Quantitative analysis of pedestrian counterflow in a cellular automaton model

Pedestrian dynamics exhibits various collective phenomena. Here we study bidirectional pedestrian flow in a floor field cellular automaton model. Under certain conditions, lane formation is observed. Although it has often been studied qualitatively, e.g., as a test for the realism of a model, there are almost no quantitative results, neither empirically nor theoretically. As basis for a quantitative analysis we introduce an order parameter which is adopted from the analysis of colloidal suspensions. This allows to determine a phase diagram for the system where four different states (free flow, disorder, lanes, gridlock) can be distinguished. Although the number of lanes formed is fluctuating, lanes are characterized by a typical density. It is found that the basic floor field model overestimates the tendency towards a gridlock compared to experimental bounds. Therefore an anticipation mechanism is introduced which reduces the jamming probability.Comment: 11 pages, 12 figures, accepted for publication in Phys. Rev.

Constraining the Inflationary Equation of State

We explore possible constraints on the inflationary equation state: p=w\rho. While w must be close to -1 for those modes that contribute to the observed power spectrum, for those modes currently out of experimental reach, the constraints on w are much weaker, with only w<-1/3 as an a priori requirement. We find, however, that limits on the reheat temperature and the inflationary energy scale constrain w further, though there is still ample parameter space for a vastly different (accelerating) equation of state between the end of quasi-de Sitter inflation and the beginning of the radiation-dominated era. In the event that such an epoch of acceleration could be observed, we review the consequences for the primordial power spectrum.Comment: 12 pages, 2 figur

Sub-Riemannian Geometry and Time Optimal Control of Three Spin Systems: Quantum Gates and Coherence Transfer

Many coherence transfer experiments in Nuclear Magnetic Resonance Spectroscopy, involving network of coupled spins, use temporary spin-decoupling to produce desired effective Hamiltonians. In this paper, we show that significant time can be saved in producing an effective Hamiltonian, if spin-decoupling is avoided. We provide time optimal pulse sequences for producing an important class of effective Hamiltonians in three spin networks. These effective Hamiltonians are useful for coherence transfer experiments and implementation of quantum logic gates in NMR quantum computing. It is demonstrated that computing these time optimal pulse sequences can be reduced to geometric problems that involve computing sub-Riemannian geodesics on Homogeneous spaces

Features of deSitter Vacua in M-Theory

We compute the masses of all moduli in the unstable deSitter vacua arising in the toy model of cosmological M-theory flux compactifications on the G2 holonomy manifolds of [1]. The slow-roll parameters in the tachyonic directions are shown to be too large to be useful for conventional models of inflation. However, it appears that we can find fast roll regimes which could, under certain conditions, account for the current dark energy driven accelerated expansion of the universe.Comment: 14 pages, 1 figur

Optimal Control of Quantum Dissipative Dynamics: Analytic solution for cooling the three level Λ\Lambda system

We study the problem of optimal control of dissipative quantum dynamics. Although under most circumstances dissipation leads to an increase in entropy (or a decrease in purity) of the system, there is an important class of problems for which dissipation with external control can decrease the entropy (or increase the purity) of the system. An important example is laser cooling. In such systems, there is an interplay of the Hamiltonian part of the dynamics, which is controllable and the dissipative part of the dynamics, which is uncontrollable. The strategy is to control the Hamiltonian portion of the evolution in such a way that the dissipation causes the purity of the system to increase rather than decrease. The goal of this paper is to find the strategy that leads to maximal purity at the final time. Under the assumption that Hamiltonian control is complete and arbitrarily fast, we provide a general framework by which to calculate optimal cooling strategies. These assumptions lead to a great simplification, in which the control problem can be reformulated in terms of the spectrum of eigenvalues of $\rho$, rather than $\rho$ itself. By combining this formulation with the Hamilton-Jacobi-Bellman theorem we are able to obtain an equation for the globaly optimal cooling strategy in terms of the spectrum of the density matrix. For the three-level $\Lambda$ system, we provide a complete analytic solution for the optimal cooling strategy. For this system it is found that the optimal strategy does not exploit system coherences and is a 'greedy' strategy, in which the purity is increased maximally at each instant.Comment: 9 pages, 3 fig

जलवायु परिवर्तन से निपटने के लिए परिवार - ClimEd Series - (Households in combating climate change- ClimEd Series:5B)

Earth’s climate is always changing. In the past, it has gone through warmer and cooler periods which last for thousands of years. The changing climate can be due to natural and anthropogenic activities. Natural causes include changes in earth's orbit, sunspot activity; ocean changes and volcanic eruptions. Recently earth’s climate has been warming alarmingly which is mainly due to human activities like burning of coal, oil and natural gas which can lead to severe impacts across the globe

Evaluation of Onion Genotypes for Growth and Bulb Yield in Mid Hill of Nepal

Experiments were conducted at Horticulture Research Division (HRD), Khumaltar, Lalitpur; and Horticulture Research Station (HRS), Kimugaun, Dailekh in 2017/18 to evaluate the high yielding open pollinated genotypes of onion in mid hills of both locations. &nbsp;Five onion genotypes namely AVON-1016, AVON-1027, AVON-1028, AVON-1052, AVON-1074 and AVON-1103 received from Asian Vegetable Research and Development Centre were evaluated with local check variety and recommended variety Red Creole in both locations in randomized complete block design with 4 replications. The main objective of the experiment is to findout the high yielding open pollinated onion genotypes for mid hill condition.The pooled analysis of data over locations showed significant differences on plant height, neck diameter, bulb diameter, weight of bulbs and adjusted bulb yield per hectare. &nbsp;&nbsp;Introduced genotypes AVON 1027 (38.83 t/ha), AVON 1052 (31.97 t/ha) and AVON 1028 (31.48 t/ha) produced significantly higher yield than recommended and commercially cultivated check variety Red Creole (27.04 t/ha). Therefore the genotype AVON 1027 can be selected as the best genotype for growing in mid hills of Nepa