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991.
Given a subgroup G of the symmetric group S
n
on n letters, a semigroup S of transformations of X
n
is G-normal if G
S
=G, where G
S
consists of all permutations h∈S
n
such that h
−1
fh∈S for all f∈S. A semigroup S is G-normax if it is a maximal semigroup in the set of all G-normal semigroups.
In 1996, I. Levi showed that the alternating group A
n
can not serve as the group G
S
for any semigroup of total transformations of X
n
. In 2000 and 2001, I. Levi, D.B. McAlister and R.B. McFadden described all A
n
-normal semigroups of partial transformations of X
n
. Also, in 1994, I. Levi and R.B. McFadden described all S
n
-normal semigroups.
In this paper, we show that the dihedral group D
n
may serve as the group G
S
for semigroups of transformations of X
n
. We characterize a large class of D
n
-normax semigroups and describe certain D
n
-normal semigroups. 相似文献
992.
M. Teresa Duarte M. Ftima M. Piedade M. Paula Robalo C. Jacob M. Helena Garcia 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(11):m531-m534
The title compound, [1,2‐bis(diphenylphosphino)ethane](η5‐cyclopentadienyl)(4‐nitrobenzonitrile)iron(II) iodide, [Fe(η5‐C5H5)(C7H4N2O2)(C26H4P2)]I, crystallizes in the non‐centrosymmetric space group Cc, which is a promising result for obtaining quadratic non‐linear optical properties. However, the packing shows that the iodide counter‐ion promotes the cancellation of almost all the dipoles, resulting in a supramolecular motif of cationic chains aligned in opposite directions making an angle of 35.2°. The use of PF6− as counter‐ion induces the crystallization of the complex in a centrosymmetric space group. These results show that the introduction of different counter‐ions, of different size and geometry, allows specific and directional intermolecular interactions that can determine the formation of a particular type of crystal packing. 相似文献
993.
André F Lavorante Maria Fernanda Giné Ana Paula G Gervasio Carlos E S Miranda Marli F Fiore Cláudia M Bellato Emanuel Carrilho 《Analytical sciences》2003,19(12):1611-1616
A home-made system hyphenating capillary electrophoresis with an inductively coupled plasma mass spectrometer (CE-ICP-MS) for cadmium speciation of protein-binding and free cadmium ions in solution is presented. The CE-ICP-MS interface consisted of an acrylic block with an internal volume ca. 20 microL in which a platinum electrode, a capillary column, and a connection to an ICP nebulizer were inserted. A make-up electrolyte solution containing 50 mmol L(-1) Tris-HCl buffer solution (pH 9.0) was continuously flowed through the interface to the ICP nebulizer. The separation of free Cd ions, Cd-cysteine, and Cd bounded to metallothionein (MT) isoforms from rabbit liver was carried out by capillary electrophoresis, and the analytes were detected by ICP-MS. The feasibility to isolate metallothionein compounds extracted from the cyanobacterium Synechococcus PCC7942 was demonstrated. The Cd binding proteins were induced in Synechococcus PCC7942 and further analyzed by CE ICP-MS. 相似文献
994.
Gilberto A. Paula 《Statistics & probability letters》1996,30(4):333-338
Approximations for the level probabilities in testing order-restricted hypotheses are examined in this paper for generalized linear models with common slope. It is showed, in particular, that the asymptotic null distribution of the likelihood ratio statistic is a mixture of chi-squared distributions for the cases of simple order and simple tree order. Under a balanced structure, the asymptotic null distribution reduces to the well-known chi-bar-squared distribution. The use of the equal-weights level probabilities is also investigated. This approximation seems to be satisfactory when the sample sizes and the levels of the covariate are not too different among the strata. 相似文献
995.
In the sequel of the work reported in Liu et al. (1999), in which a method based on a dual parametrization is used to solve
linear-quadratic semi-infinite programming (SIP) problems, a sequential quadratic programming technique is proposed to solve
nonlinear SIP problems. A merit function to measure progress toward the solution and a procedure to compute the penalty parameter
are also proposed. 相似文献
996.
997.
G.L.S. Paula W. Figueiredo 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(4):519-522
The stationary states of the random-field Ising model are determined through the master equation approach, where the contact
with the heat bath is simulated by the Glauber stochastic dynamics. The phase diagram of the model is constructed from the
stationary values of the magnetization as a function of temperature and field amplitude. The continuous phase transitions
coincide with the equilibrium ones, while the first-order transitions occur at fields larger than the corresponding values
at equilibrium. The difference between the fields at the limit of stability of the ordered phase and that of the equilibrium
is maximum at zero temperature and vanishes at the tricritical point. We also find the mean field time auto-correlation function
at the stationary states of the model.
Received: 4 June 1997 / Revised: 5 August 1997 / Accepted: 10 November 1997 相似文献
998.
Eric Verploegen Derrick Boone Jr. Paula T. Hammond 《Journal of polymer science. Part A, Polymer chemistry》2007,45(24):3263-3266
The self-assembly behavior of siloxane based side chain liquid crystalline block copolymer thin films are investigated via grazing incidence small angle X-ray scattering and atomic force microscopy. The as-spun films displayed polystyrene cylinders perpendicular to the substrate and the cylinders reoriented parallel to the surface after thermal annealing. The morphology observed in the as-spun films is resultant from the orientation of the smectic LC mesophase relative to the substrate. Annealing above both the polystyrene glass transition temperature and the smectic to isotropic transition temperature eliminates the influence of the LC phase, leading to a reorientation of the morphology that minimizes the interfacial energy of the system. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3263–3266, 2007 相似文献
999.
Cid Andre Fidelis de Paula Gomes Yasmin El-Hage Ana Paula Amaral Carolina Marciela Herpich Fabiano Politti Sandra Kalil-Bussadori Tabajara de Oliveira Gonzalez Daniela Aparecida Biasotto-Gonzalez 《Physical Therapy Research》2015,18(1):1-6
Purpose: The aim of the present study was to investigate the effects of massage therapy on the masticatory muscles and occlusal splint usage on quality of life and pain in individuals with sleep bruxism. Method: A randomized, controlled, blinded, clinical trial was conducted involving 78 volunteers aged 18 to 40 years with sleep bruxism. Quality of life and pain assessments were performed. Results: Significant differences (p < 0.05) were found on the physical functioning, general health state, vitality, role emotional and mental health subscales. A large effect size was found for all treatment protocols with regard to pain. The largest effect was found in the combined treatment group. Conclusions: The findings of the present study reveal that the occlusal splint usage alone led to improvements in components of quality of life among individuals with sleep bruxism. Moreover, both treatments (occlusal splint usage and massage therapy on the masticatory muscles) led to a reduction in pain. 相似文献
1000.
Relaxation has been investigated in immiscible blends that consist of slightly viscoelastic components. Both the shear and normal stresses have been measured after cessation of steady shear flow as well as after transient shear histories. The latter can generate a fibrillar structure which can relax by either retraction or break-up via end-pinching or Rayleigh instabilities. Each of these three relaxation mechanisms is reflected in the shape of the stress curves, from which also the corresponding structural time scales can be deduced. The experimental results have been used to evaluate the Doi-Ohta and Lee-Park models for immiscible blends. The scaling relations by Doi-Ohta are confirmed by the experimental results, but none of the existing models can correctly predict the complex relaxation behaviour observed for a highly deformed droplet phase. In the present study an alternative approach has been proposed. The stress relaxation due to fibril break-up via Rayleigh instabilities has been predicted successfully by combining physical models for the structural changes with the basic approach of the Doi-Ohta model. 相似文献