193,883 research outputs found
Proceedings of the 3rd Workshop on Mysteries, Puzzles and Paradoxes in Quantum Mechanics - Gargnano, Italy, September 17-23, 2000 - Preface
No full textPigeon Pneumonitis, Correspondence -- 1952-61 -- Other Diseases Researched, Miscellaneous -- letter, 1952-04-29
No full textLetter from Englert, Edwin, Jr. to Sabin, Albert B. dated 1952-04-29.Sabin Collection Fair Use Policy</a
The Role of PSL(2, 7) in M‐theory: M2‐Branes, Englert Equation and the Septuples
No full textReconsidering the M2-brane solutions of (Formula presented.) supergravity with a transverse Englert flux introduced by one of us in 2016, we present a new purely group theoretical algorithm to solve Englert equation based on a specific embedding of the PSL(2, 7) group into (Formula presented.). The aforementioned embedding is singled out by the identification of PSL(2, 7) with the automorphism group of the Fano plane. Relying on the revealed intrinsic PSL(2, 7) symmetry of Englert equation and on the new algorithm we present an exhaustive classification of Englert fluxes. The residual supersymmetries of the corresponding M2-brane solutions associated with the first of the 8 classes into which we have partitioned Englert fluxes are exhaustively analyzed and we show that all residual (Formula presented.) supersymmetries with (Formula presented.) are available. Our constructions correspond to a particular case in the category of M2-brane solutions with transverse self-dual fluxes
Generalized reordering buffer management
No full textAn instance of the generalized reordering buffer management problem consists of a service station that has k servers, each configured with a color, and a buffer of size b. The station needs to serve an online stream of colored items. Whenever an item arrives, it is stored in the buffer. At any point in time, a currently pending item can be served by switching a server to its color. The objective is to serve all items in a way that minimizes the number of servers color switches. This problem generalizes two well-studied online problems: the paging problem, which is the special case when b=1, and the reordering buffer problem, which is the special case when k=1. In this paper, we develop a randomized online algorithm that obtains a competitive ratio of O(sqrt(b).ln(k)). Note that this result beats the easy deterministic lower bound of k whenever b < k^(2-e). We complement our randomized approach by presenting a deterministic algorithm that attains a competitive ratio of O(min{k^2.ln(b),k.b}). We further demonstrate that if our deterministic algorithm can employ k/(1-d) servers where d is in (0,1), then it achieves a competitive ratio of O(min{ln(b/d^2),b/d}) against an optimal offline adversary that employs k servers
Special issue: Mysteries, puzzles and paradoxes in quantum mechanics V
No full textJournal of Modern Optics516-7783-JMOP
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Redox reactions of low-valent Group 4 organometallics with 9,10-phenanthrenequinone (PQ). Crystal and molecular structure of a 10-membered tetraoxometallacycle of bis(cyclopentadienyl)zirconium(IV)
No full textThe bis(arene) derivative of titanium(0), Ti(h6-toluene)2, reacts with 9,10-phenanthrenequinone (PQ) with release of tile arene ligands
and formation of a diamagnetic brown compound best formulated as a dinuclear titanium(IV) derivative containing both 9,10-phenanthrenesemiquinone
(PSQ) and 9,10-phenanthrenediolato (PDA) ligands. MCp2(CO) 2 (M = Zr, Hf) react with PQ to give MCp2PDA which
has been characterized by single crystal X-ray diffractometry for M = Zr. Crystal data: C48H 3604Zr2, M = 859.26 g mol-1, monoclinic,
space group P21/n (No. 14), a = 11.647(8), b = 17.07(1), c = 18.80(1),~, /3= 97.17(6) °, V= 3709(7)A 3, Z= 4, dcalc := 1.539gcm -3,
bt = 5.97 cm -~, F(000) = 1744. The structure consists of dinuclear [ZrCp2PDA] 2 units, the two ZrCp2 groups being bridged by the PDA
ligands to give a 10-membered tetraoxazirconacycle
Self-consistent assessment of Englert-Schwinger model on atomic properties
No full textOur manuscript investigates a self-consistent solution of the statistical atom model proposed by Berthold-Georg Englert and Julian Schwinger (the ES model) and benchmarks it against atomic Kohn-Sham and two orbital-free models of the Thomas-Fermi-Dirac (TFD)-λvW family. Results show that the ES model generally offers the same accuracy as the well-known TFD-15vW model; however, the ES model corrects the failure in the Pauli potential near-nucleus region. We also point to the inability of describing low-Z atoms as the foremost concern in improving the present model.Peer reviewe
The tetracyclopentadienyls of titanium, zirconium and hafnium: new synthetic procedures and reactivity
No full textIn toluene as medium, the tetra(cyclopentadienyl) derivatives of Group 4 elements, MCp4 (MTi, Zr, Hf), have been prepared
in high yields from MCp2Cl2 and NaCp. The reactivity of ZrCp4 with species containing active protons such as Ph3SiOH or strong
acids has been studied. Substituted bis(cyclopentadienyl) derivatives were produced except in the case of the reaction between
ZrCp4 and CF3SO3H. In this case, the tris(cyclopentadienyl) derivative ZrCp3(CF3SO3) was obtained as a pale yellow crystalline
material, reactive with water to give the m-oxo derivative of zirconium(IV), [ZrCp2(CF3SO3)]2O, which has been characterized by
standard methods and by X-ray diffraction. Crystal data: C22H20F6O7S2Zr2, M756.96 g mol1, monoclinic, space group C2:c
(no. 15), a19.525(4), b9.028(2), c16.152(5) A°
, b107.31(2)°, V2718.2(1) A°
3, Z4, dcalc1.850 g cm3, l(Cu–Ka)
1.54184 A°
, T291 K, m85.66 cm1, F(000)1496, R0.054, Rw0.049
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