bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ueber die Blitzröhren und ihre Entstehung
Authors: Fiedler Karl Gustav 
Published: April 2007

AbstractMit wahrem Vergnügen lege ich meinen Lesern diese wohlgerathene mineralogisch‐physikalische Monographie eines Gegenstandes vor, welcher der Aufmerksamkeit der Physiker werth ist. Sie rührt von einem jungen Manne her, der den berühmten Lehrern Göttingens, welche ihn zu diesem Unternehmen ausgemuntert und es befördert haben, seinen Dank mit ihr darzubringen wünschte, und dieses auf eine desto ehrenvollere Art mir zu thun scheint, je befriedigender diese seine Arbeit ist. Dass die Blitzröhren zuerst in Deutschland, und zwar in der unter dem Namen der Senne bekannten Sandwüste Paderborns, von dem unweit derselben in dem Fürstenthum Lippe wohnenden Oekonomen, Herrn Hentzen, entdeckt, und durch ihn, als solche, im Jahr 1805 bekannt geworden sind, dürfte den mehrsten meiner Leser unbekannt seyn.
Bei einem Gewitter angeblich herabgefallner Phosphor
Authors: Gilbert  
Published: April 2007

AbstractWas Herr Chaldni S. 274. seines an neuen und erwägungswerthen Ansichten reichen Aufsatzes von Schwefel anführt, der als Meteor herabgefallen seyn soll (womit man Ritter's Gedanken in diesen Annalen B. 2. S. 3. vergleiche), veranlasst mich, diese letzte Seite mit der Erzählung eines Falls auszufüllen, wo man in dem Dorfe Connewitz bei Leipzig dasselbe von Phosphor beobachtet zu haben glaubte. Im August 1814, an einem Dienstag, um 3 Uhr Nachmittags donnerte es zwei Mal sehr heftig und plötzlich; der zweite Schlag besonders dünkte den Einwohnern über ihren Köpfen zu entstehen, und gleich nach demselben fing es an zu hageln. Der Besitzer des Landhauses, welches am Eingange des Dorfs, wenn man von Leipzig kömmt, liegt, erzählte mir am folgenden Tage, seine Bedienung habe um 10 Uhr Abends in dem kleinen Hofe, vor der Thüre der Küche, etwas, wie ein schön leuchtendes Johanniswürmchen, erblickt, und es hineingenommen. Am andern Tage hatte es an der feuchten Stelle, wo es lag, einen Fleck von der Grösse eines Kirschkerns gezogen; von der Köchin in ihrer Schürze der Herrschaft gebracht, entzündete es sich und auf Papier, das von Kohlenstaub schwarz war, brannte es mit heller Flamme und weissem Qualm. Der Besitzer hatte die Güte mir das Papier und den Körper mitzubringen, von dem seine Hausgenossen glaubten, er sey mit dem gewaltigen Donnerschlage am vorigen Nachmittage herabgefallen. Es war ein 1/3 Zoll langes Stückchen eines dünnen Phosporstängelchens mit länglichem unregelmässigen Endbruche. An einen meteorischen Ursprung konnte ich bei dieser Gestaltung nicht glauben, wohl aber an einen Muthwillen irgend eines Unvorsichtigen. Einen ähnlichen Körper, hörte ich nacher, solle der Nachtwächter vor dem Thorweg der Schenke gesehen und in den Sand getreten, auch ein kleiner vom Herrn Kaufmann Kraft verschickter Junge gefunden und eingesteckt haben, das Ding habe aber in seiner Tasche angefangen zu brennen.
Surface properties of Reverse osmosis membrane
Authors: Yongyi Yao , Shiwei Guo , Yunxiang Zhang 
Published: April 2007

AbstractThe morphology and structure of the top surfaces of three commercially Reverse osmosis (RO) membranes (Vontron Eviro‐Tech) have been studied using SEM and AFM techniques. As a result, the unevenness of the surface of ULP21 membrane was the greatest and that of SW21 membrane was smooth. The more the roughness of the top surface of the RO membranes was, the larger the flux of the RO membranes was. Accordingly, the roughness of the top surface of RO membranes intensively affected on the performance of RO membrane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Assessment of non‐response bias in a survey of residential magnetic field exposure in Taiwan
Authors: Li Chung‐Yi , Mezei Gabor , Sung Fung‐Chang , Silva Michael , Lee Pei‐Chen , Chen Pei‐Chun , Chen Li‐Mei 
Published: April 2007

AbstractWe assessed potential non‐response bias in obtaining information on residential extremely low‐frequency power frequency magnetic field (MF) in Taiwan. All households occupied by children aged less than 7 years in two study districts, one in an urban town and the other in a rural town, were visited and solicited for on‐site measurements in late 2003. The initial response rate was only 32% (33/104, urban) and 60% (61/101, rural). In the same season 1 year later, we performed a second survey of those who declined to be measured at the initial survey and successfully measured another 77 residences (50 and 27 for urban and rural districts, respectively). The two districts were selected mainly because the local public health officers were quite willing to assist the initial survey and to inform residents of the second survey. Except for meteorological conditions, the two surveys came up with very similar findings regarding residential characteristics and power facilities surrounding the houses. The mean residential MF for the urban residences was .121 and .140 micro‐Tesla (µT) (P = .620) for the two surveys. The corresponding figures for the rural residences were .119 and .115 µT (P = .802). Although limited in its scope, this study tends to indicate that measurement studies of residential MF are less likely to suffer from serious selection bias if sampling is confined within a small district where people have similar socioeconomic characteristics. Bioelectromagnetics 28:340–348, 2007. © 2007 Wiley‐Liss, Inc.
Sentinel node biopsy for breast cancer larger than 3 cm in diameter
Authors: Schüle J , Frisell J , Ingvar C , Bergkvist L 
Published: April 2007

AbstractBackgroundSentinel node biopsy (SNB) is a standard staging procedure in early breast cancer. Its suitability for larger tumours has been questioned. This study evaluated the reliability of SNB in women with invasive breast cancer larger than 3 cm in diameter who were clinically axillary node negative.MethodsSome 109 women with a tumour larger than 3 cm on pathological analysis were identified from the Swedish prospective SNB database. They were included if a completion axillary clearance was planned, regardless of SNB results.ResultsThe sentinel node detection rate was 103 (94·5 per cent) of 109. The overall false-negative rate was eight (13 per cent) of 64. Although a preoperative diagnosis of multifocal tumour was an exclusion criterion, 16 such cases were revealed on postoperative pathological examination. The false-negative rate in this subgroup was higher than that in women with a unifocal tumour (four (31 per cent) of 13 versus four (8 per cent) of 51; P = 0·012). No other significant predictors of a false-negative sentinel node biopsy were identified.ConclusionSNB is feasible in patients with unifocal breast tumours larger than 3 cm. When large tumour size coincides with multifocality, however, the false-negative rate seems to be increased and a completion axillary clearance should be considered even if the SNB is negative.
An Intermediate for the Clean Synthesis of Ionic Liquids: Isolation and Crystal Structure of 1,3‐Dimethylimidazolium Hydrogen Carbonate Monohydrate
Authors: Bridges Nicholas J. , Hines C. Corey , Smiglak Marcin , Rogers Robin D. 
Published: April 2007

Abstract1,3‐Dimethylimidazolium‐2‐carboxylate and carbonic acid have been used to prepare a 1,3‐dimethylimidazolium hydrogen carbonate salt by means of a Krapcho reaction. The ability to form hydrogen carbonate azolium salts allows for them to be used as precursors for fast, efficient, environmentally benign, and halide‐free syntheses of many ionic liquids by a simple, acid–base reaction of virtually any acid (inorganic, organic, and organic noncarboxylic) with a pKa less than that of HCO3−. Additionally, the kinetics of this reaction can be accelerated by employing catalytic amounts of DMSO (a traditional Krapcho solvent used in decarboxylation reactions) to catalyze the decarboxylation. The crystal structure of 1,3‐dimethylimidazolium hydrogen carbonate monohydrate is the first example of an imidazolium‐based hydrogen carbonate salt. There is a strong 2D hydrogen‐bonded network with facially π‐stacked imidazolium cations located in the cavities created by this framework.
Determination of the enantiomeric excess of chiral carboxylic acids by 31P NMR with phosphorylated derivatizing agents from C2‐symmetrical diamines containing the (S)‐α‐phenylethyl group
Authors: Mastranzo Virginia M. , Quintero Leticia , de Parrodi Cecilia Anaya 
Published: April 2007

AbstractThe use of P(III) and P(V) organophosphorus derivatizing agents prepared from C2 symmetrical (1R,2R)‐ and (1S,2S)‐trans‐N,N′‐bis‐[(S)‐α‐phenylethyl]‐cyclohexane‐1,2‐diamines 1 and 2, as well as (1R,2R)‐ and (1S,2S)‐trans‐N,N′‐bis‐[(S)‐α‐phenylethyl]‐4‐cyclohexene‐1,2‐diamines 3 and 4 for the determination of enantiomeric composition of chiral carboxylic acids by 31P NMR, is described. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Enantioseparation of phenylglycinol in chiral‐modified zeolite HY: A molecular simulation study
Authors: Jirapongphan Siricharn S. , Warzywoda Juliusz , Budil David E. , Sacco Albert 
Published: April 2007

AbstractA mechanism has been proposed for the separation of valinol enantiomers using a chiral‐modified zeolite HY (i.e., zeolite HY containing (+)‐(1R;2R)‐hydrobenzoin) Molecular modeling of chiral‐modified zeolite HY employed in enantioselective separation. Jirapongphan SS, Warzywoda J, Budil DE, Sacco A Jr. Chirality 2007; in press, which accurately predicted the experimentally measured enantioseparation. This methodology has been applied to predict the separation of an enantiomeric pair of phenylglycinol molecules (a precursor in the synthesis of HIV‐1 protease inhibitors) using the modified zeolite HY as a CSP. Phenylglycinol and valinol molecules are similar in terms of the presence of polar (i.e., amine and hydroxyl) groups. These functional groups are important in the proposed chiral discrimination. Supercage‐based docking simulations yielded an enantioselectivity of 1.3 with (+)‐(S)‐phenylglycinol molecule better retained in the zeolite. Also, the simulations predicted two binding modes that were the same as those in the valinol system. This suggests that specific structural features (i.e., number and type of polar groups), which generate the hypothesized binding modes, are required in an enantioseparation utilizing the chiral‐modified zeolite HY. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Generalizations of the neumann system a curve‐theoretical approach‐part I
Authors: Schilling R. J. 
Published: April 2007

AbstractThe following observation, due to E. Trubowitz, illustrates an intimate relationship between spectral theory and Hamiltonian mechanics in the presence of constraints. Let q(s) be a real periodic function such that the Hill operator, magnified image has only a finite number gR of simple eigenvalues. There exist gR + 1 periodic eigenfunctions x1,…, x and corresponding eigenvalues a1,…, a of L such that magnified image where yr = dxr/ds. The equations Lxr = arxr, r = 1,…,gR+1, make up the classical Neumann system, a system of harmonic oscillators constrained to the unit sphere.H. Flaschka obtained similar results about the Neumann system from a more general point of view. His assumption, that there exists an operator of odd order that commutes with L, leads to algebraic curve theory by the method of Krichever and from there to the Neumann formulas above. The familiar Lax pairs, the constants of motion and the quadrics of the Neumann system emerge as consequences of the Riemann‐Roch theoreni. The existence of isospectral deformations of L, the Korteweg de‐Vries hierarchy of the soliton equations, underlies the complete integrability of the Neumann system. This paper extends Flaschka's techniques, replacing L by an operator of order n 2 2. Higher Neumann systems are defined in a way that leads naturally to interesting symplectic manifolds, Lax pairs and integrals of motion. C. Tomei, using scattering theory, obtained some of our n = 3 formulas.
Frames in the bargmann space of entire functions
Authors: Daubechies Ingrid , Grossmann A. 
Published: April 2007

AbstractWe look at the decomposition of arbitrary f in L2(R) in terms of the family of functions φmn(x) = π−1/4exp{ − 1/2imnab + i max − 1/2(x − nb)2}, with a, b > 0. We derive bounds and explicit formulas for the minimal expansion coefficients in the case where ab = 2π/N, N an integer ≧ 2. Transported to the Hilbert space F of entire functions introduced by V. Bargmann, these results are expressed as inequalities of the form

We conjecture that these inequalities remain true for all a, b such that ab < 2π.
Inverse boundary value problems at the boundary—continuous dependence
Authors: Sylvester John , Uhlmann Gunther 
Published: April 2007

AbstractWe use the methods of microlocal analysis to give a new proof of a theorem of Kohn and Vogelius, showing that the boundary values of a continuous isotropic conductivity can be recovered from voltage and current measurements at the boundary. Moreover, we prove sharp estimates to establish the continuous dependence of the boundary values of the conductivity on the voltage to current maps.
BETAS, a spectral code for three‐dimensional magnetohydrodynamic equilibrium and nonlinear stability calculations
Authors: Betancourt Octavio 
Published: April 2007

AbstractA fully three‐dimensional spectral code has been developed and implemented. It computes three‐dimensional equilibria using the variational approach, by minimizing the potential energy subject to appropriate constraints. A second minimization, with an additional constraint, is used to examine the stability of solutions.The magnetic field representation allows for non‐nested flux surfaces. Thus it can be used to study solutions with islands and variation of the potential energy with respect to topology changes.A spectral representation in the toroidal and poloidal angles, coupled with a special choice of collocation points in the radial direction results in greatly enhanced resolution.A fast iterative method was developed, with the number of iterations required for convergence independent of the mesh size. Residuals converge exponentially to the round‐off error, allowing the potential energy to be computed to the eight‐digit accuracy required for nonlinear stability analysis. A small amount of artificial viscosity may be needed for convergence in cases where low‐order resonances are present in the plasma region.Numerical results show convergence to known axially symmetric equilibrium solutions, as well as close agreement with eigenvalue calculations in helically symmetric stellarator configurations. Solutions exhibiting island formations are found to have lower potential energy than that of the nearby nested case. Internal modes are found to localize inside the resonant surface, with the eigenfunction having sharp gradients at the resonant surface.
The interaction of nonlinear hyperbolic waves
Authors: Glimm James 
Published: April 2007

AbstractNonlinearities in wave equations lead to focusing and defocusing of solutions. Focusing causes sharply defined wave fronts. The interaction of such sharply defined wave fronts and more generally of nonlinear hyperbolic waves is of fundamental importance and includes such phenomena as Mach triple point formation, shock wave diffraction patterns and the study of Riemann problems in one and higher dimensions.Recent progress in the study of nonlinear hyperbolic wave interactions has revealed a surprising range of new mathematical phenomena and structures. This mathematical theory should be useful in the design of improved computational algorithms and in part was motivated by such considerations. It is also of considerable interest for its own sake as new mathematical phenomena as well as in terms of the direct insight it provides into physical phenomena.Within the subject matter and point of view adopted here, we have attempted to present a broad and, we hope, a representative account of recent progress.
Magnetic and drift surfaces in stellarators
Authors: Ng Kam‐Chuen 
Published: April 2007

AbstractIn this paper we study the structure of a stellarator field in toroidal geometry. A field line tracing code is developed to explore the structure of magnetic fields on the fine scale of the electron gyroradius pe, so as to explain anomalous electron transport. The magnetic field is modelled by a simple analytic representation with finite number of parameters, so that we can integrate the field lines to a high accuracy. In a typical Heliac field we find that (i) most of the magnetic surfaces are well behaved on the fine scale, even when there is no two‐dimensional symmetry and (ii) the width of an island, formed in the vicinity of a magnetic surface with rational rotational transform i = n/m, decays exponentially with m. Among those numerical studies, we have an example where the island width w is less than the electron gyroradius pe for m greater than 17. This demonstrates that higher‐order islands do not affect the electron transport.Our numerical results indicate that the anomalous electron transport observed in experiments may be due to the presence of an ambipolar electrostatic potential Φ. To reconfirm this proposition we compute the guiding center orbits of electrons and estimate the island widths of the drift surfaces that are swept out. We find that with a small electric potential depending on toroidal and poloidal angles, the drift surface island width w is an order of magnitude larger than that without the electric potential and decays exponentially at a slower rate. Since the drift step size is of the order of the maximum of pe and w, the electron transport, which scales like the square of the step size, is enhanced when there is an electric potential.
Ill‐posedness in three‐dimensional plastic flow
Authors: Schaeffer David G. , Pitman E. Bruce 
Published: April 2007

AbstractThis paper examines partial differential equations for frictional materials flowing via plastic yield, including the equations given by the Critical State Theory of Soil Mechanics. In particular, the material density is considered as a dependent variable. In previous work we demonstrated that two‐dimensional plastic flow may be ill posed due to an instability along two rays in Fourier transform space. In this paper, we show that in three dimensions the equations are linearly well posed provided all three strain rates are nonzero.
Orthonormal bases of compactly supported wavelets
Authors: Daubechies Ingrid 
Published: April 2007

AbstractWe construct orthonormal bases of compactly supported wavelets, with arbitrarily high regularity. The order of regularity increases linearly with the support width. We start by reviewing the concept of multiresolution analysis as well as several algorithms in vision decomposition and reconstruction. The construction then follows from a synthesis of these different approaches.
Hydrodynamics and large deviation for simple exclusion processes
Authors: Kipnis C. , Olla S. , Varadhan S. R. S. 
Published: April 2007

AbstractWe prove the hydrodynamical limit for weakly asymmetric simple exclusion processes. A large deviation property with respect to this limit is established for the symmetric case. We treat also the situation where a slow reaction (creation and annihilation of particles) is present.
Compactness methods in the theory of homogenization II: Equations in non‐divergence form
Authors: Avellaneda Marco , Lin Fang‐Hua 
Published: April 2007

AbstractWe prove C0, α, C1, α and C1, 1 a priori estimates for solutions of boundary value problems for elliptic operators with periodic coefficients of the form Σ,j=1ai j(x/ϵ)δ2/δxiδxj. The constants in these estimates are independent of the small parameter ϵ, and hence our results imply strengthened versions of the classical averaging theorems. These results generalize to a wide class of linear operators in non‐divergence form, including equations with lower‐order terms and nonuniformly oscillating coefficients, as well as to certain nonlinear problems, which we discuss in the last section.
Uniqueness failure for entropy solutions of hyperbolic systems of conservation laws
Authors: Sever Michael 
Published: April 2007

AbstractWe consider a nonlinear system of conservation laws, which is strictly hyperbolic, genuinely nonlinear in the large, equipped with a convex entropy function and global Riemann invariants. Nevertheless, for such a system for dimension five, it is shown that uniqueness of the similarity solution of a Riemann problem satisfying the entropy condition can fail.
An initial‐boundary value problem of physiological significance for equations of nerve conduction
Authors: Mascagni Michael 
Published: April 2007

AbstractA model of nerve conduction that has gained wide acceptance in the biophysical community is that for the giant axon of the squid Loligo of Hodgkin and Huxley [5]. This nonlinear parabolic partial differential equation (PDE), when considered as part of a particular initial‐boundary value problem (IBVP), models the electrical activity of an axon under conditions found both in nature and in the laboratory. This IBVP for the Hodgkin‐Huxley equations is proved to be well posed in the sense of Hadamard [3], and a priori bounds on the solution are derived.
Cuplength estimates on lagrangian intersections
Authors: Floer Andreas 
Published: April 2007

AbstractWe prove the following estimate on Lagrangian intersections: If L is a Lagrangian submanifold of P with π2(P, L) = 0 and L' is obtained from L by an exact diffeomorphism of P, then the number of elements of L ∩ L' is greater than or equal to the cuplength of P.
Stability theorem and truncation error analysis for the Glimm scheme and for a front tracking method for flows with strong discontinuities
Authors: Chern I‐Liang 
Published: April 2007

AbstractTypical nonlinear wave interaction problems involve strong waves moving through a background of weak disturbance. Previous existence theorems and error analysis for computations are usually restricted to more idealized situations such as small data or single equations. We consider here the problem of a single strong discontinuity interacting with a weak background for general hyperbolic systems of conservation laws. We obtain the stability, consistency theorems and upper bounds of the truncation errors for the Glimm scheme and for a front tracking method. The major error in the Glimm scheme is the error generated by the strong discontinuity. This error is reduced when a front tracking method is applied to follow the location of the strong discontinuity. This demonstrates an advantage of front tracking methods in one‐space dimension.
Generalized affine lie algebras and the solution of a class of flows associated with the QR eigenvalue algorithm
Authors: Deift P. A. , Li L. C. 
Published: April 2007

AbstractIn [3] the authors show that the QR algorithm to compute the eigenvalues of a matrix is the integer time evaluation of a completely integrable Hamiltonian system. Here the authors show that all the associated commuting integrals generate flows that can be solved explicitly via a factorization procedure on a suitable finite, or infinite‐dimensional, Lie algebra.
Molecular dynamics by the Backward‐Euler method
Authors: Peskin Charles S. , Schlick Tamar 
Published: April 2007

AbstractThis paper introduces a new computational method for molecular dynamics. The method combines the Backward‐Euler scheme for the solution of stiff differential equations with a Langevin‐equation approach to the establishment of thermal equilibrium. The method allows the user to choose a cutoff frequency ωc. Vibrational modes with frequencies below ωc will be fully excited (receive a mean energy of kT per mode), while modes with frequencies greater than ωc will be effectively frozen by the method. By setting ωc = kT/h, one can obtain reasonable agreement with the quantum‐mechanical energy distribution among the various modes, despite the classical character of the computation.