bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization and role of tyrosinases in the lichenLobaria pulmonaria(L.) Hoffm.
Authors: MATEE Lusanda P. , BECKETT Richard P. , SOLHAUG Knut A. , MINIBAYEVA Farida V. 
Published: July 2016

AbstractTyrosinases are a widespread family of multicopper oxidase enzymes. In our earlier work, we identified the presence of tyrosinases in lichenized Ascomycetes based on their substratum specificity, sensitivity to inhibitors and molecular mass. Here, we present a more detailed characterization of a tyrosinase from the lichenLobaria pulmonaria. We also compare tyrosinase activity with the activities of laccases and peroxidases, the other redox enzymes present in this species. The importance of tyrosinases in lichen biology was studied by testing their role in melanin synthesis. Laboratory experiments clearly showed that tyrosinases fromL. pulmonariaresemble those from other lichens and in free-living fungi. While the tyrosinases can metabolize the melanin precursor L-DOPA, L-DOPA can also be metabolized by peroxidases and laccases. A field experiment showed that exposing shade-adaptedL. pulmonariato normal solar radiation induces L-DOPA melanin synthesis. Synthesis occurred when lichens were exposed to either direct sunlight, or placed under a wavelength-neutral filter that slightly reduced overall light. In lichens receiving unfiltered sunlight, melanin synthesis was accompanied by increased laccase activity; by contrast, no changes in enzyme activity occurred in lichens placed under the wavelength-neutral filter. Melanization was reduced by placing lichens under filters that removed UV-B, and prevented by filters that removed both UV-A and UV-B. Removing UV-B had no effect on enzyme activity, whereas removing both UV-A and UV-B increased tyrosinase activity. Results from this study indicate that under some conditions laccases may be involved in melanin synthesis, but they provide no evidence for a role for tyrosinases in melanization. Although high tyrosinase activities are widespread in lichens, many questions on the role of this enzyme in lichen biology remain to be answered.
Burton Park, Sussex: A Further Note
Authors: Hudson Timothy P. 
Published: July 2016

The mission at Burton Park in West Sussex has been most recently discussed by Fr. Geoffrey Holt in Recusant History 13 (1975). A few amplifications and corrections can, however, be made from sources not known to him.First, the position within the Elizabethan house of the chapel that served the mission until the early nineteenth century can be identified from a local newspaper report of 1826. Successive manor houses at Burton occupied the same site, pace the speculations reported by Fr. Holt. A curious feature of that site was that at one time it straddled the boundary between Burton and Barlavington parishes (Fig. 1); the medieval house was evidently in the former and expanded eastwards into the latter. The Elizabethan house, which survived until the early nineteenth century, had at least two courtyards, of which the westemmost lay eighty metres south of Burton parish church and had an elaborate frontispiece, known from a drawing by Grimm. The east end of the house was rebuilt in the eighteenth century by the Venetian architect Giacomo Leoni, with a fine classical façade and a notable saloon and drawing room, but in 1826 the building was largely destroyed by fire caused by a servant girl's carelessness. The report of the event in the Brighton Herald states that the chapel was at the west end, which together with the centre of the building was the part that was burnt.
Mille Maeandris: Nicholas Owen, 1606–2006
Authors: Hodgetts Michael 
Published: July 2016

Nicholas Owen, the master-builder of priest-holes, latibulorum egregius artifex, died of torture in the Tower on the night of 1–2 March 1606. A few months later, the Jesuit John Gerard, who owed his life at least four times to hides constructed by Owen, wrote in his Narrative of the Gunpowder Plot:He might have made it almost an impossible thing for priests to escape, knowing the residences of most priests in England, and of all those of the Society, whom he might have taken as partridges in a net, knowing all their secret places which himself had made, and the like conveyances in most of the chief Catholics’ houses in England, and the means and manner how all such places were to be found, though made by others.
XI.—Quantum Theory of the Chemical Bond
Authors: Coulson C. A. 
Published: July 2016

SummaryWave mechanics is able to describe with some precision the motions of electrons in atoms, but when we study molecules we have to use more approximate descriptions. It turns out that what the chemist is accustomed to call a single bond is in reality a pair of electrons, having opposed spins, describing equivalent orbits which have symmetry about the line joining the two nuclei concerned; this may be called a localised bond. The tetrahedral character of the bonds from saturated Carbon atoms are easily fitted into this scheme.In Ethylene, however, another type of orbit appears; this is the double-streamer orbit, and two electrons in this orbit convert a normal single bond into a double bond. Again the bond is a localised bond, with a characteristic energy and length.In more complex molecules, such as Benzene, there is a framework of single bonds, and the remaining electrons have orbits that embrace all six of the Carbon atoms; these mobile electrons give the aromatic and conjugated molecules their characteristic properties, but as a result the bonds are neither pure single bonds nor pure double bonds, but a hybrid of the two, and the electrons in these bonds are no longer localised in the region between any two particular nuclei. The energies of these molecules can be calculated in fair agreement with experiment, and from a knowledge of the wave function it is possible to define an order, which is usually fractional, for these bonds. In Benzene all the C-C links are equivalent, and their order is I⅔.A curve which connects the fractional order with the length of the bond enables us to predict the lengths of these bonds, and, where experimental comparison is available, agreement is found. These mobile electrons are important in a study of vibration frequencies, restricted rotation about C-C bonds, and in polymerisation.
XIII.—A Problem in the Random Distribution of Particles
Authors: Eggleton Philip , Kermack William Ogilvie 
Published: July 2016

Summary1.An n : l is defined as a group of n particles which can be contained within a seeker length l moving around a closed line of length L on which N particles are distributed at random. An expression has been obtained for the average number of distinct n : l's per closed line.2.An expression has also been derived for the average numbers of n : l's in the corresponding problem where the line of length L containing the N particles is open and not closed.3.Analogous problems in two dimensions are considered, in which the particles are arranged at random on a plane and the place of the seeker line is taken by an orientated rectangle. Exact expressions are given for the desired averages.4.The extension of the methods used to analogous problems in three dimensions is discussed. Exact expressions have not been obtained, but approximations are given which hold when n is much greater or much smaller than x, the average number found within the seeker area.
XVII.—The Regraduation of Clocks in Spherically Symmetric Space-times of General Relativity.
Authors: McVittie G. C. 
Published: July 2016

SummaryThe changes in his description of events brought about by an arbitrary regraduation of an observer's clock are examined, taking the axioms of general relativity as fundamental. It is shown that regraduation does not imply a change from one Riemannian space-time to another but merely a coordinate transformation within space-time. A generalisation of the “dynamical time” of kinematical relativity is a by-product of the investigation.
XXIII.—The Number of the Elements
Authors: Feather N. 
Published: July 2016

SummaryThe development of the idea of the chemical element is traced from its early beginnings, and the importance for this development of the Newtonian concept of invariable mass is emphasised. The emergence of the nuclear atom model is outlined, and the discovery of the complex (isotopic) nature of the majority of known chemical elements is described. Nuclear charge (Z) and mass (A) numbers are defined. Previously recognised regularities concerning mass and charge numbers of existing stable species are shown to have exact counterparts in regularities relating to the degree of instability (as measured by the energy of disintegration) of β-active species (“naturally” and “artificially” radioactive species). Naturally occurring a-active species are regarded as the analogues of the stable species for charge numbers greater than 83, and for charge numbers both greater and less than this value the limitation to the number of stable or quasi-stable isotopes of a given element (limitation of A values for a given Z) is established as essentially a question of nuclear stability as against β-emission (positive and negative electron emission). Finally, reasons are given for supposing that the number of possible chemical elements is limited (limitation to Z in the direction of Z increasing) by the susceptibility to spontaneous nuclear fission of species of sufficiently high nuclear charge.
XXXIII.—Applications of Elliptic Functions to Wind Tunnel Interference
Authors: Milne-Thomson L. M. 
Published: July 2016

SummaryA general formula is obtained for the interference velocity when an aerofoil with elliptically distributed circulation is in a closed or open wind tunnel of any cross-section. The mapping of the section on the interior of a circle is given in terms of the Jacobian elliptic functions appropriate to the ellipse and rectangle. The result is worked out for an aerofoil which spans the focal distance in a tunnel whose section is an ellipse.
XXXV.—Graphite Crystals and Crystallites. I. Binding Energies in Small Crystal Layers
Authors: Bradburn Mary , Coulson C. A. , Rushbrooke G. S. 
Published: July 2016

SummaryCalculations are made of the resonance energy, bond order and bond length in a series of graphitic layers of varying size. Carbon–carbon bond lengths appear to vary very little in size with increasing number of carbon atoms, in agreement with experiment. But variations in resonance energy are significant, and indicate clearly that resonance, by itself, favours an approximately square, rather than oblong, shape. But in the case of such layers in equilibrium in the presence of molecular hydrogen, the most stable layer containing a given number of carbon atoms is of the long, thin polyphenyl type. Some tentative calculations suggest that polymerisation of smaller groups to larger ones should be endothermic, in agreement with the experimental fact that the formation of larger graphitic crystallites during carbonisation occurs, with emission of hydrogen, only at high temperatures.
III.—The Simplest Form of Second-Order Linear Differential Equation, with Periodic Coefficient, having Finite Singularities
Authors: Cambi Enzo 
Published: July 2016

SynopsisA differential equation of the second order, arising in problems of disturbed oscillation, such as occur in frequency modulation, is considered. The nature of its solutions is examined by the method of continued fractions. The cases in which the solutions are periodic, and the regions of stability and instability (lability), are determined according to the values taken by the two parameters involved.
IX.—A Measurement of the Velocity of Light
Authors: Houstoun R. A. 
Published: July 2016

SynopsisThe author has already described a new method of measuring the velocity of light, which replaces Fizeau's toothed wheel by a piezo-quartz. This acts as an intermittent diffraction grating, and it interrupts the beam 200 times more rapidly than Fizeau's wheel did.The present paper describes the application of the method to the measurement of the velocity of light in air. The total length of path was 78 metres. The frequency of interruption was measured by comparison with the Droitwich radio station. The result reduced to vacuum is 299,775 kilometres per second and is in agreement with other recent determinations, but, as a result of the experience gained, it will be possible to increase the accuracy at least ten times.
XII.—Clebsch-Aronhold Symbols and the Theory of Symmetric Functions
Authors: Turnbull H. W. , Wallace A. H. 
Published: July 2016

SynopsisA square matrix A = (aij) is expressed symbolically in terms of Clebsch-Aronhold equivalent symbols aij = aiaj = βibj = …, and the symbolic expressions for symmetric functions of the latent roots of A are considered, the relation between these functions and projective invariants of the bilinear form uAx being noted. The Newton and Brioschi relations between the symmetric functions are obtained by reduction of symbolic determinants and permanents respectively, and the Wronskian relations are shown to be equivalent to certain identities between determinants and permanents due to Muir. Also the fundamental theorem of symmetric functions is obtained symbolically as a consequence of the first fundamental theorem of invariants. The paper concludes with a note on the symbolization of the h-bialternants, that is of the traces of irreducible invariant matrices of A.
VI.—On Solvability of Some Two-Parameter Eigenvalue Problems in Hilbert Space
Authors: Bohte Z. 
Published: July 2016

SynopsisThis paper studies two particular cases of the general 2-parameter eigenvalue problem namelywhere A, B, B1, B2, C, C1, C2 are self-adjoint operators in Hilbert space, all except A being bounded. The disposable parameters λ and μ have to be determined so that the equations have non-trivial solutions x, y.On the assumption that the solution is known for ∊ = o, solutions are constructed in the form of series for λ, μ, x, y as power series in ∊ with finite radius of convergence.
XIII.—The Spectrum of a Fourth-Order Differential Operator
Authors: Chaudhuri Jyoti , Everitt W. N. 
Published: July 2016

SynopsisThis paper considers the properties of the spectrum of a differential operator derived from differential expressions of the fourth order. With certain conditions on the coefficients of the differential expression the spectrum of the operator is discrete and an estimate is obtained of the number of eigenvalues lying in a given bounded interval of the real line. The results are compared with those obtained by alternative methods. Additional restrictions on the coefficients give special cases previously considered by other authors.
XV.—Separation of the light particle in the “ternary” fission process
Authors: Feather N. 
Published: July 2016

SynopsisIt is shown that the essential condition, energy-wise, for the emission of a light particle from a binary fission fragment, in the immediate post-scission stage, is that the fragment deformation must be capable of sudden partial collapse so as to release energy equal to the binding energy of the particle in the undeformed (unexcited) fragment together with an amount cancelling the mutual (electrostatic) potential energy of the particle and the residual deformed (excited) fragment at the instant of separation. On this basis the mean energy required for alpha-particle release in the thermal-neutron-induced ternary fission of 235U is estimated as 16·5 MeV, and it is concluded that those binary fissions which develop into alpha-particle-accompanied ternary fissions in this case are those in which, on the average, the total deformation-excitation energy of the fragments is some 10 MeV greater than the most probable value for all binary fissions. A qualitative discussion of the relative yields of other light-particle-accompanied modes is also given.An Appendix contains a summary of comparable calculations based on the one-stage view of the ternary fission process.
I.—A class of symmetric polynomials with a parameter
Authors: Jack Henry 
Published: July 2016

SynopsisIn an attempt to evaluate the integral (5) below, using a decomposition of an orthogonal matrix (Jack 1968), the author is led to define a set of polynomials, one for each partition of an integer k, which are invariant under the orthogonal group and which depend on a real parameter α. An explicit representation of these polynomials is given in an operational form. When α = − 1, these polynomials coincide with the augmented monomial symmetric functions. When α = 1, a systematic way of taking linear combinations of these polynomials is explained and it is shown that the resulting polynomials coincide with the Schur functions from the representation theory of the symmetric group. A similar procedure in the case α = 2 then appears to give the zonal polynomials as defined by James (1964, p. 478).
VIII.—The Schrödinger Equation with a Periodic Potential
Authors: Eastham M. S. P. 
Published: July 2016

SynopsisThe differential equationin N dimensions is considered, where q(x) is periodic. When N = 1, it is known that the conditional stability set coincides with the spectrum and that these also coincide with two other sets involving eigenvalues of associated eigenvalue problems. These results have been proved by means of the Floquet theory and the discriminant. Here an alternative proof is given which avoids the Floquet theory and which applies to the general case of N dimensions.
XVI.—Creeping Waves in an Inhomogeneous Medium
Authors: Boyd W. G. C. 
Published: July 2016

SynopsisThis paper is concerned with high-frequency scattering in a medium, the square of whose refractive index varies linearly with height from a plane boundary. Two asymptotic methods are examined, namely the method of stationary phase and evaluation by residue series. The first of these corresponds to geometric optics and gives the high-frequency field in the illuminated region, while the second complements the first in the sense that if thsre is no point of stationary phase, the residue series is an asymptotic expansion of the field. The Airy functions in the residue series can be replaced by their asymptotic developments in terms of exponentials, and when this is done only the first term or first creeping wave is of genuine significance.
XVII.—Interaction of Toluenesulphinic Acid, Aldehydes and Secondary Amines
Authors: Hayes B. T. , Stevens T. S. 
Published: July 2016

Synopsisp-Toluenesulphinic acid, with formaldehyde or an aromatic aldehyde, attack the nucleus of a secondary aromatic amine, giving a 4-alkylamino-benzyl (or -benzhydryl) p-tolyl sulphone.
XX.—A Coördinatisation of Lattices by One-sided Baer Assemblies
Authors: Blyth T. S. , Hardy W. C. 
Published: July 2016

SynopsisIn an earlier publication [1] we introduced the notion of a Baer assembly and applied it to obtain a coördinatisation theory for semilattices. This was achieved by considering the semigroup of quasi-residuated (i.e. ℴ-preserving and isotone) mappings on a bounded semilattice. In the present paper we consider the semigroup of quasi-residuated ∪-homomorphisms (or hemimorphisms) on a bounded lattice and thus show how a particular type of one-sided Baer assembly can be used to provide a coördinatisation theory for lattices; and in particular for complemented, modular and distributive lattices.
18.—A Kinetic Approach to the Irreversible Thermodynamics of Membrane Transport
Authors: Hogg J. , Williams E. J. 
Published: July 2016

SynopsisThe problem of the simultaneous transport of solute and water through a cell membrane is examined from a kinetic standpoint. It is shown that the results obtained by this approach are in accord with those obtained conventionally by irreversible thermodynamics. Stress is laid on the fact that the kinetic theory has certain advantages over the conventional approach in that it provides, among other things, a form of membrane model and at the same time its range of validity is indicated.
28.—Comments on Ternary Fission: Post-scission α-Particle Emission
Authors: Vass D. G. 
Published: July 2016

SynopsisThe possibility of α-particle emission from fully accelerated fission fragments is considered. The results of trajectory calculations for such α-particles emitted during the fission of 252Cf are presented, and their significance in relation to the observed energy and angular distributions of the α-particles is discussed.
1.—On Measurable Selections
Authors: Robertson A. P. 
Published: July 2016

SynopsisMeasurable selection theorems are proved, for a compact-valued measurable multifunction into a Hausdorff space that is the continuous image of a separable metric space, and for a closed-valued measurable multifunction from a suitable measure space to a regular Souslin space. The connection between Polish spaces and certain subsets of the real line is related to a measurable selection theorem for multifunctions into a Polish space.
20.—On the Limit-point and Limit-circle Theory of Second-order Differential Equations
Authors: Ong K. S. 
Published: July 2016

SynopsisIn this paper the Weyl limit-point and limit-circle theory of second-order differential equations is extended to the case that the weight function is allowed to take on both positive and negative values—the polar case. This extension is achieved using Weyl's limit circle method.
30.—Acoustic Diffraction by an Absorbing Semi-infinite Half Plane in a Moving Fluid
Authors: Rawlins A. D. 
Published: July 2016

SynopsisThe diffraction of a line source of sound by an absorbing semi-infinite half plane in the presence of a fluid flow is examined. It is found that the radiated sound intensity, in the half space in which the source is located, can be considerably reduced by a suitable choice of the absorption parameter. For subsonic flow the system exhibits no acoustic instabilities.
18.—Singular Linear Differential Operators with many Parameters
Authors: Sleeman B. D. 
Published: July 2016

SynopsisIt is the purpose of this paper to make a study of the solutions of the following k-formally self-adjoint differential equationswhere ar, br), r = 1, 2, …, k, denote k semi-open intervals in which ar is finite and br is arbitrary and the λs, s = 1, 2, …, k, are spectral parameters.The main theme of the paper is that of extending the Hermann Weyl limit-point, limit-circle theory to the multi-parameter case. That is we consider under which circumstances there exist, for each r, one or two solutions yr(xr) of (*) which are square integrable in a suitably defined Hilbert space Hr. This is then generalised to consider the problem of investigating the possibility of the productof solutions of (*) being square integrable in H, the tensor product of the separate spaces Hr. The analyticky of the corresponding generalised Hermann Weyl coefficients mr(λ1, λ2,…, λk), r = 1,…, k, is also investigated. Some examples illustrating the theory are given and an alternative formulation of the problem is suggested.
28.—Simultaneous Emission of two Light Charged Particles in Fission
Authors: Feather N. 
Published: July 2016

SynopsisThe suggestion is made that in certain cases the light particles emitted in ternary fission may be released otherwise than in the ground state—and, in particular, that low-lying particle-unstable states may be involved. This suggestion is examined quantitatively in respect of the release of 8Be in the first excited short-lived state of 2·9 MeV excitation, and is shown to provide a satisfactory interpretation of the observation of quaternary fission in the α,α mode recently reported by Kataria et al. (1973). It appears probable that the other modes of quaternary fission observed by these authors should be similarly interpreted.
30.—The Chord Locus of a Certain Curve in [n]
Authors: Edge W. L. 
Published: July 2016

SynopsisThe sharing of a common self-polar simplex by n−1 quadrics in [n] confers special features on their curve of intersection Γn. The three-dimensional locus Mn of chords of Γn. has certain singularities, some of which are described. In conclusion, a few comments refer to the case n = 4 when Mn is defined by a single equation.