On Geometric Phase from Pure Projections

The geometric phase is usually treated as a quantity modulo 2\pi, a convention carried over from early work on the subject. The results of a series of optical interference experiments involving polarization of light, done by the present author (reviewed in R.Bhandari, Phys. Rep. 281 (1997) p.1) question the usefulness of such a definition of the geometric phase in that it throws away useful and measurable information about the system, for example strengths of singularities giving rise to the geometric phase. Such singularities have been directly demonstrated by phase-shift measurement in interference experiments. In this paper, two recent polarization experiments (Hariharan et.al., J.Mod.Opt. 44 (1997)p.707 and Berry and Klein, J.Mod.Opt. 43 (1996)p.165) are analysed and compared with previous experiments and potentially detectible singularities in these experiments pointed out.Comment: Latex, 15 pages, 6 figures; ([email protected]

Observable Dirac-type singularities in Berry's phase and the monopole

The physical reality and observability of 2n\pi Berry phases, as opposed to the usually considered modulo 2\pi topological phases is demonstrated with the help of computer simulation of a model adiabatic evolution whose parameters are varied along a closed loop in the parameter space. Using the analogy of Berry's phase with the Dirac monopole, it is concluded that an interferometer loop taken around a magnetic monopole of strength n/2 yields an observable 2n\pi phase shift, where n is an integer. An experiment to observe the effect is proposed.Comment: 12 pages Latex, 3 postscript figures; submitted to Physical Review Letters 15 September 2000; revised 19 November 200

Loop Tiling in the Presence of Exceptions

Exceptions in OO languages provide a convenient mechanism to deal with anomalous situations. However, many of the loop optimization techniques cannot be applied in the presence of conditional throw statements in the body of the loop, owing to possible cross iteration control dependences. Compilers either ignore such throw statements and apply traditional loop optimizations (semantic non-preserving), or conservatively avoid invoking any of these optimizations altogether (inefficient). We define a loop optimization to be xception-safe, if the optimization can be applied even on (possibly) exception throwing loops, in a semantics preserving manner. In this paper, we present a generalized scheme to do exception-safe loop optimizations and present a scheme of optimized exception-safe loop tiling (oESLT), as a specialization thereof. oESLT tiles the input loops, assuming that exceptions will never be thrown. To ensure the semantics preservation (in case an exception is thrown), oESLT generates code to rollback the updates done in the advanced iterations (iterations that the unoptimized code would not have executed, but executed speculatively by the oESLT generated code) and safely-execute the delayed iterations (ones that the unoptimized code would have executed, but not executed by the code generated by oESLT). For the rollback phase to work efficiently, oESLT identifies a minimal number of elements to backup and generates the necessary code. We implement oESLT, along with a naive scheme (nESLT, where we backup every element and do a full rollback and safe-execution in case an exception is thrown), in the Graphite framework of GCC 4.8. To help in this process, we define a new program region called ESCoPs (Extended Static Control Parts) that helps identify loops with multiple exit points and interface with the underlying polyhedral representation. We use the popular PolyBench suite to present a comparative evaluation of nESLT and oESLT against the unoptimized versions

Enhanced encryption technique for secure iot data transmission

Internet of things is the latest booming innovation in the current period, which lets the physical entity to process and intervene with the virtual entities. As all the entities are connected with each other, it generates load of data, which lacks proper security and privacy standards. Cryptography is one of the domains of Network Security, which is one such mechanism that helps the data transmission process to be secure enough over the wireless or wired channel and along with that, it provides authenticity, confidentiality, integrity of data and prevents repudiation. In this paper, we have proposed an alternate enhanced cryptographic solution combing the characteristic of symmetric, asymmetric encryption algorithms and Public Key Server. Here, the key pairs of end points (User’s Device and IoT device) are generated using Elliptic Curve Cryptography and the respective public keys are registered in Public Key Server along with their unique MAC address. Thereafter, both the ends will agree on one common private secret key, which will be the base for further cryptographic process using AES algorithm. This model can be called as multi-phase protection mechanism. It will make the process of data transmission secure enough that no intermediate can tamper the data

Description of a new species cephaline gregarine Stenophora bristili (Apicomplexa, Sporozoea) from Millipede (Chondromorpha severini) in Aurangabad district (M.S), India

The study of the endoparasitic cephaline gregarine in the gut content of millipede (Chondromorpha severini) was found to be infested with a new species (Stenophora bristili) of genus Stenophora (Labee, 1899). It differs from all the earlier reported species. The shape of the body of cephalont small elongated, slightly curved and rounded posterior end. Potomerite consists of fine bundle of bristles. The Sporont is elongated curved, slightly tapering and rounded posterior end, having brush like broader in between protomerite and deutomerite, Nucleus isspherical with ecentric karyosome. The different developmental stages including cephalont, sporont, gametocyst and sporocyst have been observed

The physiological effects of Transcranial Electrical Stimulation do not apply to parameters commonly used in studies of Cognitive Neuromodulation

Transcranial direct current stimulation (tDCS) and transcranial random noise stimulation (tRNS) have been claimed to produce many remarkable enhancements in perception, cognition, learning and numerous clinical conditions. The physiological basis of the claims for tDCS rests on the finding that 1 mA of unilateral anodal stimulation increases cortical excitation and 1 mA of cathodal produces inhibition. Here we show that these classic excitatory and inhibitory effects do not hold for the bilateral stimulation or 2 mA intensity conditions favoured in cognitive enhancement experiments. This is important because many, including some of the most salient claims are based on experiments using 2 mA bilateral stimulation. The claims for tRNS are also based on unilateral stimulation. Here we show that, again the classic excitatory effects of unilateral tRNS do not extend to the bilateral stimulation preferred in enhancement experiments. Further, we show that the effects of unilateral tRNS do not hold when one merely doubles the stimulation duration. We are forced to two conclusions: (i) that even if all the data on TES enhancements are true, the physiological explanations on which the claims are based are at best not established but at worst false, and (ii) that we cannot explain, scientifically at least, how so many experiments can have obtained data consistent with physiological effects that may not exist

Topological properties of Berry's phase

By using a second quantized formulation of level crossing, which does not assume adiabatic approximation, a convenient formula for geometric terms including off-diagonal terms is derived. The analysis of geometric phases is reduced to a simple diagonalization of the Hamiltonian in the present formulation. If one diagonalizes the geometric terms in the infinitesimal neighborhood of level crossing, the geometric phases become trivial for any finite time interval $T$. The topological interpretation of Berry's phase such as the topological proof of phase-change rule thus fails in the practical Born-Oppenheimer approximation, where a large but finite ratio of two time scales is involved.Comment: 9 pages. A new reference was added, and the abstract and the presentation in the body of the paper have been expanded and made more precis

Report of new species of ciliate from the genus Metaradiophrya (Heidenrich, 1935) in Pheretima elongata from Aurangabad district (M.S.) India.

New species of ciliates belong to genus Metaradiophrya was recorded from intestine of Pheretima elongata, collected from Aurangabad district (M.S.). In the present study, morphological characteristics of this ciliate and its similarities and differences were discussed compared with other species of this genus