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The concept of apparent weakening by adding true negative stiffness to a structure has been previously introduced by the authors in order to reduce simultaneous drifts, accelerations, and displacements in a structure without yielding or permanent deformation in the main system. A novel negative stiffness device (NSD) that generates true negative stiffness has been developed, built, and tested and has been previously described by the authors in terms of operation and analytical and numerical modeling. This paper presents results that represent proof-of-concept for weakening with the use of the NSD based on the shake table testing of a 3-story seismically isolated structure, equipped with these devices complemented by viscous dampers. The NSD is shown to have a significant effect on the superstructure response by reducing floor accelerations, story drift, and the base shear and upon the addition of dampers, also results in a reduction in isolator displacements. Moreover, this paper provides validati...

Seismic analysis, design, and performance assessment of buildings, bridges, and safety-related nuclear structures is based on two or three translational components of earthquake ground motion. Although rotational components (rocking and torsional) may contribute significantly to translational and torsional response and damage, they are not considered in design and assessment because their intensity and frequency content are not measured by accelerograms deployed in the free field. A method for developing rotational time series by first deconstructing the three translational time series of a ground motion recorded at one station into body waves is presented in this paper. The body waves are then reassembled to generate rotational time series. Point and line source representations of the fault rupture are considered. Results of the single station procedure are presented using rotational acceleration spectra and compared with the multiple-station-based geodetic method. The spectra are similar at periods greater than 1s. The spectral ordinates computed using the geodetic method are significantly smaller at shorter periods, which is attributed to the underlying assumption of a plane surface for the recorded data at any time instant in the method.

The main objective of this study is to perform a parametrical study associated with the effects of the earthquake ground motions on the seismic response of isolated curved bridges including soil–structure interaction. For the isolated bridge system, double concave friction pendulum bearings are placed between the deck and the piers, the abutments as isolation devices. A curved bridge is selected to exhibit the application for seismic isolation. The bridge is to be modeled and analyzed in a seismic zone with an acceleration coefficient of 0.7 g . The configuration of the bridge is a three-span, cast-in-place concrete box girder superstructure supported on reinforced concrete columns found on drilled shafts and on integral abutments founded on steel pipe piles. The bridge is located on site underlain by a deep deposit of cohesionless material. The drilled shaft–soil system is modeled by equivalent soil springs method, and is included in the finite element model. The soil is modeled as a series of springs connected to the drilled shaft at even intervals. The reduction of the internal forces on the deck for the isolated curved bridge is observed, if the forces are compared with those obtained for the non-isolated curved bridge.

Simplified methods of analysis described in codes and specifications for seismically isolated structures are always used either directly in special cases or for checking the results of nonlinear response history analysis (RHA). In this study, the maximum isolator displacements and base shears determined by nonlinear RHA are compared with those determined by the equivalent lateral force (ELF) procedure in order to assess the accuracy of the simplified method in the case of earthquakes with near field characteristics. Features of this study are that the ground motions used in analysis are selected and scaled using contemporary concepts and that the ground excitation is considered bi-directional. It is shown that the simplified method provides acceptably accurate predictions of shear isolator displacements and shear forces for a range of isolator properties and ground motions representative of stiff and soft soil conditions.

Lead–rubber bearings are seismic isolators that have been extensively used to protect buildings, bridges and mission-critical infrastructure from the damaging effects of earthquake shaking. Testing of isolators, including lead–rubber bearings, is conducted either for research purposes (for example, shake table testing) or for determination of their properties before their use in applications (prototype and quality-control testing). Testing is of significance as it (a) provides the data needed to validate complex models for analysis, and (b) results in basic mechanical properties of the tested isolators for use in analysis and design. Often testing has to be performed on reduced-size bearings and/or at conditions of reduced speed of motion due, primarily, to unavailability of testing equipment capable of testing full-size specimens at realistic dynamic conditions. When testing at reduced size, the conditions of testing need to be adjusted on the basis of scientific analysis so that the test results represent the behavior of the full-size prototype bearing. This paper examines the issue of testing of lead–rubber bearings at reduced scale and presents the necessary conditions for testing in order to correctly reproduce the critical effects of lead core heating on the characteristic strength of the bearing. Experimental results on large-size and reduced-size bearings are used to demonstrate the concepts. Copyright © 2010 John Wiley & Sons, Ltd.

Lead–rubber bearings are seismic isolators that have been used extensively to protect buildings, bridges and mission-critical infrastructure from the damaging effects of earthquake shaking. Under large-displacement cyclic motion, the strength of a lead–rubber bearing reduces due to energy dissipation and the resultant heating of the lead core. This paper proposes a method to incorporate strength degradation due to lead core heating in modeling the hysteretic behavior of lead–rubber bearings. The validity of the proposed model is investigated through comparing numerical and experimental results. The model is used to examine the effects of lead core heating on the dynamic response of an isolated structure. Copyright © 2010 John Wiley & Sons, Ltd.

Zonal flows in rotating systems have been previously shown to be suppressed by the imposition of a background magnetic field aligned with the direction of rotation. Understanding the physics behind the suppression may be important in systems found in astrophysical fluid dynamics, such as stellar interiors. However, the mechanism of suppression has not yet been explained. In the idealized setting of a magnetized beta plane, we provide a theoretical explanation that shows how magnetic fluctuations directly counteract the growth of weak zonal flows. Two distinct calculations yield consistent conclusions. The first, which is simpler and more physically transparent, extends the Kelvin-Orr shearing wave to include magnetic fields and shows that weak, long-wavelength shear flow organizes magnetic fluctuations to absorb energy from the mean flow. The second calculation, based on the quasilinear, statistical CE2 framework, is valid for arbitrary wavelength zonal flow and predicts a self-consistent growth rate of the zonal flow. We find that a background magnetic field suppresses zonal flow if the bare Alfven frequency is comparable to or larger than the bare Rossby frequency. However, suppression can occur for even smaller magnetic fields if the resistivity is sufficiently small enough to allow sizable magnetic fluctuations. Our calculations reproduce the $\eta/B_0^2 = \text{const.}$ scaling that describes the boundary of zonation, as found in previous work, and we explicitly link this scaling to the amplitude of magnetic fluctuations., Comment: 17 pages, 7 figures

Lead-rubber bearings are seismic isolators that have been used extensively to protect buildings, bridges, and mission-critical infrastructure from the damaging effects of earthquake shaking. In bridges, lead-rubber bearings are subjected to continuous movement due to service (traffic) and temperature effects. This paper presents data on the effects of cumulative travel on the mechanical properties of lead-rubber bearings based on an experimental investigation of both medium- and small-sized bearings. A theoretical interpretation of the test results is presented.

The energy dissipated per cycle and the characteristic strength of lead-rubber bearings reduce with increasing number of cycles as a result of heating of the lead core. The reduction is substantial depending on the geometric characteristics of the bearing and the speed of motion. This paper presents a theory that is capable of predicting the dependency on time of the characteristic strength and energy dissipated of lead-rubber bearings. The theory is based on predicting the temperature of the lead core and relating the temperature to the strength. A much simpler theory is also presented based on neglect of heat conduction through the steel shim and end plates of the bearing. The theory is useful in predicting the cyclic behavior of lead-rubber bearings for simplified analysis, in extrapolating experimental data from one scale to another and in developing models for dynamic response history analysis of seismically isolated structures that account for the time-dependent mechanical properties of the bearings. A companion paper presents results of eight tests of six lead-rubber bearings that provide verification of the theoretical solution.

The energy dissipated per cycle and the characteristic strength of lead-rubber bearings reduce with increasing number of cycles as a result of heating of the lead core. A theory which is capable of predicting the histories of temperature rise in the core, of the energy dissipated and of the characteristic strength of lead-rubber bearings has been presented in a companion paper. This paper presents a comparison of predictions of this theory to experimental results obtained in the testing of six lead-rubber bearings. The analytical predictions are found to be sufficiently accurate. Moreover, finite-element analyses results are presented that provide insight into the distribution of temperature in the lead core and end and shim plates of the bearings. These distributions confirm the assumptions made in the development of the theoretical solution.

The XY-friction pendulum (XY-FP) bearing is a modified Friction Pendulum (Earthquake Protection Systems, Inc., Vallejo, Calif.) bearing that consists of two perpendicular steel rails with opposing concave surfaces and a connector. The connector resists tensile forces, provides for independent sliding in the two principal directions of the isolators, and ideally, permits unhindered rotation about its vertical axis. Experimental studies on an XY-FP seismically isolated truss-bridge model were undertaken to study response under tridirectional excitations and to evaluate the use of XY-FP bearings for bridges. A truss bridge model was tested on a pair of earthquake simulators using acceleration orbits and near-field earthquake histories. The experimental results demonstrated the effectiveness of the XY-FP bearings as an uplift-prevention isolation system: the XY-FP bearings simultaneously resisted significant tensile loads and functioned as seismic isolators. The bidirectional horizontal response of the small-scale XY-FP isolation system was coupled due to the internal construction of the small-scale connectors that joined the two rails of each XY-FP bearing and the limited free-to-rotate capacity of the XY-FP bearings due to misalignment of the isolators during installation.

The collapse of wood buildings was one of the main contributors to the heavy death toll and economic losses during the 1995 Hyogo-ken Nanbu (Kobe) earthquake in Japan. In California, half of the property loss from the 1994 Northridge earthquake was attributed to wood construction. Based on damage observed in recent earthquakes, the seismic vulnerability of existing wood buildings under maximum credible seismic events is uncertain. The main objective of this study is to quantify the seismic collapse fragilities and collapse mechanisms of a two-story townhouse and three-story woodframe apartment building through numerical analyses. Three construction quality variants (poor, typical and superior) were considered for each building in order to assess the effects of construction qualities on seismic collapse fragilities. The buildings were also re-designed according to the 2006 edition of the International Building Code to quantify the seismic fragilities of modern woodframe construction. The results obtained suggest that the construction quality, excitation direction and wall finish materials can influence significantly the collapse fragilities of woodframe buildings. Copyright © 2008 John Wiley & Sons, Ltd.

There are currently no applicable hysteresis rules or nonlinear elements available in structural analysis software that can be used to exactly model triple Friction Pendulum bearings for response-history analysis. Series models composed of existing nonlinear elements are proposed since they can be immediately implemented in currently available analysis software. However, the behavior of the triple Friction Pendulum bearing is not exactly that of a series arrangement of single concave Friction Pendulum bearings—though it is similar. This paper describes how to modify the input parameters of the series model in order to precisely retrace the true force-displacement behavior exhibited by this device. Recommendations are made for modeling in SAP2000 and are illustrated through analysis of a simple seismically isolated structure. The results are confirmed by (a) verifying the force-displacement behavior through comparison with experimental data and (b) verifying the analysis through comparison to the results obtained by direct numerical integration of the equations of motion.

In spite of numerous recent outcome studies of extremely low birth weight (ELBW) infants, no data exist on their development prior to term. In this study we traced and compared the neurobehavioral development of 251 ELBW (< 1,000 g) and 240 low birth weight (LBW; 1,000 g–2,500 g) preterms born between 1995 and 2004 from 32 to 37 weeks postconceptional age (PCA), using the Neurobehavioral Assessment of the Preterm Infant (NAPI; Korner & Thom, 1990). Compared to the original NAPI cohort of 521 infants (born 1983–1989), the ELBW and LBW infants were at higher medical risk, displayed weaker motor development, a tighter scarf sign and popliteal angle at all or most PCAs, and a weaker cry at older PCAs; they did not differ in irritability and percent asleep ratings. Few differences were noted between the ELBW and LBW groups. Research is now needed to determine whether the 1995 to 2004 NAPI values of ELBW and LBW infants at 32 to 37 weeks PCA are predictive of later outcome of high-risk preterms.

This paper presents a summary of current practice and recent developments in the application of passive energy dissipation systems for seismic protection of structures. The emphasis is on the application of passive energy dissipation systems within the framing of building structures. Major topics that are presented include basic principles of energy dissipation systems, descriptions of the mechanical behavior and mathematical modeling of selected passive energy dissipation devices, advantages and disadvantages of these devices, development of guidelines and design philosophy for analysis and design of structures employing energy dissipation devices, and design considerations that are unique to structures with energy dissipation devices. A selection of recent applications of passive energy dissipation systems is also presented.

WOS: 000392316700018 This Collective Article presents information on 26 taxa belonging to 8 Phyla and extending from the western Mediterranean to the Levantine Sea. The new records were found in 9 countries as follows: Spain: first record for the Mediterranean of the crab Cancer bellianus; Algeria: further records of the alien fish Lagocephalus sceleratus in western Algerian waters; Italy: first report on the presence and establishment of the ctenophore Mnemiopsis leidyi in Lessina and Varano Lagoons (W. Adriatic) and of Penaeus aztecus in Corigliano Gulf (Italian Ionian). Moreover, the extension of the distribution range of the polychaete Branchiomma bairdi to W. Sicily as well as that of the crab Ocypode cursor and the bryozoan Catenicella paradoxa to E. Sicily are cited. Slovenia: the record of the rare saccoglossan gastropod Placida cremoniana from Piran (Gulf of Trieste) is the first for the Adriatic; Greece: the native sea slug Eubranchus farrani is the first from the Eastern Mediterranean; many sightings of the bamboo corals Isididae distributed along all the E. Ionian Sea and the establishment of P. aztecus in all Greek waters are also reported for first time; the westernmost extension of the alien urchin Diadema setosum in Cretan waters is cited and new sightings of the alien species Goniobranchus annulatus and Pterois miles are presented. Turkey: the alien fish Champsodon capensis is reported for first time from the Aegean Sea and the native acari Agauopsis microrhyncha from the Levantine Sea; a new observation of the alien crab Atergatis roseus in Gulluk Bay-Aegean is also mentioned; Cyprus: first records of the alien urchin D. setosum and Lobotes surinamensis in Cypriot waters; Lebanon: several sightings of Monachus monachus from Lebanese waters indicate a potential better status for the species in the area; Egypt: first records of the alien crab Dorippe quadridens and the alien gastropods Nerita sanguinolenta and Conomurex persicus from the Mediterranean Egyptian waters; extension of the distribution range of Diodora funiculata and Diodora rueppellii and a second record of the alien Fulvia fragilis in the same area. COST (European Cooperation in Science and Technology) Action TD1209 Alien Challenge; EEA [33-51/30.06.2015]; Suleyman Demirel UniversitySuleyman Demirel University [SDU-BAP3973-D2-14, 3973-D2-14]; IDRC-Canada through Alexandria research Centre for Adaptation to Climate Change (ARCA); COST (European Cooperation in Science and Technology) Action TD1209 Alien Challenge; EEA [33-51/30.06.2015]; Suleyman Demirel UniversitySuleyman Demirel University [SDU-BAP3973-D2-14, 3973-D2-14]; IDRC-Canada through Alexandria research Centre for Adaptation to Climate Change (ARCA) The author N. Babali would like to thank his colleague Ms Faiza Alliouche for information gathering. Gianna Servello & P. Balisteri acknowledge the COST (European Cooperation in Science and Technology) Action TD1209 Alien Challenge (GS) that partially funded the study of alien species recorded in the Italian Seas. P. Balisteri also wishes to thank Bruno Zava (Wilderness Studi Ambientali) for his advice. Fabio Crocetta acknowledges the East and South European Network for Invasive Alien Species - a tool to support the management of alien species in Bulgaria (ESENIAS-TOOLS) (EEA funded - Contract No. 33-51/30.06.2015) for supporting the study of alien species from central and eastern European countries; F. Amato (Schiavonea) and G. Rigido (Schiavone) kindly provided information, specimens and videos. Ch. Mytilineou would like to thank all the personnel who worked onboard during the surveys of the INTERREG II Greece-Italy & RESHIO projects, E. Kallias for the electronic storage of the photos and I. Maina & J. Dokos for map drawing. Kostas Kapiris and I. Maina are grateful to K. Tenekertzis, Ch. Dictiopoulos, S. Kavadas and the scientific coordinators of DCF Dr. Machias and Tserpes for providing relevant information and photographic material for P. aztecus. Vasilis Gerovasileiou & D. Poursanidis are grateful to Yiannis Iliopoulos and the Athos Scuba diving centre for providing the photographic material. S. Yapici & M. Celik would like to thank the local fisherman for providing samples and the anonymous reviewer for helpful and constructive comments. The study of F. Durucan & Y. O. Boyaci was financially supported by the Suleyman Demirel University, SDU-BAP3973-D2-14 project. Number: 3973-D2-14. P. Kleitou, F. Crocetta are grateful to D. Kletou (Cyprus), A. Antoniades (Cyprus) and S. Georgiou (Cyprus) who shared data and provided evidence. M. Bariche and F. Crocetta would like to acknowledge all colleagues, fishermen, scuba divers and friends who shared their photos and videos. The work of Moussa and A. Zenetos is part of a project entitled "Pattern of diversity and climate change in a Mediterranean transition zone", which was supported by IDRC-Canada through a small research grant provided by the Alexandria research Centre for Adaptation to Climate Change (ARCA) to the National Institute of Oceanography and Fisheries (NIOF), Egypt; thanks are also due to Mrs. Marwa Ismaeil and Mrs. Marwa Samir for their assistance. Finally, the authors would also like to thank N.J. Xentidis for drawing the map with the records as well as the anonymous reviewers for their useful and constructive comments.

Every maturity-dependent derivative contract entails a term structure. For example, when the value of the portfolio consisting of a long position in a stock and a short position in a vanilla option is expressed in units of its instantaneous exercise value, the resulting quantity defines a discount function. Thus, the derivative of the discount function with respect to the time left until maturity defines a term structure density function, and the "hazard rate" associated with the discount function determines the forward rates for the vanilla option portfolio. The dynamics associated with these quantities are obtained in the complete market setting. In particular, one can model vanilla options based on the associated forward rates. The formulation based on forward rates for options extends the approach based on modeling the implied volatility process. As an illustrative example, the initial term structure of the Black–Scholes model is considered. It is shown in this example that the implied volatility smile has the effect of making the option forward rates homogeneous across different strikes.

An experimental study investigating the influence of lateral displacement on the vertical stiffness of elastomeric and lead–rubber seismic isolation bearings is summarized. Two identically constructed low-damping rubber and lead–rubber seismic isolation bearings were subjected to a series of tests with varying levels of combined lateral displacement and axial (compressive) loading to study this relationship. The results of these tests showed the vertical stiffness decreases with increasing lateral displacement for each bearing tested. Additionally, the vertical stiffness data are used to evaluate four formulations for the estimation of the vertical stiffness as a function of the lateral displacement. From this comparison, two formulations, one based on the Koh–Kelly two-spring model and the other on a piecewise linear relationship, showed good agreement with the experimental data over the wide range of lateral displacements considered in this study.

The calibration of the risk-neutral density function for the future asset price, based on the maximisation of the entropy measure of Renyi, is proposed. Whilst the conventional approach based on the use of logarithmic entropy measure fails to produce the observed power-law distribution when calibrated against option prices, the approach outlined here is shown to produce the desired form of the distribution. Procedures for the maximisation of the Renyi entropy under constraints are outlined in detail, and a number of interesting properties of the resulting power-law distributions are also derived. The result is applied to efficiently evaluate prices of path-independent derivatives.

This paper describes an experimental program to examine the force-displacement behavior of a class of multi-spherical sliding bearings. The primary goal of the experiments is to test the validity of the theory developed in a companion paper that describes the behavior of these devices. Experimental work consisted of testing the three primary variations of these bearings in several configurations of different friction and displacement capacities. Most tests were carried out at slow speeds; however, some testing was also conducted at high speed (up to approximately 400Â mm/s) to examine the behavior under dynamic conditions. The results of experimental testing were generally found to be in very good agreement with the analytical results. It is shown that the forces and displacements at which transitions in stiffness occur are predictable and therefore controllable in design. Furthermore, the underlying principles of operation were confirmed by the fact that starting and stopping of sliding on the different surfaces occurred as expected from theory.

Groundwater recharge studies in semi-arid areas are fundamental because groundwater is often the only water resource of importance. This paper describes the water balance method of groundwater recharge estimation in three different hydro-climatic environments in eastern Mediterranean, in northwest Greece (Aliakmonas basin/Koromilia basin), in Cyprus (Kouris basin and Larnaka area) and in Jordan (northern part of Jordan). For the Aliakmonas basin, groundwater recharge was calculated for different sub-catchments. For the Upper Aliakmonas basin (Koromilia basin), a watershed-distributed model was developed and recharge maps were generated on a daily basis. The mean annual recharge varied between 50 and 75 mm/year (mean annual rainfall 800 mm/year). In Cyprus, the mean groundwater recharge estimates yielded 70 mm/year in the Kouris basin. In the Larnaka area, groundwater recharge ranged from 30 mm/year (lowland) to 200 mm/year (mountains). In Jordan, the results indicated recharge rates ranging from 80 mm/year for very permeable karstified surfaces in the upper part of the Salt basin, where rainfall reaches 500 mm/year to less than 10 mm/year and to only about 1 mm/year in the southernmost part of the basin. For the north part of Jordan, a watershed-distributed model was developed and recharge maps were generated. This water balance model was used for groundwater recharge estimations in many regions with different climatic conditions and has provided reliable results. It has turned out to be an important tool for the management of the limited natural water resources, which require a detailed understanding of regional hydro(geo)logical processes. Copyright © 2007 John Wiley & Sons, Ltd.

The principles of operation and force-displacement relationships of three novel spherical sliding isolation bearings are developed in this paper. These bearings are completely passive devices, yet exhibit adaptive stiffness and adaptive damping. That is, the stiffness and damping change to predictable values at calculable and controllable displacement amplitudes. The primary benefit of adaptive behavior is that a given isolation system can be separately optimized for multiple performance objectives and/or multiple levels of ground shaking. With the devices presented here, this is accomplished using technology that is inherently no more complex than what is currently used by the civil engineering profession. The internal construction consists of various concavesurfaces and behavior is dictated by the different combinations of surfaces upon which sliding can occur over the course of motion. As the surfaces upon which sliding occurs change, the stiffness and effective friction change accordingly. A methodology is presented for determining which surfaces are active at any given time based on the effective radius of curvature, coefficient of friction and displacement capacity of each sliding surface. The force-displacement relationships and relevant parameters of interest are subsequently derived based on the first principles.

This paper presents a methodology for localizing an autonomous tethered underwater robotic vehicle deployed for aquaculture inspection operations. The developed methodology is based on an Asynchronous Unscented Kalman Filer (UKF) to fuse information from onboard sensors along with a'priori knowledge about the aquaculture's geometry and the underwater robot's hydrodynamics. The performance of the proposed methodology is assessed through accuracy and consistency metrics generated from simulation benchmarks.

Jets coexist with planetary scale waves in the turbulence of planetary atmospheres. The coherent component of these structures arises from cooperative interaction between the coherent structures and the incoherent small-scale turbulence in which they are embedded. It follows that theoretical understanding of the dynamics of jets and planetary scale waves requires adopting the perspective of statistical state dynamics (SSD) which comprises the dynamics of the interaction between coherent and incoherent components in the turbulent state. In this work the S3T implementation of SSD for barotropic beta-plane turbulence is used to develop a theory for the jet/wave coexistence regime by separating the coherent motions consisting of the zonal jets together with a selection of large-scale waves from the smaller scale motions which constitute the incoherent component. It is found that mean flow/turbulence interaction gives rise to jets that coexist with large-scale coherent waves in a synergistic manner. Large-scale waves that would only exist as damped modes in the laminar jet are found to be transformed into exponentially growing waves by interaction with the incoherent small scale turbulence which results in a change in the mode structure allowing the mode to tap the energy of the mean jet. This mechanism of destabilization differs fundamentally and serves to augment the more familiar S3T instabilities in which jets and waves arise from homogeneous turbulence with energy source exclusively from the incoherent eddy field and provides further insight into the cooperative dynamics of the jet/waves coexistence regime in planetary turbulence., 22 pages, 15 figures

The peak deformation, acceleration, and the base shear experienced by the structures can be reduced by simulating yielding in an elastic system—also referred as apparent weakening. The negative stiffness device (NSD), used in this study, exhibits nonlinear-elastic negative stiffness behavior; by adding NSD to the elastic structure (primary structure), the resulting structure-device assembly behaves like a bilinear-elastic structure. In an elastic structure, the acceleration and base shear experienced by the structure can be reduced by adding the negative stiffness device, and the additional deformations caused from the reduced stiffness can be contained by adding viscous dampers. Previously, the authors have carried out experimental studies to demonstrate the effectiveness of apparent weakening in elastic structures, but little is known about the behavior of these systems when the primary structure itself yields. This paper focuses on the issues that may emanate with the addition of NSD to the sys...

This paper presents an innovative way in which university education can help pre-service teachers become better problem-solvers. The central idea is to use the “Technology Fair” as a means for promoting pre-service teachers pedagogical content knowledge about technological problem solving skills. This innovation is supported with results from a study carried out in autumn 2004. The purpose of the study was to investigate the influence of a procedure of working with primary school children to complete and present a technology fair project, on the educational value and meanings attached to problem solving skills by pre-service teachers. Pre-tests, mid-test and post-tests were administered to the pre-service teachers before, during, and after the preparation of the technology fair, respectively. A number of pre-service teachers were selected and interviewed after the completion of the technology fair. Data were also collected from reflective diaries kept by the pre-service teachers during the preparation phase of the technology fair. Analysis of the results indicates that the technology fair contributes to the development of positive values and attitudes in technology education and has a significant influence on improving pre-service teachers understanding and application of problem solving strategies within the domain of technology.

An analytical study of buildings without and with seismic damping systems was conducted to investigate the dynamic response of secondary systems. The buildings were represented by steel frames designed by the procedures described in the 2000 NEHRP Recommended Provisions. Nonlinear response analyses were performed for the undamped frames and the damped frames equipped with different energy dissipation systems and for far-field, near-field, and soft-soil earthquake histories. The study shows that significant benefits may be provided by viscous damping systems in terms of reduced floor spectral accelerations and floor absolute velocities.

The double concave Friction Pendulum (DCFP) bearing is an adaptation of the well-known single concave Friction Pendulum bearing. The principal benefit of the DCFP bearing is its capacity to accommodate substantially larger displacements compared to a traditional FP bearing of identical plan dimensions. Moreover, there is the capability to use sliding surfaces with varying radii of curvature and coefficients of friction, offering the designer greater flexibility to optimize performance. This paper describes the principles of operation of the bearing and presents the development of the force–displacement relationship based on considerations of equilibrium. The theoretical force–displacement relationship is then verified through characterization testing of bearings with sliding surfaces having the same and then different radii of curvature and coefficients of friction. Lastly, some practical considerations for analysis and design of DCFP bearings are presented. Copyright © 2006 John Wiley & Sons, Ltd.

Pseudomonas aeruginosa (PA) is a pathogenic gram‑negative bacterium that is widespread in nature, inhabiting soil, water, plants and animals. PA is a prevalent cause of deleterious human infections, particularly in patients whose host defense mechanisms have been compromised. Metabolomics is an important tool used to study host‑pathogen interactions and to identify novel therapeutic targets and corresponding compounds. The aim of the present study was to report the metabolic profile of live PA bacteria using in vivo high‑resolution magic angle spinning (HRMAS) nuclear magnetic resonance spectroscopy (NMR), in combination with 1‑ and 2‑dimensional HRMAS NMR. This methodology provides a new and powerful technique to rapidly interrogate the metabolome of intact bacterial cells and has several advantages over traditional techniques that identify metabolome components from disrupted cells. Furthermore, application of multidimensional HRMAS NMR, in combination with the novel technique total through‑Bond correlation Spectroscopy (TOBSY), is a promising approach that may be used to obtain in vivo metabolomics information from intact live bacterial cells and can mediate such analyses in a short period of time. Moreover, HRMAS 1H NMR enables the investigation of the associations between metabolites and cell processes. In the present study, we detected and quantified several informative metabolic molecules in live PA cells, including N‑acetyl, betaine, citrulline, alanine and glycine, which are important in peptidoglycan synthesis. The results provided a complete metabolic profile of PA for future studies of PA clinical isolates and mutants. In addition, this in vivo NMR biomedical approach might have clinical utility and should prove useful in gene function validation, the study of pathogenetic mechanisms, the classification of microbial strains into functional/clinical groups, the testing of anti‑bacterial agents and the determination of metabolic profiles of bacterial mutants.

In this paper, the efficiency of seismic isolation for seismic retrofitting of bridges with light superstructures and heavy substructures in the state of Illinois is studied. For this purpose, a representative bridge was selected by Illinois Department of Transpor- tation. A detailed structural model of the bridge capable of simulating the nonlinear behavior of its components and soil-bridge interaction effects was first constructed. Iterative multimode response spectrum analysis ~IMMRSA! of the bridge were conducted to assess its seismic vulnerability. The results from IMMRSA were also verified with nonlinear time history analyses. It was found that the bearings and substructures of the bridge need to be retrofitted. A conventional retrofitting technique was then adopted for the bridge and the cost of retrofit was estimated. Next, the existing bearings were replaced with seismic isolation bearings ~SIB! and the seismic analysis was repeated. It was found that SIB effectively mitigated the seismic forces and eliminated the need for retrofitting of the substructures. The cost of retrofitting using SIB was then calculated and found to be only 30% of the conventional retrofitting cost.

Isolation bearings experience tensile forces or uplift under certain conditions during seismic excitation. In general, this phenomenon is undesirable. This paper discusses an uplift prevention mechanism that uses prestress to develop sufficient compressive force on the isolator. A simplified theory of prestressed isolators is presented for three types of isolators, namely flat sliders, spherically shaped sliding bearings friction pendulum system (FPS), and elastomeric bearings. The behavior of prestressed isolators has been experimentally studied and presented. It has been observed that, consistent with the theory, the prestress has significant effects on the behavior of the prestressed isolators. The primary effect of prestress to increase the axial load on the isolators and prevent the uplift phenomenon was clearly observed in all three types of bearings tested in the study. The secondary effect of prestress to introduce additional lateral stiffness was also observed. While the additional axial load affects the behavior of elastomeric bearings, the effects were observed to be minor for the tested elastomeric bearings. In all cases of tested bearings, the experimental response could be predicted with sufficient accuracy by analytical means.

The entropic calibration of the risk-neutral density function is effective in recovering the strike dependence of options, but encounters difficulties in determining the relevant greeks. By use of put-call reversal we apply the entropic method to the time reversed economy, which allows us to obtain the spot price dependence of options and the relevant greeks.

The effect of near-field and soft-soil ground motions on structures with viscous damping systems was examined. Damping modification factors for damping ratios up to 100% of critical were obtained for sets of near-field and soft-soil ground motions and compared to the values presented in 2000 NEHRP Recommended Provisions. A study was carried out for the ductility demand in structures without and with damping systems, where the damped buildings were designed for a smaller base shear than conventional buildings in accordance with the 2000 NEHRP Provisions. Nonlinear response-history and simplified methods of the 2000 NEHRP Provisions were used to analyze single-degree-of-freedom systems and three-story moment frames with linear viscous and nonlinear viscous damping systems to acquire knowledge on the influence of near-field and soft-soil ground motions on the accuracy of simplified methods of analysis.

Equivalent lateral force and modal analysis procedures for yielding buildings with damping systems were developed, validated, and incorporated in the 2000 NEHRP Provisions. The technical basis for each procedure is described in the paper together with the simplifications adopted for inclusion in the Provisions. Procedures for calculating the effective damping and effective period and higher mode damping ratios for buildings equipped with yielding, viscoelastic, linear viscous, and nonlinear viscous damping devices are presented.

Installation of damping devices has been limited to diagonal or chevron brace configurations until the recent development of the toggle-brace configurations. These configurations magnify the effect of damping devices, thus facilitating their use in stiff framing systems. This paper introduces the scissor-jack-damper system that was developed as a variant of the togglebrace-damper systems, with the added advantage of compactness. The effectiveness of the scissor-jack configuration is demonstrated through testing of a large-scale steel-framed model structure on an earthquake simulator. Experiments showed that despite the small size of the damping device considered, the scissor-jack system provided a significant amount of damping and substantially reduced the seismic response of the tested structure. Response history and simplified analyses produce results that are consistent with the experimental results. [DOI: 10.1193/1.1540999]

A method based on the underlying principle of Value of Information analysis.For interventional and counterfactual Bayesian networks in forensic medical sciences.Examines whether interventional decision making is subject to amendments.Assesses what further information is worthwhile seeking prior to decision making. ObjectivesInspired by real-world examples from the forensic medical sciences domain, we seek to determine whether a decision about an interventional action could be subject to amendments on the basis of some incomplete information within the model, and whether it would be worthwhile for the decision maker to seek further information prior to suggesting a decision. MethodThe method is based on the underlying principle of Value of Information to enhance decision analysis in interventional and counterfactual Bayesian networks. ResultsThe method is applied to two real-world Bayesian network models (previously developed for decision support in forensic medical sciences) to examine the average gain in terms of both Value of Information (average relative gain ranging from 11.45% and 59.91%) and decision making (potential amendments in decision making ranging from 0% to 86.8%). ConclusionsWe have shown how the method becomes useful for decision makers, not only when decision making is subject to amendments on the basis of some unknown risk factors, but also when it is not. Knowing that a decision outcome is independent of one or more unknown risk factors saves us from the trouble of seeking information about the particular set of risk factors. Further, we have also extended the assessment of this implication to the counterfactual case and demonstrated how answers about interventional actions are expected to change when some unknown factors become known, and how useful this becomes in forensic medical science.

Zonal jets and non-zonal large-scale flows are often present in forced-dissipative barotropic turbulence on a beta-plane. The dynamics underlying the formation of both zonal and non-zonal coherent structures is investigated in this work within the statistical framework of Stochastic Structural Stability Theory (S3T). Previous S3T studies have shown that the homogeneous turbulent state undergoes a bifurcation at a critical parameter and becomes inhomogeneous with the emergence of zonal and/or large-scale non-zonal flows and that these statistical predictions of S3T are reflected in direct numerical simulations. In this paper, we study the dynamics underlying the S3T statistical instability of the homogeneous state as a function of parameters. It is shown that for weak planetary vorticity gradient, $\beta$, both zonal jets and non-zonal large-scale structures form from upgradient momentum fluxes due to shearing of the eddies by the emerging infinitesimal flow. For large $\beta$, the dynamics of the S3T instability differs for zonal and non-zonal flows but in both the destabilizing vorticity fluxes decrease with increasing $\beta$. Shearing of the eddies by the mean flow continues to be the mechanism for the emergence of zonal jets while non-zonal large-scale flows emerge from resonant and near resonant triad interactions between the large-scale flow and the stochastically forced eddies. The relation between the formation of large-scale structure through modulational instability and the S3T instability of the homogeneous state is also investigated and it is shown that the modulational instability results are subsumed by the S3T results., Comment: 22 pages, 15 figures, submitted to the Journal of the Atmospheric Sciences

S3T (Stochastic Structural Stability Theory) employs a closure at second order to obtain the dynamics of the statistical mean turbulent state. When S3T is implemented as a coupled set of equations for the streamwise mean and perturbation states, nonlinearity in the dynamics is restricted to interaction between the mean and perturbations. The S3T statistical mean state dynamics can be approximately implemented by similarly restricting the dynamics used in a direct numerical simulation (DNS) of the full Navier-Stokes equations (referred to as the NS system). Although this restricted nonlinear system (referred to as the RNL system) is greatly simplified in its dynamics in comparison to the associated NS, it nevertheless self-sustains a turbulent state in wall-bounded shear flow with structures and dynamics comparable to that in observed turbulence. Moreover, RNL turbulence can be analyzed effectively using theoretical methods developed to study the closely related S3T system. In order to better understand RNL turbulence and its relation to NS turbulence, an extensive comparison is made of diagnostics of structure and dynamics in these systems. Although quantitative differences are found, the results show that turbulence in the RNL system closely parallels that in NS and suggest that the S3T/RNL system provides a promising reduced complexity model for studying turbulence in wall-bounded shear flows., 18 pages, 14 figures

Energy dissipation systems are being increasingly employed in the United States to provide enhanced seismic protection for new and retrofit building and bridge construction. The hardware utilized includes yielding steel devices, friction devices, viscoelastic solid devices, and mostly, so far, fluid viscous devices. This hardware has been used in either diagonal or chevron brace configurations. This paper presents three new configurations that utilize toggle-brace mechanisms to substantially magnify the effect of damping devices so that they can be utilized effectively in applications of small structural drift. Shake table testing of a large scale steel model structure and analysis are used to demonstrate the utility of these configurations. The experimental results demonstrate substantial increases in the damping ratio despite the use of small size damping devices, and, accordingly, significant attenuation of the seismic response of the tested stiff structure is observed. Moreover, the experimental resul...

Seismic protection techniques are seismic design and construction strategies for mitigating the damaging effects of earthquakes on structures through the introduction of flexibility and/or energyabsorption capability within the structural system. These techniques involve the use of a special seismic protective system. The objective of adding the seismic protective system to new or the existing construction is to deflect earthquake-induced energy away from the structure and/or dissipate part of the earthquake-induced energy in elements not forming part of the gravity framing system. Key to this technique is limiting or eliminating inelastic action and damage to the gravityload-resisting system, reduction of forces for the design of the foundation and, under certain conditions, reductions of accelerations and protection of non-structural systems. Seismic protective systems include seismic isolation, damping systems, adaptive systems, self-centering systems, active and semi-active systems and combinations of these, although so far only seismic isolation and damping systems have found widespread implementation and acceptance by the profession. The origins of seismic protective systems may be traced to antiquity. The rocking columns of fourth century B.C. Greek temples and the sliding foundations of sixteenth century Islamic minarets in Asia are primitive but apparently effective seismic protective systems. The first documented example of a seismic protective system is the 1870 patent of Jules Touaillon of San Francisco for a strikingly modern seismic isolation system (the paper of Chang and Spencer in this issue utilizes this isolator in a modern active system). With a history of 140 years, some seismic protective systems have now reached the stage of widespread acceptance and implementation. Yet new systems are continuously proposed and studied, with a particular emphasis on active, semi-active and adaptive systems. In addition, studies concentrate on understanding the lifetime behavior and properties, in the advanced modeling of the mechanical behavior, in improving the reliability and in developing techniques for testing of seismic protective system hardware. The latter studies reflect the increasing number of implementation of these techniques in critical structures (e.g., hospitals and important bridges), in extreme multi-hazard environments (e.g., arctic conditions and offshore applications) and in extreme load and displacement demand applications (e.g., isolators of load-carrying capacity exceeding 150MN and of displacement capacity exceeding 1m have been implemented).

92 patients with temporal lobe epilepsy (TLE) were classified into reading deficient (RD; N = 41) and non-reading deficient (no-RD; N = 51) groups. A cutoff of 80 was used to further classify patients as having low average or better (AVG: IQ > 79) or below average (LOW: 69 < IQ < 80) intellectual ability. Differences between RD-AVG and no-RD-AVG patients in profiles of performance on cognitive tests were specific to verbal and non-verbal memory and verbal abilities, but not visuoconstructional and executive abilities. RD-LOW patients exhibited globally reduced abilities. Profiles of performance on cognitive tests were sensitive to side of seizure onset in the no-RD AVG group, but not the RD-AVG or RD-LOW groups. These data suggest that a group of patients with TLE and reduced academic achievement exhibit cognitive deficits suggestive of a language learning disability, and that cognitive tests are less sensitive to side of seizure onset in this group.

Object. In this paper the authors demonstrate the concordance between magnetic source (MS) imaging and direct cortical stimulation for mapping receptive language cortex.Methods. In 13 consecutive surgical patients, cortex specialized for receptive language functions was identified noninvasively by obtaining activation maps aided by MS imaging in the context of visual and auditory word-recognition tasks. Surgery was then performed for treatment of medically intractable seizure disorder (eight patients), and for resection of tumor (four), or angioma (one). Mapping of language areas with cortical stimulation was performed intraoperatively in 10 patients and extraoperatively in three. Cortical stimulation mapping verified the accuracy of the MS imaging—based localization in all cases.Conclusions. Information provided by MS imaging can be especially helpful in cases of atypical language representation, including bihemispheric representation, and location of language in areas other than those expected within the dominant hemisphere, such as the anterior portion of the superior temporal gyrus, the posteroinferior portion of the middle temporal gyrus, the basal temporal cortex, and the lateral temporooccipital cortex.

A concise review of both classical and quantum theories of electromagnetism is given, with emphasis on the degree of equivalence between the theories. The significance of gauge constraints in quantum theory is discussed in detail, as is the role of the gauge in restoring Maxwell's theory in the classical limit. Results are presented which make explicit the effect of these gauge constraints for different formulations of the quantised theory. These results are applied to the problem of quantising the electrostatic field in a parallel plate capacitor. It is shown how the electrostatic field can be understood in terms of the average behaviour of a system of moving photons.

An 18-year-old left-handed female with a large left hemisphere arteriovenous malformation in the frontoparietal region underwent brain mapping of the somatosensory cortex using a whole-head neuromagnetometer. Results indicated the presence of two complete somatosensory maps in the unaffected, right hemisphere. A map of contralateral body surface areas was found in the expected location in the anterior parietal lobe. A second map of ipsilateral body surface areas was found inferior to the first, extending from the inferior parietal lobe into peri-insular cortex, including SII. A less topographically organized map of the right side of the body was also found in the left hemisphere. Evoked magnetic flux components associated with right-sided stimulation occurred earlier, were more numerous, and were stronger in the ipsilateral as compared to the contralateral hemisphere, suggesting that the ipsilateral map is functional. These findings are discussed in relationship to other functional imaging studie...

Summary: Purpose: To determine the efficacy and relative contribution of several diagnostic methods [ictal and interictal scalp and intracranial EEG, magnetic resonance imaging (MRI), and magnetoencephalography (MEG)] in identifying the epileptogenic zone for resection. Methods: This was a prospective study using a masked comparison-to-criterion standard. Fifty-eight consecutive patients with refractory partial epilepsy from two university comprehensive epilepsy programs were studied. Patients who were evaluated for and underwent epilepsy surgery were recruited. The main outcome measure was the efficacy of each diagnostic method to identify the resected epileptogenic zone, when referenced to surgical outcome. Results: MEG (52%) was second only to ictal intracranial V-EEG in predicting the epileptogenic zone for the entire group of patients who had an excellent surgical outcome (seizure free or rare seizure). In a subanalysis, for patients who had temporal lobe surgery, this same relation was seen (MEG, 57%, ictal intracranial V-EEG, 62%). With extratemporal resection, ictal (81%) and interictal (75%) intracranial EEG were superior to MEG (44%) in predicting the surgery site in those patients with an excellent outcome. Finally, for all patients who had a good surgical outcome, MEG (52%) was better than ictal (33%) or interictal (45%) scalp VEEG in predicting the site of surgery. Conclusions: These results indicate that MEG is a very promising diagnostic method and raise the possibility that it may obviate the need for invasive EEG in some cases or reduce the length of scalp EEG evaluation in others.

As passive structural control systems begin to see an increased acceptance within the earthquake engineering community, strong research efforts have been shifted towards the development of semi-active structural control systems. To place semi-active control systems within a proper frame of reference, this paper begins with a qualitative description and comparison of passive, active, and semi-active control systems for protecting structures subjected to earthquake induced ground motion. A detailed literature review of semi-active control systems is then provided which provides references to both theoretical and experimental research but concentrates on describing the results of experimental work. Specifically, the review focuses on descriptions of the dynamic behavior and distinguishing features of various systems which have been experimentally tested both at the component level and within small-scale structural models. The semi-active systems which are reviewed include stiffness control devices, electrorheological dampers, magnetorheological dampers, friction control devices, fluid viscous dampers, tuned mass dampers and tuned liquid dampers. The review clearly demonstrates that semi-active control devices have the potential for improving the seismic behavior of full-scale civil structures.

New static and dynamic displacement-based procedures have been developed by the Federal Emergency Management Agency (FEMA) for the seismic evaluation and design of buildings. The static procedures calculate displacements in yielding buildings as the product of an elastic spectral displacement and coefficients Ci. Mean elastic and mean inelastic displacements are assumed to be equal for elastic periods, T0, greater than the characteristic site period, Tg. The data presented in this paper and elsewhere support this assumption for values of the strength ratio greater than or equal to 0·20. For T0 ≤ Tg, mean inelastic displacements can substantially exceed mean elastic displacements for all values of the strength ratio; FEMA 273 accounts for this observation by the coefficient C1. However, the FEMA 273 cap on C1 (= 1·5) is not sufficiently conservative and should be increased to 3·0 for the analysis and design of modern construction. The effects of stiffness degradation, strength deterioration and pinching are represented in FEMA 273 by the coefficient C2. The values assigned to C2 appear to be most reasonable. Nonlinear dynamic analysis is being widely used to estimate maximum deformations and displacements in buildings. The values calculated for the maximum deformations and displacements will be dependent upon the means used to characterize structural damping in the building frame. Although structural damping is routinely implemented through a damping constant (or matrix), such an implementation will overestimate the effects of structural damping in a yielding building and underestimate maximum deformations and displacements. Structural damping should be characterized by the target damping ratio (typically 5% of critical) at the point of maximum displacement. Copyright © 1999 John Wiley & Sons, Ltd.