio (HR)=4.30; CI=1.82-10.1; p=0.001) and bilateral MoM hip arthroplasty (HR=1.59; CI=1.03-2.46; p=0.037) predicted failure. The effect of implantation year on failure varied over time. From 4-years onwards following surgery, hips implanted since 2006 had significantly higher failure rates (8-years=28.3%; CI=23.1%-34.5%) compared to hips implanted before 2006 (8- years=6.3%; CI=2.4%-15.8%) (HR=15.2; CI=2.11-110.4; p=0.007). Conclusion: We observed that 36mm MoM Pinnacle THRs have an unacceptably high 10-year failure rate, especially if implanted from 2006 onwards or in bilateral MoM patients. Our findings regarding implantation year and failure support recent concerns about the device manufacturing process. We recommend all patients undergoing implantation since 2006 and those with bilateral MoM hips undergo regular investigation, regardless of symptoms

Combined constraints on modified Chaplygin gas model from cosmological observed data: Markov Chain Monte Carlo approach

We use the Markov Chain Monte Carlo method to investigate a global constraints on the modified Chaplygin gas (MCG) model as the unification of dark matter and dark energy from the latest observational data: the Union2 dataset of type supernovae Ia (SNIa), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the cosmic microwave background (CMB) data. In a flat universe, the constraint results for MCG model are, $\Omega_{b}h^{2}=0.02263^{+0.00184}_{-0.00162}$ ($1\sigma$) $^{+0.00213}_{-0.00195}$ $(2\sigma)$, $B_{s}=0.7788^{+0.0736}_{-0.0723}$ ($1\sigma$) $^{+0.0918}_{-0.0904}$ $(2\sigma)$, $\alpha=0.1079^{+0.3397}_{-0.2539}$ ($1\sigma$) $^{+0.4678}_{-0.2911}$ $(2\sigma)$, $B=0.00189^{+0.00583}_{-0.00756}$ ($1\sigma$) $^{+0.00660}_{-0.00915}$ $(2\sigma)$, and $H_{0}=70.711^{+4.188}_{-3.142}$ ($1\sigma$) $^{+5.281}_{-4.149}$ $(2\sigma)$.Comment: 12 pages, 1figur

Does accelerating universe indicates Brans-Dicke theory

The evolution of universe in Brans-Dicke (BD) theory is discussed in this paper. Considering a parameterized scenario for BD scalar field $\phi=\phi_{0}a^{\alpha}$ which plays the role of gravitational "constant" $G$, we apply the Markov Chain Monte Carlo method to investigate a global constraints on BD theory with a self-interacting potential according to the current observational data: Union2 dataset of type supernovae Ia (SNIa), high-redshift Gamma-Ray Bursts (GRBs) data, observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the cosmic microwave background (CMB) data. It is shown that an expanded universe from deceleration to acceleration is given in this theory, and the constraint results of dimensionless matter density $\Omega_{0m}$ and parameter $\alpha$ are, $\Omega_{0m}=0.286^{+0.037+0.050}_{-0.039-0.047}$ and $\alpha=0.0046^{+0.0149+0.0171}_{-0.0171-0.0206}$ which is consistent with the result of current experiment exploration, $\mid\alpha\mid \leq 0.132124$. In addition, we use the geometrical diagnostic method, jerk parameter $j$, to distinguish the BD theory and cosmological constant model in Einstein's theory of general relativity.Comment: 16 pages, 3 figure

Improved constraints on the expansion rate of the Universe up to z~1.1 from the spectroscopic evolution of cosmic chronometers

We present new improved constraints on the Hubble parameter H(z) in the redshift range 0.15 < z < 1.1, obtained from the differential spectroscopic evolution of early-type galaxies as a function of redshift. We extract a large sample of early-type galaxies (\sim11000) from several spectroscopic surveys, spanning almost 8 billion years of cosmic lookback time (0.15 < z < 1.42). We select the most massive, red elliptical galaxies, passively evolving and without signature of ongoing star formation. Those galaxies can be used as standard cosmic chronometers, as firstly proposed by Jimenez & Loeb (2002), whose differential age evolution as a function of cosmic time directly probes H(z). We analyze the 4000 {\AA} break (D4000) as a function of redshift, use stellar population synthesis models to theoretically calibrate the dependence of the differential age evolution on the differential D4000, and estimate the Hubble parameter taking into account both statistical and systematical errors. We provide 8 new measurements of H(z) (see Tab. 4), and determine its change in H(z) to a precision of 5-12% mapping homogeneously the redshift range up to z \sim 1.1; for the first time, we place a constraint on H(z) at z \neq 0 with a precision comparable with the one achieved for the Hubble constant (about 5-6% at z \sim 0.2), and covered a redshift range (0.5 < z < 0.8) which is crucial to distinguish many different quintessence cosmologies. These measurements have been tested to best match a \Lambda CDM model, clearly providing a statistically robust indication that the Universe is undergoing an accelerated expansion. This method shows the potentiality to open a new avenue in constrain a variety of alternative cosmologies, especially when future surveys (e.g. Euclid) will open the possibility to extend it up to z \sim 2.Comment: 34 pages, 15 figures, 6 tables, published in JCAP. It is a companion to Moresco et al. (2012b, http://arxiv.org/abs/1201.6658) and Jimenez et al. (2012, http://arxiv.org/abs/1201.3608). The H(z) data can be downloaded at http://www.physics-astronomy.unibo.it/en/research/areas/astrophysics/cosmology-with-cosmic-chronometer

Single Spin Asymmetry ANA_N in Polarized Proton-Proton Elastic Scattering at s=200\sqrt{s}=200 GeV

We report a high precision measurement of the transverse single spin asymmetry $A_N$ at the center of mass energy $\sqrt{s}=200$ GeV in elastic proton-proton scattering by the STAR experiment at RHIC. The $A_N$ was measured in the four-momentum transfer squared $t$ range $0.003 \leqslant |t| \leqslant 0.035$ \GeVcSq, the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of $A_N$ and its $t$-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this $\sqrt{s}$, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton-proton elastic scattering.Comment: 12 pages, 6 figure

Longitudinal double-spin asymmetry and cross section for inclusive neutral pion production at midrapidity in polarized proton collisions at sqrt(s) = 200 GeV

We report a measurement of the longitudinal double-spin asymmetry A_LL and the differential cross section for inclusive Pi0 production at midrapidity in polarized proton collisions at sqrt(s) = 200 GeV. The cross section was measured over a transverse momentum range of 1 < p_T < 17 GeV/c and found to be in good agreement with a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry was measured in the range of 3.7 < p_T < 11 GeV/c and excludes a maximal positive gluon polarization in the proton. The mean transverse momentum fraction of Pi0's in their parent jets was found to be around 0.7 for electromagnetically triggered events.Comment: 6 pages, 3 figures, submitted to Phys. Rev. D (RC