bluuebunny/crossref_metadata_2025 huggingface dataset:
MAXIMUM SECONDARY ELECTRON YIELD AND PARAMETERS OF SECONDARY ELECTRON YIELD OF METALS
Authors: XIE AI-GEN , UHM HAN-SUP , CHEN YUN-YUN , CHOI EUN-HA
Published: March 2016

On the basis of the free-electron model, the energy range of internal secondary electrons, the energy band of a metal, the formula for inelastic mean escape depth, the processes and characteristics of secondary electron emission, the probability of internal secondary electrons reaching surface and passing over the surface barrier into vacuum B as a function of original work function [Formula: see text] and the distance from Fermi energy to the bottom of the conduction band [Formula: see text] was deduced. According to the characteristics of creation of an excited electron, the definition of average energy required to produce an internal secondary electron [Formula: see text], the energy range of excited electrons and internal secondary electrons and the energy band of a metal, the formula for expressing [Formula: see text] using the number of valence electron of the atom V, [Formula: see text] and atomic number Z was obtained. Based on the processes and characteristics of secondary electron emission, several relationships among the parameters of the secondary electron emission and the deduced formulae for B and [Formula: see text], the formula for expressing maximum secondary electron yield of metals [Formula: see text] using Z, V, back-scattering coefficient r, incident energy of primary electron at which secondary electron yield reaches [Formula: see text], [Formula: see text] and [Formula: see text] was deduced and demonstrated to be true. According to the deduced formula for [Formula: see text] and the relationships among [Formula: see text] and several parameters of secondary electron emitter, it can be concluded that high [Formula: see text] values are linked to high V, Z and [Formula: see text] values, and vice versa. Based on the processes and characteristics of secondary electron emission and the deduced formulae for the B, [Formula: see text] and [Formula: see text], the influences of surface properties on [Formula: see text] were discussed.
TRIBOLOGICAL BEHAVIOR OF ELECTROLESS Ni–P COATINGS IN VARIOUS CORROSIVE ENVIRONMENTS
Authors: PANJA BIKASH , DAS SUMAN KALYAN , SAHOO PRASANTA
Published: March 2016

The present paper deals with the study of tribological characteristics, viz. friction and wear, of electroless Ni–P coating in corrosive environments (brine, acidic and alkaline) by varying different coating process parameters as well as varying the tribological testing parameters, viz. applied load and speed. The optimized results of coating process parameters for minimum friction and wear performance of the coating are presented. Moreover, a detailed study of the tribological behavior of the coating is undertaken individually for the three corrosive environments. The results obtained are compared among each other and also with the dry condition test of the coating. It is found that the friction coefficient of Ni–P coating decreases with increase in load for all environments. In case of wear, the wear rate of Ni–P coating gradually increases with increase in load for all mediums but the same decreases after 40[Formula: see text]N in brine and alkaline mediums. However, for acidic solution, the wear rate shows a continuous increasing trend. It is observed that alkaline and brine environments are favorable from friction and wear point of view of the coating, respectively. Microstructure study of the coatings is also performed and the coating is found to be of cauliflower-like morphology. The coating also exhibits amorphous structure in as-deposited condition, which gradually turns crystalline with heat treatment.
Finite p-groups all of whose 𝒜k-subgroups for a fixed k are metacyclic
Authors: Berkovich Yakov
Published: March 2016

Applying Blackburn’s classification of minimal nonmetacyclic [Formula: see text]-groups (see Lemma 2(a)), we prove that if [Formula: see text] and all [Formula: see text]-subgroups of a finite [Formula: see text]-group [Formula: see text] are metacyclic so is [Formula: see text].
DFT study on the mechanism of 1,3-hydrogen disposition in Isopentenyl pyrophosphate catalyzed by Isopentenyl pyrophosphate: Dimethylallyl pyrophosphate isomerase
Authors: Basak Atanu , Chakrabarty Kuheli , Ghosh Animesh , Das Gourab Kanti
Published: March 2016

Biosynthesis of polyterpenoid and related molecules are largely accomplished via mevalonate pathway. One of the vital steps in this pathway is the inter-conversion of two intermediates isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) catalyzed by IPP:DMAPP isomerase (IDI). The crystal structure of the enzyme, bound to the substrate analogues and inhibitors, revealed possible mechanism of this inter-conversion; however, none of them could affirm the true nature of the transition state through which the process is taking place. Our DFT study on the pathway of this isomerization reaction at the active site of the enzyme suggests a favorable concerted mechanism that occurs through a single transition structure without generating any carbocation intermediate. In this mechanism, the Cys-67 residue acts as proton donor whereas Glu-116 acts as proton acceptor. The mechanism also reveals the active involvement of other two components present at the active site. A crystallographic water molecule (Wat508) and Glu-87 assist to reprotonate the conjugate base of cysteine residue through a proton shuttle mechanism while forming the transition structure of the isomerization reaction.
Molecular dynamics simulations of cylindrical polyelectrolyte brushes in monovalent and multivalent salt solutions
Authors: Hao Qing-Hai , Chen Qian , Zheng Zhen , Liu Li-Yan , Liu Tie-Ju , Niu Xiao-Hui , Song Qing-Gong , Tan Hong-Ge
Published: March 2016

Molecular dynamics simulations are applied to investigate the cylindrical polyelectrolyte brushes in monovalent and multivalent salt solutions. By varying the salt valence and concentration, the brush thickness, shape factor of grafted chains, and distributions of monomers and ions in the solutions are studied. The simulation results show that the single osmotic pressure effect in the brush leads to changes in conformation in the presence of monovalent salt, while the ion exchange effect induces the collapse of the brushes in the multivalent salt solutions. Furthermore, the snapshots combined with the distributions of the end-monomers and the mean bond angles demonstrate a nonuniform stretching picture of the grafted chains, which is different with the chains tethered on the planar surface. The charge ratios between the ions trapped in the brush and the monomers are also calculated to elucidate the details of ion exchange process.
Some properties of windowed linear canonical transform and its logarithmic uncertainty principle
Authors: Bahri Mawardi , Ashino Ryuichi
Published: March 2016

Based on the relationship between the Fourier transform (FT) and linear canonical transform (LCT), a logarithmic uncertainty principle and Hausdorff–Young inequality in the LCT domains are derived. In order to construct the windowed linear canonical transform (WLCT), Gabor filters associated with the LCT is introduced. Using the basic connection between the classical windowed Fourier transform (WFT) and the WLCT, a new proof of inversion formula for the WLCT is provided. This relation allows us to derive Lieb’s uncertainty principle associated with the WLCT. Some useful properties of the WLCT such as bounded, shift, modulation, switching, orthogonality relation, and characterization of range are also investigated in detail. By the Heisenberg uncertainty principle for the LCT and the orthogonality relation property for the WLCT, the Heisenberg uncertainty principle for the WLCT is established. This uncertainty principle gives information how a complex function and its WLCT relate. Lastly, the logarithmic uncertainty principle associated with the WLCT is obtained.
Forces in the complex octonion curved space
Authors: Weng Zi-Hua
Published: March 2016

The paper aims to extend major equations in the electromagnetic and gravitational theories from the flat space into the complex octonion curved space. Maxwell applied simultaneously the quaternion analysis and vector terminology to describe the electromagnetic theory. It inspires subsequent scholars to study the electromagnetic and gravitational theories with the complex quaternions/octonions. Furthermore Einstein was the first to depict the gravitational theory by means of tensor analysis and curved four-space–time. Nowadays some scholars investigate the electromagnetic and gravitational properties making use of the complex quaternion/octonion curved space. From the orthogonality of two complex quaternions, it is possible to define the covariant derivative of the complex quaternion curved space, describing the gravitational properties in the complex quaternion curved space. Further it is possible to define the covariant derivative of the complex octonion curved space by means of the orthogonality of two complex octonions, depicting simultaneously the electromagnetic and gravitational properties in the complex octonion curved space. The result reveals that the connection coefficient and curvature of the complex octonion curved space will exert an influence on the field strength and field source of the electromagnetic and gravitational fields, impacting the linear momentum, angular momentum, torque, energy, and force and so forth.
Global existence and nonlinear diffusion of classical solutions to non-isentropic Euler equations with damping in bounded domain
Authors: Wu Fuzhou
Published: March 2016

We consider classical solutions to the initial boundary value problem for the non-isentropic compressible Euler equations with damping in several space dimensions. We establish a global existence theory for classical solutions to this system when the initial data are sufficiently small. We prove that the pressure and the velocity converge exponentially toward some constants, while the entropy and the density in general do not approach constants. Finally, we prove that, as the time goes to infinity, the pressure and the velocity components of the non-isentropic Euler equations with damping converge exponentially toward those of an associated nonlinear diffusion system, and the global existence of classical solutions to these nonlinear diffusion equations is also established.
Global existence of smooth solutions to relativistic string equations in Schwarzschild space-time for small initial data
Authors: He Chun-Lei , Huang Shou-Jun , Kong De-Xing
Published: March 2016

This paper is concerned with the motion of relativistic strings in Schwarzschild space-time. In a general framework, we first analyze the basic equations for the motion of a [Formula: see text]-dimensional extended object in a general enveloping space-time [Formula: see text], which is a given Lorentzian manifold, and then we investigate some important properties enjoyed by the equations for the motion of relativistic strings in Schwarzschild space-time. In particular, the equations are shown to form a totally linearly degenerate system of first-order hyperbolic equations in [Formula: see text] dimensions. Based on this observation and under suitable assumptions, we are able to prove the global existence of smooth solutions to the Cauchy problem for the equations of motion of relativistic strings (in Schwarzschild space-time) with sufficiently small arc length.
Analytical Approximate Prediction of Thermal Post-Buckling Behavior of the Spring-Hinged Beam
Authors: Sun Youhong , Wu Baisheng , Yu Yongping
Published: March 2016

This paper is concerned with thermal post-buckling of uniform isotropic beams with axially immovable spring-hinged ends. The ends of the beam with elastic rotational restraints represent the actual practical support conditions and the classical hinged and clamped conditions can be achieved as the limiting cases of the rotational spring stiffness. The governing differential–integral equation is solved by assuming suitable admissible function for lateral displacement and by employing the Galerkin method. A brief and explicit analytical approximate formulation is established to predict the thermal post-buckling behavior of the beam. The present analytical approximate expressions show excellent agreement with the corresponding numerical solutions based on the shooting method. This confirms the effectiveness and verifies the accuracy of the formulas established.
On the Perturbation Methods for Vibration Analysis of Linear Time-Varying Systems
Authors: Yang Xiao-Dong , Liu Ming , Zhang Wei , Qian Ying-Jing , Melnik Roderick V. N.
Published: March 2016

Some perturbation methods in the studying vibrations of the linear time-varying (LTV) system are discussed. Three classical perturbation methods, namely, averaging method, harmonic balance method, and multiple scales method with linear scales, have been used from a new perspective based on analytical approximations to the corresponding LTV ordinary differential equations. The deploying beam model has been taken as an example to validate the explicit approximate solutions obtained by these perturbation methods. It is demonstrated that such approximate solutions have good agreement with numerical and exact solutions, excluding the vicinity of the turning point.
Dependence of Thermal Shock Crack on Specimen Width for Ceramic Materials
Authors: Xu Xianghong , Yuan Wenjun , Tian Cheng
Published: March 2016

Knowledge of size effect of thermal shock properties of ceramics is a prerequisite in engineering applications. In the present study, the size effect of the cracking in the ceramic materials subjected to water quenching has been experimentally conducted. Based on the Rizk model, the equivalent specimen width of the elastic strip with cracks is introduced and modified to describe the effect of cracks on the deformation of the elastic strip underwater quenching. It is found that the simulation obtained from the proposed modified model is in good agreement with the experimental results. And the reasons for the size effect of crack depth and crack growth into the compressive region are well analyzed by theoretical results. The proposed model is expected to provide a powerful tool to characterize and predict the size effect on thermal shock crack of ceramic materials.
Effect of Au on the Performance of Porous Silicon/V2O5 Nanorods Heterojunctions to NO2 Gas
Authors: Yan Wenjun , Hu Ming , Liang Jiran , Wang Dengfeng , Wei Yulong , Qin Yuxiang
Published: March 2016

A novel composite of Au-functionalized porous silicon (PS)/V2O5 nanorods (PS/V2O5:Au) was prepared to detect NO2 gas. PS/V2O5 nanorods were synthesized by a heating process of pure vanadium film on PS, and then the obtained PS/V2O5 nanorods were functionalized with dispersed Au nanoparticles. Various analytical techniques, such as field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), have been employed to investigate the properties of PS/V2O5:Au. Herein, the PS/V2O5:Au sample exhibited improved NO2-sensing performances in response, stability and selectivity at room temperature (25[Formula: see text]C), compared with the pure PS/V2O5 nanorods. These phenomena were closely related to not only the dispersed Au nanoparticles acting as a catalyst but also the p-n heterojunctions between PS and V2O5 nanorods. Whereas, more Au nanoparticles suppressed the improvement of response to NO2 gas.
Modular group algebras with small Lie nilpotency indices
Authors: Siwach Reetu , Sharma R. K. , Sahai Meena
Published: March 2016

Let [Formula: see text] be a group and let [Formula: see text] be a field of characteristic [Formula: see text]. In this paper, we have classified the group algebras [Formula: see text] which are strongly Lie nilpotent of index [Formula: see text], [Formula: see text] or [Formula: see text].
Modeling and volume rendering approach of underwater three-dimensional acoustic energy field
Authors: Zeng Yanyang , Jia Panpan
Published: March 2016

The underwater acoustics is primary and most effective method for underwater object detection and the complex underwater acoustics battlefield environment can be visually described by the three-dimensional (3D) energy field. Through solving the 3D propagation models, the traditional underwater acoustics volume data can be obtained, but it is large amount of calculation. In this paper, a novel modeling approach, which transforms two-dimensional (2D) wave equation into 2D space and optimizes energy loss propagation model, is proposed. In this way, the information for the obtained volume data will not be lost too much. At the same time, it can meet the requirements of data processing for the real-time visualization. In the process of volume rendering, 3D texture mapping methods is used. The experimental results are evaluated on data size and frame rate, showing that our approach outperforms other approaches and the approach can achieve better results in real time and visual effects.
Experimental Validation of On-Field Measurement Method for a Heat Pump System with Internal Heat Exchanger
Authors: Goossens Maria , Riviere Philippe , Teuillieres Cedric , Tran Cong Toan , Cauret Odile , Marchio Dominique
Published: March 2016

Determining the on-field heating capacity and coefficient of performance (COP) of residential air-to-air heat pumps (HPs) is problematic, given that measuring accurately the enthalpy and, specifically, the mass flow rate of air is challenging. This paper validates a promising on-field performance measurement method for HPs with an internal heat exchanger (IHX) as vapor injection system using experimental data obtained from air-to-water heat pump prototype in several operating conditions. The method is based on refrigerant fluid measurements and component energy/mass balances. Nonintrusive sensors, such as surface temperature sensors, are used to estimate pressure and refrigerant mass flow rate in different types of heat pump systems, including air-to-air. Obtained results compared with intrusively measured reference values in steady-state conditions are in good agreement, suggesting that a comprehensive performance analysis can be conducted in already-installed high efficiency residential IHX air-to-water HPs, as well as internal heat exchanger air-to-air HPs.
Regular rotating electrically charged structures in nonlinear electrodynamics minimally coupled to gravity
Authors: Dymnikova Irina , Galaktionov Evgeny
Published: March 2016

In nonlinear electrodynamics minimally coupled to gravity, regular spherically symmetric electrically charged solutions satisfy the weak energy condition and have obligatory de Sitter center. By the Gürses-Gürsey algorithm they are transformed to regular axially symmetric solutions asymptotically Kerr-Newman for a distant observer. Rotation transforms de Sitter center into de Sitter equatorial disk embedded as a bridge into a de Sitter vacuum surface. The de Sitter surfaces satisfy [Formula: see text] and have properties of a perfect conductor and ideal diamagnetic. The Kerr ring singularity is replaced with the superconducting current which serves as a non-dissipative electromagnetic source of the asymptotically Kerr-Newman geometry. Violation of the weak energy condition is prevented by the basic requirement of electrodynamics of continued media.
Gravitational collapse of Vaidya spacetime
Authors: Vertogradov Vitalii
Published: March 2016

The gravitational collapse of generalized Vaidya spacetime is considered. It is known that the endstate of gravitational collapse, as to whether a black hole or a naked singularity is formed, depends on the mass function [Formula: see text]. Here we give conditions for the mass function which corresponds to the equation of the state [Formula: see text] where [Formula: see text] and according to these conditions we obtain either a black hole or a naked singularity at the endstate of gravitational collapse. Also we give conditions for the mass function when the singularity is gravitationally strong.
Hypermotion due to space-time deformation
Authors: Fil’chenkov Michael , Laptev Yuri
Published: March 2016

A superluminal motion (hypermotion) via M. Alcubierre’s warp drive is considered. Parameters of the warp drive have been estimated. The equations of starship geodesics have been solved. The starship velocity have been shown to exceed the speed of light, with the local velocity relative to the deformed space-time being below it. Hawking’s radiation does not prove to affect the ship interior considerably. Difficulties related to a practical realization of the hypermotion are indicated.
Simulation of laser ablation of metals for nanoparticles production
Authors: Davydov R. V. , Antonov V. I. , Davydova T. I.
Published: March 2016

In this paper a mathematical model for femtosecond laser ablation of metals is proposed, based on standard two-temperature model connected with 1D hydrodynamic equations. Wide-range equation of state has been developed. The simulation results are compared with experimental data for aluminium and copper. A good agreement for both metals with numerical results and experiment shows that this model can be employed for choosing laser parameters to better accuracy in nanoparticles production by ablation of metals.
Polarimetric sensors on the basis of CdS/CuInSe2 heterocontact: Influence of the heat treatment on photosensitivity spectrum
Authors: Rud’ V. Yu. , Rud’ Yu. V. , Terukov E. I.
Published: March 2016

CuInSe2 thin films were grown by vacuum evaporation of presynthesized material from a single source. The room-temperature photoconductivity spectra of the film show a strongly dependence on the evaporation conditions and, especially, on the evaporation temperature. A shift of the long-wavelenght photoactive absorption edge and the evolution of the photoconductivity spectra of the films were observed. The influence can be explained by allowing for deviations of the compositions of the condensed phase from CuInSe2 stoichiometry.
Bernstein-type inequality for a class of dependent random matrices
Authors: Banna Marwa , Merlevède Florence , Youssef Pierre
Published: March 2016

In this paper, we obtain a Bernstein-type inequality for the sum of self-adjoint centered and geometrically absolutely regular random matrices with bounded largest eigenvalue. This inequality can be viewed as an extension to the matrix setting of the Bernstein-type inequality obtained by Merlevède et al. [Bernstein inequality and moderate deviations under strong mixing conditions, in High Dimensional Probability V: The Luminy Volume, Institute of Mathematical Statistics Collection, Vol. 5 (Institute of Mathematical Statistics, Beachwood, OH, 2009), pp. 273–292.] in the context of real-valued bounded random variables that are geometrically absolutely regular. The proofs rely on decoupling the Laplace transform of a sum on a Cantor-like set of random matrices.
On the fluctuations of eigenvalues of multiplicative deformed unitary invariant ensembles
Authors: Vasilchuk Vladimir
Published: March 2016

We consider the ensemble of [Formula: see text] random matrices [Formula: see text], where [Formula: see text] and [Formula: see text] are non-random, unitary, having the limiting Normalized Counting Measure (NCM) of eigenvalues, and [Formula: see text] is unitary, uniformly distributed over [Formula: see text]. We find the leading term of the covariance of traces of resolvent of [Formula: see text] and establish the Central Limit Theorem for sufficiently smooth linear eigenvalue statistics of [Formula: see text] as [Formula: see text].
Post-glacial mud depocentre in the southern Beibu Gulf: acoustic features and sedimentary environment evolution
Authors: Ni Y. , Harff J. , Xia Z. , Waniek J. J. , Endler M. , Schulz-Bull D. E.
Published: March 2016

This study documents the Southern Beibu Gulf Mud Depocentre (SBGMD) for the first time using high-resolution sub-bottom seismic reflection profiles. The SBGMD is located near the southern mouth of the Beibu Gulf in water depths of 50–80 m, and covers an area of more than 11 000 km
2
. The acoustic architecture of the SBGMD is characterized by a homogenous seismic unit surrounded by an erosive area where gullies and sand/mud waves occur. The SBGMD unconformably overlies a parallel-bedded seismic unit.

Based on
14
C-dating, together with acoustic, lithological and geochemical analysis of gravity core SO31, which was sampled within the high-sedimentation-rate area of the SBGMD, the post-glacial sedimentary history may be summarized as follows: (1) from 12.8 to 11.6 cal ka BP, the SBGMD was deposited in a low-energy, brackish/freshwater and intensely terrestrial-influenced environment; (2) from 11.6 to 8.4 cal ka BP, the SBGMD underwent marine transgression; and (3) from 8.4 cal ka BP to present, a continuous shallow-marine environment has prevailed. Comparing the age and depth of the SBGMD base with the established sea-level curve, lacustrine sedimentation is predicted to have occurred in the SBGMD area before 12.8 cal ka BP.
Pediatric RSV Infection During Two Winter Seasons in British Columbia: A Role for Subgroup Analysis in Young Children?
Authors: Wilson E , Orvell C , Morrison B , Thomas E
Published: March 2016

Using a panel of eight monoclonal antibodies directed against the G, F and NP proteins of respiratory syncytial virus, 167 virus isolates from nasopharyngeal washing cultures at British Columbia Children’s Hospital during two consecutive epidemics were subgrouped. Slides made and frozen at the time of virus isolation or prepared from recovered frozen passage material, were assayed by indirect immunofluorescence. Of 85 strains tested in 1987–88, 54 (64%) were subgroup A, and 31 (36%) subgroup B. By contrast, of 82 strains tested in 1988–89 five (6%) were subgroup A and 77 (94%) subgroup B. Review of patient charts did not reveal significant differences in clinical course of patients infected with the two subgroups, but the risk of infection with subgroup A was significantly greater than the risk of subgroup B infection in younger patients.
The Cost of Health Care for AIDS Patients in Saskatchewan
Authors: Browne Kevin P , Shafran Steve D , Conly John M
Published: March 2016

The medical records of 19 patients with acquired immune deficiency syndrome (aids) were reviewed in an attempt to estimate their health care costs. The patients were all male, members of high risk groups and diagnosed between April 1985 and February 1988. Twelve of the patients died; they lived a mean of 240 days (range 0 to 580) after diagnosis, were admitted three times (range one to six) to hospital for 65 total days (range one to 148) for a cost per patient of $33,721 (range $2,768 to $64,981) for inpatient care. They made five (range zero to 25) office visits per patient costing $196 per patient (range $0 to $4,999) for outpatient care. The seven survivors (one was lost to follow‐up) have lived 375 days (range 186 to 551) since diagnosis, have been admitted to hospital two times (range zero to seven) for 30 total days (range zero to 86) for a total cost per patient of $14,223 (range $0 to $39,410) for inpatient care. They have made 11 office/emergency room visits (range zero to 46) costing in total $4322 (range $0 to $13,605) for outpatient care. The total expenditure was $546,332 ($28,754 per patient), of which total fees to physicians were $37,210 (6.8%), and estimated costs of laboratory tests $117,917 (21.6%), drugs $36,930 (6.7%), and medical imaging $20,794 (3.8%). Patients now deceased cost $416,445 (mean $34,704 per patient), accounting for 76.2% of overall expenditures. The average medical/surgical and drug costs per patient day in hospital were greater for aids patients than for the average medical/surgical patient in the authors’ institution.
Diagnosis of Cellulitis in the Immunocompromised Host
Authors: Carey Charles F , Dall Lawrence
Published: March 2016

A prospective study of diagnostic techniques in cellulitis was performed on 28 patients with malignancy. Twenty‐two (78%) of the fine needle aspiration cultures and 10 (35%) of the blood cultures were positive in this immunocompromised population. The incidence of positive fine needle aspiration cultures (P<0.005) or bacteremia (P<0.0005) was significantly higher than results obtained in an immunocompetent population with cellulitis at the same institution. Staphylococci or streptococci were recovered in 59% of positive cultures, while aerobic Gram‐negative bacilli grew in 33%. This study indicates that in the immunocompromised population with cellulitis, fine needle aspiration and blood cultures should be obtained, and the antibiotic regimen should cover Gram‐positive cocci and Gram‐negative bacilli pending the results of cultures.
Quality Control Assessment of Canadian Laboratories Testing for Lyme Disease
Authors: Artsob Harvey , Garvie Maxwell
Published: March 2016

In June 1990 a quality control assessment was undertaken of Canadian public health laboratories testing for antibodies to Borrelia burgdorferi, the etiological agent of Lyme disease. Twenty sera were distributed to nine laboratories, including 12 obtained from patients in Lyme endemic areas and presumed to be serological positives, and eight prescreened negative controls. Seventeen serological reports were submitted, comprising nine enzyme‐linked immunosorbent assays (elisa), six immunofluorescent assays and two Western blot assessments. Antibodies were detected in 11 of the 12 sera which had been presumed to be positive. Assuming 11 positive sera had been submitted, the test sensitivities varied from 88.9 to 100% by elisa, and 54.5 to 90.1% by immunofluorescent assay. Specificities were 100% for all but one elisa and one immunofluorescent assay assessment. The results indicate a satisfactory performance by elisa but a need for upgrading or replacement of some immunofluorescent assay tests.
Pyuria in Institutionalized Elderly Subjects
Authors: Rodgers K , Nicolle LE , McIntyre M , Harding GKM , Hoban D , Murray D
Published: March 2016

Two hundred and forty‐three urine specimens from 76 elderly institutionalized residents were obtained for urine culture, quantitative leukocyte count and urinalysis. Significant bacteriuria was present in 153 specimens (63%), including 33 (22%) with more than one organism. Pyuria (greater than or equal to 10 leukocytes/mm3) was present in 214 specimens (88%), including 116 (97%) with single organism bacteriuria, 27 (82%) with multiple organism bacteriuria, and 71 (80%) without significant bacteriuria. The leukocyte esterase test had a positive predictive value of 99% for pyuria but a negative predictive value of only 30%. The quantitative level of pyuria was associated with the level of proteinuria and inversely with pH. A relatively constant level of pyuria tended to persist over months to years in a given individual if bacteriuria persisted. Pyuria is significantly associated with bacteriuria in the institutionalized elderly, but is also common in the nonbacteriuric. The clinical significance of pyuria requires further assessment.
Prevention of Foodborne Listeriosis
Authors: Farber JM , Harwig J , Carter A
Published: March 2016

Listeria monocytogenes is a Gram‐positive, rod‐shaped bacterium which, although recognized in the medical literature as an opportunistic pathogen for the past 60 years, has only recently gained prominence as an important foodborne pathogen. Factors which make this organism unique among foodborne pathogens include its ability both to survive in foods under a variety of adverse conditions and to grow at low refrigeration temperatures. The organism is very widespread in the environment and can be found in a wide variety of foods. At least four major outbreaks definitively linked to the consumption of food containing L monocytogenes have occurred. In addition there have been a number of recent sporadic cases of listeriosis linked to the consumption of meat, fish and dairy products. The primary concern of the Health Protection Branch is contaminated foods in which L monocytogenes can grow well, and which would not normally be heated prior to consumption. Worldwide, the disease appears to be increasing in incidence, but definite links to foods are difficult to make. In most cases, individuals who come down with listeriosis include the immunocompromised, the elderly (older than 65 years) and pregnant women and their fetuses. Primary manifestations of the disease include meningitis, spontaneous abortion and septicemia. Mortality rates in foodborne listeriosis outbreaks are approximately 30%. Diagnosis of listeriosis usually requires isolation of the organism from sterile sites such as blood, cerebrospinal fluid, placenta and meconium and gastric aspirates from neonates. The recommended drug of choice is high dose intravenous ampicillin. Advice to physicians concerning measures to prevent foodborne listeriosis in high risk groups is reviewed. Included among these recommendations is avoidance of consumption of potentially hazardous foods such as soft cheese and raw products of animal origin.
Laboratory Confirmation of Lyme Disease
Authors: Schwan Tom G , Simpson Warren J , Rosa Patricia A
Published: March 2016

Lyme disease can be confirmed in the laboratory by isolation or detection of its causative agent, a tick‐borne spirochete Borrelia burgdorferi, or by a diagnostic change in the titre of antibodies specific to the agent. B burgdorferi can be isolated and cultivated in Barbour‐Stoenner‐Kelly II medium. It can be detected by light microscopy in tissue sections or, rarely, in blood smears using various staining methods. There is interest in the development of alternative detection methods, including identification of specific antigens of B burgdorferi in the urine of suspected cases and demonstration of the presence of species‐specific DNA using polymerase chain reaction assays. Currently, serological tests (indirect immunofluorescence assay, enzyme‐linked immunosorbent assay and Western immunoblot) are the most practical and available methods for confirming Lyme disease. The quest to improve the specificity and sensitivity of serological tests – for example, through the use of specific recombinant antigens – continues.
Imported Arbovirus Infections in Canada 1974‐89
Authors: Artsob Harvey , Spence Leslie
Published: March 2016

From 1974 to 1989, sera from symptomatic patients with histories of recent travel outside Canada were tested for antibodies to several arboviruses, principally of the alphavirus and flavivirus families. Diagnostic seroconversions were documented in 84 individuals from six provinces, including one alphavirus (Chikungunya) and 83 flavivirus seroconvertors. Dengue 1 virus was isolated from the blood of one patient. Most flavivirus seroconvertors were likely infected with dengue virus, but infections with tick‐borne encephalitis, St Louis encephalitis and Powassan viruses were also recognized. Patients had histories of recent travel to the Caribbean, South America, Asia, Africa, North America (outside Canada), Tahiti, Fiji and Europe. Possible imported infections due to Japanese encephalitis, Ross River, western equine encephalitis and Colorado tick fever viruses were also encountered.
Overview of the Clinical Manifestations of Borrelia burgdorferi Infection
Authors: Dattwyler Raymond J , Luft Benjamin J
Published: March 2016

Lyme disease, caused by the spirochete Borrelia burgdorferi, has classically been divided into three stages: erythema migrans; neurological or cardiac involvement; and arthritis. Rather than defining a set disease pattern, however, one should, more logically, conceptualize a progressive infection that may be localized or disseminated, acute or chronic. Erythema migrans, the earliest and most easily recognized manifestation of B burgdorferi infection, is an expanding annular erythematous skin lesion with a central clearing that develops soon after the bite of an infected ixodes tick. Musculoskeletal manifestations are common, with approximately one‐half of untreated individuals developing arthritis. Of these, only 10% have chronic arthritis. Invasion of the central nervous system occurs as the infection disseminates hematogenously, with encephalitis, myelitis and meningopolyneuritis being the most severe results. Acute cardiac involvement is recognized in up to 8% of adult patients, and less often in children. Early antibiotic treatment of the infection is highly effective.
Pneumocystis carinii: A Review of an Important Opportunistic Pathogen in AIDS
Authors: Gill M John , Read Ron
Published: March 2016

Since the first report of human infection with Pneumocystis carinii in 1942, cases of pneumonia due to this opportunistic pathogen have become increasingly common. Animal studies and clinical observations show that a significant depletion or dysfunction of T helper lymphocytes predisposes to clinical disease. Individuals with damaged T helper cells secondary to malignancies (eg, Hodgkin’s lymphoma), drugs (eg, cyclosporine, steroids), or certain infections (eg, human immunodeficiency virus) are at particular risk. Serological studies suggest that disease is most often secondary to the reactivation of an asymptomatic infection, usually acquired during childhood. Increasing shortness of breath, a nonproductive cough and hypoxia often preceded by several weeks of lethargy, fever and weight loss are the classical features of P carinii pneumonia in acquired immune deficiency syndrome. Bronchoalveolar lavage is usually the optimal diagnostic test. Immunofluorescent staining on liquified sputum induced by nebulized saline appears to be a promising and noninvasive test. Early empiric therapy with trimethoprim‐sulphamethoxazole (trimethoprim 5 mg‐sulphamethoxazole 25 mg/kg/day every 6 h) or intravenous pentamidine (4 mg/kg/day) for 21 days is usually effective, but infection is not eradicated, and clinical disease is likely to recur. Prophylaxis using aerosolized pentamidine reduces the risk of pulmonary disease but can predispose to extrapulmonary infection. Improved in vitro and in vivo models of human pneumocystis infection would significantly increase understanding of the molecular biology of the organism, the pathogenesis of disease, and the optimal therapeutic regimens.
Human Immunodeficiency Virus as a Sexually Transmitted Disease: Manitoba’s HIV Unlinked Seroprevalence Study
Authors: Sekla Laila , Hammond Gregory , Tate Robert , Stackiw Walter , Eibisch Gudrun , Shewchook Sherlyn
Published: March 2016

Objective: To determine the prevalence of human immunodeficiency virus (HIV)‐1 infections.

Design: An unlinked seroprevalence study on all ‘left over’ blood submitted for syphilis testing during three consecutive six month periods (April 1, 1990 to September 30, 1991). After the capture of demographic data, sera to be tested for antibodies were stripped of all personal identifiers and assigned a random number. The study fulfilled Canadian ethical guidelines.

Participants: Persons with a valid Manitoba Health Services Commission number were included only once in a study year. Persons were enrolled into one of five categories: infants, injection drug users, pregnant women, persons investigated for sexually transmitted diseases (STD) and routine testing.

Results: Of the 50,929 persons tested. 133 (0.26%) were positive, a low prevalence of HIV infections. A significant increase in positivity was noticed in the second study period. While 77.7% of those tested were women, only 10 (0.025%) were positive for HIV. The rate of positivity for pregnant women was 0.72 per 10,000 tested. Of the 11,314 males tested. 123 (1.08%) had antibodies. Most of the positives were males in the STD category residing in Winnipeg; for them, the rate of positivity increased by middle age, while the rate of testing decreased with each decade of age (from age 15 to 44 years).

Discussion/Recommendation: This is the first report from a sentinel laboratory in Canada of an unlinked seroprevalence study in persons with STD. Results suggest an urgent need to target strategies for the control of HIV for persons with STD, particularly males in urban centres, by routine HIV testing for STD patients.
The Search for Ixodes dammini and Borrelia burgdorferi in Nova Scotia
Authors: Bell Colin R , Specht Harold B , Coombs B Ann
Published: March 2016

Twenty‐four Ixodes dammini ticks (23 adults and one nymph) have been recovered in Nova Scotia since 1984. There has not been a systematic search for larvae and none has been identified. The recovery of the nymph from a road‐killed yellow throat bird, Geothypis trichas, in late May 1990 supports the contention that migrating birds are bringing deer ticks into the province every spring. In March and April 1991, four adult deer ticks were identified, suggesting that these ticks had overwintered. These deer tick specimens indicate that it is possible that I dammini is becoming established in Nova Scotia, if it is not already established. There has been no evidence for the existence of Borrelia burgdorferi in the province. The spirochete was not cultured from 650 Dermacentor variabilis ticks, nor were antibodies detected in a small sample of feral rodents using an indirect fluorescent antibody test. A survey of 137 dog sera samples, analyzed by enzyme‐linked immunosorbent assay, also proved negative. There has been no confirmed indigenous case of Lyme disease in Nova Scotia to date.
Urinary Tract Infections in Spinal Cord Injury Patients Undergoing Intermittent Catheterization Procedures
Authors: Kirkland Teresa , Taylor Geoffrey D
Published: March 2016

A prospective study was organized to assess whether feeding back infection rates to staff performing intermittent catheterization in spinal cord‐injured patients would produce a fall in urinary tract infection rates. Over a 12 month period, infection rates for such procedures were reported to unit staff: reporting was combined with educational programs emphasizing aseptic catheterization techniques and the importance ofhandwashing. Overall infection rates for the 12 month period were 13.3 per 1000 days of intermittent catheterization ‐ unchanged from the preceding six months (15.1 per 1000 days) by retrospective chart review. Likewise, there was no statistically significant downward trend during the prospective phase of the study. A wide variety of infecting organisms were found, of which Klebsiella species (39%), Escherichia coli (18%) and Enterobacter species (17%) were most common: most infections were asymptomatic. Patients with complete cord lesions at or above the sixth thoracic spinal cord segment (T6) had a much higher incidence of infection (73%) than those with incomplete lesions below T6 (33%).
STD Training in Canadian Medical Schools
Authors: Doherty Jo-Anne A , Jessamine A Gordon
Published: March 2016

OBJECTIVE: The emergence of the acquired immune deficiency syndrome in 1981 and the consequent publicity surrounding sexual behaviour has increased the likelihood that patients will seek medical advice. Sexually transmitted disease (STD) teaching and postgraduate medical programs in Canadian schools of medicine have not been adequately documented. Accordingly, the Laboratory Centre for Disease Control. Department of National Health and Welfare, sought to determine the magnitude and scope of STD training in these schools. DESIGN: A four page questionnaire sought information on preclinical, clinical and residency training in terms of the number of classroom and laboratory hours of instruction, the subspecialty responsible for providing the training, and the clinical ‘hands on’ experience of the teachers: each respondent was also asked to assess the quality and scope of instruction provided at his/her medical school. SETTING/PARTICIPANTS: The questionnaire was mailed to the Dean of each of the 16 schools of medicine in Canada: it was requested that the questionnaire be forwarded to and completed by the person responsible for STD training at the university. RESULTS: Thirteen schools (81%) completed the questionnaire. Each school indicated that some STD instruction was provided at the undergraduate level: the mean number of hours of classroom instruction was 6.1. Physicians with STD clinical ‘hands on’ experience were responsible for teaching in 12 schools. Infectious disease residents spent 4 to 80 h on STDs, while those from other residency programs where STD was not an elective spent 2 to 8 h. Each medical school was asked to provide an evaluation of its program. Only three respondents considered their STD training program adequate. The majority of schools responded that infectious disease residents received sufficient training but the training offered medical students and residents in other programs was less than adequate. The quality of teaching was considered ‘excellent’ in three schools, ‘good’ in nine, and ‘poorly co‐ordinated’ in one. CONCLUSIONS: There is no simple solution to ensure that every physician in Canada receives sufficient clinical training in STDs. Collaborative and cooperative efforts by federal, provincial and local governments, professional societies, licensing bodies, medical schools, residency programs, STD clinical directors and provincial and territorial directors of STD control, should be encouraged.
Bacterial Meningitis in HIV‐Infected Patients: Case Reports and Review of the Literature
Authors: Tommasini Robert , Fong Ignatius W
Published: March 2016

Meningitis is not an uncommon complication of the acquired immune deficiency syndrome. Purulent meningitis is not a well recognized infection in human immunodeficiency virus (HIV) positive patients. Three cases of bacterial meningitis caused by Streptococcus pneumoniae, Neisseria meningitidis and Listeria monocytogenes are presented. These cases illustrate that common community organisms may present in HIV positive patients. An acquired B cell defect may predispose to bacterial infections responsible for meningitis in HIV‐infected patients.
Epidemiological Studies of Nosocomial Infections with Pseudomonas aeruginosa Using a DNA Probe
Authors: Joffe A Mark , Volpel Kathy , Kibsey Pamela C , Paranchych William
Published: March 2016

A DNA probe encoding the Pseudomonas aeruginosa pilin gene has been developed in the authors’ laboratory and has been shown to be a useful epidemiological tool. In the present study this technology, together with other typing methods, has been used to define relatedness and possible transmission routes of P aeruginosa strains isolated in several hospital wards. Clusters of P aeruginosa infections, suspected to be the result of nosocomial transmission, developed in a general intensive care unit (ICU) and a neurosurgical ward/ICU, as well as in a burn unit, were studied using antibiograms, lipopolysaccharide‐serotyping, and gene probe analysis. Results of these studies demonstrated that each of the general and neurosurgical ICU isolates were different, making nosocomial transmission very unlikely. However, within the burn unit, patient isolates had identical profiles, suggesting that spread between patients was occurring or that a common source of infection was present. Changes in infection control measures within the unit were introduced and may have contributed to eradication of the outbreak. DNA probe studies were valuable in clarifying epidemiological relatedness of isolates that was not evident with the other typing strategies and identified a possible burn‐associated strain.
Praziquantel Failure in the Treatment of Fasciola hepatica
Authors: Patrick David Michael , Isaac-Renton Judith
Published: March 2016

A case of human fascioliasis is presented in which the patient remained symptomatic after treatment with praziquantel and other agents but eventually responded to bithionol. The difficulties in finding an efficacious and tolerable drug therapy for this condition are reviewed with reference to the life cycle and pathogenesis of the parasite. It is concluded that while bithionol remains the current drug of choice, triclabendazole may play a dominant role in the near future.