Bootstrap methods for the empirical study of decision-making and information flows in social systems

Abstract: We characterize the statistical bootstrap for the estimation of information theoretic quantities from data, with particular reference to its use in the study of large-scale social phenomena. Our methods allow one to preserve, approximately, the underlying axiomatic relationships of information theory—in particular, consistency under arbitrary coarse-graining—that motivate use of these quantities in the first place, while providing reliability comparable to the state of the art for Bayesian estimators. We show how information-theoretic quantities allow for rigorous empirical study of the decision-making capacities of rational agents, and the time-asymmetric flows of information in distributed systems. We provide illustrative examples by reference to ongoing collaborative work on the semantic structure of the British Criminal Court system and the conflict dynamics of the contemporary Afghanistan insurgency

Evaluation of Current Heparin Weight Based Protocol in Obese Patients

Purpose: To evaluate the difference in achieving goal activated partial thromboplastin time (aPTT) within 24 hours utilizing the institutional heparin weight based protocol between obese and non-obese patients. Methods: Retrospective, non-randomized, open label chart review in a community based hospital. Patients age 18 years or older receiving heparin therapy for greater than or equal to 24 hours identified. Patients were excluded if the protocol was utilized for acute coronary syndrome or interrupted within the initial 24 hours of therapy. Patients were also excluded if any deviations from the protocol were identified. The primary endpoint evaluated the difference in achieving goal aPTT within 24 hours between obese and non-obese patients. The secondary endpoint evaluated the difference in achieving goal aPTT within 24-48 hours and safety outcomes such as bleeds. Results: Of the 253 patients identified, 167 patients were included and 86 patients were excluded. Seventy-two (71.3%) of the nonobese and 48 (72.7%) of obese patients achieved goal aPTT within 24 hours (odd ratio [OR]: 0.98, 95 % confidence interval (CI): 0.6 to 1.58). Sixteen (15.8%) of nonobese and 13 (19.7%) of the obese patients achieved goal aPTT within 24 to 48 hours (OR: 0.77, 95 % CI: 0.3 to 1.95). Two (1.9 %) of the nonobese and 3 (4.5 %) of the obese patients had a documented major bleed (OR: 0.42 and 95 % CI: 0.69 to 2.61). Conclusion: Overall, there was no difference in achieving goal aPTT between nonobese and obese patients while utilizing our facility’s weight based heparin dosing. No major bleeding was documented that warranted discontinuation of therapy, and bleeding incidences between both groups were similar

Joint Relay Selection and Power Allocation in Large-Scale MIMO Systems with Untrusted Relays and Passive Eavesdroppers

In this paper, a joint relay selection and power allocation (JRP) scheme is proposed to enhance the physical layer security of a cooperative network, where a multiple antennas source communicates with a single-antenna destination in presence of untrusted relays and passive eavesdroppers (Eves). The objective is to protect the data confidentially while concurrently relying on the untrusted relays as potential Eves to improve both the security and reliability of the network. To realize this objective, we consider cooperative jamming performed by the destination while JRP scheme is implemented. With the aim of maximizing the instantaneous secrecy rate, we derive a new closed-form solution for the optimal power allocation and propose a simple relay selection criterion under two scenarios of non-colluding Eves (NCE) and colluding Eves (CE). For the proposed scheme, a new closed-form expression is derived for the ergodic secrecy rate (ESR) and the secrecy outage probability as security metrics, and a new closed-form expression is presented for the average symbol error rate (SER) as a reliability measure over Rayleigh fading channels. We further explicitly characterize the high signal-to-noise ratio slope and power offset of the ESR to highlight the impacts of system parameters on the ESR. In addition, we examine the diversity order of the proposed scheme to reveal the achievable secrecy performance advantage. Finally, the secrecy and reliability diversity-multiplexing tradeoff of the optimized network are provided. Numerical results highlight that the ESR performance of the proposed JRP scheme for NCE and CE cases is increased with respect to the number of untrustworthy relays.Comment: 18 pages, 10 figures, IEEE Transactions on Information Forensics and Security (In press

A model for the orientational ordering of the plant microtubule cortical array

The plant microtubule cortical array is a striking feature of all growing plant cells. It consists of a more or less homogeneously distributed array of highly aligned microtubules connected to the inner side of the plasma membrane and oriented transversely to the cell growth axis. Here we formulate a continuum model to describe the origin of orientational order in such confined arrays of dynamical microtubules. The model is based on recent experimental observations that show that a growing cortical microtubule can interact through angle dependent collisions with pre-existing microtubules that can lead either to co-alignment of the growth, retraction through catastrophe induction or crossing over the encountered microtubule. We identify a single control parameter, which is fully determined by the nucleation rate and intrinsic dynamics of individual microtubules. We solve the model analytically in the stationary isotropic phase, discuss the limits of stability of this isotropic phase, and explicitly solve for the ordered stationary states in a simplified version of the model.Comment: 15 pages, 5 figure

Survival of the aligned: ordering of the plant cortical microtubule array

The cortical array is a structure consisting of highly aligned microtubules which plays a crucial role in the characteristic uniaxial expansion of all growing plant cells. Recent experiments have shown polymerization-driven collisions between the membrane-bound cortical microtubules, suggesting a possible mechanism for their alignment. We present both a coarse-grained theoretical model and stochastic particle-based simulations of this mechanism, and compare the results from these complementary approaches. Our results indicate that collisions that induce depolymerization are sufficient to generate the alignment of microtubules in the cortical array.Comment: 4+ pages, 3 figures v2: significantly revised the exposition of the analytical model and expanded the discussion on our choice for the collision outcome probabilities; clarified the scope of the conclusions; numerous smaller changes throughou

Sun protection: North and South – a comparison of attitudes and behaviours of young adults in the UK and NZ: implications for UK interventions

Skin cancer rates have steadily risen in the UK, doubling approximately every twenty years. There has been no significant mass media expenditure within the UK on improving public awareness of the link between sun exposure and skin cancer risk. In countries such as New Zealand, where extensive mass media and population segment-specific interventions have run for several years, melanoma rates show a decline, suggesting that mass media interventions should be considered within the UK and other European countries to help reduce skin cancer rates. Before considering the possibility of using similar mass media-based communication strategies to those used in New Zealand, an understanding of the attitudes and beliefs that underpin existing sun protective behaviours in both countries would be beneficial. We focus on adolescents as a target as this segment has particularly poor sun protective behaviours and appears resistant to health-based interventions .We therefore compare the attitudes, beliefs and actual reported behaviours of young adults in the UK and New Zealand identifying less than optimal sun protective behaviours in both countries. The findings suggest that the UK or other countries - should not adopt similar communication strategies to New Zealand without addressing underlying normative factors underpinning behaviours