445 research outputs found
High-performance liquid chromatography analysis of mezlocillin, piperacillin, their degradation products, and of ioxitalamic acid in plasma and urine of healthy volunteers
In plasma and urine of 10 healthy volunteers after intravenous administration of 4 g mezlocillin and piperacillin, respectively, the parent compounds as well as degradation products were assayed by high-performance liquid chromatography. Ioxitalamic acid, a renal contrast medium, was administered simultaneously, in order to measure the glomerular filtration rate, and to control the collection of 24-h urine. As metabolite of mezlocillin the corresponding penicilloic acid only was found, whereas in the case of piperacillin a further degradation product was observed. Half of the doses given was recovered in the urine as unchanged drugs, and in addition 5-10% as metabolites. No differences were found in the pharmacokinetic behaviour of both antibiotics
Anomalous quantum chaotic behavior in nanoelectromechanical structures
It is predicted that for sufficiently strong electron-phonon coupling an
anomalous quantum chaotic behavior develops in certain types of suspended
electro-mechanical nanostructures, here comprised by a thin cylindrical quantum
dot (billiard) on a suspended rectangular dielectric plate. The deformation
potential and piezoelectric interactions are considered. As a result of the
electron-phonon coupling between the two systems the spectral statistics of the
electro-mechanic eigenenergies exhibit an anomalous behavior. If the center of
the quantum dot is located at one of the symmetry axes of the rectangular
plate, the energy level distributions correspond to the Gaussian Orthogonal
Ensemble (GOE), otherwise they belong to the Gaussian Unitary Ensemble (GUE),
even though the system is time-reversal invariant.Comment: 4 pages, pdf forma
Periodic Orbits in Polygonal Billiards
We review some properties of periodic orbit families in polygonal billiards
and discuss in particular a sum rule that they obey. In addition, we provide
algorithms to determine periodic orbit families and present numerical results
that shed new light on the proliferation law and its variation with the genus
of the invariant surface. Finally, we deal with correlations in the length
spectrum and find that long orbits display Poisson fluctuations.Comment: 30 pages (Latex) including 11 figure
Quantum chaos in nanoelectromechanical systems
We present a theoretical study of the electron-phonon coupling in suspended
nanoelectromechanical systems (NEMS) and investigate the resulting quantum
chaotic behavior. The phonons are associated with the vibrational modes of a
suspended rectangular dielectric plate, with free or clamped boundary
conditions, whereas the electrons are confined to a large quantum dot (QD) on
the plate's surface. The deformation potential and piezoelectric interactions
are considered. By performing standard energy-level statistics we demonstrate
that the spectral fluctuations exhibit the same distributions as those of the
Gaussian Orthogonal Ensemble (GOE) or the Gaussian Unitary Ensemble (GUE),
therefore evidencing the emergence of quantum chaos. That is verified for a
large range of material and geometry parameters. In particular, the GUE
statistics occurs only in the case of a circular QD. It represents an anomalous
phenomenon, previously reported for just a small number of systems, since the
problem is time-reversal invariant. The obtained results are explained through
a detailed analysis of the Hamiltonian matrix structure.Comment: 14 pages, two column
Prognostic value of microvessel density in stage II and III colon cancer patients:a retrospective cohort study
Background Microvessel density (MVD), as a derived marker for angiogenesis, has been associated with poor outcome in several types of cancer. This study aimed to evaluate the prognostic value of MVD in stage II and III colon cancer and its relation to tumour-stroma-percentage (TSP) and expression of HIF1A and VEGFA. Methods Formalin-fixed paraffin-embedded (FFPE) colon cancer tissues were collected from 53 stage II and 54 (5-fluorouracil-treated) stage III patients. MVD was scored by digital morphometric analysis of CD31-stained whole tumour sections. TSP was scored using haematoxylin-eosin stained slides. Protein expression of HIF1A and VEGFA was determined by immunohistochemical evaluation of tissue microarrays. Results Median MVD was higher in stage III compared to stage II colon cancers (11.1% versus 5.6% CD31-positive tissue area, p <0.001). High MVD in stage II patients tended to be associated with poor disease free survival (DFS) in univariate analysis (p = 0.056). In contrast, high MVD in 5FU-treated stage III patients was associated with better DFS (p = 0.006). Prognostic value for MVD was observed in multivariate analyses for both cancer stages. Conclusions MVD is an independent prognostic factor associated with poor DFS in stage II colon cancer patients, and with better DFS in stage III colon cancer patients treated with adjuvant chemotherapy
Lymph Node Negative Colorectal Cancers with Isolated Tumor Deposits Should Be Classified and Treated As Stage III
BACKGROUND: The prognostic role of pericolic or perirectal isolated tumor deposits (ITDs) in node-negative colorectal cancer (CRC) patients is unclear. Rules to define ITDs as regional lymph node metastases changed in subsequent editions of the TNM staging without substantial evidence. Aim of this study was to investigate the correlation between ITDs and disease recurrence in stage II and III CRC patients. MATERIALS AND METHODS: The medical files of 870 CRC patients were reviewed. Number, size, shape, and location pattern of all ITDs in node-negative patients were examined in relation to involvement of vascular structures and nerves. The correlation between ITDs and the development of recurrent disease was investigated. RESULTS: Disease recurrence was observed in 50.0% of stage II patients with ITDs (13 of 26), compared with 24.4% of stage II patients without ITDs (66 of 270) (P <.01). Disease-free survival of ITD-positive stage II patients was comparable with that of stage III patients. Also within stage III, more recurrences were observed in ITD-positive patients compared with ITD-negative patients (65.1 vs. 39.1%, respectively). No correlation was found between size of ITDs and disease recurrence. More recurrences were seen in patients with irregularly shaped ITDs compared with patients with 1 or more smooth ITDs present. CONCLUSIONS: Because of the high risk of disease recurrence, all node-negative stage II patients with ITDs, regardless of size and shape, should be classified as stage III, for whom adjuvant chemotherapy should be considere
Casimir force on amplifying bodies
Based on a unified approach to macroscopic QED that allows for the inclusion
of amplification in a limited space and frequency range, we study the Casimir
force as a Lorentz force on an arbitrary partially amplifying system of
linearly locally responding (isotropic) magnetoelectric bodies. We demonstrate
that the force on a weakly polarisable/magnetisable amplifying object in the
presence of a purely absorbing environment can be expressed as a sum over the
Casimir--Polder forces on the excited atoms inside the body. As an example, the
resonant force between a plate consisting of a dilute gas of excited atoms and
a perfect mirror is calculated
Practitioner’s Section: Integrated Resource Efficiency Analysis for Reducing Climate Impacts in the Chemical Industry
Reducing greenhouse gas emissions of the material-intensive chemical industry requires an integrated analysis and optimization of the complex production systems including raw material and energy use, resulting costs and environmental and climate impacts. To meet this challenge, the research project InReff (Integrated Resource Efficiency Analysis for Reducing Climate Impacts in the Chemical Industry) has been established. It aims at the development of an IT-supported modeling and evaluation framework which is able to comprehensively address issues of resource efficiency and climate change within the chemical industry, e.g. the minimization of material and energy intensity and consequently greenhouse gas emissions, without compromising on production performance. The paper presents background information on resource efficiency and the research project, an ideal-typical decision model for resource efficiency analysis, the conceptual approach for an IT-based integration platform as well as the case study design at the industrial project partners’ sites. These first results are linked to future activities and further research questions are highlighted in the concluding section
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