29 research outputs found
Lotka' s Law, Co-authorship and Interdisciplinary Publishing
No full textThe robustness or breakdown of Lotka's law about the frequency distribution of scientific productivity depends on scientific cooperation, counting methods, interdisciplinary publishing and selection methods for sample collections. We have chosen to analyse the relationship using Mandelbrot's equivalent distribution model because this model is sensitive and uses the original data (scores). Five sets of authors and publications, the two sets used by Lotka, a set from High Energy Physics, a set from Microbiology and a set based on applicants to a research programme promoting young researchers have been used. It is shown that even for a sample of authors in High-Energy Physics with extremely strong co-authorship, Mandelbrot's distribution law is robust when complete-normalized (fractional) counting is used whereas complete counting results in a breakdown. In the field of Microbiology with much weaker cooperation, both counting methods result in a breakdown of Mandelbrot's law. Today a field like Microbiology with the corresponding set of journals, probably has a large content of interdisciplinary publishing and therefore no more fulfills the precondition of Lotka's law, that the total production of the authors (sources) is considered. For a set of applicants for the Emmy Noether Programme of the German Research Foundation. Mandelbrot's law breaks down despite the fact that all publications co-authored by the applicants are taken into account. In agreement with Bayes' theorem of conditional probabilities these results lead to the conjecture that any selection process of authors and/or publications causes a breakdown of Mandelbrot's law and, as a consequence Lotka's law
Noether symmetry in Horndeski Lagrangian
No full textThe Noether symmetry issue for Horndeski Lagrangian has been studied. We have been proven a series of theorems about
the form of Noether conserved charge (current) for irregular (not quadratic) dynamical systems. Special attentions have been
made on Horndeski Lagrangian. We have been proven that for Horndeski Lagrangian always is possible to find a way to make
symmetrization.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
Brill-Noether-type theorems with a movable ramification point
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 79-81).The classical Brill-Noether theorems count the dimension of the family of maps from a general curve of genus g to non-degenerate curves of degree d in projective space Pr. These theorems can be extended to include ramification conditions at fixed general points. This thesis deals with the problem of imposing a ramification condition at an unspecified point. We solve the problem completely in dimension 1, prove a closed-form existence criterion and a finiteness result in dimension 2, and provide an existence test and bound the dimension of the family in the general case.by Rebecca C. Lehman.Ph.D
Use of band-fitted Raman spectra for the physical characterization of polymers and measurement of the oriented amorphous phase
No full textRaman microprobe spectra of a spin-oriented and drawn PET filament
No full textMicroprobe Raman spectra of an amorphous spin-oriented filament (1500 m/min TUS) and its room-temperature drawn derivative (D.R.=2, 5:1) are presented. Their conformational features in the glycol and carbonyl band regions are compared with DTA and x-ray diffraction data. It is apparent that the three methods of measurement record different aspects of the morphology of these filaments
On the Hodge conjecture for quasi-smooth intersections in toric varieties
No full textWe establish the Hodge conjecture for some subvarieties of a class of toric varieties. First we study quasi-smooth intersections in a projective simplicial toric variety, which is a suitable notion to generalize smooth complete intersection subvarieties in the toric environment, and in particular quasi-smooth hypersurfaces. We show that under appropriate conditions, the Hodge conjecture holds for a very general quasi-smooth intersection subvariety, generalizing the work on quasi-smooth hypersurfaces of the first author and Grassi in Bruzzo and Grassi (Commun Anal Geom 28: 1773–1786, 2020). We also show that the Hodge Conjecture holds asymptotically for suitable quasi-smooth hypersurface in the Noether–Lefschetz locus, where “asymptotically” means that the degree of the hypersurface is big enough, under the assumption that the ambient variety PΣ2k+1 has Picard group Z. This extends to a class of toric varieties Otwinowska’s result in Otwinowska (J Alg Geom 12: 307–320, 2003)
Baryon fields with UL(3) X UR(3) chiral symmetry: Axial currents of nucleons and hyperons
No full textWe use the conventional F and D octet and decimet generator matrices to reformulate chiral properties of local (nonderivative) and one-derivative nonlocal fields of baryons consisting of three quarks with flavor SU(3) symmetry that were expressed in SU(3) tensor form by Chen et al. [Phys. Rev. D 78, 054021 (2008)]. We show explicitly the chiral transformations of the [(6, 3) circle plus (3, 6)] chiral multiplet in the "SU(3) particle basis,'' for the first time to our knowledge, as well as those of the (3, (3) over bar) circle plus ((3) over bar, 3), (8, 1) circle plus (1, 8) multiplets, which have been recorded before by Bardeen and Lee [ Phys. Rev. 177, 2389 (1969)] and Lee [Phys. Rev. 170, 1359 (1968)]. We derive the vector and axial-vector Noether currents, and show explicitly that their zeroth (chargelike) components close the SU(L) X SU(R) (3) chiral algebra. We use these results to study the effects of mixing of (three-quark) chiral multiplets on the axial current matrix elements of hyperons and nucleons. We show, in particular, that there is a strong correlation, indeed a definite relation between the flavor-singlet (i.e. the zeroth), the isovector (the third), and the eighth flavor component of the axial current, which is in decent agreement with the measured ones.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)10ARTICLE5null8
Extending the double ramification cycle using Jacobians
No full textWe prove that the extension of the double ramification cycle defined by the first-named author (using modifications of the stack of stable curves) coincides with one of those defined by the last-two named authors (using an extended Brill–Noether locus on a suitable compactified universal Jacobians). In particular, in the untwisted case we deduce that both of these extensions coincide with that constructed by Li and Graber–Vakil using a virtual fundamental class on a space of rubber maps
Reactivity studies on [Cp ` Fe(mu-I)](2): nitrido-, sulfido- and diselenide iron complexes derived from pseudohalide activation
No full textbibtex: ISI:000400553000098 bibtex\location:'THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND',publisher:'ROYAL SOC CHEMISTRY',type:'Article',affiliation:'Walter, MD (Reprint Author), Tech Univ Carolo Wilhelmina Braunschweig, Inst Anorgan & Analyt Chem, Hagenring 30, D-38106 Braunschweig, Germany. Maron, L (Reprint Author), Univ Toulouse, INSA UPS LPCNO, CNRS LPCNO, 135 Ave Rangueil, F-31077 Toulouse, France. Reiners, Matthias; Maekawa, Miyuki; Daniliuc, Constantin G.; Freytag, Matthias; Jones, Peter G.; Walter, Marc D., Tech Univ Carolo Wilhelmina Braunschweig, Inst Anorgan & Analyt Chem, Hagenring 30, D-38106 Braunschweig, Germany. White, Peter S., Univ N Carolina, Dept Chem, CB 3290, Chapel Hill, NC 27599 USA. Hohenberger, Johannes; Sutter, Joerg; Meyer, Karsten, Univ Erlangen Nurnberg, Dept Chem & Pharm, Inorgan Chem, Egerlandstr 1, D-91058 Erlangen, Germany. Maron, Laurent, Univ Toulouse, INSA UPS LPCNO, CNRS LPCNO, 135 Ave Rangueil, F-31077 Toulouse, France.','author-email':'[email protected] [email protected]',da:'2018-12-05','doc-delivery-number':'ET8MH',eissn:'2041-6539','funding-acknowledgement':'Alexander von Humboldt Foundation; NSF [CHE-0615704]; Emmy Noether and Heisenberg program [WA 2513/2, WA 2513/6]; Humboldt Foundation','funding-text':'We thank the Alexander von Humboldt Foundation for a Feodor-Lynen Fellowship (M. D. W.) and Prof. Maurice Brookhart for providing financial support (through NSF Grant CHE-0615704) and laboratory facilities (M. D. W.) during the initial phase of this research program. Deutsche Forschungsgemeinschaft (DFG) is acknowledged for generous funding by the Emmy Noether and Heisenberg program (WA 2513/2 and WA 2513/6, respectively). LM is grateful to the Humboldt Foundation for a grant of experienced researcher and the Chinese Academy of Science. CalMip is also gratefully acknowledged for a generous computational grant.','journal-iso':'Chem. Sci.','keywords-plus':'FE2O2 DIAMOND CORE; STRUCTURAL-CHARACTERIZATION; DINITROGEN ACTIVATION; SULFUR CLUSTERS; SOLVENT PURIFICATION; MOLECULAR-STRUCTURES; ELECTRON-TRANSFER; 2FE-2S CLUSTERS; DOUBLE-BOND; FE-IVN','number-of-cited-references':'106',oa:'DOAJ Gold','orcid-numbers':'Meyer, Karsten/0000-0002-7844-2998 Daniliuc, Constantin G./0000-0002-6709-3673','research-areas':'Chemistry','researcherid-numbers':'Meyer, Karsten/G-2570-2012 Walter, Marc/E-4479-2012','times-cited':'4','unique-id':'ISI:000400553000098','usage-count-last-180-days':'4','usage-count-since-2013':'20','web-of-science-categories':'Chemistry, Multidisciplinary'\International audienceThe iron half-sandwich [Cp'Fe(mu-I)](2) (Cp' = 1,2,4-(Me3C)(3)C5H2, 1) reacts with the pseudohalides NCO-, SCN-, SeCN- and N-3(-) to give [Cp'Fe(mu-NCO)](2) (2), [Cp'Fe(mu-S)](2) (3), [Cp'Fe(mu-Se-2)](2) (4) and [Cp'Fe(mu-N)](2) (5), respectively. Various spectroscopic techniques including X-ray diffraction, solid-state magnetic susceptibility studies and Fe-57 Mossbauer spectroscopy were employed in the characterization of these species. Mossbauer spectroscopy shows a decreasing isomer shift with increasing formal oxidation state, ranging from Fe(II) to Fe(IV), in complexes 1 to 5. The sulfido-bridged dimer 3 exhibits strong antiferromagnetic coupling between the Fe(III) centers. This leads to temperature-independent paramagnetism (TIP) at low temperature, from which the energy gap between the ground and the excited state can be estimated to be 2J = ca. 700 cm(-1). The iron(IV) nitrido complex [Cp'Fe(mu-N)](2) (5) shows no reactivity towards H-2 (10 atm), but undergoes clean reactions with CO (5 bar) and XylNC (Xyl = 2,6-Me2C6H3) to form the diamagnetic isocyanate and carbodiimide complexes [Cp'Fe(CO)(2)(NCO)] (7) and [Cp'Fe(CNXyl)(2)(NCNXyl)] (8), respectively. All compounds were fully characterized, and density functional theory (DFT) computations provide useful insights into their formation and the electronic structures of complexes 3 and 5
