Geometry of Keplerian disk systems and bounds on masses of their components

We investigate accreting disk systems with polytropic gas in Keplerian motion. Numerical data and partial analytic results show that the self-gravitation of the disk speeds up its rotation -- its rotational frequency is larger than that given by the well known strictly Keplerian formula that takes into account the central mass only. Thus determination of central mass in systems with massive disks requires great care -- the strictly Keplerian formula yields only an upper bound. The effect of self-gravity depends on geometric aspects of disk configurations. Disk systems with a small (circa $10^{-4}$) ratio of the innermost radius to the outermost disk radius have the central mass close to the upper limit, but if this ratio is of the order of unity then the central mass can be smaller by many orders of magnitude from this bound.Comment: 20 pages, 10 figure

Diffusion of the scalar field energy due to the backscattering off Schwarzschild geometry

This note tackles the problem of the backscattering of a mass-less scalar field in the case of Schwarzschildean space-time. It shows that the effect depends both on a distance from the horizon and on the wave length. The obtained estimates significantly improve former results.Comment: LaTeX 2e, 6 page

Modelling Electron Spin Accumulation in a Metallic Nanoparticle

A model describing spin-polarized current via discrete energy levels of a metallic nanoparticle, which has strongly asymmetric tunnel contacts to two ferromagnetic leads, is presented. In absence of spin-relaxation, the model leads to a spin-accumulation in the nanoparticle, a difference ($\Delta\mu$) between the chemical potentials of spin-up and spin-down electrons, proportional to the current and the Julliere's tunnel magnetoresistance. Taking into account an energy dependent spin-relaxation rate $\Omega (\omega)$, $\Delta\mu$ as a function of bias voltage ($V$) exhibits a crossover from linear to a much weaker dependence, when $|e|\Omega (\Delta\mu)$ equals the spin-polarized current through the nanoparticle. Assuming that the spin-relaxation takes place via electron-phonon emission and Elliot-Yafet mechanism, the model leads to a crossover from linear to $V^{1/5}$ dependence. The crossover explains recent measurements of the saturation of the spin-polarized current with $V$ in Aluminum nanoparticles, and leads to the spin-relaxation rate of $\approx 1.6 MHz$ in an Aluminum nanoparticle of diameter $6nm$, for a transition with an energy difference of one level spacing.Comment: 37 pages, 7 figure

Minimal Clinically Important Difference for the Rasch Neuropsychiatric Inventory Irritability and Aggression Scale for Traumatic Brain Injury

Objective To determine the minimal clinically important difference (MCID) for a Rasch measure derived from the Irritability/Lability and Agitation/Aggression subscales of the Neuropsychiatric Inventory (NPI)—the Rasch NPI Irritability and Aggression Scale for Traumatic Brain Injury (NPI-TBI-IA). Design Distribution-based statistical methods were applied to retrospective data to determine candidates for the MCID. These candidates were evaluated by anchoring the NPI-TBI-IA to Global Impression of Change (GIC) ratings by participants, significant others, and a supervising physician. Setting Postacute rehabilitation outpatient clinic. Participants 274 cases with observer ratings; 232 cases with self-ratings by participants with moderate-severe TBI at least 6 months postinjury. Interventions Not applicable. Main Outcome Measure NPI-TBI-IA. Results For observer ratings on the NPI-TBI-IA, anchored comparisons found an improvement of 0.5 SD was associated with at least minimal general improvement on GIC by a significant majority (69%–80%); 0.5 SD improvement on participant NPI-TBI-IA self-ratings was also associated with at least minimal improvement on the GIC by a substantial majority (77%–83%). The percentage indicating significant global improvement did not increase markedly on most ratings at higher levels of improvement on the NPI-TBI-IA. Conclusions A 0.5 SD improvement on the NPI-TBI-IA indicates the MCID for both observer and participant ratings on this measure

Can Schwarzschildean gravitational fields suppress gravitational waves?

Gravitational waves in the linear approximation propagate in the Schwarzschild spacetime similarly as electromagnetic waves. A fraction of the radiation scatters off the curvature of the geometry. The energy of the backscattered part of an initially outgoing pulse of the quadrupole gravitational radiation is estimated by compact formulas depending on the initial energy, the Schwarzschild radius, and the location and width of the pulse. The backscatter becomes negligible in the short wavelength regime.Comment: 18 pages, Revtex. Added three references; a new comment in Sec. 7; several misprints corrected. To appear in the Phys. Rev.

Estimating the Spot Covariation of Asset Prices – Statistical Theory and Empirical Evidence

We propose a new estimator for the spot covariance matrix of a multi-dimensional continuous semimartingale log asset price process which is subject to noise and non-synchronous observations. The estimator is constructed based on a local average of block-wise parametric spectral covariance estimates. The latter originate from a local method of moments (LMM) which recently has been introduced by Bibinger et al. (2014). We extend the LMM estimator to allow for autocorrelated noise and propose a method to adaptively infer the autocorrelations from the data. We prove the consistency and asymptotic normality of the proposed spot covariance estimator. Based on extensive simulations we provide empirical guidance on the optimal implementation of the estimator and apply it to high-frequency data of a cross-section of NASDAQ blue chip stocks. Employing the estimator to estimate spot covariances, correlations and betas in normal but also extreme-event periods yields novel insights into intraday covariance and correlation dynamics. We show that intraday (co-)variations (i) follow underlying periodicity patterns, (ii) reveal substantial intraday variability associated with (co-)variation risk, (iii) are strongly serially correlated, and (iv) can increase strongly and nearly instantaneously if new information arrives

Blowup of Jang's equation at outermost marginally trapped surfaces

The aim of this paper is to collect some facts about the blowup of Jang's equation. First, we discuss how to construct solutions that blow up at an outermost MOTS. Second, we exclude the possibility that there are extra blowup surfaces in data sets with non-positive mean curvature. Then we investigate the rate of convergence of the blowup to a cylinder near a strictly stable MOTS and show exponential convergence near a strictly stable MOTS.Comment: 15 pages. This revision corrects some typo

First constraint on cosmological variation of the proton-to-electron mass ratio from two independent telescopes

A high signal-to-noise spectrum covering the largest number of hydrogen lines (90 H2 lines and 6 HD lines) in a high redshift object was analyzed from an observation along the sight-line to the bright quasar source J2123$-$005 with the UVES spectrograph on the ESO Very Large Telescope (Paranal, Chile). This delivers a constraint on a possible variation of the proton-to-electron mass ratio of Dmu/mu = (8.5 \pm 3.6_{stat} \pm 2.2_{syst}) x 10^{-6} at redshift z=2.059$, which agrees well with a recently published result on the same system observed at the Keck telescope yielding Dmu/mu = (5.6 \pm 5.5_{stat} \pm 2.9_{syst}) x 10^{-6}. Both analyses used the same robust absorption line fitting procedures with detailed consideration of systematic errors.Comment: Accepte

Negative Attribution Bias and Anger After Traumatic Brain Injury

Objectives: Negative attributions pertain to judgments of intent, hostility, and blame regarding others' behaviors. This study compared negative attributions made by people with and without traumatic brain injury (TBI) and examined the degree to which these negative attributions predicted angry ratings in response to situations. Setting: Outpatient rehabilitation hospital. Participants: Forty-six adults with moderate to severe TBI and 49 healthy controls. Design: Cross-sectional study using a quasi-experimental research design. Main Measures: In response to hypothetical scenarios, participants rated how irritated and angry they would be, and how intentional, hostile, and blameworthy they perceived characters' behaviors. There were 3 scenario types differentiated by the portrayal of characters' actions: benign, ambiguous, or hostile. All scenarios theoretically resulted in unpleasant outcomes for participants. Results: Participants with TBI had significantly higher ratings for feeling “irritated” and “angry” and attributions of “intent,” “hostility,” and “blame” compared with healthy controls for all scenario types. Negative attribution ratings accounted for 72.4% and 65.3% of the anger rating variance for participants with and without TBI, respectively. Conclusion: People with TBI may have negative attribution bias, in which they disproportionately judge the intent, hostility, and blameworthiness of others' behaviors. These attributions contributed to their ratings of feeling angry. This suggests that participants with TBI who have anger problems should be evaluated for this bias, and anger treatments should possibly aim to alter negative attributions. However, before implementing clinical practice changes, there is a need for replication with larger samples, and further investigation of the characteristics associated with negative attribution bias

Reductions in Alexithymia and Emotion Dysregulation After Training Emotional Self-Awareness Following Traumatic Brain Injury: A Phase I Trial

OBJECTIVES: To examine the acceptability and initial efficacy of an emotional self-awareness treatment at reducing alexithymia and emotion dysregulation in participants with traumatic brain injury (TBI). SETTING: An outpatient rehabilitation hospital. PARTICIPANTS: Seventeen adults with moderate to severe TBI and alexithymia. Time postinjury ranged 1 to 33 years. DESIGN: Within subject design, with 3 assessment times: baseline, posttest, and 2-month follow-up. INTERVENTION: Eight lessons incorporated psychoeducational information and skill-building exercises teaching emotional vocabulary, labeling, and differentiating self-emotions; interoceptive awareness; and distinguishing emotions from thoughts, actions, and sensations. MEASURES: Toronto Alexithymia Scale-20 (TAS-20); Levels of Emotional Awareness Scale (LEAS); Trait Anxiety Inventory (TAI); Patient Health Questionnaire-9 (PHQ-9); State-Trait Anger Expression Inventory (STAXI); Difficulty With Emotion Regulation Scale (DERS); and Positive and Negative Affect Scale (PANAS). RESULTS: Thirteen participants completed the treatment. Repeated-measures analysis of variance revealed changes on the TAS-20 (P = .003), LEAS (P < .001), TAI (P = .014), STAXI (P = .015), DERS (P = .020), and positive affect (P < .005). Paired t tests indicated significant baseline to posttest improvements on these measures. Gains were maintained at follow-up for the TAS, LEAS, and positive affect. Treatment satisfaction was high. CONCLUSION: This is the first study published on treating alexithymia post-TBI. Positive changes were identified for emotional self-awareness and emotion regulation; some changes were maintained several months posttreatment. Findings justify advancing to the next investigational phase for this novel intervention