bluuebunny/crossref_metadata_2025 huggingface dataset:
Basic general concepts in the network analysis
Authors: Boja Nicolae
Published: March 2008

This survey is concerned oneself with the study of those types of material networks which can be met both in civil engineering and also in electrotechnics, in mechanics, or in hydrotechnics, and of which behavior lead to linear problems, solvable by means of Finite Element Method and adequate algorithms. Here, it is presented a unitary theory of networks met in the domains mentioned above and this one is illustrated with examples for the structural networks in civil engineering, electric circuits, and water supply networks, but also planar or spatial mechanisms can be comprised in this theory. The attention is focused to make evident the essential proper- ties and concepts in the network analysis, which differentiate the networks under force from other types of material networks. To such a network a planar, connected, and directed or undirected graph is associated, and with some vector fields on the vertex set this graph is endowed. .
Optimal synthesis of a four-bar linkage by method of controlled deviation
Authors: Bulatovic Radovan , Djordjevic Stevan
Published: March 2008

This paper considers optimal synthesis of a four-bar linkage by method of controlled deviations. The advantage of this approximate method is that it allows control of motion of the coupler in the four-bar linkage so that the path of the coupler is in the prescribed environment around the given path on the segment observed. The Hooke-Jeeves?s optimization algorithm has been used in the optimization process. Calculation expressions are not used as the method of direct searching, i.e. individual comparison of the calculated value of the objective function is made in each iteration and the moving is done in the direction of decreasing the value of the objective function. This algorithm does not depend on the initial selection of the projected variables. All this is illustrated on an example of synthesis of a four-bar linkage whose coupler point traces a straight line, i.e. passes through sixteen prescribed points lying on one straight line. .
Influence of structural backlash and friction in command system on the aircraft flutter
Authors: Maricic N.
Published: March 2008

Experience has shown that aircraft structures are generally affected by structural nonlinearities. The focus in this paper is concentrated on backlash and friction described in hysteresis loop of the classical aircraft command systems and their influence on flutter of aircraft. Based on AGARD No. 665 in paper is done nonlinear flutter velocity analysis in function of backlash and friction in the classical command system of aircraft. Unsteady aerodynamic forces are calculated based on well known Doublet- Lattice Method (DLM). Structural input data are taken from AGARD No. 665. Flutter eigenvalues are obtained by modified k-method. The flutter model of nonlinear aircraft structure is developed on base of harmonic linearization. The aim of paper is to achieve useful and relatively reliable tool for critical observations on different recommendations given in the various airworthiness regulations for nonlinear characteristics of hysteresis loops in the classical command systems of aircrafts. .
Particle dynamics simulations of expansion of a cylindrical cavity within an infinite brittle medium
Authors: Mastilovic Sreten , Krajcinovic Dusan
Published: March 2008

The present review focuses on the plane strain problem of high strain rate expansion of a cylindrical cavity within an infinite brittle material with random microstructure. The material is represented by an ensemble of "continuum particles" forming a two-dimensional geometrically and structurally disordered lattice. The proposed model includes the aleatory variability and epistemic uncertainty of the process. The dynamic particle simulations are performed at seven different cavity expansion rates. The resulting damage evolution process is non-stationary, non-local, and non-equilibrium. This problem, therefore, belongs to the class of phenomena for which the traditional continuum models are not well suited, and detailed experimental data are either difficult to get or not available at all. The present study explores the potential role of the particle dynamics in addressing these problems. .
Digital practical tracking: Algorithms with vector settling time
Authors: Stojcic Mihajlo
Published: March 2008

In this paper nonlinear stationary digital system with separated control is treated. The new definitions of practical tracking with vector settling time are presented. Furthermore, new criteria and control algorithms which ensure digital practical tracking with vector settling time are given and proven. The results are simulated on an example.
Limit load solution for mismatched welded plate and pressure vessel with a surface crack
Authors: Argoub Emhamed , Sedmak Aleksandar , Sedmak Stojan , Adziev Gorgi
Published: March 2008

Fracture behavior of a structure having a crack in the middle of a weld is influenced by the mechanical properties of the welded joint constituents (weld metal, base metal, heat-affected-zone) and their geometry. Therefore, defect assessment procedures have been developed in order to take into account all those affecting parameters. One of the key point for all those defect assessment procedures is to have limit load solutions of the mismatch structure. Such limit load solutions have been obtained by using 3D finite element solutions for different configurations such as plate with surface crack in tension or pressure vessel with axial external surface crack exposed to internal pressure, since those limit load have been obtained for non-hardening material exponent.
Modeling of fragmentation of rapidly expanding cylinders
Authors: Elek Predrag , Jaramaz Slobodan
Published: March 2008

The paper considers fragmentation process of high-explosive projectile casings, i.e. rapidly expanding cylinders loaded by extreme internal pressure generated by detonation of explosives. The classical, physically based, Mott model of the ring fragmentation is examined and the adequate computer program is realized. The fragment size (or mass) distribution is analyzed and the average fragment size is related to the characteristics of expansion and the casing material properties. The influence of the fragmentation process parameters on the nature of fragment length distribution is analyzed. The theoretical distributions are compared with experimental data and good correspondence is obtained.
On injection-ejection fluid influence through different accelerating porous surfaces on unsteady 2d incompressible boundary layer characteristics
Authors: Ivanovic Decan , Ivanovic Vladan
Published: March 2008

Through the porous contour in perpendicular direction, the fluid of the same properties as incompressible fluid in basic flow, has been injected or ejected with velocity who is a function of the contour longitudinal coordinate and time. The corresponding equations of unsteady boundary layer, by introducing the appropriate variable transformations, momentum and energy equations and two similarity parameters sets, are transformed into generalized form. These parameters are expressing the influence of the outer flow velocity, the injection or ejection velocity and the flow history in boundary layer, on the boundary layer characteristics. Obtained generalized solutions are used to calculate the distributions of velocity, and shear stress in laminar-turbulent transition of unsteady incompressible boundary layer on different porous contours: circular cylinder, thin elliptical cylinder and aerofoil, whose centers velocities changes in time as a degree functions. The ejection of fluid postpones the boundary layer separation, i.e. laminar-turbulent transition, and vice versa the injection of fluid favors the separation. Boundary layer characteristics are found directly, no further numerical integration of momentum equation.
The crack kinking out of an interface
Authors: Veljkovic Jelena
Published: March 2008

Kinking of a plane strain crack out of an interface between the two dissimilar isotropic elastic materials is analyzed. Analysis is focused on the initiation of kinking and thus the segment of the crack leaving the interface is imagined to be short compared to the segment in the interface. The analysis provides the stress intensity factors and energy release rate of the kinked cracks in terms of the corresponding quantities for the interfacial crack. The energy release rate is enhanced if the crack heads into the more compliant material and is diminished if the crack kinks into the stiff material.
Radiation effects on flow past an impulsively started vertical plate with variable temperature and mass flux
Authors: Muthucumaraswamy R. , Vijayalakshmi A.
Published: March 2008

An analysis is performed to study the thermal radiation effects on unsteady free convective flow over a moving vertical plate in the presence of variable temperature and uniform mass flux. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The temperature is raised linearly with time and the concentration level near the plate are raised linearly with time. The dimensionless governing equations are solved using the Laplace transform technique. The velocity and skinfriction are studied for different parameters like the radiation parameter, Schmidt number, thermal Grashof number, mass Grashof number and time. It is observed that the velocity increases with decreasing radiation parameter.
A paradox of non-monotonicity in stability of pipes conveying fluid
Authors: Elishakoff I. , Vittori P.
Published: March 2008

The paradoxical result of the non-monotonous relationship between the critical speed of the fluid that is conveyed in the elastic pipe, and the mass ratio was reported first some four decades ago. Since then this result was reproduced in numerous books and articles. In this study the paradox is revisited. It appears that it is a numerical artifact; instead of non-monotonicity there are jumps.
The interaction of thermal radiation on vertical oscillating plate with variable temperature and mass diffusion
Authors: Muthucumaraswamy R.
Published: March 2008

Thermal radiation effects on unsteady free convective flow of a viscous incompressible flow past an infinite vertical oscillating plate with variable temperature and mass diffusion has been studied. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The plate temperature is raised linearly with respect to time and the concentration level near the plate is also raised linearly with respect to time. An exact solution to the dimensionless governing equations has been obtained by the Laplace transform method, when the plate is oscillating harmonically in its own plane. The effects of velocity, temperature and concentration are studied for different parameters like phase angle, radiation parameter, Schmidt number, thermal Grashof number, mass Grashof number and time are studied. It is observed that the velocity increases with decreasing phase angle ?t. .
Effects of chemical reaction, heat and mass transfer on boundary layer flow over a porous wedge with heat radiation in the presence of suction or injection
Authors: Kandasamy R. , Abd Wahid , Khamis Azme
Published: March 2008

The effect of chemical reaction, heat and mass transfer on boundary layer flow over a porous wedge with heat radiation has been studied in the presence of suction or injection. An approximate numerical solution for the steady laminar boundary-layer flow over a wall of the wedge in the presence of species concentration and mass diffusion has been obtained by solving the governing equations using numerical technique. The fluid is assumed to be viscous and incompressible. Numerical calculations are carried out for different values of dimensionless parameters and an analysis of the results obtained shows that the flow field is influenced appreciably by the chemical reaction, the buoyancy ratio between species and thermal diffusion and suction/injection at wall surface. Effects of these major parameters on the transport behaviors are investigated methodically and typical results are illustrated to reveal the tendency of the solutions. Representative results are presented for the velocity, temperature, and concentration distributions, as well as the skin friction, rate of heat transfer and mass transfer. Comparisons with previously published works are performed and excellent agreement between the results is obtained. .
A polynomial approach to determine stress in an elastic body of circular section indented by conformable contact
Authors: Hinojosa-Torres J. , Hernandez-Anda J.L.
Published: March 2008

A polynomial of degree greater than two that describes the indenter concavity shape is proposed. From the proposed polynomial, the gradient of the displacement is derived and combined with that one determined by Timoshenko and Goodier to obtain the polynomial distribution of the pressure in the cross direction of wire. By using the polynomial pressure in the "stress function" proposed by Flamant, a set of equations serving to know the stresses state in the wire section is obtained. To extend the analysis to two opposite indenters, all contributions to total stress are considered, to knowing: the stresses being produced by each one of the indenters; the biaxial tension to balance the free area of pressure. Finally, by using all contributions to total stress and determining the principal stresses, the magnitude of maximum-shear-stress at each point of elastic body it could be obtained. In order to confront the model with the reality, by associating to each point its maximum-shear-stress respective, patterns of lines representing isostresses were obtained; such patterns were compared with a photo-elasticity image, showing a good agreement. .
Study of reverberation pattern and its cancellation method in shallow water
Authors: Yang Shiuh-Kuang , Chiu Shih-Ming , Wei Ruey-Chang
Published: March 2008

In shallow water, the primary limitation of the performance of active sonar is the reverberation that originates from volume and boundaries scattering as well as multi-path propagation. There?fore, reverberation cancelation is an important research topic for increasing the performance of active sonar in shallow water. In this research, the reverberation pattern is simulated using MAT?LAB software. The simulated frequency is 30-kHz in the research. There are two main aims of this work. The first is to create the signals that include the reverberation and the target. The second is to perform the reverberation cancelation for the active sonar in shallow water. The analysis of the reverberation for the spherical target is based on the propagation theory of image source, surface scattering of Rayleigh criterion of roughness, bottom scattering of Lambert?s Law, and multiple scattering. The signal containing the reverberation and the target is then compressed or enhanced by AGC (Automatic Gain Control). The echo of the target is then distinguished through the method of cross correlation. The follow?ing phenomena can be found: (a) AGC can compress the signal in a speci?c dynamic range. (b) cross correlation can be used to locate and distinguish the echoes of the target in a high reverberation environment.
Dual-series equations formulation for static deformation of plates with a partial internal line support
Authors: Sompornjaroensuk Yos , Kiattikomol Kraiwood
Published: March 2008

The paper deals with the application of dual-series equations to the problem of rectangular plates having at least two parallel simply supported edges and a partial internal line support located at the centre where the length of internal line support can be varied symmetrically, loaded with a uniformly distributed load. By choosing the proper finite Hankel transform, the dual-series equations can be reduced to the form of a Fredholm integral equation which can be solved conveniently by using standard techniques. The solutions of integral equation and the deformations for each case of the plates are given and discussed in details.
Phase diagrams modified by interfacial penalties
Authors: Atanackovic T.M. , Huo Y. , Jelicic Z. , Müller I.
Published: March 2008

The conventional forms of phase diagrams are constructed without consideration of interfacial energies and they represent an impor?tant tool for chemical engineers and metallurgists. If interfacial energies are taken into consideration, it is intuitively obvious that the regions of phase equilibria must become smaller, because there is a penalty on the formation of interfaces. We investigate this phe?nomenon qualitatively for a one-dimensional model, in which the phases occur as layers rather than droplets or bubbles. The modified phase diagrams are shown in Chapters 3 and 4.
The solution of certain loss of contact between a plate and unilateral supports
Authors: Sompornjaroensuk Yos , Kraiwood Kiattikomol
Published: March 2008

This paper examines the loss of contact between a square plate and the unilateral supports under uniformly distributed load. Since the plate is rested on the unilateral supports, it will have the regions of lost contact between a plate and the supports due to the absence of restraining corner force at the plate corners. This leads to the mixed boundary conditions and these conditions are then written in the form of dual-series equations which can further be reduced to a Fredholm integral equation by taking advantage of finite Hankel transform technique. Numerical results are given for the deflections of free edge and deflections along the middle line of the plate with deferent values of the Poisson?s ratio. In addition, the deflection surface is also presented. From the investigation, it can be indicated that the loss of contact is decreased upon the increasing Poisson?s ratio.
Mass transfer effects on vertical oscillating plate with heat flux
Authors: Muthucumaraswamy R. , Manivannan K.
Published: March 2008

Theoretical solution of unsteady viscous incompressible flow past an infinite vertical oscillating plate with uniform heat flux and mass diffusion is presented here, taking into account of the homogeneous chemical reaction of first-order. The temperature from the plate to the fluid at an uniform rate and the mass is diffused uniformly. The dimensionless governing equations has been obtained by the Laplace transform method, when the plate is oscillating harmonically in its own plane. The effects of velocity and concentration are studied for different parameters like phase angle chemical reaction parameter, thermal Grashof number, mass Grashof number Schmidt number and time are studied. The so?lutions are valid only for small values of time t. It is observed that the velocity increases with decreasing phase angle ?t or chemical reaction parameter.
An approach to the optimization of thin-walled cantilever open section beams
Authors: Andjelic Nina , Milosevic-Mitic Vesna
Published: March 2008

An approach to the optimization of the thin-walled cantilever open section beams subjected to the bending and to the constrained torsion is considered. The problem is reduced to the determination of minimum mass, i.e. minimum cross-sectional area of structural thin-walled I-beam and channel-section beam elements for given loads, material and geometrical characteristics. The area of the cross-section is assumed to be the objective function. The stress constraints are introduced. Applying the Lagrange multiplier method the equations, whose solutions represent the optimal values of the ratios of the parts of the chosen cross-section, are formed. The obtained results are used for numerical calculation.
Stalking: Notion, characteristics and social responses
Authors: Nikolic-Ristanovic Vesna , Kovacevic-Lepojevic Marina
Published: March 2008

In the last two decades stalking phenomenon is recognized and actualized in the world in professional, scientific circles, in media and the everyday talk. Recently, stalking is identified as specific and complex problem studied separately from domestic violence, workplace abuse, sexual harassment, threats, following, homicide, voyeurism and the other phenomenon to which stalking may or not be related. This paper is aimed to determine the notion of stalking and its relationship with similar phenomena, to review the research about the prevalence and nature of stalking, as well as to review the measures for its prevention, supporting victims and prosecution of offenders. Finally, the paper intend to contribute toward initiation of research and legal reforms regarding stalking victimisation in Serbia.
Victims of stalking in India: A study of girl college students in Tirunelveli City
Authors: Jaishankar Karuppannan , Kosalai Puthisigamani
Published: March 2008

The word 'stalking' was not commonly known in India, until Priyadharshini Mattoo's case (1996) hit the headlines. Eve teasing, a colloquial word for gender harassment is popularly known and Tamil Nadu Prohibition of Eve-Teasing Act, 1998 on that was developed after the brutal killing of a girl named Sarika Shah in Chennai. Though, stalking is there in the past, it was not acknowledged with this terminology and it was always merged with Eve teasing. On the other hand, stalking is much graver than Eve teasing and it is an obsessive behaviour. After the Matoo's case, the Indian Criminal Justice System awoke and the National Commission for Women is ready with a draft Bill (Sexual Assault Prevention Bill) to make the Indian Penal Code more effective against the menace of stalkers. Research studies related to stalking in India are sparse and there is a need to study this phenomenon in depth. This paper presents some results from a study of stalking victims among Girl College students at Tirunelveli City, Tamil Nadu, India. In-depth questionnaire data are drawn on to investigate the course and nature of prolonged stalking in 150 self-defined victims. Findings indicate a pattern of repeated intrusions, the stalking harassment methods, lack of reporting behaviour, and effects of stalking on the victims.
Responsibility of Serbia for genocide: Application of the Convention on the prevention and punishment of the crime of genocide
Authors: Tejic Mirjana
Published: March 2008

On February 26th 2007, International Court of Justice claimed Serbia responsible for failing to prevent genocide and punish perpetrators underlining its' responsibility to cooperate with International Criminal Tribunal for former Yugoslavia. Although it was confirmed genocide has been committed in Srebrenica 1995, Serbia is not obliged to pay financial reparations. Judgment makes distinction between individual and three-fold state responsibility for genocide, based on Convention on the Prevention and Punishment of the Crime of Genocide and other sources of international law. There are evident disagreements among judges on jurisdiction, interpretation rules, even on meritum of the case. Many questions still remain open especially what precedent effects will have on establishment of state's dolus specialis and how it will influence the reconciliation process in the region.
Formal and informal systems in prison
Authors: Macanovic Nebojsa
Published: March 2008

Main question of modern penological theory and penitentiary practise is finding deeper social sense through general goal, which we define as resocialization of prisoners and creating conditions for successful life after leaving prison. Success of resocialization depends also on attitude of prisoners to formal system and following the rules and principles of that system. Opposite to formal system which is based on prison staff and normative system (Law of carrying out of a sentence and Book of regulations for house rules), exists informal system which is based on prisoners and their mutual relationships, as well as on prisoner's codex, and which has negative influence to resocilazation process. Attitude of prisoners to formal system during serving a sentence represents very significant indicator of prisoner's readiness for return to community and acceptance of society norms.
Common Variation in the FTO Gene Alters Diabetes-Related Metabolic Traits to the Extent Expected Given Its Effect on BMI
Authors: Freathy Rachel M. , Timpson Nicholas J. , Lawlor Debbie A. , Pouta Anneli , Ben-Shlomo Yoav , Ruokonen Aimo , Ebrahim Shah , Shields Beverley , Zeggini Eleftheria , Weedon Michael N. , Lindgren Cecilia M. , Lango Hana , Melzer David , Ferrucci Luigi , Paolisso Giuseppe , Neville Matthew J. , Karpe Fredrik , Palmer Colin N.A. , Morris Andrew D. , Elliott Paul , Jarvelin Marjo-Riitta , Davey Smith George , McCarthy Mark I. , Hattersley Andrew T. , Frayling Timothy M.
Published: March 2008

OBJECTIVE—Common variation in the FTO gene is associated with BMI and type 2 diabetes. Increased BMI is associated with diabetes risk factors, including raised insulin, glucose, and triglycerides. We aimed to test whether FTO genotype is associated with variation in these metabolic traits.

RESEARCH DESIGN AND METHODS—We tested the association between FTO genotype and 10 metabolic traits using data from 17,037 white European individuals. We compared the observed effect of FTO genotype on each trait to that expected given the FTO-BMI and BMI-trait associations.

RESULTS—Each copy of the FTO rs9939609 A allele was associated with higher fasting insulin (0.039 SD [95% CI 0.013–0.064]; P = 0.003), glucose (0.024 [0.001–0.048]; P = 0.044), and triglycerides (0.028 [0.003–0.052]; P = 0.025) and lower HDL cholesterol (0.032 [0.008–0.057]; P = 0.009). There was no evidence of these associations when adjusting for BMI. Associations with fasting alanine aminotransferase, γ-glutamyl-transferase, LDL cholesterol, A1C, and systolic and diastolic blood pressure were in the expected direction but did not reach P < 0.05. For all metabolic traits, effect sizes were consistent with those expected for the per allele change in BMI. FTO genotype was associated with a higher odds of metabolic syndrome (odds ratio 1.17 [95% CI 1.10–1.25]; P = 3 × 10−6).

CONCLUSIONS— FTO genotype is associated with metabolic traits to an extent entirely consistent with its effect on BMI. Sample sizes of >12,000 individuals were needed to detect associations at P < 0.05. Our findings highlight the importance of using appropriately powered studies to assess the effects of a known diabetes or obesity variant on secondary traits correlated with these conditions.
First-principles studies of the electronic structure and optical properties of AgBO3 (B=Nb,Ta) in the paraelectric phase
Authors: Cabuk Suleyman , Simsek Sevket
Published: March 2008

The electronic energy-band structure, density of states (DOS), and optical properties of AgBO3 in the paraelectric cubic phase have been studied by using density functional theory within the local density approximation for exchange-correlation for the first time. The band structure shows a band gap of 1.533 eV (AgNbO3)and 1.537 eV (AgTaO3)at (M-⌈)point in the Brillouin zone. The optical spectra of AgBO3 in the photon energy range up to 30 eV are investigated under the scissor approximation. The real and imaginary parts of the dielectric function and — thus the optical constants such as reflectivity, absorption coefficient, electron energy-loss function, refractive index, and extinction coefficient — are calculated. We have also made some comparisons with related experimental and theoretical data that is available.
Double-Alekseev inverse scattering method in the stationary axi-symmetric vacuum gravitation field equations
Authors: Wang Chun-Yan , Gui Yuan-Xing , Gao Ya-Jun
Published: March 2008

We present a new improvement to the Alekseev inverse scattering method. This improved inverse scattering method is extended to a double form, followed by the generation of some new solutions of the double-complex Kinnersley equations. As the double-complex function method contains the Kramer-Neugebauer substitution and analytic continuation, a pair of real gravitation soliton solutions of the Einstein’s field equations can be obtained from a double N-soliton solution. In the case of the flat Minkowski space background solution, the general formulas of the new solutions are presented.
Ligament Laxity Following Inversion Injury with and without Chronic Ankle Instability
Authors: Hubbard Tricia J.
Published: March 2008

Background: Not all patients develop chronic ankle instability (CAI) after one or more lateral ankle sprains; some seem to heal or adjust to the ankle laxity after injury. Why do some patients develop CAI and others are able to cope and return to normal function? The purpose of this study was to examine ligament laxity between subjects with and without CAI. Materials and Methods: Sixteen subjects with unilateral CAI and 16 subjects without participated in the study. Ligament laxity was measured with an instrumented ankle arthrometer. The arthrometer measured ankle joint motion for anterior/posterior displacement (mm) during loading at 125 N and inversion/eversion rotation (degrees of ROM) during loading at 4000 N/mm. For each dependent variable a 2 × 2 mixed model ANOVA was run with the between factor being group (CAI, No CAI) and the within factor with repeated measures being side (involved, uninvolved). Results: A significant group by side interaction for anterior displacement (F1,30 = 370.085, p < 0.001), and inversion rotation (F1,30 = 7.455, p = 0.010) was found. There was significantly more anterior displacement and inversion rotation for the involved ankles of the CAI group than the involved ankles of the stable group and the uninvolved ankles of the CAI group. Conclusion: Based on the results of this study it appears that the increased anterior displacement and inversion rotation compared to patients without instability may be why subjects develop CAI. Although the patients without instability have a history of more than one lateral ankle sprain, they did not demonstrate increased laxity, which may be the reason why they do not complain of the functional impairment demonstrated in subjects with CAI.
Combined Ipsilateral Fractures of Talus and Calcaneus
Authors: Seybold Dominik , Schildhauer Thomas A. , Muhr Gert
Published: March 2008

Introduction: The purpose of this study was to evaluate the frequency of combined ipsilateral talar and calcaneal fractures, the fracture pattern in combination and the clinical outcome of the combined operative treatment. Materials and Methods: Out of 950 patients with calcaneal fractures and 190 patients with talar fractures treated operatively between 1984 and 2003, 11 patients (1% of calcaneal and 6% of talar fractures) were identified with combined ipsilateral talar and calcaneal fractures. Closed reduction and external fixation was performed in one patient with a crush foot injury, and ORIF in all other patients and fractures. All patients underwent clinical and radiological evaluation after a minimum followup period of one year using the AOFAS-Hindfoot Score. Results: Seven patients had central talar body and 4 patients talar neck fractures. Nine calcaneal fractures were extraarticular sustentaculum, as well as processus anterior fractures, and two were intraarticular fractures. Average followup was 6 (range, 1 to 12.5; median, 4.5) years. There were no perioperative complications related to ORIF. AOFAS-Hindfoot-Score averaged 78.6 (range, 50 to 100). The followup x-rays showed post-traumatic arthritis in the ankle joint in 3 patients and in the subtalar joint in five. AVN with peudarthorsis was present in one patient with an intraarticular calcaneal fracture. Patients with intraarticular calcaneal fractures presented with the worst functional results (AOFAS-Score, 50 and 64), none of these patients required a secondary ankle or subtalar fusion. All other patients had good and excellent functional outcome. Conclusion: Combined ipsilateral talar and calcaneal fractures are rare injuries. Extraarticular calcaneal fractures are more common in this injury pattern, while there was no preference for either talar neck or talar body fractures. Operative treatment with anatomic open reduction and internal fixation may result in favorable clinical outcome. Combined surgical approaches to the hindfoot did not result in increased morbidity.
Testing the intermediate disturbance hypothesis in species‐poor systems: A simulation experiment for mangrove forests
Authors: Piou Cyril , Berger Uta , Hildenbrandt Hanno , Feller Ilka C.
Published: March 2008

Questions:

What factors influence tree species diversity of mangrove forests, an example of species‐poor systems? What are the respective importance and interactions of these factors? Is the intermediate disturbance hypothesis applicable to such systems?

Methods:

We used the spatially explicit individual‐based model Ki Wi to investigate the effects on species diversity of perturbation frequency and intensity, different abiotic conditions, and interspecific competition simulated at the individual level. The simulation system considered the three dominant Caribbean mangrove species: Rhizophora mangle, Avicennia germin‐ans and Laguncularia racemosa, applying species‐specific growth and mortality characteristics. Firstly, effects on species dominance of the abiotic conditions nutrient availability and porewater salinity were tested with two competition scenarios. Secondly, the effect of perturbation frequency and intensity were investigated with selected abiotic conditions.

Results:

Abiotic conditions influenced species dominance and, in extreme cases, excluded one or two species. Abiotic and competition settings controlled the successional dynamics and the response of species dominance to perturbation regimes. A response consistent with the intermediate disturbance hypothesis was observed only with a configuration of plant interaction in which one species behaved as a pioneer so that succession occurred by competitive exclusion.

Conclusions:

We suggest that successional dynamics interact with the intensity and timing of perturbations and determine whether or not mangrove tree diversity conforms to predictions of the intermediate disturbance hypothesis. For mangroves, these successional dynamics are site‐specific depending on abiotic conditions and species configurations.
Gibbs Paradox and the Concepts of Information, Symmetry, Similarity and Their Relationship
Authors: Lin Shu-Kun
Published: March 2008

We are publishing volume 10 of Entropy. When I was a chemistry student I was facinated by thermodynamic problems, particularly the Gibbs paradox. It has now been more than 10 years since I actively published on this topic [1-4]. During this decade, the globalized Information Society has been developing very quickly based on the Internet and the term information is widely used, but what is information? What is its relationship with entropy and other concepts like symmetry, distinguishability and stability? What is the situation of entropy research in general? As the Editor-in-Chief of Entropy, I feel it is time to offer some comments, present my own opinions in this matter and point out a major flaw in related studies. [...]
Reactive Spinning of Cyanate Ester Fibers Reinforced with Aligned Amino‐Functionalized Single Wall Carbon Nanotubes
Authors: Che Jianfei , Chan‐Park Mary B.
Published: March 2008

We report a new approach of reactive spinning to fabricate thermosetting cyanate ester micro‐scale diameter fibers with aligned single walled carbon nanotubes (SWNTs). The composite fibers were produced by first dispersing the SWNTs (1 wt %) in cyanate ester (CE) via solvent blending, followed by pre‐polymerization, spinning and then multiple‐stage curing. The pre‐polymerization, spinning and post‐spinning cure temperatures were carefully controlled to achieve good spun crosslinked fibers. Both pristine and amino‐functionalized SWNTs were used for the reinforced fiber spinning. Amino‐functionalized SWNTs (f‐SWNTs) were prepared by reacting acid‐treated SWNTs with toluene 2,4‐diisocyanate and then ethylenediamine (EDA). FTIR, optical microscopy and scanning electron microscopy (SEM) showed that the amino‐functionalized SWNTs were covalently and uniformly dispersed into the cyanate ester matrix and aligned along the fiber axis. The alignment was further confirmed using polarized Raman spectroscopy. The composite fibers with aligned amino‐functionalized SWNTs possess improved tensile properties with respect to neat CE fibers, showing 85, 140, and 420% increase in tensile strength, elongation and stress‐strain curve area (i.e., toughness), respectively. NH2‐functionalization of SWNTs improves their dispersibility, alignment and interfacial strength and hence tensile properties of composite spun fibers. Fiber spinning to align SWNTs using thermosetting resin is novel. Others have reported fiber spinning to align SWNTs in thermoplastics. However, thermosetting CE resins offer the advantages of low and controllable viscosity during spinning and reactivity with amino functional groups to enable f‐SWNT/CE covalent bonding.
Synthesis of Thin, Oriented Zeolite A Membranes on a Macroporous Support
Authors: Kuzniatsova Tatsiana A. , Mottern Matthew L. , Chiu William V. , Kim Yanghee , Dutta Prabir K. , Verweij Henk
Published: March 2008

Continuous, thin, oriented zeolite A membranes are produced by a two‐step synthesis on macroporous α‐Al2O3 supports. In the first step, zeolite A nano‐cubes with ∼350‐nm edges are prepared as a native impurity phase in zeolite Y synthesis dispersions, the support surface is pre‐modified with a cationic polymer having a selective affinity for zeolite A. The thus‐treated support is contacted with a colloidally stable dispersion of zeolite A and Y mixture in water, which results in selective, dense‐packed deposition of the zeolite A cubes with one face aligned to the average support surface. In a second step of hydrothermal epitaxial growth, the seed layer grows epitaxially into a continuous, meso‐defect free, ∼1 µm thick zeolite A layer, already after 1 h of treatment. This microstructure of the membrane compares very favorably to what is commonly obtained. The pH value of the zeolite mixture suspension is found to have a major influence on seed layer morphology, and thereby, on the quality and orientation of zeolite A membrane after short synthesis times. The final zeolite A membrane thickness and morphology is controlled by varying secondary growth synthesis time. The approach presented is thought to be of generic use for the preparation of oriented zeolite membranes.
Crystallinity‐Controlled Germanium Nanowire Arrays: Potential Field Emitters
Authors: Li Liang , Fang Xiaosheng , Chew Han Guan , Zheng Fei , Liew Tze Haw , Xu Xijin , Zhang Yunxia , Pan Shusheng , Li Guanghai , Zhang Lide
Published: March 2008

We report a simple method, oblique angle deposition, to directly synthesize aligned Ge nanowire arrays on a Si substrate. This process is accomplished by tilting the Si substrate and adjusting the incident angle of the evaporated Ge vapor flux with respect to the substrate normal to 87°. The resultant crystallinity of the Ge nanostructures can be tuned to either amorphous or poly‐ and single‐crystalline, depending on the substrate temperature and evaporation rate. The effects of thermal treatment on the morphology and structure of the Ge nanowires are discussed in detail. The field‐emission measurements show that increasing the annealing temperatures to about 550 °C results in a gradual increase in the maximum current density and a decrease in the turn‐on voltage, because of the decreased wire density originating from melting of the Ge nanowires. The field‐enhancement factor analysis shows there is an optimum range for Ge wire density and aspect ratio to obtain good emission performance. Ge nanowire arrays might find potential application in the field emitters of the future.
Biologically Inspired Surfaces: Broadening the Scope of Roughness**
Authors: Nosonovsky Michael , Bhushan Bharat
Published: March 2008

Superhydrophobicity can be used for many applications that require non‐adhesive and water‐repellent surfaces. A successful design of superhydrophobic surfaces requires a correct assessment of the surface roughness effect on wetting. Roughness is an important property in surface mechanics, physics, chemistry, and biology, and it is critical for many tribological applications. Roughness can be defined in different ways, and the definition should be adequate to the problem under investigation. Our recent studies of biological and biomimetic superhydrophobic surfaces show that traditional roughness parameters, such as the root‐mean‐square, correlation length, or fractal dimension, are not always appropriate for the analysis of wetting. This is, in particular, due to the hierarchical nature of wetting mechanisms and interfaces. We discuss the effect of roughness on wetting mechanisms and relevant roughness parameters and ways to broaden the concept and scope of surface roughness.
Enantioselective Transfer Hydrogenation of Aliphatic Ketones Catalyzed by Ruthenium Complexes Linked to the Secondary Face of β‐Cyclodextrin
Authors: Schlatter Alain , Woggon Wolf‐D.
Published: March 2008

Ruthenium‐η‐arene complexes attached to the secondary face of β‐cyclodextrin catalyze the enantioselective reduction (ee up to 98%) of aliphatic and aromatic ketones in aqueous medium in the presence of sodium formate (HCOONa).
Ectocranial suture closure in Pan troglodytes and Gorilla gorilla: Pattern and phylogeny
Authors: Cray James , Meindl Richard S. , Sherwood Chet C. , Lovejoy C. Owen
Published: March 2008

The order in which ectocranial sutures undergo fusion displays species‐specific variation among primates. However, the precise relationship between suture closure and phylogenetic affinities is poorly understood. In this study, we used Guttman Scaling to determine if the modal progression of suture closure differs among Homo sapiens, Pan troglodytes, and Gorilla gorilla. Because DNA sequence homologies strongly suggest that P. troglodytes and Homo sapiens share a more recent common ancestor than either does with G. gorilla, we hypothesized that this phylogenetic relationship would be reflected in the suture closure patterns of these three taxa. Results indicated that while all three species do share a similar lateral‐anterior closure pattern, G. gorilla exhibits a unique vault pattern, which, unlike humans and P. troglodytes, follows a strong posterior‐to‐anterior gradient. P. troglodytes is therefore more like Homo sapiens in suture synostosis. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.
Insights from the inside: Histological analysis of abnormal enamel microstructure associated with hypoplastic enamel defects in human teeth
Authors: Witzel C. , Kierdorf U. , Schultz M. , Kierdorf H.
Published: March 2008

We studied the abnormalities in enamel microstructure associated with enamel hypoplasia in human teeth from the early medieval (5th–7th century AD) cemetery of Barbing, Germany, using light and scanning electron microscopy. The main aim of the study was to test the hypothesis that by analyzing the microstructure of fully formed enamel it is possible to reconstruct the reaction pattern of secretory ameloblasts to stress events leading to enamel hypoplasia. From the histological findings, a sequence of increasing impairment of secretory ameloblast function involving three thresholds was deduced. Surpassing of each of these thresholds is assumed to result in characteristic changes in enamel microstructure attributable to specific functional/morphological alterations of secretory ameloblasts. Based on our results we propose a model identifying the principal factors influencing the reaction of secretory ameloblasts to stress. The present study demonstrates that by including microscopic analysis in the study of enamel hypoplasia, it is possible to obtain a more complete picture of the formation of these developmental defects than is possible by inspection of crown surface features alone, and to draw more substantiated conclusions about the possible nature of developmental defects of enamel. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.
The bipedalism of the Dmanisi hominins: Pigeon‐toed early Homo?
Authors: Wallace Ian J. , Demes Brigitte , Jungers William L. , Alvero Martin , Su Anne
Published: March 2008

In the recent description of the hominin postcranial material from Dmanisi, Georgia, Lordkipanidze and colleagues (Lordkipanidze et al. [2007] Nature 449: 305–310) claim that the Dmanisi hominins walked with more medially oriented feet than do modern humans. They draw this functional inference from two postcranial features: a wide talar neck angle and a slight medial torsion of the tibia. However, we believe that the data provided by the authors fail to support their conclusions. Talar neck angle and tibial torsion values from the Dmanisi specimens fall comfortably within the range of modern human variation. We further submit that foot orientation cannot be reliably deduced from the tibia and talus alone. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.
Kombinatorische Übergangsmetallkatalyse: Mischungen einzähniger Liganden zur Kontrolle der Enantio‐, Diastereo‐ und Regioselektivität
Authors: Reetz Manfred T.
Published: March 2008

Der vorliegende Aufsatz befasst sich mit einem neuartigen Konzept der kombinatorischen homogenen Übergangsmetallkatalyse, das über die herkömmliche parallelisierte Synthese modularer Liganden hinausgeht. Dieses Konzept beruht auf dem Einsatz von Mischungen einzähniger Liganden La und Lb, die in Gegenwart von Übergangsmetallen (M) neben den beiden Homo‐Kombinationen [MLaLa] und [MLbLb] ebenfalls die Hetero‐Kombination [MLaLb] bilden. Ist die letztgenannte Hetero‐Kombination reaktiver und selektiver als die jeweiligen Homo‐Kombinationen, erhält man ein verbessertes Katalysatorsystem, ohne dass dabei neue Liganden synthetisiert werden müssen. Hierbei ist eine Kontrolle der Enantio‐, Diastereo‐ und Regioselektivität möglich.
Effect of the axial vibration of screw on total shear strain distribution of melt in single‐screw extruders
Authors: Feng Yan‐Hong , Qu Jin‐Ping , He He‐Zhi , Liu Bin , Cao Xian‐Wu , Wen Sheng‐Ping
Published: March 2008

Single screw extruders are known as good melt pumps with the high, stable pressure needed for part extrusion. However they have a particular disadvantage in achieving good mixing. In a vibration‐induced polymer extruder (VIPE), a vibration force field (VFF) is introduced into the whole extrusion process by the axial vibration of screw, which affects the mixing process. It is well‐known that the total shear strain (TSS) has been widely used to measure the effect of melt mixing in a laminar system. In this study, an analytic model for pulsating TSS was developed and the TSS distribution of the melt in the screw channel of the melt conveying section in a VIPE was calculated to further understand the time‐dependent dynamic laminar mixing process. A comparison of the TSS distribution of melt in screw channel with and without vibration shows that the TSS of melt increases with the application of vibration and the larger the vibration frequency and amplitude are, the larger the TSS that the melt may experience while melt traveling through the melt conveying section, which is favorable for melt mixing. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008