Dose/frequency: A critical factor in the administration of glucan as immunostimulant to Indian white shrimp Fenneropenaeus indicus

The immunostimulatory effect of an alkali insoluble glucan extracted from marine yeast isolate Candida sake S165 was tested in Fenneropenaeus indicus. Post larvae (PL) of F. indicus, fed glucan incorporated diet at varying concentrations (0.05, 0.1, 0.2, 0.3, 0.4 g glucan/100 g feed) for 21 days were challenged orally with white spot syndrome virus (WSSV). Maximum survival was observed in PL fed the 0.2% glucan incorporated diet. Subsequently the feed incorporated with 0.2% glucan was fed to F. indicus post larvae at different feeding intervals, i.e. daily, once every two days, once every five days, once every seven days and once every ten days. After 40 days, the prawns were challenged orally with WSSV and post challenge survival was recorded. Shrimp feed containing 0.2% glucan when administered once every seven days gave maximum survival. This was supported by haematological data obtained from adult F. indicus, i.e. total haemocyte count, phenoloxidase activity and nitroblue tetrazolium reduction (NBT). The present observation confirms the importance of dose and frequency of administration of immunostimulants in shrimp health management

Area and Volume Calculation of Necrotic Tissue regions of heart using Interpolation

This paper attempts to develop an improved tool, which would read two dimensional(2D) cardiac MRI images and compute areas and volume of the scar tissue. Here the computation would be done on the cardiac MR images to quantify the extent of damage inflicted by myocardial infarction on the cardiac muscle (myocardium) using Interpolation

Influence of the buffer environment on the Relative Biological Effectiveness of carbon ion radiation, investigated by Scanning Force Microscopy and gel electrophoresis

This work focuses on the analysis of the influence of environment on the relative biological effectiveness (RBE) of carbon ions on molecular level. Due to the high relevance of RBE for medical applications, such as tumor therapy, and radiation protection in space, DNA damages have been investigated in order to understand the biological efficiency of heavy ion radiation. The contribution of this study to the radiobiology research consists in the analysis of plasmid DNA damages induced by carbon ion radiation in biochemical buffer environments, as well as in the calculation of the RBE of carbon ions on DNA level by mean of scanning force microscopy (SFM). In order to study the DNA damages, besides the common electrophoresis method, a new approach has been developed by using SFM. The latter method allows direct visualisation and measurement of individual DNA fragments with an accuracy of several nanometres. In addition, comparison of the results obtained by SFM and agarose gel electrophoresis methods has been performed in the present study. Sparsely ionising radiation, such as X-rays, and densely ionising radiation, such as carbon ions, have been used to irradiate plasmid DNA in trishydroxymethylaminomethane (Tris buffer) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES buffer) environments. These buffer environments exhibit different scavenging capacities for hydroxyl radical (HO0), which is produced by ionisation of water and plays the major role in the indirect DNA damage processes. Fragment distributions have been measured by SFM over a large length range, and as expected, a significantly higher degree of DNA damages was observed for increasing dose. Also a higher amount of double-strand breaks (DSBs) was observed after irradiation with carbon ions compared to X-ray irradiation. The results obtained from SFM measurements show that both types of radiation induce multiple fragmentation of the plasmid DNA in the dose range from D = 250 Gy to D = 1500 Gy. Using Tris environments at two different concentrations, a decrease of the relative biological effectiveness with the rise of Tris concentration was observed. This demonstrates the radioprotective behavior of the Tris buffer solution. In contrast, a lower scavenging capacity for all other free radicals and ions, produced by the ionisation of water, was registered in the case of HEPES buffer compared to Tris solution. This is reflected in the higher RBE values deduced from SFM and gel electrophoresis measurements after irradiation of the plasmid DNA in 20 mM HEPES environment compared to 92 mM Tris solution. These results show that HEPES and Tris environments play a major role on preventing the indirect DNA damages induced by ionising radiation and on the relative biological effectiveness of heavy ion radiation. In general, the RBE calculated from the SFM measurements presents higher values compared to gel electrophoresis data, for plasmids irradiated in all environments. Using a large set of data, obtained from the SFM measurements, it was possible to calculate the survive rate over a larger range, from 88% to 98%, while for gel electrophoresis measurements the survive rates have been calculated only for values between 96% and 99%. While the gel electrophoresis measurements provide information only about the percentage of plasmids DNA that suffered a single DSB, SFM can count the small plasmid fragments produced by multiple DSBs induced in a single plasmid. Consequently, SFM generates more detailed information regarding the amount of the induced DSBs compared to gel electrophoresis, and therefore, RBE can be calculated with more accuracy. Thus, SFM has been proven to be a more precise method to characterize on molecular level the DNA damage induced by ionizing radiations.

Unrestricted hartree-fock calculation of the ionization potential of small Hg_n clusters

The ionization potential of small Hg_n clusters has been calculated. For the first time good agreement with experimental results has been obtained. It is shown that interatomic Coulomb interactions are important. The energy of Hg_n^+ is calculated using the unrestricted inhomogeneous Hartree-Fock approximation. As a consequence of a change in the charge distribution in Hg_n^+ , we obtain an abrupt change in the slope of the ionization potential at the critical cluster size n_cr ~ 14. The presented results are expected to be valid for covalent clusters in between ionized van der Waals clusters and metallic clusters.

Calculation of the electronic properties of neutral and ionized divalent-metal clusters

The electronic properties of neutral and ionized divalent-metal clusters have been studied using a microscopic theory, which takes into account the interplay between van der Waals (vdW) and covalent bonding in the neutral clusters, and the competition between hole delocalization and polarization energy in the ionized clusters. By calculating the ground-state energies of neutral and ionized. Hg_n clusters, we determine the size dependence of the bond character and the ionization potential I_p(n). For neutral Hg_n clusters we obtain a transition from van del Waals to covalent behaviour at the critical size n_c ~ 10-20 atoms. Results for I_p(Hg_n) with n \le 20 are in good agreement with experiments, and suggest that small Hg_n^+ clusters can be viewed as consisting of a positive trimer core Hg_3^+ surrounded by n - 3 polarized neutral atoms.

An attempt on the calculation of relativistic potential energy curves: noble gas difluorides

Total energy SCF calculations were performed for noble gas difluorides in a relativistic procedure and compared with analogous non-relativistic calculations. The discrete variational method with numerical basis functions was used. Rather smooth potential energy curves could be obtained. The theoretical Kr - F and Xe - F bond distances were calculated to be 3.5 a.u. and 3.6 a.u. which should be compared with the experimental values of 3.54 a.u. and 3.7 a.u. Although the dissociation energies are off by a factor of about five it was found that ArF_2 may be a stable molecule. Theoretical ionization energies for the outer levels reproduce the experimental values for KrF_2 and XeF_2 to within 2 eV.

An ab-initio calculation of the Coulomb explosion of N_2 after heavy-ion bombardement

Self-consistent-field calculations for the total potential energy of highly ionized N_2 molecules are presented. We compare these calculations to the experimentally observed energy released in the Coulomb explosion of ionized N_2 molecules created after collision with fast heavy ions. The most important electronic states of the fragment ions are determined.

Many-electron relativistic calculation and interpretation of atomic processes in time dependent heavy-ion scattering

The time dependence of a heavy-ion-atom collision system is solved via a set of coupled channel equations using energy eigenvalues and matrix elements from a self-consistent field relativistic molecular many-electron Dirac-Fock-Slater calculation. Within this independent particle model we give a full many-particle interpretation by performing a small number of single-particle calculations. First results for the P(b) curves for the Ne K-hole excitation for the systems F{^8+} - Ne and F{^6+} - Ne as examples are discussed.

Calculation of isomer shift in Mössbauer spectroscopy

The approximations normally used in the calculation of the isomer shift are compared with the exact expressions using Dirac-Slater orbitals and a three-parameter Fermi-type nuclear charge distribution. The nonuniformity of the electronic density over the nuclear volume affects the results. Different choices of the nuclear surface thickness t and the radius c in the protonic density P_N (\gamma) also affects the isomer shift differently even though the values are chosen to yield a given value of \delta . The change in the electronic charge density which is caused by the alteration of P_N (\gamma) in the ground state and excited state of the nucleus is discussed using two extrememodels and the possible influence on the observable isomer shift is estimated.

Calculation of the hyperfine structure transition energy and lifetime in the one-electron Bi^82+ ion

We calculate the energy and lifetime of the ground state hyperfine structure transition in one-electron Bi^82+ . The influence of various distributions of the magnetic moment and the electric charge in the nucleus ^209_83 Bi on energy and lifetime is studied.

Numerical comparison between Maxwell stress method and equivalent multipole approach for calculation of the dielectrophoretic force in octupolar cell traps

This work presents detailed numerical calculations of the dielectrophoretic force in octupolar traps designed for single-cell trapping. A trap with eight planar electrodes is studied for spherical and ellipsoidal particles using an indirect implementation of the boundary element method (BEM). Multipolar approximations of orders one to three are compared with the full Maxwell stress tensor (MST) calculation of the electrical force on spherical particles. Ellipsoidal particles are also studied, but in their case only the dipolar approximation is available for comparison with the MST solution. The results show that the full MST calculation is only required in the study of non-spherical particles.

Compositional ideas in the bayesian analysis of categorical data with application to dose finding clinical trials

Compositional random vectors are fundamental tools in the Bayesian analysis of categorical data. Many of the issues that are discussed with reference to the statistical analysis of compositional data have a natural counterpart in the construction of a Bayesian statistical model for categorical data. This note builds on the idea of cross-fertilization of the two areas recommended by Aitchison (1986) in his seminal book on compositional data. Particular emphasis is put on the problem of what parameterization to use

Fast calculation of the CAC convolution algorithm using the multinomial distribution function

The authors focus on one of the methods for connection acceptance control (CAC) in an ATM network: the convolution approach. With the aim of reducing the cost in terms of calculation and storage requirements, they propose the use of the multinomial distribution function. This permits direct computation of the associated probabilities of the instantaneous bandwidth requirements. This in turn makes possible a simple deconvolution process. Moreover, under certain conditions additional improvements may be achieved

Exposición acumulada de polvo respirable como predictor de enfermedad respiratoria

En la minería de carbón se presenta exposición prolongada a polvo de carbón y a polvo de sílice en diferentes porcentajes, encontrándose una asociación con las alteraciones obstructivas, bronquitis crónica, Neumoconiosis de los trabajadores de carbón y Silicosis. Se han establecido varias formas de estimar el riesgo de desarrollar dichas enfermedades respiratorias no malignas secundarias a la exposición a estos polvos (carbón y sílice) en el ámbito ocupacional, siendo el cálculo de la exposición acumulada, la que ha demostrado mayor utilidad. Con el fin de establecer el riesgo de desarrollar alteraciones funcionales, a partir de la exposición acumulada de polvo respirable - y en los trabajadores de una empresa de minería a cielo abierto en Colombia, se estructuró este estudio de cohorte. Se contó con el registro de 566 trabajadores distribuidos en 29 Grupos de Exposición Similar (GES). El cálculo de la dosis acumulada se realizó considerando las medianas de exposición para cada GES y el tiempo de exposición de cada trabajador. Y posteriormente se estimó el riesgo empleando una regresión de poisson con varianza robusta. Los resultados más importantes del estudio muestran la exposición acumulada en niveles inferiores a los reportados en la literatura, sin embargo se encuentra un riesgo ligeramente elevado, IRR 1.000124 (IC95% 1 - 1.000248) en los expuestos, estimando que por cada unidad de medición de la exposición acumulada que se incremente, el riesgo de que aparezca una alteración respiratoria funcional se incrementa en 1.000124 veces entre los trabajadores expuestos y los no expuestos.