Quantum Random Walks do not need a Coin Toss

Classical randomized algorithms use a coin toss instruction to explore different evolutionary branches of a problem. Quantum algorithms, on the other hand, can explore multiple evolutionary branches by mere superposition of states. Discrete quantum random walks, studied in the literature, have nonetheless used both superposition and a quantum coin toss instruction. This is not necessary, and a discrete quantum random walk without a quantum coin toss instruction is defined and analyzed here. Our construction eliminates quantum entanglement from the algorithm, and the results match those obtained with a quantum coin toss instruction.Comment: 6 pages, 4 figures, RevTeX (v2) Expanded to include relation to quantum walk with a coin. Connection with Dirac equation pointed out. Version to be published in Phys. Rev.

Effect of humidity on transonic flow

An experimental investigation of the effects of humidity-induced condensation on shock/boundary-layer interaction has been conducted in a transonic wind-tunnel test. The test geometry considered was a wall-mounted bump model inserted in the test section of the wind tunnel. The formation of a λ-shape condensation shock wave was shown from schlieren visualization and resulted in a forward movement of the shock wave, reduced shock wave strength, and reduced separation. Empirical correlations of the shock wave strength and humidity/dew point temperature were established. For humidity levels below 0.15 or a dew point temperature of 268 K, the effect of humidity was negligible. The unsteady pressure measurements showed that if a condensation shock wave formed and interacted with a main shock wave, the flow becomes unsteady with periodic flow oscillations occurring at 720 Hz

4,9-Dioxa-1,3(1,2)-dibenzena-2(4,5)-1,3-oxazolidinacyclononaphane

The oxazole ring in the title compound, C20H23NO3, adopts an envelope conformation while the 12-membered ring is in a chair conformation. The dihedral angle between the benzene rings is 37.8 (1)°. The crystal structure displays inter­molecular C—H⋯O hydrogen bonding

19-Ferrocenyl-18-oxa-8,16-diaza­penta­cyclo­[8.6.3.01,10.02,7.012,16]nona­deca-2(7),3,5-triene-9,17-dione

In the title compound, [Fe(C5H5)(C21H19N2O3)], both pyrrol­idine rings of the pyrrolizine substructure show an envelope conformation. In the ferrocenyl moiety, the unsubstituted cyclo­penta­dienyl ring is disordered over two orientations with site occupancies of 0.64 (2) and 0.36 (2). In the pyrrolizine ring, one C atom is disordered over two positions, with site occupancies of 0.71 (1) and 0.29 (1). Intra­molecular C—H⋯O inter­actions occur. The crystal packing is established through weak inter­molecular C—H⋯O and N—H⋯O inter­actions

SARAS 2: A Spectral Radiometer for probing Cosmic Dawn and the Epoch of Reionization through detection of the global 21 cm signal

The global 21 cm signal from Cosmic Dawn (CD) and the Epoch of Reionization (EoR), at redshifts $z \sim 6-30$, probes the nature of first sources of radiation as well as physics of the Inter-Galactic Medium (IGM). Given that the signal is predicted to be extremely weak, of wide fractional bandwidth, and lies in a frequency range that is dominated by Galactic and Extragalactic foregrounds as well as Radio Frequency Interference, detection of the signal is a daunting task. Critical to the experiment is the manner in which the sky signal is represented through the instrument. It is of utmost importance to design a system whose spectral bandpass and additive spurious can be well calibrated and any calibration residual does not mimic the signal. SARAS is an ongoing experiment that aims to detect the global 21 cm signal. Here we present the design philosophy of the SARAS 2 system and discuss its performance and limitations based on laboratory and field measurements. Laboratory tests with the antenna replaced with a variety of terminations, including a network model for the antenna impedance, show that the gain calibration and modeling of internal additives leave no residuals with Fourier amplitudes exceeding 2~mK, or residual Gaussians of 25 MHz width with amplitudes exceeding 2~mK. Thus, even accounting for reflection and radiation efficiency losses in the antenna, the SARAS~2 system is capable of detection of complex 21-cm profiles at the level predicted by currently favoured models for thermal baryon evolution.Comment: 44 pages, 17 figures; comments and suggestions are welcom

4′-Ferrocenyl-1′-methylacenapthylene-1-spiro-2′-pyrrolidine-3′-spiro-2′′-indane-2,1′′,3′′(1H)-trione

In the title compound, [Fe(C5H5)(C29H20NO3)], the acenaphthyl­ene ring system makes a dihedral angle of 83.77 (3)° with the indane-1,3-dione ring system. The central pyrrolidine ring exhibits a twist conformation. In the crystal, mol­ecules are linked by a weak inter­molecular C—H⋯O inter­action into a chain along the b axis. Two weak intra­molecular C—H⋯O inter­actions are also present

Methyl 9-p-tolyl-8a,9,9a,10,11,12,13,14a-octa­hydro-8H-benzo[f]chromeno[3,4-b]indolizine-8a-carboxyl­ate

In the title compound, C28H29NO3, the fused pyrrolidine and piperidine rings of the octa­hydro­indolizine unit exhibit envelope and chair conformations, respectively. The dihedral angle between the naphthalene ring system and the benzene ring is 40.37 (5)°. The crystal packing is stabilized by weak inter­molecular C—H⋯O inter­actions

Occurrence of black corals (order: Antipatharian) in Andaman and Nicobar Island, India

99-107A total of 15 species of antipatharians were accounted from the study sites. Maximum number of species was reported in Henry Lawrence Island and minimum in Paget Island, Rowe Island and North Reef Island. The present study yielded seven species (Cupressopathes abies, C. pumila, Tanacetipathes hirta, Antipathes dendrochristos, Cladopathes plumose, Trissopathes tetracrada, Dendrobathypathes boutillieri) and all are first report to India

New record of Melithaea retifera (Lamarck, 1816) from Andaman and Nicobar Island, India

1516-1520Alcyoniidae octocorals are represented by 405 species in India of which 154 are from Andaman and Nicobar Islands. Surveys conducted in Havelock Island, South Andaman and Shark Island, North Andaman revealed the occurrence of Melithaea retifera and is reported herein as a new distributional record to Andaman and Nicobar Islands. This species is characterised by the clubs of the coenenchyme of the node and internodes and looks like a flower-bud. The structural variations and length of sclerites in the samples are also reported in this manuscript

Diversity and distribution of shallow water octocorallia from Mahatma Gandhi Marine National Park, South Andaman, India

1567-1575Diversity and distribution of octocorals of Mahatma Gandhi Marine National Park (MGMNP), South Andaman were investigated from June, 2013 to May, 2016 using a Line Intercept Transect method with help of SCUBA diving. The study was carried out in 11 different islands named as Alexandra, Belle, Chester, Snob, Grub, Jolly Bouy, Boat, Red Skin Rutland, Tarmugli and Twins Islands. We undertook a systematic study on the diversity of octocorals. Thirty five species belonging to 29 genera were reported from MGMNP of which, the alcyonacea was a dominant group followed by gorgonacea, helioporacea and pennatulacea at all the study sites which is also substantiated by Principal Component analysis, and Ternary plot. Results on Bray-Curtis cluster analysis showed 35 % to 76 % similarity between the study sites in MGMNP