A cluster theory for a Janus fluid

Recent Monte Carlo simulations on the Kern and Frenkel model of a Janus fluid have revealed that in the vapour phase there is the formation of preferred clusters made up of a well-defined number of particles: the micelles and the vesicles. A cluster theory is developed to approximate the exact clustering properties stemming from the simulations. It is shown that the theory is able to reproduce the micellisation phenomenon.Comment: 27 pages, 8 figures, 6 table

CITRONELLA AGROFORESTRY IN GAYO LUES REGENCY OF INDONESIA

An agroforestry practice system has been applied by Gayo Lues community in managing their agricultural land. The most dominant tree species treated by farmers among the citronella plants is pine. The population in this study was 2,403 farmers. From the total population, samples were taken by using Slovin formula so that the sample became 96 farmers. The agroforestry system in Gayo Lues Regency uses a blend of pine trees (woody plants) with citronella plants (non-woody plants). The optimal area of citronella agroforestry for farmers is 1.3 ha. They have fulfilled the needs of a decent living in this area

Exact Analytic Solution for the Rotation of a Rigid Body having Spherical Ellipsoid of Inertia and Subjected to a Constant Torque

The exact analytic solution is introduced for the rotational motion of a rigid body having three equal principal moments of inertia and subjected to an external torque vector which is constant for an observer fixed with the body, and to arbitrary initial angular velocity. In the paper a parametrization of the rotation by three complex numbers is used. In particular, the rows of the rotation matrix are seen as elements of the unit sphere and projected, by stereographic projection, onto points on the complex plane. In this representation, the kinematic differential equation reduces to an equation of Riccati type, which is solved through appropriate choices of substitutions, thereby yielding an analytic solution in terms of confluent hypergeometric functions. The rotation matrix is recovered from the three complex rotation variables by inverse stereographic map. The results of a numerical experiment confirming the exactness of the analytic solution are reported. The newly found analytic solution is valid for any motion time length and rotation amplitude. The present paper adds a further element to the small set of special cases for which an exact solution of the rotational motion of a rigid body exists.Comment: "Errata Corridge Postprint" In particular: typos present in Eq. 28 of the Journal version are HERE correcte

Kolmogorov-Sinai entropy from recurrence times

Observing how long a dynamical system takes to return to some state is one of the most simple ways to model and quantify its dynamics from data series. This work proposes two formulas to estimate the KS entropy and a lower bound of it, a sort of Shannon's entropy per unit of time, from the recurrence times of chaotic systems. One formula provides the KS entropy and is more theoretically oriented since one has to measure also the low probable very long returns. The other provides a lower bound for the KS entropy and is more experimentally oriented since one has to measure only the high probable short returns. These formulas are a consequence of the fact that the series of returns do contain the same information of the trajectory that generated it. That suggests that recurrence times might be valuable when making models of complex systems

Human Factors Aspects of the Transfer of Control from the Automated Highway System to the Driver

DTFH61-92-C-00100The first two experiments in a series exploring human factors issues related to the Automated Highway System (AHS) used a generic AHS configuration--the left lane reserved for automated vehicles, the center and right lanes containing unautomated vehicles, no transition lane, and no barriers between the automated and unautomated lanes--that was simulated in the Iowa Driving Simulator (IDS). The IDS has a moving base hexapod platform containing a mid-sized sedan. Imagery was projected onto a 3.35-rad (180 deg) screen in front of the driver, and onto a 1.13-rad (60 deg) screen to the rear. Thirty-six drivers between the ages of 25 and 34 years participated in the first experiment; 24 drivers who were age 65 or older took part in the second. Both experiments explored the transfer of control from the AHS to the driver when the driver's task was to leave the automated lane. The driver, who was traveling under automated control in a string of vehicles in the automated lane, had to take control, drive from the automated lane into the center lane, then leave the freeway. Results were as follows: (1) The mean time to respond to an "Exit" advisory decreased from 13.41 s to 10.16 s as the design velocity increased from 104.7 km/h (65 mi/h) to 153.0 km/h (95 mi/h). (2) After the transfer of control, the driver remained in the automated lane, decelerating until the velocity was slow enough to allow a safe transition into the slower traffic in the unautomated lanes. It took longer to decelerate (13.19 s vs. 10.26 s) and the exit velocity dropped [105.30 km/h (65.40 mi/h) vs. 99.54 km/h (61.83 mi/h)] as the unautomated traffic density decreased from 12.42 v/km/ln (20 v/mi/ln) to 6.21 v/km/ln (10 v/mi/ln). It also took longer to decelerate (15.23 s vs. 8.62 s) and the extent of the deceleration decreased [42.7 km/h (26.49 mi/h) vs. 13.18 km/h (8.16 mi/h)] as the design velocity decreased from 153.0 km/h (95 mi/h) to 104.7 km/h (65 mi/h). (3) Once in the unautomated lanes, the younger drivers were in the center lane 70% longer than the older drivers. (4) The vehicle immediately behind the driver's vehicle in the automated lane was delayed after control was transferred--the delay increased from 1.36 s to 6.70 s as the design velocity increased from 104.7 km/h (65 mi/h) to 153 km/h (95 mi/h). (5) Allowing for the delay times obtained in these experiments, it was determined that the potential capacity of an automated lane should increase from 634.6 v/h to 2087.8 v/h as the design velocity decreases from 153.0 km/h (95 mi/h) to 104.7 km/h (65 mi/h). (6) Collisions and incursions occurred at unacceptably high rates. (7) The responses to the questionnaire suggest that the drivers were receptive to the AHS concept

First Observation of barB0 to D*0 pi+pi+pi-pi- Decays

We report on the observation of B0bar -> D*0 pi+ pi+ pi- pi- decays. The branching ratio is (0.30 +/- 0.07 +/- 0.06)%. Interest in this particular mode was sparked by Ligeti, Luke and Wise who propose it as a way to check the validity of factorization tests in B0bar -> D*+ pi+ pi- pi- pi0 decays.Comment: 11 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, Version to appear in Phys. Rev.

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter