Convergence in distribution of quotients of order statistics

AbstractLet X1, X2,… be i.i.d. random variables with continuous distribution function F < 1. It is known that if 1 - F(x) varies regularly of order - p, the successive quotients of the order statistics in decreasing order of X1,…,Xn are asymptotically independent, as n→∞, with distribution functions xkp, k = 1, 2, …. A strong converse is proved, viz. convergence in distribution of this type of one of the quotients implies regular varation of 1 - F(x)

Motivation in words: promotion- and prevention-oriented leader communication in times of crisis

Research demonstrates that situational uncertainty or crisis strongly influences the endorsement of the more charismatic or decisive leadership styles and that inspirational communication is at the heart of these styles. However, there is currently little understanding of what leaders should convey through their communication to be endorsed in crisis. Based on regulatory focus theory, we argue that times of crisis make leaders who use more promotion-oriented communication more likely to be endorsed and leaders who use more prevention-oriented communication less likely to be endorsed. Results of Study 1, an archival study of U.S. presidents, show that presidents who use more promotion-oriented communication are more endorsed but only if economic growth is low or if inflation is high, while no effects of the use of prevention orientation of communication surfaces. Results of Study 2, a laboratory experiment, show that leaders who communicate a promotion orientation, as compared to a prevention orientation, motivate higher performance in participants in a crisis condition, but that there is no difference in a no-crisis (i.e. control) condition. Finally, results of Study 3, a scenario experiment, demonstrate that organizational leaders that communicate more promotion-oriented (as opposed to more prevention-oriented) have a higher chance of being endorsed but only in times of crisis and that this effect is mediated by followers’ motivation to realize the plans of the leader

Vertices and the CJT Effective Potential

The Cornwall-Jackiw-Tomboulis effective potential is modified to include a functional dependence on the fermion-gauge particle vertex, and applied to a quark confining model of chiral symmetry breaking.Comment: 10 pages (latex), PURD-TH-93-1

Motivation in words : promotion- and prevention-oriented leader communication in times of crisis.

Research demonstrates that situational uncertainty or crisis strongly influences the endorsement of the more charismatic or decisive leadership styles and that inspirational communication is at the heart of these styles. However, there is currently little understanding of what leaders should convey through their communication to be endorsed in crisis. Based on regulatory focus theory, we argue that times of crisis make leaders who use more promotion-oriented communication more likely to be endorsed and leaders who use more prevention-oriented communication less likely to be endorsed. Results of Study 1, an archival study of U.S. presidents, show that presidents who use more promotion-oriented communication are more endorsed but only if economic growth is low or if inflation is high, while no effects of the use of prevention orientation of communication surfaces. Results of Study 2, a laboratory experiment, show that leaders who communicate a promotion orientation, as compared to a prevention orientation, motivate higher performance in participants in a crisis condition, but that there is no difference in a no-crisis (i.e. control) condition. Finally, results of Study 3, a scenario experiment, demonstrate that organizational leaders that communicate more promotion-oriented (as opposed to more prevention-oriented) have a higher chance of being endorsed but only in times of crisis and that this effect is mediated by followers’ motivation to realize the plans of the leader

"Playstation eyetoy games" improve upper extremity-related motor functioning in subacute stroke:a randomized controlled clinical trial

Aim. To evaluate the effects of "Playstation EyeToy Games" on upper extremity motor recovery and upper extremity-related motor functioning of patients with subacute stroke. Methods. The authors designed a randomized, controlled, assessor-blinded, 4-week trial, with follow-up at 3 months. A total of 20 hemiparetic inpatients (mean age 61.1 years), all within 12 months post-stroke, received 30 minutes of treatment with "Playstation EyeToy Games" per day, consisting of flexion and extension of the paretic shoulder, elbow and wrist as well as abduction of the paretic shoulder or placebo therapy (watching the games for the same duration without physical involvement into the games) in addition to conventional program, 5 days a week, 2-5 hours/day for 4 weeks. Brunnstrom's staging and self-care subitems of the functional independence measure (FIM) were performed at 0 month (baseline), 4 weeks (post-treatment), and 3 months (follow-up) after the treatment. Results. The mean change score (95% confidence interval) of the FIM self-care score (5.5 [2.9-8.0] vs 1.8 [0.1-3.7], P=0.018) showed significantly more improvement in the EyeToy group compared to the control group. No significant differences were found between the groups for the Brunnstrom stages for hand and upper extremity. Conclusion. "Playstation EyeToy Games" combined with a conventional stroke rehabilitation program have a potential to enhance upper extremity-related motor functioning in subacute stroke patients.</div

Combined study of time-series bifurcation and power spectral behaviour of a thalamo-cortico-thalamic neural mass model

A combined power spectral and time-series bifurcation analysis of a neural mass model is presented. Such 'multi-modal' analytical techniques are being used in several researches to understand Electroencephalograph (EEG) anomalies in brain disorders [1][2], in contrast to 'power spectra-only' analytical studies that were more common during the early days of EEG analysis. In a recent work, a combined analysis of a simple thalamo-cortical neural mass model in context to EEG abnormality in Alzheimer's disease (AD) is presented [3]. The study shows that 'unimodal' analytical techniques such as power spectra-only studies without a simultaneous observation of the time-series model output may lead to anomalous conclusions and hypotheses. Towards this, in this work, a 'multi-modal' analytical technique is applied on a thalamocorticothalamic (tct) model, which was earlier studied using power-spectra analysis only [4]. The tct model is an enhanced version of that used in [3] and is based on biological data available in current literature. Furthermore, it aims to mimic thalalmocortical oscillations such as observed in the EEG of both healthy and diseased brain. Here, the power spectra of the tct model output is observed within the δ (1-3 Hz), θ (4-7 Hz), α (8-13 Hz), β (14-30 Hz) bands, along with a simultaneous analysis of the time series behaviour, the latter showing three behavioural modes: noisy point-attractor, spindle and limit-cycle. With all parameters at their basal values, the output time series is in a noisy point-attractor mode with maximum power within the alpha band (Figure 1). However the model shifts into a limit cycle oscillatory mode with a decrease in inhibitory connectivity parameters in the model (Figure 1); the corresponding power spectra show an increase in peak power within the θ and δ bands along with a simultaneous decrease in power within the α and β bands. The model behaviour is very much in agreement with in-vitro studies [5] which report an increased theta band power and a simultaneous decreased alpha band power during transition from wakefulness to sleep. Furthermore, the in-vitro time-series are qualitatively very similar to those obtained using the model. Thus, the model indicates a decreased inhibitory activity to be the neural correlate of the transitive state between wakefulness and sleep. On the other hand, increased mean firing activity of the extrinsic model inputs pushes the model, first into a spindling mode, and then into a limit cycle mode. In this state, the power within the delta band shows a significant increase compared to those within the other frequency bands. This behaviour is more similar to in-vivo studies of awake-to-sleep transition as reported in [5]

Test your surrogate data before you test for nonlinearity

The schemes for the generation of surrogate data in order to test the null hypothesis of linear stochastic process undergoing nonlinear static transform are investigated as to their consistency in representing the null hypothesis. In particular, we pinpoint some important caveats of the prominent algorithm of amplitude adjusted Fourier transform surrogates (AAFT) and compare it to the iterated AAFT (IAAFT), which is more consistent in representing the null hypothesis. It turns out that in many applications with real data the inferences of nonlinearity after marginal rejection of the null hypothesis were premature and have to be re-investigated taken into account the inaccuracies in the AAFT algorithm, mainly concerning the mismatching of the linear correlations. In order to deal with such inaccuracies we propose the use of linear together with nonlinear polynomials as discriminating statistics. The application of this setup to some well-known real data sets cautions against the use of the AAFT algorithm.Comment: 14 pages, 15 figures, submitted to Physical Review