Study of Blood Porphyrin Spectral Profile for Diagnosis of Tumor Progression

Renal cell carcinoma (RCC) accounts for approximately 3% of new cancer incidence and mortality in the United States. Unfortunately many RCC masses remain asymptomatic and nonpalpable until they are advanced. Diagnosis and localization of early carcinoma play an important role in the prevention and curative treatment of RCC. The autofluorescence of blood porphyrin of healthy and tumor induced in male SCID mice was analyzed using fluorescence and excitation spectroscopy. A significant contrast between normal and tumor blood could be established. Blood porphyrin fluorophore showed enhanced fluorescence band (around 630 nm) in function of the tumor growth. This indicates that either the autofluorescence intensity of the blood fluorescence may provide a good parameter for the “first approximation” characterization of the tumor stage.     

Temperature Integration: An efficient procedure for calculation of free energy differences

We propose a method, Temperature Integration, which allows an efficient calculation of free energy differences between two systems of interest, with the same degrees of freedom, which may have rough energy landscapes. The method is based on calculating, for each single system, the difference between the values of lnZ$lnZ$ at two temperatures, using a Parallel Tempering procedure. If our two systems of interest have the same phase space volume, they have the same values of lnZ$lnZ$ at high-T$T$, and we can obtain the free energy difference between them, using the two single-system calculations described above. If the phase space volume of a system is known, our method can be used to calculate its absolute (versus relative) free energy as well. We apply our method and demonstrate its efficiency on a “toy model” of hard rods on a 1-dimensional ring.     

Pseudo-atom phase shifts of liquid metals and alloys

Ziman pseudo-atom phase shifts have been evaluated, as functions of l and k _F, for monovalent ions, using a pseudo-potential technique. The results of their application to a number of physical problems suggest that our data are reasonably accurate.     

Setting targets for surrogate-based optimization

In the context of surrogate-based optimization (SBO), most designers have still very little guidance on when to stop and how to use infill measures with target requirements (e.g., one-stage approach for goal seeking and optimization); the reason: optimum estimates independent of the surrogate and optimization strategy are seldom available. Hence, optimization cycles are typically stopped when resources run out (e.g., number of objective function evaluations/time) or convergence is perceived, and targets are empirically set which may affect the effectiveness and efficiency of the SBO approach. This work presents an approach for estimating the minimum (target) of the objective function using concepts from extreme order statistics which relies only on the training data (sample) outputs. It is assumed that the sample inputs are randomly distributed so the outputs can be considered a random variable, whose density function is bounded (a, b), with the minimum (a) as its lower bound. Specifically, an estimate of the minimum (a) is obtained by: (i) computing the bounds (using training data and the moment matching method) of a selected set of analytical density functions (catalog), and (ii) identifying the density function in the catalog with the best match to the sample outputs distribution and corresponding minimum estimate (a). The proposed approach makes no assumption about the nature of the objective functions, and can be used with any surrogate, and optimization strategy even with high dimensional problems. The effectiveness of the proposed approach was evaluated using a compact catalog of Generalized Beta density functions and well-known analytical optimization test functions, i.e., F2, Hartmann 6D, and Griewangk 10D and in the optimization of a field scale alkali-surfactant-polymer enhanced oil recovery process. The results revealed that: (a) the density function (from a catalog) with the best match to a function outputs distribution, was the same for both large and reduced samples, (b) the true optimum value was always within a 95% confidence interval of the estimated minimum distribution, and (c) the estimated minimum represents a significant improvement over the present best solution and an excellent approximation of the true optimum value.     

On the equivalence of quadratic optimization problems commonly used in portfolio theory

In the paper, we consider three quadratic optimization problems which are frequently applied in portfolio theory, i.e., the Markowitz mean–variance problem as well as the problems based on the mean–variance utility function and the quadratic utility. Conditions are derived under which the solutions of these three optimization procedures coincide and are lying on the efficient frontier, the set of mean–variance optimal portfolios. It is shown that the solutions of the Markowitz optimization problem and the quadratic utility problem are not always mean–variance efficient.     

Sampling in a weighted Sobolev space

We show that functions f in some weighted Sobolev space are completely determined by time-frequency samples ${\{f(t_n)\}}_{n\in \mathbb{Z}}\cup {\{\stackrel{?}{f}({\lambda }_k)\}}_{k\in \mathbb{Z}}$ along appropriate slowly increasing sequences ${\{t_n\}}_{n\in \mathbb{Z}}$ and ${\{{\lambda }_n\}}_{n\in \mathbb{Z}}$ tending to ±∞ as $n\to \pm \infty$.     

Reconstruction of thermally quenched glow curves in quartz

The experimentally measured thermoluminescence (TL) glow curves of quartz samples are influenced by the presence of the thermal quenching effect, which involves a variation of the luminescence efficiency as a function of temperature. The real shape of the thermally unquenched TL glow curves is completely unknown. In the present work an attempt is made to reconstruct these unquenched glow curves from the quenched experimental data, and for two different types of quartz samples. The reconstruction is based on the values of the thermal quenching parameter W (activation energy) and C (a dimensionless constant), which are known from recent experimental work on these two samples. A computerized glow-curve deconvolution (CGCD) analysis was performed twice for both the reconstructed and the experimental TL glow curves. Special attention was paid to check for consistency between the results of these two independent CGCD analyses. The investigation showed that the reconstruction attempt was successful, and it is concluded that the analysis of reconstructed TL glow curves can provide improved values of the kinetic parameters E, s for the glow peaks of quartz. This also leads to a better evaluation of the half-lives of electron trapping levels used for dosimetry and luminescence dating.     

Correlation Between Autofluorescence Intensity and Tumor Area in Mice Bearing Renal Cell Carcinoma

Protoporphyrin IX (PpIX) is a porphyrin derivative that is accumulated in cancerous tissue in consequence of the tumor-specific metabolic alterations. The aim of this study was to evaluate the accumulation of PpIX in mice bearing renal cell carcinoma by spectroscopy analysis. A total of 24 male Balb/c mice, 6 weeks old, were divided into six groups: Normal (without inoculation of tumor cells) and 4, 8, 13, 16, and 20 days after inoculation of tumor cells. The orthotopic tumor model of renal cancer was used. Murine renal cell carcinoma (Renca cells) were inoculated into the subcapsular space of the kidney. Normal and tumor-bearing kidneys in different progression stages were removed and analyzed by ex-vivo spectroscopy and by microscopy, for tumor histometric analysis. Emission spectra were obtained by exciting the samples at 405 nm. Significant differences between normal and tumor-bearing kidneys in autofluorescence shape occurred in the 600–700 nm spectral region. A good correlation was found between emission band intensity at 635 nm and the tumor area.     

Determination of the Apparent Molar Refraction and Partial Molar Volume at Infinite Dilution of Thiophene-, Pyrrole- and Furan-2-Carboxaldehyde Phenylhydrazone Derivatives in Acetonitrile at 293.15 K

High-precision densitometry and high-accuracy refractometry measurements of extremely dilute solutions of the thiophene-2- (TCPH), pyrrole-2- (PCPH) and furan-2-carboxaldehyde-phenylhydrazone (FCPH) compounds in acetonitrile have been obtained at 293.15 K. The partial molar volumes V ₂^∞ of each compound at infinite dilution were determined. The apparent molar refraction of these solutes at infinite dilution at 293.15 K has been experimentally determined within the Kohner-Geffcken-Grunwald-Haley approximation. The volumetric and refractometric results were interpreted in terms of the Pauling electronegativity and intrinsic molar volume of the heteroatom, and the aromaticity of the heterocyclic rings. The experimental results indicate that solute-solute interactions are negligible within the concentration range studied. Theoretical calculations at the DFT-B3LYP/6−311++G(3d,3p) level of molecular volumes support the interpretation that the volumetric contribution from the solute-solvent interactions to the limiting partial molar volumes of solutes are very small and thus solute molecules are isolated in this medium.