32 research outputs found
Accurate ab initio spin densities
We present an approach for the calculation of spin density distributions for
molecules that require very large active spaces for a qualitatively correct
description of their electronic structure. Our approach is based on the
density-matrix renormalization group (DMRG) algorithm to calculate the spin
density matrix elements as basic quantity for the spatially resolved spin
density distribution. The spin density matrix elements are directly determined
from the second-quantized elementary operators optimized by the DMRG algorithm.
As an analytic convergence criterion for the spin density distribution, we
employ our recently developed sampling-reconstruction scheme [J. Chem. Phys.
2011, 134, 224101] to build an accurate complete-active-space
configuration-interaction (CASCI) wave function from the optimized matrix
product states. The spin density matrix elements can then also be determined as
an expectation value employing the reconstructed wave function expansion.
Furthermore, the explicit reconstruction of a CASCI-type wave function provides
insights into chemically interesting features of the molecule under study such
as the distribution of - and -electrons in terms of Slater
determinants, CI coefficients, and natural orbitals. The methodology is applied
to an iron nitrosyl complex which we have identified as a challenging system
for standard approaches [J. Chem. Theory Comput. 2011, 7, 2740].Comment: 37 pages, 13 figure
Tumour microvessel density as predictor of chemotherapy response in breast cancer patients
The aim of this study was to evaluate the predictive value of intratumoural microvessel density in breast cancer. We studied immunohistochemically primary tumours of 104 patients with metastasised breast cancer who took part in a randomised multicentre trial comparing docetaxel to sequential methotrexate and 5-fluorouracil. Vessels were highlighted with factor VIII staining and counted microscopically. Microvessel density was compared with clinical response to chemotherapy and patient survival. The microvessel density of the primary tumour was not significantly associated with patient's response to chemotherapy, time to progression or overall survival in the whole patient population or in the docetaxel or methotrexate and 5-fluorouracil groups. However, disease-free survival was longer in patients with low microvessel density (P=0.01). These findings suggest that microvessel density of the primary tumour cannot be used as a predictive marker for chemotherapy response in advanced breast cancer
Spintronics: Fundamentals and applications
Spintronics, or spin electronics, involves the study of active control and
manipulation of spin degrees of freedom in solid-state systems. This article
reviews the current status of this subject, including both recent advances and
well-established results. The primary focus is on the basic physical principles
underlying the generation of carrier spin polarization, spin dynamics, and
spin-polarized transport in semiconductors and metals. Spin transport differs
from charge transport in that spin is a nonconserved quantity in solids due to
spin-orbit and hyperfine coupling. The authors discuss in detail spin
decoherence mechanisms in metals and semiconductors. Various theories of spin
injection and spin-polarized transport are applied to hybrid structures
relevant to spin-based devices and fundamental studies of materials properties.
Experimental work is reviewed with the emphasis on projected applications, in
which external electric and magnetic fields and illumination by light will be
used to control spin and charge dynamics to create new functionalities not
feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes
from the published versio
Die Futterqualit�t von Lihoraps und �lrettich bei gesteigerter Stickstoffd�ngung und variiertem Saattermin
Studie ueber die Behandlung und Beseitigung von Abwasserklaerschlamm, insbesondere ueber dessen Verwendung im Land- und Landschaftsbau sowie in der Forstwirtschaft Bearbeitungszeitraum: Juli 1978 - Juni 1979
Technische Informationsbibliothek Hannover: AC 5930. / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Method of approximation and calibration of the Mitscherlich-Spillman-Baule-von Boguslawski model
A modified mitscherlich equation for rainfed crop production in semi-arid areas: 1. Theory
The predictive value of bcl-2, bax, bcl-xL, bag-1, fas, and fasL for chemotherapy response in advanced breast cancer
Purpose: The purpose was to evaluate the utility of some bcl-2 family proteins fas and fasL as predictive indicators for chemotherapy response in advanced breast cancer. Experimental Design: Between October 1994 and October 1997, 283 patients with advanced breast cancer were included in a multicenter randomized study comparing docetaxel (D) to sequential methotrexate and 5-fluorouracil (MF) after anthracycline failure. The response rates (complete response + partial response) were 42 and 21% in the D and MF arms, respectively (P < 0.001). In 126 patients, histological blocks of primary tumors were available for inummohistochemical analysis of bax, bcl-2, bcl-xL, bag-1, fas and fasL. Results: Of the investigated factors, bag-1 correlated positively with bax, bcl-2, and fasL, and fasL correlated positively with fas and bax. None of these apoptosis-related factors was associated with a response to chemotherapy either in the whole patient population or in the D or MF arms. Interestingly, low bcl-2 expression was associated with shorter time to progression (P = 0.02) and shorter overall survival (OS; P = 0.001). High fasL expression showed a trend toward shorter OS. In multivariate backwards stepwise Cox analysis, in which histological grade and estrogen receptor status (ER) were also included, bcl-2 (P = 0.01) and fasL (P = 0.005) remained highly significantly associated with OS, whereas histological grade and ER lost their significance. Conclusions: None of the investigated apoptosis-related factors of primary tumor could predict the later response to either D or MF treatment. However, fasL and bcl-2 were strong prognostic factors. Patients who had tumors with high fasL and low bcl-2 expression had the shortest OS
C-erbB-2 expression does not predict response to docetaxel or sequential methotrexate and 5-fluorouracil in advanced breast cancer
Breast cancer patients with c-erbB-2-positive tumours seem to benefit from anthracycline-based adjuvant chemotherapy. The predictive value of c-erbB-2 for taxane sensitivity is not yet clear. The purpose of this study was to assess whether c-erbB-2 expression is associated with clinical sensitivity to docetaxel (T) or sequential methotrexate and 5-fluorouracil (MF). A total of 283 patients with metastatic breast cancer were initially enrolled in a randomised multicentre trial comparing docetaxel with sequential MF in advanced breast cancer. Paraffin-embedded blocks of the primary tumour were available for 131 patients (46%). c-erbB-2 status was determined by immunohistochemistry using a polyclonal antibody to the c-erbB-2 protein. C-erbB-2 expression was scored in a semi-quantitative fashion using a 0 to 3+ scale. Staining scores 2+ or greater were considered positive, Response evaluation was performed according to World Health Organization (WHO) recommendations. Overall 54 (42%) patients had c-erbB-2-positive tumours. There was no association between treatment outcome and c-erbB-2 overexpression. The overall response rates (RR) (n = 128) among c-erbB-2 -negative and -positive patients were 35 and 44%, respectively (P=0.359). In the MF arm (n = 62), the RR was somewhat higher in the c-erbB-.2 overexpressors (33% versus 18%, P = 0. 18). In the docetaxel arm the RRs were very similar, regardless of the c-erbB-2 expression (53% versus 53%). While several studies have suggested a prognostic and putative predictive significance of c-erbB-2 overexpression in early breast cancer, the significance of c-erbB-2 expression as a predictive factor for response to various cytotoxic treatments in advanced breast cancer is still controversial. In this study, c-erbB-2 expression could not predict response to either MF or T. Thus, tumours over-expressing c-erbB-2 are not uniformly more sensitive to taxanes and c-erbB-2 expression cannot yet be applied clinically as a predictive factor for response in advanced breast cancer