Proton albedo spectrum observation in low latitude region at Hyderabad, India

The flux and the energy spectrum of low energy (30-100 MeV) proton albedos, have been observed for the first time in a low latitude region, over Hyderabad, India. The preliminary results, based on the quick look data acquisition and display system are presented. A charged particle telescope, capable of distinguishing singly charged particles such as electrons, muons, protons in low energy region, records the data of both upward as well as downward moving particles. Thus spectra of splash and re-entrant albedo protons have been recorded simultaneously in a high altitude Balloon flight carried out on 8th December, 1985, over Hyderabad, India. Balloon floated at an latitude of approx. 37 km (4 mb)

Testing surface area with arbitrary accuracy

Recently, Kothari et al.\ gave an algorithm for testing the surface area of an arbitrary set $A \subset [0, 1]^n$. Specifically, they gave a randomized algorithm such that if $A$'s surface area is less than $S$ then the algorithm will accept with high probability, and if the algorithm accepts with high probability then there is some perturbation of $A$ with surface area at most $\kappa_n S$. Here, $\kappa_n$ is a dimension-dependent constant which is strictly larger than 1 if $n \ge 2$, and grows to $4/\pi$ as $n \to \infty$. We give an improved analysis of Kothari et al.'s algorithm. In doing so, we replace the constant $\kappa_n$ with $1 + \eta$ for $\eta > 0$ arbitrary. We also extend the algorithm to more general measures on Riemannian manifolds.Comment: 5 page

Defence Science and its organization

The most fertile field for operational research is that concerned with weapon economics, that is the evaluation of effectiveness of a weapon A compared with say another weapon B. This problem of evaluation of weapon efficiencies, or weapon economics for brevity, arises at all levels. Advantages to change from say Rifle A to Rifle B

Science and defence

Science is a comparatively recent thing in man's history, and newer still is its cultivation on an organized scale and its large scale application in peace and war. As everyone now knows, science is an immensely powerful thing. It has profoundly altered man's material environment and it has even altered his pattern of thinking and his sense of values. It has deeply affected the way we look at the world and its problems. It has given new meaning to old problems-including the problem of living and life itself-and it has raised a host of new ones. In all civilized countries, science (-but not always, and not necessarily, scientists-) enjoys tremendous prestige, and people have great hope and faith in its power of doing good, and there is also the fear that this power may not wisely used. And, all this has taken place in the amazingly short period of about three centuries

A bi-directional charged particle telescope to observe flux, energy spectrum and angular distribution of relativistic and non-relativistic particles

A Charged Particle Telescope (CPT) was designed, fabricated and calibrated to make the following observations: (1) discrimination between various singly charged particles, e.g., electrons, muons and protons, in about 5 to 100 MeV energy range; (2) measurement of the flux and the energy of the charged particles incident to the telescope from two opposite directions and stopping in the telescope, thus obtaining flux and energy spectrum of downward and upward moving charged particles; and (3) measurement of the broad angular distribution of selected particles as a function of azimuthal angle. This telescope can be used to study low energy electron, muon and proton energy spectra. The experiment was flown in a high altitude balloon from Hyderabad, India, in December 1984. This same equipment is also useful in ground level electron, muon spectrum study

Exponential improvement in precision for simulating sparse Hamiltonians

We provide a quantum algorithm for simulating the dynamics of sparse Hamiltonians with complexity sublogarithmic in the inverse error, an exponential improvement over previous methods. Specifically, we show that a $d$-sparse Hamiltonian $H$ acting on $n$ qubits can be simulated for time $t$ with precision $\epsilon$ using $O\big(\tau \frac{\log(\tau/\epsilon)}{\log\log(\tau/\epsilon)}\big)$ queries and $O\big(\tau \frac{\log^2(\tau/\epsilon)}{\log\log(\tau/\epsilon)}n\big)$ additional 2-qubit gates, where $\tau = d^2 \|{H}\|_{\max} t$. Unlike previous approaches based on product formulas, the query complexity is independent of the number of qubits acted on, and for time-varying Hamiltonians, the gate complexity is logarithmic in the norm of the derivative of the Hamiltonian. Our algorithm is based on a significantly improved simulation of the continuous- and fractional-query models using discrete quantum queries, showing that the former models are not much more powerful than the discrete model even for very small error. We also simplify the analysis of this conversion, avoiding the need for a complex fault correction procedure. Our simplification relies on a new form of "oblivious amplitude amplification" that can be applied even though the reflection about the input state is unavailable. Finally, we prove new lower bounds showing that our algorithms are optimal as a function of the error.Comment: v1: 27 pages; Subsumes and improves upon results in arXiv:1308.5424. v2: 28 pages, minor change

Simulating Hamiltonian dynamics with a truncated Taylor series

We describe a simple, efficient method for simulating Hamiltonian dynamics on a quantum computer by approximating the truncated Taylor series of the evolution operator. Our method can simulate the time evolution of a wide variety of physical systems. As in another recent algorithm, the cost of our method depends only logarithmically on the inverse of the desired precision, which is optimal. However, we simplify the algorithm and its analysis by using a method for implementing linear combinations of unitary operations to directly apply the truncated Taylor series.Comment: 5 page