bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction of PIN and PGP transport mechanisms in auxin distribution-dependent development
Authors: Mravec Jozef , Kubeš Martin , Bielach Agnieszka , Gaykova Vassilena , Petrášek Jan , Skůpa Petr , Chand Suresh , Benková Eva , Zažímalová Eva , Friml Jiří
Published: September 2008

The signalling molecule auxin controls plant morphogenesis via its activity gradients, which are produced by intercellular auxin transport. Cellular auxin efflux is the rate-limiting step in this process and depends on PIN and phosphoglycoprotein (PGP) auxin transporters. Mutual roles for these proteins in auxin transport are unclear, as is the significance of their interactions for plant development. Here, we have analysed the importance of the functional interaction between PIN- and PGP-dependent auxin transport in development. We show by analysis of inducible overexpression lines that PINs and PGPs define distinct auxin transport mechanisms: both mediate auxin efflux but they play diverse developmental roles. Components of both systems are expressed during embryogenesis, organogenesis and tropisms, and they interact genetically in both synergistic and antagonistic fashions. A concerted action of PIN- and PGP-dependent efflux systems is required for asymmetric auxin distribution during these processes. We propose a model in which PGP-mediated efflux controls auxin levels in auxin channel-forming cells and, thus, auxin availability for PIN-dependent vectorial auxin movement.
Temporal progression of hypothalamic patterning by a dual action of BMP
Authors: Ohyama Kyoji , Das Raman , Placzek Marysia
Published: September 2008

In the developing chick hypothalamus, Shh and BMPs are expressed in a spatially overlapping, but temporally consecutive, manner. Here, we demonstrate how the temporal integration of Shh and BMP signalling leads to the late acquisition of Pax7 expression in hypothalamic progenitor cells. Our studies reveal a requirement for a dual action of BMPs: first, the inhibition of GliA function through Gli3 upregulation; and second, activation of a Smad5-dependent BMP pathway. Previous studies have shown a requirement for spatial antagonism of Shh and BMPs in early CNS patterning; here, we propose that neural pattern elaboration can be achieved through a versatile temporal antagonism between Shh and BMPs.
p21 differentially regulates DNA replication and DNA-repair-associated processes after UV irradiation
Authors: Soria Gaston , Speroni Juliana , Podhajcer Osvaldo L. , Prives Carol , Gottifredi Vanesa
Published: September 2008

Although p21 upregulation is required to block cell-cycle progression following many types of genotoxic insult, UV irradiation triggers p21 proteolysis. The significance of the increased p21 turnover is unclear and might be associated with DNA repair. While the role of p21 in nucleotide excision repair (NER) remains controversial, recent reports have explored its effect on translesion DNA synthesis (TLS), a process that avoids replication blockage during S phase. Herein, we analyze the effect of p21 on different PCNA-driven processes including DNA replication, NER and TLS. Whereas only the CDK-binding domain of p21 is required for cell-cycle arrest in unstressed cells, neither the CDK-binding nor the PCNA-binding domain of p21 is able to block early and late steps of NER. Intriguingly, through its PCNA-binding domain, p21 inhibits the interaction of the TLS polymerase, pol η (pol eta), with PCNA and impairs the assembly of pol η foci after UV. Moreover, this obstruction correlates with accumulation of phosphorylated H2AX and increased apoptosis. By showing that p21 is a negative regulator of PCNA-pol η interaction, our data unveil a link between efficient TLS and UV-induced degradation of p21.
Coping Strategies for Low Frequency Noise
Authors: Leventhall Geoff , Benton Stephen , Robertson Donald
Published: September 2008

A small group (n=9), whose complaints of low frequency noise had not been resolved by Environmental Health Officers and related care professionals, were invited to attend a series of intervention sessions led by a psychotherapist. The aims of the sessions were to improve the participants' coping strategies and their quality of life, in order to relieve them from some of the distress caused by their belief that they were exposed to low frequency noise. Prior to the psychotherapy sessions the group was evaluated on a number of self report questionnaires, which measured individual responses for reaction to low frequency noise, quality of life, quality of coping and a personality questionnaire (Insights™ Discovery Preference Evaluator). A before and after, within group analysis of responses was based upon repeat measures of the three behavioural response questionnaires for noise reactivity, quality of life and coping. A general reduction in the subjects' stress levels was shown, suggesting positive effects of psychotherapy upon symptoms that had, in this group's case, proved resistant to improvement by conventional local authority and specialist interventions. This ‘therapeutic’ approach to LFN interventions could lead to improved health and effectiveness and fewer demands on local services. Although the techniques of tinnitus management were informative, analogy between the problems of low frequency noise sufferers and those of tinnitus sufferers fails at the point where low frequency noise sufferers believe that an external agency is the cause of their problems.
Structural Morphology Issues in Conceptual Design of Double Curved Systems
Authors: Bagneris M. , Motro R. , Maurin B. , Pauli N.
Published: September 2008

Non-standard architecture is generally defined by complex double curved systems. We described in this paper three morphogenesis processes. Analytic forms are mainly characterized by regular geometries like cylinders or spheres and portions of these geometric forms are present throughout the history of architecture. Mechanical forms appeared mainly during the second half of the twentieth century, under the impetus of pioneers like Frei Otto: These shapes are guided by an equilibrium condition, the expression of which is known as “form-finding”. Funicular, prestressed and self stressed systems are clearly in this second class. Initiated by the so-called “Bilbao effect” a new trend of double curved systems appeared, characterized by complete free forms that we name flexible forms. The objective is to analyse these classes of forms in relation with parameters of forces, material, technology and structural composition, which are coupled in the conceptual design process. We introduce mainly the coupling between form and structural composition (structural morphology). The last class reveals a lack of links between the parameters, and a complete dislocation of the successive steps of the design process. The evolution from analytical forms to flexible forms, via mechanically-constrained forms is examined in order to determine which constraints designers faced either due to their own choice or for other causes.
Deployment Simulations of Inflatable Tensegrity Structures
Authors: Russell Colin , Tibert Gunnar
Published: September 2008

Tensegrity structures are attractive as deployable space structures since they are composed mainly of flexible tension members and can thus easily be folded. To automatically deploy such structures it is proposed that the tension members are replaced or enclosed by thin-film tubes, which form a continuous volume. The structure deploys when this volume is pressurised. This concept was studied by numerical simulations of the deployment process in a zero-gravity environment using the control volume method for the fluid-structure interaction. First, single z-folded and coiled tubes were analysed to determine suitable element size, number of control volumes and gas flow rate. Then one- and three-stage tensegrity masts were modelled, folded and finally deployed. The study showed that the deployment concept is feasible.
Point of Connection Voltage Regulation Strategies for AC Connected Large Offshore Wind Farms
Authors: Chondrogiannis Stamatios , Barnes Mike , Osborne Mark , Yao Liangzhong
Published: September 2008

The offshore wind energy generation industry is developing rapidly in the UK. The long submarine cable connection needed between the wind turbine generators and the onshore Point of Connection (PoC) introduces additional difficulties for compliance with the GB Grid Code reactive power requirement. To address this problem, this paper investigates different PoC voltage regulation strategies. The methods are compared in terms of control requirements, fault behaviour of the wind farm and economics. It is shown that for long connection distances to the PoC, additional dynamic reactive compensation equipment and/or a tap-changing transformer at the offshore platform will probably be needed for Grid Code Compliance. It is shown that a strategy where a STATCOM solely regulates the PoC voltage, leads to increased capital expenditure. However, this provides advantages in respect to its simplicity, speed of PoC voltage regulation and wind turbine behaviour for a fault at the PoC.
Experimental Investigations on the Effect of Overlap Ratio and Blade Edge Conditions on the Performance of Conventional Savonius Rotor
Authors: Kamoji M. A. , Kedare S. B. , Prabhu S. V.
Published: September 2008

The torque of a conventional Savonius rotor is studied experimentally for overlap ratio from 0.10 to 0.70, blade edge condition (flat and round) and the change in Reynolds number. The results indicate that the coefficient of static torque improves marginally for round edged rotors for rotor angles up to 45°. The coefficient of static torque decreases as the overlap ratio is increased to 0.70 from 0.50 and is independent of the Reynolds numbers studied in the range between 120000 to 200000. Wind tunnel blockage ratio is studied. The power coefficient increases with the increase in the Reynolds number, whereas the coefficient of static torque is independent of the Reynolds number in the range studied. The coefficient of power, torque coefficient and coefficient static torque are independent of blockage ratios at a given Reynolds number.
Dynamic Behavior of Stand-Alone Wind Turbine Generator System with Wind Turbine Performance Deterioration
Authors: Wakui Tetsuya , Yokoyama Ryohei , Arase Hiroyuki
Published: September 2008

It is necessary to establish an autonomous condition monitoring for small-scale stand-alone wind turbine generator systems, which are mainly utilized in regions with no electricity. As a first phase of its development, dynamic behavior of a system with the performance deterioration of a wind turbine is investigated using a dynamic simulation model. In the target system, a straight-wing vertical axis wind turbine is mainly operated at a constant tip speed ratio, i.e., a maximum power coefficient point, without an anemometer from the viewpoints of the simplicity of system configuration and the low system cost. Numerical analyses show that the performance deterioration of the wind turbine causes a significant decrease in the power generating capability during operation due to a deviation in the operating point of the system from a maximum power coefficient point. Furthermore, a system characteristic that is closely linked to the performance deterioration of the wind turbine and can be estimated during operation without an anemometer is identified.
Modelling Analysis in Power System Small Signal Stability with Grid-Connected Wind Farms of DFIG Type
Authors: Wang Chen , Shi Libao , Wang Liming , Ni Yixin
Published: September 2008

In this paper, the modelling and small signal stability analysis of grid-connected wind farms of doubly-fed induction generator (DFIG) type are conducted. A simplified and practical DFIG model is presented firstly. The stator flux-oriented vector control based method is utilized to implement stator active and reactive powers control in modelling rotor-side converter control strategy. The power system small signal stability analysis is then carried out to explore and exploit the essential impacts on the existing power grid due to the high penetration of grid-connected wind farms of DFIG type. Finally, numerical results illustrate the effectiveness and validity of the proposed model and method.
Sound Pressure Levels in Food Courts of Shopping Centres
Authors: Pimentel Roberto Leal , Esmeraldo Lara Barrocas Soares , Navarro Manuelina Porto Nunes
Published: September 2008

Two potentially critical food courts were selected from a group of twelve of such eating establishments, and sound pressure levels (SPLs) were measured and analysed with regard to acoustic quality. Initial measurements of background noise with the food courts almost empty revealed high SPLs in such places. Measurements taken with varied number of users showed an increase in SPLs in accordance to the cocktail party effect, ending up in values of 75 dBA and 81 dBA for each food court. Design aspects of the courts were discussed in order to improve the acoustical quality.
Variation of Energy Conversion Efficiencies of Stationary Photovoltaic Systems with Latitudes
Authors: Sharan Anand M.
Published: September 2008

In this paper, the energy conversions of stationary photovoltaic systems are calculated at different latitudes for 182 days of a year to cover various angular orientation of sun's rays on the earth. On a given day, the incident energy flux of the sun is resolved into three components, and the conversion efficiency is based on the flux normal to the panels. The normalizing value considered is that obtained by the solar tracking process. The results show that, on an average, one can improve the output of the stationary panels by about 66.67% by resorting to tracking. The research points out the loss of energy when the sun is behind the panels at low vertical angles.
Greening Electricity Production: A Success Story of Multi-Level Governance Convergence and Innovation
Authors: Dinica Valentina
Published: September 2008

This paper analyzes the diffusion of wind power in Spain from the perspective of the multi-level governance features that contributed to the outcomes observed so far. Public authorities at all governance levels designed strategies that converged to reinforce each other's positive effects on potential investors and social acceptance. Next to implementing traditional policy instruments for financial support, Spanish authorities also engaged in direct capital investments in wind power, in the form of public-private partnerships, to reduce the risk perceptions of investors. Besides, regional authorities developed long-term strategies for wind power deployment to accommodate investors' plans. The convergence of these three strategies has led to a high investment interest and resulted in an exponential annual increase in the installed capacity of wind power.
A Finite Element Solution of Structure-Borne Sound Attenuation for a Lightweight Timber Floor
Authors: Bard D. , Sonnerup J. , Sandberg G.
Published: September 2008

Structure-borne sound attenuation of lightweight timber floor structures has been investigated by high-resolution numerical calculation methods. Two models have been studied both experimentally and numerically. The first considers a continuous chipboard plate and a supporting beam. The second considers two plates that are fastened on one beam. Damping effects, which arise from the two different discontinuities, are included. The real-valued modulus of elasticity is replaced with a complex value. In the calculations, the orthotropic material characteristics of the building material have also been taken into account. The results from the calculations and laboratory measurement confirm that the attenuation rate is highly dependent on the excitation location, if all the other parameters remain the same.
Acoustical Demands for the Conductor's Location
Authors: Meyer Jürgen
Published: September 2008

For a conductor standing in front of an orchestra, some requirements place special demands on the room-acoustical conditions at his location: the control of a homogeneous sound of the individual string groups, the dynamic balance between different instrument sections, the orchestral dynamics as a whole and the balance between soloists or singers and the orchestra, and the spaciousness of the full sound to be expected in the audience area. Furthermore the conductor has to choose the seating arrangement of the orchestra. Whereas the listeners' loudness impression mainly is determined by the diffuse field level in the hall, the conductor's loudness impression depends predominantly on the direct sound and maybe additionally by early reflections coming from the walls around the orchestra and from above. Spatial impression is perceived generally in the frontal hemisphere; this leads to difficulties for the conductor in assessing the spatial impression in the audience area: As in the horizontal plane, he hears predominantly the direct sound of the orchestra, he can perceive a spatial impression only from the space above his location or from higher room sections behind the orchestra. Because of the directivity of the musical instruments, different seating arrangements of the instrument sections affect the tonal impression of the listeners; but as in all arrangements the players sit facing the conductor, he does not hear the influence of the directivity at his location and can assess it only by listening from the audience area.
Relevance of Absolute and Relative Energy Content in Seismic Evaluation of Structures
Authors: Kalkan Erol , Kunnath Sashi K.
Published: September 2008

A reassessment of input energy measures taking into consideration the characteristics of near fault ground motions is presented. The difference between absolute and relative energy input to structural systems is shown to be more significant for near-fault than far-fault records. In particular, the coherent velocity pulse contained in near-fault records resulting from a distinctive acceleration pulse rather than a succession of high frequency acceleration spikes produces sudden energy demand in the early phase of the response and is typically larger than the total energy accumulated at the end. Studies using idealized pulses indicate that input energy is a function of the shape and period of the velocity pulse. For spectral periods shorter than pulse period, greater absolute energy is input into the system rather than relative energy, while the reverse is true for spectral periods larger than the pulse period. The discrepancy between two energy definitions is initiated by the phase difference in ground velocity and system relative velocity, and it tends to be minimal as the pulse period approaches to system vibration period. The significance of these findings, based on linear SDOF simulations, is further investigated by examining the nonlinear seismic response of a group of realistic buildings subjected to near-fault recordings with and without apparent acceleration pulses. This study concludes that selection of appropriate energy measure for near-fault accelerograms should be based on the shape and period of dominant pulse in the record, and the vibration properties of the structural system.
Behaviour of Unbonded Post-Tensioned One-Way Concrete Slabs
Authors: Ellobody Ehab , Bailey Colin G.
Published: September 2008

The behaviour of unbonded post-tensioned one-way concrete slabs is investigated experimentally and numerically in this paper. Two tests were conducted by the authors to measure the strains in the tendon during the post-tensioning stage and during the ultimate load test. The slabs were one-way simply-supported and reinforced with 15.7 mm nominal diameter seven-wire mono-strand tendons. Prestress losses were measured and a comparison with current design codes showed that the calculated design losses were higher than those measured. The load-deflection behaviour and modes of failure are presented for the two tests. A nonlinear finite element model, incorporating the correct load transfer from the tendon to the concrete, was developed and verified against the tests. The model also ensured that the profile of the tendon retained its correct shape during deformation. A parametric study was conducted to study the effects on the global structural behaviour due to the change in the slab's geometry, prestress load, concrete strength and boundary conditions. The experimental and numerical results were compared with values calculated using current design codes. It is shown that the ultimate loads calculated using current codes are conservative for the unbonded post-tensioned one-way concrete slabs investigated in this study. The results presented in this paper provide a valuable insight into the behaviour of unbonded post-tensioned concrete slabs during the construction phase and under ultimate load.
Strength of Gapped K-connections with HSS and Longitudinal Double Plates
Authors: Jeong Sang-Min , Choi Young-Hwan , Bae Kyu-Woong , Lee Moon-Sung , Moon Tae-Sup , Lee Li-Hyung
Published: September 2008

The research reported herein investigated the behavior of gapped K-connections comprising square hollow structural sections (HSS) for a chord and a compression branch, a high-strength tensile rod for a tension branch, and a pair of longitudinal plates separated by distance for a connecting element. The main experimental parameters for 12 specimens were the width-to-thickness ratio of the chord (2γ) with 16.7 ≤ 2γ ≤ 33.3, the width ratio between the compression branch and the chord (ß1) with 0.5 ≤ ß1 ≤ 0.875, and the width ratio between the tension branch to the chord (ß2) with 0.42 ≤ ß2 ≤ 0.82. Experimental results showed that the general failure mode was a combination of chord plastification and punching shear. It was also found that the width ratio between the tension branch and the chord (ß2) has a greater effect on the connection strength. Since there was no equation in CIDECT that could be used to estimate the strength of the connections tested in this study, a new equation was proposed from the yield line analysis.
Structural Capacities of Tension Side for CFT Square Column-To-Beam Connections with Combined-Cross Diaphragm
Authors: Choi Sungmo , Lee Seonghui , Hong Sungduk , Kim Jinho
Published: September 2008

The purpose of this study is to suggest a new CFT column-to-beam connection type, which will have an axis direction that takes into consideration the asymmetry of connections. Through experimental study and finite element analysis, the study also compares the structural capacities of the new CFT column-to-beam connection type with those of existing connection types. Existing connection types for comparative study are those with an interior diaphragm and through diaphragm. The new connection type suggested uses a combined-cross diaphragm, featuring a column flange penetration in the major-axis direction and an interior diaphragm in the minor-axis direction. In order to analyze and compare the initial stiffness and strengths of the connections considered simple tension tests along with finite element analysis were performed on the specimens, while idealizing the tension-applied beam flange. Stress concentrations, according to the geometric configurations and load transfer mechanisms of diaphragms, were analyzed through finite element analysis. The results show that the existing connection types, in terms of initial stiffness and ultimate strength, do not precede the combined-cross diaphragm, and that the stress concentration on the connection can be relieved by improvement to the detail.
Artificial Networks for Spatial Analysis
Authors: Benoudjit Mohamed Amine , Coates Paul S.
Published: September 2008

This paper tests digital representation techniques which can be used by artificial neural networks in a computer-aided design (CAD) environment to analyze and classify architectural spaces. We developed two techniques for encoding volumetric data: vertex representation and feature space representation, as input for artificial neural networks. We tested how two different kinds of artificial neural networks, perceptron networks and self-organizing maps, could recognize given shapes in these representational formats. We have found that a one-layer perceptron can be used to classify shapes even when presented with input vectors composed of real numbers. These spatial representation techniques provide a method for using ANNs for architectural purposes.
Fitness, Performance and Injury Prevention Strategies for the Senior Golfer
Authors: Versteegh Theodore H. , Vandervoort Anthony A. , Lindsay David M. , Lynn Scott K.
Published: September 2008

Current demographic trends in countries where golf is popular indicate that the number of senior golfers will increase significantly in the coming decades. Thus golf coaches and teaching professionals benefit from having a working knowledge about the aging process and how this will affect the older golfer's performance and participation level. Playing golf can promote health benefits such as from the walking exercise, but it can also lead to injury concerns; e.g., musculoskeletal problems from repetitive strain of excessive practice. Therefore, the purpose of this article is to review literature pertinent to the key performance and health issues that should be considered when dealing with the older golfer. Some strategies for targeted management of the senior golfer's typical health concerns such as osteoarthritis are provided, along with a call for further research on how best to disseminate such information widely to the large and growing population of seniors who enjoy this activity
An Introduction to Using Mental Skills to Enhance Performance in Golf: Beyond the Bounds of Positive and Negative Thinking
Authors: Finn Jon
Published: September 2008

It is commonly believed that psychology plays an important role in golf. The aims of this article are: I) to highlight and consolidate the intuitive link between psychology and golf; and ii) to provide an overview of mental skills which players, coaches and club professionals can use on a day-to-day basis to enhance performance in golf. Specifically this article will focus on the mental skills of imagery self-talk, relaxation and goal setting; and demonstrate how these mental skills can impact on concentration, anxiety, confidence and motivation
Do Expert Golfers Keep Their Heads Still While Putting?
Authors: Lee Timothy D. , Ishikura Tadao , Kegel Stefan , Gonzalez Dave , Passmore Steven
Published: September 2008

The putting patterns of five expert and 11 less-skilled golfers were examined to understand the nature of head movement that occurred during the putting stroke. As expected, the less-skilled golfers moved their heads in the direction of the backswing, then reversed and moved it in the direction of the downstroke during the putt. In contrast, and contrary to expectations, the experts did the reverse – they moved their head in a direction that was opposite to the direction of the putter. The strokes of both the experts and less-skilled golfers revealed closely matched timing constraints, indicating a strong preference to organize these actions as a single coordination pattern
Aerodynamic Effects of Road Topography and Meteorological Conditions on Time-Trialling Cycling Performance
Authors: Marqués-Bruna Pascual , Grimshaw Paul
Published: September 2008

This paper examines the interactive aerodynamic effects of road topography and meteorological conditions on time-trialling cycling performance. Aerodynamics and cycling performance were modelled using a fictitious cyclist completing a 40-km time-trial with simulated power outputs of 164 W (recreational level), 255 W (well-trained) and 394 W (elite) Virtual topographical conditions encompassed altitudes of up to 2500 m and ±2% road gradients. Meteorological variations incorporated 970–1040 mb barometric pressures, 0–40°C air temperatures, 0–100% relative humidity levels and ±2 m/s wind velocities. Interactions between physical altitude and weather were expressed in terms of the associated air density Drag force was calculated, and aerodynamic power, cycling speed and finishing time were estimated using mathematical modelling. Prediction equations were developed using curve fitting. Non-standard atmospheric conditions alter the pressure altitude and density altitude of a particular race location. With increasing air density, drag force rises rapidly in direct proportion, but aerodynamic power increases and cycling performance declines in a non-linear fashion. Windy conditions and hilly terrain add to race time exponentially with air density. An Excel spreadsheet was developed which may be used by time-triallists to predict cycling performance and adjust pacing according to road topography and forecast weather.
Assessment Influence on Peak Power Output and Road Cycling Performance Prediction
Authors: Smith Mark F.
Published: September 2008

The influence of cycling assessment on peak power output and road-based cycling performance prediction was evaluated in twelve well-trained amateur cyclists (mean ± SD; age, 35 ± 8 yr; body mass, 74.1 ± 6.7 kg; stature: 181 ± 6 cm). Determining peak power output, cyclists completed a graded i) ramp assessment on a Kingcycle air-braked ergometer (PPOKING), ii) continuous assessment on a SRM electromagnetically-braked ergometer (PPOSRM), and iii) discontinuous assessment on a Monark friction-braked ergometer (PPOMON). Furthermore, a 40-km road-based individual cycle race was completed. Throughout each, power was measured using an SRM Training System. Despite no differences (p > 0.05) in V̇DO2peak across graded assessments, PPOKING (387 ± 49W) was 3.6% higher (p < 0.05) than PPOSRM (373 ± 38W) and 9% higher (p < 0.05) than PPOMON (352 ± 41W). Relating assessment-derived peak power output with road-based performance (mean power: 288 ± 36W; mean time 62:00 ± 3:13 min:sec), PPOKING (r = 0.94: p < 0.001), PPOSRM (r = 0.87; p< 0.001) and PPOMON (r = 0.90; p < 0.001) were strongly correlated to mean power, but not time (PPOKING; r = −0.41; p > 0.05: PPOSRM; r = −0.42; p > 0.05: PPOMON; r = −0.41: p > 0.05). Independent of determination, peak power output was strongly related to performance power and may provide effective means of obtained training and racing intensities.
Research and Application of a Novel Adaptive 3-D Medical Image Interpolation Method Using ROI
Authors: Jian-Lin Ma , Jian Wu , Qun Wang , Feng Ye , Sheng-Yang Luo
Published: September 2008

Interpolation of medical slice images is an important procedure in 3D reconstruction. To overcome the shortcomings, which are brought by current algorithms, such as blur of objects' boundary, high cost-time etc, this paper proposes a novel adaptive image interpolation algorithm that is suitable to medical image processing. This algorithm makes good use of characteristics of anatomical structures and voxel relativity and uses the following strategies: firstly to judge whether the interpolated point belongs to ROI (Region Of Interest), then to get the best point-pair according to comparability principle of surface. The experimental results show that the novel method enables new images to better accord with the practical demand not only in gray but anatomical structures as well. Moreover, this algorithm is much better than the current algorithms of this kind in time costing. Therefore, our algorithm is more suitable to volume rendering which is one method of 3D reconstruction.
The Latest MPEG Standards and Industrial Requirements for Media Streaming
Authors: Ali Maaruf
Published: September 2008

This paper presents an overview of image compression covering JPEG, the MPEG Standards, H.262, H.263 and H.264, VQ, Wavelet and Fractal Transforms. Error resilience in terms of an unequal error protection (UEP) scheme is also covered. The report concludes with a very brief mention of the protocols used in streaming multimedia data.
Multi-Paradigm Modeling of Fracture of a Silicon Single Crystal under Mode II Shear Loading
Authors: Buehler Markus J. , Cohen Alan , Sen Dipanjan
Published: September 2008

We report a novel multi-paradigm multi-scale approach based on a combination of the first principles ReaxFF force field with an empirical Tersoff potential. Our hybrid multi-scale simulation model is computationally efficient and capable of treating thousands of atoms with QM accuracy, extending our ability to simulate the dynamical behavior of a wider range of chemically complex materials such as silicon, silica and metal-organic compounds. It is implemented in the Python based Computational Materials Design Facility (CMDF). We exemplify our method in a study focused on a systematic comparison of the fracture dynamics in silicon under mode II shear versus mode I tensile loading. We find that the mode II crack tends to branch at an angle of approximately 45 degrees once the crack speed approaches 38% of the Rayleigh-wave speed. In contrast, the mode I crack continuously propagates in the direction of the initial crack, and only makes a slight change of direction towards 10 degrees once fracture instabilities occur. Our results reveal fundamental differences of fracture dynamics under mode I versus mode II loading.
Towards Dynamic Integration, Scheduling and Rescheduling of Scientific Applications
Authors: Yu Lei , Magoulès Frédéric
Published: September 2008

The evolution of grid computing generates new requirements for distributed application development and deployment. There is no standard way of registering these applications, describing their input parameters and output results and monitoring their progress in the Grid environment. The Web Services Architecture (WSA) is an ideal technology to integrate legacy applications into the Grid. Adopting this service-oriented architecture, a model is implemented to achieve the dynamic deployment, scheduling and rescheduling of scientific applications. The model treats all components (Resource Service and Service Scheduler) as WSRF-compliant services which support the applications integration with underlying native platform facilities and facilitate the construction of the hierarchical scheduling system.
Pareto Optima of Multicriteria Integer Linear Programs
Authors: De Loera Jesús A. , Hemmecke Raymond , Köppe Matthias
Published: September 2008

We settle the computational complexity of fundamental questions related to multicriteria integer linear programs, when the dimensions of the strategy space and of the outcome space are considered fixed constants. In particular we construct: (1) polynomial-time algorithms to determine exactly the number of Pareto optima and Pareto strategies; (2) a polynomial-space polynomial-delay prescribed-order enumeration algorithm for arbitrary projections of the Pareto set; (3) a polynomial-time algorithm to minimize the distance of a Pareto optimum from a prescribed comparison point with respect to arbitrary polyhedral norms; and (4) a fully polynomial-time approximation scheme for the problem of minimizing the distance of a Pareto optimum from a prescribed comparison point with respect to the Euclidean norm.
Solving Lot-Sizing Problems on Parallel Identical Machines Using Symmetry-Breaking Constraints
Authors: Jans Raf
Published: September 2008

Production planning on multiple parallel machines is an interesting problem, both from a theoretical and practical point of view. The parallel machine lot-sizing problem consists of finding the optimal timing and level of production and the best allocation of products to machines. In this paper, we look at how to incorporate parallel machines in a mixed-integer programming model when using commercial optimization software. More specifically, we look at the issue of symmetry. When multiple identical machines are available, many alternative optimal solutions can be created by renumbering the machines. These alternative solutions lead to difficulties in the branch-and-bound algorithm. We propose new constraints to break this symmetry. We tested our approach on the parallel machine lot-sizing problem with setup costs and times, using a network reformulation for this problem. Computational tests indicate that several of the proposed symmetry-breaking constraints substantially improve the solution time, except when used for solving the very easy problems. The results highlight the importance of creative modeling in solving mixed-integer programming problems—specifically, the potential added value of symmetry-breaking constraints.
A Set-Covering Approach with Column Generation for Parsimony Haplotyping
Authors: Lancia Giuseppe , Serafini Paolo
Published: September 2008

We introduce an exact algorithm, based on integer linear programming (ILP), for the parsimony haplotyping problem (PHP). The PHP uses molecular data and is aimed at the determination of a smallest set of haplotypes that explain a given set of genotypes. Our approach is based on a set-covering formulation of the problem, solved by branch and bound with both column and row generation. Existing ILP methods for the PHP suffer from the large size of the solution space, when the genotypes are long and with many heterozygous sites. Our approach, on the other hand, is based on an effective implicit representation of the solution space, and allows the solution of both real data and simulated instances, which are very hard to solve for other ILPs.
Financial Reporting and Conflicting Managerial Incentives: The Case of Management Buyouts
Authors: Fischer Paul E. , Louis Henock
Published: September 2008

We analyze the effect of external financing concerns on managers' financial reporting behavior prior to management buyouts (MBOs). Prior studies hypothesize that managers intending to undertake an MBO have an incentive to manage earnings downward to reduce the purchase price. We hypothesize that managers also face a conflicting reporting incentive associated with their efforts to obtain external financing for the MBO and to lower their financing cost. Consistent with our hypothesis, we find that managers who rely the most on external funds to finance their MBOs tend to report less negative abnormal accrual prior to the MBOs. In addition, the relation between external financing and abnormal accruals is tempered when there are more fixed assets that can serve as collateral for debt financing.
Simulating Sensitivities of Conditional Value at Risk
Authors: Hong L. Jeff , Liu Guangwu
Published: September 2008

Conditional value at risk (CVaR) is both a coherent risk measure and a natural risk statistic. It is often used to measure the risk associated with large losses. In this paper, we study how to estimate the sensitivities of CVaR using Monte Carlo simulation. We first prove that the CVaR sensitivity can be written as a conditional expectation for general loss distributions. We then propose an estimator of the CVaR sensitivity and analyze its asymptotic properties. The numerical results show that the estimator works well. Furthermore, we demonstrate how to use the estimator to solve optimization problems with CVaR objective and/or constraints, and compare it to a popular linear programming-based algorithm.
Learning, Forgetting, and Sales
Authors: Villas-Boas Sofia Berto , Villas-Boas J. Miguel
Published: September 2008

Sellers of almost any product or service rarely keep their prices constant through time and frequently offer price discounts or sales. This paper investigates an explanation of sales as a way for uninformed consumers to be willing to experience the product, and learn about its fit, and where informed consumers may forget about (or change) their preferences. We investigate the role of the rate of consumer forgetting on the timing between sales, and of the rate of consumer learning and menu costs on the length of a sale. The rate of consumer forgetting can be linked to the length of purchase cycle and the level of consumer involvement. We show that the discount frequency and the discount depth are increasing in the rate of consumer forgetting, and that the discount frequency is increasing in the learning rate. The duration of a sale is increasing in the rate of consumer forgetting and the rate of consumer learning.
Data Set—Choice-Based Revenue Management: Data from a Major Hotel Chain
Authors: Bodea Tudor , Ferguson Mark , Garrow Laurie
Published: September 2008

In this paper, we describe data collected from five U.S. properties of a major hotel chain that can be used to benchmark the performance of choice-based revenue management (RM) algorithms. The process used to collect this data illustrates subtle complexities involved in extracting product availability information from current RM systems and sheds new light on practical issues that need to be addressed to successfully implement choice-based RM systems. The data described in this paper is publicly available at the journal's website at http://msom.pubs.informs.org .
Impact of Epitope Specificity and Precursor Maturation in Pro-B–Type Natriuretic Peptide Measurement
Authors: Goetze Jens Peter , Dahlström Ulf , Rehfeld Jens F , Alehagen Urban
Published: September 2008

Background: Cardiac-derived natriuretic peptides are sensitive plasma markers of cardiac dysfunction. Recent reports have disclosed a more complex molecular heterogeneity of B-type natriuretic peptide precursor (proBNP)-derived peptides than previously suggested. In this study, we examined the impact of epitope specificity and precursor maturation on plasma measurement of proBNP-derived peptides.

Methods: We compared 2 assays, N-terminal proBNP and proBNP 1–76, in a randomly collected set of human plasma specimens (n = 370). Additionally, we evaluated the clinical performance of 4 assays with different epitope specificities in a cohort of elderly patients presenting with symptoms associated with heart failure (n = 415).

Results: Comparison of N-terminal proBNP with proBNP 1–76 measurement in plasma revealed a high correlation on regression analysis (r2 = 0.91, P < 0.0001). Nevertheless, the proBNP 1–76 assay measured lower concentrations in the high range than the N-terminal proBNP assay. Correlations between assay measurements in a clinical setting were comparable for all the assays (r2 approximately 0.57–0.83), and ROC analyses revealed area-under-the-curve values ranging between 0.77 and 0.81 for identifying reduced left ventricular ejection fraction. In parallel, all assays displayed comparable abilities in predicting long-term mortality.

Conclusions: Our results reveal marked assay differences in analytical assay comparison, contrasting the overall comparable clinical performance in cardiovascular diagnostics or prognosis in the elderly.
Engagement and Effectiveness of Parent Management Training (Incredible Years) for Solo High-Risk Mothers: A Multiple Baseline Evaluation
Authors: Lees Dianne G. , Ronan Kevin R.
Published: September 2008

The effectiveness ofThe Incredible Yearsparent-training program with a small sample of four high risk solo mothers in a public clinic setting was assessed. All families had a number of risk factors for early drop-out and poor outcomes. Mindful of resource limitations in the public setting, economical strategies were used to enhance attendance rates and engagement. For the outcome evaluation, a multiple baseline across participants design was used. Participants attended a 2-hour group treatment session weekly for twenty weeks, with booster sessions at 2 months and 4 months following treatment. Participants had sons aged between 6 years and 9 years diagnosed with ADHD. Family functioning was assessed from a pretreatment interview schedule, measures of child behaviour and parent and family functioning. Participants also completed program satisfaction and program evaluation measures. Results showed: (a) all mothers engaged with and finished the program, (b) improvement in family functioning, (c) improvements in some teacher and parent reports of child behaviour, (d) increased parenting confidence, (e) reduced stress and depression levels for most parent participants, and (f) reports of better parent–child relationships. Additionally, participants all reported being highly satisfied with the program. Findings overall support the use of easy to do engagement strategies and the use of theIncredibleYears parent-training program as an effective, low cost and early step intervention for families at higher risk in a day-to-day practice setting. The use of this intervention in an overall stepped care approach is considered and discussed.
Can a Theory of Mind Disruption Help Explain OCD Related Metacognitive Disturbances?
Authors: O'Kearney Richard , Nicholson Cherie
Published: September 2008

This study investigated whether individual differences in obsessive-compulsive symptoms and in thought–action fusion are related to theory of mind abilities. One hundred and ninety-two adult participants completed self-reports of obsessive–compulsive symptoms (OCI-R), thought–action fusion (TAF), private self-consciousness (PSC) and self-reflectiveness (SR) as mentalising abilities, and anxiety and depression. A nonintrospective method examining participants' implicit structure of their lexicon for ‘knowing’ was used to assess theory of mind. Private self-conciousness and SR added to the prediction of OCD symptoms independently of TAF and depression but did not mediate the relationship between TAF and OCD symptoms. Participants high in thought–action fusion gave a greater emphasis to the certainty dimension of the mental lexicon and placed lesser importance on the source of information dimension than those low in TAF. Our results provide preliminary evidence of a relationship between theory of mind and thought–action fusion. People disposed to thought–action fusion are more likely to make a significance judgment about ‘knowing’ based on the degree of certainty than on reference to the source of knowledge. Identifying disruptions to theory of mind abilities in OCD provides links to solid theory and evidence about metacognitive development and may help integrate cognitive processing and cognitive appraisal models of OCD.
Delay to Seek Treatment for Anxiety and Mood Disorders in an Australian Clinical Sample
Authors: Thompson Anna , Issakidis Cathy , Hunt Caroline
Published: September 2008

Effective treatments for common anxiety and mood disorders exist, yet epidemiological studies reveal that the unmet need for treatment in the community remains high. This study investigates the significance of the initial delay to first seek professional help in this unmet need for treatment in an Australian sample. Help-seeking history was retrospectively reported by 273 new referrals to a specialist anxiety treatment clinic who had a primary diagnosis of an anxiety (78%) or mood disorder (22%). Clinical, demographic and attitudinal variables were tested as potential predictors of length of the delay. Average help-seeking delay was 8.2 years (range 0–72 years). Younger age at symptom onset and slower problem recognition were associated with delayed help-seeking, and older people were more likely to report longer delays. We conclude that delays to first seek treatment are long and contribute significantly to the unmet need for treatment for anxiety and mood disorders, and that lack of problem recognition is a significant barrier to help-seeking.
Exploring the Effectiveness of the FRIENDS Program in Reducing Anxiety Symptoms Among South African Children
Authors: Mostert Jemona , Loxton Helene
Published: September 2008

The prevalence of anxiety symptoms among South African children is reported to be significantly higher than in other parts of the world. The need for an effective anxiety prevention and early intervention program for use with South African children is urgently needed. The aim of the present study was therefore to determine whether the Australian FRIENDS program could effectively reduce the anxiety symptoms, as measured by the Spence Children's Anxiety scale (SCAS), among a sample of South African children from low socioeconomic background. The program evaluation employed a quasi-experimental, nonequivalent control group design that followed participants (N= 46) over a course of 10 months. Within group effects and between group effects revealed that the FRIENDS program had little statistically significant postintervention effect on the anxiety symptoms of this sample, but had significant effects in the longer term, at 4 months and 6 months follow-up. The implications of these results for the South African context are discussed.