Performance Analysis of Novel Randomly Shifted Certification Authority Authentication Protocol for MANETs

The provision of security in mobile ad hoc networks is of paramount importance due to their wireless nature. However, when conducting research into security protocols for ad hoc networks it is necessary to consider these in the context of the overall system. For example, communicational delay associated with the underlying MAC layer needs to be taken into account. Nodes in mobile ad hoc networks must strictly obey the rules of the underlying MAC when transmitting security-related messages while still maintaining a certain quality of service. In this paper a novel authentication protocol, RASCAAL, is described and its performance is analysed by investigating both the communicational-related effects of the underlying IEEE 802.11 MAC and the computational-related effects of the cryptographic algorithms employed. To the best of the authors' knowledge, RASCAAL is the first authentication protocol which proposes the concept of dynamically formed short-lived random clusters with no prior knowledge of the cluster head. The performance analysis demonstrates that the communication losses outweigh the computation losses with respect to energy and delay. MAC-related communicational effects account for 99% of the total delay and total energy consumption incurred by the RASCAAL protocol. The results also show that a saving in communicational energy of up to 12.5% can be achieved by changing the status of the wireless nodes during the course of operation. Copyright (C) 2009 G. A. Safdar and M. P. O'Neill (nee McLoone).

The Exotic Eclipsing Nucleus of the Ring Planetary Nebula SuWt 2

SuWt 2 is a planetary nebula (PN) consisting of a bright ionized thin ring seen nearly edge-on, with much fainter bipolar lobes extending perpendicularly to the ring. It has a bright (12th magnitude) central star, too cool to ionize the PN, which we discovered in the early 1990s to be an eclipsing binary. Although it was anticipated that there would also be an optically faint, hot, ionizing star in the system, a spectrum from the International Ultraviolet Explorer (IUE) did not reveal a UV source. We present extensive ground-based photometry and spectroscopy of the central binary collected over the ensuing two decades, resulting in the determination that the orbital period of the eclipsing pair is 4.9 days, and that it consists of two nearly identical A1 V stars, each of mass ~2.7 M sun. The physical parameters of the A stars, combined with evolutionary tracks, show that both are in the short-lived "blue-hook" evolutionary phase that occurs between the main sequence and the Hertzsprung gap, and that the age of the system is about 520 Myr. One puzzle is that the stars' rotational velocities are different from each other, and considerably slower than synchronous with the orbital period. It is possible that the center-of-mass velocity of the eclipsing pair is varying with time, suggesting that there is an unseen third orbiting body in the system. We propose a scenario in which the system began as a hierarchical triple, consisting of a ~2.9 M sun star orbiting the close pair of A stars. Upon reaching the asymptotic giant branch stage, the primary engulfed the pair into a common envelope, leading to a rapid contraction of the orbit and catastrophic ejection of the envelope into the orbital plane. In this picture, the exposed core of the initial primary is now a white dwarf of ~0.7 M sun, orbiting the eclipsing pair, which has already cooled below the detectability possible by IUE at our derived distance of 2.3 kpc and a reddening of E(B - V) = 0.40. The SuWt 2 system may be destined to perish as a Type Ia supernova.

Resonance Raman probing of the interaction between dipyridophenazine complexes of Ru(II) and DNA

Resonance Raman (RR) spectroscopy has been used to probe the interaction between dipyridophenazine (dppz) complexes of ruthenium(II), [Ru(L)(2)(dppz)](2+) (L = 1,10-phenanthroline (1) and 2,2-bipyridyl (2)), and calf-thymus DNA. Ground electronic state RR spectra at selected probe wavelengths reveal enhancement patterns which reflect perturbation of the dppz-centered electronic transitions in the UV-vis spectra in the presence of DNA. Comparison of the RR spectra recorded of the short-lived MLCT excited states of both complexes in aqueous solution with those of the longer-lived states of the complexes in the DNA environment reveals changes to excited state modes, suggesting perturbation of electronic transitions of the dppz ligand in the excited state as a result of intercalation. The most prominent feature, at 1526 cm(-1), appears in the spectra of both 1 and 2 and is a convenient marker band for intercalation. For 1, the excited state studies have been extended to the A and A enantiomers. The marker band appears at the same frequency for both but with different relative intensities. This is interpreted as reflecting the distinctive response of the enantiomers to the chiral environment of the DNA binding sites. The results, together with some analogous data for other potentially intercalating complexes, are considered in relation to the more general application of time-resolved RR spectroscopy for investigation of intercalative interactions of photoexcited metal complexes with DNA.

Time-resolved resonance Raman spectroscopy

Vibrational Raman spectroscopy is now widely recognized as a useful technique for chemical analysis. It has become increasingly popular for the characterization of stable species since the technology which underpins Raman measurements has matured. Time-resolved Raman spectroscopy has also become established as an excellent method for the characterization of transient chemical species but it is not so widely applied. However, the technical advances which have reduced the cost and increased the reliability of conventional: Raman systems can also be exploited in studies of transient species. In some cases it is just as straightforward to record the Raman-spectra of a short-lived transient species as it is to monitor a more stable sample. This raises the possibility of routinely adding time-domain Raman measurements to more conventional Raman techniques, increasing the selectivity of the analysis while retaining its ability to provide spectral information which is characteristic of the species under investigation.

CONTRIBUTION OF RESONANCE RAMAN EXCITATION SPECTROSCOPY FOR PROBING ELECTRONICALLY EXCITED-STATES - NATURE OF A PORPHYRIN-DNA EXCIPLEX

The resonance Raman spectra of a water-soluble metalloporphyrin Cu(TMpy-P4), complexed with a synthetic nucleic acid, poly(dA-dT), were measured by using excitation wavelengths located within the B (Soret) transition of the porphyrin (417-470 nm), while its excited state was synchronously pumped with 545-nm pulsed excitation corresponding to the Q transition. In the presence of pump pulses, the aqueous solution of the Cu(TMpy-P4).poly(dA-dT) complex exhibits resonance Raman bands at 1558 and 1353 cm-1 that are not observed in the absence of pump pulses. These new features were previously assigned to electronically excited Cu(TMpy-P4), stabilized by forming an exciplex with the A-T sites of the nucleic acid. Here we present resonance Raman excitation profiles (RREP) of both the excited and ground states of the complex, and we experimentally confirm the very short lifetime of the exciplex. To our knowledge this is the first time that a RREP of a very short lived (ca. 20 ps) intermediate excited state has been obtained with a two-color experiment. We use this to help to characterize the nature of the porphyrin-AT specific complex formed in the porphyrin excited state.

ISOLATION AND PRELIMINARY BIOLOGICAL CHARACTERIZATION OF KPNFIRFAMIDE, A NOVEL FMRFAMIDE-RELATED PEPTIDE FROM THE FREE-LIVING NEMATODE, PANAGRELLUS-REDIVIVUS

A novel FMRFamide-related heptapeptide, Lys-Pro-Asn-Phe-Ile-Arg-Phe-NH2 (KPNFIRFamide), was isolated and characterized from acid ethanol extracts of the free-living nematode, Panagrellus redivivus. Whole-worm extracts contained greater than or equal to 9 pmol KPNFIRFamide/g wet weight. A synthetic replicate of this peptide induced a rapid relaxation of tone and inhibited spontaneous contractility in isolated innervated and denervated body-wall muscle strips of the parasitic nematode, Ascaris suum. KPNFIRFamide (0.1 nM) induced measurable relaxations in 50% of the muscle preparations examined. Concentrations greater than or equal to 0.3 nM induced relaxation in 100% of muscle preparations examined. The relaxation was short-lived at concentrations of peptide greater than or equal to 1 mu M and displayed a profile typical of receptor desensitization. These data suggest the occurrence of a closely related peptide in A. suum and add further evidence to the concept of primary structural conservation of FaRPs within the nematodes.

CROSS-SECTIONS FOR RESONANT TRANSFER AND EXCITATION IN FEQ++H-2 COLLISIONS

Resonant transfer and excitation (RTE) is investigated for Fe(q+) ions (q=23, 24, and 25) colliding with H2. For each charge state, cross sections for RTE were obtained from measurements of K x rays, emitted from the doubly excited intermediate state, coincident with single-electron capture by the incident ion. Additionally, for Fe25+ cross sections were obtained from measurements of coincidences between the two K x rays emitted from the intermediate state. These latter measurements Provide information on the lifetimes of intermediate metastable states formed in the RTE process. In all cases, measured cross sections are in good agreement with calculations based on theoretical cross sections for dielectronic recombination (DR). Since RTE closely approximates DR, the results indicate that dielectronic-recombination cross sections involving K-shell excitation can be accurately predicted for highly charged iron ions. The results for Fe25+ show that metastable states are sufficiently short lived to be observable in the RTE (or DR) process for these hydrogenlike ions.

Surface localisation of photosensitisers on intraocular lens biomaterials for prevention of infectious endophthalmitis and retinal protection

Cataract surgery is one of the most commonly-practiced surgical procedures in Western medicine, and, while complications are rare, the most serious is infectious postoperative endophthalmitis. Bacteria may adhere to the implanted intraocular lens (IOL) and subsequent biofilm formation can lead to a chronic, difficult to treat infection. To date, no method to reduce the incidence of infectious endophthalmitis through bacterial elimination, while retaining optical transparency, has been reported. In this study we report a method to optimise the localisation of a cationic porphyrin at the surface of suitable acrylate copolymers, which is the first point of contact with potential pathogens. The porphyrin catalytically generates short-lived singlet oxygen, in the presence of visible light, which kills adherent bacteria indiscriminately. By restricting the photosensitiser to the surface of the biomaterial, reduction in optical transparency is minimised without affecting efficacy of singlet oxygen production. Hydrogel IOL biomaterials incorporating either methacrylic acid (MAA) or methyl methacrylate (MMA) co-monomers allow tuning of the hydrophobic and anionic properties to optimise the localisation of porphyrin. Physiochemical and antimicrobial properties of the materials have been characterised, giving candidate materials with self-generating, persistent anti-infective character against Gram-positive and Gram-negative organisms. Importantly, incorporation of porphyrin can also serve to protect the retina by filtering damaging shortwave visible light, due to the Soret absorption (?max) 430 nm). © 2012 Elsevier Ltd. All rights reserved.

Diclofenac disposition in Indian cow and goat with reference to Gyps vulture population declines

Gyps vultures across India are declining rapidly and the NSAID diclofenac has been shown to be the major cause. Vultures scavenge livestock carcasses that have been treated with diclofenac within the days preceding death. We present data on diclofenac disposition in Indian cow and goat, and field data on the prevalence of diclofenac in carcases in the environment. In the disposition experiment, animals were treated with a single intramuscular injection of diclofenac at 1000 microg kg-1 bw. In cow, diclofenac was detectable in liver, kidney and intestine up to 71 h post-treatment; in plasma, half-life was 12.2 h. In goat, tissue residues were undetectable after 26 h. Prevalence of diclofenac in liver from 36 dead livestock collected in the field was 13.9%. Data suggest that diclofenac residues in Indian cow and goat are short-lived, but diclofenac prevalence in carcasses available to vultures may still be very high.

Palaeoglacial and palaeoclimatic conditions in the NW Pacific, as revealed by a morphometric analysis of cirques upon the Kamchatka Peninsula

The distribution of glacial cirques upon the Kamchatka peninsula, Far Eastern Russia, is systematically mapped from satellite images and digital elevation model data. A total of 3,758 cirques are identified, 238 of which are occupied by active glaciers. The morphometry of the remaining 3,520 cirques is analysed. These cirques are found to show a very strong N bias in their azimuth (orientation), likely resulting from aspect-related variations in insolation. The strength of this N bias is considered to indicate that former glaciation upon the peninsula was often ‘marginal’, and mainly of cirque-type, with peaks extending little above regional equilibrium-line altitudes. This is supported by the fact that S and SE-facing cirques are the highest in the dataset, suggesting that glacier-cover was rarely sufficient to allow S and SE-facing glaciers to develop at low altitudes. The strength of these azimuth-related variations in cirque altitude is thought to reflect comparatively cloud-free conditions during former periods of glaciation. It is suggested that these characteristics, of marginal glaciation and comparatively cloud-free conditions, reflect the region’s former aridity, which was likely intensified at the global Last Glacial Maximum, and during earlier periods of ice advance, as a result of the development of negative pressure anomalies over the North Pacific (driven by the growth of the Laurentide Ice Sheet), combined with other factors, including an increase in the extent and duration of sea ice, a reduction in global sea levels, cooler sea surface temperatures, and the localised growth of mountain glaciers. There is published evidence to suggest extensive glaciation of the Kamchatka Peninsula at times during the Late Quaternary, yet the data presented here appears to suggest that such phases were comparatively short-lived, and that smaller cirque-type glaciers were generally more characteristic of the period.

Law, Politics and Financial Development: The Great Reversal of the U.K. Corporate Debt Market

This article examines the role of creditor protection in the development of the U.K. corporate bond market. This market grew rapidly in the late nineteenth century, but in the twentieth century it experienced a reversal, albeit with a short-lived post-1945 renaissance. Such was the extent of the reversal that the market from the 1970s onwards was smaller than it had been in 1870. We find that law does not explain the variation in the size of this market over time. Alternatively, our evidence suggests that inflation and taxation policies were major drivers of this market in the post-1945 era. Copyright © The Economic History Association 2013

Polyamine system in developing rat eye and an animal model of retinopathy of prematurity

BACKGROUND: In experimental models of retinopathy of prematurity (ROP), a vasoproliferative disorder of the retina, retinal lesions are usually assessed by morphological examination. However, studies suggest that the polyamine system may be useful in monitoring proliferation processes. For this reason, polyamine concentrations in rat erythrocytes (RBC) and the regulation of polyamine system in rat eyes under the conditions relevant to ROP were investigated. METHODS: Newborn Wistar rats were reared in room air (control) or exposed first to hyperoxia (60% or 80% oxygen, 2 weeks) and then to normoxia (relative hypoxia, 1 or 2 weeks). Blood was collected from orbital vessels at 2 weeks of age and before death. Polyamine system-related enzyme activities were measured in retina and lens with radioassays. Polyamines were quantified by fluorometry after extraction, dansylation and HPLC separation. RESULTS: Oxygen (80% only) significantly decreased RBC polyamine concentrations, which then markedly increased after rats were transferred for a week to normal air, suggesting retardation of growth processes and compensatory stimulation, respectively. However, polyamine system changes in the rat eye were not so pronounced. Enzyme activities and polyamine concentrations tended to be lower in retina after hyperoxia and were only slightly higher, with the exception of ornithine decarboxylase, after a subsequent 1 week of normoxia. In litters subjected to normoxia for longer periods no changes were found. CONCLUSION: The transient and short-lived alteration in polyamine metabolism, especially in the eye, suggests that exposure of newborn rats to high oxygen supplementation followed by normoxia does not necessarily result in marked retinopathy.

Business Giving, the Tsunami and Corporates as Rock Stars: Some Implications for Arts Funding?

Financial and cultural aspects of corporate giving by UK and non-UK companies in response to the December 2004 South Asia Tsunami disaster are explored in this article. Literatures on corporate giving rationales, concepts of disaster and donor activity in disasters provide an underpinning. The article seeks to make connections between this high profile if short-lived business giving and the funding of the arts that is sought from business; and to draw tentative lessons for arts funding when seeking business support. The giving accounts in the wake of the Tsunami from a non-probability sample of 56 UK companies and 16 non-UK companies were examined. Reported online to the UK charity Business in the Community, these accounts were accessed in February 2005 and scrutinized thematically. Concurrently, company financial profiles to accompany giving figures were constructed. Although linkages between donation levels and financial performance were lacking, emerging themes included the role of employees, influencing company giving and creating a climate of expectation of firms' contributions. These developments may have important implications for business funding for the arts, where leading philanthropists are prominent as individuals in the giving landscapes; but employees' collective involvement is not marked. Alternatively, cultivation of employees as would-be donors, indirectly via their firms, may be a more secure, if lower level route to funding for some arts organizations than dependence on high profile business leaders. The article considers alternative scenarios for company giving in disaster contexts, including as a sustained and lasting giving theme or as company support as a ‘one-off’ event, rock-star style. The likely development of employee power as a key element in company giving is explored; and its wider meanings for funding in arts settings, (where the giver as rock star heroine/hero is also prominent) are considered.

Software-Managed Energy-Efficient Hybrid DRAM/NVM Main Memory

This paper evaluates the viability of user-level software management of a hybrid DRAM/NVM main memory system. We propose an operating system (OS) and programming interface to place data from within the user application. We present a profiling tool to help programmers decide on the placement of application data in hybrid memory systems. Cycle-accurate simulation of modified applications confirms that our approach is more energy-efficient than state-of-the- art hardware or OS approaches at equivalent performance. Moreover, our results are validated on several candidate NVM technologies and a wide set of 14 benchmarks.
The key observation behind this work is that, for the work- loads we evaluated, application objects are too short-lived to motivate migration. Utilizing this property significantly reduces the hardware complexity of hybrid memory systems.

The Dynamics of Rapid Redshifted and Blueshifted Excursions in the Solar Hα Line

We analyze high temporal and spatial resolution time-series of spectralscans of the Hα line obtained with the CRisp Imaging SpectroPolarimeter instrument mounted on the Swedish Solar Telescope.The data reveal highly dynamic, dark, short-lived structures known asRapid Redshifted and Blueshifted Excursions (RREs, RBEs) that areon-disk absorption features observed in the red and blue wings ofspectral lines formed in the chromosphere. We study the dynamics of RREsand RBEs by tracking their evolution in space and time, measuring thespeed of the apparent motion, line of sight (LOS) Doppler velocity, andtransverse velocity of individual structures. A statistical study oftheir measured properties shows that RREs and RBEs have similaroccurrence rates, lifetimes, lengths, and widths. They also displaynon-periodic, nonlinear transverse motions perpendicular to their axesat speeds of 4-31 km s-1. Furthermore, both typesof structures either appear as high speed jets and blobs that aredirected outwardly from a magnetic bright point with speeds of50-150 km s-1, or emerge within a few seconds. Astudy of the different velocity components suggests that the transversemotions along the LOS of the chromospheric flux tubes are responsiblefor the formation and appearance of these redshifted/blueshiftedstructures. The short lifetime and fast disappearance of the RREs/RBEssuggests that, similar to type II spicules, they are rapidly heated totransition region or even coronal temperatures. We speculate that theKelvin-Helmholtz instability triggered by observed transversemotions of these structures may be a viable mechanism for their heating.