bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral mapping tools from the earth sciences applied to spectral microscopy data
Authors: Harris A. Thomas
Published: September 2006

Background:

Spectral imaging, originating from the field of earth remote sensing, is a powerful tool that is being increasingly used in a wide variety of applications for material identification. Several workers have used techniques like linear spectral unmixing (LSU) to discriminate materials in images derived from spectral microscopy. However, many spectral analysis algorithms rely on assumptions that are often violated in microscopy applications. This study explores algorithms originally developed as improvements on early earth imaging techniques that can be easily translated for use with spectral microscopy.

Methods:

To best demonstrate the application of earth remote sensing spectral analysis tools to spectral microscopy data, earth imaging software was used to analyze data acquired with a Leica confocal microscope with mechanical spectral scanning. For this study, spectral training signatures (often referred to as endmembers) were selected with the ENVI (ITT Visual Information Solutions, Boulder, CO) “spectral hourglass” processing flow, a series of tools that use the spectrally over‐determined nature of hyperspectral data to find the most spectrally pure (or spectrally unique) pixels within the data set. This set of endmember signatures was then used in the full range of mapping algorithms available in ENVI to determine locations, and in some cases subpixel abundances of endmembers.

Results:

Mapping and abundance images showed a broad agreement between the spectral analysis algorithms, supported through visual assessment of output classification images and through statistical analysis of the distribution of pixels within each endmember class.

Conclusions:

The powerful spectral analysis algorithms available in COTS software, the result of decades of research in earth imaging, are easily translated to new sources of spectral data. Although the scale between earth imagery and spectral microscopy is radically different, the problem is the same: mapping material locations and abundances based on unique spectral signatures. © 2006 International Society for Analytical Cytology
Aged mice exhibit distinct peripheral B‐cell phenotypes differing in apoptotic susceptibility: An ex vivo analysis
Authors: Verdier Mireille , Malissein Emilie , Munteanu Eliza , Jayat‐Vignoles Chantal , Ratinaud Marie‐Hélène , Troutaud Danielle
Published: September 2006

Background:

Age‐related changes in the antibody response have been classically associated with alterations in T‐cell help, but increasing evidence shows that intrinsic B‐cell defects exist. This article analyzes the apoptotic susceptibility of peripheral B‐cells in aged and young control mice.

Materials and Methods:

Freshly isolated lymphocytes from spleen and Peyer's patches (PPs) were labeled for B‐cell lineage (B220+ cells) and germinal center B subset (GCs, B220+/PNA+ cells). Alternatively, splenic B‐cells purified by MACS were used. Apoptosis was monitored by the Annexin V binding, incorporation of 3,3′‐dihexyloxacarbocyanine iodide (DiOC6(3)), propidium iodide (PI) staining, and morphological changes. Moreover, intracellular Bcl‐2 expression and Bad phosphorylation status were also analyzed in B‐cells.

Results:

We showed in aging mice an enhanced Annexin V+/PI− cell percentage in splenic B‐lymphocytes, which was correlated with a lower ΔΨm. By contrast, no change in apoptosis was observed in compartments known to be enriched in activated B‐cells (GCs and PPs). Analysis of Bcl‐2 levels revealed no modification. When using B‐cells purified by MACS, we strongly confirm data obtained on staining cells. Moreover, enhanced spontaneous apoptosis of splenic B‐cells in aged mice was found to be correlated with a reduced phosphorylated Bad expression.

Conclusion:

Increased apoptosis of resting B‐cells in old mice may be determined by an altered Bad phosphorylation, which in turn contributes to cell death by lowering the mitochondrial threshold for apoptosis. © 2006 International Society for Analytical Cytology
Spectral imaging: Principles and applications
Authors: Garini Yuval , Young Ian T. , McNamara George
Published: September 2006

Background:

Spectral imaging extends the capabilities of biological and clinical studies to simultaneously study multiple features such as organelles and proteins qualitatively and quantitatively. Spectral imaging combines two well‐known scientific methodologies, namely spectroscopy and imaging, to provide a new advantageous tool. The need to measure the spectrum at each point of the image requires combining dispersive optics with the more common imaging equipment, and introduces constrains as well.

Methods and Results:

The principles of spectral imaging and a few representative applications are described. Spectral imaging analysis is necessary because the complex data structure cannot be analyzed visually. A few of the algorithms are discussed with emphasis on the usage for different experimental modes (fluorescence and bright field). Finally, spectral imaging, like any method, should be evaluated in light of its advantages to specific applications, a selection of which is described.

Conclusions:

Spectral imaging is a relatively new technique and its full potential is yet to be exploited. Nevertheless, several applications have already shown its potential. © 2006 International Society for Analytical Cytology
DNA methylation in stingless bees with low and high heterochromatin contents as assessed by restriction enzyme digestion and image analysis
Authors: Mampumbu André R. , Mello Maria Luiza S.
Published: September 2006

Background:

The stingless bee genus Melipona has been divided into two groups, based on their heterochromatin content. Melipona quadrifasciata and Melipona rufiventris have low and high levels of heterochromatin, respectively. Since condensed chromatin may be rich in methylated DNA sequences, M. quadrifasciata and M. rufiventris nuclei may contain different amounts of methylated CpG. These differences could be assessed by comparing Feulgen‐DNA values obtained by image analysis of cells treated with the restriction enzymes Msp I and Hpa II that distinguish between methylated and unmethylated DNA. Msp I and Hpa II cleave the sequence ‐CCGG‐, but there is no cleavage by Hpa II if the cytosine of the central CG dinucleotide is methylated.

Methods:

Malpighian tubules of M. quadrifasciata and M. rufiventris were treated with Msp I and Hpa II prior to the Feulgen reaction, and analyzed by automatic scanning microspectrophotometry.

Results:

The Feulgen‐DNA values for the heterochromatin of M. rufiventris and for the small heterochromatin and some euchromatin domains of M. quadrifasciata mostly decreased after treatment with Msp I, but were unchanged after treatment with Hpa II.

Conclusion:

CpG methylation, although detected in diverse chromatin compartments in different bee species, may induce silencing effects required for the same cell physiology. © 2006 International Society for Analytical Cytology
Confocal laser scanning microscopy of whole mouse ovaries: Excellent morphology, apoptosis detection, and spectroscopy
Authors: Zucker Robert M. , Jeffay Susan C.
Published: September 2006

Background:

Ovaries consist of numerous follicles, oocytes, and granulosa cells in different stages of development. Many of these follicles will undergo an apoptotic process during the lifetime of the animal. By using proper tissue preparation methods, the events within the whole ovary can be observed by using 3D confocal microscopy.

Methods:

Whole ovaries were stained with LysoTracker Red (LT), fixed with 4% paraformaldehyde (PF) and 1% glutaraldehyde (Glut), dehydrated with methanol (MEOH), and cleared with benzyl alcohol and benzyl benzoate (BABB). Using this tissue preparation technique, the ovary becomes relatively transparent, allowing its morphology to be observed with confocal microscopes. A spectral imaging system (PARISS) located on a conventional microscope was used to interpret the LT dye spectra and fixation products in the tissues with different excitation wavelengths.

Results:

Apoptosis in the follicle was detected as clusters of intensely stained granulosa cells located in close proximity to the oocytes. The fixation with Glut and PF preserved morphological details, increased tissue fluorescence, thus increased the signal to noise of the background image.

Conclusions:

Thick tissues can be imaged after they are properly stained, aldehyde fixed, and BABB cleared. LT intensely stained single cells or clusters of apoptotic cells in the follicles and the nucleolus. Spectral differences between LT as an indicator of apoptosis and Glut‐PF fixation was used to visualize ovarian morphology and apoptosis. The PARISS spectrophotometer revealed spectral peaks for LT at 609.6 nm and for Glut‐PF at 471.3 nm. The proper use of the spectra from these fluorescence molecules is the foundation for high quality morphological images of apoptosis. By sequentially imaging the two probes with a 488 nm laser and a 543/568 nm laser, there was a reduction in fluorescent cross talk and an increase in image quality. © 2006 International Society for Analytical Cytology
Increasing lanthanide luminescence by use of the RETEL effect
Authors: Leif Robert C. , Vallarino Lidia M. , Becker Margie C. , Yang Sean
Published: September 2006

Background:

Luminescent lanthanide complexes produce emissions with the narrowest‐known width at half maximum; however, their significant use in cytometry required an increase in luminescence intensity. The companion review, Leif et al., Cytometry 2006;69A:767–778, described a new technique for the enhancement of lanthanide luminescence, the Resonance Energy Transfer Enhanced Luminescence (RETEL) effect, which increases luminescence and is compatible with standard slide microscopy.

Methods:

The luminescence of the europium ion macrocyclic complex, EuMac, was increased by employing the RETEL effect. After adding the nonluminescent gadolinium ion complex of the thenoyltrifluoroacetonate (TTFA) ligand or the sodium salt of TTFA in ethanol solution, the EuMac‐labeled sample was allowed to dry. Both a conventional arc lamp and a time‐gated UV LED served as light sources for microscopic imaging. The emission intensity was measured with a CCD camera. Multiple time‐gated images were summed with special software to permit analysis and effective presentation of the final image.

Results:

With the RETEL effect, the luminescence of the EuMac‐streptavidin conjugate increased at least six‐fold upon drying. Nuclei of apoptotic cells were stained with DAPI and tailed with 5BrdUrd to which a EuMac‐anti‐5BrdU conjugate was subsequently attached. Time‐gated images showed the long‐lived EuMac luminescence but did not show the short‐lived DAPI fluorescence. Imaging of DNA‐synthesizing cells with an arc lamp showed that both S phase and apoptotic cells were labeled, and that their labeling patterns were different. The images of the luminescent EuMac and fluorescent DAPI were combined to produce a color image on a white background. This combination of simple chemistry, instrumentation, and presentation should make possible the inexpensive use of the lanthanide macrocycles, Quantum Dyes®, as molecular diagnostics for cytological and histopathological microscopic imaging. © 2006 International Society for Analytical Cytology
Single particle high resolution spectral analysis flow cytometry
Authors: Goddard Gregory , Martin John C. , Naivar Mark , Goodwin Peter M. , Graves Steven W. , Habbersett Robb , Nolan John P. , Jett James H.
Published: September 2006

Background:

While conventional multiparameter flow cytometers have proven highly successful, there are several types of analytical measurements that would benefit from a more comprehensive and flexible approach to spectral analysis including, but certainly not limited to spectral deconvolution of overlapping emission spectra, fluorescence resonance energy transfer measurements, metachromic dye analysis, free versus bound dye resolution, and Raman spectroscopy.

Methods:

Our system utilizes a diffraction grating to disperse the collected fluorescence and side‐scattered light from cells or microspheres passing through the interrogation region over a rectangular charge‐coupled‐device image sensor. The flow cell and collection optics are taken from a conventional flow cytometer with minimal modifications to assure modularity of the system.

Results:

Calibration of the prototype spectral analysis flow cytometer included wavelength characterization and calibration of the dispersive optics. Benchmarking of the system demonstrated a single particle/cell intensity sensitivity of 2160 MESF of R‐Phycoerythrin. Single particle spectra taken with our instrument were validated against bulk solution fluorimeter and conventional flow cytometer measurements. Coefficients of variation of integrated spectral fluorescence intensity of several sets of standard fluorescent microspheres ranged from 1.4 to 4.8% on the spectral system. Spectral discrimination of free versus PI bound to cells is also demonstrated.

Conclusions:

It is demonstrated that the flow spectrometer has sufficient sensitivity and wavelength resolution to detect single cells and microspheres, including multi‐fluorophore labeled microspheres. The capability to use both standard mathematical deconvolution techniques for data analysis, coupled with the feasibility of integration with existing flow cytometers, will improve the accuracy and precision of ratiometric measurements, enable the analysis of more discrete emission bands within a given wavelength range, and allow more precise resolution of the relative contribution of individual fluorophores in multiply‐tagged samples, thereby enabling a range of new applications involving the spectral analysis of single cells and particles. © 2006 International Society for Analytical Cytology
Increasing the luminescence of lanthanide complexes
Authors: Leif Robert C. , Vallarino Lidia M. , Becker Margie C. , Yang Sean
Published: September 2006

This review compares the chemical and physical properties of lanthanide ion complexes and of other narrow‐emitting species that can be used as labels for cytometry. A series of luminescent lanthanide ion macrocyclic complexes, Quantum Dyes®, which do not release or exchange their central lanthanide ion, do accept energy transfer from ligands, and are capable of covalent binding to macromolecules, including proteins and nucleic acids, is described and their properties are discussed.

Two methods are described for increasing the luminescence intensity of lanthanide ion complexes, which intrinsically is not as high as that of standard fluorophores or quantum dots. One method consists of adding a complex of a second lanthanide ion in a micellar solution (columinescence); the other method produces dry preparations by evaporation of a homogeneous solution containing an added complex of a second lanthanide ion or an excess of an unbound antenna ligand. Both methods involve the Resonance Energy Transfer Enhanced Luminescence, RETEL, effect as the mechanism for the luminescence enhancement. © 2006 International Society for Analytical Cytology
Factors affecting flow karyotype resolution
Authors: Ng Bee Ling , Carter Nigel P.
Published: September 2006

Background:

One of the major factors which influences the chromosome purity achievable particularly during high speed sorting is the analytical resolution of individual chromosome peaks in the flow karyotype, as well as the amount of debris and fragmented chromosomes. We have investigated the factors involved in the preparation of chromosome suspensions that influence karyotype resolution.

Methods:

Chromosomes were isolated from various human and animal cell types using a series of polyamine buffer isolation protocols modified with respect to pH, salt concentration, and chromosome staining time. Each preparation was analyzed on a MoFlo sorter (DAKO) configured for high speed sorting and the resolution of the flow karyotypes compared.

Results:

High resolution flow cytometric data was obtained with chromosomes optimally isolated using hypotonic solution buffered at pH 8.0 and polyamine isolation buffer (with NaCl excluded) between pH 7.50 and 8.0. Extending staining time to more than 8 h with chromosome suspensions isolated from cell lines subjected to sufficient metaphase arrest times gave the best result with the lowest percentage of debris generated, tighter chromosome peaks with overall lower coefficients of variation, and a 1‐ to 5‐fold increase in the yield of isolated chromosomes.

Conclusions:

Optimization of buffer pH and the length of staining improved karyotype resolution particularly for larger chromosomes and reduced the presence of chromosome fragments (debris). However, the most interesting and surprising finding was that the exclusion of NaCl in PAB buffer improved the yield and resolution of larger chromosomes. © 2006 International Society for Analytical Cytology
Syringe pumped high speed flow cytometry of oceanic phytoplankton
Authors: Zubkov Mikhail V. , Burkill Peter H.
Published: September 2006

Background:

Nanophytoplankton (2–20 μm) are less numerous than picophytoplankton (<2 μm) in the oceans but their biomass and production are comparable and sometimes higher. The accuracy of cytometry‐based enumeration of phytoplankton ultimately depends on cell abundance and sample flow rate. Commercial flow cytometers in which sheath and core streams are driven by air pressure cannot produce sufficiently high, stable sample flow rate. The present study demonstrates the applicability of a syringe pump for flow cytometric enumeration of oceanic nanophytoplankton on two meridional transects across the Atlantic Ocean.

Methods:

Commercially available syringe pumps were used to deliver live phytoplankton samples into a flow cell of standard flow cytometers (FACSort, FACSCalibur, BD) with increased flow rate of > 1.0 ml min−1 compared to the normal air pressure sample delivery of < 0.1 ml min−1. An auxiliary application of syringe pump flow cytometry for calibrating 0.5 μm bead concentration standards is also discussed.

Results:

The results demonstrated that flow cytometry of samples injected at rates above 0.1 ml min−1 is achievable and worthwhile. Counts of phytoplankton in air and syringe pumped samples agreed closely. Syringe pumping of samples offered a broader range of flow rates up to 0.8–1.0 ml min−1 without detrimental effect on flow cytometric enumeration of cells. The increased number of coincidences at high flow rates led to an approximate 10% decrease of Cyanobacteria counts when the acquisition rate approached 1,000 particles s−1, but seemed to have a lesser effect on counting rarer phytoplankton. The syringe pump flow cytometry allowed enumeration of phytoplankton groups at concentrations of 5–100 cells ml−1, cell concentrations equivalent to those of Cyanobacteria in the twilight deep ocean.

Conclusion:

The proposed syringe pump modification of a FACS instrument represents a significant improvement for accurate enumeration of the less abundant phytoplankton and so gives better estimations of phytoplankton distribution and standing stocks. © 2006 International Society for Analytical Cytology
Synthesis of New Phenanthroline‐Based Heteroditopic Ligands – Highly Efficient and Selective Fluorescence Sensors for Copper(II) Ions
Authors: Comba Peter , Krämer Roland , Mokhir Andriy , Naing Kyaw , Schatz Erik
Published: September 2006

The heteroditopic phenanthroline derivatives 5,6‐bis(2‐pyridylcarboxamido)‐1,10‐phenanthroline (H2L1) and 5,6‐bis[(4‐methoxy‐2‐pyridyl)carboxamido]‐1,10‐phenanthroline (H2L2) have been prepared and characterized, together with their luminescent ruthenium(II) complexes [Ru(bpy)2(H2L1,2)](PF6)2 and [Ru(H2L1)3](PF6)2 and the corresponding iron(II) complex [Fe(H2L1)3](PF6)2. In these complexes, the metal ion is coordinated by the bidentate phen site of H2L. The luminescence of the ruthenium complexes (λex = 450 nm, λem ca. 620 nm) is completely quenched by Cu2+ ions in the micromolar concentration range and, to a lesser extent, by other metal ions. At pH 5, the response of the luminescent sensors is highly Cu2+‐selective. Heterodinuclear complexes [Ru(bpy)2(LM)](PF6)2, [Ru(LM)3](PF6)2, and [Fe(LM)3](PF6)2 have been isolated for M = Cu2+, Ni2+, Co2+, and Pd2+. It is suggested that M is coordinated to the tetradentate N4 site of L by two deprotonated amide N atoms and two pyridyl groups. This coordination type is confirmed by the EPR spectrum of the compound [RuII(bpy)2(L1CuII)](PF6)2.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Torsional balance of plan‐asymmetric structures with frictional dampers: experimental results
Authors: Vial Ignacio J. , de la Llera Juan C. , Almazán José L. , Ceballos Víctor
Published: September 2006

This investigation deals with the measured seismic response of a six‐storey asymmetric structural model with frictional dampers. Its main objective is to experimentally prove the concept of weak torsional balance for mass‐ and stiffness‐eccentric model configurations. The goal is to control the torsional response of these asymmetric structures and to achieve, if possible, a weak form of torsional balance by placing the so‐called empirical centre of balance (ECB) of the structure at equal distance from the edges of the building plan. The control of the dynamic response of asymmetric structures is investigated herein by using steel–teflon frictional dampers. As expected from theory, experimental results show that the mean‐square and peak displacement demand at the flexible and stiff edges of the plan may be similar in magnitude if the dampers are optimally placed. Frictional dampers have proven equally effective in controlling lateral‐torsional coupling of torsionally flexible as well as stiff structures. On the other hand, it is shown that impulsive ground motions require larger frictional capacities to achieve weak torsional balance. Copyright © 2006 John Wiley & Sons, Ltd.
Yielding oscillator subjected to simple pulse waveforms: numerical analysis & closed‐form solutions
Authors: Mylonakis George , Voyagaki Elia
Published: September 2006

Numerical and analytical solutions are presented for the elastic and inelastic response of single‐degree‐of‐freedom yielding oscillators to idealized ground acceleration pulses. These motions are typical of near‐fault earthquake recordings generated by forward rupture directivity and may inflict damage in the absence of substantial structural strength and ductility capacity. Four basic pulse waveforms are examined: (1) triangular; (2) sinusoidal; (3) exponential; and (4) rectangular. In the first part of the article, a numerical study is presented of the effect of oscillator period, strength, damping, post‐yielding stiffness and number of excitation cycles, on inelastic response. Results are presented in the form of dimensionless graphs and regression formulas that elucidate the salient features of the problem. It is shown that conventional R–µ relations may significantly underestimate ductility demand imposed by near‐fault motions.

The second part of the article concentrates on elastic‐perfectly plastic oscillators. Closed‐form solutions are derived for post‐yielding response and associated ductility demand. It is shown that all three ground motion histories (i.e. acceleration, velocity, and displacement) control oscillator response—contrary to the widespread view that ground velocity alone is of leading importance. The derived solutions provide insight on the physics of inelastic response, which is often obscured by the complexity of numerical algorithms and actual earthquake motions. The model is evaluated against numerical results from near‐field recordings. A case study is presented. Copyright © 2006 John Wiley & Sons, Ltd.
Rigid‐plastic seismic design of reinforced concrete structures
Authors: Domingues Costa J. L. , Bento R. , Levtchitch Vsevolod , Nielsen M. P.
Published: September 2006

In this paper a new seismic design procedure for Reinforced Concrete (R/C) structures is proposed—the Rigid‐Plastic Seismic Design (RPSD) method. This is a design procedure based on Non‐Linear Time‐ History Analysis (NLTHA) for systems expected to perform in the non‐linear range during a lifetime earthquake event. The theoretical background is the Theory of Plasticity (Rigid‐Plastic Structures).

Firstly, a collapse mechanism is chosen and the corresponding stress field is made safe outside the regions where plastic behaviour takes place. It is shown that this allows the determination of the required structural strength with respect to a pre‐defined performance parameter using a rigid‐plastic response spectrum, which is characteristic of the ground motion alone. The maximum strength demand at any point is solely dependent on the intensity of the ground motion, which facilitates the task of distributing required strength throughout the structure.

Any artificial considerations intended to adjust results according to empirical observations are avoided, which, from a conceptual point of view, is considered to be an advantage over other simplified design procedures for seismic design.

The procedure is formulated using a step‐by‐step format followed by a design example of a 4‐storey‐R/C‐plane‐frame. Results are compared with refined NLTHA and found to be extremely encouraging. Copyright © 2006 John Wiley & Sons, Ltd.
Re‐shaping hysteretic behaviour—spectral analysis and design equations for semi‐active structures
Authors: Rodgers Geoffrey W. , Mander John B. , Geoffrey Chase J. , Mulligan Kerry J. , Deam Bruce L. , Carr Athol
Published: September 2006

Semi‐active dampers offer significant capability to reduce dynamic wind and seismic structural response. A novel resetable device with independent valve control laws that enables semi‐active re‐shaping of the overall structural hysteretic behaviour has been recently developed, and a one‐fifth scale prototype experimentally validated. This research statistically analyses three methods of re‐shaping structural hysteretic dynamics in a performance‐based seismic design context. Displacement, structural force, and total base‐shear response reduction factor spectra are obtained for suites of ground motions from the SAC project. Results indicate that the reduction factors are suite invariant. Resisting all motion adds damping in all four quadrants and showed 40–60% reductions in the structural force and displacement at the cost of a 20–60% increase in total base‐shear. Resisting only motion away from equilibrium adds damping in quadrants 1 and 3, and provides reductions of 20–40%, with a 20–50% increase in total base‐shear. However, only resisting motion towards equilibrium adds damping in quadrants 2 and 4 only, for which the structural responses and total base‐shear are reduced 20–40%. The spectral analysis results are used to create empirical reduction factor equations suitable for use in performance based design methods, creating an avenue for designing these devices into structural applications. Overall, the reductions in both response and base‐shear indicate the potential appeal of this semi‐active hysteresis sculpting approach for seismic retrofit applications—largely due to the reduction of the structural force and overturning demands on the foundation system. Copyright © 2006 John Wiley & Sons, Ltd.
Earthquake fault rupture—shallow foundation interaction in undrained soils: a simplified analytical approach
Authors: Tolga Yilmaz M. , Paolucci Roberto
Published: September 2006

The interaction between normal or reverse fault ruptures and shallow foundations resting on a homogeneous undrained soil layer is investigated. After performing a thorough set of non‐linear finite element simulations, three simple kinematic mechanisms are proposed to predict the conditions for the fault rupture to be diverted by the foundation. The results obtained by both numerical and analytical approaches are in good agreement, and support the adequacy of the proposed mechanisms.

A relationship is established for assessing the minimum foundation bearing load needed for diversion of the fault rupture trace, either normal or reverse. This relationship is proved to be independent of the fault type and dip angle, so that it can be applied easily for engineering applications, even in the absence of specific tectonic information. Copyright © 2006 John Wiley & Sons, Ltd.
Real‐time hybrid experiments with Newmark integration, MCSmd outer‐loop control and multi‐tasking strategies
Authors: Bonnet P. A. , Lim C. N. , Williams M. S. , Blakeborough A. , Neild S. A. , Stoten D. P. , Taylor C. A.
Published: September 2006

Real‐time hybrid testing is a promising technique for experimental structural dynamics, in which the structure under consideration is split into a physical test of key components and a numerical model of the remainder. The physical test and numerical analysis proceed in parallel, in real time, enabling testing of critical elements at large scale and at the correct loading rate. To date most real‐time hybrid tests have been restricted to simple configurations and have used approximate delay compensation schemes. This paper describes a real‐time hybrid testing approach in which non‐linearity is permitted in both the physical and numerical models, and in which multiple interfaces between physical and numerical substructures can be accommodated, even when this results in very stiff coupling between actuators. This is achieved using a Newmark explicit numerical solver, an advanced adaptive controller known as MCSmd and a multi‐tasking strategy. The approach is evaluated through a series of experiments on discrete mass–spring systems. Copyright © 2006 John Wiley & Sons, Ltd.
A semi‐analytic approach to retrieve the unitary impulse response function
Authors: Chen Kui‐Fu , Zhang Sen‐Wen
Published: September 2006

Two kinds of errors occur in numerically transforming the transfer function (TF) to the unitary impulse response function (UIRF), the truncating error due to ignoring high frequency band contribution, and the discrete error due to numerical integration. The truncating error becomes prevailing if the TF attenuating trend is slow as the frequency approaches infinity. A semi‐analytic approach is presented to alleviate this error. This approach dissects the whole frequency axis symmetrically into three bands, the central band, and two side bands extending to infinity. The contribution from the central band is calculated numerically, while the TF over the side bands is approximated as a simple function with an explicitly known inverse Laplace transform. This approach can overcome the Gibbs oscillation in computing the UIRF for a slowly attenuating TF, as is verified by the numerical examples studied here. Copyright © 2006 John Wiley & Sons, Ltd.
Shaking table model test on Shanghai World Financial Center Tower
Authors: Lu Xilin , Zou Yun , Lu Wensheng , Zhao Bin
Published: September 2006

The height of 101‐storey Shanghai World Financial Center Tower is 492m above ground making it possible the tallest building in the world when completed. Three parallel structural systems including mega‐frame structure, reinforced concrete and braced steel services core and outrigger trusses, are combined to resist vertical and lateral loads. The building could be classified as a vertically irregular structure due to a number of stiffened and transfer stories in the building. Complexities related to structural system layout are mainly exhibited in the design of services core, mega‐diagonals and outrigger trusses. According to Chinese Code, the height 190 m of the building clearly exceeds the stipulated maximum height of for a composite frame/reinforced concrete core building. The aspect ratio of height to width also exceeds the stipulated limit of 7 for seismic design intensity 7. A 1/50 scaled model is made and tested on shaking table under a series of one and two‐dimensional base excitations with gradually increasing acceleration amplitudes. This paper presents the dynamic characteristics, the seismic responses and the failure mechanism of the structure. The test results demonstrate that the structural system is a good solution to withstand earthquakes. The inter‐storey drift and the overall behaviour meet the requirements of Chinese Design Code. Furthermore, weak positions under seldom‐occurred earthquakes of seismic design intensity 8 are found based on the visible damages on the testing model, and some corresponding suggestions are proposed for the engineering design of the structure under extremely strong earthquake. Copyright © 2006 John Wiley & Sons, Ltd.
Feathers and ‘feather‐like’ integumentary structures in Liaoning birds and dinosaurs
Authors: Fucheng Zhang , Zhonghe Zhou , Dyke Gareth
Published: September 2006

We provide an overview of the known feather and other ‘feather‐like’ integumentary structure types known to‐date in the birds and dinosaurs from the Cretaceous rocks of Liaoning, NE China. These feather‐types are classified and compared with similar structures seen in Mesozoic and extant birds. We consider that integumentary feathers and ‘feather‐like’ structures fall within two major structural categories (‘shafted’ and ‘non‐shafted’). Comments are also made on the possible aerodynamic or insulating function of leg and tail feathers in Mesozoic birds and theropods. Copyright © 2006 John Wiley & Sons, Ltd.
Biological responses to multilayered DNA‐coatings
Authors: van den Beucken J. J. J. P. , Walboomers X. F. , Vos M. R. J. , Sommerdijk N. A. J. M. , Nolte R. J. M. , Jansen J. A.
Published: September 2006

This study was performed to evaluate the basic biological response to deoxyribonucleic acid (DNA)‐based coatings for soft tissue implants. To that end, in vitro experiments were used to study their cytocompatibility, and in vivo subcutaneous implantation studies with transponders in a rat model were performed to evaluate their histocompatibility. The DNA‐based coatings were fabricated using the electrostatic self‐assembly technique using cationic poly‐D‐lysine or poly‐allylamine hydrochloride and anionic DNA. Noncoated substrates served as controls. In vitro, the behavior of primary rat dermal fibroblasts was assessed in terms of cell proliferation and morphology. Both types of multilayered DNA‐coatings significantly increased rat dermal fibroblast proliferation without altering the morphological appearance of the cells. The tissue response to multilayered DNA‐coatings was assessed using an in vivo rat model, in which transponders were inserted subcutaneously for 4 and 12 weeks. No macroscopic signs of inflammation or adverse tissue reactions were observed at implant retrieval. Histological analyses demonstrated a uniform tissue response to all types of implants. All implants were encapsulated in a fibrous tissue capsule without intervening inflammatory cells at the implant surface. Histomorphometrically, multilayered DNA‐coatings induced fibrous tissue capsules with similar quality and thickness compared to noncoated controls. In addition, all fibrous tissue capsules showed similar expression of α‐smooth muscle actin. This study demonstrates that multilayered DNA‐coatings are cytocompatible and histocompatible, and justifies further research on their functionalization with biologically active compounds to modulate tissue responses. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Polypeptide multilayer nanofilm artificial red blood cells
Authors: Palath Naveen , Bhad Sujaykumar , Montazeri Reza , Guidry Christopher A. , Haynie Donald T.
Published: September 2006

Reliable encapsulation of hemoglobin (Hb) within polypeptide multilayer nanofilms has been achieved by a template‐based approach, and protein functionality has been demonstrated postencapsulation. The method is general in scope and could be useful for many other encapsulants. Met‐Hb was adsorbed onto 5 μm‐diameter CaCO3microparticles, and the Hb‐coated particles were encapsulated within a multilayer nanofilm of poly(L‐glutamic acid) (PLGA) and poly(L‐lysine) (PLL) by layer‐by‐layer assembly. The CaCO3templates were then dissolved within the PLGA/PLL nanofilms by addition of ethylenediaminetetraacetic acid. Encapsulation of Hb was proved by fluorescence microscopy, the pH‐dependence of retention of Hb was determined by visible wavelength absorbance, and conversion of the encapsulated met‐Hb to deoxy‐Hb and oxy‐Hb was demonstrated by spectroscopic analysis of the Soret absorption peak under various conditions. It thus has been shown that control of Hb oxygenation within polypeptide multilayer nanofilm artificial cells is possible, and that Hb thus encapsulated can bind, release, and subsequently rebind molecular oxygen. This work therefore represents an advance in the development of polypeptide multilayer film artificial red blood cells. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Different outcomes in urethral reconstruction using elastin and collagen patches and conduits in rabbits
Authors: Xie Hua , Campbell Carmen E. , Shaffer Brian S. , Gregory Kenton W.
Published: September 2006

Objectives: To study the feasibility of urethral reconstruction with two urethroplasty techniques using an elastin and collagen heterograft in rabbits. Materials and Methods: Fifty‐two male rabbits were studied. Two types of injury, (1) a 1.5 ×× 0.6 cm2 semicircumferential defect; (2) a 1.5 cm segmental defect of the penile urethra, were created and repaired using size‐matched elastin and collagen patches or tubed conduits. Urethral repair by primary closure for the type 1 injury and a tubularized autologous bladder mucosal graft for the type 2 injury served as controls. At 3 months, urethral diameter was measured with retrograde urethrography. The animals were then euthanized for histological examination. Results: The postoperative complication rate was significantly higher in the urethral reconstructions using tubed collagen (83%) and elastin (50%) grafts compared to the patch onlay grafts (p = 0.001 for collagen and p = 0.01 for elastin) and tubularized ABM (10%, p = 0.003 and 0.05, respectively). At the type 2 injury site, a dense circumferential fibrosis developed after all repairs. Only minimal ventral fibrosis presented in the type 1 injury repair. The intensity of chronic inflammation and fibrosis was greatest when collagen was used for the urethral repair. In the elastin urethral repairs the urethral diameter decreased significantly for the tubed repair compared to the patch onlay (p = 0.02). Conclusion: Urethral injury repair using elastin and collagen biomaterials is feasible in the rabbit model. The results of onlay urethroplasty using the elastin and collagen patches are significantly superior to those using the elastin and collagen tubed conduits. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Photocrosslinkable hydrogel for myocyte cell culture and injection
Authors: Yeo Yoon , Geng Wenliang , Ito Taichi , Kohane Daniel S. , Burdick Jason A. , Radisic Milica
Published: September 2006

Conventional treatment options for myocardial infarction are limited by the inability of mature myocardium to regenerate after injury. Although functional improvements after injection of cells and growth factors have been demonstrated, the clinical utility of this procedure has been hampered by poor cell localization, low survival, and rapid clearance of injected growth factors. The main objective of this study was to evaluate the applicability of a hydrogel, based on photocrosslinkable chitosan and acryloyl‐poly(ethylene glycol)‐RGDS (Az‐chitosan/Acr‐PEG‐RGD) for myocyte cell culture and myocardial injection. Chitosan was modified with photoreactive azidobenzoic acid and Acr‐PEG‐RGD was synthesized by reacting YRGDS with an equimolar amount of acryloyl‐PEG‐N‐hydroxysuccinimide. For injection and encapsulation each polymer was dissolved in Di‐H2O (pH 6.4), the solutions were mixed and crosslinked by UV application (4 mW/cm2). C2C12 myoblasts proliferated and differentiated on hydrogels containing 5 mM RGD but not on the pure photocrosslinked chitosan. In vitro, the crosslinked hydrogels retained 80% of encapsulated VEGF for 24 days. Live/dead staining of neonatal rat cardiomyocytes encapsulated into Az‐chitosan/Acr‐PEG‐RGD hydrogels indicated high cell viability upon UV crosslinking. Ex vivo, we localized the hydrogel on the surface and in the ventricle wall of an adult rat heart by brief (2 min) UV light application. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
A Bayesian approach on molecules and behavior: reconsidering phylogenetic and evolutionary patterns of the Salamandridae with emphasis on Triturus newts
Authors: Steinfartz Sebastian , Vicario Saverio , Arntzen J.W. , Caccone Adalgisa
Published: September 2006

The monophyly of European newts of the genus Triturus within the family Salamandridae has for decades rested on presumably homologous behavioral and morphological characters. Molecular data challenge this hypothesis, but the phylogenetic position of Triturus within the Salamandridae has not yet been convincingly resolved. We addressed this issue and the temporal divergence of Triturus within the Salamandridae with novel Bayesian approaches applied to DNA sequence data from three mitochondrial genes (12S, 16S and cytb). We included 38 salamandrid species comprising all 13 recognized species of Triturus and 16 out of 17 salamandrid genera. A clade comprising all the “Newts” can be separated from the “True Salamanders” and Salamandrina clades. Within the “Newts” well‐supported clades are: Tylototriton–Pleurodeles, the “New World Newts” (Notophthalmus–Taricha), and the “Modern Eurasian Newts” (Cynops, Pachytriton, Paramesotriton=together the “Modern Asian Newts”, Calotriton, Euproctus, Neurergus and Triturus species). We found that Triturus is a non‐monophyletic species assemblage, which includes four groups that are themselves monophyletic: (i) the “Large‐Bodied Triturus” (six species), (ii) the “Small‐Bodied Triturus” (five species), (iii) T. alpestris and (iv) T. vittatus. We estimated that the last common ancestor of Triturus existed around 64 million years ago (mya) while the root of the Salamandridae dates back to 95 mya. This was estimated using a fossil‐based molecular dating approach and an explicit framework to select calibration points that least underestimated their corresponding nodes. Using the molecular phylogeny we mapped the evolution of life history and courtship traits in Triturus and found that several Triturus‐specific courtship traits evolved independently. J. Exp. Zool. (Mol. Dev. Evol.) 306B, 2006. © 2006 Wiley‐Liss, Inc.
Imaging living mice using a 1‐T compact MRI system
Authors: Inoue Yusuke , Nomura Yukihiro , Haishi Tomoyuki , Yoshikawa Kohki , Seki Takahiro , Tsukiyama‐Kohara Kyoko , Kai Chieko , Okubo Toshiyuki , Ohtomo Kuni
Published: September 2006

Purpose

To determine the feasibility of imaging living mice with a 1‐T compact MRI system and investigate appropriate imaging techniques for use in routine animal experiments.

Materials and Methods

An MRI system consisting of a 1‐T permanent magnet and compact console was used. Images of the entire trunks of living mice were obtained on the system using a T1‐weighted three‐dimensional fast low‐angle shot (3D FLASH) sequence, and image quality was evaluated in relation to imaging techniques.

Results

Restraint of respiratory motion improved the image quality. Decreasing the slice thickness reduced artificial inhomogeneity in signal intensity (SI). Substantial effects of TR and FA on image quality were also demonstrated. With the determined techniques, images covering the entire trunk with a voxel size of 0.26 × 0.26 × 0.52 mm were acquired in an acquisition time of five minutes 28 seconds and a total experiment time of <20 minutes, and various organs and subcutaneous tumors were clearly visualized.

Conclusion

The compact MRI system provides images of living mice with acceptable quality in a reasonable time. Considering its convenience, it appears to be suitable for use in routine mouse experiments. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Cine flow measurements using phase contrast with undersampled projections: In vitro validation and preliminary results in vivo
Authors: Wentland Andrew L. , Korosec Frank R. , Vigen Karl K. , Wieben Oliver , Fine Jason P. , Grist Thomas M.
Published: September 2006

Purpose

To assess the accuracy of flow measurements in vitro and in vivo during scan times shorter than a breath‐hold using a 2D cine phase contrast (PC) undersampled radial acquisition method, which may be useful for measuring flow, especially in vessels subject to motion during respiration.

Materials and Methods

For in vitro assessment, a flow phantom was imaged at various flow rates and undersampling factors. For in vivo assessment, five normal subjects were imaged and the flow rate in the aorta was compared with the sum of the flow rates in the iliac arteries.

Results

For results in vitro, the accuracy of flow measurements was maintained with scan times as low as 13–17 seconds. For results in vivo, scans acquired in less than 25 seconds provided flow measurements in the aorta that corresponded well to the sum of flow measurements in the iliac arteries.

Conclusion

The undersampled radial acquisition cine PC technique provided accurate flow measurements in a flow phantom and in healthy human volunteers in scan times shorter than a typical breath‐hold. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
T1‐ and T2‐weighted fast spin‐echo imaging of the brachial plexus and cervical spine with IDEAL water–fat separation
Authors: Reeder Scott B. , Yu Huanzhou , Johnson Jane W. , Shimakawa Ann , Brittain Jean H. , Pelc Norbert J. , Beaulieu Christopher F. , Gold Garry E.
Published: September 2006

Purpose

To compare the iterative decomposition of water and fat with echo asymmetry and least‐squares estimation (IDEAL) method with fat‐saturated T1‐weighted (T1W) and T2W fast spin‐echo (FSE) and short‐TI inversion recovery (STIR) imaging of the brachial plexus and cervical spine.

Materials and Methods

Images acquired at 1.5T in five volunteers using fat‐saturated T1W and T2W FSE imaging and STIR were compared with T1W and T2W IDEAL‐FSE images. Examples of T1W and T2W IDEAL‐FSE images acquired in patients are also shown.

Results

T1W and T2W IDEAL‐FSE demonstrated superior fat suppression (P < 0.05) and image quality (P < 0.05), compared to T1W and T2W fat‐saturated FSE, respectively. SNR performance of T1W‐IDEAL‐FSE was similar to T1W FSE in the spinal cord (P = 0.250) and paraspinous muscles (P = 0.78), while T2W IDEAL‐FSE had superior SNR in muscle (P = 0.02) and CSF (P = 0.02), and marginally higher cord SNR (P = 0.09). Compared to STIR, T2W IDEAL‐FSE demonstrated superior image quality (P < 0.05), comparable fat suppression (excellent, P = 1.0), and higher SNR performance (P < 0.001).

Conclusion

IDEAL‐FSE is a promising method for T1W and T2W imaging of the brachial plexus and cervical spine. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.