Standard Classical Methods Research Articles

Classical solvability to the free boundary problem for a foam drainage equation. II. From the interface to the bottom

We study a nonlinear partial differential equation describing the evolution of a foam drainage in one dimensional case which was proposed by Goldfarb et al. in 1988 in order to investigate the flow of liquid through channels (Plateau borders) and nodes (intersections of four channels) between the bubbles, driven by gravity and capillarity. Its mathematical studies so far are mainly restricted within numerical and particular solutions; as for mathematical analysis of it there are only a few. We prove that the free boundary problem for the foam drainage equation in the region below an interface to the bottom in a foam column admits a unique global-in-time classical solution by the standard classical mathematical method, the maximum principle. Moreover, the existence of its steady solution and its stability are shown.

Classical solvability to the free boundary problem for a foam drainage equation. I. From the top to the interface

We study a nonlinear partial differential equation describing the evolution of a foam drainage in one dimensional case which was proposed by Goldfarb et al. [Izv. Akad. Nauk SSSR Mekh. Ghidk. Gaza 2, 103–108 (1988)] in order to investigate the flow of liquid through channels (Plateau borders) and nodes (intersections of four channels) between the bubbles, driven by gravity and capillarity. Its mathematical studies so far are mainly restricted within numerical and particular solutions; as for mathematical analysis of it there are only a few. We prove that the free boundary problem for the foam drainage equation in the region from the top to the interface in a foam column admits a unique global-in-time classical solution by the standard classical mathematical method, the maximum principle and the comparison theorem. Moreover, the existence of its steady solution and its stability are discussed.

Distance-based paper analytical device for the determination of dissolved inorganic carbon concentration in freshwater

Dissolved inorganic carbon (DIC) levels in freshwaters play a key role in the equilibrium of the carbon cycle between the atmosphere, water and living beings. Standard classical methods for DIC determination generally involve bulky and expensive equipment used in centralized laboratories, resulting in time-consuming processes that do not allow for adequate monitoring in the field. In order to address this challenge, we have developed a distance-based paper analytical device (PAD) for on-site determination of DIC in water. The portable, cost-effective and easy-to-use device was based on the miniaturization and integration of a classical acid-base colorimetric titration on a paper channel, enabling an accurate determination of DIC in less than 20 min. The length of the blue colored line in the detection channel after being filled with the sample was related to the DIC concentration in the sample. The reagent solution used to modify the titration channel was optimized so that DIC concentrations in the range 50–1000 mg L−1 could be measured. The long-term stability of the paper-based device was also evaluated, demonstrating a working stability for more than 70 days after their fabrication, an important characteristic for in-the-field analysis. Finally, the PAD was validated with different water samples, i.e. tap water, commercial bottled drinking water and water samples from a mine, with excellent agreement between the results obtained from the PAD and the standard method. This demonstrates the high potential of the proposed paper analytical device to quantify DIC in situ by minimally-trained personnel without the need for peripheral equipment, which represents an important advance compared to the current limited analysis systems.

Secret-free security: a survey and tutorial

“Classical keys,” i.e., secret keys stored permanently in digital form in nonvolatile memory, appear indispensable in modern computer security—but also constitute an obvious attack target in any hardware containing them. This contradiction has led to perpetual battle between key extractors and key protectors over the decades. It is long known that physical unclonable functions (PUFs) can at least partially overcome this issue, since they enable secure hardware without the above classical keys. Unfortunately, recent research revealed that many standard PUFs still contain other types of “secrets” deeper in their physical structure, whose disclosure to adversaries breaks security as well: Examples include the manufacturing variations in SRAM PUFs, the power-up states of SRAM PUFs, or the signal delays in Arbiter PUFs. Most of these secrets have already been extracted in viable attacks in the past, breaking PUF-security in practice. A second generation of physical security primitives now shows potential to resolve this remaining problem, however. In certain applications, so-called Complex PUFs, SIMPLs/PPUFs, and UNOs are able to realize not just hardware that is free of classical keys in the above sense, but completely “secret-free” instead. In the resulting hardware systems, adversaries could hypothetically be allowed to inspect every bit and every atom, and learn any information present in any form in the system, without being able to break security. Secret-free hardware would hence promise to be innately and permanently immune against any physical or malware-based key-extraction: There simply is no security–critical information to extract anymore. Our survey and tutorial paper takes the described situation as starting point, and categorizes, formalizes, and overviews the recently evolving area of secret-free security. We propose the attempt of making hardware completely secret-free as promising endeavor in future hardware designs, at least in those application scenarios where this is logically possible. In others, we suggest that secret-free techniques could be combined with standard PUFs and classical methods to construct hybrid systems with notably reduced attack surfaces.

Classical solvability to the initial boundary value problem for a forced foam drainage equation

In this paper we study a nonlinear partial differential equation describing the evolution of a forced foam drainage in one dimensional case. A foam drainage equation was proposed by Goldfarb et al. [5] in 1988 in order to investigate the flow of liquid through channels (Plateau borders) and nodes (intersections of four channels) between the bubbles, driven by gravity and capillarity. Mathematical studies on a foam drainage equation so far are restricted within numerical and particular solutions; as for mathematical analysis of it there are only a few. This paper is aimed at proving that the initial boundary value problem for the forced foam drainage equation admits a unique global-in-time classical solution by the standard classical mathematical method, the maximum principle and comparison theorem. Moreover, the existence of its steady solution and its stability are shown. This is the first rigorous mathematical result for a series of researches on this equation.

STABILITY STUDY OF MODIFIED MUSTA-TRIPHALADIAVALEHA WITH RESPECT TO BASELINE MICROBIAL PROFILE USED IN THALASSEMIA MAJOR

Introduction: stability study of Modified Musta- Triphaladi Avaleha was done for 12 months (1 year) to know the stability of formulation in reference of its phyto-constituents and microbial growth therein. Modi-fied Musta-Triphaladi Avaleha have been used in Thalassemia children as an adjuvant therapy prepared with various herbal product. Methods: Modified Musta-Triphaladi Avaleha was made in Pharmacy with standard classical method (Avaleha Kalpana) as per AFI part-1 (The Ayurvedic formulary of India, part-1 part- A) In present study, stability with respect to its Microbial profile of Modified Musta-Triphaladi Ava-leha carried out. Avaleha was stored in 2 plastic containers during different climatic condition. Avaleha were studied at regular intervals for a period of 1 month to analysis Mycological findings and presence of Microorganisms by wet mount preparation and Gram stain test respectively. Results: At the end of study both Avaleha container has not present of microbes after 1 year of preparation, even in different climate and temperature. Conclusion: Since it is traditional Avaleha kalpana, the shelf life period was about one year (Sharangdhar Samhita) The presented study reflects that Microbiological findings of Modified Musta-Triphaladi Avaleha was negative at room temperature, warm and cold, dry and humid condition.

Antimicrobial Resistance, Virulence Determinants, and Biofilm Formation of Enterococcus Species From Ready-to-Eat Seafood.

Enterococcus species form an important population of commensal bacteria and have been reported to possess numerous virulence factors considered significantly important in exacerbating diseases caused by them. The present study was designed to characterize antibiotic-resistant and virulent enterococci from ready-to-eat (RTE) seafood. A total of 720 RTE shrimp samples comprising sauced shrimp (n = 288), boiled shrimp (n = 216), and smoked shrimp (n = 216) obtained from open markets in Delta State, Nigeria, were assessed. Standard classical methods and polymerase chain reaction (PCR) were used in identifying the Enterococcus species. Potential virulence factors (β-hemolysis, gelatinase activity, S-layer, and biofilm formation) were assessed using standard procedures. The antibiotic susceptibility profile of the identified enterococci isolates was assayed using the Kirby–Bauer disc diffusion method. PCR was further used to screen selected antibiotic resistance and virulence genes. Prevalence of Enterococcus species from shrimp varieties is as follows: sauced, 26 (9.03%); boiled, 6 (2.78%); and smoked, 27 (12.50%), with an overall prevalence of 59 (8.19%) based on the occurrence of black hallow colonies after incubation. Enterococcus species detected include E. faecalis, 17 (28.8%); E. faecium, 29 (49.2%); E. gallinarum, 6 (10.2%); E. casseliflavus, 2 (3.4%); E. hirae, 3 (5.1%); and E. durans, 2 (3.4%). Biofilm occurrence among the shrimp varieties is as follows: 19/26 (73.1%) for sauced shrimps, 5/6 (83.3%) for boiled shrimps, and 16/27 (59.3%) for smoked shrimps. The phenotypic expression of the enterococci virulence revealed the following: S-layer, 59 (100%); gelatinase production, 19 (32.2%); and β-hemolysis, 21 (35.6%). An average of 3–11 virulence genes were detected in the Enterococcus species. The resistance profile of Enterococcus species is as follows: erythromycin, 29 (49.2%); vancomycin, 22 (37.3%); and tetracycline, 27 (45.8%). The frequency of occurrence of antibiotic resistance genes from the phenotypic resistant enterococci isolates to the macrolide, glycopeptide, and tetracycline antibiotics is as follows: ermA, 13/29 (44.8%); vanA, 14/22 (63.6%); tetA, 14/27 (51.9%); tetM, 15/27 (55.6%); ermB, 4/29 (13.8%); and vanB, 5/22 (22.7%). Findings from this study reveal the antibiotic resistance of enterococci strains of such species as E. durans, E. casseliflavus, E. gallinarum, and E. hirae. This study further revealed that RTE food products are reservoirs of potential virulent enterococci with antibiotic-resistant capabilities. This provides useful data for risk assessment and indicates that these foods may present a potential public health risk to consumers.

EVALUATING THE PERFORMANCE OF ATP BIOLUMINESCENCE METHOD BY COMPARISON WITH CLASSICAL CULTURAL METHOD

Verification of the performance of the sanitation procedure is as important as the actual application. The methods that are going to be used for such verification needs to be user friendly and rapid resulting to apply the corrective actions promptly. Additionally, these methods should also be reliable besides their fast resulting. ATP bioluminescence method is recommended to be a solution for such procedures for many years. In this present study, our aim was to evaluate the performance of ATP bioluminescence method by comparison with golden standard classical cultural method. For this we performed parallel testing on surfaces which were experimentally contaminated with different types of microorganisms. The results showed that ATP bioluminescence gives more reliable results in surfaces which do not have any physical dirt and are contaminated with high level of microorganisms. The most reliable results were obtained from Salmonella contaminated surfaces.

Identification of Better Gene Expression Data for Mosquito Species Classification Using Radial Basis Function Network Methodology

Background: Investigation in bioinformatics has developed promptly in latest years owing to improvements in sequence excavating techniques. Gene sequences in DNA are supplemented with great extent of information, but the intricacy and complexity of this information causes difficulty in analyzing it by using standard classical methods of classification. In this work, a Radial Basis Function Network (RBFN) methodology with self-network arrangement is presented for identification of mosquito species based on the genetic design content of ITS2 ribosomal DNA sequences. Methods: A number of data sequences in varying sizes of different vectors corresponding to Anopheline, Aedes and Culex genera are used to develop genera specific as well as comprehensive RBFN species identifiers. The recall and generalization ability of the proposed species identifiers are analyzed and further validated through bootstrap validation method. The genera specific RBFN identifiers are found to provide accurate identification of mosquito species of individual genera. However, the comprehensive RBFN model is found to exhibit better species identification ability and can be advantageously used for species identification of more mosquito genera. Results & Conclusion: The results demonstrate the usefulness of the RBFN methodology for accurate identification of mosquito species depending on the nucleotide data of ITS2 ribosomal DNA sequences.

Heavy metal levels, physicochemical properties and microbial diversity of soil matrix from university solid waste collection sites in Benin City, Nigeria

This study was carried out to assess the microbial, physicochemical and heavy metal characteristics of soil samples from five different waste collection sites within the University of Benin, Benin City and evaluated using standard analytical and classical microbiological methods. The heavy metal concentration includes Zn (4.45±0.00 - 5.76±0.02 mg g−l); Cd (1.59±0.00 - 2.54±0.00 mg g−l); and Fe (1.02±0.02 - 1.07±0.00 mg g−l). The physicochemical properties include pH (4.91±0.01 - 5.82±0.04); TOC (6.49±0.01 - 7.65±0.02 %); NO2 − (29.32±0.07 - 32.81±0.11 mg g−l); and SO4 2− (47.30±0.12 - 63.25±0.04 mg g−l). The mean of culturable heterotrophic and coliform bacteria ranged from 4.03×107 ± 0.35 - 4.51×108 ± 0.12 CFU/g and 1.02×104 ± 0.12 - 3.10×105 ± 0.02 CFU/g respectively. At p-value < 0.01 level EC significantly correlates total heterotrophic bacteria (r= 0.971); coliform bacteria significantly correlate NO3 − (r= 0.989); while clay significantly but negatively correlates coliform bacteria (r= -0.989). Some of the bacteria isolated and identified from the waste collection sites include Klebsiella oxytoca, Enterobacter aerogenes, Staphylococcus aureus, Pseudomonas putida, and Bacillus macerans. Findings from this study reveal that the municipal solid waste on the collection sites has impacts on the indicator variables of the resident soil as well as serving as breeding sites for pathogenic organisms.Keywords: solid waste, environmental hazard, soil quality, pathogens

Classical molecular dynamics simulation of electronically non-adiabatic processes.

Both classical and quantum mechanics (as well as hybrids thereof, i.e., semiclassical approaches) find widespread use in simulating dynamical processes in molecular systems. For large chemical systems, however, which involve potential energy surfaces (PES) of general/arbitrary form, it is usually the case that only classical molecular dynamics (MD) approaches are feasible, and their use is thus ubiquitous nowadays, at least for chemical processes involving dynamics on a single PES (i.e., within a single Born-Oppenheimer electronic state). This paper reviews recent developments in an approach which extends standard classical MD methods to the treatment of electronically non-adiabatic processes, i.e., those that involve transitions between different electronic states. The approach treats nuclear and electronic degrees of freedom (DOF) equivalently (i.e., by classical mechanics, thereby retaining the simplicity of standard MD), and provides "quantization" of the electronic states through a symmetrical quasi-classical (SQC) windowing model. The approach is seen to be capable of treating extreme regimes of strong and weak coupling between the electronic states, as well as accurately describing coherence effects in the electronic DOF (including the de-coherence of such effects caused by coupling to the nuclear DOF). A survey of recent applications is presented to illustrate the performance of the approach. Also described is a newly developed variation on the original SQC model (found universally superior to the original) and a general extension of the SQC model to obtain the full electronic density matrix (at no additional cost/complexity).

Splitting-methods based on Approximate Matrix Factorization and Radau-IIA formulas for the time integration of advection diffusion reaction PDEs

A family of splitting methods for the time integration of evolutionary Advection Diffusion Reaction Partial Differential Equations (PDEs) semi-discretized in space by Finite Differences is obtained. The splitting is performed in the Jacobian matrix by using the Approximate Matrix Factorization (AMF) and by considering up to three inexact Newton Iterations applied to the two-stage Radau IIA method along with a very simple predictor. The overall process allows to reduce the storage and the algebraic costs involved in the numerical solution of the multidimensional linear systems to the level of 1D-dimensional linear systems with small bandwidths.Some specific AMF-Radau methods are constructed after studying the expression for the local error in semi-linear equations, and their linear stability properties are widely studied. The wedge of stability of the methods depends on the number of splittings used for the Jacobian matrix of the spatial semidiscretized ODEs, Jh=∑j=1dJh,j, where h stands for the spatial grid resolution. A-stability is proven for the cases d=1,2, and A(0)-stability for any d≥1.Numerical experiments on a 3D semi-linear advection diffusion reaction test problem and a 2D-combustion model are presented. The experiments show that the methods compare well with standard classical methods in parabolic problems and can also be successfully used for advection dominated problems when some diffusion or stiff reactions are present. In the latter case the stability imposes restrictions on the number of splitting terms (d).

Use of copula functions for the reliability of series systems

Purpose– The purpose of this paper is to provide a new method to estimate the reliability of series system by using copula functions. This problem is of great interest in industrial and engineering applications.Design/methodology/approach– The authors introduce copula functions and consider a Bayesian analysis for the proposed models with application to the simulated data.Findings– The use of copula functions for modeling the bivariate distribution could be a good alternative to estimate the reliability of a two components series system. From the results of this study, the authors observe that they get accurate Bayesian inferences for the reliability function considering large samples sizes. The Bayesian parametric models proposed also allow the assessment of system reliability for multicomponent systems simultaneously.Originality/value– Usually, the studies of systems reliability engineering assume independence among the component lifetimes. In the approach the authors consider a dependence structure. Using standard classical inference methods based on asymptotical normality of the maximum likelihood estimators for the parameters the authors could have great computational difficulties and possibly, not accurate inference results, which there is not found in the approach.

Diagnosis of Pneumocystis pneumonia: evaluation of four serologic biomarkers

The diagnosis of Pneumocystis pneumonia (PCP) relies on microscopic visualization of Pneumocystis jirovecii organisms or DNA detection in pulmonary specimens. This study aimed to assess the usefulness of (1–3)-β-d-glucan (BG), Krebs von den Lungen-6 antigen (KL-6), lactate dehydrogenase (LDH) and S-adenosyl methionine (SAM) as serologic biomarkers in the diagnosis of PCP. Serum levels of BG, KL-6, LDH and SAM were investigated in 145 Portuguese patients, 50 patients from the Netherlands, 25 Spanish patients and 40 Portuguese blood donors. Data on clinical presentation, chest imaging and gasometry tests were available. PCP cases were confirmed by microscopy and PCR techniques. A cost-effectiveness analysis was performed. BG was found to be the most reliable serologic biomarker for PCP diagnosis, followed by KL-6, LDH and SAM. The BG/KL-6 combination test was the most accurate serologic approach for PCP diagnosis, with 94.3% sensitivity and 89.6% specificity. Although less sensitive/specific than the reference standard classic methods based on bronchoalveolar lavage followed by microscopic or molecular detection of P. jirovecii organisms, the BG/KL-6 test may provide a less onerous procedure for PCP diagnosis, as it uses a minimally invasive and inexpensive specimen (blood), which may be also a major benefit for the patient's care. The BG/KL-6 combination test should be interpreted within the clinical context, and it may be used as a preliminary screening test in patients with primary suspicion of PCP, or as an alternative diagnostic procedure in patients with respiratory failure or in children, avoiding the associated risk of complications by the use of bronchoscopy.

A Study of single nucleotide polymorphism fragments of the aur gene metalloprotease strains of Straphylococcus aureus isolated from the skin of patients with atopic dermatitis

to study the heterogeneity of internal fragments of the aur gene coding a proteolytic enzyme aureolysin in strains of Staphylococcus aureus with different enzymatic activity, which were allocated with the affected skin of patients with atopic dermatitis. the study included 125 patients aged 1 to 35 years old with the diagnosis of atopic dermatitis. 100 clinical strains of Staphylococcus aureus were studied in monoculture. Identification of the strains of Staphylococcus aureus in skin was performed using standard classical methods. Specific biochemical microtests using a set of APIs Staph 20 (bioMerieux SA, France) were conducted to confirm the obtained results. Reference strains of S. aureus ATCC 29213, NCTC at 8.325 were used. Specific aur gene loci were detected by the method of multiplex polymerase chain reaction. Proteolytic activity was determined by the ability to split the substrate (human IgG, Sigma) into fragments using as inhibitors of matrix 0.01-0.1M solutions of sodium EDTA. The sequencing of the amplified areas of aur gene, including the preliminary stages of separation and purification of DNA, was performed by Syntol, Moscow. different strains of the conservative plot amplicon fragment of aur contains up to 9 polymorphic nucleotides. The index of the nucleotide diversity for proteolytic active strains was less (Pi = 0.04) than for proteolytically inactive (Pi = 0.07), p < 0.05. It should be noted that all proteolytically active strains were isolated from the skin of patients with high and moderate severity of atopic dermatitis (67.8 +/- 5.4 points on SCORAD scale) with erythematous form of the disease. The inactive strains were allocated in patients of older age with reduced severity of atopic dermatitis (with the dry form of skin lesions).

Preserving the continuity of round ligament along with hernia sac in indirect inguinal hernia repair in female children does not increase the recurrence rate of hernia. Experience with 217 cases

In the standard classical method of indirect inguinal hernia (IIH) repair in female children, after transligation of hernia sac along with round ligament at the level of internal ring, the distal portion is divided or cut off, thereby removing a possible future support for the internal genital organs. In this article, we propose a modification to the standard technique for IIH repair which preserves the continuity of round ligament along with hernia sac without increasing the recurrence rate. In a 3-year prospective clinical trial, from March 2007 to March 2010, IIH repairs were performed on 217 female children. In all of these cases, the hernia sac along with round ligament is only transligated at the level of internal ring and a window is created in the distal portion of the sac to prevent a hydrocele formation and the continuity of round ligament along with hernia sac was preserved. The charts of these patients were then analyzed to determine if recurrence had occurred. In addition, we noted any other early postoperative complications such as wound infection, bleeding, and tolerance. Within the 25-month mean follow-up period (6-36 months), none of the patients developed any of the above-mentioned complications. The most important result of this study was that preserving the continuity of round ligament along with hernia sac did not increase the rate of recurrence. On the basis of results obtained from this study, we conclude that preserving the continuity of round ligament along with hernia sac in female children during IIH repair does not increase the rate of recurrence, and is less intrusive to the normal anatomy of the inguinal region and needs less time to do.

Studying functional dynamics in bio-molecules using accelerated molecular dynamics

Many biologically important processes such as enzyme catalysis, signal transduction, ligand binding and allosteric regulation occur on the micro- to millisecond time-scale. Despite the sustained and rapid increase in available computational power and the development of efficient simulation algorithms, molecular dynamics (MD) simulations of proteins and bio-machines are generally limited to time-scales of tens to hundreds of nano-seconds. In this perspective article we present a comprehensive review of Accelerated Molecular Dynamics (AMD), an extended biased potential molecular dynamics approach that allows for the efficient study of bio-molecular systems up to time-scales several orders of magnitude greater than those accessible using standard classical MD methods, whilst still maintaining a fully atomistic representation of the system. Compared to many other approaches, AMD affords efficient enhanced conformational space sampling without any a priori understanding of the underlying free energy surface, nor does it require the specific prior definition of a reaction coordinate or a set of collective variables. Successful applications of the AMD method, including the study of slow time-scale functional dynamics in folded proteins and the conformational behavior of natively unstructured proteins are discussed and an outline of the different variants and extensions to the standard AMD approach is presented.

Inelastic electron collisions with Rydberg atoms

The standard classical method of computer simulation is used for evaluation of the inelastic cross section in electron collisions with a highly excited (Rydberg) atom. In the course of collision, the incident and bound electrons move along classical trajectories in the Coulomb field of the nucleus, and the scattering parameters are averaged over many initial conditions. The reduced ionization cross section of a Rydberg atom by electron impact approximately corresponds to that of atoms in the ground states with valence s-electrons and coincides with the results of the previous Monte Carlo calculations. The cross section of an atom transition between Rydberg atom states as a result of electron impact is used for finding the stepwise ionization rate constant of atoms in collisions with electrons or the rate constant of three-body electron-ion recombination in a dense ionized gas because these processes are determined by kinetics of highly excited atom states. Surprisingly, the low-temperature limit of electron temperatures is realized when the electron thermal energy is lower than the atom ionization potential by about three orders of magnitude, as follows from the kinetics of excited atom states.

A semi-parametric Bayesian approach to the instrumental variable problem

We develop a Bayesian semi-parametric approach to the instrumental variable problem. We assume linear structural and reduced form equations, but model the error distributions non-parametrically. A Dirichlet process prior is used for the joint distribution of structural and instrumental variable equations errors. Our implementation of the Dirichlet process prior uses a normal distribution as a base model. It can therefore be interpreted as modeling the unknown joint distribution with a mixture of normal distributions with a variable number of mixture components. We demonstrate that this procedure is both feasible and sensible using actual and simulated data. Sampling experiments compare inferences from the non-parametric Bayesian procedure with those based on procedures from the recent literature on weak instrument asymptotics. When errors are non-normal, our procedure is more efficient than standard Bayesian or classical methods.

A Semi-Parametric Bayesian Approach to the Instrumental Variable Problem

We develop a Bayesian semi-parametric approach to the instrumental variable problem. We assume linear structural and reduced form equations, but model the error distributions non-parametrically. A Dirichlet process prior is used for the joint distribution of structural and instrumental variable equations errors. Our implementation of the Dirichlet process prior uses a normal distribution as a base model. It can therefore be interpreted as modeling the unknown joint distribution with a mixture of normal distributions with a variable number of mixture components. We demonstrate that this procedure is both feasible and sensible using actual and simulated data. Sampling experiments compare inferences from the non-parametric Bayesian procedure with those based on procedures from the recent literature on weak instrument asymptotics. When errors are non-normal, our procedure is more efficient than standard Bayesian or classical methods.