550 research outputs found
Sign learning kink-based (SiLK) quantum Monte Carlo for molecular systems
The Sign Learning Kink (SiLK) based Quantum Monte Carlo (QMC) method is used
to calculate the ab initio ground state energies for multiple geometries of the
HO, N, and F molecules. The method is based on Feynman's path
integral formulation of quantum mechanics and has two stages. The first stage
is called the learning stage and reduces the well-known QMC minus sign problem
by optimizing the linear combinations of Slater determinants which are used in
the second stage, a conventional QMC simulation. The method is tested using
different vector spaces and compared to the results of other quantum chemical
methods and to exact diagonalization. Our findings demonstrate that the SiLK
method is accurate and reduces or eliminates the minus sign problem.Comment: 20 pages, 9 figures, to appear in the Journal of Chemical Physic
E-cadherin expression in primary carcinomas of the breast and its distant metastases
INTRODUCTION: Aberrant expression of E-cadherin has been associated with the development of metastases in patients with breast cancer. Even though the expression of E-cadherin has been studied in primary breast tumors, little is known about its expression at the distant metastatic sites. We investigate the relationship between E-cadherin expression in primary breast carcinoma and their distant, non-nodal metastases. METHODS: Immunohistochemical analysis of E-cadherin was performed in tissues from 30 patients with primary invasive breast carcinoma and their distant metastases. E-cadherin expression was evaluated as normal or aberrant (decreased when compared with normal internal positive controls, or absent). RESULTS: Twenty-two (73%) invasive carcinomas were ductal, and eight (27%) were lobular. Of the primary invasive ductal carcinomas, 55% (12/22) had normal E-cadherin expression and 45% (10/22) had aberrant expression. All of the metastases expressed E-cadherin with the same intensity as (12 tumors) or with stronger intensity than (10 tumors) the corresponding primaries. Of the invasive lobular carcinomas, one of eight (12%) primary carcinomas and none of the metastases expressed E-cadherin in the cell membranes, but they accumulated the protein in the cytoplasm. CONCLUSION: Aberrant E-cadherin expression is frequent in invasive ductal carcinomas that progress to develop distant metastases. Distant metastases consistently express E-cadherin, often more strongly than the primary tumor. Invasive lobular carcinomas have a different pattern of E-cadherin expression, suggesting a different role for E-cadherin in this form of breast carcinoma
E-cadherin expression in primary carcinomas of the breast and its distant metastases
Abstract
Introduction
Aberrant expression of E-cadherin has been associated with the development of metastases in patients with breast cancer. Even though the expression of E-cadherin has been studied in primary breast tumors, little is known about its expression at the distant metastatic sites. We investigate the relationship between E-cadherin expression in primary breast carcinoma and their distant, non-nodal metastases.
Methods
Immunohistochemical analysis of E-cadherin was performed in tissues from 30 patients with primary invasive breast carcinoma and their distant metastases. E-cadherin expression was evaluated as normal or aberrant (decreased when compared with normal internal positive controls, or absent).
Results
Twenty-two (73%) invasive carcinomas were ductal, and eight (27%) were lobular. Of the primary invasive ductal carcinomas, 55% (12/22) had normal E-cadherin expression and 45% (10/22) had aberrant expression. All of the metastases expressed E-cadherin with the same intensity as (12 tumors) or with stronger intensity than (10 tumors) the corresponding primaries. Of the invasive lobular carcinomas, one of eight (12%) primary carcinomas and none of the metastases expressed E-cadherin in the cell membranes, but they accumulated the protein in the cytoplasm.
Conclusion
Aberrant E-cadherin expression is frequent in invasive ductal carcinomas that progress to develop distant metastases. Distant metastases consistently express E-cadherin, often more strongly than the primary tumor. Invasive lobular carcinomas have a different pattern of E-cadherin expression, suggesting a different role for E-cadherin in this form of breast carcinoma.http://deepblue.lib.umich.edu/bitstream/2027.42/112744/1/13058_2003_Article_652.pd
Poland: a successful transition to budget sustainability?
In this paper we evaluate the sustainability of the current fiscal policy regime in Poland, which
has been in place for almost 10 years since the start of the economic reform process. We use the
intertemporal budget constraint (IBC) as a framework, and evaluate the sustainability of current
policies. Consistency of fiscal policy with the IBC is evaluated using unit root and cointegration
tests. In contrast to much previous research on fiscal sustainability in western economies, we
explicitly take account of the possible role of seignorage from money creation as a source of
government revenue. Sustainability tests are conducted excluding and then including seignorage.
We find firm evidence that Polish fiscal policy is sustainable, and that the fiscal regime is
"expenditure-led", adjusting tax revenues to the planned levels of government expenditures. This
would appear to bode well for Poland's prospective entry to the EU and possible subsequent
consideration of membership of the monetary union
Equation of motion coupled cluster methods for electron attachment and ionization potential in polyacenes
Polyacenes have attracted considerable attention due to their various applications in organic optoelectronic materials. This study focuses on linear polyacenes and their electron affinity (EA) and ionization potential (IP) properties. We have employed our recent implementation of EA/IP equation of motion coupled cluster singles and doubles (EA/IP-EOMCCSD) methods which are accurate, computationally efficient and are capable of treating large systems employing reasonable basis sets size. The EA/IP results obtained for naphthalene, anthracene, tetracene, pentacene, hexacene and heptacene are in a good agreement with experiment. Comparison between quality of excitation energies obtained from IP-EOMCCSD and EE-EOMCCSD formalisms were also studied
- …