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Search Results: 1 - 10 of 4399 matches for " Boris Bodelle "
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Dose Efficiency in Dual Source High-Pitch Computed Tomography of the Chest  [PDF]
Boris Bodelle, Thomas Lehnert, Martin Beeres, Thomas Josef Vogl, Boris Schulz
Advances in Computed Tomography (ACT) , 2014, DOI: 10.4236/act.2014.34008
Abstract:

Objectives: Evaluation of radiation efficiency of dual source high-pitch (DSHP) chest CT in comparison to single source technique with special regards to individual patient anatomy. Methods: 150 consecutive patients who underwent chest CT with automated tube current modulation were evaluated retrospectively and divided into three study groups, each with an equal quantity of 50 patients (DSHP vs. single source 128 slices vs. single source 16 slices). By using a dedicated workstation, volumetric analyses of each of the scanned anatomic area were performed and correlated to the individual dose length product (DLP). The calculated result was defined as dose efficiency. Results: DLP was 203 mGycm (DSHP), vs. 269 mGycm (single source) vs. 273 mGycm (16 slice CT). The total patient volume was lowest in the dual source group with 18956.3 cm3 (vs. 22481.2 cm3 vs. 22133.8 cm3). With regards to the DLP, the calculated dose efficiency of dual source CT was better than the 128 slice CT (p = 0.045) and the 16 slice CT (p < 0.01). Conclusions: DSHP CT has considerably better dose efficiency compared to 16 slice CT. Compared to 128 slice single source technique, the high-pitch mode does not cause any dose penalty when performing chest CT.

Evaluation of Multiparametric MRI of the Prostate: Impact of Standardized Examination Protocols and the Endorectal Coil  [PDF]
Finn Rampoldt, Frank Huebner, Stephan Zangos, Andreas Bucher, Jan-Erik Scholtz, Moritz Kaup, Sebastian Fischer, Thomas J. Vogl, Boris Bodelle
Open Journal of Medical Imaging (OJMI) , 2020, DOI: 10.4236/ojmi.2020.101003
Abstract:

Purpose: The aim of the present study was to evaluate the patient population, different MRI examination protocols and the patient’s acceptance of the endorectal coil in the diagnosis of prostate cancer regarding the current discussion in PI-RADS v2.1. Material and Methods: In our institute, 256 patients were examined with different protocols and separated into six groups. The value of the different MRI protocols was identified by analyzing sensitivity, specificity, negative predictive value and positive predictive value. The patient population was tested for statistically significant differences in their characteristics to detect a distortion of the results. The patients acceptance of endorectal coil was evaluated by a query. Results: In total 4.7% of the patients would not recommend a MRI examination because of subjective physical strain and 65.6% of all patients subjectively saw a benefit in the examination in regard to an optimal diagnostic process. The protocol groups reached a sensitivity from 66.7% - 100%, a specificity

Cubic Root Extractors of Gaussian Integers and Their Application in Fast Encryption for Time-Constrained Secure Communication  [PDF]
Boris Verkhovsky
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2011, DOI: 10.4236/ijcns.2011.44024
Abstract: There are settings where encryption must be performed by a sender under a time constraint. This paper de-scribes an encryption/decryption algorithm based on modular arithmetic of complex integers called Gaus-sians. It is shown how cubic extractors operate and how to find all cubic roots of the Gaussian. All validations (proofs) are provided in the Appendix. Detailed numeric illustrations explain how to use the method of digital isotopes to avoid ambiguity in recovery of the original plaintext by the receiver.
Primality Testing Using Complex Integers and Pythagorean Triplets  [PDF]
Boris Verkhovsky
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.59062
Abstract: Prime integers and their generalizations play important roles in protocols for secure transmission of information via open channels of telecommunication networks. Generation of multidigit large primes in the design stage of a cryptographic system is a formidable task. Fermat primality checking is one of the simplest of all tests. Unfortunately, there are composite integers (called Carmichael numbers) that are not detectable by the Fermat test. In this paper we consider modular arithmetic based on complex integers; and provide several tests that verify the primality of real integers. Although the new tests detect most Carmichael numbers, there are a small percentage of them that escape these tests.
Deterministic Algorithm Computing All Generators: Application in Cryptographic Systems Design  [PDF]
Boris Verkhovsky
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.511074
Abstract: Primitive elements play important roles in the Diffie-Hellman protocol for establishment of secret communication keys, in the design of the ElGamal cryptographic system and as generators of pseudo-random numbers. In general, a deterministic algorithm that searches for primitive elements is currently unknown. In information-hiding schemes, where a primitive element is the key factor, there is the freedom in selection of a modulus. This paper provides a fast deterministic algorithm, which computes every primitive element in modular arithmetic with special moduli. The algorithm requires at most O(log2p) digital operations for computation of a generator. In addition, the accelerated-descend algorithm that computes small generators is described in this paper. Several numeric examples and tables illustrate the algorithms and their properties.
Public-Key Cryptosystems with Secret Encryptor and Digital Signature  [PDF]
Boris Verkhovsky
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2013, DOI: 10.4236/ijcns.2013.61001
Abstract:

This paper describes and compares a variety of algorithms for secure transmission of information via open communication channels based on the discrete logarithm problem that do not require search for a generator (primitive element). Modifications that simplify the cryptosystem are proposed, and, as a result, accelerate its performance. It is shown that hiding information via exponentiation is more efficient than other seemingly simpler protocols. Some of these protocols also provide digital signature/sender identification. Numeric illustrations are provided.

The Analysis of the Equilibrium Cluster Structure in Supercritical Carbon Dioxide  [PDF]
Boris Sedunov
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.312A119
Abstract:

The monomer fraction density based analysis of precise thermophysical data for pure fluids is developed to study the molecular structures in supercritical fluids in general and in CO2 in particular. The series expansion by powers of the monomer fraction density of the potential energy density is used to discover the cluster structure in supercritical fluids and the clusters’ bond energies in CO2. The method of clusters separation between classes of loose and dense clusters in the CO2 supercritical fluid is developed. The method of the energetically averaged number of dense clusters is developed to study the mechanism of the soft structural transition between the gas-like and liquid-like fluids in the supercritical CO2.

Faster Method for Secure Transmission of Information with Sender Identification  [PDF]
Boris Verkhovsky
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2013, DOI: 10.4236/ijcns.2013.62009
Abstract:

This paper describes an algorithm for secure transmission of information via open communication channels based on the discrete logarithm problem. The proposed algorithm also provides sender identification (digital signature). It is twice as fast as the RSA algorithm and requires fifty per cent fewer exponentiations than the ElGamal cryptosystems. In addition, the algorithm requires twice less bandwidth than the ElGamal algorithm. Numerical examples illustrate all steps of the proposed algorithm: system design (selection of private and public keys), encryption, transmission of information, decryption and information recovery.

Thermal Analysis of Thermophysical Data for Equilibrium Pure Fluids  [PDF]
Boris Sedunov
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.47A2002
Abstract:

The thermal analysis of precise thermophysical data for pure fluids from electronic databases is developed to investigate the molecular interaction mechanisms and parameters and the structural features of heterogeneities in fluids. The method is based on the series expansion of thermophysical values by powers of the monomer fraction density. Unlike the virial expansion by powers of the total density, the series expansion terms in this method directly reflect properties of the corresponding cluster fractions. The internal energy had been selected among thermophysical properties as the most informative for this method. The thermal analysis of its series expansion coefficients permits to estimate the temperature dependence of the pair bond parameters, the clusters’ bond energies and equilibrium constants, the structural transitions between dominating isomers of clusters. The application of method to different pure fluids, including noble and molecular gases with van der Waals and polar molecular interactions, brings unknown clusters’ characteristics for the fluids under investigation. The thermal analysis of the ordinary and heavy Water vapors points on no trivial isotopic effects. The unpredictable growth of the pair bond energy with temperature in Alkanes points on existence in hydrocarbons of some unknown molecular interaction forces in addition to dispersion forces.

The Equilibrium Thermal Physics of Supercritical Fluids  [PDF]
Boris Sedunov
International Journal of Analytical Mass Spectrometry and Chromatography (IJAMSC) , 2013, DOI: 10.4236/ijamsc.2013.12013
Abstract:

To discover particular features of pure supercritical fluids, important for the supercritical fluid extraction and cleaning technologies, the preprocessed and generalized experimental data from the US National Institute of Standards and Technology (NIST) online database have been analyzed. The soft transition between gas-like and liquid-like structures in pure supercritical fluids has been considered in comparison with the abrupt vapor-liquid phase transition. A rough, diffused and boiling boundary between these structures in conditions of extra high gravity is opposed to a flat vapor-liquid boundary at a moderate gravity. The model for molecular diffusivity in carbon dioxide at temperatures near the critical temperature discovers its proportionality to the monomer fraction density. The cluster fraction based model for small molecular weight solids’ solubility in supercritical fluids has been suggested and successfully compared with the well-known experimental results for the solubility of silica in water.The model shows that at growing pressure the dissolution process has already startedin a real gas and discovers the cluster fractions’ role in the solubility process.

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