bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Bone Cement Failure Criteria With Applications to the Acetabular Region
Authors: Vasu R. , Carter D. R. , Harris W. H.
Published: June 2009

A strain energy density (SED) criterion based on a fracture mechanics approach was used to assess the possible failure of acetabular bone cement after total hip replacement. Stress distributions in the cement at the bone-cement interface were calculated using two-dimensional finite element analyses. The results indicate that increasing the thickness of bone cement reduces the risk of cement fracture. The addition of a metal backing to the polyethylene cup and retention of the sub-chondral bone further reduces the risk of failure. The SED criterion was found to predict the same critical regions as zones of possible cement failure as the von Mises’ criterion. Although either criterion can be used for predicting failure in this acetabular analysis both criteria are excessively conservative in predicting failure in regions where high principal compressive stresses are present. Further development of cement failure criteria are indicated.
Nonlinear Pulse Wave Reflection at an Arterial Stenosis
Authors: Pedley T. J.
Published: June 2009

A simple model is presented to analyze the effect of stenoses of different severities in a long elastic tube or artery on the pressure and flow-rate wave forms incident upon them. Wave propagation in the undisturbed tube is taken to be linear; nonlinearity arises from the quadratic dependence of stenosis pressure drop on flow rate. Before the model can be applied in practice, important physiological questions must be answered; e.g.: (a) Can the incident wave form and mean proximal pressure be regarded as given input? (b) Is the mean flow rate given, or does the peripheral resistance remain constant? Results are given on the assumption that the answer to (a) is yes. The principal conclusion is that the input impedance spectrum of a stenosed artery depends strongly on the incident waveform, as well as on the severity of the stenosis and on the distance from it at which measurements are made. There is good qualitative agreement with the results of experiments and of other models.
Muscle Pathway Geometry in the Heart Wall
Authors: Streeter D. D. , Ramon Ceon
Published: June 2009

Muscle fiber pathways in the heart wall are described. Procedures are introduced which permit data to be standardized from cadaver and animal hearts fixed at different points of the cardiac cycle or obtained in vivo from patients with different ejection fractions and heart masses. Design criteria are also developed here to construct a hypothetical standard left ventricle to compare the data from different hearts. The equations allow the nested set of toroidal fiber-shells to be depicted with typical muscle fiberpaths. With this formulation the heart wall and typical elements in it can be shown computergraphically as they move from the contracted state to the distended. Man-made fiber structures that simulate the fail-safe shockload absorbing features of the heart can now be designed and tested computergraphically by use of the mathematical procedures described here.
Constitutive Equations for the Lung Tissue
Authors: Lanir Y.
Published: June 2009

The mechanical behavior of the lung tissue (expressed by its constitutive equations) has considerable influence on the normal and pathological function of the lung. It determines the stress field in the tissue, thus affecting the impedence and energy consumption during breathing as well as the localization of certain lung diseases. The lung tissue has a complex mechanical response. It arises from the tissue’s structure—a cluster of a very large number of closely packed airsacks (alveoli) and air ducts. Each of the alveoli has a shape of irregular polyhedron. It is bounded by the alveolar wall membrane. In the present study, a stochastic approach to the tissue’s structure will be employed. The density distribution function of the membrane’s orientation in space is considered as the predominant structural parameter. Based on this model the present theory relates the behavior of both the alveolar membrane and that of its liquid interface to the tissue’s general constitutive properties. The resulting equations allow for anisotropic and visco-elastic effects. A protocol for material characterization along the present model is proposed as well. The methodology of the present theory is quite general and can be similarly used with other structural models of the lung tissue (e.g., models in which the effect of the alveolar ducts is included).
An Experimental Study of Velocity Distribution in a Human Lung Cast
Authors: Patra A. L. , Afify E. M.
Published: June 2009

A mechanical lung model with branching up to five generations, developed from an actual human lung, is used to study experimentally the velocity profiles in the trachea and the main branches. Three different flow rates representing light, medium, and heavy breathings have been simulated for both inhalation and exhalation. The velocity profiles, except for the one in the trachea in the frontal direction due to exhalation, are in good agreement with the velocity profiles in simplified models of published literature.
Parameter Sensitivity Analysis and Improvement of a Two-Layer Arterial Wall Model
Authors: von Maltzahn W. W.
Published: June 2009

The nonlinear two-layer arterial wall model introduced by von Maltzahn, et al. [11] is subjected to a rigorous parameter sensitivity and range of validity analysis. The model is based on the assumption that in large muscular conduit arteries the two mechanically significant layers are media and adventitia. Using curve-fitting techniques, the media is determined to be isotropic and the adventitia to be anisotropic. As a result of the range of validity analysis, the polynomial relationship for the energy density function of the media is changed to an exponential relationship. This leads to new coefficients for the polynomial of the adventitia. All coefficients have specific mechanical meanings. The parameter sensitivity analysis demonstrates convincingly that all model parameters are significantly important.
Tensile Fatigue Failure of Acrylic Bone Cement
Authors: Gates E. I. , Carter D. R. , Harris W. H.
Published: June 2009

Tensile fatigue tests of acrylic bone cement were conducted under strain control in a wet environment at 37°C. A constant strain rate of 0.02s−1 was used, resulting in physiologic loading frequencies. Comparison of the tensile fatigue data with the results of previous tension-compression fatigue tests indicates that fatigue failure is governed primarily by the maximum cyclic tensile strain. The compressive portion of the loading cycle has little effect on the number of cycles to failure. A new empirically derived equation is introduced to describe the influence of mean strain and strain amplitude on fatigue endurance. The results emphasize the critical role tensile strains may play in cement failure and loosening of total joint replacements.
Influence of Red Blood Cell Concentrations on the Measurement of Turbulence Using Hot-Film Anemometer
Authors: Sallam A. M. , Hwang N. H. C.
Published: June 2009

Measurement of local velocity fluctuations was made with an L-shaped conical hot-film probe in a submerged circular jet. The experiment was carried out in solutions of washed human red blood cells (RBC) in a phosphate buffer solution (PBS), at hematocrit concentrations (Ht percent) of 10, 19, 29, and 38 percent. The viscosity of the testing solutions was kept at 3.2 c.p. by adding proper amount of dextran. The experiment was conducted at Reynolds numbers (NR) 674, 963, 1255 and 1410, based on the jet exit velocity and exit diameter. Statistical analyses were performed on the recorded instantaneous velocity signals to obtain the root-mean-square (rms) values, the probability density functions (PDF) and the power spectral density functions (PSDF) of the signals. Within the range tested, we noticed an incidental rise in rms values at 19 to 29 Ht percent for NR = 963 similar to those reported earlier in the literature. Further analyses using PDF and PSDF, however, showed neither a trend nor any physical significance of this rise. Based on the analyses of both the PDF and the PSDF, we believe that the incidental rise in rms value can be partially attributed to the high spikes registered by the probe in a high RBC concentrations fluid flow. The bombardment of RBC on the probe thermal boundary layer may cause a characteristic change in the probe response to certain flow phenomenon, at least within the Reynolds number range used in this study. Additional theoretical and experimental information is needed to pin point the nature of this response. We thus suggest that the second and higher moments of the HFA signals obtained in a fluctuating flow field involving a liquid with relatively high contaminant concentrations cannot be interpreted as a simple flow phenomenon.
Modelling of a Composite Prosthesis for Quasi-Cylindrical Ligaments
Authors: Drouin G. , Dore´ R. , Thiry P. S. , Jean-Francois C.
Published: June 2009

A prosthesis for a cruciate ligament of the knee involves the problem of implanting a short and small spring for which the load-deformation response cannot be duplicated by any single man-made material. This work presents a model of the elastic behavior of a two material composite prosthesis made of high-strength fibers spirally wound around a soft elastic core. At each end of the core, the fibers are attached to a pulling device. Under a tension load, the fibers exert a pressure on the core which deforms radially, permitting the elongation of the prosthesis. This allows the achievement of large deformation while both the fibers and the core remain in the elastic domain. The high strength of the spring is provided by the high yield strength of the fibers. The results show the influence of the design variables on the deformation of the prosthesis.
Laboratory Evaluation of a Unified Theory for Simultaneous Multiple Axis Artificial Arm Control
Authors: Jerard R. B. , Jacobsen S. C.
Published: June 2009

This paper reports on the application of a “postulate-based” control method for multi-axis artificial arm control. This method uses shoulder muscle EMG’s as control sites, but, unlike previous techniques, the theory is the first that can be rigorously defined in terms of musculoskeletal anatomy, EMG muscle-force relationships, EMG transmission characteristics, muscle recruitment, limb dynamics and normal motion constraints. The control theory results in a deterministic, mathematically expressible set of controller equations, which use the vector of natural limb torques estimated by shoulder EMG signals and a “constraint” for input. The output of the controller equations is a vector of prosthetic torques to be applied to the artificial limb. We report on the implementation of the theory up to the point of laboratory feasibility trials of actual simultaneous above-elbow amputee control of elbow flexion and humeral rotation. Implementation of the theory required: 1) deviation of the controller equations from Newton’s dynamic equations of motion into controller form in conformity with the postulate theory; 2) development of a methodology for estimating natural musculoskeletal torques from EMG signals; 3) hardware and software for experimental testing with actual closed loop amputee control of the prosthesis; and 4) a methodology for evaluating the performance of the prosthesis relative to both alternative prosthetic systems and the natural arm. These tasks were completed and simultaneous multiple-axis control of a prosthetic arm was accomplished by both amputee and nonamputee subjects. Key questions of control compatibility, naturalness, stability, and performance evaluation relative to other prostheses and the natural arm were addressed. Various problems are discussed with the conclusion that this method, despite some difficulties, holds great promise as a practical rehabilitation tool.
An Apparatus for Measuring the Load-Displacement and Load-Dependent Kinematic Characteristics of Articulating Joints—Application to the Human Ankle Joint
Authors: Rastegar J. , Miller N. , Barmada R.
Published: June 2009

An apparatus is described which is capable of measuring the load-displacement characteristics as well as determining the loci of centers of rotation of articulating joints. The apparatus employs a floating head which permits the axis of rotation to coincide with the position of minimum joint resistance, thus eliminating non-physiological rotations at the joint. The coupled loads are also measured, thus providing an accurate description of the joint structural characteristics. Data taken from a freshly amputated human ankle joint is presented.
Changes in the Deformational Behavior of Human Hip Cartilage With Age
Authors: Armstrong C. G. , Bahrani A. S. , Gardner D. L.
Published: June 2009

The deformation occurring in the articular cartilage covering the human femoral head has been measured both when the femoral head is loaded in its natural acetabulum and when the cartilage is loaded with a small indentor. The results indicate that the material response is substantially different in these two situations. In the intact joint the cartilage deformation is substantially greater in older joints, but the response of cartilage to loading with an indentor does not change significantly with age. Theoretical elastic models of the cartilage behavior in these two situations were analyzed. For old cartilage which is idealized as an elastic material the increased deformation which is observed in the intact joint can be attributed to changes in Poisson’s ratio, though in the real material increased fluid flux under load is the more probable cause.
A Miniature Toposcopic Catheter Suitable for Small Diameter Tortuous Blood Vessels
Authors: Goldstein S. R. , Jones R. E. , Sipe J. J. , Doppman J. L. , Boretos J. W.
Published: June 2009

A miniature catheter suitable for clinical use based on the principle of the continuously everting tube has been developed and tested extensively in dogs. The 1-mm-dia flexible tube can advance up a narrow tortuous blood vessel 30 cm beyond the tip of the conventional catheter to which it is attached. A slippery hydromer coating combined with a U-shaped cross section enables the tube eversion to be accomplished at an acceptable operating pressure. The new system will provide access to previously inaccessible regions of the body, and has the potential for clinical use in embolizing selected vessels, providing highly localized chemotherapy, and sampling body fluids. The catheter can advance both with and against the blood flow in arteries and veins, and is awaiting clinical trials.
A Measurement of Proximal Femur Strain with Total Hip Arthroplasty
Authors: Crowninshield R. D. , Pedersen D. R. , Brand R. A.
Published: June 2009

Strain measurement was performed on loaded fresh human cadaveric proximal femurs before and after total hip femoral component implantation. Changes in the femurs’ strain state associated with loading through stainless steel and titanium femoral components were recorded. The role of proximal femur remodeling in femoral component loosening is discussed along with the likely effect of femoral component elastic modulus on the remodeling process.
Deformation of a Flexible Disk Bonded to an Elastic Half Space—Application to the Lung
Authors: Lai-Fook S. J. , Hajji M. A. , Wilson T. A.
Published: June 2009

An analysis is presented of the deformation of a homogeneous, isotropic, elastic half space subjected to a constant radial strain in a circular area on the boundary. Explicit analytic expressions for the normal and radial displacements and the shear stress on the boundary are used to interpret experiments performed on inflated pig lungs. The boundary strain was induced by inflating or deflating the lung after bonding a flexible disk to the lung surface. The prediction that the surface bulges outward for positive boundary strain and inward for negative strain was observed in the experiments. Poisson’s ratio at two transpulmonary pressures was measured, by use of the normal displacement equation evaluated at the surface. A direct estimate of Poisson’s ratio was possible because the normal displacement of the surface depended uniquely on the compressibility of the material. Qualitative comparisons between theory and experiment support the use of continuum analyses in evaluating the behavior of the lung parenchyma when subjected to small local distortions.
Hemodynamic Measurements in Human Arterial Casts, and Their Correlation With Histology and Luminal Area
Authors: Friedman M. H. , Bargeron C. B. , Hutchins G. M. , Mark F. F. , Deters O. J.
Published: June 2009

A new approach is presented for studying the vascular response to hemodynamic stress. A laser doppler anemometer is used to make velocity measurements very near the walls of human arterial casts; these measurements are then correlated with the histology of the artery from which the cast was made. Several illustrative results are given which suggest that the velocity profiles along the outer walls of aortic bifurcations may be significantly determined by the longitudinal variation of cross-sectional area. The shapes of these profiles were qualitatively different for each cast studied. In one specimen, the location of initial lipid deposits appeared to correlate with flow acceleration.
Derivation of Myocardial Fiber Stiffness Equation Based on Theory of Laminated Composite
Authors: Pao Y. C. , Nagendra G. K. , Padiyar R. , Ritman E. L.
Published: June 2009

The constitutive equation with stress-dependent coefficients for laminated composite is derived and employed for iterative determination of myocardial fiber’s stiffness equation Ef = Kσf + C from myocardial strip’s stiffness equation Es = Ksσs + Cs. The strip’s stiffness constants Ks and Cs are estimated by the least-square curve fitting of the stress-strain data experimentally obtained from uniaxially stretching of strips of left ventricular heart wall excised from seven canine hearts. The values of K and C computed at selected fiber orientations across the thickness of the strip and using three, five, and ten-layer approximations are reported.
Fiber Optic Microfluorimetry for Acute and Chronic In-Vivo Animal Studies
Authors: Goldstein S. R. , Bonner R. F. , Dedrick R. L. , Grantham F. H. , Gullino P. M. , Gibson C. C. , McGuire D. A.
Published: June 2009

Highly localized long-term measurements of tumor transport properties are performed with pairs of adjacent, parallel single-strand optic fibers embedded in a laboratory animal. External illumination and light sensing equipment detect local concentration of a fluorescent indicator initially injected into the venous system. Under appropriate conditions, blood flow per unit volume, capillary permeability, and uptake of fluorescent drugs can be determined from the fluorescence time history. The observation volume has a characteristic dimension on the order of 0.5 mm. Chronic tests in 20 animals monitored for 1–2 weeks have demonstrated that the technique is practical, the tumor histology is acceptable, and the measured local tissue uptake is comparable to average values in the literature. The technique is also suitable for acute experiments using a miniature fiber optic needle probe.
Why should clinicians understand epidemiology?
Authors: McAllister D , Wild S
Published: June 2009

This article summarises the importance of epidemiology to clinicians and aims to show how an understanding of epidemiological concepts can make an important contribution to optimum clinical practice in its broadest sense. Epidemiological principles can be applied to clinical practice in interpreting the results of diagnostic tests, assessing and communicating risk and prognosis, and in identifying appropriate treatment for individual patients. They are also of value to clinicians involved in planning, monitoring and improving services, teaching medical students and postgraduates, critically appraising medical literature, and undertaking or supervising research.
Chronic atrial fibrillation: a systematic review of medical heart rate control management
Authors: Nikolaidou T , Channer K S
Published: June 2009

Objective

Recent guidelines by the National Institute for Health and Clinical Excellence (NICE) and the American College of Cardiology/American Heart Association/European Society of Cardiology (ACC/AHA/ESC) on rate control management for chronic atrial fibrillation have relegated digoxin to second line treatment, recommending instead the use of β-blockers or rate limiting calcium antagonists as first line treatment. The objective of this review is to assess the efficacy of these drugs in controlling heart rate, and in improving symptoms and exercise tolerance.

Data sources

We electronically searched the Medline, Embase and Cochrane databases, hand searched journals and relevant bibliographies for articles.

Selection of studies

We included all study designs evaluating or comparing oral digoxin, β-blockers and calcium antagonists, alone or in combination, for rate control in chronic atrial fibrillation. 46 studies satisfied our inclusion and quality criteria.

Results

Published studies are small and too heterogeneous to be quantitatively combined. Descriptive synthesis of the data shows little evidence that monotherapy with β-blockers or calcium antagonists improves symptoms or exercise capacity in patients with chronic atrial fibrillation. Instead it is associated with dose related side effects.

Conclusion

Based on the limited data available, we conclude that the combination of digoxin with either a β-blocker or calcium antagonist should be first line management in patients with chronic atrial fibrillation.
Role of cementoplasty in the management of compression vertebral body fractures
Authors: Hamady M , Sheard S
Published: June 2009

Osteoporotic vertebral compression fractures cause pain, reduced mobility and consequently poor quality of life, and as such have a significant impact on health resources. Their prevalence can be expected to increase with the ageing population. Until recently, only conservative management has been available to alleviate pain and improve mobility. Originally developed in the 1980s to treat vascular malformation in the spine, vertebroplasty offers an interventional method for improving symptoms of vertebral compression fractures. Percutaneous vertebroplasty involves stabilisation of the fractured vertebral body using cement which is introduced via a needle under image guidance. Kyphoplasty is a more recent development in which a balloon is inflated within the fractured vertebral body in order to correct any loss of height before cement stabilisation. There is a lack of major randomised controlled trials on either procedure at present, but evidence of their safety and efficacy is increasing, suggesting that both are more effective than conservative management, with low risk of complications.
Knowledge and attitudes of breast self examination in a group of women in Shiraz, southern Iran
Authors: Simi A , Yadollahie M , Habibzadeh F
Published: June 2009

Background

Breast cancer is the most common cause of cancer related deaths among women worldwide. The disease in women occurs at a younger age in Iran than in western communities.

Objective

To determine the practice of breast self examination (BSE) among 25–54-year-old women in Shiraz, southern Iran.

Methods

Using a stratified convenient sampling method, a total of 300 women aged 25–54 years who attended our health care centre between September 2006 and May 2007 were invited for an interview on BSE. All invited women accepted and were interviewed. The questions included demographic information, level of education, whether the participant performed BSE and, if yes, how and when. They were also asked about their source of information.

Results

The median (interquartile range (IQR)) age of participants was 38.5 (14) years. Of the 300 studied women, 283 (94.3%) were married; 160 (53.3%) performed BSE—9 (5.6%) of whom did BSE using a correct method and at an appropriate time. Of 140 non-performers, 74 (52.9%) did not know how to do BSE; the remaining women did not do BSE for fear of being found positive for cancer or did not care about it. Those who performed BSE learned it from medical personnel (n = 72, 49.4%), their relatives, and TV, radio, books, journals and pamphlets. Of those who performed BSE, 9 (5.6%) found an abnormal examination; 6 (3.8%) were found positive after further evaluation. The likelihood of performing BSE was not associated with educational level, marital status, age of participant, or how the participant learned about BSE.

Conclusions

Considering that 46.7% of participants did not perform BSE, and that almost all of those who did perform BSE did it incorrectly—and taking into account that a lack of knowledge on how to perform BSE was the main reason why most non-performers did not examine themselves—establishing educational programmes to teach women at risk may help in the early diagnosis of breast cancer.
Drug induced parkinsonism: a common cause of parkinsonism in older people
Authors: Thanvi B , Treadwell S
Published: June 2009

Drug induced parkinsonism is the second most common cause of parkinsonism in older people after idiopathic Parkinson’s disease (PD). Risk factors for developing drug induced parkinsonism include: older age; female gender; dose and duration of treatment; type of agent used; cognitive impairment; acquired immunodeficiency syndrome (AIDS); tardive dyskinesia; and pre-existing extrapyramidal disorder. In most patients parkinsonism is reversible upon stopping the offending drug, though it may take several months to resolve fully and in some patients it may even persist. In this case, one needs to consider the possibility of PD which has been unmasked by the offending drug, and treatment with dopaminergic agents may be warranted. Drug induced parkinsonism adversely affects the quality of life in older patients and is potentially reversible, highlighting the importance of early recognition of this condition. This article discusses the drugs implicated, as well as the epidemiology, pathophysiology, clinical features, and management of drug induced parkinsonism.
Natriuretic peptides and heart failure in the patient with chronic kidney disease: a review of current evidence
Authors: Dhar S , Pressman G S , Subramanian S , Kaul S , Gollamudi S , Bloom E J , Figueredo V M
Published: June 2009

Natriuretic peptides such as brain natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP) are commonly used in the diagnosis and evaluation of heart failure. However, their utility in patients with chronic kidney disease (CKD) is less clear as renal dysfunction itself can be associated with elevated concentrations of these biomarkers. Given the high prevalence of left ventricular hypertrophy and left ventricular systolic dysfunction in patients with CKD, diagnosis or exclusion of heart failure becomes important in this population. Most studies to date indicate that upward adjustment of diagnostic cut points preserves the usefulness of both BNP and NT-proBNP in the CKD patient, with similar clinical performance of each biomarker. We review the role of natriuretic peptide in heart failure in the setting of chronic renal disease.
Chronic kidney disease and bisphosphonate treatment: are prescribing guidelines unnecessarily restrictive?
Authors: Courtney A E , Maxwell A P
Published: June 2009

The prevalence of both osteoporosis and chronic kidney disease (CKD) increases with advancing age. Bisphosphonates are effective in the prevention and treatment of osteoporosis but current recommendations limit their use in patients with renal impairment because of concern regarding the safety profile of these agents in the setting of reduced renal function. The appropriateness of bisphosphonate treatment for patients with CKD is also in question since CKD is independently associated with a variety of skeletal abnormalities, collectively termed renal osteodystrophy, including pre-existing low bone turnover. The evidence to support the current prescribing restrictions is not robust and there are some data to suggest both that bisphosphonate treatment reduces fracture risk without an increase in adverse events in patients with CKD, and that in clinical practice there is underutilisation of this treatment in early CKD. Appropriate prospective trial data with clinically important end points in CKD patients is awaited.
Mountain mortality: a review of deaths that occur during recreational activities in the mountains
Authors: Windsor J S , Firth P G , Grocott M P , Rodway G W , Montgomery H E
Published: June 2009

The growing popularity of activities such as hiking, climbing, skiing and snowboarding has ensured that the number of visitors to mountain environments continues to increase. Since such areas place enormous physical demands on individuals, it is inevitable that deaths will occur. Differences in the activities, conditions and methods of calculation make meaningful mortality rates difficult to obtain. However, it is clear that the mortality rate for some mountain activities is comparable to hang gliding, parachuting, boxing and other pastimes that are traditionally viewed as dangerous. Deaths in the mountains are most commonly due to trauma, high altitude illness, cold injury, avalanche burial and sudden cardiac death. This review describes the mortality rates of those who undertake recreational activities in the mountains and examines the aetiology that lies behind them.
MELTING OF THE GLASSLIKE 19-ATOM GOLD CLUSTER
Authors: REN SHI-WEI
Published: June 2009

In this paper, the melting behaviors of the glasslike cluster Au 19 are calculated and analyzed by using standard microcanonical molecular-dynamics simulations. The calculated results show a multi-step melting process. The first stage involves the majority of the surface atoms (14 atoms). An interesting phenomenon is that the minority of the surface atoms (4 atoms) are still in a solid-like state. The second stage involves all of the surface atoms. But there are two sites where the atoms stay for a relatively long time. The third stage corresponds to the frequent isomerizations involving all the surface atoms. The final stage consists of isomerization transitions involving all of the atoms, including the central atom of the cluster. The unique melting processes lead to the unique features of the caloric curve, the root-mean-square bond-length fluctuation and the heat capacity of the glasslike Au 19.
CONSENSUS FORMATION IN WEIGHTED SCALE-FREE NETWORKS
Authors: HU KE , TANG YI
Published: June 2009

We develop a consensus model for studying opinion dynamics in weighted networks and investigate the effects of both the distribution of weights and the correlations between weight and degree on dynamical behaviors of opinion formation. Our results suggest that a global consensus in the weighted networks to reach is more difficult than that in unweighted network, and strongly depends on the heterogeneity of connection strengths. In addition, in the weighted network with very large heterogeneity of connection strengths, only single macroscopic opinion cluster can be formed, which differs from the behavior in the unweighted network where the next-largest macroscopic opinion cluster may exist.
EVOLUTIONARY GAMES IN MULTI-AGENT SYSTEMS OF WEIGHTED SOCIAL NETWORKS
Authors: DU WEN-BO , CAO XIAN-BIN , ZHENG HAO-RAN , ZHOU HONG , HU MAO-BIN
Published: June 2009

Much empirical evidence has shown realistic networks are weighted. Compared with those on unweighted networks, the dynamics on weighted network often exhibit distinctly different phenomena. In this paper, we investigate the evolutionary game dynamics (prisoner's dilemma game and snowdrift game) on a weighted social network consisted of rational agents and focus on the evolution of cooperation in the system. Simulation results show that the cooperation level is strongly affected by the weighted nature of the network. Moreover, the variation of time series has also been investigated. Our work may be helpful in understanding the cooperative behavior in the social systems.
COMPARING ENTROPIC AND MULTIPLE RELAXATION TIMES LATTICE BOLTZMANN METHODS FOR BLOOD FLOW SIMULATIONS
Authors: GEERDINK JOOST B. W. , HOEKSTRA ALFONS G.
Published: June 2009

We compare the Lattice BGK, the Multiple Relaxation Times and the Entropic Lattice Boltzmann Methods for time harmonic flows. We measure the stability, speed and accuracy of the three models for Reynolds and Womersley numbers that are representative for human arteries.

The Lattice BGK shows predictable stability and is the fastest method in terms of lattice node updates per second. The Multiple Relaxation Times LBM shows erratic stability which depends strongly on the relaxation times set chosen and is slightly slower. The Entropic LBM gives the best stability at the price of fewer lattice node updates per second.

A parameter constraint optimization technique is used to determine which is the fastest model given a certain preset accuracy. It is found that the Lattice BGK performs best at most arterial flows, except for the high Reynolds number flow in the aorta, where the Entropic LBM is the fastest method due to its better stability. However we also conclude that the Entropic LBM with velocity/pressure inlet/outlet conditions shows much worse performance.
A MODEL FOR SOLVENT MEDIATED INTERACTIONS BETWEEN MOLECULES AND SURFACES
Authors: OCHOA JUAN G. DIAZ
Published: June 2009

This work introduces a novel coarse-grained model representing the dynamics of polar molecules that adsorb on a substrate in the presence of a solvent. The motivation of the model is to avoid the explicit representation of the solvent. Instead, the solvent-mediated interaction is indirectly represented using a fluctuating energy landscape. The dynamics, on which this model is based, are similar to the dynamics in game theory. In particular, the strategy of an agent in a game is similar to the modification of the free energy barrier between the molecule and the substrate induced by other companion molecules. The aim of this method is to show how the interplay between solvents and companion molecules can imply a modification in the adsorption energy of molecules, and how this modification can buffer the adsorption of specific molecules on surfaces. The results, and their implications in the molecular recognition of surfaces, are discussed.
PARALLELIZATION OF REVERSIBLE RIPPLE-CARRY ADDERS
Authors: THOMSEN MICHAEL KIRKEDAL , AXELSEN HOLGER BOCK
Published: June 2009

The design of fast arithmetic logic circuits is an important research topic for reversible and quantum computing. A special challenge in this setting is the computation of standard arithmetical functions without the generation of garbage.

Here, we present a novel parallelization scheme wherein m parallel k-bit reversible ripple-carry adders are combined to form a reversible mk-bit ripple-block carry adder with logic depth [Formula: see text] for a minimal logic depth [Formula: see text], thus improving on the mk-bit ripple-carry adder logic depth [Formula: see text]. The underlying mechanisms of the parallelization scheme are formally proven correct. We also show designs for garbage-less reversible comparison circuits.

We compare the circuit costs of the resulting ripple-block carry adder with known optimized reversible ripple-carry adders in measures of circuit delay, width, gate, transistor count, and relative power efficiency, and find that the parallelized adder offers significant speedups at realistic word sizes with modest parallelization overhead.
A NEW UNIVERSAL CELLULAR AUTOMATON ON THE PENTAGRID
Authors: MARGENSTERN MAURICE , SONG YU
Published: June 2009

In this paper, we significantly improve a result of the first author, published in an issue of Theoretical Computer Science in 2003. In this paper, the authors showed the existence of a weakly universal cellular automaton on the pentagrid with 22 states. The simulation used a railway circuit which simulates a register machine. In the present paper, using the same simulation tool, we lower the number of states for a weakly universal cellular automaton down to 9.
HOW FAR IS IT TO THE NEXT RECURRENT CONFIGURATION? AN NP-COMPLETE PROBLEM IN THE SANDPILE MODEL
Authors: SCHULZ MATTHIAS
Published: June 2009

We take a look at transient configurations of the Abelian Sandpile Model (ASM). If we add enough grains on the "right" sites to this configuration we get a recurrent configuration of the ASM. In this paper we show that it is NP-complete to decide for a transient configuration c on a grid of size m × m and a natural number k if it is possible to add k grains of sand to c such that we get a recurrent configuration. We show this by reducing the problem of deciding whether a given planar cubic graph of size n ∈ Θ(m) has a vertex cover, which is NP-complete, to this problem.
CELLULAR AUTOMATA ENCRYPTION: the reverse algorithm, Z-parameter and chain-rules
Authors: WUENSCHE ANDREW
Published: June 2009

Chain-rules are maximally chaotic cellular automata (CA) rules that can be constructed at random to provide a huge number of encryption keys – where the CA is run backwards to encrypt, forwards to decrypt. The methods are based on the 1D CA reverse algorithm for directly finding pre-images, and the resulting Z-parameter, and rely on the essential property that chain-rules have minimal in-degree in their basins of attraction, usually an in-degree of just one for larger systems.
A FAMILY OF SMALLEST SYMMETRICAL FOUR-STATE FIRING SQUAD SYNCHRONIZATION PROTOCOLS FOR RING ARRAYS
Authors: UMEO HIROSHI , KAMIKAWA NAOKI , YUNÈS JEAN-BAPTISTE
Published: June 2009

An existence or non-existence of five-state firing squad synchronization protocol has been a longstanding and famous open problem for a long time. In this paper, we answer partially to this problem by proposing a family of smallest four-state firing squad synchronization protocols that can synchronize any one-dimensional ring cellular arrays of length n = 2k for any positive integer k. The number four is the smallest one in the class of synchronization protocols proposed so far.
Exploiting ILP, TLP, and DLP to Improve Multi-Core Performance of One-Sided Jacobi SVD
Authors: Soliman Mostafa I.
Published: June 2009

This paper shows how the performance of singular value decomposition (SVD) is enhanced through the exploitation of ILP, TLP, and DLP on Intel multi-core processors using superscalar execution, multi-threading computation, and streaming SIMD extensions, respectively. To facilitate the exploitation of TLP on multiple execution cores, the well-known cyclic one-sided Jacobi algorithm is restructured to work in parallel. On two dual-core Intel Xeon processors with hyper-threading technology running at 3.0 GHz, our results show that the multi-threaded implementation of one-sided Jacobi SVD gives about four times faster than the single-threaded superscalar implementation. Furthermore, the multi-threaded SIMD implementation speeds up the execution of single-threaded one-sided Jacobi by a factor of 10, which is close to the ideal speedup. On a reasonable large matrix size fitted in the L2 cache, our results show a performance of 11 GFLOPS (double-precision) is achieved on the target system through the exploitation of ILP, TLP, and DLP as well as memory hierarchy.
THERMODYNAMICS AND EXTRA DIMENSIONS
Authors: MAGPANTAY JOSE A.
Published: June 2009

We consider the effects of extra dimensions on the thermodynamics of classical ideal gases, Bose–Einstein gases and Fermi–Dirac gas. Assuming a q-dimensional torus for the extra dimensions, we compute the thermodynamic functions such as the equation of state, the average energy and the specific heat at constant volume for the three systems. We show that the corrections due to the extra dimensions are small, proportional to [Formula: see text].
ENTANGLEMENT GENERATION WITH GEOMETRIC OPERATIONS IN CAVITY QED
Authors: ZHANG GANG , DONG PING , CAO ZHUO-LIANG
Published: June 2009

We propose a one-step cluster state generation scheme via atomic cavity QED. The current scheme is insensitive to the cavity mode thermal state as well as the atomic spontaneous emission since the gate operations are independent of the cavity mode states and laser power is sufficiently weak. In addition, the needed operation is of geometric nature, so it is robust against random operation errors.
FAILURE ASSESSMENT OF UHTC PLATE UNDER ELEVATED TEMPERATURE
Authors: ZENG TAO , ZHOU FEI-FEI , FANG DAI-NING , YAN SHI , GUO YING
Published: June 2009

In the present study, a theoretical model is presented to assess the failure temperature for ultra-high temperature ceramics (UHTCs). Unlike traditional thermal shock theory, the parameters, such as thermal expansion coefficient and Young's modulus, are considered a function of temperature in the present model. The oxide film of UHTCs is also believed to grow under high temperature. Considering two kinds of conditions, the critical elevated temperature for delamination is calculated using Griffith's theory. By establishing the relation between temperature and the mechanical properties of UHTCs, it is found that the failure behavior of UHTCs is strongly affected by the oxide film thickness, initial temperature and the heating rate.
NOVEL ROBUST DELAY-DEPENDENT CRITERION FOR ABSOLUTE STABILITY OF LUR'E SYSTEMS OF NEUTRAL TYPE
Authors: LEE S. M. , KWON O. M. , PARK JU H.
Published: June 2009

This letter considers uncertain Lur'e systems of neutral type with sector and slope restrictions. By constructing a new Lyapunov functional, a novel delay-dependent criterion for absolute stability is derived in terms of linear matrix inequalities (LMIs). Two numerical examples are illustrated to show the effectiveness of the proposed method.
DYNAMICAL PROPERTIES OF AN ANTI-TUMOR CELL GROWTH SYSTEM IN THE PRESENCE OF DELAY AND CORRELATED NOISES
Authors: ZENG CHUN-HUA , XIE CHONG-WEI
Published: June 2009

We study dynamical properties of an anti-tumor cell growth system in the presence of time delay and correlations between multiplicative and additive white noise. Using the small time delay approximation, the Novikov theorem and Fox approach, the stationary probability distribution (SPD) is obtained. Based on the SPD, the expressions of the normalized correlation function C(s) and the associated relaxation time Tc are derived by means of Stratonovich decoupling ansatz. Based on numerical computations, we find the following: (i) The SPD exhibits one-peak → two-peaks → one-peak phase transitions as the correlation intensity λ varies. (ii) The relaxation time Tc exhibits a one-peak structure for negatively correlated noise (λ<0), however for positively correlated noise (λ>0), the relaxation time Tc decreases monotonously. (iii) The effects of the delay time τ on Tc and C(s) are entirely the same for λ<0 and for λ>0, i.e. τ enhances the fluctuation decay of the population of tumor cells.
CHARGE TRANSFER FROM MONOLAYERED CdSe/ZnS QUANTUM DOTS TO C60
Authors: XIAO SI , SU XIONG-RUI , PENG XIAO-NIU , YU XUE-FENG
Published: June 2009

The interaction between C 60 and quantum dots (QDs) has attracted much attention recently due to its potential applications in solar cells, for example, as a promising renewable energy source. In this paper, monolayer self-assembled CdSe/ZnS core/shell QDs films were prepared and drop-coated with different amounts of C 60. A significant photoluminescence quenching and an emission lifetime reduction were observed in the QDs- C 60 composite films, and the quenching efficiency was increased with the increasing of the C 60 content. Together with the reduced emission lifetime, the results here provide direct evidence for the charge transfer process in the QDs- C 60 system.
A VERSATILE APPROACH FOR THE SYNTHESIS OF ALUMINUM OXIDE NANORODS BASED ON A SIMPLE REACTION
Authors: SHAH M. A.
Published: June 2009

Aluminum oxide (α -Al 2 O 3) nanorods have been successfully synthesized by a simple reaction of aluminum powder with water without any additives/organics at 100°C. This is the first report for the synthesis of aluminum oxide nanorods where water has been used as solvent as well as a source of oxygen. The diameters of nanorods are relatively uniform, ranging from 40–60 nm with length of several micrometers. A plausible mechanism is proposed for the formation of these nanorods and is expected that this synthetic technique can be extended to obtain other metal oxides. Photoluminescence measurements reveal a blue luminescence band with two peaks at 310 and 420 nm, which could be attributed to F + centers. The reported method is new, economical, fast and free of pollution, which will make it suitable for large scale production.
SUBSPACES VERSUS SUBMANIFOLDS: A COMPARATIVE STUDY IN SMALL SAMPLE SIZE PROBLEM
Authors: HUANG HONG , LI JIANWEI , FENG HAILIANG
Published: June 2009

Automatic face recognition is a challenging problem in the biometrics area, where the dimension of the sample space is typically larger than the number of samples in the training set and consequently the so-called small sample size problem exists. Recently, neuroscientists emphasized the manifold ways of perception, and showed the face images may reside on a nonlinear submanifold hidden in the image space. Many manifold learning methods, such as Isometric feature mapping, Locally Linear Embedding, and Locally Linear Coordination are proposed. These methods achieved the submanifold by collectively analyzing the overlapped local neighborhoods and all claimed to be superior to such subspace methods as Eigenfaces and Fisherfaces in terms of classification accuracy. However, in literature, no systematic comparative study for face recognition is performed among them. In this paper, we carry out a comparative study in face recognition among them, and the study considers theoretical aspects as well as simulations performed using CMU PIE and FERET face databases.
FEATURE EXTRACTION THROUGH CROSS-PHASE CONGRUENCY FOR FACIAL EXPRESSION ANALYSIS
Authors: BUCIU IOAN , NAFORNITA IOAN
Published: June 2009

Human face analysis has attracted a large number of researchers from various fields, such as computer vision, image processing, neurophysiology or psychology. One of the particular aspects of human face analysis is encompassed by facial expression recognition task. A novel method based on phase congruency for extracting the facial features used in the facial expression classification procedure is developed. Considering a set of image samples comprising humans expressing various expressions, this new approach computes the phase congruency map between the samples. The analysis is performed in the frequency space where the similarity (or dissimilarity) between sample phases is measured to form discriminant features. The experiments were run using samples from two facial expression databases. To assess the method's performance, the technique is compared to the state-of-the art techniques utilized for classifying facial expressions, such as Principal Component Analysis (PCA), Independent Component Analysis (ICA), Linear Discriminant Analysis (LDA), and Gabor jets. The features extracted by the aforementioned techniques are further classified using two classifiers: a distance-based classifier and a Support Vector Machine-based classifier. Experiments reveal superior facial expression recognition performance for the proposed approach with respect to other techniques.