847 research outputs found
Quantum shape effects on Zeeman splittings in semiconductor nanostructures
We develop a general method to calculate Zeeman splittings of electrons and
holes in semiconductor nanostructures within the tight-binding framework. The
calculation is carried out in the electron-hole picture and is extensible to
the excitonic calculation by including the electron-hole Coulomb interaction.
The method is suitable for the investigation of quantum shape effects and the
anisotropy of the g-factors. Numerical results for CdSe and CdTe nanostructures
are presented
Cholangiographic Features in the Diagnosis and Management of Obstructive Icteric Type Hepatocellular Carcinoma
In 11 years and 3 months, 2037 patients with HCC
were seen and 48 patients (2.4%) were diagnosed to
have obstructive icteric type HCC. Five patients
were terminally ill and were not investigated further.
Forty three patients were initially investigated
by endoscopic retrograde cholangiography (ERC) or
percutaneous transhepatic cholangiogram (PTC) and
classified as having obstructive icteric type 1, 2, or 3
HCC based on the cholangiographic findings. The
obstruction in type 1 HCC was due to intraluminal
tumour casts and/or tumour fragments obstructing
the hepatic ductal confluence or common bile duct,
while intraluminal blood clots, from haemobilia,
filling the biliary tree was the cause in type 2 HCC.
The pathology in type 3 HCC was extraluminal
obstruction by extensive tumour encasement of the
intra–hepatic biliary ductal system and/or extrinsic
compression of the hepatic and common bile ducts
by tumour(s) and/or malignant lymph nodes. At
the initial ERC/PTC, 10 patients (5 resected, 50%)
had obstructive icteric type 1 and 23 patients (0 resected)
had obstructive icteric type 3 HCC. Of the 10
patients initially classified according to cholangiography
to have obstructive icteric type 2 HCC,
subsequent investigations revealed that 6 patients
had type 1 HCC (4 resectable, 67%) and 4 patients
had type 3 HCC (0 resectable). The classification of
the obstructive icteric type HCC into types 1, 2, and
3, based on the initial cholangiographic appearances
has simplified and rationalized our management
strategy for this condition
Long-term evaluation of cantilevered versus fixed–fixed resin-bonded fixed partial dentures for missing maxillary incisors
© 2016 Elsevier LtdObjectives To evaluate the long-term longevity and patient-reported outcomes of two-unit cantilevered (CL2) and three-unit fixed–fixed (FF3) resin-bonded fixed partial dentures (RBFPDs) for the replacement of a maxillary permanent incisor. Materials and methods Twenty-eight subjects were randomly assigned to receive either a CL2 or FF3 RBFPD placed by one operator. Prosthesis longevity was determined by clinical examination and history. Success was defined as absence of complications requiring intervention and survival as retention of the original prosthesis in mouth. Subjects’ satisfaction was assessed using visual analogue scale (VAS) and oral health-related quality of life (OHRQoL) using Oral Health Impact Profile (OHIP-49). Outcomes were analysed with t-test/Mann–Whitney U test, chi-square and log-rank test at significance level α = 0.05. Results Twenty-two subjects were reviewed. Thirteen of fifteen CL2 and ten of fourteen FF3 RBFPDs were examined (79.3 percent response rate) with a mean service life of 216.5 ± 20.8 months. All CL2 RBFPDs survived with no complications while only 10 percent of FF3 experienced no complications and only 50 percent of them survived (both P = 0.000). CL2 had a significantly better success and survival rate than FF3 (P = 0.000 and P = 0.009, respectively). There was no significant difference in subjects’ satisfaction and OHRQoL apart from CL2 group subjects had a higher satisfaction in cleaning of the prosthesis (84.1 ± 13.6) than FF3 group (72.6 ± 11.7) (P = 0.05). Conclusions Two-unit cantilevered RBFPDs were observed to have a significantly better success and survival than the FF3 design for the replacement of a maxillary incisor. Good patient-reported outcomes have been found for RBFPDs in single-tooth replacement in aesthetic zone.postprin
Spectroscopic properties and antimicrobial activity of dioxomolybdenum(VI) complexes with heterocyclic S,S’-ligands
Five new dioxomolybdenum(VI) complexes of the general formula[MoO2(Rdtc)2], 1-5, where Rdtc-refer to piperidine- (Pipdtc), 4-morpholine-(Morphdtc), 4-thiomorpholine-(Timdtc), piperazine- (Pzdtc) or Nmethylpiperazine- (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. Elemental analysis, conductometric measurements, electronic, IR and NMR spectroscopy have been employed to characterize them. Complexes 1-5 contain a cis-MoO2 group and are of an octahedral geometry. Two dithiocarbamato ions join as bidentates with both the sulphur atoms to the molybdenum atom. The presence of different heteroatom in the piperidinо moiety influences the v(C----N) and v(C----S) vibrations, which decrease in the order of the complexes with: Pipdtc > N-Mepipdtc > Morphdtc > Pzdtc > Timdtc ligands. On the basis of spectral data, molecular structures of complexes 1-5 were optimized on semiempirical molecular-orbital level, and the geometries, as obtained from calculations, described. Antimicrobial activity was tested against nine different laboratory control strains of bacteria and two strains of yeast Candida albicans. All tested strains were sensitive. Complexes bearing heteroatom in position 4 of piperidine moiety are significantly more potent against bacteria tested comparing to corresponding ligands
Ability of Near Infrared Spectroscopy to Monitor Air-Dry Density Distribution and Variation of Wood
Process control of wood density with near infrared spectroscopy (NIR) would be useful for pulp mills that need to maximize pulp yield without compromising paper strength properties. If models developed from the absorbance at wavelengths in the NIR region could provide density histograms, fiber supply personnel could monitor chip density variation as the chips enter the mill. The objectives of this research were to a) develop density histograms from actual density versus density histograms developed through NIR modeling, and b) determine the precision of density models developed from absorbance in the NIR region with a recommendation for the sample size needed to estimate the standard deviation of density at a given precision.Models for density were developed from calibration samples (n = 170) and then validated with 93 randomly held aside samples. The samples were systematically removed from 10 longleaf pine trees of equal age, but different growth rates. The histogram patterns for actual density almost paralleled the histogram patterns developed from predictive models. Subsequently, the validation data set was randomly categorized into groups of three, and the standard deviations of density were measured. For three measurements per data point, the predicted standard deviation covaried with the actual standard deviation of density with an R2 = 0.61 and 0.55 for the calibration and validation data set, respectively. A sample size of 30 was recommended to estimate the standard deviation of density with a precision of 0.01 g/cm3
The Response of Visible/Near Infrared Absorbance to Wood-Staining Fungi
The influence of blue-stain fungi [Ophiostoma minus (Hedgcock) H. and P. Sydow and Leptographium serpens (Goid.) Siemaszko] on absorbance at the visible and near infrared wavelengths was investigated. Forty trees were sampled at breast height from longleaf pine (Pinus palustris Mill.). One half of each increment core was inoculated with one of two fungi treatments while the other half served as a control. Visible and near infrared spectra were acquired between rings 3-40 for the stained and control-clear wood samples (n = 304). Absorbance was greater for the stained than the control wood at wavelengths between 464 to 1334 nm. Statistical techniques were applied to the NIR data to determine which wavelengths, and their corresponding chemical assignments, were most affected by the fungi. First and 2nd derivative pretreatments to the original spectra resulted in some blue-stain sensitive wavelengths throughout the 350 to 2500 nm range, some of which are associated with nitrogen in the melanin present in blue stain. However, for the 2nd derivative pretreatment, the stained wood exhibited a different signal to noise ratio than the control wood, and thus the pretreatment method should be used with vigilance. For the raw, 1st, and 2nd derivatives, the absorbance of L. serpens (n = 164) significantly differed from O. minus (n = 140) between 424-554 nm. The results of this study are important because the absorbance at visible and NIR wavelengths may be used to classify stained wood
Lower bounds on the complexity of simulating quantum gates
We give a simple proof of a formula for the minimal time required to simulate
a two-qubit unitary operation using a fixed two-qubit Hamiltonian together with
fast local unitaries. We also note that a related lower bound holds for
arbitrary n-qubit gates.Comment: 6 page
SÃntese dos aspectos centrais da perspectiva teórica de Sidney Blatt sobre a depressão (*)
Neste artigo apresentamos os aspectos centrais da
perspectiva teórica de Sidney Blatt sobre a depressão.
Expomos alguns aspectos gerais do seu modelo, as caracterÃsticas
dos dois tipos depressivos propostos por
Blatt, algumas notas sobre o desenvolvimento das representações
objectais e sobre os antecedentes da depressão
e expomos ainda a componente de vulnerabilidade
multi-causal do modelo de Blatt. Terminamos
com algumas considerações finaisABSTRACT: In this article we present the most important aspects
of Sidney Blatt’s theoretical perspective on depression.
We present some general aspects of his model, the
characteristics of the two depression types proposed by
Blatt, some notes about the development of objectal
representations and about the depression’s antecedents
and also the multi-causal vulnerability component
of Blatt’s model. We finish with some final considerationsinfo:eu-repo/semantics/publishedVersio
Quantum dynamics as a physical resource
How useful is a quantum dynamical operation for quantum information
processing? Motivated by this question we investigate several strength measures
quantifying the resources intrinsic to a quantum operation. We develop a
general theory of such strength measures, based on axiomatic considerations
independent of state-based resources. The power of this theory is demonstrated
with applications to quantum communication complexity, quantum computational
complexity, and entanglement generation by unitary operations.Comment: 19 pages, shortened by 3 pages, mainly cosmetic change
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