bluuebunny/crossref_metadata_2025 huggingface dataset:
XXVI.—On a Group of Linear Differential Equations of the 2nd Order, including Professor Chrystal's Seiche-equations
Authors: Halm J.
Published: January 2013

It is readily seen that the two differential equations

which play an important rôle in Professor Chrystal's mathematical theory of the Seiches, are special cases of the more general type

With regard to the first, the Seiche-equation, this becomes at once apparent by writing a= − ½. Equation (2), on the other hand, which we may briefly call the Stokes equation [see Professor Chrystal's paper on “Some further Results in the Mathematical Theory of Seiches,” Proc. Roy. Soc. Edin., vol. xxv.] will be recognised as a special case (a = + 1) of the equation

which is transformed into (3) by the substitution .
XXVIII.—The Plant Remains in the Scottish Peat Mosses
Authors: Lewis Francis J.
Published: January 2013

The following paper deals with an investigation of the successive zones of plant remains contained in the deeper peat deposits covering areas in the Scottish Southern Uplands. The field work was carried on during the summer and early autumn of 1904, and the detailed examination of the peat in the laboratory during part of the winter. No attempt has been made to work out the detailed flora of the different zones, but attention has chiefly been directed to the dominant plant remains found at different horizons in the mosses. Whilst the list of plants from each zone is small, the general facies of the flora of any layer can be gauged from the abundant presence of a few characteristic plants such as Salix reticulata and Empetrum, or Sphagnum and Eriophorum. Thus, while the investigation is incomplete as regards any addition to the history of the British Flora, it will, I hope, throw some light upon the succession of vegetation over the older peat mosses since their origin.
XXXII.—Calculation of the Periods and Nodes of Lochs Earn and Treig, from the Bathymetric Data of the Scottish Lake Survey
Authors: Chrystal  , Maclagan-Wedderburn Ernest
Published: January 2013

§ 1. In a paper published in the present volume of the Transactions of the Society (p. 659, 3rd July 1905), one of the authors of this communication has given a Hydrodynamical Theory of Seiches, and deduced formulae with a view to particular applications. The object of the present paper is to give some account of a series of calculations on which we have been occupied for some time, with a view to work out, a priori, from the Bathymetric Data of the Lake Survey, the Seiche Constants for the three seiches of lowest nodality in Lochs Earn and Treig.

§ 2. As this is the first time that any attempt has been made to solve completely a problem of the kind, we naturally selected lakes having as simple a configuration as possible. A general idea of the shape of the two lakes, and also of the nature of the data from which we have worked, will be obtained from the 3-in. maps reproduced in figures (3) and (4).
XI.—The Pinna-Trace in the Ferns
Authors: Davie R. C.
Published: January 2013

The relation of the leaf-trace to the vascular system of the stem in the Ferns has been exhaustively investigated during the past fifteen years by various workers, especially by Gwynne-Vaughan and Boodle in this country and by Jeffrey and his pupils in America. The interpretations of the numerous types of Fern stele and leaf-trace have caused much discussion. And the discovery of a wonderful series of fossil Ferns has not settled the discussion of the evolution of the Filicinean vascular system, but has carried the battle on to another field.

The fossils have recently yielded up the structure of their pinna-traces (Kidston, '08; Bertrand, '09; Gordon, '11). Simultaneously an attack has been made on the pinna-traces of living Ferns. Various pinna-traces were described in curious mathematical formulæ, but no comparisons were made of the different types, by Bertrand and Cornaille ('02) in their Étude sur quelques caractéristiques de la structure des Filicinées actuelles.
XIII.—Rocks from Gough Island, South Atlantic (collected by the Scottish National AntarcticExpedition, 1902–1904)
Authors: Campbell Robert
Published: January 2013

The specimens described in this paper were collected by Dr J. H. Harvey Pirie, B.Sc, M.B., geologist to the Scottish National Antarctic Expedition, during a short visit paid to Gough Island on the homeward voyage of the Scotia from the Antarctic seas in 1904. The island is not often visited, and the only previous account of the rocks is by Professor L. V. Pirsson, who described a series of beach pebbles collected by the captain of a whaling vessel. Among those Professor Pirsson noted two varieties of basalt, trachytic tuffs, and a trachytic obsidian carrying olivine, and shown by chemical analysis to be of phonolitoid type.

With the exception of a small fragment of limestone, the rocks in the Scotia collection are all igneous. They were obtained in the neighbourhood of the usual landing-place, the mouth of a small glen on the eastward side of the island. They include soda trachytes, trachydolerites, basalts, an essexite, and tuffs.
XV.—Atlantic Sponges collected by the Scottish National Antarctic Expedition
Authors: Stephens Jane
Published: January 2013

The sponges in the following report were collected in the North and South Atlantic during the Scotia's voyages to and from the Antarctic regions in the years 1902–1904.

All the sponges in the collection were obtained off the south-west coast of Cape Colony, with the exception of five well-known species which were taken off St Helena, the Cape Verde Islands, and the Princesse Alice Bank. Only one specimen was dredged in deep water, namely, in 350 fathoms off the Princesse Alice Bank, while the remainder were taken between tide-marks to a depth of 30 fathoms.

The collection contains thirty-five species, of which fifteen are described as new.

To complete the list of sponges obtained by the Scotia in Atlantic waters, mention may be made here of one species which is not contained in this report. This species, Cladorhiza thomsoni, dredged in deep water between Gough Island and the Cape of Good Hope, has been described by Professor Topsent (24 and 25). It was taken at Station 468, 39° 48′ S., 2° 33′ E., depth 2770 fathoms.

The five species above referred to, Leucandra crambessa, Aphrocallistes beatrix, Tethya lyncurium, Chondrosia plebeja and Chondrosia reniformis, call for no special remark. They have all been previously obtained in, or fairly near, the areas for which they are here recorded.
VII.—Electrolytic Synthesis of Dibasic Acids
Authors: Brown Alexander Crum , Walker James
Published: January 2013

Forty years ago Kolbe showed that a strong aqueous solution of potassium acetate, when subjected to the influence of the electric current, is decomposed with formation of the following products. At the anode a gaseous mixture is evolved which consists chiefly of carbonic acid and ethan; while at the cathode hydrogen escapes, and potassium hydrate is formed in the solution. When dilute solutions of the same substance are electrolysed under similar conditions, the decomposition products at the cathode are the same as in the previous case, but at the anode the gas evolved is now oxygen, and free acetic acid makes its appearance in the solution. The difference between the two cases must, on modern views of electrolysis, be attributed to the occurrence of secondary reactions. The primary process is in all cases the transference of the electrically-charged submolecules or ions to the corresponding poles, where they lose their charges, and thereby become capable of reacting with one another or with neighbouring molecules. As a general rule they are, when discharged, themselves incapable of independent existence.
XIII.—On the Solid and Liquid Particles in Clouds
Authors: Aitken John
Published: January 2013

Towards the end of May of this year I made my third visit to the Rigi Kulm, for the purpose of continuing my observations on the amount of dust in the atmosphere and other meteorological phenomena. It was with a feeling of no little satisfaction that I found myself at that elevated situation during broken weather, and under conditions very different from any previously experienced by me. On this occasion I had come in the hope of finding opportunities for making some observations on the conditions existing in clouds, in addition to the usual dust observations, and had brought with me the small instrument for observing the water particles in a fog, described in a previous communication to this Society. As the weather continued to be variable during the week of my visit, I was fortunate enough to succeed in making a number of interesting observations on the water particles in clouds, and also of comparing the conditions in clouds at this elevated situation with those previously observed in fogs at a low level.

Before giving the results of my observations on the water particles, it may be desirable to make a few remarks on the solid or dust particles. When making the ordinary dust observations this year, it was frequently noticed that, when surrounded by clouds, the number of particles varied greatly at short intervals of time.
XX.—A Demonstration of Lagrange's Rule for the Solution of a Linear Partial Differential Equation, with some Historical Remarks on Defective Demonstrations hitherto Current
Authors: Chrystal G.
Published: January 2013

It seems strange that a principle so fundamental and so widely used as Lagrange's Rule for Solving a Linear Differential Equation should hitherto have been almost invariably provided with an inadequate demonstration. I noticed several years ago that the demonstrations in our current English text-books were apparently insufficient; but, as the method by which I treated Linear Partial Differential Equations in my lectures did not involve the use of them, it did not occur to me to analyse them closely with a view to discovering in what the exact nature of the defect consisted. The consideration of certain special cases recently led me to examine the matter more closely, and I was greatly surprised to find that most of the general demonstrations given are vitiated by a very obvious fallacy, and in point of fact do not fit the actual facts disclosed by the examination of particular cases at all.
VIII. Memoir relating to the Naval Tactics of the late John Clerk, Esq. of Eldin; being a Fragment of an intended Account of his Life
Authors: Playfair John
Published: January 2013

The author of the Naval Tactics is one of those men who, by the force of their own genius, have carried great improvements into professions which were not properly their own. The history both of the sciences and of the arts furnishes several remarkable examples of a similar nature. Fermat the rival, sometimes the superior of Descartes, one of the most inventive mathematicians of a most inventive age, was by profession a lawyer, and had only devoted to science the time that could be spared from the duties of a counsellor or a judge: about fifty years earlier, also, his countryman Vieta had made a like digression from the same employment, and hardly with inferior success.

Perrault, who, in the façade of the Louvre, has left behind him so splendid a monument of architectural skill and taste, was a physician, and not only practised, but wrote books on medicine. Dr Herschell too, who has made more astronomical discoveries than any individual of the present age, betook himself to the study of the heavens as a relaxation from professional pursuits.
XV. Description of a Vegetable Impression found in the Quarry of Craigleith
Authors: Allan Thomas
Published: January 2013

I some time ago had the honour to present to the Royal Society, a specimen of a very singular fossil which had been found in the freestone quarry of Craigleith, near this city. It presented the appearance so commonly met with in the sandstone of the coal-formation,—an impression of what has always been considered as the bark of a vegetable connected with the Palm-tribe; but it differed from any thing I had ever before seen of the kind, by having circular marks ranged in a line along the surface, being apparently the impressions of flowers or fruit. As neither of these grow directly from the stem of any plant now known, except among the Cactus genus, this impression might have been referred to it, had not the regularity of distance between these supposed flowers, pointed out the improbability; and it consequently must be referred to some one, the prototype of which is no longer known.

The size of the specimen, of which the annexed engraving is a very exact representation, is twenty-one inches in length, and about fourteen broad; the widest part of the impression measures four inches, and the diameter of the circles a little more than three.
Searching for Type Ia Supernovae in Globular Clusters
Authors: Voss Rasmus
Published: January 2013

Globular clusters are known to have enhanced populations of binaries with compact objects, owing to the dynamical interactions taking place in their dense stellar environments. Both the single degenerate and double degenerate Type Ia supernova progenitors are expected to be similarly enhanced with respect to the field, but the theoretical predictions are highly uncertain. Here we discuss an archival survey aimed at constraining the fraction of Type Ia supernovae that explode inside globular clusters.
Asymptotic Giant Branch Evolution and the Initial-Final Mass Relation of Single CO White Dwarfs
Authors: Marigo Paola
Published: January 2013

Combining recent mass determinations of Galactic CO white dwarfs and their progenitors with the latest evolutionary models for Asymptotic Giant Branch (AGB) stars, I review the initial-final mass relation (IFMR) of low- and intermediate-mass stars. In particular, I analyze the impact on the IFMR produced by a few critical processes characterizing the AGB phase, namely: the second and third dredge-up events, hot-bottom burning, and mass loss. Their dependence on metallicity and related theoretical uncertainties are briefly discussed.
A Single Degenerate Model for Ultra Super-Chandrasekhar Mass Progenitors of Type Ia Supernovae – Young and Low Metallicity Environments –
Authors: Hachisu Izumi , Kato Mariko , Saio Hideyuki , Nomoto Ken'ichi
Published: January 2013

Some Type Ia supernovae (SNe Ia) are suggested to have progenitor white dwarfs (WDs) with mass of up to 2.4–2.8 M⊙, highly exceeding the Chandrasekhar mass limit. We present a new single degenerate (SD) model for SNe Ia progenitors, in which the WD mass can increase by accretion up to 2.3 (2.7) M⊙ from the initial value of 1.1 (1.2) M⊙. The results are consistent with high luminosity SNe Ia such as SN 2003fg, SN 2006gz, SN 2007if, and SN 2009dc. There are three characteristic mass ranges of exploding WDs. In an extreme massive case, differentially rotating WDs explode as a SNe Ia soon after the WD mass exceeds 2.4 M⊙ because of a secular instability at T/|W|~0.14. For a mid mass range of MWD=1.5–2.4 M⊙, which is supported by differential rotation, it takes some spinning-down time until carbon is ignited to induce an SN Ia explosion. For a lower mass range of MWD=1.38–1.5 M⊙, they can be supported by rigid rotation until the angular momentum is lost. We also suggest the ultra super-Chandrasekhar mass SNe Ia are born in young and low metallicity environments.
Swift Observations of Novae
Authors: Page K. L.
Published: January 2013

The rapid response capability of Swift, together with the daily planning of its observing schedule, make it an ideal mission for following novae in the X-ray and UV bands. A number of both classical and recurrent novae have been extensively monitored throughout their supersoft phase. We report findings from these observations, including the high-amplitude flux variation often seen at the start of the supersoft emission, the optical plateau sometimes seen for recurrent novae, the differing relationships between the X-ray and UV variability, and the turn-on and turn-off times of the supersoft emission for the Swift sample of novae.
Spectral Features of KT Eri in its Nebular Phase
Authors: Arai Akira , Isoggai Mizuki , Imamura Kazuyoshi , Ikeda Yuji , Arasaki Takayuki , Kitao Eiji , Taguchi Gaku
Published: January 2013

Non-spherically symmetric distributions of ejected gas are often observed in classical nova remnants. However, it is unclear if these asymmetries could be produced from nova explosions. Spectra in the nebular phase can provide information on the kinematics of ejected materials. Classical nova KT Eri was discovered on November 2009. It is considered a candidate for a recurrent nova based on the high expansion velocity and rapid decline of its light curve. In order to investigate the velocity field of ejected gas in the system, we performed optical spectroscopic observations from 2010 September to 2010 December at Koyama Astronomical Observatory. We noticed the strong [O III] and He II lines in the spectra on September 1, which suggests that the nova had already entered the nebular phase. It is notable that the [O III] lines showed complex profiles with at least six peaks on September 1. Those features can be de-convolved into four velocity components (−2,000 km s−1, −1,000 km s−1, +700 km s−1, and +1,800 km s−1) of doublet [O III] λ4959 and λ5007.
High Resolution XMM-Newton Data of Nova Outbursts using Warm & Hot Absorber Models
Authors: Balman Ş. , Pekön Y.
Published: January 2013

We reanalyze a selection of the XMM-Newton RGS (Reflection Grating Spectrometer) data of two classical novae; V4743 Sgr and V2491 Cyg. The high resolution nova spectra in the X-ray wavelengths show existence of absorption features (e.g., blue shifted). Our main aim is to model the absorption components detected in the high resolution spectra independently from the assumed continuum model. We assume that there is complex absorption of interstellar, photospheric, and of collisionally and/or photoionized gas origin in the moving material along the line of sight from a nova wind or ejecta. In addition to deriving the absorption properties, we obtain CNO abundances of elements in the ejecta/nova wind.
Symbiotic Stars as Possible Progenitors of SNe Ia: Binary Parameters and Overall Outlook
Authors: Mikołajewska J.
Published: January 2013

Symbiotic stars are interacting binaries in which the first-formed white dwarf accretes and burns material from a red giant companion. This paper aims at presenting physical characteristics of these objects and discussing their possible link with progenitors of Type Ia supernovae.
Hydrodynamic Studies of the Evolution of Recurrent Novae to Supernova Ia Explosions
Authors: Starrfield S. , Timmes F. X. , Hix W. R. , Iliadis C. , Arnett W. D. , Meakin C. , Sparks W. M.
Published: January 2013

We have begun new studies of the evolution of thermonuclear runaways (TNRs) in the accreted envelopes of white dwarfs (WDs). Here we focus on the recent outbursts of RS Oph (2006), U Sco (2010) and T Pyx (2011). U Sco explodes about every 10 years and the ejected material from the WD is helium rich. It has a short orbital period for recurrent novae (RNe) but the secondary is likely to be evolved. The WD is thought to be close in mass to the Chandrasekhar limit. T Pyx has just suffered its first outburst since 1966 and it was predicted to never experience another outburst. It has a short orbital period and has formed dust in the ejecta as this paper was being written. One important question is the secular evolution of the WD. Do the repeated outbursts cause the WD to gain or lose mass? If it is gaining mass, it could eventually reach the Chandrasekhar limit and become a Type Ia supernova (SNe Ia) if it can hide the hydrogen and helium in the system. Here, we report on our latest studies of TNRs in accreted envelopes on WDs using a variety of initial WD masses, luminosities, and mass accretion rates. Of great importance to our conclusions, we assume a solar composition (Lodders abundance distribution). We use our 1-D hydro code, NOVA, that includes the Hix and Thielemann nuclear reaction network, the Iliadis reaction rate library, the Timmes equation of state, OPAL opacities, and the new convection of Arnett, Meakin, and Young. We report on the amount of ejected mass, evolution time to explode, and whether or not the WD is growing or losing mass.
X-ray Grating Observations of Recent Recurrent Novae
Authors: Orio Marina , Behar Ehud , Gallagher J. , Bianchini A. , Chiosi E. , Luna J. , Nelson T. , Rauch T.
Published: January 2013

Two recurrent novae (RNe) that do not host red giants were observed in outburst at the beginning of 2009 and 2010, respectively. The first nova was LMC 2009a, and the second one was U Scorpii. Nova LMC 2009a was a relatively slow RN, and it was quite luminous both at optical and X-ray wavelengths. U Sco is the fastest nova ever recorded. Its supersoft X-ray phase started a couple of weeks after optical maximum and lasted for about a month, while for Nova LMC 2009a this phase started four months after maximum and lasted for 5 months. For both novae, the first X-ray spectrum taken while the luminous supersoft X-ray source was beginning to emerge is remarkably similar with broad and prominent emission lines of nitrogen and carbon accounting for at least 30% of the X-ray flux. Blue-shifted absorption and red-shifted emission form apparent P-Cyg profiles. We attribute the emission features to the ejecta and show evidence that they are largely due to collisional ionization. In the case of U Sco the absorption lines were embedded in the emission features after the first observation. We find evidence that in U Scorpii we were observing the Thomson reflected spectrum at a distance of ≃ 3 R⊙ from the white dwarf rather than the atmosphere itself. For both novae, the peak temperature was remarkably high, probably close to 900,000 K for U Sco, and about 600,000 K for Nova LMC 2009a. We suggest that these two objects represent different stages of RNe secular evolution.
The Asymmetric Outflow of RS Ophiuchi
Authors: Mohamed S. , Booth R. , Podsiadlowski Ph.
Published: January 2013

RS Ophiuchi (RS Oph) is a symbiotic binary consisting of a hot white dwarf accreting from the slow, dense stellar wind of a cool, red giant companion. The system belongs to, and is one of the best studied examples of, an even smaller subclass of binaries known as recurrent novae in which the white dwarf undergoes repeated thermonuclear outbursts. We present 3D smoothed particle hydrodynamics (SPH) models of mass transfer from the red giant to the white dwarf, followed by a nova outburst. We show that the outflow in the former is strongly concentrated towards the binary orbital plane. The nova ejecta is thus constrained in the equatorial directions, resulting in a bipolar outflow. The white dwarf in RS Oph is thought to be close to the Chandrasekhar mass, making the system a likely Type Ia supernova candidate. We discuss the role that such a highly structured circumstellar medium will play in the evolution of the supernova remnant.
Changes in the Dusty Environment of the Recurrent Nova RS Ophiuchi
Authors: Rushton M. T. , Helton L. A. , Kaminsky B. , Woodward C. E. , Pavlenko Ya. V. , Evans A.
Published: January 2013

We present Spitzer spectroscopy of the recurrent nova RS Ophiuchi obtained on several occasions between 2006 and 2009. The spectra show variability in the silicate dust features at 9.7 μm and 18 μm, which form in the wind of the red giant in the system. We fit the spectra with Dusty models and find changes in the dust temperature, due to changes in the luminosity of the central source. The mass-loss rate of the secondary is a few 10−7M⊙yr−1, typical of a red giant of its type.
Modeling of the IR Light Curves of the Symbiotic Recurrent Nova T CrB
Authors: Tatarnikova A. A. , Tatarnikov A. M. , Shenavrin V. I.
Published: January 2013

We analyze the results of our IR photometric monitoring of T CrB during 1987-2003 and describe the ellipsoidal variability of the Roche lobe filling cool component. We obtain limits to the binary inclination of i ∈ [50,60] deg and binary mass ratio q ∈ [0.4,2] (90 per cent confidence). The mass of the hot component is therefore 1.3-3 M⊙. If the hot component of T CrB is a white dwarf, its mass will be near the Chandrasekhar limit.
Survey for the Binary Progenitor in SN1006 and Update on SN1572
Authors: Ruiz–Lapuente Pilar , Hernández Jonay González , Tabernero Hugo , Montes David , Canal Ramon , Mendez Javier , Bedin Luigi
Published: January 2013

We have completed a survey down to R = 15 mag of the stars within a circle of 4 arcmin radius around the nominal center of the remnant of SN 1006, one of the three historical Type Ia supernovae (the other two being SN 1572 and SN 1604), in search of a possible surviving binary companion of the white dwarf whose explosion gave rise to the supernova. The stellar parameters (effective temperature, surface gravity, and metallicity), as well as the radial velocities of all the stars, have been measured from spectra obtained with the UVES spectrograph at the VLT, and from the former and the available photometry, distances have been determined. Chemical abundances of the Fe-peak elements Cr, Mn, Co, and Ni have also been measured to check for possible contamination of the stellar surface by the supernova ejecta. The limiting magnitude of the survey would allow us to find stellar companions of the red-giant type, subgiant stars, and main–sequence stars down to F5–6. Unlike in SN 1572, where a subgiant of type G0–1 has been proposed as the companion of SN 1572, for SN 1006 we can discard the possibility that SN 1006 had a red giant or subgiant companion.
Light-Echo Spectrum Reveals the Type of Tycho Brahe's 1572 Supernova
Authors: Usuda T. , Krause O. , Tanaka M. , Hattori T. , Goto M. , Birkmann S. M. , Nomoto K.
Published: January 2013

We successfully obtained the first optical spectra of the faint light echoes around Cassiopeia A and Tycho Brahe's supernova remnants (SNRs) with FOCAS and the Subaru Telescope. We conclude that Cas A and Tycho's SN 1572 belong to the Type IIb and normal Type Ia supernovae, respectively. Light echo spectra are important in order to obtain further insight into the supernova explosion mechanism of Tycho's SN 1572: how the Type Ia explosion actually proceeds, and whether accretion occurs from a companion or by the merging of two white dwarfs. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. Future light-echo spectra, obtained in different spatial directions of SN 1572, will enable to construct a three-dimensional spectroscopic view of the explosion.
A sclerite-bearing stem group entoproct from the early Cambrian and its implications
Authors: Zhang Zhifei , Holmer Lars E. , Skovsted Christian B. , Brock Glenn A. , Budd Graham E. , Fu Dongjing , Zhang Xingliang , Shu Degan , Han Jian , Liu Jianni , Wang Haizhou , Butler Aodhán , Li Guoxiang
Published: January 2013

The Lophotrochozoa includes disparate tentacle-bearing sessile protostome animals, which apparently appeared in the Cambrian explosion, but lack an uncontested fossil record. Here we describe abundant well preserved material of Cotyledion tylodes Luo et Hu, 1999, from the Cambrian (Series 2) Chengjiang deposits, reinterpreted here as a stem-group entoproct. The entoproct affinity is supported by the sessile body plan and interior soft anatomy. The body consists of an upper calyx and a lower elongate stalk with a distal holdfast. The soft anatomy includes a U-shaped gut with a mouth and aboral anus ringed by retractable marginal tentacles. Cotyledion differs from extant entoprocts in being larger and having the calyx and the stalk covered by numerous loosely-spaced external sclerites. The description of entoprocts from the Chengjiang biota traces the ancestry of yet another lophotrochozoan phylum back to the Cambrian radiation and has important implications for the earliest evolution of lophotrochozoans.
Influence of data clustering on in‐order multi‐core processing systems
Authors: Claeys D. , Bruneel H. , Steyaert B. , Mélange W. , Walraevens J.
Published: January 2013

In multi‐core in‐order processing systems, only one core can be utilised when the instruction at the head of the instruction queue produces data input for the next instruction in the queue. Although in‐order processing has been studied in the past, the influence of data clustering, i.e. the extent to which subsequent instructions rely on each other's data, has been largely overlooked. Therefore a queueing model is developed and closed‐form formulae are provided for the stability condition and the average time before instructions are executed. These expressions clearly reflect that data clustering can have a devastating impact.
Sub‐optimal precoding scheme for distributed antenna systems in correlated Rayleigh channel
Authors: Yu X. , Xu J. , Luo Z. , Chen X.
Published: January 2013

A sub‐optimal precoding scheme for distributed antenna systems in a spatially correlated Rayleigh channel is developed by asymptotical analysis at low and high SNRs. A Newton's method based practical iterative algorithm is presented to find the power allocation coefficients in this scheme. Compared to the existing optimal scheme which requires multidimensional roots finding, the scheme developed in this reported work only needs one‐dimensional root finding, and thus it has lower calculation complexity. Moreover, it can converge to the solution quickly, and obtain a performance close to a optimal scheme. Simulation results corroborate the effectiveness of the developed scheme.
Robust Capon beamforming in presence of large DOA mismatch
Authors: Zhang W. , Wu S. , Wang J.
Published: January 2013

In the presence of significant direction‐of‐arrival (DOA) mismatch, a robust Capon beamforming approach is proposed. The basic idea of the proposed method is first to estimate a set of the desired steering vectors corresponding to DOAs coming from a DOA uncertainty region by using the uncertainty set based approach, then a Bayesian approach is employed to obtain the weight vector.
Method for electric field and potential calculations in Hall plates
Authors: Raman J. , Rombouts P. , Weyten L.
Published: January 2013

Electrostatic field problems occurring in Hall plates are difficult to solve, mainly because of a non‐standard boundary condition defining an oblique angle of the electric field w.r.t. an isolating boundary. A new approach for solving Hall‐related field problems is presented. Compared to prior approaches, the technique leads more easily to closed‐form expressions for the electric field, and allows obtaining voltage‐related Hall characteristics in numerically well conditioned forms.
1180 nm VECSEL with output power beyond 20 W
Authors: Ranta S. , Tavast M. , Leinonen T. , Van Lieu N. , Fetzer G. , Guina M.
Published: January 2013

The highest power result for an optically‐pumped single‐chip vertical external‐cavity surface‐emitting laser with emission near 1180 nm is reported. The gain mirror was grown by molecular beam epitaxy and incorporated a strain compensated GaInAs/GaAs/GaAsP active region. An intra‐cavity diamond heat spreader was attached to the gain mirror for thermal management. In free‐running operation, the laser emitted more than 20 W at a mount temperature of about 12 °C. The output spectrum was centred between 1165–1190 nm depending on the mount temperature and pump power. By using an intra‐cavity birefringent filter, the full width at half‐maximum linewidth could be narrowed to ≤1 nm and at the same time achieved approximately 14 W of output power near 1178 nm. Moreover, the lasing wavelength could be tuned over more than 40 nm.
Intensity noise in normal‐pumped picosecond supercontinuum generation, where higher‐order Raman lines cross into anomalous dispersion regime
Authors: Møller U. , Bang O.
Published: January 2013

The relative intensity noise (RIN) properties at different wavelengths and power levels for picosecond supercontinuum (SC) generated by pumping a PCF in its normal dispersion regime is investigated. For low power levels the all‐normal SC is generated while the generated SC extends beyond the zero dispersion wavelength (ZDW) at high power levels. The RIN measurements are compared with a red‐edge matched SC generated in a highly nonlinear PCF pumped in the anomalous dispersion regime close to its ZDW.
Robust audio hashing scheme based on cochleagram and cross recurrence analysis
Authors: Chen N. , Xiao H.D. , Zhu J. , Lin J.J. , Wang Y. , Yuan W.H.
Published: January 2013

A robust hashing method based on computer‐vision techniques is proposed as an improvement to the existing computer‐vision based hashing scheme. The cochleagram of the audio is treated as an image, from which Speeded Up Robust Features are extracted as essential features. Non‐negative matrix factorisation is used to reduce the features’ dimension. In hashing matching, recurrence quantification analysis is performed on the cross recurrence plot that is constructed from the essentialfeatures of two clips to measure their similarity. Experimental results illustrate that the proposed method exhibits superior performance compared to existing techniques in identification rate (under various content preserving manipulations) and computational complexity.
Accuracy‐enhanced switched‐capacitor stages using low‐gain opamps
Authors: Zhang Y. , Chen C.‐H. , Temes G.C.
Published: January 2013

A charge compensation technique is proposed for switched capacitor stages with low‐gain opamps. It cancels the error charge flow during the operation phase, thus enhancing the accuracy. A capacitive T‐network can be employed to implement the resulting large capacitor ratio. A switched‐capacitor integrator and a sample‐and‐hold stage were designed and simulated to verify the proposed technique.
Rate‐distortion performance‐invariant early termination algorithm for depth coding
Authors: Ma X. , Huo J. , Yang X. , Ren G.
Published: January 2013

An efficient early termination algorithm for depth coding is presented by considering the textureless characteristic of depth maps. In the proposed algorithm, all candidate modes are sorted in ascending order according to their inherent minimum rate‐distortion costs (IMRDcost), resulting from the minimum number of head information coding bits. After finishing the rate‐distortion cost (RDcost) calculation of each candidate mode, a termination decision will be made with IMRDcost of the next candidate mode to decide whether or not to terminate the mode decision process. Experimental results show that the algorithm can save encoding time by 84.20% on average, while the rate‐distortion performance is invariant.
Double split ring slot FSS reflectarray for difference pattern generation
Authors: Zelenchuk D. , Fusco V.
Published: January 2013

A report is presented on a split ring slot frequency selective surface (FSS) reflector whose element design and distribution allows generation of far‐field difference patterns. The reflector operates by converting linearly polarised plane wave fronts into two orthogonal polarisations each with a deep null in the centre of the radiation pattern. The far‐field measurement presented is in good agreement with the simulation and demonstrates a null depth of −20dB in the centre of the radiation pattern.
Wide stopband substrate integrated waveguide filter using corner cavities
Authors: Zhu F. , Hong W. , Chen J.X. , Wu K.
Published: January 2013

A type of substrate integrated waveguide (SIW) ‘corner cavity’ is proposed. For each corner cavity, two transmission zeros (TZs) can be introduced and the location of either TZ can easily be controlled by adjusting suitable geometrical parameters. Using the corner cavities, a novel SIW filter with wide stopband characteristic is implemented. The central frequency of the filter is 20 GHz, and the first spurious appears at about 40 GHz, which is two times the central frequency. In addition, the measured stopband attenuation of the filter is better than 50 dB from 21.24 to 37.71 GHz.
Knitted, textile, high impedance surface with integrated conducting vias
Authors: Tennant A. , Hurley W. , Dias T.
Published: January 2013

An experimental, microwave high impedance surface (HIS) manufactured from a combination of both conducting and insulating yarns using commercial, computerised flat‐bed knitting machines is presented. The HIS consists of a knitted, conducting ground plane, a polyester spacer layer and a knitted, conducting patterned top surface. The structure also contains vias that link the conducting elements of the top layer to the ground plane. The entire structure (including the vias) is knitted in one continuous process that is both low cost and highly efficient in terms of manufacturing time. Measurements of the surface wave transmission properties of the knitted, textile HIS are made and data are presented that show that the HIS prevents surface wave transmission over a band of frequencies between 4 and 5GHz.
High‐power‐tolerant InAlAs avalanche photodiode for 25 Gbit/s applications
Authors: Nada M. , Muramoto Y. , Yokoyama H. , Ishibashi T. , Matsuzaki H.
Published: January 2013

A wide optical‐input dynamic range is demonstrated for an inverted p‐down InAlAs/InGaAs avalanche photodiode. The 3 dB down bandwidth maintains a value as high as 18 GHz for an input optical power level of up to + 2.5 dBm. Such high‐power tolerance meets the requirements of various future optical fibre communications systems such as 100 Gbit/s Ethernet which has a serial baud rate of 25 Gbit/s.
Non-equivalent carbon atoms in the resonant inelastic soft X-ray scattering map of cysteine
Authors: Meyer F. , Weinhardt L. , Blum M. , Bär M. , Wilks R. G. , Yang W. , Heske C. , Reinert F.
Published: January 2013

Resonant inelastic soft x-ray scattering (RIXS) was used to study the electronic structure of solid cysteine films. A RIXS map approach, i.e., plotting the x-ray emission intensity as a function of excitation and emission energy, allows us to separate the contributions of the three chemically non-equivalent carbon atoms in cysteine. In particular, we can identify orbitals localized near the photoexcited atoms, as well as orbitals that are delocalized over the entire molecule.
Direct determination of exciton couplings from subsystem time-dependent density-functional theory within the Tamm–Dancoff approximation
Authors: König Carolin , Schlüter Nicolas , Neugebauer Johannes
Published: January 2013

In subsystem time-dependent density functional theory (TDDFT) [J. Neugebauer, J. Chem. Phys. 126, 134116 (2007)10.1063/1.2713754] localized excitations are used to calculate delocalized excitations in large chromophore aggregates. We have extended this formalism to allow for the Tamm–Dancoff approximation (TDA). The resulting response equations have a form similar to a perturbative configuration interaction singles (CIS) approach. Thus, the inter-subsystem matrix elements in subsystem TDA can, in contrast to the full subsystem-TDDFT case, directly be interpreted as exciton coupling matrix elements. Here, we present the underlying theory of subsystem TDDFT within the TDA as well as first applications. Since for some classes of pigments, such as linear polyenes and carotenoids, TDA has been reported to perform better than full TDDFT, we also report applications of this formalism to exciton couplings in dimers of such pigments and in mixed bacteriochlorophyll–carotenoid systems. The improved description of the exciton couplings can be traced back to a more balanced description of the involved local excitations.
Using fixed-node diffusion Monte Carlo to investigate the effects of rotation-vibration coupling in highly fluxional asymmetric top molecules: Application to H2D+
Authors: Petit Andrew S. , Wellen Bethany A. , McCoy Anne B.
Published: January 2013

A fixed-node diffusion Monte Carlo approach for obtaining the energies and wave functions of the rotationally excited states of asymmetric top molecules that undergo large amplitude, zero-point vibrational motions is reported. The nodal surfaces required to introduce rotational excitation into the diffusion Monte Carlo calculations are obtained from the roots of the asymmetric top rigid rotor wave functions calculated using the system's zero-point, vibrationally averaged rotational constants. Using H2D+ as a model system, the overall accuracy of the methodology is tested by comparing to the results of converged variational calculations. The ability of the fixed-node diffusion Monte Carlo approach to provide insights into the nature and strength of the rotation-vibration coupling present in the rotationally excited states of highly fluxional asymmetric tops is discussed. Finally, the sensitivity of the methodology to the details of its implementation, such as the choice of embedding scheme, is explored.
Probing the hydrogen equilibrium and kinetics in zeolite imidazolate frameworks via molecular dynamics and quasi-elastic neutron scattering experiments
Authors: Pantatosaki Evangelia , Jobic Hervé , Kolokolov Daniil I. , Karmakar Shilpi , Biniwale Rajesh , Papadopoulos George K.
Published: January 2013

The problem of simulating processes involving equilibria and dynamics of guest sorbates within zeolitic imidazolate frameworks (ZIF) by means of molecular dynamics (MD) computer experiments is of growing importance because of the promising role of ZIFs as molecular “traps” for clean energy applications. A key issue for validating such an atomistic modeling attempt is the possibility of comparing the MD results, with real experiments being able to capture analogous space and time scales to the ones pertained to the computer experiments. In the present study, this prerequisite is fulfilled through the quasi-elastic neutron scattering technique (QENS) for measuring self-diffusivity, by elaborating the incoherent scattering signal of hydrogen nuclei. QENS and MD experiments were performed in parallel to probe the hydrogen motion, for the first time in ZIF members. The predicted and measured dynamics behaviors show considerable concentration variation of the hydrogen self-diffusion coefficient in the two topologically different ZIF pore networks of this study, the ZIF-3 and ZIF-8. Modeling options such as the flexibility of the entire matrix versus a rigid framework version, the mobility of the imidazolate ligand, and the inclusion of quantum mechanical effects in the potential functions were examined in detail for the sorption thermodynamics and kinetics of hydrogen and also of deuterium, by employing MD combined with Widom averaging towards studying phase equilibria. The latter methodology ensures a rigorous and efficient way for post-processing the dynamics trajectory, thereby avoiding stochastic moves via Monte Carlo simulation, over the large number of configurational degrees of freedom a nonrigid framework encompasses.
Tunnel-field-effect-transistor based gas-sensor: Introducing gas detection with a quantum-mechanical transducer
Authors: Sarkar Deblina , Gossner Harald , Hansch Walter , Banerjee Kaustav
Published: January 2013

A gas-sensor based on tunnel-field-effect-transistor (TFET) is proposed that leverages the unique current injection mechanism in the form of quantum-mechanical band-to-band tunneling to achieve substantially improved performance compared to conventional metal-oxide-semiconductor field-effect-transistors (MOSFETs) for detection of gas species under ambient conditions. While nonlocal phonon-assisted tunneling model is used for detailed device simulations, in order to provide better physical insights, analytical formula for sensitivity is derived for both metal as well as organic conducting polymer based sensing elements. Analytical derivations are also presented for capturing the effects of temperature on sensor performance. Combining the developed analytical and numerical models, intricate properties of the sensor such as gate bias dependence of sensitivity, relationship between the required work-function modulation and subthreshold swing, counter-intuitive increase in threshold voltage for MOSFETs and reduction in tunneling probability for TFETs with temperature are explained. It is shown that TFET gas-sensors can not only lead to more than 10 000× increase in sensitivity but also provide design flexibility and immunity against screening of work-function modulation through non-specific gases as well as ensure stable operation under temperature variations.
Lattice summations for spread out particles: Applications to neutral and charged systems
Authors: Heyes D. M. , Brańka A. C.
Published: January 2013

This work is concerned with the lattice energy of periodic assemblies of mass and charge distributions of the form, exp (−αp2), where α is an adjustable positive variable and \documentclass[12pt]{minimal}\begin{document}${\underline{p}}$\end{document}p̲ is the vector from the lattice site or average position. The energy of interaction between two distributions is the density-weighted integral of the interactions between the volume elements of each distribution. Reciprocal space lattice summation formulas derived for particles represented by gaussian smeared-out density distributions are applied to the gaussian potential and a bounded version of the soft-sphere potential for a range of exponents. Two types of spatial broadening are considered, continuous or physical broadening (PB) and broadening resulting from the time average of point particle positions, so-called “time” broadening (TB). For neutral mass distributions a reciprocal space lattice summation formula is derived which is applied to the bounded soft-sphere potential. For the charged systems, the methodology described in Heyes [J. Chem. Phys. 74, 1924 (1981)10.1063/1.441285] is used, which for the PB case gives the Ewald-like formulas derived by Gingrich and Wilson [Chem. Phys. Lett. 500, 178 (2010)10.1016/j.cplett.2010.10.010] using a different method. Another expression for the lattice energy of the spread out charge distributions is derived which is cast entirely in terms of a summation over the reciprocal lattice vectors, without the arbitrary charge spreading function used in the Ewald method. The effects of charge spreading on a generalized definition of the Madelung constant (M) for a selection of crystal lattices are shown to be insignificant for route mean square displacements up to values typical of melting of an ionic crystal. When the length scale of the charge distribution becomes comparable to or greater than the mean inter particle spacing, however, the effects of charge broadening on the lattice energy are shown to be significant. In the PB case, M → 0 for the uniform charge density or α → 0 limit, and M ultimately becomes negative in the TB case for a large enough root mean square displacement (or small enough α).
Surface effects on the optical and photocatalytic properties of graphene-like ZnO:Eu3+ nanosheets
Authors: Yang Lili , Wang Zhe , Zhang Zhiqiang , Sun Yunfei , Gao Ming , Yang Jinghai , Yan Yongsheng
Published: January 2013

The graphene-like ZnO:Eu3+ (ZEO) nanosheets with different Eu3+ doping concentrations are synthesized successfully by a simple hydrothermal method. We utilize the native surface effect in the ZEO nanosheets for the first time to certify the resonant energy transfer mechanism from the ZnO host to the Eu3+ ions by means of the power-dependent photoluminescence technique. Meanwhile, to further explore the functional applications of the graphene-like ZEO, we also characterize their photocatalytic activity on the Rhodamine B dye and reveal that both the higher specific surface area and Eu3+ doping lead to the higher degradation efficiency of ZEO nanosheets.