Eliciting a directed acyclic graph for a multivariate time series of vehicle counts in a traffic network

The problem of modelling multivariate time series of vehicle counts in traffic networks is considered. It is proposed to use a model called the linear multiregression dynamic model (LMDM). The LMDM is a multivariate Bayesian dynamic model which uses any conditional independence and causal structure across the time series to break down the complex multivariate model into simpler univariate dynamic linear models. The conditional independence and causal structure in the time series can be represented by a directed acyclic graph (DAG). The DAG not only gives a useful pictorial representation of the multivariate structure, but it is also used to build the LMDM. Therefore, eliciting a DAG which gives a realistic representation of the series is a crucial part of the modelling process. A DAG is elicited for the multivariate time series of hourly vehicle counts at the junction of three major roads in the UK. A flow diagram is introduced to give a pictorial representation of the possible vehicle routes through the network. It is shown how this flow diagram, together with a map of the network, can suggest a DAG for the time series suitable for use with an LMDM

Multibody Modeling and Simulation for the Mars Phoenix Lander Entry, Descent and Landing

A multi-body flight simulation for the Phoenix Mars Lander has been developed that includes high fidelity six degree-of-freedom rigid-body models for the parachute and lander system. The simulation provides attitude and rate history predictions of all bodies throughout the flight, as well as loads on each of the connecting lines. In so doing, a realistic behavior of the descending parachute/lander system dynamics can be simulated that allows assessment of the Phoenix descent performance and identification of potential sensitivities for landing. This simulation provides a complete end-to-end capability of modeling the entire entry, descent, and landing sequence for the mission. Time histories of the parachute and lander aerodynamic angles are presented. The response of the lander system to various wind models and wind shears is shown to be acceptable. Monte Carlo simulation results are also presented

Entry, Descent, and Landing Operations Analysis for the Mars Phoenix Lander

The Mars Phoenix lander was launched August 4, 2007 and remained in cruise for ten months before landing in the northern plains of Mars in May 2008. The one-month Entry, Descent, and Landing (EDL) operations phase prior to entry consisted of daily analyses, meetings, and decisions necessary to determine if trajectory correction maneuvers and environmental parameter updates to the spacecraft were required. An overview of the Phoenix EDL trajectory simulation and analysis that was performed during the EDL approach and operations phase is described in detail. The evolution of the Monte Carlo statistics and footprint ellipse during the final approach phase is also provided. The EDL operations effort accurately delivered the Phoenix lander to the desired landing region on May 25, 2008

Mars Phoenix Entry, Descent, and Landing Simulation Design and Modelling Analysis

The 2007 Mars Phoenix Lander was launched in August of 2007 on a ten month cruise to reach the northern plains of Mars in May 2008. Its mission continues NASA s pursuit to find evidence of water on Mars. Phoenix carries upon it a slew of science instruments to study soil and ice samples from the northern region of the planet, an area previously undiscovered by robotic landers. In order for these science instruments to be useful, it was necessary for Phoenix to perform a safe entry, descent, and landing (EDL) onto the surface of Mars. The EDL design was defined through simulation and analysis of the various phases of the descent. An overview of the simulation and various models developed to characterize the EDL performance is provided. Monte Carlo statistical analysis was performed to assess the performance and robustness of the Phoenix EDL system and are presented in this paper. Using these simulation and modelling tools throughout the design and into the operations phase, the Mars Phoenix EDL was a success on May 25, 2008

Toward a unified description of hadro- and photoproduction: S-wave pi- and eta-photoproduction amplitudes

The Chew-Mandelstam parameterization, which has been used extensively in the two-body hadronic sector, is generalized in this exploratory study to the electromagnetic sector by simultaneous fits to the pion- and eta-photoproduction S-wave multipole amplitudes for center-of-mass energies from the pion threshold through 1.61 GeV. We review the Chew-Mandelstam parameterization in detail to clarify the theoretical content of the SAID hadronic amplitude analysis and to place the proposed, generalized SAID electromagnetic amplitudes in the context of earlier employed parameterized forms. The parameterization is unitary at the two-body level, employing four hadronic channels and the gamma-N electromagnetic channel. We compare the resulting fit to the MAID parameterization and find qualitative agreement though, numerically, the solution is somewhat different. Applications of the extended parameterization to global fits of the photoproduction data and to global fits of the combined hadronic and photoproduction data are discussed.Comment: 9 pages, 9 figures; added figures and tex

FORMULATION AND IMMUNOSTIMULANT STABILITY POLYSACCHARIDE SYRUP OF FRACTION NONI (MORINDA CITRIFOLIA L.) FRUITS

Objective: The study aimed to formulate standardized polysaccharide fraction of Noni (SPFN) fruit into syrup preparations to fulfill the acceptability requirement of National Agency of Drugs and Food Control [Badan Pengawas Obat dan Makanan Republik of Indonesia (BPOM RI)] so that it can be used in the community as an immunostimulant. Methods: The optimization of the formula A and B were done using Simplex Lattice Design (SLD) method and its stability tested under extreme temperature change effect using thaw cycling method by evaluating the physical properties, microbial contamination and immunostimulant activity. MTT method was used to determine the immunostimulant activity of syrup against lymphocyte proliferation in vitro. Results: Based on the results of stability tests of formula A using pH (4.45), viscosity (81.03 mPas), taste (good taste), pouring power (2.31 s), amount of bacteria (68 colonies/ml), total yeast and mold (269 colonies/ml) parameters and fulfilled the acceptability requirement of BPOM RI. Formula A could maintain better stability than formula B. Formula A syrup used for immunostimulant activity testing that could increase lymphocyte proliferation at a concentration of 13.33 to 106.64 μg/μl and it’s stable under the influence of extreme temperature changes. Conclusion: Formula A could be used to produce SPFN syrup, which has stable physical properties and immunostimulant activity beside no microbial contamination that fulfill requirements of BPOM RI

The Phoenix Mars Landing: An Initial Look

This presentation was part of the session : Ongoing and Proposed EDL Technology DevelopmentSixth International Planetary Probe WorkshopNASA's Phoenix Mars Lander will make a landing on Mars on May 25th, 2008. Following on from the overview of the Phoenix entry, descent and landing (EDL) system given at IPPW5, an initial look at the Phoenix landing will be presented, highlighting the salient, high level events that occurred during EDL. Initial EDL flight reconstruction results will be presented, along with a retelling of the flight operations events that occurred on approach to Mars, and during the landing event itself. Note: Given the short time duration between the Phoenix landing and IPPW6, only a presentation will be prepared for the workshop.NAS

Researching the use of force: The background to the international project

This article provides the background to an international project on use of force by the police that was carried out in eight countries. Force is often considered to be the defining characteristic of policing and much research has been conducted on the determinants, prevalence and control of the use of force, particularly in the United States. However, little work has looked at police officers’ own views on the use of force, in particular the way in which they justify it. Using a hypothetical encounter developed for this project, researchers in each country conducted focus groups with police officers in which they were encouraged to talk about the use of force. The results show interesting similarities and differences across countries and demonstrate the value of using this kind of research focus and methodology

KN Scattering and the Nucleon Strangeness Radius

The leading non-zero electric moment of the nucleon strange-quark vector current is the mean square strangeness radius, $$. We evaluate the lightest OZI-allowed contribution to$$, arising from the kaon cloud, using dispersion relations. Drawing upon unitarity constraints as well as $K^{+}N$ scattering and $e^+e^-\to K\bar{K}$ cross section data, we find the structure of this contribution differs significantly from that suggested by a variety of QCD-inspired model calculations. In particular, we find evidence for a strong $\phi$-meson resonance which may enhance the scale of kaon cloud contribution to an observable level.Comment: 4 pages, RevTex, 1 PS figure, uses epsf.sty, revised to improve clarity, results unchange